Manufacturing method and manufacturing device for foam molded article

Patent metadata

Field	Value
Publication number	US-11478969-B2
Application number	US-201916564640-A
Country	US
Kind code	B2
Filing date	Sep 9, 2019
Priority date	Mar 10, 2017
Publication date	Oct 25, 2022
Grant date	Oct 25, 2022

Abstract

A method for producing a foam-molded product uses a producing apparatus including a plasticizing cylinder. The plasticizing cylinder has a plasticization zone, a starvation zone, and an introducing port which is formed in the plasticizing cylinder and via which a physical foaming agent is introduced into the starvation zone. The method includes: plasticizing and melting a thermoplastic resin into a molten resin in the plasticization zone; introducing a pressurized fluid containing the physical foaming agent having a fixed pressure into the starvation zone; allowing the molten resin to be in the starved state in the starvation zone; bringing the molten resin in the starved state into contact with the pressurized fluid having the fixed pressure in the starvation zone; and molding the molten resin into the foam-molded product. At least one pressure boosting part is provided in the starvation zone.

First claim

What is claimed is:

1. A method for producing a foam-molded product by using a producing apparatus including a plasticizing cylinder provided with a plasticizing screw which is rotatable inside the plasticizing cylinder, wherein the plasticizing cylinder comprises: a plasticization zone in which a thermoplastic resin is plasticized and melt into a molten resin, a starvation zone in which the molten resin is allowed to be in a starved state, and a recompression zone in which the molten resin is compressed to increase pressure of the molten resin, wherein the plasticization zone, the starvation zone, and the recompression zone are arranged in this order from an upstream side in a flowing direction of the resin, and wherein the plasticizing cylinder further comprises an introducing port via which a physical foaming agent is introduced into the starvation zone, the method comprising:
plasticizing and melting the thermoplastic resin into the molten resin in the plasticization zone;
introducing a pressurized fluid containing the physical foaming agent having a fixed pressure into the starvation zone;
allowing the molten resin to be in the starved state in the starvation zone;
bringing the molten resin in the starved state into contact with the pressurized fluid having the fixed pressure in the starvation zone;
compressing the molten resin in the starved state that is in contact with the pressurized fluid to increase the pressure of the molten resin in the recompression zone; and
molding the pressure-increased molten resin into the foam-molded product,
wherein at least one pressure boosting part is provided in the starvation zone of the plasticizing cylinder.

2. The method for producing the foam-molded product according to claim 1 , wherein the pressure boosting part is formed of a part of the plasticizing screw; and
in the starvation zone, diameter of a shaft of the plasticizing screw is greater in the pressure boosting part than in a different part from the pressure boosting part.

3. The method for producing the foam-molded product according to claim 2 , wherein in the starvation zone, the diameter of the shaft of the plasticizing screw in the different part from the pressure boosting part is constant.

4. The method for producing the foam-molded product according to claim 2 , wherein the plasticizing cylinder further has a compression zone which is arranged on an upstream side of the starvation zone and in which the molten resin is compressed so as to increase pressure of the molten resin; and
a maximum value of the diameter of the shaft of the plasticizing screw in the pressure boosting part is smaller than that of the plasticizing screw in the compression zone.

5. The method for producing the foam-molded product according to claim 4 , wherein the plasticizing cylinder satisfies the following expression (1):
0.5DS 2 <DS 1 <0.95DS 2   (1)

in the expression (1),
DS 1 : the maximum value of the diameter of the shaft of the plasticizing screw in the pressure boosting part, and
DS 2 : the maximum value of the diameter of the shaft of the plasticizing screw in the compression zone.

6. The method for producing the foam-molded product according to claim 1 , wherein the plasticizing cylinder satisfies the following expression (2):
0.5DC≤L≤2DC  (2)

in the expression (2),
L: length of the pressure boosting part in an extending direction of the plasticizing screw, and
DC: inner diameter of the plasticizing cylinder.

7. The method for producing the foam-molded product according to claim 1 , wherein the producing apparatus further includes an introducing speed adjusting container connected to the introducing port of the plasticizing cylinder;
a maximum value of inner diameter of the introducing speed adjusting container is greater than inner diameter of the introducing port;
the method further comprises supplying the pressurized fluid having the fixed pressure into the introducing speed adjusting container; and
the pressurized fluid having the fixed pressure is introduced from the introducing speed adjusting container into the starvation zone.

8. The method for producing the foam-molded product according to claim 1 , wherein the fixed pressure is in a range of 1 MPa to 20 MPa.

9. The method for producing the foam-molded product according to claim 1 , wherein in a case of bringing the molten resin in the starved state into contact with the pressurized fluid having the fixed pressure in the starvation zone, pressure of the molten resin in the pressure boosting part is higher than the fixed pressure.

10. The method for producing the foam-molded product according to claim 9 , wherein an absolute value of difference between the pressure of the molten resin in the pressure boosting part and the fixed pressure is not more than 4 MPa.

11. The method for producing the foam-molded product according to claim 9 , wherein the fixed pressure is less than 6 MPa.

12. The method for producing the foam-molded product according to claim 1 , wherein in a case of bringing the molten resin in the starved state into contact with the pressurized fluid having the fixed pressure in the starvation zone, the starvation zone is maintained at the fixed pressure.

13. The method for producing the foam-molded product according to claim 12 , wherein the fixed pressure is not less than 6 MPa.

Assignees

• Maxell Ltd

Inventors

• Yusa Atsushi
• Yamamoto Satoshi
• Goto Hideto

Classifications

• B29B7/7414

  with rotatable stirrer, e.g. using an intermeshing rotor-stator system (B29B7/7423 takes precedence) · CPC title

• B29C45/62

  Barrels or cylinders · CPC title

• B29K2105/04

  cellular or porous · CPC title

• B29C44/00 Primary

  Shaping by internal pressure generated in the material, e.g. swelling or foaming {; Producing porous or cellular expanded plastics articles} · CPC title

• B29C48/285 Primary

  Feeding the extrusion material to the extruder · CPC title