for examining the coating color and base paper interactions

A method for coating color optimization with the emtec PDA.C 02 - developed by Gruener and Baumeister -

• Characterization of the coating base paper surface
• Defined coating color preparation
• Simulation of the coating machine applicators at the time the coating color and the base paper are contacted :
  • Simulating the shearing history of the coating color in the coater
  • Dynamically contacting the coating color with the base paper
  • Producing a high shear impulse and pressure pulse
• Characterization of the coated paper
• Instantaneous measurement within approx. 39 msec of contact
• Simple evaluation of the measuring results

What are the benefits of the measuring method?

• Differences in base papers, coating colors and coated papers lead to quality changes during processing ; unfortunately, the classical measuring methods do not adequately detect these variations.
  The PDA.C 02 system is able to identify these differences.
• Pilot coater and machine trials indicate the effects of coating color and base paper variations.
  The PDA.C 02 provides a tool to explore the origins.

The PDA.C 02 can measure all three stages of the coating process :

1. Base paper

• Assessing process relevant surface quality parameters
  such as surface porosity, surface sizing and fines/filler concentration at the surface
• R & D: Optimizing the base paper, developing new grades, ensuring quality consistency of several rolls in coating trials
• QC: Detecting slight quality variations during production

2. Coating color in contact with base paper

• Reducing the need for pilot coater / machine trials
• R & D: Visualizing the interactions between the coating and substrate surface, gaining new insights, optimizing the additive and pigment use ( types and dosages )
• QC: Controlling the incoming quality of additives and pigments
• Assessing the changes in runnability, coating hold out, covering and print evenness in offset and flexo printing

3. Coated paper

• Assessing the surface quality of coated papers :
  • Identifying small changes in the coating quality by comparing measurement results of liquid penetration with suitable test liquids ( water or mineral oil )
  • Determining and predicting the properties such as printability, glueability or barrier effects on the basis of a database or process analysis

Measuring method
R & D : Modelling of the processes and the coating color to base paper interactions
Characterizing the base paper by measuring with water, carboxyl methyl cellulose solution and serum
Preparing and deaeration the coating color with a CDA / CDM laboratory system, taking the relaxation times after shear loads into account
Measuring the coating color to substrate interactions with the PDA.C 02 in the short term time range, simulating the coating machine applicators
Evaluating the measuring results with the aid of the "Cookbook" for coating color optimization: Calculating the immobilization time IT Determining the curve gradient signs +/- Determining the gradient magnitude until FC Noting the curve shape after DWRV Information is provided concerning the homogeneity, structure, thickness, density of the immobilized filter cake, runnability of the coating color, print evenness, coating hold out and covering.

Measuring principle

A base paper sample is fixed on a sample holder and injected into an adjustable measuring gap filled with coating color.This causes dynamic contact between coating color and base paper, as well as a high-shear and pressure impulse. As the sample reaches its final positon, high frequency ultrasound is transmitted through the paper in the Z-direction.The liquid penetrating into the paper and alters the paper's ultrasound transmission in a characteristic manner. This ultrasound alteration is recorded as an intensity-time diagram, using a PC. Additionally, the penetration of other liquids into base paper or coated paper can be measured in a standard measuring cell, without the shear gap, applying the same measuring principle.

Technical data
	PDA.C 02 - Measuring Device Testing liquids: Coating color, water, mineral oil, inorganic and organic liquids with low to medium viscosity Paper and board: up to approx. 600 g/qm Mains voltage: 110 V 60 Hz / 220 V 50 Hz Weight: approx. 19 kg 8 different contact programs
	SFK Coating Color Measuring Cuvette Shear gradent: approx. 1.000 to 40.000 s-1 Pressure impulse: approx. 1,5 to 2 bar / < 10 msec Contact speed: approx. 2 m/sec Shearing gap: approx. 50 μm bis 2 mm
	CDM Coating Color Deaeration and Mixing System Amount of coating color: up to 1,5 l Air content of the prepared coating color: < 1 % Speed range of the mixer / disperser: approx. 600 to 10.000 min-1 Working principle: Rotor - stator Mains voltage: 110 V 60 Hz / 220 V 50 Hz Weight: approx. 22 kg
	CDA Coating Color Deaeration System Amount of coating color: up to 1,5 l Deaeration efficiency: approx. 90 % depend on coating additives Working pressure: 50 bis 75 mbar Mains voltage: 110 V 60 Hz / 220 V 50 Hz Weight: approx. 9 kg

Attachments:

Coating Prospekt	[deutsch]	485 Kb
Coating Leaflet	[english]	486 Kb