Search

CN-121986019-A - Thermoplastic polymer foam and method for producing same

CN121986019ACN 121986019 ACN121986019 ACN 121986019ACN-121986019-A

Abstract

A thermoplastic foam article comprising a thermoplastic polyurethane composition. The thermoplastic polyurethane composition comprises a blowing agent and a nucleating agent. The average density reduction amplitude or porosity of the thermoplastic polyurethane foam article is greater than 10%.

Inventors

  • Abogaz Mohebi
  • O. K. Durbin
  • Little Christopher David Tatters
  • Andrew Temparsky
  • N. Albanese

Assignees

  • 莫西埃特有限责任公司

Dates

Publication Date
20260505
Application Date
20240620
Priority Date
20230620

Claims (20)

  1. 1. A method of forming a foamed article, the method comprising: providing a thermoplastic polymer; adding a thermoplastic polymer, a blowing agent in an amount of from 0.01wt.% to about 5wt.%, and a nucleating agent in an amount of from about 0.01wt.% to about 4.0wt.% to a melt zone of an injection molding machine to form a mixture; melting the mixture in a melt zone of an injection molding machine; Injecting the mixture into a mold cavity; Cooling the mold cavity, and The article is removed from the mold cavity and, Wherein the cell structure of the foamed article has structural uniformity in cell size and cell density throughout the article.
  2. 2. The method of claim 1, wherein the thermoplastic polymer is selected from thermoplastic polyurethane, thermoplastic elastomer, thermoplastic vulcanizate, or mixtures thereof.
  3. 3. The method of claim 1, wherein the injection molding machine further comprises at least one hopper for storing the thermoplastic polymer, the foaming agent, and/or the nucleating agent and configured to selectively deliver the thermoplastic polymer, the foaming agent, and/or the nucleating agent to a melt zone of the injection molding machine.
  4. 4. The method of claim 1, wherein the thermoplastic polymer, the blowing agent, and/or the nucleating agent are simultaneously delivered to a melt zone of the injection molding machine, and the thermoplastic polymer, the blowing agent, and/or the nucleating agent are mixed in the melt zone until the mixture reaches a homogeneous state.
  5. 5. The method of claim 1, wherein the mixture is heated to a temperature of about 190 ℃ to 245 ℃ within an injection molding machine.
  6. 6. The method of claim 1, wherein the mixture further comprises an additive.
  7. 7. The method of claim 1, wherein the cell structure of the formed article has structural uniformity from one outer surface to another.
  8. 8. The method of claim 1, wherein the cell structure of the formed article has structural uniformity in cell wall thickness.
  9. 9. The method of claim 1, wherein the foamed article has a cell size of less than 900 μιη.
  10. 10. The method of claim 6, wherein the foamed article has a cell size of 200 μιη to 600 μιη.
  11. 11. The method of claim 1, wherein the foamed article has a cell density greater than 1000 cells/cm 3 .
  12. 12. The method of claim 8, wherein the foamed article has a cell density of 1000 cells/cm 3 to 60000 cells/cm 3 .
  13. 13. The method of claim 1, wherein the article is characterized as having uniform reactivity over a plurality of compression stress cycles.
  14. 14. A thermoplastic polymer foamed article comprising a mixture of: a thermoplastic polymer; A blowing agent in an amount of from 0.01wt.% to about 2.5wt.%, and A nucleating agent in an amount of about 0.01wt.% to about 2.0 wt.%; Wherein the molding conditions of the thermoplastic foamed article include an injection temperature of 190 ℃ to 245 ℃, and The thermoplastic foamed articles formed by this process are characterized by a structural uniformity of cell size and cell density throughout the article.
  15. 15. The article of claim 14, wherein the foamed article has a cell size of 200 μιη to 600 μιη.
  16. 16. The article of claim 14, wherein the foamed article has a cell density of 1000 cells/cm 3 to 60000 cells/cm 3 .
  17. 17. The article of claim 14, wherein 75% of the cells have a roundness of 0.900 to 1.00.
  18. 18. The article of claim 14, wherein the article is characterized by a compressive stress of less than 1.5 megapascals.
  19. 19. The article of claim 4, wherein the article is characterized by a uniform reactivity over a plurality of compression stress cycles.
  20. 20. The article of claim 14, wherein the mixture further comprises an additive.

Description

Thermoplastic polymer foam and method for producing same Cross Reference to Related Applications The present application claims priority from U.S. provisional patent application No. 63/509,143 filed on 6/20 of 2024, the entire contents of which are incorporated herein by reference. Technical Field The present disclosure relates generally to thermoplastic foams. More specifically, the present disclosure relates to injection molding processes and formulations for forming thermoplastic foams having particularly preferred cell structures, physical properties, and mechanical properties. Background Some thermoplastic polymers, such as Thermoplastic Polyurethane (TPU), thermoplastic elastomer (TPE) and thermoplastic vulcanizate (TPV), while exhibiting the mechanical properties of rubber, such materials can be processed through injection molding processes like typical plastic materials. For example, TPU is a random block copolymer comprising hard and soft segments, forming a two-phase microstructure that behaves as a "spring and damper" mechanism that results in unique viscoelastic behavior. The hard segments act as physical crosslinks, which contain a large number of chain entanglements and exhibit a chemical crosslinking like in rubber, resulting in elastic behavior, while the soft segments have a temperature above their glass transition temperature at room temperature, resulting in rubber-like behavior. The temperature of the hard phase at room temperature below its glass transition temperature plays a major role in determining set, hysteresis and high modulus. Thus, TPU exhibits a combination of high elasticity and high abrasion resistance, making it widely used in industries such as aerospace, furniture, and footwear. The thermoplastic may be "foamed" by introducing a foaming agent while melting the polymer matrix in the injection molding machine. Foamed thermoplastics generally comprise an internal cell structure. A number of parameters, including process settings and formulations, control this cell structure and the final mechanical and physical properties of the articles formed from the foamed thermoplastic. It is difficult to select the formulation and corresponding process parameters to form a thermoplastic foam having predictable and desired properties. In general, articles made from foamed thermoplastics have a uniform cell structure, as well as non-uniform and undesirable mechanical and physical properties. For example, prior art foamed thermoplastic articles may contain large internal cavities, resulting in failure of the article under load. The structure of prior art thermoplastic foam articles typically comprises two phases, the first phase comprising an internal cell structure, while the thick solid (solid) "skin" layer on the outer surface of the article does not contain any cell structure. The methods, systems, and articles disclosed herein describe and illustrate the formulation and process of thermoplastic foams to produce articles having desirable physical and mechanical properties controlled by a uniform cell structure throughout the article. Disclosure of Invention Disclosed herein are thermoplastic foam articles and methods of making the same. In one example, a thermoplastic polyurethane foam article comprises a thermoplastic polyurethane composition. The thermoplastic polyurethane composition comprises a blowing agent and a nucleating agent. The average density of the thermoplastic polyurethane foam article is reduced by more than 10%. The thermoplastic polyurethane article has a uniform cell structure throughout the article, including from one surface of the article to all other surfaces of the article. In another example, a method of forming a thermoplastic polyurethane foam article includes adding a blowing agent and a nucleating agent to a thermoplastic polyurethane composition. The method includes melting a thermoplastic polyurethane composition and forming it into an article having a uniform cell structure. Drawings Structures are shown in the drawings, which together with the detailed description provided below, describe exemplary embodiments of the disclosed systems, methods and devices. Where appropriate, like elements are identified with the same or similar reference numerals. Elements shown as a single component may be replaced by multiple components. Elements shown as multiple components may be replaced by a single component. The figures may not be drawn to scale. The proportions of some of the elements may be exaggerated for convenience of illustration. Fig. 1 schematically shows the structure of a thermoplastic foam article. Fig. 2 schematically shows the structure of a thermoplastic foam article having ellipsoidal cells. Fig. 3 is an image depicting a cross-section of a thermoplastic foam article formed from a formulation having a GPPS and HIPS mixture as the matrix resin. Fig. 3A is an enhanced image depicting a cross-section of the article shown in fig. 3. Fig. 4 is an ima