Process for quantitative image analysis of liquid leakage from barrier coatings

Abstract

A method for quantifying liquid leakage from a barrier coating includes: a) providing a system for acquiring and analyzing images of a wet substrate; b) loading the wet substrate into a holder; c) illuminating the wet substrate using an illumination system; d) acquiring at least one image of the wet substrate using an imaging system; e) using an analysis unit to transform at least one image of the wet substrate to provide at least one transformed image, and quantifying liquid leakage from the barrier coating based on the at least one transformed image; and f) providing an output including a value that identifies the amount or percentage of liquid on the wet substrate, and / or a generated image showing the amount or percentage of liquid on the wet substrate.

Description

Technical Field

[0001] The present invention generally relates to a process for identifying and quantifying liquid leakage of a barrier coating using image analysis.

Background Art

[0002] Barrier coatings are important commodities used to protect food, products, and other materials. Examples of barrier coatings for paper substrates include, for example, pulp treatment with fluorocarbons, extrusion polyethylene coatings, and waterborne coatings. Sustainability goals are driving the industry towards thinner solvent-free coatings. However, meeting sustainability goals without sacrificing coating performance remains a challenge.

[0003] Evaluating the performance of these coatings is necessary to determine whether the coating functions properly. The performance of barrier coatings is one of the most important performance evaluation metrics used by consumers and researchers. For example, liquid resistance such as water resistance, oil resistance, and grease resistance are important performance criteria in the food and packaging industries.

[0004] For example, grease leakage from paper coatings is typically observed or measured by humans. Identifying and quantifying grease leakage is often difficult to accurately, reproducibly, and / or quickly quantify because the process takes a significant amount of time.

[0005] There is a need for a process that can more accurately and reproducibly detect liquid leakage of a barrier coating to identify and quantify the performance of the barrier coating.

Summary of the Invention

[0006] The present invention is a method for quantifying liquid leakage of a barrier coating, comprising a) a system for acquiring and analyzing an image, i) An imaging system for acquiring one or more images of a wet substrate, ii) A lighting system including at least one light source for illuminating a wet substrate, iii) A holder for holding a wet substrate in a position illuminated by at least one light source, iv) To provide a system comprising an analysis unit configured to transform one or more images and quantitatively analyze one or more transformed images for oil leakage from a barrier coating, b) Loading a wet substrate containing oil or grease into the holder, c) Illuminating a wet substrate using a lighting system, d) Acquire at least one image of the wet substrate using an imaging system, e) Transforming at least one image of a wet substrate using an analysis unit, wherein the transformation of at least one image of the wet substrate includes processing the at least one image of the wet substrate using an algorithm selected from the group consisting of image thresholding, wavelet transform, morphological transformation, color detection, pattern detection, clustering, and combinations thereof to provide at least one transformed image, and quantifying the oil leakage of the barrier coating based on the at least one transformed image. f) A method comprising providing an output which includes a value that identifies the amount or percentage of oil or grease on a wet substrate, and / or a generated image showing the amount or percentage of oil or grease on a wet substrate. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic diagram of a system for acquiring and analyzing images according to an embodiment of the present invention. [Figure 2] This is a schematic diagram of the position of the light source relative to the wet substrate according to an embodiment of the present invention. [Figure 3] These are a series of images showing the transformation of images analyzed by the image analysis system according to an embodiment of the present invention. [Figure 4]This is a parity plot comparing the fat leakage rate counted by the observer with the fat leakage rate quantified by the process according to one embodiment of the present invention. [Figure 5A] These are the acquired image and the converted image, respectively, of a wet substrate analyzed by the image analysis system according to an embodiment of the present invention. [Figure 5B] These are the acquired image and the converted image, respectively, of a wet substrate analyzed by the image analysis system according to an embodiment of the present invention. [Modes for carrying out the invention]

[0008] The inventors have found a process for reproducibly and accurately identifying and quantifying liquid leakage from barrier coatings.

[0009] As used herein, the term “barrier coating” refers to a film or coating designed to prevent the passage of liquids, such as oil or grease. Preferably, the barrier coating is formed on a substrate, such as paper or cardboard. Such barrier coatings are known in the art and are commonly used to protect food or products. The barrier coating may include commercially available coatings.

[0010] As used herein, the term “wet substrate” refers to a substrate that has come into contact with a liquid, for example, water, or is contaminated with oil or grease. For example, a wet substrate may include an absorbent material such as paper, or any other material in which a liquid penetrating the barrier coating can be observed. The substrate may include metal, plastic, wood, glass, composites, fiberglass, paper, fabric, leather, or other substrates. For testing purposes, it is preferable that the substrate has a flat or planar surface.

[0011] As used herein, the term “leakage” refers to the passage of a liquid through a barrier coating. For example, a barrier coating designed to prevent the penetration of water may be tested for water leakage. Similarly, a barrier coating designed to prevent the penetration of oil or grease may be tested for grease leakage. Any combination of liquid and barrier coating can be analyzed by the process of the present invention to detect liquid leakage. The analysis is similar for each combination of liquid and barrier coating.

[0012] In one embodiment, a barrier coating is tested for grease leakage. Grease leakage is a measure of the barrier coating's resistance to grease or oil. To test for grease leakage, the barrier coating is typically placed on a substrate that absorbs or exhibits oil or grease penetrating the barrier coating. Oil or grease is placed on the barrier coating, and after a predetermined time has elapsed, the substrate is observed to determine whether the oil and grease have penetrated the barrier coating, and if so, how much oil or grease has penetrated the barrier coating. The oil or grease may be applied directly to the surface of the barrier coating, or it may be applied to a pad or other article placed on top of the barrier coating. A weight may be placed on top of the oil or grease to apply pressure and accelerate the testing process.

[0013] A system is provided for analyzing and quantifying oil leakage in barrier coatings to analyze liquid leakage. A schematic diagram of the system 100 for analyzing and quantifying defects is shown in Figure 1. The system 100 comprises an imaging system 10, an illumination system 20, a holder 30 for holding a wet substrate 35, and an analysis unit 40.

[0014] The imaging system 10 is configured to acquire one or more images of the wet substrate 35. The imaging system 10 may also be configured to acquire images of multiple channels, each of which contains wavelengths within a predetermined range. For example, each channel may consist of wavelengths associated with a single color of light in the visible spectrum (e.g., red = 620-780 nm, orange = 585-620 nm, etc.). Alternatively, each channel may consist of wavelengths within a predetermined range (e.g., channel 1 = 400-500 nm, channel 2 = 500-600 nm, etc.). In yet another embodiment, one channel may contain the visible light spectrum and the second channel may contain either the ultraviolet spectrum or the infrared spectrum. In yet another embodiment, one channel may contain wavelengths in the near-infrared range (800-1000 nm) and the second channel may contain longer infrared wavelengths (e.g., 1000-1500 nm).

[0015] To identify and quantify liquid leakage, the imaging system may be configured to acquire images in the channel most relevant to the color of the defect. For example, when analyzing a wet substrate using a liquid that has a different color from the substrate, the imaging system 10 may be configured to acquire at least one image in a channel containing wavelengths relevant to the color of the liquid. A second channel may be used as a reference. If the liquid absorbs or reflects ultraviolet or infrared light differently from the substrate, the imaging system 10 may be configured to acquire at least one image in the ultraviolet and / or infrared spectrum.

[0016] The imaging system 10 may include, for example, a camera, a thermal imaging system, an ultraviolet imaging system, or an image sensor. The imaging system 10 may further include filters for preferentially or selectively transmitting or blocking light of a predetermined wavelength, such as at least one channel of a predetermined wavelength. For example, if the imaging system 10 is configured to detect in the ultraviolet spectrum, a filter can be used to block a channel of visible light. For example, if the infrared spectrum is used, a filter can be used to block visible wavelengths and allow transmission of infrared wavelengths.

[0017] The illumination system 20 includes at least one light source for illuminating the wet substrate 35. The illumination system 20 may be configured to emit radiation in the visible light spectrum, infrared spectrum, ultraviolet spectrum, and combinations thereof. Preferably, the illumination system is configured to emit radiation of wavelengths related to at least one of the multiple channels used by the imaging system 10. The at least one light source may include a single light source or multiple light sources. If a single light source is used, the light source may include a ring light or a diffuser to provide uniform illumination to the wet substrate 35. If multiple light sources are used, the light sources may be arranged to provide uniform illumination. The multiple light sources may also be controlled individually or within a predetermined group to control the illumination of the wet substrate 35. Preferably, the illumination system 20 is configured to allow adjustment of the light intensity, the angle of incidence to the wet substrate 35, or the wavelength of the emitted light.

[0018] The substrate holder 30 is used to hold the wet substrate 35 for imaging by the imaging system 10. The holder 30 is configured to hold the wet substrate in a position where it is illuminated by the illumination system 20 when the wet substrate is imaged. The holder 30 may be configured to hold a single wet substrate 35 or multiple wet substrates. The holder 30 may be stationary or may be adapted to allow automatic loading and unloading of test specimens.

[0019] Preferably, at least one of the imaging system 10 and the holder 30 is adjustable such that the position of the wet substrate 35 can be changed with respect to the imaging system 10. For example, as shown in FIG. 1, the imaging system 10 may be mounted on an arm 101 attached to a vertical support 102. The arm 101 may be configured to be adjustable so as to be able to select the distance between the imaging system 10 and the holder 30. Alternatively, the arm 101 may be movable between two or more positions. In another alternative, the holder 30 may be adjustable to raise or lower the holder 30 using a base 103, or the angle of the holder with respect to a fixed position may be adjusted.

[0020] Preferably, at least one of the illumination system 20 and the holder 30 is adjustable relative to each other such that the position of the wet substrate 35 can be changed with respect to the illumination system 20. For example, as shown in FIG. 2, the illumination system 20 may be adjustable in height or angle with respect to the holder 30 to change the incident angle α of the light 25. For example, the illumination system 20 may be adjustable to allow a shallower or steeper incident angle to the wet substrate 35. Further, the illumination system 20 may be adjustable to allow rotation of the illumination system 20 around the wet substrate 35 such that the incident angle α is the same but the light is directed at the wet substrate 35 from a different angle, for example, from the side rather than the front of the wet substrate 35. To reduce the potential influence of external illumination, the system 100 may be covered or surrounded such that only the light from the illumination system 20 is used to acquire an image (not shown).

[0021] System 100 further includes an analysis unit 40 configured to convert an image acquired by imaging system 10 into a converted image. Analysis unit 40 further quantitatively analyzes the converted image to identify and / or quantify the amount or rate of liquid leakage of the barrier coating as indicated by the amount or rate of liquid on wet substrate 35. Analysis unit 40 may comprise, for example, a computer, a workstation, a notebook computer, a tablet computer, or a smartphone. Analysis unit 40 may comprise an application or program adapted to convert and analyze images from imaging system 10. Information acquired and / or generated by system 100 may be stored locally within analysis unit 40, a server, cloud storage, or a media storage device.

[0022] Analysis unit 40 is preferably configured to convert the acquired image by processing the acquired image using an algorithm selected from image thresholding, wavelet transform, morphological transform, color detection, pattern detection, contrast detection, clustering, and combinations thereof. The converted image is then analyzed by analysis unit 40 to identify and / or quantify the liquid on wet substrate 35 and provide an output of the analysis. Preferably, the output includes a value representing the amount / rate of liquid leakage and / or an image or dataset identifying the location, size, and / or amount / rate of the liquid leakage.

[0023] Preferably, analysis unit 40 includes or is connected to a display including a graphical user interface (GUI). The GUI is preferably configured to display the output of analysis unit 40. For example, the GUI may display a value quantifying the amount or rate of liquid present on wet substrate 35. Alternatively, the GUI may display a converted image identifying the location, size, and / or amount / rate of the wet region on the wet substrate.

[0024] A method for identifying and quantifying liquid leakage from a barrier coating according to the present invention includes providing a system for acquiring and analyzing images; loading a wet substrate into a holder; illuminating the wet substrate using an illumination system; acquiring at least one image of the wet substrate using an imaging system; transforming at least one image of the wet substrate using an analysis unit to provide at least one transformed image; identifying and quantifying oil or liquid on the wet substrate based on at least one transformed image; and providing an output. Preferably, the liquid is selected from water or oil / grease.

[0025] In one embodiment, the analysis is configured to identify leakage areas by processing the acquired images by transforming them through morphological transformation. The transformation of the acquired images may further include increasing the contrast level of the images, transforming or straightening the perspective of the images, reducing noise in the images, and combinations thereof. [Examples]

[0026] A system with a configuration similar to that shown in Figure 1 was prepared using a camera as an imaging system, an illumination system for illuminating the substrate with white light, and a customizable sample holder for holding the wet substrate for imaging and analysis.

[0027] Next, all or a subset of the acquired images were transformed using an image analysis algorithm. The image analysis algorithm identified and quantified the amount or proportion of liquid on the wet substrate.

[0028] Oil resistance test Barrier-coated paper substrates were subjected to oil and grease resistance tests. A 1-inch diameter cloth soaked in oil was placed on the barrier-coated paper substrate, and then placed on a sheet of graph paper on a glass surface. A 50g brass weight was placed on the cloth and left for a predetermined time. The graph paper was then removed and analyzed by a tester using the system according to this method. The tester was able to provide a subjective quantification of the area affected by grease by counting the number of grease-covered squares on the graph paper. Using the system of the present invention, images were acquired, analyzed, and quantified to provide reproducible and accurate values ​​for the areas stained with grease.

[0029] Figure 3 shows a sequence of images illustrating the transformations applied by the system of the present invention. The first acquired image is shown in frame A of Figure 3. The corners of the image are identified in frame B, and this information is used to transform the perspective of the image, as shown in frame C. Noise is reduced as shown in frame D. The image is then subjected to a processing algorithm for morphological transformation, as shown in frame E, to generate the transformed image in frame F. As shown in the final transformed image in frame F, the shape and overall extent of the grease transferred to the paper are identified by the analysis unit, and reproducible and quantifiable values ​​of the defects are obtained. Figure 4 shows a parity plot comparing the percentage of grease leakage counted by the observer with the percentage of leakage identified and quantified by the image analysis process of the present invention. Representative samples of the acquired and transformed images are shown in Figures 5A and 5B, respectively.

Claims

1. A method for quantifying liquid leakage from a barrier coating, a) A system for acquiring and analyzing images, i) An imaging system for acquiring one or more images of a wet substrate, ii) A lighting system including at least one light source for illuminating the wet substrate, iii) A holder for holding the wet substrate in a position illuminated by at least one light source, iv) To provide a system including an analysis unit configured to convert one or more images and to quantitatively analyze the one or more converted images for liquid leakage of the barrier coating, b) Loading the wet substrate containing the liquid that has passed through the barrier coating into the holder, c) Illuminating the wet substrate using the lighting system, d) Acquiring at least one image of the wet substrate using the imaging system, e) Transforming the at least one image of the wet substrate using the analysis unit, wherein the transformation of the at least one image of the wet substrate includes processing the at least one image of the wet substrate using an algorithm selected from the group consisting of image thresholding, wavelet transform, morphological transformation, color detection, pattern detection, clustering, and combinations thereof to provide at least one transformed image, and quantifying the liquid leakage of the barrier coating based on the at least one transformed image. f) A method comprising providing an output which includes a value that identifies the amount or proportion of the liquid on the wet substrate, and / or a generated image showing the amount or proportion of the liquid on the wet substrate.

2. The method according to claim 1, wherein the imaging system is configured to acquire images in a plurality of channels, each of the plurality of channels includes a predetermined range of wavelengths, and the plurality of channels include channels selected from at least one of the visible light spectrum, the infrared spectrum, and the ultraviolet spectrum.

3. The method according to claim 1 or 2, wherein at least one of the imaging system and the holder is adjustable to change at least one parameter selected from the angle between the imaging system and the holder, the distance between the imaging system and the holder, and the relative position between the imaging system and the holder, and acquiring at least one image of the wet substrate using the imaging system includes adjusting the relative position between the imaging system and the holder to acquire at least two images of the wet substrate at different positions.

4. The method according to any one of claims 1 to 3, wherein at least one of the illumination system and the holder is adjustable to change at least one parameter selected from the angle between the illumination system and the holder, the distance between the illumination system and the holder, and the relative position between the illumination system and the holder, and acquiring at least one image of the wet substrate using the imaging system includes adjusting the relative position between the illumination system and the holder to acquire at least two images of the wet substrate at different positions.

5. The method according to any one of claims 1 to 4, wherein the at least one light source includes a ring light or a diffuse light source.

6. The method according to any one of claims 1 to 5, wherein the at least one light source emits light from at least one spectrum selected from the visible light spectrum, the infrared spectrum, and the ultraviolet spectrum.

7. The method according to any one of claims 1 to 6, wherein the imaging system further includes at least one filter, the at least one filter preferentially transmits light of one wavelength among the plurality of channels, or preferentially blocks light of one wavelength among the plurality of channels.

8. The method according to any one of claims 1 to 7, further comprising displaying the output on a graphical user interface (GUI).

9. The method according to any one of claims 1 to 8, wherein transforming the at least one image of the wet substrate includes morphological transformation.

10. The method according to any one of claims 1 to 9, further comprising: preparing the wet substrate by placing a barrier coating on the upper surface of the substrate; applying a liquid to the upper surface of the barrier coating; and allowing the liquid to penetrate the barrier coating for a predetermined time to form the wet substrate.

11. The method according to any one of claims 1 to 10, wherein the liquid is selected from water, oil, or fat.

12. The method according to claim 11, wherein the liquid is selected from oil or fat.

13. The method according to any one of claims 1 to 12, wherein the wet substrate includes an absorbent material.

14. The method according to claim 13, wherein the absorbent material is paper.

15. The method according to any one of claims 1 to 14, wherein the barrier coating includes a barrier coating formed on paper.

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