Eastman Copromotersfor Effective Polyester Cure

• Rapid, Complete Cure• Low Color• Low Toxicity

Effective PolyesterCure With EastmanCopromoters

• N,N-Dimethylacetoacetamide (DMAA)• Ethyl Acetoacetate (EAA)• Methyl Acetoacetate (MAA)• Acetoacetanilide (AAA)

Jet ski photograph courtesy of Yamaha Water VehiclesCypress, California

Yacht photography courtesy of Hatteras YachtsHigh Point, North Carolina

Motor home photograph courtesy of Tiffin Motor Homes Inc. Red Bay, Alabama

For more information, see Eastman Publication GN-407, Eastman Inhibitorsfor the Fiberglass Reinforced PlasticsMarket.

Eastman copromoters provide a complete and rapidcure response in the room-temperature cure of unsat-urated polyester resins. They also impart relatively lowinitial color to cured polyesters; however, since copro-moters in general may affect color stability afterextended weathering, applications requiring optimumcolor retention should be evaluated prior to use.DMAA, EAA, and MAA are noted for their lower levelof toxicity and ease of handling when compared withcommon amine copromoters such as dimethylaniline(DMA).

Unsaturated polyester resins are cured by a free-radical addition reaction. The reaction is initiated bythe use of a peroxide compound that produces freeradicals when heated or in the presence of a promoterat room temperature.

The two primary room-temperature cure systems arebased on either benzoyl peroxide (BPO) or methylethyl ketone peroxide (MEKP). BPO is most oftenpromoted with DMA. MEKP is frequently promoted

Health Hazard Rating(3 = Most Hazardous) EAA MAA AAA DMAA DMA

HMISa 2 3 2 1 3

NFPAb 2 2 2 1 3

Color Imparted to Resin Low Low Low Low High

Physical Form Water- Water- White 20% Aqueous YellowWhite White Powder Solution LiquidLiquid Liquid (Pink-Yellow)

Effectiveness 1 1 2 3 5(5 = Most Effective)

Eastman Copromoters

with a complex of cobalt (e.g., naphthenate oroctoate) and can be copromoted.

The MEKP/metal complex is easily adapted to varioustypes of fabrication processes and is more widely usedthan BPO systems. Copromoters are used to facilitatethe cure of MEKP-initiated reactions. Eastman copro-moters function by coordination with the cobalt pro-moter. They are not recommended for BPO-initiatedcure systems, which do not use metal complexes forpromotion. Without a copromoter, the MEKP systemmay require long production cycles or may fail to pro-vide a complete cure, thus limiting the performance ofthe polyester.

Lower Color and LowerToxicity Than DMA

Effective Cure at Room Temperature

aHazardous Materials Identification System—see Material Safety Data Sheet for explanation.bNational Fire Protection Association—see Material Safety Data Sheet for explanation.

1

Table 1

DMAA can be used as a general-purpose copromoterin most unsaturated polyester resin formulations. Thiscompound is effective for resins based on variouscombinations of propylene glycol (PG), NPG glycol,TMPD glycol, bisphenol A, phthalic anhydride (PA),isophthalic acid (IPA), and maleic anhydride (MA).Data in Tables 3–6 demonstrate the effectiveness ofDMAA compared with DMA as a copromoter for sev-eral different unsaturated polyester resin formulations.Data in Tables 3 and 4 indicate that DMAA at 0.3 wt% is comparable to DMA at 0.1 wt % in PG/PA/MAand PG/IPA/MA resins. DMAA is slightly more effec-tive than DMA at equal concentrations in a bisphenolA resin (Table 6), and the DMAA concentration canbe increased in this system to obtain better overallcure. Although DMAA is supplied as an aqueous solu-tion, no detrimental effects on cured polyester werenoted during evaluations conducted in Eastman labo-ratories.

DMAA

2

O O CH3

CH3—C—CH2—C—N—CH3

N,N-DimethylacetoacetamideCAS No. 2044-64-6

Molecular Weight: 129.2Empirical Formula: C6H11NO2

EAA

O O

CH3—C—CH2—C—O—CH2—CH3

Ethyl AcetoacetateCAS No. 141-97-9

Molecular Weight: 130.1Empirical Formula: C6H10O3

EAA and MAA are low-color, low-viscosity liquids thatare readily soluble in styrenated resins. They areapproximately equal in effectiveness as copromoters.The data in Tables 3 through 5 compare EAA andDMA as copromoters for three unsaturated polyesterresins and show that EAA must be used at higher concentrations than DMA to approach equal effective-ness. Some resins may require EAA or MAA concentrations as high as 1 wt % to obtain effectivecure development. Unsaturated polyester resinscopromoted with EAA or MAA have lower color thanthose which use DMA (Figure 1), providing a distinctadvantage in many applications.

Because they are difficult to cure, most styrenatedbisphenol A resins are copromoted. The data in Table 6compare the effectiveness of DMA, EAA, and MAA ascopromoters for a styrenated bisphenol A resin. Thedata indicate that bisphenol A resins copromoted withEAA or MAA develop desirable hardness more rapidlythan do resins copromoted with DMA at equivalentconcentration. Extended gel times are also obtainedwith EAA or MAA, compared with DMA. At the sametime, EAA or MAA will provide the slower gel timesthat are necessary for most fabrication processes.

3

MAA

O O

CH3—C—CH2—C—O—CH3

Methyl AcetoacetateCAS No. 105-45-3

Molecular Weight: 116.1Empirical Formula: C5H8O3

AAA

O O H

CH3—C—CH2—C—N— Acetoacetanilide

CAS No. 102-01-2Molecular Weight: 177.2

Empirical Formula: C10H11NO2

Eastman copromoters, which are acetoacetates, donot contain an amine group in the molecular struc-ture; therefore, they do not impart brown color to thepolyesters as amine promoters do. Toxicity tests ofMAA and EAA reveal that they constitute relativelylow hazards by inhalation and by skin contact. Typicalproperties of MAA and EAA are given in EastmanPublication DK-1, Methyl Acetoacetate and EthylAcetoacetate.

AAA is a white powder that is soluble in styrenatedresins; however, agitation for 1 to 2 hours may berequired for complete solution at room temperature.AAA is also soluble (up to about 40%) in DMAA andhas been used in a 70/30 ratio of DMAA/AAA. Datain Tables 3–6 show the effectiveness of a DMAA/AAAsolution compared with DMA as a copromoter forfour unsaturated polyester resins. The informationindicates that the DMAA/AAA blend at 0.3 wt % level is comparable to DMA at 0.1 wt % level inPG/PA/MA and PG/IPA/MA resins. DMAA/AAA issuperior to DMA at equal concentrations in a resin prepared from NPG glycol/IPA/MA and in a bisphenol A resin.

The effect of various Eastman copromoters on the ini-tial color of a cured white gel coat system is com-pared with that of DMA in Figure 1. The informationclearly demonstrates that the Gardner b color value of gel coats cured with Eastman copromoters is nomore than one-third of those produced with similar systems copromoted with DMA, which is used atlower concentrations.

Eastman Copromoters ImpartLower Initial Color to CuredPolyester Systems

Eastman copromoters are useful in the MEKP-initiatedroom-temperature cure of unsaturated polyesterresins, particularly in specialty resin formulationsbased on NPG glycol, TMPD glycol, propylene glycol, and bisphenol A.

Since the overall performance of an unsaturated polyester resin depends on many variables, Eastmansuggests that as a producer/fabricator you use thisinformation as a guide. By applying your own tech-nology, you may receive the benefits of long pot life,extended gel time, good cure, low color, and rela-tively low toxicity that the Eastman copromoters offer.

Summary WARNING:Catalyst (methyl ethyl ketone peroxide) must never bemixed directly with promoters (cobalt octoate or naph-thenate) or copromoters (N,N-dimethylacetoacetamide,acetoacetanilide, ethyl acetoacetate, or methyl aceto-acetate) because violent decomposition may occur. Thecatalyst and promoters must always be added sepa-rately to the polyester resin. The order of additionshould be to add the promoter(s) first, followed by thecatalyst. Care must be taken to thoroughly mix the pro-moter(s) with the resin before adding the catalyst.

DMAA EAA MAA AAA

Physical Form Liquid Liquid Liquid Powder

Assay, Wt % 79–83 99.5 99 99.5

Molecular Weight 129.2 130.14 116.12 177.2

Color 350 Pt-Co 15 Pt-Co 25 Pt-Co White to Off-White

Suggested Concentration, Wt % 0.2–0.5 0.3–1.0 0.3–1.0 0.3–0.7

Comments on Use General- Low color. Similar Must be agitatedpurpose Excellent in to EAA. for dissolution

copromoter. bisphenol in styrene.Low color. A resins. Soluble to 40%

in DMAA.

Eastman Copromoters

aProperties reported here are typical of average lots. Eastman makes no representation that the material in any particular shipment will conformexactly to the values given.

aNPG glycol/IPA/MA (1:1) resin containing 45% styrene. Gel coat prepared with 20% TiO2 and 1.5% fumed silica (thixotropic agent).bDegree of yellowness

Table 2a

Figure 1Effect of VariousCopromoters on theColor of a CuredWhite Gel Coata

Control DMAA AAA EAA MAA DMA0.3% 0.5% 1.0% 1.0% 0.2%

0.2 0.3 0.4 0.4 0.6

1.85Gardner b Color Valueb

4

5

Product LegendIPA = isophthalic acidMA = maleic anhydridePA = phthalic anhydridePG = propylene glycol

Cure Legend (50 g resin in a paper cup)

GT = gel timePE = peak exotherm temperature

TPE = time to peak exotherm after gel

Eastman Publication ReferenceDK-1 Methyl Acetoacetate and Ethyl AcetoacetateDK-2 N,N-DimethylacetoacetamideGN-407 Eastman Inhibitors for the Fiberglass Reinforced Plastics MarketINK-12 Acetoacetanilide

aValues given are weight percent concentrations.bBarcol hardness measures made on 50-g cured resin samples in half-gallon paint can lids.c70:30 Ratio

Cure Development With Various Copromoters

Cure Systema Cure Parameters Barcol Hardness6% GT TPE PE Developmentb

Copromoter Cobalt MEKP min min °C (°F) 1 h 2 h 24 h

3 PG/PA/MA Resin (42% Styrene—300 ppm Tecquinol Hydroquinone)

DMA 0.1 0.3 1.0 8.2 3.5 177 (350) 37 40 40DMAA 0.3 0.3 1.0 10.8 5.0 174 (345) 37 38 40DMAA/AAAc 0.3 0.3 1.0 10.2 6.0 180 (355) 40 40 40EAA 0.5 0.3 1.0 21.3 8.0 174 (345) 10 25 25

4 PG/IPA/MA Resin (42.5% Styrene—250 ppm Tecquinol Hydroquinone)

DMA 0.1 0.4 1.0 7.2 3.0 185 (365) 40 40 40DMA 0.3 0.4 1.0 5.0 2.5 152 (305) 25 30 30DMAA 0.3 0.4 1.0 7.2 3.5 188 (370) 40 40 40DMAA 0.5 0.4 1.0 5.2 3.0 193 (380) 40 40 44DMAA/AAAc 0.3 0.4 1.0 8.9 4.0 185 (365) 40 40 40EAA 0.5 0.4 1.0 19.5 3.0 157 (315) 40 40 40

5 Resin Based on NPG Glycol/IPA/MA Resin (45% Styrene—300 ppm Tecquinol Hydroquinone)

DMA 0.3 0.5 1.0 7.5 5.0 160 (320) 20 20 20DMAA 0.3 0.5 1.0 13.1 5.0 185 (365) 40 40 40DMAA/AAAc 0.3 0.5 1.0 12.8 7.0 180 (355) 35 35 40EAA 0.5 0.5 1.0 25.9 9.0 177 (350) 0 0 10

6 Bisphenol A Resin (Commercial, Unpromoted Resin—50% Styrene—100 ppm Tecquinol Hydroquinone)

DMA 0.3 0.8 1.5 4.6 3.0 174 (345) 10 10 10DMAA 0.3 0.8 1.5 4.4 4.5 182 (360) 15 15 15DMAA 0.5 0.8 1.5 2.6 4.0 185 (365) 30 35 35DMAA/AAAc 0.3 0.8 1.5 5.1 6.0 182 (360) 20 20 20EAA 0.3 0.8 1.5 22.2 9.0 185 (365) 20 25–30 30MAA 0.3 0.8 1.5 22.5 7.0 182 (360) 30 30 30

Table

Eastman Chemical CompanyWorld HeadquartersP.O. Box 431Kingsport, TN 37662-5280U.S.A.

Telephone

From U.S.A. or Canada800-EASTMAN (800-327-8626)

From other locations (1) 423-229-2000

Material Safety Data Sheets providingsafety precautions that should be ob-served in handling and storing Eastmanproducts are available on request. Youshould obtain and review the availablematerial safety information before han-dling any of these products. If any mate-rials are mentioned that are not Eastmanproducts, appropriate industrial hygieneand other safety precautions recom-mended by their manufacturers shouldbe observed.

Neither Eastman Chemical Company norits marketing affiliates shall be responsiblefor the use of this information, or of anyproduct, method or apparatus mentioned,and you must make your own determina-tion of its suitability and completeness foryour own use, for the protection of the en-vironment, and for the health and safety ofyour employees and purchasers of yourproducts. No warranty is made of the mer-chantability or fitness of any product, andnothing herein waives any of the Seller’sconditions of sale.

Eastman, NPG, Tecquinol, and TMPD are trademarks of Eastman Chemical Company.

© Eastman Chemical Company, 1995.

ECP 6107M 4B (9-95) Publication GN-396A Printed in U.S.A.September 1995