WO1997020813A1 - Process for depolymerizing nylon-containing waste to form caprolactam by superheated steam in the absence of catalysts - Google Patents
Process for depolymerizing nylon-containing waste to form caprolactam by superheated steam in the absence of catalysts Download PDFInfo
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- WO1997020813A1 WO1997020813A1 PCT/US1996/019802 US9619802W WO9720813A1 WO 1997020813 A1 WO1997020813 A1 WO 1997020813A1 US 9619802 W US9619802 W US 9619802W WO 9720813 A1 WO9720813 A1 WO 9720813A1
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- caprolactam
- nylon
- pressure
- polycaprolactam
- atm
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D201/00—Preparation, separation, purification or stabilisation of unsubstituted lactams
- C07D201/02—Preparation of lactams
- C07D201/12—Preparation of lactams by depolymerising polyamides
Definitions
- the present invention relates to a process for the depolymerization of nylon-containing waste to form caprolactam.
- nylon 6 scrap in other words, nylon 6 polymer that is substantially free of non-nylon 6 materials
- nylon 6 is depolymerized by heating at elevated temperatures, usually in the presence of a catalyst and/or steam.
- a catalyst and/or steam See U.S. Patents 4, 107, 1 60; 5,233,037; 5,294,707; 5,359,062; 5,360,905; 5,468,900; and Example 5 of European Patent Application 608,454.
- the caprolactam produced may be removed as a vapor stream as taught by AlliedSignal's U.S. Patent 3, 1 82,055.
- An extensive review of the field has been given by L. A. Dmitrieva et al, Fibre Chemistry, Vol. 1 7, No. 4, March 1 986, pp. 229-241 .
- nylon 66 which is substantially free of non-nylon 66 materials, is depolymerized by hydrolysis as taught by U.S. Patents 4,578,510; 4,605,762; and 4,620,032.
- U.S. Patent 5,266,694 teaches that a mixture of nylon 6 and nylon 66 may be depolymerized by use of a catalyst.
- U.S. Patent 5,310,905 teaches that a mixture of nylon 6 and nylon 66 is first separated from consumer waste, e.g. used carpet or carpet scrap, by extraction with aliphatic carboxylic acid; the filtrate comprising the acid and extracted nylon 6 and nylon 66 is then depolymerized.
- U.S. Patent 5,241 ,066 teaches that a mixture of nylon 6 and PET, which is acid insoluble, is mixed with acid so that the dissolved nylon 6 may be removed from PET; the removed nylon is then depolymerized.
- AlliedSignal's U.S. Patent 3,31 7, 51 9 teaches that a yarn blend of nylon 6 and PET may be depolymerized by heating with aqueous alkali metal hydroxide at elevated pressure.
- Carpets include a face fiber that is adhered to a backing (support) material which may include jute, polypropylene, latex (such as a styrene-butadiene rubber (SBR)) and a variety of inorganic materials such as calcium carbonate, clay, or hydrated alumina fillers.
- SBR styrene-butadiene rubber
- Nylon 6 is often used for the face fiber.
- carpet typically, carpet comprises about 20-55 percent by weight face fiber and 45-80 percent by weight backing materials.
- the fiber contains dyes, soil repellents, stabilizers, and other compounds added during fiber and/or carpet manufacture.
- Waste carpet may also contain a host of other impurities, which will collectively be referred to herein as "dirt" .
- non-nylon 6 components interfere with caprolactam recovery.
- alkaline components such as the calcium carbonate filler
- acidic catalysts such as phosphoric acid
- polypropylene and latex partially decompose to a mixture of hydrocarbons that co- distill with caprolactam. The remaining, partially decomposed, non- distilled portion, along with the filler and other inorganic components, renders the reaction mixture very viscous and difficult to process in conventional equipment.
- Example 3 of each publication a carpet was depolymerized without prior mechanical separation of the backing; steam and 85% phosphoric acid were used respectively at the rate of 51 and 0.30 parts per part of crude caprolactam produced. (The yield of caprolactam was not stated.) It is evident that the high expenditure of steam and phosphoric acid, and the low yield of caprolactam, render this process economically unattractive. Examples 4 and 5 of WO 94/06763 report higher yields of caprolactam, but initial separation techniques to reduce the amount of CaC0 3 prior to depolymerization were required. US Patent 5,455,346 describes a process applicable to the recovery of caprolactam from mixtures containing nylon 6, including nylon 6 carpets.
- Example 13 teaches that the carpeting was freed from polyamide-free components until the polycaprolactam was 75 percent by weight based on the mixture. In contrast, it is often desirable to avoid such separation techniques.
- the invention provides another process for depolymerizing multi-component waste material comprising polycaprolactam and non- polycaprolactam components to form caprolactam which avoids the problems associated with the previous recovery methods.
- the process comprises the step of: in the absence of added catalyst, contacting the multi-component waste material with superheated steam at a temperature of about 250°C to about 400°C and at a pressure within the range of about 1 atm to about 100 atm and substantially less than the saturated vapor pressure of water at the temperature wherein a caprolactam-containing vapor stream is formed.
- the multi-component waste material is contacted for a short time period with liquid water under elevated temperatures and pressures prior to contacting with steam as discussed above.
- the multi-component waste material is nylon 6 carpet.
- FIG. 1 is a graph illustrating one advantage of the invention.
- multi-component, nylon 6 waste material denotes material or articles that include nylon 6 and at least one other component which may be a non-hydrolyzable polymer, an inorganic or organic material, or other types of materials, and that has been, is intended to be, or otherwise would have been discarded by a consumer, manufacturer, distributor, retailer, installer and the like.
- the other components can constitute from about 5 to about 95, preferably about 20 to about 80 weight percent of the multi- component, nylon 6 waste material.
- Multi-component, nylon 6 waste material does not include waste material composed solely of scrap nylon 6 polymeric and/or oligomeric material, such as material generated during the production of intermediate articles such as fiber, chip, film or molded articles which intermediate articles are then incorporated or transformed into end use multi-component products such as carpets and packaging.
- scrap material are yarn waste, chip waste, or extruder slag.
- the multi-component nylon 6 waste material comprises up to a total of about 10 percent by weight with respect to polycaprolactam of at least one of polyhexamethylene adipamide (hereinafter “nylon 66") and polyethylene terephthalate (hereinafter "PET").
- the multi-component nylon 6 waste material may comprise up to a total of about 10 percent by weight with respect to polycaprolactam of nylon 66, PET, or a mixture of nylon 66 and PET.
- “multi-component, nylon 6 waste material” may be referred to as “multi-component waste material” hereafter.
- the foregoing weight percentages exclude the presence of dirt, a previously defined term.
- a preferred embodiment is the recovery of caprolactam from waste carpet material that includes nylon 6 face fiber and non-nylon 6 components.
- fiber denotes an elongated body, the length dimension of which is much greater than the transverse dimensions of width and thickness. Accordingly, “fiber” includes, for example, monofilament, multifilament yarn (continuous or staple), ribbon, strip, staple and other forms of chopped, cut or discontinuous fiber, and the like having regular or irregular cross-sections. “Fiber” includes a plurality of any one of the above or a combination of the above.
- carrier material denotes carpet which has not been subjected to any mechanical separation (referred to herein as “whole carpet”), as well as any mixture of carpet components that is a product of separation, mechanical or otherwise, of whole carpet (referred to herein as “beneficiated carpet”) .
- Waste carpet material denotes carpet material that has been, is intended to be, or otherwise would have been discarded by a consumer, manufacturer, distributor, retailer, installer and the like.
- caprolactam is formed by contacting the multi-component waste material with superheated steam at elevated temperatures and atmospheric or higher pressures and removing a vapor stream containing caprolactam from the contact region.
- superheated steam as used herein means steam that is heated to a temperature substantially higher than the temperature at which condensation to liquid water would take place at the pressure used to convey said steam.
- a further benefit is that even a feedstock composed substantially of whole carpet can be employed in the process, with sufficient yields of caprolactam. This avoids the need for separation processes, to remove various components in carpet, prior to depolymerization.
- nylon 66, PET, or a mixture of nylon 66 and PET is present in the multi-component waste material in an amount of up to a total of 10 percent by weight with respect to nylon 6, these polymers do not interfere with the present depolymerization process or subsequent purification procedures involving distillation of caprolactam. This is an added advantage of the present process, because in carpet recycling, it is virtually certain that small quantities of nylon 66 and PET carpet will find their way in the nylon 6 carpet feedstock. In contrast, in nylon 6 depolymerization processes that rely on liquid phase depolymerization (see U.S.
- Patents 5,359,062 and 5,455,346) the caprolactam produced in solution is sensitive to polymerization initiated by the adipic and terephthalic acids produced by hydrolysis of said polymers. Therefore, such processes must employ low temperature methods, such as extraction, for caprolactam purification, or they must be coupled with post-depolymerization procedures, such as in AlliedSignal's U.S. Patent 5,457, 197 to Sifniades et al.
- the multi-component waste material is preferably fed to the reactor as a melt.
- This feeding may be achieved by using an extruder, gear pump, or other means known in the art.
- Some feeding systems, such as extruders allow the development of relatively high pressures in the melt. This offers the option of contacting the melt with liquid water at elevated temperatures for a short period of time at little added cost. This may be achieved, for example, by introducing water under pressure in the extruder barrel. The contact time between the melt and water may be extended by placing a high pressure pipe between the extruder exit and reactor.
- the multi-component waste material is combined with liquid water and heated at a sufficient temperature for a time period sufficient to effect an initial depolymerization of the polycaprolactam.
- the depolymerization products formed in this step may include reduced molecular weight polycaprolactam, caprolactam, caprolactam linear oligomers, and caprolactam cyclic oligomers.
- Such contact accelerates caprolactam production in subsequent process steps as disclosed in AlliedSignal's U.S. Patent 5,457, 1 97 to Sifniades et al.
- the disclosure of AlliedSignal's U.S. Patent 5,457, 1 97 is incorporated herein by reference.
- caprolactam For the recovery of caprolactam to be economical, it is desirable to utilize as inexpensive equipment and as little steam as technically feasible.
- a good index of the economy of the process is the concentration of caprolactam obtained in the overheads, which bears an inverse relationships to the amount of steam used. Concentrations in excess of 15 wt. % can be obtained by appropriate design of the reactor and choice of operating conditions as described below.
- the reaction temperature should be at least about 250°C but not higher than about 400°C.
- rate of caprolactam formation increases with increasing temperature.
- rate of side reactions of nylon 6 such as evolution of ammonia also increases with temperature and so does the rate of reactions of the non-nylon 6 components of the multi-component material.
- Temperatures of at least about 250°C are preferred because below 250°C, caprolactam formation may be too slow. Temperatures no greater than about 400°C are preferred, as above 400°C side reactions of nylon 6 and reactions of the non-nylon 6 components may become prohibitively fast.
- a preferred temperature range is about 280°C to about 350°C, more preferably a temperature in the range of about 300°C to about 340°C.
- the pressure should be at least atmospheric but higher pressures offer certain advantages as will be explained below. Other factors, such as the availability and operating cost of high pressure equipment may influence the choice of pressure.
- the optimal pressure is well below the saturated vapor pressure of water at the operating temperature.
- the saturated vapor pressure of water is 1 1 1 atm at 320°C, and 144 atm at 340°C. Therefore, it is clear that in the current process, no liquid aqueous phase is present.
- caprolactam concentration at constant steam flow is matched by its effect on the rate of production of caprolactam. Therefore, operating near the optimal pressure minimizes not only steam usage but also reactor volume.
- a further benefit of operating close to the optimal pressure is the suppression of side reactions leading to ammonia formation.
- caprolactam is generally formed by cleavage of caprolactam molecules from the ends of the nylon 6 chain, in a reversal of the polyaddition reaction which constitutes caprolactam polymerization. Water promotes caprolactam formation by virtue of promoting the cleavage of amide bonds, which results in the formation of more end groups.
- caprolactam concentration in the overheads can result in an increase or a decrease of caprolactam concentration in the overheads, depending on whether the caprolactam vapor pressure increases faster or slower than the water vapor pressure.
- the caprolactam partial pressure increases faster than the partial pressure of water as the reactor pressure is increased.
- the partial pressure of water increases faster than the partial pressure of caprolactam as the reactor pressure is increased.
- a secondary effect of pressure is the suppression of caprolactam cyclic dimer.
- the dimer is formed reversibly along with caprolactam during nylon 6 depolymerization.
- relatively large amounts of the dimer are found in the overheads, as much as 3- 4 wt% of the caprolactam.
- Increasing the pressure decreases the ratio of dimer to caprolactam in the overheads. Since dimer formation is reversible, dimer that does not distill over is converted eventually to caprolactam. Suppressing dimer concentration in the overheads is beneficial not only from the point of view of product yield, but also because the dimer, when present at high concentrations, may be deposited as a solid and clog the transfer lines and the condenser.
- the operating pressure should range from about 1 atm up to about 100 atm (about 1 01 kPa to about 101 30 kPa) .
- the pressure should be substantally less than the saturation vapor pressure of water under the operating temperature to ensure that liquid water does not condense in the reactor.
- the saturated vapor pressure of water is 85 atm.
- Operation at that temperature should be carried out at pressures ranging from about 1 atm to about 75 atm.
- the preferred pressure range is about 1 atm to about 30 atm (about 101 kPa to about 3940 kPa).
- the preferred pressure range is about 3 atm to about 1 5 atm (about 304 kPa to about 1 520 kPa) .
- the rate of steam flow should be sufficient to remove caprolactam from the reactor, but not so high as to cause undue dilution of caprolactam in the overheads. Since a high caprolactam concentration in the overheads is desired, the steam flow should be proportional to the rate of production of caprolactam, which is generally proportional to the mass of nylon 6 charged and also increases with temperature.
- the contact of the multi-component waste material with steam is effected in a vessel designed to withstand the requisite temperature and pressure, as well as the corrosiveness of the reactants. Since no corrosive catalysts, such as acids, are required in this process, no special alloys are required, and a stainless steel vessel is adequate.
- Good contact between steam and the multi-component waste material is essential for an effective operation.
- Such contact may be achieved by various means known generally in the art.
- steam may be sparged through the material using a multiplicity of inlets, for example, using a steam distributor.
- Improved contact may be achieved by including mechanical agitation in the reactor, for example, using a combination of rotating paddles and static fins.
- the process of the current invention may be carried out either continuously or in batch fashion.
- the multi- component waste material is charged to the reactor all at once and steam is sparged continuously until most of the caprolactam has been recovered.
- caprolactam concentration in the overheads diminishes as the charge is depleted of nylon 6. Said concentration may be maintained at relatively high levels throughout the process by gradually increasing the temperature and/or decreasing the steam flow as the run process.
- both the multi-component waste material and the steam are fed continuously to the reactor.
- Caprolactam is recovered overhead, while a nylon 6 depleted melt is discharged from the bottoms.
- CSTRs continuous stirred reactors
- the steam flow to each reactor may diminish as the nylon content of the melt diminishes.
- crossflow may generally result in higher overall consumption of steam, it is simpler to implement and may require lower capital investment.
- nylon 6 carpet melt is fed at the top of a continuous flow reactor.
- Superheated steam is fed through a distributor at the bottom of the reactor countercurrent to the flow of the melt.
- a vapor stream containing caprolactam is collected at the top of the reactor and nylon 6 depleted melt exits at the bottom.
- the carpet may be fed by means of an extruder, gear pump, or other device.
- the reactor may be divided into several stages by means of baffles. Means may be provided for mechanical agitation in each stage. Heat is provided to the reactor mainly by means of the superheated steam. Additional heat may also be provided through the carpet feed, especially if an extruder is used to feed the carpet, and through the wall of the reactor.
- Caprolactam may be separated from other components of the distillate.
- the vapors from the reactor overhead may be sent to a partial condenser to obtain a condensate containing caprolactam.
- Fiber grade caprolactam may be obtained from this condensate by further purification including distillation, crystallization and other conventional techniques known in the art.
- the caprolactam purification process of AlliedSignal's U.S. Patent 2,81 3,858; 3,406, 1 76 or 4,767,503 to Crescentini et al. may be used.
- the purified caprolactam may then be used to make polycaprolactam using a known process such as disclosed in AlliedSignal's U.S.
- the polycaprolactam may then be used in known engineered materials such as disclosed in AlliedSignal's U.S. Patent 4, 1 60,790; 4,902,749; or 5, 1 62,440 or spun into fiber using a known process such as disclosed in AlliedSignal's U.S. Patent 3,489,832; 3, 51 7,41 2; or 3,61 9,452.
- EXAMPLE 1 Whole carpet feedstock containing 57.6% by weight nylon 6 was prepared by extruding a shredded carpet having nylon 6 face fiber and backing of polypropylene and calcium-filled SBR and grinding the extrudate to 5 mesh chips. A 178.8 g portion of the feedstock was placed in a cylindrical stainless steel reactor of 24.5 mm diameter and 1070 mm height. The reactor was connected to a condenser equipped with a back-pressure valve at the exit set at 9.2 atm (932 kPa). Superheated steam was blown through the bottom of the reactor at the rate of 3 g/min while the temperature of the reactor was maintained at 300°C.
- Example 1 Several more examples were carried out using the same feedstock and apparatus as in Example 1 . In all cases, the charge was 1 80 _+, 2 g. The results are summarized in Table 1 below. It is seen that increasing the temperature at essentially constant pressure and steam rate, the maximum concentration of caprolactam in the overheads increases (Examples 1 and 4); increasing the pressure at constant temperature and steam rate increases the caprolactam concentration until an optimal level of pressure is reached, and decreases the yield of caprolactam cyclic dimer (Examples 2-5) ; and increasing the steam rate at constant temperature and pressure decreases the caprolactam concentration but increases the caprolactam yield (Examples 4 and 6).
- Example 7 shows that high caprolactam concentration can be achieved at increased steam flow by simultaneously increasing the temperature and pressure.
- FIG. 1 The effect of pressure on the rate of caprolactam production is demonstrated in Figure 1 , in which the cumulative amount of caprolactam in the overheads is plotted as a function of time for Examples 2-5, in which the temperature and the steam flow were held constant at 320 °C and 3 g/min respectively.
- the curves are labeled by the number of the Example to which they refer. It is seen that as the pressure is increased from atmospheric (Example 2) to 6.1 atm (Example 3), the rate increases by more than a factor of two. Further increase in pressure to 10.9 atm (Example 4) produces a smaller increase in rate.
- EXAMPLE 8 A carpet having nylon 6 face fiber and backing of polypropylene and calcium-filled SBR contained about 52% by weight nylon 6. The carpet was cut to strips and about 850 g thereof were charged to a 2 liter stirred autoclave via an extruder. Superheated steam was sparged at the bottom of the autoclave at the rate of 20 g/min while a vapor stream containing caprolactam flowed overhead and was fed to a partial condenser. A condensate containing up to 80% by weight caprolactam was collected. The temperature and the pressure in the autoclave were maintained at 31 2 °C and 9.2 atm respectively during the run.
- the yield of caprolactam in the collected overheads was about 50% by weight of the nylon charged. At the end of three hours, the yield was over 90% based on the nylon 6 in the starting material.
- the condensate was filtered through filter-aid to remove a small amount of oils and suspended waxes and submitted to fractional distillation under vacuum. A fraction containing over 99% caprolactam was obtained. Less than 10% of the available caprolactam remained in the distillation bottoms.
- the distilled caprolactam was further purified via crystallization from water to yield fiber quality caprolactam.
- the caprolactam from Example 8 is spun into fiber using a known spinning process.
- Example 8 The procedure of Example 8 was repeated, except that nylon 66 chips corresponding to about 5% by weight to the nylon 6 present in the carpet were charged to the autoclave along with the carpet. The rate and selectivity of the depolymerization paralleled that of Example 8. Fractional distillation of the collected overheads produced a fraction containing over 99% caprolactam, and less than 10% of the available caprolactam remained in the distillation bottoms.
- EXAMPLE 1 1 The procedure of Example 10 was repeated, except that polyethylene terephthalate chips were substituted for the nylon 66 chips. Comparable results to Example 10 were obtained.
- COMPARATIVE EXAMPLE A One part of a mixture of nylon 6 and nylon 66 chips in the weight ratio 95:5 and 6.67 parts of water were placed in a sealed autoclave and heated under autogenous pressure to 300°C for one hour. Analysis of the resulting solution revealed that about 75% of nylon 6 had been converted to caprolactam. Because caprolactam polymerizes with the mixture of nylon 6 oligomers and nylon 66 oligomers, only a small portion of the caprolactam can be recovered.
- Comparative Example B The procedure of Comparative Example A was repeated, except that polyethylene terephthalate chips were substituted for the nylon 66 chips. Comparable results to Comparative Example A were obtained.
- the apparatus comprises at least three reactors equipped with inlet at the top and outlet at the bottom for liquid flow, and inlet at the bottom and outlet at the top for vapor flow.
- the three reactors are connected in series so that liquid flow runs in one direction while vapor flow runs in the opposite direction.
- Each reactor is equipped with a mechanical agitator and baffles that ensure intimate mixing between liquid and vapor.
- Waste carpet containing about 50% nylon 6 is shredded and fed to an extruder.
- the extrudate is continuously fed to the first reactor and exits from the last.
- Superheated steam is fed to the last reactor at a rate approximately 3 times the extrudate flow and exits from the first reactor.
- the reactors are held at about 330°C and 1 2 atm.
- the overall residence time of the melt in the reactors is about 4 hours.
- the exit vapors are sent to a partial condenser where a condensate containing about 90% caprolactam is obtained.
- Fiber grade caprolactam may be obtained from this condensate by further purification including filtration, distillation, crystallization and other conventional techniques known in the art. A portion of the remaining vapor is purged while the rest is mixed with makeup steam, sent to a superheater, and recycled through the process.
- the caprolactam from Example 1 2 is used to make an engineered plastic.
Abstract
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Priority Applications (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CA002239283A CA2239283C (en) | 1995-12-08 | 1996-12-06 | Process for depolymerizing nylon-containing waste to form caprolactam by superheated steam in the absence of catalysts |
ES96943716.9T ES2185813T5 (en) | 1995-12-08 | 1996-12-06 | Process to depolymerize residues containing nylon to form caprolactam by means of superheated steam in the absence of catalysts |
DE69624378.4T DE69624378T3 (en) | 1995-12-08 | 1996-12-06 | PROCESS FOR DEPOLYMERIZING NYLON-CONTAINING WASTE TO CAPROLACTAM WITH OVERHEATED WATER VAPOR IN THE ABSENCE OF CATALYSTS |
EP96943716.9A EP0874817B2 (en) | 1995-12-08 | 1996-12-06 | Process for depolymerizing nylon-containing waste to form caprolactam by superheated steam in the absence of catalysts |
JP9521499A JPH11511485A (en) | 1995-12-08 | 1996-12-06 | Depolymerization of Nylon-Containing Waste Material Forming Caprolactam |
HK99101393A HK1016181A1 (en) | 1995-12-08 | 1999-04-07 | Process for depolymerizing nylon-containing waste to form caprolactam by superheated steam in the absence of catalysts |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/569,640 US5681952A (en) | 1995-12-08 | 1995-12-08 | Process for depolymerizing nylon-containing waste to form caprolactam |
US08/569,640 | 1995-12-08 |
Publications (1)
Publication Number | Publication Date |
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WO1997020813A1 true WO1997020813A1 (en) | 1997-06-12 |
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Application Number | Title | Priority Date | Filing Date |
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PCT/US1996/019802 WO1997020813A1 (en) | 1995-12-08 | 1996-12-06 | Process for depolymerizing nylon-containing waste to form caprolactam by superheated steam in the absence of catalysts |
Country Status (11)
Country | Link |
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US (4) | US5681952A (en) |
EP (1) | EP0874817B2 (en) |
JP (1) | JPH11511485A (en) |
CA (1) | CA2239283C (en) |
DE (1) | DE69624378T3 (en) |
ES (1) | ES2185813T5 (en) |
HK (1) | HK1016181A1 (en) |
MX (1) | MX9804433A (en) |
MY (1) | MY113539A (en) |
TW (1) | TW408110B (en) |
WO (1) | WO1997020813A1 (en) |
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Also Published As
Publication number | Publication date |
---|---|
US5929234A (en) | 1999-07-27 |
EP0874817B1 (en) | 2002-10-16 |
ES2185813T3 (en) | 2003-05-01 |
EP0874817A1 (en) | 1998-11-04 |
US6342555B2 (en) | 2002-01-29 |
MX9804433A (en) | 1998-12-31 |
EP0874817B2 (en) | 2015-12-02 |
US5932724A (en) | 1999-08-03 |
ES2185813T5 (en) | 2016-03-23 |
CA2239283A1 (en) | 1997-06-12 |
CA2239283C (en) | 2004-10-19 |
US20010001792A1 (en) | 2001-05-24 |
DE69624378T2 (en) | 2004-06-24 |
US5681952A (en) | 1997-10-28 |
DE69624378D1 (en) | 2002-11-21 |
JPH11511485A (en) | 1999-10-05 |
MY113539A (en) | 2002-03-30 |
TW408110B (en) | 2000-10-11 |
DE69624378T3 (en) | 2016-04-21 |
HK1016181A1 (en) | 1999-10-29 |
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