All posts tagged thiols

Polythiourethanes for 3D Printing

Patent Title: THIOURETHANE POLYMERS, METHOD OF SYNTHESIS THEREOF AND USE IN ADDITIVE MANUFACTURING TECHNOLOGIES

Number/Link: WO2017/160810

Applicant/Assignee: Univ. Texas

Publication date: 21-September-2017

“Gist”: Photolatent bases are used to catalyse the polythiol-polyisocyanate reaction

Why it is interesting: According to this invention reactive systems useful for additive manufacturing processes can be prepared from polythiols, diisocyanates and a photolatent base. When irradiated the photolatent base will split off a non-nucleophilic base which will catalyse the thiol-isocyanate reaction. The systems can be prepared such that the resulting materials show improved mechanical properties over current 3D printed materials. In an example 2,2′-(ethylenedioxy)diethanethiol and pentaerithritol tetrakis(3-mercaptopropionate) are reacted with HDI using 1,1-dimethyl-1-(2-hydroxypropyl)amine-p-nitrobenzimide (DANBA) as a photolatent base.

Example of pholatent base (DANBA)

Hybrid Hotmelt Adhesive with Low Free Isocyanate

Title: POLYURETHANE HOT-MELT ADHESIVE HAVING A LOW CONTENT OF DIISOCYANATE MONOMERS AND GOOD CROSS-LINKING SPEED

Number/Link: WO2015/135833 (German)

Applicant/Assignee: Sika

Publication date: 17-09-2015

“Gist”: Use of mercaptosilane to reduce free monomeric diisocyanate

Why it is interesting: Reduction of the amount of free monomeric diisocyanate in adhesives, coatings, OCF systems etc. remains a hot topic in industrial polyurethane research, mostly because of changing legislation. For example, in the EU the amount of free MDI needs to be below 1% in order to avoid “R-40” (suspect carcinogen) labeling. A number of strategies to reduce free isocyanate have been tried in the past (and mentioned in this blog). Examples are distillation, the use of asymmetric diisocyanates and the use of monols. According to this invention the amount of free monomeric isocyanate in a hotmelt formulation can be reduced by adding a mercaptosilane like e.g. mercaptopropyltrimethoxysilane. The mercaptosilane is said to react preferentially with the monomeric isocyanate. Only a relatively small amount of mercaptosilane is used such that the main curing mechanism is still the isocyanate-water reaction.

Mercaptopropyltrimethoxysilane

PU Sealants using Michael Addition Chemistry

Title: MICHAEL ACCEPTOR-TERMINATED URETHANE-CONTAINING FUEL RESISTANT PREPOLYMERS AND COMPOSITIONS THEREOF

Number/Link: US2015/0252232

Applicant/Assignee: PRC-DeSoto

Publication date: 10-09-2015

“Gist”: A PU prepolymer is capped with Michael accepting groups and then cured with a dithiol

Why it is interesting: This invention is about sulphur containing PU sealants with properties acceptable for the aerospace industry. A bis(vinylsulfonyl)- terminated urethane-polythioether prepolymer is prepared according to the scheme below. The prepolymer can then be cured with a dithiol-ended polyether, catalysed by a tertiary amine. The compositions have an extended pot life and the curing rate can be controlled by using an encapsulated tert-amine as a controlled-release catalyst.

Michael acceptor-terminated prepolymer preparation according to the invention

Innovation in Polyurethanes

All posts tagged thiols

Polythiourethanes for 3D Printing

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Hybrid Hotmelt Adhesive with Low Free Isocyanate

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PU Sealants using Michael Addition Chemistry

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