Lightweight safety toe cap and preparation method thereof

Abstract

The invention discloses a lightweight safety toe cap and a preparation method thereof. The light-weight safety toe cap comprises an outer shell and an inner core reinforcing structure, the outer shell is connected to the outer wall of the inner core reinforcing structure, the outer shell is made of a thermoplastic composite material containing 60-70 wt% of reinforced continuous fibers, the inner core reinforcing structure is made of a thermoplastic nylon injection molding material containing 30-40 wt% of reinforced long fibers, and the outer shell is made of a thermoplastic composite material containing 60-70 wt% of reinforced continuous fibers. The inner core reinforcing structure is of a three-dimensional honeycomb structure. The lightweight safety toe cap not only can meet the high-standard safety protection requirement, but also can realize extreme lightweight.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of labor protection articles and personal protective equipment, in particular to a light-weight safety toe and a preparation method thereof. BACKGROUND

[0002] Safety shoes are essential labor protection articles for employees in many industries. One of the core protective components of safety shoes is the safety toe located at the front of the safety shoes, which is used to protect the toes of the wearer from being injured by falling objects and other impacts. The safety toe of the traditional technology is mainly made of steel materials such as alloy steel or aluminum alloy. Although the safety toe made of such materials has reliable protection performance, it has the disadvantages of heavy weight, usually more than 100g, heavy to wear, easy to corrode, poor thermal insulation, and cold in winter and hot in summer.

[0003] To reduce the weight of safety shoes, the traditional technology has appeared to use engineering plastics or short fiber reinforced composite materials to prepare safety toes by injection molding. The safety toe made of such materials has a lighter weight, but its impact resistance, compression resistance and toughness often cannot meet the high standard safety specifications (such as GBT20991-2007, GB21148-2020, etc.) at the same time, especially when dealing with high intensity impact, it is easy to cause brittle fracture or excessive deformation, resulting in protection failure. In addition, the traditional technology also has a safety toe made of continuous fiber reinforced thermosetting composite materials (such as carbon fiber, glass fiber) by lamination and hot pressing process; the safety toe made of such materials has high strength, but usually uses the process of laying up pre-preg and molding, and its internal structure is solid or simple sandwich structure, which brings difficulties for further weight reduction, and the process is complicated, the production efficiency is low, cannot realize automation, and the cost is high. SUMMARY

[0004] Therefore, it is necessary to provide a light-weight safety toe which can meet the high standard safety protection requirements and achieve extreme light weight, and a preparation method thereof.

[0005] An embodiment of the present application provides a light-weight safety toe.

[0006] A light-weight safety toe includes an outer shell and an inner core reinforcing structure, the outer shell is connected to the outer wall of the inner core reinforcing structure, the outer shell is made of a thermoplastic composite material containing 60wt%-70wt% reinforcing continuous fibers, the inner core reinforcing structure is made of a thermoplastic injection molding material containing 30wt%-50wt% reinforcing long fibers, and the inner core reinforcing structure has a three-dimensional honeycomb structure.

[0007] In some embodiments, the matrix of the thermoplastic composite material includes one or more of nylon, nylon 6, nylon 66, PA12, polypropylene, polycarbonate, polyether ether ketone, and polyphenylene sulfide.

[0008] In some embodiments, the matrix of the thermoplastic injection molding material comprises one or more of nylon, nylon 6, nylon 66, PA12, polypropylene, polycarbonate, polyether ether ketone, and polyphenylene sulfide.

[0009] In some embodiments, the reinforcing continuous fibers comprise one or more of glass fibers, carbon fibers, basalt fibers, and Kevlar fibers.

[0010] In some embodiments, the reinforcing continuous fibers are in the form of unidirectional tapes, fabrics, or randomly oriented mats.

[0011] In some embodiments, the reinforcing long fibers have a length of 10 mm to 20 mm.

[0012] In some embodiments, the outer shell is integrally connected to the inner core reinforcement structure.

[0013] In some embodiments, the three-dimensional honeycomb structure occupies 40% to 70% of the total area of the inner core reinforcement structure.

[0014] In some embodiments, the honeycomb shape in the three-dimensional honeycomb structure comprises one or more of hexagonal honeycombs, square honeycombs, and circular honeycombs.

[0015] In some embodiments, the shape of the inner core reinforcement structure is adapted to the shape of the inner wall of the outer shell.

[0016] In some embodiments, the thickness of the inner core reinforcement structure is 1 mm to 4 mm.

[0017] In some embodiments, the thickness of the outer shell is 2 mm to 6 mm.

[0018] In some embodiments, the total weight of the lightweight safety toe is < 50 g.

[0019] An embodiment of the present application further provides a preparation method of a lightweight safety toe.

[0020] A preparation method of a lightweight safety toe, comprising the following steps:

[0021] cutting the fiber sheet into a preset shape;

[0022] laying the cut fiber sheet in a preset direction and melting it to a softened state to form a blank;

[0023] transferring the blank into a mold;

[0024] controlling the mold to close and pressurize the blank to form an outer shell of a preset shape.

[0025] and, maintaining the mold pressure, injecting molten thermoplastic nylon injection material into the cavity between the inner wall of the outer shell and the mold through the injection port on the mold to form an inner core reinforcing structure connected with the outer shell, the thermoplastic nylon injection material being blocked by the core on the inner wall of the mold to form a three-dimensional honeycomb structure.

[0026] In some embodiments, the fiber sheet is formed by reinforcing continuous fibers pre-impregnated with a thermoplastic resin, and the content of the reinforcing continuous fibers in the fiber sheet is 60wt%-70wt%.

[0027] In some embodiments, an infrared heating device is used to bake the fiber sheet of the layup to a molten softened state to form a blank.

[0028] In some embodiments, the temperature when molten to a softened state is 250℃-400℃.

[0029] In some embodiments, a mechanical hand is used to transfer the blank into the mold.

[0030] In some embodiments, the pressure of the mold closing and pressing the blank is controlled to be 10MPa-20MPa.

[0031] In some embodiments, the thermoplastic injection material contains 30wt%-50wt% reinforcing long fibers.

[0032] In some embodiments, the length of the reinforcing long fibers is 10mm-20mm.

[0033] In some embodiments, the method for preparing a lightweight safety shoe head further comprises a cooling demolding step: demolding after cooling to 60℃-150℃ to obtain a safety shoe head.

[0034] The above lightweight safety shoe head can not only meet high-standard safety protection requirements, but also achieve extreme lightweight, and is suitable for efficient and low-cost industrial production. The lightweight safety shoe head of the present application realizes the best balance between protection performance and lightweight through unique material combination and structure design, combined with innovative mold pressing and injection molding integrated process.

[0035] In the present application, the specific combination of "continuous fiber thermoplastic outer shell + long fiber thermoplastic injection molded inner core reinforcing structure", the fiber content ratio in the outer shell and the inner core reinforcing structure, and the compatibility of the two matrix resins, improves the composite performance of the safety toe; through the integrated composite structure design of "continuous fiber dense outer shell + long fiber honeycomb inner core reinforcing structure", the structural performance of the safety toe is improved; through "direct injection molding after molding, completed in a mold, once the mold cycle", the processing technology is simplified, and the perfect combination of materials and structure is realized. Finally, the safety toe with a weight of less than 50g is realized, which not only realizes lightweight, but also meets the harsh safety standards.

[0036] In summary, the lightweight safety toe of the present application has at least the following beneficial effects:

[0037] (1) Extremely light weight. The weight of the safety toe is less than 50g, which is much lighter than the steel toe (more than 100g) in the traditional technology, and even lighter than the engineering plastic or ordinary composite material toe. This can significantly reduce the fatigue of the wearer, greatly reduce the burden on the feet when walking or working for a long time, effectively improve the work efficiency and comfort, and the light toe makes the foot movement more flexible, especially suitable for workers who need to climb and move frequently, and improves flexibility.

[0038] (2) Super protection. The outer shell forms a "high-strength framework", and the continuous fiber provides unparalleled overall rigidity and bending resistance, which can effectively resist the invasion of external impact objects and prevent being pierced or torn. The inner core reinforcing structure is a honeycomb structure, which plays the role of "energy absorption box". When impacted, the inner core reinforcing structure will efficiently disperse and absorb the huge impact energy through orderly deformation, avoiding damage caused by concentrated force. The protection performance not only meets but also exceeds the most stringent international safety standards (such as EN ISO 20345), providing top-level life safety protection for users.

[0039] (3) High toughness and fatigue resistance. The thermoplastic resin matrix itself has excellent toughness, and after being combined with glass fiber, its impact toughness is much higher than that of brittle thermosetting resin, and it is not prone to sudden brittle fracture. The safety toe has higher durability and longer service life, and the performance decay after multiple minor impacts is much smaller than that of other materials.

[0040] (4) One-piece molding, firm structure without weak points. The outer shell and the inner core reinforcing structure are "welded" into one body by the molten thermoplastic resin matrix in the mold, the interface bonding strength is extremely high, there is no risk of adhesive aging and delamination, and the stress concentration problem caused by screw connection is also avoided. The safety toe product has excellent structural integrity, fundamentally solves the common problem of delamination between composite material layers, and greatly improves reliability.

[0041] (5) The production process is efficient and the cost is controllable. The safety toe processing process of the application includes "molding-injection", and all steps are completed in one production cycle of about 1-2 minutes, realizing highly automated and large-scale production. The production efficiency is much faster than the traditional technology of manual layering and long-term curing. Although the grade of raw materials is high, the cost of a single piece is effectively controlled, the comprehensive cost is low, and it has strong market competitiveness.

[0042] (6) Chemical corrosion resistance and rust prevention. The safety toe of the application has a full composite material structure, which has natural resistance to water, salt spray, most chemicals and solvents. It is especially suitable for humid and corrosive environments such as chemical industry, ocean, food processing, etc., and its service life is much longer than that of metal toe caps.

[0043] (7) Thermal and electrical insulation. The composite material used in the safety toe of the application is a poor conductor of heat and electricity, which can prevent the feet from being cold in winter and hot in summer, and provide additional safety protection for workers in the electrical industry.

[0044] (8) High design freedom. The one-piece molding process of the safety toe of the application can manufacture very complex internal honeycomb structures and external streamlined curves, which is difficult to achieve by traditional technology of metal stamping, and can design a more ergonomic internal space of the toe, further improving the wearing comfort. BRIEF DESCRIPTION OF DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0046] In order to more completely understand the application and its beneficial effects, the following will be described with reference to the drawings. In the following description, the same reference numbers represent the same parts.

[0047] Figure 1 The schematic diagram of the light weight safety toe according to an embodiment of the application;

[0048] Figure 2 The schematic diagram of the outer shell of the light weight safety toe according to an embodiment of the application;

[0049] Figure 3 The schematic diagram of the inner core reinforcing structure of the light weight safety toe according to an embodiment of the application;

[0050] Figure 4Preparation process flowchart of the light-weight safety toe according to an embodiment of the present application;

[0051] Figure 5 Pressure resistance simulation result diagram of the light-weight safety toe according to an embodiment of the present application;

[0052] Figure 6 Impact resistance simulation result diagram of the light-weight safety toe according to an embodiment of the present application.

[0053] Explanation of reference signs

[0054] 10, light-weight safety toe; 100, outer shell; 200, inner core reinforcing structure; 201, three-dimensional honeycomb structure. DETAILED DESCRIPTION

[0055] In order to make the above objectives, features and advantages of the present application more apparent, specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, the present application can be practiced in a number of different ways beyond the specific embodiments described and it is to be understood that the present application is not limited to the specific embodiments described below.

[0056] In the description of the present application, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application.

[0057] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements, unless otherwise explicitly limited. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0058] In the present application, unless specifically stated and limited otherwise, a first feature is "on" or "under" a second feature can mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature "over", "above" and "on top of" the second feature can mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is horizontally higher than the second feature. The first feature "under", "below" and "underneath" the second feature can mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is horizontally lower than the second feature.

[0059] In the description of the present application, the meaning of "several" is more than one, the meaning of "multiple" is more than two, greater than, less than, more than, etc. are understood as not including the number, above, below, etc. are understood as including the number. If it is described that the first, second is only used for the purpose of distinguishing technical features, it cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or implicitly indicating the sequence of indicated technical features.

[0060] In the present application, "optionally", "optional" and "optional" mean that it can or can not be, that is, it means to select from two parallel schemes of "have" or "have". If there are multiple "options" in a technical solution, unless otherwise specified, and there is no contradiction or mutual restriction, each "option" is independent of each other. In the present application, "optionally contains", "optionally contains" and the like are described as "contains or does not contain".

[0061] In the present application, if there is no contrary statement, the sum of the parts of each component in the composition can be 100 parts by weight. If not specifically pointed out, the basis of the percentage (including weight percentage) of the present application is the total weight of the composition, and "wt%" herein means mass percentage.

[0062] In the present application, unless otherwise specified, each reaction step can be carried out in the order described herein, or can not be carried out in the order described herein. For example, each reaction step can contain other steps, and the order of the reaction steps can also be appropriately exchanged. This can be determined by the skilled person according to conventional knowledge and experience. Preferably, the reaction method herein is carried out in sequence.

[0063] In this application, when numerical intervals (i.e., numerical ranges) are mentioned, unless otherwise specified, the distribution of selectable numerical values ​​within the numerical interval is considered continuous, and includes the two endpoints of the numerical interval (i.e., the minimum and maximum values), as well as every numerical value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that numerical interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints, which is equivalent to directly listing every integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical ranges disclosed in this application should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, percentage, ratio, etc. The term "numerical interval" can be broadly included to include percentage intervals, ratio intervals, proportion intervals, etc.

[0064] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0065] This application provides a lightweight safety toe cap to address at least one of the following technical problems of conventional safety toe caps: (1) Safety toe caps made of steel, such as alloy steel or aluminum alloy, are heavy, usually exceeding 100g, and have disadvantages such as being bulky to wear, prone to corrosion, poor heat insulation, and cold in winter and hot in summer. (2) Safety toe caps made of engineering plastics or short fiber reinforced composite materials through injection molding are difficult to meet high-standard safety specifications at the same time. When subjected to high-intensity impacts, they are prone to brittle fracture or excessive deformation, leading to protective failure. (3) Safety toe caps made of continuous fiber reinforced thermosetting composite materials such as carbon fiber and glass fiber through molding, vacuum bagging, and other processes are cumbersome, have low production efficiency, cannot be automated, and are costly. The lightweight safety toe cap will be described below with reference to the accompanying drawings.

[0066] The lightweight safety toe cap 10 provided in one embodiment of this application is exemplary; please refer to [link to example]. Figure 1 As shown, Figure 1 This is a schematic diagram of the lightweight safety toe cap 10 provided in one embodiment of this application. The lightweight safety toe cap 10 of this application can meet high-standard safety protection requirements while achieving the goal of extreme lightweighting.

[0067] To more clearly illustrate the structure of the lightweight safety toe cap 10, the following description of the lightweight safety toe cap 10 will be provided in conjunction with the accompanying drawings.

[0068] For example, please refer to Figure 1 As shown, a lightweight safety toe cap 10 includes an outer shell 100 and an inner core reinforcement structure 200. The outer shell 100 is connected to the outer wall of the inner core reinforcement structure 200. The outer shell 100 is made of a thermoplastic composite material containing 60wt%~70wt% reinforcing continuous fibers. The inner core reinforcement structure 200 is made of a thermoplastic injection molding compound containing 30wt%~50wt% reinforcing long fibers. The inner core reinforcement structure 200 has a three-dimensional honeycomb structure 201.

[0069] The aforementioned lightweight safety toe cap 10 meets high safety protection requirements while achieving extreme lightweight design, and is suitable for efficient, low-cost industrial production. The lightweight safety toe cap 10 of this application achieves the optimal balance between protective performance and lightweight design through a unique material combination and structural design, combined with an innovative compression molding process.

[0070] In some embodiments, the matrix of the thermoplastic composite includes one or more of nylon, nylon 6, nylon 66, PA12, polypropylene (PP), polycarbonate (PC), polyetheretherketone (PEEK), and polyphenylene sulfide (PPS).

[0071] In some embodiments, the matrix of the thermoplastic injection molding compound includes one or more of nylon, nylon 6, nylon 66, PA12, polypropylene (PP), polycarbonate (PC), polyetheretherketone (PEEK), and polyphenylene sulfide (PPS).

[0072] In some embodiments, the reinforcing continuous fiber includes one or more of glass fiber, carbon fiber, basalt fiber, and Kevlar fiber.

[0073] In this application, glass fiber is the most widely used and cost-effective reinforcing fiber. It is made from molten glass and has high strength, good insulation, excellent corrosion resistance, and is non-flammable and inexpensive. Its greatest advantage is its balanced overall performance and low production cost.

[0074] Carbon fiber, hailed as "black gold," is a representative of high-performance composite materials. It is made from organic fibers through high-temperature carbonization and is essentially graphite microcrystals. Its most outstanding advantages are its extremely high specific strength (strength to density) and specific modulus (stiffness to density), meaning it is both as light as a feather and as strong as steel. Simultaneously, it exhibits fatigue resistance, a low coefficient of thermal expansion, and dimensional stability.

[0075] Basalt fiber is a "green" fiber derived from natural volcanic rock. It is made by directly drawing basalt rock after melting at high temperature, and the production process is environmentally friendly. Its advantages are excellent temperature resistance (it can work in the range of -260℃ to 700℃), good chemical corrosion resistance (especially stronger than glass fiber in alkali resistance), and inexhaustible raw materials.

[0076] Kevlar fiber is an organic synthetic high-performance aramid fiber. Its core advantage is not the extremely high modulus, but the unparalleled toughness, impact resistance and shear resistance. It has extremely high specific strength, and can absorb energy through large plastic deformation when impacted, rather than brittle fracture. Therefore, it is known as "bulletproof fiber", and is an ideal material for personal protective equipment (such as body armor, helmets), cut-resistant gloves, and high-impact parts (such as ship armor).

[0077] In some embodiments, the reinforcing continuous fibers are in the form of unidirectional tapes, fabrics, or randomly oriented mats.

[0078] In some embodiments, the length of the reinforcing long fibers is 10mm-20mm. For example, the length of the reinforcing long fibers includes but is not limited to: 10mm, 12mm, 15mm, 17mm, 18mm, 20mm, or a range between any two of the foregoing.

[0079] In some embodiments, the outer shell 100 is connected to the inner core reinforcement structure 200 in an integrated structure. The connection of the outer shell 100 to the inner core reinforcement structure 200 in an integrated structure can improve the composite strength of the lightweight safety shoe head 10 and improve safety performance.

[0080] In some embodiments, the area of the three-dimensional honeycomb structure 201 accounts for 40%-70% of the total area of the inner core reinforcement structure 200. For example, the area of the three-dimensional honeycomb structure 201 accounts for the total area of the inner core reinforcement structure 200 includes but is not limited to: 40%, 45%, 50%, 55%, 60%, 65%, 70%, or a range between any two of the foregoing.

[0081] In some embodiments, the honeycomb shape in the three-dimensional honeycomb structure 201 includes one or more of hexagonal honeycomb, square honeycomb, and circular honeycomb, which functions to disperse and absorb impact energy and prevent local collapse.

[0082] In some embodiments, the shape of the inner core reinforcement structure 200 is adapted to the shape of the inner wall of the outer shell 100.

[0083] In some embodiments, the thickness of the inner core reinforcing structure 200 is 1 mm to 4 mm. For example, the thickness of the inner core reinforcing structure 200 includes, but is not limited to, 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, or a range between any two of the aforementioned values.

[0084] In some embodiments, the thickness of the outer shell 100 is 2 mm to 6 mm. For example, the thickness of the outer shell 100 includes, but is not limited to, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, or a range between any two of the aforementioned values.

[0085] In some embodiments, the total weight of the light-weight safety toe 10 is < 50 g.

[0086] The present application also provides a method for manufacturing a light-weight safety toe 10.

[0087] Referring to Figure 6 shown, Figure 6 The present application also provides a method for manufacturing a light-weight safety toe 10.

[0088] S10, sheet cutting: cutting the fiber sheet into a predetermined shape.

[0089] S20, baking heating: laying the cut fiber sheet in a predetermined direction and melting it to a softened state to form a blank.

[0090] S30, blank transfer: transferring the blank to a mold.

[0091] S40, mold closing and pressing: controlling the mold to close and press the blank to form an outer shell 100 with a predetermined shape.

[0092] S50, injection molding pressure maintaining: maintaining the mold pressure, injecting molten thermoplastic injection material into the cavity between the inner wall of the outer shell 100 and the mold through the injection port on the mold to form an inner core reinforcing structure 200 connected to the outer shell 100, and the thermoplastic injection material is blocked by the core on the inner wall of the mold to form a three-dimensional honeycomb structure 201.

[0093] In some embodiments, the fiber sheet is formed by impregnating a reinforcing continuous fiber with a thermoplastic resin. The content of the reinforcing continuous fiber in the fiber sheet is 60 wt% to 70 wt%. For example, the content of the reinforcing fiber in the fiber sheet includes, but is not limited to, 60 wt%, 61 wt%, 62 wt%, 63 wt%, 64 wt%, 65 wt%, 66 wt%, 67 wt%, 68 wt%, 69 wt%, 70 wt%, or a range between any two of the aforementioned values.

[0094] In some embodiments, the fiber sheets of the lay-up are melted to a softened state using an infrared heating device to form a preform.

[0095] In some embodiments, the temperature at which the fiber sheets of the lay-up are melted to a softened state is between 250 °C and 400 °C. For example, the temperature at which the fiber sheets of the lay-up are melted to a softened state includes, but is not limited to, 250 °C, 255 °C, 260 °C, 265 °C, 270 °C, 275 °C, 280 °C, 285 °C, 290 °C, 295 °C, 300 °C, 305 °C, 310 °C, 315 °C, 320 °C, 325 °C, 330 °C, 335 °C, 340 °C, 345 °C, 350 °C, 355 °C, 360 °C, 365 °C, 370 °C, 375 °C, 380 °C, 385 °C, 390 °C, 395 °C, 400 °C, or a range between any two of the foregoing.

[0096] In some embodiments, the preform is transferred into the mold using a robot.

[0097] In some embodiments, the pressure at which the mold is closed to pressurize the preform is between 10 MPa and 20 MPa. For example, the pressure at which the mold is closed to pressurize the preform includes, but is not limited to, 10 MPa, 11 MPa, 12 MPa, 13 MPa, 14 MPa, 15 MPa, 16 MPa, 17 MPa, 18 MPa, 19 MPa, 2 MPa, or a range between any two of the foregoing.

[0098] In some embodiments, the thermoplastic injection molding material contains between 30 wt% and 50 wt% of the reinforcing long fibers.

[0099] In some embodiments, the reinforcing long fibers have a length between 10 mm and 20 mm. For example, the reinforcing long fibers have a length includes, but is not limited to, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, or a range between any two of the foregoing.

[0100] In some embodiments, the injection pressure at which the molten thermoplastic injection molding material is injected through the injection port of the mold is between 80 MPa and 100 MPa. For example, the injection pressure at which the molten thermoplastic injection molding material is injected through the injection port of the mold includes, but is not limited to, 80 MPa, 82 MPa, 85 MPa, 88 MPa, 90 MPa, 92 MPa, 95 MPa, 97 MPa, 99 MPa, 100 MPa, or a range between any two of the foregoing.

[0101] In some embodiments, the method for preparing the lightweight safety toe 10 further comprises a step of cooling demolding: after cooling to 60℃~150℃, the mold is opened to obtain the safety toe.

[0102] The safety toe prepared by the method for preparing the lightweight safety toe 10 of the present application has an outer shape conforming to the shape of the human toe part. The outer shell 100 is formed by molding a thermoplastic prepreg sheet material containing 60wt%~70wt% reinforcing continuous fibers. The prepreg sheet material is cut and laminated before molding to ensure that the fiber direction is staggered between different layers to balance the mechanical properties in each direction. After the outer shell 100 is formed by molding, the mold remains closed, and the molten thermoplastic injection material containing 30wt%~50wt% reinforcing long fibers is injected into the mold. During the flow process, the molten thermoplastic injection material is blocked by the core designed inside the mold, and finally fills and forms the honeycomb-shaped inner core reinforcement structure 200 as shown in Figure 3 .

[0103] In the present application, the resin matrix of the thermoplastic injection material and the resin matrix of the outer shell 100 prepreg are the same material, and the interface between the outer shell 100 and the inner core reinforcement structure 200 is fused and bonded to form a firm and integral structure as a whole. The entire molding cycle is about 60s~90s. After the safety toe is molded, the total weight is 45g~50g after trimming. According to the impact resistance test (200J energy) and pressure resistance test (15kN) in the laboratory according to GBT20991-2007 standard, the minimum gap in the toe after the test meets the required value of GB21148-2020 standard, and the performance is excellent, fully meeting the safety standards of the highest protection level.

[0104] Example 1

[0105] The present embodiment provides a method for preparing a lightweight safety toe 10.

[0106] Material preparation: The outer shell 100 is prepared from 8 layers of thermoplastic nylon composite material containing 60wt% continuous glass fiber fiber sheet (unidirectional tape or fabric). The inner core reinforcement structure 200 is prepared from thermoplastic nylon injection material containing 40wt% reinforcing long fibers (fiber length 12mm).

[0107] Mold and equipment: A dedicated molding and injection integrated molding mold is used, which has a core that can form a honeycomb structure. The equipment is a hydraulic machine with molding and injection functions and a molding and injection integrated molding equipment with a matching injection unit.

[0108] A method for preparing a lightweight safety toe 10, comprising the following steps:

[0109] S100, Sheet Cutting: The fiber sheet is cut into a predetermined shape. The fiber sheet is formed by pre-impregnating nylon resin with reinforcing continuous glass fibers, and the content of the reinforcing continuous fibers in the fiber sheet is 60 wt%. The matrix of the nylon resin is PA6.

[0110] S200, Baking and Heating: The cut fiber sheets are laid in a preset direction and heated to 250°C using an infrared heating device to bake the fiber sheets until they melt and soften to form a blank.

[0111] S300, Blank Transfer: Use a robotic arm to transfer the blank into the mold cavity.

[0112] S400, Mold Closure and Pressing: Control the mold to close and pressurize the blank at a pressure of 10MPa to form an outer shell 100 that conforms to the shape of the human toe.

[0113] S500, Injection Pressing: Maintain a mold pressure of 10 MPa, immediately start the injection unit, set the injection pressure to 80 MPa, and inject molten thermoplastic nylon through the injection port on the mold into the cavity between the inner wall of the outer shell 100 and the mold, forming an inner core reinforcement structure 200 connected to the outer shell 100. The thermoplastic nylon contains 40 wt% reinforcing long fibers. The matrix of the thermoplastic nylon is PA6.

[0114] S600, Cooling and Demolding: After holding the pressure and cooling for 30 seconds to about 100°C, open the mold to obtain the safety toe.

[0115] The lightweight safety shoe toe 10 prepared in this embodiment includes an outer shell 100 and an inner core reinforcing structure 200. The outer shell 100 is connected to the outer wall of the inner core reinforcing structure 200. The inner core reinforcing structure 200 has a three-dimensional honeycomb structure 201. The area of ​​the three-dimensional honeycomb structure 201 occupies 60% of the total area of ​​the inner core reinforcing structure 200. The honeycomb shape in the three-dimensional honeycomb structure 201 includes hexagonal honeycombs.

[0116] S700, Post-processing and Testing: The removed safety shoe toe caps were trimmed. The toe caps were weighed and found to be 47g.

[0117] See Figure 4 , Figure 5 As shown, Figure 4 This is a schematic diagram of the pressure resistance simulation results of the lightweight safety toe cap 10 in Example 1. Figure 5 This is a schematic diagram of the impact resistance simulation results of the lightweight safety toe cap 10 in Example 1. Figure 4 It can be seen that the maximum displacement of the protective cap head is 5.29mm, and the remaining internal space is 35.35mm, which meets the requirements. Figure 5It can be seen that the maximum displacement of the protective package head is 24.08 mm, and the remaining space inside is 15.92 mm, which meets the requirements. According to the GBT20991-2007 standard, after the 200J drop hammer impact test, the minimum gap in the toe cavity is greater than the standard requirement of 13.5 mm; after the 15kN static pressure test, the deformation is also within the allowable range, proving that it fully meets the safety standards.

[0118] Comparative Example 1

[0119] The present comparative example provides a preparation method of a lightweight safety toe.

[0120] The preparation method of the lightweight safety toe of the present comparative example is basically the same as that of Example 1, except that in the present comparative example, the content of the continuous glass fiber in the fiber sheet in the S100 step is 50wt%, i.e., the content of the continuous glass fiber in the fiber sheet is less.

[0121] According to the GBT20991-2007 standard, after the 200J drop hammer impact test, the minimum gap in the toe cavity is 10.68 mm, which is less than the standard requirement of 13.5 mm; after the 15kN static pressure test, the minimum gap in the toe cavity is 11.53 mm, which is less than the standard requirement of 13.5 mm, proving that it does not meet the safety standards.

[0122] Comparative Example 2

[0123] The present comparative example provides a preparation method of a lightweight safety toe.

[0124] The preparation method of the lightweight safety toe of the present comparative example is basically the same as that of Example 1, except that in the present comparative example, the content of the long glass fiber in the thermoplastic nylon injection material in the S500 step is 25wt%, i.e., the content of the long glass fiber in the thermoplastic nylon injection material is less.

[0125] According to the GBT20991-2007 standard, after the 200J drop hammer impact test, the minimum gap in the toe cavity is 10.97 mm, which is less than the standard requirement of 13.5 mm; after the 15kN static pressure test, the minimum gap in the toe cavity is 12.03 mm, which is less than the standard requirement of 13.5 mm, proving that it does not meet the safety standards.

[0126] Comparative Example 3

[0127] The present comparative example provides a preparation method of a lightweight safety toe.

[0128] The preparation method of the lightweight safety toe of the present comparative example is different from that of Example 1, except that in the present comparative example, the thermoplastic nylon injection material containing 40wt% long glass fiber is used, i.e., the use of continuous glass fiber sheet is cancelled.

[0129] According to the test of GBT20991-2007 standard: after 200J drop hammer impact test, the toe cap is broken and fractured; after 15kN static pressure test, the toe cap is broken and fractured, which proves that it does not meet the safety standard.

[0130] Comparative Example 4

[0131] The present comparative example provides a preparation method of a light-weight safety toe cap.

[0132] The preparation method of the light-weight safety toe cap of the present comparative example is different from that of Example 1 in that, in the present comparative example, the thermoplastic nylon injection material contains 40wt% long carbon fibers, that is, the use of continuous glass fiber sheet is cancelled, and the thermoplastic nylon injection material containing 40wt% long glass fibers is replaced by a thermoplastic nylon injection material containing 40wt% long carbon fibers.

[0133] According to the test of GBT20991-2007 standard: after 200J drop hammer impact test, the toe cap is cracked and light leaks; after 15kN static pressure test, the toe cap is cracked and light leaks, which proves that it does not meet the safety standard.

[0134] Comparative Example 5

[0135] The present comparative example provides a preparation method of a light-weight safety toe cap.

[0136] The preparation method of the light-weight safety toe cap of the present comparative example is different from that of Example 1 in that, in the present comparative example, the thermoplastic nylon injection material contains 50wt% long carbon fibers, that is, the use of continuous glass fiber sheet is cancelled, and the thermoplastic nylon injection material containing 40wt% long glass fibers is replaced by a thermoplastic nylon injection material containing 50wt% long carbon fibers.

[0137] According to the test of GBT20991-2007 standard: after 200J drop hammer impact test, the toe cap is cracked and light leaks; after 15kN static pressure test, the toe cap is cracked and light leaks, which proves that it does not meet the safety standard.

[0138] In the present application, the specific combination of the continuous fiber thermoplastic outer shell 100 and the long fiber thermoplastic injection-molded inner core reinforcing structure 200, the fiber content ratio of the outer shell 100 and the inner core reinforcing structure 200, such as 60wt% of reinforced continuous fibers in the thermoplastic composite material, 40wt% of reinforced long fibers in the thermoplastic nylon injection material, and the compatibility of the thermoplastic nylon matrix resins of the outer shell 100 and the inner core reinforcing structure 200, improve the composite performance of the safety toe cap; through the integrated composite structure design of the "continuous fiber dense outer shell 100 and long fiber honeycomb inner core reinforcing structure 200", the structural performance of the safety toe cap is improved; through the "direct injection after molding, completed in a mold, once a mold cycle" integrated molding process, the processing technology is simplified, and the perfect combination of materials and structure is realized. The final realization of the safety toe cap <50g of ultra-light weight, while meeting the harsh safety standards on the basis of light weight.

[0139] In summary, the light-weight safety toe cap 10 of the present application has at least the following beneficial effects:

[0140] (1) Extremely light weight. The weight of the safety toe cap is less than 50g, which is much lighter than the steel toe cap (>100g) in the traditional technology, and even lighter than the engineering plastic or ordinary composite material toe cap. This can significantly reduce the fatigue of the wearer, greatly reduce the burden on the feet when walking or working for a long time, effectively improve the work efficiency and comfort, and the light toe cap makes the foot movement more flexible, especially suitable for workers who need to climb and move frequently, and improves flexibility.

[0141] (2) Super protection. The outer shell 100 forms a "high-strength framework", and the continuous fibers provide unparalleled overall rigidity and bending resistance, which can effectively resist the invasion of external impact objects and prevent being pierced or torn. The inner core reinforcing structure 200 is a honeycomb structure, which plays the role of "energy absorption box". When impacted, the inner core reinforcing structure 200 will efficiently disperse and absorb huge impact energy through ordered deformation, avoiding damage caused by concentrated force. The protection performance not only meets but also exceeds the most stringent international safety standards (such as EN ISO 20345), providing top-level life safety protection for users.

[0142] (3) High toughness and fatigue resistance. The thermoplastic nylon matrix itself has excellent toughness, and after being combined with glass fibers, its impact toughness is much higher than that of brittle thermosetting resins or ordinary plastics, and it is not easy to cause sudden brittle fracture. The safety toe cap has higher durability and longer service life, and even after multiple minor impacts, the performance decay is much smaller than other materials.

[0143] (4) The structure is firm and has no weak points. The outer shell 100 and the inner core reinforcing structure 200 are "welded" into one body through a molten nylon base in the mold, the interface bonding strength is extremely high, there is no risk of aging and delamination of adhesives, and the stress concentration problem caused by screw connection is also avoided. The safety shoe head product has excellent structural integrity, fundamentally solves the common problem of separation (delamination) between composite material layers, and greatly improves reliability.

[0144] (5) The production process is efficient and the cost is controllable. The safety shoe head processing technology of the application includes "molding-injection", and the one-piece molding process completes all steps in about 1-2 minutes of a production cycle, realizing highly automated and large-scale production. The production efficiency is much faster than the manual layering and long curing time of the traditional technology lamination process. Although the raw material grade is high, the single-piece cost is effectively controlled due to high efficiency and production automation, the comprehensive cost is low, and it has strong market competitiveness.

[0145] (6) Chemical corrosion resistance and rust prevention. The safety shoe head of the application has a full composite material structure, which naturally resists water, salt spray, most chemicals and solvents. It is especially suitable for use in humid and corrosive environments such as chemical industry, marine, food processing, etc., and has a much longer service life than metal shoe heads.

[0146] (7) Thermal and electrical insulation. The composite material used in the safety shoe head of the application is a poor conductor of heat and electricity, which does not freeze the feet in winter and does not scald the feet in summer, providing a more comfortable wearing experience, and also providing additional safety protection for workers in the electrical industry.

[0147] (8) High design freedom. The one-piece molding process of the safety shoe head of the application can produce very complex internal honeycomb structures and external streamlined curves, which is difficult to achieve by traditional technology metal stamping, and can design a shoe head internal space that is more ergonomic, further improving the wearing comfort.

[0148] In the above embodiments, the description of each embodiment has its own emphasis, and the parts not described in detail in a certain embodiment can be referred to the related description of other embodiments.

[0149] Each technical feature of the above-described embodiments can be combined arbitrarily, and in order to make the description concise, not all possible combinations of the technical features in the above-described embodiments are described, however, as long as the combination of the technical features does not exist contradictory, it should be considered as the scope of the present disclosure.

[0150] The above-described embodiments are merely illustrative of several embodiments of the present application, which are described in more detail and in a specific manner, but should not be construed as limiting the scope of the patent of the present application. It should be noted that, for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A lightweight safety toe, comprising: The light-weight safety shoe head comprises an outer shell and an inner core reinforcing structure, the outer shell is connected to the outer wall of the inner core reinforcing structure, the outer shell is made of thermoplastic composite material containing 60wt%-70wt% reinforcing continuous fibers, the inner core reinforcing structure is made of thermoplastic injection material containing 30wt%-50wt% reinforcing long fibers, and the inner core reinforcing structure has a three-dimensional honeycomb structure.

2. The lightweight safety toe of claim 1, wherein The matrix of the thermoplastic composite material comprises one or more of nylon, nylon 6, nylon 66, PA12, polypropylene, polycarbonate, polyether ether ketone and polyphenylene sulfide; And / or, the matrix of the thermoplastic injection material comprises one or more of nylon, nylon 6, nylon 66, PA12, polypropylene, polycarbonate, polyether ether ketone and polyphenylene sulfide.

3. The lightweight safety toe of claim 1, wherein, At least one of the following conditions is also met: (1) the reinforcing continuous fibers comprise one or more of glass fibers, carbon fibers, basalt fibers and Kevlar fibers; (2) the reinforcing continuous fibers are in the form of unidirectional tape, fabric or randomly oriented felt; (3) the length of the reinforcing long fibers is 10mm-20mm.

4. The light-weight safety toe according to any one of claims 1 to 3, wherein The outer shell and the inner core reinforcing structure are connected in an integrated structure.

5. The light-weight safety toe according to any one of claims 1 to 3, wherein At least one of the following conditions is also met: (1) the area of the three-dimensional honeycomb structure accounts for 40%-70% of the total area of the inner core reinforcing structure; (2) the honeycomb shape in the three-dimensional honeycomb structure comprises one or more of hexagonal honeycomb, square honeycomb and circular honeycomb.

6. The light-weight safety toe according to any one of claims 1 to 3, wherein The shape of the inner core reinforcing structure is adapted to the inner wall shape of the outer shell.

7. The light-weight safety toe according to any one of claims 1 to 3, wherein At least one of the following conditions is also met: (1) the thickness of the inner core reinforcing structure is 1mm-4mm; (2) the thickness of the outer shell is 2mm-6mm.

8. The light-weight safety toe according to any one of claims 1 to 3, wherein The total weight of the light-weight safety shoe head is <50g.

9. A method for preparing a lightweight safety shoe toe, characterized in that, The method comprises the following steps: cutting the fiber sheet into a predetermined shape; laying the cut fiber sheet in a predetermined direction and melting it to a softened state to form a blank; transferring the blank into a mold; controlling the mold to close and pressurize the blank to form an outer shell with a predetermined shape; and, keeping the mold pressure, injecting molten thermoplastic injection material into the cavity between the inner wall of the outer shell and the mold through the injection port on the mold to form an inner core reinforcing structure connected to the outer shell, and the thermoplastic injection material is blocked by the core on the inner wall of the mold to form a three-dimensional honeycomb structure.

10. The method of claim 9, wherein, At least one of the following conditions is also met: (1) the fiber sheet is formed by pre-impregnating reinforcing continuous fibers in thermoplastic resin, and the content of the reinforcing continuous fibers in the fiber sheet is 60wt%-70wt%; (2) using an infrared heating device to bake the laid fiber sheet to a softened state to form a blank; (3) the temperature when melted to a softened state is 220℃-400℃; (4) using a mechanical hand to transfer the blank into a mold; (5) the pressure for controlling the mold to close and pressurize the blank is 10MPa-20MPa; (6) the thermoplastic injection material contains 30wt%-50wt% reinforcing long fibers; (7) Further comprising the step of cooling and demolding: opening the mold after cooling to 60-150 DEG C, to obtain the shoe head.

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