{
  "patent_number": "US 4166152",
  "country": "US",
  "title": "The Sticky Microscopic Beads Behind Post-it Notes",
  "original_title": "Tacky polymeric microspheres",
  "summary": "3M's 1977 patent on tiny, naturally sticky plastic beads that can stick to a surface, peel off easily without leaving residue, and be reused over and over again.",
  "what_it_does": "This patent describes microscopic, rubbery polymer spheres (microspheres) made from acrylate or methacrylate chemicals. These spheres are designed to be 'infusible' (they won't melt) and 'solvent-insoluble' (they won't dissolve), but they can be suspended in a liquid to be coated onto paper. Because they have a glass transition temperature below -20 degrees Celsius, they remain soft and sticky at room temperature. When coated onto a substrate like paper, these tiny spheres act as pressure-sensitive adhesive dots. Because they are spheres, they only touch a wall or desk at tiny contact points, creating a light bond that can be easily peeled off and restuck without leaving sticky residue behind.",
  "what_it_does_not_cover": [
    "Does not cover adhesives made of continuous, flat polymer films instead of discrete microspheres.",
    "Does not cover microspheres made using non-ionic emulsifiers or ionic emulsifiers below their critical micelle concentration.",
    "Does not cover microspheres with a glass transition temperature above -20 degrees Celsius, which would be rigid and non-tacky at room temperature.",
    "Does not cover microspheres that dissolve completely in organic solvents."
  ],
  "filed": "1977-08-17",
  "granted": "1979-08-28",
  "expires": "1997-08-17",
  "status": "expired",
  "holder": "Minnesota Mining and Manufacturing Co",
  "holder_url": "https://patentbrief.org/company/minnesota-mining-and-manufacturing-co",
  "inventors": [
    {
      "name": "William A. Baker",
      "url": "https://patentbrief.org/inventor/william-a-baker"
    },
    {
      "name": "Warren D. Ketola",
      "url": "https://patentbrief.org/inventor/warren-d-ketola"
    }
  ],
  "times_cited": 278,
  "tags": [
    "materials"
  ],
  "abstract": "Infusible, solvent-insoluble, solvent-dispersible, inherently tacky, elastomeric polymeric microspheres which are formed from non-ionic monomers and comprise at least one oleophilic water-emulsifiable alkyl acrylate or methacrylate ester, and a suspension polymerization technique for producing the microspheres, which includes the use of an ionic suspension stabilizer.",
  "url": "https://patentbrief.org/patent/us/4166152/post-it-note-adhesive",
  "markdown_url": "https://patentbrief.org/patent/us/4166152/post-it-note-adhesive/md",
  "google_patents_url": "https://patents.google.com/patent/US4166152",
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}