All posts in category composites

Hybrid Polyurethane-Epoxy Pultrusion System

Title: REINFORCED PULTRUDED POLYURETHANE AND PRODUCTION THEREOF

Number/Link: US2013/0309924

Applicant/Assignee: Bayer

Publication date: 21-11-2013 (priority PCT/DE)

“Gist”: A pultrusion matrix material is formulated from of an immiscible polyol blend together with one or more epoxides and MDI

Why it is interesting: Pultrusion matrix systems need a decent pot-life and, after curing, a high glass transition temperature and modulus. According to the invention this can be achieved by using an immiscible polyol mixture prepared from a) a relatively high MW PO polyol (e.g. PPG4000) and b) a blend of low MW polyols and chain extenders/crosslinkers, where the amount of a) is about 10-30% on the total polyol. This polyol system together with an epoxide (e.g. bisphenol A or the triglycidylether of trimethylolpropane) an isocyanate (e.g polymeric MDI) and optional additives results in a system useful for a pultrusion process. The examples show a pot-life of about 30 minutes and a Tg of about 150°C. The immiscible high MW PO polyol probably forms a seperate phase, thus increasing the Tg of the hard phase.

Diagram of the Putrusion Process (Wikipedia)

Polyurethane Prepregs prepared with Isosorbide

Title: STORAGE-STABLE POLYURETHANE-PREPREGS AND FIBRE COMPOSITE COMPONENTS PRODUCED THEREFROM

Number/Link: WO2013/139704

Applicant/Assignee: Bayer

Publication date: 26-09-2013

“Gist”: Polyurethane matrix materials for prepregs with very good storage stability are prepared from an NCO prepolymer together with isosorbide and delayed action catalysts.

Why it is interesting: Resins for “prepregs” (pre-impregnated fibre composites) need to have a low viscosity upon impregnation, a good storage stability and a fast ‘curing’ reaction preferably at a relatively low temperature. According to this invention all these properties can be met by using a 8-16% NCO prepolymer made from a polyester polyol and MDI, together with a dianhydrohexitol (preferably isosorbide) as chain extender and a delayed action catalyst (e.g. a blocked amine) which is activated between 50 and 100°C. The resulting prepregs have a storage stability at room temperature of several weeks. Final Tg is said to be 130°C, which is not very high but should suffice for many applications.

Isosorbide

Low Viscosity Systems for Fibre-Reinforced PU Composites

Title: 2K POLYURETHANE SYSTEMS WITH PHASE SEPARATION – AND- 2K POLYURETHANE SYSTEMS WITH A HIGH GLASS-TRANSITION TEMPERATURE

Number/Link: WO2013/127732 and WO2013/127734

Applicant/Assignee: Henkel

Publication date: 6-09-2013

“Gist”: Low-viscosity, high-potlife 2-component systems useful for the production of composites are prepared from a polyol and isocyanate component characterised only in that polyol and iso are immiscible (case 1) or that the di-iso contains an amount of uretonimine (case 2).

Why it is interesting: These are two rather strange cases. The claims are very wide and the only ‘inventive step’ for the WO-32 case is that iso and polyol are chosen such that they are incompatible and phase separate after mixing as evidenced by the mixture becoming turbid. The inventive step in the WO-34 case is that the isocyanate is based on 2,4′ and 4,4′ MDI of which 3-25% (of the NCO) has been converted to uretonimine. Advantages mentioned are low viscosity, long potlife (open time) and a high Tg after crosslinking. In the examples a polyol/iso mixture is shown with an NCO index of 120, resp 150 without any catalyst or another additives. The ‘surprising effect’ in this invention is not immediatly clear to me and judging from the number of “X”-es in the search report the claims will most likely not get granted as such.

Carbon Fibre Composite

Innovation in Polyurethanes

All posts in category composites

Hybrid Polyurethane-Epoxy Pultrusion System

Polyurethane Prepregs prepared with Isosorbide

Low Viscosity Systems for Fibre-Reinforced PU Composites

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