An online monitoring method and application of thickness of multi-layer co-extruded film material products

Abstract

The present invention belongs to the technical field of online monitoring, and discloses an online monitoring method and application of the thickness of a multi-layer co-extruded film material product. The online monitoring method comprises the following steps: preparing a monochrome film sample, preparing another monochrome film sample, overlapping the monochrome samples to form a three-layer composite film, measuring the Lab value, and obtaining a relationship curve between the Lab value and the film thickness; inputting the relationship curve into an online detection device, performing online detection on the pre-designed multi-layer co-extruded film material product, and calculating the thickness of each layer of the multi-layer co-extruded film material sample in the online production process according to the corresponding relationship between the Lab value and the thickness in the relationship curve, thereby realizing online monitoring of different thicknesses of multi-layer co-extruded film material products. The online monitoring method solves the problem that it is difficult to monitor the thickness and gram weight of each layer of multi-layer co-extruded film materials online, and is of great value for improving the quality control of multi-layer co-extruded film materials and improving the detection level.

Description

Technical Field

[0001] The invention belongs to the technical field of online monitoring, and in particular relates to an online monitoring method and application of the thickness of a multi-layer co-extruded film material product. Background Art

[0002] In the field of polymer functional films, in order to solve the problem of having multiple properties of films at the same time, composite structural films are usually prepared by coating, hot pressing lamination or multi-layer co-extrusion. In order to monitor the thickness and gram weight of the film, a thickness gauge based on the principle of radiation source is usually used for online monitoring. However, for processes such as coating and hot pressing lamination that can be processed in sections, the thickness and gram weight of different structural layers can be monitored separately, while for the one-time multi-layer co-extrusion processing technology, especially when the components of each layer are basically similar and the ability to absorb radiation is basically the same, it is difficult to define the precise thickness and gram weight of each layer structure, which makes it difficult to accurately control the quality of multi-layer co-extruded films.

[0003] Therefore, there is an urgent need to provide a method for accurately monitoring the thickness of a multilayer film during the preparation of a multilayer film by a one-time multilayer co-extrusion process, thereby helping to obtain a film of precise quality. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention provides an online monitoring method and application of the thickness of a multi-layer co-extruded film material product. The online monitoring method of the present invention can accurately monitor the thickness of a film product prepared by a one-time multi-layer co-extrusion process, thereby obtaining a film of precise quality.

[0005] A first aspect of the present invention provides an online monitoring method for the thickness of a multi-layer co-extruded film material product.

[0006] Specifically, an online monitoring method for the thickness of a multi-layer co-extruded film material product comprises the following steps:

[0007] (1) Preparation of monochrome film samples: prepare an A1 layer film with a blue masterbatch, a colorless and transparent B1 layer film with a thickness of a1 μm, a colorless and transparent C1 layer film with a thickness of b1 μm, and a colorless and transparent C1 layer film with a thickness of c1 μm;

[0008] A2 layer film with blue masterbatch added, a colorless transparent B2 layer film with a thickness of a2 μm, a colorless transparent C2 layer film with a thickness of b2 μm, and a colorless transparent C2 layer film with a thickness of c2 μm were prepared respectively;

[0009] A3 layer film with blue masterbatch added, a colorless transparent B3 layer film with a thickness of a3 μm, a colorless transparent C3 layer film with a thickness of b3 μm, and a colorless transparent C3 layer film with a thickness of c3 μm were prepared respectively;

[0010] The A1 film, the B1 film, and the C1 film are sequentially stacked to form an A1 / B1 / C1 composite film, the A2 film, the B2 film, and the C2 film are stacked to form an A2 / B2 / C2 composite film, and the A3 film, the B3 film, and the C3 film are stacked to form an A3 / B3 / C3 composite film, and the Lab value test is performed to obtain the Lab values ​​corresponding to the composite films of different thicknesses;

[0011] (2) Preparation of another monochrome film sample: a colorless transparent A4 film with a thickness of 4 μm, a colorless transparent B4 film with a thickness of 4 μm, and a C4 film with a thickness of 4 μm with yellow masterbatch added were prepared respectively;

[0012] A colorless transparent A5 film with a thickness of a5 μm, a colorless transparent B5 film with a thickness of b5 μm, and a C5 film with a thickness of c5 μm with a yellow masterbatch added were prepared respectively;

[0013] A colorless and transparent A6 film with a thickness of a6 μm, a colorless and transparent B6 film with a thickness of b6 μm, and a C6 film with a thickness of c6 μm with a yellow masterbatch added were prepared respectively;

[0014] The A4 film, the B4 film, and the C4 film are stacked to form an A4 / B4 / C4 composite film, the A5 film, the B5 film, and the C5 film are stacked to form an A5 / B5 / C5 composite film, and the A6 film, the B6 film, and the C6 film are stacked to form an A6 / B6 / C6 composite film, and the Lab value test is performed to obtain the Lab values ​​corresponding to the composite films of different thicknesses;

[0015] (3) laminating one of the monochromatic films A1-A6, one of B1-B6 and one of C1-C6 of different thicknesses prepared in step (1) and step (2) to form a three-layer composite film (i.e., a three-layer composite film with a structure of A\B\C is to be formed), measuring the Lab value of the three-layer composite film after lamination, and obtaining a relationship curve between the Lab value and the film thickness after lamination at different ratios;

[0016] (4) The relationship curve obtained in step (3) is input into an online detection device to perform online detection on the pre-designed multi-layer co-extruded film material product. The thickness of each layer of the multi-layer co-extruded film material sample in the online production process is calculated based on the corresponding relationship between the Lab value and the thickness in the relationship curve, thereby realizing online monitoring of different thicknesses of the multi-layer co-extruded film material product.

[0017] Preferably, b1, b2, and b3 are equal.

[0018] Preferably, c1, c2, and c3 are equal.

[0019] Preferably, a4, a5, and a6 are equal.

[0020] Preferably, b1, b2, b3, b4, b5, and b6 are all greater than a1, a2, a3, a4, a5, a6, c1, c2, c3, c4, c5, and c6.

[0021] Preferably, the value range of b1, b2, b3, b4, b5, and b6 is 15-25, and more preferably 20-22.

[0022] Preferably, the value range of a1, a2, a3, a4, a5, a6, c1, c2, c3, c4, c5, and c6 is less than 5, and more preferably 1-3.

[0023] Preferably, the pre-designed multi-layer co-extruded film material product includes a thickness of x μm A layer, b y μm B layer, c x μm C layer.

[0024] Preferably, layer A in the pre-designed multi-layer co-extruded film material product contains blue masterbatch, and layer C contains yellow masterbatch.

[0025] For example, the pre-designed multi-layer co-extruded film material product has a layer A thickness of 2 μm (blue), a layer B thickness of 20 μm (colorless and transparent), and a layer C thickness of 2 μm (yellow). The thickness of the middle colorless and transparent layer B is calculated by subtracting the Lab-converted thickness of the A and C layers from the total thickness actually measured by the thickness gauge, thereby achieving online measurement of different thicknesses of the three-layer co-extruded film material product.

[0026] Preferably, after step (4), step (5) is further included, and the content of step (5) is as follows:

[0027] The monitoring results are analyzed and evaluated to determine whether the multi-layer co-extruded film material product meets the quality requirements. If it meets the quality requirements, the subsequent production steps are continued; if it does not meet the quality requirements, the multi-layer co-extruded film material product needs to be adjusted and repaired in thickness.

[0028] A second aspect of the present invention provides an application of an online monitoring method for the thickness of a multi-layer co-extruded film material product.

[0029] The invention discloses an online monitoring method for the thickness of a multi-layer co-extruded film material product and its application in the preparation of a multi-layer film.

[0030] An online visual detection instrument includes a relationship curve between the Lab value and the film thickness obtained by the above-mentioned online monitoring method.

[0031] The online visual detection instrument is based on traditional high-speed camera and defect detection and analysis software and hardware, and adds a relationship curve between Lab value and film thickness, so as to analyze and compare the color and thickness of the film surface, and form an instant calculation and feedback of the Lab value. At the same time, according to the relationship curve between Lab value and film thickness, it is converted into calculation and monitoring of the thickness of different layers, so as to realize the detection and monitoring of the thickness of each layer of the multi-layer co-extruded film.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] The online monitoring method for the thickness of the multi-layer co-extruded film material product of the present invention solves the problem that it is difficult to monitor the thickness and gram weight of each layer of the multi-layer co-extruded film material online, and has great value for improving the quality control of the multi-layer co-extruded film material and improving the detection level. Through the online monitoring of the Lab value, it is not only qualitative but also quantitative to judge the quality problems of the multi-layer co-extruded film material product, and accurately identify the problems such as uneven thickness and flaws. The methods and tools adopted have the advantages of non-contact and non-destructive detection, and can play an important role in the fields of material science, thin film technology and online detection technology, and improve the detection accuracy of product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Schematic diagram of the process of online monitoring the thickness of a multi-layer co-extruded film material product in Example 1. DETAILED DESCRIPTION

[0035] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.

[0036] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0037] The ABC three-layer co-extruded film is prepared by using a three-screw combined with an in-mold composite three-layer die head. Layer A is a transparent polypropylene film or a polypropylene film with 5% by mass of blue masterbatch added, layer C is a transparent polypropylene film or a polypropylene film with 5% by mass of yellow masterbatch added, and layer B is a transparent polypropylene film. The blue masterbatch and the yellow masterbatch are conventional products commercially available in this field.

[0038] The actual thickness measurement method for each film is as follows:

[0039] If there is a color difference between layers, the specific thickness of each layer can be tested by observing under a metallographic microscope. The specific operation is to align the position of the film to be tested with the fixture plane, tighten the fixture screws to clamp the film, use a blade to cut off the film protruding from the fixture plane, and observe and test under a metallographic microscope, so that the thickness of each layer can be clearly measured.

[0040] Example 1

[0041] An online monitoring method for the thickness of a multi-layer co-extruded film material (i.e., an ABC three-layer co-extruded polypropylene film material) comprises the following steps:

[0042] (1) Preparation of monochrome film samples: Prepare A1 layer film (polypropylene film) with blue masterbatch added, with a thickness of 1 μm, B1 layer film (polypropylene film) with a thickness of 20 μm, and C1 layer film (polypropylene film) with a thickness of 2 μm;

[0043] A2 layer film with a blue masterbatch added, with a thickness of 2 μm, a colorless and transparent B2 layer film with a thickness of 20 μm, and a colorless and transparent C2 layer film with a thickness of 2 μm were prepared respectively;

[0044] A3 layer film with a blue masterbatch added, with a thickness of 3 μm, a colorless and transparent B3 layer film with a thickness of 20 μm, and a colorless and transparent C3 layer film with a thickness of 2 μm were prepared respectively;

[0045] The A1 film, the B1 film, and the C1 film are sequentially stacked to form an A1 / B1 / C1 composite film, the A2 film, the B2 film, and the C2 film are sequentially stacked to form an A2 / B2 / C2 composite film, and the A3 film, the B3 film, and the C3 film are sequentially stacked to form an A3 / B3 / C3 composite film. The Lab value test is performed to obtain the Lab values ​​corresponding to the composite films of different thicknesses. The results are shown in Table 1.

[0046] Table 1

[0047]

[0048]

[0049] (2) Preparation of another single-color film sample: a colorless transparent A4 film with a thickness of 2 μm, a colorless transparent B4 film with a thickness of 20 μm, and a C4 film with a thickness of 1 μm with a yellow masterbatch added were prepared respectively;

[0050] A colorless transparent A5 film with a thickness of 2 μm, a colorless transparent B5 film with a thickness of 20 μm, and a C5 film with a thickness of 2 μm with a yellow masterbatch added were prepared respectively;

[0051] A colorless and transparent A6 film with a thickness of 2 μm, a colorless and transparent B6 film with a thickness of 20 μm, and a C6 film with a thickness of 3 μm with a yellow masterbatch added were prepared respectively;

[0052] The A4 film, the B4 film, and the C4 film are sequentially stacked to form an A4 / B4 / C4 composite film, the A5 film, the B5 film, and the C5 film are sequentially stacked to form an A5 / B5 / C5 composite film, and the A6 film, the B6 film, and the C6 film are sequentially stacked to form an A6 / B6 / C6 composite film. The Lab value test is performed to obtain the Lab values ​​corresponding to films of different thicknesses. The results are shown in Table 2.

[0053] Table 2

[0054]

[0055]

[0056] (3) laminating one of the monochromatic films A1-A6, one of B1-B6 and one of C1-C6 of different thicknesses prepared in step (1) and step (2) to form a three-layer composite film (i.e., a three-layer composite film of a structure of A\B\C is to be formed), the specific combination is shown in Table 3, and after laminating, the Lab value of the three-layer composite film is measured to obtain a relationship curve between the Lab value and the film thickness after laminating at different ratios;

[0057] Table 3

[0058]

[0059] The relationship between L value, a value, b value and the thickness of each film layer is as follows:

[0060] L value = 99.6313 + (-3.143) * A layer thickness + (-0.3184) * C layer thickness (Formula 1);

[0061] a value = 0.08 + (-0.5485) * A layer thickness + (-0.6238) * C layer thickness (Formula 2);

[0062] b value = -0.4168 + (-3.2614) * A layer thickness + 4.211 * C layer thickness (Formula 3);

[0063] During online detection, the thickness of layer A and layer C are calculated in reverse based on the measured L value, a value, and b value. The specific method is to write a computer program to automatically calculate. The following are the algorithm steps:

[0064] A three-dimensional coordinate system is established, with the x-axis being the thickness of layer A, the y-axis being the thickness of layer C, and the z-axis being the L value. Then, equation 1 represents a plane, which is recorded as plane 1;

[0065] A three-dimensional coordinate system is established, with the x-axis being the thickness of layer A, the y-axis being the thickness of layer C, and the z-axis being the value of a. Then, equation 2 represents a plane, which is recorded as plane 2;

[0066] A three-dimensional coordinate system is established, with the x-axis being the thickness of layer A, the y-axis being the thickness of layer C, and the z-axis being the b value. Then, equation 3 represents a plane, which is recorded as plane 3;

[0067] In general, planes 1, 2, and 3 will intersect at three straight lines (denoted as u, v, and w). Take the projection of straight lines u, v, and w on the xy coordinate plane to obtain straight lines u', v', and w'. Straight lines u', v', and w' will intersect at three points (denoted as p, q, and r). Take the centroid of the triangle formed by the three points p, q, and r to determine the only point.

[0068] The x coordinate of this point is the thickness of layer A, and the y coordinate is the thickness of layer C.

[0069] (4) inputting the relationship curve obtained in step (3) into an online detection device, performing online detection on the pre-designed multi-layer co-extruded film material product, and calculating the thickness of each layer of the multi-layer co-extruded film material sample in the online production process according to the corresponding relationship between the Lab value and the thickness in the relationship curve, thereby realizing online monitoring of different thicknesses of the multi-layer co-extruded film material product;

[0070] The pre-designed multi-layer co-extruded film material product has a layer A thickness of 2 μm (containing blue masterbatch), a layer B thickness of 20 μm (colorless and transparent), and a layer C thickness of 2 μm (containing yellow masterbatch). The thickness of the middle colorless and transparent layer B is calculated by subtracting the Lab-converted thickness of the A and C layers from the total thickness measured by the thickness gauge. In this way, online measurement of different thicknesses of the three-layer co-extruded film material product is achieved. The corresponding monitoring results and the thickness deviation of each layer (the smaller the deviation, the higher the accuracy) are shown in Table 4 (Table 4 gives the results of 5 experiments).

[0071] Table 4

[0072]

[0073]

[0074] It can be seen from Table 4 that the online monitoring thickness deviation of each layer obtained by the method of the present invention is very small, indicating that the online monitoring accuracy is very high.

[0075] After step (4) is completed, step (5) is also included. The content of step (5) is as follows:

[0076] The monitoring results are analyzed and evaluated to determine whether the multi-layer co-extruded film material product meets the quality requirements. If it meets the quality requirements, the subsequent production steps are continued; if it does not meet the quality requirements, the multi-layer co-extruded film material product needs to be adjusted and repaired in thickness.

[0077] Figure 1 Schematic diagram of the process of online monitoring the thickness of a multi-layer co-extruded film material product in Example 1.

[0078] The above are the specific steps of this embodiment. Through this method, the online detection of multi-layer co-extruded film material products can be effectively realized, and the detection accuracy of product quality can be improved.

Claims

1. An online monitoring method for the thickness of a multi-layer co-extruded film material product, characterized in that: The following steps are involved: (1) Preparation of monochrome film samples: prepare an A1 layer film with a blue masterbatch, a colorless and transparent B1 layer film with a thickness of a1 μm, a colorless and transparent C1 layer film with a thickness of b1 μm, and a colorless and transparent C1 layer film with a thickness of c1 μm; A2 layer film with blue masterbatch added, a colorless transparent B2 layer film with a thickness of a2 μm, a colorless transparent C2 layer film with a thickness of b2 μm, and a colorless transparent C2 layer film with a thickness of c2 μm were prepared respectively; A3 layer film with blue masterbatch added, a colorless transparent B3 layer film with a thickness of a3 μm, a colorless transparent C3 layer film with a thickness of b3 μm, and a colorless transparent C3 layer film with a thickness of c3 μm were prepared respectively; The A1 film, the B1 film, and the C1 film are sequentially stacked to form an A1 / B1 / C1 composite film, the A2 film, the B2 film, and the C2 film are sequentially stacked to form an A2 / B2 / C2 composite film, and the A3 film, the B3 film, and the C3 film are sequentially stacked to form an A3 / B3 / C3 composite film, and a Lab value test is performed to obtain the Lab values ​​corresponding to the composite films of different thicknesses; (2) Preparation of another single-color film sample: a colorless transparent A4 film with a thickness of 4 μm, a colorless transparent B4 film with a thickness of 4 μm, and a C4 film with a thickness of 4 μm with a yellow masterbatch added were prepared respectively; A colorless transparent A5 film with a thickness of a5 μm, a colorless transparent B5 film with a thickness of b5 μm, and a C5 film with a thickness of c5 μm with a yellow masterbatch added were prepared respectively; A colorless and transparent A6 film with a thickness of a6 μm, a colorless and transparent B6 film with a thickness of b6 μm, and a C6 film with a thickness of c6 μm with a yellow masterbatch added were prepared respectively; The A4 film, the B4 film, and the C4 film are sequentially stacked to form an A4 / B4 / C4 composite film, the A5 film, the B5 film, and the C5 film are sequentially stacked to form an A5 / B5 / C5 composite film, and the A6 film, the B6 film, and the C6 film are sequentially stacked to form an A6 / B6 / C6 composite film, and the Lab value test is performed to obtain the Lab values ​​corresponding to the composite films of different thicknesses; (3) laminating one of the monochromatic films A1-A6, one of B1-B6 and one of C1-C6 of different thicknesses prepared in step (1) and step (2) to form a three-layer composite film, measuring the Lab value of the three-layer composite film after lamination, and obtaining a relationship curve between the Lab value and the film thickness after lamination at different ratios; (4) The relationship curve obtained in step (3) is input into an online detection device to perform online detection on the pre-designed multi-layer co-extruded film material product. The thickness of each layer of the multi-layer co-extruded film material sample in the online production process is calculated based on the corresponding relationship between the Lab value and the thickness in the relationship curve, thereby realizing online monitoring of different thicknesses of the multi-layer co-extruded film material product.

2. The online monitoring method according to claim 1, characterized in that: The b1, b2, and b3 are equal.

3. The online monitoring method according to claim 1, characterized in that: The c1, c2, and c3 are equal.

4. The online monitoring method according to claim 1, characterized in that: The a4, a5 and a6 are equal.

5. The online monitoring method according to claim 1, characterized in that: The b1, b2, b3, b4, b5, and b6 are all greater than a1, a2, a3, a4, a5, a6, c1, c2, c3, c4, c5, and c6.

6. The online monitoring method according to claim 1, characterized in that: The value range of b1, b2, b3, b4, b5 and b6 is 15-25.

7. The online monitoring method according to claim 1, characterized in that: The value range of a1, a2, a3, a4, a5, a6, c1, c2, c3, c4, c5, and c6 is less than 5.

8. The online monitoring method according to claim 1, characterized in that: The pre-designed multi-layer co-extruded film material product sequentially comprises a x μm A layer, b y μm B layer, c x μm; and / or, the A layer in the pre-designed multi-layer co-extruded film material product contains blue masterbatch, and the C layer contains yellow masterbatch.

9. Use of the online monitoring method according to any one of claims 1 to 8 in the preparation of a multilayer film.

10. An online visual detection instrument, characterized in that: The invention comprises a relationship curve between the Lab value obtained by the online monitoring method according to any one of claims 1 to 8 and the film thickness.

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