Electric heating film, packaged floor heating structure and low-voltage electric floor heating system suitable for humid environments

Abstract

The present invention discloses an electric heating film suitable for a humid environment, a packaged floor heating structure having the electric heating film, and a low-voltage electric floor heating system. The electric heating film includes a substrate layer, a carbon film, and an electrode arranged between the substrate layer and the carbon film. An adhesive material for bonding the substrate layer, the carbon film, and the electrode is also arranged between the substrate layer and the carbon film. The carbon film is prepared by an aqueous conductive slurry, and the aqueous conductive slurry includes a resin component, a conductive component, and a hydrophobic additive. The resin component includes a first polyurethane resin with a glass transition temperature of ≤15°C and a second polyurethane resin with a glass transition temperature of ≥25°C. The low-voltage electric floor heating system includes the packaged floor heating structure and a low-voltage power supply device for providing a voltage of 2~58V. The electric heating film provided by the present invention has excellent high temperature and high humidity resistance, and has stable performance in a humid environment. The electric floor heating system based on the electric heating film has both system safety and material durability, and can be truly suitable for use in a humid environment.

Description

Technical Field

[0001] The present invention belongs to the technical field of electric floor heating, and in particular relates to an electric heating film suitable for humid environments, a packaged floor heating structure and a low-voltage electric floor heating system. Background Art

[0002] The electric floor heating system is a new type of floor radiation heating method that is different from the traditional water floor heating system. The electric floor heating system uses conductive heating materials as the heating element. The conductive heating materials with an upper limit of about 65°C on the surface are laid under the floor, tiles, marble and other finishing materials, and the heating temperature of the heating materials is controlled by a thermostat to achieve floor radiation heating. Compared with traditional heating methods, the electric floor heating system has the advantages of comfort, environmental protection, high efficiency and energy saving, no maintenance, independent use of each room, and concealed installation.

[0003] With the improvement of the quality of life, people's demand for comfortable and convenient heating methods is also increasing. Not only low-humidity areas such as living rooms, bedrooms, and study rooms need to be equipped with electric floor heating, but also areas with relatively high humidity such as bathrooms need to have floor heating systems. Compared with water-heating pipe floor heating, electric floor heating is more flexible in laying, which solves the problem that water-heating pipes cannot be laid in the bathroom, and can be used directly in the bathroom. However, the existing electric floor heating system cannot really meet the use needs in high-humidity environments. On the one hand, as the core heating structure in the electric floor heating system, the electric heating film is basically directly powered by the 220V municipal voltage. For high-humidity environments, the 220V voltage has a high safety risk. Once the anti-leakage protection measures of the electric floor heating system are not in place, coupled with the high environmental and ground humidity, leakage safety problems are likely to occur. On the other hand, the existing electric heating film has unstable performance in a humid environment for a long time, and its power is easily attenuated when it encounters water or moisture, and its service life is short.

[0004] At present, some researchers use transformers to convert municipal voltage into a human safety voltage below 36V. For example, the patent application with publication number CN104033953A improves the safety performance of the electric floor heating system, but does not make targeted improvements to the structure and performance of the electric heating film itself. The electric heating film still cannot achieve ideal operating results in a humid environment. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide an electric heating film which is truly suitable for a humid environment in view of the shortcomings and deficiencies of the prior art.

[0006] The present invention further provides a packaged floor heating structure and a low-voltage electric floor heating system suitable for humid environments, which have both system safety and material safety and can be used safely, stably and efficiently in humid environments.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] Disclosed is an electric heating film suitable for a humid environment, the electric heating film comprising a substrate layer, a carbon film, and an electrode arranged between the substrate layer and the carbon film; an adhesive material for bonding the substrate layer, the carbon film and the electrode is also arranged between the substrate layer and the carbon film; the carbon film is prepared by using an aqueous conductive slurry, the aqueous conductive slurry comprises a resin component, a conductive component and a hydrophobic additive, the resin component comprises a first polyurethane resin with a glass transition temperature of ≤15°C and a second polyurethane resin with a glass transition temperature of ≥25°C.

[0009] Preferably, the substrate layer includes a first substrate layer and a second substrate layer, the carbon film is located between the first substrate layer and the second substrate layer, the electrode includes a first electrode portion combined with the carbon film and partially located between the carbon film and the first substrate layer, and a second electrode portion covered on a portion of the first electrode portion and located between the first electrode portion and the second substrate layer, the first substrate layer and the second substrate layer, the carbon film and the second substrate layer, and the second substrate layer and the electrode are all bonded by adhesive materials, the first electrode portion and the second electrode portion use different electrode materials, the first substrate layer includes a substrate and a resin coating located on one side of the substrate, the carbon film is formed by coating the water-based conductive paste on the resin coating and curing it, and the first electrode portion is formed by coating the first electrode material on the resin coating and curing it. With this structural setting, the adhesion between the layers of the electric heating film is improved, and peeling between different layers when working in a humid environment is prevented, so that the electric heating film can maintain stable working performance in a high temperature and high humidity environment.

[0010] In some specific embodiments, the first electrode material is a silver material, specifically a micrometer-scale or nanometer-scale silver material, wherein nanometer-scale silver is more easily oxidized, and thus micrometer-scale silver is preferred; the electrode material of the second electrode portion is nickel-plated copper foil.

[0011] Furthermore, the width of the entire electrode is generally 10 to 25 mm, the width of the first electrode portion is 5 to 20 mm, and the width of the second electrode portion is 5 to 20 mm.

[0012] Furthermore, the electrodes are respectively arranged on opposite sides of the substrate layer. Each of the electrodes extends along the length direction of the substrate layer, wherein the half-width portion of the first electrode portion along the length direction is electrically connected to the carbon film, the second electrode portion is consistent with the extension direction of the first electrode portion, and the second electrode portion is located between the other half-width portion of the first electrode portion and the second substrate layer, and the second electrode portion is closely attached to the other half-width portion of the first electrode portion to form an electrical connection.

[0013] In some preferred embodiments, the first substrate layer and the second substrate layer both use PET film as the base film.

[0014] In some preferred embodiments, the adhesive material is a combination of one or more selected from polyurethane glue, epoxy resin glue, acrylic glue, and silicone glue, preferably polyurethane glue.

[0015] In some preferred embodiments, the resin coating is one or both selected from polyurethane resin and epoxy resin, preferably polyurethane resin.

[0016] In some preferred embodiments, the hydrophobic additive is a combination of one or more selected from organic silicon compounds, fluorine-containing low molecular weight resins, paraffin emulsions, and aqueous dispersions of polytetrafluoroethylene modified waxes. The hydrophobic additive can improve the hydrophobicity of the aqueous conductive slurry and effectively prevent water in the environment from entering the carbon film.

[0017] In some preferred embodiments, the hydrophobic additive accounts for 0.1% to 1% of the aqueous conductive paste in terms of mass percentage.

[0018] Preferably, the mass ratio of the first polyurethane resin to the second polyurethane resin is less than 1, and more preferably 1:1-4.

[0019] Preferably, the number average molecular weights of the first polyurethane resin and the second polyurethane resin are respectively ≥ 250,000.

[0020] As a preferred embodiment of the present invention, the second polyurethane resin is a polyurethane resin prepared by using one or more combinations selected from isocyanate raw materials selected from isotoluene diisocyanate (TDI), xylene methane diisocyanate (MDI), xylene diisocyanate (XDI), and dicyclohexylmethane diisocyanate (HMDI). The inventors found in a large number of experimental studies that when this type of second polyurethane resin is used in combination with the first polyurethane resin, the square resistance of the prepared carbon film can be unexpectedly reduced by 20% to 50% under the same conductive component and dosage, while maintaining certain mechanical properties such as tensile strength and elongation at break, so that the composite use will not cause the carbon film to be too brittle. This may be due to the effect of rigid structures such as benzene rings and π conjugated structures contained in this type of polyurethane resin. On the one hand, these polyurethane resins can provide a certain mechanical strength for the carbon film in the entire system; on the other hand, these polyurethane resins show a higher shrinkage rate when cured, which reduces the distance between conductive particles and reduces the square resistance of the carbon film.

[0021] Preferably, the mass ratio of the resin component to the conductive component is 1:1-4.

[0022] Preferably, the conductive component is one or a combination of carbon nanotubes, graphene, graphite powder, and conductive carbon black. Nanocarbon materials have low resistivity and excellent conductivity, can be applied to low voltage systems, and have uniform heating and high heating efficiency.

[0023] In some preferred embodiments, the carbon nanotubes are a combination of one or more of single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, carboxylated carbon nanotubes, and hydroxylated carbon nanotubes.

[0024] In some preferred embodiments, the carbon nanotubes have a diameter of 2 to 150 nm and a length of 1 to 50 μm.

[0025] In some preferred embodiments, the graphene sheet has a diameter of 1 to 10 μm and a thickness of 1 to 10 nm.

[0026] In some preferred embodiments, the flake diameter of the graphite powder is 1 to 10 μm.

[0027] In some preferred embodiments, the diameter of the conductive carbon black is 20 to 60 nm.

[0028] In some preferred embodiments, the conductive component is composed of 60-97% carbon nanotubes, 1-10% graphite powder, 1-10% graphene, and 1-20% conductive carbon black, by mass percentage. The conductive component is mainly composed of micro-nano carbon nanotubes, which can enhance the mechanical properties of the carbon film, and a certain amount of point-shaped conductive carbon black and flake graphite or graphene are compounded to further enhance its conductive properties.

[0029] Preferably, when preparing the aqueous conductive paste, the conductive component is mixed with the resin component in the form of a dispersion, and the dispersion of the conductive component refers to a mixed liquid that contains the conductive component, a dispersant and water and has a uniform flow dynamic as a whole.

[0030] In some preferred embodiments, in the conductive component, the mass content of the carbon nanotubes is 60-100%, and the dispersion of the conductive component further comprises a dispersing aid, which is a hyperbranched polyester having hydroxyl groups and carboxyl groups.

[0031] More preferably, the dispersing aid has a structure shown in Formula I, or is a metal salt formed by a compound having a structure shown in Formula I.

[0032]

[0033] In Formula I, n is an integer of 10 to 40, m is an integer of 5 to 20, and nm is greater than or equal to 5;

[0034] R1 represents the main structure of the hyperbranched polyester;

[0035] R2 is selected from C6-C20 chain alkyl; C2-C20 chain alkenyl; 3-8 membered ring having 1 or 2 unsaturated double bonds; phenyl which is unsubstituted or substituted with a substituent selected from C1-C6 alkyl and carboxyl; naphthyl which is unsubstituted or substituted with a substituent selected from C1-C6 alkyl and carboxyl.

[0036] In some preferred embodiments, the dispersant is a copolymer containing pigment-affinity groups.

[0037] In some preferred embodiments, in the dispersion of the conductive component, the mass content of the conductive component is 1 to 20%.

[0038] In some preferred and specific embodiments, in the dispersion of the conductive component, the mass ratio of the conductive component to the dispersant is 1:0.8 to 1.5. Preferably, the mass ratio of the conductive component to the dispersant is 1:1 to 1.2.

[0039] In some preferred embodiments, the dispersion of the conductive component further comprises a defoamer, and the mass content of the defoamer in the dispersion of the conductive component is 0.1-1%.

[0040] Preferably, the defoaming agent comprises a silicone defoaming agent and / or a polymer defoaming agent.

[0041] Further preferably, the organosilicon defoamer is selected from polydimethylsiloxane and ethylene glycol siloxane.

[0042] Further preferably, the polymer defoamer is selected from one or more of higher alcohols, polyoxyethylene oxypropylene glycerol, and copolymers of ethylene oxide and propylene oxide.

[0043] According to the present invention, the aqueous conductive paste further comprises other additives accounting for 1 to 5% by mass, and the other additives may be selected from one or more of thickeners, anti-settling agents, and film-forming aids. Among them, the thickener may be one or more of urea-modified polyurethane, polyurea, and aqueous bentonite. The anti-settling agent may be one or more of a modified urea solution, a modified polyamide solution, and a urea-modified polyurethane solution. The film-forming aid may be one or more of propylene glycol methyl ether, diethylene glycol butyl ether, dipropylene glycol methyl ether, and N-ethyl pyrrolidone.

[0044] In a specific embodiment of the present invention, the aqueous conductive paste is mixed by a dispersion containing the first polyurethane resin, a dispersion containing the second polyurethane resin, a dispersion of the conductive component, a hydrophobic additive, and a thickener, wherein the dispersion containing the first polyurethane resin is Crysol 6140, the dispersion containing the second polyurethane resin is Crysol 6136, the thickener is BYK425, and the hydrophobic additive is an aqueous dispersion of paraffin emulsion or polytetrafluoroethylene modified wax.

[0045] In some preferred embodiments, the thickness of the electric heating film is 0.2-5 mm, preferably 0.25 mm.

[0046] According to some embodiments of the present invention, the electric heating film is prepared by a method comprising the following steps:

[0047] (1) dispersing the conductive component in water in the presence of a dispersant, a dispersing aid and a selective defoaming agent to obtain a mixed solution that is uniform and dynamic as a whole, i.e., a dispersion of the conductive component;

[0048] (2) mixing the dispersion of the conductive component with other components of the aqueous conductive paste to obtain the aqueous conductive paste for standby use;

[0049] (3) A substrate with one side pre-coated with a resin coating is taken as the first substrate layer, and silver paste is applied on the left and right sides of the resin coating to form two silver paste strips, and then the aqueous conductive paste is applied on the side of the resin coating coated with the silver paste, and the conductive paste partially covers the silver paste strips, and is heated and cured to form a carbon film and a silver electrode (first electrode portion), wherein the outer portion of the silver electrode is exposed outside the carbon film; nickel-plated copper foil electrode material (second electrode portion) is continuously applied on the portion of the silver electrode exposed to the carbon film to complete the electrode production, and after an adhesive material is applied on one side of the second substrate layer, it is applied on the first substrate layer on which the electrode and the carbon film are produced, and the second substrate layer is bonded to the first substrate layer, the carbon film and the electrode through the adhesive material to obtain the electric heating film.

[0050] In some preferred embodiments, in the step (3), the silver paste is applied by a gravure printing process, and the water-based conductive paste is applied by a micro-dimpled technology.

[0051] In some preferred embodiments, in the step (1), a defoaming agent is added dropwise during the stirring and dispersing process after the conductive component is added, and grinding is performed after the defoaming agent is added dropwise.

[0052] The conductive component is first configured into a dispersion liquid for feeding, the method is simple, the operation is convenient, and the production efficiency of the dispersion liquid is greatly improved.

[0053] The present invention further provides a packaged floor heating structure, comprising the electric heating film provided by the present invention. The packaged floor heating structure also includes an insulating layer and a reflective layer sequentially arranged below the electric heating film, and a protective layer and an equipotential network sequentially arranged above the electric heating film, wherein the equipotential network is used for grounding, can prevent leakage, and further improve safety.

[0054] The present invention further provides a low-voltage electric floor heating system suitable for humid environments, including the packaged floor heating structure provided by the present invention and a low-voltage power supply device for providing a voltage of 2 to 58V, and the electric heating film in the packaged floor heating structure is electrically connected to the low-voltage power supply device.

[0055] In some preferred embodiments, the low voltage power supply device includes a transformer for converting a 220V municipal voltage into a 5-36V safety voltage.

[0056] In other preferred embodiments, the low-voltage electricity supply device includes a low-voltage solar power generation power source.

[0057] Preferably, the low-voltage electric floor heating system further comprises a first waterproof isolation layer arranged below the encapsulated floor heating structure, a concrete filling layer (preferably pebble concrete) arranged above the encapsulated floor heating structure in sequence, a second waterproof isolation layer and a finishing layer. The electric floor heating system is laid on the structural floor slab.

[0058] In some preferred embodiments, the low-voltage electric floor heating system further includes a thermostat and a wire pipe for regulating the heating temperature of the electric heating film.

[0059] In some preferred embodiments, the thickness of the finishing layer is 20 to 80 mm, and the material of the finishing layer includes but is not limited to flooring, ceramic tiles, marble, and the like.

[0060] Compared with the prior art, the present invention has the following technical effects:

[0061] The electric heating film provided by the present invention has excellent high temperature and high humidity resistance, strong adhesion between different layers, not easy to peel off, and can maintain a stable and ideal working state even in a humid working environment, and can solve the fire safety hazard caused by delamination and cracking of the electric heating film; the water-based conductive slurry adopts a combination of polyurethane resins that are the same as polyurethane resins but have different glass transition temperature characteristics as film-forming resins, on the one hand, so that the carbon film has excellent tensile strength and elongation at break, with a tensile strength of more than 50MPa and an elongation at break of less than 40%; on the other hand, by further combining the selection of a specific polyurethane resin, the square resistance of the prepared carbon film can be effectively reduced under the condition of the same conductive component, so that the carbon film can also have a high heating efficiency under low voltage conditions below 36V.

[0062] The encapsulated floor heating structure and low-voltage electric floor heating system provided by the present invention have both system safety and material durability, and can be truly suitable for use in humid environments. On the one hand, the transformer converts the municipal voltage into a safe voltage for the human body, and the electric floor heating system can be used normally under a safe voltage of 5 to 36V, fundamentally avoiding the risk of electric shock due to leakage, and will not cause harm to the human body. The comfort level is high and the system is safe. On the other hand, the use of the electric heating film of the present invention makes the electric floor heating system have stable working performance, a long service life in both dry and humid environments, is not easy to damage, the system is reliable, the materials are durable, and it is extremely practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for describing the embodiments.

[0064] Attached Figure 1 The infrared spectrum of the dispersing aid and its raw materials prepared in Example 3;

[0065] Attached Figure 2 This is a schematic diagram of the encapsulated floor heating structure in Example 4;

[0066] Attached Figure 3 This is a schematic diagram of the installation structure of the electric floor heating system in Example 4;

[0067] Attached Figure 4 This is a circuit diagram of the electric floor heating system in Example 4;

[0068] Among them: 100, structural floor; 200, wall; 300, ceiling;

[0069] 1. First waterproof isolation layer; 2. Encapsulated floor heating structure; 21. Reflective layer; 22. Insulation layer; 23. Electric heating film; 24. Protective layer; 25. Equipotential network; 3. Pebble concrete filling layer; 4. Second waterproof isolation layer; 5. Finishing layer; 61. Wire pipe; 62. Thermostat; 621. Temperature probe; 63. Transformer. DETAILED DESCRIPTION

[0070] For electric floor heating systems suitable for humid environments, they must first have extremely high safety performance to completely avoid the safety hazards of leakage and electric shock in high humidity environments; on this basis, the core heating component of the electric floor heating system, the electric heating film, is also required to have a heating effect and service life in a humid environment that is no less than that of traditional electric heating films used in dry environments. This requires the electric heating film to be resistant to high temperature and humidity, not easy to damage, can be used for a long time, be economical and environmentally friendly, and have high heating efficiency. However, there is no corresponding ideal solution in the prior art. The inventor of the present invention has improved the prior art through a large number of experimental studies and innovations, and proposed the solution of the present invention.

[0071] The basic concept of the present invention is to reduce the working voltage of the electric floor heating system to a human safety voltage below 36V through a transformer, fundamentally improve the system safety, and accordingly transform the electric heating film in the electric floor heating system to be suitable for use in low voltage and humid environments: improve the adhesion between the layers inside the electric heating film through adhesive materials to prevent the failure of peeling between different layers under high temperature and high humidity working environments; add hydrophobic additives to the raw materials of the carbon film to improve the waterproof performance of the carbon film and reduce the influence of environmental moisture on the function of the carbon film; organically combine the first polyurethane resin and the second polyurethane resin with different characteristics, wherein the first polyurethane resin has a lower glass transition temperature and is a flexible polyurethane resin; the second polyurethane resin has a higher glass transition temperature and is a hard polyurethane resin. The organic combination of the two polyurethane resins makes the carbon film have excellent mechanical properties such as tensile strength and elongation at break, which helps to improve the service life of the electric heating film, and makes the carbon film have excellent electrical conductivity. Compared with the prior art, the square resistance can be reduced, the electrical conductivity and heating efficiency can be improved under the same amount of conductive components, and it is suitable for use under low voltage conditions. For the same electrical conductivity, the amount of conductive components can be reduced, the cost can be reduced, and the process can be optimized.

[0072] Other inventive concepts of the present invention include using nano-carbon materials as the main conductive material, which has excellent conductive effect, uniform heat generation and high heat generation efficiency. Among them, the carbon film uses micro-nano-level linear carbon nanotubes as the main conductive component, which helps to enhance the mechanical properties of the carbon film, and at the same time, a certain amount of point-shaped conductive carbon black and flake graphite or graphene are compounded to further enhance its conductive properties and reduce square resistance.

[0073] Further inventive concepts of the present invention also include developing special dispersing aids for the carbon nanotube conductive components to effectively increase the dispersion of the carbon nanotubes, thereby improving process efficiency, reducing process costs, and improving product consistency while ensuring and improving the conductive properties of the electric heating film.

[0074] The present invention is further described below in conjunction with the examples. However, the present invention is not limited to the following examples. The implementation conditions used in the examples can be further adjusted according to the different requirements of specific use, and the implementation conditions not specified are conventional conditions in the industry.

[0075] Example 1

[0076] This embodiment provides an electric heating film suitable for a humid environment, which is prepared by the following method:

[0077] (1) Preparation of a dispersion of a conductive component

[0078] After mechanically stirring water and dispersant at 400 rpm for 10 min, carbon nanotubes, conductive carbon black and graphene were added, and stirred at a low speed of 600 rpm for 20 min in a high-speed disperser, then adjusted to a high speed of 1200 rpm and stirred for 30 min. During the high-speed stirring process, a defoamer (polyether-modified organic silicone emulsion BYK1724) was added dropwise at a rate of 50 g / min, and then introduced into a sand mill for turbine grinding at 2000 rpm for 90 min, and then the sand milling was stopped to obtain a uniform dispersion; after standing for defoaming, a dispersion of the conductive component was obtained for use.

[0079] Based on the total mass percentage of 100%, the dispersion of the conductive component is composed of: 12% carbon nanotubes, 3% conductive carbon black, 1.5% graphite powder, 1.5% graphene, 18% dispersant DISPERBYK2012, 0.3% defoaming agent and the balance water.

[0080] (2) Preparation of water-based conductive slurry

[0081] 40 g of the conductive component dispersion prepared in step (1), 8 g of Wanhua Chemical Crysol 6136 and 4 g of Wanhua Chemical Crysol 6140 were mixed, and dispersed at 600 rpm in a high-speed disperser for 30 min. Then, 0.03 g of thickener BYK425 and 1 g of waterproof wax additive Sanye XC-3206 were added, and mechanical stirring was carried out at 300 rpm for 10 min. After standing and defoaming, an aqueous conductive slurry was obtained.

[0082] (3) Making electric heating film

[0083] The silver paste prepared from the micron silver material is coated on the edge of the PET substrate (first substrate layer) with a polyurethane resin coating by a gravure process, with a width of 15 mm at both ends 55 mm away, and then the aqueous conductive paste prepared in step (2) is coated on the side of the first substrate layer coated with the silver paste by a micro-concave technique (coated between 62.5 mm on both sides from the edge of the first substrate layer, and part of the silver paste is covered on both sides), and maintained at 140°C for 10 minutes, and cured to form a film to form a carbon film and a silver electrode. During the heating and curing film formation process, the polyurethane resin pre-coating melts and bonds the PET substrate, the silver electrode, and the carbon film to each other. The cured silver electrode is partially exposed outside the carbon film on both sides, and the exposed silver electrode is further covered with a nickel-plated copper foil electrode material (12 mm wide on both sides at 47.5 mm from the edge of the first substrate layer) to complete the electrode production. At this time, the thickness, square resistance, adhesion, etc. of the carbon film can be tested. Then, a molten polyurethane glue (adhesive material) is further coated on one side of another PET substrate (second substrate layer), and then the side coated with the polyurethane glue is laid on the first substrate layer with electrodes and carbon films, and then placed at 30±2°C for 48 hours to obtain the electric heating film. At this time, the peel strength of the electric heating film can be tested, and accelerated life tests can be performed.

[0084] Example 2

[0085] This embodiment provides an electric heating film suitable for a humid environment. The preparation method of the electric heating film is basically the same as that of Embodiment 1, the main difference being that in this embodiment:

[0086] In step (1), the composition of the dispersion of the conductive component is as follows: 15% carbon nanotubes, 3% conductive carbon black, 18% dispersant DISPERBYK 2012, 0.3% defoaming agent and the balance water, calculated by total mass percentage as 100%;

[0087] In step (2), the raw materials of the aqueous conductive paste include 40 g of the conductive component dispersion prepared in step (1), 6 g of Wanhua Chemical Crysol 6136, and 6 g of Wanhua Chemical Crysol 6140.

[0088] Example 3

[0089] This embodiment provides an electric heating film suitable for a humid environment. The preparation method of the electric heating film is basically the same as that of the embodiment 1, except that in the step (1) of this embodiment, the composition of the dispersion of the conductive component is as follows: 18% carbon nanotubes, 16% dispersant DISPERBYK2012, 4% dispersing aid, 0.3% defoaming agent and the balance water, based on the total mass percentage of 100%. The specific preparation process of the dispersing aid is as follows:

[0090] 35 g of hydroxy hyperbranched polyester was added to a four-necked flask with a stirrer, a condenser, a thermometer and a nitrogen inlet, and dissolved in 300 mL of N, N-dimethylformamide. The mixture was heated to completely dissolve. Under the protection of nitrogen, a certain amount (the molar ratio of anhydride to hydroxy hyperbranched polyester was 5:1) of dodecenyl succinic anhydride and trimellitic anhydride (the molar ratio of dodecenyl succinic anhydride to trimellitic anhydride was 1:2) and 0.8 g of catalyst N, N-dimethylbenzylamine were added. After the mixture was dissolved, the temperature was raised to 110° C., and the mixture was reacted to a theoretical acid value (half of the initial acid value). After part of the solvent was evaporated, the reaction temperature was lowered to 50° C., and then the system was neutralized with a 30 wt % sodium hydroxide aqueous solution to a pH value of 7.0 to 8.0. Finally, a yellow transparent solution with a solid content of about 40% was obtained, i.e., a solution containing a dispersing aid, which was directly used for the preparation of a dispersion of a conductive component.

[0091] The hydroxyl hyperbranched polyester used is derived from Boltorn H20 from Perstorp, and its structure is as follows:

[0092]

[0093] The prepared dispersing aid and its raw materials were subjected to infrared detection, and the results were as follows: Figure 1 As shown, the results in the figure confirm that the dispersing aid was successfully prepared.

[0094] In this embodiment, the step (1) of preparing the dispersion of the conductive component is as follows:

[0095] Water, dispersing aid and dispersant were weighed according to the formula ratio, mechanically stirred at 400 rpm for 10 minutes, then carbon nanotubes were added, and stirred at a low speed of 600 rpm for 20 minutes in a high-speed disperser, then adjusted to a high speed of 1200 rpm and stirred for 30 minutes. During the high-speed stirring process, a defoamer (polyether-modified organic silicone emulsion BYK1724) was added dropwise at a rate of 50 g / min, and then introduced into a sand mill with a turbine grinding at 2000 rpm for 90 minutes, and then the sand grinding was stopped to obtain a uniform dispersion; after standing for defoaming, a carbon nanotube dispersion was obtained and set aside.

[0096] Then, an electric heating film was prepared according to steps (2) to (5) in Example 1.

[0097] The prepared dispersion was sampled for stability test (standing for 90 days). Before and after standing for 90 days, the carbon nanotubes were able to be stably and uniformly dispersed in water without agglomeration and precipitation.

[0098] When all the conductive components are carbon nanotubes, a hyperbranched polyester with a specific structure is used as a dispersing aid, and the use of the dispersant is coordinated. On the one hand, the dispersing aid is easily adsorbed on the surface of the carbon nanotubes, and on the other hand, the dispersing aid has a strong and lasting adsorption force on the pigment surface, and synergistically acts with the dispersant. When the carbon nanotube content is increased, the carbon nanotubes can still be stably and uniformly dispersed in water for a long time without agglomeration and precipitation, so that a high-solid content carbon nanotube dispersion can be obtained, and the dispersion also has the advantage of low viscosity. The aqueous conductive slurry prepared by the dispersion and the film made of the aqueous conductive slurry have uniform thickness, no shrinkage holes, good uniformity, and can achieve a uniform and stable conductive effect.

[0099] Comparative Example 1

[0100] This comparative example provides an electric heating film, and the preparation method of the electric heating film is basically the same as that of Example 1, the main difference being that no adhesive material is provided on the second substrate layer of the electric heating film in this comparative example.

[0101] Comparative Example 2

[0102] This comparative example provides an electric heating film, and the preparation method of the electric heating film is basically the same as that of Example 1, the main difference being that the waterproof wax additive Sanye XC-3206 is not added to the aqueous conductive slurry in this comparative example.

[0103] Comparative Example 3

[0104] This comparative example provides an electric heating film, the preparation method of which is basically the same as that of Example 1, with the main difference being that, when preparing the aqueous conductive slurry in step (2), Wanhua Chemical Crysol 6140 is used instead of Wanhua Chemical Crysol 6136, that is, only 12 g of a polyurethane resin dispersion Crysol 6140 is added.

[0105] Example 4

[0106] The present embodiment provides a packaged floor heating structure 2 suitable for a humid environment and a low-voltage electric floor heating system having the packaged floor heating structure 2 .

[0107] Among them, the structure of the encapsulated floor heating structure 2 is as follows Figure 2 As shown, it includes a reflective layer 21, an insulating layer 22, an electric heating film 23, a protective layer 24 and an equipotential network 25 laid in sequence from bottom to top, wherein the electric heating film 23 can adopt any one of the electric heating films in Examples 1 to 3, and the equipotential network 25 is used for grounding.

[0108] In this embodiment, the reflective layer 21 is a reflective film with a thickness of about 0.05 mm. The heat insulating layer 22 is an XPS insulation board with a thickness of about 20 mm. The protective layer 24 is a PE film with a thickness of about 0.05 mm. The equipotential net 25 is a galvanized steel wire mesh, which needs to be waterproofed.

[0109] See also Figure 3 and Figure 4 As shown, the low voltage electric floor heating system is constructed by the following methods:

[0110] (1) A first waterproof isolation layer 1 is laid on the structural floor 100, and then each layer structure of the encapsulated floor heating structure 2 is laid in sequence.

[0111] When laying the electric heating film 23, it is necessary to first draw the laying position line of the electric heating film 23 on the XPS insulation board, and then after laying the electric heating film 23 according to the position line, connect the wire harness and ensure that the joint is tightened.

[0112] The connected electric heating film 23 is connected to the load end of the thermostat 62 through the PC20 wire tube 61, and the L / N line is distinguished, wherein the PC20 wire tube 61 and part of the thermostat 62 can be buried in the wall 200; the external sensor line is connected to the temperature probe 621 of the thermostat 62.

[0113] On the other hand, the transformer 63 is fixed on the floor slab on the top of the ceiling 300, and the household line of the municipal power grid is connected to the input end of the transformer 63. The L / N lines need to be distinguished, and then the output end of the transformer 63 is connected to the power end of the thermostat 62 through the PC20 wire tube 61.

[0114] After completing the above circuit connection, the working condition of the electric heating film 23 is tested to confirm that it can generate heat normally. Then, the protective layer 24 and the equipotential network 25 in the encapsulated floor heating structure 2 are laid.

[0115] (2) Pebble concrete is laid on the surface of the encapsulated floor heating structure 2 to form a pebbled concrete filling layer 3 with a laying thickness of about 30 mm, and waterproofing treatment is performed.

[0116] (3) The dried pebbled concrete filling layer 3 is subjected to secondary waterproofing treatment to form a second waterproof isolation layer 4.

[0117] (4) Floor tiles are laid on the top layer to form a finishing layer 5, which has a thickness of about 40 mm, thereby completing the installation of the entire low-voltage electric floor heating system.

[0118] Performance test of the prepared carbon film and electric heating film

[0119] The carbon films of Examples 1 to 3 and Comparative Examples 1 to 3 were tested for thickness, sheet resistance and mechanical properties, and the results are shown in Table 1. The thickness of the carbon film was measured using a height gauge, and the sheet resistance of the carbon film was measured using a sheet resistance meter to measure the surface sheet resistance at different positions. The adhesion test was performed using a hundred-grid knife test, and the test method was based on the scratch test of ASTM D3359 paint and varnish.

[0120] After the electric heating film was boiled in water at 100°C for 8 hours, the peel strength before and after boiling was measured. The peel strength performance test refers to GB / T2792-2014 and JG / T286-2010.

[0121] The reference for the accelerated life test of electric heating film is GB / T 7287-2008 and JG / T 286-2010.

[0122] Table 1 Electric heating film performance test results

[0123]

[0124] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

[0125] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

Claims

1. An electric heating film suitable for a humid environment, the electric heating film comprising a substrate layer, a carbon film, and an electrode disposed between the substrate layer and the carbon film, characterized in that: An adhesive material for bonding the substrate layer, the carbon film and the electrode is also provided between the substrate layer and the carbon film. The carbon film is prepared by an aqueous conductive slurry, which contains a resin component, a conductive component and a hydrophobic additive. The resin component includes a first polyurethane resin with a glass transition temperature of ≤15°C and a second polyurethane resin with a glass transition temperature of ≥25°C.

2. The electric heating film suitable for humid environment according to claim 1, characterized in that: The substrate layer includes a first substrate layer and a second substrate layer, the carbon film is located between the first substrate layer and the second substrate layer, the electrode includes a first electrode portion combined with the carbon film and partially located between the carbon film and the first substrate layer, and a second electrode portion covered on a portion of the first electrode portion and located between the first electrode portion and the second substrate layer. The first substrate layer and the second substrate layer, the carbon film and the second substrate layer, and the electrode and the second substrate layer are all joined by an adhesive material. The first electrode portion and the second electrode portion use different electrode materials. The first substrate layer includes a substrate and a resin coating located on one side of the substrate. The carbon film is formed by coating the aqueous conductive slurry on the resin coating and curing it, and the first electrode portion is formed by coating the first electrode material on the resin coating and curing it.

3. The electric heating film suitable for humid environment according to claim 2, characterized in that: The adhesive material is a combination of one or more selected from polyurethane glue, epoxy resin glue, acrylic glue, and silicone glue; and / or, the resin coating is one or two selected from polyurethane resin and epoxy resin; and / or, the first electrode material is a silver material, and the electrode material of the second electrode part is nickel-plated copper foil; and / or, the hydrophobic additive is a combination of one or more selected from organic silicon compounds, paraffin emulsions, fluorine-containing low molecular weight resins, and aqueous dispersions of polytetrafluoroethylene modified wax; and / or, in terms of mass percentage, the hydrophobic additive accounts for 0.1% to 1% of the aqueous conductive paste.

4. The electric heating film suitable for humid environment according to claim 1, characterized in that: The mass ratio of the first polyurethane resin to the second polyurethane resin is less than 1; and / or the number average molecular weights of the first polyurethane resin and the second polyurethane resin are respectively ≥ 250,000, wherein the second polyurethane resin is a polyurethane resin prepared from a combination of one or more selected from isotolylene diisocyanate, xylene methane diisocyanate, xylylene diisocyanate, and dicyclohexylmethane diisocyanate as an isocyanate raw material.

5. The electric heating film suitable for humid environment according to claim 1, characterized in that: The mass ratio of the first polyurethane resin to the second polyurethane resin is 1:1-4.

6. The electric heating film suitable for humid environment according to claim 1, characterized in that: The mass ratio of the resin component to the conductive component is 1:1 to 4; and / or the conductive component is one or a combination of carbon nanotubes, graphene, graphite powder, and conductive carbon black; and / or, when preparing the aqueous conductive slurry, the conductive component is mixed with the resin component in the form of a dispersion, and the dispersion of the conductive component refers to a mixed liquid containing the conductive component, a dispersant and water and presenting a uniform flow dynamic as a whole.

7. The electric heating film suitable for humid environment according to claim 6, characterized in that: In the conductive component, the mass content of the carbon nanotubes is 60-100%. The dispersion of the conductive component further comprises a dispersing aid, which is a hyperbranched polyester having hydroxyl groups and carboxyl groups.

8. The electric heating film suitable for humid environments according to claim 6 or 7, characterized in that: The conductive component is a combination of carbon nanotubes, graphite powder, graphene and conductive carbon black. The conductive component is composed of 60-97% carbon nanotubes, 1-10% graphite powder, 1-10% graphene and 1-20% conductive carbon black in terms of mass percentage; and / or the dispersant is a copolymer containing pigment affinity groups; and / or the mass content of the conductive component in the dispersion of the conductive component is 1-20%.

9. A packaged floor heating structure, comprising an electric heating film, characterized in that: The electric heating film is as described in any one of claims 1 to 8.

10. The encapsulated floor heating structure according to claim 9, characterized in that: The packaged floor heating structure also includes an insulating layer and a reflective layer which are sequentially arranged below the electric heating film, and a protective layer and an equipotential network which are sequentially arranged above the electric heating film, and the equipotential network is used for grounding.

11. A low-voltage electric floor heating system suitable for a humid environment, comprising a packaged floor heating structure, characterized in that: The low-voltage electric floor heating system also includes a low-voltage power supply device for providing a voltage of 2 to 58 V. The encapsulated floor heating structure is as described in claim 9 or 10, and the electric heating film in the encapsulated floor heating structure is electrically connected to the low-voltage power supply device.

12. The low-voltage electric floor heating system suitable for humid environments according to claim 11, characterized in that: The low-voltage electric floor heating system also includes a first waterproof isolation layer arranged below the encapsulated floor heating structure and a concrete filling layer, a second waterproof isolation layer and a finishing layer arranged in sequence above the encapsulated floor heating structure.

13. The low-voltage electric floor heating system suitable for humid environments according to claim 11, characterized in that: The low-voltage power supply device is a low-voltage power supply device used to provide a voltage of 5 to 36V.

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