CN114559688B - Production process of durable photochromic PET (polyethylene terephthalate) film - Google Patents
Production process of durable photochromic PET (polyethylene terephthalate) film Download PDFInfo
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Abstract
A process for preparing durable photochromic PET film includes such steps as preparing WO 3 、TiO 2 Adding 8 concentration of composite sol with ZnO molecule ratio of 22:1:1-15:1:1% glycerol solution to form a photochromic liquid; the PET base film is conveyed into a soaking kettle, after vertical soaking, oblique soaking, liquid control and drying, an upper guide roller guides an upper film, a lower guide roller guides the PET base film and a lower film, and the PET base film, the upper photochromic layer, the PET base film, the lower photochromic layer and the lower film are pressed to form a film. The film formed in this way has uniform and excellent optical properties, avoids film-to-film peeling, and has better durability in use.
Description
Technical Field
The invention belongs to material science, and particularly relates to a production process of a durable photochromic PET film.
Background
With the continuous development of science and technology and the progress of human society, the demand of people for material materials is also continuously increased. Among various new materials, photochromic materials are favored by researchers because they can undergo reversible color changes under irradiation with excitation light. The method has huge application prospect in the fields of optical information storage, large-area data display, intelligent glass, military anti-counterfeiting and the like.
The photochromic phenomenon is that when the compound is irradiated by light with a certain wavelength, the compound is converted into a product with another color through a series of chemical reactions; the absorption spectrum of the material is obviously changed due to the change of the molecular structure or the electronic configuration of the material before and after the reaction, and the change is reflected as color change. The product after color change can generate reversible reaction to restore to the original state under the action of irradiation or heating of light with another wavelength. The photochromic polyester film is an important product of photochromic materials, and compared with a block material, the photochromic polyester film has the advantages of easy extensibility, low thickness and the like, and has some unique physical properties of force, sound, heat, electricity, light and the like, so the photochromic polyester film has great application advantages in the subdivision industry.
In the prior art, a three-layer film structure of a PET base film, a photochromic layer and a coated layer is generally formed by spraying or coating a photochromic liquid on a PET film and then performing film coating and pressing. However, the film with the structure has very high requirement on the flatness of the PET base film in the coating process, and the PET base film is not smooth enough on a production line due to air between the PET base film and a transmission roller and a transmission belt, so that the photochromic liquid is not uniform and even bubbles are generated in the coating process, and the effects of discoloration and fading after film forming are inconsistent.
Meanwhile, although the soaking mode can overcome the defects of the spraying and coating processes, in order to manufacture the three-layer film structure, photochromic liquid opposite to the base film needs to be cleaned after soaking is finished, an additional process is added, and the process is too complex.
Moreover, the three-layer film structure has higher requirement on the thickness of the photochromic layer, and the photochromic effect is influenced if the requirement is not met. In order to obtain a more pronounced color change effect, a thicker photochromic liquid needs to be applied, but this makes peeling between the film layers more likely.
Therefore, how to obtain a rapid preparation process with more obvious color change effect, more uniform color change performance and good film forming mechanical performance is an urgent problem to be solved.
In addition, the detection and verification of the photochromic performance of the film are indispensable important links in the film production, and the traditional method is to verify the photochromic performance of the film by a special instrument and measure whether the performance meets the performance requirement of the photochromic. The traditional measuring instruments comprise a spectrophotometer, a spectrometer, a scanning electron microscope, a transmission electron microscope, a diffractometer and the like, and the instruments have high measuring accuracy, but are usually expensive, high in specificity and relatively complex in operation, are usually used for sampling and detecting product samples, and are not suitable for large-scale production of factory production lines.
In the prior art, a means for carrying out rapid detection by using an image processing mode is also available, but the conventional image processing technology is not specially designed for the difficulty of film detection on a production line, is not suitable for a polyester film production line, is generally high in detection error rate and cannot be practically used in a factory.
Disclosure of Invention
To solve one or more of the above problems, and the problems mentioned in the examples, the following solutions are proposed.
A production process of a photochromic PET film capable of being used durably,
preparing photochromic liquid: mixing WO 3 、TiO 2 Adding a glycerol solution with the concentration of 8% into the composite sol with the ZnO molecular ratio of 22:1:1-15:1:1 to form photochromic liquid;
preparing a photochromic PET film by utilizing the photochromic liquid, the PET basal film and the laminating film:
(1) conveying the PET base film into a soaking kettle, and vertically soaking the PET base film for a soaking length L3;
(2) the vertically soaked PET base film is conveyed in the soaking kettle in an inclined upward direction through a turning roller, and the inclined soaking length is L1;
(3) after the PET base film is conveyed out of the liquid level in the inclined direction, the PET base film is continuously conveyed, and redundant liquid is removed in a controlled manner, wherein the liquid control length is L2;
(4) drying the PET base film by a drying device after the liquid control is finished, wherein the drying length is L4;
(5) after photochromic liquid can be firmly attached to the two sides of the PET base film, the upper guide roller guides the upper covering film, the lower guide roller guides the PET base film and the lower covering film, the three are pressed by the compression roller, and after pressing, the composite film is sent to the hot roller for hot pressing and finally becomes a film with the structure of upper covering film, upper photochromic layer, PET base film, lower photochromic layer and lower covering film;
wherein, perpendicular soaking length, slant soaking length, accuse liquid length, stoving length satisfy:
1.2*L3<L1<2.5*L3；
1.7*L1<L2<3.3*L1；
3.4*L1<L4<5.6*L1。
the method also comprises the step of detecting the optical property of the formed film.
A liquid level sensor is arranged in the soaking kettle and used for measuring the liquid level of the photochromic liquid, so that the distance of L3 is kept unchanged by adding or subtracting the photochromic liquid.
0.5m<L3<1m。
WO 3 、TiO 2 The ratio of ZnO molecules to ZnO molecules was 20:1: 1.
WO 3 、TiO 2 The ratio of ZnO molecules to ZnO molecules was 18:1: 1.
PET base film and lower tectorial membrane are at guide roller department coincidence down, and the PET base film is located the upside, and lower tectorial membrane is located the downside.
The drying adopts a mode of drying the upper side and the lower side simultaneously.
And during liquid control, the removed photochromic liquid flows into the soaking kettle.
The final film-forming structure is upper covering film, upper photochromic layer, PET basal film, lower photochromic layer and lower covering film.
The invention has the advantages that:
1. the photochromic liquid suitable for the soaking and adhering process is prepared, and particularly, the glycerol is added, and the proportion is optimized, so that the liquid can be matched with the soaking, liquid controlling and drying processes, and the PET film with good optical performance and difficult peeling is realized.
2. The film forming mode is optimized, and the soaking process is possible by adopting the film forming mode of upper film, photochromic layer, base film, photochromic layer and lower film. By soaking and attaching the photochromic liquid on two sides of the base film, a single-layer thin photochromic layer can be obtained, the peeling of the film layer is avoided, and meanwhile, the whole film forming optical performance is more excellent and the durability is better.
3. The length of the soaking region, the liquid control region and the drying region is optimized, so that the photochromic can be more uniformly and firmly attached to the base film, and the problem of non-uniform optical performance after film forming is avoided.
Drawings
FIG. 1 is a schematic view of an apparatus for manufacturing a photochromic film,
fig. 2 is a schematic view of a detection apparatus for photochromic films.
Detailed Description
Preparation of photochromic sol solution
Step 1: WO 3 Sol gelThe preparation of (1): adding Na into ultrapure water 2 WO 4 ·2H 2 O, stirring to dissolve, adding a mineral acid solution to acidify until the pH is =4 to obtain WO 3 And (3) solution. Adding oxalic acid into ultrapure water for dissolving, and heating and stirring in the dissolving process to obtain an oxalic acid solution. Heating at 45-63 deg.C, and stirring for 5-10 min. WO (International patent application) 3 Mixing the solution with oxalic acid solution, adding ultrapure water for dilution and stirring, standing for 6-10h to form colorless transparent WO 3 Sol, concentration 0.3M.
Step 2: TiO 2 2 Preparing sol: c is to be 16 H 36 O 4 Adding Ti (butyl titanate) into absolute ethyl alcohol, adding ultrapure water into the solution to perform polycondensation reaction, and preparing the TiO with sol concentration of 0.3M 2 And (3) sol.
And 3, step 3: preparation of ZnO Sol: will (CH) 3 COO) 2 Zn·2H 2 Dissolving O in absolute ethyl alcohol solution to form suspension, adding surfactant, and stirring at constant temperature to form ZnO sol with concentration of 0.3M.
And 4, step 4: mixing the three sols, and adding ultrapure water for dilution to obtain the photochromic composite sol with the concentration of 0.2M. Preferably, WO in the composite sol 3 、TiO 2 The molecular ratio of ZnO to ZnO is 22:1:1-15:1: 1. Preferably 20:1: 1. The above-mentioned ratio is an optimum value after a large number of experiments if TiO 2 When the ratio of ZnO to ZnO is too low, the response performance of photochromism is reduced, and when the ratio is too high, agglomeration occurs among sol particles, and the physical properties of the film are reduced when the film is subsequently coated on a high polymer film. And may hinder the next step of glycerol and WO 3 The contact of molecules reduces the optical properties after film formation. In one embodiment, WO 3 、TiO 2 The molecular ratio to ZnO can also be 18:1: 1.
And 5, step 5: and adding a glycerol solution into the composite sol liquid, ensuring that the mass of the glycerol added into each 10ml of the composite sol liquid is 0.3g, and mixing and stirring the solution to finally form the photochromic liquid for use. Preferably, the glycerol concentration is 5.6-8.5%, preferably 8%. Because the glycerol has stronger electricity pushingThe OH of the compound has the same valence as WO 3 、TiO 2 Fully contacts with ZnO molecules, and improves the optical performance. Meanwhile, the addition of the glycerol can improve the wettability of the sol, so that the sol is more uniform when in contact with the film, and the uniformity is improved. Furthermore, the proportion of the three sols and the proportion of the three sols to the glycerol are selected through a large number of experiments, so that the optimal light response performance and light fading performance can be achieved. Meanwhile, the proportion, particularly the addition of a proper amount of glycerol, ensures that the adhesiveness and the fluidity of the photochromic liquid are considered, thereby being more suitable for the following steps of soaking and controlling the liquid.
(II) preparation equipment of photochromic PET membrane
Comprises a soaking kettle J2, a drying device J4, an upper guide roller J8, a lower guide roller J7, a press roller J9, a hot-pressing roller J10, an upper steering roller J12 and a lower steering roller J11.
The photochromic liquid is arranged in the soaking kettle, the upper steering roller J12 is positioned on the edge of the input side of the soaking kettle, and the lower steering roller J11 is positioned in the soaking kettle and is positioned below the liquid level of the photochromic liquid. The two turning rollers ensure that the PET film J1 on the PET film is vertically immersed into the photochromic liquid by the turning rollers to a depth of L3.
The output side of the soaking kettle is provided with an upper guide roller J8 and a lower guide roller J7. The PET film obliquely spreads out from the soaking kettle after passing through the lower steering roller and is transferred to the lower guide roller. The upper guide roller is used for conveying the upper covering film J5, and the lower guide roller is used for conveying the soaked PET film and the lower covering film J6, so that the PET film is positioned between the upper covering film and the lower covering film.
A liquid level sensor J3 is arranged in the soaking kettle and used for measuring the liquid level of the photochromic liquid, so that the distance of L3 is ensured to be unchanged by adding or subtracting the photochromic liquid.
And a drying device J4 is arranged at the drying section between the soaking kettle and the guide roller and used for drying the PET film conveyed out of the soaking kettle. The drying adopts a mode of drying the upper side and the lower side simultaneously.
The compression roller 9 is arranged behind the two guide rollers and used for pressing the upper film, the PET base film and the lower film to form a composite film.
And the hot-pressing roller J10 is arranged behind the pressing roller and is used for further hot-pressing the laminated composite film to finally form a film.
In order to ensure that the photochromic liquid can be uniformly attached to the PET base film, a vertical soaking section (length L3) and an oblique soaking section (length L1) are provided. The vertical soaking section is from the position where the PET base film vertically enters the liquid to the position of the lower turning roll. The inclined soaking section is from a lower steering roller to a liquid outlet position of the PET base film. Thus, the problem of small adhesive force caused by single vertical soaking can be avoided. Meanwhile, the problem that subsequent redundant liquid is more and is difficult to clean due to horizontal soaking can be avoided. In order to remove the redundant photochromic liquid on the soaked PET film, a liquid control section (length L2) is formed from the position of the liquid outlet surface of the PET film to the drying starting point, and the liquid removed by the liquid control section flows into the soaking kettle. To increase the adhesion of the photochromic fluid, a baking section (length L4) is provided. In order to guarantee comprehensively that photochromic liquid can evenly adhere to, there is not residue and follow-up can with the high-efficient integration of tectorial membrane to realize better optical performance, avoid discolouring or the color inconsistency that appears in the discoloration process, and the bubble of tectorial membrane in-process, according to the characteristics of adhering to of PET membrane and photochromic liquid, through a large amount of experiments, the setting parameter is as follows:
1.2*L3<L1<2.5*L3；
1.7*L1<L2<3.3*L1；
3.4*L1<L4<5.6*L1；
as one preferred configuration for the photochromic liquid, L1=2 × L3, L2=2.5 × L1, L4=4 × L1, 0.5m < L3<1 m.
Therefore, the photochromic liquid can be firmly, uniformly and thinly attached to the base films on the two sides.
Preparation method of (III) photochromic PET film
In the prior art, a three-layer film structure of a PET base film, a photochromic layer and a coated layer is generally formed by spraying or coating a photochromic liquid on a PET film and then performing film coating and pressing. However, the film with the structure has very high requirement on the flatness of the PET base film in the coating process, and the PET base film is not smooth enough on a production line due to air between the PET base film and a transmission roller and a transmission belt, so that the photochromic liquid is not uniform and even bubbles are generated in the coating process, and the effects of discoloration and fading after film forming are inconsistent.
Meanwhile, although the soaking mode can overcome the defects of the spraying and coating processes, in order to manufacture the three-layer film structure, photochromic liquid opposite to the base film needs to be cleaned after soaking is finished, an additional process is added, and the process is too complex.
Moreover, the three-layer film structure has higher requirement on the thickness of the photochromic layer, and the photochromic effect is influenced if the thickness of the photochromic layer does not reach the standard. In order to obtain a more pronounced color change effect, a thicker photochromic liquid needs to be applied, but this makes peeling between the film layers more likely.
For this purpose, the invention proposes a five-layer structure composite film, namely a film-coated layer-thin photochromic layer-PET-based film-thin photochromic layer-film-coated layer. Therefore, the thickness of a single photochromic layer can be reduced, interlayer stripping is avoided, the using amount of photochromic substances is integrally increased, and a more obvious photochromic effect is obtained. More importantly, the soaking process can be skillfully used, so that the waste and the trouble in treatment of the redundant photochromic liquid are avoided, and the problem of high requirement on the flatness of the base film by the coating and spraying process is solved. The preparation method comprises the following steps:
(1) and (3) conveying the PET base film into a soaking kettle, and vertically entering the soaking kettle to realize vertical soaking, wherein the soaking length is L3.
(2) The PET base film which is vertically soaked is conveyed upwards in the soaking kettle in an inclined way through a turning roller, and the inclined soaking length is L1.
(3) And after the PET base film is conveyed out of the liquid level in the inclined upward direction, the PET base film is continuously conveyed in the inclined upward direction, and the residual redundant liquid on the surface of the base film is drained. The length of the control liquid is L2.
(4) And after the liquid control is finished, the PET base film is continuously conveyed and is dried by a drying device, and the drying length is L4.
(5) After the photochromic liquid can be firmly attached to the two sides of the PET base film, the upper covering film and the lower covering film are pressed through a compression roller, the composite film is sent to a hot roller for hot pressing after the pressing is finished, and finally a film with the structure of upper covering film, upper photochromic layer, PET base film, lower photochromic layer and lower covering film is formed.
By controlling the component proportion of the photochromic liquid, the vertical soaking, the oblique soaking, the liquid control length and the drying length, the thickness of the photochromic layer is 1/3-2/3 of the conventional thickness, but the photochromic effect is improved by 27-43 percent compared with the conventional photochromic film, and the interlayer peeling probability is reduced by 14 percent.
(IV) optical performance online detection equipment and method
1. Detection device
The detection zone includes a detection conveyor belt B4, an illumination source B1 located on the upper side of the detection conveyor belt, a discoloration detection camera B2, and a discoloration detection camera B3 located on the lower side of the detection conveyor belt.
Wherein the cut photochromic polyester film B5 is positioned on a conveyor belt. Preferably, the conveyer belt sets up static generating device, can make the conveyer belt carry static to make the film can be smooth adsorb on the conveyer belt, improve and detect the precision.
The illumination source is located the conveyer belt upside, can set up illumination source quantity according to conveyer belt speed, illumination time.
The color-changing detection camera is positioned on the upper side of the conveyor belt and at the tail end of the conveyor belt for collecting color-changing images of the thin film which are transmitted to the tail end after the illumination is finished.
The fading detection camera is positioned at the lower side of the conveyor belt, positioned at the initial end of the conveyor belt and used for collecting a film fading image after the fading is finished.
The film is absorbed by the conveyor belt, rotates from the initial end to the upper side, receives illumination and changes color, rotates to the lower side of the conveyor belt after the color-changing image collection is finished, and performs light fading for a certain time to receive the light fading image collection. After finishing, the process can be transmitted to the next step of the production line.
2. Photochromic polyester film color changing and fading detection process
Controlling the color change and color fading of the photochromic film and corresponding automatic detection by using a controllable automatic uniform-speed conveyor belt device, mounting the film to be detected on the conveyor belt, mounting an illumination source for exciting the color change of the film above one side of the conveyor belt, and mounting cameras for detecting the color change condition of the film at two ends of the conveyor belt; when the film moves along with the conveyor belt, the film on one side of the illumination source is excited to change color by continuous illumination of the illumination source; a camera at one end of the conveyor belt shoots a film image which is illuminated for a certain time, and judges whether the film changes color as expected according to an intelligent algorithm; the film rotates to the other side along with the conveyor belt and is not irradiated by the light source any more, so the film fades to the basic color; and a camera at the other end of the conveyor belt shoots the faded film image, and judges whether the film fades as expected or not according to an intelligent algorithm.
The conveying belt device is used for fixing the film to be measured and can move at a constant speed, so that the film can be uniformly illuminated; the length of the conveyor belt and the constant rotating speed are determined according to the excitation time and the fading time required by the photochromic polyester film, and the larger value of the length of the conveyor belt and the constant rotating speed is taken to determine the ratio of the length of the conveyor belt to the rotating speed; the absolute value of the length of the conveyor belt is determined depending on the amount of film material and the installation site space.
The illumination source is arranged above one side of the conveyor belt and used for exciting the color of the film to change and enabling the other side of the conveyor belt not to be illuminated so as to enable the film to have a color fading condition; and installing proper quantity of light sources to keep the light for a certain time according to the continuous irradiation time and the rotation speed of the conveyor belt.
The cameras are arranged on two sides of two ends of the conveyor belt and are respectively used for detecting the color change and fading of the film; the camera takes images at a frame rate that is set to an appropriate value depending on the rotational speed of the conveyor belt and performs automatic detection.
Before the automatic detection starts, an illumination source is arranged on one side of the conveyor belt, and the illumination source covers the length of the conveyor belt
An appropriate number of illumination sources are arranged,
，
indicating the linear speed of rotation of the conveyor belt,
indicating the minimum excitation time required for the film to discolor.
Minimum time required for film discoloration
Calculating length from linear speed of rotation of conveyor belt
. Actual installed length of conveyor belt
Take the large values of both:
and meets the space requirement of the installation site. If the space of the installation site is small, the linear speed of the rotation of the conveyor belt can be properly reduced
And ensuring that the film can obtain sufficient reaction time in a small space.
A detection step:
(1) installing a film to be detected on the side, which is not illuminated by light, of the conveyor belt, and aligning the film to be detected with the initial end of the conveyor belt; the starting end refers to the starting end of the conveyor belt on the side receiving light and depending on the rotating direction, and the opposite end is called the tail end.
Two cameras are respectively arranged at the beginning end and the tail end of the conveyor belt. And starting the illumination source, starting the camera, and keeping the clock of the camera and the rotating clock of the conveyor belt synchronous.
(2) Starting the conveyor belt, and rotating the conveyor belt; the film is brought to the side irradiated by the light from the upper side by the conveyor belt, and is transmitted at a constant speed, and the film is irradiated by the light source. After the irradiation is finished, the film is conveyed to the tail end by the conveying belt, and the tail end is subjected to color change image acquisition after being irradiated by the color change detection camera.
During rotation of the belt, the two cameras are at frame rate
An image is captured. Frame rate
The film that can guarantee that the camera is complete to shoot along with the conveyer belt rotation. Suppose that the camera can photograph a field of view having a distance of
Then should be
。
(3) After the film rotates on the conveying belt through the tail end, the film rotates to the side, which is not irradiated by light, of the lower side, and the light-withdrawing operation is started.
(4) After the conveyor belt rotates for a circle, the film returns to the initial position; at this time, the fading detection camera collects the fading image of the film.
(5) Sending the image to a server, identifying and detecting by using the following method and/or model, determining whether the color-changing performance and the fading performance meet the requirements, and marking the regions which do not meet the requirements.
The illumination source is turned off. The conveyor belt continues to rotate for half a revolution and stops. Both cameras are turned off.
Further, if the intention is to examine the optical response properties of the film when repeatedly subjected to the light irradiation condition and the light extraction condition. The operation of the above steps (1) to (4) may be continued without stopping after the conveyor belt completes one rotation. The number and frequency of cycles is determined by the detection requirements.
After the steps are completed, the two cameras respectively shoot a plurality of images, follow-up steps are adopted to process the images, and the performance verification of the photochromic polyester film is further implemented. Therefore, the method can be applied to a production line to detect one film and accurately judge the part of the film which does not meet the requirements of color change and fading.
It is noted here that since the method is used on a production line, two cameras are continuously photographed. The performance of each part of the polyester film on the production line can be detected without stopping the production line.
3. Detection algorithm of photochromic polyester film
Step 1: and collecting a color-changing image and a fading image. See the above procedure for details.
Step 2: image-based photochromic polyester film detection and localization
And (3) detecting the coverage range and the position of the photochromic polyester film in the image from the image obtained in the step (1), and outputting corresponding coordinates.
It is known that the spectral distributions of the photochromic polyester film after discoloration and after discoloration are similar to each other, and the color tone distribution of the film in an image is expressed. Assuming that a digital Image is acquired, which has three channels of RGB (red, green and blue), it is first transformed into HIS (hue, saturation, brightness) space, making its color hue components independent. Defining:
Pre-selecting a plurality of sample images of polyester film, all sample images forming a set
Including two types of images of photochromic polyester film after color change and after color fading
And
，
and separately calculate each image
Color tone channel of
Calculating the average value of the faded color tones according to the image classification
And average value of color tone after color change
。
Let x and y denote the spatial coordinates of a single pixel of a channel in the image, then
Representing images
Is x, y coordinates in the hue channel H. Let the pixel value range be [0, 1 ]]And divided into 256 gray levels.
For an image
Definition set
：
Indicating the color-changed image
Wherein all hue values satisfy the set of pixel coordinates of equation (4).
In the above-mentioned two formulas, the first and second formulas,
、
indicating a predefined empirical threshold, taken as preferred
5。
And (3) comparing the new unknown image with the known sample image, and acquiring the pixel coordinates of the image with the color tone similar to that of the sample image according to the formulas (3) and (4), so as to approximately obtain the position of the polyester film in one unknown image and infer the color change state of the film.
Step 3, distinguishing model and distinguishing method for color changing state of polyester film based on pixels
Training a discrimination model according to the sample image and the pixel coordinates meeting the conditions in the sample image in the step 2, and identifying whether the image comprises a polyester film or not and the color change and fading states of the polyester film; after the model training is finished, the image to be detected is input into the model, and the model automatically outputs the judgment result of the input image, namely whether the image contains the polyester film or not and the color changing and fading states of the polyester film.
Before training, a plurality of sample images comprising faded and discolored polyester films are prepared, and the sample image set in the step 2 can be used
. And several sample images were prepared separately without the polyester film.
For an image
Defining a two-dimensional matrix corresponding thereto
、
：
In a clear view of the above, it is known that,
、
in a two-dimensional matrix corresponding to the size of the Image space of the original Image, if the color tone of a pixel at a certain position in the original Image is close to that of the faded sample (equation (3) is satisfied), the two-dimensional matrix is used as a color tone correction matrix
Otherwise
；
The same is true. The M, N matrix is adopted to simplify the calculation process and improve the calculation efficiency and accuracy.
Further, defining:
in the formula (7), the reaction mixture is,
representing a convolution operation, the convolution windows are all 31, namely:
in the formula (9), the reaction mixture is,
expressing the convergence speed parameter of the excitation function, controlling the convergence speed of the excitation function, having a certain influence on the model performance, and taking the parameter as an optimal value
.
The convolution window defined by equation (7) is used to extract low-scale spatial distribution features in the image, describing the local pixel distribution of the image, which is correlated with the sample image and can be used to identify the color change state of the mylar.
Further, defining:
in the formula (I), the compound is shown in the specification,
representing taking the maximum value of the window, p, q representing the maximum value in the windowAnd taking an integer.
Is a bias variable.
、
Represents the matrix in the above formula (7)
、
The value of the corresponding coordinate.
The above equation is used to downsample the input matrix.
Further, defining:
in the formula (I), the compound is shown in the specification,
representation and matrix
、
Middle coordinate
The corresponding linear weight is given to the corresponding linear weight,
、
the value of the matrix corresponding coordinate in expression (10),
is a bias variable.
The excitation function defined for equation (9).
The above formula is used for extracting the spatial distribution characteristic of the input matrix after down-sampling, i.e. the high-scale spatial distribution characteristic of the image, describing the overall pixel distribution of the image, and is also used for identifying the color change state of the polyester film.
Further, defining:
in the formula (I), the compound is shown in the specification,
、
respectively represent and matrix
Corresponding to the linear weight at the coordinate(s),
the value of the coordinate corresponding to the matrix E in expression (11) is expressed.
Equation (12) relates the aforementioned modeled image features to the state variables to be recognized, respectively.
Is a binary vector of elements
，
. When in use
When the Image of the input Image contains a polyester film, the Image is displayed on a display unit
When the Image is a faded polyester film, the Image is represented by
When the Image is included, the color-changed polyester film is included in the Image; otherwise, when
In the case where the Image does not include the discolored polyester film, the discolored polyester film is not included.
Equations (5) - (12) jointly define a discrimination model for the color change state of the pixel-based mylar film. Wherein, the formulas (5) and (6) are defined
、
Is the input of the model, defined by equation (12)
And outputting the model. The model training method is as follows.
As mentioned above, several image samples are prepared, and the matrix corresponding to each image sample is obtained according to the formulas (5) and (6) and defined in step 2
、
。
The parameters of the models (7) - (12) are assigned initial values, wherein the linear weight can be assigned to 1 and the bias variable can be assigned to 0.
According to models (7) - (12), input
、
Computing corresponding outputs
。
Assigning a set of truth values to each sample based on whether the sample image contains a polyester film and the corresponding color change status
Calculating the difference value between the model output value and the true value:
and calculating according to (13) iterative calculation by using back propagation algorithm
Minimum value of (c). In the formula
、
To control the parameters, satisfy
Appropriately adjusted according to the sample data
、
Is helpful to improve the performance of the model. Accordingly, preferred values can be taken
,
.
When the temperature is higher than the set temperature
After the minimum value is reached, corresponding iteration parameters such as linear weight, bias variable and the like are used as the optimal solution of the model. And finishing the model training.
And (3) giving a test image to be distinguished, obtaining corresponding model input according to the formulas (5) and (6) and the definition in the step (2), inputting the model, and obtaining an output value.
If output
And is and
if so, determining that the test image comprises the discolored polyester film; if output
And is and
if so, determining that the test image comprises the faded polyester film; otherwise if it is not
The polyester film is not included in the test image.
Through the specific algorithm design and the setting of the excitation function and the cost function, the method can be suitable for a polyester film production line, and the color-changing performance and the light-fading performance can be accurately judged.
Step 4 model-based performance verification of photochromic polyester film
And (3) after the detection process is carried out, the conveyor belt rotates at a constant speed, the camera shoots images at a certain frame rate, corresponding judgment output values of the images are calculated according to the methods in the steps (2) and (3), and the shot time stamps and the judgment output values are stored in a correlation mode so as to implement performance verification.
And positioning the film to be detected at the position where the specific time stamp corresponds to and flows through the camera according to the rotating speed and the passing time stamp of the conveying belt. Setting the length of the film to be detected as
Length of conveyor belt
Linear speed of rotation of the belt
. The time stamp reference zero point is set when the conveyor belt starts to rotate. Then pass through
When the film is changed in color, the initial end of the film passes through the film color change detection camera and then passes through
When the film is in use, the tail end of the film leaves the film discoloration detection camera. In that
And meanwhile, if the area of the polyester film which does not comprise the color change is judged by the model, recording that the performance of the area does not reach the standard, and simultaneously recording the corresponding image and the corresponding timestamp. Through
When the film fades, the initial end of the film passes through the film fading detection camera and then passes through
The end of the film is moved away from the film fade detection camera. In that
During the period, if the film is fadedAnd judging the area of the polyester film, which does not comprise the faded image (i.e. faded image), of the image shot by the detection camera through the model, wherein the recording performance of the area does not reach the standard, and simultaneously recording the corresponding image and the corresponding timestamp.
The test specimens were manually inspected using a high-precision spectrophotometer and compared to the automated validation methods described herein, with the results of comparison being seen in the table below. The contrast test sample comprises 700 parts (corresponding to images comprising 700 pieces of polyester film), wherein the polyester film sample which reaches the standard after color change and the image thereof are 300 parts, the polyester film sample which reaches the standard after color change and the image thereof are 200 parts, and the polyester film sample which reaches the standard after color change and the polyester film sample which does not reach the standard after color change and the image thereof are 100 parts respectively. According to the comparative test results, the detection accuracy is (287+192+94+91)/700 × 100% = 94.9%.
It can be seen that the method herein verifies that the accuracy is within the acceptable range as shown in the following table compared to the classical manual fit of various equipment methods, but the time duration used is greatly reduced (the time duration is reduced by more than 95%). More importantly, due to the extremely high efficiency, the method can be used for carrying out online quick inspection on all products and is applied to the continuous detection of large-scale polyester film products without adopting a manual spot inspection mode. Considering the error of spot check, the actual accuracy is higher than that of manual work.
The above is merely a preferred example, and it can be understood that the film preparation process and the on-line detection method of the present invention can be applied to a photochromic liquid prepared from any components, but the components of the photochromic liquid of the present invention are optimally matched with the film preparation process.
It will be appreciated by those skilled in the art that while a number of exemplary embodiments of the invention have been shown and described in detail herein, many other variations or modifications can be made, which are consistent with the principles of this invention, and which are directly determined or derived from the disclosure herein, without departing from the spirit and scope of the invention. Accordingly, the scope of the invention should be understood and interpreted to cover all such other variations or modifications.
Claims (9)
1. A production process of a photochromic PET film capable of being used durably is characterized in that:
preparing photochromic liquid: mixing WO 3 、TiO 2 Adding a glycerol solution with the concentration of 8% into the composite sol with the ZnO molecular ratio of 22:1:1-15:1:1 to form photochromic liquid;
preparing a photochromic PET film by utilizing the photochromic liquid, the PET basal film and the laminating film:
(1) conveying the PET base film into a soaking kettle, and vertically soaking the PET base film for a soaking length L3;
(2) the vertically soaked PET base film is conveyed in the soaking kettle in an inclined upward direction through a turning roller, and the inclined soaking length is L1;
(3) after the PET base film is conveyed out of the liquid level in the inclined direction, the PET base film is continuously conveyed, and redundant liquid is removed in a controlled manner, wherein the liquid control length is L2;
(4) drying the PET base film by a drying device after the liquid control is finished, wherein the drying length is L4;
(5) after photochromic liquid can be firmly attached to the two sides of the PET base film, the upper guide roller guides the upper covering film, the lower guide roller guides the PET base film and the lower covering film, the three are pressed by the compression roller, and after pressing, the composite film is sent to the hot roller for hot pressing and finally becomes a film with the structure of upper covering film, upper photochromic layer, PET base film, lower photochromic layer and lower covering film;
wherein, perpendicular soaking length, slant soaking length, accuse liquid length, stoving length satisfy:
1.2*L3<L1<2.5*L3；
1.7*L1<L2<3.3*L1；
3.4*L1<L4<5.6*L1。
the method also comprises the step of carrying out optical property detection on the formed film, wherein the optical property detection comprises the following steps:
installing a film to be detected on a conveyor belt, installing an illumination source for exciting the color change of the film above one side of the conveyor belt, and installing a film color change detection camera and a film fading detection camera for detecting the color change condition of the film at two ends of the conveyor belt; when the formed film moves along with the conveyor belt, the formed film on one side of the illumination source is excited to change color by continuous illumination of the illumination source; a film discoloration detection camera at one end of the conveyor belt shoots an illuminated film forming image, and judges whether the film forming changes color as expected according to an intelligent algorithm; the formed film rotates to the other side along with the conveyor belt, is not irradiated by the light source any more, and begins to fade; a film fading detection camera at the other end of the conveyor belt shoots a film forming image after fading, and judges whether the film fades as expected according to an intelligent algorithm;
the intelligent algorithm comprises a discriminant model with an excitation function in the following form:
setting the length of the film to be detected as
Length of conveyor belt
Linear speed of rotation of the belt
(ii) a When the conveyor belt starts to rotate, the conveyor belt passes through the zero point
When the film is in use, the initial end of the film passes through the film color change detection camera and then passes through
When the film is in use, the tail end of the film leaves the film color change detection camera; in that
Meanwhile, if the image shot by the film color-changing detection camera does not comprise the polyester film area after color changing through model discrimination, recording that the performance of the area does not reach the standard; through a process
When the film is faded, the initial end of the film passes through the film fading detection camera and the film fading detection camera
While the end of the film is away from the film fade detection camera; in that
Meanwhile, if the image shot by the film fading detection camera does not include the faded polyester film area through model discrimination, the recording performance of the area does not reach the standard.
2. The production process according to claim 1, wherein: a liquid level sensor is arranged in the soaking kettle and used for measuring the liquid level of the photochromic liquid, so that the distance of L3 is kept unchanged by adding or subtracting the photochromic liquid.
3. The production process according to claim 1, wherein: 0.5m < L3<1 m.
4. The production process according to claim 1, wherein: WO 3 、TiO 2 The ratio of ZnO molecules to ZnO molecules was 20:1: 1.
5. The production process according to claim 1, wherein: WO 3 、TiO 2 The ratio of ZnO molecules to ZnO molecules was 18:1: 1.
6. The production process according to claim 1, wherein: PET base film and lower tectorial membrane are at guide roller department coincidence down, and the PET base film is located the upside, and lower tectorial membrane is located the downside.
7. The production process according to claim 1, wherein: the drying adopts a mode of simultaneously drying the upper side and the lower side.
8. The production process according to claim 1, wherein: and during liquid control, the removed photochromic liquid flows into the soaking kettle.
9. The production process according to claim 1, wherein: the final film-forming structure is upper covering film, upper photochromic layer, PET basal film, lower photochromic layer and lower covering film.
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| JP2004109582A (en) * | 2002-09-19 | 2004-04-08 | Dainippon Printing Co Ltd | Dimmer laminate body |
| CN101006123A (en) * | 2005-09-06 | 2007-07-25 | Lg化学株式会社 | Method for the preparation of photochromic film or plate |
| CN102219987A (en) * | 2011-06-01 | 2011-10-19 | 天津大学 | Photochromic polyethylene terephthalate mixed film and preparation method thereof |
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| US6773108B2 (en) * | 2001-03-21 | 2004-08-10 | Invicta Corporation | Lens with photochromic elastomer film and method of making it |
| US20070259117A1 (en) * | 2006-05-04 | 2007-11-08 | Bayer Materialscience Llc | Article having photochromic properties and process for its manufacture |
| CN103009634B (en) * | 2011-09-26 | 2015-02-18 | 蓝星(北京)化工机械有限公司 | Thermoplastic resin composite material and preparation method thereof |
| CN105015140A (en) * | 2015-08-06 | 2015-11-04 | 青岛天和清原科技有限公司 | Degradable non-woven fabric glue dipping composite preparation technology and materials thereof |
| CN110239170A (en) * | 2018-03-06 | 2019-09-17 | 齐凌科技有限公司 | A kind of mask |
| TW202136470A (en) * | 2020-02-27 | 2021-10-01 | 日商德山股份有限公司 | Photochromic optical article |
| CN111391445A (en) * | 2020-04-07 | 2020-07-10 | 西北工业大学 | Photochromic film and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JP2004109582A (en) * | 2002-09-19 | 2004-04-08 | Dainippon Printing Co Ltd | Dimmer laminate body |
| CN101006123A (en) * | 2005-09-06 | 2007-07-25 | Lg化学株式会社 | Method for the preparation of photochromic film or plate |
| CN102219987A (en) * | 2011-06-01 | 2011-10-19 | 天津大学 | Photochromic polyethylene terephthalate mixed film and preparation method thereof |
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