KR101224476B1 - Quantitative determination of scratch visibility for polymeric and coating materials - Google Patents

Abstract

The present invention shows the visibility of the surface damage due to scratches and scratches generated on the surface of the polymer and the coating material as a numerical value quantified through three-dimensional color coordinates, and using the scratch visibility index (Scratch Visibility) Index, SVI) to quantify and evaluate the visibility of the surface damage of the material by calculating, in order to quantify the visibility of the surface damage by the scratches generated on the surface of the polymer and coating material, Preparing a specimen; Generating a scratch on the surface of the test piece; Scanning the surface damage caused by the scratch to obtain an image; Using color analysis software to color-code the image for each pixel to profile change trends of surface damage in color coordinates; Sizing the change trend of the load applied to the surface of the color coordinates and the test piece and distinguishing and combining only the components related to the scratch visibility and represented by the scratch visibility index (SVI); Quantifying the scratch visibility of the polymer and coating material, comprising a Provide a method.

Description

Quantative determination of scratch visibility for polymeric and coating materials}

The present invention relates to a method for quantifying scratch visibility of a polymer and a coating material, and more particularly, to three-dimensional color coordinates of the visibility of surface damage due to scratches and scratches generated on the surface of the polymer and the coating material. The present invention relates to a method of quantifying and evaluating the visibility of surface damage of a material by expressing it as a quantified value through the SVI and using the same to calculate a Scratch Visibility Index (SVI).

In recent years, as the quality of sensitivity is important, the surface properties of polymers and coating materials, such as surface roughness, hardness, friction, wear, scratch and scratch characteristics, etc. The importance of research is on the rise, and there is a growing interest in evaluation techniques that can clearly quantify the scratch properties of polymers and coating materials.

Although recent ASTM (D7027-05) and ISO standards (19252: 2008) describe quantitative assessments of surface damage due to scratches, these standard test methods focus on the test methodology and observation of the shape of surface damage. I put it.

For example, ISO 19252 evaluates the surface damage caused by scratching by classifying the surface into puffing, wedging formation, or cutting depending on the appearance of the portion where the scratch tip has passed.

However, the evaluation method as described above has a problem in reproducibility, difficulty in objectification and deterioration in discrimination because the boundary is very subjective according to the observer and thus can be evaluated depending on individual judgment.

In addition, in ASTM (D7027-05), scratches occur on the surface of the material at relatively low constant loads, and when the additional constant loads are applied, deepening of whitening occurs. The surface damage of the material is quantitatively evaluated based on the criterion of the vertical load, that is, the critical normal load, at this point.

However, since the critical vertical load is not a normalized material property divided by unit length or area, it is difficult to generalize to a measurement and evaluation factor because it can be evaluated based on individual judgment of the experimenter. .

Therefore, in evaluating the visibility of the surface damage of the material by scratching, there is a need for an efficient and more quantitative evaluation method that can replace the inefficient conventional evaluation methods.

The present invention has been made in view of the above problems, and in evaluating the visibility of surface damage caused by scratches and scratches generated on the surface of polymers and coating materials under linearly increasing load, Surface damage caused by scratching by artificially generating scratches on the surface of the material using scratch tips capable of line contact, and then quantifying the visibility of the surface damage in three-dimensional (3-D) color coordinates of the color model. The purpose of the present invention is to provide a method for quantifying scratch visibility of polymers and coating materials having better reliability and reproducibility by calculating the visibility of quantified values, that is, the scratch visibility index (SVI).

In order to achieve the above object, the present invention, in order to quantify the visibility of surface damage caused by scratches generated on the surface of the polymer and coating material,

Preparing a test piece of a polymer and a coating material; Generating a scratch on the surface of the test piece; Scanning the surface damage caused by the scratch to obtain an image; Using color analysis software to color-code the image for each pixel to profile change trends of surface damage in color coordinates; Sizing the change trend of the load applied to the surface of the color coordinates and the test piece and distinguishing and combining only the components related to the scratch visibility and represented by the scratch visibility index (SVI); Quantifying the scratch visibility of the polymer and coating material, comprising a Provide a method.

Preferably, the scratch of the step of generating the scratch is characterized in that it is generated using a scratch tip capable of linear contact with the surface of the test piece.

Also preferably, the scratch in the step of generating the scratch is characterized in that generated by applying a linear increasing load on the surface of the test piece.

And preferably, in analyzing the surface damage of the test piece by the scratch, it is characterized by applying a color analysis technique using a three-dimensional color model.

More preferably, the color analysis software for profiling with the color coordinates is capable of color analysis of all or any selected area in analyzing the surface damage of the specimen.

Also preferably, the color analysis software is characterized in that the color coordinates representing each column j of the image according to the scratch direction is represented by an average value of all the color coordinate values of the column j.

More preferably, the color analysis software is capable of continuously measuring the width and length of the total scratches on the surface of the specimen.

)의 조합인 [I _c , S _c ,

]으로 나타내는 것을 특징으로 한다.The scratch visibility index may include brightness values I _c , saturation values S _c , and threshold scratch resistances at the time when occurrence of surface damage of a test piece is recognized.

) Is a combination of [ I _c , S _c ,

It is characterized by.

More preferably, the scratch tip is in contact with the surface of the test piece in a horizontal direction to induce scratch damage at a certain distance and a constant speed.

The present invention enables the objective evaluation of scratch visibility by calculating quantitative numerical values of the visibility of surface damage due to scratches and scratches generated on the surface of the polymer and the coating material. Can reduce errors and ensure reliability for scratch resistance evaluation.

In addition, the method according to the present invention can objectively evaluate the visibility of surface damage caused by scratching of all polymers and coating materials by expressing the visibility of surface damage caused by scratch by the Scratch Visibility Index (SVI). .

Figure 1 is a test flow chart showing a comparison of the conventional method and the method of quantifying the scratch visibility of the polymer and the coating material according to the present invention.
Figure 2 schematically illustrates the specific shape of the scratch tip used in the present invention and the shape of the material surface damage induced under linear increase load.
3 is a schematic diagram illustrating color coordinates of an HSI color model.
4 is a schematic diagram illustrating a method of taking color coordinate values representing each column of an image using color analysis software used in the present invention.
5 is a surface damage image due to scratches and scratches under a linear increase load obtained from a flatbed scanner in an embodiment of the present invention.
FIG. 6 is a graph illustrating three color coordinates of the color analysis result of the exemplary embodiment of the present invention and a change trend of the corresponding scratch resistance according to the scratch trajectory. FIG.
FIG. 7 is an optical micrograph of regions I, II and III shown in FIG. 5, wherein (a) is the first color transition point, (b) is the second color transition point, and (c) is near the third color transition point. Shows surface damage forms.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the invention. In the description, overlapping descriptions of the same parts as well-known technologies may be omitted.

The present invention relates to a method for quantitatively evaluating the visibility of surface damage due to scratches and scratches generated on the surfaces of polymers and coating materials in a quantitative manner. Using scratch tips that line contact the surface of the material under linearly increasing load conditions to induce surface damage by scratching, scan the surface damage site to obtain a digitized image and save it. Using the color analysis software, the change of surface damage caused by scratch is profiled with the color coordinates of the 3-D color model. Finally, the change of the color coordinates and the working stress according to the scratch trajectory is plotted. Scratch Visibility Index, which is the final quantified value by discriminating and combining only components related to scratch visibility , SVI).

Hereinafter, with reference to the accompanying drawings and embodiments will be described in detail the present invention.

In the present invention, the polymer and the coating material refer to a coating material formed on the surface of various materials together with the polymer material, and in the present specification, a 'polymer and a coating' are omitted and will be referred to simply as a 'material'.

As shown in Fig. 1, in order to evaluate the scratch resistance through the scratch test under linearly increasing load conditions, a test piece of a selected material is first prepared, and the test piece is artificially induced to damage the surface by damaging the surface.

In order to apply scratched surface damage, that is, scratch damage to the surface of the test piece, a scratch test is carried out under a linear increase load.As a scratch generator for damaging the surface of the test piece, a general scratch generator may be used, and the present invention may be carried out. In the example, a scratch test was performed using a UMT-2 model from Center for Tribology, Inc.

In the present invention, the scratch generator is an apparatus for artificially generating scratches and scratches on the surface of the test piece and includes a scratch tip capable of line contact with the surface of the material, the material of the scratch tip is to damage the surface of the material It is preferably a metal, mineral or inorganic material of higher hardness than the polymer and the coating material.

In the present invention, the scratch tip is in contact with the surface of the material under a linearly increasing load condition to exert a stress for scratch generation.

To this end, the scratch generator controls the scratch tip to exert a linear increasing load on the surface of the specimen.

The scratch tip is in horizontal contact with the surface of the specimen under linearly increasing load (eg, 1 to 30 N) in the scratch test to induce scratch damage at a constant distance (length) and at a constant speed.

In other words, the scratch tip is in contact with the surface of the specimen in the horizontal direction in order to induce scratch damage on the surface of the specimen to apply a linear increase load at a constant distance and constant speed.

FIG. 2 schematically illustrates the shape of the scratch tip used in the present invention and the shape of the material surface damage induced under the linear increase load, and shows the surface damage of the specimen due to the linear increasing load according to the scratch trajectory. As shown, the damage created on the surface of the specimen is subjected to the first color transition point (1st), second color transition point (2nd), and third color transition point by applying a linearly increasing load along the scratch direction. (3rd) appears sequentially.

When surface damage such as scratches and scratches are generated on the surface of the test piece, the surface damage area is scanned using a device such as a scanner to acquire and store a digitized image.

Here, the digitized image is a digital image of the surface of the scratched material with a minimum resolution of 600 × 600 dpi or higher, 24-bit color mode, in the embodiment of the present invention, for example, using the Perfection V700 photo model of Epson Image was acquired.

After digitally imaging the scratch damage on the surface of the specimen as described above, the surface damage along the trace path of the input image, i.e., the scratch trace of the input image, is generated by using the color analysis software. Digitize with three color components (color coordinates) of 3-D color model.

Here, the color analysis software is a program that can measure and display the change trend of the surface damage along the scratch trajectory of the image by the color coordinate value of the three-dimensional color model, in the present invention by using it to measure the visibility of the surface damage by scratch The scratch resistance of the material can be evaluated.

In the embodiment of the present invention, a commercial color analysis program QWin was used, and the color analysis results are expressed in color coordinates of HSI, which is a 3-D color model.

The color coordinates are represented by three different components representing unique color values for each pixel of the digitized image. For example, in the case of the RGB color model, the red (R) and green (Green) colors are represented. Value (G) and blue value (B), and in the case of the HSI color model, as shown in FIG. 3, a hue value H, a saturation value S, and an intensity value ( It is expressed by I).

The hue or hue value is a component expressing the color itself, the saturation or saturation value is a component indicating how much white is contained, and finally, the brightness or brightness value is a component indicating the brightness (luminance) of the color. Each component is represented by a number from 0 to 255, and each pixel of the image obtained through the scanning operation may represent a unique color of the pixel as a combination of the three color components, that is, color coordinates.

The color analysis software is not only capable of continuously measuring the width and length of the total scratches on the surface of the test piece, but is also capable of arbitrarily selecting the area of damage on the test piece surface to measure the visibility of the surface damage.

In addition, when the color analysis software evaluates an arbitrary selection area (damage area of a randomly selected material surface), the color coordinates representing each row j according to the scratch direction as shown in FIG. For example, the average value of the color coordinate values may be represented by [R _j , G _j , B _j ], which is represented by Equation 1 below.

4 is a schematic diagram illustrating a method of taking color coordinate values of each column according to a scratch direction using color analysis software. Referring to this in more detail, the color analysis software includes an image analysis area obtained from a damaged part of a surface of a specimen. Each pixel of the image is classified by column (j) along the scratch direction with respect to the entire or randomly selected area, and the color coordinates representing each classified column (j) are represented by the average of all color coordinate values of the corresponding column (j). .

In the present invention, with reference to the color coordinates representing each column j according to the scratch direction in the case of the RGB color model can be expressed as Equation 1, in the case of the HSI color model can be represented as Equation 2 below Can be inferred.

Therefore, the color coordinates representing each column j according to the scratch direction in any selected region of the image analysis region of surface damage are [R _j , G _j , B _j ] or [H _j , S _j, I _j ], etc. It can be expressed as

Based on the color analysis results, the final quantified scratch visibility index (SVI) is calculated by plotting the change of color coordinates and the increase of the working stress according to the scratch trajectory in one chart.

)의 조합으로 표현될 수 있고, 본 발명에서는 상기 스크래치 시인성 지수를 아래 수학식 3와 같이 정의한다.Scratch visibility indexes include color coordinates and threshold scratch resistance at the point when scratch visibility is detected, that is, when occurrence of surface damage is recognized.

), And in the present invention, the scratch visibility index is defined as in Equation 3 below.

Here, I _c and S _c are brightness values and chroma values at the time when surface damage of the test piece is recognized, that is, brightness values and chroma values at the visibility start point described later.

)은 아래 수학식 4와 같이 계산한다.together Scratch resistance (

) Is calculated as in Equation 4 below.

)은 시험편의 표면 손상이 인식되는 시점에서의 스크래치 저항(

)을 의미한다.Where l is the length the scratch tip is in contact with the material surface, and the critical scratch resistance (

) Is the scratch resistance at which the surface damage

).

)은 두 법선 벡터인 수직하중(

)과 접선하중(

)의 합으로서, 스크래치 시험시 제공되는 선형증가하는 하중에 따라 결정되며, 아래 수학식 5와 같이 구한다. Scratch force, which moves the scratch tip in line contact with the surface of the specimen, can cause scratch damage to the specimen.

) Is the normal load (two normal vectors)

) And tangential load (

) Is determined by the linear increasing load provided during the scratch test, and is obtained as shown in Equation 5 below.

)은 스크래치 팁을 통해 소재 표면에 수직방향으로 작용하는 하중이고, 접선하중(

)은 스크래치 팁을 통해 소재 표면에 수평방향으로 작용하는 하중이다.Where vertical load (

) Is the load acting perpendicular to the surface of the material through the scratch tip, and the tangential load (

Is the load acting horizontally on the material surface through the scratch tip.

In the present invention, there is no particular limitation on the thickness of the material in quantifying the visibility of scratch damage applied to the surface of the material, but a test piece having a thickness of 10 mm or less is preferable, and a flat specimen having a minimum length of 70 mm or more and no bending is used. It is preferable.

The invention can be better understood through the following examples, which are intended to illustrate the invention and are not intended to limit the appended claims.

Example

In the present invention, a flat polypropylene composite material having a thickness of 3 mm was used as a test piece for scratch visibility evaluation.

A total of 50 mm of scratch was applied to the specimen using a scratch generator. At this time, the scratch speed (speed to generate scratch damage) was fixed at 1 mm / s and the experimental load condition was given a linear increasing load of 1 to 30N.

In this embodiment, the scratch tip has the shape of FIG. 2 and has a length in contact with the surface of the test piece. 1 mm was used.

Through the above procedure, the surface of the material from which surface damage such as scratching and scratching was induced was digitally imaged using a flatbed scanner device.

5 shows surface damage images by scratches and scratches obtained from the flatbed scanner.

In this example, only about 90% of the total scratch width was arbitrarily selected (see FIG. 2), and color analysis was performed using an HSI color model.

)의 변화추이 등을 스크래치 궤적에 따라 도식화하여 나타낸 그래프이다.FIG. 6 shows three color coordinates (H, S, I) and the corresponding scratch resistance as a result of color analysis of the present embodiment.

) Is a graph showing the change trend of) according to the scratch trajectory.

)은 선형적으로 증가하고, ② 색조값(H)은 거의 일정한 값을 유지하는 반면, ③ 밝기값(I)의 증가 및 ④ 채도값(S)의 감소 경향을 보였다. As the scratch trajectory increases (the scratch length increases), as shown in FIG. 6, the scratch resistance (

) Increased linearly, and ② the hue value (H) remained almost constant, whereas ③ increased the brightness value (I) and decreased the ④ saturation value (S).

)이 스크래치 궤적을 따라 증가하게 되면 스크래치된 홈(groove) 부근에서 표면 손상으로 인한 빛의 산란이 증가하는 백화(whitening)현상이 발생하게 됨을 알 수 있다.That is, the scratch driving force (

If the) increases along the scratch trajectory, it can be seen that whitening occurs due to increased scattering of light due to surface damage in the vicinity of the scratched groove.

In addition, the whitening of the material due to scratching causes a change in the color coordinate. Specifically, the brightness value (I) and the saturation value (S) of the HSI color model directly change the value while reflecting the whitening phenomenon. , Hue value (H) was maintained a constant value irrespective of whitening phenomenon.

Referring to the profiles of the brightness value I and the saturation value S according to the scratch trajectory in FIG. 6, the slope of these values continuously changes as the degree of surface damage caused by the scratch increases. Can be observed.

For example, in the case of the brightness value I in FIG. 6, the value in the scratch-free zone (No damage zone in FIG. 6) remains constant and then scratches past the first color transition point. It enters the creation zone (Mar zone of FIG. 6), increases and remains constant again, then increases again through the second color transition point, and then remains constant. It can be seen that it is repeatedly reproduced.

On the other hand, in the case of the saturation value S in FIG. 6, the initial value is kept constant and then decreases and remains constant even after entering the scratch generation region (Mar zone of FIG. 6) past the first color transition point. After the second color transition, it decreases again and then remains constant, after which the phenomenon is repeatedly reproduced.

As described above, the inclination change of the brightness value I and the saturation value S in FIG. 6 means that the color coordinate value, in particular, the brightness value and the saturation value can be used as an identification index indicating a change in the degree of surface damage.

)과 연관이 있음을 알 수 있고, 스크래치 시인성 지수는 이들을 조합하여 도출할 수 있음을 짐작할 수 있다.As described above, the visibility of the scratches generated on the surface of the material has the brightness value (I), the saturation value (S), and the scratch resistance (

), And the scratch visibility index can be estimated by combining them.

On the other hand, observation using an optical microscope was performed to correlate the color shift point of FIG. 6 with the form of surface damage.

(A), (b) and (c) of FIG. 7 are enlarged optical micrographs of the regions I, II and III shown in FIG. 5, respectively, and the surfaces near the first, second and third color transition points, respectively. Show the form of damage.

As shown in FIG. 7, region I shows a mar phenomenon, which is a relatively light surface damage, and region II shows a superimposition of wavy surface damage. This surface damage is visualized even with the naked eye, and in the embodiment of the present invention, the second color shift point of FIG. 6 is more identifiably determined as an "onset of scratch visibility".

)의 조합인 [I _c , S _c ,

]을 “스크래치 시인성 지수”로 결정한다. In addition, the present invention provides a brightness value ( I _c ), a saturation value ( S _c ), and a scratch resistance at the starting point of visibility.

) Is a combination of [ I _c , S _c ,

] Is determined by the “scratch visibility index”.

Table 1 shows the test results of the above examples in terms of scratch visibility index (SVI).

In the present embodiment, the method for evaluating the visibility of surface damage by scratching and scratching according to the present invention was found to be more easily quantified by expressing the visibility of surface damage as a digitized value.

On the other hand, region III was found to be larger in the width of the wave pattern as the scratch damage proceeds to the vicinity of the third color transition point.

As such, the present invention can quantify the visibility of surface damage due to scratches and scratches generated in polymers and coating materials, as well as deriving the scratch visibility index as a final quantified result, thus easily quantifying scratch visibility, which was difficult to quantify conventionally. It has the effect of being physicalized.

In addition, it can be seen that the quantified values indicating the visibility of the surface damage, as confirmed through the above examples, are a result of a small error due to the measurer and the measurement environment, and high reliability and reproducibility.

In addition, the quantification method according to the present invention can be applied to a wide range of polymers and coating materials, regardless of the color of the surface, the presence or absence of the surface pattern, and the pattern shape.

Simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be regarded as being included in the scope of the present invention.

Claims (9)

In order to quantify the visibility of surface damage by scratches generated on the surface of the polymer and the coating material,
Applying a linear increase load to the surface of the test piece of polymer and coating material with a scratch tip capable of inducing scratch damage;
If scratch damage is generated on the surface of the test piece, the surface damage area is scanned, the digitized image is acquired and stored, and color analysis is performed for each pixel using color analysis software to change the trend of surface damage in color coordinates. Profiling;
Schematically illustrating the change trend of the load applied to the surface of the color coordinates and the specimen, and discriminating and combining only the components associated with the scratch visibility as a scratch visibility index (SVI);
Scratch visibility quantification method of the polymer and coating material comprising a.
delete delete The method according to claim 1,
The method of quantifying scratch visibility of a polymer and a coating material, characterized in that to apply a color analysis technique using a three-dimensional color model in analyzing the surface damage of the specimen by the scratch.
The method according to claim 1,
The color analysis software of the step of profiling with color coordinates is a method for quantifying scratch visibility of the polymer and coating material, characterized in that the color analysis of the entire or any selected area in analyzing the surface damage of the specimen.
The method according to claim 1 or 5,
The color analysis software is a method of quantifying scratch visibility of the polymer and coating material, characterized in that the color coordinates representing each column j of the image according to the scratch direction is represented as the average value of all the color coordinate values of the column (j).
The method according to claim 1 or 5,
The color analysis software is a method for quantifying scratch visibility of the polymer and coating material, characterized in that the continuous measurement of the width and length of the entire scratch on the surface of the test piece.
The method according to claim 1,
The scratch visibility index is the brightness value (Ic), the saturation value (Sc), and the critical scratch resistance at the time when the occurrence of surface damage of the test piece is recognized.

) Is a combination of [ I _c , S _c ,

The scratch visibility quantification method of a polymer and a coating material characterized by the above-mentioned.
The method according to claim 1,
The scratch tip is in contact with the surface of the test piece in a horizontal direction to induce scratch damage at a predetermined distance and a constant speed, characterized in that the scratch visibility of the polymer and coating material.

Images