Tiêu chuẩn iso tr 21275 2017

This document comprises two main part ; the firs pro ides a g ene al o e view of the key ar as of rub e t ech olo y an the se on pro ides an ext ensive r view of in-house an ext ernal lt

Rubber — Comprehensi ve review of

Ca utch uc — Ex men e xh ustifde la comp sition et de la n tur des

f mées de proce ss da s l’industrie du ca utch uc

Refer ence n mb r

ISO/TR 2 275:2 17(E)

Fir t edition

2 17-0

COPYRIGHT PROTECTED DOCUMENT

© ISO 2017, P blshed in Sw itz rlan

A ll rig hts r eserved Unles otherw ise spe ified, nopar of this p blc tion ma y be r epr od c d or utilz d otherw ise in an form

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written permis ion Permis ion c n be req esed from either ISO at the ad r es below or ISO’s member bod y in the c u try of

F reword v

Introduction vi

1 Sc ope 1

2 Nor mati ve r eferenc es 1

3 Terms an definitions 1

4 Overview of the r ubber ind str y 8

4.1 General 8

4.2 Rub e comp nent pr od ction pr oc s es 8

4.3 Gene ic rub e types 1

4.4 Rub e chemicals and additives 1

4.5 Me hanistic chemis ry of rub e vulcanization 1

4.5.1 Generalty 1

4.5.2 Sulfur-ac eler ated cur e sys ems .1

4.5.3 Per ox ide-b sed cur e sys ems 14

4.5.4 Metal ox ides 14

4.5.5 Othe vulcanizing sys ems 14

4.6 Efe t of elev ted temperatur e on rub e y p lyme s and rub e ad itives 1

5 Definitio of r ub e fumes 15

6 Nature and c omposition of rubbe fumes 16

6.1 General 1

6.2 Key comp nents ofrub e fumesan their orig in 1

6.3 Trap ing an analysisof rub e fumes 1

6.3.1 General 1

6.3.2 Characte ization s u ies car ied out in factory envir onments 1

6.3.3 Characte ization s u ies car ied out u de la oratory con itions 1

6.4 Chang es in rub e te h olog y that ha ve influenc d the natur e an comp sition of rub e fumes an impr oved the pr ote tion of wor ke s in the in us ry 1

6.4.1 General 1

6.4.2 Overal tr en in rub e wor ke s’ ex posur e to total rub e fumes

1 6.4.3 Poly romatic hydr ocar bons 1

6.4.4 Nitrosamines 1

6.4.5 Siane coupl ng ag ent an r esor cinol s e l cord co ting ag ent 1

7 Factor safectin the var iabiity of r ubbe fumes 19

7.1 General 1

7.2 Influenc of the rub e comp u d formulation on the comp sition of rub e fumes 2

7.3 Influenc of difer ent man facturing pr oc s es on rub e fumes 2

7.4 Influenc of difer ent pr oc s ing temperatur es on the comp sition of rub e fumes 2

8 Review of lterature o the c ompositio and nature of r ub er proc es fumes 22 8.1 Compr ehensive lteratur e search 2

8.1.1 General 2

8.1.2 Rub e fumesdata o tained fr om factory atmospheres 2

8.1.3 Rub e fumesdata o tained b la or atory studies 3

8.1.4 Research on samplng and analysis te h iq es for rub e fumes .3

8.1.5 Influenc of rub e ad itives on the composition of rub e fumes 3

8.1.6 Wor k car ied out at Ra ra Te h olog y Ltd 40

8.2 Othe sources of information 41

8.2.1 General 41

8.2.2 S ar ch strateg y for ex te nal data ases 42

8.2.3 Chemical a s ract r esult 42

8.2.4 General POLL U A B an NTSI datab se r esult 43

8.2.5 S ar ch of in ustry-r elev nt publcations, g ove nment publcations an

r elev nt websites 43

9 Summary of the finding of the lterature review 44

10 Co clusions 45

A nne x A (informative)A bbr eviated terms 47

Biblog raph y 49

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ISO cola orat es closely with the Int ernational Ele trot ech ical C mmis ion (IEC) on al matt ers of

ele trot ech ical s an ardization

The proc d r s used t o develo this document an those int en ed for it furthe maint enanc ar

desc ibed in the ISO/IEC Dir ctives, Part 1 In p rticular, the dife ent a pro al c it eria ne ded for the

dife ent ty es of ISO document should be not ed This document was draft ed in ac ordanc with the

edit orial rules of the ISO/IEC Dir ctives, Part 2 ( e www iso org dir ctives)

A tt ention is drawn t o the p s ibi ity that ome of the element of this document ma be the subje t of

p t ent right ISO shal not be held r sponsible for identifying any or al such pat ent right Detais of

any p t ent right identif ied d ring the develo ment of the document wi be in the Introd ction an / r

on the ISO ls of p t ent de larations r c ived ( e www iso org p t ent )

Any trade name used in this document is information given for the convenienc of use s an does not

cons itut e an en orsement

For an ex lanation on the meaning of ISO spe ific terms an ex r s ions r lated to conformity as es ment,

as wel as information a out ISO’s adhe enc to the Wor ld Trade Org nization (WTO) principles in the

Te h ical Bar ie s to Trade (TBT) se the folowing URL: www iso org / iso/ for word html

This document waspr p r d b Te h ical Committ ee ISO/TC 45, Ru be a d ru be produc ts

Fumes emitt ed d ring the rub e man facturing proc s es we e the t opic of many s u ies This

compr hensive s u y was u de taken t o compie an r view publshed data with r spe t t o rub e

fume emis ions in the workplac This r view has pro ided a compr hensive b n of t ech ical data

for dis emination an furthe deb t e It has as es ed l t eratur r g rding the chemical composition

of rub e fumes in man facturing from a compr hensive rang e of proc s es It has be n p s ulat ed

that fume emis ions from rub e comp u d vulcanization can be conside ed a single chemical entity,

cit ed as p sing a car inog enic risk t o h man health Although many s u ies ha e tried t o charact eriz

rub e fume emis ions, the e is no known concise s u y that pro ides a rational ex lanation for this

conclusion This s u y has t est ed this p s ulation an pro ided an insight as t o w hethe it is a sou d

conclusion

The aim of this proje t was t o ev luat e, on a basis of sou d scientific lt eratur , w hethe it is

scientificaly ro us t o conside “ rub e fumes” as a homog eneous entity from a chemical p int of view

an , mor imp rtantly, in r lation t o measur ment an control of oc up tional ex osur risk for the

rub e in us ry as a w hole

An ext ensive lt eratur r view aimed at pro iding a compi ation of lt eratur r lat ed t o rub e fume

emis ions, this s u y has conc ntrat ed on the chemical comp sitional aspe t of rub e fumes only an

not on the t oxicolo ical or epidemiolo ical aspe t

In ad ition, although rub e d s an rub e fumes ar being conside ed b the EU for a p t ential

incorporation in the sco e of the C r inog ensDir ctive, this s u y has only conside ed rub e fumes

This document pro ides detai ed information on the s u y car ied out, the r sult o tained from the

lt eratur r view s an the conclusions drawn from this information

This document comprises two main part ; the firs pro ides a g ene al o e view of the key ar as of

rub e t ech olo y an the se on pro ides an ext ensive r view of in-house an ext ernal lt eratur on

the comp sition an natur of rub e proc s fumes

Natural rub e (NR) has be n k own t o the civi z d world sinc a out 149 w hen early Euro ean

ex lor rs fou d natives of Haiti pla ing with b l s made from the exu at es of a tr e caled “cau-uch ”

The t erm “ rub e ” was coined much lat er b the E glsh chemis J.B Pries ly for it a i ty t o e ase

lead penci marks The Fr nch scientis De La C n amine f irs introd c d NR t o Euro e in 1 3 an

publ shed his o se v tions on the mat erial in 1 45 Ind s rial a plcation of rub e only oc ur ed aft er

Charles Go dyear in 1 41 disco e ed the proc s t ermed “vulcanization” , w hich conve t ed the rub e

t o a mor s a le an useful mat erial, that p ved the wa for the growth of the mode n in us ry

Synthetic rub e s we e f irs prod c d in Ge many in the 1 3 s, an d ring the S con World War

w hen the sup ly of natural rub e was int er upt ed, methods we e develo ed for the bulk prod ction

of synthetic rub e s Styr ne butadiene rub e ( SBR) was one of the f irs synthetic rub e s t o be

develo ed and man factur d in high v lume in the 1 40s, mainly for the prod ction of tyr san in an

att empt t o mat ch the pro e ties of natural rub e Sinc that time, many dife ent synthetic rub e s

ha e be n develo ed t o alow the use of rub e in a ve y wide v riety of environment an a plcations

Ove the years, the imp rtanc ofrub e t o mode n l fe has cons antly inc eased This is not alway s

immediat ely a p r nt be ause rub e comp nent ar oft en not colourful, eye cat ching or ar used in

a plcations w he e they ar not r adiy visible Natural an synthetic rub e compoun s ar used in

a highly dive se rang e of rub e prod ct w hich ar man factur d throughout the world for v rious

se t ors of in us ry an for a v riety of en use s, inclu ing, but not ex clusively, a ut omotive, ae ospac ,

medical/ harmac utical, defenc , comme cial, g ene al ind s rial an othe s

Of the se t ors w he e rub e is used, the aut omotive ind s ry is of p rticular imp rtanc sinc tyr an

tyr prod ct ac ount for a pro imat ely 6 % of the synthetic rub e an ~7 % of the natural rub e

used t oda

Ta le 1 pro ides an o e view of the dive se rang e of rub e component made from g ene al

man facturing proc s es an dip ed lat ex t ech olo y The ls of component isb no means exhaus ive

but helps highlght the dive se ar as and prod ct in w hich rub e is used

Table 1 — Rang e of rubber compo ents

T res pas eng er car , trucks, racing vehicles, cycles, of-ro d tyres, in er tub s, curing

blad er

Conveyor/

Transmis ion b lting

ste lcord conveyor b lting, repair material for conveyor b lting, s raper ,

min-ing conveyor , V-b lts, flat b lts, sy chronous b lts

In ustrial hoses water hoses, high-pres ure hoses, welding hoses, hydraulic hoses, spiral hoses,

ofshore hoses, oil hoses, chemical hoses

A utomotive prod cts co lant hoses, fuel hoses, se ls an g skets, antivibration mou ts, hydraulic

hoses,fuel injector , timing b lts, win ow an do r chan eling, transmis ion

an engine components, wiper blades, e haust hang r

General mouldings/

She ting

moulded se ls an g skets, antivibration prod cts, flo r coverings, she ting,

tub rings, ro f ing layer , subsoil water she ting, rol er coverings, protection

linings, moulded mic o-celular prod cts, composit e prof iles,rub erized fa ric,

mic o-cel ular rub er /prof iles, wire an ca le jackets an insulations, glas

se lants, p mp impelor , ro f membranes, pon liner , rail mou ts, bridg e

b arings, military vehicle track pads

Medical/

P armaceutical prod cts

surgical gloves, medical tubing, MDI valve g skets, cathet er , dialysis prod cts,

surgical implants, prostheses, contraceptives, so ther ,b by fe ding te ts an

bre st caps, blo d transfusion tubing an valves, medical an antistatic she ting

an membranes, masks an respirat or

Clothing b ots/fo twear, protective suits,household gloves, in ustrial gloves, fo twear/

b ot he ls an soling, cel ular rub er soles, wet suits, diving suits, co ted fa

-ric , sports fo twear an clothing

Fo d contact prod cts fo d transportation (e.g conveyer b lts, hoses an tubing), fo d han ling

(gloves), pipe an machinery components (se ls, g skets, fle ible con ector an

diap ra m/ utt erfly valves), p mping sy stem components (pro res ive cavity

p mps stat or , diap ra m p mps), plat e he t ex chang r g skets, se ls/ askets

for cans, b t les an closures

Pota le wat er prod cts pipe se ls an g skets, hoses, linings of p mps an valves, tap washer ,

mem-branes in pipes an f ilter , co tings on proces plant, tan linings

Mis el ane us prod cts ad esives, rub erized asp alt, high vacu m an radiation components, carpet

b cking, late thre d, se lants an caulking, toys

It is important that the r ade of this document conclu es that the rub e mat erial used t o make

any p rticular prod ct is not a single entity but is a complex compoun ed mat erial r fe r d t o as a

“comp un ” or “ ormulation” , w hich ma contain a larg e n mbe of es ential chemical ingr dient

These ingr dient wi l inclu e the b se rub e p lyme (), r infor ing an non-r infor ing particulat e

file s, proc s oi s, vulcanizing ag ent , prot ective ag ent , proc s aids, et c (al of w hich ar a aia le

in many ty es an grades from many sup le s an can be inclu ed at dife ent levels) The comp ny or

in ivid al w ho designs a rub e formulation for a spe ific prod ct hasa v s n mbe of ingr dient t o

cho se from an as such, many formulations ar the efor pos ible for a spe ific rub e prod ct

The proc s ing rout e b w hich the majority of rub e component ar man factur d inclu es mixing

the ingr dient t og ethe in a controled man e t o prod c a rub e “comp u d” or “ mix sha ing of

the mix ed comp u d t o give the desir d sha e or form, then “vulcanizing” (also k own as “c os l n ing”

an “curing” the comp u d t o conve t it t o a con ition w he e it has pe manent pro e ties an sha e

The ty e of rub e mat erials an man facturing proc s es used wi l depend up n the in ivid al

prod ct an ar desc ibed in this document Many of the man facturing proc s es inv lve g ene ating

heat in the rub e compoun w he e volatie spe ies such as “ umes”can be r leased from it

The larg e dive sity in b th the rub e formulations a ai a le an the man facturing proc s es used

can the efor p t entialy giverise t o a highly dive se rang e of spe ies ev lved

In orde t o as is the r ade t o u de s an the t erminolo y as ociat ed with the rub e t ech olo y in

thisdocument, a glos ary of t erms is inclu ed in An ex A

Rubber — Comprehensi ve review ofthe c omposition and

This document, b sed on 9 publcations, gives an o e view of w hat is the composition of the fumes

emitt ed d ring the rub e man facturing proc s es The r sult o tained con rm that rub e fumes

ar a complex an v ria le mix of chemicals w hich ha e a wide rang e of pos ible sour es an origins,

inclu ing chemicals g ene at ed from the chemical r actions oc ur ing in the rub e comp u ds d ring

proc s ing an curing Some of these chemical subs anc s can be hazardous, othe s ar not This

document demons rat es the ne d for Int ernational Stan ards t o q alfy an q antify the hazardous

chemicals t o w hich theo e at ors in the fact ories prod cing rub e articles can be ex osed t o, alowing

the identification an mitig tion of p t ential health risks

2 Normati ve r eferences

The e ar no normative r fe enc s in this document

3 Terms and definitions

F or the purposes of this document, the folowing t ermsand definitions a ply

ISO an IEC maintain t erminolo ical data ases for use in s an ardization at the folowing ad r s es:

— IECEle tro edia: a aia le at ht p:/ www ele tro edia org

— ISO Onlne brow sing plat orm:a ai a le at ht p:/ www iso org o p

3.1

ac elerator

comp u ding ingr dient used in smal amou t with a vulcanizing ag ent t o inc ease the spe d of

vulcanization and/ r en anc the physical pro e ties of the vulcanizat e

antide radant

comp u ding ingr dient used t o r tard det erioration b ag eing

Not e 1 t o entry: Antide radant is a g neric term for certain ad itives such as antio idants, antiozonants, wax es

an other protective mat erials

simples membe of the aromatic se ies of hydrocarbons

Not e 1 to entry: It is colourles liq id with a b.p of 8 °C an is used in the man facture of man org nic

subs anc , usualy in lq id form, co t ed ont o anothe mat erial an used t o prod c a g ood b n

betwe n the mat erial an rub e

[ SOURCE:ISO 1 8 :2 1 , 2.54, modif ied — Not e 1 t o entry has be n delet ed.]

g s used in the man factur ofpoly utadiene rub e an as one of theco olyme s in the man factur

of s yr ne-butadiene an nitrie rub e s

3.12

calender

machine with two or mor es entialy p ralel rol s, o e ating at sele t ed surfac spe ds, nips an

t empe atur s, for such o e ations as she ting, laminating, skim co ting (t op ing) an friction co ting

of a prod ct t o a controled thick es an / r controled surfac charact eris ics

[ SOURCE:ISO 1 8 :2 1 , 2.6 ]

carbo black

comp u ding ingr dient consis ing es ential y of mor than 9 % elemental carb n in the form of

near-sphe ical particles with major diamet ers les than 1 µm, g ene al y co lesc d int o a gr g t es

Note 1t o entry: Carb n black is prod ced by incomplete burning or thermal decomposition of hydrocarb ns

[ SOURCE:ISO 1 8 :2 1 , 2.6 ]

3.1

chloroh drin rub er

clas of synthetic elast ome sb sed on epichlorohydrin

3.1

chloroprene rubber

CR

elast ome ic mat erials composed of chloro r ne

Note 1 t o entry: It has fair to g od resistance t o petroleum-b sed fluids an g od resistance t o ozone an

elast ome made b subs ituting chlorine an sulfony l chloride groups int o polyethy lene

Note 1t o entry: T e mat erial is b st k own by the trade name Hy alon (Du ont)

3.17

intimat e mixtur of a rub e or rub e s or othe p lymer-forming mat erials with al the ingr dient

ne es ary for the f inished prod ct

Note 1t o entry: T e term rub er is sometimes used to me n compou d, but his use is deprecat ed

[ SOURCE:ISO 1 8 :2 1 , 2.9 ]

3.1

compo nding

develo ment of rub e comp un s w hich wi l efe tively withs an the con itions un e w hich the

prod ct made from them ar t o be used

Note 1 to entry: T e mix es so developed must b capa le of b ing proces ed in the factory without u d e

diff iculty

Note 2 to entry: T e term is also ap lied to the as embling of elastomer an compou ding ingredients re d

for mixing

3.1 9

compo nding ingredient

subs anc ad ed t o a rub e or rub e lat ex t o form a mix

[ SOURCE:ISO 1 8 :2 1 , 2.9 ]

3.20

compres io moulding

moulding proc s in w hich the blank is plac d dir ctly in the mould ca ity an compr s ed t o sha e b

closur of the mould

[ SOURCE:ISO 1 8 :2 1 , 2.9 ]

co vey r belting

belting used mainly in the transmis ion of mat erials, although inc easing use is being made of convey r

belting in thetransportation of p s eng ers

a plcation of ac ele at ors an t empe atur for the es a l shment of chemical c os l n s betwe n

mac omole ules of rub e

Not e 1 to entry: This term is sy on mous with v lcanization only in case of mix es containing sulfur S me other

chemicals are also used to esta lish these c os lin , for e ample, pero ide

Not e 2t o entry: The word curing is g neral y paired with a specif ic method, e.g pres curing, open ste m curing,

cold curing

3.24

disper io

< ct of> dis ribution of one or mor ingr dient int o a rub e , a rub e blen or a contin um mat erial,

b the a plcation of shearing for es, in orde t o confe o timum and uniform pro e ties

b n in w hich two v lency b nds lnk two at oms in a mole ule

Not e 1 to entry: It is ty ical of compou ds showing u saturation, such as eth lene A double b n do s not

in icate e tra strength of the b n but rather chemical insta ility an re ctivity

3.26

elastomer

mac omole ular mat erial w hich r turns ra idly t o a pro imat ely it initial dimensions an sha e aft er

subs antial deformation b a weak s r s an r lease of the s r s

machine w hich, through the use of a sc ew or a hydraulc ram, contin ously sha es a mat erial b for ing

it through a die or dies

[ SOURCE:ISO 1 8 :2 1 , 2.176]

fi ler

sold comp u ding ingr dient, in particulat e form, w hich ma be ad ed in r latively larg e pro ortions

t o a rub e or rub e lat ex for t ech ical or e onomic purp ses

[ SOURCE:ISO 1 8 :2 1 , 2.1 4 ]

3.30

injectio mo lding

moulding proc s in w hich a rub e comp u d is for ed int o a closed mould from a sep rat e chambe ,

b a pr s ur w hich is in epen ent of the mould clamping for e

[ SOURCE:ISO 1 8 :2 1 , 2.242]

3.31

internal mix er

machine with t empe atur controls containing one or mor rot ors o e ating in a closed ca ity used t o

mas icat e an / r t o incorp rat e an dispe se comp un ing ingr dient int o the rub e

lq id hydrocarb n with b i ing p int 34°C

Note 1 to entry: It is re arded as the u it molecule of natural rub er, which is p ly i s op e e (3.43) Sy thetic

polyisoprene is marketed u der a variety of trade names

machine with two cou t er-rotating rols, fr q ently heat ed or co led, usualy driven at dife ent spe ds,

an ha ing an adjus a le nip for mas ication, mixing, blen ing, warm-up or she ting

[ SOURCE:ISO 1 8 :2 1 , 2.2 4 ]

3.35

mix

mixtur of rub e in any form with othe comp u ding ingr dient

Note 1t o entry: T e term can ap ly to an incomplet e rub er compou d

[ SOURCE:ISO 1 8 :2 1 , 2.2 8]

3.36

mixer

machine w hich, through the action of me hanical work ( hear), incorp rat es and dispe ses compoun ing

ingr dient int o rub e ( ) t o form a mix or compoun

[ SOURCE:ISO 1 8 :2 1 , 2.2 9]

Not e 1t o entry: Naturaly oc ur ing polyisoprene are natural rub er (c i s -form) an gut a per ha (tr ns-form).

Not e 2 to entry: T e use of stere specif ic cataly sts has made pos ible the man facture of sy thetic c i s

-polyisoprene an tr ns -polyisoprene b th of which are availa le commer ialy

3.44

polymer

subs anc comp sed of mole ules charact eriz d b the multiple r petition of one or mor spe ies of

at oms or groups of at oms (cons itutional unit ) l nked t o each othe in amount sufficient t o pro ide

a set of pro e ties that do not v ry markedly with the ad ition or r mo al of one or a few of the

cons itutional u it

[ SOURCE:ISO 1 8 :2 1 , 2.341]

3.4

proces ing

v riety of o e ations r q ir d t o conve t a raw elast ome int o finished prod ct

Not e 1 t o entry: Proces ing inclu e calen ering, c omp u din (3.1 ), c rin (3.2 ), e trusion, mastication,

mixing, spre ding

3.46

resin cure

vulcanization of elast ome s efe t ed b the incorporation in the compoun of c rtain p lyme ic r sins

de ived from the con ensation of formaldehydewith 4-alky l phenols

Not e 1t o entry: Most freq ently used with buty l an E DM compou ds for en anced he t resistance

<prod ct > famiy of p lyme ic mat erials w hich ar flexible an elas ic

Note 1 t o entry: R ub er can b substantialy deformed u der stres , but recover q ickly t o ne r its original

shape when the stres is removed It is usualy made from a mixture of materials (solid or liq id), an in most

prod cts the b se polymer is c os linked by either chemical or p y sical lin s

[ SOURCE:ISO 1 8 :2 1 , 2.3 4 ]

3.49

rubber

<raw mat erial> natural or synthetic elas ic polyme (elast ome ) w hich forms the b sis of the comp u d

used in many rub e prod ct

p ly rg nosi o ane, ha ing a back bone s ructur consis ing of alt ernating si cone an o y g en at oms

with org nic groups, usual y methy l, viny l or pheny l radicals, at ached t o the si cone membe

Note 1t o entry: It is an elastomer of the silicone family

proc s , usual y inv lving heat, in w hich rub e , through a chang e in it chemical s ructur (for

ex mple, c os lnking), is conve t ed t o a con ition in w hich the elas ic pro e ties ar confe r d or r

-es a lshed or impro ed or ext en ed o e a gr at er rang e of t empe atur s

Note 1t o entry: In some cases, the proces is car ied t o a point where the substance b comes rigid, e.g e onite

zinc o ide

activ t or in rub e compou ds containing org nic ac ele at ors

4 Ov rview of the rubber industry

This clause is int en ed t o give the r ade a brief o e view of rub e t echnolo y in orde t o pro ide some

es ential b ckgrou d information that wi l sup ort an inform non-t ech ical r ade s of the lt eratur

r view The o e view is broken down int o four spe ific ar as ( e 4.2 t o 4.5) as detaied below, an

encomp s es the ful spe trum of the rub e in us ry, with the fif h p rt ( e 4.6) co e ing the efe t of

elev t ed t empe atur on the b se p lyme san rub e ad itives

— R ub e comp nent prod ction proc s es

— Gene ic rub e ty es

— R ub e chemicals an ad itives

— Me hanis ic chemis ry of rub e vulcanization

— Efe t ofelev t ed t empe atur on rub e y p lyme s an rub e ad itives

4.2 Rubber component production pr oc es es

The wide dive sity of rub e component in the market is highlght ed in the Introd ction The rub e

prod ct man facturing in us ry can be divided int o four groups: 1) vehicle tyr s, 2) engine ring an

in us rial prod ct , 3)lat ex prod ct and 4 ) othe misc l aneousrub e prod ct

The man facturing proc s es inv lved in these in us ries ha e many simiarities but the e ar also

many dife enc s The dife enc s r lat e t o the raw mat erial (w hethe using NR or synthetic rub e ), the

ty es of chemical ad itives used in the rub e formulationsan the ty e of curing methods emplo ed

The main proc s ing s ag es for the majority of rub e component man factur d inv lve the folowing:

— Mixing: The f irs s ag e of the rub e man facturing proc s inv lves the prod ction of a rub e

formulation, (also k own as a “ mix” or “comp un ” Mixing is of c ucial an fu damental

imp rtanc t o the rub e in us ry The b se rub e sha e t o be ext en ed with a v riety of es ential

ingr dient inclu ing plas iciz rs, r infor ed with p rticulat e f il e s an imp rtant ad itives such

as ac ele at ors, curatives an prot ective ag ent , w hich al ne d t o be thoroughly dispe sed an

dis ribut ed befor the r sultant comp u d can be sha ed an vulcaniz d t o give an en prod ct

with adeq at e pro e ties Al these cannot be achieved without efe tive mixing

R ub e formulations v ry significantly in their comp sition depen ing up n the desir d

charact eris ics of the prod ct As many as 1 t o 2 dife ent ingr dient ma be used in a single

comp u d depen ing up n the p lyme ty e an a plcation fumes

The mixing eq ipment used t o prod c the rub e compoun s inclu es int ernal b t ch mix ers,

mixing mi s, contin ous int ernal mix ers and mixing extru e s The a pro riat e comp un ing

ingr dient for the formulation ar normal y weighed out in a comp u ding ar a or “drug” ro m

befor being lo ded int o the mix er at pr det ermined s ag es Howeve , it is also a practic , espe ialy

in the tyr man facturing in us ry, for ingr dient t o be sup led pr weighed b the sup le an

ad ed dir ctly int o themix er

— Sha ing o e ations: Inv lves proc s es t o conve t the mixed comp u d int o a suita le form/sha e

for the next s ag e of the proc s (e.g extrusion t o form profile sha es, calen e ing t o prod c

she t ed mat erial, mi ing t o form moulding blan s, han buiding, et c ).This wi l also inclu e the

proc s es w he e othe r infor ing mat erials, inclu ing st eel wire /cord or t exties ar combined

with the u cur d rub e comp u d befor being buit/ s embled int o the f inal prod ct befor

vulcanization

— Vulcanization: F or the v s majority of rub e prod ct a plcations (ex cept solution an lat ex

adhesives, put y-l ke prod ct , chewing gum-b sed prod ct an some forms of she ting), it is

ne es ary t o conve t rub e y mole ules int o a s a le thr e dimensional network so that r co e y

aft er deformation is es entialy complet e In la man t erms, the proc s conve t the rub e

comp u d int o a mat erial w hich has much mor s a le pro e ties o e it int en ed working

t empe atur rang e

To achieve this, it is ne es ary t o u de take an ir eve sible proc s of c os l n ing the p lyme

chains, w hich is k own as “vulcanization” , “c os l n ing” or “curing” In the majority of cases, this

oc urs b heating the rub e comp un at an elev t ed t empe atur t o ac ele at e the chemical

r action an b pr s urization of the mat erial t o consoldat e it

The actual c os lnking me hanisms wi l be discus ed in a lat er cla use

The spe if ic proc s method b w hich the prod ct is vulcaniz d wi depen on a n mbe of

fact ors, w hich ma inclu e formulation of the comp un , phy sical form of the prod ct r q ir d,

thepr senc of othe mat erials such as t extie an st eel r infor ement, an the siz ofthe prod ct

— Pos vulcanization proc s es:Othe proc s es w hich ma take plac aft er the vulcanization s ag e t o

achieve final form or pro e ties (e.g p s -curing, anci ary proc s es)

A g ene alz d flowchart for rub e prod ct man facturing is shown in Figur 1 t o pro ide the r ade

with some g ene al guidanc on the ty ical proc s es inv lved from raw mat erials t o f inal prod ct an

how they ar l nked t og ethe It mus be emphasiz d that theactual proc s rout e involved wi l depen

upon the actual prod ct being man factur d The efor , not al rub e prod ct wi r q ir al of the

proc s st eps shown in Figur 1

A n mbe of the rub e man facturing proc s st eps inv lve the g ene ation of heat or ha e heat a pled

t o them and the efor ha e the pro ensity for the g ene ation of rub e fumes or v laties from the

rub e comp u d being proc s ed The proc s es highlght ed in r d in Figur 1 in icat e w he e rub e

fumes wi l be mainly g ene at ed, w hi e those shown in pin in icat e w he e the e is also pot ential for

rub e fumes t o be g ene at ed, depen ing up n thepr cise o e ating con itions of the proc s

The fol owing p int should be taken int o ac ou t w hen conside ing the proc s es used t o man factur

rub e prod ct

a) The proc s rout es an actual proc s ing eq ipment emplo ed for each prod ct ty e wi l be

spe ific t o that prod ct

b) The mat erial mixing, sha ing an vulcanization proc s ing con itions ( inclu ing time an

t empe atur , et c ) emplo ed for a particular prod ct ar not tan ardiz d throughout the in us ry,

but wi depen on a n mbe of fact ors inclu ing p lyme ty e, formulation, proc s eq ipment

ty e, ag e an controls, prod ct iz an sha e

c) The main man facturing proc s es w he e fumes ar lkely t o be g ene at ed inclu e mixing,

moulding, vulcanization an p s curing The proc s es w he e fumesma be g ene at ed, depen ing

upon the rub e formulations and proc s ing con itions, inclu e calen e ing, blan pr p ration,

extrusion and spr ading

d) Some man facturing plant wi man factur single prod ct ty es with very few dife ent

comp u d formulation ty es uti izing the same proc s ing eq ipment

e) Othe man facturing plant ma prod c a larg e rang e of dife ent prod ct , uti zing a diverse

rang e of rub e comp u d ty es an formulations, w hich emplo a rang e of proc s ing rout es

pe tinent t o the prod ct

f) The mor mode n fact ories or plant situat ed in mor develo ed countries ma ha e mor

aut omation an a g ood level of ventiation for many of the rub e man facturing proc s es w hich

g ene at e fumes an w he e the e is les dir ct contact b the emplo e s In contras , within some of

the East ern or les -develo ed cou tries, the e wi l be signif icantly les aut omation combined with

olde proc s ing eq ipment, p or r ventiation an mor dir ct emplo e contact with the rub e

comp u d as it pas esthrough the proc s , al of w hich would ha e a dir ct influenc on the levels

an ty es of fumes pr sent

Figure 1 — General zed flowchart for rubbe prod ct manufacture

A flowchart for the g ene al proc s esinv lved in tyr man facturing is shown in Figur 2 In a simiar

man e t o Figur 1, the proc s es w he e rub e fumes wi be g ene at ed ar highlght ed with the r d

symb l, , an those w he e the e is also p t ential for rub e fumes t o be g ene at ed depen ing up n

the pr cise o e ating con itions ofthe proc s ar highl ght ed with a purple symb l,

pr oces wher e rub er fumes w il b g ener ated

pr oces wher e fumes ma y b g enerated depen ing u on actual con itions

Figure 2 — Tyre manufacture flowchart

4.3 Gener ic rubber types

The folowing l s identifies the main g ene ic rub e ty es a aia le in the market an gives their ISO

designation in bracket Each rub e has a uniq e chemical s ructur w hich has a dir ct influenc on

it in e ent chemical an phy sical pro e ties, proc s ing beha iour an the a pl cations an prod ct

— A cry lonitrie butadiene rub e (also k own as nitrie or NBR)

— Hydrog enat ed nitrie rub e (HNBR)

— Polychloro r ne (CR)

— Buty l rub e (I R) an halog enat ed buty l rub e (BI R /CI R)

— Ethy lene pro y lene rub e (EP/E DM)

— Epichlorohydrin rub e s (CO/ECO/ETER)

— Chlorinat ed p lyethy lene (CP , CM)

— Chlorosulfonat ed polyethy lene (CSM/CSPE)

— Poly c y lat e rub e s (ACM)

— Ethy lene-ac y lic rub e (EACM, AEM)

— Ethy lene-viny l ac tat e (EV , EAM)

— Si icone rub e s (MQ, VMQ, FVMQ, PVMQ)

— Fluorocarbon rub e s(FPM, FKM)

— Polyur thane (AU, EU, PU)

— Poly sulf ide rub e (OT, EOT)

The r ade should take not e that for each rub e ty e, the e is a signif icant n mbe of dife ent grades

a ai a le for sele tion from seve al p lyme man factur rs, each of w hich ma dife in the folowing

aspe t : sup le , p lyme mole ular weight an mole ular weight dis ribution, p lyme ization ty e,

p lyme ization s a i iz r, co-monome ty e an level, t ermonome ty e an cont ent, pr senc an

level of pr -ad ed carb n black f ile , pr senc an level of pr -ad ed proc s oi, et c In the case of

ethy lene pro y lene polyme s, for ex mple, the e ar o e 1 0dife ent grades a aia le

Al rub e prod ct ar es ential y made from compoun ed mat erials an each of the rub e ty es

ne ds t o be spe if icaly formulat ed with a rang e of othe es ential ad itives t o achieve a rub e

“comp un ” that has the desir d proc s ing an pro e ties r lat ed t o the prod ct man factur d

It should also be not ed that not only ar rub e s used in ivid aly, but ar oft en used in blen s w he e two

or even thr e rub e ty es ar mixed an blen ed t og ethe , a ain in v arious ratios, in orde t o achieve

the desir d prod ct pe formanc an pro e ties Tyr comp nent comp un s ar ex mples of this

Taking al of the a o e aspe t int o conside ation, it can be conclu ed that the larg e rang e of rub e

grades a ai a le c eat es the p s ibi ty for the rub e compoun e t o design an inf init e n mbe of

rub e formulations for any given prod ct or a plcation

Al of the fact orsmentioned a o e wi l influenc the br ak down prod ct prod c d w hen the rub e is

proc s ed

The rub e comp un e mus det ermine w hich rub e ty e is a pro riat e for a given a plcation

an as is with that sele tion proc s C nside ation has t o be given t o fact ors such as t empe atur

r sis anc an oi r sis anc of each rub e

4.4 Rubber chemicals and additi ves

Rub e prod ct ar man factur d from “compou ds” or “ ormulations” w hich can comprise a rang e

of es ential ingr dient ne es ary t o alow the mat erial t o be proc s ed satis act ori y an achieve the

pro e ties r q ir d in se vic When conside ing the man facturing of rub e comp nent , it mus

the efor be taken int o ac ou t that they ar “comp u ded” mat erials

The principal clas es of rub e compoun ing chemicals inclu e the folowing:

— rub e s ( e 4.3);

— vulcanization ac ele at ors;

— activ t ors, r tarde s an inhibit ors;

— misc laneous ad itives.

Each of these clas es of mat erials play s a vital role in the rub e compou d, and within each clas of

ingr dient, the e is a wide rang eof dife ent chemical comp u ds a ai a le on the market

In conside ing the rub e chemicals used in the rub e in us ry, the folowing should be taken int o

ac ou t in r lation t o rub e fumes g ene ation

— R ub e prod ct comprise mat erials w hich can contain a wide rang e of chemical ad itives

— Although the e ar g ene al guidel nes for design of rub e comp u ds in r g rd t o the ingr dient

used, the f inal formulation depen s up n the know ledg e of each rub e comp u de The highly

dive se clas esan rang es of ingr dient a ai a le mean that he ear no “ tan ard”formulations

for any one prod ct or comp nent ; the efor , the e ar p t ential y an infinit e n mbe of rub e

formulations on the market

— W ithin each clas of ingr dient , the e ar n me ous man factur rs ofe ing a dive se rang e of

additives, w hich ar not chemicaly identical, ad ing t o the rang e of rub e formulations pos ible

— Depen ing on the rub e ty e an a plcation, the n mbe of ingr dient used in a rub e

comp u d can v ry from 4 or 5 up t o 1 t o 2 dife ent ingr dient , with diene-b sed rub e

containing the highes n mbe s of ingr dient Whe eas, mor spe ialz d rub e s such as si icone

an fluorocarb ns contain the leas

— It is also common practic t o use mor than one ingr dient from a p rticular clas in a formulation

t o achieve the desir d proc s ing an final pro e ties, w hich ad s t o the diversity of comp u ds

a ai a le (e.g two or mor ac ele at ors, antidegradant , carb n black file s, black an mine al

f ile s, et c )

4.5 Mechanistic chemistry of r ubber vulcanization

4.5.1 Generalty

The rang e of rub e p lyme s a aia le, as wel asthe significant dife enc s in their chemical s ructur s

is desc ibed in 4.3 As a r sult of these dife enc s, not al of the rub e ty es can be c os l nked b a

single ty e of cur sy st em, an the efor , the syst em used t o c os lnk them wi be dir ctly r lat ed t o

the in ivid al chemical s ructur of the rub e in q es ion The fact that the cur sy st em chemis ry

is markedly dife ent for each ty e wi also mean that the br akdown prod ct from comp u ds

containing these dife ent cur sy st ems wi l also v ry

The c os lnking sy st ems a aia le ar discus ed in 4.5.2t o 4.5.5

4.5.2 Sulfur-ac c elerated cur e systems

A ve y larg e pro ortion of rub e prod ct ar b sed on comp u ds prod c d using u saturat ed

(diene) rub e s Their chemical s ructur s contain double b n s throughout the p lyme chains that

pro ide r active sit es through w hich the c os l n ing r action b formation of co alent b n s takes

plac Due t o the pr senc of these r active sit es, c os l n ing using ac ele at ed sulfur sy st ems is

p s iblean these sy st ems dominat e much of themarket

The chemis ry of sulfur vulcanization is highly complex an even t oda , only the main s ag es ar pro en

an the e is s i l much t o be u de st ood a out he efe t of v rious cur sy st em ad itives

4.5.3 P erox ide-based cure systems

In t erms of v lume prod ction, the n mbe of rub e prod ct containing pe o ide-b sed curing

sy st ems is conside a ly lowe than those containing sulfur-b sed syst ems

The rub e ty es that contain no unsaturation in their p lyme s ructur , known assaturat ed rub e s,

cannot be c os lnked using sulfur and the efor , the only practical wa of vulcanizing saturat ed rub e

is b use of a fr e radical g ene ating t echniq e The e ar a rang e of rub e ty es ca a le of being

c os lnked with pe o ides, w hich inclu es saturat ed an some u saturat ed rub e s lst ed in Ta le 2

Table 2— Rang e of rubber types capable of being c os l nked with pero ides

Pero ide c os ln ing pos ible for:

HNBR — Hydro enated b tadiene a ry lo itrie ru be EBA — Eth lene b ty l a rylate

Pero ide c os ln ing pos ible with blen s of:

Pero ide c os ln ing lmit ed or impos ible for:

CIR — C loro uty l ru be

As with sulfur vulcanization, c os l n ing using pe o ides is also chemicaly ve y complex and has

be n s u ied b many workers o e a n mbe of years Be ause of the v riety of r actions, widely

dife ent beha iour is said t o oc ur with dife ent rub e s an dife ent pe o ides, w hie the pr senc

of co-ag ent can ha e conside a le influenc The br ak down prod ct from these cur sy st ems ar

the efor dife ent from the othe cur sy st ems

4.5.4 Metal ox ides

The pr senc of halog ens (chlorine, bromine or fluorine) along the polyme chain of u saturat ed

rub e s t en t o “deactiv t e” the double b n , meaning that sulfur vulcanization is not p s ible an

othe cur sy st em ty esar ne ded

Cur sy st ems b sed on zinc an ma nesium o ides ar the efor used t o efe tively c os lnk

p lychloro r ne rub e an chlorosulfonat ed p lyethy lene rub e s

4.5.5 Other vulcanizing systems

The e ar several othe vulcanization sy st ems bey nd the ones alr ady desc ibed, w hich t en t o be

used t o vulcaniz some of the lowe v lume rub e ty es These inclu e p lyfu ctional amines w hich

can be used t o c os l n p lychloro r ne homo olyme , poly c y lat e rub e s, epichlorohydrin rub e s

an some fluorocarb n rub e s In ad ition, q inone dio ime an phenol c r sin cur sy st ems ar also

used t o vulcaniz spe ific ty es of buty l rub e

4.6 Efect of elevated temperatur e on rubbery pol ymer s and r ubber additi ves

Due t o their chemical complexity, the e ar a larg e n mbe of r actions an int eractions that do oc ur,

an ha e the p t ential t o oc ur, w hen rub e comp u ds ar subje t ed t o high t empe atur s These

elev t ed t empe atur s afe t a wide rang e of ingr dient an component within rub e comp u ds,

inclu ing:

a) base polyme an chemical spe ies within rub e compoun s such as p lyme ization aids an

r sid al monome s;

b) r active, functional ad itives such as antio idant an othe ad itives w hich ar r active an pla

a role in vulcanization, e.g ac ele at ors an co-ag ent ;

c) low mole ular weight ad itives an low mole ular weight fractions within multi-comp nent

additives such as oi s

When a rub e is heat ed, the e ar seve al me hanisms an rout es that g ene at e low mole ular weight

comp u ds that ha e the p t ential t o contribut e t o rub e fumes Some of these involve degradation

r actions an othe s inv lve such things as s a i zation r actions an r actions as ociat ed with the

vulcanization of the rub e

5 Definition of rubber fumes

The def inition of rub e fumes was es a l shed b ISO/TC 45 as “a v riet y o s ubs ta c es emit ed from

ru be c omp u ds into a workplac e atmos phe e as a r s ult o indus trial proc es s in , the c omp s itio o

which depends o the frmulatio o the c omp u ds c onc erned, the proc es s techn lo y in us e a d the

as s oc iated proc es s p ramete s.”

[94]

The a o e def inition was b sed on the definition given b the UK Health an Safety Ex ecutive (HSE) in

it EH40 publcation an the Method for Det ermination of Hazardous Subs anc (MDHS) Numbe 47,

w hich ha e be n in use in the UK rub e in us ry for a n mbe of years The HSE def inition is as folow s

“ R ub e fumes ar evolved in the mixing, mi lng an blen ing of natural rub e an rub e or synthetic

elast ome s, or of natural rub e an synthetic p lyme s combined with chemicals, an in the proc s es

w hich conve t the r sultant blen s int o f inished prod ct or p rt the eof, an inclu ing any inspe tion

proc d r s w he e fumes contin es t o be evolved”

In ad ition t o high-t empe atur vulcanization proc s es w he e chemical c os lnking r actions

oc ur ed an prod c d low mole ular weight r action b -prod ct , the HSE definition also inclu ed

o e ations that we e con uct ed at lowe t empe atur s, but w hich can r sult in the volati ization of

cons ituent within the rub e

The HSE definition ad r s es the v rious situations in w hich rub e fumes can be g ene at ed, but does

not ad r s it composition The efor , t o pro ide a mor complet e definition of rub e fumes, this

comp sitional element has also be n taken int o ac ount From consulting a uthoritative s u ies an

information sour es, it eme g es that any conside ation of the chemical natur an comp sition of

rub e fumes should inclu e the folowing clas es of spe ies:

a) g ses, e.g carb n disulfide;

b) v p urs, e.g volati e lq ids such as t oluene;

c) ae osols, e.g hydrocarbon oi an plas iciz rs;

d) spe ial case compoun s, e.g N-nitrosamines, aromatic amines an p ly romatic hydrocarb ns

(PAHs)

Conside ing al of these clas es of comp u d ensur s that a compr hensiveev luation of the comp sition

an natur of rub e fumes is un e taken, with no spe ies being o e lo ked or disr g rded In g ene al,

rub e fumes can be conside ed as being comprised of b th “visible” an “invisible” fractions The g ses

an v p urs in the l s a o e make up w hat can be r g rded as the “invisible” comp nent of rub e

fumes, with the ae osols forming the “visible” comp nent

The 1 74/ 5 BRMA/Ra ra environmental survey r p rt ed that he solvent-soluble portion of airb rne

p rticulat es pro ides an efe tive measur of “visible”fumes from hot rub e The MDHS Method 47 for

the det ermination of rub e fumes an rub e d s , w hich has alr ady be n r fe r d t o a o e, uses the

cyclohex ne-soluble fraction of the airb rne contamination cole t ed on a glas f ibr f ilt er as being the

rub e fumes portion, with the insolublefraction being r g rded as the rub e d s fraction

To o tain analytical data on the “invisible” ( i.e g ses an v p urs) fraction of rub e fumes, several

a pro ches have be n used b scientis s o e the years A p pular method inv lves tra ping the

comp u ds (ISO/TS 1 7 6) an then using a chromat ogra hic t echniq e (e.g GC-MS) t o sep rat e an

identify the v rious comp un s that ha e be n tra ped In some cases, spe ial z d eq ipment has

be n man factur d that closely mimics the curing proc s es used in the in us ry (e.g compr s ion

moulding) and is int erfac d with the analytical eq ipment in such a wa that it transp rt the fumes

dir ctly int o it, th s a oiding, as far as p s ible, any los es that ma take plac w hen an int ermediat e

“ ra ping” s ag e is emplo ed

Finaly, for the b sis of this s u y, this multi-comp nent (or clas ) definition of rub e fumes desc ibed

in the a ove p ra ra hs is being used as a means of ev luating the exis ing l t eratur an it is not

ne es ari y being pro osed as a futur means for def ining rub e fumes

6 Nature and c omposition ofr ubber fumes

Based on the r sult of the l t eratur sear h, this clause pro ides a summary of the natur an

comp sition of rub e fumes with r g rd t o the v riety of chemical comp u ds that can be pr sent,

their origins, the dife ent phy sical forms in w hich they can exis within the fact ory environment

( i.e g ses, ae osols, et c ), and the chaleng es that ha e t o be met in orde t o tra an analy se rub e

fumes efe tively Furthe information on the r fe enc scit ed in this clause is pro ided in Clause 8

As shown in 6.4, the e ha e be n many chang es in rub e t ech olo y o e the p s 40years in r sp nse

t o an inc easing awar nes in the ne d t o prot ect the health of worke s an these mean that the

comp sition of rub e fumeshas also chang ed o e this pe iod

6.2 Key c omponents of rubber fumes and their or ig in

The work that has be n car ied out t o charact eriz rub e fumes has shown that it comprises a wide

rang e of chemical spe ies with r spe t t o mole ular weight an comp u d ty e ( i.e p larity an

s ructur ) S ve al s u ies ha er port ed o e 3 dife ent spe ies in the fumes from a p rticular rub e

comp u d, an the ext ensive work car ied out b Ra ra Te hnolo y, an othe org nizations such as

Tr leb rg In us ri AB, Aspen R esear h an the Ge man Ins itut e for R ub e Te hnolo y, ha e shown

that o e 1 0dife ent chemical spe ies could be det ect ed in the fumes g ene at ed b the vulcanization

of 40 dife ent compou ds using a “ po l” of 7 comp un ing ingr dient

W ith r spe t t o the rang e of chemical spe ies ty es pr sent in rub e fumes, seve al scientis s ha e

identified that a larg e rang e of chemical spe ies ar pr sent, with the folowing ty es being r pr sent ed:

a) alphatic hydrocarb ns — s raight chain an cyclc;

b) aromatic hydrocarb ns;

c) halog enat ed comp u ds;

d) isothiocy nat es;

e) ket ones;

The r lative contribution of these t o any given sample of rub e fumes ar depen ent on the ingr dient

pr sent in each rub e comp un contributing t o the fumes pr sent in the working atmosphe e at a

p rticular moment in time

This wide rang e of spe iesin rub e proc s fumes is pr sent in many phy sical forms, e.g g ses, v p urs

an ae osols The r lative levels ofthese dife ent phy sical forms v ry ac ording t o the dife ent ar as

(e.g mixing, moulding, st orag e, et c ) within the rub e fact ory ( e Clause 7) The e ar thr e dis inct

sour es of v lati e comp u ds that wi l be pr sent in rub e fumes:

— volatie ingr dient , e.g antio idant an plas iciz rs;

— volatie impurities in ingr dient , e.g r sid al monome san man facturing impurities;

— volatie r action an br akdown prod ct of chemical r actions that oc ur d ring proc s ing,

e.g vulcanization an anti-o idant activity

6.3 Trapping and anal ysis of rubber fumes

6.3.1 General

S ve al methodsand t ech iq es ha e be n used for the tra ping an analysis of rub e fumes Bearing

the comp sitional complexity desc ibed in 6.1 in min , these methods an t ech iq es have be n

designed t o achieve the mos ac urat e charact erization p s ible

The work that has be n car ied out fal s bro dly int o two dife ent cat eg ories: that w hich has be n

done within fact ory environment an that w hich has be n car ied out un e la orat ory con itions A

summary of the work car ied out in the two dife ent ar as is shown in the subseq ent ubcla uses

6.3.2 C aracterizatio stu ies car r ied o t in factor y environments

The Health an Safety Ex ecutive publshed MDHS Method 47 2 for the det ermination of rub e d s

an fumesin rub e fact ories in 1 8 an publ shed a r vised ve sion in 1 9

[72]

This is the s an ard

method used in the UK an the methods used in seve al othe countries ar b sed on it Howeve ,

this method can encou t er diff iculties w hen it is used in situations w he e the e is cyclohex ne

soluble org nic d s , an cyclohex ne soluble rub e chemicals, such as st earic acid, b th r sulting

in an o e es imation of the amount of rub e fumes pr sent Also, an analy sis of the rub e d s

an fumes data on the E ro ean Union Conc rt ed A ction pro ramme data ase has shown that using

polyt etrafluoroethy lene (PTFE) f ilt ers, rathe than glas fibr f ilt ers r commen ed b MDHS 47 2, can

influenc the r sult o tained

Anothe a pro ch taken in r sp nse t o the complexity of rub e fumes is t o car y out mathematical

model ng of the emis ions, p rticularly t o as is in the design of in us rial eq ipment for the

cole tion of fumes An ex mple w he e this has be n used is t o profile the emis ions from the o ening

of compr s ion moulds in the man factur of tyr s w he e one es imat e put the n mbe of pos ible

chemical comp un s at up t o 40 Onc these models ha e be n develo ed, ex e imental data has be n

o tained on the actual fumes t o che k on the ac uracy of the pr dictions

The visible fraction of rub e fumes, the ae osols fraction, is beleved t o be formed at wo s ag es in the

prod ction proc s :the mixing s ag e (d et o the larg e me hanical s r s es an local o e heating within

the rub e comp un ) an the vulcanization s ag e (d e t o the condensation of v p urs of high b i ng

p int subs anc s) In b th cases, the ae osol particles contain n me ous subs anc s ca tur d b the

oi-l ke mat erial forming the ae osol Data w hich has be n o tained on the ae osol that was as ociat ed

with the vulcanization fumes from a p rticular nitrie rub e compoun has shown it t o be mainly

comprised ( 90 % ) of plas iciz rs within the compou d

In orde t o tra , identify an q antify as many component of rub e fumes aspos ible, it is ne es ary

t o design an use multifac t ed sampl ng an analysis methodolo ies Ta le 3 gives an ex mple of such

a sy st em, w hich has be n v ldat ed for a t otal of a pro imat ely 5 single chemical subs anc s

[5 ][56]

Table 3 — Detai s of a multifaceted sampl ng and analy sis sy stem for rubber fumes

Highly volatile alip atic an aromatic compou ds A ctivat ed char o l GC or GC-MS

Highly volatile chlorinated compou ds A ctivat ed char o l GC-E D

Carb n disulf ide an highly volatile sulfur compou ds S mpling b g GC-F D

ISO/TS 1 7 6 spe if ies a q altative method of TD-GC-MS for the identification of v lati e component

in rub e fumes, aft er tra ping on a sold sorbent b sed on 2,6-dipheny lpheny lene o ide p lyme r sin

It is a plca le t o a sc e ning of emis ions from the proc s ing ofrub e comp u ds in the ambient

workplac an st orag e environment It a plcation ena les spe if ic compoun s in rub e fumes t o be

identified an alow s the p t ential t o as es the contribution of c rtain comp u ding ingr dient t o

the fumes By identifying subs anc s, it also pro ides charact erization data that the HSE 47 2 method,

being a solely cumulative q antitative method, does not Howeve , it has lmitations, w hich inclu es

the fact that it only identif ies subs anc s an does not q antify them an that the data o tained wi l

be influenc d b the inhe ent spe if icity of the sorbent used for the tra ping s ag e F or ex mple, the

sorbent used in this method wi not be ca a le of efficiently tra ping an r taining al of the ty es

of subs anc s lst ed in Ta le 3 Data g ene at ed using this ISO method has be n publshed

[7 4]

an is

r prod c d in 8.1.2

6.3.3 C aracter izatio stu ies carr ied o t u der laboratory c onditio s

In some cases, la orat ory-b sed sy st ems ha e be n designed an as embled for the g ene ation an

charact erization of rub e fumes One of the mos ext ensive ex mples of these was the pro ramme

of work car ied out b Ra ra Te h olo y from the lat e 1 7 s u ti the lat e 1 8 s In this work, a g s

trans e mould w hich was ca a le of mimicking a compr s ion moulding proc s was dir ctly int erfac d

t o a GC-MS This ensur d that r pr sentative fumessamples we e g ene at ed an then trans e r d int o

the analytical ins rument q ickly an with negl gible los as no int ermediat e tra ping s ag e (w hich can

introd c biases)was inv lved A larg e n mbe of ex e iment using dife ent rub e comp un s we e

pe formed using this set up an the data o tained on the rub e fumes that was g ene at ed, with o e

1 0 dife ent spe ies being identif ied, ena led a n mbe of important ingr dient/ roc s con ition

r lationships t o be es a l shed

A la orat ory-b sed sy st em for s u ying the comp sition of rub e fumes, simiar t o the one set up b

Ra ra Te h olo y, was implement ed b worke s at Aspen R esear h This consist ed of a moulding pr s

coupled t o a GC-MS, and ena led a ra id sc e ning of v rious rub e formulations for the identification

an q antification of org nic comp u ds pr sent in their vulcanization fumes The r sult r p rt ed

we e from nine dife ent vulcanizat es ty icaly used in the in us ry ( SBR-, NR-, NBR-, CR- an E

DM-b sed comp u ds) The efe t of curing time an pr s ur we e inves ig t ed, aswel as r cipe chang es

within a given comp u d se ies

Othe a pro ches t o charact eriz rub e fumes in the la orat ory ha e involved the g ene ation of fumes

b heat ed r act or c ls, cur simulation a p ratus that ena les contin ous samplng of the ev lved

fumes t o take plac , an headsp c GC-MS t ech iq es These methods se k t o analy se the fumes as

dir ctly as pos ible without the ne d t o trap/cole t it using an int ermediat e s ag e and ha e made

v lua le contributions t o theun e s an ing of it natur an complexity

6.4 Chang es in rubber technolog y that have influenc ed the nature and c omposition of

r ubber fumes and improved the pr otection of wor ker in the industr y

6.4.1 General

The e ha e be n a n mbe of chang es in rub e t echnolo y o e the years (e.g the mo e t o low or

nitrosamine fr e ac ele at ors, and the r d ction in PAHs in proc s oi s) that had an imp ct on the

comp sition of rub e fumes an ha e r sult ed in impro ement in the prot ection of workers in the

rub e in us ry, r d cing thelevel of ex osur t o rub e fumes in g ene al

Some of these chang es ha e be n brought in slow ly o e many years, an below is a brief summary

of the main ex mples that ha e be n r vealed b the l t eratur sear h, w hich is pro ided in ful, with

ad itional information on the r fe enc s cit ed in Clause 8

6.4.2 Overal tr end in rubbe wor ker ’ e x posure to total rub e fumes

An analy sis of the rub e d s an fumes data on the Euro ean Union Conc rt ed A ction pro ramme

data ase

[1 ]

has shown that the level of ex osur t o t otal rub e fumes has de l ned b arou d 4 %

pe year from the mid-1 7 s t o 2 0 This r d ction is beleved t o be d e t o seve al fact ors, such as

impro ement in the design of ventiation an extraction sy st ems, chang es in working practic s an

chang es in t ech olo y such as using int ermix ersinst ead of o en-mi l mixing

6.4.3 Pol yaromatic hydrocar bo s

Poly aromatic hydrocar bons (PAHs) ha e be n the focus of attention for many years, with scientis s

commenting on their pr senc in rub e prod ct (d e to the use ofhydrocar bon proc s oi s) an

henc , rub e fumes in the 1 7 s The situation r mained r asona ly cons ant u ti the late 1 9 s when

environmental conc rns as ociated with their pr senc in tyr rub e dep sited on ro ds in S an ina ian

cou tries, e.g Sweden, led t o the develo ment of low-PAH content exten e ois for use in tyr s

6.4.4 Nitrosamines

The pr senc of nitrosamines in rub e comp u ds an rub e fumes has also be n r co niz d for

many years One of the main drive s that brought a out a chang e in the rub e t echnolo y used in the EU

was the is uing in the mid-1 80s b Ge man authorities of s ring ent new guidelnes on N-nitrosamine

cont ent in fact ory atmosphe es To ad r s these low lmit , new ac ele at ors for the curing of rub e

we e develo ed, w hich eithe ha e se ondary amine br akdown prod ct that ar les l kely t o form

nitrosamines or wi l not form any nitrosata le br akdown prod ct at al

6.4.5 Siane c ou l n ag ents and resorcinol ste l c ord c oating ag ent

Two othe ex mples, b th in the tyr in us ry, w he e the influenc of spe if ic ad itives on the

comp sition of rub e fumes has be n ad r s ed o e the p s 2 years ar si ane coupl ng ag ent

(w hich l be at e ethanol d ring use) an r sor inol st eel cord b n ing ag ent In the f irs case, new

low v latie cont ent coupl ng ag ent have be n develo ed an , in the case of r sor inol, the use of

pr dispe sed r sor inol t o r d c fumes an odour has be n inves ig t ed

7 Factors afecting the variabi ity ofr ubber fumes

As with Clause 6 w hich is b sed on the r sult of the lt eratur sear h, this clause pro idesan o e view

of the principal fact ors that afe t the v ria i ity of rub e fumes Furthe information on the r fe enc s

cit ed in this cla use is pro ided in Clause 8

7.2 Influenc e of the rubber c ompound formulation on the c omposition of r ubber fumes

Many workers ha e demons rat ed that the chemical spe ies that ar in rub e fumes dir ctly r lat e t o

the ingr dient pr sent in a rub e comp u d

An ex mple of the publshed data

[3 ]

that i lus rat es this is shown in Ta le 4 In this ta le, dife ent

comp u ds that ar b sic in charact er that ha e be n det ect ed in the fumes emitt ed from fivedife ent

ty es of rub e ar lst ed

Table 4 — Basic compo nds detected in the fumes from five diferent rub er

R ub e ty e Fraction of fumes C mp u ds identified

SBR Basic Aniline, ac idine or b nzoq inoline,p thalimide,

dicyclohe ylamine, 2-(4-morp oliny l)b nzothiazole, 6 PD

E DM Basic Morp oline, N-cyclohe y l formamide, cyclohe ylamine,

N-butyl 1-butanamide,di so utyl p thalat e,

2-cyclohe yl b nzothiazole

NBR Basic Dimeth l-2-butanamine, 3-(diethy lamino) propane nitrile,

nicotine, tetra uty l ure , p thalates, aniline,

B ty l Basic Benzidine, N-(2,2-dimeth lpropy l) N-meth l b nzenamine,

N-ethy l-2-b nzothiazolamine, b nzothiazole,

p eny l b nzimidazole

SBR /NR Basic N-cyclohe y lmethanamide, cyclohe yl isothiocyanate,

chloro lkanes, p thalates, aniline, nicotine

NO E 1 The nic tine in the ls s above c uld have be n d e to operatives smokin whie the fumes were bein c le ted

NO E 2 In some c ses, spe ies that w ould not be e pe ted to be present in the ru ber fumes of the par icular c mpou d

bein s u ied are repor ed (e.g p thalate f om an E DM) This c uld be d e to pro es fumes fom other ru ber bein

pro es ed ne rb , e.g a Nit ie ru ber in the E DM c se

NO E 3 The terms “Fra tion of fumes” an “Basic” relate to the fa t hat he fumes c le ted was separated into f ive

separate f a tions: basic, a idic, polar neut al, alp atic an aromatic Only the data obtained on the “Basic” fa tion is

shown in this table

7.3 Influenc e of difer ent manufacturing proc es es on r ubber fumes

In ad ition t o the comp sition of rub e , two othe fact ors that have a larg e influenc on rub e

fumes ar the particular man facturing proc s (e.g moulding, extru ing, calen e ing, et c ) an the

proc s ing t empe atur , w hich wi l be discus ed in this subclause an subseq ent subclauses

It has alr ady be n mentioned in 6.1 that the ty e of proc s emplo ed in a rub e fact ory can afe t

the natur of rub e fumes, with ae osols mainly being formed in the mixing an vulcanization s ag es

In thecase of the othe fraction, the “invisible” (g ses an v p urs)fraction, although some ar pr sent

in mixing fumes an in the st or s w he e f inished rub e prod ct ar kept, the gr at es conc ntration

is pr sent in vulcanization fumes

Taking int o ac ount t otal fumes ( i.e b th visible an invisible fractions) within a p rticular rub e

fact ory, the o e al levels of fumes v ry ac ording t o the ty e of proc s being car ied out, i.e mixing,

extru ing, moulding, st orag e, et c F or ex mple, in the g ene al rub e g oods (GRG) se t or, the o e al

level of ex osur t o rub e fumes has be n fou d t o v ry as shown below:

Moulding >Extrusion > Mi ing

These dife enc s r lat e t o fact ors such as t empe atur an the amou t of surfac ar a ex osed t o the

atmosphe e

An ex mple of the fumes data that has be n o tained on the v latie org nic subs anc s (V S) in

dife ent ar as of a tyr man facturing sit e isshown in Ta le 5

[17]

Table 5 — Volatie org nic substances detected in diferent are s of a tyre man facturing site

Prod ction ar a Spe ific ar a

Numbe of

identified V S

Total cont ent of VOS

(mg m3

V S = Volatie organic su s anc s

7.4 Influenc e of diferent pr oc es ing temperatures on the c omposition of rubber fumes

Work car ied out b W il oughb

[1]

using the Ra ra GTM/GC-MS combination with an SBR comp un ,

i lus rat ed how the proc s ing t empe atur can afe t the ty es an levelsof hydrocarb n spe ies that

ar det ecta le in it fumes This data is shown in Ta le 6

Table 6 — Efect of vulcanizatio temperature on levels of particula h drocarbo compounds

in fumes from an SBR compo nd

Vulcanization 1

(at 1 5 °C t o 1 5 °C)

µg m3

Vulcanization 2

(at 1 0 °C t o 2 0 °C)

µg m3

As shown in Ta le 6, the situation is complcat ed, with the levels of some comp un s r d cing and

othe s inc easing asthe vulcanization t empe atur isinc eased

Ra ra also r port ed

[2]

on the efe t that changing the moulding t empe atur has on the amou t ofa

particular r action prod ct ( in this case, carbon disulfide) r leased from a sulfur cur d EPDM rub e

containing the ac ele at or TMTD Inc easing the t empe atur in st eps from 1 0 °C t o 2 0 °C an finaly

2 0 °C, inc eased the amount of carb n disulfide r leased from 1,0 m.mole, t o 1, 91 m.mole, an finaly

t o 2,34 m.mol This work b Ra ra also demons rat ed that b modifying the cur sy st em, no carb n

disulf ide is lbe at ed

Anothe r p rt ed ex mple

[3]

of the efe t of proc s t empe atur inv lves the amou t of TDI

lbe at ed from a ur thane ad uct curing ag ent for NR comp u ds The amount of fr e TDI foun in

the vulcanization fumes was foun t o r d c as the t empe atur was r d c d from 2 0 °C t o 1 3 °C

Dife ent levels of fr e TDI we e also foun for the same comp u d a o e a mixing mi an a o e a

moulding pr s , showing the efe t that dife ent proc s es an proc s ing con itions can have

Finaly, anothe Ra ra p pe showed how the t otal amount of rub e fumes, det ermined as t otal

weight los , v ries with vulcanization t empe atur As ex e t ed, the t otal amount of fumes was fou d

t o inc ease as t empe atur rises, as shown below:

In this subclause, the r sult that ha e be n o tained on the comp sition an natur ofrub e fumes b

car ying out a compr hensive lt eratur sear h ar r port ed

The majority of the articles ar taken from journals chosen ac ording t o t echnical me it, subje t matt er

( i.e p lyme s an p lyme r lat ed) an ar pe r r viewed

8.1.2 Rubber fumes data o tained fr om factor y atmospher es

Frolkov , et al

[17]

r p rt ed w he e levels of v rious t oxic subs anc s in the air in dife ent dep rtment

of a tyr fact ory wer comp r d an t oxic subs anc r leased from s yr ne-butadiene rub e s,

polyiso r ne, carb n black, vulcanizing ag ent an proc s oi s we e lst ed

F or ex mple, some of the spe ies foun t o be r leased from a butadiene-s yr ne p lyme used in tyr

man facturing ( SKMS-3 ARK) an heat ed t o 1 0 °C (a ty ical vulcanization t empe atur ) we e the

— alpha-methy l s yr ne

In ad ition t o working dir ctly with tyr ingr dient , monit oring work in v rious working ar as within

a tyr fact ory was u de taken t o det ermine the n mbe an t otal level of v lati e org nic subs anc s

(VOS) that we e pr sent The r sult o tained show that VOS in dife ent prod ction ar as dife

conside a ly, as shown in Ta le 7

Table 7 — Variation in levels of v lati e org nic su stances fo nd in diferent are s of a tyre

)

Prod ction ar a Spe ific ar a

Numbe of

identified V S

Total cont ent of VOS

(mg m3

The pro lems on t oxic chemical r lease an car inog en ex osur d ring the man factur of tyr s ar

also conside ed an discus ed in this r fe enc Particular att ention is given t o the q alties and ty es

of p ly romatic hydrocarb ns (PAHs) pr sent in dife ent ty es of carb n blacks an aromatic proc s

ois The q antity of one of the principal PAH compoun s, benz(a)pyr ne, was det ermined in the working

environment in four ar as of a fact ory, the carb n black st or house, the mixing department, the mixing

ar a an d ring transp rtation an mixing The conc ntrations fou d v ried betwe n 0 mg m

3

an

0,45mg m

3

, with the highes levels det ect ed in the carb n black st or house

The levels of N-nitrosamines formed b ac ele at ors such as MBS, OTTBS an TMTD wer det ermined

in vulcanization fumes an r maining in the vulcanizat e aft er curing, with the levels shown t o v ry

betwe n 0,1 µg/ m

3

t o 9,1 µg m

3

in fumes an 1 µg kg t o 48 µg kg in the vulcanizat es The t otal

levels of N-nitrosamines pr sent in the working atmosphe e of dife ent ar as within the fact ory we e

also es a lshed Levels betwe n 2,1 µg m

(f inished prod ct st or house) we e fou d

W ith r spe t t o rub e d s , the ex osur s in the mixing an mi lng ar as of tyr works in R us ia we e

comp r d with those foun in the Unit ed King dom The v lues r p rt ed for the UK wer shown t o be

lowe in b th cases These workers conclu ed that the main causes of ambient air p lution at yr plant

we e v lati e org nic subs anc s, PAHs, N-nitrosamines an d s W ith r spe t t o the contribution of

VOS, the comp sition of this comp nent depen s up n the formulation of the rub e comp u d, an the

the mal an the mome hanical con itions of a p rticular proc s This p pe was original y publshed

in R us ian in the journal Kauch k i R ezina

[18]

an this ve sion is an Engl sh translation

A group of in us ry spe ial s s, on behalf of the EU-EXASRUB consortium, ha e used the rub e d s

an rub e fumes data pr sent on the E ro ean Union C nc rt ed A ction t o es a l sh ex osur tr n s

in the EU rub e in us ry between the 1 7 s an 2 0

[1 ]

The fumes an d s data pr sent in this

data asehas originat ed mainly from complanc t es ing, but also d e t o event such asthe ev luation of

emis ion controls an a p rt of r sear h proje t This p pe desc ibes the detaied an compr hensive

s atis ical model ng an analy sis that was car ied out and the r sult that we e o tained One of the

o e al conclusions was that the a e ag e level of ex osur t o rub e d s an it cyclohex ne soluble

fraction ( i.e rub e fumes) ha e de lned, on a e ag e, b 4,3 % an 3,3 % (r spe tively) pe year from

the mid-1 7 st o 2 0 This s u y also in icat ed that dife enc s in sampl ng methodolo y, for ex mple,

the use of eithe glas fibr or p lyt etrafluoroethy lene (PTFE) f ilt ers, can influenc the r sult o tained

Anothe publcation r lat ed t o the EU EXASRUB proje t has be n publ shed in the Annals of

Oc up tional Hy giene,

[2 ]

w hich co e s the c eation of a data ase manag ement y st em for information

on oc upational hy giene measur ment that could be used t o develo ex osur models in the Euro ean

rub e man facturing in us ry In a 6-month pe iod, 5 60 measur ment from 5 3 survey s in

3 3 fact ories from 1 5 to 2 0 wer r corded The data ase consist ed primariy of measur ment

of N-nitrosamines, rub e d s , solvent and rub e fumes The coding of epidemiolo icaly r lev nt

information was done consist ently with int er-c ntr ka p s atis ics betwe n 0,8 an 1,00 F or

oc up tional hy giene information, v lues of ka p s atis ics we e es imat ed t o be betwe n 0,6 an

1,0 Analyses showed that coding of epidemiolo ical y r lev nt information in such a multic ntr ,

multi-cou try s u y was consist ent Howeve , larg er e rors oc ur ed in the coding of oc up tional

hy giene information, an this was primariy caused b lack of information in the primary r cords of the

measur ment

Vlaso , et al of Amt el-Che noz me publshed an article

[2 ]

w he e mathematical modelswe e desc ibed

t o pro ide a b sis for the develo ment of an engine ring proc d r in the design of in us rial

eq ipment for the cole tion of g s emis ions prod c d d ring the vulcanization proc s es in the tyr

in us ry, p rticularly d ring the o ening of compr s ion moulds at he en of the vulcanization pe iod

Table 7 (c ontin ed)