Sweet Composites, 6211 Ridge Drive, Bethesda, MD 20816-2641 USA
301-229-2201  –  9:00 a.m. to 5:00 p.m. Eastern, Mon.-Fri.

Last Update: 19 January 2008

Vinylester & Polyester Resin

Please be advised that we no longer sell any polyester or vinylester resins or gelcoats. We maintain this page because it provides a “user-friendly” MSDS for these products, along with some basic guidelines for their use with MEKP and pigments. Please refer to the manufacturer’s documentation for complete technical information. Material Safety Data Sheets are available for viewing and download directly from the manufacturers for some products, assuring the latest information. The MSDS for the Dion 9800 [previously Atlac 580-05A] vinylester resin that we used to sell is available in PDF format from Reichhold. You must have Adobe Acrobat Reader installed to be able to access this file.

Vinylester is stronger and more resilient than polyester resin, which results in tougher laminates. It is supplied by most manufacturers unpromoted, though it may have an accelerator, such as dimethyl aniline, added. The vinylester resin that we previously sold was available promoted, with 0.4% of 6% cobalt naphthenate [CoN] solution added, and promoted-thixotropic, which also contained 1% Aerosil. The Aerosil helps to reduce drainout on vertical mold surfaces. We recommend the use of non-thixotropic resin for vacuum bagging and the thixotropic version for all contact layup applications. Aerosil settles out; shake or stir thixotropic resins before use. Some commercial resins, known as “surfacing” resins, contain wax. It is important that resin used for lamination of successive layers is free of wax.

Polyester and vinylester resins are actually solutions of the solid resin in styrene monomer [CAS #100-42-5], and may contain small amounts of other ingredients such as dimethyl aniline, cobalt naphthenate, and fumed silica. Resin solution is a viscous liquid with a pungent odor. Hazard classification: Flammable liquid, class 3. ID No.: UN-1866. Quart and gallon cans may be shipped by UPS as an ORM-D (No HazMat fee). A five-gallon jug may be shipped by UPS as a Hazardous Material, requiring special shipping papers and payment of a HazMat fee.

Transportation Emergency: Phone CHEMTREC 800-424-9300 Day or Night.

Polyester and vinylester resins [hereafter “resin”] should be stored in a cool place away from all sources of heat, sparks, or flames, and out of direct sunlight. Nominal shelf life is three months but that can be greatly extended if it is stored in a filled, sealed, glass or metal container kept in a cool, dark place. However, at elevated temperatures polymerization may take place which could rupture a closed container. The vapor density is heavier than air. Flash point 89°F.

Resin is an irritant to skin, eyes, and mucous membranes. Inhalation of vapors and/or absorption through the skin may cause liver and kidney damage and could possibly lead to cancer. Work areas should be ventilated to reduce vapor concentrations. Users should wear gloves, goggles, protective clothing, and an approved charcoal-cartridge respirator. Avoid swallowing and all contact with eyes. Avoid prolonged or frequent contact with the skin. If swallowed do not induce vomiting; seek immediate medical aid. Flush eyes with copious amounts of water; seek immediate medical aid. Incidental skin contamination may be removed with a waterless handcleaner followed by thorough washing with soap and water.

Be sure all promoters and accelerators and pigments are thoroughly mixed into the resin before adding MEKP [catalyst]. These agents should never be mixed directly with MEKP as violent decomposition and fire could result. When adding pigments to resin, use as little as possible to achieve the desired result but never more than 5% by weight. Stir MEKP into the resin slowly and carefully to avoid splashing.

Spilled resin should be absorbed with materials such as sawdust, vermiculite or sand. Small residues may be wiped up with acetone and a rag. All contaminated material should be placed in a closed container and kept out of doors and away from combustibles until it can be removed by qualified hazardous waste personnel. In case of FIRE, spray with water [preferably with a fog nozzle], dry chemical, CO2, or foam from a safe distance.

Guidelines for use of MEKP with Dion 9800 vinylester resin containing 0.4% of 6% CoN:
Minimum for a slow cure, or for very thick sections, or for high temperatures0.75%
Normal for boat layups at moderate temperatures (20° to 25°C)1.5 to 2.0%
Hot batch for single layers or small patches or for low-temperature use3.0 to 4.0%

Vinylester from other manufacturers, or the same resin with a different amount of promoter, may require more or less MEKP. The amount of MEKP listed above should be reduced by about 20% for comparable gel times with typical polyester resins. Do not exceed 2% with NPG gelcoats to prevent premature gelation. These must be taken as guidelines only. You are advised to carry out your own tests before starting large-scale work. You must consider the desired gel time, as well as the temperature and other conditions in your shop, whenever mixing resin.

The above information is accurate to the best of our knowledge. However, since data, safety standards, and government regulations are subject to change, and since the conditions of handling and use or misuse are beyond our control, we make NO WARRANTY, either expressed or implied, with respect to the COMPLETENESS or CONTINUING ACCURACY OF THE INFORMATION CONTAINED HEREIN, AND DISCLAIM ALL LIABILITY FOR RELIANCE THEREON. The user should satisfy himself that he has all current data relevant to his particular use.