JPWO2002053474A1

JPWO2002053474A1 - Buffer for glass substrate and package using the buffer

Info

Publication number: JPWO2002053474A1
Application number: JP2002554602A
Authority: JP
Inventors: 上田　康; 浜田　逸男
Original assignee: Asahi Kasei Life and Living Corp
Current assignee: Asahi Kasei Life and Living Corp
Priority date: 2000-12-27
Filing date: 2001-12-26
Publication date: 2004-04-30
Anticipated expiration: 2021-12-26
Also published as: KR100552879B1; CN1482985A; JP4091432B2; WO2002053474A1; DE10197125B3; CN1222449C; KR20030093192A

Abstract

本発明は、Ｌ字形の断面を有し、Ｌ字の端部の厚さが角部よりも厚いガラス基板用緩衝体に関する。厚さに関する上記要件を満たすための具体的な構成として以下のものを包含する。（１）固定具案内溝の深さをＬ字の端部から角部に向けて深くなるように形成することにより、該固定具案内溝の底部を基準とした緩衝体の厚さをＬ字の端部から角部に向けて漸減させる。（２）固定具案内溝を形成せず、緩衝体自体の厚みがＬ字の両端部から角部に向かって漸減するように緩衝体を成形する。（３）緩衝体のＬ字の外側の両端部に凸部を形成する。本発明の緩衝体によると固定具で締結した際に、固定具の締結力の角部への集中が防止される。The present invention relates to a buffer for a glass substrate having an L-shaped cross section, wherein the thickness of the end of the L-shape is larger than that of a corner. Specific configurations for satisfying the above requirements regarding the thickness include the following. (1) By forming the depth of the fixture guide groove so as to increase from the end of the L-shape toward the corner, the thickness of the buffer with respect to the bottom of the fixture guide groove is L-shaped. From the end to the corner. (2) The buffer is formed such that the thickness of the buffer itself decreases gradually from both ends of the L-shape toward the corners without forming the fixing tool guide groove. (3) Protrusions are formed at both ends outside the L-shape of the buffer. ADVANTAGE OF THE INVENTION According to the buffer of this invention, when it fastens with a fixture, concentration of the fastening force of a fixture to a corner part is prevented.

Description

＜技術分野＞
本発明は、ガラス基体上に半導体装置等電子部品を形成してなるガラス基板を、輸送時の振動等による損傷から保護する搬送用の緩衝体と、該緩衝体を用いて上記ガラス基板を複数枚同時に梱包した包装体に関する。
＜背景技術＞
近年、電子・電気関連機器、特にパーソナルコンピュータの周辺機器の一つである液晶ディスプレイやプラズマディスプレイ、携帯電話に代表される携帯端末等は、インターネットに代表される情報技術産業の発達と共に生産量が急激な勢いで伸長している機器であり、その梱包や搬送等に用いられる緩衝体関連技術の開発が強く望まれている。中でも、半導体装置等の電子部品を組み込んだガラス基板、例えばカラーフィルターやＴＦＴ液晶セル（薄膜トランジスタを組み込んだ回路が形成された基板）及び液晶パネル等に用いられているガラス基板はその厚さが薄く、輸送中における衝撃や振動等に弱い上、その構成が非常に微細なため、外部からの影響を受け易く、取り扱いが難しい。とりわけ、加工前のガラス基板や最終製品になる前の半完成品を搬送する場合には、上記電子部品が剥き出しの状態で扱われるため、静電気や塵、埃等の影響をより強く受け、その機能を損なう場合があった。
そこで、ガラス基板を損傷することなく安全に搬送するための梱包技術が多々提案されている。
その一例として、特開平５−３１９４５６号公報に開示された技術が挙げられる。その要点は、断面が略Ｌ字形を呈し、該Ｌ字に沿って内側には基板挿入溝を複数設けた、特定の特性を有するポリオレフィンビーズ発泡体からなる緩衝体である。ガラス基板の梱包に当たっては、複数のガラス基板を所定の間隔をもって平行配置して直方体を形成し、各基板の角部をそれぞれ上記緩衝体の基板挿入溝に挿入し、該基板表面に対して直交する上記直方体の４辺を上記緩衝体により嵌合し、さらに、必要に応じてゴムやテープ等の固定具で固定する。
しかしながら、緩衝体の外側にゴムやテープ等の固定具をかけて固定した場合、その締結力が該緩衝体の角部に集中するため、Ｌ字が開いてその両端部においてはガラス基被が基板挿入溝よりはずれてしまい、保護機能が十分に働かないという問題を生じる場合があった。
また、前記したＬ字形の緩衝体は、基板挿入溝の溝幅がガラス基板の厚みと同等かもしくは若干狭い幅で形成され、ポリオレフィンビーズ発泡体の特性である圧縮時の弾性回復性の高さを利用して、ガラス基板を固定するものである。そのため、搬送中のガラス基板との振動摩擦による耐発塵性には効果的であるが、本来の目的であるガラス基板の梱包に際しては、ガラス基板との摩擦抵抗が逆効果となって、無理にガラス基板を基板挿入溝にはめ込もうとすると、０．４〜１．０ｍｍ程度と極めて薄いガラス基板が容易に撓んで破損し易く、破損を避けるべく慎重に作業を行うと時間が長くかかるという問題を生じている。これはガラス基板の取り出しに際しても同様である。特に最近は省力化の点からガラス基板の自動収納装置、取り出し装置の導入が進んでいるが、上記の問題からトラブルが発生し易く、現実問題として自動化には適していないという指摘もある。
さらに、ガラス基板を基板挿入溝に挿入する際に、摩擦抵抗力からガラス基板表面に微細な擦り傷が発生する場合もあり、問題となっている。
本発明の課題は、上記問題点に鑑み、ガラス基板梱包時に緩衝体のＬ字の端部におけるガラス基板の溝はずれがなく、搬送中や取り扱い時に振動や落下衝撃等の外力が加わってもガラス基板を安全に保護することができるガラス基板用緩衝体を提供することにあり、さらには、ガラス基板の収納、取り出しの自動化に適し、ガラス基板と摺擦しても容易に粉塵を発生せず、耐久性に優れて複数回の使用が可能なガラス基板用緩衝体を提供し、これら緩衝体を用いて梱包した包装体を提供することにある。
＜発明の開示＞
本発明の第一のガラス基板用緩衝体は、ポリオレフィンビーズ発泡体からなるガラス基板用緩衝体であって、ガラス基板の角部の形状に従って略Ｌ字形の断面を有し、該Ｌ字に沿って内側表面にはガラス基板の角部を形成する２側端を固定する基板挿入溝が複数本設けられており、外側表面には該Ｌ字に沿って形成された少なくとも１本の固定具案内溝を有し、該固定具案内溝の底部を基準とした当該緩衝体の厚さがＬ字の両端部から角部に向かって漸減しているものである。
上記本発明の第一のガラス基板用緩衝体は、角部における固定具案内溝の底部が面取りされていることを好ましい態様として含むものである。
本発明の第二のガラス基板用緩衝体は、ポリオレフィンビーズ発泡体からなるガラス基板用緩衝体であって、ガラス基板の角部の形状に従って略Ｌ字形の断面を有し、該Ｌ字に沿って内側表面にはガラス基板の角部を形成する２側端を固定する基板挿入溝が複数本設けられており、当該緩衝体の厚みがＬ字の両端部から角部に向かって漸減しているものである。
本発明の第三のガラス基板用緩衝体は、ポリオレフィンビーズ発泡体からなるガラス基板用緩衝体であって、ガラス基板の角部の形状に従って略Ｌ字形の断面を有し、該Ｌ字に沿って内側表面にはガラス基板の角部を形成する２側端を固定する基板挿入溝が複数本設けられており、該Ｌ字の外側の両端部に凸部が形成されているものである。
上記本発明の第二及び第三のガラス基板用緩衝体は、外側の角部が面取りされていることを好ましい態様として含むものである。
また、上記本発明のガラス基板用緩衝体は、内側に、基板挿入溝に直交する方向に切り欠き溝を有すること、緩衝体の最大厚みが１０〜６０ｍｍ、Ｌ字の２辺の比が短辺基準で１．０〜３．０であり、基板挿入溝の溝幅がガラス基板の厚みの１．０〜４．０倍、溝深さが３〜１５ｍｍ、溝ピッチが６〜１００ｍｍであること、ポリオレフィンビーズ発泡体が、発泡粒子の平均粒子径が１．５〜５．０ｍｍ、融着率が７０％以上、圧縮弾性指数が３．９〜４９０、回復率が６０％以上であること、を好ましい態様として含むものである。
また、本発明の第一の包装体は、複数のガラス基板を所定の間隔をもって平行配置して直方体を形成し、各基板の角部をそれぞれ本発明の第一のガラス基板用緩衝体の基板挿入溝に挿入して該基板表面に対して直交する上記直方体の４辺を上記緩衝体により嵌合し、該緩衝体の固定具案内溝に沿って長尺の固定具を巻回して締結したことを特徴とする。
さらに、本発明の第二の包装体は、複数のガラス基板を所定の間隔をもって平行配置して直方体を形成し、各基板の角部をそれぞれ本発明第二或いは第三のガラス基板用緩衝体の基板挿入溝に挿入して該基板表面に対して直交する上記直方体の４辺を上記緩衝体により嵌合し、該緩衝体の外側にＬ字に沿って長尺の固定具を巻回して締結したことを特徴とする。
＜発明を実施するための最良の形態＞
本発明の緩衝体は、ポリオレフィンビーズ発泡体からなる断面が略Ｌ字形の緩衝体において、該Ｌ字の端部の厚さを角部に比べて厚く形成したことに特徴を有し、これにより、ガラス基板を梱包してその外側を固定具により締結した際に、該Ｌ字の端部においては固定具が角部よりも外側を通ることになり、固定具の締結力が角部に集中するのを避け、緩衝体全体を均等に押圧してガラス基板を保護することができる。
本発明において、緩衝体のＬ字の端部の厚さを角部よりも厚くする具体的な構成は以下の通りである。
（１）固定具案内溝の深さをＬ字の端部から角部に向けて深くなるように形成することにより、該固定具案内溝の底部において緩衝体の厚さをＬ字の端部から角部に向けて漸減させる。
（２）固定具案内溝を形成せず、緩衝体自体の厚みがＬ字の両端部から角部に向かって漸減するように緩衝体を成形する。
（３）緩衝体のＬ字の外側の両端部に凸部を形成する。
以下に本発明の緩衝体及び該緩衝体を用いて複数のガラス基板を一体に梱包した包装体について、実施形態を挙げて具体的に説明する。
図１は上記（１）の構成を備えた本発明の緩衝体の一実施形態の斜視図である。図中、１は緩衝体、２は基板挿入溝、３は固定具案内溝、４は隣接する基板挿入溝２間を隔てる凸条を示す。また、当該緩衝体を４個用いて複数のガラス基板を梱包した本発明の包装体の一実施形態の斜視図を図２に示す。図中、２１はガラス基板、２２は固定具であり、図１と同じ部材には同じ符号を付した。
本発明の緩衝体１は、ガラス基板２１の角部を保護し、且つ、複数枚を一体固定するものであるが、２個以上、好ましくは４個一組で梱包を行う。
図１に示すように、本発明の緩衝体１は、ガラス基板の角部の形状に従って断面が略Ｌ字形を呈し、ガラス基板の角部を形成する２側端を固定するべく該Ｌ字に沿って基板挿入溝２が複数本、互いに凸条４に隔てられて設けられている。
また、前記（１）の構成を備えた場合には、Ｌ字に沿って固定具案内溝３が形成されている。固定具案内溝３は、図２に示すように、ガラス基板２１を梱包した後、固定具２２を該案内溝３に沿って巻回するためのもので、本発明において該固定具案内溝３を設ける場合には、その底部において緩衝体１の厚みが角部に向けて漸減するように深さに変化を付ける。図３（ａ）に図１の緩衝体１の固定具案内溝３及び基板挿入溝２に沿った断面を模式的に示す。図３において、３１は緩衝体１の外側壁面、３２は基板挿入溝２の底面、３３は緩衝体１のＬ字の端部、３４、３４’はＬ字の角部、３５は固定具案内溝３の底部、３６は面取り部、３７は切り欠き溝、３８は凸部、３９は凹部である。尚、下記の説明において、角部３４或いは３４’における厚みとは、Ｌ字の内側の角部における、緩衝体短辺及び長辺の厚みをさす。
図３（ａ）に示すように、固定具案内溝の深さをＬ字の端部３３においては浅く、角部３４’においては深くなるように形成することによって、該固定具案内溝の底部３５における緩衝体の厚さはＬ字の端部３３から角部３４’に向かって漸減する。その結果、ガラス基板を梱包した後に固定具案内溝に沿って長尺の固定具を巻回した際に、角部３４’よりも端部３３において固定具からガラス基板までの距離が大きくなり、固定具の締結力が角部３４’に集中するのを防ぐことができる。
また、固定具の締結力が固定具案内溝の底部３５の角部３４’に集中するのを避けるべく、図３（ｂ）に示すように、予め面取りをして面取り部３６を形成しておくことも好ましい。面取り部３６を形成することで、固定具が緩衝体に食い込んで損傷させる恐れが無くなり、角部３４’における変形歪みが小さくなり、緩衝体の端部３３が外側に開きにくくなる。面取り部３６は平面形状でも湾曲形状でも良い。
さらに、図３（ｃ）に示すように、緩衝体の内側に、基板挿入溝に直交する方向（紙面に直交する方向）に切り込み、切り欠き溝３７を１本以上設けることにより、固定具による締結時に端部３３が外側に開こうとする変形応力を該切り欠き溝３７が吸収して端部３３に伝播させないようにすることができ、好ましい。尚、切り欠き溝３７の形状としては、図３（ｃ）に示される略Ｖ字形の他に、略Ｕ字形などでも良い。
また、図３においては、短辺側の角部３４内側において、凸条４が部分的に除去された凹部３９が形成されているが、これは、搬送中の振動衝撃や落下衝撃を受けた場合に最も容易に損傷するガラス基板角部の欠損を防止するための構成である。尚、凹部３９においては凸条４を基板挿入溝の底部３２に達するまで除去すれば良い。また、ガラス基板角部の欠損を防止する観点からは、底部３２よりもさらに深く形成することが好ましい。
本発明において、緩衝体のＬ字の端部３３を角部３４よりも厚くする構成として、前記した構成（２）の一例を図３（ｄ）に、構成（３）の一例を図３（ｅ）に示す。図３（ｄ）においては、緩衝体自体の厚みをＬ字の端部３３から角部３４に向かって漸減するように成形している。この場合、特に固定具案内溝を形成しないため、固定具の幅及び巻回位置を自由に選択することができる。また、図３（ｅ）においては、緩衝体の厚みは均一であるが、Ｌ字の端部３３の外側に凸部３８が形成され、結果として、該端部３３における緩衝体の厚みが角部３４よりも厚くなっている。凸部３８は、本体と一体成形しても良いが、別途板状に成形したものを後から熱融着や接着剤により接着で本体に取り付けても良く、その場合には、本体と同じ素材であっても異なる素材であっても構わない。
図３（ｄ）、（ｅ）の構成においても、図３（ｂ）、（ｃ）に示したような面取り部３６や切り欠き溝３７を適宜取り入れることが可能である。
次に、本発明の緩衝体の好ましい外形寸法について説明する。
本発明の緩衝体における、Ｌ字の２辺（ガラス基板が接する部分の長さ）の比は短辺基準で１．０以上が好ましく、より好ましくは３．０以下がよい。この範囲であると、長辺と短辺のバランスがよく、矩形のガラス基板の固定安定性が非常によくなる。また、ガラス基板が撓んで損傷する確率もより低くなる。さらに好ましくは２．７未満である。
また、上記範囲内において、短辺の長さは梱包するガラス基板の短辺の長さの１０％以上が好ましく、より好ましくは４５％以下がよい。更には、１５％以上が好ましく、４０％以下であると最も好ましい。緩衝体の短辺の長さが上記の範囲であると、例え落下衝撃等を受けても、その衝撃力を充分に吸収する緩衝体が配置されているので、ガラス基板が損傷する危険性を回避できる。また、緩衝体に係る応力（ガラス基板の自重）を低くできるので搬送中の振動による接触摩擦での発塵が抑えられ、清浄性も満足できるものとなる。
具体的な外形寸法としては、短辺が１００ｍｍ以上が好ましく、より好ましくは５００ｍｍ以下がよい。長辺は１００ｍｍ以上が好ましく、より好ましくは１５００ｍｍ以下がよい。また、該短辺、長辺に直交する方向の長さはガラス基板の収納枚数にもよるが、１５０ｍｍ以上が好ましく、より好ましくは６００ｍｍ以下がよい。
本発明の緩衝体の最大厚みは、ガラス基板のサイズ、重量、梱包枚数、圧縮弾性指数等を鑑みると、最大厚さが１０ｍｍ以上が好ましく、より好ましくは６０ｍｍ以下がよい。さらに好ましくは、１５ｍｍ以上、及び／または４０ｍｍ以下である。外形寸法及び最大厚みが上記の範囲であると、加工前のガラス基板は勿論のこと各種寸法のガラス基板製品全てを安定して固定できる搬送用緩衝体として用いることができる。また、搬送時の衝撃にも充分に耐えるガラス基板保護機能が発揮できる。
また、図３（ａ）の如く固定具案内溝を形成した場合には、その深さが端部３３において０．５ｍｍ以上が好ましく、より好ましくは５ｍｍ以下、更に角部３４’では２ｍｍ以上が好ましく、より好ましくは１５ｍｍ以下である。この範囲になるように固定具案内溝の深さを形成すると、固定具の位置ずれは勿論なく然も固定具で締結固定した時に締結力が緩衝体の短辺及び長辺の全面に渡って均等に加わるために緩衝体の開脚変形が防げてガラス基板４箇所の角部を安定して固定できることから、ガラス基板の保護機能を充分に満足する。また、図３（ａ）では固定具案内溝は端部３３まで形成されているが、端部３３付近では緩衝体の外壁３１と同一平面となるように形成してもよく、この場合、固定具案内溝は端部３３から１０ｍｍ以上隔てることが好ましく、より好ましくは端部３３から１００ｍｍ以下の位置から角部３４’に向かって徐々に深くなるように形成することがより好ましい。この範囲であると搬送中にも固定具の位置ずれがなく然も上記の端部３３から該案内溝を形成したのと同等の効果が得られる。
さらに、図３（ｄ）のように緩衝体自体の厚みを変える場合には、角部３４の厚みが端部３３の厚みより１ｍｍ以上薄くすることが好ましく、より好ましくは１０ｍｍ以下である。更に好ましくは、３ｍｍ以上、最も好ましくは８ｍｍ以下である。また、この場合も、端部３３より角部３４方向に１０ｍｍ以上、より好ましくは１００ｍｍ以下の位置までは端部３３の厚みでもって均一な厚みに形成し、該位置より角部３４までの厚さを漸減的に変化させても上記と同様の効果は得られる。
また、図３（ｅ）の場合には、角部３４の厚みが端部３３の厚みより１ｍｍ以上薄くすることが好ましく、より好ましくは１０ｍｍ以下がよい。角部３４が薄くなる手段としては図３（ｅ）に示すように端部３３近傍に凸部３８を形成することで達成できる。また、この凸部３８のＬ字に沿った方向の幅は１０ｍｍ以上が好ましく、さらに好ましくは１００ｍｍ以下がよい。より好ましくは、２０ｍｍ以上、最も好ましくは８０ｍｍ以下である。
さらにまた、図３（ｂ）に示す面取り部３６を形成する場合には、緩衝体の圧縮弾性指数、最大厚み、両辺の長さ等を鑑みて、Ｌ字断面において、円弧状或いは直線状でもって長さは３ｍｍ以上が好ましく、より好ましくは６０ｍｍ以下に形成する。
面取りがこの範囲であると、ガラス基板を梱包してその外側を固定具により締結した際に、固定具の締結力が角部に集中するのが避けられるために、緩衝体全体を均等に押圧してガラス基板角部を固定できる。従って、ガラス基板の固定、保護機能が一層高まると共に強い締結力で固定具を巻回しても緩衝体に該固定具が切れ込んで食い込むといった現象が無くなり、何回も長期間に渡って繰り返し再使用ができるので耐久性が格段に向上する。
また、図３（ｃ）の切り欠き溝３７を形成する場合には、溝深さが該切り欠き溝３７を形成する部分における緩衝体厚みの１／２０以上が好ましく、より好ましくは１／２以下がよい。更に該溝幅は２ｍｍ以上が好ましく、より好ましくは１０ｍｍ以下がよい。尚、切り欠き溝３７の位置及び本数は、特に限定されるものではないが、角部（短辺及び長辺のガラス基板が接する部分の接点）より辺長（ガラス基板が接する部分の長さ）の１／８以上が好ましく、より好ましくは４／５以下の部位に１本以上が好ましく、より好ましくは３本以下がよい。切り欠き溝３７を上記範囲に形成すると緩衝体の剛性を損なうことなくガラス基板挿入溝の全長に渡ってガラス基板の挿入固定性がしっかりしたものとなることから基板の保護機能が向上し、然も緩衝体の摩擦発塵性もより低くなる効果が派生する。
さらに、図３の凹部３９を形成する場合には、凹部３９の底部が基板挿入溝の底部３２に達するように設定することが好ましく、より好ましくはガラス基板の大きさや厚み、緩衝体の最大厚みを鑑みて、基板挿入溝の底部３２から１ｍｍ以上、最も好ましくは、８ｍｍ以下の深さ、最も好ましくは２ｍｍ以上、最も好ましくは、６ｍｍ以下の深さに形成するのがよい。この範囲であると、落下衝撃等で緩衝体が歪み変形を生じても最も脆弱なガラス基板角部に外力が加わらないために損傷する確率が極めて低くなる。また、緩衝体の構造強度も充分に保持できるために繰り返し使用しても初期の形状が維持できる。従ってガラス基板の固定、保護機能が長期に渡って発揮できる。
本発明の緩衝体に形成された基板挿入溝の溝幅は、梱包するガラス基板の厚みの１．０倍以上、４．０倍以下が好ましく、より好ましくは１．２倍以上、３．５倍以下がよい。この範囲であると、手動或いは自動装置でのガラス基板の挿入、取り出し作業が速く効率よく行え、然も挿入作業でのガラス基板の破損トラブル激減する。また、基板挿入溝部でのガラス基板の固定性も充分であるので搬送中に振動衝撃を受けてもガラス基板と緩衝体との摩擦が押さえられ発塵現象が極めて低く、ガラス基板の清浄性が保てる。
また、基板挿入溝の深さは、ガラス基板のサイズ、重量、及び緩衝体の圧縮弾性指数、基板挿入溝の溝幅等を鑑みて、３ｍｍ以上が好ましく、より好ましくは１５ｍｍ以下がよい。さらに好ましくは、５ｍｍ以上最も好ましくは１０ｍｍ以下である。この範囲であると、搬送中に振動衝撃や取り扱いでの落下衝撃を受けてもガラス基板を挿入溝に挿入した状態で確実に固定できることから、ガラス基板が挿入溝から外れて隣りの基板と接触すると云った損傷事故が防止できる。また、ガラス基板が基板挿入溝と接触する部分は、搬送中の振動衝撃で常に緩衝体と摺擦しているので、該ガラス基板表面には微細な擦り傷が発生している可能性が極めて高いことから例えば搬送したガラス基板を液晶パネル等に加工する場合は、予め緩衝体の基板挿入溝と接触していた該基板部を切断除去してから用いるのが一般的であるが、上記の溝深さの範囲であればその部分は極僅かであることから、収率低下を小さく抑えられ経済性が高い。更に、ガラス基板と緩衝体との摺擦による発塵量も少なく清浄性の点からも望ましい。
基板挿入溝のピッチはガラス基板等の種類（例えばガラス単体やカラーフィルター、液晶モジュール及び液晶、プラズマディスプレイパネル等）及びそのサイズ、重量、及び緩衝体の圧縮弾性指数、基板挿入溝幅そしてガラス基板の挿入、取り出しの自動化適性等を鑑みて、６ｍｍ以上が好ましく、より好ましくは１００ｍｍ以下がよい。この範囲であると、基板の挿入、取り出しの作業性が容易に且つ確実にできる他、搬送中の振動衝撃や取り扱いでの落下衝撃でガラス基板が撓んで隣りの基板と接触することにより、損傷する危険性も回避できる。
また、本発明の緩衝体において、隣接する基板挿入溝を隔てる凸条の断面形状としては、図４（ａ）に示すように頂部は平面とする。しかし、ガラス基板の挿入作業性や挿入時の発塵を考慮すると、山形（図４（ｂ））や台形（図４（ｃ））のように凸条の上部に案内部を形成した二段形状が好ましく、より好ましくは台形がよい。台形は収納溝ピッチが狭い緩衝体でも型内成形に使用する金型が精度高く製作することができる。また、図中のｔ１は緩衝体１の最大厚み、ｔ２は基板挿入溝２の深さ、ｔ３は溝幅、ｔ４は溝ピッチである。
次に、本発明の緩衝体の構成素材について説明する。
本発明の緩衝体はポリオレフィンビーズ発泡体からなる。当該発泡体は、発泡ポリオレフィンビーズを所望形状の金型内に充填した後、水蒸気で加熱、発泡し、冷却して所望の形状に成形したものである。当該成形に用いる金型としては、鋳物法で得られたものを用いることができる。鋳物法による金型は複雑な形状でも容易に精度高く製作することができ、しかも射出成形用金型に比べ製作費が１／１０以下と廉価であるため、経済的であり、大量生産に適したものである。
本発明に用いられるポリオレフィンビーズ発泡体の成形に用いられるポリオレフィンは架橋型、無架橋型のいずれでも良く、樹脂素材として具体的には、低、中、高密度ポリエチレン、線状低密度ポリエチレン、線状超低密度ポリエチレン、メタロセン触媒のポリエチレン、エチレン−酢酸ビニル共重合体等で代表されるポリエチレン系樹脂や、エチレン、ブテン−１、４−メチルペンテン−１等の共重合成分とプロピレンとのランダム及びブロック共重合ポリプロピレン系樹脂、更にメタロセン触媒を用いて得られた上記ランダム共重合ポリプロピレン系樹脂、及び上記２種以上が配合された組成物が挙げられる。
中でも、ポリエチレン樹脂で、樹脂密度が０．９２７ｇ／ｃｍ^３以上が好ましく、より好ましくは０．９７０ｇ／ｃｍ^３以下のものや、エチレンやブテン−１とプロピレンとのランダム共重合ポリプロピレン系樹脂が好ましい例として挙げられる。ポリエチレン樹脂密度が上記範囲であると、緩衝体は適度の剛性や柔軟性及び回復性等の特性を兼備し、ガラス基板搬送用の緩衝体として充分な実用性能、例えば形状安定性や落下時の衝撃緩衝性能、繰り返し使用耐久性そして耐発塵性が非常によくなる。また、特定の圧縮弾性指数を得るのに緩衝体の発泡倍率を比較的高めることができ、軽量性、経済性の点からも優れる。また、エチレンやブテン−１とプロピレンとのランダム共重合ポリプロピレン系樹脂はポリエチレン樹脂より弾性が高いことから、大きなサイズのガラス基板の緩衝体に適し、特に緩衝体の形状安定性は、長期の繰り返し使用でも初期の状態を維持でき耐久性が優れるので好適である。
本発明のポリオレフィンビーズ発泡体からなる緩衝体は第１に該緩衝体を構成する発泡粒子の平均粒子径が１．５ｍｍ以上が好ましく、より好ましくは５．０ｍｍ以下がよい。更に２．０ｍｍ以上がより好ましく、最も好ましくは４．５ｍｍ以下がよい。平均粒子径がこの範囲であると、発泡粒子１個の体積当たりの表面積比率が小さいので、型内成形において水蒸気加熱時に粒子内のガス圧（空気）が逸散減少する割合が極めて僅かであることから、充分な加熱発泡膨張性が発現する。その結果、得られる型内成形体表面の発泡粒子間には微小な空隙が殆ど発生せず、ガラス基板の搬送用緩衝体として用いた場合に、この部分に空気中の塵埃が浸入せず清浄性に優れたものとなる。また、金型への発泡粒子充填においても狭い幅の基板挿入溝の細部まで発泡粒子を充填することができるので、金型の形状や寸法に沿った高精度の緩衝体が得られる効果がある。
尚、上記発泡粒子の平均粒子径とは、型内成形体の表面に長さが１００ｍｍの直線をボールペンにて３本標示し、この直線上に接している発泡粒子の数を計測して、下記式（Ａ）より平均粒子径Ｃ〔ｍｍ〕を算出する。尚、評価は３本の直線で評価した平均値とする。
Ｃ＝（１．６２６×Ｌ）／Ｎ　　　…（Ａ）
Ｌ：中心線長さ〔ｍｍ〕、Ｎ：粒子数
本発明のポリオレフィンビーズ発泡体からなる緩衝体の第２の要件は該緩衝体の特性にある。即ち、融着率が７０％以上、圧縮弾性指数が３．９以上（より好ましくは４９０以下）、更に回復率が６０％以上であることが好ましい。
尚、上記融着率とは、緩衝体の厚さ方向に深さが約１ｍｍの切れ目を入れ、その切れ目を外側にして折り曲げ破断した際の、破断面における厚さ方向の全長と約７５ｍｍの長さに亘った面積における全発泡粒子個数と粒子破壊（材料破壊）している発泡粒子の個数を測定し、粒子破壊個数を全発泡粒子個数で除した値を百分率で示した数値である。本発明において、かかる融着率が７０％以上であると、本来ポリオレフィンビーズ発泡体が具備する圧縮や引張等の機械的強度に関する固有物性が充分に発現するものとなる。即ち緩衝体を構成する無数の発泡粒子相互が強固に融着一体化しているために耐久性や回復性にも優れ、本緩衝体を用いてガラス基板を固定、包装する場合、固定具の強い締結力にも充分に耐え得るので、ガラス基板を高いレベルで固定、包装ができ、ガラス基板が損傷する確率もより一層低くなる。更に緩衝体表面の発泡粒子間には微小な空隙が存在しなく、繰り返し使用毎に行われる水洗洗浄においても吸水性が実質ゼロであることから乾燥作業性に優れると云った効果もある。
また、本発明において緩衝体の圧縮弾性指数が上記範囲であると、本来ポリオレフィンが有している優れた緩衝性能を効率よく最大限に発揮でき、然も適度の剛性と柔軟性をバランスよく兼備し、特に、ガラス基板寸法が５００ｍｍ×６００ｍｍを超える大型基板でも固定安定性しいては保護機能が非常に高度なものとなる。また、搬送や取り扱い時に係る外力にも充分に絶えられる強度があるために変形が僅かで、長期間に渡って繰り返し使用が可能な耐久性を有する。また、特定の圧縮弾性指数を得るのに緩衝体の発泡倍率を比較的高めることができ、軽量性、経済性の面からも優れる。
さらに、圧縮弾性指数が上記範囲内であって、且つ回復率が６０％以上であるので、ポリオレフィンビーズ発泡体の最大特徴とされる繰り返し耐久性が優れ、使用頻度が高くなっても変形を小さく抑えることができる。
尚、上記圧縮弾性指数とは、圧縮弾性率（Ｎ／ｃｍ^２）を発泡倍率で除した値とする。
上記圧縮弾性率とは、下記発泡倍率を測定した試料について、ＪＩＳ　Ｋ７２２０に準拠して求めた値であり、圧縮速度は１０ｍｍ／分とする。また、試料厚さが２０ｍｍ未満の場合は、約２０ｍｍとなるように複数枚重ねて測定する。
発泡倍率は、緩衝体より、幅５０ｍｍ、長さが５０ｍｍ、厚みが２０ｍｍの平坦な試験片を切り出し、重量（ｇ）を１０ｍｇまで測定した後、ノギスで幅、長さ、厚みを測定し、体積（ｃｍ^３）を算出し、次式（Ｂ）より発泡倍率Ｅ〔ｃｍ^３／ｇ〕を算出する。
Ｅ＝体積／重量〔ｃｍ^３／ｇ〕　　　…（Ｂ）
前記回復率とは、緩衝体より、幅５０ｍｍ、長さが５０ｍｍ、厚みが２０ｍｍの平坦な試験片を切り出し、島津製作所社製の圧縮試験装置「オートグラフＡＧ−５０００Ｄ」を用いて、１０ｍｍ／分の圧縮速度で試験片の厚さの５０％まで圧縮した後、直ちに同速度で荷重がゼロになるまで取り除き、荷重がゼロになった瞬間の厚さを測定し、次式（Ｃ）より回復率Ｒ〔％〕を算出する。尚、厚さが２０ｍｍ未満の場合には、約２０ｍｍとなるように複数枚重ねて測定する。
Ｒ＝（Ｔ１／Ｔ０）×１００〔％〕　　　…（Ｃ）
Ｔ０：試験前厚さ〔ｍｍ〕、Ｔ１：試験後厚さ（荷重がゼロの時）〔ｍｍ〕
次に、本発明の包装体について説明する。本発明の包装体は、上記した本発明の緩衝体を２個以上を一組として、好ましくは４個一組で複数枚のガラス基板を梱包する。即ち、複数枚のガラス基板を所定の間隔をもって平行配置して直方体を形成し、各基板の角部をそれぞれ本発明の緩衝体の基板挿入溝に挿入して該基板表面に対して直交する上記直方体の４辺を上記緩衝体により嵌合する。その後、緩衝体のＬ字に沿って長尺の固定具を巻回して締結する。緩衝体が固定具案内溝を備えている場合には、該固定具案内溝に沿って固定具を巻回する。
尚、最も外側のガラス基板としてはダミーのガラス基板を配置しても良い。
又、本発明の緩衝体を用いた上記ガラス基板包装体以外の実施態様を以下に説明する。
上記と同様にして、複数枚のガラス基板を所定の間隔をもって平行配置して直方体を形成し、各基板の角部をそれぞれ本発明の緩衝体の基板挿入溝に挿入して該基板表面に対して直交する上記長方体の４辺を上記緩衝体により嵌合する。その後、緩衝体のＬ字に沿って長尺の固定具を固定具案内溝に沿って巻回、締結して固定し、梱包体を形成した後、上記梱包体を熱収縮性樹脂フィルムで包装し、加熱処理を施して該フィルムを熱収縮させシュリンク包装する。
尚、必要に応じて上記熱収縮性樹脂フィルムで梱包体を包装する際、袋状或いは筒状に形成したフィルムに梱包体を収納した後、望ましくはフィルムの端部をヒートシールして密封し、該フィルムを熱収縮させて梱包体に密着させてもよい。
上記した包装体は、本発明の緩衝体を用いて複数枚のガラス基板を一体に梱包した梱包体を、熱収縮性樹脂フィルムを用いてシュリンク包装することに特徴を有し、これにより、大型のガラス基板の包装体であっても、梱包体の包装作業が容易になり、自動包装が可能となる。また、包装後の包装体においては熱収縮したフィルムに緩みが全くないために、梱包体の最も外側の基板に該フィルムが接触しガラス基板が汚染されることが皆無であることから、ダミー基板を用いる必要が無く、緩衝体を有効に利用でき効率がよい。さらに、フィルムの収縮応力によって、緩衝体全体が外側から押圧されるため、緩衝体とガラス基板が良好に一体固定化されているので、ガラス基板の溝外れや損傷が無く、また、搬送時の振動によるガラス基板と緩衝体との摺擦が激減し、ガラス基板の傷発生や粉塵付着が防げガラス基板の清浄性が保たれる。
シュリンク包装に用いられる熱収縮性樹脂フィルムとしては、ポリオレフィン系樹脂フィルムやポリ塩化ビニル系樹脂フィルム等があるが、ポリ塩化ビニル系樹脂はその特性から押出成膜時の加工性及び柔軟性を付与するために多量の可塑剤や安定剤等が多種類添加されている。これらの添加剤は成膜後に経時的にフィルム等の表面に滲出したり、或いは、常温下でも極微量の揮発現象があるために、ガラス基板を包装する作業場のクリーン度を悪化させたり、また、ガラス基板の包装取り扱い時に手に付着した添加剤がガラス基板に間接接触する等の致命的な汚染上の問題を発生させる恐れがある。また、搬送中、外部からの塵埃の侵入防止のためには、当該フィルムをヒートシールして、梱包体を密封包装することが望ましいが、ポリ塩化ビニル系樹脂はヒートシール適性が悪く、超音波や高周波シール装置等の高価な装置を必要とするため、ポリオレフィン系樹脂フィルムを用いることが好ましい。
ポリオレフィン系樹脂フィルムとしては、ポリプロピレン系樹脂やポリエチレン系樹脂の単層或いは複層品、また、架橋型或いは無架橋型のいずれでも好ましく用いられる。
係るポリオレフィン系樹脂フィルムは、好ましくは、１２０℃における熱収縮率が縦、横方向の少なくとも一方において１５％以上が好ましく、より好ましくは９０％以下がよい。最も好ましくは２０％以上がよい。さらに望ましくは、縦、横方向共に１５％以上、９０％以下である。当該範囲で熱収縮させると包装体はゆるみなく、タイトにシュリンク包装され、ガラス基板と該フィルムが接触してガラス基板が汚染される恐れがない。尚、かかる熱収縮率は、ＡＳＴＭ　Ｄ−２７３２の方法で１２０℃で測定した値である。
また、１２０℃における最大熱収縮応力が縦、横方向の少なくとも一方において０．１５Ｎ／ｍｍ^２以上が好ましく、より好ましくは５Ｎ／ｍｍ^２以下がよい。最も好ましくは０．２Ｎ／ｍｍ^２以上、４．５Ｎ／ｍｍ^２以下である。さらに望ましくは、縦、横方向共に０．１５Ｎ／ｍｍ^２以上、５Ｎ／ｍｍ^２以下である。
１２０℃における最大熱収縮応力が上記の範囲であると、包装体はゆるみなく、タイトにシュリンク包装され、取り扱い時にフィルムが押圧されても該フィルムがガラス基板と容易に接触せずガラス基板の清浄性が保たれる。また、熱収縮応力が適度であるため、包装時に角部で該フィルムが破れず密封包装ができ、外部からの塵埃侵入が遮断できる。
尚、かかる最大熱収縮応力は、ＡＳＴＭ　Ｄ−２８３８で１２０℃において測定した値である。
さらに、ポリオレフィン系樹脂フィルムの厚みは１０μｍ以上が好ましく、より好ましくは２００μｍ以下がよい。さらにより好ましくは２０μｍ以上、最も好ましくは１８０μｍ以下がよい。当該厚みがこの範囲であると、フィルムは適度な腰を有しているために、梱包体の包装作業性が手際良く容易に効率よくできる。また、溶着強度が高いヒートシールが可能となる他、搬送や取り扱い時の衝撃に耐える破壊強度を有する。
本発明で用いられる固定具としては、紐状、テープ状の長尺のものであれば良く、例えばポリプロピレン製テープが好ましく用いられる。
また、本発明の緩衝体は４個一組で用いられるが、該４個は全く同一であっても、互いに異なる構成であっても良く、例えば大型のガラス基板を梱包する場合には、下方に位置する緩衝体を大きく、厚くしてガラス基板の重量に耐えるものとしても良い。
尚、本発明の緩衝体は上記４個一組で用いる以外に例えば、上部が開口しているプラスチックコンテナーやプラスチック段ボール箱等の内部の底に本発明の緩衝体が移動しないように止め具などを用いて相対する方向に２個固定し、上方開口部からガラス基板を挿入固定するものであり、必要に応じて上部開口部から塵埃が侵入しないように箱体で蓋をすればよく、ガラス基板の保管用として用いることもできる。この場合にガラス蓋体に本発明の緩衝体や板状のプラスチック発泡体を取りつけることで搬送用容器としても使用できる。
＜実施例＞
（実施例１、参考実施例１）
〔ガラス基板〕
液晶ディスプレイ用マザーガラス
寸法：６００ｍｍ×７２０ｍｍ
厚み：０．７ｍｍ
〔発泡体〕
樹脂素材：発泡倍率が２０ｃｍ^３／ｇのエチレン・プロピレンランダム共重合体
樹脂発泡粒子の平均粒子径：３．６ｍｍ
融着率：８６％
圧縮弾性率：５４９Ｎ／ｃｍ^２
圧縮弾性指数：２７．５
〔緩衝体〕
ガラス基板収納枚数：２６枚
外形寸法；
短辺：２５０ｍｍ
長辺：３５０ｍｍ
長さ（短辺、長辺に直交する長さ）：３００ｍｍ
最大厚さ：３２ｍｍ
基板挿入溝；
幅：２．４ｍｍ
深さ：１２ｍｍ
ピッチ：２０ｍｍ
凸条の断面形状：基板挿入溝の底面より垂直に６．５ｍｍの壁面を有し、頂部は平面部分の幅が８ｍｍで高さが５．５ｍｍの台形（図４（ｃ）の形状）
〔固定具案内溝〕
両側部より上記緩衝体の長さ（３００ｍｍ）の１／４の位置に幅３０ｍｍで合計２本設けた。溝の深さはＬ字の端部で１ｍｍとし、角部には半径２０ｍｍの円弧状の面取り部を形成し、溝の底部と面取り部との接続部における溝の深さを４ｍｍとした。
〔自由落下試験〕
上記ガラス基板を、上記緩衝体を４個用いて図２に示すように包装し、包装体とした。この包装体における上記緩衝体の緩衝性能を評価するために、自由落下試験を実施した。尚、参考実施例１として、融着率が６５％である以外は全く同じ緩衝体を用いて同様の試験を行った。
試験条件
落下高さ：３０ｃｍ
包装体落下面：包装体の地のみ
落下回数：３回
実施例１の包装体は、３回落下後もガラス基板の脱落が全くなく、試験前のガラス基板梱包状態を維持しており、ガラス基板の損傷も見られなかった。また、ガラス基板表面への緩衝体粉塵の付着は、目視で観察できる大きさの粉塵は全く見られなかった。
参考実施例１の包装体は、ガラス基板の脱落はなかったものの、地に配した緩衝体の長辺方向の溝部に接触していたガラス基板の端部に微小な欠けが発生していた。この欠けの発生の原因を究明するべく、当該緩衝体を詳細に観察した結果、発泡ビーズ間に亀裂が発生しており、落下衝撃でガラス基板が緩衝体に食い込んだためであると考えられる。また、発泡ビーズが脱落した形跡も認められ、繰り返し使用に耐える耐久性が実施例１の緩衝体に比べて劣っていることがわかった。即ち、緩衝体の融着率が７０％未満であったため、緩衝体が本来有する機械的強度に劣り、落下衝撃を受けた際に過度の歪みが生じたためと考えられる。
（実施例２、比較例１）
〔ガラス基板〕
液晶ディスプレイ用マザーガラス
寸法：５５０ｍｍ×６５０ｍｍ
厚み：０．７ｍｍ
〔発泡体〕
樹脂素材：発泡倍率が１０ｃｍ^３／ｇで樹脂密度が０．９３０ｇ／ｃｍ^３の架橋型ポリエチレン
発泡粒子の平均粒子径：２．８ｍｍ
融着率：９８％
圧縮弾性率：４１２Ｎ／ｃｍ^２
圧縮弾性指数：４１．２
〔緩衝体〕
ガラス基板収納枚数：１２枚
外形寸法；
短辺：２１０ｍｍ
長辺：３１０ｍｍ
長さ（短辺、長辺に直交する長さ）：２４０ｍｍ
最大厚さ：２３ｍｍ
基板挿入溝；
幅：１．５ｍｍ
深さ：７ｍｍ
ピッチ：２０ｍｍ
凸条の断面形状：基板挿入溝の底面より垂直に３．５ｍｍの壁面を有し、頂部は高さが３．５ｍｍの山形（図４（ｂ）の形状）
〔固定具案内溝〕
両側部より上記緩衝体の長さ（２４０ｍｍ）の１／４の位置に幅２５ｍｍで合計２本設けた。Ｌ字の端部から角部に向かって５０ｍｍの位置から角部に向けて溝を形成し、角部には半径１０ｍｍの円弧状の面取り部を形成し、溝の底部と面取り部との接続部における溝の深さを３ｍｍとした。
〔振動試験〕
上記ガラス基板を、上記緩衝体を４個用いて図２に示すように包装し、包装体とした。この包装体における上記緩衝体のガラス基板梱包固定性能を評価するために、振動試験を実施した。振動試験は該包装体を振動試験装置の加振テーブルに固定し、ＪＩＳ　Ｚ０２３２の試験方法に準拠して行った。また、比較例１として、固定具案内溝の深さを全ての部位で１ｍｍとした以外は、全く同じ緩衝体を用いて同様の試験を行った。
試験条件
振動方向：上下
振動波形：正弦波
掃引：対数掃引（周波数５〜１００Ｈｚ）
掃引速度０．５オクターブ／分
振動加速度：±０．７５Ｇ
振動時間：３０分
振動試験終了後にガラス基板の梱包固定状態を目視で観察したところ、実施例２の包装体は、ガラス基板にわずかに緩みが見られるものの、基板挿入溝から脱落したガラス基板は１枚もなかった。また、ガラス基板表面への緩衝体粉塵の付着は、目視で観察できる大きさの粉塵は全く見られなかった。
比較例１の包装体は、振動試験開始後８分で、上部２個の緩衝体の長辺の基板挿入溝においてガラス基板の脱落が発生し、隣のガラス基板と接触したために破損の危険があることから、試験を中止した。
本発明を詳細にまた特定の実施態様を参照して説明したが、本発明の精神と範囲を逸脱することなく様々な変更や修正を加えることができることは当業者にとって明らかである。
本出願は、２０００年１２月２７日出願の日本特許出願（特願２０００−３９６９３４）に基づくものであり、その内容はここに参照として取り込まれる。
＜産業上の利用可能性＞
以上説明したように、本発明の緩衝体は固定具で締結した際に、固定具の締結力の角部への集中が防止されるため、端部においてもガラス基板を良好に押圧してガラス基板の溝はずれがなく、良好な保護効果を発現する。特に本発明の緩衝体はその寸法を調整し、構成素材である発泡体として特定の特性を備えたものを用いることにより、ガラス基板の梱包、取り外し作業が容易になり、自動化にも適したものとなる。また、発塵性や耐久性にも優れ、クリーンルーム内での作業に適応し、繰り返し多数回使用にも耐えるものである。よって、本発明の緩衝体を用いて複数のガラス基板を梱包した本発明の包装体においては、搬送時の振動衝撃や落下衝撃に対しても内部のガラス基板が確実に保護され、不良品の発生が大幅に抑えられる。
【図面の簡単な説明】
図１は、本発明の緩衝体の一実施形態の斜視図である。
図２は、本発明の包装体の一実施形態の斜視図である。
図３（ａ）乃至３（ｅ）は、本発明の緩衝体の実施形態の断面模式図である。
図４（ａ）乃至４（ｃ）は、本発明の緩衝体の基板挿入溝の構成例を示す断面模式図である。
なお、図中の符号、１は緩衝体、２は基板挿入溝、３は固定具案内溝、４は凸条、２１はガラス基板、２２は固定具、３１は緩衝体の壁面、３２は基板挿入溝の底部、３３はＬ字の端部、３４，３４’はＬ字の角部、３５は固定具案内溝の底部、３６は面取り部、３７は切り欠き溝、３８は凸部、３９は凹部である。<Technical field>
The present invention provides a transfer buffer for protecting a glass substrate having electronic components such as a semiconductor device formed on a glass substrate from damage due to vibration during transportation, and a plurality of the glass substrates using the buffer. The present invention relates to a package packaged simultaneously.
<Background technology>
In recent years, the production volume of electronic and electrical related devices, especially liquid crystal displays and plasma displays, which are one of the peripheral devices of personal computers, and mobile terminals typified by mobile phones, has been increasing with the development of the information technology industry typified by the Internet. It is a device that is growing at a rapid pace, and there is a strong demand for the development of buffer-related technology used for packaging and transporting the device. Among them, a glass substrate incorporating electronic components such as a semiconductor device, for example, a color filter, a TFT liquid crystal cell (a substrate on which a circuit incorporating a thin film transistor is formed), and a glass substrate used for a liquid crystal panel have a small thickness. In addition, they are susceptible to shocks and vibrations during transportation, and because of their very fine structure, are susceptible to external influences and are difficult to handle. In particular, when transporting a glass substrate before processing or a semi-finished product before becoming a final product, the above electronic components are handled in a bare state, so they are more strongly affected by static electricity, dust, dust, etc. In some cases, the function was impaired.
Therefore, many packaging techniques have been proposed for safely transporting the glass substrate without damaging it.
As an example, there is a technique disclosed in Japanese Patent Application Laid-Open No. 5-319456. The key point is a buffer made of a polyolefin bead foam having specific characteristics and having a substantially L-shaped cross section and a plurality of substrate insertion grooves provided inside along the L-shape. In packing the glass substrates, a plurality of glass substrates are arranged in parallel at a predetermined interval to form a rectangular parallelepiped, and the corners of each substrate are respectively inserted into the substrate insertion grooves of the buffer, and are orthogonal to the substrate surface. The four sides of the rectangular parallelepiped to be formed are fitted by the buffer, and further fixed with a fixing tool such as rubber or tape as necessary.
However, when the fixing member such as rubber or tape is fixed to the outside of the shock absorber, the fastening force is concentrated on the corner portion of the shock absorber, so that the L-shape is opened and the glass base is covered at both ends. In some cases, the protection function may not work sufficiently due to a deviation from the substrate insertion groove.
Further, the above-mentioned L-shaped buffer has a groove width of the substrate insertion groove formed to be equal to or slightly smaller than the thickness of the glass substrate, and has a high elastic recovery property during compression which is a characteristic of the polyolefin bead foam. Is used to fix the glass substrate. Therefore, it is effective for dust resistance due to vibration friction with the glass substrate during transportation, but when packing the glass substrate, which is the original purpose, the frictional resistance with the glass substrate has an adverse effect, and it is impossible. When trying to fit the glass substrate into the substrate insertion groove, the extremely thin glass substrate of about 0.4 to 1.0 mm is easily bent and easily broken, and it takes a long time to work carefully to avoid damage The problem has arisen. This is the same when taking out the glass substrate. In particular, recently, automatic storage and removal devices for glass substrates have been introduced from the viewpoint of labor saving, but it has been pointed out that problems are liable to occur due to the above problems, and that they are not suitable for automation as a real problem.
Further, when the glass substrate is inserted into the substrate insertion groove, fine scratches may occur on the surface of the glass substrate due to frictional resistance, which is a problem.
In view of the above problems, the problem of the present invention is that the glass substrate groove at the L-shaped end of the buffer does not slip when packing the glass substrate, and the glass is not subjected to external force such as vibration or drop impact during transportation or handling. It is an object of the present invention to provide a buffer for a glass substrate that can safely protect a substrate, and further, is suitable for automation of storage and removal of the glass substrate, and does not easily generate dust even when rubbed with the glass substrate. Another object of the present invention is to provide a buffer for a glass substrate which is excellent in durability and can be used a plurality of times, and to provide a package packed by using the buffer.
<Disclosure of the Invention>
The first glass substrate buffer of the present invention is a glass substrate buffer made of a foamed polyolefin bead, and has a substantially L-shaped cross section according to the shape of the corner of the glass substrate. The inside surface is provided with a plurality of substrate insertion grooves for fixing the two sides forming the corners of the glass substrate, and the outside surface is provided with at least one fixture guide formed along the L-shape. The buffer has a groove, and the thickness of the buffer body with respect to the bottom of the fixture guide groove is gradually reduced from both ends of the L-shape toward the corners.
The first buffer member for a glass substrate of the present invention preferably includes that the bottom of the fixing tool guide groove at the corner is chamfered.
The second buffer for a glass substrate of the present invention is a buffer for a glass substrate made of a foamed polyolefin bead, and has a substantially L-shaped cross-section according to the shape of the corner of the glass substrate, and is formed along the L-shape. The inside surface is provided with a plurality of substrate insertion grooves for fixing the two sides forming the corners of the glass substrate, and the thickness of the buffer gradually decreases from both ends of the L-shape toward the corners. Is what it is.
The third glass substrate buffer of the present invention is a glass substrate buffer made of a polyolefin bead foam, and has a substantially L-shaped cross section according to the shape of the corner of the glass substrate, and extends along the L-shape. On the inner surface, a plurality of substrate insertion grooves for fixing the two ends forming the corners of the glass substrate are provided, and convex portions are formed at both outer ends of the L-shape.
The second and third buffer members for a glass substrate of the present invention preferably include that the outer corners are chamfered.
Further, the buffer for a glass substrate of the present invention has a cutout groove on the inner side in a direction orthogonal to the substrate insertion groove, the maximum thickness of the buffer is 10 to 60 mm, and the ratio of the two sides of the L-shape is short. The side width is 1.0 to 3.0, the groove width of the substrate insertion groove is 1.0 to 4.0 times the thickness of the glass substrate, the groove depth is 3 to 15 mm, and the groove pitch is 6 to 100 mm. That the polyolefin bead foam has an average particle diameter of the expanded particles of 1.5 to 5.0 mm, a fusion rate of 70% or more, a compression elasticity index of 3.9 to 490, and a recovery rate of 60% or more. Is included as a preferred embodiment.
Further, the first package of the present invention forms a rectangular parallelepiped by arranging a plurality of glass substrates in parallel at a predetermined interval, and forms the corners of each substrate in the first glass substrate buffer of the present invention. Four sides of the rectangular parallelepiped which is inserted into the insertion groove and orthogonal to the substrate surface are fitted by the buffer, and a long fixing tool is wound and fastened along the fixing tool guide groove of the buffer. It is characterized by the following.
Further, the second package of the present invention forms a rectangular parallelepiped by arranging a plurality of glass substrates in parallel at a predetermined interval, and forms the corners of each substrate in the second or third glass substrate buffer of the present invention, respectively. The four sides of the rectangular parallelepiped orthogonal to the substrate surface are inserted into the substrate insertion groove by the buffer, and a long fixture is wound around the outside of the buffer along the L-shape. It is characterized by having been concluded.
<Best mode for carrying out the invention>
The shock absorber of the present invention is characterized in that in the shock absorber having a substantially L-shaped cross section made of a polyolefin bead foam, the end of the L-shape is formed to be thicker than the corners. When the glass substrate is packed and the outside is fastened by a fixture, the fixture passes through the outside of the corner at the end of the L-shape, and the fastening force of the fixture concentrates on the corner. In this case, the glass substrate can be protected by pressing the entire buffer evenly.
In the present invention, a specific configuration for making the thickness of the L-shaped end portion of the buffer body larger than the corner portion is as follows.
(1) By forming the depth of the fixture guide groove so as to increase from the end of the L-shape toward the corner, the thickness of the buffer at the bottom of the fixture guide groove is reduced to the end of the L-shape. From the to the corner.
(2) The buffer is formed such that the thickness of the buffer itself decreases gradually from both ends of the L-shape toward the corners without forming the fixing tool guide groove.
(3) Protrusions are formed at both ends outside the L-shape of the buffer.
Hereinafter, the buffer of the present invention and a package in which a plurality of glass substrates are integrally packaged using the buffer will be specifically described with reference to embodiments.
FIG. 1 is a perspective view of one embodiment of the shock absorber of the present invention having the configuration (1). In the drawing, reference numeral 1 denotes a buffer, 2 denotes a substrate insertion groove, 3 denotes a fixture guide groove, and 4 denotes a ridge separating the adjacent substrate insertion grooves 2. FIG. 2 is a perspective view of an embodiment of the package of the present invention in which a plurality of glass substrates are packed using four of the buffers. In the figure, 21 is a glass substrate, 22 is a fixture, and the same members as those in FIG.
Although the buffer 1 of the present invention protects the corners of the glass substrate 21 and fixes a plurality of the substrates integrally, the packaging is performed in groups of two or more, preferably four.
As shown in FIG. 1, the buffer 1 of the present invention has a substantially L-shaped cross section according to the shape of the corner of the glass substrate, and the L-shape is used to fix two ends forming the corner of the glass substrate. A plurality of substrate insertion grooves 2 are provided along and separated from each other by ridges 4.
In the case where the configuration (1) is provided, the fixture guide groove 3 is formed along the L-shape. As shown in FIG. 2, the fixture guide groove 3 is for winding the fixture 22 along the guide groove 3 after packing the glass substrate 21. In the present invention, the fixture guide groove 3 is used. Is provided, the depth is changed so that the thickness of the buffer 1 at the bottom gradually decreases toward the corner. FIG. 3A schematically shows a cross section along the fixture guide groove 3 and the substrate insertion groove 2 of the buffer 1 of FIG. 3, reference numeral 31 denotes an outer wall surface of the buffer 1, 32 denotes a bottom surface of the substrate insertion groove 2, 33 denotes an L-shaped end of the buffer 1, 34 and 34 'denote L-shaped corners, and 35 denotes a fixture guide. The bottom of the groove 3, 36 is a chamfered portion, 37 is a cutout groove, 38 is a convex portion, and 39 is a concave portion. In the following description, the thickness at the corner 34 or 34 'refers to the thickness of the short side and the long side of the buffer at the inner corner of the L-shape.
As shown in FIG. 3A, the depth of the fixture guide groove is formed so as to be shallow at the L-shaped end 33 and deep at the corner 34 'so that the bottom of the fixture guide groove is formed. The thickness of the buffer at 35 gradually decreases from the L-shaped end 33 toward the corner 34 '. As a result, when the long fixture is wound along the fixture guide groove after packing the glass substrate, the distance from the fixture to the glass substrate is larger at the end 33 than at the corner 34 ′, It is possible to prevent the fastening force of the fixing tool from being concentrated on the corner 34 '.
Further, in order to prevent the fastening force of the fixing tool from concentrating on the corner 34 'of the bottom 35 of the fixing tool guide groove, as shown in FIG. It is also preferable to keep it. By forming the chamfered portion 36, there is no possibility that the fixing tool will bite into the buffer and cause damage, the deformation at the corner 34 'is reduced, and the end 33 of the buffer is hard to open outward. The chamfered portion 36 may have a planar shape or a curved shape.
Further, as shown in FIG. 3 (c), a cut is made in the buffer body in a direction perpendicular to the substrate insertion groove (a direction perpendicular to the paper surface), and at least one notch groove 37 is provided, so that the fixture is used. It is preferable that the notch groove 37 absorbs the deformation stress that tends to open the end portion 33 outward at the time of fastening and does not propagate the deformation stress to the end portion 33. It should be noted that the shape of the notch groove 37 may be a substantially U-shape or the like in addition to the substantially V-shape shown in FIG.
In FIG. 3, a concave portion 39 from which the ridges 4 are partially removed is formed inside the corner portion 34 on the short side, which is subjected to a vibration impact or a drop impact during transportation. This is a configuration for preventing the corner of the glass substrate that is most easily damaged in such a case. In the recess 39, the protrusion 4 may be removed until it reaches the bottom 32 of the substrate insertion groove. Further, from the viewpoint of preventing the corners of the glass substrate from being damaged, it is preferable to form the glass substrate further deeper than the bottom 32.
In the present invention, as an example of a configuration in which the L-shaped end 33 of the buffer is thicker than the corner 34, an example of the above-described configuration (2) is shown in FIG. 3D, and an example of the configuration (3) is shown in FIG. e). In FIG. 3D, the thickness of the buffer itself is formed so as to gradually decrease from the L-shaped end 33 toward the corner 34. In this case, since the fixing tool guide groove is not particularly formed, the width and the winding position of the fixing tool can be freely selected. Further, in FIG. 3E, the thickness of the buffer is uniform, but a convex portion 38 is formed outside the L-shaped end 33, and as a result, the thickness of the buffer at the end 33 is square. It is thicker than the part 34. The convex portion 38 may be formed integrally with the main body, but may be separately formed into a plate shape and then attached to the main body by heat fusion or an adhesive, in which case the same material as the main body is used. Or different materials.
In the configurations of FIGS. 3D and 3E, the chamfered portion 36 and the notch 37 as shown in FIGS. 3B and 3C can be appropriately incorporated.
Next, preferred external dimensions of the cushioning body of the present invention will be described.
In the buffer of the present invention, the ratio of the two sides of the L-shape (the length of the portion in contact with the glass substrate) is preferably 1.0 or more, more preferably 3.0 or less, based on the short side. Within this range, the long side and the short side are well-balanced, and the fixing stability of the rectangular glass substrate becomes very good. In addition, the probability that the glass substrate is bent and damaged is lower. More preferably, it is less than 2.7.
Further, within the above range, the length of the short side is preferably at least 10% of the length of the short side of the glass substrate to be packed, more preferably at most 45%. Further, it is preferably at least 15%, and most preferably at most 40%. If the length of the short side of the buffer is within the above range, even if it receives a drop impact, etc., the buffer which sufficiently absorbs the impact force is arranged, so that the risk of damaging the glass substrate is reduced. Can be avoided. In addition, since the stress (self-weight of the glass substrate) on the buffer can be reduced, dust generation due to contact friction due to vibration during transportation is suppressed, and cleanliness can be satisfied.
As a specific external dimension, the short side is preferably 100 mm or more, and more preferably 500 mm or less. The long side is preferably 100 mm or more, more preferably 1500 mm or less. The length in the direction orthogonal to the short side and the long side depends on the number of glass substrates accommodated, but is preferably 150 mm or more, more preferably 600 mm or less.
The maximum thickness of the buffer of the present invention is preferably 10 mm or more, more preferably 60 mm or less, in consideration of the size, weight, number of packages, compression elasticity index and the like of the glass substrate. More preferably, it is 15 mm or more and / or 40 mm or less. When the external dimensions and the maximum thickness are in the above ranges, the glass substrate before processing can be used as a transfer buffer that can stably fix all glass substrate products of various dimensions as well as the glass substrate before processing. In addition, a glass substrate protection function that can sufficiently withstand the impact during transportation can be exhibited.
Further, when the fixture guide groove is formed as shown in FIG. 3A, the depth is preferably 0.5 mm or more at the end 33, more preferably 5 mm or less, and further 2 mm or more at the corner 34 '. Preferably, it is 15 mm or less. If the depth of the fixing tool guide groove is formed so as to fall within this range, the fixing force is not only displaced but also when the fixing tool is fastened and fixed by the fixing tool over the entire short side and long side of the buffer. Since the shock absorbers are prevented from being deformed by the open legs, and the corners of the four glass substrates can be fixed stably, the function of protecting the glass substrates is sufficiently satisfied. In FIG. 3A, the fixture guide groove is formed up to the end 33, but may be formed near the end 33 so as to be flush with the outer wall 31 of the shock absorber. The tool guide groove is preferably separated from the end 33 by 10 mm or more, more preferably from the position 100 mm or less from the end 33 to the corner 34 ′. Within this range, there is no displacement of the fixture during conveyance, and the same effect as when the guide groove is formed from the end 33 can be obtained.
Furthermore, when changing the thickness of the buffer body itself as shown in FIG. 3D, it is preferable that the thickness of the corner portion 34 be thinner than the thickness of the end portion 33 by 1 mm or more, and more preferably 10 mm or less. More preferably, it is 3 mm or more, most preferably 8 mm or less. Also in this case, the end portion 33 is formed in a uniform thickness with the thickness of the end portion 33 up to a position of 10 mm or more, more preferably 100 mm or less in the direction of the corner portion 34 from the end portion 33, and the thickness from the position to the corner portion 34. The same effect as described above can be obtained even if the length is gradually reduced.
Further, in the case of FIG. 3E, it is preferable that the thickness of the corner portion 34 is thinner than the thickness of the end portion 33 by 1 mm or more, and more preferably 10 mm or less. The means for thinning the corner 34 can be achieved by forming a convex 38 near the end 33 as shown in FIG. Further, the width of the projection 38 in the direction along the L-shape is preferably 10 mm or more, and more preferably 100 mm or less. It is more preferably at least 20 mm, most preferably at most 80 mm.
Further, in the case of forming the chamfered portion 36 shown in FIG. 3B, in consideration of the compression elasticity index, the maximum thickness, the length of both sides, and the like of the cushioning member, the L-shaped cross section is formed in an arc shape or a straight line shape. Therefore, the length is preferably 3 mm or more, more preferably 60 mm or less.
When the chamfer is within this range, when the glass substrate is packed and the outside thereof is fastened by the fastener, the fastening force of the fastener is prevented from being concentrated on the corners, so that the entire buffer is pressed evenly. Thus, the corners of the glass substrate can be fixed. Therefore, the function of fixing and protecting the glass substrate is further enhanced, and even when the fixing tool is wound with a strong fastening force, the phenomenon that the fixing tool cuts and bites into the buffer is eliminated, and the glass substrate is reused repeatedly for a long period of time. The durability can be greatly improved.
Further, when the notch groove 37 shown in FIG. 3C is formed, the groove depth is preferably 1/20 or more, more preferably 1/2 of the thickness of the buffer at the portion where the notch groove 37 is formed. The following is good. Further, the groove width is preferably 2 mm or more, more preferably 10 mm or less. Although the position and the number of the notch grooves 37 are not particularly limited, the side length (the length of the portion in contact with the glass substrate) is larger than the corner (the contact point of the short side and the long side with the glass substrate). ) Is preferably 1/8 or more, more preferably 1/5 or more, and more preferably 3/5 or less. When the cutout groove 37 is formed in the above range, the glass substrate insertion groove can be fixed firmly over the entire length of the glass substrate insertion groove without deteriorating the rigidity of the buffer, so that the protection function of the substrate is improved, and Also, the effect of lowering the frictional dust generation of the shock absorber is derived.
Furthermore, when forming the concave portion 39 of FIG. 3, it is preferable to set the bottom of the concave portion 39 to reach the bottom portion 32 of the substrate insertion groove, more preferably the size and thickness of the glass substrate and the maximum thickness of the buffer. In consideration of the above, the depth is preferably 1 mm or more, most preferably 8 mm or less, most preferably 2 mm or more, and most preferably 6 mm or less from the bottom 32 of the substrate insertion groove. In this range, even if the shock absorber is deformed due to a drop impact or the like, no external force is applied to the most fragile corner of the glass substrate, so that the probability of damage is extremely low. In addition, since the structural strength of the buffer can be sufficiently maintained, the initial shape can be maintained even if the buffer is repeatedly used. Therefore, the function of fixing and protecting the glass substrate can be exhibited for a long time.
The groove width of the substrate insertion groove formed in the buffer of the present invention is preferably 1.0 times or more and 4.0 times or less, more preferably 1.2 times or more and 3.5 times or more the thickness of the glass substrate to be packed. Double or less is better. Within this range, the operation of inserting and removing the glass substrate by a manual or automatic device can be performed quickly and efficiently, and the trouble of damage to the glass substrate during the insertion operation is drastically reduced. In addition, since the glass substrate is sufficiently fixed in the substrate insertion groove, friction between the glass substrate and the buffer is suppressed even if it is subjected to vibration or shock during transportation, and the dusting phenomenon is extremely low. I can keep it.
Further, the depth of the substrate insertion groove is preferably 3 mm or more, more preferably 15 mm or less, in consideration of the size and weight of the glass substrate, the compression elasticity index of the buffer, the groove width of the substrate insertion groove, and the like. More preferably, it is 5 mm or more, most preferably 10 mm or less. Within this range, the glass substrate can be securely fixed with the glass substrate inserted in the insertion groove even if it receives a vibration shock during transportation or a drop shock due to handling, so that the glass substrate comes out of the insertion groove and contacts the adjacent substrate Such damage accidents can be prevented. In addition, since the portion where the glass substrate comes into contact with the substrate insertion groove constantly rubs against the buffer due to the vibration and impact during transportation, there is a very high possibility that fine abrasions are generated on the surface of the glass substrate. Therefore, for example, when processing the conveyed glass substrate into a liquid crystal panel or the like, it is common to cut and remove the substrate portion that has been in contact with the substrate insertion groove of the buffer before use, but the above-described groove is generally used. In the range of the depth, the portion is extremely small, so that the reduction in yield can be suppressed to a small value, and the economy is high. Further, the amount of dust generated by the rubbing between the glass substrate and the buffer is small, which is desirable from the viewpoint of cleanliness.
The pitch of the substrate insertion groove is the kind of glass substrate or the like (eg, glass alone, color filter, liquid crystal module and liquid crystal, plasma display panel, etc.), its size, weight, compression elasticity index of the buffer, substrate insertion groove width, and glass substrate. In view of the suitability for the automatic insertion and removal of the paper, it is preferably 6 mm or more, more preferably 100 mm or less. Within this range, the workability of inserting and removing the substrate can be easily and reliably performed, and the glass substrate is bent by a vibration shock during transportation or a drop impact during handling, and is damaged by contact with an adjacent substrate. The danger of doing can be avoided.
Further, in the cushioning body of the present invention, the cross-sectional shape of the ridge separating the adjacent substrate insertion grooves has a flat top as shown in FIG. However, in consideration of the workability of inserting the glass substrate and dust generation at the time of insertion, a two-stage structure in which a guide portion is formed on the upper part of the ridge like a chevron (FIG. 4B) or a trapezoid (FIG. 4C). A shape is preferable, and a trapezoid is more preferable. With a trapezoid, a mold used for in-mold molding can be manufactured with high precision even for a buffer having a narrow storage groove pitch. In the drawing, t1 is the maximum thickness of the buffer 1, t2 is the depth of the substrate insertion groove 2, t3 is the groove width, and t4 is the groove pitch.
Next, the constituent material of the buffer of the present invention will be described.
The buffer of the present invention comprises a polyolefin bead foam. The foam is formed by filling foam polyolefin beads in a mold having a desired shape, heating and foaming with steam, cooling, and then molding the foam into a desired shape. As a mold used for the molding, a mold obtained by a casting method can be used. Molds made by the casting method can be easily manufactured with high precision even for complicated shapes, and the production cost is less than 1/10 that of injection molds, making them economical and suitable for mass production. It is a thing.
The polyolefin used for molding the polyolefin bead foam used in the present invention may be any of a crosslinked type and a non-crosslinked type, and specifically, as a resin material, low, medium, high density polyethylene, linear low density polyethylene, linear Ultra low density polyethylene, polyethylene of metallocene catalyst, polyethylene resin represented by ethylene-vinyl acetate copolymer and the like, and random copolymerization of propylene with a copolymer component such as ethylene, butene-1, 4-methylpentene-1, etc. And a block copolymerized polypropylene resin, a random copolymerized polypropylene resin obtained using a metallocene catalyst, and a composition containing two or more of the above.
Above all, a polyethylene resin having a resin density of 0.927 g / cm³Or more, more preferably 0.970 g / cm³Preferred examples include the following and a random copolymerized polypropylene resin of ethylene or butene-1 with propylene. When the polyethylene resin density is within the above range, the buffer has properties such as moderate rigidity and flexibility and recoverability, and has sufficient practical performance as a buffer for glass substrate transfer, for example, shape stability and dropping when falling. The shock absorbing performance, the durability for repeated use and the dust resistance are very good. In addition, the foaming ratio of the buffer can be relatively increased to obtain a specific compression elasticity index, which is excellent in terms of lightness and economy. In addition, since the random copolymerized polypropylene resin of ethylene or butene-1 and propylene has higher elasticity than the polyethylene resin, it is suitable for a buffer of a large-sized glass substrate. It is preferable because the initial state can be maintained even during use and the durability is excellent.
First, in the buffer comprising the polyolefin bead foam of the present invention, the average particle diameter of the expanded particles constituting the buffer is preferably 1.5 mm or more, more preferably 5.0 mm or less. It is more preferably 2.0 mm or more, and most preferably 4.5 mm or less. When the average particle diameter is in this range, the ratio of the surface area per volume of one expanded particle is small, so that the rate at which the gas pressure (air) in the particle escapes and decreases during steam heating in the in-mold molding is extremely small. Therefore, sufficient heat expansion swelling property is exhibited. As a result, little voids are hardly generated between the foamed particles on the surface of the obtained in-mold molded body, and when used as a buffer for transporting a glass substrate, dust in the air does not penetrate into this portion to clean. It will be excellent in property. In addition, even when filling the foamed particles into the mold, the foamed particles can be filled up to the details of the narrow substrate insertion groove, so that there is an effect that a high-precision cushioning body along the shape and dimensions of the mold can be obtained. .
In addition, the average particle diameter of the foamed particles, three straight lines having a length of 100 mm on the surface of the in-mold molded product are marked with a ballpoint pen, and the number of foamed particles in contact with the straight line is measured. The average particle diameter C [mm] is calculated from the following equation (A). The evaluation is an average value evaluated by three straight lines.
C = (1.626 × L) / N (A)
L: center line length [mm], N: number of particles
A second requirement of the buffer comprising the polyolefin bead foam of the present invention resides in the properties of the buffer. That is, the fusion rate is preferably 70% or more, the compression elasticity index is 3.9 or more (more preferably 490 or less), and the recovery rate is preferably 60% or more.
In addition, the said fusion rate, when a cut having a depth of about 1 mm is made in the thickness direction of the buffer body, and the cut is made to be outside to break and bend, the total length in the thickness direction of the fracture surface and about 75 mm This is a numerical value obtained by measuring the total number of foamed particles and the number of foamed particles that have undergone particle destruction (material destruction) in the area over the length, and dividing the number of broken particles by the total number of foamed particles as a percentage. In the present invention, when the fusion rate is 70% or more, the intrinsic properties of the polyolefin bead foam inherently related to mechanical strength such as compression and tension are sufficiently exhibited. That is, since the innumerable foam particles constituting the buffer are firmly fused and integrated with each other, they are excellent in durability and recoverability, and when the glass substrate is fixed and packaged using the present buffer, a strong fixing tool is used. Since it can sufficiently withstand the fastening force, the glass substrate can be fixed and packaged at a high level, and the probability of damaging the glass substrate is further reduced. Furthermore, there is also an effect that there is no fine void between the foamed particles on the surface of the buffer body and that the water absorption is substantially zero even in the washing and washing performed repeatedly, so that the drying workability is excellent.
Further, in the present invention, when the compression elasticity index of the shock absorber is in the above range, the excellent shock-absorbing performance inherent in polyolefin can be efficiently exhibited to the maximum, and a proper rigidity and flexibility are well-balanced. In particular, even for a large-sized substrate having a glass substrate size exceeding 500 mm × 600 mm, the protection function is extremely advanced if the fixing stability is secured. In addition, since there is sufficient strength to withstand external forces during transportation and handling, there is little deformation, and there is durability that enables repeated use for a long period of time. In addition, the foaming ratio of the buffer can be relatively increased to obtain a specific compression elasticity index, which is excellent in terms of lightness and economy.
Further, since the compression elasticity index is within the above range and the recovery rate is 60% or more, the polyolefin bead foam has excellent repetition durability, which is the largest feature, and has a small deformation even when used frequently. Can be suppressed.
In addition, the said compression elasticity index is a compression elastic modulus (N / cm²) Is divided by the expansion ratio.
The compression elastic modulus is a value obtained in accordance with JIS K7220 for a sample for which the following expansion ratio is measured, and the compression speed is 10 mm / min. In addition, when the sample thickness is less than 20 mm, the measurement is performed by stacking a plurality of samples so that the thickness becomes about 20 mm.
The foaming ratio was determined by cutting out a flat test piece having a width of 50 mm, a length of 50 mm, and a thickness of 20 mm from the buffer, measuring the weight (g) to 10 mg, and measuring the width, length, and thickness with a caliper. Volume (cm³) Is calculated, and the expansion ratio E [cm] is calculated from the following equation (B).³/ G] is calculated.
E = volume / weight [cm³/ G] ... (B)
The recovery rate was determined by cutting a flat test piece having a width of 50 mm, a length of 50 mm, and a thickness of 20 mm from the buffer, and using a compression tester “Autograph AG-5000D” manufactured by Shimadzu Corporation at 10 mm / After compressing to 50% of the thickness of the test piece at a compression speed of 1 minute, remove it immediately at the same speed until the load becomes zero, measure the thickness at the moment when the load becomes zero, and use the following formula (C). The recovery rate R [%] is calculated. In addition, when the thickness is less than 20 mm, a plurality of sheets are measured so as to be about 20 mm.
R = (T1 / T0) × 100 [%] (C)
T0: Thickness before test [mm], T1: Thickness after test (when load is zero) [mm]
Next, the package of the present invention will be described. The packaging body of the present invention packs a plurality of glass substrates in a set of two or more of the above-described buffer bodies of the present invention, and preferably in a set of four. That is, a plurality of glass substrates are arranged in parallel at predetermined intervals to form a rectangular parallelepiped, and the corners of each substrate are inserted into the substrate insertion grooves of the buffer of the present invention, and are orthogonal to the substrate surface. The four sides of the rectangular parallelepiped are fitted by the buffer. Then, a long fixing tool is wound along the L-shape of the buffer and fastened. When the shock absorber has a fixture guide groove, the fixture is wound along the fixture guide groove.
Note that a dummy glass substrate may be arranged as the outermost glass substrate.
Embodiments other than the glass substrate package using the buffer of the present invention will be described below.
In the same manner as described above, a plurality of glass substrates are arranged in parallel at a predetermined interval to form a rectangular parallelepiped, and the corners of each substrate are inserted into the substrate insertion grooves of the buffer of the present invention, respectively, with respect to the surface of the substrate. The four sides of the rectangular body which are orthogonal to each other are fitted by the buffer. Thereafter, a long fixture is wound along the fixture guide groove along the L-shape of the buffer, fixed by fastening, and a package is formed. Then, the package is packaged with a heat-shrinkable resin film. Then, the film is subjected to a heat treatment to be thermally shrunk and shrink-wrapped.
When packing the package with the heat-shrinkable resin film as necessary, after storing the package in a bag-shaped or tubular-shaped film, preferably heat-sealing and sealing the end of the film. Alternatively, the film may be heat-shrinked to adhere to the package.
The above-mentioned package has a feature in that a package in which a plurality of glass substrates are integrally packaged using the buffer of the present invention is shrink-wrapped using a heat-shrinkable resin film, and thereby, Even with the glass substrate package, the packaging operation of the package is facilitated, and automatic packaging becomes possible. In the package after packaging, since the heat-shrinkable film has no slack at all, the film does not come into contact with the outermost substrate of the package and the glass substrate is not contaminated. It is not necessary to use the buffer, and the buffer can be used effectively and the efficiency is high. Furthermore, since the entire buffer is pressed from the outside by the shrinkage stress of the film, the buffer and the glass substrate are satisfactorily fixed integrally, so that the groove of the glass substrate is not dislodged or damaged, and also, during transportation, Rubbing between the glass substrate and the buffer due to the vibration is drastically reduced, thereby preventing the glass substrate from being scratched or adhering dust and keeping the glass substrate clean.
Heat-shrinkable resin films used for shrink packaging include polyolefin-based resin films and polyvinyl chloride-based resin films. Polyvinyl chloride-based resins provide processability and flexibility during extrusion film formation due to their properties. For this purpose, a large amount of plasticizers and stabilizers are added in many types. These additives exude to the surface of a film or the like over time after film formation, or cause a very small amount of volatilization even at room temperature, thereby deteriorating the cleanliness of a work place for packaging a glass substrate, or In addition, there is a possibility that an additive attached to a hand during packaging and handling of a glass substrate may cause a serious contamination problem such as indirect contact with the glass substrate. Further, in order to prevent dust from entering from outside during transportation, it is desirable to heat seal the film and hermetically seal the package, but polyvinyl chloride resin has poor heat seal suitability, and It is preferable to use a polyolefin resin film because an expensive device such as a high-frequency sealing device or the like is required.
As the polyolefin-based resin film, a single- or multi-layered product of a polypropylene-based resin or a polyethylene-based resin, or a crosslinked or non-crosslinked type is preferably used.
Such a polyolefin-based resin film preferably has a heat shrinkage at 120 ° C. of preferably at least 15% in at least one of the vertical and horizontal directions, more preferably 90% or less. Most preferably, it is 20% or more. More preferably, it is 15% or more and 90% or less in both the vertical and horizontal directions. When heat shrinking is performed in this range, the package is tightly shrink-wrapped without loosening, and there is no risk that the glass substrate comes into contact with the film to contaminate the glass substrate. The heat shrinkage is a value measured at 120 ° C. according to the method of ASTM No. D-2732.
The maximum heat shrinkage stress at 120 ° C. is 0.15 N / mm in at least one of the vertical and horizontal directions.²More preferably, more preferably 5 N / mm²The following is good. Most preferably 0.2 N / mm²Above 4.5 N / mm²It is as follows. More preferably, 0.15 N / mm in both the vertical and horizontal directions.²More than 5N / mm²It is as follows.
When the maximum heat shrinkage stress at 120 ° C. is within the above range, the package is tightly shrink-wrapped without loosening, and even when the film is pressed during handling, the film does not easily contact the glass substrate and the glass substrate is cleaned. Sex is maintained. In addition, since the heat shrinkage stress is appropriate, the film can be hermetically sealed without breaking at the corners at the time of packaging, and the intrusion of dust from the outside can be blocked.
The maximum heat shrinkage stress is a value measured at 120 ° C. according to ASTM D-2838.
Further, the thickness of the polyolefin resin film is preferably 10 μm or more, more preferably 200 μm or less. Even more preferably, it is 20 μm or more, and most preferably 180 μm or less. When the thickness is in this range, the film has an appropriate waist, and thus the packaging workability of the package can be performed easily, efficiently, and efficiently. In addition to being able to perform heat sealing with high welding strength, it has a breaking strength to withstand impact during transportation and handling.
The fixing tool used in the present invention may be a string-shaped or tape-shaped fixing tool. For example, a polypropylene tape is preferably used.
Further, although the buffer of the present invention is used in a set of four, the four may be completely the same or may have different configurations. For example, when packing a large glass substrate, May be made large and thick to withstand the weight of the glass substrate.
In addition, the buffer of the present invention may be used in a set other than the above four, for example, a stopper for preventing the buffer of the present invention from moving to the inner bottom of a plastic container or a plastic cardboard box having an open top. The two are fixed in the opposite direction by using a glass substrate, and the glass substrate is inserted and fixed from the upper opening, and if necessary, the glass substrate may be covered with a box so that dust does not enter from the upper opening. It can also be used for storage of substrates. In this case, by attaching the buffer or the plate-shaped plastic foam of the present invention to the glass lid, it can be used as a transport container.
<Example>
(Example 1, Reference Example 1)
(Glass substrate)
Mother glass for liquid crystal display
Dimension: 600mm × 720mm
Thickness: 0.7mm
(Foam)
Resin material: Expansion ratio is 20cm³/ G ethylene / propylene random copolymer
Average particle size of expanded resin particles: 3.6 mm
Fusion rate: 86%
Compression modulus: 549 N / cm²
Compression elasticity index: 27.5
(Buffer)
Glass substrate capacity: 26
External dimensions;
Short side: 250mm
Long side: 350mm
Length (length orthogonal to short side and long side): 300mm
Maximum thickness: 32mm
Board insertion groove;
Width: 2.4mm
Depth: 12mm
Pitch: 20mm
Sectional shape of the ridge: a trapezoid having a wall surface of 6.5 mm perpendicular to the bottom surface of the substrate insertion groove and a top having a width of a flat portion of 8 mm and a height of 5.5 mm (FIG. 4C)
(Fixture guide groove)
A total of two cushions having a width of 30 mm were provided at １／ of the length (300 mm) of the buffer from both sides. The depth of the groove was 1 mm at the end of the L-shape, an arc-shaped chamfer with a radius of 20 mm was formed at the corner, and the depth of the groove at the connection between the groove bottom and the chamfer was 4 mm.
(Free drop test)
The above-mentioned glass substrate was packaged as shown in FIG. 2 using four of the above-mentioned buffer bodies to obtain a package. A free-fall test was performed to evaluate the buffer performance of the buffer in the package. As Reference Example 1, the same test was performed using exactly the same buffer except that the fusion ratio was 65%.
Test condition
Fall height: 30cm
Falling surface of package: only at the location of the package
Number of drops: 3 times
The package of Example 1 did not fall off the glass substrate at all after falling three times, and kept the glass substrate packaged state before the test, and showed no damage to the glass substrate. Further, regarding the adhesion of the buffer dust to the glass substrate surface, no dust having a size observable visually was observed at all.
In the package of Reference Example 1, although the glass substrate did not fall off, a minute chip was generated at the end of the glass substrate which was in contact with the groove in the long side direction of the buffer disposed on the ground. It is considered that as a result of closely observing the buffer in order to investigate the cause of the occurrence of the chipping, a crack was generated between the foamed beads, and the glass substrate cut into the buffer by a drop impact. In addition, it was found that the foamed beads had fallen off, indicating that the durability against repeated use was inferior to that of the buffer of Example 1. That is, it is considered that since the fusion rate of the buffer was less than 70%, the mechanical strength inherent in the buffer was inferior, and excessive strain occurred when subjected to a drop impact.
(Example 2, Comparative Example 1)
(Glass substrate)
Mother glass for liquid crystal display
Dimensions: 550mm x 650mm
Thickness: 0.7mm
(Foam)
Resin material: foaming ratio is 10cm³/ G and resin density 0.930g / cm³Crosslinked polyethylene
Average particle size of expanded particles: 2.8 mm
Fusion rate: 98%
Compression modulus: 412 N / cm²
Compression elasticity index: 41.2
(Buffer)
Glass substrate capacity: 12
External dimensions;
Short side: 210mm
Long side: 310mm
Length (length perpendicular to short side and long side): 240mm
Maximum thickness: 23mm
Board insertion groove;
Width: 1.5mm
Depth: 7mm
Pitch: 20mm
Cross-sectional shape of the ridge: a 3.5 mm wall surface perpendicular to the bottom surface of the substrate insertion groove and 3.5 mm in height at the top (shape of FIG. 4B)
(Fixture guide groove)
A total of two cushions having a width of 25 mm were provided at １／ of the length (240 mm) of the buffer from both sides. A groove is formed from the position of 50 mm toward the corner from the end of the L-shape to the corner, an arc-shaped chamfer having a radius of 10 mm is formed in the corner, and the connection between the bottom of the groove and the chamfer is formed. The depth of the groove in the portion was 3 mm.
〔Vibration test〕
The above-mentioned glass substrate was packaged as shown in FIG. 2 using four of the above-mentioned buffer bodies to obtain a package. A vibration test was performed to evaluate the performance of fixing the buffer to the glass substrate in this package. The vibration test was performed by fixing the package to a vibration table of a vibration test apparatus and following the test method of JIS Z0232. Further, as Comparative Example 1, the same test was performed using exactly the same buffer, except that the depth of the fixture guide groove was set to 1 mm at all portions.
Test condition
Vibration direction: up and down
Vibration waveform: sine wave
Sweep: logarithmic sweep (frequency 5 to 100 Hz)
Sweep speed 0.5 octave / min
Vibration acceleration: ± 0.75G
Vibration time: 30 minutes
When the packaged state of the glass substrate was visually observed after the end of the vibration test, in the package of Example 2, although the glass substrate was slightly loosened, no glass substrate dropped off from the substrate insertion groove. . Further, regarding the adhesion of the buffer dust to the glass substrate surface, no dust having a size observable visually was observed at all.
In the package of Comparative Example 1, 8 minutes after the start of the vibration test, the glass substrate came off in the substrate insertion groove on the long side of the upper two buffers, and there was a danger of breakage due to contact with the adjacent glass substrate. The test was stopped because of it.
Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
This application is based on Japanese Patent Application (No. 2000-396934) filed on Dec. 27, 2000, the contents of which are incorporated herein by reference.
<Industrial applicability>
As described above, when the shock absorber of the present invention is fastened with the fixture, the fastening force of the fixture is prevented from being concentrated on the corners, so that the glass substrate can be satisfactorily pressed against the glass substrate even at the ends. The groove of the substrate is not displaced, and a good protective effect is exhibited. In particular, the cushioning body of the present invention has its dimensions adjusted, and by using a foam having a specific characteristic as a constituent material, the glass substrate can be easily packed and removed, which is also suitable for automation. It becomes. In addition, it is excellent in dust generation and durability, adapted to work in a clean room, and can withstand repeated use many times. Therefore, in the package of the present invention in which a plurality of glass substrates are packed using the buffer of the present invention, the internal glass substrate is reliably protected against vibration impact and drop impact during transport, and defective products are protected. Occurrence is greatly reduced.
[Brief description of the drawings]
FIG. 1 is a perspective view of one embodiment of the shock absorber of the present invention.
FIG. 2 is a perspective view of one embodiment of the package of the present invention.
3 (a) to 3 (e) are schematic cross-sectional views of an embodiment of the buffer according to the present invention.
FIGS. 4A to 4C are schematic cross-sectional views showing a configuration example of the substrate insertion groove of the buffer of the present invention.
In the drawings, reference numeral 1 denotes a buffer, 2 denotes a substrate insertion groove, 3 denotes a fixture guide groove, 4 denotes a ridge, 21 denotes a glass substrate, 22 denotes a fixture, 31 denotes a wall surface of the buffer, and 32 denotes a substrate. The bottom of the insertion groove, 33 is the L-shaped end, 34 and 34 'are the L-shaped corners, 35 is the bottom of the fixture guide groove, 36 is a chamfer, 37 is a cutout groove, 38 is a projection, 39 Is a concave portion.

Claims

A buffer for a glass substrate comprising a polyolefin bead foam, having a substantially L-shaped cross section according to the shape of the corner of the glass substrate, and forming the corner of the glass substrate on the inner surface along the L-shape. A plurality of substrate insertion grooves for fixing the two side ends are provided, and the outer surface has at least one fixing tool guide groove formed along the L-shape, and the bottom of the fixing tool guide groove is formed. A buffer for a glass substrate, wherein the thickness of the buffer as a reference gradually decreases from both ends of the L-shape to the corners.

2. The glass substrate buffer according to claim 1, wherein the bottom of the fixture guide groove at the corner is chamfered.

A buffer for a glass substrate comprising a polyolefin bead foam, having a substantially L-shaped cross section according to the shape of the corner of the glass substrate, and forming the corner of the glass substrate on the inner surface along the L-shape. A buffer for a glass substrate, wherein a plurality of substrate insertion grooves for fixing two side ends are provided, and the thickness of the buffer gradually decreases from both ends of the L-shape to the corners.

A buffer for a glass substrate comprising a polyolefin bead foam, having a substantially L-shaped cross section according to the shape of the corner of the glass substrate, and forming the corner of the glass substrate on the inner surface along the L-shape. A buffer for a glass substrate, wherein a plurality of substrate insertion grooves for fixing two side ends are provided, and convex portions are formed at both ends outside the L-shape.

The buffer for a glass substrate according to claim 4, wherein an outer corner of the buffer is chamfered.

The buffer for a glass substrate according to any one of claims 1 to 5, wherein a cutout groove is provided inside the buffer in a direction perpendicular to the substrate insertion groove.

The maximum thickness of the buffer is 10 to 60 mm, the ratio of the two sides of the L shape is 1.0 to 3.0 based on the short side, and the groove width of the substrate insertion groove is 1.0 to 4 of the thickness of the glass substrate. The buffer for a glass substrate according to any one of claims 1 to 5, wherein the buffer body has a groove depth of 3 to 15 mm and a groove pitch of 6 to 100 mm.

The polyolefin bead foam has an average particle diameter of expanded particles of 1.5 to 5.0 mm, a fusion rate of 70% or more, a compression elasticity index of 3.9 to 490, and a recovery rate of 60% or more. Item 6. The glass substrate buffer according to any one of Items 1 to 5.

Multiple glass substrates,
The glass substrate buffer according to claim 1, wherein the plurality of glass substrates are held in a state of being arranged in parallel with a predetermined interval by inserting four corners of the glass substrate into a substrate insertion groove. A package comprising a long fixing tool wound for fastening along the fixing tool guide groove of the shock absorber.

Multiple glass substrates,
5. The buffer for a glass substrate according to claim 3, wherein the plurality of glass substrates are held in a state of being arranged in parallel at a predetermined interval by inserting four corners of the glass substrate into the substrate insertion groove. A package comprising: a body; and an elongate fixing device wound around the outside of the buffer along an L-shape.