Nano-flower material for modified plywood, nano-flower material modified urea-formaldehyde resin adhesive as well as preparation method and application of nano-flower material modified urea-formaldehyde resin adhesive

Abstract

The invention discloses a nanoflower material for modified plywood, a nanoflower material modified urea-formaldehyde resin adhesive and a preparation method and application of the nanoflower material for modified plywood, the nanoflower material is used for modifying plywood and comprises the following raw materials in parts by weight: 30-60 parts of deionized water, 60-150 parts of Co (NO3) 3.6 H2O, 30-75 parts of Zn (NO3) 2.6 H2O, 150-375 parts of Co (NH2) 2 and 70-160 parts of NaH2PO4. The nano material disclosed by the invention is in a nanoflower shape, has the advantage of high specific surface area, and is high in formaldehyde adsorption capacity; the nanoflower material is simple in component, convenient to synthesize and relatively low in production cost; according to the preparation method of the nanoflower material modified urea-formaldehyde resin adhesive and the application of the nanoflower material modified urea-formaldehyde resin adhesive to plywood, the preparation method is simple in step, reaction conditions are easy to realize, an existing urea-formaldehyde resin synthesis process does not need to be changed, a plywood production process does not need to be adjusted, and the nanoflower material modified urea-formaldehyde resin adhesive has a wide market application prospect.

Description

Technical Field

[0001] This invention belongs to the field of adhesives, and particularly relates to a modified plywood nanoflower material, a urea-formaldehyde resin adhesive modified with the nanoflower material, its preparation method, and its application. Background Technology

[0002] Urea-formaldehyde resin adhesives have advantages such as wide availability of raw materials, good water solubility, high curing strength, and low price. Plywood made with urea-formaldehyde resin adhesives is widely used in furniture manufacturing, interior decoration, vehicle and shipbuilding, and other fields. However, urea-formaldehyde resin adhesives release formaldehyde during use, polluting the environment. Long-term exposure to formaldehyde levels above 0.08 PPM can cause health problems such as respiratory and central nervous system damage. Therefore, exploring ways to reduce formaldehyde release from plywood is crucial for improving the human living environment.

[0003] Nanomaterials are materials with at least one dimension between 1 and 100 nm. Compared to traditional materials, nanomaterials possess advantages such as high porosity, high specific surface area, regular structure, and tunable pore size, giving them the ability to store gases. Therefore, nanomaterials have been used for the physical adsorption of formaldehyde molecules from the air. However, the adsorption of formaldehyde molecules by nanomaterials suffers from problems such as long adsorption time and low adsorption efficiency. Therefore, improving the formaldehyde adsorption capacity and efficiency of nanomaterials and adding them to urea-formaldehyde resin adhesives to enhance the environmental performance of urea-formaldehyde resins and control the formaldehyde release from plywood is of great significance. Summary of the Invention

[0004] The technical problem to be solved by this invention is to overcome the deficiencies and defects mentioned in the background art above, and to provide a modified plywood nanoflower material, a urea-formaldehyde resin adhesive modified with the nanoflower material, its preparation method, and its application. To solve the above technical problem, the technical solution proposed by this invention is as follows:

[0005] A nanoflower material, said nanoflower material for modifying plywood, comprises the following raw materials in parts by weight:

[0006] 30-60 parts deionized water, 60-150 parts Co(NO3)3·6H2O, 30-75 parts Zn(NO3)2·6H2O, 150-375 parts Co(NH2)2, and 70-160 parts NaH2PO4.

[0007] The overall morphology of the nanoflower material has a central core, from which many nanoscale "petals" radiate outward. These "petals" are loosely and irregularly arranged, similar to the shape of flowers in nature.

[0008] The surface of the nanoflowers is highly uneven, with obvious protrusions and depressions. The protrusions are formed by the edges of nanoscale "petals" and their interlacing and stacking, giving the nanoflowers a high degree of roughness and rich texture. The nanoflowers have a large specific surface area and a porous layered structure, which, through electrostatic interactions, helps to capture free formaldehyde in the adhesive.

[0009] Under the same technical concept, the present invention also provides a method for preparing nanoflower materials, specifically including the following steps:

[0010] (1) Dissolve Co(NO3)3·6H2O, Zn(NO3)2·6H2O, Co(NH2)2 and NaH2PO4 in deionized water and stir until homogeneous to obtain a mixed solution;

[0011] (2) After heating the mixed solution at 120-160℃ for 6-10h, cool it to room temperature and take it out, and wash it with anhydrous ethanol to obtain nanoflower material.

[0012] Preferably, the mixing process includes stirring on a magnetic stirrer for 12-18 minutes; the heating is carried out in a high-pressure reactor at a pressure of 0.2-0.5 MPa; and the washing is performed 2-3 times.

[0013] Under the same technical concept, the present invention also provides a urea-formaldehyde resin adhesive modified with nanoflower materials, wherein the urea-formaldehyde resin adhesive comprises the following raw materials in parts by weight:

[0014] The ingredients are: 20-30 parts nanoflower material, 60-90 parts formaldehyde, 80-180 parts urea, 30-40 parts sodium hydroxide solution and / or 10-20 parts formic acid solution.

[0015] Under the same technical concept, the present invention also provides a method for preparing the urea-formaldehyde resin adhesive modified with the aforementioned nanoflower material, specifically including the following steps:

[0016] (1) Heat and stir the formaldehyde solution;

[0017] (2) Add NaOH solution and / or formic acid solution to formaldehyde solution to adjust the pH of the reaction solution, add nanoflower material, and add urea in batches, keep warm, cool down, and discharge to obtain urea-formaldehyde resin adhesive modified with nanoflower material.

[0018] NaOH solution and formic acid solution are used in the preparation process of urea-formaldehyde resin adhesive to adjust the pH value.

[0019] Preferably, the amount of formaldehyde solution added in step (1) is 300-340g, and the heating and stirring container is a three-necked round-bottom flask with a reflux condenser, a thermometer and a stirrer, and heating is started at the same time as the stirrer is turned on.

[0020] Preferably, step (2) involves adding NaOH solution to adjust the pH of the reaction solution, adding nanoflower materials, adding urea in batches, maintaining the temperature, and cooling down, specifically including:

[0021] Adjust the pH of the reaction solution to 7.5–8.5 using NaOH solution. Add the first batch of urea and slowly heat to 80–90°C at a rate of 1.2–1.8°C / min. Hold at this temperature for 30–40 min. Add the nanoflower material and continue the reaction for another 30–40 min. Adjust the pH of the reaction solution to 4.8–5.4 and continue heating until the viscosity of the reaction solution reaches 50–55 mPa·s. Adjust the pH of the reaction solution to 6.8–7.5 and add the second batch of urea. Hold at this temperature until the viscosity of the reaction solution reaches 50–55 mPa·s. Adjust the pH of the reaction solution to 7.0–8.0 and cool to 60–70°C. Add the remaining urea and hold at this temperature for 20–30 min. Cool to below 40°C. The first batch of urea accounts for 40–50% of the total, the second batch accounts for 10–20%, and the third batch accounts for 30–40%.

[0022] Under the same technical concept, the present invention also provides an application of the urea-formaldehyde resin adhesive modified with the aforementioned nanoflower material, wherein the urea-formaldehyde resin adhesive modified with the nanoflower material is used to prepare plywood, specifically including the following steps:

[0023] The modified urea-formaldehyde resin adhesive made from nanoflower materials was mixed with a curing agent to obtain the prepared adhesive.

[0024] Apply 140-160g / m² of resin to both sides of the poplar wood. 2 After the prepared modified urea-formaldehyde resin adhesive is applied, it is left to stand for 5-6 minutes and then assembled. It is then hot-pressed under the following conditions: pressure 1.1-1.5 MPa, temperature 100-125℃, and time 6-12 minutes, to obtain plywood samples.

[0025] Preferably, the curing agent is ammonium chloride.

[0026] Urea-formaldehyde resin can cure at heating or room temperature, but the curing time is long, curing is incomplete, and the adhesive quality is poor. Ammonium chloride is a commonly used curing agent for urea-formaldehyde resin. When mixed with urea-formaldehyde resin, it reacts with free formaldehyde or formaldehyde released during condensation, lowering the pH value of the resin and thus accelerating curing, allowing it to reach higher adhesive strength in a shorter time. Improved performance: An appropriate amount of ammonium chloride curing agent can make the cured urea-formaldehyde resin adhesive form a denser cross-linked structure, thereby improving the adhesive strength, water resistance, and other properties. Without a curing agent, the curing speed of urea-formaldehyde resin adhesive is very slow, resulting in extremely low efficiency in practical applications and potentially failing to achieve the desired degree of curing, leading to poor adhesive quality and failure to meet usage requirements, such as insufficient adhesive strength and poor water resistance.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] (1) The nanomaterial of the present invention has a nanoflower morphology and has the advantage of high specific surface area and strong adsorption capacity for formaldehyde. The nanoflower material has simple composition, is easy to synthesize, and has relatively low production cost, which improves the problems of long adsorption time and low adsorption efficiency of nanomaterials in the prior art when adsorbing formaldehyde molecules in the air.

[0029] (2) The preparation method of the nanoflower material modified urea-formaldehyde resin adhesive of the present invention has the characteristics of simple steps and easy reaction conditions, and has broad market application prospects.

[0030] (3) The formaldehyde release of plywood prepared by the present invention using nano-flower material modified urea-formaldehyde resin adhesive is reduced. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 These are TEM images of the synthesized nanoflower materials;

[0033] Figure 2 This is a SEM image of plywood pressed with urea-formaldehyde resin adhesive modified with nano-flower materials.

[0034] Figure 3 The plywood made from the nanoflower material modified with urea-formaldehyde resin adhesive prepared in Example 1 and the formaldehyde release spectrum of the plywood in Comparative Example 1 are shown.

[0035] Figure 4The images show the internal bond strength of the plywood made from the nanoflower material modified with urea-formaldehyde resin adhesive prepared in Example 1 and the plywood in the comparative example.

[0036] Figure 5 This is the BET spectrum of the nanoflower material prepared in Example 1. Detailed Implementation

[0037] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0038] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0039] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0040] Example 1:

[0041] This embodiment provides a nanoflower material for modifying plywood, comprising the following raw materials by weight: 60g deionized water, 150g Co(NO3)3·6H2O, 75g Zn(NO3)2·6H2O, 375g Co(NH2)2, and 160g NaH2PO4.

[0042] This embodiment also provides a method for preparing nanoflower materials, including the following steps:

[0043] Weigh Co(NO3)3·6H2O, Zn(NO3)2·6H2O, Co(NH2)2 and NaH2PO4 at room temperature and dissolve them in deionized water to obtain a mixed solution. Place the mixed solution on a magnetic stirrer and stir for 15 min. Place the stirred solution into a high-pressure reactor with a pressure of 0.5 MPa and heat at 140℃ for 8 h. After cooling to room temperature, remove the sample and wash it three times with anhydrous ethanol to obtain nanoflower materials.

[0044] This embodiment also provides a method for preparing urea-formaldehyde resin modified with nanoflower materials, including the following steps:

[0045] (1) Add 90g of formaldehyde solution to a three-necked round-bottom flask equipped with a reflux condenser and a thermometer, and start heating while turning on the stirrer.

[0046] (2) Adjust the pH of the reaction solution to 7.5 with NaOH solution, add 80g of the first batch of urea, slowly heat (1.5℃ / min) to 80℃, keep warm for 30min, add 30g of nanoflower material, react for 30min, adjust the pH of the reaction solution to 4.8 with formic acid solution, continue to keep warm until the viscosity of the reaction solution is 50mPa·s, then adjust the pH of the reaction solution to 6.8. Add 29.2g of the second batch of urea, keep warm until the viscosity of the reaction solution reaches 50mPa·s, then stop the warming. Adjust the pH of the reaction solution to 7.0, cool down to 60℃, add the remaining 67.2g of urea, keep warm for 30min, cool down to below 40℃ and discharge the material to obtain the nanoflower material modified urea-formaldehyde resin adhesive; during the entire reaction process, 35g of NaOH solution and 13g of formic acid solution were used to adjust the pH of the reaction solution.

[0047] This embodiment also provides an application of nanoflower material modified urea-formaldehyde resin, including the following steps:

[0048] Take 30g of nano-flower material modified urea-formaldehyde resin adhesive and mix it with 2% NH4Cl curing agent (solid content of 2% of the added amount) to obtain the prepared adhesive.

[0049] Apply 140g / m² to both sides of the poplar wood. 2 The nano-flower material modified urea-formaldehyde resin adhesive was applied and left to stand for 5 minutes before being assembled (the wood after application was placed on the worktable of the press in three layers). Then, it was hot-pressed under pressure, temperature and time of 1.1 MPa, 100℃ and 6 minutes respectively to obtain plywood samples.

[0050] The internal bond strength and formaldehyde emission of plywood were tested. The internal bond strength test procedure refers to GB / T 17657-2022 (4.11 Determination of Internal Bond Strength), and the formaldehyde emission test procedure refers to GB / T 17657-2022 (1m 3 Climate chamber method).

[0051] Example 2:

[0052] The preparation method in this embodiment is the same as that in Example 1, the only difference being that 26.1g of nanoflower material is used.

[0053] Example 3:

[0054] The preparation method in this embodiment is the same as that in Example 1, the only difference being that 24.2g of nanoflower material is used.

[0055] Comparative Example 1:

[0056] The preparation method of this comparative example is the same as that of Example 1, except that nanoflower materials are not used.

[0057] Test results: Figure 1 The image shows the TEM image of the synthesized nanoflower material; as can be seen from the image, the synthesized multilayer nanostructure material resembles the shape of flower petals. Figure 2 The images show SEM images of the urea-formaldehyde resin adhesive-pressed plywood of the examples and comparative examples, where (a) is the SEM image of the urea-formaldehyde resin adhesive-pressed plywood of Example 1, (b) is the SEM image of the urea-formaldehyde resin adhesive-pressed plywood of Example 2, (c) is the SEM image of the urea-formaldehyde resin adhesive-pressed plywood of Example 3, and (d) is the SEM image of the urea-formaldehyde resin adhesive-pressed plywood of Comparative Example 1.

[0058] from Figure 2 (a) The nanoflower material exhibits a clustered aggregation at the bonding interface, bonded to the surrounding urea-formaldehyde resin adhesive. Some areas show a relatively smooth surface, indicating good compatibility between the nanoflower material and the adhesive, with the nanoflower material being uniformly dispersed and participating in the construction of the bonding interface structure to a certain extent. (b) The clustered structure of the nanoflower material is more pronounced, and the number of sheet-like structures in the surrounding adhesive increases, suggesting that the nanoflower material may induce the directional arrangement or reaction of certain components in the adhesive, resulting in a more complex microstructure. (c) The clustered structure of the nanoflower material is somewhat weakened, and the nanoflower material appears to be interspersed within a fibrous structure. (d) Without nanoflower modification, the bonding interface structure is relatively simple and rough, mainly consisting of blocky and irregular textures, lacking the fine structure provided by the nanoflower material. Through multiple processes including physical adsorption, chemical curing, and structural optimization, the nanoflower material effectively reduces the formaldehyde release from plywood.

[0059] Figure 3 The graphs show the formaldehyde release of plywood made from nanoflower material modified with urea-formaldehyde resin adhesive prepared in Example 1 and plywood made in Comparative Example 1. As can be seen from the graphs, Example 1 has the best formaldehyde absorption effect, and the formaldehyde release is much lower than that of the comparative example. Examples 2 and 3 are slightly higher than Example 1, but still show a great improvement.

[0060] Figure 4 The figures show the internal bond strength of the plywood made from the nanoflower material modified with urea-formaldehyde resin adhesive prepared in Example 1 and the plywood in Comparative Example 1. The data in the figures show that the internal bond strength of Examples 1-3 is not significantly different from that of the comparative example, and the mechanical properties remain stable.

[0061] Figure 5 This is the BET adsorption spectrum of the nanoflower material prepared in Example 1. It can be seen that there is a sudden increase in adsorption capacity at a relative pressure of 0.8-1.0, which reflects the large specific surface area, complex microporous structure, and strong adsorption capacity of the material.

Claims

1. A modified plywood nanoflower material, characterized in that, The following ingredients are included by weight: 30-60 parts deionized water, 60-150 parts Co(NO3)3·6H2O, 30-75 parts Zn(NO3)2·6H2O, 150-375 parts Co(NH2)2, and 70-160 parts NaH2PO4.

2. A method for preparing the nanoflower material as described in claim 1, characterized in that, Specifically, the following steps are included: (1) Dissolve Co(NO3)3·6H2O, Zn(NO3)2·6H2O, Co(NH2)2 and NaH2PO4 in deionized water and stir until homogeneous to obtain a mixed solution; (2) After heating the mixed solution at 120-160℃ for 6-10h, cool it to room temperature and take it out, and wash it with anhydrous ethanol to obtain nanoflower material.

3. The preparation method according to claim 2, characterized in that, The mixing process includes stirring on a magnetic stirrer for 12-18 minutes; the heating is carried out in a high-pressure reactor at a pressure of 0.2-0.5 MPa; and the washing is performed 2-3 times.

4. A urea-formaldehyde resin adhesive modified with nano-flower materials, characterized in that, The urea-formaldehyde resin adhesive comprises the following raw materials in parts by weight: The ingredients are: 20-30 parts nanoflower material, 60-90 parts formaldehyde solution, 80-180 parts urea, 30-40 parts sodium hydroxide solution and / or 10-20 parts formic acid solution.

5. A method for preparing a urea-formaldehyde resin adhesive modified with nanoflower materials as described in claim 4, characterized in that, Specifically, the following steps are included: (1) Heat and stir the formaldehyde solution; (2) Add NaOH solution and / or formic acid solution to formaldehyde solution to adjust the pH of the reaction solution, add nanoflower material, and add urea in batches, keep warm, cool down, and discharge to obtain urea-formaldehyde resin adhesive modified with nanoflower material.

6. The preparation method according to claim 5, characterized in that, The heating and stirring container mentioned in step (1) includes a three-necked round-bottom flask with a reflux condenser, a thermometer, and a stirrer. Heating begins simultaneously with turning on the stirrer.

7. The preparation method according to claim 6, characterized in that, Step (2) involves adding NaOH solution and / or formic acid solution to adjust the pH of the reaction solution, adding nanoflower material, adding urea in batches, maintaining the temperature, and cooling down. Specifically, this includes: Adjust the pH of the reaction solution to 7.5–8.5 using NaOH solution, add the first batch of urea, and slowly heat to 80–90°C at a rate of 1.2–1.8°C / min. Hold at this temperature for 30–40 min, then add the nanoflower material and continue the reaction for another 30–40 min. Adjust the pH of the reaction solution to 4.8–5.4 and continue heating until the viscosity of the reaction solution reaches 50–55 mPa·s. Adjust the pH of the reaction solution to 6.8–7.5, add the second batch of urea, and hold at this temperature until the viscosity of the reaction solution reaches 50–55 mPa·s. Adjust the pH of the reaction solution to 7.0–8.0, cool to 60–70°C, add the remaining urea, hold at this temperature for 20–30 min, and then cool to below 40°C.

8. The application of a urea-formaldehyde resin adhesive modified with nanoflower material as described in claim 4, or a urea-formaldehyde resin adhesive modified with nanoflower material prepared according to any one of claims 5-7, characterized in that, The preparation of plywood using the urea-formaldehyde resin adhesive modified with the nano-flower material specifically includes the following steps: The modified urea-formaldehyde resin adhesive made from nanoflower materials was mixed with a curing agent to obtain the prepared adhesive. Apply 140-160g / m² of resin to both sides of the poplar wood. 2 After the prepared modified urea-formaldehyde resin adhesive is applied, it is left to stand for 5-6 minutes and then assembled. It is then hot-pressed under the following conditions: pressure 1.1-1.5 MPa, temperature 100-125℃, and time 6-12 minutes, to obtain plywood samples.

9. The application of the urea-formaldehyde resin adhesive modified with nanoflower material as described in claim 8, characterized in that, The curing agent is ammonium chloride.

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