1. The composite graphene heating film with the flame retardant effect is characterized in that a first flame-retardant non-woven fabric layer, a graphene heating sheet layer and a second flame-retardant non-woven fabric layer are sequentially arranged on the composite graphene heating film from bottom to top; the graphene heating sheet layer is coated with graphene heating ink.

2. The composite graphene heating film with the flame retardant effect according to claim 1, wherein the graphene heating sheet layer is sequentially provided with a flexible circuit board, a PET intermediate layer and a PI bottom film from a lower layer to an upper layer, and the flexible circuit board, the PET intermediate layer and the PI bottom film are connected into a whole through a hot melt adhesive.

3. The composite graphene exothermic film with flame retardant effect according to claim 2, wherein the PET intermediate layer comprises a PET substrate, and the graphene exothermic ink is coated on the PET substrate.

4. The preparation method of the composite graphene exothermic film according to any one of claims 1 to 3, wherein the preparation method comprises the following steps:

s1 and preparation of graphene heating ink

Adding the solvent, the resin and the flame retardant into a stirring dispersion tank in sequence, dispersing for 10min, and setting the stirring speed to be 100-300r/min to obtain a first dispersion;

adding the graphene powder and the carbon black into the first dispersion body in sequence, dispersing in a stirring tank for 10-30min, and setting the stirring speed to be 100 plus materials at 500r/min to obtain a second dispersion body;

adding an auxiliary agent into the second dispersion, and performing dispersion stirring in a stirring tank for 20-60min at a stirring speed of 1000-1200r/min to obtain a third dispersion;

placing the third dispersion into a three-roll grinder, grinding and stirring for 30min, and setting the stirring speed to be 1000-;

s2 and preparation of graphene heating sheet layer

Uniformly coating the graphene heating ink prepared in the step S1 on a PET substrate to form a PET intermediate layer;

sequentially stacking a flexible circuit board, a PET middle layer and a PI bottom film from bottom to top, and compounding into a graphene heating sheet layer through hot pressing of a hot press; the temperature of the hot-pressing compounding is 60-160 ℃;

s3 preparation of composite graphene heating film

And (3) stacking the first flame-retardant non-woven fabric layer, the graphene heating sheet layer and the second flame-retardant non-woven fabric layer from bottom to top in sequence, performing hot press molding through a hot press, and then slitting to obtain the composite graphene heating film.

5. The method for preparing a composite graphene exothermic film according to claim 4, wherein in step S1, the graphene powder is a nano-powder, and the number of layers is less than 10;

the resin is one or more of acrylic resin, polyurethane resin, epoxy resin, phenolic resin and polyamide resin;

the solvent is one or more of deionized water, ethanol, N-methyl pyrrolidone and tetrahydrofuran;

the flame retardant is one or more of halogen-free organic phosphorus flame retardants or halogen-free inorganic flame retardants;

the auxiliary agent is one or more of a dispersing agent, a thickening agent, a defoaming agent and a flatting agent.

6. The method for preparing a composite graphene exothermic film according to claim 5, wherein in step S1, the particle size of the graphene powder is 20-80nm, and the number of layers is less than 8;

the halogen-free organic phosphorus flame retardant comprises one or more of phosphate, phosphite and organic phosphorus salt; the halogen-free inorganic flame retardant comprises one or more of antimony trioxide, silicon flame retardants, ammonium polyphosphate, aluminum hydroxide, magnesium hydroxide and red phosphorus.

7. The preparation method of the composite graphene exothermic film according to claim 4, wherein in step S1, the raw materials for preparing the graphene exothermic ink are prepared according to the following parts by weight: 1-4 parts of graphene powder, 30-55 parts of resin, 10-15 parts of flame retardant, 40-50 parts of solvent, 1-4 parts of carbon black and 3-7 parts of auxiliary agent.

8. The method for preparing a composite graphene exothermic film according to claim 4, wherein in step S2, the method for preparing the flexible circuit board is as follows:

compounding the PI copper-clad film and the photosensitive film to obtain a first composite membrane; the laminating machine for compounding is of a precoating type, and can be used for carrying out one-time hot press forming on a PI copper-clad film and a photosensitive film, wherein the hot press temperature is set to be 100-160 ℃ during laminating;

exposing the first composite membrane and the film, and generating a latent image of an electrode pattern on the surface of a photosensitive film of the first composite membrane to obtain a second composite membrane;

the second composite membrane is processed by a developing process, and the latent image can be converted into a visible image to obtain a third composite membrane;

cleaning and drying the third composite membrane, and then removing a protective film of a region to be etched through an etching process to generate a designed electrode pattern to obtain a fourth composite membrane;

and cleaning and drying the fourth composite membrane, and then removing the membrane to remove the protective membrane in the non-etched area, thus obtaining the flexible circuit board.

9. The method for preparing a composite graphene exothermic film according to claim 4, wherein in step S3, the first flame-retardant non-woven fabric layer and the first flame-retardant non-woven fabric layer are prepared by a saturated impregnation method or a foam impregnation method;

the saturated impregnation method is specifically as follows:

preparing mixed polyester fiber from polyethylene glycol terephthalate powder through spinning;

blending the mixed polyester fiber and the additional fiber to prepare non-woven fabric fiber, and opening and carding the non-woven fabric fiber to form a non-woven fabric fiber net; wherein the mass ratio of the mixed polyester fiber to the additional fiber is as follows: 86-92 parts of mixed polyester fiber and 8-14 parts of additional fiber;

the non-woven fabric fiber web is pulled by a conveyer belt to sequentially pass through a dipping tank filled with acrylate adhesives and a roller, the pulling speed of the conveyer belt is 30-40 m/min, and the pressure of the roller acting on the non-woven fabric fiber web is 50-55 Pa;

the rolled non-woven fabric fiber web enters an oven for drying, the temperature of the oven is 250-260 degrees, the speed of the non-woven fabric fiber web passing through the oven is 30-40 m/min, and 15-120 g/m is prepared²The impregnated non-woven fabric is trimmed, wound and packaged to obtain a flame-retardant non-woven fabric layer;

the foam impregnation method is specifically as follows:

uniformly stirring the spinning stock solution of the viscose fibers by a stirrer to obtain mixed spinning stock solution, and then carrying out wet spinning on the mixed spinning stock solution to prepare the viscose fibers;

the viscose fiber and the additional fiber are opened, mixed and carded to form a non-woven fabric fiber net, and the multifunctional viscose fiber and the additional fiber are mixed according to the mass ratio of: viscose fiber: 80-90 parts of additional fiber: 10-20 parts of additional polyester fiber;

dispersing the flame retardant, the waterproof auxiliary agent and the acrylate adhesive in stirring dispersion equipment according to the ratio of 1:1:5, setting the stirring speed to be 300-500rmp, and setting the stirring dispersion time to be 10 min;

uniformly spraying the prepared foam adhesive on a non-woven fabric fiber net in a spraying mode;

the non-woven fabric fiber web is vibrated up and down, so that the foam adhesive can quickly and uniformly permeate into the non-woven fabric fiber web, the vibration amplitude is 12-16 mm, and the vibration frequency is 220-320 times/min;

the non-woven fabric fiber web after vibration treatment enters an oven to be dried, wherein the temperature of the oven is 240 ℃, and the speed of the non-woven fabric fiber web passing through the oven is 35 m/min; obtaining 60-80g/m²The foam-impregnated nonwoven fabric of (1);

and cutting edges of the prepared non-woven fabric, winding and packaging.

10. The method for preparing a composite graphene exothermic film according to claim 4, wherein in step S3, the temperature of the hot press molding is 100-270 ℃, the time is 1-10S, and the pressure is 30-55 MPa.

Background

For the heating film, various technical index requirements can be continuously added along with the expansion of the application field of the heating film, and for some application scenes, such as a preheating component of a new energy electric automobile power battery, the flame retardance of the heating film is required to reach VO level as one of core technical requirements. Most of the existing developed graphene heating films are formed by compounding a layer of flame retardant material between structural layers of the graphene heating film or simply performing flame retardant modification on non-woven fabrics, so that the risk of heating film combustion caused by overhigh external environment temperature is avoided.

The processing technologies are difficult to avoid the combustion risk of the graphene heating sheet layer caused by overhigh internal temperature.

Disclosure of Invention

Therefore, the invention provides a composite graphene heating film with a flame retardant effect and a preparation process thereof, and aims to solve the problem that most of the existing graphene heating films are formed by compounding a layer of flame retardant material between structural layers of the graphene heating film or simply performing flame retardant modification on non-woven fabrics, so that the combustion risk of the graphene heating sheet layer caused by overhigh internal temperature is difficult to avoid.

In order to achieve the above purpose, the invention provides the following technical scheme:

according to the first aspect of the invention, the composite graphene heating film with the flame retardant effect is provided with a first flame-retardant non-woven fabric layer, a graphene heating sheet layer and a second flame-retardant non-woven fabric layer from bottom to top in sequence; the graphene heating sheet layer is coated with graphene heating ink.

Further, the graphene heating sheet layer is sequentially provided with a flexible circuit board, a PET (polyethylene terephthalate) middle layer and a PI (polyimide) bottom film from the lower layer to the upper layer, and the flexible circuit board, the PET middle layer and the PI bottom film are connected into a whole through a hot melt adhesive.

Further, the PET intermediate layer comprises a PET substrate, and the graphene heating ink is coated on the PET substrate. Further, the coating layer of the graphene exothermic ink on the PET substrate can be prepared by coating with a coater, screen printing, casting, and the like.

According to the invention, the graphene heating ink with the flame-retardant effect is directly compounded in the graphene heating sheet layer, so that the graphene heating sheet layer can reach the flame-retardant effect of V0 level, the graphene heating sheet layer with the flame-retardant effect is matched with the first flame-retardant non-woven fabric layer and the second flame-retardant non-woven fabric layer with the flame-retardant effect of V0 level to prepare the composite graphene heating film, so that the inner part and the outer part of the composite graphene heating film both reach the flame-retardant requirement of V0 level, the combustion phenomenon caused by overhigh internal factors and external environment temperature of the composite graphene heating film can be effectively avoided, and the composite graphene heating film is suitable for scenes with strict requirements on the flame retardance of materials.

According to a second aspect of the present invention, the preparation method of the composite graphene heating film includes the following steps:

s1 and preparation of graphene heating ink

Adding the solvent, the resin and the flame retardant into a stirring dispersion tank in sequence, dispersing for 10min, and setting the stirring speed to be 100-300r/min to obtain a first dispersion;

adding the graphene powder and the carbon black into the first dispersion body in sequence, dispersing in a stirring tank for 10-30min, and setting the stirring speed to be 100 plus materials at 500r/min to obtain a second dispersion body;

adding an auxiliary agent into the second dispersion, and performing dispersion stirring in a stirring tank for 20-60min at a stirring speed of 1000-1200r/min to obtain a third dispersion;

placing the third dispersion into a three-roll grinder, grinding and stirring for 30min, and setting the stirring speed to be 1000-;

s2 and preparation of graphene heating sheet layer

Uniformly coating the graphene heating ink prepared in the step S1 on a PET substrate to form a PET intermediate layer;

sequentially stacking a flexible circuit board, a PET middle layer and a PI bottom film from bottom to top, and compounding into a graphene heating sheet layer through hot pressing of a hot press; the temperature of the hot-pressing compounding is 60-160 ℃;

s3 preparation of composite graphene heating film

And (3) stacking the first flame-retardant non-woven fabric layer, the graphene heating sheet layer and the second flame-retardant non-woven fabric layer from bottom to top in sequence, performing hot press molding through a hot press, and then slitting to obtain the composite graphene heating film.

Further, in step S1, the graphene powder is a nano-powder, and the number of layers is less than 10;

the resin is one or more of acrylic resin, polyurethane resin, epoxy resin, phenolic resin and polyamide resin;

the solvent is one or more of deionized water, ethanol, N-methyl pyrrolidone and tetrahydrofuran;

the flame retardant is one or more of halogen-free organic phosphorus flame retardants or halogen-free inorganic flame retardants;

the auxiliary agent is one or more of a dispersing agent, a thickening agent, a defoaming agent and a flatting agent.

Further, in step S1, the particle size of the graphene powder is 20-80nm, and the number of layers is less than 8;

the halogen-free organic phosphorus flame retardant comprises one or more of phosphate, phosphite and organic phosphorus salt; the halogen-free inorganic flame retardant comprises one or more of antimony trioxide, silicon flame retardants, ammonium polyphosphate, aluminum hydroxide, magnesium hydroxide and red phosphorus.

Through the technical scheme, the halogen-free flame retardant is selected as the flame retardant, so that the pollution of the electrolyte caused by the migration of halogen ions under the condition of long-term use can be prevented, and certain advantages are realized for specific application scenes, such as the application of the halogen-free flame retardant as a preheating film of a power battery, and the pollution of the electrolyte cannot be caused.

Further, the graphene heating ink is prepared from the following raw materials in parts by weight: 1-4 parts of graphene powder, 30-55 parts of resin, 10-15 parts of flame retardant, 40-50 parts of solvent, 1-4 parts of carbon black and 3-7 parts of auxiliary agent.

Further, the preparation method of the flexible circuit board comprises the following steps:

compounding the PI copper-clad film and the photosensitive film to obtain a first composite membrane; the laminating machine for compounding is of a precoating type, and can be used for carrying out one-time hot press forming on a PI copper-clad film and a photosensitive film, wherein the hot press temperature is set to be 100-160 ℃ during laminating;

exposing the first composite membrane and the film, and generating a latent image of an electrode pattern on the surface of a photosensitive film of the first composite membrane to obtain a second composite membrane;

the second composite membrane is processed by a developing process, and the latent image can be converted into a visible image to obtain a third composite membrane;

cleaning and drying the third composite membrane, and then removing a protective film of a region to be etched through an etching process to generate a designed electrode pattern to obtain a fourth composite membrane;

and cleaning and drying the fourth composite membrane, and then removing the membrane to remove the protective membrane in the non-etched area, thus obtaining the flexible circuit board.

Further, the first flame-retardant non-woven fabric layer and the first flame-retardant non-woven fabric layer are prepared by a saturated dipping method or a foam dipping method;

the saturated impregnation method is specifically as follows:

preparing mixed polyester fiber from polyethylene glycol terephthalate powder through spinning;

blending the mixed polyester fiber and the additional fiber to prepare non-woven fabric fiber, and opening and carding the non-woven fabric fiber to form a non-woven fabric fiber net; wherein the mass ratio of the mixed polyester fiber to the additional fiber is as follows: 86-92 parts of mixed polyester fiber and 8-14 parts of additional fiber;

the non-woven fabric fiber web is pulled by a conveyer belt to sequentially pass through a dipping tank filled with acrylate adhesives and a roller, the pulling speed of the conveyer belt is 30-40 m/min, and the pressure of the roller acting on the non-woven fabric fiber web is 50-55 Pa;

the rolled non-woven fabric fiber web enters an oven for drying, the temperature of the oven is 250-260 degrees, the speed of the non-woven fabric fiber web passing through the oven is 30-40 m/min, and 15-120 g/m is prepared²The impregnated non-woven fabric is trimmed, wound and packaged to obtain a flame-retardant non-woven fabric layer;

the foam impregnation method is specifically as follows:

uniformly stirring the spinning stock solution of the viscose fibers by a stirrer to obtain mixed spinning stock solution, and then carrying out wet spinning on the mixed spinning stock solution to prepare the viscose fibers;

the viscose fiber and the additional fiber are opened, mixed and carded to form a non-woven fabric fiber net, and the multifunctional viscose fiber and the additional fiber are mixed according to the mass ratio of: viscose fiber: 80-90 parts of additional fiber: 10-20 parts of additional polyester fiber;

dispersing the flame retardant, the waterproof auxiliary agent and the acrylate adhesive in stirring dispersion equipment according to the ratio of 1:1:5, setting the stirring speed to be 300-500rmp, and setting the stirring dispersion time to be 10 min;

uniformly spraying the prepared foam adhesive on a non-woven fabric fiber net in a spraying mode;

the non-woven fabric fiber web is vibrated up and down, so that the foam adhesive can quickly and uniformly permeate into the non-woven fabric fiber web, the vibration amplitude is 12-16 mm, and the vibration frequency is 220-320 times/min;

the non-woven fabric fiber web after vibration treatment enters an oven to be dried, wherein the temperature of the oven is 240 ℃, and the speed of the non-woven fabric fiber web passing through the oven is 35 m/min; obtaining 60-80g/m²The foam-impregnated nonwoven fabric of (1);

and cutting edges of the prepared non-woven fabric, winding and packaging.

Through the technical scheme, the flame-retardant non-woven fabric layer with the waterproof and flame-retardant effects can be prepared. The flame retardant adopted in the dipping process is a phosphorus flame retardant to achieve the flame retardant effect after the non-woven fabric is dipped, and the flame retardant grade requires V0 grade. Meanwhile, the adopted flame retardant does not contain halogen, so that the pollution of the electrolyte caused by the migration of halogen ions under the condition of long-term use can be prevented, and the flame retardant has certain advantages for specific application scenes, such as a preheating film of a power battery, and the pollution of the electrolyte cannot be caused.

Further, in step S3, the temperature of the hot press forming is 100-270 ℃, the time is 1-10S, and the pressure is 30-55 MPa.

The invention has the following advantages:

each structural layer of the composite graphene heating film with the flame retardant effect has the V0-level flame retardant effect, the combustion phenomenon of the composite graphene heating film caused by internal factors and overhigh external environment temperature can be effectively avoided, and the composite graphene heating film is suitable for scenes with strict requirements on the flame retardance of materials.

The composite graphene heating film with the flame retardant effect also has the effects of water resistance, high strength, good high temperature resistance, aging resistance, high elongation, good stability and air permeability and corrosion resistance.

According to the preparation method of the composite graphene heating film with the flame retardant effect, the graphene heating ink with the flame retardant effect is directly compounded in the graphene heating sheet layer, so that the graphene heating sheet layer can achieve the flame retardant effect of V0 level, and then the graphene heating sheet layer with the flame retardant effect is matched with the first flame-retardant non-woven fabric layer and the second flame-retardant non-woven fabric layer with the flame retardant effect of V0 level to prepare the composite graphene heating film, so that the inner part and the outer part of the composite graphene heating film can achieve the flame retardant requirement of V0 level.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below. It should be apparent that the drawings in the following description are merely exemplary, and that other embodiments can be derived from the drawings provided by those of ordinary skill in the art without inventive effort.

The structures, ratios, sizes, and the like shown in the present specification are only used for matching with the contents disclosed in the specification, so that those skilled in the art can understand and read the present invention, and do not limit the conditions for implementing the present invention, so that the present invention has no technical significance, and any structural modifications, changes in the ratio relationship, or adjustments of the sizes, without affecting the functions and purposes of the present invention, should still fall within the scope of the present invention.

Fig. 1 is a flow chart of a preparation process of a graphene heating sheet layer provided in embodiment 2 of the present invention;

fig. 2 is a flowchart of a preparation process of the composite graphene heating film provided in embodiment 2 of the present invention.

Detailed Description

The present invention is described in terms of particular embodiments, other advantages and features of the invention will become apparent to those skilled in the art from the following disclosure, and it is to be understood that the described embodiments are merely exemplary of the invention and that it is not intended to limit the invention to the particular embodiments disclosed. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

A composite graphene heating film with a flame-retardant effect is sequentially provided with a first flame-retardant non-woven fabric layer, a graphene heating sheet layer and a second flame-retardant non-woven fabric layer from bottom to top; the graphene heating sheet layer is sequentially provided with a flexible circuit board, a PET (polyethylene terephthalate) middle layer and a PI bottom film from the lower layer to the upper layer, and the flexible circuit board, the PET middle layer and the PI bottom film are connected into a whole through hot melt adhesive; the PET intermediate level includes the PET base plate, it has to coat on the PET base plate graphite alkene heating ink.

Example 2

The preparation method of the composite graphene heating film with the flame retardant effect in embodiment 1 comprises the following steps:

s1 and preparation of graphene heating ink

Preparing raw materials in parts by weight as follows: 3 parts of graphene powder, 40 parts of resin, 12 parts of a flame retardant, 45 parts of water, 3 parts of carbon black, 2 parts of a dispersing agent, 1 part of a defoaming agent, 1 part of a thickening agent and 1 part of a flatting agent, wherein the flame retardant is a phosphate flame retardant.

The graphene powder is few-layer graphene (1-3 layers), is purchased from Xianan graphene technology of Xiana of Xiamen, Inc., and is KNG-G2-3 graphene powder (hydrophilic), is produced by adopting a mechanical stripping method, keeps the electric and heat conducting performance of the graphene to the maximum extent, and has a graphene single-layer rate of more than 90%.

The resin is waterborne polyurethane resin which plays a role of film formation after being cured, has the model number of 1926 and is purchased from Jitian chemical industry Co., Ltd.

The solvent is deionized water, mainly used for dissolving polyurethane resin and dispersing graphene powder, and is self-made by a water purifier in a laboratory.

The flame retardant is phosphate flame retardant, has good compatibility with polyurethane, and is purchased from Doher-601 model of Daorhijie New Material science and technology Co.

The thickener mainly has the function of improving the viscosity of the graphene heating ink in a formula system so as to facilitate subsequent printing and coating, and is purchased from new materials, Inc. of south China, Guangdong province, and model L-2001.

The defoaming agent is an organic modified polysiloxane oil defoaming agent, has the effects of inhibiting, defoaming and defoaming in an ink system, and is purchased from Defeng defoaming agent Co., Ltd, Dongguan, and has the model DF-2416.

The leveling agent is polyether modified siloxane, can be generally used as a smoothing and flowing aid for water-based, radiation curing and solvent-based coating systems, and is purchased from New Material Yongchu, Foshan, model MT-307.

Adding water, polyurethane resin and a flame retardant into a stirring dispersion tank in sequence, dispersing for 10min, and setting the stirring speed to be 100-300r/min to obtain a first dispersion;

adding the graphene powder and the carbon black into the first dispersion body in sequence, dispersing in a stirring tank for 10-30min, and setting the stirring speed to be 100 plus materials at 500r/min to obtain a second dispersion body;

adding a dispersing agent into the second dispersion, dispersing and stirring in a stirring tank for 30min, setting the stirring speed to be 1000-;

placing the third dispersion into a three-roll grinder, grinding and stirring for 30min, and setting the stirring speed to be 1000-; the prepared graphene heating ink is measured by a scraper fineness meter, and the fineness of the graphene heating ink is 3-5 mu m.

S2, preparing the graphene heating sheet layer, wherein the flow chart of the preparation process is shown in figure 1.

Uniformly coating the graphene heating ink prepared in the step S1 on a PET substrate to form a PET intermediate layer;

compounding the PI copper-clad film and the photosensitive film to obtain a first composite membrane; the laminating machine for compounding is of a precoating type, and can be used for carrying out one-time hot press forming on a PI copper-clad film and a photosensitive film, wherein the hot press temperature is set to be 100-160 ℃ during laminating;

exposing the first composite membrane and the film, and generating a latent image of an electrode pattern on the surface of a photosensitive film of the first composite membrane to obtain a second composite membrane;

the second composite membrane is processed by a developing process, and the latent image can be converted into a visible image to obtain a third composite membrane;

cleaning and drying the third composite membrane, and then removing a protective film of a region to be etched through an etching process to generate a designed electrode pattern to obtain a fourth composite membrane;

and cleaning and drying the fourth composite membrane, and then removing the membrane to remove the protective membrane in the non-etched area, thereby preparing the flexible circuit board.

Sequentially stacking a flexible circuit board, a PET middle layer and a PI bottom film from bottom to top, and compounding into a graphene heating sheet layer through hot pressing of a hot press; the temperature of the hot-pressing compounding is 60-160 ℃;

s3, preparing the composite graphene heating film, wherein a flow chart of a preparation process of the composite graphene heating film is shown in FIG. 2.

Firstly, preparing a flame-retardant non-woven fabric layer by adopting a saturated dipping method production process:

preparing the polyethylene glycol terephthalate powder into mixed polyester fibers by spinning;

blending the mixed polyester fiber and the additional fiber to prepare non-woven fabric fiber, and opening and carding the non-woven fabric fiber to form a non-woven fabric fiber net; wherein the mass ratio of the mixed polyester fiber to the additional fiber is as follows: 86-92 parts of mixed polyester fiber and 8-14 parts of additional fiber;

the non-woven fabric fiber web is pulled by a conveyer belt to sequentially pass through a dipping tank filled with acrylate adhesives and a roller, the pulling speed of the conveyer belt is 30-40 m/min, and the pressure of the roller acting on the non-woven fabric fiber web is 50-55 Pa;

the rolled non-woven fabric fiber web enters an oven for drying, the temperature of the oven is 250-260 degrees, the speed of the non-woven fabric fiber web passing through the oven is 30-40 m/min, and 15-120 g/m is prepared²The non-woven fabric is dipped, and then the edge cutting, the winding and the packaging are carried out to obtain the flame-retardant non-woven fabric layer.

And (3) stacking the first flame-retardant non-woven fabric layer, the graphene heating sheet layer and the second flame-retardant non-woven fabric layer from bottom to top in sequence, carrying out hot-press molding through a hot press at the temperature of 100-270 ℃, the time of 1-10s and the pressure of 30-55Mpa, and then slitting to obtain the composite graphene heating film.

Example 3

The preparation method of the composite graphene heating film with the flame retardant effect is the same as that of the embodiment 2 except that the following technical scheme is different from that of the embodiment 2:

in step S1, the raw materials are prepared in the following weight parts: the flame retardant is prepared from the following raw materials, by weight, 1 part of graphene powder, 30 parts of resin, 10 parts of a flame retardant, 40 parts of water, 1 part of carbon black, 1 part of a dispersing agent, 0.5 part of a defoaming agent, 1 part of a thickening agent and 0.5 part of a flatting agent, wherein the flame retardant is an antimony trioxide flame retardant, and the resin is acrylic resin.

Example 4

The preparation method of the composite graphene heating film with the flame retardant effect is the same as that of the embodiment 2 except that the following technical scheme is different from that of the embodiment 2:

in step S1, the raw materials are prepared in the following weight parts: 4 parts of graphene powder, 55 parts of resin, 15 parts of flame retardant, 50 parts of water, 4 parts of carbon black, 3 parts of dispersing agent, 1.5 parts of defoaming agent, 1.5 parts of thickening agent and 1 part of flatting agent, wherein the flame retardant is phosphite flame retardant, and the resin is epoxy resin.

Example 5

The preparation method of the composite graphene heating film with the flame retardant effect is the same as that of the embodiment 2 except that the following technical scheme is different from that of the embodiment 2:

in step S3, the flame-retardant nonwoven fabric layer is prepared by a foam impregnation method, i.e., a chemical agent (generally an adhesive) is used to generate a large amount of foam in an impregnation tank to coat on a fiber web carded into a web, so as to achieve the purpose of fixing the fibers, and then the fiber web is processed and formed by a subsequent hot-pressing process, which specifically comprises the following steps:

uniformly stirring the spinning stock solution of the viscose fibers by a stirrer to obtain mixed spinning stock solution, and then carrying out wet spinning on the mixed spinning stock solution to prepare the viscose fibers;

the viscose fiber and the additional fiber are opened, mixed and carded to form a non-woven fabric fiber net, and the multifunctional viscose fiber and the additional fiber are mixed according to the mass ratio of: viscose fiber: 85 parts of additional fibers: 15 parts of additional polyester fiber;

dispersing the flame retardant, the waterproof auxiliary agent and the acrylate adhesive in stirring dispersion equipment according to the ratio of 1:1:5, setting the stirring speed to be 300-500rmp, and setting the stirring dispersion time to be 10 min;

uniformly spraying the prepared foam adhesive on a non-woven fabric fiber net in a spraying mode;

the non-woven fabric fiber web is vibrated up and down, so that the foam adhesive can quickly and uniformly permeate into the non-woven fabric fiber web, the vibration amplitude is 12-16 mm, and the vibration frequency is 220-320 times/min;

the non-woven fabric fiber web after vibration treatment enters an oven for drying, and the temperature of the oven is 240 DEG CThe speed of the non-woven fabric fiber web passing through the oven is 35 m/min; to obtain 70g/m²The foam-impregnated nonwoven fabric of (1);

and cutting edges of the prepared non-woven fabric, winding and packaging.

Examples of the experiments

The graphene heating sheet layer prepared in step S2, the first flame-retardant non-woven fabric layer prepared in step S3, and the composite graphene heating film prepared in step S3 in example 2 were subjected to a vertical method combustion test under the sample treatment conditions required by GB/T2408-2008, and the test results are recorded in the following tables 1, 2, and 3, respectively:

remarking: the total after flame time of the sample strip by the vertical combustion method is calculated as the following formula 1:

table 1 graphene heating sheet layer sample vertical method combustion test experimental data

According to the experimental data of the vertical combustion test of the graphene heating sheet layer sample in the table 1, the flame retardant property of the prepared graphene heating sheet layer can reach UL94V-0 level.

TABLE 2 vertical Combustion test data of the first flame-retardant nonwoven layer sample

According to the experimental data of the vertical burning test of the first flame-retardant non-woven fabric layer sample in the table 2, the flame retardant property of the flame-retardant non-woven fabric layer of the invention can be seen to reach UL94V-0 grade.

Table 3 composite graphene heating film sample vertical combustion test experimental data

According to the experimental data of the vertical combustion test of the composite graphene heating film sample in table 3, it can be seen that the flame retardant property of the composite graphene heating film prepared by the preparation method provided by the invention reaches UL94V-0 level.

Although the invention has been described in detail above with reference to a general description and specific examples, it will be apparent to one skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.