Coating agent for expandable polystyrene particles as well as preparation method and application of coating agent

Abstract

The invention relates to the field of high polymer material processing, and particularly discloses a coating agent for expandable polystyrene particles as well as a preparation method and application of the coating agent. The invention discloses a coating agent for expandable polystyrene particles. The coating agent is prepared from the following raw materials in parts by weight: 20-30 parts of a film-forming agent; 30 to 40 parts of an emulsifier; 30 to 35 parts of a lubricant; 10 to 15 parts of an impermeable material; the emulsifier comprises polyglycerol decastearate and glyceryl monostearate according to a weight ratio of 1: (1-2), the impermeable material is prepared from a functional monomer and activated graphene, and the functional monomer comprises 2-acrylamide-2-methylpropanesulfonic acid and / or sodium p-styrenesulfonate. The product provided by the invention can be used for apparent protection of the EPS particles, can effectively improve the adhesion and caking problems of the EPS particles in the foaming process, and greatly reduces the possibility of the situation that the coating part is damaged in the friction process of different EPS particles.

Description

Technical Field

[0001] This application relates to the technical field of polymer material processing, and particularly relates to a coating agent for expandable polystyrene particles, a preparation method thereof, and an application thereof. Background Art

[0002] Expandable polystyrene (EPS) particles are a kind of polystyrene product added with a foaming agent, and their appearance is colorless and transparent bead-like particles. EPS particles are widely used in scenarios such as cushioning packaging materials and building insulation boards (such as EPS insulation boards). Their lightweight characteristics can reduce transportation costs and improve thermal insulation performance. Since EPS particles are prone to adhesion and caking between particles during foaming, this will cause appearance defects on the surface of the final foamed material, affecting aesthetics and service life. Therefore, some researchers have proposed to carry out coating protection on the surface of EPS particles to ensure the dispersion of EPS particles during storage and transportation, and optimize the apparent integrity of the final foamed material.

[0003] The current coating protectant is composed of a film-forming agent, a lubricant, and an emulsifier. However, with actual use, it is found that the surface of EPS particles itself has unevenness problems. Therefore, it is difficult to ensure good improvement of the friction and adhesion phenomena between particles only by the lubrication effect of the existing lubricant, and the coating may still be partially damaged during the friction between different particles. Therefore, there is still a large room for improvement in the lubrication effect and anti-adhesion effect of the coating agent for expandable polystyrene particles. Summary of the Invention

[0004] In order to solve the above technical problems, this application provides a coating agent for expandable polystyrene particles, a preparation method thereof, and an application thereof.

[0005] In a first aspect, this application provides a coating agent for expandable polystyrene particles. The raw materials used include the following components in parts by weight: 20-30 parts of a film-forming agent; 30-40 parts of an emulsifier; 30-35 parts of a lubricant; 10-15 parts of an anti-permeation material; the emulsifier includes decaglycerol decastearate and glycerol monostearate with a weight ratio of 1:(1-2), and the anti-permeation material is prepared from a functional monomer and activated graphene. The functional monomer includes 2-acrylamido-2-methylpropanesulfonic acid and / or sodium p-styrenesulfonate.

[0006] By adopting the above technical solutions, the present application first forms a protective film on the surface of the particles by using a film-forming agent, effectively reducing the direct contact between the particles, thereby reducing friction and adhesion phenomena, improving the dispersibility of the particles. It also uses decaglycerol decastearate and glycerol monostearate with a certain weight ratio as emulsifiers, which can further enhance the uniformity and stability of the coating, ensure a more firm attachment of the coating on the particle surface, and avoid the shedding of the coating caused by particle movement. The introduction of the lubricant significantly reduces the friction coefficient between the particles, reduces the mechanical damage of the particles during transportation and storage, and improves the fluidity of the particles. Most importantly, the present application adds an anti-permeation material, which is prepared by the compounding of a functional monomer and activated graphene, can effectively prevent the penetration of external impurities, protect the internal structure of the particles from being damaged, extend the service life of the particles, and at the same time can be embedded in the concave parts of the particle surface, further reducing the friction degree between the particles, and can also enhance the overall strength and durability of the coating, making the coating more anti-adhesion.

[0007] Generally speaking, the coating agent of the present application can ensure that the friction and adhesion phenomena between the particles are well improved, reducing the possibility of coating damage during the friction between different particles. Experimental data shows that the adhesion degree of EPS particles added with the coating agent is only level 2 or below, slightly adhered, some particles are in contact or even completely independent, without adhesion. And because the particles are well protected, the tensile strength of the final foaming template is also improved, with at least a 6.97% increase in the tensile strength after foaming compared to the particles without the coating agent.

[0008] Preferably, the functional monomer includes 2-acrylamido-2-methylpropanesulfonic acid and sodium p-styrenesulfonate with a weight ratio of 1:(1.5 - 2).

[0009] By adopting the above technical solutions, the functional monomer in the anti-permeation material of the present application is composed of 2-acrylamido-2-methylpropanesulfonic acid and sodium p-styrenesulfonate with a weight ratio of 1:(1.5 - 2). This ratio can significantly improve the stability and functionality of the anti-permeation material, specifically manifested in enhancing the protection ability of the coating agent on the surface of expandable polystyrene particles, effectively preventing the adhesion phenomenon between particles; at the same time, the optimized functional monomer ratio can also improve the anti-permeation performance of the coating, reducing the influence of moisture or other external substances on the particles, thereby further improving the apparent integrity and service life of the foaming material.

[0010] Preferably, the preparation method of the anti-permeation material comprises the following steps: dispersing activated graphene, functional monomer and potassium persulfate in water, reacting at pH = 8.5 - 9.5 and a temperature of 85 - 95 °C for 4 - 6 h, cooling, filtering to obtain a solid, washing, drying, and grinding to 300 - 325 mesh to obtain the anti-permeation material, and the weight ratio of activated graphene to functional monomer is (180 - 190):1.

[0011] By adopting the above technical solution, the preparation method of the anti-permeation material of the present application can effectively improve the performance of the anti-permeation material by precisely controlling the ratio of activated graphene to functional monomer and the reaction conditions. The combination of activated graphene and functional monomer at a specific ratio enhances the anti-adhesion ability of the coating agent. At the same time, the introduction of 2-acrylamide-2-methylpropanesulfonic acid and sodium styrenesulfonate in the functional monomer further improves the lubricating effect of the coating; by reacting at pH = 8.5 - 9.5 and a temperature of 85 - 95 °C for 4 - 6 h, the uniform dispersion and sufficient cross-linking of the material are ensured, thereby improving the stability and durability of the coating; finally, after grinding to 300 - 325 mesh, the anti-permeation material has finer particle size, which is beneficial to its dispersion and adhesion in the coating agent.

[0012] Preferably, the raw materials used include the following components in parts by weight: 28 parts of film-forming agent; 37 parts of emulsifier; 33 parts of lubricant; 12 parts of anti-permeation material.

[0013] By adopting the above technical solution, the present application further optimizes the component ratios of the coating agent for expandable polystyrene particles, can form a more uniform and stable protective film on the particle surface, improve the adhesion and durability of the coating, effectively improve the dispersion performance of the coating agent, reduce the adhesion between particles, enhance the lubricating effect between particles, reduce friction, avoid damage to the particle surface, significantly improve the anti-permeation performance of the coating, and prevent external substances from eroding the particles. This preferred ratio can comprehensively improve the protection performance of expandable polystyrene particles and ensure their dispersion and apparent integrity during transportation and storage.

[0014] Preferably, the film-forming agent comprises polyvinyl alcohol and citric acid in a weight ratio of 5:(2 - 8).

[0015] By adopting the above technical solution, the present application uses polyvinyl alcohol and citric acid compounded in a specific weight ratio as the film-forming agent, which can form a uniform and dense protective film, effectively improve the overall adhesion and durability of the coating. Polyvinyl alcohol provides good film-forming performance, while citric acid enhances the flexibility and weather resistance of the coating. The two work together to ensure the stable adhesion of the coating on the surface of expandable polystyrene particles, reduce the friction and adhesion between particles, and thus improve the apparent integrity and service life of the foamed material.

[0016] Preferably, the weight ratio of the polyvinyl alcohol to the citric acid is 5:5.

[0017] By adopting the above technical solution, the present application combines polyvinyl alcohol and citric acid in a weight ratio of 5:4, which can further optimize the performance of the film-forming agent. The film-forming agent under this ratio can not only form a uniform and dense protective film on the surface of expandable polystyrene particles, but also effectively enhance the flexibility and adhesion of the coating, reduce the coating damage caused by the friction between particles, thereby better maintaining the dispersed state of the particles and preventing the occurrence of adhesion phenomena.

[0018] Preferably, the lubricant is prepared by the following method: melt ethylene bisstearamide under the protection of an inert gas, then add glacial acetic acid, keep the temperature at 190 - 200 °C for heat preservation reaction for 4 - 5 h, cool, filter to obtain a solid, wash, dry, and grind to 300 - 325 mesh to obtain the lubricant, and the weight ratio of ethylene bisstearamide to glacial acetic acid is 1:(0.18 - 0.22).

[0019] By adopting the above technical solution, the present application reacts ethylene bisstearamide and glacial acetic acid under specific conditions, which can significantly improve the stability and dispersibility of the lubricant. Specifically, reacting under the protection of an inert gas can effectively avoid the occurrence of side reactions and ensure the product purity; while the weight ratio of ethylene bisstearamide to glacial acetic acid being 1:(0.18 - 0.22) further optimizes the proportion of the reactants, making the generated lubricant have more excellent lubricating properties. When this lubricant is applied to the coating agent for expandable polystyrene particles, it can enhance the overall stability of the coating agent, reduce the adhesion phenomenon between particles, thereby improving the apparent integrity and service life of the final foamed material.

[0020] Preferably, the weight ratio of the ethylene bisstearamide to the glacial acetic acid is 1:0.2.

[0021] By adopting the above technical solution, the present application optimizes the weight ratio of ethylene bisstearamide to glacial acetic acid to 1:0.2, making the reaction in the preparation process of the lubricant more complete, and the generated lubricant has more excellent stability and dispersibility. This adjustment of the ratio further improves the effect of the lubricant in the coating agent, enhances the protection ability of the coating agent on the surface of expandable polystyrene particles, effectively reduces the adhesion phenomenon between particles, and at the same time improves the uniformity and friction resistance of the coating.

[0022] In the second aspect, the present application provides a preparation method of the above coating agent for expandable polystyrene particles, including the following steps: blend all raw materials and grind them under the condition of 20 - 25 °C until the particle size is 300 - 325 mesh to obtain the coating agent for expandable polystyrene particles.

[0023] By adopting the above technical solution, the present application first blends all raw materials at a relatively low temperature, ensuring the uniform dispersion of each component, improving the overall performance stability of the coating agent, and providing a reliable guarantee for subsequent applications.

[0024] In a third aspect, the present application provides an application of the coating agent for expandable polystyrene particles as described above. The coating agent for expandable polystyrene particles is mixed with expandable polystyrene particles according to a weight ratio of (0.1 - 0.2):100, and then injection-molded to obtain expandable polystyrene particles with a protective coating on the surface.

[0025] By adopting the above technical solution, the coating agent of the present application can form a protective film on the surface of EPS particles, significantly improving the dispersibility and anti-sticking performance of the particles, reducing the frictional damage between the particles. Decaglycerol decastearate and glycerol monostearate further enhance the uniformity and stability of the coating, ensuring that the coating firmly adheres to the particle surface. The addition of the lubricant greatly reduces the frictional force between the particles, effectively preventing the particles from sticking to each other during transportation and storage. The anti-permeation material not only improves the anti-permeation performance of the coating, but also optimizes the apparent integrity of the EPS particles, thereby improving the appearance quality of the final foamed material. Good synergistic effects are generated among the various components of the present application, and the ratio ranges of the various components are optimized, ensuring that the comprehensive performance of the coating agent reaches the best state in practical applications, effectively improving the adhesion and caking problems that occur during the foaming process of EPS particles, and greatly reducing the possibility of partial damage to the coating during the friction between different EPS particles.

[0026] In summary, the present application has the following beneficial technical effects: 1. By adding an anti-permeation material prepared from a functional monomer and activated graphene, the coating agent of the present application can effectively prevent the penetration of external impurities, protect the internal structure of the particles from being damaged, extend the service life of the particles, and at the same time can be embedded in the concave parts of the particle surface, further reducing the friction degree between the particles, and also improving the overall strength and durability of the coating, making the coating more anti-sticking; a specific ratio of emulsifier combination, including decaglycerol decastearate and glycerol monostearate, is also adopted to improve the dispersibility and stability of the coating agent.

[0027] 2. The preparation method of the present application blends all raw materials at a relatively low temperature, ensuring the uniform dispersion of each component, improving the overall performance stability of the coating agent, and providing a reliable guarantee for subsequent applications.

[0028] 3. The application of the coating agent of the present application can effectively improve the adhesion and caking problems that occur during the foaming process of EPS particles, and greatly reduce the possibility of partial damage to the coating during the friction between different EPS particles. Detailed implementation mode

[0029] Material source Unless otherwise specified, the raw materials used in this application are all commercially available products, specifically: Graphene was purchased from Hebei Ruihuang Metal Materials Co., Ltd.; 2 - acrylamide - 2 - methylpropanesulfonic acid, with a CAS number of 15214 - 89 - 8; Sodium p - styrenesulfonate, with a CAS number of 2695 - 37 - 6; Ethylene bisstearamide, with a CAS number of 110 - 30 - 5; Decaglycerol decastearate, with a CAS number of 39529 - 26 - 5; Glycerol monostearate, with a CAS number of 123 - 94 - 4; Polyvinyl alcohol, with a CAS number of 9002 - 89 - 5; Citric acid, with a CAS number of 77 - 92 - 9.

[0030] The following further elaborates on this application in combination with examples and comparative examples.

[0031] Preparation Example 1.1 A preparation method of an anti - permeation material, comprising the following steps: Disperse 200 g of graphene, 150 g of potassium permanganate, and 300 mL of 95 wt% sulfuric acid in 10 L of deionized water, react at a temperature of 85 °C for 3 h, then slowly add 2.5 L of 30 wt% hydrogen peroxide dropwise. When the color of the substances in the system no longer changes, centrifuge and precipitate. Wash the precipitate with 5 wt% sodium hydroxide solution until the upper clear liquid is transparent to obtain activated graphene. Disperse the activated graphene in deionized water and control the concentration of activated graphene to be 5 mg / mL, adjust the pH value to 8.5, and perform ultrasonic treatment at a power of 800 W for 30 min for standby; Mix 2000 mL of the above - mentioned activated graphene aqueous solution, 1.8 kg of functional monomer (2 - acrylamide - 2 - methylpropanesulfonic acid), and 2.7 g of potassium persulfate, react under the conditions of pH = 9.5 and a temperature of 85 °C for 6 h, cool, filter to obtain a solid, wash with methanol, and then dry at a temperature of 105 °C and grind to 300 meshes to obtain the anti - permeation material.

[0032] Preparation Example 1.2 A preparation method of an anti - permeation material, comprising the following steps: Disperse 200 g of graphene, 150 g of potassium permanganate, and 300 mL of 95 wt% sulfuric acid in 10 L of deionized water, react at a temperature of 85 °C for 3 h, then slowly add dropwise 2.5 L of 30 wt% hydrogen peroxide. When the color of the substances in the system no longer changes, centrifuge and precipitate, wash the precipitate with 5 wt% sodium hydroxide solution until the upper clear liquid is transparent to obtain activated graphene. Disperse the activated graphene in deionized water and control the concentration of the activated graphene to be 5 mg / mL, adjust the pH value to 8.5, and ultrasonically treat at a power of 800 W for 30 min for standby; mix 2000 mL of the above-mentioned activated graphene aqueous solution, 1.9 kg of functional monomer (sodium p-styrenesulfonate), and 2.7 g of potassium persulfate, react under the conditions of pH = 8.5 and a temperature of 95 °C for 4 h, cool, filter to obtain a solid, wash with methanol, and then dry at a temperature of 105 °C and grind to 325 mesh to obtain the anti-permeation material.

[0033] Preparation Example 2.1 The preparation method of the anti-permeation material is different from that of Preparation Example 1.1 in that 1.8 kg of 2-acrylamido-2-methylpropanesulfonic acid is replaced with 0.45 kg of 2-acrylamido-2-methylpropanesulfonic acid and 1.35 kg of sodium p-styrenesulfonate, and the rest are the same as those in Preparation Example 1.1.

[0034] Preparation Example 2.2 The preparation method of the anti-permeation material is different from that of Preparation Example 1.1 in that 1.8 kg of 2-acrylamido-2-methylpropanesulfonic acid is replaced with 0.6 kg of 2-acrylamido-2-methylpropanesulfonic acid and 1.2 kg of sodium p-styrenesulfonate, and the rest are the same as those in Preparation Example 1.1.

[0035] Preparation Example 2.3 The preparation method of the anti-permeation material is different from that of Preparation Example 1.1 in that 1.8 kg of 2-acrylamido-2-methylpropanesulfonic acid is replaced with 0.72 kg of 2-acrylamido-2-methylpropanesulfonic acid and 1.08 kg of sodium p-styrenesulfonate, and the rest are the same as those in Preparation Example 1.1.

[0036] Preparation Example 2.4 The preparation method of the anti-permeation material is different from that of Preparation Example 1.1 in that 1.8 kg of 2-acrylamido-2-methylpropanesulfonic acid is replaced with 0.9 kg of 2-acrylamido-2-methylpropanesulfonic acid and 0.9 kg of sodium p-styrenesulfonate, and the rest are the same as those in Preparation Example 1.1.

[0037] Preparation Example 3.1 The preparation method of the lubricant includes the following steps: Under the condition of nitrogen protection, 1 kg of ethylene bisstearamide was heated to melt, then 180 g of glacial acetic acid was added, and the reaction was carried out under insulation at 200 °C for 4 h. After cooling, the solid was filtered, washed, dried, and ground to 300 mesh to obtain the lubricant.

[0038] Preparation Example 3.2 A method for preparing a lubricant, comprising the following steps: Under the condition of nitrogen protection, 1 kg of ethylene bisstearamide was heated to melt, then 220 g of glacial acetic acid was added, and the reaction was carried out under insulation at 190 °C for 5 h. After cooling, the solid was filtered, washed, dried, and ground to 325 mesh to obtain the lubricant.

[0039] Preparation Example 3.3 The method for preparing a lubricant is different from Preparation Example 3.1 in that the amount of glacial acetic acid used is 190 g, and the rest are the same as Preparation Example 1.1.

[0040] Preparation Example 3.4 The method for preparing a lubricant is different from Preparation Example 3.1 in that the amount of glacial acetic acid used is 200 g, and the rest are the same as Preparation Example 1.1.

[0041] Preparation Example 3.5 The method for preparing a lubricant is different from Preparation Example 3.1 in that the amount of glacial acetic acid used is 210 g, and the rest are the same as Preparation Example 1.1.

[0042] Example 1.1 A method for preparing a coating agent for expandable polystyrene particles, comprising the following steps: 300 g of a film-forming agent (polyvinyl alcohol), 300 g of an emulsifier (100 g of decaglycerol distearate and 200 g of glycerol monostearate), 350 g of a lubricant (ethylene bisstearamide), and 100 g of the anti-permeation material prepared in Preparation Example 1.1 were blended and ground under the condition of 25 °C until the particle size reached 325 mesh to obtain the coating agent for expandable polystyrene particles.

[0043] Example 1.2 A method for preparing a coating agent for expandable polystyrene particles, comprising the following steps: 200 g of a film-forming agent (polyvinyl alcohol), 400 g of an emulsifier (200 g of decaglycerol distearate and 200 g of glycerol monostearate), 300 g of a lubricant (ethylene bisstearamide), and 150 g of the anti-permeation material prepared in Preparation Example 1.2 were blended and ground under the condition of 20 °C until the particle size reached 300 mesh to obtain the coating agent for expandable polystyrene particles.

[0044] Example 1.3 A preparation method of a coating agent for expandable polystyrene particles, comprising the following steps: Blend 280 g of a film-forming agent (polyvinyl alcohol), 370 g of an emulsifier (150 g of decaglycerol distearate and 220 g of glycerol monostearate), 330 g of a lubricant (ethylene bisstearamide), and 120 g of the anti-permeation material prepared in Preparation Example 1.1, and grind at 22 °C until the particle size reaches 325 mesh to obtain a coating agent for expandable polystyrene particles.

[0045] Examples 2.1 - 2.4 A preparation method of a coating agent for expandable polystyrene particles, which is different from Example 1.3 in that the anti-permeation material prepared in Preparation Example 1.1 is respectively replaced with the anti-permeation materials prepared in Preparation Examples 2.1 - 2.4, and the rest are the same as Example 1.3.

[0046] Example 3.1 A preparation method of a coating agent for expandable polystyrene particles, which is different from Example 1.3 in that polyvinyl alcohol is replaced with 200 g of polyvinyl alcohol and 80 g of citric acid, and the rest are the same as Example 1.3.

[0047] Example 3.2 A preparation method of a coating agent for expandable polystyrene particles, which is different from Example 1.3 in that polyvinyl alcohol is replaced with 107.8 g of polyvinyl alcohol and 172.2 g of citric acid, and the rest are the same as Example 1.3.

[0048] Example 3.3 A preparation method of a coating agent for expandable polystyrene particles, which is different from Example 1.3 in that polyvinyl alcohol is replaced with 140 g of polyvinyl alcohol and 140 g of citric acid, and the rest are the same as Example 1.3.

[0049] Examples 4.1 - 4.5 A preparation method of a coating agent for expandable polystyrene particles, which is different from Example 1.3 in that ethylene bisstearamide is respectively replaced with the lubricants prepared in Preparation Examples 3.1 - 3.5, and the rest are the same as Example 1.3.

[0050] Comparative Example 1 It is different from Example 1.3 in that the anti-permeation material prepared in Preparation Example 1.1 is removed, and the rest are the same as Example 1.3.

[0051] Comparative Example 2 It is different from Example 1.3 in that decaglycerol distearate is removed, and the amount of glycerol monostearate is changed to 370 g, and the rest are the same as Example 1.3.

[0052] Comparative Example 3 The difference from Example 1.3 is that glycerol monostearate is removed, and the dosage of decaglycerol decastearate is changed to 370 g, and the rest is the same as Example 1.3.

[0053] Performance detection The coating agents prepared in the examples and comparative examples were blended with EPS particles (self-made, the tensile strength after making plates was 24.4 MPa), the blending weight ratio was controlled to be 0.15:100, the discharging time was 80 min, the mixing time was 100 min, and injection molding was carried out at a temperature of 200 °C to obtain expandable polystyrene particles with a protective coating on the surface, and their adhesion degree was judged. The results are shown in Table 1; subsequently, the expandable polystyrene particles with a protective coating on the surface were foamed, and then the tensile strength (MPa) of the sample was measured according to the records in GB 9641-1988 "Test Method for Tensile Properties of Rigid Foamed Plastics", the measurement temperature was 25 °C, and the moving speed of the fixture was 5 ± 1 mm / min. The results are shown in Table 1; Note: 1. The adhesion degree is classified as: Grade 1, the EPS particles are completely independent and there is no adhesion; Grade 2, the EPS particles are slightly adhered and there is contact between some particles; Grade 3, the EPS particles are adhered and there is obvious contact between multiple particles, but they can be separated; Grade 4, the EPS particles are severely adhered and even form large blocks and cannot be separated; 2. The blending weight ratio between the coating agent of the present application and the EPS particles is only taken as an example of 0.15:100.

[0054] Table 1 Performance detection table Data analysis: As can be seen from Table 1, the adhesion degree of the particles in Examples 1.1-1.3 is only Grade 2, and the tensile strength of the sample is 26.1-26.8 MPa. Compared with the tensile strength of the particles after foaming without adding the coating agent, it has increased by at least 6.97%, which proves that the coating agent of the present application can effectively prevent the penetration of external impurities, protect the internal structure of the particles from being damaged, extend the service life of the particles, and at the same time can be embedded in the concave parts on the surface of the particles, further reducing the friction degree between the particles, forming a protective film on the surface of the particles, effectively reducing the direct contact between the particles, thereby reducing the friction and adhesion phenomena, improving the dispersibility of the particles, reducing the mechanical damage of the particles during transportation and storage, and at the same time improving the fluidity of the particles.

[0055] In Examples 2.1 - 2.4, the present application changed the proportion of functional monomers in the preparation of the anti - permeation material. The results showed that the degree of particle adhesion in Examples 2.2 - 2.3 was lower than that of other examples, and the tensile strength of the sample was greater. This proved that by optimizing the ratio of functional monomers, the present application enhanced the protective ability of the coating agent on the surface of expandable polystyrene particles, effectively preventing the adhesion between particles, improving the anti - permeation performance of the coating, reducing the influence of moisture or other external substances on the particles, and thus further improving the apparent integrity and service life of the foamed material.

[0056] In Examples 3.1 - 3.3, the present application changed the components and ratio of the film - forming agent. The results showed that the degree of particle adhesion decreased and the tensile strength of the sample increased. This proved that by compounding polyvinyl alcohol and citric acid in a specific weight ratio as the film - forming agent, a uniform and dense protective film could be formed, effectively improving the overall adhesion and durability of the coating. Polyvinyl alcohol provided good film - forming performance, while citric acid enhanced the flexibility and weather resistance of the coating. The two worked together to ensure the stable adhesion of the coating on the surface of expandable polystyrene particles, reducing the friction and adhesion between particles, and thus improving the apparent integrity and service life of the foamed material. Among them, the data of Example 3.2 was the best, proving that the film - forming agent with a weight ratio of polyvinyl alcohol to citric acid of 5:4 could not only form a uniform and dense protective film on the surface of expandable polystyrene particles, but also effectively enhance the flexibility and adhesion of the coating, reducing the coating damage caused by friction between particles, and thus better maintaining the dispersed state of the particles and preventing the occurrence of adhesion phenomena.

[0057] In Examples 4.1 - 4.5, the present application changed the composition of the emulsifier. The results showed that the degree of particle adhesion decreased and the tensile strength of the sample increased. This proved that by reacting ethylene bisstearamide with glacial acetic acid under specific conditions, the stability and dispersibility of the lubricant could be significantly improved, enhancing the overall stability of the coating agent, reducing the adhesion between particles, and thus improving the apparent integrity and service life of the final foamed material.

[0058] In Examples 4.1 - 4.5, the degree of particle adhesion in Example 4.4 was the lowest and the tensile strength of the sample was the highest. This proved that by optimizing the weight ratio of ethylene bisstearamide to glacial acetic acid to 1:0.2, the reaction in the preparation process of the lubricant was more complete, and the generated lubricant had more excellent stability and dispersibility. The adjustment of this ratio further improved the effect of the lubricant in the coating agent, enhanced the protective ability of the coating agent on the surface of expandable polystyrene particles, effectively reduced the adhesion between particles, and at the same time improved the uniformity and friction resistance of the coating.

[0059] The degree of particle adhesion in Comparative Example 1 increased, and the tensile strength of the sample decreased, proving that the anti-permeation material of the present application can effectively prevent the penetration of external impurities, protect the internal structure of the particles from damage, extend the service life of the particles, and at the same time can be embedded in the concave parts of the particle surface, further reducing the friction between particles, and can also improve the overall strength and durability of the coating, making the coating more anti-adhesion performance.

[0060] The degree of particle adhesion in Comparative Examples 2-3 increased, and the tensile strength of the sample decreased, proving that the present application uses decaglycerol decastearate and glycerol monostearate with a certain weight ratio as emulsifiers, which can further enhance the uniformity and stability of the coating, ensure the more firm adhesion of the coating on the particle surface, and avoid the peeling off of the coating caused by particle movement.

[0061] The embodiments of this specific implementation manner are all preferred embodiments of the present application, and do not limit the protection scope of the present application accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A coating agent for expandable polystyrene particles, characterized in that, The raw materials used include the following components in parts by weight: film-forming agent 20-30 parts; emulsifier 30-40 parts; lubricant 30-35 parts; anti-permeation material 10-15 parts; the emulsifier includes decaglycerol decastearate and glycerol monostearate with a weight ratio of 1:(1-2), and the anti-permeation material is prepared from a functional monomer and activated graphene, and the functional monomer includes 2-acrylamido-2-methylpropanesulfonic acid and / or sodium p-styrenesulfonate.

2. The coating agent for expandable polystyrene particles according to claim 1, characterized in that, The functional monomer includes 2-acrylamido-2-methylpropanesulfonic acid and sodium p-styrenesulfonate with a weight ratio of 1:(1.5-2).

3. The coating agent for expandable polystyrene particles according to claim 1, wherein, The preparation method of the anti-permeation material includes the following steps: Disperse activated graphene, functional monomer and potassium persulfate in water, react at pH = 8.5-9.5 and a temperature of 85-95 °C for 4-6 h, cool, filter to obtain a solid, wash, dry, and grind to 300-325 mesh to obtain the anti-permeation material, and the weight ratio of activated graphene to functional monomer is (180-190):

1.

4. A coating agent for expandable polystyrene particles according to claim 1, characterized in that, The raw materials used include the following components in parts by weight: film-forming agent 28 parts; emulsifier 37 parts; lubricant 33 parts; Anti-permeation material 12 parts.

5. The coating agent for expandable polystyrene particles according to claim 1, wherein The film-forming agent includes polyvinyl alcohol and citric acid with a weight ratio of 5:(2-8).

6. The coating agent for expandable polystyrene particles according to claim 5, characterized in that, The weight ratio of polyvinyl alcohol to citric acid is 5:

5.

7. A coating agent for expandable polystyrene particles according to claim 1, characterized in that, The lubricant is prepared by the following method: Melt ethylene bisstearamide under the protection of an inert gas, then add glacial acetic acid, keep the temperature at 190-200 °C and react for 4-5 h, cool, filter to obtain a solid, wash, dry, and grind to 300-325 mesh to obtain the lubricant, and the weight ratio of ethylene bisstearamide to glacial acetic acid is 1:(0.18-0.22).

8. A coating agent for expandable polystyrene particles according to claim 7, characterized in that, The weight ratio of ethylene bisstearamide to glacial acetic acid is 1:0.

2.

9. A method for preparing a coating agent for expandable polystyrene particles according to any one of claims 1-8, characterized in that, Includes the following steps: Blend all the raw materials and grind them at 20-25 °C until the particle size is 300-325 mesh to obtain a coating agent for expandable polystyrene particles.

10. Use of a coating agent for expandable polystyrene particles according to any one of claims 1-8, characterized in that, Mix the coating agent for expandable polystyrene particles and expandable polystyrene particles according to a weight ratio of (0.1-0.2):100, and carry out injection molding to obtain expandable polystyrene particles with a protective coating on the surface.

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