Method for preparing high-strength super-tough multi-component copolymer adhesive based on confined reactor and application thereof

Abstract

The application belongs to the technical field of multivariate copolymerization adhesive, and discloses a method for preparing high-strength super-tough multivariate copolymerization adhesive based on a limited reactor and application thereof. The limited reactor is prepared by using tannic acid modified halloysite nanotubes, and covalent bonds are formed between the hydroxyl groups and the amino groups of the super-branched polyurea modified phenolic resin, so that the limited reactor is tightly connected with the surrounding phenolic resin molecular chain to form a solid three-dimensional network structure. The high length-diameter of the halloysite nanotubes promotes molecular polymerization, and the super-branched polyurea and the phenolic resin are copolymerized to enhance the toughening effect and improve the thermal stability. In addition, the multivariate copolymerization adhesive with a tough chain is added to increase the spacing between the rigid chain segments of the phenolic resin, thereby improving the toughness of the phenolic resin.

Description

Technical Field

[0001] This invention belongs to the field of multi-component copolymer adhesive technology, specifically relating to a method for preparing high-strength and ultra-tough multi-component copolymer adhesives based on a confined reactor and its application. Background Technology

[0002] As the production of engineered wood products increases, the use of traditional wood adhesives also gradually increases. However, traditional wood adhesives have curing shrinkage, and the adhesive layer is brittle after curing, resulting in poor impact resistance and easy cracking and deformation of engineered wood products.

[0003] Halloysite nanotubes possess one-dimensional hollow channels with a high aspect ratio. These channels can inhibit curing shrinkage of adhesive layers, reduce stress concentration, suppress crack propagation, and promote the formation of crazes, thereby enhancing and toughening the adhesive. As hollow confined reactors, they allow small molecules to react rapidly within the channels, promoting reaction progress and improving molecular utilization efficiency.

[0004] However, existing inorganic confined reactors have poor stability in the adhesive matrix, poor interfacial compatibility, and limited performance improvement effect on bonded wood, making it difficult to meet the performance requirements of wood adhesives.

[0005] Therefore, there is an urgent need to develop a new confined reactor to improve the strength and toughness of adhesives, thereby increasing the strength of bonded wood and overcoming the shortcomings of traditional wood adhesives, such as easy cracking and deformation of bonded wood and insufficient bonding stability. Summary of the Invention

[0006] The purpose of this invention is to provide a method and application for preparing high-strength, ultra-tough, multi-component copolymer adhesives based on a confined reactor. The preparation method described in this invention significantly improves the strength and toughness of the adhesive layer and its adhesion to the wood interface, while also significantly enhancing the adhesive's thermal stability and compressive strength.

[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for preparing a confined reactor, comprising the following steps: S1. Halloysite nanotubes dried under vacuum at 120℃, KH550 and toluene were mixed, and the mixture was dispersed by ultrasonication and filtered to obtain modified halloysite nanotubes. After washing, the modified halloysite nanotubes were obtained by vacuum drying at 60℃ for 6 h. S2. KH550 modified halloysite nanotubes were dispersed in water, tannic acid was added, the pH of the solution was adjusted to 7.5, and the reaction was stirred at 60°C for 3 hours. After vacuum drying at 60°C, a confined reactor was obtained.

[0008] Preferably, based on the mass of halloysite nanotubes added, the amount of KH550 added in step S1 is 2 mL / g, and the amount of toluene added is 20 mL / g; the ultrasonic dispersion reaction process is as follows: after ultrasonication for 30 minutes, the reaction is stirred at 130°C for 24 hours.

[0009] Preferably, the amount of tannic acid added in step S2 is 1.5 times the mass of the KH550 modified halloysite nanotubes.

[0010] The present invention also provides a multi-component copolymer adhesive, which is prepared using the above-mentioned confined reactor; The specific preparation method is as follows: Add 30-40% sodium hydroxide aqueous solution to 100g phenol to adjust the pH to 9-10, heat to 45-50℃, add 150g formaldehyde (37% by mass) and the above confined reactor, heat to 90-95℃, react for 40-50 min, cool to 70℃, add 44g formaldehyde and hyperbranched polyurea, heat to 92±2℃ and react until the viscosity is between 18-20 seconds in a Forte 4 cup. After the reaction is completed, a modified phenolic resin adhesive is obtained; then add industrial flour and mix and stir to obtain a multi-component copolymer adhesive. The hyperbranched polyurea is prepared from urea and polyethyleneimine.

[0011] Preferably, the molar ratio of formaldehyde to phenol is 2.25:1.

[0012] Preferably, the amount of phenol added to the confined reactor is 1-4% of the mass of phenol, and the amount of hyperbranched polyurea added is 5.53% of the mass of phenol, by mass percentage.

[0013] Preferably, the hyperbranched polyurea is prepared by mixing polyethyleneimine and urea in a mass ratio of 3:1 and reacting them at 130°C for 12 h.

[0014] Preferably, the amount of industrial flour added is 25% of the modified phenolic resin adhesive.

[0015] This invention also provides the application of the above-mentioned multi-component copolymer adhesive in the preparation of engineered wood panels or bamboo laminated timber.

[0016] The beneficial effects of this invention are: This invention introduces hyperbranched polyurea, giving the surface of phenolic resin a large number of amino groups. These amino groups interact with the hydroxyl groups on the surface of wood and bamboo through hydrogen bonding. Hyperbranched polyurea also crosslinks the hydroxyl groups on the cellulose in wood, enhancing the reactivity of the phenolic resin. Simultaneously, the presence of amino groups enables rapid curing of the phenolic resin. Furthermore, hyperbranched polyurea and tannic acid possess certain antibacterial properties, improving the mildew resistance of engineered wood products. The unique one-dimensional tubular structure of halloysite nanotubes allows phenol and formaldehyde to react efficiently within the channels, improving the utilization efficiency of phenol and formaldehyde molecules. The high mechanical strength of halloysite not only effectively withstands the stress transmitted by the polymer matrix but also effectively fills the pores of the phenolic resin, inhibiting the shrinkage of the cured adhesive layer to a certain extent. Tannic acid-modified halloysite nanotubes improve the dispersibility and organic-inorganic interface characteristics when blended with hyperbranched polyurea-modified phenolic resin. During synthesis, a phenolamine chemical reaction occurs between hyperbranched polyurea and tannic acid, resulting in a tight bond between the phenolic resin molecular chains and the halloysite nanotubes. Hyperbranched polymer molecules on halloysite nanotubes can efficiently conduct and dissipate stress at the halloysite nanotube / phenolic resin interface through their internal "cavity" structure and molecular chain deformation, thus avoiding stress concentration and improving toughening effect. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 The graph shows the boiling water shear strength test results of the adhesive samples in Examples 1-4 and the comparative example. Figure 2 The graph shows the results of the three-point bending strength test of the plywood made with the adhesive of Examples 1-4 and the comparative example samples. Figure 3 The graph shows the flexural modulus test results of plywood made from the adhesives used in Examples 1-4 and the comparative example samples. Detailed Implementation

[0019] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the accompanying drawings and embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0020] Unless otherwise specified, the production processes, experimental methods, or testing methods involved in the embodiments of this invention are all conventional methods in the prior art, and their names and / or abbreviations are all conventional names in the field, which are very clear and distinct in the relevant application areas. Those skilled in the art can understand the conventional process steps based on the names and apply the corresponding equipment, and implement them according to conventional conditions or the conditions recommended by the manufacturer.

[0021] The various instruments, equipment, raw materials or reagents used in the embodiments of this invention are not subject to any special restrictions on their source. They are all conventional products that can be purchased through regular commercial channels and can be prepared according to conventional methods known to those skilled in the art.

[0022] Example 1 (1) Preparation of KH550 modified halloysite nanotubes: Halloysite nanotubes were dried in a vacuum oven at 120 °C. Halloysite nanotubes (5.0 g), KH550 (10.0 mL), and toluene (100.0 mL) were placed in a round-bottom flask. The mixture was then ultrasonically dispersed for 30 minutes and stirred at 130 °C for 24 hours. The modified halloysite nanotubes were filtered and washed three times with anhydrous ethanol. Finally, the KH550 modified halloysite nanotubes were obtained by drying in a vacuum at 60 °C for 6 hours.

[0023] (2) Disperse 5 g of KH550 modified halloysite nanotubes in water to make a mass fraction of 10%, add 7.5 g of tannic acid, adjust the pH of the solution to 7.5 with 20% sodium hydroxide aqueous solution, stir the reaction at 60°C for 3 hours, and dry in a vacuum drying oven at 60°C to obtain a confined reactor.

[0024] (3) Add 2 g of urea and 6 g of polyethyleneimine to the assembled four-necked flask, and then stir the reaction at 135°C for 12 hours to obtain hyperbranched polyurea for later use.

[0025] (4) Add 100 g of phenol and 30-40% sodium hydroxide aqueous solution to the assembled four-necked flask, adjust the pH to 9-10, stir evenly, heat to 45-50℃, then slowly add 150 g of formaldehyde (37% by mass) and 1 g of confined reactor, heat to 90-95℃ and react for 40-50 min, cool to 70℃, slowly add 44 g of formaldehyde and 5.53 g of hyperbranched polyurea to the four-necked flask, heat to 92±2℃ and react until the viscosity is between 18-20 seconds of Fort-4 cup. After the reaction is completed, the modified phenolic resin adhesive is obtained.

[0026] (5) Add industrial flour to the modified phenolic resin adhesive, mix and stir to obtain a multi-component copolymer adhesive.

[0027] Example 2 (1) Preparation of KH550 modified halloysite nanotubes: Halloysite nanotubes were dried in a vacuum oven at 120 °C. Halloysite nanotubes (5.0 g), KH550 (10.0 mL), and toluene (100.0 mL) were placed in a round-bottom flask. The mixture was then ultrasonically dispersed for 30 minutes and stirred at 130 °C for 24 hours. The modified halloysite nanotubes were filtered and washed three times with anhydrous ethanol. Finally, the KH550 modified halloysite nanotubes were obtained by drying in a vacuum at 60 °C for 6 hours.

[0028] (2) Disperse 5 g of KH550 modified halloysite nanotubes in water to make a mass fraction of 10%, add 7.5 g of tannic acid, adjust the pH of the solution to 7.5 with 20% sodium hydroxide aqueous solution, stir the reaction at 60°C for 3 hours, and dry in a vacuum drying oven at 60°C to obtain a confined reactor.

[0029] (3) Add 2 g of urea and 6 g of polyethyleneimine to the assembled four-necked flask, and then stir the reaction at 135°C for 12 hours to obtain hyperbranched polyurea for later use.

[0030] (4) Add 100 g of phenol and 30-40% sodium hydroxide aqueous solution to the assembled four-necked flask, adjust the pH to 9-10, stir evenly, heat to 45-50℃, then slowly add 150 g of formaldehyde (37% by mass) and 2 g of confined reactor, heat to 90-95℃ and react for 40-50 min, cool to 70℃, slowly add 44 g of formaldehyde and 5.53 g of hyperbranched polyurea to the four-necked flask, heat to 92±2℃ and react until the viscosity is between 18-20 seconds of Fort-4 cup. After the reaction is completed, the modified phenolic resin adhesive is obtained.

[0031] (5) Add industrial flour to the modified phenolic resin adhesive, mix and stir to obtain a multi-component copolymer adhesive.

[0032] Example 3 (1) Preparation of KH550 modified halloysite nanotubes: Halloysite nanotubes were dried in a vacuum oven at 120 °C. Halloysite nanotubes (5.0 g), KH550 (10.0 mL), and toluene (100.0 mL) were placed in a round-bottom flask. The mixture was then ultrasonically dispersed for 30 minutes and stirred at 130 °C for 24 hours. The modified halloysite nanotubes were filtered and washed three times with anhydrous ethanol. Finally, the KH550 modified halloysite nanotubes were obtained by drying in a vacuum at 60 °C for 6 hours.

[0033] (2) Then, 5 g of KH550 modified halloysite nanotubes were dispersed in water to make a mass fraction of 10%, 7.5 g of tannic acid was added, the pH of the solution was adjusted to 7.5 with 20% sodium hydroxide aqueous solution, and then the reaction was stirred at 60°C for 3 hours. The reaction was then dried in a vacuum drying oven at 60°C to obtain a confined reactor.

[0034] (3) First, add 2 g of urea and 6 g of polyethyleneimine to the assembled four-necked flask, and then stir the reaction at 135°C for 12 hours to obtain hyperbranched polyurea for later use.

[0035] (4) Add 100 g of phenol and 30-40% sodium hydroxide aqueous solution to the assembled four-necked flask, adjust the pH to 9-10, stir evenly, heat to 45-50℃, then slowly add 150 g of formaldehyde (37% by mass) and 3 g of confined reactor, heat to 90-95℃ and react for 40-50 min, cool to 70℃, slowly add 44 g of formaldehyde and 5.53 g of hyperbranched polyurea to the four-necked flask, heat to 92±2℃ and react until the viscosity is between 18-20 seconds of Fort-4 cup. After the reaction is completed, the modified phenolic resin adhesive is obtained.

[0036] (5) Add industrial flour to the modified phenolic resin adhesive, mix and stir to obtain a multi-component copolymer adhesive.

[0037] Example 4 (1) Preparation of KH550 modified halloysite nanotubes: Halloysite nanotubes were dried in a vacuum oven at 120 °C. Halloysite nanotubes (5.0 g), KH550 (10.0 mL), and toluene (100.0 mL) were placed in a round-bottom flask. The mixture was then ultrasonically dispersed for 30 minutes and stirred at 130 °C for 24 hours. The modified halloysite nanotubes were filtered and washed three times with anhydrous ethanol. Finally, the KH550 modified halloysite nanotubes were obtained by drying in a vacuum at 60 °C for 6 hours.

[0038] (2) Disperse 5 g of KH550 modified halloysite nanotubes in water to make a mass fraction of 10%, add 7.5 g of tannic acid, adjust the pH of the solution to 7.5 with 20% sodium hydroxide aqueous solution, stir the reaction at 60°C for 3 hours, and dry in a vacuum drying oven at 60°C to obtain a confined reactor.

[0039] (3) Add 2 g of urea and 6 g of polyethyleneimine to the assembled four-necked flask, and then stir the reaction at 135°C for 12 hours to obtain hyperbranched polyurea for later use.

[0040] (4) Add 100 g of phenol and 30-40% sodium hydroxide aqueous solution to the assembled four-necked flask, adjust the pH to 9-10, stir evenly, heat to 45-50℃, then slowly add 150 g of formaldehyde (37% by mass) and 4 g of confined reactor, heat to 90-95℃ and react for 40-50 min, cool to 70℃, slowly add 44 g of formaldehyde and 5.53 g of hyperbranched polyurea to the four-necked flask, heat to 92±2℃ and react until the viscosity is between 18-20 seconds of Fort-4 cup. After the reaction is completed, the modified phenolic resin adhesive is obtained.

[0041] (5) Add industrial flour to the modified phenolic resin adhesive, mix and stir to obtain a multi-component copolymer adhesive.

[0042] Comparative Example Add 100 g of phenol and a 30-40% sodium hydroxide aqueous solution to the assembled four-necked flask, adjust the pH to 9-10, stir well, heat to 45-50℃, then slowly add 150 g of formaldehyde (37% by mass), heat to 90-95℃ and react for 40-50 min, cool to 70℃, slowly add 44 g of formaldehyde to the four-necked flask, heat to 92±2℃ and react until the viscosity is between 18-20 seconds in a Forte 4 cup. After the reaction is complete, phenolic resin adhesive is obtained.

[0043] Phenolic resin adhesive can be obtained by adding industrial flour to modified phenolic resin and mixing it.

[0044] The performance of the multi-component copolymer adhesives prepared in Examples 1-4 of the present invention and the phenolic resins prepared in the comparative examples were tested according to the following methods. The performance quality indicators of the resulting adhesives are shown in Tables 1 and 2.

[0045] Poplar plywood, sawn according to GB / T9846.7-2004, with sample dimensions of 100 mm × 25 mm. The glued area is 25 mm × 25 mm. Plywood preparation process parameters: glue application rate 180-200 g / m². 2 (Single-sided) Then, a flat vulcanizing agent is added, and hot-pressed at 130℃ for 300 s under a unit pressure of 1.0-1.2 MPa for 60 s. The bonding strength is determined by immersing the poplar plywood in slightly boiling water for 4 h after cooling it to room temperature, then drying it in a forced-air drying oven at (60±3)℃ for 16-20 h, immersing it in slightly boiling water for another 4 h, and then immersing it in cold water below 30℃ for at least 1 h.

[0046] For Examples 1-4 and the Comparative Example, 10 samples were taken from each group, and the average value was taken. The boiling water shear strength, three-point bending strength, and flexural modulus were tested.

[0047] Adhesive toughness evaluation test: Adhesive strips, pressed according to GBT+2567-2021, sample size: 60 mm × 15 mm × 3 mm.

[0048] Bending strength test process parameters: span L is 48 mm, test speed is 2 mm / min.

[0049] Table 1 Bond strength of the samples

[0050] Table 2. Flexural strength and flexural modulus of multi-component copolymer adhesive strips

[0051] The test results of boiling water shear strength, three-point bending strength and flexural modulus are as follows: Figure 1-3 As shown in Tables 1-2, the plywood manufactured with the multi-component copolymer adhesive in the examples exhibited a bond strength of over 0.7 MPa. The cured adhesive layer formed a uniform and dense structure, indicating that the toughness of the modified adhesive was improved.

[0052] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing a confined reactor, characterized in that, Includes the following steps: S1. Halloysite nanotubes dried under vacuum at 120℃, KH550 and toluene were mixed, and the mixture was dispersed by ultrasonication and filtered to obtain modified halloysite nanotubes. After washing, the modified halloysite nanotubes were obtained by vacuum drying at 60℃ for 6 h. S2. KH550 modified halloysite nanotubes were dispersed in water, tannic acid was added, the pH of the solution was adjusted to 7.5, and the reaction was stirred at 60°C for 3 hours. After vacuum drying at 60°C, a confined reactor was obtained.

2. The preparation method according to claim 1, characterized in that, Based on the mass of halloysite nanotubes added, the amount of KH550 added in step S1 was 2 mL / g, and the amount of toluene added was 20 mL / g; the ultrasonic dispersion reaction process was as follows: after ultrasonication for 30 minutes, the reaction was stirred at 130°C for 24 hours.

3. The preparation method according to claim 1, characterized in that, The amount of tannic acid added in step S2 is 1.5 times the mass of the KH550 modified halloysite nanotubes.

4. A multi-component copolymer adhesive, characterized in that, The multi-component copolymer adhesive is prepared using the confined reactor described in claim 1; The specific preparation method is as follows: Add 30-40% sodium hydroxide aqueous solution to 100g phenol to adjust the pH to 9-10, heat to 45-50℃, add 150g formaldehyde (37% by mass) and the confined reactor described in claim 1, heat to 90-95℃, react for 40-50 min, cool to 70℃, add 44g formaldehyde and hyperbranched polyurea, heat to 92±2℃ and react until the viscosity is between 18-20 seconds (Ford-4 cup). After the reaction is complete, a modified phenolic resin adhesive is obtained; subsequently, industrial flour is added and mixed to obtain a multi-component copolymer adhesive. The hyperbranched polyurea is prepared from urea and polyethyleneimine.

5. The multi-component copolymer adhesive according to claim 4, characterized in that, The molar ratio of formaldehyde to phenol is 2.25:

1.

6. The multi-component copolymer adhesive according to claim 4, characterized in that, The amount of phenol added to the confined reactor is 1-4% of the phenol mass, and the amount of hyperbranched polyurea added is 5.53% of the phenol mass, based on mass percentage.

7. The multi-component copolymer adhesive according to claim 4, characterized in that, The hyperbranched polyurea is prepared by mixing polyethyleneimine and urea in a mass ratio of 3:1 and reacting them at 130°C for 12 hours.

8. The multi-component copolymer adhesive according to claim 4, characterized in that, The amount of industrial flour added is 25% of the modified phenolic resin adhesive.

9. The use of the multi-component copolymer adhesive according to any one of claims 4-8 in the preparation of engineered wood panels or bamboo laminated timber.

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