{
  "patent_number": "US 3691140",
  "country": "US",
  "title": "Sticky, Tiny Plastic Balls Made from Acrylates",
  "original_title": "Acrylate copolymer microspheres",
  "summary": "This 1972 patent describes how to make tiny, sticky, and durable plastic balls (microspheres) using a specific mix of acrylate chemicals and a special water-based process.",
  "what_it_does": "This patent details the creation of microscopic, solid balls, called microspheres, that are inherently sticky and can be dispersed in solvents but don't dissolve in them. They are made from a blend of acrylate esters (like iso-octyl acrylate) and a small amount of another chemical, either an ionic monomer or maleic anhydride. The process involves suspending these ingredients in water and using a specific amount of emulsifier, a substance that helps mix oil and water, to create the microspheres. The resulting tiny balls are described as infusible, meaning they can't be melted down, and elastomeric, meaning they can stretch and return to their original shape.",
  "what_it_does_not_cover": [
    "Microspheres made from monomers other than alkyl acrylates and specific ionic monomers or maleic anhydride.",
    "Microspheres that are soluble in organic solvents.",
    "Microspheres created using polymerization processes that don't involve an aqueous suspension.",
    "Microspheres made with emulsifier amounts below the critical micelle concentration.",
    "Microspheres that are not inherently tacky or elastomeric."
  ],
  "filed": "1970-03-09",
  "granted": "1972-09-12",
  "expires": "1990-03-09",
  "status": "expired",
  "holder": "Individual",
  "holder_url": "https://patentbrief.org/company/individual",
  "inventors": [
    {
      "name": "Spencer Ferguson Silver",
      "url": "https://patentbrief.org/inventor/spencer-ferguson-silver"
    }
  ],
  "times_cited": 382,
  "tags": [
    "materials",
    "consumer_electronics",
    "chemicals",
    "adhesives"
  ],
  "abstract": "Infusible, solvent-dispersible, solvent-insoluble, inherently tacky, elastomeric copolymer microspheres consist essentially of about 90 percent to about 99.5 percent by weight of at least one alkyl acrylate ester and about 10 to about 0.5 percent by weight of at least one monomer selected from the group consisting of substantially oil-insoluble, water-soluble, ionic monomers and maleic anhydride. The microspheres are prepared by aqueous suspension polymerization utilizing emulsifier in an amount greater than the critical micelle concentration in the absence of externally added protective colloids or the like.",
  "url": "https://patentbrief.org/patent/us/3691140/post-it-repositionable-adhesive",
  "markdown_url": "https://patentbrief.org/patent/us/3691140/post-it-repositionable-adhesive/md",
  "google_patents_url": "https://patents.google.com/patent/US3691140",
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}