UV-curable protective material composition with excellent flame retardancy and LED display using the same.

Abstract

This invention provides an ultraviolet-curable protective material that is excellent in flame retardancy, optical properties, and durability, making it suitable for application in LED displays and other applications, as well as an LED display using the same. [Solution] The invention comprises an oligomer having a skeleton selected from polyisobutylene and hydrogenated polybutadiene and having a bifunctional acrylic group, an acrylic monomer, and a solid-phase flame retardant containing a photoinitiator and phosphorus, wherein the solid-phase flame retardant has a D90 particle size of 2 to 20 μm, and the phosphorus is present in an amount of 10% by weight or more based on the total weight of the solid-phase flame retardant.

Description

Technical Field

[0001] The present invention relates to an ultraviolet curable protective material having excellent flame retardancy and an LED display using the same. Specifically, it contains a solid flame retardant containing phosphorus, the D90 particle size of the solid flame retardant is 2 to 20 μm, and the phosphorus is contained at 10% by weight or more based on the total weight of the solid flame retardant, thereby having excellent flame retardancy, optical properties, and durability, and relates to an ultraviolet curable protective material composition suitable for application to LED displays and the like.

Background Art

[0002] Since LEDs are sensitive to heat and moisture, when used without appropriate protection, they may deteriorate over time and have a shortened lifespan. Furthermore, when there is a lot of exposure to the external environment, such as in outdoor billboards or portable devices, high durability of the display is required. In particular, since flammable materials are used in LED displays, in the event of a fire, there is a risk of significantly increasing the damage, so it is necessary to apply a protective material with flame retardant performance.

[0003] To date, various techniques have been attempted to impart flame retardant performance to the protective layer of LED displays. However, in the case of halogen-based flame retardants with excellent flame retardancy, the amount used is regulated due to environmental problems, so there is a problem that it is impossible to apply a sufficient amount of halogen-based flame retardants to impart flame retardancy. In the case of non-halogen-based flame retardants, an excessive amount of flame retardant needs to be added to ensure sufficient flame retardant characteristics. However, when using an excessive amount of solid flame retardants, there is a risk of deterioration of optical properties, and when using liquid flame retardants, the adhesion and durability are weak due to fluidity, so there is a problem that they are not suitable as protective materials.

[0004] Therefore, the inventors continued their research on developing a protective material that could solve the above problems. As a result, they confirmed that when a solid-phase flame retardant having an appropriate D90 particle size and an appropriate phosphorus content is used, it not only exhibits excellent flame retardancy but also excellent optical properties and durability, making it suitable for application to LED displays and the like, thus completing the present invention. [Disclosure of the Invention] [Problems that the invention aims to solve]

[0005] The present invention aims to provide a UV-curable protective material composition with excellent flame retardancy and an LED display using the same.

[0006] The technical problems of the present invention are not limited to those described above, and other technical problems not mentioned can be clearly understood by those skilled in the art from the following description. [Means for solving the problem]

[0007] According to one embodiment of the present invention, an ultraviolet-curable protective material composition is provided, comprising an oligomer having at least one skeleton selected from polyisobutylene and hydrogenated polybutadiene and having a bifunctional acrylic group; an acrylic monomer; a photoinitiator; and a solid-phase flame retardant containing phosphorus, wherein the solid-phase flame retardant has a D90 particle size of 2 to 20 μm, and the phosphorus is present in an amount of 10% by weight or more based on the total weight of the solid-phase flame retardant.

[0008] Furthermore, the UV-curable protective material composition may have a viscosity of 10 to 3000 cps before UV curing.

[0009] Furthermore, the UV-curable protective material composition may have a light transmittance of 75% or more at a thickness of 50 μm after UV curing.

[0010] Furthermore, the UV-curable protective material composition can have a tack force of 20 gf or less after UV curing.

[0011] Furthermore, the solid-phase flame retardant may be a non-halogen solid-phase flame retardant.

[0012] Furthermore, the solid-phase flame retardant may include organic flame retardants and inorganic flame retardants.

[0013] Furthermore, the UV-curable protective material composition may have a Young's modulus of 100 to 7000 MPa at 25°C.

[0014] Furthermore, the UV-curable protective material composition may further contain at least one of the following: pigments, dyes, antioxidants, heat stabilizers, UV stabilizers, UV absorbers, and antistatic agents.

[0015] According to another embodiment of the present invention, a circuit board or display panel comprising the ultraviolet-curable protective material composition is provided. [Effects of the Invention]

[0016] The ultraviolet-curable protective material composition of the present invention has excellent flame retardancy and optical properties and is suitable for protecting printed circuit boards (PCBs), LEDs, and LED displays.

[0017] Specifically, the UV-curable protective material composition has excellent flame retardancy despite not containing halogen-based flame retardants, and excellent light transmittance despite containing solid-phase flame retardants, making it suitable for application to LED displays.

[0018] Furthermore, the UV-curable protective material composition has an optimal Young's modulus and tack force for use as a flame-retardant protective material, exhibits excellent resistance to physical damage, and may have superior appearance and adhesion to the substrate.

[0019] Therefore, a printed circuit board or an LED display to which the ultraviolet curable protective material composition of the present invention is applied is excellent in resistance to physical impact and flame retardancy, and can also have excellent quality as a display.

Brief Description of Drawings

[0020] In order to more fully understand the drawings cited in the detailed description of the present invention, a brief description of each drawing is provided. [Figure 1] It shows a cross-sectional view of an LED display panel according to an embodiment of the present invention. [Figure 2] It shows a cross-sectional view of an LED display panel according to another embodiment of the present invention. (Detailed Description of the Invention)

Mode for Carrying Out the Invention

[0021] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. Generally, the nomenclature used in this specification is well known and commonly used in the technical field.

[0022] Also, in describing the embodiments of the present invention, if a specific description of a related known configuration or function is determined to impede the understanding of the embodiments of the present invention, the detailed description thereof will be omitted.

[0023] Also, the embodiments of the present invention will be described below, but the technical idea of the present invention is not limited or restricted thereto, and can be variously implemented by being modified by those skilled in the art.

[0024] In this specification, when a part is said to be "connected", "attached", "adhered" or "bonded" to another part, this includes not only the case where it is "directly connected", but also the case where it is "electrically connected" through another element in between.

[0025] In this specification, when we say that one member is located "above," "above," "below," or "below" another member, this includes not only cases where one member is in contact with another member, but also cases where another member exists between the two members.

[0026] In this specification, when we say that a member is located "directly on top of," "directly above," "directly at the top end," "directly below," "directly below," or "directly at the bottom end" of another member, it means that it is in contact with the other member and there is no other member between the two members.

[0027] In this specification, spatially relative terms such as "below," "beneath," "lower," "above," and "upper" may be used to easily describe the correlation with components as shown in the drawings.

[0028] In this specification, when a part is said to contain a component, this means that, unless otherwise stated, it may contain other components rather than excluding them.

[0029] In this specification, the terms and / or include a combination of multiple related items or any one of multiple related items.

[0030] According to one embodiment of the present invention, an ultraviolet-curable protective material composition is provided, comprising an oligomer having at least one skeleton selected from polyisobutylene and hydrogenated polybutadiene and having a bifunctional acrylic group; an acrylic monomer; a photoinitiator; and a solid-phase flame retardant containing phosphorus, wherein the solid-phase flame retardant has a D90 particle size of 2 to 20 μm, and the phosphorus is present in an amount of 10% by weight or more based on the total weight of the solid-phase flame retardant.

[0031] In the present invention, when phosphorus is thermally decomposed by heat, it produces phosphoric acid and / or metaphosphoric acid, which then undergo esterification and / or dehydrogenation reactions to form a protective layer containing carbon (charcoal), thereby blocking oxygen and exhibiting flame retardant properties. Therefore, the inventors have ensured that the ultraviolet-curable protective material composition contains a sufficient amount of phosphorus to impart flame retardancy and exhibit excellent flame retardant properties. Specifically, in the present invention, phosphorus is contained in an amount of 10% by weight or more based on the total weight of the solid-phase flame retardant, and if the phosphorus content is less than 10% by weight based on the total weight of the solid-phase flame retardant, the flame retardant properties may decrease.

[0032] In this specification, "phosphorus content" refers to the total content, including not only the amount of pure phosphorus contained in the solid-phase flame retardant, but also the amount of phosphorus contained within the phosphorus-containing compounds in the solid-phase flame retardant.

[0033] Furthermore, the inventors confirmed that when the D90 particle size of the solid-phase flame retardant is 2 to 20 μm, it simultaneously satisfies excellent flame retardancy and optical properties. Specifically, the flame retardant generates phosphoric acid and / or metaphosphoric acid by thermal decomposition to form a protective layer, blocking oxygen and preventing combustion. When the D90 particle size is less than 2 μm, it is difficult to form a protective layer of easily combustible organic matrix, and the flame retardant role is insufficient. When the D90 particle size of the solid-phase flame retardant exceeds 20 μm, the gaps between the flame retardant particles become wider, reducing its ability to delay the ignition of the organic matrix, and the flame retardant properties become weaker. In addition, when the D90 particle size exceeds 20 μm, it reduces the optical performance when used as a material to protect the top of an LED.

[0034] In this specification, "D90 particle size" refers to the particle size that corresponds to 90% of the cumulative percentage of particles when particles with different size intervals are accumulated from smallest to largest in the total amount of powder. For example, if the D90 particle size is 25 μm, it means that the number of particles with a particle size of 25 μm or less corresponds to 90% of the total number of particles, and the number of particles with a particle size greater than 25 μm corresponds to 10% of the total number of particles. D50 (average particle size), which represents a general particle size, refers to the particle size that corresponds to the cumulative percentage distribution and differs from the D90 particle size. The D90 particle size cannot be estimated through D50, and even if the D50 sizes are similar, the D90 sizes may differ due to the particle size distribution.

[0035] In this specification, "oligomer" may mean a polymer obtained by polymerizing monomers to a degree of polymerization of 5 to 10,000. Therefore, "oligomer having two functional acrylic groups" in this specification may mean a polymer having two functional acrylic groups obtained by polymerizing monomers to a degree of polymerization of 5 to 10,000.

[0036] The UV-curable protective material composition of the present invention, by including an oligomer having a backbone selected from polyisobutylene and hydrogenated polybutadiene and having a bifunctional acrylic group, can significantly reduce moisture and gas permeability and provide a protective layer with outstanding protective performance and excellent durability for LEDs mounted on at least one of the printed circuit boards or displays. If the oligomer has one acrylic functional group, the UV curing speed may be significantly reduced, or the durability reliability may decrease due to uncured material. If there are three or more acrylic functional groups, the crosslinking density increases, causing cracks to occur in the cured protective material composition, leading to separation between the LED and solder resist layer in contact with the protective layer, and significantly reducing durability reliability.

[0037] In one embodiment, the solid-phase flame retardant of the present invention may be a non-halogen solid-phase flame retardant. By including the non-halogen solid-phase flame retardant, the harmful effects of the protective material composition of the present invention on the environment or human health can be significantly reduced.

[0038] In one embodiment, the solid-phase flame retardant of the present invention may include an organic flame retardant and an inorganic flame retardant. By including both the organic and inorganic flame retardants, the UV-curable protective material composition can be provided with superior flame retardant properties. For example, the solid-phase flame retardant of the present invention may include a non-halogen organic flame retardant and a non-halogen inorganic flame retardant. The UV-curable protective material composition of the present invention can exhibit superior flame retardant properties even when it includes the non-halogen organic flame retardant and the non-halogen inorganic flame retardant.

[0039] In this specification, "organic flame retardant" means a flame retardant containing the element carbon (C), and "inorganic flame retardant" means a flame retardant that does not contain the element carbon (C).

[0040] In one embodiment, the solid-phase flame retardant of the present invention may include, but is not limited to, aromatic phosphate esters, monosubstituted phosphonic acid diesters, disubstituted phosphinic acid esters, metal salts of disubstituted phosphinic acids, nitrogen-containing phosphorus compounds, cyclic phosphorus compounds, alkyl phosphinate salts, aluminum phosphites, and phosphine oxides.

[0041] Examples of the aromatic phosphate esters include at least one selected from 1,3-phenylenebis(di-2,6-xylenyl phosphate), bisphenol α-bis(diphenyl phosphate), and 1,3-phenylenebis(diphenyl phosphate).

[0042] Examples of the monosubstituted phosphonic acid diester include at least one selected from divinyl phenylphosphonate, diallyl phenylphosphonate, and bis(1-butenyl) phenylphosphonate.

[0043] Examples of the aforementioned disubstituted phosphinate esters include at least one selected from phenyl diphenylphosphinate and methyl diphenylphosphinate.

[0044] Examples of the nitrogen-containing phosphorus compounds include phosphazene compounds such as hexaphenoxycyclotriphosphazene, bis(2-allylphenoxy)phosphazene, and dicresylphosphazene; melamine compounds such as melamine phosphate, melamine pyrophosphate, melamine polyphosphate, and melamine polyphosphate; and at least one of the following: ammonium polyphosphate, ammonium phosphate, monoammonium phosphate, disammonium phosphate, tertammonium phosphate, and polyammonium phosphate.

[0045] Examples of the cyclic phosphorus compound include at least one selected from 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 10-(2,5-dihydroxyphenyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

[0046] Examples of the alkyl phosphinate salt include at least one of the following: aluminum diethyl phosphinate, aluminum methyl ethyl phosphinate, titanyl bis-diethyl phosphinate, titanium tetrakiss-diethyl phosphinate, titanyl bis-methyl ethyl phosphinate, titanium tetrakiss-methyl ethyl phosphinate, zinc bis-diethyl phosphinate, and zinc bis-methyl ethyl phosphinate.

[0047] In one embodiment, the oligomer having at least one skeleton selected from polyisobutylene and hydrogenated polybutadiene has a weight-average molecular weight (Mw) of 3,000 to 100,000, specifically 5,000 to 95,000. In this case, if the weight-average molecular weight is 3,000 or less, the durability reliability after UV curing may be poor due to high crosslinking density and brittleness, and if it is 100,000 or more, UV curing may not proceed smoothly, and problems may arise in which durability reliability is poor due to unreacted substances.

[0048] In one embodiment, the content of the oligomer having at least one skeleton selected from polyisobutylene and hydrogenated polybutadiene can be 10 to 50 parts by weight. If the oligomer content is less than 10 parts by weight, problems such as damage to the LED and corrosion of the circuit surface exposed on the printed circuit board may occur due to a decrease in external moisture barrier properties. If it exceeds 50 parts by weight, problems such as easy generation of bubbles during application due to high viscosity and difficulty in removal arise.

[0049] In one embodiment, the acrylic monomer may contain functional groups that can chemically bond with solder resist formed on the uppermost part of the printed circuit board.

[0050] In one embodiment, the acrylic monomer is methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, sec-butyl (meth)acrylate, pentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-hexyl acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, isononyl At least one of the following can be used: acrylic (meth)acrylate, isobornyl (meth)acrylate, glycidyl (meth)acrylate, hydroxyethyl (meth)acrylate, lauryl (meth)acrylate, and tetradecyl (meth)acrylate, benzyl (meth)acrylate, cyclohexyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, or morpholinyl (meth)acrylate, (meth)acrylate having an alkoxy group, or acrylic acid. Specifically, the acrylic monomer may contain one or more of the following: epoxy, isocyanate, hydroxy, silane, amide, or amine.

[0051] In one embodiment, the acrylic monomer may be epoxy (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 3-(meth)acryloyloxypropyltriethoxysilane, 3-(meth)acryloyloxypropyltrimethoxysilane, N,N-dimethylacrylamide, N,N-diethylacrylamide, or (meth)acryloyloxyethyl isocyanate, and specifically epoxy (meth)acrylate may be used. In this case, the adhesion between the cured protective material composition of the present invention and the solder resist on the surface of the printed circuit board is improved, durability and reliability are enhanced, and the occurrence of bubbles and peeling is prevented.

[0052] In one embodiment, the acrylic monomer content may be 50 to 90 parts by weight. If the acrylic monomer content is less than 50 parts by weight, the high viscosity causes bubbles to form when the UV-curable protective material composition is applied, and these bubbles are difficult to remove. If the content exceeds 90 parts by weight, the toughness of the cured protective material composition is weak, and cracks easily form due to physical impact.

[0053] The photoinitiator can be one that becomes active upon exposure to ultraviolet light, and when the photoinitiator is irradiated with ultraviolet light (UV light), it generates radicals that initiate polymerization. In the present invention, the photoinitiator can be any common photoinitiator component that can be used in the industry without limitation, and a variety of photoinitiators such as benzophenone and acetophenone ketones, peroxide or phosphine oxide systems, benzoin, benzoin ether, benzyl, and benzyl ketal can be selected and used as the photoinitiator component. Specific examples include 1-Hydroxycyclohexyl phenyl ketone, 1-Hydroxy-2-methyl-1-phenylpropane-1-ketone, 2-Chlorothioxantone, 2-Isopropylthioxantone, 2,2-Dimethoxy-2-phenylacetophenone, and 2,4,6-Trimethylbenzoyl-diphenylphosphine oxide. At least one of the following can be used: oxide, ethyl(2,4,6-trimethylbenzoyl)-phenylphosphinate, bis(2,4,6-trimethylbenzoyl)-phenylphosphineoxide, and benzophenone.

[0054] In one embodiment, the photoinitiator may be present in an amount of 0.05 to 5 parts by weight. If the photoinitiator content is less than 0.05 parts by weight, UV curing is unlikely to proceed sufficiently, and if it exceeds 5 parts by weight, unreacted photoinitiator may remain in the cured protective material composition, which may cause yellowing.

[0055] In one embodiment, the solid-phase flame retardant may be included in an amount of 20 to 100 parts by weight per 100 parts by weight of an oligomer having at least one skeleton selected from polyisobutylene and hydrogenated polybutadiene and having a bifunctional acrylic group, and an acrylic monomer.

[0056] In one embodiment, the UV-curable protective material composition of the present invention may further contain one or more of the following: pigments, dyes, antioxidants, heat stabilizers, UV stabilizers, UV absorbers, flame retardants, and antistatic agents. The aforementioned components can be any known substances without limitation. The amounts of the aforementioned components are not particularly limited and can be easily selected by those skilled in the art within a range that does not impair the purpose and effects of the present invention.

[0057] In one embodiment, the UV-curable protective material composition of the present invention can have a viscosity of 10 to 3,000 cps before UV curing, specifically in the range of 100 to 2,500 cps. Having a viscosity in this range eliminates the possibility of bubble generation around the LEDs when applying the protective material composition, thereby preventing a decrease in the image quality and performance of the display. On the other hand, if the viscosity of the UV-curable protective material composition exceeds 3,000 cps, bubbles are likely to occur around the LEDs when applying the UV-curable protective material composition to the printed circuit board, and it may be difficult to remove the generated bubbles. Consequently, this can lead to a decrease in the optical characteristics of the display device and cause durability, reliability, and / or appearance defects.

[0058] In one embodiment, the UV-curable protective material composition of the present invention may have a Young's modulus of 100 to 7,000 MPa at 25°C, specifically, 120 MPa to 6,500 MPa. When the above numerical range is met, the UV-curable protective material composition may have the ability to adequately protect printed circuit boards and components laminated on the printed circuit board, including LEDs, from physical impact. On the other hand, if the Young's modulus is less than 100 MPa, the protective material composition has weak resistance to physical damage, and if it exceeds 7,000 MPa, cracks may occur in the protective material composition when a physical impact is applied, limiting its ability to adequately protect LEDs under durable reliability conditions.

[0059] In one embodiment, the UV-curable protective material composition of the present invention may have a tack force of 20 gf or less after UV curing. In a specific embodiment, the UV-curable protective material composition may be applied to one surface of a printed circuit board and UV-cured to form a protective layer constituting the outermost surface of an LED display. In this case, since the tack force after UV curing is less than 20 gf and the protective layer has a tackiness of less than or equal to a predetermined value, the surface of the protective layer exposed to the outside may not be contaminated, and there is no concern about damage to the image quality of the LED display.

[0060] In one embodiment, the UV-curable protective material composition of the present invention may have a light transmittance of 75% or more at a thickness of 50 μm after UV curing. Having this light transmittance, the UV-curable protective material composition of the present invention possesses both excellent flame retardancy and optical properties, making it suitable as a composition for protecting printed circuit boards and / or LED displays.

[0061] According to another embodiment of the present invention, a printed circuit board or display panel comprising the ultraviolet-curable protective material composition of the present invention is provided.

[0062] A printed circuit board (PCB) means a substrate on which electronic elements can be mounted, which can mount various types of electronic elements, and which can be connected together. Examples of such elements may include, but are not limited to, passive elements such as resistors, capacitors, inductors, transformers, and diodes; active elements such as transistors and integrated circuits; power elements such as voltage regulators and relays; signal elements such as oscillators and sensors; optoelectronic elements such as LEDs, OLEDs, photodiodes, and LCDs; and memory elements such as flash memory and DRAM.

[0063] The printed circuit board can be protected by forming a protective layer containing the ultraviolet-curable protective material composition of the present invention, thereby protecting various electronic elements mounted on the board.

[0064] A display panel refers to a component that generates the image on a display. The display panel may include the ultraviolet-curable protective material composition of the present invention and at least one display device selected from LEDs, OLEDs, and LCDs, and the excellent optical properties of the protective material composition enable the realization of a display with excellent image quality.

[0065] Figure 1 shows an example of an LED display panel to which the UV-curable protective material composition of the present invention is applied, and shows a cross-sectional view of the LED display panel including a protective layer formed with the UV-curable protective material composition of the present invention.

[0066] One embodiment of the present invention provides an LED display (100) comprising: a printed circuit board (PCB) (140); an electrode layer (110) located on at least a portion of the uppermost front surface of the printed circuit board (140); solder (120) formed on at least a portion of the electrode layer (110); an LED (130) located on the solder (120) and connected to the electrode layer (110); and a solder resist (150) located on the uppermost front surface of the printed circuit board (140), excluding the area of ​​the electrode layer (110); and a protective layer (160) applied to the front surface of the printed circuit board (140) in which the area of ​​the electrode layer (110) and the solder resist (150) are laminated.

[0067] In one embodiment of the present invention, the thickness of the protective layer (160) layer, measured from the top layer of the printed circuit board (140), may be equal to or greater than the sum of the solder thickness and the LED thickness.

[0068] One or more other layers may be laminated on the protective layer (160), or the protective layer (160) may constitute the outermost surface of the LED display.

[0069] The protective layer (160) is formed by UV curing of the UV-curable protective material composition of the present invention, and has excellent adhesion to the surface of the printed circuit board (140), strong resistance to external impacts and scratches, and can perform the physical protection function of the LED (130). In addition, the protective layer (160) optimizes the optical properties to prevent a decrease in the light emission characteristics of the LED (130). Through such a design, high image quality and durability can be maintained simultaneously in the LED display device. Furthermore, the protective layer (160) protects the LED by having low transmittance to moisture, excellent weather resistance and durability, while being designed to minimize damage to the image quality of the LED display caused by the protective layer (160).

[0070] In another embodiment of the present invention, the LED display embodying the present invention may include a light-modulating film on top of the protective layer. The light-modulating film can be any film having the function of diffusing, refraction, reflecting, dispersing, or absorbing light, and may be used selectively for the purpose of improving the visibility and color viewing angle of the LED display.

[0071] Figure 2 shows a cross-sectional view of an LED display panel including the protective layer, as another embodiment of the present invention.

[0072] As shown in Figure 2, the protective layer (160) has a structure that extends to the side surface of the printed circuit board (140), thereby protecting the LED (130) from external impacts and protecting the LED (130) and the circuit surface from external heat and humidity.

[0073] The following examples and experimental illustrations illustrate the present invention in more detail, but the present invention is not limited thereto.

[0074] [Manufacturing example] <Manufacturing of Example 1> A bifunctional acrylate oligomer having a polyisobutylene structure and a weight-average molecular weight of 27,000 was uniformly blended with 35 parts by weight of isobornyl acrylate, 12 parts by weight of isooctyl acrylate, and 8 parts by weight of glycidyl methacrylate. To 100 parts by weight of the above mixture, 68 parts by weight of aluminum diethyl phosphinate (a non-halogen solid-phase organic flame retardant) with a phosphorus content of 24% by weight and a D90 particle size of 10 μm, based on the total weight of the solid-phase organic flame retardant, was added. Further, 1.0 part by weight of 2,2-dimethoxy-2-phenylacetophenone (Irgacure 651, manufactured by Ciba Specialty Chemicals), a photoinitiator, was added, mixed, and degassed to produce an ultraviolet-curable protective material composition.

[0075] <Manufacturing of Example 2> The compound consists of 16 parts by weight of a bifunctional acrylate oligomer containing a hydrogenated polybutadiene structure with a weight-average molecular weight of 45,000, uniformly blended with 39 parts by weight of isobornyl acrylate, 25 parts by weight of lauryl methacrylate, 5 parts by weight of hydroxybutyl acrylate, and 15 parts by weight of glycidyl methacrylate. To 100 parts by weight of the above compounding solution, 20 parts by weight of hexaphenoxycyclotriphosphazene (a non-halogen solid-phase organic flame retardant) having a phosphorus content of 13% by weight and a D90 particle size of 5 μm based on the total weight of the solid-phase organic flame retardant, and 10 parts by weight of ammonium polyphosphate (a non-halogen solid-phase inorganic flame retardant) having a phosphorus content of 30% by weight and a D90 particle size of 18 μm based on the total weight of the solid-phase inorganic flame retardant were added. Further, 1.0 part by weight of 2,2-dimethoxy-2-phenylacetophenone (Irgacure 651, manufactured by Ciba Specialty Chemicals), a photoinitiator, was added, mixed, and degassed to produce an ultraviolet-curable protective material composition.

[0076] <Manufacturing of Comparative Example 1> A bifunctional acrylate oligomer having a polyisobutylene structure and a weight-average molecular weight of 27,000 was uniformly blended with 35 parts by weight of isobornyl acrylate, 12 parts by weight of isooctyl acrylate, and 8 parts by weight of glycidyl methacrylate. To 100 parts by weight of the above mixture, 54 parts by weight of triphenyl phosphate (a non-halogen solid-phase organic flame retardant) with a phosphorus content of 9% by weight and a D90 particle size of 3 μm, based on the total weight of the solid-phase organic flame retardant, was added. Further, 1.0 part by weight of 2,2-dimethoxy-2-phenylacetophenone (Irgacure 651, manufactured by Ciba Specialty Chemicals), a photoinitiator, was added, mixed, and degassed to produce an ultraviolet-curable protective material composition.

[0077] <Manufacturing of Comparative Example 2> A bifunctional acrylate oligomer having a polyisobutylene structure and a weight-average molecular weight of 27,000 was uniformly blended with 35 parts by weight of isobornyl acrylate, 12 parts by weight of isooctyl acrylate, and 8 parts by weight of glycidyl methacrylate. To 100 parts by weight of the above mixture, 68 parts by weight of aluminum diethyl phosphinate (a non-halogen solid-phase organic flame retardant) with a phosphorus content of 24% by weight and a D90 particle size of 31 μm, based on the total weight of the solid-phase organic flame retardant, was added. Further, 1.0 part by weight of 2,2-dimethoxy-2-phenylacetophenone (Irgacure 651, manufactured by Ciba Specialty Chemicals), a photoinitiator, was added, mixed, and degassed to produce an ultraviolet-curable protective material composition.

[0078] <Manufacturing of Comparative Example 3> A bifunctional acrylate oligomer having a polyisobutylene structure and a weight-average molecular weight of 27,000 was uniformly blended with 35 parts by weight of isobornyl acrylate, 12 parts by weight of isooctyl acrylate, and 8 parts by weight of glycidyl methacrylate. To 100 parts by weight of the above mixture, 55 parts by weight of a cyclic phosphate ester (non-halogenated liquid organic flame retardant) with a phosphorus content of 20% by weight based on the total weight of the liquid organic flame retardant was added, and 1.0 part by weight of 2,2-dimethoxy-2-phenylacetophenone (Irgacure 651, manufactured by Ciba Specialty Chemicals), a photoinitiator, was further added, mixed, and degassed to produce an ultraviolet-curable protective material composition.

[0079] <Manufacturing of Comparative Example 4> A tetrafunctional acrylate oligomer containing a hydrogenated polybutadiene structure and having a weight-average molecular weight of 19,000 was uniformly blended with 24 parts by weight of lauryl methacrylate, 35 parts by weight of isobornyl acrylate, and 6 parts by weight of glycidyl methacrylate. To 100 parts by weight of the above mixture, 45 parts by weight of aluminum diethyl phosphinate (a non-halogen solid-phase organic flame retardant) with a phosphorus content of 24% by weight and a D90 particle size of 10 μm, based on the total weight of the solid-phase organic flame retardant, was added. Further, 1.0 part by weight of 2,2-dimethoxy-2-phenylacetophenone (Irgacure 651, manufactured by Ciba Specialty Chemicals), a photoinitiator, was added, mixed, and degassed to produce an ultraviolet-curable protective material composition.

[0080] [Example of experiment] (1) Flame retardancy evaluation A PCB panel on which LEDs with a height of 250 μm were mounted was coated with the compositions prepared in the above examples and comparative examples to a total height of 500 μm. A polyester release film was then laminated onto the protective layer applied to prevent contact with oxygen. Subsequently, a 365 nm LED ultraviolet lamp was used to apply a light intensity of 3000 mJ / cm². 2 The polyester release film surface was cured by irradiating it with ultraviolet light, and then the polyester release film was removed to complete the LED panel.

[0081] The panels manufactured as described above were cut to a width of 13 mm and a length of 125 mm to prepare five or more samples, and their flame retardancy was evaluated using the UL94V test method as described below.

[0082] 1) After applying a 20 mm long flame to the test specimen for 10 seconds, measure the burning time t1 of the test specimen and record the combustion pattern.

[0083] 2) After the initial flame application and once combustion has finished, the specimen is flamed again for 10 seconds, and the burning time t2 and afterglow time t3 of the test specimen are measured to record the combustion pattern.

[0084] 3) Determine the burning time and characteristics of t1, t2, and t3 (whether or not the absorbent cotton ignites due to dripping material, whether or not it burns up to the clamp, etc.), and calculate the grade as shown in Table 1 below.

[0085] If a material does not fall into any of the following V-0, V-1, or V-2 grades (unclassified), it shall be deemed to lack flame retardancy.

[0086] [Table 1] (2) Light transmittance measurement The compositions prepared in the examples and comparative examples were applied to a polyester release film using a bar coater to a thickness of 50 μm to form a protective material layer. To prevent contact between the protective material layer and oxygen, an additional polyester release film was laminated on top of the formed protective layer. Subsequently, a 365 nm LED ultraviolet lamp was used to apply light at an intensity of 3000 mJ / cm². 2 To achieve this, the protective material layer was cured by irradiating it with ultraviolet light from one side, and then the release films on both sides were removed to produce a single sample of the UV-cured protective material layer.

[0087] After performing baseline calibration on the protective material manufactured as described above with no sample in the measurement area, the light transmittance was measured using an NDH-7000 (manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with the JIS K 7105 standard.

[0088] (3) Viscosity measurement The compositions prepared in the above examples and comparative examples were measured at room temperature using a Brookfield viscometer after adjusting the RPM to apply a torque of 20-40% with a No. 64 spindle.

[0089] (4) Measurement of Young's modulus The compositions prepared in the examples and comparative examples were applied to a polyester release film using a bar coater to form a protective material layer with a thickness of 500 μm. To prevent contact between the protective material layer and oxygen, an additional polyester release film was laminated on top of the formed protective layer. Subsequently, a 365 nm LED ultraviolet lamp was used to apply light at an intensity of 3000 mJ / cm². 2 To achieve this, the protective material layer was cured by irradiating it with ultraviolet light from one side, and then the release films on both sides were removed to produce a single sample of the UV-cured protective material layer.

[0090] The UV-cured protective material layer manufactured as described above was cut into strips 10 mm wide and 100 mm long to prepare test specimens. After maintaining the measurement environment at 25°C, the test specimens were fixed to jigs on both sides at 50 mm intervals using a UTM device, and then pulled at a speed of 100 mm / min until the sample fractured, obtaining a stress-strain curve. At this time, the slope in the section from a strain rate of 0.1% to a strain rate of 1% was calculated to obtain the value of Young's modulus.

[0091] (5) Measurement of tack strength A PCB panel on which LEDs with a height of 250 μm were mounted was coated with the compositions prepared in the above examples and comparative examples to a total height of 500 μm. A polyester release film was then laminated onto the protective layer applied to prevent contact with oxygen. Subsequently, a 365 nm LED ultraviolet lamp was used to apply a light intensity of 3000 mJ / cm². 2 The polyester release film surface was cured by irradiating it with ultraviolet light, and the polyester release film was removed to complete the LED panel. A texture analyzer was used to press a 1-inch SUS ball against the outermost protective layer surface at a speed of 0.1 mm / s to achieve a pressure of 800 gf. This pressure was held for 1 second, and the maximum force applied when the ball returned at a speed of 1 mm / s was recorded as the tack strength.

[0092] (6) Adhesion evaluation A PCB panel on which LEDs with a height of 250 μm were mounted was coated with the compositions prepared in the above examples and comparative examples to a total height of 500 μm. A polyester release film was then laminated onto the protective layer applied to prevent contact with oxygen. Subsequently, a 365 nm LED ultraviolet lamp was used to apply a light intensity of 3000 mJ / cm². 2 The polyester release film surface was cured by irradiating it with ultraviolet light, and the polyester release film was removed to complete the LED panel. The interface between the PCB and the protective material was separated from the side using a blade, and the adhesion was evaluated according to the following evaluation criteria.

[0093] O: No lifting or delamination of the PCB and protective material occurs. X: Lifting / delamination of the PCB and protective material occurs. (7) External observation A PCB panel on which LEDs with a height of 250 μm were mounted was coated with the compositions prepared in the above examples and comparative examples to a total height of 500 μm. A polyester release film was then laminated onto the protective layer applied to prevent contact with oxygen. Subsequently, a 365 nm LED ultraviolet lamp was used to apply a light intensity of 3000 mJ / cm². 2 The polyester release film surface was cured by irradiating it with ultraviolet light, and the polyester release film was removed to complete the LED panel. A microscope was used to observe for the presence or absence of air bubbles around the LEDs.

[0094] O: No bubbles are generated around the LED. X: Bubbles appear around the LED. (8) Durability and reliability A PCB panel on which LEDs with a height of 250 μm were mounted was coated with the compositions prepared in the above examples and comparative examples to a total height of 500 μm. A polyester release film was then laminated onto the protective layer applied to prevent contact with oxygen. Subsequently, a 365 nm LED ultraviolet lamp was used to apply a light intensity of 3000 mJ / cm². 2The polyester release film surface was cured by irradiating it with ultraviolet light, and the polyester release film was removed to complete the LED panel. The LED panel manufactured as described above was left for 300 hours under high temperature and high humidity conditions of 85°C and 85%RH, and then the appearance changes and the presence or absence of LED damage were observed.

[0095] O: No changes in appearance such as bubbles or lifting, and the entire unit lights up when operated without any LED damage. X: Appearance changes such as bubbles and lifting occur, and there are areas where the LED does not emit light when in operation due to LED damage. The experimental results obtained using the methods described in (1) to (8) above are shown in Table 2 below.

[0096] [Table 2] As shown in Table 2 above, both Examples 1 and 2 were confirmed to possess excellent flame retardancy of V-0 and have high light transmittance, resulting in superior optical properties. Furthermore, they were found to have an appropriate viscosity of 10 to 3000 cps before UV curing, making them suitable for application to printed circuit boards. When applied to LED displays, no bubbles were generated, and they were confirmed to have a Young's modulus of 100 to 7000 MPa, demonstrating excellent resistance to physical impact. Therefore, the UV-curable protective material composition of the present invention is confirmed to have excellent flame retardancy, optical properties, and resistance to physical impact, making it suitable for use as a composition for protecting printed circuit boards, LED displays, and the like.

[0097] On the other hand, in Comparative Example 1, which contained less phosphorus than the appropriate amount, and in Comparative Example 2, where the D90 particle size exceeded 20 μm, no flame retardancy grade was assigned, and it was confirmed that the flame retardancy properties were poor. In Comparative Example 3, which used a liquid flame retardant, both the flame retardancy properties and light transmittance were poor compared to the examples, and it was confirmed that the tack strength was very high and it was vulnerable to contamination, and that it had a remarkably low Young's modulus, resulting in extremely poor resistance to physical impact. In the case of Comparative Example 4, which contained a tetrafunctional acrylate oligomer containing four functional groups, it was confirmed that the durability reliability under high temperature and high humidity conditions was poor and it was not suitable for protective material compositions such as LEDs.

[0098] Therefore, it was confirmed that using a solid-phase flame retardant containing an appropriate amount of phosphorus and satisfying the D90 particle size is an important configuration for realizing the present invention.

[0099] Although specific aspects of the present invention have been described in detail above, it will be obvious to those with ordinary skill in the art that such specific descriptions are merely preferred embodiments and do not limit the scope of the invention. Therefore, the substantial scope of the invention should be defined by the appended claims and their equivalents. [Explanation of Symbols]

[0100] 100: LED display 110: Electrode layer 120: Solder 130: LED 140: Printed circuit board (PCB) 150: Solder Resist 160:Protective layer

Claims

1. UV-curable protective material composition, An oligomer having at least one skeleton selected from polyisobutylene and hydrogenated polybutadiene, and having a bifunctional acrylic group, Acrylic monomers and, A photoinitiator and a solid-phase flame retardant containing phosphorus are included, The solid-phase flame retardant has a D90 particle size of 2 to 20 μm. The ultraviolet-curable protective material composition is characterized in that the phosphorus is present in an amount of 10% by weight or more based on the total weight of the solid-phase flame retardant.

2. In the ultraviolet-curable protective material composition according to claim 1, The UV-curable protective material composition is characterized by having a viscosity of 10 to 3000 cps before UV curing.

3. In the ultraviolet-curable protective material composition according to claim 1, The UV-curable protective material composition is characterized in that, after UV curing, it has a light transmittance of 75% or more at a thickness of 50 μm.

4. In the ultraviolet-curable protective material composition according to claim 1, The UV-curable protective material composition is characterized by having a tack strength of 20 gf or less after UV curing.

5. In the ultraviolet-curable protective material composition according to claim 1, The aforementioned solid-phase flame retardant is a non-halogen solid-phase flame retardant, characterized by being an ultraviolet-curable protective material composition.

6. In the ultraviolet-curable protective material composition according to claim 1, The solid-phase flame retardant is characterized by comprising an organic flame retardant and an inorganic flame retardant, and is an ultraviolet-curable protective material composition.

7. In the ultraviolet-curable protective material composition according to claim 1, The UV-curable protective material composition is characterized by having a Young's modulus of 100 to 7000 MPa at 25°C.

8. In the ultraviolet-curable protective material composition according to claim 1, The UV-curable protective material composition is characterized by further comprising at least one of the following: a pigment, a dye, an antioxidant, a heat stabilizer, a UV stabilizer, a UV absorber, and an antistatic agent.

9. A circuit board or display panel characterized by comprising the ultraviolet-curable protective material composition described in any one of claims 1 to 8.

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