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Dans Initiator Presentation danl @ 2012-09-12 15:01:40
Initiator Presentation 07/21/2012

Initiators, frequently referred to as catalysts, start the gelling process. Initiator is mixed into promoted resins immediately prior to use or mechanically are injected by spray gun. When practical it is best to pour additives into the vortex while mixing so that they do not cling to the side wall of the container. Initiator is injected into the promoted resin stream in spray-up equipment systems.

CAUTION: Initiator is NEVER mixed with promoters or accelerators. The best procedure is to add initiators to resin that already contain promoter or accelerator. Direct contact of an initiator with a promoter or accelerator can create an explosive condition or cause a fire. Consult the MSDS for each of these materials for safe handling and storage.

MEKP (methyl ethyl ketone peroxide) is the most commonly used organic peroxide initiator. In North America, active oxygen content of MEKP provided by suppliers is typically in the area of 9%. The active oxygen content of organic initiator peroxide varies by geographical region. Fabricators should check with their local organic peroxide initiator supplier for specific active oxygen content guidelines. MEKP is typically used with cobalt napthanate (CoNAP) promoter and DMA/DEA accelerators for room temperature curing of most polyester and vinyl ester resins.
Concentration of isomers/active oxygen variations of MEKP can provide additional cure flexibility with some resin and promoter systems. There are several versions of MEKP, for example, some have low dimer contents and others have high dimer contents. For vinyl ester resins, MEKP initiator with high dimer content is the preferred initiator.

CHP (cumene hydro peroxide ) is principally used with high reactivity vinyl ester resins to provide lower exotherm temperatures and reduced shrinkage. CHP performs well with CoNAP/DMA formulations. CHP is also suitable for some other resins where slower cures are required or thicker laminates are made in a single pass without intermediate cure and exotherm stopping points.

BPO (benzoyl peroxide) is available in powder form, as a paste or in a liquid emulsion. Powders and pastes are difficult to use and control. When BPO is required, emulsions with 40% active BPO content are preferred for use with vinyl ester resins. When determining BPO additive concentration you need to take into account the dilution factor. (Gel time tables are based on 98% active BPO.) BPO initiator with DMA accelerator is preferred for laminates in sodium hypochlorite service in place of conventional MEKP/CoNAP/DMA cure systems. The ratio of BPO to DMA is critical to avoid gel and cure inconsistencies. Post curing is required to achieve complete cure with BPO/DMA.

Cream Hardener is used with all polyester fillers. White BPO formula maintains color of filler to minimize excessive priming. Quick hardening, non-separating, cream hardeners formulated for use with body filler, specialty fillers and polyester finishing putties.

Promoters & Accelerators

CoNAP (cobalt naphthanate) promoter is typically a 6% or 12% solution in an organic solvent.

DMA (N,N di-methylaniline) is used as an accelerator in conjunction with CoNap promoter when using MEKP or CHP initiators or by itself with BPO. DMA is normally provided as a 100% active liquid however 10% active versions are available.

DEA (N,N di-ethyl aniline) can be substituted for DMA in some systems to extend gel times and reduce exotherm temperatures in highly reactive systems. With respect to health safety, DEA is marginally safer than DMA. Consult the MSDS for current status.

Inhibitors & Gel Time Extenders
TBC (tert butyl catechol) is an inhibitor frequently added to styrene monomer to provide longer shelf life purchased in drum quantities. When any styrene containing TBC is added to promoted resin mixes, the resin gel time and cure characteristics may be altered. TBC as purchased is usually 85% active inhibitor and should be used very carefully. A very small amount of TBC can have a significant and inconsistent impact on gel and cure. Addition of small quantities is best controlled using a 5 or 10% solution in styrene and adjusting formulations accordingly.
CAUTION: Care must be taken to prevent TBC solutions from contacting the skin. Refer to the MSDS.

2,4-pentanedione (2,4-P) is a gel time extender or retarder for vinyl ester resins; however, it is also a promoter for polyester resins. 2,4-P is recommended for long gel times because it has minimal effect on the ultimate cure. It is effective for MEKP and CHP initiator systems but is not effective with BPO initiator systems. Caution is needed using 2,4-P. Refer to the MSDS for handling instructions.

Peroxides should always be handled, used and stored with caution. Read and understand all warnings and cautions before using or handling any peroxide product. If in doubt, call the manufacturer before proceeding. Read and understand the Orca Material Data Sheet before using any Solutions peroxide product.

Because peroxides are flammable, they should always be stored in a cool place, away from direct sunlight, heat, flame or sparks. A separate storage area must be provided for large quantities. Store away from promoters, cobalt compounds and accelerators. All storage areas should have sprinklers or a deluge system and must prominently display signs clearly stating “No Smoking, Flammable Storage, Keep Children Away.” Never store in a refrigerator containing food or drinks. Only original containers or containers specifically manufactured to hold peroxide should be used for storage.

Should a peroxide catalyst spill, it must be cleaned up immediately observing the following guidelines:
•Water and fire extinguishers should be available at the spill site and all sources of ignition should be shut off or removed
•No heat. Sparks, smoking, or open flame should be allowed or near the spill.
•Remove all non-essential personnel from the area.
•Cover spill or leakage with inert, noncombustible absorbent material such as Perlite, Vermiculite, sand or clean dirt, then wet with water. If not available, wet sweeping compound or sawdust may be used. Gather up the absorbed material and dispose of properly.


0.50% 5 cc. 0.2 oz. 19 cc. 0.72 oz. 94.0 cc. 3.6 oz. 1.03 liter 40.5 oz. (2.53 lb.)
1.0% 10 cc. 0.4 oz. 38 cc. 1.5 oz. 188 cc. 7.2 oz. 1.03 liter 81 oz. (5.06 lb.)
1.25% 12 cc. 0.5 oz. 47 cc. 1.8 oz. 235 cc. 9.2 oz. 2.59 liter 101 oz. (6.33 lb.)
1.50% 14 cc. 0.6 oz. 57 cc. 2.2 oz. 282 cc. 10.8 oz. 3.10 liter 121 oz. (7.59 lb.)
2.0% 19 cc. 0.7 oz. 75 cc. 2.9 oz. 376 cc. 14.4 oz. 4.14 liter 162 oz. (2.53 lb.)

*Note: Based on resin weight of 9 lb. / gallon.

Composition of Ketone Peroxides
Wt. % MEKP Wt. % MEKP Linear Closed Cup
Material %(O) Wt. % H2O2 Wt % H2O Monomer Dimer Trimer Flash Point F

980 8.9-9.0 0.1-0.4 0.6-0.8 19.1 14.5 19.1 >170
950 8.9-9.0 0.4-0.6 0.6-0.8 29.3 4.6 0 >170
930 5.5-5.56 0.5-0.6 0.4-0.6 17.8 2.8 0 >170
HIPOINT 90 8.8-9.0 1.2-1.4 1.7 19.7 12.4 1.8 >190
M-50 8.8-9.0 2.0-2.5 1.2 25.3 4.9 0.5 >190
MEKP-9 8.9-9.0 0.8-1.0 0.6-1.0 29.0 14.5 0 >170
MEKP-9H 8.9-9.0 0.4-0.6 0.6-0.8 29.3 4.6 0 >170
MEKP-900 8.9-9.0 1.8-2.0 1.0-1.5 27.1 4.2 0 >170
MEKP-925 8.9-9.0 1.2-1.4 0.8-1.2 18 13.6 2.4 >170
MEKP-925H 8.9-9.0 0.1-0.4 0.6-0.8 19.1 14.5 2.6 >170
MEKP-30 5.5-5.56 0.5-0.6 0.4-0.6 17.8 2.8 0 >170

The following initiators are similar in performance. The following information should only be used as a guideline. Contact your Fiberlay representative for product recommendations to meet your requirements.



Ketone / (Monomer) S-950 MEKP-9H 46-702 HI-POINT
90 LP
Ketone / (Monomer) S-950 DDM-9 MEKP-9 46-701 D-50A
Delta-X-9 MEKP-900 46-709 M-50A
DFR FS-100 46-710 FR-222
S-930 DDM-30 MEKP-30 46-730 M-30A
DSW-9 W-60
Ketone / (Dimer) S-980 DHD-9 MEKP 925 46-747 HI-POINT 90 L-50A
Ketone / (Dimer) S-980 MEKP 925H 46-748
Hydroperoxides CU90 CHP 46-727 TRIG K-90 CHP-158
TRIG 239 CHP-5
Spcialty Peroxide Blends
MEKP/Cyclohexanone MEC MEC
Peroxide (CHP) MEC-EX MEC-EX

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