US3460979A - Process of impregnating capillary materials such as wood,under pressure in a closed vessel - Google Patents

Process of impregnating capillary materials such as wood,under pressure in a closed vessel Download PDF

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Publication number
US3460979A
US3460979A US542176A US3460979DA US3460979A US 3460979 A US3460979 A US 3460979A US 542176 A US542176 A US 542176A US 3460979D A US3460979D A US 3460979DA US 3460979 A US3460979 A US 3460979A
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United States
Prior art keywords
pressure
liquid
wood
impregnating
filament
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Expired - Lifetime
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US542176A
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English (en)
Inventor
Ernest Giese
Egon Schubert
Konrad Rienesl
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GUIDO RUTGERS
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GUIDO RUTGERS
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Classifications

    • 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
    • B27K3/08—Impregnating by pressure, e.g. vacuum impregnation
    • 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
    • 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
    • B27K3/34—Organic impregnating agents
    • B27K3/44—Tar; Mineral oil
    • B27K3/48—Mineral oil
    • 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
    • B27K5/00—Treating of wood not provided for in groups B27K1/00, B27K3/00
    • B27K5/001—Heating
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/4935—Impregnated naturally solid product [e.g., leather, stone, etc.]
    • Y10T428/662—Wood timber product [e.g., piling, post, veneer, etc.]

Definitions

  • This invention relates to a process of impregnating capillary materials, such as wood, under pressure in a closed vessel.
  • the invention relates particularly to the impregnation of materials which cannot be impregnated economically or cannot be impregnated at all by known methods.
  • a known process involves the application of vacuum and pressure.
  • a previous vacuum or a liquid pressure is utilized to produce a pressure gradient between the surface and the interior of the material to be impregnated, so that the liquid penetrates into the interior in the form of capillary filaments.
  • the length of the filament increases and the pressure gradient drops.
  • the rate of liquid penetration decreases progressively so that a complete impregnation takes a long time.
  • FIG. 1 of the accompanying drawing represents a general case.
  • a liquid filament F has entered a capillary K which extends from the surface 0 of the material.
  • the filament is at the surface 0 under the superatmospheric pressure p and at its tip 1 is under atmospheric pressure at the time of observation.
  • Curve 3 represents the pressure gradient.
  • a material to be impregnated such as wood
  • the penetration of the filament ceases when the pressure of the filament is no longer sutficient to overcome this resistance.
  • FIG. 2 Such a case is shown in FIG. 2.
  • FIG. 2 shows a capillary K which extends from the surface 0 and is interrupted by perforated transverse walls Q Q Q etc.
  • a pressure gradient as represented by curve 5.
  • Pressure losses W W W etc. will be caused by the resistances at the transverse walls Q Q Q
  • the losses due to friction may be neglected.
  • the flow virtually ceases when the superatmospheric pressure 12 has been consumed by the resistances to the flow, particularly by the resistances which are due to the trans-i verse walls Q to Q
  • the stepped pressure-gradient curve 5 includes generally an angle (or slope) a relative to the horizontal.
  • the penetration of the impregnating agent having a high viscosity can be promoted by an addition of solvents to impregnating agents or by heating the impregnating agents. These measures reduce the viscosity of the impregnating agent. Owing to their low viscosity, gases and vapors can easily be introduced and can be deposited inside the capillaries. These processes, however, do not involve a change of the pressure in the liquid filament.
  • the process according to the invention is characterized in that vapor is produced in the proceeding liquid filament while the impregnating liquid is being forced into the material to be impregnated, said production of vapor being effected with the aid of a highly volatile substance and by heating and the vapor being produced in such an amount that the pressure in the liquid filament is increased to a value which does not exceed the external pressure, or a gas is produced with the aid of a substance which evolves a gas together with the impregnating liquid and in such an amount that the pressure in the liquid filament is increased to a value which does not exceed the external pressure.
  • the increase of pressure which has been described for the region between the transverse walls Q and Q, is obtained throughout the material to be impregnated in any section of the liquid filaments between two transverse walls. It begins on the outside and proceeds inwardly and is effected, e.g., by a transformation of a liquid into vapor by heating, or by an evolution of gas in a chemical reaction. This may result in an increase of the pressure in the capillary, e.g., at Q, in FIG. 2, to the value of the external pressure.
  • a low-boiling substance is dissolved in the impregnating liquid, e.g., methylene chloride in tar oil, or carbon dioxide in an aqueous solution, the capillary substance is subjected to the pressure of this impregnating liquid, and the impregnating liquid is heated so that the pressure in the liquid filament is in- O creased to a value not exceeding the external pressure, while the superatmospheric external pressure is maintained.
  • the impregnating liquid e.g., methylene chloride in tar oil, or carbon dioxide in an aqueous solution
  • a low-boiling substance such as methyelne chloride vapor or carbon dioxide
  • methyelne chloride vapor or carbon dioxide is introduced into the capillaries so that the methylene chloride is condensed and the carbon dioxide is dissolved in the water contained in the capillary material, whereafter the impregnating liquid is introduced under pressure and is subsequently heated while the external superatmospheric pressure is maintained, whereby the pressure in the liquid filament is increased to a value which is not in excess of the external pressure.
  • German patent specification No. 138,933 discloses a process in which the material to be impregnated is subjected to a high air or gas pressure before it is treated with the impregnating liquid and this air or gas pressure is maintained or even increased during the subsequent treatment with the impregnating liquid.
  • the process according to the invention differs from this known process in that a vapor which has been introduced into the material to be impregnated must condense or a gas which has been introduced must be dissolved in the water contained in the capillary substance, the vapor or gas pressure need not be maintained during the subsequent treatment with the impregnating liquid, when such vapor or gas pressure would even have an obstructing effect, and the impregnating liquid must be heated in order to activate the condensed vapor or the dissolved gas so that the vapor or gas can become effective to increase the pressure of the liquid filament. As the temperature rise proceeds inwardly, the pressure in the filament is continually increased close to the tip of the filament. In the abovementioned process of the Wassermann patent, the
  • Capillary materials tend to absorb or discharge moisture in response to a temperature change and for this reason always contain moisture.
  • the impregnating liquid and an auxiliary liquid are separately introduced into the capillaries of the material, and said two liquids react to evolve a gas so that an increase of pressure in the capillaries is obtained while the superatmospheric external pressure is maintained.
  • This increase of pressure may be assisted by heatmg.
  • an acid and subsequently an aqueous impregnating liquid which is capable of causing an evolution of a gas upon contact with the acid may be introduced into the capillaries of the wood, the impregnating liquid beng introduced under pressure.
  • the impregnating liquid may be, e.g. an NaF solution containing an addition of alkali bicarbonate or alkali carbonate.
  • the reaction of the acid with the impregnating liquid will result in the evolution of a certain amount of gas so that the pressure in the liquid filament is increased to a value which does not exceed the external pressure while a predetermined temperature and the superatmospheric external pressure are maintained.
  • an acid, aqueous impregnating liquid e.g., an acidulated NaF solution
  • an auxiliary substance the contact of which with the acid results in an evolution of a gas.
  • This auxiliary substance may consist of a solution of alkali bicarbonate or alkali carbonate.
  • Example 1 2% by weight methylene chloride was added to an im pregnating liquid consisting of a tar oil at a temperature of 30 C. Under a pressure of 10 kg./sq. cm. above atmospheric pressure, the mixture was forced into the capillaries of the material to be impregnated. An hour later, the solution was heated to C. while the superatmospheric external pressure was maintained until the absorption of liquid had virtually ceased. The residual liquid was drained. The methylene chloride was removed from the capillaries by the application of a vacuum.
  • Example 2 Carbon dioxide was dissolved in an aqueous 4% solution of NaF at 20 C.
  • the resulting impregnating solution was forced under a pressure of 10 kg./ sq. cm. above atmospheric pressure into the material to be impregnated and an hour later was heated to 50 C. while the superatmospheric external pressure was maintained. This resulted in a liberation of the carbon dioxide from the impregnating solution so that the pressure in the capillaries was increased.
  • the absorption of liquid had virtually ceased, the residual liquid was drained and carbon dioxide was removed from the capillaries by evacuating.
  • the material to be impregnated was initially treated with carbon dioxide under a pressure of 1 kg./sq. cm. above atmospheric pressure.
  • the impregnating cylinder was then filled with the impregnating liquid under a higher pressure and the pressure was then reduced to the atmospheric pressure. This caused the carbon dioxide to flow in tiny bubbles through the impregnating liquid, in which part of the carbon dioxide becomes dissolved.
  • Example 3 The pressure was reduced by 600 millimeters mercury and methylene chloride was sucked into the capillaries until the partial vacuum had been eliminated. Methylene chloride condensed on the walls of the capillaries. Tar oil at 40 C. was then forced under a pressure of 10 kg./sq. cm. above atmospheric pressure into the capillaries of the material to be impregnated. After an hour, the tar oil was heated to 90 C. while the superatmospheric external pressure was maintained until the absorption of liquid had virtually ceased. As in Example 1, the capillaries contained tar oil with an admixture of methylene chloride. When the superatmospheric pressure had been removed, the residual liquid was drained and the methylene chloride was removed from the capillaries by evacuating.
  • Example 4 Wood was treated with carbon dioxide under a pressure of 4 kg/sq. cm. above atmospheric pressure. After 15 minutes, a 4% solution of NaF was forced into the wood under a pressure of kg./sq. cm. above atmospheric pressure. After one hour, the system was heated to 50 C. while the external liquid pressure was maintained until the absorption of liquid had virtually ceased. The surplus liquid and the carbon dioxide were then withdrawn by evacuating.
  • Example 5 After a reduction of pressure by 600 millimeters mercury, formic acid fumes were sucked into the capillaries until the partial vacuum had been eliminated. A neutral 4% NaF solution was mixed with a 4% sodium bicarbonate solution and was forced into the wood under a pressure of 10 kg./sq. cm. above atmospheric pressure. This pressure was maintained until the absorption of liquid had virtually ceased. Part of the liquid and the carbon dioxide gas which had been formed were then removed by evacuating.
  • a process of impregnating wood having impregnatable capillary channels which comprises the steps of maintaining an impregnating liquid consisting at least in part of a wood preservative in contact with the wood and applying thereto a superatmospheric pressure sufficient to cause said impregnating liquid to penetrate into said wood, providing in said wood a nongaseous thermally gasifiable auxiliary substance which is capable of evolving a gas at a predetermined temperature, the impregnation of said wood being carried out at a temperature below said predetermined temperature, heating said Wood to said predetermined temperature only after at least partial penetration of said liquid into the wood and when said auxiliary substance and said impregnating liquid are in contact with each other within said wood to evolve said gas and increase the pressure of said impregnating liquid in said wood, and maintaining said impregnating liquid outside said wood and in contact therewith under a superatmospheric pressure which is at least as high as the pressure of said impregnating liquid in said wood during the heating step.
  • auxiliary substance is a liquid which is easily evaporable by heating and said auxiliary substance and said impregnating liquid are heated in contact with each other within said wood to evaporate at least part of said auxiliary substance.
  • auxiliary substance is a low-boiling liquid which is soluble in said impregnating liquid and introduced into said wood as a solute in said impregnating liquid, said impregnating liquid containing said solute being heated within said wood to evaporate at least part of said solute.
  • said impregnating liquid is an aqueous solution and which comprises introducing carbon dioxide as said auxiliary substance as a solute in said impregnating liquid into said Wood, and heating said impregnating liquid containing said solute within said material to evolve carbon dioxide.
  • auxiliary substance is a low-boiling liquid and is introduced as a gas into said wood and caused to condense therein, whereafter the impregnating liquid is caused to penetrate into said material under said superatmospheric pressure to contact said condensed auxiliary substance, and at least part of said auxiliary substance is thereafter evaporated by said heating Within said Wood.

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Wood Science & Technology (AREA)
  • Forests & Forestry (AREA)
  • Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical And Physical Treatments For Wood And The Like (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
US542176A 1965-03-23 1966-03-21 Process of impregnating capillary materials such as wood,under pressure in a closed vessel Expired - Lifetime US3460979A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
AT263665A AT262588B (de) 1965-03-23 1965-03-23 Verfahren zum Imprägnieren von kapillaren Stoffen, z. B. Holz, im Kesseldruckverfahren

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Publication Number Publication Date
US3460979A true US3460979A (en) 1969-08-12

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US542176A Expired - Lifetime US3460979A (en) 1965-03-23 1966-03-21 Process of impregnating capillary materials such as wood,under pressure in a closed vessel

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US (1) US3460979A (de)
AT (1) AT262588B (de)
DE (1) DE1642197A1 (de)
FR (1) FR1475121A (de)
GB (1) GB1124392A (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4005039A (en) * 1974-06-28 1977-01-25 Research Corporation Curable compositions for bulking timber comprising (a) a modified polyol containing -0-3-alkyleneamido groups and (b) an amino resin precursor containing reactive N-hydroxymethyl groups
US4413024A (en) * 1980-03-17 1983-11-01 Fuji Kogyo Company, Limited Method for chemical treatment of woods
US5797332A (en) * 1995-08-11 1998-08-25 Callidus Technologies, Inc. Closed loop gasification drying system
FR2770171A1 (fr) * 1997-10-27 1999-04-30 Commissariat Energie Atomique Procede et installation de traitement d'un materiau poreux par un produit d'impregnation
US6471608B1 (en) 2001-10-11 2002-10-29 Joseph D. Mitchell Breakage-resistant baseball bat and production thereof

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1937417A (en) * 1930-08-20 1933-11-28 Warren Brothers Company Method of impregnating concrete bodies and porous ceramic products with bituminous material
US1993434A (en) * 1932-12-13 1935-03-05 Hercules Powder Co Ltd Method for impregnating carbonaceous material
US2740728A (en) * 1954-01-25 1956-04-03 Dow Chemical Co Production of resin-impregnated porous bodies

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1937417A (en) * 1930-08-20 1933-11-28 Warren Brothers Company Method of impregnating concrete bodies and porous ceramic products with bituminous material
US1993434A (en) * 1932-12-13 1935-03-05 Hercules Powder Co Ltd Method for impregnating carbonaceous material
US2740728A (en) * 1954-01-25 1956-04-03 Dow Chemical Co Production of resin-impregnated porous bodies

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4005039A (en) * 1974-06-28 1977-01-25 Research Corporation Curable compositions for bulking timber comprising (a) a modified polyol containing -0-3-alkyleneamido groups and (b) an amino resin precursor containing reactive N-hydroxymethyl groups
US4413024A (en) * 1980-03-17 1983-11-01 Fuji Kogyo Company, Limited Method for chemical treatment of woods
US5797332A (en) * 1995-08-11 1998-08-25 Callidus Technologies, Inc. Closed loop gasification drying system
FR2770171A1 (fr) * 1997-10-27 1999-04-30 Commissariat Energie Atomique Procede et installation de traitement d'un materiau poreux par un produit d'impregnation
US6471608B1 (en) 2001-10-11 2002-10-29 Joseph D. Mitchell Breakage-resistant baseball bat and production thereof

Also Published As

Publication number Publication date
AT262588B (de) 1968-06-25
DE1642197A1 (de) 1971-07-08
GB1124392A (en) 1968-08-21
FR1475121A (fr) 1967-03-31

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