• and alkyl ketene dimer and alkenyl succinic anhydride used for sizing. (gdchemical.com)
  • Alkyl ketene dimers (AKDs) are a family of organic compounds based on the 4-membered ring system of oxetan-2-one, which is also the central structural element of propiolactone and diketene. (wikipedia.org)
  • Attached to the oxetane ring of technically relevant alkyl ketene dimers there is a C12 - C16 alkyl group in the 3-position and a C13 - C17 alkylidene group in the 4-position. (wikipedia.org)
  • As early as 1901, Edgar Wedekind published the synthesis of alkyl ketene dimers by the reaction of carboxylic acid chlorides with tertiary amines, the reaction products for polymers. (wikipedia.org)
  • Alkyl ketene dimers (AKD) are effective and highly hydrophobic sizing agents for the internal sizing of alkaline papers, but in some cases they may form deposits on paper machines and copiers. (lut.fi)
  • The primary reaction products of carboxylic acid chlorides with hydrogen atoms in α-position and tertiary amines were identified by Hermann Staudinger and Norman Thomas Mortimer Wilsmore as highly reactive ketenes (ethenones) which form 2-oxetanones with an alkylidene group when dimerizing in a [2+2] photocycloadditions. (wikipedia.org)
  • The industrial synthesis of alkylated ketenedimers (at that time still called ketoethenones) was patented in 1945 from long-chain carboxylic acid chlorides in inert solvents (such as diethyl ether or benzene) with triethylamine as tertiary amine under anhydrous conditions. (wikipedia.org)
  • The synthesis and characterization of hexadecyl ketene dimer, a key substance for alkylated ketene dimers used in the paper industry, was first described in a patent in 1945 and in a publication in 1947. (wikipedia.org)
  • In addition to the significantly more reactive alkenylsuccinic anhydrides (which do also hydrolyze rapidly in the presence of water) alkylated ketene dimers have begun to be preferred surface and mass sizes in the paper industry from the 1960s onwards, beginning in the 1950s. (wikipedia.org)
  • There has been some concern that lime sludge may interfere with the development of paper's hydrophobicity in comparison with commercial PCC and ground calcium carbonate (GCC) due to the presence of impurities when alkyl ketene dimer (AKD) is used as the sizing additive. (ncsu.edu)
  • For example, the simple ketene (H2C=C=O) dimerizes to diketene (4-methylen-oxetan-2-one), while substituted ketenes, such as dimethyl ketene (Me2C=C=O, formed from isobutyryl chloride with triethylamine) dimerize in a head-to-tail addition to 2,2,4,4-tetramethylcyclobutanedione. (wikipedia.org)
  • Alkyl ketene dimers (AKDs) are a family of organic compounds based on the 4-membered ring system of oxetan-2-one, which is also the central structural element of propiolactone and diketene. (wikipedia.org)
  • Attached to the oxetane ring of technically relevant alkyl ketene dimers there is a C12 - C16 alkyl group in the 3-position and a C13 - C17 alkylidene group in the 4-position. (wikipedia.org)
  • As early as 1901, Edgar Wedekind published the synthesis of alkyl ketene dimers by the reaction of carboxylic acid chlorides with tertiary amines, the reaction products for polymers. (wikipedia.org)
  • There has been some concern that lime sludge may interfere with the development of paper's hydrophobicity in comparison with commercial PCC and ground calcium carbonate (GCC) due to the presence of impurities when alkyl ketene dimer (AKD) is used as the sizing additive. (ncsu.edu)
  • 9.5), hydrolyzed Alkenyl Succinic Anhydride (ASA) or Alkyl ketene dimer (AKD) form covalent bond with the hydroxyl groups of cellulose and form an ester bond (b-keto esters). (paperonweb.com)
  • The primary reaction products of carboxylic acid chlorides with hydrogen atoms in α-position and tertiary amines were identified by Hermann Staudinger and Norman Thomas Mortimer Wilsmore as highly reactive ketenes (ethenones) which form 2-oxetanones with an alkylidene group when dimerizing in a [2+2] photocycloadditions. (wikipedia.org)