KR101229145B1 - Reflection sheet - Google Patents

Abstract

The present invention relates to a reflective sheet, and more particularly, using a cyclic olefin polymer (COP) or a cyclic olefin copolymer (COC) as a base resin and containing fine bubbles having an average particle diameter of 50 μm or less as a base layer. By providing a reflective sheet, it improves weather resistance and dimensional stability, and further forms an ultraviolet ray blocking layer to prevent yellowing, uniformly form a plurality of fine bubbles and optionally include a metal plate to improve reflectance for the backlight unit Sheets can be provided.

Reflective sheet, Cyclic olefin polymer, Weather resistance, Supercritical fluid, Microbubble

Description

Reflection sheet {Reflection sheet}

The present invention relates to a reflective sheet, and more particularly to a reflective sheet for a backlight unit of a liquid crystal display.

Recently, liquid crystal displays, which are used as main components of TVs, desktop computers, notebooks, mobile phones, etc., use a liquid crystal layer of non-light-emitting materials, so a separate light source must be installed, and the side or rear side of the light source reflects the light emitted to the rear part. In order to install the reflective sheet. The reflected light is emitted to the front while passing through a diffusion plate, a light guide plate, a diffusion film, and a brightness improving sheet.

Here, the reflective sheet should have reflectivity to reflect the light of the light source lamp to improve the brightness to the extent that the liquid crystal screen does not flash and concealment so that devices, frames, and the like arranged on the rear surface of the backlight unit are not identified.

Conventionally, as the reflection sheet, a white pigment such as titanium oxide is dispersed in a sheet made of a synthetic resin, a metal deposition film is laminated on the surface, or a bubble is dispersed in order to scatter light in a sheet made of a synthetic resin.

However, when the white pigment is dispersed, the amount of pigment should be increased to suppress the leakage of light to the back side. Since the white pigment absorbs light of a specific wavelength, the amount of the addition increases the light loss and the reflectance is deteriorated. .

In addition, when metal deposition is applied to the surface, there is a problem in that manufacturing cost is high, and since diffuse reflection is difficult to occur, there is a problem that luminance smear occurs even in small distortion of the sheet. In the case of vapor deposition, there is a problem in that high luminance cannot be obtained depending on the type of metal, or weather resistance is insufficient, so that deterioration proceeds quickly, resulting in deterioration of luminance over time.

On the other hand, polyethylene terephthalate (PET) resin is mainly used as the synthetic resin used in the reflective sheet. PET resin is excellent in heat resistance, rigidity and electrical properties, and the ultimate strength is slightly reduced even at high temperature for a long time. It is also a crystalline plastic and therefore has good resistance to oils such as diesel oil. However, due to ester bonds in the molecular chain, molded products are susceptible to change when they are immersed in acids or alkalies at high temperatures and over long periods of time.

Accordingly, the present inventors have confirmed that the present invention can provide a reflective sheet having excellent reflectivity and high weather resistance and dimensional stability, and completed the present invention.

Accordingly, an object of the present invention is to provide a reflective sheet capable of providing excellent weather resistance, dimensional stability, and reflectance.

In order to achieve the above object, the present invention uses a cyclic olefin polymer (COP) or a cyclic olefin copolymer (COC) as a base resin, and includes a reflective sheet containing fine bubbles having an average particle diameter of 50 μm or less. To provide.

The cyclic olefin polymer or copolymer is characterized in that it contains 0.1 to 100% by weight of the cyclic olefin unit based on the total weight of the (co) polymer.

The cyclic olefin polymer or copolymer is characterized in that it comprises a cyclic olefin unit obtained by polymerizing or copolymerizing at least one monomer selected from cyclic olefins represented by the following formulas (1) to (6).

≪ Formula 1 >

<Formula 2>

<Formula 3>

&Lt; Formula 4 >

&Lt; Formula 5 >

(6)

In Chemical Formulas 1 to 6, R ¹ to R ⁸ are the same as or different from each other, and are hydrogen or straight or branched C ₁ to C ₃₀ hydrocarbon radicals, and two or more of R ¹ to R ⁸ are bonded to a ring. May have been done.)

The cyclic olefin polymer or copolymer is bicyclo [2,2,1] hept-2-ene (common name: norbornene), 5-methylbicyclo [2,2,1] -hept-2-ene, 5 , 5-dimethyl-bicyclo [2,2,1] -hept-2-ene, 5-ethyl-bicyclo [2,2,1] -hept-2-ene, 5-butyl-bicyclo [2, 2,1] hept-2-ene, 5-ethylidene-bicyclo [2,2,1] hept-2-ene, 5-hexyl-bicyclo [2,2,1] hept-2-ene, 5 -Octyl-bicyclo [2,2,1] hept-2-ene, 5-octadecyl-bicyclo [2,2,1] hept-2-ene, 5-methylidene-bicyclo [2,2, Cyclic selected from 1] hept-2-ene, 5-vinyl-bicyclo [2,2,1] hept-2-ene and 5-propenyl-bicyclo [2,2,1] hept-2-ene It is characterized by containing an olefin monomer.

The base layer is characterized in that the sunscreen is further formed on one or both sides.

The UV blocking layer is characterized in that it comprises a photocurable resin, a photoinitiator and a light stabilizer in a ratio of 100: 2 ~ 10: 0.1 ~ 2.0.

The photocurable resin is an acrylic resin, characterized in that at least one selected from urethane acrylate, urethane methacrylate, epoxy acrylate, epoxy noblock acrylate, polyester acrylate and polybutadiene acrylate.

The reflective sheet is characterized in that the thickness is 0.3 ~ 1.5㎜.

The UV blocking layer is characterized in that the thickness is 1.0 ~ 5.0㎛.

The base layer is characterized in that the specific gravity is 0.2 ~ 0.8.

The fine bubbles of the base layer is characterized in that formed by the supercritical fluid foam.

The base layer or the UV blocking layer is characterized in that the metal layer is further formed on one surface.

The metal layer is characterized in that formed of one metal selected from aluminum, stainless steel and silver.

The metal layer is characterized in that the thickness is 1.0 ~ 5.0㎛.

Hereinafter, the present invention will be described in more detail.

The reflective sheet of the present invention uses a cyclic olefin polymer (COP) or copolymer (COC) as a base resin as a white synthetic resin that can be foamed.

The cyclic olefin polymer or copolymer is a polymer produced by the polymerization of a cyclic olefin monomer such as norbornene, and has excellent transparency, heat resistance, and chemical resistance, and has low birefringence and water absorption rate as compared with the existing olefin polymer. Therefore, insulating film of semiconductor or TFT-LCD, polarizer protective film, multichip module, integrated circuit (IC), printed circuit board, encapsulant of electronic material or flat panel display Alternatively, the present invention may be used as a low dielectric coating agent, film, and packaging for optics, and may also be used as a material of a plastic substrate for implementing flexible displays.

Polymerization technology of the cyclic olefin polymer or copolymer may include Ring Opening Metathesis Polymerization (ROMP), Ring opening metathesis polymerization followed by hydrogenation (HROMP), copolymerization with ethylene, homopolymerization, and the like. And transition metal catalysts such as Pd-compounds.

The cyclic olefin polymer or copolymer may be a homopolymer or copolymer including a cyclic olefin unit or a copolymer further comprising an acrylic olefin unit, if necessary. Suitable cyclic olefin polymers or copolymers in the present invention contain 0.1 to 100% by weight, preferably 10 to 99% by weight, more preferably 50 to 95% by weight, based on the total weight of the polymer. will be. The cyclic olefinic units of the polymer may be obtained by polymerizing one or more monomers preferably selected from cyclic olefins represented by the following formulas (1) to (6).

In addition to the homopolymer or copolymer obtained from these monomers, the cyclic olefin polymer or copolymer of the present invention includes a ring-opening (co) polymer, an addition (co) polymer, an addition copolymer of the above-described acrylic olefin, or a hydrogenated product thereof. .

&Lt; Formula 1 >

<Formula 2>

<Formula 3>

&Lt; Formula 4 >

&Lt; Formula 5 >

(6)

In Chemical Formulas 1 to 6, R ¹ to R ⁸ are the same as or different from each other, and are hydrogen or straight or branched C ₁ to C ₃₀ hydrocarbon radicals, and two or more of R ¹ to R ⁸ are bonded to a ring. May have been done.)

Specifically, the cyclic olefin monomer or copolymer is bicyclo [2,2,1] hept-2-ene (common name: norbornene), 5-methylbicyclo [2,2,1] -hept-2-ene , 5,5-dimethyl-bicyclo [2,2,1] -hept-2-ene, 5-ethyl-bicyclo [2,2,1] -hept-2-ene, 5-butyl-bicyclo [ 2,2,1] hept-2-ene, 5-ethylidene-bicyclo [2,2,1] hept-2-ene, 5-hexyl-bicyclo [2,2,1] hept-2-ene , 5-octyl-bicyclo [2,2,1] hept-2-ene, 5-octadecyl-bicyclo [2,2,1] hept-2-ene, 5-methylidene-bicyclo [2, 2,1] hept-2-ene, 5-vinyl-bicyclo [2,2,1] hept-2-ene, 5-propenyl-bicyclo [2,2,1] hept-2-ene and the like. Can be mentioned.

If necessary, the cyclic olefin copolymer may contain 0 to 45% by weight of at least one monocyclic olefin unit of formula (7) based on the total weight of the polymer.

&Lt; Formula 7 >

(In said formula, n is an integer of 2-10.)

In addition, if necessary, the cyclic olefin copolymer may contain 0 to 99% by weight of the cyclic olefin unit of the formula (8) based on the total weight of the polymer.

(8)

(Wherein R ⁹ to R ¹² are the same or different hydrogen atoms, C ₁ to C ₈ alkyl radicals or C ₆ to C ₁₄ aryl radicals.)

Compared to the cyclic olefin polymer (COP), the cyclic olefin copolymer (COC) having a single carbon bond in the main chain has a more flexible property.

The fine bubbles preferably have an average particle diameter of 50 µm or less. When the average particle diameter exceeds 50 mu m, the reflectance decreases because incident light penetrates into the interior of the reflective sheet or the number of diffuse reflections at the bubble interface decreases.

On the other hand, it is preferable that the base layer has a specific gravity of 0.2 to 0.8, and if the specific gravity exceeds 0.8, that is, the bubble ratio decreases and other requirements are satisfied, the absorption of light in the portion of the resin which is not foamed or the transparency of the reflecting sheet are required. The light loss due to light transmission caused by the light is increased, so that the reflectance is lowered. If the specific gravity is less than 0.2, the rigidity is clearly lowered, indicating a problem that shape retention is difficult.

In order to form fine bubbles in the present invention, it is preferable to use a foaming technique using a supercritical fluid, and in particular, it is possible to form fine bubbles of 50 μm or less. More preferably, the supercritical fluid used here is a supercritical fluid of N ₂ or CO ₂ .

The base layer of the present invention may further include an inorganic filler, a light stabilizer or an antioxidant, in the case of adding them, after mixing the base resin with a substance to be added using a tumbler mixer and then using a twin screw extruder The pellets are processed into pellets and fed into an extruder.

Examples of the inorganic fillers for increasing the reflectance include barium sulfate, calcium sulfate, magnesium sulfate, barium carbonate, calcium carbonate, magnesium chloride, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, titanium dioxide, alumina, silica, talc, zeolite, and the like. . In particular, it is preferable to use barium sulfate and calcium carbonate which are excellent in dispersibility with resins and optical properties. The inorganic filler for increasing the reflectivity is preferably an average particle diameter of 10㎛ or less, the reason is that when the average particle diameter exceeds 10㎛ exhibits a disadvantage that the surface properties are lowered. On the other hand, it is preferable that the addition amount is 40 weight part or less with respect to 100 weight part of base resins, and when it exceeds 40 weight part, there exists a problem that surface characteristic falls similarly.

In addition, the base layer may further include a UV absorber and a UV stabilizer as a light stabilizer. As the ultraviolet absorber, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4 -n-octoxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, bis (5-benzoyl-4-hydroxy-2- Benzophenone compounds such as methoxyphenyl) methane and 2,2'-dihydroxy-4-methoxybenzophenone, 2-2'-methylenebis [4- (1,1,3,3-tetramethylbutyl -6- (2H-benzotriazol-2-yl) phenol], 2- (2'-hydroxy-5'-methylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'- Benzotriazole-based compounds such as di-tert-butylphenyl) -5-chlorobenzotriazole, etc. The content of the ultraviolet absorber is preferably less than 1% by weight.

In addition to the ultraviolet absorber, it is preferable to supplement the ultraviolet stabilizer in order to suppress deterioration of the resin. A hindered amine stabilizer etc. are mentioned as an ultraviolet stabilizer, As an addition amount, less than 1 weight% is suitable with respect to a base resin.

And an antioxidant may be further included in the base layer. As the antioxidant, primary antioxidants such as hindered phenol derivatives and aromatic amine derivatives are effective, but phosphorus derivatives or sulfur derivatives exhibiting effects on high temperature heat resistance. It is preferable to use the secondary antioxidant of together. The primary antioxidant acts as a radical scavenger to destabilize the polymer by deodorizing free radicals generated in the polymer material, and the secondary antioxidant acts as a peroxide decomposer and acts as a secondary antioxidant. will be. The amount of antioxidant to add is suitably less than 1 weight% with respect to a base resin.

On the other hand, due to the characteristics of the reflective sheet is continuously exposed to light from the light emitting device is inevitable deterioration of optical and mechanical properties due to ultraviolet light, the light stabilizer included in the base layer alone is insufficient to prevent the degradation of the physical properties, and thus In the present invention, a UV blocking layer is formed on one or both surfaces of the base layer of the reflective sheet. The method of forming the UV blocking layer is not particularly limited, but a method of applying the UV blocking layer composition to the surface of the base layer by applying microgravure, gravure, or mayor may be used to irradiate and cure UV rays after drying.

The UV blocking layer composition is characterized in that it comprises a photocurable resin, a photoinitiator and a light stabilizer in a ratio of 100: 2 ~ 10: 0.1 ~ 2.0. When the content of the photoinitiator is included in less than the above range, it may be difficult to cure the photocurable resin, and when included in the content of the photoinitiator exceeding the above range may cause physical property degradation or discoloration of the photocurable resin. In addition, when the content of the light stabilizer is contained less than the above range, it is not possible to obtain appropriate weather resistance by lowering the light resistance, etc., if it is included beyond the above range may cause a decrease in physical properties of the photocurable resin.

The photocurable resin is at least one selected from urethane acrylate, urethane methacrylate, epoxy acrylate, epoxy noblock acrylate, polyester acrylate and polybutadiene acrylate as an acrylic resin.

As the photoinitiator, benzyl dimethyl ketal, benzoin butyl ether, trimethyl benzophenone, alpha-hydroxy ketone and benzophenone can be used.

The light stabilizer used in the UV blocking layer composition is as described in the base layer.

The UV blocking layer has a thickness of 1.0-5.0 μm, and the reflective sheet may have a thickness of 0.3-1.5 mm, preferably 0.5-0.7 mm.

If the thickness of the UV blocking layer is less than 1.0㎛ the UV blocking effect is deteriorated and curing of the photocurable resin may not occur properly, if it exceeds 5.0㎛ it is difficult to fulfill the function of the reflective sheet.

In addition, when the thickness of the reflective sheet is less than 0.3 mm, there is a disadvantage in that it is difficult to handle during post-processing and inferior in shape retention, and the reflectance decreases due to a large amount of light leaking. In addition, when the thickness exceeds 1.5mm, not only the foldability of the reflective sheet is lowered, but also the thickness of the backlight unit is increased, thereby countering the trend of thinning of the liquid crystal display.

A metal layer may be further formed to increase the reflectance of the reflective sheet. The metal layer may be formed on one surface of the base layer or may be formed on the other side of the base layer when the UV blocking layer is formed on one surface of the base layer, and when the UV blocking layer is formed on both sides of the base layer. It may be formed on the other side of the.

As the metal forming the metal layer, one selected from aluminum, stainless steel, and silver is used, and the method of forming the metal layer may use a method such as metal deposition or lamination, and is not particularly limited.

It is preferable that the said metal layer makes the thickness 1.0-5.0 micrometers.

Hereinafter, examples of the present invention will be described in more detail, but the scope of the present invention is not limited to these examples.

&Lt; Example 1 >

0.2 parts by weight of a benzophenone ultraviolet absorber and 0.1 parts by weight of a phenolic antioxidant were added to 100 parts by weight of a norbornene polymer (Zeon, Zeonor 1060R) in an extruder, and melted at 200 ° C. The N ₂ gas in the state was added thereto, and the supercritical fluid and the base resin introduced using a screw were kneaded under the condition of 165 ° C. Thereafter, the supercritical fluid was made into a foamed state immediately before extrusion, and then passed through a compression roll to prepare a reflective sheet.

<Example 2>

In the composition of Example 1, with respect to 100 parts by weight of norbornene polymer (Zeon, Zeonor 1060R), 10 parts by weight of calcium carbonate was added to prepare a reflective sheet in the same manner.

<Example 3>

A reflective sheet was manufactured in the same manner as in Example 1, except that 20 parts by weight of calcium carbonate was added to 100 parts by weight of norbornene polymer (Zeon, Zeonor 1060R).

<Example 4>

To 100 parts by weight of the ethylene-norbornene copolymer (TICONA, ^Topas® 6013) in the extruder, ^{except that} 0.2 parts by weight of benzophenone-based ultraviolet absorber, 0.1 parts by weight of phenolic antioxidant and 10 parts by weight of calcium carbonate were added. A reflective sheet was prepared in the same manner as in Example 1.

<Example 5>

A base layer was manufactured in the same manner as in Example 2, and a UV blocking layer was formed on one surface (lamp direction). As the photocurable resin, 5 parts by weight of a ketone-based photoinitiator (KOLON, KF2121B) and 1 part by weight of a hindered amine light stabilizer were mixed with 100 parts by weight of a urethane acrylate resin composition (KOLON, KF2121A). A barrier layer composition was prepared, coated with microgravure, dried at 100 ° C., and then cured by irradiating ultraviolet rays generated with a mercury lamp for 5 seconds at a light amount of 50 mJ / cm ² to form a 2 μm thick ultraviolet barrier layer.

<Example 6>

In Example 5, the reflective sheet was prepared by laminating aluminum using an acrylic adhesive on a surface opposite to the surface on which the UV blocking layer was formed.

&Lt; Comparative Example 1 &

Except for using a polymethyl methacrylate resin (Lucite, CP81) instead of the norbornene polymer in Example 2 was prepared a reflective sheet in the same manner.

Comparative Example 2

Except for using a chemical foaming method as a method for forming micro-bubbles in Example 2 to provide a reflective sheet in the same manner.

That is, 0.2 parts by weight of a benzophenone ultraviolet absorber, 0.1 part by weight of a phenolic antioxidant and 10 parts by weight of calcium carbonate are added to 100 parts by weight of a norbornene polymer (Zeon, Zeonor 1060R) in a 65 mm tandem extruder at 50 kg / h. After feeding to a 65mm tandem extruder at 50kg / h, and plasticized at 200 ℃ in the first stage extruder (65mm diameter), 5 parts by weight of isobutane as a blowing agent to 100 parts by weight of the resin, The resin temperature was cooled to 150 ° C. in a second stage extruder and passed through the pressing roll and guide roll to obtain a sheet having a thickness of 0.6 mm.

The physical properties of the reflective sheets prepared in Examples and Comparative Examples were measured as follows, and the results are shown in Table 1 below.

(1) bubble average particle diameter

The average particle diameter of the bubble in a base layer was calculated | required by taking the SEM photograph of a cross section, measuring the average particle diameter of the bubble contained in a fixed cross-sectional area, and averaging.

(2) Specific gravity

Specific gravity is measured by the submerged method, and measurement conditions are carried out at a temperature of 23 ° C. and a relative humidity of 65%. The thickness is obtained using a vernier caliper.

(3) reflectance

Reflectance is measured in the wavelength range of 380 ~ 780nm by using a spectrophotometer (UV spectrophotometer, Varian) and reflectance of the wavelength of 550nm as a representative value.

(4) yellowing

Yellowing is a measure of weatherability using the change of yellowness after UV exposure, after 240 hours in a Q-UV accelerated weathering tester equipped with FS-40 313/280 lamp according to ASTM D1925 standard, and then according to ASTM D1003 standard. The amount of change in the YI value before and after exposure is obtained and shown.

(5) Dimensional stability

After the reflective sheet is installed in a 20-inch backlight, it is left at 60 degrees and 75% RH for 4 days, and then the curl phenomenon is confirmed.

(6) foldability

The foldability is marked as good if not broken when the 10 cm ㅧ 10 cm specimen is folded at 90 degrees and bad if broken.

division Bubble particle size (㎛) Sheet thickness
(Μm) importance reflectivity(%) Yellowing Dimensional stability Foldability Example 1 32 600 0.5 89 14.1 Good Good Example 2 30 600 0.5 92 14.2 Good Good Example 3 29 600 0.5 95 14.2 Good Good Example 4 27 600 0.5 92 13.8 Good Good Example 5 30 600 0.5 92 5.8 Good Good Example 6 30 605 0.6 98 5.9 Good Good Comparative Example 1 18 600 0.6 87 2.4 Bad Bad Comparative Example 2 215 600 0.4 72 14.2 Good Good

 As a result of the experiment, in Examples 3 to 6, a reflective sheet having a good high reflectance was obtained, and as the amount of calcium carbonate was increased, a slight reflectance synergistic effect was obtained, and by using a metal having high reflective efficiency on the back, Reflectance could be obtained. In addition, when comparing Examples 1 to 3 without applying the UV blocking layer and Example 5 or Example 6 with the UV blocking layer formed, it can be seen that the reflective sheets of Examples 5 to 6 of the present invention have excellent weather resistance. .

On the other hand, in Comparative Example 2 by applying a general chemical foaming method it can be seen that the size of the bubble particle size is formed relatively large, showing a low reflectance.

In Examples 1 to 6 and Comparative Example 2, the reflective sheet was composed of norbornene polymer, so that the foldability and dimensional stability were excellent. It can be seen that the folding and dimensional stability is not excellent.

As described above, the present invention improves weather resistance and dimensional stability by using a cyclic olefin polymer (COP) or a cyclic olefin copolymer (COC) as a base resin, and further forms a UV blocking layer to prevent yellowing. It is possible to provide a reflective sheet for a backlight unit in which fine bubbles are uniformly formed and optionally provided with a metal plate to improve reflectance.

Claims (14)

As the base layer, cyclic olefin polymer (COP) or cyclic olefin copolymer (COC) is used as the base resin, and contains microbubbles with an average particle diameter of 50 µm or less, The base layer is a reflection sheet, characterized in that the UV blocking layer is further formed on one or both surfaces. The method of claim 1, The cyclic olefin polymer or copolymer is a reflective sheet, characterized in that containing 0.1 to 100% by weight of the cyclic olefin units based on the total weight. 3. The method according to claim 1 or 2, The cyclic olefin polymer or copolymer is a reflective sheet, characterized in that it comprises a cyclic olefin unit obtained by polymerizing or copolymerizing at least one monomer selected from cyclic olefins represented by the following formulas (1) to (6). &Lt; Formula 1 >

<Formula 2>

<Formula 3>

&Lt; Formula 4 >

&Lt; Formula 5 >

(6)

In Chemical Formulas 1 to 6, R ¹ to R ⁸ are the same as or different from each other, and are hydrogen or straight or branched C ₁ to C ₃₀ hydrocarbon radicals, and two or more of R ¹ to R ⁸ are bonded to a ring. May have been done.) 3. The method according to claim 1 or 2, The cyclic olefin polymer or copolymer is bicyclo [2,2,1] hept-2-ene (common name: norbornene), 5-methylbicyclo [2,2,1] -hept-2-ene, 5 , 5-dimethyl-bicyclo [2,2,1] -hept-2-ene, 5-ethyl-bicyclo [2,2,1] -hept-2-ene, 5-butyl-bicyclo [2, 2,1] hept-2-ene, 5-ethylidene-bicyclo [2,2,1] hept-2-ene, 5-hexyl-bicyclo [2,2,1] hept-2-ene, 5 -Octyl-bicyclo [2,2,1] hept-2-ene, 5-octadecyl-bicyclo [2,2,1] hept-2-ene, 5-methylidene-bicyclo [2,2, Cyclic selected from 1] hept-2-ene, 5-vinyl-bicyclo [2,2,1] hept-2-ene and 5-propenyl-bicyclo [2,2,1] hept-2-ene Reflective sheet, characterized in that it comprises an olefin monomer. delete The method of claim 1, The UV blocking layer is a reflective sheet, characterized in that it comprises a photocurable resin, a photoinitiator and a light stabilizer in a ratio of 100: 2 ~ 10: 0.1 ~ 2.0. The method of claim 6, The photocurable resin is an acrylic resin, a reflection sheet, characterized in that at least one selected from urethane acrylate, urethane methacrylate, epoxy acrylate, epoxy noblock acrylate, polyester acrylate and polybutadiene acrylate. The method of claim 1, The reflective sheet is a reflective sheet, characterized in that the thickness is 0.3 ~ 1.5㎜. The method of claim 1, The UV blocking layer is a reflection sheet, characterized in that the thickness is 1.0 ~ 5.0㎛. The method of claim 1, The base layer is a reflection sheet, characterized in that the specific gravity is 0.2 ~ 0.8. The method of claim 1, The microbubble of the base layer is a reflective sheet, characterized in that formed by the supercritical fluid foam. The method of claim 1, The base layer or the UV blocking layer is a reflective sheet, characterized in that the metal layer is further formed on one surface. 13. The method of claim 12, The metal layer is a reflective sheet, characterized in that formed of a metal using one selected from aluminum, stainless steel and silver. 13. The method of claim 12, The metal layer is a reflection sheet, characterized in that the thickness is 1.0 ~ 5.0㎛.