Iowa Paint Manufacturing Co.Viscosity Analysis

Presented By:

Ruchi Patnaik

Co-Author:

Piyanka Roy

Iowa Paint Manufacturing Co.

• Since 1933, Iowa Paint has been making quality paint and coatings

• More than 1400 colors available

• The choice of professional painting contractors for quality paints

• Paints and coatings meet and/or exceed U.S.Government paint specifications

Satin Acrylic House Paint

• Very durable for interior walls and ceilings

• Good color retention

• Easy water clean-up

• Low odor

• Dries to tough finish

• Rooms can be used almost immediately

Objective

• Improve viscosity for batches of paint

– Determine precision of viscosity measurements (and identify removable sources of imprecision)

– Find the appropriate quantity of Hydroxyethyl Cellulose (HEC also known as A44) to be added for various desired adjustments of viscosity

Viscosity

Viscosity of paint is increased or decreased by addition or removal of the following three elements

• A44 (Hydroxyethyl cellulose)

• T49 (Water)

• Resin

Current Situation

• Low initial incoming viscosity

• Final viscosity requirement: 95-100 Krebs

• Use of A44 to increase viscosity

• Paint produced in 2000 or 4000 gallon tanks

• Use of trial and error to get to desired viscosity

Why A44?• High thickness efficiency• Low water solubility• Excellent color development and color acceptance• Compatibility with a broad range of paint

ingredients• Batch-to-batch uniformity• Good brush and roller application• Non-sagging properties

Analysis

• Gage R&R study for lab measurement precision

• Homogeneity test for within vat sampling variance

• Regression Analysis

Gage R&R

• Repeatability is variation typical of that seen in repeat measurements for a particular operator on a particular specimen

• Reproducibility is variation that can be attributed to differences between operators

Gage R&R

• Two different batches of paint

• Two measurements by each of 4 group members for each batch

• Use of viscometer and stop watch to measure viscosity

• Viscosity measured at 77Fahrenheit

Gage R&R DataBatch #98J 045 Batch #98K005

Operator Viscosity Operator Viscosity1 95 1 991 95 1 992 96 2 992 95 2 993 95 3 993 95 3 994 96 4 994 96 4 99

R&R CalculationsEquations for repeatability and reproducibility:

^ ^

MSEityrepeatabil

MSE

mMSABIMSB

mIilityreproducib

11

1,0max

Source DF SS MSParts 1 52.5625 52.5625 MSAOperators 3 0.6875 0.2292 MSBInteractions 3 0.6875 0.2292 MSABError 8 0.5000 0.0625 MSETotal 15 54.4375

I (parts) = 2 J (Operators) = 4 m = 2

Within-Vat Sampling

• Five samples from one batch of paint

• Two measurements by each of 4 group members for every sample

• Use of viscometer and stop watch to measure viscosity

• Viscosity measured at 77° Fahrenheit

Within-Vat DataSample

#1 #2 #3 #4 #51 101 100 101 100 1011 102 100 101 99 1022 101 100 102 99 1032 101 101 100 99 1023 102 100 101 100 1023 101 101 101 99 1024 101 100 100 99 1024 101 101 101 100 102

Operator

Within-vat CalculationsEquations for locations:

^

MSE

mMSABJMSA

mJlocations

11

1,0max

Source DF SS MSLocations 4 30.850 7.713 MSAOperator 3 0.275 0.092 MSBInteraction 12 2.350 0.196 MSABError 20 7.500 0.375 MSETotal 39 40.975

Results of Measurement Precision Studies

Gage R&R Calculations

• repeatability = 0.250 Krebs

• reproducibility = 0.327 Krebs

To combat reproducibility variation, keep operator fixed

^

^

Results of Measurement Precision Studies

Within-Vat Calculations

• repeatability = 0.612 Krebs

• locations = 0.922 Krebs

To account for location variation, sample from several locations and either physically mix, or average measurements

^

^

Historical Data

Sample A44added

Viscosity Sample A44added

Viscosity

1 0.00 91 6 0.00 881 6.25 102 6 6.00 962 0.00 92 6 7.50 982 6.25 100 7 0.00 863 0.00 93 7 10.00 1003 5.00 100 8 0.00 894 0.00 91 8 7.50 964 6.25 98 9 0.00 905 0.00 85 9 7.50 955 10.00 97 9 9.50 97

46

Historical Data

84

86

88

90

92

94

96

98

100

102

104

0 2 4 6 8 10 12

A44 Addition (lbs/1000gal)

Me

as

ure

d V

isc

os

ity

(K

reb

s)

•Plot of all nine samples in order to examine the slope

Regression Analysis

• Use of Minitab software to find relationship between amount of A44 added and mean viscosity increase

• Equation found is in terms of:– Add ‘x’ pounds of A44 in every 1000 gallons of

paint to increase viscosity by ‘y’ Krebs

• Minitab output for regression analysis gave 1.19 lbs. of A44 additive to be added to 1000 gallon tank for 1 Kreb increase

Regression Output

The regression equation is:

visc = 87.3 + 1.19 added + 5.51 z1 + 5.01 z2 + 6.25 z3 + 3.51 z4 - 2.21 z5 + 1.38 z6 - 0.21 z7 + 0.77 z8

For i = 1,2, … , 8

zi

otherwise 0

i sampleon ist measuremen if 1

Derived Equations

• For 1000-gallon tank: y = 1.19 * x

• For 2000-gallon tank: y = 1.19 * 2x

• For 3000-gallon tank: y = 1.19 * 3x

• For 4000-gallon tank: y = 1.19 * 4x

Equations were derived for each size of tank used by Iowa Paint, where

y = pounds of A44 & x = desired viscosity increase (Krebs)

Viscosity Table

Desired Increase (Krebs) A44/1000 gal A44/2000 gal A44/3000 gal A44/4000 gal1 1.19 lb. 2.38 lb. 3.57 lb. 4.76 lb.2 2.38 lb. 4.76 lb. 7.14 lb. 9.52 lb.3 3.57 lb. 7.14 lb. 10.71 lb. 14.20 lb.4 4.76 lb. 9.52 lb. 14.20 lb. 19.04 lb.5 5.95 lb. 11.9 lb. 17.85 lb. 23.8 lb.6 7.14 lb. 14.20 lb. 21.42 lb. 28.56 lb.7 8.33 lb. 16.66 lb. 24.99 lb. 33.32 lb.8 9.52 lb. 19.04 lb. 28.56 lb. 38.08 lb.9 10.71 lb. 21.42 lb. 32.13 lb. 42.84 lb.10 11.9 lb. 23.8 lb. 35.7 lb. 47.6 lb.

Table for the amount of additive appropriate for various tank sizes

Viscosity PlotPlot of viscosity increase versus A44 addition for the 1000-gallon tank

0

2

4

6

8

10

12

1.19 lb 2.38 lb 3.57 lb 4.76 lb 5.95 lb 7.14 lb 8.33 lb 9.52 lb 10.71 lb 11.9 lb

A44 added

Vis

cosi

ty I

ncr

ease

(K

reb

s)

Conclusions•Several factors play a role in viscosity measurements

- One source of variation relates to measurements done by different people-Another relates to tank location of the sample obtained

• Historical data provides quantitative guidance for viscosity adjustment

Recommendations

•Make sure that only one person handles the viscosity measurement

•Samples for measurement of viscosity may be taken from different areas of paint tank and mixed or measurements averaged

•Use the equations, table and chart derived from historical data to eliminate trial and error (and get correct viscosity)

Aftermath•Company is willing to try it out!

•Able to give the company an acceptable solution to implement

•Derived accurate amounts of Hydroxyethyl Cellulose to add to achieve desired viscosity level

•Graphical and tabular representation of solution for easy reference

Acknowledgements

• Dr. Stephen Vardeman

Professor

Iowa State University

• Mr. Mark Angerer

Technical Director

Iowa Paint Manufacturing Co.

Questions?