Ethyl Corporation

J Kenneth Presswood

Christopher J Nalepa

Gordon G Knapp

Alethea H O'Quinn

James H Simon

Aromatic diamines having one or two benzene rings, two ar-N-methylamino substituents, and ar-alkyl substituents in all positions ortho to the amino substituents are novel compounds which can be used in the preparation of polyurethanes, polyureas, polyurethane-urea polymers, and epoxy resins.

Secondary diamines

Aromatic diimines having one or two benzene rings, two ar-imino substituents corresponding to the formula --N.dbd.CH.sub.2, and ar-alkyl substituents in all positions ortho to the imino substituents are novel compounds which can be used in the preparation of polyurethanes, polyureas, polyurethane-urea polymers, and epoxy resins.

Aromatic diimines

A method of treating the surface of a mold to improve its release characteristics is disclosed. A coating of a polyamic acid solution comprising the reaction product of 2,2-bis[4-(aminophenoxy)phenyl]hexafluoropropane and an aromatic tetracarboxylic acid or dianhydride or ester derivative thereof is applied to the mold surface. The coating is cured at elevated temperatures to remove the solvent and form the corresponding polyimide.

Polyimides for mold release

Described is a way of sealing a carbon body such as monolithic graphite tooling so that it retains its vacuum integrity through numerous thermal cycles typical of thermoplastic processing. This is accomplished by (a) applying to the body surface a coating formulation composed of a carbon-filled solution of a polyamic acid formed by reaction between pyromellitic acid dianhydride and 2,2-bis[4-(aminophenoxy)phenyl]hexafluoropropane, and (b) heat curing the coated body to cause the polyamic acid to imidize into a thermally cured polyimide.

Method of coating carbon bodies

Reciprocating engine parts which involve substantially continuous frictional contact are coated with a solid film lubricant having excellent wear characteristics and adhesion. The parts in question are pistons, and the area to which the wear resistant solid lubricant film is bonded is the piston skirt--i.e., all or a portion of the area below the piston rings. The lubricant film is composed of a polyimide of 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoropropane ('4-BDAF') and an aromatic tetracarboxylic acid (or dianhydride or ester thereof) containing from 25 to 125 parts by weight of fluorinated carbon per 100 parts by weight of the polyimide resin ('phr'), and preferably about 30 to about 100 phr of the fluorinated carbon.

Pistons with wear resistant solid film lubricant coatings

Blends of 90-99 mol % of a polyhydroxyalkane containing 2-6 carbons and 2-3 hydroxyl groups and 1-10 mol % of an aromatic diamine having a pKb value greater than 11.3 are useful as chain extenders for polyurethanes derived from diphenylmethanediisocyanate (MDI) prepolymers. Their use overcomes the sensitivity to stoichiometry common to MDI prepolymer/polyhydroxyalkane systems and leads to the formation of cast elastomers having better green strength and a shorter demold time. The preferred blends are blends of 1,4-butanediol and di(alkylthio)toluenediamines.

Polyhydroxyalkane/aromatic diamine chain extenders

Mixtures of aromatic diamines, polyurethanes made therefrom, and processes for the preparation of the polyurethanes. The mixtures of aromatic diamines of the invention comprise a first aromatic diamine having a machine gel time of about 1 to 4 seconds in a 50,000 psi modulus RIM formulation reaction and the second aromatic diamine having a slower machine gel time of about 1.5 to 15 times that of the first aromatic diamine. The mixtures provide gel times of about 2.5 to 10 seconds, suitable for filling large molds such as automotive body panels. The novel aromatic diamine mixtures allow use of larger proportions of diamine to provide polyurethanes which are rigid but not brittle at demold and have unexpectedly superior flexural modulus properties. The polyurethanes formed with the chain extender mixtures of the invention have flexural modulus superior to polyurethanes formed from either of the diamines individually.

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Baton Rouge, LA, United States of America

J Kenneth Presswood