12 Measurements of Formaldehyde Release from Building Materials in a Ventilated Test Chamber Hans N. O. Gustafsson
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National Testing Institute, Box 857, S-501 15, Boras, Sweden
Formaldehyde as a pollutant in the indoor air is usually connected with the use of formaldehyde based resins in e.g. building materials and in furniture. This article presents measurements of the formaldehyde emission from various products containing urea-formaldehyde (UF) or phenol-formaldehyde (PF) resins. The emission from all test objects have been measured in a ventilated test chamber at the standardized testing atmosphere 23 °C, 50 % RH according to the International Organization for Standardization (ISO). The emission from woodbased panels and other materials have been measured at a loading factor of 1.0 m/m and at an air change rate of 1.0 h . The values of the test variables are in agreement within the work of the European Organization for Standardization (CEN). Woodbased panels have also been tested with the perforator method. This method is European Norm according to CEN and gives an estimate of the extractable content of formaldehyde for especially particle boards. Formaldehyde release has also been investigated for different kind of pieces of furniture exposed in area to volume proportions in which they can be found in a small room. 2
3
- 1
In Denmark, Finland, Norway, Sweden and in West Germany the content of formaldehyde in woodbased panels are regulated by perforator values. In Denmark and West Germany these rules furthermore are based upon requirements of the formaldehyde emission to the air in ventilated test chambers. The regulations in Sweden include at the moment only UF-bonded particle boards. The boards should not exceed a perforatorvalue of 40 mg "free formaldehyde" per 100 gram dry board. 0097-6156/86/0316-0145$06.00/0 © 1986 A m e r i c a n C h e m i c a l Society
Meyer et al.; Formaldehyde Release from Wood Products ACS Symposium Series; American Chemical Society: Washington, DC, 1986.
146
F O R M A L D E H Y D E RELEASE F R O M WOOD PRODUCTS
I n t h e f u t u r e t h e Swedish formaldehyde r u l e s may i n c l u d e o t h e r UF-bonded p r o d u c t s as MDF-boards and t h e r e q u i r e m e n t s a l s o may be f o r m u l a t e d as e m i s s i o n r a t e s . On t h e b e h a l f o f t h e N a t i o n a l Board o f P h y s i c a l P l a n n i n g and B u i l d i n g , t h e Swedish N a t i o n a l T e s t i n g I n s t i t u t e has performed a s t u d y on the e m i s s i o n from p r o d u c t s bonded w i t h formaldehyde based r e s i n . The measurements have been performed i n a v e n t i l a t e d t e s t chamber a t s t a n d a r d i z e d c l i m a t e i n agreement w i t h i n t h e work o f t h e European O r g a n i z a t i o n f o r S t a n d a r d i z a t i o n , CEN. 16 West European c o u n t r i e s a r e r e p r e s e n t e d i n CEN.
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The
aim o f t h i s s t u d y was
t o compare
- t h e e m i s s i o n r a t e from d i f f e r e n t woodbased p a n e l s and o t h e r materials - the emission r a t e with the p e r f o r a t o r value - t h e c o n t r i b u t i o n o f formaldehyde from d i f f e r e n t p i e c e s o f f u r n i t u r e t o t h e t o t a l l e v e l o f formaldehyde i n a s m a l l room. The s t u d y does n o t i n c l u d e comparison o f d i f f e r e n t t y p e s o f diffussion barriers. Complete r e s u l t s w i t h a c l o s e r d e s c r i p t i o n o f the t e s t o b j e c t s and a r e v i e w o f o f f i c i a l t e s t i n g methods i n t h e N o r d i c c o u n t r i e s and West Germany a r e p r e s e n t e d i n a t e c h n i c a l r e p o r t from t h e Swedish N a t i o n a l T e s t i n g I n s t i t u t e (1) Materials The t e s t e d p r o d u c t s were bonded w i t h formaldehyde c o n t a i n i n g r e s i n and u s e d i n d o o r s . Most o f the woodbased p a n e l s and o t h e r m a t e r i a l s were m a n u f a c t u r e d d u r i n g 1984. The p a n e l s were n o t c o a t e d . I f n o t h i n g e l s e i s s t a t e d t h e t e s t o b j e c t s were m a n u f a c t u r e d w i t h U F - r e s i n and o f Swedish o r i g i n . As the most common UF-bonded m a t e r i a l t h e p a r t i c l e b o a r d s dominated t h e i n v e s t i g a t i o n . The s e l e c t e d b o a r d s i n c l u d e d b o t h o r d i n a r y UF-bonded (V-20) and m o i s t u r e r e s i s t a n t b o a r d s , (V-313) and were r e c e i v e d from e l e v e n f a c t o r i e s . The n i n e MDF-boards t h a t were t e s t e d were from f i v e d i f f e r e n t m a n u f a c t u r e r s i n Europe and have been c o m m e r c i a l l y a v a i l a b l e i n Sweden. One o f the b o a r d s was m o i s t u r e r e s i s t a n t and a n o t h e r flame r e s i s t a n t . Two o f the b o a r d s were t r e a t e d w i t h formaldehyde r e d u c i n g agents. Other woodbased p a n e l s as UF-bonded plywood, b l o c k b o a r d , PF-bonded plywood and h a r d b o a r d / f i b r e b u i l d i n g b o a r d have a l s o been t e s t e d . E m i s s i o n t e s t s have even been p e r f o r m e d f o r m a t e r i a l s such as UF-foam ( U F F I ) , m i n e r a l wool, p l a s t e r b o a r d and f u r n i t u r e f o i l . The UF-foam was m a n u f a c t u r e d by a l i c e n c e d c o n t r a c t o r i n 1979 and had n e v e r been i n s t a l l e d i n a b u i l d i n g . T e s t f u r n i t u r e , d e c o r a t i o n p a n e l s and l a m i n a t e d p a r g u e t f l o o r i n g were p u r c h a s e d d u r i n g 1984. Methods Emission. As t h e e m i s s i o n v a r i e s c o n s i d e r a b l y w i t h temperature and r e l a t i v e h u m i d i t y o f the a i r (1) i t i s n e c e s s a r y t h a t t h e t e s t i s p e r f o r m e d a t c o n s t a n t c l i m a t e . Our t e s t c o n d i t i o n s were i n agreement w i t h t h e t e n t a t i v e mehod o f CEN Q).
Meyer et al.; Formaldehyde Release from Wood Products ACS Symposium Series; American Chemical Society: Washington, DC, 1986.
GUSTAFSSON
12.
Formaldehyde
Release from
Building
Materials
147
The CEN method i s based upon the assumption t h a t the s i z e and shape o f the t e s t i n g chamber does n o t i n f l u e n c e the e m i s s i o n . D u r i n g the t e s t i n g the formaldehyde c o n c e n t r a t i o n i n the chamber w i l l r i s e and s t a b i l i z e a t a s t e a d y s t a t e c o n c e n t r a t i o n . A t c o n s t a n t c l i m a t e t h e s t e a d y - s t a t e c o n c e n t r a t i o n o r e m i s s i o n r a t e from the t e s t o b j e c t depends on the r e l a t i o n between the l o a d i n g f a c t o r and t h e a i r change r a t e . Good a i r c i r c u l a t i o n i n t h e chamber i s a l s o e s s e n t i a l (£). Formaldehyde e m i s s i o n was measured a t 23 *C and 50 % RH i n a v e n t i l a t e d t e s t chamber o f 1.0 m , t h e t e s t i n g c l i m a t e recommended by t h e I n t e r n a t i o n a l O r g a n i z a t i o n o f S t a n d a r d i z a t i o n (ISO) ( 5 ) . The exposed a r e a o f woodbased p a n e l s and o t h e r m a t e r i a l s were 1.0 m . Thus the l o a d i n g f a c t o r i n t h e chamber i s 1.0 m /m . The a i r change r a t e was 1.0 a i r c h a n g e p e r hour. S i n c e the e m i s s i o n from the edges o f the b o a r d o f t e n a r e h i g h e r , the edges a r e c o n s e q u e n t l y s e a l e d w i t h s e l f - a d h e s i v e aluminium t a p e . F o r p r e c o n d i t i o n e d t e s t p i e c e s the s t e a d y s t a t e c o n c e n t r a t i o n w i l l be r e a c h e d w i t h i n a week. 3
2
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2
3
P i e c e s o f f u r n i t u r e have been t e s t e d i n p r o p o r t i o n s i n w h i c h t h e y may be found e.g. i n a s m a l l l i v i n g room. The room i s assumed t o have a f l o o r a r e a o f 7 m w i t h a h e i g h t o f 2,4 m. The a i r volume i n t h i s room i s 17 m . The l o a d i n g f a c t o r f o r the t e s t e d f l o o r s i s thus 7/17 = 0.4 m /m . D e c o r a t i v e p a n e l s have been t e s t e d a t a l o a d i n g f a c t o r o f 1,0 m /m . Each o f the t e s t chambers has an i n t e r n a l volume o f 1.0 m and c o n s i s t s o f s t a i n l e s s s t e e l , w i t h the d i m e n s i o n 1 000 x 1 500 x 66 7 mm. The chambers a r e s u p p l i e d w i t h a i r o f c o n s t a n t temp e r a t u r e (23 ± 0,5°C) and c o n s t a n t r e l a t i v e h u m i d i t y (50 ± 3 % RH) from a c o n d i t i o n i n g p l a n t . The background c o n c e n t r a t i o n o f f o r m a l d e h y d e i n t h e s u p p l i e d a i r i s r e g u l a r l y measured and i s l e s s t h a n 0,02 ppm. The a i r exchange r a t e from the chambers i s p e r f o r m e d w i t h i n ± 3 % by exhaust pumps. The e x t r a c t a i r from the chambers i s n o t r e c i r c u l a t e d . The l e a k a g e o f a i r i n t o t h e chambers have been measured t o be l e s s t h a n 1 % a t an a i r change r a t e o f 5 p e r h o u r . The c o n c e n t r a t i o n o f formaldehyde i n the chamber a i r i s determined s p e c t r o p h o t o m e t r i c a l l y a f t e r sampling i n b o t t l e s . C h r o m o t r o p i c a c i d (&) o r a c e t y l - a c e t o n e (T) were u s e d as reagents* A c e t y l a c e t o n e r e a c t s more s p e c i f i c w i t h formaldehyde but the r e a c t i o n r e q u i r e s a h i g h e r temperature to be q u a n t i t i v e . 2
3
2
3
2
3
3
E x t r a c t i o n with toluene. The e x t r a c t a b l e c o n t e n t o f f r e e formaldehyde i n woodbased p a n e l s have been e s t i m a t e d w i t h the p e r f o r a t o r method. T h i s method i s an European Norm (8). W i t h t h i s method the t e s t p i e c e s (25 x 25 mm) a r e b o i l e d i n t o u l e n e i n 2 h . The t o u l e n e i s condensed c o n t i n o u s l y and b r o u g h t i n c o n t a c t w i t h water, which i s t i t r a t e d i o d o m e t r i c a l l y . T h e p e r f o r a t o r a p p a r a t u s i s made up o f s e v e r a l d i f f e r e n t g l a s s p a r t s . Results A l l data presented i n t h i s paper c o n s t i t u t e s s t e a d y - s t a t e values t h a t a r e t h e average o f a t l e a s t 3 measurements. The r e l a t i v e s t a n d a r d d e v i a t i o n o f t h e p r e s e n t e d s t e a d y - s t a t e v a l u e s i s about 5 % .
American Chemical Society Library 1155 16th St.,
N.w.
Meyer et al.; Formaldehyde Release from Wood Products Washington. 20036 ACS Symposium Series; American ChemicalD.C. Society: Washington, DC, 1986.
F O R M A L D E H Y D E R E L E A S E F R O M WOOD PRODUCTS
Supplyair
JL filter
Test chamber
Flow regulator
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1 m3 Flow meter
Exhaust f a n
Air conditioning plant
F i g u r e 1. The a i r c o n d i t i o n i n g p l a n t s u p p l i e s each chamber w i t h a i r o f c o n s t a n t temperature and c o n s t a n t r e l a t i v e humidity. ppm formaldehyde 1.0-
0.5
1 2
3
4 days
F i g u r e 2. D u r i n g t h e t e s t i n g t h e c o n c e n t r a t i o n o f formaldehyde i n t h e chamber w i l l r i s e and s t a b i l i z e at a steady s t a t e l e v e l .
Meyer et al.; Formaldehyde Release from Wood Products ACS Symposium Series; American Chemical Society: Washington, DC, 1986.
12.
GUSTAFSSON
Formaldehyde
Release from
Building
149
Materials
Woodbased p a n e l s and o t h e r m a t e r i a l s . A t an a i r change r a t e o f 1,0 p e r h o u r t h e g i v e n s t e a d y - s t a t e c o n c e n t r a t i o n c o r r e s p o n d s t o an e m i s s i o n r a t e w i t h an e q u a l number o f ppm formaldehyde/m x h . The e m i s s i o n from t h e t e s t e d p a r t i c l e b o a r d s and MDF-boards a r e g i v e n i n f i g u r e 3 and f i g u r e 4 r e s p e c t i v e l y . The e m i s s i o n from boards except p a r t i c l e boards a r e presented i n t a b l e I . 2
Table I
Steady-state concentration ppm f o r m a l d e h y d e 23°C, 50 % RH a i r change r a t e 1,0 t r 1.0 ml/ml
Perforator value mg formaldehyde/ 100 g d r y b o a r d
Blockboard
0,08
13
MDF-boards
1,8 0,9 2,0 1,7
63 50 71 70
3,2
125
1,7 0,20
86 27
0,31 0,13
23 10
Treatment/ Origin
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1
moisture resistant flame r e sistant posttreated w i t h NH 3
posttreated with (NH ) C0 4
3
Plywood
0,02 0,22 0,67
4 34 27
PF-bonded A-70 Far East
Hardboard/ Fiber building board
0,02
3
PF-bonded
P u r e wood Plasterboard UF-foam M i n e r a l wool Furniture f o i l
