WO2009133974A1

WO2009133974A1 - Method for manufacturing luminescent powder coating

Info

Publication number: WO2009133974A1
Application number: PCT/KR2008/002412
Authority: WO
Inventors: Eun Pyo Hong
Original assignee: Inhatech Co., Ltd.
Priority date: 2008-04-29
Filing date: 2008-04-29
Publication date: 2009-11-05

Abstract

Provided is a method for manufacturing a luminescent powder coating. A resin, a luminophor, a pigment, and additives are mixed. The mixture is molten and extruded. The extruded mixture is pulverized to a powder. Then, a portion of the powder out of a predetermined particle size range is removed through a classification. As such, the powder coating can form a luminescent coating film of a high quality, a high luminance, and a uniform color.

Description

METHOD FOR MANUFACTURING LUMINESCENT POWDER

COATING

Technical Field

[i]

[2] FIELD OF THE INVENTION

[3] The present inwntion relates to a method for manufacturing a luminescent powder coating, and more particularly, to a method for manufacturing a luminescent powder coating that can form a thick luminescent coating film.

[4]

[5] BACKGROUND OF THE INVENTION

[6] Various structures are provided with a characteristic of luminescence so that they can be easily seen at night.

[7] For example, a guardrail and a sound proof wall on a road, and an external wall of a building need a luminescent characteristic so that they can be easily saen at night to present unexpected accidents. To this end, the guardrail, the sound proof wall, and the external wall are applied with a luminescent coating to haw the luminescent characteristic. The conventional luminescent coatings are provided in liquid phases.

[8] To obtain a sufficient luminance, the luminescent coating needs to be coated thick.

However, the luminescent liquid coating is difficult to form a thick coating film because of its fluidity. Therefore, coating surface formed by the conventional luminescent liquid coating is too thin to have a sufficient luminance.

[9] There is no doubt that a thick coating film can be obtained by repeating the coating and drying operations several times. However, the repetition of these time-consuming operations may decrease the productivity and increase the process cost.

[10] A powder coating can form a thick coating film more easily than the liquid coating.

Therefore, a luminescent powder coating has been developed by mixing the powder coating with a luminophor. However, the conventional luminescent powder coating has low luminance.

[11] In consideration of the coatabiity of the powder coating, the size of powder particle is generally limited below 80 /M and if the powder particle is larger than 80 /M, the powder particle would not easily coated, therefore the average size of powder particle is preferably ranged from 35 to 50 /M, and it is preferable that the distribution of particle sizes is not wide. [13] SUMMARY OF THE INVENTION

[14] The present mention provides a method for manufacturing a luminescent powder coating that can form a coating film of a high quality, a high luminance, and a uniform color. This can be realized by presenting pulsation of a luminophor during the manufacturing of the powder coating, and by removing powder coating particles containing no luminophors through a classification.

[15]

[ 16] BRIEF DESCRIPTION OF THE DRAWINGS

[17] Exemplary embodiments can be understood in more detail from the following description taken in conjunction with the accompanying drawings, in which:

[18] Fig, 1 is a graph illustrating a particle size distribution of a typical powder coating,

[19] Fig, 2 is a graph illustrating a particle size distribution of a powder coating manufactured by a method in accordance with an exemplary embodiment of the present invention, and

[20]

[21 ] DETAILED DESCRIPTION OF THE INVENTION

[22] Hereinafter, specific embodiments will be described in detail with reference to the accompanying drawings. The present in^ention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present mention to those skilled in the art.

[23] A method for manufacturing a luminescent powder coating in accordance with an embodiment of the present invention is performed as follows. To begin with, raw materials including a resin, a luminophor, a pigment, and other addithes are mixed. The resin may be an epoxy resin, a polyester resin, or a combination thereof.

[24] Generally, fluorophors have extremely short afterglow time. However, certain fluorophors ha^e long afterglow time ranging from minutes to hours. Such a fluorophor is referred to as a long afterglow fluorophor or a phosphor. In the embodiments of the present k^ntion, the luminophor is preferably the luminescent fluorophor or the phosphor. The luminophor may be a typical material for storing light to emit light automatically at night. Preferably, the luminophor is an alkaline aluminate based phosphor. The alkaline aluminate based phosphor has the advantages of being harmless, higher luminance than a ZnS based phosphor, high cold resistance, and high heat resistance.

[25] It is preferable to use a luminophor of a large particle size because the luminophor has higher luminance as the particle size thereof increases. However, the size of the luminophor particle is limited as the size of the power coating particle of the invention is limited as shown below.

[26] The pigment is used for coloring the powder coating, and a typical pigment for a powder coating may be used as the pigment. The additives may be a hardener, a hardening accelerator, an antifoaming agent, a flowabiity control agent, or the like.

[27] After mixing the raw materials, the mixed raw materials are placed in an extruder, heated while being stirred, and then extruded. The extruded materials are pulverized into a powder. Since the sizes of the pulverized powder coating particles are not uniform yet, a classification is performed to separate the powder coating particles of a desired particle size.

[28] Generally, in view of coatabiity, the particle size of the powder coating is generally limited to approximately 80 μm or smaller. Thus, in the embodiment, the particle size of the powder coating is limited to approximately 80 μm or smaller. That is, the powder coating particles larger than approximately 80 μm are removed through the classification. In addition, as the particle size of the luminophor should be smaller than the size of the powder coating particle so that the luminophor can be contained in the powder coating, the powder coating particles smaller than the luminophor are also removed through the classification. This is because the powder coating particles smaller than the luminophor are assumed to contain no luminophors. Therefore, the removal of the powder coating particles smaller than the luminophor results in an increase of the concentration of the luminophor in the manufactured powder coating and it results in an increased luminance.

[29]

[30] EXAMPLE 1

[31] Luminances of the luminophors were measured according to the particle sizes of the luminophors. The luminophors were classified into four groups depending on thar particle sizes. Each group was irradiated by a tungsten lamp of 700 Lx for 20 minutes. 5 minutes after the irradiation, the luminance of each group was measured. The results are summarized in Table 1.

[32] Table 1

[34] [35] EXAMPLE 2 [36] Using the luminophors listed in Table 1, powder coatings wae manufactuied. Compositions of the powder coatings aie listed in Table 2. Coating films wae formed using the manufactuied powder coatings and then luminances theieof wee measuied. Light irradiation conditions wae the same as described in EXAMPLE 1. The measuied luminances of the coating films aie summarized in Table 3.

[37] Table 2 [38]

[39]

[40] Table 3

[42] [43] As shown in Table 1, the luminance of the luminophor was incieased as the particle size theieof is incieased. Howe\er, as shown in Table 3, the powder coating of experiment 4 containing the largest luminophor particles had a luminance lower than those of the powder coatings of the experiments 2 and 3 containing luminophor particles of the smaller particle sizes of 10 ~ 20 μm, and 30 ~ 50 μm, respectively. This is probably because the coating particles larger than 80 μm were remold through the classification, and thus the luminophor particles larger than 80 μm were also remold in the powder coating of the experiment 4. Howe\er, because a portion of the luminophor particles were pul\erized into small particles and got mixed in the powder coating during the manufacturing process of the powder coating, the powder coating of the experiment 4 still showed a luminance to some degree.

[44] In addition, as mentioned abore, the particle size of the powder coating is preferably below 80/M, and more preferably 35 to 50/M, SO the embodiment is also used the powder coating of this size range. Accordingly, the size of the luminophor should be smaller than the size of the power coating particle. Therefore, though Experiment 3 of the luminophor particle range 30 to 50/im shows best luminance, preferably, the smaller size luminophor is to be used. And the luminophor of Experiment 2 has smaller size than that of Experiment 3, and the luminance is relatively excellent. Therefore, it is preferable to use the luminophor size range 10 to 20 μm as shown in Experiment 2 of Example 2.

[45] [46] EXAMPLE 3 [47] In this example, the powder coating particles smaller than the used luminophors were removed through a classification. Thereafter, using the powder coatings, coating films were formed and irradiated, and then their luminances were measured. Experiments and measurements were performed under the same conditions as described in Example 2. The luminances of the coating films are summarized in Table 4. In the experiments 1 and 2, the powder coating particles smaller than 10 μm were remold. In the ex- periment 3, the powder coating particles smaller than 30 μm were remold. [48] Table 4

[49]

[50] [51] Comparing Tables 3 and 4, the removal of the powder coating particles smaller than the ruminophor particles improved the luminance of the coating film. This is because the concentration of the ruminophor in the powder coating was increased by the removal of the powder coating particles containing no luminophors.

[52] [53] EXAMPLE 4 [54] A particle size distribution of the typical powder coating and that of the powder coating of the experiment 2 of Example 3 were measured, respecthely. The measured particle size distributions are shown in Figs. 1 and 2.

[55] Referring to Figs. 1 and 2, the powder coating manufactured in the experiment 2 of Example 3 had a narrower particle size distribution range and more uniform particle sizes than the typical powder coating had. As mentioned above, if the particle size is excesshely large or small, the coatabiity of the powder coating is low, and the distribution of particle size of the embodiment is not wide, thus it is assumed that the powder coating manufactured in the experiment 2 of Example 3 has a superior coatabiity.

[56] [57] EXAMPLE 5 [58] Physical properties of the luminescent powder coating of the experiment 2 of Example 3 were tested. The test results are summarized in Table 5.

[59] Table 5

[61]

[62] [63] As described abore, the embodiments of the present indention provide the method for manufacturing a luminescent powder coating that contains a phosphor for a high luminance and can form a coating film of a high quality and a uniform color. According to the embodiments, powder coatings smaller than the luminophors are removed through the classification because they are expected to contain no luminophors. As such, the powder coating manufactured by the method can contain increased concentration of luminophors. In addition, the powder coating particles can hare similar electrification properties because their sizes do not range widely, and thus the powder coating can form a luminescent coating film of a uniform color and a high luminance.

[64] Although the method for manufacturing luminescent powder coating has been described with reference to the specific embodiments, it is not limited thereto. Therefore, it will be readily understood by those skilled in the art that various modifications and changes can be made thereto without departing from the spirit and scope of the present inrention defined by the appended claims.

Claims

[1] A method for manufacturing a luminescent powder coating, the method comprising: mixing a resin, a luminophor, a pigment, and an additive; extruding the mixture while bong molten; pulverizing the extruded mixture to a powder; removing a portion of the powder having a particle size smaller than a minimum particle size of the luminophor. [2] The method of claim 1, wherein the particle size of the luminophor ranges from

10 /M to 20 /M.