Foam forming process of compression-resistant waterproof foam box

Abstract

The invention belongs to the technical field of foam forming, and particularly relates to a foam forming process of a pressure-resistant waterproof foam box. The preparation method comprises the following steps: S1, adding foaming raw material components except a foaming agent into mixing equipment, and uniformly stirring and mixing at 60-70 DEG C to obtain a mixture A; s2, adding a foaming agent into the mixture A, and uniformly mixing to obtain a mixture B; s3, the mixture B is injected into a preheated forming mold cavity; after the pressure is maintained for a period of time, the wall thickness of the mold cavity is increased by retreating the movable mold core, in the process, the volume of the material is expanded along with the increase of the space of the mold cavity, foaming is completed, and the whole mold cavity is filled; and S4, cooling and curing the material, and taking out to obtain the foam box. The graphene modified EPS particles are adopted as the main raw material, and a demolding controllable foaming forming process is combined, so that the mechanical strength and the waterproof performance of the material are remarkably improved, and the heat preservation and heat insulation performance of the material is effectively improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of foaming molding, and relates to a foaming molding process for a pressure-resistant and waterproof foam box, and in particular to a lightweight and high-strength waterproof foam box prepared by a demolding controllable foaming molding process using graphene-modified polystyrene particles as a main raw material, which is suitable for application scenarios such as logistics packaging, food preservation, and electronic product protection. Background Art

[0002] In recent years, with the rapid development of e-commerce and express logistics industries, the demand for packaging materials has been growing, especially the demand for lightweight packaging materials with excellent compressive resistance, good waterproofness and thermal insulation properties.

[0003] Although traditional polystyrene foam (EPS) boxes have certain lightweight and cushioning properties, they still have some shortcomings in practical applications, such as low compressive strength, poor waterproof performance, and high thermal conductivity, which to a certain extent limit their application in high-end fields.

[0004] The commonly used methods to improve the performance of EPS in the market mainly include adding various modifiers or reinforcing materials. However, these methods are often difficult to improve the mechanical strength, waterproof performance and thermal insulation performance of the material at the same time, and are prone to problems such as uneven foaming and high internal stress of the product during processing, which affects the quality and performance of the final product. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a foaming molding process for a pressure-resistant and waterproof foam box.

[0006] The purpose of the present invention is to provide a new type of pressure-resistant and waterproof foam box and its foaming molding process in view of the above problems existing in the prior art. The foam box adopts graphene-modified EPS particles as the main raw material and combines the mold-removing controllable foaming molding process, which not only significantly improves the mechanical strength and waterproof performance of the material, but also effectively improves the thermal insulation performance of the material.

[0007] The foaming molding process of the pressure-resistant and waterproof foam box provided by the present invention comprises the following steps:

[0008] Step S1: Add the foaming raw material components except the foaming agent into a mixing device, stir and mix them evenly at 60-70° C. to obtain a mixture A;

[0009] Step S2: adding a foaming agent to the mixture A and mixing evenly to obtain a mixture B;

[0010] Step S3: injecting the mixture B into the preheated molding mold cavity; after holding the pressure for a period of time, the wall thickness of the mold cavity is increased by retreating the movable mold core. During this process, the volume of the material expands as the cavity space increases, and the foaming is completed and fills the entire cavity;

[0011] Step S4: The material is cooled and solidified, and then taken out to obtain a foam box.

[0012] As a further optimization scheme for the above-mentioned foaming molding process: in step S3, the mixture B is injected into the molding mold cavity which has been preheated to 105-115°C at a speed of 300-400 mm / s, and the injection pressure is controlled between 120-145 MPa; after the injection is completed, a pressure of 10-20 MPa is applied and maintained for 2-3 seconds to allow the material to fully fill the mold; then, the mold cavity wall thickness is increased by retreating the movable mold core. During this process, the material expands in volume as the cavity space increases, completing the foaming and evenly filling the entire cavity.

[0013] As a further optimization scheme of the above foaming molding process: in step S3, the linear speed of the moving mold core retreating is 3-5 mm / s, and the wall thickness is enlarged by 5-10 times.

[0014] As a further optimization solution for the above foaming molding process: the raw materials used in the foaming molding process include:

[0015] Modified EPS particles: 100 parts by mass;

[0016] Styrene-acrylonitrile copolymer: 40-80 parts by mass;

[0017] Polyurethane prepolymer: 15-30 parts by mass;

[0018] Redispersible latex powder: 10-15 parts by mass;

[0019] Hydroxypropyl methylcellulose ether: 5-10 parts by weight;

[0020] Polypropylene fiber: 3-6 parts by mass;

[0021] Silicone waterproofing agent: 10-20 parts by mass;

[0022] Foaming agent: 15-25 parts by mass.

[0023] As a further optimization solution for the above foaming molding process: the modified EPS particles are graphene-modified EPS particles.

[0024] As a further optimization scheme of the above foaming molding process: the modified EPS particles are prepared by the following steps:

[0025] Step K1: Sodium borohydride, graphene flakes and alkylbenzene sulfonic acid are mixed in a mass ratio of 10:1-2:5-8 and then treated in an ice bath to obtain material A;

[0026] Step K2: Add 0.02-0.1 times the mass of material A to material A and heat to 50-60° C. to react for 20-40 minutes to obtain material B;

[0027] Step K3: Material B is mixed with styrene monomer in an amount of 0.1-0.5 times the mass of material B, and polymerized into polystyrene particles by suspension polymerization at a reaction temperature of 80-90° C. to obtain material C;

[0028] Step K4: polymerizing and foaming material C with n-pentane in an amount of 0.5-0.8 times the mass of material C at room temperature and pressure to obtain graphene-modified polystyrene foam particles;

[0029] Step K5: heating and pressurizing the modified foamed particles to prepare particles at a temperature of 105-110° C. and a pressure of 1.5-2 atmospheres.

[0030] As a further optimization scheme for the above foaming molding process: in step K3, the initiator used for suspension polymerization to form polystyrene particles is azobisisobutyronitrile, and the amount used is 0.01-0.03 times the mass of styrene monomer; the suspending agent used is polyvinyl alcohol, and the amount used is 0.1-0.3 times the mass of styrene monomer; the stirring speed is 500-750rpm, and the reaction time is 60-120min.

[0031] As a further optimization scheme of the above foaming molding process: the heat deformation temperature of styrene-acrylonitrile copolymer is 105-115°C.

[0032] As a further optimization solution for the above foaming molding process: the organic silicone waterproofing agent is hydrogenated silicone oil HTN-004.

[0033] As a further optimization scheme for the above foaming molding process: the polyurethane prepolymer is a polyether type; the average particle size of the redispersible latex powder is 50-100 μm; the viscosity of the hydroxypropyl methylcellulose ether is 15 mPa.s-30 mPa.s; the equivalent diameter of the polypropylene fiber is 28-70 μm, and the length is 3-200 mm.

[0034] Beneficial Effects

[0035] The present invention successfully prepares a lightweight foam box with excellent compression resistance and waterproof properties through a controllable foaming molding process of mold withdrawal expansion and a specific raw material combination, which helps to reduce transportation costs and improve environmental protection effects.

[0036] The present invention adopts graphene-modified EPS particles, which not only enhances the mechanical strength of the foam box, but also improves its thermal insulation performance. In addition, the mold cavity space is gradually enlarged by moving the movable mold backward, ensuring the uniform expansion of the material in the mold cavity, forming a more uniform and dense bubble structure, effectively reducing defects in the product, and improving the overall performance of the foam box. DETAILED DESCRIPTION

[0037] The foaming process of the pressure-resistant and waterproof foam box includes the following steps:

[0038] Step S1: First, in a mixing device, add the foaming raw material components except the foaming agent, and perform preliminary mixing at 60-70° C. and a stirring speed of 300-600 rpm until a uniform mixture A is obtained.

[0039] Step S2: maintaining the same temperature and stirring rate, after the mixture A is premixed uniformly, gradually adding the foaming agent and continuously stirring to ensure that the foaming agent is evenly distributed in the mixture A, thereby forming a mixture B.

[0040] Step S3: Subsequently, the mixture B is injected into the molding mold cavity preheated to 105-115°C at a speed of 300-400 mm / s, and the injection pressure is controlled between 120-145 MPa. After the injection is completed, a pressure of 10-20 MPa is applied for 2-3 seconds to ensure that the material fully fills the mold. Next, the mold cavity wall thickness is increased by retreating the moving mold core at a speed of 3-5 mm / s, and the wall thickness expansion ratio is 5-10 times. In this process, the material expands in volume as the cavity space increases, completes foaming and evenly fills the entire cavity.

[0041] Step S4: After the foaming process is completed, the product is naturally cooled and solidified in the mold. Finally, the finished product is taken out from the mold to obtain a lightweight foam box with excellent compression resistance and waterproof properties.

[0042] The raw materials used in the foaming molding process of the above-mentioned pressure-resistant and waterproof foam box include:

[0043] Modified EPS particles: 100 parts by mass

[0044] Styrene-acrylonitrile copolymer: 40-80 parts by mass

[0045] Polyurethane prepolymer: 15-30 parts by mass

[0046] Redispersible latex powder: 10-15 parts by mass

[0047] Hydroxypropyl methylcellulose ether: 5-10 parts by weight

[0048] Polypropylene fiber: 3-6 parts by weight

[0049] Silicone waterproofing agent: 10-20 parts by weight

[0050] Foaming agent: 15-25 parts by mass

[0051] The modified EPS particles are graphene-modified EPS particles, which are prepared by the following steps:

[0052] Step K1: Sodium borohydride, graphene flakes and alkylbenzene sulfonic acid are mixed in a mass ratio of 10:1-2:5-8 and then treated in an ice bath to obtain material A;

[0053] Step K2: Add 0.02-0.1 times the mass of material A to material A and heat to 50-60° C. for reaction for 20-40 min to obtain material B;

[0054] Step K3: Material B is mixed with styrene monomer in an amount of 0.1-0.5 times the mass of material B, and polymerized into polystyrene particles by suspension polymerization method, and the reaction temperature is 80-90° C.; wherein the initiator is azobisisobutyronitrile, and the amount used is 0.01-0.03 times the mass of the styrene monomer; the suspending agent is polyvinyl alcohol, and the amount used is 0.1-0.3 times the mass of the styrene monomer; the stirring speed is 500-750rpm, and the reaction time is 60-120min, to obtain material C;

[0055] Step K4: polymerizing and foaming material C with n-pentane in an amount of 0.5-0.8 times the mass of material C at room temperature and pressure to obtain graphene-modified polystyrene foam particles;

[0056] Step K5: heating and pressurizing the modified foamed particles to prepare particles at a temperature of 105-110° C. and a pressure of 1.5-2 atmospheres.

[0057] in,

[0058] The heat distortion temperature of styrene-acrylonitrile copolymer is 105-115°C;

[0059] The polyurethane prepolymer is of polyether type;

[0060] The average particle size of the redispersible latex powder is 50-100 μm;

[0061] The viscosity of hydroxypropyl methylcellulose ether is 15mPa.s-30mPa.s;

[0062] The equivalent diameter of the polypropylene fiber is 28-70 μm and the length is 3-200 mm;

[0063] The organic silicon waterproofing agent is hydrogenated silicone oil HTN-004.

[0064] The present invention is further illustrated by specific examples below. These examples are exemplary and are intended to illustrate the problem and explain the present invention, but are not intended to be limiting.

[0065] Raw materials used in each example

[0066] EPS particles were purchased from Wen'an County Yingtong Environmental Protection Technology Co., Ltd., type A foam particles, with a thermal conductivity of 0.030 W / (m·K).

[0067] Styrene-acrylonitrile copolymer AS (SAN) was Formosa Chemicals NF2200AR purchased from Dongguan Baojia Plastic Co., Ltd.

[0068] Polyurethane prepolymer (MDI / TDI terminated, casting type, polyether type, CAS No.: 103837-45-2) was purchased from Hubei Xinyuhong Biopharmaceutical Technology Co., Ltd.

[0069] Redispersible latex powder was purchased from Hebei Chaoyan New Material Technology Co., Ltd.

[0070] Hydroxypropyl methylcellulose ether was purchased from Jinzhou Xincheng Cellulose Co., Ltd.

[0071] Polypropylene fiber was purchased from Xinfeng Cellulose Factory, Hanzhuang, Dacheng County.

[0072] The organosilicon waterproofing agent was purchased from Jiangxi Hongshi New Materials Co., Ltd., with a hydrogen content of 1.6 wt%.

[0073] The foaming agent was purchased from Shanghai Ruiyi Environmental Protection Technology Co., Ltd., brand Enasolv fs39.

[0074] Example 1

[0075] Step S1: First, in a mixing device, add the foaming raw material components except the foaming agent, and perform preliminary mixing at 65° C. and a stirring speed of 500 rpm until a uniform mixture A is obtained.

[0076] Step S2: maintaining the same temperature and stirring rate, after the mixture A is premixed uniformly, gradually adding the foaming agent and continuously stirring to ensure that the foaming agent is evenly distributed in the mixture A, thereby forming a mixture B.

[0077] Step S3: Subsequently, the mixture B is injected into the molding mold cavity preheated to 105°C at a speed of 300 mm / s, and the injection pressure is controlled to 120 MPa. After the injection is completed, a pressure of 10 MPa is applied for 2 seconds to ensure that the material fully fills the mold. Next, the mold cavity wall thickness is increased by retreating the moving mold core at a speed of 3 mm / s, and the wall thickness expansion ratio is 5 times. In this process, the material expands in volume as the cavity space increases, completes foaming and evenly fills the entire cavity.

[0078] Step S4: After the foaming process is completed, the product is naturally cooled and solidified in the mold. Finally, the finished product is taken out from the mold to obtain a lightweight foam box with excellent compression resistance and waterproof properties.

[0079] Raw materials used in foaming process:

[0080] Modified EPS particles 100 parts by mass

[0081] 40 parts by mass of styrene-acrylonitrile copolymer

[0082] Polyurethane prepolymer 15 parts by mass

[0083] Redispersible latex powder 10 parts by mass

[0084] 5 parts by mass of Hydroxypropyl methylcellulose ether

[0085] 3 parts by weight of polypropylene fiber

[0086] 10 parts by weight of silicone waterproofing agent

[0087] Foaming agent 15 parts by mass

[0088] The modified EPS particles are graphene-modified EPS particles.

[0089] The modified EPS particles are prepared by the following steps:

[0090] Step K1: Sodium borohydride, graphene flakes and alkylbenzene sulfonic acid are mixed in a mass ratio of 10:1:5 and then treated in an ice bath to obtain material A;

[0091] Step K2: Add 0.02 times the mass of hydrazine as much as that of material A to material A and heat to 50-60° C. for reaction for 20-40 min to obtain material B;

[0092] Step K3: Material B is mixed with styrene monomer in an amount of 0.1 times the mass of material B, and polymerized into polystyrene particles by suspension polymerization method, and the reaction temperature is 80-90° C.; wherein the initiator is azobisisobutyronitrile, and the amount used is 0.01 times the mass of the styrene monomer; the suspending agent is polyvinyl alcohol, and the amount used is 0.1 times the mass of the styrene monomer; the stirring speed is 500-750rpm, and the reaction time is 60-120min, to obtain material C;

[0093] Step K4: polymerizing and foaming material C with n-pentane having a mass 0.5 times the mass of material C at room temperature and pressure to obtain graphene-modified polystyrene foam particles;

[0094] Step K5: heating and pressurizing the modified expanded particles to prepare particles, preferably at a temperature of 105-110° C. and a pressure of 1.5-2 atmospheres.

[0095] The heat distortion temperature of styrene-acrylonitrile copolymer is 112°C;

[0096] The polyurethane prepolymer is of polyether type;

[0097] The average particle size of the redispersible latex powder is 60 μm;

[0098] The viscosity of hydroxypropyl methylcellulose ether is 20mPa.s;

[0099] The equivalent diameter of the polypropylene fiber is 50 μm and the length is 120 mm;

[0100] The organic silicon waterproofing agent is hydrogenated silicone oil HTN-004.

[0101] Example 2

[0102] Step S1: First, in a mixing device, add the foaming raw material components except the foaming agent, and perform preliminary mixing at 65° C. and a stirring speed of 500 rpm until a uniform mixture A is obtained.

[0103] Step S2: maintaining the same temperature and stirring rate, after the mixture A is premixed uniformly, gradually adding the foaming agent and continuously stirring to ensure that the foaming agent is evenly distributed in the mixture A, thereby forming a mixture B.

[0104] Step S3: Subsequently, the mixture B is injected into the molding mold cavity preheated to 115°C at a speed of 400 mm / s, and the injection pressure is controlled to 145 MPa. After the injection is completed, a pressure of 20 MPa is applied for 3 seconds to ensure that the material fully fills the mold. Next, the mold cavity wall thickness is increased by retreating the moving mold core at a speed of 5 mm / s, and the wall thickness expansion ratio is 10 times. In this process, the material expands in volume as the cavity space increases, completes foaming and evenly fills the entire cavity.

[0105] Step S4: After the foaming process is completed, the product is naturally cooled and solidified in the mold. Finally, the finished product is taken out from the mold to obtain a lightweight foam box with excellent compression resistance and waterproof properties.

[0106] Raw materials used in foaming process:

[0107] Modified EPS particles 100 parts by mass

[0108] 60 parts by mass of styrene-acrylonitrile copolymer

[0109] Polyurethane prepolymer 20 parts by mass

[0110] Redispersible latex powder 13 parts by mass

[0111] 8 parts by mass of Hydroxypropyl methylcellulose ether

[0112] Polypropylene fiber 5 parts by mass

[0113] 15 parts by mass of silicone waterproofing agent

[0114] Foaming agent 20 parts by mass

[0115] The modified EPS particles are graphene-modified EPS particles.

[0116] The modified EPS particles are prepared by the following steps:

[0117] Step K1: Sodium borohydride, graphene flakes and alkylbenzene sulfonic acid are mixed in a mass ratio of 10:1.5:6 and then treated in an ice bath to obtain material A;

[0118] Step K2: Add 0.05 times the mass of hydrazine as material A to material A and heat to 50-60° C. for reaction for 20-40 min to obtain material B;

[0119] Step K3: Material B is mixed with styrene monomer in an amount of 0.3 times the mass of material B, and polymerized into polystyrene particles by suspension polymerization method, and the reaction temperature is 80-90° C.; wherein the initiator is azobisisobutyronitrile, and the amount used is 0.02 times the mass of the styrene monomer; the suspending agent is polyvinyl alcohol, and the amount used is 0.2 times the mass of the styrene monomer; the stirring speed is 500-750rpm, and the reaction time is 60-120min, to obtain material C;

[0120] Step K4: polymerizing and foaming material C with n-pentane in an amount 0.65 times the mass of material C at room temperature and pressure to obtain graphene-modified polystyrene foam particles;

[0121] Step K5: heating and pressurizing the modified expanded particles to prepare particles, preferably at a temperature of 105-110° C. and a pressure of 1.5-2 atmospheres.

[0122] The heat distortion temperature of styrene-acrylonitrile copolymer is 112°C;

[0123] The polyurethane prepolymer is of polyether type;

[0124] The average particle size of the redispersible latex powder is 60 μm;

[0125] The viscosity of hydroxypropyl methylcellulose ether is 20mPa.s;

[0126] The equivalent diameter of the polypropylene fiber is 50 μm and the length is 120 mm;

[0127] The organic silicon waterproofing agent is hydrogenated silicone oil HTN-004.

[0128] Example 3

[0129] Step S1: First, in a mixing device, add the foaming raw material components except the foaming agent, and perform preliminary mixing at 65° C. and a stirring speed of 500 rpm until a uniform mixture A is obtained.

[0130] Step S2: maintaining the same temperature and stirring rate, after the mixture A is premixed uniformly, gradually adding the foaming agent and continuously stirring to ensure that the foaming agent is evenly distributed in the mixture A, thereby forming a mixture B.

[0131] Step S3: Subsequently, the mixture B is injected into the molding mold cavity preheated to 110°C at a speed of 350 mm / s, and the injection pressure is controlled to 130 MPa. After the injection is completed, a pressure of 15 MPa is applied for 2.5 seconds to ensure that the material fully fills the mold. Then, the mold cavity wall thickness is increased by retreating the moving mold core at a speed of 4 mm / s, and the wall thickness expansion ratio is 8 times. In this process, the material expands in volume as the cavity space increases, completes foaming and evenly fills the entire cavity.

[0132] Step S4: After the foaming process is completed, the product is naturally cooled and solidified in the mold. Finally, the finished product is taken out from the mold to obtain a lightweight foam box with excellent compression resistance and waterproof properties.

[0133] Raw materials used in foaming process:

[0134] Modified EPS particles 100 parts by mass

[0135] 80 parts by mass of styrene-acrylonitrile copolymer

[0136] Polyurethane prepolymer 30 parts by mass

[0137] Redispersible latex powder 15 parts by mass

[0138] Hydroxypropyl methylcellulose ether 10 parts by mass

[0139] Polypropylene fiber 6 parts by mass

[0140] 20 parts by weight of silicone waterproofing agent

[0141] Foaming agent 25 parts by mass

[0142] The modified EPS particles are graphene-modified EPS particles.

[0143] The modified EPS particles are prepared by the following steps:

[0144] Step K1: Sodium borohydride, graphene flakes and alkylbenzene sulfonic acid are mixed in a mass ratio of 10:2:8 and then treated in an ice bath to obtain material A;

[0145] Step K2: Add hydrazine in an amount 0.1 times the mass of material A to material A and heat to 50-60° C. for reaction for 20-40 min to obtain material B;

[0146] Step K3: Material B is mixed with styrene monomer in an amount of 0.5 times the mass of material B, and polymerized into polystyrene particles by suspension polymerization method, and the reaction temperature is 80-90° C.; wherein the initiator is azobisisobutyronitrile, and the amount used is 0.03 times the mass of the styrene monomer; the suspending agent is polyvinyl alcohol, and the amount used is 0.3 times the mass of the styrene monomer; the stirring speed is 500-750rpm, and the reaction time is 60-120min, to obtain material C;

[0147] Step K4: polymerizing and foaming material C with n-pentane having a mass 0.8 times that of material C at room temperature and pressure to obtain graphene-modified polystyrene foam particles;

[0148] Step K5: heating and pressurizing the modified expanded particles to prepare particles, preferably at a temperature of 105-110° C. and a pressure of 1.5-2 atmospheres.

[0149] The heat distortion temperature of styrene-acrylonitrile copolymer is 112°C;

[0150] The polyurethane prepolymer is of polyether type;

[0151] The average particle size of the redispersible latex powder is 60 μm;

[0152] The viscosity of hydroxypropyl methylcellulose ether is 20mPa.s;

[0153] The equivalent diameter of the polypropylene fiber is 50 μm and the length is 120 mm;

[0154] The organic silicon waterproofing agent is hydrogenated silicone oil HTN-004.

[0155] Comparative Example 1

[0156] Step S1: First, in a mixing device, add the foaming raw material components except the foaming agent, and perform preliminary mixing at 65° C. and a stirring speed of 500 rpm until a uniform mixture A is obtained.

[0157] Step S2: maintaining the same temperature and stirring rate, after the mixture A is premixed uniformly, gradually adding the foaming agent and continuously stirring to ensure that the foaming agent is evenly distributed in the mixture A, thereby forming a mixture B.

[0158] Step S3: Subsequently, the mixture B is injected into the molding mold cavity preheated to 110°C at a speed of 350 mm / s, and the injection pressure is controlled to 130 MPa. After the injection is completed, a pressure of 15 MPa is applied for 2.5 seconds to ensure that the material fully fills the mold. Then, the mold cavity wall thickness is increased by retreating the moving mold core at a speed of 4 mm / s, and the wall thickness expansion ratio is 8 times. In this process, the material expands in volume as the cavity space increases, completes foaming and evenly fills the entire cavity.

[0159] Step S4: After the foaming process is completed, the product is naturally cooled and solidified in the mold. Finally, the finished product is taken out from the mold to obtain a lightweight foam box with excellent compression resistance and waterproof properties.

[0160] Raw materials used in foaming process:

[0161] EPS particles 100 parts by mass

[0162] 60 parts by mass of styrene-acrylonitrile copolymer

[0163] Polyurethane prepolymer 20 parts by mass

[0164] Redispersible latex powder 13 parts by mass

[0165] 8 parts by mass of Hydroxypropyl methylcellulose ether

[0166] Polypropylene fiber 5 parts by mass

[0167] 15 parts by mass of silicone waterproofing agent

[0168] Foaming agent 20 parts by mass

[0169] The heat distortion temperature of styrene-acrylonitrile copolymer is 112°C;

[0170] The polyurethane prepolymer is of polyether type;

[0171] The average particle size of the redispersible latex powder is 60 μm;

[0172] The viscosity of hydroxypropyl methylcellulose ether is 20mPa.s;

[0173] The equivalent diameter of the polypropylene fiber is 50 μm and the length is 120 mm;

[0174] The organic silicon waterproofing agent is hydrogenated silicone oil HTN-004.

[0175] Compared with Example 2, this comparative example does not use modified EPS particles, but uses ordinary EPS particles.

[0176] Comparative Example 2

[0177] Step S1: First, in a mixing device, add the foaming raw material components except the foaming agent, and perform preliminary mixing at 65° C. and a stirring speed of 500 rpm until a uniform mixture A is obtained.

[0178] Step S2: maintaining the same temperature and stirring rate, after the mixture A is premixed uniformly, gradually adding the foaming agent and continuously stirring to ensure that the foaming agent is evenly distributed in the mixture A, thereby forming a mixture B.

[0179] Step S3: Subsequently, the mixture B is injected into the molding mold cavity preheated to 110°C at a speed of 350 mm / s, and the injection pressure is controlled to 130 MPa. After the injection is completed, a pressure of 15 MPa is applied for 2.5 seconds to ensure that the material fully fills the mold. Then, the mold cavity wall thickness is increased by retreating the moving mold core at a speed of 4 mm / s, and the wall thickness expansion ratio is 8 times. In this process, the material expands in volume as the cavity space increases, completes foaming and evenly fills the entire cavity.

[0180] Step S4: After the foaming process is completed, the product is naturally cooled and solidified in the mold. Finally, the finished product is taken out from the mold to obtain a lightweight foam box with excellent compression resistance and waterproof properties.

[0181] Raw materials used in foaming process:

[0182] Modified EPS particles 100 parts by mass

[0183] Polyurethane prepolymer 20 parts by mass

[0184] Redispersible latex powder 13 parts by mass

[0185] 8 parts by mass of Hydroxypropyl methylcellulose ether

[0186] Polypropylene fiber 5 parts by mass

[0187] 15 parts by mass of silicone waterproofing agent

[0188] Foaming agent 20 parts by mass

[0189] The modified EPS particles are graphene-modified EPS particles.

[0190] The modified EPS particles are prepared by the following steps:

[0191] Step K1: Sodium borohydride, graphene flakes and alkylbenzene sulfonic acid are mixed in a mass ratio of 10:1.5:6 and then treated in an ice bath to obtain material A;

[0192] Step K2: Add 0.05 times the mass of hydrazine as material A to material A and heat to 50-60° C. for reaction for 20-40 min to obtain material B;

[0193] Step K3: Material B is mixed with styrene monomer in an amount of 0.3 times the mass of material B, and polymerized into polystyrene particles by suspension polymerization method, and the reaction temperature is 80-90° C.; wherein the initiator is azobisisobutyronitrile, and the amount used is 0.02 times the mass of the styrene monomer; the suspending agent is polyvinyl alcohol, and the amount used is 0.2 times the mass of the styrene monomer; the stirring speed is 500-750rpm, and the reaction time is 60-120min, to obtain material C;

[0194] Step K4: polymerizing and foaming material C with n-pentane in an amount 0.65 times the mass of material C at room temperature and pressure to obtain graphene-modified polystyrene foam particles;

[0195] Step K5: heating and pressurizing the modified expanded particles to prepare particles, preferably at a temperature of 105-110° C. and a pressure of 1.5-2 atmospheres.

[0196] The polyurethane prepolymer is of polyether type;

[0197] The average particle size of the redispersible latex powder is 60 μm;

[0198] The viscosity of hydroxypropyl methylcellulose ether is 20mPa.s;

[0199] The equivalent diameter of the polypropylene fiber is 50 μm and the length is 120 mm;

[0200] The organic silicon waterproofing agent is hydrogenated silicone oil HTN-004.

[0201] Compared to Example 2, this comparative example lacks the styrene-acrylonitrile copolymer.

[0202] Test Case

[0203] The foam boxes prepared in each embodiment were sampled and cut into experimental blocks of 10 cm×5 cm×2 cm (thickness). The apparent density, thermal insulation performance and mechanical strength of the experimental blocks were tested. The apparent density unit is g / cm 3 . The lower the apparent density, the lighter the material and the more raw materials are saved. The thermal insulation performance is measured by thermal conductivity (λ), with the unit of W / (m·K). The lower the thermal conductivity, the better the thermal insulation performance of the thermal insulation material. The mechanical properties are tested by compressive strength (Mpa) and tensile strength (Mpa), referring to GB / T10801.1-2021 "Molded polystyrene foam (EPS) for thermal insulation". The test results are shown in Table 1.

[0204] Table 1 Performance test results

[0205]

[0206] Analysis and Conclusion

[0207] In the above embodiment, the space of the mold cavity is gradually increased by retreating the movable mold, and the material gradually expands in the mold cavity to form a uniform bubble structure, thereby avoiding the uneven size and distribution of bubbles caused by instantaneous expansion, thereby improving the uniformity and density of the foam. This progressive expansion process helps to reduce defects such as continuous holes or large holes in the product, improve the waterproof performance of the material, improve the density and structural stability of the material, and enhance its compressive performance and tensile strength. In addition, retreating the movable mold can also accurately control the wall thickness and shape of the product, reduce internal stress, and help improve the mechanical properties of the product.

[0208] In addition, the data in Table 1 show that adding the prepared modified EPS particles to the system can greatly improve the mechanical strength of the material. The use of modified EPS particles (graphene-modified EPS particles) significantly improves the mechanical strength of the foam box and also improves its thermal insulation performance. In particular, Example 3, through the use of modified EPS particles, the addition of styrene-acrylonitrile copolymer, the optimization of foaming agents and additives, and the fine control of process parameters, these factors work together to make Example 3 perform well in terms of apparent density, thermal conductivity, compressive strength, and tensile strength.

[0209] The above embodiments are exemplary, and their purpose is to illustrate the technical concept and features of the present invention so that people familiar with the technology in this field can understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A foaming molding process for a pressure-resistant and waterproof foam box, characterized in that: The following steps are involved: Step S1: Add the foaming raw material components except the foaming agent into a mixing device, stir and mix them evenly at 60-70° C. to obtain a mixture A; Step S2: adding a foaming agent to the mixture A and mixing evenly to obtain a mixture B; Step S3: injecting the mixture B into the preheated molding mold cavity; after holding the pressure for a period of time, the wall thickness of the mold cavity is increased by retreating the movable mold core. During this process, the volume of the material expands as the cavity space increases, and the foaming is completed and fills the entire cavity; Step S4: The material is cooled and solidified, and then taken out to obtain a foam box.

2. The foaming molding process of the pressure-resistant and waterproof foam box according to claim 1 is characterized in that: In step S3, the mixture B is injected into the molding mold cavity which has been preheated to 105-115°C at a speed of 300-400 mm / s, and the injection pressure is controlled between 120-145 MPa; after the injection is completed, a pressure of 10-20 MPa is applied and maintained for 2-3 seconds to allow the material to fully fill the mold; then, the mold cavity wall thickness is increased by retreating the movable mold core. During this process, the material expands in volume as the cavity space increases, completes foaming and evenly fills the entire cavity.

3. The foaming molding process of the pressure-resistant and waterproof foam box according to claim 2 is characterized in that: In step S3, the linear speed of the moving mold core retreating is 3-5 mm / s, and the wall thickness is enlarged by 5-10 times.

4. The foaming molding process of the pressure-resistant and waterproof foam box according to any one of claims 1 to 3, characterized in that: The raw materials used in the foaming process include: Modified EPS particles: 100 parts by mass; Styrene-acrylonitrile copolymer: 40-80 parts by mass; Polyurethane prepolymer: 15-30 parts by mass; Redispersible latex powder: 10-15 parts by mass; Hydroxypropyl methylcellulose ether: 5-10 parts by weight; Polypropylene fiber: 3-6 parts by mass; Silicone waterproofing agent: 10-20 parts by mass; Foaming agent: 15-25 parts by mass.

5. The foaming molding process of the pressure-resistant and waterproof foam box according to claim 4 is characterized in that: The modified EPS particles are graphene-modified EPS particles.

6. The foaming process for the pressure-resistant and waterproof foam box according to claim 4, characterized in that: The modified EPS particles are prepared by the following steps: Step K1: Sodium borohydride, graphene flakes and alkylbenzene sulfonic acid are mixed in a mass ratio of 10:1-2:5-8 and then treated in an ice bath to obtain material A; Step K2: Add 0.02-0.1 times the mass of material A to material A and heat to 50-60° C. to react for 20-40 minutes to obtain material B; Step K3: Material B is mixed with styrene monomer in an amount of 0.1-0.5 times the mass of material B, and polymerized into polystyrene particles by suspension polymerization at a reaction temperature of 80-90° C. to obtain material C; Step K4: polymerizing and foaming material C with n-pentane in an amount of 0.5-0.8 times the mass of material C at room temperature and pressure to obtain graphene-modified polystyrene foam particles; Step K5: heating and pressurizing the modified foamed particles to prepare particles at a temperature of 105-110° C. and a pressure of 1.5-2 atmospheres.

7. The foaming molding process of the pressure-resistant and waterproof foam box according to claim 6, characterized in that: In step K3, the initiator used in the suspension polymerization method to polymerize polystyrene particles is azobisisobutyronitrile, and the amount used is 0.01-0.03 times the mass of styrene monomer; the suspending agent used is polyvinyl alcohol, and the amount used is 0.1-0.3 times the mass of styrene monomer; the stirring speed is 500-750rpm, and the reaction time is 60-120min.

8. The foaming molding process of the pressure-resistant and waterproof foam box according to claim 4, characterized in that: The heat deformation temperature of the styrene-acrylonitrile copolymer is 105-115°C.

9. The foaming molding process of the pressure-resistant and waterproof foam box according to claim 4, characterized in that: The organosilicon waterproofing agent is hydrogen-containing silicone oil HTN-004.

10. The foaming molding process of the pressure-resistant and waterproof foam box according to claim 4, characterized in that: The polyurethane prepolymer is of polyether type; the average particle size of the redispersible latex powder is 50-100 μm; the viscosity of the hydroxypropyl methylcellulose ether is 15 mPa.s-30 mPa.s; the equivalent diameter of the polypropylene fiber is 28-70 μm, and the length is 3-200 mm.

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