All posts in category Adhesives-Coatings

Hydrophobic Coatings from BO Polyols

Title: POLYURETHANE ENCAPSULATE

Number/Link: WO2014/176390

Applicant/Assignee: Dow

Publication date: 30-10-2014

“Gist”: Use of polybutyleneoxide polyols for hydrophobic encapsulants.

Why it is interesting: The encapsulation of water soluble compounds for controlled release, like e.g. plant nutrients and fertilizers, requires a relatively hydrophobic coating. Often this is accomplished with polyurethane coatings to which hydrophic compounds are added such as castor oil derivatives. These additives can however have a deleterious effect on other coating properties. According to this invention encapsulation coatings with good mechanical properties and improved water absorption and water vapour transmission properties can be prepared from polybutyleneoxide triols and polymeric MDI without the need for other additives.

Butylene oxide

Steam-Treated Polyisocyanurate

Title: PROCESS FOR MAKING URETHANE-ISOCYANURATES

Number/Link: WO2014/160616

Applicant/Assignee: Dow

Publication date: 2-10-2014

“Gist”: Treating PUR-PIR with hot water at superatmospheric pressure results in a Tg increase.

Why it is interesting: Fiber-reinforced phenol-formaldehyde composites are used to make pipes among other things. They are however not completely stable in hot humid conditions so that they are less well suited for off-shore piping systems for example. According to this patent application, polyisocyanurate (PIR) or polyurethane-polyisocyanurate (PUR-PIR) systems are more suitable materials for such applications because properties of these materials remain stable and -surprisingly- glass transition temperature increases when subjected to high pressure water or steam. In the examples PUR-PIR systems based on polymeric MDI submerged in water at 120°C and 3500 kPa for 7 days show indeed an increase in Tg. In my opinion it would be interesting to repeat the experiment with 4,4′-MDI based PUR/PIR. Because 4,4′ MDI will show a higher conversion rate to PIR the ‘steam effect’ may well dissapear.

Isocyanurate group

Isocyanate-Free Polyurethanes Using Azide-Alkyne Click Chemistry

Title: SYNTHESIS OF POLYURETHANE POLYMERS VIA COPPER AZIDE-ALKYNE CLICK CHEMISTRY FOR COATINGS, ADHESIVES, SEALANTS AND ELASTOMER APPLICATIONS

Number/Link: WO2014/122153

Applicant/Assignee: Sika

Publication date: 14-08-2014

“Gist”: Polyurethane prepolymers capped with azides and alkynes are reacted using copper catalysis.

Why it is interesting: Because of safety, health and envriromental issues, isocyanate-free systems have clearly been gaining in importance the last few years. Especially for coatings, adhesives and OCF applications, alternative curings systems are being developed. In the current invention an isocyanate-free system is based on the reaction between a prepolymer having at least two azide groups and a prepolymer having at least two alkyne groups. The reaction is copper catalyzed such that it can be performed at ambient temperature. The first prepolymer is (pref.) prepared by reacting an isocyanate ended prepolymer with glycidol (2,3-epoxy-1-propanol) and subsequently with sodium azide. The second prepolymer is similarly prepared by reacting an isocyanate ended prepolymer with propargyl alcohol (2-propyn-1-ol). The systems are said to be especially useful for roof coatings.

Example of an azide-alkyne reaction resulting in 1,4-disubstituded triazoles.

Innovation in Polyurethanes

All posts in category Adhesives-Coatings

Hydrophobic Coatings from BO Polyols

Steam-Treated Polyisocyanurate

Isocyanate-Free Polyurethanes Using Azide-Alkyne Click Chemistry

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