阅读说明：本技术 非织造布以及电磁屏蔽膜 (Nonwoven fabric and electromagnetic shielding film ) 是由 陈莉 林陆菁 于 2021-09-02 设计创作，主要内容包括：本申请涉及非织造布材料领域,涉及一种非织造布以及电磁屏蔽膜。该非织造布,包括：有机主干纤维、无机主干纤维以及粘结纤维；以质量百分比计,有机主干纤维的占比为20％～75％,无机主干纤维的占比不高于35％,粘结纤维的占比为25％～45％；有机主干纤维的纤维直径不大于4μm；无机主干纤维的纤维直径不大于6μm；粘结纤维的纤维直径不大于10μm。通过限定纤维配比,保证了非织造布内部纤维之间的充分粘连固合,形成了紧致的网状结构,固合定型效果好,保证了非织造布的机械强度。通过限定纤维直径能够保证非织造布的厚度较薄。从而实现了在提高机械强度的同时减少非织造布的纤维层数,得到厚度薄、机械强度高的非织造布。(The application relates to the field of non-woven fabric materials, in particular to non-woven fabric and an electromagnetic shielding film. The non-woven fabric comprises: organic trunk fibers, inorganic trunk fibers, and binder fibers; the mass percentage of the organic main fiber is 20-75%, the mass percentage of the inorganic main fiber is not higher than 35%, and the mass percentage of the bonding fiber is 25-45%; the fiber diameter of the organic trunk fiber is not more than 4 μm; the fiber diameter of the inorganic main fiber is not more than 6 μm; the fiber diameter of the binder fiber is not more than 10 μm. By limiting the fiber proportion, the full adhesion and the fixation among fibers in the non-woven fabric are ensured, a compact net-shaped structure is formed, the fixation and shaping effects are good, and the mechanical strength of the non-woven fabric is ensured. The thickness of the nonwoven fabric can be ensured to be thin by limiting the fiber diameter. Therefore, the mechanical strength is improved, the fiber layer number of the non-woven fabric is reduced, and the non-woven fabric with thin thickness and high mechanical strength is obtained.)

1. A nonwoven fabric, comprising: organic trunk fibers, inorganic trunk fibers, and binder fibers; the mass percentage of the organic main fiber is 20-75%, the mass percentage of the inorganic main fiber is not higher than 35%, and the mass percentage of the bonding fiber is 25-45%; the fiber diameter of the organic trunk fiber is not more than 4 μm; the fiber diameter of the inorganic main fiber is not more than 6 μm; the fiber diameter of the binding fiber is not more than 10 μm.

2. A nonwoven fabric according to claim 1,

the melting point or softening point of the bonding fiber is 100-250 ℃; the melting point or softening point of the organic trunk fiber is higher than that of the binding fiber by not less than 20 ℃.

3. A nonwoven fabric according to claim 1,

the fiber lengths of the organic trunk fiber, the inorganic trunk fiber and the bonding fiber are all in the range of 1 mm-6 mm.

4. A nonwoven according to any of claims 1-3,

the longitudinal tensile strength of the non-woven fabric is within the range of 2.5N/15 mm-66N/15 m; the transverse tensile strength of the non-woven fabric is within the range of 2.0N/15 mm-45N/15 mm.

5. A nonwoven according to any of claims 1-3,

the thickness of the non-woven fabric is within the range of 5-30 mu m.

6. A nonwoven according to any of claims 1-3,

the density of the non-woven fabric is 0.10g/m³～0.50g/m³Within the range;

optionally, the nonwoven fabric has an average pore size of not greater than 5.0mm and a ratio of maximum pore size to average pore size of not less than 1 and not greater than 10.

7. A nonwoven fabric according to claim 1,

the inorganic trunk fiber includes: alumina silicate fibers, mullite fibers, forsterite fibers, alumina fibers, quartz fibers, zirconia fibers, SiO₂CaO-MgO based fiber and Al₂O₃CaO-based fiber, Al₂O₃-SiO₂-ZrO₂At least one of a fiber, a boride fiber, a carbide fiber, a nitride fiber, or a glass fiber;

optionally, the boride fibers comprise zirconium boride fibers;

optionally, the carbide fibers comprise silicon carbide fibers;

optionally, the nitride fibers comprise silicon nitride fibers or boron nitride fibers;

optionally, the glass fibers comprise magnesium aluminum silicon ternary glass fibers, magnesium aluminum silicon glass fibers, or silicon aluminum calcium magnesium glass fibers.

8. A nonwoven fabric according to claim 2,

the organic trunk fiber includes: at least one of polyolefin fiber, polyamide fiber, polyimide fiber, polytetrafluoroethylene fiber, polyvinyl alcohol fiber, polyvinylidene fluoride fiber, polyphenylene sulfide fiber, polyether ether ketone fiber, polyacrylonitrile fiber, polycarbonate fiber, or aramid fiber;

optionally, the polyamide fibers comprise polyethylene terephthalate fibers, polybutylene terephthalate fibers;

optionally, the polyolefin fibers comprise polyethylene fibers, polypropylene fibers, polyvinyl chloride fibers, ES fibers.

9. A nonwoven fabric according to claim 2,

the binding fiber comprises: at least one of polyethylene terephthalate undrawn fiber, polybutylene terephthalate undrawn fiber, polyolefin fiber, or sheath-core structure composite fiber as a sheath material;

optionally, the polyolefin fibers comprise polyethylene fibers, polypropylene fibers, or polyvinyl chloride fibers;

optionally, the skin-core structure composite fiber used as the skin layer material comprises a polyolefin skin-core structure composite fiber, a copolyester skin-core structure composite fiber and a copolyamide skin-core structure composite fiber.

10. An electromagnetic shielding film comprising the nonwoven fabric according to any one of claims 1 to 9.

Technical Field

The application relates to the field of non-woven fabric materials, in particular to non-woven fabric and an electromagnetic shielding film.

Background

With the popularization of 5G communication technology and the use of a large number of high-power electronic devices, the electromagnetic wave radiation and electromagnetic interference generated thereby are becoming more serious. Various electronic devices generate electromagnetic wave radiation to different degrees, and the electromagnetic wave radiation not only causes mutual interference among electronic products, but also pollutes the living space of human beings and harms the health of the human beings. Many electromagnetic radiation protection standards specify that products that do not meet the standards are not allowed to be released to the market. Reliability has become an important issue for electronic devices, and reliability has also become an important market feature for electronic devices. When the electronic equipment works, the electronic equipment is not expected to be interfered by external electromagnetic waves, and the electronic equipment is not expected to radiate the electromagnetic waves to interfere the external equipment and cause radiation damage to human bodies.

Electromagnetic interference, abbreviated as EMI, is defined as that an interference source emits interference electromagnetic energy, which is transmitted to a sensitive device through a coupling path, so that the operation of the sensitive device is affected. There are two basic conditions for EMI: (1) electromagnetic interference source and sensitive device to the energy of the specific amplitude, frequency that the interference source produces, is called the sensor; (2) a propagation path for energy transmitted between the interference source and the sensor.

Among the many means to solve the problem of electromagnetic interference, the most basic method is electromagnetic shielding. Electromagnetic shielding is to prevent electromagnetic wave radiation from causing interference and leakage by blocking or attenuating electromagnetic energy propagation between the shielded area and the outside with a shielding material. The electromagnetic shielding film is a shielding body made of special materials, and can effectively block electromagnetic interference based on the working principle of reflection of electromagnetic waves or absorption of the electromagnetic waves.

Generally, high electrical conductivity gives excellent electromagnetic shielding property to the material, and the metal material has excellent electrical conductivity and electromagnetic shielding property, so that the metal material is still the main material for the electromagnetic shielding fabric at present. With the development of electronic devices toward "light, thin, short, and small", the requirement for lightness and thinness of electromagnetic shielding film materials is higher and higher while high electromagnetic shielding effectiveness is pursued. However, the current thin electromagnetic shielding film cannot be continuously and uniformly processed, so the electromagnetic shielding effect of the thicker conductive shielding film is better than that of the thinner electromagnetic shielding film. There is a dilemma between the electromagnetic shielding effect of the electromagnetic shielding film and the requirement for the thickness of the electromagnetic shielding film.

Disclosure of Invention

An object of the embodiments of the present application is to provide a nonwoven fabric and an electromagnetic shielding film.

In a first aspect, the present application provides a nonwoven fabric comprising: organic trunk fibers, inorganic trunk fibers, and binder fibers; the mass percentage of the organic main fiber is 20-75%, the mass percentage of the inorganic main fiber is not higher than 35%, and the mass percentage of the bonding fiber is 25-45%; the fiber diameter of the organic trunk fiber is not more than 4 μm; the fiber diameter of the inorganic main fiber is not more than 6 μm; the fiber diameter of the binder fiber is not more than 10 μm.

The non-woven fabric is prepared by doping inorganic trunk fibers in the organic trunk fibers, so that the organic trunk fibers wrap the inorganic fibers, and the bonding fibers provide bonding strength, thereby forming an integral structure. The inorganic main fiber is used as a reinforcing material to strengthen the structural strength of the non-woven fabric, and plays a role similar to that of a steel bar in reinforced concrete. By limiting the mass percentages of the organic trunk fibers, the inorganic trunk fibers and the bonding fibers in the non-woven fabric within the above ranges, the full adhesion and fixation among the fibers in the non-woven fabric are ensured, a compact net structure is formed, the fixation and shaping effects are good, and the mechanical strength of the non-woven fabric is improved. By setting the fiber diameters of the organic main fiber, the inorganic main fiber and the bonding fiber within the above ranges, the thickness of the non-woven fabric can be ensured to be thin, so that the original characteristics of the non-woven fabric can be ensured, the mechanical strength of the non-woven fabric can be obviously improved, the number of fiber layers of the non-woven fabric can be reduced while the same performance is maintained, and the non-woven fabric with thin thickness and high mechanical strength can be obtained.

In other embodiments of the present application, the bonding fibers have a melting point or softening point of 100 ℃ to 250 ℃; the melting point or softening point of the organic main fiber is higher than that of the binder fiber by not less than 20 ℃.

In other embodiments of the present application, the organic backbone fibers, the inorganic backbone fibers, and the binder fibers all have a fiber length in a range of 1mm to 6 mm.

In other embodiments of the present application, the nonwoven fabric has a machine direction tensile strength in the range of 2.5N/15mm to 66N/15 mm; the nonwoven fabric has a transverse tensile strength in the range of 2.0N/15mm to 45N/15 mm.

In other embodiments of the present application, the nonwoven fabric has a density of 0.10g/m³～0.50g/m³Within the range; the thickness of the non-woven fabric is within the range of 5-30 μm.

In other embodiments of the present application, the nonwoven fabric has an average pore size of not more than 5.0mm, and a ratio of a maximum pore size to the average pore size of not less than 1 and not more than 10.

In other embodiments of the present application, the inorganic backbone fiber includes: alumina silicate fibers, mullite fibers, forsterite fibers, alumina fibers, quartz fibers, zirconia fibers, SiO₂CaO-MgO based fiber and Al₂O₃CaO-based fiber, Al₂O₃-SiO₂-ZrO₂Staple fiber, boride fiber, and carbide fiberAt least one of a fiber, a nitride fiber, or a glass fiber;

optionally, the boride fibers comprise zirconium boride fibers;

optionally, the carbide fibers comprise silicon carbide fibers;

optionally, the nitride fibers comprise silicon nitride fibers or boron nitride fibers;

optionally, the glass fibers comprise magnesium aluminum silicon ternary glass fibers, magnesium aluminum silicon series glass fibers, or silicon aluminum calcium magnesium series glass fibers.

In other embodiments of the present application, the organic trunk fiber includes: at least one of polyolefin fiber, polyamide fiber, polyimide fiber, polytetrafluoroethylene fiber, polyvinyl alcohol fiber, polyvinylidene fluoride fiber, polyphenylene sulfide fiber, polyether ether ketone fiber, polyacrylonitrile fiber, polycarbonate fiber, or aramid fiber;

alternatively, the polyamide fiber includes polyester fiber such as polyethylene terephthalate fiber and polybutylene terephthalate fiber, polyethylene fiber, polypropylene fiber, polyvinyl chloride fiber, and ES fiber.

In other embodiments of the present application, the above-mentioned binder fiber comprises: at least one of polyethylene terephthalate undrawn fiber, polybutylene terephthalate undrawn fiber, polyolefin fiber, or sheath-core structure composite fiber as a sheath material;

optionally, the polyolefin fibers include polyethylene fibers, polypropylene fibers, polyvinyl chloride fibers;

optionally, the sheath-core structure composite fiber used as the sheath material comprises a polyolefin sheath-core structure composite fiber, a copolyester sheath-core structure composite fiber, and a copolyamide sheath-core structure composite fiber.

In a second aspect, the present application provides an electromagnetic shielding film comprising the nonwoven fabric of any one of the preceding claims.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions of the embodiments of the present application will be clearly and completely described below, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments.

Thus, the detailed description of the embodiments of the present application provided below is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the present application. 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 application.

Embodiments of the present application provide a nonwoven fabric, comprising: organic trunk fibers, inorganic trunk fibers, and binder fibers; the mass percentage of the organic main fiber is 20-75%, the mass percentage of the inorganic main fiber is not higher than 35%, and the mass percentage of the bonding fiber is 25-45%.

The non-woven fabric disclosed by the application tightly combines the organic main fiber and the inorganic main fiber, fully exerts the advantages of high mechanical strength, good chemical stability and good flexibility and processability of the inorganic main fiber, and makes up for the application defect of a single material.

Furthermore, the mass percentages of the organic trunk fibers, the inorganic trunk fibers and the bonding fibers in the non-woven fabric are limited within the ranges, so that the organic trunk fibers and the inorganic trunk fibers in the non-woven fabric are enabled to generate good synergistic effect, and then the organic trunk fibers and the inorganic trunk fibers are fully adhered and fixed through the bonding fibers to form a compact net-shaped structure, so that the fixing and shaping effects are good, and the mechanical strength of the non-woven fabric is ensured.

The organic trunk fiber and the inorganic trunk fiber act synergistically to generate bonding strength, and can bear acting force generated on an interface by relative deformation of the organic trunk fiber and the inorganic trunk fiber, and the acting force is called bonding stress. The bonding stress enables the inorganic main fiber and the organic main fiber to be reliably anchored, thereby ensuring that the inorganic main fiber and the organic main fiber are jointly deformed under the action of external force or heat. The adhesion between the inorganic and organic backbone fibers is mainly composed of three parts:

(1) the contact surface of the inorganic main fiber and the organic main fiber generates adhesive force due to chemical action.

(2) The organic trunk fiber shrinks when cooled and solidified after being melted, so that the inorganic trunk fiber is wrapped. Due to the gripping action and the rough and uneven surface of the inorganic trunk fiber, the relative sliding tendency between the inorganic trunk fiber and the organic trunk fiber causes frictional resistance on the contact surface. The bonding of inorganic and organic backbone fibers relies primarily on frictional resistance.

(3) The gripping force is a mechanical gripping force generated by the fusion of the organic trunk fiber and the unsmooth surface of the inorganic trunk fiber.

The reinforcing action mechanism of the inorganic trunk fibers is that the inorganic trunk fibers serve as a framework to help the organic trunk fiber matrix to bear load. After the inorganic trunk fibers and the organic trunk fibers are blended, the inorganic trunk fibers are uniformly distributed in the organic trunk fiber matrix, the modulus of the inorganic trunk fibers is greater than that of the organic trunk fiber matrix, and the inorganic trunk fibers bear larger load under the same strain; when the diaphragm receives external force, the action direction of the force is changed from the organic main fiber matrix to the inorganic main fiber, namely, the action is transmitted along the fiber orientation direction, and the transmission action also plays a role in dispersing the force to a certain extent, so that the capability of the film material for bearing the action of the external force is enhanced, and the macroscopically shown that the tolerance of the non-woven fabric in the process of the composite metal layer is greatly improved.

If the mass fraction of the inorganic main fiber is more than 35 wt%, the brittleness of the nonwoven fabric is increased, and the nonwoven fabric is easily torn or damaged in the process of processing and winding. The bonding fiber ensures the bonding force among the fibers, and if the content of the bonding fiber is too low and the content of the organic main fiber is too high, the fibers in the non-woven fabric cannot be fully adhered and fixed, the net structure is loose, and the non-woven fabric is difficult to be fixed and shaped, so the mechanical strength of the non-woven fabric is difficult to ensure. On the contrary, if the content of the binder fiber is too high and the content of the organic main fiber is too low, the excessive binder fiber melts on the surface of the nonwoven fabric, which easily causes severe pore blocking, and makes it difficult to obtain the desired pore structure.

Further, within the mass percent ratio range, the longitudinal tensile strength of the non-woven fabric is within the range of 2.5N/15 mm-66N/15 mm; the transverse tensile strength is within the range of 2.0N/15 mm-45N/15 mm.

Further, within the mass percent ratio range, the longitudinal tensile strength of the non-woven fabric is within the range of 4.5N/15 mm-60N/15 mm; the transverse tensile strength is within the range of 3.5N/15 mm-40N/15 mm.

Illustratively, the nonwoven fabric has a machine direction tensile strength of 4.8N/15mm, 5.3N/15mm, 6.7N/15mm, 7.5N/15mm, 8.6N/15mm, 9.4N/15mm, 10.9N/15mm, 12.4N/15mm, 13.7N/15mm, 15.8N/15mm, 16.4N/15mm, 18.3N/15mm, 20.3N/15mm, 25.8N/15mm, 27.9N/15mm, 29.6N/15mm, 33.5N/15mm, 36.7N/15mm, 38.8N/15mm, 40.7N/15mm, 43.8N/15mm, 47.6N/15mm, 49.5N/15mm, 52.4N/15mm, 56.8N/15mm, or 1.1N/15mm within the above-mentioned mass percent ratio range.

The transverse direction tensile strength is 3.2N/15mm, 4.8N/15mm, 6.2N/15mm, 7.5N/15mm, 8.4N/15mm, 9.7N/15mm, 10.4N/15mm, 12.7N/15mm, 13.9N/15mm, 15.9N/15mm, 16.7N/15mm, 19.2N/15mm, 23.8N/15mm, 26.5N/15mm, 28.9N/15mm, 31.1N/15mm, 34.6N/15mm, 37.9N/15mm, 40.1N/15mm, 42.3N/15mm or 44.6N/15 mm.

Further, the fiber diameter of the organic trunk fiber is not more than 4 μm; the fiber diameter of the inorganic main fiber is not more than 6 μm; the fiber diameter of the binder fiber is not more than 10 μm.

Further optionally, the fiber diameter of the organic trunk fiber is between 0.1 μm and 4 μm; the fiber diameter of the inorganic main fiber is 0.1-6 μm; the diameter of the bonding fiber is 0.1-10 μm. Illustratively, the organic trunk fiber has a fiber diameter of 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, or 3.5 μm. The inorganic main fiber has a fiber diameter of 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm or 5.5 μm. The binder fiber has a fiber diameter of 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm or 9 μm.

By setting the fiber diameters of the organic main fiber, the inorganic main fiber, and the binder fiber within the above ranges, the thickness of the nonwoven fabric can be ensured to be thin.

If the diameter of the organic trunk fiber is larger than 4 μm, the fiber diameter of the inorganic trunk fiber is larger than 6 μm, and the diameter of the bonding fiber is larger than 10 μm, the thickness of the obtained non-woven fabric is too large, and after the non-woven fabric is compounded with the metal layer, the electromagnetic shielding film becomes thick and heavy, and the thickness size is large, so that the electromagnetic shielding requirement in the limited space of the miniaturized electronic equipment cannot be met. Meanwhile, the too thick fibers also increase the possibility of generating large holes on the non-woven fabric, do not help to obtain the expected pore diameter and distribution, and increase the possibility of generating defects such as pinholes on the metal conductive layer.

Further, the thickness of the nonwoven fabric can be reduced to 30 μm or less within the above fiber diameter range.

Further optionally, the nonwoven fabric has a thickness in the range of 5 μm to 30 μm within the fiber diameter range described above. Illustratively, the nonwoven fabric has a thickness of 8 μm, 10 μm, 15 μm, 20 μm, 25 μm, or 30 μm.

The thickness of the non-woven fabric directly affects the thickness of the electromagnetic shielding film after metal plating. If the thickness of the non-woven fabric is larger than 30 μm, the thickness of the shielding film is too large to meet the requirement of narrow installation space of the precision component. If the thickness of the non-woven fabric is less than 5 μm, the shielding film is too thin, the thermal stability and mechanical strength of the shielding film are greatly reduced, the mechanical requirements of the manufacturing and processing process are difficult to meet, and large holes are easily formed in the metal plating process, so that the shielding effect is greatly reduced.

Further, the melting point or softening point of the binding fiber is 100 to 250 ℃; the melting point or softening point of the organic main fiber is higher than that of the binder fiber by not less than 20 ℃.

Setting the melting point or softening point of the bonding fiber to be 100-250 ℃; the melting point or softening point of the organic main fiber is not less than 20 ℃ higher than that of the bonding fiber, so that the bonding strength of the non-woven fabric can be ensured.

The fusion point or softening point of the bonding fiber is relatively low, the bonding fiber is partially or completely melted when the thermal calendering treatment is carried out, all fibers in the non-woven fabric are adhered to each other, and a firm three-dimensional net structure of the non-woven fabric is formed after cooling and solidification. If the melting point or softening point of the bonding fiber is too low, the bonding fiber is easy to be excessively melted in the hot pressing process, and the bonding roller is serious; if the melting point or softening point of the binder fiber is too high, it is not melted in time at the time of hot pressing, making it difficult to obtain sufficient adhesive strength of the nonwoven fabric.

Further, the fiber lengths of the organic trunk fiber, the inorganic trunk fiber and the binder fiber are all in the range of 1mm to 6 mm. Further optionally, the organic backbone fibers, the inorganic backbone fibers, and the binder fibers all have a fiber length in a range of 1.1mm to 5.9 mm.

Illustratively, the organic backbone fibers, inorganic backbone fibers, and binder fibers have a fiber length of 1mm, 1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 4.5mm, or 5 mm.

The lengths of the organic trunk fiber, the inorganic trunk fiber, and the binder fiber may be selected to be the same or different. For example, the organic trunk fibers and the inorganic trunk fibers may be provided with the same length, and the binder fibers may be larger or smaller than the organic trunk fibers or the inorganic trunk fibers. Or the lengths of the organic trunk fiber, the inorganic trunk fiber and the bonding fiber are selected to be the same; or the lengths of the organic trunk fiber, the inorganic trunk fiber and the bonding fiber are different.

The fiber lengths of the organic trunk fiber, the inorganic trunk fiber and the bonding fiber are all within the range of 1-6 mm, so that the strength of the non-woven fabric can be further ensured, and the good forming effect of the non-woven fabric is ensured.

If the length of the fiber is less than 1mm, the problem that the strength of the non-woven fabric is too low may exist, and even the fiber cannot be made into paper; if the length of the fiber is more than 6mm, the overlong fiber is easy to be agglomerated and tangled, and the serious appearance performance defect of the non-woven fabric is caused.

Further, in some embodiments of the present application, the organic trunk fiber described above comprises: at least one of polyolefin fiber, polyamide fiber, polyimide fiber, polytetrafluoroethylene fiber, polyvinyl alcohol fiber, polyvinylidene fluoride fiber, polyphenylene sulfide fiber, polyether ether ketone fiber, polyacrylonitrile fiber, polycarbonate fiber, or aramid fiber.

Further optionally, the polyamide fiber includes polyethylene terephthalate fiber and polybutylene terephthalate fiber.

Further optionally, the polyolefin fibers include polyethylene fibers, polypropylene fibers, polyvinyl chloride fibers, and ES fibers.

Further, in some embodiments of the present application, the inorganic backbone fiber includes: alumina silicate fibers, mullite fibers, forsterite fibers, alumina fibers, quartz fibers, zirconia fibers, SiO₂CaO-MgO based fiber and Al₂O₃CaO-based fiber, Al₂O₃-SiO₂-ZrO₂At least one of a fiber, a boride fiber, a carbide fiber, a nitride fiber, or a glass fiber.

Further optionally, the boride fibers described above include zirconium boride fibers.

Further optionally, the carbide fibers comprise silicon carbide fibers.

Further optionally, the nitride fiber includes a silicon nitride fiber and a boron nitride fiber.

Further optionally, the glass fibers include magnesium aluminum silicon ternary glass fibers, magnesium aluminum silicon glass fibers, and silicon aluminum calcium magnesium glass fibers.

Further, in some embodiments of the present application, the above-mentioned binder fiber comprises: polyethylene terephthalate undrawn fiber, polybutylene terephthalate undrawn fiber, polyolefin fiber, or sheath-core structure composite fiber as a sheath material.

Further optionally, the polyolefin fibers include polyethylene fibers, polypropylene fibers, and polyvinyl chloride fibers.

Further optionally, the sheath-core structure composite fiber used as the sheath material includes a polyolefin sheath-core structure composite fiber, a copolyester sheath-core structure composite fiber, and a copolyamide sheath-core structure composite fiber.

In some embodiments of the present application, the nonwoven fabric has a density of 0.10g/m³～0.50g/m³Within the range.

By setting the density of the nonwoven fabric within the above range, a good heat dissipation effect can be ensured.

The non-woven fabric has a density of 0.10 to 0.50g/m³If the density is less than 0.10g/m³The mechanical performance and the shielding performance of the electromagnetic shielding film are greatly weakened due to the fact that the strength of the non-woven fabric is too low and the number of large through holes is too large. If the density is more than 0.50g/m³The dense and compact organic polymer fiber layer automatically forms an 'insulating layer', so that heat generated by electronic devices such as chips and the like is prevented from being transferred in time, poor heat dissipation is caused, the working temperature of the precision devices is easy to exceed a normal allowable range by the accumulated heat, and the device equipment is damaged in serious cases.

In some embodiments of the present application, the nonwoven fabric has an average pore size of not greater than 5.0mm, and a ratio of a maximum pore size to the average pore size of not less than 1 and not greater than 10.

The average pore diameter of the non-woven fabric is not more than 5.0mm, the ratio of the maximum pore diameter to the average pore diameter is not less than 1 and not more than 10, the distance between fibers is not too large to separate, when chemical plating is carried out, metal easily enters the hole and forms a continuous layer with surface metal, and high-performance electromagnetic shielding performance can be realized. When the average pore diameter is larger than 5.0mm and the maximum pore diameter/average pore diameter ratio is larger than 10, through holes are easy to be formed in the metal conducting layer, at the moment, in order to completely cover the surface of the non-woven fabric to ensure the electromagnetic shielding efficiency, the metal coating needs to be thickened, and the internal stress accumulation of metal particles is too large due to the excessively thick coating, so that the adhesion fastness of the coating is poor and the coating is easy to fall off.

The nonwoven fabric of the present application is not particularly limited in preparation method, and a nonwoven fabric preparation method known in the art can be used. For example, an inclined wire paper machine is adopted to make fiber base paper, then hot calendering treatment is carried out on the formed fiber base paper, a hot press adopts a combination of a steel roller and a soft roller, the treatment temperature range is 100-300 ℃, and the non-woven fabric can be obtained.

Some embodiments of the present application provide an electromagnetic shielding film including the nonwoven fabric provided in any of the preceding embodiments. The non-woven fabric serves as a support layer of the electro-magnetic shielding film. Further, a metal layer is compounded on the surface of the non-woven fabric.

Due to the fact that the non-woven fabric is arranged, the mechanical strength of the electromagnetic shielding film can be greatly improved, and meanwhile the thickness of the electromagnetic shielding film is small, so that the application scene of the electromagnetic shielding film is widened.

Furthermore, the heat conductivity coefficient of the inorganic fiber is obviously higher than that of the organic fiber, and the non-woven fabric obtained by compounding the organic fiber and the inorganic fiber is used as a supporting layer of the electromagnetic shielding film, so that the adverse effect of the organic fiber on the heat conductivity of the film material can be effectively reduced. Therefore, after the metal layer is compounded on the surface of the non-woven fabric, the electromagnetic shielding film can be thinned and has high strength, so that the requirements on high shielding efficiency, high thermal conductivity and thin thickness of the electromagnetic shielding film can be met, and the electromagnetic shielding film is convenient to apply to precise devices and equipment in small space.

The features and properties of the present application are described in further detail below with reference to examples:

example 1

Providing an electromagnetic shielding film, which is prepared according to the following steps:

and step S1, preparing the non-woven fabric.

Providing a non-woven fabric, taking organic main fibers, inorganic main fibers and bonding fibers as raw materials, adopting an inclined wire paper machine to make fiber base paper, and then carrying out hot calendering treatment on the fiber base paper, wherein the treatment temperature is 225 +/-5 ℃; the hot calender adopts a steel roller/soft roller combination. Specific contents, properties and fiber layer density of the organic trunk fiber, inorganic trunk fiber and binder fiber are shown in table 1.

And step S2, preparing the electromagnetic shielding film.

The non-woven fabric obtained in the step S1 is used as a support layer of the electromagnetic shielding film, and the non-woven fabric is plated with metal copper, wherein the metal adhesion amount is 3g/m²And obtaining the electromagnetic shielding film sample 1.

Examples 2 to 4

An electromagnetic shielding film was provided, which was prepared in the same manner as in example 1 except that the fiber material was different, as shown in table 1.

Comparative examples 1 to 4

An electromagnetic shielding film was provided, which was prepared in the same manner as in example 1 except that the fiber material was different, as shown in table 1.

TABLE 1

Examples of the experiments

(1) The properties of the nonwoven fabrics obtained in step S1 of examples 1 to 4 were examined.

Wherein the "areal density" of the nonwoven fabric is determined according to the method of GB/T451.2-2002. The "density" of the nonwoven fabric is determined by dividing the "areal density" of the nonwoven fabric by the "thickness" of the nonwoven fabric, which is determined according to GB/T451.3-2002. The "pore size" of the nonwoven fabric was determined according to GB/T32361-2015 method. The "tensile strength" of the nonwoven was determined according to GB/T12914-.

(2) The electromagnetic shielding films manufactured in step S2 of examples 1 to 4 were tested for their properties.

Wherein, the 'electromagnetic shielding effectiveness' of the electromagnetic shielding film is tested according to the GB/T30142 and 2013 method.

The evaluation standard of the metal coating compactness of the electromagnetic shielding film is as follows:

o: the plating layer is compact, has no holes and has excellent level;

and (delta): 1-5 parts/m of coating²Hole, medium level;

x: appearance of plating>At 5/m²Holes, unusable levels.

The test results are shown in table 2.

TABLE 2

It can be seen from table 2 that the samples of examples 1 to 4 of the present application have good properties, in particular a significant improvement in tensile strength. The longitudinal tensile strength of the non-woven fabric is in the range of 36.5N/15 mm-65.2N/15 mm; the transverse tensile strength is in the range of 29.8N/15 mm-44.1N/15 mm, so that the longitudinal tensile strength of the electromagnetic shielding film is in the range of 41.6N/15 mm-69.9N/15 mm, and the transverse tensile strength is in the range of 33.9N/15 mm-47.2N/15 mm. And the thickness of the electromagnetic shielding film is thin and can reach 12.1 mu m, and the electromagnetic shielding efficiency of the electromagnetic shielding film is high and can reach 73dB (at 1 GHz).

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.