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United States Patent m
Hoff et al.
 POLYMERIZATION CATALYST AND METHOD
 Inventors: Raymond E. Hoff, West Chester, Ohio; Leonard V. Cribbs, Houston, Tex.
 Assignee: Quantum Chemical Corporation,
New York, N.Y.  Appl. No.: 822,440 22] Filed: Jan. 17,1992
51] IntCl.5 C08F4/02
52] US. CI 502/111; 502/104;
502/115; 502/117; 502/125; 502/126; 526/142;
 Field of Search 526/142, 904; 502/104,
502/111, 115, 117, 125, 126, 133, 134  References Cited
U.S. PATENT DOCUMENTS
2,981,725 4/1961 Luft et al .". 260/93.7
3,121,658 2/1964 Orsino et al 162/146
3,297,466 1/1967 Herman et al 117/47
3,503,785 3/1970 Knise 117/62.2
3,654,249 4/1972 Diedrich et al 260/88.2
3,759,884 9/1973 Tokuzumi et al 260/88.2
3,876,602 4/1975 Calvert et al 260/94.9 P
3,926,717 12/1975 Marchessault et al 162/157 C
4,012,342 3/1977 Dougherty 525/426
4,021,599 5/1977 Kochhar et al .'. 526/124
4,039,472 8/1977 Hoff 252/429 C
4,082,692 4/1978 Goldie 252/429 B
4,097,409 6/1978 Speakman 252/429 R
4,329,255 5/1982 Beach et al 252/429 B
4,359,403 11/1982 Hoffetal 252/429 B
4,374,753 2/19831- Pullukat et al 252/429 B
4,431,788 2/1984 Kaminsky 526/142
4,530,913 7/1985 Pullukat et al 502/104
4,532,311 7/1985 Fulks et al 526/62
4,792,592 12/1988 Fulks et al 526/62
4,792,640 12/1988 Mehta 568/851
4,803,251 2/1989 Goode et al 526/59
5,045,612 9/1991 Schell, Jr. et al 526/142
5,051,484 9/1991 Sasaki et al 526/904
FOREIGN PATENT DOCUMENTS 834217 5/1960 United Kingdom .
W. Kaminsky, "Polymerization and Co polymerization with a Highly Active, Soluble Ziegler-Natta Catalyst",
[li] Patent Number: 5,198,399  Date of Patent: Mar. 30, 1993
Transition Metal Catalyzed Polymerization, Alkenes and Dienes, Part A, R. P. Quirk, et al., eds., Harwood Academic Publishers, pp. 225-244 (1981). H. D. Chanzy, "Transition-Metal Catalysts for Polyethylene Encapsulation of Substrates", Ph.D. Thesis, Syracuse University (1966).
A. Dankovics et al., "Kinetic Studies on the Cellulose— Propylene System in Presence of Ziegler-Natta Catalysts", J. Appl Poly. ScL, vol. 13, pp. 1809-1824 (1969). T. Heinze, et al., "Spharische ionotrope Gele carboxygruppenhaltiger Cellulose-derivate als Tragermaterialien fur biologische Wirkstoffe, I" Agnew, Macromolecular Chem., 169, p. 69 (1989) (including an English language summary).
Primary Examiner—Joseph L. Schofer
Assistant Examiner—David Wu
Attorney, Agent, or Firm—Marshall, O'Toole, Gerstein,
Murray & Bicknell
A catalyst, a method of preparing the catalyst, and a method of using the catalyst with a suitable cocatlayst in the polymerization or copolymerization of 1-olefins are disclosed. The catalyst is prepared by: a) contacting a group IIA organometallic compound, like 2-methylpentanoxymagnesium chloride, or a Group III organometallic compound, like triethylaluminum, or a combination thereof, with a porous or nonporous biodegradable substrate having active surface hydroxyl groups, like cellulose, to provide a modified biodegradable substrate; then b) contacting the modified biodegradable substrate with a transition metal compound, such as a transition metal halide or alkoxide, like titanium tetrachloride or vanadium(V)trichloride oxide, to form discrete catalyst particles. The catalyst particles are used in conjunction with a suitable cocatlalyst, like triethylaluminum, in the homopolymerization or copolymerization of 1-olefins. During polymerization, porous biodegradable catalyst particles are fragmented into small solid particles that are trapped within polymer. The fragmented catalyst particles are allowed to remain within the polymer; do not adversely affect the physical or esthetic properties of the polymer or articles made therefrom; and serve as biodegradable sites that facilitate environmental degradation of the polymer.
39 Claims, 1 Drawing Sheet
POLYMERIZATION CATALYST AND METHOD
HELD OF THE INVENTION
This invention relates to an olefin polymerization 5 catalyst, a method of making the catalyst, and a method of polymerizing one or more 1-olefms utilizing the catalyst with a cocatalyst. More particularly, the invention relates to a Ziegler-type catalyst useful in polymerizing one or more 1-olefins, wherein the catalyst is prepared 10 by first contacting a Group IIA or Group III organometallic compound with a biodegradable substrate having surface hydroxyl groups (e.g., cellulose) to provide a modified biodegradable substrate. The modified biodegradable substrate then is contacted with a hydrocar- 15 bon solution of a transition metal, such as titanium, vanadium, or zirconium, to provide a catalyst. Optionally, a portion of the hydroxyl groups of the biodegradable substrate can be modified by silylation or fluoridation prior to the modification of the remaining hydroxyl 20 groups of the biodegradable substrate with the Group IIA or Group III organometallic compound. The inventive catalyst is a solid compound, and is used in conjunction with a cocatalyst to effectively catalyze polymerization of 1-olefins. Catalyst particles trapped 25 in the polymer product can remain in the polymer and do not adversely affect the physical or esthetic properties of the polymer or articles made therefrom. In addition, the trapped catalyst particles within the polymer serve as biodegradable sites that facilitate environmen- 30 tal degradation of the polymer.
BACKGROUND OF THE INVENTION
Ziegler discovered a two component catalyst for the polymerization of olefins. The catalyst included a com- 35 pound of the group IVB-VIB metals of the periodic table and an organometallic compound belonging to Groups I-IIIA of the periodic table. The traditional Ziegler catalysts efficiently promoted the polymerization and copolymerization of olefins to provide high 40 yields of polyolefins that possess the properties desired for practical applications. However, although Ziegler catalysts have been widely utilized, conventional Ziegler catalysts demonstrate important disadvantages. Researchers have discovered numerous Ziegler-type cata- 45 lysts that demonstrated improvements over the traditional Ziegler catalysts. The improved Ziegler-type catalysts have been employed for many years in the production of polyolefins. However, these new catalysts had relatively low activity and stability. Thus, 50 because disadvantages in Ziegler-type catalysts still exist, improvements in Ziegler-type catalysts for polymerizing one or more 1-olefins are continually being sought.
Researchers especially have attempted to provide 55 catalysts demonstrating a higher activity and a high stereospecificity. In particular, so-called "supported catalysts", such as titanium supported on a suitable carrier, have been developed. For example, U.S. Pat. No. 2,981,725 discloses a process wherein the catalyst 60 components were deposited on an inert support such as magnesium chloride, silicon carbide, silica gel, calcium chloride or a similar compound. However, the activity of the resulting catalyst is still low. In addition, several catalysts have been disclosed wherein a titanium halide 65 or a vanadium halide is reacted with a magnesium-containing support, such as a magnesium alkoxide or magnesium hydroxy chloride. U.S. Pat. Nos. 3,654,249;
3,759,884; 4,039,472; 4,082,692; and 4,097,409 describe such catalysts. These supported catalysts greatly increased the ability of the titanium to polymerize a 1-olefin compared to a traditional Ziegler catalyst.
Research has been directed to making improved supported catalysts. Numerous patents disclose catalysts supported on silica or alumina. Porous silica and alumina supports for high-reactivity catalysts were found to fracture during polymerization reactions. The residual, fractured particles of catalyst in the polyolefins were sufficiently small such that the particles did not adversely affect the polyolefins. In contrast, nonporous silica and alumina catalyst supports do not fracture during polymerization reactions. Therefore, the residual nonporous catalyst particles embedded in the polyolefin resins were sufficiently large to cause bubble tearing in blown film line operations; defects and gels in thin films; and clogged filters in extruders.
Other support materials for Ziegler-type catalysts have been sought. For example, U.S. Pat. Nos. 3,297,466 and 3,503,785 disclose that solid particles, such as cellulose, carbon black, wool, silk, asbestos, glass fibers, metals, oxides and synthetic fibers, can be encapsulated by polymerizing an olefin on a solid particle surface having a polymerization catalyst incorporated therein. U.S. Pat. No. 3,121,658 discloses treating cellulose fibers with a two-component Ziegler catalyst to catalyze the polymerization of ethylene or propylene on the fiber, and therefore encapsulate the cellulose fiber. Marchessault et al., in U.S. Pat. No. 3,926,717, disclose forming a Ziegler-type catalyst throughout a formed cellulosic substrate. An olefin then is polymerized throughout the cellulosic substrate to improve the water resistance and heat-sealing properties of the substrate.
Other patents and publications also disclosed forming a Ziegler-type catalyst on a cellulosic substrate. For example, Kaminsky, in "Polymerization and Copolymerization with a Highly Active, Soluble Ziegler-Natta Catalyst", Transition Metal Catalyzed Polymerization, Alkenes and Dienes, Part A, R. P. Quirk, et al., eds., Harwood Academic Publishers, pp. 225-244 (1981), discloses coating a surface of a cellulosic substrate with a polymer by attaching a catalyst to the surface of the substrate, then polymerizing ethylene on the substrate surface. Other patents and publications that disclose the use of a cellulosic substrate for a Ziegler-type catalyst include:
H. D. Chanzy, "Transition Metal Catalysts for Polyethylene Encapsulation of Substrates", Ph.D. Thesis, Syracuse University (1966);
A. Dankovics et al., /. AppL Poly. ScL, Vol. 13, pp. 1809-1824 (1969), wherein a Ziegler-Natta catalyst is adsorbed onto a cellulose surface, and a subsequent polymerization of propylene on the surface encapsulates the cellulose, the encapsulated cellulose and untreated cellulose then are combined to form a pulp to make paper;
Dougherty, U.S. Pat. No. 4,012,342, discloses the low pressure polymerization of olefins on the surface of organic fibers including a catalyst to provide a high molecular weight polymer;
Kochhar et al., U.S. Pat. No. 4,021,599; Beach et al., U.S. Pat. No. 4,329,255; UK Pat. No. 834,217; Calvert et al., U.S. Pat. No. 3,876,602; Fulks et al., U.S. Pat. Nos. 4,532,311 and 4,792,592; and Goode et al., U.S. Pat. No. 4,803,251. None of these patents or publications disclose the catalyst and methods of the invention. Although these later investigations extended the original work of Ziegler to produce several improved catalysts, no catalyst has exhibited the improved properties demonstrated by a catalyst of the invention. 5
In general, some of the above-identified patents and publications disclose a traditional Ziegler catalyst made from two components. These original Ziegler catalysts were characterized by a low reactivity compared to later Ziegler-type catalysts. The improved Ziegler-type 10 catalysts were higher activity catalysts formed on the surface of a solid inorganic support from an organometallic compound and a transition metal compound. The resulting Ziegler-type catalyst then was used in a polymerization reaction with a cocatalyst, like an alkyl- 15 aluminum compound. Isotacticity promoters and reactivity promoters also can be included in the polymerization reaction.
Ziegler catalysts that utilized a solid organic support, such as cellulose, were traditional Ziegler catalysts that 20 merely provided a sufficient amount of polymer to coat or encapsulate the organic support. In contrast to merely encapsulating the organic support, a catalyst of the present invention is an improved Ziegler-type catalyst and provides extensive polymerization at the internal and external surfaces of the organic support. The polymerization is sufficiently extensive that the organic support particles are fragmented by the growing polymer. This particle fragmentation provides an intimate 3Q molecular level blending of the organic support material with the polyolefin.
The prior art has addressed some of the features demonstrated by a catalyst of the invention. However, the prior art catalysts for polymerizing 1-olefins still pos- 3J sessed disadvantages. For example, in the polymerization of 1-olefins, the presence of residual catalyst in the polymer product can cause corrosion in molding machines and can introduce esthetic flaws into the molded polymer product. Accordingly, the catalyst residue was 40 stripped from the polymer product before molding. Therefore, it would be advantageous to provide a catalyst for polymerizing 1-olefins that can remain in the polymer product and not adversely affect the molding apparatus or the esthetic properties of the molded prod- 45 uct. Such a catalyst would eliminate a costly and timeconsuming step in the processing of polymerized 1-olefins.
Furthermore, researchers have attempted to discover a polymer that possesses the desirable physical and so chemical properties of a polymerized 1-olefin, and that also is biodegradable. Attempts at incorporating the feature of biodegradability into a poly-1-olefin either have failed or have adversely affected the physical properties of the polymer. Therefore, it also would be 55 advantageous to utilize a polymerization catalyst that incorporates a degree of biodegradability into a poly-1olefin. It would be especially advantageous if the catalyst could impart the feature of biodegradability, or pseudobiodegradability, into the poly-1-olefin product 60 because the need for biodegradable additives, or for comonomers, to promote biodegradability of the polymer would be eliminated. Consequently, the full benefits of the desirable physical and chemical properties of a poly-1-olefin could be realized. No known catalyst 65 useful for homopolymerizing or copolymerizing 1-olefins meets this need for imparting biodegradability into the polymer.
For example, physically blending starch and polyethylene provides a mixture exhibiting a degree of biodegradability. However, in accordance with the invention, the biodegradable component is included in the catalyst, and in accordance with another important feature of the invention, the biodegradable component is more uniformly and intimately dispersed throughout the poly-1-olefin, and the amount of the biodegradable component included in the poly-1-olefin is reduced while maintaining the same degree of biodegradability.
SUMMARY OF THE INVENTION
The invention is directed to a supported catalyst, a method of preparing the catalyst, and a method of using the catalyst, in conjunction with an organoaluminum cocatalyst, in the homopolymerization or copolymerization of 1-olefms. More particularly, the invention is directed to an improved Ziegler-type catalyst. The improved catalyst is a supported catalyst produced by: a) contacting an organometallic compound selected from the group consisting of a Group HA organometallic compound, a Group III organometallic compound, a Group IIA-Group III organometallic complex and combinations thereof with a biodegradable substrate having surface hydroxyl groups to provide a modified biodegradable substrate, then b) contacting the modified biodegradable substrate with a hydrocarbon solution of a transition metal compound, like a transition metal halide or a transition metal alkoxide, to form an inventive catalyst. The improved catalysts are stable particulate solids. The catalysts also are highly active, and can be used in particle form and in gas phase polymerization processes. Polymers synthesized using the improved catalysts demonstrate a high melt index and a narrow molecular weight distribution, thereby making the polymers well-suited for injection molding and rotational molding manufacturing applications.
The solid support material of the present catalyst is a biodegradable substrate having surface hydroxyl groups, such as a carbohydrate (e.g., cellulose or starch). Optionally, a portion of the surface hydroxyl groups of the biodegradable substrate can be modified by silylation or fluoridation prior to the modification of the remaining hydroxyl groups of the biodegradable substrate with the Group HA or Group III organometallic compound. A polymer synthesized in the presence of a present catalyst does not require a post-polymerization process step to remove catalyst residues from the polymer because the catalyst residues do not adversely affect the physical or chemical properties of the polymer or articles made therefrom. Furthermore, the polymer, or articles made therefrom, demonstrate biodegradable, or pseudobiodegradable, properties because the catalyst residues present in the polymer include the biodegradable substrate that facilitates environmental degradation of the polymer product. Present-day Ziegler-type supported catalysts utilize inorganic nonbiodegradable supports, such as silica or alumina, and do not demonstrate enhanced polymer product degradation.
Previously-used Ziegler and Ziegler-type catalysts supported on organic substrates such as cellulose did not provide a high yield of polymer relative to the substrate. The previous cellulose-supported catalysts were two component Ziegler-type catalysts that only promoted sufficient polymerization to coat or encapsulate the cellulose support. The coated cellulose support demonstrated enhanced water resistance and strength