CN114350271A

CN114350271A - Sheet for preventing flying and decoration and mobile equipment comprising same

Info

Publication number: CN114350271A
Application number: CN202110662232.3A
Authority: CN
Inventors: 柳永彬; 姜熙民; 朴相炫; 李扃旻; 冰广殷
Original assignee: SKC Hi Tech and Marketing Co Ltd
Current assignee: SK Microworks Solutions Co Ltd
Priority date: 2020-10-12
Filing date: 2021-06-15
Publication date: 2022-04-15
Also published as: KR102501201B1; KR20220048258A

Abstract

The present invention relates to a sheet exhibiting a plurality of reflection colors according to a viewing angle and capable of preventing scattering of a glass cover or the like of a mobile device, and a mobile device including the same. The sheet includes a three-dimensional color coating layer and an adhesive layer, and can be applied to various products such as mobile devices, displays, automobiles, household appliances, and the like through anti-scattering and decorative purposes.

Description

Sheet for preventing flying and decoration and mobile equipment comprising same

Technical Field

The present invention relates to a sheet for scattering prevention and decoration, which is suitable for use in mobile devices and the like. More particularly, the present invention relates to a sheet exhibiting a plurality of reflection colors according to a viewing angle and capable of preventing scattering of a glass cover or the like of a mobile device.

Background

In the field of electric and electronic devices, display devices have been developed in various forms in consideration of various factors such as the purpose of use, portability, and convenience, and particularly, consumers have been studying various designs of displays because they pay attention to the design according to the use of the displays. Recently, designs that have attracted attention in the field of electric and electronic devices are metallic designs, and metallic designs are widely applied to colors, appearances, and the like of mobile devices, communication electronic devices, and the like that have recently come into the market. Although metals are materials that have attracted attention in terms of design because of their inherent luster and excellent brightness, they have disadvantages such as blocking radio waves, heavy weight, and high manufacturing cost.

In order to compensate for the above disadvantages, displays using glass or transparent plastic instead of metal are being developed. Compared with metal, glass or plastic materials, the material has the advantages of low preparation cost and light weight. However, it has a fatal disadvantage of strength reduction, and therefore, in order to improve the design of displays made of the above materials, a method of applying an anti-scattering film is being studied so as to enable color to be realized while increasing strength and enhancing impact resistance and safety at the time of damage.

As an example, korean laid-open patent No. 2014-0110325 discloses an anti-scattering film including a hard coat layer including a transparent film and an azo (azo) -based dye, and korean laid-open patent No. 2015-0096860 includes a hard coat layer including a colored dye having a maximum absorption rate of 400nm to 700nm and a transparent conductive film including the same. However, the above patent discloses only physical properties related to transparency, durability, and the like of the film, and does not disclose contents related to design, and particularly, does not disclose contents related to realization of a plurality of colors depending on viewing angles.

Documents of the prior art

Patent document 1: korean laid-open patent No. 2014-0110325,

patent document 2: korean laid-open patent No. 2015-0096860.

Disclosure of Invention

Technical problem

A general anti-scattering film is a protective film for preventing glass from being damaged, and recently, colors and designs are introduced into the anti-scattering film in order to impart various color and decorative functions to products. However, at present, a two-dimensional color is expressed only by a single color or a gradation of 1 to 2 colors, and a stereoscopic color cannot be realized.

In contrast, the present inventors have found through studies that a sheet exhibiting a change in reflection color according to a viewing angle and having excellent anti-scattering properties can be realized by combining a stereoscopic color coating layer using cholesteric liquid crystal (cholesteric liquid crystal), an adhesive layer, a pattern layer, a printed layer, and the like.

Accordingly, an object of the present invention is to provide a sheet that exhibits a plurality of reflection colors according to a viewing angle and can prevent scattering of a glass cover or the like of a mobile device.

Technical scheme

According to the above object, the present invention provides a sheet for scattering prevention and decoration comprising: a substrate layer; the stereoscopic colored coating is formed above the base material layer; and an adhesive layer formed on the stereoscopic color coating layer, wherein the stereoscopic color coating layer includes a cholesteric liquid crystal polymer having a nematic liquid crystal (nematic liquid crystal) component and a chiral dopant (chiral dopant) as constituent components.

Also, the mobile device provided by the present invention includes: a cover made of glass or transparent plastic material; and the sheet for preventing scattering and decoration is attached to the cover.

Also, the present invention provides a stereoscopic color coating film comprising: a substrate layer; and a stereoscopic color coating layer formed above the base material layer, the stereoscopic color coating layer including a cholesteric liquid crystal polymer having a nematic liquid crystal component and a chiral dopant as constituent components.

ADVANTAGEOUS EFFECTS OF INVENTION

The sheet of the present invention includes a three-dimensional color coating layer including a cholesteric liquid crystal polymer having a nematic liquid crystal component and a chiral dopant as constituent components, and an adhesive layer, and can exhibit various reflection colors according to viewing angles and prevent scattering of a glass cover or the like of a mobile device. The sheet further includes a primer layer, a pattern layer, a reflective layer and a printed layer, and the color and reflectance are additionally adjusted by the functional layers, thereby further realizing various designs.

In particular, the stereoscopic color coating layer can be formed through a wet coating process, and the generation of cracks due to deformation can be reduced and the mass productivity and the production yield can be improved compared to the inorganic deposition layer formed through sputtering in order to realize the conventional metallic texture. Since the sheet can exhibit a three-dimensional color according to a viewing angle and can be attached to a bent glass to improve strength, the sheet can be applied to various products such as mobile devices, displays, automobiles, home appliances, and the like through anti-scattering and decorative purposes.

Drawings

Fig. 1 is an exploded perspective view of a sheet for fly-away prevention and decoration according to an embodiment of the present invention.

Fig. 2 and 3 are graphs showing changes in reflection color between a conventional product and a stereoscopic color coating film of the present invention according to a viewing angle.

Fig. 4 is a graph showing a difference in reflection color of a stereoscopic color coating film having a curved surface according to a viewing angle.

Fig. 5 is a view of realizing a three-dimensional color coating film of a plurality of colors.

Fig. 6 is a graph showing a transmission spectrum and a reflection spectrum according to the amount of the chiral dopant added.

Fig. 7 is a graph showing changes in thickness and reflectance of a coating layer according to the solid content of a coating composition.

Fig. 8 is a graph showing a change in reflection spectrum according to the solid content of the coating composition.

Fig. 9 is a diagram showing an experimental method of inducing cracks by stretching a film sample.

Fig. 10 and 11 are views of the inorganic deposition layer and the three-dimensional color coating layer after stretching by 1% and 3%, respectively.

Fig. 12 is a view of a multi-colored sheet for fly-away and decoration.

Fig. 13 is a view showing a change in reflection color due to inclination of a sheet for scattering prevention and decoration of an example.

Fig. 14 is a diagram showing a molecular arrangement structure of a cholesteric liquid crystal polymer.

Fig. 15 is a schematic diagram showing circularly polarized light with respect to a cholesteric liquid crystal polymer.

Description of reference numerals

10: sheet for preventing flying and decoration

20: cover of mobile device 21: a flat glass substrate having a plurality of flat surfaces,

100: bonding layer 201: a three-dimensional color film-coated test piece,

210: stereoscopic color coating 220: a base material layer,

300: pattern layer 400: a printing layer is arranged on the surface of the substrate,

l0: initial length L: the length of the stretched film is determined by the length of the film,

w: width of

Detailed Description

The present invention will be described in further detail below with reference to the accompanying drawings. The size, interval, etc. in the drawings may be exaggerated for easy understanding, and may be omitted to show matters obvious to those skilled in the art to which the present invention pertains.

In the following description, it should be understood that when a certain structural element is disposed above or below another structural element, all cases where other structural elements are present or absent between the structural elements are included.

In the present specification, when a certain structural element is "included", it means that other structural elements may be included in addition to the structural element unless specifically stated to the contrary.

Sheet for preventing flying and decoration

The sheet of the present invention can be used for fly-away prevention and decoration, and includes: a substrate layer; the stereoscopic colored coating is formed above the base material layer; and an adhesive layer formed on the stereoscopic color coating layer, wherein the stereoscopic color coating layer includes a cholesteric liquid crystal polymer having a nematic liquid crystal component and a chiral dopant as constituent components.

As an example, cholesteric liquid crystal polymers are applied to a reflective color filter of a conventional Liquid Crystal Display (LCD), but are difficult to be applied to actual products due to a problem of discoloration of a viewing angle, and currently, are only applied to some fields of pearl products and infrared cut filter sheets for cosmetics, and thus have very limited availability. However, the present invention is advantageous in that the problem of discoloration of the viewing angle due to the molecular arrangement of the cholesteric liquid crystal polymer is utilized, and is applied to the fields of decoration and fly-away prevention films through a switching concept.

In particular, the three-dimensional color coating layer included in the sheet of the present invention can be formed by a wet coating process, and compared to an inorganic vapor deposition layer formed by sputtering in order to realize a conventional metallic texture, the generation of cracks due to deformation can be reduced and the process capability and production yield can be improved. Specifically, in the case where the sheet is attached to a glass substrate after being stretched and left to stand at a temperature of 85 ℃ for 72 hours, the minimum stretching ratio at which cracks are generated in the stereoscopic color coating layer may be more than 3%, specifically, more than 5%. In contrast, in the case of the inorganic vapor-deposited layer formed by sputtering, when it is stretched by 3%, cracks can be easily generated.

Since the sheet of the present invention can exhibit a three-dimensional color according to a viewing angle and can be attached to curved glass to improve strength, it can be suitably used for various products such as mobile devices, displays, automobiles, home appliances, and the like through anti-scattering and decorative purposes.

The sheet may further include a pattern layer disposed below the base material layer; and a printing layer disposed below the pattern layer. That is, the pattern layer and the print layer may be formed in this order along a plane direction in which the three-dimensional color coat layer is not formed on both surfaces of the base layer.

Fig. 1 is an exploded perspective view of a sheet for fly-away prevention and decoration according to an embodiment of the present invention. Referring to fig. 1, a sheet 10 according to an example may include an adhesive layer 100, a stereoscopic color coating layer 210, a base material layer 220, a pattern layer 300, and a printing layer 400, which are sequentially stacked, and the sheet 10 may be attached to a cover 20 of a mobile device through the adhesive layer 100. Also, the sheet may further include functional layers, for example, a primer layer, a reflective layer, etc., between the layers.

As described above, the sheet further includes the primer layer, the pattern layer, the reflective layer, and the printed layer, and various designs can be further realized by additionally adjusting the color and the reflectance through the functional layer and imparting the metallic texture.

Hereinafter, each structure will be specifically described.

Substrate layer

The substrate layer is used for supporting the bottom layer of other functional layers.

The substrate layer may contain a polymer resin, and specifically may contain a transparent polymer resin. For example, the substrate layer may include one or more polymer resins selected from the group consisting of polyethylene terephthalate (PET), Polyimide (PI), cycloolefin polymer (COP), polyethylene naphthalate (PEN), polyether sulfone (PES), Polycarbonate (PC), and polypropylene (PP).

The substrate layer is preferably polyethylene terephthalate (PET) or oriented polypropylene (OPP) for the reason that it needs to be stable in factors such as electrostatic charge that can inhibit coating uniformity while not causing a reaction with a chemical substance applied to the surface.

The substrate layer may have excellent strength so as to prevent the tempered glass of the touch panel from scattering.

The base material layer may be a uniaxially stretched film, and for example, a film stretched 2 to 5 times in the longitudinal direction MD or the width direction TD. Alternatively, the base material layer may be a biaxially stretched film, for example, a film stretched 2 to 5 times in the longitudinal direction MD and 2 to 5 times in the width direction TD.

Also, the substrate layer may have high transparency so as not to impair optical characteristics. For example, the total light transmittance of the base material layer may be 55% or more, specifically 70%.

The thickness of the substrate layer may be 10 to 200 μm, specifically 23 to 100 μm.

The substrate layer may further include organic particles or inorganic particles on the surface thereof. The organic particles or inorganic particles as described above may function as an anti-blocking agent. The size of the organic particles or inorganic particles may be 0.1 μm or more, for example, 0.1 μm to 5 μm or 0.1 μm to 1 μm.

Three-dimensional color coating

The stereoscopic color coating layer comprises a cholesteric liquid crystal polymer, and the cholesteric liquid crystal polymer comprises a nematic liquid crystal component and a chiral dopant as composition components.

The nematic liquid crystal component may be a reactive mesogen (mesogen) compound, and may have, for example, an aromatic group or an acrylate group. For example, the nematic liquid crystal composition may include at least one of the compounds of the following chemical formulae 1 to 6:

chemical formula 1:

chemical formula 2:

chemical formula 3:

chemical formula 4:

chemical formula 5:

chemical formula 6:

the chiral dopant may be a right-handed chiral (right-handed) substance or a left-handed chiral (left-handed) substance. Also, the chiral dopant may have an aromatic group and an acrylate group. For example, the chiral dopant may include at least one of the compounds of the following chemical formulae 7 to 10:

chemical formula 7:

chemical formula 8:

chemical formula 9:

chemical formula 10:

the content of the chiral dopant may be 1 part by weight or more, 2 parts by weight or more, 3 parts by weight or more, 3.5 parts by weight or more, 4 parts by weight or more, or 4.5 parts by weight or more, based on 100 parts by weight of the nematic liquid crystal component. Alternatively, the content of the chiral dopant may be 10 parts by weight or less, 7 parts by weight or less, 5.5 parts by weight or less, 5 parts by weight or less, 4.5 parts by weight or less, or 4 parts by weight or less, based on 100 parts by weight of the nematic liquid crystal component. For example, the chiral dopant may be contained in an amount of 2 to 10 parts by weight, based on 100 parts by weight of the nematic liquid crystal component. As a more detailed example, the content of the chiral dopant may be 3 to 5.5 parts by weight based on the weight of the cholesteric liquid crystal polymer.

Various colors can be realized by the combination of the nematic liquid crystal component and the chiral dopant. Fig. 5 is a view of realizing a three-dimensional color coating film of a plurality of colors. In particular, the final reflection wavelength of the stereoscopic color coating may be determined according to the content of the chiral dopant.

Fig. 6 shows an example of transmittance and reflectance at each wavelength according to the content (parts by weight) of the chiral dopant based on 100 parts by weight of the nematic liquid crystal component. Table 1 below shows an example of the wavelength (peak wavelength) of reflected light with respect to light that perpendicularly enters the front surface of the stereoscopic color coating film, according to the change in the content of the chiral dopant.

TABLE 1

Content of chiral dopant	Reflection wavelength
		3.1 parts by weight	750nm
3.5 parts by weight	690nm
		4.4 parts by weight	530nm
4.7 parts by weight	490nm
		5.1 parts by weight	450nm

The wavelength of the reflected light may be 450nm to 750nm with respect to light perpendicularly incident to the front surface of the stereoscopic color coating film. For example, the wavelength of the reflected light may be 450nm to 500nm, 500nm to 550nm, 550nm to 600nm, 600nm to 650nm, 650nm to 700nm, or 700nm to 750 nm. The reflectance at the wavelength (peak wavelength) of the reflected light may be 40% or more, 45% or more, or 50% or more, specifically, 40% to 80%.

The stereoscopic colored coating may further include a photoinitiator. For example, the photoinitiator may be IG184, IG907, IG8919, TPO, or the like. The content of the above photoinitiator may be 1 to 10 parts by weight with respect to 100 parts by weight of the cholesteric liquid crystal polymer and the chiral dopant in total, but may be varied depending on the kind and reactivity of the photoinitiator and the thickness of the coating layer.

As shown in fig. 14, the cholesteric liquid crystal polymer is aligned by a nematic liquid crystal composition having a long molecular structure, a chiral dopant is added thereto and rotationally aligned in a helical manner, a pitch p, which is a rotation period of the helix, is artificially determined according to the content of the dopant, and light having a wavelength corresponding to the pitch is selectively reflected.

As shown in fig. 15, for example, when a plurality of cholesteric liquid crystal polymer molecules M are arranged in a clockwise direction in a spirally rotating manner, there occurs a phenomenon in which right-handed circularly polarized light (R-CPL) is reflected by polarization of incident light having the same wavelength as the molecular arrangement pitch p, and left-handed circularly polarized light (L-CPL) is transmitted together with light having a wavelength different from the pitch p.

Thus, the stereoscopic color can be expressed by changing the wavelength of the reflected light according to the viewing angle (incident angle). Fig. 4 is a graph showing a difference in reflection color of a stereoscopic color coating film having a curved surface according to a viewing angle.

For example, the above-described stereoscopic color coating may satisfy the following formula (1):

λ＝n×p×cos[sin^-1(sinα/n)]...(1)

in the above formula, n is the average refractive index of the stereoscopic color coating layer, p is the pitch of the period in which the cholesteric liquid crystal polymer molecules are arranged, α is the incident angle of incident light, and λ is the wavelength of reflected light.

If the incident angle of the incident light with respect to the stereoscopic color coating is vertical, the following formula (2) can be satisfied:

λ＝n×p...(2)

in the above formula, n is the average refractive index of the stereoscopic color coating layer, and p is the pitch of the period of the cholesteric liquid crystal polymer molecular alignment.

As described above, the sheet of the present invention exhibits different colors depending on viewing angles, and thus, can exhibit various three-dimensional colors. For example, when the sheet of the present invention is viewed from the front, or when viewed obliquely at a prescribed angle from the front, mutually different colors may be expressed. Specifically, when a change of 5 degrees or more is generated with respect to the observation angle of the sheet, for example, when the change is 5 degrees to 40 degrees, the change in a × value of the reflected color based on the CIE Lab color system may be 5 degrees or more, more specifically, 10 degrees or more or 15 degrees or more. As a specific example, the change in the value a may be 5 to 45 or 10 to 25. In this case, the observation angle may be an angle based on the plane direction of the sheet, and the value a may be a measured value for a transmitted color.

The thickness of the three-dimensional color coat layer is 1 μm or more, 1.5 μm or more, 2 μm or more, or 2.5 μm or more, and may be 10 μm or less, 5 μm or less, 3 μm or less, 2.5 μm or less, or 2 μm or less. Specifically, the thickness of the above-described stereoscopic color coating layer may be 1 μm to 10 μm. Since the reflectance of the above-described stereoscopic color coating becomes different depending on the thickness, the thickness of the stereoscopic color coating can be adjusted according to the reflectance of the target sheet.

Adhesive layer

When the adhesive layer is attached to the surface of a product such as glass, the adhesive layer imparts adhesion and enhances visibility by eliminating an air layer, thereby imparting heat insulation and light resistance against ultraviolet rays.

The adhesive layer may include an adhesive resin and a curing agent. The binder resin is not particularly limited as long as it is a resin that does not yellow due to ultraviolet rays and has excellent dispersibility of the ultraviolet absorber. For example, the binder resin may be a polyester resin, an acrylic resin, an alkyd resin, an amino resin, or the like. The binder resin may be used alone, or two or more kinds of copolymers or mixtures thereof may be used. Among them, acrylic resins having excellent optical properties, weather resistance, adhesion to substrates, and the like are preferably used.

The curing agent is not particularly limited as long as it can cure the binder resin. Specifically, it may be one or more selected from the group consisting of an isocyanate curing agent, an epoxy curing agent and an aziridine curing agent which do not yellow by ultraviolet rays. And, the content of the curing agent may be 0.2 to 0.5 weight percent, 0.3 to 0.45 weight percent, or 0.35 to 0.45 weight percent, relative to the total weight of the adhesive layer. When the amount is within the above range, the adhesive strength is reduced, and the durability is advantageously prevented from being lowered in a heat-resistant and moisture-resistant environment.

The adhesive layer contains a dye or a pigment, and can realize a color in a visible light region. Specifically, the above-mentioned adhesive layer may contain a pigment dispersion, and the kind of pigment or pigment dispersion used herein is exemplified above. The content of the above pigment dispersion may be 1 to 30 weight percent, 5 to 20 weight percent, 0.1 to 10 weight percent, or 0.2 to 5 weight percent, relative to the total weight of the above tie layer or the tie layer composition used to prepare the same. When within the above range, it is advantageous to realize colors in the entire visible light region.

In addition, the adhesive layer may further include additives such as an antioxidant, a light stabilizer, a photoinitiator, and the like. For example, the photoinitiator may be one or more selected from the group consisting of benzophenones (benzophenones), thioxanthones (thioxanthones), α -hydroxyketones (α -hydroxy ketones), ketones (ketones), phenylglyoxalates (phenylglyoxalates), and allylphosphine oxides (acryl phosphine oxides).

The adhesive layer is used to prevent glass from scattering due to damage, and the adhesive layer may have an adhesive force of 10N/inch or more, specifically, 10N/inch to 30N/inch. When the amount is within the above range, it is advantageous to obtain a sufficient scattering prevention effect, and in the case of a process failure, it is advantageous to perform a re-processing for recycling of glass.

In order to suppress the extrudability caused by the process and the foreign matter, the adhesive layer has a glass transition temperature of-40 ℃ or higher, and specifically, may have a glass transition temperature of-40 ℃ to-15 ℃ or-30 ℃ to-15 ℃.

The thickness of the above adhesive layer may be 10 μm to 30 μm, 15 μm to 25 μm, 15 μm to 20 μm, or 15 μm to 17 μm. When the content is within the above range, it is advantageous to prevent the occurrence of defects due to pressing and maintain the adhesion.

Patterned layer

The pattern layer may be a layer formed with a pattern, and the design may be realized by a specific pattern or a specific character.

For example, a prism, lens, hemispherical lens pattern is imparted to the surface of the above-mentioned pattern layer, and a special effect is exhibited by additionally imparting refraction and reflection phenomena of light. Specifically, the pattern layer may include a prism layer or a lens layer in a single layer or a double layer.

After the polymer resin composition is injection molded in a mold, a desired pattern may be formed on the pattern layer by Ultraviolet (UV) curing. For example, the pattern layer may include one or more polymer resins selected from urethane acrylic oligomers, amine monomers, and carboxyl monomers.

Also, the thickness of the pattern layer may be 10 μm to 20 μm, specifically 10 μm to 17 μm or 15 μm to 17 μm.

Printing layer

The above-mentioned printed layer includes a material blocking light, and thus reflection efficiency can be further improved. Thus, the printed layer may have a function of blocking light transmission to the rear. The printed layer may include desired patterns, sheets, patterns, colors, textures, and the like according to the marks.

For example, FIG. 4 is a photograph flake illustrating that only a pure reflection color is realized at a flake having a characteristic of mainly reflecting a wavelength of 650nm using a black band. As shown in the drawing, a plurality of colors can be realized by representing different reflection colors according to a viewing angle, and when other colors than black are applied, a plurality of colors can be realized.

The thickness of the above-mentioned printed layer may be 10 μm to 50 μm, specifically 15 μm to 20 μm.

Primer layer

The sheet of the present invention may further comprise a primer layer.

For example, the sheet may further include a primer layer between the base layer and the pattern layer.

The primer layer may realize a color in a visible light region, or may improve a bonding force with an adjacent layer.

The primer layer may include one or more selected from a thermosetting resin, an Ultraviolet (UV) curable resin, and specifically, may include a urethane resin, an acrylic resin, and the like.

The primer layer may contain a dye or pigment for adjusting color. For example, the primer layer may include an acrylic resin or a urethane resin and a dye or a pigment.

Specifically, the above-mentioned primer layer may contain a pigment dispersion, and the kind of the pigment or the pigment dispersion used herein is exemplified above.

The content of the above pigment dispersion may be 1 to 30 weight percent, 5 to 20 weight percent, 0.1 to 10 weight percent, or 0.2 to 8 weight percent, relative to the total weight of the above primer layer or the primer layer composition for preparing the same. When within the above range, it is advantageous to realize colors in the entire visible light region.

The primer layer may be formed by a micro gravure coating method, a slot die coating method, or the like.

The thickness of the above primer layer may be 2 μm to 10 μm, and specifically, may have a thickness of 3 μm to 6 μm.

Reflective layer

The sheet of the present invention may further include a reflective layer for maximizing reflection efficiency or for imparting a metallic texture. For example, the sheet may further include a reflective layer having a metallic texture deposited between the pattern layer and the printed layer.

The reflective layer may be a layer deposited with an inorganic material, and specifically may include one or more inorganic materials selected from niobium (Nb), silicon (Si), titanium (Ti), silver (Ag), and tin (Sn). The reflective layer may be formed of one or more inorganic substances by non-conductive vacuum plating (NCVM).

The reflective layer has not only a reflective effect but also a metallic luster effect due to all colors of inorganic substances and the like. The reflective layer may function as a planarization layer for reducing a height difference of the pattern layer, or may include an additional planarization layer in addition to the reflective layer.

Mobile device

The mobile device provided by the invention can comprise: a cover made of glass or transparent plastic material; and the sheet for preventing scattering and decoration is attached to the cover. The mobile device can be a smart phone or a tablet computer.

The cover to which the sheet of the present invention is attached can exhibit a stereoscopic color according to a viewing angle.

Fig. 2 and 3 are views of a conventional product and a cover to which the sheet of the present invention is attached, viewed from the front (a) and the oblique angle (b), respectively, and compared with each other.

As shown in fig. 2, the prior art products (left side) all showed unchanged white color according to viewing angle, whereas the sheet of the present invention (right side) showed white color from the front and light pink color from the oblique angle.

As shown in fig. 3, the conventional product (left side) shows a red color which is unchanged depending on the viewing angle, whereas the sheet (right side) of the present invention shows a red color from the front and a green color from the oblique angle.

Three-dimensional color coating film

The base material layer and the three-dimensional color coating layer constituting the three-dimensional color coating film may have the same structure and characteristics as those described in the above description of the sheet.

Specifically, the content of the chiral dopant in the stereoscopic color coating layer may be 3 to 5.5 parts by weight based on 100 parts by weight of the nematic liquid crystal component.

When the stereoscopic color coating film is attached to a glass substrate after being stretched and left at 85 ℃ for 72 hours, the minimum stretching ratio at which cracks are generated in the stereoscopic color coating layer may be more than 3%, specifically more than 5%.

And, the wavelength of the reflected light may be 450nm to 750nm with respect to the light perpendicularly incident on the front surface of the stereoscopic color coating film.

Also, the stereoscopic color coating layer may satisfy the following formula (1):

λ＝n×p×cos[sin^-1(sinα/n)]...(1)

Preparation of three-dimensional color coating film

The above-mentioned three-dimensional color coating film is prepared by forming a three-dimensional color coating layer over a base material layer.

The stereoscopic color coating may be formed by wet coating (wet coating). Specifically, the above-mentioned three-dimensional color coating layer can be formed by applying, drying, and curing a coating liquid containing a nematic liquid crystal component, a chiral dopant, a solvent, a photoinitiator, and the like over a base material layer.

First, a nematic liquid crystal component, a chiral dopant, a photoinitiator, an additive, and the like are mixed in a solvent, heated at a temperature lower than an isotropic phase (isotropic phase), sufficiently dissolved, and then cooled at normal temperature for use. In this case, methyl ethyl ketone, toluene, cyclohexanone, or the like can be used as the solvent. Considering that the nematic liquid crystal component has a reactive group at its end, a small amount of the photoinitiator added to the coating liquid is preferable.

In the above coating, not only a general roll coater or a reverse coater but also a slit die coater (blade coater) or the like can be used. When coating, additional shear is required during the coating process in order to align the cholesteric liquid crystal polymer molecules.

The substrate layer for coating may be a polymer film uniaxially or biaxially stretched. The surface of the substrate layer may be rubbed (rubbed) prior to coating, thereby allowing the cholesteric liquid crystal polymer to be better oriented by heating after coating. Alternatively, after coating the surface of the substrate sheet with an alignment film of polyimide type, more effective alignment can be achieved by rubbing the surface.

After coating, the coating can be dried by passing through a drying tunnel at a temperature of about 50 ℃ to 110 ℃, in which case the orientation of the cholesteric liquid crystal polymer can be achieved simultaneously. The time for staying in the drying channel may be 10 seconds to 5 minutes, and the length of the drying channel and the process speed may be appropriately adjusted in consideration of the desired alignment time according to the kind of the cholesteric liquid crystal polymer. The air flow during drying is preferably laminar (laminar flow), whereas turbulent (turbulent flow) causes opaque areas or scattering in the coating due to the influence of orientation, and is therefore preferably avoided.

After drying, the coating can be prepared by irradiating ultraviolet light having a wavelength of 350nm to 400nm at about 500mJ/cm²To 2000mJ/cm²Is irradiated to cure the coating.

Modes for carrying out the invention

Preferred embodiments of the present invention will be described below by way of specific experimental examples. However, the following examples are only for illustrating the present invention, and the scope of the present invention is not limited thereto.

Experimental example 1: measurement of reflection wavelength-variation in amount of chiral dopant added

The reflection wavelength was measured as a function of the amount of the chiral dopant added.

For this purpose, a coating composition is first prepared by mixing the following ingredients. In this case, the coating composition was prepared such that the content of the chiral dopant was 0.5 parts by weight at intervals of 0.5 parts by weight each time to 5 parts by weight with respect to 100 parts by weight of the nematic liquid crystal component.

-nematic liquid crystal composition: 100 parts by weight of LC242 from BASF corporation

-chiral dopant: LC756 by BASF corporation, 3.5 to 5 parts by weight

-a photoinitiator: IRGACURE 819, 6.24 parts by weight from Ciba Specialty Chemicals

-an antioxidant: irganox 1010 from BASF corporation, 1.1 parts by weight

-a solvent: methyl Ethyl Ketone/toluene (1: 1), 40 weight percent solids is suitable

An optical PET film (TU 94 of SKC) as a base material layer having a thickness of 50 μm was wiped once in one direction with a wiper. The coating composition was applied to the surface of the above substrate layer using a bar coater (#6bar) to form a 2.5 μm coating layer and dried in an oven at a temperature of 70 ℃ for 2 minutes to orient. Subsequently, the coating is irradiated with 1J/CM by metallic mercury or the like²The amount of ultraviolet light to ultraviolet cure the coating.

Finally, with respect to the obtained film sample, a transmission spectrum and a reflection spectrum in a wavelength band of 350nm to 750nm were measured using a spectrometer (CM-3700A of MINOLTA).

As shown in fig. 6, it was confirmed that the reflection peak wavelength increases proportionally with the increase in the addition amount of the chiral dopant, and the transmission peak is inversely proportional to the reflection peak. It can be seen that the film of the present invention can easily adjust the reflection color by adjusting the addition amount of the chiral dopant.

Experimental example 2: reflectance measurement-thickness variation of the coating

The reflectance was measured as a function of the thickness of the coating.

For this purpose, a coating composition is first prepared by mixing the following ingredients. In this case, the coating compositions were prepared separately at intervals of 5 weight percent each time starting from 20 weight percent of the solid content until it became 45 weight percent.

-chiral dopant: LC756, 4 parts by weight from BASF

-an antioxidant: rganox1010 from BASF corporation, 1.1 parts by weight

-a solvent: methyl ethyl ketone/toluene (1: 1), 40 weight percent solids (to minimize experimental variation, the amount of solids was adjusted by increasing the amount of solvent in a 45% solids solution.)

An optical PET film (TU 94 of SKC) as a base material layer having a thickness of 50 μm was wiped once in one direction with a wiper. The coating composition was applied to the surface of the above substrate layer using a bar coater (#6bar) to form a coating layer of 1.5 μm to 3 μm and was dried in an oven at a temperature of 70 ℃ for 2 minutes to orient. Subsequently, the coating is irradiated with 1J/CM by metallic mercury or the like²The amount of ultraviolet light to ultraviolet cure the coating.

Finally, with respect to the obtained film sample, a reflectance spectrum in a wavelength band of 350nm to 750nm and a reflectance in 650 nm.

Fig. 7 is a graph showing changes in thickness and reflectance of a coating layer according to the solid content of a coating composition. Fig. 8 is a graph showing a change in reflection spectrum according to the solid content of the coating composition. As shown in fig. 7, it was confirmed that the solid content of the coating composition was in direct proportion to the thickness of the coating layer. As shown in fig. 7 and 8, the reflectance ratio gradually increases as the solid content of the coating composition (or the thickness of the coating layer) increases, and thus it is understood that the reflectance can be easily adjusted by adjusting the thickness of the coating layer. However, the reflectance hardly increases in the solid content of about 30 weight percent or more (or the thickness of about 2.24 μm or more).

Experimental example 3: evaluation of crack Generation

In order to evaluate cracks due to stretching, a three-dimensional color coating film (thickness of base layer: 50 μm, thickness of coating layer: 2 μm) was prepared in the same manner as described above.

Referring to part (a) of fig. 9, the three-dimensional color coating film is cut to length (L)₀)100mm by width (W)25.4mm, thereby preparing a three-dimensional color coating film test piece 201 of the example.

Referring to part (b) of fig. 9, the test piece 201 is stretched in the longitudinal direction by a universal testing machine (uts, AGS-X model manufactured by SHIMADZU corporation). In this case, the stretching ratio is calculated by the following formula. Elongation (%) - (L-L)₀)/L₀X 100 (wherein, L₀The initial length of the test piece, and L the post-stretching length of the test sheet).

Referring to part (c) of FIG. 9, the test piece 201 was attached to a flat glass substrate 21 having a length of 50 mm. times.50 mm in width in a stretched state, and left at 80 ℃ for 72 hours. Subsequently, the surface of the three-dimensional color coating layer of the test piece 201 was observed with a microscope (1500 magnifications) to confirm whether or not cracks were generated.

As a comparative example, a test was conducted on an inorganic deposition film in which an inorganic deposition layer was formed on a PET film by sputtering in the same manner as described above.

As shown in fig. 10, in the case of stretching 1% with respect to the initial length, no cracks were generated in the films of the examples and comparative examples. As shown in fig. 11, when the film was stretched 3% of the initial length, cracks were generated in the inorganic vapor deposited film of the comparative example in the direction perpendicular to the stretching direction, but cracks were not generated in the three-dimensional color coating film of the example. In addition, even when the film was stretched 5% of the initial length, no cracks were generated in the three-dimensional color coating film of the example.

Thus, when applied to a cover having a curved edge such as a smart phone, the conventional inorganic deposition film mainly used for the prevention of scattering and decoration may be deformed to cause cracks, and thus, it is inevitably necessary to minimize the thickness of the inorganic deposition layer.

In contrast, since the stereoscopic color coating film according to the embodiment of the present invention is prepared by wet-coating an organic material, cracks are not generated even in the case of deformation and can be applied to bending, and the reflectance can be improved by increasing the thickness.

Experimental example 4: evaluation of three-dimensional color realization

And forming the three-dimensional color coating layer above the base material layer by the preparation method. And then, a primer layer, a pattern layer, a reflecting layer and a printing layer are sequentially formed on the surface of the substrate layer, and an adhesive layer is formed on the surface of the three-dimensional color coating layer, so that the three-dimensional color coating layer is a sheet for preventing flying and decorating. In this case, a lens pattern for refracting and reflecting colors is formed on the pattern layer by adding a dye to the primer layer to adjust the color again. And, form the reflecting layer and give the metal feel by evaporating the silver behind the above-mentioned pattern layer, apply the black printed layer to obstruct the surplus light reflected from transmitting to the rear on the outermost surface. Next, the adhesive layer of the sheet for scattering prevention and decoration is attached to the glass cover having the bent edge.

Fig. 12 is a view of a sample of the multi-colored sheet for scattering prevention and decoration attached to the glass cover prepared in the above-described manner. As shown in fig. 12, a sheet having various reflection colors and imparting a metallic texture can be prepared according to the present invention and is suitable for a glass cover or the like. And, the primer layer is applied with dyes of various colors to realize composite color, like the second sample on the right, when the primer layer is applied with a dark color dye, the phenomenon that the reflected color is covered due to strong reflection is prevented by properly adjusting the thickness of the stereoscopic color coating, so that the color of the primer layer can be matched.

Fig. 13 shows the reflected color of the rightmost sample in fig. 12 as a function of inclination. As shown in fig. 13, it was confirmed that the color of the sample observed from the front was red, and gradually appeared green with the inclination of the observation angle. Also, a portion adapted to the curved edge of the glass cover is relatively bright and shows a different color from a portion adapted to the flat surface, and thus, differentiation from the existing product can be obtained by giving a bright point on the design level.

Claims

1. A sheet for scattering prevention and decoration, characterized in that,

the method comprises the following steps:

a substrate layer;

the stereoscopic colored coating is formed above the base material layer; and

an adhesive layer formed above the stereoscopic color coating layer,

2. The sheet according to claim 1, wherein the chiral dopant is contained in an amount of 2 to 10 parts by weight based on 100 parts by weight of the nematic liquid crystal component.

3. The sheet according to claim 1, wherein the minimum elongation at which the three-dimensional color coating cracks is greater than 3% when the sheet is attached to a glass substrate after stretching and left at a temperature of 85 ℃ for 72 hours.

4. The sheet according to claim 1, wherein the nematic liquid crystal component comprises at least one of the compounds of the following chemical formulae 1 to 6:

chemical formula 1:

chemical formula 2:

chemical formula 3:

chemical formula 4:

chemical formula 5:

chemical formula 6:

5. the sheet of claim 1, wherein the chiral dopant comprises at least one compound of the following formulae 7 to 10:

chemical formula 7

Chemical formula 8

Chemical formula 9

Chemical formula 10

6. The sheet according to claim 1, wherein when a change of 5 degrees or more is caused with respect to an observation angle of the sheet, a change of a x value of a reflected color based on the CIE Lab color system is 5 or more.

7. The sheeting of claim 1,

the above sheet further comprises:

a pattern layer disposed below the base material layer; and

a printing layer disposed below the pattern layer,

the pattern layer includes a prism layer or a lens layer in a single layer or a double layer,

the printed layer has a function of blocking light from transmitting to the rear.

8. The sheet according to claim 7, further comprising a primer layer between the base material layer and the pattern layer, wherein the primer layer contains an acrylic or urethane resin, and a dye or a pigment.

9. The sheet of claim 7, further comprising a metallic reflective layer deposited between the pattern layer and the printed layer.

10. A mobile device, comprising:

a cover made of glass or transparent plastic material; and

the sheeting of claim 1 attached to said cover.

11. The mobile device of claim 10, wherein the mobile device is a smart phone or a tablet computer.

12. A three-dimensional color coating film characterized in that,

the method comprises the following steps:

a substrate layer; and

a three-dimensional color coating layer formed above the substrate layer,

13. The stereoscopic color coating film according to claim 12, wherein the chiral dopant is contained in an amount of 3 to 5.5 parts by weight based on 100 parts by weight of the nematic liquid crystal component.

14. The stereoscopic colored coating film according to claim 12, wherein a minimum elongation at which the stereoscopic colored coating layer cracks is more than 3% when the stereoscopic colored coating film is attached to a glass substrate after stretching and left at a temperature of 85 ℃ for 72 hours.

15. The stereoscopic color coating film according to claim 12, wherein the wavelength of the reflected light is 450nm to 750nm with respect to the light perpendicularly incident on the front surface of the stereoscopic color coating film.

16. The stereoscopic color coating film according to claim 12, wherein the stereoscopic color coating layer satisfies the following formula (1):

λ＝n×p×cos[sin^-1(sinα/n)]...(1)，

wherein n is the average refractive index of the three-dimensional color coating layer, p is the pitch of the period of the cholesteric liquid crystal polymer molecular arrangement, α is the incident angle of incident light, and λ is the wavelength of reflected light.