| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | October 16, 2001 |
| PATENT TITLE |
Method for polymerization and copolymerization of alpha-olefin |
| PATENT ABSTRACT |
The present invention relates to a method of polymerization or co-polymerization of olefin under the catalyst system which comprises (a) a solid complex titanium catalyst comprising of a magnesium compound, a titanium compound, and an internal electron donor; (b) an organometallic compound of metal of Group I or Group III on the Periodic Table; and (c) two of external electron donors comprising an external electron donor (1) and an external electron donor (2), wherein the ratio of the MFR (1) to the MFR (2) is 2.about.10, the MFR (1) being that of the homopolymer (1) obtained by using said external electron donor (1) with said solid complex titanium catalyst (a) and the organometallic compound (b), and the MFR (2) being that of the homopolymer (2) obtained by using said external electron donor (2) under the identical polymerization reaction conditions of said external electron donor (1), and wherein the NMR pentads of the homopolymer (1) and the homopolymer (2), respectively, are 95.5% or more. |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | December 6, 1999 |
| PATENT FOREIGN APPLICATION PRIORITY DATA | This data is not available for free |
| PATENT CLAIMS |
What is claimed is: 1. A method for polymerization or copolymerization of .alpha.-olefin, using a catalytic system comprising: (a) a solid complex titanium catalyst comprising magnesium, a halogen-containing titanium compound, and at least one internal electron donor; (b) an organometallic compound of metal belonging to the group consisting of Groups I and III on the periodic table of elements; and (c) dicyclopentyldimethoxysilane and diisopropyldimethoxysilane as external electron donors. 2. The method for polymerization or copolymerization of .alpha.-olefin according to claim 1, in which said internal electron donor is chosen from the group of esters of monoethyleneglycol, diethyleneglycol, triethylenglycol, polyethyleneglycol, monopropyleneglycol and dipropyleneglycol. 3. The method for polymerization or copolymerization of .alpha.-olefin according to claim 1, in which the organometallic compound is trialkylaluminum. |
| PATENT DESCRIPTION |
BACKGROUND OF INVENTION The present invention relates to a method of producing olefin polymers or copolymers of high stereospecificity at a high rate of yields with a broad molecular weight distribution. In general, polypropylene has characteristics of enhanced strength and heat-resistance at a broader molecular weight distribution and higher stereospecificity. As such, many attempts were made to broaden the molecular weight distribution and improve stereospecificity. Recently, Mitsui Petrochemical Industries, Ltd. and other well-known European companies have developed a polymerization method, by means of using specific silicon compounds, for polymers of high yields and stereospecificity (e.g., Korean Pat. Pub. No. 92-2488, U.S. Pat. No. 4,990,479, EP Laid-Open No. 350,170A, Chinese Pat. No. 1,040,379), as compared to those of the conventional methods. However, it was very difficult to produce polymers of the broad molecular weight and high MFR (Melt Flow Rate) due to the low hydrogen response. Further, in order to broaden the molecular weight distribution of the polymers, it was common to use a method of producing and then mixing olefin polymers of different molecular weight distributions from one another in a number of polymerization reactors. Yet, this method takes too much time and has disadvantages in that the products thereof are non-homogeneous. In a recent report, from Mitsui Petrochemical of Japan(publication No. 93-665, of Korea Patent), a method has been proposed in which an olefin polymer with a wider distribution of molecular weights is produced by the use of two particular electron donors, from which homopolyolefins having the ratio of the melt flow rate (MFR) if greater than 31.6 are respectively polymerized in the same polymerization conditions. In this case, however, the catalyst's activity is reduced too low and the stereospecificity of polymer is too low for it to be commercially useful. Meanwhile, many other techniques are known to produce polymers or copolymers of high stereospecificity by the use of solid complex titanium catalysts containing magnesium with electron donors, and also titanium and a halogen, as catalyst for polymerization or copolymerization of .alpha.-olefin which contains more than three atoms of carbon (e.g. Japanese, Pts. Laid-Open Nos. S48-16986 and S48-16987, Ger. Pts. Laid-Open Nos. 2,153,520; 2,230,672; 2,230,728; 2,230,752; and 2,553,104) These references reveal the use of mixture components of particular catalysts and the process for forming these catalysts. As is well known, the characteristics of these catalysts, containing solid complex titanium, vary from catalyst to catalyst, in accordance with the different mixtures of components, different combinations of processes for formation, and the different combinations of these conditions. Therefore, it is very difficult to predict what effects can be obtained from a catalyst produced under a given set of conditions. Often, a catalyst having undesirable effect is produced. It is also often true that such characteristics as the activity of the catalyst or the stereospecificity of the polymer do not turn out to be adequate even if the catalyst is made under proper conditions, if proper external electron donors are not used. The solid complex titanium catalyst containing magnesium, titanium, and halogen is no exception. In polymerizing or copolymerizing .alpha.-olefin containing more than three atoms of carbon, in the presence of hydrogen and with the use of a catalyst composed of titanium and an organometallic compound of metals belonging to Groups I through IV on the periodic table of elements, if a co-catalyst composed of titanium trichloride obtained by reducing titanium tetrachloride using metallic aluminum, hydrogen, or an organic aluminum compound is used, along with such electron donors as are known to restrain the formation of amorphous copolymer, the effects vary depending upon the electron donors used. The cause is accepted to be that the electron donors are not mere inert additives, rather, they combine with the magnesium and titanium compounds electronically and sterically, thereby fundamentally altering the structure of the solid complex catalyst. SUMMARY OF INVENTION In an embodiment, a method of producing olefin polymers and co-polymers of broad molecular weight distribution, to the extent of a high MFR, while maintaining high stereospecificity and activity of a catalyst is described. In another embodiment, the present invention provides a method for producing a polypropylene and propylene copolymer adequate for use in production of film easily capable of being heat-sealed, transparent, and anti-blocking property, also adequate for impact resistance, fluidity and low temperature heat-sealable is described. DETAILED DESCRIPTION OF INVENTION The present invention provides a method for polymerizing or copolymerizing an .alpha.-olefin using the catalyst system comprising: (a) a solid complex titanium catalyst containing magnesium, a halogen-containing titanium compound, and, as internal electron donor, an ester polycarboxylate; (b) an organometallic compound of a metal of Group I and III on the periodic table of elements; (c) two of external electron donors comprising an external electron donor (1) and an external electron donor (2), wherein the ratio of the MFR (1) to the MFR (2) is 2.about.10, the MFR (1) being that of the homopolymer (1) obtained by using said external electron donor (1) with said solid complex titanium catalyst (a) and the organometallic compound (b), and the MFR (2) being that of the homopolymer (2) obtained by using said external electron donor (2) under the identical polymerization reaction conditions of said external electron donor (1), and wherein the NMR pentads of the homopolymer (1) and the homopolymer (2), respectively, are 95.5% or more. The solid complex titanium catalyst (a) used for polymerization or copolymerization of an .alpha.-olefin includes magnesium, a halogen-containing titanium compound, and, as internal electron donor, ester polycarboxylate. The solid complex titanium catalyst used in the present invention has an excellent level of catalytic activity, compared with existing titanium catalysts, and is capable of creating a polymer having a broad molecular weight distribution and a high stereospecificity. It has a halogen/titanium molar ratio more than about 4; it is also a solid complex with practically no titanium compound separating out when washed in hexane at room temperature. The chemical construction of this solid complex is not known but it is presumed that the atoms of magnesium, as well as those of titanium, are firmly linked by halogen. In an embodiment of the solid complex titanium used in the present invention, the halogen/titanium molar ratio is more than about 5, preferably more than about 8; a magnesium/titanium molar ratio over about 3, further preferably from about 5 to about 50, the electron donor/titanium molar ratio about 0.2 to about 6, preferably about 0.4 to about 3, even more preferably about 0.8 to about 2. The specific surface area is more than 10 m.sup.2 /g, preferably more than about 50 m.sup.2 /g, more preferably more than about 100 m.sup.2 /g. The X-ray spectrum of the solid complex titanium catalyst preferably shows either amorphous characteristics in disregard of the starting magnesium, or characteristics more amorphous than ordinary magnesium dihalide on the market. The solid complex titanium catalyst may be produced by many methods. As the most widely practiced method, contacting a non-reductive magnesium compound with a titanium compound which contains halogen(s), and treating the product thereof, if necessary, with an electron donor, and these methods can all be used in the present invention also. Some of these methods are revealed in Ger. Pts. Laid-Open Nos. 2,230,672; 2,504,036; 2,553,104; and 2,605,922; and Japanese Pat. Laid-Open Nos. S51-28189; S51-136625; and 52-87486. The conventional method for producing the solid complex titanium compound, beginning from a liquid magnesium solution and containing an electron donor in the form of a liquid titanium compound, is described in Japanese pat. Laid-Open No. S54-40293. The non-reductive magnesium compounds may include such magnesium halides as magnesium chloride, magnesium bromide, magnesium iodide, and magnesium fluoride; such alkoxymagnesium halides as methoxy magnesium chloride, ethoxymagnesium chloride, isopropoxymagnesium chloride, butoxymagnesium chloride, octoxymagnesium chloride; such aryloxymagnesium halides as phenoxymagnesium chloride, and methylphenoxymagnesium chloride; such alkoxymagnesiums as ethoxymagnesium, isopropoxymagnesium, butoxymagnesium and octoxymagnesium; such aryloxymagnesium as phenoxymagnesium and dimethylpenoxymagnesium; and such magnesium salts of acid as laurylmagnesium and magnesium stearate. Magnesium compounds may be used in complex compounds whit other metals or with mixtures of other metals. A mixture of two or more magnesium compounds may also be used. Preferable magnesium compounds are halogen-containing magnesium compounds, and more preferable are magnesium chloride, alkoxymagnesium chloride, most preferably alkoxymagnesium chloride and aryloxymagnesium chloride which have C1 to C14 alkoxy group, yet preferably aryloxymagnesium chloride which has C6 to C20 aryloxy group. The magnesium compounds listed above can be generally represented by brief general expressions, but there arise occasions at times where other closely related magnesium compounds cannot be, because of different production methods. In such case, they are generally believed to be mixtures of these compounds. For instance, those compounds obtained by reacting magnesium metals with alcohol or phenol in the presence of halosilane, phosphorus pentachloride, or thionyl chloride, or by heat-dissolution of Grignard reagent, or by dissolving Grignard reagent using hydroxyl groups, carbonyl ester groups, ether groups or others are all considered mixtures of a variety of compounds accordant with the different reagents or the different degrees of reaction; such compounds are also usable in the present invention. In an embodiment, non-reductive liquid magnesium compounds or solutions of magnesium compounds in hydrocarbon solvents are mainly used. Such compounds in the liquid state can be produced by reacting the non-reductive magnesium compounds listed above with at lest one or more electron donors chosen from a group that includes alcohol, organic carboxylic acid, aldehyde, amines, and their mixtures in the presence or absence of a hydrocarbon solvent which can dissolve those magnesium compounds given above. The hydrocarbon solvents used for the purpose include, for example, aliphatic hydrocarbons such as pentane, hexane, heptane, octane, decane, dodecane, and kerosene; alicyclic hydrocarbons such as cyclopentane, methylcyclopentane, cyclohexane, and methylcyclohexane; such aromatic hydrocarbons as benzene, toluene, xylene, ethylbenzene, cumen, and cymen; and halogenated hydrocarbons such as dichloroethane, dichloropropane, dichloroethylene, trichloroethylene, carbon tetrachloride, and chlorobenzene. The magnesium compound solution of hydrocarbon solvents, can be produced by simple mixture, or by heating during mixing, or by mixing in the presence of an electron donor selected from the group that includes alcohol, aldehyde, amine, carboxylic acid, or their mixtures, or even by mixing these mixtures with other electron donors and heating them. However, this production method can be altered depending upon the type of magnesium and the solutions. When dissolving hydrogen-containing magnesium compound in a hydrocarbon solution, using alcohol as the electron donor, the quantities and proportions of the alcohol may differ depending upon the quantity and kinds of magnesium compounds and the hydrocarbon solvent, but it is desirable to use at least 0.5 mol of an alcohol per 1 mol of the magnesium compound, preferably 1.0 to 20 mols, more preferably about 2.0 mols to about 10 mols. In the case where alcohol having at least 6 atoms of carbon is used, if at least 0.5 mol, or preferably at least 1.0 mol of alcohol, per 1 mol of the halogen-containing magnesium compound, the halogen-containing compound can be dissolved and a catalyst component with high activity can be obtained with the use of only a small quantity of alcohol. If alcohol with 5 or fewer carbon atoms is used, the total quantity of the alcohol should be at least about 15 mols to 1 mol of the magnesium compound, and the catalyst component thus produced will have lower activity than when alcohol is used in the way stated above. Meanwhile, if aromatic hydrocarbon is used as the hydrocarbon solvent, the hydrogen-containing magnesium compound can be dissolved, regardless of the type of alcohol, by about 20 mols, preferably about 1.5 mols to 12 mols of alcohol, per 1 mol of the magnesium compound. The reaction of halogen-containing magnesium and alcohol is performed preferably in a hydrocarbon solvent. This reaction is performed, dependent upon the kinds of the magnesium compound and alcohol, at room temperature or higher, e.g. in the range from about 30 degrees C. to 200 degrees C., or more preferably about 60 degrees C. to 150 degrees C., for a time in the range from about 15 minutes to about 5 hours, more preferably about 30 minutes to about 3 hours. The alcohols used as electron donors in formation of a liquid magnesium compound include such aliphatic alcohols as 2-methylpentanol, 2-ethylpentanol, 2-ethylbutanol, n-heptanol, n-octanol, 2-thylhexanol, decanol, dodecanol, tetradecyl alcohol, undecanol, oleyl alcohol, and stearyl alcohol; such alicyclic alcohols as cyclohexanol and methylcyclohexanol; and such aromatic alcohols as benzyl alcohol, methylbenzyl alcohol, isopropylenebenzylalcohol, a-methylbenzyl alcohol, and a,a-dimethylbenzyl alcohol, which all have at least 6 or, preferably 6 to 20 carbon atoms. For alcohols with 5 or fewer carbon atoms, methanol, ethanol, propanol, butanol, ethyleneglycol and methylcarbitol and the like can be used. The magnesium compounds in liquid form, produced as above, are crystallized into globular solids once again with the use of silicon tetrahalide, silicon alkylhalide, tin tetrahalide, tin alkylhalide, tin hydrohalide, titanium tetrahalide, and the like. The quantity of silicon compounds, tin compounds, or titanium compounds for use in the recrystallizing of liquid magnesium compounds into globular solids may be varied form case to case. It can be 0.1 mol to 20 mols per 1 mol of the magnesium compound. Preferably, it is 0.1 mol to 10 mols, more preferably 0.2 mol to 2 mols. The shapes and magnitudes of the magnesium carriers will also vary accordant with the conditions of the reaction. At the time of mixing the two compounds they must be maintained at a properly low temperature in order for them not to solidify during the reaction, with the product then being slowly heated to yield a solid. The temperature for recrystallizing of a liquid magnesium compound ranges from about -70 degrees C. to about 200 degrees C. In general, to obtain granular or globular forms high temperature is, preferably, avoided during the process of mixing. However, if the temperature of reaction is too low, precipitation of solid products will not take place, and, therefore, this reaction should be performed, preferably, at about 20 degrees C. to 150 degrees C. The magnesium compound thus obtained may be reacted with a liquid titanium compound, in the presence of an internal electron donor, whereby a solid complex titanium catalyst is obtained. The titanium compound in liquid form to be reacted with a magnesium compound is preferably the tetravalence titanium compound in the general expression: Ti(OR).sub.m X.sub.4-m (wherein R is a hydrocarbon group, X halogen atoms, m is a number from 0 to 4). The R represents an alkyl group with from 1 through 10 carbon atoms. Various titanium compounds can be used, titanium tetrahalides such as TiCl.sub.4, TiBr.sub.4, and Til.sub.4, alkoxytitanium trihalides such as Ti(OCH.sub.3)Cl.sub.3, Ti(OC.sub.2 H.sub.5)Cl.sub.3, Ti(OC.sub.4 H.sub.9)Cl.sub.3, Ti(OC.sub.2 H.sub.5)Br.sub.3, and Ti(O(i-C.sub.2 H.sub.5))Br.sub.3 ; alkoxytitanium dihalides such as Ti(OCH.sub.3).sub.2 Cl.sub.2, Ti(OC.sub.2 H.sub.5).sub.2 Cl.sub.2, Ti(OC.sub.4 H.sub.9).sub.2 Cl.sub.2, and Ti(OC.sub.2 H.sub.5).sub.2 Br.sub.2 ; alkoxytitanium halides such as Ti(OCH.sub.3).sub.3 Cl, Ti(OC.sub.2 H.sub.5).sub.3 Cl, Ti(OC.sub.4 H.sub.9).sub.3 Cl, and Ti(OC.sub.2 H.sub.5).sub.3 Br; and tetraalkoxytitanium mixtures such as Ti(OCH.sub.3).sub.4, Ti(OC.sub.2 H.sub.5).sub.4, and Ti(OC.sub.4 H.sub.9).sub.4. The titanium compound is used in a proportion of at least 1 mol, preferably 3mols to about 200 mols, or, more preferably, approximately 5 mols to 100 mols, per 1 mol of the non-reductive magnesium compound. It is preferable to mix the magnesium compound with the liquid titanium compound at a low temperature, slowly raising it. For instance, the two compounds are brought into contact at -70 degrees C. to about 50 degrees C. at first to avoid a quick reaction, and the temperature is slowly raised to a temperature in the range from about 50 degrees C. to 150 degrees C. for the reaction to take effect for sufficient time, after which the product is washed in the hydrocarbon used for the polymerization reaction until no isolated titanium is detected. By this method an excellent solid complex titanium catalyst can be produced. The internal electron donors used in production of the solid complex titanium catalyst can be generally, oxygen-containing electron donors such as water, alcohols, phenols, aldehydes, carboxylic acids, esters, ethers, and acid amides; along with nitrogen-containing electron donors such as ammonia, amines, nitrites, and isocyanate; and particularly alcohols having from 1 to 18 carbon atoms such as methanol, ethanol, propanol, pentanol, hexanol, octanol, dodecanol, octadecylalcohol, benzylalcohol, phenylethylalcohol, cumylalcohol, and isopropylbenzylalcohol; ketones which have from 6 to 15 carbon atoms and which can contain lower alkyl groups such as phenol, cresol, xylene, ethylphenol, propylphenol, cumylphenol, and naphthol; aldehydes which have from 2 to 15 carbon atoms such as acetaldehyde, propionaldehyde, octylaldehyde, benzaldehyde, tolualdehyde, and naphthalaldehyde; organic acid esters having from 2 to 18 carbon atoms such as methyl formate, methyl acetate, ethyl acetate, vinyl acetate, propyl acetate, octyl acetate, cyclohexyl acetate, ethyl propionate, methyl butyrate, ethyl valerate, chloromethyl acetate, dichloroethyl acetate, methyl methacrylate, ethyl crotonate, ethyl cyclohexyl carboxylate, phenyl benzoate, benzyl benzoate, methyl toluate, ethyl toluate, amyl toluate, ethyl ethyl benzoate, methyl anisate, ethyl anisate, ethyl ethoxybenzoate, g-butyrolactone, s-valerolactone, cumalin, phthalide, cyclohexyl acetate, ethyl propionate, methyl butyrate, methyl valerate, methyl chloroacetate, ethyl dichloroacetate, methyl methacrylate, ethyl cycloate, phenyl benzoate, ethyl toluate, ethyl toluate, propyl benzoate, butyl benzoate, cyclohexyl benzoate, amyl toluate, methylene carbonate, and ethylene carbonate; halogen compounds having from 2 to 15 carbon atoms such as acetyl chloride, benzyl chloride, chlorotoluate, and chloroanisate; ethers such as methyl ether, ethyl ether, ispropyl ether, butyl ether, amyl ether, tetrahydrofuran, anisole and diphenyl ether; amines such as methyl amine, ethyl amine, diethyl amine, tributyl amine, piperidine, tribenzyl amine, aniline, pyridine, pyroline, and tetramethylene diamine; nitriles such as acetonitrile, benzonitrile, and tolunitrile; and compounds of aluminum, silicon, tin, and the like which have the above-said functional groups in their molecules; in addition to these, catalysts reacted with certain electron donors are used in the present invention to produce an .alpha.-olefin polymer with improved stereospecificity and greater yield than otherwise. The preferable internal electron donors used in the present invention to produce a solid complex titanium catalyst are, in particular, ester derivatives of monoethylene glycol(MEG), diethylene glycol(DEG), triethylene glycol(TEG), polyethylene glycol(PEG), monopropylene glycol(MPG), and dipropylene glycol(DPG) such as, acetate, propionate, n- and iso-butyrate, benzoate, toluate, etc., the benzoates are monoethylene glycol monobenzoate, monoethylene glycol dibenzoate, diethylene glycol monobenzoate, diethylene glycol dibenzoate, diethylene glycol monobenzoate, triethylene glycol dibenzoate, monopropyl glycol monobenzoate, dipropylene glycol monobenzoate, tripropylene glycol monobenzoate, and others. These electron donors can be used in a mixture of two or more kinds, and particularly, esters of the aromatic group are preferable. These electron donors are not always needed at the start, they may also be introduced during the production of the solid complex titanium catalyst, and they may also be used as additives to other compounds or in the form of a complex. The quantity of the internal electron donor can be changed as required. It may be about 0.01 mol to about 10 mols, preferably about 0.01 mol to 5 mols, or further preferably 0.05 mol to about 1 mol, per 1 mol of the magnesium compound. The polymers obtained through a slurry polymerization by using the resultant solid catalyst are granular or globular with excellent stereospecificity, a high bulk density, and good fluidity. The aforesaid solid complex titanium catalyst can be profitably used in polymerization of such olefins as ethylene, propylene, and 1-butene or 4-methyl-1-pentene. This catalyst can be especially profitably used in the polymerization of .alpha.-olefin which has three or more carbon atoms, copolymerization of these, copolymerization of .alpha.-olefins which have ethylene by less than 10 mols, and in copolymerization of .alpha.-olefins which have both conjugated and nonconjugated dienes. The organometallic compounds (b) used in the method of the present invention include, in particular, trialkyl aluminums such as triethyl aluminum and tributyl aluminum; alkenyl aluminum such as triisoprenyl aluminum; partly alkoxyfied alkyl aluminums, for example, dialkylaluminum alkoxides such as diethylaluminum ethoxide and dibutylaluminum butoxide; alkylaluminum sesquibalides and ethylaluminum dichlorides such as ethylaluminum sesquiethoxide and butylaluminum sesquiethoxide; alkylaluminum dihalide such as propylaluminum dichloride and butylaluminum dibromide; partly halogenized aluminum, for example, dialkylaluminum hydrides and ethylaluminum ethoxychlorides such as diethylaluminum hydrides and dibutylaluminum hydride; and partly alkoxyfied and halogenized alkyl aluminums such as butylaluminum butoxychloride and ethylaluminum ethoxybromide. In addition to said solid complex titanium catalyst (a) and the organometallic compound (b), the present invention uses, as an external electron donor component (c), under the equivalent reaction conditions of polymerization, a mixture of an external electron donor (1) which polymerizes to high stereospecificity the polymers of relatively high molecular weight, and an external electron donor (2) which polymerizes to high stereospecificity the polymers of relatively low molecular weight. Consequently, the present invention can produce polymers of high stereospecificity with a broad molecular weight distribution. The mix ratio of the external electron donor (1) to the external electron donor (2), constituting the external electron donor component (c), is 0.05:0.95 to 0.95:0.05 in terms of molar ratio, preferably 0.1:0.9 to 0.9:0.1, or more preferably 0.3:0.7 to 0.7:0.3. As for the external electron donor (1) used in the present invention, it is per 1 mol of the titanium atoms in the solid complex titanium catalyst (a) is from about 1 mol to 2,000 mols, preferably about 5 mols to about 500 mols. The ratio of component (c) of external electron donors being from about 0.001 mol to 10 mols, or preferably about 0.01 mol to about 2 mol, more preferably about 0.05 mol to about 1 mol per 1 mol of the aluminum atoms of the components (b), as measured in terms of the silicon atoms. The polymerization reaction using the catalyst of the invention is performed in the same way as in the ordinary method where a Ziegler-type catalyst is used. Note that this reaction is performed in the absence of oxygen and water. The olefin polymerization reaction is performed, preferably, at a temperature in the range from about 20 degrees C. to 200 degrees C., more preferably at about 50 degrees C. to 180 degrees C., and under a pressure ranging from about normal atmospheric pressure to 100 atmospheres, preferably from about 2 atmospheres to 50 atmospheres. The reaction can be performed either by batches, or semi-batch, or continuously, and can also be performed in two or more steps with different reaction conditions. |
| PATENT EXAMPLES | available on request |
| PATENT PHOTOCOPY | available on request |
|
Want more information ? Interested in the hidden information ? Click here and do your request. |