All posts in category Isocyanates and Prepolymers

Flexible Foams from Inverse NOP Prepolymers

Title: Polyurethane Foam

Number/Link:US2014329923

Applicant/Assignee: Green Urethanes

Publication date: 06-11-2014 (priority PCT)

“Gist”: Flexible polyurethane foams based on OH-ended natural-oil polyol prepolymers

Why it is interesting: Polyols based on natural oils (NOPs) such as rapeseed-, soy-, castor oil and the like are hydrophobic, have sterically hindered hydroxyl groups and are therefore not compatible with conventionally used polyols and isocyanates. The amount of natural oil-based polyols that can be used is therefore limited to less than about 30% for conventional flexible slabstock and even less (5-10%) for HR foams. According to the current invention, prepolymerizing the NOP with a multifunctional isocyanate to form an OH-ended (‘inverse’) prepolymer, improves compatibility and reactivity and even reduces or eliminates the typical smell associated with these compounds. In the examples about 10% of the OH groups of different types of NOPs are pre-reacted with polymeric MDI using a gelling catalyst. The prepolymers are then foamed using TDI, water and conventional polyols. Flexible foams are produced containing 50-75% NOP on the total amount of polyol used.

Typical castor oil component

Poly (Urethane-Urea) Elastomers from High 2,6-TDI

Title: Polyurethane Elastomers Based on TDI Prepolymers Enriched in the 2,6-TDI Isomer Cured with Trimethylene Glycol Di-(para Amino Benzoate)

Number/Link: US2014/0309397

Applicant/Assignee: Anderson Development

Publication date: 16-10-2014

“Gist”: Elastomers are prepared from TDI containing a high amount of the 2,6 isomer.

Why it is interesting: Commercially available toluene diisocyanate (TDI) usually comes in the 80/20 or the 65/35 2,4/2,6 isomer blend. It is known that higher 2,6 levels result in stiffer hardblocks and a different reaction profile because of the (initially) equal reactivity of the isocyanate groups. According to this invention elastomers prepared from TDI with a 2,6 content of (most preferred) at least 60% results in superior green strength and dimensional stability. High 2,6 TDI-PTMEG prepolymers cured with trimethylene glycol di(p-aminobenzoate) (TGDBA) should even have a superior tear strength and upper hardness limit compared to MDI based elastomers.

TGDBA

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 Isocyanates and Prepolymers

Flexible Foams from Inverse NOP Prepolymers

Poly (Urethane-Urea) Elastomers from High 2,6-TDI

Isocyanate-Free Polyurethanes Using Azide-Alkyne Click Chemistry

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