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Color-cure indicator for 2K polyurethane adhesives

IP.com Disclosure Number: IPCOM000248883D
Publication Date: 2017-Jan-19
Document File: 3 page(s) / 206K

Publishing Venue

The IP.com Prior Art Database

Abstract

A color changing cure indicator into fast-curing two component (2K) reactive polyurethane adhesives is herewith disclosed. A dye-based color indicator helps to indicate mixing quality and point-of-cure for fast curing 2K polyurethane adhesives. The identified solution of a direct color indication of the mixing quality and curing degree for fast-curing 2K polyurethane (PU) adhesives is a pH indicating dye commonly known as bromophenol blue. Two applications, where the visual indication of cure progression is meaningful, is for one equestrian hoof repair and for the other the rapid reattachment of broken plastic parts in automotive aftermarket applications.

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Color-cure indicator for 2K polyurethane adhesives Introduction: Two component (2K) reactive polyurethane adhesives are commonly used for a large variety of applications since several decades. They are typically composed of 2 initially separated parts, referred to as an isocyanate containing part A and a polyol containing part B. By mixing both parts together a curing mechanism is activated, resulting in the finished products after complete cure. However, the actual chemical reactions are often still little understood nowadays. As the chemistry of these reactive systems additionally demands for a precise and homogeneous mixing process, it is important to fulfil this requirement through utilizing & developing very accurate application systems, in order to ensure the forming of long-term durable bonds in target applications. In some specific bonding applications it would also be found very helpful to visualize the mixing and curing reaction of the 2K polyurethane adhesive system itself, in order to help reduce e.g. the fixing time during assembly manufacture and hence, increase productivity. For these kind of bonding applications a color changing cure indicator, as part of the 2K polyurethane adhesive system, is a good attempt to solve the need for visualization. Color Changing Cure Indicator for 2K reactive adhesive polyurethane systems A solution to implement a color changing cure indicator into fast-curing 2K polyurethane adhesives is herewith disclosed. The dye-based color indicator helps to indicate mixing quality and point-of-cure for fast curing 2K polyurethane adhesives such as commercially available as 3M™ Superfast® 55045 or 3M™ SMC/FRP Repair 1 08270. Two applications, where the visual indication of cure progression is meaningful, is for one equestrian hoof repair and for the other the rapid reattachment of broken plastic parts in automotive aftermarket applications. In hoof repair or hoof reconstruction, the animal needs to be immobilized, which is stressful for the animal. Therefore, if the time needed to finish the repair can be minimized, the impact on the animal’s health and its stress level can be reduced. For Automotive Aftermarkets repair and/or reconstruction applications the visualization of the curing degree indicates the point at which the adhesive mass can no longer be manipulated without breaking the freshly produced part. The identified solution of a direct color indication of the mixing quality and curing degree for fast- curing 2K polyurethane (PU) adhesives is a pH indicating dye commonly known as bromophenol blue. This dye has a transition from bright yellow to dark blue in between a pH range of 3.0 and 4.5, which correlates well with the changes occurring during the mixing and curing process. It has to be mentioned, that the change of color is only attributed to the change of pH and therefore directly a result of the amount of accelerator blended into the isocyanate part of the adhesive. Hence it is NOT indicative...