WO2007004764A1

WO2007004764A1 - Coating method of synthetic resin using urushi lacquer mixture

Info

Publication number: WO2007004764A1
Application number: PCT/KR2005/002351
Authority: WO
Inventors: Hyung-Chul Kim
Original assignee: Han-Kook National Corp.
Priority date: 2005-06-30
Filing date: 2005-07-20
Publication date: 2007-01-11

Abstract

Disclosed is a method of coating a synthetic resin with a urashi lacquer mixture. Specifically, this invention provides a method of coating a synthetic resin with a urushi lacquer mixture, including pretreating the surface of a synthetic resin, printing the synthetic resin, drying the printed synthetic resin, coating the synthetic resin with a mixture of filtered urushi lacquer and lacquer, and drying the coated synthetic resin. According to this invention, the synthetic resin coating method adopts a printing process, and thus the urushi lacquered synthetic resin may be easily produced on an industrial scale. Further, the synthetic resin may be coated with a mixture of ink and urushi lacquer so as to have various colors and patterns. Furthermore, since the urushi lacquer component applied on the synthetic resin of the present invention is excellent with respect to the absorption of harmful electromagnetic waves, far infrared emissivity, antibacterial activity and durability, such a resin can be variously applied to mobile phones, notebook computers, automobile interior materials, construction materials, etc.

Description

COATING METHOD OF SYNTHETIC RESIN USING URUSHI

LACQUER MIXTURE

Technical Field

[1] The present invention relates to a method of coating a synthetic resin with a urashi lacquer mixture, and more particularly, to a method of coating a synthetic resin with a urushi lacquer mixture, comprising pretreating the surface of a synthetic resin, printing the pretreated synthetic resin with a urushi lacquer mixture, drying the printed synthetic resin, coating the dried synthetic resin with a mixture of filtered urushi lacquer and lacquer, and drying the coated synthetic resin. Background Art

[2] In general, raw urushi lacquer or urushi lacquer collected from the lacquer tree is known to be composed mainly of urushiol, with small amounts of rubber, nitrogen- containing material, and water. Urushi lacquer, which is a kind of natural resin, has been used in a large amount in a manner such that it is mainly applied on wood to produce articles for living, such as wardrobes, vessels, spoons, chopsticks, and tables, in Korea, China and Japan for thousands of years. Further, it is also known that urushi lacquer has advantages such as high flame resistance, heat resistance, rot resistance, insect resistance, and electric insulation properties, and as well, the preservative quality thereof is good.

[3] Recently, various attempts to apply urushi lacquer to a synthetic polymer (Korean

Patent Laid-open Publication No. 2000-0024493) and to a ceramic and metal container (Korean Patent Laid-open Publication No. 2002-0072903), in addition to the wood products, have been made.

[4] However, the use of the urushi lacquer which is applied while keeping variously printed patterns clear has not yet been disclosed. Moreover, since the uncured urushi lacquer coating causes an allergic reaction in the human body, general users are reluctant to employ such lacquer. For these reasons, urushi lacquer has numerous difficulties in use. In addition, the urushi lacquer coating begins to cure from its surface most contacted with moisture and oxygen, and has very low oxygen permeability and moisture permeability. Thus, in order to cure the inner portion of the coating, there is the need for a UV drying process or a process of repeatedly applying and curing of urushi lacquer through a manual process, which is complicated. Thereby, while the production cost increases, economic benefits are negated, and consequently, it is difficult to realize industrial production of lacquer products. Disclosure of Invention Technical Problem

[5] Accordingly, the present invention has been made keeping in mind the above problems occurring in the related art, and an object of the present invention is to provide a method of coating a synthetic resin with a urushi lacquer mixture, which adopts a printing process such that a synthetic resin, having various colors, a urushi lacquer coating, excellent far infrared emission and electromagnetic wave-blocking effects, and superior antibacterial activity, can be produced on an industrial scale.

[6] Another object of the present invention is to provide a method of coating a synthetic resin with a mixture of urushi lacquer and lacquer, which adopts a printing process such that a synthetic resin, having various glosses and colors and high hardness, can be produced on an industrial scale.

Technical Solution

[7] In order to achieve the above objects, the present invention provides a method of coating a synthetic resin with a urushi lacquer mixture, comprising pretreating the surface of a synthetic resin, printing the synthetic resin through offset printing or silk screen printing using ink, drying the printed synthetic resin, coating the synthetic resin with a mixture of filtered urushi lacquer and varnish, and drying the coated synthetic resin.

[8] In addition, the present invention provides a method of coating a synthetic resin with a urushi lacquer mixture, comprising pretreating the surface of a synthetic resin, printing the synthetic resin through silk screen printing using a mixture of ink and urushi lacquer, drying the printed synthetic resin, coating the synthetic resin with a mixture of filtered urushi lacquer and varnish, and drying the coated synthetic resin.

[9] As such, the method of the present invention may further comprise coating the coated and dried synthetic resin using lacquer containing PMMA (polymethyl methacrylate) and MMA (methyl methacrylate) and then drying it.

[10] Hereinafter, a detailed description will be given of the present invention.

[11] Examples of the synthetic resin used in the present invention include polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), fluorine resin, acryl resin, poly acetic acid vinyl resin, polyamide resin, acetal resin, polycarbonate (PC), polyphenylene oxide, polyester, polysulfone, and polyimide. In particular, polyethylene terephthalate is preferable. The synthetic resin is surface polished and water washed to have a thickness of 0.01 ~ 7 D. Typically, since the synthetic resin has much dust attached thereto due to static electricity, a printing process must be conducted while removing such dust. In order to solve the problem, there are proposed methods of subjecting new equipment to antistatic treatment and of using an antistatic agent. [12] The pretreatment process may include a physical process, a chemical process or a primer process. Examples of the physical process include sand blasting, shot blasting, dry-ice blasting, hairline, and vibration, and examples of the chemical process include electrocoloring, and alkali degreasing for final washing in all tests.

[13] The primer treatment is used in the case where inorganic material such as plastic is difficult to adhere to the synthetic resin, and is also used for silk screen printing for a heater or various decorations and marks. Such a pretreatment process functions to increase adhesion upon printing and corrosion resistance. In the present invention, the primer treatment is preferably performed after washing and degreasing in order to increase adhesion.

[14] The pretreated synthetic resin is printed through offset printing or silk screen printing using ink capable of representing various colors and designs. As such, it is possible to print the synthetic resin through silk screen printing using a mixture comprising 5-95 wt% of ink capable of representing various colors and designs and 95-5 wt% of filtered urushi lacquer, in order to show various colors and enhance effects of urushi lacquer. In such a case, the type of ink for silk screen printing is not particularly limited, and preferably, pigment powder for use in raw material of ink is used.

[15] Shortly after the printing process, a drying process is conducted at 60~160°C for

30-90 min.

[16] The synthetic resin thus printed and dried is coated with urushi lacquer in a manner such that a mixture of urushi lacquer and varnish is prepared and then applied on the synthetic resin.

[17] As such, in the present invention, urushi lacquer native to Korea, China, Japan or

Southeast Asia may be used without limitation. Further, although such lacquer may have a composition varying with the production area, it may be independently applied. In the present invention, the urushi lacquer is used after a filtration process using filter paper to remove impurities therefrom. Thus, 95-98 wt% of the urushi lacquer thus filtered is mixed with 2-5 wt% of varnish, thus preparing the mixture. The mixture of urushi lacquer and varnish thus prepared is preferably applied though silk screen printing, but the present invention is not limited to such a printing process. Shortly after the application of the mixture of urushi lacquer and varnish, a drying process is conducted at 60~160°C for 30-90 min.

[18] In order to enhance gloss and weather resistance, the method of the present invention preferably further comprises coating the urushi lacquered synthetic resin thus dried using lacquer containing PMMA (polymethyl methacrylate) and MMA (methyl methacrylate) and then drying it.

[19] In such a case, the PMMA is acryl resin including MMA as a main monomer, and the admixture containing PMMA and MMA is used in an amount of 95-99 wt% based on the total weight of the lacquer, in which the PMMA and MMA are preferably admixed at 5~8:5~2. In particular, a ratio of PMMA and MMA of 6:4 is most preferable, in the interest of high transparency and desirable properties.

[20] The lacquer admixture is preferably applied through silk screen printing, but the present invention is not limited to such a printing process. Shortly after the application of the lacquer admixture, a drying process is conducted at 60- 16O⁰C for 30-90 min. In the present invention, the process of drying the printed synthetic resin is performed on a flat metal sheet at a temperature that is optimal to prevent cracking or peeling of the urushi lacquer coating upon curing and also to increase adhesion thereof.

[21] As shown in FIG. 2, the synthetic resin produced by the above method comprises a synthetic resin layer 10, a primer applied layer 20, a design printed layer 30, a urushi lacquered layer 40, and a lacquered layer 50, which are sequentially formed upwards.

[22] In addition, the present invention provides a method of coating a synthetic resin with a mixture of urushi lacquer and lacquer, comprising pretreating the surface of a synthetic resin, printing the synthetic resin through offset printing or silk screen printing, drying the printed synthetic resin, coating the synthetic resin with a mixture comprising filtered urushi lacquer and lacquer, and drying the coated synthetic resin.

[23] Further, with the goal of enabling the representation of various colors, the present invention provides a method of coating a synthetic resin with a mixture of ink and urushi lacquer using a silk screen printing process, comprising pretreating the surface of a synthetic resin, printing the synthetic resin through silk screen printing using a mixture of ink and urushi lacquer, drying the printed synthetic resin, coating the synthetic resin with a mixture of filtered urushi lacquer and lacquer, and drying the coated synthetic resin.

[24] In this case, pretreating the surface of the synthetic resin, printing the synthetic resin and drying the synthetic resin are conducted through the same processes as above.

[25] The printed and dried synthetic resin is coated with a mixture of urushi lacquer and a lacquer admixture. As such, the urushi lacquer, which is filtered using filter paper, is used in an amount of 5-90 wt% and the lacquer admixture is used in an amount of 95-10 wt% to prepare the mixture. When the amount of urushi lacquer is increased and the amount of lacquer is decreased, the surface gloss is decreased and the color is darkened. On the other hand, when the amount of urushi lacquer is decreased and the amount of lacquer is increased, the surface gloss is increased and the color becomes brightened. In this way, it is possible to perform the coating treatment in order to realize various glosses and colors according to the preferences of the consumer.

[26] In such a case, it is preferred that the Urushi lacquer be mixed with 5 wt% of varnish. The mixture of the Urushi lacquer and the lacquer admixture is preferably applied through silk screen printing, but the present invention is not limited to such a printing process.

[27] The lacquer admixture containing the PMMA and the MMA is used in an amount of 20-80 wt% based on the total weight of the mixture to be applied, in which the PMMA and MMA are preferably admixed at a ratio of 5~8:5~2. In particular, a ratio of PMMA to MMA of 6:4 is most preferable in the interest of high transparency and desirable properties.

[28] Shortly after the application of the mixture of the Urushi lacquer and the lacquer admixture, a drying process is conducted at 60- 16O⁰C for 30-90 min. In the present invention, the process of drying the printed synthetic resin is conducted on a flat metal sheet at a temperature that is optimal to prevent cracking or peeling of the Urushi lacquer coating upon curing and also to increase adhesion thereof.

[29] As shown in FIG. 7, the synthetic resin produced by the above method comprises a synthetic resin layer 10, a primer applied layer 20, a design printed layer 30, and a layer 40' of the mixture of Urushi lacquer and lacquer, which are sequentially formed upwards.

Advantageous Effects

[30] According to the present invention, since the synthetic resin coating method adopts a printing process, the urushi lacquered synthetic resin can be easily produced on an industrial scale. Further, the synthetic resin can be coated with a mixture of ink and urushi lacquer so as to have various colors and patterns. Furthermore, since the urushi lacquer component applied on the synthetic resin is superior with respect to the absorption of harmful electromagnetic waves, far infrared emissivity, antibacterial activities, and durability, such a synthetic resin can be variously applied to mobile phones, notebook computers, automobile interior materials, construction materials, etc. Brief Description of the Drawings

[31] FIG. 1 is a flowchart showing the process of coating a synthetic resin with a mixture of urushi lacquer and varnish, according to the present invention;

[32] FIG. 2 is a sectional view of the synthetic resin coated with the mixture of urushi lacquer and varnish, produced according to the process of the present invention;

[33] FIG. 3 is a photograph of a polyethylene terephthalate (PET) resin coated with the mixture of urushi lacquer and varnish, produced according to the process of the present invention;

[34] FIG. 4 is a flowchart showing the process of coating a synthetic resin with a mixture of ink and urushi lacquer through silk screen printing, according to a first embodiment of the present invention;

[35] FIG. 5 is photographs of the PET resin printed with the mixture of 50 wt% of ink and 50 wt% of urushi lacquer through silk screen printing and then coated with the mixture of urushi lacquer and varnish; [36] FIG. 6 is a flowchart showing the process of coating a synthetic resin with a mixture of urushi lacquer and lacquer, according to the present invention; [37] FIG. 7 is a sectional view of the synthetic resin coated with the mixture of urushi lacquer and lacquer, produced according to the process of the present invention; [38] FIG. 8 is photographs of a polycarbonate (PC) resin coated with the mixture of urushi lacquer and lacquer, produced according to the process of the present invention; [39] FIG. 9 is a flowchart showing the process of coating a synthetic resin with a mixture of ink and urushi lacquer through silk screen printing, according to a second embodiment of the present invention; and [40] FIG. 10 is photographs of the PET resin printed with the mixture of 50 wt% of ink and 50 wt% of urushi lacquer through silk screen printing and then coated with the mixture of urushi lacquer and lacquer.

Mode for the Invention [41] A better understanding of the present invention may be obtained through the following examples, test examples and tables which are set forth to illustrate, but are not to be construed as the limit of the present invention. [42] Example 1. Coating of Synthetic Resin using Urushi Lacquer

[43] 1-1. Coating of Ink-printed Synthetic Resin using Urushi Lacquer

[44] FIG. 1 illustrates the process of coating a synthetic resin, according to the present invention. Specifically, 0.25-0.30 kg of a PET resin (available from Saehan) having a thickness of 0.1 mm was surface polished, water washed and surface cleaned with a degreasing agent. Thereafter, the PET resin was coated thinly with 100-200 g/m of a primer (available from Cromtryck, Sweden) and allowed to stand for 20-30 min, thus completing a pretreatment process. [45] Subsequently, a predetermined design pattern was printed on the PET resin through offset printing using ink, after which the resin was dried in a box oven (available from

Taeyang Electronic Company) at 14O⁰C for 1 hour. [46] Raw Urushi lacquer native to China was filtered with filter paper and then mixed with 5 wt% of varnish based on the total weight of the filtered Urushi lacquer to prepare a Urushi lacquer mixture, which was then applied to a thickness of 1.5-2.5 D on the printed PET resin through silk screen printing. Thereafter, the resin was dried in a box oven at 14O⁰C for 1 hour. [47] 1-2. Coating of Synthetic Resin printed with Mixture of Ink and Urushi Lacquer

Using Urushi Lacquer [48] FIG. 4 illustrates the process of coating a synthetic resin with a mixture of ink and urashi lacquer through silk screen printing, according to a first embodiment of the present invention. Specifically, 0.25-0.30 kg of a PET resin (available from Saehan) having a thickness of 0.1 mm was surface polished, water washed and surface cleaned with a degreasing agent. Thereafter, the PET resin was coated thinly with 100-200 g/m of a primer (available from Cromtryck, Sweden), and allowed to stand for 20-30 min, thus completing a pretreatment process.

[49] Subsequently, the PET resin was printed with each of a mixture of 50 wt% of black ink for PET (available from M.D.S) and 50 wt% of urushi lacquer and a mixture of 50 wt% of blue ink for PET (available from M.D.S) and 50 wt% of urushi lacquer through silk screen printing, and then dried in a box oven (available from Taeyang Electronic Company) at 14O⁰C for 1 hour.

[50] Raw urushi lacquer native to China was filtered with 300 mesh filter paper and was then mixed with 5 wt% of varnish based on the total weight of the filtered urushi lacquer to prepare a Urushi lacquer mixture, which was then applied to a thickness of 1.5-2.5 D on the printed PET resin through silk screen printing. Subsequently, the resin was dried in a box oven at 14O⁰C for 1 hour.

[51] Example 2

[52] Coating of Urushi Lacquered Synthetic Resin using Lacquer

[53] On the urushi lacquered PET resin of Example 1, lacquer (plex6788, available from

ROHM), containing PMMA and MMA admixed at 6:4, was applied through silk screen printing. Thereafter, the resin was dried in a box oven at 100⁰C for 1 hour, thus producing lacquered PET resins (FIGS. 3 and 5).

[54] Example 3

[55] Coating of Synthetic Resin using Mixture of Urushi Lacquer and Lacquer

[56] 3- 1. Coating of Ink-Printed Synthetic Resin using Mixture of Urushi Lacquer and

Lacquer

[57] FIG. 6 illustrates the process of coating a synthetic resin, according to the present invention. Specifically, a PC resin (available from Eopzone) was surface polished, water washed and then surface cleaned with a degreasing agent, after which the PC resin was coated thinly with 100-200 g/m of a primer (available from Cromtryck, Sweden) and then allowed to stand for 20-30 min, thus completing a pretreatment process.

[58] Subsequently, a predetermined design pattern was printed on the PC resin through offset printing using ink, and then the resin was dried in a box oven (available from Taeyang Electronic Company) at 16O⁰C for 1 hour.

[59] Raw urushi lacquer was filtered with 300 mesh filter paper and then mixed with 5 wt% of varnish based on the total weight of the filtered Urushi lacquer. Thereafter, the urushi lacquer thus mixed was further mixed with a lacquer admixture containing PMMA and MMA (plex6788, available from ROHM) admixed at 6:4, according to varying weight ratios as shown in Table 1 below, thus preparing a mixture of Urushi lacquer and lacquer. Subsequently, the mixture thus obtained was applied to a thickness of 1.5-2.5 D on the printed PC resin through silk screen printing. Then, the resin was dried in a box oven at 16O⁰C for 1 hour, thereby yielding PC resins coated with the Urushi lacquer mixture (FIG. 7).

[60] Table 1

[61] As a result, as seen in FIG. 7, it has been confirmed that the color of the resin is darkened as the amount of urushi lacquer is increased (A: 10 wt% of urushi lacquer + 90 wt% of lacquer admixture and B: 30 wt% of urushi lacquer + 70 wt% of lacquer admixture).

[62] 3-2. Coating of Synthetic Resin printed with Mixture of Ink and Urushi Lacquer using Mixture of Urushi Lacquer and Lacquer [63] FIG. 9 illustrates the process of coating a synthetic resin with a mixture of ink and urushi lacquer through silk screen printing, according to a second embodiment of the present invention. Specifically, 0.25-0.30 kg of a PET resin (available from Saehan) having a thickness of 0.1 mm was surface polished, water washed and surface cleaned with a degreasing agent. Thereafter, the PET resin was coated thinly with 100-200 g/m of a primer (available from Cromtryck, Sweden), and allowed to stand for 20-30 min, thus completing a pretreatment process.

[64] The PET resin was printed with each of a mixture of 50 wt% of red ink for PET (available from M.D.S) and 50 wt% of urushi lacquer, a mixture of 50 wt% of silver ink for PET (available from M.D.S) and 50 wt% of urushi lacquer, a mixture of 50 wt% of white ink for PET (available from M.D.S) and 50 wt% of urushi lacquer, and a mixture of 50 wt% of yellow ink for PET (available from M.D.S) and 50 wt% of urushi lacquer through silk screen printing, after which the resin was dried in a box oven (available from Taeyang Electronic Company) at 14O⁰C for 1 hour.

[65] Raw urushi lacquer was filtered with 300 mesh filter paper and was then mixed with 5 wt% of varnish based on the total weight of the filtered Urushi lacquer. Thereafter, 10 wt% of the urushi lacquer thus obtained was further mixed with 90 wt% of the lacquer admixture containing PMMA and MMA (plex6788, available from ROHM) admixed at 6:4, after which the resulting mixture was applied to a thickness of 1.5-2.5 D on the printed PET resin through silk screen printing. Subsequently, the resin was dried in a box oven at 16O⁰C for 1 hour, thus producing PET resins coated with the urushi lacquer mixture (A, B, C and D of FIG. 10).

[66] Test Example 1. Test of Specific Absorption Rate [67] Mobile phone cases were manufactured by the present inventors using the PET resin of Example 2 through a thermofusion process typically used in attachment of synthetic resin. Such mobile phone cases and commercially available mobile phone cases of manufacturers A and B were measured with respect to their specific absorption rate for evaluating the absorption of electromagnetic waves under conditions given in Table 2 below by Hyundai Calibration & Certification Technologies Co. Ltd.

[68] Table 2

[69] Table 3

[70] As is apparent from Table 3, the four mobile phone cases exhibit a specific absorption rate of 1.6 W/kg or less, satisfying the standard for exposure to electromagnetic waves. In particular, of these mobile phone cases, the mobile phone cases manufactured using the PET resin produced by the method of the present invention can be seen to have superior specific absorption rate of 0.108 and 0.098.

[71] Test Example 2. Test of Far Infrared Emission [72] The emissivity of far infrared rays emitted from the PET resin of Example 2 was measured by Korea Institute of Far Infrared Applied Estimation at the present inventors' request.

[73] Specifically, the emissivity of the PET resin was determined at 37⁰C using an FT-IR spectrometer, compared to that of a black body. The results are given in Table 4 below. As is apparent from Table 4, it has been confirmed that high far infrared emissivity can be exhibited.

[74] Table 4

[75] Test Example 3. Test of Antibacterial Activity [76] The test for antibacterial activity of the PET resin of Example 2 was conducted by Korea Testing and Research Institute for Chemical Industry at the present inventors' request. In this case, the test strains were Escherichia CoIi (ATCC 8739) and Staphylococcus aureus (ATCC 6538).

[77] Table 5

[78] Note: A is the bacterial cell number (average) of the control sample shortly after inoculation, B is the bacterial cell number (average) after 24 hours of incubation, and C is the bacterial cell number (average) of the PET resin after 24 hours of incubation. In addition, an antibacterial value (log(B/C)) results from subtraction of log(C/A) from log(B/A).

[79] As is apparent from Table 5, it has been confirmed that the urushi lacquered synthetic resin of the present invention exhibits excellent antibacterial activity.

[80] Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. Industrial Applicability

[81] As described hereinbefore, the present invention provides a method of coating a synthetic resin with a urushi lacquer mixture. According to the present invention, the synthetic resin coating method adopts a printing process, and thus the urushi lacquered synthetic resin may be easily produced on an industrial scale, and also may have various colors and patterns thanks to the use of ink. Further, since the urushi lacquer component applied on the synthetic resin of the present invention is excellent with respect to the absorption of harmful electromagnetic waves, far infrared emissivity, antibacterial activity, and durability, such a synthetic resin can be variously applied to mobile phones, notebook computers, automobile interior materials, construction materials, etc.

Claims

[1] A method of coating a synthetic resin with a urushi lacquer mixture, comprising: pretreating a surface of a synthetic resin; printing the synthetic resin through offset printing or silk screen printing; drying the printed synthetic resin; coating the synthetic resin with a mixture of filtered urushi lacquer and varnish; and drying the coated synthetic resin. [2] A method of coating a synthetic resin with a urushi lacquer mixture, comprising: pretreating a surface of a synthetic resin; printing the synthetic resin through silk screen printing using a mixture of 5-95 wt% of ink and 95-5 wt% of urushi lacquer; drying the printed synthetic resin; coating the synthetic resin with a mixture of filtered urushi lacquer and varnish; and drying the coated synthetic resin. [3] The method according to claim 1 or 2, wherein the synthetic resin is at least one selected from the group consisting of polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), fluorine resin, acryl resin, poly acetic acid vinyl resin, polyamide resin, acetal resin, polycarbonate (PC), polyphenylene oxide, polyester, polysulfone, and polyimide. [4] The method according to claim 3, wherein the mixture of the urushi lacquer and the varnish comprises 95-98 wt% of urushi lacquer and 2-5 wt% of varnish, based on total weight of the mixture. [5] The method according to claim 1 or 2, further comprising coating the coated and dried synthetic resin using lacquer containing PMMA (polymethyl methacrylate) and MMA (methyl methacrylate) and then drying it. [6] The method according to claim 5, wherein the lacquer comprises the PMMA and the MMA admixed at 5-8:5-2. [7] A method of coating a synthetic resin with a urushi lacquer mixture, comprising: pretreating a surface of a synthetic resin; printing the synthetic resin through offset printing or silk screen printing; drying the printed synthetic resin; coating the synthetic resin with a mixture of filtered urushi lacquer and lacquer; and drying the coated synthetic resin. [8] A method of coating a synthetic resin with a urushi lacquer mixture, comprising: pretreating a surface of a synthetic resin; printing the synthetic resin through silk screen printing using a mixture of 5-95 wt% of ink and 95-5 wt% of urushi lacquer; drying the printed synthetic resin; coating the synthetic resin with a mixture of filtered urushi lacquer and lacquer; and drying the coated synthetic resin. [9] The method according to claim 7 or 8, wherein the synthetic resin is at least one selected from the group consisting of polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), fluorine resin, acryl resin, poly acetic acid vinyl resin, polyamide resin, acetal resin, polycarbonate (PC), polyphenylene oxide, polyester, polysulfone, and polyimide. [10] The method according to claim 9, wherein the mixture of the urushi lacquer and the lacquer comprises 5-90 wt% of urushi lacquer and 95-10 wt% of lacquer, based on total weight of the mixture. [11] The method according to claim 7 or 8, wherein the lacquer comprises the PMMA and the MMA admixed at 5-8:5-2.