Materials, reinforcements, additives.

From SMC and BMC to RTM, pultrusion, filament winding, spray-up and hand lay-up, the recent SPI Composites Institute Annual Conference and Expo in Cincinnati presented ample news in resins, molding compounds, reinforcements, fillers, catalysts and other additives. Among the topics covered below are recycled reinforcements and fillers, new developments in low-pressure molding compounds, problem-solving resins and reinforcements for SMC and RTM, long-sought successes in phenolic SMC and pultrusion, and a novel safe-to-handle "dry" form of benzoyl peroxide.

Next month, in Part II of this report, we'll present the new FRP developments in machinery and equipment.

Several resins introduced at this year's meeting were DCPD-hybrid polyesters. Although long successful in open molding for marine uses, resins containing high levels of DCPD have previously been unsuccessful in closed-mold processes because of poor curing behavior and low Barcol development. Now, however, it is possible to take advantage of the very low viscosity and excellent filler/reinforcement wetting properties of polyesters with high DCPD content for SMC, BMC, RTM and pultrusion.

RECYCLED RAW MATERIALS

Exhibiting for the first time at the Expo was the first company in North America dedicated to recycling FRP. Phoenix Fibreglass Inc. in Oakville, Ont., just became fully operational this year with a patented, multi-step mechanical process for pulverizing and fractionating cured SMC and other FRP waste. At present, Phoenix processes material mainly on a toll basis, so that manufacturers get back their own material in a form that can be used as filler or reinforcement in fresh composites.

The Phoenix process currently yields four types of products:

* CSX-2s is glass fiber averaging about 1 in. long, derived from SMC. Light gray in color, it consists of about 49% by weight glass, coated with 24-25% calcium carbonate, and 26-27% cured resin. It costs around 40|cents~/lb, or about half as much as virgin chopped strand, making it economical for use in BMC.

* CSX-2i is a similar chopped-strand product, lighter in color, derived from FRP spray-up waste. It consists of about 48% glass and 52% cured resin.

* PHX-20s is a light-gray, 20-micron powder derived from SMC, containing 30-40% resin, 5% glass, and 55-65% calcium carbonate. This product is being used commercially as a filler in an SMC rear upper inner panel on the 1993 Corvette, molded by GenCorp Automotive in Marion, Ind. GenCorp substitutes this regrind for about 20% of the normal filler content, or 6-8% of total formula weight. (All of the '93 Corvette inner panels ultimately will contain recycled SMC.) The recycled filler costs "in the high teens," says Phoenix marketing v.p. Randy Bastarache.

* PHX-20i is a light-colored, 20-micron powder derived from FRP spray-up, which contains 80% cured resin and 20% glass. Priced at 30-35|cents~/lb, it could be used as a filler in fresh spray-up, suggests Bastarache. A 20% loading produces only 3% loss in physical properties, he notes, because the cured resin apparently bonds to the virgin. (Under a microscope, he says, the recycled resin particles are not distinguishable from the resin matrix.) This product was used at a 24.4% loading in pultrusion trials conducted by Reichhold Chemicals. Good physical properties resulted, according to a paper given at the SPI conference by Reichhold's Sean Walsh.

Another new firm in this area of recycling is EFTEC, Inc. in Newark, Ohio. This spin-off from the R&D consulting organization ISORCA, Inc. in Granville, Ohio, will convert waste reinforcement and other fibers into reinforcing mats and roofing insulation board. EFTEC (which stands for engineered fiber technology) uses a continuous, wet slurry forming process similar to papermaking to lay fibers on a moving screen, after which binder is added and cured in an oven. Different fiber types, lengths and diameters can be uniformly blended, and excellent cross-machine and vertical fiber orientation are possible, EFTEC says. Initial contacts have been with fiber manufacturers and major composite fabricators, both of which have significant waste fiber disposal costs.

ACTION IN LOW-PRESSURE SMC

Low-pressure SMC-type compounds may be headed for the big time. National Composites, Inc. (NCI) of Pittsburgh (formerly called Total Composites) has entered into an agreement with GenCorp Automotive, Akron, Ohio, to jointly develop special low-pressure molding compounds (LPMC) for automotive applications. GenCorp will offer formulation recommendations and perform testing and evaluation of LPMC that NCI will make at its plant in South Bend, Ind. NCI expects to make its first commercial automotive LPMC available late this year, though these products will be for GenCorp's exclusive use.

NCI is licensed to make LPMC with technology from Scott Bader Co. Ltd. of England (see PT, April '90, p. 35). LPMC uses Scott Bader's Crystic Impreg unsaturated polyester resin, which melts at about 194 F, changing from a crystalline solid to a low-viscosity liquid. This resin serves as a mechanical, rather than chemical, thickener for LPMC, providing instant thickening when cooled, stable compound viscosity in storage, and high flowability in a hot mold.

Molding pressures for LPMC are only 100-250 psi. NCI has achieved automotive Class-A finish with LPMC in the lab, but not yet in production, according to v.p. Bryan Jacobson-Reighter. GenCorp will evaluate in-mold coatings with LPMC.

That's not all NCI has been doing with LPMC. Jacobson-Reighter says NCI has formulated fire-resistant phenolic LPMC (also using "a little" Crystic Impreg in the formation) and low-density polyester LPMC down to 1.5 g/cc in production, 1.3 g/cc in the lab. LPMC also has showed novel advantages for making structural composites such as a manhole cover molded from a nine-layer sandwich of LPMC plies alternating with dry continuous-strand fiberglass. Even at more than 50% glass content, the LPMC wets out the dry glass during molding. And by next year, NCI hopes to have a low-temperature LPMC moldable at 185 F in epoxy tools for short-run parts. NCI's LPMC is distributed by Superior Fiberglass and Resins, Indianapolis.

Meanwhile, special large-bed compression presses for LPMC have been developed by John T. Hepburn, Ltd. in Mississauga, Ont. These have larger than normal platens for their tonnage. Lower pressure requirement saves 40-60% of the cost of a standard SMC press of similar part-size capability, and a similar amount in molds, too, says Mechanical Div. general manager Don Eckhart. The first unit built is a 495-tonner with 96 x 48 in. bed, which would be normal for a 1500-ton press. It's destined for a customer in the UK to make lift-truck side frames. Eckhart says an LPMC press needs very fine velocity control: "You don't want to go too fast, because the material is very fluid."

NEW MATERIALS FOR SMC/BMC

There's plenty of other news in resins, reinforcements, and fillers for SMC/BMC, as well as new molding compounds. Several new SMC resins were introduced by Ashland Chemical, Inc., Columbus, Ohio. Arophlex flexible resin system is aimed at vertical body panels where it reportedly provides an unusual combination of flexibility, damage tolerance and surface quality. It reportedly can give a Class-A surface to panels as thin as 80 mils.

Arotech Ternary Resin System is a three-component, high-temperature-resistant, zero-shrink SMC system. It consists of Arotech 1900 polyester, Arotech 2000 vinyl ester and Arotech 2100 low-profile additive. Molders can alter the balance of polyester and vinyl ester components to achieve the optimum balance of cost and premium vinyl ester properties with little or no difference in standard physical properties, even when blended over a wide range, Ashland says.

New Arotech 2000 vinyl ester can also be used alone in low-profile, controlled-shrink SMC and BMC. It boasts heat resistance to 300 F and high elongation. Or, it can be blended with new Arotech 2001 low-profile additive to achieve zero shrinkage. Also new is Arotech 2002 vinyl ester that Ashland says "provides maximum shrink control and the best surface quality available from vinyl ester chemistry, as well as all of the characteristics of Arotech 2000 resin."

Reichhold Chemicals, Inc., Research Triangle Park, N.C., also brought out new SMC/BMC resins. Atlac ITP 31634-00 is an isocyanurate vinyl ester system, designed to work with XLP-6150 low-shrink additive from Union Carbide Chemicals & Plastics Co., Danbury, Conn. This resin utilizes the urethane thickening reaction and is said to provide zero shrink while maintaining corrosion resistance and mechanical properties within 10-15% of those of the original Atlac ITP 31631-00 IVE system.

The new resin is already being used in 65%-glass SMC applications such as truck boxes, bumper beams, cross-car beams and recreational watercraft. Because of the excellent surface quality attained, Reichhold has hopes of demonstrating true Class-A structural SMC with this resin. If successful, that would suggest the possibility of producing a structural SMC bumper beam that would require no cosmetic fascia covering. This resin can also be used in a non-thickenable version (without polyol) for BMC.

In addition, Reichhold is developing a new family of ITP resins based on polyesters, polyester/vinyl ester hybrids, and isocyanurate/polyester hybrids. These reportedly will be more economical than the original Atlac IVE/ITP products but not as heat resistant. The first of these new products is experimentally designated ITP 7776-57.

Also new from Reichhold are two dicyclopentadiene (DCPD) hybrid polyesters for SMC/BMC. DCPD resins feature low viscosity for improved filler and reinforcement wetting. Polylite 31617-00 is the first of several planned high-performance, high-reactivity DCPD resins for SMC/BMC. It's aimed at both structural and Class-A parts and is designed to be compatible with most available low-shrink additives. Polylite 31453-00 is a medium-reactivity, non-thickenable resin for highly filled BMC. Its very low viscosity suits it to use with high-resin-demand fillers like clay or recycled SMC fillers.

Two unusual specialty SMC families are new from Quantum Composites, Inc., Midland, Mich. QC 8800 vinyl ester SMC is said to offer an unusual combination of stiffness (3 million psi modulus) and toughness (41 ft-lb/in. notched Izod). Two makers of artificial foot prostheses are using this compound, as is at least one producer of golf clubs. Price is in the range of $1.50-2/lb.

QCI also reports that it has achieved unprecedented success in formulating phenolic SMC. After some unsuccessful attempts in the mid-1980s, QCI says it has licked the problems that formerly plagued this materials (see Technology Newsfocus for details.)

A relatively new merchant supplier of SMC and BMC compounds exhibited for the first time in Cincinnati. Piedmont Composites of Conover, N.C., was formed in 1990. It offers a range of general-purpose, structural, Class-A, toughened, pigmentable, corrosion-resistant, fire-retardant, high-heat and low-density compounds of polyesters and vinyl esters. Proprietary modifications of its SMC machines allow incorporation of unidirectional rovings and mats.

A new glass roving from PPG Industries' Glass Group, Pittsburgh, reportedly allows a Class-A finish in automotive SMC without the need for in-mold coating. Type 5530 is a medium-soluble, medium-hard roving engineered to provide virtually no fiber read-through in a painted part. PPG says it also provides improved mechanical properties, compared with traditional Class-A SMC rovings, so it can be used in structural parts such as body-panel inners. Ability to use one roving for both Class-A and structural parts can eliminate material changeovers and simplify inventories.

ECC International, Atlanta, unveiled the second generation of its Polarite multifunctional additives for SMC/BMC (see PT, April '92, p. 49). These polymer-coated calcium carbonate or alumina trihydrate products reportedly provide very good shrinkage control, good gloss and low profile. ECCI says no additional low-profile agent or internal mold release is needed. The additives are offered in either white or with pigments in the polymer coating, permitting molding compounds to be deeply colored.

Four new ultra-fine, high-brightness calcium carbonates for SMC and BMC are available from Georgia Marble Co., Kennesaw, Ga. (see New Products section for details.)

A novel additive from Byk-Chemie, Wallingford, Conn., compatibilizes low-shrink components, such as polystyrene or SBS, with unsaturated polyesters. This prevents phase separation during storage. The polar and nonpolar ends of the molecule are said to stabilize the resin system, providing lower viscosity, which in turn aids filler and fiber wetting and improves flow in the mold.

IN-MOLD COATING & ADHESIVES

The Latex Unit of GenCorp Polymer Products, Mogadore, Ohio, added a new in-mold coating to its Gen-Glaze line and introduced two new urethane adhesive systems. The IMC, EC710, is said to reduce streaking in injection molded FRP body panels and is being evaluated by a major auto maker before it is commercialized. GenCorp says EC710 reduces provides a smooth, black, glossy finish with a high DOI.

GenCorp's new adhesives are two-component systems. The first consists of Gen-Tac 302 resin and Gen-Tac 4001 hardener, which produce a fast-curing, high-strength, primerless adhesive system for FRP. The other system is Gen-Tac HT400 resin and Gen-Tac HT4200 hardener, a 1:1 ratio system designed to withstand a 60-min. E-Coat bake-oven cycle at 400 F.

In addition, Aroweld 400/310 is the newest structural adhesive system from Ashland Chemical. This two-part urethane system (1:1 ratio) contains no VOCs and can bond FRP, thermoplastics and PS foam.

RESINS & REINFORCEMENTS FOR RTM

Ashland Chemical says its new Arotran Q-6530 is the first RTM system that can withstand E-Coat bake-oven cycles of 1 hr at 400-425 F and still provide Class-A finish with no glass print-through and without gel coating. According to a paper delivered by Ashland technical specialist Peter Vaccarella, earlier Class-A automotive RTM resins (such as Ashland's 50437) suffered from high-temperature paintability problems, low Barcol development (attributed to the low-profile agent), poor shelf-life stability, and high water absorption, which resulted in "paint pops." The new resin reportedly shows less cracking and crazing at high temperature; develops a Barcol hardness of 25-45 right out of the tool, similar to SMC; has a guaranteed shelf life of three months from time of delivery at 77 F or below; and absorbs only 0.6-0.7% moisture. Its viscosity of 150 cps is said to accept as much as 50% filler. Good bonding performance has been demonstrated in production, Vaccarella said.

Class-A finish without a gel coat is also reportedly being achieved with Reichhold's Polylite 31520-10 in at least two applications: the "sport cap" for Chrysler's new Viper sports car, molded at Aero Detroit Inc., Sterling Heights, Mich.; and side fairings for the Ford HN72 Aeromax truck, molded by Goodyear Tire & Rubber Co. in Jackson, Ohio. This resin is available in a new unpromoted version, Polylite 31520-00. The same performance as 31520-10 is obtained by blending 31520-00 with Reichhold's 46559 proprietary promoter system in a 1:1 ratio. This gives the user greater control of shelf life.

Reichhold has applied its DCPD hybrid polyester technology to RTM. DCPD chemistry provides lower viscosity than can be achieved with isophthalics or orthophthalics, a spokesman says. New Polylite 31502-00 is a g-p, medium-reactivity version with a viscosity of only 55 cps at 56% solids. This permits adding more than 55% calcium carbonate and still maintaining 450 cps viscosity at room temperature. The resin is offered in both MEKP-promoted and BPO-promoted (Polylite 31502-08) versions, both of which gel in 10-15 min at room temperature. Also available are higher solids versions that meet California Rule 1162 and ones with longer gel times for elevated-temperature curing.

Good surface finish in RTM is also said to be possible with a non-thickenable version of Reichhold's new Atlac ITP 31634-00 isocyanurate vinyl ester low-shrink resin system.

In reinforcements, Nicofibers of Shawnee, Ohio, has enhanced its Conformat N-754 and N-758 by optionally attaching a 20-mil or 30-mil Surmat-type surfacing veil to the reinforcement. The veil makes the mat very drapable and easy to place in a mold, especially for complex parts, says Nicofibers. Also, by combining the reinforcement and veil on the same roll, pattern cutting and mold lay-up times are reduced.

PPG's new MPM 2000 is described as a second-generation, multi-purpose chopped-strand glass mat that's about 20% thicker and also more uniform than PPG's earlier MPM mat. It's compatible with g-p and isophthalic polyesters, vinyl esters, bisphenol-A polyesters, epoxies, furanes, chlorendic anhydride resins and other flame-retardant resins.

FOR PULTRUSION, FILAMENT WINDING

For pultrusion, Reichhold has developed Polylite 31026-00, a high-reactivity, DCPD hybrid polyester. It boasts unusually low viscosity, allowing for increased filler and reinforcement content. Reichhold is developing a higher solids version and one incorporating vinyl toluene for higher HDT.

The company also has four new corrosion-resistant resins for pipes and tanks. One is Dion 6162T, a fire-retardant resin said to meet California Rule 1162 limiting VOCs. A reportedly unique aliphatic resin backbone is directly brominated to provide low viscosity and Class I flame spread when used with 5% antimony trioxide.

Also meeting California Rule 1162 is new Dion 9150, a modified bisphenol epoxy vinyl ester designed for products in contact with highly corrosive gasohol fuels. For underground tanks to store gasohol, Reichhold offers new Atlac 490-ACT modified terephthalic resin. It reportedly has better solvent resistance than conventional isophthalics and meets UL standards 1316 and 1746.

Reichhold's new Dion 9480 is designed to provide high corrosion resistance at up to 200 F, in order to meet the latest requirements of the pulp and paper industries. Offered with either 35% or 45% styrene, Dion 9480 is an epoxy novolac vinyl ester with a modified polymer structure that's said to offset the high exotherm and glass compatibility problems associated with epoxy novolac resins.

Good surface finish in pultrusion is said to be possible with a non-thickenable version of Reichhold's new Atlac ITP 31634-00 isocyanurate vinyl ester low-shrink resin system.

PPG introduced a new fiberglass roving for pultruded and filament wound phenolic parts. The roving is the result of joint research between PPG, phenolic resin maker Indspec Chemical Corp. of Harmarville, Pa., and Creative Pultrusions, Inc. of Alum Bank, Pa. Phenolic pultrusion has been hampered by poor surface quality and low mechanical properties. But this project and a similar undertaking by Owens-Corning Fiberglas Corp., Toledo, Ohio, have shown that phenolics can indeed be pultruded successfully. Though resin formulation and processing conditions played important roles, part of PPG's success was due to its new 788 multi-end roving. The company says it gives good strand wet-through and wet-out at resin viscosities as high as 20,000 cps. Composite shear strength, typically a weak point in pultruded phenolics, rose by 600%, the researchers say. When used in filament winding, 788 roving reportedly gives phenolic composites higher crush and tensile strengths and greater stiffness.

MORE RESINS & REINFORCEMENTS

A year after Owens-Corning broke into the vinyl ester market (PT, April '92, p. 42), the company has added a third product to its line. Vibrin E-015 is aimed at the boating industry as a barrier coat to resist hull blistering that frequently occurs close to the gel coat.

Akzo Industrial Systems Co., Asheville, N.C., has introduced Enkamat for use as a core material or "spacer" in composites. It's a three-dimensional matrix of nylon monofilaments fused at their intersections. Placed between reinforcing layers, it acts like a spring, Akzo says, increasing the stiffness of a structure at a given thickness. Because more than 90% of the mat's volume is open space, it will not interfere with resin flow in RIM or other processes. Enkamat comes in weights of 4-8 oz/sq yd, thicknesses of 0.2 to 1.0 in., and widths to 15.6 ft.

CATALYSTS & CURING AGENTS

New from Akzo Chemicals Inc., Dobbs Ferry, N.Y., is Accelerator 383, said to eliminate gel-time drift and increase green-strength development. Neither a metal salt nor a soap, this 4% cobalt complex reportedly shows higher activity than standard 6% or 12% cobalt accelerators, depending on resin and peroxide. Gel times are said to be unchanged from normal, though cure rates are enhanced. Presently imported from the Netherlands, the product will be made here once test marketing is completed.

Aztec Catalyst Co., Houston, introduced a new phlegmatized BPO for curing polyesters, vinyl esters and acrylics. Aztec BPO-25 PG is a novel non-aqueous, 25%-active, free-flowing fine granule, that combines both safety and ease of handling with enhanced solubility in styrene and resins. It is exempt from DOT shipping restrictions and does not need hazardous material storage. Its improved resin compatibility reportedly gives finished parts improved physical properties. BPO-25PG is aimed at RTM, pultrusion, polymer concrete and even SMC/BMC.