JP2004001357A

JP2004001357A - Composite wood and its manufacturing method

Info

Publication number: JP2004001357A
Application number: JP2002280845A
Authority: JP
Inventors: Katsuyuki Hasegawa; 長谷川　克之
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-09-28
Filing date: 2002-09-26
Publication date: 2004-01-08
Anticipated expiration: 2022-09-26
Also published as: JP3680172B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for composite wood constituted so as to use an arbitrary amount of wood and to simply manufacture a product enabling nailing and having an arbitrary shape. <P>SOLUTION: A molten binder resin and a plurality of wood pieces are kneaded and the kneaded matter of wood pieces and the binder resin is strongly pressed. In this state, the binder resin is cooled or strong pressing and cooling are repeated to cure the kneaded matter. The obtained composite wood is further cut into a plate shape having a predetermined thickness or a rod shape having a predetermined dimension and the cut wood members are assembled into a desired product. The water content of the wood pieces may be evaporated by the heat of the binder resin or may be evaporated by heating the wood pieces. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
この発明は複合木材及びその製造方法に関し、特に加工性等の木材としての優れた特性と、耐水性等の合成樹脂としての優れた特性を併有し、しかも所定の機械的強度を有する複合木材及びその製造方法に関する。
【０００２】
【従来の技術】
最近、環境問題が社会的に注目されているが、特に二酸化炭素による地球温暖化が現実的になりつつある今日、樹木の伐採による森林破壊が大きな問題となっきている。通常、木材は伐採された樹木を乾燥して製材し、各種の用途に応じた形状や構造に加工されるのが一般的であるが、最終的には焼却処分されることが多く、木材が有効に利用されていなかった。
【０００３】
他方、一般的に広く利用されているポリエチレンやポリプロピレン等のポリオレフィン系の熱可塑性樹脂は親油性を示し、親水性を示す木材、パルプ、紙、鋸屑等とは相互の濡れ性が悪いことから、上手く混ぜることができず、無理に混合しても相互の結合力が弱く、これらの複合材の製造は難しかった。
【０００４】
そこで、木質材料とフェノール樹脂やエポキシ樹脂等の熱硬化性樹脂とを用いてファイバーボード、パーティクルボード、木質ブロック等の複合材料を製造する方法が種々提案されているが、熱硬化性樹脂を使用する関係でコスト高になっていた。
【０００５】
これに対し、廃木材、間伐材あるいは木屑を木粉に粉砕し、木粉と溶融したポリオレフィン系の廃プラスチックとを混練し、押出し成形することにより製品とし、資源の有効利用を図る方法が提案されている（特許文献１、特許文献２、特許文献３、特許文献４、特許文献５、特許文献６、特許文献７、等参照）。
【０００６】
【特許文献１】特公昭５９−１３０４号公報
【特許文献２】特開昭５８−２１７５５２号公報
【特許文献３】特公昭５９−２４５５号公報
【特許文献４】特開昭５９−２１７７４４号公報
【特許文献５】特公平０３−６４５５３号公報
【特許文献６】特開昭６１−１５５４３６号公報
【特許文献７】特開平１０−７１６３６号公報
【０００７】
【発明が解決しようとする課題】
しかし、上記従来の木粉を用いる方法では複合木材の機械的性質を確保するためには木粉を乾燥して含有水分を所定量、例えば１０％以下にする必要があり、製造工程が複雑であった。
【０００８】
また、木粉の量を多くすると、溶融樹脂と上手く混練できず、実用的には木粉の量を合成樹脂材料の量に対して体積比で等倍程度までしか使用できていないのが実情である。
【０００９】
さらに、木粉を用いた複合材料であるというものの、実際には合成樹脂材料に似た物性を示し、釘の打ち込み鋸による切断あるいは水溶性接着剤による接着が難しく、適用できる製品用途が制限されるという問題もあった。
【００１０】
本発明はかかる問題点に鑑み、加工性等の木材としての優れた特性と、耐水性等の合成樹脂としての優れた特性を併有し、しかも所定の機械的強度を有する複合木材を製造できるようにした方法を提供することを課題とする。
【００１１】
【発明が解決しようとする課題】
そこで、本発明に係る複合木材は、複数の木片をバインダー樹脂によって相互に結合してなる複合木材であって、上記複数の各木片は相互に垂直な３方向において複数の微小腔の形態がほぼ残存するような立体的形状をなし、該複数の各木片の立体的形状の全体又は大部分はその表面側の微小腔を圧潰するように変形させた状態で上記バインダー樹脂によって包囲されるとともに、上記複数の各木片の表面側の微小腔には上記バインダー樹脂が入り込むことによって上記複数の木片と上記バインダー樹脂とが相互に結合されていることを特徴とする。
【００１２】
本発明の特徴の１つは複数の微小腔の立体的形態がほぼ残存するような形状の複数の木片をバインダー樹脂によって強加圧状態で相互に結合するようにした点にある。
【００１３】
これにより、複数の木片がバインダー樹脂によって囲まれて相互に分離されるので、断熱性が高く、又表面に露出した木片に水分が浸透しても水分はその木片のみにとどまり、他の木片まで浸透しないので、複合木材全体としては優れた耐水性能を発揮する。
【００１４】
また、複数の木片の表面側がバインダー樹脂の加圧によって表面側の微小腔を圧潰するように変形されるとともに、表面側の微小腔にバインダー樹脂が入り込むので、木片とバインダー樹脂とが相互に強固に結合され、例えば親水性を示す木片と親油性を示すオレフィン系樹脂等のバインダー樹脂とを強固に結合できる。従って、複合木材の表面に木片が露出しても簡単に剥離せず、複合木材を用いた製品の品質を保証できる。
【００１５】
さらに、多数の木片が分散して状態でバインダー樹脂によって結合されているので、木材に似た物性を示し、釘を簡単に打込むことができるとともに、鉋による削りができ、又物性に方向性がないので、複合木材のどのような部位であっても任意の方向に鋸で切断することができ、さらには複合木材の表面には木片が露出するので、かかる木片を利用して水溶性接着剤による接着もできる。
【００１６】
また、木片の量を任意に設定できるので、木片の量を多くし、木片同士を相互にほぼ連携し合った分散状態でバインダー樹脂によって結合すると、高い引っ張り強度及び高い曲げ強度等、高い機械的強度を示す。その結果、上述の断熱性及び耐水性に加え、木材に類似した物性、合成樹脂に類似した物性及び高い機械的強度を示すので、あらゆる用途、例えば型枠等の建築資材、柱や壁材等、家具の芯材、パレット等の運搬資材、ベンチ等の屋外品等に利用できる。
【００１７】
例えば、パレット等の運搬資材の場合、天然の木材を使用すると、荷受け国における森林被害を防止するため、松喰い虫等の害虫駆除のための燻蒸や熱処理を要求され、コスト高となる。これに対し、本発明においては合成樹脂中に木片を分散させた複合木材であるので、害虫駆除のために燻蒸や熱処理を要求されることはなく、複合木材を用いてパレット等の運搬資材を製作しても害虫駆除のためにコスト高を招来することはない。
【００１８】
さらに、木片はその周囲をバインダー樹脂によって取り囲まれ、木片の間は相互に分離されているので、使用中に松喰い虫等の害虫が複合木材の表面側の木片に取りついても内部まで侵入することもない。
【００１９】
木片を破砕機で破砕した場合、木材の繊維方向の端部がささくれた形態となる。このささくれ部分の形態に起因して木片とバインダー樹脂とを更に相互に結合することができる。
【００２０】
即ち、木片はその表面側の一部が複数のささくれた形状をなし、該複数のささくれた形状部分の間にはバインダー樹脂が入り込むとともに、複数のささくれた形状部分が相互に接近する方向に変形されることによって複数の木片とバインダー樹脂とが更に相互に結合されることができる。
【００２１】
ここで、木片とは相互に垂直な３方向において複数の微小腔の形態がほぼ残存するような立体的形状をなすものをいう。本発明では破砕機の櫛目の大きさで２ｍｍ以上の大きさを有するものをいい、木粉とは破砕機又は粉砕機の櫛目の大きさで２ｍｍ未満の大きさを有するものをいう。また、木材のスライス薄片とは相互に垂直な３方向のうちの２方向においてのみ複数の微小腔の形態がほぼ残存するような平面的形状をなすものをいう。
【００２２】
木片は相互に垂直な３方向において複数の微小腔の形態がほぼ残存するような立体的形状を有するという点で、微小腔の形態がほとんど残存しない木粉や垂直な３方向のうちの１方向において微小腔の形態がほとんど残存しない木材のスライス薄片と区別される。木片の微小腔とは主として細胞腔をいうが、導管腔や毛細管腔も含まれていてもよい。この点で本発明でいう木片は木粉や木材のスライス薄片と区別される。
【００２３】
廃木材等を破砕した場合、大きさの異なる木片や木粉が含まれているのが一般的である。従って、複数の木片は均一な大きさとしてもよいが、選別工程を省略すべく、大きさの異なる複数の木片をそのまま用いるのがよい。
【００２４】
また、複数の木片の間には破砕機の櫛目の大きさで２ｍｍ未満の大きさを有する木粉や相互に垂直な３方向のうちの２方向においてのみ複数の微小腔の形態がほぼ残存するような平面的形状をなす木材のスライス薄片が分散されていてもよい。
【００２５】
上述のように、バインダー樹脂と木片との高い結合強度を確保できるので、木片の量はバインダー樹脂の量に対して任意とすることができるが、実用的には木片の量はバインダー樹脂の量に対して体積比で１倍〜５倍とするのがよい。
【００２６】
また、バインダー樹脂はどのような樹脂でもよく、例えば一般的に広く用いられているポリプロピレン、ポリエチレン、ポリ塩化ビニル、その他の熱可塑性樹脂を使用するのがよい。
【００２７】
さらに、木片は新しい木材から得たものでもよいが、木材資源の有効利用という点を考慮すると、廃木材に由来するものを用いるのがよい。
【００２８】
また、熱可塑性樹脂には新しい樹脂を用いてもよいが、資源の有効活用という点を考慮すると、廃プラスチックに由来する樹脂を用いるのがよい。
【００２９】
さらに、本発明に係る複合木材はある用途に使用した後、従来と同様に廃棄処分することもできるが、熱可塑性樹脂を使用している関係上、使用済みの複合木材を加熱すると、熱可塑性樹脂が軟化溶融し、木片と熱可塑性樹脂とを混練した最初の状態に戻る。従って、本発明に係る複合木材は使用後に原料として何度でも再使用することができるという点で、リサイクル性に優れている。
【００３０】
即ち、複数の木片及び熱可塑性樹脂には使用済みの複合木材の破砕片に由来するものを全部又は一部に用いることができる。
【００３１】
また、本発明に係る複合木材の製造方法は、相互に垂直な３方向において複数の微小腔の形態がほぼ残存するような立体的形状をなす複数の木片がほぼ全体にわたって分散されるとともに相互に垂直な３方向のうちの少なくとも１方向に強加圧された状態でバインダー樹脂によって相互に結合されかつ上記複数の各木片は該複数の各木片の立体的形状の全体又は大部分の表面側の微小腔を圧潰するように変形させた状態で上記バインダー樹脂によって包囲されるとともに、上記複数の各木片の表面側の微小腔には上記バインダー樹脂が入り込むことによって上記複数の木片とバインダー樹脂とが相互に結合されてなる複合木材であって、該複合木材を製造するにあたり、木片を加熱して木片の含有水分を蒸発させるとともに、バインダー樹脂を溶融させて該溶融したバインダー樹脂と上記複数の木片とを混練し、上記木片とバインダー樹脂の混練物を相互に垂直な３方向あるいは該３方向のうちの２方向又は１方向に強加圧し、該強加圧状態を維持したまま冷却するか又は上記強加圧と冷却とを繰り返して上記バインター樹脂を硬化させるようにしたことを特徴とする。
【００３２】
本発明の特徴の１つは複数の微小腔の形態がほぼ残存するような立体的形状の複数の木片をバインダー樹脂と混練し、３方向、２方向又は１方向に強加圧し、その状態で冷却し、バインダー樹脂を硬化させるようにした点にある。
【００３３】
これにより、複数の木片の表面側の微小腔を圧潰するように変形させた状態でバインダー樹脂によって包囲するとともに、複数の各木片の表面側の微小腔にはバインダー樹脂が入り込むので、複数の木片とバインダー樹脂とが相互に強固に結合する。その結果、断熱性、耐水性、木材に類似した物性、合成樹脂に類似した物性、高い引っ張り強度や高い曲げ強度等の高い機械的強度を示す複合木材を製造することができる。
【００３４】
ここで、木片とバインダー樹脂との混練物を３方向に強加圧するとは、１面の開放した成形型に混練物を注入し、開放された１方向から加圧プレートによって強加圧するような場合をいい、型締め力以上の加圧力が加えられる点で通常の型成形と区別される。
【００３５】
混練物を１方向から強加圧するとは、混練物を混練機からプレート状に押し出し（混練機から押出し機に移して押出し機から押し出してもよい）、プレート状の混練物をローラで強加圧するような場合をいい、２方向から強加圧するとは縦ローラ及び横ローラで縦横から加圧するような場合をいう（縦ローラに代え、横ローラの両側に型部を設け、横ローラの強加圧力でもって混練物の両側の型部に押し付けて横方向からの強加圧を得るようにしてもよい）。
【００３６】
３方向に加圧する場合には成形型及び加圧プレートを水冷することによって混練物を強加圧状態のままで冷却することができる。しかし、２方向又は１方向に加圧する場合には３方向加圧の場合と同様の方法を採用できない。そこで、２方向又は１方向に加圧する場合における方法を種々検討し実験を繰り返したところ、強加圧と冷却とを繰り返す方法を採用すれば同様の結果が得られることが分かった。
【００３７】
木片の含有水分は溶融したバインダー樹脂との混練前に、他の熱源で加熱し含有水分を蒸発させるようにしてもよいが、溶融したバインダー樹脂と複数の木片とを混練する際に木片をバインダー樹脂の熱によって加熱して木片の含有水分を蒸発させるようにしてもよい。このようにすると、木片の乾燥工程を別途必要とせず、製造工程を簡素化できる。
【００３８】
使用済みの複合木材を再使用する場合、回収した複合木材を木片の立体的形状が残存する程度の大きさ、例えば一辺が２５ｍｍ〜３５ｍｍの大きさに破砕し、適当な熱源によって加熱して熱可塑性樹脂を溶融させ、必要に応じて熱可塑性樹脂を添加し、木片と熱可塑性樹脂の混練物の全部又は一部として用いるようにすればよい。
【００３９】
使用済みの複合木材を再使用する場合にも木片と熱可塑性樹脂の適切な比率を維持する必要がある。
【００４０】
【発明の実施の形態】
以下、本発明を図面に示す具体例に基づいて詳細に説明する。図１ないし図６は本発明に係る複合木材の好ましい実施形態を示し、これは運搬用パレットに適用した例である。図において、パレット１０は２本の角材１１、１１の間に、両角材１１を挟むように複数枚の板材１２・・・を並べて掛け渡し、板材１２・・・に釘を打ち込んで角材１１に固定して製作されている。
【００４１】
角材１１及び板材１２の素材には本例の複合木材が用いられている。この複合木材は図２に示されるように、多数の木片２０・・・をほぼ全体にわたって分散するとともに相互に直交する３方向に強加圧された状態でバインダー樹脂２１によって相互に結合して製造されている。
【００４２】
木片２０は廃木材や間伐材等に由来するものであって、破砕機の櫛目の大きさで２ｍｍ以上の大きさ、即ち相互に垂直な３方向において複数の微小腔の形態がほぼ残存するような立体的形状をなす大きさを有し、木片２０の間には２ｍｍ以下の木粉２２が適量分散されている。なお、木片２０は２ｍｍ以上の大きさであればよく、木片の原料や破砕方法あるいは複合木材の用途に応じて適宜選択すればよい。また、木粉に代え、あるいは木粉とともに木材のスライス薄片が分散されていてもよい。
【００４３】
また、バインダー樹脂２１には例えばポリプロピレン、ポリエチレンあるいはポリ塩化ビニル等、廃プラスチック（新品のプラスチックでもよい）に由来する熱可塑性樹脂が用いられている。融点の近い樹脂の場合には複数種を混合してもよいが、融点の相違による樹脂の劣化や特性のばらつきを考慮すると、単一で用いるのがよい。
【００４４】
木片２０の量はバインダー樹脂２１の量に対して体積比で１倍ないし５倍、例えば４．５倍となっている。なお、木片２０の量は複合木材を用いる用途によって適宜選択すればよく、その場合には１倍未満であってもよく、５倍を越える量としてもよい。例えば、バインダー樹脂の物性を主として利用した場合には木片２０の量をバインダー樹脂２１に対して１倍又はそれ以下とすればよく、木片の物性を主として利用したい場合には木片２０の量をバインダー樹脂２１に対して２倍又はそれ以上とすればよく、用途に応じて適宜選択することができる。
【００４５】
バインダー樹脂２１内に埋没した複数の各木片２０の表面側の全体は図３の（ａ）（ｂ）に示されるようにその表面側の微小腔を圧潰する方向に変形させた状態でバインダー樹脂２１によって包囲されるとともに、表面側の微小腔にはバインダー樹脂が入り込んでおり、該入り込んだバインダー樹脂がアンカーとして作用し、木片２０とバインダー樹脂２１とが強固に結合されている。
【００４６】
また、バインダー樹脂２１表面に露出した複数の各木片２０の表面側の大部分（樹脂側部分）は図３の（ｃ）（ｄ）（ｅ）に示されるようにその表面側の微小腔を圧潰する方向に変形させた状態でバインダー樹脂２１によって包囲されるとともに、複数の各木片２０の表面側（樹脂側）の微小腔にはバインダー樹脂が入り込んでおり、これによって木片２０とバインダー樹脂２１とが強固に結合されている一方、各木片２０の樹脂と反対側の表面は微小腔がそのまま露出しているので、水溶性接着剤が微小腔内に容易に侵入することができる。
【００４７】
さらに、木片２０の繊維方向の端部にささくれだった部分が存在する場合には図３の（ｆ）に示されるように、複数のさされくれた部分の間にバインダー樹脂が入り込むとともに、複数のさされくれた部分が相互に接近する方向に変形されており、これによって木片２０とバインダー樹脂２１とが更に結合されている。
【００４８】
なお、参考のために、木粉の立体的形状を図４に示すが、木粉では微小腔の形態がほとんど残存していない。
【００４９】
次に、図５及び図６を用いて製造方法について説明する。本例の複合木材を製造する場合、廃木材や間伐材を破砕機によって櫛目の大きさで２ｍｍ以上に破砕し、多量の木片２０と少量の木粉２２の混ざった材料を準備する一方、廃プラスチックに由来するバインダー樹脂、例えばポリプロピレン、ポリエチレンあるいはポリ塩化ビニルを破砕機によって適当な大きさのチップに破砕する。なお、これらは１種でもよく、複数種の混ざったものでもよい。
【００５０】
他方、混練機３０の加熱ヒータを作動させ、混練機３０内部をバインダー樹脂の溶融温度、例えば１００°Ｃ〜３００°Ｃまで上昇させておき、破砕したバインダー樹脂のチップを混練機３０内に投入し、攪拌しながら溶融させる。バインダー樹脂チップの投入は一度に行ってもよく、複数回に向けて分けて行ってもよい（図６のステップＳ１０）。
【００５１】
なお、バインダー樹脂の溶融中に攪拌羽根の回転による溶融樹脂の攪拌によって熱が発生する場合には加熱ヒータによる加熱温度はバインダー樹脂の溶融温度よりも多少低温であってもよい。
【００５２】
バインダー樹脂２１が十分に溶融すると、準備した木片２０と木粉２２を一度に又は複数回に分けて混練機３０内に投入し、溶融したバインダー樹脂２１が木片２０及び木粉２２の表面を確実にコーティングするように混練する（図６のステップＳ１１）。
【００５３】
なお、木片２０及び木粉２２は一度に大量に投入すると、溶融樹脂の温度が低下してしまうことがあるので、木片２０及び木粉２２を予め加熱ヒータ等で適当な温度に加熱するのがよい。
【００５４】
また、バインダー樹脂を溶融状態のままで長時間加熱すると、樹脂本来の物性が損なわれることもなるので、十分に溶融した後、短時間で混練を完了させるのが好ましい。本件発明者の実験によれば、溶融してから混練が完了するまでの時間は５分〜３０分程度が好ましいことが判明した。
【００５５】
また、混練の際、溶融樹脂の例えば１００°Ｃ〜３００°Ｃの高熱によって木片２０及び木粉２２が加熱され、木片２０及び木粉２２に含まれていた水分が蒸発し、混練機３０の開口から放散されるので、木片２０及び木粉２２の含有水分が大幅に減少する。なお、混練機３０が密閉形の場合には一定の時間間隔をあけて開放し、水蒸気を放散させるようにする。
【００５６】
また、溶融樹脂の高熱によって木片２０及び木粉２２が加熱されるので、木片２０及び木粉２２に含まれていた害虫や卵を全て死滅させることができる。
【００５７】
木片２０及び木粉２２と溶融したバインダー樹脂２１とが十分に混練されると、混練機３０の下方に成形用の下型３１をセットし、混練機３０内の混練物を下型３１内に投入する（図６のステップＳ１２）。
【００５８】
この下型３１をレール３５によってプレス機３２まで移動させ、プレス機３２にセットした上型３４で下型３１内の混練物を上方から強加圧、即ち通常の樹脂成型における型締め時の圧力よりも大きな圧力で加圧し、その状態で冷却し硬化させる（図６のステップＳ１３）。冷却を行う場合、上下の型３１、３４には水冷ジャケットを設けておき、混練物を強加圧状態のままで水冷するようにするのがよい。
【００５９】
プレス機３２は上型３４を複数の油圧シリンダ又はエアーシリンダで下降させ、各シリンダで１９．６×１０^−５Ｐａ（２０ｋｇｆ／ｃｍ^２）の面圧を加える構造となっている。なお、面圧は５８．８×１０^−５Ｐａ（６０ｋｇｆ／ｃｍ^２）程度まで複合木材の用途や材料等に応じて適宜設定すればよいが、必要に応じてそれよりも大きな面圧を加えることもできる。
【００６０】
所定時間が経過し、混練物が十分に硬化すると、上型３４を引き上げ、下型３１を取出し機３３まで移動させ、真空吸着等を利用して下型３１内の所定寸法のブロック状又は板状の複合木材４０を取り出し（図６のステップＳ１１４）、下型３１は混練機３０まで戻す。
【００６１】
取り出したブロック状又は板状の複合木材４０は鋸によって所定の厚みの板状又は所定の大きさの角材に切断し、これらを組み合わせて釘打ちすると、図１に示される複合木材からなるパレット１０を製造することができる。
【００６２】
また、使用済みのパレット１０、その他の複合木材の製品を回収し、再使用する場合には回収したパレット１０等を破砕機又は粉砕機によって櫛目の大きさで３０ｍｍ程度に破砕又は破砕し、これを混練機３０に投入し、必要に応じて木片又はバインダー樹脂を投入し、バインダー樹脂を混練機３０の加熱ヒータによって溶融させると、木片及び木粉とバインダー樹脂との混練物が得られるので、後は上記と同様にして新しいブロック状又は板状の複合木材を製造することができる。
【００６３】
以上のような本例の複合木材では多数の木片２０がバインダー樹脂２１によって囲まれて相互に分離されているので、断熱性が高く、又複合木材の表面に露出した木片２０に水分が浸透しても水分はその木片２０のみにとどまり、内部の木片２０まで浸透しないので、複合木材全体としては優れた耐水性能を発揮する。
【００６４】
本件発明者が常温水及び煮沸水の吸水試験を行ったところ、常温水の平均吸水率は天然木材が１．５〜２．７％であるのに対し、本例の複合木材では０．６％以下であった。また、煮沸水の平均吸水率は本例の複合木材では２．３％以下であった。いずれにしても本例の複合木材では天然木材に比してほとんど吸水が起こらず、吸水に起因する寸法変化も発生しないことが確認された。
【００６５】
また、本件発明者が木材としての物性を調べたところ、釘を簡単に打込むことができるとともに、鉋による削りができ、又複合木材のどのような部位であっても任意の方向に鋸で切断することができ、さらには水溶性接着剤による接着もできることが確認された。
【００６６】
さらに、本件発明者が機械的強度について調べたところ、木材よりも高い引っ張り強度及び高い曲げ強度等、高い機械的強度を示すことが確認された。
【００６７】
図７は第２の実施形態を示し、図において図５と同一符号は同一又は相当部分を示す。本例では２軸加圧押出し機５０（１軸加圧押出し機でもよい）が設けられ、バインダー樹脂のチップを２軸加熱押出し機５０の投入口に投入すると、内蔵の加熱ヒータによってバインター樹脂のチップが加熱されるとともに２つのスクリューによって前方に練られながら送られて更に昇温し、出口から十分に溶融したバインダー樹脂が送り出されるようになている。
【００６８】
本例のシステムを用いて複合木材を製造する場合、混練機３０に木片と木粉を一度に又は複数回に分けて投入し、混練機３０の加熱ヒータによって木片と木粉を加熱し、その含有水分を十分に蒸発させておく。他方、バインダー樹脂のチップを２軸加熱押出し機５０に投入し、バインダー樹脂を十分に溶融させて混練機３０に投入し、溶融したバインダー樹脂が木片及び木粉の表面を確実にコーティングするように混練する。その後は、第１の実施形態と同様に、混練物を成形用の下型３１を投入し、プレス機３２にセットした上型３４で下型３１内の混練物を上方から強加圧しながら冷却し、硬化すると取り出せばよい。
【００６９】
図８は第３の実施形態を示し、図において図５及び図７と同一符号は同一又は相当部分を示す。混練機３０の前方には２軸加熱押出し機６０（１軸加熱押出機であってもよい）が設けられ、２軸加熱押出し機６０の押出し口にはダイ７０が取り付けられている。ダイ７０の前方には複数の受けプレート７１が長手方向に並べて設けられ、隣接する受けプレート７１の間には一対の横ローラ８０が設けられ、最終の横ローラ８０の前方には切断機９０が設けられている。
【００７０】
本例のシステムを用いて複合木材を製造する場合、バインダー樹脂のチップを混練機３０に投入して溶融させた後、木片と木粉を一度に又は複数回に分けて投入し、バインダー樹脂と木片及び木粉とを混練する。その際、溶融したバインダー樹脂の熱によって木片と木粉を加熱し、その含有水分を十分に蒸発させる。
【００７１】
混練物が十分に混練されると、混練物を混練機３０から２軸加熱押出し機７０の投入口に投入し、２軸加熱押出し機６０によって練りながら前方に送られ、ダイ７０からプレート状に押し出される。すると、混練物には２軸加熱押出し機６０及びダイ７０内において周囲から大きな加圧力が作用し、複数のうちの幾つかの木片の表面側の微小腔が潰されるように変形され、微小腔にバインダー樹脂が侵入する。
【００７２】
混練物がダイ７０からプレート状に押し出されると、混練物は受けプレート７１上を前方に送られ、周囲から冷却エアーが次々と吹きつけられ、温度が徐々に低下する。また、受けプレート７１上を前方に送られたプレート状の混練物は複数の横ローラ８０によって上下方向に繰り返し強加圧され、こうして複数の木片の表面側の微小腔が潰されるように変形され、微小腔にバインダー樹脂が侵入する。横ローラ８０の加圧力は第１の実施形態における加圧力と同程度となるように設定する。
【００７３】
プレート状の混練物が最終の横ローラ８０を通過すると、冷却エアーの作用によって所定の温度まで低下し、プレート状の混練物は十分に硬化し、最後に切断機９０によって所定の長さに切断されてプレート状の複合木材が得られる。なお、最後の横ローラ８０は加熱ヒータを内蔵し、プレート状の複合木材の表面を平滑にする機能を持たせてもよい。
【００７４】
本例の複合木材はダイ７０から押し出された後に前方に送られながら上下に強加圧されるので、複数の木片が送り方向に整列した状態でバインダー樹脂によって結合されている。従って、上記送り方向に沿う方向の曲げに対しては高い耐曲げ性を示すことが確認された。
【００７５】
なお、本発明は上記の製造方法に限定されず、他の方法を採用することもできる。例えば、製品形状の成形型を用い、製品を成型するようにしてもよい。また、上下、左右及び高さの３方向のうちの２方向から加圧を行うようにすることもできる。
【００７６】
また、複合木材の用途はパレットに限定されず、他の製品、例えば合板等の建築用資材、柱材等の建築材料、家具の芯材やベンチ等の耐久消費材に利用することもできる。
【図面の簡単な説明】
【図１】本発明に係る方法の好ましい実施形態によって製造された複合木材を用いたパレットを示す概略斜視図である。
【図２】上記複合木材を示す一部断面図である。
【図３】上記複合木材における顕微鏡写真を示す図である。
【図４】木粉の顕微鏡写真を示す参考図である。
【図５】上記実施形態の製造方法を概念的に示す概略図である。
【図６】上記実施形態における製造工程を示す工程図である。
【図７】第２の実施形態の製造方法を概念的に示す概略図である。
【図８】第３の実施形態の製造方法を概念的に示す概略図である。
【符号の説明】
１０　　　　パレット
２０　　　　木片
２１　　　　バインダー樹脂
２２　　　　木粉
３０　　　　混練機
３１　　　　下型
３２　　　　プレス機
３３　　　　取出し機
３４　　　　上型
４０　　　　複合木材板
５０　　　　２軸加熱押出し機
６０　　　　２軸加熱押出し機
７０　　　　ダイ
８０　　　　横ローラ
９０　　　　切断機[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a composite wood and a method for producing the same, and more particularly to a composite wood having both excellent properties as wood such as processability and excellent properties as a synthetic resin such as water resistance, and having a predetermined mechanical strength. And its manufacturing method.
[0002]
[Prior art]
Recently, environmental issues have attracted public attention, and today, especially as global warming due to carbon dioxide is becoming more realistic, deforestation by cutting down trees has become a major problem. In general, timber is usually dried and sawn, and processed into shapes and structures according to various uses.However, wood is ultimately incinerated in many cases. It was not used effectively.
[0003]
On the other hand, polyolefin-based thermoplastic resins such as polyethylene and polypropylene, which are generally widely used, exhibit lipophilicity, and have poor wettability with wood, pulp, paper, sawdust, etc., which exhibit hydrophilicity. It was not possible to mix well, and even if it was forcibly mixed, the mutual bonding strength was weak, and it was difficult to produce these composite materials.
[0004]
Therefore, various methods have been proposed for producing composite materials such as fiberboards, particle boards, and wood blocks by using a wood material and a thermosetting resin such as a phenol resin or an epoxy resin. Cost was high due to the relationship.
[0005]
On the other hand, a proposal has been made to pulverize waste wood, thinned wood or wood chips into wood flour, knead wood flour with molten polyolefin waste plastic, extrude it into a product, and make effective use of resources. (See Patent Literature 1, Patent Literature 2, Patent Literature 3, Patent Literature 4, Patent Literature 5, Patent Literature 6, Patent Literature 7, etc.).
[0006]
[Patent Document 1] Japanese Patent Publication No. 59-1304
[Patent Document 2] JP-A-58-217552
[Patent Document 3] Japanese Patent Publication No. 59-2455
[Patent Document 4] JP-A-59-217744
[Patent Document 5] Japanese Patent Publication No. 03-64553
[Patent Document 6] JP-A-61-155436
[Patent Document 7] JP-A-10-71636
[0007]
[Problems to be solved by the invention]
However, in the conventional method using wood flour, it is necessary to dry the wood flour to a predetermined amount, for example, 10% or less, in order to secure the mechanical properties of the composite wood, and the manufacturing process is complicated. there were.
[0008]
In addition, if the amount of wood powder is increased, it cannot be kneaded well with the molten resin, and in practice, the amount of wood powder can only be used up to about 1 times the volume ratio of the synthetic resin material. It is.
[0009]
Furthermore, although it is a composite material using wood flour, it shows physical properties similar to a synthetic resin material, and it is difficult to cut with a nail driving saw or bond with a water-soluble adhesive, which limits the applicable product applications. There was also a problem that.
[0010]
In view of the above problems, the present invention can produce composite wood having both excellent properties as wood such as processability and excellent properties as a synthetic resin such as water resistance, and having a predetermined mechanical strength. It is an object to provide such a method.
[0011]
[Problems to be solved by the invention]
Therefore, the composite wood according to the present invention is a composite wood in which a plurality of pieces of wood are joined to each other by a binder resin, and each of the plurality of pieces of wood has a shape of a plurality of minute cavities in three mutually perpendicular directions. Form a three-dimensional shape as remaining, while the entire or most of the three-dimensional shape of each of the plurality of wood pieces is surrounded by the binder resin in a state deformed to crush the micro-cavities on the surface side, The plurality of wood pieces and the binder resin are connected to each other by the binder resin entering the microcavities on the surface side of the plurality of wood pieces.
[0012]
One of the features of the present invention is that a plurality of pieces of wood having such a shape that the three-dimensional shape of a plurality of microcavities is almost left are bonded to each other by a binder resin under a strong pressure.
[0013]
As a result, a plurality of pieces of wood are surrounded by the binder resin and separated from each other, so that the heat insulating property is high, and even if water penetrates into the pieces of wood exposed on the surface, the water remains only in the pieces of wood and extends to other pieces of wood. Since it does not penetrate, it exhibits excellent water resistance performance as a whole composite wood.
[0014]
In addition, the surface of the plurality of pieces of wood is deformed so as to crush the microcavities on the surface side by pressing the binder resin, and the binder resin enters the microcavities on the surface side. And, for example, a wood chip having hydrophilicity and a binder resin such as an olefin-based resin having lipophilicity can be strongly bonded. Therefore, even if a piece of wood is exposed on the surface of the composite wood, it does not easily peel off, and the quality of the product using the composite wood can be guaranteed.
[0015]
Furthermore, since a large number of pieces of wood are dispersed and joined by a binder resin, they show physical properties similar to wood, and can be easily driven with nails, can be sharpened by a plane, and have directivity in physical properties. Because there is no, it can be cut in any direction at any part of the composite wood with a saw, and furthermore, since the wood piece is exposed on the surface of the composite wood, water-soluble bonding using such wood piece Adhesion with an agent is also possible.
[0016]
In addition, since the amount of wood pieces can be arbitrarily set, the amount of wood pieces is increased, and when the wood pieces are joined together by a binder resin in a dispersed state almost cooperatively with each other, high mechanical strength such as high tensile strength and high bending strength is obtained. Indicates strength. As a result, in addition to the above-mentioned heat insulation and water resistance, it exhibits physical properties similar to wood, physical properties similar to synthetic resin, and high mechanical strength, so that it can be used in all applications, such as building materials such as formwork, columns and wall materials, etc. It can be used for core materials of furniture, transportation materials such as pallets, and outdoor goods such as benches.
[0017]
For example, in the case of a transport material such as a pallet, if natural wood is used, fumigation or heat treatment for controlling pests such as pine worms or the like is required in order to prevent forest damage in the receiving country, which increases costs. On the other hand, in the present invention, since it is a composite wood in which wood pieces are dispersed in a synthetic resin, fumigation or heat treatment is not required for controlling pests, and transport materials such as pallets using the composite wood are used. Even if it is manufactured, it does not incur high costs for pest control.
[0018]
Furthermore, the wood pieces are surrounded by a binder resin, and the wood pieces are separated from each other, so that even if pests such as pine worms are attached to the wood pieces on the surface side of the composite wood during use, they enter the interior. Not even.
[0019]
When a piece of wood is crushed by a crusher, the end of the wood in the fiber direction becomes crooked. Due to the form of the raised portion, the wood chip and the binder resin can be further bonded to each other.
[0020]
That is, a part of the surface of the wood piece has a plurality of raised shapes, a binder resin enters between the plurality of raised shapes, and the plurality of raised shapes deforms in a direction approaching each other. By doing so, the plurality of pieces of wood and the binder resin can be further bonded to each other.
[0021]
Here, a piece of wood refers to a piece having a three-dimensional shape such that a plurality of micro-cavities almost remain in three mutually perpendicular directions. In the present invention, a crusher having a comb size of 2 mm or more is referred to, and wood flour refers to a crusher or a crusher having a comb size of less than 2 mm. A slice of wood refers to a slice having a planar shape in which a plurality of microcavities almost remain in only two directions out of three directions perpendicular to each other.
[0022]
The wood piece has a three-dimensional shape such that a plurality of microcavities almost remain in three mutually perpendicular directions. One of the three directions is wood flour or the vertical three directions in which the microcavities hardly remain. Is distinguished from a slice of wood in which the microcavity morphology hardly remains. The microcavities of a piece of wood mainly refer to cell cavities, but may also include conduit cavities and capillary cavities. In this regard, the wood chips referred to in the present invention are distinguished from wood flour and wood slices.
[0023]
When crushed waste wood and the like, it is common to include wood chips and wood flours of different sizes. Therefore, the plurality of pieces of wood may have a uniform size, but it is preferable to use a plurality of pieces of wood having different sizes as they are in order to omit the sorting step.
[0024]
In addition, between a plurality of pieces of wood, wood flour having a size of less than 2 mm in the size of a comb of a crusher and a plurality of micro-cavities almost remain only in two directions among three directions perpendicular to each other. Slices of wood having such a planar shape may be dispersed.
[0025]
As described above, since the high bonding strength between the binder resin and the wood piece can be ensured, the amount of the wood piece can be arbitrarily set with respect to the amount of the binder resin. The volume ratio is preferably 1 to 5 times.
[0026]
The binder resin may be any resin, and for example, generally used polypropylene, polyethylene, polyvinyl chloride, and other thermoplastic resins may be used.
[0027]
Further, the wood chips may be obtained from new wood, but in view of effective use of wood resources, it is preferable to use wood chips derived from waste wood.
[0028]
Although a new resin may be used as the thermoplastic resin, it is preferable to use a resin derived from waste plastic in consideration of effective use of resources.
[0029]
Furthermore, after the composite wood according to the present invention is used for a certain purpose, it can be disposed of in the same manner as in the past.However, due to the use of a thermoplastic resin, when the used composite wood is heated, it becomes thermoplastic. The resin softens and melts, and returns to the initial state where the wood chips and the thermoplastic resin are kneaded. Therefore, the composite wood according to the present invention is excellent in recyclability in that it can be reused as a raw material any number of times after use.
[0030]
That is, as the plurality of wood pieces and the thermoplastic resin, those derived from crushed pieces of used composite wood can be used in whole or in part.
[0031]
Further, in the method for producing composite wood according to the present invention, a plurality of pieces of wood having a three-dimensional shape such that a plurality of microcavities almost remain in three directions perpendicular to each other are dispersed over substantially the entirety and mutually. The plurality of wood pieces are mutually bonded by a binder resin in a state of being strongly pressed in at least one of three perpendicular directions, and the plurality of wood pieces are all or most of the three-dimensional shape of the plurality of wood pieces on the surface side. While being surrounded by the binder resin in a state where the cavity is deformed so as to be crushed, the plurality of wood pieces and the binder resin are mutually interspersed by the binder resin entering the microcavities on the surface side of each of the plurality of wood pieces. The composite wood which is bonded to, when producing the composite wood, while heating the wood pieces to evaporate the water content of the wood pieces, the binder resin The melted binder resin is kneaded with the plurality of wood pieces, and the kneaded product of the wood pieces and the binder resin is strongly pressed in three mutually perpendicular directions or two or one of the three directions. The present invention is characterized in that the binder resin is cooled while maintaining the strong pressurized state or the strong pressurization and the cooling are repeated to cure the binder resin.
[0032]
One of the features of the present invention is that a plurality of three-dimensionally shaped pieces of wood, in which a plurality of microcavities are almost left, are kneaded with a binder resin, strongly pressed in three, two, or one direction, and cooled in that state. And the binder resin is cured.
[0033]
As a result, the microcavities on the surface side of the plurality of wood pieces are surrounded by the binder resin in a deformed state so as to be crushed, and the binder resin enters the microcavities on the surface side of each of the plurality of wood pieces. And the binder resin are firmly bonded to each other. As a result, it is possible to produce a composite wood exhibiting heat insulation, water resistance, physical properties similar to wood, physical properties similar to synthetic resin, and high mechanical strength such as high tensile strength and high bending strength.
[0034]
Here, the case where the kneaded material of the wood piece and the binder resin is strongly pressed in three directions means that the kneaded material is poured into an open mold on one side and strongly pressed by a pressing plate from one opened direction. In other words, it is distinguished from normal molding in that a pressing force greater than the clamping force is applied.
[0035]
When the kneaded material is strongly pressed from one direction, the kneaded material is extruded from the kneader into a plate shape (the kneaded material may be transferred from the kneader to the extruder and extruded from the extruder), and the plate-shaped kneaded material is strongly pressed with a roller. The strong pressure from two directions means the case where pressure is applied vertically and horizontally by the vertical roller and the horizontal roller (instead of the vertical roller, mold parts are provided on both sides of the horizontal roller, and the strong pressure of the horizontal roller is applied. It may be pressed against the molds on both sides of the kneaded material to obtain strong pressure from the lateral direction).
[0036]
In the case of pressing in three directions, the kneaded material can be cooled in a strongly pressurized state by cooling the mold and the pressing plate with water. However, when pressing in two directions or one direction, the same method as in the case of pressing in three directions cannot be adopted. Thus, various methods in the case of pressing in two directions or one direction were examined and the experiment was repeated. As a result, it was found that a similar result could be obtained by employing a method in which strong pressing and cooling were repeated.
[0037]
Before kneading with the molten binder resin, the water content may be heated by another heat source to evaporate the water content. You may make it heat by the heat of resin and evaporate the water content of a piece of wood. This eliminates the need for a separate wood chip drying step and simplifies the manufacturing process.
[0038]
When the used composite wood is reused, the recovered composite wood is crushed to a size such that the three-dimensional shape of the piece of wood remains, for example, a size of 25 mm to 35 mm on a side, and heated by a suitable heat source to heat it. The thermoplastic resin may be melted, a thermoplastic resin may be added as necessary, and the mixture may be used as a whole or a part of a kneaded product of the wood chip and the thermoplastic resin.
[0039]
When reusing used composite wood, it is necessary to maintain an appropriate ratio of wood chips and thermoplastic resin.
[0040]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail based on specific examples shown in the drawings. 1 to 6 show a preferred embodiment of a composite wood according to the present invention, which is an example applied to a transport pallet. In the figure, a pallet 10 has a plurality of plate members 12 arranged side by side between two square members 11, 11 so as to sandwich both square members 11, and nails the plate members 12. It is fixed and manufactured.
[0041]
The composite wood of this example is used as the material of the square lumber 11 and the plate 12. As shown in FIG. 2, this composite wood is manufactured by dispersing a large number of wood pieces 20... Almost all over and bonding them together with a binder resin 21 while being strongly pressed in three mutually orthogonal directions. ing.
[0042]
The wood piece 20 is derived from waste wood, thinned wood, etc., and has a comb size of a crusher of 2 mm or more, that is, a form in which a plurality of micro-cavities almost remain in three mutually perpendicular directions. A suitable amount of wood flour 22 having a size of 2 mm or less is dispersed between the wood pieces 20. The size of the wood piece 20 may be 2 mm or more, and may be appropriately selected according to the material of the wood piece, the crushing method, or the use of the composite wood. In addition, wood slices may be dispersed in place of wood flour or together with wood flour.
[0043]
Further, as the binder resin 21, a thermoplastic resin derived from waste plastic (new plastic may be used) such as polypropylene, polyethylene or polyvinyl chloride is used. In the case of resins having similar melting points, a plurality of resins may be mixed, but it is preferable to use a single resin in consideration of resin degradation and characteristic variations due to differences in melting points.
[0044]
The amount of the wood piece 20 is 1 to 5 times, for example, 4.5 times the volume ratio of the amount of the binder resin 21. The amount of the wood pieces 20 may be appropriately selected depending on the use of the composite wood. In that case, the amount may be less than 1 time or may be more than 5 times. For example, when the physical properties of the binder resin are mainly used, the amount of the wood pieces 20 may be set to be one time or less than that of the binder resin 21, and when the physical properties of the wood pieces are mainly used, the amount of the It may be twice or more than that of the resin 21 and can be appropriately selected according to the application.
[0045]
As shown in FIGS. 3A and 3B, the entire surface of each of the plurality of wood chips 20 buried in the binder resin 21 is deformed in a direction to crush the micro-cavities on the surface thereof as shown in FIG. While being surrounded by 21, a binder resin enters the microcavity on the surface side, and the entered binder resin acts as an anchor, and the wood piece 20 and the binder resin 21 are firmly bonded.
[0046]
In addition, most of the surface side (resin side portion) of each of the plurality of wood pieces 20 exposed on the surface of the binder resin 21 has a small cavity on the surface side as shown in (c), (d), and (e) of FIG. While being surrounded by the binder resin 21 in a state of being deformed in the crushing direction, the binder resin enters the microcavities on the surface side (resin side) of each of the plurality of wood pieces 20, whereby the wood piece 20 and the binder resin 21 are formed. Are firmly connected, while the micro-cavities are exposed as they are on the surface of each piece of wood 20 opposite to the resin, so that the water-soluble adhesive can easily enter the micro-cavities.
[0047]
Furthermore, when there is a portion that has been squeezed at the end of the wood piece 20 in the fiber direction, as shown in FIG. The parts that have been removed are deformed in a direction approaching each other, whereby the wood pieces 20 and the binder resin 21 are further bonded.
[0048]
In addition, for reference, the three-dimensional shape of the wood flour is shown in FIG.
[0049]
Next, a manufacturing method will be described with reference to FIGS. In the case of manufacturing the composite wood of this example, waste wood and thinned wood are crushed by a crusher to a comb size of 2 mm or more to prepare a material in which a large amount of wood pieces 20 and a small amount of wood flour 22 are mixed, and A binder resin derived from plastic, for example, polypropylene, polyethylene or polyvinyl chloride is crushed into chips of an appropriate size by a crusher. These may be one kind or a mixture of a plurality of kinds.
[0050]
On the other hand, the heater of the kneader 30 is operated to raise the inside of the kneader 30 to the melting temperature of the binder resin, for example, 100 ° C. to 300 ° C., and the chips of the crushed binder resin are put into the kneader 30. And melt while stirring. The loading of the binder resin chip may be performed at once, or may be performed separately for a plurality of times (step S10 in FIG. 6).
[0051]
When heat is generated by the stirring of the molten resin due to the rotation of the stirring blade during the melting of the binder resin, the heating temperature of the heater may be slightly lower than the melting temperature of the binder resin.
[0052]
When the binder resin 21 is sufficiently melted, the prepared wood chip 20 and the wood powder 22 are put into the kneader 30 at once or divided into a plurality of times, and the melted binder resin 21 ensures the surfaces of the wood chip 20 and the wood powder 22. (Step S11 in FIG. 6).
[0053]
When a large amount of the wood chips 20 and the wood powder 22 are put in at once, the temperature of the molten resin may decrease. Therefore, it is necessary to heat the wood chips 20 and the wood powder 22 to an appropriate temperature in advance by a heater or the like. Good.
[0054]
In addition, if the binder resin is heated in a molten state for a long time, the physical properties of the resin may be impaired. Therefore, it is preferable that the kneading be completed in a short time after sufficient melting. According to the experiment of the present inventor, it was found that the time from melting to completion of kneading is preferably about 5 to 30 minutes.
[0055]
Further, at the time of kneading, the wood chip 20 and the wood flour 22 are heated by the high heat of the molten resin, for example, 100 ° C. to 300 ° C., and the moisture contained in the wood chip 20 and the wood flour 22 evaporates. Since the water is released from the openings, the water content of the wood chips 20 and the wood flour 22 is significantly reduced. When the kneading machine 30 is of a closed type, the kneading machine 30 is opened at regular time intervals so as to emit water vapor.
[0056]
Moreover, since the wood chip 20 and the wood flour 22 are heated by the high heat of the molten resin, all the pests and eggs contained in the wood chip 20 and the wood flour 22 can be killed.
[0057]
When the wood pieces 20 and the wood powder 22 and the molten binder resin 21 are sufficiently kneaded, a lower mold 31 for molding is set below the kneader 30 and the kneaded material in the kneader 30 is placed in the lower mold 31. It is inserted (step S12 in FIG. 6).
[0058]
The lower mold 31 is moved to the press machine 32 by the rail 35, and the kneaded material in the lower mold 31 is strongly pressed from above by the upper mold 34 set on the press machine 32, that is, from the pressure at the time of mold clamping in the ordinary resin molding. Is also pressurized with a large pressure, and cooled and cured in that state (Step S13 in FIG. 6). When cooling, the upper and lower dies 31, 34 are preferably provided with a water-cooling jacket, and the kneaded material is preferably water-cooled while being kept in a strongly pressurized state.
[0059]
The press 32 lowers the upper mold 34 by a plurality of hydraulic cylinders or air cylinders, and each cylinder 19.6 × 10 ^-5 Pa (20 kgf / cm ² ) Is applied. The surface pressure was 58.8 × 10 ^-5 Pa (60kgf / cm ² ) May be set as appropriate according to the use and material of the composite wood, but a greater surface pressure can be applied if necessary.
[0060]
After the predetermined time has elapsed and the kneaded material has sufficiently hardened, the upper mold 34 is pulled up, the lower mold 31 is moved to the unloader 33, and a block or plate of a predetermined size in the lower mold 31 is used by vacuum suction or the like. The composite wood 40 in the shape of is taken out (step S114 in FIG. 6), and the lower mold 31 is returned to the kneader 30.
[0061]
The block-shaped or plate-shaped composite timber 40 taken out is cut into a plate-shaped or timber having a predetermined thickness by a saw, and when these are combined and nailed, a pallet 10 made of the composite timber shown in FIG. Can be manufactured.
[0062]
In addition, used pallets 10 and other composite wood products are collected, and when reused, the collected pallets 10 and the like are crushed or crushed to a comb size of about 30 mm by a crusher or a crusher. Is put into the kneading machine 30, and if necessary, a piece of wood or a binder resin is added, and the binder resin is melted by the heater of the kneading machine 30, so that a kneaded product of wood chips and wood powder and the binder resin is obtained. Thereafter, a new block-shaped or plate-shaped composite wood can be manufactured in the same manner as described above.
[0063]
In the composite wood of the present embodiment as described above, a large number of wood pieces 20 are surrounded by the binder resin 21 and are separated from each other, so that the heat insulation property is high, and moisture penetrates into the wood pieces 20 exposed on the surface of the composite wood. However, since the water stays only in the wood piece 20 and does not penetrate into the wood piece 20 inside, the composite wood as a whole exhibits excellent water resistance.
[0064]
When the present inventor conducted a water absorption test at room temperature and boiling water, the average water absorption of room temperature water was 1.5 to 2.7% for natural wood, and 0.6% for composite wood of this example. % Or less. The average water absorption of boiling water was 2.3% or less in the composite wood of this example. In any case, it was confirmed that the composite wood of this example hardly absorbed water as compared with natural wood, and no dimensional change due to the water absorption occurred.
[0065]
In addition, when the present inventor examined the physical properties of wood, it was found that nails could be easily driven into the wood, sharpened by a plane, and any part of the composite wood could be sawed in any direction. It was confirmed that it could be cut, and that it could be bonded with a water-soluble adhesive.
[0066]
Further, when the present inventor examined the mechanical strength, it was confirmed that the present invention exhibited high mechanical strength such as higher tensile strength and higher bending strength than wood.
[0067]
FIG. 7 shows a second embodiment, in which the same reference numerals as in FIG. 5 denote the same or corresponding parts. In this example, a twin-screw extruder 50 (a single-screw extruder may be used) is provided. When a chip of the binder resin is put into the inlet of the twin-screw extruder 50, a binder heater for the binder resin is introduced by a built-in heater. The chip is heated and fed while being kneaded forward by two screws to further raise the temperature, so that a sufficiently melted binder resin is sent out from the outlet.
[0068]
When manufacturing composite wood using the system of the present example, the wood chips and wood flour are put into the kneader 30 at once or divided into a plurality of times, and the wood chips and wood flour are heated by the heater of the kneader 30. The water content is sufficiently evaporated. On the other hand, the chips of the binder resin are put into the twin-screw extruder 50, and the binder resin is sufficiently melted and put into the kneader 30, so that the molten binder resin coats the surfaces of the wood chips and the wood powder without fail. Knead. Thereafter, as in the first embodiment, the lower mold 31 for molding the kneaded material is charged, and the kneaded material in the lower mold 31 is cooled while being strongly pressed from above by the upper mold 34 set on the press machine 32. , Should be taken out after curing.
[0069]
FIG. 8 shows a third embodiment, in which the same reference numerals as those in FIGS. 5 and 7 denote the same or corresponding parts. A twin-screw extruder 60 (may be a single-screw extruder) is provided in front of the kneader 30, and a die 70 is attached to an extrusion opening of the twin-screw extruder 60. A plurality of receiving plates 71 are provided in front of the die 70 in a longitudinal direction, a pair of horizontal rollers 80 are provided between adjacent receiving plates 71, and a cutting machine 90 is provided in front of the final horizontal roller 80. Is provided.
[0070]
When manufacturing composite wood using the system of the present example, after the chips of the binder resin are put into the kneader 30 and melted, the wood chips and the wood powder are put at once or divided into a plurality of times, and the binder resin and Knead the wood chips and wood flour. At that time, the wood chips and the wood powder are heated by the heat of the molten binder resin, and the water content is sufficiently evaporated.
[0071]
When the kneaded material is sufficiently kneaded, the kneaded material is fed from the kneader 30 to the input port of the twin-screw extruder 70, fed forward while being kneaded by the twin-screw extruder 60, and formed into a plate shape from the die 70. Extruded. Then, a large pressing force acts on the kneaded material from the surroundings in the twin-screw extruder 60 and the die 70, and the kneaded material is deformed so that the microcavities on the surface side of some of the pieces of wood are crushed, and the microcavities are formed. Binder resin penetrates into the resin.
[0072]
When the kneaded material is extruded in a plate shape from the die 70, the kneaded material is sent forward on the receiving plate 71, and cooling air is blown from the surroundings one after another, so that the temperature gradually decreases. Further, the plate-shaped kneaded material sent forward on the receiving plate 71 is repeatedly strongly pressed in the vertical direction by the plurality of horizontal rollers 80, and is thus deformed so that the microcavities on the surface side of the plurality of wood pieces are crushed, Binder resin penetrates into the microcavities. The pressing force of the horizontal roller 80 is set to be substantially the same as the pressing force in the first embodiment.
[0073]
When the plate-shaped kneaded material passes through the final horizontal roller 80, the temperature is lowered to a predetermined temperature by the action of cooling air, and the plate-shaped kneaded material is sufficiently hardened, and finally cut to a predetermined length by a cutting machine 90. Thus, a plate-shaped composite wood is obtained. The last horizontal roller 80 may have a function of smoothing the surface of the plate-shaped composite wood by incorporating a heater therein.
[0074]
Since the composite wood of this example is strongly pressed up and down while being pushed forward after being extruded from the die 70, a plurality of pieces of wood are joined by a binder resin in a state of being aligned in the feeding direction. Therefore, it was confirmed that the material exhibits high bending resistance against bending in the direction along the feed direction.
[0075]
Note that the present invention is not limited to the above manufacturing method, and other methods can be adopted. For example, the product may be molded using a product-shaped mold. In addition, pressure can be applied from two directions among three directions of up, down, left, right, and height.
[0076]
Further, the use of composite wood is not limited to pallets, but it can be used for other products, for example, building materials such as plywood, building materials such as pillars, and durable consumption materials such as furniture core materials and benches.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view showing a pallet using composite wood manufactured by a preferred embodiment of the method according to the present invention.
FIG. 2 is a partial sectional view showing the composite wood.
FIG. 3 is a view showing a micrograph of the composite wood.
FIG. 4 is a reference diagram showing a micrograph of wood flour.
FIG. 5 is a schematic view conceptually showing the manufacturing method of the embodiment.
FIG. 6 is a process chart showing a manufacturing process in the embodiment.
FIG. 7 is a schematic view conceptually showing a manufacturing method according to a second embodiment.
FIG. 8 is a schematic view conceptually showing a manufacturing method according to a third embodiment.
[Explanation of symbols]
10 pallets
20 pieces of wood
21 Binder resin
22 Wood flour
30 kneading machine
31 Lower mold
32 press machine
33 Take-out machine
34 Upper type
40 composite wood board
50 twin screw extruder
60 twin screw extruder
70 die
80 horizontal roller
90 cutting machine

Claims

A composite wood made by bonding a plurality of wood pieces to each other with a binder resin,
Each of the plurality of pieces of wood has a three-dimensional shape such that the form of a plurality of microcavities almost remains in three mutually perpendicular directions, and the entire or most of the three-dimensional shape of each of the plurality of pieces of wood is on the surface side thereof. While being surrounded by the binder resin in a state of being deformed to crush the microcavities, the plurality of wood chips and the binder resin by the binder resin enters the microcavities on the surface side of each of the plurality of wood chips. Composite wood characterized by being bonded to each other.

A part of the surface of the wood piece has a plurality of raised shapes, and the binder resin enters between the plurality of raised shapes, and a direction in which the plurality of raised shapes approach each other. The composite wood according to claim 1, wherein the plurality of pieces of wood and the binder resin are further bonded to each other by being deformed.

The composite wood according to claim 1 or 2, wherein the plurality of wood pieces have a comb size of a crusher of 2 mm or more.

Between the plurality of pieces of wood, wood flour having a size of less than 2 mm in the size of the comb of the crusher and / or the form of a plurality of minute cavities almost remains only in two of three mutually perpendicular directions. The composite wood according to any one of claims 1 to 3, wherein sliced slices of wood having a planar shape as described above are dispersed.

The composite wood according to any one of claims 1 to 4, wherein the amount of the plurality of wood chips is 1 to 5 times the volume of the binder resin by volume.

The composite wood according to any one of claims 1 to 5, wherein the binder resin is polypropylene, polyethylene, polyvinyl chloride, or another thermoplastic resin.

The composite wood according to any one of claims 1 to 6, wherein the plurality of wood pieces are derived from waste wood.

The composite wood according to any one of claims 1 to 7, wherein the thermoplastic resin is a resin derived from waste plastic.

The composite wood according to any one of claims 1 to 8, wherein the plurality of wood pieces and the thermoplastic resin are derived from crushed pieces of used composite wood.

A plurality of pieces of wood having a three-dimensional shape such that a plurality of microcavities almost remain in three mutually perpendicular directions are dispersed over substantially the entirety, and strongly pressurized in at least one of the three mutually perpendicular directions. The plurality of wood pieces are connected to each other by a binder resin in a state in which they are formed, and the plurality of wood pieces are deformed so as to crush the entire or most of the surface-side microcavities of the three-dimensional shape of each of the plurality of wood pieces. A composite wood, which is surrounded by a resin, and wherein the plurality of pieces of wood and the binder resin are mutually bonded by entering the binder resin into the microcavities on the surface side of each of the plurality of pieces of wood. In producing wood,
Heating the wood piece to evaporate the water content of the wood piece, melting the binder resin and kneading the melted binder resin and the plurality of wood pieces,
The kneaded product of the wood chip and the binder resin is strongly pressurized in three directions or one direction perpendicular to each other, and is cooled while maintaining the strongly pressurized state or the strong pressurization and cooling are repeated to cure the binder resin. A method for producing composite wood, characterized in that:

The method for producing composite wood according to claim 10, wherein when kneading the melted binder resin and the plurality of wood pieces, the wood pieces are heated by the heat of the binder resin to evaporate the water content of the wood pieces.

The method for producing composite wood according to claim 10 or 11, wherein the used composite wood according to any one of claims 1 to 9 is crushed and reused as a material of the plurality of wood pieces and the thermoplastic resin.