KR20230055156A - Composition for light-shielding film and light-shielding film using the same - Google Patents

Abstract

The purpose of the present invention is to provide a composition for a light-shielding film having low blackness and reflectance and a light-shielding film made therefrom. According to the present invention, the composition for a light-shielding film comprises carbon-based particles, a thermosetting binder resin, a dispersant, polymer beads, and a solvent, wherein the carbon-based particle is a reduced graphene oxide (rGO) particle, a graphene nano platelet (GNP) particle, or a mixture thereof and the polymer bead is at least one selected from a group of consisting of poly(butyl methylacrylate) (PBMA), polymethyl methacrylate (PMMA), and polymethyl silsesquioxane (PMSQ).

Description

Composition for light-shielding film and light-shielding film using the same {Composition for light-shielding film and light-shielding film using the same}

The present invention relates to a light-shielding film that can be used as a spacer or washer of a camera module and a coating solution composition for the same, and more particularly, includes graphene particles and polymer beads to reduce blackness, glossiness, and reflectance. It relates to a light-shielding film and a composition thereof.

Recently, a light-shielding film is applied as a spacer or washer for a camera to suppress a flare phenomenon caused by internal light in a camera module used in a smartphone or the like. These shading films are made by applying a special shading solution to PET film. Essential elements of shading films for camera lenses include low gloss of the coated surface, low reflectance and black color for shading, and lenses and films. In order to prevent static electricity between cells, it is necessary to implement electrical characteristics.

The structure of the currently released light-shielding film for camera modules is composed of a coated structure by applying a composition containing an inorganic lubricant such as carbon black and silica to a synthetic resin film, as described in, for example, Korean Patent Registration No. 10-1145947. However, it still needs improvement in terms of blackness, glossiness, reflectance, and electrical properties.

An object of the present invention is to provide a composition for a light-shielding film having low blackness and low reflectance and a light-shielding film made therefrom.

In order to achieve the above object, in the present invention, carbon-based particles, a thermosetting binder resin, a dispersant, a polymer bead, and a solvent are included, and the carbon-based particles are rGO (reduced graphene oxide) particles, GNP (graphene nano platelet) particles, or These are particles mixed, and the polymer beads are one or more types selected from the group consisting of Poly(butyl methylacrylate) (PBMA), polymethyl methacrylate (PMMA), and polymethyl silsesquioxane (PMSQ). A composition for a light-shielding film can be provided.

In addition, in the composition for a light-shielding film provided by the present invention, the rGO (reduced graphene oxide) or GNP (graphene nano platelet) particles may have an oxygen content of less than 5% by weight and a length/thickness ratio of 100 or more in a plate-like structure. there is.

In addition, in the composition for light-shielding film provided by the present invention, the crystallinity of the rGO (reduced graphene oxide) or GNP (graphene nano platelet) particles is in the range of 0.4 to 1.0, and the crystallinity is the I _G / I _D ratio using Raman spectrum. (Here, I _G is the peak intensity of the graphene component and I _D is the peak intensity of the defect).

In addition, in the composition for a light-shielding film provided in the present invention, the polymer beads have a refractive index (refractive index of 1.4 to 1.5), and D ₅₀ may be in the range of 0.1 to 10 μm when analyzed with a laser scattering type particle size analyzer.

Further, in the composition for a light-shielding film provided by the present invention, in the light-shielding film composition, the carbon-based particles are 0.5 to 3% by weight, the polymer beads are 0.1 to 20% by weight, and the thermosetting binder resin is 1 to 20% by weight. , The dispersant may be in the range of 0.5 to 10% by weight, and the rest may consist of a solvent.

On the other hand, in the present invention, as a light-shielding film made by applying the above-described composition for a light-shielding film to a film, it is possible to provide a light-shielding film having a blackness (L*) of 20 or less and a reflectance of 4.0 or less.

Through the composition for shading film obtained through the present invention, it is possible to obtain a shading film having low blackness, glossiness and reflectance, and through this shading film, a flare phenomenon is prevented even with a film of low thickness in a camera module. there will be no

In describing the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. In addition, when a certain part 'includes' a certain component, this means that it may further include other components without excluding other components unless otherwise stated.

In the present invention, a carbon-based particle, a thermosetting binder resin, a dispersant, a polymer bead, and a solvent are included, and the carbon-based particle is a reduced graphene oxide (rGO) particle, a graphene nano platelet (GNP) particle, or a mixture thereof, and the polymer The bead may provide a composition for a light-shielding film of at least one kind selected from the group consisting of PBMA (Poly (butyl methylacrylate), PMMA (polymethyl methacrylate), and PMSQ (Polymethyl silsesquioxane).

As described above, it is important for the light-shielding film applied to a camera lens or the like to have low gloss, low reflectance, black color for light-shielding, and electrical properties for preventing static electricity. To this end, in the present invention, polymer beads are included as additives for low gloss and reflectance while including carbon-based particles for blackness and electrical properties.

In particular, the carbon-based particles may be rGO (reduced graphene oxide) particles, GNP (graphene nano platelet) particles, or a mixture thereof. By using these rGO and/or GNP in the film composition, the blackness of the final film is lowered. electrical properties can be imparted.

Carbon-based particles, such as rGO or GNP, have an oxygen content of less than 5% by weight and a plate-like structure with a length/thickness ratio of 100 or more. When the ratio of length/thickness is less than 100 in a plate-like shape, the contact area between particles is reduced, resulting in poor electrical properties of the final film.

In addition, the carbon-based particles rGO or GNP preferably have crystallinity (I _G / _ID ratio when measured by Raman spectrum) in the range of 0.4 to 1.0.

Crystallinity can be expressed through a Raman spectrum, where I _G is the peak intensity of a graphene component and I _D indicates the peak intensity of a defect. The crystallinity of the graphene particles can be represented through this ratio, and in the present invention, it is preferable to use rGO or GNP having such a crystallinity in the range of 0.4 to 1.0.

The crystallinity of rGO or GNP, which is a graphene material prepared by exfoliating graphite through a chemical or physical process, may be lowered as defects occur in the C-C bond structure of graphene. If the degree of crystallinity is 0.4 or less, it may be difficult to implement electrical and optical properties of the graphene material because there are so many defects. On the other hand, if the crystallinity is too high and is higher than 1.0, the graphene material has the physical properties of graphite, and it is difficult to disperse in the composition due to the lack of functional groups on the graphene surface, which can make it difficult to implement electrical and optical properties in the final film. .

A polymer bead may be used as an additive in the composition for a light shielding film according to the present invention, and the polymer bead may be at least one selected from the group consisting of poly(butyl methylacrylate) (PBMA), polymethyl methacrylate (PMMA), and polymethyl silsesquioxane (PMSQ). The inventors found that the light-shielding effect in the final film can be increased when these polymer beads are used together with rGO or GNP, which are carbon-based particles, as additives for light-shielding, and included these additives and rGO or GNP together in the composition. .

In particular, PMMA (Ploy (methyl methacrylate)), an acrylic resin, is spherical and has a wide variety of particle sizes already commercialized and easy to obtain, and has already been verified in many fields, making it possible to manufacture film compositions through products of various standards. . PBMA (Poly (butyl methylacrylate) and PMSQ (Polymethyl silsesquioxane) are similarly advantageous for application of film compositions because they can have products of various particle sizes, stable chemical resistance, and refractive index in the required range.

The above-described polymer beads have a refractive index (refractive index of 1.4 to 1.5), and D ₅₀ may be in the range of 0.1 to 10 μm when analyzed with a laser scattering type particle size analyzer.

When the refractive index is 1.5 or more, the antireflection performance is not sufficient, and optical properties may be deteriorated, and polymer beads with a refractive index of 1.4 or less may have difficulty in miscibility with the composition.

In addition, the polymer beads have a particle size of 0.1 to 10 μm based on D ₅₀ when analyzed with a laser scattering type particle size analyzer, where D ₅₀ refers to the particle size when the cumulative percentage of the particles reaches 50%. If the particle size of the polymer particles is less than 0.1 μm based on D ₅₀ , handling is difficult due to severe aggregation between the polymer particles and dispersion in the composition becomes difficult due to the increased specific surface area. On the other hand, if the thickness exceeds 10 μm, the roughness of the final film may increase, and a desired light blocking effect may not be obtained.

On the other hand, in the composition for light-shielding film in the present invention, the carbon-based particles are 0.5 to 3% by weight, the polymer beads are 0.1 to 20% by weight, the thermosetting binder resin is 1 to 20% by weight, and the dispersant is in the range of 0.5 to 10% by weight. can be

Carbon-based particles such as rGO, GNP, or a combination thereof are preferably included in an amount of 0.5 to 3% by weight in the composition. If it is smaller than this range, the electrical properties and blackness of the film cannot be adjusted to the desired level, and if it is larger than this range, the electrical properties and blackness of the film cannot be adjusted to the desired level. Since the amount of additives for light blocking is reduced, desired gloss cannot be achieved.

Polymer beads, which are additives, may be included in an amount of 0.1 to 20% by weight. If the amount is less than this range, the light blocking effect cannot be obtained, and if it is large, the amount of carbon-based particles, which are other solid materials, may be reduced, so that the properties in terms of electrical conductivity and blackness may be reduced. it might not be good

Polyacrylate, polyurethane, polyester, polyalkoxylate, polyether, polyvinyl chloride, etc. may be used as the thermosetting binder resin, and if the binder resin is less than 1% by weight, sufficient bonding strength between particles of the solid phase may be imparted. If it is too much and exceeds 20% by weight, the amount of graphite-based particles or polymer particles as additives is reduced by that much, so that desired physical properties cannot be obtained.

Polyurethane-based, fatty acid-based, CPT-based, phosphoric acid ester-based resins, etc. containing an acid value or amine value may be used as the dispersant. If it is less than 0.5% by weight, the solid material cannot be smoothly dispersed, and if it exceeds 10% by weight, it is rather Dispersion effect is reduced.

The rest of the composition is composed of a solvent, and the solvent may be ketone-based (MEK, MIBK), acetate-based (n-buthyl acetate, ethyl cellosolve acetate, butyl cellosolve acetate), toluene, or the like.

A light-shielding film is prepared by applying the composition for a light-shielding film to a polymer film. The light-shielding film produced through this may have a blackness (L*) of 20 or less and a reflectance of 4.0 or less.

Such a light-shielding film can have excellent characteristics without a flare phenomenon even at a low coating thickness.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings in order to fully understand the present invention.

The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art, and the following examples may be modified in many different forms, and the scope of the present invention It is not limited to the examples below. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the spirit of the invention to those skilled in the art.

[Production Example]

40% of polyacrylic binder (Aekyung Chemical) 30wt%, 49~62wt% of solvent mixed with MEK and MIBK 8:2, 3~7wt% of dispersant 1 (acrylic) and dispersant 2 (urethane) in a 1:1 ratio in a container and then mixed in a mixer for 30 minutes to prepare a vehicle for the coating solution.

Different amounts of PMSQ or PMMA beads of various sizes were put into the prepared vehicle, mixed in a mixer for 10 minutes, then rGO powder (Angstron) was added by content, and mixed in a mixer for 30 minutes to prepare a mixed solution.

The stirred mixed solution was mixed with zirconia beads and then dispersed for 60 minutes using a paint shaker to prepare a graphene dispersion coating solution.

After coating the prepared coating solution on a black PET film and drying in an oven at 100 ° C for 3 minutes, the coating film was measured with a spectrophotometer (Konica Minolta CM-5), a micro gloss meter (BYK AG 4563), and a sheet resistance (Sinco ST4) meter. The physical properties of were analyzed.

coating composition bookbinder dispersant solvent additive carbon-based particles Content (wt%) Content (wt%) Content (wt%) type Content (wt%) type Content (wt%) Example 1 30 3 60 PMSQ (5㎛) 5 rGO 2 Example 2 30 3 60 PBMA (5㎛) 5 rGO 2 Example 3 30 3 60 PMMA (5㎛) 5 rGO 2 Example 4 30 3 60 PMMA (10㎛) 5 rGO 2 Example 5 30 3 60 PMMA (1㎛) 5 rGO 2 Example 6 30 3 64 PMMA (5㎛) One rGO 2 Example 7 30 3 55 PMMA (5㎛) 10 rGO 2 Example 8 30 One 63.5 PMMA (5㎛) 5 rGO 0.5 Example 9 30 2 62 PMMA (5㎛) 5 rGO One Example 10 30 5 57 PMMA (5㎛) 5 rGO 3 Comparative Example 1 30 3 50 - - carbon black 15 Comparative Example 2 30 3 51 silica One carbon black 15 Comparative Example 3 30 3 65 - - rGO 2 Comparative Example 4 30 3 64 silica One rGO 2 Comparative Example 5 30 7 54 PMMA (5㎛) 5 rGO 4

As additives in Examples 1 to 10, polymer beads having a refractive index in the range of 1.4 to 1.5 were added according to size and material, and rGO (Angstron) was used as the carbon-based particles. In Comparative Examples 2 and 4, inorganic silica particles were used as additives, and in Comparative Examples 1 and 2, carbon black was used as carbon-based particles.

After coating the coating composition having the composition shown in the table above on a black PET film, a film was prepared by oven drying at 100 ° C. for 3 minutes, and a spectroscopic colorimeter (CM-5 by Konica Minolta) and a micro glossmeter (BYK) were used for the film. AG 4563) and sheet resistance (Sinco ST4) were used to analyze the physical properties of the coating film. The results are shown in Table 2 below.

Properties black too Reflectance (600nm) Polish Sheet Resistance (Log R) Example 1 14.7 1.75 0.4 4.6 Example 2 15.1 1.75 0.4 4.6 Example 3 14.5 1.71 0.4 4.6 Example 4 14.9 1.73 0.4 4.6 Example 5 15.5 2.13 0.4 4.6 Example 6 17.5 2.55 0.5 4.6 Example 7 14.5 1.76 0.4 4.9 Example 8 29 4.95 8 8.9 Example 9 17.6 2.6 0.5 4.9 Example 10 14.0~15.1 1.69 to 1.8 0.4 3 Comparative Example 1 25.02 5.21 90 5.0 Comparative Example 2 27.2 4.99 2.5 5.1 Comparative Example 3 25.96 4.34 One 4.4 Comparative Example 4 27.03 4.09 0.4 4.6 Comparative Example 5 uncoated

In Examples 1 to 3, blackness, reflectance, and glossiness were similar in the same size and addition amount for each type of polymer beads, and in particular, PMMA showed the best blackness. As a result of evaluation with different PMMA sizes of 1, 5, and 10 μm, blackness and reflectance were the best in the case of 5 μm. As the addition amount of PMMA decreased, the blackness and reflectance tended to increase, and as the addition amount increased, the blackness and reflectance improved, but the roughness of the coated surface increased and the electrical properties tended to decrease. In the example in which rGO was added to the carbon-based particles, the blackness and sheet resistance increased as the addition amount decreased, but if the addition amount was too large, the coating surface became non-uniform due to the increase in the viscosity of the coating solution.

Claims (6)

Including carbon-based particles, thermosetting binder resin, dispersant, polymer beads and solvent,
The carbon-based particles are reduced graphene oxide (rGO) particles, graphene nano platelet (GNP) particles, or a mixture thereof,
The polymer bead is at least one kind selected from the group consisting of PBMA (Poly (butyl methylacrylate), PMMA (polymethyl methacrylate) and PMSQ (Polymethyl silsesquioxane), a composition for a light-shielding film. According to claim 1,
The rGO (reduced graphene oxide) or GNP (graphene nano platelet) particles have an oxygen content of less than 5% by weight and a plate-like structure with a length / thickness ratio of 100 or more. According to claim 1,
The crystallinity of the rGO (reduced graphene oxide) or GNP (graphene nano platelet) particles ranges from 0.4 to 1.0, and the crystallinity is the I _G / I _D ratio using a Raman spectrum (where I _G is the peak intensity of the graphene component and I _D is the peak intensity of defects), a composition for a light-shielding film. According to claim 1,
The polymer beads have a refractive index (refractive index of 1.4 to 1.5), and D ₅₀ is in the range of 0.1 to 10 μm when analyzed with a laser scattering type particle size analyzer. According to claim 1,
In the light-shielding film composition, the carbon-based particles are 0.5 to 3% by weight, the polymer beads are 0.1 to 20% by weight, the thermosetting binder resin is 1 to 20% by weight, the dispersant is in the range of 0.5 to 10% by weight, and the rest is a solvent. Consisting of, a composition for a light-shielding film. A light-shielding film made by applying the composition for a light-shielding film according to any one of claims 1 to 4 on a film, having a blackness (L*) of 20 or less and a reflectance of 4.0 or less.