Apparatus and method for producing high barrier mdope films

Abstract

The application relates to the technical field of film preparation, in particular to a preparation equipment and method of high-barrier MDOPE film, which comprises a stretching module, a film thickness tester and a central control processor, the central control processor sets the operation parameters of the stretching module according to the detection result of the film thickness tester, the central control processor comprises a parameter determination unit, a first control unit and a second control unit which are connected with each other, the parameter determination unit determines the preset stretching length and the preset stretching width of the film, and determines the starting stretching speed and the speed gradient of the stretching roller group based on the preset stretching length and the preset stretching width; the first control unit calculates the stretching adjustment parameters when the uniformity of the film does not meet the standard, and controls the stretching speed of the stretching roller in the stretching roller group based on the stretching adjustment parameters; the second control unit calculates the stretching speed ratio of the actual starting stretching speed and the starting transverse stretching speed to determine the stretching orientation of the film after the longitudinal stretching is completed. The application improves the uniformity of the film.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of thin film preparation, in particular to a high-barrier MDOPE film preparation equipment and method. BACKGROUND

[0002] The basic principle of the biaxial stretching technology is that the high polymer raw material is heated and melted by an extruder to form a thick sheet, and then stretched in the longitudinal and transverse directions by a longitudinal stretching machine and a transverse stretching machine at a suitable temperature range above the glass transition temperature and below the melting point (in the high elastic state), so that the molecular chains or crystal faces are oriented and arranged in the direction parallel to the film plane under the action of external force, and then heat set in the stretched state to fix the oriented macromolecular structure, and then coated with a high molecular conductive liquid / permanent antistatic agent, and finally cooled and processed to obtain a permanent antistatic transparent film.

[0003] The common features of biaxially stretched films are high tensile strength, good stiffness, high transparency, good high and low temperature resistance, good insulation performance, high barrier property, non-toxicity and non-odor. They are very suitable for packaging food and high-end products, and are also widely used in electronic industrial products, photographic film, magnetic tape base material, and especially optical film, which is a material with excellent performance.

[0004] Chinese Patent Publication No. CN113580524B discloses a high-barrier multilayer co-extruded film processing equipment and preparation method, which comprises a base plate, a gantry, an extrusion film blowing mechanism, an expansion stabilizing mechanism, and an extrusion forming mechanism for extruding work after the completion of the film blowing production. The gantry is fixedly arranged at the upper middle part of the base plate. The extrusion film blowing mechanism is arranged at the lower end of the interior of the gantry. The expansion stabilizing mechanism is arranged in the middle part of the gantry. The extrusion forming mechanism is arranged at the upper end of the interior of the gantry. By linking the air outlet of the extrusion film blowing mechanism and the stabilizing structure of the expansion stabilizing mechanism together, the air outlet angle can be automatically adjusted to match the diameter of the blown film bubble when the diameter of the film bubble is changed.

[0005] However, the prior art usually detects the uniformity of the film after stretching is completed, and if the uniformity of the film does not meet the standard, the raw material is wasted. The present application periodically detects the uniformity of the film to adjust the stretching speed of the stretching roller in the stretching roller group, ensuring the production quality of the film and improving the film production efficiency. SUMMARY

[0006] Therefore, the present application provides a high-barrier MDOPE film preparation equipment and method to overcome the problem of low film production efficiency caused by the lack of real-time detection of film uniformity and large film uniformity deviation in the prior art.

[0007] To achieve the above object, in one aspect, the application provides a preparation device of high-barrier MDOPE film, comprising:

[0008] an extruder for melting raw materials and extruding the melt;

[0009] a cooling roller arranged at the head position of the extruder for cooling the melt extruded by the extruder to form a sheet;

[0010] a preheating roller set comprising at least two preheating rollers for preheating the sheet at a set temperature to soften the sheet;

[0011] a stretching module arranged at the output end of the preheating roller set for stretching the softened sheet to form a film, the stretching module comprising a longitudinal stretching roller set and a transverse stretching mechanism, the longitudinal stretching roller set being a set of stretching roller cylinders at a certain speed gradient;

[0012] a film thickness tester arranged at one side of the longitudinal stretching roller set for detecting the uniformity of the film in a cycle and the thickness of the film during the stretching process;

[0013] a winding roller arranged at the output end of the transverse stretching mechanism for winding the film;

[0014] a central control processor connected to the stretching module and the film thickness tester respectively for setting the operating parameters of the stretching module according to the detection results of the film thickness tester, the central control processor comprising a parameter determination unit, a first control unit and a second control unit connected to each other;

[0015] the parameter determination unit determines a preset stretching length and a preset stretching width of the film, and determines a starting stretching speed and a speed gradient of the stretching roller cylinder set based on the preset stretching length;

[0016] the first control unit divides the film into several regions when the uniformity of the film in a cycle does not meet the standard, and calculates the stretching speed adjustment amount of the corresponding stretching roller based on the thickness and stretching adjustment parameters of the film in each region to adjust the stretching speed of the corresponding stretching roller to a corresponding value;

[0017] the second control unit obtains the longitudinal stretching length after the longitudinal stretching is completed, calculates the stretching speed ratio of the actual starting stretching speed to the preset starting stretching speed if the longitudinal stretching length is less than the preset stretching length, and determines the stretching orientation of the film based on the stretching speed ratio.

[0018] Further, the parameter determining unit is provided with a longitudinal stretching ratio interval and a transverse stretching ratio interval, the parameter determining unit acquires the longitudinal length and the transverse length of the sheet material, determines the preset stretching length of the film based on the longitudinal stretching ratio interval and the longitudinal length, and determines the preset stretching width of the film based on the transverse stretching ratio interval and the transverse length.

[0019] Further, the parameter determining unit is provided with a plurality of setting modes for setting the starting stretching speed in the longitudinal stretching roller set and the speed gradient of the longitudinal stretching roller set according to the preset stretching length.

[0020] Each setting mode sets different numerical values for the starting stretching speed and the speed gradient.

[0021] Further, the film thickness tester detects the uniformity of the film in the period during the longitudinal stretching, if the uniformity of the film does not meet the standard, the film in the period is divided into a plurality of regions along the transverse direction of the film according to the spacing of the stretching rollers in the longitudinal stretching roller set, and the thickness of the film in each region is detected in turn, and the first control unit controls the stretching speed of the corresponding stretching roller to decrease or increase according to the thickness.

[0022] Further, the first control unit calculates a stretching adjustment parameter according to the preset stretching length and the preset stretching width of the film, and the current length and the current width of the film when controlling the stretching speed adjustment of the corresponding stretching roller.

[0023] Further, the first control unit calculates the stretching speed adjustment amount of the corresponding stretching roller based on the stretching adjustment parameter.

[0024] The stretching speed adjustment amount includes a stretching speed decrease amount and a stretching speed increase amount.

[0025] Further, the first control unit calculates the thickness difference between the thickness of the film in any region and the standard thickness, and determines the thickness difference level, and determines the adjusted stretching speed of the corresponding stretching roller based on the stretching speed adjustment amount at different difference levels.

[0026] Further, after the longitudinal stretching is completed, the second control unit acquires the longitudinal stretching length, if the longitudinal stretching length is less than the preset stretching length, the second control unit calculates the stretching speed ratio of the actual starting stretching speed to the preset starting stretching speed, and the second control unit determines the stretching orientation of the film based on the stretching speed ratio.

[0027] Further, the device further comprises a human-computer interaction module, and the control instruction is input through the human-computer interaction module.

[0028] On the other hand, the application provides a preparation method of a high-barrier MDOPE film, comprising:

[0029] Step S1, the extruder and the cooling roller cooperate to produce a sheet;

[0030] Step S2, the sheet is preheated by a preheating roller set to soften the sheet;

[0031] Step S3, the parameter determination unit sets the operating parameters of the stretching module, and the softened sheet is stretched through the stretching module;

[0032] Step S4, the first control unit determines the adjustment mode of the stretching roller according to the uniformity of the film in the cycle and the thickness of the film detected by the film thickness tester during stretching;

[0033] Step S5, after the longitudinal stretching is completed, the second control unit calculates the stretching speed ratio of the actual starting stretching speed and the preset starting stretching speed, and determines the stretching orientation of the film based on the stretching speed ratio.

[0034] Compared with the prior art, the beneficial effects of the present application are that, when longitudinal stretching is performed, if the actual stretching speed deviates from the set stretching speed, the film thickness will be uneven, which will further cause the use performance of the film to decrease, and even the transverse stretching cannot be operated, the film thickness tester is arranged to detect the uniformity of the film in real time, and when the uniformity of the film does not meet the standard, the film is divided into regions, the thickness of the film in any region is measured, and the adjustment mode of the corresponding stretching roller is determined according to the thickness, the stretching speed of the stretching roller is adjusted in real time to ensure that the uniformity of the film meets the standard, the operability of the film during transverse stretching is improved, and the use performance of the film is further improved.

[0035] Further, when it is determined that the uniformity of the film in the cycle does not meet the standard, the film is divided into a plurality of regions, each region corresponds to a stretching roller, and then the thickness of the film in each region is detected in sequence, the adjustment mode of the corresponding stretching roller is determined according to the thickness of the film, and the adjustment is more targeted through separate adjustment, thereby further ensuring the uniformity of the film.

[0036] Further, the present application calculates the stretching adjustment parameter based on the preset stretching length and the preset stretching width of the film, the stretching adjustment parameter is a characteristic parameter of film stretching, when the current length of the film approaches the preset stretching length, it indicates that the longitudinal stretching is about to end, at this time the adjustment space of the stretching speed becomes smaller, the stretching adjustment parameter is calculated to reflect the adjustment space of the stretching speed, and the stretching speed reduction and / or the stretching speed increase are determined based on the stretching adjustment parameter, so that the adjustment of the stretching speed of the corresponding stretching roller can better meet the actual requirements, thereby further ensuring the uniformity of the film and improving the production efficiency.

[0037] Further, the first preset difference value and the second preset difference value are arranged to determine the difference level of the thickness difference value, and the stretching speed of the corresponding stretching roller is adjusted to the corresponding value based on the difference level, so that the adjustment of the stretching speed of the corresponding stretching roller can meet the actual requirements, thereby further ensuring the uniformity of the film and improving the production efficiency.

[0038] Further, the biaxially stretched film has several times higher tensile strength and elastic modulus, and the impact strength is obviously different from that of the film without stretching, especially at low temperature, the impact strength is not reduced, that is, the cold resistance is excellent, and at high temperature, the performance is not deteriorated, which makes the use temperature range of the biaxially stretched film wider.

[0039] Further, the biaxially stretched film has several times higher tensile strength and elastic modulus, and the impact strength is obviously different from that of the film without stretching, especially at low temperature, the impact strength is not reduced, that is, the cold resistance is excellent, and at high temperature, the performance is not deteriorated, which makes the use temperature range of the biaxially stretched film wider. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 The structure diagram of the preparation equipment of the high-barrier MDOPE film of the embodiment of the present application is shown in the figure.

[0041] Figure 2 The schematic diagram of the transverse stretching process of the embodiment of the present application is shown in the figure.

[0042] Figure 3 The flow chart of the preparation method of the high-barrier MDOPE film of the embodiment of the present application is shown in the figure.

[0043] In the figure: extruder 1, cooling roller 2, preheating roller group 3, longitudinal stretching roller group 4, transverse stretching mechanism 5, and winding roller 6. DETAILED DESCRIPTION

[0044] In order to make the purpose and advantages of the present application more clear and explicit, the present application is further described below in combination with the embodiments; it should be understood that the specific embodiments described herein are only used to explain the present application, and do not limit the present application.

[0045] The preferred embodiments of the present application are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present application, and are not intended to limit the protection scope of the present application.

[0046] It should be noted that in the description of the present application, the terms of direction or position relationship such as "upper", "lower", "left", "right", "inner", "outer" and the like are based on the direction or position relationship shown in the drawings, which is merely for the convenience of description, and does not indicate or imply that the device or element must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0047] In addition, it should also be noted that in the description of the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, or the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0048] Please refer to Figure 1 The preparation equipment of the high-barrier MDOPE film of the embodiment of the present application is shown in the figure, and the preparation equipment of the high-barrier MDOPE film of the present application comprises:

[0049] The extruder 1 is used to melt and extrude the melt;

[0050] The cooling roller 2 is arranged at the head position of the extruder 1, and is used to cool the melt extruded by the extruder 1 to form a sheet;

[0051] The preheating roller group 3 comprises at least two preheating rollers, which preheat the sheet at a set temperature to soften the sheet;

[0052] The stretching module is arranged at the output end of the preheating roller group 3, and is used to stretch the softened sheet to form a film, the stretching module comprises a longitudinal stretching roller group 4 and a transverse stretching mechanism 5, and the longitudinal stretching roller group 4 is a group of stretching roller cylinders with a certain speed gradient;

[0053] The film thickness tester is arranged on one side of the longitudinal stretching roller group 4, and is used to detect the uniformity of the film in a period and the thickness of the film during the stretching process;

[0054] The winding roller 6 is arranged at the output end of the transverse stretching mechanism 5, and is used to wind the film;

[0055] The central control processor is connected with the stretching module and the film thickness tester respectively, and is used to set the operation parameters of the stretching module according to the detection result of the film thickness tester, and the central control processor comprises a parameter determination unit, a first control unit and a second control unit connected with each other;

[0056] The parameter determination unit determines a preset stretching length and a preset stretching width of the film, and determines a starting stretching speed and a speed gradient of the longitudinal stretching roller group 4 based on the preset stretching length;

[0057] The first control unit divides the film into several regions when the uniformity of the film in a period does not meet the standard, and calculates the stretching speed adjustment amount of the corresponding stretching roller to adjust the stretching speed of the corresponding stretching roller to the corresponding value according to the thickness and the stretching adjustment parameter of the film in each region.

[0058] The second control unit obtains the longitudinal stretching length after the longitudinal stretching is completed, and calculates the stretching speed ratio of the actual starting stretching speed to the preset starting stretching speed if the longitudinal stretching length is less than the preset stretching length, and determines the stretching orientation of the film based on the stretching speed ratio.

[0059] In this embodiment, the manufacturing of the sheet through the extrusion process is a mature prior art, and will not be described in detail.

[0060] In this embodiment, the transverse stretching mechanism 5 is used to automatically open and close the clamps through mechanical devices to complete the film conveying and stretching work, which is a conventional technology and will not be described in detail.

[0061] The film thickness tester selected in this embodiment is one or several of a magnetic induction coating thickness tester, an eddy current coating thickness tester, and a fluorescent X-ray instrument coating thickness tester.

[0062] When the actual stretching speed deviates from the set stretching speed during longitudinal stretching, the film thickness will be uneven. The film thickness tester is arranged to detect the uniformity of the film in a period in real time, and the film is divided into regions when the uniformity of the film does not meet the standard. The thickness of the film in any region is measured, and the adjustment mode of the corresponding stretching roller is determined according to the thickness. The stretching speed of the stretching roller is adjusted in real time to ensure that the uniformity of the film meets the standard, thereby improving the operability of the film during transverse stretching and improving the use performance of the film.

[0063] Specifically, the parameter determination unit is provided with a longitudinal stretching ratio interval (a, b) and a transverse stretching ratio interval (a1, b1). The parameter determination unit obtains the longitudinal length l and the transverse length d of the sheet, determines the preset stretching length L of the film based on the longitudinal stretching ratio interval and the longitudinal length, and determines the preset stretching width D of the film based on the transverse stretching ratio interval and the transverse length.

[0064] The longitudinal length is the length of the sheet along the arrangement direction of the equipment, and the transverse length is the length in the direction perpendicular to the longitudinal direction of the sheet. The preset stretching length is greater than the preset stretching width.

[0065] In the embodiment, the preset stretching length is a*l-b*l, and the preset stretching width is a1*d-b1*d. In the embodiment, the preset stretching length is set to be a*l-b*l The preset stretching width is set

[0066] The longitudinal stretching ratio interval (a, b) and the transverse stretching ratio interval (a1, b1) can be set according to the actual material and actual needs for production. In the embodiment, the longitudinal stretching ratio interval is set to be (3.6, 4.2), and the transverse stretching ratio interval is set to be (3.2, 3.8).

[0067] Specifically, the parameter determination unit sets the starting stretching speed of the longitudinal stretching roller group 4 and the speed gradient of the longitudinal stretching roller group 4 according to the preset stretching length. The parameter determination unit is provided with a preset standard stretching length Lb, a preset starting stretching speed V0, and a preset speed gradient v0. The parameter determination unit determines the starting stretching speed and the speed gradient according to the length difference AL of the preset stretching length L and the preset standard stretching length Lb, AL=|L-Lb|.

[0068] If AL<AL1, the parameter determination unit determines to use the first speed adjustment coefficient β1 to determine the starting stretching speed V and the speed gradient v.

[0069] If AL1≤AL<AL2, the parameter determination unit determines to use the second speed adjustment coefficient β2 to determine the starting stretching speed V and the speed gradient v.

[0070] If AL≥AL2, the parameter determination unit determines to use the third speed adjustment coefficient β3 to determine the starting stretching speed V and the speed gradient v.

[0071] When the parameter determination unit uses the kth speed adjustment coefficient to determine the starting stretching speed V and the speed gradient v, the stretching speed V is set to be (1±βk)×V0, and the speed gradient v is set to be (1±βk)×v0.

[0072] When the parameter determination unit uses the kth speed adjustment coefficient to determine the starting stretching speed V and the speed gradient v, the stretching speed V is set to be (1±βk)×V0, and the speed gradient v is set to be (1±βk)×v0.

[0073] When the parameter determination unit uses the kth speed adjustment coefficient to determine the starting stretching speed V and the speed gradient v, the stretching speed V is set to be (1±βk)×V0, and the speed gradient v is set to be (1±βk)×v0.

[0074] When the parameter determination unit uses the kth speed adjustment coefficient to determine the starting stretching speed V and the speed gradient v, the stretching speed V is set to be (1±βk)×V0, and the speed gradient v is set to be (1±βk)×v0.

[0075] Wherein, AL1 is the first preset length difference, AL2 is the second preset length difference, AL1 < AL2. The embodiment sets 0.08 < β1 < β2 < β3 < 0.18, and the embodiment preferably β1 = 0.1, β2 = 0.13, and β3 = 0.16. In the embodiment, when the speed adjustment coefficient satisfies 0.08 < β1 < β2 < β3 < 0.18, the uniformity of the film can be stable within the set stretching ratio interval.

[0076] In the embodiment, the calculation method of AL1 and AL2 is AL1 = 0.05 x L0 and AL2 = 0.08 x L0.

[0077] In the embodiment, the starting point stretching speed in the longitudinal stretching roller group 4 and the speed gradient in the longitudinal stretching roller group 4 can be automatically set by the parameter determination unit or manually set by the man-machine interaction module. The parameter setting is a conventional technique in the art, and the embodiment will not be described in detail.

[0078] Specifically, the film thickness tester detects the uniformity of the film in a period during the longitudinal stretching process. If the uniformity of the film does not meet the standard, the film in the period is divided into several regions along the transverse direction of the film according to the spacing of each stretching roller in the longitudinal stretching roller group 4, and the thickness of the film in each region is detected in turn. The first control unit controls the stretching speed of the corresponding stretching roller to decrease or increase according to the thickness, wherein,

[0079] If the thickness is less than e1 x the standard thickness, the first control unit controls the stretching roller corresponding to the thickness to decrease the stretching speed;

[0080] If the thickness is greater than e2 x the standard thickness, the first control unit controls the stretching roller corresponding to the thickness to increase the stretching speed;

[0081] Wherein, e1 is the first boundary coefficient, e2 is the second boundary coefficient, 0.95 < e1 < 1 < e2 < 1.05. The first boundary coefficient e1 and the second boundary coefficient e2 can be set according to the actual thickness allowable deviation, and the embodiment does not make specific limitation.

[0082] The values of the first boundary coefficient and the second boundary coefficient are actually the allowable floating interval of the film thickness, which is set according to the actual quality requirement. According to the historical data, when the value range of e1 and e2 is 0.95 < e1 < 1 < e2 < 1.05, the consistency of the film thickness is good. The embodiment preferably e1 = 0.96 and e2 = 1.03 to ensure the consistency of the film thickness.

[0083] In the embodiment, the time for the film to be stretched to the length of the longitudinal stretching roller set 4 is recorded as a period, and when detecting the uniformity of the film, the film thickness tester obtains the thickness values of at least 100 points on the film, and calculates the variance value of the 100 thickness values, and if the variance value exceeds the preset standard value, it is determined that the uniformity of the film does not meet the standard.

[0084] Specifically, when detecting the thickness of the film in each region, the film thickness tester obtains the thickness values of at least 20 points on the film, and calculates the mean value of the 20 thickness values, and the mean value is taken as the thickness of the film in the region.

[0085] When it is determined that the uniformity of the film in the period does not meet the standard, the film is divided into a plurality of regions, each region corresponds to a stretching roller, and then the thickness of the film in each region is detected in turn, the adjustment mode of the corresponding stretching roller is determined according to the thickness of the film, and the adjustment is more targeted through separate adjustment, thereby further ensuring the uniformity of the film.

[0086] Specifically, the first control unit calculates the stretching adjustment parameter F according to the following formula, and sets:

[0087]

[0088] Wherein, L is a preset stretching length, L0 is a current length of the film, D is a preset stretching width, and D0 is a current width of the film.

[0089] Specifically, the first control unit calculates the stretching speed reduction amount Vx according to the stretching adjustment parameter, and sets

[0090]

[0091] Or, the stretching speed increase amount Vz is calculated according to the stretching adjustment parameter, and is set to

[0092]

[0093] Wherein, V1 is the current stretching speed of the corresponding stretching roller.

[0094] The present application calculates the stretching adjustment parameter based on the preset stretching length and the preset stretching width of the film, and the stretching adjustment parameter is a characteristic parameter of the film stretching. When the current length of the film approaches the preset stretching length, it indicates that the longitudinal stretching is about to end, at this time the adjustment space of the stretching speed becomes smaller. The stretching adjustment parameter is calculated to reflect the adjustment space of the stretching speed, and the stretching speed reduction amount Vx and / or the stretching speed increase amount Vz are determined based on the stretching adjustment parameter, so that the adjustment of the stretching speed of the corresponding stretching roller can better meet the actual requirements, thereby further ensuring the uniformity of the film and improving the production efficiency.

[0095] Specifically, the first control unit calculates a thickness difference D of any of the area films from a standard thickness, sets the thickness difference D=standard thickness-film thickness, and determines the adjusted stretching speed of the corresponding stretching roller according to the thickness difference D;

[0096] If the first thickness difference level is reached, the first control unit reduces the stretching speed of the corresponding stretching roller to Va or increases the stretching speed to Va', with Va=V1-α1×Vx and Va'=V1+α1×Vz;

[0097] If the second thickness difference level is reached, the first control unit reduces the stretching speed of the corresponding stretching roller to Vb or increases the stretching speed to Vb', with Vb=V1-α2×Vx and Vb'=V1+α2×Vz;

[0098] If the third thickness difference level is reached, the first control unit reduces the stretching speed of the corresponding stretching roller to Vc or increases the stretching speed to Vc', with Vc=V1-α3×Vx and Vc'=V1+α3×Vz;

[0099] wherein Vc<Vb<Va<V1<Va'<Vb'<Vc', α1 is a first stretching speed adjustment coefficient, α2 is a second stretching speed adjustment coefficient, and α3 is a third stretching speed adjustment coefficient, 0.02<α1<α2<α3<0.08, the stretching speed is reduced when the thickness difference D is positive, and the stretching speed is increased when the thickness difference D is negative.

[0100] Specifically, the first control unit is provided with a first preset difference and a second preset difference, the first preset difference being smaller than the second preset difference, wherein,

[0101] The first thickness difference level satisfies that the thickness difference |D| is less than or equal to the first preset difference;

[0102] The second thickness difference level satisfies that the thickness difference |D| is greater than the first preset difference and less than or equal to the second preset difference;

[0103] The third thickness difference level satisfies that the thickness difference |D| is greater than the second preset difference.

[0104] wherein the first preset difference=0.1×standard thickness, and the second preset difference=0.2×standard thickness.

[0105] The first preset difference and the second preset difference are provided to determine the difference level of the thickness difference, and the stretching speed of the corresponding stretching roller is adjusted to a corresponding value based on the difference level, so that the adjustment of the stretching speed of the corresponding stretching roller can better meet the actual requirements, thereby further ensuring the uniformity of the film and improving the production efficiency.

[0106] Specifically, after the longitudinal stretching is completed, the second control unit acquires the longitudinal stretching length, and if the longitudinal stretching length is less than a preset stretching length, the second control unit calculates a stretching speed ratio B of an actual starting stretching speed to a preset starting stretching speed, and determines the stretching orientation of the film based on the stretching speed ratio.

[0107] Specifically, the second control unit compares the stretching speed ratio with a first preset ratio B1 and a second preset ratio B2 respectively, and determines the stretching orientation according to the comparison result.

[0108] If the stretching speed ratio is greater than the second preset ratio, the second control unit determines the stretching orientation as longitudinal stretching.

[0109] If the stretching speed ratio is less than the first preset ratio, the second control unit determines the stretching orientation as transverse stretching.

[0110] Wherein, 0 < B1 < 1 ≤ B2.

[0111] Specifically, when the second control unit determines the stretching orientation as transverse stretching, the transverse stretching speed is adjusted to 1.2 times of the original value to improve the stability of transverse stretching.

[0112] Specifically, the system further comprises a man-machine interaction module, and the control instruction is input through the man-machine interaction module.

[0113] The film stretched in two directions has several times of improved tensile strength and elastic modulus, and its impact strength is obviously different from that of the film without stretching, especially at low temperature, the impact strength is not reduced, that is, the cold resistance is excellent, and at high temperature, the performance is not deteriorated, which makes the use temperature range of the film stretched in two directions wider.

[0114] The film stretched in two directions has improved transparency and gloss, especially because the spherulite structure is not formed, the refractive index of the film is increased, so that the film has the characteristics of not reducing the gloss and transparency due to damage. Moreover, the electrical properties such as breakdown voltage and volume resistivity are improved to different degrees in the film stretched in two directions.

[0115] The film stretched in two directions has reduced water vapor, oxygen or other gas permeability by 1 / 3-1 / 2, which is particularly important in the food packaging industry.

[0116] Please refer to Figure 3 As shown in the figure, it is a flow chart of the preparation method of the high-barrier MDOPE film according to the embodiment of the application, and the preparation method of the high-barrier MDOPE film according to the application comprises:

[0117] Step S1, the extruder 1 and the cooling roller 2 cooperate to produce a sheet;

[0118] Step S2, the sheet is preheated by the preheating roller group 3 to soften the sheet;

[0119] Step S3, the parameter determination unit sets the operation parameters of the stretching module, and the softened sheet is stretched by the stretching module;

[0120] Step S4, the first control unit determines the adjustment mode of the stretching roller according to the uniformity of the film in the cycle and the thickness of the film detected by the film thickness tester during the stretching process;

[0121] Step S5, after the longitudinal stretching is completed, the second control unit calculates the stretching speed ratio of the actual starting stretching speed and the preset starting stretching speed, and determines the stretching orientation of the film based on the stretching speed ratio.

[0122] So far, the technical solutions of the present application have been described in combination with the preferred embodiments shown in the drawings, but it is easy for those skilled in the art to understand that the protection scope of the present application is obviously not limited to these specific embodiments. Those skilled in the art can make equivalent changes or replacements to the related technical features without departing from the principles of the present application, and the technical solutions after the changes or replacements will fall within the protection scope of the present application.

[0123] The above description is only the preferred embodiments of the present application and is not used to limit the present application; for those skilled in the art, the present application can have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. An apparatus for preparing a high-barrier MDOPE membrane, characterized in that, include: An extruder is used to melt raw materials and extrude the melt. A cooling roller, which is located at the die head of the extruder, is used to cool the molten material extruded by the extruder to form a sheet; A preheating roller assembly, comprising at least two preheating rollers, wherein the preheating rollers preheat the sheet at a set temperature to soften the sheet; A stretching module is provided at the output end of the preheating roller group to stretch the softened sheet to form a film. The stretching module includes a longitudinal stretching roller group and a transverse stretching mechanism. The longitudinal stretching roller group is a set of stretching rollers with a certain speed gradient. A film thickness tester is installed on one side of the longitudinal stretching roller assembly to detect the uniformity and thickness of the film during the stretching process. A take-up roller, which is disposed at the output end of the transverse stretching mechanism, is used to wind up the film; The central control processor is connected to the tensile module and the film thickness tester respectively, and is used to set the operating parameters of the tensile module according to the test results of the film thickness tester. The central control processor includes a parameter determination unit, a first control unit and a second control unit that are connected to each other. The parameter determination unit determines the preset stretching length and preset stretching width of the film, and determines the starting stretching speed and speed gradient of the stretching roller group based on the preset stretching length. The parameter determination unit is provided with a longitudinal stretching ratio range and a transverse stretching ratio range. When the uniformity of the film does not meet the standard within the cycle, the first control unit divides the film into several regions and calculates the stretching speed adjustment amount of the corresponding stretching roller according to the thickness of the film in each region and the stretching adjustment parameters, so as to adjust the stretching speed of the corresponding stretching roller to the corresponding value. After the longitudinal stretching is completed, the second control unit obtains the longitudinal stretching length. If the longitudinal stretching length is less than the preset stretching length, it calculates the stretching speed ratio between the actual starting stretching speed and the preset starting stretching speed, and determines the stretching orientation of the film based on the stretching speed ratio. When the second control unit determines the stretching orientation as transverse stretching, it adjusts the transverse stretching speed to 1.2 times the original speed.

2. The apparatus for preparing the high-barrier MDOPE membrane according to claim 1, characterized in that, The parameter determination unit acquires the longitudinal length and transverse length of the sheet, determines the preset stretch length of the film based on the longitudinal stretch ratio range and the longitudinal length, and determines the preset stretch width of the film based on the transverse stretch ratio range and the transverse length.

3. The apparatus for preparing the high-barrier MDOPE membrane according to claim 2, characterized in that, The parameter determination unit is provided with several setting methods for setting the starting stretching speed and the speed gradient of the longitudinal stretching roller group according to the preset stretching length. Each setting method has different values ​​for the starting stretch speed and speed gradient.

4. The apparatus for preparing the high-barrier MDOPE membrane according to claim 3, characterized in that, The film thickness tester detects the uniformity of the film within a cycle during the longitudinal stretching process. If the uniformity of the film does not meet the standard, the film within the cycle is divided into several regions along the transverse direction of the film according to the spacing of each stretching roller in the longitudinal stretching roller group, and the thickness of the film in each region is detected in turn. The first control unit controls the stretching speed of the corresponding stretching roller to decrease or increase according to the thickness. The first control unit is used to divide the film into several regions according to the spacing of each stretching roller in the longitudinal stretching roller group during the longitudinal stretching process of the film thickness tester when the uniformity of the film within the cycle does not meet the standard. The thickness of the film in each region is detected in turn to control the stretching speed of the corresponding stretching roller.

5. The apparatus for preparing the high-barrier MDOPE membrane according to claim 4, characterized in that, When the first control unit controls the stretching speed adjustment of the corresponding stretching roller, it calculates the stretching adjustment parameters based on the preset stretching length and preset stretching width of the film, as well as the current length and current width of the film.

6. The apparatus for preparing the high-barrier MDOPE membrane according to claim 5, characterized in that, The first control unit calculates the tension speed adjustment amount of the corresponding tension roller based on the tension adjustment parameters; The tension speed adjustment includes a decrease in tension speed and an increase in tension speed.

7. The apparatus for preparing a high-barrier MDOPE membrane according to claim 6, characterized in that, The first control unit calculates the thickness difference between the thickness of the film in any of the regions and the standard thickness, and determines the thickness difference level. Under different difference levels, it determines the stretching speed of the corresponding stretching roller after adjustment based on the stretching speed adjustment amount.

8. The apparatus for preparing a high-barrier MDOPE membrane according to claim 7, characterized in that, After longitudinal stretching is completed, the second control unit obtains the longitudinal stretching length. If the longitudinal stretching length is less than the preset stretching length, the second control unit calculates the stretching speed ratio between the actual starting stretching speed and the preset starting stretching speed. The second control unit determines the stretching orientation of the film based on the stretching speed ratio.

9. The apparatus for preparing a high-barrier MDOPE membrane according to claim 1, characterized in that, It also includes a human-computer interaction module, through which control commands are input.

10. A method for preparing a high-barrier MDOPE membrane according to any one of claims 1-9, characterized in that, include: Step S1, the extruder (1) and cooling roller (2) work together to produce sheet material; In step S2, the sheet is preheated by the preheating roller group (3) to soften the sheet; Step S3: The parameter determination unit sets the operating parameters of the stretching module, and the softened sheet is stretched through the stretching module. Step S4: The first control unit determines the adjustment method of the stretching roller based on the uniformity of the film and the thickness of the film during the stretching process detected by the film thickness tester. Step S5: After longitudinal stretching is completed, the second control unit calculates the stretching speed ratio between the actual starting stretching speed and the preset starting stretching speed, and determines the stretching orientation of the film based on the stretching speed ratio.

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