TWI619615B - Encapsulating method for optical device with multi-layered structure - Google Patents

Abstract

The present invention relates to a method for sealing a multilayer structure of an optical element. More specifically, by having a multilayer structure in which a polysilicon nitride layer is formed on or under a silicon layer as another layer, an outgassing optical element can be reduced. A multilayer structure sealing method and an optical element containing the multilayer structure sealing material manufactured through the method.

Description

Method for sealing multilayer structure of optical element Field of invention

The present invention relates to a method for sealing a multilayer structure of an optical element. In more detail, it minimizes out-gas by forming an additional polysilicon nitrogen layer above and / or below the silicon layer. , And a multilayer structure sealing method for an optical element capable of improving refractive index, light transmittance, hardness, and barrier properties against moisture, and an optical element including a multilayer structure sealing material manufactured through this. In addition, the present invention relates to a method for forming a silicon layer on the surface of a thin film substrate and forming another polysilicon nitrogen layer on the upper and / or lower portion of the silicon layer, thereby improving the refractive index, light transmittance, hardness, and moisture content. A method for producing a protective film having barrier properties and the like, and a protective film produced by the aforementioned method.

Background of the invention

Because the organic substances contained in optical elements such as OLED and LCD are very fragile to atmospheric oxygen or water vapor, if they are exposed to oxygen or water vapor, it will cause a reduction in output or early performance. Therefore, methods have been developed to protect the aforementioned elements with metal and glass to extend the life of the elements, but metal generally has insufficient transparency and glass has flexibility (flexibility) shortcomings.

Therefore, a bendable transparent barrier film and a sealing material composition have been developed, which are used to seal other optical elements including thin, light, and flexible OLEDs.

As a result of this, Japanese Patent Laid-Open No. 2009-146924 describes a technique of dispersing polysilicon nitrogen and an inorganic substance in a plurality of organic resin layers. However, the organic resin layer is generally represented by epoxy and acrylic resins. However, during operation, for optical elements that exhibit high junction temperature, yellowing may occur during long-term exposure. Possibility of discoloration. When using polysilazane-dispersed materials to form it, there are various side effects caused by the outgassing of silicon nitrogen.

Also, U.S. Patent Application No. 20020113241 describes a technique for minimizing outgassing by subjecting a polysilicon nitrogen film to an oxidation treatment. However, when polysilicon nitrogen is oxidized, the main factor related to the crosslink density of polysilicon nitrogen in the body during oxidation -Si-N-Si-bond has been replaced with -Si-O-Si- The cross-linking density decreases, and in this case, the barrier performance and the adhesion force may decrease.

In addition, Japanese Patent Laid-Open No. 08-236274 describes a technology in which a polysilicon nitride film is configured as a single film. However, when the film is configured as a single film, the barrier performance is lower than that in the case of a multilayer structure. The thicker the coating thickness of the device, the more it will cause outgassing.

On the other hand, for existing protective films for displays such as smart phones, the surface hardness is low, durability is reduced, fingerprint resistance, scratch resistance, pollution resistance, heat resistance, light transmittance and haze characteristics Inferior issues, and In order to solve this problem, it is necessary to form multiple functional layers with more than 3 layers and form individual functions, but it is quite inconvenient in the process and difficult to apply, and there will be a problem of reduced productivity.

Summary of invention

In order to solve the foregoing problems, an object of the present invention is to provide a multilayer structure sealing method of an optical element that can reduce outgassing by forming a polysilicon nitrogen layer as an additional layer above or below a silicon layer, And an optical element including a multilayer structure sealing material manufactured through the multilayer structure.

In addition, an object of the present invention is to provide a method for manufacturing a protective film which can form a silicon layer and another polysilicon nitrogen layer on the surface of a film substrate, and can simultaneously improve the refractive index, light transmittance, hardness, and barrier properties against moisture. , And a protective film made by the aforementioned method.

To achieve the foregoing object, the present invention provides a method for sealing a multilayer structure of an optical element, which is characterized in that in the method for sealing an optical element, a silicon layer-polysilicon layer or a polysilicon layer-silicon layer is sequentially used as a sealing material. It is formed on the surface of the optical element to be sealed.

In addition, the present invention provides an optical element, which is a multi-layer sealing material that is sealed by the aforementioned sealing method and includes a silicon layer-polysilicon layer or a polysilicon layer-silicon layer.

The present invention also includes an optical device including the optical element.

In addition, in the method for manufacturing a protective film, the present invention provides a method for manufacturing a protective film, which is characterized in that a silicon layer-polysilicon nitride layer or a polysilicon nitrogen layer-silicon layer is sequentially formed on a surface of a thin film substrate.

The present invention also provides a protective film manufactured by the aforementioned method.

The sealing method of the present invention and the optical element of the present invention have a multilayer structure in which a polysilicon nitrogen layer is formed on the upper part and / or lower part of the silicon layer as another layer. The refractive index difference is compensated (Refractive Index matching), which can increase the light extraction efficiency. Not only that, by minimizing out-gas, it can form a transparent film with uniform internal / surface, hardness and moisture Or oxygen barrier properties. Therefore, the sealing method of the present invention can be effectively applied to the sealing of various optical elements, especially the sealing of high specifications or thick films, and can also be effectively applied to the protective film of a display.

1‧‧‧ lens

2‧‧‧sealing material

3‧‧‧Gold wire

4‧‧‧ reflector

5‧‧‧Die Attach Adhesive

6‧‧‧Lead Frame

FIG. 1 is a schematic cross-sectional view of a sealing material having a single-layer structure according to a comparative example.

Fig. 2 is a schematic cross-sectional view of a sealing material having a multilayer structure according to the present invention.

Fig. 3 is a schematic cross-sectional view of a sealing material having a multilayer structure according to the present invention.

Fig. 4 is a schematic cross-sectional view of a sealing material having a multilayer structure according to the present invention.

Fig. 5 ... A cross-sectional view of an optical element using a sealing material according to the present invention.

Forms used to implement the invention

Hereinafter, the present invention will be described in detail.

The method for sealing an optical element of the present invention is characterized in that in the method for sealing an optical element, a silicon layer-polysilicon layer or a polysilicon layer-silicon layer is sequentially formed on the surface of the optical element to be sealed as a sealing material. .

In the present invention, the aforementioned silicon layer may be coated and formed with a composition for forming a silicon layer on a substrate to be coated and formed with a layer. The composition for forming a silicon layer may also be a known composition. The composition for forming a silicon layer is preferably a polyhedral siloxane oligomer (POSS) containing the following chemical formula 1-1 or 1-2:

In the above formula, R is independently a compound of the following chemical formula 2-1 or 2-2:

In the above formula, R ₁ to R ₆ are each independently hydrogen, an alkyl group having 1 to 20 carbon atoms, an alkenyl group or an aryl group having 6 to 50 carbon atoms, and hydrogen, methyl, ethyl, vinyl, or phenyl Preferably, more preferably: R ₁ is hydrogen or methyl, R ₂ is methyl or phenyl, R ₃ is hydrogen, methyl or phenyl, R ₄ is hydrogen, methyl or vinyl, and R ₅ is methyl R ₆ is methyl, ethyl or phenyl; Ra is independently hydrogen or chlorine; z is an integer of 3 to 20, preferably an integer of 5 to 20; a and b are respectively Independently, it is an integer from 0 to 20, and a + b is an integer from 3 to 20, and M, Ma, and Mb are independently methyl or phenyl.

The compound of the aforementioned chemical formula 1-1 or 1-2 is centered on the compound of the following chemical formula 2-1, and the compound of the following chemical formula 2-2, the compound of the following chemical formula 2-3, or the compound of the following chemical formula 2-4 Compounds and 2-5 compounds are used as reactants and synthesized by polymerization in distilled water:

In the above formula, R ₁ to R ₆ , z, a, and b are as defined above; Ra and R ₇ are each independently hydrogen or chlorine; and x and y are each independently an integer from 1 to 100.

In the present invention, the functional group R of the aforementioned polyhedral siloxane oligomer does not need to undergo a process of dissolving in an organic solvent, and still has sufficient compatibility with the siloxane resin, not only here, but also in the oligomer or copolymer In this case, the inclusion of crosslinkable sites can improve the crosslinking density and mechanical properties of the resin composition, and also contribute to the improvement of gas barrier properties.

In the present invention, the polyhedral siloxane oligomer may be used in an amount of 0.01 to 30% by weight, and preferably in an amount of 0.05 to 15% by weight relative to the composition for forming a silicon layer. The compatibility of the siloxane resin is reduced.

In the present invention, the composition for forming a silicon layer may contain, in addition to the polyhedral siloxane oligomer, a commonly used siloxane resin, a crosslinked resin, a silane coupling agent, a catalyst, and a reaction delay. Agent.

According to one aspect of the present invention, the aforementioned composition may contain 1 to 30% by weight of a polyhedral siloxane oligomer, 20 to 90% by weight of a silicone resin, and 1 to 30% by weight of a crosslinked resin with respect to the entire composition. , Silane coupling agent 0.05 to 20% by weight, catalyst 1 to 3000 ppm and reaction delay agent 1 to 1000 ppm.

Examples of the silicone resin usable in the present invention include polymethylvinylsiloxane, poly (methylphenyl) hydrosiloxane, poly (methylphenyl) siloxane, and poly (benzene). (Vinyl vinyl)-(methyl vinyl) semi-siloxane copolymer, PDV-1635 from Gelest, etc. Examples of the crosslinking resin include a semi-siloxane copolymer, phenyl hydrogen Examples of silane coupling agents include methacrylate-based cyclosiloxanes and the like. As the catalyst, there is a platinum catalyst, and examples of the reaction delaying agent include ethynyltrimethylsilane or ethynyltriethylsilane, but it is not limited thereto, and may contain one or more of these materials.

In the present invention, the polysilicon nitrogen layer may be produced by coating a composition to be coated on a substrate to be coated and hardening it, and the composition for forming a polysilicon nitrogen layer may include the following An organic polysilicon nitrogen or a silicon nitrogen-based oligomer of Chemical Formula 3 is preferred. At this time, it is more helpful to remove the out-gas phenomenon that reduces the barrier characteristics of the optical element.

In the above formula, R _x and R _y are each independently an alkyl group, alkenyl group, or aryl group having 6 to 50 carbon atoms, preferably methyl, ethyl, vinyl, or phenyl, and more Preferably, R _x is methyl, ethyl, or phenyl, and R _y is methyl, ethyl, or vinyl; m and n are each independently an integer of 1 to 20, and m + n is 2 to 21 at this time. The content of the silicon nitrogen compound in the composition for forming a polysilicon nitrogen layer can be arbitrarily adjusted. For example, based on the content of the composition at 100% by weight, it can be used alone or a known solvent can be used.

The composition for forming a polysilicon nitrogen layer is preferably a modified polysilicon nitrogen compound further containing the following Chemical Formula 4.

[Chemical Formula 4]

In the above formula, Ra is an alkyl group having 1 to 20 carbon atoms or aryl group having 6 to 50 carbon atoms; Rb is a hydrocarbon having 1 to 20 carbon atoms, preferably a hydrocarbon having 1 to 5 carbon atoms; p is 1 to 15 Integer.

The compound of the aforementioned chemical formula 4 can be a solution (solution) including a compound of the following chemical formula 4-1 and a compound of the following chemical formula 4-2, or a compound of the following chemical formula 4-2 and the following chemical formula 4-3. ) Aggregation to synthesize:

In the above formulas, R _c is hydrogen or chloro; R _d, R _e, and R _f are each independently an aryl group of hydrogen, an alkyl group having a carbon number of 1 to 20, or an alkenyl group of 6-50 carbon atoms.

The aforementioned modified polysilicon nitrogen compound can be contained therein in an amount of 1 to 50% by weight of the composition forming the polysilicon nitrogen layer. When it exceeds the foregoing content, the outgassing phenomenon is deepened, and the barrier characteristics are reduced.

In the present invention, regarding the formation of the silicon layer and the polysilicon nitrogen layer, the silicon layer forming composition or the polysilicon nitrogen layer forming composition may be coated on the surface to be sealed, and then silicon may be formed through a hardening step. Layer or polysilicon layer.

The aforementioned coating method is of course optional and used by the operator, and the coating thickness can also be selected by the operator and applied to the thickness of each layer. For example, the silicon layer can be 0.5 to 2000um, preferably 1 to 1000um, and the polysilicon nitrogen layer can be used. It is 0.01 to 1000um, preferably 0.02 to 500um.

Before coating the composition for forming the silicon layer, the composition is preferably a composition that has undergone a pretreatment step.

The aforementioned pre-treatment means that it can be stirred at a temperature of 70 to 120 ° C. for 3 to 24 hours under a pressure of 10 ^-1 Torr or less in a reactor under vacuum conditions and a mixing treatment.

If the polysilicon nitrogen is pretreated in the aforementioned manner, the unreacted monomers of the polysilicon nitrogen material itself and the factors that induce outgassing can be minimized, so the unevenness caused by the sealing layer can be suppressed, and the barrier performance can be reduced. Maximize.

In the present invention, when the aforementioned silicon layer is formed, thermal hardening can be performed at a temperature of 40 to 250 ° C. for 5 minutes to 3 hours. It is better to subdivide the melting and hardening steps into two or more stages, and more preferably, the hardening temperature and hardening time Subdivide to a minimum of 2 The hardening is preferably carried out in stages up to seven stages. For example, a two-stage hardening at a temperature of 100 to 170 ° C and a two-stage hardening at a temperature of 130 to 250 ° C can be divided into two or more stages.

In addition, when the aforementioned polysilicon nitrogen layer is formed, the thermal hardening can be in the range of 30 to 250 5 minutes to 2 hours at a temperature of ℃, it is better to harden by subdividing into 1 to 3 stages of hardening. For example, it can be divided into 1 stage hardening at 30 to 120 ° C and 2 stages hardening at 90 to 170 ° C. And the melting and hardening steps of three stages of hardening at a temperature of 130 to 250 ° C.

If the multi-stage thermal hardening step is performed as described above, the formation of holes in the material itself can be suppressed, and outgassing during the hardening process can be minimized.

In addition, the present invention provides an optical element, which is a multi-layer sealing material that is sealed by the aforementioned sealing method and includes a silicon layer-polysilicon layer or a polysilicon layer-silicon layer. 2 to 4 are schematic cross-sectional views of an optical element including a multilayer sealing material according to the present invention. In FIG. 5, the sealing material 2 can be made of a silicon layer-polysilicon layer, a polysilicon layer-silicon layer, or a polysilicon layer- The silicon layer-polysilicon nitrogen layer, or the silicon layer-polysilicon nitrogen layer 1-polysilicon nitrogen layer 2 is configured.

The optical element of the present invention has a multilayer structure having a silicon layer and another polysilicon nitrogen layer. The optical characteristics such as light transmittance and refractive index and the barrier properties to external gases (water vapor, oxygen, etc.) are very excellent. The adhesive force of the substrate (substrate or silicon layer) is improved, which is very effective for extending the life of the optical element, especially the high-spec optical element containing LED, for example, it can be effectively applied in the field of LED outdoor lighting.

A polysilicon nitrogen layer is formed on the silicon layer and / or using the multilayered optical element sealing material of the present invention manufactured by the aforementioned composition. The lower part, preferably the upper part, compensates for the difference in refractive index (Refractive Index) between the luminescent substance or wafer of the optical element and the atmosphere (for example, the refractive index of the LED is about 2.5 and the refractive index of the atmosphere is 1.0) ( Refractive Index matching), which can increase the light extraction efficiency, so it can also be applied to high-spec optical components using LEDs.

According to the present invention, if a polysilicon nitrogen layer is formed on the upper portion of the silicon layer, The refractive index is 1.0 to 1.6, and if the polysilicon nitrogen layer is formed under the silicon layer, the refractive index is 1.4 to 2.5.

Also, it is different from dispersing polysilicon nitrogen in a silicon composition as a single layer. Manufacturing technology (Figure 1), by forming another polysilicon nitrogen layer, outgassing will not be enclosed inside the silicon layer when the polysilicon nitrogen is hardened, and a sealing film with no holes and uniform and transparent inside and surface of the film can be obtained. Moreover, since two or more films are formed, they have excellent barrier properties against moisture, oxygen, and the like.

The present invention also provides a method for manufacturing a protective film, It is characterized in that a method for manufacturing a protective film of a silicon layer-polysilicon nitrogen layer or a polysilicon nitrogen layer-silicon layer is sequentially formed on the surface of a film substrate, and a protective film manufactured by the foregoing method. Here, the protective film of the present invention is manufactured Among the methods, the method of forming the silicon layer and the polysilicon nitrogen layer may use the aforementioned sealing method, and the film substrate may use a substrate for a well-known protective film. As an example of the aforementioned film substrate, polyester-based films (PET, PES, PEN) or polyolefin-based films (PE, PP) are suitable, and polyester-based films such as PET or PES are particularly suitable for use as optical elements. In addition, the protective film of the present invention may further include an adhesive-type release film on the protective film. Regarding a protective film containing a release film, when the protective film of the present invention is attached to a device to be protected, After the release film is made, the layers are laminated so that the protective film can be attached, which can further facilitate the process.

The protective film of the present invention is made of silicon only on the surface of the film substrate. The formation of the layer and the polysilicon nitrogen layer can also improve the refractive index, light transmittance, hardness, and barrier properties against moisture of the protective film at the same time, and can be effectively used in optical machines or display machines.

In the following, preferred embodiments are proposed for the understanding of the present invention, but The following examples are merely illustrative of the present inventors, and the scope of the present invention is not limited by the following examples.

Synthesis example 1: Synthesis of polyhedral siloxane oligomer (C-POSS)

As a reactant, distilled water was slowly added dropwise to a mixture of tetrasilane benzene POSS and dichloromethylphenylsilane at about 30 ° C under normal pressure and stirred, and then stirred at 50 ° C for about 3 hours to remove the solvent and synthesize Polyhedral siloxane oligomers.

Manufacturing Example 1: Pretreatment of polysilicon nitrogen

As polysilicon nitrogen, HTT-1500 (AZ company) and HTT-1800 (AZ company) were placed in a reactor capable of performing vacuum treatment and mixing treatment, respectively, and the reactor was converted into a vacuum condition (pressure: 10 ^-1 Torr or less), and then stirred at about 50 to 100 ° C for 3 to 24 hours to complete the pretreatment.

Example 1

A resin composition for an optical element sealing material for a multilayer structure was produced based on the composition of Table 1 below.

Specifically, only a specific amount of C-POSS of Synthesis Example 1, the siloxane resin 2, the crosslinked resins 1 and 2, and the silane coupling agent were added and a composition was produced. Compound A, and then adding siloxane resin 1, catalyst and reaction retarder to produce composition B, considering the molar ratio of the components added to composition A and B, using a revolution-rotation vacuum defoamer to manufacture the mixed solution Into a single liquid type.

In addition, as the composition for forming a polysilicon nitrogen layer, pretreated polysilicon nitrogen was used.

Example 2 and Comparative Examples 1-3

According to the composition of Table 1 below, a resin composition for an optical element sealing material for a multilayer structure was produced by the same method as in the foregoing Example 1.

Siloxane resin 1: poly (methylphenyl) siloxane

Siloxane resin 2: poly (phenylvinyl)-(methylvinyl) hemisiloxane copolymer

Crosslinked resin 1: phenylhydrogen silsesquioxane

Crosslinked resin 2: dimethylsilyl phenyl ether

C-POSS: Polyhedral siloxane oligomer produced in the aforementioned Synthesis Example 1

Silane coupling agent: methacrylate functional cyclosiloxane

Catalyst: SIP6830.3 (Gelest)

Reaction delaying agent 1: ethynyltrimethylsilane (Gelest)

Reaction delaying agent 2: ethynyltriethylsilane (Gelest)

Polysilazane 1: Pretreated HTT-1500 (AZ Company)

Polysilazane 2: Pretreated HTT-1800 (AZ Company)

Test example

The resin compositions of the optical element sealing materials for multilayer structures of Examples 1 and 2 and Comparative Examples 1 and 2 were evaluated for their physical properties and performance in the following manner, and the results are shown in Table 2 below.

1) Light transmittance: The aforementioned composition for forming a silicon layer is coated on the surface of upper and lower glass and Teflon frame to have a size of 50 mm × 50 mm × 1 mm, and then at 150 ° C. for 1 hour and After hardening at 170 ° C for 1 hour, a polysilicon nitrogen (PSZ) layer-forming composition having a thickness of about 5um was coated on the upper part, and then hardened at 40 ° C for 30 minutes, 100 ° C for 30 minutes, and 170 ° C for 1 hour. Make test pieces. The ultraviolet light-visible spectrophotometer (Mecasys) was used to measure the individual light transmittance of the five points of the test piece manufactured at a wavelength of 400 to 780 nm, and evaluated from the average value in the obtained wavelength range. Transmittance. At this time, the light transmittance of the silicon single-layer film structure manufactured using the composition of the comparative example is taken as a reference, and the group using the example is shown. Light transmittance of a multilayer structure made of an object.

2) Hardness: on the surface of 20mm × 20mm × 15mm Teflon module After coating the composition for forming a silicon layer, curing at 150 ° C. for 1 hour and 170 ° C. for 1 hour, and then coating the composition for forming a polysilicon nitrogen (PSZ) layer with a thickness of about 5 μm on the top, at 40 ° C. The test piece was hardened at 30 ° C. for 30 minutes at 100 ° C., and at 170 ° C. for 1 hour to produce a test piece, and thereafter measured using a Shore hardness tester.

3) Water vapor transmission rate: on the surface of Teflon module to become After coating the composition for forming a silicon layer in a manner of 50 mm × 50 mm × 1 mm, and curing at 150 ° C. for 1 hour and 170 ° C. for 1 hour, a polysilicon nitrogen (PSZ) layer for forming a thickness of about 5 μm was coated on the upper portion. After the composition, the test piece was hardened at 40 ° C for 30 minutes, 100 ° C for 30 minutes, and 170 ° C for 1 hour. A water vapor transmission rate tester (PERMATRAN-W, MOCON) was used to measure the water vapor transmission rate of the test piece at about 24 hours under a gas environment of 37.8 ° C and 100% RH. The average value is shown below. Table 2.

As shown in Table 2 above, it has a multilayer structure in which a polysilicon nitrogen layer is formed on the upper and / or lower portions of the silicon layer as another layer. The sealing material of the present invention not only has excellent light transmittance and hardness, but also exhibits better water. Vapor transmission rate.

Claims (20)

A method for sealing a multilayer structure of an optical element. In the method for sealing an optical element, a silicon layer-polysilicon layer or a polysilicon layer-silicon layer is used as a sealing material, so that they are sequentially formed on the optical element to be sealed. On the surface, the aforementioned silicon layer is manufactured by coating and hardening a silicon layer-forming composition containing a polyhedral siloxane oligomer (POSS) of the following chemical formula 1-1: In the above formula, R is independently a compound of the following chemical formula 2-1: In the above formula, R ₁ to R ₂ are each independently hydrogen, an alkyl group having 1 to 20 carbon atoms, an alkenyl group or an aryl group having 6 to 50 carbon atoms; Ra is independently hydrogen or chlorine; and z is 3 to 20 An integer; M is independently methyl or phenyl. The multilayer structure sealing method for an optical element according to claim 1, wherein the polyhedral siloxane oligomer of the aforementioned Chemical Formula 1-1 is used in an amount of 1 to 30% by weight based on the composition for forming a silicon layer. The multilayer structure sealing method for an optical element according to claim 1, wherein the aforementioned curing is performed at a temperature of 40 to 250 ° C for 5 minutes to 3 hours. For example, the multilayer structure sealing method for an optical element according to claim 3, wherein the aforementioned hardening is performed in two or more melting and hardening steps. The multilayer structure sealing method of the optical element according to claim 1, wherein the coating of the aforementioned silicon layer is 0.5 to 2000um. The method for sealing a multilayer structure of an optical element according to claim 1, wherein the aforementioned polysilicon nitrogen layer is manufactured by coating and curing a polysilicon nitrogen layer-containing polysilazane layer-forming composition containing the following chemical formula 3: In the above formula, R _x and R _y are each independently an alkyl group having 1 to 20 carbon atoms, an alkenyl group or an aryl group having 6 to 50 carbon atoms; m and n are each independently an integer of 1 to 20, at this time m + n is 2 to 21. The multilayer structure sealing method for an optical element according to claim 6, wherein the composition for forming a polysilicon nitrogen layer contains 1 to 50% by weight of the polysilicon nitrogen shown in the aforementioned chemical formula 3. The method for sealing a multilayer structure of an optical element according to claim 6, wherein the composition for forming a polysilicon nitrogen layer further contains a modified polysilicon nitrogen as shown in the following chemical formula 4: In the above formula, Ra is an alkyl group having 1 to 20 carbons or an aryl group having 6 to 50 carbons; Rb is a hydrocarbon having 1 to 5 carbons; and p is an integer of 1 to 15. The multilayer structure sealing method of the optical element according to claim 6, wherein the composition for forming a polysilicon nitrogen layer is subjected to a pre-stirring at a pressure of 10 ^-1 Torr or lower and a temperature of 70 to 120 ° C for 3 to 24 hours before coating. Treatment and coating. The multilayer structure sealing method for an optical element according to claim 6, wherein the aforementioned curing is performed at a temperature of 30 to 250 ° C for 5 minutes to 2 hours. The multilayer structure sealing method of the optical element according to claim 10, wherein the aforementioned hardening is performed by hardening in 1 to 3 stages. The multilayer structure sealing method of the optical element according to claim 6, wherein the foregoing The coating of the polysilicon nitrogen layer is 0.01 to 1000um. An optical element characterized by being sealed by the sealing method according to any one of claims 1 to 12 and including a sealing material having a multilayer structure. The optical element according to claim 13, wherein the aforementioned optical element has a polysilicon nitride layer formed on the silicon layer. The optical element of claim 13, wherein the refractive index of the aforementioned optical element is 1.0 to 1.6. An optical machine comprising the optical element of claim 13. The optical device of claim 16 is an LED lighting device. A method for manufacturing a protective film. In the method for manufacturing a protective film, a silicon layer-polysilicon nitrogen layer or a polysilicon nitrogen layer-silicon layer is sequentially formed on the surface of a thin film substrate. The foregoing silicon layer will include the following chemical formula: The composition for forming a silicon layer of 1-1 polyhedral siloxane oligomer (POSS) is coated and hardened to produce: In the above formula, R is independently a compound of the following chemical formula 2-1: In the above formula, R ₁ to R ₂ are each independently hydrogen, an alkyl group having 1 to 20 carbon atoms, an alkenyl group or an aryl group having 6 to 50 carbon atoms; Ra is independently hydrogen or chlorine; and z is 3 to 20 An integer; M is independently methyl or phenyl. The method for manufacturing a protective film according to claim 18, wherein the aforementioned polysilicon nitrogen layer is produced by coating and curing a polysilicon nitrogen layer-containing polysilazane layer-forming composition containing the following chemical formula 3: In the above formula, R _x and R _y are each independently an alkyl group having 1 to 20 carbon atoms, an alkenyl group or an aryl group having 6 to 50 carbon atoms; m and n are each independently an integer of 1 to 20, at this time m + n is 2 to 21. A protective film made by the method of claim 18.