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News in resins, fibers & additives.

Regardless of the ups and downs of the economy, the annual SPI Composites Institute show and conference is the premier forum for introducing new materials for industrial reinforced plastics/composites. At this year's event, held recently in Cincinnati, some of the news highlights included a highly innovative, cost-saving polyester tooling material, a new entrant in vinyl ester suppliers, low-styrene-emitting resins, and several new reinforcements and core materials. (More show news is contained in our preview report--PT, Jan. '92, p. 35. And next month, we'll review machinery news from the meeting.)

NEW RESIN CUTS TOOL COSTS

Perhaps the most dramatic new material at the show was Polylite Profile 33540-00 tooling resin from Reichhold Chemicals, Inc., Research Triangle Park, N.C. This resin is said to make possible a whole new way of fabricating FRP molds, reducing mold-making time by an average of 80% and cost by 50%, Reichhold says, based on a number of customer trials.

The key to this development is extremely low shrinkage, achieved with a low-shrink/low-profile additive system that functions at room temperature. The result is that this one-component resin shrinks just 0.00024 in./in., or 1/8 in. on a 40-ft mold. According to Reichhold, this means that the tool reproduces the master exactly, with no surface distortion, print-through, or tendency to pre-release. And tools are stress-free, so they are stronger and can withstand higher operating temperatures. They can also be built with lighter-weight support structures.

Whereas typical tooling polyesters require tedious hand lay-up of numerous thin layers to minimize shrinkage, the new system can be sprayed up with chopped glass in thick layers--the minimum layer thickness, in fact, is 0.120 in. in order to provide sufficient exotherm to cure. That's where the big time savings comes in. (The same benefits could be obtained for rapid production of prototypes.)

The new resin costs substantially more than standard resins. However, it is filled with 50% alumina trihydrate, bringing the overall materials cost down to about the same level as normal tooling polyesters. The resin is supplied nonpromoted, allowing the user to tailor gel time (with Polylite 46559 cobalt/amine promoter) for large or small tools. Reichhold also formulated a special ketone peroxide initiator blend (Superox 46750) specifically for this resin system. As a built-in quality-control indicator, the resin system changes from clear to opaque during cure. Reichhold cites a 22-min gel time and 29 min to peak exotherm. The resin is compatible with standard tooling gel coats. (CIRCLE 35)

NEW NAME IN VINYL ESTERS

Owens-Corning Fiberglas Corp., Toledo, Ohio, says it is responding to customer demand by adding two vinyl esters to its line of polyester resins. Developed through OCF's technology exchange with BASF AG and Japan's Takeda Corp., the vinyl esters can be used in hand lay-up, spray-up, pultrusion and filament winding.

Each is available in two versions. Vibrin E-010-01, a bisphenol-A epoxy vinyl ester with 40% styrene, is also available in an E-010-06 version with 30% styrene content.

Vibrin E-085 is an epoxy novolac-based vinyl ester. The standard E-085-01 version reportedly has good resistance to organic solvents and chemicals, while the second version, E-085-02, contains less (30%) styrene. With heat-distortion temperatures between 293 and 296 F, these resins are designed for use at higher temperature and in more corrosive applications than the E-010 vinyl esters. (CIRCLE 36)

Also commercializing a new vinyl ester, this one designed to reduce styrene monomer vapor emissions, was Dow Plastics, Midland, Mich. Derakane 441-400, which was introduced at last year's SPI show as the experimental XU 71928.01, contains a relatively low 33% styrene. Nonetheless, it has lower viscosity than the company's Derakane 411 resins. Also, a modified epoxy backbone gives the new resin about a third more elongation, 25-30|degrees~F higher heat deflection, higher strength, stiffness and HDT, Dow says. Typical properties are: 13,000 psi tensile strength; 7-8% elongation; 24,000 psi flexural strength; 510,000 psi flex modulus; and 245 F HDT. Corrosion resistance is unchanged. (CIRCLE 37)

An unusual series of vinyl ester prepregs is offered by Amersin Div. of American Shoe Machinery Co., Danvers, Mass. These products--consisting of B-staged vinyl ester on unidirectional glass, woven roving, mat or fabric--have been used for many years to make shoe lasts, and now the company is seeking to market them more broadly. The prepregs have a 2-yr shelf life without refrigeration, contain no styrene and are said to cure quickly at 225-400 F. (CIRCLE 38)

In polyesters, Ashland Chemical Co., Columbus, Ohio, says it is developing several low-styrene-emitting resins for marine and general applications, which are planned to be released later this year.

Also, the country's second largest gelcoat producer, Co-Plas, headquartered in Fort Smith, Ark., has a new name--Neste Polyester Inc. This reflects the acquisition of all outstanding stock in the company by Neste Chemicals of Finland, which bought a one-third stake in Co-Plas in late 1990. Neste claims now to be the world's second largest producer of gelcoats.

NEW SMC, BMC COMPOUNDS

In polyester molding compounds, Rostone Corp., Lafayette, Ind., has two new grades. Its latest is Rosite 4060ES, an SMC for large business-equipment enclosures, which boasts 90% greater Gardner impact strength than standard SMC. This very low-shrink, 25% glass-reinforced has Gardner impact of 33.6 in.-lb, notched Izod impact of 12.4 ft-lb/in., tensile strength of 6000 psi, flexural strength of 18,000 psi, flex modulus of 950,000 psi, and UL 94-5V rating. (CIRCLE 39)

Late last year, Rostone came out with Rosite 3554D, a low-shrink, electrical-grade BMC designed to minimize internal pressures generated in electromechanical components during high-current interruption tests. It's aimed at circuit breakers, enclosures for motor starters, and other electrical devices. It has a notched Izod impact strength of 6 ft-lb/in., flex modulus of 1.7 million psi, compressive strength of 22,000 psi, arc resistance of 170 sec, dielectric strength (short-time) of 300 v/mil, and UL 94V-0 rating.

Meanwhile, Glastic Corp., Cleveland, has expanded its economy line of "Super Low Cost" BMC that reportedly sells for 15-25|cents~/lb less than standard medium-strength 94V-O or 94HB compounds. The initial SLC-1000 grade was introduced last June at NPE (see PT, May '91, p. 106). It has an Izod impact strength of 5.2 ft-lb/in., flexural strength of 16,100 psi, compressive strength of 23,800 psi, and shear strength of 3100 psi. Now there's also a SLC-2000 grade whose properties include 17,000 psi flex strength, 4000 psi tensile strength, and 22,000 psi compressive strength. (CIRCLE 40)

REINFORCEMENTS & CORE MATERIALS

There were several new glass products from all major suppliers, as well as an unusual new core material:

* For SMC: New from the Glass Group of PPG Industries, Pittsburgh, is Type 5528 structural roving for SMC, which reportedly reduces sheet loft and fiber prominence in finished parts. This medium-hard, medium-soluble, high-integrity roving reportedly provides minimal static and uniform glass distribution out to the edge of the sheet, allowing molders who previously left a 2-in. edge trim to reduce that to only 1 in. (CIRCLE 41)

* For spray-up: Vetrotex Certain-Teed Corp., Valley Forge, Pa., introduced new Gun Roving 299, a high-performance roving designed for fast wet-out and wet-through to minimize rolling, and low springback and air entrapment for good mold conformity. It's designed to conform to molds with sharp radii or complex and intricate shapes. (CIRCLE 42)

* For hand lay-up: PPG introduced MPM HTX, a chopped-strand mat offering "superior" laminate clarity. Because MPM HTX is designed to eliminate air entrapment in the laminate, rolling or brushing is not necessary, PPG says. It's compatible with polyesters, vinyl esters and epoxies. (CIRCLE 43)

A unique core material that reportedly combines the laminating properties of glass mat with the filling properties of a putty was introduced by ProBalsa, div. of Polimex Group, Grapevine, Texas. Called Spherecore, it comes in thin, spongy sheets of chopped-glass mat interspersed with thermoplastic microspheres. The material can be saturated by rolling out with resin. It's most notable property is that when wetted it is soft and workable and doesn't spring back. It can be worked into tight corners and conforms to complex shapes. It can be worked to a feather edge so that plies can be overlapped easily. Polymix says this core material helps build up thickness quickly, improves surface quality by hiding the pattern of woven reinforcements, requires less resin to wet out than other reinforcements and provides the same stiffness as normal glass mat in laminates weighing one-third less. Trimmed pieces of Spherecore can be mixed with resin to produce a lightweight putty. (CIRCLE 44)

Other core materials are being introduced to composites fabricators by Norfield Corp., Newtown, Conn. The company has produced its NorCore thermoplastic "honeycomb" for years as a lightweight stiffening material and is now seeking composites applications. NorCore can be produced from a variety of thermoplastics, including HIPS, ABS, polycarbonate, HDPE, PP, ionomer, and polyetherimide (GE's Ultem), and in thicknesses from 1/4 in. to 3 in. and sheet sizes up to 5 x 10 ft. It can be bonded to a variety of face sheets, and because it's thermoplastic, it can be heated and formed to a variety of shapes. The company has a new, economical "R" series made from post-industrial recycled HIPS and PC. These cost 25% less than virgin grades. (CIRCLE 45)

Norfield is in the process of being merged into Lunn Industries, Inc., a composites fabricator in Wyandanch, N.Y. Lunn recently purchased the Dura-Core aluminum honeycomb core business of American Cyanamid Co. in Havre de Grace, Md.

* For filament winding and pultrusion: Schuller Glass Fibers, Inc. (the new name of Manville Corp.'s fiberglass business), Toledo, Ohio, brought out Star Rov R505 single-end roving for filament winding and pultrusion. It's designed for use in amine-cured epoxies. R505 is offered in yields of 675,450 and 350 yd/lb. (CIRCLE 46)

* For thermoplastics: PPG's new Type 3540 and 3760 multi-end rovings are designed to be used in various thermoplastics, and are said to be the only North American products of their type based on small-diameter "G"-type (10-micron) filaments. Type 3540 roving, which evolved from PPG's standard 3540 chopped strand, is for reinforcing nylon, PET and styrenics such as SMA, ABS and SAN. Type 3760 is an entirely new product for PBT, which boasts white molded color, good compatibility with flame retardants, uniform dispersion, high extrusion compounding rates, and excellent mechanical-property retention after heat aging. Both reinforcements are available in 52- and 200-yd/lb yields. (CIRCLE 47)

Schuller Glass Fibers introduced what is believed to be the first 1/16-in. chopped glass aimed specifically at thermoplastic matrices (it's also available in conventional 1/8- and 3/16-in. lengths). Star Stran 748 is an E-glass reinforcement designed for use in high-temperature injection molding compounds of PPS and polyetherimide (GE's Ultem) resins. It is manufactured in 10- and 13-micron filament diameters and reportedly offers 10-15% increases in tensile and impact strength over other thermoplastic reinforcements that traditionally have 1/8-in. or 3/16-in. fibers. (At last year's SPI meeting, Manville introduced a version of Star Stran 748 for phenolics, saying it was the first U.S.-made 1/16-in. chopped-glass fiber; see PT, April '91, p. 44). (CIRCLE 48)

Owens-Corning Fiberglas Corp., Toledo, Ohio, says commercial quantities of its 183E chopped strand are now available after successful sampling last fall. It's said to produce substantially whiter PBT compounds than the company's 408 product, resulting from a new sizing, not any changes in the glass itself. (CIRCLE 49)

FLAME RETARDANTS, FILLERS AND MORE

New additives at the show included several types of flame retardants, fillers, and curing agents.

* Flame retardants and fillers: At last year's SPI meeting, ECC International, Atlanta, unveiled a novel filler for BMC called Polarite 420, consisting of a calcium carbonate with a thermoplastic coating that functions as both a filler and low-profile agent and reportedly provides good colorability, to boot (PT, Feb. '91, p. 19). This year, ECC showed off the Polarite 880 series of low-profile polymer-coated alumina trihydrates for BMC. The two grades (white and black) provide flame retardance and smoke suppression as well as reduced cure time, zero shrinkage, high gloss, uniform pigmentation and improved physical properties, the company says.

Compared with untreated white ATH, a 60% loading of Polarite 880E reduces the cure time of BMC molded at 302 F from 65 sec to 36 sec. Flexural modulus goes from 1.24 million psi to 1.51 million psi, and flexural yield strength increases from 6000 psi to 9400 psi. Smoke density remains about the same.

At the same loading level and processing temperature, Polarite 884G (black) can reduce cure time to 57 sec, versus 2 min for an untreated black ATH. Flexural modulus can be increased more than twofold, from 603,000 psi to 1.415 million psi; but flexural strength decreases from 10,240 psi for the BMC compounded with the untreated ATH to 8180 psi for the compound containing Polarite 884G. Again there is only a minor increase (about 1%) in the smoke index. ECC says these additives eliminate the need for a low-profile agent, simplifying the formulation. (CIRCLE 50)

Alcan Chemicals, Cleveland, says its Flamtard H and Flamtard S inorganic tin/zinc flame retardants have proven to be effective alternatives to antimony oxide in a wider range of plastics since they were introduced a few years ago (PT, April '89, p. 63). Besides flexible and rigid PVC, they're now said to be especially effective in halogenated polyesters and nylon. A spokesman says these flame retardants will be joined by another antimony replacement later this year--a magnesium hydroxide that releases its water of hydration (like ATH) at high enough temperature to be useful in a variety of engineering thermoplastics. (CIRCLE 51)

The Solem Div. of J.M. Huber Corp., Norcross, Ga., also notes that its Zerogen magnesium hydroxide-based flame retardants for thermoplastics are finding new markets as processors seek a flame-retardant filler that will allow them to run their extruders faster and hotter. (CIRCLE 52)

Solem also introduced new alumina trihydrates as well as novel uses for some of its established products. Micral 1000 and Micral 1500 are new ATH grades with 1-micron and 1.5-micron particle sizes, which reportedly provide extreme brightness. Solem says they can be provided with a variety of surface treatments, including silanes, stearates, wetting agents and processing aids. (CIRCLE 53)

Solem also exhibited a number of established products that have just recently found new uses. The Modal line of surface-treated ATH has long been used in injection molded and extruded plastics. Now, Solem says, they're finding their way into RTM and pultrusion as users are requiring better dispersion and reduced viscosity in those processes. Solem has even designed a few surface-modified ATHs specifically for pultrusion (see PT, Sept. '91, p. 79). (CIRCLE 54)

Desire for improved viscosity control in molding compounds is finally gaining recognition for another Huber product. Hubercarb W4, a highly pure calcium carbonate, has been commercial for three years, but is just now gaining wider acceptance. According to a spokesman, Hubercarb W4 allows high loading while providing viscosity control of |+ or -~3%, vs. |+ or -~10-20% for other fillers. (CIRCLE 55)

A new player in fillers made its trade show debut in Cincinnati. Polar Minerals of Mount Vernon, Ind., built its first plant last summer and began marketing its first products in the fall (see PT, July '91, p. 25). Polar imports all of its raw materials--for example Chinese talc, which it says provides 3-4 points higher brightness and contains less iron than U.S.-mined talc; and Caribbean limestone and barite as sources for calcium carbonate and barytes. Polar says its products can improve heat aging and impact strengths by 10-15% over many other fillers. (CIRCLE 56)

A new filler that improves thermal conductivity while retaining electrical resistivity is Magotex fused magnesium oxide from Kaopolite, Inc., Union, N.J. It reportedly has a coefficient of thermal conductivity at least 5 to 50 times greater than many types of inorganic fillers. Current uses are mainly in thermosets (epoxy, phenolic and polyurethane), though some customers are testing it in thermoplastics such as ABS and polycarbonate. (CIRCLE 57)

* Catalysts and curing agents: Two long-established thioester antioxidants for thermoplastics reportedly hold new promise as exotherm suppressants in thick polyester or vinyl ester parts. Argus Div. of Witco Corp., N.Y.C., says Mark 5151 and 5152 lower the peak exotherm temperature without significantly affecting gel and cure times. At 0.5-1% levels in a variety of resins, Mark 5152 (with a higher sulfur level and therefore higher efficiency than 5151) lowered peak exotherm by 80-90|degrees~F, with little or no extension of gel and peak-exotherm times.

Lower exotherm can eliminate cracking in resin-rich areas of RTM parts. Other benefits are said to include low toxicity and lighter color in cured laminates, owing to lower exotherm and to the additives' antioxidant effect. In addition, they act as wetting agents for fillers and reinforcements; and their polar organic structure reportedly helps air release. Surface profile is said to be improved in SMC. Prices are around $4/lb. (CIRCLE 58)

A relatively new initiator for vinyl esters is Trigonox 239A cumene hydroperoxide solution from Akzo Chemicals Inc., Chicago. It reportedly is nonfoaming (unlike most MEKPs), and produces lower exotherm and shrinkage, Akzo says. Price is about $1/lb above MEKP. (CIRCLE 59)

Aztec Catalyst Co., Houston, showed its newest initiator, Peracetate-50 OMS (t-butyl peracetate), which can be used in unsaturated polyester, silicone rubber and other unsaturated resins. (CIRCLE 60)

* Coupling agents: Introduced at last year's SPI Composites Institute exhibit as developmental products, Hydrosil silanes from Huls America Inc., Piscataway, N.J., are waterborne silanes that contain no VOCs (PT, Feb. '91, p. 93). This year, Huls announced it had commercialized amine, epoxy, mercapto, alkyl and vinyl-amino versions and was about to introduce methacrylate and vinyl types. (CIRCLE 61)

* Colorants: PDI Colorants, a unit of ICI Americas, Edison, N.J., introduced a new highly concentrated black colorant, PDI 11-88051, that reportedly improves maturation stability and color uniformity in low-profile SMC/BMC. Compared with carbon and iron oxide blacks, PDI's proprietary colorant permits 30% higher color concentration, resulting in lower colorant usage and cost. PDI says 11-88051 is 100% reactive with all FRP systems, resulting in almost no effect on physical properties. (CIRCLE 62)

This month, Mica-Tek, Inc., a new subsidiary of Franklin Industries in Dalton, Ga., plans to introduce its first commercial products. These will be coated-mica colorants designed to produce a choice of glittering, non-glitter, speckled and granite-like effects in thermoplastics and thermosets. They are produced by chemical and heat treatments that convert mica to a "champagne" gold color, as well as metalizing the mica, dyeing it, or coating it with pigmented polymer or other media. These nondusting pigments are intended to compete with colored nylon fibers, thermoplastic colored chips, and perhaps metal-flake pigments. Grades in development include silver, gold, black, green, red, yellow and blue. (CIRCLE 63)
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Title Annotation:Composites Show Report, part
Author:Naitove, Matthew
Publication:Plastics Technology
Date:Apr 1, 1992
Words:3155
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