KR102633648B1 - Evaluation Method For Physical Properties of Coating Film - Google Patents

Abstract

The present specification includes the steps of measuring the drying time for a coating film formed by a paint applied on a substrate; A method for evaluating the physical properties of a coating film is disclosed, including the step of measuring one or more of adhesion and hardness according to drying time. According to exemplary embodiments of the present invention, it is possible to provide a method for measuring the physical properties of a coating film formed by a paint applied on a substrate as a quantitative value and evaluating it objectively and accurately.

Description

{Evaluation Method For Physical Properties of Coating Film}

The present specification includes the steps of measuring the drying time for a coating film formed by a paint applied on a substrate; A method for evaluating the physical properties of a coating film is disclosed, including the step of measuring one or more of adhesion and hardness according to drying time.

Paint is applied to materials such as furniture, automobiles, and ships to give them new functions and colors. In this way, the coating film formed by the paint applied on the substrate is required to have not only physical properties such as excellent strength, adhesion, and scratch resistance, but also excellent emotional properties such as surface smoothness and gloss. However, research evaluating these properties quantitatively and objectively is minimal.

Republic of Korea Patent No. 10-2144814 performs pencil hardness analysis to evaluate the hardness of fluorine-based polymer membrane. However, it is still limited to qualitative evaluation of physical properties, and when the paint films being compared have similar physical properties, there is a problem that existing physical property tests cannot distinguish and determine the differences. Accordingly, it is necessary to measure the physical properties of the coating film in quantitative values and evaluate them objectively and accurately.

Republic of Korea Patent No. 10-2144814

The present invention was invented to solve the above problems, and the purpose of the present invention is to measure the physical properties of the coating film as quantitative values, and further, to objectively and accurately measure the physical properties by comparing the results obtained by existing measurement methods. It provides a method for evaluation.

In one aspect, exemplary embodiments of the present invention include measuring a drying time for a coating film formed by a paint applied on a substrate; It provides a method for evaluating the physical properties of a coating film, including the step of measuring one or more of adhesion and hardness according to drying time.

According to exemplary embodiments of the present invention, it is possible to provide a method for measuring the physical properties of a coating film formed by a paint applied on a substrate as a quantitative value and evaluating it objectively and accurately.

1A to 1D are schematic diagrams showing the flow of a method for evaluating coating film properties according to an embodiment of the present invention.
Figure 2 is an image of the surface of a coating film according to an embodiment of the present invention measured using an atomic force microscope (AFM).
Figure 3 is a force-distance curve graph showing the surface of a coating film according to an embodiment of the present invention measured by an atomic force microscope (AFM).
Figure 4 is an indentation load-displacement curve graph showing the surface of a coating film according to an embodiment of the present invention measured by a nano indenter.

The terms used in this specification are general terms that are currently widely used as much as possible while considering the function in the present invention, but this may vary depending on the intention of a technician working in the field, precedents, or the emergence of new technology. In addition, in certain cases, there are terms arbitrarily selected by the applicant, and in this case, the meaning will be described in detail in the description of the relevant invention. Therefore, the terms used in this specification should be defined based on the meaning of the term and the overall content of the present invention, rather than simply the name of the term.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as generally understood by a person of ordinary skill in the technical field to which the present invention pertains. Generally understood terms should be interpreted as having the same meaning as the meaning they have in the context of the related technology, and unless clearly defined in the present invention, they should not be interpreted in an idealized or excessively formal sense.

Numerical ranges include the numerical values defined herein. Every maximum numerical limit given throughout this specification includes all lower numerical limits as if the lower numerical limit were explicitly written out. Every minimum numerical limit given throughout this specification includes every higher numerical limit as if such higher numerical limit was clearly written. All numerical limits given throughout this specification will include all better numerical ranges within the broader numerical range, as if the narrower numerical limits were clearly written.

As used herein, the words “comprising,” “having,” and “comprising” are inclusive or open-ended and do not exclude additional unstated elements, methods or steps. As used herein, the term “or combination thereof” refers to all permutations and combinations of the items listed preceding the term. For example, “A, B, C, or any combination thereof” means A, B, C, AB, AC, BC, or ABC, and, if the order is important in a particular context, BA, CA, CB, CBA, BCA. , it is intended to include at least one of ACB, BAC or CAB. Along with this example, combinations containing repetitions of one or more items or terms may be included, such as BB, AAA, MB, BBC, AAABCCCC, CBBAAA, CABABB, etc. Those skilled in the art will understand that there is typically no limit to the number of items or terms in any combination, unless otherwise apparent from the context.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, it is obvious that the present invention is not limited to the following embodiments.

1A to 1D are schematic diagrams showing the flow of a method for evaluating coating film properties according to an embodiment of the present invention.

In one aspect, exemplary embodiments of the present invention include measuring a drying time for a coating film formed by a paint applied on a substrate; It provides a method for evaluating the physical properties of a coating film, including the step of measuring one or more of adhesion and hardness according to drying time.

The substrate may be a glass slide or stainless steel cut to an appropriate size. The above substrate may be one using a dedicated glass bed for a drying time measuring system, which will be described later. The substrate may be glass cut to a size of 3 × 4 cm for the atomic force microscope and nano-indenter, which are test equipment to be described later. The substrate may be a glass slide or stainless steel cut to a size of 3 x 8 cm for the 90° peel tester, which is a test equipment to be described later. The substrate may be ultrasonic cleaned with acetone for 20 minutes and then ultrasonic cleaned with ethanol for 20 minutes and dried.

The coating film may be formed by brushing paint to a certain thickness on a substrate. The brush painting may be done by putting paint on a brush and applying it three times. The thickness of the coating film may be 2 to 6 μm.

Drying of the paint may be performed in a drying room, and the drying room may be a semi-closed environment in which the humidity is maintained at a constant level of 80 RH%. The drying time can be measured by a drying time recorder. The step of measuring the drying time includes measuring the degree of drying according to the drying time. Since the drying time is measured using various measurement methods and equipment for the physical properties of various paints, it may be an arbitrarily determined time to compare the results measured by each equipment under certain time conditions.

Depending on the drying condition, the degree of drying can be divided into dust free dry (DF), touch free dry (TF), and hardened dry (HD). Adhesive drying is a state in which the sample does not stick to your hands when you lightly brush your finger. Fast drying is a state in which no fingerprint marks are left when lightly pressed with a fingertip. Cured drying is a state in which no deformation occurs in the paint film even if you press it hard with your thumb and twist it.

According to one embodiment of the present invention, the step of measuring roughness according to drying time for the coating film formed by the paint applied on the substrate, wherein the roughness according to drying time is measured using an atomic force microscope (Atomic Force Microscope) , AFM).

The atomic force microscope is a type of scanning probe microscope (SPM) that uses a probe. Depending on the measurement method, these scanning probe microscopes are Scanning Tunneling Microscope (STM), Atomic Force Microscope (AFM), and Near-field Scanning Optical Microscope (Scanning Near-field Optical Microscope). It can be subdivided into so-called NSOM (SNOM), etc., and the roughness according to the drying time is preferably measured by an atomic force microscope.

The atomic force microscope is a third-generation microscope that can observe at thousands of times greater magnification than general optical and electron microscopes. It uses the force induced by the attractive and repulsive forces that change due to the gap or interaction between the pointed probe and the sample. Then observe the three-dimensional shape of the sample surface. The atomic force microscope has a micrometer-sized rod called a cantilever, at the end of which is a nanometer-sized probe. Use this probe to measure the height of the surface. More specifically, images such as topography are obtained using the van der Waals force that acts between the test sample and the probe. Atomic force microscopy can measure the height of a surface down to several nanometers or several angstroms, so it is possible to quantify roughness by accurately measuring topography images with small curvatures, such as the surface of a silicon wafer. Unlike the electron microscope, the atomic force microscope does not apply vacuum and does not require platinum coating, so the surface shape and roughness can be measured by repeatedly observing the coating film in the air over time.

Atomic force microscopy is used differently depending on the type of sample: contact mode, tapping mode, and non-contact mode, depending on whether the sample is in contact with the cantilever. First, in contact mode, the probe is in contact with the sample surface, enabling quick measurement, and is suitable for rough samples, so it can be used for friction analysis. However, soft samples have the disadvantage of being damaged or deformed. In tapping mode, the cantilever vibrates at a constant resonance period so that the probe has minimal contact with the sample surface, and measurement is made by changing the vibration frequency of the probe and cantilever. It can analyze easily damaged samples at high resolution and has the advantage of being suitable for analyzing biological samples. Lastly, in non-contact mode, the probe does not directly contact the sample surface, and van der Waals attraction acts between the probe and the sample surface. There is no direct contact with the sample, so the surface is not deformed and the cantilever has a long lifespan. In addition to the three basic modes of atomic force microscopy that measure the surface shape, magnetic force, electric force, friction force, etc. can be measured as an application mode that measures various characteristics, and a force-distance curve (FD) obtained by pressing a probe is used. Strength and elasticity analysis is possible using curves. In the force-distance curve, Force refers to the reaction force received when the cantilever presses the surface of the sample, and Distance refers to the deflection distance of the cantilever.

Roughness measured by atomic force microscopy can be obtained by obtaining a topographic image of the measurement area. Roughness refers to the height raised from the reference point when filling the depth of a lower valley from a height higher than the standard within a designated section. According to one embodiment of the present invention, the roughness according to the drying time is divided into Roughness Root Mean Square (Rrms) calculated by the root mean square and Roughness Average (Ra) calculated by the general arithmetic average method. ) is quantified by two parameters: While the surface shape that can be confirmed through a visual image is qualitative data and only relative comparison is possible, objective and quantitative information can be provided using the specific roughness value obtained by the present invention.

Meanwhile, the atomic force microscope and nano-indenter used to measure the physical properties of coating films in the present invention have the advantage of being able to measure a small sample area among analytical devices capable of precise measurement at the nanoscale, and can quickly measure the sample as is in an atmospheric environment. There is an advantage to having it. Quantitative data using official international units provides physical properties and allows additional observation of surface conditions.

According to one embodiment of the present invention, the method further includes comparing the measured value with one or more values of adhesion and hardness obtained by an existing measurement method. The step is a step of comparing the value measured through measuring one or more of adhesion and hardness according to the drying time with one or more values of adhesion and hardness obtained by an existing measurement method. Because it is checked whether the results match the results, the results of measuring the physical properties of the coating film can be evaluated as reliable and accurate. Existing measurement methods can be performed in the same environment as the quantitative measurement method of the present invention. The comparison step can be performed by determining the identity of the time when the degree of drying changes, as determined by measuring the drying time, and the time when the physical properties change.

In addition, the existing measurement method is a qualitative measurement method, and when the paint films being compared have similar physical properties, there is a problem in that the existing measurement method cannot distinguish and determine the difference. Accordingly, in order to improve this, the present inventors discovered a method that can objectively evaluate the properties of the coating film through a quantitative measurement method and at the same time accurately evaluate the physical properties of the coating film by comparing it with the existing measurement method in a complementary manner. The invention was completed. Through the present invention, the chemical composition of the coating film can be optimized and the physical properties for industrial applications can be improved.

According to one embodiment of the present invention, the adhesion according to the drying time is measured by one or more of an atomic force microscope (AFM) and a 90° peel test.

Details regarding the atomic force microscope are as described above, and the adhesion according to the drying time is preferably measured using an atomic force microscope among scanning probe microscopes.

The peel test is a test that measures the peeling force of a sample, and standards related to the peel test include ASTM D 3330, ASTM D 903, ASTM D1876, ISO 8510-2, ISO 1139, and KS T 1028. Depending on the peeling angle, it can be subdivided into 180°, 90°, T-Peel Strength, etc., and the adhesive strength according to the drying time is preferably measured by a 90° peel test.

According to one embodiment of the present invention, hardness according to the drying time is measured by a nano indenter.

The nano-indenter is a tester that measures the physical properties of the surface and surface layer of a coating film by nano-sized indentation. The tip is injected into the surface of a local sample with a small force, causing deformation of the test surface. It is a device for observing the degree of accuracy. The nano-indentation has the advantage of simple experimental preparation and process because it exhibits high resolution and analyzes the deformation behavior and characteristics of a local area on the surface of the specimen. The nano-indenter uses an indentation load-displacement curve (load-depth curve) obtained in the process of applying and removing the tip with a small nanometer-sized load to measure not only hardness and elastic modulus but also tensile properties and residual stress. Mechanical properties can be measured.

In the past, the pencil hardness test was widely used as a method of measuring the hardness of a coating film, but it was difficult to quantify hardness using this pencil hardness test. However, nano-indentation with high resolution enables in situ experiments to directly observe the deformation behavior of materials. Through this, the hardness of the coating film can be measured accurately and precisely.

According to one embodiment of the present invention, the adhesion results obtained by the existing measurement method are obtained by a cross-cut test. The cross-cut test is a method of making scratches in a grid of a certain width depending on the thickness of the coating film and then peeling off the coating film using tape. The standards related to the cross-cut test are ASTM D3359, KS M ISO 2409, etc. There is. The film pieces peeled off from the coating onto the tape are counted and the degree of adhesion is expressed as a value from 0B to 5B. In this way, the crosscut test is expressed in six levels of results from 0B to 5B (0B: when the separated surface exceeds 65% of the total area; 1B: when the separated surface exceeds 35% to 65% of the total area; 2B: When the separated surface is 15% to 35% of the total area; 3B: When the separated surface is 5% to 15% of the total area; 4B: When the separated surface is less than 5% of the total area; 5B: When the separated surface is less than 5% of the total area (if not present), the adhesive force can be expressed qualitatively. The present invention can accurately evaluate the physical properties of a coating film by comparing the above crosscut test with actually measured quantitative adhesion values.

According to one embodiment of the present invention, the hardness results obtained by the existing measurement method are obtained by a pencil hardness test. The pencil hardness test is performed by placing the lead of a pencil specified in KS G2603 (pencil) on the surface at an angle of 45° and scratching it while applying a certain load. Pencil hardness is expressed in descending order of hardness as 9H, 8H, 7H, 6H, 5H, 4H, 3H, 2H, H, F, HB, B, 2B, 3B, 4B, 5B, 6B, 7B, 8B. In this way, since the pencil hardness test is expressed in terms of the type of pencil lead, hardness can be expressed qualitatively. The present invention can accurately evaluate the physical properties of a coating film by comparing the above pencil hardness test with actually measured quantitative hardness measurements.

According to one embodiment of the present invention, when, as a result of the comparison, the measured value shows a similar tendency to a result obtained by a conventional measurement method, the step of evaluating the measured value as an accurate value is further included. The present invention can accurately evaluate the physical properties of a coating film by comparing the results obtained by the existing measurement method expressed qualitatively as above with the actually measured values.

If the measured value does not show a similar tendency to the value obtained by the existing measurement method, the results obtained by the existing measurement method can be matched by changing the conditions for measuring one or more of adhesion and hardness. This can be repeated until the measured value shows a similar trend to the value obtained by the existing measurement method.

According to one embodiment of the present invention, the paint is a lacquer liquid sample. Lacquer is a light brown essence obtained by scratching the bark of the lacquer tree and is a coating agent that has been used in Asia for a very long time. The cured lacquer liquid exhibits high aesthetic gloss and color, and has high durability such as high strength, high heat resistance, acid resistance, alkali resistance, chemical resistance, insulation, insect repellent, and moisture resistance, so it has been traditionally used as a natural paint for preservation.

Lacquer trees have different seeds depending on the region where they grow. There are six species of the Lacqueraceae family that contain usable lacquer: sumac grows naturally in Korea, China and Japan, sumac grows naturally in Vietnam and Taiwan, and Burmese lacquer grows mainly in Myanmar, Cambodia and Thailand. Depending on the species, the main ingredients that make up the lacquer solution are different. More specifically, the main ingredient in lacquer is urushiol, in lacquer trees, lacol, and in Myanmar, thithiol. Depending on the difference in the main ingredients, the physical properties of lacquer also appear differently. The other main ingredient of lacquer liquid is catechol, which contains 60 to 70%, and is a mixture of moisture, polysaccharides, glycoproteins, and the enzyme laccase, and the ratio of the ingredients changes depending on the production period or region.

Lacquer is mainly cured by room temperature and high humidity curing or high temperature and dry curing, and depending on the conditions, even paint films made from the same lacquer liquid have different physical properties. When cured at room temperature and high humidity, the lacquer solution hardens slowly in a high humidity environment as the laccase enzyme cross-polymerizes the catechol molecules through the oxidation effect with water vapor in the air. When drying and curing the lacquer solution at high temperature, moisture is completely evaporated through heating, and urushiol is polymerized by oxygen and dries at a rapid rate.

As lacquer dries, fine particles are formed in a dense state within the lacquer liquid coating film, polysaccharides form an outline on the surface, and polymerized urushiol is located inside the particles, suppressing the oxidation reaction of urushiol, which is easily oxidized. The particles on the surface primarily suppress the oxidation reaction, and even if the layer is weathered and lost, the particles that replace the damaged part of the layer immediately below have a reproducible restorative ability, allowing the lacquer film to maintain its durability even after a thousand years.

As such, the degree of dryness and physical properties of lacquer vary depending on the drying conditions and environment, so it is difficult to produce lacquer products with the same quality during the manufacturing process. In addition, there is little research on quantitatively and objectively evaluating and comparing the degree of drying of lacquer and the physical properties of dried lacquer. Accordingly, it is necessary to measure the physical properties of the coating film in quantitative values and evaluate them objectively and accurately. Accordingly, in order to improve this, the present inventors discovered a method that can objectively evaluate the properties of the coating film through a quantitative measurement method and at the same time accurately evaluate the physical properties of the coating film by comparing it with the existing measurement method in a complementary manner. The invention was completed. In addition, the present invention can accurately evaluate the physical properties of the coating film by comparing the results obtained by the existing measurement method expressed qualitatively as above with the actually measured values.

According to one embodiment of the present invention, the lacquer liquid may be a lacquer liquid of different types and origins from Korea, China, Japan, Vietnam, or Myanmar, or may be made using Dongbang Kashu, an industrial product of Kasyu, which is a similar lacquer liquid. there is. Additionally, a mixed lacquer solution prepared by mixing Korean and Myanmar lacquer at a ratio of 1:1 may have been used as a measurement sample. According to one embodiment of the present invention, the lacquer liquid from Korea, China, and Japan is a lacquer liquid collected from lacquer trees. The one from Vietnam can be a lacquer solution collected from the black sumac tree, the one from Myanmar can be from the Burmese sumac tree, and Kashuchil can be a lacquer solution collected from the cashew tree. According to one embodiment of the present invention, the lacquer solution is not limited to lacquer trees such as lacquer trees, sumac trees, Burmese sumac trees, and cashew trees, and may include other species of trees from which lacquer can be collected. According to one embodiment of the present invention, the lacquer tree used is not limited to trees growing naturally in Korea, China, Japan, Vietnam, and Myanmar, and may include other regions where it can grow naturally. According to one embodiment of the present invention, accurate physical properties can be evaluated by comparing the drying degree and physical properties according to the drying time of different lacquer solutions according to each production region.

{Example}

Hereinafter, the present invention will be described in detail through examples. However, the following examples are merely examples to aid the overall understanding of the present invention, and the content of the present invention is not limited to the following examples.

<Reference example> Preparation of lacquer liquid sample

As raw lacquer (unrefined lacquer tree essence), lacquer from Korea, China, Japan, Vietnam, and Myanmar was prepared. Korean lacquer was purchased from lacquer collector Mr. Kim Bu-no (Wonju, South Korea), and Chinese, Japanese, and Myanmar lacquer were obtained from Pyung Hwa Shell (Seoul, South Korea). vietnam Lacquer was obtained from the Vietnam-Korea Institute of Science and Technology (Hanoi, Vietnam). Dongbang Kashu, a similar lacquer liquid, was obtained from Dongbang Kashu Chil Industry Co., Ltd. (Korea).

In addition, blended lacquer was produced by uniformly mixing Korean lacquer and Myanmar lacquer sap in a 1:1 ratio (weight ratio). For samples for measuring drying time, a diluted solution was prepared by mixing lacquer sap and turpentine oil in a 2:1 ratio (weight ratio), and for other samples, a diluted solution was prepared by mixing lacquer sap with turpentine oil in a 1:1 ratio (weight ratio). did. The solvent, turpentine, was obtained from Pyung Hwa Shell (Seoul, South Korea).

<Test Example 1> Measurement of drying time of coating film

1. Preparation of lacquer film for measuring drying time

A glass bed for measuring drying time was prepared with a size of 350 × 100 × 3 mm, ultrasonic washed with acetone and ethanol for 20 minutes each, and then dried. The lacquer solution for measuring drying time (lacquer sap: turpentine = 2:1) prepared in the reference example above was applied three times with a brush to prepare a 6μm-thick coating film on the bed, and then measured using a drying time measuring meter (AB-3600, It was installed on TQC Sheen, Netherlands).

2. How to measure the drying time of a paint film

The drying time of the prepared lacquer liquid sample was measured using a drying time meter. Specifically, the drying time was measured according to the test method of ASTM D5895 at room temperature and a humidity of 85 RH%. The surface of the lacquer sample was continuously scratched using a steel needle, and the degree of dryness was judged based on the shape of the needle's trace. The degree of dryness was expressed as adhesive drying (DF), fixed drying (TF), and hardening drying (HD). The results are shown in Table 1. Hard drying (HD) refers to the time until the needle mark of the measuring instrument completely disappears from the film surface.

drying time 3h 5h 8h 10h 16h 20h 24h 36h 48h 3d 7d 14d Made in Korea DF DF DF TF (HD) HD HD HD HD HD HD HD made in china DF DF DF TF TF TF (HD) HD HD HD HD made in japan DF DF DF DF DF DF TF (HD) HD HD HD HD made in vietnam DF DF DF DF DF DF DF TF (HD) HD HD HD Made in Myanmar DF DF DF DF DF TF (HD) Touhou Kashu TF (HD) HD HD HD HD HD HD HD HD HD HD blending DF DF TF (HD) HD HD HD HD HD HD

3. Result of measuring drying time of paint film

From Table 1 above, it can be seen that the drying time varies depending on the production area of the lacquer. It was confirmed that Korean and Chinese lacquer liquids dried relatively quickly, and Myanmar lacquer dried the slowest, completing drying after two weeks. Dongbang Kashu, a similar lacquer liquid, dried rapidly within 5 hours, and the blended lacquer liquid, which is a mixture of Korean and Myanmar lacquer liquids, completed drying relatively more slowly than Korean lacquer liquid.

From the above results, it can be seen that although the drying time of the lacquer can be roughly determined with a drying time meter, it is difficult to accurately express the degree of drying in numerical values. In other words, by indicating the degree of drying according to the drying time, the drying time according to the production area can be confirmed and used as a reference to determine the standard time for measuring physical properties over time, but the exact degree of drying cannot be measured.

<Test Example 2> Measurement of surface shape and roughness of coating film

1. Preparation of lacquer film for measuring surface shape and roughness

A slide glass measuring 4 × 3 cm was prepared as a substrate for measuring surface shape and roughness, ultrasonic washed with acetone and ethanol for 20 minutes each, and then dried. The lacquer solution prepared in the reference example (lacquer sap: turpentine = 1:1) was applied three times with a brush on the substrate to prepare a coating film with a thickness of 2-3 μm. The prepared lacquer liquid samples were stored in a drying room maintained at room temperature and a humidity of 85 RH%.

2. Method of measuring surface shape and roughness of coating film

For the stored lacquer liquid samples, the surface shape of the coating film was measured in two and three dimensions using an atomic force microscope (XE-100, Park Systems, Suwon, Korea) in an area of 40 × 40 μm ² in non-contact mode. , Roughness was measured using two parameters: Roughness Root Mean Square (Rrms), which is calculated using the root mean square, and Roughness Average (Ra), which is calculated using the general arithmetic average method. Roughness values were obtained using XEI v.4.3.0 software (Park Systems, Suwon, Korea). The surface shape of the coating film is shown in Figure 2. The surface roughness of the coating film is shown in Table 2.

Roughness (nm) drying time 3d drying time 7d Drying time 21d Rrms Ra Rrms Ra Rrms Ra Made in Korea 267.1 211.8 247.8 201.3 242.3 188.1 made in china 136.3 105.2 129.0 101.3 144.3 110.9 made in japan 218.1 172.8 198.2 156.2 139.1 109.7 made in vietnam 331.4 262.3 254.1 206.0 197.5 155.5 Made in Myanmar 13.4 7.5 16.4 9.2 17.3 10.0 Touhou Kashu 14.2 8.4 14.0 7.36 19.2 10.1 blending 104.5 78.0 62.7 46.8 123.0 77.8

3. Surface shape and roughness measurement results of the coating film

Figure 2 is an image of the surface of a coating film according to an embodiment of the present invention measured using an atomic force microscope (AFM). As shown in Figure 2, the dry state of the surface shape of the coating film can be confirmed by checking the presence or absence of apparent surface curves or bubble marks. Because the surface shape is visual, objective and quantitative information can be provided using the roughness value, compared to only relative comparisons.

From Table 2 above, it can be confirmed through quantitative values that the roughness changes as drying progresses. As drying progressed, the overall roughness tended to decrease. In addition, the roughness value varies depending on the components of the lacquer depending on the production area, and in particular, it can be confirmed that the roughness of the Myanmar lacquer liquid is the lowest among the lacquer liquids. In addition, Dongbang Kashu, a similar lacquer liquid, was found to have a relatively smooth and even surface compared to other natural lacquer liquids.

<Test Example 3> Measurement of surface adhesion of coating film 1

1. Preparation of lacquer film for measuring surface adhesion

A slide glass measuring 4 × 3 cm was prepared as a substrate for measuring the adhesion of the coating film, washed ultrasonically with acetone and ethanol for 20 minutes each, and then dried. The lacquer solution prepared in the reference example (lacquer sap: turpentine = 1:1) was applied three times with a brush on the substrate to prepare a coating film with a thickness of 2-3 μm. The prepared lacquer liquid samples were stored in a drying room maintained at room temperature and a humidity of 85 RH%.

2. Method of measuring surface adhesion of coating film

For the stored lacquer liquid sample, an area of 40 × 40 μm ² was scanned using an atomic force microscope (XE-100, Park Systems, Suwon, Korea) using a non-contact mode using a round-type cantilever, SD-R30-NCH 10M (Nanosensors). , Switzerland) was used to apply a force of 2 μN. A force-distance curve was derived by pressing 16 points into a 4×4 square shape. In the force-distance curve, the indentation point was detected as the inflection point of the upper curve, Young's modulus was calculated as the slope of the upper curve up to the indentation, and adhesive force was calculated as the curve area of the lower curve in the force-distance curve. Among the 16 points measured, the remaining values, excluding the minimum and maximum values, were averaged to quantitatively show the change in adhesion according to drying time while drying for 1 day, 3 days, 7 days, 14 days, 21 days, and 28 days. The force-distance curve shown by measuring the surface of the coating film using an atomic force microscope is shown in Figure 3. The adhesion of the coating film is shown in Table 3. The Young's modulus of the coating film is shown in Table 4.

Adhesion (J×10 ¹⁵ ) Drying time (days) One 3 7 14 21 28 Made in Korea 48.9 14.7 8.2 6.0 5.2 3.0 made in china 13.4 4.4 2.6 0.8 0.5 0.9 made in japan 65.3 23.3 0.7 0.4 0.3 0.2 made in vietnam 141.7 45.2 36.1 26.1 12.8 2.9 Made in Myanmar - 1662.1 531.8 271.3 43.9 56.0 Touhou Kashu 4.9 4.2 3.4 2.2 4.2 4.0 blending 41.8 29.9 5.05 4.4 1.9 1.6

Young's modulus (GPa) Drying time (days) One 3 7 14 21 28 Made in Korea 76.5 236.6 348.1 453.7 496.2 1325.2 made in china 120.1 340.2 416.3 570.1 657.3 1651.4 made in japan 94.5 232.5 358.8 498.1 642.5 1483.9 made in vietnam 61.0 141.6 187.9 258.9 336.2 884.9 Made in Myanmar - 16.3 27.0 39.1 102.0 105.6 Touhou Kashu 159.6 373.7 426.1 444.4 985.9 1315.0 blending 72.2 115.2 175.9 271.7 679.3 765.6

3. Result of measuring surface adhesion of coating film

Figure 3 is a force-distance curve graph showing the surface of a coating film according to an embodiment of the present invention measured by an atomic force microscope (AFM). As shown in Figure 3, the force-distance curve showing the adhesive force of lacquer shows a rapid change depending on the production area at a specific drying time, showing that the surface adhesion varies greatly depending on the production area of the lacquer. Additionally, from Tables 3 and 4, it can be seen that the adhesion decreases and Young's modulus increases as drying time passes, and that both adhesion and Young's modulus undergo rapid fluctuations in the same time period.

<Test Example 4> Measurement of adhesion between substrate and lacquer film 2

1. Preparation of lacquer film for measuring adhesion

As a substrate for measuring the adhesion of the coating film, a glass slide glass and stainless steel measuring 8 × 3 cm were prepared, ultrasonic washed with acetone and ethanol for 20 minutes each, and then dried. The lacquer solution prepared in the reference example (lacquer sap: turpentine = 1:1) was applied three times with a brush on the substrate to prepare a coating film with a thickness of 2-3 μm. The prepared lacquer liquid samples were stored in a drying room maintained at room temperature and a humidity of 85 RH%.

2. Method of measuring adhesion between substrate and lacquer film

For the stored lacquer liquid samples, the interfacial adhesion between the substrate and the lacquer liquid was confirmed using a 90° peel tester (KOPC-B, Kyungjin Hitex, Korea). More specifically, after attaching the tape to the sample with a 90° peel tester, the tape was pulled in a direction of 90° at a speed of 400 mm/min with a load cell of 10 kgf. The tape was a 10 mm wide product made of polyethylene terephthalate film coated with acrylic adhesive. The lacquer liquid film was peeled from the substrate using a tape, and the force applied at that time was measured. Measurements were performed by measuring at least three times on the same substrate and averaging them. The results are shown in Table 5.

Adhesion (N/m) glass stainless steel Drying time 7 days Drying time 10 days Drying time 7 days Drying time 10 days Made in Korea 12.0 12.1 24.2 19.2 Made in Myanmar 5.2 3.9 4.7 5.9 Touhou Kashu 3.5 5.2 15.2 16.0 blending 5.6 4.8 4.31 5.1

3. Result of measuring adhesion of coating film

From Table 5, the adhesive strength tended to decrease as drying progressed for the glass substrate, but the value tended to increase as drying progressed for the stainless steel substrate. Slowly drying Myanmar products showed changes in adhesion, while rapid drying Dongbang Kashu showed relatively constant adhesion. It can be seen that the adhesive strength shows different aspects depending on the type and production area of the substrate, and it can be seen that minute changes can be measured quantitatively.

<Test Example 5> Measurement of hardness of coating film

1. Preparation of lacquer film for hardness measurement

A slide glass measuring 4 × 3 cm was prepared as a base for measuring the hardness of the coating film, ultrasonic washed with acetone and ethanol for 20 minutes each, and then dried. The lacquer solution prepared in the reference example (lacquer sap: turpentine = 1:1) was applied three times with a brush on the substrate to prepare a coating film with a thickness of 2-3 μm. The prepared lacquer liquid samples were stored in a drying room maintained at room temperature and a humidity of 85 RH%.

2. Method of measuring hardness of coating film

The hardness of the stored lacquer liquid samples was measured using a nano-indenter with a Berkovich diamond tip (TI 950, Bruker, USA). More specifically, the sample surface was repeatedly injected 9 times with a force of 2 mN, and an indentation load-displacement curve was derived. While drying for 1 day, 3 days, 7 days, 14 days, 21 days, and 28 days, the change in hardness according to drying time was quantitatively shown from the indentation load-displacement curve. The hardness of the coating film is shown in Table 6.

Hardness (GPa) Drying time (days) One 3 7 14 21 28 Made in Korea 0.14 0.20 0.23 0.33 0.32 0.28 made in china 0.19 0.20 0.22 0.34 0.32 0.26 made in japan 0.06 0.09 0.14 0.24 0.23 0.32 made in vietnam 0.02 0.09 0.10 0.17 0.22 0.16 Made in Myanmar - - 0.02 0.02 0.02 0.02 Touhou Kashu 0.19 0.21 0.21 0.21 0.22 0.20 blending 0.07 0.12 0.12 0.13 0.16 0.15

3. Result of hardness measurement of coating film

Figure 4 is an indentation load-displacement curve graph showing the surface of a coating film according to an embodiment of the present invention measured by a nano indenter. As shown in Figure 4 and Table 6, it can be seen that the hardness value increases as drying progresses, and when the change in value is stagnant, it can be seen that this is because it is in a completely dried state. In addition, there are differences in hardness depending on the production area, with the lacquer film from Myanmar having the weakest hardness, followed by those from Korea and China. It was found that the hardness of the Japanese lacquer film was relatively high. Dongbangkashu, a synthetic paint, was found to have a stronger hardness than lacquer from Myanmar, although it is weaker than the lacquer liquid from the Japanese lacquer tree.

<Test Example 6> Confirmation of adhesion pattern of coating film

1. Preparation of lacquer film to confirm adhesion pattern

As a substrate to check the adhesive strength of the coating film, stainless steel measuring 8 × 3 cm was prepared, ultrasonic washed with acetone and ethanol for 20 minutes each, and then dried. The lacquer solution prepared in the reference example (lacquer sap: turpentine = 1:1) was applied three times with a brush on the substrate to prepare a coating film with a thickness of 2-3 μm. The prepared lacquer liquid samples were stored in a drying room maintained at room temperature and a humidity of 85 RH%.

2. How to check the adhesion pattern of the coating film

The adhesion of the stored lacquer liquid samples was measured according to the cross-cut test method of ASTM D3359. More specifically, scratches were made on the surface of the sample in the form of a checkerboard using knives with 2 mm intervals in a crosscut tester (YCC-230/1, Yoshimitsu, Japan). Afterwards, the adhesive strength of the sample was checked according to the degree to which the surface film fell off while attaching and removing the tape. Adhesion is expressed in stages from 0B to 5B, with 0B meaning the weakest adhesion with all the film removed after the test, and 5B meaning the strongest adhesion with the film intact after the test. The results are shown in Table 7.

adhesion Drying time (days) 7 10 Made in Korea 4B 4B made in vietnam 3B 3B Made in Myanmar 0B 0B Touhou Kashu 0B 0B blending 2B 2B

3. Confirmation results of the adhesion pattern of the coating film

As shown in Table 7, it was confirmed that the peeling strength varies depending on the origin, drying time, and production area of the lacquer solution, but it can be seen that accurate values for adhesive strength cannot be obtained using such existing measurement methods.

<Test Example 7> Confirmation of hardness pattern of coating film

1. Preparation of lacquer film to confirm hardness pattern

A slide glass measuring 4 × 3 cm was prepared as a base for measuring the hardness of the coating film, ultrasonic washed with acetone and ethanol for 20 minutes each, and then dried. The lacquer solution prepared in the reference example (lacquer sap: turpentine = 1:1) was applied three times with a brush on the substrate to prepare a coating film with a thickness of 2-3 μm. The prepared lacquer liquid samples were stored in a drying room maintained at room temperature and a humidity of 85 RH%.

2. How to check the hardness of the coating film

The pencil hardness of the stored lacquer liquid sample was measured according to the pencil hardness test method of ASTM D3363. More specifically, the presence or absence of scratches was confirmed by scratching the surface of the sample with a Mitsubishi ‘UNI’ grade pencil under a load of 1kgf using a pencil hardness meter (221-D, Kibae E&T, Korea). Pencil hardness was expressed in descending order of hardness as 9H, 8H, 7H, 6H, 5H, 4H, 3H, 2H, H, F, HB, B, 2B, 3B, 4B, 5B, 6B. Measurements were repeated three or more times and averaged. The results are shown in Table 8.

adhesion Drying time (days) 3 7 21 Made in Korea 3H 3H 4H made in china 4H 4H 3H made in japan 4H 4H 4H made in vietnam 2B F 4H Made in Myanmar 4B B 2B Touhou Kashu 3H 2H 3H blending B 3H H

3. Confirmation results of the hardness pattern of the coating film

As shown in Table 8, it was confirmed that the pencil hardness increases or is maintained depending on the origin, drying time, and production area of the lacquer liquid, but it can be seen that accurate values for hardness cannot be obtained with such existing measurement methods.

<Test Example 8> Comparison of coating film adhesion measurement results and coating film adhesion aspects

The adhesion pattern of the coating film confirmed through the crosscut test in <Test Example 6> was compared with the adhesion value of the coating film measured using an atomic force microscope and a 90° peel tester in <Test Example 3> and <Test Example 4>. As a result of the above comparison, both qualitative aspects and quantitative measurements indicated that the adhesive force was similar or decreased as drying time passed. Through this, the quantitative measurement value can be evaluated as accurate.

<Test Example 9> Comparison of hardness measurement results and hardness patterns of coating films

The hardness pattern of the coating film confirmed through the pencil hardness test in <Test Example 7> was compared with the hardness value of the coating film measured with a nano-indenter in <Test Example 5>. As a result of the above comparison, both qualitative aspects and quantitative measurements indicated that hardness increased with drying time. Through this, the quantitative measurement value can be evaluated as accurate.

<Test Example 10> Measurement and confirmation of the adhesion and hardness of the coating film according to dry state

1. Test method

In the same manner as in <Test Example 1> to <Test Example 7>, the drying time, adhesion, and hardness of the coating film were measured and their patterns were confirmed. The results for the fixed dry state are shown in Table 9. The results for the cured dry state are shown in Table 10.

division drying time pencil hardness Nano-Indenter Hardness
(GPa) Atomic Force Microscope Adhesion
(J×10 ¹⁵ ) 90° Peel Tester Adhesion
(N/m) Made in Korea 10h Not measured 0.08 48.96 Not measured made in china 16h Not measured 0.06 14.8 Not measured made in japan 24h Not measured 0.09 65.33 Not measured made in vietnam 36h Not measured 0.02 59.4 Not measured Made in Myanmar 7d 4B 0.07 271.28 4.70 Touhou Kashu 3h Not measured 0.09 10.28 Not measured blending 35h Not measured 0.07 41.79 Not measured

division drying time pencil hardness Nano-Indenter Hardness
(GPa) Atomic Force Microscope Adhesion
(J×10 ¹⁵ ) 90° Peel Tester Adhesion
(N/m) Made in Korea 10h 3H 0.23 14.70 19.21 made in china 16h 4H 0.22 13.42 Not measured made in japan 24h 4H 0.19 16.3 Not measured made in vietnam 36h 2B 0.16 26.1 Not measured Made in Myanmar 7d B 0.10 43.9 5.088 Touhou Kashu 3h 4H 0.20 4.8 15.97 blending 35h 3H 0.16 29.88 5.10

As shown in Table 9 and Table 10, the drying time of the Korean lacquer liquid was the fastest, and the Chinese and Japanese lacquer liquids also showed similar drying times. Myanmar lacquer dried at the slowest rate, while Dongbang Kashu, a similar lacquer, dried the fastest and most rapidly. The drying time of the blended lacquer, which was a uniform mixture of Korean lacquer and Myanmar lacquer sap at a 1:1 ratio (weight ratio), was slower than Korean lacquer and much faster than Myanmar lacquer. The hardness of the blended lacquer was tested using a pencil hardness and showed a hardness similar to that of Korean products. Although the pencil hardness measurement showed similar hardness, the nanoindenter measurement results showed that the Korean lacquer film had a higher hardness value, so it was possible to accurately compare and measure it. Through this, using the evaluation method of the present invention, it is possible to find the optimal desired physical properties by adjusting the mixing and drying time and changing hardness and adhesion and utilize it in industry.

Although exemplary embodiments of the present invention have been described above in relation to the above-mentioned preferred embodiments, various modifications and variations can be made without departing from the gist and scope of the invention. Accordingly, the appended claims will include such modifications and variations as long as they fall within the spirit of the present invention.

Claims (9)

Measuring the drying time for the coating film formed by the paint applied on the substrate;
It includes; measuring one or more of adhesion and hardness according to drying time,
It further includes measuring roughness according to drying time,
The roughness according to the drying time is measured by an atomic force microscope (AFM),
A method for evaluating coating film properties, wherein the adhesion according to the drying time is measured by one or more of an atomic force microscope (AFM) and a 90° peel test. According to paragraph 1,
Comparing the measured value with one or more results of adhesion and hardness obtained by an existing measurement method. A method for evaluating coating film properties, further comprising: According to paragraph 1,
A method for evaluating the physical properties of a coating film, wherein the hardness according to the drying time is measured by a nano indenter. According to paragraph 2,
A method for evaluating coating film properties, wherein the adhesion results obtained by the existing measurement method are obtained by a cross-cut test. According to paragraph 2,
A method for evaluating coating film physical properties, wherein the hardness results obtained by the existing measurement method are obtained by a pencil hardness test. According to paragraph 2,
As a result of the comparison, if the measured value shows a similar tendency to the result obtained by the existing measurement method, evaluating the measured value as an accurate value. A method for evaluating coating film properties, further comprising: According to paragraph 1,
A method for evaluating the physical properties of a coating film, wherein the paint is a lacquer liquid sample. delete delete