Polythiourethanes for 3D Printing

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

 Number/Link: WO2017/0267804

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)

Moisture Scavenger for Polyurethane Coatings

Title: PROCESSES FOR MOISTURE SCAVENGING IN PREPARING POLYURETHANE COATINGS AND COMPOSITIONS THEREFOR

Number/Link: US2017/0114247

Applicant/Assignee: Achiewell

Publication Date: 27-april-2017

“Gist”: Methoxysilicon compound with e-withdrawing group together with hydrophobic t-amine catalyst acts as moisture scavenger

Why it is interesting:  Moisture in PU coating compositions can be a problem because it negatively affects both the properties of the composition (pot life and viscosity..) and of the final coating. Moisture scavengers like molecular sieves are well known but often have a negative impact as well. According to this invention, methoxyorganosilicon compounds with at least one electron withdrawing group attached to the silicon atom act as efficient moisture scavengers when used in combination with a hydrophobic tert-methylamine catalyst. Preferred organosilicon compounds have 3 methoxy substituents and one hydrocarbon-based e-withdrawing group, like e.g. fluoroethyltrimethoxysilane. A preferred catalyst is 1,3-bis[3-dimethylaminopropyl]urea (claimed).  No examples are given.

1,3-bis[3-dimethylaminopropyl]urea

Infrared Curable 2K PU Adhesives

Patent Title: LATENT TWO-PART POLYURETHANE ADHESIVES CURABLE WITH INFRARED RADIATION

 Number/Link: WO2016/205251 and related cases: WO..5252, WO…5254 and WO..5255

Applicant/Assignee: Dow

Publication date: all published on 22 dec 2016

Gist”: Two-component PU adhesive using 3 different delayed-action catalysts

Why it is interesting: Two component adhesive systems need a sufficiently long ‘open time’ preferably combined with a fast cure once activated, e.g. by heat. Heat curing using infrared radiation allows for ‘spot curing’ , i.e. curing only predetermined parts of the adhesive such that the assembly can be handled and can be cured completely in a subsequent step.  This process is fast and saves energy.  The current invention is about IR curable adhesives containing 3 different types of latent catalysts: a latent room temperature organometallic catalyst based on Sn, Zn or Bi added to the polyol component, a phenol-blocked cyclic amidine and a carboxylic acid blocked cyclic amidine.  The two latter catalysts can either be included in the polyol or in the isocyanate component. The catalysts used in the examples are dioctyltinthioglycolate, phenol blocked 1,8-diazabicycloundec-7-ene and a carboxilic acid blocked 1,8-diazabicycloundec-7-ene.

1,8-diazabicycloundec-7-ene

1,8-diazabicycloundec-7-ene

Reactive Polyurethane Plasticizer

Patent Title: REACTIVE POLYURETHANE PLASTICIZERS AND ADHESIVES MADE THEREFROM

 Number/Link: W02016179131

Applicant/Assignee: Dow

Publication date: 10-11-2016

Gist”: An EO/PO monol is reacted with an excess of 4,4′-MDI

Why it is interesting: The invention is about reactive PU plasticizers which are said to be especially useful for polyurethane moisture curing adhesives used in automotive glass bonding. As opposed to conventional plasticizers they will supposedly not migrate and therefore not degrade adhesive properties over time or cause window fogging. The reactive plasticizers are prepared by reacting a slight excess of 4,4′-MDI with and EO/PO monol of MW between 500 and 2000 Da and an EO:PO ratio of about 1:1, such that the resulting in NCO content is between 0.1 and 1%.  Obviously at such low NCO values most of the MDI will have reacted twice with monol, and the resulting non-reactive plasticizer may (in my opinion) well migrate depending on the composition of both monol and adhesive.

4,4'-MDI

4,4′-MDI

 

Classic PU Patent of the Month: Microencapsulation (1963)

Patent Title: ENCAPSULATION BY INTERFACIAL POLYCONDENSATION

 Number/Link:  US3577515

Applicant/Assignee: Pennwalt Corp.

Publication date: 4-05-1971

Gist”: Interfacial polycondensation on the surface of emulsified droplets.

Why it is interesting: Micro-sized droplets are encapsulated with a polymeric film or ‘skin’ formed by an interfacial polycondensation reaction. The idea is both very clever and simple: one reaction component is dissolved in a liquid which is then dispersed in another -immiscible- liquid. The second reaction component is then added to the continuous phase resulting in a polycondensation reaction at the surface of the droplets, encapsulating these with a polymeric film. For example a solution of a polyisocyanates in an organic solvent can be dispersed in water (to a desired droplet size) after which a water soluble diol or diamine is added resulting in a polyurethane or polyurea film encapsulating the solvent droplets. Microcapsules are now common and used in may applications like cosmetics, phase change materials, e-paper, self-healing coatings etc.

Figure 1 illustrating the process

Figure illustrating the process