WO2018012800A1 - Hard coating composition having improved abrasion resistance after curing, and molded film comprising same - Google Patents

Abstract

The present invention relates to: a hard coating composition, which has improved abrasion resistance after curing, by containing a surface type additive which comprises a polysiloxane compound and having a rheology index of 1.0-1.2 determined by the following formula 1; and a molded film comprising a substrate layer and a hard coating layer formed on the substrate layer, wherein the hard coating layer is formed from a hard coating composition containing a surface type additive which comprises a polysiloxane compound and having a rheology index of 1.0-1.2 determined by the following formula 1. [Formula 1] Rheology index = (viscosity at low shear rate)/(viscosity at high shear rate)

Description

Hard coating composition having improved abrasion resistance after curing and molded film comprising the same

The present invention relates to a hard coating composition and a molded film comprising the same.

By hard coating layer is meant a protective layer formed on the device to protect the particular device. The hardcoat layer also serves to protect the device from acids, chemicals such as bases or rays such as ultraviolet light, but the primary function of the hardcoat layer is to protect the device from external shocks, ie scratches. In order to protect the device from impacts from the outside, the hardcoat layer must be highly wear resistant. In order to improve the wear resistance of the hard coating layer, the hard coating composition includes hard particles. The content of hard particles in the hard coating composition and the wear resistance of the hard coating layer generally have a positive correlation, but it is not possible to continue to increase the hard particle content to improve the wear resistance of the hard coating layer. This is because the higher the hard particle content in the hard coating composition, the lower the flexibility of the hard coating layer. Low-flexibility hard coating layers are particularly vulnerable to external impacts such as bending and may cause cracking or partial chipping problems. Therefore, in order to secure both flexibility and wear resistance, a method of increasing the wear resistance of the hard coating layer without increasing the content of hard particles in the hard coating composition is required.

An object of the present invention is to provide a hard coating composition that can improve the wear resistance of the hard coating layer without increasing the content of hard particles in the hard coating composition in order to improve both the flexibility and wear resistance of the hard coating layer.

Hard coating composition according to an embodiment of the present invention for achieving the above object comprises a surface-type additive containing a polysiloxane compound, characterized in that the rheology-index is determined by the following formula 1 1.0 to 1.2 .

[Equation 1]

Rheology-index = (viscosity at low shear rate) / (viscosity at high shear rate)

The hard coating composition is a colloidal silica (Colloidal silica); And alkoxysilane (Alkoxysilane); may include.

The colloidal silica and the alkoxysilane may be sol-gel reacted.

The surface additive includes polyether modified polysiloxanes; And an ether compound.

The surface additive may be included in a ratio of 0.05 to 0.2 parts by weight based on 100 parts by weight of the hard coating composition.

The rheology-index may be the viscosity of the hard coating composition in the viscosity of the hard coating composition in the range of 0.1 to 100 s ^-1 and a low shear rate of from 100 to 1000 s ^-1 and a shear rate of inconsistency.

Molded film according to another embodiment of the present invention for achieving the above object is a substrate layer; And a hard coating layer formed on the substrate layer, wherein the hard coating layer includes a surface-type additive including a polysiloxane compound, and has a rheology-index of 1.0 to 1.2 determined by Equation 1 below. Characterized in that formed.

[Equation 1]

Rheology-index = (viscosity at low shear rate) / (viscosity at high shear rate)

The surface additive may be included in a ratio of 0.05 to 0.2 parts by weight based on 100 parts by weight of the hard coating composition.

The rheology-index may be the ratio of the viscosity of the hard coating composition at low shear rates of 0.1 to 100 s ⁻¹ and the viscosity of the hard coating composition at high shear rates of 100 to 1000 s ⁻¹ .

The hard coating layer may have a thickness of 2 μm to 15 μm.

The hard coating composition may be thermally cured at 120 ℃ to 200 ℃ to form the hard coating layer.

A primer layer may be present between the substrate layer and the hard coating layer to improve interlayer adhesion.

The hard coating composition of the present invention includes a surface additive and has a rheology-index in the range of 1.0 to 1.2 to improve wear resistance after curing without increasing the hard particle content.

In particular, since the hard coating composition of the present invention has a rheology-index in the range of 1.0 to 1.2, its physical properties are very similar to those of the ideal fluid. The hard coating composition of the present invention is improved in the resulting flow properties having the same properties as the ideal fluid, the surface of the hard coating layer is slippery as a result of improved flow properties of the composition. The heart coating layer has a slippery surface, which is scratch resistant and high wear resistance.

Therefore, the hard coating layer formed of the hard coating composition of the present invention has both improved wear resistance and flexibility to withstand scratches from the outside and is also resistant to external impact such as bending.

1 briefly illustrates a cross section of a molded film according to an embodiment of the present invention.

Figure 2 briefly shows a cross section of a molded film according to another embodiment of the present invention.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, only the present embodiments to make the disclosure of the present invention complete, and common knowledge in the art to which the present invention pertains. It is provided to fully inform the person having the scope of the invention, which is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

Hard coating  Composition

Hard coating composition according to an embodiment of the present invention comprises a surface-type additive comprising a polysiloxane compound, characterized in that the rheology-index is determined by the following formula (1) is 1.0 to 1.2.

[Equation 1]

Rheology-index = (viscosity at low shear rate) / (viscosity at high shear rate)

Hereinafter, each component included in the hard coating composition of the present invention will be described in detail.

Surface additive

The surface additive according to one embodiment of the present invention includes a polysiloxane compound. The surface additive is located at the interface between the substrate and the hard coating and at the interface between the hard coating and the outside air of the hard coating layer so that the hard coating layer can form a uniform interface.

Since the hard coating layer has a uniform interface, the generation of flow marks or uneven surfaces on the hard coating layer is minimized during the application of the hard coating composition.

One example of a flow mark or non-uniform surface on the hard coat layer is the phenomenon of cratering (Cratering). Crater phenomenon may occur when foreign matter enters the applied hard coating composition. Since the foreign matter may be small particles such as fine dust present in the air, it is practically difficult to completely exclude the inflow of the foreign matter in the hard coating layer formation process. Therefore, there may be many non-uniform faces in the form of craters on the hard coat layer.

Protruding portions that are present on non-uniform surfaces such as flow marks or craters on the hardcoat layer are susceptible to scratching and thus reduce the wear resistance of the hardcoat layer. The hard coat layer of the present invention has excellent wear resistance as compared to the conventional hard coat layer because there is no protruding portion on the surface as a result of forming a uniform interface by including a surface type additive.

Surface-type additive according to an embodiment of the present invention is a polyether modified polysiloxane; And ether compounds.

Polyether modified polysiloxane means that there is an ether bond in the side chain of the polysiloxane. Ether bonds present in the side chains of the polysiloxanes affect the polarity of the polysiloxanes. Specifically, the ether bonds present in the polysiloxane side chain exist in the form of ethylene oxide or propylene oxide, and as the number of ethylene oxides present in the polysiloxane side chain increases, the polysiloxane becomes polar, and the polysiloxane side chain As the number of propylene oxides present increases, the polysiloxanes become nonpolar. Thus, those who wish to prepare the hard coating composition according to the present invention can adjust the polarity of the polyether modified polysiloxane according to the polarity of the hard coating composition, which allows the surface additive to be more easily dissolved in the hard coating layer.

The ether compound may preferably contain a hydrophilic group in the molecule. For example, the ether compound may be dipropylene glycol monomethyl ether. Ether compounds are generally nonpolar and well soluble in organic solvents, but can also be dissolved in aqueous solvents by hydrogen bonding of water and oxygen molecules present in ether bonds and hydrophilic groups containing hydrophilic groups in the molecule. That is, ether compounds help the surface additives to be dissolved in both organic and aqueous solvents.

According to one embodiment of the present invention, the surface additive may be included in a ratio of 0.05 to 0.2 parts by weight based on 100 parts by weight of the hard coating composition. If the hard coating composition contains less than 0.05 part by weight of the surface type additive, the surface uniformity effect of the hard coating layer by the surface type additive may be insignificant. In addition, when the surface-type additives are included in excess of 0.2 parts by weight, there is a problem of reducing adhesive strength and turbidity after hard-coating heat curing, and cracks are more likely to occur.

Rheology -Indices

Rheology-index is a measure of how far the physical properties of a fluid deviate from that of an ideal fluid. In the case of the ideal fluid, the rheology-index is 1.0 and the rheology-index is greater than 1.0, the physical properties of the fluid are different from those of the ideal fluid.

The rheological index can be calculated by measuring the viscosity. Specifically, the rheology-index is the ratio of the viscosity of the fluid at low shear rate and the viscosity of the fluid at high shear rate, as shown in Equation 1 below.

[Equation 1]

Rheology-index = (viscosity at low shear rate) / (viscosity at high shear rate)

At this time, the range of low shear rate and high shear rate varies depending on the fluid. Low shear rate of the hard coating composition according to an embodiment of the present invention means 0.1 to 100s ^-1 , high shear rate means 100 to 1000s ^-1 . The shear rate range is the most suitable range to determine whether the hard coating composition behaves like an ideal fluid. That is, 100s ^- when measuring the low shear rate at a shear rate of greater than ^1, or a high shear rate of 100s ^-1 under measuring shear rate rheology - may lower the reliability of the index.

Since the hard coating composition according to the present invention has a rheology-index of 1.0 to 1.2, the physical properties of the fluid are very similar to those of the ideal fluid. The hard coating composition according to the invention forms a very slippery surface when cured. Since the slippery surface of the hard coating layer has a low surface friction, less scratches occur when an external object collides with the hard coating layer. In addition, low surface friction prevents contaminants from remaining on the surface of the hard coat layer for a long time.

Colloidal  Silica and Alkoxysilane

According to an embodiment of the present invention, the hard coating composition may include colloidal silica and alkoxysilane.

Colloidal silica refers to silica particles derived from a dispersion or sol in which the particles do not precipitate from the dispersion over a relatively long period of time. Colloidal silica is a chemically stable hard particle that increases the wear resistance of the hard coat layer. Colloidal silica can be prepared from sodium silicate by ion exchange and acid-neutralization. Colloidal silica suitable for use in the hard coating compositions of the present invention has a diameter of 45 nm to 80 nm. The range is such that the colloidal silica can act as hard particles in the hard coat layer while not significantly reducing the flexibility of the hard coat layer. That is, when the diameter of the colloidal silica particles is less than 45nm it is insufficient to act as hard particles in the hard coating layer to improve the wear resistance of the hard coating layer. In addition, when the diameter of the colloidal silica particles exceeds 80nm, the flexibility of the hard coating layer is reduced by the colloidal particles, cracks may occur in the hard coating layer.

Alkoxysilanes perform the function of crosslinking between colloidal silica particles. Substances which can be used as the alkoxysilane compound include (3-acryloxypropyl) trimethoxysilane (APTMS), 3-aminopropyltriethoxysilane (APTES), 3-aminopropyltrimethoxysilane (APTMS), 3 -Glycidoxypropyltrimethoxysilane (GOPTMS), 3-isocyanatopropyltriethoxysilane (ICPTES), 3-methacryloxypropyltrimethoxysilane (MPTMS), methyltriethoxysilane (MTES), Methyltrimethoxysilane (MTMS), vinyltriethoxysilane (VTES), 3-mercaptopropyltriethoxysilane (MPTES), 3-mercaptopropyltrimethoxysilane (MPTMS) and combinations thereof It may be at least one selected from, but is not limited thereto. Alkoxysilanes have the advantage of being environmentally friendly because hydrogen chloride (HCl) does not occur as a byproduct during the reaction, compared to chlorine-based coupling agents commonly used as curing agents in the industry.

According to an embodiment of the present invention, colloidal silica and alkoxysilane may be combined with each other by a sol-gel reaction to form an organic-inorganic hybrid composite close to glassy state. The sol-gel process uses a metal alkoxide precursor which has excellent reactivity at room temperature instead of the conventional high temperature melting method of silicate in the production of uniform ceramic or glass products, and then reacts with gel in colloidal sol, followed by drying and curing. It is a method of obtaining a uniform inorganic oxide through the process. According to the sol-gel process, the product can be obtained at a much lower temperature than the conventional high temperature melting method, high chemical uniformity can be obtained, and a special shaped product such as thin film or nanoparticles can be obtained. The sol-gel process can economically prepare functional coating solutions, metal oxide nanoparticles, and functional ceramics through hydrolysis and condensation reactions in solution. Therefore, according to the sol-gel process, a product having high chemical uniformity can be obtained, and in particular, an organic-inorganic hybrid composite material having an intermediate characteristic of an inorganic material and an organic material can be obtained by adding and reacting an organic material to an inorganic precursor. The organic-inorganic hybrid composite material prepared by the sol-gel process is a new material having both advantages such as wear resistance and transparency of the inorganic material, and flexibility and moldability of the organic material.

That is, in one embodiment of the present invention, the hard coating layer formed by the sol-gel reaction of the colloidal silica, which is an inorganic material, and the alkoxysilane, which is an organic material, has both wear resistance by colloidal silica and flexibility by alkoxysilane.

Molding Film (10)

Referring to FIG. 1, a molded film 10 according to an embodiment of the present invention may include a substrate layer 100; Hard coating layer 200 formed on the substrate layer 100; wherein the hard coating layer includes a surface-type additive including a polysiloxane compound, and has a rheology-index 1.0 determined by Equation 1 below. To 1.2 is characterized in that formed of a hard coating composition.

Hereinafter, each configuration included in the molded film 10 of the present invention will be described in detail.

Substrate layer (100)

The material constituting the base layer 100 may vary depending on the use of the molded film 10, but generally, it is required to have excellent strength and high transmittance.

The base layer 100 may include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polycarbonate (PC), polyethylene (PE) ), Poly propylene (PP) or a combination thereof is preferably used.

Hard coating  Floor (200)

The hard coating layer 200 is formed by curing the hard coating composition according to the present invention. Details of the hard coating composition forming the hard coating layer 200 are as described above.

According to one embodiment of the present invention, the surface additive may be included in a ratio of 0.05 to 0.2 parts by weight based on 100 parts by weight of the hard coating composition. If the hard coating composition contains less than 0.05 part by weight of the surface type additive, the surface uniformity effect of the hard coating layer by the surface type additive may be insignificant. In addition, when the surface type additive is included in excess of 0.2 parts by weight, there is a problem of increasing the production cost of the hard coating composition, the adhesion of the hard coating composition to the substrate may be reduced.

Low shear rate of the hard coating composition according to an embodiment of the present invention means 0.1 to 100s ^-1 , high shear rate means 100 to 1000s ^-1 . The shear rate range is the most suitable range to determine whether the hard coating composition behaves like an ideal fluid. That is, 100s ^- when measuring the low shear rate at a shear rate of greater than ^1, or a high shear rate of 100s ^-1 under measuring shear rate rheology - may lower the reliability of the index.

Hard coating layer 200 according to an embodiment of the present invention may have a thickness of 2㎛ to 20㎛. When the thickness of the hard coating layer 200 is less than 2㎛ may be insufficient substrate protective effect by the hard coating layer 200, there is a fear that the substrate layer 100 is damaged by a deep scratch. In addition, when the thickness of the hard coating layer 200 exceeds 20㎛, the hard coating layer 200 is too thick can increase the weight of the entire molding film 10. When the weight of the molded film 10 is increased, the usability of the molded film 10 may be degraded. In addition, since the hard coating layer 200 thicker than 20 μm takes a long time to harden, the efficiency of the manufacturing process of the molded film 10 may be reduced.

The hard coat layer 200 may be preferably formed by heat curing the hard coat composition. According to an embodiment of the present invention, the temperature at which thermal curing of the hard coating composition is performed is 120 ° C to 200 ° C. If the temperature at which the thermal curing is performed is less than 120 ° C., the thermal curing time is excessively long, so there is a problem in productivity. In addition, when the temperature at which the thermal curing is performed exceeds 200 ° C., the base layer 100 may be deformed during the thermal curing process.

primer  Floor (300)

According to the exemplary embodiment of the present invention disclosed in FIG. 2, a primer layer 300 may be present between the substrate layer 100 and the hard coating layer 200 to improve interlayer adhesion.

The primer layer 300 allows the substrate layer 100 and the hard coat layer 200 to adhere well to each other. To form the primer layer 300 is selected from the group consisting of polyurethane resin, polyacrylic resin, polystyrene resin, polyamide, chlorinated polyolefin resin, chlorinated ethylene-vinyl acetate copolymer resin, rubber resin or a combination thereof Preference is given to using one or more.

The following presents specific embodiments of the present invention. However, the embodiments described below are merely for illustrating or explaining the present invention in detail, and the present invention is not limited thereto.

< Example >

<Production of Molded Film>

In order to manufacture molded films of Examples and Comparative Examples of the present invention, polycarbonate (PC) having a thickness of 100 μm was used as a base layer. On the substrate layer, a primer layer made of a hard coating composition and a PMMA resin was applied and thermally cured at 130 ° C. for 10 minutes in an oven. The hard coat layers of Examples and Comparative Examples had a thickness of 10 μm. The hard coating compositions of Examples and Comparative Examples both included Ludox® LS-30 colloidal silica and vinyl trimethoxy silane (VTMS), and the colloidal silica and VTMS were subjected to sol-gel reaction under acidic conditions.

The hard coating compositions of Examples and Comparative Examples differ in whether or not the surface type additives are included. In Examples 1 and 2, the surface type additives were added to the hard coating composition during the sol-gel reaction of the colloidal silica and the alkoxysilane. 0.2 parts by weight and 0.15 parts by weight were added. However, 0.01 parts by weight of the surface type additive was added to the hard coating composition of Comparative Example 1, and no surface type additive was added to the hard coating compositions of Comparative Examples 2 and 3. However, in the case of Comparative Example 3, the content of the colloidal silica was increased to twice the content of the colloidal silica in the other examples and comparative examples.

< Rheology Index Evaluation

Comparative example and embodiment rheology - to evaluate the index, by measuring the viscosity of the hard coating composition at a shear rate of 80s ^-1 and the viscosity of the hard coating composition at a shear rate of 400s ^-1 was determined the ratio. The viscosity was measured using a Rotating Concentric-Cylinder Viscometer.

<Evaluation of wear resistance>

In order to evaluate the abrasion resistance of the molded films of Comparative Examples and Examples, the degree of abrasive wear was evaluated through a Taber Abrasion test according to ASTM D 1044-99. Specifically, the haze of the molded film before and after grinding the molded film was measured using a CS10F wear wheel having a 500 g × 2ea load to calculate the change amount Δhaze before and after the grinding. The smaller the amount of change in the degree of clouding before and after grinding, the better the wear resistance.

<Evaluation of flexibility>

In order to evaluate the flexibility of the molded films of Comparative Examples and Examples, a 3-point bending test was conducted based on ASTM D790 and the flexural modulus was measured. The higher the flexural modulus, the better the flexibility of the molded film and the hard coat layer.

The wear resistance and rheology-index evaluation results of the molded films of Examples and Comparative Examples are shown in Table 1 below.

	Colloidal Silica Content	Surface additive content	Rheology-Index	Δhaze	Wear Resistance Rating	Flexural modulus
Example 1	80	0.2	1.18	7.8	Great	3.7
Example 2	80	0.15	1.09	7.0	Great	3.64
Comparative Example 1	80	0.01	1.31	9.5	Under	3.6
Comparative Example 2	80	0	1.27	8.7	Under	3.61
Comparative Example 3	160	0	1.8	7.2	Great	2.8

As can be seen in Table 1, the molded films of Examples 1 and 2, each containing 0.2 parts by weight and 0.15 parts by weight of the surface-type additive, and the rheology-index 1.18 and 1.09, respectively, were excellent in the wear resistance of the hard coating layer. . The molded film hard coat layers of Comparative Examples 1 and 2 had a Δhaze value higher than the Δhaze value of the molded film hard coat layer of the examples. This indicates that the surface coating additive is not sufficiently contained, and the high rheology-index hard coating layer of the comparative example is susceptible to grinding wear. In addition, in Comparative Example 3, the rheology-index was high, and no surface-type additive was included, but the colloidal silica content was very high, and thus the wear resistance evaluation was excellent.

Examples 1 and 2 and Comparative Examples 1 and 2 having the same colloidal silica content were excellent in flexural modulus, which is a measure of flexibility of the hard coating layer. However, in Comparative Example 3, the colloidal silica, which is hard particles, was contained in excess, resulting in low flexural modulus. This shows that the flexural modulus, that is, the flexibility of the hard coat layer may decrease when the content of the colloidal silica is increased in order to increase wear resistance as in Comparative Example 3.

The foregoing description of the present invention is intended for illustration, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

Claims (12)

1. A surface type additive comprising a polysiloxane compound,

   Rheology index determined by Equation 1 below 1.0 to 1.2, characterized in that the wear resistance after curing is improved

   Hard coating composition.

   [Equation 1]

   Rheology-index = (viscosity at low shear rate) / (viscosity at high shear rate)
2. The method of claim 1,

   The hard coating composition is

   Colloidal silica; And

   Alkoxysilane; characterized in that it comprises a

   Hard coating composition.
3. The method of claim 2,

   The colloidal silica and the alkoxysilane is characterized in that the sol-gel reaction

   Hard coating composition.
4. The method of claim 1,

   The surface additive

   Polyether modified polysiloxanes; And

   Ether compound; characterized in that it further comprises

   Hard coating composition.
5. The method of claim 1,

   The surface additive is included in a ratio of 0.05 to 0.2 parts by weight based on 100 parts by weight of the hard coating composition.

   Hard coating composition.
6. The method of claim 1,

   The rheology-index is

   Characterized by the ratio of the viscosity of the hard coating composition at low shear rates of 0.1 to 100 s ⁻¹ and the viscosity of the hard coating composition at high shear rates of 100 to 1000 s ⁻¹ .

   Hard coating composition.
7. Substrate layer; And

   And a hard coating layer formed on the substrate layer.

   The hard coating layer is

   A surface type additive comprising a polysiloxane compound,

   Rheology-index of 1.0 to 1.2, determined by Equation 1

   Characterized in that formed of a hard coating composition

   Molding film.

   [Equation 1]

   Rheology-index = (viscosity at low shear rate) / (viscosity at high shear rate)
8. The method of claim 7, wherein

   The surface additive is included in a ratio of 0.05 to 0.2 parts by weight based on 100 parts by weight of the hard coating composition.

   Molding film.
9. The method of claim 7, wherein

   The rheology-index is

   Characterized by the ratio of the viscosity of the hard coating composition at low shear rates of 0.1 to 100 s ⁻¹ and the viscosity of the hard coating composition at high shear rates of 100 to 1000 s ⁻¹ .

   Molding film.
10. The method of claim 7, wherein

    The hard coating layer has a thickness of 2 μm to 20 μm.

    Molding film.
11. The method of claim 7, wherein

    The hard coating composition is heat-cured at 120 ℃ to 200 ℃ characterized in that to form the hard coating layer

    Molding film.
12. The method of claim 7, wherein

    A primer layer exists between the base layer and the hard coating layer to improve interlayer adhesion.

    Molding film.

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