Joumal of Intellectual Property Rights Vol 4 September 1999 pp 286-292
Patent Literature on Catalysts for Olefin Polymerization: [I] Ziegler-Natta Catalysts
Anand Kumar KuIshreshtha & Santosh Kumar Awasthi
Research Centre, Indian Petrochemicals Corporation Ltd, Vadodara 391 346
Patents can make or break profits resulting from an invention, depending upon an organization's capability to protect its intellectual property rights from litigation by rivals. This paper chronicles the history of patents on olefin polymerization catalysts (rom 1950s to 1990s. Part 1 of the paper discusses in detail the patents ofZiegler-Natta Catalysts. It has been established by patent g ranting agencies that Karl Ziegler was the pioneer in inventing Ziegler catalysts in 1953. Giulio Natta who visited Ziegler's lab and became aware of his research around that time, afterwards became to be known as a co-inventor. Soon after, parallel patent applications were filed in 50 countries. Corporates [ought battles to destroy the patents position of Ziegler but did not succeed.
Ziegler-Natta polyolefin polymerization catalysts 1 are actually Ziegler catalysts. On 17 November 1953 Karl Ziegler filed the first patent application in Germany on this subject which was followed by a number of furth e r applications in 1954 . These applications were directed to the polymerization of a-olefins at normal or low pressure and a temperature up to 150°C in a hydrocarbon medium into high-molecular weight, solid and partly or high crystalline polymers.
After the first application in Germany, parallel applications in 50 countries were filed . Strong opposition was of course 'faced in industrialized countries like Germany, USA and Japan having sophisticated patent procedures. The German chemical companies
BASF, Bayer and Hoechst AG, the British ICI and Shell, and in the US, specifically Du Pont, Phill ips and Montecatini tried with all means available to destroy the patent position of Ziegler et at..
Standard Oil of Indiana and Phillips P troleum independently found in 1950-1952 from research programmes involving alkylating hydrocarbons with ethylene or oligomerizing olefins that solid high polymers as byproducts were formed when using certain transition metal oxides on silica-alumina carriers.
The yields obtained were measured in milligrams of polymer and efforts to develop fu rther the synthesis of these by-products did not proceed at that time. Thirty years later
KULSHRESHTHA&AWASTHI: PATENTLITERARTURE ON CATALYSTS 287
Table I-Early discoveries of low pressure linear polyethylene
Research groups Catalysts Time of initial Early polymer discovery density (g/cm:l)
Alex Zlet Standard Oil of Indiana
Nickel oxide activated Early 1950 0.96 carbon
Molybdenum oxide on alumina
J Paul Hogan and Robert L Banks, Phillips Petroleum Co.
Chromium oxide on silica 1951 0.95-0.97 alumina
Karl Ziegler et at. TiCl4
Max Planck Institute for Coal Research
a court in Wilmington, Delaware, decided that Hogan and Banks of Phillips Petroleum (Table 1) were first party to have these propylene polymers in their hands.
It is pretty clear that the properties of these first propylene polymers are very different from any co mm erc ia ll y produ ced polypropylene products today. Furthermore, the catalysts developed by these two American research teams were never used for the co mm erc ial production of polypropylene. Indeed in 1973 both companies took a Ziegler licence.
During the inventive phase in 1953, Italian and American chemists visited the Institute for a period of several months. (From Montecatini/G. Natta, Italy: Paolo Chini, Roberto Magri, Giovanni Crespi; from Hercules Powder Co., USA Arthur Glasebrook). The Italian gentlemen were sent to the Institute under an earlier agreement between Montecatini and Ziegler, covering a research area of pure organo-aluminum chemistry. These visitors could not be kept away from information concerning the discovery of the new catalysts. At the end of 1953 and January 1954, Ziegler fully infonned a co-worker of
+R1Al Late 1953
Natta and Montecatini of the nature of the new catalysts. Natta et al. used the info rmation of Ziegler to polymerize propylene before Ziegler and Martin and filed patents in Italy on the subject all without informing Ziegler, although there was a written agreement reserving for Ziegler further research on developing the catalysts and their use for polymerization of olefins. It was a cause of irritation and conflict between the parties.
As expected, Ziegler's and Natta's basic patents very soon became involved in an interference procedure in USA, since both parties claimed the polymerization of propylene using identical catalysts. In 1969 the US Patent Office awarded priority to Ziegler.
Du Pont fought for almost ten years up to 1964, against Ziegler's applications. They took a licence, but tried to trade the price down as far as possible.
Another effort by Du Pont was to get Karl Ziegler to define the term "aluminum trialkyl" as used in the definition as Ziegler catalysts,' so as to award what Du Pont was doing.
288 J INTELLEC PROP RIGHTS, SEPTEMBER 1999
In 1967 Phillips Petroleum opened a commercial plant in the US for the production of polypropylene using a catalyst produced from EtzAlCI and a-TiCh.1/3 AlCh. It took six years for an appeal court in Houston to decide that the Ziegler et at. patent involved comes under the definition of a pioneer patent covering a function never before performed. As a consequence th e court decided that the catalyst used by Phillips was a Ziegler catalyst and was covered by the Ziegler pioneer patent.
When arguing with the patent examiner in Washington during prosecution over one of the basic Ziegler patents in 1955 the examiner took the position that producing the catalyst on one side and using the catalyst producing polyolefins on the other side are two separate inventions, since the catalyst can be used for applications other than polymerizing a-olefins. As a consequence he requested division of the application into two parts.
The first part, the catalyst claims, was accepted and the patent issued in 1963, ten years after the invention. The use of this catalyst in a process to polymerize a-olefins was accepted and patented in 1978. Since the American patent law provides a 17 years' protection from the issue of the patent the first patent expired in 1980, but the second patent has expired in 1995.
Ziegler catalysts are wondetiul. A variety of applications are listed in Table 2.
Patents on Conventional Titanium-Aluminum Alkyl Catalysts2
Initially the use of titanium-aluminum alkyl catalysts to 'produce polyethylene grew at a much slower pace than the chromium oxide on silio catalysts. The main difficulty with
the original catalysts was that the yield of polymer per unit of catalysts in low pressure processes was so low that the catalyst residuals in the polymer had to be extracted. Not only were titanium residuals high but chloride levels were correspondingly high, resulting in severe corrosion problems in addition to the colour and stability problems caused by the metal residuals. Since chromium oxide catalysts were high in activity (200-600 kg of polymer per gram of Cr metal) and contained no chloride, no catalyst residual removal steps were required. Thus, the cost of operating a titanium-aluminum alkyl process exceeded that of operating a Phillips process. Yet, the market demand for a low molecular weight, narrow WD resin was sufficient to spur research.
Here is a good example of how catalyst, process, and market interact. In the early 1970s the Phillips slurry process with Phillips catalyst was less costly and easier to operate. However, some products demanded by the marketplace could not be efficiently produced. So without promise of success, research on the titanium-aluminum alkyl catalysts to improve activities continued at a rapid pace. In the end these efforts were very successful, and the marketplace today is supplied with the sought-after ti tanium-aluminum alkyl resin from processes (slurry, solution, and gas phase), which are much more economical than the earlier versions.
Table 2 shows some of the initial work on supported early transition metal catalysts. Although the patented processes represented here did not accomplish the goal of eliminating catalysts removal process steps, they did point the direction and provide the needed incentive to continue the efforts_ It is worth noting how early the supported work began (in 1955). The first supports
KULSHRESHTHA & AWASTHI : PATENTLITERARTURE ON CATALYSTS 289
Table 2 - Polymerization with Ziegler-Catalysts
Polymers Monomers Calalyst
-CH2-CH2- CH2-CH2- (l inear) Ethylene Et2AICI + TiCI4
R R R I I I
- CH2-C-CH2-C-CH2-C-higher et -olefins
AIEt3+ VCI3 I I I Et2AICI + TiCI3 H H H
R = CHJ, C2HS etc_
y H3 H y H3 I -CHcy~CH2-y-CHz-y- Propylene EI2AICI + VCI4
H CH3 H
optically active polym er ,
3-Phenyl-butene-( 1) ElzAICI + TiCIJ
yHJ y H3 EtzAICI + EtAIClz -y-CH2-CH2-CH2-
y- CH2- Ethylene + Propylene
+ VOCIJ H H
Terpolymers Ethylene + Propylene Et2AICI I EtAICI2 I + Diene VOCI3
-(CH2h-CH=CH-CH2- + - CH2-CH-
~ , Vinylcyclopropane Et2AICI + VCI3
-CHz-Q- -CHz-yH-
(yH2lz Biallyl AliBu3 + TiCI4
CH - CH2
-C~2 ,CH2- Et2AICI + CoClz C=C .cis - 1,4 Butadiene EI2AIJ + TiCI4 H H
-C~2 H C= C trans - 1,4 Butadiene AIEtJ + VCI3 H "-CHz-
- CH2-yH-
AIEt3 + Ti(OBu)4
CH 1,2 - Buladiene " AIEI3 + Cr(acb I CH2
- Ctl2 /H2-
C~C cis-l.'l-lsoprene AliBuJ + TiCI4 / H
CHJ
Cyclododecatriene-1,5,9 trans, trans, cis Buladiene EI2AICI + TiCI4
Polypentenamer cis Cyclopentenc AIEIJ + MoCls
Polypentenamer trans Cyclopentenc AIEtJ + WCI6
290 J INTELLEC PROP RIGHTS, SEPTEMBER 1999
were metal oxides (perhaps an imitation of chromium oxide successes), halides, and carbonates.
proach with transition metals attachecl to surface hydroxy species, other group~. were finding that the transition metal did not have to be anchored to the support for high activities. Many of these catalysts (Table 4) consisted of magnesium alkoxides reacted with transition metal halides. During the preparation, the original sb-ucture of the magnesium alkoxide is completely desb-oyed and a new species formed, perhaps with an increase in surface area. These catalysts could be further modified by introduction of additional compounds into the cataly.tic complexes such as complex magnesium alkoxides (e.g., Liz[Mg(OCzHs)4]) or by carryi~g out the reactions in th~ presence of an acid hal-
In the mid-1960s the work on these transition metal supported systems really began to reach fruition . Poss ibly stimulated by Cabot's 1960 patent (BP 969, 761), Solvay, Hoechst, Mitsui, Montecatini, and B.F. Goodrich came out with a series of patents dealing with supporting halotitanium species on hydroxymagnesium halides (Table 3). The degree of dehydration of the support, just as with chromium-silica catalysts, played a significant rol e in their activities.
While the researchers just mentioned were studying the classic supported catalyst ap-
Patent No.
BP 841,822
US 3, 153 634,
US 2,980,662
US 2,980,662
BP 877,457
BP 969,761
BP 969,767
Table 3- Early supported catalysts
Date
1955
1956
1956
1956
1957
1960
1963
Company Catalyst preparation
British TiCl4 reduced by aluminum alkyls Petrochemicals in the presence of solids such as
MgCO;l.
Sun Oil TiCl4 was adsorbed on Si02 / AlZO;l and reduced
Sun Oil Ti compounds reduced in the presence of solid NaCI, FeCh. AlCh, GaCh
Sun Oil Ti compounds reduced in the presence of sol id , NaCI, FeCh"AlCh, GaCh etc.
Sun Oil TiCl4 reduced in the presence of inorganic compounds.
Cabot Transition metal compounds reduced in the presence of SiOz, AlZO;l, SiOz/ AlZO;l, ZrOz, TiOz, ThO, MgO, etc.
Cabot Transition metal compounds reduced in the presence of Si02, AlZO;l, ZrOz, TiOz: 1110, MgO, etc.
KULSHRESHTHA& AWASTHI : PATENTLITERAIITURE ON CATALYSTS 291
Table 4 - Magnesium hydroxychloride supported catalysts
Patent No. Date Company Catalyst preparation
BP 1,024,336 1963 Solvay Reaction of a transition metal with a hydraxychloride of a bivalent metal, preferably Mg(OH)CI.
JP45-40295 1967 Mitsui TiCI4 reacted with Mg(OH)2 and reduced
US 3,634,384 1968 BFGoodrich TiCI4 reacted with Mg(OH)z and reduced
BE 726,839 1968 Solvay Reaction of magnesium hydroxid e with a transition metal halide
BE 728,002 1968 Montecatini
BE 735,291 1968 Hoechst
Table 5 - Magnesium alkoxide-based catalysts
Patent No. Date Company
US 3,644,318 1968 Hoechst
BE 758,994 1969 Hoechst
BE 743,325 1969 Solvay
BE 780,530 1971 Hoechst
NL216,195 1971 Solvay
ide (e.g., SiCI4 or BCI3). By the end of the 1960s, there was a good deal of interest in this new type of catalyst, which no longer required expensive deashing s teps.
Gradually evolving from all this titanium-aluminum alkyl catalyst research were even high er activity catalysts. These supported approaches eventually led to the catalyst sys-
Catalyst preparation
TiCI4 reacted with Mg(OR) 2 or a complex magnesium alkoxide
Reaction of magnesium alkoxid e and an acid halide with a tetravalent titanium compound
tems consisting of MgCI2 ball-milled with TiCk
!twas reasonable to try to combine the newly ball-milled MgCIz.Mg(fiCI6» catalyst with alkoxides similar to those used for the Mg(OR) 2. TiCI4 system. The results by the early 1970s were yet another boost in catalyst activity, which was at this point high enough to eliminate all deashing steps (Tables 5 and 6).
292 J INTELLEC PROP RIGHTS, SEPTEMBER 1999
Table 6- Magnesium chloride based catalysts
Patent No. Date Company
BP 1,286,867 1968 Montecatini
BE 744,221 1969 Montecatini
BE 747,846 1969 Montecatini
JP 46-34092 1968 Mitsui
U.S. 3,642,746 1968 Mitsui
JP 46-34093 1968 Mitsui
BE 755,185 1969 Hoechst
References
1 Martin H, Ziegler Catalysts (Springer Verlag, New York 1995) .
Cat.alyst preparation
TiCl4 ball-milled with MgCl2
Reaction of MgCl2 with halogenated titanium compounds
TiCl4 reacted with MgCI2. nROH MgC12.nH20 or MgCl2.Lewis base
Reaction of a magnesium dihalide electron donor adduct (e.g., MgCI2. 6C2HsOH) with a titanium compound
2 Welch M B & Hsiech H L, Olefi n polymerization catalyst technology, Eur Pat EP 685, 495, 6 Dec 1995.
Top Related