US007259231B2

(12) United States Patent (10) Patent N0.: US 7,259,231 B2 Cornish et a]. (45) Date of Patent: *Aug. 21, 2007

(54) EXTRACTION AND FRACTIONATION OF 3,812,012 A 5/1974 Buschmann et al. BIOPOLYMERS AND RESINS FROM PLANT 3,972,775 A 8/1976 Wilke et al. MATERIALS 3,990,944 A 11/1976 Gauss et a1. 3,990,945 A 11/1976 Huff et al. (75) Inventors: Katrina Cornish, Vista, CA (US); i is??? t l Je?rey A. Martin, Carlsbad, CA (US); 4’094’742 A 61978 Bell? e a' Rodger T. Mlarentis, Macungie, PA 430973333 A @1978 Freytagyet 31‘ (US); Sebastian Plamthottam, Upland, 4,104,409 A 8/1978 Vitzthum et a1‘ CA (US) 4,684,715 A 8/1987 Kay et a1. 5,171,592 A * 12/1992 HoltZapple et al...... 426/69 (73) Assignee: Yulex Corporation, Maricopa, AZ (US) 5,849,854 A * 12/1998 Noda ...... 528/1 6,054,525 A 4/2000 Schloman, Jr. et al. ( * ) Notice: Subject to any disclaimer, the term of this 6,569,375 B1 5/2003 McGlothliIl et al patent is extended or adjusted under 35 6,623,600 B1 9/2003 HeIlflkSeIl USC 154 (b ) b y 0 d ays . FOREIGN PATENT DOCUMENTS This patent is subject to a terminal dis- JP 4464035 * 9/1992 Clalmer- JP 9-143489 * 6/1997 (21) Appl. No.: 11/249,884 OTHER PUBLICATIONS (22) Filed, Oct 12, 2005 Fu1resin containing plant _ _ 299/21’ 133 materials, using supercritical solvent extraction, for example See apphcanon ?le for Complete Search hlstory' supercritical carbon dioxide extraction. Additionally, polar (56) References Cited and/or non-polar co-solvents can be used With supercritical carbon dioxide to enhance the selective extraction of resins U.S. PATENT DOCUMENTS and rubbers from the shrub. 3,616,222 A 10/1971 Dasinger 3,806,619 A 4/1974 Zosel 38 Claims, No Drawings US 7,259,231 B2 1 2 EXTRACTION AND FRACTIONATION OF Further, using traditional methods of guayule processing, BIOPOLYMERS AND RESINS FROM PLANT plant material is prepared by initially grinding it into small MATERIALS particles. Generally, the entire plant is fed Whole, that is, With the leaves thereon as Well as dirt or foreign debris, into CROSS REFERENCE TO RELATED a grinding apparatus, for example, a hammermill. The APPLICATIONS ground material can be ?aked, that is crushed, by adding to a tWo-roll mill or other conventional equipment, Which This Application claims the bene?t of priority of US. ruptures the rubber-containing cells. The communited plants Provisional Application Ser. No. 60/618,167, ?led Oct. 12, are subjected to a resin-rubber solvent system. The solvent 2004. system contains one or more solvents Which extract the resin as Well as the rubber from the guayule-type shrub. Examples FIELD OF THE INVENTION of single-solvent systems include halogenated hydrocarbons having from 1 to 6 carbon atoms, such as chloroform, This invention relates in general to the extraction, sepa perchloroethylene, chlorobenZene, and the like; and aro ration, fractionation and puri?cation of resins and biopoly matic hydrocarbons and alkyl-substituted aromatic hydro mers from plant materials using supercritical solvent extrac carbons having from 6 to 12 carbon atoms, such as benZene, tions. Speci?cally, the invention relates to a process for the toluene, xylene, and the like. separation of resins and rubber from the guayule shrub This solvent system typically contains one or more polar (Parlhenium argenlalum) using supercritical solvent extrac resin solvents as Well as one or more hydrocarbon rubber tion, for example, supercritical carbon dioxide extraction. 20 solvents. Typical polar resin solvents include alcohols hav Additionally, co-solvents can be used With supercritical ing from 1 to 8 carbon atoms, such as methanol, ethanol, carbon dioxide to enhance the selective extraction of resins isopropanol and the like; esters having from 3 to 8 carbon and rubbers from the plant material. Finally, subcritical atoms such as the various formates, the various acetates and Water extraction may also be used according to this inven the like; ketones having from 3 to 8 carbon atoms, such as tion. 25 acetone, methyl ethyl ketone, and the like. Typical non-polar hydrocarbon rubber solvents include alkanes having from 4 BACKGROUND OF THE INVENTION to 10 carbon atoms, such as pentane, hexane, and the like; and cycloalkanes having from 5 to 15 carbon atoms, such as cyclohexane, decalin, the various monoterpenes, and the Guayule is a desert shrub native to the southWestern 30 like. Although the tWo types of solvents can form a tWo United States and northern Mexico and Which produces phase system, they often form a single phase When utiliZed polymeric isoprene essentially identical to that made by in proper proportions. One manner of adding different type Hevea rubber trees (e.g., Hevea brasiliensis) in Southeast solvents to the shrub is separately, but simultaneously. Asia. As recently as 1910 it Was the source of half of the HoWever, they are generally prepared as a mixture and natural rubber used in the US. Since 1946, hoWever, its use 35 added as such. as a source of rubber has been all but abandoned in favor of Accordingly, numerous combinations of a polar resin cheaper Hevea rubber and synthetic rubbers. HoWever, solvent and a hydrocarbon rubber solvent can exist. A demand for natural rubber is expected to produce shortages speci?c solvent system is an aZeotropic composition of of that material in the future and rubber prices are expected approximately 80% by Weight of pentane, more speci?cally to rise signi?cantly. Natural rubber having loWer heat hys 40 78.1% by Weight, and 20% by Weight of acetone, more teresis is required for many kinds of tires and amounts to speci?cally 21.9% by Weight. The ratio by Weight of solvent about 35% of US. rubber use. to the amount of shredded shrub can be any amount su?i As an alternative to synthetic rubber sources, attention is cient to generally extract most of the rubber and resin, as for being directed to the production of hydrocarbons in plants example from about 1 part by Weight of solvent up to about such as guayule (Parlhenium argenlalum). Guayule nor 45 20 parts by Weight of solvent for each 1 part by Weight of mally yields one half ton to one ton of rubber per acre in shrub, and preferably about 3 parts by Weight of solvent to cultivation When, after tWo years, the entire plant is har 1 part by Weight of shrub. The rubber-resin miscella so vested and processed. Guayule plants store latex in tiny obtained typically contains about 1 to 25% by Weight of total inclusions in the bark, making harvest of the outer ?brous solids, that is resin plus rubber, and preferably about 9 to layers, or bagasse, of the plant, desirable. 50 18% by Weight of total solids With the amount of resin by Using traditional techniques, as much as 95% of the Weight being from about 1 to about 3 parts for every 1 part available natural rubber may be recovered from plant mate by Weight of rubber. rials, using parboiling, Which coagulates the latex in the Furthermore, traditional methods of plant processing have cells, folloWed by a milling step in a caustic solution to been hampered by the use of these highly toxic compounds release the rubber. This traditional process then causes the 55 and cumbersome processes. For example, in prior industrial milled bagasse to sink to the bottom of the processing vessel operations, hexane and heptane solvents have been used in and alloWs resin to ?oat to the surface for collection. More the solvent extraction of oil-containing vegetable matter. speci?cally, in traditional processes, resins from plant mate The extraction apparatus typically includes vertical extrac rials are obtained by solvent extraction With polar solvents tion toWers, screW extractors and bucket extractors. With such as alcohols, ketones, and esters. A commonly used 60 current equipment, several extraction stages are necessary in solvent for extracting the guayule resin is acetone. The resin order to circulate the miscella and attain su?icient Wetting of is recovered from the solution by evaporating the solvent. the material to be extracted, thereby requiring the use of a The rubber from the shrub is generally extracted using higher proportion of solvent. hydrocarbon solvents such as hexane, cyclohexane or tolu In addition, overall energy consumption inherent in pre ene. Such processes are normally very expensive and not 65 vious slurry separations has been excessive, if not prohibi environmentally friendly. A Water ?oatation method has also tive. Processing of this type of plant material traditionally been used for the extraction of rubber. requires Wetting to form a liquid slurry, a high amount of US 7,259,231 B2 3 4 heat, and a di?icult separation of the solvent from the biopolymers, such as rubber, from plant materials, such a extracted oil and defatted meal. Complete removal of sol guayule. One embodiment uses supercritical carbon dioxide vents, such as hexane, from the spent botanical residue is for the simultaneous extraction, separation, fractionation practically impossible by conventional steam stripping tech and puri?cation of rubber and resins from guayule plant niques. materials. Alternate embodiments of the present invention The method of using gaseous solvents at both supercriti comprise the steps of resin and rubber extraction With cal and subcritical conditions, such as carbon dioxide and supercritical carbon dioxide, separation, fractionation and propane, is also problematic. In these systems, the operating puri?cation of rubber and resins in succession rather than pressure must exceed 125 psi to remain in liquid state and simultaneously. even higher if temperatures are elevated. Because of the As disclosed herein, the present invention is a method of di?iculties in Working at high pressure, multiple extraction extracting high molecular Weight biopolymers, for example, vessels are required, Which limits the speed and e?iciency of rubber, and resin, from plant material using supercritical these extractions. Further, it is difficult to maintain pressures ?uid at medium to high pressures. In at least one embodi consistently, resulting in freezing, gumming, or poor sepa ment, carbon dioxide gas is compressed into a dense liquid, ration of the extracted materials, Which may clog the system. this liquid is then pumped into a cylindrically-shaped high Also hydrolysis of lipids or inadequate processing may pressure vessel containing the guayule shrub, the extract decrease the yield. laden liquid is then pumped into a separation chamber, In an effort to overcome some of these di?iculties, in Where the extract is separated from the gas, and the gas is recent years cellulose degradation methods using enZymes recovered for reuse. Many variations of these processes and such as pectin hydrolases, cellulose, alkalis, or acids have 20 conditions, as disclosed herein, can be used including dif been taught. In addition, the prior art teaches a number of ferent co-solvent systems and methods of plant material processes for production of glucose from cellulose in the preparation. These Will be apparent to those skilled in the presence of lignin. Crushing and extraction processes for relevant art. hydrocarbon-containing plants have also been taught. HoW While supercritical ?uid extraction processes have been ever, prior art processes have not dealt With the problem of 25 used commercially for the extraction of alkaloids, ?avor obtaining hydrocarbons from hydrocarbon-containing plants components, perfumes and the like, for the reasons articu Wherein the hydrocarbon content is loW and is contained in lated above, this process previously has not been shoWn to laticifer cells. be effective or useful in extracting high molecular Weight Additionally, traditional extraction methods make it dif biopolymers from plant materials as complex as guayule, ?cult and ine?icient to extract resins from plant materials, 30 Which contain thousands of secondary products. particularly from the bagasse. Bagasse is di?icult to extract Rubber is a naturally-occurring hydrocarbon polymer of With hydrocarbon solvents for several reasons. First, the cis-l,4-polyisoprene With 400-50,000 isoprene monomeric compounds of interest are adhered in the botanical matrix, so units enZymatically linked in a head-to-tail con?guration. It the material needs to be ground ?nely for accessibility of the is to be understood that the rubbers from numerous plants, solvent to these compounds. Second, the compounds of 35 such as guayule plants, are de?ned herein as “guayule type” interest are signi?cantly different in polarity, namely, resins rubbers and hence can be utiliZed either alone or in combi are polar and rubber is non-polar. This makes it di?icult to nation With each other. Hereinafter Whenever reference is utiliZe a single solvent system, and therefore, most extrac made to guayule plants or shrubs, it is to be understood that tion processes utiliZe a tWo-solvent extraction system, e.g., the beloW-described plants and shrubs can also be utiliZed. acetone for resin extraction folloWed by cyclohexane for 40 Guayule-type plants Which can be utiliZed to prepare rubber extraction. Third, ground bagasse has physical prop rubber-containing miscellae include guayule, gopher plant erties that translate into very sloW percolation rate for liquid (Euphorbia lalhyris), mariola (Parlhenium incanum), rab solvents. Fourth, contact With oxygen can oxidiZe the rubber bitbrush (Chrysolhanmus nauseosus), candelilla (Pedilan extract in other processes. thus macrocarpus), Madagascar rubbervine (Cryploslegia Thus, it has been di?icult to design a commercially viable 45 grandl?'ora), milkWeeds (Asclepias syriaca, speciosa, subu process for the extraction of bagasse With liquid solvents. lala, et al.), goldenrods (Solidago allissima, graminifolia, Additionally, due to the problems With sloW percolation rate rigida, et al.), Russian dandelion (Taraxacum kok-saghyz), through the bagasse, traditional processing methods have mountain mint (Pycnanlhemum incanum), American ger resulted in a loW commercial output, and much of the unused mander (Teucreum canadense), and tall bell?oWer (Cam bagasse contains residual solvents. The residual solvents in 50 panula americana). Many other plants Which produce rub the remaining bagasse pose environmental safety haZards ber and rubber-like hydrocarbons are knoWn, particularly and make the excess bagasse mostly unusable for other among the Asteraceae (Compositae), Euphorbiaceae, Cam applications. Finally, the loW output makes these prior art panulaceae, Labiatae, and Moraceae families, and hence can extraction processes not commercially viable methods of be utiliZed. extraction. 55 Plant materials may be obtained using a variety of con Therefore, a need exists for a cost-effective, e?icient, and ventional and experimental harvesting processes. Generally, environmentally friendly method of extracting and fraction plants are cultivated, harvested and bailed using standard ating rubber and resins from plant materials, such as farming practices. Various portions of a plant may be used guayule. to obtain plant materials, including leaves, bark, stems, root 60 systems or root balls. DETAILED DESCRIPTION OF THE The plant need not be de-leafed because the metal ions INVENTION such as manganese, iron and copper in the leaves that could promote oxidative degradation of the rubber are not The present invention utiliZes supercritical solvents, such extracted into the rubber solvents. Further, processing the as carbon dioxide, optionally in combination With other 65 plant, including the leaves, may add to the quality of the co-solvents, for the separation, fractionation and puri?cation bagasse because the leaves contain mineral, nitrogenous and of loW molecular Weight resins and high molecular Weight carbohydrate components that could enhance the quality of US 7,259,231 B2 5 6 the bagasse for certain post-processing applications. Further, For example a comparison of typical values for density, in this embodiment of the invention, the process results in viscosity, and diffusivity of gases, liquids and SCF’s is as three products: total shrub rubber, total shrub resin and total folloWs: shrub bagasse. The plants may be processed by de-lea?ng or de-barking TABLE 1 using mechanized shearing or hand shearing, or may be Comparison of physical and transport properties processed With leaves and Washed Without de-lea?ng or of gases liquids and SCFs. de-barking. Removal of the leaves from the harvested shrub prior to the disclosed supercritical extraction process Would Property Density (kg/m3) Viscosity (cP) Diffusivity (mmZ/s) permit the leaf Wax to be isolated and sold separately. Gas 1 0.01 1-10 Defoliation Will also eliminate the Wax as a possible con SCF 100-800 0.05-0.1 0.01-0.1 taminant in the resin and rubber solvents. Liquid 1000 0.5-1.0 0.001 Initial processing of plant materials may consist of a high pressure Water system to strip the bark or leaves off the plant. It is noted that pressure and temperature may be manipu Plant materials may be processed at a processing facility by lated using a combination of isobaric changes in temperature conveyor, and any leftover plant material transported aWay With isothermal changes in pressure. Using SCFs, it is for further re?ning or disposal. Secondary processing prior possible to convert a pure component from a liquid to a gas to extraction may further comprise grinding, hammermill (and vice versa) via the supercritical region Without incur ing, or forcibly fractionating Whole or partial plant materials 20 ring a phase transition. The behavior of a ?uid in the into smaller pieces. The plant material may also be ground supercritical state can be described as that of a very mobile and then pelleted. Plant material may also be pre-treated by liquid, and the solubility behavior approaches that of the either enZymatic degradation of Whole or partial plants. liquid phase While penetration into a solid matrix is facili Optionally, the bagasse may then be further extracted tated by the gas-like transport properties. according to the methods disclosed herein. 25 As a result, the rates of extraction and phase separation The extraction process disclosed herein can be carried out can be signi?cantly faster than for conventional extraction on a large scale using industrial extraction equipment, or on process, and extraction conditions can be controlled much the small scale using a typical laboratory scale units such as better to, further optimiZe separation. SCF extraction is the Spe-ed SFE-2 from Applied Separations, 930 Hamilton knoWn to be dependent on the density of the ?uid, Which in Street, AllentoWn, Pa., 18101. 30 turn may be manipulated through control of the system In the supercritical state, solvents, or supercritical ?uids pressure and temperature. Further, the dissolving poWer of (SCFs), can readily penetrate porous and ?brous materials, SCF increases With isothermal increase in density or an and are particularly Well adapted to processing guayule plant isopyonic (i.e., constant density) increase in temperature. materials. Since the solvating poWers can be adjusted by 35 Under thermodynamic equilibrium conditions, the visual changing the pressure or temperature, separation and frac distinction betWeen liquid and gas phases, as Well as the tionation of resins and rubber is fast and easy. In addition, difference betWeen liquid and gas densities disappear at and fractionation can be improved and extraction enhanced for above the critical point. Similar drastic changes exist in high molecular Weight components by adding modi?ers or properties of a liquid mixture as it approaches the thermo co-solvents, making SCFs a highly-versatile solvent to uti dynamic critical loci of the mixture. This provides the more liZe With improved separation/fractionation capabilities 40 gas-like physical properties of SCF, including thermal con When compared to conventional organic liquid solvent ductivity, surface tension, constant-pressure heat capacity extraction processes. and viscosity, Which are far superior to standard liquids to Generally, SCFs are ?uids that exist at the transition enchance mass transfer during extraction. For example, if comparing a liquid organic solvent With a supercritical ?uid betWeen liquids and gases, and share some qualities of each. 45 A pure SCF is any compound at a temperature and pressure solvent With the same density, the thermal conductivity and above the critical values (e.g., a ?uid is termed ‘super di?‘usity of a SCF are higher and the viscosity is much loWer. critical’ When the temperature and the pressure exceed the Furthermore, With SCFs, surface tension and heat of vapor critical pressure point (CP) of a vapor-liquid coexistence iZation have almost completely disappeared. curve). More speci?cally, a ?uid is termed supercritical 50 Supercritical ?uids are an alternative to organic solvents When the temperature and pressure are higher than the in industrial puri?cation and re-crystalliZation operations, corresponding critical values. The critical temperature of a because they provide a more environmentally-friendly pro ?uid is the temperature above Which liquefaction is not cess and eliminate some of the dangers to Workers that are possible at any pressure. associated With traditional organic methods. SCF-based Critical pressure (“CP”) is further de?ned as the pressure 55 extraction processes do not produce the VOC and ODC required to liquefy a gas at the critical temperature. At emissions that are the by-products of traditional organic temperatures and pressures above those at the critical point, processes. Supercritical ?uids are commonly used to extract ?uids are at supercritical conditions. A supercritical ?uid is analytes from samples. characterized by physical and thermal properties that are For example, supercritical ?uid extraction (SFE) pro betWeen those of the gas and pure liquid. The ?uid density 60 cesses are commonly used in the food industry, e.g., for is a strong function of the temperature and pressure. Above coffee and tea decalfeination and for beer breWing. SCF the critical temperature of a compound, the pure gaseous processes are also used in polymer, pharmaceutical, lubri component cannot be lique?ed regardless of the pressure cant, and ?ne chemical industries and are valued for their applied. The CP is the vapor pressure of the gas at the critical potential to increase product performance levels over tradi temperature. In the supercritical state, only one phase exists. 65 tional processing technologies. In addition, SCFs are used in This phase retains solvent poWer approximating liquids as the recovery of organics from oil shale, separations of Well as the transport properties common to gases. biological ?uids, bio-separation, petroleum recovery, crude US 7,259,231 B2 7 8 de-asphalting and de-Waxing, coal processing, selective More speci?cally, the present invention discloses a extraction of fragrances, oils and impurities, pollution con method of rubber and resin extraction in at least the folloW trol, and combustion. ing alternate and non-limiting Ways: (1) approximately Supercritical ?uids provide the advantage that they are simultaneous extraction of rubber and resin using a super inexpensive, extract the analytes faster and are more envi critical solvent, such as supercritical CO2 Without use of any ronmentally friendly than organic solvents. For example, co-solvents; (2) approximately simultaneous extraction of SCFs have solvating poWers similar to liquid organic sol resin and rubber using a non-polar co-solvent, folloWed by vents but With higher di?‘usivities, loWer viscosity, and fractionation in a supercritical ?uid system, for example, loWer surface tension. The solvating poWer can also be using supercritical CO2, into a rubber fraction and a resin adjusted easily by changing the pressure or temperature for fraction; or (3) high pressure supercritical ?uid extraction at e?icient separation of analytes. According to one embodi a speci?c narroW range of pressure and temperatures to ment, carbon dioxide is used as the supercritical solvent. remove the resin, folloWed by a high pressure solvent Altemately, other supercritical solvents are also used, extraction in the same vessel, With cyclohexane or similar including, but not limited to, ammonia, Water, nitrous oxide, non-polar solvent to remove the rubber; or (4) high pressure xenon, krypton, methane, ethane, ethylene, propylene, pro solvent extraction at a speci?c range of temperature and pane, pentane, methanol, ethanol, isopropanol, isobutanol, pressure With cyclohexane or similar non-polar solvent to chlorotri?uoromethane, mono?uoromethane, cyclohexanol, remove the rubber, folloWed by high pressure supercritical toluene and other solvents knoWn in the art. ?uid extraction at a speci?c narroW range of pressure and Supercritical ?uid carbon dioxide has the gas-like physi temperatures to remove the resin. cal properties of very loW surface tension, loW viscosity and 20 Each of the above alternate embodiments of the disclosed high diffusivity, Which alloW a supercritical ?uid solvent to methods are then each optionally folloWed by a ?nal rinse of supercritical carbon dioxide to remove the residual solvent penetrate an ultra loW porosity substrate, such as a bed of ?nely ground bagasse, in a ?xed bed extractor vessel and from the bagasse. dissolve the compounds of interest. Supercritical carbon Referring noW to the embodiment of the disclosed method dioxide appears to have su?icient polarity at medium to high 25 comprising simultaneous extraction of rubber and resin, the pressures and temperatures to be an adequate solvent of the method comprises a simultaneous resin and rubber extrac resinous materials (but is a poor solvent for the rubber). tion utiliZing supercritical carbon dioxide at speci?c pres Finally, supercritical carbon dioxide, because of its loW sure, preferably betWeen 1500 and 10,000 psi, and more surface tension, loW viscosity and high di?‘usivity, can preferably betWeen 5,000 and 10,000 psi, With a temperature penetrate the bed of ground bagasse at a very high perco 30 range betWeen 60-100o C. An alternate embodiment further lation rate, Which alloWs for a very quick extraction When includes using a non-polar co-solvent, preferably at a co compared to hydrocarbon solvents. Using supercritical CO2 solvent ratio 3-10 times the feedstock Weight, in order to is advantageous over other extraction methods and has the simultaneously extract the resins and the rubber. According potential to be the superior process for resin and rubber to the present disclosure non-polar co-solvents include, but extraction on a commercial scale. 35 are not limited to, hexane, hexene, octane, pentane, cyclo hexane, iso-octane, and 1-hexene. Another embodiment Following initial processing of plant material, described alternately includes using a polar co-solvent, for example, in more detail beloW, the plant material is contacted With Water, ethanol, methanol and acetone. Additionally, the carbon dioxide near or above the supercritical conditions for present disclosure includes a supercritical ?uid extraction a su?icient time to solubiliZe the resin and/or rubber com 40 further including both a polar co-solvent and a non-polar ponents, forming a supercritical solution. As Will be dis co-solvent. closed more fully herein, this is folloWed by a collection The simultaneous extraction is folloWed by a fractionation process in Which the resins and rubber, Which precipitate out step, utiliZing a supercritical ?uid system to fractionate the from the supercritical solution, are collected When the pres material into a rubber fraction and a resin fraction. The sure is reduced to atmospheric level. The pressures used for 45 fractionation is then folloWed by a rinse of pure carbon extraction can range from about 1500 psi to about 10,000 dioxide, Which removes the residual solvent from the psi, depending on the temperature, for the supercritical bagasse. carbon dioxide and for the carbon dioxide With modi?er In an alternate embodiment, high pressure supercritical co-solvent systems. ?uid extraction at a speci?c narroW range of pressure and In another embodiment, the guayule shrub is ?rst 50 temperatures to remove the resin is folloWed by a high extracted With supercritical carbon dioxide at high tempera pressure solvent extraction in the same vessel, With a non tures and pressures and the temperature and pressure con polar solvent to remove the rubber. In another embodiment, ditions are loWered or changed to precipitate the various high pressure solvent extraction is carried out at a speci?c insoluble fractions. In yet another embodiment, fraction range of temperature and pressure With cyclohexane or ation can be carried out by extracting guayule shrub at 55 similar non-polar solvent to remove the rubber, folloWed by different temperatures and pressures, going from loW to high pressure supercritical ?uid extraction at a speci?c high, and collecting each fraction, a novel Way to make narroW range of pressure and temperatures to remove the different melting point resins. Preferably, this method of resin. In yet another embodiment, one or more of the above extraction can be used to fractionate the resins and rubber in processes are then optionally folloWed by a ?nal rinse of a single system and With a single solvent. 60 supercritical carbon dioxide to remove the residual solvent The steps of the disclosed method are capable of being from the bagasse. performed in various orders or, in some cases, as noted, at The removal of the resins and the second extraction is approximately the same time. For example, in one embodi performed under pressure, Which alloWs circumvention of ment, simultaneous extraction of resin and rubber using a the sloW percolation problem, and provides a method non-polar co-solvent is folloWed by fractionation in a super 65 capable of obtaining a high yield of rubber from the product critical ?uid system, for example, using supercritical CO2, With this method. The ?nal rinse With carbon dioxide alloWs into a rubber fraction and a resin fraction. for elimination of the environmental problem. Another ver US 7,259,231 B2 10 sion of this second process utilizes a polar solvent that is The resins Which are extracted from the shrub are also selective for resin such as alcohol or acetone to accelerate recoverable and are a mixture of terpenes, terpenoids, par the removal of the resin and in some cases to suppress the thenoids and glycerides of fatty acids. The resin component extraction of the rubber for an even higher yield and purity also contains a valuable hard Wax similar to carnauba Wax. of resin and rubber fraction. The resins can be used as an adhesive in plyWood and as a The present disclosure also envisions the use of subcriti component in varnishes. Further, resin can also be used as a cal liquid for the extraction process. Many variations of tackifying resin in the manufacture of reinforced composite these process and conditions can be used such as different rubber articles such as tires and car radiator hoses. co-solvent systems, subcritical conditions to extract loW molecular Weight fractions, and the like, and these Will be EXAMPLES apparent to those skilled in the art. Speci?cally though, the subcritical method comprises contacting plant material With The process of extraction of resins and rubber is explained a compressed gas solvent, Wherein the temperature and in the folloWing examples; the examples set forth herein pressure of the solvent are at subcritical liquid conditions; beloW are to be understood as not limiting the disclosure. maintaining the subcritical liquid for a sufficient time, Examples 1-15 disclosed herein are performed according to Wherein the biopolymer and the solvent form a subcritical one or more embodiments of the disclosed method. The liquid solvent solution; and extracting the biopolymer by results of these experiments illustrate the advantages of percolation of the subcritical liquid through a bed of the using the disclosed supercritical extraction method. In order plant material utiliZing an inert percolation aid such as to measure and analyZe the rubber and resin extracts, the diatomaceous earth. 20 ASE (accelerated solvent extraction) method is used to As an additional alternate step, plant material is stored measure the percent rubber and resin extracted using super prior to processing. Speci?cally, a presoaking process is critical solvent extraction according to the present disclo used prior to the supercritical extraction. In this embodi sure. ment, storage comprises mixing the material in communited The ASE system used for determining rubber and resin form With at least one essentially Water-free organic liquid to 25 extracted using the disclosed method comprises the folloW form a slurry in Which the material is protected from contact ing: a polypropylene centrifuge tube, 50 ml, With skirt; With oxygen and then storing said slurry for at least 24 hours. aluminum Weighing dish, 70 mm diameter, With tab; a In this embodiment, the organic liquid may be selected from drying oven, Thelco Model 130DM (or equivalent); a cen (1) alcohols, ethers, esters and ketones having one to eight trifuge, Dynac Model 420101 (or equivalent); an analytical carbon atoms; (2) hydrocarbon solvents having a boiling 30 balance, Mettler Toledo AG 104 (or equivalent) With reso range Within about 20°-100o C.; (3) concentrated resin lution of 0.01 mg; a vacuum oven, VWR Model 1400E (or miscella; (4) hydrocarbon/guayule rubber/guayule resin equivalent); and an Accelerated Solvent Extractor (A.S.E.), miscella; (5) hydrocarbon/guayule rubber miscella compris Dionex Model 200 With solvent controller; extraction cells, ing said hydrocarbon solvent and about 2-4% guayule 11 ml With ?lter discs; Borosillicate vials, 40 ml, With septa rubber, or (6) mixtures thereof. In this embodiment, the 35 and lids; and a coffee grinder. Further, according to one liquid is acetone or acetone/resin miscella and contains a embodiment, the folloWing reagents are used: acetone; stabiliZer such as a para-phenylenediamine stabiliZer. cyclohexane, methyl alcohol; nitrogen; and OttaWa sand. Additionally, the storage of the plant material may com The analysis of the extract begins by placing the plant prise the entire non-defoliated plant and may be dried to a material, such as the Whole guayule shrub, or coarsely or moisture content of about 5-25% before forming the slurry. 40 ?nely ground guayule shrub, in a supercritical ?uid extrac In some embodiments, the slurry is subjected to mild agi tion (SFE) pressure vessel. In one embodiment of the tation. This storage method prevents development of offen invention, the guayule shrub is chopped into small pieces. In sive odors, due to the degradation, as Well as prevents an alternate embodiment, the guayule shrub is shredded or micro?oral groWth on the shrub. This method also alloWs ?nely ground ?rst. communited guayule/organic solvent slurry to be pumped 45 Speci?cally, the sample of plant material is prepared by from one processing unit to another, avoiding undue expo Weighing the entire fresh sample and then cutting the branch sure of the material to air. In addition, the invention permits tissue into 2 cm lengths. The plant material is also reduced partial or essentially complete extraction of useful products through a chipper using a 3/8" round hole screen to achieve from the shrub during storage, thus reducing costs, time and the same particle siZe. Once reduced in siZe, the plant equipment required. 50 material is again Weighed. The plant material is then dried in Another alternate additional step is pretreatment of the a suitable oven at 80° C. Once dried, the plant material is plant material to increase the ef?ciency of the supercritical again Weighed. Next, the plant material is ground in a coffee extraction process and/or increase the yield of rubber and grinder or other suitable apparatus. Then, the sample mate resin produced in the extraction. In one embodiment of the rial is stored in jars or vials in a refrigerator. present invention, the pretreatment step comprises the appli 55 The analysis is performed according to the folloWing cation of a guanidine salt solution to the plant material, to method. First, a 1.5 g prepared plant material sample is soften the plant cell tissue and denature the protein coat that placed into a tared aluminum dish. Second, another dish and surrounds each globule of rubber, in order to facilitate the a centrifuge tube is Weighed for each sample. Third, sand release of rubber into solution. (approximately 2.5-3 g) is mixed With the sample, trans Once the rubber and resin have been extracted, the 60 ferred to a cell (screW on bottom, place a ?lter inside), and bagasse recovered from the solvent extraction process is screW on top of cell. Additional sand is added to ?ll. The top relatively free of Water and could be used as a fuel to supply and bottom are checked for tightness to prevent the run from the poWer requirements of the disclosed system and method, aborting due to solvent leak. or as a separate marketable product. Alternatively, complete The cell is then loaded into top tray of ASE. A “blank” cell hydrolysis of the bagasse can be affected to fermentable 65 (?lled With only sand) is then loaded in the ?rst position. The sugars, Which could be used as such or fermented to prepare labeled vials are then loaded into bottom tray and empty ethanol. vials are placed in the R1-R4 positions. The system is US 7,259,231 B2 11 12 checked to verify that there is enough solvent in the bottles. a pressure of 5000 psi and a temperature of 60° C. The ?ow The gas is turned on followed by the ASE. rate is 3 liters/minute. The extraction time is thirty minutes. For the examples below, the following program schedule Atotal of 0.37 g of solid yellow material is extracted (2.89% comprises three cycles of 20 minutes each with an oven of feedstock), plus an additional 0.06 g accumulated in the temperature at 140° C. A 100% methyl alcohol ?ush is used cold trap. Supercritical carbon dioxide at these processing with a 60 second purge and a 50% acetone/50% cyclohexane conditions shows high selectivity for resin. The extract rinse. The samples are then loaded and the run is started. The sample has a resin concentration in the CO2 of 37.04% and vials are placed into a freezer until ready to centrifuge. The is among the highest of all the samples submitted. However vials are shaken gently (not stirred). About 20 ml of the the yield at 2.89% of feedstock is much lower than higher sample mixture is poured or pipetted into the centrifuge tube pressure and temperature samples. The percentage of rubber and an equal amount of methyl alcohol is added. The vial is in the extract is 2.77% of the feedstock, which is a high value capped and is centrifuged at 3500 rpm for 20 minutes. for organic non-polar co-solvents. Following centrifugation, all but about 5 ml of superna Example 2 tant is poured or pipetted off into the aluminum pan. The remainder of extract is added to the tube. The vial is rinsed 50 ml Extraction with Hexane Co-Solvent (9800 with 5 ml cyclohexane, and the rinse is added to the tube. The vial is then rinsed with 5 ml acetone, and that rinse is psi, 100° C.) also added to tube. Finally, an equal amount of methyl 15.05 g of guayule shrub feedstock is placed in an alcohol is added to centrifuge tube. The tube is then capped extraction vessel and extracted with carbon dioxide and 60 and centrifuged at 3500 rpm for 20 minutes. 20 Following this centrifugation, all supernatant is poured off g of hexane co-solvent at a pressure of 9800 psi and a temperature of 100° C. The ?ow rate is 3 liters/minute. The into the pan, and the pan and the tube are left to dry in the time of extraction is twenty-three minutes. 1.21 g of dark hood. The dry pan is then placed in vacuum oven at 60° C. for 30 minutes. The pan and tube are then weighed and the green ?lm is extracted (8.04% of feedstock). An additional 1.41 g of primarily hexane is collected in the cold trap. percent resin and rubber are calculated using the following 25 Supercritical carbon dioxide at these processing conditions formulas: shows the best extraction capability for rubber when com pared to all the other previous experiments. The extract sample has a resin concentration in the CO2 Formula 1: of 16.20% and is among the lowest concentration of resin; 30 , Dried wt. of Acetone extract however, the yield at 8.04% of feedstock is higher than % Resin: — X 100 Sample wt. previous experiments. The percentage of rubber in the Formula 2: extract is 4.98% of the feedstock. These process conditions indicate that the presence of relatively low concentration of Dried wt. of Cyclohexane extract % Rubber : i X100 hexane co-solvent appears to promote the extraction of Sample wt. 35 rubber. The analysis of the residue shows that the concen tration of residual resin is 2.2% using the ASE method, and The following is a sample calculation illustrating use of the concentration of rubber in the residue is 1.8%. This the above rubber and resin formulas: example illustrates the increased rubber yield using the disclosed supercritical solvent extraction method including a 40 non-polar solvent.

A) Sample weight 1.4919 g Example 3 B) Al dish tare wt. for acetone extraction 2.2214 g C) Al dish + extracted residue 2.3304 g 50 ml Extraction with Hexane Co-Solvent (5000 D) Acetone residue wt. = (C — B) 0.1090 g 45 E) Tube tare wt. for cyclohexane extraction 11.2777 g psi, 100° C.) F) Tube + extracted residue 11.3118 g G) (Cyclo)hexane residue wt. = (F — E) 0.0341 g 15.00 g of guayule shrub feedstock is placed in an extraction vessel and extracted with carbon dioxide and 110 g of hexane co-solvent at a pressure of 5000 psi and a 50 temperature of 100° C. The ?ow rate is 3 liters/minute. The extraction is run for forty-?ve minutes. 0.71 g of dark green Formula 1: ?lm is extracted (4.73% of feedstock). An additional 14.89 ‘7 R ‘ — 01090 g>

50 ml Extraction With Hexane Co-Solvent (9800 50 ml Extraction With l-Hexene Co-Solvent (9800 psi, 102° C.) psi, 100° C.)

13.88 g of guayule shrub feedstock is placed in an 13.00 g of guayule shrub feedstock is placed in an extraction vessel and extracted With carbon dioxide and 100 extraction vessel and extracted With carbon dioxide and g of hexane co-solvent at a pressure of 9800 psi and a 114.16 g of 1-hexene co-solvent at a pressure of 9800 psi temperature of 102° C. The How rate is 3 liters/minute. The and a temperature of 100° C. The How rate is 3 liters/minute. extraction is run for ?fteen minutes. 0.71 g of dark green The extraction is run for one hour. 0.68 g of dark green ?lm ?lm is extracted (5.12% of feedstock). An additional 7.38 g is extracted (5.85% of feedstock). An additional 0.44 g of of primarily hexane is collected in the cold trap. Supercriti primarily hexene is collected in the cold trap. Supercritical cal carbon dioxide at these processing conditions shoWs very carbon dioxide at these processing conditions shoWs very good selectivity for rubber. The extract sample has a 16.81% good selectivity for rubber. The extract sample has a com concentration of resin, hoWever, the feedstock yield of bined average resin concentration of 11.4% and a 5.85% 5.12% is high. The percentage of rubber in the extract is feedstock yield. The percentage of rubber in the extract is 14.63% of the feedstock, Which is relatively high, shoWing 13.4% of the feedstock, indicating that rubber is highly that rubber is extractable at these process conditions. These extractable at these process conditions. These process con process conditions indicate that the presence of hexane ditions indicate that the presence of 1-hexene co-solvent co-solvent promotes the extraction of rubber. Using the ASE 20 promotes the extraction of rubber. Using the ASE method, method, the residue has a 2.1% concentration of resin and a the residue has a 2.0% concentration of resin and a 1.1% 1.1% concentration of rubber. concentration of rubber. Example 5 Example 8 25 50 ml Extraction With Hexane Co-Solvent (9900 psi, 800 C.) 50 ml Extraction With Cyclohexane Co-Solvent (9500 psi, 100° C.) 12.98 g of guayule shrub feedstock is placed in an extraction vessel and extracted With carbon dioxide and 11 30 13.00 g of guayule shrub feedstock is placed in an 5.38 g of hexane co-solvent at a pressure of 9900 psi and a extraction vessel and extracted With carbon dioxide and temperature of 800 C. The flow rate is 3 liters/minute. The 109.80 g of cylohexane co-solvent at a pressure of 9500 psi extraction is run for thirty minutes. 0.60 g of dark green ?lm and a temperature of 100° C. The How rate is 3 liters/minute. is extracted (4.62% of feedstock). An additional 0.26 g of The extraction is run for one hour. 0.81 g of dark green ?lm primarily hexane is collected in the cold trap. Supercritical 35 is extracted (6.23% of feedstock). An additional 0.40 g of carbon dioxide at these processing conditions shoWs very primarily cyclohexane is collected in the cold trap. Super good selectivity for rubber. The extract sample has a 12.35% critical carbon dioxide at these processing conditions shoWs concentration of resin and a 4.62% yield of feedstock. The very good selectivity for resin. The extract sample has a percentage of rubber in the extract is 8.97% of the feedstock combined average resin concentration of 30.1% and a 6.23% and indicates that rubber is extractable at these process 40 yield of feedstock. The percentage of rubber in the extract is conditions. These process conditions further indicate that the 7.8% of the feedstock, indicating that both resin and rubber presence of hexane co-solvent promotes the extraction of are extractable at these process conditions. Using the ASE rubber. Using the ASE method, the residue has a 2.3% method, the residue has a 3.0% concentration of resin and a concentration of resin and a 1.1% concentration of rubber. 3.9% concentration of rubber. 45 Example 6 Example 9

50 ml Extraction With Hexane Co-Solvent (9800 50 ml Extraction With lso-Octane Co-Solvent (9500 psi, 80° C.) psi, 100° C.) 50 13.10 g of guayule shrub feedstock is placed in an 13.00 g of guayule shrub feedstock is placed in an extraction vessel and extracted With carbon dioxide and extraction vessel and extracted With carbon dioxide and 110.16 g of hexane co-solvent at a pressure of 9800 psi and 110.26 g of iso-octane co-solvent at a pressure of 9500 psi a temperature of 80° C. The How rate is 3 liters/minute. The and a temperature of 100° C. The How rate is 3 liters/minute. extraction is run for one hour. 1.47 g of dark green ?lm is 55 The extraction is run for one hour. 0.71 of dark green ?lm extracted (11.22% of feedstock). An additional 0.14 g of is extracted (5.46% of feedstock). An additional 0.17 g of primarily hexane is collected in the cold trap. Supercritical primarily iso-octane is collected in the cold trap. Supercriti carbon dioxide at these processing conditions shoWs very cal carbon dioxide at these processing conditions shoWs good selectivity for rubber. The extract sample has a com good selectivity for resin. The extract sample of >30.1% bined average resin concentration of slightly less than 10% 60 resin is high, as is the total yield of feedstock at 5.46%. The and an 11.22% yield of feedstock. The percentage of rubber percentage of rubber in the extract is 3.9% of the feedstock, in the extract is 10.5% of the feedstock, indicating that Which Was moderate compared to most other organic non rubber is highly extractable at these process conditions. polar co-solvent experiments, indicating that iso-octane is These process conditions indicate that the presence of hex not as ef?cacious a co-solvent for extracting rubber as ane co-solvent appears to promote the extraction of rubber. 65 hexane, 1-hexene, or cyclohexane. Using the ASE method, Using the ASE method, the residue has a 2.0% concentration the residue has a 2.5% concentration of resin and a 4.5% of resin and a 0.8% concentration of rubber. concentration of rubber. US 7,259,231 B2 1 5 16 Example 10 achieve How and no extract is collected. The guayule feedstock, at least at the particle siZe at Which the test Was 50 ml Extraction With Water Co-Solvent, (9800 psi, performed, does not have an adequate percolation rate to 100° C.) perform the extraction. The sloW percolation rate of the liquid carbon dioxide causes the bed to compress and form 14.72 g of guayule shrub feedstock is placed in an a plug, Which prevents extraction. Liquid carbon dioxide extraction vessel and extracted With carbon dioxide and 7.32 requires the use of a specialiZed extractor, pelletiZing of the g of Water co-solvent at a pressure of 9800 psi and a feedstock, or a much larger particle siZe, in order for this temperature of 1000 C. The How rate is 3 liters/minute. The liquid carbon dioxide process to Work effectively. time of extraction is thirty minutes. 0.59 g of primarily solid Example 13 yellow material is extracted (4.00% of feedstock), and an additional 0.16 g is collected in the cold trap. Supercritical 50 ml Extraction With Ethanol Co-Solvent, (7250 carbon dioxide at these processing conditions shoWs high psi, 800 C.) selectivity for resins. The extract sample has a 39.59% concentration of resin, indicating that Water promotes the 15.04 g of-guayule shrub feedstock is placed in an extrac extraction of resin, and a yield of 4.00% of feedstock. tion vessel and extracted With carbon dioxide and 15 g of HoWever, the percentage of rubber in the extract is only ethanol co-solvent at a pressure of 7250 psi and a tempera 0.83% of the feedstock. These process conditions shoW a ture of 800 C. The How rate is 3 liters/minute. The time of very high selectivity for resin and a relatively loW selectivity extraction is 45 minutes. 0.58 g of solid yelloW material and for rubber, indicating the presence of Water promotes the 20 dark green ?lm is extracted (3.85% of feedstock). Super extraction of resin and depresses the extraction of rubber. critical carbon dioxide at these processing conditions shoWs These process conditions are suitable for a tWo-step com average selectivity for resins. The extract sample at 30.09% mercial process that selectively extracts resin and leaves concentration of resin is not as high as other experiments. behind the rubber for subsequent extract. The material in the The yield at 3.85% of feedstock is not as high as other cold trap is much loWer in resin and rubber concentration 25 process conditions utiliZing higher pressure or Water and than in the collection vessel. Using the ASE method, the other co-solvents. residue has a 2.3% concentration of resin, and a 5.7% HoWever, the percentage of rubber in the extract is concentration of rubber. reported at 0.51% of the feedstock, Which is extremely loW, indicating that the presence of ethanol suppresses the extrac tion of rubber. These process conditions are suboptimal for 30 Example 11 a process designed to extract both resin and rubber, but the presence of ethanol may be bene?cial for a single step 50 ml Extraction With Water Co-Solvent, (5000 psi, process to extract a puri?ed resin product. Using the ASE 60° c.) method, the residue has a 2.6% concentration of resin, and a 5.4% concentration of rubber. 16.26 g of guayule shrub feedstock is placed in an 35 extraction vessel and extracted With carbon dioxide and 8.07 Example 14 g of Water co-solvent at a pressure of 5000 psi and a temperature of 600 C. The How rate is 3 liters/minute. The 50 ml Extraction With Acetone Co-Solvent, (5000 time of extraction is 24 minutes. 0.68 g of primarily solid psi, 600 C.) yelloW material is extracted (4.18% of feedstock), and an 40 additional 0.13 g is collected in the cold trap. The extract 15.06 g of guayule shrub feedstock is placed in an sample at 28.8% concentration of resin is not nearly as high extraction vessel and extracted With carbon dioxide and 15 as the previous experiment Which is performed at a higher g of acetone co-solvent at a pressure of 5000 psi and a pressure and temperature. The yield at 4.18% of feedstock is temperature of 600 C. The How rate is 3 liters/minute. The among the highest. 45 time of extraction is 45 minutes. 0.63 g of dark green ?lm HoWever, the percentage of rubber in the extract is is extracted (4.18% of feedstock). Supercritical carbon diox reported at only 0.37% of the feedstock Which is among the ide at these processing conditions shoWed extraordinary selectivity for resins. The extract sample at 40.02% concen loWest amount When compared to other process conditions. tration of resin is the highest of all the experiments. The These process conditions shoW that the presence of Water yield at 4.81% of feedstock is among the highest Within this suppresses the extraction of the rubber, but that the higher 50 set of screening experiments. The percentage of rubber in pressure conditions are more conducive for the extraction of the extract is reported at 1.72% of the feedstock but is resin. The material in the cold trap has extremely loW surpassed by several other experiments. concentrations of resin and rubber compared to that in the These process conditions indicate that the presence of collection vessel. Using the ASE method, the residue had a acetone promotes the extraction of resin. These process 2.6% concentration of resin, and a 5.8% concentration of 55 conditions should be considered as a single step in a tWo rubber. step process for extracting resin and rubber separately and sequentially. Using the ASE method, the residue has a 2.9% Example 12 concentration of resin, and a 6.5% concentration of rubber.

50 ml Liquid Carbon Dioxide Extraction, (2000 60 Example 15 psi, 9.20 C.) 50 ml Extraction With Hexane Co-Solvent, (5000 16.1 g of guayule shrub feedstock is placed in an extrac psi, 600 C.) tion vessel and extracted With carbon dioxide at a pressure of 2000 psi and a temperature of 9.20 C. The extract vessel 65 16.12 g of guayule shrub feedstock is placed in an and pre-heater vessel are both placed in a container With ice extraction vessel and extracted With carbon dioxide and 15 to perform a cold extraction, hoWever, We are unable to g of hexane co-solvent at a pressure of 5000 psi and a US 7,259,231 B2 17 18 temperature of 60° C. The How rate is 3 liters/minute. The 2. The method of claim 1, Wherein the solvent is carbon time of extraction is forty-?ve minutes. 0.53 g of solid dioxide. yellow material and dark green ?lm is extracted (3.28% of 3. The method of claim 2, further including contacting the feedstock). Supercritical carbon dioxide at these processing plant material With a co-solvent. conditions shoWs very good selectivity for resins. The 4. The method of claim 3, Wherein the co-solvent is a extract sample at 34.69% concentration of resin is among the polar co-solvent. highest of the experiments; hoWever, the yield at 3.28% of 5. The method of claim 3, Wherein the co-solvent is a feedstock is not as high as several other experiments. non-polar co-solvent. The percentage of rubber in the extract is reported at 6. The method of claim 3, Wherein the step of contacting 1.09% of the feedstock, Which is relatively loW, shoWing the With the solvent and the step of contacting With the co rubber is still not extracted in great quantity, utiliZing these solvent are performed either sequentially or in reverse order. particular process conditions. These process conditions indi 7. The method of claim 3, Wherein the step of contacting cate that the presence of relatively loW concentration of With the solvent and the step of contacting With the co hexane co-solvent appears to promote the extraction of resin solvent are performed at approximately the same time. and slightly promote the extraction of rubber. These process 8. The method of claim 1, Wherein the pressure is betWeen conditions should be considered as a single step in a tWo about 5,000 and 10,000 psi. step process for extracting resin and rubber separately and 9. The method of claim 1, Wherein the temperature is sequentially. Using the ASE method, the residue has a 2.9% betWeen 60 and 100 degrees centigrade. concentration of resin and a 5.3% concentration of rubber. 10. The method of claim 1, further comprising contacting Therefore, the present method of using supercritical car 20 the plant material With a co-solvent. bon dioxide eliminates or greatly decreases the use of 11. The method of claim 10, Wherein the co-solvent is a organic solvents Which are oZone depleting and environ polar co-solvent. mentally unfriendly, While providing a more effective 12. The method of claim 10, Wherein the co-solvent is a method of separating, fractionating and purifying rubber and non-polar co-solvent. resins from plant materials. 25 13. The method of claim 10, Wherein the step of contact Various embodiments of the invention are described ing With the compressed gas solvent and the step of con above in the Detailed Description. While these descriptions tacting With the co-solvent are performed either sequentially directly describe the above embodiments, it is understood or in reverse order. that those skilled in the art may conceive modi?cations 14. The method of claim 10, Wherein the step of contact and/or variations to the speci?c embodiments shoWn and 30 ing With the compressed gas solvent and the step of con described herein. Any such modi?cations or variations that tacting With the co-solvent are performed at approximately fall Within the purview of this description are intended to be the same time. included therein as Well. Unless speci?cally noted, it is the 15. The method of claim 1, further comprising extracting intention of the inventor that the Words and phrases in the a resin from the plant material to form a non-resin biopoly speci?cation and claims be given the ordinary and accus 35 mer and resin extraction. tomed meanings to those of ordinary skill in the applicable 16. The method of claim 15, further comprising fraction art(s). ating the nonresin biopolymer and resin extraction into a The foregoing description of a preferred embodiment and non-resin biopolymer fraction and a resin fraction. best mode of the invention knoWn to the applicant at this 17. A method for removing a non-resin biopolymer from time of ?ling the application has been presented and is 40 intended for the purposes of illustration and description. It is plant material, comprising: not intended to be exhaustive or limit the invention to the contacting plant material With a compressed gas solvent precise form disclosed and many modi?cations and varia compressed from about 1,500 psi to about 10,000 psi, tions are possible in the light of the above teachings. The Wherein the temperature and pressure of the solvent are at supercritical conditions; embodiment Was chosen and described in order to best 45 explain the principles of the invention and its practical maintaining the supercritical conditions for a suf?cient application and to enable others skilled in the art to best time, Wherein the biopolymer solubiliZes With the sol utiliZe the invention in various embodiments and With vent forming a supercritical solution; and various modi?cations as are suited to the particular use extracting the biopolymer by percolation of the super critical solution through a bed of the plant material and contemplated. Therefore, it is intended that the invention not 50 be limited to the particular embodiments disclosed for Wherein the biopolymer is rubber. carrying out this invention, but that the invention Will 18. The method of claim 17, Wherein the solvent is carbon include all embodiments falling Within the scope of the dioxide. appended claims. 19. The method of claim 17, Wherein the pressure is What is claimed is: 55 betWeen about 5,000 and 10,000 psi. 1. A method for removing a non-resin biopolymer from 20. The method of claim 17, Wherein the temperature is plant material, comprising: betWeen 60 and 100 degrees centigrade. contacting plant material With a compressed gas solvent 21. The method of claim 17, further including extracting compressed from about 1,500 psi to about 10,000 psi, a resin from the plant material to form a non-resin biopoly Wherein the temperature and pressure of the solvent are 60 mer and resin extraction. at supercritical conditions; 22. The method of claim 21, further comprising fraction maintaining the supercritical conditions for a suf?cient ating the non-resin biopolymer and resin extraction into a time, Wherein the biopolymer solubiliZes With the sol biopolymer fraction and a resin fraction. vent forming a supercritical solution; and 23. A method for removing a biopolymer from plant extracting the biopolymer by percolation of the super 65 material, comprising: critical solution through a bed of the plant material and contacting plant material With a compressed gas solvent Wherein the plant material is guayule. compressed from about 1,500 psi to about 10,000 psi, US 7,259,231 B2 19 20 wherein the temperature and pressure of the solvent are 31. The method of claim 28, Wherein the solvent is carbon at subcritical liquid conditions; dioxide. maintaining the subcritical liquid conditions for a suffi 32. The method of claim 28, Wherein the solvent is Water. cient time, Wherein the biopolymer and the solvent 33. A method for removing a non-polar rubber and a polar form a subcritical liquid solvent solution; and 5 resin from guayule, comprising: extracting the biopolymer by percolation of the subcritical contacting guayule With carbon dioxide in an extraction liquid solvent solution through a bed of the plant vessel, Wherein the temperature in the extraction vessel material and Wherein the plant material is guayule. is betWeen 60 and 100 degrees centigrade and the 24. The method of claim 23, further comprising using an pressure in the extraction vessel is betWeen 5,000 and inert percolation aid. 10,000 psi; 25. The method of claim 24, Wherein the percolation aid further contacting the guayule With a co-solvent in the is diatomaceous earth. extraction vessel, Wherein the contact With the co 26. The method of claim 23, Wherein the solvent is carbon solvent occurs at approximately the same time as the dioxide. contact With the carbon dioxide; and 27. The method of claim 23, Wherein the solvent is Water. extracting the rubber and resin by percolation of a formed 28. A method for removing a biopolymer from plant supercritical solution through a bed of guayule, to form material, comprising: a rubber-resin extraction. contacting plant material With a compressed gas solvent 34. The method of claim 33, Wherein the co-solvent is a compressed from about 1,500 psi to about 10,000 psi, non-polar solvent. Wherein the temperature and pressure of the solvent are 20 at subcritical liquid conditions; 35. The method of claim 34, further comprising a third maintaining the subcritical liquid conditions for a suffi solvent, Wherein the third solvent is a polar solvent. cient time, Wherein the biopolymer and the solvent 36. The method of claim 33, Wherein the co-solvent is a form a subcritical liquid solvent solution; and polar solvent. extracting the biopolymer by percolation of the subcritical 25 37. The method of claim 33, further comprising fraction liquid solvent solution through a bed of the plant ating the rubber-resin extraction into a rubber fraction and a material and Wherein the biopolymer is rubber. resin fraction. 29. The method of claim 28, further comprising using an 38. The method of claim 33, Wherein the co-solvent ratio inert percolation aid. is betWeen 3 to 10 times a pre-determined feedstock Weight. 30. The method of claim 29, Wherein the percolation aid 30 is diatomaceous earth. * * * * *