# 3

Formaldehyd e Releas e fro m Woo d Pane l Product s Bonde d wit h Pheno l Formaldehyd e Adhesive s
J . A . Emer

y America nPlywoo d Association

, 701 1 Sout h 19t h Street , Tacoma , W A 9846 6 Bot h th e publishe

d literatur e an

d previousl

y unpublishe

d informatio

n obtaine

d b y th e structural pane

l industr

y indicat e tha tformaldehyd

e level s associate

d wit h pane l product s glue d wit h pheno l formaldehyd

e adhesive

s ar e extremel y low . Larg e dynami cchambe rtest s whic h simulate condition

s tha tmigh tb e foun d i n tightl y seale

d residence

s indicat

e consistently tha

tformaldehyd

e level s associate

d wit h freshly manufacture d phenoli

c pane l product

s ar e les s tha

n 0. 1 part

s pe rmillion . Th

e data, a s well a s theoretical considerations , also indi cat e tha tth e amoun to f formaldehyd

e contribute

d t o th e environmen

tb y phenoli

cpane l product

s shoul d rapidly approac h zer o a s th e smal l quantit

y o f formaldehyd

e ini tiall y presen

ti n th e product

s i s released . Virtuall y al l woo

d pane l product

s suc h a s plywoo d an d particleboard ar e manufacture

d usin g eithe rure

aformaldehyd

e o rpheno l formalde

hyd e adhesives . Ure

aformaldehyd

e adhesive

s ar e use d i n hardwoo

d plywoo d an d i n certai n type

s o f particleboards . Thes e adhesive

s ar e no twaterproof

, an d product

s mad e wit h the m ar e normall

y use d indoor s forpaneling , furniture , shelving an d floo runderlayment

. Pheno l formaldehyde

, o n th e th e othe rhand , i s use d t o mak e th e waterproo

f adhesive

s tha tar e use d i n structural woo

d pane l product

s suc h a s softwoo

d plywood

, oriented stran

d board, waferboar

d an d exterio r(phenolic

) particleboard . Thes e product

s ar e commonl

y use d forroof , floo ran

d wall sheathings , exterio rsidings , concret e form s an d i n pallet s an

d numerou

s othe rproducts . Althoug h formaldehyd

e emission

s fro m som e product

s glue d wit h ure aformaldehyd

e adhesive

s ca n caus e indoo rai rqualit

y problem

s unde rcertai n conditions , suc h problem

s hav e no tbee n associate

d wit h pheno l formaldehyde-bonde

d (phenolic

) products . Unfortunately, howeve rth e commonplac

e usag e o f th e generi cterm s "particleboard " an d "plywood

" ha s faile d t

o distinguis h betwee

n produc

ttype s an d ha s led t o agrea tdea l o f confusio

n amon g consumers

. Becaus e phenoli

cpanel s hav e no tpresente

d formaldehyde-relate d problem s i n th e marketplace

, ther e ha s no tbee n muc h nee d t o develo p informatio

n o n formaldehyd

e emission

s fro m thes e products . 0097-6156/86/0316-0026$06.00/ 0 ©198 6 America n Chemica lSociet y 

# This material may be protected by Copyright Law [Title 17 US Code]3

. EMER Y Wood PanelProducts Bonded with PhenolFormaldehydeAdhesives 2 7

Nevertheless , a considerabl e amoun t o f informatio nha s bee ngenerate d t o satisf y

curiosit y

an dt o answe r inquirie s concernin g emission s fro m phenoli c pane l products . Thi s informatio ni s summarize di nthi s pape r unde r thre e primar y subjec t headings : (1 ) Theoretica l Consid erations ; (2 ) Literatur e Review ; (3 ) Previousl y Unpublishe d Information . Theoretica l Consideration s
Th e chemica l an dphysica l characteristic s o f phenoli c resin s an d adhesive s mad e fro m the m sugges t tha t formaldehyd e emission s shoul d b e ver y

mino r (_1_

) . On e reaso nfo r predictin g lo w emission s i s tha t ver y littl e residua l fre e formaldehyd e i s presen t i nprepare dphe noli c resins . Thi s lo w fre e formaldehyd e conten t i s du e t o bot hth e us e o f lo w

formaldehyd e t o pheno l mol e ratio s i nresi npreparatio n an dt o th e tendenc y o f nearl y

al l th e formaldehyd e t o reac t irreversabl y

wit hth e phenol . Anothe r reaso nfo r predictin g lo w emission s i s tha t th e smal l amoun t o f residua l formaldehyd e tha t migh t b e presen t i nth e prepare d resi ni s diminishe deve nfarthe r b y reaction s whic hoccu r whe nth e resi ncures . Phenoli c resin s ar e cure dunde r hea t an dpressur e i na hot-press , usuall y unde r highl y

alkalin e conditions . Curin g tempera ture s ar e usuall y i nth e rang e o f 130-220°C . Unde r thes e conditions , unreacte dformaldehyd e continue s t o reac t wit hpheno l t o for m large r pheno l formaldehyd e polymers . Also , som e formaldehyd e react s wit h variou s chemica l constituent s i nth e wood . Moreover , som e formalde hyd e i s probabl y converte dt o methy l alcoho l an dformi c aci db y wa y o f th e Cannizzar o reactio n(J O . A thir dreaso nfo r predictin g ver y lo w emission s o f formaldehyd e fro m phenoli c panel s i s tha t th e cure dresi ni s extremel y stabl e an d doe s no t brea kdow nt o releas e additiona l formaldehyde , eve nunde r extremel y

hars henvironmenta l condition s (2) . Th e hig hresistanc e o f phenoli c resin s t o deterioratio nunde r sever e servic e condition s is , o f course , a principa l reaso nthe y ar e use ds o widel y i nmakin g ex terio r type s o f woo dpane l products . Becaus e o f thei r chemica l stabilit y

th e U.S . Environmenta l Protectio nAgenc y ha s declare dtha t pheno l formaldehyd e resin s represen t a "consumptiv e use " o f formalde hyde , meanin g tha t formaldehyd e i s irreversibl y consume di nit s reac - tio nwit hpheno l s o tha t th e formaldehyd e lose s it s chemica l identit y (3) . An y

formaldehyd e tha t migh t b e presen t initiall y i nfres h phenoli c panels , woul db e expecte dt o diminis hthroug htime , sinc e additiona l formaldehyd e i s no t release dfro m a breakdow no f th e res - i n . Thus , barrin g contaminatio nfro m othe r sources , formaldehyd e emission s associate dwit hthoroughl y age dphenoli c panel s shoul db e nil . Literatur e Revie w
Th e formaldehyd e emittin g potentia l o f woo dpane l product s ca nb e evaluate di nnumerou s ways , includin g th e us e o f dynami c chambe r test s (test s involvin g chamber s whic har e ventilate dan dsimulat e real-worl dconditions) ; stati c (unventilated ) tests , suc ha s2 8 FORMALDEHYD E RELEAS E FRO M WOO D PRODUCT S

desiccato r an d"equilibriu m jar " methods ; an dchemica l extractio n tests , suc ha s th e Europea nPerforato r Test . Thi s revie w wil l empha siz e th e result s fro m dynami c chambe r tests , especiall y th e "larg e scale " dynami c chambe r test , sinc e th e result s o f suc htest s ca n generall y

b e compare dan dsinc e th e result s ar e mor e representativ e o f real-worl dsituation s tha nar e th e result s o f othe r tests . Dat a fro m stati c test s an dchemica l extractio ntest s ar e mor e abstrac t tha nth e result s o f dynami c chambe r tests , an dsuc hdat a mus t there - for e b e correlate dwit hsom e typ e o f dynami c tes t i norde r t o b e use f u l i nterm s o f evaluatin g actua l potentia l exposures . Nestle r (4 ) thoroughl y reviewe dth e worldwid e literatur e o n formaldehyd e emission s fro m woo dproduct s publishe dthroug hJanuary , 1977 . Accordin g t o Blomquis t (1_ ) , Nestler 1 s literatur e revie w in - clude s onl y

thre e citation s whic heve nmentio nphenoli c adhesives , an dnon e o f thes e citation s mad e specifi c mentio no f an y problem s associate dwit hth e us e o f phenoli c panels . Sinc e Nestler 1 s revie w wa s published , som e additiona l informa tio no nformaldehyd e emission s fro m phenoli c panel s ha s appeare di n th e literature . Informatio nobtaine dusin g dynami c tes t chamber s i s summarize di nTabl e I . Perforato r an dtwo-hou r desiccato r dat a ar e summarize di nTabl e II . A s indicate di nTabl e I , dynami c chambe r tes t dat a hav e bee n obtaine di ninvestigation s usin g chamber s rangin g i nsiz e fro m 0.00 3 m 3 (0. 1 ft 3 ) t o 2 8 m 3 (100 0 ft 3 ) . Beside s thi s larg e chambe r siz e variation , th e studie s als o varie dwidel y wit hrespec t t o th e temperatures , relativ e humidities , loadin g rates , an dai r exchang e rate s use dfo r testing . Becaus e o f th e wid e variation s amon g th e studie s wit hrespec t t o thes e tes t parameters , i t i s no t possibl e t o mak e many

inference s fro m th e dat a presented . However , som e genera l trend s ar e evident , an dcertai nrelationship s develope dfro m studie s involvin g ure a formaldehyd e system s mak e i t possibl e t o mak e a fe w generalize dobservation s concernin g th e data . Althoug hTabl e I indicate s tha t formaldehyd e level s rangin g fro m 0.0 1 - 0. 3 part s pe r millio n(ppm ) hav e bee nobserve di nstudie s usin g dynami c tes t chambers , value s o f 0. 1 pp m o r lowe r wer e observe d i nmos t o f th e investigations . Thos e studie s i nwhic hth e highe r level s wer e foun d(i.e. , th e firs t two studie s summarize di nth e table ) use dver y smal l tes t chamber s (0.00 3 m 3 ) an drelativel y hig h temperatures , humidities , an dloadin g rates . Lowe r level s ar e shown f o r thos e studie s wherei nth e tes t parameter s approximate d"real - world " condition s (larg e tes t chamber s usin g temperatures , humidi ties , loadin g rates , an dventilatin g rate s approximatin g thos e foun d i nlivin gareas) . Th e highe r formaldehyd e level s associate dwit hth e firs t two studie s summarize di nTabl e I ca nprobabl y b e attribute dprimaril y t o th e relativel y hig htemperature s employed . Numerou s investiga - tion s hav e showntha t formaldehyd e level s increas e exponentiall y wit htemperatur e (_5-_7 ) . Severa l studie s hav e showntha t formaldehyd e level s associate dwit hwoo dpane l product s ca nincreas e b y mor e tha n a facto r o f 3 a s th e temperatur e increase s fro m 25° C t o 40° C (8)
. Th e exponentia l functio ndevelope db y Berge , et.al , (5 ) i s commonl y use dt o adjus t formaldehyd e dat a fo r temperatur e (9 ^ . I f thi s func tio nwer e applie dt o th e dat a o f Tabl e I i norde r t o adjus t al l form aldehyd e level s t o a commontemperatur e o f 25°C , th e correcte dlevel sTabl e I . Summary o f Publishe dDynami c Chambe r Tes t Dat a fo r Phenoli c Panel s
Dynami c Tes t Chambe r Parameter s Produc t Vol . Temp . R . H . Loadin g A i r Change s HCH O Level s Type^ 1 ) (M 3 ) <°F ) (% ) (m2/
m 3)?2 ) Per . Hr . (ppm)(3 ) REMARK S REFS .
P B .00 3 9 5 6 7 6. 7 1.7-6. 6 .05-.3< 4 ) Dat a represen t measurement s (10 ) o n4 sample s ove r 1 6 day s befor e an d afte r agin g fo r 9 0 day s @ 23°C , 44 % R.H. :

. 1 - . 3 pp

m unaged ; .0 5 - . 1
.12-.18< 4 ) pp

m aged . P B .00 3 77-10 4 7 5 19. 2 1.1 5 .12-.18< 4 ) Emission s measure dfo r two (8 ) board s a t two differen t .1(4 ) temperatures . SWP W .2 1 7 7 5 0 .1-1 0 1- 4 .1(4 ) Chambe r valu e estimate d (18,19 ) fro m stud y

o f emissio n rate s a t . 1 pp

m backgroun d leve l (rate^O) . W B 2 8 7 5 5 0 .4 3 . 5 .01-.04 Dat a represen t test s o n (20 ) 2 4 sample s fro m 8
.1,.06< « manufacturers . W B 2 8 7 5 5 0 .4 3 .5, 1 .1,.06< « Th e 2 formaldehyd e level s (12 ) correspon dt o th e 2
.1,.06<* > ventilatio nrate s shown SP P 2 8 7 5 5 0 .4 3 .5, 1 .1,.06<* > _i i

_ (12 ) P B 2 8 7 5 5 0 .4 3 .5, 1 .1,.06(* > _i i

_ (12 )
(1 ) P B = particleboar d ; SWP W = softwoo dplywood ; W B - waferboard ; SP P = souther npin e plywood . (2 ) Loadin g i s expresse di nterm s o f squar e meter s o f pane l surfac e are a pe r cubi c mete r o f chambe r volume . (3 ) Part s pe r millio n part s o f air , volum e basis . (4 ) Dat a valu e s take nfro m graphs .Tabl e II . Summary o f Publishe dTwo-Hou r Desiccato r an dPerforato r Tes t Dat a fo r Phenoli c Panel s

Produc t Type^ 1 ) Formaldehyd e Level s

P B

W B

W B

P P

SWP W 2-Hr . Desiccato r

Qg/ml)(2 ) Perforato r (mg/100g)( 3 ) Remark s Ref .

.11-.2 7 1.09-1.3 7

.1 6
.29-.8 5 Value s represen t 4

differen t particle - boa r a s .

Tw o hr . desiccato r value s represen t test s o n4 5 sample s fro m 1 1 manufacturers . Perforato r value s represen t 2 4 samp l e s fro m

8 manufacturers . 

## (10 )

O0 ) 

## (20 )

. 6
.1 8 (14 )
(18,19 )

(1 ) P B = particleboard ; W B = waferboard ; P P = phenoli c plywood ; SWP W = softwoo d plywood . (2 ) FT M

1-198 3 procedur e (16 ) wa s use di nal l studies . Value s represen t microgram s o f HCH 0 pe r m l distille dwater . I nthi s tes t 2 5 m l distille dwate r i na petr i dis hi s place di ndesiccato r wit heigh t 7 c m x12. 7 c

m specimen s fo r 2 hours ; an d th e wate r i s the nanalyze dfo r formaldehyde . (3 ) Tota l HCH 0 extractabl e wit hboilin g toluene , mg . formaldehyd e pe r 10 0 gram s dr y woo d(21) . o 70 

# >

X O m 70 m r m > m *ri to 0 

# 1 O 

## a

- o 70 O 

## a c n3

. EMER Y Wood PanelProducts Bonded with PhenolFormaldehydeAdhesives 3 1

woul dal l b e 0. 1 pp m o r lower . Suc ha nadjustmen t woul dmak e th e emissio ndat a fro m th e smal l chambe r test s simila r t o thos e fro m th e larg e chambe r test s summarize di nth e table . I t i s importan t t o not e her e tha t highe r temperature s probabl y increas e emission s fro m phenoli c panel s simpl y b y acceleratin g th e releas e o f tha t smal l amoun t o f residua l formaldehyd e tha t originate s fro m th e adhesiv e an dsubsequentl y become s adsorbe dt o th e woo dsub stanc e an dwate r i nth e wood . Becaus e phenoli c resin s ar e ver y stabl e chemically , an y temperature-relate dincreas e i nemission s woul dno t b e expecte dt o b e associate dwit hresi ndegradation . Consequently , temperatur e woul db e expecte dt o exer t muc hles s influenc e o nemission s fro m panel s whic hhav e bee naire dou t tha n fro m fres hpanels . Indeed , thi s tren di s shownb y th e data , a s dis - cusse dbelow . Th e informatio npresente di nTabl e I als o indicate s tha t th e loadin g an dventilatio nrate s fo r thos e two studie s i nwhic hth e highe r formaldehyd e level s wer e foun d(8,10 ) wer e highe r tha nfo r th e othe r studie s summarized . Th e influenc e o f thes e factor s o n formaldehyd e level s ha s no t bee nclearl y explained , however , sinc e th e amoun t o f dat a pertainin g t o phenoli c panel s i s s o limite dan d sinc e th e literatur e appear s t o b e contradictory . Studie s o f ure a formaldehyde-bonde dsystem s generall y indicat e tha t emission s increas e wit hhighe r loading s an ddecreas e wit hhighe r ventilatio n rate s (6,11) . Moreover , Meyer s (11 ) ha s showntha t ther e i s ofte n a goo drelationshi pbetwee nth e rati o o f ventilatio nan dloadin g rate s (N/ L ratios ) an dformaldehyd e concentratio ni ncontrolle dcham b e r experiments . Indeed , th e dat a presente di ntwo o f th e studie s summarize di nTabl e I (10,12 ) appea r t o b e i ngenera l agreemen t wit h thes e trends , sinc e th e dat a show decrease s i nformaldehyd e level s correspondin g t o increase dventilatio na t constan t loading . However , othe r studie s hav e indicate dtha t emissio nlevel s fro m ver y lo w emit tin g product s ar e no t influence dsignificantl y b y loadin g o r ventila - tio nrate s (6^) . Mor e researc ho nthes e relationship s i s needed . Th e effec t o f pane l ag e o nformaldehyd e releas e wa s investigate d i nth e firs t stud y summarize di nTabl e I , an dthi s variabl e wa s evi - dentl y ver y importan t wit hrespec t t o th e formaldehyd e level s measured . A s note di nth e Remark s colum ni nth e table , formaldehyd e level s range dfro m 0. 1 - 0. 3 pp

m fo r freshl y

manufacture dspecimens , whil e level s i nth e rang e o f onl y 0.0 5 - 0. 1 pp

m wer e associate dwit h matche dspecimen s tha t ha dbee naire dou t fo r 9 0 day s a t 23° C an d 44 % relativ e humidity . Thi s agin g effec t i s consisten t wit hth e theoretica l consideration s discusse dearlie r an dwit htes t result s t o b e presente dlate r i nthi s report . Th e two-hou r desiccato r an dPerforato r tes t result s showni n Tabl e I I ar e als o indicativ e o f ver y lo w formaldehyd e level s fo r phenoli c panels . A s wit hmos t o f th e result s obtaine di ndynami c chambe r tests , th e uniformit y o f thes e tes t results , bot hwithi nan d betwee nstudies , indicate s tha t th e variou s phenoli c pane l product s a r e quit e simila r wit hrespec t t o thei r emittin g potential . Twenty-fou r hou r desiccato r test s wer e als o conducte di nsom e o f th e studie s summarize di nTable s I an dI I (8,10) , bu t th e result s ar e no t shownsinc e differen t tes t procedure s wer e use di neac ho f th e studie s an dth e dat a are , therefore , no t comparable .3 2 FORMALDEHYD E RELEAS E FRO M WOO D PRODUCT S

I nadditio nt o th e studie s summarize di nTable s I an dII , Meye r (13 ) measure dformaldehyd e emission s fro m sample s o f phenoli c ply - wood , waferboar dan dparticleboar dusin g a modifie dversio no f th e Japanes e Industria l Standard , whic hi s a typ e o f 24-hou r desiccato r test . Emission s fro m woo dvenee r an da ure a formaldehyde-bonde d particleboar dwit hknownemissio ncharacteristic s wer e als o measured . Thi s researche r use dth e desiccato r tes t results , alon g wit hinforma tio nfro m

th e literature , t o estimat e th e maximu m amoun t o f formalde hyd e tha t migh t potentiall y b e contribute db y phenoli c pane l product s t o indoo r air . Assumin g a loadin g facto r o f 1.18-m^/m 3 an dri o ven tilation , calculation s showe dtha t phenoli c panel s woul dcontribut e les s tha n0.0 5 ppm . Assumin g a ventilatio nrat e o f one-hal f ai r chang e pe r hour , calculate dlevel s wer e belo w 0.002 5 ppm . Th e test s als o indicate dtha t formaldehyd e level s associate dwit hwoo dvenee r alon e (withou t an y adde dadhesive ) wer e abou t th e sam e a s level s as sociate dwit hphenoli c panels . N o backgroun dformaldehyd e level s wer e reported , however ; an dconsiderin g th e finding s o f studie s whic h a r e discusse dlater , backgroun dlevel s coul deasil y hav e bee na s hig h a s thos e reporte dfo r bot hth e venee r an dth e phenoli c products . Regardles s o f backgroun dleve l considerations , th e stud y generall y indicate s tha t phenoli c panel s emi t extremel y lo w level s o f formalde hyde , thu s corroboratin g th e finding s o f th e studie s discusse d earlier . Sundi n(14 ) als o measure dformaldehyd e emission s fro m a sampl e o f phenoli c plywoo di na stati c chambe r (n o ai r exchange ) wit ha volum e o f 1 5 m 3 . Th e temperatur e wa s maintaine da t 20° C an dth e loadin g rat e wa s 1 m^/m 3 . Relativ e humidit y wa s no t controlled , bu t wa s reporte dt o b e generall y i nth e rang e o f 30-50% . Th e exac t form aldehyd e leve l measure di nth e chambe r wa s no t reported , bu t th e autho r conclude dtha t .. . "th e emissio nfro m pheno l formaldehyd e (PF )

- glue dplywoo di s extremel y lo w an di npractic e i s negligibl e .. . " A grap hi s presente dtha t indicate s th e leve l wa s belo w 0. 2 ppm . A s indicate di nTabl e II , a Perforato r valu e o f 0. 6 mg/lOO g wa s als o reporte dfo r thi s plywood . Roffae l (15 ) measure dformaldehyd e emission s fro m a phenoli c particleboar dusin g th e "WKI-Method " whic hinvolve s suspendin g smal l sample s ove r 5 0 cm 3 o f distille dwate r i ntightl y close dpolyethylen e bottle s an dmeasurin g formaldehyd e level s i nth e wate r afte r varyin g times . Temperature s wer e maintaine da t 42°C . Thi s wor kindicate d tha t formaldehyd e releas e fro m th e phenoli c particleboard s cease d afte r a relativel y shor t reactio nperio d(approximatel y 9 6 hours) . Thi s findin g i s consisten t wit hth e resi nstabilit y consideration s discusse dpreviousl y unde r theoretica l considerations . Previousl y

Unpublishe dInformatio n

Muc ho f th e informatio npertainin g t o formaldehyd e emission s fro m phenoli c panel s ha s bee nobtaine db y manufacturer s o f thes e product s bu t ha s no t bee npublishe dpreviousl y i nth e ope nliterature . Thi s informatio nha s bee nobtaine dprimaril y t o for m

a basi s fo r answerin g consume r inquiries .

America nPlywoo dAssociatio nStudy . Probabl y th e mos t extensiv e stud y o f phenoli c pane l emission s wa s conducte db y W . F . Lehman no f Weyerhaeuse r Company fo r th e America nPlywoo dAssociation . I nthi s3

. EMER Y Wood PanelProducts Bonded with PhenolFormaldehydeAdhesives 3 3
investigation , formaldehyd e emission s fro m representativ e sample s o f a l l majo r type s o f phenoli c panel s wer e measure dusin g a Large-Scal e Dynami c Chambe r (LSDC ) an dtwo-hou r desiccato r tests . Pane l type s include dsouther npin e an dDouglas-fi r plywood , oriente dstran dboar dfro m two differen t manufacturers , waferboard , an da phenoli c particleboard . Fo r eac hproduc t type , fiv e 1.2 m x 2.4 m ( 4 f t x8 ft ) panel s wer e obtaine ddurin g a singl e shift . Th e panel s wer e kep t stacke dtogethe r durin g shippin g an dstorag e unti l thre e day s prio r t o teting , whe nthe y wer e place di nrack s i norde r t o allo w

ai r circulatio naroun deac hpanel . Strip s measurin g 15. 2 c m i nwidt hwer e cu t fro m th e center s o f fou r o f th e fiv e panels , paralle l t o th e shorte r pane l dimension . Fou r 2-hou r dessicato r tes t specimens , eac hmeasurin g 7 c m x12. 7 c

m (2-3/ 4 in . x5 in.) , wer e cu t fro m eac hstri pan dconditione dover night . Tw

o desiccato r test s wer e conducte dfo r eac hproduc t type , wit heac hdesiccato r containin g eigh t specimens . Test s wer e per forme di naccordanc e wit hstandar dprocedur e FT M 1 (16) . Specimen s fo r th e LSD C test s wer e prepare dfro m th e leftove r portion s o f th e fou r panel s whic hwer e cu t fo r desiccato r tes t speci - men s an dals o fro m th e fift hpane l sample dfo r eac hproduc t type . Mos t o f th e product s wer e teste drelativel y soo nafte r manufactur e an dagai nafte r the y wer e aire dou t fo r 3 o r mor e month s b y placin g the m

o nsticker s t o allo w ai r circulatio nbetwee nindi - vidua l panels . Th e tim e allowe dfo r airin g i s t o b e distinguishe d fro m pane l ag e o r ageing , sinc e formaldehyd e level s ten dt o remai n constan t fo r panel s whic har e stacke dtightl y together ; whereas , level s decreas e quit e rapidl y durin g airin g ou t (10 ) . Thus , airin g tim e i s mor e critica l tha nactua l pane l ag e whe nconsiderin g formal dehyd e emissions . Sinc e th e panel s fo r eac ho f th e product s studie d wer e kep t stacke dtogethe r unti l the y wer e conditione dfo r th e initia l testing , al l product s wer e relativel y "fresh" , i non e sense , regardles s o f th e tim e whic hha delapse dsinc e thei r manufacture . I nth e dynami c chambe r tests , th e larg e chambe r (55. 4 m 3 ) wa s loade da t a rat e o f 0.4 3 m^/m 3 , an dth e ventilatio nrat e wa s main taine da t 0. 5 ai r change s pe r hour . Th e tes t temperatur e wa s 2 5

_ + 1°C , an dth e relativ e humidit y wa s hel da t 5 0

_ + 5% . Ai r samplin g wa s accomplishe dwit hthre e set s o f doubl e impinger s a t on e lite r pe r minut e fo r 6 0 minutes , twic e pe r da y fo r two days . Formaldehyd e wa s analyze dusin g th e acetylaceton e procedur e (10) . Th e result s o f th e stud y ar e summarize di nTabl e II I whic h provide s 2-hou r desiccato r value s an ddynami c chambe r value s fo r bot hfres han daire dou t panels . Fo r mos t o f th e produc t types , bot hempt y

chambe r an dloade dchambe r formaldehyd e value s ar e pro vided , th e empt y chambe r value s representin g "background " measure ment s take njus t befor e th e chambe r wa s loaded . Thes e backgroun d level s represen t residua l formaldehyd e presen t i nth e chambe r fro m previou s testing . Th e dat a indicat e tha t th e loade dchambe r value s wer e belo w 0. 1 pp m fo r al l product s and , also , tha t th e backgroun dlevel s (i n th e empt y

chamber ) wer e o nth e sam e orde r o f magnitud e a s th e level s observe dwit hpanel s present . I nfact , th e dat a show tha t th e back groun dlevel s i nsom e case s wer e a s hig ha s th e level s measure dwhe n th e chambe r wa s full y loaded , especiall y afte r th e panel s ha dbee nTabl e III . Summary o f Formaldehyd e Tes t Dat a fo r Variou s Phenolic-Bonde dPane l Product s

2 Hou r Initia l Tes t Large-Scal e Dynami c Chambe r (3 ) Re-Tes t
Products^ 1 ) Desiccato r Jug/ml )(2 ) Pane l Ag e (Days ) W/Panel s

(ppm)(4 ) Empt y

(ppm)t4 ) Storag e

Tim e (Mo. ) W/Panel s (ppm)(4 ) Empt y

(ppm)t4 )

SPP , 1 3 mm

, 0.04(5 ) 4-pl y 0.0 8 3 2 0.04(5 ) 0.0 1 4 0.0 3 0.0 2 DFP , 1 4 mm

, 5-pl y 0.1 8 1 0.0 5 0.0 1 8 0.0 5 0.0 5 OS B No . 1 , 1 2 m m 0.1 4 1 9 0.0 7 0.0 1 

# — — — OS B No . 2 , (Sampl e 1) , 1 2 m m 0.0 2 2 1 0.0 7 0.0 7 3 0.0 4 0.0 2 OS B No . 2 , (Sampl e 2) , 1 2 m m 0.0 9 2 1 0.0 3 

# — — — — W B (Sampl e 1) , 1 2 m m 0.1 7 5 5 0.0 8 0.0 3 8 0.0 1 0.0 1 W B (Sampl e 2) , 1 2 m m 0.0 3 2 1 0.0 6 0.0 3 

# — — — PB , 1 9 mm

, hot-mel t coatin g 0.1 5 1 6 0.0 8 

# — 9 0.0 3 0.0 1 (1 ) SP P = souther npin e plywood ; DF P = Douglas-fi r plywood ; OS B = oriente dstran dboard ; W B = waferboard ; P B = particleboard . (2 ) Microgram s o f formaldehyd e pe r m l distille dwater . I nthi s test , 2 5 m l distille dwate r i na petr i dis hi s place di na desiccato r wit heigh t 7 c m x12. 7 c

m specimen s fo r 2 hours , an dth e wate r i s the n analyze dfo r formaldehyd e (16) . (3 ) Tes t conditions : 2 5 +

_1°C , 5 0 +

_5 % RH , 0. 5 ai r change s pe r hour , 0.4 3 m^/m 3 loadin g (pane l surfac e area/volume) . (4 ) Amoun t o f formaldehyde , part s pe r millio npart s o f ai r i nth e tes t chamber , volum e basis . (5 ) Th e sampl e wa s reteste da t 0 ai r change s pe r hour , an dformaldehyd e concentratio nwa s foun dt o b e 0.0 6 ppm . 3 70 

### > r O m x < O m To m r m > e n m t i 70 O

O o D 70 O 

## a c o H C/ 33

. EMER Y Wood PanelProducts Bonded with PhenolFormaldehydeAdhesives 3 5

aired . Becaus e o f th e comple xequilibri a involved , i t i s no t possibl e t o simpl y correc t th e pane l tes t dat a fo r backgroun dlevels . Therefore , i t i s no t feasibl e t o us e th e result s t o deriv e a nexac t emissio nvalu e fo r an y o f th e product s o r t o compar e th e variou s pan e l products . Instead , i t i s probabl y mos t pruden t t o simpl y conclud e fro m thi s stud y

tha t th e uppe r limi t o nemission s fro m al l type s o f phenoli c panels , a s determine di nth e larg e tes t chamber , i s les s tha n0. 1 ppm . Althoug hth e hig hlevel s o f "noise " du e t o backgroun dformalde hyd e level s preclud e meaningfu l statistica l comparison s betwee n emission s fo r variou s produc t types , certai nothe r comparison s ca n b e made . Fo r example , a statistica l t-tes t involvin g appropriatel y paire dobservation s indicate s a significan t differenc e a t th e 1% confidenc e leve l betwee nloade dan dempt y chambe r value s fo r th e fres hpanels . Thi s differenc e indicate s tha t th e panel s wer e prob abl y contributin g som e formaldehyd e t o th e tes t chamber , althoug hi t i s no t possibl e t o determin e ho w much , du e t o th e comple xequilibri a involved . A

simila r analysi s o f th e differenc e betwee nloade dan d empt y chambe r value s fo r aire dpanels , however , show s a barel y sig - nifican t t-valu e a t th e 5percen t confidenc e level . Thus , th e aire d panel s wer e probabl y contributin g ver y little , i f any , formaldehyd e t oth e ambien t atmospher e i nth e chamber . Evidently , th e smal l amoun t o f formaldehyd e presen t initiall y i nphenoli c panel s dissi - pate s a s th e panel s ai r out , s o tha t loade dchambe r level s approac h backgroun dlevels . I f backgroun dlevel s ar e ignored , a t-tes t involvin g paire d observation s representin g thos e 5set s o f panel s tha t wer e teste d bot hbefor e an dafte r th e panel s wer e aire dindicate s tha t fres h panel s emi t mor e formaldehyd e tha naire dpanel s (5 % confidenc e level) . Althoug hsuc ha statistica l compariso ni s tenuou s becaus e o f th e confoundin g effect s o f th e backgroun dlevels , i t i s supporte d b y th e conclusion s draw nabov e — i.e. , tha t fres hpanel s wer e appa rentl y increasin g th e level s o f formaldehyd e i nth e chambe r t o a sig - nifican t degree , whil e aire dpanel s wer e contributin g ver y little , i f any , formaldehyd e t o th e chamber . Th e two-hou r desiccato r value s showni nTabl e II I ar e simila r t o thos e associate dwit hth e studie s cite dearlie r i nthi s report , an d the y ar e als o indicativ e o f extremel y lo w formaldehyd e emission s fro m th e panels . Othe r Unpublishe dData . Tabl e I V summarize s additiona l emissio n dat a whic hhav e bee nsupplie dt o th e America nPlywoo dAssociatio nb y variou s phenoli c pane l manufacturers . Dat a fro m bot hlarge-scal e dynami c chambe r test s an d2-hou r desiccato r test s ar e provided . Thi s informatio nagree s wit htha t provide di nth e stud y describe dabov e an dagai ndemonstrate s tha t formaldehyd e emission s fro m phenoli c panel s ar e extremel y low . I nfact , fo r mos t o f th e products , th e chambe r backgroun dlevel s wer e a s hig ha s th e level s durin g testing , suggestin g tha t th e product s probabl y wer e no t eve ncontributin g an y formaldehyd e t o th e chambe r environment . Thes e dat a agai ndemon strat e tha t phenoli c panel s ar e suc hwea k emitter s tha t backgroun d formaldehyd e level s ca neasil y interfer e wit htesting .Tabl e IV . Result s o f Large-Scal e Dynami c Chambe r Test s an dTwo-Hou r Desiccato r Test s o nVariou s Type s o f Phenoli c Pane l Products ( D

Company Cod e Produc t

Type< 2 ) Pane l Ag e

a t Tes t (Days ) Dynami c Chambe r Tes t Parameter s

Preconditio n Time^ 3 ) (Days ) Loadin ;

Rate< 4 (m^/m 3 ) 

## f Temp . (C ) Rel .

Humid . (% ) Formaldehyd e Level s

Dynami c Chambe r Empt y (ppm ) Loade d

(ppm ) Two-Hr .

Desiccato r G*g/ml)(5 )

A SPP , 18mm , 4-pl y A SPP , 16mm , 5-pl y A SPP , 16mm , 5-pl y A DFP , 13m

m B PB , 16m

m C SPP , 16mm , 5-pl y C COMPLY , 16m m C WB , 16m

m C WB , 16m

m D PB , 19m

m D PB , 19m

m D PB , 19m

m E SPP , 12m

m 3 0

3 0 2 2 8

8

2- 3 2- 3 2- 3 2- 3 2-3(8 )

7 ( 9 ) 7(10 ) 2 0.9 5

0.9 5 0.9 5 0.9 5 0.4 9 0.4 9 0.4 3 0.5 2 0.5 2 0.4 3 0.4 3 0.4 3 0.4 3 2 3

2 3 2 3 2 3 2 4 2 4 2 4 2 4 2 4 2 4 2 4 2 4 2 5 0. 5 0. 5 0. 5 0. 5 1 1 1 1 1 1 1 1 1 4 8 4 8 4 8 4 8 5 0 5 0 5 0 5 0 5 0 4 5 4 2 4 2 4 2 1 1 1 1 1 5 5 5 5 5 5 4 8 5 0 5 6 0.01 5 0.01 0 0.005( 6 > 0.01 3
0.03-0.04(7 ) 0.03-0.04( 7 ) 0.03-0.04^7 ) 0.03-0.04^7 ) 0.0 1 0.0 1 0.0 1 0.02 2

0.02 0 0.01l( 6 > 0.01 7 0.0 4 0.0 3 0.0 4 0.0 3 0.0 5 0.0 4 0.0 5 0.0 4 0.04< 1 2 ) 0.5 1

0.0 9 0.1 3 0.1 7 0.1 8 0.2 2 0.1 7 0.2 0 0.34(H )
(1 ) Ventilatio nrat e wa s 0. 5 ai r change s pe r hou r fo r al l tests . Chromotropi c aci dwa s use d f o r HCHO analyses , unles s note dotherwise . Differen t tes t chamber s wer e use db y eac ho f th e companie s represented . (2 ) SP P = souther npin e plywood ; DF P = Douglas-fi r plywood ; P B = particleboard ; W B = waferboard . (3 ) Specimen s wer e preconditione da t th e sam e temperatur e an drelativ e humidit y a s i s give nfo r th e tes t chamber . (4 ) Loadin g i s give ni nterm s o f squar e meter s o f pane l surfac e pe r cubi c mete r o f ai r volum e i nth e chamber . (5 ) Al l desiccato r test s wer e performe di naccordanc e wit hth e procedure s give nb y Tes t Metho d FT M 1-198 3 (16 ) wit hedge s unseale dunles s note dotherwise . Value s represen t microgram s formaldehyd e pe r m l distille dwater . I nthi s tes t 2 5 m l distille dwate r i na petr i dis hi s place di na desiccato r wit heigh t 7 c

m x12. 7 c

m specimen s fo r 2 hours , an dth e wate r i s the nanalyze dfo r formaldehyde . s 70
> r 

## a m X 

## < D m 73 m r tn 

### > m T l 70 0 

# 1
O 

## a

- 0 70 

## o O 

## c n

— i (Z 3Tabl e IV . (continued )
m m
< (6 ) Pararosanilin e wa s use dfo r formaldehyd e analysis , rathe r tha nchromotropi c acid , usin g th e same pane l specimen s a s thos e use di nth e tes t whos e result s ar e reporte ddirectl y above . (7 ) Rang e typicall y encountere da t thi s tes t facility . ^ (8 ) Backgroun dformaldehyd e leve l i nconditionin g are a wa s 0.0 8 ppm . ^ (9 ) Backgroun dformaldehyd e leve l i nconditionin g are a wa s 0.0 3 ppm . ^ (10 ) Backgroun dformaldehyd e leve l i nconditionin g are a wa s 0.0 5 ppm . § (11 ) Averag e o f fou r test s involvin g sample s fro m two separat e panels : fo r eac hpanel , sample s fo r on e tes t ha dseale dedges , whil e thos e fo r th e othe r test s wer e unsealed . Rang e = 0.2 9 - 0.43 . ^ (12 ) Averag e o f fou r measurement s mad e o nfou r consecutiv e days . Rang e wa s 0.0 2 - 0.05 . j^ . 

# I

§ 

# ? I

8

- 

# i

-- J

## 3

8 FORMALDEHYD E RELEAS

E FRO M WOO DPRODUCT

S 

## Summar y an d Conclusion

s Al lth e availabl e

informatio

n indicate

s tha t formaldehyd

e levels associate

d wit h woo d pane lproduct

s bonde d wit h pheno lformaldehyd

e adhesive s ar e extremel

y low

. Dat a resultin

g fro m laborator

y studie s involvin g large-scal e

dynami c tes t chamber s consistentl

y indicat e tha t level s ar e belo w 0. 1 pp m unde r condition

s simulatin

g thos e whic h migh t b e foun d i n tightly seale d home s containin

g freshly

manufacture

d panels

. In fact , tes t chambe r level s ar e generall

y abou t th e sam e a s th e annua laverag e formaldehyd

e concentration

s whic h hav e bee n reporte d fo r outdoo r ai r i n man y citie s (17)

. More

over , th e data , a s wella s theoretica

lconsiderations

, indicat

e tha t th e amoun t o f formaldehyd

e contribute

d t o th e environmen

t b y phenoli c pane lproduct

s shoul d rapidl y approac h zer o a s th e smal lamoun t o f formaldehyd

e initiall y

presen t i n th e panel s i s released

. Literatur

e Cite d 1

. Blomquist

, R

. F

. "Formaldehyd

e Emission

s Ar e N o Proble m Wit h Woo d Product s Bonde d Wit h Phenoli c Resins" ; America

n Plywoo d Association

: Tacoma , WA , 1981

. 2

. Troughton

, G

. E

. Woo

d Scienc e 1969 , 1 , 172-6

. 3

. "Formaldehyde

; Determinatio

n o f Significan

t Risk ; Advanc e Notic e o f Propose d Rulemakin

g an d Notice, " Fed

. Register

, 1984 , 49 , 21820-98

. 4

. Nestler

, F

. H

. Max

. "Th e Formaldehyd

e Proble m i n Wood-Base

d Product s -- A n Annotate

d Bibliography" ; U

. S

. Dept

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: Fores t Product

s Laboratory

, Repor t FPL-8 , 1977

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. Berg

, A. ; Mellegard

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, P. ; Ormstad

, E

. B

. Hol z al s Roh-un d Werkstof

f 1980 , 38 , 251-5

. 6

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, B

. "Formaldehyd

e Stud y - - Testing o

f Plywoo d Panels" ; Weyerhaeuse

r Company

: Tacoma , WA , Repor t 0452-10 2 IN , 1981

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, G

. E

. For

. Prod

. J

. 1985 , 35 , 20-31

. 8

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, G

. E. ; Nagaoka

, M

. Woo d Scienc e 1981 , 13 , 140-50

. 9

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Tes t Metho d Fo r Determinin

g Formaldehyd

e Emission

s Fro m Woo d Product s -- Larg e Chambe r Method , FT M 2-1983" ; Nationa lParticleboar

d Association

: Gaithersburg

, MD , 1983

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, G

. E

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. J

. 1983 , 33 , 27-37

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. "Formaldehyd

e Emissio n Comparison" ; Champio n Internationa

l Corp. : Stamford

, Conn. , 1983

. 13

. Meyer

, B

. "Formaldehyd

e Releas e Fro m Phenoli c Bonde d Woo d Panels" ; America

n Plywoo d Association

: Tacoma , WA , 1981

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. Sundin

, B

. Proc

. 12t h Wash

. Stat e Univ

. Internationa

lSympos

. o n Particleboard

, 1978 , p.251

. 15

. Roffae

lE

. Proc

. 12t h Wash

. Stat e Univ

. Internationa

lSympos

. o n Particleboard

, 1978 , p.233

. 16

. "Smal

lScale Tes t Metho d Fo r Determinin

g Formaldehyd

e Emission

s Fro m Woo d Product s -- Tw o Hou r Desiccato

r Test , FTM1-1983"; Nationa lParticleboar

d Association

: Gaithersburg

, MD , 1983

. 17

. "Indoo

r Pollutants, " Nationa lResearc h Council , Nationa

l Academ y Press : Washington

, D.C. , 1983

, p . 93

.

## 3

. EMER Y 

## Wood

PanelProducts

Bonded

with PhenolFormaldehyde Adhesives

3 9 18

. Matthews

, T

. G. ; Hawthorne

, A

. R. ; Daffron

, C

. R. ; Reed

, T

. J. ; Corey , M

. D

. Proc

. 17t h Wash

. Stat e Univ

. Internationa

l Particleboard/Composit e Materials

Sympos. , 1983

, p . 179

. 19

. Matthews

, T

. G. ; Hawthorne

, A

. R. ; Daffron

, C

. R. ; Reed

, T

. J

. Proc

. Ai r Pollutio

n Contro lAssoc

. Specialt

y Conf

. o n Meas

. an d Monitorin

g o f Noncriteri a

Toxi c Contaminants

, 1983 , p . 150

. 20

. "Formaldehyd

e Emissio n Surve y o f th e Waferboar

d Association" ; Nationa lParticleboar

d Association

: Gaithersburg

, MD , 1984

. 21

. Roffael , E. ; Mehlhorn , L

. Hol

z als Roh-un d Werkstof

f 1980 , 38 , 85-8

. RECEIVE

D

## Januar y 14 , 198 6