| 摘要 |
A WATER-CONTAINING POLYOLEFIN RESIN COMPOSITION CONTAINING A POLYOLEFIN RESIN AND A HYDROPHILIC POLYMER AND HAVING A WATER CONTENT OF 1 TO 50 % BY WEIGHT, WHICH IS SUITABLE FOR USE IN PREPARATION OF POLYOLEFIN RESIN PRE-EXPANDED PARTICLES, AND PRE-EXPANDED PARTICLES OF A POLYOLEFIN RESIN PREPARED BY PRE-EXPANDING THIS WATER CONTAINING POLYOLEFIN RESIN COMPOSITION AND HAVING A AN APPARENT EXPANSION RATIO OF 5 TO 60, A CLOSED CELL RATIO OF 80 TO 100 % AND AN AVERAGE CELL DIAMETER OF 50 TO 500 μM.THE PRE-EXPANDED PARTICLES CAN BE PREPARED WITHOUT USING A VOLATILE BLOWING AGENT BY DISPERSING RESIN PARTICLES MADE OF A POLYOLEFIN RESIN COMPOSITION CONTAINING A POLYOLEFIN RESIN AND A HYDROPHILIC POLYMER INTO AN AQUEOUS DISPERSION MEDIUM IN A CLOSED VESSEL TO FORM A DISPERSION, HEATING TO A TEMPERATURE OF NOT LOWER THAN THE SOFTENING POINT OF THE POLYOLEFIN RESIN TO GIVE WATER-CONTAINING RESIN PARTICLES HAVING A WATER CONTENT OF 1 TO 50 % BY WEIGHT, AND RELEASING THE AQUEOUS DISPERSION FROM THE CLOSED VESSEL INTO AN ATMOSPHERE OF LOWER PRESSURE THAN THE INNER PRESSURE OF THE CLOSED VESSEL, THEREBY EXPANDING THE WATER-CONTAINING RESIN PARTICLES.WHEN THE RELEASING OF THE DISPERSION FROM THE VESSEL IS CONDUCTED AFTER RAISING THE INNER PRESSURE TO 25 TO 75 KG/CM2G BY INTRODUCING NITROGEN GAS, AIR OR AN INORGANIC GAS COMPOSED OF THEM AS A MAIN COMPONENT INTO THE VESSEL, PRE-EXPANDED PARTICLES CAPABLE OF PROVIDING FOAMS HAVING GOOD PHYSICAL PROPERTIES AND A HIGH EXPANSION RATIO CAN BE OBTAINED.
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