JP2666061B2 - Pre-expansion method of polyolefin resin particles - Google Patents
Pre-expansion method of polyolefin resin particlesInfo
- Publication number
- JP2666061B2 JP2666061B2 JP62221289A JP22128987A JP2666061B2 JP 2666061 B2 JP2666061 B2 JP 2666061B2 JP 62221289 A JP62221289 A JP 62221289A JP 22128987 A JP22128987 A JP 22128987A JP 2666061 B2 JP2666061 B2 JP 2666061B2
- Authority
- JP
- Japan
- Prior art keywords
- resin particles
- container
- gas
- polyolefin
- ethylene
- 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
Classifications
-
- Y02P20/121—
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
【発明の詳細な説明】
〔産業上の利用分野〕
本発明はポリオレフィン系樹脂粒子の予備発泡方法に
関する。
〔従来の技術及び発明が解決しようとする問題点〕
ポリオレフィン系樹脂粒子等の重合体粒子を予備発泡
せしめる方法として種々の方法が提案されており、例え
ばポリオレフィン系樹脂粒子の予備発泡方法として、揮
発性発泡剤を含有するポリオレフィン系樹脂粒子を密閉
容器内で水に分散させ加圧下に該粒子の軟化点以上の温
度に加熱した後、窒素ガスにより容器内圧を一定に保持
しつつ、樹脂粒子と水とを容器内より低圧の雰囲気下に
放出して発泡させる方法が知られている（特公昭56−13
44号）。この方法によれば優れたポリオレフィン系樹脂
予備発泡粒子を得ることができるが、容器内の樹脂粒子
と水とを放出していくに従い、撹拌機の激しい回転によ
り樹脂粒子が水面より飛び出し、冷却されて水中へ飛び
込むといった現象が多発し、この結果として発泡時の樹
脂粒子の温度が設定温度より低くなり、得られる予備発
泡粒子の発泡倍率が低下する。また容器内空間中の温度
の低いガス（常温の窒素ガスを導入することにより、容
器内空間中に存在するガス（発泡剤と窒素ガスとの混合
物）の温度が低下する。）が容器内水位の低下ととも
に、撹拌機の激しい回転により水中に巻き込まれ易くな
り、容器内空間のガスを水中に巻き込むことによって水
温が更に低下して樹脂粒子の発泡温度が発泡の進行とと
もに低下し発泡倍率が低下する。更に容器内空間の容積
が大きくなるにつれ、容器内空間における揮発性発泡剤
の分圧が低下し、樹脂粒子内の発泡剤が抜け出すことに
も起因して予備発泡の進行に伴い発泡倍率が次第に低下
してしまうという問題があった。
ところでポリオレフィン系樹脂予備発泡粒子等の予備
発泡粒子を用いた型内成型法としては、予備発泡粒子に
内圧を付与した後に成型に供する方法、或いは予備発泡
粒子に特に内圧を付与することなく成型に供する方法が
挙げられる。内圧が高められた粒子を用いて成型を行っ
た場合、粒子の高発泡力により種々の発泡倍率の予備発
泡粒子が混在していても一応成型体となり得る。一方、
内圧付与の前処理を行わない粒子を用いて成型を行った
場合、特にポリオレフィン系樹脂予備発泡粒子では粒子
の低発泡力のために種々の発泡倍率の予備発泡粒子が混
在していると融着不良（主として低発泡倍率側にて）あ
るいは／かつ収縮（主として高発泡側にて）が生じてし
まい所望の成型品とはなり得ない。いずれの方法を採用
するにせよ、種々の発泡倍率の予備発泡粒子が混在した
まま成型を行うことは好ましくない。そこで従来は、内
圧付与の前処理を施さない粒子を用いて成型を行う場合
には、特に粒子を倍率によりふるい分けしなければなら
なかった。しかしながら、この様なふるい分けは、工程
上非常に複雑であり、改善が望まれていた。
一方、容器内に揮発性発泡剤を導入しつつ樹脂粒子の
放出を行うことにより容器内空間における揮発性発泡剤
の分圧を一定に保持して得られる予備発泡粒子の発泡倍
率を略一定にする方法等も提案されている（特開昭59−
30836号）。しかしながら揮発性発泡剤を容器内に導入
することによって容器内空間における揮発性発泡剤の分
圧を発泡開始から終了までの間一定に保持するためには
多量の揮発性発泡剤を必要とする。また揮発性発泡剤と
して高価であるが不燃性であることからフロンが広く用
いられている（特開昭59−30836号中の実施例でも用い
られている。）が、フロンガスを多量に使用すること
は、製造コスト面及びオゾン層破壊による環境問題の面
からいって非常に問題である。また、この方法は予備発
泡中に−30℃にも達する液状ジクロロジフロロメタン
（フロン）を圧入するものであるから、予備発泡中の容
器内水位の低下に伴い、低温発泡剤が多量に水中に巻き
込まれ、水温が低下したり、また水面より飛び出た樹脂
粒子が発泡剤により冷却されたりするため発泡温度を一
定に保ち難い。従って得られる予備発泡粒子の発泡の進
行に伴う発泡倍率低下は避けられないものであった。
これらの問題点に鑑み本出願人は、発泡剤を含有する
ポリオレフィン系樹脂粒子と分散媒とを容器内より低圧
の雰囲気下に放出して予備発泡せしめるのに際し、放出
量と略等しい量の加熱液体を容器内に供給しつつ放出を
行う方法を提案し先に出願したが（特願昭62−114026
号）、本発明者らは発泡倍率の低下という現象が主とし
て容器内容物の温度低下に起因することを見出し、更に
鋭意研究した結果、より効率よく予備発泡を行うことが
できる予備発泡方法を見出し本発明を完成するに至っ
た。
〔問題点を解決するための手段〕
本発明は樹脂粒子の温度低下による発泡倍率の低下を
防止し、発泡の開始から終了まで均一発泡倍率の予備発
泡粒子を効率よく得ることのできるポリオレフィン系樹
脂粒子の予備発泡方法を提供することを目的とするもの
である。
即ち本発明は耐圧容器中で、無機ガス発泡剤を含有す
るポリオレフィン系樹脂粒子を分散媒に分散させ、該樹
脂粒子の軟化点以上の温度に加熱した後、容器の一端を
開放し、樹脂粒子と分散媒とを容器内より低圧の雰囲気
下に放出するに際し、容器内に加熱無機ガスを導入しな
がら放出を行うことを特徴とするポリオレフィン系樹脂
粒子の予備発泡方法を要旨とするものである。
本発明に用いられるポリオレフィン系樹脂粒子として
は例えば直鎖状低密度ポリエチレン、低密度ポリエチレ
ン、高密度ポリエチレン、ポリプロピレン、ポリブチレ
ン、エチレン−プロピレンブロック共重合体、エチレン
−プロピレンランダム共重合体、エチレン成分を50％以
上含むエチレン−酢酸ビニル共重合体、エチレン−スチ
レン共重合体、エチレン−メチルメタクリレート共重合
体或いはエチレンと他のビニルモノマーとの共重合体等
の１種又は２種以上の混合物が挙げられる。
本発明においては、まず無機ガス発泡剤を含有するポ
リオレフィン系樹脂粒子を密閉容器内で分散媒に分散さ
せるが、ポリオレフィン系樹脂粒子と発泡剤を密閉容器
内で分散させて加熱、加圧することにより発泡剤を樹脂
粒子中に含有せしめることができる。
無機ガス発泡剤としては、窒素を主成分とする無機ガ
ス、二酸化炭素を主成分とする無機ガスの１種又は２種
以上の混合物が挙げられる。
分散媒としては水、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１種又は２種以上の混
合物が挙げられるが、通常は水が用いられる。また必要
に応じて酸化アルミニウム、酸化チタン、炭酸カルシウ
ム等の分散剤を用いることもできる。
次いで樹脂粒子を軟化点以上の温度に加熱した後、容
器の一端を開放して樹脂粒子と分散媒とを容器内より低
圧の雰囲気下（通常は大気圧下）へ放出するが、この際
容器内に加熱無機ガスを供給しつつ放出を行うことによ
り、容器内容物の温度低下が防止され、発泡開始から終
了までの間に亘って均一性の高い発泡倍率の予備発泡粒
子が得られる。
上記無機ガスとしては窒素を主成分とする無機ガス、
二酸化炭素を主成分とする無機ガスの１種又はそれらの
混合物が用いられる。また加熱無機ガスの温度は80℃以
上、発泡温度＋30℃以下とすることが好ましく、加熱無
機ガスは容器内圧力を20〜50kg/cm2（Ｇ）に維持できる
よう供給することが好ましい。加熱無機ガスの供給方法
としては、ボンベ又はコンプレッサーより供給される無
機ガスを熱交換機を通過せしめて加熱した後、パイプラ
インによって発揮槽へ供給する方法が挙げられる。
本発明方法によって得られる予備発泡粒子は成型用型
内に充填して加熱発泡せしめる所謂ビーズ成型に供され
るが、本発明によって得られる予備発泡粒子は発泡倍率
の均一性が高いので、発泡能のバラツキが少なく、一定
の条件で成型した場合に全ての粒子が同じように発泡
し、未発泡のものや、発泡後に収縮を生じるもの等が存
在することがないから、内圧付与の前処理せずに成型を
行う場合に非常に有用である。
また、本発明によって得られる予備発泡粒子は発泡倍
率の均一性が高いため、従来の如く成型に際して予備発
泡粒子を倍率によりふるい分けする手間を省くことがで
きる。
〔実施例〕
以下、実施例を挙げて本発明を更に詳細に説明する。
実施例１〜４及び比較例１
第１表に示すポリオレフィン系樹脂粒子と発泡剤及び
微粒状の酸化アルミニウム（500g）を、1m3の密閉容器
内で水500に分散させ、同表に示す温度に加熱して保
持した後、同温度にて第１表に示す圧力の加熱無機ガス
を容器内に供給して容器内をその温度に保持しながら容
器内の樹脂粒子と水とを大気圧下に第１表に示す時間で
放出して予備発泡を行った。また第２表に発泡開始後か
ら終了までの時間を４等分して予備発泡粒子をそれぞれ
サンプリングし、見掛け発泡倍率を測定した結果を示し
た。得られた予備発泡粒子を48時間大気圧下に放置して
熟成した後、内圧付与の前処理を施すことなく成型用金
型に充填して第２表に示す圧力の蒸気で加熱して成型し
た。得られた成型体の性状を第２表にあわせて示す。
比較例２〜４
第１表に示すポリオレフィン系樹脂粒子と発泡剤及び
微粒状の酸化アルミニウム（200g）を、400の密閉容
器内で水200に分散させた以外は、第１表に従い上記
実施例と同様の操作を行って予備発泡粒子を得、その
後、実施例と同条件にて成型を行った。結果を第２表に
あわせて示す。
として評価した。
〔発明の効果〕
本発明方法は、発泡剤を含有するポリオレフィン系樹
脂粒子を容器内より低圧の雰囲気下に放出して発泡せし
めるのに際し、容器内に加熱無機ガスを供給しながら放
出する方法を採用したため、樹脂粒子の温度低下をきた
すことがないから、温度低下に起因する発泡倍率低下を
きたす虞れもなく、発泡開始から終了までの間に亘って
発泡倍率を略一定に保持でき、均一性の高い発泡倍率の
予備発泡粒子を得ることができる。また本発明の方法で
は容器内に加熱液体を供給しながら発泡を行う方法に比
べて短時間で発泡を終了することができ、また加熱した
液体等を貯留しておくためのタンク等の設備も不要であ
り、しかも加熱エネルギーが液体に比べて少なくてすむ
利点がある。
更に本発明方法によれば、発泡剤として例え、フロン
ガスの如き問題の多いものを用いたとしても、従来法と
比較して多量に使用する必要がないから製造コストが高
くついたり、大きな環境問題を引き起こす等の虞れはな
い。しかも本発明方法により得られる予備発泡粒子は発
泡倍率によるふるい分けをせずとも発泡倍率の均一性が
高く、発泡能のバラツキがないから、内圧付与を行った
後に成型しても、特に内圧付与の前処理を行わずに成型
しても融着不良や収縮を生じる虞れがない。また内圧付
与工程を省略した場合には成型体製造工程の簡略化を図
ることができるとともに製造コストの低下をも図ること
ができる等の種々の効果を有するものである。The present invention relates to a method for prefoaming polyolefin resin particles. [Problems to be Solved by the Prior Art and the Invention] Various methods have been proposed as a method for pre-expanding polymer particles such as polyolefin-based resin particles. After the polyolefin-based resin particles containing a water-soluble blowing agent are dispersed in water in a closed container and heated to a temperature equal to or higher than the softening point of the particles under pressure, the resin particles and the resin particles are kept at a constant pressure with nitrogen gas. A method is known in which water and water are released from a container under a low-pressure atmosphere and foamed (JP-B-56-13).
No. 44). According to this method, excellent polyolefin-based resin pre-expanded particles can be obtained, but as the resin particles and water in the container are discharged, the resin particles jump out of the water surface due to vigorous rotation of the stirrer and are cooled. As a result, the temperature of the resin particles during foaming becomes lower than the set temperature, and the foaming ratio of the obtained pre-foamed particles decreases. In addition, the low-temperature gas in the space inside the container (the temperature of the gas (mixture of the foaming agent and the nitrogen gas) existing in the space inside the container is reduced by introducing nitrogen gas at normal temperature) is the water level in the container. As the stirrer violently rotates, it becomes easy to get caught in water, and the gas inside the container is caught in the water, which further lowers the water temperature and reduces the foaming temperature of the resin particles as the foaming progresses, lowering the foaming ratio. I do. Furthermore, as the volume of the container space increases, the partial pressure of the volatile foaming agent in the container space decreases, and the foaming ratio gradually increases with the progress of prefoaming due to the foaming agent in the resin particles coming out. There was a problem that it would decrease. By the way, as an in-mold molding method using pre-expanded particles such as polyolefin-based resin pre-expanded particles, a method in which the internal pressure is applied to the pre-expanded particles and then subjected to molding, or molding without applying an internal pressure to the pre-expanded particles in particular. Method to be provided. When molding is performed using particles having an increased internal pressure, a molded article can be formed even if pre-expanded particles having various expansion ratios are mixed due to the high foaming power of the particles. on the other hand,
When molding is performed using particles that have not been subjected to internal pressure pretreatment, especially in the case of polyolefin-based resin pre-expanded particles, the pre-expanded particles of various expansion ratios are mixed due to the low expansion force of the particles and are fused. A defect (mainly on the low expansion ratio side) or / and shrinkage (mainly on the high expansion side) occurs, and a desired molded product cannot be obtained. Regardless of which method is employed, it is not preferable to carry out molding with pre-expanded particles having various expansion ratios mixed. Therefore, conventionally, when molding is performed using particles that have not been subjected to a pretreatment for applying an internal pressure, the particles have to be sieved particularly according to the magnification. However, such sieving is very complicated in the process, and improvement has been desired. On the other hand, the expansion ratio of the pre-expanded particles obtained by maintaining the partial pressure of the volatile foaming agent in the container space constant by performing the release of the resin particles while introducing the volatile foaming agent into the container is substantially constant. A method has been proposed (Japanese Unexamined Patent Publication No.
30836). However, a large amount of the volatile foaming agent is required in order to keep the partial pressure of the volatile foaming agent in the container space constant from the start to the end of foaming by introducing the volatile foaming agent into the container. CFCs are widely used because they are expensive but nonflammable as a volatile foaming agent (also used in Examples in JP-A-59-30836), but use a large amount of CFC gas. This is very problematic in terms of manufacturing costs and environmental problems due to ozone layer depletion. Also, since this method involves injecting liquid dichlorodifluoromethane (CFC) that reaches -30 ° C during prefoaming, a large amount of low-temperature blowing agent is added to the water as the water level in the container decreases during prefoaming. It is difficult to keep the foaming temperature constant because the water temperature decreases and the resin particles that have protruded from the water surface are cooled by the foaming agent. Therefore, a decrease in the expansion ratio due to the progress of the expansion of the obtained pre-expanded particles was inevitable. In view of these problems, the applicant of the present application discloses that when the polyolefin-based resin particles containing a foaming agent and the dispersion medium are preliminarily foamed by being released from the inside of the container under a low-pressure atmosphere, the amount of heating is substantially the same as the amount of heating. A method for discharging a liquid while supplying the liquid into the container was proposed and filed earlier (Japanese Patent Application No. 62-114026).
No.), the present inventors have found that the phenomenon of reduction in the expansion ratio is mainly caused by a decrease in the temperature of the contents of the container, and as a result of further intensive research, they have found a pre-expansion method that can perform pre-expansion more efficiently. The present invention has been completed. [Means for Solving the Problems] The present invention prevents a decrease in the expansion ratio due to a decrease in the temperature of the resin particles, and makes it possible to efficiently obtain pre-expanded particles having a uniform expansion ratio from the start to the end of expansion. It is an object to provide a method for pre-expanding particles. That is, the present invention, in a pressure vessel, after dispersing the polyolefin resin particles containing an inorganic gas blowing agent in a dispersion medium, heated to a temperature above the softening point of the resin particles, then open one end of the container, the resin particles And a method for prefoaming polyolefin-based resin particles, characterized in that, when releasing the dispersion medium and the dispersion medium into a lower-pressure atmosphere than in the container, the release is performed while introducing a heated inorganic gas into the container. . Examples of the polyolefin resin particles used in the present invention include linear low-density polyethylene, low-density polyethylene, high-density polyethylene, polypropylene, polybutylene, an ethylene-propylene block copolymer, an ethylene-propylene random copolymer, and an ethylene component. One or a mixture of two or more of ethylene-vinyl acetate copolymer, ethylene-styrene copolymer, ethylene-methyl methacrylate copolymer or a copolymer of ethylene and another vinyl monomer containing 50% or more. Can be In the present invention, first, the polyolefin-based resin particles containing an inorganic gas foaming agent are dispersed in a dispersion medium in a closed container, but the polyolefin-based resin particles and the foaming agent are dispersed in a closed container, and heated and pressurized. A foaming agent can be contained in the resin particles. Examples of the inorganic gas blowing agent include one or a mixture of two or more of an inorganic gas containing nitrogen as a main component and an inorganic gas containing carbon dioxide as a main component. Examples of the dispersion medium include one or a mixture of two or more of water, ethylene glycol, glycerin, methanol, and ethanol, but water is usually used. If necessary, a dispersant such as aluminum oxide, titanium oxide, or calcium carbonate can be used. Next, after heating the resin particles to a temperature equal to or higher than the softening point, one end of the container is opened to release the resin particles and the dispersion medium into a lower-pressure atmosphere (usually under atmospheric pressure) than the inside of the container. By performing the release while supplying the heated inorganic gas into the inside, the temperature of the contents of the container is prevented from lowering, and pre-expanded particles having a high expansion ratio with high uniformity from the start to the end of the expansion can be obtained. As the inorganic gas, an inorganic gas containing nitrogen as a main component,
One type of inorganic gas containing carbon dioxide as a main component or a mixture thereof is used. The temperature of the heated inorganic gas is preferably 80 ° C. or more and the foaming temperature + 30 ° C. or less, and the heated inorganic gas is preferably supplied such that the pressure in the container can be maintained at 20 to 50 kg / cm 2 (G). Examples of the method for supplying the heated inorganic gas include a method in which an inorganic gas supplied from a cylinder or a compressor is heated by passing it through a heat exchanger, and then supplied to a display tank via a pipeline. The pre-expanded particles obtained by the method of the present invention are subjected to so-called bead molding in which the pre-expanded particles obtained by the method of the present invention are filled in a mold and heat-foamed. When molding under certain conditions, all particles foam in the same manner, and there is no unfoamed or shrinkage after foaming. It is very useful when molding without using. In addition, since the pre-expanded particles obtained by the present invention have a high degree of uniformity of the expansion ratio, it is possible to eliminate the trouble of sieving the pre-expanded particles at the time of molding as in the related art. EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. Examples 1 to 4 and Comparative Examples 1 blowing agent and polyolefin resin particles shown in Table 1 and finely divided aluminum oxide (500 g), was dispersed in water 500 in a sealed vessel 1 m 3, a temperature shown in the Table After heating and holding at a temperature, a heated inorganic gas having the pressure shown in Table 1 at the same temperature is supplied into the container, and while the inside of the container is maintained at that temperature, the resin particles and water in the container are brought under atmospheric pressure. Then, pre-foaming was carried out by releasing at the times shown in Table 1. Further, Table 2 shows the results obtained by sampling the pre-expanded particles by dividing the time from the start of foaming to the end thereof into four equal parts and measuring the apparent expansion ratio. The obtained pre-expanded particles were aged for 48 hours at atmospheric pressure, aged, filled in a molding die without pretreatment for applying an internal pressure, and heated with steam at a pressure shown in Table 2 to form a molded product. did. The properties of the obtained molded body are shown in Table 2. Comparative Examples 2 to 4 The above Examples according to Table 1 except that the polyolefin-based resin particles, the foaming agent, and the finely divided aluminum oxide (200 g) shown in Table 1 were dispersed in water 200 in a 400 sealed container. By performing the same operation as described above, pre-expanded particles were obtained. Thereafter, molding was performed under the same conditions as in the example. The results are shown in Table 2. Was evaluated. [Effects of the Invention] The method of the present invention is a method of releasing polyolefin-based resin particles containing a foaming agent under a low-pressure atmosphere from a container while supplying heated inorganic gas into the container. Since the adoption does not cause the temperature of the resin particles to decrease, there is no possibility of causing a decrease in the expansion ratio due to the temperature decrease, and the expansion ratio can be maintained substantially constant from the start to the end of the expansion, and the uniformity can be maintained. Pre-expanded particles having a high expansion ratio can be obtained. Further, in the method of the present invention, foaming can be completed in a shorter time than in a method in which foaming is performed while supplying a heated liquid into the container, and facilities such as a tank for storing the heated liquid and the like are also provided. There is an advantage that it is unnecessary and requires less heating energy than liquid. Further, according to the method of the present invention, even if a foaming agent such as chlorofluorocarbon gas is used, it is not necessary to use a large amount as compared with the conventional method. There is no fear of causing the above. Moreover, the pre-expanded particles obtained by the method of the present invention have high uniformity of the expansion ratio without sieving by the expansion ratio, and there is no variation in the expansion ability. Even if molding is performed without performing the pretreatment, there is no possibility that defective fusion or shrinkage will occur. Further, when the internal pressure applying step is omitted, there are various effects such as simplification of the molded body manufacturing step and reduction of the manufacturing cost.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 内藤 真人 神奈川県平塚市真土170―１ (56)参考文献 特開 昭59−30836（ＪＰ，Ａ) 特公 昭56−1344（ＪＰ，Ｂ２) ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masato Naito 170-1 Mado, Hiratsuka City, Kanagawa Prefecture (56) References JP-A-59-30836 (JP, A) JP-B-56-1344 (JP, B2)
Claims (1)
フィン系樹脂粒子を分散媒に分散させ、該樹脂粒子の軟
化点以上の温度に加熱した後、容器の一端を解放し、樹
脂粒子と分散媒とを容器内より低圧の雰囲気下に放出す
るに際し、容器内に加熱無機ガスを導入しながら放出を
行うことを特徴とするポリオレフィン系樹脂発泡粒子の
予備発泡方法。 ２．加熱無機ガスが窒素ガス及び／又は二酸化炭素ガス
を主成分とするガスである特許請求の範囲第１項記載の
ポリオレフィン系樹脂発泡粒子の予備発泡方法。 ３．加熱無機ガスにより容器内圧力を２〜50kg/cm
2（Ｇ）に保持して放出を行う特許請求の範囲第１項又
は第２項記載のポリオレフィン系樹脂発泡粒子の予備発
泡方法。 ４．加熱無機ガスの温度が80℃以上、発泡温度＋30℃以
下である特許請求の範囲第１項〜第３項のいずれかに記
載のポリオレフィン系樹脂発泡粒子の予備発泡方法。 ５．無機ガス発泡剤が、窒素を主成分とする無機ガス、
二酸化炭素を主成分とする無機ガスの１種又は２種以上
の混合物である特許請求の範囲第１項〜第４項のいずれ
かに記載のポリオレフィン系樹脂発泡粒子の予備発泡方
法。 ６．ポリオレフィン系樹脂粒子がポリエチレン、ポリプ
ロピレン、エチレン−プロピレンブロック共重合体、エ
チレン−プロピレンランダム共重合体、エチレン−酢酸
ビニル共重合体、エチレン−スチレン共重合体、エチレ
ン−メチルメタクリレート共重合体からなる群より選ば
れた少なくとも１種よりなる特許請求の範囲第１項〜第
５項のいずれかに記載のポリオレフィン系樹脂発泡粒子
の予備発泡方法。(57) [Claims] In a pressure-resistant container, polyolefin-based resin particles containing an inorganic gas blowing agent are dispersed in a dispersion medium, and after heating to a temperature equal to or higher than the softening point of the resin particles, one end of the container is released, and the resin particles and the dispersion medium Pre-foaming of expanded polyolefin resin particles, characterized in that, while releasing a heated inorganic gas into the container, the gas is discharged into the container under a low-pressure atmosphere. 2. 2. The method for prefoaming expanded polyolefin resin particles according to claim 1, wherein the heated inorganic gas is a gas containing nitrogen gas and / or carbon dioxide gas as a main component. 3. The pressure inside the container is increased by 2 to 50 kg / cm by heating inorganic gas.
3. The method for prefoaming expanded polyolefin-based resin particles according to claim 1 or 2, wherein the foamed polyolefin resin particles are released while being held at (G). 4. The method for prefoaming expanded polyolefin-based resin particles according to any one of claims 1 to 3, wherein the temperature of the heated inorganic gas is 80C or more and the foaming temperature + 30C or less. 5. An inorganic gas blowing agent, an inorganic gas containing nitrogen as a main component,
The method for prefoaming expanded polyolefin-based resin particles according to any one of claims 1 to 4, wherein the method is a mixture of one or more inorganic gases containing carbon dioxide as a main component. 6. Polyolefin-based resin particles are a group consisting of polyethylene, polypropylene, ethylene-propylene block copolymer, ethylene-propylene random copolymer, ethylene-vinyl acetate copolymer, ethylene-styrene copolymer, ethylene-methyl methacrylate copolymer The method for prefoaming expanded polyolefin resin particles according to any one of claims 1 to 5, comprising at least one selected from the group consisting of:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62221289A JP2666061B2 (en) | 1987-09-04 | 1987-09-04 | Pre-expansion method of polyolefin resin particles |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62221289A JP2666061B2 (en) | 1987-09-04 | 1987-09-04 | Pre-expansion method of polyolefin resin particles |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6465141A JPS6465141A (en) | 1989-03-10 |
| JP2666061B2 true JP2666061B2 (en) | 1997-10-22 |
Family
ID=16764451
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62221289A Expired - Fee Related JP2666061B2 (en) | 1987-09-04 | 1987-09-04 | Pre-expansion method of polyolefin resin particles |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2666061B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2874772B2 (en) * | 1989-11-24 | 1999-03-24 | 株式会社ジェイエスピー | Method for producing expanded polymer particles |
| KR101674610B1 (en) * | 2015-06-15 | 2016-11-09 | 롯데케미칼 주식회사 | Polymer foam particle and preparation method of the same |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS561344A (en) * | 1979-06-18 | 1981-01-09 | Nishimu Denshi Kogyo Kk | Controlling method for optimum wet-quantity in wet-type insulator stain measurement |
| JPS5930836A (en) * | 1982-08-13 | 1984-02-18 | Kanegafuchi Chem Ind Co Ltd | Method for preliminarily expanding polyolefin type resin particle |
-
1987
- 1987-09-04 JP JP62221289A patent/JP2666061B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6465141A (en) | 1989-03-10 |
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