JPS6233254B2 - - Google Patents
Info
- Publication number
- JPS6233254B2 JPS6233254B2 JP56175990A JP17599081A JPS6233254B2 JP S6233254 B2 JPS6233254 B2 JP S6233254B2 JP 56175990 A JP56175990 A JP 56175990A JP 17599081 A JP17599081 A JP 17599081A JP S6233254 B2 JPS6233254 B2 JP S6233254B2
- Authority
- JP
- Japan
- Prior art keywords
- particles
- container
- pressure
- blowing agent
- expanded
- 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
Links
- 239000002245 particle Substances 0.000 claims description 71
- 239000004604 Blowing Agent Substances 0.000 claims description 30
- 229920001155 polypropylene Polymers 0.000 claims description 17
- -1 polypropylene Polymers 0.000 claims description 12
- 239000002612 dispersion medium Substances 0.000 claims description 11
- 239000004743 Polypropylene Substances 0.000 claims description 10
- 229920005989 resin Polymers 0.000 claims description 10
- 239000011347 resin Substances 0.000 claims description 10
- 238000004519 manufacturing process Methods 0.000 claims description 9
- 238000010438 heat treatment Methods 0.000 claims description 5
- 229920000642 polymer Polymers 0.000 description 20
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 10
- 238000000034 method Methods 0.000 description 6
- 239000006260 foam Substances 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 3
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 239000004088 foaming agent Substances 0.000 description 3
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 3
- OFBQJSOFQDEBGM-UHFFFAOYSA-N n-pentane Natural products CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 3
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 description 3
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- RGSFGYAAUTVSQA-UHFFFAOYSA-N Cyclopentane Chemical compound C1CCCC1 RGSFGYAAUTVSQA-UHFFFAOYSA-N 0.000 description 2
- 239000004338 Dichlorodifluoromethane Substances 0.000 description 2
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 2
- IMNFDUFMRHMDMM-UHFFFAOYSA-N N-Heptane Chemical compound CCCCCCC IMNFDUFMRHMDMM-UHFFFAOYSA-N 0.000 description 2
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- PXBRQCKWGAHEHS-UHFFFAOYSA-N dichlorodifluoromethane Chemical compound FC(F)(Cl)Cl PXBRQCKWGAHEHS-UHFFFAOYSA-N 0.000 description 2
- 235000019404 dichlorodifluoromethane Nutrition 0.000 description 2
- 229920005674 ethylene-propylene random copolymer Polymers 0.000 description 2
- 238000005187 foaming Methods 0.000 description 2
- 229910001872 inorganic gas Inorganic materials 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000005022 packaging material Substances 0.000 description 2
- DDMOUSALMHHKOS-UHFFFAOYSA-N 1,2-dichloro-1,1,2,2-tetrafluoroethane Chemical compound FC(F)(Cl)C(F)(F)Cl DDMOUSALMHHKOS-UHFFFAOYSA-N 0.000 description 1
- PMPVIKIVABFJJI-UHFFFAOYSA-N Cyclobutane Chemical compound C1CCC1 PMPVIKIVABFJJI-UHFFFAOYSA-N 0.000 description 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
- 150000001338 aliphatic hydrocarbons Chemical class 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 239000001273 butane Substances 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- NEHMKBQYUWJMIP-NJFSPNSNSA-N chloro(114C)methane Chemical compound [14CH3]Cl NEHMKBQYUWJMIP-NJFSPNSNSA-N 0.000 description 1
- HRYZWHHZPQKTII-UHFFFAOYSA-N chloroethane Chemical compound CCCl HRYZWHHZPQKTII-UHFFFAOYSA-N 0.000 description 1
- 239000004035 construction material Substances 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 229940042935 dichlorodifluoromethane Drugs 0.000 description 1
- 229940087091 dichlorotetrafluoroethane Drugs 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 229960003750 ethyl chloride Drugs 0.000 description 1
- 229920005676 ethylene-propylene block copolymer Polymers 0.000 description 1
- 238000005188 flotation Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229940052308 general anesthetics halogenated hydrocarbons Drugs 0.000 description 1
- 235000011187 glycerol Nutrition 0.000 description 1
- 150000008282 halocarbons Chemical class 0.000 description 1
- DMEGYFMYUHOHGS-UHFFFAOYSA-N heptamethylene Natural products C1CCCCCC1 DMEGYFMYUHOHGS-UHFFFAOYSA-N 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 description 1
- 239000001095 magnesium carbonate Substances 0.000 description 1
- 229910000021 magnesium carbonate Inorganic materials 0.000 description 1
- 229940073584 methylene chloride Drugs 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- UOURRHZRLGCVDA-UHFFFAOYSA-D pentazinc;dicarbonate;hexahydroxide Chemical compound [OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[Zn+2].[Zn+2].[Zn+2].[Zn+2].[Zn+2].[O-]C([O-])=O.[O-]C([O-])=O UOURRHZRLGCVDA-UHFFFAOYSA-D 0.000 description 1
- 239000001294 propane Substances 0.000 description 1
- 229920001384 propylene homopolymer Polymers 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- CYRMSUTZVYGINF-UHFFFAOYSA-N trichlorofluoromethane Chemical compound FC(Cl)(Cl)Cl CYRMSUTZVYGINF-UHFFFAOYSA-N 0.000 description 1
- 229940029284 trichlorofluoromethane Drugs 0.000 description 1
- 239000003981 vehicle Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C44/00—Shaping by internal pressure generated in the material, e.g. swelling or foaming ; Producing porous or cellular expanded plastics articles
- B29C44/34—Auxiliary operations
- B29C44/3461—Making or treating expandable particles
Landscapes
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
- Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)
Description
本発明はポリプロピレン系樹脂予備発泡粒子の
製造法に関し、さらに気泡径の大きい（気泡数の
少ない粒子と気泡径の小さい（気泡数の多い）粒
子とが混在するポリプロピレン系樹脂予備発泡粒
子を製造する方法に関する。
本出願人は予備発泡粒子を得る方法をすでに提
案している（特公昭56−1344号）。この方法で
は、揮発性発泡剤を含有する重合体粒子を密閉容
器内で水に分散させ容器内の圧力を該発泡剤の蒸
気圧或はそれ以上の圧力に保持しながら該重合体
の軟化温度以上に加熱した後、容器内の水面下の
一端を開放し、重合体粒子と水とを同時に容器内
よりも低圧の雰囲気に放出することにより予備発
泡粒子が得られるものである。この予備発泡粒子
は高発泡で気泡径が小さい（気泡数が多い）画期
的なものであり、この予備発泡粒子を用いて得ら
れた発泡成型体を例えば包装材等として用いた場
合表面保護性に優れており有用であるが、柔軟性
が小さく（腰が弱く）破断し易いという若干の問
題点があつた。
本発明は上記予備発泡粒子をさらに改良したポ
リプロピレン系樹脂予備発泡粒子の製造法を提供
することを目的とするものであつて、本発明者ら
は上記の点について鋭意研究した結果、表面保護
性に優れ、柔軟性が大きい（腰が強い）発泡成型
体を与える気泡径の大きい粒子と気泡径の小さい
粒子とが混在するポリプロピレン系樹脂予備発泡
粒子の製造法の開発に成功し、本発明を完成する
に至つた。
すなわち、本発明はプロピレン系重合体粒子に
揮発性発泡剤を含有させる工程、密閉容器内でプ
ロピレン系重合体粒子を分散媒に分散させ加熱す
る工程および容器の一端を開放し、上記重合体粒
子と分散媒とを同時に容器内より低圧の雰囲気に
放出する工程よりなるポリプロピレン系樹脂予備
発泡粒子の製造法において、前記放出工程が、容
器内の圧力を揮発性発泡剤の蒸気圧以上に保持し
ながら放出する工程Ａと容器内の圧力を揮発性発
泡剤の蒸気圧未満に保持しながら放出する工程Ｂ
とよりなることを特徴とするポリプロピレン系樹
脂予備発泡粒子の製造法を要旨とするものであ
る。
本発明において用いられるプロピレン系重合体
としては架橋したもの無架橋のもののいずれでも
よいが無架橋のものが有益である。プロピレン系
重合体としてはエチレン―プロピレンランダム共
重合体、エチレン―プロピレンブロツク共重合
体、プロピレン単独重合体等等が挙げられるが、
特にエチレン―プロピレンランダム共重合体が好
ましい。
本発明に用いる揮発性発泡剤としては、例えば
プロパン、ブタン、ペンタン、ヘキサン、ヘプタ
ン等で例示される脂肪族炭化水素類、シクロブタ
ン、シクロペンタン等で例示される環式脂肪族炭
化水素類及びトリクロロフロロメタン、ジクロロ
ジフロロメタン、ジクロロテトラフロロエタン、
メチルクロライド、エチルクロライド、メチレン
クロライド等で例示されるハロゲン化炭化水素類
が使用される。この発泡剤の添加量は発泡剤の種
類および所望する発泡の程度によつて異なるが通
常10〜40重量部である。
本発明において発泡剤をプロピレン系重合体粒
子に含有させる時期は特に限定されない。従つて
予めプロピレン系重合体粒子に発泡剤を含有させ
ておき、この発泡剤を含有した重合体粒子を密閉
容器内に入れて該密閉容器内で分散媒に分散させ
てもよく、或いは重合体粒子と発泡剤を密閉容器
内に入れて該密閉容器内でそれらを分散媒に分散
させつつ重合体粒子に発泡剤を含有させてもよ
い。または密閉容器内で前記粒子をそれが軟化す
る温度以上の温度に加熱する過程において或いは
加熱した後において発泡剤を密閉容器内に入れて
前記粒子と発泡剤を分散させつつ前記粒子に発泡
剤を含有させてもよい。尚、前記粒子に発泡剤を
含有させるときの温度は任意であり、特に制限は
ないが、重合体粒子および揮発性発泡剤を分散媒
に分散させつつ重合体粒子が軟化する温度以上に
加熱した場合短時間で行なうことができるので特
に好ましい。
本発明では、プロピレン系重合体粒子と揮発性
発泡剤を別々に或いは揮発性発泡剤を重合体粒子
に含有させた後分散媒に分散させるが、このとき
要すれば分散剤、例えば微粒状の酸化アルミニウ
ムおよび酸化チタン、塩基性炭酸マグネシウム、
塩基性炭酸亜鉛、炭酸カルシウム等を用いること
ができる。この分散剤の添加量は通常重合体100
重量部に対し0.01〜10重量部である。また分散媒
は重合体粒子を溶解させない溶媒であればよく、
例えば水、エチレングリコール、グリセリン、メ
タノール、エタノール等のうちの１種又はそれら
の２種以上の混合物が例示されるが通常は水が好
ましい。
本発明では容器の一端を開放する前の容器内の
温度および圧力は特に限定されないが、温度は重
合体粒子の熱変形温度以上、通常は重合体粒子が
軟化する温度以上の温度、例えば90〜170℃に保
持され、圧力は揮発性発泡剤の蒸気圧付近以上の
圧力に保持される。
本発明において、容器の一端を開放してプロピ
レン系重合体粒子と水とを同時に容器内より低圧
の雰囲気に放出する工程は、放出時の容器内の圧
力を異ならせた工程Ａおよび工程Ｂよりなる。工
程Ａでは容器内の圧力は揮発性発泡剤の蒸気圧以
上に保持され、工程Ｂでは、揮発性発泡剤の蒸気
圧未満に保持される。工程Ａの容器内の圧力は通
常は容器の耐圧性を考慮して発泡剤の蒸気圧以上
40Kg／cm2（Ｇ）の圧力範囲に保持され、工程Ｂで
は、圧力が低過ぎると容器内で重合体粒子が融着
したり、発泡倍率が低下する傾向があるため発泡
剤の蒸気圧をPoとしたとき、通常は0.7Po以上蒸
気圧未満の圧力に保持される。工程ＡまたはＢ
は、それぞれの工程によつて得られる予備発泡粒
子量が全予備発泡粒子量の1/3以上2/3未満となる
ように行なうことが好ましい。工程Ａにより得ら
れる予備発泡粒子の量が1/3未満の場合には予備
発泡粒子を用いて得られる発泡成型体の表面保護
性が低下する傾向があり、また工程Ｂにより得ら
れる予備発泡粒子の量が1/3未満の場合には発泡
成型体の柔軟性が小さく、曲げ等により破断し易
い傾向がある。尚、工程Ａおよび工程Ｂはどちら
を先に行なつてもよく、また両者を交互に繰返し
行なつてもよい。本発明において揮発性発泡剤の
蒸気圧とは、発泡剤を重合体粒子に含有させた状
態で且つ該粒子が分散媒に分散された系における
蒸気圧を示すものであり、発泡剤が単独で存在す
る場合の蒸気圧とは必ずしも一致しない。すなわ
ち、発泡剤と粒子との親和性の程度、含有量およ
び発泡剤の種類の組合せ等によつて異なり一義的
に定めることはできない。
本発明において重合体粒子と分散媒を放出する
雰囲気は通常大気下が選ばれる。
本発明により得られる予備発泡粒子は気泡径が
大きいものと小さいもの（気泡数が多いものと少
ないもの）が混在するものである。すなわち、工
程Ａにより得られる予備発泡粒子は気泡径が小さ
く、通常250個／mm2以上の気泡数を有し、工程Ｂ
により得られる予備発泡粒子は気泡径が大きく、
通常250個／mm2未満の気泡数を有する。
本発明により得られる予備発泡粒子は通常発泡
成型体を得るために用いられる。この場合、成型
に先立つて予備発泡粒子は常温常圧下所定時間熟
成された後窒素、空気等の無機ガスまたは無機ガ
スと揮発性発泡剤との混合ガスにより所定圧力、
所定時間加圧熟成される。このように粒子内に内
圧を付与された予備発泡粒子を成型用金型に充填
し、２〜５Kg／cm2（Ｇ）の水蒸気を用いて加熱発
泡し、型通りの発泡成型体を得ることができる。
上記のようにして得られる発泡成型体は、例え
ば包装材、緩衝材、建築資材、車輌部材、断熱
材、浮揚材、食品容器等に用いることができる。
以上説明したように、本発明によれば、予備発
泡時の容器内の圧力を異ならせることにより、気
泡径の大きい粒子と小さい粒子とが混在するポリ
プロピレン系樹脂予備発泡粒子を得ることがで
き、この予備発泡粒子を用いて得られる発泡成型
体は柔軟性が大きく、かつ表面保護性が良好なも
のである。
以下、実施例および比較例を掲げて本発明をさ
らに詳細に説明する。
実施例１〜５および比較例１〜３
密閉容器中に、第１表に示すエチレン―プロピ
レン共重合体粒子、水、ジクロロジフロロメタン
を示された量注加し、撹拌下、140℃に昇温し、
0.5時間保持した後、容器内の圧力を工程Ａ、工
程Ｂの順でそれぞれ第１表に示す圧力に保持しな
がら容器の一端を開放し、重合体粒子と水とを同
時に大気下へ放出し乾燥して第１表に示す見掛け
発泡倍率および気泡数を有する予備発泡粒子を得
た。尚、工程Ａで得られた予備発泡粒子量の全体
に対する比を第１表に併せて示す。
また気泡数の測定は切断面を顕微鏡にて観察す
ることにより行なつた。
The present invention relates to a method for producing pre-expanded polypropylene resin particles, and further relates to a method for producing pre-expanded polypropylene resin particles in which particles with large cell diameters (with a small number of cells) and particles with small cell diameters (with a large number of cells) coexist. Regarding the method: The applicant has already proposed a method for obtaining pre-expanded particles (Japanese Patent Publication No. 56-1344). In this method, polymer particles containing a volatile blowing agent are dispersed in water in a closed container. After heating the container to a temperature higher than the softening temperature of the polymer while maintaining the pressure in the container at the vapor pressure of the blowing agent or higher, one end of the container below the water surface is opened, and the polymer particles and water are heated. At the same time, pre-expanded particles can be obtained by releasing these into an atmosphere with a lower pressure than the inside of the container.These pre-expanded particles are highly foamed and have a small cell diameter (large number of bubbles), which is revolutionary. When the foamed molded product obtained using these pre-expanded particles is used as a packaging material, for example, it has excellent surface protection properties and is useful, but it has some drawbacks such as low flexibility (weak stiffness) and easy breakage. There was a problem.The purpose of the present invention is to provide a method for producing pre-expanded polypropylene resin particles that further improves the above-mentioned pre-expanded particles, and the present inventors have conducted extensive research on the above-mentioned points. As a result, we developed a method for producing pre-expanded polypropylene resin particles that contain a mixture of particles with large and small cell diameters that provide excellent surface protection and a highly flexible (strong) foam molded product. The present invention was successful, and the present invention was completed.That is, the present invention includes a step of incorporating a volatile blowing agent into propylene-based polymer particles, and a step of dispersing the propylene-based polymer particles in a dispersion medium and heating them in a closed container. and a method for producing pre-expanded polypropylene resin particles comprising the steps of opening one end of the container and simultaneously releasing the polymer particles and dispersion medium from the inside of the container into a low-pressure atmosphere, wherein the releasing step Step A of releasing while maintaining the pressure in the container at or above the vapor pressure of the volatile blowing agent; and Step B of releasing while maintaining the pressure inside the container below the vapor pressure of the volatile blowing agent.
The gist of the present invention is a method for producing pre-expanded polypropylene resin particles, which is characterized by the following. The propylene polymer used in the present invention may be either crosslinked or non-crosslinked, but non-crosslinked ones are advantageous. Examples of propylene-based polymers include ethylene-propylene random copolymers, ethylene-propylene block copolymers, propylene homopolymers, etc.
Particularly preferred is an ethylene-propylene random copolymer. Volatile blowing agents used in the present invention include, for example, aliphatic hydrocarbons such as propane, butane, pentane, hexane, heptane, etc., cycloaliphatic hydrocarbons such as cyclobutane, cyclopentane, etc., and trichloro Fluoromethane, dichlorodifluoromethane, dichlorotetrafluoroethane,
Halogenated hydrocarbons exemplified by methyl chloride, ethyl chloride, methylene chloride, etc. are used. The amount of the foaming agent added varies depending on the type of foaming agent and the desired degree of foaming, but is usually 10 to 40 parts by weight. In the present invention, the timing of incorporating the blowing agent into the propylene polymer particles is not particularly limited. Therefore, a blowing agent may be contained in the propylene polymer particles in advance, and the polymer particles containing the blowing agent may be placed in a closed container and dispersed in a dispersion medium within the closed container. The foaming agent may be incorporated into the polymer particles by placing the particles and the blowing agent in a closed container and dispersing them in a dispersion medium within the closed container. Alternatively, during the process of heating the particles in a closed container to a temperature higher than the temperature at which they soften, or after heating, a blowing agent is placed in the closed container and the blowing agent is applied to the particles while dispersing the particles and the blowing agent. It may be included. The temperature at which the blowing agent is contained in the particles is arbitrary and there is no particular restriction, but the polymer particles and volatile blowing agent may be dispersed in a dispersion medium and heated to a temperature higher than the temperature at which the polymer particles soften. This is particularly preferred since it can be carried out in a short time. In the present invention, propylene polymer particles and a volatile blowing agent are dispersed in a dispersion medium either separately or after the volatile blowing agent is incorporated into the polymer particles. Aluminum oxide and titanium oxide, basic magnesium carbonate,
Basic zinc carbonate, calcium carbonate, etc. can be used. The amount of this dispersant added is usually 100% of the polymer.
It is 0.01 to 10 parts by weight. Further, the dispersion medium may be any solvent that does not dissolve the polymer particles.
Examples include water, ethylene glycol, glycerin, methanol, ethanol, etc., or a mixture of two or more thereof, but water is usually preferred. In the present invention, the temperature and pressure inside the container before opening one end of the container are not particularly limited, but the temperature is higher than the thermal deformation temperature of the polymer particles, usually higher than the temperature at which the polymer particles soften, for example 90 to The temperature is maintained at 170°C, and the pressure is maintained at around or above the vapor pressure of the volatile blowing agent. In the present invention, the step of opening one end of the container and simultaneously releasing the propylene polymer particles and water into a lower pressure atmosphere from the inside of the container is different from the steps A and B in which the pressure inside the container at the time of release is different. Become. In step A, the pressure within the container is maintained above the vapor pressure of the volatile blowing agent, and in step B, it is maintained below the vapor pressure of the volatile blowing agent. The pressure inside the container in process A is usually higher than the vapor pressure of the blowing agent, taking into consideration the pressure resistance of the container.
The pressure is maintained at a pressure range of 40Kg/cm 2 (G), and in step B, the vapor pressure of the blowing agent is lowered because if the pressure is too low, the polymer particles tend to fuse in the container and the expansion ratio decreases. When Po is used, the pressure is usually maintained at 0.7 Po or more and less than vapor pressure. Process A or B
It is preferable that the steps are carried out so that the amount of pre-expanded particles obtained in each step is 1/3 or more and less than 2/3 of the total amount of pre-expanded particles. If the amount of pre-expanded particles obtained in step A is less than 1/3, the surface protection property of the foam molded product obtained using the pre-expanded particles tends to decrease, and the pre-expanded particles obtained in step B If the amount is less than 1/3, the foamed molded product has low flexibility and tends to be easily broken by bending or the like. Note that either step A or step B may be performed first, or both may be performed alternately and repeatedly. In the present invention, the vapor pressure of a volatile blowing agent refers to the vapor pressure in a system in which the blowing agent is contained in polymer particles and the particles are dispersed in a dispersion medium. It does not necessarily correspond to the vapor pressure when it exists. That is, it varies depending on the degree of affinity between the blowing agent and particles, the content, the combination of types of blowing agents, etc., and cannot be unambiguously determined. In the present invention, the atmosphere in which the polymer particles and dispersion medium are released is normally selected to be atmospheric air. The pre-expanded particles obtained by the present invention are a mixture of particles with large and small cell diameters (those with a large number of cells and those with a small number of cells). That is, the pre-expanded particles obtained in step A have a small cell diameter and usually have a number of cells of 250 cells/mm 2 or more, and the pre-expanded particles obtained in step B
The pre-expanded particles obtained by
Usually has a cell count of less than 250/ mm2 . The pre-expanded particles obtained by the present invention are usually used to obtain foamed molded articles. In this case, prior to molding, the pre-expanded particles are aged at room temperature and pressure for a predetermined time, and then heated to a predetermined pressure using an inorganic gas such as nitrogen or air, or a mixed gas of an inorganic gas and a volatile blowing agent.
Matured under pressure for a predetermined period of time. The pre-expanded particles, to which internal pressure has been applied in this way, are filled into a mold, and heated and foamed using 2 to 5 kg/cm 2 (G) of water vapor to obtain a foam molded product according to the shape. I can do it. The foam molded product obtained as described above can be used, for example, in packaging materials, cushioning materials, construction materials, vehicle components, heat insulating materials, flotation materials, food containers, and the like. As explained above, according to the present invention, by varying the pressure inside the container during pre-foaming, it is possible to obtain pre-expanded polypropylene resin particles in which particles with large and small cell diameters coexist. The foamed molded product obtained using these pre-expanded particles has high flexibility and good surface protection properties. Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples. Examples 1 to 5 and Comparative Examples 1 to 3 The ethylene-propylene copolymer particles shown in Table 1, water, and dichlorodifluoromethane were added in the indicated amounts into a closed container, and the mixture was heated to 140°C while stirring. The temperature rises,
After holding for 0.5 hours, one end of the container was opened while maintaining the pressure in the container at the pressure shown in Table 1 in the order of Step A and Step B, and the polymer particles and water were released into the atmosphere at the same time. After drying, pre-expanded particles having the apparent expansion ratio and number of cells shown in Table 1 were obtained. The ratio of the amount of pre-expanded particles obtained in step A to the total amount is also shown in Table 1. The number of bubbles was measured by observing the cut surface with a microscope.
【表】【table】
【表】
次いで得られた予備発泡粒子を常温、常圧にて
50時間放置後、20℃、２Kg／cm2（Ｇ）の空気にて
50時間加圧熟成し、しかる後成型用金型に充填
し、水蒸気圧2.5Kg／cm2（Ｇ）にて加熱膨張させ
て型通りの発泡成型体を得た。この発泡成型体の
表面保護性および柔軟性を測定した。結果を第２
表に示す。[Table] Next, the obtained pre-expanded particles were heated at room temperature and pressure.
After being left for 50 hours, in air at 20℃ and 2Kg/cm 2 (G)
The mixture was aged under pressure for 50 hours, then filled into a mold, and heated and expanded at a water vapor pressure of 2.5 Kg/cm 2 (G) to obtain a foamed molded product conforming to the mold. The surface protection properties and flexibility of this foam molded product were measured. Second result
Shown in the table.
【表】【table】
Claims (1)
有させる工程、密閉容器内でプロピレン系重合体
粒子を分散媒に分散させ加熱する工程および容器
の一端を開放し、上記重合体粒子と分散媒とを同
時に容器内より低圧の雰囲気に放出する工程より
なるポリプロピレン系樹脂予備発泡粒子の製造法
において、前記放出工程が、容器内の圧力を揮発
性発泡剤の蒸気圧以上に保持しながら放出する工
程Ａと容器内の圧力を揮発性発泡剤の蒸気圧未満
に保持しながら放出する工程Ｂとよりなることを
特徴とするポリプロピレン系樹脂予備発泡粒子の
製造法。 ２ 前記工程ＡまたはＢで得られる予備発泡粒子
の量の全予備発泡粒子量に対する割合が1/3以
上、2/3未満である特許請求の範囲第１項記載の
ポリプロピレン系樹脂予備発泡粒子の製造法。[Claims] 1. A step of incorporating a volatile blowing agent into propylene polymer particles, a step of dispersing the propylene polymer particles in a dispersion medium and heating them in a closed container, and opening one end of the container to In a method for producing pre-expanded polypropylene resin particles, which comprises a step of simultaneously releasing the combined particles and the dispersion medium into an atmosphere at a lower pressure from inside the container, the releasing step increases the pressure inside the container to a level higher than the vapor pressure of the volatile blowing agent. A method for producing pre-expanded polypropylene resin particles, which comprises a step A in which the particles are discharged while being maintained, and a step B in which the pressure in the container is maintained at less than the vapor pressure of a volatile blowing agent. 2. Pre-expanded polypropylene resin particles according to claim 1, wherein the ratio of the amount of pre-expanded particles obtained in step A or B to the total amount of pre-expanded particles is 1/3 or more and less than 2/3. Manufacturing method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56175990A JPS5876234A (en) | 1981-11-02 | 1981-11-02 | Manufacture of prefoamed particle |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56175990A JPS5876234A (en) | 1981-11-02 | 1981-11-02 | Manufacture of prefoamed particle |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5876234A JPS5876234A (en) | 1983-05-09 |
| JPS6233254B2 true JPS6233254B2 (en) | 1987-07-20 |
Family
ID=16005767
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP56175990A Granted JPS5876234A (en) | 1981-11-02 | 1981-11-02 | Manufacture of prefoamed particle |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5876234A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH03275738A (en) * | 1990-03-19 | 1991-12-06 | Arco Chem Technol Inc | Foaming method for polymer particles by co2 |
-
1981
- 1981-11-02 JP JP56175990A patent/JPS5876234A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5876234A (en) | 1983-05-09 |
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