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## Document

Number: 

# 79 ) 11-1-8 0
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## A ^4-5 2 JC~T-$Q 

# Th e Wh y an d Ho w o f Reducin g Styren

e Emissions A lmos tal

l composit e molder s us e styrene-containin g resins . Whethe ryou're pultrudin g ladderrail , contac tmoldin g modulartub-and-showe runits , polyme r § castin g sinks , usin g RTM t o mol d hatc h covers , makin g continuou s panels , o rcompres sio n moldin g automotiv e hoods , you rproces s probabl y use s —an d emit s —styrene . Styren e plays tw o key roles i n aresin system . Befor e curin g takes place , i c reduces th e v f viscosity ofth e polyeste rresin s o thati tca n flow, we tth e reinforcement, an d b e applie d | t o di e mold . An d durin g curing , styren e react s to for m th e cross-links (chemica l bonds ) j betwee n th e polyeste rresin molecules . Thi s cross-linkin g reactio n transforms rhe resin J from aliqui d to asoli d material . /—-

_ I n thi s article , let s review th e variou s technologie s thatar e useful i n reducing.th e J
amoun to f

styrene thati s los tfrom composit e manufacturing pn 

### Wh yreduc e emissions ? Wh y shoul d yo u b e intereste d i n reducin g di e amounV-ofstyrenS/ihaNiribsc-fror n you rf

— — -JJ^QCK£ T

^ ~ | process ? On e obviou s answe ri s —no w don' tb e shy, we'r e al l capitalists here^smoney. A Styren e i s no tfree. Itdoesn' tbubbl e u p from awel l i n th e bac k o f you rpropert

y (bu tcall j| ; m e immediatel y i f

i tdoes!) . Yo

u pay fo rit . An d i f

i tevaporate

s an d flies awa y ou tyou rj fe window , that' s reall

y you rmone y floating awa y o n th e breez

e Anothe rimportan treason t o reduc e styren e losse s fro m you rproces s i s protectin g ' k th e healt

h o f you remployees . Unde rou rindustr y agreemen

twit h OSHA , composit e industr y employer

s ar e required to limi texposure o f worker s t o styren e t o 50pp m (time weighted-averag e over8 hours ; exposure s u p t o lOOpp m ar e permitte d fo rn o mor e than I

• 1 5 minutes) . Employer s ar e encourage d t o us e engineerin g control s (ventilation ) t o kee p exposure s belo w thes e limits , bu trespirator s ma y b e use d i n som e cases . Reducin g th e |

b yJoh n Schweitze r Composites

Fabricators

Association

1 2 Composites Fnbrictitio'iljune 199 8

### P. 3

un t o f styren e los t

fromyou r

proces s reduc e th e resource s neede dt o instal l operat e ventilatio n systems , o r th e un t o f tim e neede dt o manag e respi

r programs . Eve n if yo u are alread

y meetin g th e D mlimit , furthe r

reductio n i n styren e : s fro myou r

proces s ma

y improv e th e cin g conditions , morale , an dqualit y roduct s produce di n you r facility

. An dhere' s aheads-u p o n occupa a l exposures . Ver

y extensiv e epidemi

ical studie s o f

composit e industr y cer s di dno t

sho w an y relationshi p /ee n exposur e t o styren e an dchroni c t h problems

. However , recen t irc h wit h laborator y animal s ha s ;este dtha t styren e exposur e ma

y hav e rtor y effect s (tha t

is , effect s t o nasa

l e , perhap s affectin g th e ability t o c r odors)

. Th e industr y i s no w cin g t o determin e i f

thi s findin g ha s relevanc e t o humans

. I n an y case , th e amon g u s wil l loo k

t o th e da

y whe n istr y scientist s coul drecommen da n i lower occupationa l exposur e limit

. A thir dreaso n t o minimiz e th e los s o f :n e fro myou r

proces s i s t o reduc e th e ironmenta l footprint " o f you r facility , iicin g styren e losse s fromyou r proces s mea n tha t

les s styren e leave s you r t
. Th e scienc e o n styren e toxicolog y environmenta l fat

e clearly sho w tha t industr y i s no t

causin g an y significan t c h ris k o r environmenta l damage , i n amount s o f

styren e commonl y te db y industr y facilities

. However , cin g styren e losse s fromyou r proces s mea n fewe

r odo r complaint s from
• neighbors

. It

ma y als o mean that ar e more-readil y abl e t o mee t your ' s fence-lin e limi t

fo r styrene
. An d Iy , i n area s with smo g problems , :cin g you r

styren e emission s wil l c e th e contributio n o f

you r facilit y t o problem , sinc e styren e —lik e othe r 2 s —react s i n th e atmospher e t o hel p 1 smog . Th e final importan t

reaso n yo u il dreduc e styren e emission s is tha t it increas e you r

credibility amon g you r loyee s an dyou r

community

. A s lica l processors , composit e molder s inevitabl y fac e som e (probabl y arranted ) skepticis mabou t thei r mirmen r t o full y protec t worker s an d hbors

. A n aggressiv e progra mt o imiz e styren e emissions , whe n 

## •fFlo w applicator s an dpressure-fe droller s Controlle dspra

y Covere dwe

t area s —pultrusio n 

## 49 % 23 % 60 % properl y manage dan dcommunicated , wil l hel p buil dtrus t

betwee n yo u an d you r employee s an dcommunity

. 

### Ho wt o reduc e emission s Ther e are basically onl y tw o way s yo u ca n reduc e th e amoun t

o f styren e los t

fro m you r composit e moldin g process : us e les s styrene , o r

preven t exposure ofth e styren e t o air

. Emissio n reductio n technologie s include di n th e use-less-styren e grou p are low-styren e resin s an dfilledresi n systems
. Th e second , prevent-exposure-to-ai r grou p include s low-emitting resi n appli

catio n technologies , suppressants , controlle dspray , airflo w management , an dclosed-moldin g processes . 

### Low-styren e resin s On e wa y fo

r som e molder s t o minimiz e th e los s o f

styren e fromthei r

proces s i s t o us e resin s formulate dwit h les s styrene
. Resi n supplier s offe

r avariety o f

resin s wit h lowe r

styren e content , man y o f whic h wer e formulate dt o mee t th e requirement s fo

r California' s SCAQM D Rul e 116 2 an dsimila

r regulations

. Som e o f th e low-styren e resin s are mad e with specia

l shorter-chai n polyeste r molecule s tha t

permi t lowe r styren e conten t whil e stil l maintainin g workabl e viscosity an dothe r

properties

. Othe r low-styren e resin s emplo y viny l toluene , p-methy l styrene , or

othe r non-styren e monomers ; thes e othe r

monomer s hav e lowe r vapo r pressure s tha n styrene , s o les s o f th e materia l evaporate s whe n expose d t o air

. An dsom e low-styren e resin s are mad e with combination s o f short-chai n polyester s an dlow-volatility monomers . Whil e th e us e o f

low-styren e resi n sound s like i s shoul db e relativel y painless , thi s technolog y is no t fo r every one . First , fo

r man y moldin g processes , suc h a s pultrusion , compressio n molding , an deve n flow-coater

applicatio n o f

resi n t o a n ope n mold , reducin g th e styren e conten t of aresi n ma

y no t resul t i n signif

ican t reduction s i n emissions

. Further , reducin g th e styren e conten t of aresi n mean s tha t

it i s adifferen t

resin

. I t wil l likel y hav e differen t glas s wettin g ability , fille

r loadin g capacity , gel times , viscosity , an drheologica l properties

. Usin g low-styren e resi n may requir e tha t yo u emplo y different

formulas , applica

tio n technologies , an droll-ou t proce dures

. An dproduct s molde dusin g low

styren e resin s wil l hav e differen t chemica l an dphysical properties

. Styrene , afte r all , i s primaril y areactiv e monomer , no t a solvent

. Changin g th e amoun t o f styren e i n aresin , o r

changin g th e typ e o f monome r used , wil l chang e th e propertie s o f th e product , sometime s unacceptably

. In som e cases , it' s possibl e tha t th e us e o f alow-styren e resi n wil l actuall y increas e emissions , if

, fo r example , longe r roll-ou t i s neede dt o we t

th e glass , o r

i f mor e resi n i s neede dt o offset decrease d physica l properties

. Still , molder s —especiall y ope n molder s usin g traditiona l spray applica

tio n o f resi n o r ge l coat —shoul dwor k wit h low-styren e system s t o se e if th e us e o f thes e material s decrease s emission s whil e stil l allowin g acceptabl e processin g an dproduc t

performance

. Man y o f th e molder s require dro us e th e 1162-styl e low-styren e resin s wer

e abl e t o overcom e initia l processin g problems , an dtoda y us e thes e material s an denjo y th e benefit s o f lowe r styren e emissions

. 

### Filler s A secon dwa

y t o reduc e styren e emission s is t o us e les s resin

. Thi s migh t mea n engineerin g aproduc t

s o tha t it use s onl y a s muc h resin a

s neede dt o provid e th e require dproperties , bu t

mor e ofte n thi s approac h mean s addin g a n inert fille r t o th e formula

. Filler s reduc e th e amoun t o f resi n neede d(thereb y reducin g styren eP. 4

usag e an dconsequentl y emissions) , whil e possibl y increasin g produ astiffnes s o r fire resistanc e (dependin g o n th e typ e o f filler used)

. Typically , processin g an dproduc t performanc e requirement s wil l determin e wha t typ e an dho w muc h fille r ca n b e used

. Som e suppressants , an dsom e o f di e ne w non-spra y applicatio n technologies , ma y no t b e compatibl e wid i filledsystems
. 

### Low-emittin g resi n applicatio n technologies Whil e th e emissio n reductio n technolo

gie s discusse dabov e wor k b y decreasin g th e amoun t

o f styren e use dt o mak e a product , th e technologie s describe di n thi s an dth e followin g section s work b y reducin g di e contac t

o f styren e wit h air

. I f yo u wante dt o reduc e di e amoun t o f wate r evaporatin g fro mapuddle , wha t woul dyo u do ? Well , yo u coul dobviousl y mo p u p som e o f

di e water , s o ther e woul d b e les s t o evaporate
. Thi s woul db e analo

gou s t o rh e use-less-styren e technologie s describe dabove

. Bu t wha t i f yo u neede ddi e water

(like w e nee dstyren e t o provid e thos e cross links) ? Well , yo u coul dreduc e di e surfac e are ao f th e wate r

b y coverin g th e puddl e wit h aplasti c shee t

o r b y scoopin g th e wate r int o abucket

. Thi s i s analogou s t o th e minimize-exposure-to-ai r technologies

. Fo r example , th e variou s non atomize dapplicatio n technologie s lik e pressure-fe drollers an dflow-applicator s (als o calle dflo w coaters ) work t o reduc e emission s b y minimizin g di e contac t o f resi n t o air

. I n traditiona l spray applica

tio n o f resin , ver y smal l "atomized " droplet s ofresi n trave l fromth e spray gu n t o th e mol d—o r

t o th e floor , walls , o r filter s ofth e spra y booth ! —creatin g very hig h surfac e area s o f

we t resin , an dconse quentl y hig h emissions

. B y contrast , flow-applicators delive r

stream s ofresi n t o th e mold , rathe r

tha n atomize ddroplets ; th e applie dresi n ha s amuc h lower surfac e are aan dtherefor e lowe r emissions

. An d wit h pressure-fe drollers , ther e i s no t even astrea mo f

resin

. Anothe r low-emittin g resi n applica

tio n technolog y i s resi n impregnation , wher e glas s mat s ar e mechanicall y fed throug h aresi n bath , an dthe n applie dt o th e mold

. Again , there' s n o spra y (o r stream ) o f

resi n throug h th e air , an dmor e o f th e resi n i s delivere dt o th e mold

. O f course , thes e technologie s hav e
14 Composites Fabricationl]\ine 199 8 thei r limitations

. Non e can practicall y b e use dfo r ge l coat , sinc e thi s materia l need s t o b e applie di n avery uniformlaye r tha t ca n b e accomplishe donl y wit h atomize d spray . Pressure-fe droller s ma y no t trans
fe r resi n t o th e mol dfas t

enoug h t o kee p u p wit h productio n i n man y shops , and , lik e resi n impregnation , are no t useful wit h choppe droving

. Flow-applicator s ma y hav e problem s wit h filledresi n systems , althoug h supplier s ar e workin g t o overcom e thi s limitation

. An d 

### Suppressants

have to be
matched to the resin system employed, and

they may not
work as effectively

with filled
resin systems.
pressure-fe drollers an dflow-applicators ma y requir e additiona l roll-ou t t o satisfac

toril y we t glass

. Despit e th e potentia l limitations , however , thes e technologie s promis e significan t

emissio n reduction s over th e traditiona l spra y applicatio n o f resin , an d ar e finding increasin g acceptanc e i n th e industry

. An y molde r

usin g atomize d spra y applicatio n ofresi n shoul dgiv e flow applicators , pressur e fe

drollers , an dresi n impregnator s aseriou s loo k 

### Suppressant

s A secon dwa y o f

reducin g contac t

o f resi n wit h air i s throug h th e us e o f

suppres sants
. Thes e materials , whic h are typicall y waxes , formalayer

o n th e surfac e o f

th e resi n whil e i t

i s curing

. Thi s layer

reduce s th e evaporatio n o f

styrene
. Suppressant s work

onl y whe n th e resi n i s lef

t undisturbed , s o tha t

th e layer o f wa x ca n b e forme do n th e surface

. Durin g resi n applicatio n an droll-out , fres h resi n an dstyren e i s continuousl y expose dt o th e air , an dsuppressant s are no t effectiv e i n reducin g emissions

. In a typical spray-up/roll-out/curin g process , however , abou t

one-quarte r

o f che


## 1 emission s come s fro mth e curin g stage ,

an dsuppressan t

ca n b e very effectiv e i n reducin g dies e emissions

. Suppressant s hav e t o b e matche dt o th e resi n syste memployed , an dthe y ma y no t wor k a s effectively wit h filledresi n systems
. Resi n an dsuppressan t supplier s ca n hel p selec t

th e mos t effectiv e combi

nation s o f

materials

. Finally , wit h suppressants , molder s hav e ofte n foun ddia t

die y nee dt o san do r grin ddi e surfac e o f

part s i f additiona l laminat e layer s are t o b e applie dafte r curing

. Thi s proble mwit h "secondar y bonding " i s becaus e th e wax y suppressan c layer o n th e surfac e o f

th e part , whic h reduce dstyren e evaporatio n durin g curing , ca n late r ac t like areleas e agen t

an dpreven t adequat e bondin g betwee n th e laminat e an ddi e subsequenti y applie dresin

. 

### Controlled spra

y Fo r th e atomize dspra y applicatio n o f resi n o r ge l coat , th e us e o f

acontrolle d spra y progra mi s on e ofth e mos t effectiv e way s o f reducin g th e surfac e are ao f th e we t resin , thereb y reducin g contac t o f resi n wit h air , an dconsequentl y reducin g emissions

. A controlle dspray progra m consist s o f

thre e components :
• prope r calibratio n o f

spray guns , s o tha t th e lowes t

ti p pressur e tha t

stil l deliver s a n adequat e fa

n patter n i s use d (highe r pressure s resul t

i n muc h mor e "misting " o f

resin an devaporatio n o f styrene) ;
• trainin g operator s t o handl e spra y gun s an dappl y resi n usin g technique s designe dt o minimiz e overspray ; an d

• us e o f containmen t

flanges at

mol d perimeters , whic h preven t th e deposi

tio n o f hig h surfac e are aresi n layer s o n th e floo r

an dwalls

. Actually , controlle dspray ca n fit int o bot h o f ou r general emissio n reductio n technologies : acontrolle dspray proces s use s les s resi n an dstyren e —becaus e mor e i f i r i s delivere dt o th e mol d—an d i t minimize s th e exposur e ofresi n t o air

. Whil e implementin g acontrolle d spra y progra mwil l requir e employe e train

in g (includin g regula

r refreshe r training ) an dsom e modificatio n o f mold s (t o ad d th e flanges), di e investmen t will b e quickl y recovere dthroug h saving s i n resi n us e an d improve dhousekeeping

. Honestly , every on e doin g atomize dspray applicatio n o f resi n o r ge l coat shoul db e usin g controlle d spray . Fo r

mor e informatio n abou t thi sP. 5

hnology , call CF A an das k for acop y o f : Controlle dSpray Handbook

. 

### rflo w managemen t : ha s alimite dabilit y t o hol dstyren e .or , an donc e thi s limi t

i s reached , n o ire styren e wil l evaporate , unles s th e rene-lade n ai r

i s replace dwit h fresh air

. i n theory , allowin g astyrene-lade n e r o f ai r t o remai n a t

th e resi n surfac e i reduc e styren e evaporation

. I n practice , airflo w mus t b e reduce d ver y lo w level s t o achiev e an y rea l pac t o n styren e evaporation

. Th e CF A :in g progra mshowe dtha t reducin g lo w acros s we t

ope n mold s di dno t lificantl y reduc e emission s i n ope n lding , probabl y becaus e airflo w ca n : b e practicall y reduce denoug h over a n : n mold

. I n othe r processes , however , emissio n uction s o f

u p t o 60 % ca n b e achieved , tin g ha s show n significan t emissio n uction s fromth e us e o f cover s o r losure s ove r

we t proces s area s i n trusion , continuou s lamination , an d C compounding

. An dtest s wit h trusio n line s hav e show n emissio n iction s jus t

b y reducin g genera l venti

- > n flows. O f course , user s o f

thi s technolog y st stil l compl y wit h occupationa l osur e limits

. Th e enclosure s irione dabov e typicall y allo w acces s t o proces s onl y throug h hand-size d r s ("hand-ways " rathe r

tha n "man

s")

. An dgeneral ventilatio n can b e ice donl y if

. occupationa l exposur e I s ar e stil l belo w th e require dlevels

. Finally , ai r

flo w managemen t

— ug h th e us e o f

lid s o r cover s —i s als o effectiv e i n reducin g emission s fro m i mixing , storage , an dtransfe r vessels

. 

### se d moldin g las t technolog y tha t

we'l l conside r

for cin g styren e los s fro maproces s i s : dmolding , whic h include s vacuu m molding , resi n infusion , RTM , an d pressio n molding

. Thes e technolo

zzn hav e ver

y lo w emissions

. However , proces s economie s ofte n el y limi t th e applicatio n o f

thes e lologies

. Compressio n moldin g i s jl e onl y whe n larg e productio n run s eede d(say , 50,00 0 automotiv e hood s 'ear) , an dwher e th e capita l i s avail

t o pay for

th e larg e presse s an d >le x molds

. Vacuu mba g moldin g an dresi n infusion , however , ar e often usefu l an deconomicall y feasibl e fo r product s mad e wit h ope n molding , especiall y wher e hig h volum e productio n i s no t needed

. An dwhil e RT M (resi n transfe r molding ) doe s requir e special mold s an dothe r

equipment , th e invest

men t i s muc h les s tha n tha t

require dfo

r compressio n molding

. 

### Conclusio n Severa l technologie s ar e prove n an davail

abl e fo r reducin g emission s o f styren e fromcomposit e manufacturin g processes . Whil e mos t

hav e som e limitations , almos t ever y composit e manufacture r will finda t leas t

on e tha t wil l wor k

wit h hi s process . An dth e improve dworkin g conditions , reduce denvironmenta l footprint , an d goodwil l t o b e gaine dfromworker s an d neighbors , mak e th e effor t t o investigat e an dus e thes e technologie s agoo dinvest

ment , ft John Schweitzer

is the Composites Fabricators association's Senior Director of Government

Affairs. 

# I fyou' d lik e t o joi n thi s elit e group.. . i t i s possible . CAL L FREES , INC . 1-800-978-373 3 

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