Bulk-density measuring device for pre-expanded particles and method for manufacturing pre-expanded particles

Patent metadata

Field	Value
Publication number	US-2016229096-A1
Application number	US-201415029784-A
Country	US
Kind code	A1
Filing date	Apr 7, 2014
Priority date	Oct 18, 2013
Publication date	Aug 11, 2016
Grant date	—

Abstract

A bulk-density measuring device includes a first vessel in which contracted pre-expanded particles are swollen and recovered from contraction in a pressure-reduced state where a vessel internal pressure is lower than atmospheric pressure; a second vessel filled with the pre-expanded particles after being swollen in the first vessel in the pressure-reduced state where a vessel internal pressure is lower than the atmospheric pressure, and into which the pre-expanded particles of a constant volume are collected fractionally; a pressure-reducing unit that adjusts the vessel internal pressures of the first vessel and the second vessel to be lower than the atmospheric pressure; and a scale that measures a weight of the pre-expanded particles filled in the second vessel.

First claim

1 . A bulk-density measuring device comprising:
a first vessel in which contracted pre-expanded particles are swollen and recovered from contraction in a pressure-reduced state where a vessel internal pressure is lower than atmospheric pressure; a second vessel filled with the pre-expanded particles after being swollen in the first vessel in the pressure-reduced state where a vessel internal pressure is lower than the atmospheric pressure, and into which the pre-expanded particles of a constant volume are collected fractionally; a pressure-reducing unit that adjusts the vessel internal pressures of the first vessel and the second vessel to be lower than the atmospheric pressure; and a scale that measures a weight of the pre-expanded particles filled in the second vessel.

2 . The bulk-density measuring device according to claim 1 , further comprising, between the first vessel and the second vessel, a first vessel discharge valve that discharges the pre-expanded particles accommodated in the first vessel in a freely falling manner and filling the second vessel with the pre-expanded particles.

3 . The bulk-density measuring device according to claim 1 , further comprising a second vessel discharge valve that discharges the pre-expanded particles filled in the second vessel to the scale.

4 . The bulk-density measuring device according to claim 1 , further comprising a unit that makes the internal pressures of the first vessel and the second vessel different from each other.

5 . The bulk-density measuring device according to claim 1 , wherein the first vessel has a conical portion and an angle α of the conical portion is equal to or larger than 60° and equal to or smaller than 120°.

6 . The bulk-density measuring device according to claim 1 , wherein at least one valve for controlling the vessel internal pressure is arranged on a pipe connecting the first vessel and the pressure-reducing unit and/or a pipe connecting the second vessel and the pressure-reducing unit.

7 . The bulk-density measuring device according to claim 1 , wherein the second vessel comprises a forcible discharge unit that forcibly discharges the pre-expanded particles filled in the second vessel B.

8 . The bulk-density measuring device according to claim 1 , wherein the first vessel comprises a level switch that controls an accommodation amount of the pre-expanded particles to be accommodated.

9 . A method for measuring bulk density of pre-expanded particles, the method comprising:
a) collecting a part or all of the contracted pre-expanded particles and transporting the contracted pre-expanded particles to a first vessel; b) swelling the contracted pre-expanded particles to recover from contraction by making an internal pressure of the first vessel in a pressure-reduced state lower than atmospheric pressure; c) making an internal pressure of a second vessel in the pressure-reduced state lower than the atmospheric pressure; d) filling the second vessel with the pre-expanded particles after being swollen in the first vessel in the pressure-reduced state where the vessel internal pressure is lower than the atmospheric pressure by opening a valve between the first vessel and the second vessel and fractionally collecting the pre-expanded particles of a constant volume; and e) measuring a weight of the pre-expanded particles by a scale after the internal pressure of the second vessel is returned to the atmospheric pressure and the pre-expanded particles filled in the second vessel are discharged.

10 . The method for measuring the bulk density of the pre-expanded particles according to claim 9 , wherein in the step c), the internal pressure of the second vessel is set to be higher than the internal pressure of the first vessel.

11 . The method for measuring the bulk density of the pre-expanded particles according to claim 9 , wherein in the step c), the internal pressure of the second vessel is set to be lower than the internal pressure of the first vessel.

12 . The method for measuring the bulk density of the pre-expanded particles according to claim 9 , wherein in the step c), the internal pressures of the first vessel and the second vessel are set to be equivalent.

13 . The method for measuring the bulk density of the pre-expanded particles according to claim 9 , wherein the internal pressures of the first vessel and the second vessel are equal to or higher than 10×10 3 Pa and equal to or lower than 90×10 3 Pa.

14 . The method for measuring the bulk density of the pre-expanded particles according to claim 9 , wherein in the step a), a bulk volume of the contracted pre-expanded particles transported to the first vessel is equal to or higher than 20% and equal to or lower than 80% of an internal volume of the first vessel.

15 . The method for measuring the bulk density of the pre-expanded particles according to claim 9 , wherein
in the step d), the filling of the second vessel with the pre-expanded particles is performed in a freely falling manner, and in the step e), the discharging of the pre-expanded particles from the second vessel is performed at least using a forcible discharge unit.

16 . The method for measuring the bulk density of the pre-expanded particles according to claim 9 , wherein the pre-expanded particles are polyolefin resin pre-expanded particles.

17 . A method for manufacturing pre-expanded particles, the method comprising:
adjusting expanding conditions of the pre-expanded particles in a pre-expanding device by comparing a measurement result and target bulk density; and feeding back a result of the comparison to the pre-expanding device after bulk density of the pre-expanded particles is measured by the measuring method according to claim 9 .

18 . The method for manufacturing the pre-expanded particles according to claim 17 , wherein the pre-expanding device is a second-stage expanding machine.

19 . The method for manufacturing the pre-expanded particles according to claim 17 , wherein the pre-expanded particles are polyolefin resin pre-expanded particles having bulk density of equal to or higher than 8 g/L and lower than 30 g/L.

Assignees

• Kaneka Corp

Inventors

• Murakami Kyosuke
• Ochikoshi Shinobu
• Yoshida Toru

Classifications

• B29C44/3461

  Making or treating expandable particles · CPC title

• B29K2995/0063

  Density · CPC title

• B29K2023/06

  PE, i.e. polyethylene · CPC title

• B29C44/60 Primary

  Measuring, controlling or regulating · CPC title

• C08J2323/06

  Polyethene · CPC title