BLOW MOLDING VIRGIN AND REGRIND POLYMERS WITH TITANATES AND ZIRCONATES – 2001
Salvatore J. Monte
Kenrich Petrochemicals, Inc.
140 East 22nd Street
Bayonne, NJ 07002Abstract
In addition to universal filler/pigment to polymer coupling, two parts of thermally stable neoalkoxy titanates and zirconates per thousand parts of polymer provide for in situ metallocene-like repolymerization catalysis of the filled or unfilled polymer during the plastication phase resulting in: significantly faster blow molding production cycles at lower temperatures while maintaining or increasing mechanical properties; the in situ regeneration of regrind polymer to virgin properties; the lowering of polymer recrystallization time; and the copolymerization of dissimilar polymers.

Introduction
Previous papers1-10 by the author proposed that minor amounts of thermally stable neoalkoxy titanates and zirconates (cf. Ref. 10-Table 1) provide: a method for filler/pigment coupling (or bonding) at temperatures above 100°C in the thermoplastic melt phase via a proposed proton coordination mechanism, absent the need of water condensing mechanisms as with silanes, to a wide variety of substrates heretofore considered non-reactive with silanes; and for in-situ metallocene-like repolymerization catalysis of the filled or unfilled polymer during the compounding, extrusion and blow or injection molding plastication phase resulting in significantly faster production cycles at lower temperatures of thermoplastic parts having better finish and equal or better mechanical properties.

The effect is permanent and recyclable since the neoalkoxy titanate or zirconate ester remains permanently in the polymer as a repolymerization catalysis agent as opposed to Ziegler-Natta or metallocene (titanocene or zirconocene) derived polymers wherein the benefits are obtained when the monomer is only exposed to the mixed metal or biscyclodienyl derived titanium or zirconium complex catalyst during macromolecule formation (polymerization). For example, HDPE regrind from blow molding operations can be regenerated to virgin-like properties and PET regrind/PC regrind – 80/20 or LDPE regrind/PP regrind – 80/20 polyblended in a twin screw extruder will show significantly increased HDT, melt flow, tensile modulus and elongation using a neoalkoxy tridioctyl phosphato titanate (Ken-React® LICA® 12) or zirconate (Ken-React® NZ® 12) at 0.2% by weight of the polyblend against a control.

This paper is written as an updated review of References 1-10 and will discuss claimed performance benefits and application considerations.Discussion
The following claimed performance benefits for the thermoplastics blow molder and processor using subject neoalkoxy titanates and zirconates are based on 27 years of experience obtained through research and development, plant trials, customer and investigator reports (patents, published articles, technical papers and private communications). For example, a series of ACS CAS Searches for “Ti or Zr coupling agents” conducted from 1974 to July 31, 2000 provided abstracted results from 18 primary, non sub-divisional US Patents and 66 technical papers by the author and 1253 patents and 292 technical papers by others for the period. The Japanese dominate with 83% of the patents filed – many of which are U.S., EP or WO (World) based.

The 100% active liquid coupling agent titanate (LIquid Coupling Agent) or zirconate (NZ) may be added to a liquid color concentrate. The use of a 20% active pellet masterbatch of the liquid neoalkoxy tridioctyl phosphato titanate or zirconate in 20-melt LLDPE binder (CAPS® L12/L or CAPS NZ 12/L) added like a color concentrate pellet provides best results with blow mold operations using pellets or a 65% active powder masterbatch on 0.022 micron silica (CAPOW® L12/H or CAPOW NZ 12/H) is best suited for polymer powders.

Claimed Performance Benefits

1. Profit – Faster Cycles, less Energy – 1% CAPS L12/L on average will reduce injection and blow mold cycle times by 19% and process temperatures by 9% (cf. Ref. 10 Table 3). Up to 40% cycle time reductions have been achieved1-5. Typically, just a 4% cycle time reduction for a fully utilized production capital equipment setup pays the cost (US$8.5/kg.) of the additive and further reductions fall to the bottom line as profit (Ref. 10 – Table 4).

2. Quality – Stronger, Better Parts – Mechanical prop- erties and dimensional stability are maintained or improved because 0.2% Ken-React LICA 12 provides process rheology advantages by a claimed in situ metallocene-like catalysis mechanism which Kenrich has patented worldwide under the title of “Repolymerization” (U.S. 4,657,988)6. In the “Repolymerization” EP patent (European Patent Application No. 87301634.9-2109) peer reviewed by the EPO in Munich in November, 1996 and accepted in 1998, examples 6 to 16 showed the improved physical property effects of six neoalkoxy titanates (LICA’s 01, 09, 12, 38, 44 and 97) and six neoalkoxy zirconates (NZ’s 01, 09, 12, 38, 44 and 97) in powder form at 3 to 5 dosage levels in eleven thermoplastics (ABS, Acetal, Acrylic, CAB, Nylon 6, PC, PP, HDPE, PBT, PPO, and PS). The “best” titanate or zirconate and “optimum” dosage for each polymer were reported (cf. Ref.1-Fig. 4).

3. Use Less Plastic – Use less plastic to equivalent strengths – particularly in blow molded thermoplastics where outer dimensions are unaffected by thinner gauging. For example, a HDPE marine fuel tank produced by Flambeau Corporation, Baraboo, Wisconsin, USA uses 1% CAPS NZ 12/L to reduce cycle time from 186 to 116 seconds at lower process temperature while reducing part weight from 1745 grams to 1500 grams to equivalent drop weight impact strength (cf. Ref. 1 – Fig. 14). The strength tests consisted of 3+-meter drop-weight impact of water filled containers and two-year Florida Everglades UV exposure of fuel filled containers.Table 1 shows that 0.2% NZ 12, when added via a liquid color concentrate, had the following effects on a blue blow molded HDPE toy wheel:

Reduce part weight to equal strength from 125-135 to 100-105 grams.
Increased regrind to virgin ratio from 50:50 to 80:20.
Reduced Cycle Time from 50.6 to 41.1 seconds.
Reduced temperature of the process melt from 361 to 332 ° F (183 to 166 ° C).

4. Process Engineering Plastics like Commodity Plastics – Diamond Machinery Technology Inc., Marlborough, MA. injection molds whetstones for knife sharpening using 40% fiberglass reinforced polycarbonate as a base (cf. Ref. 1 – Fig. 11), which they buy as already formulated from a custom compounder. Stanley A. Watson, Electroplating Manager/Chemist stated in a letter dated May 16, 1994 (cf. Ref. 1 – Fig. 10): “We have, as your Reference Manual indicates, experienced a significant decrease in barrel temperatures from as high as 580°F without coupling agent to as low as 370°F with agent. Our initial tests (with 1% CAPS L12/L) had such drastically altered rheology that most of our testing involved an attempt to regain prior flows and characteristics.”

5. Virgin-like Recycled or Regrind Parts – “In situ metallocene-like catalysis” or “repolymerization” catalysis regenerates recycled and regrind thermoplastics to virgin or better properties. A previous paper7 on recycled plastics offered significant thermoplastic processing benefits for regrind and three examples were reviewed (cf. Ref. 7 – Tables 10, 12, 13 and Figs. 11 and 13).

6. In-Situ Copolymerization, Alloying or Compat– ilbilization of Polyblends – Thermally stable neopositioned quaternary carbon based (neoalkoxy) organometallic esters allow for “copolymerization” or “alloying” or “compatibilization” of dissimilar plastics such as PET and PC blends. For example, 0.2% LICA 12 in a recycled PET/recycled PC – 80/20 blend provided a ten-fold increase in elongation and doubling of tensile modulus over a control blend8. A slide will be shown at ANTEC 2001 of the improvement in the appearance of a LLDPE regrind/PP regrind – 80/20 using CAPS L12/L.

7. Synergize Blowing Agent Performance – Endothermic and exothermic blowing agents are made significantly more efficient to produce lighter polymers with more uniform cell structure because, among other effects, titanates and zirconates at the elevated temperature where gas generation (blow) occurs maintain or increase polymer bubble stress (force/area) properties while strain (elongation/unit length) properties are doubled or tripled. Thus, polymer bubbles do not break because of the greater stress/strain strength resulting in smaller and more uniform cell structure. Since the effect is based on polymer morphology, the source of gas or blow can be diverse such as butane, endothermic or exothermic chemical blowing agents or even RDX [cf. “High Energy Plastic Explosive” (ES 2067367) and “Insensitive Explosive Composition” (US 5472531)].Other examples have been provided: Cell size variation is reduced from 6 – 48 micron to 9 -15 micron in an exothermic azodicarbonamide foamed PE (cf. JP 58 75,713 Showa Denka Kk, Ref. 2 – pgs. 60 to 62 and Ref. 7 – Fig. 17); the density of an azodicarbonamide foamed flexible PVC is decreased threefold from 0.408g/cc to 0.129g/cc (cf. Ref. 4 – Fig. 3); the amount of endothermic sodium bicarbonate needed to foam SBR (Styrene Butadiene Rubber) is reduced twenty-nine fold from 15 phr of NaHCO3 powder to 0.68 phr of a 75% active NaHCO3 paste masterbatch containing pyrophosphato titanate in the aromatic plasticizer phase (cf. Ref. 9 – Fig. 14).

Some practical foamed applications reported are: added dimensional stability to 100% regrind MDPE extrusion profiles; increased filler loads while not increasing density of recycled HDPE extruded lumber boards; injection molded CaCO3 filled PP coat hangers having excellent memory (return to original shape); injection molded crates having low specific gravity and excellent strength (cf. Ref. 7 – Pg. 13).

8. Brighter, Better Aging Composites and Colors and Reduced Pigment Plateout – Monomolecular layer of an organometallic titanate or zirconate makes inorganic and organic pigments and fillers hydrophobic and organophilic (cf. Ref. 2 – Pgs. 2, 3, 41 to 44) and eliminates air and water at the pigment/polymer interface resulting in benefits such as increased adhesion10, reduced plate-out of fluorescent colors 11 and better aging of filled and fiber reinforced polymers12.

For example, investigators from Osaka University concluded11: “The effects of different coupling agents on the mechanical properties of the TiO2 coated with a silane coupling agent were compared with composites prepared by dispersing titanate coupling agent-coated TiO2 in epoxy, Young’s modulus and flexural strength of the titanate coupling agent-treated composites were significantly better than those of the silane coupling agent-treated composites. Apparently a strong interfacial bonding between the filler and the matrix existed when the titanate coupling agent was used.”

In blow molded HDPE tests, a fluorescent pigment manufacturer concluded12: “Most efficient reactive additives were the Ken-React liquid and its powder grade equivalent. Other reactive additives effectively reduced plateout, but also caused brightness loss or flow molding problems.”9. Functionalize Pigments and Fillers – Coupling permits much higher loadings (cf. Ref. 2 – Fig. 126) and converts the filler to a catalyst support bed for reaction with the organic phase13 to create a true continuous inorganic/organic matrix14 for possible applications such as:
Magnetic plastics or EMI/RFI shielding – Magnetic gamma ferric oxide loadings may be increased with significantly enhanced performance15 and typically metal oxides and pigments dispersed in polymers exhibit decreased resistivity, i.e. 1010 (control) to 105 (titanate) ohm-cm for a 60% loading of a ZnO-Al2O3 mixture in PP16.

Non-toxic Flame Retardance – Phosphato and pyrophosphato functionality provides phosphato and pyrophosphato intumescent synergism and high loadings of non-toxic ATH2 or Mg(OH)217. Typically, greater than 60% ATH loading by weight is needed in PP to obtain a UL94 Vo rating. For example, Robert Andy stated in U.S. 4,525,494: “The present invention provides a polypropylene composition containing (64%) hydrated alumina which has high izod impact strength, increased flow, increased elongation, increased deflection and increased Gardner impact values compared with the original polypropylene, with loss of tensile strength. The practice of this invention will give flame retardance to any polypropylene system while enhancing the strength of the product. For example, the practice of this invention has produced polypropylene products that have impact strengths which are increased four times and flow rates increased seven times over the starting material without loss of tensile or any other critical property”. Note the Alcoa hydrated alumina, Lubral® (isostearic acid) coated particulate exhibited improved mechanical properties only after in-situ reaction with the phosphato titanate.

Impart “microwavability” or “X-ray detectability” to plastics due to high levels of BaSO4. For example, 70% BaSO4 filled PP fibers used as postoperative x-ray detectors in cotton swabs can be produced on a spinneret under virgin, unfilled PP conditions (Ref. 2 – Fig. 172).

Couple or bond dissimilar substrates such as carbon fibre to PE18 to make light but strong thermoplastics or make 18% pyrophosphato titanate treated conductive carbon black in LDPE provide the same PTC (Positive Temperature Coefficient) as 25% carbon black without coupling agent 19.

10. Transparent, Permanent, Non-Blooming and Non-Moisture Dependent Anti-Static Plastic – Combined dissimilar thermally stable trineoalkoxy organometallic zirconates (Ken-Stat® KS MZ100) may be dispersed atomically into the polymer to form bipolar electrostatic dissipative layers, which conduct electrons volumetrically through as well as along the polymer surface, to create antistatic parts and sheets that are transparent, permanent, non-blooming and non-moisture dependent20.

The foregoing are some of the claimed performance benefits of subject organometallic titanates and zirconates. Published efforts in metallocene (titanocene and zirconocene) chemistry by major polymer producers appear to be centered around olefin polymers and copolymers. Effects of neoalkoxy titanates and zirconates on metallocene derived polyolefins are incompletely determined. Catalysis effects of subject additives often vary type and amount on filler as well as polymer. For example, 1.6% LICA 38 outperforms 0.5% LICA 12 or KR TTS in wollastonite filled PP because of catalysis/mechanical property effects. Luo reported 18 work under the direction of noted rheologist Dr. Paul Han which showed at shear stresses above 200N/m2 for 50% CaSiO3 filled Nylon 6 that 1% amino titanate (KR 44) treated filler containing composites exhibited melt viscosity at 230°C lower than pure Nylon 6 and that an amino silane (A-1100) had a similar but lesser effect. The same effect on rheology was not noted for titanates or silanes when CaCO3 was substituted for CaSiO3.

In any case, the titanocene or zirconocene catalysts used in synthesis do not remain in the polymer, as do the titanate or zirconate ester forms, to “anneal” polymer chain lengths “scissored” during processing. Also, metallocene derived HDPE and engineering plastics appear to be still off in the future while the titanate and zirconate esters appear to be efficacious to some degree in virtually all polymers synthesized via various routes.

Application Considerations

Two principles govern the applications art of coupling agents: uniform distribution before the polymer melt phase and high specific energy input for maximum dispersive work energy during the polymer melt phase.

Uniform Distribution Before the Polymer Melt Phase – Subject organometallics work on a stoichiometric catalytic principle and must be dispersed as thoroughly as possible throughout the unmelted polymer composite materials before the onset of melting whereupon catalysis is initiated as the titanate or zirconate solvates into the polymer organic phase. The pellet (CAPS) form is the simplest and best for the typical injection, blow molding or extrusion molding set-up. The liquid and powder forms of the coupling agent may also be used so long as there is no localization caused by poor mixing techniques, which create polymer or filler surface physiabsorption of the additive.

Specific Energy Input During the Polymer Melt Phase – Once the polymer begins to melt, work energy through mechanical shear creates the required intimate polymer/catalyst (coupling agent) mixing. The area under the power curve formed by a plot of torque vs. time is a measurement of the work energy or shear on the polymer/catalyst matrix. The most efficient polymer mix cycles generate peak torque in a short time. Torque is controlled by temperature, rpm’s and back pressure. High torque creates high polymer shear rates. Polymers are non-Newtonian in flow and their melt viscosity decreases asymptotically with increasing shear. Under high shear rates, polymers exhibit the lowest viscosity with the least amount of variation as compared to greater polymer viscosity variation at lower shear rates – i.e. high shear rates give reproducible results. Most polymers (except for heat sensitive PVC) are not damaged by higher shear. Low shear rate melt indexers are not the way to measure the effect of subject additives. Lowering the polymer processing temperature is usually the most direct way to maintain shear and torque for efficient blow molding.

Conclusion

This paper claims ten significant benefits for compounding, extruding or injection and blow molding with subject additives. Some applications considerations were discussed.

References

1. Monte, S.J., “Injection Molding with Neoalkoxy

Titanates and Zirconates”, SPE/RETEC Conf. “Polymer Additives for Injection Molding and Extrusion Appli-cations”, Whitehaven, PA, USA, October 19, 1995.

2. Monte, S.J., Kenrich Petrochemicals, Inc., “Ken-React® Reference Manual – Titanate, Zirconate and Aluminate Coupling Agents”, Third Revised Edition, March, 1995.

3. Monte, S.J., “Increased Productivity of Thermo-plastics Using Organometallic Titanate and Zirconate Coupling Agents”, SPE ANTEC, New York, May 1-3, 1989.

4. Monte, S.J., “Coupling Agents Increase PVC

Productivity”, Plastics Compounding Magazine,

November/December 1989.

6. Kenrich Petrochemicals, Inc., U.S. 4,657,988 -4/14/87.

7. Monte, S.J., “New Opportunities in Recycled

Plastics With Neoalkoxy, Titanate and Zirconate

Coupling Agents”, SPE Recycle RETEC, October

31,1989, Charlotte, NC.

8. Monte, S.J., “Titanium and Zirconium Esters as

Couplers and Single Site Catalysts for In-Situ Repoly-merization and Copolymerization Useful for Recycled Polymeric Compositions”, Paper #57, ACS Rubber Division, Louisville, KY, October 8-11, 1996.

9. Monte, S.J., “More Efficient Manufacture of

Better Foamed, Filled and Unfilled Polymer Compounds With Titanate and Zirconate Coupling Agents (26 pgs., 44 Tables, 69 Figures)”, Northeast Regional Rubber & Plastics Exposition, September 21-22, 1994, Mahwah, NJ.

10. Monte, S.J., “Compound With Neoalkoxy

Titanates and Zirconates”, SPE/RETC, Montreal.

11. The Institute of Scientific and Industrial Research, Osaka University, “Effects of coupling agents on the mechanical properties improvement of the TiO2 reinforced epoxy system”, Mater. Lett. (1996), 26(6), 299-303 Coden:MLETDJ; ISSN:0167-577X.

12. Technical Bulletin No. 27, “Additives to Reduce Plateout of Day-Glo® zx-Series Pigments”, Day Glo Color Corp., subsidiary of Nalco Chemical Company.

13. Monte, S.J., “Better Bonding and Metallocene-like Catalysis Benefits for Elastomers”, Rubber

Technology International ’96, UK & International

Press, a division of Auto Intermediates Ltd.

14. E. White, “Additives Give Better Bonding”,

Reinforced Plastics June 1996, 0034-3617/96

Elsevier Science Ltd.

15. Fuji Photo Film Co., LTD., US 4,444,850.

16. Ajinomoto, JP 63268767 – 11/7/88

17. Mitsubishi Cable Ind., US 4,769,179 – 9/6/88.

18. Yeh, J.T.; Chen, B.J.; Lee, H.M. “Impact properties of Carbon Fibre Reinforced Liners & Short-Chain Branched Polyethylenes”, Polymer Bulletin 33 (Springer-Verlag, (607-614 (1994), National Taiwan Institute.

19. Yu, G., Zhang, M.Q., Zeng, H.M., “Carbon-Black-Filled Polyolefine as a Positive Temperature Coefficient Material: Effect of Composition, Processing, and Filler Treatment”, Journal of Applied Polymer Science, Vol. 70, 559-566 (1998).

20. US Patent 5,659,058, “Thermally Stable Antistatic Agents,” Monte, S.J dated August 19, 1997.