Coil coatings Improving efficiency, enhancing aesthetics

Transcription

1 Coil coatings Improving efficiency, enhancing aesthetics Eastman cellulose esters ADD-COAT-7952

2 Table of Contents Segment Overview Slide 4 Segment Challenges Addressed by CAB Slide 7 Results Slide 9 Conclusion Slide 10

3 Content of this presentation This presentation describes how Eastman CAB can improve the performance, efficiency and aesthetics of coil coatings Introduction coil coatings Eastman CAB improves properties: Metallic and pearlescent flake alignment Flow and levelling Gloss consistency in semi-gloss formulations Pigment dispersion Appearance in PVDF formulations

4 Segment Overview

5 What are coil coatings? Industrial process for coating metal A continuous, highly automated process Economical process due to high speed (200 meters per minute) A large coil of metal unwound, both top/bottom sides are cleaned, chemically treated (phosphated or chromated), primed, oven cured, top coated, oven cured again and rewound Pre-painted coils may be printed on and embossed to create special visual effects These coatings must be extremely durable while retaining excellent appearance.

6 What are coil coatings? Uses Coated metal is fabricated: Corrugated roofing, washing machines, filing cabinets, refrigerators/freezers, etc. Metals coated The metal coils are primarily steel and aluminium, but can also be hot dip galvanized, electro galvanized, zinc-nickel, stainless steel, brass and copper Coatings used The coating systems used vary. Polyester/melamine, polyurethane, epoxies, PVDF, PVC, and acrylics Environmental acceptance: evaporated solvents are incinerated and emissions meet legal requirements Coatings formulations must contain materials compatible with the coating process and deliver finished coating requirements for appearance and durability standards.

7 Segment Challenges Addressed by CAB

8 Key needs for coil market Coil coating producers require improved overall paint performance with minimal or no formula cost increase Better aesthetic appeal Semi-gloss systems with less variation in gloss levels Fewer surface defects for smoother finishes Purer white color Better paint coverage (yield) per square unit Improved productivity (increased line speed)

9 Results with Eastman CAB - Improved metallic and pearlescent flake alignment - Improved flow and leveling - Improved gloss consistency in semi-gloss formulations - Improved pigment dispersion - Improved appearance in PVDF formulations

10 Improved metallic and pearlescent flake alignment with Eastman CAB

11 Measuring metallic flake orientation Techniques 3D confocal microscopy Latest technology to scan surfaces Builds up a 3D profile of the coatings surface The roughness (RMS) of the surface is then calculated from the scanning measurements Multi-angled spectrophotometer (X-rite) Measures how well metallic/pearlescent flakes align by measuring reflection at different angels Measurements produce a flop index value - The higher the flop index the better the alignment

12 3D confocal microscopy analysis

13 Testing improved metallic flake alignment A polyester/melamine metallic formulation was prepared Formulations with and without CAB were prepared Applied on customers coil coating pilot plant Confocal and spectrophotometer measurements taken

14 Metallic coil coating Photographic confocal images Without CAB With 1% Eastman CAB Average flop index Average flop index With CAB, metallic flakes align flat and reflect more light, enhancing appearance

15 Metallic coil coating 3D projection through laser scanning confocal microscopy Without CAB With 1% Eastman CAB With CAB, metallic flakes align flat without areas of high peaks, achieving a smoother surface and more uniform appearance

16 Conclusions Without CAB Multitude of high peaks, indicating a rough surface. This system is of low brightness and visually is a dark, dullish, metallic colour with a grainy appearance. With CAB CAB containing system has far fewer peaks and large domains of flat areas. The cellulose acetate butyrate containing system has aligned the metallic flakes such that they are flatter and more even. This system is of high brightness and visually is a bright metallic colour with a non-grainy appearance. Eastman CAB can improve the metallic flake alignment and therefore the appearance of the coil coating

17 Improved metallic flake alignment Expected benefits to coil coater Improved metallic flake alignment and consistency from batch to batch Reduced "off spec" material Less customer complaints Less recoating, leading to more efficient and economical processing Brighter metallic and pearlescent coatings are more attractive to their customers

18 Improved flow and levelling with Eastman CAB

19 Testing improved flow and levelling A white polyester/melamine coil coating was formulated Systems with and without CAB were prepared 0.4% by weight of Eastman CAB was used Cured for 90 seconds at 250 C to reach a peak metal temperature of 250 C for 10 seconds Dry film thickness microns

20 Improved flow and levelling Pencil reflection Without CAB: Poor flow and levelling Less reflection, gloss value = 90 With Eastman CAB Good flow / levelling High reflection, gloss value = 94

21 Improved flow and levelling Flow and levelling additives level out any irregularities in the surface and tend to have minimal effect on surface tension Eastman CAB ensures that the coating remains smooth over the substrate after application and during curing Eastman CAB is beneficial in reducing and eliminating such surface defects as orange peel, crawling, craters, fish eyes, retraction, flooding and floating Elimination of surface defects produces smoother surfaces with higher gloss levels Eastman CAB can improve the surface uniformity of coil coatings, improving overall appearance.

22 Improved flow and levelling Expected benefits to coil coater Reduced "off spec" material Less recoating, leading to more efficient and economical processing Smooth, glossy coatings are more attractive to their customers Durability guarantees can be affected by poor flow and levelling

23 Improved gloss consistency with Eastman CAB in semi-gloss formulations

24 Improved gloss consistency Silica matting agents are often used to produce semigloss coil coatings Often problems in gloss consistency can occur in production The width of coil being coated can be 1.8 meters and obtaining a uniform gloss can be difficult

25 Testing improved gloss consistency A white polyester melamine formulation based on a silica matting agent was formulated Systems with and without Eastman CAB were prepared 1.0% by weight of Eastman CAB was used Eastman CAB high speed dispersed into the resin with the matting agent and titanium dioxide pigment Cured at 250 C for one and a half minutes - Peak metal temperature 232 C for 10 seconds Four different dry film thicknesses: 18-22, 22-28, 27-30, microns Five gloss measurements were taken of each panel at 20, 60 and 85

26 Improved gloss consistency Coatings with Eastman CAB show less variation in gloss readings

27 Improved gloss consistency Eastman CAB improves gloss consistency in semi-gloss formulations Tighter gloss specifications observed across the range of film thicknesses of 18 to 40 microns at 20, 60 and 85 Statistically significant

28 Improved gloss consistency Expected benefits to coil coaters Allows the coil coater to produce a tighter gloss specification with less variation Reduced "off spec" material Less recoating, leading to more efficient and economical processing

29 Improved pigment dispersion with Eastman CAB

30 Testing improved pigment dispersion To demonstrate the improved pigment dispersion with Eastman CAB a white polyester/melamine coil coating was formulated CAB added during the pigment dispersion (grind) stage Systems with and without Eastman CAB were prepared 1.0% by weight of Eastman CAB was used Evaluated titanium dioxide to date Cured at 250 C for one and a half minutes - peak metal temperature of 232 C for 10 seconds Spectrophotometer delta L measured: difference in lightness between standard and system with CAB Spectrophotometer delta B measured: difference in yellowness between standard and system with CAB

31 Improved pigment dispersion Use of Eastman CAB shows positive influence on visual whiteness

32 Improved pigment dispersion Eastman CAB improves the dispersion of titanium dioxide pigment in white coil coatings Eastman CAB is beneficial at increasing the lightness value - a higher lightness value produces an increase in whiteness Eastman CAB is beneficial at decreasing the Delta B which will results in a less yellow, bluer white Eastman CAB produces a brighter, whiter coil coating

33 Improved pigment dispersion Expected benefits to coil coater Allows the coil coater to produce a whiter, less yellow coil coating May provide greater hiding power, therefore less coating or titanium dioxide may be required to hide primer substrate specific data is being generated Possibility of using as a co-dispersant with colored pigments to further aid pigment dispersion specific data is being generated

34 Summary of benefits Improved metallic and pearlescent flake alignment Enhanced flow and leveling Improved gloss control with matting agents Higher gloss in high gloss systems Pigment dispersion improvement Eastman CAB reduces the complexity of the formulation by its multi-functional properties

35 Which CAB grade to choose? Product Use Level (% by wt) Eastman CAB Eastman CAB Eastman CAB Eastman CAB Metallic, pearlescent flake alignment Matting efficiency Eastman CAB Flow and leveling Eastman CAB Eastman CAB Eastman CAB Pigment dispersion and co-dispersants Eastman CAB Increased gloss Eastman CAB Eastman CAB Eastman CAB Higher hydroxyl functionality can improve adhesion, reactivity High molecular weight. Over-thinned batches can be brought back into specification

36 Improved appearance with Eastman CAB in PVDF* formulations * PVDF: Polyvinylidene fluoride

37 Testing appearance of PVDF* coil coatings A PVDF metallic formulation was prepared Formulations with and without Eastman CAB were prepared 1.0% by weight of Eastman CAB was used Initial laboratory application method on aluminum Q-panels (this is a low shear method) A slightly higher flop index of the experimental sample indicates the addition of Eastman CAB has improved the metallic flake alignment of the coil coating * PVDF: Polyvinylidene fluoride

38 Flop index values at low shear Experimental formulation with CAB indicates better appearance with a higher flop index

39 Testing appearance of PVDF coil coatings Initial laboratory application method on aluminum Q-panels (this is a low shear method) Same formulations with and without Eastman CAB were also applied using a pilot machine which simulates the application under high shear in an actual coil coating plant.

40 High-shear application Application and curing method, both samples thinned to the same application viscosity Method Running speed Dry film thickness (µ) Peak metal temperature 2 Roll 8m/Min 18-20µ 252 C for 10 seconds minimum 3 Roll 8m/Min 18-20µ 252 C for 10 seconds minimum

41 Flop index values at high shear STD: standard EXP: experimental (incl. Eastman CAB) Eastman CAB formulations have higher flop index and improved metallic flake orientation.

42 Improved appearance PVDF coil coating Without CAB 2 Roll (high shear) Flop Index 11.8 With Eastman CAB Roll (high shear) Flop Index 14.4

43 Metallic PVDF coil coating 3D projection through laser scanning confocal microscopy Without CAB applied under high shear (2 roll mill) Without CAB, formulation exhibits undesirable roughness and flop index Average RMS Roughness: 1.79 µ Flop index: 11.8

44 Metallic PVDF coil coating 3D projection through laser scanning confocal microscopy With Eastman CAB applied under high shear (2 roll mill) With CAB, formulation shows improved roughness and flop index Average RMS Roughness: 1.16µ Flop index: 14.4

45 Gloss values STD: standard EXP: experimental (with Eastman CAB) With CAB, coatings achieve an overall higher gloss value, positively impacting appearance

46 High shear rheology tests With CAB, the overall lower viscosity positively impacts metal flake distribution and appearance

47 Improved metallic flake alignment It is important to evaluate the coating under the actual high shear conditions of a production line to observe the benefit in metallic flake alignment that CAB provides. Under high shear rate the Eastman cellulose esters orientates metallic flakes such that they are flatter and more evenly distributed Improving the flake orientation produces a brighter appearance with lower surface roughness and higher "flop index" The formulations without cellulose esters are darker and produce a "grainy" appearance with higher surface roughness and lower "flop index"

48 Improved appearance, metal flake alignment Expected benefits to coil coater Improved metallic flake alignment and consistency from batch to batch Reduced "off spec" material Less customer complaints Less recoating, leading to more efficient and economical processing Brighter metallic and pearlescent coatings are more attractive to their customers

49 Conclusion

50 Technical Information The Technical Tip relating to this presentation (CE-COAT- 002) can be found on Eastman.com

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