Process for preparing coated ABS sheet

Abstract

A method of preparing an acrylonitrile butadiene styrene (ABS) sheet includes: a first step of hydrophilizing the surface of an ABS substrate by coating a surfactant solution on the substrate; a second step of washing the surfactant-coated ABS substrate with distilled water and drying the surfactant-coated ABS substrate; a third step of forming an intermediate film by coating poly(3,4-ethylenedioxythiophen)-polystyrene sulfonate (PEDOT-PSS) on top of the dried ABS substrate; and a fourth step of coating a fluorinated polymer solution of poly(vinylidene fluoride-trifluoroethylene) on top of the intermediate film.

Claims

1. A method of preparing an acrylonitrile butadiene styrene (ABS) sheet, the method comprising: a first step of hydrophilizing the surface of an ABS substrate by coating a surfactant solution on the substrate; a second step of washing the surfactant-coated ABS substrate with distilled water and drying the surfactant-coated ABS substrate; a third step of forming an intermediate film by coating poly(3,4-ethylenedioxythiophen)-polystyrene sulfonate (PEDOT-PSS) on top of the dried ABS substrate; and a fourth step of coating a fluorinated polymer solution of poly(vinylidene fluoride-trifluoroethylene) on top of the intermediate film.

2. The method of claim 1, wherein the surfactant solution is an aqueous sodium dodecyl sulfate solution.

3. The method of claim 1, wherein the drying is conducted at a temperature range of 40 to 60 C.

4. The method of claim 1, wherein a concentration of the fluorinated polymer solution is 1 to 8 wt %, and in the fourth step, the coating is conducted at a coating rate of 1500 to 4500 rpm.

5. The method of claim 1, wherein the concentration of the fluorinated polymer solution is 2 to 5 wt %, and in the fourth step, the coating is conducted at a coating rate of 3000 to 4500 rpm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above and other features of embodiments of the present invention will now be described in detail with reference to certain exemplary embodiments thereof illustrated the accompanying drawings which are given hereinbelow by way of illustration only, and thus are not limitative of the present invention, and wherein:

(2) FIG. 1 is an image comparing droplet spreading phenomenon before and after coating a surfactant on the ABS substrate surface;

(3) FIG. 2 is an graph comparing gloss of the ABS substrate surface depending on whether a washing process is conducted after surfactant coating or not;

(4) FIG. 3 is a graph comparing gloss change depending on a concentration of P(VDF-TrFE) solution;

(5) FIG. 4 is a graph comparing 60 (degree) gloss change of the ABS sheet prepared in Example 1 and the bare ABS substrate of Comparative Example 1;

(6) FIG. 5 is a graph comparing surface roughness change of the ABS sheet prepared in Example 1 and the bare ABS substrate of Comparative Example 1; and

(7) FIG. 6 is an image comparing a droplet contact angle of the ABS sheet prepared in Example 1 and the bare ABS substrate of Comparative Example 1.

(8) It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various preferred features illustrative of the basic principles of embodiments of the invention. The specific design features of embodiments the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particular intended application and use environment.

DETAILED DESCRIPTION

(9) Hereinafter reference will now be made in detail to various embodiments of the present invention, examples of which are illustrated in the accompanying drawings and described below. While exemplary embodiments of the invention are be described below, it will be understood that present description is not intended to limit the invention to those exemplary embodiments. On the contrary, the invention is intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined by the appended claims.

(10) Embodiments of the present invention include a high gloss ABS sheet having improved surface roughness and increased gloss, and a method for preparing thereof.

(11) In the high gloss ABS sheet according to an embodiment of the present invention, an intermediate film of poly(3,4-ethylenedioxythiophen)-polystyrene sulfonate (hereinafter, abbreviated as PEDOT-PSS) is formed on top of an ABS substrate, and a fluorinated resin film of poly(vinylidene fluoride-trifluoroethylene) (hereinafter, abbreviated as P(VDF-Tree)) is formed on top of the intermediate film.

(12) In embodiments of the present invention, instead of directly coating the fluorinated resin film on the ABS substrate, a hydrophilic polymer film of PEDOT-PSS is used as the intermediate film. Accordingly, compared to the ABS substrate, surface roughness and gloss are able to be improved.

(13) The method for preparing a high gloss ABS plastic sheet according to an embodiment of the present invention will be described step by step in detail as follows.

(14) The first step is a pretreatment process of semi-permanently changing the surface characteristic of the ABS substrate from hydrophobic to hydrophilic by coating a surfactant solution on top of the ABS substrate.

(15) As illustrated by the image of FIG. 1, a droplet contact angle of the ABS substrate became significantly low by coating the surfactant solution on the ABS substrate. Thus, it can be found that the ABS substrate surface is hydrophilized.

(16) Compared to a general hydrophilizing method, UV ozonization, the ABS substrate coated with the surfactant was able to maintain hydrophilicity more consistently.

(17) An example of a method for treating the ABS substrate with the surfactant solution will be described in detail as follows. The surfactant solution was coated on top of the ABS substrate. At this time, sodium dodecyl sulfate was used as a surfactant, and it was added to distilled water followed by mixing thereof for 30 min or longer to obtain the surfactant solution at a concentration of 0.5 to 3 wt %. In various embodiments of the present invention, coating may be performed by various methods. For example, the surfactant solution was coated using a spin coater while sequentially increasing a rate from 500 rpm to 3000 rpm. However, the coating is not limited to spin coating; other coating methods may be used.

(18) The second step is a process of washing the surfactant-coated ABS substrate with distilled water and drying thereof.

(19) In certain embodiments, this is a process of washing with distilled water to enhance the surface of the ABS substrate, which became rough due to the surfactant coating. The washing time may vary depending on water intensity. In certain embodiments, it may be conducted for about 20 sec to 1 min. The ABS substrate washed with distilled water is dried at a temperature range of 40 to 60 C. for about 10 to 60 min.

(20) In FIG. 2, the result of comparing gloss of the ABS substrate surface depending on whether the washing process is conducted after surfactant coating or not is shown. According to FIG. 2, it could be confirmed that surface roughness and gloss of the ABS substrate that is additionally subjected to the distilled water washing process is improved.

(21) The third step is a process of forming the intermediate film by coating the substrate with the PEDOT-PSS polymer solution.

(22) Namely, this is a process of coating the water soluble polymer of PEDOT:PSS on the surfactant-coated ABS substrate surface. The ABS substrate is semi-permanently hydrophilized through the pretreatment process of coating with the surfactant, and therefore, an effect of making the water soluble polymer of PEDOT:PSS possible to form a more homogeneous water soluble polymer film can be obtained.

(23) In an embodiment, the coating of the PEDOT-PSS was conducted by coating using a spin coater while increasing a rate from 500 rpm to 3000 rpm. However, other coating methods and rates may be used.

(24) The fourth step is a process of coating the fluorinated polymer solution.

(25) As the fluorinated polymer, P(VDF-TrFE) having weight average molecular weight of 10,000 or more, preferable of a range of 50,000 to 1,000,000 was used. The P(VDF-TrFE) was dissolved in a polar solvent, 2-butanone, before use, and preferably, it was completely dissolved by stirring at a temperature of 80 to 90 C. and a rate of 400 rpm for about 1 hour before use.

(26) In certain embodiments, a concentration of the fluorinated polymer solution may be in a range of 1 to 8 wt %. In certain embodiments, the concentration of the fluorinated polymer solution may be in a range of 2 to 7 wt %. In certain embodiments, a rate of coating the P(VDF-TrFE) solution on the ABS substrate may be maintained at 1500 to 4500 rpm. In certain embodiments, a rate of coating the P(VDF-TrFE) solution on the ABS substrate may be 3000 to 4500 rpm. As generally, there is a tendency that gloss is increased as a coating rate is increased, average gloss was sharply improved to 90% or more at a coating rate of 3000 rpm or more.

(27) FIG. 3 is a graph comparing gloss change depending on a concentration of P(VDF-TrFE) solution. Namely, when coating the P(VDF-TrFE) solution on the ABS substrate at a coating rate of 3500 rpm, the fluorinated polymer solution was prepared at a concentration of 1 wt %, 3 wt % and 7.5 wt %, respectively, coated, and then gloss was compared. According to FIG. 3, it could be confirmed that gloss was the best as 95% or more when a concentration of the P(VDF-TrFE) solution was 3 wt %.

EXAMPLES

(28) The following examples illustrate embodiments of the invention and are not intended to limit the scope of the invention.

Example 1

(29) 1) Surfactant Coating Process

(30) An 5 cm5 cm ABS substrate was prepared. Sodium dodecyl sulfate (Product of Sigma-Aldrich) was added to distilled water, and mixed for 30 min or longer to prepare a surfactant solution at a concentration of 3 wt %. A surfactant solution was coated on top of the ABS substrate using a spin coater while sequentially increasing a rate from 500 rpm.fwdarw.1000 rpm.fwdarw.3000 rpm.

(31) 2) Process of Washing with Distilled Water and Drying

(32) In order to enhance roughness of the surface caused by surfactant coating, the ABS substrate was washed under running distilled water for 30 sec. The ABS substrate washed with distilled water was dried using a hot plate at 50 C. for 10 min.

(33) 3) Process of Forming Water Soluble Polymer Intermediate Film

(34) PEDOT:PSS polymer (Product of Heraeus, German) was filtered through a 0.45 m syringe filter (Manufacturer: advantec), and then used as a coating solution. The PEDOT:PSS coating solution was coated on top of the ABS substrate using a spin coater while sequentially increased a rate from 500 rpm.fwdarw.1000 rpm.fwdarw.3000 rpm.

(35) 4) Process of Forming Fluorinated Resin Film

(36) As a fluorinated polymer, P(VDF-TrFE) having weight average molecular weight of 200,000 (Product of piezotech, France) was used. The P(VDF-TrFE) was dissolved in 2-butanone (Product of Sigma-aldrich, 99.7% pure) to prepare a solution at a concentration of 3 wt %. The P(VDF-TrFE) solution was coated on top of the ABS substrate using a spin coater at a coating rate of 3500 rpm.

(37) Gloss, surface roughness and contact angle of the ABS sheet prepared above were measured, and shown in the following Table 1.

Comparative Example 1

(38) A 5 cm5 cm ABS substrate was used as Comparative Example 1, and it was marked as bare ABS in the following Table 1. Gloss, surface roughness and contact angle of the bare ABS were measured, and shown in the following Table 1.

Comparative Examples 2 to 4

(39) In preparing the ABS sheet according to Comparative Examples 2-4, after coating the surfactant, the process of washing with distilled water was omitted. And, in Comparative Examples 2 to 4, when coating the 3 wt % fluorinated resin solution is coated on top of the ABS substrate coated with the water soluble polymer intermediate film, a coating rate was changed to 3000 rpm (Comparative Example 2), 3500 rpm (Comparative Example 3) and 5000 rpm (Comparative Example 4), respectively.

(40) Gloss, surface roughness and contact angle of the ABS sheets prepared in Comparative Examples 2 to 4 were measured, and shown in the following Table 1.

Comparative Examples 5 to 7

(41) In preparing the ABS sheet according to Comparative Examples 5 to 7, the fluorinated resin was coated while changing a concentration of the coating solution or a coating rate from that of Example 1.

(42) Namely, Comparative Example 5 is an example of preparing the ABS sheet by preparing a fluorinated resin solution of 3 wt %, and coating thereof while increasing a coating rate to four steps from 500 rpm.fwdarw.1000 rpm.fwdarw.2000 rpm.fwdarw.3500 rpm, thereby preparing an ABS sheet. Comparative Example 6 is an example of preparing a fluorinated resin solution of 1 wt %, and coating thereof while maintaining a coating rate to 3500 rpm, thereby preparing an ABS sheet. Comparative Example 7 is an example of preparing a fluorinated resin solution of 7.5 wt %, and coating thereof while maintaining a coating rate to 3500 rpm, thereby preparing an ABS sheet.

(43) Gloss, surface roughness and contact angle of the ABS sheets prepared in Comparative Examples 5 to 7 were measured, and shown in the following Table 1.

(44) TABLE-US-00001 TABLE 1 Example Comparative Example Section 1 1 2 3 4 5 6 7 Fluorinated Conc. 3 Bare 3 3 3 3 1 7.5 Resin (wt %) ABS Coating 3500 3000 3500 5000 3500 (4step) 3500 3500 Rate (rpm) Whether conducting Yes No No No Yes Yes Yes Washing Process or not Gloss 96 85.4 58.8 55 71.0 65.6 62.3 72.9 Roughness (nm) 12.5 31.0 10.8 15.8 19.7 Not Not Out Average Roughness (nm) 9.9 24.0 8.6 19.6 15.4 Not Not Out Contact Angle () 85.6 78.3 Not: not measured Out: Impossible to measure because it is over rms 300 nm

(45) Further, in FIGS. 4-6, the results of measuring 60 (degree) gloss change, surface roughness change, and droplet contact angle of the bare ABS substrate of Comparative Example 1 and the ABS sheet prepared in Example 1 were compared.

(46) FIG. 4 is the result of comparing gloss, it could be confirmed that gloss of the ABS sheet prepared in Example 1 was improved about average 13%, compared to the ABS substrate surface.

(47) An image of the 3030 surface area was obtained using an AFM, root mean square (rms), that is a surface roughness value, was calculated, and the illustrated in FIG. 5. It could be confirmed that surface roughness was improved average 59%.

(48) FIG. 6 is the result of comparing droplet contact angle, and it could be confirmed that surface hydrophobicity was improved.

(49) According to embodiments of the present invention, instead of conducting a process of coating a polyurethane coating composition, high gloss can be realized to an ABS plastic material by coating a fluorinated resin.

(50) The high gloss ABS sheet prepared in embodiments of the present invention is useful as a vehicle interior material.

(51) The invention has been described in detail with reference to preferred embodiments thereof. However, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.