Composite Molders

AXEL MoldWiz® internal mold releases will...

· better wet reinforcements

· improve resin flow

· eliminate buildup

· make mold release easy

· improve dispersion of color and filler

· eliminate stress and flow marks

· improve cosmetic surfaces

· yield clean parts, ready for finishing

and for pultrusion, these added benefits...

· reduce pull force

· improve line speed

· eliminate chalking, scaling and scumming

 

Internal Mold Releases (IMRs) for Composite Molding

What is an IMR?

IMRs are materials which are mixed directly into the resin to improve release properties and also improve molding or processing characteristics. They may also be added to gel coats.

Why are IMRs used?

In many cases, IMRs can make using an external mold release unnecessary. Less time spent applying mold release and cleaning molds can translate into significant savings in production time. In addition, IMRs contribute to better gloss and improved wetout of reinforcements and fillers. In pultrusion processes, IMRs reduce pull force and improve line speeds. When added to gel coats, IMRs promote smoother, denser surfaces and this contributes to higher gloss.

Are they suitable for all molding applications?

IMRs require heat to function as release agents. This heat can be generated by the exotherm of the resin, by heated mold surfaces, or by elevated process temperatures. Generally, applications which have minimum temperatures of 150°F/65°C and use metal molds are good candidates for internal mold releases. With FRP molds, adding an IMR to the gel coat will reduce porosity and improve release and appearance of parts, although periodic use of external release agents is still recommended to seal the porosity of the mold.

How do they promote release?

Axel's internal mold releases are proprietary polymer products designed to be partially compatible with resin. This permits some of the IMR to cross-link with the resin during the cure, while the balance is emitted as a vapor, creating the release interface between part and mold. Inter-laminate strength, especially the bond between the laminate and gel coat, is not weakened, because the exothermic heat drives the vapor to the mold surface.

Will IMRs effect the physical properties of molded parts? Will it change their color?

When used in the recommended additive range, IMRs can actually improve physical properties. Because these materials tend to reduce resin viscosity they permit the resin to wetout fiber better and this results in correspondingly stronger matrixes. Better wetout at the mold surface means smoother, glossier parts. Axel's IMRs are effective at very low additive levels and generally have no effect on resin color. If color or fillers are being added to resin, IMRs will make it easier to disperse these materials in the resin mix.

Do IMRs change gel times or cure schedules?

Axel manufactures many different IMRs. Each is resin and application specific. This vast array of products allows us to match a lubricant to the resin and cure which are being used, and this minimizes the effect that the IMR has on gel times and resin cures. We suggest that customers run gel tests with and without lubricant to evaluate any changes prior to using the lubricant in production. Should a radical change occur, a different IMR should be considered.

If an internal mold release is used, will parts need to be cleaned before they can be painted or bonded?

Absolutely not. Molding cleaner parts and having cleaner molds is a great reason to consider an internal.

How are internals added and how much is used?

Internal mold releases can be added to the resin or gel coat by the manufacturer or, they can be added by the end user or fabricator. Axel manufactures IMRs in liquid, powder and pellet form. For composite applications, liquid IMR is added to the less viscous or reactive thermoset component before mixing. The recommended starting point for evaluating mold releases in these applications is 0.5% of the total system weight. In highly filled resin systems, or processes like pultrusion, the recommended range for IMRs can be 0.75% - 1.5%.

Can I use the same IMR in different types of resin? How do I select the right product?

We wouldn't recommend it, and thatís why we manufacture hundreds of formulations. We believe in products engineered to enhance performance and productivity, not generic solutions. Our technical support group (800-332-AXEL, 9-5 EST) backed by our developmental chemists will be pleased to recommend the right product for you, or formulate one to meet your unique requirements. What they will want to know is, what the molding conditions are (temperatures, type of molds etc.), what resin is being used and what type of cure or catalysts are involved. Axel's Composite Molding focus sheet contains a useful chart which describes some major resin/cure categories and suitable MoldWiz internal lubricants. Popular products include: INT-PS125 and INT-EQ6 for polyester and vinyl ester, INT-1846N for amine cured epoxies, INT-1890M for anhydride cured epoxies, and INT-XL51 and INT-389A for gel coats.

MoldWiz is a registered trademark of Axel Plastic Research Laboratories, Inc.