KR101084680B1 - Hard coating agent for surface modification of transparent plastic and method of manufacturing same - Google Patents

Abstract

The present invention comprises the steps of mixing a metal alkoxide and a silane coupling agent (step A); Preparing a mixed solution by adding an ultraviolet curable oligomer, a polyfunctional monomer and a solvent to the mixture prepared in step A (step B); And adding a photoinitiator to the mixed solution prepared in step B and stirring (step C), a method of preparing a UV curable hard coating agent for transparent plastic surface modification, and a UV curable hard coating agent for transparent plastic surface modification prepared accordingly. It is about. The hard coating agent for transparent plastic surface modification according to the present invention is excellent in transmittance, and can improve the adhesion between the transparent plastic and the coating film while improving the transparent plastic surface hardness.

Description

Hard coating agent for modificating the surface of transparent plastics and method for preparing for the same}

The present invention relates to a hard coating agent for transparent plastic surface modification and a method for manufacturing the same, and more particularly, to improve the scratch resistance of the surface of the transparent plastic and at the same time to improve the adhesion between the transparent plastic and the coating film and a manufacturing method thereof It is about.

In general, transparent plastics (PMMA, PET, PC) are lightweight, easy to form by heat, and excellent in durability and chemical resistance, so they have a wide range of application to electric parts such as automobiles, computers, mobile phones, and general household products. . The most commonly used transparent plastic is polycarbonate (PC), which has a light transmittance of about 90%, and is excellent in impact resistance, and is widely used in fields such as automobiles, architecture, ornaments, and optical lenses. However, these plastic resins have a soft surface, unlike glass, and thus are easily scratched or weak in chemical resistance. In order to solve these drawbacks, a method of hard coating on a plastic surface is commonly used, which forms a high hardness film on the plastic surface to prevent damage from appearance due to scratches on the surface and to improve chemical resistance. I could make it. As such a hard coating agent, an organic-inorganic hybrid coating agent prepared by the sol-gel method has been used in various ways.

The sol-gel method is a method for economically producing a functional coating solution, metal oxide nanoparticles, and functional ceramics through a hydrolysis reaction and a polycondensation reaction in a solution using high purity metal alkoxide as a precursor. In this method, a product having a high chemical uniformity can be obtained, and in particular, an organic-inorganic hybrid having an intermediate characteristic of an inorganic material and an organic material can be easily prepared by adding and reacting an organic material with an inorganic precursor. In this case, by forming a composite in which the inorganic material and the organic material are uniformly mixed in nano units, a material having a new characteristic having both the advantages of wear resistance and transparency of the inorganic material and the flexibility and moldability of the organic material can be obtained.

Schmidt prepared an organic-inorganic hybrid solution by reacting nanoparticles such as alumina, titania and zirconia with organic materials such as silane, carboxylic acid or β-diketan using a sol-gel method. In addition, Winkler et al. Prepared an organic-inorganic hybrid solution by reacting inorganic materials such as silica, alumina and zirconia with GPTMS (glycidoxypropyl trimethoxysilane) using the sol-gel method. Then, the use as a hard coating agent for PC base materials was examined. Tanglumlert et al. Prepared an organic-inorganic hybrid solution using fumed silica and GPTMS as a starting material by the sol-gel method, and then dip-coated the surface of the coating film on a polymethyl methacrylate (PMMA) substrate. Reported increasing with increasing GPTMS content.

Korean Laid-Open Patent Publication No. 2008-0035218 discloses a coating composition used for a plastic lens, and the coating composition includes an organo silane compound, an aluminum complex, an inorganic oxide, a common solvent, and a solvent, and is wear-resistant and dyeable. It is an object of the present invention to provide a coating composition having excellent transparency.

Korean Patent No. 0316731 discloses a composition comprising 10 to 90% by weight of a hydrolyzed hydrate of a silicon alkoxide compound, and a metal (M _I ) alkoxide compound and an organic solvent using a metal (M _II ) salt hydrate as a catalyst. It contains 90 to 10% by weight of a metal alkoxide hydrate prepared by decomposition, and the molar ratio of M _I / M _{II in} the composition is disclosed for an optical coating composition, the coating composition is a storage stability and It aims at improving film forming stability and improving weather resistance and scratch resistance.

Organic-inorganic hybrid coating and coating coating composition that can be used in the above-mentioned transparent plastic coating is still insufficient to form a coating layer having satisfactory properties, low hardness of the coating film, low adhesion of the plastic substrate and the coating film Therefore, there is a problem to commercialize.

The present inventors are studying a more effective way to solve this problem, the coating film on the surface of the transparent plastic by applying a hard coating agent prepared by adding a composite silane coupling agent mixed with GPTMS and MPTMS to the alumina / zirconia complex sol When forming a, it was found that the transmittance of the coating film formed, the scratch resistance and the adhesion to the transparent plastic is excellent to complete the present invention.

Disclosure of Invention An object of the present invention is to provide a hard coating agent for surface modification of a transparent plastic and a method of manufacturing the same, which not only improve scratch resistance of the transparent plastic but also improve adhesion to the transparent plastic.

In order to achieve the above object, the present invention comprises the steps of preparing an alumina / zirconia complex sol (step 1); Mixing a silane coupling agent, a metal alkoxide and a solvent with the alumina / zirconia composite sol prepared in step 1 and then stirring (step 2); And adding a crosslinking agent to the mixture stirred in step 2 and stirring (step 3).

In addition, the present invention comprises the steps of mixing a metal alkoxide and a silane coupling agent (step A); Preparing a mixed solution by adding an ultraviolet curable oligomer, a polyfunctional monomer and a solvent to the mixture prepared in step A (step B); And adding a photoinitiator to the mixed solution prepared in step B and stirring (step C).

The present invention can improve the weak scratch resistance, which is a problem of transparent plastics, which are widely used as glass substitutes in recent years, and have improved adhesion to transparent plastics. It can provide a manufacturing method.

1 is a flowchart of a process for preparing an alumina / zirconia complex sol.
Figure 2 is a SEM photograph taken for the coating film formed on the PMMA sheet in Example 1 of the present invention.
3 is a photograph taken after the hardness test to 5H ~ 6H for the coating film formed on the PMMA sheet.
Figure 4 is a SEM photograph of the cross-sectional coating film between the stretch after the hardness test at 6H for the coating film formed on the PMMA sheet.

Hereinafter, the present invention will be described in detail through specific examples.

Step 1 is a step of preparing an alumina / zirconia complex sol. 1 is a flowchart of a process for preparing an alumina / zirconia complex sol.

As shown in FIG. 1, the alumina / zirconia complex sol is mixed with distilled water using aluminum isopropoxide (AIP) as a starting material, and then zirconium oxy is mixed in the mixture of aluminum isopropoxide and distilled water. It is prepared by the addition of hydrochloric acid for the peptizing action in the step of stirring and adding a chloride octahydrate (zirconium oxychloride octahydrate) is prepared by stirring.

Aluminum isopropoxide and distilled water are preferably mixed in a 1: 100 molar ratio.

Step 2 is a step of mixing the silane coupling agent, the metal alkoxide and the solvent in the alumina / zirconia composite sol prepared in step 1 and then stirring. In the stirring process, since the mixed coating solution is affected by the environmental atmosphere, it is preferable to use a glove box in a vacuum state under a nitrogen atmosphere.

The alumina / zirconia composite sol prepared in Step 1 is preferably used in a weight ratio of 1: 2 with the silane coupling agent. When the alumina / zirconia composite sol is used with the silane coupling agent in an amount greater than 1: 2, a problem may occur in that the surface strength is lowered.

The silane coupling agent may be a compound silane coupling agent using GPTMS (glycidoxypropyl trimethoxysilane) alone or a mixture of GPTMS (glycidoxypropyl trimethoxysilane) and MPTMS (methacryloxypropyl trimethoxysilane). Although it can be used, it is preferable to use a composite silane coupling agent in which GPTMS and MPTMS are mixed in terms of shortening the curing time and increasing adhesion.

The composite silane coupling agent is preferably used by mixing GPTMS and MPTMS in a weight ratio of 1: 1 to 3: 4. In the composite silane coupling agent, if the weight ratio of MPTMS mixed with GPTMS is less than 1: 1, the scratch resistance of the coating film may be weakened. If the weight ratio of MPTMS mixed with GPTMS is more than 3: 4, the coating film is uneven. Problems may arise that result in opaque white haze.

As an inorganic substance contained in a hard coat agent, a metal alkoxide can be used. Tetraethyl orthosilicate may be used as the metal alkoxide, but is not limited thereto. It is preferable to use ethanol or isopropanol as a solvent.

Step 3 is a step of adding and stirring a crosslinking agent to the mixture stirred in step 2. Ethylenediamine may be used as the crosslinking agent, but is not limited thereto.

The present invention provides a hard coating agent for modifying the transparent plastic surface prepared according to the above-described method for preparing a hard coating agent. The hard coating agent of the present invention is used to improve the scratch resistance of the transparent plastic, and also has excellent adhesion with the transparent plastic.

The hard coating agent of the present invention is preferably used for surface modification of polymethyl methacrylate (PMMA). But it is not limited thereto.

In addition, the present invention,

Mixing the metal alkoxide and silane coupling agent (step A);

Preparing a mixed solution by adding an ultraviolet curable oligomer, a polyfunctional monomer and a solvent to the mixture prepared in step A (step B); And

It provides a method for producing a UV-curable hard coating agent for transparent plastic surface modification comprising the step (step C) by adding a photoinitiator to the mixed solution prepared in step B and stirring.

Hereinafter, a method for preparing a UV-curable hard coating agent for surface modification of a transparent plastic of the present invention will be described in detail step by step.

Step A is a step of mixing the metal alkoxide and the silane coupling agent.

MPTMS may be used as the silane coupling agent, and tetraethyl allosilicate may be used as the metal alkoxide.

Step B is a step of preparing a mixed solution by adding an ultraviolet curable oligomer, a polyfunctional monomer and a solvent to the mixture of the metal alkoxide and the silane coupling agent prepared in step A.

The ultraviolet curable oligomer may use a six-functional urethane acrylate, but is not limited thereto.

As the polyfunctional monomer, a bifunctional acrylate (HDDA) represented by the following formula (1) and a trifunctional acrylate (TMPTA) represented by the formula (2) may be used.

Step C is a step of adding and stirring a photoinitiator to the mixed solution prepared in step B.

As photoinitiator, 1-hydroxy-cyclohexyl-phenyl ketone can be used.

The present invention provides a UV-curable hard coating agent for transparent plastic surface modification prepared according to the above-described method for producing a UV-curable hard coating agent for transparent plastic surface modification. UV curable hard coating agent for transparent plastic surface modification of the present invention is preferably applied to polycarbonate (PC).

Hereinafter, specific manufacturing examples will be described.

Aluminum isopropoxide (AIP, 98%, Al (OC ₃ H ₇ ) ₃ , Aldrich) was used as a starting material, and the aluminum isopropoxide was mixed with distilled water at a molar ratio of 1: 100, and this solution was added to the solution. Zirconium oxychloride octahydrate (ZrOCl ₂ 8H ₂ O) was added and hydrolysis was carried out at 90 ° C. for 1 hour. Hydrochloric acid (HCl, 35.0%, DUKSAN Chemical) was added to this solution for peptizing in the middle of hydrolysis, followed by stirring for 24 hours at 90 ° C., resulting in a very transparent and stable alumina / zirconia complex sol. Was prepared.

For surface modification of the alumina / zirconia composite sol prepared as above, GPTMS (98%, Aldrich Chemical), which is a silane coupling agent, and TEOS (tetraethyl orthosilicate, 98%, Aldrich Chemical), which are inorganic components, were mixed for 1 hour at 50 ° C. After stirring, the mixture was stirred using a glove box under vacuum at room temperature for 24 hours under a nitrogen atmosphere. Thereafter, 0.05 mol of a crosslinking agent, ethylenediamine (99%, Aldrich Chemical) was added to the solution, followed by stirring for 1 hour, thereby preparing a surface-modified final coating agent.

Since the coating agent prepared in Example 1 is greatly influenced by the environmental atmosphere to be coated, it is coated on a PMMA sheet (Kumjoung Industry Co., LTD) of 1.5 mm thickness and 70 mm x 50 mm size using a glove box in a nitrogen atmosphere under vacuum. It was. After coating the coating solution on the PMMA substrate, the first drying was carried out at room temperature for 10 minutes, and the second drying was performed at 140 ° C. for 2 hours as a second curing, and SEM images of the formed coating film were taken. 2 is shown. Referring to Figure 2, it can be seen that the alumina / zirconia coating film is formed on the PMMA sheet. Physical properties of the formed coating film were measured by the following physical property measurement methods.

1) pencil hardness measurement

Pencil hardness is a pencil hardness tester (CORE TECH, Total solution for laboratory) by inserting the pencil hardness measuring pencil at 45 ^o angle, while applying a constant load (0.5kg) to the coating film formed on the PMMA sheet in Experimental Example 1 while pushing it Measured. As a pencil, Mitsubishi pencil was used, and pencils showing strengths such as H-9H, F, HB, and B-6B were used. As a result of the measurement, the coating film formed on the PMMA sheet in Experimental Example 1 showed an excellent pencil hardness of 5H. In addition, in Experimental Example 1, the hardness of the coating film formed on the PMMA sheet was tested at 5H to 6H under the conditions of 500g and 1kg, and the results are shown in Table 1 and shown in FIGS. 3 and 4. Figure 3 is a photograph taken after the hardness test at 5H ~ 6H for the coating film formed on the PMMA sheet, Figure 4 is taken after the hardness test at 6H for the coating film formed on the PMMA sheet cross-sectional film coating between stretch SEM picture.

Pencil hardness weight  PMMA sheet coating film 5H 500 g Good 1 kg Good 6H 500 g scratch 1 kg scratch

As shown in Table 1, Figure 3 and Figure 4, it can be seen that the coating film formed using the hard coating agent of the present invention has an excellent hardness of 5H.

2) transmittance measurement

In Experimental Example 1 in the visible region, the UV-visible spectrometer (UV-2450, Shimadzu) was used to measure the transmittance of the coating film formed on the PMMA sheet from 200 nm to 800 nm. In Experimental Example 1, the transmittance of the coating film formed on the PMMA sheet was 92%, indicating a similar transmittance tendency to that of the uncoated PMMA.

3) adhesion

Based on ASTM D 3359, after making a checkered groove on the coating film with a cutter, the 3M tape was adhered well and peeled off several times with a constant force to observe the adhesion between the coating layer and the substrate. 100 squares were made by cross-cutting 11 × 11 at 1 mm intervals on the surface of the coated support, and the surface was evaluated by rapidly pulling a tape (3M Tape) on the surface. If the number of remaining eyes is 100, 5B, 95 or more are 4B, 85 or more are 3B, 65 or more are 2B, 35 or more are 1B, and less are 0B. In Example 1 of the present invention, a test of 10 times on the coating film formed on the PMMA sheet showed excellent adhesion of 5B.

Claims (8)

Mixing the metal alkoxide and silane coupling agent (step A);
Preparing a mixed solution by adding an ultraviolet curable oligomer, a polyfunctional monomer and a solvent to the mixture prepared in step A (step B); And
Adding a photoinitiator to the mixed solution prepared in step B and stirring (step C)
Method for producing a UV curable hard coating agent for surface modification of a transparent plastic comprising a.
The method of claim 1,
The silane coupling agent is methacryloxypropyl trimethoxysilane (MPTMS), characterized in that the manufacturing method of UV-curable hard coating agent for transparent plastic surface modification.
The method of claim 1,
The metal alkoxide is a tetraethyl allosilicate, characterized in that the manufacturing method of UV-curable hard coating agent for transparent plastic surface modification.
The method of claim 1,
The UV-curable oligomer is a method of producing a UV-curable hard coating agent for transparent plastic surface modification, characterized in that the six-functional urethane acrylate.
The method of claim 1,
The multifunctional monomer is a bifunctional acrylate (HDDA) represented by the following formula (1) and trifunctional acrylate (TMPTA) represented by the formula (2) The method of manufacturing a UV curable hard coating agent for surface modification of a transparent plastic, characterized in that :
[Formula 1]

(2)

.
The method of claim 1,
The photoinitiator is a 1-hydroxy-cyclohexyl-phenyl ketone, characterized in that the UV curable hard coating agent for the surface modification of plastics.
The method of claim 1,
The transparent plastic is a polycarbonate (PC) characterized in that the manufacturing method of the UV-curable hard coating agent for the transparent plastic surface modification.
A UV curable hard coating agent for surface modification of a transparent plastic prepared according to any one of claims 1 to 7.

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