Resorcinol adhesive for outdoor wood and preparation method of resorcinol adhesive

Abstract

The invention relates to the field of chemical materials, and discloses a resorcinol adhesive for outdoor wood, the resorcinol adhesive comprises a main agent and a curing agent, the main agent comprises the following components: 10-15% of a formaldehyde solution; 2%-5% of water; 20% to 25% of resorcinol; 3%-6% of ethanol; 3%-7% of glycerol; 1%-3% of a sodium hydroxide solution; 0.5%-2% of p-toluenesulfonic acid; the ratio of the main agent to the curing agent is 100: (10-20). According to the adhesive, resorcinol and formaldehyde are used as main components, and resorcinol formaldehyde resin formed in the addition polycondensation reaction process has excellent cohesiveness. The resorcinol is used as a phenolic compound to improve the water resistance and high temperature resistance of the adhesive, so that the adhesive is particularly suitable for outdoor environments and can bear changes under different weather conditions without losing efficacy, and meanwhile, the added nano-scale titanium dioxide not only enhances the mechanical strength of the adhesive, but also improves the service life of the adhesive. Due to the excellent photocatalytic performance, the adhesive is helped to resist long-term ultraviolet irradiation, and aging caused by ultraviolet irradiation is prevented.

Description

Technical Field

[0001] The invention relates to the technical field of chemical materials, in particular to a resorcinol adhesive for outdoor wood and a preparation method thereof. Background Art

[0002] In outdoor wood applications, the choice of bonding materials is critical to ensuring the integrity and durability of the structure. Although the adhesives widely used in the market, such as urea-formaldehyde adhesive and phenolic adhesive, have good initial bonding strength, these traditional adhesives face several major problems, especially in applications in outdoor environments.

[0003] First, these adhesives are usually not resistant to water and environmental changes, especially when exposed to changing weather conditions for a long time, such as frequent rain and sun exposure. This makes the bonding interface susceptible to hydrolysis and aging, which in turn affects the stability and safety of the entire structure. Second, these materials are prone to degradation and embrittlement under ultraviolet radiation. Long-term ultraviolet exposure will accelerate the aging process of the material, significantly reducing the bonding performance and the service life of the material.

[0004] In addition, the preparation process of traditional adhesives often lacks effective reaction condition control, such as precise regulation of temperature, pH value and reaction time. This lack of control not only affects the performance consistency of the adhesive, but may also lead to safety risks and increased costs in the production process. For example, improper reaction conditions may trigger an overly fast reaction rate, resulting in abnormally high heat and pressure, increasing the risk of production accidents.

[0005] Therefore, the existing technology urgently needs to be improved to develop a new adhesive with higher durability, better environmental stability and more controllable preparation process to meet the stringent requirements for bonding materials in outdoor wood applications. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention provides a resorcinol adhesive for outdoor wood and a preparation method, aiming to overcome the durability problems of traditional adhesives in outdoor environments and the control difficulties of the preparation process. The adhesive is mainly composed of a resorcinol formaldehyde resin prepared by an addition polycondensation reaction of resorcinol and formaldehyde, and exhibits excellent adhesion and excellent water resistance. By introducing nano-scale titanium dioxide and specific ultraviolet absorbers, the resistance to ultraviolet rays and the aging of materials can be effectively enhanced, which greatly improves the stability and durability of the product outdoors. In addition, the precisely controlled preparation process, such as the appropriate temperature, pH value adjustment and the use of specific additives, optimizes the quality and production efficiency of the adhesive. The added mildew inhibitor also significantly improves the mildew-proof effect of the material in a humid environment and extends the service life of the wood. Overall, the present invention provides an efficient, safe, reliable and economical solution for outdoor wood bonding.

[0007] To achieve the above objectives, the present invention is implemented by the following technical scheme: a resorcinol adhesive for outdoor wood, comprising a main agent and a curing agent, wherein the main agent comprises the following components: Formaldehyde solution: 10%-15%; Water: 2%-5%; Resorcinol: 20%-25%; Ethanol: 3%-6%; Glycerin: 3%-7%; Sodium hydroxide solution: 1%-3%; p-Toluenesulfonic acid: 0.5%-2%; The ratio of the main agent to the curing agent is 100: (10-20); The mass percentages of the components are based on the total amount of the adhesive.

[0008] Preferably, the resorcinol adhesive further comprises at least one additive selected from the following combination: 0.1%-1% of nano-sized titanium dioxide, 0.1%-0.5% of ultraviolet absorber and 0.2%-1% of mildewproofing agent.

[0009] Preferably, the nano-scale titanium dioxide is selected from titanium dioxide powder with a nano-particle size range of 20-50 nanometers, the ultraviolet absorber is selected from 2-hydroxybenzoic acid benzyl ester or 4-methoxybenzoic acid methyl ester, and the mildew inhibitor is selected from benzimidazole compounds such as clarithromycin or ammonium bicarbonate.

[0010] Preferably, the ethanol is used to adjust the viscosity of the reaction medium and to assist the mixing of catechol and formaldehyde as a solvent.

[0011] Preferably, a method for preparing a resorcinol adhesive for outdoor wood, the resorcinol adhesive comprises two parts: a main agent and a curing agent, wherein: The preparation method of the main agent is as follows: S1. In a reaction kettle equipped with stirring and heating equipment, water, glycerol, ethanol, and resorcinol are added in sequence, and heated to 75°C to ensure that the resorcinol is completely dissolved; S2. While maintaining the temperature in the range of 75°C to 80°C, gradually dropwise adding formaldehyde solution and sodium hydroxide solution for 1.5-2 hours; S3, after completing step S2, continue the reaction for 1 hour, during which p-toluenesulfonic acid is dissolved in ethanol and put into the reactor, and the pH value is adjusted to 6.5-7, and finally the temperature is lowered and the material is discharged; The preparation method of the curing agent is specifically as follows: Step 1: Use suitable grinding equipment, such as a ball mill or a hammer mill, to crush the bulk paraformaldehyde raw material into a particle size of 150-200 mesh to increase its surface area and improve the reaction efficiency with the main agent; Step 2: Screen the coconut shell raw materials through a vibrating screen device to remove larger particles and impurities and obtain coconut shell powder with uniform particle size to ensure the uniformity of curing agent mixing and the consistency of the final product; Step 3: Put the screened paraformaldehyde powder and coconut shell powder into a mixer according to a mass ratio of 40:60 and mix thoroughly for at least 1 hour to ensure that the two powders are fully fused to form a uniform curing agent; Step 4: After mixing is completed, the mixed curing agent is discharged from the mixer and stored in a suitable container for future use to prevent moisture or contamination to ensure the quality and performance of the curing agent.

[0012] Preferably, the amount of ethanol used in step S1 is 3%-7% of the total reaction volume.

[0013] Preferably, the formaldehyde solution and the sodium hydroxide solution are added in step S2 by slow dripping to control the reaction rate and heat release, and to ensure sufficient mixing and uniform reaction of the reactants.

[0014] Preferably, in step S2, the aldehyde solution is 37% formaldehyde solution and the sodium hydroxide solution is 30% sodium hydroxide solution.

[0015] Preferably, a method of using a resorcinol adhesive comprises mixing a main agent and a curing agent in a ratio of 100:(10-20), uniformly coating the mixture on the surface of outdoor wood or bamboo material, and applying a pressure of 0.1-1.0 MPa until the mixture is cured.

[0016] Preferably, a resorcinol adhesive is prepared by a preparation method of a resorcinol adhesive for outdoor wood, wherein the synthesis reaction of the adhesive is an addition polycondensation reaction to form a liquid resorcinol formaldehyde resin.

[0017] The present invention provides a resorcinol adhesive for outdoor wood and a preparation method thereof. It has the following beneficial effects: 1. The adhesive uses resorcinol and formaldehyde as the main components, and the resorcinol formaldehyde resin formed in the addition polycondensation reaction has excellent adhesion. Resorcinol as a phenolic compound improves the water resistance and high temperature resistance of the adhesive, making the adhesive particularly suitable for outdoor environments and able to withstand changes in different climatic conditions without failure.

[0018] 2. The nano-sized titanium dioxide added in the present invention not only enhances the mechanical strength of the adhesive, but also helps the adhesive resist long-term ultraviolet radiation due to its excellent photocatalytic performance, thereby preventing aging caused by ultraviolet radiation. In addition, ultraviolet absorbers such as 2-hydroxybenzoic acid benzyl ester or 4-methoxybenzoic acid methyl ester further enhance the anti-ultraviolet ability, ensuring the stability and durability of the adhesive when used outdoors.

[0019] 3. In the preparation process of the present invention, the use of ethanol optimizes the viscosity and uniformity of the reaction medium, ensures the uniformity of the chemical reaction, and thus improves the consistency and quality of the final product. The method of slowly dripping formaldehyde solution and sodium hydroxide solution controls the reaction rate and heat release, reduces the possibility of side reactions, and improves the safety and yield of the reaction. The precise ratio and preparation method of the curing agent ensure the high efficiency and economy of the adhesive when used. The curing agent mixed by the mixer has excellent dispersibility and reactivity, making the application of the adhesive on outdoor wood more efficient and convenient.

[0020] 4. The mildew inhibitor added in the present invention, such as benzimidazole compounds (clathromycin or ammonium bicarbonate), effectively prevents the growth of mold in adhesives and bonding materials in a humid environment, which is particularly important for materials susceptible to mold such as outdoor wood, thereby extending the service life of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The reaction equation diagram of the adhesive of the present invention is DETAILED DESCRIPTION

[0022] The following will be combined with the drawings in the specification of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example

[0023] Please see attached Figure 1 : Example 1: Highly weather-resistant outdoor furniture bonding formula: Formaldehyde solution: 15% Water: 5% Resorcinol: 25% Ethanol: 6% Glycerin: 7% Sodium hydroxide solution: 3% p-Toluenesulfonic acid: 2% Nano-sized titanium dioxide: 1% UV absorber (benzyl 2-hydroxybenzoate): 0.5% Antifungal agent (Clarithromycin): 1% Preparation steps: The main agent is prepared according to steps S1 to S3 of claim 5.

[0024] The preparation of the curing agent follows steps 1 to 4 of claim 5.

[0025] Mix the main agent and curing agent in a ratio of 100:20 for bonding outdoor wooden furniture.

[0026] In summary: The adhesive provided in this embodiment is suitable for outdoor furniture, and can extend the service life and appearance of furniture outdoors by enhancing ultraviolet protection and mildew resistance.

[0027] Example 2: Outdoor wood bonding in low temperature environment formula: Formaldehyde solution: 10% Water: 2% Resorcinol: 20% Ethanol: 3% Glycerin: 3% Sodium hydroxide solution: 1% p-Toluenesulfonic acid: 0.5% Nano-sized titanium dioxide: 0.1% UV absorber (methyl 4-methoxybenzoate): 0.1% Antifungal agent (ammonium bicarbonate): 0.2% Preparation steps: The preparation of the main agent is described in claim 5.

[0028] The curing agent is prepared according to steps one to four.

[0029] The base agent and curing agent are mixed in a ratio of 100:10 and used in a low temperature (-10°C to 0°C) environment.

[0030] Summary: This embodiment is specially designed for low temperature environment, and the adhesive formula ensures excellent adhesion under severe cold conditions.

[0031] Example 3: Wood bonding in high humidity environment formula: Formaldehyde solution: 12% Water: 4% Resorcinol: 22% Ethanol: 4% Glycerin: 5% Sodium hydroxide solution: 2% p-Toluenesulfonic acid: 1% Nano-sized titanium dioxide: 0.5% UV absorber: 0.3% Antifungal agent: 0.5% Preparation steps: The main agent and curing agent were prepared according to the above-mentioned preparation method.

[0032] Mix the main agent and curing agent in a ratio of 100:15, suitable for high humidity environments such as tropical and subtropical areas.

[0033] Summary: Suitable for high humidity environments, especially enhanced mildew resistance, suitable for tropical and subtropical outdoor wood use.

[0034] Example 4: Rapid Curing Outdoor Wood Repair formula: Formaldehyde solution: 14% Water: 3% Resorcinol: 24% Ethanol: 5% Glycerin: 6% Sodium hydroxide solution: 2% p-Toluenesulfonic acid: 1.5% Nano-sized titanium dioxide: 0.8% UV absorber: 0.4% Antifungal agent: 0.8% Preparation steps: The preparation process of the main agent and the curing agent according to claim 5 is followed.

[0035] Mix ratio 100:18 for outdoor wood where quick touch-ups are required.

[0036] Summary: This formula provides fast curing properties suitable for emergency repairs, reducing repair time and quickly restoring the integrity of the wood structure.

[0037] Example 5: Decorative Outdoor Wood Bonding formula: Formaldehyde solution: 13% Water: 3.5% Resorcinol: 23% Ethanol: 4.5% Glycerin: 4% Sodium hydroxide solution: 1.5% p-Toluenesulfonic acid: 1% Nano-sized titanium dioxide: 0.3% UV absorber: 0.2% Antifungal agent: 0.3% Preparation steps: Prepare the main agent and curing agent according to the established method.

[0038] Use ratio 100:12, suitable for decorative outdoor wood bonding, ensuring appearance and durability.

[0039] Summary: Particularly suitable for bonding decorative wood, ensuring the bonding is beautiful and durable.

[0040] Summary: These five examples demonstrate the diverse applications of the resorcinol adhesive of the present invention, from high weather resistance to rapid repair, and each example is optimized for a specific use environment and demand. By adjusting the formula and mixing ratio, it can meet the needs of different environmental conditions and specific functions, reflecting the flexibility and efficiency of the present invention.

[0041] The adhesive synthesis reaction is an addition polycondensation reaction to form a liquid resorcinol formaldehyde resin, and its reaction equation is as follows: Figure 1 .

[0042] Comparative experiment: Comparative experiment 1: Adhesion strength and water resistance test Objective: To evaluate the bond strength and water resistance of the adhesive of the present invention compared with conventional phenolic and urea-formaldehyde adhesives in outdoor wood applications.

[0043] Existing technical solutions: Phenolic adhesive: Mainly used for wood bonding, but it has poor hydrolysis and the bonding performance will drop significantly after long-term water immersion.

[0044] Urea-formaldehyde adhesive: The first choice for indoor wood bonding, but it is sensitive to water and moisture, and the bonding strength declines rapidly in a wet environment.

[0045] Experimental conditions: Test wood: Treated pine boards Environmental simulation: continuous water immersion test for 30 days, measuring the strength of the bonding interface every 7 days Experimental data table: Adhesive type Measurement time point Adhesive of the present invention (MPa) Phenolic adhesive (MPa) Urea-formaldehyde adhesive (MPa) Initial tensile strength Day0 14 9 10 Tensile strength after 7 days Day7 13.5 8 7 Tensile strength after 14 days Day14 13 6.5 4.5 Tensile strength after 21 days Day21 12.5 5 3 Tensile strength after 30 days Day30 12 3.5 1.5 Comparative summary: The adhesive of the present invention exhibits significantly higher and more stable bonding strength, especially maintaining a relatively high bonding strength after continuous water immersion, and is suitable for long-term outdoor wood use. It has significant advantages over traditional phenolic adhesives and urea-formaldehyde adhesives.

[0046] Comparative experiment 2: UV resistance and anti-aging performance test Purpose: To compare the performance changes of the adhesive of the present invention and the prior art after long-term exposure to ultraviolet light.

[0047] Existing technical solutions: Phenolic adhesive: Darkens in color and loses strength after UV exposure.

[0048] Urea-formaldehyde adhesive: Degrades rapidly under ultraviolet light, and color and bonding properties quickly fade.

[0049] Experimental conditions: UV exposure test: Continuous exposure to simulated sunlight, test period 180 days.

[0050] Test parameters: color difference (ΔE) and bonding strength decay rate.

[0051] Experimental data table: Adhesive type Adhesive of the present invention Phenolic adhesive Urea-formaldehyde adhesive Color difference (∆E) 1.5 5 8 Strength attenuation (%) 0.1 0.45 0.65 Comparative summary: The adhesive of the present invention has significant UV resistance and anti-aging ability, and the color difference and strength attenuation after ultraviolet exposure are significantly lower than those of phenolic and urea-formaldehyde adhesives. This shows that the adhesive of the present invention is very suitable for long-term exposure to outdoor environments and provides more lasting protection.

[0052] Comparative experiment 3: mildew resistance test Objective: To compare the antifungal properties of the adhesive of the present invention and traditional adhesives in a high humidity environment.

[0053] Existing technical solutions: Phenolic Adhesive: Moderately resistant to mildew in moist environments.

[0054] Urea-formaldehyde adhesive: prone to mold and mildew growth in high humidity environments.

[0055] Experimental conditions: Environmental simulation: continuous humidity 85%RH, test period 180 days.

[0056] Evaluation criteria: mold coverage and degree of material deterioration.

[0057] Experimental data table: Adhesive type Adhesive of the present invention Phenolic adhesive Urea-formaldehyde adhesive Mold coverage (%) 0.05 0.3 0.6 Comparative Summary: The adhesive of the present invention exhibits excellent mildew resistance, with mold coverage much lower than that of traditional phenolic and urea-formaldehyde adhesives, making it an ideal choice for use in humid environments, especially in outdoor wood applications where long-term mildew protection is required.

[0058] Summary Through improved experimental design and more detailed data, the adhesive of the present invention has shown significant advantages in various performance tests, especially in water resistance, UV resistance and mildew resistance. These characteristics make the adhesive of the present invention an ideal choice for outdoor wood bonding and protection, which can significantly improve the maintenance cycle of wood and reduce maintenance costs. Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A resorcinol adhesive for outdoor wood, characterized in that: It includes a main agent and a curing agent, and the main agent includes the following components: Formaldehyde solution: 10%-15%; Water: 2%-5%; Resorcinol: 20%-25%; Ethanol: 3%-6%; Glycerin: 3%-7%; Sodium hydroxide solution: 1%-3%; p-Toluenesulfonic acid: 0.5%-2%; The ratio of the main agent to the curing agent is 100: (10-20); The mass percentages of the components are based on the total amount of the adhesive.

2. The resorcinol adhesive for outdoor wood according to claim 1, characterized in that: The resorcinol adhesive further comprises at least one additive selected from the following combinations: 0.1%-1% of nano-sized titanium dioxide, 0.1%-0.5% of ultraviolet absorber, and 0.2%-1% of mildew preventer.

3. The resorcinol adhesive for outdoor wood according to claim 2, characterized in that: The nano-scale titanium dioxide is selected from titanium dioxide powder with a nano-particle size range of 20-50 nanometers, the ultraviolet absorber is selected from 2-hydroxybenzoic acid benzyl ester or 4-methoxybenzoic acid methyl ester, and the mildew inhibitor is selected from benzimidazole compounds such as clarithromycin or ammonium bicarbonate.

4. The resorcinol adhesive for outdoor wood according to claim 1, characterized in that: The ethanol is used to adjust the viscosity of the reaction medium and as a solvent to assist in mixing the resorcinol and formaldehyde.

5. The method for preparing a resorcinol adhesive for outdoor wood according to any one of claims 1 to 4, characterized in that: The resorcinol adhesive comprises a main agent and a curing agent, wherein: The preparation method of the main agent is as follows: S1. In a reaction kettle equipped with stirring and heating equipment, water, glycerol, ethanol, and resorcinol are added in sequence, and heated to 75°C to ensure that the resorcinol is completely dissolved; S2. While maintaining the temperature in the range of 75°C to 80°C, gradually dropwise adding formaldehyde solution and sodium hydroxide solution for 1.5-2 hours; S3, after completing step S2, continue the reaction for 1 hour, during which p-toluenesulfonic acid is dissolved in ethanol and put into the reactor, and the pH value is adjusted to 6.5-7, and finally the temperature is lowered and the material is discharged; The preparation method of the curing agent is specifically as follows: Step 1: Use suitable grinding equipment, such as a ball mill or a hammer mill, to crush the bulk paraformaldehyde raw material into a particle size of 150-200 mesh to increase its surface area and improve the reaction efficiency with the main agent; Step 2: Screening the coconut shell raw material through a vibrating screen device to remove larger particles and impurities to obtain coconut shell powder with uniform particle size; Step 3: Put the screened paraformaldehyde powder and coconut shell powder into a mixer according to a mass ratio of 40:60 and mix thoroughly for at least 1 hour to ensure that the two powders are fully fused to form a uniform curing agent; Step 4: After the mixing is completed, the mixed curing agent is discharged from the mixer and stored in a suitable container for later use.

6. The method for preparing a resorcinol adhesive for outdoor wood according to claim 5, characterized in that: The amount of ethanol used in step S1 is 3%-7% of the total reaction volume.

7. The method for preparing a resorcinol adhesive for outdoor wood according to claim 5, characterized in that: In step S2, the formaldehyde solution and the sodium hydroxide solution are added in a slow dripping manner to control the reaction rate and heat release, and to ensure sufficient mixing and uniform reaction of the reactants.

8. The method for preparing a resorcinol adhesive for outdoor wood according to claim 5, characterized in that: In step S2, the aldehyde solution is 37% formaldehyde solution, and the sodium hydroxide solution is 30% sodium hydroxide solution.

9. A method for using the resorcinol adhesive according to any one of claims 1 to 8, characterized in that: The method comprises mixing a main agent and a curing agent in a ratio of 100:(10-20), applying the mixture evenly on the surface of outdoor wood or bamboo material, and applying a pressure of 0.1-1.0MPa until the mixture is cured.

10. A resorcinol adhesive prepared by the method for preparing a resorcinol adhesive for outdoor wood according to any one of claims 1 to 9, characterized in that: The synthetic reaction of the adhesive is an addition polycondensation reaction to form a liquid resorcinol formaldehyde resin.

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