A method for improving PO substrate adhesion

Abstract

The present invention relates to the technical field of tape preparation, and in particular to a method for improving the adhesion of a PO substrate. The method comprises forming a primer; applying and controlling the speed of a coating roller; periodically monitoring the coating process; and drying the PO film. The present invention periodically monitors the coating process to analyze the uniformity of the transverse coating thickness, and continuously measures the actual thickness after coating as the pressure roller rotates to analyze the uniformity of the longitudinal coating thickness, that is, by drawing a thickness fluctuation curve, analyzing the change trend of the thickness fluctuation curve, and analyzing whether there is obvious fluctuation or abnormality in the thickness fluctuation curve. If so, timely intervene in the coating process to maintain the stability of the coating process, dry the coating by using an oven, and avoid contacting the guide roller with too large an angle when the PO film just comes out of the oven, so as to prevent the PO film from wrinkling due to increased surface viscosity after heating, thereby ensuring the quality of the PO film.

Description

Technical Field

[0001] The invention relates to the technical field of adhesive tape preparation, and in particular to a method for improving the adhesion of a PO substrate. Background Art

[0002] In the tape production process, when PO film (polyolefin film) is used as the substrate for coating glue, if the PO film is not surface treated, the adhesion ability is poor and the produced tape is prone to debonding during use. Therefore, PO film manufacturers often perform corona treatment before shipment. PO film manufacturers generally use air corona. The essence of air corona is to use the plasma generated after ionizing the air to bombard the film surface to form oxides on the surface. This method increases the surface dyne of the PO film while also increasing the surface polarity of PO. However, for some glue formulas with lower polarity or special ingredients, corona will not only not improve adhesion but sometimes even have the opposite effect. Therefore, a new method to improve the adhesion of PO film is urgently needed.

[0003] The Chinese patent document with publication number CN117417703A discloses a BOPP tape with ultra-high viscosity and high heat resistance, a preparation method and a preparation system, including: substrate: BOPP film: 100% (by weight); UV isolation layer: metal oxide coating, coated on the substrate layer; adhesive formula range: high viscosity resin: acrylic resin: 40-45%, natural rubber: 8-10%, synthetic rubber: 4-5%; UV curing system: UV curing monomer: 1.5-2.5%, photoinitiator: 0.4-0.7%; thermal stabilizer: organic tin compound: 2.5-3.5%; adhesion promoter: isocyanate: 5-7% filler: powdered zinc oxide or calcium carbonate: 4-6% antioxidant: Hindered phenol antioxidant: 0.8-1.2%; solvent: organic solvent: 23-27%; It can be seen that in the existing tape production process, there is a lack of real-time monitoring of thickness changes or wrap angles during the coating process and after the PO substrate leaves the oven to flexibly adjust the coating parameters, resulting in uneven film coating on the surface of the PO substrate, resulting in low film quality. Summary of the invention

[0004] To this end, the present invention provides a method for improving the adhesion of PO substrates to overcome the problem in the prior art that the formed film is uneven and the quality of the film is low due to the lack of real-time monitoring of the PO film during the coating process and after leaving the oven.

[0005] To achieve the above object, the present invention provides a method for improving the adhesion of a PO substrate, comprising:

[0006] The polymer solution is diluted with a solvent to a solid content of less than 10% to form a primer solution;

[0007] Wherein, the solvent is isopropanol, and the polymer solution is polyvinyl alcohol or polyacrylic acid;

[0008] The primer coating liquid is applied to the coating machine so that the primer coating liquid is applied to the surface of the PO substrate to form a PO film, and in the process of applying the primer coating liquid to the coating machine, the actual coating thickness of the PO film is obtained in real time, and the speed of the coating roller is controlled based on the actual coating thickness, wherein the speed control process is to adjust the initial coating speed of the coating roller according to the actual coating thickness, and adjust the actual coating thickness to be greater than or equal to the standard coating thickness;

[0009] Periodically monitor the coating process to analyze whether the coating thickness is qualified;

[0010] Among them, the periodic monitoring of the coating process includes collecting the coating thickness data at each sampling point in each detection area at a preset time interval, generating the coating thickness imaging of the corresponding detection area according to the coating thickness data, and judging the uniformity of the transverse coating thickness based on the coating thickness imaging of the current cycle, and when judging that the transverse coating thickness is uneven, obtaining the adjacent coating thickness of the adjacent detection area corresponding to the next cycle as the pressure roller rotates, drawing a thickness fluctuation curve, analyzing the change trend of the thickness fluctuation curve, so as to analyze the uniformity of the longitudinal coating thickness; the qualified coating thickness includes uniform transverse coating thickness and uniform longitudinal coating thickness;

[0011] The PO film with qualified coating thickness is moved to the oven for drying and removed, and the removed PO film is tested for on-machine wrap angle to determine whether the preset winding tension should be adjusted;

[0012] The PO film after exiting the oven is rolled up to complete the coating process of the PO film and obtain an improved PO film.

[0013] Further, adjusting the initial coating speed of the coating roller according to the actual coating thickness includes:

[0014] Compare the standard coating thickness with the actual coating thickness to obtain a comparison result;

[0015] When the actual coating thickness is less than the standard coating thickness, the initial coating speed is increased to the first coating speed, and the control process of the initial coating speed of the coating roller is analyzed to determine whether the speed control process is normal according to the analysis result.

[0016] Further, judging the uniformity of the lateral coating thickness based on the coating thickness imaging of the current cycle includes:

[0017] The maximum coating thickness difference in the coating thickness imaging is obtained, and the maximum coating thickness difference is judged according to the standard coating thickness difference to determine whether the coating thickness of the current detection area corresponding to the current cycle is uniform, and then determine whether the lateral coating thickness is uniform.

[0018] Further, determining the maximum coating thickness difference according to the standard coating thickness difference includes:

[0019] If the maximum coating thickness difference is less than or equal to the standard coating thickness difference, it is determined that the transverse coating thickness is uniform, and the maximum coating thickness difference of the next preset collection cycle is continuously obtained for determination;

[0020] If the maximum coating thickness difference is greater than the standard coating thickness difference, it is determined that the transverse coating thickness is uneven, and the preset winding tension is increased to the first corrected winding tension.

[0021] Further, the analysis of the uniformity of the longitudinal coating thickness includes,

[0022] When determining that the transverse coating thickness is uneven, the actual coating thickness of the current detection area is obtained to obtain the current detection thickness, and the result of the coating thickness detection in the next acquisition cycle is obtained to obtain the adjacent detection thickness corresponding to the adjacent detection area;

[0023] Calculate the difference between the adjacent detection thickness and the current detection thickness to obtain the detection thickness deviation value, compare the allowed detection thickness deviation value with the detection thickness deviation value, and determine whether to draw a thickness fluctuation curve based on the comparison result;

[0024] The adjacent detection thickness is the average value of the coating thickness corresponding to each sampling point in the thickness imaging corresponding to the adjacent detection area.

[0025] Further, determining whether to draw a thickness fluctuation curve according to the comparison result includes:

[0026] When the detected thickness deviation value is less than or equal to the allowed detected thickness deviation value, the coating thickness is judged to be qualified;

[0027] When the detected thickness deviation value is greater than the allowable detected thickness deviation value, a curve of the detected thickness deviation value changing with time is plotted to obtain a thickness fluctuation curve;

[0028] The thickness deviation value and the corresponding time of each acquisition cycle are obtained as each detection point, and the detection points are connected to obtain the thickness fluctuation curve.

[0029] Further, analyzing the variation trend of the thickness fluctuation curve includes:

[0030] Obtain the slope between two adjacent detection points in the thickness fluctuation curve to obtain the thickness fluctuation change rate;

[0031] The thickness fluctuation change rate of each preset acquisition period is obtained, a thickness fluctuation change rate versus time curve is plotted, and the slope of the change curve is analyzed to analyze whether the longitudinal coating thickness is uniform.

[0032] Further, analyzing the slope of the variation curve to analyze whether the longitudinal coating thickness is uniform includes:

[0033] If the slope of the change curve is less than or equal to the standard fluctuation change rate, it is determined that the longitudinal coating thickness is uniform;

[0034] If the slope of the change curve is greater than the standard fluctuation change rate, it is determined that the longitudinal coating thickness is uneven, and the preset storage temperature in the glue box is reduced to the corrected storage temperature.

[0035] Furthermore, the removed PO film is subjected to an on-machine wrap angle test including:

[0036] Obtaining a measurement result according to the distance data obtained by the laser rangefinder;

[0037] The measurement results are fed back to the control system in real time, and the preset winding tension is adjusted down to the second corrected winding tension according to the change of the actual wrap angle.

[0038] Further, the regulation process of the initial coating speed of the coating roller is analyzed including:

[0039] Plotting a coating thickness versus coating speed curve to obtain a thickness variation curve, and analyzing a variation trend of the thickness variation curve to determine whether to modify a preset maximum coating speed according to the analysis result;

[0040] The maximum coating thickness corresponding to the peak point of the thickness variation curve is obtained, and the maximum coating thickness is determined according to the standard coating thickness to analyze whether the speed control process of the coating process is normal.

[0041] Compared with the prior art, the beneficial effect of the present invention is that, since most PO will soften and shrink at around 80°C, and may even be severely deformed due to the influence of coating tension, the polymer film pre-coating method under low temperature conditions is combined to improve the adhesion of the polyolefin (PO) surface, and the polymer solution is diluted with a low-boiling point solvent to a solid content of <10%, and then the coating machine is applied to the PO coating surface, and the solvent is dried in an oven to control the dry thickness of the coating to be less than 1um, and the coating process is periodically monitored, that is, the actual thickness after coating is measured by a vertical electronic thickness gauge to analyze the uniformity of the transverse coating thickness, and the actual thickness after coating is continuously measured as the pressure roller rotates to analyze the longitudinal coating thickness. The uniformity of the thickness of the cloth, that is, by drawing a thickness fluctuation curve, analyzing the changing trend of the thickness fluctuation curve, and analyzing whether there is obvious fluctuation or abnormality in the thickness fluctuation curve. If so, it indicates that there is a problem in the coating process, such as excessive temperature causing the PO material to soften or deform. In this case, timely intervention is made in the coating process to maintain the stability of the coating process. The coating is dried in an oven. During the drying process, the drying state of the coating is regularly checked to ensure that the coating is completely dry and free of bubbles or defects. When the PO film just comes out of the oven, avoid contact with the guide roller with too large an angle, or perform anti-sticking treatment on the surface of the guide roller to prevent the PO film from wrinkling due to increased surface viscosity after heating, thereby ensuring the quality of the formed PO film. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic flow chart of a method for improving PO substrate adhesion according to an embodiment of the present invention;

[0043] Figure 2 This is a schematic diagram of the structure of the PO substrate after glue coating according to an embodiment of the present invention;

[0044] Figure 3 This is a schematic diagram of the structure of the PO substrate after surface treatment according to an embodiment of the present invention;

[0045] Figure 4 This is a schematic diagram of mutual tearing verification according to an embodiment of the present invention. DETAILED DESCRIPTION

[0046] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0047] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the protection scope of the present invention.

[0048] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside" and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the drawings. This is merely for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0049] In addition, it should be noted that in the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0050] See also Figure 1 As shown, it is a schematic flow diagram of a method for improving PO substrate adhesion according to an embodiment of the present invention. The present invention provides a method for improving PO substrate adhesion, comprising:

[0051] Step S1, diluting the polymer solution with a low boiling point solvent to a solid content of less than 10% to form a primer solution;

[0052] Wherein, the low boiling point solvent is isopropanol, and the polymer solution is polyvinyl alcohol or polyacrylic acid;

[0053] Step S2, applying the primer on the machine so that the primer is applied on the surface of the PO substrate to form a PO film, and in the process of applying the primer on the machine, obtaining the actual coating thickness of the PO film in real time, and adjusting the speed of the coating roller based on the actual coating thickness, wherein the speed control process is to adjust the initial coating speed of the coating roller according to the actual coating thickness, and adjust the actual coating thickness to be greater than or equal to the standard coating thickness;

[0054] Step S3, periodically monitoring the coating process with a preset collection period to analyze whether the coating thickness is qualified;

[0055] Among them, the periodic monitoring of the coating process includes collecting the coating thickness data at each sampling point in each detection area at a preset time interval, generating the coating thickness imaging of the corresponding detection area according to the coating thickness data, and judging the uniformity of the transverse coating thickness based on the coating thickness imaging of the current cycle, and when judging that the transverse coating thickness is uneven, obtaining the adjacent coating thickness of the adjacent detection area corresponding to the next cycle as the pressure roller rotates, drawing a thickness fluctuation curve, analyzing the change trend of the thickness fluctuation curve, so as to analyze the uniformity of the longitudinal coating thickness; the qualified coating thickness includes uniform transverse coating thickness and uniform longitudinal coating thickness;

[0056] Step S4, moving the PO film with qualified coating thickness to an oven for drying and removing it, and performing an on-machine wrap angle test on the removed PO film to determine whether to adjust the preset winding tension;

[0057] The PO film after exiting the oven is rolled up to complete the coating process of the PO film and obtain an improved PO film.

[0058] In step S4 of the present embodiment, a stepped temperature is set, and the highest temperature is controlled between 60°C and 80°C. The temperature is gradually increased to avoid deformation of the PO material due to a sudden temperature rise. The solid content is the ratio of the mass of the solid matter in the mixed solution of the low boiling point solvent and the polymer solution to the total mass.

[0059] In this embodiment, the primer liquid is attached to the surface of the PO substrate by a micro-concave coating method, and the primer liquid is added to the glue box system to uniformly supply the primer liquid to the surface of the coating roller, and the coating roller is rotated at the initial coating speed to uniformly apply the primer liquid to the PO substrate; the tiny grooves on the surface of the coating roller can accurately control the thickness of the primer liquid, and when the coating roller rotates, the primer liquid is squeezed into the grooves, and the PO substrate passes through the coating roller at a preset winding tension and a preset winding speed, so that the primer liquid squeezed into the grooves is evenly coated on the surface of the PO substrate to form a film. The coating roller is a cylinder made of metal or ceramic, with a precisely designed tiny groove on the surface. The shape of the groove can be V-shaped or circular, which is not specifically limited here, depending on the desired coating pattern and the characteristics of the primer liquid. The depth of the groove preliminarily determines the thickness of the coating adhesive. In this embodiment, the groove depth is 2um, the preset winding speed is 20 m / min, and the vertical electronic thickness gauge is installed 5cm below the coating roller to achieve real-time detection of the coating thickness.

[0060] Since most PO will soften and shrink around 80℃, and may even be severely deformed due to the coating tension, the high molecular film pre-coating method under low temperature conditions is combined to improve the adhesion of the polyolefin (PO) surface. The high molecular solution is diluted with a low boiling point solvent to a solid content of <10%, and then the coating machine is applied to the PO coating surface. The solvent is dried in an oven to control the dry coating thickness below 1um. The coating process is periodically monitored, that is, the actual thickness after coating is measured by a vertical electronic thickness gauge to analyze the uniformity of the transverse coating thickness. The actual thickness after coating is continuously measured as the pressure roller rotates to analyze the uniformity of the longitudinal coating thickness, that is, the thickness fluctuation curve is drawn to analyze the thickness uniformity. Analyze the changing trend of the thickness fluctuation curve, and analyze whether there is obvious fluctuation or abnormality in the thickness fluctuation curve. If so, it indicates that the temperature is too high during the coating process, causing the PO material to soften or deform. In this case, intervene in the coating process in time to maintain the stability of the coating process. Dry the coating in an oven. During the drying process, check the drying state of the coating regularly to ensure that the coating is completely dry and free of bubbles or defects. When the PO film just comes out of the oven, avoid contact with the guide roller at a large wrap angle, or perform anti-sticking treatment on the surface of the guide roller to prevent the PO film from wrinkling due to increased surface viscosity after heating, so as to ensure the quality of the formed PO film; anti-sticking treatment is to roughen the surface of the guide roller microscopically by mechanical engraving or chemical etching.

[0061] Specifically, in step S2, adjusting the initial coating speed of the coating roller according to the actual coating thickness includes:

[0062] Compare the standard coating thickness with the actual coating thickness to obtain a comparison result;

[0063] When the actual coating thickness is less than the standard coating thickness, the initial coating speed is increased to the first coating speed, and the control process of the initial coating speed of the coating roller is analyzed to determine whether the speed control process is normal according to the analysis result;

[0064] When the actual coating thickness is greater than or equal to the standard coating thickness, the coating process is periodically monitored.

[0065] Wherein, Vc1=min{Vc×[1+(Xb-Xs) / Xb], Vmax}, Vc is the initial coating speed, Vc1 is the first coating speed, Xb is the standard coating thickness, Xs is the actual coating thickness, and Vmax is the preset maximum coating speed of the coating roller;

[0066] In this embodiment, the standard coating thickness is set to 1um. Since the coating thickness increases with the increase of the speed of the coating roller, the coating thickness is increased accordingly. The coating speed is gradually increased to increase the coating thickness accordingly, that is, the speed of the coating roller is increased to the first coating speed to achieve adaptive increase in the speed of the coating roller and improve the intelligence of the equipment. However, when the speed of the coating roller increases to a certain fixed value, the coating thickness reaches a maximum value. At this time, as the speed of the coating roller continues to increase, the coating thickness slowly decreases. Therefore, the fixed value is set as the preset maximum coating speed, and during the coating process, the coating effect is monitored to analyze whether to adjust the preset maximum coating speed, so as to adaptively optimize and adjust the set parameters to ensure the coating effect.

[0067] Specifically, in step S2, the regulation process of the initial coating speed of the coating roller is analyzed, including:

[0068] Plotting a coating thickness versus coating speed curve to obtain a thickness variation curve, and analyzing a variation trend of the thickness variation curve to determine whether to modify a preset maximum coating speed according to the analysis result;

[0069] The maximum coating thickness corresponding to the peak point of the thickness variation curve is obtained, and the maximum coating thickness is determined according to the standard coating thickness to analyze whether the speed control process of the coating process is normal.

[0070] Specifically, analyzing the variation trend of the thickness variation curve includes:

[0071] If the thickness variation curve has a peak, obtain the coating speed corresponding to the peak point, obtain the corrected maximum coating speed, and correct the preset maximum coating speed to the corrected maximum coating speed;

[0072] If there is no peak in the thickness variation curve, no correction is made to the preset maximum coating speed.

[0073] Specifically, analyzing whether the speed control process of the coating process is normal includes:

[0074] When the maximum coating thickness is less than the standard coating thickness, the speed control process is judged to be abnormal and on-site inspection and processing are carried out;

[0075] When the maximum coating thickness is greater than or equal to the standard coating thickness, it is determined that the speed control process is normal.

[0076] In this embodiment, the preset maximum coating speed is set to 20 meters per minute. Through real-time analysis of the coating thickness during the speed control process, when the coating thickness reaches the peak value, if it still does not reach the standard coating thickness, it means that the equipment is abnormal and staff are required to go to the site for inspection to improve the timeliness of the early warning.

[0077] Specifically, in step S3, judging the uniformity of the lateral coating thickness based on the coating thickness imaging of the current cycle includes:

[0078] The maximum coating thickness difference in the coating thickness imaging is obtained, and the maximum coating thickness difference is judged according to the standard coating thickness difference to determine whether the coating thickness in the current detection area is uniform, and further determine whether the lateral coating thickness is uniform.

[0079] Specifically, judging the maximum coating thickness difference according to the standard coating thickness difference includes:

[0080] If the maximum coating thickness difference is less than or equal to the standard coating thickness difference, it is determined that the transverse coating thickness is uniform, and the maximum coating thickness difference of the next preset collection cycle is continuously obtained for determination;

[0081] If the maximum coating thickness difference is greater than the standard coating thickness difference, it is determined that the transverse coating thickness is uneven, and the preset winding tension is increased to the first corrected winding tension;

[0082] Wherein, Fc1'=min{Fc×[1+(ΔFs-ΔFb) / ΔFs], Fmax}, Fc1' is the first modified winding tension, Fc is the preset winding tension, Fmax is the maximum winding tension, ΔFs is the maximum coating thickness difference, and ΔFb is the standard coating thickness difference;

[0083] The preset winding tension set in this embodiment is 2.5 kgf / cm, and the maximum winding tension is 3.0 kgf / cm.

[0084] By determining that the transverse coating thickness is uneven, the winding tension is adaptively increased to ensure the flatness of the PO film, thereby improving the uniformity of the coating.

[0085] Specifically, obtaining the maximum coating thickness difference in the coating thickness imaging includes:

[0086] The coating thickness imaging is divided into several simulated coating modules by vertical lines, and the average coating thickness of each simulated coating module is calculated and recorded as the simulated coating thickness. The simulated coating thicknesses are added and divided by the number of simulated coating modules to obtain the actual coating thickness of the current detection area. The actual coating thickness is subtracted from each simulated coating thickness to obtain several coating thickness differences. The absolute value of each coating thickness difference is taken, and the maximum value among the absolute values ​​is obtained as the maximum coating thickness difference.

[0087] By obtaining the actual measured thickness corresponding to each sampling point in the current detection area, the uniformity of the coating thickness in the current detection area is analyzed. The calculation is simple and effective. The coating thickness imaging is divided into several simulated coating modules, that is, the coating thickness simulation is divided into blocks, and the average thickness of each area is calculated as the simulated coating thickness of each simulated coating unit. The average value of each simulated coating thickness is calculated as the actual coating thickness. By comparing the actual coating thickness with the simulated coating thickness, the thickness deviation value is calculated, and the largest thickness difference is selected as the maximum thickness deviation value to ensure accurate calculation.

[0088] Specifically, in step S3, analyzing the uniformity of the longitudinal coating thickness includes:

[0089] When determining that the transverse coating thickness is uneven, the actual coating thickness of the current detection area is obtained to obtain the current detection thickness, and the result of the coating thickness detection in the next acquisition cycle is obtained to obtain the adjacent detection thickness corresponding to the adjacent detection area;

[0090] Calculate the difference between the adjacent detection thickness and the current detection thickness to obtain the detection thickness deviation value, compare the allowed detection thickness deviation value with the detection thickness deviation value, and determine whether to draw a thickness fluctuation curve based on the comparison result;

[0091] Wherein, the adjacent detection thickness is the average value of the coating thickness corresponding to each sampling point in the thickness imaging corresponding to the adjacent detection area;

[0092] The preset time interval in this embodiment is the time corresponding to the endpoint of the preset sampling period. The preset sampling period is determined based on experiments and is determined based on the actual speed of the coating roller and the length of the detection area collected by the imaging device. That is, the length of the detection area along the moving direction of the substrate is obtained, and the quotient of the actual speed of the coating roller and this length is calculated to obtain the preset time interval. The preset time interval is a time length, which characterizes the actual detection frequency. For example, if the coating speed is 1 m / s and the length of the detection area along the moving direction of the substrate is 0.1 m, then the preset sampling period should be 0.1 seconds.

[0093] Specifically, determining whether to draw a thickness fluctuation curve according to the comparison result includes:

[0094] When the detected thickness deviation value is less than or equal to the allowed detected thickness deviation value, the coating thickness is judged to be qualified;

[0095] When the detected thickness deviation value is greater than the allowable detected thickness deviation value, a curve of the detected thickness deviation value changing with time is plotted to obtain a thickness fluctuation curve;

[0096] The thickness deviation value and the corresponding time of each acquisition cycle are obtained as each detection point, and the detection points are connected to obtain the thickness fluctuation curve.

[0097] The allowable detection thickness deviation value set in this embodiment allows the thickness difference value of the PO substrate surface to fluctuate in the longitudinal direction. Generally, it is set between 0.05um-0.1um and is selected according to the actual coating process requirements.

[0098] Specifically, analyzing the variation trend of the thickness fluctuation curve includes:

[0099] Obtain the slope between two adjacent detection points in the thickness fluctuation curve to obtain the thickness fluctuation change rate;

[0100] The thickness fluctuation change rate of each preset acquisition period is obtained, a thickness fluctuation change rate versus time curve is plotted, and the slope of the change curve is analyzed to analyze whether the longitudinal coating thickness is uniform.

[0101] Specifically, analyzing the slope of the variation curve to analyze whether the longitudinal coating thickness is uniform includes:

[0102] If the slope of the change curve is less than or equal to the standard fluctuation change rate, it is determined that the longitudinal coating thickness is uniform;

[0103] If the slope of the change curve is greater than the standard fluctuation change rate, it is determined that the longitudinal coating thickness is uneven, and the preset storage temperature in the glue box is reduced to the corrected storage temperature;

[0104] Wherein, Tc'=Tc×[1-(Ks-Kb) / Ks], Tc is the preset storage temperature, Tc' is the corrected storage temperature, Kb is the standard fluctuation change rate, and Ks is the slope of the change curve.

[0105] The preset storage temperature set in this embodiment is 25°C, and the set standard fluctuation change rate represents the threshold value of the uniformity and stability of the longitudinal coating thickness of the coating. During the monitoring process, if the calculated curve change rate exceeds this standard value, it is determined that the longitudinal thickness of the coating is uneven. In this case, it means that both the lateral displacement and the longitudinal displacement are abnormal, indicating that the temperature affects the fluidity of the glue solution. It is necessary to adjust the temperature in the glue box in time to improve the coating process.

[0106] Specifically, in step S4, the on-machine wrap angle test of the removed PO film includes:

[0107] Fix the laser rangefinder and angle sensor near the guide roller. The specific installation position is not limited. It only needs to ensure that the contact angle between the PO film and the guide roller is fully detected.

[0108] The laser beam is emitted by a laser distance meter to measure the distance from the surface of the PO film to the surface of the guide roller;

[0109] According to the distance data obtained by the laser rangefinder and the geometric shape of the film, the wrap angle is calculated using trigonometric functions. The specific formula is: θs=arctan( ), is the height difference between the PO film and the guide roller, is the horizontal distance between the PO film and the guide roller, θs is the actual wrap angle;

[0110] Feedback the measurement results to the control system in real time, and automatically adjust the coating parameters (preset winding tension) according to the actual wrap angle changes to ensure the quality of the film;

[0111] Compare the standard wrap angle with the actual wrap angle.

[0112] If the actual wrap angle is less than or equal to the standard wrap angle, the winding tension will not be adjusted;

[0113] If the actual wrap angle is greater than the standard wrap angle, the preset winding tension is reduced to the second corrected winding tension;

[0114] Among them, Fc2'=max{Fc×[1-(θs-θb) / θs], Fmin}, Fc2' is the second modified winding tension, Fc is the preset winding tension, Fmin is the minimum winding tension, θs is the actual wrap angle, and θb is the standard wrap angle.

[0115] In this embodiment, the standard wrap angle is 15° and the minimum winding tension is 1.5 kgf / cm.

[0116] When the film just comes out of the oven, due to its high surface temperature and increased viscosity, the winding tension is adaptively adjusted to a smaller value according to the actual wrap angle to reduce the contact pressure between the film and the guide roller, reduce the risk of adhesion, and avoid wrinkles in the PO film.

[0117] Specifically, in Example 1, the coating adhesion test, the adhesion between the coating and the PO surface was evaluated using a standard adhesion test method (mutual tearing to verify adhesion);

[0118] The test calculates the surface energy dispersion part and polar part according to the WORK method to evaluate the adhesion improvement effect. The dyne test cannot reflect the surface energy dispersion component and polar component.

[0119] Mutual tearing to verify adhesion: Apply the same high-viscosity glue (the experiment uses low-polarity glue) on the treated PO surface, stick two pairs of tapes together, and then quickly separate the two tapes. The glue on the substrate with poor adhesion will transfer to the substrate with good adhesion, so as to judge the adhesion performance of different treatment methods. O: Good, : Average, X: Poor.

[0120] See also Figure 2 , Figure 3 as well as Figure 4 As shown, Figure 2 This is a schematic diagram of the structure of the PO substrate after glue coating according to an embodiment of the present invention. Figure 3 This is a schematic diagram of the structure of the PO substrate after surface treatment according to an embodiment of the present invention. Figure 4 Table 1 is a schematic diagram of mutual tearing verification of the embodiment of the present invention. Table 1 is the coating adhesion test index and results. Figure 2 , Figure 3 , Figure 4 As can be seen from Table 1, the coating method of this embodiment has a good adhesion improvement effect compared with no surface treatment, corona treatment or heat treatment of the PO substrate, that is, the adhesion between the improved PO film prepared by the attachment method of this embodiment and the glue is increased.

[0121] Table 1

[0122] The improved PO film prepared in this embodiment achieves the effect of increasing the bonding strength by promoting the crosslinking of the main chain tertiary carbon atoms of the elastomer and polyethylene blend in the PO film and the glue, and provides experimental data that can confirm that the above-mentioned substrate formula can increase the bonding strength between the PO film and the glue, while providing control experiments of other treatment methods.

[0123] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

[0124] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for improving the adhesion of a PO substrate, characterized in that: include, The polymer solution is diluted with a solvent to a solid content of less than 10% to form a primer solution; Wherein, the solvent is isopropanol, and the polymer solution is polyvinyl alcohol or polyacrylic acid; The primer coating liquid is applied to the coating machine so that the primer coating liquid is applied to the surface of the PO substrate to form a PO film, and in the process of applying the primer coating liquid to the coating machine, the actual coating thickness of the PO film is obtained in real time, and the speed of the coating roller is controlled based on the actual coating thickness, wherein the speed control process is to adjust the initial coating speed of the coating roller according to the actual coating thickness, and adjust the actual coating thickness to be greater than or equal to the standard coating thickness; Adjusting the initial coating speed of the coating roller according to the actual coating thickness includes: Compare the standard coating thickness with the actual coating thickness to obtain a comparison result; When the actual coating thickness is less than the standard coating thickness, the initial coating speed is increased to the first coating speed, and the control process of the initial coating speed of the coating roller is analyzed to determine whether the speed control process is normal according to the analysis result; Periodically monitor the coating process to analyze whether the coating thickness is qualified; Wherein, the periodic monitoring of the coating process includes collecting the coating thickness data at each sampling point in each detection area at a preset time interval, generating the coating thickness imaging of the corresponding detection area according to the coating thickness data, and judging the uniformity of the transverse coating thickness based on the coating thickness imaging of the current cycle, and when judging that the transverse coating thickness is uneven, obtaining the adjacent coating thickness of the adjacent detection area corresponding to the next cycle as the pressure roller rotates, drawing a thickness fluctuation curve, and analyzing the change trend of the thickness fluctuation curve to analyze the uniformity of the longitudinal coating thickness; The qualified coating thickness includes uniform coating thickness in the transverse direction and uniform coating thickness in the longitudinal direction; The PO film with qualified coating thickness is moved to the oven for drying and removed, and the removed PO film is tested for on-machine wrap angle to determine whether the preset winding tension should be adjusted; The PO film after exiting the oven is rolled up to complete the coating process of the PO film and obtain an improved PO film.

2. The method for improving PO substrate adhesion according to claim 1, characterized in that: The uniformity of the lateral coating thickness is determined based on the coating thickness imaging of the current cycle, including: The maximum coating thickness difference in the coating thickness imaging is obtained, and the maximum coating thickness difference is judged according to the standard coating thickness difference to determine whether the coating thickness of the current detection area corresponding to the current cycle is uniform, and then determine whether the lateral coating thickness is uniform.

3. The method for improving PO substrate adhesion according to claim 2, characterized in that: The maximum coating thickness difference is determined based on the standard coating thickness difference, including: If the maximum coating thickness difference is less than or equal to the standard coating thickness difference, it is determined that the transverse coating thickness is uniform, and the maximum coating thickness difference of the next preset collection cycle is continuously obtained for determination; If the maximum coating thickness difference is greater than the standard coating thickness difference, it is determined that the transverse coating thickness is uneven, and the preset winding tension is increased to the first corrected winding tension.

4. The method for improving PO substrate adhesion according to claim 3, characterized in that: Analysis of longitudinal coating thickness uniformity includes, When determining that the transverse coating thickness is uneven, the actual coating thickness of the current detection area is obtained to obtain the current detection thickness, and the result of the coating thickness detection in the next preset acquisition cycle is obtained to obtain the adjacent detection thickness corresponding to the adjacent detection area; Calculate the difference between the adjacent detection thickness and the current detection thickness to obtain the detection thickness deviation value, compare the allowed detection thickness deviation value with the detection thickness deviation value, and determine whether to draw a thickness fluctuation curve based on the comparison result; The adjacent detection thickness is the average value of the coating thickness corresponding to each sampling point in the thickness imaging corresponding to the adjacent detection area.

5. The method for improving PO substrate adhesion according to claim 4, characterized in that: Determine whether to draw the thickness fluctuation curve based on the comparison results, including: When the detected thickness deviation value is less than or equal to the allowed detected thickness deviation value, the coating thickness is judged to be qualified; When the detected thickness deviation value is greater than the allowable detected thickness deviation value, a curve of the detected thickness deviation value changing with time is plotted to obtain a thickness fluctuation curve; The thickness deviation value and the corresponding time of each acquisition cycle are obtained as each detection point, and the detection points are connected to obtain the thickness fluctuation curve.

6. The method for improving PO substrate adhesion according to claim 5, characterized in that: Analyzing the variation trend of the thickness fluctuation curve includes: Obtain the slope between two adjacent detection points in the thickness fluctuation curve to obtain the thickness fluctuation change rate; The thickness fluctuation change rate of each preset acquisition period is obtained, a thickness fluctuation change rate versus time curve is plotted, and the slope of the change curve is analyzed to analyze whether the longitudinal coating thickness is uniform.

7. The method for improving PO substrate adhesion according to claim 6, characterized in that: Analyzing the slope of the variation curve to analyze whether the longitudinal coating thickness is uniform includes: If the slope of the change curve is less than or equal to the standard fluctuation change rate, it is determined that the longitudinal coating thickness is uniform; If the slope of the change curve is greater than the standard fluctuation change rate, it is determined that the longitudinal coating thickness is uneven, and the preset storage temperature in the glue box is reduced to the corrected storage temperature.

8. The method for improving PO substrate adhesion according to claim 1, characterized in that: The on-machine wrap angle test of the removed PO substrate includes: Obtaining a measurement result according to the distance data obtained by the laser rangefinder; The measurement results are fed back to the control system in real time, and the preset winding tension is adjusted down to the second corrected winding tension according to the change of the actual wrap angle.

9. The method for improving PO substrate adhesion according to claim 1, characterized in that: The analysis of the control process of the initial coating speed of the coating roller includes: Plotting a coating thickness versus coating speed curve to obtain a thickness variation curve, and analyzing a variation trend of the thickness variation curve to determine whether to modify a preset maximum coating speed according to the analysis result; The maximum coating thickness corresponding to the peak point of the thickness variation curve is obtained, and the maximum coating thickness is determined according to the standard coating thickness to analyze whether the speed control process of the coating process is normal.

Images