Plastics Engineering Blog

One of the most competitive areas in automotive technologies these days is weight loss. American carmakers need to lighten cars to improve fuel efficiency and offset weight added by more advanced gadgets. European carmakers are under even more pressure to lose weight because they have to reduce CO2 emissions (to 130 g/km) for 65% of new cars starting next year and for all cars by 2015. So chemists, compounders, and engineers are finding creative new ways to replace heavy materials with light.

Here are some of the latest developments in automotive lightweighting, introduced at two current conferences from the Society of Plastics Engineers’ Automotive and Composites Division and Detroit Section in Troy, Mich.–the Automotive Composites Conference & Exhibition Sept. 13-15 (speautomotive.com/comp), and the 2011 Automotive TPO Conference Oct. 3-5 (auto-tpo.com), both held in Troy.

The ACCE conference introduced a new super lightweight continuous-glass thermoplastic molding technology for the first time. The TPO conference features several new technologies to reduce weight by reducing talc, including the first beta nucleation of talc-filled PP and the first part validation of a new magnesium-based fiber. The percentage of weight saving is less dramatic than from glass reduction, but still significant. The ACCE papers will be available free at http://speautomotive.com/aca at the end of the year.

REDUCING WEIGHT BY REDUCING GLASS

At the ACCE conference, a paper from Timo Huber, an engineer at the Fraunhofer Institut in Pfinztal, Germany (www.ict.fraunhofer.de), presented “Local Continuous Fiber Reinforcement” technology for the first time anywhere. (The paper was published in the proceedings for a conference in Marakesh earlier this year, but wasn’t actually given.) The technology places heated continuous glass fiber around metal inserts, only where needed along stress axes in the part and can save up to 80 wt% of glass vs glass-filled PP.

The Fraunhofer Institut’s new continuous glass-fiber molding puts hot glass roving around metal inserts along stress axes in a part, reducing glass content by up to 80%.

Continuous-fiber-reinforced structures have been molded before using woven fiber glass shapes and unidirectional fiberglass tape, like the auto seat system developed by BASF Corp. (www.basf.com) and the French auto parts maker Faurecia (www.faurecia.com), which was originally introduced as a concept at auto shows three years ago. (It was also presented at the ACCE.) Both BASF/Faurecia and Fraunhofer’s continuous glass thermoplastic parts create a separate glass-reinforced structure, place it in the mold, and mold over it. Both achieve dramatic weight savings replacing metal. But Fraunhofer’s cats-cradle approach to glass roving is about as minimal and strategic as glass use gets.

Fraunhofer starts by making unidirectional roving out of commingled PP and glass fiber, first heated, then pulled over three consolidating rollers for even distribution and wetting, and then pulled through a die for shaping. Temperatures in the heating zone, consolidating rollers and die are important to make roving without voids, Huber says. The roving is hand placed over the pins while hot, but in production could be placed by robot. Non-metal pins could also be used, and automotive parts that already have metal thread inserts for attachment points can use these to hold the glass fiber roving. Roving can be designed into structural ribs for further weight saving.

Sample parts with 6.5 wt% unidirectional glass showed higher tensile strength than glass-filled composites with 30% of either long or short glass fiber. Samples with only 2.3 wt% unidirectional glass achieved nearly the same tensile strength as 15% short or long glass composites—approximately 47 MPa for continuous glass vs. 49 MPa for short glass and 52 MPa for long glass. All parts were molded with impact copolymer PP (C711-70RNA from Dow Chemical), which has a MFR of 70 g/10 min.

Two papers present successful cross-linking of PP, which is unusual in itself. At the ACCE conference, Scott Miller, application engineer at Dow Corning Corp., Midland, Mich. (www.dowcorning.com), reported on “Closing the Gap Between PP and PA Composites with New Silane Grafting Technology” (initially presented at the SPE’s ANTEC conference in May). Dow Corning calls it the first successful free-radical silane grafting of PP while minimizing beta scission. Chemical grafting and cross-linking of PP typically break molecular chains and reduce properties. PP can be commercially grafted with chain extenders like maleic anhydride, but these only allow coupling to fibers, not cross-linking.

The patent-applied-for technology (U.S. Pat. Applic. # 20110178198) grafts a silane molecule onto the backbone of the PP chain. Silane-grafted PP can then either couple either with reinforcing fibers, cross-link neat PP, or do both to improve performance. Dow Corning’s silane-grafting technology shows improvements over maleated PP for heat stability, long-term aging, moisture resistance and mechanical strength with fibers, Dow Corning says. It has been successfully tested with glass, flax, hemp, ligno cellulosic, and wood fibers and reportedly improves bio-fiber composites enough to replace glass in some applications.

In the TPO conference, Jesse Baldwin, technical director of Toray Plastics (America) Inc.’s foam division in Front Royal, Va., (www.torayfoam.com), will present “New Cross-Linked Olefin Foams for Soft Touch Automotive Interior Trim Applications.” The patent-applied-for (U.S. Pat. Applic. # 20110014835) ToraSoft foam is a closed-cell PP foam with a combination of extreme softness–70% softer than Toray’s previous PP foams–with good haptics, or sense of touch and feel, good thermoformability, and good rebound characteristics. According to the patent application, it combines an olefin block copolymer with PP, a chemical blowing agent, and chemical cross-linking agent. The extruded sheet is cross-linked with an electron beam and heated for foaming in a molten bed of salt, a process Toray has used since the 1960s for even heat transfer and free foam expansion. ToraSoft, introduced commercially in January 2010, is under qualification and has been specified for upcoming automotive programs for interior trim parts.

WEIGHT-WATCHER RECIPES FOR TPO

Several recent developments introduced at the TPO conference take weight out of TPO parts by reducing EPDM rubber or talc. Philip Jacoby, v.p. of technology at Mayzo Corp., a specialty chemical company in Suwanee, Ga., (www.mayzo.com) will present “New PP Beta Nucleation Technology for Improving the Impact-Stiffness Balance of Neat and Talc-Filled PP and TPO Parts.” Beta nucleation is unusual in the first place. (A few Asian companies also make beta nucleants, but Mayzo believes it is the only maker of beta nucleant masterbatches.) Mayzo’s new third-generation beta nucleant masterbatch, MPM 2000, however, has the highest beta nucleating activity anywhere. It can reportedly produce PP with up to 70% of crystals in beta form. The crystal phase of homopolymer PP is typically over 95% alpha crystalline, which melts at 165 degrees C, and only 5% beta crystals, which melt at 14-15 degrees C lower temperature.

Mayzo’s new high-activity beta nucleant masterbatch can make PP with 70% hexagonal beta-form crystals for greater strength and lighter weight. During thermoforming beta crystals convert to alpha crystals, leave micro voids, and turn the plastic white.

Beta nucleation produces hexagonal crystals in PP, whereas alpha nucleation produces clusters of monoclinic crystals (a rectangular prism with a parallelogram at its base). Hexagonal beta crystals improve impact strength and impart opacity, but lower tensile strength and flex modulus. By improving impact strength of talc-filled TPOs, beta nucleation allows APDM reduction. Mayzo introduced beta nucleant masterbatches commercially six years ago, but the first two versions had the limitation that they couldn’t be used with alpha nucleants like talc, certain pigments, or alpha-nucleated PP, which many resin producers make by adding sodium benzoate, NA-11, NA-21 or the clarifier Millad 3988. Mayzo’s second-generation beta nucleant solved the problem by adding an alpha nucleator “killer,” which prevented interference from sodium benzoate, but did not stop other alpha nucleants.

The new third-generation beta nucleant overcomes alpha nucleation by very high activity of the beta nucleator. Beta-nucleated PP can also make breathable biaxially oriented, waterproof film with densities as low as 0.28 g/cc. During biaxial stretching or thermoforming, beta crystals convert to alpha crystals and form micro voids, making the plastic white without pigment. When thermoforming web scrap is reprocessed, however, the beta nucleant is still present and retains its initial nucleation activity, so new beta nucleant only has to be added for the 50% that is virgin material.

At the TPO conference Wouter Reyntjens, business development manager at Milliken & Company, headquartered in Spartanburg, S.C. (www.millikenchemical.com) is presenting an ongoing OEM validation of a recently introduced magnesium-based synthetic mineral fiber reinforcement. The fiber, called Hyperform HPR803i, was introduced two years ago at the 2009 National Plastics Exposition in Chicago, but this is the first data on a part. HPR803i is 99% magnesium oxysulfate according to the MSDS with high aspect ratio and is sold in powder form. Loaded at 3%-10% with or without talc, it reportedly achieves better scratch resistance than PP with talc alone and weight savings from reduced talc of 7%-20%, depending on part requirements.

Milliken will present data on a developmental B-pillar trim part, made by Mecaplast Group, a tier-one automotive molder in Monaco (www.mecaplast.com), using a compound developed by Inno-Comp Ltd., a compounder in Hungary (www.inno-comp.hu). The compound has 13% mineral loading of talc and HPR-803i with a density of 0.98 g/cc and performs like 20% talc-filled PP for a density of 1.04 g/cc. But it weighs 7% less and has better scratch resistance.

This B-pillar trim part made with Milliken’s recently introduced HPR803i magnesium-based fiber and reduced talc weighs 7% less than 20% talc-filled PP and has better scratch resistance.

First, have a solid prior art case. If you do, there is a much less expensive way to get a patent revoked than litigation. “Even a small patent litigation case in court may run $1 million for each side,” says intellectual property lawyer Steven J. Grossman of Grossman, Tucker, Perreault & Pfleger PLLC in Manchester, NH (www.gtpp.com). Patent lawsuits cost both sides because it’s hard to get cost shifting, he adds, so even the winner will pay a lot.

The less expensive alternative is to ask the patent office to reexamine a patent. “USPTO reexaminations typically cost only about $100,000,” Grossman asserts, including around $2500-$8800 in fees to the USPTO and the cost of a patent lawyer. “They also have an extremely high ‘kill’ ratio,” he adds. USPTO reexaminations are successful for the challenger nearly 80% to 90% of the time (www.uspto.gov/patentsReexamination_operational_statistic_through_FY2011Q).

Patent office reexaminations have been highly successful for the challenger. As of mid 2011, “Inter partes” reexaminations (pie chart) cancelled 45% of patent claims, amended 43%, and confirmed 12%. Source: Grossman, Tucker, Perreault and Pfleger

Grossman introduced the process to a plastics audience for the first time at the Society of Plastics Engineer’s ANTEC conference in Boston in May (see May blog). His presentation on “Recent Procedures Introduced to Challenge Patent Grants at the United States Patent and Trademark Office” explains how it works. A CD of all ANTEC papers is available to non-attendees for $150 from the SPE (www.4spe.org).

USPTO reexaminations are intended to streamline the complaint process and reduce the burden on federal courts. They have been around in some form for 30 years, but are still little known and little used because of several limitations.

One limitation is that they can be based only on prior art, the same criteria the patent office uses to grant patents in the first place, specifically “prior written art consisting of patents or printed publications.” A patent office reexamination can’t use legal discovery or depositions the way a lawsuit could. So if a challenger’s issue is prior manufacture or sale of the technology, for example, or a suspicion that the patent holder misrepresented facts to the patent office, these arguments can’t be raised in a reexamination.

WHICH TYPE OF REEXAM TO USE?

The USPTO offers two types: “ex parte” and “inter partes,” which are quite different. “Ex parte,” the original form, was instituted in 1981 and can be used to attack any issued patent. “Inter partes” reexamination was authorized by Congress in 1999 and is limited to challenging patents filed after Nov. 29, 1999.

A bigger difference between the two is whether the challenger is involved. “Ex parte” means “without” the challenger involved. The challenger isn’t allowed to see or comment on the patent holder’s response to the prior art issue, which gives the patent holder the upper hand.

“It’s a little like firing a cruise missile without control,” comments Michael Brown of Brown & Michaels PC in Ithaca, N.Y. (www.bpmlegal.com), who hasn’t brought any patent office reexaminations himself, though others in his firm have. “Unless you have absolutely solid prior art, the examiner will examine the art you have cited and issue an office action. That office action goes to the patent holder, who then responds to it. If the patent holder can amend their claims, you have allowed the patent holder to keep their patent. It’s this lack of control that bothers some people,” notes Brown.

“Inter partes” reexamination means “between” the patent challenger and the patent holder and offers a more level field. The challenger can see the patent holder’s response and file comments on it in return. “The requestor is allowed to remain fully active in the proceeding and continue to raise arguments against the patent holder as the patent holder attempts to overcome the cited prior art,” Grossman explains.

Not surprisingly, both the overall success rate and patent “kill” rate for “inter partes” reexaminations are higher. Inter Partes Reexamination Certificates favor the challenger 88% of the time vs 77% for “ex parte.” “Inter partes” also cancels four times more patents—45% for “inter partes” vs 11% for “ex parte.”

In the first five years that “inter partes” reexaminations (black) were available, there were only 53 vs around 1700 “ex parte” requests (diagonal lines). Both are still far below patent office projections (vertical lines). Source: Grossman, Tucker, Perreault and Pfleger

The mixture of outcomes for the two types is also different. “Inter partes” certificates have cancelled patent claims 45% of the time, amended patent claims 43% of the time, and upheld them 12% of the time. “Ex parte” certificates, on the other hand, have cancelled patent claims only 11% of the time; amended them 66% of the time; and upheld them 23% of the time. So the patent survival rate for “ex parte” is nearly double that of “inter partes.”

The patent office projected 400 “inter partes” reexaminations in 2000, the first year they were available, and got 0. Growth has been slow even though they cost a fraction of the cost of litigation. Source: Grossman, Tucker, Perreault and Pfleger

It’s sometimes hard to pick clear winners because reexamination certificates can combine all three outcomes. “If the patentee has to amend his claims so that your product no longer infringes, you win, even if the patent survives the reexamination,” notes Brown.

Even with a mixture of outcomes, both types of patent office reexaminations are highly successful for the challenger in terms of either canceling or amending patent claims. The reason, intellectual property lawyers say, is that the USPTO is so over-loaded. It has a backlog of a year and a half of applications to review (695,086 applications as of June 2011) and only 6,775 examiners to review them, so a lot of patents get approved that shouldn’t have been.

One high profile example of a patent that probably shouldn’t have been is the so called “patent on a stick” (US Pat. # 6360693) for an Animal Toy that looks like a stick of wood. The patent, which certainly looked tongue-in-cheek, but wasn’t necessarily, caused such a furor among intellectual property lawyers after it was issued March 26, 2002, that the director of the USPTO asked for an “ex parte” reexamination.

This patent for a dog toy, known as “the patent on a stick,” was revoked in 2006 in one of the more famous “ex parte” reexamination cases, raising awareness of patent office reexaminations. Source: U.S. Pat. # 6360693

The inventor, Ross Eugene Long III, a California architect, had presented a bunch of ideas to a patent law firm and selected the flavored, potentially injection molded “stick” as the likeliest to be licensed. After Long initially received the patent, he hired an agent to identify prospective licensees. During the reexamination, he tried twice to amend the claims, but couldn’t. Four years later the claims were revoked. It turned out that there were a half dozen previous patents on stick-like items, mostly garden related, but close enough. Long didn’t appeal the decision because at that point he says he had already spent about $20,000 on the project. The unforgettable drawing may, however, have raised awareness of the reexamination process because requests to the USPTO definitely picked up after 2006.

Appeals are also different after “ex parte” and “inter partes” reexaminations. In “ex parte” cases only the patent holder has the right to appeal, not the challenger, a distinct disadvantage for the challenger. The patent holder can appeal either to the Board of Patent Appeals and Interferences in the patent office or to federal appeals court. In an “inter partes” reexamination, both the patent holder and challenger can appeal a decision first to the Board of Patent Appeals and Interferences and then to federal appeals court.

PTO reexaminations can also be concurrent with patent infringement litigation (in U.S. district court) with interesting twists. If the district court decides that a patent claim is valid, and the reexamination subsequently decides the claim was unpatentable, the patent will be cancelled. If, however, a final non-appealable court decision says the patent is invalid, that will stop the patent office reexamination.

During patent office reexaminations of either kind, an alleged infringer can keep selling his product with no immediate penalties until the reexamination certificate is issued and then only if the certificate validates the patent claims. By contrast, in patent infringement litigation, the court presumes the patent is valid, and the alleged infringer may have to stop selling the product if served with a preliminary injunction, Grossman points out. However, if an infringer ultimately loses in court, he still can be ordered to pay damages, which may go back either to the date of the patent grant or the date the suit was filed.

REEXAMINATION, ANYONE?

Activity in both types of USPTO reexaminations has been negligible for years. In mid 2011 a total of only 8129 Ex Parte Reexamination Certificates had been issued in all the 30 years that they have been available. Requests for “inter partes” reexaminations have been even more anemic. There were only 53 in the first five years that they were available, whereas the patent office had projected over 2000. There have still been only 253 Inter Partes Reexamination Certificates issued in all 11 years they’ve been available.

Lately, however, requests for patent office reexaminations are growing at last, presumably buoyed by recent successes for the challenger. Requests for “inter partes” reexaminations totaled 1061 in 2010 with 281 “inter partes” and 780 “ex parte.” Total requests in the first half of 2011 is 572with 180 “inter partes” and 392 “ex parte.”

Congress is currently also considering changing the regulations on patent office reexaminations to augment “inter partes” reexamination with “post grant review.” This would allow challengers to raise more issues against a patent than prior art. “In post grant review, it appears that one could attack the granted patent on the grounds that in addition to prior art arguments, the claimed invention is not supported by the disclosure, or that the claims fail on the basis that they are unclear in scope,” Grossman explains. That would remove a big limitation on the scope of reexaminations and should finally increase their use.