PRINTED BOARD

Abstract

A printed board, a screen-printing ink, and a screen-printing method are provided. The printed board comprises a printed pattern and/or printed line which comprises a polymer binder and a fluorine-based surfactant, has excellent thickness uniformity and straightness, has no edge top defect, and is not damaged even when formed on a repeatedly folded substrate.

Claims

1. A printed board; comprising: a substrate; and a printed pattern formed on the substrate, wherein the printed pattern comprises one or more printed lines, wherein the printed line comprises a polymer binder and a fluorine-based surfactant, and wherein the printed line has thickness uniformity, a difference between the maximum thickness and the minimum thickness, of 0.6 μm or less and an edge top deviation, an absolute value of a difference between an average thickness of the printed line and thickness of an edge portion of the printed line having the average thickness, of 0.55 μm or less.

2. The printed board according to claim 1, wherein the printed line has a thickness in a range of 0.5 μm to 10 μm.

3. The printed board according to claim 1, wherein the printed line has straightness of 50 μm or less, wherein the straightness is obtained by analyzing an image measured with an optical microscope.

4. The printed board according to claim 1, wherein the printed pattern is a bezel pattern.

5. The printed board according to claim 1, wherein in the printed line, the polymer binder is comprised in an amount of 50 to 95 weight %, and the fluorine-based surfactant is comprised in an amount of 0.25 to 2.5 parts by weight relative to 100 parts by weight of the polymer binder.

6. A screen-printing ink comprising: a polymer binder; and a fluorine-based surfactant, wherein the polymer binder is comprised in an amount of 20 to 40 weight %, and wherein the fluorine-based surfactant is comprised in an amount of 0.25 to 2.5 parts by weight relative to 100 parts by weight of the polymer binder.

7. The screen-printing ink according to claim 6, wherein the polymer binder is one or more selected from the group consisting of polyesters, urethane-modified polyesters, epoxy-modified polyesters, acrylic-modified polyesters, vinyl chloride-vinyl acetate copolymer resins, butyral resins, polyether urethane resins, polyester urethane resins, polycarbonate urethane resins, epoxy resins, phenol resins, acrylic resins, polyamide resins, polyamideimide resins, polyolefin resins, chlorinated polyolefin resins, chlorinated rubbers, melamine resins, urea resins, ethyl cellulose resins, nitrocellulose resins, cellulose acetate butyrate, cellulose acetate propionate, rosin resins, maleic acid resins, natural resins and alkyd resins.

8. The screen-printing ink according to claim 6, wherein the fluorine-based surfactant is a nonionic surfactant.

9. The screen-printing ink according to claim 6, further comprising 20 to 90 parts by weight of a pigment or dye relative to 100 parts by weight of the polymer binder.

10. The screen-printing ink according to claim 6, further comprising 100 to 300 parts by weight of a compound of Formula 1 relative to 100 parts by weight of the polymer binder: ##STR00002## wherein; R.sub.1 is a hydrogen atom, an alkyl group or an alkylcarbonyl group, L.sub.1 is an alkylene group, R.sub.2 is an alkyl group or a hydrogen atom, and n is a number within a range of 1 to 10.

11. The screen-printing ink according to claim 10, wherein a content of the compound of Formula 1 is less than 70 weight %.

12. A screen-printing method, comprising transferring the screen-printing ink of claim 6 to a substrate to be printed through a screen-printing plate.

13. The screen-printing method according to claim 12, wherein printing speed is controlled to be from 20 to 200 mm/sec.

14. The screen-printing method according to claim 12, wherein printing speed is controlled such that S value of Equation 1 is in a range of 25 to 110:
S=R×W  [Equation 1] wherein R is the printing speed, and W is parts by weight of the fluorine-based surfactant relative to 100 parts by weight of the polymer binder in the ink.

15. The screen-printing method according to claim 12, wherein a bezel pattern is formed on the substrate to be printed.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0089] FIG. 1 is a diagram illustrating an exemplary bezel pattern of an embodiment of the present disclosure.

[0090] FIG. 2 is a diagram showing a laminated structure of a printed board according to an embodiment of the present disclosure.

[0091] FIG. 3 is a diagram showing a sample specimen for measuring a thickness of a printed pattern.

[0092] FIG. 4 is a graph showing an example of a thickness profile.

[0093] FIG. 5 is a diagram showing a folded portion in a folding test.

[0094] FIG. 6 is an optical microscope image of a printed pattern after a folding test.

DESCRIPTION OF REFERENCE NUMERALS

[0095] 100: cover substrate [0096] 200: pressure-sensitive adhesive layer or adhesive layer [0097] 300: printed pattern [0098] 400: substrate

DETAILED DESCRIPTION

[0099] Hereinafter, the present application will be described in detail through Examples, but the scope of the present application is not limited by Examples below.

[0100] Method of Measuring Print Thickness and Edge Top

[0101] A thickness of a printed pattern as screen-printed was evaluated using Alphastep Profiler (KLA Tencor D-300) (Conditions: Contact force 5 μg, Scan speed: 100 μm/sec). As shown in FIG. 3, a polymer film (400) comprising a screen-printed pattern (300) was laminated on a glass (10) using the OCA (20) so that distortion of the printed pattern thickness did not occur, and then the thickness was evaluated in the longitudinal direction of the printed pattern.

[0102] When the thickness of the printed pattern is measured in the above manner, thickness data as shown in FIG. 4 can be obtained (in FIG. 4, the x-axis is the measurement position of the thickness, and the y-axis is the thickness). In the data, the average value of the central thickness region (2000) excluding the left and right sides was designated as the printing thickness, and the thickness uniformity (the difference between the maximum thickness and the minimum thickness) through the difference between the maximum and minimum values in the central thickness region (2000) was confirmed.

[0103] In addition, the occurrence of edge top defects was evaluated by confirming the absolute value (edge top deviation) of the difference between the higher height (the height of 1000 in FIG. 4) of the heights of the left and right sides in the thickness shape data and the average value as the printing thickness.

[0104] The average value of the central thickness region (2000), the thickness uniformity, and the edge top deviation were evaluated for the four printed lines (printed line from I to II, printed line from II to III, printed line from III to IV, and printed line from IV to I in FIG. 1), respectively. As a result, the average value of the central thickness region (2000) was described as the average value of the results for the four printed lines, and the thickness uniformity and edge top deviation were described as the worst results among the results for the four printed lines in the case of Examples, and as the best results in the case of Comparative Examples.

[0105] Straightness Evaluation

[0106] The straightness of the printed pattern was quantified by analyzing an image measured with an optical microscope. First, the image is binary-imaged by setting the printed pattern area to Black, and setting other areas (background areas) to White, and a horizontal line with Black:White of 1:1 is designated as a center line. Subsequently, the distance to the printed area (black) farthest to the outside of the printed area based on the center line was taken as (+), the distance to the unprinted area (white) farthest from the inside of the printed area based on the center line was taken as (−), and then the average values of (+) and (−) of two outside and inside parts of the edge area in the printed area were recorded as straightness.

[0107] The straightness was evaluated for the four printed lines (printed line from I to II, printed line from II to III, printed line from III to IV, and printed line from IV to I in FIG. 1), respectively, and described as the worst results among the results for the four printed lines in the case of Examples, and as the best results in the case of Comparative Examples.

[0108] Evaluation of Optical Density

[0109] The optical density was evaluated using a known optical density meter (341C manufactured by X-rite).

[0110] Folding Characteristics

[0111] Folding characteristics were evaluated by confirming the occurrence of cracks with the naked eye and optical microscope after folding the polymer film, on which the bezel printed pattern was printed as in FIG. 5, 200,000 times so that the area indicated by F in FIG. 5 was folded. The folding was performed to be folded at a rate of 1 Hz (once per second) with a curvature of 2.5R.

Example 1

[0112] A screen-printing ink was prepared by mixing FR260C-1 (manufactured by Asahi Chemical) as an ink comprising a polyester resin binder, and F-571 (manufactured by DIC) as a fluorine-based surfactant.

[0113] The FR260C-1 ink is an ink comprising 25 to 35 weight % of a polyester binder, comprising 50 to 60 weight % of diethylene glycol monoethyl ether acetate, comprising 10 to 20 weight % of carbon powder (CAS No. 1333-86-4), 2 weight % or less of an anti-foaming agent, and comprising 2 weight % or less of other additives, and the F-571 is a fluorine-based nonionic surfactant.

[0114] The ink was prepared by mixing the FR260C-1 (manufactured by Asahi Chemical) ink and the fluorine-based surfactant (F-571 (manufactured by DIC)) in a weight ratio of 100:0.5 (FR260C-1:F-571). Since the FR260C-1 comprises 25 to 35 weight % of the polyester binder, the weight ratio of the surfactant to 100 parts by weight of the binder is about 1.43 to 2 parts by weight or so.

[0115] The bezel was printed on a f-PET film (New polyester film, manufactured by MCC (Mitsubishi Chemical), thickness: 50 μm) as a polymer film through screen-printing using the prepared ink. The bezel printed pattern was printed as shown in FIG. 1.

[0116] As the screen-printing plate, a screen-printing plate of Poly catex 460 mesh was used. A pattern was formed on the screen-printing plate so that the bezel pattern as shown in FIG. 1 could be transferred to the polymer film as the film to be printed, where the printing width of the bezel (W in FIG. 1) was about 2 mm or so. The printing plate was placed on the polymer film to be printed, the prepared ink was applied on the printing plate, and then the ink was transferred on the polymer film by applying a pressure thereto. In this process, the squeegee angle was adjusted to about 80 degrees, the interval between the printing plate touched by the squeegee and the polymer film as a base material was about 3 mm or so, and the printing speed was controlled to about 40 mm/sec. After the above printing, the printed pattern was maintained at 100° C. for about 14 minutes and dried (single color printing). Thereafter, the same additional printing was performed on the dried printed pattern, and it was again maintained at 100° C. for about 14 minutes (two-color printing). After the two-color printing, the printing thickness was set to about 3.7 μm or so. Thereafter, a cover window (thickness: about 70 μm) was laminated using a known OCA (optical clear adhesive) with a thickness of 25 μm or so to manufacture a laminate comprising the cover window (100), the OCA (200), the bezel printed pattern (300) and the polymer film (400), as shown in FIG. 2.

Example 2

[0117] Upon preparing a screen-printing ink, the ink was prepared by setting the weight ratio of the FR260C-1 (manufactured by Asahi chemical) ink and the fluorine-based surfactant (F-571) to 100:0.1 (FR260C-1:F-571). Since the FR260C-1 comprises 25 to 35 weight % of the polyester binder, the weight ratio of the surfactant to 100 parts by weight of the binder is about 0.29 to 0.4 parts by weight or so.

[0118] Thereafter, the screen-printing was performed in the same manner as in Example 1, and the structure as shown in FIG. 2 was prepared, but at this time, the printing speed was adjusted to about 100 mm/sec or so, and the printing thickness was set in a level of about 4.7 μm.

Comparative Example 1

[0119] The screen-printing was performed in the same manner as in Example 1 using only FR260C-1 (manufactured by Asahi chemical) ink without mixing the fluorine-based surfactant, and the structure as in FIG. 2 was prepared.

Comparative Example 2

[0120] The screen-printing was performed in the same manner as in Example 1 except for using the ink prepared by mixing the FR260C-1 (manufactured by Asahi Chemical) ink and the fluorine-based surfactant (F-571) in a weight ratio of 100:0.01 (FR260C-1:F-571), and the structure of FIG. 2 was prepared. Since the FR260C-1 comprises 25 to 35 weight % of the polyester binder, the weight ratio of the surfactant to 100 parts by weight of the binder is about 0.029 to 0.04 parts by weight or so.

Comparative Example 3

[0121] The screen-printing was performed in the same manner as in Example 1 except for using the ink prepared by mixing the FR260C-1 (manufactured by Asahi Chemical) ink and the fluorine-based surfactant (F-571) in a weight ratio of 100:0.05 (FR260C-1:F-571), and the structure of FIG. 2 was prepared. Since the FR260C-1 comprises 25 to 35 weight % of the polyester binder, the weight ratio of the surfactant to 100 parts by weight of the binder is about 0.14 to 0.2 parts by weight or so.

Comparative Example 4

[0122] The screen-printing was performed in the same manner as in Example 1 except for using the ink prepared by mixing the FR260C-1 (manufactured by Asahi Chemical) ink and the fluorine-based surfactant (F-571) in a weight ratio of 100:1 (FR260C-1:F-571), and the structure of FIG. 2 was prepared. Since the FR260C-1 comprises 25 to 35 weight % of the polyester binder, the weight ratio of the surfactant to 100 parts by weight of the binder is about 2.9 to 4 parts by weight or so.

Comparative Example 5

[0123] The screen-printing was performed in the same manner as in Example 2 using only the FR260C-1 (manufactured by Asahi chemical) ink without mixing the fluorine-based surfactant, and the structure as in FIG. 2 was prepared.

Comparative Example 6

[0124] The screen-printing was performed in the same manner as in Example 2 except for using the ink prepared by mixing the FR260C-1 (manufactured by Asahi Chemical) ink and the fluorine-based surfactant (F-571) in a weight ratio of 100:0.01 (FR260C-1:F-571), and the structure of FIG. 2 was prepared. Since the FR260C-1 comprises 25 to 35 weight % of the polyester binder, the weight ratio of the surfactant to 100 parts by weight of the binder is about 0.029 to 0.04 parts by weight or so.

Comparative Example 7

[0125] The screen-printing was performed in the same manner as in Example 2 except for using the ink prepared by mixing the FR260C-1 (manufactured by Asahi Chemical) ink and the fluorine-based surfactant (F-571) in a weight ratio of 100:0.05 (FR260C-1:F-571), and the structure of FIG. 2 was prepared. Since the FR260C-1 comprises 25 to 35 weight % of the polyester binder, the weight ratio of the surfactant to 100 parts by weight of the binder is about 0.14 to 0.2 parts by weight or so.

Comparative Example 8

[0126] The screen-printing was performed in the same manner as in Example 2 except for using the ink prepared by mixing the FR260C-1 (manufactured by Asahi Chemical) ink and the fluorine-based surfactant (F-571) in a weight ratio of 100:1 (FR260C-1:F-571), and the structure of FIG. 2 was prepared. Since the FR260C-1 comprises 25 to 35 weight % of the polyester binder, the weight ratio of the surfactant to 100 parts by weight of the binder is about 2.9 to 4 parts by weight or so.

[0127] The results of Examples and Comparative Examples were summarized and described in Tables 1, 2 and 3 below.

TABLE-US-00001 TABLE 1 Examples 1 2 Printing thickness (μm) 3.72 ± 0.16 4.67 ± 0.16 Thickness uniformity (μm) 0.43 0.45 Edge top deviation (μm) 0.38 0.51 Optical density 5.93 6.06 Straightness (μm) 25.3 28.7 Thickness uniformity: difference between the maximum thickness and the minimum thickness in the printed pattern

TABLE-US-00002 TABLE 2 Comparative Examples 1 2 3 4 Printing thickness (μm) 3.89 ± 3.78 ± 3.82 ± 3.82 ± 0.19 0.16 0.21 0.19 Thickness uniformity(μm) 0.59 0.63 0.58 0.64 Edge top deviation (μm) 0.75 0.61 0.62 0.56 Optical density 5.95 5.94 5.94 5.63 Straightness (μm) 66.4 52.3 32.3 27.7 Thickness uniformity: difference between the maximum thickness and the minimum thickness in the printed pattern

TABLE-US-00003 TABLE 3 Comparative Examples 5 6 7 8 Printing thickness(μm) 4.64 ± 4.62 ± 4.60 ± 4.55 ± 0.26 0.21 0.16 0.28 Thickness uniformity(μm) 0.57 0.54 0.54 0.66 Edge top deviation (μm) 0.69 0.72 0.68 0.74 Optical density 6.18 6.19 6.21 5.93 Straightness (μm) 97.1 94.5 39.7 30.5 Thickness uniformity: difference between the maximum thickness and the minimum thickness in the printed pattern

[0128] As summarized in Tables 1 to 3, in the case of Examples, the bezel pattern was stably printed to have no edge top defect and excellent straightness while having thickness uniformity, but in the case of Comparative Examples, all of thickness uniformity, edge top characteristics, and straightness were not secured, or at least one of them was poor.

Test Example 1. Evaluation of Folding Durability

[0129] A polymer film having a bezel printed pattern as screen-printed according to Example 1 was applied to the folding test. FIG. 6 is an optical micrograph image of the printed pattern after the folding test, and it can be confirmed therefrom that the printed pattern is stably maintained without damage even after folding. In FIG. 6, the reference numeral 3000 is a printed area in which a printed pattern exists, and the reference numeral 4000 is an unprinted area in which a printed pattern does not exist.