Truncation of the distribution of modulus properties in natural populations of woods.

Abstract

The present disclosure is directed to methods for sorting wood veneer materials by property measurement and then improving the properties of veneer materials whose property values ​​are below a target threshold until those materials meet or exceed that threshold. In some aspects of the present disclosure, veneer materials are prepared, non-destructively measured, and sorted into a set of acceptable and unacceptable materials. The unacceptable set of materials can then be treated to improve the density and flexural modulus of the materials therein. Also disclosed herein are products and materials incorporating veneer materials treated according to the disclosed methods.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 63 / 400,332, filed August 23, 2022, which is incorporated herein by reference in its entirety.

[0002] Field The present disclosure relates to a method for improving the distribution of mechanical properties of wood veneer materials and veneer-based strand materials, as well as the resulting products. [Background technology]

[0003] background Wood products can be classified as structural or nonstructural. Structural wood products include softwood lumber, softwood glued laminated lumber, softwood plywood, laminated veneer lumber (LVL), I-joists, parallel strand lumber (PSL), laminated strand lumber (LSL), oriented strand board (OSB), and softwood plywood. Nonstructural wood products include particleboard, fiberboard, hardboard, and hardwood plywood. Structural wood products are differentiated based on their ability to support sustained building loads and, when used in residential and commercial buildings, primarily cover vertical members, horizontal members, diagonal members, and flooring, wall sheathing, and roof sheathing.

[0004] The strength and modulus properties of wood-based composites depend largely on the strength and modulus of the wood elements that make up the composite. Wood elements used in the manufacture of structural composites include veneers and strands. However, in most cases, a significant proportion of the veneers and strands produced at manufacturing sites have insufficient mechanical properties for certain structural wood applications. Therefore, there is a need for methods to improve the natural properties of this otherwise unsuitable portion of the material, and for products using materials with such improved properties.

[0005] Therefore, there is a need for methods to improve the natural properties of this otherwise unsuitable portion of the material, and for products using materials that have such improved properties. Summary of the Invention [Means for solving the problem]

[0006] Summary of the Invention Disclosed herein is a method for converting a population of veneer sheets, initially consisting of a mix of unacceptable and acceptable flexural modulus values, into a population of modified veneer sheets, in which all or most of the sheets have an acceptable flexural modulus. The method includes a first step of non-destructively measuring the stiffness of the veneer sheets within the initial population. In a second step, the initial population of veneer sheets is separated into a first group having flexural modulus values ​​above a target threshold and a second group having flexural modulus values ​​below the target threshold. In a third step, the wooden elements in the second group are subjected to a process to increase their flexural modulus values ​​above the target flexural modulus threshold.

[0007] One particular example relates to a method that includes subjecting a series of wood veneer pieces to non-destructive parallel-to-grain bending modulus measurements, the method further including sorting the veneer pieces into a first group including veneer pieces having modulus values ​​above a predetermined threshold and a second group including veneer pieces having modulus values ​​below the threshold, the method further including subjecting the veneer pieces in the second group to a process that increases the parallel-to-grain bending modulus values ​​above the predetermined threshold.

[0008] Certain embodiments further include a lignin degradation step and a compaction step.

[0009] Certain embodiments further include infiltrating the veneer with a filling solution to produce a treated veneer.

[0010] Certain embodiments further include impregnating the treated veneer with a water blocker.

[0011] Certain embodiments further include compressing the treated veneer along a thickness axis until the density of the treated veneer is in a first density range.

[0012] Certain embodiments further include reducing the moisture content of the treated veneer to a range of about 1-10%.

[0013] Certain embodiments further include compressing the treated veneer along the thickness axis until the density of the treated veneer is in a second density range.

[0014] One particular embodiment relates to a method for improving the mechanical properties of wood veneers. The method includes impregnating a wood veneer with a filler solution to produce a treated veneer and partially drying the treated veneer a first time. The method also includes impregnating the treated veneer with a water-blocking agent and partially drying the treated veneer a second time. The method also includes holding the treated veneer at a temperature in the range of 20-50°C and a pressure in the range of 100-1200 psi without fully curing the water-blocking agent until the density of the treated veneer is in the range of 900-1,100 kg / m3, and drying the treated veneer until the moisture content is in the range of 1%-10%.

[0015] The above and other objects, features, and advantages of the present disclosure will become more apparent from the following detailed description which proceeds with reference to the accompanying drawings. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic diagram illustrating a process for improving the material properties of rejected veneer and filament material according to one embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] Detailed Description Definition of Terms The following explanations of terms and abbreviations are provided to better describe the present disclosure and to guide those skilled in the art in practicing the present disclosure. As used herein, "comprising" means "including," and the singular forms "a" or "an" or "the" include plural references unless the context clearly dictates otherwise. The term "or" refers to a single element or a combination of two or more of the listed alternative elements, unless the context clearly dictates otherwise.

[0018] Unless otherwise explained, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although methods and materials similar or equivalent to those described herein can be used in practicing or testing this disclosure, suitable methods and materials are described below. The materials, methods, and examples are for illustrative purposes only and are not intended to be limiting. Other features of the present disclosure will be apparent from the following detailed description and claims.

[0019] Unless otherwise indicated, all numerical values ​​expressing amounts, percentages of ingredients, temperatures, times, and the like used in the specification or claims are understood to be modified by the term "about." Thus, unless otherwise indicated, either implicitly or explicitly, the numerical parameters recited are approximations that may depend on the desired properties sought and / or detection limits under standard testing conditions / methods, as known to those skilled in the art. Where directly and explicitly distinguishing the embodiments from the prior art discussed, the numerical values ​​of the embodiments are not approximations unless the word "about" is recited. Moreover, not all alternatives listed herein are necessarily equivalents.

[0020] Any feature described herein with respect to any embodiment may be combined with any other feature described in any one or more of the embodiments, unless otherwise stated.

[0021] In order to facilitate review of the various aspects of this disclosure, the following explanations of specific terms are provided.

[0022] Cure: In this disclosure, the term "cure," when used in reference to a monomer, indicates that the monomer undergoes multiple condensation or addition reactions and the resulting reaction product is a water-insoluble solid molecule.

[0023] Laminated Veneer Lumber: In this disclosure, the term laminated veneer lumber (or LVL) refers to a structural wood-based composite composed of multiple layers of veneer, where the veneer layers are bonded together using a structural adhesive and the grain gradient associated with each of the veneer layers is oriented in the same direction within the composite.

[0024] Laminated Strand Lumber: In this disclosure, the term laminated strand lumber (or LSL) refers to a structural wood-based composite composed of many long strands, where the strands have a length of approximately 6 to 15 inches and are bonded together using a structural adhesive, the grain gradient associated with each of the strands is approximately oriented along the length of the strand, and the orientation of all of the strands is approximately the same direction within the composite.

[0025] Parallel Strand Lumber: In this disclosure, the term parallel strand lumber (or PSL) refers to a structural wood-based composite composed of many long strands, where the strands have lengths of approximately 30 to 100 inches and are bonded together using a structural adhesive, the grain gradient associated with each of the strands is approximately oriented along the length of the strand, and the orientation of all of the strands is approximately the same direction within the composite.

[0026] Bending Modulus Parallel to Grain: In this disclosure, the term "bending modulus parallel to grain" refers to a calculated modulus, where the input values ​​for the calculation are determined from a flexure test method using a rectangular wood-based composite with a primary grain direction associated with its length axis, the composite having a width value (w) and a thickness value (t); the composite is placed on two support rods that are separated by a given distance, this distance having a specific span value (span); a downward force (F) is applied to the composite parallel to the thickness of the composite at the midpoint of the span, the applied force causes a downward deflection distance (d) at the midpoint of the composite, and the slope of the F / d relationship is determined; the bending modulus parallel to the grain is calculated as (slope x span) 3 ) multiplied by (4 × width × thickness 3 ) is calculated as the quotient divided by the product of

[0027] Oriented Strand Board: In this disclosure, the term oriented strand board (or OSB) refers to a structural wood-based composite composed of numerous short strands, wherein the strands are approximately 1-6 inches long, approximately 0.5-2.0 inches wide, and approximately 0.015-0.050 inches thick, and are bonded together using a structural adhesive; the composite has top and bottom major surfaces with three or more layers between the top and bottom major surfaces; the grain gradient associated with each of the strands is approximately oriented in the direction of the strand's length; the predominant orientation of the strand length in the outermost layers (top and bottom) is longitudinal, while the predominant orientation of the strand length in one or more of the middle layers (between the top and bottom layers) is transverse or has a random orientation; and wherein the longitudinal direction of the composite is offset 90 degrees from the transverse direction of the composite.

[0028] Introduction of disclosed technology Structural wood composites can be made from natural wood products such as veneers and strands. The properties of these structural composites depend largely on the properties of the materials used in such composites. Important engineering properties of structural wood products include flexural strength and flexural modulus. Numerous standardized test methods exist for evaluating the flexural strength and flexural modulus of structural wood products. Flexural strength values ​​are typically expressed as a modulus of rupture value, which reflects the influence of cross-sectional shape and size, as well as the inherent strength of the wood elements and adhesives, on the force required to fracture the member in a bending mode.

[0029] Veneer can be made by stripping logs and then soaking them in warm water to ensure the wood tissue is wet and soft. The wet logs are then cut into short segments called bolts (usually about 100 inches long). The bolts are then stripped on a lathe to produce strips of veneer, typically with thicknesses ranging from about 0.100 to 0.250 inches. The strips are then cut into strips (often about 100 inches parallel to the grain and about 50 inches perpendicular to the grain). The wet veneer strips are then dried and visually graded. In some cases, veneers can also be characterized for modulus using various nondestructive evaluation methods, such as X-ray and ultrasound. The resulting veneer can be used to manufacture plywood, LVL, PSL, or other veneer-based composite products.

[0030] Wood strands can be produced in a similar process that begins by debarking logs and then soaking them in warm water to ensure the wood tissue is wet and soft. The wet logs are cut into bolts and then processed in a strand processor. During this stage, the bolts are forced sideways against a series of rotating blades, cutting the bolts into thousands of strands. Ideally, each strand is approximately 2 to 6 inches long, approximately 0.5 to 2.0 inches wide, and approximately 0.015 to 0.50 inches thick. The grain direction of the wood in each strand is approximately parallel to the length axis of the strand. The strand mixture is dried and then sieved to remove small particles (dust and fines). These sieved strands can be used to produce OSB. Alternatively, strands approximately 6 to 15 inches long can be used to produce LSL. In some instances, strands approximately 8 feet long are cut from the veneer and then used to produce PSL.

[0031] It is known that the strength and modulus of these wooden elements are affected by the portion of the log used to obtain them. Specifically, logs originate from tree trunks. The strongest and hardest wood in a tree trunk is generally located at the base and outer layers of the trunk. Extracting wooden elements from portions of the trunk closer to the middle and / or top of the trunk results in wooden elements with lower strength and stiffness. Strength and stiffness can also be affected by the age of the tree at the time of harvest. Older trees tend to produce wooden elements with higher strength and stiffness. Interestingly, wood strength and stiffness can also be affected by the growth rate of the tree. Slower-growing trees tend to produce wooden elements with higher strength and stiffness. Of course, the type of wood species and subspecies can also affect wood strength and stiffness. The strength and stiffness of North American wood have both generally declined as planted trees and young forests become more common.

[0032] Based on the above information, it is clear that wood elements produced at a given manufacturing facility have a distribution of strength and stiffness properties. Traditionally, forest products companies have tended to source logs from forest areas located within approximately 200-400 miles of the manufacturing facility that converts the logs into products. Therefore, manufacturing facilities generally have a limited number of logs available per year (without incurring significant transportation costs). Furthermore, the available logs result in wood elements (veneer and / or strands) with a distribution of strength and stiffness values.

[0033] In some wood-based composite manufacturing facilities, the distribution of properties of the wood elements can prevent all of the wood elements from being used in the fabrication process. This can be particularly true for veneer-based composites, including LVL, which are commonly used in applications requiring relatively high bending strength and stiffness.

[0034] LVL is typically fabricated by applying a liquid phenolic bonding resin to one or both major surfaces of a veneer sheet using roll coating, spraying, flood coating, or other application methods. The bonded veneer sheets are then staggered into an essentially continuous mat running lengthwise. The grain direction of the veneer is also aligned lengthwise through the mat. The mat may contain approximately 6 to 16 layers of veneer at any given location, depending on the thickness of the veneer and the target thickness of the final LVL product. The mat is then placed in a hot press. The upper and lower platens of the press may have a temperature of approximately 330 to 400°F. The pressure applied to the mat may range from approximately 100 to 200 psi. Pressing times may range from approximately 200 to 700 seconds, depending on the target thickness of the final LVL product, platen temperature, and other parameters. The LVL emerges from the press as a continuous ribbon, which is then trimmed, cut to length, and split longitudinally depending on the intended application. A significant amount of LVL is used commercially as flange material for I-joists.

[0035] Wood I-joists are commonly used as horizontal members of subfloors in both residential and commercial structures. They offer a competitive alternative to solid-sawn lumber joists. I-joists are typically connected to rim boards along the perimeter of a building and span between foundation elements on the first floor. Alternatively, I-joists can span between walls on upper floors. I-joists are spaced approximately 16 to 24 inches apart and serve as the substrate and support for structural subfloor panels. Therefore, I-joists must be very stiff. In fact, I-joists are designed to be very stiff and lightweight.

[0036] I-joists are made by attaching flange elements to the top and bottom ends of a web element. The web element is often OSB, often 0.375 inches, 0.438 inches, or even 0.500 inches thick. The web height may range from approximately 6 to 14 inches. The web length may be approximately 8 to 60 feet. The flange elements can have widths ranging from approximately 1.375 to 2.25 inches. The flange element height may range from approximately 0.75 to 2.00 inches. The flange elements are commonly connected to the top and bottom ends of the web using profile joints and a structural adhesive (resorcinol-based or isocyanate). LVL is the preferred flange material for I-joists.

[0037] The stiffness of LVL has a dominant influence on the stiffness of I-joists. The stiffer the I-joist, the less floor movement and vibration (clay rattle) will occur when occupants walk across it in a residential or commercial building. The stiffer the I-joist, the greater the joist spacing in a floor system while maintaining the required structural integrity of the floor, thereby reducing construction costs. The stiffer the LVL, the lower the I-joist height, which helps reduce dead space between floors in a building and reduces overall construction costs. Therefore, there is a strong commercial incentive to utilize the stiffest plywood in the manufacture of LVL and I-joists.

[0038] For a given value of veneer thickness, the stiffness of the veneer is directly proportional to the modulus of the veneer. Therefore, the modulus value is an important indicator of the suitability of a given veneer sheet for LVL applications.

[0039] Unfortunately, in most cases, veneer produced at manufacturing sites contains a significant percentage of veneer with insufficient stiffness (or modulus) for LVL and I-joist applications. As an example, veneer produced at one manufacturing site had a stiffness of approximately 1.5 x 10 6 ~2.3×10 6 The modulus distribution has a standard deviation of approximately 2.0 x 10 5 psi is almost standard. In addition, the factory 6 Some factories build LVL requiring a modulus of about 1.8 x 10 psi. By intentionally building LVL using the stiffest veneer for the outermost layers and less stiff veneers for the middle layers, factories can achieve a modulus of about 1.8 x 10 psi. 6 ~2.3×10 6 Some veneers with modulus between 1.5 x 10 psi can be used. 6 ~1.8×10 6 The least stiff veneer, with a modulus of psi, is unsuitable for LVL production. In this example, the unusable veneer represents approximately 30.9% of the total veneer produced at the factory. As long as the veneer production costs are high and the market price of LVL is high, the modulus of the least stiff veneer can be reduced to approximately 2.0 x 10 6 There is a significant economic opportunity in improving this veneer to exceed this value.

[0040] Aspects of the Disclosed Technology Disclosed herein are methods for identifying properties of veneer and strand materials, as well as methods for improving the properties of lower grade veneer and strand materials. Also disclosed are examples of composites utilizing the improved veneer and strand materials.

[0041] There are several methods for quickly characterizing a veneer sheet with respect to bending modulus. In one example method 10 shown in Figure 1, the veneer is peeled and separated from the log or bolt. The peeled veneer is then cut, for example with a blade, into strips as shown.

[0042] The bending modulus of a piece of veneer produced in the manufacturing process can be measured nondestructively in the direction parallel to the grain. In one example of a method for nondestructively testing bending modulus values ​​in the direction parallel to the grain, the veneer is supported at two points by rolls, and the piece is processed so that a given veneer sheet spans the two rolls for a specific span length. A third roll can then be used to apply a vertical downward load to the veneer at a location equidistant between the two support rolls. The force applied by the third roll induces a moderate level of deflection in the veneer. In a continuous process, multiple sets of load-deflection data can be collected for each individual veneer sheet. The average load force, average deflection, span distance, and average thickness and width of the veneer can all be used to calculate a representative modulus value for the veneer sheet. In fact, a single veneer sheet can be characterized for bending modulus within 2-3 seconds using this method. In some instances, veneer sheets can be machine processed to measure the speed of sound propagation through the veneer. Particularly when ultrasonic information is combined with the density of the veneer, which can be determined automatically using an X-ray scanner, the speed of sound can be correlated with the bending modulus in a way that allows for reasonable predictions to be made.

[0043] With continued reference to FIG. 1 , after determining the bending modulus value of a veneer sheet, the veneer sheet can be immediately sorted based on whether the measured or estimated bending modulus value exceeds a predetermined threshold. In this manner, all of the veneer sheets produced on-site can be initially sorted into “pass” or “fail” groups. In some examples, the veneer sheets can be marked with a red or blue stripe or other visual marking system based on whether the measured bending modulus exceeds a predetermined threshold. The marked sheets can then be sorted into pass and fail groups later in the process. In some examples, only a portion of the veneer sheets produced on-site may be subjected to the bending modulus measurement and sorting process. In some examples, veneer with insufficient bending modulus may be shipped from multiple veneer fabrication plants to a conversion facility.

[0044] Veneers designated as having an insufficient flexural modulus can then be improved with a process that results in a flexural modulus value parallel to the grain that exceeds a predetermined threshold. The disclosed modification process can be carried out in multiple steps.

[0045] In the first step, the veneer pieces are modified by infiltrating the veneer with a filler solution. In some instances, the lignin in the veneer is partially degraded by the filler solution. This lignin degradation step facilitates subsequent compression of the veneer without disrupting cells or crushing the lignin. In some instances, the first step may also remove some of the lignin from the veneer. In other instances, the first step does not remove a significant amount of lignin from the veneer. In some instances, the filler solution includes water, and the veneer is heated to a temperature greater than about 50°C after treatment with the filler solution.

[0046] In the second step, the treated veneer is at least partially dried.

[0047] In the third step, the treated veneer is impregnated with a water-blocking agent. The dry weight of the impregnated water-blocking agent is about 1-50% of the dry weight of the veneer. Preferably, cells throughout the cross-section of the veneer absorb some amount of the water-blocking agent. Most preferably, cells throughout the cross-section of the veneer absorb a similar level of the water-blocking agent, with absorption occurring primarily in the amorphous cellulose and hemicellulose regions of the wood cell walls. The dry weight of the impregnated water-blocking agent may be about 1-20% of the dry weight of the wood.

[0048] In the fourth step, the treated veneer is partially dried a second time. In some instances, the treated veneer is gently dried in a manner that does not harden the water blocker.

[0049] In the fifth step, the treated veneer is maintained within a first temperature range of about 20-50°C and subjected to a sustained pressure of about 100-1,200 psi along an axis parallel to the thickness of the veneer until the density of the veneer increases to a first target density range. In some instances, the first target density range is about 900-1,100 kg / m without fully curing the waterproofing agent. 3 The moisture content of the compressed veneer may range from about 5 to 50%.

[0050] In a sixth step, the treated veneer is dried to reduce the moisture content to a second moisture content range of about 1-10%. In some instances, the treated veneer is dried without fully curing the water blocker.

[0051] In a seventh step, the treated wood is maintained within a second temperature range of about 20-150°C and sustained pressure is applied along an axis parallel to the thickness of the veneer until the density of the treated veneer increases to a second target density range. In some examples, the second target density range is about 950-1,400 kg / m. 3In some instances, the water blocker within the wood is fully cured upon reaching the second density range. Wood that has undergone all seven steps can be dimensionally stable and have a longitudinal flexural modulus in the range of about 6,000,000 to 8,000,000 psi (about 41 to 55 GPa).

[0052] In some instances, the water barrier within the cell walls of the treated wood can be cured after the fifth process step, thereby eliminating steps 6 and 7. This approach allows for a water resistance of approximately 900-1,250 kg / m 3 A dimensionally stable wood product can be obtained with a density value of about 25-40 GPa and a modulus of about 25-40 GPa. In this example, the temperature of the wood in the fifth step may be in the range of about 20-150°C.

[0053] In some instances, the third step can be omitted from the process, i.e., the waterproofing treatment can be omitted. In such instances, the partially dried veneer is dried a second time without being treated with a waterproofing agent.

[0054] Woods suitable for use as starting materials in the present disclosure include pine, poplar, fir, aspen, oak, maple, cherry, apple, balsa, linden, cedar, eucalyptus, etc. In some instances, grasses such as bamboo can be used in place of wood. In some instances, materials from various types of wood can be processed together.

[0055] The veneered wood pieces can have an initial thickness of less than about 0.25 inches. Wood pieces having a thickness of about 0.25 to 0.06 inches are preferred due to their ability to absorb aqueous filler solutions such as sodium hydroxide or other aqueous solutions, including aqueous solutions of water blockers, uniformly throughout the cross section of the wood during the first and third steps of the process.

[0056] The loading solution may contain chemicals known to degrade or otherwise modify lignin, so that the resulting treated wood can then be subjected to a loading of approximately 950 kg / m without disrupting the cells of the middle lamellae of the wood tissue or crushing the lignin. 3 The wood can be compressed to a level that achieves a density exceeding 100%. The filler solution can also promote rapid compression of the wood. The filler solution can include an aqueous sodium hydroxide solution. These solutions can be sodium hydroxide solutions with a concentration of about 0.1 to 15.0%. The filler solution can also include sodium sulfite and an oxidizing agent such as ozone, oxygen, hydrogen peroxide, and organic peroxides, or a combination thereof. The filler solution can also include an amine. Preferred amines include non-volatile low molecular weight amines such as ethanolamine, diethanolamine, triethanolamine, and hydroxylamine. The filler solution can be aqueous.

[0057] The veneer can be immersed in the filling solution. In some instances, the immersed veneer can be subjected to one or more vacuum cycles to promote absorption of the filling solution into the veneer. Specifically, the veneer piece can be placed in a rigid chamber along with the filling solution so that the veneer piece is immersed in the filling solution. A valve in the chamber can then be opened, and a portion of the air in the chamber's headspace can be removed from the chamber using a vacuum device. Under vacuum conditions, the air in the veneer piece is replaced with the aqueous filling solution at a rate faster than would be achieved without the vacuum. Additionally or alternatively, the immersed veneer can be subjected to a positive pressure, such as a pressure of 5 to 15 bar. Specifically, the veneer piece can be placed in a rigid chamber along with the filling solution so that the veneer piece is immersed in the filling solution. A valve in the chamber can then be opened, and additional air can be released into the chamber's headspace. Under positive pressure conditions, the aqueous filling solution is absorbed into the veneer piece at a rate faster than would be achieved without the positive pressure.

[0058] During the process of immersing the veneer in the aqueous filler solution, the moisture content of the veneer can be increased from a first moisture content of about 1-20% to a second moisture content of about 20-100% (dry basis moisture content). This process can be performed at temperatures between 20 and 200°C. The duration of the loading process can range from about 30 minutes to more than 12 hours, including durations of 60, 90, 120, 240, 360, 480, 600, 720, or more than 720 minutes. In some instances, these durations can be considered minimum exposure times (i.e., longer times can be used if desired). The required time depends on the dimensions of the veneer, the wood species, the composition of the filler solution, the temperature of the filler solution, and the use of vacuum and / or pressure. Generally, upon completion of this step, the active agent or agents in the filler solution should be distributed throughout the cross-section of the veneer. In some instances, the active agent or agent in the filler solution can be distributed throughout the cross section of the veneer in a relatively uniform manner. In some cases, the distribution of the filler solution within the veneer may not be uniform, but the distribution may be sufficient to achieve the desired effect of improving the compaction of the veneer in subsequent steps of the process.

[0059] After absorbing the filler solution, the treated veneer may be subjected to heat and pressure in a vessel, such as a pressure vessel. The temperature may range from about 20 to 200°C. The pressure may range from about 1 to 8 bar. Higher pressures may be required if the temperature is high enough to significantly increase water vapor pressure. For example, the filled veneer may be subjected to about 5 to 6 bar and a temperature of about 150 to 200°C for about 1 to 5 hours. Under these conditions, a reaction may occur between the active agent or agents in the filler solution and the lignin, causing the lignin to be partially decomposed or modified in a manner that promotes wood softening, especially at elevated temperatures. Partial decomposition generally involves reducing the molecular weight of the lignin, but not to the point where it becomes water-soluble. In some instances, the temperature of the filled wood can be adjusted to increase or decrease the amount of decomposed lignin in the wood to achieve a level beneficial for the subsequent compression step. The temperature values ​​associated with this process may range from about 60 to 200°C. In some instances, the activators or agents in the loading solution degrade or otherwise modify both the lignin and hemicellulose in the wood. The time required for this step can be empirically optimized by evaluating the compression rate in the subsequent compression step. After the desired level of modification is achieved, the veneer in the pressure vessel can be cooled to a temperature of about 20°C, and the pressure on the veneer can be reduced to about 1 bar. In some instances, the treated and conditioned veneer can be soaked or extracted in water to remove any lignin that has inadvertently been degraded to water solubility.

[0060] The moisture content of the treated veneer containing the modified lignin can then be reduced. In some instances, the moisture content of the treated veneer can be reduced to approximately 10-20% under mild drying conditions before subsequent processing steps. Drying can be achieved using a kiln or oven. Alternatively, drying can be achieved by placing the treated veneer in a chamber and subsequently reducing the pressure within the chamber. In some instances, the treated veneer can be immobilized in a manner that prevents dimensional distortion during the drying process. Partially drying the treated veneer can help promote absorption of water-blocking agents in subsequent processing steps.

[0061] Water blocking agents can include hydrophilic reactive monomers, hydrophobic reactive monomers, waxes, paper sizes, drying oils, topical sealants, coatings, and other materials that inhibit moisture absorption by the treated wood, or combinations thereof. A particularly advantageous class of water blocking agents is hydrophilic reactive monomers. One example of a class of hydrophilic reactive monomers is methylolated phenols. Another example of a class of hydrophilic reactive monomers is methylolated substituted phenols, such as methylolated cresols. One example of a class of hydrophobic reactive monomers is isocyanates.

[0062] The treated and impregnated veneer may then be subjected to a first compression step. In some examples, the treated and impregnated veneer may be loaded into a press, where the upper and lower platens of the press have a temperature in the range of about 20-150°C. The treated and impregnated veneer may be oriented in the press so that the thickness axis of the veneer is perpendicular to the contact surfaces of the platens. Pressure applied to the treated and impregnated veneer may be increased from 0 MPa to about 3-8 MPa over a period of 0-10 minutes. The applied pressure may then be maintained until the treated and impregnated veneer is compressed to about 40-50% of its original thickness. At this point, the density of the treated and impregnated veneer may be about 900-1,100 kg / m. 3This compression process can take approximately 5 to 100 minutes, depending on the original thickness of the treated and impregnated veneer, the applied pressure, the temperature of the platens, the wood species, and other factors, including those related to the first step of the process. The pressure applied to the treated and impregnated veneer is then released, after which the treated, impregnated, and compressed veneer can be removed from the press. In some instances, it can be beneficial to have the platen temperature in the range of approximately 20 to 60°C during the first compression step. Lower temperatures can help ensure that the absorbed water blocker does not harden during this step. Compression at such low temperatures can be facilitated by partially decomposing lignin (and / or hemicellulose) during the first stage of the fabrication process, which involves treating the veneer with the filler solution and subsequent heating.

[0063] The treated, impregnated, and compressed veneer pieces may then be subjected to a second drying step. In some instances, the treated, impregnated, and compressed veneer may be dried to a moisture content of about 1-10%. Drying may be accomplished using a kiln or oven. Alternatively, drying may be accomplished in a chamber operating under vacuum. In some instances, the treated, impregnated, and compressed veneer may be immobilized in a manner that prevents dimensional distortion (warping or twisting) during the drying process. Drying at low temperatures and under vacuum is preferred to prevent absorbed waterblocking agents from hardening during the drying process in this step.

[0064] The treated, impregnated, compressed, and dried veneer may then be subjected to a second compression step. The treated, impregnated, compressed, and dried veneer may be loaded into a press, where the upper and lower platens of the press have a temperature in the range of about 20-150°C. The veneer may be oriented in the press so that the thickness axis of the veneer is perpendicular to the contact surfaces of the platens. The pressure applied to the treated, impregnated, compressed, and dried veneer may be increased from 0 MPa to about 3-10 MPa over a period of 0-10 minutes. The applied pressure may then be increased so that the treated, impregnated, compressed, and dried veneer is compressed to about 1,100-1,400 kg / m. 3 In some instances, the density of the treated, impregnated, compressed and dried veneer is approximately 1,300 kg / m 3 In some instances, the density of the treated, impregnated, compressed and dried veneer can be increased to greater than about 1,350 kg / m 3 The pressure can be increased to values ​​greater than 1,200 kg / m. This second compression process can take approximately 2 to 40 minutes, depending on the original thickness of the veneer, the applied pressure, the temperature of the platen, the wood species, and other factors, including those related to the first step of the process. In some instances, after full compression of the veneer is achieved, the water-blocking agent in the treated, impregnated, and compressed veneer may be cured or otherwise converted to a polymerized state that is insoluble in water. The purpose of this technique is to cure the water-blocking agent after the treated, impregnated, compressed, and dried veneer has achieved its final compression goal. In some instances, the water-blocking agent can be cured before the pressure on the treated, impregnated, compressed, and dried veneer is relieved. In some instances, the water-blocking agent can be cured after the pressure on the treated, impregnated, compressed, and dried veneer is relieved. For example, the treated, impregnated, compressed, and dried veneer may be compressed to approximately 1,200 to 1,400 kg / m. 3The treated, impregnated, compressed, and dried veneer can be fully compressed to a density range of 1000 psi and then removed from the press and transferred to a kiln or oven to cure the imbibed waterproofing agent. In some instances, the treated, impregnated, compressed, and dried veneer can be immobilized within the kiln or oven to prevent the formation of geometric defects such as twisting or warping.

[0065] Treated, impregnated, and compressed veneers produced according to the present disclosure may exhibit improved dimensional stability when exposed to water. The amount of swelling along the thickness axis can be significantly reduced using a water blocker. In some instances, the amount of swelling along the thickness axis can be less than about 5% using a water blocker.

[0066] Thus, veneer products and veneer-based strand products produced according to the methods disclosed herein can achieve a non-normal distribution of properties (i.e., a truncated distribution), with low value outliers being avoided by use of the methods disclosed herein.

[0067] As a result, veneer products and veneer-based strand products produced according to the methods disclosed herein can meet or exceed target properties. In some examples, the average bending modulus in the direction parallel to the grain of the veneer products and veneer-based strand products can be at least 1.8×10 6 psi, at least 2.0 x 10 6 psi, at least 2.2 x 10 6 psi, or at least 2.4 x 10 6 In some examples, the minimum bending modulus parallel to the grain of the veneer product and the veneer-based strand product may be at least 1.8×10 psi. 6 psi, at least 2.0 x 10 6 psi, at least 2.2 x 10 6 psi, or at least 2.4 x 10 6 In some examples, the average density of the veneer product and the veneer-based strand product may be at least 800 kg / m3 , at least 1,000 kg / m 3 , at least 1,200 kg / m 3 , or at least 1,400 kg / m 3 In some examples, the minimum density of the veneer product and the veneer-based strand product may be at least 800 kg / m 3 , at least 1,000 kg / m 3 , at least 1,200 kg / m 3 , or at least 1,400 kg / m 3 It could be.

[0068] According to some aspects of the present disclosure, veneer products produced according to the methods disclosed herein can be used in a variety of products. In some examples, the product can be a composite including one or more veneer layers produced according to the methods disclosed herein. In some examples, the product can be a plywood product including two or more veneer layers produced according to the methods disclosed herein. In some examples, the product can be an I-joist having a central web section and outer upper and lower flange sections. In such examples, the flange sections can include a veneer layer produced according to the methods disclosed herein.

[0069] According to some aspects of the present disclosure, the improved veneer-based strands produced according to the methods disclosed herein can be used in a variety of products. In some examples, the product may be an oriented strand board product comprising veneer-based strands produced according to the methods disclosed herein. In some examples, the product may be a parallel strand lumber product comprising veneer-based strands produced according to the methods disclosed herein. In some examples, the product may be a laminated strand lumber product comprising veneer-based strands produced according to the methods disclosed herein. [Example]

[0070] Examples of the disclosed technology In a comparative example, the longitudinal flexural modulus was measured on eight small samples of natural tulip tree veneer. See Table 1. Similarly, four small samples of tulip tree veneer from the same population as the control group were subjected to the veneer modification process of the present disclosure and then measured for longitudinal flexural modulus. See Table 2. Flexural modulus values ​​were determined using the ASTM D1037 method. [Table 1] [Table 2]

[0071] Assuming that the flexural modulus values ​​for the natural tulip tree population are normally distributed, it is possible to calculate, based on the data shown in Table 1, that 78.2% of the veneer samples from the natural tulip tree population have flexural modulus values ​​less than 1,800,000 psi.

[0072] In contrast, based on the data shown in Table 2, it is calculated that nearly 0.0% of the veneer samples in the modified tulipwood population had flexural modulus values ​​less than 1,800,000 psi. Therefore, if the flexural modulus value required for veneers for LVL applications was 1,800,000 psi, all of the veneers in this modified group would be suitable for structural LVL applications.

[0073] In some examples of the present disclosure, wood elements, such as sliced ​​wood, strands, slats, particles, fibers, or other wood elements, may be subjected to the processes described herein. In this manner, a population of different types of wood elements having initial bending modulus properties, where some of the population have unacceptable bending modulus values ​​and other portions of the population have acceptable bending modulus values, may be subjected to a process that effectively converts the entire population so that all of the wood elements have acceptable bending modulus values.

[0074] Additional examples of disclosed technologies In view of the above-described embodiments of the disclosed subject matter, the present application discloses the following additional examples: It should be noted that any feature of an example taken alone or in combination with one or more features of an example, and optionally in combination with one or more features of one or more additional examples, are additional examples that are also included within the disclosure of the present application.

[0075] Example 1 1. A method comprising the steps of: subjecting a series of wood veneer pieces to non-destructive parallel-to-grain bending modulus measurements; sorting the veneer pieces into a first group having modulus values ​​above a predetermined threshold and a second group having modulus values ​​below the threshold; and subjecting the veneer pieces in the second group to a process that increases the parallel-to-grain bending modulus values ​​above the predetermined threshold.

[0076] Example 2 The method of any example herein, particularly Example 1, wherein the process of increasing the bending modulus value parallel to the grain comprises a lignin degradation step and a compression step.

[0077] Example 3 The method of any embodiment herein, particularly Example 1, wherein the process used to increase the bending modulus value parallel to the grain comprises: impregnating the veneer with a filler solution to produce a treated veneer; impregnating the treated veneer with a water blocker; compressing the treated veneer along a thickness axis until the density of the treated veneer is in a first density range; reducing the moisture content of the treated veneer to a range of about 1-10%; and compressing the treated veneer along a thickness axis until the density of the treated veneer is in a second density range.

[0078] Example 4 The method of any example herein, especially Example 3, wherein the loading solution is sodium hydroxide, sodium sulfite, or a combination thereof.

[0079] Example 5 The method of any example herein, especially Example 3, wherein the loading solution is a non-volatile amine, including ethanolamine, diethanolamine, triethanolamine, and hydroxylamine, or a combination thereof.

[0080] Example 6 The method of any example herein, especially Example 3, wherein the water blocking agent is a hydrophilic reactive monomer comprising methylolated phenol, methylolated substituted phenol including methylolated cresol, or a combination thereof.

[0081] Example 7 The method of any example herein, especially Example 3, wherein the water blocking agent is an isocyanate.

[0082] Example 8 The first density range is approximately 900 to 1,200 kg / m 3 The method of any example herein, particularly Example 3, wherein

[0083] Example 9 The second density range is approximately 1,200 to 1,400 kg / m 3 The method of any example herein, particularly Example 3, wherein

[0084] Example 10 The method of any embodiment herein, particularly Example 3, wherein the treated veneer has a bending modulus parallel to the grain in the long axis of about 14 to 50 GPa.

[0085] Example 11 The method of any embodiment herein, particularly Example 1, wherein the process used to increase the bending modulus value parallel to the grain comprises: infiltrating the veneer with a filler solution to form a treated veneer; reducing the moisture content of the treated veneer to a range of about 1-20%; and compressing the treated veneer along its thickness axis until the density of the treated veneer is in a target density range.

[0086] Example 12 The method of any example herein, especially Example 11, wherein the loading solution is sodium hydroxide, sodium sulfite, or a combination thereof.

[0087] Example 13 The method of any example herein, especially Example 11, wherein the loading solution is a non-volatile amine, including ethanolamine, diethanolamine, triethanolamine, hydroxylamine, or a combination thereof.

[0088] Example 14 Target density range: approximately 800 to 1,400 kg / m 3 The method of any example herein, particularly Example 11, wherein

[0089] Example 15 The method of any example herein, particularly Example 11, wherein the treated veneer has a bending modulus parallel to the grain in the long axis of about 14 to 50 GPa.

[0090] Example 16 The threshold is about 1.8 × 10 6 The method of any of the Examples herein, particularly Example 1, wherein the .alpha.-methyl-.beta ...

[0091] Example 17 The threshold is approximately 2.0 × 10 6 The method of any of the Examples herein, particularly Example 1, wherein the .alpha.-methyl-.beta ...

[0092] Example 18 The threshold is about 2.2 × 10 6 The method of any of the Examples herein, particularly Example 1, wherein the .alpha.-methyl-.beta ...

[0093] Example 19 The threshold is about 2.4 × 10 6 The method of any of the Examples herein, particularly Example 1, wherein the .alpha.-methyl-.beta ...

[0094] Example 20 A composite comprising a material produced by the method of any example herein, particularly Example 1.

[0095] Example 21 1. A product comprising two or more veneer layers, wherein one or more of the veneer layers are obtained from a conventional veneer manufacturing process; and wherein one or more of the veneer layers are the product of a process used to increase the bending modulus value of the veneer layer in a direction parallel to the grain, the process including a lignin degradation step and a compression step.

[0096] Example 22 An I-joist having a central web section and outer upper and lower flange sections, the flange sections being constructed from laminated veneer lumber, and one or more veneer layers most distal to the web being the product of a process used to increase the bending modulus value in a direction parallel to the grain of the one or more veneer layers, including a lignin decomposition step and a compression step.

[0097] Example 23 A composite comprising two or more veneer layers, all of which are the product of a process that includes a lignin degradation step and a compression step used to increase the flexural modulus value of the veneer layers in a direction parallel to the grain.

[0098] Example 24 All plywood sheets in the group are 1.8 x 10 6 A system comprising a population of veneer sheets having a non-normal truncated distribution of flexural modulus values, such that the veneer sheets have flexural modulus values ​​above a predetermined flexural modulus threshold in psi.

[0099] Example 25 1. A plywood product comprising two or more veneer layers, wherein at least one of the veneer layers is obtained from a conventional veneer manufacturing process; and wherein at least one of the veneer layers is the product of a process used to increase the bending modulus value of the veneer layer in a direction parallel to the grain, the process comprising a lignin degradation step and a compression step.

[0100] Example 26 1. A plywood product comprising a plurality of veneer layers, all of which are the product of a process that includes a lignin degradation step and a compression step used to increase the bending modulus value of the veneer layer in a direction parallel to the grain.

[0101] Example 25 1. An article of manufacture comprising a plurality of veneer-based strands, wherein at least 1% by weight of the veneer-based strands are obtained from a conventional veneer manufacturing process; and wherein at least 1% by weight of the veneer-based strands are a product of a process used to increase the bending modulus value of the veneer-based strands in a direction parallel to the grain.

[0102] Example 28 A parallel strand lumber product comprising a plurality of veneer-based strands, all of which are the product of a process that includes a lignin degradation step and a compression step used to increase the bending modulus value of the veneer-based strands in a direction parallel to the grain.

[0103] Example 29 A laminated strand lumber product comprising a plurality of strands, wherein at least 1% by weight of the strands are obtained from a conventional strand manufacturing process; and at least 1% by weight of the strands are the product of a process used to increase the bend value of the strands in a direction parallel to the grain, the process including a lignin degradation step and a compression step.

[0104] Example 30 A laminated strand lumber product comprising a plurality of strands, all of which are the product of a process that includes a lignin degradation step and a compression step used to increase the bending modulus value of the strands in a direction parallel to the grain.

[0105] Example 31 An oriented strand board product comprising a plurality of strands, wherein at least 1% by weight of the strands are obtained from a conventional strand manufacturing process; and at least 1% by weight of the strands are the product of a process used to increase the bending modulus value of the strands in a direction parallel to the grain, the process including a lignin degradation step and a compression step.

[0106] Example 32 An oriented strand board product comprising a plurality of strands, all of which are the product of a process that includes a lignin degradation step and a compression step used to increase the bending modulus value of the strands in a direction parallel to the grain.

[0107] Example 33 A method of construction in which a composite product is used; the composite product includes a veneer that is the product of a process used to increase the bending modulus value of the veneer in a direction parallel to the grain, the process including a lignin degradation step and a compression step; and the composite product enables the use of increased spacing between structural members in buildings.

[0108] Example 34 A method of construction in which a composite product is used; the composite product comprising veneer that is the product of a process used to increase the bending modulus value in a direction parallel to the grain of the veneer, including a lignin degradation step and a compression step, the composite product allowing for the use of reduced floor thickness in buildings.

[0109] Example 35 1. A method for improving the mechanical properties of wood veneer, comprising the steps of: impregnating wood veneer with a filler solution to produce a treated veneer; partially drying the treated veneer a first time; impregnating the treated veneer with a water-blocking agent; partially drying the treated veneer a second time; and improving the density of the treated veneer to 900-1,100 kg / m without fully curing the water-blocking agent. 3 holding the treated veneer at a temperature in the range of 20-50°C and a pressure in the range of 100-1200 psi until the moisture content is in the range of between 1% and 10%.

[0110] In view of the many possible ways in which the principles of this disclosure may be applied, it is recognized that the described arrangements represent examples of the disclosed technology and should not be construed as limiting the scope of the disclosure and the claims that follow. Rather, the scope of claimed subject matter is defined by the following claims and their equivalents.

Claims

1. subjecting a series of wood veneer pieces to non-destructive parallel-to-grain bending modulus measurements; sorting the veneer pieces into a first group including the veneer pieces having a coefficient value above a predetermined threshold and a second group including the veneer pieces having a coefficient value below the threshold; subjecting the second group of veneer pieces to a process that increases the bending modulus value parallel to the grain to a value above the predetermined threshold; A method comprising:

2. 10. The method of claim 1, wherein the process of increasing the bending modulus value parallel to the grain comprises a lignin degradation step and a compression step.

3. The process used to increase the bending modulus value parallel to the grain is infiltrating the veneer with a filling solution to produce a treated veneer; impregnating the treated veneer with a waterproofing agent; compressing the treated veneer along a thickness axis until the density of the treated veneer is within a first density range; reducing the moisture content of the treated veneer to a range of about 1-10%; compressing the treated veneer along the thickness axis until the density of the treated veneer is in a second density range; The method of claim 1 , comprising:

4. The method of claim 3 , wherein the loading solution is sodium hydroxide, sodium sulfite, or a combination thereof.

5. 4. The method of claim 3, wherein the loading solution is a non-volatile amine, including ethanolamine, diethanolamine, triethanolamine, and hydroxylamine, or a combination thereof.

6. 4. The method of claim 3, wherein the water blocking agent is a hydrophilic reactive monomer comprising methylolated phenol, methylolated substituted phenol including methylolated cresol, or a combination thereof.

7. The method of claim 3 wherein the water blocking agent is an isocyanate.

8. The first density range is about 900 to 1,200 kg / m ３ The method of claim 3, wherein

9. the second density range is about 1,200 to 1,400 kg / m ３ The method of claim 3, wherein

10. 4. The method of claim 3, wherein the treated veneer has a bending modulus parallel to the grain in its long axis of about 14 to 50 GPa.

11. The process used to increase the bending modulus value parallel to the grain is infiltrating the veneer with a filling solution to form a treated veneer; reducing the moisture content of the treated veneer to a range of about 1-20%; compressing the treated veneer along a thickness axis until the density of the treated veneer is within a target density range; The method of claim 1 , comprising:

12. 12. The method of claim 11, wherein the loading solution is sodium hydroxide, sodium sulfite, or a combination thereof.

13. 12. The method of claim 11, wherein the loading solution is a non-volatile amine comprising ethanolamine, diethanolamine, triethanolamine, hydroxylamine, or a combination thereof.

14. The target density range is about 800 to 1,400 kg / m ３ The method of claim 11, wherein

15. 12. The method of claim 11, wherein the treated veneer has a flexural modulus parallel to the grain in its long axis of about 14 to 50 GPa.

16. The threshold is about 1.8×10 ６ 10. The method of claim 1, wherein the pressure is greater than 100 psi.

17. The threshold is about 2.0×10 ６ 10. The method of claim 1, wherein the pressure is greater than 100 psi.

18. The threshold is about 2.2×10 ６ 10. The method of claim 1, wherein the pressure is greater than 100 psi.

19. The threshold is about 2.4×10 ６ 10. The method of claim 1, wherein the pressure is greater than 100 psi.

20. 1. A method for improving the mechanical properties of wood veneers, comprising: impregnating the wood veneer with a filling solution to produce a treated veneer; Partially drying the treated veneer for a first time; impregnating the treated veneer with a waterproofing agent; Partially drying the treated veneer a second time; The density of the treated veneer is 900 to 1,100 kg / m without completely hardening the waterproofing agent. ３ holding the treated veneer at a temperature in the range of 20-50°C and a pressure in the range of 100-1200 psi until the treated veneer reaches a temperature in the range of drying the treated veneer until the moisture content is in the range of between 1% and 10%; A method comprising:

21. 21. An article of manufacture comprising two or more veneer layers, wherein one or more of said veneer layers are obtained from a conventional veneer making process; and wherein one or more of said veneer layers is the product of a method according to any one of claims 1 to 20.

22. 22. An I-joist having a central web section and outer upper and lower flange sections, the flange sections being constructed from laminated veneer lumber, and one or more veneer layers most distal to the web section being the product of a method described in any one of claims 1 to 21.

23. 22. A product comprising two or more veneer layers, all of said veneer layers being the product of the method of any one of claims 1 to 21.

24. All plywood sheets in the group are 1.8 x 10 ６ A system comprising said population of veneer sheets having a non-normal cut distribution of flexural modulus values, such that said veneer sheets have flexural modulus values ​​above a predetermined flexural modulus threshold in psi.

25. 22. An article of manufacture comprising a plurality of veneer-based strands, wherein at least 1% by weight of the veneer-based strands are obtained from a conventional veneer-making process; and wherein at least 1% by weight of the veneer-based strands are a product of the method of any one of claims 1 to 21.

26. 22. An article of manufacture comprising a plurality of strands of veneer base, all of said strands of veneer base being the product of the method of any one of claims 1 to 21.

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