A modified phenol-formaldehyde resin adhesive and a method for preparing the same

Abstract

This invention relates to the field of adhesive processing technology, specifically disclosing a modified phenolic resin adhesive and its preparation method. The method for preparing the modified phenolic resin adhesive includes: dispersing acid-treated carbon fibers in ethanol, adding a coupling agent, and stirring to obtain a carbon fiber dispersion; adding lignin, the carbon fiber dispersion, and Lewis acid to a mixed solvent, stirring, filtering, washing, and drying to obtain a functional filler; adding formaldehyde aqueous solution in batches to melamine, phenol, the functional filler, sodium hydroxide, and tetrahydrofuran, stirring at 80-90°C, and then treating to obtain a modified phenolic resin; mixing the modified phenolic resin, diluent, antibacterial agent, plasticizer, and deionized water to obtain a modified phenolic resin adhesive. The method provided by this invention reduces the use of raw material phenol, and the prepared phenolic resin adhesive has a low free formaldehyde content, meeting national green environmental protection requirements, high adhesive viscosity, and good heat resistance.

Description

Technical Field

[0001] This invention relates to the field of adhesive preparation technology, and more specifically, to a modified phenolic resin adhesive and its preparation method. Background Technology

[0002] Phenolic resin adhesives are essential auxiliary materials in many processes and are widely used in packaging, transportation, construction, manufacturing, healthcare, and renewable energy. They possess advantages such as wear resistance, water resistance, heat resistance, and good bonding properties. They are generally formed by the condensation polymerization of phenolic compounds such as phenol, resorcinol, cresol, and bisphenol A with aldehyde compounds such as formaldehyde, paraformaldehyde, furfural, and glyoxal. Despite their excellent performance, phenolic resin adhesives have poor toughness and are brittle. They are prone to cracking or breaking under impact or bending, and cannot effectively absorb and disperse stress. Furthermore, phenolic resin adhesives release toxic volatile molecules such as formaldehyde and phenol during the curing process. These substances not only pollute the environment but may also cause health problems. Therefore, seeking a widely available, low-cost, and environmentally friendly biomass polyphenol material to replace toxic petroleum-based phenol for the preparation of high-performance, low-cost, and environmentally friendly modified phenolic resin wood adhesives has become an important development trend.

[0003] Among numerous biomass resources, lignin is second only to cellulose in abundance and is the only biomass resource in nature capable of providing aromatic groups. Furthermore, it is inexpensive and biodegradable. However, lignin's large molecular weight and high dispersion, coupled with the fact that many of the ortho- and ortho-positioned phenolic hydroxyl groups in its structure that react with formaldehyde are replaced by methoxy groups, resulting in low reactivity, limit its large-scale application in phenolic resin adhesive production. Therefore, to vigorously develop the industrial application of lignin in phenolic resin adhesive production, lignin must be modified and activated. Currently, commonly used modification methods include amination, oxidation, and phenolation. However, each has its drawbacks: amination may involve toxic or volatile amines, posing risks to the environment and health; oxidative modification conditions easily lead to excessive degradation of lignin, affecting its thermal stability and mechanical properties; and phenolation modification requires high temperature and pressure, resulting in high energy consumption and the potential generation of byproducts that affect the purity of the final product. Therefore, given the limitations of the above-mentioned modified lignin in the preparation of phenolic resin adhesives, finding more effective and milder reaction conditions and developing environmentally friendly modified phenolic resin adhesives is a significant challenge facing the field of environmental science. Summary of the Invention

[0004] To address the above problems, this invention provides a modified phenolic resin adhesive and its preparation method.

[0005] In a first aspect, the present invention provides a method for preparing a modified phenolic resin adhesive, employing the following technical solution:

[0006] A method for preparing a modified phenolic resin adhesive includes the following preparation steps:

[0007] S1. Disperse the carbon fibers treated with organic acid in industrial ethanol, add a coupling agent, and stir evenly at room temperature to obtain a carbon fiber dispersion; add lignin, carbon fiber dispersion and Lewis acid to the mixed solvent, and stir continuously at 60-75℃ for 4-6 hours to make the mixture evenly dispersed, filter, wash and dry to obtain the functional filler.

[0008] S2. Dissolve phenol in tetrahydrofuran, add melamine, sodium hydroxide and functional filler to phenol-tetrahydrofuran, stir continuously at 80-90℃ for 1-3h, add the first batch of 37% formaldehyde aqueous solution, stir continuously at 80-90℃ for 1-3h and add the second batch of 37% formaldehyde aqueous solution, after the reaction is completed, distill under reduced pressure to obtain modified phenolic resin.

[0009] S3. The modified phenolic resin, antibacterial agent, diluent, plasticizer and deionized water are mixed to obtain the modified phenolic resin adhesive.

[0010] Preferably, the coupling agent in step S1 is composed of γ-aminopropyltrimethoxysilane and isopropyl triisostearate titanate in a mass ratio of 16-20:1.

[0011] Preferably, the mixed solvent in step S1 consists of 2-p-chlorobenzylpyridine, 1-butyl-3-methylimidazolium chloride, and fumaric acid in a molar ratio of 8-12:1-3:1-3.

[0012] Preferably, the Lewis acid in step S1 is any one of ferric chloride, aluminum chloride, or aluminum oxide.

[0013] Preferably, step S2 comprises, by weight, 14-18 parts phenol, 6-10 parts functional filler, 2-6 parts melamine, 1-3 parts sodium hydroxide, 34-38 parts 37% formaldehyde aqueous solution, and 80-100 parts tetrahydrofuran.

[0014] Preferably, in step S3, the components by weight are 40-44 parts modified phenolic resin, 16-20 parts diluent, 1-3 parts plasticizer, 1-3 parts antibacterial agent, and 80-100 parts deionized water.

[0015] Preferably, the diluent in step S3 is at least one of isopropanol, ethanol, and ethylene glycol.

[0016] Preferably, the antibacterial agent in step S3 is prepared by the following method:

[0017] (1) Add citric acid and hydroquinone to a silver nitrate solution with a concentration of 0.01-0.1 M, stir evenly, heat to 60-80℃, keep warm and stir for 20-40 min to obtain a silver solution;

[0018] (2) Chitosan powder is added to deionized water to prepare a chitosan solution with a mass concentration of 11-15%. Geraniol and silver solution are added sequentially while stirring. After stirring evenly, the pH is adjusted to 6.0-7.0. After standing for 3-5 hours, the solution is filtered and dried to obtain the antibacterial agent.

[0019] Preferably, the plasticizer in step S3 is at least one of dioctyl phthalate, triphenyl phosphate, and dipentaerythritol ester.

[0020] Secondly, this application also provides a modified phenolic resin adhesive, which adopts the following technical solution:

[0021] A modified phenolic resin adhesive is prepared by the above-described preparation method.

[0022] In summary, the present invention has the following beneficial effects:

[0023] 1. In the preparation of modified phenolic resin adhesives, the functional filler made by adding lignin to the treated carbon fiber dispersion can play multiple roles: First, as a natural polymer, lignin can enhance the mechanical properties and thermal stability of the resin matrix; second, through good bonding with carbon fibers, it helps to form a more uniform composite material structure and improve the overall mechanical properties; in addition, the presence of lignin can also improve the processing performance of the resin and endow the material with certain environmental protection properties. At the same time, lignin reduces the use of phenol for natural aromatic polymers.

[0024] 2. This invention uses a mixture of γ-aminopropyltrimethoxysilane and isopropyl triisostearate titanate to formulate a coupling agent. γ-aminopropyltrimethoxysilane reacts with the hydroxyl groups on the carbon fiber surface to form covalent bonds, and also reacts with hydroxyl groups or other functional groups in the phenolic resin matrix, thereby establishing a strong chemical bond between the carbon fiber and the resin, enhancing the interfacial bonding force. Isopropyl triisostearate titanate, as another coupling agent, further promotes the dispersion of carbon fibers in the resin matrix and prevents carbon fiber agglomeration, thus ensuring that the composite material has a good microstructure and uniformity. The synergistic effect of the two coupling agents not only enhances the interfacial adhesion but also improves the overall mechanical properties of the material.

[0025] 3. The mixed solvent of this invention is prepared by mixing 1-butyl-3-methylimidazolium chloride, fumaric acid, and 2-p-chlorobenzylpyridine. 1-Butyl-3-methylimidazolium chloride, as an ionic liquid, has excellent dissolving power, effectively dissolving lignin and also aiding in the dispersion of carbon fibers, thus ensuring uniform mixing of the components in subsequent processing. Fumaric acid and 2-p-chlorobenzylpyridine not only act as solvents to aid dissolution but also, to some extent, act as catalysts, promoting the modification reaction of lignin and helping to enhance the reactivity between lignin and other components, thereby improving the performance of the final product. By adjusting the ratio of the mixed solvent, an effective modification reaction can be achieved under relatively mild conditions (e.g., 60-75℃), avoiding excessive degradation or other side reactions caused by high temperature and high pressure. The added Lewis aldehyde can activate the functional groups on the surfaces of lignin and carbon fibers, promoting their cross-linking reaction.

[0026] 4. Adding a 37% formaldehyde aqueous solution in batches during the preparation of phenolic resin allows for controlled, gradual formaldehyde release, helps balance the reaction rate, and prevents excessively vigorous reactions caused by adding a large amount of formaldehyde at once. This allows for better control of the resin's crosslinking degree and molecular weight distribution. More importantly, adding formaldehyde in batches improves formaldehyde utilization, reduces unreacted free formaldehyde content, and lowers free formaldehyde emissions, thus meeting environmental protection requirements. Simultaneously added melamine acts as a comonomer in resin synthesis; its six-membered ring structure contains multiple active amino groups that can crosslink with formaldehyde, enhancing the resin's heat resistance and mechanical properties. Because melamine participates in the reaction, it consumes more formaldehyde, further reducing the free formaldehyde content in the final product, making the resulting modified phenolic resin more environmentally friendly.

[0027] 5. The antibacterial agent in this invention is prepared by adding silver nitrate, citric acid, hydroquinone, and geraniol together to a chitosan solution. Silver nitrate and hydroquinone have antibacterial properties, while citric acid acts as a buffer to help maintain the pH stability of the solution, thereby improving the effectiveness of the antibacterial agent. Geraniol, as a naturally sourced antibacterial agent, enhances the antibacterial properties through synergistic effects with chitosan. The addition of this antibacterial agent not only protects the modified phenolic resin adhesive from microbial contamination but also imparts certain antibacterial functions to the finished product, making it particularly suitable for applications with high hygiene requirements. The plasticizer molecules added along with the antibacterial agent can insert into the molecular chains of the phenolic resin, weakening the intermolecular attraction and thus lowering the glass transition temperature of the material, enhancing its elasticity and impact resistance. This not only makes the phenolic resin easier to process and mold but also improves the durability and service life of the final product. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the experimental materials used, unless otherwise specified, were all purchased from conventional biochemical reagent stores. All quantitative experiments in the following examples were performed in triplicate, and the data are the average of the three replicates or the average ± standard deviation.

[0030] Preparation Example 1

[0031] The antibacterial agent is prepared by the following method:

[0032] (1) Add citric acid and hydroquinone to a 0.01M silver nitrate solution, control the stirring speed to 300r / min, stir for 40min until uniform, heat to 60℃, keep warm and stir for 40min to obtain silver solution; wherein, the mass ratio of silver nitrate solution, citric acid and hydroquinone is 12:1:1;

[0033] (2) Chitosan powder was added to deionized water to prepare a chitosan solution with a mass concentration of 11%. Geraniol and silver solution were added sequentially while stirring. After stirring evenly, the pH was adjusted to 6.0. After standing for 3 hours, the solution was filtered and dried to obtain the antibacterial agent. The mass ratio of chitosan solution, geraniol and silver solution was 30:1:8.

[0034] Preparation Example 2

[0035] The antibacterial agent is prepared by the following method:

[0036] (1) Add citric acid and hydroquinone to a 0.05M silver nitrate solution, control the stirring speed to 400r / min, stir for 30min until uniform, heat to 70℃, keep warm and stir for 30min to obtain silver solution; wherein, the mass ratio of silver nitrate solution, citric acid and hydroquinone is 14:2:1;

[0037] (2) Chitosan powder was added to deionized water to prepare a chitosan solution with a mass concentration of 13%. Geraniol and silver solution were added sequentially while stirring. After stirring evenly, the pH was adjusted to 6.5. After standing for 4 hours, the solution was filtered and dried to obtain the antibacterial agent. The mass ratio of chitosan solution, geraniol and silver solution was 31:2:9.

[0038] Preparation Example 3

[0039] The antibacterial agent is prepared by the following method:

[0040] (1) Add citric acid and hydroquinone to a 0.1 M silver nitrate solution, control the stirring speed to 500 r / min, stir for 20 min until uniform, heat to 80 °C, keep warm and stir for 20 min to obtain silver solution; wherein, the mass ratio of silver nitrate solution, citric acid and hydroquinone is 15:3:3;

[0041] (2) Chitosan powder was added to deionized water to prepare a chitosan solution with a mass concentration of 15%. Geraniol and silver solution were added sequentially while stirring. After stirring evenly, the pH was adjusted to 7.0. After standing for 5 hours, the solution was filtered and dried to obtain the antibacterial agent. The mass ratio of chitosan solution, geraniol and silver solution was 34:2:10.

[0042] Comparative Preparation Example 1

[0043] The antibacterial agent is prepared by the following method:

[0044] (1) Add citric acid to a 0.01M silver nitrate solution, control the stirring speed to 300r / min, stir for 40min until uniform, heat to 60℃, keep warm and stir for 40min to obtain silver solution; wherein, the mass ratio of silver nitrate solution, citric acid and hydroquinone is 12:2;

[0045] (2) Chitosan powder was added to deionized water to prepare a chitosan solution with a mass concentration of 11%. Geraniol and silver solution were added sequentially while stirring. After stirring evenly, the pH was adjusted to 6.0. After standing for 3 hours, the solution was filtered and dried to obtain the antibacterial agent. The mass ratio of chitosan solution, geraniol and silver solution was 30:1:8.

[0046] Comparative Preparation Example 2

[0047] The antibacterial agent is prepared by the following method:

[0048] (1) Add citric acid and hydroquinone to a 0.01M silver nitrate solution, control the stirring speed to 300r / min, stir for 40min until uniform, heat to 60℃, keep warm and stir for 40min to obtain silver solution; wherein, the mass ratio of silver nitrate solution, citric acid and hydroquinone is 12:1:1;

[0049] (2) Chitosan powder was added to deionized water to prepare a chitosan solution with a mass concentration of 11%. Silver solution was added sequentially while stirring. After stirring evenly, the pH was adjusted to 6.0. After standing for 3 hours, the solution was filtered and dried to obtain the antibacterial agent. The mass ratio of chitosan solution to silver solution was 30:8.

[0050] Example 1

[0051] A method for preparing a modified phenolic resin adhesive, specifically including the following preparation steps:

[0052] S1: Carbon fibers are added to acetic acid and soaked at 60°C for 3 hours. After repeated washing until neutral, the carbon fibers are dried to obtain pretreated carbon fibers for later use. The mass ratio of carbon fibers to acetic acid is 1:8. The pretreated carbon fibers are dispersed in industrial ethanol, and a coupling agent is added. The mass ratio of industrial ethanol, pretreated carbon fibers, and coupling agent is 100:28:4. The coupling agent consists of γ-aminopropyltrimethoxysilane and isopropyl triisostearate titanate in a mass ratio of 16:1. The mixture is stirred evenly at room temperature until a stable carbon fiber dispersion is formed. 2-p-chlorobenzylpyridine, 1-butyl-3-methylimidazolium chloride, and fumaric acid are prepared into a mixed solvent according to a molar ratio of 8:1:1. Lignin, carbon fiber dispersion, and ferric chloride are added to the mixed solvent. The mass ratio of the mixed solvent, lignin, carbon fiber dispersion, and ferric chloride is 100:20:10:1. The mixture is stirred continuously at 60°C for 6 hours to ensure uniform dispersion. After filtration, washing, and drying, the functional filler is obtained.

[0053] S2: By weight, 14 parts phenol, 6 parts functional filler, 2 parts melamine, 1 part sodium hydroxide and 17 parts 37% formaldehyde aqueous solution are added to 80 parts tetrahydrofuran. After stirring continuously at 80°C for 3 hours, another 17 parts 37% formaldehyde aqueous solution are added to the reaction system, and stirring is continued at 80°C for 3 hours. After the reaction is completed, the modified phenolic resin is obtained by vacuum distillation.

[0054] S3: Weigh 40 parts by weight of modified phenolic resin, 16 parts by weight of isopropanol, 1 part by weight of dioctyl phthalate, 1 part by weight of the antibacterial agent prepared in Example 1, and 80 parts by weight of deionized water to obtain modified phenolic resin adhesive.

[0055] Example 2

[0056] A method for preparing a modified phenolic resin adhesive, specifically including the following preparation steps:

[0057] S1: Carbon fibers are added to acetic acid and soaked at 63°C for 2.8 hours. After repeated washing until neutral, the carbon fibers are dried to obtain pretreated carbon fibers for later use. The mass ratio of carbon fibers to acetic acid is 1:9. The pretreated carbon fibers are dispersed in industrial ethanol, and a coupling agent is added. The mass ratio of industrial ethanol, pretreated carbon fibers, and coupling agent is 100:29:5. The coupling agent consists of γ-aminopropyltrimethoxysilane and isopropyl triisostearate titanate in a mass ratio of 17:1. The mixture is stirred evenly at room temperature until a stable carbon fiber dispersion is formed. 2-p-chlorobenzylpyridine, 1-butyl-3-methylimidazolium chloride, and fumaric acid are prepared into a mixed solvent according to a molar ratio of 9:2:1. Lignin, carbon fiber dispersion, and ferric chloride are added to the mixed solvent. The mass ratio of the mixed solvent, lignin, carbon fiber dispersion, and ferric chloride is 100:22:11:1. The mixture is stirred continuously at 65°C for 5.5 hours to ensure uniform dispersion. After filtration, washing, and drying, the functional filler is obtained.

[0058] S2: By weight, 15 parts phenol, 7 parts functional filler, 3 parts melamine, 1.5 parts sodium hydroxide and 18 parts 37% formaldehyde aqueous solution are added to 80-100 parts tetrahydrofuran. After stirring at 85°C for 2 hours, another 18 parts 37% formaldehyde aqueous solution are added to the reaction system, and stirring is continued at 85°C for 2 hours. After the reaction is completed, the modified phenolic resin is obtained by vacuum distillation.

[0059] S3: Weigh 42 parts of modified phenolic resin, 17 parts of isopropanol, 2 parts of dioctyl phthalate, 2 parts of the antibacterial agent prepared in Preparation Example 2, and 85 parts of deionized water by weight to obtain modified phenolic resin adhesive.

[0060] Example 3

[0061] A method for preparing a modified phenolic resin adhesive, specifically including the following preparation steps:

[0062] S1: Carbon fibers are added to acetic acid and soaked at 65°C for 2.5 hours. After repeated washing until neutral, the carbon fibers are dried to obtain pretreated carbon fibers for later use. The mass ratio of carbon fibers to acetic acid is 1:9. The pretreated carbon fibers are dispersed in industrial ethanol, and a coupling agent is added. The mass ratio of industrial ethanol, pretreated carbon fibers, and coupling agent is 100:30:6. The coupling agent consists of γ-aminopropyltrimethoxysilane and isopropyl triisostearate titanate in a mass ratio of 18:1. The mixture is stirred evenly at room temperature until a stable carbon fiber dispersion is formed. 2-p-chlorobenzylpyridine, 1-butyl-3-methylimidazolium chloride, and fumaric acid are prepared into a mixed solvent according to a molar ratio of 10:2:2. Lignin, carbon fiber dispersion, and ferric chloride are added to the mixed solvent. The mass ratio of the mixed solvent, lignin, carbon fiber dispersion, and ferric chloride is 100:22:11:1. The mixture is stirred continuously at 68°C for 5 hours to ensure uniform dispersion. After filtration, washing, and drying, the functional filler is obtained.

[0063] S2: By weight, 16 parts phenol, 8 parts functional filler, 4 parts melamine, 2 parts sodium hydroxide and 18 parts 37% formaldehyde aqueous solution are added to 90 parts tetrahydrofuran. After stirring at 85°C for 2 hours, 17-19 parts 37% formaldehyde aqueous solution are added to the reaction system and stirring is continued at 85°C for 2 hours. After the reaction is completed, the modified phenolic resin is obtained by vacuum distillation.

[0064] S3: Weigh 42 parts by weight of modified phenolic resin, 18 parts by weight of isopropanol, 2 parts by weight of dioctyl phthalate, 2 parts by weight of the antibacterial agent prepared in Example 2, and 90 parts by weight of deionized water to obtain modified phenolic resin adhesive.

[0065] Example 4

[0066] A method for preparing a modified phenolic resin adhesive, specifically including the following preparation steps:

[0067] S1: Carbon fibers are added to acetic acid and soaked at 70°C for 2 hours. After repeated washing until neutral, the carbon fibers are dried to obtain pretreated carbon fibers for later use. The mass ratio of carbon fibers to acetic acid is 1:10. The pretreated carbon fibers are dispersed in industrial ethanol, and a coupling agent is added. The mass ratio of industrial ethanol, pretreated carbon fibers, and coupling agent is 100:32:7. The coupling agent is composed of γ-aminopropyltrimethoxysilane and isopropyl triisostearate titanate in a mass ratio of 20:1. The mixture is stirred evenly at room temperature until a stable carbon fiber dispersion is formed. 2-p-chlorobenzylpyridine, 1-butyl-3-methylimidazolium chloride, and fumaric acid are prepared into a mixed solvent according to a molar ratio of 12:3:3. Lignin, carbon fiber dispersion, and ferric chloride are added to the mixed solvent. The mass ratio of the mixed solvent, lignin, carbon fiber dispersion, and ferric chloride is 100:24:12:1. The mixture is stirred continuously at 75°C for 4 hours to ensure uniform dispersion. After filtration, washing, and drying, the functional filler is obtained.

[0068] S2: By weight, 18 parts phenol, 10 parts functional filler, 6 parts melamine, 3 parts sodium hydroxide and 19 parts 37% formaldehyde aqueous solution are added to 100 parts tetrahydrofuran. After stirring at 90°C for 1 hour, another 19 parts 37% formaldehyde aqueous solution are added to the reaction system, and stirring is continued at 90°C for 1 hour. After the reaction is completed, the modified phenolic resin is obtained by vacuum distillation.

[0069] S3: Weigh 44 parts of modified phenolic resin, 20 parts of isopropanol, 3 parts of dioctyl phthalate, 3 parts of the antibacterial agent prepared in Preparation Example 3, and 100 parts of deionized water by weight to obtain modified phenolic resin adhesive.

[0070] Comparative Example 1

[0071] A method for preparing a modified phenolic resin adhesive, specifically including the following preparation steps:

[0072] S1: Add carbon fiber to acetic acid, soak at 60℃ for 3 hours, wash repeatedly until neutral, and dry to obtain pretreated carbon fiber for later use. The mass ratio of carbon fiber to acetic acid is 1:8. Disperse the pretreated carbon fiber in industrial ethanol, add γ-aminopropyltrimethoxysilane, wherein the mass ratio of industrial ethanol, pretreated carbon fiber, and γ-aminopropyltrimethoxysilane is 100:28:4. Stir the mixture at room temperature until a stable carbon fiber dispersion is formed. Prepare a mixed solvent by mixing 2-p-chlorobenzylpyridine, 1-butyl-3-methylimidazolium chloride, and fumaric acid in a molar ratio of 8:1:1. Add lignin, carbon fiber dispersion, and ferric chloride to the mixed solvent, wherein the mass ratio of the mixed solvent, lignin, carbon fiber dispersion, and ferric chloride is 100:20:10:1. Stir continuously at 60℃ for 6 hours to ensure uniform dispersion of the mixture. Filter, wash, and dry to obtain the functional filler.

[0073] S2: By weight, 14 parts phenol, 6 parts functional filler, 2 parts melamine, 1 part sodium hydroxide and 17 parts 37% formaldehyde aqueous solution are added to 80 parts tetrahydrofuran. After stirring continuously at 80°C for 3 hours, another 17 parts 37% formaldehyde aqueous solution are added to the reaction system, and stirring is continued at 80°C for 3 hours. After the reaction is completed, the modified phenolic resin is obtained by vacuum distillation.

[0074] S3: Weigh 40 parts by weight of modified phenolic resin, 16 parts by weight of isopropanol, 1 part by weight of dioctyl phthalate, 1 part by weight of antibacterial agent and 80 parts by weight of deionized water and mix them to obtain modified phenolic resin adhesive.

[0075] Comparative Example 2

[0076] A method for preparing a modified phenolic resin adhesive, specifically including the following preparation steps:

[0077] S1: Carbon fibers are added to acetic acid and soaked at 60°C for 3 hours. After repeated washing until neutral, the carbon fibers are dried to obtain pretreated carbon fibers for later use. The mass ratio of carbon fibers to acetic acid is 1:8. The pretreated carbon fibers are dispersed in industrial ethanol, and triisostearate isopropyl titanate is added. The mass ratio of industrial ethanol, pretreated carbon fibers, and triisostearate isopropyl titanate is 100:28:4. The mixture is stirred evenly at room temperature until a stable carbon fiber dispersion is formed. 2-p-chlorobenzylpyridine, 1-butyl-3-methylimidazolium chloride, and fumaric acid are prepared into a mixed solvent according to a molar ratio of 8:1:1. Lignin, carbon fiber dispersion, and ferric chloride are added to the mixed solvent. The mass ratio of the mixed solvent, lignin, carbon fiber dispersion, and ferric chloride is 100:20:10:1. The mixture is stirred continuously at 60°C for 6 hours to ensure uniform dispersion. After filtration, washing, and drying, the functional filler is obtained.

[0078] S2: By weight, 14 parts phenol, 6 parts functional filler, 2 parts melamine, 1 part sodium hydroxide and 17 parts 37% formaldehyde aqueous solution are added to 80 parts tetrahydrofuran. After stirring continuously at 80°C for 3 hours, another 17 parts 37% formaldehyde aqueous solution are added to the reaction system, and stirring is continued at 80°C for 3 hours. After the reaction is completed, the modified phenolic resin is obtained by vacuum distillation.

[0079] S3: Weigh 40 parts by weight of modified phenolic resin, 16 parts by weight of isopropanol, 1 part by weight of dioctyl phthalate, 1 part by weight of antibacterial agent and 80 parts by weight of deionized water and mix them to obtain modified phenolic resin adhesive.

[0080] Comparative Example 3

[0081] A method for preparing a modified phenolic resin adhesive, specifically including the following preparation steps:

[0082] S1: Carbon fibers are added to acetic acid and soaked at 60°C for 3 hours. After repeated washing until neutral, the carbon fibers are dried to obtain pretreated carbon fibers for later use. The mass ratio of carbon fibers to acetic acid is 1:8. The pretreated carbon fibers are dispersed in industrial ethanol, and a coupling agent is added. The mass ratio of industrial ethanol, pretreated carbon fibers, and coupling agent is 100:28:4. The coupling agent consists of isopropyl triisostearate titanate and γ-aminopropyltrimethoxysilane in a mass ratio of 16:1. The mixture is stirred evenly at room temperature until a stable carbon fiber dispersion is formed. 2-p-chlorobenzylpyridine, 1-butyl-3-methylimidazolium chloride, and fumaric acid are prepared into a mixed solvent according to a molar ratio of 8:1:1. Lignin, carbon fiber dispersion, and ferric chloride are added to the mixed solvent. The mass ratio of the mixed solvent, lignin, carbon fiber dispersion, and ferric chloride is 100:20:10:1. The mixture is stirred continuously at 60°C for 6 hours to ensure uniform dispersion. After filtration, washing, and drying, the functional filler is obtained.

[0083] S2: By weight, 14 parts phenol, 6 parts functional filler, 2 parts melamine, 1 part sodium hydroxide and 17 parts 37% formaldehyde aqueous solution are added to 80 parts tetrahydrofuran. After stirring continuously at 80°C for 3 hours, another 17 parts 37% formaldehyde aqueous solution are added to the reaction system, and stirring is continued at 80°C for 3 hours. After the reaction is completed, the modified phenolic resin is obtained by vacuum distillation.

[0084] S3: Weigh 40 parts by weight of modified phenolic resin, 16 parts by weight of isopropanol, 1 part by weight of dioctyl phthalate, 1 part by weight of antibacterial agent and 80 parts by weight of deionized water and mix them to obtain modified phenolic resin adhesive.

[0085] Comparative Example 4

[0086] A method for preparing a modified phenolic resin adhesive, specifically including the following preparation steps:

[0087] S1: Carbon fibers are added to acetic acid and soaked at 60°C for 3 hours. After repeated washing until neutral, the carbon fibers are dried to obtain pretreated carbon fibers for later use. The mass ratio of carbon fibers to acetic acid is 1:8. The pretreated carbon fibers are dispersed in industrial ethanol, and a coupling agent is added. The mass ratio of industrial ethanol, pretreated carbon fibers, and coupling agent is 100:28:4. The coupling agent is composed of γ-aminopropyltrimethoxysilane and isopropyl triisostearate titanate in a mass ratio of 16:1. The mixture is stirred evenly at room temperature until a stable carbon fiber dispersion is formed. 2-p-chlorobenzylpyridine and 1-butyl-3-methylimidazolium chloride are prepared as a solvent in a molar ratio of 8:1. Lignin, carbon fiber dispersion, and ferric chloride are added to the solvent. The mass ratio of 1-butyl-3-methylimidazolium chloride solvent, lignin, carbon fiber dispersion, and ferric chloride is 100:20:10:1. The mixture is stirred continuously at 60°C for 6 hours to ensure uniform dispersion. After filtration, washing, and drying, the functional filler is obtained.

[0088] S2: By weight, 14 parts phenol, 6 parts functional filler, 2 parts melamine, 1 part sodium hydroxide and 17 parts 37% formaldehyde aqueous solution are added to 80 parts tetrahydrofuran. After stirring continuously at 80°C for 3 hours, another 17 parts 37% formaldehyde aqueous solution are added to the reaction system, and stirring is continued at 80°C for 3 hours. After the reaction is completed, the modified phenolic resin is obtained by vacuum distillation.

[0089] S3: Weigh 40 parts by weight of modified phenolic resin, 16 parts by weight of isopropanol, 1 part by weight of dioctyl phthalate, 1 part by weight of antibacterial agent and 80 parts by weight of deionized water and mix them to obtain modified phenolic resin adhesive.

[0090] Comparative Example 5

[0091] A method for preparing a modified phenolic resin adhesive, specifically including the following preparation steps:

[0092] S1: Carbon fibers are added to acetic acid and soaked at 60°C for 3 hours. After repeated washing until neutral, the carbon fibers are dried to obtain pretreated carbon fibers for later use. The mass ratio of carbon fibers to acetic acid is 1:8. The pretreated carbon fibers are dispersed in industrial ethanol, and a coupling agent is added. The mass ratio of industrial ethanol, pretreated carbon fibers, and coupling agent is 100:28:4. The coupling agent consists of γ-aminopropyltrimethoxysilane and isopropyl triisostearate titanate in a mass ratio of 16:1. The mixture is stirred evenly at room temperature until a stable carbon fiber dispersion is formed. 2-p-chlorobenzylpyridine and fumaric acid are prepared into a mixed solvent at a molar ratio of 8:1. Lignin, carbon fiber dispersion, and ferric chloride are added to the mixed solvent. The mass ratio of the mixed solvent, lignin, carbon fiber dispersion, and ferric chloride is 100:20:10:1. The mixture is stirred continuously at 60°C for 6 hours to ensure uniform dispersion. After filtration, washing, and drying, the functional filler is obtained.

[0093] S2: By weight, 14 parts phenol, 6 parts functional filler, 2 parts melamine, 1 part sodium hydroxide and 17 parts 37% formaldehyde aqueous solution are added to 80 parts tetrahydrofuran. After stirring continuously at 80°C for 3 hours, another 17 parts 37% formaldehyde aqueous solution are added to the reaction system, and stirring is continued at 80°C for 3 hours. After the reaction is completed, the modified phenolic resin is obtained by vacuum distillation.

[0094] S3: Weigh 40 parts by weight of modified phenolic resin, 16 parts by weight of isopropanol, 1 part by weight of dioctyl phthalate, 1 part by weight of antibacterial agent and 80 parts by weight of deionized water and mix them to obtain modified phenolic resin adhesive.

[0095] Comparative Example 6

[0096] A method for preparing a modified phenolic resin adhesive, specifically including the following preparation steps:

[0097] S1: Carbon fibers are added to acetic acid and soaked at 60°C for 3 hours. After repeated washing until neutral, the carbon fibers are dried to obtain pretreated carbon fibers for later use. The mass ratio of carbon fibers to acetic acid is 1:8. The pretreated carbon fibers are dispersed in industrial ethanol, and a coupling agent is added. The mass ratio of industrial ethanol, pretreated carbon fibers, and coupling agent is 100:28:4. The coupling agent consists of γ-aminopropyltrimethoxysilane and isopropyl triisostearate titanate in a mass ratio of 16:1. The mixture is stirred evenly at room temperature until a stable carbon fiber dispersion is formed. Lignin, carbon fiber dispersion, and ferric chloride are added to N,N-dimethylformamide. The mass ratio of N,N-dimethylformamide, lignin, carbon fiber dispersion, and ferric chloride is 100:20:10:1. The mixture is stirred continuously at 60°C for 6 hours to ensure uniform dispersion. After filtration, washing, and drying, the functional filler is obtained.

[0098] S2: By weight, 14 parts phenol, 6 parts functional filler, 2 parts melamine, 1 part sodium hydroxide and 17 parts 37% formaldehyde aqueous solution are added to 80 parts tetrahydrofuran. After stirring continuously at 80°C for 3 hours, another 17 parts 37% formaldehyde aqueous solution are added to the reaction system, and stirring is continued at 80°C for 3 hours. After the reaction is completed, the modified phenolic resin is obtained by vacuum distillation.

[0099] S3: Weigh 40 parts by weight of modified phenolic resin, 16 parts by weight of isopropanol, 1 part by weight of dioctyl phthalate, 1 part by weight of antibacterial agent and 80 parts by weight of deionized water and mix them to obtain modified phenolic resin adhesive.

[0100] Comparative Example 7

[0101] A method for preparing a modified phenolic resin adhesive, specifically including the following preparation steps:

[0102] S1: Carbon fibers are added to acetic acid and soaked at 60°C for 3 hours. After repeated washing until neutral, the carbon fibers are dried to obtain pretreated carbon fibers for later use. The mass ratio of carbon fibers to acetic acid is 1:8. The pretreated carbon fibers are dispersed in industrial ethanol, and a coupling agent is added. The mass ratio of industrial ethanol, pretreated carbon fibers, and coupling agent is 100:28:4. The coupling agent consists of γ-aminopropyltrimethoxysilane and isopropyl triisostearate titanate in a mass ratio of 16:1. The mixture is stirred evenly at room temperature until a stable carbon fiber dispersion is formed. 2-p-chlorobenzylpyridine, 1-butyl-3-methylimidazolium chloride, and fumaric acid are prepared into a mixed solvent according to a molar ratio of 8:1:1. Lignin, carbon fiber dispersion, and ferric chloride are added to the mixed solvent. The mass ratio of the mixed solvent, lignin, carbon fiber dispersion, and ferric chloride is 100:20:10:1. The mixture is stirred continuously at 60°C for 6 hours to ensure uniform dispersion. After filtration, washing, and drying, the functional filler is obtained.

[0103] S2: By weight, 14 parts phenol, 6 parts functional filler, 2 parts melamine, 1 part sodium hydroxide and 34 parts 37% formaldehyde aqueous solution are added to 80 parts tetrahydrofuran. The mixture is stirred continuously at 80℃ for 6 hours. After the reaction is completed, the modified phenolic resin is obtained by vacuum distillation.

[0104] S3: Weigh 40 parts by weight of modified phenolic resin, 16 parts by weight of isopropanol, 1 part by weight of dioctyl phthalate, 1 part by weight of antibacterial agent and 80 parts by weight of deionized water and mix them to obtain modified phenolic resin adhesive.

[0105] Comparative Example 8

[0106] A method for preparing a modified phenolic resin adhesive, specifically including the following preparation steps:

[0107] S1: Carbon fibers are added to acetic acid and soaked at 60°C for 3 hours. After repeated washing until neutral, the carbon fibers are dried to obtain pretreated carbon fibers for later use. The mass ratio of carbon fibers to acetic acid is 1:8. The pretreated carbon fibers are dispersed in industrial ethanol, and a coupling agent is added. The mass ratio of industrial ethanol, pretreated carbon fibers, and coupling agent is 100:28:4. The coupling agent consists of γ-aminopropyltrimethoxysilane and isopropyl triisostearate titanate in a mass ratio of 16:1. The mixture is stirred evenly at room temperature until a stable carbon fiber dispersion is formed. 2-p-chlorobenzylpyridine, 1-butyl-3-methylimidazolium chloride, and fumaric acid are prepared into a mixed solvent according to a molar ratio of 8:1:1. Lignin and the carbon fiber dispersion are added to the mixed solvent. The mass ratio of the mixed solvent, lignin, and carbon fiber dispersion is 100:20:10. The mixture is stirred continuously at 60°C for 6 hours to ensure uniform dispersion. After filtration, washing, and drying, the functional filler is obtained.

[0108] S2: By weight, 14 parts phenol, 6 parts functional filler, 2 parts melamine, 1 part sodium hydroxide and 17 parts 37% formaldehyde aqueous solution are added to 80 parts tetrahydrofuran. After stirring continuously at 80°C for 3 hours, another 17 parts 37% formaldehyde aqueous solution are added to the reaction system, and stirring is continued at 80°C for 3 hours. After the reaction is completed, the modified phenolic resin is obtained by vacuum distillation.

[0109] S3: Weigh 40 parts by weight of modified phenolic resin, 16 parts by weight of isopropanol, 1 part by weight of dioctyl phthalate, 1 part by weight of antibacterial agent and 80 parts by weight of deionized water and mix them to obtain modified phenolic resin adhesive.

[0110] Comparative Example 9

[0111] A method for preparing a modified phenolic resin adhesive, specifically including the following preparation steps:

[0112] S1: Carbon fibers are added to acetic acid and soaked at 60°C for 3 hours. After repeated washing until neutral, the carbon fibers are dried to obtain pretreated carbon fibers for later use. The mass ratio of carbon fibers to acetic acid is 1:8. The pretreated carbon fibers are dispersed in industrial ethanol, and a coupling agent is added. The mass ratio of industrial ethanol, pretreated carbon fibers, and coupling agent is 100:28:4. The coupling agent consists of γ-aminopropyltrimethoxysilane and isopropyl triisostearate titanate in a mass ratio of 16:1. The mixture is stirred evenly at room temperature until a stable carbon fiber dispersion is formed. 2-p-chlorobenzylpyridine, 1-butyl-3-methylimidazolium chloride, and fumaric acid are prepared into a mixed solvent according to a molar ratio of 8:1:1. Lignin, carbon fiber dispersion, and ferric chloride are added to the mixed solvent. The mass ratio of the mixed solvent, lignin, carbon fiber dispersion, and ferric chloride is 100:20:10:1. The mixture is stirred continuously at 60°C for 6 hours to ensure uniform dispersion. After filtration, washing, and drying, the functional filler is obtained.

[0113] S2: By weight, 14 parts phenol, 6 parts functional filler, 2 parts melamine, 1 part sodium hydroxide and 17 parts 37% formaldehyde aqueous solution are added to 80 parts tetrahydrofuran. After stirring continuously at 80°C for 3 hours, another 17 parts 37% formaldehyde aqueous solution are added to the reaction system, and stirring is continued at 80°C for 3 hours. After the reaction is completed, the modified phenolic resin is obtained by vacuum distillation.

[0114] S3: Weigh 40 parts by weight of modified phenolic resin, 16 parts by weight of isopropanol, 1 part by weight of dioctyl phthalate, 1 part by weight of antibacterial agent prepared in Comparative Preparation Example 1, and 80 parts by weight of deionized water to obtain modified phenolic resin adhesive.

[0115] Comparative Example 10

[0116] A method for preparing a modified phenolic resin adhesive, specifically including the following preparation steps:

[0117] S1: Carbon fibers are added to acetic acid and soaked at 60°C for 3 hours. After repeated washing until neutral, the carbon fibers are dried to obtain pretreated carbon fibers for later use. The mass ratio of carbon fibers to acetic acid is 1:8. The pretreated carbon fibers are dispersed in industrial ethanol, and a coupling agent is added. The mass ratio of industrial ethanol, pretreated carbon fibers, and coupling agent is 100:28:4. The coupling agent consists of γ-aminopropyltrimethoxysilane and isopropyl triisostearate titanate in a mass ratio of 16:1. The mixture is stirred evenly at room temperature until a stable carbon fiber dispersion is formed. 2-p-chlorobenzylpyridine, 1-butyl-3-methylimidazolium chloride, and fumaric acid are prepared into a mixed solvent according to a molar ratio of 8:1:1. Lignin, carbon fiber dispersion, and ferric chloride are added to the mixed solvent. The mass ratio of the mixed solvent, lignin, carbon fiber dispersion, and ferric chloride is 100:20:10:1. The mixture is stirred continuously at 60°C for 6 hours to ensure uniform dispersion. After filtration, washing, and drying, the functional filler is obtained.

[0118] S2: By weight, 14 parts phenol, 6 parts functional filler, 2 parts melamine, 1 part sodium hydroxide and 17 parts 37% formaldehyde aqueous solution are added to 80 parts tetrahydrofuran. After stirring continuously at 80°C for 3 hours, another 17 parts 37% formaldehyde aqueous solution are added to the reaction system, and stirring is continued at 80°C for 3 hours. After the reaction is completed, the modified phenolic resin is obtained by vacuum distillation.

[0119] S3: Weigh 40 parts by weight of modified phenolic resin, 16 parts by weight of isopropanol, 1 part by weight of dioctyl phthalate, 1 part by weight of the antibacterial agent prepared in Comparative Preparation Example 2, and 80 parts by weight of deionized water to obtain modified phenolic resin adhesive.

[0120] Performance testing

[0121] The modified phenolic resin adhesive prepared in the above experiment was subjected to the following performance tests:

[0122] 1. Formaldehyde residue

[0123] The formaldehyde residue in the phenolic resin adhesives prepared in each example and comparative example was tested according to GB / T 32461-2015 "Determination of formaldehyde content in amino resins and phenolic resins and the amount of formaldehyde migration in molded products by high performance liquid chromatography". The test results are shown in Table 1.

[0124] The residual phenol content in the phenolic resin adhesives prepared in each example and comparative example was tested according to the method provided in HG / T 2621-1994 "Determination of Residual Phenol Content in Phenolic Resins by Gas Chromatography".

[0125] Mechanical property bonding strength test: The coating method in GB / T 17657-2013 was adopted. The adhesive was applied to the wood board and then treated. Finally, the test was carried out in the tensile shear test mode.

[0126] Impact strength of adhesive-coated plywood is tested according to GB / T 9846-2015 "Ordinary Plywood".

[0127] The test results are shown in Table 1.

[0128] The antibacterial properties were tested according to the requirements and procedures of the national standard GB / T 31402-2015, "Test Method for Antibacterial Properties of Plastic Surfaces," with Staphylococcus aureus and Escherichia coli being the tested bacteria. The antibacterial durability was tested according to the national standard GB / T 31402-2015. After the samples were placed for 90 days, the antibacterial rate was tested, and the test results are shown in Table 2.

[0129] Table 1. Overall performance of adhesives prepared in Examples 1-4 and Comparative Examples 1-10

[0130]

[0131] Table 2. Antibacterial properties of adhesives prepared in Examples 1-4 and Comparative Examples 9-10

[0132]

[0133] As shown in Tables 1 and 2 above, the modified phenolic resin adhesives prepared in Examples 1-4 of the present invention have a much better overall performance than comparative examples 1-10.

[0134] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A method for preparing a modified phenolic resin adhesive, characterized in that, The preparation steps include the following: S1. Disperse the carbon fibers treated with organic acid in industrial ethanol, add a coupling agent, and stir evenly at room temperature to obtain a carbon fiber dispersion; add lignin, carbon fiber dispersion and Lewis acid to the mixed solvent, and stir continuously at 60-75℃ for 4-6 hours to make the mixture evenly dispersed, filter, wash and dry to obtain the functional filler. S2. Dissolve phenol in tetrahydrofuran, add melamine, sodium hydroxide and functional filler to phenol-tetrahydrofuran, stir continuously at 80-90℃ for 1-3h, add the first batch of 37% formaldehyde aqueous solution, stir continuously at 80-90℃ for 1-3h and add the second batch of 37% formaldehyde aqueous solution, after the reaction is completed, distill under reduced pressure to obtain modified phenolic resin. S3. Mix modified phenolic resin, antibacterial agent, diluent, plasticizer and deionized water to obtain modified phenolic resin adhesive; The coupling agent in step S1 is composed of γ-aminopropyltrimethoxysilane and isopropyl triisostearate titanate in a mass ratio of 16-20:

1. The mixed solvent in step S1 consists of 2-p-chlorobenzylpyridine, 1-butyl-3-methylimidazolium chloride and fumaric acid in a molar ratio of 8-12:1-3:1-3. In step S2, the ingredients by weight are 14-18 parts phenol, 6-10 parts functional filler, 2-6 parts melamine, 1-3 parts sodium hydroxide, 34-38 parts 37% formaldehyde aqueous solution, and 80-100 parts tetrahydrofuran. In step S3, the components by weight are 40-44 parts modified phenolic resin, 16-20 parts diluent, 1-3 parts plasticizer, 1-3 parts antibacterial agent, and 80-100 parts deionized water. The antibacterial agent in step S3 is prepared by the following method: (1) Add citric acid and hydroquinone to a silver nitrate solution with a concentration of 0.01-0.1 M, stir evenly, heat to 60-80℃, keep warm and stir for 20-40 min to obtain a silver solution; (2) Chitosan powder is added to deionized water to prepare a chitosan solution with a mass concentration of 11-15%. Geraniol and silver solution are added sequentially while stirring. After stirring evenly, the pH is adjusted to 6.0-7.

0. After standing for 3-5 hours, the solution is filtered and dried to obtain the antibacterial agent.

2. The method for preparing the modified phenolic resin adhesive according to claim 1, characterized in that, The Lewis acid in step S1 is any one of ferric chloride, aluminum chloride, or aluminum oxide.

3. The method for preparing the modified phenolic resin adhesive according to claim 1, characterized in that, The diluent in step S3 is at least one of isopropanol, ethanol, and ethylene glycol.

4. The method for preparing the modified phenolic resin adhesive according to claim 1, characterized in that, The plasticizer in step S3 is at least one of dioctyl phthalate, triphenyl phosphate, and dipentaerythritol ester.

5. A modified phenolic resin adhesive, characterized in that, It is prepared by the method of any one of claims 1-4 for the preparation of modified phenolic resin adhesive.

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