A flexible conductive film for electrically heating tire curing bladder and its processing method

Abstract

A flexible conductive film and processing method for electrically heating a tire vulcanization bladder belong to the field of tire vulcanization bladders and the field of tire manufacturing. The present invention includes a flexible base layer, a conductive layer, an encapsulation layer and a flexible electrode, the conductive layer is arranged between the flexible base layer and the encapsulation layer, the flexible electrode is connected to the conductive layer, and the conductive layer is made of a mixture of at least one one-dimensional conductive nanomaterial and at least one two-dimensional conductive nanomaterial. The research and development purpose of the present invention is to solve the problem that traditional conductive heating films are prone to breakage due to stress concentration during use, especially during expansion and contraction. The flexible stretchable conductive heating film significantly improves its stretchability by optimizing the material formula and structural design, and is not prone to breakage, thereby extending its service life and reducing the frequency of replacement and maintenance. It can better adapt to the deformation of the vulcanization bladder, ensuring that the heating film is always in close contact with the inner surface of the bladder, and achieving a more uniform heating effect.

Description

Technical Field

[0001] The invention relates to a flexible conductive film for electrically heating a tire vulcanizing bladder and a processing method thereof, belonging to the field of tire vulcanizing bladders. Background Art

[0002] Tire vulcanization is a crucial step in the tire manufacturing process, and the curing bladder plays a key role. Traditional curing bladders typically use heating tubes or cables for heating, which can lead to high energy consumption, uneven heating, and poor control accuracy. Conductive heating films, as a new heating technology, have been gaining attention in the tire vulcanization industry in recent years. Conductive heating films are devices that utilize Joule heating generated by an electric current passing through a conductive material coated on a film substrate to generate heat. Compared to traditional heating methods, conductive heating films offer advantages such as uniform heating, low energy consumption, fast response, and high control accuracy. The application of conductive heating films in tire curing bladders can significantly improve vulcanization efficiency and tire quality. Furthermore, the flexible nature of conductive heating films allows them to better conform to the inner surface of the bladder, achieving more uniform heating. Furthermore, the use of conductive heating films can reduce equipment maintenance costs and energy consumption, improving production efficiency and environmental friendliness. In summary, the application of conductive heating films in tire curing bladders not only improves production efficiency and product quality, but also brings significant economic and environmental benefits, demonstrating their broad application prospects. However, traditional conductive heating films are prone to breakage due to stress concentration during use, especially during expansion and contraction.

[0003] Therefore, it is urgent to propose a new type of flexible conductive film and processing method for electrically heating tire curing bladders to solve the above technical problems. Summary of the Invention

[0004] The present invention is developed to address the problem of conventional conductive heating films being susceptible to fracture during use, particularly during expansion and contraction, due to stress concentration. The following is a brief overview of the present invention to provide a basic understanding of certain aspects of the present invention. It should be understood that this overview is not an exhaustive overview of the present invention. It is not intended to identify key or important aspects of the present invention, nor is it intended to limit the scope of the present invention.

[0005] The technical solution of the present invention:

[0006] Solution 1: A flexible conductive film for electrically heating a tire curing bladder, comprising a flexible base layer, a conductive layer, an encapsulation layer, and a flexible electrode. The conductive layer is disposed between the flexible base layer and the encapsulation layer, and the flexible electrode is connected to the conductive layer. The conductive layer is made of a mixture of at least one one-dimensional conductive nanomaterial and at least one two-dimensional conductive nanomaterial.

[0007] Preferably, the one-dimensional conductive nanomaterial and the two-dimensional conductive nanomaterial are mixed in a weight ratio of 1:0.5-3.

[0008] Preferably, the flexible base layer and the packaging layer are made of raw rubber, and the flexible electrodes are made of carbon fiber wires or metal wires.

[0009] Preferably, the conductive layer is one or more combinations of carbon nanotubes, graphene, and MXene conductive materials.

[0010] Preferably, the one-dimensional conductive nanomaterial includes carbon nanotubes and / or metal nanowires, and the two-dimensional conductive nanomaterial includes graphene, MXene and / or MoS2.

[0011] Solution 2: A method for processing a flexible conductive film for electrically heating a tire curing bladder is based on the flexible conductive film for electrically heating a tire curing bladder described in Solution 1, and includes the following steps:

[0012] S1: preparing a flexible substrate: pre-compressing the raw rubber into a sheet shape to form a flexible substrate;

[0013] S2: Designing a conductive layer: preparing one or more of carbon nanotubes, graphene, and MXene conductive materials into a conductive layer;

[0014] S3: Preparing a conductive layer on a flexible substrate: dispersing at least one one-dimensional conductive nanomaterial, at least one two-dimensional conductive nanomaterial, and raw rubber powder selected in a weight ratio into alcohol and performing ultrasonic treatment to obtain a mixed conductive layer material;

[0015] The mixed conductive layer material is dried at 50°C and pressed into sheets;

[0016] S4: preparing the encapsulation layer: pre-compressing the raw rubber into a sheet shape to prepare the encapsulation layer;

[0017] S5: preparing a flexible conductive film: stacking the flexible substrate, the conductive layer, and the packaging layer in this order, and then performing a vulcanization treatment to form a vulcanized integral body.

[0018] Preferably, the conductive layer is prepared in 10 layers in total, wherein the proportion of raw rubber powder in the conductive layers from 1 to 5 gradually decreases, and the proportion of raw rubber powder in the conductive layers from 5 to 9 gradually increases.

[0019] Preferably, the flexible electrode is also laid between the flexible substrate and the packaging layer, and is integrally formed together with the conductive layer through vulcanization.

[0020] Preferably, the raw rubber in step S1 is the same as the raw rubber in step S5, and the raw rubber is natural rubber, styrene-butadiene rubber, polybutadiene rubber, isoprene rubber, silicone rubber, chloroprene rubber, butyl rubber, nitrile rubber, ethylene-propylene rubber or fluororubber.

[0021] Preferably, the heating power P of the flexible conductive film is:

[0022]

[0023] Wherein, σ is the conductivity of the flexible conductive film, b is the width of the flexible conductive film, d is the thickness of the flexible conductive film, U is the voltage applied to the flexible conductive film, and L is the length of the flexible conductive film.

[0024] The present invention has the following beneficial effects:

[0025] 1. The flexible conductive film of the present invention is used for electrically heating a tire curing bladder. By optimizing the material formulation and structural design, the flexible, stretchable conductive heating film significantly improves its stretchability and is less prone to breakage, thereby extending its service life and reducing the frequency of replacement and maintenance.

[0026] 2. The flexible conductive film of the present invention is used for electrically heating a tire curing bladder. During the tire curing process, the flexible and stretchable conductive heating film can better adapt to the deformation of the curing bladder, preventing the flexible conductive film from breaking when the bladder expands and contracts. It also ensures that the heating film always adheres to the inner surface of the bladder, achieving a more uniform heating effect.

[0027] 3. The present invention provides a method for processing a flexible conductive film for an electrically heated tire curing bladder, standardizing the processing technology of the flexible conductive film. The preparation process is simple and easy, does not require complicated equipment and process steps, has high production efficiency and a fast production cycle, can achieve large-scale, high-speed production, and obtain high-quality flexible conductive film in a relatively short time. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A front view of a flexible conductive membrane used for electrically heating a tire curing bladder;

[0029] Figure 2 yes Figure 1 Side view of

[0030] Figure 3 A diagram of a flexible conductive film for electrically heating a tire curing bladder being attached to the outside of the curing bladder;

[0031] Figure 4 A diagram of a flexible conductive film for electrically heating a tire curing bladder, attached to the inner side of the curing bladder;

[0032] Figure 5 A diagram of a flexible conductive film for electrically heating a tire curing bladder, attached to the inner wall of the curing bladder;

[0033] Figure 6 A schematic diagram of heating a flexible conductive film for electrically heating a tire curing bladder;

[0034] Figure 7 The figure shows the temperature rise curve of a flexible conductive film used for electrically heating a tire curing bladder under different applied voltages.

[0035] In the figure, 1-flexible base layer, 2-conductive layer, 3-encapsulation layer, 4-flexible electrode. DETAILED DESCRIPTION

[0036] To make the objectives, technical solutions, and advantages of the present invention more clearly apparent, the present invention is described below using specific embodiments shown in the accompanying drawings. However, it should be understood that these descriptions are merely illustrative and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present invention.

[0037] The connections mentioned in the present invention are divided into fixed connections and detachable connections. The fixed connection refers to a non-detachable connection, including but not limited to conventional fixed connection methods such as hem connection, rivet connection, adhesive connection, and welding connection. The detachable connection refers to but not limited to conventional detachable connection methods such as threaded connection, snap connection, pin connection, and hinge connection. When the specific connection method is not clearly specified, it is assumed that at least one connection method can always be found among the existing connection methods to achieve the function. Those skilled in the art can choose according to their needs. For example, a welded connection is selected for a fixed connection, and a hinge connection is selected for a detachable connection.

[0038] Specific implementation method 1: Combination Figure 1-Figure 7 This embodiment describes a flexible conductive film for electrically heating a tire curing bladder, comprising a flexible base layer 1, a conductive layer 2, an encapsulation layer 3, and a flexible electrode 4. The conductive layer 2 is disposed between the flexible base layer 1 and the encapsulation layer 3, and the flexible electrode 4 is connected to the conductive layer 2. The conductive layer 2 is made of a mixture of at least one one-dimensional conductive nanomaterial and at least one two-dimensional conductive nanomaterial.

[0039] The one-dimensional conductive nanomaterial and the two-dimensional conductive nanomaterial are mixed in a weight ratio of 1:0.5-3.

[0040] The flexible base layer 1 and the packaging layer 3 are made of raw rubber, and the flexible electrode 4 is made of carbon fiber wire or metal wire.

[0041] The conductive layer 2 is one or more combinations of carbon nanotubes, graphene, and MXene conductive materials.

[0042] The one-dimensional conductive nanomaterial includes carbon nanotubes and / or metal nanowires, and the two-dimensional conductive nanomaterial includes graphene, MXene and / or MoS2.

[0043] The flexible conductive film of this embodiment can be attached to any position on the inside, outside, or inside the wall of the vulcanization bladder. Those skilled in the art can arrange it according to actual needs, and the flexible conductive film must be arranged when the vulcanization bladder is in the maximum deformation working state.

[0044] Specific implementation method 2: Combination Figure 1-Figure 7 This embodiment describes a method for processing a flexible conductive film for electrically heating a tire curing bladder. This method is based on the flexible conductive film for electrically heating a tire curing bladder described in the first embodiment and includes the following steps:

[0045] S1: preparing a flexible substrate 1: pre-compressing the raw rubber into a sheet shape to form a flexible substrate 1;

[0046] S2: Designing a conductive layer 2: preparing one or more conductive materials selected from carbon nanotubes, graphene, and MXene into a conductive layer 2;

[0047] S3: 1. Preparing a conductive layer on a flexible substrate 2. Dispersing at least one one-dimensional conductive nanomaterial, at least one two-dimensional conductive nanomaterial, and raw rubber powder selected in proportion by weight into alcohol and ultrasonically treating the mixture to obtain a mixed conductive layer material;

[0048] The mixed conductive layer material is dried at 50°C and pressed into sheets;

[0049] S4: preparing the encapsulation layer 3: pre-compressing the raw rubber into a sheet shape to prepare the encapsulation layer 3;

[0050] S5: Preparing a flexible conductive film: The flexible substrate 1, conductive layer 2, and encapsulation layer 3 are stacked in this order, and then vulcanized to form a vulcanized integral unit. The flexible electrode 4 is also laid between the flexible substrate 1 and the encapsulation layer 3 and vulcanized integrally with the conductive layer 2.

[0051] Because the flexible conductive film's internal gradient design—flexible substrate 1, conductive layer 2, and encapsulation layer 3—ensures good interlayer bonding. A flexible electrode 4 is laid atop the conductive layer 2, and then the encapsulation layer 3 is placed atop the flexible electrode 4. After vulcanization and integrated molding, the flexible conductive film for electrically heated tire curing bladders is produced.

[0052] The conductive layer 2 is prepared into 10 layers in total, wherein the proportion of raw rubber powder in the conductive layers 2 of layers 1 to 5 gradually decreases, and the proportion of raw rubber powder in the conductive layers 2 of layers 5 to 9 gradually increases.

[0053] The raw rubber in step S1 is the same as the raw rubber in step S5, and the raw rubber is natural rubber, styrene-butadiene rubber, polybutadiene rubber, isoprene rubber, silicone rubber, chloroprene rubber, butyl rubber, acrylonitrile-butadiene rubber, ethylene-propylene rubber or fluororubber.

[0054] The heating power P of the flexible conductive film is:

[0055]

[0056] Wherein, σ is the conductivity of the flexible conductive film, σ is 10-50 S / m, b is the width of the flexible conductive film, d is the thickness of the flexible conductive film, and d<5 mm, U is the voltage applied to the flexible conductive film, and the voltage U is 220-380 V AC or DC. The external power selection input is regulated according to the vulcanization temperature of 120-260° C., and L is the length of the flexible conductive film.

[0057] The flexible conductive film of this embodiment can be in any shape, such as square, rectangle, hexagon, irregular shape, etc. Those skilled in the art can prepare it according to actual needs.

[0058] Specific implementation method three: Combination Figure 1-Figure 7 This embodiment describes a method for processing a flexible conductive film for electrically heating a tire curing bladder. This method is based on the flexible conductive film for electrically heating a tire curing bladder described in the second embodiment and includes the following steps:

[0059] S1: preparing a flexible substrate 1: pre-compressing the raw rubber into a sheet shape to form a flexible substrate 1;

[0060] S2: Design conductive layer 2: Mix carbon nanotube material and two-dimensional graphene material in a weight ratio of 1:1 to form a conductive heating powder to prepare conductive layer 2; the carbon nanotubes used have a diameter of 8–15 nm and a length of 8-14 μm, and the graphene has a thickness of 1-3 layers, each layer is 1-5 nm, and a diameter of 7-12 μm.

[0061] S3: Preparing a conductive layer 2 on a flexible substrate 1: dispersing carbon nanotubes, graphene and raw rubber powder selected according to a weight ratio into alcohol, and performing ultrasonic treatment to obtain a mixed conductive layer material. A total of 10 layers of the conductive layer 2 are prepared, and the proportion of raw rubber powder in layers 1 to 5 gradually decreases, and the proportion of raw rubber powder in layers 5-9 gradually increases. The weight ratios of the conductive heating powder and the raw rubber powder in layers 1-9 of the conductive layer 2 are 4:1, 3:1, 2:1, 1:1, 0:1, 1:1, 2:1, 3:1, and 4:1, respectively;

[0062] The mixed conductive layer material is dried at 50°C and pressed into sheets;

[0063] S4: preparing the encapsulation layer 3: pre-compressing the raw rubber into a sheet shape to prepare the encapsulation layer 3;

[0064] S5: Preparing a flexible conductive film: The flexible substrate 1, conductive layer 2, and encapsulation layer 3 are stacked in this order, with the conductive layer 2 stacked in layers 1-9, and then vulcanized to form a vulcanized integral unit. The flexible electrode 4 is also laid between the flexible substrate 1 and the encapsulation layer 3 and vulcanized together with the conductive layer 2 to form a single unit.

[0065] The size L×b×d of the entire flexible heating film is 10cm*2cm*0.5cm. The heating rate of the flexible heating film produced on the side at 50V, 150V and 220V is ensured to meet the design requirements.

[0066] The flexible conductive heating film prepared in this embodiment was tested by a uniaxial tensile testing machine at a test speed of 50 mm / min and a set maximum strain rate of 200%. The flexible conductive heating film prepared in this embodiment was tested by a conductivity tester, and the conductivity σ was 30 S / m. Voltages of 50 V, 150 V, and 220 V were applied to both ends of the flexible heating film prepared in this embodiment. Figure 5 The temperature range of the infrared temperature tester is 0~275℃, see Figure 7 .

[0067] It should be noted that in the above embodiments, as long as the technical solutions are not contradictory, they can be permuted and combined. Those skilled in the art can exhaust all possibilities based on the mathematical knowledge of permutations and combinations. Therefore, the present invention will no longer describe the technical solutions after permutations and combinations one by one, but it should be understood that the technical solutions after permutations and combinations have been disclosed by the present invention.

[0068] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A flexible conductive film for electrically heating a tire curing bladder, characterized by: The invention comprises a flexible base layer (1), a conductive layer (2), an encapsulation layer (3) and a flexible electrode (4), wherein the conductive layer (2) is arranged between the flexible base layer (1) and the encapsulation layer (3), and the flexible electrode (4) is connected to the conductive layer (2), and the conductive layer (2) is made of a mixture of at least one one-dimensional conductive nanomaterial and at least one two-dimensional conductive nanomaterial; The flexible base layer (1) and the packaging layer (3) are made of raw rubber, and the flexible electrode (4) is made of carbon fiber wire or metal wire; The conductive layer (2) is one or more combinations of carbon nanotubes, graphene, and MXene conductive materials; The conductive layer (2) is prepared in total of 10 layers, wherein the proportion of raw rubber powder in the conductive layers (2) of layers 1 to 5 gradually decreases, and the proportion of raw rubber powder in the conductive layers (2) of layers 5 to 9 gradually increases; The heating power of the flexible conductive film for: ； Wherein, σ is the conductivity of the flexible conductive film, σ is 10-50 S / m, b is the width of the flexible conductive film, d is the thickness of the flexible conductive film, and d is less than 5 mm, U is the voltage applied to the flexible conductive film, and the voltage U is 220-380 V AC or DC, and the external power input is regulated according to the curing temperature of 120-260°C, and L is the length of the flexible conductive film; The flexible conductive film is randomly attached to the inner side, outer side, or inner wall of the vulcanizing bladder; Also included is a method for processing a flexible conductive film for electrically heating a tire curing bladder, which is realized by relying on the flexible conductive film for electrically heating a tire curing bladder, and includes the following steps: S1: preparing a flexible base layer (1): pre-compressing the raw rubber into a sheet shape to prepare a flexible base layer (1); S2: Designing a conductive layer (2): preparing one or more of carbon nanotubes, graphene, and MXene conductive materials into a conductive layer (2); S3: preparing a conductive layer (2) on the flexible base layer (1): dispersing at least one one-dimensional conductive nanomaterial, at least one two-dimensional conductive nanomaterial and raw rubber powder selected in proportion by weight into alcohol and performing ultrasonic treatment to obtain a mixed conductive layer material; The mixed conductive layer material is dried at 50°C and pressed into sheets; S4: preparing the encapsulation layer (3): pre-compressing the raw rubber into a thin sheet to form the encapsulation layer (3); S5: preparing a flexible conductive film: stacking the flexible base layer (1), the conductive layer (2), and the encapsulation layer (3) in this order, and then performing a vulcanization treatment to form a vulcanized integral body.

2. The flexible conductive film for electrically heating a tire curing bladder according to claim 1, characterized in that: The one-dimensional conductive nanomaterial and the two-dimensional conductive nanomaterial are mixed in a weight ratio of 1:0.5-3.

3. The flexible conductive film for electrically heating a tire curing bladder according to claim 2, characterized in that: The one-dimensional conductive nanomaterial includes carbon nanotubes and / or metal nanowires, and the two-dimensional conductive nanomaterial includes graphene, MXene and / or MoS2.

4. The flexible conductive film for electrically heating a tire curing bladder according to claim 3, characterized in that: The flexible electrode (4) is also laid between the flexible base layer (1) and the packaging layer (3), and is integrally formed together with the conductive layer (2) through vulcanization.

5. The flexible conductive film for electrically heating a tire curing bladder according to claim 4, characterized in that: The raw rubber in step S1 is the same as the raw rubber in step S5, and the raw rubber is natural rubber, styrene-butadiene rubber, polybutadiene rubber, isoprene rubber, silicone rubber, chloroprene rubber, butyl rubber, acrylonitrile-butadiene rubber, ethylene-propylene rubber or fluororubber.

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