Perfume‐containing polyurea microcapsules with undetectable levels of free isocyanates

Abstract

Core-shell polyurea microcapsules with a 40% fragrance load were prepared by interfacial polymerization of guanidine and a technical polyisocyanate prepolymer containing mainly the biuret trimer derived from hexamethylene di-isocyanate (HDI). Residual free polyisocyanates were still present at a level slightly above 100 mg NCO functional group per kg as determined by liquid chromatography hyphenated with tandem mass spectrometry of HDI and of its biuret trimer. This level was decreased by a factor of about 10 when the polymerization process was allowed to proceed for a longer time and by a factor of about 500 when guanidine or NaOH were added to the microcapsule suspension to act as scavengers. In these cases, polyisocyanate conversion was observed to proceed for about one month when the microcapsules were stored at room temperature before reaching a plateau at a level below 1 mg NCO/kg. Overall, ammonia was the most efficient polyisocyanate scavenger as no residual HDI biuret trimer and only less than 2 lg NCO/ kg as HDI were detected at the end of the process, a level which had dropped below the limit of detection of 0.25 lg NCO/kg after about 40 days of aging at room temperature.

Determination of the shell permeability of microcapsules with a core of oil-based active ingredient

“…One of the many industrial applications of microcapsules is their application to fabric care (Nelson, 2002;Ma et al, 2009;Miro Specos et al, 2010), particularly in respect to the encapsulation of perfumes and fragrances (Jacquemond et al, 2009;Rodrigues et al, 2009;Feczko et al, 2010;Sansukcharearnpon et al, 2010). Microcapsules containing a core of perfume can significantly increase the amount of perfume that remains attached to the fabric after a washing cycle, and so less perfume is required within the formulation in order to offer the same pleasant scent, and additionally the release can be triggered by a mechanical force generated by, for example, rubbing .…”

Core–shell nanocapsules containing essential oil for textile application

“…[6][7][8] Currently, nanoformulation is considered as a better choice for fragrance encapsulation in textile treatments, since the material's nanometer size can provide a strong adhesive force and interaction with the fiber due to the material's large surface area. [14][15][16][17][18][19] Core-shell polymers typically consist of two polymeric walls, one wall has a low glass transition temperature, and the other with a high glass transition temperature. [9][10][11][12] Nano-essence capsules must have proper properties to be a suitable essence capsule for cotton textile treatment.…”

Fragrance‐Containing Microcapsules Based on Interfacial Thiol‐Ene Polymerization

“…In the industry, the majority of commercial fragrance microcapsules consists of poly(urea–formaldehyde), poly(melamine–formaldehyde), polyurethane, or polyurethane–urea shell materials because of their superior thermal and mechanical properties and readily available and cheap monomers . However, to minimize the amount of residual monomers including isocyanate, melamine, and formaldehyde, prolonged reaction time, elevated temperature, and scavenger molecules are frequently required and lead to higher cost . Therefore, exploring new types of chemistry with improved feasibility and reaction efficiency for the development of polymeric microcapsules is of fundamental importance in fragrance applications.…”