A composition comprising a hydrocarbon polymer having {overscore (M)}n ranging from 20,000 to about 500,000, when the polymer is not a star polymer, and up to about GPC peak molecular weight of 4,000,000 when the polymer is a star polymer having attached thereto pendant groups Aa and Bb wherein each A is independently a member of the group of formula xe2x80x94Qxe2x80x94Kk wherein each Q is independently an aliphatic or aromatic hydrocarbon group, each K is independently a member selected from the group consisting of amide groups, nitrile groups, ester groups and carboxylic acid groups, and each k is independently a number ranging from 1 to about 3, and when kxe2x89xa72, groups xe2x80x94K on adjacent carbon atoms, taken together, may constitute a succinimide group, and a is 0 or a number ranging from 1 to about 50; and each B is independently a member of the group of formula:

This invention relates to dispersant-viscosity improvers for lubricating oils and fuels, processes for preparing them, additive concentrates, and lubricating oil and fuel compositions.
The viscosity of hydrocarbonaceous liquids, for example fuels and lubricating oils, particularly the viscosity of mineral oil based lubricating oils, is generally dependent upon temperature. As the temperature of the oil is increased, the viscosity usually decreases.
The function of a viscosity improver is to reduce the extent of the decrease in viscosity as the temperature is raised or to reduce the extent of the increase in viscosity as the temperature is lowered, or both. Thus, a viscosity improver ameliorates the change of viscosity of an oil containing it with changes in temperature. The fluidity characteristics of the oil are improved.
Viscosity improvers are usually polymeric materials and are often referred to as viscosity index improvers.
Dispersants are also well-known in the art. Dispersants are employed in lubricants to keep impurities, particularly those formed during operation of mechanical devices such as internal combustion engines, automatic transmissions, etc. in suspension rather than allowing them to deposit as sludge or other deposits on the surfaces of lubricated parts.
Multifunctional additives that provide both viscosity improving properties and dispersant properties are likewise known in the art. Such products are described in numerous publications including Dieter Klamann, xe2x80x9cLubricants and Related Productsxe2x80x9d, Verlag Chemie Gmbh (1984), pp. 185-193; C. V. Smalheer and R. K. Smith, xe2x80x9cLubricant Additivesxe2x80x9d, Lezius-Hiles Co. (1967); M. W. Ranney, xe2x80x9cLubricant Additivesxe2x80x9d, Noyes Data Corp. (1973), pp. 92-145, M. W. Ranney, xe2x80x9cLubricant Additives, Recent Developmentsxe2x80x9d, Noyes Data Corp. (1978), pp. 139-164; and M. W. Ranney, xe2x80x9cSynthetic Oils and Additives for Lubricantsxe2x80x9d, Noyes Data Corp. (1980), pp. 96-166. Each of these publications is hereby expressly incorporated herein by reference.
Dispersant-viscosity improvers are generally prepared by functionalizing, i.e., adding polar groups, to a hydrocarbon polymer.
Hayashi et al, U.S. Pat. No. 4,670,173 relates to compositions suitable for use as dispersant-viscosity improvers made by reacting an acylating reaction product which is formed by reacting a hydrogenated block copolymer and an alpha,beta olefinically unsaturated reagent in the presence of free-radical initiators, then reacting the acylating product with a primary amine and optionally with a polyamine and a mono-functional acid.
Chung et al, U.S. Pat. No. 5,035,821 relates to viscosity index improver-dispersants comprised of the reaction products of an ethylene copolymer grafted with ethylenically unsaturated carboxylic acid moieties, a polyamine having two or more primary amino groups or polyol and a high functionality long chain hydrocarbyl substituted dicarboxylic acid or anhydride.
Van Zon et al, U.S. Pat. No. 5,049,294, relates to dispersant/VI improvers produced by reacting an alpha,beta-unsaturated carboxylic acid with a selectively hydrogenated star-shaped polymer then reacting the product so formed with a long chain alkane-substituted carboxylic acid and with a C1 to C18 amine containing 1 to 8 nitrogen atoms and/or with an alkane polyol having at least two hydroxy groups or with the preformed product thereof.
Bloch et al, U.S. Pat. No. 4,517,104, relates to oil soluble viscosity improving ethylene copolymers reacted or grafted with ethylenically unsaturated carboxylic acid moieties then with polyamines having two or more primary amine groups and a carboxylic acid component or the preformed reaction product thereof.
Gutierrez et al, U.S. Pat. No. 4,632,769, describes oil-soluble viscosity improving ethylene copolymers reacted or grafted with ethylenically unsaturated carboxylic acid moieties and reacted with polyamines having two or more primary amine groups and a C22 to C28 olefin carboxylic acid component.
Lange, et al, U.S. Pat. No. 4,491,527 relates to ester-heterocycle compositions useful as xe2x80x9clead paintxe2x80x9d inhibitors in lubricants. The compositions comprise derivatives of substituted carboxylic acids in which the substituent is a substantially aliphatic, substantially saturated hydrocarbon based radical containing at least about 30 aliphatic carbon atoms; said derivatives being the combination of: (A) at least one ester of said carboxylic acids in which all the alcohol moieties are derived from at least on mono- or polyhydroxyalkane; and (B) at least one heterocyclic condensation product of said substituted carboxylic acids containing at least one heterocyclic moiety which includes a 5- or 6-membered ring which contains at least two ring hetero atoms selected from the group consisting of oxygen, sulfur and nitrogen separated by a single carbon atom, at least one of said hetero atoms being nitrogen, and at least one carboxylic moiety; the carboxylic and heterocyclic moieties either being linked through an ester or amide linkage or being the same moiety in which said single carbon atom separating two ring hetero atoms corresponds to a carbonyl carbon atom of the substituted carboxylic acid.
Lange, et al, U.S. Pat. No. 5,512,192 teach dispersant viscosity improvers for lubricating oil compositions comprising a vinyl substituted aromatic-aliphatic conjugated diene block copolymer grafted with an ethylenically unsaturated carboxylic acid reacted with at least one polyester containing at least one condensable hydroxy group and at least one polyamine having at least one condensable primary or secondary amino group, and optionally, at least one hydrocarbyl substituted carboxylic acid or anhydride.
Lange, U.S. Pat. No. 5,540,851 describes dispersant viscosity improvers for lubricating oil compositions which are the reaction product of (a) an oil soluble ethylene-alpha olefin copolymer wherein the alpha olefin is selected from the group consisting of C3-28 alpha olefins, said polymer having a number average molecular weight ranging from about 30,000 to about 300,000 grafted with an ethylenically unsaturated carboxylic acid or functional derivative thereof, with at least one polyester containing at least one condensable hydroxyl group, and at least one polyamine having at least one condensable primary or secondary amino group, and optionally at least one hydrocarbyl substituted carboxylic acid or anhydride.
Each of these patents is hereby expressly incorporated herein by reference.
For additional disclosures concerning multi-purpose additives and particularly viscosity improvers and dispersants, the disclosures of the following United States patents are incorporated herein by reference:
Many such additives are frequently derived from carboxylic reactants, for example, acids, esters, anhydrides, lactones, and others. Specific examples of commonly used carboxylic compounds used as intermediates for preparing lubricating oil additives include alkyl- and alkenyl substituted succinic acids and anhydrides, polyolefin substituted carboxylic acids, aromatic acids, such as salicylic acids, and others. Illustrative carboxylic compounds are described in Meinhardt, et al, U.S. Pat. No. 4,234,435; Norman et al, U.S. Pat. No. 3,172,892; LeSuer et al, U.S. Pat. No. 3,454,607, and Rense, U.S. Pat. No. 3,215,707.
All of the foregoing patents and publications and all of those mentioned hereinafter are hereby incorporated herein by reference.
Many carboxylic intermediates used in the preparation of lubricating oil additives contain chlorine. While the amount of chlorine present is often only a very small amount of the total weight of the intermediate, the chlorine frequently is carried over into the carboxylic derivative which is desired as an additive. For a variety of reasons, including environmental reasons, the industry has been making efforts to reduce or to eliminate chlorine from compositions designed for use as lubricant or fuel additives.
Accordingly, it is desirable to provide low chlorine or chlorine free derivatives for use as additives in lubricants.
A further object is to provide processes for preparing such additives.
Other objects will in part be obvious in view of this disclosure and will in part appear hereinafter.
This invention relates to a composition comprising a hydrocarbon polymer having Mn ranging from 20,000 to about 500,000, when the polymer is not a star polymer, and up to about GPC peak molecular weight of 4,000,000 when the polymer is a star polymer having attached thereto pendant groups Aa and Bb wherein each A is independently a member of the group of formula xe2x80x94Qxe2x80x94Kk wherein each Q is independently an aliphatic or aromatic hydrocarbon group, each k is independently a number ranging from 1 to about 4, and each K is independently a member selected from the group consisting of amide groups, nitrile groups, carboxylic acid groups and ester groups, and, when kxe2x89xa72, groups xe2x80x94K on adjacent carbon atoms, taken together, may constitute an imide group, and a is 0 or a number ranging from 1 to about 50; and each B is independently selected from members of the group of formula:
wherein each X is independently O, S, or NRb, each Rb is independently H, NH2, hydrocarbyl, hydroxyhydrocarbyl, or aminohydrocarbyl, each s is independently 1 or 2, and each Z is independently a hydrocarbyl group, optionally substituted with one or more carboxylic acid groups or amide groups, each Ra is independently an ethylene group, a propylene group, which groups optionally have hydrocarbyl or hydroxhydrocarbyl substituents, or
wherein J is H, SH, NH2, or OH, and tautomers thereof; and b is a number ranging from 1 to about 50 with the proviso that when X is O, then b ranges from 2 to about 50.
As used herein, the terms xe2x80x9chydrocarbonxe2x80x9d, xe2x80x9chydrocarbylxe2x80x9d or xe2x80x9chydrocarbon basedxe2x80x9d mean that the group being described has predominantly hydrocarbon character within the context of this invention. These include groups that are purely hydrocarbon in nature, that is, they contain only carbon and hydrogen. They may also include groups containing substituents or atoms which do not alter the predominantly hydrocarbon character of the group. Such substituents may include halo-, alkoxy-, nitro-, etc. These groups also may contain hetero atoms. Suitable hetero atoms will be apparent to those skilled in the art and include, for example, sulfur, nitrogen and oxygen. Therefore, while remaining predominantly hydrocarbon in character within the context of this invention, these groups may contain atoms other than carbon present in a chain or ring otherwise composed of carbon atoms provided that they do not adversely affect reactivity or utility of the process or products of this invention.
In general, no more than about three non-hydrocarbon substituents or hetero atoms, and preferably no more than one, will be present for every 10 carbon atoms in the hydrocarbon or hydrocarbon based groups. Most preferably, the groups are purely hydrocarbon in nature, that is, they are essentially free of atoms other than carbon and hydrogen.
Throughout the specification and claims the expression oil soluble or dispersible is used. By oil soluble or dispersible is meant that an amount needed to provide the desired level of activity or performance can be incorporated by being dissolved, dispersed or suspended in an oil of lubricating viscosity. Usually, this means that at least about 0.001% by weight of the material can be incorporated into a lubricating oil. For a further discussion of the terms oil soluble and dispersible, particularly xe2x80x9cstably dispersiblexe2x80x9d, see U.S. Pat. No. 4,320,019 which is expressly incorporated herein by reference for relevant teachings in this regard.
The expression xe2x80x9clowerxe2x80x9d is used throughout the specification and claims. As used herein to describe various groups, the expression xe2x80x9clowerxe2x80x9d is intended, unless expressly indicated otherwise, to mean groups containing no more than 7 carbon atoms, more often, no more than 4, frequently one or two carbon atoms.
The Hydrocarbon Polymer with Groups A and B
The hydrocarbon polymer onto which are attached groups A and B is derived from (P) a hydrocarbon polymer as described in greater detail hereinafter, and optionally, mixtures of the polymer (P) and additional reactants, often olefinically unsaturated compounds, having molecular weight ranging from about 100 to less than 20,000.
When mixtures are used, they typically comprise from about 1% by weight, often from about 5%, occasionally from about 10% up to about 50% by weight, often up to about 25% by weight of olefinically unsaturated compound having molecular weight ranging from about 100 to less than 20,000.
The polymer onto which groups A and B are attached may contain up to about 5% residual olefinic unsaturation, that is, up to about 5% of the carbon to carbon bonds may be olefinically unsaturated. Preferably, no more than about 1%, even more often no more than about 0.1% of the carbon to carbon bonds are unsaturated. Most preferably the polymer with groups A and B is substantially saturated, that is, all of the carbon to carbon bonds are saturated or only a minor, insignificant number of carbon to carbon bonds are olefinically unsaturated.
The extent of olefinic unsaturation which may remain in the hydrocarbon polymer after attachment of groups A and B may be adjusted by hydrogenation of some or all of the olefinic bonds present in (P) before reaction with (M) an xcex1,xcex2-unsaturated carboxylic compound as described in greater detail hereinafter. Alternatively, the intermediate arising from reaction of (P) and (M) may be hydrogenated, if desired to reduce or eliminate remaining unsaturation.
The groups A and B attached to the hydrocarbon polymer are described in greater detail hereinbelow.
The Group A
The hydrocarbon polymer may have attached thereto one or more groups A which consist of groups of the formula
xe2x80x94Qxe2x80x94Kk
wherein each Q is independently an aliphatic or aromatic hydrocarbon group, each K is independently a member selected from the group consisting of amide groups, nitrile groups, ester groups and carboxylic acid groups, and each k is independently a number ranging from 1 to about 4, and when kxe2x89xa72, groups xe2x80x94K on adjacent carbon atoms, taken together, may constitute a succinimide group, and the subscript a is 0 or a number ranging from 1 to about 50.
The subscript a denotes the number of A groups. The subscript a is 0 or ranges from 1 to about 50. When a=0, the group A is absent. Often, a ranges from 1 to about 10. Preferably, A is a succinimide group and a ranges from 1 to about 10.
The Group B
The hydrocarbon polymer has attached thereto one or more groups B, each of which is independently selected from members of the group of formula:
wherein each X is independently O, S, or NRb, each Rb is independently H, NH2, hydrocarbyl, hydroxy-hydrocarbyl or aminohydrocarbyl, and each Z is independently a hydrocarbyl group, preferably an aliphatic group, more preferably an ethylene or propylene group, optionally substituted with one or more carboxylic acid groups or amide groups, Ra is an ethylene group, a propylene group, which groups optionally have hydrocarbyl or hydroxyhydrocarbyl substituents, or
wherein J is H, SH, NH2, or OH, and tautomers thereof; and the subscript b is a number ranging from 1 to about 30.
The compositions of this invention may be prepared by a process which comprises first grafting onto (P) the hydrocarbon polymer having {overscore (M)}n ranging from 20,000 to about 500,000, when the polymer is not a star polymer, and up to about GPC peak molecular weight of 4,000,000 when the polymer is a star polymer, from 1 to about 50 moles, per mole of polymer, of (M) at least one alpha-beta unsaturated carboxylic acid or functional derivative thereof to form a carboxylic group containing intermediate, then reacting said intermediate with (C) from about 0.5 to about 1.25 equivalents, per equivalent of carboxylic acid or functional derivative thereof, of a heterocycle precursor.
The amount of (M) reacted per mole of (P) may depend, in part, on the amount of olefinic unsaturation present in (P). For use as an intermediate for further reaction with (C) to prepare dispersant-viscosity improver additives for lubricating oils, the amount of (M) reacted with (P) often will range from about 1 to about 100 moles (M) per mole of (P) wherein one mole of (P) is defined herein as the number average molecular weight of (P). Preferably, in this embodiment from about 2, often from about 5, up to about 100 moles (M), often up to about 20, frequently up to about 10 moles (M) are utilized per mole of (P). In another embodiment, the xcex1,xcex2-unsaturated carboxylic acid is employed in amounts ranging from about 0.01% to 10%, preferably 0.1-5%, more preferably 0.2-2% by weight, based on the weight of polymer.
The step of this invention comprising reacting (P) and (M) is conducted at temperatures ranging from ambient, usually from about 60xc2x0 C., often from about 100xc2x0 C., up to about 250xc2x0 C., more often up to about 180xc2x0 C., preferably up to about 160xc2x0 C. Depending upon the nature of the polymer (P), the reaction may be conducted via the xe2x80x9cenexe2x80x9d process, via halogen, usually chlorine, assisted thermal grafting, or via free radical grafting. These procedures are discussed in greater detail herinbelow.
The reaction with the heterocycle precursor is conducted at temperatures ranging from about 100xc2x0 C. to about 250xc2x0 C. preferably from about 120xc2x0 C. to about 180xc2x0 C., and occasionally from about 180xc2x0 C. to about 225xc2x0 C. for a sufficient time to convert at least about 50% of the carboxylic groups to heterocyclic groups.
One or both steps of the process may be conducted in the presence of a diluent, usually an oil of lubricating viscosity. Other diluents may be used; particularly if it is desired to remove the diluent before further use of the product. Such other diluents include relatively low boiling point liquids such as hydrocarbon solvents and the like.
The process may be conducted in a kettle type reactor. Under these conditions, it is frequently advantageous to utilize a diluent to improve processing. Alternatively, other reactors may be used. In one particular embodiment, the reactor is an extruder. Usually, processing in an extruder does not require the use of a diluent, although a diluent may be used if desired. It is not necessary that both steps of the process be conducted in the same type of reactor.
(P) The Hydrocarbon Polymer
As used herein, the expression xe2x80x98polymerxe2x80x99 refers to polymers of all types, i.e., homopolymers and copolymers. The term homopolymer refers to polymers derived from essentially one monomeric species; copolymers are defined herein as being derived from 2 or more monomeric species.
The hydrocarbon polymer is an essentially hydrocarbon based polymer, usually one having a number average molecular weight ({overscore (M)}n) between 20,000 and about 500,000, often from 20,000 to about 300,000, frequently from about 40,000 to about 200,000. Molecular weights of the hydrocarbon polymer are determined using well known methods described in the literature. Examples of procedures for determining the molecular weights are gel permeation chromatography (GPC) (also known as size-exclusion chromatography) and vapor phase osmometry (VPO). These and other procedures are described in numerous publications including:
P. J. Flory, xe2x80x9cPrinciples of Polymer Chemistryxe2x80x9d, Cornell University Press (1953), Chapter VII, pp. 266-316,
xe2x80x9cMacromolecules, an Introduction to Polymer Sciencexe2x80x9d, F. A. Bovey and F. H. Winslow, Editors, Academic Press (1979), pp. 296-312, and
W. W. Yau, J. J. Kirkland and D. D. Bly, xe2x80x9cModern Size Exclusion Liquid Chromatographyxe2x80x9d, John Wiley and Sons, New York, 1979.
Unless otherwise indicated, GPC molecular weights referred to herein are polystyrene equivalent weights, i.e., are molecular weights determined employing polystyrene standards.
A measurement which is complementary to a polymer""s molecular weight is the melt index (ASTM D-1238). Polymers of high melt index generally have low molecular weight, and vice versa. The polymers of the present invention preferably have a melt index of up to 20 dg/min., more preferably 0.1 to 10 dg/min.
These publications are hereby incorporated by reference for relevant disclosures contained therein relating to the determination of molecular weight.
When the molecular weight of a polymer is greater than desired, it may be reduced by techniques known in the art. Such techniques include mechanical shearing of the polymer employing masticators, ball mills, roll mills, extruders and the like. Oxidative or thermal shearing or degrading techniques are also useful and are known. Details of numerous procedures for shearing polymers are given in U.S. Pat. No. 5,348,673 which is hereby incorporated herein by reference for relevant disclosures in this regard. Reducing molecular weight also tends to improve the subsequent shear stability of the polymer.
The polymer may contain aliphatic, aromatic or cycloaliphatic components, or mixtures thereof. When the polymer is prepared from the monomers, it may contain substantial amounts of olefinic unsaturation, oftentimes far in excess of that which is desired for this invention. The polymer may be subjected to hydrogenation to reduce the amount of unsaturation to such an extent that the resulting hydrogenated polymer has olefinic unsaturation, based on the total number of carbon to carbon bonds in the polymer, of less than 5%, frequently less than 2%, often no more than 1% olefinic unsaturation.
In one embodiment, the polymer (P) is substantially saturated. In this case the reaction with (M) is conducted employing a free radical initiator. Such processes and products are described in U.S. Pat. Nos. 5,512,192 and 5,540,851 which are incorporated herein by reference.
In another embodiment, the polymer (A) contains olefinic unsaturation and the reaction is conducted thermally, employing the well known xe2x80x9cenexe2x80x9d process, optionally in the presence of added chlorine. The use of added chlorine during the reaction typically facilitates the reaction. Nonetheless, in order to avoid the presence of chlorine in the grafted product and derivatives thereof, it is preferred to conduct the grafting reaction thermally or in the presence of a free radical initiator.
The xe2x80x9cenexe2x80x9d process is described in the literature, for example in U.S. Pat. No. 3,412,111 and Ben et al, xe2x80x9cThe Ene Reaction of Maleic Anhydride With Alkenesxe2x80x9d, J. C. S Perkin 11 (1977), pp. 535-537, both of which are incorporated herein by reference for relevant disclosures contained therein.
Chlorine assisted grafting is described in numerous patents including U.S. Pat. Nos. 3,215,707; 3,912,764; and 4,234,435, which are incorporated herein by reference.
Typically, from about 90 to about 99.9% of carbon to carbon bonds in the polymer are saturated. As noted, the choice of grafting procedure typically depends upon the extent of olefinic unsaturation present in the polymer (P). Free radical initiators are typically used when the polymer is substantially saturated; the thermal xe2x80x9cenexe2x80x9d process may also be used when the polymer contains significant amounts of olefinic unsaturation.
Aromatic unsaturation is not considered olefinic unsaturation within the context of this invention. Depending on hydrogenation conditions, up to about 20% of aromatic groups may be hydrogenated; however, typically no more than about 5%, usually less than 1% of aromatic bonds are hydrogenated. Most often, substantially none of the aromatic bonds are hydrogenated.
In one typical embodiment, (P) the polymer contains an average of from 1 to about 9000 olefinic double bonds, more often from about 1 to about 100 olefinic double bonds, even more often from about 1, frequently 2 to about 10, up to about 50 olefinic double bonds per molecule based on the {overscore (M)}n of the polymer. In another embodiment, (P) contains about 1 olefinic double bond for about every 20, often for about every 70 to 7000 carbon atoms. In still another-embodiment, the hydrocarbon polymer (P) contains about 1 olefinic double bond for every 4,000 to 20,000 on {overscore (M)}n basis, often, about 1 olefinic double bond per 1,000 to 40,000 on {overscore (M)}n basis. Thus, for example, in this embodiment a polymer of {overscore (M)}n=80,000 would contain from about 2 to about 80 olefinic double bonds per molecule, often from about 4 to about 20 double bonds per molecule. In yet another embodiment, the hydrocarbon polymer (P) contains about 1 olefinic double bond for about every 300 to 100,000 on {overscore (M)}n basis.
As noted hereinabove, in another embodiment, the polymer is substantially saturated, as defined hereinabove.
The equivalent weight per mole of carbon to carbon double bonds is defined herein as the mole-equivalent weight. For example, a polymer having {overscore (M)}n of 100,000 and which contains an average of 4 moles of carbon to carbon double bonds, has a mole equivalent weight of 100,000/4=25,000. Conversely, the polymer has one mole of carbon to carbon double bonds per 25,000 {overscore (M)}n.
In preferred embodiments, the hydrocarbon polymer is at least one oil soluble or dispersible homopolymer or copolymer selected from the group consisting of:
(1) polymers of dienes;
(2) copolymers of conjugated dienes with vinyl substituted aromatic compounds;
(3) polymers of aliphatic olefins having from 2 to about 28 carbon atoms;
(4) olefin-diene copolymers; and
(5) star polymers.
These preferred polymers are described in greater detail hereinbelow.
(1) Polymers of Dienes
The hydrocarbon polymer may be a homopolymer or copolymer of one or more dienes. The dienes may be conjugated such as isoprene, butadiene and piperylene or non-conjugated such as 1-4 hexadiene, ethylidene norbomene, vinyl norbomene, 4-vinyl cyclohexene, and dicyclopentadiene. Polymers of conjugated dienes are preferred. Such polymers are conveniently prepared via free radical and anionic polymerization techniques. Emulsion techniques are commonly employed for free radical polymerization.
As noted hereinabove, useful polymers have {overscore (M)}n ranging from 20,000 to about 500,000. More often, useful polymers of this type have {overscore (M)}n ranging from about 50,000 to about 150,000.
These polymers may be and often are hydrogenated to reduce the amount of olefinic unsaturation present in the polymer. They may or may not be exhaustively hydrogenated. Hydrogenation is often accomplished employing catalytic methods. Catalytic techniques employing hydrogen under high pressure and at elevated temperature are well-known to those skilled in the chemical art. Other methods are also useful and are well known to those skilled in the art.
Extensive discussions of diene polymers appear in the xe2x80x9cEncyclopedia of Polymer Science and Engineeringxe2x80x9d, Volume 2, pp. 550-586 and Volume 8, pp. 499-532, Wiley-Interscience (1986), which are hereby expressly incorporated herein by reference for relevant disclosures in this regard.
The polymers include homopolymers and copolymers of conjugated dienes including polymers of 1,3-dienes of the formula
wherein each substituent denoted by R, or R with a numerical subscript, is independently hydrogen or hydrocarbon based, wherein hydrocarbon based is as defined hereinabove. Preferably at least one substituent is H. Normally, the total carbon content of the diene will not exceed 20 carbons. Preferred dienes for preparation of the polymer are piperylene, isoprene, 2,3-dimethyl-1,3-butadiene, chloroprene and 1,3-butadiene.
Suitable homopolymers of conjugated dienes are described, and methods for their preparation are given in numerous U.S. patents, including the following:
U.S. Pat. No. 3,547,821
U.S. Pat. No. 3,835,053
U.S. Pat. No. 3,959,161
U.S. Pat. No. 3,965,019
U.S. Pat. No. 4,085,055
U.S. Pat. No. 4,116,917.
As a specific example, U.S. Pat. No. 3,959,161 teaches the preparation of hydrogenated polybutadiene. In another example, upon hydrogenation, 1,4-polyisoprene becomes an alternating copolymer of ethylene and propylene.
Copolymers of conjugated dienes are prepared from two or more conjugated dienes. Useful dienes are the same as those described in the preparation of homopolymers of conjugated dienes hereinabove. The following U.S. Patents describe diene copolymers and methods for preparing them:
U.S. Pat. No. 3,965,019
U.S. Pat. No. 4,073,737
U.S. Pat. No. 4,085,055
U.S. Pat. No. 4,116,917
For example, U.S. Pat. No. 4,073,737 describes the preparation and hydrogenation of butadiene-isoprene copolymers.
(2) Copolymers of Conjugated Dienes with Vinyl Substituted Aromatic Compounds
In one embodiment, the hydrocarbon polymer is a copolymer of a vinyl-substituted aromatic compound and a conjugated diene. The vinyl substituted aromatics generally contain from 8 to about 20 carbons, preferably from 8 to 12 carbon atoms and most preferably, 8 or 9 carbon atoms.
Examples of vinyl substituted aromatics include vinyl anthracenes, vinyl naphthalenes and vinyl benzenes (styrenic compounds). Styrenic compounds are preferred, examples being styrene, alpha-methystyrene, ortho-methyl styrene, meta-methyl styrene, para-methyl styrene, para-tertiary-butylstyrene and clorostyrene, with styrene being preferred.
The conjugated dienes generally have from 4 to about 10 carbon atoms and preferably from 4 to 6 carbon atoms. Example of conjugated dienes include piperylene, 2,3-dimethyl-1,3-butadiene, chloroprene, isoprene and 1,3-butadiene, with isoprene and 1,3-butadiene being particularly preferred. Mixtures of such conjugated dienes are useful.
The vinyl substituted aromatic content of these copolymers is typically in the range of about 20% to about 70% by weight, preferably about 40% to about 60% by weight. The aliphatic conjugated diene content of these copolymers is typically in the range of about 30% to about 80% by weight, preferably about 40% to about 60% by weight.
The polymers, and in particular, styrene-diene copolymers, can be random copolymers or block copolymers, which include regular block copolymers or random block copolymers. Random copolymers are those in which the commoners are randomly, or nearly randomly, arranged in the polymer chain with no significant blocking of homopolymer of either monomer. Regular block copolymers are those in which a small number of relatively long chains of homopolymer of one type of monomer are alternately joined to a small number of relatively long chains of homopolymer of another type of monomer. Random block copolymers are those in which a larger number of relatively short segments of homopolymer of one type of monomer alternate with relatively short segments of homopolymer of another monomer.
The random, regular block and random block polymers used in this invention may be linear, or they may be partially or highly branched. The relative arrangement of homopolymer segments in a linear regular block or random block polymer is obvious. Differences in structure lie in the number and relative sizes of the homopolymer segments; the arrangement in a linear block polymer of either type is always alternating in homopolymer segments.
Normal or regular block copolymers usually have from 1 to about 5, often 1 to about 3, preferably only from 1 to about 2 relatively large homopolymer blocks of each monomer. Thus, a linear regular diblock copolymer of styrene or other vinyl aromatic monomer (S) and diene (D) would have a general structure represented by a large block of homopolymer (S) attached to a large block of homopolymer (D), as:
(S)s(D)d
where subscripts s and d are as described hereinbelow. Similarly, a regular linear tri-block copolymer of styrene or other vinyl aromatic monomer (S) and diene monomer (D) may be represented, for example, by
(S)s(D)d(S)s or (D)d(S)s(D)d.
Techniques vary for the preparation of these xe2x80x9cS-D-Sxe2x80x9d and xe2x80x9cD-S-Dxe2x80x9d triblock polymers, and are described in the literature for anionic polymerization.
A third monomer (T) may be incorporated into linear, regular block copolymers. Several configurations are possible depending on how the homopolymer segments are arranged with respect to each other. For example, linear triblock copolymers of monomers (S), (D) and (T) can be represented by the general configurations:
(S)s-(D)d-(T)t, (S)s-(T) t-(D)d, or (D)d-(S)s-(T)t,
wherein the lower case letters s, d and t represent the approximate number of monomer units in the indicated block.
The sizes of the blocks are not necessarily the same, but may vary considerably. The only stipulation is that any regular block copolymer comprises relatively few, but relatively large, alternating homopolymer segments.
As an example, when (D) represents blocks derived from diene such as isoprene or butadiene, xe2x80x9cdxe2x80x9d usually ranges from about 100 to about 2000, preferably from about 500 to about 1500; when (S) represents, for example, blocks derived from styrene, xe2x80x9csxe2x80x9d usually ranges from about 100 to about 2000, preferably from about 200 to about 1000; and when a third block (T) is present, xe2x80x9ctxe2x80x9d usually ranges from about 10 to about 1000, provided that the {overscore (M)}n of the polymer is within the ranges indicated as useful for this invention.
The copolymers can be prepared by methods well known in the art. Such copolymers usually are prepared by anionic polymerization using Group Ia metals in the presence of electron-acceptor aromatics, or preformed organometallics such as sec-butyllithium as polymerization catalysts.
The styrene/diene block polymers are usually made by anionic polymerization, using a variety of techniques, and altering reaction conditions to produce the most desirable features in the resulting polymer. In an anionic polymerization, the initiator can be either an organometallic material such as an alkyl lithium, or the anion formed by electron transfer from a Group Ia metal to an aromatic material such as naphthalene. A preferred organometallic material is an alkyl lithium such as sec-butyl lithium; the polymerization is initiated by addition of the butyl anion to either the diene monomer or to the styrene.
When an alkyl lithium initiator is used, a homopolymer of one monomer, e.g., styrene, can be selectively prepared, with each polymer molecule having an anionic terminus, and lithium gegenion. The carbanionic terminus remains an active initiation site toward additional monomers. The resulting polymers, when monomer is completely depleted, will usually all be of similar molecular weight and composition, and the polymer product will be xe2x80x9cmonodispersexe2x80x9d (i.e., the ratio of weight average molecular weight to number average molecular weight is very nearly 1.0). At this point, addition of 1,3-butadiene, isoprene or other suitable anionically polymerizable monomer to the homopolystyrene-lithium xe2x80x9clivingxe2x80x9d polymer produces a second segment which grows from the terminal anion site to produce a living di-block polymer having an anionic terminus, with lithium gegenion.
Subsequent introduction of additional styrene can produce a new poly S-block-poly D-block-poly S, or S-D-S triblock polymer; higher orders of block polymers can be made by consecutive stepwise additions of different monomers in different sequences.
Alternatively, a living diblock polymer can be coupled by exposure to an agent such as a dialkyl dichlorosilane. When the carbanionic xe2x80x9cheadsxe2x80x9d of two S-D diblock living polymers are coupled using such an agent, precipitation of LiCl occurs to give an S-D-S triblock polymer.
Block copolymers made by consecutive addition of styrene to give a relatively large homopolymer segment (S), followed by a diene to give a relatively large homopolymer segment (D), are referred to as poly-S-block-poly-D copolymers, or S-D diblock polymers.
When metal naphthalide is employed as initiator, the dianion formed by electron transfer from metal, e.g., Na, atoms to the naphthalene ring can generate dianions which may initiate polymerization, e.g. of monomer S, in two directions simultaneously, producing essentially a homopolymer of S having anionic termini at both ends.
Subsequent exposure of the poly (S) dianion to a second monomer (D) results in formation of a poly D-block-poly S-block-poly D, or a D-S-D triblock polymeric dianion, which may continue to interact with additional anionically-polymerizable monomers of the same, or different chemical type, in the formation of higher order block polymers. Ordinary block copolymers are generally considered to have up to about 5 such blocks.
Usually, one monomer or another in a mixture will polymerize faster, leading to a segment that is richer in that monomer, interrupted by occasional incorporation of the other monomer. This can be used to build a type of polymer referred to as a xe2x80x9crandom block polymerxe2x80x9d, or xe2x80x9ctapered block polymerxe2x80x9d. When a mixture of two different monomers is anionically polymerized in a non-polar paraffinic solvent, one will initiate selectively, and usually polymerize to produce a relatively short segment of homopolymer. Incorporation of the second monomer is inevitable, and this produces a short segment of different structure. Incorporation of the first monomer type then produces another short segment of that homopolymer, and the process continues, to give a xe2x80x9crandomxe2x80x9d alternating distribution of relatively short segments of homopolymers, of different lengths. Random block polymers are generally considered to be those comprising more than 5 such blocks. At some point, one monomer will become depleted, favoring incorporation of the other, leading to ever longer blocks of homopolymer, resulting in a xe2x80x9ctapered block copolymer.xe2x80x9d
An alternative way of preparing random or tapered block copolymers involves initiation of styrene, and interrupting with periodic, or step, additions of diene monomer. The additions are programmed according to the relative reactivity ratios and rate constants of the styrene and particular diene monomer.
xe2x80x9cPromotersxe2x80x9d are electron-rich molecules that facilitate anionic initiation and polymerization rates while lessening the relative differences in rates between various monomers. Promoters also influence the way in which diene monomers are incorporated into the block polymer, favoring 1,2-polymerization of dienes over the normal 1,4-cis-addition.
These polymers may have considerable olefinic unsaturation, which may be reduced, if desired. Hydrogenation to reduce the extent of olefinic unsaturation may be carried out to reduce approximately 90-99.1% of the olefinic unsaturation of the initial polymer, such that from about 90 to about 99.9% of the carbon to carbon bonds of the polymer are saturated. In general, it is preferred that these copolymers contain no more than about 10%, preferably no more than 5% and often no more than about 0.5% residual olefinic unsaturation on the basis of the total amount of olefinic double bonds present in the polymer prior to hydrogenation. Unsaturation can be measured by a number of means well known to those of skill in the art, including infrared, nuclear magnetic resonance spectroscopy, bromine number, iodine number, and other means. Aromatic unsaturation is not considered to be olefinic unsaturation within the context of this invention.
Hydrogenation techniques are well known to those of skill in the art. One common method is to contact the copolymers with hydrogen, often at superatmospheric pressure in the presence of a metal catalyst such as colloidal nickel, palladium supported on charcoal, etc. Hydrogenation may be carried out as part of the overall production process, using finely divided, or supported, nickel catalyst. Other transition metals may also be used to effect the transformation. Other techniques are known in the art.
Other polymerization techniques such as emulsion polymerization can be used.
Often the arrangement of the various homopolymer blocks is dictated by the reaction conditions such as catalyst and polymerization characteristics of the monomers employed. Conditions for modifying arrangement of polymer blocks are well known to those of skill in the polymer art. Literature references relating to polymerization techniques and methods for preparing certain types of block polymers include:
1) xe2x80x9cEncyclopedia of Polymer Science and Engineeringxe2x80x9d, Wiley-Interscience Publishing, New York, (1986);
2) A. Noshay and J. E. McGrath, xe2x80x9cBlock Copolymersxe2x80x9d, Academic Press, New York, (1977);
3) R. J. Ceresa, ed., xe2x80x9cBlock and Graft Copolymerizationxe2x80x9d, John Wiley and Sons, New York, (1976); and
4) D. J. Meier, ed., (Block Copolymersxe2x80x9d, MMI Press, Harwood Academic Publishers, New York, (1979).
Each of these is hereby incorporated herein by reference for relevant disclosures relating to block copolymers.
Examples of suitable commercially available regular linear diblock copolymers as set forth above include Shellvis-40, and Shellvis-50, both hydrogenated styrene-isoprene block copolymers, manufactured by Shell Chemical.
Examples of commercially available random block and tapered block copolymers include the various Glissoviscal styrene-butadiene copolymers manufactured by BASF. A previously available random block copolymer was Phil-Ad viscosity improver, manufactured by Phillips Petroleum.
The copolymers preferably have {overscore (M)}n in the range of 20,000 to about 500,000, more preferably from about 30,000 to about 150,000. The weight average molecular weight ({overscore (M)}w) for these copolymers is generally in the range of about 50,000 to about 500,000, preferably from about 50,000 to about 300,000.
Copolymers of conjugated dienes with olefins containing aromatic groups, e.g., styrene, methyl styrene, etc. are described in numerous patents including the following:
For example, U.S. Pat. No. 3,554,911 describes a random butadiene-styrene copolymer, its preparation and hydrogenation.
(3) Polymers of Aliphatic Olefins
Another useful hydrocarbon polymer is one which in its main chain is composed essentially of aliphatic olefin, especially alpha olefin, monomers. The polyolefins of this embodiment thus exclude polymers which have a large component of other types of monomers copolymerized in the main polymer, such as ester monomers, acid monomers, and the like. The polyolefin may contain impurity amounts of such materials, e.g., less than 5% by weight, more often less than 1% by weight, preferably, less than 0.1% by weight of other monomers. Useful polymers include oil soluble or dispersible polymers of alpha-olefins.
The olefin copolymer preferably has a number average molecular weight ({overscore (M)}n) determined by gel-permeation chromatography employing polystyrene standards, ranging from 20,000 to about 500,000, often from about 30,000 to about 300,000, often to about 200,000, more often from about 50,000 to about 150,000, even more often from about 80,000 to about 150,000. Exemplary polydispersity values ({overscore (M)}w/{overscore (M)}n) range from about 1.5 to about 3.5, often to about 3.0, preferably, from about 1.7, often from about 2.0, to about 2.5.
These polymers are preferably polymers of alpha-olefins having from 2 to about 28 carbon atoms. Preferably they are copolymers, more preferably copolymers of ethylene and at least one other xcex1-olefin having from 3 to about 28 carbon atoms, i.e., one of the formula CH2xe2x95x90CHR1 wherein R1 is straight chain or branched chain alkyl radical comprising 1 to 26 carbon atoms. Examples include monoolefins such as propylene, 1-butene, isobutene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, etc. Preferably R1 in the above formula is alkyl of from 1 to 8 carbon atoms, and more preferably is alkyl of from 1 to 2 carbon atoms. Preferably, the polymer of olefins is an ethylene-propylene copolymer.
The ethylene content is preferably in the range of 20 to 80 percent by weight, and more preferably 30 to 70 percent by weight. When propylene and/or 1-butene are employed as comonomer(s) with ethylene, the ethylene content of such copolymers is most preferably 45 to 65 percent, although higher or lower ethylene contents may be present. Most preferably, these polymers are substantially free of ethylene homopolymer, although they may exhibit a degree of crystallinity due to the presence of small crystalline polyethylene segments within their microstructure.
In one particular embodiment, the polymer is a homopolymer derived from a butene, particularly, isobutylene. Especially preferred is where the polymer comprises terminal vinylidene olefinic double bonds.
The polymers employed in this embodiment may generally be prepared substantially in accordance with procedures which are well known in the art.
Catalysts employed in the production of the reactant polymers are likewise well known. One broad class of catalysts particularly suitable for polymerization of a-olefins, comprises coordination catalysts such as Ziegler or Ziegler-Natta catalysts comprising a transition metal atom. Ziegler-Natta catalysts are composed of a combination of a transition metal atom with an organo aluminum halide and may be used with additional complexing agents.
Other useful polymerization catalysts are the metallocene compounds. These are organometallic coordination compounds obtained as cyclopentadienyl derivatives of a transition metal or metal halide. The metal is bonded to the cyclopentadienyl ring by electrons moving in orbitals extending above and below the plane of the ring (xcfx80 bond). The use of such materials as catalysts for the preparation of ethylene-alpha olefin copolymers is described in U.S. Pat. No. 5,446,221. The procedure described therein provides ethylene-alpha olefin copolymers having at least 30% of terminal ethenylidene unsaturation. This patent is hereby incorporated herein by reference for relevant disclosures.
Polymerization using coordination catalysis is generally conducted at temperatures ranging between 20xc2x0 and 300xc2x0 C., preferably between 30xc2x0 and 200xc2x0 C. Reaction time is not critical and may vary from several hours or more to several minutes or less, depending upon factors such as reaction temperature, the monomers to be copolymerized, and the like. One of ordinary skill in the art may readily obtain the optimum reaction time for a given set of reaction parameters by routine experimentation. Preferably, the polymerization will generally be completed at a pressure of 1 to 40 MPa (10 to 400 bar).
The polymerization may be conducted employing liquid monomer, such as liquid propylene, or mixtures of liquid monomers (such as mixtures of liquid propylene and 1-butene), as the reaction medium. Alternatively, polymerization may be accomplished in the presence of a hydrocarbon inert to the polymerization such as butane, pentane, isopentane, hexane, isooctane, decane, toluene, xylene, and the like.
When carrying out the polymerization in a batch-type fashion, the reaction diluent (if any) and the alpha-olefin comonomer(s) are charged at appropriate ratios to a suitable reactor. Care should be taken that all ingredients are dry, with the reactants typically being passed through molecular sieves or other drying means prior to their introduction into the reactor. Subsequently, component(s) of the catalyst are introduced while agitating the reaction mixture, thereby causing polymerization to commence. Alternatively, component(s) of the catalyst may be premixed in a solvent and then fed to the reactor. As polymer is being formed, additional monomers may be added to the reactor. Upon completion of the reaction, unreacted monomer and solvent are either flashed or distilled off, if necessary by vacuum, and the copolymer withdrawn from the reactor.
The polymerization may be conducted in a continuous manner by simultaneously feeding the reaction diluent (if employed), monomers, component(s) of the catalyst to a reactor and withdrawing solvent, unreacted monomer and polymer from the reactor so as to allow a residence time of ingredients long enough for forming polymer of the desired molecular weight; and separating the polymer from the reaction mixture.
In those situations wherein the molecular weight of the polymer product that would be produced at a given set of operating conditions is higher than desired, any of the techniques known in the prior art for control of molecular weight, such as polymerization temperature control, may be used.
The polymers are preferably formed in the substantial absence of added H2 gas, that is H2 gas added in amounts effective to substantially reduce the polymer molecular weight.
The polymers can be random copolymers, block copolymers, and random block copolymers. Ethylene propylene copolymers are usually random copolymers. Block copolymers may be obtained by conducting the reaction in a tubular reactor. Such a procedure is described in U.S. Pat. No. 4,804,794 which is hereby incorporated by reference for relevant disclosures in this regard.
Numerous United States patents, including the following, describe the preparation of copolymers of alpha olefins.
Copolymers of ethylene with higher alpha olefins are the most common copolymers of aliphatic olefins. Ethylene-propylene copolymers are the most common ethylene-alpha-olefin copolymers and are preferred for use in this invention. A description of an ethylene-propylene copolymer appears in U.S. Pat. No. 4,137,185 which is hereby incorporated herein by reference.
Useful ethylene-alpha olefin, usually ethylene-propylene, copolymers are commercially available from numerous sources including the Exxon, Texaco and Lubrizol Corporations.
(4) Olefin-Diene Copolymers
Another useful hydrocarbon polymer is one derived from olefins, especially lower olefins, and dienes. Preferred olefins are alpha olefins. Dienes may be non-conjugated or conjugated, usually non-conjugated. Useful olefins and dienes are the same as those described hereinabove and hereinafter in discussions of other polymer types.
In one embodiment, the copolymer is an ethylene-lower olefin-diene copolymer. As used herein, the term lower refers to groups or compounds containing no more than 7 carbon atoms. Preferably, the diene is non-conjugated. Especially preferred are ethylene-propylene-diene copolymers.
These copolymers most often will have {overscore (M)}n ranging from 20,000 to about 500,000, preferably from about 50,000 to about 200,000. In another embodiment, the {overscore (M)}n ranges from about 70,000 to about 350,000. These polymers often have a relatively narrow range of molecular weight as represented by the polydispersity value {overscore (M)}w/{overscore (M)}n. Typically, the polydispersity values are less than 10, more often less than 6, and preferably less than 4, often between 2 and 3.
There are numerous commercial sources for lower olefin-diene copolymers. For example, Ortholeum(copyright) 2052 (a product marketed by the DuPont Company) which is a terpolymer having an ethylene:propylene weight ratio of about 57:43 and containing 4-5 weight % of groups derived from 1,4-hexadiene monomer. Other commercially available olefin-diene copolymers including ethylene-propylene copolymers with ethylidene norbomene, with dicyclopentadiene, with vinyl norbornene, with 4-vinyl cyclohexene, and numerous other such materials are readily available. Olefin-diene copolymers and methods for their preparation are described in numerous patents including the following U.S. Patents:
U.S. Pat. No. 3,291,780
U.S. Pat. No. 3,300,459
U.S. Pat. No. 3,598,738
U.S. Pat. No. 4,026,809
U.S. Pat. No. 4,032,700
U.S. Pat. No. 4,156,061
U.S. Pat. No. 3,320,019
U.S. Pat. No. 4,357,250
U.S. Pat. No. 3,598,738, which describes the preparation of ethylene-propylene-1,4-hexadiene terpolymers, is illustrative. This patent also lists numerous references describing the use of various polymerization catalysts.
Another useful polymer is an olefin-conjugated diene copolymer. An example of such a polymer is butyl rubber, an isobutylene-isoprene copolymer.
Details of various types of polymers, reaction conditions, physical properties, and the like are provided in the above patents and in numerous books, including:
xe2x80x9cRiegel""s Handbook of Industrial Chemistryxe2x80x9d, 7th edition, James A. Kent Ed., Van Nostrand Reinhold Co., New York (1974), Chapters 9 and 10,
P. J. Flory, xe2x80x9cPrinciples of Polymer Chemistryxe2x80x9d, Cornell University Press, Ithaca, N.Y. (1953),
xe2x80x9cKirk-Othmer Encyclopedia of Chemical Technologyxe2x80x9d, 3rd edition, Vol. 8 (Elastomers, Synthetic, and various subheadings thereunder), John Wiley and Sons, New York (1979).
Each of the above-mentioned books and patents is hereby expressly incorporated herein by reference for relevant disclosures contained therein.
Polymerization can also be effected using free radical initiators in a well-known process, generally employing higher pressures than used with coordination catalysts. These polymers may be and frequently are hydrogenated to bring unsaturation to desired levels. As noted, hydrogenation may take place before or after reaction with the carboxylic reactant.
(5) Star Polymer
Star polymers are polymers comprising a nucleus and polymeric arms. Common nuclei include polyalkenyl compounds, usually compounds having at least two non-conjugated alkenyl groups, usually groups attached to electron withdrawing groups, e.g., aromatic nuclei. The polymeric arms are often homopolymers and copolymers of dienes, preferably conjugated dienes, vinyl substituted aromatic compounds such as monoalkenyl arenes, homopolymers of olefins such as butenes, especially isobutene, and mixtures thereof.
Molecular weights (GPC peak) of useful star polymers range from 20,000 to about 4 million. They frequently have {overscore (M)}n ranging from about 100,000 to about 2 million.
The polymers thus comprise a poly(polyalkenyl coupling agent) nucleus with polymeric arms extending outward therefrom. The star polymers are usually hydrogenated such that at least 80% of the olefinic carbon-carbon bonds are saturated, more often at least 90% and even more preferably, at least 95% are saturated. As noted herein, the polymers contain olefinic unsaturation; accordingly, they are not exhaustively saturated before reaction with the carboxylic reactant.
The polyvinyl compounds making up the nucleus are illustrated by polyalkenyl arenes, e.g., divinyl benzene and poly vinyl aliphatic compounds.
Dienes making up the polymeric arms are illustrated by butadiene, isoprene and the like. Monoalkenyl compounds include, for example, styrene and alkylated derivatives thereof. In one embodiment, the arms are derived from dienes. In another embodiment, the arms are derived from dienes and vinyl substituted aromatic compounds. In yet another embodiment, the arms comprise polyisobutylene groups. Arms derived from dienes or from dienes and vinyl substituted aromatic compounds are frequently substantially hydrogenated.
Star polymers are well known in the art. Such material and methods for preparing same are described in numerous publications and patents, including the following United States patents which are hereby incorporated herein by reference for relevant disclosures contained therein:
U.S. Pat. No. 4,116,917,
U.S. Pat. No. 4,141,847,
U.S. Pat. No. 4,346,193,
U.S. Pat. No. 4,358,565,
and U.S. Pat. No. 4,409,120.
Star polymers are commercially available, for example as Shellvis 200 sold by Shell Chemical Co.
Mixtures of two or more hydrocarbon polymers may be used.
In another embodiment, mixtures of one or more of the hydrocarbon polymers (P) with one or more other reactants, usually olefins other than hydrocarbon polymers included within the definition of reactant (P) of this invention, may be used. Such a mixture often comprises from about 0.1 mole equivalent to about 50% by weight of other reactant. In a particular embodiment, from about 0.1 mole equivalent of carbon to carbon double bonds to about 2 moles of an olefinically unsaturated compound having molecular weight ranging from about 100 to less than 20,000, often up to about 10,000, per mole equivalent of carbon to carbon double bonds in (P).
Examples include mixtures of any of the hydrocarbon polymers (P) with lower olefins, such as alpha-olefins containing up to about 100 carbon atoms, polyolefins, for example polyisobutylene, especially high vinylidene polyisobutylene, having molecular weights ranging from about 500 up to about 5,000, ethylene-propylene-diene compounds such as those identified by the tradename Trilene(copyright) and marketed by Uniroyal Chemical Co., and others.
(M) The xcex1,xcex2-Unsaturated Carboxylic Acid Or Functional Derivative Thereof
The xcex1,xcex2-unsaturated carboxylic acids or functional derivatives are well know in the art. The most commonly used materials contain from 2 to about 20 carbon atoms exclusive of carbonyl carbons. They include such acids as acrylic acid, methacrylic acid, maleic acid, fumaric acid, crotonic acid, citraconic acid, itaconic acid and mesaconic acid, as well as their anhydrides, halides and esters (especially the lower alkyl esters, the term xe2x80x9clower alkylxe2x80x9d meaning alkyl groups having up to 7 carbon atoms). The preferred compounds are the alpha-beta-olefinic carboxylic acids, especially those containing at least two carboxy groups and more especially dicarboxylic acids, and their derivatives. Maleic acid and maleic anhydride, especially the latter, are particularly preferred.
The intermediate prepared by the process of this invention is prepared by grafting, either by mastication of the neat polymer, or in solution, the xcex1,xcex2-unsaturated carboxylic acid or functional derivative onto the polymer employing techniques that are well-known in the art. Free-radical grafting techniques are usually employed. Thermal grafting by the xe2x80x9cenexe2x80x9d reaction using copolymers containing unsaturated sites, such as ethylene-propylene-diene copolymers may be employed.
Free Radical-Generating Reagents
Radical grafting is preferably carried out using free radical initiators such as peroxides, hydroperoxides, and azo compounds which decompose thermally within the grafting temperature range to provide said free radicals.
Free radical generating reagents are well know to those skilled in the art. Examples include benzoyl peroxide, t-butyl perbenzoate, t-butyl metachloroperbenzoate, t-butyl peroxide, sec-butylperoxydicarbonate, azobisisobutyronitrile, and the like. Numerous examples of free radical-generating reagents, also known as free-radical initiators, are mentioned in the above-referenced tests by Flory and by Bovey and Winslow. An extensive listing of free-radical initiators appears in J. Brandrup and E. H. Immergut, Editor, xe2x80x9cPolymer Handbookxe2x80x9d, 2nd edition, John Wiley and Sons, New York (1975), pages II-1 to II-40. Preferred free radical-generating reagents include t-butyl peroxide, t-butyl hydroperoxide, t-butyl perbenzoate, t-amyl peroxide, cumyl peroxide, t-butyl peroctoate, t-butyl-m-chloroperbenzoate and azobisisovaleronitrile.
The free-radical initiators are generally used in an amount from 0.01 to about 10 percent by weight based on the total weight of the reactants. Preferably, the initiators are used at about 0.05 to about 1 percent by weight.
The reaction is usually conducted at temperatures ranging between about 80xc2x0 C. to about 200xc2x0 C., preferably between about 130xc2x0 C. to about 170xc2x0 C. Considerations for determining reaction temperatures include reactivity of the system and the half-life of the initiator at a particular temperature.
The choice of free radical generating reagent can be an important consideration. For example, when a polymer undergoing grafting with a monomer is diluted with a solvent such as a hydrocarbon oil, grafting of the monomer onto the oil diluent may occur. It has been observed that the choice of initiator affects the extent of grafting of the monomer onto the oil diluent. Reducing the amount of monomer grafted onto the diluent usually results in an increased amount of monomer grafted onto the polymer. Improved efficiency of monomer grafting onto substantially saturated copolymer resins has been described by Lange et al. in U.S. Pat. No. 5,298,565 which is hereby incorporated herein by reference for relevant disclosures in this regard.
Azo group containing initiators, such as Vazo(copyright) polymerization initiators (DuPont) employed in the grafting process at about 95xc2x0 C. result in a much higher degree of grafting onto the polymer than do peroxide initiators such as t-butyl peroxide, employed at about 150-160xc2x0 C. Peresters are particularly effective in the free-radical grafting process.
(C) The Heterocycle Precursor
The compositions of this invention may be prepared by reacting the carboxylic group containing intermediate with a heterocycle precursor. These reactions generate the group xe2x80x98Bxe2x80x99 in the composition of formula (I). The heterocycle precursor is usually an acyclic reactant that cyclizes with the carboxylic group to form a heterocyclic compound. Materials which are useful as heterocycle precursors are compounds having the general formula
Hxe2x80x94W-alkylene-NH2 (II)
wherein each W is selected from O, S, and NRb, the xe2x80x98alkylenexe2x80x99 group contains from 1 to about 8 carbon atoms. preferably from about 2 to about 4 carbon atoms, and most preferably about 2, which carbon atoms may have one or more substituents selected from the group consisting of hydrocarbyl, hydroxyhydrocarbyl, and aminohydrocarbyl, wherein Rb is H, hydrocarbyl, hydroxyhydrocarbyl, or aminohydrocarbyl, and the general formula
or salts thereof, wherein V is H2Nxe2x80x94 or H2NNHxe2x80x94, and U is O, S or NH.
Illustrative of suitable reactants (II) are alkanolamines, mercaptoalkylene amines, and di- and polyamines. Specific examples include ethanolamine, 2-aminopropanol, 2-methyl-2-amino-propanol, tris(hydroxymethyl) aminomethane, 2-mercaptoethylamine, ethylene diamine, 1-amino-2-methylaminoethane, diethylenetriamine, triethylene tetramine, and analogous ethylene polyamines including amine bottoms and condensed amines such as those described hereinbelow, alkoxylated ethylene polyamines such as N-(2-hydroxyethyl) ethylene diamine, and others.
Alkylene polyamines, especially ethylene polyamines, such as some of those mentioned above, are preferred. They are described in detail under the heading xe2x80x9cDiamines and Higher Aminesxe2x80x9d in Kirk Othmer""s xe2x80x9cEncyclopedia of Chemical Technologyxe2x80x9d, 4th Edition, Vol. 8, pages 74-108, John Wiley and Sons, New York (1993) and in Meinhardt, et al, U.S. Pat. No. 4,234,435, both of which are hereby incorporated herein by reference for disclosure of useful polyamines. Such polyamines are conveniently prepared by the reaction of ethylene dichloride with ammonia or by reaction of an ethylene imine with a ring opening reagent such as water, ammonia, etc. These reactions result in the production of a complex mixture of polyalkylene polyamines including cyclic condensation products. The mixtures are particularly useful.
Other useful types of polyamine mixtures are those resulting from stripping of the above-described polyamine mixtures removing lower molecular weight polyamines and volatile components to leave as residue what is often termed xe2x80x9cpolyamine bottomsxe2x80x9d. In general, alkylene polyamine bottoms can be characterized as having less than 2%, usually less than 1% (by weight) material boiling below about 200xc2x0 C. In the instance of ethylene polyamine bottoms, which are readily available and found to be quite useful, the bottoms contain less than about 2% (by weight) total diethylene triamine (DETA) or triethylene tetramine (TETA). A typical sample of such ethylene polyamine bottoms obtained from the Dow Chemical Company of Freeport, Tex., designated xe2x80x9cE-100xe2x80x9d has a specific gravity at 15.6xc2x0 C. of 1.0168, a percent nitrogen by weight of 33.15 and a viscosity at 40xc2x0 C. of 121 centistokes. Gas chromatography analysis of such a sample showed it contains about 0.93% xe2x80x9cLight Endsxe2x80x9d (most probably diethylenetriamine), 0.72% triethylenetetramine, 21.74% tetraethylene pentamine and 76.61% pentaethylene hexamine and higher (by weight). These alkylene polyamine bottoms include cyclic condensation products such as piperazine and higher analogs of diethylenetriamine, triethylenetetramine and the like.
In another embodiment, the polyamines are hydroxy-containing polyamines provided that the polyamine contains at least one condensable xe2x80x94Nxe2x80x94H group. Hydroxy-containing polyamine analogs of hydroxy monoamines, particularly alkoxylated alkylenepolyamines can also be used. Typically, the hydroxyamines are primary or secondary alkanol amines or mixtures thereof. Such amines can be represented by mono- and poly-N-hydroxyalkyl substituted alkylene polyamines wherein the alkylene polyamines are as described hereinabove; especially those that contain two to three carbon atoms in the alkylene radicals and the alkylene polyamine contains up to seven amino groups. Such polyamines can be made by reacting the above-described alkylene amines with one or more alkylene oxides. Conditions for carrying out such reactions are known to those skilled in the art.
Another useful polyamine is a condensation product obtained by reaction of at least one hydroxy compound with at least one polyamine reactant containing at least one primary or secondary amino group. These condensation products are characterized as being a polyamine product having at least one condensable primary or secondary amino group, made by contacting at least one hydroxy-containing material (b-i) having the general formula
(R)nYzxe2x80x94Xpxe2x80x94(A(OH)q)mxe2x80x83xe2x80x83(I)
wherein each R is independently H or a hydrocarbon based group, Y is selected from the group consisting of O, N, and S, X is a polyvalent hydrocarbon based group, A is a polyvalent hydrocarbon based group, n is 1 or 2, z is 0 or 1, p is 0 or 1, q ranges from 1 to about 10, and m is a number ranging from 1 to about 10; with (b-ii) at least one amine having at least one Nxe2x80x94H group.
The hydroxy material (b-i) can be any hydroxy material that will condense with the amine reactants (b-ii). These hydroxy materials can be aliphatic, cycloaliphatic, or aromatic; monools and polyols. Aliphatic compounds are preferred, and polyols are especially preferred. Highly preferred are aminoalcohols, especially those containing more than one hydroxyl group. Typically, the hydroxy-containing material (b-i) contains from 1 to about 10 hydroxy groups.
The hydroxy compounds are preferably polyhydric alcohols and amines, preferably polyhydric amines. Polyhydric amines include any of the above-described monoamines reacted with an alkylene oxide (e.g., ethylene oxide, propylene oxide, butylene oxide, etc.) having two to about 20 carbon atoms, preferably 2 to about 4. Examples of polyhydric amines include tri-(hydroxypropyl)amine, tris-(hydroxymethyl)amino methane, 2-amino-2-methyl-1,3-propanediol, N,N,Nxe2x80x2,Nxe2x80x2-tetrakis(2-hydroxypropyl)ethylenediamine, and N,N,Nxe2x80x2,Nxe2x80x2-tetrakis(2-hydroxyethyl)ethylenediamine.
Among the preferred amines making up b(ii) are the alkylene polyamines, including the polyalkylene polyamines. In another embodiment, the polyamine may be a hydroxyamine provided that the polyamine contains at least one condensable xe2x80x94Nxe2x80x94H group. Preferred polyamine reactants include triethylenetetramine (TETA), tetraethylenepentamine (TEPA), pentaethylenehexamine (PEHA), and mixtures of polyamines such as the above-described xe2x80x9camine bottomsxe2x80x9d.
Preferred combinations of reactants for making the polyamine product include those in which reactant (b-i) is a polyhydric alcohol having three hydroxyl groups or an amino alcohol having two or more hydroxy groups and reactant (b-ii) is an alkylene polyamine having at least two primary nitrogen atoms and wherein the alkylene group contains 2 to about 10 carbon atoms.
The reaction is conducted in the presence of an acid catalyst at an elevated temperature. Catalysts useful for the purpose of this invention include mineral acids (mono, di- and poly basic acids) such as sulfuric acid and phosphoric acid; organophosphorus acids and organo sulfonic acids, alkali and alkaline earth partial salts of H3PO4 and H2SO4, such as NaHSO4, LiHSO4, KHSO4, NaH2PO4, LiH2PO4 and KH2PO4; CaHPO4, CaSO4 and MgHPO4; also Al2O3 and Zeolites. Phosphorus and phosphoric acids and their esters or partial esters are preferred. Also useful as catalysts are materials which generate acids when treated in the reaction mixture, e.g., trialkylphosphites. Catalysts are subsequently neutralized with a metal-containing basic material such as alkali metal, especially sodium, hydroxides.
The amine condensates and methods of making the same are described in Steckel (U.S. Pat. No. 5,053,152) which is incorporated by reference for its disclosure to the condensates and methods of making.
Illustrative heterocycle precursors (III) which may react with an acid or acid derivative group to form heterocycles are aminoguanidine and salts thereof, semicarbazide, thiosemicarbazide, carbohydrazide and thiocarbohydrazide, as well as salts thereof such as aminoguanidine bicarbonate. The cyclization reactions which take place are exemplified by those disclosed in Angewandte Chemie, International Edition, 2, 459 (1963); Organic Syntheses, Coll. Vol. III, 95 (1955); and Chemical Abstracts, 57, 804i (1962), which are incorporated by reference for such disclosures. They may be illustrated as follows:
Various other reactions may also form heterocycles. For example, the heterocycle or acyclic heterocycle precursor may react with an acid derivative such as an anhydride or ester. Also, a reaction may take place between an acid or acid derivative group and an active hydrogen-containing atom on the heterocycle formed from the acyclic heterocycle precursor; e.g., the 3-amino or ring NH group of a 3-amino-triazole.
Useful compositions of this invention may be prepared by reacting the carboxylic group containing intermediate with either of Hxe2x80x94W-alkylene-NH2 (II) and
or salts thereof. Alternatively, the carboxylic group containing intermediate is reacted with both of Hxe2x80x94W-alkylene-NH2 (II) and
simultaneously or consecutively in any order. When both of (II) and (III) are used, the typical reaction is with from about 20-40 mole % of (II) and from about 60-80 mole % of (III).
In yet another embodiment, the intermediate from the carboxylic acid or functional derivative thereof is reacted with both of at least one heterocycle precursor and at least one additional compound having at least one condensable Nxe2x80x94H group, simultaneously or consecutively, in any order.
The at least one additional compound is a reactant that does not form a heterocyclic group B under the conditions described herein.
In one embodiment, the additional compound is the reaction product of a hydrocarbyl substituted acid or anhydride having at least 30 carbon atoms in the hydrocarbyl group and an alkylene polyamine having 2 or 3 carbon atoms in each alkylene group. In another embodiment, the additional compound is a heterocyclic derivative of a fatty acid and an alkylene polyamine containing at least one nitrogen atom in the heterocyclic group.
Primary and secondary monoamines are useful additional compounds.
It is possible that the reaction of a carboxylic acid or derivative, such as the intermediate arising from reaction of the polymer (P) and the carboxylic reactant (M), with a heterocycle precursor may, under certain conditions, afford substantial proportions of a non-heterocyclic product. For example, reaction with ethylene diamine or monoethanolamine may generate an amide; with semicarbazide a group of formula
Non-heterocyclic groups of these kinds are included within the definition of the groups xe2x80x98Axe2x80x99 in the composition of Formula (I).
(D) The Hydrocarbyl Substituted Carboxylic Acid or Anhydride.
In still another embodiment, the reaction of the intermediate arising from reaction of (P) and (M) with the heterocycle precursor (C) is conducted, simultaneously or consecutively, with (D), at least one hydrocarbyl substituted carboxylic acid or anhydride. In this embodiment, typically from about 60% to about 80% of the heterocycle precursor is reacted with a hydrocarbyl substituted carboxylic acid or anhydride before reaction with the intermediate.
Reactant (D), a carboxylic acid or anhydride, may be mono- or polycarboxylic. Suitable carboxylic acids or anhydrides are hydrocarbyl substituted, preferably oil-soluble. These may be aromatic, cycloaliphatic and aliphatic acids. Preferably the hydrocarbyl substituent is aliphatic and contains at least 8 carbon atoms, more preferably at least about 30 carbon atoms. In another embodiment (D) comprises a mixture of hydrocarbyl substituted carboxylic acids or anhydrides wherein the mixture comprises aliphatic substituted carboxylic acids or anhydrides containing from about 12 to about 24 carbon atoms in the aliphatic substituent and aliphatic substituted carboxylic acids or anhydrides having at least about 40 carbon atoms in the aliphatic substituent.
Monocarboxylic acids have the formula RCOOH. R is a hydrocarbyl group, preferably an aliphatic group. Preferably, R contains from about 2 to about 500 carbon atoms. In one preferred embodiment, R is an aliphatic group containing from about 8 to about 24 carbon atoms, more often from about 12 to about 18 carbon atoms. Examples of such acids are caprylic, capric, palmitic, stearic, isostearic, oleic, linoleic, and behenic acids.
Another preferred group of monocarboxylic acids is prepared by the reaction of a polyolefin or a halogenated olefin polymer with acrylic acid or methacrylic acid.
Polycarboxylic acids may be illustrated by the general formula
Rxe2x80x94(COOH)m
wherein R is a hydrocarbyl group. R may be aliphatic or aromatic, including alkyl, alkenyl, aralkyl and alkaryl, including mixtures of acids containing aliphatic and aromatic groups. Preferably R is an aliphatic group, and preferably contains from about 5 to about 500 carbon atoms, more preferably from 16 to about 200 carbon atoms, even more preferably from about 30 to about 100 carbon atoms. The subscript xe2x80x98mxe2x80x99 is a number ranging from 2 to about 10, preferably 2 to about 4, more preferably 2 or 3. In an especially preferred embodiment m=2. Mixtures of such acids are also useful.
Patents describing useful aliphatic carboxylic acids or anhydrides and methods for preparing them include, among numerous others, U.S. Pat. No. 3,215,707 (Rense); U.S. Pat. No. 3,219,666 (Norman et al), U.S. Pat. No. 3,231,587 (Rense); U.S. Pat. No. 3,912,764 (Palmer); U.S. Pat. No. 4,110,349 (Cohen); and U.S. Pat. No. 4,234,435 (Meinhardt et al); and U.K. 1,440,219. These patents are hereby incorporated herein by reference for relevant disclosures contained therein.
In another preferred embodiment, the acid or anhydride (D) may contain from about 8 to 28 carbon atoms. When these are aliphatic acids, preferably predominantly linear acids, they tend to provide friction reducing characteristics to lubricating oils comprising the dispersant-viscosity improvers of this invention which incorporate such acids therein.
Another group of carboxylic reactants suitable as (D) comprises those obtained by reacting aldehydo- or keto-carboxylic acids and functional derivatives thereof with olefinic reactants having molecular weight ranging from about 100 to 20,000, preferably aliphatic mono olefins having from 30 to about 200 carbon atoms. Representative of such materials are products obtained by reacting polyisobutylene ({overscore (M)}nxcx9c1000) with glyoxylic acid or the methyl ester, methyl hemiacetal thereof. Representative materials are described in European (EP) patent publications 0759443; 0759444; and 0759435.
Further carboxylic reactants suitable as (D) are those obtained by reacting aldehydo- and keto-carboxylic acids and functional derivatives thereof with hydrocarbyl substituted, particularly C10-100 substituted hydroxy aromatic compounds, preferably phenols. Representative materials are described in U.S. Pat. Nos. 5,281,346; 5,356,546; and 5,336,278.
Other useful acids are hydrocarbyloxypolyoxyalkylenecarboxylic acids. Some examples of the hydrocarbyloxypolyoxyalkylenecarboxylic acids include: lauryl-Oxe2x80x94(CH2CH2O)2.5xe2x80x94CH2CO2H; lauryl-Oxe2x80x94CH2CH2O)3.3CH2CO2H; lauryl-Oxe2x80x94(C3H6O)x(CH2CH2O)yCH2CO2H, wherein x=2-3 and y=1-2, and 2-octadecanyl-Oxe2x80x94(CH2CH2O)6CH2CO2H. Additionally, polyether alpha, omega-acids, such as 3,6,9-trioxaundecane-1,11-dioic acid and mixed polyether diacids available from Hoechst Chemie can also be incorporated to impart surface activity and polarity, and to affect morphology at low temperatures.
In one embodiment, the hydrocarbyloxypolyalkyleneoxycarboxylic acid is stearyl, preferably isostearyl, pentaethyleneglycolacetic acid. Some of these acids are available commercially from Sandoz Chemical under the tradename Sandopan Acids.
Similar hydrocarbyloxypoly(alkyleneoxy) carboxylic acids derived from oxidation of C9-15 alcohol etherates are available from Shell Chemical under the tradename Neodox.
Other acids useful as (D) are aromatic acids such as benzoic, salicylic, hydroxynaphthoic and heterocyclic acids, for example, pyridine dicarboxylic acid and pyrrolidone-5-carboxylic acid.
Polyacids from vegetable- and animal-sourced carboxylic compounds can be used. Dimer acids, made by the thermal coupling of unsaturated vegetable acids, are available from Emery, Westvaco, Unichema and other companies. Polyacid reaction products of unsaturated vegetable acids with acrylic acid and maleic anhydride are available from Westvaco under the product names Diacid 1550 and Tenax 2010, respectively. Another useful vegetable derived acid is 12-hydroxystearic acid.
Preferred are carboxylic acids, including polyolefin substituted succinic acids, succinic anhydrides, ester acids or lactone acids.

Nitrogen containing dispersant-viscosity improvers

Abstract: wherein each X is independently O, S, or NRb, each Rb is independently H, NH2, hydrocarbyl, hydroxyhydrocarbyl, or aminohydrocarbyl, each s is independently 1 or 2, and each Z is independently a hydrocarbyl group, optionally substituted with one or more carboxylic acid groups or amide groups, each Ra is independently an ethylene group, a propylene group, which groups optionally have hydrocarbyl or hydroxyhydrocarbyl substituents, or


Methods and apparatus for determining whether a phone call is an inter-MTA or an intra-MTA call. Call detail records are retrieved that describe the call. An originating MTA is determined using the originating NPA/NXX, while the terminating MTA is determined using the terminating NPA/NXX. The determined originating MTA is compared with the determined terminating MTA to determine whether the phone call is an inter-MTA or an intra-MTA call.

In modern switched telecommunications systems (in particular, modern PSTNs) it has become common practice to provide two related but separate network infrastructures: a bearer or transmission network for carrying end-user voice and data traffic, and a signaling network for controlling the setup and release of bearer channels through the bearer network in accordance with control signals transferred through the signaling network. In practice, such signaling networks comprise high-speed computers interconnected by signaling links, wherein procedures control the computers to provide a set of operational and signaling functions in accordance with a standardized protocol. One example of such a signaling protocol is the Common Channel Signaling System No. 7 (i.e., SS7 or C7) which is being extensively deployed for control of telephone and other data transmission networks.
SS7 is a global standard for telecommunications defined by the International Telecommunication Union (ITU) Telecommunication Standardization Sector (ITU-T). The standard defines the procedures and protocol by which network elements in the public switched telephone network (PSTN) exchange information over a digital signaling network to effect wireless (cellular) and wireline call setup, routing and control. The ITU definition of SS7 allows for national variants such as the American National Standards Institute (ANSI) and Bell Communications Research (Telcordia Technologies) standards used in North America and the European Telecommunications Standards Institute (ETSI) standard used in Europe.
An SS7 network basically comprises various types of signaling points, namely, Signaling End Points (SEPs), for example an end office or local exchange, and Signaling Transfer Points (STPs) interconnected by signaling links, the SEPs being associated for example with respective Signaling Switching Points (SSPs) and Mobil Switching Centers (MSPs) of the transmission network, and with Service Control Points (SCPs).
The signaling information is passed over the signaling link in messages, which are called signal units (SUs). There are three types of SUs: message signal units (MSUs), link status signal units (LSSUs) and fill-in signal units (FISUs). The MSU is the workhorse in that signaling associated with call setup and tear down, database query and response, and SS& management is carried by Message Signal Units (MSUs). Know operations support systems (OSS systems), such as the AGILENT TECHNOLOGIES ACCESS7 system, extract data from the MSUs to generate Call detail Records (CDRs). The CDRs are analyzed by the OSS system to provide a variety of information about the SS7 network, for example: identification of signaling problems, location of network problems, service assurance data, and billing verification.
In fact, CDRs have proven extremely valuable for billing verification purposes. Analysis of CDRs can permit carriers to validate billing data to ensure that the charges they make are accurate and fair. For example, CDRs have been used to provide reports that distinguish the percentage of interstate traffic (billed at one rate) with intrastate traffic (billed at another rate). This percentage is known as the Percentage Interstate Usage (PIU). This has permitted local exchange carriers (LECS) to ensure that the charges to their associated inter-exchange carriers (IXCs) are accurate and visa-versa. Using the AGILENT TECHNOLOGIES ACCESS7 system, distinguishing between intrastate and interstate traffic is typically made using the Interconnect Analysis software. This software enriches the CDR information with information that assigns jurisdictional information to the CDR.
One area of development is billing solutions for calls that cross from wireless to wired communication system or visa-versa. As with any call, jurisdictional factors are used to determine the appropriate rates applied to such traffic. However, the geographical boundaries that LECs use to assign a jurisdiction is different from those used by WSPs. LECs use the Local Access and Transport Area (LATA) which divides the United States into 196 local geographical areas within which a LEC may offer service. For wireless traffic, the FCC has divided the country into geographic regions, termed Basic Trading Areas (BTAs), defined by a group of counties that surround a city, which is the area's basic trading center. The boundaries of each BTA are formulated by Rand McNally & Co. and are used by the FCC to determine service areas for PCS wireless license. BTAs are further grouped into Major Trading Areas (MTAs), once again formulated by Rand McNally & Co. These large areas are used by the FCC determine service areas for some PCS wireless licenses. The U.S. is divided into 51 MTAs. LECs and WSPs enter into agreement setting forth reciprocal payment schedules for calls that cross jurisdictions.
Under some interconnection agreements between LECs and WSPs, the WSP must make a compensation payment to the LEC at various rates for calls originating from a wireless device and terminating on a traditional landline device. The billing rates between the WSP and LEC are determined based on the originating MTA and terminating MTA. One rate exists for local traffic, defined as traffic originating and terminating within the same MTA, or IntraMTA. Another rate exists for non-local traffic, defined as traffic originating from one MTA and terminating within a second MTA, or InterMTA. With respect to LECs, known CDRs and methods of analysis associated therewith have proven adequate for verifying billing of land originated and terminated calls, but no solution exists for wireless originated and land terminated calls or vice-a-versa. The current practice for tracking such charges is for the WSP to provide a figure that represents a percentage of inter-MTA calls to the LEC. This number is used to determine the reciprocal compensation payments between the LEC and WSP. As the rate is based on MTA jurisdictions, many LECs are unable to verify the percentage of inter-MTA calls as reported by the WSP.
The present inventors have recognized a need for method and apparatus for reliably verifying the percentage of inter-MTA calls.

Apparatus and method to identify inter-MTA calls


A semiconductor device comprises a drift region of a first conduction type, a base region of a second conduction type, a source region of the first conduction type, a contact hole, a column region of the second conduction type, a plug and wiring. The drift region formed on a semiconductor substrate of the first conduction type. The base region of a second is formed in a prescribed region of the surface of the drift region. The source region is formed in a prescribed region of the surface of the base region. The contact hole extends from the source region surface side to the base region. The column region is formed in the drift region below the contact hole. The plug comprises a first conductive material and fills the contact hole. The wiring comprises a second conductive material and is electrically connected to the plug.

1. Field of the Invention
This invention relates to a semiconductor device and method for manufacturing same, and in particular relates to a MOS-type transistor with a high withstand voltage.
2. Description of the Related Art
Vertical-type power MOSFETs have been used as devices with high withstand voltages. Important characteristics of a vertical power MOSFET are the on-resistance (Ron) and the breakdown voltage (BVDSS). For a given breakdown voltage of a power MOSFET, a lower on-resistance means higher performance. There is a tradeoff between on-resistance Ron and breakdown voltage BVDSS. The on-resistance of a power MOSFET depends on the resistivity of the electric field relaxation layer (drift region).
FIG. 6 shows the structure of a typical vertical power MOSFET. In the power MOSFET shown in FIG. 6, a drift region 302, which is an electrical field relaxation layer of the same conduction type as the semiconductor substrate 301, is formed on the substrate. This drift region 302 is generally formed by epitaxial growth. A base region 308 is formed by ion implantation and thermal diffusion from the surface of the drift region 302. A conduction type of the base region 308 is opposite to that of the drift region 302. Further, a source region 309 is formed by ion implantation and thermal diffusion from the surface of the base region 308. A conduction type of the source region 309 is opposite to that of the base region 308.
A gate oxide film (gate insulating film) 306 is formed at the surface of the base region 308 between the source region 309 and the drift region 302 on the semiconductor surface. A gate electrode 307 is formed on the gate oxide film 306. A source electrode 311 is formed on the source region 309, and a drain electrode is formed on the rear surface of the semiconductor substrate. The semiconductor substrate 301 and drift region 302 are used as the drain of a MOS transistor. The channel is formed in the base region 308 below the gate oxide film.
In a power MOSFET with such a structure, when there is no gate-source bias applied to the power MOSFET and when a reverse drain-source bias is applied, the depletion layer due to the junction of the drift region 302 and the base region 308 is broadened. Hence no current flows between drain and source (the off state). Since the impurity concentration of the drift region 302 is lower than that of the base region 308, the depletion layer mainly expands on the side of the drift region 302. If the reverse bias voltage is made high and the electric field at the junction becomes equal to or greater than a certain electric field (Ecrit), avalanche breakdown causes a current to flow and results in a breakdown state. The drain-source voltage at Ecrit is BVDSS. FIG. 7 shows the junction between the drift region 302 and base region 308, which is the electric field relaxation layer, and the state at the time of electric field breakdown. If the impurity concentration in the drift region 302 is made low (if the resistivity is raised), the depletion layer during reverse bias is broadened further, and so BVDSS can be raised.
On the other hand, when a voltage is applied to the gate of the power MOSFET so as to turn on the MOSFET, the MOSFET enters the on state. At this time the path of on current flow is through the drift region 302, and so the on-resistance Ron depends on the resistance of the drift region 302. If the impurity concentration in the drift region is raised in order to lower the on-resistance Ron, BVDSS is lowered.
On the other hand, a Superjunction (SJ) structure is known as a structure in which there is no decline in BVDSS even if the resistance of the electric field relaxation layer is lowered. In this structure, by forming a region of conduction type opposite that of the drift region within the drift region, a depletion layer is formed in the drift region. In the technology disclosed in Japanese Unexamined Patent Application Publication No. 2001-298189, after epitaxial growth of Si on an Si substrate, a process of patterning and boron (B) ion implantation to form a p+ region, of conduction type opposite that of the drift region, is repeated a plurality of times.
On the other hand, in T. Henson and J. Cao, "Low Voltage Super Junction MOSFET Simulation and Experimentation", ISPSD-03 (2003), pp. 37-40, another example of a power MOSFET having a superjunction structure is described. In the technology described in Henson and Cao, a contact hole is formed extending from the substrate surface to the base region, with intermediate insulating film as a mask. In this case, the column region is formed by high-energy ion implantation after formation of the source electrode contact hole.
In a structure disclosed in Japanese Unexamined Patent Application Publication No. 2001-298189, it is necessary to repeat epitaxial growth, ion implantation and heat treatment; and the advantageous results of finer device patterns and substantial improvement in withstand voltage are diminished due to lateral broadening of the column region in consequence of mask alignment precision and thermal diffusion. There is the further disadvantage of increased costs due to the need to perform epitaxial growth a plurality of times. In the structure of Henson and Cao, the mask used in contact hole formation is also used as a mask during high-energy ion implantation, so that the contact hole must be made small. However, if in this structure the contact hole diameter is made smaller than approximately 1 μm, the metal which is to form the electrode (an aluminum alloy is principally used) cannot fill the contact hole interior, so that the on-resistance increases and other problems occur.
As described above, when forming a MOSFET as a conventional semiconductor device, there is the problem that it is difficult to employ finer device design rules while raising the breakdown voltage.

Semiconductor device and method for manufacturing same