Screen printing color ink color detection method

Abstract

The invention provides a screen printing color ink color detection method. The method comprises the following steps that a screen printing plate with the same mesh number as actual printing is manufactured; different batches of to-be-detected silk-screen color ink are used as comparison ink, the comparison ink and the standard ink have the same color, the standard ink and the comparison ink are subjected to sample scraping and color showing on coated paper through a screen printing plate at the same time, and a standard sample and a comparison sample for detection are prepared; fully curing the standard sample and the comparison sample through ultraviolet light under the same condition; sampling the cured standard sample and the comparison sample, analyzing and calculating through a CLELab model to obtain color difference data of the standard sample and the comparison sample, and representing a color detection result by using the obtained color difference data; and comparing whether the color difference data of the standard sample and the comparison sample is within a preset range, and judging whether the comparison ink is qualified. Influences of subjective factors can be greatly reduced, the accuracy of detection results is effectively improved, the quality of color ink is accurately controlled, the printing effect is effectively improved, and the quality of printed products is guaranteed.

Description

Technical Field

[0001] The invention relates to the field of screen printing, and in particular to a method for detecting the color of screen printing ink. Background Art

[0002] Screen printing refers to using a silk screen as a base and making a screen plate with images through a photosensitive platemaking method. Screen printing consists of five major elements: screen plate, scraper, ink, printing table and substrate. Printing is based on the basic principle that the mesh holes of the image part of the screen plate can pass the ink, while the mesh holes of the non-image part cannot pass the ink. When printing, pour ink on one end of the screen plate, use a scraper to apply a certain pressure to the ink part on the screen plate, and move at a constant speed toward the other end of the screen plate. During the movement, the ink is squeezed from the mesh holes of the image part to the substrate by the scraper.

[0003] The existing UV-curable screen printing ink color detection method mainly relies on visual comparison observation. When evaluating small-area line patterns, this method, although there is a color difference with the standard ink, is usually not obvious after screen printing due to the small pattern area, so the printed products are generally acceptable. However, for patterns or texts with larger template opening areas, the impact of color differences becomes very obvious after screen printing due to the increase in pattern area. In addition, because the determination of the ink submitted for inspection does not take into account the acceptance of screen printing of different areas, the application effect of the same ink on products of different areas cannot be determined in advance and must be verified through actual printing on the machine. In addition, the viscosity characteristics of screen printing ink are between gravure ink and offset ink. Since there is no ready-made color ink detection method for reference, the complexity of detection is increased. It is difficult to ensure the consistency of the detection results with the actual printing results by visual comparison by technicians alone.

[0004] Therefore, there is an urgent need to provide a method for detecting the color of screen printing ink to improve the accuracy of the color ink detection result and improve the printing quality. Summary of the invention

[0005] In view of the shortcomings of the prior art described above, the technical problem to be solved by the present invention is to provide a method for detecting the color of silk screen ink to reduce the influence of human subjective factors on the accuracy of silk screen ink detection results, while achieving accurate detection of color differences between different batches of silk screen ink.

[0006] The present invention provides a method for detecting the color of screen printing ink, comprising the following steps:

[0007] S100, make a screen with the same mesh number as the actual printing;

[0008] S200, using a different batch of screen printing ink to be tested as a comparison ink, and the comparison ink is the same color as the standard ink, and the standard ink and the comparison ink are simultaneously scraped and color-developed on coated paper through the screen under the same conditions to prepare a standard sample and a comparison sample for testing;

[0009] S300, fully curing the standard sample and the comparison sample by ultraviolet light under the same conditions;

[0010] S400, sampling the cured standard sample and the comparison sample, obtaining color difference data of the two by CLELab model analysis and calculation, and characterizing the color detection result by using the obtained color difference data;

[0011] S500, comparing the color difference data of the standard sample and the comparison sample to see whether they are within a preset range. If the color difference data is within the preset range, the quality of the batch of ink meets the requirements; if the color difference data is not within the preset range, the quality of the batch of ink does not meet the requirements.

[0012] Preferably, in step S200, before the sample is scraped and the color is developed, the standard ink and the comparison ink need to be stirred evenly and left to stand until the bubbles completely disappear.

[0013] Preferably, in step S200, during the process of scraping and color development, a uniform and equal pressure is applied to the printing surface by a scraper, and the scraper and the printing surface are inclined, wherein the inclination angle is preferably 20° to 70°.

[0014] Preferably, in step S300, the standard sample and the comparison sample are placed in the same ambient temperature so that both reach the same temperature, preferably 21°C to 25°C.

[0015] Preferably, in step S300, the standard sample and the comparison sample are cured by UV drying equipment, and the ultraviolet light energy value is 80mj / cm 2 ~84mj / cm 2 .

[0016] Preferably, the step S400 includes, when sampling, measuring multiple points from the color development area of ​​the cured standard sample to obtain the corresponding average values ​​of the L value, a value and b value of the standard sample, measuring multiple points from the color development area of ​​the cured comparison sample to obtain the corresponding average values ​​of the L value, a value and b value of the comparison sample, and obtaining the color difference data of the standard sample and the comparison sample, i.e., the CIEΔE value, by calculation.

[0017] Preferably, in step S500, the acceptable range of the color difference between the standard sample and the comparison sample is preferably 0-2.

[0018] As described above, the present invention relates to a method for detecting the color of a screen printing ink, which has the following beneficial effects:

[0019] The present invention manufactures a screen with the same mesh number as the actual printing, and simultaneously scrapes and solidifies the standard ink and the comparison ink on the screen, and respectively obtains the color difference data of the standard ink and the comparison ink through sampling, analysis, calculation and other processes. The color difference data can be used to visually check the color difference of different batches of silk screen color ink, greatly reduce the influence of subjective factors, and effectively improve the accuracy of the test results. The present invention can also realize accurate control of the color ink quality through the color difference data, thereby effectively improving the printing effect and ensuring the quality of the printed product. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic flow chart of a method for detecting color of screen printing ink provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0021] The following is a description of the implementation of the present invention by means of specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0022] It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change of the proportion relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and so on quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. The change or adjustment of the relative relationship should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0023] It should be noted that CIELab is the most complete color model commonly used to describe all colors visible to the human eye. It was proposed by the International Commission on Illumination (the initials of the Commission International ed'Eclairage are CIE) for this special purpose. Because the red / green and yellow / blue opposing channels are calculated as the difference of the transformation of the (assumed) cone cell response similar to the Munsell value, CIELab is an Adams color value (Chromatic Value) space. The three basic coordinates of L value, a value and b value represent the brightness of the color (L = 0 generates black and L = 100 indicates white), its position between red / magenta and green (a negative value indicates green and positive value indicates magenta) and its position between yellow and blue (b negative value indicates blue and positive value indicates yellow). The established Lab color model serves as a device-independent model used as a reference.

[0024] like Figure 1 As shown, an embodiment of a method for detecting the color of a silk screen ink comprises the following steps:

[0025] S100, make a screen with the same mesh number as the actual printing. Specifically, according to the actual printing needs, select a suitable screen material, such as polyester mesh, the mesh number of which is preferably 200 mesh, the screen size is preferably 30cm×24cm, the frame height is preferably 2cm, the thickness is preferably 3cm, and the basic tension of the screen is preferably. At least two parallel patterns are provided on the screen, and the pattern includes but is not limited to rectangles, and can also be other shapes such as circles, squares, diamonds, etc. The number of screen patterns in this embodiment is preferably two, that is, one pattern is used for standard ink scraping and color development, and the other is used for comparison ink. In addition, this embodiment can also set a plurality of identical patterns, and each pattern is arranged in a linear array, the pattern at one end of the array is used for standard ink scraping and color development, and the remaining patterns are used for a variety of different batches of comparison inks, so as to facilitate one-time detection of different batches of ink to be detected.

[0026] S200, prepare standard ink and at least one screen printing ink from a different batch, use the screen printing ink from a different batch to be tested as the comparison ink, and the comparison ink is the same color as the standard ink, stir the standard ink and the comparison ink evenly, let it stand for a while, and wait for the bubbles to completely disappear. Then, the operator will ink the standard ink and the comparison ink in the screen, and use a scraper to scrape the standard ink and the comparison ink on the coated paper through the screen at the same time under the same conditions. The coated paper is preferably double-sided coated paper, and the grammage is preferably 140g / m 2 -160g / m 2. During the scraping and color development process, the operator uses a scraper to scrape along the rectangular pattern from top to bottom to make standard samples and comparison samples for testing. It should be noted that when scraping, the operator applies uniform and equal pressure to the printed surface through the scraper, and the scraper is inclined to the printed surface, and the inclination angle is preferably 20°~70°, to ensure that the standard ink and the comparison ink have the same scraping and color development effect under the same conditions. Among them, the scraper hardness requirement is preferably 70HA~75HA; the length of the scraper exceeding the screen pattern is preferably 2cm~10cm to ensure that there is no deformation on both sides of the scraper to avoid uneven ink coating during scraping; the edge of the scraper is polished to avoid scratches on the surface of the photosensitive film in the ink due to sharp corners.

[0027] S300, the operator places the standard sample and the comparison sample in the ultraviolet drying equipment for curing. During the curing process, the standard sample and the comparison sample are in the same ambient temperature and in the same constant temperature state, so that the two reach the same temperature, preferably 21°C to 25°C; the ultraviolet energy value is preferably 80mj / cm 2 ~84mj / cm 2 , to ensure that the standard samples and comparison samples can be fully solidified.

[0028] S400, sampling the cured standard sample and the comparison sample. When sampling, multiple points are taken in the middle of the color development area of ​​the standard sample and measured. When measuring, a d / 8° (i.e., diffuse reflection 8°) integrating sphere spectrophotometer is used. Under the conditions of D65 / 10° (D is the light source, 10° refers to the viewing angle) and including specular reflection, the L value, a value and b value of each sampling point are measured by the spectrophotometer, and the average value of the three values ​​is calculated to obtain the L0 value, a0 value and b0 value; multiple points are taken at any position in the middle area of ​​the color development area of ​​the comparison sample and measured, the L value, a value and b value of each sampling point are measured by the spectrophotometer, and the average value of the three values ​​is calculated to obtain the L1 value, a1 value and b1 value. The color difference data of the standard sample and the comparison sample are calculated by the CIELab model, that is, ΔL=L1-L0, Δa=a1-a0, Δb=b1-b0. The color difference data of the standard sample and the comparison sample are calculated according to ΔL, Δa and Δb, that is, the CIE ΔE value, as shown in formula (1):

[0029]

[0030] The CIE △E value was rounded to 0.01, and the obtained CIE △E value was used to characterize the ink color test results.

[0031] S500, by comparing the color difference data (i.e., CIE△E value) of the standard sample and the comparison sample obtained in step S400, whether they are within the preset range, and judging whether the comparison sample meets the requirements. Among them, the qualified range of the color difference between the standard sample and the comparison sample is preferably 0-2.00. If the obtained CIE△E value is ≤2.00, the quality of the batch of ink meets the requirements; if the obtained CIE△E value is greater than 2.00, the quality of the batch of ink does not meet the requirements, and the comparison ink has quality problems, thereby completing the accurate detection of the color of the silk screen ink.

[0032] The present invention can visually inspect the color difference of different batches of silk-screen ink, greatly reduce the influence of subjective factors, effectively improve the accuracy of the test results, realize precise control of the ink quality, and thus effectively improve the printing effect and ensure the quality of the printed products.

[0033] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for detecting the color of screen printing ink, characterized in that: The following steps are involved: S100, make a screen with the same mesh number as the actual printing; S200, using a different batch of screen printing ink to be tested as a comparison ink, and the comparison ink is the same color as the standard ink, and the standard ink and the comparison ink are simultaneously scraped and color-developed on coated paper through the screen under the same conditions to prepare a standard sample and a comparison sample for testing; S300, fully curing the standard sample and the comparison sample by ultraviolet light under the same conditions; S400, sampling the cured standard sample and the comparison sample, obtaining color difference data of the two by CLELab model calculation, and characterizing the color detection result by using the obtained color difference data; S500, comparing the color difference data of the standard sample and the comparison sample to see whether they are within a preset range. If the color difference data is within the preset range, the quality of the batch of ink meets the requirements; if the color difference data is not within the preset range, the quality of the batch of ink does not meet the requirements.

2. The method for detecting the color of screen printing ink according to claim 1, characterized in that: In the step S200, before the sample is scraped and the color is developed, the standard ink and the comparison ink need to be stirred evenly and left to stand until the bubbles completely disappear.

3. The method for detecting the color of screen printing ink according to claim 1 or 2, characterized in that: In the step S200, during the process of scraping and color development, a uniform and equal pressure is applied to the printing surface by a scraper, and the scraper and the printing surface are inclined, wherein the inclination angle is preferably 20° to 70°.

4. The method for detecting the color of screen printing ink according to claim 1, characterized in that: In the step S300, the standard sample and the comparison sample are placed in the same ambient temperature so that both reach the same temperature, preferably 21°C to 25°C.

5. The method for detecting the color of screen printing ink according to claim 1 or 4, characterized in that: In step S300, the standard sample and the comparison sample are cured by ultraviolet drying equipment, and the ultraviolet energy value is 80mj / cm 2 ~84mj / cm 2 .

6. The method for detecting the color of screen printing ink according to claim 1, characterized in that: The step S400 includes, when sampling, measuring multiple points from the color development area of ​​the cured standard sample to obtain the corresponding average values ​​of the L value, a value and b value of the standard sample, measuring multiple points from the color development area of ​​the cured comparison sample to obtain the corresponding average values ​​of the L value, a value and b value of the comparison sample, and obtaining the color difference data of the standard sample and the comparison sample, i.e., the CIE ΔE value, by calculation.

7. The method for detecting the color of screen printing ink according to claim 1, characterized in that: In step S500, the acceptable range of the color difference between the standard sample and the comparison sample is preferably 0-2.

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