JPH0588895B2 - - Google Patents
Info
- Publication number
- JPH0588895B2 JPH0588895B2 JP63227626A JP22762688A JPH0588895B2 JP H0588895 B2 JPH0588895 B2 JP H0588895B2 JP 63227626 A JP63227626 A JP 63227626A JP 22762688 A JP22762688 A JP 22762688A JP H0588895 B2 JPH0588895 B2 JP H0588895B2
- Authority
- JP
- Japan
- Prior art keywords
- foam sheet
- resin
- foaming
- water
- ratio
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
- 239000006260 foam Substances 0.000 claims description 45
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 claims description 33
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 28
- 229920005989 resin Polymers 0.000 claims description 25
- 239000011347 resin Substances 0.000 claims description 25
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 20
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims description 20
- 238000005187 foaming Methods 0.000 claims description 18
- 239000004088 foaming agent Substances 0.000 claims description 13
- 239000004604 Blowing Agent Substances 0.000 claims description 10
- 239000001569 carbon dioxide Substances 0.000 claims description 10
- 229910002092 carbon dioxide Inorganic materials 0.000 claims description 10
- 229910052757 nitrogen Inorganic materials 0.000 claims description 9
- 239000003570 air Substances 0.000 claims description 7
- 239000000203 mixture Substances 0.000 claims description 7
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 229920001890 Novodur Polymers 0.000 claims description 3
- 238000000034 method Methods 0.000 claims description 3
- 238000007599 discharging Methods 0.000 claims description 2
- 238000010521 absorption reaction Methods 0.000 description 12
- 229920005990 polystyrene resin Polymers 0.000 description 11
- 239000007789 gas Substances 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000001125 extrusion Methods 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- 239000003463 adsorbent Substances 0.000 description 3
- 235000013305 food Nutrition 0.000 description 3
- 230000001965 increasing effect Effects 0.000 description 3
- KAKZBPTYRLMSJV-UHFFFAOYSA-N Butadiene Chemical compound C=CC=C KAKZBPTYRLMSJV-UHFFFAOYSA-N 0.000 description 2
- 239000004793 Polystyrene Substances 0.000 description 2
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- 239000001273 butane Substances 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- 239000003205 fragrance Substances 0.000 description 2
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 description 2
- OFBQJSOFQDEBGM-UHFFFAOYSA-N n-pentane Natural products CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 2
- 238000004806 packaging method and process Methods 0.000 description 2
- 229920002223 polystyrene Polymers 0.000 description 2
- 239000003755 preservative agent Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 241000251468 Actinopterygii Species 0.000 description 1
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 1
- 239000004677 Nylon Substances 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 229910021536 Zeolite Inorganic materials 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 239000008280 blood Substances 0.000 description 1
- 210000004369 blood Anatomy 0.000 description 1
- 229920006026 co-polymeric resin Polymers 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 150000003983 crown ethers Chemical class 0.000 description 1
- 239000003599 detergent Substances 0.000 description 1
- PXBRQCKWGAHEHS-UHFFFAOYSA-N dichlorodifluoromethane Chemical compound FC(F)(Cl)Cl PXBRQCKWGAHEHS-UHFFFAOYSA-N 0.000 description 1
- 235000019404 dichlorodifluoromethane Nutrition 0.000 description 1
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 235000013399 edible fruits Nutrition 0.000 description 1
- 229920001971 elastomer Polymers 0.000 description 1
- 239000000806 elastomer Substances 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000010097 foam moulding Methods 0.000 description 1
- 235000011389 fruit/vegetable juice Nutrition 0.000 description 1
- 229920005669 high impact polystyrene Polymers 0.000 description 1
- 239000004797 high-impact polystyrene Substances 0.000 description 1
- 229920001519 homopolymer Polymers 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 235000013372 meat Nutrition 0.000 description 1
- 239000004745 nonwoven fabric Substances 0.000 description 1
- 239000002667 nucleating agent Substances 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
- 239000005020 polyethylene terephthalate Substances 0.000 description 1
- 229920005672 polyolefin resin Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000001294 propane Substances 0.000 description 1
- 230000002940 repellent Effects 0.000 description 1
- 239000005871 repellent Substances 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 239000000057 synthetic resin Substances 0.000 description 1
- 239000000454 talc Substances 0.000 description 1
- 229910052623 talc Inorganic materials 0.000 description 1
- CYRMSUTZVYGINF-UHFFFAOYSA-N trichlorofluoromethane Chemical compound FC(Cl)(Cl)Cl CYRMSUTZVYGINF-UHFFFAOYSA-N 0.000 description 1
- 239000010457 zeolite Substances 0.000 description 1
Landscapes
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
- Extrusion Moulding Of Plastics Or The Like (AREA)
- Molding Of Porous Articles (AREA)
Description
（産業上の利用分野）
本発明は、新規な特性を有するポリスチレン系
樹脂発泡性シートに関し、特に優れた吸水性能を
有するポリスチレン系樹脂発泡シートに関する。
（従来の技術）
従来より製造されているポリスチレン系樹脂よ
りなる発泡シートは、独立気泡で形成されている
ため撥水性であつた。したがつて、吸水性が要求
される生鮮食品の包装にポリスチレン系樹脂発泡
シートを使用するためには、不織布シートを重ね
合せて吸水性として使用しなければならなかつ
た。
又、合成樹脂の表面品質改善のために各種の薬
剤を混練して成形することが行なわれているが、
ポリスチレン系樹脂よりなる発泡シートは前述の
ように独立気泡体であるため、薬剤が気泡内部に
閉じ込められてしまい、改善効果は十分に発現で
きなかつた。それ故、ポリスチレン系樹脂発泡シ
ートの表面を改善するためには、発泡シートの表
面に直接薬剤を塗布することが行なわれてきた
が、このような方法では加工工程を必要とするば
かりでなく、持続性の点で問題があつた。
（発明が解決しようとする課題）
本発明者は上記の欠点をなくし、ポリスチレン
系樹脂よりなる発泡シートに吸水性を賦与するた
めに検討した結果、発泡剤として、従来使用され
ていた易揮発性液体の代わりに窒素、炭酸ガス、
空気などの常温、常圧で気体状であり、且つ、ポ
リスチレンとの相溶性もよくないガスを使用し、
特定の発泡条件を選定することにより吸水性を有
する発泡シートが得られることを見出し、本発明
を完成するに至つたもので、本発明の目的は吸水
性を有するポリスチレン系樹脂発泡シート及びそ
の製造方法を提供するにある。
（課題を解決するための手段）
すなわち、本発明の要旨は、厚さ0.3〜３mmの
スチレン系樹脂発泡シートで、厚さ１mmあたりの
単位重量が120〜600ｇ／m2であり、表面には微細
な気泡を有する皮付部分と、気泡が破れた繊維状
部分が縞状に存在し、発泡シートの独立気泡率が
50％以下であることを特徴とする吸水性を有する
スチレン系樹脂発泡シートである。
そして、更に、本発明の要旨は、押出機にスチ
レン系樹脂を供給し、加熱溶融し、押出機の途中
から窒素、炭酸ガス、空気、水、又はこれ等の混
合物からなる発泡剤を供給し、次いで低圧領域へ
排出して発泡シートを製造する方法において発泡
剤をスチレン系樹脂１Kgに対し、0.2〜0.8モルの
割合で使用し下記による発泡効率が50％以下とな
る様に押出すことを特徴とする吸水性を有するス
チレン系樹脂発泡シートの製造方法である。
発泡効率＝得られる発泡シートの発泡倍率（／Kg）／
38×（樹脂１Kg当り使用した発泡剤のモル数）×100
本発明について詳細に説明する。
本発明において使用する発泡剤は窒素、炭酸ガ
ス、空気、水又はこれらの混合物である。従来ポ
リスチレンの発泡剤としてフレオン、ブタン、な
どのポリスチレン樹脂とは良好な相溶性を有し、
常温で加圧すると容易に液化する易揮発性液体を
使用している。しかし、このような易揮発性液体
を発泡剤として使用した場合、得られる発泡シー
トは独立気泡のシートとなり吸水性とはならな
い。又、特殊な例として窒素、炭酸ガス、空気を
発泡剤として使用した場合があるが（例えば特開
昭58−126127号、特願昭63−35690号参照）、何れ
も独立気泡の発泡シートが目的とされていた。
本発明では、上述の窒素、炭酸ガス、空気又は
水などの発泡剤をスチレン系樹脂１Kgに対して
0.2〜0.8モルの割合で使用する。使用量が0.2モル
以下では押出発泡成形が不安定で独立気泡の発泡
シートとなり易く、又0.8モル以上では気泡は破
泡するが、発泡シートが脈流して厚さのある外観
良好な発泡シートは得られない。
そして、本発明では発泡効果が50％以下となる
ような条件を選定することが重要である。発泡効
率とは、次式で定義されるものである。
発泡効率＝得られる気泡シートの発泡倍率（／Kg）／
38×（樹脂１Kg当り使用した発泡剤のモル数）×100
この式において38とは標準状態における気体
１モルの容積を190℃に換算した値であるので、
該式は樹脂１Kgあたり使用した発泡剤の容積に対
する得られる発泡シートの発泡倍率ということに
なる。
本発明では、発泡倍率を50％以下の値になるよ
うに選定することで、得ようとする発泡シートの
所望の発泡倍率に相当する発泡剤量よりも多くの
発泡剤を使用して倍率を理論値の50％以下に抑え
ることである。具体的には、樹脂温度を高くして
樹脂粘度を下げることや、口金寸法を大きくした
り、出口に向かつて開放したり、押出速度を下げ
て圧力を下げることにより実施できる。
本発明におけるスチレン系樹脂とはスチレンの
単独重合体にとどまらず、スチレン分を50％以上
含有する共重合体を含む。
又、発泡剤は前述のように窒素、炭酸ガス、空
気、水を樹脂１Kg当り0.2〜0.8モル使用するが、
他に一般に使われている易揮発性液状発泡剤、例
えばプロパン、ブタン、フロン11、フロン12等を
窒素、炭酸ガス、空気の使用量と同量以下使用す
ることは妨げない。
本発明の発泡シートを製造するに当り、スチレ
ン系樹脂100重量分に対し、各種オレフイン系樹
脂やスチレン系エラストマーを５〜20重量分の範
囲で用いることによつて、特に好ましい発泡シー
トが得られる。又、この他に一般の気泡核剤、着
色剤等も使用できるが、特にこの発泡シートの機
能を高める目的で次のような添加剤を使用するこ
とが出来る。すなわち、例えば生鮮食品の鮮度保
持剤としてゼオライト、クラウンエーテル等の吸
着剤、吸着性樹脂、有機又は無機微粉末等の保水
剤、鉄粉等の脱酵素剤や各種香料を入れることも
できる。
発泡剤と混合された樹脂は、押出機の口金から
大気中へ排出され発泡するが、口金としては、厚
さ0.2〜1.0mmの円形の細隙を用い、発泡した円筒
状シートは、それより大きめの円筒に沿わせて冷
却しながら引き取る。
得られた発泡シートは、厚さが0.3〜３mmを有
し、厚さ１mm当りの単位重量が120〜600ｇ／m2の
範囲内にあるものが最も良好な外観、二次成型性
を有する。
そして、その外観は微細な気泡を有する皮付部
分と、気泡が破れて繊維状になつた部分とが縞状
に交互に存在し、全体として独立気泡率は50％以
下となつている。このために発泡シートは他のス
チレン系樹脂発泡シートには見られない吸水性を
示すが、この吸水性のために水分が反対側へ浸み
出すのを避ける目的で片面に厚さ20〜200μの
HIPS、PE、PP、ナイロン、PET等のフイルム
を積層して用いることができる。
更に、本発明の実施例をもつて具体的に説明す
る。
実施例 １
内径50mmのシリンダーと、内径65mmのシリンダ
ーとが縦に連結された押出機を用い、内径50mmの
シリンダーの中央部付近に発泡剤注入口を設けた
ものを使用した。
内径50mmの押出機にポリスチレン樹脂（旭化成
社製 スタイロン＃683）85部と、スチレンとブ
タジエンとの共重合樹脂（新日本化学社製エスチ
レンＳ−61）15部とタルク1.5部との混合物を供
給した。
内径50mmの押出機内で溶融されたポリスチレン
樹脂混合物１Kgに対して0.26モルの割合で窒素ガ
スを発泡剤注入口より圧入し、スクリユーで均一
に混合し、この混合物を内径65mmの押出機に送
り、ここで樹脂温度を190℃に調整し、口金から
大気圧下に１時間当り20.3Kgの割合で押出した。
口金としては、出口間隙が0.45mm、直径が60mm
のサーキユラーダイを使用した。このときの口金
の圧力は205Kg／cm2であつた。
押出された樹脂は円筒状に成型されており、口
金を出ると同時に発泡し口金の先に設置された円
筒に被せられ、円筒に沿つて軸方向に進行し、カ
ツターによりスリツトされ、引取機によつて引き
取り、シート状の発泡シートとなつた。
この発泡シートは、冷却後、厚さ1.13mm、密度
0.305ｇ／cm3で厚さ１mm当りの重量は305ｇ／m2で
あつた。この発泡シートの表面写真を第１図ａ、
裏面写真を第１図ｂ、切断面写真を第１図Ｃとし
て示す。この写真より明らかなように、表面には
微細な気泡を有する皮付部分と、気泡が破れた繊
維状部分が縞状に存在していることが観測されて
いる。発泡効率は33％であつた。発泡シートの独
立気泡率は、空気比較式比重計（東芝ベークマン
社製）１−１／２−１気圧法で０％であつた。
吸水量は試験片（100mm×100mm）の重量を測定
し、24時間0.2％食器用洗剤水溶液に浸漬した後、
ガーゼで水滴を拭き取つた後の重量増を測定し、
試験片の元の重量に対する増加割合を計算した。
実施例１では88.8％／24時間の吸水量であつた。
実施例 ２〜８
第１表に示す条件のもとに、実施例１で使用し
た押出機を使用し、実施例１と同様の操作によつ
て発泡シートを製造した。得られた発泡シートの
性状を第１表に示す。尚、実施例２，３の切断面
写真をそれぞれ第２図、第３図に示す。
実施例 ９
この実施例は実施例１と同様に実施したが、た
だ窒素ガスの代わりに二酸化炭素ガスを樹脂混合
物１Kgに対して0.60モル圧入した。口金としては
出口間隙0.30mm、直径が60mmのサーキユラーダイ
を使用し、この時の口金の圧力は130Kg／cm2であ
つた。
得られた発泡シートは厚さ1.04mm、密度0.191
ｇ／cm3で、厚さ１mm当りの単位重量は197ｇ／m2
であり、表面には微細な気泡を有する皮付部分と
気泡が破れた繊維状部分が縞状に存在していた。
発泡効率は22％で、発泡シートの独立気泡率は
０％であり、吸水量は126.2％／24時間であつた。
比較例 １〜４
発泡効率が50％以上の場合を比較例として示
す。即ち、第１表に示す条件のもとに、実施例１
で使用した押出機を使用し、実施例１と同様の操
作によつて発泡シートを製造した。得られた発泡
シートの性状を第１表に示す。尚、比較例１の切
断面写真を第４図に示す。
(Industrial Application Field) The present invention relates to a polystyrene resin foam sheet having novel properties, and particularly to a polystyrene resin foam sheet having excellent water absorption performance. (Prior Art) Foamed sheets made of polystyrene resin that have been conventionally manufactured are water repellent because they are formed of closed cells. Therefore, in order to use polystyrene resin foam sheets for packaging fresh foods that require water absorbency, it has been necessary to overlap nonwoven fabric sheets and use them for water absorption. In addition, in order to improve the surface quality of synthetic resins, various chemicals are kneaded and molded.
Since the foam sheet made of polystyrene resin is a closed cell as described above, the drug is trapped inside the cells, and the improvement effect cannot be fully expressed. Therefore, in order to improve the surface of polystyrene resin foam sheets, it has been done to apply chemicals directly to the surface of the foam sheets, but such methods not only require processing steps, but also There was a problem with sustainability. (Problems to be Solved by the Invention) As a result of studies to eliminate the above-mentioned drawbacks and impart water absorbency to a foamed sheet made of polystyrene resin, the inventors of the present invention found that a foaming agent that is easily volatile, which has been conventionally used, was used as a foaming agent. Nitrogen, carbon dioxide gas instead of liquid,
Using a gas such as air, which is gaseous at room temperature and pressure, and which is not compatible with polystyrene,
It was discovered that a foamed sheet with water absorbency can be obtained by selecting specific foaming conditions, and the present invention was completed.The purpose of the present invention is to provide a polystyrene resin foam sheet with water absorption and its production. We are here to provide you with a method. (Means for Solving the Problems) That is, the gist of the present invention is to provide a styrene resin foam sheet with a thickness of 0.3 to 3 mm, a unit weight per 1 mm of thickness of 120 to 600 g/ m2 , and a The skinned part with fine air bubbles and the fibrous part with broken air bubbles exist in a striped pattern, and the closed cell ratio of the foam sheet is
This is a styrene resin foam sheet with water absorption of 50% or less. Furthermore, the gist of the present invention is to supply a styrene resin to an extruder, heat and melt it, and supply a blowing agent consisting of nitrogen, carbon dioxide, air, water, or a mixture thereof from the middle of the extruder. Then, in the method of manufacturing a foamed sheet by discharging it to a low pressure area, the foaming agent is used at a ratio of 0.2 to 0.8 mol per 1 kg of styrene resin, and extrusion is performed so that the foaming efficiency is 50% or less as shown below. This is a method for producing a styrenic resin foam sheet having a characteristic water absorbing property. Foaming efficiency = foaming ratio of the resulting foam sheet (/Kg)/
38×(Number of moles of blowing agent used per 1 kg of resin)×100 The present invention will be explained in detail. The blowing agent used in the present invention is nitrogen, carbon dioxide, air, water or a mixture thereof. Conventionally used as a foaming agent for polystyrene, it has good compatibility with polystyrene resins such as freon and butane.
It uses an easily volatile liquid that easily liquefies when pressurized at room temperature. However, when such an easily volatile liquid is used as a foaming agent, the foamed sheet obtained becomes a sheet of closed cells and does not have water absorbency. In addition, as a special example, there are cases where nitrogen, carbon dioxide gas, or air is used as a foaming agent (see, for example, Japanese Patent Application Laid-Open No. 126127/1982 and Japanese Patent Application No. 35690/1983), but in both cases, closed-cell foam sheets are used. It was intended as a purpose. In the present invention, the above-mentioned blowing agent such as nitrogen, carbon dioxide gas, air or water is added to 1 kg of styrene resin.
Use in a proportion of 0.2 to 0.8 mol. If the amount used is less than 0.2 mol, the extrusion foam molding will be unstable and the foam sheet will tend to be closed cells, and if it is more than 0.8 mol, the cells will burst, but the foam sheet will pulsate and the foam sheet will be thick and have a good appearance. I can't get it. In the present invention, it is important to select conditions such that the foaming effect is 50% or less. Foaming efficiency is defined by the following formula. Foaming efficiency = foaming ratio of the resulting foam sheet (/Kg)/
38 x (Number of moles of blowing agent used per 1 kg of resin) x 100 In this formula, 38 is the volume of 1 mole of gas in standard conditions converted to 190°C, so
This formula is the foaming ratio of the resulting foam sheet relative to the volume of foaming agent used per 1 kg of resin. In the present invention, by selecting the foaming ratio to be a value of 50% or less, the foaming ratio is increased by using a larger amount of foaming agent than the amount of foaming agent corresponding to the desired foaming ratio of the foam sheet to be obtained. The goal is to keep it below 50% of the theoretical value. Specifically, this can be carried out by increasing the resin temperature to lower the resin viscosity, increasing the size of the nozzle, opening it towards the outlet, or lowering the pressure by lowering the extrusion speed. The styrenic resin in the present invention is not limited to a styrene homopolymer, but also includes a copolymer containing 50% or more of styrene. In addition, as blowing agents, 0.2 to 0.8 moles of nitrogen, carbon dioxide, air, and water are used per 1 kg of resin, as mentioned above.
It is not prohibited to use other commonly used readily volatile liquid foaming agents, such as propane, butane, Freon 11, Freon 12, etc., in an amount equal to or less than that of nitrogen, carbon dioxide, or air. In producing the foamed sheet of the present invention, a particularly preferable foamed sheet can be obtained by using various olefin resins or styrene elastomers in an amount of 5 to 20 parts by weight per 100 parts by weight of the styrene resin. . In addition, general cell nucleating agents, coloring agents, etc. can also be used, but the following additives can be used especially for the purpose of enhancing the functions of this foam sheet. That is, for example, adsorbents such as zeolite and crown ether, adsorbent resins, water-retaining agents such as organic or inorganic fine powders, deenzyme agents such as iron powder, and various fragrances may be added as freshness-preserving agents for fresh foods. The resin mixed with the foaming agent is discharged into the atmosphere from the extruder nozzle and foams.A circular slit with a thickness of 0.2 to 1.0 mm is used as the nozzle, and the foamed cylindrical sheet is Place it along a large cylinder and remove while cooling. The obtained foamed sheet has a thickness of 0.3 to 3 mm and a unit weight per 1 mm of thickness in the range of 120 to 600 g/m 2 has the best appearance and secondary moldability. Its appearance consists of skinned areas with fine air bubbles and areas where the air bubbles have burst and become fibrous, alternating in a striped pattern, with an overall closed cell ratio of 50% or less. For this reason, the foam sheet exhibits water absorption that is not seen in other styrene resin foam sheets, but due to this water absorption, a thickness of 20 to 200 μm is applied to one side to prevent water from seeping out to the other side. of
Films such as HIPS, PE, PP, nylon, and PET can be laminated and used. Further, the present invention will be specifically explained using examples. Example 1 An extruder was used in which a cylinder with an inner diameter of 50 mm and a cylinder with an inner diameter of 65 mm were connected vertically, and a blowing agent injection port was provided near the center of the cylinder with an inner diameter of 50 mm. A mixture of 85 parts of polystyrene resin (Styron #683 manufactured by Asahi Kasei Co., Ltd.), 15 parts of a copolymer resin of styrene and butadiene (Estyrene S-61 manufactured by Shin Nippon Chemical Co., Ltd.), and 1.5 parts of talc is supplied to an extruder with an inner diameter of 50 mm. did. Nitrogen gas was injected through the blowing agent inlet at a rate of 0.26 mol per kg of melted polystyrene resin mixture in an extruder with an inner diameter of 50 mm, mixed uniformly with a screw, and this mixture was sent to an extruder with an inner diameter of 65 mm. Here, the resin temperature was adjusted to 190°C, and the resin was extruded from a die under atmospheric pressure at a rate of 20.3 kg per hour. As for the base, the exit gap is 0.45mm and the diameter is 60mm.
A circular die was used. The pressure in the cap at this time was 205 kg/cm 2 . The extruded resin is molded into a cylindrical shape, and as soon as it leaves the nozzle, it foams, covers the cylinder installed at the tip of the nozzle, travels along the cylinder in the axial direction, is slit by a cutter, and is sent to a take-up machine. It was then collected and turned into a foam sheet. After cooling, this foam sheet has a thickness of 1.13mm and a density of
The weight per 1 mm of thickness was 305 g/m 2 at 0.305 g/cm 3 . The surface photograph of this foam sheet is shown in Figure 1a.
A photograph of the back surface is shown in FIG. 1B, and a photograph of the cut surface is shown in FIG. 1C. As is clear from this photograph, it has been observed that the surface has a skinned part with fine air bubbles and a fibrous part with broken air bubbles in a striped pattern. The foaming efficiency was 33%. The closed cell ratio of the foamed sheet was 0% as measured by an air comparison hydrometer (manufactured by Toshiba Bakeman Co., Ltd.) at 1-1/2-1 atm. The amount of water absorption was determined by measuring the weight of a test piece (100 mm x 100 mm), immersing it in a 0.2% dish detergent aqueous solution for 24 hours,
Measure the weight increase after wiping off the water droplets with gauze,
The percentage increase relative to the original weight of the specimen was calculated.
In Example 1, the water absorption amount was 88.8%/24 hours. Examples 2 to 8 Under the conditions shown in Table 1, foamed sheets were produced using the same extruder as in Example 1 and in the same manner as in Example 1. Table 1 shows the properties of the foamed sheet obtained. Incidentally, photographs of the cut surfaces of Examples 2 and 3 are shown in FIG. 2 and FIG. 3, respectively. Example 9 This example was carried out in the same manner as Example 1, except that 0.60 mol of carbon dioxide gas was injected per kg of resin mixture instead of nitrogen gas. A circular die with an exit gap of 0.30 mm and a diameter of 60 mm was used as the die, and the pressure in the die at this time was 130 Kg/cm 2 . The resulting foam sheet has a thickness of 1.04 mm and a density of 0.191.
g/cm 3 , and the unit weight per 1 mm thickness is 197 g/m 2
On the surface, a skinned part with fine air bubbles and a fibrous part with broken air bubbles were present in a striped pattern. The foaming efficiency was 22%, the closed cell ratio of the foam sheet was 0%, and the water absorption was 126.2%/24 hours. Comparative Examples 1 to 4 Cases where the foaming efficiency is 50% or more are shown as comparative examples. That is, under the conditions shown in Table 1, Example 1
A foamed sheet was produced using the same extruder as in Example 1 and in the same manner as in Example 1. Table 1 shows the properties of the foamed sheet obtained. Incidentally, a photograph of the cut surface of Comparative Example 1 is shown in FIG.
【表】
（効果）
以上述べたように、本発明は発泡剤として窒
素、炭酸ガス、空気又は水を使用し特定の条件の
もとに押出し発泡することにより、吸水性を有す
るスチレン系樹脂発泡シートが得られる。そし
て、スチレン系樹脂発泡シートが吸水性を有する
ため、これを熟成型して生鮮食品の包装に使用し
た場合、例えば冷蔵庫から取り出した果実の結露
水を吸収し、又魚や肉の生汁や血を吸収するので
日持ち、見栄えが良くなる等の効果が得られる。
更に、この発泡シートは吸水性を有するため、
印刷、エンボス等を施したものは従来のものに比
して、美麗な化粧紙、壁紙となり、吸湿性がある
ため結露や帯電による埃の付着も少ない。
また、発泡シートの製造時に各種の鮮度保持
剤、吸着剤、香料等を入れるとそれ等の性能が表
面品質として発揮される。[Table] (Effects) As described above, the present invention uses nitrogen, carbon dioxide gas, air, or water as a blowing agent and performs extrusion foaming under specific conditions to form styrene resin foams with water absorption properties. A sheet is obtained. Since the styrene resin foam sheet has water absorption properties, when it is aged and used for packaging fresh foods, it can absorb, for example, the condensed water from fruits taken out of the refrigerator, and the raw juices and blood from fish and meat. Since it absorbs water, it can have effects such as longer shelf life and improved appearance. Furthermore, since this foam sheet has water absorption properties,
Compared to conventional paper, printed or embossed paper can be used as beautiful decorative paper or wallpaper, and because it is hygroscopic, there is less condensation and less dust due to static electricity. Additionally, if various freshness-preserving agents, adsorbents, fragrances, etc. are added during the manufacture of foam sheets, their performance will be exhibited as surface quality.
第１図ａは、本発明の実施例１によつて得られ
た発泡シートの写真（約35倍）であつて、ａは表
面、ｂは裏面及びＣは切断面である。又、第２図
は本発明の実施例２によつて得られた発泡シート
の切断面写真、第３図は実施例３によつて得られ
た発泡シートの切断面写真である。第４図は比較
例１によつて得られた発泡シートの切断面写真で
ある。
FIG. 1a is a photograph (approximately 35x magnification) of the foam sheet obtained in Example 1 of the present invention, in which a is the front surface, b is the back surface, and C is the cut surface. Further, FIG. 2 is a photograph of a cut surface of a foam sheet obtained according to Example 2 of the present invention, and FIG. 3 is a photograph of a cross section of a foam sheet obtained according to Example 3 of the present invention. FIG. 4 is a photograph of a cut surface of the foam sheet obtained in Comparative Example 1.
Claims (1)
で、厚さ１mmあたりの単位重量が120〜600ｇ／m2
であり、表面には微細な気泡を有する皮付部分
と、気泡が破れた繊維状部分が縞状に存在し、発
泡シートの独立気泡率が50％以下であることを特
徴とする吸水性を有するスチレン系樹脂発泡シー
ト。 ２ 押出機にスチレン系樹脂を供給し、加熱溶融
し、押出機の途中から窒素、炭酸ガス、空気、
水、又はこれ等の混合物からなる発泡剤を供給
し、次いで低圧領域へ排出して発泡シートを製造
する方法において、発泡剤をスチレン系樹脂１Kg
に対し0.2〜0.8モルの割合で使用し、下記の式で
表される発泡効率が50％以下となる様に押出すこ
とを特徴とする請求項第１項記載のスチレン系発
泡シートを製造する方法。 発泡効率＝得られる発泡シートの発泡倍率（／Kg）／
38×（樹脂１Kg当り使用した発泡剤のモル数）×100[Claims] 1. A styrene resin foam sheet with a thickness of 0.3 to 3 mm, with a unit weight of 120 to 600 g/m 2 per 1 mm of thickness.
The foam sheet has a skinned part with fine air bubbles and a fibrous part with broken air bubbles in a striped pattern on the surface, and the closed cell ratio of the foam sheet is 50% or less. Styrenic resin foam sheet with 2. Supply styrene resin to the extruder, heat and melt it, and inject nitrogen, carbon dioxide, air,
A method of manufacturing a foam sheet by supplying a foaming agent consisting of water or a mixture thereof and then discharging it to a low pressure area, in which 1 kg of styrene resin is added to the foaming agent.
The styrenic foam sheet according to claim 1 is manufactured by using the styrenic foam sheet at a ratio of 0.2 to 0.8 mol to Method. Foaming efficiency = foaming ratio of the resulting foam sheet (/Kg)/
38 x (Number of moles of blowing agent used per 1 kg of resin) x 100
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63227626A JPH0276715A (en) | 1988-09-13 | 1988-09-13 | Water absorbent styrene-based resin foamed sheet and manufacture thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63227626A JPH0276715A (en) | 1988-09-13 | 1988-09-13 | Water absorbent styrene-based resin foamed sheet and manufacture thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0276715A JPH0276715A (en) | 1990-03-16 |
| JPH0588895B2 true JPH0588895B2 (en) | 1993-12-24 |
Family
ID=16863869
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63227626A Granted JPH0276715A (en) | 1988-09-13 | 1988-09-13 | Water absorbent styrene-based resin foamed sheet and manufacture thereof |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0276715A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001026079A (en) * | 1999-07-13 | 2001-01-30 | Jsp Corp | Laminate |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5674916A (en) * | 1995-04-27 | 1997-10-07 | The Dow Chemical Company | Extruded, open-cell microcellular alkenylaromatic polymer foams and process for making |
| CN1259878A (en) * | 1997-06-11 | 2000-07-12 | 陶氏化学公司 | Absorbent, extruded thermoplastic foams |
-
1988
- 1988-09-13 JP JP63227626A patent/JPH0276715A/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001026079A (en) * | 1999-07-13 | 2001-01-30 | Jsp Corp | Laminate |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0276715A (en) | 1990-03-16 |
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