All posts in category Rigid Foams

Polyurethane OCF Systems with Low Monomeric Isocyanate Content

Title: IMPROVED POLYURETHANE FOAM COMPOSITION

 Number/Link: WO2013/072380

Applicant/Assignee: SOUDAL

Publication date: 23-05-2013

“Gist”: Use of mono-alcohols to reduce monomeric isocyanate content in OCF systems.

Why it is interesting: OCF , or one component foam (or froth) systems are isocyanate ended prepolymers, mixed with organic blowing agents and other additives like catalysts. They are often prepared directly into pressure cans and are mostly used in construction as adhesives and sealants.  Curing happens by reaction with ambient moisture. Recent changes in legislation has forced OCF producers to drop the amount of free monomeric isocyanate in their systems.  In this invention OCF systems with less than 1% free monomeric MDI are produced by reacting a conventional diol, a polymeric/monomeric MDI mixture and a relatively low MW monol (2-ethyl-hexanol in the examples).  The monol allows to produce prepolymers with low NCO content and low free MDI by preventing chain extension and therefore avoiding extreme viscosity build-up.

OCF system in pressure can.

OCF system in pressure can.

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by Gerhard Bleys on May 28, 2013  •  Permalink
Posted in Adhesives-Coatings, Rigid Foams
Tagged , ,

Posted by Gerhard Bleys on May 28, 2013

https://purpatents.com/2013/05/28/polyurethane-ocf-systems-with-low-monomeric-isocyanate-content/

Hybrid PU-PF Rigid Foams

Title: RIGID POLYURETHANE FOAM

 Number/Link: EP2591034A1

Applicant/Assignee: BASF

Publication date: 15-05-2013  (priority PCT/EP)

“Gist”: Use of novolac polyols in rigid (spray) foams to improve reactivity and flammability properties.

Why it is interesting: ‘Novolacs’ are phenol-formaldehyde (PF) resins which are produced at a p:f ratio of  >1 (as opposed to ‘resols’ where this ratio is <1) Novolacs are therefore phenol (OH) ended and can be used together with isocyanates to prepare hybrid polyurethanes. In this case novolacs with a functionality of about 4-8 are used together with conventional rigid foam polyol(s) in which the novolacs are dissolved (after heating and opt. melting) in an amount of about 40%. Together with polymeric MDI, water and conventional additives rigid (spray) foams are produced with improved flammibility, smoke, scorching and reactivity properties.

Novolac resin

Novolac resin

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by Gerhard Bleys on May 22, 2013  •  Permalink
Posted in Rigid Foams
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Posted by Gerhard Bleys on May 22, 2013

https://purpatents.com/2013/05/22/hybrid-pu-pf-rigid-foams/

Rigid Polyurethane Foam With Very High Amount of Fillers

Title: MEDIUM DENSITY FOAMS HAVING GOOD IMPACT RESISTANCE AND A PROCESS FOR THEIR PRODUCTION

 Number/Link: US2013072588

Applicant/Assignee: Bayer

Publication date: 21-03-2013

“Gist”: Up to 80% of a mixture of glass fibers and other fillers is incorporated into rigid foam to improve impact resistance.

Why it is interesting: Use of fillers in PU foams is well known but the amounts are usually limited to about 20% w/w. In this case 10-30% of glass fibers with a fiber length of about 25mm is used together with 30-60% of particulate fillers.  In the examples ammonium polyphosphate is used together with calcium carbonate and glass fibers.  Foam density ranges from 150 to about 350 kg/m3.  Bayer claims an improved impact resistance.  Other mechanical properties are not given.

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by Gerhard Bleys on March 27, 2013  •  Permalink
Posted in composites, Rigid Foams
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Posted by Gerhard Bleys on March 27, 2013

https://purpatents.com/2013/03/27/rigid-polyurethane-foam-with-very-high-amount-of-fillers/

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