A lubricant suitable for use in a trunk piston diesel engine characterised by a power output of 200 kW or greater. The trunk piston diesel engine may be for use in marine, power generation or rail traction applications. The lubricant comprises a basestock of lubricating viscosity, an overbased metal detergent, preferably having an ash content of at least 0.85% sulfated ash, and an ashless or metal-free auxiliary additive comprising at least one of: an oil-soluble sulfurized alkylphenol, a phosphorosulfurized or sulfurized hydrocarbon, a sulfide of an oil, a fat or a polyolefin, or an amine phosphate.

This invention relates to a lubricant suitable for use in a trunk piston diesel (compression-ignited) engine. Trunk piston diesel engines are used in marine, power generation and rail traction applications.
Trunk piston diesel engines are known for use in water-borne vessels, i.e. for so-called marine applications, including auxiliary power generation, and also for land-based applications such as power-generation. They may be characterised as medium-speed engines, e.g. in contrast to slow-speed cross-head engines requiring separate cylinder lubrication using a marine diesel cylinder lubricant.
Problems in the lubrication of trunk piston diesel engines may arise from the high temperatures to which the lubricant is subjected. For example, lubricating oil compositions, or lubricants, for trunk piston diesel engines (commonly referred to as trunk piston engine oils or TPEOs) may give non-optimal performance in their ability to resist formation of piston undercrown deposits.
The present invention provides a solution to the problem by using specific additives to enable the oil to resist the adverse effects of high temperature.
Thus, in a first aspect, the invention is a lubricant for use in a four-stroke trunk piston diesel engine, the lubricant comprising, or made by admixing:
(A) a base stock of lubricating viscosity, in a major amount;
(B) at least one overbased metal detergent, preferably having an ash content (as determined in accordance with ASTM D874) of at least 0.85% sulfated ash, in a minor amount; and
(C) at least one auxiliary ashless or metal-free additive component, in a minor amount, and that is different from (B), selected from:
(C1) an oil-soluble sulfurized alkylphenol, a phosphorosulfurized or sulfurized hydrocarbon, and a sulfide of an oil, a fat or a polyolefin, and/or
(C2) an amine phosphate.
A second aspect of the invention is a method of lubricating a four-stroke trunk piston diesel engine for use in marine, power generation or rail traction, the engine having a power output of 200 or greater, such as 400 or greater, preferably 550 or greater, more preferably in the. range of 600 to 100,000, kW, which method comprises supplying to the engine the lubricant defined above.
A third aspect of the invention is a method of raising the temperature of the onset of the hydrodynamic film in operation of a four-stroke trunk piston diesel engine for use in marine, power generation or rail traction, the engine having a power output of 200 or greater, such as 400 or greater, preferably 550 or greater, more preferably in the range of 600 to 100,000, kW, the method including the step of lubricating the engine with the lubricant defined above.
A fourth aspect of the invention is the use of additives (B) and (C) as defined above in a lubricant to suspend asphaltene components in the lubricant when used in a four-stroke trunk piston diesel engine in marine, power generation or rail traction, the engine having a power output of 200 or greater, such as 400 or greater, preferably 550 or greater, more preferably in the range of 600 to 100,000, kW.
The fourth aspect of the invention relates to a problem in use of TPEOs commonly referred to as xe2x80x9cblack paintxe2x80x9d whereby they may become contaminated with asphaltene components from the fuel used, when a residual fuel, leading to cleanliness problems in service. Thus, the lubricant in the present invention may further comprise a fuel oil with a residual fuel content, in a minor amount.
Phenate-based detergents may benefit the high temperature performance of TPEOs; however their use limits the amount of salicylate-based detergent, necessary for meeting the above-mentioned xe2x80x9cblack paintxe2x80x9d and other problems, that may be used. The present invention, by providing high temperature performance benefits other than arising from phenate use, enables more salicylate to be used as the detergent and thereby enables both high temperature performance and xe2x80x9cblack paintxe2x80x9d control requirements to be met. In the invention therefore, the lubricant may be substantially free of phenate-based detergents and/or comprise salicylate as the sole type of detergent.
In this specification, the following words and expressions shall have the meanings ascribed below:
xe2x80x9cmajor amountxe2x80x9dxe2x80x94in excess of 50 mass % of the lubricant;
xe2x80x9cminor amountxe2x80x9dxe2x80x94less that 50 mass % of the lubricant, both in respect of the stated additive and in respect of the total mass % of all the additives present in the lubricant, reckoned as active ingredient of the additive or additives;
xe2x80x9cactive ingredient (a.i.)xe2x80x9d refers to additive material that is not diluent.
xe2x80x9ccomprises or comprising, or cognate wordsxe2x80x9dxe2x80x94specifies the presence of stated features, steps, integers or components, but does not preclude the presence or addition of one or more other features, steps, integers, components, or groups thereof;
xe2x80x9cTBNxe2x80x9dxe2x80x94Total Base Numbers as measured by ASTM D2896;
xe2x80x9coil-soluble or oil-dispersiblexe2x80x9dxe2x80x94do not necessarily indicate solubility, dissolvability, miscibility or capability of suppression in oil in all proportions. They do mean, however, solubility or stable dispersibility sufficient to exert the intended effect in the environment in which the oil is employed. Moreover, additional incorporation of other additives may permit incorporation of higher levels of a particular additive, if desired; it will be understood that the various components of the lubricant, essential as well as optimal and customary, may react under the conditions of formulation, storage or use and that the invention also provides the product obtainable or obtained as a result of any such reaction.
The features of the invention will now be discussed in more detail as follows:
Trunk Piston Diesel Engine
The trunk piston diesel engine may, for example, be a four-stroke trunk piston diesel engine suitable for use in marine, power generation or rail traction applications. The engines preferably have a power output of 200 or greater, such as 400 or greater, preferably 550 or greater, more preferably in the range of 600 to 100,000, kW. Further, the engines may, for example, have an engine speed in the range of from 200 to 2,000, preferably 400 to 1,000, rpm, and a brake horse-power (BHP) per cylinder of 50 to 10,000, preferably 100 to 7,000.
Lubricant
The lubricant may, for example, have a TBN in the range of from 25 to 100, such as from 25 or 30 to 60, to 55, preferably, 40, for example in the range of from 60 to 100. Preferably, the viscosity index of the lubricant is at least 90, more preferably at least 95, and at most 140 such as 120, preferably 110. A preferred viscosity index range is from 95 to 115.
The lubricant may, for example, have a kinematic viscosity at 100xc2x0 C. (as measured by ASTM D445) of at least 9, preferably at least 13, more preferably in the range from 14 to 24, for example from 14 to 22, mm2sxe2x88x921.
(A) Base Stock of Lubricating Viscosity
The base stock is an oil of lubricating viscosity (sometimes referred to as base oil) and may be any oil suitable for the lubrication of a trunk piston engine. The lubricating oil may suitably be an animal, vegetable or a mineral oil. Suitably the lubricating oil is a petroleum derived lubricating oil, such as a naphthenic base, paraffinic base or mixed base oil. Alternatively, the lubricating oil may be a synthetic lubricating oil. Suitable synthetic lubricating oils include synthetic ester lubricating oils, which oils include diesters such as di-octyl adipate, di-octyl sebacate and tri-decyl adipate, or polymeric hydrocarbon lubricating oils, for example liquid polyisobutene and poly-alpha olefins. Commonly, a mineral oil is employed. The lubricating oil may generally comprise greater that 60, typically greater than 70%, by mass of the lubricant and typically have a kinematic viscosity at 100xc2x0 C. of from 2 to 40, for example from 3 to 15, mm2sxe2x88x921, and a viscosity index from 80 to 100, for example from 90 to 95.
Another class of lubricating oil is hydrocracked oils, where the refining process further breaks down the middle and heavy distillate fractions in the presence of hydrogen at high temperatures and moderate pressures. Hydrocracked oils typically have kinematic viscosity at 100xc2x0 C. of from 2 to 40, for example from 3 to 15, mm2sxe2x88x921 and a viscosity index typically in the range of from 100 to 110, for example from 105 to 108.
The term xe2x80x98brightstockxe2x80x99 as used herein refers to base oils which are solvent-extracted, de-asphalted products from vacuum residuum generally having a kinematic viscosity at 100xc2x0 C. from 28 to 36 mm2sxe2x88x921 and are typically used in a proportion of less that 30, preferably less than 20, more preferably less than 15, most preferably less than 10, such as less than 5, mass %, based on the mass of the lubricant.
(B) Overbased Metal Detergent
Overbased metal compounds suitable for use in the lubricant of the present invention include alkali metal and alkaline earth metal additives such as overbased oil-soluble or oil-dispersible calcium, magnesium, sodium or barium salts of a surfactant selected from phenol, sulfonic acid, carboxylic acid, salicylic acid and naphthenic acid, wherein the overbasing is provided by an oil-insoluble salt of the metal, e.g. carbonate, basic carbonate, acetate, formate, hydroxide or oxalate, which is stabilised by the oil-soluble salt of the surfactant. The metal of the oil-soluble surfactant salt may be the same or different from that of the metal of the oil-insoluble salt. Preferably the metal, whether the metal of the oil-soluble or oil-insoluble salt, is calcium.
Preferably, the TBN of the or each of the overbased metal compounds is at least 100, such as at least 250 and up to 500.
Surfactants for the surfactant system of the overbased metal compounds preferably contain at least one hydrocarbyl group, for example, as a substituent on an aromatic ring. The term xe2x80x9chydrocarbylxe2x80x9d as used herein means that the group concerned is primarily composed of hydrogen and carbon atoms and is bonded to the remainder of the molecule via a carbon atom but does not exclude the presence of other atoms or groups in a proportion insufficient to detract from the substantially hydrocarbon characteristics of the group. Advantageously, hydrocarbyl groups in surfactants for use in accordance with the invention are aliphatic groups, preferably alkyl or alkylene groups, especially alkyl groups, which may be linear or branched. The total number of carbon atoms in the surfactants should be at least sufficient to impart the desired oil-solubility.
Phenols, for use in this invention, may be non-sulfurized or, preferably, sulfurized. Further, the term xe2x80x9cphenolxe2x80x9d as used herein includes phenols containing more than one hydroxyl group (for example, alkyl catechols) or fused aromatic rings (for example, alkyl naphthols) and phenols which have been modified by chemical reaction, for example, alkylene-bridged phenols and Mannich base-condensed phenols; and saligenin-type phenols (produced by the reaction of a phenol and an aldehyde under basic conditions).
Preferred phenols may be derived from the formula
where R represents a hydrocarbyl group and y represents 1 to 4. Where y is greater than 1, the hydrocarbyl groups may be the same or different.
The phenols are frequently used in sulfurized form. Sulfurized hydrocarbyl phenols may typically be represented by the formula:
where x is generally from 1 to 4. In some cases, more than two phenol molecules may be linked by Sx bridges.
In the above formulae, hydrocarbyl groups represented by R are advantageously alkyl groups, which advantageously contain 5 to 100, preferably 5 to 40, especially 9 to 12, carbon atoms, the average number of carbon atoms in all of the R groups being at least 9 in order to ensure adequate solubility in oil. Preferred alkyl groups are nonyl (tripropylene) groups.
In the following discussion, hydrocarbyl-substituted phenols will for convenience be referred to as alkyl phenols.
A sulfurizing agent for use in preparing a sulfurized phenol or phenate may be any compound or element which introduces xe2x80x94(S)xxe2x80x94 bridging groups between the alkyl phenol monomer groups, wherein x is generally from 1 to about 4. Thus, the reaction may be conducted with elemental sulfur or a halide thereof, for example, sulfur dichloride or, more preferably, sulfur monochloride. If elemental sulfur is used, the sulfurization reaction may be effected by heating the alkyl phenol compound at from 50 to 250, preferably at least 100xc2x0 C. The use of elemental sulfur will typically yield a mixture of bridging groups xe2x80x94(S)xxe2x80x94 as described above. If a sulfur halide is used, the sulfurization reaction may be effected by treating the alkyl phenol at from xe2x88x9210 to 120, preferably at least 60xc2x0 C. The reaction may be conducted in the presence of a suitable diluent. The diluent advantageously comprises a substantially inert organic diluent, for example mineral oil or an alkane. In any event, the reaction is conducted for a period of time sufficient to effect substantial reaction. It is generally preferred to employ from 0.1 to 5 moles of the alkyl phenol material per equivalent of sulphurizing agent.
Where elemental sulfur is used as the sulfurizing agent, it may be desirable to use a basic catalyst, for example, sodium hydroxide or an organic amine, preferably a heterocyclic amine (e.g., morpholine).
Details of sulfurization processes are well known to those skilled in the art.
Regardless of the manner in which they are prepared, sulfurized alkyl phenols useful in preparing overbased metal compounds generally comprise diluent and unreacted alkyl phenols and generally contain from 2 to 20, preferably 4 to 14, and most preferably 6 to 12, mass % sulfur based on the mass of the sulfurized alkyl phenol.
As indicated above, the term xe2x80x9cphenolxe2x80x9d as used herein includes phenols that have been modified by chemical reaction with, for example, an aldehyde, and Mannich base-condensed phenols.
Aldehydes with which phenols may be modified include, for example, formaldehyde, propionaldehyde and butyraldehyde. The preferred aldehyde is formaldehyde. Aldehyde-modified phenols suitable for use are described in, for example, U.S. Pat. No. 5,259,967.
Mannich base-condensed phenols are prepared by the reaction of a phenol, an aldehyde and an amine. Examples of suitable Mannich base-condensed phenols are described in GB-A-2 121 432.
In general, the phenols may include substituents other than those mentioned above provided that such substituents do not detract significantly from the surfactant properties of the phenols. Examples of such substituents are methoxy groups and halogen atoms.
Salicylic acids used in accordance with the invention may be non-sulfurized or sulfurized, and may be chemically modified and/or contain additional substituents, for example, as discussed above for phenols. Processes similar to those described above may also be used for sulfurizing a hydrocarbyl-substituted salicylic acid, and are well known to those skilled in the art. Salicylic acids are typically prepared by the carboxylation, by the Kolbe-Schmitt process, of phenoxides, and in that case, will generally be obtained (normally in a diluent) in admixture with uncarboxylated phenol.
Preferred substituents in oil-soluble salicylic acids from which overbased detergents in accordance with the invention may be derived are the substituents represented by R in the above discussion of phenols. In alkyl-substituted salicylic acids, the alkyl groups advantageously contain 5 to 100, preferably 9 to 30, especially 14 to 20, carbon atoms.
Sulfonic acids used in accordance with the invention are typically obtained by sulfonation of hydrocarbyl-substituted, especially alkyl-substituted, aromatic hydrocarbons, for example, those obtained from the fractionation of petroleum by distillation and/or extraction, or by the alkylation of aromatic hydrocarbons. Examples include those obtained by alkylating benzene, toluene, xylene, naphthalene, biphenyl or their halogen derivatives, for example, chlorobenzene, chlorotoluene or chloronaphthalene. Alkylation of aromatic hydrocarbons may be carried out in the presence of a catalyst with alkylating agents having from 3 to more than 100 carbon atoms, such as, for example, haloparaffins, olefins that may be obtained by dehydrogenation of paraffins, and polyolefins, for example, polymers of ethylene, propylene, and/or butene. The alkylaryl sulphonic acids usually contain from 7 to 100 or more carbon atoms. They preferably contain from 16 to 80, or 12 to 40, carbon atoms per alkyl-substituted aromatic moiety, depending on the source from which they are obtained.
When neutralizing these alkylaryl sulfonic acids to provide sulfonates, hydrocarbon solvents and/or diluent oils may also be included in the reaction mixture, as well as promoters and viscosity control agents.
Another type of sulfonic acid that may be used in accordance with the invention comprises alkyl phenol sulfonic acids. Such sulfonic acids can be sulfurized. Whether sulfurized or non-sulfurized these sulfonic acids are believed to have surfactant properties comparable to those of sulfonic acids, rather than surfactant properties comparable to those of phenols.
Sulfonic acids suitable for use in accordance with the invention also include alkyl sulfonic acids, such as alkenyl sulfonic acids. In such compounds the alkyl group suitably contains 9 to 100, advantageously 12 to 80, especially 16 to 60, carbon atoms.
Carboxylic acids that may be used in accordance with the invention include mono- and dicarboxylic acids. Preferred monocarboxylic acids are those containing 1 to 30, especially 8 to 24, carbon atoms. (Where this specification indicates the number of carbon atoms in a carboxylic acid, the carbon atom(s) in the carboxylic group(s) is/are included in that number.) Examples of monocarboxylic acids are iso-octanoic acid, stearic acid, oleic acid, palmitic acid and behenic acid. Iso-octanoic acid may, if desired, be used in the form of the mixture of C8 acid isomers sold by Exxon Chemicals under the trade name xe2x80x9cCekanoicxe2x80x9d. Other suitable acids are those with tertiary substitution at the xcex1-carbon atom and dicarboxylic acids with more than 2 carbon atoms separating the carboxylic groups. Further, dicarboxylic acids with more than 35, for example, 36 to 100, carbon atoms are also suitable. Unsaturated carboxylic acids can be sulphurized. Although salicylic acids contain a carboxylic group, for the purposes of the present invention they are considered to be a separate group of surfactants, and are not considered to be carboxylic acid surfactants. (Nor, although they contain a hydroxyl group, are they considered to be phenol surfactants.)
Examples of other surfactants which may be used in accordance with the invention include the following compounds, and derivatives thereof: naphthenic acids, especially naphthenic acids containing one or more alkyl groups, dialkylphosphonic acids, dialkylthiophosphonic acids, and dialkyldithiophosphoric acids, high molecular weight (preferably ethoxylated) alcohols, dithiocarbamic acids, thiophosphines, and dispersants. Surfactants of these types are well known to those skilled in the art. Surfactants of the hydrocarbyl-substituted carboxylalkylene-linked phenol type, or dihydrocarbyl esters of alkylene dicarboxylic acids, the alkylene group being substituted with a hydroxy group and an additional carboxylic acid group, or alkylene-linked polyaromatic molecules, the aromatic moieties whereof comprise at least one hydrocarbyl-substituted phenol and at least one carboxy phenol, may also be suitable for use in the present invention; such surfactants are described in EP-A-708 171.
Further examples of detergents useful in the present invention are optionally sulfurized alkaline earth metal hydrocarbyl phenates that have been modified by carboxylic acids such as stearic acid, for examples as described in EP-A-271 262 (LZ-Adibis); and phenolates as described in EP-A-750 659 (Chevron).
Also suitable for use in the present invention are overbased metal compounds, preferably overbased calcium detergents, that contain at least two surfactant groups, such as phenol, sulfonic acid, carboxylic acid, salicylic acid and naphthenic acid, that may be obtained by manufacture of a hybrid material in which two or more different surfactant groups are incorporated during the overbasing process.
Examples of hybrid materials are an overbased calcium salt of surfactants phenol and sulfonic acid; an overbased calcium salt of surfactants phenol and carboxylic acid; an overbased calcium salt of surfactants phenol, sulfonic acid and salicylic acid; and an overbased calcium salt of surfactants phenol and salicylic acid.
By an xe2x80x9coverbased calcium salt of surfactantsxe2x80x9d is meant an overbased detergent in which the metal cations of the oil-insoluble metal salt are essentially calcium cations. Small amounts of other cations may be present in the oil-insoluble metal salt, but typically at least 80, more typically at least 90, for example at least 95, mole %, of the cations in the oil-insoluble metal salt, are calcium ions. Cations other than calcium may be derived, for example, from the use in the manufacture of the overbased detergent of a surfactant salt in which the cation is a metal other than calcium. Preferably, the metal salt of the surfactant is also calcium.
Preferably, the TBN of the overbased metal detergent is at least 330, such as at least 350, more preferably at least 400, most preferably in the range of from 400 to 600, such as up to 500.
In the instance where at least two overbased metal compounds are present, any suitable proportions by mass may be used, preferably the mass to mass proportion of any one overbased metal compound to any other metal overbased compound is in the range of from 5:95 to 95:5; such as from 90:10 to 10:90; more preferably from 20:80 to 80:20; especially from 70:30 to 30:70; advantageously from 60:40 to 40:60.
Particular examples of hybrid materials include, for example, those described in WO-A-97/46643; WO-A-97/46644; WO-A-97/46645; WO-A-97/46646; and WO-A-97/46647.
Typically, the amount of overbased metal compound in the lubricant is at least 0.5, particularly in the range of from 0.5 to 20, such as from 3 to 12 or 2 to 7, mass % based on active ingredient per mass of lubricant.
The overbased metal compounds of the present invention may be borated, and typically the boron contributing compound, e.g the metal borate, is considered to form part of the overbasing. In the instance where a borated overbased metal compound is used in the present invention, the use of a borated dispersant and/or an oil-soluble or oil-dispersible boron compound may, or may not, be necessary provided the lubricant composition comprising the borated overbased metal compound has a viscosity index and TBN as defined herein. For the purpose of avoidance of doubt, non-borated dispersants are not excluded in the present invention in combination with a borated overbased metal compound. The overbased metal compounds preferably have a sulfated ash content (as determined by ASTM D874) of at least 0.85%, more preferably at least 1.0% and even more preferably at least 1.2%.
(C) Auxiliary Additive Component
As stated, such components are xe2x80x9cashlessxe2x80x9d by which is meant that it is a non-metallic organic material that forms substantially no ash on combustion, in contrast to metal-containing and hence, ash forming compounds.
The auxiliary additive component (C1) may be selected from: oil-soluble sulfurized alkylphenols, phosphorosulfurized or sulfurized hydrocarbons, and sulfides of oils, fats or polyolefins, preferably in which a sulfur group having two or more sulfur atoms is adjoined and bounded together in a molecular structure. Examples include sulfurized sperm oil, sulfurized pinene oil, sulfurized soybean oil, sulfurized polyolefin, sulfurized esters, dialkyl disulfide, dialkyl polysulfide, dibenzyl disulfide, ditertiary butyl disulfide, polyolefin polysulfide, and thiadiazole type compounds such as bis-alkyl polysulfide thiadiazole. Such compounds fall within the component (C1) according to the present invention.
Component (C2) according to the present invention is an amine phosphate, which preferably includes the neutralisation or partial neutralisation products of acidic phosphorus-containing intermediates and amines. The acidic intermediates are preferably formed from a hydroxy-substituted triester of a phosphorothioic acid with an inorganic phosphorus reagent selected from the group consisting of phosphorus acids, phosphorus oxides, and phosphorus halides. Thus, the amine phosphates may, for example, be amine dithiophosphates.
The hydroxy-substituted triesters of phosphorothioic acids include principally those having the structural formula
in which R is selected from the class consisting of substantially hydrocarbon radicals and hydroxy-substituted substantially hydrocarbon radicals, at least one of the R radicals being a hydroxy-substituted substantially hydrocarbon radical, and X is selected from the class consisting of sulphur and oxygen, at least one of the X radicals being sulphur. The substantially hydrocarbon radicals include aromatic, aliphatic, and cycloaliphatic radicals such as aryl, alkyl, aralkyl, alkaryl, and cycloalkyl radicals. Such radicals may contain a polar substituent such as chloro, bromo, iodo, alkoxy, aryloxy, nitro, keto, or aldehydo group. In most instances there should be no more than one such polar group in a radical.
Specific examples of the substantially hydrocarbon radical are methyl, ethyl, isopropyl, secondary-butyl, isobutyl, n-pentyl, dodecyl, polyisobutene radical (molecular weight of 1500), cyclohexyl, cyclopentyl, 2-heptyl-cyclohexyl, phenyl, naphthyl, xenyl, p-heptylphenyl, 2,6-di-tertiary-butylphenyl, benzyl, phenylethyl, 3,5-dodecylphenyl, chlorophenyl, alpha-methoxy-beta-naphthyl, p-nitrophenyl, p-phenoxyphenyl, 2-bromomethyl, 3-chlorocyclohexyl, and polypropylene (molecular weight of 300)-substituted phenyl radical.
The hydroxy-substituted substantially hydrocarbon radicals include principally the above-illustrated substantially hydrocarbon radicals containing a hydroxy group. Those having less than 8 carbon atoms are preferred because of the convenience in preparing such hydroxy-substituted triesters. Examples of such radicals are hydroxymethyl, hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 2-hydroxycyclohexyl, 2-hydroxycyclopentyl, 2-hydroxy-1-octyl, 1-hydroxy-3-octyl, 1-hydroxy-2-octyl, 2-hydroxy-3-phenyl-cyclohexyl, 1-hydroxy-2-phenylethyl, 2-hydroxy-1-phenylethyl, 2-hydroxy-1-p-tolylethyl, and 2-hydroxy-3-butyl radicals. Other hydroxy-substituted substantially hydrocarbon radicals are exemplified by 2,5-dihydroxyphenyl, alpha-hydroxy-beta-naphthyl, 3-hydroxy-4-dodecyl, 3-hydroxy-6-octadecyl, and p-(p-hydroxyphenyl)-phenyl radicals.
A preferred class of the hydroxy-substituted triesters comprises those having the structural formula
in which Rxe2x80x3 is a substantially hydrocarbon radical illustrated above and Rxe2x80x2 is a bivalent substantially hydrocarbon radical such as alkylene or arylene radicals derived from the previously illustrated substantially hydrocarbon radicals. A convenient method for preparing such esters involves the reaction of a phosphorodithioic acid with an epoxide or a glycol. Such reaction is known in the art. The following equations are illustrative of the reaction.
in which
is an epoxide and HOxe2x80x94Rxe2x80x2xe2x80x94OH is a glycol.
For reasons of economy, aliphatic epoxides having less than about 8 carbon atoms and styrene oxides are preferred for use in the above process. Especially useful epoxides are exemplified by ethylene oxide, propylene oxide, styrene oxide, alpha-methylstyrene oxide, p-methylstyrene oxide, cyclohexene oxide, cyclopentene oxide, dodecene oxide, octadecene oxide, 2,3-butene oxide, 1,2-butene oxide, 1,2-octene oxide, 3,4-pentene oxide, and 4-phenyl-1,2-cyclohexene oxide. Glycols include both aliphatic and aromatic di-hydroxy compounds. The latter are exemplified by hydroquinone, catechol, resorcinol, and 1,2-dihydroxynaphthalene. Aliphatic glycols are especially useful such as ethylene glycol, trimethylene glycol, tetramethylene glycol, decamethylene glycol, di-ethylene glycol, triethylene glycol, and pentaethylene glycol.
Another convenient method for preparing the hydroxy-substituted triesters comprises the addition of a phosphorodithioic acid to an unsaturated alcohol such as allyl alcohol, cinnamyl alcohol, or oleyl alcohol such as is described in U.S. Pat. No. 2,528,723. Still another method involves the reaction of a metal phosphorothiate with a halogen-substituted alcohol described in U.S. Pat. No. RE. 20,411.
The phosphorodithioic acids from which the hydroxy-substituted triesters can be derived are likewise well-known. They are prepared by the reaction of phosphorus pentasulfide with an alcohol or a phenol. The reaction involves 4 moles of the alcohol or phenol per mole of phosphorus pentasulfide and may be carried out within the temperature range from about 50xc2x0 C. to 200xc2x0 C. Thus, the preparation of O,Oxe2x80x2-di-n-hexylphosphorodithioic acid involves the reaction of phosphorus pentasulfide with 4 moles of n-hexyl alcohol at 100xc2x0 C. for 2 hours. Hydrogen sulfide is liberated and the residue is the defined acid. The preparation of the phosphoromonothioic acid may be effected by treatment of corresponding phosphorodithioic acid with steam. Phosphorotrithioic acids and phosphorotetrathioic acids can be obtained by the reaction of phosphorus pentasulfide with mercaptans or mixtures of mercaptans and alcohols.
The reaction of phosphorus pentasulfide with a mixture of phenols or alcohols (e.g., isobutanol and n-hexanol in 2:1 weight ratio) results in phosphorodithioic acids in which the two organic radicals are different. Such acids likewise are useful herein.
The inorganic phosphorus reagent useful in the reaction with the hydroxy-substituted triesters of phosphorothioic acids is preferably phosphorus pentoxide. Other phosphorus oxides such as phosphorus trioxide and phosphorus tetroxide likewise are useful. Also useful are phosphorus acids, and phosphorus halides. They are exemplified by phosphoric acid, pyrophosphoric acid, metaphosphoric acid, hypophosphoric acid, phosphorous acid, pyrophosphorous acid, metaphosphorous acid, hypophosphorous acid, phosphorous trichloride, phosphorus tribromide, phosphorous pentachloride, monobromophosphorus tetrachloride, phosphorus oxychloride, and phosphorus triiodide.
The reaction of the hydroxy-substituted triesters of phosphorothioic acids with the inorganic phosphorus reagent results in an acidic product. The chemical constitution of the acidic product depends to a large measure on the nature of the inorganic phosphorus reagent used. In most instances the product is a complex mixture the precise composition of which is not known. It is known, however, that the reaction involves the hydroxy radical of the triester with the inorganic phosphorus reagent. In this respect the reaction may be likened to that of an alcohol or a phenol with the inorganic phosphorus reagent. Thus, the reaction of the hydroxy-substituted triester with phosphorus pentoxide is believed to result principally in acidic phosphates, i.e., mono- or di-esters of phosphoric acid in which the ester radical is the residue obtained by the removal of the hydroxy radical of the phosphorothioic triester reactant. The product may also contain phosphonic acids and phosphinic acids in which one or two direct carbon-to-phosphorus linkages are present.
The acidic product of the reaction between the hydroxy-substituted triester with phosphorus oxyhalide or phosphoric acid is believed to result in similar mixtures of acidic phosphates, phosphonic acids, and/or phosphinic acids. On the other hand, the reaction of the hydroxy-substituted triester with phosphorus trichloride or phosphorus acid is believed to result principally in acidic organic phosphites. Still other products may be obtained from the use of other inorganic phosphorus reagents illustrated previously. In any event, the product is acidic and as such is useful as the intermediate for the preparation of the neutralized products useful in invention.
Usually, from 2 moles to 5 moles of the triester is used for each mole of the inorganic phosphorus reagent. The preferred proportion of the triester is about 3-4 moles for each mole of the phosphorus reagent. The use of amounts of either reactant outside the limits indicated here results in excessive unused amounts of the reactant and is ordinarily not preferred.
The reaction of the hydroxy-substituted triester with the inorganic phosphorus reagent to produce the acidic intermediate can be effected simply by mixing the two reactants at a temperature above about room temperature, preferably above 50xc2x0 C. A higher temperature such as 100xc2x0 C. or 150xc2x0 C. may be used but ordinarily is unnecessary.
The amines useful for neutralizing the acidic intermediate may be aliphatic amines, aromatic amines, cycloaliphatic amines, heterocyclic amines, or carbocyclic amines. Amines having from 4 to 30 aliphatic carbon atoms are preferred and aliphatic primary amines containing at least 8 carbon atoms and having the formula, Rxe2x80x3xe2x80x94NH2, where Rxe2x80x3 is, for example, an aliphatic radical such as tert-octyl, tert-dodecyl, tert-tetradecyl, tert-octadecyl, cetyl, behenyl, stearyl, eicosyl, docosyl, tetracosyl, hexatriacontanyl, and pentahexacontanyl, are especially useful. Examples of other aliphatic amines include cyclohexyl amine, n-hexylamine, dodecylamine, di-dodecylamine, tridodecylamine, N-methyl-octylamine, butylamine, behenylamine, stearyl amine, oleyl amine, myristyl amine, and N-dodecyl trimethylene diamine, aniline, o-toluidine, benzidine, phenylene diamine, N,Nxe2x80x2-di-sec-butylphenylene diamine, beta-naphthylamine, alpha-naphthylamine, morpholine, piperazine, menthane diamine, cyclopentyl amine, ethylene diamine, hexamethylene tetramine, octamethylene diamine, and N,Nxe2x80x2-dibutyl-phenylene diamine. Also useful are hydroxy-substituted amines such as ethanolamine, diethanolamine, triethanolamine, isopropanolamine, para-aminophenol, 4-amino-naphthol-1, 8-amino-naphthol-1, beta-aminoalizarin, 2-amino-2-ethyl-1,3-propandiol, 4-amino-4xe2x80x2-hydroxy-diphenyl ether, 2-amino-resorcinol, etc.
Of the various available hydroxy-substituted amines that can be employed, a preference is expressed for hydroxy-substituted aliphatic amines, particularly those that conform for the most part to the formula
in which Rxe2x80x3 is as previously defined; A is a lower alkylene radical such as methylene, ethylene, propylene-1,2, tri-methylene, butylene-1,2, tetramethylene, amylene-1,3, pentamethylene, etc.; x is 1-10, inclusive; and Q is hydrogen, (AO)xH, or Rxe2x80x3. The use of such hydroxy-substituted aliphatic amines in many instances imparts improved rust-inhibiting characteristics. Examples of such preferred hydroxy-substituted aliphatic amines include N-4-hydroxybutyl-dodecyl amine, N-2-hydroxyethyl-n-octylamine, N-2-hydroxypropyl dinonylamine, N,N-di-(3-hydroxypropyl)-tert-dodecyl amine, N-hydroxytrieth-oxyethyl-tert-tetradecyl amine, N-2-hydroxyethyl-tert-dodecyl amine, N-hydroxyhexa-propoxypropyl-tert-octadecyl amine, N-5-hydroxypentyl di-n-decyl amine, etc. A convenient and economical method for the preparation of such hydroxy-substituted aliphatic amines involves the known reaction of an aliphatic primary or secondary amine with at least about an equimolecular amount of an epoxide, preferably in the presence of a suitable catalyst such as sodium methoxide, sodamide, sodium metal, etc.
In the above formulae, Rxe2x80x3, x and A are as previously defined. A particular preference is expressed for N-monohydroxyalkyl substituted mono-tertiary-alkyl amines of the formula tert-Rxe2x80x94NHAOH, wherein tert-R is a tertiary-alkyl radical containing from 11 to 24 carbon atoms. In lieu of a single compound of the formula tert-Rxe2x80x94NHAOH, it is often convenient and desirable to use a mixture of such compounds prepared, for example, by the reaction of an epoxide, such as ethylene oxide, propylene oxide, or butylene oxide, with a commercial mixture of tertiary-alkyl primary amines such as C11-C14 tertiary-alkyl primary amines, C13-C22 tertiary-alkyl primary amines, etc.
The neutralization of the acidic intermediate with the amine is in most instances exothermic and can be carried out simply by mixing the reactants at ordinary temperatures, preferably from 0xc2x0 C. to 200xc2x0 C. The chemical constitution of the neutralized product of the reaction depends to a large extent upon the temperature. Thus, at a relatively low temperature, such as less than 80xc2x0 C., the product comprises predominantly a salt of the amine with the acid. At a temperature above 100xc2x0 C., the product may contain amides, amidines, or mixtures thereof. However, the reaction of the acidic intermediate with a tertiary amine results only in a salt.
The relative proportions of the acidic intermediate and the amines used in the reaction are preferably such that a substantial portion of the acidic intermediate is neutralized. The lower limit as to the amount of amine used in the reaction is based primarily upon a consideration of the utility of the product formed. In most instances, enough amine should be used as to neutralize at least 50% of the acidity of the intermediate. For use as additives in hydrocarbon oils, substantially neutral products such as are obtained by neutralization of at least 90% of the acidity of the intermediate are desirable. Thus the amount of the amine used may vary within wide ranges depending upon the acidity desired in the product and also upon the acidity of the intermediate as determined by, for example, ASTM procedure designation D-664 or D-974.
A particularly preferred amine phosphate is when the acidic intermediate is derived from the reaction of P2O5 with hydroxypropyl O,O-di(4-methyl-2-pentyl) phosphorodithioate. This acidic intermediate may then be neutralised or partially neutralised with a C12 to C14 tertiary aliphatic primary amine. An example of such an amine may be commercially purchased under the trade name of Primene 81R.
The preferred component (C1) is an oil-soluble sulfurized alkylphenol. The preferred component (C2) is an amine dithiophosphate.
Component (C1) may, for example, be present in the lubricant is an amount of at least 0.1, preferably at least 0.3, 0.5, 1.5 or 2, and preferably up to 20, 15, 10, 8, 5 mass %; and component (C2) may, for example, be present in the lubricant in an amount of at least 0.1, for example up to 10, preferably in the range of 0.4 to 5, or more preferably 0.6 to 2, mass %.
Co-Additives
The lubricants may include an antiwear agent as a co-additive and may also contain other co-additives, for example, antioxidants, antifoaming agents and/or rust inhibitors. Further details of particular co-additives are as follows.
Oxidation inhibitors, or antioxidants, reduce the tendency of mineral oils to deteriorate in service, evidence of such deterioration being, for example, the production of varnish-like deposits on metal surfaces and of sludge, and viscosity increase. Suitable oxidation inhibitors include sulphurized alkyl phenols and alkali or alkaline earth metal salts thereof; diphenylamines; phenyl-naphthylamines; and phosphosulphurized or sulphurized hydrocarbons.
Other oxidation inhibitors or antioxidants that may be used in the lubricant comprise oil-soluble copper compounds. The copper may be blended therein as any suitable oil-soluble copper compound. By oil-soluble is meant that the compound is oil-soluble under normal blending conditions in the base stock or an additive package. The copper may, for example, be in the form of a copper dihydrocarbyl thio- or dithio-phosphate. Alternatively, the copper may be added as the copper salt of a synthetic or natural carboxylic acid, for example, a C8 to C18 fatty acid, an unsaturated acid, or a branched carboxylic acid. Also useful are oil-soluble copper dithiocarbamates, sulphonates, phenates, and acetylacetonates. Examples of particularly useful copper compounds are basic, neutral or acidic copper Cu I and/or Cu II salts derived from alkenyl succinic acids or anhydrides.
Additional detergents and metal rust inhibitors include the metal salts, which may be overbased and have a TBN less than 300, of sulphonic acids, alkyl phenols, sulphurized alkyl phenols, alkyl salicylic acids, thiophosphonic acids, naphthenic acids, and other oil-soluble mono- and dicarboxylic acids. Representative examples of detergents/rust inhibitors, and their methods of preparation, are given in EP-A-208 560. In the case of metal salts of salicylic acids, the TBN of the metal salts may be less than 200.
Antiwear agents, as their name implies, reduce wear of metal parts. Zinc dihydrocarbyl dithiophosphates (ZDDPs) are very widely used as antiwear agents. Especially preferred ZDDPs are those of the formula Zn[SP(S)(OR1)(OR2)]2 wherein R1 and R2 represent hydrocarbyl groups such as alkyl groups that contain from 1 to 18, preferably 2 to 12, carbon atoms.
Pour point depressants, otherwise known as lube oil flow improvers, lower the minimum temperature at which the fluid will flow or can be poured. Such additives are well known. Foam control may be provided by an antifoamant of the polysiloxane type, for example, silicone oil or polydimethyl siloxane.
Proportions
Typical proportions for additives for a TPEO (a trunk piston engine oil), additional to additives (C) of this invention, are as follows:
When a plurality of additives is employed it may be desirable, although not essential, to prepare one or more additive packages or concentrates comprising the additives, whereby several additives can be added simultaneously to the base stock to form the lubricant. Dissolution of the additive package(s) into the base stock may be facilitated by solvents and by mixing accompanied with mild heating, but this is not essential. The additive package(s) will typically be formulated to contain the additive(s) in proper amounts to provide the desired concentration, and/or to carry out the intended function, in the final lubricant when the additive package(s) is/are combined with a predetermined amount of base stock. Thus, components (B) and (C) in accordance with the present invention may be admixed with small amounts of base stock or other compatible solvents together with other desirable additives to form additive packages containing active ingredients in an amount, based on the additive package, of, for example, from 2.5 to 90 and preferably from 5 to 75 and most preferably from 8 to 60, mass %, with the remainder being base stock.
The final lubricant may typically contain about 5 to 40 mass % of the additive package(s), including diluent, with the remainder being base stock.


A woven filtration fabric for cellulosic sheet formation. The warp yarns comprise intrinsic binder yarn pairs, and a set of dedicated machine side layer warp yarns. The members of each intrinsic binder yarn pair alternate with each other to define a single combined path in each layer. Whenever a member interweaves with a machine side layer weft yarn, at least one machine side layer warp yarn interweaves with the same weft yarn in the same knuckle. In some embodiments, the members form double knuckles in the machine side layer, firstly together with a first machine side layer warp yarn and then together with a second machine side layer warp yarn. The warp yarn path ratio of machine side layer warp yarns to single combined paths of the intrinsic binder yarn pairs is at least 1.5:1. The fabrics provide increased center plane resistance, resulting in improved drainage and sheet uniformity.

This invention relates to flat woven industrial fabrics generally intended for filtration in sheet formation. However, the invention has particular applicability to papermakers' forming fabrics, and will be discussed primarily below in relation to such fabrics, although it is equally applicable to many industrial filtration uses where fiber support, fabric drainage rates and dimensional stability are important criteria.
In the discussion that follows, the following terms and corresponding abbreviations have the following meanings assigned to them:
Center Plane: a notional plane passing through the center of the fabric parallel to both the paper side (PS) and machine side (MS) of the fabric. In a woven fabric, this plane is occupied in part by the interwoven warp and weft yarns.
Center Plane Resistance (CPR): the resistance within the region of the center plane to the passage of fluid through the fabric. The amount of resistance is proportional to the extent to which the center plane is occupied by warp and weft yarns. The value of CPR for a fabric is calculated in terms of the amount of open area in a fabric, expressed as a percentage of the total area of the plane. Fabrics having relatively lower values of CPR (i.e. less open area available for drainage) will provide greater resistance to fluid flow than fabrics with relatively higher values of CPR (i.e. greater open area available for drainage).
Composite Fabric: a forming fabric comprised of at least two layers of warp and/or weft yarns in which at least one of the set of warp and/or weft yarns forming one surface (typically the paper side) of the fabric is also part of the opposite surface and serves to bind the two layers together to form the composite fabric (an example is Seabrook et al U.S. Pat. No. 5,826,627).
Cross-Machine Direction (CD): a direction perpendicular to the machine direction and in the plane of the fabric layer.
Drainage Area: the amount of open area on the paper side surface of the fabric which is available for fluid drainage and is not occupied by yarns, expressed as a percentage of the entire paper side surface area.
Fiber Support Index (FSI): a measure of the number of points provided by the paper side surface of a forming fabric available to support the papermaking fibers; FSI is calculated using the method described by Robert Beran in TAPPI J, Vol. 62, No. 4 (April 1979) p. 42, and discussed further below.
Float: refers to that portion of a component yarn which, in one repeat of the fabric weave, passes over or under a group of other yarns without interweaving with them; the associated term Float Length refers to the length of the float, expressed as the number of paper or machine side layer yarns over which the component yarn passes.
Frame Opening: the substantially rectangular open area between the interwoven warp and weft yarns on the paper side surface of a forming fabric. The related term Frame Length refers to the machine direction length of such an opening. Frame Count is the number of frame openings per unit area on the paper side surface.
Intrinsic Binder Yarn Pairs: two yarns that are woven according to the same apparent pattern in one fabric surface so that one replaces the other in sequence in the chosen weave path on that surface to effectively form a single combined path. Each pair member forms a part of the structure of one surface of a fabric and also passes beneath that surface to form a knuckle around at least one yarn in the layer of opposite surface to bind the two layers together. Intrinsic binder yarn pair members may be warp or weft yarns; in the present invention, they are warp yarns.
Knocking: the number of weft yarns per unit machine direction length in either the paper side or machine side of a fabric.
Knuckle: a locus in a woven fabric at which at least one yarn in a first direction passes around, and partially wraps about, a yarn in a transverse direction as a result of the weaving process.
Machine Direction (MD): a direction parallel to direction of movement of the web through the papermaking machine.
Machine Side (MS): the planar surface of a fabric opposite the paper side and in contact with the stationary elements of the papermaking machine.
Mesh: the number of warp yarns per unit CD width of fabric in either the PS or MS.
Paper Side (PS): the planar surface of a fabric on which the web is formed (also referred to as the sheet support surface).
Plain Weave: a weave pattern where each of the warp and well yarns pass in sequence, over one yarn and under one yarn.
Single Combined Path: the continuous path formed by the interweaving of intrinsic binder yarn pairs on a surface (typically the PS) of a fabric in a manner such that the yarns of the pair alternate with each other to appear in turn in the PS and MS layers, to complete together the chosen weave pattern.
Triple Layer Fabric: a forming fabric having two separate layers including weft yarns of three differing sizes—small yarns on the paper side layer, larger yarns on the machine side layer, and binder yarns, typically fine in size, interwoven between the layers to unite them.
Warp: yarns paid off a back beam in a loom and which, in flat woven fabrics, are oriented in the machine direction or length of the fabric.
Warp Yarn Path Ratio: the ratio of the number of single combined paths on the paper side of the fabric to the number of single warp yarns on the machine side of the fabric. In the fabrics of the present invention, there will be at least three warp yarns for every two single combined paths (1.5:1 ratio).
Weft: filling or "shute" yarns inserted across the width of a flat woven fabric and interwoven with the warp yarns.
In modern papermaking processes, as would be found for example in a twin wire gap or hybrid forming section, a highly aqueous stock comprising about 99% water and 1% papermaking solids is ejected from a headbox slice onto a moving forming fabric. The stock jet impinges the fabric over an impingement or forming shoe and is thereafter sandwiched by a second fabric and conveyed over various fabric support elements including blades and foils so as to agitate the stock and provide good sheet formation in the final paper product. This agitation is necessary in order to randomize the distribution and orientation of the papermaking fibers which, as has been established by measurement, on leaving the headbox and approaching the forming fabric prior to drainage are primarily aligned in the machine direction (MD). Agitation is also provided to avoid agglomeration of the fibers as flocs in the paper sheet.
Paper products evidencing uniform sheet formation are generally preferred for printing and like applications due to their more even ink absorption qualities and other properties such as the ratio of MD/CD (machine direction to cross-machine direction) tensile strength. Other desirable physical properties of the paper product are also enhanced when sheet formation is uniform. The nascent paper web is delivered from the forming section with a fiber to water percentage ratio of about 25/75 to the press section where further water removal occurs by mechanical means. The web is conveyed on a series of press fabrics through several press nips where a portion of the water is removed into the fabrics by pressure. As it exits the press section, the now somewhat consolidated sheet will consist of about 45% fiber and 55% water. It is then passed into the dryer section where the remaining water is removed by evaporative means as the sheet is exposed to heat sources, for example by being conveyed in a serpentine manner over numerous heated dryer cylinders while supported on a series of dryer fabrics. As it exits the dryer section to be wound onto reels, the sheet will consist of about 97-99% papermaking fibers and about 1-3% water.
The purpose of the forming fabric is to allow the water in the papermaking stock to drain through openings in the fabric while retaining the cellulosic fibers on the paper side (PS) surface to consolidate and become the embryonic sheet that will be passed into the downstream press section for further water removal. Virgin papermaking fibers intended for printing, newsprint and similar grades of paper generally have fiber lengths in the order of from about 1-3 mm depending on their source (i.e. softwood or hardwood). Increasingly greater amounts of fiber are now being derived from recycle sources where newsprint, cardboard and similar paper products are re-pulped and the fibers thus obtained are either mixed with a quantity of virgin fiber or supplied directly to the papermaking process. The re-pulping process tends to break the fibers and shorten them. With the increasing use of recycled stock, together with the use of fillers, it becomes proportionately more difficult to support and retain the shortened fibers on the PS of the fabric due to the size of the frame openings in the PS of the forming fabric. This problem is exacerbated by the fact that, as noted above, as the stock jet impinges the forming fabric, the papermaking fibers tend to be predominantly MD oriented. Depending on fabric design, the frame openings in the fabric may be square (e.g. in a plain weave over/under design) or they may be rectangular with the long side of the opening oriented in either the MD or the CD. It is well known in the industry that forming fabrics woven to provide either a plain weave PS surface, or one with rectangular openings oriented in the CD will provide better support for the fibers than fabrics with MD oriented rectangular openings.
Experiments by Robert Beran (TAPPI J., Vol. 62, no. 4 (April 1979), pp. 39-44) demonstrated that CD oriented fiber support as provided by the forming fabric yarns is more important for desirable papermaking than is MD support. Beran's Fiber Support Index (FSI) formula, which was developed as a result of his experiments, gives a weighting of 2:1 in favour of the CD yarn support over MD yarn support to optimize paper properties. This empirical relationship has been successfully applied by the paper industry for many years and is as follows:
      F                          S                          I    =                    (                  π          2                )                          (                  Z          λ                )              =                  (                  2          3                )                          (                              aN            m                    +                      2                                      bN              c                                      )            Where λ=mean fiber length                Nm=number of MD yarns/inch        Nc=number of CD yarns/inch        a,b=coefficients for contribution of support from MD and CD yarns, respectively (a function of weave pattern and running orientation)        Z=average number of supports per fiber.
In addition to providing a high degree of support for the papermaking fibers, drainage must occur in order to provide a somewhat consolidated fiber mat on the forming fabric surface which can then be transferred to the press section for further dewatering. With machine speed increases, this drainage through the forming fabric has to occur much faster than was previously the case. The area in the PS surface of the forming fabric which is available for drainage is referred to as drainage area. The drainage area is essentially a plan view of the open areas in between the mesh of the interwoven yarns through which fluid drains and is usually expressed as a percentage of the PS surface area.
The smaller the drainage area, the higher the differential pressure which is required to obtain the same volume of fluid in a given distance, i.e. if the differential pressure is not increased, a lower volume of fluid will be drained. This differential pressure is provided by drainage elements (e.g. foil blades, suction boxes, etc.) located beneath and in contact with the MS of the fabric. As the speed of the paper machine increases, it will be necessary to increase the differential pressure so as to maintain drainage; if this cannot be done effectively, then machine speed will have to be reduced to a point where adequate drainage of fluid from the sheet is obtained. Thus, fluid drainage through the forming fabric will impact and limit the speed at which paper can be made.
The drainage area of a fabric is calculated using the MD space between CD yarns and the CD space between the MD yarns. Beran's experiments showed that CD support is very important for paper properties as this is the span between the CD yarns which support the predominantly MD oriented fibers in the stock. Although the MD spacing between the CD yarns also plays an important role, the MD spacing between CD yarns is more important for papermaking properties.
The MD space between CD yarns is known as the frame length. With the decrease in papermaking fiber lengths in the stock due to the increased recycle content, it is advantageous for fiber support to reduce the frame length so far as possible, without adversely affecting other properties of the fabric. However, any reduction in the frame length will close up the drainage area unless the CD space between the MD yarns is correspondingly increased.
It is well known that a forming fabric woven at a relatively high mesh and knocking, using very small thermoplastic monofilament yarns in both the MD (warp) and CD (weft) can provide a very fine, smooth papermaking surface with the smallest holes possible. Monofilament yarn sizes in the range of about 0.10 mm to about 0.15 mm diameter are currently being used to weave the PS of some forming fabrics. These very small yarns enable the manufacturer to minimize the size of the frame openings in the fabric to the greatest extent possible. However, at papermaking speeds in excess of 1000 m/min, the stability of these finely woven textiles may become problematic. It is also difficult to provide a strong and reliable woven seam that will not fail under the high tensile loads imposed on the fabric. Still further, it is also very time consuming and expensive to produce fabrics with very small frame openings due to the required high knocking.
In conventional weaving of e.g. triple layer forming fabrics with a plain weave design on the PS, the MD and CD yarns are located in, and stay, in the same plane. Experience has shown that, during weaving, there are physical limitations as to how many CD (weft) yarns can be inserted into the plane before it becomes overcrowded. Over-crowding occurs when the total size of the warp and weft yarns is greater than the space that is available to accommodate them. In manufacturing terms, this is known as the crowd factor; a 100% crowd factor is reached when there is physically no more room for additional warp or weft yarns in a given space in the fabric. If additional yarns are forced into the fabric during weaving, either the yarns or the weave pattern will become distorted, which is undesirable.
Manufacturers of papermakers' forming fabrics strive to minimize the MD frame length in their products so as to maximize fiber support. For example, fabrics constructed in accordance with the claims of U.S. Pat. No. 5,826,627 (Seabrook et al.) are often woven to provide a knocking of about 100 weft yarns per inch (39.4 weft yarns per cm) of fabric length on the PS so as to achieve a very fine but open papermaking surface that will provide adequate fiber support and drainage area. However, this is inefficient as a weft yarn must be "shot" across the fabric width each time one is inserted into the woven structure; the higher the PS knocking, the slower fabric production will be. Further, at high weft yarn densities such as these, a minimum frame length limit is reached because there must be sufficient room between each successive weft to accommodate a warp yarn that is interwoven around each weft. The only way to reduce frame length in fabrics woven in this manner is to reduce the diameter of either, or both, the warp and weft. However, a practical lower limit on these yarn sizes will be reached, by reason of the need to maintain certain minimum limits of physical fabric properties.
It is therefore desirable to achieve a fabric design which will efficiently allow for a high degree of CD support for the papermaking fibers while providing for as small a frame opening as possible and maximizing the available drainage area; which can be woven efficiently; which provides for both a stable textile product capable of running at modern papermaking speeds; and which can be reliably seamed.
Forming fabric constructions which utilize the warp yarns as intrinsic binder yarns pairs are known. US 2006/0048840 (Quigley) discloses a composite forming fabric having a top and a bottom weave and includes interchanging binder warp yarns arranged in groups of at least two wherein for each group of binder yarns, the number of bottom warp yarns only weaving the bottom weave is higher than the number of top warp yarns only weaving the top weave. The disclosure includes only one FIG. (1A-1C) which must be considered the sole embodiment. This Figure shows a fabric in which there are no top warp yarns only weaving the top weave, but there are bottom warp yarns (W3) weaving only the bottom weave. Therefore, for each group of binder yarns (B1, B2), the number of bottom warp only weaving the bottom weave is greater than the number of top warp yarns only weaving the top weave. The application does not disclose any fabric in which there are any warp yarns dedicated to the top weave, and only discloses a fabric in which there is one dedicated bottom warp yarn (W3) for each group of binder yarns (B1, B2).
In particular, it has been found advantageous to provide weave patterns in which the warp yarns used in the PS weave pattern are provided by only intrinsic binder yarn pairs, which are interwoven with selected MS weft yarns, and warp yarns dedicated to the MS layer only, i.e. which do not pass into the PS, are interwoven with certain of the same selected MS weft yarns, in the manner discussed further below, to create a stable platform for the PS weave. Where the ratio of the number of MS warp to the number of effective PS warp which form single combined paths is at least 1.5:1, and where relatively short MD frame lengths are provided in the PS, this results in maximizing fiber support while providing a high open area so as to maintain drainage of the sheet. It has further been found that, due to the unique construction of these fabrics, their CPR is very high, in the range of about 16% to 30%, which serves to reduce straight-through drainage of fluid through the fabric thereby resulting in excellent sheet formation properties.
In the fabrics of the present invention, there are at least two warp yarns dedicated to the MS and interweaving the bottom weave (or MS weft) for every pair of binder warp yarns, and each binder yarn interlaces with the MS weft at a location where at least one MS warp also interlaces with the same MS weft to form a knuckle. Where there are two dedicated MS warp yarns for each pair of binder warp yarns, and the MS warp yarns follow separate paths from each other, each of the dedicated MS warp yarns combines with each member of an intrinsic binder yarn pair in turn to form the knuckles in each repeat of the weave pattern. Thus, for a fabric where the MS weave pattern comprises single knuckles, a first MS warp yarn interlaces a first MS weft yarn together with a first member of an intrinsic binder yarn pair to form a first knuckle, and then interlaces a second MS weft yarn together with the second member of the same intrinsic binder yarn pair to form a second knuckle. Similarly, the next adjacent dedicated MS warp yarn will interlace with the MS weft yarns to form a series of knuckles in which the two members of the intrinsic binder yarn pair alternate in interlacing with the respective MS weft yarns, in each case together with the dedicated MS warp yarn.
Where the MS weave pattern provides for an over 1, under 1, over 1 interweaving of the dedicated MS warp yarns with three successive MS weft yarns, to form a double warp knuckle, the members of each intrinsic binder yarn pair can be woven such that the first member is woven together with the corresponding dedicated MS warp yarn for the complete double warp knuckle, and the second member is woven together with that MS warp yarn for the next adjacent double warp knuckle. Alternatively, each member of the pair can be included in each double warp knuckle, by a first member being woven together with the corresponding MS warp yarn in the first part of the double warp knuckle and the second member being woven together with that yarn in the second part of the same double warp knuckle.
In the fabrics of this invention, all of the PS warp yarns are arranged as intrinsic binder yarn pairs such that when one warp of the pair is interweaving with PS weft yarns, the second member of the pair is either passing through the center plane of the fabric, or is weaving with selected MS weft yarns; i.e. each intrinsic binder yarn pair interweaves with the PS weft to form a single combined path in the PS. That path is comprised of relatively shorter woven PS segments made by each pair member as they interweave in turn with the PS weft yarns. Between each PS woven segment, each warp yarn forms long floats which pass through the center plane of the fabric before the yarn forms one or more knuckles with selected weft yarns of the MS layer each of which, as discussed above, is also interwoven with one, or both, of the MS warp so as to unite the PS and MS layers together. These long floats help to relieve the crowding conditions of a continuous plain weave, discussed above, while allowing a greater number of CD yarns to be woven into the structure than would be otherwise possible, without overcrowding the PS layer. In addition, the retained crimp created in the warp yarns of the intrinsic binder yarn pairs by the interweaving of these yarns to form the floats and knuckles in the fabric constructions of this invention will provide for a high strength woven seam which can be narrower than that provided in similar fabrics that do not employ these binder yarn pairs. Because the single combined path is comprised of 2 yarns, each of which is laterally displaced in the CD relative to the other, the CD distance between MD knuckles in the PS surface is doubled in comparison to that provided in a comparable fabric which does not include intrinsic binder yarn pairs. This lateral displacement, in combination with the long interior yarn floats, provides more PS drainage area than would otherwise be possible, while decreasing the frame length to maintain a high degree of fiber support.
In particular, it has been found that by creating the MS woven structure using warp yarns that are dedicated to the MS layer only and do not pass into the PS, a very fine woven structure can be provided on the PS, which structure alone would not be sufficiently rugged to withstand the forces to which such a fabric would be exposed in a modern high speed papermaking environment. The MS layer is comprised of MS weft interwoven with sets of 2 MS warp yarns which remain in the MS layer and cooperate together to form the weave pattern of the MS layer (i.e. one yarn replaces the other to complete the MS weave pattern). These MS warp yarns do not function as binder yarns to tie the MS and PS layers of the fabric together. Unlike the fabrics disclosed in EP 1630283 (Quigley) or U.S. Pat. No. 6,202,705 (Johnson et al.) or U.S. Pat. No. 6,581,645 (Johnson et al.), all of which disclose the use of single dedicated MS warp yarns in intrinsic binder yarn pair fabric constructions, the fabrics of the present invention employ sets of two MS warp yarns to increase the dimensional stability and provide a stable "platform" upon which the very fine PS layer is mounted, and at the same time increase the CPR, by reducing the open area available for drainage in the center plane. The ratio of the number of MS warp yarns in the fabric to the number of single combined paths in the PS is at least 1.5:1, taking the paths of the intrinsic binder yarn pairs to be effectively a single path. It has further been found to be particularly advantageous in the weave patterns of the invention for the dedicated MS warp yarns to interweave with the MS weft only at selected locations where one of the two warp yarns from the intrinsic binder yarn pairs interweave with the same selected MS weft, either in single or double warp knuckles, as discussed above.
This novel warp yarn arrangement allows for the formation of CD oriented rectangular openings in the PS of the fabric to increase papermaking fiber support, while the higher MS:PS warp ratio tends to close up the center plane and MS surface of the fabrics, thus retarding drainage and providing improvements in paper formation. The MS warp yarns are interwoven only with the MS well yarns to provide a rugged and stable platform to which the relatively fine PS surface is attached.
The invention therefore seeks to provide an industrial woven fabric for filtration in formation of a fibrous cellulosic sheet, the fabric having a sheet side layer with a sheet side surface and a machine side layer with a machine side surface, the fabric being woven to an overall repeating weave pattern and comprising
(i) sheet side layer well yarns;
(ii) machine side layer well yarns;
(iii) a first set of warp yarns comprising only intrinsic binder yarn pairs; and
(iv) a second set of warp yarns comprising machine side layer warp yarns, contributing only to the machine side layer and interwoven only with the machine side weft yarns,
wherein
(a) for each intrinsic binder yarn pair, the first and second members follow complementary identical paths in which the two members alternate with each other to appear in turn in the sheet side layer and the machine side layer and cooperate to define a single combined path in each of the sheet side layer and the machine side layer;(b) at each location at which a member of an intrinsic binder yarn pair interweaves with a machine side layer weft yarn to form a knuckle, at least one of the machine side layer warp yarns interweaves with the same machine side layer weft yarn in the same knuckle; and(c) a warp yarn path ratio of numbers of machine side layer warp yarns to single combined paths of the intrinsic binder yarn pairs is at least 1.5:1.
The invention further seeks to provide an industrial woven fabric for filtration in formation of a fibrous cellulosic sheet, the fabric having a sheet side layer with a sheet side surface and a machine side layer with a machine side surface, the fabric being woven to an overall repeating weave pattern and comprising
(i) sheet side layer weft yarns;
(ii) machine side layer weft yarns;
(iii) a first set of warp yarns comprising only intrinsic binder yarn pairs; and
(iv) a second set of warp yarns comprising machine side layer warp yarns, contributing only to the machine side layer and interwoven only with the machine side weft yarns,
wherein
(a) for each intrinsic binder yarn pair, the first and second members follow complementary identical paths in which the two members alternate with each other to appear in turn in the sheet side layer and the machine side layer and cooperate to define a single combined path in each of the sheet side layer and the machine side layer, such that in the machine side layer, each member of the pair interweaves in sequence with two of the machine side layer weft yarns together with a first member of a pair of adjacent ones of the machine side layer warp yarns at a first interweaving point, and together with a second member of the pair of adjacent ones of the machine side layer warp yarns at a second interweaving point; and(b) a warp yarn path ratio of numbers of machine side layer warp yarns to single combined paths of the intrinsic binder yarn pairs is at least 1.5:1.
Preferably, the fabric is a papermakers' fabric, the fibrous cellulosic sheet is a paper sheet, the sheet side layer is a paper side layer with a paper side surface, and the sheet side well yarns are paper side well yarns.
As discussed further below, preferably the fabric has a fiber support index calculated pursuant to Beran's Fiber Support Index of at least 100, more preferably of at least 140, and most preferably of at least 150.
Preferably, the sheet side surface has a drainage area of less than 45%, more preferably between 30% and 40%, and most preferably between 30% and 35%.
Preferably, the fabric has a frame count of between 3000/in2 and 6000/in2 (465/cm2 and 930/cm2). The number of frames provided per unit area will be dependent on the intended end use of the fabric and may be between 3300/in2 (511.5/cm2) and 4500/in2 (697.5/cm2). However, frame counts higher or lower than the preferred range are certainly possible.
Preferably, the sheet side surface comprises frames having a greater dimension in the CD than in the MD of the fabric. Preferably also, the frame length is less than 0.25 mm, more preferably less than 0.2 mm, more preferably less than 0.15 mm, and most preferably less than 0.1 mm.
Preferably, each MS warp yarn has a cross-sectional area which is substantially equal to, and more preferably greater than, a cross-sectional area of each warp yarn of an intrinsic binder yarn pair.
Preferably, the warp yarns of the first set (the intrinsic binder yarn pairs) each have a substantially circular cross-section and a diameter of between 0.08 mm and 0.25 mm, more preferably a diameter of 0.1 and 0.13 mm. Preferably, each MS weft yarn has a cross-sectional area which is substantially equal to, and more preferably greater than, a cross-sectional area of each PS weft yarn.
The yarns of each of the sets, i.e. the first set of warp yarns, the second set of warp yarns, the PS weft yarns and the MS weft yarns can suitably have a cross-sectional configuration selected from circular, ovate, elliptical, rectangular and square.
Preferably, the MS warp yarns each have a substantially circular cross-section and a diameter of between 0.08 mm and 0.3 mm; the PS weft yarns each have a substantially circular cross-section and a diameter of between 0.08 mm and 0.3 mm; and the MS weft yarns each have a substantially circular cross-section and a diameter of between 0.1 mm and 0.5 mm.
Preferably, the warp yarns employed in any of the first set and the second set are monofilaments formed from a polymer selected from: polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and a blend of PET and PEN; other polymers employed in the formation of monofilaments intended for use in industrial textiles such as papermaker's forming fabrics may also be suitable depending on the end use requirements of the textiles.
Preferably, the weft yarns are also monofilaments and are formed of a polymer including: a polyamide or co-polyamide, a polyester selected from polybutylene terephthalate (PBT), polytrimethylene terephthalate (PTT), PET, or a blend of PET and polyurethane such as is described in U.S. Pat. No. 5,169,711 or U.S. Pat. No. 5,502,120. When the chosen material is a polyamide, it is preferably selected from polyamide-6, polyamide-6/6, polyamide-6/10, polyamide 11, polyamide 12 and polyamide-6/12 or blends or copolymers thereof.
Preferably, the fabric has a drainage area in the center plane between the sheet side layer and the machine side layer of less than 40%, more preferably less than 30%, and most preferably less than 20%.
The fabrics of the invention can be woven using a loom equipped with either two or three warp beams, and according to an overall weave pattern requiring from 8, 12, 16 and 24 sheds in the loom (shed number). Two beams will be most suitable and are hence generally preferable. When the path lengths of one of the cooperating warp yarns in either the MS or PS differ, then a three beam loom will be required to accommodate the differing lengths.
Preferably, the single combined path of each pair of the intrinsic binder yarns comprises two segments separated by yarn exchange points, and the number of MS well yarns beneath each adjacent pair of yarn exchange points in one repeat of the overall fabric weave pattern is equal; alternatively, the number of MS weft yarns beneath each adjacent pair of yarn exchange points in one repeat of the overall fabric weave pattern is unequal. If this is done, then the fabric must be woven using a loom equipped with 3 warp beams so as to accommodate the various path lengths of the warp yarns.
In general, the weave designs chosen for each of the paper side layer and the machine side layer can be selected from various weave patterns known in the art. Preferably, the PS weave design is selected from the group consisting of a plain weave, a 2/1 twill, a 2/1 satin, a 3/1 twill, a 3/1 satin, and a design selected from known 2×2, 3×3, 3×6 and 4×8 patterns; preferably the weave design of the PS is a plain weave. The MS weave design can be selected from any of a group of well known designs including a plain weave, a twill and a satin weave; more preferably the design is selected from a 3×3, 4×4, 5×5, 6×6 and 6×12 design; most preferably it is selected from a 3×3 twill, a 6-shed broken twill, a 9×9 twill or an N×2N design in which N is the number of warp yarns and 2N is the number of well yarns in one repeat of the overall weave pattern.
The fabrics of the invention have a Fiber Support Index (FSI) value, calculated pursuant to Beran's Fiber Support Index, of at least 100 and preferably up to at least 150, most preferably between 150 and 175. The paper side drainage area is less than 45%, preferably 30% to 45%, most preferably 30% to 32%. The fabrics of the invention have a Center Plane Resistance in a notional central plane between the paper side layer and the machine side layer of less than 40%, preferably less than 30%, most preferably less than 20%.
Examples of the fabrics of the invention were woven, and compared with a control fabric woven according to U.S. Pat. No. 5,826,627 to Seabrook et al. (identified in Table 1 below as "Control"), and a similar fabric having an increased weft yarn count (Fabric 2 in Table 1). Fabrics 3 and 4 in Table 1 are two fabrics of the invention, as discussed further below.
Table 1:
In this Table, the various values for the features listed are stated in the units which are currently used in the industry as standard. However, applicable conversions are provided in relation to each of the features discussed in more detail in the text which follows the Table.
TABLE 1Fabric I.D.ControlFabric 2Fabric 3Fabric 4Fabric ConstructionU.S. Pat. No. 5,826,627U.S. Pat. No. 5,826,627InventionInventionPS WeavePlain WeavePlain WeavePlain WeavePlain WeaveYarn Count (1/in.)Paper Side MD × CMD74 × 9074 × 11037 × 9037 × 110Yarn Diameters (mm)PS/MD0.130.130.130.13PS/CD0.140.140.140.14Surface CharacteristicsDrainage Area31.3%24.5%40.9%31.9%Frame Count6660/in.28140/in.23330/in.24070/in.2Fibre Support Index (F.S.I.)169196145171Frame Length0.142 mm0.091 mm0.142 mm0.091 mmFrame OpeningsFrame Count/sq inch6660/in.28140/in.23330/in.24070/in.2Frame Length (mm)0.1420.0910.1420.091Frame Width (mm)0.2130.2130.5560.556Frame Area (mm2)0.0300.0190.0790.051
The PS weave of the Control fabric was a conventional plain weave; the yarn count in the PS surface was 74×90 (warp×weft) per inch (29.13×35.43 per cm). The PS warp yarn diameter was 0.13 mm and the PS weft yarn diameter was 0.14 mm. The PS drainage area was 31.3%, the frame count per square inch was 6660/in2 (1032.3/cm2) the FSI was 169 and the maximum MD frame length was 0.142 mm.
Fabric 2—In this sample the fabric was woven as a plain weave according to the same design and using the same yarn diameters as the Control fabric. However, in this case the CD well count was increased to 110/in. (43.3/cm) in order to give greater CD support to the MD oriented fibers. This had the desired effect of reducing the frame length to 0.091 mm and increasing the FSI up to 196, while increasing the frame count to 8140/in2 (1261.7/cm2). However, the drainage area of the PS was reduced from 31.3% to 24.5% (a 21.7% reduction). This considerable reduction in drainage area would reduce the volume of water drained through a fabric, if the same differential pressure was maintained.
Fabric 3—In this fabric of the invention, which is discussed further below in relation to the drawings, all the warps appearing in the PS were intrinsic binder yarn pairs, reducing by one-half the number of MD knuckles on the plain weave surface as the number of effective warp yarns is reduced from 74 to 37 by the use of the binder yarn pairs. The CD component of each frame opening was thereby increased to 0.556 mm from 0.213 mm, which increased the drainage area from 31.3% to 40.9% while using the same yarn diameters as in the Control fabric. The frame length of 0.142 mm was the same as in the Control fabric, but the frame count dropped down from 6660/in2 (1032.3/cm2) to 3330/in2 (516.15/cm2). The fewer MD yarns thus resulted in larger frames than in the Control fabric, but the FSI dropped from 169 to 145 because of the reduced MD support.
Fabric 4—In this second fabric of the invention, the more open structure of Fabric #3 was maintained, but the number of CD well yarns was increased to 110/in. (43.3/cm) as in Fabric #2 using the same diameter yarns as in that fabric. However, the use of intrinsic binder yarn pairs reduced the drainage area of Fabric #4 to 31.9% (similar to the Control fabric), but still much more open than Fabric #2 (at 24.5%). The maximum MD frame length was 0.091 mm (same as Fabric #2), but the FSI increased to 171 and the frame count rose to 4070/in2 (630.85/cm2) compared to 3330/in2 (516.15/cm2) for Fabric #3 and 6660/in2 (1032.3/cm2) for the Control fabric.
The data obtained from Fabric #4 clearly show that fabrics constructed using pairs of warp yarns arranged as intrinsic binder yarn pairs can provide a PS fabric surface having a high FSI value without sacrificing other important factors such as frame count and drainage area.

High fiber support intrinsic warp-tied composite forming fabric


The invention provides a fusion plate system, and method for installing this system upon a patient""s spine. The system uses a distractor device which measures an appropriately sized fusion plate for a corpectomy or discectomy application. Once a properly sized fusion plate is selected, the distractor device compresses the vertebrae and any associated bone graft placed between the vertebrae, thereby assuring maximum contact between the vertebrae and bone graft at a corpectomy or discectomy location. Compression is maintained by the distractor device while the fusion plate is anchored upon the corpectomy or discectomy site. Furthermore, the inventive fusion plate system and method results in the fusion plate being properly centered upon a patient""s spine, so that an aesthetically pleasing, as well as functional, surgical result is achieved.

This invention relates to appliances used in the stabilization and fusion of spinal vertebrae during and after spine surgery, and more specifically, relates to systems and methods for using a fusion plate for stabilizing vertebrae as part of a corpectomy or discectomy procedure to allow bone growth to occur.
Fusion plates have been in use as appliances for immobilizing and fusing adjacent spinal vertebrae following a discectomy (spinal disc removal) or for immobilizing the area surrounding a corpectomy (removal of an entire vertebral body). When these procedures are performed, a gap in the spine remains from the removed disc or vertebral body; this gap typically being closed by inserting a bone graft, usually from a cadaver. The adjacent vertebrae surrounding the discectomy or corpectomy site are then immobilized by attaching a fusion plate, usually on the anterior side of the spine, so that the vertebrae fuse to the bone graft, forming an entire fused section of the spine. Such fusing of vertebrae to the bone graft requires that the vertebrae remain immobile. Any movement during the healing process can cause a lack of fusion to occur, essentially forming a false joint in the spine at the discetomy or corpectomy site.
Presently, in performing a discectomy or corpectomy, a device called a xe2x80x9cdistractorxe2x80x9d is used to spread the adjacent vertebrae so that the disc or vertebral body of interest can be removed. In use, a pair of distractor pins, which are essentially screws having a head for engaging with the distractor, are screwed into the vertebrae adjacent to the discectomy or corpectomy site. One pin is placed in the upper vertebra, and a second pin is placed in the lower vertebra, both vertebrae being directly adjacent to the discectomy or corpectomy site. The distractor tool is then coupled to the pins on the upper and lower vertebrae, above and below the site, and the vertebrae are then mechanically spread apart, for aiding in the removal of any remaining portion of the deteriorated disc or vertebral body, and also to create a gap for placing a bone graft. Once the bone graft is placed, the distractor is removed; next, the distractor pins are removed from the spine, and finally, a fusion plate is placed in a position for keeping the adjacent upper and lower vertebrae as well as the bone graft immobilized. The plate is screwed into the upper and lower vertebrae the goal of which is to provide sufficient immobility to cause fusion between the vertebrae and bone graft to occur. Examples of fusion plates presently existing in the art, which are used in the heretofore described manner, are those produced by EBI Biomet, Inc., Dupuy AcroMed, Inc., and Spinal Concepts, Inc, to name a few.
Two drawbacks with the present fusion plate methods and systems are: 1) the plate is often positioned off-center on the spine, during these procedures, due to the fact that there has not been a system in place to properly align the fusion plate on the spine; and 2) the above methods rely only on the natural compression of the spine (e.g. once the distractor is removed), to compress the vertebrae sufficiently against the bone graft, to allow fusion to begin. With regard to the first drawback, a fusion plate positioned off-center can result in aesthetic objections from a patient in whom a fusion plate has been implanted. This often occurs when a patient examines his spinal X-ray following surgery and the fusion plate is off-center, or crooked, leading the patient to surmise that the surgeon has performed a haphazard job. With regard to the second drawback, the failure to sufficiently compress the vertebra and bone graft together, prior to placing and anchoring the fusion plate, results in unnecessary space remaining between these components, and reduces the likelihood that fusion will occur (this can cause the xe2x80x9cfalse jointingxe2x80x9d problems noted above).
Therefore, a need exists for a fusion plate system and method which allows a section of spine to be compressed adequately following a corpectomy or discectomy, so that sufficient immobilization and spinal fusion can occur. Additionally, a need exists for a fusion plate system and method which allows a fusion plate to be centered properly upon a spine.
The foregoing reflects the state of the art of which the inventor is aware, and is tendered with a view toward discharging the inventors"" acknowledged duty of candor, which may be pertinent to the patentability of the present invention. It is respectfully stipulated, however, that the foregoing discussion does not teach or render obvious, singly or when considered in combination, the inventor""s claimed invention.
The invention overcomes the drawbacks of the prior art by providing a modified fusion plate system, and method for installing this system upon a patient""s spine. This method and system allows a desired level of compression to be applied to the adjacent vertebrae surrounding the site of a corpectomy or discectomy, prior to, and during, the anchoring of the fusion plate. Furthermore, the inventive fusion plate system and method results in the fusion plate being properly centered upon a patient""s spine, so that an aesthetically pleasing, as well as functional, surgical result is achieved.
The inventive system and method relies upon mechanically compressing the spine to draw vertebrae together until these vertebrae are in contact with a bone graft located in the gap left by a corpectomy or discectomy. Once the spine is compressed, the fusion plate is guided to a centered positioning upon the spine over the site of the corpectomy. Finally, the fusion plate is anchored upon the spine, while the spine is still undergoing mechanical compression. The reliance of this system and method upon mechanical compression of the spine while the fusion plate is anchored, is intended to reduce spaces between the bone graft and adjacent vertebrae at the site of a corpectomy or discectomy, as much as possible, so that spinal fusion has the greatest chance of occurring.
In the preferred embodiment, the inventive system uses a distractor device to not only distract (e.g. spread) vertebrae, in the manner presently used, but additionally, to mechanically compress vertebrae and any bone graft located there between. Furthermore, the addition of sizing graduations to the inventive distractor device, correlating to the sizes of different fusion plates, allows a properly sized fusion plate to be selected by the surgeon for a particular application, with minimal trial and error.
The inventive system and method uses distractor pins to properly guide the fusion plate to a centered positioning upon a patient""s spine. Once guided onto the spine, the fusion plate is anchored with bone screws. The distractor pins are centered on the spine using anatomical landmarks such as the longis colli muscles or uncinate processes. The distractor pins are also designed for having a compressing force applied to them by the distractor device such that they do not bend or disengage from the distractor device upon compressing the spine to a desired level.
Accordingly, the following objects and advantages of the invention apply:
It is an object of this invention to provide a fusion plate system and method which results in improved fusion of spinal vertebrae following a corpectomy or discectomy.
It is another object of this invention to provide a fusion plate system and method which causes a fusion plate to be centered upon a patient""s spine.
Further objects and advantages of the invention will be brought out in the following portions of the specification, wherein the detailed description is for the purpose of fully disclosing preferred embodiments of the invention, without placing limitations thereon.

System and method for fusing spinal vertebrae

The Regents of the University of California


Device for dispensing multi-component compounds, in particular for dental purposes. It is equipped with a timer for indicating one or more times which are relevant to the working of the compound. This timer can be triggered by the start and/or the end of the running of the device.

Devices for mixing and dispensing multi-component compounds for dental purposes, for example as impression compound, are known. Since the reaction of the components begins with the mixing, there is only a limited working time available after the start of dispensing of the compound. An impression compound, for example, must be placed in the mouth before the working time has expired. The second important time for the dentist is the hardening time. In the case of an impression compound, this is the time it is necessary to wait before the material can be removed from the mouth. Although experience does give the dentist some feel for the length of time the compound can be worked and for when the material has completely set, mistakes regarding the time interval that has elapsed are still possible, especially in the case of complex impressions, and these mistakes can lead to incorrect results, for example poorly fitting impressions, and consequently to unnecessary expenditure in terms of time and cost. The same applies to other applications. For example, when preparing temporary crowns or bridges, it is necessary to observe the gelling time in which the mixed compound is in an elastic phase and can thus still be removed from the undercut tooth stump. The invention affords the user a means giving more precise information regarding the times available to him. According to the invention, a timer for indicating times which are to be observed is connected to the device for dispensing multi-component compound.
A particularly advantageous embodiment of the invention is one in which the timer is automatically triggered as a function of the running of the dispensing device. This preferably occurs at the start and/or at the end of the delivery procedure. If the working time is to be displayed, i.e. the length of time which at each point in time is still available for working the material, the timer runs from the start of the delivery procedure. If the hardening time is to be displayed, i.e. the length of time after which the last-applied material has also hardened, the timer runs from the end of the delivery procedure. Since the delivery time can vary greatly between different working techniques, the two time intervals can be differently staggered in relation to each other. For example, the movement of a switch, with which the dispensing device is started up, can simultaneously start the timer for the working time. Correspondingly, using the switch with which the dispensing is ended, a second timer can be started up which displays the hardening time.
As regards the way in which the timer signals the time, recourse may be had to known display possibilities. For example, the time still remaining at each point in time until expiry of the working time or hardening time can be displayed in seconds or minutes. Alternatively, the length of time which has elapsed since the timer was started is displayed. Since the dentist should have the possibility of controlling the preset time interval in each case and of adjusting his work thereto, this time interval should be displayed before the delivery procedure has commenced. In many cases, one signal is sufficient for displaying the end of the set time, for example the working time or the hardening time. If the time concerned is one where it is necessary to do something before the said time has expired (working time, gelling time), the signal is given before the time has expired, so that the dentist still has time to act, or a preliminary signal is given before the signal which indicates the time has expired. If, by contrast, the expiry itself is relevant, only this need be signalled. The signal can be an acoustic one, for example, so that the dentist can give his full visual attention to the patient. The timer is preferably reset automatically to the initial status, i.e. to the preset time interval, after the display. In another variant, the timer is reset automatically to the initial status on each newly commencing delivery procedure.
If only compounds are ever to be worked having about the same duration of the relevant time interval or time intervals, the respective display interval of the timer can be preset by the manufacturer such that it cannot be altered. Instead of this, it is also possible for the time interval of the timer to be set by the user for each case of use. A further possibility is one in which although the time interval can be adjusted, the selected setting is stored so that it does not have to be selected again upon each use.
If compounds with different working, gelling and hardening times can be worked in one dispensing device, which compounds are fitted in the device in the form of exchangeable cartridges, it is particularly advantageous for the exchangeable cartridges and the device or the timer to be provided with interacting facilities for automatically setting the time interval to be given to the timer. To do this, it is possible, for example, to use the technique which is known for automatically setting the film sensitivity in cameras. The device is equipped with a facility for reading a bar code, punched code, color code or magnetic strip code provided on the cartridge. The code can be applied directly on the cartridge and can also be read directly from there. However, it is also possible to provide the code separately from the cartridge or container holding the material and to read the code at another point on the device. For example, it can be arranged on a packaging or on a control chip which is enclosed with the package and which delivers the desired control commands for the timer. With the code or with the chip, in whichever form it may be provided, other material-dependent functions of the device can also be controlled, for example the mixing speed, the delivery speed or the dispensing quantity. The latter, for example, can be predetermined by the timer as a function of the dispensing time. The automatic presetting of the display of the working time or hardening time should be able to be manually overridden in order to allow the user to adapt to different working conditions.

Device for dispensing multi-component compounds for dental purposes