Isolator sheet and UHF RFID tag

Abstract

The present application provides an isolating sheet, which comprises a resin layer and a plurality of insulating soft magnetic particles dispersed in the resin layer. By adjusting the weight percentage of the insulating soft magnetic particles in the isolating sheet, the product of the dielectric constant imaginary part, the dielectric quality factor, the magnetic permeability real part and the magnetic quality factor of the isolating sheet is between 3000 and 4500, so as to achieve the effect of matching the electrical and magnetic properties in the isolating sheet of single-layer structure. Moreover, even if the thickness of the isolating sheet is less than 0.5 mm, the UHF RFID reader can still read the information stored in the antenna of the UHF RFID tag under the working frequency range of 860 MHz-960 MHz. The present application also provides a manufacturing method of the aforementioned isolating sheet, so as to make the isolating material in the form of flexible roll, which is convenient for printing and adhering with the antenna of the UHF RFID tag, and therefore has high practical value. The present application also provides a UHF RFID tag comprising the aforementioned isolating sheet.

Description

Technical Field

[0001] This invention relates to an isolation sheet, its preparation method, and a UHF RFID tag using the same isolation sheet, for reducing interference from metal objects attached to or near the tag when the RFID tag is in an ultra-high frequency (UHF) radio frequency environment. Background Technology

[0002] Ultra-high frequency (UHF) refers to electromagnetic waves with frequencies ranging from 300MHz to 3GHz. UHF is widely used in technologies related to Radio Frequency Identification (RFID) tags, such as in warehouse management. "UHF RFID tag" refers to an RFID tag that can operate in the UHF frequency band. This is because UHF RFID tags have non-contact sensing characteristics and a wide reading range. Furthermore, in a UHF radio frequency environment, one UHF RFID reader (or RFID reader / writer) can read multiple UHF RFID tags at once, thus reducing operation time.

[0003] When a UHF RFID tag is attached to or near the surface of a non-metallic product, such as a plastic basin, the UHF RFID reader can begin reading the tag from a relatively far distance; this is called the "initial reading distance." However, when a UHF RFID tag is attached to or near a metallic product, such as a stainless steel or aluminum pot on a warehouse or shelf, or a PET or glass bottle containing water, the input impedance of the UHF RFID tag will rapidly attenuate because the tag is located on the surface of the metal, PET, or glass bottle. In this situation, the UHF RFID reader must be closer than the "initial reading distance" to have a chance to read the tag; this is called the "farthest reading distance," which is the furthest distance from the UHF RFID tag that can be read as you move away from it. Beyond this distance, the UHF RFID tag cannot be read. Therefore, the "original reading distance" of a UHF RFID tag when attached to or near a non-metallic surface is greater than the "farthest reading distance" when attached to or near a metallic surface. Sometimes, the input impedance attenuation of the UHF RFID tag is so severe that it cannot be read, and in this case, the "farthest reading distance" will be marked as zero.

[0004] Currently, to overcome the aforementioned problems when UHF RFID tags are attached to or near metal objects, a spacer is typically placed between the metal object and the UHF RFID tag to create an isolation effect and reduce the impact of the metal object on the maximum reading distance. For example, Document 1 (Chinese Patent Publication No. CN109713427B) uses a multi-layer composite of polymer film and foam medium layer as the spacer. However, the thickness of the foam medium layer alone must be greater than 0.5 mm to achieve an isolation effect (meaning that the UHF RFID reader can read the data from the UHF RFID tag), and the double-layer design results in a complicated and difficult manufacturing process. In addition, Document 2 (Chinese Patent Publication No. CN103401055B) uses a single-layer design with magnetic material as the spacer to improve the aforementioned problems of Document 1; however, the same problem also appears in Document 2. The thickness of the magnetic material must be greater than 0.5 mm to achieve an isolation effect, and at this time the maximum reading distance is only 1.5 m. Even if the thickness of the magnetic material is increased to 5 mm, the maximum reading distance is still only 5 m.

[0005] With the miniaturization of both metal products and UHF RFID tags, the thickness of the isolation sheet has become extremely critical, meaning it must be reduced. The isolation sheets with a thickness greater than 0.5 mm used in References 1 and 2 are no longer sufficient for industry needs. In fact, industry is already facing the need to read UHF RFID tags even with an isolation sheet thickness of less than 0.5 mm.

[0006] Although Reference 2 records the numerical ranges of the real and imaginary parts of the dielectric constant and the loss tangent, as well as the numerical ranges of the real and imaginary parts of the permeability and the loss tangent, Reference 2 does not notice the mutual influence between the dielectric constant and the permeability. This is a major factor that makes Reference 2 unable to break through and reduce the thickness of the separator to less than 0.5 mm and still allow the UHF RFID tag to be read. Summary of the Invention

[0007] The insulating sheet provided by the inventor, even when its thickness is less than 0.5 mm and when applied between the back of the antenna of a UHF RFID tag and a metal object, allows a UHF RFID reader located in front of the antenna of the UHF RFID tag and at a predetermined distance from the antenna to still read the information stored in the UHF RFID tag within the operating bandwidth of 860MHz~960MHz, thus achieving the effect of thinness; moreover, the insulating sheet is a single-layer structure integrally molded, meaning it is not assembled (without) This refers not to an assembly, but rather to a single process, thus simplifying the manufacturing process. Furthermore, the separator is composed of a resin layer and multiple insulating soft magnetic particles dispersed within the resin layer. The insulating soft magnetic particles are spherical in shape, and their weight percentage can be adjusted so that the product of the real part of the dielectric constant (ε'), the dielectric mass factor (Qε), the real part of the permeability (μ'), and the magnetic mass factor (Qμ) of this single-layer structure falls between two predetermined values. This achieves the effect of simultaneously matching electrical and magnetic properties within the single-layer structure. The dielectric mass factor (Qε) and the magnetic mass factor (Qμ) will be explained later.

[0008] The inventors provide an insulating sheet comprising a resin layer and a plurality of insulating soft magnetic particles dispersed in the resin layer; the insulating sheet has a real part of dielectric constant (ε'), an imaginary part of dielectric constant (ε''), a dielectric quality factor (Qε), a real part of permeability (μ'), an imaginary part of permeability (μ''), and a magnetic quality factor (Qμ), wherein the dielectric quality factor (Qε) is the quotient obtained by dividing the real part of dielectric constant (ε') by the imaginary part of dielectric constant (ε''), and the magnetic quality factor (Qμ) is the quotient obtained by dividing the real part of permeability (μ') by the imaginary part of permeability (μ''); wherein the product of the real part of dielectric constant (ε'), the dielectric quality factor (Qε), the real part of permeability (μ'), and the magnetic quality factor (Qμ) is between 3000 and 4500.

[0009] In one embodiment of the insulating sheet, the product of the real part of the dielectric constant (ε'), the dielectric quality factor (Qε), the real part of the permeability (μ'), and the magnetic quality factor (Qμ) is between 3522.40 and 4460.50.

[0010] In one embodiment of the insulating sheet, the product of the real part of the dielectric constant (ε'), the dielectric quality factor (Qε), the real part of the permeability (μ'), and the magnetic quality factor (Qμ) is between 3550 and 4000.

[0011] In one embodiment of the insulating sheet, the real part of the dielectric constant (ε') is between 10 and 20, the imaginary part of the dielectric constant (ε'') is between 0.8 and 1.5, the real part of the permeability (μ') is between 5.0 and 6.5, the imaginary part of the permeability (μ'') is between 1.0 and 2.5, the dielectric quality factor (Qε) is between 10 and 20, and / or the magnetic quality factor (Qμ) is between 2.0 and 5.0.

[0012] In one embodiment of the insulating sheet, the real part of the dielectric constant (ε') is between 11.15 and 16.53, the imaginary part of the dielectric constant (ε'') is between 0.8 and 1.33, the real part of the permeability (μ') is between 5.23 and 6.12, the imaginary part of the permeability (μ'') is between 1.23 and 2.42, the dielectric quality factor (Qε) is between 12.43 and 19.50, and / or the magnetic quality factor (Qμ) is between 2.16 and 4.69, the product of the real part of the dielectric constant (ε') and the dielectric quality factor (Qε) can be between 155.40 and 311.81, and / or the product of the real part of the permeability (μ') and the magnetic quality factor (Qμ) can be between 11.30 and 28.70.

[0013] In one embodiment of the insulating sheet, the insulating soft magnetic particle is spherical in shape, having a core and a shell surrounding the core; the core is a soft magnetic core made of a soft magnetic material, which is a carbonyl iron powder ball; and the shell is made of an insulating material, with a phosphate film and a silicate film sequentially covering the core from the inside out.

[0014] In one embodiment of the insulating sheet, a plurality of insulating soft magnetic particles account for 70wt% to 87wt% of the insulating sheet, the resin layer is composed of a resin material, the resin material accounts for 13wt% to 30wt% of the insulating sheet, the resin material and the plurality of insulating soft magnetic particles together account for 100wt% of the insulating sheet, and the particle size of the insulating soft magnetic particles is between 1μm and 5μm.

[0015] In one embodiment of the insulating sheet, a plurality of the insulating soft magnetic particles account for 70wt% to 77.5wt% of the insulating sheet, and the resin material accounts for 22.5wt% to 30wt% of the insulating sheet.

[0016] In one embodiment, the isolation sheet is a single-layer structure integrally formed.

[0017] The inventors also provide a UHF RFID tag, comprising an antenna and an isolation piece as described above disposed below the antenna.

[0018] In one embodiment of the UHF RFID tag, the thickness of the isolation sheet is less than 0.5 mm.

[0019] In one embodiment, a UHF RFID tag is provided, wherein the UHF RFID tag and / or the isolating sheet are suitable for an operating bandwidth of 860MHz to 960MHz.

[0020] The inventors further provide a method for manufacturing an isolation sheet, which involves weighing and mixing a thermoplastic elastomer with multiple insulating soft magnetic particles, then calendering the mixture into a flexible roll for easy printing and bonding with the antenna of a UHF RFID tag, and subsequently cutting it into sheet-like isolation sheets. Because a thickness of less than 0.5mm is more conducive to making flexible rolls (commonly known as rolls, i.e., rolled materials), automated tag bonding is possible, making it suitable for mass production.

[0021] In one embodiment of the method for manufacturing an insulating sheet, a plurality of insulating soft magnetic particles account for 70wt% to 87wt% of the insulating sheet, a thermoplastic elastomer accounts for 13wt% to 30wt% of the insulating sheet, the thermoplastic elastomer and the plurality of insulating soft magnetic particles together account for 100wt% of the insulating sheet, and the particle size of the insulating soft magnetic particles is between 1μm and 5μm.

[0022] A method for manufacturing a separator sheet in one embodiment, wherein the thickness of the separator sheet is less than 0.5 mm.

[0023] In summary, the inventors have developed a flexible, integrally molded single-layer insulating sheet made of insulating soft magnetic particles and thermoplastic elastomer. By adjusting the weight percentage of the insulating soft magnetic particles in the insulating sheet, the product of the real part of the dielectric constant (ε'), dielectric mass factor (Qε), real part of the permeability (μ'), and magnetic mass factor (Qμ) of this single-layer structure is between two predetermined values, thereby achieving the effect of simultaneously matching electrical and magnetic properties in the single-layer insulating sheet. Furthermore, even when the insulating sheet is less than 0.5 mm thick and is applied between the back of the UHF RFID tag antenna and a metal object, a UHF RFID reader located in front of the UHF RFID tag antenna and at a predetermined distance from the antenna can still read the information stored in the UHF RFID tag antenna within the 860MHz~960MHz operating bandwidth. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the isolation sheet, UHF RFID tag, and their application in metal products according to the present invention.

[0025] Figure 2 This is a diagram illustrating the usage status of the UHF RFID tag of this invention in metal products.

[0026] Figure 3 This is a comparison graph showing the relationship between the furthest reading distance and frequency of the isolation sheet using the present invention and commercially available isolation sheets at the operating bandwidth.

[0027] Drawing number explanation:

[0028] 3: UHF RFID tags

[0029] 31: Antenna

[0030] 32: Isolation film

[0031] 321: Resin layer

[0032] 322: Insulating soft magnetic particles

[0033] 3221: Core

[0034] 3222: Shell

[0035] 4: UHF RFID tag reader

[0036] M: Metal products. Detailed Implementation

[0037] To make the description of the present invention more detailed and complete, illustrative descriptions of embodiments and specific examples of the present invention are provided below; however, this is not the only form of implementing or applying the specific examples of the present invention. Furthermore, in this specification and the claims, the use of “~” and “between… and…” to indicate a numerical range refers to the range encompassing the values ​​recorded before and after “~” and “… and…” as the lower and upper limits, respectively; the use of “wt%” in this specification and the claims refers to weight percentage; the use of “particle size” in this specification and the claims refers to the particle size measured using a laser particle size analyzer.

[0038] <Structure of the isolation sheet and UHF RFID tag>

[0039] Please see Figure 1 As shown, the insulating sheet 32 ​​provided by the present invention is disposed between an antenna 31 of a UHF RFID tag 3 and a metal product M. In other words, the UHF RFID tag 3 includes the antenna 31 and the insulating sheet 32 ​​disposed below the antenna 31. The insulating sheet 32 ​​includes a resin layer 321 and a plurality of insulating soft magnetic particles 322 dispersed in the resin layer 321.

[0040] The resin layer 321 is composed of a resin material, which can be a thermoplastic polyurethane elastomer or a thermoplastic polyolefin elastomer, and the resin material accounts for 13wt% to 30wt% of the separator.

[0041] The insulating soft magnetic particle 322 is spherical in shape, having a core 3221 and a shell 3222 surrounding the core 3221. The core 3221 is a soft magnetic core made of a soft magnetic material, specifically carbonyl iron powder spheres. The shell 3222 is made of an insulating material, and is sequentially coated from the inside out with a phosphate film and a silicate film. The phosphate film comprises 0.5wt% to 5wt% of the core 3221, and the silicate film comprises 0.5wt% to 3wt%. The particle size of the insulating soft magnetic particle 322 is between 1μm and 5μm. Multiple insulating soft magnetic particles 322 account for 70wt% to 87wt% of the insulating sheet. Preferably, the resin material and the plurality of insulating soft magnetic particles together account for 100 wt% of the insulating sheet.

[0042] <Manufacturing Method of Isolation Plates>

[0043] Thermoplastic polyurethane elastomer and insulating soft magnetic particles [three types were used in the examples, with a core of spherical carbonyl iron powder and a shell of different proportions (A), (B), and (C)] were weighed and mixed according to the proportions listed in Table 1 below (wt%). The mixture was then placed in an internal mixer for kneading until a uniform compound was formed. The compound was then discharged. Next, the compound was calendered into flexible rolls according to the thicknesses listed in Tables 1 and 2 below using a calender. These rolls were then cut into sheets to prepare the separator sheets of Examples 1-3 and Comparative Examples 1-2. Therefore, the separator sheets are integrally molded single-layer structures. "Integrated molding" means without assembly, but rather formed by the same process (calender). Comparative Examples 1-2 used insulating soft magnetic particles (D) and (E) with a core of sheet-like iron-silicon-chromium (FeSiCr) instead of spherical carbonyl iron powder.

[0044] <Effect Evaluation and Testing of Isolation Panels>

[0045] Please see Figure 2The isolation sheet 32 ​​(length*width 57*19mm) of the embodiment and comparative example was placed between the antenna 31 of the UHF RFID tag 3 [F-type UHF TAG (IFA Tag) length*width 57*19mm] and the metal product M, so that the antenna 31, the single-layer isolation sheet 32 ​​and the metal product M were in close contact. Then, according to ASTM D7449, the electromagnetic data in Table 1 below were obtained by measuring with the network analyzer KEYSIGHT 5071C and N1500A material quality measurement software. The maximum reading distance was measured by the Tagformance Pro testing instrument produced by Voyantic, Finland, at an operating frequency of 915MHz and recorded in Tables 1 and 2 below. If the maximum reading distance is exceeded, the instrument cannot read the UHF RFID tag data. It should be noted that the farthest distance at which the instrument can read UHF RFID tag data without metal interference is taken as the original reading distance, which is 3.76m. The "recovery percentage" in Table 1 refers to the quotient obtained by dividing the farthest reading distance by the original reading distance and expressed as a percentage. Based on the shortcomings of Documents 1 and 2, a stricter standard for the isolation sheet than that of Documents 1 and 2 is set. Therefore, this invention sets a recovery percentage greater than 40% or a farthest reading distance greater than 1.50m as acceptable when the isolation sheet thickness is 0.5mm. When the isolation sheet thickness is 0.5mm, a recovery percentage greater than 15% or a farthest reading distance greater than 0.5m is acceptable. It should also be noted that the isolation sheet of this invention, in other possible embodiments (examples not listed below), can also be placed between the antenna [monopole tag] of the UHF RFID tag and a metal object for testing. Alternatively, it can be measured at an operating frequency of 866MHz. In other words, the isolation plate of the present invention is suitable for measurement in operating bandwidths of 860MHz to 960MHz.

[0046] Table 1

[0047]

[0048] In Table 1, ε' is the real part of the dielectric constant, ε'' is the imaginary part of the dielectric constant, Qε is the dielectric quality factor, μ' is the real part of the permeability, μ'' is the imaginary part of the permeability, and Qμ is the magnetic quality factor. The dielectric quality factor (Qε) is the quotient obtained by dividing the real part of the dielectric constant (ε') by the imaginary part of the dielectric constant (ε''), and the magnetic quality factor (Qμ) is the quotient obtained by dividing the real part of the permeability (μ') by the imaginary part of the permeability (μ''). ε'×Qε represents the product of the real part of the dielectric constant (ε') and the dielectric quality factor (Qε), and μ'×Qμ represents the product of the real part of the permeability (μ') and the magnetic quality factor (Qμ).

[0049] As shown in Table 1, in Examples 1-3, with a separator thickness of 0.5mm, the recovery percentage is greater than 40%, and the maximum reading distance is greater than 1.50m, so they are qualified products. In Comparative Examples 1-2, with a separator thickness of 0.5mm, the recovery percentage is less than 40%, and the maximum reading distance is less than 1.50m, so they are unqualified products. Further, Table 1 shows that the "electromagnetic factors" of Examples 3, 2, and 1 are 3522.40, 3834.82, and 4460.50, respectively. The electromagnetic factor is the product of the real part of the dielectric constant (ε'), the dielectric mass factor (Qε), the real part of the permeability (μ'), and the magnetic mass factor (Qμ). Therefore, the electromagnetic factor of the separator of the present invention is between 3000 and 4500, preferably between 3522.40 and 4460.50, and more preferably between 3550 and 4000. As shown in Table 1, the higher the electromagnetic factor, the higher the recovery percentage. For example, the electromagnetic factors in Examples 3, 2, and 1 gradually increase from 3522.40 to 4460.50, and the recovery percentages also gradually increase from 40.2% to 51.3% to 53.1%. Therefore, the electromagnetic factor and the recovery percentage described in this invention are highly positively correlated. In other words, a separator with a specific thickness and recovery percentage can be designed based on the electromagnetic factor, which is a major innovation of this invention. The "electromagnetic factor" indicates that the separator of this invention takes into account both electrical and magnetic effects in a single-layer structure, rather than a multi-layer structure where each layer only considers electrical or magnetic effects before being stacked and assembled.

[0050] Additionally, ε' can be between 10 and 20, ε'' can be between 0.8 and 1.5, μ' can be between 5.0 and 6.5, μ'' can be between 1.0 and 2.5, Qε can be between 10 and 20, and / or Qμ can be between 2.0 and 5.0. As can also be seen from Table 1, preferably, ε' can be between 11.15 and 16.53, ε'' can be between 0.8 and 1.33, μ' can be between 5.23 and 6.12, μ'' can be between 1.23 and 2.42, Qε can be between 12.43 and 19.50, Qμ can be between 2.16 and 4.69, the product of ε' and Qε can be between 155.40 and 311.81, and / or the product of μ' and Qμ can be between 11.30 and 28.70.

[0051] In addition, preferably, the plurality of insulating soft magnetic particles account for 70wt% to 77.5wt% of the insulating sheet, and the resin material accounts for 22.5wt% to 30wt% of the insulating sheet, and the resin material and the plurality of insulating soft magnetic particles together account for 100wt% of the insulating sheet.

[0052] <Unintended Effect 1>

[0053] Using the thermoplastic polyurethane elastomer and insulating soft magnetic particles of Example 1 in Table 1, insulating sheets of different thicknesses were made according to Table 2 below, and the farthest reading distance and recovery percentage were measured according to the aforementioned method and equipment.

[0054] Table 2

[0055]

[0056] When the isolation plate thickness is 1.0 mm, the recovery percentage can reach 100%, and the maximum reading distance has recovered to 3.76 m (i.e., the aforementioned "original reading distance" of the UHF RFID tag). However, an unexpected finding from Table 2 is that when the isolation plate thickness reaches 2.0 mm and 3.0 mm, the maximum reading distance exceeds 3.76 m, reaching 5.82 m and 7.33 m respectively, which translates to recovery percentages of 154.7% and 194.7% respectively. In other words, it is a surprising discovery that when the isolation plate thickness of the present invention exceeds a certain thickness, the isolation plate will produce a gain effect, causing the maximum reading distance to exceed or be greater than the original reading distance. This breaks through the limitations mentioned in previous technologies or literature, which all believed that the maximum reading distance could not be greater than the original reading distance.

[0057] Table 2 further shows that when the isolation sheet thickness is 0.4 mm, the recovery percentage is 42.4%, which is greater than the acceptable standard of 40%, and the maximum reading distance is 1.60 m, which is also greater than the acceptable standard of 1.50 m. In other words, it is surprising to find that the isolation sheet of the present invention has broken through the limitations mentioned in Documents 1 and 2 of the prior art, which both believed that the isolation sheet must be larger than 0.5 mm for the UHF RFID reader to read the data of the UHF RFID tag.

[0058] Table 2 further shows that even with a separator thickness of 0.1 mm, UHF RFID tag data can still be read at a distance of 0.33 m, even with a recovery percentage of only 8.7%. In other words, it is surprising to find that the separator of the present invention has overcome the limitations mentioned in prior art documents 1 and 2, which both stated that when the separator is less than 0.5 mm, the UHF RFID reader cannot read the UHF RFID tag data.

[0059] <Unintended Effect 2>

[0060] Based on the fact that the commercially available isolation sheet (composition unknown) obtained had a thickness of 5mm, an isolation sheet with a thickness of 5mm as described in Example 1 was specifically used. The aforementioned instruments and methods for "Effect Evaluation and Testing of Isolation Sheets" were used for testing, but the operating bandwidth was changed to 850MHz~950MHz. The test results were then plotted... Figure 3 .

[0061] Depend on Figure 3 It can be seen that the UHF RFID tag using the isolator of Embodiment 1 has a longer maximum reading distance than the UHF RFID tag using a commercially available isolator. For example, when the distance between the UHF RFID tag reader and the antenna of the UHF RFID tag is 4 to 5.5 meters, the antenna data using a commercially available isolator cannot be read by the UHF RFID tag reader at any frequency within the operating bandwidth of 850MHz to 950MHz; however, the antenna data using the isolator of Embodiment 1 can be read by the UHF RFID tag reader at any frequency within the operating bandwidth of 850MHz to 950MHz. Obviously, within a specific distance from the antenna, compared to commercially available isolators, the UHF RFID tag using the isolator of this invention allows the antenna data to be read at any frequency within the operating bandwidth of 850MHz to 950MHz in actual operation, achieving the effect of "full-bandwidth" antenna data reading.

[0062] In addition, by Figure 3Furthermore, the plot of the "maximum reading distance / frequency" for commercially available isolation sensors shows a curve with a peak, which appears at 905MHz. For example, when the distance between the UHF RFID tag reader and the UHF RFID tag antenna is 2 meters, it means that antenna data can only be read at frequencies near the peak value of 905MHz. Data cannot be read at frequencies far from 905MHz, such as 890MHz and 930MHz, thus limiting the ability to read antenna data and resulting in a narrower actual operating bandwidth. If one wants to read antenna data at a maximum reading distance of approximately 1.5 meters using 890MHz or 930MHz, the UHF RFID tag reader must be moved to a distance of less than 1.5 meters, or the RFID tag reader must be restricted to being directly in front of the antenna without being offset at a certain angle, resulting in a straight-line distance exceeding approximately 1.5 meters. This causes inconvenience in data reading and therefore poor stability. However, in contrast, the plot of "farthest reading distance / frequency" using the isolator of Example 1 shows a "flat area" in the 890MHz to 950MHz range. This makes its actual operating bandwidth far exceed the 890MHz to 950MHz range, and its actual operating bandwidth is wider than that of UHF RFID tags using commercially available isolators. Moreover, it does not require the UHF RFID tag reader to be restricted to the front of the antenna, and it can still read antenna data even if it is offset at a certain angle, so its stability is also higher.

[0063] <Proportion of resin material to insulating soft magnetic particles in the insulating sheet>

[0064] The present invention further produces insulating sheets with different proportions and thicknesses of resin material and insulating soft magnetic particles according to Table 3 below, and measures the farthest reading distance and recovery percentage according to the aforementioned method and equipment.

[0065] Table 3

[0066]

[0067] As previously stated, when the separator thickness is 0.5 mm, a recovery percentage greater than 15% or a maximum reading distance greater than 0.5 m is acceptable. Therefore, in Examples 1-1, 1, 1-2, and 1-3, the recovery percentages measured with a separator thickness of 0.5 mm are all greater than 15%, and the maximum reading distances are all greater than 0.5 m. Therefore, the resin material accounts for 13 wt% to 30 wt% of the separator, the plurality of insulating soft magnetic particles 322 account for 70 wt% to 87 wt% of the separator, and the resin material and the plurality of insulating soft magnetic particles together account for 100 wt% of the separator.

[0068] In summary, the present invention has the following advantages: (1) The electromagnetic factors of the isolation sheet of the present invention are limited to the product of the real part of the dielectric constant (ε'), the dielectric mass factor (Qε), the real part of the permeability (μ'), and the magnetic mass factor (Qμ), which are between 3000 and 4500, preferably between 3522.40 and 4460.50, and more preferably between 3550 and 4000, so as to achieve the effect of matching electrical and magnetic properties in a single-layer structure; (2) When the isolation sheet of the present invention is placed between the antenna of the UHF RFID tag and the metal object, an excellent recovery percentage can be measured; (3) When the thickness of the isolation sheet of the present invention exceeds a certain thickness, the isolation sheet will produce a gain effect, so that the maximum reading distance exceeds or is greater than the original reading distance, breaking through the limitations mentioned in the prior art or literature; (4) The isolation sheet of the present invention has broken through the limitation mentioned in the prior art that the isolation sheet must be greater than 0.5mm; (5) The UHF RFID tag using the isolation sheet of the present invention can be used in UHF RFID tags. When reading antenna data, RFID tag readers have the advantages of high stability and the ability to read antenna data across the entire frequency domain.

Claims

1. A spacer sheet, characterized by, The isolation sheet (32) comprises a resin layer (321) and a plurality of insulating soft magnetic particles (322) dispersed in the resin layer (321); the isolation sheet (32) has a real part of dielectric constant, an imaginary part of dielectric constant, a dielectric quality factor, a real part of magnetic permeability, an imaginary part of magnetic permeability, and a magnetic quality factor; the dielectric quality factor is the quotient of the real part of dielectric constant divided by the imaginary part of dielectric constant; the magnetic quality factor is the quotient of the real part of magnetic permeability divided by the imaginary part of magnetic permeability; the product of the real part of dielectric constant, the dielectric quality factor, the real part of magnetic permeability, and the magnetic quality factor is between 3522.40 and 4460.50; the real part of dielectric constant is between 11.15 and 16.53, the imaginary part of dielectric constant is between 0.8 and 1.33, the real part of magnetic permeability is between 5.23 and 6.12, the imaginary part of magnetic permeability is between 1.23 and 2.42, the dielectric quality factor is between 12.43 and 19.50, and / or the magnetic quality factor is between 2.16 and 4.69; the product of the real part of dielectric constant and the dielectric quality factor can be between 155.40 and 311.81, and / or the product of the real part of magnetic permeability and the magnetic quality factor can be between 11.30 and 28.70; the thickness of the isolation sheet (32) is less than 0.5 mm; the isolation sheet (32) is suitable for an operating frequency range of 860 MHz to 960 MHz; the insulating soft magnetic particles (322) are spherical in shape; the insulating soft magnetic particles (322) have a core portion (3221) and a shell portion (3222) surrounding the core portion (3221); the core portion (3221) is a soft magnetic core portion composed of a soft magnetic material, and the core portion (3221) is a carbonyl iron powder sphere; the shell portion (3222) is composed of an insulating material, and the shell portion (3222) is coated with a phosphate film and a silicate film in order from the inside to the outside of the core portion (3221); the plurality of insulating soft magnetic particles (322) account for 70 wt% to 77.5 wt% of the isolation sheet; the resin layer (321) is composed of a resin material, and the resin material accounts for 22.5 wt% to 30 wt% of the isolation sheet (32); the resin material and the plurality of insulating soft magnetic particles (322) together account for 100 wt% of the isolation sheet (32); the particle size of the insulating soft magnetic particles (322) is between 1 μm and 5 μm; the isolation sheet (32) is a single-layer structure formed in one piece; the resin material is a thermoplastic polyurethane elastomer or a thermoplastic polyolefin elastomer; the isolation sheet (32) is manufactured by weighing the thermoplastic polyurethane elastomer or the thermoplastic polyolefin elastomer and the plurality of insulating soft magnetic particles (322), then mixing and kneading, followed by calendering into a flexible roll-shaped body, and then cutting into the sheet-shaped isolation sheet (32).

2. A UHF RFID tag characterized by The antenna (31) and the isolation sheet (32) as claimed in claim 1 are arranged below the antenna (31).

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