• Color
• Physical Properties
• Particle size/dispersion

Currently a sample is taken and tested off-line to check these characteristics. If the specifications are not met, repeated adjustments and sampling are necessary until the specifications are met. Technology has advanced over the years and the testing time has been reduced. However, still all of the testing is done in the laboratory.

If the testing and adjustments can be done while the product is being produced and/or applied the manufacturing time will be significantly reduced. Manufacturing operations using such a technology are and will realize significant benefits. They are:

• Improved profitability
• Consistent quality between each manufactured unit irrespective of the production site

Current Technology:

In the manufacture or application of a colored liquid, a sample is drawn and tested off-line for color and other properties. Depending on the product to be manufactured, generally color is read by mixing a standard quantity in a known standard white base sample, a dry film is produced and its reflection is measured. It is compared against the product standard, and adjustments, if necessary are made. Other characteristics are checked and adjusted. Sampling and adjustments are done until all the specifications have been met. Once the product meets specification, no additional testing is done. It is expected that product will not change during packaging or consumption. This may or may not be true.

New Technology:

Our technologies allow one to measure and correct the properties and specifications as the colored liquid is being produced. The first generation technology is Reflection only technology and is called the Colorcell Technology. The second generation technology is Reflection and Transmission technology and is called Multicell Technology. We will discuss the Multicell technology in detail.
In this technology, the fluid whose characteristics are to be checked and corrected is passed between two parallel plates. One plate is fixed and the other plate moves to create a thin film between 20 to 3000 microns. A white light passes through the film. The light transmission through the liquid film is read by a spectrophotometer.

The cell has two wipers that continuously clean the glass ports so that there is no film build up. Figure 1.

Since each color has its unique absorption at different wavelength, the optimum light transmission is read at various film thicknesses. A unique fingerprint is created for each liquid. Once a fingerprint is created, it can be matched by varying and controlling the quantity of components that produce the liquid.

The cell also rotates on its axis by certain angle and reads the reflected light to read reflective properties.

The two technologies are being used and/or evaluated in different industries. Figure 3.

Since the technology uses white light vs. standard white base (current method), the element of human variation and error and any variation due to raw materials for the white base is eliminated. Figure 4.

Renner Herrmann S. A. Brazil has developed the technologies. They are patented and being licensed. Figure 5.

The Reflection and Transmission technology significantly improves profitability as it:

• Improves quality.
• Reduction of manufacturing time.
• Reduced Raw material and Finished Goods inventories.
• Reduced time to market.

Profitability improvement can be about 15-25%. The technologies can also be retrofitted in the existing plants giving a very high return on investment.

Application:
The Multicell or the Colorcell technology is easy to apply in a manufacturing facility.

Figure 6 shows a simplified schematic of the cell as it is applied to a manufacturing operation.

Various liquids that constitute the product are metered in a specially designed Mixer. A large portion of the liquid after mixing goes to a Recycle Tank. The remainder, a small portion, of the mixed liquid is passed through the Cell and its characteristics are read and compared to the internal standard. The software adjusts and controls the flow of the liquids to the Mixer and the Cell takes continuous readings. As soon as the product meets it specification, the liquid going to the Recycle Tank is diverted to its final destination. As long the liquid is being produced, the flow of the small portion of the mixed liquid going to the Cell does not stop. All of the liquid in the Recycle Tank and the Mixer is good product and their flow is controlled so that at the end of production run essentially very little or no liquid is left in the system.

After the desired quantity of the product has been produced the whole system is cleaned in about 2 to 4 minutes and is ready to produce another product. The cell can be also used to monitor and control the dispersion process by passing the liquid through the cell as it is dispersed. Viscosity and density are also monitored and controlled to meet specifications.

Since the manufacturing is monitored continuously, only QUALITY is produced. No re-work is produced and waste is minimized. Since the factory is producing quality, the factory can be operated on "JUST IN TIME" mode. Either technology can be used in batch or continuous mode.
These technologies can also be used in the product development as the formulation and testing time can be significantly reduced. Current trends and market needs can be very quickly addressed.

Test result examples:

The attached figures and tables show some of the test results using the Reflection only and Transmission and Reflection technology.

The table 1 shows the composition of 6 kaolin samples. Different compositions affect yellowness and whiteness of the samples.

Since we can differentiate between samples, it is possible to control the color of the Kaolin slurry as it is being produced. Figure 7 and 8 respectively compare the measurement of the different samples of Kaolin using conventional and wet reflectance by Colorcell. The colorimetric behavior of the two Kaolin measurements (conventional versus wet) is similar. This allows in-line process control and production. Cost and quality are optimized.

Figures 9, 10, and 11 show the applicability of the Multicell measuring absorption without dilution of a dye used in wood coating. Two samples, standard and batch (standard + 1% orange dye) were analyzed using conventional draw down methodology and the Multicell system. The conventional method needs a highly diluted sample (about 1 to 0.0001 proportion) and is measured using a 10 mm cuvette. The Multicell used a path length of 20 microns to measure the sample in its natural state (without dilution). Since we can measure and control product quality without dilution, we can effectively produce product of consistent and higher quality at lower cost.

Figure 9 shows the reflectance of the samples using conventional dry measurement. Figure 10 shows the transmission of the samples measured by Multicell at 20 micron.

Figure 11 shows the transmission of the samples using the conventional equipment (diluted) and a 10 mm cuvette.

The K (absorption coefficient) for the two samples calculated by the equation:

T = e-K*C*X Where: T = Transmittance C = Concentration X = Path length thickness K = absorption coefficient

Figure 12

Figure 12 shows the relationship of the two K coefficients. The similarity indicates that the Multicell technology results are similar to the conventional methods but are accurate and obtained quickly resulting in higher profitability.

The Table 2 shows an iteration that was needed to match a colorant. Start point and the first iteration are listed.

Figure 13

Figure 13 graphically shows the results. The speed and accuracy achieved over conventional methods is very high and reproducible. This allows improved product quality and profitability.
We believe that the technologies presented are applicable to the industries outlined and can benefit companies involved in these businesses by improving their profitability and product quality.

REFERENCES
1. Rogério A., Peixoto C. A. L. "Breakthrough in the paint industry" European Coatings Journal 738, October 1998
2. Malhotra G. "Continuous vs. Batch Manufacturing" Paint and Coatings Industry 100, February 1999
3. Malhotra G. "The Coating Industry' s Challenge for the New Millennium" Modern Paint and Coatings 60, October 1999
4. Pfeil P. R. "Tinting strength adjustment using Light Transmission" Paint and Coatings Industry 76, April 2000
5. Malhotra Girish, Peixoto C. A. L., Pfeil P. R., Schotgues E. "The Color of Money: New technology helps improve coatings production efficiency and profitability" Modern Paint and Coatings 22, February 2001

7th Nürnberg Congress XII.3, April 7-8, 2003

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