JP4258689B2 - Buffer material and manufacturing method thereof - Google Patents

Description

【００３１】
以上の原料を用いた接着剤４の製造方法を以下に述べる。まず、表１に示すこれら原料を均一に混合した後、例えばポリエチレンテレフタレートやアルミ箔などの耐熱性と柔軟性を有するシートの上に薄く散布し、これを９０℃に保持した乾燥機中で１０分間の乾燥処理を行って、アセトンの除去と予備反応を進行させる。得られた接着剤は非常に脆くて容易に粉砕できる状態にあるから、必ずしも粉砕を行う必要が無く、このまま用いても良い。
【００３２】
次に、緩衝材の製造方法を図４の工程図及び図５の成形方法の説明図に基づいて説明する。図５（ａ）は成形方法の説明図であり、２２は不織布、４０は発泡樹脂の粉砕物３と接着剤４との混合物、４２は下金型、４３は上金型である。
図５（ｂ）は成形した後の状態を示すもので、４１は緩衝層、２２ａは不要となる不織布、Ｐは受圧面である。
【００３３】
まず、回収した発泡ポリスチレンは、回転刃を有して切断するなどして微細化させる粉砕器を用いて、直径が５ｍｍ以下、好ましくは２ｍｍ程度の平均粒径を有する大きさに粉砕する（Ｓ−１）。次いで、ドラム式の混合機に粉砕物３と接着剤４の粉末の所定量を投入して混合する（Ｓ−２）。得られた混合物４０を、不織布２２を下金型形４２状に沿って載置した（Ｓ−３）下金型４２内に、所定量を緻密で均一な状態になるように整えながら投入した（Ｓ−４）。ここで使用される下金型４２では受圧面Ｐが形成される形状となっている。
【００３４】
次に、混合物４０の上に不織布２２を載置し、この上に上金型４３を載せて混合物４０に１ｋｇ／ｃｍ²以下、好ましくは０．２ｋｇ／ｃｍ²の圧縮応力を付加した（Ｓ−５）。この時の上金型４３の温度は発泡ポリスチレンの熱変形温度に至らずに接着剤の融点である７０℃よりも高い８０℃に調整しておき、一方の下金型４２の温度は発泡ポリスチレンの熱変形温度以上である１４０℃に調整した。上金型４３を載置後、１０分間の加温状態で保持して成形（Ｓ−６）して接着剤を硬化させた。その後、室温まで冷却させて取り出した（Ｓ−７）。このときの状態は図５（ｂ）に示すように不要となる不織布２２ａが残っているので、これを切断して仕上げて緩衝材２１を得た。
【００３５】
以上のようにして得られた成形した緩衝材２１には、接着剤として高濃度のアミン系触媒を含んで成るエポキシ樹脂を用いているので、室温雰囲気にあっても反応は徐々に進行して完全硬化に至り、高熱変形温度の緩衝材が得られる。このため、その後の使用においては、本来の緩衝材である発泡ポリスチレンの使用温度を上回る１１０℃の熱変形温度を有するので、本実施の形態で得られた緩衝材２１の使用温度を下げる必要はない。
【００３６】
また、接着剤として半硬化状態のエポキシ樹脂を用いて発泡ポリスチレンの粉砕物３同士を保持するようにしたので、特別な工夫を要さない金型を用いても表面が平滑でボイドなどの空隙を含み難い構造である緩衝材２１を得ることができた。併せて、緩衝材として強い衝撃力を受けた場合に、粉砕物とそれらを接合する剛性の高いエポキシ樹脂の界面付近で破壊して変形を来すことによって吸収するので、柔軟で反発力の高い発泡ポリスチレンを用いていても衝撃の反発力を受けず、優れた緩衝特性を呈することができる。
【００３７】
また、外装に用いた不織布２２によって、接着剤４が完全硬化に至らず、強固な接着力が生じないので、脆い性質である期間内、発泡ポリスチレンの粉砕物３が欠落するという問題を回避することができる。一方、ここで用いた外装材は、繊維を非直線で無秩序な配向状態で保持して成る不織布状を成す柔軟な多孔質のシートであるから、不十分な金型への配設によって金型表面に当接することの無い状態であっても、繊維が多方向に渡って容易にずれるとともに直線状に延びる挙動を備えるので、応力の付加に対して広がりの変形を呈する距離に裕度もあるから、容易に破れることなく、シート状態を保持して緩衝層４１の表面と一体化することができる。さらに、ここで用いた外装材の不織布２２は、燃焼させても有害なガスを発生することが殆ど無いので、処置が簡易である。
【００３８】
また、緩衝材２１の受圧面Ｐに相当する部位を形成する下金型４２の温度を粉砕物３を構成する発泡ポリスチレンの熱変形温度以上に高くしたので、粉砕物３を構成する発泡ポリスチレンの樹脂部分が軟化して成型時の圧縮でセルが変形して潰れるので、高密度となり剛直な層を形成する。ここに機器などを載置し、さらにこれが衝撃力を受けた場合に、この剛直な層がその下部にある粉砕物に架かる応力を分散させる作用を醸し出すので、局部的に大きな付加を受けることなく、従って成形した緩衝材２１を変形し難くすることができる。
【００３９】
なお、本実施の形態では、接着剤として半硬化状態のエポキシ樹脂を用いたが、これに替えて発泡ポリスチレンの粉砕物の気泡形状を大きく損なうことなく接合する上で好適な融点（室温〜８５℃、好ましくは６０〜７０℃）を有する熱可塑性樹脂、例えばＥＶＡ（エチレン−酢酸ビニル共重合体）樹脂を用いても良い。
【００４０】
実施の形態２．
本実施の形態は、本発明の請求項１〜９および１１に係るものであり、以下、図示の実施形態に基づき説明する。本実施の形態における緩衝材の構成は実施の形態１の図１、２と同じであるので説明は省略する。緩衝材の製造方法については、成形で使用する金型も実施の形態１と同じなので、図６の製造工程図及び図５の成形方法の説明図を用いて説明する。
【００４１】
本実施の形態で用いる発泡樹脂の粉砕物は、図７に示す構造の冷蔵庫の断熱箱体２６を粉砕した後、外殻を構成する内箱２３と外箱２４とともに外殻の内部にある断熱材２５である発泡ウレタンを、遠心分離作用を生じさせる気流内（サイクロン分級機等）に投入すれば、他の構成物よりもはるかに低比重の軽い物質として容易に分別、回収することができる。
【００４２】
本発明においては、十分な緩衝特性を得る上で、図８の概念図に示す粉砕した断熱材２５の気泡構造のように、セル膜２７によって仕切られて独立した気泡を有するものを用いることが好ましい。また、このような構造を備えるとともに分解または熱変形を来し難い樹脂で構成されていることが必要であり、このような発泡樹脂としては、熱硬化性樹脂である発泡ウレタンが最も汎用であり、冷蔵庫の断熱壁以外に建材用の軽量断熱構造板から回収したものであってもよい。
【００４３】
製造方法は、まず、以上に述べた断熱箱体から得た断熱材を実施の形態１と同様にして回転刃を有する粉砕器を用いて、粉砕物の直径が発泡材の気泡の大きさ（直径）の３倍以上で、かつ、直径が１０ｍｍ以下、好ましくは２ｍｍ程度の平均粒径を備える大きさに粉砕する。なお、気泡の直径は１００〜３００ミクロンである（Ｓ−１）。次いで、ドラム式の混合機に粉砕物３と接着剤４の粉末の所定量を投入して混合する（Ｓ−２）。得られた混合物４０は、予め不織布２２を下金型の形状に沿って載置した（Ｓ−３）下金型４２内に所定量をほぼ均一な状態に投入した（Ｓ−４）。
【００４４】
接着剤の構成として実施の形態１と異なる点は、硬化温度を発泡ウレタンの熱変形温度である９６℃よりも十分に高い１３０℃で１０分間の加熱を行うことである。この加熱条件の変更に伴って、接着剤の取り扱いを容易なものにするための組成として、表２の如く、エポキシ樹脂の触媒であるイミダゾールを減量して反応速度を低下させることと溶剤を安全性の高いメチルセルソルブに変更した。
さらに、溶剤の種類を変更したことに伴って、乾燥処理と予備反応を進行のための恒温槽中での加熱条件を１２０℃で１０分間に変更した。
【００４５】
【表２】

【００４６】
発泡ウレタンの粉砕物３を混合したときに、接着剤である半硬化状態のエポキシ樹脂は非常に脆くて容易に粉砕され、微粉末状態を呈するとともに、接着剤及び発泡ウレタンの粉砕物３が帯電するので、粉砕物３の表面に上述した接着剤である半硬化状態のエポキシ樹脂の粉末が静電付着に供する。このとき、接着剤である半硬化状態のエポキシ樹脂の量は、ほぼ同重量を添加することで十分に得ることができ、さらに、発泡樹脂の粉砕物の表面に吸着しない余剰の半硬化状態エポキシは、成型時に下方位置にある下金型４２の表面近傍の空隙を少なくして剛性の高い層を形成するのに活用できるので、排除する必要が無く、そのまま投入しておけばよい。
【００４７】
次に、前記工程で得られた発泡樹脂の粉砕物３と接着剤４の混合物４０を下金型４２内の容積（Ｌ）に対する投入量は、下記の式（１）によって求めたＶである。
【００４８】
αＶ＝Ｗ１／Ｄ１＋Ｗ２／Ｄ２ ・・・ （１）
Ｗ ＝Ｗ１＋Ｗ２ ・・・・・・・・ （２）
ここで、 Ｗ ；発泡樹脂の粉砕物４と接着剤の混合物の投入量（ｇ）
α ；過剰充填率
Ｖ ；金型内空隙の容積（Ｌ）
Ｗ１；発泡樹脂粉砕物の混合物中重量（ｇ）
Ｄ１；発泡樹脂の密度（ｇ／Ｌ）
Ｗ２；接着剤の混合物中重量（ｇ）
Ｄ２；接着剤の密度（ｇ／Ｌ）
【００４９】
上記の式によれば、αが１の場合には発泡樹脂が圧縮されて収縮することなく粉砕物４同志が完全に密着して断熱層を形成して成る状態を指す。また、αを１より大きくすれば、過剰の圧縮変形を付与するので、実使用時において変形し難い状態が確保できる。
【００５０】
ここで用いた断熱材の粉砕物は、図８の概念図に示す粉砕した断熱材２５の気泡構造のように隣り合うセルが発泡樹脂を構成する樹脂の薄膜である隔壁２７によって個々が連通した構造を有して成り、その直径は１００〜３００ミクロンの大きさである。このようなセルの構造において、機器などの製品の載置や輸送時にかかる衝撃力などの応力付加に対抗する強度は、その殆どが、３個以上のセルが隣接する接線部分に生成された柱状部分２８によって支えられるラーメン構造要素によるものである。この柱状部分２８の挫屈変形などの破壊に影響される圧縮強度としては、冷蔵庫の断熱材の場合で１．５〜２．０ｋｇ／ｃｍ²である。
【００５１】
しかし、外殻にある不織布２２内に充填した粉砕物の粒子が接する部分では受圧面が小さいことに併せて粉砕に伴う構造上の欠陥（セルの柱状部分２８の端部の支えがない状態）を備える粉砕物の表面同士が当接しているので容易に挫屈変形を来す状態にあり、粉砕物を散布したのみでは強度の大きな低下を招き、緩衝材として使用に耐えうる強度を発現することが困難である。従って、（１）式におけるαは載置する製品の重量に応じた強度を得るためには１より大きくすることが肝要であり、発泡ウレタン粉砕物の粒径に応じて（粒径に占める端部の支えがないセルの柱状部分２８の長さの比）、αを１．０５〜２．０に設定することが好ましく、１．２〜１．５が特に好ましい。
【００５２】
次に、発泡樹脂の粉砕物と接着剤の混合物４０を投入した下金型４２に対して微振動を付与する（Ｓ−５）。これによって、粉砕物が安定位置に納まるように適度に上下方向に移動して最密な状態で充填されると共に、比重差によって各々の原料の浮沈する速度の差異によって、比重が小さい発泡樹脂、特に粒径の大きな粉砕物が最も上方向に浮き上がり、最も比重の大きな接着剤を備えた粒径の小さな粉砕物３が沈み込む。従って、下金型４２は緩衝材２１の受圧面が下方位置になるようにすることによって、接着剤を多く含んだ粒径の小さい発泡樹脂の粉砕物３の組成物が受圧面近傍に多く集まって強固な層を形成するとともに、過度の接着剤を表面に付着しない粒径の大きな粉砕物が対向する面近傍に多く集積して発泡樹脂の粉砕物３の粒子間に連続した空隙を確保できるようになる。
【００５３】
次に、混合物４０の上に不織布２２を載置し、この上に上金型４３を載せて混合物４０に１kg/ｃｍ2以下、好ましくは０.２kg/ｃｍ2の圧縮応力を付加した（Ｓ−６）。この時の上金型４３の温度は発泡ポリウレタンのセルが破泡に至らずに接着剤の融点である７０℃よりも高い１２０℃に調整しておき、一方の下金型４２の温度は発泡ウレタンの熱変形温度以上の破泡を来す１４０℃に調整した。上金型４３を載置後、１０分間の加温状態で保持して成形（Ｓ−７）して接着剤を硬化させた。その後、室温まで冷却させて取り出した（Ｓ−８）。
【００５４】
ここで外装に用いた不織布２２は脆い緩衝層４１の表面を保護するとともに、繊維を非直線で無秩序な配向状態で保持して成る不織布状を成す柔軟な多孔質のシートであるから、容易に破れることなしにシート状態を保持して金型形状に十分に沿って緩衝層４１の表面と一体化することができる。さらに、この不織布２は、燃焼させても有害なガスを発生することが殆ど無いので、使用後の焼却処置が簡易である。
【００５５】
また、成型時（Ｓ−７）の下金型４２の温度は、発泡ウレタンの熱変形温度以上で破泡を来し、かつ、熱分解に至らない温度が行うことが好ましい。例えば、冷蔵庫の断熱材に用いていたものであれば８５〜１００℃、建材用の芯材に用いていたものであれば９０〜１２０℃の熱変形温度であるから、分解温度である２００〜３００℃よりもはるかに低い１１０〜１６０℃の任意の温度で行うことが好ましい。
【００５６】
ここで示す発泡ウレタンの熱変形温度とは、熱力学的分析装置（ＴＭＡ）を用いて、直径が３ｍｍで厚さが５ｍｍの円柱に５ｇの荷重を押し当てて寸法を測定した結果として図９に示した温度と寸法変化の関係図にて示すように、急激な寸法変化を示す特定温度（ａ点）である例を意味し、さらに、その温度よりも高温度域（ｂ点）である１２４℃以上では、風船が急激に膨らんだ後に破裂を来すように、独立した構造の気泡が急激に膨張してセル膜の破壊（破泡）に至るので、寸法の急激な増加と減少を繰り返す現象が観察されている。つまり、発泡ウレタンにおける一部の気泡が破壊されて連通化した部分を備えた緩衝材２１を得たことになる。
【００５７】
ここで用いた発泡ウレタンの粉砕物３は、独立した構造を有して成るセル構造であるから、使用時の高温下でセル内にあるガスが膨張して変形を来したり、低温下では逆に収縮を来すことがある。しかし、発泡樹脂の粉砕物３は高温状態で保持されて強度が低下した状態にあるので、この加温によるセル内ガスの膨張および加圧による圧縮変形によって内圧が上昇するので、極めて薄い樹脂膜で形成された隔壁が破壊されて連通化する。独立したセルの一部が連通化したことによって、セル内にあるガスが、高温時の膨張するときに系外に排出するなどして外気と同じ圧力に維持することによって断熱壁体の寸法膨張を抑制できるとともに、搬送時の衝撃による圧縮変形時にセル内にある空気などのガスを排出して過度な反発力の発生も抑制できる。
【００５８】
また、接着剤は加圧前に溶融状態に至っているので粉砕物の表面に濡れやすく、より大きな接着面積を確保し易い状態にあるので、成型時の圧縮によって発泡樹脂の粉砕物３同志の接触面が増すときに充分な濡れを確保して強固に結合できる。併せて、加圧による圧縮によってセル内ガスが排出されるので、これを系内に留まらせることなく、円滑に系外に排出するよう、金型にガス抜きを設ければ、得られた緩衝材２１の内部にボイドなどの欠陥部を生成することがなく、従って、平滑な外観と緩衝材２１に均一な圧縮特性を確保できるので、好ましい。
【００５９】
また、このような方法によって粉砕した発泡ウレタンの破泡を伴う高温で接着剤としての機能を有し、緩衝材の成形に寄与しうるものとしては、パラフィン系、アミド系などのホットメルト型接着剤を用いることも有効である。熱可塑性の樹脂を備えた発泡樹脂の粉砕物を接着するためには、これらホットメルト型の接着剤を用いて、粉砕物３が溶融などの永久的な変形を来すこと無しに十分な接着性を得るためには発泡樹脂の熱変形温度よりも相当に低い融点のものしか使用できないという制約を生む。
【００６０】
このことは、反面、接着剤を発泡樹脂の粉砕物と混合する時に、前記発泡樹脂の表面に粉砕物３同志の摩擦によって発生する静電気を利用して粉末状態で粉砕物３の表面に付着させる上で、低温状態を維持して行う必要があるなどの製造設備上での工夫が必要であることを示唆する。しかし、本態様による熱硬化性樹脂の発泡樹脂を用いて高温での接着を可能とせしめる方法においては、室温状態においても十分に粉末状態を維持できるホットメルト型の接着剤を用いることができる。
【００６１】
もし、ここで用いる発泡樹脂の粉砕物が発泡ポリスチレンなどの熱可塑性樹脂を備える場合、発泡樹脂が変形しない低温での溶融によって十分に固化させることによって粉砕物３が溶融などの永久的な変形を来さないようにして発泡状態が維持できる接着剤４を用いることが肝要であり、半硬化状態のエポキシ樹脂のほかにも、得られた緩衝材２１の使用可能温度が低い用途である場合にはＥＶＡ（エチレン−酢酸ビニル共重合体）樹脂等の発泡樹脂の熱変形温度よりも相当に低い融点のものを用いることも有効である。ただし、前述したような発泡樹脂の連通化を達成することが困難であるので、前述した発泡ウレタンに比較して緩衝特性が劣る反面、実施の形態１で述べたような受圧面を形成する金型の温度を高くして剛直な面を形成する手段として併用すれば、受圧面に製品を設置した部分に集中して受けた荷重を分散さる効果が増すので、変形を抑制できる。
【００６２】
なお、本実施の形態では、図６の製造工程示すように振動付与（Ｓ−５）を、上金型４３を載置（Ｓ−６）の前としたが、発泡樹脂の粉砕物３と接着剤４の混合物４０の充填率が大きいときは、混合物４０が下金型４２から溢れる場合があるので、図１０に示すように振動付与を、上金型４３を載置した後に行うか、または、下金型４２を混合物４０が溢れないような構造とする。
【００６３】
【実施例】
以下は、本実施の形態を有効とするために行った具体例を示すものであり、本発明の請求項７〜９および１１に係り、請求項１〜６の緩衝材の緩衝効果を確認したものである。
【００６４】
実施例１〜５
実施例１〜５の製造方法は図５の成形方法および図１０の製造工程図に基づいて行った。まず、冷蔵庫の断熱材で気泡の大きさ（直径）が１５０〜２００ミクロンである発泡ウレタンを回収し、回転刃を有する粉砕器をにて粉砕し、得られた粉砕物を、０．６〜１０ｍｍの大きさのものに分別、回収して用いた。そして、表３に示すように実施例１では粉砕物の大きさが０．６〜３ｍｍ、実施例２、４では１〜５ｍｍ、実施例３、５は３〜１０ｍｍのものを各々用いた。（Ｓ−１）。
【００６５】
【表３】

【００６６】
その後、実施例１〜３は、表２に示す融点が６５℃の半硬化状態の熱硬化性樹脂であるエポキシ樹脂である接着剤、実施例４、５は融点が６０℃で１００ミクロン以下の粉末にしたアミド系のホットメルト型接着剤を前記粉砕物の１００重量部に対して３０重量部を投入し、接着剤が発泡ウレタンの粉砕物に均一に付着するまで、室温で混合した（Ｓ−２）。
【００６７】
その後、図１に示す如くの外観で、幅が５８０ｍｍ、高さが７０ｍｍ、幅が５０ｍｍの大きさを有する緩衝材２１が得られる下金型４２に不織布２２を下金型４２の形状に沿って載置し（Ｓ−３）、その金型の内に工程Ｓ−２で得られた混合物４０を均一で密な状態で投入した（Ｓ−４）。この時の充填量は、受圧面に高い剛性を備える層を保持できるように、発泡樹脂の粉砕物３である発泡ウレタンと接着剤４であるエポキシ樹脂との混合物４０の見かけの密度に対し、発泡樹脂の粉砕物３の小粒径のものが多く、大粒径のものが少ない傾向にあるものの、約１．４倍の平均密度になるような緩衝材２１が得られる投入量を設定した。
【００６８】
次に、不織布状を成す柔軟な多孔質のシートである不織布２２を載置し、０．２ｋｇ／ｃｍ²の圧縮応力を付加できるように調整した上金型４３を載せ、上下金型４３、４２の合わせ面が製品厚さの１０〜２０％の隙間となるようにした。本実施例では２５ｍｍ程度の均一な隙間となった。（Ｓ−５）。さらに、密閉状態にあるこの上下金型４３、４２微振動を与えた（Ｓ−６）。
【００６９】
ここで、上金型４３を載置すると、混合物４０に当接して圧縮するので、その後の微振動によって混合物４０が上下に運動して好適な粒度分布をもたらすことができなくなる。このため、上金型４３は下金型４２にわずかに挿入された状態で保持されて、混合物３に当接することの無いように保持した。また、このときの振動付与は、振動の速度と距離、および時間を調整することによって最適な条件とした結果、下金型４２の上側に粒度が大きくて最小限の接着剤を保持した混合物、受圧面のある下方向に小さな粒度で接着剤を多量に含む混合物がほぼ、層状を成して形成された。
【００７０】
このようにして、下金型４２で適度な粒度と配合比の分布を得た発泡ウレタンと接着剤の粉砕混合物３に上金型４３を載置して５０℃／分以上の速度で１３０℃まで昇温して１０分間の保持をした後、上下金型４３、４２を密着させて１０分間の保持により接着剤を硬化させて成形をした（Ｓ−７）。成形完了後、室温まで冷却させて取り出す（Ｓ−８）ことによって成形した緩衝材２１を得た。
【００７１】
このときの上下金型４３、４２を密着させた状態は、前述したように２５ｍｍ程度の均一な隙間ができるが、１３０℃までの昇温と１０分間の保持の間に、接着剤が溶融と粉砕物の粒子が金型重量の付加による加圧によるクリープ変形によって上下金型４３、４２が当接する部位の隙間が１５ｍｍ程度にまで上金型４３が沈み込む。この状態で上下金型４３、４２を完全に閉じるまで更なる加圧を付与するので、構造上の欠陥部分を含むセルを多く含む受圧面近傍の粒径の小さな粉砕物が有する発泡状態の多くの部分が潰され、高密度になるとともに、粉砕物の粒子同志が接して形成された空隙を接着に寄与しない過剰の接着剤が埋めた層を形成する。
【００７２】
比較例１
実施例４の粉砕物と接着剤の性状を備えた混合物を用いて、発泡樹脂として発泡ポリスチレンを用い、前記実施例と同条件にて成形を行って得た緩衝材を比較例１とした。
【００７３】
比較例２、３
同様にして、実施例２と実施例４に示す粉砕物と接着剤の性状を備えた混合物を用い、接着剤の融点よりもわずかに高い成形温度である８０℃での金型温度で成形を行って得た緩衝材において、前者を比較例２、後者を比較例３とした。なお、いずれの接着剤を用いた場合であっても、金型内での保持時間はエポキシ樹脂が硬化して緩衝材の形状保持に十分な強度を備えたと思われる２５分間とした。
【００７４】
比較例４、５
表２に示す融点が６５℃である半硬化状態の熱硬化性樹脂であるエポキシ樹脂である接着剤を備えたもので、粉砕物の大きさが０．５ｍｍ以下（比較例４）または平均直径１５ｍｍ（比較例５）のものを用いて、他は前述した実施例と同じ成型の方法を用いて緩衝材を得た。
【００７５】
評価内容は以下のとおりである。
（１）緩衝材の重量
得られた緩衝材の重量を求めた。いずれの緩衝材においても、表皮を形成する不織布の重量の試料間での差異は非常に小さいので、同一重量である４ｇを差し引いた重量を採用した。
【００７６】
（２）外観意匠性
外観の平滑性を目視にて比較した結果を外観意匠性とし、粉砕前に発泡ポリスチレンで成形された本来の緩衝材を基準に５段階のレベルを付けて、ボイドなどによる表面の平滑性、粉砕物の固化状態の均一性、形状の再現性（収縮発生など）について評価した。
【００７７】
（３）圧縮特性
緩衝材として好ましい特性は低強度で高剛性を有するものである。この両特性の構成によれば、付加された応力が緩衝材に永久歪みを形成するので反発力を蓄積することがなくなり、衝撃力を吸収することができる。具体的には、成形した緩衝材の表面層を含む任意の位置から５０×５０ｍｍの受圧面と３０ｍｍの厚さを有する試料を裁断して採取し、これについて、１０ｍｍ／ｍｉｎ の速度で圧縮した場合の応力と歪みの関係曲線を求めた。この曲線の安定して変形する領域にある１０％歪時における付加応力と受圧面積から強度を、変形初期の直線的に応力が上昇する領域における変形の速度と受圧面積からと剛性を、各々、求めた。
【００７８】
（４）表面層の剛性
緩衝材の表面には不織布によって表皮が形成されているときに、過剰の接着剤と微粉砕物から成る剛直な層を得ており、これと接する粉砕物の接着剤による固化状態が十分でない場合に、付加応力が当接した直下の部分に集中して大きな変形、つまり、凹みを来すことになる。これに対して、十分な固化状態が得られれば、応力が付加された周辺に分散することができ、小さな変形に止まるので、繰り返しの応力や衝撃力への耐力が増す。従って、表面層の剛性は、先端がＲ５ｍｍの球状を成す３５０ｇの荷重を有するプラグの侵入量によって求めた。具体的には、前記装置を緩衝材上の任意の場所に載置し、１分後におけるダイヤルゲージの変化量から侵入量を読みとることとした。実施例１〜５、比較例１〜５の各試料について、以上の各種測定を行った結果を表４に示す。
【００７９】
【表４】

【００８０】
以上の通り、本発明による緩衝材の成形方法によれば、接着剤の硬化温度を粉砕物である発泡ウレタンの熱変形温度である９６℃よりも十分に高い１３０℃で行うことによって、気泡内にある発泡ガスが膨張して気泡膜が破壊するので、圧縮変形に反発する気泡内のガスが系外に排出されて強度に寄与しなくなること、また発泡構造体内に欠陥が生じて破壊の原因となる部分が生まれることで、緩衝材として好ましい低強度で高剛性のものが得られたと推測する。さらに、この時の発泡ガスの膨張によって、金型の合わせ面に１０ｍｍの隙間が形成される過剰な充填状態を加圧するときに発生する圧力に付加して前記ガスの膨張圧力が、熱変形温度以上になって柔軟な状態の粉砕物にさらにしかも均一に付加されるので、金型形状を転写できた優れた外観を有し、しかも表面層が高い剛性を保持した緩衝材を得ることができた。
【００８１】
これに対して、比較例１の発泡ポリスチレンの粉砕物を用いたものでは、型内の高温雰囲気下で発泡ポリスチレンが溶融を伴って収縮する傾向を持つために金型の内圧を十分に確保できず、金型表面に滞留したガスを系外に排出できず、多くのボイド状の凹部を形成した好ましくない外観状態と、残存する独立した気泡を保持したままであるから、強度の低下を招くことができなかった。
【００８２】
さらに、比較例２、３に関しても同様に、破泡を招き得ない低い成形温度であったので、強度の低下を得ることができず、緩衝材として好ましくない圧縮特性と脆さを有するものしか得ることができなかった。
【００８３】
また、比較例４では気泡径に対する粉砕物の大きさが小さすぎて、金型への投入に過剰量を必要としたにもかかわらず、接着剤との接合に十分な状態が得られず、従って、表４に示す表面層に剛性測定のプラグが過度に侵入し、非常に脆い緩衝材となった。反面、比較例５の１０ｍｍを超える非常に大きな粒径の粉砕物を用いた場合には、粉砕物の投入が十分に密な状態で行うことができずに表面に平滑な状態を得ることができず、しかも、粉砕した発泡ウレタンの粒子の中央まで破泡が及び難くなって、適度な強度低下を招くことができなかった。
一方、実施例１では、気泡の大きさが１５０〜２００ミクロンで、粉砕物の大きさが最小０．６〜３ｍｍであるので、気泡の大きさの３．０〜２０倍である。そして、この実施例１は、表面層が高い剛性を保持することができた。
従って、発泡樹脂粉砕物は、発泡樹脂の気泡の３倍以上で、かつ１０ｍｍ以下の直径のものを用いることが好ましいことが確認された。
【００８４】
以上のように、発泡ウレタンの適度な大きさの粉砕物を用いることによって金型内への粉砕物の充填を過不足無く行うことができ、また、熱変形温度よりも十分に高い温度で成形することによって気泡の壁を破ることができるので、適度な強度低下を招いて緩衝特性に優れた圧縮特性を有して平滑な外観を備え、十分に固化された緩衝材を得ることができることが確認できた。
【００８５】
実施の形態３．
本実施の形態は、本発明の請求項１〜４、７、１０に係るものであり、以下、図示の実施形態に基づき説明する。図１１は実施の形態３を示す成形した緩衝材を示す断面図、図１２は緩衝材の製造方法を示す製造工程図である。
【００８６】
図１１の断面図に示すように、緩衝材２１の構造は緩衝層４１の表層部分には粒径の小さな微粒粉砕物２９を配した緻密な層を形成して高剛性で高強度の層となっているのに対し、緩衝層４１の内部には実施の形態１及び２と同様の高剛性であっても低強度の粗粒粉砕物３０を備えているので、応力および衝撃力が付加された部分のみに集中することなく、表面層が面方向に分散させる作用を備える。従って、緩衝材２１には応力および衝撃力の付加に対して同じ緩衝能力を発揮したとしても、変形が少ないという特徴がある。
【００８７】
次に、前記構造を成す緩衝材の成型方法を図１２に示す製造工程図を用いて説明する。まず、発泡樹脂を粉砕機により平均粒径が３ｍｍ程度の大きさに粉砕し（Ｓ−１１ａ）、得られた粉砕物をふるい選別により１ｍｍ以下の微粒粉砕物２９とそれ以上の粗粒粉砕物３０に選別する（Ｓ−１１ｂ）。次に、１ｍｍ以下の粉砕物の場合には微粒粉砕物２９の１００部に対して５０部の、１ｍｍ以上の粗粒粉砕物３０には１５部の粉末状を成す半硬化状態のエポキシ樹脂を接着剤として、各々、別のドラム式の混合機に投入して、個別に混合する（Ｓ−１２ａ、Ｓ−１２ｂ）。
【００８８】
半硬化状態のエポキシ樹脂は発泡ウレタンの粉砕物３とは別に、粉末状を成す接着剤であるエポキシ樹脂を調整しておき、これと発泡ウレタンの粉砕物３とを混合したときに接着剤であるエポキシ樹脂および発泡ウレタンの粉砕物３が擦れて発生する静電気によって、発泡ウレタンの粉砕物の粒子表面に均一に付着する状態が得られる。このとき、静電気によって粉砕物の表面に吸着に付さない余剰の接着剤は、粗粒粉砕物３０と混合した（Ｓ−１２ｂ）ものは排除するが、微粒粉砕物２９と混合した（Ｓ−１２ａ）ものは、外殻表面に当接する断熱層の空隙を少なくして剛性に優れた層の形成に寄与するので、そのまま混合する。
【００８９】
また、ここで接着剤として用いたエポキシ樹脂は、後段の熱成形において賦形させる際の塑性変形に支障を来すことなく円滑に行って意匠面に変形を来す要因を含まない低い融点で、さらに短時間の加熱で硬化が進行する高活性なものであり、実施の形態１で用いた表１の組成を有する接着剤を用いた。
【００９０】
さらに、実施の形態１と同様、室温状態にて粉末状態のホットメルト型の接着剤を用いてもよく、発泡ウレタンの熱変形温度以上の高温で接着機能を発現して緩衝材の成形に寄与しうるものであるパラフィン系、アミド系などのホットメルト型接着剤を用いることが有効である。
【００９１】
しかし、発泡ポリスチレンなどの熱可塑性樹脂を備えた発泡樹脂の粉砕物３をこれらホットメルト型の接着剤を用いて接着するには、粉砕物が溶融などによって永久的に変形すること無しに十分な接着性を得る上で、発泡樹脂の熱変形温度よりも相当に低い融点のものしか使用できないという制約を生む。そのため、次工程である発泡樹脂の粉砕物２９、３０との混合時に発泡樹脂の表面に粉砕物同志の摩擦によって発生する静電気を利用して粉末状態で粉砕物表面に付着させる上で、低温状態を維持して行う必要があるなどの課題を残す。したがって、ＥＶＡ樹脂などの低融点の接着剤を用いても良いが、取り扱いが困難なので、先に述べた半硬化状態のエポキシ樹脂を用いることが好ましい。
【００９２】
得られた混合物４１は、不織布２２を緩衝材である緩衝材の受圧面側に相当する下金型の形状に沿って予め載置した（Ｓ−１３）下金型内に、１ｍｍ以下の粒径の微粒粉砕物２９と接着剤の混合物の所定量を均一に密な状態になるように投入した（Ｓ−１４ａ）後、１ｍｍ以上の粒径の粗粒粉砕物３０を含む混合物を均一で密な状態に投入した（Ｓ−１４ｂ）。この上に、不織布２２を沿わせた（Ｓ−１３）反受圧面側に相当する上金型を、混合物に０．２ｋｇ／ｃｍ²の圧縮力が付加できるように調整した状態で載せたときに金型の合わせ面が約１０ｍｍの隙間を形成するように１ｍｍ以上の粒径の粉砕物を含む混合物を追加投入して調整した（Ｓ−１５）。前記状態を確保した後、上金型を完全に降下させて前記混合物に当接させた後に更なる荷重をかけて完全密閉し、５０℃／分以上の速度で１３０℃まで昇温して１０分間の保持を行った後、すぐに金型を徐冷させながら接着剤の硬化を促して固化させた（Ｓ−１６）。この徐冷は、発泡ウレタンの熱変形温度である８０℃までを２０分で到達、その後、室温まで冷却水を用いて３０〜４０℃まで冷却した後に成型品を取り出した（Ｓ−１７）。
【００９３】
高温（１３０℃）での接着剤の硬化時に、発泡樹脂の粉砕物の表面付近にあって破断されたセルを構成する支持のない柱状部分は変形を来しやすいので、表面板近傍に散布した微粉の粉砕物が潰れて密度の高い状態になる。また、接着剤は１３０℃では十分な溶融状態に至っているので粉砕物表面に濡れ易く、特に受圧面を形成する下金型では、より大きな接着面積の確保と過剰の接着剤の固化によって剛性の高い発泡樹脂の層を形成する。併せて、発泡樹脂の粉砕物は高温状態で保持されて強度が低下した状態にあるので、この加圧によってセルの隔壁が破壊された状態のセル構造を有して連通化する。
【００９４】
このような態様の成形方法を用いた場合には、緩衝材２１における受圧面を形成する金型を下位置にすることによって、過剰の接着剤が安定して受圧面に保持できるという特長を備える。反対に、本実施の形態とは逆に上金型に受圧面を有するように変更した場合、上金型の降下を速度を速く押し下げることによって、圧力が下部まで伝わらず圧力が上部表面に集中し、微粒粉砕物のある領域では、微粒粉砕物は正常なセルが少なく、最も圧縮によって変形しやすい（潰れやすい）ので密度が上昇し、より一層の高密度状態で強固に固化して圧縮変形を来し難い層を形成するので、機器を載置した部分に振動などでかかる応力を分散させて集中する負荷を軽減するので、変形しにくくすることができる。
【００９５】
得られた緩衝材２１の受圧面側には、微粒粉砕物２９と通常よりも多くの接着剤を備えて固化せしめたので、粉砕した粒子間に空隙が少ない緻密な層を有している。この緩衝材２１の表面層部分と中心層部分を採取し、その圧縮特性を測定したところ、表５に示すように、緩衝材の受圧面側にある表面層は中心部に比較して約２倍の強度および剛性を得ていることが分かった。
【００９６】
【表５】

【００９７】
ここで、表面層を成す微粒粉砕物２９と接着剤の混合物において、本実施の形態では半硬化状態の粉末状エポキシ樹脂を接着剤に用いたが、これに替えて液状の接着剤を用いても良い。つまり、微粒粉砕物２９と液状の接着剤を混合することによって、ペースト状の混合物が得られるので、これを不織布２２を下金型に沿って載置した（Ｓ−１３）金型内に均一に塗布して配する（Ｓ−１４ａ）ことも有効で、同様の態様を得る上で有効な方法となる。
【００９８】
以上のように、微粒粉砕物２９を金型の受圧面側に配して異なる粉砕物である粗粒粉砕物３０を積層するようにして成形すると共に、微粒粉砕物２９を通常より多くの接着剤で固化したので、高い剛性と強度の表層部分を配した成型品の緩衝材を容易に得ることができる。
【００９９】
実施の形態４．
本実施の形態は、本発明の請求項１２、１３に係るものであり、以下、図示の実施形態に基づき説明する。図１３は使用済みの成形した緩衝材を再生する方法を示す工程図であり、図１４は金型への使用済み緩衝材の配設状態を示す概念図である。
【０１００】
図１４に示す緩衝材２１は受圧面３１に繰返し応力や衝撃力が付加されて大きく変形している反面、梱包用の台板に固定するなどの反受圧面３２の損傷は殆どない。従って、使用前に用いた金型３３内に使用済みの成形した緩衝材３４を投入すると、受圧面３１側に空隙３５が形成される。緩衝材２１の受圧面３１に相当する部分を下にした状態で配した金型３３内に、粉砕物と接着剤の混合物３６を投入した後に、使用済みの緩衝材３４を載置することによって空隙３５部分を混合物３６で充填して固化させ、本来の形状を確保するようにしたものである。
【０１０１】
次に、図１３の緩衝材の再生方法を示す工程図を用い、その再生方法を説明する。まず、使用済みの緩衝材３４の受圧面３１部分を下に配した金型３３内に、例えば冷蔵庫の断熱材である発泡ウレタンを１〜５ｍｍの大きさに粉砕した粉砕物と粉末状を成す半硬化状態のエポキシ樹脂である接着剤とを、１００：２０の重量比で予め混合（Ｓ−２１）して得られた混合物３６を投入する（Ｓ−２２）。
【０１０２】
この混合物３６は、本来の緩衝材３４の容積に対する重量（見掛けの密度）と概略の空隙容量から求めた重量を投入するもので、投入した前記混合物３６上に、図１４の概念図のように、使用済みの緩衝材３４を載置（Ｓ−２３）し、さらに反受圧面３２側の金型（図示せず）を合体する（Ｓ−２４）。次に、内部にある粉砕物と接着剤の混合物３６が損傷によって生じた不均一な空隙内に均一な分散状態を呈するように、金型３３を反転させて（Ｓ−２５）保持する。
【０１０３】
この金型３３を５０℃／分以上の速度で１４０℃まで昇温させると共に金型３３に更なる荷重をかけて完全密閉して１０分間の保持によって固化させた（Ｓ−２６）後、室温まで冷却させて取り出す（Ｓ−２７）ことによって、受圧面３１の損傷部分に発泡ウレタンと接着剤の混合物３６を密な状態で固化したものを備えて修復された緩衝材２１を得た。
【０１０４】
また、上記の方法によれば、同一の緩衝材を用いなくとも、金型３３内に投入した使用済みの緩衝材３４との間で形成される空隙３５の大きさに応じて、粉砕物と接着剤の混合物３６によって欠如している形状部分を埋めて成形することができるので、粉砕物として本発明の使用済みの緩衝材を活用しても良い。
また、本実施の形態では、形状が欠如している部分を修復する際に、金型３３の内面に不織布を載置せずに行ったが、前述の実施の形態と同様に不織布を金型３３に沿って載置した後、工程Ｓ−２２以降を実施すると共に、工程Ｓ−２７の取出し後に不要部分の不織布を削除することにより修復してもよい。
【０１０５】
以上のように、本発明に係る上記方法によれば、緩衝材を再度の粉砕に供すること無しに使用済みの緩衝材を本来の形状に、容易に再生、修復することができる。
【０１０６】
なお、以上のように、本発明の各々の実施の形態では成形した緩衝材およびその成型方法について説明したが、本発明はこれに限定されるものではなく、例えば、冷蔵庫、保冷車や建築物などの保温、保冷に用いる断熱材、軽量で高剛性の構造体において板材の中間に挟んで用いる構造材、など、従来の発泡樹脂の用途への代替え使用も可能であり、その要旨を脱し得ない範囲で種々変形して実施することができる。
【０１０７】
【発明の効果】
本発明の第１の発明に係る緩衝材は、繊維を非直線で無秩序な配向状態で保持して成る不織布と、発泡樹脂を粉砕した粉砕物と接着剤を混合した混合物とを前記不織布で被って成形した緩衝層と、を備え、前記緩衝層は、少なくとも圧力がかかる受圧面近傍では、前記発泡樹脂のセルが成形により変形して潰れ、剛直な層を成すので、表面の脆さを補って、成型品の一部分が欠落するのを防止できる上に、廃棄処理後の燃焼に対して有害なガスを発生することなく容易に廃棄できる。また、機器などを載置し、さらにこれが衝撃力を受けた場合に、この層がその下部にある粉砕物に架かる応力を分散させる作用を醸し出すので、局部的に大きな応力の付加を受けることなく、従って緩衝材である成型品が変形し難くなるという特徴を得ることができる。
【０１０９】
本発明の第２の発明に係る緩衝材は、発泡樹脂の粉砕物の粒度は各々異なり、前記発泡樹脂粉砕物のうち粒径の小さなものを緩衝層の受圧面側に配したので、機器などを載置し、さらにこれが衝撃力を受けた場合に、この剛直な層がその下部にある粉砕物に架かる応力を分散させる作用を醸し出すので、局部的に大きな応力の付加を受けることなく、従って緩衝材である成型品が変形し難くなるという特徴を得ることができる。
【０１１０】
本発明の第３の発明に係る緩衝材は、緩衝層が発泡樹脂の粉砕物の間の空隙に、接着に寄与しない過剰の接着剤を含んで成るので、成型時に下方位置にある金型表面近傍の空隙を少なくして剛性の高い層を形成するのに活用できる。
【０１１１】
本発明の第４の発明に係る緩衝材は、緩衝層が連通する気泡を備えるので、付加された応力による歪みを吸収して反発する挙動を抑制するので、緩衝特性を向上させることができる。
【０１１２】
本発明の第５の発明に係る緩衝材は、発泡樹脂の粉砕物が、連通化した気泡を備えたので、セル内にあるガスが高温時の膨張するときに系外に排出するなどして外気と同じ圧力に維持することによって断熱壁体の寸法膨張を抑制できるとともに、搬送時の衝撃による圧縮変形時にセル内にある空気などのガスを排出して過度な反発力の発生も抑制することができる。
【０１１３】
本発明の第６の発明に係る緩衝材の製造方法は、不織布を下金型に載置する工程と、発泡樹脂を含む粉砕物と粉末状の接着剤の混合物を前記不織布を載置した前記下金型内に投入する工程と、不織布を前記混合物の上に載置し、この上に上金型を載置する工程と、前記混合物のうち圧力がかかる受圧面側を前記発泡樹脂の熱変形温度以上に加熱し、反受圧面側を前記発泡樹脂の熱変形温度未満で前記接着剤の融点以上に加熱するとともに、前記接着剤を溶融させた後に成形し、前記受圧面近傍の前記発泡樹脂のセルが成形により変形して潰れ、剛直な緩衝層を成すようにする工程と、を備えたので、受圧面が無発泡状態に近い態様で剛性の高い状態であっても、他の部分が緩衝特性に優れる発泡樹脂を備えて、外観の平滑性に優れた成型品が得られる。
【０１１４】
本発明の第７の発明に係る緩衝材の製造方法は、不織布を下金型に載置する工程と、発泡樹脂を含む粉砕物と接着剤との混合物を、受圧面を形成する面が下位置とする前記不織布を載置した前記下金型内に投入する工程と、前記下金型に投入された前記混合物に上下動を付与する工程と、前記工程の後または前に不織布を前記混合物の上に載置し、この上に上金型を載置する工程と、前記上下動を付与された混合物のうち、少なくとも圧力がかかる前記受圧面近傍を前記発泡樹脂の熱変形温度以上に加熱し、前記発泡樹脂が溶融または分解に至らない温度で前記接着剤を溶融させた後に成形し、前記発泡樹脂のセルが成形により変形して潰れ、剛直な緩衝層を成すようにする工程と、を備えたので、圧縮によって潰され易い粒径の小さい粉砕物と過剰の接着剤が受圧面に集まって剛性の高い受圧面と気泡の連通化を達成して緩衝特性に優れる発泡樹脂を備えた平滑な外観の成型品が得られる。
【０１１５】
本発明の第８の発明に係る緩衝材の製造方法は、上下動は、振動付与によって行なうことによって、落下時に空隙を備える上下動が衝撃的な微振動によって達成されるので、粉砕物を収縮させて外観を損ないにくく、外観の平滑性に優れた成型品が得られる。
【０１１６】
本発明の第９の発明に係る緩衝材の製造方法は、発泡樹脂の粉砕物をあらかじめ定められた粒径毎に分級する工程と、分級した各々の前記粉砕物と接着剤を混合した混合物を得る工程と、不織布を下金型に載置する工程と、受圧面を形成する位置に小さい粒度の前記混合物が配設されるように、前記不織布を載置した前記下金型に順次投入する工程と、不織布を前記混合物の上に載置し、この上に上金型を載置する工程と、少なくとも圧力がかかる前記受圧面近傍を前記発泡樹脂の粉砕物の熱変形温度以上で、前記発泡樹脂の粉砕物が溶融または分解に至らない温度に加熱して前記混合物を成形し、前記発泡樹脂のセルが成形により変形して潰れ、剛直な緩衝層を成すようにする工程と、を備えたので、付加された応力を面方向に分散して、変形を来しにくい成型品を得ることができる。
【０１１７】
本発明の第１０の発明に係る緩衝材の製造方法は、発泡樹脂粉砕物が、発泡樹脂の気泡の直径の３倍以上で、かつ１０ｍｍ以下の直径のものを用いたので、効率よく気泡を連通化させることができるので、優れた緩衝特性と外観を有する成型品を得ることができる。
【図面の簡単な説明】
【図１】 本発明の実施の形態１を示す緩衝材の斜視図である。
【図２】 図１の断面図である。
【図３】 本発明の実施の形態１を示す緩衝材を製品の上部に用いた例を示す概念図である。
【図４】 本発明の実施の形態１を示す緩衝材の製造方法を示す製造工程図である。
【図５】 本発明の実施の形態１を示す緩衝材の成形方法を示す説明図である。
【図６】 本発明の実施の形態２を示す緩衝材の製造方法を示す製造工程図である。
【図７】 粉砕物とする断熱材を備えた冷蔵庫の構造を示す断面図である。
【図８】 断熱材の気泡構造を示す概念図である。
【図９】 熱力学的分析装置（ＴＭＡ）を用いて測定した温度と寸法変化の関係図である。
【図１０】 本発明の実施の形態２を示す緩衝材の製造方法を示す製造工程図である。
【図１１】 本発明の実施の形態３を示す緩衝材の内部構造を示す断面図である。
【図１２】 本発明の実施の形態３を示す緩衝材の製造方法を示す製造工程図である。
【図１３】 本発明の実施の形態４を示す緩衝材の製造方法を示す製造工程図である。
【図１４】 本発明の実施の形態４の製造方法で金型への使用済み緩衝材の配設状態を示す概念図である。
【図１５】 従来の粉砕物を一体化させて得た緩衝材の外観図である。
【符号の説明】
３ 発泡樹脂の粉砕物、４ 接着剤、２１ 緩衝材（成型品）、２２ 不織布、２７ セル膜、２８ 支柱部分、２９ 微粒粉砕物、３０ 粗粒粉砕物、３１ 受圧面、３２ 反受圧面、３４ 使用済みの緩衝材、３６、４０ 発泡樹脂の粉砕物と接着剤の混合物、４１ 緩衝層。[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a cushioning material used to relieve shock stress such as vibration applied during product transportation of various precision instruments to prevent product damage, and more specifically, heat insulating material recovered from a discarded refrigerator, etc. , Molded product that is a buffer material using various hard resin foams and its manufacturing methodTo the lawIt is related.
[0002]
[Prior art]
Reduced disposal of used foamed resin molded products that are difficult to reuse, such as cushioning materials, heat insulating materials and structural materials for the purpose of environmental protection, as well as spills and harmful emissions of harmful substances that occur when they are discarded or burned In order to eliminate the generation of gas, applications and techniques for effectively utilizing or reusing these foamed resins are required.
[0003]
Above all, polystyrene foam and urethane foam are lightweight and have excellent cushioning and heat insulation properties, can be selected from any density and wide rigidity according to the purpose, and have advantages such as low cost and excellent moldability. It is often used as packaging and cushioning materials for transporting a wide variety of products, as heat insulation materials for refrigerators and houses, and as structural materials.
[0004]
Among these foamed resins, regarding the effective use or reuse of a cushioning material called a cushion made of a soft foamed resin, conventionally, the cushioning material is mixed with an adhesive and heated under pressure by mixing the pulverized product with an adhesive. Reproduced and used it. For example, in Japanese Patent Application Laid-Open No. 5-209082, after filling a container (or in a mold) with a hot-melt adhesive, a combustible gas is exploded and burned in the container, and its heat and pressure are increased. Has proposed a method for integrating the crushed pieces. As a result, even foams such as polyolefin that are difficult to bond can be reliably bonded in a short time. Japanese Patent Laid-Open No. 5-209083 proposes to use expanded polystyrene as an adhesive instead of a hot-melt type adhesive in the same manner, and this method also has a similar effect through a similar action. The effect is gained.
[0005]
On the other hand, regarding a hard foamed resin centered on a heat insulating material and a structural material, in Japanese Patent Laid-Open No. 8-258160, a hard foamed urethane obtained from a waste material such as a building material or a refrigerator has an average particle diameter of at least 2 mm. A method is proposed in which an arbitrary cushioning material is obtained from a slab obtained by mixing and curing an adhesive such as isocyanate to a pulverized product, and reusing it as an impact silencer or a heat insulating material. Further, in Japanese Patent Laid-Open No. 10-78192, a slab obtained by the above method is applied to a core member that is in the outer shell of a vacuum heat insulating panel and has a function of preventing deformation due to atmospheric pressure and maintaining its shape. It is stated that a cut-out product is used.
[0006]
Furthermore, in Japanese Patent Laid-Open No. 9-216293, as shown in FIG. 15, while uniformly spraying a moisture-curing adhesive on the mixture 5 of the urethane foam pulverized product 2 and the foamed styrene pulverized product in the form of a spray. A method for obtaining a cushioning material 1 by applying and integrating the pulverized material is proposed. According to this method, first, as shown in FIG. 15A, used foamed urethane 2 crushed to a size of 3 to 30 mm of expanded polystyrene 3 is a moisture curable adhesive 4. A polyurethane prepolymer having free isocyanate groups is mixed while sprayed. Next, in the step shown in FIG. 15 (b), after the mixture 5 is transferred to the mold 6, in the step shown in FIG. The adhesive is cured by the water vapor 11 filled in the mold 6 through the pipe 9 and the hole 10 installed in 8. As shown in FIG. 15 (d), the cushioning material 1 obtained by aging the material cured to the extent that the shape can be maintained is formed by the adhesive 4 in which the urethane foam 2 and the polystyrene foam 3 are adhered to the surface. It is a buffer material that is held together.
[0007]
[Problems to be solved by the invention]
However, since the above cushioning material forms a slab and then obtains an arbitrary shape by cutting, labor is required, and it is difficult to reproduce a subtle shape as a part for packaging and receiving a product. In addition, when the corners and surface of the molded cushioning material using a hard foam resin are rubbed, the foamed resin pulverized product comes off and powder comes out, requiring great care in handling. Under the influence of the powder, the types of products to be packed and the method of internal packaging are also limited.
[0008]
Even if a cushioning material having an arbitrary shape is obtained by filling a mold or the like, when a variety of equipment is placed and used for transportation, the foamed resin on the surface portion is not necessarily strong. Since it is not selectable, it may cause local deformation such as depression of only the pressure-receiving part, and if it is used for a long period of time, the purpose of buffering cannot be achieved, and the packed equipment may be damaged. there were.
[0009]
Also, as a hot melt type adhesive used to obtain a cushioning material formed by solidifying a foamed resin pulverized product, in order to avoid molding conditions at high temperatures that cause thermal deformation of the foamed resin The one having a low melting point is used. However, when using a molded product that is a buffer material regenerated using this adhesive, the melting point of the hot-melt adhesive is used to avoid the situation where the weight of the packaged product is damaged and the shape is damaged. Therefore, there is a disadvantage that the usable temperature of the original cushioning material before the regeneration is lowered.
[0010]
On the other hand, in one-component adhesives such as isocyanate, it takes a long time to cure and solidify the adhesive in the mold after mixing with the pulverized foamed resin, and occurs when the adhesive is cured. It is also necessary to discharge the by-product carbon dioxide gas so that it does not remain in the mold or in the buffer material, which requires a long cycle time for molding, and a complicated design that takes into account the shape of the mold. In addition, since a simple structure is required, there is a disadvantage that the production efficiency is inferior.
[0011]
In addition, the cushioning material with a foam resin that has hard and continuous bubbles is different from the soft cushioning material without the rebound when the deformation due to the absorption of the impact is recovered. Since it absorbs without generating repulsive force, it has the feature of excellent buffering characteristics. On the other hand, since it has a problem that it cannot be used again due to the deformation, some sort of disposal processing is necessary.
[0012]
  The present invention has been made in order to solve the above-mentioned problems, and has a characteristic suitable for the brittleness of the surface layer and the strength of the pressure-receiving surface portion by effectively using the pulverized material obtained from the discarded foamed resin or the like. Obtaining molded cushioning materialAndObjective.
[0013]
[Means for Solving the Problems]
  The cushioning material according to the first aspect of the present invention covers a nonwoven fabric in which fibers are held in a non-linear and disordered orientation state, and a mixture obtained by mixing a pulverized product of foamed resin and an adhesive with the nonwoven fabric. A buffer layer molded byIn the buffer layer, at least in the vicinity of the pressure-receiving surface where pressure is applied, the foamed resin cell is deformed and crushed by molding to form a rigid layer.Is.
[0015]
  First of the present invention2In the cushioning material according to the invention, the pulverized foamed resin has different particle sizes, and the pulverized foamed resin has a smaller particle diameter disposed on the pressure-receiving surface side of the buffer layer.
[0016]
  First of the present invention3In the cushioning material according to the present invention, the cushioning layer includes an excess adhesive that does not contribute to adhesion in the gaps between the pulverized foamed resins.
[0017]
  First of the present invention4In the cushioning material according to the invention, the cushioning layer includes bubbles that communicate with each other.
[0018]
  First of the present invention5The shock-absorbing material according to the invention includes bubbles in which a foamed resin pulverized product is communicated.
[0019]
  According to a sixth aspect of the present invention, there is provided a cushioning material manufacturing method comprising: placing a nonwoven fabric on a lower mold; and placing the nonwoven fabric on a mixture of a pulverized product containing a foamed resin and a powdery adhesive. The step of putting in the lower mold, the step of placing the non-woven fabric on the mixture, the step of placing the upper die on the mixture, and the pressure receiving surface side to which pressure is applied in the mixture Heating above the deformation temperature, heating the pressure-receiving surface side below the thermal deformation temperature of the foamed resin above the melting point of the adhesive, and molding the adhesive after meltingThe foamed resin cell in the vicinity of the pressure-receiving surface is deformed and crushed by molding to form a rigid buffer layer.And a step of performing.
[0020]
  According to a seventh aspect of the present invention, there is provided a cushioning material manufacturing method comprising: placing a non-woven fabric on a lower mold; and mixing a mixture of a pulverized product containing a foamed resin and an adhesive with a surface forming a pressure-receiving surface below. A step of throwing the nonwoven fabric placed at a position into the lower mold, a step of vertically moving the mixture put into the lower mold, and a nonwoven fabric after or before the step. A step of placing the upper mold on the substrate, and a mixture provided with the vertical movementAmong these, at least the pressure-receiving surface vicinity where pressure is applied is equal to or higher than the thermal deformation temperature of the foamed resin.Molding after heating and melting the adhesive at a temperature at which the foamed resin does not melt or decomposeAnd the foamed resin cell is deformed and crushed by molding to form a rigid buffer layer.And a step of performing.
[0021]
  First of the present invention8In the cushioning material manufacturing method according to the invention, the vertical movement is performed by applying vibration.
[0022]
  According to a ninth aspect of the present invention, there is provided a cushioning material manufacturing method comprising: a step of classifying a pulverized product of a foamed resin for each predetermined particle size; and a mixture obtained by mixing each of the classified pulverized product and an adhesive. A step of obtaining, a step of placing the nonwoven fabric on the lower mold, and a step of sequentially charging the lower mold on which the nonwoven fabric is placed so that the mixture having a small particle size is disposed at a position where the pressure receiving surface is formed. Placing the nonwoven fabric on the mixture and placing an upper mold thereon,At least near the pressure-receiving surface where pressure is applied, at or above the heat deformation temperature of the pulverized foam resin,Molding the mixture by heating to a temperature at which the pulverized foamed resin does not melt or decomposeAnd the foamed resin cell is deformed and crushed by molding to form a rigid buffer layer.And a step of performing.
[0023]
  First of the present invention10In the method for producing a cushioning material according to the invention, the foamed resin pulverized product has a diameter of not less than 3 times the diameter of the foamed resin bubbles and not more than 10 mm.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
This embodiment relates to claims 1, 2, and 7 of the present invention, and will be described below based on the illustrated embodiment. 1 is a perspective view showing a molded cushioning material according to Embodiment 1, FIG. 2 is a sectional view showing the internal structure of the AA section in FIG. 1, and FIG. 3 is a concept showing an example of use of the cushioning material in FIG. FIG. 4, FIG. 4 is a manufacturing process diagram illustrating a manufacturing method of the cushioning material, and FIG. 5 is an explanatory diagram of the molding method.
[0027]
First, the cushioning material of the present invention will be described. The embodiment shown in FIGS. 1 and 2 is used in the upper or lower part of the refrigerator 20 that is packed in the state as shown in the conceptual diagram of FIG. Is a buffer material 21 for absorbing the water. 2A is a cross-sectional view of the molded cushioning material 21, and FIG. 2B is a partially enlarged view of FIG. 2A. The cushioning material 21 is composed of a cushioning layer 41 in which a foamed polystyrene pulverized product 3, which is a foamed resin used as a heat insulating material or a cushioning material, is solidified via an adhesive 4, and a cushioning layer. It consists of a non-combustible non-woven fabric 22 rich in flexibility, which is obtained by making a pulp fiber material, which is a porous sheet 41 as an exterior, without orientation. In FIG. 2, P denotes a pressure receiving surface that absorbs an impact when used in the upper or lower part of the refrigerator 20.
[0028]
The amount of the adhesive 4 used is an arbitrary amount capable of solidifying the pulverized product 3 between 5 to 50% by weight. Therefore, the density of the buffer material 21 at this time is equal to the amount of the adhesive 4 used and the expanded polystyrene is pulverized. Although it is greatly influenced by the density of the product 3 and the size and volume (volume) of the voids formed between the pulverized products, it is preferable to secure 80 to 200% with respect to the density of the pulverized polystyrene foam. 100 to 150% is more preferable.
[0029]
On the other hand, the adhesive 4 used here maintains a powder state in which a state in which it is uniformly adhered to the surface is obtained by static electricity generated by the friction between the pulverized polystyrene foams 3 during mixing, causing deformation of the expanded polystyrene. Those having a low melting point are preferred, and if it is a thermosetting resin, it is preferably a highly active one that cures at room temperature. As an example, Table 1 shows the composition of the adhesive used in this embodiment.
[0030]
[Table 1]

[0031]
A method for producing the adhesive 4 using the above raw materials will be described below. First, after uniformly mixing these raw materials shown in Table 1, for example, thinly sprayed on a sheet having heat resistance and flexibility such as polyethylene terephthalate and aluminum foil, and this was kept in a dryer maintained at 90 ° C. A minute drying process is performed to advance the removal of acetone and the preliminary reaction. Since the obtained adhesive is very brittle and can be easily pulverized, it is not always necessary to perform pulverization and may be used as it is.
[0032]
Next, a method of manufacturing the cushioning material will be described based on the process diagram of FIG. 4 and the explanatory view of the molding method of FIG. FIG. 5A is an explanatory view of a molding method, in which 22 is a nonwoven fabric, 40 is a mixture of the foamed resin pulverized product 3 and the adhesive 4, 42 is a lower mold, and 43 is an upper mold.
FIG. 5B shows the state after molding, 41 is a buffer layer, 22a is a non-woven fabric that is not required, and P is a pressure-receiving surface.
[0033]
First, the recovered expanded polystyrene is pulverized to a size having an average particle diameter of 5 mm or less, preferably about 2 mm, using a pulverizer that has a rotary blade and is finely divided by cutting (S). -1). Next, a predetermined amount of the powder of the pulverized product 3 and the adhesive 4 is put into a drum type mixer and mixed (S-2). The obtained mixture 40 was thrown into the lower mold 42 in which the nonwoven fabric 22 was placed along the shape of the lower mold 42 (S-3) while adjusting a predetermined amount so as to be in a dense and uniform state. (S-4). The lower mold 42 used here has a shape in which a pressure receiving surface P is formed.
[0034]
Next, the nonwoven fabric 22 is placed on the mixture 40, and the upper mold 43 is placed thereon, and the mixture 40 is loaded with 1 kg / cm 2.²Below, preferably 0.2 kg / cm²(S-5). At this time, the temperature of the upper mold 43 is adjusted to 80 ° C. which is higher than 70 ° C. which is the melting point of the adhesive without reaching the thermal deformation temperature of the expanded polystyrene, and the temperature of the lower mold 42 is expanded polystyrene. The temperature was adjusted to 140 ° C., which is equal to or higher than the heat distortion temperature. After the upper mold 43 was placed, the adhesive was cured by holding and molding in a heated state for 10 minutes (S-6). Then, it was cooled to room temperature and taken out (S-7). In this state, as shown in FIG. 5B, unnecessary nonwoven fabric 22a remains, and this was cut and finished to obtain cushioning material 21.
[0035]
Since the molded cushioning material 21 obtained as described above uses an epoxy resin containing a high concentration amine-based catalyst as an adhesive, the reaction gradually proceeds even in a room temperature atmosphere. Complete curing is achieved, and a buffer material having a high heat distortion temperature is obtained. For this reason, in subsequent use, since it has a heat deformation temperature of 110 ° C. that exceeds the use temperature of expanded polystyrene, which is the original buffer material, it is necessary to lower the use temperature of the buffer material 21 obtained in the present embodiment. Absent.
[0036]
Moreover, since the foamed polystyrene pulverized products 3 are held together using a semi-cured epoxy resin as an adhesive, the surface is smooth and voids such as voids are used even when using a mold that does not require special measures. Thus, it was possible to obtain the cushioning material 21 having a structure that does not easily contain. In addition, when it receives a strong impact force as a cushioning material, it absorbs by breaking and deforming near the interface between the crushed material and the highly rigid epoxy resin that joins them, so it is flexible and highly repulsive Even if expanded polystyrene is used, it does not receive the impact repulsive force and can exhibit excellent buffer characteristics.
[0037]
In addition, the nonwoven fabric 22 used for the exterior does not cause the adhesive 4 to be completely cured and does not produce a strong adhesive force, thereby avoiding the problem that the foamed polystyrene pulverized product 3 is lost during a period of brittle nature. be able to. On the other hand, the exterior material used here is a flexible porous sheet having a nonwoven fabric shape in which fibers are held in a non-linear and disordered orientation state. Even in a state where it does not contact the surface, since the fiber is easily displaced in multiple directions and has a behavior that extends linearly, there is a tolerance in the distance that exhibits a deformation of spread with respect to the addition of stress. Therefore, the sheet state can be maintained and integrated with the surface of the buffer layer 41 without being easily broken. Furthermore, the nonwoven fabric 22 of the exterior material used here hardly generates harmful gas even if it is burned, so that the treatment is simple.
[0038]
Further, since the temperature of the lower mold 42 that forms the portion corresponding to the pressure receiving surface P of the buffer material 21 is set higher than the thermal deformation temperature of the expanded polystyrene constituting the pulverized product 3, Since the resin portion is softened and the cells are deformed and crushed by compression during molding, the resin layer becomes dense and forms a rigid layer. When a device or the like is placed here, and when this is subjected to an impact force, this rigid layer produces an action to disperse the stress on the pulverized material underneath, so that there is no significant local addition. Therefore, it is possible to make the molded cushioning material 21 difficult to deform.
[0039]
In the present embodiment, a semi-cured epoxy resin is used as an adhesive, but instead of this, a melting point suitable for bonding without greatly impairing the bubble shape of the pulverized polystyrene foam (room temperature to 85). C., preferably 60-70.degree. C.), for example, EVA (ethylene-vinyl acetate copolymer) resin may be used.
[0040]
Embodiment 2. FIG.
The present embodiment relates to claims 1 to 9 and 11 of the present invention, and will be described below based on the illustrated embodiment. The configuration of the cushioning material in the present embodiment is the same as that of the first embodiment shown in FIGS. Since the mold used for molding is the same as that of the first embodiment, the manufacturing method of the cushioning material will be described with reference to the manufacturing process diagram of FIG. 6 and the explanatory diagram of the molding method of FIG.
[0041]
The pulverized foamed resin used in the present embodiment is the heat insulation inside the outer shell together with the inner box 23 and the outer box 24 constituting the outer shell after pulverizing the heat insulating box body 26 of the refrigerator having the structure shown in FIG. If the urethane foam, which is the material 25, is put into an air flow (such as a cyclone classifier) that produces a centrifugal separation action, it can be easily separated and recovered as a light substance with a much lower specific gravity than other components. .
[0042]
In the present invention, in order to obtain sufficient buffering characteristics, it is preferable to use a material having independent bubbles partitioned by the cell membrane 27, such as the bubble structure of the pulverized heat insulating material 25 shown in the conceptual diagram of FIG. preferable. In addition, it is necessary to have such a structure and be made of a resin that is difficult to be decomposed or thermally deformed. As such a foamed resin, a foamed urethane, which is a thermosetting resin, is most widely used. Moreover, what was collect | recovered from the lightweight heat insulation structure board for building materials other than the heat insulation wall of a refrigerator may be used.
[0043]
In the manufacturing method, first, the heat insulating material obtained from the heat insulating box described above is used in the same manner as in the first embodiment, using a pulverizer having a rotating blade, and the diameter of the pulverized product is the size of the foam bubbles ( And a size having an average particle diameter of 3 mm or more and a diameter of 10 mm or less, preferably about 2 mm. The bubble diameter is 100 to 300 microns (S-1). Next, a predetermined amount of the powder of the pulverized product 3 and the adhesive 4 is put into a drum type mixer and mixed (S-2). In the obtained mixture 40, the non-woven fabric 22 was previously placed along the shape of the lower mold (S-3), and a predetermined amount was put into a substantially uniform state in the lower mold 42 (S-4).
[0044]
The difference from the first embodiment in the configuration of the adhesive is that the curing temperature is heated at 130 ° C., which is sufficiently higher than the heat deformation temperature of foamed urethane, at 130 ° C. for 10 minutes. With this change in heating conditions, as shown in Table 2, the composition for making the handling of the adhesive easy is to reduce the reaction rate by reducing the amount of imidazole which is the catalyst of the epoxy resin and to make the solvent safe. Changed to highly functional methyl cellosolve.
Furthermore, with the change of the type of the solvent, the heating conditions in the thermostat for progressing the drying treatment and the preliminary reaction were changed to 120 ° C. for 10 minutes.
[0045]
[Table 2]

[0046]
When the urethane foam pulverized product 3 is mixed, the semi-cured epoxy resin as an adhesive is very brittle and easily pulverized to form a fine powder, and the adhesive and the urethane foam pulverized product 3 are charged. Therefore, the powder of the semi-cured epoxy resin, which is the above-mentioned adhesive, is subjected to electrostatic adhesion on the surface of the pulverized product 3. At this time, the amount of the semi-cured epoxy resin as the adhesive can be sufficiently obtained by adding almost the same weight, and moreover, the surplus semi-cured epoxy that does not adsorb on the surface of the pulverized foam resin Can be used to form a highly rigid layer by reducing the gap in the vicinity of the surface of the lower mold 42 located at the lower position at the time of molding.
[0047]
Next, the input amount of the mixture 40 of the foamed resin pulverized product 3 and the adhesive 4 obtained in the above step with respect to the volume (L) in the lower mold 42 is V obtained by the following equation (1). .
[0048]
αV = W1 / D1 + W2 / D2 (1)
W = W1 + W2 (2)
W: input amount of the mixture of the foamed resin pulverized product 4 and the adhesive (g)
α: Overfill rate
V: Volume of the void in the mold (L)
W1: Weight in the mixture of pulverized foamed resin (g)
D1; density of foamed resin (g / L)
W2: Weight in adhesive mixture (g)
D2: density of the adhesive (g / L)
[0049]
According to the above formula, when α is 1, the foamed resin is not compressed and contracted, and the pulverized products 4 are in close contact with each other to form a heat insulating layer. Further, if α is greater than 1, excessive compression deformation is imparted, so that it is possible to ensure a state in which deformation is difficult during actual use.
[0050]
The pulverized material of the heat insulating material used here was individually communicated by a partition wall 27, which is a resin thin film in which adjacent cells constitute a foamed resin, like the bubble structure of the pulverized heat insulating material 25 shown in the conceptual diagram of FIG. It has a structure and its diameter is 100-300 microns. In such a cell structure, most of the strength against the addition of stress such as impact force applied during the mounting and transportation of products such as equipment is columnar formed by tangential parts where three or more cells are adjacent. This is due to the ramen structural element supported by the portion 28. The compressive strength affected by the deformation such as buckling deformation of the columnar portion 28 is 1.5 to 2.0 kg / cm in the case of the heat insulating material of the refrigerator.²It is.
[0051]
However, in the portion where the particles of the pulverized material filled in the nonwoven fabric 22 in the outer shell are in contact, the pressure receiving surface is small and the structural defect accompanying pulverization (the state where the end of the columnar portion 28 of the cell is not supported) Since the surfaces of the pulverized product are in contact with each other, it is in a state where it easily undergoes buckling deformation, and simply spraying the pulverized product causes a significant decrease in strength and develops strength that can be used as a cushioning material. Is difficult. Therefore, in order to obtain the strength according to the weight of the product to be placed, it is important that α in the formula (1) is larger than 1. According to the particle size of the urethane foam pulverized product (the end of the particle size) The ratio of the length of the columnar portion 28 of the cell having no support of the portion), α is preferably set to 1.05 to 2.0, and particularly preferably 1.2 to 1.5.
[0052]
Next, a slight vibration is applied to the lower mold 42 into which the mixture 40 of the foamed resin pulverized product and the adhesive is charged (S-5). This allows the pulverized product to move up and down appropriately so as to fit in a stable position and is packed in a close-packed state, and due to the difference in the speed at which each raw material floats and sinks due to the difference in specific gravity, a foam resin having a small specific gravity, In particular, a pulverized product with a large particle size floats upward most, and a pulverized product 3 with a small particle size provided with an adhesive having the largest specific gravity sinks. Accordingly, in the lower mold 42, the composition of the pulverized product 3 of the foamed resin with a small particle diameter containing a large amount of adhesive is concentrated in the vicinity of the pressure receiving surface by setting the pressure receiving surface of the cushioning material 21 to the lower position. In addition to forming a strong layer, a large amount of pulverized product with a large particle size that does not attach excessive adhesive to the surface can be accumulated in the vicinity of the opposing surface to ensure continuous voids between the particles of the pulverized product 3 of the foamed resin. It becomes like this.
[0053]
  Next, the nonwoven fabric 22 is placed on the mixture 40, and the upper mold 43 is placed thereon, and a compressive stress of 1 kg / cm 2 or less, preferably 0.2 kg / cm 2 is applied to the mixture 40 (S-6). At this time, the temperature of the upper mold 43 is adjusted to 120 ° C. which is higher than 70 ° C. which is the melting point of the adhesive without foaming the foamed polyurethane cell, and the temperature of the lower mold 42 is foamed. The temperature was adjusted to 140 ° C., which causes foam breakage above the heat deformation temperature of urethane. After placing the upper mold 43, the mold is held in a heated state for 10 minutes (S-7) To cure the adhesive. Then, it was cooled to room temperature and taken out (S-8).
[0054]
Here, the nonwoven fabric 22 used for the exterior is a flexible porous sheet that forms a nonwoven fabric shape that protects the surface of the fragile buffer layer 41 and holds the fibers in a non-linear and disordered orientation state. The sheet state can be maintained without being broken and can be integrated with the surface of the buffer layer 41 along the mold shape sufficiently. Furthermore, since this nonwoven fabric 2 hardly generates harmful gas even if it is burned, the incineration treatment after use is simple.
[0055]
  Also, when molding (S-7The temperature of the lower mold 42 is preferably such that the foam breaks at a temperature equal to or higher than the thermal deformation temperature of the urethane foam and does not lead to thermal decomposition. For example, if it is used for the heat insulating material of a refrigerator, it is 85-100 degreeC, and if it is used for the core material for building materials, it is a heat deformation temperature of 90-120 degreeC, Therefore It is decomposition temperature 200- Preference is given to performing at any temperature between 110 ° C. and 160 ° C., much lower than 300 ° C.
[0056]
The heat deformation temperature of urethane foam shown here is the result of measuring the dimensions by pressing a 5 g load on a cylinder having a diameter of 3 mm and a thickness of 5 mm using a thermodynamic analyzer (TMA). As shown in the relationship diagram of temperature and dimensional change shown in Fig. 2, it means an example of a specific temperature (point a) showing a sudden dimensional change, and is a temperature range (point b) higher than that temperature. Above 124 ° C, as the balloons suddenly inflate and then burst, the independent structure of bubbles expands rapidly, leading to cell membrane destruction (bubble breakage). Repeated phenomena have been observed. That is, the shock absorbing material 21 provided with the part which the one part bubble in urethane foam destroyed and was connected was obtained.
[0057]
Since the pulverized urethane foam 3 used here is a cell structure having an independent structure, the gas in the cell expands and deforms at high temperatures during use, or at low temperatures. On the contrary, it may contract. However, since the pulverized product 3 of the foamed resin is held in a high temperature state and has a reduced strength, the internal pressure rises due to the expansion of the gas in the cell due to the heating and the compression deformation due to the pressurization. The partition wall formed in is broken and connected. Dimensional expansion of the heat insulation wall by maintaining the same pressure as the outside air by, for example, exhausting the gas in the cell outside the system when it expands at a high temperature, because a part of the independent cell is connected. In addition, it is possible to suppress the generation of excessive repulsive force by discharging gas such as air in the cell at the time of compressive deformation due to an impact during transportation.
[0058]
In addition, since the adhesive is in a molten state before being pressed, it is easy to get wet on the surface of the pulverized product, and it is easy to ensure a larger adhesion area. When the surface is increased, sufficient wetting can be ensured to bond firmly. In addition, since the gas in the cell is discharged by the compression by pressurization, the buffer obtained is obtained by venting the mold so that it is smoothly discharged out of the system without staying in the system. It is preferable because a defect portion such as a void is not generated inside the material 21 and, therefore, a smooth appearance and a uniform compression characteristic can be secured in the buffer material 21.
[0059]
In addition, hot melt adhesives such as paraffin-based and amide-based ones that have a function as an adhesive at high temperatures accompanied by foam breakage of urethane foam pulverized by such a method can contribute to the molding of cushioning materials. It is also effective to use an agent. In order to bond a foamed resin pulverized product with a thermoplastic resin, these hot melt adhesives are used to bond the pulverized product 3 sufficiently without causing permanent deformation such as melting. In order to obtain the properties, there is a restriction that only those having a melting point considerably lower than the thermal deformation temperature of the foamed resin can be used.
[0060]
On the other hand, when the adhesive is mixed with the pulverized product of the foamed resin, the surface of the foamed resin is adhered to the surface of the pulverized product 3 in a powder state using static electricity generated by friction between the pulverized products 3. The above suggests that it is necessary to devise on the production equipment, such as the need to maintain the low temperature state. However, in the method for enabling bonding at a high temperature using the thermosetting resin foamed resin according to this embodiment, a hot-melt type adhesive that can sufficiently maintain a powder state even at room temperature can be used.
[0061]
If the pulverized product of the foamed resin used here includes a thermoplastic resin such as expanded polystyrene, the pulverized product 3 is permanently deformed such as melting by being sufficiently solidified by melting at a low temperature at which the foamed resin is not deformed. It is important to use the adhesive 4 that can maintain the foamed state so as not to come. In addition to the semi-cured epoxy resin, the buffer material 21 obtained has a low usable temperature. It is also effective to use a resin having a melting point considerably lower than the thermal deformation temperature of foamed resin such as EVA (ethylene-vinyl acetate copolymer) resin. However, since it is difficult to achieve communication of the foamed resin as described above, the shock-absorbing characteristics are inferior to those of the urethane foam described above, but the gold that forms the pressure-receiving surface as described in the first embodiment. If it is used together as a means for forming a rigid surface by raising the temperature of the mold, the effect of dispersing the received load concentrated on the part where the product is installed on the pressure receiving surface is increased, so that deformation can be suppressed.
[0062]
  In the present embodiment, the figure6As shown in the manufacturing process, the vibration application (S-5) was performed before the upper mold 43 was placed (S-6), but the filling rate of the mixture 40 of the foamed resin pulverized product 3 and the adhesive 4 was high. When it is large, the mixture 40 may overflow from the lower mold 42.10As shown in FIG. 4, the vibration is applied after the upper mold 43 is placed, or the lower mold 42 is structured so that the mixture 40 does not overflow.
[0063]
【Example】
The following is a specific example performed to validate the present embodiment. According to claims 7 to 9 and 11 of the present invention, the buffering effect of the buffer material according to claims 1 to 6 was confirmed. Is.
[0064]
Examples 1-5
The manufacturing method of Examples 1-5 was performed based on the shaping | molding method of FIG. 5, and the manufacturing process figure of FIG. First, urethane foam having a bubble size (diameter) of 150 to 200 microns is collected with a heat insulating material of a refrigerator, and pulverized with a pulverizer having a rotary blade. The product was separated and collected into a 10 mm size. And as shown in Table 3, the size of the pulverized material was 0.6 to 3 mm in Example 1, 1 to 5 mm in Examples 2 and 4, and 3 to 10 mm in Examples 3 and 5, respectively. (S-1).
[0065]
[Table 3]

[0066]
Thereafter, Examples 1 to 3 are adhesives that are epoxy resins which are semi-cured thermosetting resins having a melting point of 65 ° C. shown in Table 2, and Examples 4 and 5 have melting points of 60 ° C. and 100 μm or less. 30 parts by weight of 100 parts by weight of the pulverized amide-based hot melt adhesive was added and mixed at room temperature until the adhesive uniformly adhered to the pulverized urethane foam (S -2).
[0067]
Thereafter, the nonwoven fabric 22 is placed on the lower mold 42 along the shape of the lower mold 42 to obtain the cushioning material 21 having an appearance as shown in FIG. 1 and having a width of 580 mm, a height of 70 mm, and a width of 50 mm. (S-3), and the mixture 40 obtained in step S-2 was put into the mold in a uniform and dense state (S-4). The filling amount at this time is such that the apparent density of the mixture 40 of urethane foam, which is the pulverized product 3 of foamed resin, and epoxy resin, which is the adhesive 4, so that a layer having high rigidity on the pressure-receiving surface can be retained. Although the foamed resin pulverized product 3 has many small particle diameters and large particle diameters tend to be small, the input amount for obtaining the buffer material 21 to obtain an average density of about 1.4 times is set. .
[0068]
Next, the nonwoven fabric 22 which is a flexible porous sheet forming a nonwoven fabric is placed, and 0.2 kg / cm²The upper mold 43 adjusted so as to be able to apply the above compressive stress was placed so that the mating surfaces of the upper and lower molds 43 and 42 were 10 to 20% of the product thickness. In this example, the gap was uniform about 25 mm. (S-5). Further, the upper and lower molds 43 and 42 in a sealed state were given slight vibrations (S-6).
[0069]
Here, when the upper mold 43 is placed, the mixture is brought into contact with the mixture 40 and compressed, so that the mixture 40 cannot move up and down due to subsequent fine vibrations to provide a suitable particle size distribution. For this reason, the upper mold 43 was held in a state of being slightly inserted into the lower mold 42 and held so as not to contact the mixture 3. In addition, the vibration application at this time is the optimum condition by adjusting the speed and distance of vibration and time, and as a result, a mixture having a large particle size and holding a minimum adhesive on the upper side of the lower mold 42, A mixture containing a large amount of adhesive with a small particle size in the downward direction with the pressure-receiving surface was formed in a layered manner.
[0070]
In this way, the upper mold 43 is placed on the pulverized mixture 3 of urethane foam and adhesive obtained with the lower mold 42 with an appropriate distribution of particle size and blending ratio, and 130 ° C. at a rate of 50 ° C./min or more. After the temperature was raised to 10 minutes and held for 10 minutes, the upper and lower molds 43 and 42 were brought into close contact with each other and the adhesive was cured by holding for 10 minutes to form (S-7). After molding, the cushioning material 21 molded was obtained by cooling to room temperature and taking it out (S-8).
[0071]
At this time, the upper and lower molds 43 and 42 are in close contact with each other, and as described above, a uniform gap of about 25 mm is formed, but the adhesive is melted between the temperature rise to 130 ° C. and the holding for 10 minutes. The upper mold 43 sinks until the gap between the parts where the upper and lower molds 43, 42 abut is about 15 mm due to creep deformation caused by pressurization due to the addition of the mold weight. In this state, since further pressurization is applied until the upper and lower molds 43 and 42 are completely closed, many of the foamed states of the pulverized material having a small particle size in the vicinity of the pressure receiving surface including many cells including structural defects are included. The layer is crushed and becomes high density, and a layer is formed in which the void formed by contacting the particles of the pulverized material is filled with an excessive adhesive that does not contribute to adhesion.
[0072]
Comparative Example 1
A cushioning material obtained by molding under the same conditions as in the above example using foamed polystyrene as the foamed resin using the mixture of the pulverized product of Example 4 and the adhesive properties was used as Comparative Example 1.
[0073]
Comparative Examples 2 and 3
Similarly, molding was performed at a mold temperature of 80 ° C., which is a molding temperature slightly higher than the melting point of the adhesive, using the mixture having the properties of the pulverized product and the adhesive shown in Example 2 and Example 4. In the buffer material obtained, the former was set as Comparative Example 2, and the latter was set as Comparative Example 3. Regardless of which adhesive was used, the holding time in the mold was 25 minutes, which is considered to have sufficient strength to hold the shape of the buffer material by curing the epoxy resin.
[0074]
Comparative Examples 4 and 5
It is provided with an adhesive which is an epoxy resin which is a semi-cured thermosetting resin having a melting point of 65 ° C. shown in Table 2, and the size of the pulverized product is 0.5 mm or less (Comparative Example 4) or the average diameter A cushioning material was obtained by using the same molding method as that of the above-described example except that the material of 15 mm (Comparative Example 5) was used.
[0075]
The contents of the evaluation are as follows.
(1) Weight of cushioning material
The weight of the obtained cushioning material was determined. In any cushioning material, the difference in the weight of the non-woven fabric forming the epidermis between the samples was very small, so the weight obtained by subtracting the same weight of 4 g was adopted.
[0076]
(2) Appearance design
The result of visual comparison of the smoothness of the appearance is taken as the appearance design, and the surface is smoothed and crushed by voids, etc. with five levels based on the original cushioning material molded with expanded polystyrene before grinding. The uniformity of the solidified state of the object and the reproducibility of the shape (shrinkage occurrence, etc.) were evaluated.
[0077]
(3) Compression characteristics
Preferred properties as a cushioning material are low strength and high rigidity. According to the configuration of both the characteristics, the applied stress forms a permanent strain in the buffer material, so that the repulsive force is not accumulated and the impact force can be absorbed. Specifically, a sample having a pressure-receiving surface of 50 × 50 mm and a thickness of 30 mm was collected from an arbitrary position including the surface layer of the molded cushioning material, and this was compressed at a speed of 10 mm / min. The relationship curve between stress and strain was obtained. The strength is obtained from the applied stress and the pressure receiving area at the time of 10% strain in the region where the curve is stably deformed, and the rigidity is determined from the deformation speed and the pressure receiving area in the region where the stress increases linearly at the initial stage of deformation. Asked.
[0078]
(4) Surface layer rigidity
When the surface of the cushioning material is made of non-woven fabric, a rigid layer consisting of excess adhesive and fine pulverized material is obtained, and the solidified state of the pulverized material in contact with the adhesive is not sufficient In addition, a large deformation, that is, a dent is caused by concentrating on the portion immediately below where the additional stress abuts. On the other hand, if a sufficiently solidified state is obtained, it can be dispersed in the periphery where the stress is applied, and only a small deformation is required, so that the resistance to repeated stress and impact force increases. Accordingly, the rigidity of the surface layer was determined by the amount of penetration of a plug having a 350 g load having a spherical shape with a tip of R5 mm. Specifically, the device was placed at an arbitrary location on the cushioning material, and the amount of penetration was read from the amount of change in the dial gauge after 1 minute. Table 4 shows the results of various measurements described above for the samples of Examples 1 to 5 and Comparative Examples 1 to 5.
[0079]
[Table 4]

[0080]
As described above, according to the method for molding a cushioning material according to the present invention, by performing the curing temperature of the adhesive at 130 ° C., which is sufficiently higher than 96 ° C., which is the thermal deformation temperature of urethane foam as a pulverized product, The foamed gas in the foam expands and the bubble film breaks, so that the gas in the bubbles that repels the compression deformation is discharged outside the system and does not contribute to the strength. It is presumed that a low strength and high rigidity preferable as a cushioning material was obtained. Further, due to the expansion of the foaming gas at this time, the expansion pressure of the gas is added to the pressure generated when pressurizing an excessive filling state in which a gap of 10 mm is formed on the mating surfaces of the molds. As described above, since it is further uniformly added to the pulverized product in a flexible state, it is possible to obtain a cushioning material having an excellent appearance capable of transferring the mold shape and having a highly rigid surface layer. It was.
[0081]
On the other hand, in the case of using the pulverized polystyrene foam of Comparative Example 1, the polystyrene foam has a tendency to shrink with melting in a high temperature atmosphere in the mold, so that the internal pressure of the mold can be sufficiently secured. In addition, the gas staying on the mold surface cannot be discharged out of the system, and an unfavorable appearance state in which many void-shaped recesses are formed and the remaining independent bubbles are retained, resulting in a decrease in strength. I couldn't.
[0082]
Furthermore, similarly to Comparative Examples 2 and 3, since it was a low molding temperature that could not cause bubble breakage, it was not possible to obtain a decrease in strength, and only those having compression characteristics and brittleness that are not desirable as a cushioning material. Couldn't get.
[0083]
Further, in Comparative Example 4, the size of the pulverized product with respect to the bubble diameter was too small, and although an excessive amount was required for charging into the mold, a state sufficient for bonding with the adhesive was not obtained, Therefore, the plug for measuring the rigidity excessively entered the surface layer shown in Table 4, resulting in a very brittle buffer material. On the other hand, when the pulverized material having a very large particle diameter exceeding 10 mm of Comparative Example 5 is used, the pulverized material cannot be charged in a sufficiently dense state, and a smooth state can be obtained on the surface. In addition, it was difficult to break the bubbles to the center of the pulverized foamed urethane particles, and an appropriate reduction in strength could not be caused.
On the other hand, in Example 1, since the size of the bubbles is 150 to 200 microns and the size of the pulverized product is a minimum of 0.6 to 3 mm, it is 3.0 to 20 times the size of the bubbles. In Example 1, the surface layer could maintain high rigidity.
Therefore, it was confirmed that the pulverized foamed resin preferably has a diameter of 3 times or more of the foamed resin foam and a diameter of 10 mm or less.
[0084]
As described above, by using an appropriately sized pulverized urethane foam, the pulverized material can be filled into the mold without excess or deficiency, and molding is performed at a temperature sufficiently higher than the thermal deformation temperature. Since the wall of the bubble can be broken by doing so, it is possible to obtain a sufficiently solidified cushioning material having a smooth appearance with a compression property excellent in cushioning properties, causing a moderate decrease in strength. It could be confirmed.
[0085]
  Embodiment 3 FIG.
  This embodiment relates to claims 1 to 4, 7, and 10 of the present invention, and will be described below based on the illustrated embodiment. FIG. 11 shows an embodiment.3Sectional drawing which shows the shape | molded buffer material to show, FIG. 12: is a manufacturing process figure which shows the manufacturing method of a buffer material.
[0086]
As shown in the cross-sectional view of FIG. 11, the structure of the buffer material 21 is a high-rigidity and high-strength layer formed by forming a dense layer in which fine pulverized material 29 having a small particle size is arranged on the surface layer portion of the buffer layer 41. On the other hand, the buffer layer 41 includes the low-strength coarse pulverized material 30 even if it has the same high rigidity as in the first and second embodiments, so that stress and impact force are applied. The surface layer has a function of dispersing in the plane direction without concentrating only on the portion. Therefore, even if the buffer material 21 exhibits the same buffering capacity against the application of stress and impact force, it has a feature that deformation is small.
[0087]
Next, a method of molding the cushioning material having the above structure will be described with reference to a manufacturing process diagram shown in FIG. First, the foamed resin is pulverized by a pulverizer to an average particle size of about 3 mm (S-11a), and the pulverized product obtained is screened to obtain a finely pulverized product 29 of 1 mm or less and a coarse pulverized product of more than that. 30 (S-11b). Next, in the case of a pulverized product of 1 mm or less, 50 parts of 100 parts of the finely pulverized product 29, and 15 parts of a coarse pulverized product 30 of 1 mm or more are coated with 15 parts of a semi-cured epoxy resin. As an adhesive, each is put into another drum-type mixer and mixed individually (S-12a, S-12b).
[0088]
The epoxy resin in a semi-cured state is prepared separately from the urethane foam pulverized product 3 by adjusting an epoxy resin, which is a powdery adhesive, and mixed with the urethane foam pulverized product 3 with an adhesive. Due to static electricity generated by rubbing a certain epoxy resin and foamed urethane pulverized product 3, a state of uniformly adhering to the particle surface of the foamed urethane pulverized product is obtained. At this time, the surplus adhesive not adhering to the surface of the pulverized product due to static electricity is excluded from the mixture with the coarse pulverized product 30 (S-12b), but is mixed with the fine pulverized product 29 (S-). 12a) contributes to the formation of a layer having excellent rigidity by reducing the voids of the heat insulating layer in contact with the outer shell surface, and is mixed as it is.
[0089]
In addition, the epoxy resin used as an adhesive here has a low melting point that does not include a factor that causes the design surface to deform smoothly without causing any hindrance to plastic deformation when forming in the subsequent thermoforming. Furthermore, an adhesive having a high activity in which curing proceeds with heating for a shorter time and having the composition shown in Table 1 used in the first embodiment was used.
[0090]
Further, as in the first embodiment, a hot-melt adhesive in a powder state at room temperature may be used, and the adhesive function is exhibited at a temperature higher than the thermal deformation temperature of urethane foam, contributing to the molding of the cushioning material. It is effective to use a hot melt type adhesive such as paraffin type or amide type.
[0091]
However, in order to bond the foamed resin pulverized product 3 provided with a thermoplastic resin such as polystyrene foam using these hot-melt adhesives, the pulverized product is sufficient without being permanently deformed by melting or the like. In obtaining adhesiveness, there is a restriction that only those having a melting point considerably lower than the thermal deformation temperature of the foamed resin can be used. Therefore, when adhering to the surface of the pulverized product in the powder state using static electricity generated by friction between the pulverized products on the surface of the foamed resin when mixed with the pulverized product 29, 30 of the foamed resin, which is the next step, Such as the need to maintain Therefore, an adhesive having a low melting point such as EVA resin may be used. However, since the handling is difficult, it is preferable to use the above-described semi-cured epoxy resin.
[0092]
  The obtained mixture 41 placed in advance the nonwoven fabric 22 along the shape of the lower mold corresponding to the pressure-receiving surface side of the buffer material, which is a buffer material (S-13).underA predetermined amount of a mixture of finely pulverized product 29 having a particle size of 1 mm or less and an adhesive is put into a mold so as to be uniformly dense (S-14a), and then coarse particles having a particle size of 1 mm or more are used. The mixture containing the pulverized product 30 was charged into a uniform and dense state (S-14b). On top of this, an upper mold corresponding to the side opposite to the pressure-receiving surface (S-13) along with the nonwoven fabric 22 was added to the mixture at 0.2 kg / cm.²The mixture containing the pulverized material having a particle diameter of 1 mm or more was adjusted so that the mold mating surface formed a gap of about 10 mm when placed in an adjusted state so as to be able to add a compressive force of S-15). After securing the above state, the upper mold is completely lowered and brought into contact with the mixture, and then completely sealed by applying a further load, and the temperature is raised to 130 ° C. at a rate of 50 ° C./min or more. After holding for a minute, the mold was immediately cooled down and the adhesive was hardened and solidified (S-16). In this slow cooling, the temperature reached 80 ° C., which is the thermal deformation temperature of urethane foam, in 20 minutes, and then cooled to 30 to 40 ° C. using cooling water to room temperature, and then the molded product was taken out (S-17).
[0093]
When the adhesive is cured at a high temperature (130 ° C.), the unsupported columnar portions constituting the fractured cells in the vicinity of the surface of the foamed resin pulverized product are likely to be deformed. The finely pulverized product is crushed to a high density state. In addition, since the adhesive is in a sufficiently molten state at 130 ° C., it is easy to get wet on the surface of the pulverized material. Especially in the lower mold forming the pressure receiving surface, the rigidity is secured by securing a larger adhesive area and solidifying the excessive adhesive. Form a high foamed resin layer. At the same time, the pulverized foamed resin is kept in a high temperature state and has a reduced strength. Therefore, this pressurization has a cell structure in which the partition walls of the cells are broken and communicates.
[0094]
When the molding method of such an aspect is used, the mold for forming the pressure receiving surface in the cushioning material 21 is placed at the lower position, so that the excess adhesive can be stably held on the pressure receiving surface. . Conversely, if the upper mold is changed to have a pressure receiving surface, the pressure is not transmitted to the lower part by pushing down the upper mold quickly, but the pressure is concentrated on the upper surface. However, in a certain area of fine pulverized product, fine pulverized product has few normal cells and is most likely to be deformed by compression (easily crushed). Since a layer that is difficult to bring about is formed, stress applied by vibration or the like is dispersed in the portion where the device is placed and the concentrated load is reduced, so that deformation can be made difficult.
[0095]
On the pressure-receiving surface side of the obtained buffer material 21, the finely pulverized product 29 and more adhesive than usual are provided and solidified, so that there is a dense layer with few voids between the pulverized particles. When the surface layer portion and the center layer portion of the cushioning material 21 were collected and the compression characteristics thereof were measured, as shown in Table 5, the surface layer on the pressure receiving surface side of the cushioning material was about 2 in comparison with the center portion. It was found that double strength and rigidity were obtained.
[0096]
[Table 5]

[0097]
Here, in the mixture of the finely pulverized product 29 and the adhesive forming the surface layer, in the present embodiment, a semi-cured powdery epoxy resin is used as the adhesive, but instead of this, a liquid adhesive is used. Also good. That is, by mixing the finely pulverized product 29 and the liquid adhesive, a paste-like mixture is obtained, and thus the nonwoven fabric 22 is placed along the lower mold (S-13) uniformly in the mold. (S-14a) is also effective and is an effective method for obtaining the same mode.
[0098]
As described above, the finely pulverized product 29 is arranged on the pressure-receiving surface side of the mold and the coarse pulverized product 30 which is different pulverized products is laminated and molded, and the finely pulverized product 29 is bonded more than usual. Since it is solidified with the agent, it is possible to easily obtain a cushioning material for a molded product having a surface layer portion with high rigidity and strength.
[0099]
Embodiment 4 FIG.
The present embodiment relates to claims 12 and 13 of the present invention, and will be described below based on the illustrated embodiment. FIG. 13 is a process diagram showing a method of reclaiming a used molded cushioning material, and FIG. 14 is a conceptual diagram showing an arrangement state of the used cushioning material in a mold.
[0100]
The shock absorbing material 21 shown in FIG. 14 is greatly deformed due to repeated stress and impact applied to the pressure receiving surface 31, but there is almost no damage to the anti pressure receiving surface 32 such as fixing to the packing base plate. Therefore, when the used molded cushioning material 34 is put into the mold 33 used before use, a gap 35 is formed on the pressure receiving surface 31 side. By placing the used cushioning material 34 after the mixture 36 of the pulverized material and the adhesive is put into the mold 33 arranged with the portion corresponding to the pressure receiving surface 31 of the cushioning material 21 facing down. The gap 35 is filled with the mixture 36 and solidified to ensure the original shape.
[0101]
Next, the regeneration method will be described with reference to the process chart of FIG. 13 showing the cushioning material regeneration method. First, in a mold 33 with a pressure-receiving surface 31 portion of a used cushioning material 34 disposed below, a powdered product is formed with a pulverized product obtained by pulverizing urethane foam, which is a heat insulating material of a refrigerator, to a size of 1 to 5 mm, for example. A mixture 36 obtained by premixing (S-21) the adhesive which is a semi-cured epoxy resin at a weight ratio of 100: 20 is charged (S-22).
[0102]
The mixture 36 is charged with a weight (apparent density) with respect to the original volume of the buffer material 34 and a weight obtained from the approximate void volume. On the charged mixture 36, as shown in the conceptual diagram of FIG. Then, the used cushioning material 34 is placed (S-23), and a die (not shown) on the side of the pressure-receiving surface 32 is combined (S-24). Next, the mold 33 is inverted (S-25) and held so that the mixture 36 of the pulverized product and the adhesive present in the inside exhibits a uniform dispersion state in the non-uniform voids caused by the damage.
[0103]
The mold 33 was heated to 140 ° C. at a rate of 50 ° C./min or more, and was further sealed by applying a further load to the mold 33 and solidified by holding for 10 minutes (S-26). (S-27), the cushioning material 21 was repaired with a damaged portion of the pressure receiving surface 31 provided with a solidified mixture of urethane foam and adhesive 36 in a dense state.
[0104]
Further, according to the above-described method, the pulverized material and the pulverized material can be used according to the size of the gap 35 formed between the used buffer material 34 put into the mold 33 without using the same buffer material. Since the shape part which is lacking by the adhesive mixture 36 can be filled and molded, the used cushioning material of the present invention may be used as a pulverized product.
Further, in the present embodiment, when the portion lacking the shape is repaired, the nonwoven fabric is not placed on the inner surface of the mold 33. After mounting along line 33, step S-22 and subsequent steps may be performed, and after removing step S-27, unnecessary portions of the nonwoven fabric may be deleted for repair.
[0105]
As described above, according to the above method according to the present invention, a used cushioning material can be easily regenerated and restored to its original shape without subjecting the cushioning material to pulverization again.
[0106]
As described above, in each embodiment of the present invention, the molded cushioning material and the molding method thereof have been described. However, the present invention is not limited to this, and for example, a refrigerator, a cold car or a building. It can be used as an alternative to conventional foamed resin applications, such as heat insulation materials used for heat insulation and cold insulation, and structural materials used in the middle of plate materials in lightweight and high-rigidity structures. Various modifications can be made without departing from the scope.
[0107]
【The invention's effect】
  The cushioning material according to the first aspect of the present invention covers a nonwoven fabric in which fibers are held in a non-linear and disordered orientation state, and a mixture obtained by mixing a pulverized product of foamed resin and an adhesive with the nonwoven fabric. A buffer layer molded byIn the buffer layer, at least in the vicinity of the pressure-receiving surface where pressure is applied, the foamed resin cell is deformed and crushed by molding, and forms a rigid layer.The brittleness of the surface can be compensated to prevent a part of the molded product from being lost, and it can be easily discarded without generating harmful gas for the combustion after the disposal process.In addition, when a device is placed and it receives an impact force, this layer creates an action to disperse the stress on the pulverized material underneath, so that it does not receive a large stress locally. Therefore, it is possible to obtain a feature that the molded product that is the buffer material is difficult to be deformed.
[0109]
  First of the present invention2In the cushioning material according to the invention, the pulverized foam resin is different in particle size, and the smaller one of the foamed resin pulverized products is arranged on the pressure-receiving surface side of the buffer layer. In addition, when this is subjected to impact force, this rigid layer exerts the effect of dispersing the stress on the pulverized material underneath it, so that it is not subjected to large local stress, and therefore is a cushioning material. It is possible to obtain a feature that the product is difficult to deform.
[0110]
  First of the present invention3In the cushioning material according to the invention, the cushioning layer includes an excess adhesive that does not contribute to adhesion in the gaps between the pulverized foamed resins, so that the gap near the mold surface at the lower position during molding is reduced. And can be used to form a highly rigid layer.
[0111]
  First of the present invention4Since the cushioning material according to the invention includes bubbles that communicate with the buffer layer, it suppresses the behavior of absorbing and repelling distortion caused by the applied stress, and therefore the cushioning characteristics can be improved.
[0112]
  First of the present invention5In the cushioning material according to the invention, since the pulverized product of the foamed resin is provided with bubbles that communicate with each other, when the gas in the cell expands at a high temperature, it is exhausted to the same pressure as the outside air. By maintaining it, it is possible to suppress the dimensional expansion of the heat insulating wall body, and it is possible to suppress the occurrence of excessive repulsive force by discharging gas such as air in the cell at the time of compressive deformation due to impact during transportation.
[0113]
  According to a sixth aspect of the present invention, there is provided a cushioning material manufacturing method comprising: placing a nonwoven fabric on a lower mold; and placing the nonwoven fabric on a mixture of a pulverized product containing a foamed resin and a powdery adhesive. The step of putting in the lower mold, the step of placing the non-woven fabric on the mixture, the step of placing the upper die on the mixture, and the pressure receiving surface side to which pressure is applied in the mixture Heating above the deformation temperature, heating the pressure-receiving surface side below the thermal deformation temperature of the foamed resin above the melting point of the adhesive, and molding the adhesive after meltingThe foamed resin cell in the vicinity of the pressure-receiving surface is deformed and crushed by molding to form a rigid buffer layer.Even if the pressure-receiving surface is in a state of high rigidity in a mode close to a non-foaming state, the other part is provided with a foamed resin having excellent cushioning characteristics, and has excellent smoothness in appearance. Goods are obtained.
[0114]
  According to a seventh aspect of the present invention, there is provided a cushioning material manufacturing method comprising: placing a non-woven fabric on a lower mold; and mixing a mixture of a pulverized product containing a foamed resin and an adhesive with a surface forming a pressure-receiving surface below. A step of throwing the nonwoven fabric placed at a position into the lower mold, a step of vertically moving the mixture put into the lower mold, and a nonwoven fabric after or before the step. A step of placing the upper mold on the substrate, and a mixture provided with the vertical movementAmong these, at least the pressure-receiving surface vicinity where pressure is applied is equal to or higher than the thermal deformation temperature of the foamed resin.Molding after heating and melting the adhesive at a temperature at which the foamed resin does not melt or decomposeAnd the foamed resin cell is deformed and crushed by molding to form a rigid buffer layer.And a process ofTherefore, a pulverized product with a small particle diameter that is easily crushed by compression and an excessive adhesive gather on the pressure receiving surface to achieve communication between the highly rigid pressure receiving surface and air bubbles, and a smooth resin with a foamed resin with excellent buffering characteristics. A molded product with an appearance can be obtained.
[0115]
  First of the present invention8In the cushioning material manufacturing method according to the invention, the vertical movement is performed by applying vibration, so that the vertical movement with the gap is achieved by shocking fine vibration when dropped, so that the pulverized material is shrunk to impair the appearance. It is difficult to obtain a molded product having excellent appearance smoothness.
[0116]
  According to a ninth aspect of the present invention, there is provided a cushioning material manufacturing method comprising: a step of classifying a pulverized product of a foamed resin for each predetermined particle size; and a mixture obtained by mixing each of the classified pulverized product and an adhesive. A step of obtaining, a step of placing the nonwoven fabric on the lower mold, and a step of sequentially charging the lower mold on which the nonwoven fabric is placed so that the mixture having a small particle size is disposed at a position where the pressure receiving surface is formed. Placing the nonwoven fabric on the mixture and placing an upper mold thereon,At least near the pressure-receiving surface where pressure is applied, at or above the heat deformation temperature of the pulverized foam resin,Molding the mixture by heating to a temperature at which the pulverized foamed resin does not melt or decomposeAnd the foamed resin cell is deformed and crushed by molding to form a rigid buffer layer.A molded product that is less likely to be deformed by dispersing the applied stress in the surface direction.
[0117]
  First of the present invention10In the method of manufacturing the cushioning material according to the invention, since the foamed resin pulverized product has a diameter of not less than 3 times the diameter of the foamed resin foam and not more than 10 mm, the foam can be efficiently communicated. Therefore, a molded product having excellent buffer characteristics and appearance can be obtained.
[Brief description of the drawings]
FIG. 1 is a perspective view of a cushioning material showing a first embodiment of the present invention.
FIG. 2 is a cross-sectional view of FIG.
FIG. 3 is a conceptual diagram showing an example in which the cushioning material according to the first embodiment of the present invention is used in the upper part of the product.
FIG. 4 is a manufacturing process diagram showing a manufacturing method of the cushioning material according to the first embodiment of the present invention.
FIG. 5 is an explanatory view showing a cushioning material forming method according to the first embodiment of the present invention.
FIG. 6 is a manufacturing process diagram showing a manufacturing method of a cushioning material according to a second embodiment of the present invention.
FIG. 7 is a cross-sectional view showing the structure of a refrigerator provided with a heat insulating material to be pulverized.
FIG. 8 is a conceptual diagram showing a bubble structure of a heat insulating material.
FIG. 9 is a relationship diagram of temperature and dimensional change measured using a thermodynamic analyzer (TMA).
FIG. 10 is a manufacturing process diagram illustrating a manufacturing method of a cushioning material according to a second embodiment of the present invention.
FIG. 11 is a cross-sectional view showing an internal structure of a cushioning material according to a third embodiment of the present invention.
FIG. 12 is a manufacturing process diagram illustrating a manufacturing method of a cushioning material according to a third embodiment of the present invention.
FIG. 13 is a manufacturing process diagram showing a manufacturing method of the cushioning material according to the fourth embodiment of the present invention.
FIG. 14 is a conceptual diagram showing an arrangement state of used cushioning materials on a mold by the manufacturing method according to the fourth embodiment of the present invention.
FIG. 15 is an external view of a cushioning material obtained by integrating conventional pulverized materials.
[Explanation of symbols]
  3 pulverized product of foamed resin, 4 adhesive, 21 cushioning material (molded product), 22 non-woven fabric, 27 cell membrane, 28 strut portion, 29 fine pulverized product, 30 coarse pulverized product, 31 receiptPressure side, 32AntiPressure-receiving surface, 34 Used buffer material, 36, 40 Mixture of foamed resin pulverized product and adhesive, 41 Buffer layer.

Claims (10)

A non-woven fabric in which fibers are held in a non-linear and disordered orientation state, and a buffer layer formed by covering the non-woven fabric with a mixture obtained by pulverizing a foamed resin and a mixture of an adhesive, and
The buffer material is characterized in that at least in the vicinity of a pressure receiving surface to which pressure is applied, the cell of the foamed resin is deformed and crushed by molding to form a rigid layer.   2. The cushioning material according to claim 1, wherein the pulverized foamed resin is different in particle size, and the pulverized foamed resin has a smaller particle diameter disposed on the pressure-receiving surface side of the buffer layer.   The cushioning material according to claim 2, wherein the cushioning layer includes an excess adhesive that does not contribute to adhesion in a space between the foamed resin pulverized products.   The buffer material according to claim 1, wherein the buffer layer includes bubbles that communicate with each other.   The cushioning material according to claim 1 or 2, wherein the pulverized product of the foamed resin is provided with air bubbles connected to each other. Placing the nonwoven fabric on the lower mold; and
Introducing a mixture of a pulverized product containing a foamed resin and a powdered adhesive into the lower mold on which the nonwoven fabric is placed;
Placing a non-woven fabric on the mixture and placing an upper mold thereon;
The pressure-receiving surface side to which pressure is applied in the mixture is heated to a temperature higher than the thermal deformation temperature of the foamed resin, and the side opposite to the pressure-receiving surface is heated to a temperature lower than the thermal deformation temperature of the foamed resin to a temperature equal to or higher than the melting point of the adhesive. Molding after melting the agent, the foamed resin cell in the vicinity of the pressure-receiving surface is deformed and crushed by molding, forming a rigid buffer layer ;
A method for producing a cushioning material, comprising: Placing the nonwoven fabric on the lower mold; and
A step of introducing a mixture of a pulverized product containing a foamed resin and an adhesive into the lower mold on which the non-woven fabric is placed with the surface forming the pressure-receiving surface positioned below;
Applying vertical movement to the mixture charged in the lower mold;
Placing a non-woven fabric on the mixture after or before the step, and placing an upper mold thereon;
Of the mixture provided with the vertical movement , at least the vicinity of the pressure-receiving surface to which pressure is applied is heated to a temperature higher than the thermal deformation temperature of the foamed resin, and the adhesive is melted at a temperature at which the foamed resin does not melt or decompose. Molding the foamed resin cell so that the foamed resin cell is deformed and crushed to form a rigid buffer layer ;
A method for producing a cushioning material, comprising:   The method for manufacturing a cushioning material according to claim 7, wherein the vertical movement is performed by applying vibration. A step of classifying the pulverized foamed resin for each predetermined particle size;
Obtaining a mixture in which each of the classified pulverized product and the adhesive is mixed; and
Placing the nonwoven fabric on the lower mold; and
Sequentially feeding the lower mold on which the nonwoven fabric is placed so that the mixture having a small particle size is disposed at a position where a pressure receiving surface is formed;
Placing a non-woven fabric on the mixture and placing an upper mold thereon;
At least the pressure-receiving surface in the vicinity of the pressure is heated to a temperature that is equal to or higher than the thermal deformation temperature of the pulverized product of the foamed resin, and the pulverized product of the foamed resin is not melted or decomposed to form the mixture , The cell is deformed and crushed by molding to form a rigid buffer layer ;
A method for producing a cushioning material, comprising:   The cushioning material according to any one of claims 6 to 9, wherein the foamed resin pulverized product has a diameter of not less than 3 times the diameter of foamed resin bubbles and not more than 10 mm. Method.

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