KR20130093393A - A method for preparing resin coating composition containing nano diamond powder and a coating method using the composition - Google Patents

Abstract

PURPOSE: A manufacturing method of a resin coating agent, using diamond particle is provided to offer scratch resistance, weather resistance, UV resistance, and staining resistance by dispersed diamond particle. CONSTITUTION: A manufacturing method of a resin coating agent, using diamond particle comprises the steps of: dispersing nano diamond powder in a solvent by using bead milling; reacting the solution obtained by the previous step with a silane coupling agent having acrylate group, amine group, or mercapto propyl group as an organic functional group; and mixing the silane-added solution obtained by the previous step with monomer, oligomer compound, or silane precursor. The solvent above is C1-3 lower alcohol.

Description

A method for preparing resin coating composition containing nano diamond powder and a coating method using the composition}

The present invention relates to a method for preparing a resin coating agent using diamond particles and a coating method using the same. More specifically, the nanodiamond is reacted using a silane coupling agent and then mixed with a coating solution to prepare a coating agent. The method of manufacturing a resin coating agent and a coating using the same, which have excellent surface protection when applied to automobile exterior parts by improving the scratch resistance, weather resistance, and UV resistance while maintaining excellent transparency by coating the surface of the plastic It is about a method.

The use of plastic materials to increase the weight of automobile exterior parts is increasing, and the development of the direction of extending the life of components by applying a coating to protect the material on the metal surface as well as the plastic material is being actively progressed. In particular, glass materials in automobiles account for a large part of the exterior parts, and the proportion of the automobile parts in the weight of automobiles is about 3.5. Therefore, research is being actively conducted to replace the glass of automobiles with plastic of specific material (specific gravity 1.2) to achieve light weight, and there are some commercially available technologies. However, as a limitation of the transparent plastic material, wear resistance (scratch resistance) is weak, there is a problem such as discoloration caused by sunlight, there are many restrictions on use.

In order to solve this problem, coatings have been researched and applied to improve the wear resistance (scratch resistance) by applying various coatings on the transparent plastic surface and to minimize the change of physical properties even in sunlight and various external environmental changes. Representatively, a technique of forming a coating film by using a plasma deposition method on a polycarbonate (PC) material or coating a SiO ₂ based paint by a coating wet method has been applied.

Conventionally, friction characteristics were improved by using a solution in which a dispersion solution of silane-treated nanodiamond powders, such as a commercial polytetrafluoroethylene (PTFE) coating solution, was used as a coating agent. As an example, Korean Patent Application Publication No. 2010-0103242 No. 2, wherein the nanodiamond powder is dispersed in a polar organic solvent, a first step and a second step of mixing the dispersion solution obtained in the first step with a silane coupling agent, wherein the silane coupling agent is an organic functional group, at least from a mercapto group or an amino group. Having either; And a third step of mixing the silane treatment solution obtained in the second step with an oil-based PTFE coating solution, and a method of coating and coating a PTFE coating agent and heat-treating the PTFE coating agent after natural or hot air drying. Is proposed. However, the PTFE-based composite resin used in the present invention cannot be used in a transparent resin due to lack of transparency, and the hardness of the base material itself is very low, making it impossible to apply the protective film. In addition, since the film cannot be obtained through chemical bonding, it must be heated and sintered at a high temperature of 200 degrees or higher. Since it is impossible to develop a material that can be used for transparent polymers such as PC and PMMA.

In addition, Korean Laid-Open Patent No. 2008-0093625 proposes a technique for improving dispersibility of nanodiamond powder using a silane coupling agent. However, PTFE coating agent is improved by improving adhesion between nanodiamond and PTFE through a silane coupling agent. It is not considered that the wear resistance and the low friction of the same can be further improved simultaneously.

In addition, Japanese Patent Application Laid-Open No. 2008-0183640 discloses a step of preparing and preparing a fine diamond powder having an average particle diameter of 1000 nm or less in which the surface layer of the diamond particles is surface-modified by hydrophilization, hydrophobization, or non-diamond carbonization. A diamond-dispersed synthetic resin molding material and a method for producing the same are proposed, which include dispersing modified diamond particles in a molding raw material body including monomers or oligomers of the molding resin and polymerizing monomers or oligomers of the molding resin into a resin molding. In Korean Laid-Open Patent No. 2008-0093625, nanodiamonds are mixed with an organic solvent and then bead milled to prepare a nanodiamond dispersion, a silane compound is added to the dispersion, a mixed coating solution is prepared, and an aluminum alloy is coated and then heat treated. Coating method comprising the steps Afterwards. However, these techniques will improve the surface properties by using a diamond particles but mothayeo not satisfy all of the various physical property improvements and compatibility, surface adhesiveness, and durability were room for improvement.

Accordingly, in the present invention, in order to solve the problems of the prior art, as a follow-up study of Korea Patent Publication No. 2010-0103242, while studying the method to maximize the physical properties by applying the diamond particles more effectively, the specific component in the silane treatment solution When added to know that there is a significant physical properties improvement effect was completed the present invention.

Accordingly, an object of the present invention is to provide a method for preparing a resin coating agent using diamond particles in which diamond particles are dispersed and greatly improved in scratch resistance, weather resistance, UV resistance, and stain resistance.

In addition, an object of the present invention is to provide a resin coating method in which the diamond is coated with a resin coating agent to control the particle size of the coating liquid in which the particles are dispersed and the dispersion effect is excellent to provide excellent scratch resistance, stain resistance and weather resistance. .

In order to solve the present invention as described above, the present invention is a first step of dispersing nanodiamond powder in a solvent using bead milling; A second step of adding and reacting a silane coupling agent having an acrylate group, an amine group, or a mercapto propyl group with an organic functional group to the dispersion solution obtained in the first step; And a third step of mixing the silane addition solution obtained in the second step with a monomer, an oligomeric compound or a silane precursor.

In another aspect, the present invention provides a coating method of the resin coating agent to coat the resin prepared as described above to the resin and to cure using ultraviolet rays or heat after heat drying.

The resin coating agent prepared according to the present invention not only changes the dispersing property of the nanodiamond powder due to the use of the lan coupling agent, but also improves the bond between the nanodiamond and the base material, thereby showing an improved hardness than before. It is possible to prevent the occurrence of scratches on the surface of the coating film.

In addition, when coating the coating prepared according to the present invention, while simplifying the complicated manufacturing process of the existing coatings, it is possible to prepare a transparent coating with improved wear resistance, chemical resistance and weather resistance.

In addition, the coating agent prepared according to the present invention can improve the transparency of the coating film by reducing the size of the nanodiamond particles through the bead milling and silane coupling agent treatment, the hydrophilic tendency due to the hydrophobic nature of the silane coupling agent and the nanodiamond Branches are combined with acrylic bases to prevent contamination by sweat, fingerprints and the like.

In addition, when coating the coating agent prepared according to the present invention can suppress the yellowing and whitening of the coated product due to sunlight exposure can maintain the transparency and improve the merchandise.

1 is a graph of FT-IR analysis results of nanodiamond particles before silane treatment and nanodiamond particles after silane treatment according to Examples and Comparative Examples 1 and 2 of the present invention.
2 is a graph of zeta potential measurement results according to Example 1 and Comparative Example 1 of the present invention.
Figure 3a is a photograph showing the interface after the friction test on the specimen without the addition of nanodiamond particles, Figure 3b is a photograph of the interface after the friction test on the specimen added with 0.8% nanodiamond, Figure 3c is a silane-treated nano A photograph of the interface after a friction test on 0.8% diamond added specimens.
4 is UV-visibility transmittance test data for an embodiment according to the present invention.
5 is a graph showing the results of measuring the micro-Vickers hardness of Example, Comparative Example 1 and Comparative Example 2 according to the present invention.
Figure 6 is a graph showing the wear resistance comparison results for the coated product and the commercial product according to the embodiment of the present invention.

Hereinafter, the present invention will be described in detail as an embodiment.

The present invention comprises a first step of dispersing nanodiamond powder in a solvent using bead milling; A second step of adding and reacting a silane coupling agent having an acrylate group, an amine group, or a mercapto propyl group with an organic functional group to the dispersion solution obtained in the first step; And a third step of mixing the silane addition solution obtained in the second step with a monomer, an oligomer compound, or a silane precursor.

In the first step in which the nanodiamond powder of the present invention is dispersed in a solvent using bead milling, the nanodiamond powder is dispersed in a polar or nonpolar solvent. For example, a powder having a particle size of 10 to 400 nm may be used as the nanodiamond powder, and alcohol, water, or a mixture thereof may be used as the solvent. As alcohol, isopropyl alcohol or butyl alcohol may be preferably used. More preferably, for the siloxane reaction of the silane coupling agent, 0-10% of distilled water may be mixed with the alcohol, followed by milling by titrating to pH 3-10 using an acid or a base. When the solution is acidic, it promotes the reaction of the silane coupling agent by water in the two-step process, keeps the particle size small when milling, and improves dispersion stability of the solution. You can adjust the size of the. The nanodiamond powder may be added in an amount of 1 to 30 parts by weight based on 100 parts by weight of the solution prepared with the solvent. When the nanodiamond powder is less than 1 part by weight with respect to 100 parts by weight of the solution, the milling efficiency is low, and the particles are more than 30 parts by weight. There is a disadvantage that the milling efficiency is lowered due to the increase in density.

The diameter of the beads used for the milling is preferably 0.1 ~ 1mm. When the diameter of the beads is less than 0.1mm, the milling efficiency is good, but the separation is difficult due to the osmotic pressure generated between the beads after milling, and the loss is large. The material of the bead should be made of a ceramic material because the amount to be worn by the diamond is small, more preferably zirconia beads can be used.

Nanodiamond prepared by the bead milling through the second step of adding and reacting a silane coupling agent having an acrylate group, an amine group, or a mercapto propyl group as an organic functional group to the dispersion solution obtained in the first step in the present invention The solution is treated with a silane coupling agent for more effective dispersion and improved surface properties. The silane treatment may use a method of stirring the prepared diamond mixed solution at 60 to 120 ° C. for 4 to 10 hours when the solution does not contain water, and maintains the acidity of the solution at pH 3 to 6 when water is added. After the silane coupling agent may be added in small portions.

In this case, the amount of the silane coupling agent added mainly depends on the surface area according to the particle size of the nanodiamond powder, but 0.1 to 10 parts by weight based on 100 parts by weight of the nanodiamond powder is sufficient to form a single layer on the surface of most nanodiamond particles. If it is less than 0.1 part by weight, a single layer may not be formed on all of the nanodiamond particles, and if it is more than 10 parts by weight, an excess of silane will be left.

The reason why the reaction temperature is maintained at 60 to 120 ° C. when the silane coupling agent is reacted is to induce a hydrolysis reaction of the silane coupling agent to effectively surround the nanodiamond particles. Because it is not. In addition, when the stirring time is less than 4 hours, the hydrolysis reaction is insufficient, and when more than 10 hours, the solvent is volatilized, thereby causing a problem that the content ratio of the nanodiamond powder to the solvent is greatly changed. The reason why the state of the solution is kept acidic when using a solution to which water is added is to promote the hydrolysis reaction by water during the reaction of the silane coupling agent.

As the silane coupling agent used in the present invention, those having a methoxy group as the first organic functional group and an acrylate group, an amine group, or a mercaptopropyl group as the second organic functional group may be preferably used. As a preferred example thereof, Methacryloxy propyl trimethoxy silane may be used. This silane coupling agent contains a methoxy group and a silane group excellent in binding strength with nanodiamond particles as an inorganic functional group, and has an acrylic group on the opposite side, and exhibits very good bonding property with an acrylic base.

In the third step of mixing the silane addition solution obtained in the second step of the present invention with a monomer, oligomeric compound or silane precursor, the silane-treated nanodiamond dispersion solution is mixed with an acrylic monomer or oligomer or silane precursor to prepare a coating agent. do. Unlike the prior art such as Korean Patent Publication No. 2010-0103242, such a technology uses a base material having transparency, and since the acrylic group of the monomer, the acrylic group of the silane, and the methoxy group are bonded through copolymerization, the conventional PTFE-based thermal sintering type Compared with the polymer, a stronger curing effect can be shown. This is a technology introduced to realize a transparent coating technology for improving wear resistance of transparent plastic materials (PC, PMA, etc.), for example, to replace glass in automotive exterior parts.

At this time, as the acrylic monomer or oligomer to be used, any material that forms a urethane or acrylic polymer through chemical reaction may be used, and preferably, DPHA (Dipentaerythritol Hexaacrylat) or PETA (Pentaerythritol Tetraacrylate) may be used. As the silane precursor, one selected from (3-glycidoxypropyl) trimethoxysilan, (3-Mercaptopropyl) trimethoxysilane, (3-Aminopropyl) trimethoxysilane, and 3-Methacryloxy propyl trimethoxy silane can be used. Preferably, 3-Methacryloxy propyl trimethoxy silane may be used. These monomers or oligomers or silane precursors are used for the purpose of improving the adhesion between nanodiamonds and the polymer matrix to improve the physical properties of the coating layer itself and to impart hydrophilicity or water repellency to the coating surface. It can be used in 0.1 to 10 parts by weight based on 100 parts by weight. If it is less than 0.1 part by weight, a single layer may not be formed on all of the nanodiamond particles, and if it is more than 10 parts by weight, an excess of silane will be left.

According to the present invention preferably in the third step, the silane treated diamond is to be mixed at 0.1 to 5% by weight in the total coating. When the mixing amount is less than 0.1% by weight, the nanodiamond content is insufficient, so that the surface strengthening effect is lowered, and when the amount exceeds 5% by weight, the strengthening effect tends to decrease again.

According to the present invention, an ultraviolet curing agent, a leveling agent, an antifoaming agent, a UV stabilizer, a UV absorber, and the like are added as additives in the mixing process of the third process, and can be adjusted to a viscosity suitable for coating by controlling the amount of the solvent.

As described above, the coating agent prepared according to the present invention includes a methoxy group and a silane group having a high bonding force with nanodiamond particles as the silane coupling agent as an inorganic functional group. good. In particular, the acrylic monomer or oligomer used in the third process and the silane precursor can obtain improved bond strength compared to the existing through the copolymerization reaction and diffusion between the silane precursor and the acrylate of the monomer during the curing reaction. As a result of the improved bonding strength, the diamond particles are strongly fixed inside the polymer, thereby greatly improving the hardness, toughness and scratch resistance of the base material. In addition, since the size of the nanodiamond particles is kept small through the silane treatment, the transparency is excellently maintained.

On the other hand, the coating agent prepared according to the present invention is coated in a conventional method, such as spin coating, bar coating, shedding coating, gravure coating, spray coating, etc., when the coating on the resin and after the coating is completed by UV drying after heat drying Alternatively, the coating may be obtained by curing with heat to obtain a desirable coating state. Preferably, after the coating is completed, the solvent may be volatilized by infrared drying and then coated by curing with UV irradiation apparatus for 10 to 60 seconds.

After the coating is coated, the surface of the coating is formed on the plastic molded article in a state of coating that has a scratch prevention effect through reinforcement of surface hardness and remarkably enhanced weather resistance and stain resistance.

As a resin to which the coating of the coating agent according to the present invention is applied, for example, it is applicable to resins such as PC, PMMA, PAI, ABS, PE, and the like, for example, transparent coatings such as plastic materials and high-gloss coatings for replacing automotive glass materials. It can be preferably applied to the molded article required.

Hereinafter, the present invention will be described in detail with reference to examples. However, the present invention is not limited to the examples.

Example

After the nanodiamond powder was mixed with butyl alcohol at a ratio of 4wt%, milled with 0.3mm diameter zirconia beads for 4 hours to prepare a dispersion solution, and then, 3Methacryloxy propyl trimethoxy silane having a weight ratio of 4 wt. After the addition, the mixture was stirred for 5 hours in a state of hot water at 70 ° C.

As the acrylic coating solution, a polyfunctional acrylate coating commonly used as a commercial hard coating agent was used, 30 g of DPHA (Dipentaerythritol hydroxy pentaacrylate), 10 g of PETA (Pentaerythritol triacrylate), Irgacure 184 3 g as a photoinitiator, and 10 g of butyl acetate as a solvent. The diamond dispersion solution prepared above was mixed with 2, 4, 6, 8, 10, 20 and 30 g, respectively.

In order to make the viscosity the same, butyl alcohol was mixed with 28, 26, 22, 20, 10, and 0g, respectively, and then stirred with a paste mixer to prepare a coating, and a UV additive was added to prepare a coating.

Comparative Example 1

A coating agent was prepared in the same manner as in Example, but the coating agent was prepared without adding nanodiamond particles.

Comparative Example 2

A coating agent was prepared in the same manner as in Example, but the coating agent was prepared by adding nanodiamond particles not treated with silane.

Comparative Example 3

The coating process was carried out using the PTFE coating solution as used in the same procedure as in the above example, but was disclosed in Korea Patent Publication No. 2010-0103242.

Experimental Example

Spin coating the coating agent of the prepared example at 1000rpm and then dried for 10 seconds using a 70 ℃ infrared lamp and then cured for 3 minutes using a 300W UV lamp. The coated specimen contained 0.2, 0.4, 0.6, 0.8, 1.0, 2.0, 3.0 weight ratio of diamond solids relative to the coating solution.

Coating and curing of the prepared Comparative Examples 1 and 2 in the same manner.

When the coating liquid prepared by the above method is uniformly applied on the PC by spin coating or spray coating, it is possible to obtain a transparent and wear resistant coating layer.

As described above, the physical properties of the specimens according to Examples (silane-treated ND 1wt%, 3wt%), Comparative Example 1 (no addition, ND 0wt%), and Comparative Example 2 (ND 1wt%, ND 3wt%) As a result, pencil hardness, contamination, adhesion test measurement results are shown in Table 1, and wetting angle measurement results in Table 2, respectively.

In the experiment, the measurement of each physical property was measured by the following method.

(1) pencil hardness; ASTM-D2197

(2) heat resistance; 10 hours at 70 ℃ Furnace

(3) Adhesiveness: ASTM D3359, cross hatch cut test

(4) Immersion test: Name pen, ballpoint pen, and Dylon's MP8 dye for 10 hours at 50 ℃

(5) Wetting Angle Picture: Use the method shown in the following Table 3.

In addition, FT-IR analysis was performed on the nanodiamond particles before the silane treatment and the nanodiamond particles after the silane treatment, and the results are shown in the graph of FIG. 1. In this case, the silane treatment resulted in better adhesion and the like.

Zeta potential measurement results according to the Example and Comparative Example 1 was much better for the solution subjected to the silane treatment, as shown in the graph of FIG. The high zeta potential difference increases the stability of the particles in the solvent and serves to inhibit the precipitation of the particles upon long term storage.

In addition, as a result of experiments to confirm that the nanodiamond particles for Examples and Comparative Examples 1 and 2 have excellent scratch resistance, the interface after the friction test on the specimen (Comparative Example 1) is not added to the nanodiamond of Figure 3a , Interface after the friction test on the specimen added with 0.8% nanodiamond (Comparative Example 2), and the interface after the friction test on the specimen added with 0.8% silane-treated nanodiamond (Example) of Figure 3c In each photo for Comparative Example 1 it can be seen that the coating film is torn in a large range due to the low coating film strength, in the case of Comparative Example 2 it was confirmed that the coating film falling off due to the low adhesion between the nanodiamonds. In the case of Figure 3c corresponding to an embodiment of the present invention, the surface state was maintained without falling off into a lump, and the most excellent physical properties were confirmed.

4 is UV-visibility transmittance test data. In general, in order to obtain the strengthening effect of nanodiamonds, a particle size of 100 to 300 nm is required. However, when particles of such a size are added, the transparency tends to be lowered through scattering. In the case of milling and silane treatment, the particle size is about 200 nm, but the transparency is more than 90% due to the high dispersion stability. Confirmed that it can.

In the graph of FIG. 5 showing the results of the micro-Vickers hardness, the silane-treated example of the present invention showed the best physical properties, and the wear-resistant comparison result of the example of FIG. Showed characteristics.

Claims (12)

A first step of dispersing the nanodiamond powder in a solvent using bead milling; A second step of adding and reacting a silane coupling agent having an acrylate group, an amine group, or a mercapto propyl group with an organic functional group to the dispersion solution obtained in the first step; And a third step of mixing the silane addition solution obtained in the second step with a monomer, an oligomer compound, or a silane precursor. The method for producing a resin coating agent according to claim 1, wherein the solvent is a low alcohol having 1 to 3 carbon atoms. The method of claim 1, wherein the nanodiamond powder is milled into beads having a diameter of 0.1 to 1 mm. The method of claim 1, wherein the nanodiamond powder is dispersed in an amount of 0.1 to 30.0 parts by weight based on 100 parts by weight of the solvent. The method of claim 1, wherein the silane coupling agent is mixed at 0.1 to 10.0 parts by weight based on 100 parts by weight of the nanodiamond powder. The method of claim 1, wherein the silane coupling agent is methacryloxy propyl trimethoxy silane. The method of claim 1, wherein the dispersion solution and the silane coupling agent are stirred at 60 to 90 ° C for 4 to 10 hours. The method for producing a resin coating agent according to claim 1, wherein DPHA and PETA are mixed and used as the monomer, oligomeric compound or silane precursor. The method of claim 1, wherein the monomer, oligomeric compound or silane precursor is used in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of nanodiamond used in the silane addition solution. The coating method of claim 1, wherein the coating agent prepared according to claim 1 is coated on a resin and cured using ultraviolet rays or heat after heat drying. The coating method according to claim 10, wherein the coating is coated by spin coating, bar coating, spill coating, gravure coating or spray coating. The coating method according to claim 10, wherein the coating method comprises a method of volatilizing the solvent through infrared ray drying after the coating is completed, followed by curing for 10 to 60 seconds through an ultraviolet irradiation device.

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