{
  "patent_number": "US 3953566",
  "country": "US",
  "title": "Making Strong, Porous PTFE: The Gore-Tex Process",
  "original_title": "Process for producing porous products",
  "summary": "This patent describes a specific process for rapidly stretching a highly crystalline form of PTFE plastic to create a strong, porous material with a unique internal structure, forming the basis for products like Gore-Tex.",
  "what_it_does": "The patent describes a process (Claim 1) for making a porous product from a polymer of tetrafluoroethylene, also known as PTFE. First, a shaped article of \"highly crystalline poly(tetrafluoroethylene)\" is created using a \"paste-forming extrusion technique.\" After removing any lubricant, this unsintered article is stretched at a very fast rate, \"exceeding about 10% per second\" (Claim 1), while kept at a temperature between about 35°C and the material's crystalline melt point (Claim 1). This rapid stretching creates a material with a unique microstructure of \"nodes interconnected by fibrils,\" as mentioned in the abstract, resulting in high porosity (Claim 13, 40-97%) and strength. For example, a PTFE rod could be stretched rapidly to become a porous tube, which could then be used in a waterproof fabric.",
  "what_it_does_not_cover": [
    "Does not cover making porous PTFE by methods other than rapid stretching of a paste-extruded, highly crystalline PTFE article.",
    "Does not cover stretching PTFE at rates slower than about 10% per second (Claim 1).",
    "Does not cover stretching PTFE outside the temperature range of about 35°C and its crystalline melt point (Claim 1).",
    "Does not cover porous PTFE products made from materials that are not \"highly crystalline poly(tetrafluoroethylene)\" (Claim 1).",
    "Does not cover the final porous product itself, only the specific process of making it."
  ],
  "filed": "1973-07-03",
  "granted": "1976-04-27",
  "expires": "1993-07-03",
  "status": "expired",
  "holder": "WL Gore and Associates Inc",
  "holder_url": "https://patentbrief.org/company/wl-gore-and-associates-inc",
  "inventors": [
    {
      "name": "Robert W. Gore",
      "url": "https://patentbrief.org/inventor/robert-w-gore"
    }
  ],
  "times_cited": 1364,
  "tags": [
    "materials",
    "consumer_electronics",
    "automotive",
    "aerospace",
    "medical",
    "textiles",
    "industrial_manufacturing"
  ],
  "abstract": "This invention provides a tetrafluoroethylene polymer in a porous form which has an amorphous content exceeding about 5% and which has a micro-structure characterized by nodes interconnected by fibrils. The material has high porosity and high strength. It can be used to produce all kinds of shaped articles such as films, tubes, rods, and continuous filaments. Laminations can be employed and impregnation and bonding can readily be used to produce a large variety of articles. Compressed articles of very high strength can also be produced from these porous forms.",
  "url": "https://patentbrief.org/patent/us/3953566/gore-tex-expanded-ptfe",
  "markdown_url": "https://patentbrief.org/patent/us/3953566/gore-tex-expanded-ptfe/md",
  "google_patents_url": "https://patents.google.com/patent/US3953566",
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}