JP4097870B2

JP4097870B2 - Wood cement board

Info

Publication number: JP4097870B2
Application number: JP2000020248A
Authority: JP
Inventors: 秀憲河合
Original assignee: Nichiha Corp
Current assignee: Nichiha Corp
Priority date: 2000-01-28
Filing date: 2000-01-28
Publication date: 2008-06-11
Anticipated expiration: 2020-01-28
Also published as: JP2001213660A

Description

【０００１】
【発明の属する技術分野】
本発明は木質補強材がセメント硬化物のマトリクス内に分散している木質セメント板の廃材粉砕物を混合した木質セメント板に関するものである。
【０００２】
【従来の技術】
木質セメント板は、木片、木質繊維束、木毛、木粉、木質パルプ等の木質補強材がセメント硬化物マトリクス内に分散した構造を有しており、外壁材、屋根材等の建築板として多用されている。該木質セメント板を製造する際、切削工程において切屑や端切れ等の廃材が製品の１０〜３０％程度発生する。このような木質セメント板廃材は従来は主として廃棄処分にしていた。しかし公害規制が厳しくその上廃棄処分場の確保が困難となって廃棄処分費用が嵩んでいる現状からみて、該木質セメント板廃材の再利用が強く望まれている。上記木質セメント板廃材の再利用方法としては、該木質セメント板廃材の粉砕物を木質セメント板原料に混合して木質セメント板を製造する方法が検討されており、例えば特開平９−２８６６５７号には木質セメント板廃材を１６メッシュ以下の粒径に粉砕し木質セメント板の原料に混合することが提案されている。
【０００３】
【発明が解決しようとする課題】
しかしながら木質セメント板廃材は木質補強材が分散しているセメント硬化物からなり、硬化性に乏しいので多量の混合は製品の強度低下を招くと云う問題点があった。
【０００４】
【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、木質補強材がセメント硬化物のマトリクス内に分散している木質セメント板であって、緻密構造を有する表裏層と粗構造を有する芯層とからなる三層構造を有し、上記表裏層には、絶乾比重が０．９０〜１．１０で、更にかさ比重が０．２０〜０．６０の木質セメント板廃材軽粉砕物が２０重量％以下の量で含まれており、上記芯層には、絶乾比重が１．１０〜１．３０で、更にかさ比重が０．８０〜１．２０の木質セメント板廃材重粉砕物が４０重量％以下の量で含まれている木質セメント板を提供するものである。また本発明では、前記木質セメント板は、表裏層の木質補強材として、目開き４．５ mm 以下の粒径の木片および／または目開き０．５〜１．５ mm の粒径の木粉が使用されており、また、芯層の木質補強材として、目開き４．５〜１０ mm の粒径の木片および／または平均径１．０ mm 、長さ２０ mm の木質繊維束が使用されており、乾式法によって製造されたものである。更に前記木質セメント板廃材軽粉砕物には、木質成分が２５〜５０重量％含まれており、前記木質セメント板廃材重粉砕物には、無機質成分が６０〜９０重量％含まれていることが望ましい。また前記木質セメント板廃材軽粉砕物および前記木質セメント板廃材重粉砕物は、木質セメント板廃材をハンマーミルで一次粉砕し、更に該一次粉砕物をローラミルで二次粉砕し、該二次粉砕物を絶乾比重とかさ比重とで分級して得られたものであり、粒径が１μ m 以上１０００μ m 以下であることが望ましい。更にまた前記木質セメント板廃材軽粉砕物および／または前記木質セメント板廃材重粉砕物の一部に代えて前記木質セメント板の一次粉砕物が、表裏層においては２重量％以下、芯層においては２８重量％以下の量で添加されていることが望ましい。
【０００５】
〔木質補強材〕
本発明において用いられる木質補強材としては木片、木質繊維束、木毛、木粉、木質パルプ等、従来の木質セメント板に用いられる木質補強材と同様なものがある。望ましい木質補強材としては巾０．５〜２mm、長さ１〜２０mm、アスペクト比（長さ／厚み）２０〜３０の木片や、径が０．１〜２．０mm、長さが２〜３５mm、望ましくは１０〜３０mmの分枝および／または彎曲および／または折曲させることにより嵩高くされた木質繊維束がある。
【０００６】
〔セメント系無機材料〕
本発明において用いられるセメント系無機材料としては、ポルトランドセメント、高炉スラグセメント、シリカセメント、フライアッシュセメント、アルミナセメント等が例示される。
【０００７】
〔木質セメント板廃材〕
本発明が対象とする木質セメント板とは、木片、木質繊維束、木毛、木粉、木質パルプ等の木質補強材を使用した木質セメント板であって、上記木質セメント板廃材とは、該木質セメント板を例えば外壁材や屋根材等に使用した建築物の取壊し、改修等の際に発生する廃材、あるいは該木質セメント板を製造する際に切削工程等において発生する切屑、端切れ等である。本発明において望ましい木質セメント板は木片および／または木質繊維束を木質補強材として使用したものである。
【０００８】
上記木質セメント板廃材はハンマーミルによって通常０．５mm〜２．０mmの粒径の一次粉砕物に粉砕され、該一次粉砕物は木質セメント板原料の一部として再使用されているが、本発明では更に該一次粉砕物をローラミルによって二次粉砕した二次粉砕物を原料として使用する。ローラミルとしては遠心ローラミル、バウルミル、ゼゴミル、オングミル、竪型ローラを用いた竪型ミル等がある。
【０００９】
本発明においては、上記二次粉砕物をエアー分級によって絶乾比重０．９０〜１．２０、望ましくは０．９０〜１．１０、更に望ましくはかさ比重０．２０〜０．６０の軽粉砕物と、絶乾比重１．００〜１．３０、望ましくは１．１０〜１．３０、更に望ましくはかさ比重０．８０〜１．２０の重粉砕物とに分級する。該軽粉砕物には通常２５〜５０重量％の木質成分と、５０〜７５重量％の無機質成分とが含まれ、該重粉砕物には通常１０〜４０重量％の木質成分と、６０〜９０重量％の無機質成分とが含まれる。
【００１０】
このように二次粉砕物を絶乾比重で分級すれば、木質成分を多く含む粉砕物は絶乾比重が小さく、木質成分が少なく無機成分を多く含む粉砕物は絶乾比重が大きいので、木質成分を多く含む粉砕物（軽粉砕物）と無機成分を多く含む粉砕物（重粉砕物）とに容易に分級することが出来る。
【００１１】
〔その他の原料成分〕
上記原料の他に更にセメントの一部をケイ砂、ケイ石粉、シリカヒューム、高炉スラグ、フライアッシュ、シラスバルーン、パーライト、ベントナイト、ケイソウ土等のケイ酸含有物質および／またはボゾラン物質で置換してもよいし、あるいは塩化カルシウム、塩化マグネシウム、塩化鉄、塩化アルミニウム、塩化ナトリウム、塩化カリウム、塩化リチウム等の塩化物の無水物あるいは結晶化物、硫酸アルミニウム、ミョウバン、硫酸鉄、硫酸リチウム、硫酸ナトリウム、硫酸カリウム、硫酸マグネシウム等の硫酸塩の無水物あるいは結晶化物、硝酸カルシウム、亜硝酸カルシウム等の硝酸塩、亜硝酸塩の無水物あるいは結晶化物、ギ酸カルシウム、酢酸カルシウム等のギ酸塩、酢酸塩の無水化物あるいは結晶化物、アルミン酸ソーダ、水ガラス等のセメント硬化促進剤やワックス、パラフィン、シリコン等の撥水剤、発泡性ポリスチレンビーズ等の発泡性熱可塑性プラスチックビーズ等を添加してもよい。
【００１２】
〔木質セメント板の製造〕
本発明の木質セメント板は粗構造を有する芯層の表裏面に緻密構造を有する表裏層を積層した三層構造とする。このような三層構造の木質セメント板の場合、表裏層用の原料混合物Ａの組成は、通常セメント３０〜６０重量％、木質補強材５〜２５重量％、ケイ酸含有物質１５〜５０重量％、木質セメント板廃軽粉砕物２０重量％以下であり、芯層用の原料混合物Ｂの組成は、通常セメント３０〜６０重量％、木質補強材５〜３５重量％、ケイ酸含有物質１５〜５０重量％、木質セメント板廃材重粉砕物４０重量％以下であり、所望なれば発泡性ポリスチレンビーズ０．５〜５重量％が添加されてもよい。
上記原料混合物Ａ、Ｂには通常更にセメント硬化促進剤が数重量％以下の量で添加される。
【００１３】
上記表裏層の原料混合物Ａの場合には、緻密構造を与えるために木質補強材として通常目開き４．５mm以下の粒径の木片や目開き０．５〜１．５mmの粒径の木粉等の微細木質補強材を使用し、また上記芯層の原料混合物Ｂの場合には粗構造を与えるために木質補強材として通常目開き４．５〜１０mmの粒径の木片や平均径１．０mm、長さ２０mmの木質繊維束等の粗大木質補強材を使用することが望ましい。
【００１４】
更に本発明においては上記木質セメント板廃材の二次粉砕物の軽粉砕物および／または重粉砕物の一部に代えて木質セメント板廃材の一次粉砕物を表裏層においては２重量％以下、芯層においては２８重量％以下の量で使用してもよい。
【００１５】
本発明の木質セメント板の製造方法としては、工程の連続化が容易で装置も簡単な乾式法を採用することが望ましい。乾式法の工程１においては、型板上に上記原料混合物Ａをマット状に散布し、次いでその上に上記原料混合物Ｂをマット状に散布し、更にその上に上記原料混合物Ａをマット状に散布するのであるが、この際原料混合物Ａおよび原料混合物Ｂにはセメントの硬化反応のためにそれぞれ水を３０〜５０重量％添加しておく。木質補強材として木片と木質繊維束、特に上記分枝および／または彎曲および／または折曲させることによって嵩高くされた木質繊維束を用いると、原料混合物がほぐれ易くなり、型板上に均一に散布し易くなる。
【００１６】
連続製造法においては上記型板は搬送板として多数個ベルトコンベア上に載置並列せしめられる。
型板上に散布された原料混合物は所望なればロール等によって若干押圧されることによって厚みを調節されかつ表面を平滑化されてマットとされ、該マットはそれから工程２において水分存在下に圧締予備硬化され所望の形状に成形される。
【００１７】
圧締条件は通常圧締圧１０〜３０kgf ／cm²、温度６０〜８０℃、時間６〜２０時間程度で行われ、加熱は通常蒸気にて行われる。圧締は二つの型板間に上記マットを挟圧することによって行われるが、該型板面には所定の形状、凹凸模様等が施されてもよい。上記工程２の圧締予備硬化によって得られた予備硬化物は工程３においてオートクレーブ中にて養生される。
【００１８】
養生条件は通常圧力６〜２０kgf ／cm²、温度１６０〜１８０℃、時間５〜１０時間程度である。上記オートクレーブ養生によりセメントとケイ酸含有物質とのケイ酸カルシウム反応は完全に行われ、かつ芯層に発泡性熱可塑性プラスチックビーズを添加した場合には該発泡性熱可塑性プラスチックビーズは完全に発泡し、そして該発泡性熱可塑性プラスチックビーズの発泡によって形成されたプラスチック発泡体粒は溶融してセル中の発泡剤が外界へ逃散し、該プラスチック発泡体粒は急速に収縮して芯層内部に多数の空孔が形成される。そして該空孔内壁面には該プラスチック発泡体粒にもとずく熱可塑性プラスチックコーティング層が形成される。
【００１９】
また工程３においては２５℃の常温で７日間養生してもよい。ただしこの場合はケイ酸含有物質の配合比を下げて、セメントを増やした配合とすることが望ましい。
このようにして本発明の木質セメント板が製造されるが、本発明の木質セメント板の表裏層の厚みは通常全体の厚みの１０〜３０％、密度は０．８〜１．１ｇ／cm³とする。
【００２０】
【作用】
木質セメント板廃材をハンマーミルで粉砕すると、粒径が０．５mm〜２．０mmの一次粉砕物が得られる。このような一次粉砕物は外側にセメント硬化物、内側に未反応セメント分を有する。このような一次粉砕物を更にローラミルで二次粉砕して得られる二次粉砕物は粒径が１μm 以上１０００μm 以下であり、内側の未反応セメント分が外部に露出するようになる。
【００２１】
したがってこのような二次粉砕物は反応性が高くなり、木質セメント板の原料中のセメントと共に硬化反応を起す。特に本発明では二次粉砕物を更に絶乾比重が０．９０〜１．２０以下、望ましくは０．９０〜１．１０、更に望ましくはかさ比重が０．２０〜０．６０の軽粉砕物と絶乾比重が１．００〜１．３０、望ましくは１．１０〜１．３０、更に望ましくはかさ比重が０．８０〜１．２０の重粉砕物とに分級し、木質成分を多量に含む軽粉砕物は表裏層に添加するから、その分表裏層の木質補強材を節約することが出来るし、更に反応性の高い無機質成分も含んでいるからその分セメント、ケイ酸含有物質、ポゾラン物質等を節約することも出来る。上記したように表裏層に使用する木質補強材はもっとも微細な木粉でも平均で目開き１．０mmであるから、該軽粉砕物はそれよりも微細であるので（１０００μm 以下）、原料混合物Ａ中に均一に混合され易く、木質補強材による補強効果が有効に発揮されるし、また該木質補強材は木質セメント板の表面平滑性を阻害せずかえって向上せしめる。
【００２２】
一方重粉砕物は芯層に添加するが、上記軽粉砕物より更に無機質成分を多く含んで反応性が高いので、セメントと共に良好に硬化反応を起す。木質セメント板は製造直後においてもセメント成分の６割近くは未反応物として残っており、該未反応物はセメント硬化物マトリクスの細孔中に充填している。このように未反応物がセメント硬化物マトリクス細孔中に充填していると、木質セメント板の寸法安定性が悪くなる。
【００２３】
本発明では芯層においてセメント硬化物マトリクスの細孔中に上記重粉砕物も充填され、該重粉砕物には未反応セメント分以外に反応が終了したセメント硬化物も含んでいるので充填効果があり、細孔に水等が入り難くなり収縮、膨潤が抑えられる。更に該細孔中で木質セメント板に残っている未反応物とある程度反応するので、木質セメント板の寸法安定性が大幅に改良され、また表裏層と同様に木質補強材による補強効果も有効に発揮される。
【００２４】
【発明の実施の形態】
本実施例では下記の組成の原料を使用して乾式法によって製造された３層構造の木質セメント板の廃材の粉砕物を使用した。
＜表裏層＞
セメント４７．５重量％
ケイ砂３２．５〃
木片１４．５〃
木粉５．５〃
硬化剤２．０〃
＜芯層＞
セメント３３．０〃
フライアッシュ２２．０〃
木片６．０〃
木質繊維束１０．０〃
発泡性ポリスチレンビーズ２．０〃
硬化剤２．０〃
リジェクト２７．０〃
一次養生は７０℃，１０時間とし、二次養生としてオートクレーブ養生を１６５℃、７時間行った。
上記木質セメント板の廃材をハンマーミルによって粉砕して粒径０．５〜２．０mmの一次粉砕物を得た。更に該一次粉砕物をローラミルで二次粉砕し、エアー分級によってかさ比重０．４０の軽粉砕物とかさ比重１．００の重粉砕物とを得た。
表１に示す組成の混合物に水を４０〜５０重量％添加した加水混合物を用いて表裏層部と芯層部とを有する三層構造の木質セメント板である本発明の試料１〜５および比較試料１を乾式法によって作成した。
【００２５】
【表１】

【００２６】
試料および比較試料は、下型板上に表１に示す表層部組成の混合物を所定量散布して表層部マットをフォーミングし、その上に表１に示す芯層部組成の混合物を所定量散布して芯層部マットをフォーミングし、更にその上から上記表層部組成の混合物を所定量散布して裏層マットをフォーミングし、その上から上型板を当接し、１０kgｆ／ｃm²の面圧でプレス圧締、７０℃、１０時間の予備養生、圧力６kgf ／cm²、温度１６５℃、７時間のオートクレーブ養生および乾燥することにより三層構造で表裏層／芯層の重量比＝１／３の木質セメント板試料を作成した。
このようにして作成された各試料の各種物性を測定した。その結果は表２に示される。
【００２７】
【表２】

【００２８】
表２によれば、木質セメント板廃材の一次粉砕物のみを使用した比較例１は、軽粉砕物と重粉砕物とを使用した本発明の実施例１〜５に比して強度が低いことが認められる。
【００２９】
【発明の効果】
本発明では木質セメント板の廃材のハンマーミル粉砕による粉砕物を添加するうえに、更にローラミルで二次粉砕した絶乾比重０．９０〜１．２０の軽粉砕物を表裏層に、絶乾比重１．００〜１．３０の重粉砕物を芯層に添加するので、木質セメント板の廃材を大量有効に利用して、高強度かつ良好な寸法安定性を有する木質セメント板を提供することが出来る。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wood cement board in which a waste material pulverized material of a wood cement board in which a wood reinforcing material is dispersed in a matrix of a hardened cement material is mixed.
[0002]
[Prior art]
The wood cement board has a structure in which wood reinforcing materials such as wood chips, wood fiber bundles, wood wool, wood powder, wood pulp are dispersed in the cement hardened matrix, and as a construction board for outer wall materials, roofing materials, etc. It is used a lot. When manufacturing the wood cement board, waste materials such as chips and cuts are generated about 10 to 30% of the product in the cutting process. Conventionally, such wood cement board waste has been mainly disposed of. However, in view of the current situation in which pollution control is strict and it is difficult to secure a disposal site and the disposal cost is increased, it is strongly desired to reuse the wood cement board waste. As a method of reusing the wood cement board waste material, a method of manufacturing a wood cement board by mixing a pulverized product of the wood cement board waste material with a wood cement board raw material has been studied, for example, in JP-A-9-286657. It is proposed that the wood cement board waste is pulverized to a particle size of 16 mesh or less and mixed with the raw material of the wood cement board.
[0003]
[Problems to be solved by the invention]
However, the wood cement board waste material is made of a hardened cement material in which the wood reinforcing material is dispersed and has poor curability, so that a large amount of mixing has a problem that the strength of the product is reduced.
[0004]
[Means for Solving the Problems]
As a means for solving the above-described conventional problems, the present invention is a wood cement board in which a wood reinforcing material is dispersed in a matrix of a hardened cement material, and includes a front and back layer having a dense structure and a core layer having a rough structure. The above-mentioned front and back layers have an absolute dry specific gravity of 0.90 to 1. 1 0, are included in a more or Is specific gravity amount wood cement board waste light granulated material of 20 wt% or less of 0.20 to 0.60, in the core layer, absolute dry specific gravity of 1. The present invention provides a wood cement board having a weight ratio of 10 to 1.30 and a wood cement board waste material heavy pulverized material having a bulk specific gravity of 0.80 to 1.20 in an amount of 40% by weight or less. In the present invention, the wood cement board is a wood reinforcing material having a mesh size of 4.5 mm or less and / or a wood powder having a mesh size of 0.5 to 1.5 mm , as a wood reinforcing material for the front and back layers. There are used, also, as a wood reinforcement of the core layer, wood and / or the average diameter 1.0 mm of the particle size of the mesh 4.5 to 10 mm, the wood fiber bundles of 20 mm length are used and, those produced by a dry method. More the wood cement board waste light ground product contains wood components 25 to 50 wt%, the wood cement board waste heavy pulverized material be inorganic component is contained 60 to 90 wt% desirable. Also, the wood cement board waste light pulverized material and the wood cement board waste heavy grind, a wood cement board waste material to primary pulverizing in a hammer mill, and the secondary pulverization further the primary grind at a roller mill, the secondary pulverized material the are those obtained by classifying by the absolute dry specific gravity and bulk density is desirably a particle diameter is less than 1 [mu] m or more 1000 [mu] m. Furthermore the wood cement board waste light pulverized product and / or primary pulverized instead of a part the wood cement board of the wood cement board waste heavy pulverized material, 2 wt% or less in the front and back layers, the core layer It is desirable that it is added in an amount of 28% by weight or less .
[0005]
[Wood reinforcement]
Examples of the wood reinforcing material used in the present invention include wood fragments, wood fiber bundles, wood wool, wood powder, wood pulp, and the like, which are similar to the wood reinforcing materials used for conventional wood cement boards. Desirable wood reinforcement is 0.5 to 2 mm in width, 1 to 20 mm in length, a piece of wood having an aspect ratio (length / thickness) of 20 to 30, a diameter of 0.1 to 2.0 mm, and a length of 2 to 35 mm. Preferably, there are wood fiber bundles that are made bulky by branching and / or folding and / or folding, preferably 10-30 mm.
[0006]
[Cement-based inorganic materials]
Examples of the cement-based inorganic material used in the present invention include Portland cement, blast furnace slag cement, silica cement, fly ash cement, and alumina cement.
[0007]
[Wood cement board waste]
The wood cement board targeted by the present invention is a wood cement board using a wood reinforcing material such as wood fragments, wood fiber bundles, wood wool, wood powder, wood pulp, etc., and the wood cement board waste material is Waste wood generated when demolishing or refurbishing a building that uses wood cement boards, for example, as external wall materials or roofing materials, or chips, cuts, etc., generated during the cutting process when manufacturing the wood cement boards . In the present invention, a desirable wood cement board is obtained by using a piece of wood and / or a wood fiber bundle as a wood reinforcing material.
[0008]
The wood cement board waste material is pulverized into a primary pulverized product having a particle size of usually 0.5 mm to 2.0 mm by a hammer mill, and the primary pulverized product is reused as a part of the raw material of the wooden cement board. Then, a secondary pulverized product obtained by secondary pulverizing the primary pulverized product with a roller mill is used as a raw material. Examples of the roller mill include a centrifugal roller mill, a bawl mill, a Zegomyle, an ong mill, and a vertical mill using a vertical roller.
[0009]
In the present invention, the secondary pulverized product is lightly pulverized by air classification and has an absolute dry specific gravity of 0.90 to 1.20, preferably 0.90 to 1.10, and more preferably a bulk specific gravity of 0.20 to 0.60. And a heavy pulverized product having an absolute dry specific gravity of 1.00 to 1.30, preferably 1.10 to 1.30, more preferably a bulk specific gravity of 0.80 to 1.20. The light pulverized product usually contains 25 to 50% by weight of a wood component and 50 to 75% by weight of an inorganic component, and the heavy pulverized product usually contains 10 to 40% by weight of a wood component and 60 to 90%. % By weight of an inorganic component.
[0010]
In this way, if the secondary pulverized product is classified by the absolute dry specific gravity, the pulverized product containing a large amount of the wood component has a low absolute dry specific gravity, and the pulverized product containing a small amount of the wood component and containing a lot of inorganic components has a high absolute dry specific gravity. It can be easily classified into a pulverized product containing a large amount of components (lightly pulverized product) and a pulverized product containing a large amount of inorganic components (heavy pulverized product).
[0011]
[Other ingredients]
In addition to the above raw materials, a part of the cement is further replaced with silica-containing materials such as silica sand, silica stone powder, silica fume, blast furnace slag, fly ash, shirasu balloon, perlite, bentonite, diatomaceous earth and / or bozolan materials. Or, anhydrous or crystallized chloride such as calcium chloride, magnesium chloride, iron chloride, aluminum chloride, sodium chloride, potassium chloride, lithium chloride, aluminum sulfate, alum, iron sulfate, lithium sulfate, sodium sulfate, Anhydrous or crystallized sulfates such as potassium sulfate and magnesium sulfate, nitrates such as calcium nitrate and calcium nitrite, anhydrous or crystallized nitrites, formate such as calcium formate and calcium acetate, and anhydrous anhydrides of acetate Or crystallized product, sodium aluminate, water Cement accelerators or wax such lath, paraffin, water repellent agents such as silicon, a foamable thermoplastic plastic beads such as expandable polystyrene beads may be added.
[0012]
[Manufacture of wood cement board]
The wood cement board of the present invention has a three-layer structure in which front and back layers having a dense structure are laminated on the front and back surfaces of a core layer having a rough structure. In the case of such a three-layer structure wood cement board, the composition of the raw material mixture A for the front and back layers is usually 30 to 60% by weight of cement, 5 to 25% by weight of a wood reinforcing material, and 15 to 50% by weight of a silicic acid-containing substance. The composition of the raw material mixture B for the core layer is usually 30 to 60% by weight of cement, 5 to 35% by weight of the wood reinforcing material, and 15 to 50% of the silicic acid-containing substance. % By weight, 40% by weight or less of the wood cement board waste material heavy pulverized product, and 0.5 to 5% by weight of expandable polystyrene beads may be added if desired.
A cement hardening accelerator is usually added to the raw material mixtures A and B in an amount of several weight percent or less.
[0013]
In the case of the raw material mixture A for the front and back layers, a wood piece having an opening of 4.5 mm or less or a wood powder having an opening of 0.5 to 1.5 mm is usually used as a wood reinforcing material to give a dense structure. In the case of the raw material mixture B for the core layer, a wood piece having an opening of 4.5 to 10 mm or an average diameter of 1. It is desirable to use a coarse wood reinforcing material such as a wood fiber bundle of 0 mm and a length of 20 mm.
[0014]
Further, in the present invention, the primary pulverized material of the wood cement board waste material is replaced by 2% by weight or less in the front and back layers in place of a part of the lightly pulverized material and / or heavy pulverized material of the above-mentioned wood cement board waste material. In the layer, it may be used in an amount of 28% by weight or less.
[0015]
As a method for producing the wood cement board of the present invention, it is desirable to adopt a dry method in which continuation of the process is easy and the apparatus is simple. In step 1 of the dry method, the raw material mixture A is spread in a mat shape on a template, then the raw material mixture B is spread in a mat shape thereon, and the raw material mixture A is further formed in a mat shape. At this time, 30 to 50% by weight of water is added to the raw material mixture A and the raw material mixture B for cement hardening reaction. When wood fragments and wood fiber bundles, especially wood fiber bundles made bulky by bending and / or bending and / or bending, are used as the wood reinforcing material, the raw material mixture becomes easy to loosen and uniformly on the template. Easy to spread.
[0016]
In the continuous manufacturing method, a large number of the above-mentioned templates are placed on a belt conveyor as a conveying plate and arranged in parallel.
If desired, the raw material mixture spread on the template is slightly pressed by a roll or the like to adjust the thickness and smooth the surface to form a mat, which is then pressed in the presence of moisture in step 2. Pre-cured and formed into a desired shape.
[0017]
The pressing conditions are usually a pressing pressure of 10 to 30 kgf / cm ² , a temperature of 60 to 80 ° C., and a time of 6 to 20 hours, and heating is usually performed with steam. The pressing is performed by sandwiching the mat between two mold plates. However, a predetermined shape, a concavo-convex pattern, or the like may be applied to the template surface. The precured material obtained by the pressure precuring in Step 2 is cured in an autoclave in Step 3.
[0018]
The curing conditions are usually a pressure of 6 to 20 kgf / cm ² , a temperature of 160 to 180 ° C., and a time of about 5 to 10 hours. By the autoclave curing, the calcium silicate reaction between the cement and the silicate-containing substance is completely carried out, and when the foamable thermoplastic beads are added to the core layer, the foamable thermoplastic beads are completely foamed. The foamed plastic foam particles formed by foaming of the foamable thermoplastic beads are melted and the foaming agent in the cells escapes to the outside, and the plastic foam particles are rapidly shrunk to form a large number inside the core layer. Holes are formed. A thermoplastic coating layer based on the plastic foam particles is formed on the inner wall surface of the pores.
[0019]
Further, in step 3, curing may be performed at room temperature of 25 ° C. for 7 days. However, in this case, it is desirable to lower the mixing ratio of the silicic acid-containing substance and increase the cement.
In this way, the wood cement board of the present invention is produced. The thickness of the front and back layers of the wood cement board of the present invention is usually 10 to 30% of the total thickness, and the density is 0.8 to 1.1 g / cm ^3. And
[0020]
[Action]
When the wood cement board waste material is pulverized with a hammer mill, a primary pulverized product having a particle size of 0.5 mm to 2.0 mm is obtained. Such a primary pulverized product has a hardened cement material on the outside and an unreacted cement content on the inside. The secondary pulverized product obtained by further secondary pulverizing such a primary pulverized product with a roller mill has a particle size of 1 μm or more and 1000 μm or less, and the inner unreacted cement is exposed to the outside.
[0021]
Therefore, such a secondary pulverized product becomes highly reactive and causes a hardening reaction together with the cement in the raw material of the wood cement board. In particular, in the present invention, the secondary pulverized product is a lightly pulverized product having an absolute dry specific gravity of 0.90 to 1.20 or less, preferably 0.90 to 1.10, more preferably a bulk specific gravity of 0.20 to 0.60. And an absolute dry specific gravity of 1.00 to 1.30, preferably 1.10 to 1.30, more preferably a bulk specific gravity of 0.80 to 1.20, and a large amount of wood components. Since the lightly pulverized product is added to the front and back layers, it can save the wood reinforcing material of the front and back layers, and also contains highly reactive inorganic components, so that cement, silicic acid-containing material, pozzolana Substances can be saved. As described above, since the wood reinforcing material used for the front and back layers has an average opening of 1.0 mm even with the finest wood powder, the lightly pulverized product is finer than that (1000 μm or less), so the raw material mixture A The wood reinforcing material is easily mixed uniformly and the reinforcing effect of the wood reinforcing material is effectively exhibited, and the wood reinforcing material improves the surface smoothness of the wood cement board without hindering.
[0022]
On the other hand, the heavy pulverized product is added to the core layer. However, the heavy pulverized product contains a larger amount of inorganic components than the light pulverized product and has high reactivity, so that it causes a good curing reaction with the cement. Immediately after production, almost 60% of the cement component remains as unreacted material, and the unreacted material is filled in the pores of the hardened cement matrix. Thus, when the unreacted material is filled in the pores of the hardened cement matrix, the dimensional stability of the wood cement board is deteriorated.
[0023]
In the present invention, the above heavy pulverized material is also filled in the pores of the cement hardened material matrix in the core layer, and the heavy pulverized material includes the hardened cement material that has finished the reaction in addition to the unreacted cement content. In addition, it is difficult for water or the like to enter the pores, and shrinkage and swelling are suppressed. Furthermore, since it reacts to some extent with the unreacted material remaining on the wood cement board in the pores, the dimensional stability of the wood cement board is greatly improved, and the reinforcement effect by the wood reinforcement material as well as the front and back layers is effective. Demonstrated.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
In this example, a waste material of a three-layered wood cement board produced by a dry method using raw materials having the following composition was used.
<Front and back layers>
Cement 47.5% by weight
Quartz sand 32.5 〃
Wood chips 14.5 〃
Wood flour 5.5 〃
Hardener 2.0 〃
<Core layer>
Cement 33.0 〃
Fly ash 22.0 〃
Wood chip 6.0 〃
Wooden fiber bundle 10.0 〃
Expandable polystyrene beads 2.0 〃
Hardener 2.0 〃
Reject 27.0 〃
Primary curing was performed at 70 ° C. for 10 hours, and autoclave curing was performed at 165 ° C. for 7 hours as a secondary curing.
The wood cement board waste was pulverized with a hammer mill to obtain a primary pulverized product having a particle size of 0.5 to 2.0 mm. Further, the primary pulverized product was secondarily pulverized by a roller mill, and a light pulverized product having a bulk specific gravity of 0.40 and a heavy pulverized product having a bulk specific gravity of 1.00 were obtained by air classification.
Samples 1 to 5 of the present invention, which are wood cement boards having a three-layer structure having a front and back layer portion and a core layer portion using a hydrated mixture obtained by adding 40 to 50% by weight of water to the mixture having the composition shown in Table 1, and comparison Sample 1 was prepared by a dry method.
[0025]
[Table 1]

[0026]
For the sample and the comparative sample, a predetermined amount of the mixture of the surface layer composition shown in Table 1 is sprayed on the lower mold plate to form the surface layer mat, and a predetermined amount of the mixture of the core layer composition shown in Table 1 is sprayed thereon. Then, the core layer portion mat is formed, and a predetermined amount of the mixture of the surface layer portion composition is sprayed thereon to form the back layer mat, and the upper mold plate is brought into contact therewith, and the surface pressure is 10 kgf / cm ² . Press compaction at 70 ° C., pre-curing for 10 hours, pressure 6 kgf / cm ² , temperature 165 ° C., auto-clave curing for 7 hours and drying to form a three-layer structure with weight ratio of front / back layer / core layer = 1/3 A wood cement board sample was prepared.
Various physical properties of each sample thus prepared were measured. The results are shown in Table 2.
[0027]
[Table 2]

[0028]
According to Table 2, Comparative Example 1 using only the primary pulverized material of the wood cement board waste material has lower strength than Examples 1 to 5 of the present invention using the lightly pulverized material and the heavy pulverized material. Is recognized.
[0029]
【The invention's effect】
In the present invention, in addition to adding a pulverized product by hammer mill pulverization of wood cement board waste material, a light pulverized product having an absolute dry specific gravity of 0.90 to 1.20 secondary pulverized by a roller mill is used as the front and back layers. Since a heavy pulverized product of 1.00 to 1.30 is added to the core layer, a wood cement board having high strength and good dimensional stability can be provided by effectively using a large amount of waste wood cement board. I can do it.

Claims

A wood cement board in which wood reinforcement is dispersed in a matrix of hardened cement,
It has a three-layer structure consisting of a front and back layer having a dense structure and a core layer having a rough structure,
The front and back layers have an absolute dry specific gravity of 0.90 to 1. 10 and further includes a lightly pulverized wood cement board waste material having a bulk specific gravity of 0.20 to 0.60 in an amount of 20% by weight or less,
The core layer has an absolute dry specific gravity of 1. A wood cement board characterized by comprising 10 to 1.30 , and further comprising a wood ground slab waste material heavy pulverized product having a bulk specific gravity of 0.80 to 1.20 in an amount of 40% by weight or less .

The wood cement board according to claim 1,
In the wood cement board , a piece of wood having a particle size of 4.5 mm or less and / or wood powder having a particle size of 0.5 to 1.5 mm is used as a wood reinforcing material for the front and back layers. ,
Further, as the wood reinforcing material of the core layer, a piece of wood having a particle size of 4.5 to 10 mm and / or a wood fiber bundle having an average diameter of 1.0 mm and a length of 20 mm are used .
It is manufactured by the dry method
A wood cement board characterized by that .

The wood cement board according to claim 1 or 2,
Wherein the wood cement board waste light ground product contains wood components 25 to 50 wt%,
Wherein the wood cement board waste heavy pulverized material contains inorganic components 60 to 90 wt%
A wood cement board characterized by that .

The wood cement board according to claim 1, 2, or 3,
The wood cement board waste light pulverized material and the wood cement board waste heavy grind, a wood cement board waste material subjected to primary pulverizing in a hammer mill, and the secondary pulverization further the primary grind at a roller mill, the secondary pulverized material It was obtained by classification with absolute dry gravity and bulk specific gravity ,
Is less than 1 [mu] m or more 1000 [mu] m particle size
A wood cement board characterized by that .

The woody cement board according to any one of claims 1 to 4,
The wood cement board waste light pulverized product and / or primary ground product of the wood cement board instead of a part of the wood cement board waste heavy pulverized material, 2 wt% or less in the front and back layers, 28 wt in core layer % Is added in the amount
A wood cement board characterized by that .