CN114058296B

CN114058296B - Electromagnetic shielding function composite pressure-sensitive adhesive with oriented structure and preparation method thereof

Info

Publication number: CN114058296B
Application number: CN202111568342.XA
Authority: CN
Inventors: 张扬; 王晨卉; 高晗; 刘帅
Original assignee: Beijing Technology and Business University
Current assignee: Beijing Technology and Business University
Priority date: 2021-12-21
Filing date: 2021-12-21
Publication date: 2022-12-06
Anticipated expiration: 2041-12-21
Also published as: CN114058296A

Abstract

The invention discloses an electromagnetic shielding function composite pressure-sensitive adhesive with an oriented structure and a preparation method thereof, belonging to the field of preparation of electromagnetic shielding materials. The composite pressure-sensitive adhesive is prepared by a method of externally adding a static magnetic field and performing solution casting. The composite pressure-sensitive adhesive has a three-layer structure, and the metal magnetic filler has different orientation structures in the thickness direction of each layer. The filler on the upper layer perpendicular to the direction of the base film is beneficial to the entering of electromagnetic waves; the filler with the middle layer forming a certain inclination angle with the horizontal plane is beneficial to generating a large amount of multiple reflection and scattering of electromagnetic waves; the lower layer of filler parallel to the base film direction can re-reflect the electromagnetic waves to the interior of the material. The good matching of the three layers greatly attenuates electromagnetic radiation, so that the pressure-sensitive adhesive prepared by the invention has the characteristics of high shielding efficiency and strong absorption. In addition, the composite pressure-sensitive adhesive provided by the invention can be repeatedly pasted for use, and can be widely applied to the fields of flexible electronic equipment, portable and wearable electronic products and the like.

Description

Electromagnetic shielding function composite pressure-sensitive adhesive with oriented structure and preparation method thereof

Technical Field

The invention relates to the technical field of electromagnetic shielding composite materials, in particular to an electromagnetic shielding function composite pressure-sensitive adhesive with an oriented structure and a method for preparing the electromagnetic shielding function composite pressure-sensitive adhesive with the oriented structure by an external static magnetic field.

Background

With the increase of the usage amount of electronic and electrical equipment, a complex electromagnetic environment is formed. Electromagnetic interference can not only cause malfunction of electrical equipment, but can also cause information leakage, erroneous operation, and damage to the performance of electronic equipment. The research on the electromagnetic interference shielding technology is increasingly gaining attention.

The polymer-based pressure-sensitive adhesive can firmly bond the two materials together, and has convenient use and low price. However, due to the insulating properties, such pressure sensitive adhesives do not have electromagnetic shielding capabilities, limiting their application as electromagnetic shielding materials. The functional filler is filled in the polymer to endow the polymer with electromagnetic shielding effectiveness. High filling content, although improving the electromagnetic shielding performance of the material, can cause a series of adverse effects such as weak interface adhesion, high cost, poor processing capability, and the like. With the development of the new generation of flexible electronic devices towards intellectualization, portability and wearability, higher requirements are also provided for the flexibility, light weight and other aspects of the electromagnetic shielding material, and research and preparation of novel high-performance and multifunctional flexible electromagnetic shielding pressure-sensitive adhesive are urgently needed.

CN 110408342A discloses a preparation method of a carbon nanosphere filled dual-curing conductive adhesive tape and application of the carbon nanosphere filled dual-curing conductive adhesive tape in an electromagnetic shielding adhesive tape. Firstly, adding carbon nanospheres into N-vinyl pyrrolidone, uniformly stirring, adding an initiator, and continuously stirring to obtain a carbon nanosphere initiator solution; secondly, adding isobornyl acrylate, acrylic acid and isooctyl acrylate into N-vinyl pyrrolidone, uniformly stirring, adding a photoinitiator in a dark environment, and continuously stirring to obtain an acrylate precursor polymer; then, under a dark environment, mixing the carbon nanosphere initiator solution and the acrylate precursor polymer, heating and stirring for pre-reaction, and then adding the initiator for continuous reaction to obtain the carbon nanosphere modified polyacrylate pressure-sensitive adhesive; and finally, fully soaking the polyethylene glycol terephthalate film in the carbon nanosphere modified polyacrylate pressure-sensitive adhesive, pulling and taking out, and irradiating and curing by ultraviolet light to obtain the carbon nanosphere filled dual-cured double-sided conductive adhesive tape. The preparation method has the advantages of complex process and higher requirements on process conditions, and the maximum electromagnetic shielding efficiency of the prepared material is 28dB.

CN 103525340A discloses a water-soluble epoxy modified acrylate resin adhesive and an electromagnetic shielding adhesive film prepared by using the same. The polymerization is carried out by using three or more of butyl acrylate, methyl methacrylate, acrylic acid, methacrylic acid and styrene in a mixture and initiating by a water-soluble initiator. In addition, the components such as emulsifier, epoxy resin, curing agent, thickening agent, electromagnetic shielding particles and the like are required to be added to prepare the electromagnetic shielding adhesive film. The preparation method requires more experimental raw materials and has complex process. The filler is distributed in the prepared adhesive film in a disordered way, so that the advantage that the unique structure of the filler is not favorable for exerting the electromagnetic property of the material is improved.

Disclosure of Invention

The invention aims to provide an electromagnetic shielding function composite pressure-sensitive adhesive with an oriented structure.

The electromagnetic shielding function composite pressure-sensitive adhesive with the orientation structure is characterized by having a three-layer structure, wherein the metal magnetic filler has different orientation structures in the thickness direction of each layer.

Further, the metal functional filler is oriented parallel to the base film direction inside the lower layer and oriented at an angle α to the horizontal plane inside the intermediate layer, wherein 0 ° < α <90 °, or 90 ° < α <180 °, is oriented perpendicular to the base film direction inside the upper layer. Preferably, α may be 10 °, 20 °, 30 °, 40 °, 50 °, 60 °, 70 °, 80 °, 120 °, 150 °. Most preferably 50 ° < α <60 ° or 120 ° < α <130 °

Furthermore, the composite pressure-sensitive adhesive with the electromagnetic shielding function mainly comprises two parts, namely acrylate pressure-sensitive adhesive and metal magnetic filler.

Further, the initial viscosity of the acrylate pressure-sensitive adhesive is 3000-5000 CPS, and the peel strength is 1.20-1.50N/mm.

Further, the metal magnetic filler is formed by compounding chain spherical nickel powder and flaky nickel powder; wherein the average chain length of the chain-shaped nickel powder is 16.0-70.0 μm, and the average flake diameter of the flake nickel powder is 22.0-68.0 μm.

Further, the solid content of the acrylate pressure-sensitive adhesive is 30.0-60.0 wt.%, and the mass ratio of the metal magnetic filler on the upper layer, the middle layer and the lower layer to the solid content of each layer of the electromagnetic shielding function composite pressure-sensitive adhesive is 1-2: 1-2, wherein the mass ratio of the middle layer chain spherical metal magnetic filler to the flaky metal magnetic filler is 1-8: 1.

furthermore, the thickness of each layer of the electromagnetic shielding function composite pressure-sensitive adhesive is 0.10-0.20 mm.

The invention also provides a preparation method of the electromagnetic shielding function composite pressure-sensitive adhesive with the orientation structure, wherein the orientation structure is constructed by adopting a method of combining an external static magnetic field and solution casting, and an orientation base film layer L1 (lower layer) with metal function fillers oriented in a direction parallel to the base film, an orientation film layer L2 (middle layer) with the metal function fillers oriented at an alpha angle relative to the base film direction and an orientation film layer L3 (upper layer) with the metal function fillers oriented in a direction vertical to the base film are sequentially formed on the surface of the base film. The preparation method specifically comprises the following steps:

(1) Adding the flaky nickel powder into acrylate pressure-sensitive adhesive (the mass ratio of the flaky nickel powder to the solid content of the acrylate pressure-sensitive adhesive is 1-2:1-2), stirring, and defoaming to prepare mixed liquid S1 and S3;

(2) Adding chain spherical and flaky nickel powder (the weight ratio of the chain spherical powder to the flaky powder is 1-8:1) into acrylate pressure-sensitive adhesive (the weight ratio of the nickel powder to the solid content of the acrylate pressure-sensitive adhesive is 1-2:1-2), stirring, and defoaming to prepare mixed solution S2;

(3) Casting the mixed solution S1 on the surface of a horizontally placed polyethylene base film, placing the polyethylene base film into a static magnetic field, orienting the polyethylene base film in a direction parallel to the direction of the base film for 3-4h, and then placing the polyethylene base film into an oven for drying to obtain an L1 oriented film;

(4) After the mixed solution S1 is completely dried, casting a mixed solution S2 on the air side surface of the L1 orientation film, placing the mixed solution into a static magnetic field, wherein the direction of the magnetic field forms an alpha angle with the horizontal plane, the alpha angle is 0 degrees < alpha <90 degrees or 90 degrees < alpha <180 degrees, the orientation time is 3-4h, and then placing the mixed solution into an oven for drying to obtain an L1+ L2 orientation film;

(5) And after the mixed solution S2 is completely dried, casting the mixed solution S3 on the surface of the air side of the L2 surface of the obtained L1+ L2 oriented film, putting the mixed solution into a static magnetic field, wherein the direction of the magnetic field is vertical to the direction of the base film, the orientation time is 3-4h, putting the mixed solution into an oven for drying, and finally obtaining the L1+ L2+ L3 composite pressure-sensitive adhesive with the oriented structure and the electromagnetic shielding function after the mixed solution is completely dried.

And (3) performance testing:

and (3) testing the electromagnetic shielding effectiveness: electromagnetic shielding effectiveness was tested according to standard GBJ 8820-2015.

And (3) testing the peel strength: the peel strength was tested according to the standard GB/T8808-1988.

The invention has the beneficial effects that:

the composite pressure-sensitive adhesive with the electromagnetic shielding function has a three-layer structure, and the metal magnetic filler has different orientation structures in the thickness direction of each layer. The metal filler is oriented in the direction vertical to the base film in the upper layer (L3) of the composite pressure-sensitive adhesive, oriented in a certain inclination angle with the horizontal plane in the middle layer (L2), and oriented in the direction parallel to the base film in the lower layer (L1). When electromagnetic waves enter the material from the upper layer of the pressure-sensitive adhesive, the metal functional filler vertical to the direction of the base film is beneficial to the entering of the electromagnetic waves, and the problem of electromagnetic secondary pollution caused by strong reflection of the electromagnetic waves on the surface of the pressure-sensitive adhesive is effectively avoided. When electromagnetic waves enter the middle layer, the metal functional filler which forms a certain inclined angle with the horizontal plane is beneficial to the generation of a large amount of multiple reflection and scattering of the electromagnetic waves, so that the electromagnetic waves are greatly attenuated in the middle layer. When the electromagnetic wave got into the lower floor, the metal function that is on a parallel with the base film direction was packed and can be made the electromagnetic wave reflect again and enter into the inside of pressure sensitive adhesive, has prolonged the transmission path of electromagnetic wave in the material is inside, and the effectual rate of utilization that has promoted metal packing makes electromagnetic energy further weaken. The electromagnetic radiation is greatly attenuated due to the good electromagnetic matching characteristic of the three layers, so that the pressure-sensitive adhesive prepared by the invention has the characteristics of high shielding efficiency and strong absorption. Meanwhile, no organic solvent is used in the process of preparing the pressure-sensitive adhesive, and the pressure-sensitive adhesive is low in price, green, energy-saving and environment-friendly. The electromagnetic shielding function composite pressure-sensitive adhesive has good flexibility and strong adhesion performance, can be conveniently adhered to the surfaces of products and equipment needing electromagnetic protection, and can be repeatedly adhered for use. In addition, the method has the advantages of simple preparation process, easily controlled flow, easy large-scale industrial production and the like.

Drawings

FIG. 1 is a schematic structural diagram of an electromagnetic shielding composite pressure-sensitive adhesive with an oriented structure prepared by the present invention;

fig. 2 is a graph showing the electromagnetic shielding effectiveness of the electromagnetic shielding function composite pressure-sensitive adhesive with an oriented structure prepared in example 26 at 8.2-12.4 GHz.

Detailed Description

The electromagnetic shielding function composite pressure-sensitive adhesive having an oriented structure and the method for preparing the same according to the present invention will be described in more detail by way of exemplary embodiments. These embodiments are provided so that this disclosure will be thorough and complete and will fully convey the invention to those skilled in the art, and the present invention will not be limited to the exemplary embodiments set forth.

The test method comprises the following steps:

electromagnetic shielding effectiveness of the composite pressure-sensitive adhesive: the waveguide method was used for testing.

Absorption loss in percentage of electromagnetic shielding effectiveness: SE _A ％＝SE _A (SE), wherein SE represents the total electromagnetic shielding effectiveness in dB; SE _A Shielding effectiveness, in dB, representing absorption loss; SE _A % represents the shielding effectiveness of absorption loss as a percentage of the total shielding effectiveness.

Example 1:

(1) Two parts of 45.0g of flaky nickel powder with the average flake diameter of 22.0 mu m and 100.0g of acrylate pressure-sensitive adhesive with the solid content of 45.0wt.% are weighed respectively and placed into a single-neck flask. At room temperature, the two parts of mixed solution S1 and S3 are obtained after the mixed solution is stirred for 1h at the rotating speed of 150rpm and is uniformly mixed by mechanical stirring; a portion of 22.5g of hammer nickel powder with an average chain length of 16.0 mu m, 22.5g of flaky nickel powder with an average flake diameter of 22.0 mu m and 100.0g of acrylate pressure-sensitive adhesive with a solid content of 45.0wt.% are weighed and placed into a single-neck flask. The mixture was stirred at room temperature by mechanical stirring at 150rpm for 1 hour to give a mixed solution S2.

(2) And (3) placing the mixed solution S1, S2 and S3 into a vacuum defoaming machine for defoaming for 30min.

(3) And placing the mixed solution S1 into a casting box of a casting machine, casting the surface of a horizontally placed polyethylene base film, placing the polyethylene base film in a 1.2T static magnetic field parallel to the base film for 4h, and then placing the polyethylene base film in a 60 ℃ drying oven for drying to obtain the L1 oriented film.

(4) After the mixed solution S1 is completely dried, casting the mixed solution S2 on the air side surface of the L1 orientation film, placing the mixed solution S2 into a casting box of a casting machine, casting on the air side surface of the L1 orientation film, then placing the L1 orientation film into a 1.2T static magnetic field which forms 10 degrees with the horizontal plane for 4h, and placing the L1+ L2 orientation film into an oven at 60 ℃ for drying to obtain the L1+ L2 orientation film.

(5) After the mixed solution S2 is completely dried, casting the mixed solution S3 on the air side surface of the L2 surface of the L1+ L2 oriented film, putting the mixed solution S3 into a casting machine casting box, casting on the air side surface of the L2 surface of the L1+ L2 oriented film, then putting the mixed solution into a 1.2T static magnetic field vertical to the base film direction for 4h, putting the mixed solution into an oven at 60 ℃ for drying, and after the mixed solution is completely dried, obtaining the L1+ L2+ L3 composite pressure-sensitive adhesive with the electromagnetic shielding function and the oriented structure.

The thickness of each of the L1, L2, and L3 oriented films was 0.10mm by controlling the height of the doctor blade during casting. The electromagnetic shielding performance of the composite pressure-sensitive adhesive is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding efficiency of the composite pressure-sensitive adhesive can reach 15.22dB, the absorption loss accounts for 36.23% of the total shielding efficiency, and the peel strength is 0.55N/mm. The properties of the materials are listed in table 1.

Example 2:

the procedure is as in example 1 except that the average chain length of the nickel powder in the form of spheres in the chain of (1) is adjusted from 16.0. Mu.m to 57.0. Mu.m. The electromagnetic shielding performance of the composite pressure-sensitive adhesive is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding performance of the composite pressure-sensitive adhesive can reach 33.45dB, the absorption loss accounts for 42.15% of the total shielding performance, and the peel strength is 0.63N/mm. The properties of the materials are listed in table 1.

Example 3:

the procedure is as in example 1 except that the average chain length of the nickel powder in the form of spheres in the chain of (1) is adjusted from 16.0. Mu.m to 70.0. Mu.m. The electromagnetic shielding performance of the composite pressure-sensitive adhesive is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding performance of the composite pressure-sensitive adhesive can reach 28.74dB, the absorption loss accounts for 40.71% of the total shielding performance, and the peel strength is 0.59N/mm. The properties of the materials are listed in table 1.

Example 4:

the procedure is as in example 2, except that the average platelet diameter of the flaky nickel powder in (1) is adjusted from 22.0 μm to 49.0. Mu.m. The electromagnetic shielding performance of the composite pressure-sensitive adhesive is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding performance of the composite pressure-sensitive adhesive can reach 38.23dB, the absorption loss accounts for 45.74% of the total shielding performance, and the peel strength is 0.68N/mm. The properties of the materials are listed in table 1.

Example 5:

the procedure is as in example 2, except that the average platelet diameter of the flaky nickel powder in (1) is adjusted from 22.0 μm to 68.0. Mu.m. The electromagnetic shielding performance of the composite pressure-sensitive adhesive is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding efficiency of the composite pressure-sensitive adhesive can reach 34.12dB, the absorption loss accounts for 43.25% of the total shielding efficiency, and the peel strength is 0.65N/mm. The properties of the materials are listed in table 1.

Example 6:

the method is as in example 4 except that the angle between the static magnetic field and the horizontal plane in (4) is adjusted from 10 to 20. The electromagnetic shielding performance of the composite pressure-sensitive adhesive is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding performance of the composite pressure-sensitive adhesive can reach 41.04dB, the absorption loss accounts for 46.08 percent of the total shielding performance, and the peel strength is 0.70N/mm. The properties of the materials are listed in table 1.

Example 7:

the method is as in example 4 except that the angle between the static magnetic field and the horizontal plane in (4) is adjusted from 10 to 30. The electromagnetic shielding performance of the composite pressure-sensitive adhesive is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding performance of the composite pressure-sensitive adhesive can reach 43.67dB, the absorption loss accounts for 49.40% of the total shielding performance, and the peel strength is 0.71N/mm. The properties of the materials are listed in table 1.

Example 8:

the method is as in example 4 except that the angle between the static magnetic field and the horizontal plane in (4) is adjusted from 10 to 40. The electromagnetic shielding performance of the composite pressure-sensitive adhesive is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding efficiency of the composite pressure-sensitive adhesive can reach 48.36dB, the absorption loss accounts for 52.73 percent of the total shielding efficiency, and the peel strength is 0.73N/mm. The properties of the materials are listed in table 1.

Example 9:

the procedure was as in example 4 except that the angle between the static magnetic field and the horizontal plane in (4) was adjusted from 10 to 50. The electromagnetic shielding performance of the composite pressure-sensitive adhesive is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding performance of the composite pressure-sensitive adhesive can reach 68.61dB, the absorption loss accounts for 76.98% of the total shielding performance, and the peel strength is 0.88N/mm. The properties of the materials are listed in table 1.

Example 10:

the procedure is as in example 4, except that the angle between the static magnetic field and the horizontal plane in (4) is adjusted from 10 ° to 60 °. The electromagnetic shielding performance of the composite pressure-sensitive adhesive is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding performance of the composite pressure-sensitive adhesive can reach 70.52dB, the absorption loss accounts for 78.36% of the total shielding performance, and the peel strength is 0.90N/mm. The properties of the materials are listed in table 1.

Example 11:

the procedure is as in example 4, except that the angle between the static magnetic field and the horizontal plane in (4) is adjusted from 10 ° to 70 °. The electromagnetic shielding performance of the composite pressure-sensitive adhesive is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding performance of the composite pressure-sensitive adhesive can reach 69.87dB, the absorption loss accounts for 77.14% of the total shielding performance, and the peel strength is 0.89N/mm. The properties of the materials are listed in table 1.

Example 12:

the procedure is as in example 4, except that the angle between the static magnetic field and the horizontal plane in (4) is adjusted from 10 ° to 80 °. The electromagnetic shielding performance of the composite pressure-sensitive adhesive is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding performance of the composite pressure-sensitive adhesive can reach 43.99dB, the absorption loss accounts for 55.97% of the total shielding performance, and the peel strength is 0.69N/mm. The properties of the materials are listed in table 1.

Example 13:

the procedure is as in example 4, except that the residence time in (3), (4) and (5) is adjusted from 4h to 3h. (4) The included angle between the middle static magnetic field and the horizontal plane is adjusted to 150 degrees from 10 degrees. The electromagnetic shielding performance of the composite pressure-sensitive adhesive is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding efficiency of the composite pressure-sensitive adhesive can reach 43.67dB, the absorption loss accounts for 49.50% of the total shielding efficiency, and the peel strength is 0.68N/mm. The properties of the materials are listed in table 1.

Example 14:

the procedure of example 10 was followed except that in the case of preparing the mixed solution S2 in (1), the mass of the hammer nickel powder was adjusted from 22.5g to 27.0g, and the mass of the flake nickel powder was adjusted from 22.5g to 18.0g. The electromagnetic shielding performance of the composite pressure-sensitive adhesive is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding efficiency of the composite pressure-sensitive adhesive can reach 80.13dB, the absorption loss accounts for 86.77% of the total shielding efficiency, and the peel strength is 1.10N/mm. The properties of the materials are listed in table 1.

Example 15:

the procedure of example 10 was repeated except that when the mixed solution S2 was prepared in (1), the mass of the hammer nickel powder was adjusted from 22.5g to 32.0g, and the mass of the flake nickel powder was adjusted from 22.5g to 13.0g. The electromagnetic shielding performance of the composite pressure-sensitive adhesive is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding performance of the composite pressure-sensitive adhesive can reach 77.11dB, the absorption loss accounts for 83.15% of the total shielding performance, and the peel strength is 0.94N/mm. The properties of the materials are listed in table 1.

Example 16:

the procedure of example 10 was followed except that in the case of preparing the mixed solution S2 in (1), the mass of the hammer nickel powder was adjusted from 22.5g to 36.0g, and the mass of the flake nickel powder was adjusted from 22.5g to 9.0g. The electromagnetic shielding performance of the composite pressure-sensitive adhesive is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding performance of the composite pressure-sensitive adhesive can reach 75.59dB, the absorption loss accounts for 80.90% of the total shielding performance, and the peel strength is 0.92N/mm. The properties of the materials are listed in table 1.

Example 17:

the procedure of example 10 was repeated except that in the case of preparing the mixed solution S2 in (1), the mass of the hammer nickel powder was adjusted from 22.5g to 40.0g, and the mass of the flake nickel powder was adjusted from 22.5g to 5.0g. The electromagnetic shielding performance of the composite pressure-sensitive adhesive is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding performance of the composite pressure-sensitive adhesive can reach 63.31dB, the absorption loss accounts for 72.67 percent of the total shielding performance, and the peel strength is 0.83N/mm. The properties of the materials are listed in table 1.

Example 18:

the procedure is as in example 14, except that when the mixed liquids S1 and S3 are prepared in (1), the mass of the flaky nickel powder is adjusted from 45.0g to 22.5g; when the mixed solution S2 was prepared, the mass of the hammer nickel powder was adjusted from 27.0g to 13.5g, and the mass of the flake nickel powder was adjusted from 18.0g to 9.0g. The electromagnetic shielding performance of the composite pressure-sensitive adhesive is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding performance of the composite pressure-sensitive adhesive can reach 55.48dB, the absorption loss accounts for 66.40% of the total shielding performance, and the peel strength is 1.09N/mm. The properties of the materials are listed in table 1.

Example 19:

the procedure is as in example 14 except that when the mixed liquids S1 and S3 are prepared in (1), the mass of the flaky nickel powder is adjusted from 45.0g to 90.0g; when the mixed solution S2 was prepared, the mass of the hammer nickel powder was adjusted from 27.0g to 54.0g, and the mass of the flake nickel powder was adjusted from 18.0g to 36.0g. The electromagnetic shielding performance of the composite pressure-sensitive adhesive is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding performance of the composite pressure-sensitive adhesive can reach 81.89dB, the absorption loss accounts for 88.18% of the total shielding performance, and the peel strength is 1.12N/mm. The properties of the materials are listed in table 1.

Example 20:

the method is as in example 14, except that when the mixed solutions S1 and S3 are prepared in (1), the mass of the flaky nickel powder is adjusted from 45.0g to 30.0g, and the solid content of the acrylate pressure-sensitive adhesive is adjusted from 45.0wt.% to 30.0wt.%; when the mixed solution S2 is prepared, the mass of the hammer nickel powder is adjusted from 27.0g to 18.0g, the mass of the flake nickel powder is adjusted from 18.0g to 12.0g, and the solid content of the acrylate pressure-sensitive adhesive is adjusted from 45.0wt.% to 30.0wt.%. The electromagnetic shielding performance of the composite pressure-sensitive adhesive is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding efficiency of the composite pressure-sensitive adhesive can reach 77.76dB, the absorption loss accounts for 84.82 percent of the total shielding efficiency, and the peel strength is 1.01N/mm. The properties of the materials are listed in table 1.

Example 21:

the method is as in example 20, except that when the mixed liquids S1 and S3 are prepared in (1), the mass of the flaky nickel powder is adjusted from 30.0g to 15.0g; when the mixed solution S2 was prepared, the mass of the hammer nickel powder was adjusted from 18.0g to 9.0g, and the mass of the flake nickel powder was adjusted from 12.0g to 6.0g. The electromagnetic shielding performance of the composite pressure-sensitive adhesive is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding performance of the composite pressure-sensitive adhesive can reach 51.31dB, the absorption loss accounts for 62.29 percent of the total shielding performance, and the peel strength is 0.99N/mm. The properties of the materials are listed in table 1.

Example 22:

the method is as in example 20, except that when the mixed liquids S1 and S3 are prepared in (1), the mass of the flaky nickel powder is adjusted from 30.0g to 60.0g; when the mixed solution S2 was prepared, the mass of the hammer nickel powder was adjusted from 18.0g to 36.0g, and the mass of the flake nickel powder was adjusted from 12.0g to 24.0g. The electromagnetic shielding performance of the composite pressure-sensitive adhesive is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding performance of the composite pressure-sensitive adhesive can reach 78.43dB, the absorption loss accounts for 86.36% of the total shielding performance, and the peel strength is 1.02N/mm. The properties of the materials are listed in table 1.

Example 23:

the method is as in example 20, except that when the mixed solutions S1 and S3 are prepared in (1), the mass of the flaky nickel powder is adjusted from 30.0g to 60.0g, and the solid content of the acrylate pressure-sensitive adhesive is adjusted from 30.0wt.% to 60.0wt.%; when the mixed solution S2 is prepared, the mass of the hammer nickel powder is adjusted from 18.0g to 36.0g, the mass of the flake nickel powder is adjusted from 12.0g to 24.0g, and the solid content of the acrylate pressure-sensitive adhesive is adjusted from 30.0wt.% to 60.0wt.%. The electromagnetic shielding performance of the composite pressure-sensitive adhesive is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding performance of the composite pressure-sensitive adhesive can reach 50.49dB, the absorption loss accounts for 58.32 percent of the total shielding performance, and the peel strength is 0.75N/mm. The properties of the materials are listed in table 1.

Example 24:

the procedure is as in example 23, except that when the mixed liquids S1 and S3 are prepared in (1), the mass of the flaky nickel powder is adjusted from 60.0g to 30.0g; when the mixed solution S2 was prepared, the mass of the hammer nickel powder was adjusted from 36.0g to 18.0g, and the mass of the flake nickel powder was adjusted from 24.0g to 12.0g. The electromagnetic shielding performance of the composite pressure-sensitive adhesive is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding efficiency of the composite pressure-sensitive adhesive can reach 42.36dB, the absorption loss accounts for 49.68% of the total shielding efficiency, and the peel strength is 0.74N/mm. The properties of the materials are listed in table 1.

Example 25:

the procedure is as in example 23, except that when the mixed liquids S1 and S3 are prepared in (1), the mass of the flaky nickel powder is adjusted from 60.0g to 120.0g; when the mixed solution S2 was prepared, the mass of the hammer nickel powder was adjusted from 36.0g to 72.0g, and the mass of the flake nickel powder was adjusted from 24.0g to 48.0g. The electromagnetic shielding performance of the composite pressure-sensitive adhesive is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding performance of the composite pressure-sensitive adhesive can reach 55.43dB, the absorption loss accounts for 64.75% of the total shielding performance, and the peel strength is 0.76N/mm. The properties of the materials are listed in table 1.

Example 26:

the method was as in example 14, by controlling the blade height during casting so that the thickness of each of the L1, L2, L3 oriented films was 0.15mm. The electromagnetic shielding performance of the composite pressure-sensitive adhesive is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding performance of the composite pressure-sensitive adhesive can reach 92.95dB, the absorption loss accounts for 89.18 percent of the total shielding performance, and the peel strength is 1.21N/mm. The electromagnetic shielding effectiveness of the composite pressure sensitive adhesive as a function of frequency is shown in fig. 2. The properties of the materials are listed in table 1.

Example 27:

the method was as in example 14, by controlling the blade height during casting so that the thicknesses of the L1, L2, and L3 oriented films were all 0.20mm. The electromagnetic shielding performance of the composite pressure-sensitive adhesive is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding performance of the composite pressure-sensitive adhesive can reach 90.17dB, the absorption loss accounts for 88.29 percent of the total shielding performance, and the peel strength is 1.19N/mm. The properties of the materials are listed in table 1.

Comparative example 1:

comparative example 26, only the mixed solution S1 was prepared, and an L1 alignment film was prepared using a 1.2T static magnetic field with parallel base films. During casting, the height of the doctor blade was controlled so that the thickness of the L1 oriented film was 0.45mm. The electromagnetic shielding performance of the L1 oriented film is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding performance of the L1 oriented film can reach 33.65dB, the absorption loss accounts for 44.23% of the total shielding performance, and the peeling strength is 0.61N/mm. The properties of the materials are listed in table 1.

Comparative example 2:

in comparative example 26, only the mixed solution S2 was prepared, and an L2 alignment film was prepared using a 1.2T static magnetic field having an angle of 60 ° with respect to the horizontal plane. During casting, the blade height was controlled so that the thickness of the L2 oriented film was 0.45mm. The electromagnetic shielding performance of the L2 oriented film is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding performance of the L2 oriented film can reach 36.17dB, the absorption loss accounts for 45.96% of the total shielding performance, and the peeling strength is 0.62N/mm. The properties of the materials are listed in table 1.

Comparative example 3:

comparative example 26, only the mixed solution S3 was prepared, and an L3 alignment film was prepared using a 1.2T static magnetic field perpendicular to the base film. During casting, the blade height was controlled so that the thickness of the L3 oriented film was 0.45mm. The electromagnetic shielding performance of the L3 oriented film is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding efficiency of the L3 oriented film can reach 32.34dB, the absorption loss accounts for 43.49 percent of the total shielding efficiency, and the peel strength is 0.61N/mm. The properties of the materials are listed in table 1.

Comparative example 4:

by selecting the method in patent CN 110408342A as comparison in example 5, the carbon nanosphere-filled double-cured double-sided conductive adhesive tape with the thickness of 0.45mm is prepared. The electromagnetic shielding performance of the double-curing double-sided conductive adhesive tape is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding performance of the double-curing double-sided conductive adhesive tape is 35.33dB, the absorption loss accounts for 36.78% of the total shielding performance, and the peel strength is 0.60N/mm. The properties of the materials are listed in table 1.

Comparative example 5:

the method is as in example 26, and the carbon nanospheres are replaced by the hammer-shaped nickel powder with the average chain length of 57.0 μm and the flake nickel powder with the average flake diameter of 49.0 μm to prepare the double-cured double-sided conductive adhesive tape with the thickness of 0.45mm, wherein the mass ratio of the hammer-shaped nickel powder to the flake nickel powder is 3:2, the mass ratio of nickel powder to polyacrylate in the prepared double-curing double-sided conductive adhesive tape is 1:1. the electromagnetic shielding performance of the double-curing double-sided conductive adhesive tape is tested by a vector network analyzer under the frequency of 8.2-12.4GHz by using a waveguide method, the electromagnetic shielding performance of the double-curing double-sided conductive adhesive tape is 38.47dB, the absorption loss accounts for 38.03% of the total shielding performance, and the peel strength is 0.60N/mm. The properties of the materials are listed in table 1.

Comparative example 6:

the method of patent CN 103525340A in example 3 was selected as a comparison, and the electromagnetic shielding adhesive film with a thickness of 0.45mm was prepared by using the method. The electromagnetic shielding performance of the electromagnetic shielding film is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, and the electromagnetic shielding film is tested to have the electromagnetic shielding effectiveness of 18.63dB, the absorption loss of 26.96 percent of the total shielding effectiveness and the peel strength of 0.57N/mm. The properties of the materials are listed in table 1.

Comparative example 7:

the method is as in example 26, and the hammer nickel powder with the average chain length of 57.0 μm and the flake nickel powder with the average flake diameter of 49.0 μm are compounded to be used as the electromagnetic shielding particles to prepare the electromagnetic shielding adhesive film with the thickness of 0.45mm, wherein the mass ratio of the hammer nickel powder to the flake nickel powder is 3:2, the mass ratio of the nickel powder in the prepared electromagnetic shielding adhesive film to the solid content in the water-soluble epoxy modified acrylate resin adhesive is 1:1. the electromagnetic shielding performance of the double-curing double-sided conductive adhesive tape is tested by a vector network analyzer by using a waveguide method at the frequency of 8.2-12.4GHz, the electromagnetic shielding performance of the double-curing double-sided conductive adhesive tape is 22.38dB, the absorption loss accounts for 30.93% of the total shielding performance, and the peel strength is 0.59N/mm. The properties of the materials are listed in table 1.

Through the examples 1 to 5, it can be seen that when the average chain length of the hammer-shaped nickel powder disclosed by the invention is 57.0 to 70.0 μm, and the average flake diameter of the flake nickel powder is 49.0 to 68.0 μm, the electromagnetic shielding effectiveness and the absorption loss of the prepared composite pressure-sensitive adhesive account for higher percentage of the total shielding effectiveness.

Through the embodiments 6 to 13, it can be seen that when the metal functional filler disclosed by the invention is oriented at 50 to 70 degrees with the horizontal plane in the middle layer, the electromagnetic shielding effectiveness and the absorption loss of the prepared composite pressure-sensitive adhesive account for higher percentage of the total shielding effectiveness.

From examples 14 to 17, it can be seen that the mass ratio of the intermediate layer sphere nickel powder to the flake nickel powder disclosed in the present invention is in the range of 1.5 to 4: within the range of 1, the prepared composite pressure-sensitive adhesive has higher electromagnetic shielding effectiveness, absorption loss percentage of the total shielding effectiveness and peeling strength.

Through the example 14 and the examples 18 to 25, it can be seen that the solid content of the acrylate pressure-sensitive adhesive disclosed by the invention is in the range of 30.0 to 45.0wt.%, and the mass ratio of each layer of the metal functional filler to the solid content of the layer of the pressure-sensitive adhesive is 1 to 2:1, the electromagnetic shielding effectiveness, the percentage of absorption loss in the total shielding effectiveness and the peeling strength of the prepared composite pressure-sensitive adhesive are higher.

Through the embodiment 14 and the embodiments 26 to 27, it can be seen that the thickness of each layer of the composite pressure sensitive adhesive disclosed by the invention is in the range of 0.15 to 0.2mm, and the electromagnetic shielding effectiveness, the percentage of absorption loss in the total shielding effectiveness and the peel strength are higher.

Through comparison between examples 26 to 27 and comparative examples 1 to 3, it can be seen that the electromagnetic shielding effectiveness, the percentage of absorption loss in the total shielding effectiveness, and the peel strength of the multilayer composite pressure-sensitive adhesive of different oriented metal functional fillers disclosed by the invention are superior to those of the composite pressure-sensitive adhesive of single oriented metal functional filler.

By comparing examples 26 to 27 with comparative examples 4 to 7, it can be seen that the electromagnetic shielding effectiveness, the percentage of absorption loss in the total shielding effectiveness and the peel strength of the multilayer composite pressure-sensitive adhesive of the different oriented metal functional fillers disclosed by the invention are superior to those of the prior art.

TABLE 1 comparison of the Properties of the inventive and comparative examples

Claims

1. The composite pressure-sensitive adhesive with the oriented structure and the electromagnetic shielding function is characterized by having a three-layer structure, namely an upper layer, a middle layer and a lower layer, and mainly comprising two parts, namely acrylate pressure-sensitive adhesive and metal magnetic filler, wherein the metal magnetic filler has different oriented structures in the thickness direction of each layer;

the metal magnetic filler is oriented parallel to the base film direction inside the lower layer and oriented at an angle α to the horizontal plane inside the intermediate layer, wherein 0 ° < α <90 ° or 90 ° < α <180 °, is oriented perpendicular to the base film direction inside the upper layer;

the initial viscosity of the acrylate pressure-sensitive adhesive is 3000-5000 CPS, and the peel strength is 1.20-1.50N/mm;

the metal magnetic filler is formed by compounding hammer ball nickel powder and flake nickel powder; wherein the average chain length of the hammer-shaped nickel powder is 16.0-70.0 μm, and the average flake diameter of the flake nickel powder is 22.0-68.0 μm;

in the intermediate layer, the mass ratio of the hammer nickel powder to the flake nickel powder is 1 to 8:1.

2. the composite pressure-sensitive adhesive with the oriented structure and the electromagnetic shielding function according to claim 1, wherein the acrylate pressure-sensitive adhesive accounts for 45.5-87.0 wt.% of the composite pressure-sensitive adhesive with the electromagnetic shielding function, and the metal magnetic filler accounts for 13.0-54.5 wt.% of the composite pressure-sensitive adhesive with the electromagnetic shielding function.

3. The composite pressure-sensitive adhesive with the oriented structure and the electromagnetic shielding function is characterized in that the solid content of the acrylate pressure-sensitive adhesive is 30.0-60.0 wt.%, and the mass ratio of the metal magnetic filler to the solid content of each layer of the composite pressure-sensitive adhesive with the electromagnetic shielding function is 1-2: 1 to 2.

4. The composite pressure-sensitive adhesive with electromagnetic shielding function and orientation structure of any one of claims 1-3, wherein the thickness of each layer of the composite pressure-sensitive adhesive with electromagnetic shielding function is 0.10-0.20 mm.

5. The method for preparing the electromagnetic shielding function composite pressure-sensitive adhesive with the orientation structure as claimed in any one of claims 1 to 4, wherein the orientation structure is constructed by combining an external static magnetic field and solution casting, and the following are sequentially formed on the surface of a base film:

an oriented base film layer L1, i.e., a lower layer, in which the metal magnetic filler is oriented parallel to the base film direction; an oriented film layer L2 in which the metal magnetic filler is oriented at an angle alpha relative to the base film direction, namely an intermediate layer; and an orientation film layer L3, i.e., an upper layer, in which the metal magnetic filler is oriented in a direction perpendicular to the base film.

6. The preparation method according to claim 5, characterized by comprising the following steps:

(1) Adding the flaky nickel powder into acrylate pressure-sensitive adhesive, stirring, and defoaming to prepare mixed solution S1 and S3;

(2) Adding the hammer nickel powder and the flake nickel powder into acrylate pressure-sensitive adhesive, stirring, and defoaming to prepare a mixed solution S2;

(3) Casting the mixed solution S1 on the surface of a horizontally placed polyethylene base film, then placing the polyethylene base film into a static magnetic field, orienting the polyethylene base film in a direction parallel to the direction of the base film for 3-4h, and then placing the polyethylene base film into an oven for drying to obtain an L1 oriented film;

(4) After the mixed solution S1 is completely dried, casting a mixed solution S2 on the air side surface of the L1 orientation film, then placing the mixed solution into a static magnetic field, wherein the direction of the magnetic field and the horizontal plane form an alpha angle, wherein the alpha is more than 0 degrees and less than 90 degrees or more than 90 degrees and less than 180 degrees, the orientation time is 3-4h, and then placing the mixed solution into an oven for drying to obtain an L1+ L2 orientation film;

(5) And after the mixed solution S2 is completely dried, casting the mixed solution S3 on the surface of the air side of the L2 surface of the obtained L1+ L2 oriented film, then placing the mixed solution into a static magnetic field, wherein the direction of the magnetic field is vertical to the direction of the base film, the orientation time is 3-4h, then placing the mixed solution into an oven for drying, and after the mixed solution is completely dried, finally obtaining the L1+ L2+ L3 electromagnetic shielding function composite pressure-sensitive adhesive with the orientation structure.

7. The production method according to claim 6, wherein the static magnetic fields of steps (3) to (5) are all 1.2T static magnetic fields.