A composite amide particle, a preparation method and application thereof

Abstract

This invention relates to the field of amino resin technology, and discloses a composite amide particle, its preparation method, and its application. The composite amide particle provided by this invention has a diameter of 1 mm to 5 mm and a bulk density typically of 0.65 g / cm³. 3 -1.4g / cm 3 The compressive strength is 2N-6N, and the Hall flow rate is 15.4g / s-20.8g / s. The composite amide particles of this invention have good uniformity and larger particle size, which increases the bulk density. When preparing MUF or UMF amino resins, the reaction rate of the two forms of amino groups (urea and melamine) with formaldehyde is more uniform, resulting in better resin stability. This significantly improves production efficiency, reduces transportation costs, enhances the convenience of amino resin production, reduces dust pollution at the amino resin production site, and protects the occupational health and hygiene level of the amino resin production industry.

Description

Technical Field

[0001] This invention relates to the field of amino resin technology, specifically to a composite amide particle, its preparation method, and its application. Background Technology

[0002] Amino resins are often produced by reacting melamine and amides (urea) with formaldehyde to obtain melamine-urea-formaldehyde resin (MUF) or urea-melamine-formaldehyde resin (UMF), which are widely used in wood adhesives, impregnated paper, amino coatings and other fields.

[0003] Melamine production processes are divided into gas-phase and high-pressure liquid-phase processes. In the gas-phase process, melamine is directly contacted in a circulating cold gas composed of ammonia and carbon dioxide at a temperature above 330°C, and rapidly sublimates and crystallizes, usually into an amorphous powder with a particle size of 1μm-30μm. In the high-pressure liquid-phase process, melamine crystallizes out in an ammonia solution, also as an amorphous powder with a particle size of 6μm-40μm. Regardless of the production method, melamine is always produced as micron-sized amorphous particles.

[0004] In the production of amino resins: melamine is prone to agglomeration, has poor flowability, and is difficult to operate during feeding and pouring, easily clogging pipes and screw conveyors, leading to inaccurate automatic metering by the screw conveyor, wasting time and labor, and also causing dust, environmental pollution, and occupational health risks; furthermore, the specific gravity of urea is usually 0.7 g / cm³. 3 -0.8g / cm 3 The bulk density of melamine is typically 0.35 g / cm³. 3 -0.55g / cm 3 Melamine is lightweight and tends to float on the surface of the liquid when added, making mixing difficult and requiring a longer stirring time.

[0005] Furthermore, during the preparation of amino resins, the contact effects of urea, melamine, and formaldehyde solution differ, resulting in significant variations in reaction rates and affecting the uniformity and stability of the resin. Existing technologies, such as Chinese patent documents CN1122027C, CN1275125A, CN1313451C, CN1675186A, CN101052626A, CN104788394B, and TW526185B, primarily address these issues by modifying the melamine production process or equipment to increase melamine particle size. Despite these efforts, the D50 of melamine remains only 150 μm, indicating limited improvement. Summary of the Invention

[0006] In view of this, the present invention provides a composite amide particle to solve the problems of poor uniformity and poor stability of amino resins prepared by existing technologies.

[0007] The present invention also provides a method for preparing composite amide particles.

[0008] In a first aspect, the present invention provides a composite amide particle, wherein the composite amide particle has a diameter of 1 mm-5 mm and a bulk density of 0.65 g / cm³. 3 -1.4g / cm 3 The compressive strength is 2N-6N, and the Hall flow rate is 15.4g / s-20.8g / s.

[0009] In some optional embodiments, the raw materials for the composite amide particles include melamine, urea, and additives.

[0010] In some alternative embodiments, the mass ratio of melamine to urea is 1:0.1-9.

[0011] In some optional embodiments, the content of the adjuvant is 0.1wt%-5wt%.

[0012] In some alternative embodiments, the additive includes at least one of the following: aqueous polyvinyl alcohol, silane coupling agent, aqueous diethylene glycol, aqueous triethylene glycol, silica, and alumina.

[0013] In some alternative embodiments, the silane coupling agent includes at least one of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-aminopropyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, and vinyltrimethoxysilane.

[0014] In a second aspect, the present invention provides a method for preparing the composite amide particles described in the first aspect, comprising method one or method two, wherein:

[0015] Method 1 includes the following steps:

[0016] Melamine is mixed with urea and additives, granulated, dried, and then heated at 134℃-160℃ to obtain the final product.

[0017] Method 2 includes the following steps:

[0018] Melamine is mixed with additives and molten urea, granulated, and dried to obtain the final product.

[0019] In some alternative implementations, the heating time is 5 min to 15 min.

[0020] In some alternative embodiments, the drying temperature is 75°C-110°C.

[0021] In some alternative embodiments, the moisture content of the dried particles is ≤0.1%.

[0022] In some alternative implementations, the mixing time is 15 min to 42 min.

[0023] Thirdly, the present invention provides an amino resin, comprising the composite amide particles described in the first aspect or the composite amide particles prepared by the preparation method described in the second aspect.

[0024] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0025] 1. The composite amide particles provided by this invention have a diameter of 1mm-5mm and a bulk density typically of 0.65g / cm³. 3 -1.4g / cm 3 The compressive strength is 2N-6N, and the Hall flow rate is 15.4g / s-20.8g / s. The composite amide particles of this invention have good uniformity and larger particle size, which increases the bulk density. When preparing MUF or UMF amino resins, the reaction rate of the two forms of amino groups (urea and melamine) with formaldehyde is more uniform, resulting in better resin stability. This significantly improves production efficiency, reduces transportation costs, enhances the convenience of amino resin production, reduces dust pollution at the amino resin production site, and protects the occupational health and hygiene level of the amino resin production industry.

[0026] 2. The method for preparing composite amide particles provided by the present invention involves mixing melamine and urea, granulating, drying, and heating and cooling. During the heating process, the amino groups of melamine and urea are molecularly combined, avoiding material agglomeration and clumping, resulting in good uniformity and flowability. After cooling, the strength of the composite amide particles is further improved, with a particle strength of over 2N, ensuring that the particles are not damaged during long-distance transportation. Attached Figure Description

[0027] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific 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 from these drawings without creative effort.

[0028] Figure 1 This is a flowchart of the preparation method of the composite amide particles prepared in Examples 1-4 of the present invention;

[0029] Figure 2 This is a flowchart of the preparation method of the composite amide particles prepared in Example 5 of the present invention;

[0030] Figure 3 This is a photograph of the composite amide particles prepared in Example 1 of the present invention;

[0031] Figure 4 This is a photograph of the composite amide particles prepared in Example 2 of the present invention;

[0032] Figure 5 This is a photograph of the composite amide particles prepared in Example 3 of the present invention.

[0033] Figure 6 This is a photograph of the composite amide particles prepared in Example 4 of the present invention.

[0034] Figure 7 This is a physical image of the composite amide particles prepared in Example 5 of the present invention. Detailed Implementation

[0035] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0036] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0037] To address the problems existing in the aforementioned related technologies, according to a first aspect of the present invention, the present invention provides composite amide particles with a diameter of 1 mm-5 mm and a bulk density typically of 0.65 g / cm³. 3 -1.4g / cm 3 The compressive strength is 2N-6N, and the Hall flow rate is 15.4g / s-20.8g / s; the raw materials for the composite amide particles are melamine, urea, and additives, wherein the mass ratio of melamine to urea is 1:0.1-9, and the content of the additives is 0.1wt%-5wt%; the additives include at least one of polyvinyl alcohol aqueous solution, silane coupling agent, diethylene glycol, triethylene glycol, silica, and alumina; the silane coupling agent includes at least one of γ-(2,3-epoxypropoxy)propyltrimethoxysilane (KH560), γ-aminopropyltriethoxysilane (KH540), vinyltris(2-methoxyethoxy)silane (SI602), and vinyltrimethoxysilane (SI902).

[0038] The composite amide particles of this invention have good uniformity and larger particle size, which increases the bulk density. When preparing MUF or UMF amino resins, the reaction rate of the two forms of amino groups, urea and melamine, with formaldehyde is more uniform, resulting in better resin stability. This significantly improves production efficiency, reduces transportation costs, enhances the convenience of amino resin production, reduces dust pollution at the amino resin production site, and protects the occupational health and hygiene level of the amino resin production industry.

[0039] Additives help with shaping and improve the quality of shaped particles. Aqueous solutions of polyvinyl alcohol (PVA), diethylene glycol, and triethylene glycol help with the initial agglomeration of urea and melamine mixed powders without affecting the application of the product. The addition of silica and alumina helps to adjust the particle strength and density. When adding silica and / or alumina, silane coupling agents can make the urea and melamine mixed more evenly with silica and / or alumina.

[0040] Secondly, the present invention provides a method for preparing composite amide particles, comprising the following steps:

[0041] The above-mentioned composite amide particles are obtained by mixing the raw materials, granulating, drying, and heating; the heating temperature is 134℃-160℃, and the heating time is 5min-15min; the drying temperature is 75℃-110℃; the moisture content of the dried particles is ≤0.1%.

[0042] After mixing melamine and urea, the mixture is granulated, dried, and then heated and cooled. During the heating process, the amino groups of melamine and urea are molecularly combined, which prevents the material from agglomerating and clumping, resulting in good uniformity and flowability. After cooling, the strength of the composite amide particles is further improved, with a particle strength of over 2N, ensuring that the particles are not damaged during long-distance transportation.

[0043] The drying temperature should be controlled at 75℃-110℃. Excessive drying temperature will cause the composite amide particles to crack and the urea to hydrolyze. The moisture content of the dried particles should be ≤0.1%, which can prevent urea hydrolysis and prevent the composite amide particles from clumping after long-term storage.

[0044] Urea and melamine have significant particle size differences. Rotary disc granulation, drum granulation, roller granulation, and press granulation all require solving the problem of uniform mixing of urea and melamine. Simple mechanical mixing cannot achieve uniform nitrogen content in the composite amide particles. This invention controls the particle size of urea to 20-80 mesh, which can achieve better mixing of urea and melamine. If the urea content is less than 70 wt%, drum granulation, roller granulation, and press granulation are used. If the urea content is too low, melamine and added excipients will clog the nozzles and pipelines due to insufficient flowability. If the urea content is higher than 70 wt%, high-tower granulation is used.

[0045] The present invention will be further described in detail below with reference to specific embodiments, which should not be construed as limiting the scope of protection claimed by the present invention.

[0046] Example 1

[0047] like Figure 1 As shown, this embodiment provides a method for preparing composite amide particles, including the following steps:

[0048] Urea was pulverized and sieved to obtain a powder with a particle size of 60 mesh. Melamine was added to a powder mixer, and then the urea powder was added and mixed for 30 minutes to obtain a mixture. The mixture was then added to a rotary granulator, and the rotary table was tilted at 45°. A 5 wt% PVA aqueous solution was sprayed evenly, with a mass ratio of melamine, urea powder, and PVA aqueous solution of 89:10:1. Under the rotation of the rotary granulator and the adhesive effect of the urea solution, melamine and urea were uniformly compounded to obtain near-spherical particles with a particle diameter of 3.2 mm-3.6 mm. Figure 3 As shown; the material is then dried in a dryer to remove moisture, with the particle moisture content being 0.1%. The dried material is then fed into a hot melt machine and heated at 158°C for 10 minutes to fully melt the urea. The urea and melamine are then fused together. After the hot melt is completed, the particles are cooled in a cooler. After the urea cools and recrystallizes, composite amide particles with a diameter of 3.1 mm to 3.5 mm are formed.

[0049] Example 2

[0050] like Figure 1 As shown, this embodiment provides a method for preparing composite amide particles, including the following steps:

[0051] Urea was pulverized and sieved to obtain a powder with a particle size of 60 mesh. Melamine was added to a powder mixer, and then the urea powder was added and mixed for 25 minutes to obtain a mixture. The mixture was then added to a rotary drum granulator, and a 3wt% PVA aqueous solution was sprayed in. The mass ratio of melamine, urea powder, and PVA aqueous solution was 75:20:5. The mixture was bound together and, under the rotation of the drum, layer by layer, formed spherical particles with a diameter of 3.0 mm to 4.8 mm. Figure 4 As shown; the moisture is then removed in a 95℃ dryer, and the moisture content of the particles is 0.1%. The dried material enters a hot melt machine and is heated at 142℃ for 15 minutes to achieve the fusion of urea, melamine and PVA. After the hot melt is completed, the particles enter a cooler to cool. After the urea cools and recrystallizes, it forms composite amide particles with a diameter of 2.9mm-4.7mm.

[0052] Example 3

[0053] like Figure 1 As shown, this embodiment provides a method for preparing composite amide particles, including the following steps:

[0054] Urea was pulverized and sieved to obtain a powder with a particle size of 60 mesh. Melamine was added to a powder mixer, and then the urea powder was added and mixed for 20 minutes to obtain a mixture. The mixture was then added to a drum granulator, and a 10 wt% diethylene glycol aqueous solution was sprayed into the inlet of the drum granulator. The mass ratio of melamine, urea powder, and PVA aqueous solution was 59:39:2. Under the dissolution and bonding effect of the diethylene glycol solution and the rotation of the drum, near-spherical particles with a diameter of 2.4 mm-2.8 mm were formed. Figure 5 As shown; the material is then dried at low temperature in a dryer until the moisture content of the particles is 0.1%. The dried material is then fed into a hot melt machine and heated at 135°C for 10 minutes to fuse urea, melamine, and diethylene glycol. After the hot melt is completed, the particles are cooled in a cooler. After the urea is cooled and recrystallized, composite amide particles with a diameter of 2.3 mm to 2.7 mm are formed.

[0055] Example 4

[0056] like Figure 1 As shown, this embodiment provides a method for preparing composite amide particles, including the following steps:

[0057] Urea was pulverized and sieved to obtain a powder with a particle size of 40 mesh. 30 wt% melamine was added to a powder mixer, followed by the urea powder and a 5 wt% triethylene glycol aqueous solution. The mass ratio of melamine, urea powder, and PVA aqueous solution was 30:68:2. After mixing for 25 minutes, a mixture was obtained. This mixture was then added to a roller press granulator, where it was extruded into nearly oval particles with a diameter of 2.2 mm-4 mm. Figure 6 As shown, columnar particles can also be formed depending on the molding die. The residual moisture of the urea is then removed in an 85°C dryer, and the moisture content of the particles is 0.1%. The dried material enters a hot melt machine and is heated at 134°C for 5 minutes to fully melt the urea and achieve the fusion of urea, melamine, and triethylene glycol. After the hot melt is completed, the particles enter a cooler to cool. After the urea cools and recrystallizes, amide composite particles with a diameter of 2.1 mm to 3.9 mm are formed.

[0058] Example 5

[0059] like Figure 2 As shown, this embodiment provides a method for preparing composite amide particles, including the following steps:

[0060] Urea was melted at 135℃ and placed in a molten urea stirring tank for later use. Melamine, alumina powder, ultrafine silica, and silane coupling agent KH540 were added to the molten urea stirring tank and mixed with the molten urea for 15 minutes. The mass ratio of melamine, molten urea, alumina powder, ultrafine silica, and silane coupling agent was 10:85:3:1.5:0.5. The mixture was pumped to a rotary nozzle and sprayed from a height. Inside the granulation tower, the granules came into contact with the airflow and formed into spheres. After drying and cooling, the moisture content of the granules was 0.1%, resulting in spherical granules with a diameter of approximately 1.5-2.2 mm. Figure 7 As shown.

[0061] Example 6

[0062] This embodiment provides a method for preparing composite amide particles, which is basically the same as the steps in Example 1. The only difference is that the particle size of the urea powder is 80 mesh, which will reduce the production efficiency and increase the production energy consumption.

[0063] Example 7

[0064] This embodiment provides a method for preparing composite amide particles, which is basically the same as the steps in Example 1. The only difference is that the particle size of the urea powder is 20 mesh. In the mixing step, urea and melamine separate into layers, which increases the difficulty of mixing and extends the mixing time to 42 minutes, thus reducing the production efficiency.

[0065] Example 8

[0066] This embodiment provides a method for preparing composite amide particles, which is basically the same as the steps in Example 2. The mass ratio of melamine, urea powder, and PVA aqueous solution is 72:20:8, which leads to increased cost.

[0067] Example 9

[0068] This embodiment provides a method for preparing composite amide particles, which is basically the same as the steps in Example 4. The drying temperature is 110°C. Urea is prone to hydrolysis, releasing ammonia gas, which poses an environmental problem.

[0069] Example 10

[0070] This embodiment provides a method for preparing composite amide particles, which is basically the same as the steps in Example 4, except that the drying temperature is 75°C, the drying efficiency decreases, the drying time is extended by 3 minutes, and the production efficiency is reduced.

[0071] Comparative Example 1

[0072] This comparative example provides a method for preparing composite amide particles, which is basically the same as the steps in Example 1, except that the heating temperature is 165°C.

[0073] Comparative Example 2

[0074] This comparative example provides a method for preparing composite amide particles, which is basically the same as the steps in Example 4, except that the heating temperature is 130°C.

[0075] Comparative Example 3

[0076] This comparative example provides a method for preparing composite amide particles, which is basically the same as the steps in Example 3, except that the diethylene glycol aqueous solution is replaced with the same mass of melamine.

[0077] Experimental Example 1

[0078] The composite particles prepared in Examples 1-5 and Comparative Examples 1-9 were subjected to particle size testing according to the sieving method of GB / T6003.1, strength testing according to GB / T37918, bulk density testing according to GB / T23771, and Hall flow rate testing according to GB31482 (diameter of 10 mm). The results are shown in the table below.

[0079] Table 1. Performance test results of the composite amide particles prepared in each example and comparative example.

[0080]

[0081]

[0082] As can be seen from the table above, the composite amide particles prepared in Examples 1-10 have a particle size of 1.5-4.7 mm, a compressive strength of 2 N-6 N, and a bulk density of 0.65 g / cm³. 3 -1.4g / cm 3 The Hall flow rate was 15.4 g / s-20.8 g / s. In Comparative Example 1, the heating temperature was 165℃, which caused a polycondensation reaction and deamination to obtain biuret. The composite amide particles contained 0.8 wt% biuret, which did not meet the requirements of relevant industry standards, resulting in poor stability of the subsequent amino resin products. In Comparative Example 2, the heating temperature was lower, the urea did not melt, and the urea and melamine could not be fused together, resulting in low particle strength of only 0.8 N. The hydrogen bond network in the hydroxyl groups of the diethylene glycol aqueous solution can increase viscosity. In Comparative Example 3, the addition of the auxiliary agent diethylene glycol aqueous solution was omitted, resulting in a molding rate of 73%, increased recycled material, decreased efficiency, and lower strength.

[0083] Experiment Example 2

[0084] The preparation of amino resins using the composite amide particles prepared in the above embodiments and comparative examples includes the following steps:

[0085] Two tons of formaldehyde solution with a mass fraction of 37 wt% were added to a 5m... 3In the reaction vessel, under stirring, the composite amide particles prepared in the above examples and comparative examples were added according to a resin solid content of 50 wt%. The pH was adjusted to 7.5, and after reacting at 85°C for 3.5 h, the mixture was cooled to room temperature to obtain the final product.

[0086] The composite amide particles mentioned above were replaced with urea and melamine in the same amounts as in Example 1, serving as control group 1.

[0087] The following table shows the feeding time, material floating time, and on-site powder collection amount during the above-mentioned preparation of amino resin, from feeding to the completion of the reaction and the end of the discharge.

[0088] The stability of the amino resin prepared above was tested, specifically including: immediately after the discharge was completed, 500g of sample was placed in a constant temperature chamber at 25℃, and the stability was determined by the time period during which the resin lost its fluidity. The results are shown in the table below.

[0089] Table 1. Test results of amino resins prepared in each example and comparative example.

[0090]

[0091] As can be seen from the table above, when preparing amino resin from the composite amide particles prepared in Examples 1-10, the feeding time is short, there is no material floating, the reaction rate of the two forms of amino groups (urea and melamine) with formaldehyde is more uniform, and the resin stability is better. The powder in control group 1 has no flowability, a particle size of 0.001 mm-2 mm, and a bulk density of 0.48 g / cm³. 3 Even under impact and vibration, the Hall flow rate could not be measured, the time consumption and material floating time were long, the amount of dust collected on site was large, and the resin properties were poor. In Comparative Example 1, the composite amide particles contained 0.8 wt% biuret, resulting in poor stability of the amino resin. In Comparative Example 2, the composite amide particles had poor strength and powdered during packaging and transportation, resulting in poor stability of the amino resin. In Comparative Example 3, the composite amide particles had a low molding rate and a short stabilization time, resulting in a long time consumption, a large amount of dust collected on site, and poor stability of the amino resin.

[0092] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An amino resin, characterized by, The composite amide particles were prepared using composite amide particles with a diameter of 1 mm-5 mm and a bulk density of 0.65 g / cm³. 3 -1.4g / cm 3 The compressive strength is 2N-6N, and the Hall flow rate is 15.4g / s-20.8g / s; the raw materials of the composite amide particles include melamine, urea, and additives, with the mass ratio of melamine to urea being 1:0.1-9; the content of the additives is 0.1wt%-5wt%. The method for preparing the composite amide particles includes method one or method two, wherein: Method 1 includes the following steps: Melamine is mixed with urea and additives, granulated, dried, and heated at 134℃-160℃ to obtain the final product. In Method 1, the particle size of urea is 40-60 mesh. The additives include at least one of polyvinyl alcohol aqueous solution, diethylene glycol aqueous solution, and triethylene glycol aqueous solution. The urea content is less than 70 wt%, and granulation is carried out by rotary drum granulation, roller granulation, or roller pressing granulation. Method 2 includes the following steps: The mixture of melamine, additives, and molten urea is granulated and dried to obtain the final product. In Method 2, the additives are a mixture of silane coupling agent and silica and / or alumina. The urea content is higher than 70 wt%, and granulation is carried out using a high-tower granulation method. In either method one or method two, the drying temperature is 75℃-110℃; the moisture content of the dried particles is ≤0.1%.

2. The amino resin according to claim 1, characterized in that, The silane coupling agent includes at least one of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, γ-aminopropyltriethoxysilane, vinyltri(2-methoxyethoxy)silane, and vinyltrimethoxysilane.

3. The amino resin according to claim 1, characterized in that, Heating time is 5-15 minutes.

4. The amino resin according to claim 1, characterized in that, The mixing time is 15 min to 42 min.

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