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Technical Service Request Report

Technical Service CE BL COATINGS

Customer: Ciba Originator: Author ref.: Date: Titan Wood BV, Netherlands C. Schaller Raphael Meyer 08.02.2006 Lab Report No: 12661

Performance evaluation of acetylated wood from Titan Wood Ltd.

Tested light stabilizers: Coating system: Substrate: Exposure: Tested properties: LIGNOSTAB® 1198; TINUVIN® 477DW; TINUVIN® 5100 WB acrylate Radiata pine; Scotch pine; Accoya Xe-WOM CAM 7, prEN927-6 CIE-L*C*h and E*; Gloss 60°, Cracking

1.

Introduction

Acetylated (Accoya) wood from Titan Wood Ltd. based in the UK, (www.titanwood.com) is a highly durable wood for high performance application like window frames etc. In this study the performance of TINUVIN® 477 DW as well as the LIGNOSTAB® 1198 concept should be evaluated on acetylated and non-modified radiate pine. Due to the use of UV absorber as well as Lignin stabilizer a better long term performance in terms of color retention as well as mechanical properties is expected.

2.

·

Target

Artificial exposure of acetylated and non-modified radiate pine

3.

Summary

As summary it can be stated that Accoya still needs to be protected by the use of a coating with sufficient UV-VIS light protection to avoid any damages due to radiation and water. Here the use of UVA, like TINUVIN® 477 DW and LIGNOSTAB® 1198 as lignin stabilizer can be recommended not only in terms of color retention but as well in terms of retaining mechanical properties.

4. 4.1.

Experimental Chemicals and Materials

All data and advice in this report is given in good faith but without acceptance of liability for the consequences of reliance thereon as conditions of use lie outside our control. Customers should always carry out their own tests to establish the suitability of any process or product for their intended application.

All wood panels (radiata pine, acetylated radiata pine (Accoya), scotch pine) have been

Unsere Beratung erfolgt nach dem heutigen Stand unserer Kenntnisse und ohne Gewähr. Eine Haftung können wir nicht akzeptieren, da die Anwendung ausserhalb unserer Kontrollmöglichkeiten liegt. Wir empfehlen die Durchführung eigener Tests, um die Eignung der Prozesse oder Produkte für die beabsichtigten Zwecke zu überprüfen.

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TSR 12661 supplied by company Titan Wood Ltd. The evaluated light stabilizer compositions are summarized in table 1. The aqueous acrylic formulation used in this study is shown in table 2. Tab. 1: Evaluated light stabilizer compositions in aqueous coatings 1 # Pre-treatment 2 Top coat 3 12661-x-y-1 12661-x-y-2 5 % TINUVIN® 477DW 12661-x-y-3 5 % TINUVIN® 477DW + 0.5 % TINUVIN® 5100 12661-x-y-4 1 % LIGNOSTAB® 1198 5 % TINUVIN® 477DW + 0.5 % TINUVIN® 5100

1) 2) 3) Internal serial x = 1: Xe-WOM CAM 7; x = 2: prEN927-6; x = 3: Pfeffingen, CH y = 1: radiata pine; y = 2: Accoya; y = 3: scotch pine % in deionised water % on total paint

Tab. 2: WB acrylic formulation used in this study Joncryl® 8383 EFKA® 2526 Deionised water Dowanol PnP GLASWAX® E1 RHEOVIS® PU10 EFKA® 3580

85.00 0.40 1.50 7.50 3.60 1.50 0.50 100.00

4.2.

Application and Methods

Radiata pine (modified, untreated); Scotch pine (untreated) Brush 1 x 80 - 100 g/m2 2 x 130 - 150 g/m2

· Application Substrate: Application: Impregnates: Lacquers:

· Color measurements Measured with Minolta CM-3600d (gloss included) and calculation of L*, a*, b*, C*, h and E* with CGREC software according DIN 6174 · Gloss readings Gloss evaluation at 60° with Byk/Gardner Micro-Tri-Gloss according DIN 67530 · Cracking evaluation Cracking evaluation is performed visually according DIN EN ISO 4628-4

·

Accelerated weathering Xe-WOM CAM 7 (DIN EN ISO 11341 A)

Machine type: Light source: Filter combination: Procedure: Atlas Weather-O-meter Ci-65 A (two-tier rack) 6.5kW Xenon burner water-cooled Outer filter Boro S / Inner filter Boro S A

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TSR 12661

Cycle conditions: 102 min 0.35 W/m² @ 340 nm (60±2) °C (50±5) % 18 min 0.35 W/m² @ 340 nm (35±2) °C (95±5) % Light Irradiance, controlled Black panel temperature Rel. humidity at the end of the dry period Light and Spray Irradiance, controlled Black panel temperature Rel. humidity

·

Fluorescent UV light exposure for wood (prEN927-6)

Machine type: Panels size: 24 h (45±3) °C 48 x 2.5 h 0.77 W/m² (60±3) °C 0.5 h (22±3) °C Total cycle time = 168 h Q-Lab QUV 300x75x10mm Condensation Black panel temperature UV light Irradiance Black panel temperature Dark and spray Black panel temperature =7 days

5. 5.1.

Results Color deviation

The color deviation of radiata and scotch pine after 500 h Xe-WOM CAM 7 and 336 h prEN9273/7

TSR 12661 6 exposure is shown in figure 1.The color deviation of radiata pine with and Accoya during XeWOM CAM 7 exposure is shown in figure 2. The coloristic data of radiata pine and Accoya after 500 h Xe-WOM CAM 7 exposure are shown in figure 3. The color deviation of Accoya after 500 h Xe-WOM CAM 7 and 336 h UV-A-340 is shown in figure 4.

25

25.00 24.81

Color deviation of Radiata and Scotch Pine after artificial exposure

Radiata Pine Scotch Pine

20

Color deviation E

15

14.37 13.24

14.68 12.81 12.05

11.45

10

7.66 5.03 7.22

8.19 5.99

5

3.36

0

(1-1-1)/(1-3-1) (1-1-2)/(1-3-2) (1-1-3)/(1-3-3) (1-1-4)/(1-3-4) (2-1-1)/(2-3-1) (2-1-2)/(2-3-2) (2-1-3)/(2-3-3) (2-1-4)/(2-3-4) UVA (1%) UVA/HALS UVA 336 h prEN927-6 (1%) UVA/HALS

500 h Xe-WOM CAM 7

Fig. 1

Color deviation of radiate and scotch pine after 500 h Xe-WOM CAM 7 and 336 h prEN927-6 exposure

30 Color Deviation of Radiata Pine and Accoya during Xe-WOM CAM 7 exposure (number in brackets reflects LIGNOSTAB® 1198 pre-treatment) 25

Color Deviation E

20

15

10

5

(1-1-1) Pine: (1-1-2) Pine: UVA (1-1-3) Pine: UVA/HALS (1-1-4) Pine: (1 %) UVA/HALS (1-2-1) Accoya: (1-2-2) Accoya: UVA (1-2-3) Accoya: UVA/HALS (1-2-4) Accoya: (1 %) UVA/HALS 0 500 1000 1500 2000 2500

0

Xe-WOM CAM 7 exposure / h

Fig. 2

Color deviation of radiata pine with and Accoya during Xe-WOM CAM 7 exposure

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TSR 12661

20 Coloristic after 500 h Xe-WOM CAM 7 exposure Coloration 10 Brightening

Color deviation

0 L* C* H* E* Discoloration

(1-1-3) Pine: (1-1-4) Pine: (1%) (1-2-1) Accoya: (1-2-3) Accoya: (1-2-4) Accoya: (1%)

-10 Darkening -20

(1-1-1) Pine: -

5% TINUVIN® 477 DW + 0.5% TINUVIN® 5100 Radiata Pine

5% TINUVIN® 477 DW + 0.5% TINUVIN® 5100 Accoya

Fig. 3

Coloristic data of radiate pine with and without acetylation after 500 h XeWOM CAM 7 exposure

25 Color deviation of Radiata Pine and Accoya after artificial/natural weathering 20

Color deviation E

16.57

15.01

15.70

13.90 12.47

16.18

14.52

15

1000 h Xe-WOM CAM 7 6 month natural 1008 h prEN927-6

7.92

10

6.57

6.75 5.42 5.23 5.50

5

0

(1-1-1)/(2-1-1)/(3-1-1) non-modified (1-2-1)/(2-2-1)/(3-2-1) (1-2-2)/(2-2-2)/(3-2-1) (1-2-3)/(2-2-3)/(3-2-1) (1-2-4)/(2-2-4)/(3-2-1) 1% LIGNOSTAB® 1198

5% TINUVIN® 477 DW 5% TINUVIN® 477 DW + 0.5% TINUVIN® 5100 Accoya

Fig. 4

Color deviation of acetylated radiate pine after Xe-WOM CAM 7 and prEN9276 exposure

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TSR 12661

5.2.

Pictures

The pictures of radiata pine and Accoya after 2000 h Xe-WOM CAM 7 are shown in figure 5.

Fig. 5

Pictures of radiata pine and Accoya after 2000 h Xe-WOM CAM 7 exposure

6.

Conclusions

Based on the results of the artificial weathering it could be stated that radiata pine and scotch pine behaves similar. A strong increase in E can be seen without additives. E can be significantly reduced by using UVA; here the use of HALS does not influence the color retention, i.e. HALS are protecting the paint film itself against surface defects like e.g. cracking. By far best performance is obtained by using the LIGNOSTAB® 1198 concept (s. fig. 1). The comparison of E in fig. 2 shows obvious different behavior of Accoya against non-modified pine. Here in general the use of UVA leads to a higher E compared to the non-stabilized pine. This increase in E is explained in fig. 3. Whereas for the non-modified pine the use of UVA and LIGNOSTAB® 1198 concept reduces the darkening and coloration, brightening and discoloration effects can be seen for the Accoya. These discoloration/brightening ("bleaching") effects are mainly induced by visible light what can be seen in figure 4. These effects appear only under Xenon exposure conditions and not under UV-A light exposure. An explanation for this brightening can be found in fig. 5 where it is shown clearly that acetylated pine shows obviously darker color compared to non-modified pine. So the bleaching effects are caused by minor visible light sensitivity of chromophores which has been built during the acetylation process. Nevertheless yellowing of the non-stabilized Accoya can be seen after Xenon exposure which can be explained by lignin degradation starting from carbonylic structures, i.e. hydroxylic structures are blocked via acetylation. (see Pathways of Lignin degradation, Phenacyl way) As summary it can be stated that Accoya still needs to be protected by the use of a coating with sufficient UV-VIS light protection to avoid any damages due to radiation and water. Here the use of UVA, like TINUVIN® 477 DW and LIGNOSTAB® 1198 as lignin stabilizer can be recommended not only in terms of color retention but as well in terms of retaining mechanical

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TSR 12661 properties. A more detailed schematic illustration about proposed color deviation mechanism is shown in the customer presentation given the 10.08.2006. The presentation, pictures and analytical data (CIE-Lab) during exposure can be found on the delivered CD

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