Method developed for objective measurement of water repellency properties of textile materials

Abstract

The invention relates to a method developed for the objective measurement of water repellency properties of fabrics developed for use in the textile industry. The invention particularly relates to a method that enables the determination / measurement of water repellency properties of fabrics in factories and experimental laboratories producing fabrics, image analysis and obtaining temperature value data at each pixel (point), and temperature change and wettability in the sample.

Description

[0001] METHOD DEVELOPED FOR OBJECTIVE MEASUREMENT OF WATER REPELLENCY PROPERTIES OF TEXTILE MATERIALS

[0002] Field of the Invention

[0003] The invention relates to a method developed for the objective measurement of water repellency properties of fabrics developed for use in the textile industry.

[0004] The invention particularly relates to a method that enables the determination / measurement of water repellency properties of fabrics in factories and experimental laboratories image analysis and obtaining temperature values data at each pixel (point), and temperature change and wettability in the sample.

[0005] State of the Art

[0006] In the textile industry, textile materials are expected to have different properties due to their places of use. One of these features is water repellency against water and liquids, which is generally desired in outerwear and home textiles. Liquids such as tea, coffee, blood and oil are absorbed by the textile material, causing contamination. Therefore, water repellency finishing process is applied with various chemicals to prevent the penetration of such liquids.

[0007] Subjective and objective methods are used to detect water repellency in the art. In the subjective evaluation, after the samples are wetted (spray test, Bundesmann, etc.), they are compared with the reference fabric photos and scored. In the objective evaluation, the angle between the drop left on the fabric and the fabric (contact angle) and the spread of the drops to the edges and bottom surface (MMT) are measured. However, due to the existing disadvantages in subjective measurement methods, the following problems are experienced in obtaining accurate and repeatable results; a) Evaluations made according to the reference photographs vary according to the lighting of the environment or the operator, thus leading to different results. b) Since numbered subjective scales from 0 to 5 are used in the current analyses, the precision is low in measurement technique. For example, despite providing a rating like "degree of wetting (3-4)," it is not possible to present a result such as 61 .6%. c) Some fabric colors (very light and very dark colors) make evaluating difficult and inaccurate results are obtained. d) There are different studies in the literature for the objective evaluation of water repellency. In these studies; test methods measured over a single drop (contact angle measurement, liquid moisture transmission (MMT), etc.) do not represent real use. For example, in the contact angle experiment, measurements are made of the surface tension between a drop of liquid and the fabric. In addition, there is no measurement of the spread of the liquid on the surface with the capillary effect caused by the gaps in the fabric structure. It is seen that studies on objective measurement of both surface tension and spread are not applicable in practice.

[0008] As a result, due to the disadvantages and the insufficiency of the current solutions regarding the subject matter, development is required in the relevant technical field.

[0009] Objective of the Invention

[0010] The object of the invention is to solve said disadvantages by being inspired from the current conditions.

[0011] The main object of the invention is to develop an objective method in which the problems experienced in the current art are eliminated, precise measurement can be made, and the resistance of fabric surfaces to wetting is measured to determine the water repellency property.

[0012] An object of the invention to ensure that the degree of wetting is displayed with a thermal camera. In addition to image analysis, it is based on the measurements of wettability with the temperature change in the samples by obtaining temperature value data at each point (in pixels). Using the thermal difference in the wetted regions / zone with the invention, it is ensured that the degrees of wetting of the samples are measured with very high precision according to objective and relevant standards by using the image processing technique with the help of the thermal camera's ability to color the regions at different temperatures differently. Another object of the invention is to provide a measurement method that simulates the actual use situation.

[0013] Another object of the invention is to develop a new measurement method that will enable repeatable results to be obtained in different fabric types.

[0014] In order to fulfill the above objects, the invention is a method of objectively measuring the water repellency properties of textile material comprising the following process steps; i. Wetting of the textile samples, ii. Recording images of wetted samples with a thermal camera, iii. Obtaining temperature data of each pixel in the images recorded by thermal image analysis, iv. Determination of the wet zone and dry zone according to the temperature differences on the sample, v. Calculation of the number of pixels in the wet zone using the analysis program, vi. Calculating the wetting value as a percentage by dividing the number of pixels in the wet zone by the total number of pixels in the entire area

[0015] The structural and characteristic features and all advantages of the invention will be more clearly understood using the following figures and the detailed description concerning these figures. Therefore, the assessment should be made while considering the figure and their detailed descriptions.

[0016] Figures for a Better Understanding of the Invention

[0017] Figure 1 , A representation of the system for measurement with a thermal camera.

[0018] Figure 2, View from the Thermal Image analysis.

[0019] Descriptions of Part References

[0020] 1. Thermal camera

[0021] 2. Measurement chamber

[0022] 3. Sample holder

[0023] 4. Movable rail system 5. Thermal Image Analysis Example

[0024] 5.1 Wet zone

[0025] 5.2 Dry zone

[0026] N: Sample

[0027] Detailed Description of the Invention

[0028] In this detailed description, the preferred embodiments of the method of the invention are described only for a better understanding of the subject.

[0029] The invention relates to a method for objectively measuring the water repellency properties of textile materials. The method in question comprises the following process steps; i. Wetting of textile materials in accordance with test standards, ii. Recording images of wetted samples with a thermal camera (1 ), iii. Obtaining temperature data of each pixel in the images recorded by thermal image analysis, iv. Determination of the wet zone (5.1 ) and dry zone (5.2) according to the temperature differences on the sample, v. Calculation of the number of pixels in the wet zone (5.1 ) using the analysis program, vi. Calculating the wetting value as a percentage by dividing the number of pixels in the wet zone (5.1 ) by the total number of pixels in the entire area

[0030] In the process step iii) of the method of the invention, temperature data are obtained from more than 30,000 pixels on the measurement area with the Image analysis program. Temperature values are transferred to excel. In process step iv), the sections where temperature differences occur on the sample, with lower average temperatures, are identified as the wet zone (5.1 ) and the other sections are designated as the dry zone (5.2). Here, it is critical to evaluate the temperature difference value in the detecting wet / dry zones in image analysis. In the determining the wet zone (5.1 ) and the dry zone (5.2) according to the temperature differences on the sample, the low average temperature in the determined zone means that the wetting increases and therefore the subjective evaluation result is a lower value. The pixels below the defined temperature value are determined as the wet zone (5.1 ) and the number of pixels in the wet zone (5.1 ) is calculated by excel. Then, this value (the number of pixels in the wet zone (5.1 )) is divided by the total number of points and the "wetting" value is calculated as a percentage.

[0031] Wetted materials absorb the heat on the surface and use this heat to evaporate. Evaporation can occur at any temperature. Since energy is consumed for evaporation on wetted surfaces, cooling occurs regionally. Temperature differences can be detected by infrared radiation using the thermal cameras. Therefore, temperature differences in case of wetting can be detected with thermal cameras. In the method of the invention, the thermal difference in said wetted regions was used; in addition, thanks to the thermal camera's ability to color the regions at different temperatures differently, the degrees of wetting of the samples were measured with very high precision according to objective and relevant standards using the image processing technique. Wettability can be measured with very high precision by obtaining temperature data from over 30,000 pixels (points) over the zone used in the measurement.

[0032] In the method of the invention, images of wet samples are taken with a thermal camera. The recorded images are transferred to the computer and the temperature values of each pixel in the photo are taken with the thermal camera analysis program, and then the values are transferred to excel, and the analysis is performed.

[0033] Figure 1 shows the mechanism for measurement after the process (before the evaluation) according to the ISO 4920 test standard. Here, a measurement chamber (2) is used to not be affected by the external environment. The interior of the cabinet is dark in color so that light is absorbed and not reflected on the sample (N). A dark environment has been created since there is no need for lighting as in digital camera measurements. There is a gap on the short edge of the measurement chamber (2) for the placement of the camera lens. The sample (N) is placed on the sample holder (3) (perpendicular to the floor). To allow for focus adjustment, the sample holder (3) is placed in the movable rail system (4) as a movable mechanism. Figure 2 provides the view from the Thermal Image analysis. The temperature data of each pixel (point) inside this circular zone (measurement area) can be obtained. Based on the principle of cooling the wetted surface, the sections where the temperature difference occurs are considered as "wet". With the following formula, the % value of the wet zone is calculated. the number of pixels in the wet zone Wetness value ((%)) = — - ; - - - ; - ; - the number of pixels in the entire area

[0034] In the method of the invention, images of samples which were subjected to water repellency process are recorded with a thermal camera. Thermal images of the wetted samples are transferred to the computer. Photographs are analyzed with the image analysis program. The temperature values in each pixel inside the circular zone measured are taken from the program (Figure 2). Color differences can be determined in pixels. The image analysis program can obtain temperature data from more than 30.000 pixels over the circular zone used in the measurement. It provides wet / dry zone separation by taking advantage of the difference between temperature degrees. Wetted areas have lower temperature values. The temperature values are transferred to Excel. Points (pixels) where the temperature difference value is greater than the defined value are considered wet. From the data stack, the "wetness value %" is calculated by dividing the number of pixels in wet zones by the total number of pixels. The result is obtained by comparing the wetting amount measured with the wetness value in the standard photographs (graded from 0 to 5) where the visual evaluation is made. According to the standard in the state of the art, the water repellency value is gradually given from 0 to 5 (including intermediate values). With the method of the invention, this % can be expressed in a precise manner.

[0035] In a preferred embodiment of the method of the invention, the software called IRSoft2 of the thermal camera (Testo brand) is used. However, apart from this, analysis can be performed with other thermal camera image analysis methods or program.

[0036] ISO 4920 "Spray test" method is most commonly used for the determination of surface wetting (water repellency) in fabrics. In this standard and many other standards; analyses are required to be carried out under the ambient conditions specified in the ISO 139 standard. Therefore, all measurements in the invention-are carried out at these temperature and humidity values. According to the ISO 139 standard, the samples are kept at 20±2 °C and 65±4% relative humidity for at least 1 day. Measurements are carried out in this environment and the water temperature is 20 °C.

[0037] An exemplary embodiment of the method of the invention is given below:

[0038] According to the ISO 4920 test standard, 250 ml of liquid is poured on the fabric surface. The treated samples (N) are placed in the measurement chamber (2) in order to obtain an image with the thermal camera (1 ). The sample (N) is placed in the sample holder (3) perpendicular to the floor. In order to obtain the image clearly, it is necessary to make focus adjustment. For this purpose, the sample holder (3) placed on the movable rail system (4) is shifted left and right. The thermal image of the sample (N) is recorded. After obtaining the thermal image of the sample (N), temperature distribution analysis is carried out. Temperature values of each point (pixel) can be obtained. With the temperature difference formed according to the cooling principle of the wetted area; wet zone (5.1 ) and dry zone (5.2) can be determined.

[0039] A study for the analysis of the method of the invention was carried out as follows; Measurements were made with samples of different structures. After the samples are wetted in accordance with the ISO 4920 standard, they are placed in a chamber so that they are not affected by the effects of the external environment. Photographs were recorded with a thermal camera. The wetting amount was determined by examining the temperature distributions in the thermal photographs. The values obtained by proportioning the wet / dry documents in the circular zone were compared with the reference photographs in the ISO 4920 standard. The score values of the degrees of wetting in the fabrics (between 0 and 5) were compared with the values obtained as a result of the method of the invention (Table 1 ). The average temperature and "dry zone %" values of the circular zone in the thermal camera image were calculated. It was detected that the score value obtained from of the visual evaluation of the samples by comparing them with standard photographs and the value obtained as a result of the calculation were the same.

[0040] Table 1 Data of measurement results

[0041] The fact that the average temperature in the determined area is low means that wetting increases. This result means that if wettability is evaluated with a subjective method, a low score will be obtained. For example, in the sample where the average temperature given in Table 1 above is 18.7 O, wetting is evalu ated as medium level (score:3) as a result of subjective evaluation, while wetting is evaluated as low (score 0-1 ) in the sample where the average temperature is measured as 17.8 °C.

[0042] In existing image analyses used in the literature, ambient (environmental) conditions and sample characteristics affect the results. The method of the invention differs from the image analyses in the literature by using a thermal camera (1 ) and provides originality. For this reason, it will not be possible to obtain the desired result if the existing alternative components (microscope, checkered paper, etc.) are used instead usage of the thermal camera (1 ) in the method of the invention.

[0043] The method of the invention can be used in other applications (for example, capillary, waterproofing, etc.) where the fabric structures interact with the liquid and wetting occurs.

Claims

CLAIMS1. A method of objectively measuring the water repellency properties of textile materials, characterized by comprising; the following process step: i. Wetting of the textile samples, ii. Recording images of wetted samples with a thermal camera (1 ), iii. Obtaining temperature data of each pixel in the images recorded by thermal image analysis, iv. Determination of the wet zone (5.1 ) and dry zone (5.2) according to the temperature differences on the sample, v. Calculation of the number of pixels in the wet zone (5.1 ) using the analysis program, vi. Calculating the wetting value as a percentage by dividing the number of pixels in the wet zone (5.1 ) by the total number of pixels in the entire area.

2. The method according to claim 1 , characterized in that; in process step i), the textile samples are wetted according to experimental standards, preferably ISO4920 standards.

3. The method according to claim 1 , characterized by comprising; in process step iii), temperature data are obtained from more than 30,000 pixels on the measurement area with the Image analysis program.

4. The method according to claim 1 , characterized in that; in process step iv), the sections of the sample where the temperature difference occurs, where the average temperature is lower, are determined as the wet zone (5.1 ) and the other sections as the dry zone (5.2).

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