CA1290909C - Process for chemically hardening wood and treatment solution therefor - Google Patents
Process for chemically hardening wood and treatment solution thereforInfo
- Publication number
- CA1290909C CA1290909C CA000529190A CA529190A CA1290909C CA 1290909 C CA1290909 C CA 1290909C CA 000529190 A CA000529190 A CA 000529190A CA 529190 A CA529190 A CA 529190A CA 1290909 C CA1290909 C CA 1290909C
- Authority
- CA
- Canada
- Prior art keywords
- wood
- loweralkanolamine
- pulping
- lignin
- vapor phase
- Prior art date
- Legal status (The legal status 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 status listed.)
- Expired - Lifetime
Links
- 239000002023 wood Substances 0.000 title claims abstract description 52
- 238000000034 method Methods 0.000 title claims abstract description 23
- 238000011282 treatment Methods 0.000 title claims description 14
- 238000004537 pulping Methods 0.000 claims abstract description 28
- 229920005610 lignin Polymers 0.000 claims abstract description 27
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 21
- 239000011121 hardwood Substances 0.000 claims abstract description 15
- 229920002678 cellulose Polymers 0.000 claims abstract description 11
- 239000001913 cellulose Substances 0.000 claims abstract description 10
- 230000003647 oxidation Effects 0.000 claims abstract description 7
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 7
- 239000002253 acid Substances 0.000 claims abstract description 6
- 150000003839 salts Chemical class 0.000 claims abstract description 5
- 150000001875 compounds Chemical class 0.000 claims abstract description 4
- 239000012670 alkaline solution Substances 0.000 claims abstract description 3
- 239000007795 chemical reaction product Substances 0.000 claims abstract description 3
- 239000000243 solution Substances 0.000 claims description 18
- 239000012808 vapor phase Substances 0.000 claims description 16
- 238000000280 densification Methods 0.000 claims description 10
- 230000001413 cellular effect Effects 0.000 claims description 9
- HZAXFHJVJLSVMW-UHFFFAOYSA-N 2-Aminoethan-1-ol Chemical group NCCO HZAXFHJVJLSVMW-UHFFFAOYSA-N 0.000 claims description 8
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 5
- 239000012466 permeate Substances 0.000 claims description 5
- 238000003825 pressing Methods 0.000 claims description 4
- 239000007788 liquid Substances 0.000 claims description 3
- 238000012691 depolymerization reaction Methods 0.000 claims description 2
- 239000007921 spray Substances 0.000 claims description 2
- 239000000126 substance Substances 0.000 abstract description 21
- 238000000926 separation method Methods 0.000 abstract description 4
- 239000011122 softwood Substances 0.000 abstract description 4
- 239000011120 plywood Substances 0.000 description 22
- 229920003043 Cellulose fiber Polymers 0.000 description 11
- 239000000463 material Substances 0.000 description 11
- 229910001868 water Inorganic materials 0.000 description 11
- 235000010980 cellulose Nutrition 0.000 description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 9
- 210000004027 cell Anatomy 0.000 description 8
- 229920005989 resin Polymers 0.000 description 7
- 239000011347 resin Substances 0.000 description 7
- 238000004519 manufacturing process Methods 0.000 description 6
- 239000000853 adhesive Substances 0.000 description 5
- 230000001070 adhesive effect Effects 0.000 description 5
- 241000894007 species Species 0.000 description 5
- 239000000835 fiber Substances 0.000 description 4
- 229920001169 thermoplastic Polymers 0.000 description 4
- 239000004416 thermosoftening plastic Substances 0.000 description 4
- 239000007864 aqueous solution Substances 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 239000002655 kraft paper Substances 0.000 description 3
- 229920000642 polymer Polymers 0.000 description 3
- 239000011435 rock Substances 0.000 description 3
- 241000219000 Populus Species 0.000 description 2
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical compound OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- 210000003850 cellular structure Anatomy 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 239000003365 glass fiber Substances 0.000 description 2
- 229910052500 inorganic mineral Inorganic materials 0.000 description 2
- 238000011835 investigation Methods 0.000 description 2
- 239000011707 mineral Substances 0.000 description 2
- 229920000058 polyacrylate Polymers 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 229920001187 thermosetting polymer Polymers 0.000 description 2
- 239000010875 treated wood Substances 0.000 description 2
- -1 e.g. Substances 0.000 description 1
- JZQLRTAGAUZWRH-UHFFFAOYSA-N 2-aminoethanol;hydrate Chemical compound [OH-].[NH3+]CCO JZQLRTAGAUZWRH-UHFFFAOYSA-N 0.000 description 1
- 235000007173 Abies balsamea Nutrition 0.000 description 1
- 241000219495 Betulaceae Species 0.000 description 1
- 241000218645 Cedrus Species 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 240000008790 Musa x paradisiaca Species 0.000 description 1
- 235000018290 Musa x paradisiaca Nutrition 0.000 description 1
- 241000218657 Picea Species 0.000 description 1
- 235000008331 Pinus X rigitaeda Nutrition 0.000 description 1
- 241000018646 Pinus brutia Species 0.000 description 1
- 235000011613 Pinus brutia Nutrition 0.000 description 1
- 241000183024 Populus tremula Species 0.000 description 1
- 241000218685 Tsuga Species 0.000 description 1
- 230000002730 additional effect Effects 0.000 description 1
- 150000001720 carbohydrates Chemical group 0.000 description 1
- 235000014633 carbohydrates Nutrition 0.000 description 1
- 210000002421 cell wall Anatomy 0.000 description 1
- 230000009194 climbing Effects 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 239000008151 electrolyte solution Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 238000009408 flooring Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000007373 indentation Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 239000003317 industrial substance Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000011328 necessary treatment Methods 0.000 description 1
- 239000000123 paper Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N phenol group Chemical group C1(=CC=CC=C1)O ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 235000000346 sugar Nutrition 0.000 description 1
- 150000008163 sugars Chemical class 0.000 description 1
- 235000011149 sulphuric acid Nutrition 0.000 description 1
- 229920005992 thermoplastic resin Polymers 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 238000009966 trimming Methods 0.000 description 1
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C3/00—Pulping cellulose-containing materials
- D21C3/04—Pulping cellulose-containing materials with acids, acid salts or acid anhydrides
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C3/00—Pulping cellulose-containing materials
- D21C3/003—Pulping cellulose-containing materials with organic compounds
Landscapes
- Chemical And Physical Treatments For Wood And The Like (AREA)
- Paper (AREA)
Abstract
Abstract of the Disclosure A pulping agent for the chemical separation of lignin from cellulose in wood without damage to either component is disclosed. The pulping agent comprises the reaction product of (a) a loweralkanol-amine with (b) a compound produced by electrolytic oxidation of the loweralkanolamine in an aqueous alkaline solution containing an acid addition salt of the loweralkanolamine. Also disclosed are processes utilizing such a pulping agent for chemically debarking whole logs as well as for converting soft wood into hard wood.
Description
~go~
The present invention relates to a process for the treatment of soft wood to produce hard wood, and to a treatment solution therefor.
Wood is composed of two main constituents:
1. cellulose in the form of fibers; and 2. lignin which acts as an adheslve or resin to bind the cellulose fibers together.
The mechanical strength of wood is derived from its unique structure. FIBERGLAS (trade mark) obtains its mechanical properties from a combination of glass fibers and a bonding resin. The glass fibers provide tensile strength and elasticity, and the resin binds the fibers together in a solid form. The structure of wood is similar; the cellulose fibers are linear chains of carbohydrates bonded together with a phenolic type of resin, the lignin.
Cellulose fibers derived from wood have been a major source of a very important industrial chemical called "chemical cellulose". Chemical cellulose is used to produce a wide variety of commercial products, e.g., cardboard, newsprint, writing paper, plastics, explo-sives, etc.
The production of hard wood evolved from a series of investigations carried out into the nature of cellulose fibers and lignin. These investigations were - pursued because of the difficulties associated with the industrial production of sulfite and kraft chemical celluloses, normally termed "pulps".
Both the sulfite and kraft processes use harsh and polluting chemicals. The use of harsh chemicals produces low yields and damaged cellulose fibers. The ~ ~90~19 resin, or lignin, a potentially valuable chemical, is completely destroyed. The only industrial use for the lignin residues utilized today is for the production of steam.
Applicant's extensive studies on the chemical structure of cellulose and lignin and the toxic nature of both the kraft and suLflte processes led to the develop-ment of a pulping process utilizing a unique pulping agent, enabling the chemical separation of lignin from cellulose in wood without damage to either component.
Accordingly, it is an object of the present invention to provide a pulping agent and a process utili7.ing same, enabling the chemical separation of lignin from cellulose in wood without damage to either component, and thus the production of high yields of undamaged chemical cellulose and undamaged lignin.
It is a further object of the invention to provide various processes utilizing such a pulping agent, for example, for the chemical debarking of whole logs or the chemical hardening of soft wood by pressing to produce a very dense hard wood material.
According to one aspect of the invention, there is thus provided a pulping agent for the chemical separation of lignin from cellulose in wood without damage to either component, which pulping agent comprises the reaction product of (a) a loweralkanolamine with (b) a compound produced by electrolytic oxidation of the loweralkanolamine in an aqueous alkaline solution containing an acid addition salt of the loweralkanol-amine.
~ -2-9()9(!~
The above pulping agent is prepared, in accordance with the invention, by first dissolving in water a predetermined amount of a loweralkanolamine such as monoethanolamine to form an aqueous solution thereof, then adding an aqueous solution of a strong mineral acid such as sulfuric acid to the aqueous solution of lower-alkanolamine to neutrality (i.e. pH ~ 7). An excess of the loweralkanolamine is added, thereby providing an alkaline pH. A pair of electrodes are immersed into the resulting solution to form an electrolytic cell and DC
electric current is passed through the cell between the electrodes thereof for a period of time sufficient to allow the loweralkanolamine to undergo anodic oxidation, the resultlng oxidation product reacting with the excess loweralkanolamine present in the cell to produce the desired pulping agent.
When using monoethanolamine as an example of suitable loweralkanolamine, the following reactions are believed to take place:
1. Dissolution of the monoethanolamine in water:
H0-CH2-CH2-NH2 + H20 H0-CH2-CH2-NH3 + OH
2. Addition of a strong mineral acid (e.g. H2SO4) to the monoethanolamine-water solution to neutrality:
H0 ~ CH2 ~ CH2 ~ NH3 + OH + H + HSO
2 CH2 - /N:H - SO4H + H2O
Radical i-"''' lX~
The above radical conducts electric current and allows the cell to operate at high efficiencies. Normal water solutions of monoethanolamine are poor conductors of electric current.
The present invention relates to a process for the treatment of soft wood to produce hard wood, and to a treatment solution therefor.
Wood is composed of two main constituents:
1. cellulose in the form of fibers; and 2. lignin which acts as an adheslve or resin to bind the cellulose fibers together.
The mechanical strength of wood is derived from its unique structure. FIBERGLAS (trade mark) obtains its mechanical properties from a combination of glass fibers and a bonding resin. The glass fibers provide tensile strength and elasticity, and the resin binds the fibers together in a solid form. The structure of wood is similar; the cellulose fibers are linear chains of carbohydrates bonded together with a phenolic type of resin, the lignin.
Cellulose fibers derived from wood have been a major source of a very important industrial chemical called "chemical cellulose". Chemical cellulose is used to produce a wide variety of commercial products, e.g., cardboard, newsprint, writing paper, plastics, explo-sives, etc.
The production of hard wood evolved from a series of investigations carried out into the nature of cellulose fibers and lignin. These investigations were - pursued because of the difficulties associated with the industrial production of sulfite and kraft chemical celluloses, normally termed "pulps".
Both the sulfite and kraft processes use harsh and polluting chemicals. The use of harsh chemicals produces low yields and damaged cellulose fibers. The ~ ~90~19 resin, or lignin, a potentially valuable chemical, is completely destroyed. The only industrial use for the lignin residues utilized today is for the production of steam.
Applicant's extensive studies on the chemical structure of cellulose and lignin and the toxic nature of both the kraft and suLflte processes led to the develop-ment of a pulping process utilizing a unique pulping agent, enabling the chemical separation of lignin from cellulose in wood without damage to either component.
Accordingly, it is an object of the present invention to provide a pulping agent and a process utili7.ing same, enabling the chemical separation of lignin from cellulose in wood without damage to either component, and thus the production of high yields of undamaged chemical cellulose and undamaged lignin.
It is a further object of the invention to provide various processes utilizing such a pulping agent, for example, for the chemical debarking of whole logs or the chemical hardening of soft wood by pressing to produce a very dense hard wood material.
According to one aspect of the invention, there is thus provided a pulping agent for the chemical separation of lignin from cellulose in wood without damage to either component, which pulping agent comprises the reaction product of (a) a loweralkanolamine with (b) a compound produced by electrolytic oxidation of the loweralkanolamine in an aqueous alkaline solution containing an acid addition salt of the loweralkanol-amine.
~ -2-9()9(!~
The above pulping agent is prepared, in accordance with the invention, by first dissolving in water a predetermined amount of a loweralkanolamine such as monoethanolamine to form an aqueous solution thereof, then adding an aqueous solution of a strong mineral acid such as sulfuric acid to the aqueous solution of lower-alkanolamine to neutrality (i.e. pH ~ 7). An excess of the loweralkanolamine is added, thereby providing an alkaline pH. A pair of electrodes are immersed into the resulting solution to form an electrolytic cell and DC
electric current is passed through the cell between the electrodes thereof for a period of time sufficient to allow the loweralkanolamine to undergo anodic oxidation, the resultlng oxidation product reacting with the excess loweralkanolamine present in the cell to produce the desired pulping agent.
When using monoethanolamine as an example of suitable loweralkanolamine, the following reactions are believed to take place:
1. Dissolution of the monoethanolamine in water:
H0-CH2-CH2-NH2 + H20 H0-CH2-CH2-NH3 + OH
2. Addition of a strong mineral acid (e.g. H2SO4) to the monoethanolamine-water solution to neutrality:
H0 ~ CH2 ~ CH2 ~ NH3 + OH + H + HSO
2 CH2 - /N:H - SO4H + H2O
Radical i-"''' lX~
The above radical conducts electric current and allows the cell to operate at high efficiencies. Normal water solutions of monoethanolamine are poor conductors of electric current.
3. Electrolytic reactions when DC electric current is passed through the cell:
i. Cathode: hydrogen gas is evolved at the cathode:
e 2 H + 2 e + Electrical Energy ~ H2 (gas) ii. Anode: the monoethanolamine undergoes 1~ oxidation at the anode to produce species believed to be:
H2N - CH2 ~ CH2 - OH + ~O] (oxidation) -H OH
N2N - CH2 - C = 0 and H2N - CH2 - C = 0 The above compounds react with the excess monoethanolamine which is preferably present in a weight ratio of about 5 times the original amount of monoetha-nolamine, to produce a polymer which ls distilled from the electrolytic solution; this polymer is believed to be of the following type:
OH
H
H N - CH - CH - OH
H
The pulping agent prepared as above is espe-cially suited for the vapor phase pressure treatment of whole logs of various wood species, including deciduous ~,~90~
(short-fibered) species such as alder, aspen, cottonwood, poplar, etc., and evergreen species such as hemlock, spruce, cedar, pine, etc.
It has been found quite surprisingly that when whole unbarked logs are treated with a pulping agent as defined above in vapor phase and under pressure, all species of logs are chemically debarked, the logs are pulped and the cell structure of the wood is altered, enabling the wood to be densified by subsequent pressing.
Even though the logs are treated in the vapor phase, the chemical vapors remove water and some wood components, such as lignin and wood sugars, and these condense in the liquid phase.
These very unique chemical reactlons alter the chemical nature of both the bark and the wood. The resulting chemical action destroys the bark-to-sapwood bonds so that the bark literally falls off the log or the log may be peeled like a banana, leavlng a clean, de-barked log.
This is a significant advance in wood techno-logy as pure chemical bark and whole peeled logs may be readily obtained. The chemically altered bark may be manufactured into high-density fuel and strong, dense bark boards, similar to particle boards.
Accordingly, the present invention provides in another aspect thereof a process for the vapor phase pressure treatment of whole unbarked logs, which com-prises treating the logs with a pulping agent as defined hereinabove in vapor phase, under heat and pressure ~ ~9u~9 conditions and for a period of time sufficient to allow the vapors of pulping agent -to permeate the logs and cause chemical debarking thereof.
Preferably, the vapor phase pressure treatment is carried in a pressure vessel at a pressure ranging from about 25 psi to about 50 psi, preferably 25-35 psi, the vessel being heated at a temperature sufficient to develop s~ch a pressure, e.g. about 275-350F. The pressure is generally maintained for a period of about lO
to 15 minutes.
After the necessary treatment period has elapsed, the treated logs are removed from the pressure vessel and then moved to a debarking unit. Due to the chemical debarking which takes place during the vapor phase pressure treatment, the bark separates very easily, producing clean and undamaged debarked logs.
If a dense hard wood material is desired, the debarked logs while still hot are pressed in a hydraulic press and maintained in a compressed state until cool, the pressure applied varying according to density and thickness desired. Prior to being pressed, the debarked logs may optionally be cut into standard lumber sizes, depending on size of log and the lumber desired.
The vapor phase pressure treatment according to the invention is operative not only on green wood, but on kiln-dried wood as well. Thus, both vapor phase pressure treated green wood and vapor phase pressure treated dried wood can be hardened according to the invention.
~ ~9U9C~9 The utilization of relatively low hydraulie pressures required to produce hard wood aceording to the invention confirms that the pulping agent utilized chemieally reaets with the lignin and eellulose consti-tuents of wood and profoundly alters the cellular struc-ture of the wood. These chemieal reaetions make the manufaeture of hard wood technically and economically feasible.
The present invention also provides, in a further aspect thereof, a pulping process for chemically separating lignin from eellulose in wood without damage to either component, which comprlses treating wood with a pulping agent as defined hereinbefore in vapor phase under heat and pressure conditions and for a period of time suffieient to allow the vapors of pulping agent to permeate the wood and cause a lignin depolymerization reaction, whereby a complex component of depolymerized lignin is extracted and collected in the form of a liquid pulping extract.
The temperature and pressure conditions as well as the treatment period are essentially the same as those mentioned above for chemieally debarking whole logs.
It has been found quite unexpeetedly that the pulping extraet which is derived from the above pulping proeess and eontains a eomplex eomponent of depolymerized lignin ean be used as a eellular densifieation solution for wood, enabling soft wood to be eonverted into hard wood.
~. Z909{X~
It has been observed that the pulping agent according to the invention reacts with the lignin in the wood and removes a bridging group within the polymer structure of lignin which causes the lignin to convert from a polymerized thermosetting resin to a type of monomeric thermoplastic form.
This type of monomeric thermoplastic form of lignin no longer binds the cellulose fibers together and therefore the cellulose fibers can be separated without damage into the form of pulp. In this state, the fibers are no longer stiff, as in the original wood, but rather take on a soft and pliable form, much like well-cooked spaghetti.
The cellular densification solution is thus essentially a solution of complex component of monomeric liqnin. When such a solution is applied by brush or spray to raw wood, a very simple procedure, and treated wood is then placed in a hydraulic press and heated, the solution vaporizes under the influence of heat and permeates the cell structure of the wood at a very rapid rate.
Two reactions take place. One end of the molecule of the hardening agent, having a reactive bond-cleaving structure, reacts with the bridging group in the wood lignin and converts the resin to a thermo-plastic form. The other end of the molecule, which contains a reactive bridging group, bridges across the cellulose fibers and chains the fibers together.
~ 2909(~
The chain structure is extremely strong and chemically stable. The bridging group also displaces the water molecules which are chemically bonded in the cell structure of the wood and which hold the cellulose fibers together.
Water molecules are very rigid, while the newly-introduced bridging group molecules are both strong and flexible.
When hydraulic pressure is applied to treated wood, densification, displayed by a decrease in thick-ness, takes place. The amount of energy required to bring about this densification is quite low.
The altered thermoplastic resin, in heated form, shows very little mechanical resistance. The unbridged water also displays low mechanical resistance.
The water molecules are no longer chemically bonded to the cell walls and therefore liquid water now flows from the structure of the wood as from a sponge.
Hard wood is manufactured by allowing the pressed wood to remain ln the compressed state until cool. The thermoplastic lignin, upon cooling, reverts to its thermosetting polymeric form, which strongly stabi-lizes the structure of the newly-densified wood. Addi-tional strength is incorporated into the wood by bringing the cellulose fibers closer together, thus creating additional bonding between the cellulose fibers and the bridging chain as the bridging chain loops through the cellular structure.
This phenomenon theoretically explains the increase in hardness as the thickness of the original wood decreases.
~x9o9~9 The stabilization of the hard wood is advanta-geously accomplished by the use of a locking mould. On reaching the desired thickness in the hydraulic press, the mould is locked and removed from the press. The mouid is allowed to cool for approximately one hour; the hard wood sample is then removed and the mould can be used for another wood sample. The use of locking moulds thus enables high volume production of hard wood.
It has also been found according to the invention, that the cellular densification solution when mixed with an acrylic polymer can be formulated into a wood adhesive having exceptional bonding properties.
Thus, for example, instead of taking a single piece of wood of three inches (3.0") thickness, treating the piece with the cellular denslfication solution and then heat pressing to a thickness of two inches (2.0"), lt is possible to take two pieces of wood, 1.5" thickness a piece, apply a mixture of cellular densification solution and the acrylic polymer as an adhesive between the pieces only, and press the two pieces with the adhesive therebetween to produce the desired 2.0" thick hard wood. A fusion of the two pieces takes place produc-ing a solid piece of hard wood.
Such a wood adhesive can also be used with advantage in the manufacture of plywood, as may be seen from the following non-limiting examples which further illustrate the invention.
Several sheets of plywood were manufactured from wood veneers utilizing a plywood adhesive formulated from the cellular densification solution.
u9(~
Five layers of 1/10" veneer were placed in a hydraulic press and pressed into a plywood sheet.
The resulting plywood was surprisingly diffe-rent from normal plywood. Instead of obtaining a sheet of plywood of ~" thickness, the resulting plywood sheet was only ~" thick. The physical properties of this new form of plywood were also very different from ordinary plywood.
The surface of the new form of plywood was hard and smooth. Saw trimming of the sheet showed that all of the veneers had decreased in thickness to the same degree, to one-half of their original thickness. The plywood exhibited very high impact resistance. In a series of tests, the plywood was struck as hard as possible with a ball-peen hammer, to determine impact and puncture resistance. The surface of the plywood was barely dented.
Ordinary plywood treated in this same manner had deep indentation and in some cases the head of the ball-peen hammer completely punctured the ordinary plywood.
The impact and puncture resistance properties suggests the material can be utilized in the manufacture of shipping crates, boats, car bodies and armor plate, flooring, etc. It is also believed that the material can be suitable as a bearing material, to form "wooden"
bearings.
~ ~U~t(~
A miniature "jeep" was constructed utilizing the plywood produced in Example 1, for body material and bearings. Wheel hubs were machined from several layers of the plywood and placed on axles made from aluminum tubing.
The jeep was taken to and driven over the top of a mountain range, over the roughest road in the area.
The first ten miles consisted of washouts, boulders, logs and bush. The jeep was driven over this section to test impact against rocks, logs and bush.
The second ten-mile section was somewhat more passable and the jeep was driven over this section at higher speed to determine the resistance of the bearings to high-speed rotation and continuous impact of the wheels against boulders and potholes.
At the end of the run, the bearings were ~ examined for generated heat and wear.
¦ The bearings were found to be cool, indicating a low friction coefficient between the plywood and the aluminum axle. The bearings were next examined for wear.
The bearings were found to be tight, showing no signs of wear, yet rotated freely, indicating the new ' form of plywood had self-lubricating properties.
Examination of the body showed no punctures or cracks in the plywood. The material had withstood impact against rocks, logs and bush; it had resisted torsion and twisting, climbing over rocks and logs. In general, the ! material exhibited several excellent properties. Another experiment demonstrated even further the possibilities of this new form of plywood.
~ X90~Q~
A 10-shot clip of .22 caliber Long Rifle cartridges was fired at very close range from a semi-automatic rifle into the material. The point of impact was examined.
It was discovered that the bullets had pene-trated only about 1/8" into the material and had fused into a single ball of lead. The material thus exhibited the properties of a form of armor plate.
i. Cathode: hydrogen gas is evolved at the cathode:
e 2 H + 2 e + Electrical Energy ~ H2 (gas) ii. Anode: the monoethanolamine undergoes 1~ oxidation at the anode to produce species believed to be:
H2N - CH2 ~ CH2 - OH + ~O] (oxidation) -H OH
N2N - CH2 - C = 0 and H2N - CH2 - C = 0 The above compounds react with the excess monoethanolamine which is preferably present in a weight ratio of about 5 times the original amount of monoetha-nolamine, to produce a polymer which ls distilled from the electrolytic solution; this polymer is believed to be of the following type:
OH
H
H N - CH - CH - OH
H
The pulping agent prepared as above is espe-cially suited for the vapor phase pressure treatment of whole logs of various wood species, including deciduous ~,~90~
(short-fibered) species such as alder, aspen, cottonwood, poplar, etc., and evergreen species such as hemlock, spruce, cedar, pine, etc.
It has been found quite surprisingly that when whole unbarked logs are treated with a pulping agent as defined above in vapor phase and under pressure, all species of logs are chemically debarked, the logs are pulped and the cell structure of the wood is altered, enabling the wood to be densified by subsequent pressing.
Even though the logs are treated in the vapor phase, the chemical vapors remove water and some wood components, such as lignin and wood sugars, and these condense in the liquid phase.
These very unique chemical reactlons alter the chemical nature of both the bark and the wood. The resulting chemical action destroys the bark-to-sapwood bonds so that the bark literally falls off the log or the log may be peeled like a banana, leavlng a clean, de-barked log.
This is a significant advance in wood techno-logy as pure chemical bark and whole peeled logs may be readily obtained. The chemically altered bark may be manufactured into high-density fuel and strong, dense bark boards, similar to particle boards.
Accordingly, the present invention provides in another aspect thereof a process for the vapor phase pressure treatment of whole unbarked logs, which com-prises treating the logs with a pulping agent as defined hereinabove in vapor phase, under heat and pressure ~ ~9u~9 conditions and for a period of time sufficient to allow the vapors of pulping agent -to permeate the logs and cause chemical debarking thereof.
Preferably, the vapor phase pressure treatment is carried in a pressure vessel at a pressure ranging from about 25 psi to about 50 psi, preferably 25-35 psi, the vessel being heated at a temperature sufficient to develop s~ch a pressure, e.g. about 275-350F. The pressure is generally maintained for a period of about lO
to 15 minutes.
After the necessary treatment period has elapsed, the treated logs are removed from the pressure vessel and then moved to a debarking unit. Due to the chemical debarking which takes place during the vapor phase pressure treatment, the bark separates very easily, producing clean and undamaged debarked logs.
If a dense hard wood material is desired, the debarked logs while still hot are pressed in a hydraulic press and maintained in a compressed state until cool, the pressure applied varying according to density and thickness desired. Prior to being pressed, the debarked logs may optionally be cut into standard lumber sizes, depending on size of log and the lumber desired.
The vapor phase pressure treatment according to the invention is operative not only on green wood, but on kiln-dried wood as well. Thus, both vapor phase pressure treated green wood and vapor phase pressure treated dried wood can be hardened according to the invention.
~ ~9U9C~9 The utilization of relatively low hydraulie pressures required to produce hard wood aceording to the invention confirms that the pulping agent utilized chemieally reaets with the lignin and eellulose consti-tuents of wood and profoundly alters the cellular struc-ture of the wood. These chemieal reaetions make the manufaeture of hard wood technically and economically feasible.
The present invention also provides, in a further aspect thereof, a pulping process for chemically separating lignin from eellulose in wood without damage to either component, which comprlses treating wood with a pulping agent as defined hereinbefore in vapor phase under heat and pressure conditions and for a period of time suffieient to allow the vapors of pulping agent to permeate the wood and cause a lignin depolymerization reaction, whereby a complex component of depolymerized lignin is extracted and collected in the form of a liquid pulping extract.
The temperature and pressure conditions as well as the treatment period are essentially the same as those mentioned above for chemieally debarking whole logs.
It has been found quite unexpeetedly that the pulping extraet which is derived from the above pulping proeess and eontains a eomplex eomponent of depolymerized lignin ean be used as a eellular densifieation solution for wood, enabling soft wood to be eonverted into hard wood.
~. Z909{X~
It has been observed that the pulping agent according to the invention reacts with the lignin in the wood and removes a bridging group within the polymer structure of lignin which causes the lignin to convert from a polymerized thermosetting resin to a type of monomeric thermoplastic form.
This type of monomeric thermoplastic form of lignin no longer binds the cellulose fibers together and therefore the cellulose fibers can be separated without damage into the form of pulp. In this state, the fibers are no longer stiff, as in the original wood, but rather take on a soft and pliable form, much like well-cooked spaghetti.
The cellular densification solution is thus essentially a solution of complex component of monomeric liqnin. When such a solution is applied by brush or spray to raw wood, a very simple procedure, and treated wood is then placed in a hydraulic press and heated, the solution vaporizes under the influence of heat and permeates the cell structure of the wood at a very rapid rate.
Two reactions take place. One end of the molecule of the hardening agent, having a reactive bond-cleaving structure, reacts with the bridging group in the wood lignin and converts the resin to a thermo-plastic form. The other end of the molecule, which contains a reactive bridging group, bridges across the cellulose fibers and chains the fibers together.
~ 2909(~
The chain structure is extremely strong and chemically stable. The bridging group also displaces the water molecules which are chemically bonded in the cell structure of the wood and which hold the cellulose fibers together.
Water molecules are very rigid, while the newly-introduced bridging group molecules are both strong and flexible.
When hydraulic pressure is applied to treated wood, densification, displayed by a decrease in thick-ness, takes place. The amount of energy required to bring about this densification is quite low.
The altered thermoplastic resin, in heated form, shows very little mechanical resistance. The unbridged water also displays low mechanical resistance.
The water molecules are no longer chemically bonded to the cell walls and therefore liquid water now flows from the structure of the wood as from a sponge.
Hard wood is manufactured by allowing the pressed wood to remain ln the compressed state until cool. The thermoplastic lignin, upon cooling, reverts to its thermosetting polymeric form, which strongly stabi-lizes the structure of the newly-densified wood. Addi-tional strength is incorporated into the wood by bringing the cellulose fibers closer together, thus creating additional bonding between the cellulose fibers and the bridging chain as the bridging chain loops through the cellular structure.
This phenomenon theoretically explains the increase in hardness as the thickness of the original wood decreases.
~x9o9~9 The stabilization of the hard wood is advanta-geously accomplished by the use of a locking mould. On reaching the desired thickness in the hydraulic press, the mould is locked and removed from the press. The mouid is allowed to cool for approximately one hour; the hard wood sample is then removed and the mould can be used for another wood sample. The use of locking moulds thus enables high volume production of hard wood.
It has also been found according to the invention, that the cellular densification solution when mixed with an acrylic polymer can be formulated into a wood adhesive having exceptional bonding properties.
Thus, for example, instead of taking a single piece of wood of three inches (3.0") thickness, treating the piece with the cellular denslfication solution and then heat pressing to a thickness of two inches (2.0"), lt is possible to take two pieces of wood, 1.5" thickness a piece, apply a mixture of cellular densification solution and the acrylic polymer as an adhesive between the pieces only, and press the two pieces with the adhesive therebetween to produce the desired 2.0" thick hard wood. A fusion of the two pieces takes place produc-ing a solid piece of hard wood.
Such a wood adhesive can also be used with advantage in the manufacture of plywood, as may be seen from the following non-limiting examples which further illustrate the invention.
Several sheets of plywood were manufactured from wood veneers utilizing a plywood adhesive formulated from the cellular densification solution.
u9(~
Five layers of 1/10" veneer were placed in a hydraulic press and pressed into a plywood sheet.
The resulting plywood was surprisingly diffe-rent from normal plywood. Instead of obtaining a sheet of plywood of ~" thickness, the resulting plywood sheet was only ~" thick. The physical properties of this new form of plywood were also very different from ordinary plywood.
The surface of the new form of plywood was hard and smooth. Saw trimming of the sheet showed that all of the veneers had decreased in thickness to the same degree, to one-half of their original thickness. The plywood exhibited very high impact resistance. In a series of tests, the plywood was struck as hard as possible with a ball-peen hammer, to determine impact and puncture resistance. The surface of the plywood was barely dented.
Ordinary plywood treated in this same manner had deep indentation and in some cases the head of the ball-peen hammer completely punctured the ordinary plywood.
The impact and puncture resistance properties suggests the material can be utilized in the manufacture of shipping crates, boats, car bodies and armor plate, flooring, etc. It is also believed that the material can be suitable as a bearing material, to form "wooden"
bearings.
~ ~U~t(~
A miniature "jeep" was constructed utilizing the plywood produced in Example 1, for body material and bearings. Wheel hubs were machined from several layers of the plywood and placed on axles made from aluminum tubing.
The jeep was taken to and driven over the top of a mountain range, over the roughest road in the area.
The first ten miles consisted of washouts, boulders, logs and bush. The jeep was driven over this section to test impact against rocks, logs and bush.
The second ten-mile section was somewhat more passable and the jeep was driven over this section at higher speed to determine the resistance of the bearings to high-speed rotation and continuous impact of the wheels against boulders and potholes.
At the end of the run, the bearings were ~ examined for generated heat and wear.
¦ The bearings were found to be cool, indicating a low friction coefficient between the plywood and the aluminum axle. The bearings were next examined for wear.
The bearings were found to be tight, showing no signs of wear, yet rotated freely, indicating the new ' form of plywood had self-lubricating properties.
Examination of the body showed no punctures or cracks in the plywood. The material had withstood impact against rocks, logs and bush; it had resisted torsion and twisting, climbing over rocks and logs. In general, the ! material exhibited several excellent properties. Another experiment demonstrated even further the possibilities of this new form of plywood.
~ X90~Q~
A 10-shot clip of .22 caliber Long Rifle cartridges was fired at very close range from a semi-automatic rifle into the material. The point of impact was examined.
It was discovered that the bullets had pene-trated only about 1/8" into the material and had fused into a single ball of lead. The material thus exhibited the properties of a form of armor plate.
Claims (12)
1. A pulping process for chemically separating lignin from cellulose in wood without substantial damage to either component, which comprises subjecting wood to a vapor phase pressure treatment with a pulping agent comprising the reaction product of (a) a loweralkanolamine with (b) a compound produced by electrolytic oxidation of the loweralkanolamine in an aqueous alkaline solution containing an acid addition salt of the loweralkanolamine, said vapor phase pressure treatment being carried out under heat and pressure conditions and for a period of time sufficient to allow vapors of said pulping agent to permeate the wood and cause a lignin depolymerization reaction, whereby a complex component of depolymerized lignin is extracted and collected in the form of a liquid pulping extract.
2. A process as claimed in claim 1, wherein said vapor phase pressure treatment is carried out at a pressure ranging from about 25 psi to about 50 psi.
3. A process as claimed in claim 2, wherein said pressure is in the range of about 25 psi to about 35 psi.
4. A process as claimed in claim 2, wherein the vapor phase pressure treatment is carried out at a temperature of about 275° to about 350°F.
5. A process as claimed in claim 1, wherein the vapor phase pressure treatment is carried out for a period of about 10 to 15 minutes.
6. A process as claimed in claim 1, wherein said loweralkanolamine is monoethanolamine.
7. A process as claimed in claim 6, wherein said acid addition salt is an addition salt of the loweralkanolamine with sulfuric acid.
8. A cellular densification solution for hardening wood, which comprises a pulping extract containing a complex component of depolymerized lignin and produced by a process as defined in claim 1.
9. A process for producing hard wood, which comprises applying a cellular densification solution as defined in claim 8 onto a wood sample, heat pressing the wood sample thus treated to cause said solution to vaporize and permeate the wood, and maintaining the pressed wood in a compressed state until cool.
10. A process as claimed in claim 9, wherein the cellular densification solution is applied by brush.
11. A process as claimed in claim 9, wherein the cellular densification solution is applied by spray.
12. A process as claimed in claim 9, wherein use is made of a locking mould for maintaining the pressed wood in a compressed state until cool.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000529190A CA1290909C (en) | 1987-02-06 | 1987-02-06 | Process for chemically hardening wood and treatment solution therefor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000529190A CA1290909C (en) | 1987-02-06 | 1987-02-06 | Process for chemically hardening wood and treatment solution therefor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1290909C true CA1290909C (en) | 1991-10-22 |
Family
ID=4134922
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000529190A Expired - Lifetime CA1290909C (en) | 1987-02-06 | 1987-02-06 | Process for chemically hardening wood and treatment solution therefor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1290909C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN118144055A (en) * | 2024-04-24 | 2024-06-07 | 河南农业大学 | A preparation method of formaldehyde-free high-performance glued wood |
-
1987
- 1987-02-06 CA CA000529190A patent/CA1290909C/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN118144055A (en) * | 2024-04-24 | 2024-06-07 | 河南农业大学 | A preparation method of formaldehyde-free high-performance glued wood |
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