Preparation method of lignin-based biomass formaldehyde-free adhesive for shaving board

Abstract

The invention discloses a preparation method of a shaving board lignin-based biomass formaldehyde-free adhesive, and relates to the technical field of environment-friendly adhesives, the preparation method comprises the following steps: step 1, mixing animal collagen and inorganic base, and carrying out ultrasonic treatment to obtain activated protein; step 2, mixing and stirring the modified activated lignin, activated protein and an amino resin cross-linking agent in a mass ratio of (42-50): (17-23): (5-20) for 10-30 minutes, and controlling the stirring temperature to be 30-45 DEG C to obtain an initial material of the formaldehyde-free adhesive; and step 3, adding the functional additive into the formaldehyde-free adhesive initial material, and carrying out heat treatment and stirring to obtain the functional formaldehyde-free adhesive. The formaldehyde-free environment-friendly adhesive has the effect of remarkably improving the bonding strength while being formaldehyde-free and environment-friendly.

Description

Technical Field

[0001] The present application relates to the technical field of environmentally friendly adhesives, and in particular to a method for preparing a lignin-based biomass formaldehyde-free adhesive for particleboard. Background Art

[0002] Artificial boards are made of wood or other non-wood plants as raw materials, which are separated into various unit materials through certain mechanical processing, and then reassembled and hot-pressed to form boards or molded products after applying adhesives.

[0003] At present, the most widely used industrial adhesives for artificial boards are "trialdehyde glues" represented by urea-formaldehyde resin adhesives, phenolic resin adhesives, and melamine adhesives, which have the advantages of high bonding strength, low price, simple manufacturing process, and ease of use. However, these three types of adhesives all use formaldehyde as a synthetic raw material, which will release harmful substances such as formaldehyde during production and use, and the release of formaldehyde is a long-term slow-release process that endangers human health. With the increasing awareness of environmental protection, increasingly stringent national standards, and intensified market competition, many companies are actively demanding product differentiation in order to improve their market competitiveness. Formaldehyde-free adhesives have become a real need for artificial board companies.

[0004] A Chinese patent application document with publication number CN115806802A discloses a method for preparing a lignin formaldehyde-free adhesive for particleboard. The method for preparing the lignin formaldehyde-free adhesive for particleboard comprises homogenizing lignin, an acid catalyst, and a curing agent at room temperature to obtain the lignin formaldehyde-free adhesive; the lignin is alkali lignin or lignin sulfonate; the acid catalyst is selected from sulfuric acid and phosphoric acid; and the curing agent is selected from polyols and polyamines.

[0005] However, although this preparation method treats lignin through an acid catalyst and a curing agent, it is still difficult to effectively improve the activity of lignin. Therefore, it is difficult to ensure the bonding strength when using the particleboard lignin-based biomass formaldehyde-free adhesive obtained by this preparation method, which needs to be improved. Summary of the invention

[0006] In view of this, the purpose of this application is to provide a method for preparing a particleboard lignin-based biomass formaldehyde-free adhesive, so as to achieve the purpose of significantly improving the bonding strength while being formaldehyde-free and environmentally friendly. The specific scheme is as follows:

[0007] A method for preparing a particleboard lignin-based biomass formaldehyde-free adhesive comprises the following steps:

[0008] Step 1, mixing animal collagen with inorganic alkali and subjecting them to ultrasonic treatment to obtain activated protein;

[0009] Step 2, mixing the modified activated lignin with the activated protein and the amino resin cross-linking agent in a mass ratio of 42-50:17-23:5-20 for 10-30 minutes, controlling the stirring temperature to 30-45° C., to obtain a formaldehyde-free adhesive raw material;

[0010] Step 3: adding the functional additives into the initial material of the formaldehyde-free adhesive, heat-treating and stirring to obtain the functional formaldehyde-free adhesive.

[0011] Preferably, the modified activated lignin is obtained by dissolving lignin in an ethanol solution, mixing it with an activator and subjecting it to ultrasonic treatment, and the mass ratio of the lignin to the activator is controlled to be 10-30:15-190, and the temperature is 15-45°C.

[0012] Preferably, the activator is obtained by mixing sulfuric acid or phosphoric acid with 3,3′-thiobis-1-propylene, and the pH of the activator is ≥3.0.

[0013] Preferably, after the modified activated lignin is mixed with the activator and ultrasonically treated, an alkali solution is used to adjust the pH to 7.0-8.5.

[0014] Preferably, the lignin is alkali lignin or lignin sulfonate.

[0015] Preferably: the functional additives include at least one of a water retaining agent, a thickening agent and an antibacterial agent; the water retaining agent is at least one of ammonium polyacrylate, sodium alginate, hydroxypropyl methylcellulose and gelatin; the thickening agent is at least one of an aqueous thickening resin, cellulose nanocrystals, and copolymer ammonium salts; the antibacterial agent is at least one of an inorganic antibacterial agent, an imidazole antibacterial agent, a quaternary ammonium salt antibacterial agent, and a phenolic antibacterial agent.

[0016] Preferably, the mass ratio of the functional additive to the formaldehyde-free adhesive is 0-3:97-100.

[0017] Preferably, the heat treatment is carried out by microwave heat treatment, and the heat treatment temperature is controlled to be 40-50° C., low-speed stirring is continued for 0.2-0.8 h, and the low-speed stirring speed is 60-180 r / min.

[0018] Preferably: the amino resin crosslinking agent is Wherein, Y1 and Y3 are each independently a C1-C3 alkyl or silane group whose hydrogen group is replaced by at least one halogen, carboxyl, hydroxyl, amino, aldehyde, thiol, cyano, sulfonic acid, epoxy, acid anhydride, acyl chloride, acrylamide, or isocyanate group; Y2 is a C1-C6 alkyl group; and Y4 is a methane or ethyl group.

[0019] Preferably, the amino resin cross-linking agent is n-butyl etherified melamine resin, partially methyl etherified melamine resin or high imino resin.

[0020] It can be seen from the above scheme that the present application provides a method for preparing a particleboard lignin-based biomass formaldehyde-free adhesive, and the method for preparing a particleboard lignin-based biomass formaldehyde-free adhesive has the following beneficial effects:

[0021] 1. The animal collagen is activated by inorganic alkali to activate the amino, hydroxyl and side chain groups in the protein, and then the activated protein and the modified activated lignin are cross-linked with an amino resin cross-linking agent to form a stable cross-linked grid structure, thereby significantly improving the bonding strength of the particleboard lignin-based biomass formaldehyde-free adhesive obtained by the preparation method;

[0022] 2. By adding functional additives, the obtained functional formaldehyde-free adhesive has corresponding anti-curing, high viscosity and / or antibacterial effects, so as to significantly improve the usability and use effect of the functional formaldehyde-free adhesive;

[0023] 3. The lignin is activated by an activator to obtain the corresponding modified activated lignin, so that the modified activated lignin is green and environmentally friendly, thereby avoiding the release of formaldehyde. At the same time, the surface active groups in the modified activated lignin and the activated protein form a stable cross-linked grid structure under the action of the amino resin cross-linker, thereby significantly improving the bonding strength of the particleboard lignin-based biomass formaldehyde-free adhesive obtained by the preparation method, and extending the glue application open time during use, avoiding the problem of high difficulty in use due to high annual temperature and short open time, thereby significantly improving practicality;

[0024] 4. The amino resin cross-linking agent can effectively improve the effect of cross-linking, curing and activating protein and modifying and activating lignin, thereby achieving the purpose of significantly improving the bonding strength while being formaldehyde-free and environmentally friendly. DETAILED DESCRIPTION

[0025] The following will be clearly and completely described in conjunction with the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0026] The following is a detailed description of the preparation method of the particleboard lignin-based biomass formaldehyde-free adhesive of the present application.

[0027] The inorganic alkali used may be any existing material such as sodium hydroxide, potassium hydroxide, calcium hydroxide, etc., and sodium hydroxide is used in this embodiment, which will not be described in detail here.

[0028] A method for preparing a particleboard lignin-based biomass formaldehyde-free adhesive comprises the following steps:

[0029] Step 1, mixing animal collagen with inorganic alkali and subjecting them to ultrasonic treatment to obtain activated protein;

[0030] Step 2, mixing the modified activated lignin with the activated protein and the amino resin cross-linking agent in a mass ratio of 42-50:17-23:5-20 for 10-30 minutes, controlling the stirring temperature to 30-45° C., to obtain a formaldehyde-free adhesive raw material;

[0031] Step 3, adding functional additives to the formaldehyde-free adhesive raw material, controlling the mass ratio of the functional additives to the formaldehyde-free adhesive raw material to be 0-3:97-100, microwave heat treatment and stirring to obtain a functional formaldehyde-free adhesive, and controlling the heat treatment temperature to be 40-50°C, continuing low-speed stirring for 0.2-0.8h, and the low-speed stirring speed is 60-180r / min.

[0032] Among them, the modified activated lignin is obtained by dissolving alkali lignin or lignin sulfonate in an ethanol solution, and then mixing with an activator and ultrasonic treatment, and the mass ratio of alkali lignin or lignin sulfonate to the activator is controlled to be 10-30:15-190, and the temperature is 15-45°C. The activator is obtained by mixing sulfuric acid or phosphoric acid with 3,3′-thiobis-1-propylene, and the pH of the activator is ≥3.0. It should be noted that after the modified activated lignin is mixed with the activator and ultrasonic treatment, an alkali solution is also used to adjust the pH to 7.0-8.5 for standby use, which is suitable for mixing and cross-linking the modified activated lignin with a pH of 7.0-8.5 with the activated protein, and the alkali solution uses a sodium hydroxide solution.

[0033] At the same time, the energy additive includes at least one of a water retaining agent, a thickening agent and an antibacterial agent. Among them, the water retaining agent is at least one of ammonium polyacrylate, sodium alginate, hydroxypropyl methylcellulose and gelatin. The thickening agent is at least one of an aqueous thickening resin, cellulose nanocrystals, and copolymer ammonium salts. The antibacterial agent is at least one of an inorganic antibacterial agent, an imidazole antibacterial agent, a quaternary ammonium salt antibacterial agent, and a phenolic antibacterial agent.

[0034] The amino resin crosslinking agent is n-butyl etherified melamine resin, partially methyl etherified melamine resin or high imino resin. When the amino resin crosslinking agent is When Y1 and Y3 are each independently a C1-C3 alkyl or silane group whose hydrogen group is substituted by at least one halogen, carboxyl, hydroxyl, amino, aldehyde, mercapto, cyano, sulfonic acid, epoxy, anhydride, acyl chloride, acrylamide or isocyanate group; Y2 is a C1-C6 alkyl group; and Y4 is a methane or ethyl group.

[0035] Embodiment 1

[0036] A method for preparing a particleboard lignin-based biomass formaldehyde-free adhesive comprises the following steps:

[0037] Step 1, mixing animal collagen with inorganic alkali and subjecting them to ultrasonic treatment to obtain activated protein;

[0038] Step 2, the modified activated lignin, activated protein and amino resin cross-linking agent are mixed and stirred at a mass ratio of 42:17:5 for 10 minutes, and the stirring temperature is controlled at 30° C. to obtain a formaldehyde-free adhesive raw material;

[0039] Step 3: Add the functional additive to the initial formaldehyde-free adhesive, control the mass ratio of the functional additive to the initial formaldehyde-free adhesive to be 0, perform microwave heat treatment and stirring to obtain the functional formaldehyde-free adhesive, control the heat treatment temperature to 40°C, continue low-speed stirring for 0.2h, and the low-speed stirring speed is 60r / min.

[0040] Among them, the modified activated lignin is obtained by dissolving alkali lignin in an ethanol solution, and then mixing it with an activator and ultrasonically treating it. The mass ratio of alkali lignin to the activator is controlled to be 2:3, and the temperature is 15°C. The activator is obtained by mixing phosphoric acid with 3,3′-thiobis-1-propylene, and the pH of the activator is 3.0. It should be noted that after the modified activated lignin is mixed with the activator and ultrasonically treated, an alkali solution is also used to adjust the pH to 7.0 for standby use, which is suitable for mixing and cross-linking the modified activated lignin with a pH of 7.0 with the activated protein, and the alkali solution uses a sodium hydroxide solution.

[0041] At the same time, the energy additives include a water retaining agent and a thickening agent, wherein the water retaining agent is ammonium polyacrylate and the thickening agent is a water-based thickening resin.

[0042] Amino resin crosslinker is Among them, Y1 is an ethyl group in which a hydrogen group is replaced by a cyano group, Y3 is a methane group in which a hydrogen group is replaced by an acyl chloride group, Y2 is an ethyl group, and Y4 is a methane group.

[0043] Embodiment 2

[0044] A method for preparing a particleboard lignin-based biomass formaldehyde-free adhesive comprises the following steps:

[0045] Step 1, mixing animal collagen with inorganic alkali and subjecting them to ultrasonic treatment to obtain activated protein;

[0046] Step 2, the modified activated lignin, activated protein and amino resin cross-linking agent are mixed and stirred at a mass ratio of 46:20:11 for 18 minutes, and the stirring temperature is controlled at 36° C. to obtain a formaldehyde-free adhesive raw material;

[0047] Step 3: Add functional additives to the initial material of formaldehyde-free adhesive, control the mass ratio of functional additives to formaldehyde-free adhesive to be 1:99, perform microwave heat treatment and stirring to obtain functional formaldehyde-free adhesive, control the heat treatment temperature to 45°C, continue low-speed stirring for 0.5h, and the low-speed stirring speed is 120r / min.

[0048] Among them, the modified activated lignin is obtained by dissolving lignin sulfonate in an ethanol solution, and then mixing with an activator and ultrasonic treatment, and the mass ratio of lignin sulfonate to activator is controlled to be 2:11, and the temperature is 30°C. The activator is obtained by mixing sulfuric acid with 3,3′-thiobis-1-propylene, and the pH of the activator is 4.0. It should be noted that after the modified activated lignin is mixed with the activator and ultrasonic treatment, an alkali solution is also used to adjust the pH to 8.0 for standby use, which is suitable for mixing and cross-linking the modified activated lignin with a pH of 8.0 with the activated protein, and the alkali solution is a sodium hydroxide solution.

[0049] At the same time, the energy additives include a water retaining agent, a thickening agent and an antibacterial agent. Among them, the water retaining agent is sodium alginate. The thickening agent is a copolymer ammonium salt. The antibacterial agent is a quaternary ammonium salt antibacterial agent.

[0050] Amino resin crosslinker is Among them, Y1 is a propane group in which a hydrogen group is replaced by a hydroxyl group, Y3 is an ethyl group in which a hydrogen group is replaced by a sulfonic acid group, Y2 is a butane group, and Y4 is an ethyl group.

[0051] Embodiment 3

[0052] A method for preparing a particleboard lignin-based biomass formaldehyde-free adhesive comprises the following steps:

[0053] Step 1, mixing animal collagen with inorganic alkali and subjecting them to ultrasonic treatment to obtain activated protein;

[0054] Step 2, the modified activated lignin, activated protein and amino resin cross-linking agent are mixed and stirred at a mass ratio of 50:23:20 for 30 minutes, and the stirring temperature is controlled at 45° C. to obtain a formaldehyde-free adhesive raw material;

[0055] Step 3: Add functional additives to the initial material of formaldehyde-free adhesive, control the mass ratio of functional additives to formaldehyde-free adhesive to be 3:97, microwave heat treatment and stirring to obtain functional formaldehyde-free adhesive, and control the heat treatment temperature to 50°C, continue low-speed stirring for 0.8h, and the low-speed stirring speed is 180r / min.

[0056] Among them, the modified activated lignin is obtained by dissolving alkali lignin or lignin sulfonate in an ethanol solution, and then mixing with an activator and ultrasonic treatment, and the mass ratio of alkali lignin or lignin sulfonate to the activator is controlled to be 3:19, and the temperature is 45°C. The activator is obtained by mixing phosphoric acid with 3,3′-thiobis-1-propylene, and the pH of the activator is 3.5. It should be noted that after the modified activated lignin is mixed with the activator and ultrasonic treatment, an alkali solution is also used to adjust the pH to 8.5 for standby use, which is suitable for mixing and cross-linking the modified activated lignin with a pH of 8.5 with the activated protein, and the alkali solution uses a sodium hydroxide solution.

[0057] Meanwhile, the energy additives include a thickener and an antibacterial agent, wherein the thickener is a water-based thickening resin and cellulose nanocrystals with a mass ratio of 1, and the antibacterial agent is an inorganic antibacterial agent.

[0058] Amino resin crosslinker is Among them, Y1 is a methane group in which two chloro groups are substituted for hydrogen groups, Y3 is a methane group in which one hydroxyl group and one isocyanate group are substituted for hydrogen groups, Y2 is a pentyl group, and Y4 is a methane group.

[0059] Embodiment 4

[0060] A method for preparing a particleboard lignin-based biomass formaldehyde-free adhesive comprises the following steps:

[0061] Step 1, mixing animal collagen with inorganic alkali and subjecting them to ultrasonic treatment to obtain activated protein;

[0062] Step 2, the modified activated lignin, activated protein and amino resin cross-linking agent are mixed and stirred at a mass ratio of 43:19:11 for 16 minutes, and the stirring temperature is controlled at 39° C. to obtain a formaldehyde-free adhesive raw material;

[0063] Step 3: Add functional additives to the initial material of formaldehyde-free adhesive, control the mass ratio of functional additives to the initial material of formaldehyde-free adhesive to be 2:98, microwave heat treatment and stirring to obtain functional formaldehyde-free adhesive, and control the heat treatment temperature to 42°C, continue low-speed stirring for 0.3h, and the low-speed stirring speed is 70r / min.

[0064] Among them, the modified activated lignin is obtained by dissolving alkali lignin or lignin sulfonate in an ethanol solution, and then mixing with an activator and ultrasonic treatment, and the mass ratio of alkali lignin or lignin sulfonate to the activator is controlled to be 3:16, and the temperature is 45°C. The activator is obtained by mixing sulfuric acid with 3,3′-thiobis-1-propylene, and the pH of the activator is 3.0. It should be noted that after the modified activated lignin is mixed with the activator and ultrasonic treatment, an alkali solution is also used to adjust the pH to 7.3 for standby use, which is suitable for mixing and cross-linking the modified activated lignin with a pH of 7.3 with the activated protein, and the alkali solution uses a sodium hydroxide solution.

[0065] Meanwhile, the energy additives include a tackifier and an antibacterial agent. Among them, the tackifier is a water-based tackifier resin. The antibacterial agent is a quaternary ammonium salt antibacterial agent. Meanwhile, the amino resin crosslinking agent is a n-butyl etherified melamine resin.

[0066] Embodiment 5

[0067] The difference between Example 5 and Example 4 is that the amino resin cross-linking agent in Example 5 is a partially methylated melamine resin.

[0068] Embodiment 6

[0069] The difference between Example 6 and Example 4 is that the amino resin cross-linking agent in Example 6 is a high-imino resin.

[0070] Comparative Example 1

[0071] The difference between Comparative Example 1 and Example 3 is that the amino resin cross-linking agent in Comparative Example 1 is melamine bridging agent 995 purchased from Shaoxing Oucheng Chemical Co., Ltd.

[0072] Comparative Example 2

[0073] The difference between Comparative Example 2 and Example 3 is that no activated protein is added in the preparation of the aldehyde-free adhesive raw material in Comparative Example 2.

[0074] Comparative Example 3

[0075] The difference between Comparative Example 3 and Example 3 is that in Comparative Example 3, no 3,3′-thiobis-1-propylene is added to the activating agent used in the preparation of the modified activated lignin.

[0076] Performance Test:

[0077] The particleboard lignin-based biomass formaldehyde-free adhesive prepared by the preparation methods of the above-mentioned Examples 1 to 6 and Comparative Examples 1 to 3 is glued according to the particleboard cold pressing composite process to form an 8-layer laminate structure after curing, and the particleboard laminate thickness is controlled to be 12 mm, and the glue coating amount is 220 g / m 2 , 300g / m 2 and 420g / m 2 .

[0078] 1. Use GB / T 14074-2017 to test bonding strength;

[0079] 2. Use GB / T 14074-2017 to detect free formaldehyde content;

[0080] 3. Use GB / T 14074-2017 to test static bending strength.

[0081] Table 1 Performance test results

[0082]

[0083] As shown in Table 1 above, the particleboard lignin-based biomass formaldehyde-free adhesive prepared by the preparation method of the present application has the green and environmentally friendly effects of high static bending strength, high bonding strength and no formaldehyde release, and achieves the purpose of no free formaldehyde content when the amino resin cross-linking agent of the present application is used. At the same time, the test on water boiling resistance shows that the corresponding particleboard has the effect of no debonding when boiled in water at a high temperature of 100°C for 4-8h. Therefore, the particleboard lignin-based biomass formaldehyde-free adhesive has the effects of significantly improving water resistance, no free formaldehyde content, and high bonding strength, achieving the purpose of environmental protection.

[0084] In summary, the present application provides a method for preparing a particleboard lignin-based biomass formaldehyde-free adhesive, which is a method for preparing a particleboard lignin-based biomass formaldehyde-free adhesive. The method for preparing the particleboard lignin-based biomass formaldehyde-free adhesive is to activate animal collagen by inorganic alkali, so that the amino, hydroxyl and side chain groups in the activated protein are activated, and then the activated protein and the modified activated lignin are under the action of an amino resin cross-linking agent to form a cross-linked grid structure with a stable structure, thereby significantly improving the bonding strength of the particleboard lignin-based biomass formaldehyde-free adhesive obtained by the preparation method. Among them, the activator activates the lignin to obtain the corresponding modified activated lignin, so that the modified activated lignin is green and environmentally friendly to avoid formaldehyde release, and the surface active groups in the modified activated lignin and the activated protein are formed under the action of an amino resin cross-linking agent. The cross-linked grid structure with a stable structure, thereby significantly improving the bonding strength of the particleboard lignin-based biomass formaldehyde-free adhesive obtained by the preparation method, and the glue application opening time is extended during use, avoiding the problem of high difficulty in use due to high annual and short opening time, thereby significantly improving practicality. At the same time, the amino resin cross-linking agent has the effect of effectively improving the cross-linking curing activated protein and the modified activated lignin, thereby achieving the purpose of significantly improving the bonding strength while being formaldehyde-free and environmentally friendly, and by adding functional additives, the obtained functional formaldehyde-free adhesive has corresponding anti-curing, high viscosity and / or antibacterial effects, thereby significantly improving the usability and use effect of the functional formaldehyde-free adhesive.

[0085] The "first", "second", "third", "fourth", etc. (if any) referred to in this application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments described herein can be implemented in an order other than that described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods or devices.

[0086] It should be noted that the descriptions involving "first", "second", etc. in this application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0087] Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A method for preparing a particleboard lignin-based biomass formaldehyde-free adhesive, characterized in that: The steps include: Step 1, mixing animal collagen with inorganic alkali and subjecting them to ultrasonic treatment to obtain activated protein; Step 2, mixing the modified activated lignin with the activated protein and the amino resin cross-linking agent in a mass ratio of 42-50:17-23:5-20 for 10-30 minutes, controlling the stirring temperature to 30-45° C., to obtain a formaldehyde-free adhesive raw material; Step 3: Add the functional additives into the initial material of the formaldehyde-free adhesive, heat treat and stir to obtain the functional formaldehyde-free adhesive.

2. The method for preparing a particleboard lignin-based biomass formaldehyde-free adhesive according to claim 1, characterized in that: The modified activated lignin is obtained by dissolving lignin in an ethanol solution, mixing it with an activator and subjecting it to ultrasonic treatment. The mass ratio of the lignin to the activator is controlled to be 10-30:15-190, and the temperature is 15-45°C.

3. The method for preparing a particleboard lignin-based biomass formaldehyde-free adhesive according to claim 2, characterized in that: The activator is obtained by mixing sulfuric acid or phosphoric acid with 3,3'-thiobis-1-propylene, and the pH of the activator is ≥3.

0.

4. The method for preparing a particleboard lignin-based biomass formaldehyde-free adhesive according to claim 3, characterized in that: After the modified activated lignin is mixed with the activator and subjected to ultrasonic treatment, an alkali solution is used to adjust the pH to 7.0-8.

5.

5. The method for preparing a particleboard lignin-based biomass formaldehyde-free adhesive according to claim 1, characterized in that: The lignin is alkali lignin or lignin sulfonate.

6. The method for preparing a particleboard lignin-based biomass formaldehyde-free adhesive according to claim 1, characterized in that: The functional additives include at least one of a water retaining agent, a thickening agent and an antibacterial agent; the water retaining agent is at least one of ammonium polyacrylate, sodium alginate, hydroxypropyl methylcellulose and gelatin; the thickening agent is at least one of an aqueous thickening resin, cellulose nanocrystals, and copolymer ammonium salts; the antibacterial agent is at least one of an inorganic antibacterial agent, an imidazole antibacterial agent, a quaternary ammonium salt antibacterial agent, and a phenolic antibacterial agent.

7. The method for preparing a particleboard lignin-based biomass formaldehyde-free adhesive according to claim 1, characterized in that: The mass ratio of the functional additive to the formaldehyde-free adhesive initial material is 0-3:97-100.

8. The method for preparing a particleboard lignin-based biomass formaldehyde-free adhesive according to claim 1, characterized in that: The heat treatment adopts microwave heat treatment, and the heat treatment temperature is controlled to be 40-50° C., low-speed stirring is continued for 0.2-0.8 h, and the low-speed stirring speed is 60-180 r / min.

9. The method for preparing a particleboard lignin-based biomass formaldehyde-free adhesive according to claim 1, characterized in that: The amino resin crosslinking agent is Wherein, Y1 and Y3 are independently C1-C3 alkyl or silyl groups, wherein the hydrogen group is replaced by at least one halogen, carboxyl, hydroxyl, amino, aldehyde, mercapto, cyano, sulfonic acid, epoxy, anhydride, acyl chloride, acrylamide or isocyanate group; Y2 is C1-C6 alkyl; Y4 is a methyl group or an ethyl group.

10. The method for preparing a particleboard lignin-based biomass formaldehyde-free adhesive according to claim 1, characterized in that: The amino resin cross-linking agent is n-butyl etherified melamine resin, partially methyl etherified melamine resin or high imino resin.

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