A double fire door

Abstract

The utility model provides a kind of double-layer fire door, it is related to building fire safety technical field.The double-layer fire door includes: door frame, first door panel and second door panel;First door panel and second door panel are respectively hinged with door frame, and can rotate relative to door frame;The thickness of door frame is greater than the sum of the thickness of first door panel and second door panel, when first door panel and second door panel are in closed state, interval gap is formed between the two;The outer surface of door frame, first door panel and second door panel is provided with melamine resin plate;The inner surface of first door panel and second door panel is coated with intumescent fire retardant coating layer.The excellent flame retardance and the characteristics of releasing non-combustible gas by heating of melamine resin plate play gas phase flame-retardant effect in the early stage of fire, and actively inhibit the development of combustion;The inner surface is coated with intumescent fire retardant coating layer, which expands rapidly to form a heat-insulating carbon layer after heating, achieving passive heat insulation protection to form a double fireproof mechanism of "outer active flame-retardant + inner passive heat insulation".

Description

Technical Field

[0001] This utility model relates to the field of building fire safety technology, and in particular to a double-layer fireproof door. Background Technology

[0002] Most existing fire doors are single-layer steel or wood structures, and their fire resistance mainly relies on the internal insulation materials such as rock wool and aluminum silicate fiber, as well as the intumescent fire-retardant coating on the surface. In the event of a fire, these fire doors slow heat transfer through the low thermal conductivity of the filling materials and the carbonized layer formed by the thermal expansion of the fire-retardant coating, thus achieving fire resistance integrity and insulation for a certain period. However, traditional single-layer fire doors generally suffer from poor sealing, direct heat conduction paths, and limited fire resistance limits. Especially when faced with sustained high temperatures or direct flame impact, the door is prone to deformation and failure due to localized overheating, and it is difficult to effectively prevent smoke penetration, posing significant safety hazards.

[0003] With the continuous improvement of building safety standards, fire-resistant structures with double or multiple doors are gradually gaining attention. Some improvement solutions attempt to enhance fire resistance by installing double door panels or adding sealing strips, but they often overlook the active response mechanism of the door material in a fire, remaining at the level of passive heat insulation technology. Utility Model Content

[0004] The main technical problem to be solved by this utility model is to provide a double-layer fireproof door that can actively suppress flames.

[0005] To solve the above-mentioned technical problems, the technical solution provided by this utility model is as follows:

[0006] A double-layer fire door includes: a door frame, a first door panel, and a second door panel;

[0007] The first door panel and the second door panel are respectively hinged to the door frame and can rotate relative to the door frame to open and close;

[0008] The thickness of the door frame is greater than the sum of the thicknesses of the first door panel and the second door panel. When the first door panel and the second door panel are in a closed state, a gap is formed between them.

[0009] The outer surfaces of the door frame, the first door panel, and the second door panel are all provided with melamine resin boards.

[0010] The inner surfaces of both the first door panel and the second door panel are coated with an intumescent fire-retardant coating layer.

[0011] Furthermore, it also includes a first limiting structure and a second limiting structure;

[0012] The first limiting structure and the second limiting structure are respectively disposed on the left and right sides of the inner side of the door frame;

[0013] The first limiting structure is located on the side of the first door panel away from its hinge side, and is used to limit the first door panel when it is closed.

[0014] The second limiting structure is located on the side of the second door panel away from its hinge side, and is used to limit the second door panel when it is closed.

[0015] Furthermore, the first door panel is hinged to the left side of the door frame, and the second door panel is hinged to the right side of the door frame, so that the first door panel and the second door panel close from both sides toward the middle, forming an interlocking closed structure.

[0016] Furthermore, the door frame has a hollow structure, and the surface of the hollow cavity of the door frame is provided with an intumescent fireproof coating layer.

[0017] Furthermore, a first fireproof sealing strip is provided on the side of the first door panel away from its hinge side, and the first fireproof sealing strip abuts against the door frame when the first door panel is closed;

[0018] A second fireproof sealing strip is provided on the side of the second door panel away from its hinge side, and the second fireproof sealing strip abuts against the door frame when the second door panel is closed.

[0019] Furthermore, the coating thickness of the intumescent fire-retardant coating layer is 1.5 to 3.0 μm, and the fire resistance limit is not less than 1.5 hours.

[0020] Furthermore, the melamine resin board is bonded to the inner surfaces of the first door panel and the second door panel using a flame-retardant adhesive.

[0021] Furthermore, the thickness of the melamine resin board is 3 to 8 μm.

[0022] Furthermore, the surface of the melamine resin board is coated with a nano-silica or acrylic moisture-proof coating.

[0023] The technical solution provided by this utility model has the following technical effects:

[0024] 1. The outer surface is covered with melamine resin board, which utilizes its excellent flame retardancy and the property of releasing non-flammable gases (such as nitrogen and ammonia) when heated to play a gas-phase flame-suppressing role in the early stage of a fire, actively inhibiting the development of combustion; the inner surface is coated with an intumescent fire-retardant coating layer, which rapidly expands to form a heat-insulating char layer after being heated, achieving passive heat insulation protection. This forms a dual fire protection mechanism of "outer active flame retardancy + inner passive heat insulation", which greatly improves the overall fire protection performance.

[0025] 2. By installing a first limiting structure and a second limiting structure on the left and right sides of the inner side of the door frame, respectively, and positioning them on the door panel away from the hinge side, the final positions of the first and second door panels after closing can be precisely controlled. This ensures that both doors accurately return to their original positions each time, preventing seal failure or uneven gaps due to incomplete closure. The limiting structures also absorb the impact force of closing the door, reducing mechanical damage to the hinges and door body, and extending service life. Simultaneously, this design helps maintain the stability of the gap, ensuring its continued thermal insulation function during a fire, and improving the reliability and consistency of the fire door's operation.

[0026] 3. The first door panel is hinged on the left and the second door panel is hinged on the right, forming an interlaced closed structure. This structure not only facilitates rapid passage during emergency evacuation, making it especially suitable for densely populated areas, but also, when closed, the two door panels move towards the center from different directions, resulting in a more even distribution of force and reducing the risk of deformation caused by unilateral force.

[0027] 4. Applying an intumescent fire-retardant coating to the surface of the hollow cavity in the door frame allows it to expand and foam as the temperature rises during a fire, filling the hollow cavity and forming a continuous thermal barrier. This prevents heat from being rapidly conducted to the interior through the metal wall of the door frame, significantly improving the fire resistance and thermal insulation performance of the door frame area. This overcomes the defect of traditional door frames easily becoming "thermal bridges" and enhances the fire resistance uniformity of the overall structure. Although heat can still be transferred from the main structure of the door frame, the expansion and foaming of the intumescent fire-retardant coating reduces this heat transfer. Attached Figure Description

[0028] The above and other features and advantages of this invention will become more apparent from a detailed description of exemplary embodiments with reference to the accompanying drawings.

[0029] Figure 1 This is a front view of a double-layer fire door provided in an embodiment of this utility model;

[0030] Figure 2 This is a schematic diagram showing the first and second door panels of a double-layer fire door rotated at a certain angle, as provided in an embodiment of this utility model.

[0031] Figure 3 for Figure 1 AA section view in the image.

[0032] Explanation of reference numerals in the attached figures:

[0033] 1. Door frame; 2. First door panel; 3. Second door panel; 4. Melamine resin board; 5. Intumescent fire-retardant coating layer; 6. First limiting structure; 7. Second limiting structure. 。 Detailed Implementation

[0034] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that the present invention will be thorough and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore their detailed description will be omitted.

[0035] The terms “a,” “one,” “the,” and “the” are used to indicate the existence of one or more elements / components / etc.; the terms “including” and “having” are used to indicate an open-ended meaning of inclusion and that other elements / components / etc. may exist in addition to the listed elements / components / etc.

[0036] Figure 1 This is a front view of a double-layer fire door provided in an embodiment of this utility model; Figure 2 This is a schematic diagram showing the first and second door panels of a double-layer fire door rotated at a certain angle, as provided in an embodiment of this utility model. Figure 3 for Figure 1 The diagram above is a cross-sectional view (AA section). This diagram is only intended to illustrate the structural relationships relevant to the utility model and is not intended as a scale representation of the actual product.

[0037] like Figures 1 to 3 As shown, this utility model relates to a double-layer fire door, belonging to the field of building fire safety technology, and is particularly suitable for places with high requirements for fire resistance integrity, heat insulation performance, and smoke prevention sealing, such as hospitals, subway stations, data centers, and power distribution rooms. This double-layer fire door adopts an innovative "outer layer gas phase flame retardant + inner layer passive heat insulation" synergistic protection mechanism, combined with a double-door non-contact closure structure and multiple sealing designs, achieving excellent comprehensive fire resistance performance.

[0038] The double-layer fire door in this embodiment mainly consists of three parts: door frame 1, first door panel 2, and second door panel 3. Door frame 1, serving as the load-bearing and installation foundation of the overall structure, is made of thick cold-rolled galvanized steel sheet, CNC bent and welded into a rectangular frame structure. Door frame 1 is firmly fixed to the pre-reserved door opening in the wall using expansion bolts, ensuring that the horizontal and vertical errors are less than 2mm / m to guarantee smooth operation of the subsequent door panels.

[0039] The first door panel 2 and the second door panel 3 are rotatably connected to the door frame 1 via heavy-duty hinge assemblies. The first door panel 2 is hinged to the left column of the door frame 1, and the second door panel 3 is hinged to the right column. Both doors can be opened and closed independently. When both doors close towards the center simultaneously, they form an interlocking closing structure, which can achieve efficient sealing and fireproof isolation when closed.

[0040] Crucially, the overall thickness of the door frame 1 is significantly greater than the sum of the thicknesses of the first door panel 2 and the second door panel 3. Therefore, when both the first door panel 2 and the second door panel 3 are fully closed, they do not directly contact each other, but rather maintain a gap. This provides space for the expansion of the intumescent fire-retardant coating layer 5.

[0041] In terms of fire-resistant design, this utility model adopts a multi-level, multi-mechanism synergistic technical approach.

[0042] First, melamine resin boards 4 are installed on the outer surfaces (i.e., the fire-facing surfaces) of the door frame 1, the first door panel 2, and the second door panel 3. These melamine resin boards 4 are thermosetting plastic sheets made primarily from melamine-formaldehyde resin, molded under high temperature and pressure. They possess a high limiting oxygen index (LOI ≥ 32%), excellent dimensional stability, low smoke and non-toxic properties, and a unique gas-phase flame-retardant mechanism. The melamine resin boards 4 are firmly bonded to the outer surface of the metal substrate using a combination of flame-retardant adhesive and mechanical anchors. The flame-retardant adhesive used is a modified epoxy resin-based adhesive with a shear strength ≥ 8 MPa and a temperature resistance rating of over 180℃, ensuring no delamination or blistering under high-temperature conditions. Simultaneously, a 2-3 mm thermal expansion gap is reserved around the melamine resin boards 4 to prevent warping or cracking at high temperatures due to differences in the linear expansion coefficients of the materials.

[0043] This invention creatively places the melamine resin board 4 on the fire-facing side. Its core advantage lies in the fact that, in the early stages of a fire, when flames or high-temperature radiation act on the outer surface of the door, the melamine resin board 4 rapidly decomposes upon heating, releasing large amounts of non-combustible gases such as nitrogen (N2), ammonia (NH3), and water vapor (H2O). These gases can dilute the oxygen concentration around the combustion zone and inhibit the free radical chain reaction, thereby exerting a gas-phase flame-retardant effect and effectively slowing the spread of flames. This design achieves active flame suppression.

[0044] Secondly, an intumescent fire-retardant coating layer 5 is applied to the inner surfaces of the first door panel 2 and the second door panel 3 (i.e., the side of the first door panel 2 closest to the second door panel 3 and the side of the second door panel 3 closest to the first door panel 2 when the first door panel 2 and the second door panel 3 are closed), as well as to the inner surface of the hollow cavity in the door frame 1. This coating is a water-based intumescent fire-retardant coating for steel structures, and its main components are ammonium polyphosphate (foaming agent), pentaerythritol (charring agent), melamine (synergist), and silicate filler. At room temperature, the coating adheres stably, providing both corrosion protection and decoration. When the ambient temperature rises above 150°C, the coating begins to react violently, rapidly expanding in volume by 6 to 8 times, forming a porous, loose but dense carbonized foam insulation layer that effectively isolates heat conduction. According to the configuration of this embodiment, the dry film thickness of the intumescent fireproof coating layer 5 is controlled at 2.0 μm. According to the test conducted by the National Fire Equipment Quality Supervision and Inspection Center in accordance with GB / T 9978-2008 "Fire Resistance Test Method for Building Components", its fire resistance limit reaches 1.6 hours, and the average temperature rise on the unexposed surface is less than 140°C, which meets the Class A fire door standard.

[0045] To further improve closing accuracy and reliability, this invention also includes a first limiting structure 6 and a second limiting structure 7. These two limiting structures are respectively located at the stops on the left and right side frames inside the door frame 1, corresponding to the free edge edges of the first door panel 2 and the second door panel 3. The first limiting structure 6 is located on the side of the first door panel 2 away from its hinge side, used to limit its closing stroke and achieve precise positioning; similarly, the second limiting structure 7 is used for the second door panel 3. The limiting structures use silicone rubber elastic blocks with a Shore A hardness of 60±5, which can absorb the impact force of closing the door, reduce noise, and achieve slight buffering rebound, ensuring accurate positioning of the door panel.

[0046] In addition, a first fireproof sealing strip and a second fireproof sealing strip are respectively provided at the edges of the first door panel 2 and the second door panel 3 away from the hinge side. These fireproof sealing strips are usually made of flexible high-temperature resistant materials, such as expandable graphite tape, silicone rubber, or composite fireproof expandable sealing strips. It is particularly preferred to use heat-expandable fireproof sealing strips, whose core material is expandable graphite or acrylate polymer. When the ambient temperature reaches 70°C to 150°C, the volume of the sealing strip can expand 2 to 5 times, quickly filling the gap between the door panel and the door frame 1, preventing the penetration of flames, high-temperature gases, and toxic fumes, and achieving dynamic sealing to prevent the penetration of flames, high-temperature gases, and toxic fumes.

[0047] This utility model can also be adapted into various other implementations: for example, the interior of the door panel can be filled with fire-resistant and heat-insulating core materials such as aluminum silicate fiberboard, rock wool board, or expanded perlite board to further improve thermal resistance performance; while the inner surface of the hollow cavity of the door frame 1 is coated with an intumescent fire-retardant coating, a melamine resin board 4 can also be added as an inner reinforcing layer; the hinge between the door panel and the door frame 1 can be a concealed hinge, a multi-point linkage locking mechanism, or an automatic door closer to improve aesthetics and safety; the surface of the melamine resin board 4 can also be coated with a nano-silica or acrylic moisture-proof coating (thickness 20μm~50μm) to cope with the problem of moisture absorption and deformation in humid environments.

[0048] In summary, the double-layer fire door provided by this utility model achieves excellent fire resistance, heat insulation, smoke prevention and structural stability through the synergistic effect of multiple fire prevention mechanisms, including the active flame retardancy of the outer melamine resin board 4 and the passive heat insulation of the inner intumescent fire-retardant coating, the thermal blocking effect of the double door gap, the dynamic sealing of the heat-expanding sealing strip, and a reasonable structural layout design. It has broad market application prospects and technical promotion value.

Claims

1. A double-layer fireproof door, characterized in that, include: Door frame (1), first door panel (2), and second door panel (3); The first door panel (2) and the second door panel (3) are respectively hinged to the door frame (1) and can rotate relative to the door frame (1) to open and close; The thickness of the door frame (1) is greater than the sum of the thicknesses of the first door panel (2) and the second door panel (3). When the first door panel (2) and the second door panel (3) are in a closed state, a gap is formed between them. The outer surfaces of the door frame (1), the first door panel (2) and the second door panel (3) are all provided with melamine resin boards (4); The inner surfaces of the first door panel (2) and the second door panel (3) are coated with an intumescent fire-retardant coating layer (5).

2. A double-layer fireproof door according to claim 1, characterized in that, It also includes a first limiting structure (6) and a second limiting structure (7); The first limiting structure (6) and the second limiting structure (7) are respectively disposed on the left and right sides inside the door frame (1); The first limiting structure (6) is located on the side of the first door panel (2) away from its hinge side, and is used to limit the first door panel (2) when it is closed. The second limiting structure (7) is located on the side of the second door panel (3) away from its hinge side, and is used to limit the second door panel (3) when it is closed.

3. A double-layer fireproof door according to claim 1, characterized in that, The first door panel (2) is hinged to the left side of the door frame (1), and the second door panel (3) is hinged to the right side of the door frame (1), so that the first door panel (2) and the second door panel (3) close from both sides to the middle, forming an interlocking closed structure.

4. A double-layer fireproof door according to claim 1, characterized in that, The door frame (1) is a hollow structure, and the surface of the hollow cavity of the door frame (1) is provided with an intumescent fireproof coating layer (5).

5. A double-layer fireproof door according to claim 1, characterized in that, A first fireproof sealing strip is provided on the side of the first door panel (2) away from its hinge side, and the first fireproof sealing strip abuts against the door frame (1) when the first door panel (2) is closed; A second fireproof sealing strip is provided on the side of the second door panel (3) away from its hinge side, and the second fireproof sealing strip abuts against the door frame (1) when the second door panel (3) is closed.

6. A double-layer fireproof door according to claim 1, characterized in that, The coating thickness of the intumescent fireproof coating layer (5) is 1.5 to 3.0 m, and the fire resistance limit is not less than 1.5 hours.

7. A double-layer fireproof door according to claim 1, characterized in that, The melamine resin board (4) is bonded to the inner surfaces of the first door panel (2) and the second door panel (3) by flame-retardant adhesive. 。 8. A double-layer fireproof door according to claim 1, characterized in that, The thickness of the melamine resin board (4) is 3-8 μm.

9. A double-layer fireproof door according to claim 1, characterized in that, The surface of the melamine resin board (4) is coated with nano-silica or acrylic moisture-proof coating.

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