Eastman cellulose esters in cast acrylic sheetBetter appearance and productivity

ADD-COAT-7953

Content

Segment overview Challenges addressed by CAB Testing CAB Conclusion

Segment overview

Importance of cast acrylic sheets

Cast acrylic sheets work well in applications that requirewater resistance, outdoor durability, and UV resistance.

Bath tubs and shower cubicles

Outdoor signage

Display shelves

Challenges addressed by CAB

Challenges with production of cast acrylic sheets Flooding and floating

FloodingThe tendency of pigment particles to rise to the

surface during drying/curing and produce a uniform surface color that is different from the rest

of the material.

FloatingThe tendency of pigment particles

to separate and concentrate in particular areas, resulting in an uneven color distribution,

also on the surface.

Eastman cellulose esters in cast acrylic resinsCombat flooding and floating

Eastman CAB enables a more efficient process delivering a higher quality product.

CAB improves appearance and productivity during production

Reduces flooding and floating of carbon black

pigment in gray cast acrylic sheet

Produces a more uniform color

Lowers production costs with reduction of rejects

Testing CAB

Formulation of cast acrylic sheet

Ingredient Description Standardweight%

With CABweight%

Methyl methacrylate syrup Polymerized less than 8% 98.85 97.35

VAZO® 641 Initiator/catalyst 0.04 0.04

Tinuvin™ P2 UV absorber 0.03 0.03

Aerosol® OT-1003 Demoulding agent 0.03 0.03

Eastman CAB-381-204 Pigment dispersion additive - 1.5

White pigment paste 60% TiO2 (Bayer titan R-FK2 5) + 40% DIBP plasticizer 1.0 1.0

Black pigment paste 20% Special Black® 100 6 + 40% DIBP plasticizer 0.05 0.05

Coloured syrup is pumped between two large glass sheets. Clamped and polymerized via heat.

1 Chemours, 2 BASF, 3 Cytec 4 Eastman Chemical, 5 Huntsman, 6 Orion Engineered CarbonsNote: Eastman™ CAB-381-0.5 is recommended when the Methyl Methacrylate Syrup is polymerized to higher than 8%. In this example the polymerization level was less than 8% and consequently CAB-381-20 was used.

Design of experimentPreparation of the cast acrylic sheet

Methyl methacrylate monomer (MMA) polymerized (approximately 85°C) with an initiator to less than 8%, producing a low viscosity syrup.

UV absorber, demoulding agent, pigment paste, and Eastman cellulose acetate butyrate (CAB-381-20) added to the syrup.

De-foamed at full vacuum. The de-foamed coloured syrup was pumped between two large glass sheets. A PVC seal is used around the edge of the glass sheets to control the thickness of the

gap between the sheets. The PVC seal also prevented the syrup from escaping. Polymerised in water to 90% @ 65°C for 200 minutes. Polymerised in oven at 125°C for 120 minutes to complete the cure to 100%. The glass sheets removed. Acrylic sheet was cut via automatic saw to the required dimensions. Protective sheet applied. The sheets were then evaluated for color differences.

Without Eastman CAB With 1.5% Eastman CAB

Front surface

Comparing appearanceWith and without Eastman CAB

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Without Eastman™CAB With 1.5% Eastman™ CAB

ΔE

Without Eastman CAB With 1.5% Eastman CAB

Colour differences (DeltaE) – Test method ASTM E1164-2 7

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Superior appearanceWith Eastman CAB

Eastman cellulose acetate butyrate sheets showed:• Improvement of metallic flake and pearlescent flake alignment.• Reduction of extender haziness or clouding, particularly with barium

sulphate.

Without CAB With CAB

The sheet with Eastman CAB has a noticeably better appearance

Conclusion

Benefits of Eastman CAB in cast acrylic sheet

In this test, Eastman CAB appeared to• Eliminate flooding and floating of colored pigments.* • Reduce titanium dioxide sedimentation during polymerization, allowing for

uniform distribution of titanium dioxide throughout the cast sheet.*

Various grades of Eastman cellulose acetate butyrate have also demonstrated

• Improvement of metallic flake and pearlescent flake alignment.• Reduction of extender haziness or clouding, particularly with barium

sulphate.*

*Theorized to be the result of the CAB reducing the agglomeration of pigments and extenders

Eastman CAB can improve appearance and productivity

More technical information

More information on Eastman cellulose esters and the technical tip related to this presentation (CE-EU-COAT-3050) can be found on www.eastman.com

Disclaimer

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