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PEL PLASTICS UPDATE highlights recent progress in key areas of polymer/plastics technology including: catalysis, biopolymers, smart/functional polymers, alloys & blends and polymer modification. A recent issue of PEL Plastics Update follows.


Complimentary Copy
Vol. 6, No. 3
PEL PLASTICS UPDATE
May-June, 1998
By Mort Wallach
ISSN 1094-656X
 

 

RECENT PROGRESS IN POLYMER/PLASTICS TECHNOLOGY

High Performance Materials-Polybenzoxazines (PBZ) a new and versatile polymer family based on phenolic derivatives and primary amines is easily processed into high performance material at reasonable cost. It offers design flexibility, and depending on the monomer choices it has potential applications served not only by bismaleimides and polyimides but also polyesters, vinyl esters, epoxies, and phenolics.

 

  • H. Ishida at Case Western Reserve U. in Cleveland has uncovered this new PBZ class of phenolic resins which have a wide range of properties and can be tailored to various requirements. The polymer is synthesized from inexpensive raw materials by a simple ring opening addition reaction of phenolic derivatives, formaldehyde and primary amines. PBZs based on bisphenol-A and methyl amine or aniline compare well to phenolic and advanced epoxy resins. High performance resins based on 4,4'-dihydroxybenzophenone and aniline compare favorably with thermoset polyimides and typically have lower cost raw materials. Potential applications include aerospace, (Tg~350C), electronic packaging materials, and composite manufacture. A consortium of resin producers and end users is promoting the commercial development. Pilot production is expected within a year with general purpose resins expected to be priced at $1-2/lb and high performance resins $10-30/lb. (Modern Plastics, June, 1998, p. 121).

Biotechnology-Biotechnology is being explored as a viable route to new resin development with the synthesis of a new polyester intermediate from corn-derived glucose as a recent example. The biotechnological approach is aimed at replacing parts of the present petroleum based feedstocks with cheaper, less capital intensive processes based on transgenic plants or microorganisms.

 

  • DuPont revealed at a conference in St. Raphael, France that it expects biotechnology could eventually lead to new classes of polymers capable of replacing more expensive oil and natural gas-based systems. This is in strong contrast to other chemical majors who have severed or separated their chemical units from life sciences. Global technology director Don von Schriltz indicated that biotechnology based on manipulation of genes at the molecular level is potentially useful in both life sciences and polymer-based materials and that it will lead to more productive chemical manufacturing processes with fewer byproducts requiring environmentally acceptable disposal. A present example is a DuPont process to make a new polyester intermediate, propylene glycol (3G), from corn-derived glucose. This potentially more economic route to 3G could provide a new type of polyester - 3GT (T = terephthalic acid) with a competitive advantage. (We note that Shell Chemical Co. has a major development program on this polyester made via classical routes.) Specifically, there exist pathways in natural organisms to convert glucose to glycerol (i.e., propylene glycol), and efforts are underway to convert propylene glycol to 3GT. DuPont partnering with Genencor International, has genetically engineered and patented organisms which are capable of catalyzing the entire process at high yields. (Modern Plastics, July, 1998, p. 14).

Catalysis-With the expanding number of players and products competition is stronger than ever in single-site catalyzed polyolefins and there are various catalytic routes to these products.

 

  • The list of products/uses/and producers in the US includes: LLDPE/film/Dow, Exxon, Phillips & Mobil; HDPE/film/Dow; PP/fibers & nonwovens/Exxon & Fina (Townsend Associates). Comparing the various technologies by catalyst system/activity/catalytic site/polyolefin made/and M.Wt. range, respectively gives: heterogeneous Ti/high activity/ multiple site/PE, PP/broad distribution; heterogeneous Cr/high activity/multiple site/PE/ broad distribution; homogeneous Va/low activity/single & multiple site/EP rubbers/narrow & broad distribution; metallocenes/high activity/single site/PE, PP/narrow distribution; and constrained environment/medium activity/single site/PE, PP/narrow distribution. Clearly there are numerous approaches with considerable product overlap. (P. Morse, C&EN, July 6, 1998, p. 11).

Smart/Functional Polymers-Light-emitting semiconductor devices have been developed wherein all key components are made from polymers and which have potential as flexible display screens for television sets and computers.

 

  • H. Sirringhaus and coworkers at U. of Cambridge, England and Zhenan Bao at Bell Labs in Murray Hill, NJ have both independently developed devices consisting of conjugated polymer field-effect transistors (FETs) linked to polymer light emitting diodes (LEDs), which one day may lead to flexible display screens for televisions or computers. The Cambridge group prepared poly(3-hexylthiophene)-based FET in which the charge carriers move very freely with performance rivaling silicon-based transistors. They built a multilayer device in which the FET supplies current to a polymer LED. The improved properties of the FET are attributed to the orderly way in which the polymer organizes itself. This allows for long stretches of conjugation along the polymer chains and (-( stacking between adjacent chains. Researchers at Bell Labs had earlier employed regioregular poly(3-hexylthiophene) in FETs and also have integrated such FETs with organic LEDs (Z. Bao et. al., Applied Physics Letters, In Press). (H. Sirringhaus et. al., Science, 280, 1741, 1998).

Dendrimers-New developments in dendrimer synthesis has led for the first time to the prep- aration of stable alcohol terminated, aliphatic polyester dendrimers which are highly soluble in polar solvents and can act as precursor to polymers with varied Tg , crystallinity, and solubility.

 

  • J. Frechet and coworkers at U. Cal. Berkeley, the Royal Inst. of Technology in Stockholm, and SUNY, Syracuse have developed the double stage-convergent growth of dendrimers which consist of esterified bis-MPA units [2,2-bis(hydroxymethyl)propionic acid] leading to novel fourth generation dendritic polyesters. In double stage convergent growth, the focal points of the monodendrons are coupled in a divergent manner to the periphery of another monodendron prepared either convergently or divergently. This allows for the first time preparation of a stable alcohol terminated aliphatic polyester dendrimer which is highly soluble in polar solvents. This versatile hydroxyl terminated dendrimer can readily be mod- ified, e.g., as a precursor, dendritic polyesters with different glass transition temperatures, crystallinities, and solubilities can be designed. (Macromolecules, 31 (13), 4061, 1998).

Alloys & Blends-Nylon/PVC blends compatibilized with anhydride functionalized ethylene terpolymers have interesting and useful properties including flame and chemical resistance, and toughness, with possible applications including wire and cable, chemical resistant liners, membranes, and containers.

 

  • G. Hofmann of DuPont has recently reported nylon/PVC blends compatibilized with functionalized ethylene terpolymers. These blends have a useful combination of properties including the flame resistance and toughness of lightly plasticized PVC and the chemical resistance of nylon, as well as superior abrasion resistance, strength, and processibility. Formulations can vary from soft and flexible elastomers to semi-rigid grades. Various nylons investigated include nylon 6, and low melting amorphous nylons, as well as commercial types such as nylons 12, 6/12, 12/12, and proprietary grades. The compatibilizing agents are terpolymers of ethylene, carbon monoxide, and acrylate monomers functionalized with anhydride groups grafted onto the copolymer backbone (DuPont's Fusabond). These types of polymers are capable of reacting with nylon and are known to be miscible with PVC. The PVC together with ethylene terpolymer forms the continuous phase while the nylon is the discontinuous phase. The blends have excellent processibility (e.g., extrusion, injection molding) and certain compositions with superior melt strength have been extrusion blow-molded into cylindrical liter sized bottles. Possible applications include: wire and cable insul- ation and jacketing, chemical-resistant liners, membranes, and containers. (Plastics Technology, June, 1998, p. 55).

Alloy & Blend Patents-Among 1000 patents reviewed during this period, there are several noteworthy inventions involving: polyphenylene ether/polyesteramide blends, melt processible vinyl alcohol polymer blends, and block copolymers of polyolefins with polyurethanes, polyesters, or polyamides and their applications.

 

  • "Blends Of Polyphenylene Ethers And Polyesteramides". C. Bailly et. al. (General Electric Co.) US 5,744,068, April 28, 1998. A thermoplastic resin blend comprises A: a poly(phenylene ether) resin comprising a poly(phenylene ether) resin having orthoester functional moieties; and B: a polyesteramide resin containing > 10 mol% aliphatic moieties. The thermoplastic blends may additionally contain compatibilizers for the polyesteramide and poly(phenylene ether) resins. A blend contained PPE, an orthoester-functionalized PPE and 1,4-butanediol-1,4-diaminobutane-dimethyl terephthalate copolymer. (Chem. Abs. 128: 295456p).

     

  • "Melt-Processed Blends Containing Vinyl Alcohol Polymers". T. Diaz et. al. (Rohm and Haas Co.) US 5,744,546, April 28, 1998. A melt processed blend comprises: (a) 80-98 parts of > 1 first polymer containing > 80 mol% vinyl alcohol repeating units and (b) 2-20 parts of a block copolymer prepared by anionic polymerization of a mixture comprising 20-35% styrene and 65-80% butadiene or isoprene, the block copolymer having been hydrogenated, the block copolymer further containing 1-5% grafted maleic anhydride. The blends have good processibility into sheet, film, injection-molded objects, or fibers. (Chem. Abs. 128: 295453k).

     

  • "Block Copolymers Of Polyolefins With Polyurethanes, Polyesters Or Polyamides And Their Use". J. Horrion et. al. (Advanced Elastomer Systems) Eur. Pat. Appl. EP 837,097, Apr. 22, 1998. Block copolymers, useful as compatibilizers for blends of polar and nonpolar thermoplastic elastomers and polar engineering resins, comprise a chemically modified polyolefin, a thermoplastic polyurethane, copolyester or copolyamide, and >1 chain extender. Thus, Amino PP (modified polyolefin) 20 and Desmopan 786 (thermoplastic polyurethane) 80 parts were melt-mixed in the presence of Grillbond EL 6 (chain extender) 1 part to give a block copolymer having modulus (100%) 7.6 MPa, tensile strength 26.8 Mpa, elongation 497% and MFR (200(/2.16 kg) 3 g/10 min. (Chem. Abs. 128: 295717z).

New Ventures & Alliances-OxyChem and Geon plan to form the largest PVC operation in North America. Meanwhile, DuPont which had announced it's intent to separate from Conoco is rumored to be considering a bid for the oil company from Elf Aquitaine. Also, new metallo-cene catalyst alliances are being formed to exploit the technology, strengthen positions, and reduce the number of infringement disputes.

Occidental Chemical and Geon have signed a letter of intent to combine their PVC businesses. This will form the largest PVC producer in North America with ownership split 76% OxyChem/24%Geon. It will be called Oxy Vinyls with annual capacity of 4.2 billion lb of PVC, 4.8 billion lb of vinyl chloride, and 920,000 lb of chlorine. It is expected that the combination will decrease operating costs by $80 million annually. Geon will receive $110 million in cash and be relieved of $185 million in lease obligations. Also being formed is a separate powder PVC compounding JV, owned 90% by Geon and 10% by OxyChem, moving Geon closer to its goal of becoming chiefly a resin compounder. This deal follows closely on OxyChem's contribution of its petrochemicals business to the Equistar joint venture. After necessary approvals, the major PVC venture is expected to be complete by Jan. 30, 1999.
(M. McCoy, C&EN, June 29, 1998, p. 13).

DuPont's recent separation of Conoco after 17 years, allows for more focus on the materials and life science businesses with the expectation that DuPont will thereby position itself for a life sciences acquisition. However, the new DuPont will again be dominated by polymeric materials with its historically large fibers division, e.g., 30% fibers, 27% polymers, 17% chemicals, 15% life sciences, and 11% diversified. DuPont's goal for life sciences is to double in size to 30% of the business by 2002. Meanwhile, it is rumored that DuPont plans to sell Conoco to the French oil company Elf Aquitaine with a possible swap in part for Elf's pharmaceutical business-Sanofi.
(M. McCoy, C&EN, May 18, 1998, p. 5 & Aug. 24, 1998, p. 29).

New catalyst alliances and joint ventures (JVs) have been formed to exploit metallocene single-site technology thereby strengthening and better defining positions. Exxon Chemical and Dow Chemical continue to dominate this technology, while Hoechst also has a strong patent base that it has leveraged with alliances. Through an alliance or JV, companies can combine their intellectual property to create a stronger force in an area where many patents have been filed and several disputes have arisen. The creation of Univation Technologies between Exxon and Union Carbide in a polyethylene joint venture has made the patent estate broader and stronger. Quick response is also important, as an alliance can facilitate rapid access to a market before the competition. Dow-DuPont Elastomers offers a good example wherein Dow was looking for an applications and channel-to-market partner for its technology and DuPont offered market leadership, knowledge of the industry, and a strong product portfolio. Targor, the PP joint venture of Hoechst and BASF is another example whereby the JV has access to extensive resources which can help develop new products more rapidly. As a result the lines between companies, markets, and technologies are blurring in single-site metallocenes and clarifying the scope of these relationships is an important task. Here are some of the important JVs or alliances, and licensors/licensees in PE and PP single-site catalysis (Catalyst Group). JV or alliance and polymer focus include: Exxon/Montell/PE, Exxon/Hoechst/ PP, Exxon/Union Carbide/PE, Dow/DuPont/Elastomers, Dow/BP Chemicals/PE, Hoechst/Fina/PP, Hoechst/ BASF/PP, BASF/Shell/PE, Mitsui/Sumitomo/PE, Mitsui/Ube/PE; licensors/licensees include: Exxon to Mitsubishi/PE, Exxon to Borealis/PE, Exxon to Mitsui/PE, Phillips to Fina/PE, Montell to Dow/PP. (C&EN, July 6, 1998, p. 12).

 

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