Rubber Gloves - Importance of Measuring Fillers Brightness
Latex compounding is one of the most important process in glove manufacturing. At this stage, compounding ingredients such as stabilizers, vulcanizing agents, accelerators, activators and color pigments are added in latex compound. The addition ratios of these chemicals is critical to achieve optimum physical properties as well as desirable color and appearance in the final glove products.
One of the key ingredients used is inorganic filler. It is used to reinforce latex properties and serve as a tinting base.
The choice of filler will make a big difference in the way a latex compound will be colored. The best color is produced using clean fillers like silicate which are typically more expensive. Lower grade fillers like kaolinite clay can be made into fairly bright colors by using a lot of titanium oxide (Ti02) and higher colorant levels but often result in higher cost. Nowadays, non-black fillers such as precipated or grounded calcium carbonate is widely used in latex compound as shown in Figure 1.
Brightness Index Explained
Brightness is generally defined as the percentage reflectance of blue light at wavelength 457nm. This measurement was introduced as a rapid test for controlling the degree of bleaching and it is based on the amount of blue light emitting from the substrates.
This index measurement do not have any connection with any color and in particular with the perceived whiteness.
Referring to Figure 2, the Blue curve shows ISO Brightness at 100 which measuring the diffuse blue reflectance factor only and it is not related to the perceived whiteness.
The Red and Grey curve respective shows BISO at 79.7 and 74.2 but both overall reflectance factor is better resulting in higher perceived whiteness.
Brightness in filler provides an excellent measure to the maximum whiteness that can be achieved with proper tinting.
Brightness Index Measurement
ISO Brightness R457 is a general index used for brightness measurement. It is measured with a reflectometer having the characteristics described in ISO 2469, equipped with a filter (when colorimeter is used) or corresponding function having an effective wavelength of 457 nm and a half-peak bandwidth of 44nm (when spectrophotometer is used).
ISO Brightness R457 can be measured using any instrument geometry. The common standards for Brightness measurement with its corresponding geometry as illustrated in Figure 3.
What Measurement Solutions Can Konica Minolta Offer?
The CM-5 bench-top spectrophotometer is a versatile color measuring instrument capable to measure samples in many forms such as pellets, solids, gelatins, powders, pastes and liquids.
With its top-port design, it is ideal for evaluating color indices of fillers, particularly the ISO Brightness. Furthermore, the petri dish accessory enables measurement of fillers in powder and slurry form.
Contact us for a free consultation with our application specialists and let us assist you on your color and appearance measurement needs.
