Mixed adhesive for piezoelectric film array sensor and preparation method and application thereof

Abstract

The invention discloses a mixed adhesive and a preparation method thereof, the mixed adhesive is composed of a phenolic resin adhesive and a polyisobutylene adhesive, and the volume ratio of the phenolic resin adhesive to the polyisobutylene adhesive is 1: 1-1: 5. The invention also discloses a piezoelectric film strip array sensor and a preparation method thereof. The piezoelectric film strip array sensor is composed of piezoelectric film strips, a barrier strip, a fastening strip, a protective film and a shielding net. The invention also discloses a method for measuring the flow velocity of a pipeline by using the mixed adhesive or the piezoelectric film strip array sensor, and an application of the mixed adhesive or the piezoelectric film strip array sensor in the measurement of the flow velocity of the pipeline.

Description

Technical Field

[0001] The invention belongs to the field of fluid measurement, and in particular relates to a mixed adhesive for a piezoelectric film array sensor, a preparation method and an application thereof. Background Art

[0002] The pipeline flow velocity measurement sensor based on sonar array technology consists of five parts: a protective film, a fastening belt, a piezoelectric film strip, a barrier belt, and a shielding net. The piezoelectric film can convert the strain signal generated and transmitted by the impact of water flow on the pipeline into an electrical signal without contacting the pipeline, and obtain the water flow velocity after hardware acquisition and algorithm processing. Compared with traditional flow monitoring instruments, pipeline flow velocity test sensors using piezoelectric film have the advantages of non-contact, simple installation, maintenance-free, high measurement accuracy, and strong stability. In 2003, the American CIDRA company developed a pipeline flow velocity test sensor for pipeline flow monitoring. In comparison, my country's research work in this field started late and the content is relatively small.

[0003] As an important component of piezoelectric film, adhesive mainly plays the role of bonding, isolating the charge conduction between the thin film electrode and the conductive substrate. Since the adhesive is made of viscoelastic material, excessive adhesive thickness will cause large distortion of the strain signal during the transmission process, affecting the signal quality. Compared with sensors installed on a flat surface, the thickness of the adhesive has a greater impact on the signal quality of sensors installed on the curved surface of the pipeline. At the same time, adhesives used for pipeline flow rate test sensors generally have the characteristics of high aspect ratio, large scale, small thickness, and high precision. These characteristics put forward higher requirements on the coating process of the adhesive. Traditional methods such as scraping, roller coating, and spraying cannot meet these requirements, while slit extrusion and photolithography are too expensive. Therefore, there is still an urgent need to develop an adhesive that can produce the corresponding pipeline flow rate test sensor in a cost-effective manner while ensuring sufficient bonding strength, and at the same time needs to have excellent signal quality, life and stability. Summary of the invention

[0004] In order to meet the requirements for adhesives of piezoelectric film sensors and overcome the defects of the prior art, the present invention provides a mixed adhesive and a piezoelectric film array sensor including the mixed adhesive.

[0005] One aspect of the present invention provides a mixed adhesive, which is composed of a phenolic resin adhesive and a polyisobutylene adhesive, wherein the volume ratio of the phenolic resin adhesive to the polyisobutylene adhesive is 1:1 to 1:5.

[0006] In one or more embodiments, the phenolic resin adhesive is selected from phenolic resin VK-25, phenolic resin VK-50 or phenolic resin VK-3; the polyisobutylene adhesive is selected from polyisobutylene PB1400, polyisobutylene PB1300 or polyisobutylene PB950.

[0007] Preferably, the phenolic resin adhesive is a phenolic resin VK-50 type, and the polyisobutylene adhesive is a polyisobutylene PB1300 type. Preferably, the phenolic resin adhesive is a phenolic resin VK-50 type, and the polyisobutylene adhesive is a polyisobutylene PB950 type. Preferably, the phenolic resin adhesive is a phenolic resin VK-50 type, and the polyisobutylene adhesive is a polyisobutylene PB1400 type. Preferably, the phenolic resin adhesive is a phenolic resin VK-3 type, and the polyisobutylene adhesive is a polyisobutylene PB1300 type. Preferably, the phenolic resin adhesive is a phenolic resin VK-3 type, and the polyisobutylene adhesive is a polyisobutylene PB950 type. Preferably, the phenolic resin adhesive is a phenolic resin VK-3 type, and the polyisobutylene adhesive is a polyisobutylene PB1400 type. Preferably, the phenolic resin adhesive is phenolic resin VK-25 type, and the polyisobutylene adhesive is polyisobutylene PB1400 type. Preferably, the phenolic resin adhesive is phenolic resin VK-25 type, and the polyisobutylene adhesive is polyisobutylene PB1300 type. Preferably, the phenolic resin adhesive is phenolic resin VK-25 type, and the polyisobutylene adhesive is polyisobutylene PB950 type.

[0008] In one or more embodiments, the volume ratio of the phenolic resin-based adhesive to the polyisobutylene-based adhesive is 1:3.

[0009] Another aspect of the present invention provides a method for preparing a mixed adhesive as described in any embodiment of the present invention, the method comprising: taking a phenolic resin adhesive and a polyisobutylene adhesive in advance, stirring the two at room temperature for 20 to 40 minutes, and standing for use; pouring the phenolic resin adhesive into the polyisobutylene adhesive, stirring at room temperature for 1 to 3 hours, to obtain a mixed adhesive.

[0010] Preferably, in the method, the two are stirred at room temperature for 25 to 35 minutes respectively; more preferably, in the method, the two are stirred at room temperature for 30 minutes respectively.

[0011] Preferably, in the method, the phenolic resin adhesive is poured into the polyisobutylene adhesive and stirred at room temperature for 1.5 to 2.5 hours; more preferably, in the method, the phenolic resin adhesive is poured into the polyisobutylene adhesive and stirred at room temperature for 2 hours.

[0012] Another aspect of the present invention provides a piezoelectric film strip array sensor, which consists of a piezoelectric film strip, a barrier strip, a fastening strip, a protective film and a shielding net; wherein the piezoelectric film strip consists of a metal conductive strip, an adhesive layer, a wire and a piezoelectric sheet, an electrode and a protective layer; fixed guide rails are welded on both sides of the fastening strip; the piezoelectric film strip is bonded to one side of the fastening strip through an adhesive layer, and the protective film is bonded to the other side of the fastening strip; a barrier strip is arranged between the piezoelectric film strips, and the barrier strip is also bonded to the fastening strip; both sides of the shielding net are welded and fixed to the fixed guide rails on the two sides of the fastening strip; the adhesive layer is composed of a mixed adhesive as described in any embodiment of the present invention.

[0013] Preferably, the protective film is composed of a polymer material; more preferably, the protective film material is composed of polyimide.

[0014] Preferably, the fastening belt, the fixing rail and the shielding net are respectively composed of metal materials; more preferably, the fastening belt, the fixing rail and the shielding net are respectively composed of stainless steel.

[0015] Preferably, the barrier tape is composed of a polymer material; more preferably, the barrier tape is composed of one or more components selected from polyether, polyester or polyvinyl alcohol.

[0016] Another aspect of the present invention provides a method for preparing a piezoelectric film strip array sensor, the method comprising the following steps:

[0017] S1: Prepare the stainless steel mold required for screen printing, cut and process rectangular grooves in the mold, and the grooves are evenly distributed at equal distances;

[0018] S2: Place a metal conductive strip in each groove;

[0019] S3: Place the screen flat on the mold so that the screen covers all the strips, pour the mixed adhesive until the mixed adhesive covers the entire screen, and let it stand; after standing, use a scraper to evenly scrape the screen to evenly apply the mixed adhesive to the surface of the metal conductive strip as an adhesive layer; after scraping, let it stand;

[0020] S4: Take out the strip coated with the mixed adhesive, and paste the integrated piezoelectric film module on it to obtain the piezoelectric film strip 1; the piezoelectric film module is composed of a piezoelectric film, an electrode, a protective layer and a wire.

[0021] S5: Bond the piezoelectric film strip to one side of the fastening belt through an adhesive layer, and bond the protective film to the other side of the fastening belt, wherein a fixed guide rail is welded on the fastening belt; a barrier belt is arranged between the piezoelectric film strips, and the barrier belt is bonded to the fastening belt; and then fix the shielding net and the fixed guide rail by welding to obtain a pipeline flow rate test sensor.

[0022] In one or more embodiments, in step S3, the ambient temperature is 0-40° C., and the ambient humidity is 50-70%.

[0023] Preferably, in step S3, the ambient temperature is 5 to 35°C; more preferably, in step S3, the ambient temperature is 10 to 30°C; more preferably, in step S3, the ambient temperature is 15 to 25°C.

[0024] Preferably, in step S3, the ambient humidity is 55-65%; more preferably, in step S3, the ambient humidity is 60%.

[0025] In one or more embodiments, in step S3, each standing time is independently 1 min to 2 h.

[0026] Preferably, in step S3, the standing time before scraping is 0.5 to 1.5 hours.

[0027] Preferably, in step S3, the standing time after scraping is 15 to 25 minutes.

[0028] In one or more embodiments, in step S3, the scraper evenly scrapes the screen at a rate of 0.1-1 mm / s.

[0029] Preferably, in step S3, the scraper evenly scrapes the screen at a rate of 0.4-0.6 mm / s; more preferably, in step S3, the scraper evenly scrapes the screen at a rate of 0.5 mm / s.

[0030] Another aspect of the present invention provides a method for testing pipeline flow rate, the method comprising using the mixed adhesive as described in any embodiment herein or the piezoelectric film strip array sensor as described in any embodiment herein.

[0031] Another aspect of the present invention provides use of the hybrid adhesive as described in any embodiment herein or the piezoelectric film strip array sensor as described in any embodiment herein in pipeline flow velocity measurement.

[0032] The screen printing coating method adopted by the present invention better meets the high aspect ratio, large scale, small thickness, and high-precision coating processing requirements required by the pipeline flow rate test sensor, and has significant cost advantages over coating methods such as slit extrusion and photolithography. In the process of screen printing, most polyurethane glues and silicone glue adhesives often have the characteristics of excessive viscosity and solid content, and too short operating time, which makes it easy to stick to the screen during screen printing, uneven coating, and premature solidification leading to discontinuous coating. The mixed adhesive of phenolic resin and polyisobutylene provided by the present invention, combined with specific screen printing speed and environmental parameters, can effectively avoid the above problems and improve the success rate of coating. In addition, the mixed adhesive provided by the present invention has a strong bonding strength. When used to prepare a pipeline flow rate test sensor, compared with common double-sided adhesives such as polyurethane and silicone grease, the signal quality of flow rate measurement is significantly improved, and it can be comparable to CIDRA's top products of the same type. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a structural breakdown diagram of a piezoelectric film array sensor.

[0034] Figure 2 It is a plan view of a piezoelectric film array sensor.

[0035] Figure 3 is a schematic diagram of the screen printing process of the mixed adhesive.

[0036] Figure 4 This is a diagram of the decomposition of the piezoelectric film strip structure. DETAILED DESCRIPTION

[0037] In order to explain the present invention more clearly, the present invention is further described below in conjunction with preferred embodiments. It should be understood by those skilled in the art that the following specific description is illustrative rather than restrictive, and should not be used to limit the scope of protection of the present invention.

[0038] In the present invention, "signal quality" can be understood as the accuracy of the piezoelectric film sensor in measuring the pipeline flow rate, which is obtained from the secondary instrument of the SONARtrac flowmeter by connecting the piezoelectric film sensor to the SONARtrac flowmeter of CIDRA. "Signal quality" is displayed in the "Q area" of the secondary instrument of the SONARtrac flowmeter.

[0039] In the present invention, "normal temperature" is understood to be a temperature of 0 to 40°C.

[0040] In the present invention, the "mixed adhesive" is a mixture of a phenolic resin adhesive having a low viscosity, a solid content not exceeding 90%, and a long operability time and a polyisobutylene adhesive. Preferably, the phenolic resin adhesive is selected from phenolic resin VK-25, phenolic resin VK-50, or phenolic resin VK-3; preferably, the polyisobutylene adhesive is selected from PB1400, polyisobutylene PB1300, or polyisobutylene PB950.

[0041] In the present invention, the "adhesive" or "mixed adhesive" is stirred, poured onto a screen or coated onto the surface of a conductive metal strip, and then usually left to stand for a period of 1 minute to 2 hours.

[0042] In the present invention, the "protective film" is composed of a polymer material, for example, polyimide.

[0043] In the present invention, the "barrier tape" is composed of a polymer material, for example, one or more components of polyether, polyester or polyvinyl alcohol.

[0044] In the present invention, the "fastening belt", the "shielding net" and the "fixing rail" are respectively made of metal materials, for example, they can be respectively made of stainless steel.

[0045] Examples 1 to 15: Preparation of mixed adhesive

[0046] Take phenolic resin adhesive and polyisobutylene adhesive of different volume ratios, the total volume of the two is about 400mL; stir the two at room temperature for 25 to 35 minutes in advance, stir until they are uniform and have sufficient viscosity; pour the stirred phenolic resin adhesive into the polyisobutylene adhesive, and stir at room temperature for 1.5 to 2.5 hours, stir until they are uniform and have sufficient viscosity, to obtain a mixed adhesive, and let it stand for 15 to 25 minutes for use. Specifically, the model and volume ratio of the phenolic resin adhesive and the polyisobutylene adhesive in the mixed adhesive are shown in Table 1.

[0047] Table 1: Mixed adhesive preparation parameters

[0048]

[0049]

[0050] Examples 16-30: Preparation of piezoelectric film array sensors containing mixed adhesives

[0051] According to the parameters in Table 2, Figure 3 As shown, a piezoelectric film array sensor is prepared by screen printing, as follows:

[0052] S1: Prepare the stainless steel mold required for screen printing, which is 500 mm long, 500 mm wide and 165 μm thick. Cut 8 rectangular grooves in the mold, each of which is 453.1 mm long and 26.6 mm wide, and evenly distributed.

[0053] S2: Place a bottom plate (polyurethane pad) under the mold, and place a stainless steel metal conductive strip 11 that matches the size of the groove in each groove.

[0054] S3: Keep the ambient temperature at room temperature and the ambient humidity at 50-70%, place the screen flat on the mold so that the screen covers all the strips, pour the mixed adhesives obtained in Examples 1-15 respectively until the mixed adhesive covers the entire screen, and let it stand for 0.5-1.5 hours. After standing, use a scraper to evenly scrape the screen at a rate of 0.4-0.6 mm / s to evenly apply the mixed adhesive to the surface of the metal conductive strip 11 as an adhesive layer 12. After scraping, let it stand for 15-25 minutes. The process is as follows Figure 2 shown.

[0055] S4: Take out the strip 11 coated with the mixed adhesive, and paste the integrated piezoelectric film module (the piezoelectric film module consists of a piezoelectric film, an electrode, a protective layer 14 and a wire 13) on it to obtain a piezoelectric film strip 1, whose structure is as follows: Figure 4 shown.

[0056] S5: 8 piezoelectric film strips 1 are bonded to one side of the fastening belt 2 (stainless steel) through the adhesive layer 12, and the protective film 5 (polyimide) is bonded to the other side of the fastening belt 2. The fixed guide rails 21 are fixed to the two sides of the fastening belt 2 by welding, corresponding to the two ends of the piezoelectric film strips 1; a barrier belt 3 is arranged between the piezoelectric film strips 1, and the barrier belt 3 is also bonded to the fastening belt 2; and then the two sides of the shielding net 4 are welded and fixed to the fixed guide rails 21 on the two sides of the fastening belt 2 to obtain a piezoelectric film array sensor, whose structure is as follows: Figure 1 and Figure 2 shown.

[0057] Before the piezoelectric film array sensor is used to measure the flow rate of the liquid in the pipeline, it is necessary to curl the piezoelectric film array sensor, wrap it on the surface of the pipeline, and connect and fix the fixed rails 21 on both sides of the sensor through the fixing parts to complete the installation of the piezoelectric film array sensor; after the installation, the protective film 5 of the piezoelectric film array sensor is in direct contact with the outer wall of the pipeline, and the curled piezoelectric film strips 1 are perpendicular to the axis of the pipeline. When used specifically, the piezoelectric film array sensor also needs to be equipped with an external noise reduction and amplification circuit and a computer recording and analysis module.

[0058] Comparative Example 1: Preparation of piezoelectric film array sensor containing other adhesives

[0059] In this comparative example, except for using double-sided adhesive as the adhesive, the remaining steps and conditions for preparing the sensor are the same as those in Example 2 to obtain a sensor containing the corresponding adhesive. The parameters for preparing the sensor by screen printing are shown in Table 2.

[0060] Comparative Example 2: Preparation of piezoelectric film array sensor containing other adhesives

[0061] In this comparative example, except that polyurethane is used as the adhesive, the remaining steps and conditions for preparing the sensor are the same as those in Example 2 to obtain a sensor containing the corresponding adhesive. The parameters for preparing the sensor by screen printing are shown in Table 2.

[0062] Comparative Example 3: Preparation of piezoelectric film array sensor containing other adhesives

[0063] In this comparative example, except for using silicone grease as the adhesive, the remaining steps and conditions for preparing the sensor are the same as those in Example 2 to obtain a sensor containing the corresponding adhesive. The parameters for preparing the sensor by screen printing are shown in Table 2.

[0064] Table 2: Screen printing parameters

[0065]

[0066]

[0067] Test example:

[0068] Any piezoelectric film array sensor obtained in Examples 16-30 and Comparative Examples 1-3 is installed on the surface of a pipe with an outer diameter of 168 mm, and a water flow of a suitable flow rate is applied in the pipe to simulate a conventional usage scenario; the piezoelectric film array sensor is connected to the secondary instrument of CIDRA's SONARtrac flowmeter to test the signal quality of the sensor.

[0069] As shown in Table 3, sensors containing different adhesives were used to measure pipeline flow rates, and the signal quality of each sensor was read using the secondary instrument of the SONARtrac flowmeter. The signal quality of the sensors using double-sided adhesive, polyurethane, silicone grease and other common materials as adhesives in Comparative Examples 1-3 was basically between 0.3 and 0.5, while the signal quality of the sensors prepared using the mixed adhesives in Examples 16-30 could reach a maximum of 0.7 or above, which is comparable to the 0.8 signal quality level of the CIDRA VF-100 sensor, significantly improved by 80.65-145.16% compared to double-sided adhesive as an adhesive, and significantly improved by 19.15-61.70% compared to polyurethane as an adhesive.

[0070] Table 3: Sensor signal quality

[0071]

[0072] From the test results, it can be seen that the signal quality of the sensors in Examples 16-18 (corresponding to the mixed adhesive of phenolic resin VK-25 and polyisobutylene PB1400 in Examples 1-3) is better than that of other mixed adhesive combinations with the same mixing ratio. Referring to the methods of Examples 1 and 16, sensors using mixed adhesives of phenolic resin VK-25 and polyisobutylene PB1400 in ratios of 3:1 and 1:10 were further prepared and used to test the signal quality, which is integrated with the results in the test example as shown in Table 4 below; it can be seen that the mixed adhesive of phenolic resin VK-25 and polyisobutylene PB1400 in a volume ratio of 1:3 can obtain the relatively highest signal quality.

[0073] Table 4: Signal quality of mixed adhesives using phenolic resin VK-25 and polyisobutylene PB1400

[0074]

Claims

1. A mixed adhesive, characterized in that: The mixed adhesive consists of a phenolic resin adhesive and a polyisobutylene adhesive, and the volume ratio of the phenolic resin adhesive to the polyisobutylene adhesive is 1:1 to 1:

5.

2. The mixed adhesive according to claim 1, characterized in that The phenolic resin adhesive is selected from phenolic resin VK-25, phenolic resin VK-50 or phenolic resin VK-3; the polyisobutylene adhesive is selected from PB1400, polyisobutylene PB1300 or polyisobutylene PB950.

3. The mixed adhesive according to claim 1 or 2, characterized in that: The volume ratio of the phenolic resin adhesive to the polyisobutylene adhesive is 1:

3.

4. A method for preparing a mixed adhesive as claimed in any one of claims 1 to 3, characterized in that: The method comprises: taking a phenolic resin adhesive and a polyisobutylene adhesive in advance, stirring the two at room temperature for 20 to 40 minutes respectively, and standing for use; pouring the phenolic resin adhesive into the polyisobutylene adhesive, and stirring at room temperature for 1 to 3 hours to obtain a mixed adhesive.

5. A piezoelectric film strip array sensor, characterized in that: The piezoelectric film strip array sensor is composed of a piezoelectric film strip (1), a barrier strip (3), a fastening strip (2), a protective film (5) and a shielding net (4); wherein the piezoelectric film strip (1) is composed of a metal conductive strip (11), an adhesive layer (12), a wire (13) and a piezoelectric sheet, an electrode and a protective layer (14); fixed guide rails (21) are welded on two side edges of the fastening strip (2); the piezoelectric film strip (1) is bonded to one side of the fastening strip (2) through the adhesive layer (12), and the protective film (5) is bonded to the other side of the fastening strip (2); a barrier strip (3) is arranged between the piezoelectric film strips (1), and the barrier strip (3) is also bonded to the fastening strip (2); the two sides of the shielding net (4) are welded and fixed to the fixed guide rails 21 on the two side edges of the fastening strip (2); the adhesive layer (12) is composed of a mixed adhesive as described in any one of claims 1 to 3.

6. A method for preparing a piezoelectric film strip array sensor, characterized in that: The method comprises the following steps: S1: Prepare the stainless steel mold required for screen printing, cut and process rectangular grooves in the mold, and the grooves are evenly distributed at equal distances; S2: placing a metal conductive strip (11) in each groove; S3: Place the screen flat on the mold so that the screen covers all the metal conductive strips (11), pour the mixed adhesive until the mixed adhesive covers the entire screen, and let it stand; after the standing is completed, use a scraper to evenly scrape the screen to evenly apply the mixed adhesive to the surface of the metal conductive strips (11) as an adhesive layer (12); after scraping, let it stand; S4: taking out the strip coated with the mixed adhesive, and pasting the integrated piezoelectric film module on it to obtain a piezoelectric film strip (1); the piezoelectric film module is composed of a piezoelectric film, an electrode and a protective layer (14) and a wire (13); S5: The piezoelectric film strip is bonded to one side of the fastening belt (2) via an adhesive layer (12), and the protective film (5) is bonded to the other side of the fastening belt (2), wherein a fixed guide rail (21) is welded to the fastening belt (2); a barrier belt (3) is arranged between the piezoelectric film strips (1), and the barrier belt (3) is bonded to the fastening belt (2); and then the shielding net (4) and the fixed guide rail (21) are fixed by welding to obtain a piezoelectric film array sensor.

7. The method according to claim 6, characterized in that In step S3, the ambient temperature is 0-40° C. and the humidity is 50-70%.

8. The method according to claim 6, characterized in that In step S3, each standing time is independently 1 min to 2 h.

9. The method according to claim 6, characterized in that In step S3, the scraper evenly scrapes the screen at a rate of 0.1-1 mm / s.

10. A method for testing pipeline flow rate, characterized in that: The method comprises using the hybrid adhesive according to any one of claims 1 to 4 or the piezoelectric film strip array sensor according to claim 5 .

11. Use of the mixed adhesive according to any one of claims 1 to 3 or the piezoelectric film strip array sensor according to claim 5 in pipeline flow velocity measurement.

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