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WO1990005621A1 - Procede servant a introduire par perfusion dans une piece a usiner poreuse une preparation chimique au moyen de cosolvants - Google Patents

Procede servant a introduire par perfusion dans une piece a usiner poreuse une preparation chimique au moyen de cosolvants Download PDF

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Publication number
WO1990005621A1
WO1990005621A1 PCT/US1989/005050 US8905050W WO9005621A1 WO 1990005621 A1 WO1990005621 A1 WO 1990005621A1 US 8905050 W US8905050 W US 8905050W WO 9005621 A1 WO9005621 A1 WO 9005621A1
Authority
WO
WIPO (PCT)
Prior art keywords
chemical composition
chemical
supercritical
fluid
cosolvent
Prior art date
Application number
PCT/US1989/005050
Other languages
English (en)
Inventor
Ferhan Kayihan
Aydin K. Sunol
Original Assignee
Weyerhaeuser Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Weyerhaeuser Company filed Critical Weyerhaeuser Company
Publication of WO1990005621A1 publication Critical patent/WO1990005621A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
    • C04B41/4505—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements characterised by the method of application
    • C04B41/4535—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements characterised by the method of application applied as a solution, emulsion, dispersion or suspension
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D1/00—Processes for applying liquids or other fluent materials
    • B05D1/18—Processes for applying liquids or other fluent materials performed by dipping
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
    • B05D7/06—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials to wood
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D2401/00—Form of the coating product, e.g. solution, water dispersion, powders or the like
    • B05D2401/90—Form of the coating product, e.g. solution, water dispersion, powders or the like at least one component of the composition being in supercritical state or close to supercritical state
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27K—PROCESSES, APPARATUS OR SELECTION OF SUBSTANCES FOR IMPREGNATING, STAINING, DYEING, BLEACHING OF WOOD OR SIMILAR MATERIALS, OR TREATING OF WOOD OR SIMILAR MATERIALS WITH PERMEANT LIQUIDS, NOT OTHERWISE PROVIDED FOR; CHEMICAL OR PHYSICAL TREATMENT OF CORK, CANE, REED, STRAW OR SIMILAR MATERIALS
    • B27K3/00—Impregnating wood, e.g. impregnation pretreatment, for example puncturing; Wood impregnation aids not directly involved in the impregnation process
    • B27K3/02—Processes; Apparatus
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27K—PROCESSES, APPARATUS OR SELECTION OF SUBSTANCES FOR IMPREGNATING, STAINING, DYEING, BLEACHING OF WOOD OR SIMILAR MATERIALS, OR TREATING OF WOOD OR SIMILAR MATERIALS WITH PERMEANT LIQUIDS, NOT OTHERWISE PROVIDED FOR; CHEMICAL OR PHYSICAL TREATMENT OF CORK, CANE, REED, STRAW OR SIMILAR MATERIALS
    • B27K3/00—Impregnating wood, e.g. impregnation pretreatment, for example puncturing; Wood impregnation aids not directly involved in the impregnation process
    • B27K3/02—Processes; Apparatus
    • B27K3/0278—Processes; Apparatus involving an additional treatment during or after impregnation
    • B27K3/0285—Processes; Apparatus involving an additional treatment during or after impregnation for improving the penetration of the impregnating fluid

Definitions

  • the present invention is a method of enhancing the perfusion of a porous workpiece with a chemical composition using two or more given fluid solvents under supercritical conditions.
  • the method is particularly well adapted for impregnation and deposition into wood of preservative and other materials which have poor solubility in supercritical carbon dioxide.
  • the critical temperature of a fluid is the temperature above which liquefaction is not possible at any pressure.
  • Critical pressure is defined as the pressure required to liquefy a gas at the critical temperature.
  • fluids are said to be under supercritical conditions. While not truly liquids, they maintain many of the properties of a liquid. However, there are also significant differences.
  • the solvent power of supercritical fluids for various materials is increased significantly above the critical point. When a chemical material is dissolved in a supercritical fluid, the resulting solution appears to have most or all of the characteristics of a true solution. However, the viscosities of these supercritical solutions are very much lower than viscosities of conventional solutions.
  • West German Offenlegungsschrift 28 53 066 describes the use of supercritical solutions to coat the surface of porous powders or porous articles, such as active nickel catalysts, with an inert protective material. Conditions are regulated so that coatings only a few molecules thick can be applied to the material. In addition to the protection of the active catalysts, the inventors disclose that other porous materials, such as fabrics, can be coated or impregnated with protective or decorative layers. The inventor further notes that by proper selection of extraction and extraction pressure and temperature, the components to be dissolved by the supercritical fluid can be dissolved selectively. Unfortunately, the inventors offer no examples or other data which is specifically informative as to how their process is carried out.
  • Japanese Kokai SHO 59[1984]-101311 discloses a preservative treatment for wood. This uses either carbon dioxide in the supercritical range or liquid carbon dioxide near the supercritical range as a solvent for the preservative.
  • the inventors claim the advantages of faster permeation of the preservative into the wood, elimination of the need of predrying treatment or incising and, above all, the elimination of the need for waste treatment of residual preservative chemical solutions.
  • the one example in the patent shows the use of a water soluble phenol-group inorganic fluoride wood preservative agent in liquid carbon dioxide to treat beech wood.
  • the composition of the treating material is not further described nor is it made clear whether or not any water was present.
  • the carbon dioxide was approximately 11°C below the critical temperature at which point it would be a true liquid.
  • the preservative agent had permeated to the center of a cube of wood 10 cm on each side. This would not be surprising even under conventional treating conditions due to the short specimen length and large exposed area of end grain. Liquids are well known to permeate end grain at a rate 10-20 times faster than the rate across the grain. However, if the treatment would work as described for larger specimens, it could potentially be very useful.
  • the present invention is a method of perfusing a porous workpiece, such as wood, with a chemical composition that is generally insoluble in a first fluid under conditions near or above the critical point.
  • the method comprises providing a cosolvent in which the chemical composition has at least limited solubility when the mixture of first fluid and cosolvent is raised to supercritical conditions.
  • the cosolvent may be either a pure chemical compound or a mixture of chemical compounds.
  • the chemical composition is then dissolved by contacting it with a mixture of the first fluid and a sufficient amount of the cosolvent. This contact must occur under conditions near or above the critical point for a sufficient time to solubilize at least a portion of the chemical composition. This forms a supercritical solution of the chemical composition.
  • the process then involves contacting and impregnating the porous substrate with the supercritical solution so as to introduce the chemical material into the workpiece.
  • the workpiece is then removed from the supercritical solution; e.g., by reducing the pressure to atmospheric, so as to leave some portion of the chemical material deposited within the porous substrate of the workpiece.
  • the process is carried out under true supercritical conditions; i.e., at a temperature and pressure above those at the critical point of the first fluid.
  • the method will operate in a wholly satisfactory manner near to but somewhat below critical conditions.
  • the term "near to but somewhat below” is bounded as hereinafter described.
  • Reduced pressure P r is defined as P/P , where P is the actual pressure of the system and P c is the critical pressure.
  • Reduced temperature T is similarly defined as T/T where T is the actual operating temperature and T c is the critical temperature.
  • the invention should be considered to be in an operable range when T r and P r are each greater than 0.85.
  • the term "supercritical" should be construed sufficiently broadly to encompass the above-defined ranges.
  • the first solvent will normally be gaseous under ambient conditions although it may also be a liquid. Carbon dioxide is a preferred material for use as the first solvent.
  • the cosolvent may be any which when combined with the first solvent, and the mixture is raised to supercritical conditions, will dissolve at least 0.01 mg of the chemical composition per gram of mixed solvent. Preferably the mixture will dissolve at least 0.1 mg and more preferably at least 1 mg of the chemical composition per gram of mixed solvent. While the chemical composition will frequently have the above or greater solubility in the cosolvent alone, this is not required or necessary. The criterion for solubility is determined when the mixed solvent system is at supercritical conditions.
  • first dissolve the chemical composition in the cosolvent it is permissible to first dissolve the chemical composition in the cosolvent, if it has adequate solubility and then add the first fluid before or after the system is raised to supercritical conditions.
  • first fluid and cosolvent may be mixed prior to dissolving the chemical composition.
  • the cosolvent may be either aqueous or nonaqueous, and polar or nonpolar. It is assumed that the cosolvent will be miscible with the first fluid at least to the extent that a sufficient amount of the chemical composition can be dissolved in the mixture when at supercritical conditions.
  • Wood is a preferred example of a porous material that can be impregnated with a chemical composition. Chemical materials such as dyes, preservatives, those that give dimensional stability, etc., are among the many useful materials which can be impregnated within the wood.
  • a number of chemical materials are suitable for use as the primary supercritical fluid. As noted, carbon dioxide is preferred but others such as propane, nitrous oxide, saturated and unsaturated halogenated hydrocarbons containing up to about 3 carbon atoms, and mixtures of these materials are suitable. This list of fluids should be considered as exemplary and not limiting.
  • the single figure is a generalized block diagram showing a suitable process and equipment for treatment of a porous workpiece with a chemical material under supercritical conditions.
  • the equipment used for chemical treatment of various substrate materials under supercritical conditions has been generally described in the references discussed earlier.
  • the Figure shows an adaptation of this equipment for use with the present invention. While it is configured for use with laboratory scale equipment, it could readily and easily be modified for a commercial operation.
  • the equipment shown is designed to carry out two separate unit operations. The first is solubilization of the treatment chemical using a supercritical fluid solvent and suitable cosolvent. The second step is the treatment and impregnation of the porous workpiece with the dissolved chemical material while the system is still held under supercritical conditions.
  • wood will be used as an example of a porous workpiece. However, it will be understood by those skilled in the art that many other porous materials could be treated and impregnated using the process of the present invention.
  • the treatment chemical is first charged to a vessel where it is to be dissolved.
  • This will typically be a piece of process equipment, such as a packed tower, which provides a sufficient surface area for contacting the treatment chemical with a supercritical solvent and cosolvent.
  • the treatment chemical may be first dissolved in the cosolvent before It is charged to the extraction unit.
  • a supercritical fluid such as carbon dioxide or propane, is brought to an appropriate pressure before it is charged to the extraction unit.
  • the cosolvent is similarly brought to operating pressure.
  • the compressed components may first be directed through a heat exchanger to adjust the temperature to the desired operating condition. In the dissolver at least a portion of the treatment chemical is solubilized in the combined supercritical fluid and cosolvent.
  • the resulting solution is then directed to a treatment chamber where the wood is contained.
  • a treatment chamber where the wood is contained.
  • two or more treatment chambers would be employed in parallel so that one could be emptied and recharged while treatment was being carried out in an adjacent unit.
  • the treatment fluid while still under supercritical conditions, may be recycled from the treatment chamber to the dissolving unit and continuously circulated to maintain an appropriate concentration of treating chemicals.
  • an ultraviolet spectrograph is located immediately downstream from the treatment unit. This enables continuous monitoring of the concentration of dissolved material in the supercritical solution. Following this is a pressure reduction valve where the excess fluid with any remaining treatment chemical is flashed to atmospheric pressure. The low pressure fluid may then be directed through a separator where any residual treatment chemical is recovered. The residual first fluid, which usually contains some cosolvent, is either vented to atmosphere or to a recovery system where it can be reused.
  • Carbon dioxide has many characteristics which make it an almost ideal fluid for supercritical treatments. It is inexpensive, nontoxic, and is not an environmental pollutant. Unfortunately, as noted above, many desirable chemical impregnants are almost totally insoluble in supercritical carbon dioxide. However, if a suitable cosolvent is used, a sufficient amount of the treatment chemical can be brought into supercritical solution so that an adequate amount can be impregnated into the wood or other porous material.
  • Example 1 As a model porous material, four grams of glass wool was packed into a stainless steel tube 200 mm in length, 9.5 mm outside diameter and about 5 mm inside diameter. This tube was located in the apparatus in the position shown as the "treatment unit" in the drawing. As a model treating chemical a nonionic dye, C.I. Solvent Blue 35 (Color Index 61554), was chosen. This is available in 98% purity from Aldrich Chemical Company, Milwaukee, Wisconsin, as well as from other suppliers. Several grams of the dye in powder form were packed into a tube similar to that just described and retained by using a plug of glass wool in each end of the tube.
  • C.I. Solvent Blue 35 Color Index 61554
  • the overall equipment was a modified Milton Roy Supercritical Extraction Unit. This equipment is available from LDC Milton Roy, Inc., Riviera Beach, Florida. Carbon dioxide at 10350 kPa and 40°C was directed through the dissolving unit at a rate of 415 g/hr. The resultant solution from the dissolving unit was then directed through the packed glass fiber column. After a treatment time of 30 minutes, pressure in the system was reduced to atmospheric level. Prior to this time ultraviolet spectroscopy of the supercritical fluid stream indicated a solubility of the solvent blue dye of only 0.021 mg/g (.0021%) of carbon dioxide. After removal of the glass fiber packed treatment cell, the glass fiber was extracted with acetone to measure the amount of dye transferred. Replicate runs averaged 0.059 mg of Solvent Blue dye per gram of glass fiber (0.0059%).

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Wood Science & Technology (AREA)
  • Dispersion Chemistry (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Chemical And Physical Treatments For Wood And The Like (AREA)

Abstract

Le procédé décrit sert à introduire par perfusion dans un matériau tel que du bois une préparation chimique qui est insoluble dans un premier fluide donné dans des conditions surcritiques. Un cosolvant est mélangé au premier solvant pour conférer à la préparation chimique la solubilité adéquate aux conditions surcritiques. Un tel procédé est utilisé pour imprégner uniformément des matériaux autrement difficilement perméables. L'imprégnation de bois d'÷uvre ou de bois de charpente avec un agent conservateur est une application type de la présente invention.
PCT/US1989/005050 1988-11-14 1989-11-14 Procede servant a introduire par perfusion dans une piece a usiner poreuse une preparation chimique au moyen de cosolvants WO1990005621A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US27018588A 1988-11-14 1988-11-14
US270,185 1988-11-14

Publications (1)

Publication Number Publication Date
WO1990005621A1 true WO1990005621A1 (fr) 1990-05-31

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PCT/US1989/005050 WO1990005621A1 (fr) 1988-11-14 1989-11-14 Procede servant a introduire par perfusion dans une piece a usiner poreuse une preparation chimique au moyen de cosolvants

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4202320A1 (de) * 1992-01-29 1993-08-05 Dierk Dr Knittel Verfahren zum impraegnieren von substraten
EP0912461A4 (fr) * 1996-05-20 1999-10-27 Materials Technology Ltd Traitement de ciment hydraulique, ceramique ou grave-ciment durcis au moyen de fluides haute pression
WO2006092673A1 (fr) * 2004-09-30 2006-09-08 The State Of Queensland Acting Through The Department Of Primary Industries And Fisheries Dispositif d'impregnation et procede
AU2005328560B2 (en) * 2004-09-30 2011-09-01 Carter Holt Harvey Wood Products Australia Pty Limited Impregnation apparatus and method

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4552786A (en) * 1984-10-09 1985-11-12 The Babcock & Wilcox Company Method for densification of ceramic materials

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4552786A (en) * 1984-10-09 1985-11-12 The Babcock & Wilcox Company Method for densification of ceramic materials

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
CHEMICAL ABSTRACTS, Vol. 102, No. 2, 14 January 1985, (Colombus, Ohio, US), see page 101* Abstract No. 8473b & JP-A-59101311 (Japan Oxygen Co. Ltd) 11 June 1984* *
CHEMICAL ABSTRACTS, Vol. 109, No. 4, 25 July 1988, (Columbus, Ohio, US), L. LI et al.: "Interaction of Supercritical Fluids with Lignocellulosic Materials", see page 68* Abstracht No. 24357s & Ind. Eng. Chem. Res. 1988, 27/7) 1301-12 * *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4202320A1 (de) * 1992-01-29 1993-08-05 Dierk Dr Knittel Verfahren zum impraegnieren von substraten
EP0912461A4 (fr) * 1996-05-20 1999-10-27 Materials Technology Ltd Traitement de ciment hydraulique, ceramique ou grave-ciment durcis au moyen de fluides haute pression
WO2006092673A1 (fr) * 2004-09-30 2006-09-08 The State Of Queensland Acting Through The Department Of Primary Industries And Fisheries Dispositif d'impregnation et procede
AU2005328560B2 (en) * 2004-09-30 2011-09-01 Carter Holt Harvey Wood Products Australia Pty Limited Impregnation apparatus and method

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