KR20150140114A - Scratch-resistant hard-coating composition consisting of combined multi-functional acrylic monomers and hard-coating using the same - Google Patents

Abstract

An intrinsic scratch resistant hard coating composition according to one embodiment of the present invention comprises at least two multi-functional acrylic monomer mixtures; A bifunctional acrylate having a molecular weight of 7,000 to 20,000; Organic solvent; And additives. In addition, a scratch resistant hard coating according to another embodiment of the present invention is formed by coating a hard coating composition comprising at least two polyfunctional acrylic monomer mixtures, a bifunctional acrylate having a molecular weight of 7,000 to 20,000, an organic solvent and an additive, And then curing by irradiation with ultraviolet rays.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scratch resistant hard coating composition composed of a polyfunctional acrylic monomer and a hard coating using the scratch resistant composition. 2. The hard scratch resistant hard coating composition according to claim 1,

The present invention relates to a hard coating composition for coating polycarbonate which is a transparent polymer sheet, and a hard coating using the same.

In recent years, the key keyword in the automotive sector is improving fuel efficiency by reducing weight. In order to achieve lighter weight, parts based on polymer resin instead of heavy and heavy metal or ceramic materials are steadily emerging. Polymer composites and transparent polymer windows used for automotive interior and exterior parts and engine parts are typical examples.

Polycarbonate (PC) has excellent transparency, mechanical strength, and heat resistance, and is widely used for manufacturing transparent sheets for construction. It is expected that demand for parts for automobile windows will increase greatly. Its specific gravity is about 1.2 g / ㎤, which is more than 1/2 lighter than glass, and its refractive index is about 1.585. In addition, since it has an impact resistance of about 250 times or more than that of plate glass, it is effective for prevention of detachment of passengers in collision and overturning, which is excellent in safety and hard to break from outside. (Tm) of 220 to 250 ° C, a glass transition temperature (Tg) of 145 ° C, and a heat distortion temperature (HDT) of 120 to 140 ° C. Polycarbonate has attracted much attention as a substitute material for glass due to its advantages such as high visible light transmittance (85% or more), impact resistance, weatherability and self-extinguishing ability. However, due to the ductility characteristics, the scratch resistance is low and the adhesion to the coating layer is poor, which limits the application field. Therefore, it is necessary to develop a coating system having improved adhesion to the substrate while improving the scratch resistance with the substrate.

The embodiments of the present invention are designed to solve the problems of the prior art as described above, and include at least two kinds of multi-functional acrylic monomer mixture; A bifunctional acrylate having a molecular weight of 7,000 to 20,000; Organic solvent; And an additive, and to provide an intrinsic scratch resistant hard coating obtained by coating and drying the intrinsic scratch resistant hard coating composition, followed by curing by irradiating ultraviolet ray, and a method of manufacturing the same It is a technical task.

An intrinsic scratch resistant hard coating composition according to one embodiment of the present invention comprises at least two multi-functional acrylic monomer mixtures; A bifunctional acrylate having a molecular weight of 7,000 to 20,000; Organic solvent; And additives.

The polyfunctional acrylic monomer mixture may contain at least two acrylic monomers selected from the group consisting of a 15-functional acryl monomer, a 10-functional acrylic monomer and a 6-functional acrylic monomer, and may contain 10% by weight to 40% 10 to 30% by weight of a 10-functional acrylic monomer, and 5 to 10% by weight of a 6-functional acrylic monomer.

The organic solvent may be Ethyl Acetate (EA).

The additive may be a photoinitiator.

A method of forming an inner scratch resistant hard coating according to another embodiment of the present invention comprises preparing a hard coating composition comprising at least two or more polyfunctional acrylic monomer mixtures, a bifunctional acrylate having a molecular weight of 7,000 to 20,000, an organic solvent and an additive ; Coating the hard coating composition on at least one side of the substrate; Drying the hard coating composition at a temperature of from 60 DEG C to 100 DEG C for 1 minute to 10 minutes; And ultraviolet light having a total light quantity of 1000 mJ / cm 2 to 2000 mJ / cm 2 for 3 seconds to 30 seconds.

A scratch resistant hard coating according to another embodiment of the present invention is prepared by coating a hard coating composition comprising at least two or more polyfunctional acrylic monomer mixtures, a bifunctional acrylate having a molecular weight of 7,000 to 20,000, an organic solvent and an additive, , And irradiating ultraviolet rays to cure.

The hard scratch resistant hard coating after curing may have a pencil hardness H or higher and a visible light transmittance of 85% or higher.

The embodiment of the present invention is designed to solve the problems inherent in polycarbonate and has an effect of simultaneously improving the scratch resistance and adhesion by controlling the network density through the combination of urethane-based acrylic monomers having different functional groups have. Also, the hard coat composition suitable for a large-area coating process can be prepared by controlling the flowability of the coating liquid according to the composition ratio of the acrylic monomer and the solid fraction.

1 is a process flow diagram of a method of making a scratch resistant hard coating in accordance with an embodiment of the present invention.
2 is a conceptual diagram schematically illustrating a method of manufacturing a scratch resistant hard coating according to an embodiment of the present invention.
Fig. 3 is a photograph of contact angles measured in Examples and Comparative Examples of the present invention.
4 is a scanning electron microscope (SEM) photograph of a scratch resistant hard coating according to an embodiment of the present invention.
5 is a photograph showing the results of the adhesion tests of Examples and Comparative Examples of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood, however, that the embodiments described in the present specification and the constitutions shown in the drawings are only a preferred embodiment of the present invention, and that various equivalents and modifications can be made at the time of filing of the present application . DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the subject matter of the present invention. The following terms are defined in consideration of the functions of the present invention, and the meaning of each term should be interpreted based on the contents throughout this specification. The same reference numerals are used for portions having similar functions and functions throughout the drawings.

An intrinsic scratch resistant hard coating composition according to one embodiment of the present invention comprises at least two multi-functional acrylic monomer mixtures; A bifunctional acrylate having a molecular weight of 7,000 to 20,000; Organic solvent; And additives.

The polyfunctional acrylic monomer mixture is a mixture of urethane-based acrylic monomers and may include a 15-functional acrylic monomer, a 10-functional acrylic monomer, a 6-functional acrylic monomer or a mixture thereof. The hard coating composition comprising the urethane-based acrylic monomer mixture is advantageous in terms of controlling final properties of the coating layer since the curing rate upon irradiation with ultraviolet rays is fast and the curing condition, that is, light quantity, temperature and irradiation time can be easily controlled. The reason for mixing at least two kinds of the multi-functional acrylic monomer mixture is that the scratch characteristics of the coating layer can be controlled by controlling the density of the network. 10 to 40% by weight of the 15-functional acrylic monomer, 10 to 30% by weight of the 10-functional acrylic monomer, and 5 to 10% by weight of the 6-functional acrylic monomer.

The high molecular weight bifunctional acrylate may be included in the scratch resistant heart coating composition according to one embodiment of the present invention to improve the flexibility and hardness of the hard coating composition. As the bifunctional acrylate, those having a large molecular weight can be used. The above-mentioned diatomic acrylate preferably has a molecular weight of 7,000 to 20,000, more preferably 10,000 to 15,000. The bifunctional acrylate may be included in the total composition in an amount of 5% by weight to 15% by weight.

Ethyl acetate (EA) may be used as the organic solvent. The organic solvent may be contained in an amount of 30% by weight to 85% by weight of the whole composition. Since ethyl acetate has a low boiling point (BP, ~ 77 ° C), the hard coating composition can be easily removed even in a general oven when it is dried. Also, if the contact time with the substrate to be coated is short, an interpentration layer can be formed by etching the surface without affecting transparency. The increase of the surface roughness of the coated substrate due to etching increases the contact area with the coating layer and consequently leads to the improvement of the adhesion.

As the additive, a photoinitiator may be used. The photoinitiator may be included in the total composition in an amount of 1 wt% to 5 wt%. In the step of irradiating ultraviolet rays after coating the hard coating composition according to an embodiment of the present invention, the photoinitiator is decomposed to form radicals. The photoinitiator may be a conventionally known photoinitiator. As the photoinitiator, commercially available Irgacure 184, Irgacure 754, Irgacure 1173, Irgacure 651 and the like can be used.

FIG. 1 is a process flow diagram of a method of manufacturing an inner scratch resistant hard coating according to an embodiment of the present invention, and FIG. 2 is a conceptual diagram schematically illustrating a method of manufacturing an inner scratch resistant hard coating according to an embodiment of the present invention to be.

Referring to FIGS. 1 and 2, a method for forming an inner scratch resistant hard coating according to another embodiment of the present invention includes at least two kinds of polyfunctional acrylic monomer mixture, acrylate having a molecular weight of 7,000 to 20,000, an organic solvent and an additive Preparing a hard coating composition comprising (SlOO); Coating the hard coating composition on at least one side of the substrate (S200); Drying the hard coating composition at a temperature of 60 ° C to 100 ° C for 1 minute to 10 minutes (S300); And irradiating ultraviolet light having a total light amount of 500 mJ / cm2 to 2000 mJ / cm2 for 3 seconds to 30 seconds (S400).

In step S100 of preparing the hard coating composition 120, the hard coating composition is prepared according to the above-described composition. The components and composition of the hard coating composition 120 have been described above, and therefore, a description thereof will be omitted in order to avoid redundancy. First, the 15-functional acrylic monomer, the 10-functional acrylic monomer, and the 6-functional acrylic monomer are completely dissolved in the organic solvent. When the polyfunctional acrylic monomer mixture is completely dissolved, the acrylate is added and mixed. The hard coating composition 120 is then homogenized by stirring for at least 2 hours.

In the coating step (S200), the homogenized hard coating composition (120) is coated on the polycarbonate (110) using a bar coater or a spin coater. The coating method is not limited in this embodiment, and a coating method which is usually used in a similar process can be used. The thickness of the layer to be coated can be adjusted according to the required physical properties, so that the drying time, the total amount of light upon irradiation with ultraviolet rays and the irradiation time can be controlled in a subsequent process.

In the drying step S300, the polycarbonate 110 coated with the hard coating composition 120 is dried in an oven maintained at a temperature of 60 ° C to 100 ° C for 1 minute to 10 minutes. The drying time is adjustable according to the thickness of the coating, and it is preferable to leave the oven for a sufficient time for the organic solvent to be completely removed. The hard coating composition 120 thus removes the organic solvent and leaves only the mixture of monomers 120 'on the polycarbonate 110. The apparatus used in the drying step S300 may be one used in a general process such as a convection oven, but is not limited thereto. In the drying step S300, the surface of the polycarbonate 110 is etched while the organic solvent is completely removed to form the unevenness 112. The unevenness 112 increases the roughness of the surface of the polycarbonate 110 to increase the contact area with the coating layer.

In the ultraviolet irradiation step (S400), the hard coating layer is irradiated with ultraviolet rays (UV) so that the monomer mixture may cause a photo-curing reaction. A mercury lamp or the like can be used for the ultraviolet ray irradiation, and the ultraviolet ray intensity is not particularly limited as long as the intensity of the ultraviolet ray is 200 mW / cm 2 to 300 mW / cm 2. In this embodiment, an ultraviolet curing conveyor system incorporating a mercury lamp is used. The UV curing conveyor system with the mercury lamp can control the curing rate and network density by controlling the speed of the continuously moving conveyor to control the total amount of exposure the specimen is exposed to. When ultraviolet light (UV) is irradiated, the mixture of monomers 120 'is polymerized to form network 122. The polymer 120 ' on which the network 122 is formed enhances the hardness of the surface.

A scratch resistant hard coating according to another embodiment of the present invention is prepared by coating and drying a hard coating composition comprising at least two kinds of polyfunctional acrylic monomer mixture, acrylate having a molecular weight of 7,000 to 20,000, an organic solvent and an additive, And then curing. The hard scratch resistant hard coating after curing may have a pencil hardness H or higher and a visible light transmittance of 85% or higher.

The components and the composition of the above scratch resistant hard coating composition and the method of producing the hard coating have been described above, so that the description thereof will be omitted in order to avoid duplication.

Hereinafter, the present invention will be described more specifically by way of examples. However, the following examples are intended to aid understanding of the present invention, and the scope of the present invention is not limited to these examples in any sense.

[ Example ]

Example  1 to Example  6

A monomer mixture composed of 46% by weight of a 15-functional acryl monomer, 34% by weight of a 10-functional acrylic monomer and 8% by weight of a 6-functional acrylic monomer, 12% by weight of an acrylate having a molecular weight of 7,000 to 20,000 and 3% by weight of a photoinitiator were dissolved in an excess amount of ethyl acetate . The composition was then homogenized by stirring for 2 hours and then coated on a polycarbonate film using a bar coater.

The coated specimens were placed in an oven maintained at 70 ° C and dried for 3 minutes to 5 minutes depending on their thickness, after which the ethyl acetate was completely removed and cured by irradiating ultraviolet rays.

The thickness of the coating layer and the total light amount of irradiated ultraviolet rays are shown in Table 1.

Example 1 Thickness (㎛)
(Total ultraviolet light: 1,200 mJ / cm 2) 20 Example 2 30 Example 3 40 Example 4 Total light amount (mJ / cm 2)
(Coating layer thickness: 30 占 퐉) 750 Example 5 1300 Example 6 2000

[evaluation]

1. Pencil Hardness

Changes in pencil hardness and transmittance according to the thickness of the coating layer cured with ultraviolet rays and the total exposure light amount of UV were measured and are shown in Table 2 below. The changes in hardness with the thickness of the coating layer were 20 ㎛, 30 ㎛ and 40 ㎛, respectively, and the pencil hardness increased with H, 2H, and 3H, respectively. As the thickness of the coating layer increases, the effect of the polycarbonate substrate of soft properties is reduced and it is considered that the hardness is improved.

When the thickness of the coating layer is adjusted to about 30 탆, the change in hardness according to the total amount of ultraviolet light shows a 2H at 700 mJ / cm 2 or more, so that a similar network can be expected. This means that the coating solution can be sufficiently cured even at a low light amount and can be energy-reduced when a large-scale coating is performed for commercialization.

2. Transmittance

The transmittance of the visible light was measured using a light transmittance meter (NDH2000, Nippon Denshoku) after being coated on a rectangular polycarbonate having a width of 10 cm and a length of 5 cm. The visible light transmittance of the specimen after coating was more than 85% regardless of the thickness of the coating layer and the ultraviolet ray intensity, showing no significant difference from the uncoated polycarbonate.

3. Color Cart

Light transmittance The specimens were placed in a colorimeter (CM-5, Konica Minolta) and the colorimeter was measured and shown in Table 2 below.

a is the plane coordinate value of the colorimeter with a vertical axis b and the + a side is red, the -a side is green, the + b side is yellow, and the -b side is blue. It means that it is converted. It can be seen that the color coordinate of the coated polycarbonate is less than 1 in most specimens and there is little color change.

Pencil hardness Visible light transmittance (%) a * b * Example 1 H 85 -0.55 0.81 Example 2 2H 86 -0.51 0.9 Example 3 3H 85 -0.56 0.86 Example 4 2H 87 -0.55 0.72 Example 5 2H 85 -0.51 0.9 Example 6 2H 85 -0.69 1.15

4. Contact angle

The contact angle of the polycarbonate before and after coating was measured and shown in Fig.

The contact angles of the polycarbonate before coating (FIG. 3 a) were 75.18 ° (left) and 74.99 ° (right), and the contact angles after coating (FIG. 3b) were 73.85 ° (left) and 76.39 ° Surface properties.

5. Sectional SEM

In order to examine the structure at the interface between the coating layer and the substrate, the coated polycarbonate specimen was immersed in liquid nitrogen and cut vertically, and the cross section was observed using a scanning electron microscope (SEM) Fold, and (b) at 30000 magnification). The polycarbonate layer and the coating layer are clearly distinguished and the coated surface is flat and uniform. The thickness of the portion indicated by the arrow in the left SEM photograph is 3592.80 nm.

6. Adhesion

FIG. 5 shows a result of the adhesion test according to ASTM D3359 to confirm the adhesion of the coating layer. A checkerboard groove was formed on the coated specimen with a cutter at intervals of 1 mm, and the transparent cellophane tape was closely adhered to the coated specimen and peeled off several times with a constant force to confirm the adhesion between the coating layer and the substrate. 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 than 0B. As a result of the adhesion test, it was confirmed that the coating layer was retained on the polycarbonate surface, and the adhesion strength of 5B was shown.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. The scope of the present invention should be interpreted based on the scope of the following claims, and all technical ideas within the scope of equivalents thereof should be interpreted in accordance with the following claims: It is to be understood that the invention is not limited thereto.

110: Polycarbonate film
120: hard coating composition
UV: ultraviolet

Claims (12)

At least two or more polyfunctional acrylic monomer mixture;
A bifunctional acrylate having a molecular weight of 7,000 to 20,000;
Organic solvent; And
additive;
≪ / RTI >
The method according to claim 1,
The multifunctional acrylic monomer mixture may contain,
Wherein the acrylic copolymer comprises at least two acrylic monomers selected from the group consisting of an acrylic monomer, an acrylic monomer, a 15-functional acrylic monomer, a 10-functional acrylic monomer and a 6-functional acrylic monomer.
The method according to claim 1 or 2,
The multifunctional acrylic monomer mixture may contain,
Wherein the hard coat composition comprises 20 to 50% by weight of a 15-functional acrylic monomer, 20 to 40% by weight of a 10-functional acryl monomer, and 5 to 10% by weight of a 6-functional acrylic monomer.
The method according to claim 1,
The organic solvent may include,
Ethyl acetate (EA). ≪ RTI ID = 0.0 > 8. < / RTI >
The method according to claim 1,
Preferably,
Wherein the hard coat composition is a photoinitiator.
The method according to claim 1,
The monomer may be,
And 15 to 70% by weight as a solid content.
Preparing a hard coat composition comprising at least two or more polyfunctional acrylic monomer mixture, acrylate having a molecular weight of 7,000 to 20,000, an organic solvent and an additive;
Coating the hard coating composition on at least one side of the substrate;
Drying the hard coating composition at a temperature of from 60 DEG C to 100 DEG C for 1 minute to 10 minutes; And
Irradiating ultraviolet light having a total light amount of 500 mJ / cm 2 to 2000 mJ / cm 2 for 3 seconds to 30 seconds;
≪ / RTI > wherein the hard coat layer comprises a hard coat.
The method of claim 7,
The multifunctional acrylic monomer mixture may contain,
Characterized in that it comprises 20% by weight to 50% by weight of a 15-functional acryl monomer, 20% by weight to 40% by weight of a 10-functional group acrylic monomer and 5% by weight to 10% by weight of a 6-functional acrylic monomer. .
An intrinsic scratch resistant hard coating obtained by coating a hard coating composition comprising at least two or more polyfunctional acrylic monomer mixtures, an acrylate having a molecular weight of 7,000 to 20,000, an organic solvent and an additive, drying and then curing by irradiation with ultraviolet light.
The method of claim 9,
The multifunctional acrylic monomer mixture may contain,
Wherein the hard coat layer comprises 20% by weight to 50% by weight of a 15-functional acryl monomer, 20% by weight to 40% by weight of a 10-functional acryl monomer, and 5% by weight to 10% by weight of a 6-functional acrylic monomer.
The method of claim 9,
The hard scratch-resistant hard coating, after curing,
Pencil hardness H or higher.
The method of claim 9,
The hard scratch-resistant hard coating, after curing,
And a visible light transmittance of 85% or more.

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