Method and apparatus for manufacturing foam molded body

Patent metadata

Field	Value
Publication number	US-11207809-B2
Application number	US-201816050503-A
Country	US
Kind code	B2
Filing date	Jul 31, 2018
Priority date	Mar 15, 2016
Publication date	Dec 28, 2021
Grant date	Dec 28, 2021

Abstract

A producing method for producing a foam-molded product by using a plasticizing cylinder having, from an upstream side in the following order: a plasticization zone, a flow rate adjusting zone and a starvation zone, the producing method includes: plasticizing and melting a thermoplastic resin into a molten resin in the plasticization zone; adjusting a flow rate of the molten resin in the flow rate adjusting zone; allowing the molten resin to be in a starved state in the starvation zone; introducing a pressurized fluid containing the physical foaming agent having a fixed pressure into the starvation zone so as to retain the starvation zone at the fixed pressure; bringing the molten resin in the starved state in contact with the pressurized fluid in the starvation zone in a state in which the starvation zone is retained at the fixed pressure; and molding the molten resin into the foam-molded product.

First claim

What is claimed is:

1. A producing method for producing a foam-molded product by using a plasticizing cylinder, dividing into zones including, from an upstream side in the following order: a plasticization zone, a flow rate adjusting zone, and a starvation zone, and the plasticizing cylinder having an introducing port via which a physical foaming agent is introduced into the starvation zone, the producing method comprising:
plasticizing and melting a thermoplastic resin into a molten resin in the plasticization zone;
adjusting a flow rate of the molten resin in the flow rate adjusting zone;
allowing the molten resin, of which flow rate has been adjusted in the flow rate adjusting zone, to be in a starved state in the starvation zone;
introducing a pressurized fluid containing the physical foaming agent having a constant pressure into the starvation zone so as to retain the starvation zone at the constant pressure;
bringing the molten resin in the starved state in contact with the pressurized fluid containing the physical foaming agent having the constant pressure in the starvation zone in a state in which the starvation zone is retained at the constant pressure; and
molding the molten resin, having been brought in contact with the pressurized fluid containing the physical foaming agent, into the foam-molded product.

2. The producing method according to claim 1 , wherein the molten resin is pressurized with the pressurized fluid containing the physical foaming agent in the starvation zone.

3. The producing method according to claim 1 , wherein the starvation zone is maintained constantly at the constant pressure during production of the foam-molded product.

4. The producing method according to claim 1 , wherein an inner diameter of the introducing port is in a range of 20% to 100% of an inner diameter of the plasticizing cylinder.

5. The producing method according to claim 1 , wherein the introducing port is opened at all times.

6. The producing method according to claim 1 , wherein:
the plasticizing cylinder includes an introducing speed adjusting container connected to the introducing port;
the producing method further comprises supplying the pressurized fluid containing the physical foaming agent to the introducing speed adjusting container; and
the pressurized fluid containing the physical foaming agent having the constant pressure is introduced into the starvation zone from the introducing speed adjusting container.

7. The producing method according to claim 6 , wherein a volume of the introducing speed adjusting container is in a range of 5 mL to 10 L.

8. The producing method according to claim 1 , further comprising:
detecting expansion of the molten resin from the introducing port; and
stopping driving of the plasticizing cylinder in response to detecting the expansion of the molten resin from the introducing port.

9. The producing method according to claim 1 , wherein a chemical foaming agent is contained in the thermoplastic resin in an amount in a range of 0.1% by weight to 3% by weight.

10. The producing method according to claim 1 , wherein pressure reduction and compression of the molten resin are performed in the flow rate adjusting zone.

11. The producing method according to claim 10 , wherein the pressure reduction and the compression of the molten resin are repeated for a plurality of times.

12. The producing method according to claim 1 , wherein the flow rate of the molten resin is increased along a flowing direction of the molten resin in the flow rate adjusting zone.

13. The producing method according to claim 1 , wherein a pressure of the molten resin is decreased along a flowing direction of the molten resin in the flow rate adjusting zone.

14. A producing apparatus which produces a foam-molded product, the producing apparatus comprising:
a plasticizing cylinder having a plasticizing screw rotatably arranged in the plasticizing cylinder, the plasticizing cylinder including (i) a plasticization zone for plasticizing and melting a thermoplastic resin into a molten resin, (ii) a flow rate adjusting zone for adjusting a flow rate of the molten resin, and (iii) a starvation zone for allowing the molten resin to be in a starved state, and the plasticizing cylinder is formed with an introducing port that introduces a physical foaming agent into the starvation zone;
an introducing speed adjusting container connected to the introducing port; and
a physical foaming agent supplying mechanism connected to the introducing speed adjusting container, and the physical foaming agent supplying mechanism supplies the physical foaming agent to the plasticizing cylinder via the introducing speed adjusting container, wherein:
a pressurized fluid containing the physical foaming agent having a constant pressure is introduced into the starvation zone so as to retain the starvation zone at the constant pressure;
the molten resin in the starved state is brought in contact with the pressurized fluid containing the physical foaming agent having the constant pressure in the starvation zone in a state in which the starvation zone is retained at the constant pressure; and
the molten resin having been brought in contact with the pressurized fluid containing the physical foaming agent is molded into the foam-molded product.

15. The producing apparatus according to claim 14 , wherein an inner diameter of the introducing port is in a range of 20% to 100% of an inner diameter of the plasticizing cylinder; and
a volume of the introducing speed adjusting container is in a range of 5 mL to 10 L.

16. The producing apparatus according to claim 14 , wherein the introducing port is opened at all times.

17. The producing apparatus according to claim 14 , wherein the introducing speed adjusting container is provided with an expansion detecting mechanism which detects expansion of the molten resin from the introducing port.

18. The producing apparatus according to claim 14 , wherein:
the plasticizing cylinder further comprises a compression zone for compressing the molten resin, the compression zone being arranged on an upstream side of the flow rate adjusting zone; and
the plasticizing screw has a pressure reducing portion and a compressing portion which are positioned in the flow rate adjusting zone, the pressure reducing portion reducing a pressure of the molten resin and the compressing portion compressing the molten resin.

19. The producing apparatus according to claim 18 , wherein the plasticizing screw has a plurality of pairs of the pressure reducing portion and the compressing portion in the flow rate adjusting zone.

20. The producing apparatus according to claim 19 , wherein:
the pressure reducing portion and the compressing portion are arranged adjacently from the upstream side in this order;
a diameter of a shaft of the plasticizing screw in the pressure reducing portion is smaller than a maximum value of a diameter of the shaft of the plasticizing screw in the compression zone adjacently arranged on an upstream side of the pressure reducing portion or in the compressing portion; and
the diameter of the shaft of the plasticizing screw in the compressing portion is greater than a minimum value of the diameter of the shaft of the plasticizing screw in the pressure reducing portion adjacently arranged on an upstream side of the compressing portion.

21. The producing apparatus according to claim 14 , wherein the plasticizing screw has a screw flight which has a notch and which is positio

Assignees

• Maxell Ltd

Inventors

• Yusa Atsushi
• Yamamoto Satoshi
• Goto Hideto

Classifications

• B29C45/60

  Screws · CPC title

• B29K2067/003

  PET, i.e. poylethylene terephthalate · CPC title

• B29C48/0012

  combined with shaping by internal pressure generated in the material, e.g. foaming · CPC title

• B29C44/60

  Measuring, controlling or regulating · CPC title

• B29C48/29

  in liquid form · CPC title