Light-curable resin composition for electrode protection and preparation method thereof

Abstract

The present invention relates to a photocurable resin composition for electrode protection and a method for preparing the same, and more specifically, to a photocurable resin composition for protecting an electrode portion where an ITO / Ag electrode is connected to a flexible printed circuit board such as a display panel from external factors, and a method for preparing the same.

Description

Technical Field

[0001] The present invention relates to a photocurable resin composition for electrode protection and a method for preparing the same, and more specifically, to a photocurable resin composition for protecting an electrode portion where an ITO / Ag electrode is connected to a flexible circuit board of a display panel or the like from external factors and a method for preparing the same. Background Art

[0002] With the weight reduction and multifunctionalization of electrical devices in recent years, components and electrodes in products are further densely integrated, and printed circuit boards mounted on various electrical devices to control the electrical devices are very sensitive to even slight changes in the external environment, causing problems in the electrical devices. Therefore, it has become necessary to insulate the printed circuit boards to protect them from the external environment (e.g., dust, moisture, vibration, gas, etc.).

[0003] In the insulation method, protective coatings with coatings are widely used, such as acrylic resins, urethane resins, silicone moisture-curing resins, epoxy-based thermosetting resins, etc. In general, acrylic resins and urethane resins are applied in a state dissolved in an organic solvent, and then dried to form a coating for the final purpose. However, this type of moisture-proof insulating coating agent allows the organic solvent to be discharged into the atmosphere during the coating, thereby causing air pollution and a serious environmental burden, and the risk of fire caused by the organic solvent is high. On the other hand, silicone moisture-curing resins and epoxy-based thermosetting resins require a long time of several minutes to several hours for curing and therefore have low productivity, the crosslinking density of silicone moisture-curing adhesives in the silicone structure is lower than that of light (ultraviolet) curing resins, and the disadvantage of epoxy-based thermosetting resins is insufficient moisture resistance because a large number of polar functional groups generated during curing lead to high moisture permeability.

[0004] As other methods, Japanese Unexamined Patent Publications No. 2006-342222 and No. 2004-107602 disclose a method for preparing an ultraviolet curing adhesive by connecting acrylic functional groups to both ends of an oligomer diol exhibiting extremely low polarity. However, although this method has good moisture resistance and productivity, it has a problem of poor adhesion to an electrode portion of an electronic component due to its low bonding strength.

[0005] As another method, Korean Early Publication No. 10-2005-000327 discloses a urethane (meth) acrylate ultraviolet (UV) curing adhesive. However, it has been found that although such an ultraviolet curing adhesive has good bonding strength to electrodes or glass, the ultraviolet curing adhesive forms a moisture belt between the adherend and the adhesive due to moisture penetration under high temperature / high humidity conditions, thereby causing a short circuit when used in integrated electronic products. Summary of the invention

[0006] Technical issues

[0007] Although urethane resins have the advantage of reducing processing time by allowing photocuring and having relatively good moisture resistance unlike silicone moisture-curing resins and epoxy-based thermosetting resins, urethane resins allow moisture penetration under high temperature / humidity conditions, resulting in a problem of deterioration in bonding strength.

[0008] Although various attempts have been made to improve the bonding strength, it is difficult to solve the problem of deterioration in processability, such as poor viscosity, stickiness of the resin surface after curing, etc., when improving the bonding strength. In addition, the stickiness of the resin surface means that the resin surface is contaminated by dust and other external environments during processing or use of electrical devices, thereby causing reliability problems not only for the moisture-proof insulator but also for various circuit boards and electrical devices using the moisture-proof insulator.

[0009] An object of the present invention is to provide a novel photocurable resin composition which allows rapid curing, has excellent moisture-proof insulation and bonding strength, does not form a tacky surface after curing, and ensures appropriate viscosity to provide good processability and workability.

[0010] Technical Solutions

[0011] According to one aspect of the present invention, there is provided a photocurable resin composition, the photocurable resin composition comprising: a urethane oligomer, a monomer having at least one unsaturated bond, and a photoinitiator,

[0012] The urethane oligomer is prepared by reacting a polyol with a polyisocyanate.

[0013] The polyol comprises at least two types of polyols,

[0014] The urethane oligomer includes a (meth)acrylate group at one or more terminals thereof, and at least one of the monomers includes a (meth)acrylate group.

[0015] Preferably, the photoinitiator comprises an aminoketone compound.

[0016] Preferably, the polyol includes at least one polyol having a weight average molecular weight of 1,000 g / mol or more and at least one polyol having a weight average molecular weight of less than 1,000 g / mol.

[0017] Preferably, the urethane oligomer is prepared by mixing at least two types of polyols with a polymerization inhibitor to prepare a mixture, and then adding the polyisocyanate to the mixture to react with the mixture.

[0018] Preferably, the urethane oligomer is prepared by reacting a polyol, a polyisocyanate and a capping monomer, and

[0019] The molar ratio of the polyol, the polyisocyanate and the end-capping monomer is in the range of N:N+1:2 or N+1:N:2, wherein N is a natural number of 1 to 10.

[0020] Preferably, the molar ratio of the polyol having a weight average molecular weight of 1,000 g / mol or more to the polyol having a weight average molecular weight of less than 1,000 g / mol is in the range of 3:1 to 1:3.

[0021] Preferably, the monomer has at least one functional group, and

[0022] The monomers include at least two types of monomers.

[0023] Preferably, the monomer comprises at least one (meth)acrylate group.

[0024] Preferably, the photoinitiator comprises an α-amino ketone compound.

[0025] Preferably, the photoinitiator includes at least one selected from the group consisting of 2-benzyl-2-(dimethylamino)-4′-morpholinobutyrophenone and 2-(4-methylbenzyl)-2-(dimethylamino)-1-(4-morpholinophenyl)butan-1-one.

[0026] Preferably, the photocurable resin composition further includes at least one selected from the group consisting of an adhesion enhancer, a surface tack enhancer, and a defoaming agent.

[0027] Preferably, the photocurable resin composition further comprises an adhesion enhancer,

[0028] The urethane oligomer is present in an amount of 40 to 60 parts by weight,

[0029] The monomer is present in an amount of 35 to 60 parts by weight,

[0030] The photoinitiator is present in an amount of 0.1 to 10 parts by weight, and

[0031] The adhesion enhancer is present in an amount of 1 to 3 parts by weight.

[0032] According to another aspect of the present invention, there is provided a method for preparing a photocurable resin composition, the method comprising: mixing a urethane oligomer, a monomer and a photoinitiator,

[0033] The urethane oligomer is prepared by mixing at least two types of polyols with a polymerization inhibitor to prepare a mixture, adding polyisocyanate to the mixture to react with the mixture, and adding a blocking monomer to the reaction mixture to react with the reaction mixture.

[0034] Preferably, a diluent is further added when the polyol is mixed with the polymerization inhibitor.

[0035] Preferably, the polyol comprises a mixture of a polyol having a weight average molecular weight of 1,000 g / mol or more and a polyol having a weight average molecular weight of less than 1,000 g / mol, and

[0036] The molar ratio of the polyol having a weight average molecular weight of 1,000 g / mol or more to the polyol having a weight average molecular weight of less than 1,000 g / mol is in the range of 3:1 to 1:3.

[0037] Beneficial Effects

[0038] The present invention provides a photocurable resin composition which allows rapid curing by photocuring to ensure good productivity and has good crosslinking density to ensure good moisture resistance and good insulation due to low moisture permeability and moisture absorption rate.

[0039] Furthermore, by adjusting the ratio of each component included in the photocurable resin composition according to the present invention, it is possible to ensure a viscosity suitable for the process while ensuring good bonding strength, and to improve processability and reliability by significantly reducing surface tack after curing. DETAILED DESCRIPTION

[0040] Unless otherwise defined herein, all terms (including technical or scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs. In addition, it should be understood that, unless otherwise defined, terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the specification and related technology, and should not be interpreted in an idealized or overly formal sense.

[0041] In addition, it should be further understood that when the terms "includes", "including", "comprises" and / or "comprising" are used in this specification, they specify the presence of stated features, integers, steps, operations, elements, components and / or groups, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0042] The photocurable resin composition according to one embodiment of the present invention is a urethane-based resin composition, and may include a urethane oligomer, one or more monomers, and a photoinitiator.

[0043] The urethane oligomer may include a reaction product prepared by reacting a polyol with a polyisocyanate. The polyol described herein refers to a compound including at least two hydroxyl groups, and the polyisocyanate refers to a compound including at least two isocyanate groups.

[0044] The polyol may include two hydroxyl groups per molecule, and is preferably a compound having hydroxyl groups at both ends thereof, respectively. More preferably, the polyol contains at least two types of polyols each having hydroxyl groups at both ends thereof, respectively.

[0045] When two or more types of polyols are used, the polyol may include at least one polyol having a weight average molecular weight of 1,000 g / mol or more and at least one polyol having a weight average molecular weight of less than 1,000 g / mol. Preferably, the molar ratio of the total moles of the polyols having a weight average molecular weight of 1,000 g / mol or more to the total moles of the polyols having a weight average molecular weight of less than 1,000 g / mol is in the range of 3:1 to 1:3, more preferably in the range of 1.5:1 to 1:1.5.

[0046] The polyol having a weight average molecular weight of 1,000 g / mol or more may have a weight average molecular weight of 1,000 g / mol to 3,000 g / mol, preferably 1,000 g / mol to 2,500 g / mol, more preferably 1,000 g / mol to 2,000 g / mol. For example, a double-terminal hydroxyl-terminated hydrogenated polybutadiene having a weight average molecular weight of 1,000 g / mol to 2,000 g / mol and having hydroxyl groups at both ends thereof may be used as the polyol having a weight average molecular weight of 1,000 g / mol or more.

[0047] The polyol having a weight average molecular weight of less than 1,000 g / mol may have an average molecular weight of 50 g / mol to 500 g / mol, preferably 80 g / mol to 300 g / mol, more preferably 100 g / mol to 200 g / mol. For example, ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, 2-butyl-2-ethyl-1,3-propanediol, etc. may be used as the polyol having a weight average molecular weight of less than 1,000 g / mol.

[0048] The polyisocyanate includes at least two isocyanate groups per molecule, and is preferably a compound in which the isocyanate groups are placed to have a chain structure by forming a urethane bond with a polyol having a hydroxyl group at both ends, respectively. The polyisocyanate may include at least two types of polyisocyanates as needed, as long as the characteristics of the present invention are not affected.

[0049] The polyisocyanate may be an aromatic polyisocyanate compound or an aliphatic polyisocyanate compound, preferably a diisocyanate.

[0050] The aromatic polyisocyanate compound may include, for example, toluene diisocyanate, methylene diphenyl diisocyanate, bis(isocyanatobutyl)benzene, bis(isocyanatomethyl)naphthalene, bis(isocyanatomethyl)diphenyl ether, phenylene diisocyanate, ethylphenylene diisocyanate, isopropyl phenylene diisocyanate, dimethyl phenylene diisocyanate, diethyl phenylene diisocyanate, diisopropyl phenylene diisocyanate, trimethylbenzene triisocyanate, benzene triisocyanate, biphenyl diisocyanate, toluidine diisocyanate, 4,4-diphenylmethane diisocyanate, 3,3-dimethyldiphenylmethane-4,4-diisocyanate, bibenzyl-4,4-diisocyanate, bis(isocyanatophenyl)ethylene, 3,3-dimethoxybiphenyl-4,4-diisocyanate, hexahydrophenyl diisocyanate, hexahydrodiphenylmethane-4,4-diisocyanate, preferably toluene diisocyanate or methylene diphenyl diisocyanate, but not limited thereto.

[0051] The aliphatic polyisocyanate compound may include, for example, isophorone diisocyanate (IPDI), 2,2-dimethylpentane diisocyanate, 2,2,4-trimethylhexane diisocyanate, butylene diisocyanate, 1,3-butadiene-1,4-diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, 1,6,11-undecane triisocyanate, 1,3,6-hexamethylene triisocyanate, 1,8-diisocyanate-4-isocyanatomethyl octane, octane), bis(isocyanatoethyl) carbonate, bis(isocyanatoethyl) ether, 1,2-bis(isocyanatomethyl) cyclohexane, 1,3-bis(isocyanatomethyl) cyclohexane, 1,4-bis(isocyanatomethyl) cyclohexane, cyclohexane diisocyanate, methylcyclohexane diisocyanate, dicyclohexyldimethylmethane isocyanate, 2,2-dimethyldicyclohexylmethane isocyanate, and the like, preferably isophorone diisocyanate, but is not limited thereto.

[0052] The carbamate oligomer can be end-capped with an end-capping monomer at both ends thereof. The end-capping monomer may include an alcohol or an isocyanate, preferably an alcohol. Preferably, the end-capping monomer includes a (meth) acrylate group at the end opposite to the end where the functional group including an alcohol group of the end-capping monomer is located. Specifically, the end-capping monomer may include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate and 2-hydroxy-3-phenoxypropyl (meth) acrylate, but is not limited thereto. When a monofunctional compound with a hydroxyl or isocyanate group is used as an end-capping monomer, curing is performed by the monofunctional group, thereby allowing rapid curing to reduce the surface viscosity of the resin composition after curing.

[0053] In the preparation of the urethane oligomer, a diluent may be further added. When two or more types of polyols are used, the diluent may contribute to the uniform dispersion of the polyols. Preferably, the diluent has a liquid phase and may include at least one selected from the group consisting of, for example, methyl (meth)acrylate, lauryl (meth)acrylate, isononyl acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, and combinations thereof, but is not limited thereto.

[0054] In addition, a polymerization inhibitor may be added. The polymerization inhibitor is used to prevent spontaneous polymerization during mixing and homogenization of at least two polyols (particularly polyols having a weight average molecular weight of 1,000 g / mol or more) with other polyols or components, and to adjust the rate of generation of urethane bonds, thereby enabling the preparation of urethane oligomers having a uniform molecular weight. For example, the polymerization inhibitor may include butylated hydroxytoluene, etc.

[0055] In the method for preparing carbamate oligomer according to one embodiment, at least two polyols can be mixed with a diluent and a polymerization inhibitor in a reactor and stirred together, and polyisocyanate and a reaction catalyst are sequentially added to the resulting mixture and stirred together with the resulting mixture, and then stirred to carry out a primary reaction while raising the temperature of the reactor. After that, the formation of carbamate bonds is checked by Fourier transform infrared spectroscopy (FT-IR) and the like, and the end-capping monomer can be added to the resulting mixture and stirred together with the resulting mixture to carry out a secondary reaction. When the inherent structure and carbamate bonds of the end-capping monomer in the final product are confirmed by FT-IR, the reaction is terminated. As a reaction catalyst, dibutyltin dilaurate and the like can be used.

[0056] In the preparation of the urethane oligomer, the reactor may have an initial temperature of about 30° C. to about 50° C., preferably about 35° C. to about 45° C. In addition, after increasing the temperature, the reactor may have a temperature of about 70° C. to about 100° C., preferably about 75° C. to 95° C., more preferably 80° C. to 90° C.

[0057] According to the molecular weight, properties, etc. of each component in the urethane oligomer, the molar ratio of the total mole number of polyols to the total mole number of end-capping monomers may be in the range of N:N+1:2 or N+1:N2, wherein N may be any natural number from 1 to 10, preferably from 1 to 5, and more preferably from 1 to 3. Specifically, for example, the molar ratio of polyol:polyisocyanate:end-capping monomer may be 2:3:2, wherein the urethane oligomer may have a structure of end-capping monomer-polyisocyanate-polyol-polyisocyanate-polyol-polyisocyanate-end-capping monomer.

[0058] In the urethane oligomer including polyol, polyisocyanate, blocking monomer and diluent, the diluent may be present in an amount of about 20 wt % to about 35 wt %, and the polyol, polyisocyanate and blocking monomer may be present in the above molar ratio.

[0059] According to the present invention, the monomer may have at least one functional group and may include at least two monomers. Preferably, the monomer has a (meth)acrylate group and is a mixture of at least two monomers having monofunctional to tetrafunctional groups.

[0060] The monofunctional (meth)acrylates may, for example, include: monofunctional (meth)acrylate compounds having a chain aliphatic group, such as isodecyl acrylate, isononyl acrylate, 2-ethylhexyl acrylate, isobutyl acrylate, tert-butyl acrylate, isooctyl acrylate, isoamyl acrylate, lauryl methacrylate, isononyl methacrylate, 2-ethylhexyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, isooctyl methacrylate, isoamyl methacrylate, etc.; monofunctional (meth)acrylate compounds having a cyclic aliphatic group, such as isobornyl (meth)acrylate, etc.; and monofunctional (meth)acrylate compounds having an aromatic group, such as benzyl acrylate, phenoxyethyl acrylate, benzyl methacrylate, phenoxyethyl methacrylate, 2-hydroxy-3-phenoxypropyl methacrylate, etc.

[0061] The multifunctional (meth)acrylate containing at least two (meth)acrylate groups may include at least one selected from the group consisting of, for example, 1,6-hexanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ethylene glycol di(meth)acrylate, tripropylene glycol diacrylate, trimethylolpropane trioxyethyl (meth)acrylate, tricyclodecane di(meth)ol diacrylate, tris(2-hydroxyethyl)isocyanurate di(meth)acrylate, tricyclodecane di(meth)ol di(meth)acrylate, propoxylated neopentyl glycol di(meth)acrylate, dicyclopentane diethyl di(meth)acrylate, bisphenol-A di(meth)acrylate, trimethylpropyl tri(meth)acrylate, and mixtures thereof.

[0062] Compared to multifunctional monomers, monofunctional chain (meth)acrylate monomers are used to reduce viscosity while increasing flexibility and allow rapid curing to improve processability, and compared to chain (meth)acrylate monomers, monofunctional cyclic (meth)acrylate monomers are used to reduce viscosity while improving bonding strength and post-curing strength. Multifunctional (meth)acrylate monomers are used to increase crosslinking density and post-curing strength.

[0063] Preferably, the monomer is a mixture of three or more types of monomers, more preferably a mixture of four or more types of monomers. In this case, when trifunctional or higher functional (meth)acrylate monomers are mixed, these monomers may be present in an amount of 5 wt % or less based on the total weight of the resin composition to prevent slow deep curing due to rapid surface curing, decreased productivity due to prolonged curing time, and increased likelihood of resin delamination from the substrate due to strength differences between the surface and deep sites, thereby reducing reliability.

[0064] The (meth)acrylate groups at the terminals of the monomers and urethane oligomers allow photocuring by ultraviolet light or the like, thereby enabling rapid curing while improving moisture insulation and adhesion by increasing crosslinking density.

[0065] According to the present invention, the photoinitiator may include an aminoketone compound, preferably an α-aminoketone compound. For example, the photoinitiator may include at least one selected from the group consisting of 2-benzyl-2-(dimethylamino)-4′-morpholinobutyrophenone and 2-(4-methylbenzyl)-2-(dimethylamino)-1-(4-morpholinophenyl)butan-1-one. These compounds exhibit good curability at a wavelength of 350 nm to 370 nm, preferably about 365 nm, corresponding to light emitted from a light emitting diode (LED) lamp. Among these compounds, 2-(4-methylbenzyl)-2-(dimethylamino)-1-(4-morpholinophenyl)butan-1-one is not registered as an environmentally restricted substance (EU Registration, Evaluation, Authorization and Restriction of Chemicals Regulation (EU reach)) and therefore does not require auxiliary procedures, such as compliance with requirements for processes and prerequisites involving the use of hazardous substances, and allows surface curing and deep curing to be performed at similar rates, thereby solving reliability problems such as swelling or delamination caused by the difference between the surface curing rate and the deep curing rate, while reducing surface tack.

[0066] The photocurable resin composition according to the present invention may further include at least one selected from the group consisting of an adhesion enhancer and a defoaming agent as an additive.

[0067] According to the present invention, the adhesion enhancer may include a mixture of one or more types of adhesion enhancers and is used to improve the bonding strength with substrate materials (e.g., glass and polyimide (PI) film). The adhesion enhancer may include epoxy compounds, oxetane compounds, morpholine compounds, various coupling agents, etc., preferably including curable morpholine compounds, silane coupling agents, etc.

[0068] According to the present invention, the morpholine compound preferably contains an acryloyl group, and may include, for example, 4-acryloylmorpholine.

[0069] According to the present invention, the silane coupling agent can be selected from any compound having at least one functional group reacting with an organic group and at least one hydrolyzable silicon group, but is not limited to a specific compound. The silane coupling agent improves the bonding strength, thereby improving the reliability of the final product. Preferably, the functional group reacting with the organic group includes at least one selected from epoxy, methacryloyl, acryloyl, isocyanate, isocyanurate, methacrylic, vinyl and carbamate. In terms of curability and adhesion, epoxy, methacryloyl and acryloyl are preferred. In terms of reactivity, preferably, the hydrolyzable silicon group includes alkoxysilyl, more preferably methoxysilyl and ethoxysilyl. Silane coupling agents include, for example, alkoxysilanes having epoxy functional groups, such as 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, etc.; alkoxysilanes having methacrylic or acrylic groups, such as 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-acryloxypropyltriethoxysilane, methacryloxymethyltrimethoxysilane, methacryloxymethyltriethoxysilane, acryloxymethyltrimethoxysilane, acryloxymethyltriethoxysilane, etc.; alkoxysilanes having methacryloyl or acryl groups, such as 3-(trimethoxysilyl)propyl(meth)acrylate, etc.

[0070] The adhesion enhancer is preferably a mixture of a morpholine compound and an alkoxysilane, more preferably a mixture of an acryl-containing morpholine compound and at least one of an acryl-containing alkoxysilane and an epoxy-containing alkoxysilane. However, when the morpholine compound is present in an amount greater than 2% by weight based on the total amount of the resin composition, the resin composition may suffer from reliability degradation due to increased surface strength compared to core strength, and when the morpholine compound is present in an amount greater than 1% by weight based on the total amount of the resin composition, the resin composition may suffer from storage stability and initial bonding strength degradation due to deterioration of compatibility between the compositions.

[0071] According to the present invention, the defoamer may be selected from any compound capable of removing air bubbles in the resin composition, but is not limited to a specific defoamer, and may include, for example, a silicone-based defoamer, a water-based silicone-free defoamer, etc. Preferably, a silicone-based defoamer having a formulation based on a degassing organic polymer and containing a trace amount of silicone is used.

[0072] In one embodiment, the photocurable resin composition may include: 40 to 60 parts by weight of urethane oligomer; 35 to 60 parts by weight of monomer; 0.1 to 10 parts by weight of photoinitiator; and 1 to 3 parts by weight of adhesion enhancer. Preferably, the photocurable resin composition may include: 45 to 55 parts by weight of urethane oligomer; 40 to 50 parts by weight of monomer; 0.1 to 5 parts by weight of photoinitiator; and 1 to 2.5 parts by weight of adhesion enhancer, more preferably: 50 to 55 parts by weight of urethane oligomer; 40 to 45 parts by weight of monomer; 0.1 to 3 parts by weight of photoinitiator; and 1.5 to 2.5 parts by weight of adhesion enhancer. Within these ranges, the photocurable resin composition has suitable viscosity, good bonding strength, and uniform surface curing and deep curing, thereby providing good moisture resistance and product reliability due to no expansion or delamination.

[0073] In one embodiment, the photocurable resin composition may be included in a carbamate oligomer having a (meth) acrylate group at one or more ends thereof, and at least one monomer having a (meth) acrylate group. Preferably, the photocurable resin composition includes a carbamate oligomer having a (meth) acrylate group at one or more ends thereof, at least two monomers each having a (meth) acrylate group, and at least one adhesion enhancer having a (meth) acrylate group. More preferably, the photocurable resin composition includes a carbamate oligomer having a (meth) acrylate group at one or more ends thereof, at least three monomers each having a (meth) acrylate group, and at least two adhesion enhancers each having a (meth) acrylate group. Since the various components in the photocurable resin composition have a common functional group, the photocurable resin composition allows uniform photocuring, thereby improving overall properties such as viscosity, surface viscosity, rapid curing, moisture-proof insulation, reliability, and bonding strength.

[0074] In one embodiment, the photocurable resin composition can be prepared by preparing a urethane oligomer and mixing the urethane oligomer, monomer and photoinitiator, and then curing the resulting mixture at a wavelength of about 365 nm. Preferably, the urethane oligomer, monomer and photoinitiator are further mixed with an adhesion enhancer, more preferably with an adhesion enhancer and a defoamer.

[0075] Example 1

[0076] 1) Preparation of oligomer A

[0077] A double-terminal hydroxyl-terminated hydrogenated polybutadiene (hereinafter referred to as HTHPB-1500) having an average weight average molecular weight of about 1500 g / mol, 2-butyl-2-ethyl-1,3-propanediol (BEPD), a diluent (IBOA) and a polymerization inhibitor (BHT) were placed in a reactor and stirred at a temperature of about 40°C.

[0078] Thereafter, isophorone diisocyanate (IPDI) and a reaction catalyst (DBTL) were further added to the resulting mixture in sequence and stirred together with the resulting mixture, and then the resulting mixture was stirred to react while the temperature of the reactor was raised to about 85° C. After confirming the formation of a urethane bond between the polyol and the isocyanate as a primary reaction by FT-IR, the reaction was terminated.

[0079] 2-HEA as a terminal monomer was added to the obtained mixture, and then a secondary reaction was performed while the obtained mixture was stirred. The urethane oligomer A prepared by the secondary reaction was confirmed by FT-IR analysis.

[0080] The molar ratio of HTHPB-1500:BEPD:IPDI:2-HEA is 1:1:3:2, and the diluent is present in the composition including HTHPB-1500, BEPD, IPDI and the diluent in an amount of about 25 wt%.

[0081] Oligomer A had a weight average molecular weight of 7,503 g / mol, and a viscosity of about 9,717 cP (at 55°C).

[0082] 2) Preparation of resin composition

[0083] Isodecyl acrylate (IDA) and isobornyl acrylate (IBOA) were added as monofunctional acrylate monomers, pentaerythritoltriacrylate (PETA) was added as a trifunctional acrylate monomer, and pentaerythritoltetraacrylate (PETRA) was added as a tetrafunctional acrylate monomer.

[0084] 2-(4-methylbenzyl)-2-(dimethylamino)-1-(4-morpholinophenyl)butan-1-one (photoinitiator A-1) was used as a photoinitiator, 4-acryloylmorpholine (hereinafter referred to as Additive A), 3-(trimethoxysilyl)propyl acrylate (hereinafter referred to as Additive B) and 3-glycidoxypropyltriethoxysilane (hereinafter referred to as Additive C) were used as adhesion enhancers, and a silicone-based defoamer was used as a defoamer. Additive B and Additive C were used in the same amount.

[0085] The resin composition was prepared by adding the above-mentioned monomer, photoinitiator and additives (adhesion enhancer and defoamer) to oligomer A, followed by stirring. The content of each of the components is listed in Table 1 in % by weight.

[0086] Example 2

[0087] A resin composition was prepared in the same manner as in Example 1, except that oligomer C was used.

[0088] Oligomer C was prepared using HTHPB-2000 (a hydrogenated polybutadiene terminated with hydroxyl groups at both ends having a weight average molecular weight of about 2,000 g / mol) instead of HTHPB-1500, and the content of the photoinitiator was increased by 3 / 2 times while reducing the content of IBOA to have the same total weight as in Example 1.

[0089] Oligomer C had a weight average molecular weight of 8,321 g / mol, and a viscosity of about 9,160 cP (55° C.).

[0090] Example 3

[0091] A resin composition was prepared in the same manner as in Example 1, except that 2-benzyl-2-(dimethylamino)-4′-morpholinobutyrophenone (photoinitiator A-2) was used as a photoinitiator and the content of the photoinitiator was increased by 3 / 2 times while reducing the content of IBOA to have the same total weight as in Example 1.

[0092] Example 4

[0093] A resin composition was prepared in the same manner as in Example 1, except that the content of the photoinitiator was increased by 3 / 2 times while the content of IBOA was reduced to have the same total weight as in Example 1.

[0094] Comparative Example 1

[0095] A resin composition was prepared in the same manner as in Example 2 except that oligomer B was used.

[0096] For oligomer B, HTHPB-2000 was used alone instead of HTHPB-2000 and BEPD, and the molar ratio of HTHPB-2000:IPDI:2-HEA was 1:2:2. In the composition including HTHPB-2000, IPDI, 2-HEA and diluent, the diluent was present in an amount of about 28 wt%.

[0097] Oligomer B had a weight average molecular weight of 10,148 g / mol, and a viscosity (55° C.) of about 2,687 cP.

[0098] Comparative Example 2

[0099] A resin composition was prepared in the same manner as in Example 3, except that monoacylphosphinodiphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (photoinitiator B) was used as a photoinitiator.

[0100] Comparative Example 3

[0101] A resin composition was prepared in the same manner as in Comparative Example 2, except that bisacylphosphinophenylbis(2,4,6-trimethylbenzoyl)phosphine oxide (photoinitiator C) was used as a photoinitiator.

[0102] Comparative Example 4

[0103] A resin composition was prepared in the same manner as in Example 1, except that the content of the photoinitiator was reduced by 3 / 2 times while the content of IBOA was increased to have the same total weight as in Example 1.

[0104] Comparative Example 5

[0105] A resin composition was prepared in the same manner as in Example 1, except that 2,4-diethyl-9H-thioxanthen-9-one (photoinitiator D) was further added as a photoinitiator while reducing the content of IBOA to have the same total weight as in Example 1.

[0106] Comparative Example 6

[0107] A resin composition was prepared in the same manner as in Comparative Example 5, except that an additional surface adhesion enhancer was used instead of the photoinitiator D.

[0108] Comparative Example 7

[0109] A resin composition was prepared in the same manner as in Example 4, except that the content of IBOA was increased to have the same total weight as in Example 4 without using Additive B and Additive C.

[0110] The abbreviations and contents (weight %) of the components used in Examples 1 to 4 and Comparative Examples 1 to 7 are listed in Table 1.

[0111] Table 1

[0112]

[0113] Experimental Example 1. Evaluation of viscosity related to processability

[0114] It was examined whether the resin compositions of Examples 1 to 4 and Comparative Examples 1 to 7 had a viscosity suitable for the process.

[0115] The viscosity of each of the resin compositions of Examples 1 to 4 and Comparative Examples 1 to 7 at 25° C. was measured using DV2T (Brookfield Co., Ltd.).

[0116] The results show that each of the resin compositions of Examples 1 to 4 has a viscosity of about 600 ± 10 cP, which is suitable for the process. However, it can be seen that the resin composition of Comparative Example 1 has a too low viscosity of about 361 cP, which indicates very poor processability. The reason behind this result is that only one type of HTHPB-2000 is used in the preparation of oligomer B, resulting in a much lower viscosity than oligomer A or B.

[0117] Experimental Example 2: Evaluation of surface stickiness related to processability

[0118] The surface tack after curing of each of the resin compositions of Examples 1 to 4 and Comparative Examples 1 to 7 was evaluated using a TXATM texture analyzer (universal testing machine, Yeonjin Co., Ltd.).

[0119] By using LED 365nm lamp at 350mJ / cm 2 Each of the resin compositions of Examples 1 to 4 and Comparative Examples 1 to 7 was cured at a dosage of 200 (±20) μm to prepare a sample.

[0120] The surface tack of the samples prepared from the cured resin composition was evaluated using the loop tack method. Specifically, each sample was fixed to the analyzer, and the ring of the analyzer was pressed against the sample (compression, speed: 0.5 mm / s, force: 2 N), and then the maximum load (tension, speed: 0.5 mm / s) when the ring was completely separated from the sample was measured. The results are shown in Table 2.

[0121] The results show that the resin compositions of Examples 1 to 4 have a surface viscosity of 0.6 MPa or less, and specifically, the resin compositions of Examples 3 and 4 have a surface viscosity of about 0.32 MPa or less, indicating that the surface viscosity is significantly reduced, thereby ensuring much better performance than the resin composition of the comparative example. The resin compositions of Comparative Examples 1, 5, 6, and 7, which exhibit surface viscosity similar to that of the resin composition of the example, have very poor overall performance due to extremely low viscosity, insufficient bonding strength, slightly low deep curing rate, or extremely poor thermal shock reliability.

[0122] Experimental Example 3. Evaluation of deep cure rate associated with fast cure properties

[0123] The deep curing rate of each of the resin compositions of Examples 1 to 4 and Comparative Examples 1 to 7 was measured using a Cary 600 FT-IR spectrometer (Agilent Co., Ltd.).

[0124] By using LED 365nm lamp at 350mJ / cm 2 Each of the resin compositions of Examples 1 to 4 and Comparative Examples 1 to 7 was cured at a dosage of 200 (±20) μm to prepare a sample.

[0125] For each sample, the curing rate was calculated based on the difference in peak intensity of the functional group before and after curing. The results are shown in Table 2.

[0126] The results show that the resin compositions of Examples 1 to 4 have a deep curing rate of about 91% or more, preferably about 94.5% or more, and more preferably about 95% or more. The resin compositions of Comparative Examples 1 to 3, 6, and 7, which exhibited similar deep curing rates to the examples, had very poor overall performance due to extremely low viscosity, extremely high surface tack, insufficient bonding strength, or extremely poor thermal shock reliability.

[0127] Experimental Example 4: Evaluation of moisture permeability related to moisture-proof insulation

[0128] The moisture permeability of the resin compositions of Examples 1 to 4 and Comparative Examples 1 to 7 was examined using PERMATRAN-W MODEL 700 (Mocon Co., Ltd.).

[0129] By using LED 365nm lamp at 350mJ / cm 2 Each of the resin compositions of Examples 1 to 4 and Comparative Examples 1 to 7 was cured at a dosage of 200 (±20) μm to prepare a sample.

[0130] For each sample, moisture permeability was measured under the conditions of 38±2° C., 100% relative humidity (RH), and 10 cycles.

[0131] The results show that the resin composition of the example has a 4 to 5 g m 2 / day, preferably 4.5gm 2 / day or less than 4.5gm 2 The resin compositions of Comparative Examples 2 to 7 showing similar moisture permeability to that of the examples had very poor overall performance due to extremely high surface tack, insufficient bonding strength, slightly low deep curing rate, or extremely poor thermal shock reliability.

[0132] Experimental Example 5. Evaluation of migration related to moisture-proof insulation

[0133] Migration of indium tin oxide (ITO) electrodes refers to a phenomenon in which dendritic metal precipitation is generated when a high voltage is applied between electrodes, resulting in undesired connection or disconnection between the electrodes, and may occur when the cured resin has low water and moisture resistance or low bonding strength.

[0134] Migration of the resin compositions of Examples 1 to 4 and Comparative Examples 1 to 7 was examined using SIR13mini (Etac Co., Ltd.) and WiseCube WTH-E programmable humidity chamber (Daihan Co., Ltd.) as a constant temperature / humidity chamber.

[0135] Each of the resin compositions of Examples 1 to 4 and Comparative Examples 1 to 7 was coated on a substrate (ITO glass) to have a thickness of 200 (±20) μm by bar coating, and then heated to 350 mJ / cm 3 using a 365 nm LED lamp. 2 The samples were prepared by curing with a dosage of .

[0136] For each sample, the occurrence of migration was examined under the measurement conditions of 15V, 85°C / 85% and 500 hours. Specifically, each sample was applied to a substrate on which an electrode was deposited, and then the deformation of the electrode due to the migration phenomenon was observed. The results are shown in Table 2.

[0137] The results show that all the resin compositions of Examples and Comparative Examples did not allow migration to occur.

[0138] Experimental Example 6: Evaluation of moisture absorption rate related to moisture-proof insulation

[0139] In order for the resin composition to have good moisture insulation after curing, it is desirable that the resin composition prevents moisture penetration and has little tendency to absorb moisture.

[0140] By applying each of the resin compositions of Examples 1 to 4 and Comparative Examples 1 to 7 to a size of 25 mm×25 mm and a thickness of about 2 mm, and then using a metal 2 or greater than 3,000mJ / cm 2 The samples were prepared by curing with a dosage of .

[0141] Each sample was immersed in distilled water for about 24 hours, and the weight change rate was calculated. The moisture absorption rate was calculated according to the following equation, and the results are shown in Table 2.

[0142] Moisture absorption rate (%) = [(sample weight after immersion in distilled water - initial sample weight) / initial sample weight] × 100 (%)

[0143] The results show that all the resin compositions of Examples have a moisture absorption rate of 0.25% or less. The resin compositions of Comparative Examples 1 to 3 and Comparative Examples 5 to 7, which exhibit moisture permeabilities similar to those of Examples, have very poor overall performance due to extremely low viscosity, extremely high surface tack, insufficient bonding strength, slightly low deep curing rate, or extremely poor thermal shock reliability.

[0144] Experimental Example 7. Evaluation of the reliability of thermal shock resistance

[0145] After applying heat shock to each of the resin compositions of Examples 1 to 4 and Comparative Examples 1 to 7, any change in appearance such as expansion or cracking was examined using TSE-11 (Espec Co., Ltd.).

[0146] Each of the resin compositions of Examples 1 to 4 and Comparative Examples 1 to 7 was deposited on a glass substrate using a dispenser, and then irradiated with a 365 nm LED lamp at 350 mJ / cm 2 The samples were prepared by curing with a dosage of .

[0147] Each sample was subjected to 100 cycles of testing, in which the sample was placed at -40°C and then at 100°C, left at each temperature for 30 minutes (e.g., left at -40°C for 30 minutes and then at 100°C for 30 minutes), and then evaluated for any changes in appearance, such as expansion or cracking. The results are shown in Table 2.

[0148] The results showed that, except for the resin composition of Comparative Example 7, the resin compositions did not suffer any changes in appearance such as swelling or cracking.

[0149] Experimental Example 8: Evaluation of bonding strength

[0150] The post-curing bonding strength of the resin compositions of Examples 1 to 4 and Comparative Examples 1 to 7 was examined using a TXATM texture analyzer (universal testing machine, Enshin Co., Ltd.).

[0151] Each of the resin compositions of Examples 1 to 4 and Comparative Examples 1 to 7 was deposited on a glass substrate using a dispenser, and then irradiated with a 365 nm LED lamp at 350 mJ / cm 2 The samples were prepared by curing with a dosage of .

[0152] The 180° peel strength of each sample was evaluated and the results are shown in Table 2.

[0153] The results show that the resin compositions of Examples 1 to 4 have a bonding strength of about 265 N / m or more, and in particular, the resin compositions of Examples 3 and 4 exhibit a strong bonding strength of about 300 N / m or more. The resin compositions of Comparative Examples 1 and 3, which exhibit similar levels of bonding strength, have very poor overall performance due to extremely low viscosity or high surface viscosity.

[0154] Table 2

[0155]

[0156] Although some embodiments have been described herein, it will be apparent to those of ordinary skill in the art that various modifications, changes, variations, and equivalent embodiments may be made without departing from the spirit and scope of the invention.

Claims

1. A photocurable resin composition comprising: a urethane oligomer, a monomer having at least one unsaturated bond, and a photoinitiator, wherein the urethane oligomer is prepared by reacting a polyol with a polyisocyanate, The polyol comprises at least two types of polyols, The urethane oligomer includes a (meth)acrylate group at one or more terminals thereof, and at least one of the monomers includes a (meth)acrylate group. 2 . The photocurable resin composition according to claim 1 , wherein the photoinitiator comprises an aminoketone compound. 3 . The photocurable resin composition according to claim 1 , wherein the polyol comprises at least one polyol having a weight average molecular weight of 1,000 g / mol or more and at least one polyol having a weight average molecular weight of less than 1,000 g / mol.

4. The photocurable resin composition according to claim 1, wherein the urethane oligomer is prepared by mixing at least two types of polyols with a polymerization inhibitor to prepare a mixture, and then adding a polyisocyanate to the mixture to react with the mixture.

5. The photocurable resin composition according to claim 1, wherein the urethane oligomer is prepared by reacting a polyol, a polyisocyanate and a blocking monomer, and The molar ratio of the polyol, the polyisocyanate and the end-capping monomer is in the range of N:N+1:2 or N+1:N:2, wherein N is a natural number of 1 to 10. 6 . The photocurable resin composition according to claim 3 , wherein a molar ratio of the polyol having a weight average molecular weight of 1,000 g / mol or more to the polyol having a weight average molecular weight of less than 1,000 g / mol is in the range of 3:1 to 1:

3. 7 . The photocurable resin composition according to claim 1 , wherein the monomer has at least one functional group and comprises at least two types of monomers. 8 . The photocurable resin composition according to claim 7 , wherein the monomer comprises at least one (meth)acrylate group. 9 . The photocurable resin composition according to claim 1 , wherein the photoinitiator comprises an α-amino ketone compound.

10. The photocurable resin composition according to claim 1, wherein the photoinitiator comprises at least one selected from the group consisting of 2-benzyl-2-(dimethylamino)-4′-morpholinobutyrophenone and 2-(4-methylbenzyl)-2-(dimethylamino)-1-(4-morpholinophenyl)butan-1-one.

11. The photocurable resin composition according to claim 1, further comprising: At least one selected from the group consisting of an adhesion enhancer, a surface tack enhancer, and a defoaming agent.

12. The photocurable resin composition according to claim 1, further comprising: Adhesion enhancers, wherein the urethane oligomer is present in an amount of 40 parts by weight to 60 parts by weight, The monomer is present in an amount of 35 to 60 parts by weight, The photoinitiator is present in an amount of 0.1 to 10 parts by weight, and The adhesion enhancer is present in an amount of 1 to 3 parts by weight.

13. A method for preparing a photocurable resin composition, comprising: The urethane oligomer, monomer and photoinitiator are mixed. The urethane oligomer is prepared by mixing at least two types of polyols with a polymerization inhibitor to prepare a mixture, adding polyisocyanate to the mixture to react with the mixture, and adding a terminal monomer to the reaction mixture to react with the reaction mixture. 14 . The method for preparing a photocurable resin composition according to claim 13 , wherein a diluent is further added when the polyol and the polymerization inhibitor are mixed.

15. The method for preparing a photocurable resin composition according to claim 13, wherein The polyol comprises a mixture of a polyol having a weight average molecular weight of 1,000 g / mol or more and a polyol having a weight average molecular weight of less than 1,000 g / mol, and A molar ratio of the polyol having a weight average molecular weight of 1,000 g / mol or more to the polyol having a weight average molecular weight of less than 1,000 g / mol is in a range of 3:1 to 1:3.

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