A coating agent for expandable polystyrene particles, a method for preparing the same, and use thereof

Abstract

The application relates to the field of polymer material processing, and particularly discloses a coating agent for expandable polystyrene particles, a preparation method and application thereof. The coating agent for expandable polystyrene particles is prepared from 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; and 10-15 parts of an anti-permeation material. The emulsifier comprises decaglycerin decastearate and glycerin monostearate in a weight ratio of 1: (1-2). The anti-permeation material is prepared from a functional monomer and activated graphene. The functional monomer comprises 2-acrylamide-2-methylpropanesulfonic acid and / or sodium p-styrenesulfonate. The product can be used for apparent protection of expandable polystyrene particles, can effectively improve the problems of adhesion and caking of EPS particles in the foaming process, and greatly reduces the possibility of damage to the coating part in the process of friction between different EPS particles.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polymer material processing, and in particular to a coating agent for expandable polystyrene particles, a preparation method and application thereof. BACKGROUND

[0002] Expandable polystyrene (EPS) particles are a kind of polystyrene products added with a foaming agent, and the appearance is colorless transparent bead-shaped particles. EPS particles are widely used in cushion packaging materials, building insulation boards (such as EPS insulation boards), etc., and its light weight feature can reduce transportation costs and improve insulation performance. Since EPS particles are prone to mutual adhesion and caking during foaming, this will cause appearance defects on the surface of the final foaming material, affecting the appearance and service life. Therefore, researchers have proposed coating protection on the surface of EPS particles to ensure the dispersion of EPS particles during storage and transportation, and to optimize the apparent integrity of the final foaming material.

[0003] The current coating protective agent is composed of a film-forming agent, a lubricant and an emulsifier, but as people find in actual use that the surface of EPS particles itself has unevenness problems, therefore, the lubricating effect of the existing lubricant is also difficult to ensure that the friction and adhesion between particles are well improved, and in the process of friction between different particles, the coating part may still be damaged, therefore, the lubricating effect and anti-adhesion effect of the coating agent for expandable polystyrene particles have a lot of room for improvement. SUMMARY

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

[0005] In a first aspect, the present application provides a coating agent for expandable polystyrene particles, the raw materials used including the following components 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 a permeation-resistant material; the emulsifier includes decaglycerol decastearate and glycerol monostearate in a weight ratio of 1:(1-2), the permeation-resistant material is prepared from a functional monomer and activated graphene, and the functional monomer includes 2-acrylamide-2-methylpropane sulfonic acid and / or sodium p-styrene sulfonate.

[0006] By adopting the technical scheme, firstly, the film forming agent is used to form a protective film on the surface of the particles, effectively reducing the direct contact between the particles, thereby reducing the friction and adhesion phenomenon, and improving the dispersibility of the particles. Secondly, a certain weight ratio of decaglycerol decastearate and glycerol monostearate is used as an emulsifier, which can further enhance the uniformity and stability of the coating, ensure the adhesion of the coating on the surface of the particles, avoid the peeling of the coating caused by the movement of the particles, and reduce the friction coefficient between the particles. Thirdly, the introduction of the lubricant greatly reduces the mechanical damage of the particles during transportation and storage, and improves the flowability of the particles. Most importantly, the anti-permeation material is added, which is prepared by compounding the functional monomer with activated graphene, can effectively prevent the penetration of external impurities, protect the internal structure of the particles from being damaged, prolong the service life of the particles, and can also embed into the recesses on the surface of the particles, further reduce the friction between the particles, and improve the overall strength and durability of the coating, making the coating more resistant to adhesion.

[0007] Overall, the coating agent of the present application can effectively improve the friction and adhesion between particles, reduce the possibility of coating damage during friction between different particles, and experimental data shows that the adhesion degree of EPS particles with the coating agent is only 2 or below, with slight adhesion, some particles are in contact, and even the particles are completely independent without adhesion. Moreover, due to the good protection of the particles, the tensile strength of the final foaming sample is also improved, which is at least 6.97% higher than that of the particles without the coating agent.

[0008] Preferably, the functional monomer comprises 2-acrylamide-2-methylpropane sulfonic acid and sodium p-styrenesulfonate in a weight ratio of 1:(1.5-2).

[0009] By adopting the technical scheme, the functional monomer in the anti-permeation material of the present application is composed of 2-acrylamide-2-methylpropane sulfonic acid and sodium p-styrenesulfonate in a weight ratio of 1:(1.5-2), which can significantly improve the stability and functionality of the anti-permeation material. Specifically, it can enhance the protection ability of the coating agent on the surface of the expandable polystyrene particles, effectively prevent the adhesion phenomenon between the particles, and improve the anti-permeation performance of the coating, reduce the influence of water or other external substances on the particles, and further improve 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 for 4-6h under the condition of pH=8.5-9.5 and temperature of 85-95℃, cooling, filtering to obtain solid, washing, drying, grinding to 300-325 mesh, to obtain the anti-permeation material, and the weight ratio of activated graphene and functional monomer is (180-190):1.

[0011] By adopting the technical scheme, the preparation method of the anti-permeation material can effectively improve the performance of the anti-permeation material by accurately controlling the ratio of activated graphene and functional monomer and the reaction condition, the activated graphene and the functional monomer are combined at a specific ratio to enhance the anti-blocking ability of the coating agent, and the introduction of 2-acrylamide-2-methylpropanesulfonic acid and sodium p-styrenesulfonate in the functional monomer further improves the lubricating effect of the coating; by reacting for 4-6h under the condition of pH=8.5-9.5 and temperature of 85-95℃, the uniform dispersion and sufficient crosslinking of the material are ensured, thereby improving the stability and durability of the coating; and finally, grinding to 300-325 mesh makes the anti-permeation material have finer particle size, which is beneficial to the dispersibility and adhesion of the anti-permeation material in the coating agent.

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

[0013] By adopting the technical scheme, the proportions of the components of the expandable polystyrene particle coating agent are further optimized, a more uniform and stable protective film can be formed on the particle surface, the adhesion and durability of the coating are improved, the dispersibility of the coating agent is effectively improved, the adhesion phenomenon between the particles is reduced, the lubricating effect between the particles is enhanced, the friction is reduced, the surface of the particles is prevented from being damaged, the anti-permeation performance of the coating is significantly improved, and the erosion of external substances on the particles is prevented. The preferred proportions can comprehensively improve the protection performance of the expandable polystyrene particles, and ensure the dispersibility and apparent integrity of the particles 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 technical scheme, the polyvinyl alcohol and citric acid are compounded as the film-forming agent according to a specific weight ratio, a uniform and dense protective film can be formed, the overall adhesion and durability of the coating are effectively improved, the polyvinyl alcohol provides good film-forming performance, and the citric acid enhances the flexibility and weather resistance of the coating, the two components synergistically ensure the stable adhesion of the coating on the surface of the expandable polystyrene particles, reduce the friction and adhesion phenomenon between the particles, and thereby improve the apparent integrity and service life of the foamed material.

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

[0017] By adopting the technical scheme, the polyvinyl alcohol and the citric acid are matched in a weight ratio of 5:4, so that the performance of the film forming agent can be further optimized. The film forming agent in this ratio can not only form a uniform and dense protective film on the surface of the expandable polystyrene particles, but also effectively enhance the flexibility and adhesion of the coating, reduce the damage of the coating caused by friction between the particles, and better maintain the dispersion state of the particles and prevent the occurrence of the adhesion phenomenon.

[0018] Preferably, the lubricant is prepared by the following method: melting ethylene bis-stearamide under the condition of inert gas protection, then adding glacial acetic acid, and reacting at a temperature of 190-200°C for 4-5h, cooling, filtering to obtain a solid, washing, drying, and grinding to 300-325 mesh to obtain the lubricant, and the weight ratio of ethylene bis-stearamide to glacial acetic acid is 1:(0.18-0.22).

[0019] By adopting the technical scheme, the ethylene bis-stearamide and the glacial acetic acid are reacted under specific conditions, so that the stability and dispersibility of the lubricant can be significantly improved. Specifically, the reaction under the condition of inert gas protection can effectively avoid the occurrence of side reactions and ensure the purity of the product; and the weight ratio of ethylene bis-stearamide to glacial acetic acid is 1:(0.18-0.22), which further optimizes the proportion of the reactants, so that the generated lubricant has more excellent lubricating performance. The lubricant applied in the coating agent for expandable polystyrene particles can enhance the overall stability of the coating agent, reduce the adhesion phenomenon between the particles, and thus improve the apparent integrity and service life of the final foamed material.

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

[0021] By adopting the technical scheme, the weight ratio of the ethylene bis-stearamide to the glacial acetic acid is optimized to 1:0.2, so that the reaction in the preparation process of the lubricant is more sufficient, and the generated lubricant has more excellent stability and dispersibility. The adjustment of this ratio further improves the effect of the lubricant in the coating agent, enhances the protection ability of the coating agent to the surface of the expandable polystyrene particles, effectively reduces the adhesion phenomenon between the particles, and improves the uniformity and friction resistance of the coating.

[0022] In the second aspect, the application provides a preparation method of the above-mentioned coating agent for expandable polystyrene particles, which comprises the following steps: blending all the raw materials, and grinding at a temperature 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 technical scheme, the present application first blends all raw materials at a lower temperature, ensures uniform dispersion of each component, improves overall performance stability of the coating agent, and provides reliable guarantee for subsequent application.

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

[0025] By adopting the technical scheme, the coating agent of the present application can form a protective film on the surface of the EPS particles, significantly improve the dispersibility and anti-blocking performance of the particles, reduce the friction damage between the particles, and further enhance the uniformity and stability of the coating by using decaglycerol decastearate and glycerol monostearate, so as to ensure that the coating is firmly attached to the surface of the particles. The addition of the lubricant greatly reduces the friction between the particles, effectively prevents the particles from adhering to each other during transportation and storage, and 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 foaming material. The various components of the present application have a good coordination effect, and the component ratio range is optimized to ensure that the comprehensive performance of the coating agent in actual application reaches the best state, which can effectively improve the blocking and caking problems of the EPS particles during the foaming process, and greatly reduce the possibility of damage to the coating part during the friction process of different EPS particles.

[0026] In summary, the present application has the following beneficial technical effects:

[0027] 1. The coating agent of the present application can effectively prevent the penetration of external impurities by adding an anti-permeation material made of a functional monomer and activated graphene, protect the internal structure of the particles from being damaged, prolong the service life of the particles, embed into the recesses on the surface of the particles, further reduce the friction between the particles, and improve the overall strength and durability of the coating, making the coating more resistant to blocking. The emulsifier combination with a specific ratio, including decaglycerol decastearate and glycerol monostearate, improves the dispersibility and stability of the coating agent.

[0028] 2. The preparation method of the present application blends all raw materials at a lower temperature, ensures uniform dispersion of each component, improves overall performance stability of the coating agent, and provides reliable guarantee for subsequent application.

[0029] 3. The application of the coating agent can effectively improve the adhesion and caking problems of EPS particles in the foaming process, greatly reducing the possibility of damage to the coating part during the friction process of different EPS particles. DETAILED DESCRIPTION

[0030] Material sources

[0031] The raw materials used in the application are commercially available products, specifically:

[0032] Graphene was purchased from Hebei Ruihuang Metal Material Co., Ltd.;

[0033] 2-acrylamide-2-methylpropane sulfonic acid, CAS No. 15214-89-8;

[0034] Sodium p-styrenesulfonate, CAS No. 2695-37-6;

[0035] Ethylene bis-stearamide, CAS No. 110-30-5;

[0036] Decaglycerol decaestearate, CAS No. 39529-26-5;

[0037] Glycerol monostearate, CAS No. 123-94-4;

[0038] Polyvinyl alcohol, CAS No. 9002-89-5;

[0039] Citric acid, CAS No. 77-92-9.

[0040] The application will be further described in detail in combination with the examples and comparative examples.

[0041] Preparation Example 1.1

[0042] The preparation method of the impermeable material comprises the following steps:

[0043] Disperse 200 g graphene, 150 g potassium permanganate and 300 mL of 95 wt% sulfuric acid in 10 L deionized water, react at a temperature of 85 °C for 3 h, then slowly add 2.5 L of 30 wt% hydrogen peroxide, centrifuge the precipitate when the color of the material in the system no longer changes, wash the precipitate with 5 wt% sodium hydroxide solution until the supernatant is clear, 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, ultrasonic treat at a power of 800 W for 30 min, and reserve; mix 2000 mL of the above activated graphene aqueous solution, 1.8 kg of functional monomer (2-acrylamide-2-methylpropanesulfonic acid) and 2.7 g of potassium persulfate, react at a pH of 9.5 and a temperature of 85 °C for 6 h, cool, filter to obtain a solid, wash with methanol, then dry at a temperature of 105 °C, grind to 300 mesh, and obtain a permeation-preventing material.

[0044] Preparation Example 1.2

[0045] A method for preparing a permeation-preventing material, comprising the following steps:

[0046] Disperse 200 g graphene, 150 g potassium permanganate and 300 mL of 95 wt% sulfuric acid in 10 L deionized water, react at a temperature of 85 °C for 3 h, then slowly add 2.5 L of 30 wt% hydrogen peroxide, centrifuge the precipitate when the color of the material in the system no longer changes, wash the precipitate with 5 wt% sodium hydroxide solution until the supernatant is clear, 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, ultrasonic treat at a power of 800 W for 30 min, and reserve; mix 2000 mL of the above activated graphene aqueous solution, 1.9 kg of functional monomer (sodium p-styrenesulfonate) and 2.7 g of potassium persulfate, react at a pH of 8.5 and a temperature of 95 °C for 4 h, cool, filter to obtain a solid, wash with methanol, then dry at a temperature of 105 °C, grind to 325 mesh, and obtain a permeation-preventing material.

[0047] Preparation Example 2.1

[0048] A method for preparing a permeation-preventing material, which is different from Preparation Example 1.1 in that 1.8 kg of 2-acrylamide-2-methylpropanesulfonic acid is replaced by 0.45 kg of 2-acrylamide-2-methylpropanesulfonic acid and 1.35 kg of sodium p-styrenesulfonate, and the rest is the same as Preparation Example 1.1.

[0049] Preparation Example 2.2

[0050] The method of preparing the barrier material differs from 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 is the same as Preparation Example 1.1.

[0051] Preparation Example 2.3

[0052] The method of preparing the barrier material differs from 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 is the same as Preparation Example 1.1.

[0053] Preparation Example 2.4

[0054] The method of preparing the barrier material differs from 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 is the same as Preparation Example 1.1.

[0055] Preparation Example 3.1

[0056] The method of preparing the lubricant comprises the following steps:

[0057] Ethylene bis-stearamide 1 kg is warmed and melted under the condition of nitrogen protection, then 180 g of glacial acetic acid is added, and the reaction is kept at a temperature of 200 ℃ for 4 h. After cooling, the solid is filtered, washed, dried, and ground to 300 mesh to obtain the lubricant.

[0058] Preparation Example 3.2

[0059] The method of preparing the lubricant comprises the following steps:

[0060] Ethylene bis-stearamide 1 kg is warmed and melted under the condition of nitrogen protection, then 220 g of glacial acetic acid is added, and the reaction is kept at a temperature of 190 ℃ for 5 h. After cooling, the solid is filtered, washed, dried, and ground to 325 mesh to obtain the lubricant.

[0061] Preparation Example 3.3

[0062] The method of preparing the lubricant differs from Preparation Example 3.1 in that the amount of glacial acetic acid is 190 g, and the rest is the same as Preparation Example 1.1.

[0063] Preparation Example 3.4

[0064] The method of preparing the lubricant differs from Preparation Example 3.1 in that the amount of glacial acetic acid is 200 g, and the rest is the same as Preparation Example 1.1.

[0065] Preparation Example 3.5

[0066] The preparation method of the lubricant is different from that of Preparation Example 3.1 in that the amount of glacial acetic acid is 210 g, and the rest is the same as that of Preparation Example 1.1.

[0067] Example 1.1

[0068] A preparation method of a coating agent for expandable polystyrene particles, comprising the following steps:

[0069] Blend 300 g of a film former (polyvinyl alcohol), 300 g of an emulsifier (100 g of decaglycerol decastearate and 200 g of glycerol monostearate), 350 g of a lubricant (ethylene bis-stearamide), and 100 g of the impermeable material prepared in Preparation Example 1.1, and grind at 25°C until the particle size is 325 mesh to obtain a coating agent for expandable polystyrene particles.

[0070] Example 1.2

[0071] A preparation method of a coating agent for expandable polystyrene particles, comprising the following steps:

[0072] Blend 200 g of a film former (polyvinyl alcohol), 400 g of an emulsifier (200 g of decaglycerol decastearate and 200 g of glycerol monostearate), 300 g of a lubricant (ethylene bis-stearamide), and 150 g of the impermeable material prepared in Preparation Example 1.2, and grind at 20°C until the particle size is 300 mesh to obtain a coating agent for expandable polystyrene particles.

[0073] Example 1.3

[0074] A preparation method of a coating agent for expandable polystyrene particles, comprising the following steps:

[0075] Blend 280 g of a film former (polyvinyl alcohol), 370 g of an emulsifier (150 g of decaglycerol decastearate and 220 g of glycerol monostearate), 330 g of a lubricant (ethylene bis-stearamide), and 120 g of the impermeable material prepared in Preparation Example 1.1, and grind at 22°C until the particle size is 325 mesh to obtain a coating agent for expandable polystyrene particles.

[0076] Examples 2.1-2.4

[0077] A preparation method of a coating agent for expandable polystyrene particles, which is different from Example 1.3 in that the impermeable material prepared in Preparation Example 1.1 is replaced by the impermeable material prepared in Preparation Examples 2.1-2.4, respectively, and the rest is the same as that of Example 1.3.

[0078] Example 3.1

[0079] A method for preparing a coating agent for expandable polystyrene particles, which is different from Example 1.3 in that 200 g of polyvinyl alcohol and 80 g of citric acid are used instead of polyvinyl alcohol, and the rest is the same as Example 1.3.

[0080] Example 3.2

[0081] A method for preparing a coating agent for expandable polystyrene particles, which is different from Example 1.3 in that 107.8 g of polyvinyl alcohol and 172.2 g of citric acid are used instead of polyvinyl alcohol, and the rest is the same as Example 1.3.

[0082] Example 3.3

[0083] A method for preparing a coating agent for expandable polystyrene particles, which is different from Example 1.3 in that 140 g of polyvinyl alcohol and 140 g of citric acid are used instead of polyvinyl alcohol, and the rest is the same as Example 1.3.

[0084] Examples 4.1-4.5

[0085] A method for preparing a coating agent for expandable polystyrene particles, which is different from Example 1.3 in that the ethylene bis-stearamide is replaced by the lubricant prepared in Preparation Example 3.1-3.5, and the rest is the same as Example 1.3.

[0086] Comparative Example 1

[0087] Different from Example 1.3 in that the impermeable material prepared in Preparation Example 1.1 is removed, and the rest is the same as Example 1.3.

[0088] Comparative Example 2

[0089] Different from Example 1.3 in that decaglycerol decastearate is removed, and the amount of glyceryl monostearate is changed to 370 g, and the rest is the same as Example 1.3.

[0090] Comparative Example 3

[0091] Different from Example 1.3 in that glyceryl monostearate is removed, and the amount of decaglycerol decastearate is changed to 370 g, and the rest is the same as Example 1.3.

[0092] Performance test

[0093] The coating agent prepared in the examples and comparative examples was blended with EPS particles (self-made, the tensile strength after the plate was made was 24.4 MPa), the blending weight ratio was controlled to be 0.15:100, the discharge time was 80 min, the mixing time was 100 min, and injection molding was carried out at a temperature of 200 DEG C, to obtain expandable polystyrene particles with a protective coating on the surface, the adhesion degree was judged, and the results are shown in Table 1; then the expandable polystyrene particles with a protective coating on the surface were foamed, and then the tensile strength (MPa) of the sample plate was determined according to the description in GB 9641-1988 "Hard Foam Plastic Tensile Property Test Method", the determination temperature was 25 DEG C, and the clamp moving speed was 5 ± 1 mm / min, and the results are shown in Table 1;

[0094] Note:

[0095] 1. The adhesion degree is classified as:

[0096] 1st, the EPS particles are completely independent, and there is no adhesion;

[0097] 2nd, the EPS particles are slightly adhered, and there is contact between some particles;

[0098] 3rd, the EPS particles are adhered, and there is obvious contact between multiple particles, but they can be separated;

[0099] 4th, the EPS particles are severely adhered, and even form a large block and cannot be separated;

[0100] 2. The blending weight ratio between the coating agent of the application and the EPS particles is only taken as an example of 0.15:100.

[0101] Table 1 Performance Test Table

[0102]

[0103]

[0104] Data analysis:

[0105] As can be seen from Table 1, the adhesion degree of the particles of Examples 1.1-1.3 is only 2nd, and the tensile strength of the sample plate is 26.1-26.8 MPa, which is at least 6.97% higher than that of the particles foamed without adding the coating agent, proving that the coating agent of the application can effectively prevent the penetration of external impurities, protect the internal structure of the particles from being damaged, prolong the service life of the particles, at the same time, can embed into the concave part of the particle surface, further reduce the friction between the particles, form a protective film on the surface of the particles, effectively reduce the direct contact between the particles, thereby reducing the friction and adhesion phenomenon, improving the dispersibility of the particles, reducing the mechanical damage of the particles during transportation and storage, and at the same time, improving the flowability of the particles.

[0106] In Examples 2.1-2.4, the proportion of functional monomers in the preparation of the impermeable material is changed, and the results show that the particle adhesion degree of Examples 2.2-2.3 is lower than that of other examples, and the tensile strength of the sample board is greater, which proves that by optimizing the proportion of functional monomers, the protective ability of the coating agent to the surface of the expandable polystyrene particles is enhanced, the adhesion phenomenon between the particles is effectively prevented, the impermeability of the coating is improved, the influence of water or other external substances on the particles is reduced, and the apparent integrity and service life of the foamed material are further improved.

[0107] In Examples 3.1-3.3, the components and proportions of the film-forming agent are changed, and the results show that the particle adhesion degree is reduced and the tensile strength of the sample board is increased, which proves that by compounding polyvinyl alcohol and citric acid as the film-forming agent according to a specific weight ratio, a uniform and dense protective film can be formed, the overall adhesion and durability of the coating are effectively improved, polyvinyl alcohol provides good film-forming performance, and citric acid enhances the flexibility and weather resistance of the coating, and the two work together to ensure that the coating stably adheres to the surface of the expandable polystyrene particles, reduces the friction and adhesion between the particles, thereby improving the apparent integrity and service life of the foamed material; the data of Example 3.2 is optimal, which proves that the film-forming agent with a weight ratio of polyvinyl alcohol to citric acid of 5:4 not only forms a uniform and dense protective film on the surface of the expandable polystyrene particles, but also effectively enhances the flexibility and adhesion of the coating, reduces the damage to the coating caused by friction between the particles, and better maintains the dispersion state of the particles to prevent adhesion.

[0108] In Examples 4.1-4.5, the composition of the emulsifier is changed, and the results show that the particle adhesion degree is reduced and the tensile strength of the sample board is increased, which proves that by reacting ethylene bis-stearamide and glacial acetic acid under specific conditions, the stability and dispersibility of the lubricant can be significantly improved, the overall stability of the coating agent is enhanced, and the adhesion between the particles is reduced, thereby improving the apparent integrity and service life of the final foamed material.

[0109] In Examples 4.1-4.5, the particle adhesion degree of Example 4.4 is the lowest and the tensile strength of the sample board is the highest, which proves that by optimizing the weight ratio of ethylene bis-stearamide to glacial acetic acid to 1:0.2, the reaction in the preparation process of the lubricant is more complete, and the generated lubricant has more excellent stability and dispersibility. The adjustment of this ratio further improves the effect of the lubricant in the coating agent, enhances the protective ability of the coating agent to the surface of the expandable polystyrene particles, effectively reduces the adhesion between the particles, and improves the uniformity and friction resistance of the coating.

[0110] The degree of particle adhesion of Comparative Example 1 increases, and the tensile strength of the sample decreases, 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 being damaged, prolong the service life of the particles, at the same time, can be embedded in the concave part of the particle surface, further reduce the degree of friction between the particles, and also can improve the overall strength and durability of the coating, so that the coating has better anti-adhesion performance.

[0111] The degree of particle adhesion of Comparative Example 2-3 increases, and the tensile strength of the sample decreases, proving that the present application uses a certain weight ratio of decaglycerol decastearate and glycerol monostearate as an emulsifier, which can further enhance the uniformity and stability of the coating, ensure that the coating is more firmly attached to the surface of the particles, and avoid the coating from falling off due to the movement of the particles.

[0112] The embodiments of the specific implementation are the preferred embodiments of the present application, but do not limit the protection scope of the present application, so: any equivalent changes made according to the structure, shape, 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: 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 impermeable material; the emulsifier includes decaglycerol decastearate and glycerol monostearate in a weight ratio of 1: (1-2), the impermeable material is prepared from functional monomers and activated graphene, the functional monomers include 2-acrylamido-2-methylpropane sulfonic acid and / or sodium p-styrenesulfonate; the film forming agent includes polyvinyl alcohol and citric acid in a weight ratio of 5: (2-8); the lubricant is prepared by the following method: melting ethylene bis-stearamide under the condition of inert gas protection, then adding glacial acetic acid, keeping the reaction at a temperature of 190-200℃ for 4-5h, cooling, filtering to obtain a solid, washing, drying, and grinding to 300-325 mesh to obtain the lubricant, the weight ratio of ethylene bis-stearamide to glacial acetic acid being 1: (0.18-0.22).

2. The expandable polystyrene particle coating agent according to claim 1, characterized by The functional monomers include 2-acrylamido-2-methylpropane sulfonic acid and sodium p-styrenesulfonate in a weight ratio of 1: (1.5-2).

3. The expandable polystyrene particle coating agent according to claim 1, wherein The preparation method of the impermeable material includes the following steps: dispersing activated graphene, functional monomers and potassium persulfate in water, reacting at a pH of 8.5-9.5 and a temperature of 85-95℃ for 4-6h, cooling, filtering to obtain a solid, washing, drying, and grinding to 300-325 mesh to obtain the impermeable material, the weight ratio of activated graphene to functional monomers being (180-190):

1.

4. The expandable polystyrene particle coating agent according to claim 1, characterized by The raw materials used include the following components in parts by weight: 28 parts of a film forming agent; 37 parts of an emulsifier; 33 parts of a lubricant; 12 parts of an impermeable material.

5. The expandable polystyrene particle coating agent according to claim 1, wherein The weight ratio of the polyvinyl alcohol to citric acid is 5:

5.

6. The expandable polystyrene particle coating agent according to claim 1, wherein The weight ratio of the ethylene bis-stearamide to glacial acetic acid is 1:0.

2.

7. A process for preparing a coating agent for expandable polystyrene particles as claimed in any one of claims 1 to 6, characterized in that, The method includes the following steps: blending all the raw materials and grinding at a temperature of 20-25℃ until the particle size is 300-325 mesh to obtain a coating agent for expandable polystyrene particles.

8. Use of a coating agent for expandable polystyrene particles according to any one of claims 1 to 6, characterized in that Mixing the coating agent for expandable polystyrene particles with expandable polystyrene particles in a weight ratio of (0.1-0.2):100, and injection molding to obtain expandable polystyrene particles with a protective coating on the surface.

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