High-molecular material for safety shoe production and processing and preparation method thereof

Abstract

The application relates to the technical field of safety shoe processing, and discloses a high-molecular material for safety shoe production and processing and a preparation method thereof, which comprises the following steps: after a crystalline saturated polyester resin matrix is preheated and dehydrated, part of foaming aids and deionized water are added, constant-temperature stirring is carried out to obtain a basic premix and the basic premix is stored in an insulation state; antistatic agents are proportionally divided into two groups, and the two groups of antistatic agents are respectively mixed with the remaining foaming aids and deionized water to obtain high-concentration and low-concentration antistatic dispersions which are independently stored in an insulation state; the basic premix is sent into a material cavity of an injection machine, a cross-linking curing agent is added to trigger prepolymerization; after the viscosity of the material liquid reaches a standard, the high-concentration dispersion is mixed into the prepolymerization material liquid, the high-concentration dispersion is injected into the bottom of a mold cavity to a preset thickness, temperature control is carried out to trigger surface layer micro-foaming; the low-concentration dispersion is mixed into the prepolymerization material liquid; after the surface layer foaming reaches a standard, the inner layer material liquid is injected to fill the mold cavity, mold locking is carried out, temperature control is carried out to trigger inner layer foaming; after the mold is locked, the temperature difference between the upper and lower mold cavities is kept constant, then the temperature is increased to complete cross-linking and curing; after the curing, the mold is opened to take out the material, the material is aged after constant-temperature constant-humidity ventilation, and a finished product is obtained.

Description

Technical Field

[0001] This invention relates to the field of safety shoe processing technology, specifically to polymer materials used in the production and processing of safety shoes and their preparation methods. Background Technology

[0002] With the increasing demands for foot protection in industrial settings, the antistatic properties and mechanical durability of multifunctional safety shoe outsoles have become a key focus in the industry. Currently, polymer ester outsoles for safety shoes generally employ a monolithic injection molding process. This involves premixing the base resin, antistatic agent, foaming agent, and curing agent until uniformly blended, then injecting the mixture into a mold to complete foaming and curing in a single step, resulting in a homogeneous outsole material. This process is simple, highly efficient, and widely used in mass production.

[0003] However, when the above-mentioned general process is applied to the preparation of antistatic safety shoe outsoles, there is a problem of mutual incompatibility of component properties. In order to ensure that the antistatic performance of the grounding side of the outsole meets the standards, the process can only increase the overall proportion of antistatic additives to make the additives evenly distributed throughout the entire thickness of the outsole. Excessive additives will interfere with the cross-linking reaction of the polymer ester molecular chains, destroy the micro-cross-linking network inside the material, and directly lead to the degradation of the mechanical properties of the outsole such as wear resistance and tear resistance. At the same time, the inner layer area of ​​the outsole near the upper does not participate in grounding conductivity, and the antistatic additives in this area cannot play a role, resulting in raw material redundancy and cost waste. In addition, high dosage of additives can also easily cause micro-interface defects inside the material, reducing service life.

[0004] Under these limitations, existing homogeneous molding processes cannot simultaneously achieve stable antistatic performance and the material's inherent mechanical strength. If mechanical performance is prioritized over additive usage, antistatic performance may not meet standards; conversely, if additive usage is increased to ensure antistatic performance, the outsole is prone to wear and cracking, reducing protective reliability. Current homogeneous molding approaches cannot address this issue at the level of component spatial distribution, thus hindering the improvement of the overall performance of antistatic safety shoe outsoles. Therefore, the following solutions are proposed to address these problems. Summary of the Invention

[0005] To solve the above-mentioned technical problems, the present invention provides a polymer material for the production and processing of safety shoes and a method for preparing the same, comprising the following steps: Step S1: The polymer ester base raw material is preheated and vacuum dehydrated to reach the preset moisture content. Then, some foaming agent and some deionized water are added, and the mixture is stirred and dispersed at a constant temperature to obtain the base premix. The mixture is then sealed and kept warm for later use. Step S2: Divide the antistatic agent into two groups according to different mass ratios, and mix them with the remaining foaming agent and the remaining deionized water respectively. After stirring and dispersing, high-concentration antistatic dispersion and low-concentration antistatic dilution are prepared respectively. The two dispersions are stored separately in sealed and insulated conditions. Step S3: The basic premix is ​​fed into the injection molding machine cavity and a curing agent is added. The mixture triggers the prepolymerization reaction of the system. After the viscosity of the liquid rises to the preset range, the high-concentration antistatic dispersion is mixed into the surface liquid and mixed evenly. Then the surface mixed liquid is injected into the bottom area of ​​the shoe mold cavity. After the preset filling thickness is reached, the injection is paused and the temperature at the bottom of the mold cavity is controlled to trigger surface micro-foaming. Step S4: Inject the low-concentration antistatic diluent into the main prepolymer liquid in the material cavity, stir and disperse at a constant temperature, and after the surface foaming reaches the preset thickness, inject the inner layer mixture into the upper space of the mold cavity until the mold cavity is completely filled. After completion, immediately lock and close the mold, and control the temperature of the upper part of the mold cavity to trigger the inner layer foaming reaction. Step S5: After locking the mold, maintain the temperature difference between the upper and lower parts of the mold cavity and keep it constant. Then, raise the overall mold temperature to allow the polymer ester system to complete cross-linking and curing, and fix the internal structure. Step S6: After curing, open the mold and remove the molding material, transfer it to a constant temperature and humidity ventilated environment for post-curing treatment, and finally obtain the finished polymer material for safety shoes.

[0006] Preferably, step S1 includes the following steps: Step S11: Nitrogen gas is introduced into the sealed stirred tank to replace the air inside the tank. After adding the polymer ester A material, the jacket heating device is turned on and the material temperature is raised to 45℃~48℃ in a uniform heating mode. During the heating process, the material liquid is continuously stirred at a low speed. At the same time, the vacuum dehydration system is turned on and dehydrated for 22min~25min under a vacuum of -0.085MPa~-0.09MPa. During the dehydration, samples are taken every 5min to test the water content of the material liquid. The vacuum system is turned off when the water content drops below 0.05%. Step S12: First, add 65% of the total mass of the hair hardening agent into the mixing tank, stir and disperse, then add 70% of the total mass of deionized water dropwise. Keep the material temperature constant at 45℃~48℃ throughout the process, maintain a slight positive pressure in the tank, and stir at a speed of 70r / min~75r / min for 9min~10min. After stirring, keep the stirring at a low speed and transfer the basic premix to the heat preservation standby state.

[0007] Preferably, step S2 includes the following steps: Step S21: After filtering the antistatic agent through a sieve, divide it into two groups with a mass ratio of 7:3. The first group is a high-concentration gradient component, and the second group is a low-concentration gradient component. Step S22: Take the high-concentration antistatic agent and the remaining 35% of the hair-styling agent and add them together into a dispersion container preheated to 45°C. Use an axial and radial combined stirring paddle to disperse at a stirring rate of 120 r / min for 6 min to 7 min to obtain a high-concentration antistatic dispersion. Step S23: Take the low concentration of antistatic agent and the remaining 30% of deionized water and add them to another set of preheated dispersion containers. Using the same stirring structure, disperse at a stirring rate of 120 r / min for 5 min to 6 min to obtain a low concentration of antistatic diluted solution. Step S24: Transfer the two dispersions to separate insulated storage tanks and seal them for storage. The storage tank jacket maintains the material temperature at 45°C. During storage, stir at low speed every 10 minutes, with each stirring session lasting 30 seconds.

[0008] Preferably, step S3 includes the following steps: Step S31: The basic premix is ​​quantitatively delivered to the primary material chamber of the injection molding machine using a metering pump. The amount of polyester-specific composite crosslinking curing agent specified in the formula is measured using a loss-in-weight scale and added to the material chamber. The double-layer stirring device built into the material chamber is turned on and mixed at a rate of 90 r / min for 60 s to 70 s to trigger the initial prepolymerization reaction of the system. During the prepolymerization process, the viscosity and temperature data of the liquid are collected in real time, and the temperature fluctuation is controlled within ±1℃. Step S32: When the viscosity of the liquid material rises to 1500 mPa·s to 1800 mPa·s as monitored online, the high-concentration antistatic dispersion is injected through the static mixing element in the distribution channel on the surface of the material chamber and rapidly mixed with the surface prepolymer liquid at a rate of 110 r / min for 30 s. Step S33: After mixing is completed, start the first-level injection program, using a rate curve of slow start-up, medium-speed mold filling, and slow finish-up. Inject the surface mixture liquid into the bottom area of ​​the shoe mold cavity at an injection pressure of 8MPa to 9MPa. Stop the injection after the liquid has filled 40% of the total thickness of the mold cavity and close the bottom inlet valve. Step S34: Open the heating channel of the bottom template of the mold cavity and keep the temperature of the bottom template of the mold cavity at 52℃~55℃ to trigger the micro-foaming reaction of the surface liquid.

[0009] Preferably, step S4 includes the following steps: Step S41: During the pause in injection, inject the low-concentration antistatic diluent into the main prepolymer liquid through the annular inlet on the side wall of the primary material chamber, maintain the material temperature at 48℃~50℃, and stir at a rate of 80r / min for 40s~50s using a double-layer reverse stirring paddle. Step S42: Collect the surface layer foaming thickness data in real time through the optical sensor on the side wall of the mold cavity. When the foaming thickness accounts for 35% of the total thickness of the mold cavity, start the secondary injection program and inject the inner layer mixture into the upper space of the mold cavity at an injection pressure of 6MPa to 7MPa in a gradually increasing manner until the liquid completely fills the mold cavity. Step S43: After injection, perform a graded mold-locking operation. First, close the mold with low pressure until the parting surface is in contact, then gradually increase the mold-locking force to the set value and lock it. Simultaneously, open the heating channel of the upper mold plate of the mold cavity to maintain the temperature of the upper mold plate of the mold cavity at 58℃~60℃.

[0010] Preferably, step S5 includes the following steps: Step S51: After mold clamping, the temperature of the upper and lower mold plates in the mold cavity is controlled by an independent temperature control unit to maintain a temperature difference of 8℃~10℃ between the upper and lower mold plates and maintain the constant temperature for 3min~3.5min; during this stage, the mold cavity remains in a sealed state and the clamping force remains constant. Step S52: Then, the mold cavity is heated in a stepped manner. First, it is heated to 60℃ and held for 2 minutes, then heated to 65℃~68℃ and held for 8 minutes~9 minutes to cure. After curing, the heating system is turned off and the mold cavity is kept in a sealed state to cool down naturally for 1 minute.

[0011] Preferably, step S6 includes the following steps: Step S61: After the curing cycle is completed, the mold cavity is slightly depressurized. After the pressure inside and outside the mold cavity is balanced, the mold is fully opened and the molded polymer material is ejected through the ejector pin mechanism inside the mold. Step S62: Transfer the molding material to the curing rack in the constant temperature and ventilation curing chamber and place it in a single layer with a gap between adjacent materials. Control the curing environment temperature to 40℃~42℃ and the relative humidity to 50%~55%. Use forced circulation ventilation and cure for 24 hours. Record the environmental temperature and humidity parameters every 2 hours during the curing period.

[0012] The polymer material used in the production and processing of safety shoes is prepared by foaming and curing a polymer ester matrix, a foaming agent, a curing agent, an antistatic agent, and deionized water. The antistatic agent forms a gradient distribution with a continuously varying concentration along the thickness direction of the material, and the microporous structure inside the material exhibits a hierarchical distribution with a dense surface layer and a loose inner layer along the thickness direction.

[0013] The polymer materials used in the production and processing of safety shoes include the following components by weight: Polyester matrix 93.3-93.6%, foaming agent 2.0-2.1%, polyester-specific composite crosslinking curing agent 1.7-1.8%, antistatic agent 2.3-2.4%, deionized water 0.35-0.40%.

[0014] The present invention has the following beneficial effects: (1) This invention achieves the distribution of antistatic components along the thickness gradient of the material by separately preparing two antistatic liquids and coordinating with the temperature field control within the mold, which is different from the industry-standard molding mode of uniformly mixing additives. The antistatic components are concentrated on the grounded surface of the material, and the additive content in the inner layer is naturally reduced, eliminating the need for an additional composite antistatic film. While meeting the basic antistatic performance requirements, the overall additive ratio is reduced, which reduces the continuous interference of a large number of antistatic additives on the crosslinking system of the polymer matrix, alleviates the internal micro-defects caused by poor compatibility between additives and matrix, and results in a smaller decline in the antistatic performance of the material during long-term use. The structural integrity of the polymer matrix itself is better maintained, thus improving the conflict between antistatic function and substrate stability from the root cause of the material component distribution.

[0015] (2) This invention relies on the molding logic of segmented injection combined with temperature difference curing in the upper and lower parts of the mold cavity, so that the molded polymer material naturally forms a layered microporous structure with a dense surface layer and a loose inner layer. The two-layer structure is integrally molded by a single injection, and there is no bonding or delamination interface. The dense surface layer can improve the basic anti-friction and anti-tear properties of the material surface, while the loose inner layer provides basic cushioning and rebound capabilities. The two properties are integrated into the whole of a single material. It avoids the defect of interlayer debonding failure after long-term bending of multi-layer composite shoe soles. It can simultaneously have cushioning and shock absorption and surface wear resistance capabilities without the need to add additional cushioning and wear-resistant composite layers, and is suitable for the continuous bending and friction of safety shoe soles.

[0016] (3) The entire gradient structure molding process of this invention is completed in segments within the same injection mold. All premixing, layered injection, and cross-linking curing processes are carried out continuously, eliminating multiple auxiliary processing steps such as independent foaming, layer bonding, and secondary curing, thus shortening the complete production chain. The material flows within the sealed material cavity and mold cavity throughout the entire process, reducing material loss caused by multiple transfers and manual auxiliary processing, while also reducing product structure differences caused by manual operation intervention. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the process for manufacturing and processing the polymer material for safety shoes according to the present invention and its preparation method. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Please see Figure 1 This invention relates to a polymer material for the production and processing of safety shoes and its preparation method, comprising the following steps: Step S1: The polymer ester base raw material is preheated and vacuum dehydrated to reach the preset moisture content. Then, some foaming agent and some deionized water are added, and the mixture is stirred and dispersed at a constant temperature to obtain the base premix. The mixture is then sealed and kept warm for later use. Step S2: Divide the antistatic agent into two groups according to different mass ratios, and mix them with the remaining foaming agent and the remaining deionized water respectively. After stirring and dispersing, high-concentration antistatic dispersion and low-concentration antistatic dilution are prepared respectively. The two dispersions are stored separately in sealed and insulated conditions. Step S3: The basic premix is ​​fed into the injection molding machine cavity and a curing agent is added. The mixture triggers the prepolymerization reaction of the system. After the viscosity of the liquid rises to the preset range, the high-concentration antistatic dispersion is mixed into the surface liquid and mixed evenly. Then the surface mixed liquid is injected into the bottom area of ​​the shoe mold cavity. After the preset filling thickness is reached, the injection is paused and the temperature at the bottom of the mold cavity is controlled to trigger surface micro-foaming. Step S4: Inject the low-concentration antistatic diluent into the main prepolymer liquid in the material cavity, stir and disperse at a constant temperature, and after the surface foaming reaches the preset thickness, inject the inner layer mixture into the upper space of the mold cavity until the mold cavity is completely filled. After completion, immediately lock and close the mold, and control the temperature of the upper part of the mold cavity to trigger the inner layer foaming reaction. Step S5: After locking the mold, maintain the temperature difference between the upper and lower parts of the mold cavity and keep it constant. Then, raise the overall mold temperature to allow the polymer ester system to complete cross-linking and curing, and fix the internal structure. Step S6: After curing, open the mold and remove the molding material, transfer it to a constant temperature and humidity ventilated environment for post-curing treatment, and finally obtain the finished polymer material for safety shoes.

[0021] Step S1 includes the following steps: Step S11: Nitrogen gas is introduced into the sealed stirred tank to replace the air inside the tank. After adding the polymer ester A material, the jacket heating device is turned on and the material temperature is raised to 45℃~48℃ in a uniform heating mode. During the heating process, the material liquid is continuously stirred at a low speed. At the same time, the vacuum dehydration system is turned on and dehydrated for 22min~25min under a vacuum of -0.085MPa~-0.09MPa. During the dehydration, samples are taken every 5min to test the water content of the material liquid. The vacuum system is turned off when the water content drops below 0.05%. Step S12: First, add 65% of the total mass of the hair hardening agent into the mixing tank, stir and disperse, then add 70% of the total mass of deionized water dropwise. Keep the material temperature constant at 45℃~48℃ throughout the process, maintain a slight positive pressure in the tank, and stir at a speed of 70r / min~75r / min for 9min~10min. After stirring, keep the stirring at a low speed and transfer the basic premix to the heat preservation standby state.

[0022] Step S2 includes the following steps: Step S21: After filtering the antistatic agent through a sieve, divide it into two groups with a mass ratio of 7:3. The first group is a high-concentration gradient component, and the second group is a low-concentration gradient component. Step S22: Take the high-concentration antistatic agent and the remaining 35% of the hair-styling agent and add them together into a dispersion container preheated to 45°C. Use an axial and radial combined stirring paddle to disperse at a stirring rate of 120 r / min for 6 min to 7 min to obtain a high-concentration antistatic dispersion. Step S23: Take the low concentration of antistatic agent and the remaining 30% of deionized water and add them to another set of preheated dispersion containers. Using the same stirring structure, disperse at a stirring rate of 120 r / min for 5 min to 6 min to obtain a low concentration of antistatic diluted solution. Step S24: Transfer the two dispersions to separate insulated storage tanks and seal them for storage. The storage tank jacket maintains the material temperature at 45°C. During storage, stir at low speed every 10 minutes, with each stirring session lasting 30 seconds.

[0023] Step S3 includes the following steps: Step S31: The basic premix is ​​quantitatively delivered to the primary material chamber of the injection molding machine using a metering pump. The amount of polyester-specific composite crosslinking curing agent specified in the formula is measured using a loss-in-weight scale and added to the material chamber. The double-layer stirring device built into the material chamber is turned on and mixed at a rate of 90 r / min for 60 s to 70 s to trigger the initial prepolymerization reaction of the system. During the prepolymerization process, the viscosity and temperature data of the liquid are collected in real time, and the temperature fluctuation is controlled within ±1℃. Step S32: When the viscosity of the liquid material rises to 1500 mPa·s to 1800 mPa·s as monitored online, the high-concentration antistatic dispersion is injected through the static mixing element in the distribution channel on the surface of the material chamber and rapidly mixed with the surface prepolymer liquid at a rate of 110 r / min for 30 s. Step S33: After mixing is completed, start the first-level injection program, using a rate curve of slow start-up, medium-speed mold filling, and slow finish-up. Inject the surface mixture liquid into the bottom area of ​​the shoe mold cavity at an injection pressure of 8MPa to 9MPa. Stop the injection after the liquid has filled 40% of the total thickness of the mold cavity and close the bottom inlet valve. Step S34: Open the heating channel of the bottom template of the mold cavity and keep the temperature of the bottom template of the mold cavity at 52℃~55℃ to trigger the micro-foaming reaction of the surface liquid.

[0024] Step S4 includes the following steps: Step S41: During the pause in injection, inject the low-concentration antistatic diluent into the main prepolymer liquid through the annular inlet on the side wall of the primary material chamber, maintain the material temperature at 48℃~50℃, and stir at a rate of 80r / min for 40s~50s using a double-layer reverse stirring paddle. Step S42: Collect the surface layer foaming thickness data in real time through the optical sensor on the side wall of the mold cavity. When the foaming thickness accounts for 35% of the total thickness of the mold cavity, start the secondary injection program and inject the inner layer mixture into the upper space of the mold cavity at an injection pressure of 6MPa to 7MPa in a gradually increasing manner until the liquid completely fills the mold cavity. Step S43: After injection, perform a graded mold-locking operation. First, close the mold with low pressure until the parting surface is in contact, then gradually increase the mold-locking force to the set value and lock it. Simultaneously, open the heating channel of the upper mold plate of the mold cavity to maintain the temperature of the upper mold plate of the mold cavity at 58℃~60℃.

[0025] Step S5 includes the following steps: Step S51: After mold clamping, the temperature of the upper and lower mold plates in the mold cavity is controlled by an independent temperature control unit to maintain a temperature difference of 8℃~10℃ between the upper and lower mold plates and maintain the constant temperature for 3min~3.5min; during this stage, the mold cavity remains in a sealed state and the clamping force remains constant. Step S52: Then, the mold cavity is heated in a stepped manner. First, it is heated to 60℃ and held for 2 minutes, then heated to 65℃~68℃ and held for 8 minutes~9 minutes to cure. After curing, the heating system is turned off and the mold cavity is kept in a sealed state to cool down naturally for 1 minute.

[0026] Step S6 includes the following steps: Step S61: After the curing cycle is completed, the mold cavity is slightly depressurized. After the pressure inside and outside the mold cavity is balanced, the mold is fully opened and the molded polymer material is ejected through the ejector pin mechanism inside the mold. Step S62: Transfer the molding material to the curing rack in the constant temperature and ventilation curing chamber and place it in a single layer with a gap between adjacent materials. Control the curing environment temperature to 40℃~42℃ and the relative humidity to 50%~55%. Use forced circulation ventilation and cure for 24 hours. Record the environmental temperature and humidity parameters every 2 hours during the curing period.

[0027] The polymer material used in the production and processing of safety shoes is prepared by foaming and curing a polymer ester matrix, foaming agent, curing agent, antistatic agent and deionized water. The antistatic agent forms a gradient distribution with continuously varying concentration along the thickness direction of the material, and the microporous structure inside the material exhibits a hierarchical distribution with a dense surface layer and a loose inner layer along the thickness direction.

[0028] The polymer materials used in the production and processing of safety shoes include the following components by weight: Polyester matrix 93.3-93.6%, foaming agent 2.0-2.1%, polyester-specific composite crosslinking curing agent 1.7-1.8%, antistatic agent 2.3-2.4%, deionized water 0.35-0.40%.

[0029] One specific application of this embodiment is: This embodiment provides a polymer material for the production and processing of safety shoes, specifically a gradient antistatic microporous polyester material for the outsole of safety shoes. Based on the amount used in a single batch production, the raw material composition is: 18 kg of crystalline saturated polyester resin matrix, 340 g of polyester-specific composite crosslinking curing agent, 400 g of hair-setting agent, 72 g of deionized water, and 450 g of antistatic agent. It is prepared through the following steps: Step S1: Preparation of basic premix Nitrogen gas was introduced into the sealed stirred tank to replace the air inside. 18 kg of crystalline saturated polyester resin matrix was then added. The jacketed heating device was turned on, and the material temperature was raised to 45°C at a uniform heating rate of 2°C / min. During the heating process, the liquid was continuously stirred at a low speed of 30 r / min. Simultaneously, the vacuum dehydration system was activated, and dehydration was performed for 22 min under a vacuum of -0.085 MPa. Samples were taken every 5 min during dehydration to check the water content of the liquid. The vacuum system was turned off once the water content of the liquid dropped to 0.048%.

[0030] First, add 260g of hair-strengthening agent to the mixing tank and stir and disperse for 3 minutes. Then, add 50.4g of deionized water dropwise. Keep the material temperature constant at 45℃ throughout the process and maintain a slight positive pressure of 0.02MPa in the tank. Stir at 70r / min for 9 minutes. After stirring, maintain a low stirring speed of 30r / min and transfer the basic premix to the heat preservation standby state.

[0031] Step S2: Preparation of graded antistatic dispersion After filtering 450g of antistatic agent through a 120-mesh sieve, it was divided into two groups with a mass ratio of 7:3. The first group of 315g was the high-concentration gradient component, and the second group of 135g was the low-concentration gradient component.

[0032] Take 315g of high-concentration antistatic agent and the remaining 140g of hair-straining agent and add them together to a dispersion container preheated to 45℃. Use an axial and radial combined stirring paddle to disperse at a stirring rate of 120r / min for 6min to obtain a uniform high-concentration antistatic dispersion.

[0033] Take 135g of low-concentration antistatic agent and the remaining 21.6g of deionized water and add them to another set of dispersion containers preheated to 45℃. Using the same stirring structure, disperse at a stirring rate of 120r / min for 5min to obtain a low-concentration antistatic diluted solution.

[0034] The two dispersions were transferred to separate insulated storage tanks and sealed for storage. The storage tank jacket maintained the material temperature at 45°C. During storage, the material was stirred at a low speed of 30 r / min every 10 minutes, with each stirring session lasting 30 seconds.

[0035] Step S3: Surface layer prepolymerization and primary injection The basic premix is ​​quantitatively delivered to the primary material chamber of the injection molding machine via a metering pump. 340g of polyester-specific composite crosslinking curing agent is measured using a loss-in-weight scale and added to the material chamber. The built-in double-layer stirring device in the material chamber is turned on and mixed at a rate of 90r / min for 60s to trigger the initial prepolymerization reaction of the system. During the prepolymerization process, the viscosity and temperature data of the liquid are collected in real time, and the temperature fluctuation is controlled within ±1℃.

[0036] When the viscosity of the liquid material is monitored online and rises to 1500 mPa·s, the high-concentration antistatic dispersion is injected through the static mixing element in the distribution channel on the surface of the material chamber, and rapidly mixed with the surface prepolymer liquid at a rate of 110 r / min for 30 s.

[0037] After mixing is complete, start the first-stage injection program, using a rate curve of slow start-up, medium-speed mold filling, and slow finish-up. Inject the surface mixture into the bottom area of ​​the shoe mold cavity at an injection pressure of 8MPa. Stop the injection after the mixture has filled 40% of the total thickness of the mold cavity and close the bottom inlet valve.

[0038] Open the heating channel of the bottom template of the mold cavity and maintain the temperature of the bottom template of the mold cavity at 52℃ to trigger the micro-foaming reaction of the surface liquid.

[0039] Step S4: Inner layer liquid blending and secondary injection During the pause in injection, a low-concentration antistatic diluent is injected into the main prepolymer liquid through the annular inlet on the side wall of the primary material chamber. The material temperature is maintained at 48°C, and the mixture is stirred for 40 seconds at a rate of 80 r / min using a double-layer reverse stirring paddle to ensure that the low-concentration antistatic agent is evenly dispersed in the main polyester system.

[0040] The surface layer foam thickness data is collected in real time by an optical sensor on the side wall of the mold cavity. When the foam thickness accounts for 35% of the total thickness of the mold cavity, the secondary injection program is started. The inner layer mixture is injected into the upper space of the mold cavity at an injection pressure of 6MPa in a gradually increasing manner until the mixture completely fills the mold cavity.

[0041] After injection, a graded clamping operation is performed. First, the mold is closed with low pressure until the parting surface is in contact. Then, the clamping force is gradually increased to the set value and locked. At the same time, the heating channel of the upper mold plate is opened to maintain the temperature of the upper mold plate at 58°C.

[0042] Step S5: In-mold gradient curing and shaping After mold clamping, the temperature of the upper and lower mold plates in the mold cavity is controlled by an independent temperature control unit to maintain a temperature difference of 8°C between the upper and lower mold plates and maintain the constant temperature for 3 minutes. During this stage, the mold cavity remains sealed and the clamping force remains constant.

[0043] The mold cavity was then heated in a stepped manner, first to 60°C and held for 2 minutes, then to 65°C and held for 8 minutes to cure. After curing, the heating system was turned off and the mold cavity was allowed to cool down naturally for 1 minute while remaining sealed.

[0044] Step S6: Curing after demolding After the curing cycle is completed, the mold cavity is slightly depressurized. Once the pressure inside and outside the mold cavity is balanced, the mold is fully opened, and the molded polymer material outer bottom is ejected through the ejector pin mechanism inside the mold.

[0045] The molded outsoles are transferred to a curing rack in a constant temperature and ventilation curing chamber and placed in a single layer, with a 5cm gap between adjacent outsoles. The curing environment is controlled at 40℃ and 50% relative humidity, with forced circulation ventilation, and the curing time is 24 hours. During the curing period, the ambient temperature and humidity parameters are recorded every 2 hours. After curing, a finished product of polymer material for safety shoe production is obtained, characterized by a gradient distribution of antistatic properties along the thickness direction and a microporous structure that is dense on the outside and sparse on the inside.

[0046] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing polymer materials used in the production and processing of safety shoes, characterized in that, Includes the following steps: Step S1: The polymer ester base raw material is preheated and vacuum dehydrated to reach the preset moisture content. Then, some foaming agent and some deionized water are added, and the mixture is stirred and dispersed at a constant temperature to obtain the base premix. The mixture is then sealed and kept warm for later use. Step S2: Divide the antistatic agent into two groups according to different mass ratios, and mix them with the remaining foaming agent and the remaining deionized water respectively. After stirring and dispersing, high-concentration antistatic dispersion and low-concentration antistatic dilution are prepared respectively. The two dispersions are stored separately in sealed and insulated conditions. Step S3: The basic premix is ​​fed into the injection molding machine cavity and a curing agent is added. The mixture triggers the prepolymerization reaction of the system. After the viscosity of the liquid rises to the preset range, the high-concentration antistatic dispersion is mixed into the surface liquid and mixed evenly. Then the surface mixed liquid is injected into the bottom area of ​​the shoe mold cavity. After the preset filling thickness is reached, the injection is paused and the temperature at the bottom of the mold cavity is controlled to trigger surface micro-foaming. Step S4: Inject the low-concentration antistatic diluent into the main prepolymer liquid in the material cavity, stir and disperse at a constant temperature, and after the surface foaming reaches the preset thickness, inject the inner layer mixture into the upper space of the mold cavity until the mold cavity is completely filled. After completion, immediately lock and close the mold, and control the temperature of the upper part of the mold cavity to trigger the inner layer foaming reaction. Step S5: After locking the mold, maintain the temperature difference between the upper and lower parts of the mold cavity and keep it constant. Then, raise the overall mold temperature to allow the polymer ester system to complete cross-linking and curing, and fix the internal structure. Step S6: After curing, open the mold and remove the molding material, transfer it to a constant temperature and humidity ventilated environment for post-curing treatment, and finally obtain the finished polymer material for safety shoes.

2. The method for preparing polymer materials for safety shoe manufacturing and processing according to claim 1, characterized in that: Step S1 includes the following steps: Step S11: Nitrogen gas is introduced into the sealed stirred tank to replace the air inside the tank. After adding the polymer ester A material, the jacket heating device is turned on and the material temperature is raised to 45℃~48℃ in a uniform heating mode. During the heating process, the material liquid is continuously stirred at a low speed. At the same time, the vacuum dehydration system is turned on and dehydrated for 22min~25min under a vacuum of -0.085MPa~-0.09MPa. During the dehydration, samples are taken every 5min to test the water content of the material liquid. The vacuum system is turned off when the water content drops below 0.05%. Step S12: First, add 65% of the total mass of the hair hardening agent into the mixing tank, stir and disperse, then add 70% of the total mass of deionized water dropwise. Keep the material temperature constant at 45℃~48℃ throughout the process, maintain a slight positive pressure in the tank, and stir at a speed of 70r / min~75r / min for 9min~10min. After stirring, keep the stirring at a low speed and transfer the basic premix to the heat preservation standby state.

3. The method for preparing polymer materials for safety shoe manufacturing and processing according to claim 1, characterized in that: Step S2 includes the following steps: Step S21: After filtering the antistatic agent through a sieve, divide it into two groups with a mass ratio of 7:

3. The first group is a high-concentration gradient component, and the second group is a low-concentration gradient component. Step S22: Take the high-concentration antistatic agent and the remaining 35% of the hair-styling agent and add them together into a dispersion container preheated to 45°C. Use an axial and radial combined stirring paddle to disperse at a stirring rate of 120 r / min for 6 min to 7 min to obtain a high-concentration antistatic dispersion. Step S23: Take the low concentration of antistatic agent and the remaining 30% of deionized water and add them to another set of preheated dispersion containers. Using the same stirring structure, disperse at a stirring rate of 120 r / min for 5 min to 6 min to obtain a low concentration of antistatic diluted solution. Step S24: Transfer the two dispersions to separate insulated storage tanks and seal them for storage. The storage tank jacket maintains the material temperature at 45°C. During storage, stir at low speed every 10 minutes, with each stirring session lasting 30 seconds.

4. The method for preparing polymer materials for safety shoe manufacturing and processing according to claim 3, characterized in that: Step S3 includes the following steps: Step S31: The basic premix is ​​quantitatively delivered to the primary material chamber of the injection molding machine using a metering pump. The amount of polyester-specific composite crosslinking curing agent specified in the formula is measured using a loss-in-weight scale and added to the material chamber. The double-layer stirring device built into the material chamber is turned on and mixed at a rate of 90 r / min for 60 s to 70 s to trigger the initial prepolymerization reaction of the system. During the prepolymerization process, the viscosity and temperature data of the liquid are collected in real time, and the temperature fluctuation is controlled within ±1℃. Step S32: When the viscosity of the liquid material rises to 1500 mPa·s to 1800 mPa·s as monitored online, the high-concentration antistatic dispersion is injected through the static mixing element in the distribution channel on the surface of the material chamber and rapidly mixed with the surface prepolymer liquid at a rate of 110 r / min for 30 s. Step S33: After mixing is completed, start the first-level injection program, using a rate curve of slow start-up, medium-speed mold filling, and slow finish-up. Inject the surface mixture liquid into the bottom area of ​​the shoe mold cavity at an injection pressure of 8MPa to 9MPa. Stop the injection after the liquid has filled 40% of the total thickness of the mold cavity and close the bottom inlet valve. Step S34: Open the heating channel of the bottom template of the mold cavity and keep the temperature of the bottom template of the mold cavity at 52℃~55℃ to trigger the micro-foaming reaction of the surface liquid.

5. The method for preparing polymer materials for safety shoe manufacturing and processing according to claim 4, characterized in that: Step S4 includes the following steps: Step S41: During the pause in injection, inject the low-concentration antistatic diluent into the main prepolymer liquid through the annular inlet on the side wall of the primary material chamber, maintain the material temperature at 48℃~50℃, and stir at a rate of 80r / min for 40s~50s using a double-layer reverse stirring paddle. Step S42: Collect the surface layer foaming thickness data in real time through the optical sensor on the side wall of the mold cavity. When the foaming thickness accounts for 35% of the total thickness of the mold cavity, start the secondary injection program and inject the inner layer mixture into the upper space of the mold cavity at an injection pressure of 6MPa to 7MPa in a gradually increasing manner until the liquid completely fills the mold cavity. Step S43: After injection, perform a graded mold-locking operation. First, close the mold with low pressure until the parting surface is in contact, then gradually increase the mold-locking force to the set value and lock it. Simultaneously, open the heating channel of the upper mold plate of the mold cavity to maintain the temperature of the upper mold plate of the mold cavity at 58℃~60℃.

6. The method for preparing polymer materials for safety shoe production and processing according to claim 2, characterized in that: Step S5 includes the following steps: Step S51: After mold clamping, the temperature of the upper and lower mold plates in the mold cavity is controlled by an independent temperature control unit to maintain a temperature difference of 8℃~10℃ between the upper and lower mold plates and maintain the constant temperature for 3min~3.5min; during this stage, the mold cavity remains in a sealed state and the clamping force remains constant. Step S52: Then, the mold cavity is heated in a stepped manner. First, it is heated to 60℃ and held for 2 minutes, then heated to 65℃~68℃ and held for 8 minutes~9 minutes to cure. After curing, the heating system is turned off and the mold cavity is kept in a sealed state to cool down naturally for 1 minute.

7. The method for preparing polymer materials for safety shoe manufacturing and processing according to claim 4, characterized in that: Step S6 includes the following steps: Step S61: After the curing cycle is completed, the mold cavity is slightly depressurized. After the pressure inside and outside the mold cavity is balanced, the mold is fully opened and the molded polymer material is ejected through the ejector pin mechanism inside the mold. Step S62: Transfer the molding material to the curing rack in the constant temperature and ventilation curing chamber and place it in a single layer with a gap between adjacent materials. Control the curing environment temperature to 40℃~42℃ and the relative humidity to 50%~55%. Use forced circulation ventilation and cure for 24 hours. Record the environmental temperature and humidity parameters every 2 hours during the curing period.

8. A polymer material used in the production and processing of safety shoes, characterized in that, It is prepared by foaming and curing a polymer ester matrix, a foaming agent, a curing agent, an antistatic agent and deionized water; the antistatic agent forms a gradient distribution with a continuously varying concentration along the thickness direction of the material, and the microporous structure inside the material exhibits a hierarchical distribution with a dense surface layer and a loose inner layer along the thickness direction.

9. The polymer material for manufacturing and processing safety shoes according to claim 8, characterized in that, The following components are included in parts by weight: Polyester matrix 93.3-93.6%, foaming agent 2.0-2.1%, polyester-specific composite crosslinking curing agent 1.7-1.8%, antistatic agent 2.3-2.4%, deionized water 0.35-0.40%.

Images