US 3459506 A
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Aug. 5, 1969 T. w. FINUCANE METHOD AND APPARATUS FOR DETERMINING AMOUNT OF LUBRICANT PRESENT ON TEXTILE FIBERS Filed Aug. 1, 1966 E IIIII TH OMAS w. F/NUCANE INVENTOR.
ATTORNE 5 United States Patent Thomas W. Finucane, Kingsport, Tenn, assignor to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey Filed Aug. 1, 1966, Ser. No. 574,886 Int. Cl. Gllln 31/16, 33/36, 1/28 US. Cl. 23230 7 Claims This invention relates to a method and apparatus by which the amount of lubricant present on textile fibers may be determined. More particularly, this invention relates to a method and apparatus by which the percent lubricant on textile fibers may be rapidly and accurately determined through utilization of the technique of titration.
In the textile industry it is oftentimes necessary, for production quality control and/ or experimental purposes, to determine the percent by weight of lubricant oil that is present on a textile fiber or filament. This determination is necessary since a light coat of oil or other lubricant is generally applied to the staple fibers or yarn product of it has been formed to permit it to smoothly flow through subsequent processing equipment such as, for example, carding or winding equipment. For any particular lubricant oil applied to the fibers or yarn product there is an optimum percent oil range, and processing troubles inevitably occur whenever the oil level reaches a value very far outside this range. For example, too much oil on the fibers would cause gumming of downstream equipment, and too little oil would increase the coefiicient of friction between the fibers and the processing equipment and the tendency of the fibers to generate static electricity to the point where the efficiency of, for example, the carding operation would be seriously impaired. In some cases in the synthetic fiber industry the optimum lubricant oil level may be as low as one-tenth of a percent by weight of the fiber or lower, and such low lubricant oil levels have been most difiicult to measure with desired accuracy and rapidity by known methods.
In the past, percent lubricating oil on a synthetic fiber has been determined by techniques such as ether extraction by use of Soxhlet extraction equipment. In these techniques the oil on a given length of fiber is generally extracted by dissolving it in ether. After extraction, the ether is evaporated and the residue weighed to determine the percent oil present on the fiber. This, of course, is a long and laborious laboratory procedure, and has hindered the experimental or developmental improvement of fiber lubricating oils because of delays encountered in obtaining tests results. Production quality. control of synthetic fibers has also been hindered because tests must be carried out in the laboratory thereby creating lag time between receipt of samples by the laboratory and receipt of data by the production line. The lag time becomes particularly critical where the operation of the production line is dependent on the test results. The Soxhlet extraction method has been used in the past primarily because of its accuracy in measuring oil levels above 1 percent and because no suitable and practical replacement had been found.
The method of this invention is based upon the concept that it is possible to determine quantitatively, by titration, the amount of a lubricant oil present on a fiber without completely isolating the oil by extraction. The lubricant must, of course, carry a titratable material. Components in the oil other than the titratable material must be either inert with respect to the test or have a predictable response while the percent of titratable material in a sample varies. Thus, the method of this invention basically involves the steps of providing a lubricant ice oil that has a titratable material therein, selecting a known weight of the fibers coated with the lubricant oil, placing the lubricated fibers in a liquid medium, vigorously agitating the liquid medium, and adding a titrant until the end point of the titration is reached.
Titration is a test method in which a liquid medium containing a known concentration of a first material (the titrant) is added to another liquid medium containing an unknown concentration of a second material (the analyte) that will react with the titrant. The titrant is added until there is some indication that an amount of the titrant equivalent to the analyte of unknown concentration has been added, that is, until the endpoint of the titration is reached. It is then possible to calculate the amount of analyte presented by a test sample when the stoichiometry is known for the manner in which the titrant reacts with or is equivalent to the analyte of unknown concentration, or when a factor has been obtained as, for example, by titrating samples whose percent oil is known.
However, with the titration technique there generally arises the problem of rapidly placing the analyte into solution so that accurate titration of the analyte solution with the titrant may begin. In addition, once titration begins, there remains the problem of instant mixing of each titrant addition with the analyte solution so that the titration may be carried out as quickly as possible. There are, of course, known means for effecting mixing of the analyte solution with the titrant, for example, magnetically driven stirrer bars, electrically driven paddle stirrers, and vibrating or shaking apparatus. However, in each of these cases the titration is generally carried out by hand in open vessels, thus causing loss in efficiency as well as rapidity and accuracy in attempting to secure quality control or experimental data.
The titration apparatus of this invention alleviates the above mentioned problems inherent with the technique of titration by providing a closed fluid circulation system through which a liquid medium is continually circulated. Thus, complete rapid and efiicient mixing of the titrant with the liquid medium is ensured as the titrant is added thereto. In addition, because of the continuous solvent circulation the analyte is constantly subjected to the titrant carried by the liquid medium, thereby providing instantaneous acceptance by the analyte ions of the titrant ions. The titration apparatus of this invention also includes means whereby all atmospheric air is excluded from the system, the system operating under an inert gas atmosphere, thereby tending to minimize test result discrepancies due to varying blank values and errors introduced through air and water variables in the system.
In general, the titration apparatus of this invention in-- cludes a fiber sample holder, an end point determinator and a fluid circulating pump connected together to constitute the fluid circulation system, and means for regularly supplying a titrant to the circulation system. By isolating the fiber samples from the agitating means, that is, the circulation pump, the liquid medium, the titrant and the sample are brought into intimate contact without requiring contact of the agitator and the sample itself.
A liquid medium supply source may be integrated with the fluid circulation system to supply fresh liquid medium to the system when it is sought to introduce a new test sample. An inert gas supply source may also be provided to purge the system of atmospheric air as well as to provide the pressure necessary to recharge the system with a fresh charge of the liquid medium.
Accordingly, it has been an object of this invention to provide an improved method of determining percent lubricant on a fiber that is etficient and practical.
It has been another objective of this invention to pro vide an improved method of determining percent lubricant on a fiber that utilizes the technique of titration.
It has been still another objective of this invention to provide titrating apparatus for carrying out the method of this invention which is rapid and accurate.
It has been another objective of this invention to provide titration apparatus that quickly exposes the titrant ions to the analyte ions, as soon as the titrant is added to the liquid medium that envelops the fiber sample, by continuously circulating the liquid medium past the fiber sample.
These and other objects and advantages of the present invention will be more readily apparent from the following detailed description taken in conjunction with the accompanying drawing which is a diagrammatic illustration of the preferred embodiment of the invention.
By the method of this invention, a lubricant oil must be provided for the fiber which contains a titratable analyte. After selecting a fiber sample having lubricating oil thereon, the sample is Weighed. The sample of known weight is then immersed in a liquid medium that is vigorously agitated. The analyte present in the lubricant oil is subsequently titrated by means of a suitable titrant until the titration endpoint is reached. Any type of chemical reaction which causes a titratable endpoint may be employed such as, for example, acid-base or neutralization reactions, oxidation-reduction reactions, or precipitation or complex ion formation reactions may be used. Thus, when the percent analyte in the lubricant oil is known, from known stoichiometric relationships, it is possible to determine the quantitative amount of lubricant present on the fiber sample without isolating or extracting the oil from the fiber and weighing it separately.'Of course, the other components in the mixture must either be inert with respect to the test or have a predictable response, that is, remain constant while the percent oil varies. The nonreacting other components constitute a blank value which is compensated for in the test result data so that percent oil may be calculated. To achieve low, as well as reproducible, blank values the liquid medium should be substantially inert in the titration; for example, in some applications carbon dioxide and water should be excluded from the titration system.
There must, of course, be an analyte present in the lubricant oil which is titratable. In the case of lubricant oils developed for use on synthetic fibers, generally all such oils contain anti-static agents in known proportions. The anti-static agents often contain cations that are amines and are, therefore, easily titratable. If, however, the lubricant oil has no titratable material present therein initially, such a material may be added thereto for purposes of deter-mining the percent oil by titration.
The liquid medium in which the lubricated fiber sample is immersed is essentially a carrier medium for the purpose of effecting contact between the titrant ions and the analyte ions present in the lubricant oil. The liquid medium may or may not have a solvent effect on the analyte as titration of the analyte may take place whether the analyte in the fiber lubricant oil is in solution, in suspension, or still attached to the fiber sample. The very important criteria is that the liquid medium must be vigorously agitated so that titrant added to the liquid medium may be quickly and effectively contacted with the analyte ions. Of course, the mere fact that a solution of the analyte ions is not required greatly increases the speed with which the titration may be performed without adversely affecting the precision of the results.
In the titration of the oil lubricated fiber samples, it is preferred to use a nonaqueous liquid medium such as, for example, anhydrous isopropanol. Commercial type fiber lubricant oils are generally neutral in character; however, upon being subjected to a nonaqueous media, the amine cations in the anti-static agents usually present therein are dehydrated and, thus, make the lubricants acidic and available for titration. It is preferred to use KOH as the titrant in conjunction with anhydrous isopropanol and oil lubricated fiber samples.
In accordance with the principles of the invention, the drawing depicts one preferred form of the titration apparatus. The titration apparatus includes a closed circulation system comprising a centrifugal pump 10, a sample holder 11, and an end point determinator or sight glass 12. Also, included in the preferred embodiment are a titrant supply tank 13, a solvent supply tank 14, and an inert gas supply tank 15. The pump 10, sample holder 11, and sight glass 12 are connected together in a closed, fiuid circulation system by means of suitable piping 16, 17, 18, thus forming the liquid medium flow path during the titration of a test sample. Titrant 19 is maintained in the titrant tank 13, which tank communicates with the pump 10 through piping 20 and solenoid 21. The titrant tank 13 includes titrant metering means or burette 22 that is equipped with a stopcock 23 to meter the titrant 19 into the fiuid circulation system.
The titrant 19 is preferably maintained under gas pressure from a supply of inert gas, for example, nitrogen, in the tank 15. A gas supply line 24 is provided between the gas tank 15 and the titrant tank 13 so that reverse flow into the tank 13 from the fluid circulation system will be prevented. The line 24 includes a pressure reducer valve 25 with indicator gauges 26, 27, a bleed-type pressure regulator valve 28 with indicator gauge 29, and a solenoid 30. A first branch gas supply line 31 is provided between line 24 and the sight glass 12, the line 31 carrying a solenoid 32 and a check valve 34. A second branch gas supply line 36 intercepts the line 24 between the solenoid 3t) and the gauge 29, and extends to the tank 14. Located in the line 36 are a solenoid 37 and a check valve 38.
Line 39 is connected at one end to the pump 10 and at the other end communicates with the inside of the tank 14. Located within the line 39 are three solenoids 41, 42, and 43. An exhaust line 44 is connected to line 39 between solenoid 41 and solenoid 42, the line 44 carrying solenoid 45 whereby the titrated solution may be flushed or exhausted from the system after the end point of a sample titration has been reached.
Located intermediate the check valve 38 and solenoid valve 43 in the lines 36, 39 is the liquid medium supply tank 14. A solution 46 of a liquid medium and an endpoint indicator (when color charge endpoint determination are used) is kept in the tank 14. Inert gas may be passed into the tank 14, through line 47, and exit through piping and cock 48. Thus, the indicator and solvent may be thoroughly mixed when a new solution 46 thereof is placed in the tank 14 by permitting the inert gas from the tank 15 to bubble through the solution 46 and out the piping and cock 48.
In operation, the liquid medium-indicator solution 46 is prepared and placed in the tank 14. A sample of fibers having an unknown percent by weight of lubricating oil thereon is placed in sample holder 11 by removing lid 50 and placing the sample inside the holder. Restraining means, such as a foraminous basket, inside the holder 11 maintains the sample inside the holder and does not permit it to circulate within the circulation system. If the solution 46 is newly prepared and has just been placed in the tank 14, the solenoid 37 and the cock in line 48 are opened and an inert gas such as nitrogen is forced past check valve 38 into the solution 46 through line 47. The nitrogen bubbles through the solution 46 and out the line 48, thus causing intimiate agitation and mixing of the liquid medium-indicator solution. This step permits reduction in experimental errors that may arise through inadequate mixing of the solution 46 and also reduces the carbon dioxide and atmospheric air present in the tank 14, which also causes experimental error if present in unknown quantities in the circulating system. Thus, not only are blank values or constants which are necessary to make percent analyte calculations reduced, but these values are made more uniform, thereby permitting more exact reproducibility of results. After mixing and purging, the line 48 on the tank 14 is closed and the inert gas pressure permitted to build up in the tank to, for example, 3 or 4 p.s.1.
Once the sample is in the sample holder 11 and the lid 50 is tightened, the solenoids 30, 41 and 45 may be opened to permit the inert gas to flush the fluid circulating system of atmospheric air, with the exhaust passing out through the solenoid valve 45. Solenoid 30 is then closed to permit charging of the solution 46 into the closed circulating system.
To ready the titration apparatus for titration of an analyte carried by the lubricant oil on the fiber sample that has been placed in the sample holder 11, solenoids 32, 41, 42 and 43 are opened. The inert gas in the tank 14 then forces a charge of solution '46 from the tank 14 into the fluid circulation system, that is, into the pump 10, the sample holder 11, and the sight glass 12. The level of the solution 46 is permitted to rise in the sight glass 12 until a predetermined index point is reached. When the index point has been reached, solenoid valves 21 and 30 are opened, the motorized centrifugal pump is actuated, and all other valves are closed. Thus, the fluid circulation system is closed and the flow path of the solution 46 .passes from solenoid 21 into the motor 10, through the sample holder 11, through the sight glass 12, and back through the solenoid valve 21. It will be appreciated that this type system permits the liquid flow through the cycle to be continuous and rapid thereby helping the titrant to rapidly contact the analyte present in the lubricant oil. Measured amounts of the titrant 19 are added from the titrant tank 13 by means of the burette 22 and the cock 23 until the endpoint of the titration is reached. When an indicator fluid is present in the solvent, as in this preferred embodiment, the endpoint is determined by visually observing a simple change in color of the titrated solution by watching sight glass 12.
During the titration, the burette 22 is opened to gas pressure through the solenoid valve 30, and the sight glass 12 is also opened to gas pressure through the solenoid valve 30 and check valve 34. By maintaining the system under an inert gas pressure, the entrance of air during the cycling of the titrant 19 and solution 46 is minimized. Also the pressure in the burette 21 is maintained at a high enough level to prevent reverse flow, that is, to prevent the circulating solution from backing up into the tank 13. Because all the solenoids in the apparatus, except those mentioned, are closed during titration, only inert gas can enter the burette 22 and no further protection from water or carbon dioxide is needed.
Once the analyte that was present in the sample has been titrated and an endpoint has been reached, solenoids 41 and 45 are opened while solenoid 30 remains open. This permits the titrated or now useless solution to be drained from the system, thereby leaving the sight glass 12 empty. The solenoid 21 is subsequently closed and the remaining liquid in the sample holder 11 also driven from the fluid circulation system through solenoid 41 and 45.
The lid 50 is then removed from the sample holder 11, the old sample removed, and a new sample inserted therein with the operation commencing as before described.
The solenoids utilized in this apparatus may be connected through electrical circuitry, not shown or constituting a part of this invention, to a suitable central control panel so that the operation of the solenoids required to carry out any specific step may be simultaneous.
The endpoint determinator of this invention has been shown, in the preferred embodiment, to be a sight glass 12 wherein the change of an indicator color may be visually observed. However, other embodiments of this invention may include other types of endpont indicating means such as: optical methods, for example, photometric endpoint determination; or electrical methods, for example, conductimetric, potentiometric or amperometric endpoint determination.
The above described apparatus may be provided in a very compact, portable form so that it may be carried or positioned at any desired point in a synthetic fiber plant, thereby eliminating the delays in the transmission of data from the quality control laboratory to the production line and samples from the production line to the laboratory.
In determining the amount or level of lubricating oil carried by fibers as they are being processed in the textile industry, the usefulness of the titration method and apparatus of this invention is immeasurable in giving quick and accurate data for percent oil on the fibers, particularly where a low level of lubrication is present (see the example below). Also the titration method and apparatus of this invention, when used in the determination of percent oil lubricant on fibers, avoids the severe fire and explosion hazards associated with the ether extraction method.
In order that the accuracy of the titration method and apparatus embodied in this invention may be shown in relation to the Soxhlet ether extraction method, as its use relates to the synthetic fiber industry, comparison tests were run with the results tabulated below.
EXAMPLE In this example, a lubricant was applied to two different polyester fiber types, that is, type 1 and type 2 in the table. The application of the lubricant to the fiber was done by a method designed to lubricate each fiber to a predetermined or known percent level. The fiber samples so lubricated were tested by using the Soxhlet ether extraction method and by using the titration method of this invention. The titration was done with alcoholic KOH, about 0.07 N, into dry isopropanol solvent. The indicator mixed with the isopropanol solvent, to form the fluid circulation system medium, was 1 mg. er liter of a mixture of three parts of phenolphthalein and one part of thymol blue. The titration apparatus was operated as above described, and the results are tabulated in the following table.
MEASUREMENT OF PERCENT OIL 0N POLYESTER FIB ERS Standard Mean values deviation Ether Ether Preset Titraextrac- Titraextraclevel tion tion tion tion It will be noted from the table that the mean values obtained through use of the titration method and appara tus of this invention agree more closely with the preset values than do those obtained by the Soxhlet ether extraction method. Reproducibility of the test values, as shown by the standard deviation, is appreciably better for the tests run in the titration method and apparatus of this invention than it is for the Soxhlet ether extraction method. In addition, data such as the above is obtainable in less than three minutes after receiving the unweighed samples when the titration method and apparatus of this invention are used. Thus, not only does the titration method and apparatus of this invention provide a more eflicient and rapid determination of percent oil on synthetic fibers, it does so with increased accuracy.
The invention may be embodied in other specific forms than that described hereinabove without departing from the spirit or essential characteristics thereof. Therefore, the present embodiment is to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
What is claimed and desired to be secured by United States Letters Patent is:
1. The method of determining the quantity of lubricant oil coated on a fiber, said lubricant oil carrying a titratable analyte therein; comprising the steps of (a) exposing a sample of said fiber to a liquid solvent medium, and
(b) titrating said analyte present in said liquid solvent medium after it has been exposed to said fiber sample.
2. The method according to claim 1 wherein the exposing of said sample to said liquid solvent medium includes circulating said liquid solvent medium in a closed loop circulation system, said sample being held relatively constant within said circulating medium.
3. The method according to claim 2 further comprising the step of forcing a titrant under pressure into said closed loop circulation system until an endpoint is reached.
4. The method of determining the quantity of lubricant oil coated on a fiber, said lubricant oil carrying a titratable analyte therein; comprising the steps of (a) introducing a fiber sample of known weight mm a liquid medium,
(b) vigorously agitating said liquid medium, and
(c) adding a titrant to said liquid medium until the endpoint of the titration is reached.
5. The method of claim 4 wherein said vigorous agitation to said liquid medium is accomplished by circulating said liquid medium past said sample.
6. The method of claim 4 wherein said liquid medium is anhydrous.
7. The method of claim 6 wherein said liquid medium is anhydrous isopropanol.
References Cited UNITED STATES PATENTS 2,161,453 6/1939 Busby et a1. 23253 2,192,614 3/1940 Mackenzie 23253 XR 2,627,453 2/1953 Sheen 23253 2,950,178 8/1960 Halfter 23-253 3,186,800 6/1965 Strickler 23253 US. Cl. X.R. 23253; 73-159