p.1 

OAR Box 1413 

Prepped by Ollie Stewart 

Document Number: 

4) 11-1-4 

Docket Number: 

A-94-52 

Printed 7/9/2008 3:11:20 PM Sheet 4 of 114 
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P.2 

A.04-62 

SOUTH COAST AIR QUALITY MANAGEMENT DISTRICT 

RULE DEVELOPMENT DIVISION 

STAFF REPORT 

PROPOSED RULE 1162-

POLYESTER RESIN OPERATIONS 

January 23, 1987 

Prepared by: Moustafa Elsherif 

Senior A.Q. Engineer 

Reviewed by: David E. Schwien 

A.Q. Engineering Manager 

Approved by: Larry M. Bowen 

Director of Rule Development 
P.3 

"I 

I. EXECUTIVE SUMMARY 

Proposed Rule 1162 - Polyester Resin Operations (PRO) is designed to 

reduce Volatile Organic Compound (VOC) emissions from production or 

rework facilities that use polyester resin. 

Polyester resin is a material uniquely capable of meeting a wide 

variety of specific process and end-product requirements. Products 

made from this material include boat or yacht hulls, storage tanks, 

automobile front ends, fishing rods, pools, spas, chairs, shower and 

tub enclosures, and panels. 

For years, the District has looked at the emissions from PRO 3s a 

nuisance, primarily because one of the reactants is styrene, a 

malodorous chemical with a very low odor threshold (0.1 ppm). 

j Neither the EPA»s Control Technique Guidelines (CTG) nor the State 

. Implementation Plan (SIP) addresses the control of VOC emissions from 

-PRO. 

Although emissions and reductions of emissions from PRO are not 

included in the Air Quality Management Plan (AQMP), staff has 

determined that the total estimated VOC emissions from PRO is 22 

tons/day. There are two main sources of VOC emissions: the first is 

the production process in which a VOC-type monomer, such as styrene 

(14 tons/day), is used; and the second is the cleaning process in which 

acetone (8 tons/day) is primarily used as a cleaning solvent. 

Staff has determined that this Rule will achieve a total VOC emission 

reduction of up to 12.6 tons/day (5.6 tons/day from the production 

process and 7 tons/day from the cleaning process). 

Staff has confirmed that compliance with this Rule may be achieved by 

either modification of tne chemical reactants or by the addition of 

film-forming additives (vapor-suppressed resins). Add-on control 

equipment such as incinerators, carbon adsorbers, or condensers are 

technically feasible but are not expected to be economically viable for 

the majority of polyester resin fabricators. According to the staff's 

cost analysis, the cost-effectiveness for these three control equipment 

techniques will vary from $19,000 to $48,000 per ton of VOC emission 

reduction. The cost of compliance through process changes or additive 

technology is expected to be minimal if material savings is considered. 

The proposed Rule includes exemptions for gel coat use and for use of 

corrosion-resistant materials (until July 1, 1990), due to the 

unavailability of low-emission technology. In addition, daily 

recordkeeping will more than likely be required for all facilities. 

II. BACKGROUND 

Currently, VOC emissions from PRO are not regulated by the District. 

Rule 442, which applies in general to the control of VOC emissions from 
P.4 

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solvent-j used in production processes, does not apply to PRO. The 

primary reason for this is the monomer (primarily styrene) used in 

these processes is considered a raw material and not a solvent. It is 

polymerized to become a part of the final cured product. 

In 1982, a report was published by the Air Resources Board (ARB) based 

on a study done by Science Application, Inc (SAI). The report 

discusses California VOC emissions from PRO and various types of 

control technology. The report recommended that the infonnation 

obtained through their survey should be incorporated into local 

emission inventories since no comprehensive detailed inventory of 

polyester resin operations existed. Also recommended was the use of 

vapor-suppressant additives and other material changes to control 

emissions. However, the report failed to address emissions from the 

use of cleaning materials. 

Currently, the Bay Area AQMD, the Shasta County APCD, and the Ventura 

County APCD have rules for PRO. None of these rules were appropriate 

for the many diverse PROs in the District. In order to develop a rule 

suitable for this area, staff held several internal workshops, two 

public workshops, many individual and group conferences, and made 

several field observations to evaluate and discuss the current 

technologies in the polyester resin industry. 

III. POLYESTER RESIN OPERATIONS 

This section briefly describes the chemistry of polyester resin, the 

industry structure, the manufacturing process, and the cleanup 

operation. 

A. Chemistry of Polyester Resin 

Polyester resin products offer a combination of properties such as: 

high strength and dimensional stability with low weight; corrosion 

resistance; excellent dielectric properties; opportunities for 

parts consolidation and design flexibility; low finish cost; and 

moderate tooling cost. 

The fabrication of polyester resin products requires a complex 

chemical reaction. A simple introduction will help explain the 

terms and the processes (please see Appendix A). 

There ?re two typoc ?f resins. The first type is general-purpose 

res::ns. An example i«> orthophthalic resins, which are used by the 

majority of the polyester resin fabricators. These orthophthalic 

resins are lower-cost resins and they satisfy im :t of the product 

specification requirements. The second type is corrosion-resistant 

resins such as halogenated, bisphenol-A, furan, vinyl ester, and 

isophthalic. These resins are relatively costly and their unique 

molecular structures allow them to resist acids, alkalies and 

solvents. 
P.5 

-3-

B. Industry Structure 

It is estimated that there are approximately 1000 firms, each with 

less than 30 employees, conducting polyester resin operations in 

the District. Most of these companies fabricate their products by 

spray-up, hand lay-up, and contact-molding types of processes. 

Approximately 50 firms, with over 30 employees each, are involved 

in automated processes such as paneling, pultrusion, or 

filament-winding. In addition to the fabricators, there are 

estimated to be about 700 rework and repair shops for automobiles, 

boats and other products. 

The total amount of polyester resin materials used throughout the 

District is approximately 128 million lbs/years (mostly 

orthophthalic). This includes 7 million lbs/year for 

corrosion-resistant applications. The amount of acetone used is 

about 600,000 gals/year. Figure 1 shows the distribution by 

product and Table 1 shows the amount of polyester resin usage 

distributed by process. 

For spray-up, hand lay-up and contact molding processes, gel coat 

is the first material to be applied to the mold and becomes the 

ultimate finish for the product. This gel coat must form a strong 

chemical bond to the fiberglass laminate. Vapor suppressant 

additives for the gel coat will make that bonding impossible. 

Also, sprayable viscosities cannot be achieved at monomer levels 

less than 35 percent. For these reasons, some provisions of this 

Rule will not apply to gel coat application. 

Fabricators that make corrosion-resistant products are concerned 

about long-term liabilities associated with their products and must 

meet rigid performance standards. Currently, the amount of 

corrosion-resistant materials used in the District is only 7 

million pounds per year. Staff believes that 3-5 years are needed 

to develop modifications of materials to meet the general 

requirements of the Rule. For these reasons, some provisions of 

this Rule will not apply to corrosion-resistant applications until 

1990. 
FIGURE 1 

Estimated Resin Used 

Distribution by Product 

40% 

Percent of Total 

30% -

20% -

10% h 

0% 

Pool/Spa Auto Tanks Marble Bath Fixt. Other Boat Panels 

Products 

H H Resin Used 

i 
P.7 

- 5 -

TABLE 1 

ESTIMATED SCAQMD POLYESTER RESIN USAGE 

(LBS PER YEAR) 

CLOSED MOLDING 

BMC, SMC, RESIN APPLIED AT PRESS, INJECTION 3,500,000 

OPEN MOLDING 

SPRAY-UP 50,000,000 

CONTINUOUS LAMINATION 2-4,000,000 

CASriNG 22,500,000 

HAND LAY-UP 15,300,000 

FILAMENT WINDING 3,400,000 

PULTRUSION 1,300,000 

OTHER 8,000,000 

TOTAL 128,000,000 
P.8 

-6-

C. Manufacturing Process 

In general, there are several production methods used in this 

industry. A survey of the PRO in the District shows that the 

simultaneous use of more than one method accounts for the vast 

majority of resin use. The following are the most common 

production methods: 

1. Spray-up 

More than half of the industry uses some form of spray 

application of resin onto a mold (see Figure 2). Fiberglass 

roving is fed into a specially designed "chopper gun" which 

chops the roving into approximately one-inch lengths; the gun 

simultaneously sprays a predetermined amount of resin and 

catalyst into the open mold; and the two chemical ingredients 

are mixed outside the gun as they exit (outside mix) or inside 

the gun (internal mix). Of all the production methods, the 

spray-up process has the highest potential for VOC emissions. 

Atomization of resin creates an enormous surface area of 

exposed resin, thus enhancing VOC loss through evaporation. 

FIGURE 2 

Spray-Up 

Mold 

Resin Catalyst 
P.9 

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2. Hand Lay-up 

This method begins with fitting chopped strands of fiberglass 

or woven fiberglass roving into an open mold, by hand. 

Catalyzed resin is then added and "wetted-out" in the 

fiberglass strands by use of rollers, brushes, or squeegees 

(see Figure 3). This method produces a higher 

strength-to-weight ratio product compared to products made 

with spray^up methods. 

A relatively large surface of resin is exposed to the 

atmosphere for most of the production cycle and helps create a 

rather high VOC emissions. 

A common practice in the industry is to combine spray-up and 

hand lay-up methods. 

FIGURE 3 

Hand LayJJp 

Roller 

Mat Impregnated 

with Resin 

Mold 
P.10 

- 8 -

3. Continuous Lamination • 

Continuous strand fiberglass rovings are chopped and evenly 

distributed onto a continuously-moving sheet of cellophane or 

other type of non-adhering plastic sheeting (see Figure 4). 

The chopped glass layer is then saturated with pre-catalyzed 

resin and covered with a second sheet of cellophane. The 

glass/resin composite sandwiched between the cellophane 

sheeting is then pulled through a forming die and passed 

through a curing oven. The emerging cured panel is then 

stripped of its cellophane covering, trimmed along the edges, 

and cut to the desired length. The VOC emission per unit 

weight of product is not high because most of the process that 

has a potential to emit VOC is contained within the top and 

bottom cellophane sheets. 

FIGURE 4 

Roving Strands 

Roving Chopper* 

' Forming 

Chamber 

Resin 

ffl Panel 

Cellophane Roll 

•Hnimitnniiin 

Resin Q 

1__ 

Panel Cutter 

P 

=3 

Cellophane Rewind 

Cellophane Roll 

_ . Section 

Trimmer 
P.11 

-9-

4. Casting or Molding 

This process is being more widely used now by companies that 

want finished components with one or two smooth surfaces (see 

Figure 5). Continuous strands are laid by hand into a mold 

and catalyzed polyester resin is poured or injected into the 

mold cavity. In some cases, the resin is mixed with 

fiberglass and other additives to form a putty or dough-like 

resin, such as the resin in a Bulk Molding Compound (BMC) or 

• i n a Sheet Molding Compound (SMC) process. This process i s " 

used for highly complex shapes and for core materials that 

require added structural strength. Most of these are closedmold processes. Emissions, in general, are low. 

FIGURE 5 

Resin Transfer 

Molding 
P.12 

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5. Pultrusion 

Continuous roving strands are pulled from a creel through a 

strand-tensioning device into a resi n bath (see Figure 6). 

When thoroughly impregnated, the formed resin/glas s composite 

i s then passed through a heated die . The finished cured 

resin/glass stock i s then cut to the desired length and 

packaged. The main VOC emission source i s the open resin 

bath, since curing (also a source o f VOC emissions) takes 

place in the enclosed die. 

FIGURE 6 

Pultrusion 

Strand Tension Device 

Pull Rollers 

Forming Die Heated Die 

Hoving Strands 

Resin Bath 

O 

Formed 

Impregnated 

Strand 

Cured, ( r \ 

Puttnided1 

Rat Stock 
P.13 

-11-

6. Filament Winding 

This method is becoming increasingly popular for the 

manufacture of large pipes, storage tanks, and other hollow 

vessels which may be subject to great internal pressure (see 

Figure 7) . Continuous strand rovings are pulled by a rotating 

mandrel through a strand tensioning device into a resin bath. 

Emerging from the resin bath, the strands, each uniformly 

coated, are wound onto a mandrel to the shape and pattern 

required for the finished product. The unit is then cured in 

an oven or at room temperature. The requirement for low-resin 

viscosity often implies the use of higher monomer 

concentration, causing a moderate VOC emission. 

FIGURE 7 

Filament Winding 

Strand Tension 

Device 

Mandrel Drive 

Rovings 

Creel 

Winding 

Mandrel 

Resin 

Bath 
P.M 

-12-

D. Cleanup Operation 

Cleanup of hands, tools, and spray guns is a very important part of 

the production cycle. Hands, brushes, rollers, and squeegees must 

1

 be cleaned with a solvent (usually acetone) after applying each 

batch of resin. Also, spray guns must be flushed with solvent 

after each use and throughly cleaned daily. This cleaning prevents 

resin from curing on the tools and in the guns, thus rendering them 

unusable. 

Cleaning solvent is usually available in 2-gallon containers for 

hand cleaning, 5-gallon containers for tool cleaning and 3- to 

5-gallon containers for spray gun cleaning. Also, most resin guns 

have a clean solvent-supply line connected directly to the gun to 

flush the internal parts after each use. 

IV. EMISSIONS 

There are generally two major sources of VOC emissions from PRO: the 

resin used in the manufacturing processes and the solvent from the 

cleanup operations during and after the manufacturing processes. 

A. Emissions From the Manufacturing Process 

VOC emissions will depend on the amount of materials used, the type 

of products made, manufacturing methods, and business activity. 

The most common monomer used is styrene. Evaporation of styrene 

from gel coat or resin during the raw material-application process 

and during the curing period is the main source of VOC emissions. 

It is estimated that up to.10 percent of the resin is lost as 

overspray or by evaporation during the raw material application 

process. In addition, up to 8 percent of the styrene monomer in 

the applied resin or gel coat evaporates before polymerization is 

complete. There are many other factors that impact the styrene 

evaporation, such as gel time, temperature, and air flow. Figures 

8, 9, and 10 show the amount of VOC emissions with each factor. 

Staff has determined that the static laboratory test methods for 

measuring VOC emissions from the polyester resin materials are the 

best and most consistent methods available. 

B. Emissions From the Cleaning Process 

Cleaning solvent emissions typically account for more than 36 

percent of the total plant VOC emissions. These emissions are due 

to the evaporation of solvent from the parts being cleaned, from 

atomization of solvent, from agitation of the solvent during the 

cleanup process, from storage of solvent in open containers, and 

from improper disposal of waste materials. 
P.15 

-13-

The number of employees applying the resin directly affects total 

solvent emissions because each employee must clean his hands, 

tools, and spray gun. 
FIGURE 8 

Influenc e of Gel Time 

gm/m£ 

Five 

on 

Styrene Emissions 

Ten Fifteen 

Minutes 

H Styrene Emissions 

Twenty 

I 
FIGURE 9 

Influence of Temperature 

on 

Styrene Emissions 

150 

Styrene Evaporation - gm/m2 

100 

25 30 35 

Ambient Temperature - "C 

I Suppressed Resin H H Standard Resin 

Ut 

I 
FIGURE 10 

200 

150 

Influenc e of Air Flow Rat e 

on 

Styrene Emissions 

Styrene Evaporation - gm/m2 

100 

at 

i 

Suppressed Resin 

Tl 

00 
P.19 

-17-

V. EMISSION CONTROL TECHNIQUES 

The three control techniques are: process changes to control monomer 

emissions, material changes for control of acetone emissions, and 

add-on control equipment. 

• A. Process Changes 

1. Modifications to Material 

Reducing the resin content can reduce the emissions. This can 

be accomplished by either redesigning the products to require 

less resin or using more fillers and colorants. Most of the 

time, however, i t is difficult to achieve the desired product 

properties by reducing the resin content. 

The conversion to low-monomer-type resins (35-weight percent) 

compared to the conventional resins (40- to 50-weight percent) 

is a viable method for the control of some of the emission 

problems previously described (see Figure 11). Several 

companies have been marketing such resins for several years. 

The cost of low-monomer resins is slightly higher than the 

cost of conventional resins. The reduction in total styrene 

emissions can reach 40 percent, by weight, when a conventional 

resin is replaced by a low-styrene resin. . 
FIGURE 11 

Influence of Styrene Content 

on 

Styrene Emissions 

120 

Styrene Evaporation - gm/m2 

32% Styrene 

Minutes 

35% Styrene -* ~ 40% Styrene

 -B _

 44% Styrene 

00 

I 

Tl 

ho 
P.21 

-19-

Another emission reduction option is to reduce the resin 

molecular weight to the point where resin, at only 35 percent 

styrene, would exhibit a low enough viscosity to readily wet 

the reinforcement materials. Unfortunately, resin with low 

monomer content might be unacceptable for the manufacture of 

some products because the resin would be more viscous and 

difficult to spray, mold, or inject (see Figure 12). Also, 

reduction in molecular weight usually is accomplished by a 

corresponding loss of desired properties (mechanical or 

physical) which also could severely limit the acceptability of 

some products. 

Recently, a modified photoinitiator polyester resin was 

developed, but i t is stil l under analysis. The new 

photoinitiator resin is a one-component resin which cures 

without additives when exposed to long-wave ultraviolet light. 

The most significant advantage of this system is the rapid 

curing (less gel time). In addition, the cure develops from 

the outside, which greatly limits styrene evaporation. 

Additional advantages are: 

o a rapid and controlled rate of cure. 

o no mixing and metering of raw materials is 

required, 

o there is minimal waste from unused resin, 

o less cleaning is needed between resin applications. 

The initia l testing of this modified resin shows a 40 percent 

reduction in emissions compared to the•emissions from the 

conventional resins. This photoinitiator additive could be 

used to produce most of the polyester resin products that are 

up to one-inch thick. 

A final option is the replacement of part or all of the 

styrene with another monomer. The search for such a monomer 

has been the subject of research by many companies for some 

time. The ideal material, of course, is a monomer with all of 

the desirable qualities of styrene (good thinning capacity, 

good mechanical properties, and ease of polymerzation); and 

one which is a low-VOC emitter, and is cost-effective as a 

styrene substitute. 

2. Suppressed Resins 

The most promising technology today for reducing VDC emissions 

is the use of suppressed resins. These resins decrees* VOC 

emissions by entrapping some of the monomer that would 

otherwise vaporize during the exothermic curing of the resin 

(see Figure 13)• The suppressing agent consists of paraffin 

or wax-like materials that are added to the polyester resin. 

The paraffin builds a film on the surface of the laminate 

which physically blocks the polymer surface from oxygen in the 

air and at the same time reduces styrene evaporation. 
FIGURE 12 

Viscosity vs. Percent Styrene (at 20 C) 

1600 

Viscosity CPS 

1400 

1200 

1000 

800 

600 

400 f200 

0 

0 

Hand Lay-Up 

Spray-Up 

10 

\ 

\ 

20 30 40 

Percent Styrene 

*~~ Resin 

i 

ro 

o 

i 

50 60 

ro 

ro 
FIGURE 13 

Comparison of Suppressed Resin 

and 

Standard Resin 

Styrene Evaporation - gm/m2 

20 40 60 

Time in Minutes After Laminating 

—"~ Suppressed Resin ' Standard Resin 

i 

ro 

80 

to 

co 
P.24 

-22-

Suppressed resins will reduce VOC emissions by about MO 

percent, by weight. These resins are priced slightly higher 

than the conventional resins. However, suppressed resins will 

achieve material savings which should offset the difference in 

price. Different brands of suppressed resins vary in 

performance and method of suppression. (More specific 

information is unavailable due to claims of confidentiality.) 

Presently, a few manufacturers have experienced difficulty 

with delamination, a separation between layers of applied 

resin. This happens because the suppressed resin leaves a 

thin film of wax on the surface which can be detrimental to 

the adhesion of a subsequent lamination. 

3. Closed-Mold Process 

Use of a closed-mold process is an excellent way to reduce 

styrene emissions. Some of these processes are the 

Resin-Transfer Molding (RTM) process, the Sheet-Molding 

Compound (SMC) process, and the Bulk-Molding Compound (BMC) 

process. These processes are used only for small-size 

products. 

B. Clean-up Solvent (Acetone) Emission Reductions 

Three methods to reduce acetone emissions are: correction of 

employee work habits, reclamation of spent acetone, and use of 

solvent substitutes. 

1. Correction of Employee Work Habits. 

Acetone is usually available for each employee in a 2-gallon 

container for hand cleaning, a 5-gallon container for tool 

cleaning, and a 5-gallon container for spray-gun cleaning. 

Also, most spray guns have a clean-acetone feed line to flush 

the internal parts after each use. 

Unfortunately, many fabricators' practices and work habits 

when handling and using acetone are less than ideal. Limiting 

the issuance of acetone to the employee, and proper training 

and diligent supervision with regard to the proper use and 

handling of acetone, will reduce solvent emissions. 

2. Reclamation of Spent Acetone 

There are twr options for the control of s-jtut-acetone 

emissions: on-site recovery or off-site recovery at a 

commercial solvent reclaiming facility; both offer economic 

and environmental benefits. 

Some manufacturers simply dispose of spent acetone by allowing 

i t to si t in open containers and evaporate. On-site acetone 

reclamation through the use of a distillation unit can reduce 

this loss. These units are available in different sizes in 
P.25 

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order to be compatible with the needs of various PRO. These 

units come completely assembled and can recover 90 to 97 

percent of the solvent that otherwise is lost. This approach • 

should help reduce the problems associated with the storage of 

dirty solvents. 

Some polyester resin manufacturers dispose of spent acetone at 

an off-site dump. This will contribute to VOC emissions at 

the dump site . Spent acetone can be sent to commercial 

facilitie s that specialize in reclaiming acetone as well as 

other solvents. An additional benefit of this method is that 

the polyester resin fabricator can also have the off-site 

reclamation facility dispose of solid waste included in the 

spent acetone. 

3. Use of Solvent Substitutes 

Polyester resin material manufacturers have recently developed 

low-VOC, water-based materials to replace acetone for cleaning 

hands, tools, and spray equipment. These types of materials 

are now successfully used by most of the fabricators. 

However, acetone is usually used in small quantities to dip 

tools and spray equipment for a final cleaning in order to 

remove the water from the item being cleaned. 

Work is ongoing to improve the new solvent substitute products 

and to eliminate the final use of acetone. 

C. Add-on Controls 

Four types of add-on control equipment were investigated: 

incineration, absorption, adsorption, and condensation. 

1. Incineration 

Thermal or catalytic incinerators are available to control 

emissions from spray booths, ovens and room exhausts. 

In a thermal incinerator the solvent-laden air is exposed to a 

temperature of 1000° to 1500°F and direct flame contact for a 

period of 0.3 to 0.6 seconds. In the catalytic, incinerator 

the operating temperatures are 600° to 750°F lower. In either 

case, the important incineration design factors are: waste 

gas stream flow rate , residence time, temperature, and waste 

gas heat content. Both incinerators can be designed to 

achieve 90 to 99 percent removal efficiency. However, within 

the District, incinerator;: have not, in general, been used as 

emission-control devices in the PRO. (One fabricator uses 

incineration only when the VOC emissions exceed a certain 

limit so it can comply with Regulation nil , New Source 

Review.) Incineration is most effective when the pollutant to 

be controlled is at a high concentration and has a high 

heating value. Typically, polyester resin operations have low 

VOC concentrations in their exhausts and high exhaust air 
P.26 

-24-

flows. These conditions result in low heat content exhaust 

streams, thus leading to tiigh supplemental fuel requirements 

and increasing operating costs. Therefore, incineration is 

not usually economically feasible for most PRO. 

2. Absorption 

Through the use of absorption, acetone and styrene emissions 

are removed from the exhausting contaminated air stream by 

direct contact with a liquid. The absorption takes place by a 

chemical reaction with one or more components, sodium 

hydroxide or a mixture of sodium hydroxide and sodium 

hypochlorite, in the water-based liquid. The estimated 

control efficiency is at least 70 percent. 

Absorption has not been used to control styrene and acetone 

emissions in the District. Further investigation and testing 

would have to be done to determine its applicability for the 

PRO; as a part of this, the impact of the resulting liquid and 

solid waste disposal would have to be determined. 

3. Adsorption 

Carbon adsorption is a common control technique for removing 

VOC emissions from an air stream. When the carbon reaches the 

saturation point, hot air Or steam is used to regenerate the 

adsorbent carbon. However, activated carbon can serve as a 

catalytic agent for the polymerization of some monomers. If 

high molecular weight polymers are produced, then the 

adsorbent surface can become fouled and regeneration may not 

be possible. Also, the presence of acetone emissions in the 

air stream could reduce the adsorption efficiency, since 

acetone has a relatively high heat of adsorption, thereby, 

system effectiveness is reduced when the temperature rises. 

In addition, particulate matter generated in the process can 

clog the adsorbent, thereby reducing its effectiveness and 

increasing the pressure drop through the system. 

4. Condensation 

There are two types of condensers. The first type is a 

surface condenser where exhaust air stream is cooled with a 

fluid, but does not come into direct contact with the air. 

The second type is a contact condenser where the exhaust air 

stream is sprayed with a chilled liquid. Both types are 

generally not practical because most PRO exhausts have VOC 

concentrations below 1000 ppm, and condensers work effectively 

with higher-VOC streams. 

COST ANALYSIS 

While all the emission control techniques described in this report are, 

in principle, applicable to most of the polyester resin fabricators, 

their implementation costs vary considerably. 
P.27 

-25-

The tota l capital costs listed below were based on vendor prices of the 

basic equipment and accessories. Unit electricity and natural gas cost 

were obtained from Southern California Edison Company and Southern 

.California Gas Company, respectively. 

A typical polyester resin fabricator was selected for this cost 

analysis study. Three control-equipment scenarios were evaluated. 

A. Materials Used 

Polyester Resin 

Gel Coat 

Monomer Percent (Styrene) 

Acetone 

Spent Acetone 

Manufacturing Process 

Operating Time 

Emission Factor 

B. Control Equipment 

Incineration 

Adsorption 

Absorption 

Interest Rate 

Equipment Life 

C. Operating Cost 

Labor 

Electricity 

Gas 

Maintenance, Tax & Ins. 

Styrene 

Acetone 

900 Lb/Day 

100 Lb/Day 

45% 

10 Gal/Day 

4 Gal/Day 

Combination of Spray-Up and Hand 

Lay-Up. 

8 Hr/Day, 5 Days/Wk, 52 Wks/Yr. 

Use 0.10 pound of VOC lost per pound 

of resin used. 

90% Efficiency 

70% Efficiency 

70% Efficiency 

10% 

15 Years 

$10.00 Hr 

$ 0.08 Kwh 

$ 6.47 MM Btu 

11% of Installation Capital 

$ 0.85 Lb 

$1.25 Lb 
P.28 

-26-

Based on the above assumptions, the cost-effectiveness is as follows: 

A. Control Equipment 

1. Incineration Cost 

The estimated annual operating cost is: 

Capital Cost 

Labor 

Gas 

Electricity 

50% Heat Recovery 

Credit 

Net 

$195,000 

3,000 

700,000 

12,000 

-350,000 

$560,000 

With a reduction of approximately 11.7 tons per year, the 

cost-effectiveness would be about $48,000 per/ton. 

Carbon Adsorption Cost 

The estimated annualized cost is: 

Capital Cost 

Carbon 

Labor 

Steam 

Electricit y 

Total 

$190,000 

14,000. 

2,000 

1,000 

25,000 

$232,000 

With reduction oi approximately 9.0 tons per year, the costeffectiveness would be about $26,000 per/ton. 
P.29 

-27-

3. Absorption Cost 

The estimated annual operating cost is: 

Capital Cost $150,000 

Labor 16,000 

Electricity 9,000 

$175,000 

With reduction of approximately 9.0 tons per year, the 

cost-effectiveness would be about $19,000 per/ton. 

4. Spent Acetone Reclamation Cost 

Spent Acetone Generated 8300 Gal/Year 

Cost Credit for Recycling $0.40 per gallon of acetone 

recycled 

Annual Savings $3,300 

Acetone Recovered (90% Recovery) 

Recycling yields a cost savings of about $134/Tons. In other 

words, it will pay for itself in less than one year. 

B. Good Housekeeping 

Good housekeeping and employee training are good low-price-control 

techniques for reducing VOC emissions from PRO. Staff found, 

during several field inspections, that most fabricators' practices 

and work habits are less than ideal. Most of the problems are in 

the area of resin spraying and materials handling and are readily 

correctable with proper employee training and diligent supervision. 

The use of closed containers for storing fresh and spent cleaning 

materials and waste polyester-resin materials reduces evaporation 

losses and also reduces odor problems. 

Improved housekeeping practices will result in a cost saving to the 

fabricators by the elimination of unnecessary evaporation los3. 

C. Materials Modification Costs 

The most promising materials modification methods for reducing VOC 

emissions from the polyester resin operations are: 

1. Use of low monomer polyester resin materials. 
P.30 

-28-

2. Use of vapor suppressant. 

3. Use of resins with a lower molecular weight. 

4. Use of photoinitiator polyester resins. 

5. Replacement of styrene with other low-VOC materials. 

All of the above approaches are cost-effective; however, to be sure 

that the use of such materials in some products is not accompanied 

by a corresponding loss of desired properties, additional research 

and development is required. 

VI. SIGNIFICANT IMPACTS 

A. Energy Impact 

The energy impact will be minimal. The majority of the fabricators 

will comply by reformulating materials and will not consume 

additional amounts of energy or generate additional wastes. 

B. Economic Imoact 

Small fabricators will be able to use the suppressed resin or 

low-monomer resin. Both are available and cost-effective. The 

cost impact will be minimal. 

C. Environmental Impact 

These proposed control measures will not result in any water 

pollution or in any increase in solid waste disposal. The 

reduction in emissions of reactive organics should reduce ozone 

formation in the District as well as reduce the potential for odor 

nuisance. 

D. District Impacts 

1. Enforcement 

The major impact to the Enforcement Division stems from two 

Rule requirements: clean-up and recordkeeping. The 

Enforcement Division estimates 4.5 additional inspectors will 

be needed to implement the Rule after one year. The need will 

be rediir.fi to 2 inspectors to maintain adequate enforcement 

thereafter. 

2. Source Testing 

Staff expects that approximately 20 hours per year will be 

needed for testing any new add-on control equipment. 
P.31 

-29-

3. Laboratory 

Additional laboratory samples will be required in order to 

determine compliance with the reformulation requirements. An 

estimated 200-300 hours per year will be needed to analyze 

these samples. 

4. Engineering 

Engineering Division estimates that 2.5 engineer years will be 

required to process the new applications that will result from 

the adoption of this Rule. 

VII . COMMENTS 

A. EPA; 

No comments were received from the EPA. 

B. ARB 

The ARB finds Rule 1162 acceptable and has no suggestions for 

revision. 

C. PUBLIC 

All of the public comments were channeled through the Society of 

the Plastics Industry, Inc. (SPI). 

Comment: Recommend that "Polyester Resin Operations" be changed to 

"Polyester Resin Molding Operations" to prevent confusion 

with Polyester Resin Producing Operations. 

Reply: Proposed Rule 1162 defines PRO as the fabrication or 

rework of products made from polyester resin materials. 

The proposed Rule, therefore, does not apply to the 

production of polyester resin materials. 

Comment: Change the definition of "Approved Composite System" 

since the industry refers to both resin material and 

reinforcements. In addition, change "additives" to 

"formula" in the same definition. 

R

eply: The proposed Rule was changed to "Approved Low-VOC 

Emissions Resin System." The definition applies to 

additivcc technology. Compliance by changes in 

formulation is the option described by subparagraph 

(b)(1)(A)(iv). 

Comment: Include definitions ibr gei coats ana monomers. 

Reply: The proposed Rule includes both definitions. 
P.32 

-30-

Comment: References to "closed-mold" should be changed to 

"molding." There are pultrusion processes which may not 

f it the definition of "closed-mold" but, because of 

low-VOC emission, lose less than 4 percent weight. 

Reply: Pultrusion process with less the 4 percent weight loss 

will be in compliance with the "other process 

requirement" option of subparagraph (b)(1)(A)(iv). 

Comment: Touch-up or repair should be exempt from the subparagraph 

(b)(i)(B) spraying requirements because airless equipment 

is neither practical nor available. 

Reply: If touch-up or repair of a small area is required, small 

amounts of materials may be applied with a conventional 

air-atomized spray gun. The proposed Rule will exempt 

touch-up or repair from the subparagraph (b)(1)(B) 

requirements. In our•judgment, requiring that this 

operation be done with a spray gun that has a small resin 

container attached directly to the gun—as opposed to a . 

hose connection to a large resin tank—will ensure that 

only a minimum amount of resin will be sprayed. 

Comment: Increase the small-user exemption from 50 pounds per day 

to 250 pounds per day. 

Reply: Neither industry nor the Distric t has data to support an 

exemption limit. District staff believes that materials 

modification techniques are available to everyone, and 

use of this material should have only a minimal impact on 

small users. Low-VOC resin formulations will cost almost 

the same as the conventional polyester-resin materials. 

Therefore, the proposed exemption for small users was 

removed. 

Comment: Method of analysis should be included in the Rule. 

Reply: 

Comment: 

Reply: 

comment: 

The proposed Rule references the District's "Laboratory 

Methods of Analysis for Enforcement Samples" manual which 

contains the static volatile emission test previously 

recommended by SPI. 

Solid waste such as trim should not be required to be in 

a closed container. 

Staff believes that solid waste is a source of odor and 

should be stored in a closed container. 

Corrosion-resistant materials should be permanently 

exempted from the provisions of subparagraph (b)(1)(A) 

since they constitute a small portion of the total used 

in the District. 
P.33 

-31 -

Reply: Staff believes that exemption of corrosion-resistant 

materials until March 1, 1990 should give the resin 

manufacturers time to transfer most of the existing 

conventional resin technology to the corrosion-resistant 

materials. Also, staff believes that since the need of 

corrosion-resistant materials is increasing, the amount 

of emissions will increase in the near future. 

VIII. CONCLUSIONS AND RECOMMENDATIONS 

Based on the information described above, staff concludes the 

following: 

A. Neither the District nor the SPI has detailed information on the 

total nunber of polyester resin fabricators. Staff estimates there 

are approximately 1,050 fabricators and 700 repair shops in the 

District. These fabricators and repair shops use 128 million 

pounds of polyester resin materials and 600,000 gallons of acetone 

per year. 

B. The estimated total VOC emissions from polyester resin operations 

are 22 tons/day; from the production processes, 14 tons/day; and 

from cleaning processes, 8 tons/day. The total VOC emission 

reduction is expected to be 12.6 tons/day. 

C. There have-been no emission control regulations for this industry 

because the development of technology was either incomplete or did 

not exist. Technology has improved during the last 12 months and 

is continuing to develop at a rapid pace. 

D. For the majority of this industry, the add-on control techniques 

are not technically or economically feasible. Materials 

modification or reformulation, and additives technology, are the 

most promising methods for complying with this proposed Rule. 

Staff, therefore, recommends approval of Proposed Rule 1162 for the 

control of VOC emissions from Polyester Resin Operations. 
P.34 

Appendix A 

CHEMISTRY OF POLYESTER RESIN 

Polyester resin materials have been classified as plastics. Plastics 

are various synthetic materials chemically created from organic 

(carbon-based) substances. 

There are two basic types of thermoplastics and thermosetting plastics. 

Thermoplastics are those which can be formed or shaped by heat; this 

can be done a number of times (physical change). Thermosetting 

plastics are those which, when formed or reacted, require or give off 

heat and cannot be reformed (chemical change). 

A slightly better classification than plastic s is polymers. 

Polyesters are polymers chained together in a particular order called 

ester linkages (two carbon and two oxygen atoms). 

Polyesters can be broken down into unsaturated and saturated. The term 

unsaturated refers to a chemical state in which a compound has 

chemically unsatisfied reactive groups readily available for attachment 

to other groups. In proposed Rule 1162 we deal only with unsaturated 

polyesters. The saturated polyesters are represented by alkyds 

(oil-based paints) and polyester fibers (cloth, rayon, nylon). 

There are six types of thermosetting polymer resins: isophthalic, 

orthophthalic, halogenated, bisphenol-A, furan, and vinyl ester. The 

majority of the fabricators use orthophthalic for most of their 

products. The other resins, called corrosive-resistant resins, which 

are used in applications that have acid, alkali and solvent-resistant 

requirements, usually cost more than the general-purpose resin and 

require the Underwriter Laboratories' approval. 

1. Orthophthalic Resins 

Orthophthalic resins are often called general-purpose polyester 

resins. The difference between orthophthalic and isophthalic 

resins is in the position of the two COOH (carboxyl) groups in the 

phthalic acid molecule. They are on adjacent carbons (e.g., in the 

ortho-position) in orthophthalic acid, and are separated by one 

carbon (e.g. , in the meta-position) in isophthalic acid. This 

resin provides littl e corrosion resistance. 

2. Isophthalic Resins 

Isophthalic resins are either rigid or flexible unsaturated 

polyester resins and are based on isophthalic acid and glycols of 

various types. These resins are non-fire-*-retardant and are used 

for moderate corrosion-resistance applications up to 180°F. They 

generally exhibit excellent resistance to water, weak acids, and 

alkalies; and good resistance to solvents and petroleum products 

such as gasoline and oil. The flexible isophthalics exhibit a 
P.35 

A-2 

lesser degree of chemical resistance than the rigid isophthalics of 

higher molecular weight. 

3. Chlorendic Resins 

Chlorendic resins are unsaturated halogenated polyester resins 

based on HET (hexachlorocyclopentadiene) acid or chloredic 

anhydride reacted with a stable glycol. 

This resin is suitable for use at elevated temperatures, up to 

350°F and is able to handle aggressive, highly oxidizing 

environments, concentrated acids and some solvents very well, but 

is poor in alkaline service. It can be formulated to achieve a 

Class I fir e rating. 

4. Bisphenol-A 

This is an unsaturated, rigid polyester made by reacting biphenol-A 

with propylene oxide to form a glycol, then reacting the glycol 

with fumaric acid to produce the resin. 

This resin exhibits excellent corrosion resistance to both acid and 

alkali up to 250°F. This is not suitable for strong oxidizing 

conditions. 

5. Vinyl Ester 

Vinyl ester resins are methacrylated epoxies that are very similar 

to polyester. They offer excellent physical strength and, in 

general, much better impact strength than rigid polyester resins. 

These resins exhibit excellent resistance to acids, alkalies, 

hypochlorites and many solvents. They are preferred for filament 

winding, especially for machine-made piping. Laminates are good up 

to 250°F. 

6. Furan Resins 

Furan resins are based on a furan polymer derivative of furfuryl. 

alcohol. They exhibit excellent resistance to strong alkalies and 

acids containing chlorinated organics, and are superior in solvent 

resistance. However, the furan materials are not suitable for 

oxidizing chemicals and should not be used for chromic or nitric 

acids, peroxides, or hypochlorites. Laminates are good up to 

250°F. 

As shown in Table A, polymer resins do not resist al3 environments, 

nor do they respona equally to specific applications. 
P.36 

Resistance 

to Acids 

Resistance 

•to Alkalies 

Resistance 

to Peroxides 

Resistance 

to Hypochlorites 

Resistance 

to Solvents 

Flame 

Retardance 

Thermal 

Insulation 

Ability 

NOTE: A 

A-3 

TABLE A 

COMPARISON OF PROPERTIES OF VARIOUS TYPES OF RESINS 

Iso- Ortho- Halo- Bisphephthalic phthalic genated nol-A 

B CA A 

3 C C . A 

C C A B 

C CA B 

B C B B 

C C A C 

A A A A 

• 

= High, B = Moderate, C = Low 

Furan Vinyl 

Ester 

A B 

A A 

C B 

C B 

A B 

B C 

A A 

Carbon Stainless J 

Steel Steel 

B B 

B B 

C C 

C C 

A A 

A A 

C C 

-
P.37 

A-4 

The types and relative ratios of the various raw materials which are 

incorporated into an unsaturated polyester determine the physical 

properties of the resin. 

Raw materials are mixed in a specific ratio and are heated (cooked). 

The cooked material is called a base resin. The base resin is solid at 

room temperature and is later reduced with monomer (normally styrene) 

which will thin the polyester and eventually react with it. The 

monomer reacts with the base resin because the unsaturated groups will 

react with each other, bridging (cross-linking) the polyester chains 

together until one solid mass forms. The control of this spontaneous 

cross-linking reaction is done with chemical additives called 

inhibitors. Usually enough inhibitor is added to keep the system 

stable (liquid) for a minimum time (three months at 73°F). 

The cross-linking reaction (polymerization) is a chemical process 

affected by several factors such as: temperature, mass, catalysts, 

promoters, inhibitors, and contaminants. Most of the polyester resin 

fabricators use a catalyst in their operation to overcome the inhibitor 

in order to cause cross-linking of the polyester resin. 
P.38 

GLOSSARY 

Definitions 

These are additional definitions for technical terms used by this 

industry. 

1. Catalyst is a substance added to the resin to make it cure 

more rapidly. 

2. Cross-linking is a process of joining two or more polymer 

chains wnich converts a thermoplastic to a thermosetting 

plastic. 

3. Cure is the polymerization or the transformation from the 

liquid to the solid state of the resin to achieve the desired 

physical properties, including hardness. 

4. Fiberglass is a fiber similar to wool or cotton, but made from 

glass. 

5. Gel Coat is a surface coat, either colored or clear, which 

provides a cosmetic enhancement and exposure protection. 

6. Inhibitor is a substance designed to retard or prevent a 

chemical reaction. 

7. Polymer is a large chemical chain composed of identical 

cross-linked groups, such as polystyrene. 

8. Resin is any of a class of organic polymers of natural or 

synthetic origin used in reinforced products to surround and 

hold fibers, and is solid or semi-solid in the cured state. 

9. Thermoplastic Materials are those materials that repeatedly 

soften when heated and harden when cooled. 

10. Thermoset Materials are those materials that undergo an 

irreversible chemical-curing reaction by the action of heat or 

catalyst. 

1i. Vapor Suppressant is a substance added to the resin to 

minimize the outward diffusion of monomer vapor into the 

atmosphere.