Melamine resin powder toughening granulation method and granulation equipment thereof

Abstract

The invention provides a melamine resin powder toughening granulation method and granulation equipment thereof, and relates to the technical field of thermosetting resin.The melamine resin powder toughening granulation method comprises the following preparation processes that firstly, thermoplastic resin powder is added into a solvent to prepare a thermoplastic resin solution; 2, wrapping inorganic rigid particles with a thermoplastic resin solution to obtain a mixture; 3, the mixture is subjected to spray drying and ground into superfine powder, and then the superfine powder is mixed with melamine powder to obtain composite particles; step 4, adding carboxymethyl cellulose and zinc stearate into the composite particle material, and carrying out double-roller pressing by virtue of a pelletizer, so as to obtain a flaky material; step 5, crushing and granulating the flaky material to obtain granules; sixthly, screening the particles through a screen to obtain finished particles; and 7, re-granulating the unqualified material until qualified uniform melamine resin particles are obtained. Through the technical improvement of the three steps of wrapping, spray drying and grinding, on the basis that the toughness and the flowability of the obtained granules are improved, the uniformity of products formed by compression molding is good.

Description

Technical Field

[0001] This invention relates to the field of thermosetting resin technology, and in particular to a method for toughening and granulating melamine resin powder and its granulation equipment. Background Technology

[0002] Thermosetting plastics are plastics formed by cross-linking and curing, with thermosetting resins as the main component and various necessary additives. Currently, thermosetting plastics are widely used in the manufacture of reinforced plastics, foamed plastics, various electrical molding compounds, cast products, adhesives, and coatings. However, with increasingly stringent national requirements for safety and environmental protection, the powder properties of thermosetting resins can easily cause dust pollution when used as raw materials. Therefore, "granulation of powdered products" has become an inevitable trend in the development of powder post-processing technology. Powder granulation technology is of great significance for reducing dust pollution, improving product physical properties, and meeting production process requirements.

[0003] Powder granulation technology refers to the process of shaping powdered raw materials into solid particles with a specific shape and size and good flowability. Because powdered melamine resin easily generates dust during molding and other processing, causing environmental pollution and inconvenience, it needs to be pre-prepared into granules for further processing. However, as a thermosetting plastic, melamine resin cannot be extruded using high-temperature hot-melt granulation; therefore, granulation must be performed at relatively low temperatures or room temperature. Currently, conventional powder granulation technologies include wet granulation, fluidized bed granulation, pressure molding granulation, spray granulation, and hot-melt molding. Although existing granulation technologies are relatively mature, the inherent properties of melamine resin result in decreased toughness after granulation, affecting its performance.

[0004] Addressing the issue of decreased toughness after granulation of thermosetting melamine resins requires significant efforts in developing toughening methods. Traditional methods for toughening thermosetting resins include: rigid inorganic particle filling, rubber elastomer modification, thermoplastic resin blending modification, interpenetrating network polymers, and liquid crystal polymer modification. Considering cost and the availability of raw materials, rigid inorganic particle filling and thermoplastic resin modification are typically employed. Therefore, researching and improving toughening modifications during thermosetting resin granulation has become a hot topic.

[0005] Chinese invention patent application No. 201710001208.9 discloses a high-toughness melamine resin and its preparation method. The method involves adding an elastomer in powder or emulsion form to the melamine resin to improve its impact strength. The preparation method is as follows: 40-85 parts of melamine-formaldehyde resin prepolymer, 5-50 parts of fiber, 0.1-0.5 parts of curing agent, 5-30 parts of elastomer, and 0.1-1 parts of flow agent are kneaded in a kneader at 25-80℃ for 30-90 minutes, then dried in an oven at 70-130℃ to remove water. The kneaded material is then ball-milled with 3-10 parts of inorganic filler in a ball mill for 4-20 hours to obtain high-toughness melamine powder. Another preparation method involves kneading the prepolymer, fiber, curing agent, and flow agent components in a kneader, then drying them in an oven to remove moisture, resulting in irregular blocky solids. These blocky solids, inorganic fillers, and elastomer powders are then ball-milled in a ball mill according to a specific ratio to obtain high-toughness melamine powder. This method uses the physical blending of fibers and melamine resin to enhance toughness, such as glass fiber, carbon fiber, and plant fibers. However, since melamine plastic products are mostly tableware, and glass fiber and carbon fiber, in addition to plant fibers, have certain safety implications for human health, and existing melamine products already contain plant fibers, such as straw wood fiber, it is difficult to further improve the toughness of the granulated and molded products using this method.

[0006] A paper titled "Synergistic Toughening of Carbon Fiber / Epoxy Composites by Thermoplastic Particles and Inorganic Particles" published in the Journal of Composite Materials, by Liu Xin, Chen Duo, and others, studied the synergistic toughening of carbon fiber / epoxy composites using inorganic nanoparticles and thermoplastic particles. Since epoxy resin and melamine resin are both thermosetting resins, this method can be referenced. However, in the actual granulation and production process, although this method has a certain toughening effect, the processing flowability and uniformity of the granulated particles are not very good.

[0007] Based on the above, the existing melamine resin granulation process suffers from reduced toughness. Furthermore, the technical method of toughening melamine resin granulation by modifying it with rigid inorganic particles and thermoplastic resins has problems such as poor compatibility, poor flowability, and poor product uniformity during the molding process after granulation, and the toughening effect is still not ideal. Summary of the Invention

[0008] To overcome existing problems, this application provides a granulation method and granulation equipment for toughening melamine resin powder. The method involves dissolving thermoplastic material in a solvent and then coating it onto the surface of rigid inorganic particles to form particles with good rigidity and flexibility. After spray drying, small particles are formed, which are then ground into ultrafine powder using a ball mill. The powder is then added to melamine resin powder. This granulation process selects a reasonable roller pressing granulation method, resulting in molded products with high toughness, good flowability, good uniformity, and no heat curing.

[0009] The technical solution adopted by the embodiments of this application to solve its technical problem is:

[0010] A method for toughening and granulating melamine resin powder, wherein in step one, thermoplastic resin powder is added to a solvent and stirred until fully dissolved to obtain a thermoplastic resin solution; the ratio of each raw material is as follows, by weight, 1 part by weight of thermoplastic resin powder and 5-10 parts by weight of solvent.

[0011] Step 2: The thermoplastic resin solution obtained in Step 1 is uniformly coated on the surface of the inorganic rigid particles to obtain a mixture that combines rigidity and flexibility; the ratio of each raw material is as follows: 4-8 parts by weight of thermoplastic resin solution and 5-10 parts by weight of inorganic rigid particles.

[0012] Step 3: Spray dry the mixture obtained in Step 2, then grind it into an ultrafine powder, and then mix it evenly with melamine powder to obtain composite particles; the ratio of each raw material is 1-3 parts by weight of the mixture and 10-20 parts by weight of the melamine powder.

[0013] Step 4: First, add an appropriate amount of carboxymethyl cellulose and zinc stearate to the composite particle material obtained in step 3, and then put it into the granulation equipment. After being pressed by rollers, a thin sheet material is obtained. The ratio of each raw material is as follows: 80-100 parts by weight of composite particle material, 0.5-1 parts by weight of carboxymethyl cellulose, and 1-2 parts by weight of zinc stearate.

[0014] Step 5: First, crush the sheet material obtained in Step 4 using a crusher, and then granulate it using a pelletizer to obtain granules;

[0015] Step Six: Sieve the granules obtained in Step Five using a sieve to obtain the finished granules;

[0016] Step 7 involves returning the unqualified powder or particles from Step 6 to Step 4 for granulation until all particles are granulated into qualified, uniform melamine resin particles, thus achieving toughening granulation of melamine resin powder.

[0017] Melamine resin possesses advantages such as high-temperature inertness, high activity, arc resistance, high hardness, and good dimensional stability, making it highly valuable for various applications. However, melamine resin powder is prone to contamination, making granulation a desirable option. But as a thermosetting resin, the biggest weakness of its cross-linked network structure is its brittleness after curing, poor impact and stress crack resistance, and constrained plastic deformation, making heat granulation difficult.

[0018] It is well known that high-performance thermoplastic resins with high modulus and high glass transition temperature can effectively toughen thermosetting resins. Due to the high glass transition temperature of thermoplastic resins, the modified materials have good heat resistance. Especially during the curing process of thermosetting resins, the optimal toughening effect can be achieved by controlling the reaction-induced phase separation to form a bicontinuous phase. However, it is difficult to use thermoplastic processing methods to toughen thermosetting granules.

[0019] As a preferred embodiment of the present invention, the thermoplastic resin in step one is polystyrene; the solvent is toluene. The principle of rigid inorganic particle toughening of thermosetting resin lies in the fact that, due to the presence of rigid particles, when the thermosetting resin is subjected to external force, a stress concentration effect occurs, causing the particles to induce numerous crazes, forcing the matrix surrounding the particles to undergo plastic deformation and absorb a large amount of impact energy. Simultaneously, the presence of rigid particles can also hinder the development of crazes, passivating and terminating them, thus achieving a toughening effect. For rigid inorganic particle-reinforced polymers, the size and size distribution of the dispersed particles must be appropriate, and good interfacial bonding between the particles and the resin matrix must be ensured to facilitate good stress transfer. As a preferred embodiment of the present invention, the inorganic rigid particles in step two are at least one of nano-sized silica, alumina, and montmorillonite.

[0020] When thermoplastic resins and rigid inorganic particles are directly physical blended with thermosetting resins for modification, uniform granulation cannot be achieved, resulting in poor flowability and inadequate toughening effect. This invention creatively coats a fully dissolved thermoplastic resin solution onto the surface of rigid particles, which are then spray-dried to form small particles. These particles are then ground into ultrafine powder using a ball mill, and subsequently added to melamine resin powder for roll pressing granulation. This achieves toughening granulation of the melamine resin powder, rather than solidifying the resin powder. Preferably, in step three, the ultrafine powder has a particle size of 0.1-8 μm, and the melamine powder has a particle size of 0.1-50 μm.

[0021] This invention involves adding appropriate amounts of carboxymethyl cellulose and zinc stearate during the granulation process of ultrafine powder combining rigidity and flexibility with melamine resin powder. Carboxymethyl cellulose helps control moisture evaporation caused by equipment operation and high-temperature friction with the granules during granulation, thus retaining moisture and ensuring granulation quality. Zinc stearate, a common lubricant and release agent, provides excellent lubrication. Using appropriate granulation equipment throughout the process further ensures the toughening effect, uniformity, and flowability of the molded products. Preferably, step four uses a double-roller dry extrusion granulator, with the extrusion pressure adjusted by a hydraulic cylinder.

[0022] During the operation of the granulation equipment, parameters such as pressure and speed must be effectively controlled. By adjusting the pressure, the compactness and density of the flaky material can be controlled, which plays a certain role in facilitating subsequent crushing and granulation by the crusher. In step four, the pressure of the roller pressing is 5-15 MPa.

[0023] Finally, the flake material obtained from the granulation equipment is crushed by a crusher and granulated by a granulator. The finished particles with suitable and uniform size are then screened through a screen. At the same time, unqualified powder or particles are re-granulated, which not only effectively ensures the quality of the finished product after granulation, but also avoids material waste. The particle size of the finished particles in step six is ​​2-6mm.

[0024] Thermoplastic resin powder is dissolved in a suitable solvent to form a solution; the solution is coated on the surface of inorganic rigid particles to form a mixture combining rigidity and flexibility; the mixture is spray-dried, ground into ultrafine powder, and then mixed again with melamine powder to form composite particles; the composite particles are fed into a granulation device with appropriate amounts of carboxymethyl cellulose and zinc stearate, and after operation, they are pressed into thin flakes; the flakes are crushed by a crusher and granulated by a granulator; the finished particles are screened out using a sieve; unqualified powder or particles are re-granulated and screened, and finally all are granulated into qualified uniform particles.

[0025] It includes a granulation assembly for granulating melamine resin powder and a collection hopper disposed at the top of the granulation assembly, wherein the collection hopper and the granulation assembly are detachably installed.

[0026] The hopper is equipped with a protective cylinder at its top. The protective cylinder has a hollow structure and a limiting plate at one end. The protective cylinder is inserted into the hopper, and the limiting plate is located on the upper surface of the hopper to limit the movement of the protective cylinder. The top and bottom of the protective cylinder are truncated cone structures with variable cross-sections. The cross-sectional diameter of the bottom of the protective cylinder is larger than that of the hopper. When the granulation equipment is not in use, the top of the protective cylinder is inserted into the hopper, and the limiting plate at the bottom mutually limits the movement of the protective cylinder with the hopper, thus protecting the hopper and preventing dust and impurities from entering. Furthermore, the protective cylinder can be separated from the hopper and placed on the discharge plate side to receive materials, thus extending the overall service life of the structure.

[0027] Preferably, the granulation assembly includes a granulation box connected to the collecting hopper, the granulation box having a plurality of feeding holes inside, a roller shaft on the upper surface of the inner wall of the granulation box, a feeding box at the bottom of the granulation box, and a connecting seat at the bottom of the feeding box.

[0028] Preferably, the granulation component has a start button on its side wall. The start button is electrically connected to a power source. The start button can start the motor inside the granulation component, which in turn drives the roller inside the granulation component to rotate.

[0029] Preferably, the granulation component has a discharge plate on the side wall of the start button. After the material is squeezed by the roller, the squeezed material enters the interior of the discharge plate through the feeding hole and is finally discharged from the discharge plate.

[0030] Preferably, the granulation component has a base at its bottom, and a motor is installed inside the base to drive the roller to rotate. The composite particles are fed into the hopper with an appropriate amount of carboxymethyl cellulose and zinc stearate. The roller then extrudes the composite particles through the extrusion hole and finally discharges them from the discharge plate.

[0031] The advantages of the embodiments of this application are:

[0032] 1. This invention involves a granulation process in which thermoplastic materials are first dissolved in a solvent and then coated onto the surface of rigid inorganic particles to form particles with good rigidity and flexibility. These particles are then spray-dried to form small granules, ground into ultrafine powder using a ball mill, and then added to melamine resin powder. This process employs a reasonable roller pressing granulation method, resulting in molded products with high toughness, good flowability, good uniformity, and no heat curing.

[0033] 2. This invention employs a method for toughening and granulating melamine resin powder by encapsulating rigid inorganic particles with thermoplastic resin and then mixing them with melamine resin. Furthermore, by studying the characteristics of melamine resin, a reasonable granulation equipment and granulation process were selected to ensure granulation quality and reduce environmental pollution during transportation. Attached Figure Description

[0034] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0035] Figure 1 This is a schematic diagram of the overall structure of the melamine resin powder toughening granulation method and granulation equipment of the present invention;

[0036] Figure 2 This is a top view schematic diagram of the melamine resin powder toughening granulation method and granulation equipment of the present invention.

[0037] Figure 3 This is a schematic diagram of the overall structure of the protective cylinder in the melamine resin powder toughening granulation method and granulation equipment of the present invention.

[0038] Figure 4 This is a schematic diagram of the overall structure of the melamine resin powder toughening granulation method and granulation equipment of the present invention, after removing the protective cylinder.

[0039] Figure 5 This is a top view schematic diagram of the melamine resin powder toughening granulation method and granulation equipment of the present invention, showing the removal of the protective cylinder.

[0040] Explanation of key figure labels:

[0041] 1. Base; 2. Granulation assembly; 3. Protective cylinder; 4. Discharge plate; 5. Limiting plate; 6. Collecting hopper; 7. Granulation box; 8. Feeding box; 9. Connecting seat; 10. Start button; 11. Feeding hole; 12. Roller. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. In addition, for the sake of convenience, the terms "upper," "lower," "left," and "right" are equivalent to the upper, lower, left, and right directions of the accompanying drawings themselves, and the terms "first," "second," etc., are used for descriptive purposes and have no other special meaning.

[0043] This application provides a granulation method and equipment for toughening melamine resin powder, addressing problems in the prior art. The invention involves dissolving thermoplastic materials in a solvent and then coating them onto the surface of rigid inorganic particles to form particles with both rigidity and flexibility. These particles are then spray-dried to form small granules, ground into ultrafine powder using a ball mill, and finally added to melamine resin powder. A suitable roller pressing granulation process is employed, resulting in molded products with high toughness, good flowability, and good uniformity, without thermal curing. This invention uses a method of toughening melamine resin powder by coating rigid inorganic particles with thermoplastic resin and then mixing them with melamine resin. Furthermore, by studying the characteristics of melamine resin, a suitable granulation equipment and process are selected, ensuring granulation quality and reducing environmental pollution during transportation.

[0044] The technical solution in this application is to solve the above problems, and the overall approach is as follows:

[0045] Example 1

[0046] Step 1: First, add the thermoplastic resin powder to the solvent and stir until fully dissolved to obtain a thermoplastic resin solution; the thermoplastic resin is polystyrene; the solvent is toluene; the ratio of each raw material is, by weight, 1 part by weight of thermoplastic resin powder and 7 parts by weight of solvent.

[0047] Step 2: The thermoplastic resin solution obtained in Step 1 is uniformly coated on the surface of the inorganic rigid particles to obtain a mixture that combines rigidity and flexibility; the inorganic rigid particles are nano-silica; the ratio of each raw material is 5 parts by weight of thermoplastic resin solution and 7 parts by weight of inorganic rigid particles.

[0048] Step 3: Spray dry the mixture obtained in Step 3, then grind it into an ultrafine powder, and then mix it evenly with melamine powder to obtain composite particles; the average particle size of the ultrafine powder is 5 μm; the average particle size of the melamine powder is 30 μm; the ratio of each raw material is 2 parts by weight of the mixture and 16 parts by weight of the melamine powder.

[0049] Step four involves adding appropriate amounts of carboxymethyl cellulose and zinc stearate to the composite granules obtained in step three, then feeding them into a granulation device. After being pressed by rollers, thin flakes are obtained. The granulation device uses a roller-type dry extrusion granulator. The roller pressing pressure is 11 MPa. The proportions of each raw material are as follows: 88 parts by weight of composite granules, 0.5 parts by weight of carboxymethyl cellulose, and 1.6 parts by weight of zinc stearate.

[0050] Step 5: First, crush the sheet material obtained in Step 4 using a crusher, and then granulate it using a pelletizer to obtain granules;

[0051] Step 6: The particles obtained in Step 5 are sieved using a sieve to obtain finished particles; the average particle size of the finished particles is 5 mm.

[0052] Step 7 involves returning the unqualified powder or particles from Step 6 to Step 4 for granulation until all particles are granulated into qualified, uniform melamine resin particles, thus achieving toughening granulation of melamine resin powder.

[0053] Example 2

[0054] Step 1: First, add the thermoplastic resin powder to the solvent and stir until fully dissolved to obtain a thermoplastic resin solution; the thermoplastic resin is polystyrene; the solvent is toluene; the ratio of each raw material is, by weight, 1 part by weight of thermoplastic resin powder and 9 parts by weight of solvent.

[0055] Step 2: The thermoplastic resin solution obtained in Step 1 is uniformly coated on the surface of the inorganic rigid particles to obtain a mixture that combines rigidity and flexibility; the inorganic rigid particles are nano-alumina; the ratio of each raw material is as follows: 5 parts by weight of thermoplastic resin solution and 9 parts by weight of inorganic rigid particles.

[0056] Step 3: Spray dry the mixture obtained in Step 2, then grind it into an ultrafine powder, and then mix it evenly with melamine powder to obtain composite particles; the average particle size of the ultrafine powder is 2μm; the average particle size of the melamine powder is 10μm; the ratio of each raw material is 2 parts by weight of the mixture and 18 parts by weight of the melamine powder.

[0057] Step four involves adding appropriate amounts of carboxymethyl cellulose and zinc stearate to the composite granules obtained in step three, then feeding them into a granulation equipment. After being pressed by rollers, thin flakes are obtained. The granulation equipment uses a roller-type dry extrusion granulator. During roller pressing, the pressure of the rollers is 8 MPa. The proportions of each raw material are as follows: 95 parts by weight of composite granules, 0.5 parts by weight of carboxymethyl cellulose, and 1.2 parts by weight of zinc stearate.

[0058] Step 5: First, crush the sheet material obtained in Step 4 using a crusher, and then granulate it using a pelletizer to obtain granules;

[0059] Step 6: The particles obtained in Step 5 are sieved using a sieve to obtain finished particles; the average particle size of the finished particles is 3mm.

[0060] Step 7 involves returning the unqualified powder or particles from Step 6 to Step 4 for granulation until all particles are granulated into qualified, uniform melamine resin particles, thus achieving toughening granulation of melamine resin powder.

[0061] Example 3

[0062] Step 1: First, add the thermoplastic resin powder to the solvent and stir until fully dissolved to obtain a thermoplastic resin solution; the thermoplastic resin is polystyrene; the solvent is toluene; the ratio of each raw material is, by weight, 1 part by weight of thermoplastic resin powder and 6 parts by weight of solvent.

[0063] Step 2: The thermoplastic resin solution obtained in Step 1 is uniformly coated on the surface of the inorganic rigid particles to obtain a mixture that combines rigidity and flexibility; the inorganic rigid particles are nano-montmorillonite; the ratio of each raw material is 7 parts by weight of thermoplastic resin solution and 6 parts by weight of inorganic rigid particles.

[0064] Step 3: Spray dry the mixture obtained in Step 2, then grind it into an ultrafine powder, and then mix it evenly with melamine powder to obtain composite particles; the average particle size of the ultrafine powder is 6μm; the average particle size of the melamine powder is 40μm; the ratio of each raw material is 3 parts by weight of the mixture and 13 parts by weight of the melamine powder.

[0065] Step four involves adding appropriate amounts of carboxymethyl cellulose and zinc stearate to the composite granules obtained in step three, then feeding them into a granulation equipment. After being pressed by rollers, thin flakes are obtained. The granulation equipment uses a roller-type dry extrusion granulator. During roller pressing, the pressure is 13 MPa. The proportions of each raw material are as follows: 85 parts by weight of composite granules, 0.5 parts by weight of carboxymethyl cellulose, and 1.8 parts by weight of zinc stearate.

[0066] Step 5: First, crush the sheet material obtained in Step 4 using a crusher, and then granulate it using a pelletizer to obtain granules;

[0067] Step 6: The particles obtained in Step 5 are sieved using a sieve to obtain finished particles; the average particle size of the finished particles is 5 mm.

[0068] Step 7 involves returning the unqualified powder or particles from Step 6 to Step 4 for granulation until all particles are granulated into qualified, uniform melamine resin particles, thus achieving toughening granulation of melamine resin powder.

[0069] Example 4

[0070] Step 1: First, add the thermoplastic resin powder to the solvent and stir until fully dissolved to obtain a thermoplastic resin solution; the thermoplastic resin is polystyrene; the solvent is toluene; the ratio of each raw material is, by weight, 1 part by weight of thermoplastic resin powder and 10 parts by weight of solvent.

[0071] Step 2: The thermoplastic resin solution obtained in Step 1 is uniformly coated on the surface of inorganic rigid particles to obtain a mixture that combines rigidity and flexibility; the inorganic rigid particles are nano-silica; the ratio of each raw material is as follows: 4 parts by weight of thermoplastic resin solution and 10 parts by weight of inorganic rigid particles.

[0072] Step 3: Spray dry the mixture obtained in Step 2, then grind it into an ultrafine powder, and then mix it evenly with melamine powder to obtain composite particles; the average particle size of the ultrafine powder is 0.1 μm; the average particle size of the melamine powder is 0.1 μm; the ratio of each raw material is 3 parts by weight of the mixture and 20 parts by weight of the melamine powder.

[0073] Step 4: First, add appropriate amounts of carboxymethyl cellulose and zinc stearate to the composite granules obtained in Step 3, then feed them into the granulation equipment. After being pressed by rollers, thin flakes are obtained. The granulation equipment adopts a roller dry extrusion granulator. During roller pressing, the pressure of roller pressing is 5 MPa. The proportion of each raw material is as follows: 100 parts by weight of composite granules, 0.5 parts by weight of carboxymethyl cellulose, and 1 part by weight of zinc stearate.

[0074] Step 5: First, crush the sheet material obtained in Step 4 using a crusher, and then granulate it using a pelletizer to obtain granules;

[0075] Step 6: The particles obtained in Step 5 are sieved using a sieve to obtain finished particles; the average particle size of the finished particles is 2 mm.

[0076] Step 7 involves returning the unqualified powder or particles from Step 6 to Step 4 for granulation until all particles are granulated into qualified, uniform melamine resin particles, thus achieving toughening granulation of melamine resin powder.

[0077] Example 5

[0078] Step 1: First, add the thermoplastic resin powder to the solvent and stir until fully dissolved to obtain a thermoplastic resin solution; the thermoplastic resin is polystyrene; the solvent is toluene; the ratio of each raw material is, by weight, 1 part by weight of thermoplastic resin powder and 5 parts by weight of solvent.

[0079] Step 2: The thermoplastic resin solution obtained in Step 1 is uniformly coated on the surface of the inorganic rigid particles to obtain a mixture that combines rigidity and flexibility; the inorganic rigid particles are nano-alumina; the ratio of each raw material is as follows: 8 parts by weight of thermoplastic resin solution and 5 parts by weight of inorganic rigid particles.

[0080] Step 3: Spray dry the mixture obtained in Step 2, then grind it into an ultrafine powder, and then mix it evenly with melamine powder to obtain composite particles; the average particle size of the ultrafine powder is 8μm; the average particle size of the melamine powder is 50μm; the ratio of each raw material is 3 parts by weight of the mixture and 10 parts by weight of the melamine powder.

[0081] Step 4: First, add appropriate amounts of carboxymethyl cellulose and zinc stearate to the composite granules obtained in Step 3, then feed them into the granulation equipment. After being pressed by rollers, thin flakes are obtained. The granulation equipment adopts a roller dry extrusion granulator. During roller pressing, the pressure of roller pressing is 15 MPa. The proportion of each raw material is as follows: 80 parts by weight of composite granules, 0.5 parts by weight of carboxymethyl cellulose, and 2 parts by weight of zinc stearate.

[0082] Step 5: First, crush the sheet material obtained in Step 4 using a crusher, and then granulate it using a pelletizer to obtain granules;

[0083] Step 6: The particles obtained in Step 5 are sieved using a sieve to obtain finished particles; the average particle size of the finished particles is 6 mm.

[0084] Step 7 involves returning the unqualified powder or particles from Step 6 to Step 4 for granulation until all particles are granulated into qualified, uniform melamine resin particles, thus achieving toughening granulation of melamine resin powder.

[0085] Example 6

[0086] Step 1: First, add the thermoplastic resin powder to the solvent and stir until fully dissolved to obtain a thermoplastic resin solution; the thermoplastic resin is polystyrene; the solvent is toluene; the ratio of each raw material is, by weight, 1 part by weight of thermoplastic resin powder and 7.5 parts by weight of solvent.

[0087] Step 2: The thermoplastic resin solution obtained in Step 1 is uniformly coated on the surface of inorganic rigid particles to obtain a mixture that combines rigidity and flexibility; the inorganic rigid particles are nano-montmorillonite; the ratio of each raw material is as follows: 6 parts by weight of thermoplastic resin solution and 7.5 parts by weight of inorganic rigid particles.

[0088] Step 3: Spray dry the mixture obtained in Step 2, then grind it into an ultrafine powder, and then mix it evenly with melamine powder to obtain composite particles; the average particle size of the ultrafine powder is 4μm; the average particle size of the melamine powder is 25μm; the ratio of each raw material is 2.5 parts by weight of the mixture and 15 parts by weight of the melamine powder.

[0089] Step four involves adding appropriate amounts of carboxymethyl cellulose and zinc stearate to the composite granules obtained in step three, then feeding them into a granulation equipment. After being pressed by rollers, thin flakes are obtained. The granulation equipment uses a roller-type dry extrusion granulator. During roller pressing, the pressure is 10 MPa. The proportions of each raw material are as follows: 90 parts by weight of composite granules, 0.8 parts by weight of carboxymethyl cellulose, and 1.5 parts by weight of zinc stearate.

[0090] Step 5: First, crush the sheet material obtained in Step 4 using a crusher, and then granulate it using a pelletizer to obtain granules;

[0091] Step 6: The particles obtained in Step 5 are sieved using a sieve to obtain finished particles; the average particle size of the finished particles is 4 mm.

[0092] Step 7 involves returning the unqualified powder or particles from Step 6 to Step 4 for granulation until all particles are granulated into qualified, uniform melamine resin particles, thus achieving toughening granulation of melamine resin powder.

[0093] Example 7

[0094] Step 1: Grind 0.7 parts by weight of polystyrene and 7.5 parts by weight of inorganic rigid particles into ultrafine powder, and then mix it evenly with melamine powder to obtain composite particle material; the average particle size of the ultrafine powder is 4μm; the average particle size of the melamine powder is 25μm; the ratio of each raw material is 2.5 parts by weight of the mixture and 15 parts by weight of melamine powder.

[0095] Step four involves adding appropriate amounts of carboxymethyl cellulose and zinc stearate to the composite granules obtained in step three, then feeding them into a granulation equipment. After being pressed by rollers, thin flakes are obtained. The granulation equipment uses a roller-type dry extrusion granulator. During roller pressing, the pressure is 10 MPa. The proportions of each raw material are as follows: 90 parts by weight of composite granules, 0.8 parts by weight of carboxymethyl cellulose, and 1.5 parts by weight of zinc stearate.

[0096] Step 5: First, crush the sheet material obtained in Step 4 using a crusher, and then granulate it using a pelletizer to obtain granules;

[0097] Step 6: The particles obtained in Step 5 are sieved using a sieve to obtain finished particles; the average particle size of the finished particles is 4 mm.

[0098] Step 7 involves returning the unqualified powder or particles from Step 6 to Step 4 for granulation until all particles are granulated into qualified, uniform melamine resin particles, thus achieving toughening granulation of melamine resin powder.

[0099] In Example 7, inorganic rigid particles and thermoplastic resin were directly ground and then mixed with melamine resin powder for granulation. Other preparation conditions were the same as in Example 6.

[0100] Example 8

[0101] Step 1: First, add the thermoplastic resin powder to the solvent and stir until fully dissolved to obtain a thermoplastic resin solution; the thermoplastic resin is polystyrene; the solvent is toluene; the ratio of each raw material is, by weight, 1 part by weight of thermoplastic resin powder and 7.5 parts by weight of solvent.

[0102] Step 2: The thermoplastic resin solution obtained in Step 1 is uniformly coated on the surface of inorganic rigid particles to obtain a mixture that combines rigidity and flexibility; the inorganic rigid particles are nano-montmorillonite; the ratio of each raw material is as follows: 6 parts by weight of thermoplastic resin solution and 7.5 parts by weight of inorganic rigid particles.

[0103] Step 3: Spray dry the mixture obtained in Step 2, then grind it into an ultrafine powder, and then mix it evenly with melamine powder to obtain composite particles; the average particle size of the ultrafine powder is 4μm; the average particle size of the melamine powder is 25μm; the ratio of each raw material is 2.5 parts by weight of the mixture and 15 parts by weight of the melamine powder.

[0104] Step 4: First, the composite particle material obtained in Step 3 is fed into the granulation equipment and pressed by rollers to obtain thin sheet material; the granulation equipment adopts a roller dry extrusion granulator; during roller pressing, the pressure of roller pressing is 10MPa;

[0105] Step 5: First, crush the sheet material obtained in Step 4 using a crusher, and then granulate it using a pelletizer to obtain granules;

[0106] Step 6: The particles obtained in Step 5 are sieved using a sieve to obtain finished particles; the average particle size of the finished particles is 4 mm.

[0107] Step 7 involves returning the unqualified powder or particles from Step 6 to Step 4 for granulation until all particles are granulated into qualified, uniform melamine resin particles, thus achieving toughening granulation of melamine resin powder.

[0108] Example 8 did not include carboxymethyl cellulose and zinc stearate, and the other preparation conditions were the same as in Example 6.

[0109] Example 9

[0110] It includes a granulation component 2 for granulating melamine resin powder and a collection hopper 6 disposed at the top of the granulation component 2. The collection hopper 6 and the granulation component 2 are detachably installed.

[0111] The top of the hopper 6 is equipped with a protective cylinder 3, which is hollow. One end of the protective cylinder 3 is equipped with a limiting plate 5. The protective cylinder 3 is inserted into the hopper 6, and the limiting plate 5 is located on the upper surface of the hopper 6 to limit the movement of the protective cylinder 3. The top and bottom of the protective cylinder 3 are truncated cone structures with variable cross-sections. The cross-sectional diameter of the bottom of the protective cylinder 3 is larger than that of the hopper 6. When the granulation equipment is not in use, the top of the protective cylinder 3 is inserted into the hopper 6, and the limiting plate 5 at the bottom limits the movement of the protective cylinder 3 and the hopper 6, thus protecting the hopper 6 and preventing dust and impurities from entering. At the same time, the protective cylinder 5 can be separated from the hopper 6 and placed on the side of the discharge plate 4 to receive materials, thereby improving the service life of the overall structure.

[0112] The granulation assembly 2 includes a granulation box 7 connected to the collection hopper 6. The granulation box 7 has several discharge holes 11 inside. The upper surface of the inner wall of the granulation box 7 is provided with a roller 12. The bottom end of the granulation box 7 is provided with a discharge box 8. The bottom end of the discharge box 8 is provided with a connecting seat 9.

[0113] The side wall of the granulation component 2 is provided with a start button 10, which is electrically connected to the power supply. The start button 10 can start the motor inside the granulation component 2, which drives the roller 12 inside the granulation component 2 to rotate.

[0114] The granulation component 2 is provided with a discharge plate 4 on the side wall of the start button 10. After the material is squeezed by the roller 12, the squeezed material enters the interior of the discharge plate 4 through the discharge hole 11 and is finally discharged from the discharge plate 4.

[0115] The granulation component 2 is equipped with a base 1 at the bottom. The base 1 is equipped with a motor to drive the roller 12 to rotate. The composite particle material is fed into the hopper 6 with an appropriate amount of carboxymethyl cellulose and zinc stearate. The roller 12 is used to press the composite particle material with an appropriate amount of carboxymethyl cellulose and zinc stearate into the hopper 6. The material is then extruded through the discharge hole 11 and finally discharged from the discharge plate 4.

[0116] By adopting the above technical solution:

[0117] The top and bottom of the protective cylinder 3 are truncated cone structures with variable cross-sections. The cross-sectional diameter of the bottom of the protective cylinder 3 is larger than that of the hopper 6. When the granulation equipment is not in use, the top of the protective cylinder 3 is inserted into the hopper 6 and mutually limited by the bottom limiting plate 5, which protects the hopper 6 and prevents dust and impurities from entering. At the same time, the protective cylinder 3 can be placed on the side of the discharge plate 4 to receive materials, which improves the service life of the overall structure.

[0118] The testing methods for performance indicators are as follows:

[0119] Impact strength: A certain amount of the products obtained by granulation according to the methods of Examples 1-6 and 7-8 were used to press test specimens using a flat vulcanizing apparatus at 165°C and 130 bar on the upper and lower pressure plates. The unnotched impact strength of the simply supported beam was tested according to GB / T10431.1-2008. As shown in Table 1.

[0120] Flowability test: 100g of each of the granules obtained by the methods of Examples 1-6 and Comparative Examples 1-2 were taken and pressed for 35s on a flatbed press at 170℃ and 10kg. After molding, the diameter of the pressed sample was measured with a ruler, as shown in Table 1. Figure 2 As shown, the schematic diagram of the press used to test the processing fluidity and the extensibility diagram of the granules after being pressed show that the larger the diameter, the better the fluidity.

[0121] Table 1:

[0122]

[0123] As shown in Table 1, the method of the present invention can effectively enhance the processing fluidity while improving the toughness of melamine resin powder. Example 7 directly uses the traditional blending method, resulting in a product with poor toughness and processing fluidity; Example 8 did not add carboxymethyl cellulose and zinc stearate during granulation, and the fluidity was significantly reduced.

[0124] Working principle: Thermoplastic resin powder is dissolved in a suitable solvent to form a solution. The solution is then coated on the surface of inorganic rigid particles to form a mixture combining rigidity and flexibility. The mixture is then spray-dried and ground into an ultrafine powder, which is then mixed with melamine powder to form composite particles. The composite particles are then fed into a granulation device with appropriate amounts of carboxymethyl cellulose and zinc stearate. After operation, the particles are pressed into thin flakes. The flakes are crushed by a crusher and granulated by a granulator. The finished particles are sieved out. Unqualified powder or particles are re-granulated and sieved. Finally, all particles are granulated into qualified and uniform particles.

[0125] Remove the protective cylinder 3 at the top of the hopper 6, then press the start button 10. The granulation component 2 rotates the roller 12 inside under the drive of the motor. Then, add an appropriate amount of carboxymethyl cellulose and zinc stearate to the composite particle material and feed it into the hopper 6. The roller 12 presses the composite particle material with an appropriate amount of carboxymethyl cellulose and zinc stearate, and it is then extruded through the discharge hole 11. Finally, it is discharged from the discharge plate 4.

[0126] Finally, it should be noted that the above embodiments are merely examples for clearly illustrating the present invention 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. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for toughening and granulating melamine resin powder, characterized in that, The melamine resin powder toughening granulation method is as follows: Step 1: First, add the thermoplastic resin powder to the solvent and stir until fully dissolved to obtain a thermoplastic resin solution. The ratio of each raw material is as follows: 1 part by weight of thermoplastic resin powder and 5-10 parts by weight of solvent. Step 2: Coat the surface of the inorganic rigid particles with the thermoplastic resin solution obtained in Step 1 to obtain a mixture that combines rigidity and flexibility; the ratio of each raw material is as follows: 4-8 parts by weight of thermoplastic resin solution and 5-10 parts by weight of inorganic rigid particles. Step 3: Spray dry the mixture obtained in Step 2, then grind it into an ultrafine powder, and then mix it evenly with melamine powder to obtain composite particles; the ratio of each raw material is 1-3 parts by weight of the mixture and 10-20 parts by weight of the melamine powder. Step 4: Add carboxymethyl cellulose and zinc stearate to the composite granules obtained in Step 3, and then feed them into the granulation equipment. After being pressed by rollers, thin flakes are obtained. The proportions of each raw material are as follows, by weight: 80-100 parts by weight of composite particles, 0.5-1 parts by weight of carboxymethyl cellulose, and 1-2 parts by weight of zinc stearate. Step 5: Crush the sheet material obtained in Step 4 using a crusher, and then granulate it using a pelletizer to obtain granules; Step 6: Sieve the granules obtained in Step 5 using a sieve to obtain the finished granules; Step 7: Return the unqualified powder or particles from Step 6 to Step 4 for granulation until all the granules are finally granulated into qualified uniform melamine resin particles, thus achieving toughening granulation of melamine resin powder.

2. The method for toughening and granulating melamine resin powder as described in claim 1, characterized in that, The thermoplastic resin used in step one is polystyrene.

3. The method for toughening and granulating melamine resin powder as described in claim 1, characterized in that, The solvent in step one is toluene.

4. The method for toughening and granulating melamine resin powder as described in claim 1, characterized in that, In step two, the inorganic rigid particles are at least one of nanoscale silicon dioxide, aluminum oxide, and montmorillonite.

5. The method for toughening and granulating melamine resin powder as described in claim 1, characterized in that, The particle size of the ultrafine powder in step three is 0.1-8 μm; the particle size of the melamine powder is 0.1-50 μm.

6. The method for toughening and granulating melamine resin powder as described in claim 1, characterized in that, In step four, the granulation equipment used is a double-roll dry extrusion granulator.

7. The method for toughening and granulating melamine resin powder as described in claim 1, characterized in that, In step four, the pressure of the roller pressing is 5-15 MPa.

8. The method for toughening and granulating melamine resin powder as described in claim 1, characterized in that, The particle size of the finished product particles in step six is ​​2-6 mm.

9. A melamine resin powder toughening and granulation device, characterized in that, The granulation equipment is applicable to the toughening granulation method of melamine resin powder according to any one of claims 1-8, including a granulation component (2) for granulating melamine resin powder and a collection hopper (6) disposed at the top of the granulation component (2), wherein the collection hopper (6) and the granulation component (2) are detachably installed. The top of the hopper (6) is provided with a protective cylinder (3), which is hollow. One end of the protective cylinder (3) is provided with a limiting plate (5). The protective cylinder (3) is inserted into the hopper (6). The limiting plate (5) is located on the upper surface of the hopper (6) and is used to limit the protective cylinder (3).

10. The melamine resin powder toughening and granulation equipment as described in claim 9, characterized in that, The granulation assembly (2) includes a granulation box (7) connected to the collection hopper (6). The granulation box (7) has several discharge holes (11) inside. The upper surface of the inner wall of the granulation box (7) is provided with a roller (12). The bottom end of the granulation box (7) is provided with a discharge box (8). The bottom end of the discharge box (8) is provided with a connecting seat (9). The side wall of the granulation assembly (2) is provided with a start button (10). The side wall of the granulation assembly (2) located on the start button (10) is provided with a discharge plate (4). The bottom end of the granulation assembly (2) is provided with a base (1). The base (1) is provided with a motor inside, which is used to drive the roller (12) to rotate.

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