KR20140126818A - Optical sheet - Google Patents

Optical sheet Download PDF

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Publication number
KR20140126818A
KR20140126818A KR1020130044339A KR20130044339A KR20140126818A KR 20140126818 A KR20140126818 A KR 20140126818A KR 1020130044339 A KR1020130044339 A KR 1020130044339A KR 20130044339 A KR20130044339 A KR 20130044339A KR 20140126818 A KR20140126818 A KR 20140126818A
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KR
South Korea
Prior art keywords
layer
beads
optical sheet
light
transmissive
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Application number
KR1020130044339A
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Korean (ko)
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KR102030616B1 (en
Inventor
박지민
김봉건
이준용
오종민
Original Assignee
미래나노텍(주)
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Priority to KR1020130044339A priority Critical patent/KR102030616B1/en
Publication of KR20140126818A publication Critical patent/KR20140126818A/en
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Publication of KR102030616B1 publication Critical patent/KR102030616B1/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/12—Reflex reflectors
    • G02B5/122—Reflex reflectors cube corner, trihedral or triple reflector type
    • G02B5/124—Reflex reflectors cube corner, trihedral or triple reflector type plural reflecting elements forming part of a unitary plate or sheet
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
    • B29D11/00—Producing optical elements, e.g. lenses or prisms
    • B29D11/00605—Production of reflex reflectors
    • B29D11/00615—Production of reflex reflectors moulded by partially embedding reflective elements, e.g. glass beads, into the surface of a support, e.g. to make prefabricated road markings
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/04—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of organic materials, e.g. plastics
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/12—Reflex reflectors
    • G02B5/126—Reflex reflectors including curved refracting surface
    • G02B5/128—Reflex reflectors including curved refracting surface transparent spheres being embedded in matrix
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/12—Reflex reflectors
    • G02B5/136—Reflex reflectors plural reflecting elements forming part of a unitary body

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Ophthalmology & Optometry (AREA)
  • Mechanical Engineering (AREA)
  • Laminated Bodies (AREA)
  • Optical Elements Other Than Lenses (AREA)

Abstract

The present invention relates to an optical sheet. The optical sheet includes: a transmission layer made of a thermoplastic resin with light-transmitting attributes; a coating layer arranged on the lower surface of the transmission layer; a reflection layer including multiple corner cubes protruding from the lower surface of the coating layer; and an adhesive layer arranged on the lower surface of the reflection layer.

Description

Optical sheet {OPTICAL SHEET}

The present invention relates to a multi-layered optical sheet, and more particularly to a multi-layered retroreflective optical sheet.

The retroreflective optical sheet has a characteristic of redirecting incident light toward its cause. Due to such optical properties, retroreflective sheeting is widely used in various articles.

However, in the case of the conventional retroreflective optical sheet, polycarbonate is used as a material of a layer through which light is transmitted. In the case of such a polycarbonate, there is a problem that the unit price of the material itself is high.

In addition, there is a problem that light loss is high in the process of passing incident light in the step before reaching the reflective element layer, and the UV curing rate is low during the manufacturing process, resulting in low working efficiency.

In order to solve such a problem, the present invention provides an optical sheet which can improve the retroreflectivity by increasing the transmittance of light incident to the step before reflection by the reflective element, improve the UV curing rate during the manufacturing process, The present invention has been made in view of the above problems.

The optical sheet according to an embodiment of the present invention includes a transmissive layer formed of a thermoplastic resin having light transmittance, and a reflective layer having a coating layer disposed on a lower surface of the transmissive layer and a plurality of corner cubes projecting from a lower surface of the coating layer. And an adhesive layer disposed on the lower surface of the substrate.

Here, the transparent layer includes polyethylene terephthalate (PET).

Meanwhile, the coating layer includes a plurality of beads therein.

Further, the plurality of beads are arranged in a misaligned relationship with each other in the vertical direction.

On the other hand, an overlay layer including an acrylic resin may be further provided on the transmissive layer.

At this time, the overlay layer includes polymethylmethacrylate (PMMA).

The diameter of the beads is substantially 1 to 10 mu m.

According to the optical sheet of the present invention, the following effects are realized.

First, the light incident on the optical sheet reduces the loss in the layered structure inside the sheet to a minimum, thereby improving the transmittance, thereby improving the retroreflectivity.

Second, front angle reflection performance is improved due to reduction of optical loss.

Third, the luminance ratio is increased.

Fourth, in the process of reconditioning the optical sheet, the UV curing rate increases with the increase of the transmittance, and the working efficiency is improved.

Fifth, the optical performance can be further improved without using expensive materials such as polycarbonate, and the manufacturing cost can be reduced.

1 is a cross-sectional view of an optical sheet according to an embodiment of the present invention.
2 is an exploded sectional view of some layers of the optical sheet of Fig.
3 is a view of a corner cube of an optical sheet according to the present invention.

Hereinafter, the present invention will be described in detail with reference to the drawings. The embodiments shown in the drawings of the present invention may be shown in enlarged sizes of certain parts for the sake of understanding. Therefore, the proportions of the sizes of the components are not necessarily limited to the drawings of the present invention.

In the present invention, the upper side indicates the light source direction and the lower side indicates the opposite direction of the light source. That is, the direction from the upper side to the lower side corresponds to the incidence progress path of the light, and the direction from the lower side to the upper side corresponds to the outgoing progress path of the light.

FIG. 1 is a cross-sectional view of an optical sheet according to an embodiment of the present invention. Referring to FIG. 1, an optical sheet 1 according to an embodiment of the present invention includes a transmissive layer 20 having a light- Layer (10).

Here, the overlay layer 10 is a layer formed of a film-like acrylic resin composition and has a thickness of 10-200 micrometers, preferably 25-150 micrometers, and more preferably 30-100 micrometers. When the thickness of the overlay layer 10 made of such an acrylic resin composition is less than 10 micrometers, the layer is easily affected by ultraviolet rays. When the thickness is more than 200 micrometers, the retroreflective performance is lowered or the impact resistance of the sheet is lowered .

The light transmittance of the overlay layer 10 is 85% or more, preferably 90% or more. When the light transmittance of the overlay layer 10 is less than 85%, the retroreflective performance also deteriorates. In particular, the overlay layer 10 may comprise, for example, polymethylmethacrylate (PMMA).

A reflective layer 30 is disposed on the lower surface of the transmissive layer 20 and the reflective layer 30 is formed on the lower surface of the transmissive layer 20 and on the lower surface of the transmissive layer 20, And has a plurality of corner cubes (34) which are disposed and protrude from such a lower surface. The concrete shape of the corner cube 34 will be described later with reference to Fig.

The transmissive layer 20 is typically formed as a light transmissive polymeric material including, for example, polyethylene terephthalate (PET). Coating layer 32 and corner cube 34 may also typically comprise a light-transmitting polymeric material, such as polyethylene terephthalate (PET).

This means that the polymer can transmit at least 70% of the intensity of light incident on the polymer at a given wavelength. More preferably, the polymer used in the optical sheet of the present invention has a light transmittance of 80% or more, and more preferably 90% or more. This permeability corresponds to better performance than using polycarbonate as the permeable layer.

If the retroreflective sheeting is employed in applications other than traffic safety, such as an advertising display, the light transmission may be 5 to 10%.

Meanwhile, the transmissive layer 20 may include a colorant if necessary. The coloring agent to be added to the permeable layer may be added to the permeable layer so that one or more kinds of the coloring agent are easily dissolved together with the material of the permeable layer. The amount of the colorant to be added is not particularly limited and may be added according to the required color tone, and ultraviolet absorbing material is not particularly limited. When a colorant is used in the overlay layer 10, the same material as the colorant used in the overlay layer 10, Can be added.

On the other hand, the coating layer 32 is disposed on the lower surface, that is, the back surface, of the transparent layer 20 formed of polyethylene terephthalate. Here, a plurality of beads 36 (FIG. 2) are disposed in the layer of the coating layer 32. The diameter of the beads 36 is substantially 1 占 퐉 to 10 占 퐉.

A corner cube 34 for controlling the optical path is disposed on the lower surface of the coating layer 32 including a plurality of beads 36 therein. Here, the coating layer 32 and the corner cube 34 may be integrally formed.

In one embodiment of the present invention, the height of the corner cube 34 may be, for example, 20 to 500 micrometers, and more preferably 35 to 100 micrometers.

The embodiment shown in Figure 1 has a reflective layer 30 comprising a single transmissive layer 20 and a single coating and a layer of corner cubes but may also have at least one layer of transmissive and reflective layers repetitively have.

The corner cube 34 may be at least partially attached to the adhesive layer 40 under the corner cube 34 so that a sealing space is formed between the corner cube 34 and the corner cube 34. [

Although not shown in the drawing, the corner cubes and the adhesive layer 40 may be separately formed on each of the corner cubes 34, for example, three corner cubes 34 on the cross section so as to form a sealing space covering the plurality of corner cubes. A sealing protrusion may be formed between the first and second sealing portions. In this case, since the adhesive layer 40 and the corner cube 34 are attached by the protruding sealing protrusions, a hollow sealing space is formed between the adhesive layer 40 and the corner cube 34. Here, the sealing space forms an air layer for improving the retroreflectivity and forms an air interface.

On the other hand, a regular reflection coating (not shown) such as a metal coating can be selectively disposed on the slope of the corner cube 34 to promote retroreflection.

The metal coating may be applied by known techniques such as depositing or chemically depositing a metal such as aluminum, silver or nickel. Alternatively, a primer layer (not shown) may be applied to the sloped surface of the corner cube 34 to facilitate adhesion of the metal coating.

A PET layer 50 is disposed below the adhesive layer 40 disposed on the lower surface of the corner cube 34 and an adhesive layer 60 and a liner layer 70 are sequentially formed on the lower side of the PET layer 50 .

The PET layer 50 comprises polyethylene terephthalate, more specifically a white PET layer, having a thickness of, for example, about 23 micrometers.

In addition, liner layer 70 illustratively includes polypropylene, which has a thickness of, for example, about 75 micrometers.

The adhesive layer 40, the PET layer 50, the bonding layer 60 and the liner layer 70 are fixed to the overlay layer 10, the transmissive layer 20 and the reflective layer 30, . Specifically, the retroreflective optical sheet is provided to protect the retroreflective optical sheet from physical or optical damage, such as contamination or breakage, deterioration due to light or heat, depending on the use purpose and use environment, The material of the layers for fixing the structure is not particularly limited.

1, the reflection layer 30 and the PET layer 50 are shown to be bonded by the adhesive layer 40, but the bonding method thereof is also not particularly limited. Therefore, the method can be adhered by a known hot-melt resin bonding method, a thermosetting resin bonding method, an ultraviolet ray hardening resin bonding method, an electron beam effect resin bonding method, or various methods from the viewpoint of maintaining the shape of a reflective layer, .

2 is a view showing a cross section of the transmissive layer 20 and the reflective layer 30 in the multilayer structure of the optical sheet 1 shown in Fig.

2, a plurality of the beads 36 included in the coating layer 32 attached to the back surface of the transmissive layer 20 among the reflective layers 30 disposed on the lower surface of the transmissive layer 20, (Misaligned) with respect to each other. That is, the plurality of beads 36 are not arranged in layers in the vertical direction so as to be evenly distributed in the coating layer 32.

Therefore, it is preferable that the horizontal distance d1 between the centers of the individual beads 36 be half the diameter d2 of the individual beads, that is, two or more times the radius of the individual beads 36. [ Since the horizontal distance d1 between the centers of the individual beads is formed to be larger than the diameter d2 of the individual beads, the beads are not overlapped with each other in the vertical direction to prevent the occurrence of beads, .

Thus, the beads 42 are arranged to be shifted from each other when seen in the vertical direction, and are exposed to the light introduced in the upward direction, and are not overlapped with each other, Reflection performance is formed.

Rather than the beads being completely aligned in the up-and-down direction, the beads are arranged to be offset from each other in the up-and-down direction, so that the beads arranged in the lower direction contribute to the control of the light path. Alternatively, the beads may be arranged in a single layer in a horizontal direction with no difference in height.

Here, it is preferable that the plurality of beads 36 are formed into a circular sphere made of a glass material. This is because the circular shape has the best performance in order to uniformly compensate the side incident angle at all azimuth angles.

On the surface of the bead 36, a reflective coated surface 38 on which a metal such as aluminum, silver, nickel, or the like is deposited is formed. In addition, since the thickness of the coating layer 32 is about 30 micrometers, the diameter of the beads 36 included in the coating layer 32 is preferably 1 to 10 micrometers.

If the thickness of the coating layer 32 becomes thicker or thinner, the diameter of the bead can be changed accordingly.

On the other hand, the density of the volume occupied by the total sum of the individual beads 36 in the coating layer 32 (i.e., the sum of the total bead volumes from the volume of the entire adhesive layer) may be about 50% to about 80%. If the bulk density of the beads is less than 50%, there is a problem that the beads are too thin and the incidence of the side incident angle is lowered.

On the other hand, when the bulk density of the beads 36 exceeds 80%, there is a problem that the adhesion of the coating layer 32, in which the beads 36 are contained, . Therefore, it is preferable that the bulk density of the beads is about 50% to about 80% in order to maintain adhesiveness of the adhesive layer while maintaining the side incident angle compensating performance by the beads.

On the other hand, the beads preferably have a refractive index of 1.6 or more.

1 and 2, the light having entered from the upper side passes through the overlay layer 10, the transmissive layer 20 formed of a material including polyethylene terephthalate, and then passes through the coating layer 32 on the backside of the transmissive layer .

A part of the light passing through the coating layer 32 is changed to an optical path by the reflection coating surface 38 of the bead 36 formed in the coating layer 32 so that the overall refractive index is increased

Thereafter, the light is reflected by the first inclined surface 35a and the second inclined surface 35b disposed obliquely opposite to each other in the corner cube 34 protruding from the lower surface of the coating layer 32. Depending on the incidence angle of incident light, Is reflected by the first inclined surface 24b and the second inclined surface 24b and is emitted back.

At this time, since the transmissive layer 20 is formed of polyethylene terephthalate exhibiting optical characteristics of high transmittance, light loss is remarkably reduced compared with the case where the transmissive layer is formed of polycarbonate, And the retroreflectivity increases.

3 is a view of a corner cube of an optical sheet according to the present invention. 3 is a bottom view of the bottom surface of the reflective layer 30 of FIG.

As shown in Fig. 3, each corner cube 37 has a triangular prism shape (triangular pyramid shape) having three exposed slopes 39 formed by inclined bus lines 35. As shown in Fig. The slopes may be substantially perpendicular to each other, and the vertex of the prism (the point at which the three sloping buses meet) is aligned perpendicular to the center of the base.

The sizes of the tapered prism shapes may all be unified, but are not limited thereto, and the sizes of the tapered prisms may be used in combination.

The angle between the slopes 39 is the same for each corner cube in the array and can be about 90 degrees, but is not necessarily limited thereto. Thus, the plurality of corner cubes 22 can provide a wide angle retroreflection in a plurality of observation planes.

The corner cube 37 is not limited to the shape described above, and may be in the form of a triangular pyramid, a quadrangular pyramid, a quadrangular pyramid, or a hemispherical shape.

The corner cube 37 may be formed in various ways. A heat transfer method in which a metal mold forming mold and a resin sheet formed in a concave shape in which a triangular pyramid is inverted in general is heated and attached to a belt or a roll to press it, a cast rolling process in which a resin is placed in a mold, And the like can be used. If considering the cost, the productivity, and the environmental problem, the thermal transfer method is preferable.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. will be. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

1: optical sheet 10: overlay layer
20: transmission layer 30: sealing layer
32: Binder layer 34: Corner cube
40: adhesive layer 50: PET layer
60: bonding layer 70: liner layer

Claims (7)

A transparent layer made of a thermoplastic resin having light transmittance
A reflective layer having a coating layer disposed on a lower surface of the transmissive layer and a plurality of corner cubes projecting from a lower surface of the coating layer,
And an adhesive layer disposed on a lower surface of the reflective layer. The method according to claim 1,
Wherein the transmissive layer comprises poly (ethylene terephthalate) (PET). The method according to claim 1,
Wherein the coating layer comprises a plurality of beads inside. The method of claim 3,
Wherein the plurality of beads are arranged in a state of being misaligned with each other in the vertical direction. The method according to claim 1,
And an overlay layer including an acrylic resin is further provided on the transmissive layer. 6. The method of claim 5,
Wherein the overlay layer comprises polymethylmethacrylate (PMMA). The method of claim 3,
Wherein the diameter of the beads is substantially 1 to 10 占 퐉.
KR1020130044339A 2013-04-22 2013-04-22 Retro-reflection optical sheet KR102030616B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
KR1020130044339A KR102030616B1 (en) 2013-04-22 2013-04-22 Retro-reflection optical sheet

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Application Number Priority Date Filing Date Title
KR1020130044339A KR102030616B1 (en) 2013-04-22 2013-04-22 Retro-reflection optical sheet

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KR20140126818A true KR20140126818A (en) 2014-11-03
KR102030616B1 KR102030616B1 (en) 2019-10-11

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH09504238A (en) * 1993-09-10 1997-04-28 リフレキサイト・コーポレーション Fireproof retroreflective structure
JPH09504622A (en) * 1993-10-20 1997-05-06 ミネソタ マイニング アンド マニュファクチャリング カンパニー Flexible cube corner retroreflective sheet material
JP2004507787A (en) * 2000-08-30 2004-03-11 スリーエム　イノベイティブ　プロパティズ　カンパニー Graphic-based structure, retroreflective graphic article manufactured from the structure, and method of manufacturing the same
WO2009133876A1 (en) * 2008-04-30 2009-11-05 共同印刷株式会社 Retroreflector label sheet and article to which retroreflector label sheet is bonded
KR20120098986A (en) * 2012-08-22 2012-09-06 코오롱인더스트리 주식회사 Optical sheet

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH09504238A (en) * 1993-09-10 1997-04-28 リフレキサイト・コーポレーション Fireproof retroreflective structure
JPH09504622A (en) * 1993-10-20 1997-05-06 ミネソタ マイニング アンド マニュファクチャリング カンパニー Flexible cube corner retroreflective sheet material
JP2004507787A (en) * 2000-08-30 2004-03-11 スリーエム　イノベイティブ　プロパティズ　カンパニー Graphic-based structure, retroreflective graphic article manufactured from the structure, and method of manufacturing the same
WO2009133876A1 (en) * 2008-04-30 2009-11-05 共同印刷株式会社 Retroreflector label sheet and article to which retroreflector label sheet is bonded
KR20120098986A (en) * 2012-08-22 2012-09-06 코오롱인더스트리 주식회사 Optical sheet

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