All posts tagged compression set

Temperature Stable Memory Foams

Patent Title: VISCOELASTIC POLYURETHANE FOAMS WITH REDUCED TEMPERATURE SENSITIVITY

Number/Link: WO2018/169833

Applicant/Assignee: Covestro

Publication date: 20 September 2018

“Gist”: A polyol blend comprising a relatively low-EO monol, diol and triol is foamed with TDI

Why it is interesting: Viscoelastic or “memory” foams are popular materials for pillows and mattresses. One drawback of these materials is the sensitivity of hardness to room temperature variations. According to this invention the hardness variations can be reduced by preparing the foams form TDI and a polyol blend comprising a monofuntional polyether with an EO content of less than 20%, a polyether diol and a polyether triol both with an EO content of less than 45% together with water, catalysts and other additives. The polyol blend can optionally be made in situ. The foams show an E'(15°C)/E'(30°C) ratio between 1 and 4, a Tg of less than 20°C (defined as the temperature of max. tanδ), together with high air flow and tear strength values.

DMTA trace of foam according to the invention

Catalyst System for Frothed Foams

Patent Title: METHOD FOR DELAYING CURING IN POLYURETHANE AND COMPOSITIONS AND ARTICLES MADE THEREFROM

Number/Link: WO2018/075302

Applicant/Assignee: Rogers

Publication date: 26-April-2018

“Gist”: A mixture of a metal acetylacetonate and a catalytic inhibitor prevents premature curing

Why it is interesting: A catalyst system that prevents premature curing of frothed (PORON® – type) foams consists of ferric acetylacetonate catalyst and a β-diketone inhibitor e.g. acetylacetone or dibenzoyl methane. The catalyst combination allows for handling of the raw materials at 55°C for 5 minutes without reacting. Frothed foams tend to have improved properties, like compression set as compared to conventional foams.

Tris(acetylacetonato)iron(III) (Wikipedia)

Flexible PU Foams Containing Latent Aldehydes

Patent Title: IMPROVEMENTS RELATING TO POLYURETHANES

Number/Link: WO2017/001543

Applicant/Assignee: Shell

Publication date: 5 january 2017

“Gist”: Flex foams from polyether polyols containing latent aldehydes show improved compression set

Why it is interesting: Aldehydes are a by-product of the alkylene oxide production. These aldehydes need to be removed before the alkylene oxide can be used in the manufacture of polyether polyols because even minor amounts of these impurities are considered undesirable and detrimental for polyol and foam properties. According to this invention, omitting the extra purification step of the alkylene oxide results in polyols with a certain amount of free- and latent aldehydes. (‘latent aldehyde’ being an aldehyde incorporated in the polyether polyol with a labile bond). After removal of the free aldehyde, the polyols with (pref) >150ppm latent aldehydes (mostly propionaldehyde and acetaldehyde) can be used in the preparation of flexible foam with improved wet and dry compression set properties. While the examples indeed show some (but not a dramatic) improvement of compression set, no mention is made of eventual release of the aldehydes in the atmosphere, which (in my opinion) is a much bigger problem than compression set.

Propionaldehyde

Innovation in Polyurethanes

All posts tagged compression set

Temperature Stable Memory Foams

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Catalyst System for Frothed Foams

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Flexible PU Foams Containing Latent Aldehydes

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