Method of manufacturing thermoplastic polyester resin foam by extrusion

• US 5,958,164 A
• Filed: 12/27/1995
• Issued: 09/28/1999
• Est. Priority Date: 12/27/1994
• Status: Expired due to Fees

• Current Assignee: Sekisui Kaseihin Kogyo Kabushiki Kaisha (Sekisui Kasei Co., Ltd.)
• Original Assignee: Sekisui Kaseihin Kogyo Kabushiki Kaisha (Sekisui Kasei Co., Ltd.)
• Inventors: Shindo, Masahiro, Hirai, Takaaki, Yoshioka, Kiyoshi, Tsubone, Masahiro, Tsujiwaki, Nobuyuki, Ishiwatari, Susumu
• Primary Examiner(s): CRISPINO, RICHARD D
• Application Number:
  US08/579,271
• Time in Patent Office: 1,371 Days
• Field of Search: 156/78, 156/94, 156/244.18, 156/244.19, 156/244.21, 156/244.24, 156/244.27, 156/245, 156/267, 156/307.1, 264/36, 264/45.9, 264/50, 264/51, 264/53, 264/54, 264/101, 264/102, 264/146, 264/151, 264/211.23, 264/211.24, 264/321, 264/565, 264/37.1
• US Class Current: 156/78
• CPC Class Codes: B29B 17/0026 by agglomeration or compacting
• CPC Class Codes: B29B 17/0042 for shaping parts, e.g. multilayered parts with at least one layer containing regenerated plastic
• CPC Class Codes: B29B 17/04 Disintegrating plastics, e.g. by millingB29B9/02, B29B11/02, B29B13/10, B29B17/02 take precedence
• CPC Class Codes: B29C 44/20 for articles of indefinite length
• CPC Class Codes: B29C 44/348 by regulating the temperature and/or the pressure, e.g. suppression of foaming until the pressure is rapidly decreased
• CPC Class Codes: B29C 44/507 extruding the compound through an annular die in general B29C48/03
• CPC Class Codes: B29C 48/04 Particle-shaped making granules B29B9/00
• CPC Class Codes: B29C 48/10 flexible, e.g. blown foils
• CPC Class Codes: B29C 48/29 in liquid form
• CPC Class Codes: B29C 48/297 at several locations, e.g. using several hoppers or using a separate additive feeding
• CPC Class Codes: B29C 48/37 Gear pumps
• CPC Class Codes: B29C 48/39 a first extruder feeding the melt into an intermediate location of a second extruder
• CPC Class Codes: B29C 48/40 using two or more parallel screws or at least two parallel non-intermeshing screws, e.g. twin screw extruders
• CPC Class Codes: B29C 48/76 Venting , drying means; Degassing means
• CPC Class Codes: B29K 2067/00 Use of polyesters or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2105/04 cellular or porous
• CPC Class Codes: B29K 2105/16 Fillers
• CPC Class Codes: B29K 2105/26 Scrap or recycled material
• CPC Class Codes: B29L 2031/7158 Bottles
• CPC Class Codes: C08J 2201/03 Extrusion of the foamable blend
• CPC Class Codes: C08J 2203/14 : Saturated hydrocarbons, e.g. butane; Unspecified hydrocarbons
• CPC Class Codes: C08J 2300/30 : Polymeric waste or recycled polymer
• CPC Class Codes: C08J 2367/02 : Polyesters derived from dicarboxylic acids and dihydroxy compounds; C08J2367/06 takes precedence
• CPC Class Codes: C08J 2467/02 : Polyesters derived from dicarboxylic acids and dihydroxy compounds C08J2467/06 takes precedence
• CPC Class Codes: C08J 9/0061 : characterized by the use of several polymeric components
• CPC Class Codes: C08J 9/141 : Hydrocarbons
• CPC Class Codes: Y02W 30/62 : Plastics recycling; Rubber recycling
• CPC Class Codes: Y10T 428/249953 : Composite having voids in a component [e.g., porous, cellular, etc.]
• CPC Class Codes: Y10T 428/31786 : Of polyester [e.g., alkyd, etc.]
• CPC Class Codes: Y10T 428/31794 : Of cross-linked polyester

Abstract

A thermoplastic polyester resin is fed into a twin extruder, wherein a resin is heated for melting, thereby removing moisture in the resin by evacuating and sucking from a vent port thereof, injecting a foaming agent into the resin to which is pushed out as a foaming sheet and, after that, forming the foaming sheet which is divided into a forming body and a trimming loss, whereby the trimming loss is crushed to obtain crushed materials which are provided so as to put the materials into the twin extruder as collection materials and recycle them.

Claims

1. A method for manufacturing thermoplastic polyester resin foam comprising:

a melting and kneading step for melting and kneading a composition comprising at least one moisture-containing thermoplastic polyester resin in a first stage comprising an extruder comprising at least one twin screw,

a moisture removing step for removing moisture in the molten resin by venting said molten resin under vacuum from said first stage,

a foaming agent infecting step for infecting a foaming agent into the dehumidified molten resin to modify the resin into a foaming molten resin in a second stage, and an extrusion foaming step for extruding and foaming the foaming molten resin into a low pressure region,

wherein the composition comprising the thermoplastic polyester resin further comprises a fluoroplastic.

2. A method for manufacturing thermoplastic polyester resin foam comprising:

a melting and kneading step for melting and kneading a composition comprising at least one moisture-containing thermoplastic polyester resin and a fluoroplastic,

a moisture removing step for removing moisture in the molten resin by venting said molten resin under vacuum,

a foaming agent injecting step for injecting a foaming agent into the dehumidified molten resin to modify the resin into a foaming molten resin, and

an extrusion foaming step for extruding and foaming the foaming molten resin into a low pressure region.

3. A method for manufacturing thermoplastic polyester resin foam as recited in claim 2, wherein the molten and kneaded thermoplastic polyester resin is crosslinked to increase the weight-average molecular weight of the thermoplastic polyester resin.

4. A method for manufacturing thermoplastic polyester resin foam as recited in claim 3, wherein the foaming molten resin is foamed more than three times, and the weight-average molecular weight of the foam is increased in the range of 80,000 to 250,000.

5. A method for manufacturing thermoplastic polyester resin foam as recited in claim 2, wherein the shape of the extruded foaming resin is in the form of a sheet, plate or board.

6. A method for manufacturing thermoplastic polyester resin foam as recited in claim 2, wherein the melting and kneading step and moisture removing step are carried out by a twin screw extruder, and the foaming agent injecting step and extrusion foaming step are carried out by a single screw extruder.

7. A method for manufacturing thermoplastic polyester resin foam as recited in claim 2, wherein the moisture removing step is performed by applying a pressure of 20 Torr or less.

8. A method for manufacturing thermoplastic polyester resin foam as recited in claim 2, wherein the thermoplastic polyester resin is either a fresh material or a recovered material.

9. A method for manufacturing thermoplastic polyester resin foam as recited in claim 8, wherein the recovered material is foamed or unfoamed ground material.

10. A method for manufacturing thermoplastic polyester resin foam as recited in claim 9, wherein the ground material is of a size passing through 15 mm diameter punch holes.

11. A method for manufacturing thermoplastic polyester resin foam as recited in claim 2, wherein the thermoplastic polyester resin is a mixture of fresh material and recovered material.

12. A method for manufacturing thermoplastic polyester resin foam as recited in claim 6, wherein at least part of said thermoplastic polyester resin comprises recovered material of foamed or unfoamed ground material.

13. A method for manufacturing thermoplastic polyester resin foam as recited in claim 2, wherein a crosslinking agent is added to the thermoplastic polyester resin before or during the melting and kneading step.

14. A method for manufacturing thermoplastic polyester resin foam as recited in claim 2, wherein said fluoroplastic is polytetrafluoroethylene resin.

15. A method for manufacturing thermoplastic polyester resin foam as recited in claim 2, further comprising:

a forming step for forming the foam extruded and foamed in the extrusion foaming step into a formed piece of a specific shape,

a cutting step for cutting off a trimming loss portion of said formed piece,

a grinding and recovering step for grinding the trimming loss portion and collecting as recovered material, and

a recovered material feedback step for feeding back the recovered material into the melting and kneading step.

16. A method for manufacturing thermoplastic polyester resin foam product, comprising:

a melting and kneading step for melting and kneading a composition comprising at least one moisture-containing thermoplastic polyester resin and a fluoroplastic,

a moisture removing step for removing moisture in the molten resin by venting said molten resin under vacuum,

a foaming agent infecting step for injecting a foaming agent into the dehumidified molten resin to modify the resin into a foaming molten resin,

an extrusion foaming step for extruding and foaming the foaming molten resin into a low pressure region to obtain a foam, and

a film laminating step for laminating the foam with a film.

17. A method for manufacturing thermoplastic polyester resin foam as recited in claim 16, wherein at least a portion of the thermoplastic polyester resin comprises recovered material, and said thermoplastic polyester resin is crosslinked in the melting and kneading step to increase the weight-average molecular weight of the thermoplastic polyester resin, and the foam extruded and foamed in the extrusion foaming step is laminated with a film of fresh material or a metal foil.

18. A method for manufacturing thermoplastic polyester resin foam as recited in claim 17, wherein the foam laminated with the film or metal foil is formed into a specific shape.