p.1 

OAR Box 1413 

Prepped by Ollie Stewart 

Document Number: 

75) 11-1-76 

Docket Number: 

A-94-52 

Printed 7/9/2008 3:11:23 PM Sheet 75 of 114 
•-B W S?-;

: Ti How Low is 

"Low Styrene" Resin? 

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ow, that is a loaded question if ever there was one. As the composites 

moves forward into the next century, the answer to this ouestion is going tc become 3 

more and more important. 

industry;! 

Many regulators still do not fully understand the mfferen^fi^jffi&n an un ;aturated i 

polyester resin and a paint or coating. To many of them, the styrene in a resin is no different than the lacquer thinner in an automotive coating. This means that there may continue j 

to be regulators who take the overly simplistic view that sources can simply choose low J 

I styrene resin systems at any time, and for any application. 

This belief in die past has led to some stardingly inappropriate pennit conditions.: 

•'28-i ~&\. There have been reports of facilities that were required to use 18% styrene content systems, M 

f- It turned out to be a revelation to everyone involved that these resins simply did not exist. | 

f|t There are still companies with permit limitations on styrene content rhat are unrealistic,1 

and unworkable. 

Many of these facilities have resorted to rhe use of inert fillers to "lower" the styrene $j 

content ofthe resin until rhey reach rhe 30%, or 33% styrene content "by weight" required 

in their permit. 

This is an approach that has been bolstered by the South Coast Air Quality 

Management Distria's Rule 1162. This regulation contained language that required the 

use of resins with 35% styrene content by weight "as applied". The "as applied" equated 

inert fillers with the polyester solids content of the resins. 

Some would argue that it is probably less important that a system be a "low styrene" 

system than it be demonstrated to be a low styrene emitting system. 

By Steve McNally 

Composites Fabricators Association 

Composites Fabricationl)unt 1998 
P.3 

The question remains, is this highly 

ed system a low styrene resin system, 

e answer is, no! Not in any meaningsense. 

The emissions testing which was 

formed by the CFA over the past few 

rs has indicated that inert fillers have 

tiimal impact on the emissions from a 

ticular resin system. The testing 

licates that taking a 45% styrene 

cem and adding filler until it reaches 

Vo styrene content by weight does not 

duce a low styrene emitting system 

ich is similar to a 35% styrene content 

t resin. 

One of the unique aspects of 

niposites manufacture is the way the 

ustry answers simple questions. 

Question: 

How strong is a composite?" 

Answer: 

What do you want it to do?" 

Unlike many metals, composites 

:erials do not necessarily have 

ineering tables which outline the 

sical properties of the material, and so 

e are many variables to be considered 

nyone tries to figure out how strong 

stuff is. 

The reason that this is important in 

context of this article is that strength, 

tg with certain other important physiproperties, are imparted as a function 

ie resin chemistry. 

Based on what anyone might strive to 

eve'in a finished product, there is a 

t variety of input materials which can 

aried. The various anhydrides, acids 

glycols that are used in manufacturthe base resins each impart specific 

iical properties to the "backbone" of 

resin. These physical properties affect 

final engineering properties of the 

hed composite product. 

Just as a fabricator can vary rhe type 

ber, fiber orientation, fiber content, 

fiber length, in order to affect "how 

ig this composite is", the resin 

ufacturer can modify the ratios of raw 

:rials in a resin system to achieve 

d properties. 

All of these variations impact how 

ig, or how resilient of how resistant a 

cular resin will be to certain chemical 

k. These properties are vital to the 

led composite product being useful 

icceptable in its intended application. 

An additional issue regarding the 

resin formulation is the ability of the 

manufacturer to process the resin in an 

efficient fashion. The best-finished 

product engineering properties will not 

mean a thing if the product cannot be 

produced efficiently. Poor processing will 

ensure that the product will never be 

brought to market. 

Polyester resins are complex long 

chain polymer chemicals. Located along 

Styrene has been a Volatile 

Organic Compound (VOC) 

for many years now, and to 

the extent possible, regulators 

have put pressures on 

facilities to lower their overall 

emissions of VOCs. 

the molecule are reaction sites where the 

polymer is able to crosslink with other 

molecules. 

This is where styrene comes in. 

Styrene readily with the crosslinking sites. 

Styrene forms bridges among the reaction 

sites, and thus permits the material to 

crosslink readily and at low temperatures. 

Going back a few years rhe composites industry had no restrictions on the 

amount of styrene they could load into 

the resins, which were being used. At that 

time, rhe resin manufacturers paid attention to, primarily, rhe required engineering properties of the finished product, 

and rhe process engineering demands of 

their customers. 

Over the years, regulations have 

begun to impose a slightly different point 

of view on the industry. Styrene has been 

a Volatile Organic Compound (VOC) for 

many years now, and to the extent possible, regulators have put pressures on facilities to lower their overall emissions of 

VOCs. ^ 

This was done to lower the amount 

of "tropospheric ozone" or low level 

ozone. High ozone levels are one of the 

primary components of "smog". The 

EPA measures overall air qualiry by evaluating the days a region does not exceed 

the National Ambient Air Quality 

Standard for ozone concentration. 

As one might guess, the Los Angeles 

basin has long been the home of smog. 

The Native Americans in the area had 

referred to it as the "Valley of Smoke". 

The advent of industrialization and the 

development of the Los Angeles Freeway 

system (a system of interlocking roadways 

precisely designed to produce gridlock for 

extended periods of time every day) 

helped to make the naturally poor air 

quality in the area even worse. 

The South Coast Air Quality 

Management District was given the 

almost impossible task of improving the 

air quality in the Los Angeles basin to the 

levels mandated by the US-EPA. Overall 

the task before the SCAQMD was to 

reduce VOC emissions from many different classes of sources. This was the 

motivating factor which led to the development of their Rule 1162. 

Rule 1162 was the first regulation to 

have a significant impact on emissions 

from composites facilities. This regulation targeted styrene content of the resin 

as a parameter which could be quantified, 

monitored, and enforced. 

1162 became a template for 

additional regulations in other areas of 

California, and in certain areas of other 

states. 

Forced to Change 

As industry became involved in the 

development of the MACT Standard for 

rhe composites industry, the industry was 

forced to change the way it viewed styrene 

and styrene emissions. Styrene is now a 

"hazardous air pollutant" (HAP), according to the EPA. It has been a HAP for 

some time, but only recently has this 

become important from a regulatoryperspective. As Title V of the Clean Air 

Act has been implemented, composites 

facilities across the country are viewing 

styrene as an individual pollutant. 

Not long ago, styrene was simply one 

of all ofthe VOCs emitted from a facility. 

In some areas of the country, a facility 

could emit up to 250 tons per year (tpy) 

of a combination of VOCs before it was 

considered a "major source". Under Title 
P.4 

V, new state emissions permits have to 

consider rhat 10 tons of any individual 

HAP, or 25 tons of any combination of 

HAPs make a facility a major source. 

This gets around to a ticklish area of 

the definition of a "low styrene" resin 

system. What about other components of 

a resin system? 

There are a number of resins which 

have combined monomers to show a 

lower "styrene" content. Is this a "low 

styrene" system? 

Possibly! But realistically the industry needs to look at this question very 

carefully. 

Ideal Monomer 

There are certain aspects of styrene which 

make it an ideal monomer for the industry. It is highly reactive. It is inexpensive. 

It is marvelous at dissolving the binders in 

fiberglass reinforcements. It has a fairly 

low toxicity. It works extremely well in 

room temperature and low temperature 

curing systems. 

There are some variants of styrene 

.vhich have fairly good properties in 

polyester resin applications. Alpha 

Tiethyl styrene, para methyl styrene, and 

dnyl toluene are three two of these. 

These monomers, in some respects, 

nimic styrene. They have a dear regula-

:ory benefit, in diat they are not regulated 

Tty the EPA as HAPs. Currently! 

Another monomer which substitutes 

br styrene is methyl methacrylate. This 

rhemical is a HAP, and a VOC, and it has 

;ome additional problems which need to 

)e considered, which will be addressed 

hortly. 

One problem with EPA classifica-

:ions is that they only reflect currently 

ivailable toxicity and carcinogenicity 

lata. One of the largest reasons that 

tyrene is a HAP and alpha and para 

nethyl styrene are not is because styrene 

s widely used and has been extensively 

tudied. If alpha and para methyl styrene 

vere more broadly used, they would be 

inder more scrutiny. 

There is no reason to believe that 

hese styrene substitutes would not 

>ecome HAPs if the industry were to 

>egin to use them in quantity. 

Additionally, these styrene substitutes 

lave much greater odor problems. In 

nany cases odor complaints are more ofa 

egulatory problem than anything else. 

Additionally, these monomers may are 

8 Composites Fiibrirntioiil}une 1998 

not be as reactive as styrene, which affects 

resin curing.. 

Therefore, use of alpha and para 

methyl styrene or vinyl toluene offer 

limited resolution and is not a long term 

option for achieving "low styrene" resins. 

Methyl methacrylate presents a 

different problem altogether. This 

monomer is often partially substituted for 

styrene in gel coats, and sometimes in 

resins. Methyl methacrylate is a HAP, and 

a VOC. It is more toxic than styrene in 

many respects. And it tends to emit at a 

rate significantly higher than styrene. 

Methyl methacrylate 

presents a different 

problem altogether. This 

monomer is often partially 

substituted for styrene in 

gel coats, and sometimes 

in resins. 

The EPA sponsored testing on gel 

coat emissions recently, in partnership 

with the NMMA. The results of this 

testing gave some troubling results. 

Styrene emissions from gel coating are 

approximately 50% of the available 

styrene. Emissions of methyl methacrylate in this testing were at 75% of the 

available monomer! 

This is increasingly troubling in that 

many companies are not properly considering the methyl methacrylate portion of 

their resin when making reports to the 

EPA, or when calculating emissions. 

For example, there is a "low styrene" 

gel coat on the market that contains only 

16% styrene. This material also contains 

22% methyl methacrylate! Simple arithmetic would show this to be a 38% HAP 

content system, but it really emits at a 

higher characteristic rate than a 38% 

styrene system. 

The EPA, currendy doesn't want to 

regard the differential in emissions 

between styrene and methyl methacrylate. 

Properly addressing this issue would 

gready confound the development of the 

MACT standard. 

But, that doesn't absolve the source 

from properly regarding these emissions 

within its permit, or in reporting its 

emissions in the TRI. The industry is 

currently suffering problems associated 

with using inaccurate emissions factors 

(AP-42). Improperly regarding emissions 

from methyl methacrylate will certainly 

create this same problem in the future. 

So! What is a "low styrene resin"? 

Well, it is a general purpose resin 

with less than 35% styrene content "as 

supplied" (not "as applied"). (Corrosion 

resistant resins often require much higher 

styrene contents.) 

It is a pigmented gel coat with less 

than 30% styrene content "as supplied". 

(Clear gel coats and tooling gel coats must 

contain substantially higher styrene 

contents.) 

It is not (in a meaningful sense) a 

resin or gel coat that has substituted 

methyl methacrylate for styrene on a one 

for one basis. 

It may be (for the time being) a 

material which has substituted alpha 

methyl styrene or para methyl styrene for 

styrene in order to get below 35% styrene 

for a resin and 30% styrene content for a 

gel coat. 

And the challenge still exists for 

material suppliers to do a better job 

toward reducing these numbers even 

more, ft 

Steve McNally is Directror of Government 

Affairs for the Composites Fabricators 

Association 

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