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Why all the buzz about 'high-crystallinity' PPs?

For 10 years since "highcrystallinity" polypropylene ("HCPP") was commercialized in japan by Tokyo-based Chisso Corp., this unusually stiff and heat-resistant plastic has piqued the interest of competitors and potential customers. In Japan, HCPP now replaces ABS in some appliance and auto parts like interior trim and instrument panels, Chisso says. But in the U.S. it has remained either an expensive import or a developmental material of uncertain availability.

Now, Chisso and its long-time R&D partner Amoco Chemical Co., Chicago, are negotiating a three-year deal for toll production of Chisso's homopolymer HCPP at Amoco's Chocolate Bayou plant near Alvin, Texas, sources at both companies say. This toll agreement is a far cry from what the two companies had originally for when they test marketed a joint venture to make and market the full range of HCPP's at Chocolate Bayou, including copolymers. But Amoco supposedly wasn't willing to invest heavily to build or modify an older-type slurry reactor series to make the HCPP copolymer.

In the meantime, both Amoco and Chisso are also separately poised to announce that each has developed new Pps that equal or surpass the balanced stiffness and heat deflection properties of HCPP.

"Chisso's high-crystallinity resins, with higher stiffness in the base polymer, are one of the most interesting things going on in PP. They're really making a different resin," says Richard Glass, manager of R&D at Ethyl Corp., in Baton Rouge, La., which develops additive packages for PP.

Some market consultants are like-wise impressed at HCPP's potential. Robert Eller, v.p. of Charles River Associates in Boston, who has reviewed the technology and economics of HCPP resins, sees potential markets for U.S.-produced HCPP in replacing talc-filled PP microwave food trays, contact-clear rigid food packages, and automotive interior trim. Mitra O'Malley, business center manager of Phillip Townsend Associates'Detroit office is preparing an extensive confidential client study on the economics of talc-filled PP versus HCPP for automotive interior parts. And Townsend's Houston office is doing a commercial short study of the comparative advantages of various Pps, including HCPP, in microwave trays. Unfilled HCPP is said to match the stiffness of 15-20% talc-filled standard PP. But Chisso sources say HCPP may provide higher practical heat resistance than talc-filled PP in microwavable packaging.

Meanwhile, competitors have been busy developing PP grades duplicating many of HCPP's traits. Some PP makers have emulated HCPP's crystalline structure of fine, densely packed spherulites by means of nucleating agents, whereas HCPP achieves its unusual structure catalytically. However Chisso's international business manager in Tokyo, Paul Murayama, says unmodified HCPP is 10-20% stiffer than competitors'nucleated high-crystalline grades. And Chisso has a few nucleated HCPP grades of its own. Says Murayama, "We can add nucleating agents to our neat resin and be that much ahead of their nucleated resins."



Chisso's HCPP (a trademarked designation) includes some 30 exported grades of homo- and copolymers, including mineral-filled and rubber-modified, for injection molding, sheet extrusion, blow molding, specialty fibers, blown and OPP film. They have been marketed in Japan since 1981, and small-scale import activity in the U.S. has occurred since 1988 (see PT, April '88, p.23,- Aug.'89, p.53,, Sept.'89, P.151).

Chisso and Amoco's two-year joint marketing team, called ACCO, based at Amoco's Chicago headquarters, closed in January. Amoco's people remained at Amoco, while Chisso's people moved to the Chisso America office in Schaumburg, Ill. A senior Amoco R&D source says Amoco decided that "there does not appear to be an attractive enough market for HCPP in the U.S. to justify devoting a plant to it. Processors like the properties, but say they have relatively few uses that require anything that good [at the price]."

During the test market period, over 4 million lb of homopolymer HCPP was made on Amoco's conventional slurry line at Chocolate Bayou, says Murray McKean of Amoco, who was in charge of the joint market test. ACCO had five sales people actively sampling HCPP to end-users, largely for packaging applications requiring high contact clarity, retortability, and microwavability. ACCO's HCPP list price was initially more competitive with standard PP at 55 cts/lb, but rose to nearly a steep premium by the end of the test period. If U.S. toll production starts, however, a Chisso source says the premium should be 10-15% above standard PP.

During the interim, some U.S. customers using HCPP say they switched to other high-HDT resins-such as filled PPs from Mytex Polymers Inc., the Exxon/Mitsubishi Petrochemical joint venture in Farmington Hills, Mich., or polymethylpentene from Phillips 66 Co., Bartlesville, Okla. Anchor Hocking in St. Paul, Minn., used an injection molding HCPP grade (5016) commercially to make microwave cookware. Anchor switched back and forth between HCPP and a competing product depending on price and availability, says Allen Danley, who was responsible for the Anchor Hocking project and is now with another firm.

The simultaneous plummeting of the U.S. economy and price of PP may have obviated the huge investment that would have been needed at Chocolate Bayou in order to produce HCPP copolymers. These HCPPs can't be made in modern slurry reactors that have been converted to so-called "third-generation" high-activity catalyst, says Chisso's Murayama. And HCPP copolymer production takes a series of slurry reactors; homopolymer doesn't. So Amoco's No.1 plant at Chocolate Bayou, with five individual reactors can make homopolymer HCPP, but not copolymer. It would need either a new reactor series or major modification to make copolymers.

A tangled legal situation concerning rights to the HCPP material-involving not only Amoco and Chisso, but also trading company Marubeni Corp. (which imports Chisso resins and catalyst) and possibly Solvay America Corp. (which has patents on a similar catalyst)-apparently also contributed to delays in resolving the fate of HCPP in the U.S.


Informed sources told PLASTICS TECHNOLOGY that under the new agreement being discussed Amoco could produce some 60 million lb of HCPP homopolymer a toll basis at Chocolate Bayou No.1, under a three-year contract, or an average of 20 million lb/yr, though actual amounts aren't fixed. Compounding of HCPP homopolymer grades will be done only by Chisso in the U.S. (probably at Multibase, a French-owned custom and toll compounder in Copley, Ohio, and at Nippon Pigment in Houston). Sources close to the negotiations say most major details have been worked out and the deal could be signed in a few months. Amoco's interest is said to be in marketing neat homopolymer grades for OPP film, food trays, and other disposable applications until its own high-property PP product is ready for market (see below).

Chisso will market filled and modified HCPP homopolymers, as well as imported HCPP copolymers, for durables like automotive interior trim, appliances, and housewares. (Meanwhile, Chisso gave customers letters at the end of the test-market period, committing Chisso to supply HCPP from Japan if not otherwise available.)

Potential advantages to auto parts molders are that, unlike ABS, HCPP doesn't need painting for protection from sunlight, thus saving time, paint and the cost of emissions control. For thermoformed packages, HCPP is said to have broader molecular-weight distribution than other higher-crystallinity PPs and therefore less tendency to oven sag. Chisso says downgauging and reduced cycle times are also possible.

Trio Products Inc. in Elyria, Ohio, ran two lots of sheet extrusion tests with HCPP, making 0.020 gauge clear sheet out of HCPP 16-1811V flex modulus of 276,000 psi and HDT of 262 F at 66 psi). Rolls were then sent to Inline Plastics in Milford, Conn., to form clear, microwavable food packages. Trio president Thomas Bennett says the impact was poor on both lots. "As the material was being trimmed on the bed, operators noted the edges of the sheet were cracking," which he attributes to the grade's high (5.8 g/10 min) meltflow rate. "No question, the clarity was great. We didn't have to use any special processing tricks to obtain it," Bennett says. "Once Amoco and Chisso get their ducks in a row, this material could really be interesting."

Possibly the first U.S. auto part using Chisso's HCPP is being developed. Trials with a lot of different HCPP materials will start in the new model year in September for interior trim for a 1993 Nissan, according to Tetseu Endo, head of R&D for Neaton Auto Pro Manuufacturing Inc. in Eaton, Ohio, a unit of Nihon Plast of Japan (which specifies the materials). Neaton injection molds parts for Honda, Nissan, and Freight Liner trucks. Another large auto trim molder for U.S. cars asked for samples of HCPP 5230 for testing and for a year has been told it's unavailable, even from Japan, says the product development manager. The molder now has Mitex and Himont high-crystallinity PP in production auto parts.

As for the future, Chisso's Murayama says, "We'd like to be able to make HCPP copolymers in the U.S. or Canada, too, possibly even for export to japan," and indicates the company would still consider joint venture production.


While negotiations continue on production and supply arrangements for HCPP in the U.S., both Amoco and Chisso say they are close to announcing the next generation of high-crystallinity PPs, which will equal or exceed the properties of current HCPP. Amoco's developmental high-stiffness resins, "EPP" (enhanced PP), have been kept tightly under wraps for the last six months at Amoco's Naperville, Ill., R&D center for introduction at NPE last month. They target injection molding, sheet extrusion and thermoforming. The extrusion 9119 grade is commercial now for thermoforming and air-quenched blown film, says Steven Welch, Amoco's v.p. of marketing for PP.

Apparently, homopolymer resins have been made in a reactor-size run at Amoco's recently modified Cedar Bayou plant. EPP is said to offer the same or higher stiffness and HDT, compared to HCPP. "The 6 melt-flow product also looks applicable to blow molding," says William Schmocker, Amoco market development manager.

Chisso also plans to announce a new "super" HCPP within a few months, with flex modulus and HDT properties that "far exceed" all its earlier high-crystallinity grades, says Chisso's Murayama. Super HCPP already has one commercial application: a vacuum cleaner housing on a new Panasonic model in Japan, Chisso says.


Meanwhile, Amoco is involved in a second large Chisso-related venture-construction at Chocolate Bayou of the first plant outside Japan to use the Amoco/chisso gas-phase process (PT, May'91, p. 179). This 330-million lb/yr, two-reactor series will make high-impact PP copolymers that also reportedly resemble HCPP's properties. (Chisso's HCPP is only made in a slurry process.) It is likely that this gasphase plant will ultimately b able make a copolymer EPP material as well, an Amoco R&D source says. The gas-phase process uses Amoco's own high-activity catalyst in place of Chisso's.

Amoco research associate Norman Brockmeir describes the Amoco/Chisso gas-phase copolymers as having "both very high impact strength at low temperature and good stiffness at room temperature." He says the gas-phase process is well suited to handling some of the high-ethylene copolymers that may not flow or fluidize well" in other reactors. He adds that the process also makes homopolymers of unusual properties.

The process generates highly uniform, spherical resin particles of very narrow size distribution, Brockmeier says. The process reportedly yields very well blended material, producing no fish-eyes in later processing and minimal off-spec material during grade changes.

The Chisso HCPP and Amoco/Chisso gas-phase PPs are all a related family of resins, says Richard Tuttle, former head of the ACCO sales force and now located at Chisso America Inc.'s Schaumburg office. Whereas standard PP has a flex modulus around 190-250 kpsi, Amoco/chisso gas-phase homopolymers and copolymers are 10% higher; Chisso's homopolymer HCPP goes up to 260-300 kpsi, with HDTs of 250-270 F at 66 psi; and Amoco's EPP homopolymers are in the range of 315-350 kpsi flex modulus and 260-275 F HDT. Super HCPP also is claimed to have 315-350 kpsi flex modulus and 275-280 F HDT.

Meanwhile, Himont, Shell, Phillips, Quantum, Genesis Polymers and others all offer PPs said to be "highly crystalline" with at least some of the characteristics of HCPP. Genesis in Marysville, Mich., says some of its new materials have particularly good balances of increased stiffness and HDT. And Mytex compounds filled grades of PP that reportedly "closely emulate" many Chisso properties-but not their HDT, Chisso says. In addition, Amoco and Chisso say they're both talking with additional U.S. and European producers about licensing the gas-phase polymererization technology.
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Title Annotation:polypropylene
Author:Schut, Jan H.
Publication:Plastics Technology
Date:Jul 1, 1991
Previous Article:In fillers & reinforcements, the action is at the interface.
Next Article:Processing, performance improvements expected from new EVOH capacity.

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