KR20240097409A - Organic-Inorganic Hybrid Composition for Hardcoating, Hardcoating Film thereby and Cover Window Including the Film - Google Patents

Abstract

The present invention provides an organic-inorganic hybrid composition for hard coating that exhibits excellent hardness, anti-fouling properties, light transmittance, and adhesion without forming a separate anti-fouling layer or anti-reflection layer, and does not generate cracks when forming a curved surface, so it has excellent curved surface processability, and the organic-inorganic hybrid composition formed by the composition It relates to a hard coating film and a cover window to which the hard coating film is applied, more specifically CH ₃ (CH ₂ ) ₈ CH ₂ Si(OR ¹ ) ₃ ; R ² Si(OR ³ ) ₃ ; and Si(OR ⁴ ) ₄ ; It relates to a hard coating composition comprising a siloxane resin composed of derived structural units, a hard coating film formed by the composition, and a cover window to which the hard coating film is applied.
At this time, R ¹ , R ³ and R ⁴ are each independently a C1 to C4 linear or branched alkyl group, and R ² is a C1 to C4 linear, branched or alicyclic alkyl group in which an epoxy or acrylic group is substituted, or a substituted or It is an unsubstituted aryl group of C6 to C12, or a linear or branched alkyl group of C1 to C4 having an alkene group.

Description

Organic-inorganic hybrid composition for hard coating, hard coating film thereby, and cover window to which the hard coating film is applied {Organic-Inorganic Hybrid Composition for Hardcoating, Hardcoating Film thereby and Cover Window Including the Film}

The present invention provides an organic-inorganic hybrid composition for hard coating that exhibits excellent hardness, anti-fouling properties, light transmittance, and adhesion without forming a separate anti-fouling layer or anti-reflection layer, and does not generate cracks when forming a curved surface, so it has excellent curved surface processability, and the organic-inorganic hybrid composition formed by the composition It relates to a hard coating film and a cover window to which the hard coating film is applied.

A display device includes a display panel with a plurality of pixels for displaying an image, and a cover window formed on the display panel to protect the display panel from external shock or contamination. Cover windows require high hardness characteristics to prevent surface scratches, high strength characteristics to prevent damage from external impacts, and excellent optical characteristics to not damage or distort the image displayed from the fascia panel. Recently, as the number of displays operated by touch play has expanded, anti-fouling properties are also required to prevent image quality or visibility from deteriorating due to color transfer from hands. In addition, as the application fields of display devices become more diverse, curved surface machinability is also required to break away from the flat structure and facilitate processing into various shapes. For example, displays applied to automobiles are not only conventionally simple square navigation products, but products with the entire front part implemented as a central information display (CID, Center Information Display) are being released or are expected to be released. Accordingly, it is necessary to manufacture a cover window that goes beyond the square plane and is free to form various shapes and curves, and can easily be expanded into a large area.

Tempered glass, which has been mainly used as a material for conventional cover windows, has the advantage of being resistant to scratches and having excellent optical properties due to its high strength characteristics. However, because it is relatively heavy, it is difficult to apply to displays that require light weight, such as portable devices or eco-friendly cars, and it is vulnerable to shock and has the property of scattering when impacted, which can cause secondary damage. In addition, the difficulty in processing curved or irregular shapes does not meet the needs of the recent display market.

Recently, research on implementing cover windows using plastic materials has been continuously conducted to solve problems with tempered glass materials. Representative plastic materials used in cover windows include polycarbonate (PC), polymethylmethacrylate (PMMA), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyethylene naphthalate (PEN). Examples include polyethersulfone (PES), and transparent polyimide (CPI; colorless polyimide) is also in the spotlight as a cover window for flexible displays. Plastic materials are promising as a replacement for glass due to their lightness, impact resistance, transparency, and flexibility, but their optical properties, including impact resistance, scratch resistance, and light transmittance, are insufficient compared to glass.

In order to compensate for these shortcomings, various attempts are being made to improve the physical properties by forming a hard coating layer on the surface of the plastic material. A separate functional layer is formed on the hard coating layer to complement the characteristics required for the cover window. For example, an anti-reflection layer and/or an anti-glare layer can improve the optical properties of the cover window. The formation of an antifouling layer can prevent contamination of the surface of the cover window and reduce visibility or aesthetics.

However, since there are conflicting characteristics among the characteristics required for a cover window, it is not easy to satisfy all characteristics simultaneously with one layer. For example, when high hardness characteristics are satisfied through hard coating, processability may be reduced, which may lead to cracks occurring during curved surface processing or reduced impact resistance. When flexibility is given to the hard coating layer to improve processability, optical properties deteriorate and hardness decreases. For this reason, a multi-layer laminated structure is sometimes formed to satisfy various characteristics. In addition, it is difficult to sufficiently demonstrate the anti-fouling agent by adding an anti-fouling agent to the hard coating layer to provide anti-fouling properties, and when the amount of anti-fouling agent is increased to improve the anti-fouling property, the optical properties of the hard coating layer may deteriorate due to the added anti-fouling agent or the anti-fouling agent may deteriorate. There is a problem with bleed out. For this reason, an antifouling layer containing a fluorine-based compound is sometimes formed separately. However, as the number of layers constituting the cover window increases, the manufacturing process becomes more complex, which not only increases the production cost, but also increases the risk of deterioration of optical properties due to reflection or refraction at the interface between layers, and deterioration of durability due to delamination between layers. Therefore, the need for a hard coating layer that can satisfy various characteristics required for a cover window without forming a separate layer has been continuously raised.

Hard coating compositions using polymer resins such as acrylic polymers have high affinity for commonly used plastic materials, so they have excellent adhesion and advantages in flexibility and moldability, but they do not reach the level of hardness required for cover windows. . Inorganic materials such as silica particles have low flexibility and formability, but exhibit high hardness and transparency. Accordingly, a composition in which inorganic nanoparticles were dispersed in an acrylate composition was proposed to improve hardness. However, when physically dispersing inorganic nanoparticles, there is a problem in that dispersibility is reduced and optical properties are deteriorated due to agglomeration of the inorganic nanoparticles and refraction at the interface of the inorganic nanoparticles. Since hard coating requires properties such as flexibility, adhesion, and formability of organic materials and high hardness and transparency of inorganic materials, research and development is needed to develop an organic-inorganic hybrid composition that can realize these properties together. It is actively underway. However, a single hard coating layer alone is still not sufficient to satisfy the characteristics required for a cover window.

Registered Patent No. 10-2159687 Registered Patent No. 10-1664735 Registered Patent No. 10-1464550

In order to solve the problems of the prior art as described above, the present invention provides a hard coating composition that can form a hard coating film with excellent light transmittance, adhesion, and curved surface processability while exhibiting excellent hardness characteristics and antifouling properties with only a single hard coating layer. The purpose.

Another object of the present invention is to provide a hard coating film manufactured by curing the hard coating composition and a method for manufacturing the same.

Another object of the present invention is to provide a cover window for a display including the hard coating film.

Hereinafter, in describing the invention, if a detailed description of the known technology related to the invention is judged to unnecessarily obscure the gist of the invention, the detailed description will be omitted. In addition, in this specification, saying that a specific layer or membrane is 'on' another part includes not only being 'right on' the other part, but also cases where another layer or membrane is interposed between them. Additionally, in this specification, being placed ‘on’ may include being placed not only at the top but also at the bottom.

The present invention for achieving the above-described object includes a compound of the following formula (1); A compound of formula 2 below; and compounds of formula 3 below; It relates to a composition for hard coating, characterized in that it contains a siloxane resin composed of structural units derived from the present invention.

<Formula 1>

CH ₃ (CH ₂ ) ₈ CH ₂ Si(OR ¹ ) ₃

<Formula 2>

R ² Si(OR ³ ) ₃

<Formula 3>

Si(OR ⁴ ) ₄

In Formulas 1 to 3,

R ¹ , R ³ and R ⁴ are each independently a C1 to C4 linear or branched alkyl group,

R ² is a C1 to C4 linear, branched or alicyclic alkyl group with a substituted epoxy or acrylic group, a substituted or unsubstituted C6 to C12 aryl group, or a C1 to C4 linear or branched alkyl group with an alkene group. Hereinafter, in the description, the definitions of R ¹ , R ² , R ³ and R ⁴ are the same as those described above, unless otherwise specified.

Therefore, the siloxane resin constituting the hard coating composition of the present invention includes a T structural unit (I) derived from Chemical Formula 1, a T structural unit (II) derived from Chemical Formula 2, and a Q structural unit (III) derived from Chemical Formula 3, as follows. Includes.

The hard coating composition of the present invention is an organic-inorganic hybrid composition composed of an inorganic silane of the Q structural unit and an organic silane of the T structural unit. The hard coating film cured from the composition has excellent optical properties due to high hardness and anti-reflection function, It has both adhesion and moldability. In addition, as the alkyl chain of the decyl group (CH ₃ (CH ₂ ) ₈ CH ₂ -) of Formula 1 is introduced, antifouling properties and flexibility increase, and excellent surface strength and light transmittance can be maintained by mixing with other organosilanes. there is. On the other hand, the hard coating film formed from a composition containing a siloxane resin consisting only of the structural units of I and III showed antifouling properties, but the pencil hardness decreased rapidly according to the content of the structural units of I, resulting in excellent surface hardness and curved surface forming. It was difficult to form a hard coating film of consistent quality. The hard coating film formed from a composition containing a siloxane resin containing only structural units II and III had excellent hardness, but did not exhibit curved formability and antifouling properties. The hard coating composition of the present invention contains all structural units I, II, and III, so that the hard coating film cured thereof not only improves surface hardness, but also has excellent optical properties, curved formability, adhesion, and antifouling properties. It is characterized by Therefore, there is no need to separately form an anti-reflection layer to improve optical properties or an anti-fouling layer to show anti-fouling properties on the hard coating layer, thereby reducing material and process costs and reducing the weight of the product on which the hard coating film is formed. You can contribute.

As can be seen from the structural unit of the siloxane resin, R ¹ , R ³ and R ⁴ are not included in the siloxane resin and are removed during production of the siloxane resin, so they do not affect the properties of the hard coating film. Therefore, it can be combined with other organic silanes and/or inorganic silanes through hydrolysis and condensation reactions, and can be anything that can be removed in the drying/curing process for forming a hard coating film. R ¹ , R ³ and R ⁴ are each independently a C1 to C4 linear or branched alkyl group, but in addition, if they form a siloxane bond and do not affect the physical properties of the hard coating film due to remaining during the formation of the hard coating film, it is within the scope of the present invention. It can be said to be included in .

The structural unit of II is a structural unit that exhibits stable physical properties by suppressing rapid changes in hardness due to changes in the content of the structural unit of I. In the compound represented by Formula 2 forming the structural unit of II, R ² is a linear or branched alkyl group of C1 to C4 that additionally contains a polymerizable reactive group such as an epoxy group, an acrylic group, or an alkene group, or It is a substituted or unsubstituted aryl group of C6 to C12 that can exhibit high strength. Compounds of Formula 2 include 3-glycidoxypropyl trimethoxysilane, 3-glycidoxypropyl triethoxysilane, 3-glycidoxypropyl tripropoxysilane, 3-methacryloxypropyl trimethoxysilane, 3-methacryloxypropyl triethoxysilane, 3-acryloxypropyl trimethoxysilane, 3-acryloxypropyl triethoxysilane, 3-acryloxypropyl tripropoxysilane, 2-(3,4-epoxycyclo Hexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltripropoxysilane, phenyl trimethoxysilane, phenyl triethoxysilane Examples include, but are not limited to, ethoxysilane, phenyl tripropoxysilane, vinyl trimethoxysilane, vinyl triethoxysilane, or vinyl tripropoxysilane.

If the compound of Formula 2 has a photopolymerizable functional group such as an acrylic group or an alkene group, the composition may additionally include 0.1 to 3 wt% of a photoinitiator. If the amount of photoinitiator is too small, it is not efficient in initiating the photopolymerization reaction, and if the amount of photoinitiator is too large, it may affect the physical properties of the hard coating film.

In the composition of the present invention, the sum of the structural units of I and the structural units of II for the III structural unit I is preferably 0.1 to 0.5, and more preferably 0.2 to 0.35. If the sum of the structural units of I and II is too small, adhesion or curved surface formability cannot be obtained due to the introduction of organosilane, and if it is too large, it is difficult to achieve sufficient surface hardness or optical properties. In cases where curved surface molding is not required, the sum of the structural units of I and II, which are structural units derived from organosilane, can be reduced within the above range.

The ratio of structural units of I to structural units of II is preferably 1:2.5 to 2.5:1. If the ratio of structural unit I is too large, light transmittance may decrease and hardness may decrease. On the other hand, if the ratio of structural unit I is too small, the antifouling property decreases.

Another aspect of the present invention relates to a method for producing the hard coating composition.

The preparation method of the present invention includes the steps of (A) mixing a compound of Formula 1, a compound of Formula 2, and a compound of Formula 3 with a C1 to C4 alcohol to prepare a mixed solution; (B) performing a condensation reaction by adding water and an acid catalyst to the mixed solution; and (C) aging the condensation reaction solution.

The step (A) is a step of diluting the organosilane of Formula 1 and Formula 2 and the inorganic silane of Formula 3 with C1 to C4 alcohol. In this step, the C1 to C4 alcohols may be in a molar ratio of, for example, 8:1 to 12:1 with respect to the sum of the compounds of Formula 1, Formula 2, and Formula 3.

Silane containing an alkoxy group, such as the compound of Formula 1, the compound of Formula 2, and the compound of Formula 3, is formed through a condensation reaction using an acid as a catalyst through a two-step reaction of (1) hydrolysis reaction and (2) condensation polymerization reaction. It is well known to form siloxane resins. At this time, the acid accelerates the hydrolysis reaction by adjusting the pH, and is not limited to its type. In the following examples, nitric acid was used as the acid catalyst, but it is not limited to this, and any acid that can promote the condensation reaction, such as hydrochloric acid or sulfuric acid, can be used.

In step (B), the molar ratio of water to the sum of the compounds of Formula 1, Formula 2, and Formula 3 is preferably 1:1 to 1:5. If the molar ratio of water is too small, hydrolysis does not occur completely, and if the molar ratio of water is too large, the reaction rate becomes too slow. The reaction in this step is preferably performed at a temperature between room temperature and the boiling point of alcohol, and more preferably at a temperature between 40°C and the boiling point of alcohol.

The step (C) is a step in which the condensation reaction proceeds sufficiently to produce a transparent sol with a stable composition. The aging step is preferably performed at 0 to 20°C for more than 24 hours.

Another aspect of the present invention relates to a hard coating film formed on a substrate by curing the hard coating composition of the present invention. The substrate may be a glass or plastic substrate. The plastic substrate includes, for example, polycarbonate (PC), polymethylmethacrylate (PMMA), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyether sulfone. It may be based on polyethersulfone (PES), colorless polyimide (CPI), or cyclic olefin copolymer (COC).

As described above, the hard coating film produced by curing the hard coating composition of the present invention has a contact angle with water of 90° or more, showing antifouling properties. In addition, due to the anti-reflection property, the average light transmittance in the visible light region of the substrate on which the hard coating film of the present invention is formed is superior to the light transmittance of the substrate before the hard coating film is formed. The surface hardness of the hard coating film is affected by the substrate and thickness on which the hard coating film is formed. When the hard coating film with a thickness of 2 to 5 ㎛ is formed, the pencil hardness measured on the surface of the hard coating layer is 6H to 9H for the glass substrate and 4H to 7H for the PMMA substrate (2 mm thick), showing very excellent surface hardness. It was. As a result of performing curved molding on the hard coating film, it was confirmed that no cracks occurred even when the bending radius was less than 10 cm, showing excellent bending formability, and an adhesion test using a cross cut also showed very excellent adhesion.

The hard coating film of the present invention includes the steps of (A) coating the hard coating composition of claim 1 on a substrate; and (B) curing the applied composition. The applied composition may further include the step of (C) forming a curved surface after curing.

When curved molding is performed on a substrate on which a hard coating film is formed, it is more preferable to cure the hard coating composition in two steps. By dividing the process into primary and secondary curing, it is possible to prevent cracks during curved surface molding and form a hard coating film with higher surface hardness and excellent adhesion. For example, the primary curing and secondary curing can be controlled by thermal curing temperature. As illustrated in the examples below, after primary curing at 100°C to form a hard coating film with a surface strength of 4H, additional curing at 120°C increases the surface strength to 5H, so curved molding is performed after primary curing and additional curing is performed. It can be hardened. Alternatively, if the composition of claim 1 has a C1 to C4 linear or branched alkyl group substituted with a photopolymerizable acrylic group or has an alkene group, a photoinitiator is additionally included in the composition, and the secondary curing is carried out by photopolymerization by light irradiation. It can be done as much as possible.

Since the hard coating film of the present invention can exhibit excellent physical properties as a single coating film, it can be used to protect the surfaces of various items such as displays and home appliances. Accordingly, another aspect of the present invention relates to a cover window for a display including a substrate: and a hard coating film formed by curing the composition of claim 1. The cover window for a display to which the hard coating film of the present invention is applied is not limited to the type of the substrate, but in the case of a plastic substrate, it can be used more effectively because it can provide both high hardness and curved formability. In particular, its effectiveness can be proven in cases that require curved molding and release molding, such as next-generation automotive displays in which the entire front part is implemented as a central information display.

As described above, according to the hard coating composition of the present invention, it has both high hardness and curved formability due to the high hardness characteristics of inorganic silane and the flexibility of organic silane, and can be coated densely and uniformly without pinholes and has anti-reflection properties. It has the effect of improving light transmittance and has excellent anti-fouling and adhesion properties, so excellent properties can be given to the substrate with only a hard coating film of a single composition several microns thick without forming a separate anti-fouling layer or anti-reflection layer.

Therefore, the hard coating composition of the present invention can be usefully used to form a hard coating film on the surface of home appliances, including displays, and various articles. In particular, it can be more useful in fields that require curved or irregular molding, such as automotive displays, and that require anti-fouling and scratch resistance, as it can meet the performance with a single layer while maintaining other physical properties.

1 is a flow chart showing the manufacturing process of a hard coating composition according to an embodiment.
Figure 2 is a photograph of a composition for hard coating according to an example.
3A to 3E are images and graphs showing the characteristics of a glass substrate on which a hard coating film is formed according to an embodiment.
Figure 4 is an image and graph showing the characteristics of a plastic substrate on which a hard coating film is formed according to an embodiment.
Figures 5a to 5e are images showing contact angle characteristics of a plastic substrate on which a hard coating film is formed according to an example.
Figure 6 is a photograph of a composition for hard coating according to an embodiment of the present invention.
7A to 7C are images and graphs showing the characteristics of a substrate on which a hard coating film is formed according to an embodiment of the present invention.
Figure 8 is a graph showing an AFM image and coating film thickness of a hard coating film according to an embodiment of the present invention.
Figure 9 is an image showing the bending formability of a hard coating film according to an embodiment of the present invention.
Figure 10 is an image showing hardness characteristics according to heat treatment temperature of a hard coating film according to an embodiment of the present invention.
Figure 11 is an image showing the results of an adhesion test of a hard coating film according to an embodiment of the present invention.

The present invention will be described in more detail below with reference to the attached examples. However, these embodiments are only examples to easily explain the content and scope of the technical idea of the present invention, and the technical scope of the present invention is not limited or changed thereby. Based on these examples, it will be obvious to those skilled in the art that various modifications and changes are possible within the scope of the technical idea of the present invention.

[Example]

Example 1: Organic-inorganic hybrid hard coating using a single organosilane

1) Preparation of composition for hard coating

An organic-inorganic hybrid hard coating composition was prepared by reaction of metal alkoxide and organosilane.

TEOS (tetraethyl orthosilicate) was used as a metal alkoxide, and as organosilanes, PTMS (Trimethoxyphenylsilane), GPTMS (3-Glycidyloxypropyl)trimethoxysilane), VTMS (Vinyltrimethoxysilane), TMSPM (3-(Trimethoxysilyl)propyl methacrylate, and DTMS (Decyltrimethoxysilane) was used.

More specifically, a solution was prepared by mixing one of the above organosilanes at a molar ratio of 0.1, 0.25, 0.5, 0.75, or 1.0 based on 1 mole of TEOS and diluting it with 9.31 mole of ethanol. A dilute aqueous nitric acid solution was prepared by mixing 3.62 moles of DI water with 0.08 moles of nitric acid (60%), which was added dropwise to the ethanol solution. Once the dropwise addition was completed, the reaction was maintained at 50-60°C for 5 hours and stirred at room temperature for an additional 24 hours. The prepared composition was stored in refrigeration, aged for more than 1 day, and then used as a coating solution. Figure 1 shows the manufacturing process of the composition of this example.

Figure 2 is a photograph of the hard coating composition prepared using each organosilane, and it can be seen that a transparent sol was formed in all of them.

2) Manufacturing of hard coating film

A hard coating film was prepared on a glass substrate, PC or PMMA substrate by dip coating using the hard coating composition prepared in 1) above. The thickness of each substrate was 2 mm. The dip coating pulling speed was set at 2 mm/s, and the substrate was immersed in the solution, pulled up, maintained at room temperature for 10 minutes, and the coating solution was first dried in air. 10 to 30 minutes after the coating liquid loses its fluidity The coating film was secondarily dried by keeping it in an oven at 100°C for 0.5 hours.

3) Evaluation of the characteristics of the substrate on which the hard coating film is formed

The average light transmittance, pencil hardness, and contact angle with water in the visible light region were measured for each of the hard coating films prepared on the glass substrate in 2), and the results are shown in Tables 1 to 3 and Figures 3a to 3e below. Samples HX-1, 2, 3, 4, and 5 described in light transmittance in a to e of Figure 3 are samples in which the mole percent of alkylsilane relative to the number of moles of TEOS in each sample is 0.1, 0.25, 0.5, 0.75, and 1.0. it means. Light transmittance was measured using a UV-VIS-NIR spectrometer, pencil hardness was measured using a pencil hardness tester, and contact angle was measured using a contact angle measurement.

From the results in Table 1, the average visible light transmittance of the glass substrate without a hard coating film was 91.2%, and most of the hard coating films (indicated by shading) in Table 1 showed the same or improved transmittance as the glass substrate. This can be interpreted as the fact that the refractive index of the hard coating film is lower than that of the glass substrate, thereby demonstrating the anti-reflection effect. However, in the case of PTMS, when the molar concentration exceeded 0.5% compared to TEOS, the coating film was not completely cured even after being kept in an oven at 100°C for 0.5 hours, making property evaluation impossible. In particular, GPTMS, VTMS, and DTMS showed very high transmittance of over 93% at a certain content.

Table 2 shows that pencil hardness decreases as the concentration of alkylsilane in the composition increases. This is believed to be because flexibility increases as the proportion of organic groups in the composition increases. Among organosilanes, VTMS has the best pencil hardness, showing that it can be useful in fields that do not require flexibility. When DDTMS was contained at 0.1%, it showed excellent pencil hardness, but when the content increased to 0.25%, pencil hardness rapidly decreased.

The contact angle in Table 3, unlike pencil hardness, tended to increase as the concentration of alkylsilane increased. In particular, DTMS showed excellent antifouling properties with a contact angle of around 100°, which is a similar value to fluorine-based silanes commonly used as antifouling agents. Therefore, it can be usefully used as a replacement for fluorine-based silane for antifouling effect. Although TPSPM was not as good as DTMS, it showed excellent antifouling properties.

Light transmittance, pencil hardness, and contact angle were also measured for the hard coating film formed on PC or PMMA as a plastic material, and the results are shown in Tables 4 to 6 and Figures 4 and 5a to 5e.

As can be seen in Table 5, the PC and PMMA substrates containing the hard coating film of this example both showed transmittances of 90% or more, and in most cases, showed higher transmittances than glass substrates on which no coating layer was formed.

Before forming the hard coating film, the pencil hardness of the PC substrate is 4B, and the pencil hardness of PMMA is 2H. As the hard coating layer was formed on the PC substrate, the pencil hardness increased to HB, and the PMMA substrate also showed an improvement in pencil hardness to 3H~6H. The composition containing VTMS formed a hard coating film with high hardness characteristics on the PMMA substrate as well as on the glass substrate.

The surface contact angle of the PC substrate before forming the hard coating film is 72.5°, and the surface contact angle of PMMA is 64.9°. When a hard coating film using GPTMS, VTMS, and TMSPM was formed on a PC substrate, the surface contact angle was lowered, and PTMS had little effect on the surface contact angle. A similar trend was observed in the case of the PMMA substrate, but the hard coating film using PTMS showed an effect of improving the contact angle compared to the PC substrate. On the other hand, DTMS had a significant effect of improving the contact angle, similar to the glass substrate, showing the possibility that the hard coating layer could also serve as an antifouling layer.

Example 2: Organic-inorganic hybrid hard coating using organosilane mixture

1) Preparation of hard coating composition and hard coating film

A hard coating composition was prepared in the same manner as Example 1 1), except that instead of using a single organosilane as the organosilane, two organosilanes were mixed according to the composition shown in Table 7 below. The two organosilanes were mixed at 0.1 mol + 0.1 mol, 0.1 mol + 0.25 mol, or 0.25 mol + 0.1 mol based on 1 mol of TEOS to prepare a composition. Figure 6 is a photograph of the compositions prepared according to one example, and it can be seen that all of them form a transparent sol.

A hard coating film was prepared in the same manner as 2) of Example 1 using each of the prepared compositions. To reduce the influence of the substrate, a coating film was manufactured using a glass substrate.

2) Evaluation of the characteristics of the substrate on which the hard coating film is formed

The properties of the substrate on which the hard coating film was formed in 1) were evaluated by the same method as 3) of Example 1, and the results are shown in Tables 7 to 9 and Figures 7a to 7c. In Tables 7 to 9, 0.1 + 0.1 means that two alkylsilanes are mixed at a ratio of 0.1 mol + 0.1 mol for 1 mol of TEOS, and the sample number of this sample is indicated as NO-1 in the drawings below. For example, if the sample is marked as D3-2, this means that it is a composition prepared by mixing 0.1 mole of PTMS and 0.25 mole of DTMS with respect to 1 mole of TEOS.

Organosilanes manufactured using two types of organosilanes together with TEOS showed light transmittances of over 90% except for the D8-2 sample, and in most cases, light transmittances increased compared to the glass substrate itself, acting as an anti-reflection film. showed that

In the test results for pencil hardness, when DTMS was used alone, the hard coating film made with 0.25 mol% DTMS had a very low pencil hardness of 1H, but when two organosilanes were mixed and used, DTMS was used at 0.25 mol%. Even when it was included, it showed high hardness of 6H or higher except for the sample D10-3, and when mixed with PTMS, the pencil hardness reached 9H even when 0.25 mol% of DTMS was used.

The contact angle results in Table 9 showed that all hard coating films manufactured including DTMS had contact angles of 90° or more, showing that they had antifouling properties. In all cases without DTMS, the contact angle was too small to exhibit antifouling properties.

The above results show that the hard coating film manufactured using a hard coating composition prepared by mixing DTMS and an organosilane other than DTMS with TEOS significantly increases hardness as a single film without forming a separate anti-reflective film or antifouling layer. In addition to improving the light transmittance through the anti-reflection effect, it shows that it has anti-fouling properties.

Figure 8 is an AFM image of sample D6-1, showing that the RMS surface roughness is very low at about 2.585 nm and that a coating film with a thickness of 3.245 ㎛ is uniformly formed. The reason why the coating films of this example exhibit high light transmittance is because they were coated densely and uniformly without cracks or pinholes even though they were formed at a micro thickness.

A hard coating film was prepared using the composition D6-3 on a 21 cm × 30 cm × 2 mm PMMA substrate, and the surface processability was evaluated. Specifically, the composition D6-3 was applied on a PMMA substrate, and then a coating film was prepared using Bar coating. The bar used at this time was #20 or #30, considering the thickness of the final coating film. The bar was coated with a moving speed of 5 to 10 mm/s. After coating, the first coating film was maintained at room temperature for about 10 minutes and then dried in an oven at 100°C for 1 hour. To perform curved molding, the substrate was placed on a carbon mold with a bending radius of 5 cm, kept at 120°C for 1 hour, and then lightly pressed with the upper plate to form it. For comparison, the same experiment was conducted by manufacturing a hard coating film using a composition prepared by mixing only 0.25 mol% of GPTMS with respect to 1 mole of TEOS without containing DTMS.

Figure 9 is a photograph showing the results. Although the substrate on which the hard coating film was formed using the composition prepared from TEOS and GPTMS cracked after hard coating, the substrate on which the hard coating film was formed with the composition of D6-3 did not crack or develop a hard coating film. It was confirmed that curved surface forming was possible without peeling.

Figure 10 shows the results of evaluating hardness characteristics and adhesion according to heat treatment temperature after forming a hard coating film using bar coating on a 2 mm thick PMMA substrate using the composition of D6-3. The pencil hardness after initially curing the hard coating composition at 100°C for 1 hour was 4H, and when it was further cured at 120°C for 1 hour, the pencil hardness increased to 5H.

Figure 11 is a diagram showing the results of an adhesion test according to ASTM D3359 for a sample cured for an additional 1 hour at 120°C. It can be seen that the coating on all edges is adhered cleanly (Class 5B), showing excellent adhesion.

Claims (22)

A compound of formula 1 below;
A compound of formula 2 below; and
A compound of formula 3 below;
A composition for hard coating, characterized in that it contains a siloxane resin composed of derived structural units.
<Formula 1>
CH ₃ (CH ₂ ) ₈ CH ₂ Si(OR ¹ ) ₃
<Formula 2>
R ² Si(OR ³ ) ₃
<Formula 3>
Si(OR ⁴ ) ₄
In Formulas 1 to 3,
R ¹ , R ³ and R ⁴ are each independently a C1 to C4 linear or branched alkyl group,
R ² is a C1 to C4 linear, branched or alicyclic alkyl group with a substituted epoxy or acrylic group, a C1 to C4 linear or branched alkyl group with an alkene group, or a substituted or unsubstituted C6 to C12 aryl group.
In claim 1,
A composition for hard coating, characterized in that the sum of the structural units derived from the compound of Chemical Formula 1 and the compound of Chemical Formula 2 is 0.1 to 0.5, relative to the structural unit 1 derived from the compound of Chemical Formula 3.
In claim 2,
A composition for hard coating, characterized in that the ratio of the structural unit derived from the compound of Chemical Formula 1 to the structural unit derived from the compound of Chemical Formula 2 is 1:2.5 to 2.5:1.
In claim 1,
A composition for hard coating, characterized in that it further comprises 0.1 to 3 wt% or less of a photoinitiator in the composition.
The method according to any one of claims 1 to 4,
The compound represented by Formula 2 is 3-glycidoxypropyl trimethoxysilane, 3-glycidoxypropyl triethoxysilane, 3-glycidoxypropyl tripropoxysilane, 3-methacryloxypropyl trimethoxy Silane, 3-methacryloxypropyl triethoxysilane, 3-acryloxypropyl trimethoxysilane, 3-acryloxypropyl triethoxysilane, 3-acryloxypropyl tripropoxysilane, 2-(3,4- Epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltripropoxysilane, phenyl trimethoxysilane, A composition for hard coating, characterized in that it is at least one selected from phenyl triethoxysilane, phenyl tripropoxysilane, vinyl trimethoxysilane, vinyl triethoxysilane, and vinyl tripropoxy silane.
(A) preparing a mixed solution by mixing a compound of Formula 1, a compound of Formula 2, and a compound of Formula 3 below with a C1 to C4 alcohol;
(B) performing a condensation reaction by adding water and an acid catalyst to the mixed solution; and
(C) aging the condensation reaction liquid;
A method for producing the hard coating composition of claim 1 comprising.
<Formula 1>
CH ₃ (CH ₂ ) ₈ CH ₂ Si(OR ¹ ) ₃
<Formula 2>
R ² Si(OR ³ ) ₃
<Formula 3>
Si(OR ⁴ ) ₄
In Formulas 1 to 3,
R ¹ , R ³ and R ⁴ are each independently a C1 to C4 linear or branched alkyl group,
R ² is a C1 to C4 linear, branched or alicyclic alkyl group with a substituted epoxy or acrylic group, a substituted or unsubstituted C6 to C12 aryl group, or a C1 to C4 linear or branched alkyl group with an alkene group.
In claim 6,
A manufacturing method characterized in that the molar ratio of water used in step (B) to the sum of the compounds of Formula 1, Formula 2, and Formula 3 used in step (A) is 1:1 to 1:5.
In claim 6,
A manufacturing method characterized in that step (C) is performed at 0 to 20°C for more than 24 hours.
A hard coating film formed on a substrate by curing the composition of claim 1.
In claim 9,
A hard coating film, characterized in that the substrate is a glass or plastic substrate.
In claim 9,
The hard coating film is characterized in that the contact angle with water is 90° or more.
In claim 9,
A hard coating film, characterized in that the average light transmittance in the visible light region of the substrate on which the hard coating film is formed is higher than the light transmittance of the substrate before the hard coating film is formed.
In claim 9,
When the substrate is a glass substrate, a hard coating film characterized in that the pencil hardness measured on the surface side of the hard coating film with a thickness of 2 to 5 ㎛ is 6H to 9H.
In claim 9,
When the substrate is a PMMA substrate, the hard coating film is characterized in that the pencil hardness of the substrate on which the hard coating film is formed is 4H to 7H.
In claim 9,
A hard coating film, characterized in that the bending radius of the hard coating film is 10 cm or less.
(A) coating the hard coating composition of claim 1 on a substrate; and
(B) curing the applied composition;
A method for manufacturing a hard coating film comprising:
In claim 16,
After step (B) above,
(C) curved forming the substrate on which the hard coating film is formed;
A method of manufacturing a hard coating film, characterized in that it further comprises.
In claim 17,
After step (C) above,
(D) secondary curing of the curved molded hard coating film;
A method of manufacturing a hard coating film, characterized in that it further comprises.
In claim 18,
The composition of claim 1 is
In the compound of Formula 2, R ² is a C1 to C4 linear or branched alkyl group substituted with an acrylic group, or a C1 to C4 linear or branched alkyl group having an alkene group,
The composition further includes a photoinitiator,
The step (D) is a method of manufacturing a hard coating film, characterized in that it is further cured by light irradiation.
Substrate: and
A hard coating film formed by curing the composition of claim 1;
A cover window for a display including.
In claim 20,
A cover window for a display, characterized in that the substrate is a plastic substrate.
In claim 20 or claim 21,
A cover window for a display, characterized in that the display is a display for an automobile.