阅读说明：本技术 木材复合面板产品的木质素强化粘附性 (Lignin enhanced adhesion for wood composite panel products ) 是由 章耀林 L·库伊斯奈 M·帕列奥洛古 S·帕拉迪斯-博伊斯 S·雷蒙德 M·W·冯 Z· 于 2018-10-02 设计创作，主要内容包括：提供了一种用木质素改性木质纤维素材料并且将木质素和异氰酸酯或其他木材胶粘剂掺入木材产品组合物中的方法,并且公开了其组合物、制备和用于结合木材产品的应用。所述组合物包含衍生自多种天然资源的木质素、含有两个或更多个异氰酸酯官能团的异氰酸酯化合物、或其他木材胶粘剂。(A method of modifying lignocellulosic material with lignin and incorporating lignin and isocyanates or other wood adhesives into wood product compositions is provided, as well as compositions, preparations, and uses thereof for bonding wood products. The compositions include lignin derived from a variety of natural sources, isocyanate compounds containing two or more isocyanate functional groups, or other wood adhesives.)

1. A method of producing a wood product, comprising:

a) blending wood material with lignin, isocyanate or other adhesive and a portion of wax or no wax to produce a resinated material;

b) forming a pad from the resinated material; and

c) the mat is compressed or molded at elevated temperatures to produce a wood product.

2. The method of claim 1, wherein the wood material and lignin are first blended in a blender to produce a wood material-lignin mixture; flowing the wood material-lignin mixture into a digester, compressing the wood material-lignin mixture; steaming the compressed wood material-lignin mixture by injecting pressure steam; refining the compressed wood material-lignin mixture to produce refined fibers; and blending the refined fibers with an isocyanate and a portion of the wax or no wax to produce the resinated material.

3. The method of claim 1, comprising incorporating the lignin into the wood material by a plug screw, producing a wood material-lignin mixture; flowing the wood material-lignin mixture into a digester, compressing the wood material-lignin mixture; steaming the compressed wood material-lignin mixture by injecting pressure steam; refining the compressed wood material-lignin mixture to produce refined fibers; and blending the refined fibers with an isocyanate and a portion of the wax or no wax to produce the resinated material.

4. The method of claim 1, wherein flowing the wood material through a plug screw compresses the wood material; flowing the compressed wood material into a digester, wherein the lignin is incorporated, producing a compressed wood material-lignin mixture; steaming the compressed wood material-lignin mixture by injecting pressure steam; refining the compressed wood material-lignin mixture to produce refined fibers; and blending the refined fibers with an isocyanate and a portion of the wax or no wax to produce the resinated material.

5. The method of claim 1, wherein flowing the wood material through a plug screw compresses the wood material; flowing the compressed wood material into a digester; steaming the compressed wood material by injecting pressure steam; incorporating the lignin into the compressed wood material, producing a compressed wood material-lignin mixture; refining the compressed wood material-lignin mixture to produce refined fibers; and blending the refined fibers with an isocyanate and a portion of the wax or no wax to produce the resinated material.

6. The method of claim 1, wherein flowing the wood material through a plug screw compresses the wood material; flowing the compressed wood material into a digester; steaming the compressed wood material by injecting pressure steam; refining the compressed wood material to produce refined fibers; incorporating the lignin into the refined fiber through a blowing line to produce a refined fiber-lignin mixture, blending the refined fiber-lignin mixture with an isocyanate and a portion of the wax or no wax to produce the resinated material.

7. The method of claim 1, wherein flowing the wood material through a plug screw compresses the wood material; flowing the compressed wood material into a digester; steaming the compressed wood material by injecting pressure steam; refining the compressed wood material to produce refined fibers; blending the refined fiber into the isocyanate and a portion of the wax or no wax, resulting in a refined fiber-isocyanate mixture; drying the refined fiber-isocyanate mixture; and blending lignin into the refined fiber-isocyanate mixture to produce the resinated material.

8. The method of any one of claims 2-7, wherein the pressure steam has a temperature between 130 ℃ and 190 ℃.

9. The method according to any one of claims 2-8, wherein the wood material is wood chips or wood sawdust.

10. The method according to any one of claims 1-9, wherein the wood product is an insulation board and/or a molded product.

11. The method according to any one of claims 2-9, wherein the wood product is a low density insulation board, a Medium Density Fiberboard (MDF), a High Density Fiberboard (HDF), a fiber-based insulation board, a paper product, or a non-wood lignocellulosic board.

12. The method of claim 1, wherein the wood product is Particle Board (PB), Oriented Strand Board (OSB), bark board, or non-wood lignocellulosic board.

13. The method of any one of claims 1-12, wherein the lignin is in the form of a powder or in suspension.

14. The method of any one of claims 1-13, wherein the lignin is kraft lignin, soda lignin, hydrolyzed lignin, lignosulfonate, organosolv lignin, dioxane acid hydrolyzed lignin, milled wood lignin, or krasone lignin.

15. The method of claim 1, wherein the wood material is in the form of wood particles and the wood adhesive is a urea-formaldehyde resin or a phenol-formaldehyde resin or an isocyanate resin to produce particle board.

16. The method of claim 1, wherein the wood material is in the form of wood strands, wherein the individual strands are about 2.0-2.5cm x 10-15cm, and the wood adhesive is a phenol-formaldehyde resin or an isocyanate resin to produce an OSB panel.

17. A method of producing a wood product, comprising:

a) blending wood chips with lignin in a blender to produce a wood chip-lignin mixture;

b) flowing the wood chip-lignin mixture through a plug screw, compressing the wood chip-lignin mixture;

c) flowing the compressed wood chip-lignin mixture into a digester;

d) steaming the compressed wood chip-lignin mixture by injecting pressure steam;

e) refining the compressed wood chips-lignin mixture to produce refined fibers;

f) adding isocyanate and a portion of wax or no wax to the refined fiber to produce an isocyanate-refined fiber mixture;

g) drying the isocyanate-refined fiber mixture to produce a dry resinated fiber;

h) forming a mat from the dry resinated fibers; and

i) compressing or molding the mat to produce the wood product.

18. A method of producing a wood product, comprising:

a) blending wood chips with lignin;

b) flowing the wood chips and lignin mixture through a plug screw and compressing the wood chips and lignin, producing a compressed wood chips-lignin mixture;

c) flowing the compressed wood chip-lignin mixture into a digester;

d) steaming the compressed wood chip-lignin mixture by injecting pressure steam;

e) refining the compressed wood chips-lignin mixture to produce refined fibers;

f) adding isocyanate and a portion of wax or no wax to the refined fiber to produce an isocyanate-refined fiber mixture;

g) drying the isocyanate-refined fiber mixture to produce a dry resinated fiber;

h) forming a mat from the dry resinated fibers; and

i) compressing or molding the mat to produce the wood product.

19. A method of producing a wood product, comprising:

a) blending wood chips;

b) flowing the wood chips through a plug screw and compressing the wood chips;

c) flowing the compressed wood chips into a digester, wherein the lignin is incorporated, producing a compressed wood chip-lignin mixture;

d) steaming the compressed wood chip-lignin mixture by injecting pressure steam;

e) refining the compressed wood chips-lignin mixture to produce refined fibers;

f) adding isocyanate and a portion of wax or no wax to the refined fiber to produce an isocyanate-refined fiber mixture;

g) drying the isocyanate-refined fiber mixture to produce a dry resinated fiber;

h) forming a mat from the dry resinated fibers; and

i) compressing or molding the mat to produce the wood product.

20. A method of producing a wood product, comprising:

a) blending wood chips;

b) flowing the wood chips through a plug screw and compressing the wood chips;

c) flowing the compressed wood chips into a digester;

d) (ii) steaming the compressed wood chips by injection of pressure steam and subsequently incorporating the lignin into the compressed wood chips, producing a wood chips-lignin mixture;

e) refining the compressed wood chips-lignin mixture to produce refined fibers;

f) adding isocyanate and a portion of wax or no wax to the refined fiber to produce an isocyanate-refined fiber mixture;

g) drying the isocyanate-refined fiber mixture to produce a dry resinated fiber;

h) forming a mat from the dry resinated fibers; and

i) compressing or molding the mat to produce the wood product.

21. A method of producing a wood product, comprising:

a) blending wood chips;

b) flowing the wood chips through a plug screw and compressing the wood chips;

c) flowing the compressed wood chips into a digester;

d) steaming the compressed wood chips by injecting pressure steam;

e) refining the compressed wood chips to produce refined fibers;

f) incorporating the lignin into the refined fiber through a blowing line to produce a refined fiber-lignin mixture;

g) adding isocyanate and a portion of wax or no wax to the refined fiber-lignin mixture to produce an isocyanate-refined fiber mixture;

h) drying the isocyanate-refined fiber mixture to produce a dry resinated fiber;

i) forming a mat from the dry resinated fibers; and

j) compressing or molding the mat to produce the wood product.

22. A method of producing a wood product, comprising:

a) blending wood chips;

b) flowing the wood chips through a plug screw and compressing the wood chips;

c) flowing the compressed wood chips into a digester;

d) steaming the compressed wood chips by injecting pressure steam;

e) refining the compressed wood chips to produce refined fibers;

f) adding isocyanate and a portion of wax or no wax to the refined fiber to produce an isocyanate-refined fiber mixture;

g) drying the isocyanate-refined fiber mixture to produce a dry resinated fiber;

h) blending lignin into the dry resinated fibers, producing a resinated material;

i) forming a mat from the dry resinated material; and

j) compressing or molding the mat to produce the wood product.

23. The method of any one of claims 17-22, wherein the pressure steam has a temperature between 130 ℃ and 190 ℃.

24. A method according to any one of claims 17 to 22, wherein the wood product is an insulation board and or a moulded product.

25. The method of any one of claims 17-22, wherein the wood product is a low density insulation board, a Medium Density Fiberboard (MDF), a High Density Fiberboard (HDF), a fiber-based insulation board, a paper product, a Particle Board (PB), an Oriented Strand Board (OSB), a bark board, or a non-wood lignocellulosic board.

26. The method of any one of claims 17-22, wherein the lignin is in the form of a powder or in suspension.

27. The method of any one of claims 17-26, wherein the lignin is kraft lignin, soda lignin, hydrolyzed lignin, lignosulfonate, organosolv lignin, dioxane acid hydrolyzed lignin, milled wood lignin, or krasone lignin.

28. A lignocellulosic material produced by the method as defined in any one of claims 1-27.

29. The lignocellulosic material of claim 28, wherein the lignocellulosic material is insulation board and/or a molded product.

30. The lignocellulosic material of claim 29, wherein the lignocellulosic material is a low density insulation board, a Medium Density Fiberboard (MDF), a High Density Fiberboard (HDF), a fiber-based insulation board, a paper product, a Particle Board (PB), an Oriented Strand Board (OSB), a bark board, or a non-wood lignocellulosic board.

Technical Field

Which is a method of modifying lignocellulosic materials with lignin and incorporating lignin and isocyanate wood adhesives into wood product compositions.

Background

The most common wood composite panel products include plywood, Oriented Strand Board (OSB), Particle Board (PB), and fiberboard of varying densities [ low density fiberboard (L DF), Medium Density Fiberboard (MDF), and High Density Fiberboard (HDF) ]. the major wood adhesives currently used are formaldehyde-based resins such as urea-formaldehyde (UF), melamine-formaldehyde (MF), melamine-urea-formaldehyde (MUF) resorcinol-formaldehyde (RF), phenol-resorcinol-formaldehyde (PRF), and phenol-formaldehyde (PF) resins, and formaldehyde-free resins such as the polymer methylene diphenyl diisocyanate (pMDI) ]. formaldehyde-based resins for wood applications are thermosetting resins.

Resin systems used in most wood composite panel products (e.g., OSB, PB, and MDF) typically include a resin (e.g., UF, PF, pMDI, etc.) and a wax. The role of wax in wood composites is to reduce the water absorption of wood composite panels and improve dimensional stability. However, wax does not contribute to bonding. Conversely, if it is present between the wood furnish particles, it weakens the bond. Each type of wood composite panel has different requirements on the resin applied. For OSB panel manufacture, the resin viscosity should be below 500cps, typically 150-300 cps. For the manufacture of PB boards and MDF boards, the resin viscosity should be less than 1000 cps. If the resin viscosity is high, some measures need to be taken to adjust the resin application system to ensure that the resin application is uniform and well distributed over the surface of the wood furnish.

Wood consists of three main components: cellulose (about 40% -50%), hemicellulose (about 20% -30%) and lignin (about 20% -30%). Lignin is a very important component of all lignocellulosic materials, including wood. As a macromolecule, lignin is a polyphenol and amorphous, contributing greatly to the natural properties of wood. Conceivably, wood properties could be significantly altered or enhanced if additional lignin content could be introduced into the wood, which would lead to new or improved wood products and various economic and environmental benefits.

Several assumptions can be made about how lignin can enhance the adhesion of wood composite panels: 1) lignin incorporated into such products helps create strong physical interactions between the lignocellulosic materials during the heat treatment step of the panel manufacturing process, resulting in adhesion between the lignocellulosic materials, and 2) lignin associates with different resin systems (e.g., isocyanates, phenolic resins, and/or urea-formaldehyde resins and waxes) via different mechanisms (e.g., chemical reactions) to enhance adhesion between the lignocellulosic materials.

The first assumption described above can be demonstrated based on the following. Typically, during the manufacture of wood composite panels, the moisture content of the resinated lignocellulosic material (wood furnish) is about 6-15%, preferably 8-12%. Further, the pressing temperature is about 180 ℃ to 225 ℃. When additional lignin is incorporated into the lignocellulosic material at a dosage of about 0 wt% to 10 wt% or preferably 0.25 wt% to 3 wt% based on dry wood weight, this lignin is expected to associate with water molecules (e.g., through hydration or hydrogen bonding of ionic groups) to form certain lignin-water complexes. As is known in the art, the glass transition temperature of softwood lignin is about 140 ℃ to 170 ℃ when in dry form, while the glass transition temperature of hardwood lignin is about 110 ℃ to 140 ℃ when in dry form. The glass transition temperature, Tg, is the temperature at which the polymer changes from a rigid plastic (below Tg) to a flexible rubbery material (above Tg). As is also known, when lignin is in wet form and/or other wood components (e.g., cellulose, hemicellulose) are present, the glass transition temperature is significantly reduced by up to 100 ℃. Thus, by this mechanism (concurrent softening of the added lignin and lignin in the lignocellulosic material), it is expected that during the manufacturing of the wood composite, the added lignin can establish strong physical interactions with the lignin in the lignocellulosic material, since the latter is constituted by about 20-30 wt% of lignin. As a result, strong adhesion is expected to form between the lignocellulosic material and the lignin during panel manufacturing because the temperature to which the wet lignin is exposed is in the same range as the glass transition temperature of the wet lignin (platen temperature may be greater than 180 ℃, while the core temperature of the lignocellulosic material is typically higher than 130 ℃ or 140 ℃). After the panel cools, it is expected that the lignin solidifies (in the form of a rigid plastic), creating permanent adhesion between the lignocellulosic materials (e.g., wood particles used).

The second assumption above can be demonstrated based on the following. Depending on the resin system used (e.g. isocyanate resins, phenolic resins, urea-formaldehyde resins and waxes), lignin will enhance the adhesion between lignocellulosic materials by different mechanisms. For example, the case of three different resin systems is discussed below.

A) Isocyanate resin System (typically pMDI waxed)

When isocyanates, particularly pMDI (NCO content of about 30% by weight), are used in the manufacture of lignocellulosic material panels, the dosage of pMDI is less than 5 wt% and most typically 2 wt% to 3 wt% based on the dry weight of the lignocellulosic material. If, for example, in such an adhesive system, it has 3 wt% lignin, 3 wt% pMDI and 8 wt% moisture (based on the dry weight of the lignocellulosic material before pressing), the weight ratio of lignin, pMDI and water will be 3: 8. The molar ratio of functional groups will be different from the weight ratio. The hydroxyl content of lignin is typically between 200 and 300 mgKOH/g. This means that 100g of lignin contains 0.356 to 0.534 moles of hydroxyl groups which can react with NCO groups in the isocyanate. pMDI typically contains 30 wt% NCO content, yielding 0.714 mole NCO groups in 100g of pMDI. The hydroxyl content in 100g of water will be 11.11 moles. Thus, in the case of a weight ratio of lignin to pMDI to water of 3: 8, the ratio of OH in lignin to NCO groups in pMDI to OH groups in water will be 0.356-0.534: 0.714 to (11.11X 8/3): 0.356-0.534: 0.714: 29.629 ═ 1.0-1.5: 2.0: 83. As seen from these relative molar ratios, the-OH (hydroxyl) groups in water are much higher than the-OH groups in lignin. The relative reactivity of the isocyanate with "OH" groups at 25 ℃ under non-catalytic conditions is as follows: for primary hydroxyl (RCH)₂-OH) is 100, for water (HOH) is 100, for carboxylic hydroxyl (RCOOH) is 40, for secondary hydroxyl (RR 'CH-OH) is 30, and for tertiary hydroxyl (RR' R "C-OH) is 0.5. The relative reactivity of the isocyanates with amines and derivatives is as follows: for primary aliphatic amines (R-NH)₂) 100,000, 20,000-50,000 for secondary aliphatic amine (RR' NH), 200-300 for primary aromatic amine (Ar-NH), 15 for urea (R-NH-CO-NH-R), 0.3 for carbamate (R-NH-CO-O-R), and 0.3 for amide (RCO-NH)₂) Is 0.1. If it is assumed that all OH (hydroxyl) groups are primary hydroxyl groups (this is not the case for lignin), the reactivity of the-OH groups in lignin with the NCO groups in isocyanate will be similar to the reactivity of-OH groups in water with NCO groups in isocyanate at similar concentrations. Due to-OH in lignin, NCO in pMDI and-OH in waterThe molar ratio of functional groups is 1.0-1.5: 2.0: 83.1, so one might expect much more OH groups from water to react with NCO groups in a pMDI than with lignin. Thus, only a very small fraction of pMDI is expected to react with OH groups in lignin to form polyurethane linkages. The most predominant reaction is likely to be the reaction of the OH group in water with the NCO group in pMDI to form unstable intermediate structures, further to form amines and CO₂As follows:

H₂O+R-NCO→[RNHCOOH]→CO₂+RNH₂

the amine will further react with NCO groups to form (RNH)₂And (3) CO. In lignocellulosic material panels with pMDI and lignin, only a small portion of the lignin is likely to react with the pMDI to form cross-linked structures in the panel, resulting in adhesion. It is expected that most of the lignin has a strong physical interaction with the lignocellulosic material, resulting in adhesion of the lignocellulosic material and strengthening of the lignocellulosic material panel.

B) Phenolic resin systems (usually phenolic resins plus wax)

When a phenol-formaldehyde resin is used as a binder in the manufacture of lignocellulosic material panels, the dosage of phenolic resin is less than 5 wt% (based on the dry weight of the lignocellulosic material) and most typically about 3 wt% or less. These panels are typically pressed at about 130 ℃ to 150 ℃ in the case of plywood and about 170 ℃ to 180 ℃ in the case of OSB. Under these conditions, a portion of the lignin is expected to participate in the phenolic resin curing reaction and become part of the cross-linked structure of the phenolic resin in the panel being manufactured. The wax may be partially or fully replaced by lignin. Because lignin establishes physical adhesion with lignocellulosic materials and also participates in curing reactions with phenolic resins, lignocellulosic material panels made with phenolic resins and lignin can perform as well or better than lignocellulosic panels made with phenolic resins and waxes.

C) Urea-formaldehyde systems (usually urea-formaldehyde resins plus wax)

When urea-formaldehyde resins are used in the manufacture of lignocellulosic material panels, the dosage of urea-formaldehyde resin is in the range of 6 wt% to 14 wt% (based on the dry weight of the lignocellulosic material) and typically 8 wt% to 12 wt%. Due to the reaction mechanism in this resin system, lignin may not participate in the urea-formaldehyde curing reaction during panel manufacturing.

There is an increasing demand to reduce formaldehyde emissions from composite wood and/or paper products used in buildings. pMDI and polyurethane adhesives (formaldehyde free) for wood product applications have increased significantly, especially in OSB manufacturing. Isocyanate-containing binders and adhesives account for about 10% of the north american wood adhesive market share by volume.

Polyurethane (PU) is considered one of the most versatile polymeric materials, providing a wide range of products with a variety of applications. PU products can be divided into three categories: flexible foams, rigid foams, and other products including coatings, adhesives and binders, sealants, elastomers, and the like. In recent years, the use of formaldehyde-free adhesives and binders, and in particular isocyanate-based and bio-based adhesives, has increased dramatically in wood and wood product applications.

The addition of bio-based products, especially lignocellulose-based products, to polymer systems is a very common and efficient method to produce materials with higher mechanical properties and more environmentally friendly characteristics. Accordingly, much effort has been devoted to incorporating lignin into several lignin-based polyurethane applications (adhesives, foams and binders) because it has a variety of functional groups and particularly different types of hydroxyl groups in its structure.

Us patent 4,317,752 describes a process for producing polyisocyanate lignin-cellulose plastics. In a first step, wood sawdust is cooked with sodium hydroxide at a temperature between 150 ℃ and 220 ℃ yielding a brown viscous liquid which solidifies upon cooling and is ground to a powder. In a second step, the milled powder is mixed with a polyisocyanate (such as toluene diisocyanate or TDI in a 1: 1 ratio by weight, methylene diphenyl diisocyanate or MDI in a 2: 3 ratio) and stirred at a temperature of 20 ℃ to 70 ℃ for 10 to 60 minutes, thereby producing a polyisocyanate-lignin-cellulose prepolymer. In a third step, a curing agent (such as water, aqueous catalyst (such as tertiary amines), organometallic compounds, etc. and organic additives (such as alcohols, aldehydes, carboxylic acids, carboxylic acid chlorides, esters, ethers, ketones) are added and mixed into the polyisocyanate-lignin-cellulose prepolymer to produce a semi-rigid or rigid cellular product.

Us patent 4,486,557 discusses the development of binder formulations comprising a di-or polyisocyanate (20-95 wt.%), such as MDI, a liquid epoxide (5-80% wt.%), and lignin as a diluent (1.0-60% wt.%). These formulations are suggested for use as adhesives for the manufacture of lignocellulosic boards.

Us patent 5,750,201 discusses the development of a process for bonding lignocellulosic material using a polyisocyanate in combination with a lignin solvent and lignin. The lignin solvent, in particular the cyclic urea, is used in an amount in the range from 0.1 to 6.0 wt% based on the weight of the polyisocyanate. The lignin used is an organosolv lignin and is added in an amount ranging from 1 to 5 wt% based on polyisocyanate.

Patent application CA 2,164,467 and patent application CA 2,164,490 discuss the incorporation of lignin into isocyanates to produce lignin-isocyanate prepolymers for polyurethanes. Several steps are disclosed for preparing lignin-based isocyanate prepolymer mixtures, mainly: 1) adding and stirring lignin powder (kraft lignin or organosolv lignin) into PPG or PEG; 2) removing water from the mixture at 60-150 ℃ under vacuum for several hours; 3) the dewatered lignin suspension was slowly dosed and stirred into the isocyanate, heated at 80 ℃ and held at 80-120 ℃ for 2 hours to complete the reaction. The viscosity of the lignin-containing prepolymer mixture depends to a large extent on the lignin type and also the polyisocyanate structure. After 60 days of storage at 50 ℃, the prepolymer mixture did not convert to a gel, indicating that the prepolymer mixture was very stable. Polyurethane foams are produced by mixing a lignin-based isocyanate prepolymer mixture with a polyol containing blowing agents, catalysts, surfactants, chain extenders, crosslinkers, and other additives such as flame retardants.

Patent application WO 2011/097719 describes a method for preparing binders (lignin-based isocyanate binders and lignin-based phenol-formaldehyde resins). For lignin-based isocyanate binders, powdered lignin is dissolved in a solvent (e.g., acetone), MDI is added, and most of the solvent is removed via vacuum distillation. The lignin may also be mixed directly with MDI. The viscosity of the MDI-lignin mixture depends on the lignin content in the mixture and increases over time.

Patent application WO 97/24362 discloses a process for incorporating lignin into polyols and then reacting with isocyanates to form polyurethane products. The lignin is mixed with the polyether polyol with stirring, then heated to about 90 ℃ and stirred to improve the dissolution/dispersion rate. The resulting lignin-polyol solution can be used to make thermoset urethane parts, rigid foams, or coatings by adding isocyanates, catalysts, and other additives.

Patent application CN 104449501 discloses a wood adhesive formulation comprising 0-90% furfural, 0-70% lignin and 10-100% polyisocyanate, preferably 5-75% furfural, 5-50% lignin and 20-90% polyisocyanate. 2-ply plywood made with 70% -40% furfural/10% -40% lignin/20% pMDI at 150 ℃ for 180 seconds had shear strength comparable to plywood made by using phenol-formaldehyde resin in dry and wet conditions (after 48 hours soak).

Patent application CN 104449528A developed a lignin-containing adhesive comprising 20% to 25% lignin, 50% to 60% toluene diisocyanate, 10% to 12% thickener (such as rosin) and water.

Us patent 3,072,634 describes an isocyanate-lignin product obtained by reacting isocyanates (such as butyl isocyanate, phenyl isocyanate) with lignin (such as Indulin a) at a temperature in the range of from 75 ℃ to 110 ℃ with/without solvent.

Us patent 3,577,358 developed a process for producing lignin-isocyanates for plastics, adhesives, flexible and rigid foams. They used several methods of introducing lignin into isocyanates: 1) dissolving lignin in a solvent (such as 1, 4-dioxane, diethylene glycol monolaurate) and then reacting with a polyisocyanate (such as diphenylmethane-4, 4' -diisocyanate (MDI), 80% 2, 4-toluene diisocyanate/20% 2, 6-Toluene Diisocyanate (TDI) at elevated temperature and with/without a catalyst (such as triethanolamine); 2) dispersing lignin in a polyalkylene glycol (e.g., polyethylene glycol with an average MW of 400), mixed polypropylene-ethylene glycol) and then reacting with a polyisocyanate (such as diphenylmethane-4, 4' -diisocyanate, 80% 2, 4-toluene diisocyanate/20% 2, 6-toluene diisocyanate); and 3) dispersing the lignin directly in a polyisocyanate (such as 80% 2, 4-toluene diisocyanate and 20% 2, 6-toluene diisocyanate) and then reacting at elevated temperature (e.g., 10 minutes at 70 ℃ or 7 minutes at 120 ℃).

Glaser et al (1982) "Hydroxy propyl L ignin-Isocyanate combining adhesives for Wood and cellulose Fibers", The Journal of adhesives, 14: 3, 233-.

More recently, U.S. patent 9,598,529 discloses the production of lignin-based polyurethane products. In a first step, the lignin is mixed with an isocyanate. Depending on the final product, other additives such as flame retardants, blowing agents, polyols, surfactants, catalysts and blowing agents may be added. To manufacture a wood composite material, several steps are taken: 1) mixing the dried lignin and isocyanate in a ratio of 1: 2 by weight; 2) adding the mixture to wood particles in a weight ratio of 1: 2; 3) the resulting mixture of wood particles and isocyanate-lignin was molded in a press and kept in an oven at 70 ℃ overnight; 4) after cooling to room temperature, the wood composite material is released from the press.

Thus, several attempts have been made in the past to incorporate lignin into polyisocyanates to make polyurethane products. However, most of the methods described above have one or more disadvantages that make them unavailable for commercial use. Such disadvantages include, but are not limited to: 1) in the case of organic solvents used for the mixing/dispersion of lignin and isocyanate, provisions must be made to remove and recover the solvent-which makes such processes very expensive, wherein, in addition, the resulting mixture may still require further mixing; 2) in the case where the lignin is dissolved/dispersed in the polyester polyol or polyether polyol before mixing with the polyisocyanate, the stability of the resulting mixture seems to be limited; and 3) in case of dissolving/dispersing lignin directly into the polyisocyanate, the applicability of this method seems to be limited to polyurethane foams only. In addition, in such cases, the lignin-isocyanate mixture is not very stable and the viscosity reaches very high levels, especially at high lignin contents (20-30% by weight) in the mixture. As a result, once added to the fiber or wood furnish, it can prematurely and non-uniformly polymerize, leading to plugging and other problems, especially at elevated temperatures.

Isocyanates (including pMDI) are a class of chemicals that have some of the most numerous industrial applications. When allowed to react with the polyol, polyurethane products are formed, such as polyurethane adhesives, polyurethane foams, and the like. The polyol can be any chemical containing hydroxyl groups in the molecular structure such as ethylene glycol, sugars, lignin, cellulose, and the like. Even water can be considered a polyol.

Isocyanates can also react with themselves via dimerization to form uretidiodione (dimer), with themselves via trimerization to form isocyanurates (trimer), with carbodiimide formation, and the like. Diisocyanate (such as MDI) reactions are generally much more complex than monoisocyanate reactions.

Accordingly, there remains a need to provide a method of incorporating lignin into lignocellulosic materials that enables the manufacture of lignin-based lignocellulosic material panels (such as wood composite panels and other products) with wood adhesives containing isocyanates without the problems encountered in the prior art.

Disclosure of Invention

There is provided a method of producing a wood product comprising: blending wood material with lignin, isocyanate or other adhesive and a portion of wax or no wax to produce a resinated material; forming a pad from the resinated material; and compressing or molding the mat at an elevated temperature to produce a wood product.

In embodiments, the wood material and lignin are first blended in a blender to produce a wood material-lignin mixture; flowing the wood material-lignin mixture into a digester, compressing the wood material-lignin mixture; steaming the compressed wood material-lignin mixture by injecting pressure steam; refining the compressed wood material-lignin mixture to produce refined fibers; and blending the refined fibers with an isocyanate and a portion of the wax or no wax to produce the resinated material.

In another embodiment, the methods described herein comprise: incorporating the lignin into the wood material by a plug screw, producing a wood material-lignin mixture; flowing the wood material-lignin mixture into a digester, compressing the wood material-lignin mixture; steaming the compressed wood material-lignin mixture by injecting pressure steam; refining the compressed wood material-lignin mixture to produce refined fibers; and blending the refined fibers with an isocyanate and a portion of the wax or no wax to produce the resinated material.

In embodiments, flowing the wood material through a plug screw compresses the wood material; flowing the compressed wood material into a digester, wherein the lignin is incorporated, producing a compressed wood material-lignin mixture; steaming the compressed wood material-lignin mixture by injecting pressure steam; refining the compressed wood material-lignin mixture to produce refined fibers; and blending the refined fibers with an isocyanate and a portion of the wax or no wax to produce the resinated material.

In further embodiments, flowing the wood material through a plug screw compresses the wood material; flowing the compressed wood material into a digester; steaming the compressed wood material by injecting pressure steam; incorporating the lignin into the compressed wood material, producing a compressed wood material-lignin mixture; refining the compressed wood material-lignin mixture to produce refined fibers; and blending the refined fibers with an isocyanate and a portion of the wax or no wax to produce the resinated material.

In embodiments, flowing the wood material through a plug screw compresses the wood material; flowing the compressed wood material into a digester; steaming the compressed wood material by injecting pressure steam; refining the compressed wood material to produce refined fibers; incorporating the lignin into the refined fibres via a blow-line (blow-line) to produce a refined fibre-lignin mixture; blending the refined fiber-lignin mixture with an isocyanate and a portion of the wax or no wax to produce the resinated material.

In another embodiment, flowing the wood material through a plug screw compresses the wood material; flowing the compressed wood material into a digester; steaming the compressed wood material by injecting pressure steam; refining the compressed wood material to produce refined fibers; blending the refined fiber into the isocyanate and a portion of the wax or no wax, resulting in a refined fiber-isocyanate mixture; drying the refined fiber-isocyanate mixture; and blending lignin into the refined fiber-isocyanate mixture to produce the resinated material.

In embodiments, the pressure steam has a temperature between 130 ℃ and 190 ℃.

In another embodiment, the wood material is wood chips or wood sawdust.

In further embodiments, the wood product is an insulation board and/or a molded product.

In another embodiment, the wood product is a low density insulation board, a Medium Density Fiberboard (MDF), a High Density Fiberboard (HDF), a fiber-based insulation board, a paper product, or a non-wood lignocellulosic board.

In another embodiment, the wood product is Particle Board (PB), Oriented Strand Board (OSB), bark board, or non-wood lignocellulosic board.

In embodiments, the lignin is in the form of a powder or in suspension.

In further embodiments, the lignin is kraft lignin, soda lignin, hydrolyzed lignin, lignosulfonate, organosolv lignin, dioxane acid hydrolyzed lignin, milled wood lignin, or karaoke lignin.

In another embodiment, wherein the wood material is in the form of wood particles and the wood adhesive is a urea-formaldehyde resin or a phenol-formaldehyde resin or an isocyanate resin to produce particle board.

In embodiments, the wood material is in the form of a wood strand, wherein the individual strands are about 2.0-2.5cmx 10-15cm, and the wood adhesive is a phenol-formaldehyde resin or an isocyanate resin to produce an OSB panel.

Also provided is a method of producing a wood product, comprising: blending wood chips with lignin in a blender to produce a wood chip-lignin mixture; flowing the wood chip-lignin mixture through a plug screw, compressing the wood chip-lignin mixture; flowing the compressed wood chip-lignin mixture into a digester; steaming the compressed wood chip-lignin mixture by injecting pressure steam; refining the compressed wood chips-lignin mixture to produce refined fibers; adding isocyanate and a portion of wax or no wax to the refined fiber to produce an isocyanate-refined fiber mixture; drying the isocyanate-refined fiber mixture to produce a dry resinated fiber; forming a mat from the dry resinated fibers; and compressing or molding the mat to produce the wood product.

In another embodiment, a method of producing a wood product, comprising: blending wood chips with lignin; flowing the wood chip and lignin mixture through a plug screw and compressing the wood chip and lignin, producing a compressed wood chip-lignin mixture, flowing the compressed wood chip-lignin mixture into a digester; refining the compressed wood chip-lignin mixture by injecting pressure steam to cook the compressed wood chip-lignin mixture to produce refined fibers; adding isocyanate and a portion of wax or no wax to the refined fiber to produce an isocyanate-refined fiber mixture; drying the isocyanate-refined fiber mixture to produce a dry resinated fiber; forming a mat from the dry resinated fibers; and compressing or molding the mat to produce the wood product.

In another embodiment, a method of producing a wood product, comprising: blending wood chips; flowing the wood chips through a plug screw and compressing the wood chips; flowing the compressed wood chips into a digester, wherein the lignin is incorporated, producing a compressed wood chip-lignin mixture; steaming the compressed wood chip-lignin mixture by injecting pressure steam; refining the compressed wood chips-lignin mixture to produce refined fibers; adding isocyanate and a portion of wax or no wax to the refined fiber to produce an isocyanate-refined fiber mixture; drying the isocyanate-refined fiber mixture to produce a dry resinated fiber; forming a mat from the dry resinated fibers; and compressing or molding the mat to produce the wood product.

Also provided is a method of producing a wood product, comprising: blending wood chips; flowing the wood chips through a plug screw and compressing the wood chips; flowing the compressed wood chips into a digester; (ii) steaming the compressed wood chips by injection of pressure steam and subsequently incorporating the lignin into the compressed wood chips, producing a wood chips-lignin mixture; refining the compressed wood chips-lignin mixture to produce refined fibers; adding isocyanate and a portion of wax or no wax to the refined fiber to produce an isocyanate-refined fiber mixture; drying the isocyanate-refined fiber mixture to produce a dry resinated fiber; forming a mat from the dry resinated fibers; and compressing or molding the mat to produce the wood product.

Also provided is a method of producing a wood product, comprising: blending wood chips; flowing the wood chips through a plug screw and compressing the wood chips; flowing the compressed wood chips into a digester; steaming the compressed wood chips by injecting pressure steam; refining the compressed wood chips to produce refined fibers; incorporating the lignin into the refined fiber through a blowing line to produce a refined fiber-lignin mixture; adding isocyanate and a portion of wax or no wax to the refined fiber-lignin mixture to produce an isocyanate-refined fiber mixture; drying the isocyanate-refined fiber mixture to produce a dry resinated fiber; forming a mat from the dry resinated fibers; and compressing or molding the mat to produce the wood product.

In a further embodiment, there is provided a method of producing a wood product comprising: blending wood chips; flowing the wood chips through a plug screw and compressing the wood chips; flowing the compressed wood chips into a digester; steaming the compressed wood chips by injecting pressure steam; refining the compressed wood chips to produce refined fibers; adding isocyanate and a portion of wax or no wax to the refined fiber to produce an isocyanate-refined fiber mixture; drying the isocyanate-refined fiber mixture to produce a dry resinated fiber; blending lignin into the dry resinated fibers, producing a resinated material; forming a mat from the dry resinated material; and compressing or molding the mat to produce the wood product.

In embodiments, there is also provided a lignocellulosic material produced by the methods described herein.

Drawings

Reference will now be made to the drawings.

Figure 1 presents in (a) a known method for producing fibreboards using pMDI; a method for producing a fiberboard according to an embodiment of the present disclosure is presented in (B); in (C) a known process for producing particle board or OSB is presented; and in (D) a process for producing a particle board or OSB according to another embodiment of the present disclosure is presented.

Figure 2 shows a press cycle diagram.

Detailed Description

In accordance with the present disclosure, lignin-isocyanate wood products, compositions, preparations, and combinations thereof are provided.

Disclosed herein are wood compositions and methods for making wood compositions, as well as wood products.

The wood compositions described herein comprise lignin derived from a variety of natural sources, an isocyanate compound containing two or more isocyanate functional groups, and a suitable dispersant. Other materials may be added as catalysts to promote the reaction of the isocyanate and polyurethane in the described compositions. "lignin" generally refers to a group of phenolic polymers that impart strength and rigidity (rigidness) to plant materials. Lignin is a complex polymer and tends to be referred to in the above sense. The lignin may comprise any one or more of the following: several possible industrial lignin preparations such as kraft lignin, by-products of the kraft pulping process, soda lignin, by-products of the soda pulping process, lignosulfonates, by-products of the sulfite pulping process, and by-products of organosolv lignin, bioethanol and/or other solvent processes, as well as other lignin preparations such as dioxane acid hydrolyzed lignin, milled wood lignin, krasone lignin (klasonlignin), and the like. Lignin also as used herein also encompasses other phenolic polymers produced by chemical, thermochemical or enzymatic treatment of lignocellulosic material (e.g., wood) to produce sugar-based chemicals and lignin. One such example is hydrolyzed lignin produced by the method described in U.S. patent application 2011/0143411, which involves alkaline treatment of wood, disc refining, and enzymatic treatment of the resulting biomass to break down the carbohydrate fraction of the wood furnish. The residual biomass of this process is largely composed of lignin and carbohydrates chemically and/or physically attached to the lignin.

By "lignin component" is meant any lignin-containing material. The lignin component may be derived from industrial lignin preparations or other lignin preparations derived from renewable resources, in particular from lignocellulosic materials. The lignin component can be a material or composition into which a modified, treated, or purified portion of lignin, such as propoxylated lignin, is incorporated.

As described herein, lignin is used to prepare fiber products (e.g., Medium Density Fiberboard (MDF), High Density Fiberboard (HDF), fiber-based insulation board, and potentially paper products) as well as wood products such as Particle Board (PB) and Oriented Strand Board (OSB), etc. (bark boards, non-wood lignocellulosic boards) by using novel methods according to embodiments described herein depending on the end product. Thus, the methods described herein are not based on mixing lignin with solvents and/or isocyanates, which requires pumps, tanks and mixers to prepare the solution/mixture and may lead to several problems, such as: high viscosity in case lignin is dissolved in polyols; in the case of the preparation of lignin-isocyanate mixtures, pumping and plugging problems due to the high viscosity of the mixture and its potential prepolymerization (more particularly during the addition of the mixture to the blowing line for the manufacture of MDF); and short shelf life of the mixture due to moisture in the lignin and the reaction of the lignin itself with the isocyanate over time.

Accordingly, a method is provided for improving the properties (such as water resistance and dimensional stability) of Medium Density Fiberboard (MDF), particleboard, OSB board and/or other wood products by incorporating lignin at various stages of production of such panels or wood products, rather than as an integrated formulation of wood adhesives (such as lignin-pMDI complexes). Direct reaction or polymerization between lignin and wood adhesives (such as pMDI) is avoided before applying the lignin and wood adhesives and mixing them with the lignocellulosic material to form a homogeneous resinated lignocellulosic material. Such reactions should occur after formation of the mat of resinated lignocellulosic material and during mat pressing in a press at elevated temperatures. Wood products contemplated herein do not require any other adhesives (e.g., epoxies) found in the prior art;

for the dry process of fiberboard manufacture, lignin can be incorporated at different locations of the process: 1) at the start of the process, the fibre is modified by lignin by blending with a feedstock such as wood chips or sawdust before the refiner, resulting in reduced requirements for pMDI resin and/or wax. Modifying wood fibers with lignin using the methods described herein helps create several new opportunities for saving chemicals (e.g., pMDI and waxes) in the manufacture of fiberboard (e.g., MDF) and/or low density insulation boards. The methods described herein are also applicable to other resin systems (other than pMDI), such as, for example, phenol-formaldehyde and/or urea-formaldehyde resin systems to reduce wax consumption. 2) The lignin may also be incorporated between the raw material bin feeder and the plug screw. 3) The lignin may also be incorporated directly into the digester. 4) The lignin may also be incorporated between the digester and the refiner. 5) The lignin may also be incorporated at the blowing line after the refiner. Finally 6) it is also possible to incorporate lignin into the dried fibre at the end of the drying process. pMDI resin was applied to the blow line with the wet fibers and the resinated fibers were dried at a flash tube dryer. The dried resinated fibers are then collected and then formed into a resinated fiber mat and then pressed into a board with a press at elevated temperature. It is also contemplated to apply the pMDI resin to the dried fibers. A resinated fibrous mat is then formed and then pressed with a press at elevated temperature into a fibrous board to achieve the target density. For OSB manufacture, strips or flakes of about 1.5-2.5cm by 10-15cm are prepared from debarked wood logs and dried to the desired moisture content. Lignin (in the form of a suspension or powder) is incorporated into a rotary blender at room temperature along with wood strands or flakes, and then other additives and pMDI are introduced into the blender via a rotating disk in the desired amounts. A mat of resinated tapes is then formed and pressed into OSB boards at elevated temperatures to achieve the target density.

The particle board process is similar to the OSB process. The feedstock is wood particles rather than strips. Fine particles are typically used in the skin layers and coarse particles are used in the core layer. As similarly in the OSB process, lignin will be incorporated into the wood particles in the blender. pMDI was blended into wood particles in a blender via an air pressurized nozzle. The mat of resinated wood particles is then formed into a three-layer sandwich structure at a weight ratio of skin layer to core layer to skin layer, and the mat is then pressed into a board at elevated temperature to achieve the target density. Wood particles can be used to make uniform particle board.

In these cases, when lignin and pMDI are introduced separately into the manufacturing process, oligomers or prepolymers of lignin and pMDI are not formed. Wood can be in different forms (such as wood fibers, wood particles, wood flakes, etc.) depending on the manufacturing process and product of the resinated fibers or flakes or particles (e.g., fiberboard, particle board, OSB, etc.). There may be a small portion of lignin and pMDI in direct contact, and they may or may not have a reaction between lignin and pMDI, as lignin needs to compete with water to react with pMDI. In the case of a weight ratio of lignin, pMDI and moisture of 3% wt: 8% wt, the ratio of-OH groups in lignin to NCO groups in pMDI to OH groups in moisture will be 1.0-1.5: 2.0: 83. If only a small portion of the lignin is contacted with the pMDI, the chance of a reaction between the lignin and the pMDI will be even lower. Without a catalyst, the reaction of NCO groups in pMDI with OH groups in lignin and moisture would be low at room temperature. This indicates that the chance of formation of oligomers or prepolymers of lignin and pMDI in the resinated material prior to pressing will be quite low. At elevated temperatures, all reactions are accelerated.

More particularly, as depicted in fig. 1A, for the production of, for example, fiberboard, wood chips 10 are deposited in a bin 12, wherein twin screws 14 and/or plug screws 16 that compress the wood chips are used to control the flow rate of the wood chips from the bin 12 to a digester 18. The addition of steam in digester 18 allows for stable conditioning of the wood chips to be processed. The processed wood chips are then discharged to a refiner 20 for refining, thereby producing refined fibers. The refined fibers are then introduced through a blow line 22 and dried in a flash tube dryer 24 and a dryer 26 to produce dry resinated fibers. As is known in the art, pMDI and wax are typically added directly into the blow line 22, and then a mat 28 is formed from dry resinated fibers and compressed 30 to produce a panel 32, such as an MDF panel.

According to one embodiment, to avoid pre-mixing and pre-polymerization/reaction of lignin with isocyanate, lignin is added directly to the wood chips 10 (for MDF), wood strands (for OSB), wood particles (for particleboard), or wood fibers (for wood fiber based insulation board) in blender 11 as shown in fig. 1B. Both wet and dry lignin can be used, as the lignin is added in the form of a pulp to wood chips, wood strands, wood particles or wood fibers (the latter case for insulation boards). Alternatively, the lignin may also be fed at a location between the bin 12 and the plug screw 16 or twin screws such that it is fed into the digester 18 with the wood chips or before the refiner 20. According to another embodiment, mostly applied to MDF, lignin is added after the refining and drying process and more specifically in the cyclone 26. This approach avoids the plugging problems caused by the high viscosity of the lignin-isocyanate mixture and the pre-reaction of the two when adding pMDI in parallel with lignin to the blowing line.

Thus, in the case of MDF, lignin can be added, for example, to the wood chips 10, while isocyanate (pMDI) is added as usual-in the blowing line 22 (after refining) -to the wood fibers containing lignin. This approach not only allows for the replacement of a significant portion of the isocyanate, but it also allows for the replacement of significant amounts of paraffin wax, which is typically added to wood fibers to increase their hydrophobicity and ultimately improve the reactivity of pMDI and/or other adhesive formulations, due to the hydrophobic nature of lignin.

According to another embodiment, mostly applied to MDF, lignin is added after the refining and drying process and more specifically in the cyclone 26. This approach avoids the plugging problems due to the high viscosity of the lignin-isocyanate mixture and the pre-reaction of pMDI with lignin in the blowing line.

As seen in fig. 1C, known methods for producing particle board and OSB generally begin by drying wood chips or particles 40 to a target moisture 42. The dried wood chips or particles are then blended 44 with wax, pMDI and water in such a way as to produce a resinated material 46. As described above for the fiberboard process, mat 48 is formed from resinated material 46 and compressed 52 to produce a panel 52, such as an OSB or particle board panel. As contemplated herein, the lignin suspension or powder may also be incorporated into the blender 44 separately rather than as a premixed pMDI-lignin mixture (see fig. 1D). Using this approach, a reduced amount of wax and pMDI can be achieved without negatively affecting the properties of the final plate/panel 52.

Thus, disclosed herein is a novel method of blending lignin with wood and/or other lignocellulosic materials by mechanical refining at elevated temperature and steam pressure that can effectively soften the lignin (by reaching or exceeding its glass transition temperature), allowing the lignin to successfully and uniformly adhere to wood fibers and/or wood particles as a result of this method, it has been demonstrated that washed kraft lignin (otherwise known as low residual content (L RC lignin)) can be used in MDF production to replace wax, either in whole or in part, and has the potential to partially replace pMDI adhesive resins.

Thus, a method of producing a fibre product or wood product is described which results in a reduction in the amount of wax and/or isocyanate required.

The present invention thus provides a novel process for modifying lignocellulosic material suitable for the manufacture of new or improved fibrous products such as medium density fiberboard, insulation board, molded fiber products, new grades of paper and packaging products, and the like, by lignin through mechanical refining at elevated temperature and pressure, thereby imparting improved properties to the lignocellulosic material, in particular, a novel process for incorporating washed kraft lignin (L RC lignin) in place of wax for dimensional stability of panel products and/or partially in place of adhesive resins to save costs in the production of MDF is provided.

The disclosure will be more readily understood by reference to the following examples.