KR101142804B1 - Ultraviolet Hardening Polyurethane Adhesive Making Method - Google Patents

Abstract

The present invention relates to a method for producing an ultraviolet curable polyurethane adhesive, in particular the ultraviolet curable polyurethane adhesive prepared by the present invention is 40 to 70% by weight polyurethane acrylate oligomer, 25 to 55% by weight acrylate monomer, photoinitiator 0.1 to 5% by weight, including an adhesion promoter 0.05 to 10% by weight, there is an effect that can bond the liquid crystal display device and the window without optical loss.

Description

Ultraviolet Hardening Polyurethane Adhesive Making Method

The present invention relates to a method for manufacturing an ultraviolet curable polyurethane adhesive, and more particularly, to a method for manufacturing an ultraviolet curable polyurethane adhesive capable of adhering a liquid crystal display device and a window without optical loss.

Liquid crystal displays (LCDs) are widely used in electronic products having display devices, such as computers, televisions, mobile phones, and digital cameras, because of their advantages such as light weight, thin thickness, and relatively low power consumption.

Conventionally, an optical tape was mainly used to bond a liquid crystal display device and a window, and an ultraviolet curable silicone adhesive or an ultraviolet curable pressure sensitive adhesive was attempted.

In the process of using optical tape, the yield of the tape is low because the peeling and attaching process of the tape is not automated and the probability of defects in the process is high. In addition, when the tape is used, the air layer is formed, light scattering occurs due to the low refractive index of the air layer, and the visibility and contrast ratio are reduced, resulting in high optical loss and condensation of water in the air layer formed by the temperature change. There is a problem, and there is a disadvantage that inhibits the thinning as much as the thickness of the air layer. In addition, in the high temperature or high temperature and high humidity environment, there is an environmental problem that the adhesion strength is reduced sharply due to the decrease in cohesion.

In order to overcome this problem, the use of an ultraviolet curable silicone adhesive and an ultraviolet curable pressure sensitive adhesive has been attempted in the adhesion of a liquid crystal display device and a window.

In the case of the ultraviolet curable silicone adhesive, it is difficult to obtain high productivity and low adhesive strength because additional heat is required after UV irradiation is preceded.

In addition, in the case of UV-curable pressure-sensitive adhesive, since the polymerized copolymer (Co-polymer) is used, the curing rate by UV light is slightly slower than when using general polyurethane and epoxy series, and the two substrates are sticky. Since the adhesive strength is low at room temperature, in particular, in the high temperature or high temperature and high humidity environment, there is a disadvantage in that the adhesion force due to the cohesion decrease of the copolymer is sharply reduced.

In the case of bonding using the ultraviolet curable silicone adhesive, the ultraviolet curable pressure sensitive adhesive, or the optical tape 120, the window 110 may be closed by the case as shown in FIG. 1 due to the weak adhesive force between the liquid crystal display device 130 and the window 110. Overlapping structures are preferred. This structure can compensate for the problems caused by the weakened adhesion, but it can act as a factor that limits the various designs of the final product and inhibits slimming.

Due to the above problems, optical tapes having a relatively easy process than UV-curable silicone adhesives and UV-curable adhesives have many disadvantages and are widely used.

In order to overcome these problems, the use of an ultraviolet curable polyurethane adhesive in the adhesion of the liquid crystal display device and the window can be considered. In general, the adhesive strength of the polyurethane adhesive is superior to the pressure-sensitive adhesive consisting of a silicone adhesive, a copolymer. This is largely due to the high cohesion of the adhesive itself. Moreover, the adhesion in high temperature or high humidity environments is also excellent.

However, the refractive index of the cured UV curable polyurethane adhesive should be about 1.52, which is the refractive index of glass or plastic used as a window, so that optical loss due to light refraction and scattering does not occur. However, polyurethane acrylate oligomers and acrylate monomers, which are generally used in UV curable polyurethane adhesives, have a refractive index of 1.48 or less. Although some acrylate monomers have high refractive index, most of them have difficulty in use because they have low adhesion to the substrate and high shrinkage. In addition, although epoxy acrylate oligomer and epoxy acrylate monomer having high refractive index exist, high refractive index can be obtained by applying it, but it is a structural characteristic of epoxy. The high shrinkage may cause deformation in the liquid crystal display device and the window, and the biggest problem is that the adhesion to the two substrates is significantly low, making it difficult to apply.

Due to these problems, UV-curable polyurethane adhesives are not used to bond the liquid crystal display device and the window.

The present invention has been made to solve the above-mentioned problems of the prior art, the object of the present invention is to provide a method for producing a UV curable polyurethane adhesive having a refractive index close to 1.52 and excellent in high processing speed and adhesion.

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UV-curable polyurethane adhesive production method according to the present invention is a polyurethane acrylate oligomer 40 to 70% by weight, acrylate monomer 25 to 55% by weight, photoinitiator 0.1 to 5% by weight, adhesion promoter 0.05 to 10% by weight It is configured to include.

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The UV curable polyurethane adhesive prepared by the UV curable polyurethane adhesive production method according to the present invention configured as described above has a high curing rate, a low shrinkage rate, and a refractive index of 1.52, which is excellent in adhesion to a substrate. Therefore, there is an advantage that can be used to bond the liquid crystal display device and the window while overcoming the disadvantages of the conventional optical tape, ultraviolet curable silicone adhesive, ultraviolet curable pressure sensitive adhesive.

1 is a cross-sectional view showing a state of bonding the window and the liquid crystal display device according to the prior art.
Figure 2 is a cross-sectional view showing a state of bonding the window and the liquid crystal display device using the ultraviolet curable polyurethane adhesive prepared by the ultraviolet curable polyurethane adhesive manufacturing method according to the present invention.
Figure 3 is a flow chart showing a liquid crystal display device bonding method using the ultraviolet curable polyurethane adhesive prepared by the method for producing an ultraviolet curable polyurethane adhesive according to the present invention.

Hereinafter, with reference to the accompanying drawings an embodiment of a method of manufacturing a UV-curable polyurethane adhesive and a liquid crystal display device bonding method using the same according to the present invention will be described in detail.
Figure 2 is a cross-sectional view showing a state of bonding the window and the liquid crystal display device using the ultraviolet curable polyurethane adhesive prepared by the method for producing a UV-curable polyurethane adhesive according to the present invention, Figure 3 is an ultraviolet curable type according to the present invention A flowchart showing a method of adhering a liquid crystal display device using an ultraviolet curable polyurethane adhesive prepared by a method of preparing a polyurethane adhesive.

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Figure 2 is a cross-sectional view showing a state of bonding the window and the liquid crystal display device using the ultraviolet curable polyurethane adhesive prepared by the method of manufacturing an ultraviolet curable polyurethane adhesive according to the present invention. Referring to FIG. 2, the window 110 is adhered to the liquid crystal display device 130 by an ultraviolet curable polyurethane adhesive 121. The case 141 which is in contact with the edge portion of the entire outer shell without covering the window 110 is assembled.

Most of the window 110 is made of plastic or glass. Among them, polymethylmethacrylate (PMMA) is most used because it most satisfies optical and physical properties, and when scratch resistance is required, it is preferable to be made of glass.

Figure 3 is a flow chart showing a liquid crystal display device bonding method using the ultraviolet curable polyurethane adhesive prepared by the method for producing an ultraviolet curable polyurethane adhesive according to the present invention. Referring to FIG. 3, an ultraviolet curable polyurethane adhesive 121 is applied to the window 110 (S11). Then, the liquid crystal display device 130 is stacked on the window 110 (S12). Ultraviolet rays are irradiated thereto to temporarily harden the ultraviolet curable polyurethane adhesive 121 (S13). Next, the window 110 and the liquid crystal display device 130 laminated by the ultraviolet curable polyurethane adhesive 121 are cleaned (S14). Ultraviolet rays are irradiated here again to cause the ultraviolet curable polyurethane adhesive 120 to harden (S15).

In the above-described step S13, the wavelength of the ultraviolet ray that temporarily cures the ultraviolet curable polyurethane adhesive 121 is 250 nm to 440 nm, and the amount of light is preferably 1,000 mJ / cm 2 or less in which all of A, B, C, and V wavelengths are added together. When the amount of light exceeding 1,000 mJ / cm 2 is irradiated, the curing density rises and the reworkability decreases.

In the above-described step S15, the wavelength of the ultraviolet rays which harden the ultraviolet-curable polyurethane adhesive 121 to the main curing is 250 nm to 440 nm, and the amount of light is preferably 20,000 mJ / cm² or less in which all of the A, B, C, and V wavelengths are added together. . If the amount of light exceeding 20,000mJ / cm² is irradiated, the substrate may be damaged due to heat and overcuring generated during ultraviolet irradiation.

Hereinafter, the manufacturing method of the ultraviolet curable polyurethane adhesive used for this invention is described in detail.

UV-curable polyurethane adhesive prepared by the method for producing a UV-curable polyurethane adhesive according to the present invention is polyurethane acrylate oligomer 40 to 70% by weight, acrylate monomer 25 to 55% by weight, photoinitiator 0.1 to 5% by weight, It comprises 0.05 to 10% by weight of adhesion promoter.

The polyurethane acrylate oligomer included in the UV curable polyurethane adhesive may include a step of activating a polyol by mixing and reacting a polyol and an acrylate monomer in a reactor, and adding and mixing a diisocyanate into the reactor to prepare a urethane prepolymer. ) And a acrylate monomer capable of reacting with the urethane prepolymer synthesized to react with radicals generated from the photoinitiator decomposed by ultraviolet rays is introduced into the reactor to introduce a double bond at the end. Synthesized linear polyurethane acrylate oligomers. At this time, 1 to 2 moles of acrylate monomers are added to 1 mole of urethane prepolymer.

The acrylate monomer capable of reacting with the urethane prepolymer in the reaction is 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxy Preference is given to using either propyl methacrylate or 2-hydroxybutyl methacrylate.

Examples of the diisocyanate include isophorone diisocyanate, 2,4-toluene diisocyanate and isomers thereof, hexamethylene diisocyanate, 2,2-bis-4'-propane isocyanate, 6-isopropyl-1,3-phenyl diisocyanate , 1,6-hexanediisocyanate, 4,4'-biphenylene diisocyanate, 3,3'-dimethylphenylene diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, p- Phenylene diisocyanate, m-phenylene diisocyanate, 1,5-naphthalene diisocyanate, 1,4-xylene diisocyanate, 1,3-xylene diisocyanate, isophorone diisocyanate, 1,5-naphthalene diisocyanate, 1 Preference is given to using one of, 4-xylene diisocyanate and 1,3-xylene diisocyanate.

The polyol has the greatest influence on optical properties such as the physical properties and refractive index of the polyurethane acrylate oligomer. Since the structure of the synthesized polyurethane acrylate oligomer is most preferably linear, the polyol used is preferably in the form of a diol. In addition, since the polyol is used where high transparency and refractive index are required, the polyol requires a refractive index of 1.55 or more and a light transmittance of 95% or more. Even more preferred is the use of fluorene.

Structural formula of the polyol is represented by the formula (1) below.

[Formula 1]

The structural formula of the urethane prepolymer synthesized using the polyol having the structure of [Formula 1] is the same as [Formula 2]. In Formula 2 n is an integer of 2 to 7, R1 is depending on the diisocyanate used. When n is an integer of 2-7, the number of urethane group bonds of a urethane prepolymer becomes 6-16 pieces. When the number of urethane group bonds is less than 6, the curing density of the final composition is increased to increase hardness and shrinkage after curing, which may cause deformation of the adhesive base and reduction of adhesive strength, and various viscosity of the final composition becomes difficult due to low viscosity. In addition, when the number of urethane group bonds exceeds 16, a substantial high viscosity urethane prepolymer is synthesized. Due to the high viscosity, the operation of reacting the synthesized urethane prepolymer with the acrylate monomer is difficult, and even if prepared, the high viscosity of the final composition is not only difficult to degas, but also causes a decrease in wettability with the substrate, thereby reducing adhesion. In addition, workability is reduced by causing an increase in the input time and the reaction time of the raw material during the preparation of the final composition.

[Formula 2]

The structural formula of the polyurethane acrylate oligomer synthesized using the urethane prepolymer having the structure of [Formula 2] is as shown in [Formula 3]. In Formula 3, m is an integer of 2 to 7, R1 depends on the diisocyanate used, R2 and R3 depends on the acrylate monomer used.

(3)

Among the acrylate monomers included in the ultraviolet curable polyurethane adhesive, monofunctional monomers include diethylaminoethyl acrylate, dimethylaminoethyl acrylate, t-octyl acrylate, N, N-dimethyl acrylamide, N-vinyl caprolactam, N-vinyl pyrrolidone, acryloyl morpholine, isobutoxymethyl acrylamide, diacetone acrylamide, carbonyl (meth) acrylate, isobonyl (meth) acrylate, tricyclotecanyl acrylate, 2-phenoxy Ethyl (meth) acrylate, dicyclopentanyl acrylate, dicyclopentadiene acrylate, methoxypolypropylene glycol acrylate, methoxypolyethylene glycol acrylate, ethoxyethoxyethyl acrylate, methoxyethylene glycol acrylate, Polypropylene Glycol Monoacrylate, Polyethylene Glycol Monoacrylate , Phenoxyethyl acrylate, cyclohexyl acrylate, benzyl acrylate, tetrahydroperfuryl (meth) acrylate, epoxydiethylene glycol acrylate, (meth) acrylic acid, butoxyethyl acrylate, tetrahydrofurfuryl Acrylate, β-methacryloyloxyethylhydrogen salate, styryl acrylate, octadecyl acrylate, lauryl acrylate, undecyl acrylate, isodecyl acrylate, decyl acrylate, nonyl acrylate, la Uryl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl acrylate, octyl acrylate, heptyl acrylate, hexyl acrylate, isoamyl acrylate, pentyl acrylate, t-butyl acrylate, iso Butyl acrylate, amyl acrylate, butyl acrylate, isopropyl Acrylate, propyl acrylate, ethyl acrylate, methyl acrylate, 2-hydroxybutyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 7- One or more of amino-3,7-dimethyloctyl acrylate, N, N-diethyl (meth) acrylamide, N, N'-dimethyl-aminopropyl (meth) acrylate can be used.

The polyfunctional monomers among the ultraviolet curable acrylate monomers include trimethylol propane triacrylate, pentaerythritol triacrylate, ethylene glycol diacrylate, 1,6-hexanediol diacrylate, and tripropylene glycol diacrylate. , Trimethylolpropanetrioxyethyl acrylate, tricyclodecanedimethanol diacrylate and tris (2-hydroxyethyl) isocyanurate diacrylate can be used.

Photoinitiators included in the UV curable polyurethane adhesive include 2,2-dimethoxy-2-phenyl-acetophenone, xanthone, 1-hydroxycyclohexylphenyl ketone, benzaldehyde, anthraquinone, 3-methylacetophenone, 1- (4-isopropyl-phenol) -2-hydroxy-2-methyl propane-1-one, thioxanthone, 4-chlorobenzophenone, 4,4'-dimethoxybenzophenone, 4,4'-diaminobenzo One or more of phenone, benzoin propyl ether, benzoinethyl ether can be used.

These photoinitiators include Micure TPO, PBZ, BP, EPD, DETX, BMS, MS-7, HP-8, CP-4, BK-6 and Ciba Geigy's Irgacure 184, 500, and 1173. , 2959, MBF, 754, 651, 369, 907, 1300, 4265, 819, 819DW, 2022, 2100, 784, 250, Darocure TPO, and the like.

Adhesion promoters used in the UV-curable polyurethane adhesives include vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2- (3,4 epoxychlorohexyl) ethyltrimethoxysilane, and 3-glycidine. Doxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3 -Methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2 (aminoethyl) 3 -Aminopropylmethyldimethoxysilane, N-2 (aminoethyl) 3-aminopropyltrimethoxysilane, N-2 (aminoethyl) 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3 -Aminopropyltriethoxysilane, 3-triethoxysilyl-N- (1,3 di Tyl-butylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N- (vinylbenzyl) -2-aminoethyl-3-amino Propyltrimethoxysilanehydrochloride, 3-chloropropyltrimethoxysilane, 3-mecaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, bis (tri Ethoxysilylpropyl) tetrasulfide, 3-isocyanatopropyltriethoxysilane, and the like, and one or more of them can be used.

[Example]

181.95 g of isobonyl acrylate (CAS No. 5888-33-5), 181.95 g of 2-phenoxyethyl acrylate (CAS No. 48145-04-6) and number average molecular weight in a 3 liter round bottom flask 700.82 g (2 mol) of polyol (CAS No. 3236-71-3) having 350.41 g / mol was added thereto. While stirring this, the temperature was maintained at 90 ° C. and stirred for 2 hours 30 minutes. The reactor temperature was lowered to 50 ° C., and 522.48 g (3 mol) of 2,4-toluene diisocyanate (CAS No. 584-84-9) was slowly added and stirred, and 0.12 g of dibutyltin laurate as a reaction catalyst was stirred. 0.7 g of methylhydroquinone was added as a polymerization inhibitor to control an additional initiation reaction that may be generated by heat during synthesis. When the addition was completed, the temperature of the reactor was maintained at 70 ℃ and stirred for 2 hours.

Next, 232.24 g (2 mol) of 2-hydroxyethyl acrylate (CAS No. 818-77-9) was added slowly, and reaction was advanced. After the addition was completed, the mixture was stirred while maintaining the reaction temperature of 70 ° C. for 2 hours.

It was confirmed by the Fourier transform infrared spectroscopy (FTIR) that the isocyanate group peak of 2270cm ^-1 disappeared, indicating that the reaction was terminated, and the hydroxy group completely reacted with the isocyanate group. As a result of gel permeation chromatography (GPC), it was confirmed that the number average molecular weight of the ultraviolet curable polyurethane oligomer was 1,500 g / mol. When the refractive index was measured using a refractometer, the composite had a refractive index of 1.54 and the refractive indexes of isobornyl acrylate and 2-phenoxyethyl acrylate used in the synthesis were 1.474 and 1.509, respectively. It was confirmed that the refractive index of the urethane oligomer was 1.56. Thus, a linear ultraviolet curable polyurethane oligomer having a number average molecular weight of 1,500 g / mol, an average number of urethane group bonds of 6 and a refractive index of 1.56 was synthesized.

65.00 g of the synthesized polyurethane acrylate oligomer was added to a 0.25 liter blender, 11.00 g of isobornyl methacrylate (CAS No. 7534-94-3) and acryloyl morpholine (CAS No. 5117-12-4 ) 12.00 g, ethoxyethoxyethyl acrylate (CAS No. 7328-17-8) 5.00 g, 2-hydroxyethyl methacrylate (CAS No. 868-77-9) 5.50 g, adhesion promoter 0.25 g, Irgacure 1173 0.75g, Irgacure 2959 0.50g was added to the total weight is 100.00g, it was blended while stirring at 350rpm using a propeller-type stirring blade for 60 minutes at room temperature.

After stirring for 60 minutes, it filtered using the 5 micrometer filter. An ultraviolet curable polyurethane adhesive composition having a viscosity of 2,200 cPs at 25 ° C. was obtained.

Comparative Example 1

In the same manner as in the above embodiment, but by adjusting the reaction ratio of diisocyanate and polyol to prepare a UV curable polyurethane oligomer having a urethane group bond number of 4 to synthesize a UV curable polyurethane adhesive composition. Thus, an ultraviolet curable polyurethane adhesive composition having a viscosity of 1,200 cPs at 25 ° C. was obtained.

Comparative Example 2

Polyurethane acrylate oligomer using polytetramethylene ether glycol (CAS No. 25190-06-1), which is the same method as the above-described embodiment, but is a polyether polyol having a number average molecular weight of 1,000 g / mol instead of a high refractive polyol. And an ultraviolet curable polyurethane adhesive composition. Thus, an ultraviolet curable polyurethane adhesive composition having a viscosity of 2,600 cPs at 25 ° C. was obtained.

Comparative Example 3

Polyurethane acrylate oligomer (CAS No. 36890-68-3) using the same method as the above embodiment, but instead of a high refractive polyol, a polycaprolactone diol having a number average molecular weight of 1,250 g / mol of polyester polyol; An ultraviolet curable polyurethane adhesive composition was synthesized. Thus, an ultraviolet curable polyurethane adhesive composition having a viscosity of 3,400 cPs at 25 ° C. was obtained.

[Comparative Example 4]

40.00 g of the polyurethane acrylate oligomer synthesized in the above-described example was added to a 0.25 liter blender, 19.21 g of isobonyl methacrylate, 20.96 g of acryloyl morpholine, 8.73 g of ethoxyethoxyethyl acrylate, and 2 9.60 g of hydroxyethyl methacrylate, 0.25 g of an adhesion promoter, 0.75 g of Irgacure 1173, 0.50 g of Irgacure 2959, and a total weight of 100.00 g were stirred at 350 rpm using a propeller-type stirring blade at room temperature for 60 minutes. Blending.

After stirring for 60 minutes, it filtered using the 5 micrometer filter. An ultraviolet curable polyurethane adhesive composition having a viscosity of 580 cPs at 25 ° C. was obtained.

[Comparative Example 5]

65.00 g of the polyurethane acrylate oligomer synthesized in the above-described example was added to a 0.25 liter compounder, 11.00 g of isobonyl methacrylate, 12.00 g of acryloyl morpholine, and 5.00 g of ethoxyethoxyethyl acrylate. 5.50 g of hydroxyethyl methacrylate, 0.75 g of Irgacure 1173, and 0.50 g of Irgacure 2959 were added thereto, and the total weight thereof was 99.75 g. The mixture was stirred at 350 rpm using a propeller type stirring blade at room temperature for 60 minutes.

After stirring for 60 minutes, it filtered using the 5 micrometer filter. An ultraviolet curable polyurethane adhesive composition having a viscosity of 2,200 cPs at 25 ° C. was obtained.

[Adhesion measurement 1]

Specimens are manufactured and evaluated according to ASTM (American Society for Testing Materials) D1002. Apply UV curable adhesive at 0.5 inch long and 1 inch wide at one end of the glass specimen, then crimp one end of the PMMA specimen and irradiate it in the direction of the PMMA specimen to bond the specimen. The glass specimen shall be 4 inches long and 1 inch wide. The test is carried out 12 times and the average value of 10 times excluding the highest and lowest values is used. Refer to ASTM D1002 for details on how to evaluate adhesion.

[Adhesion Measurement 2]

Proceed in the same manner as in the adhesive force measurement 1 described above. Use glass specimens instead of PMMA specimens.

Hardness Measurement

The UV curable polyurethane adhesive composition was formed using a bar coater (Bar coater) to form a coating film having a thickness of 50㎛ and then cured to a light amount of 3,000mJ / cm2. Using an infrared spectrometer, the degree of cure was measured by comparing the size of a spectral peak of 1435 cm < -1 >

[Environmental Resistance Evaluation 1]

The UV curable polyurethane adhesive composition was used to apply an adhesive with a thickness of 100 μm to bond two glasses, and then the mixture was left to stand at a temperature of 60 ° C. and a humidity of 95% for 96 hours. After drying at room temperature for 2 hours, the penetration of water and the presence of adhesive deformation were observed using a microscope.

[Environmental Evaluation 2]

After the adhesive is applied to a thickness of 100 μm using an ultraviolet curable polyurethane adhesive composition to bond two pieces of glass, the glass is left at a temperature of 80 ° C. for 96 hours. After drying for 2 hours at room temperature, the presence of deformation of the adhesive using a microscope.

[Environmental Evaluation 3]

After the adhesive is applied to a thickness of 100 μm using an ultraviolet curable polyurethane adhesive composition to bond two pieces of glass, it is left for 96 hours at a temperature of −20 ° C. After drying for 2 hours at room temperature, the presence of deformation of the adhesive using a microscope.

[Refractive index measurement]

The refractive index is measured using a refractometer.

[Shrinkage Rate Measurement]

In accordance with Korean Industrial Standards KSM 0004 and KSM 0602, the specific gravity of liquid phase and solid phase of UV-curable polyurethane adhesive is measured, and the volumetric shrinkage rate is measured using the difference between the two values. The measurement formula is as follows.

[Equation 1]

Measurement results of the adhesion, the degree of cure, the environmental resistance, the refractive index, and the shrinkage rate of the Examples and the Comparative Examples are shown in Table 1 below.

Item Example Comparative example One 2 3 4 5 Polyurethane acrylate oligomer (Example) (g)
Polyurethane acrylate oligomer (Comparative Example 1) (g)
Polyurethane acrylate oligomer (Comparative Example 2) (g)
Polyurethane acrylate oligomer (Comparative Example 3) (g)
Isobonyl methacrylate (g)
Acrylic Morpholin (g)
Ethoxyethoxyethyl acrylate (g)
Hydroxyethyl methacrylate (g)
Adhesion Promoter (g)
Photoinitiator Irgacure 1173 (g)
Photoinitiator Irgacure 2959 (g) 65

-

-

-

11
22
5
5.5
0.25
0.75
0.5 -

65

-

-

11
12
5
5.5
0.25
0.75
0.5 -

-

65

-

11
12
5
5.5
0.25
0.75
0.5 -

-

-

65

11
12
5
5.5
0.25
0.75
0.5 40

-

-

-

19.21
20.96
8.73
9.60
0.25
0.75
0.5 65

-

-

-

11
12
5
5.5
-
0.75
0.5 Adhesion 1 (Glass-PMMA) (kgf)
Adhesion 2 (Glass-Glass) (kgf)
Hardness (%)
Environmental resistance 1 (high temperature-high humidity) (microscope)
Environmental resistance 2 (high temperature) (microscope)
Environmental resistance 3 (low temperature) (microscope)
Refractive index (20 ℃)
Volume Shrinkage (%) 6
12
over 90
none
none
none
1.52
3 or less 3
8
over 90
none
none
none
1.52
7 or less 6
13
over 90
none
none
none
1.48
5 or less 7
13
over 90
none
none
none
1.48
6 or less 7
14
over 90
none
none
none
1.50
7 or less 6
12
over 90
Occur
Occur
none
1.52
3 or less

As shown in [Table 1], the ultraviolet curable polyurethane adhesive according to the [Example] has a glass-PMMA adhesive strength of 6, a glass-glass adhesive strength of 12, a low shrinkage rate, a refractive index of 1.52, and curing It has a high rate and shows excellent environmental resistance.

In the case of [Comparative Example 1] in which the polyurethane acrylate oligomer having the number of bonds of the urethane group was 4, the other properties were excellent, but the shrinkage rate and the adhesive strength were lower than those of the [Example]. This is a value that may cause a poor adhesion when deformation and bonding of the substrate of the display device due to shrinkage.

[Comparative Example 2] and [Comparative Example 3] in which the polyurethane acrylate oligomer was synthesized using polytetramethyl ether glycol and polycaprolactone diol, the other properties were excellent but the refractive index was lower than that of the examples. Can be. This is a figure not bonded to the optical adhesion of the window and the display device.

In the case of [Comparative Example 4] in which the content of the polyurethane acrylate oligomer was reduced compared to [Example], the wettability increased due to the decrease in viscosity, but the adhesive strength slightly increased compared to [Example], but the refractive index decreased and the shrinkage rate decreased. You can see the increase.

From the comparison between Example 5 and Comparative Example 5, it can be seen that the use of the adhesion promoter can improve the adhesion and prevent the penetration of moisture under conditions of high temperature, high humidity and high temperature.

110: windows
120: UV curable silicone adhesive, UV curable pressure sensitive adhesive or optical tape
121: UV curable polyurethane adhesive
130: liquid crystal display device
140, 141: case

Claims (11)

delete delete delete delete delete Mixing 40 to 70 weight percent polyurethane acrylate oligomer, 25 to 55 weight percent acrylate monomer, 0.1 to 5 weight percent photoinitiator, 0.05 to 10 weight percent adhesion promoter,
Mixing the polyol and the acrylate monomer in a reactor to activate the polyol; Adding a diisocyanate into the reactor to perform a mixed reaction to synthesize a urethane prepolymer; Injecting an acrylate monomer into the reactor to synthesize a polyurethane acrylate oligomer,
The polyol is an ultraviolet curable polyurethane adhesive, characterized in that the material of the general formula (II) below.
General formula (Ⅱ)

delete delete The method of claim 6,
The diisocyanate is isophorone diisocyanate, 2,4-toluene diisocyanate and isomers thereof, hexamethylene diisocyanate, 2,2-bis-4'-propane isocyanate, 6-isopropyl-1,3-phenyl diisocyanate, 1,6-hexanediisocyanate, 4,4'-biphenylene diisocyanate, 3,3'-dimethylphenylene diisocyanate, 3,3'-dimethyl-4,4'-diphenylmethane diisocyanate, p-phenyl Ethylene diisocyanate, m-phenylene diisocyanate, 1,5-naphthalene diisocyanate, 1,4-xylene diisocyanate, 1,3-xylene diisocyanate, isophorone diisocyanate, 1,5-naphthalene diisocyanate, 1, UV-curable polyurethane adhesive, characterized in that one of 4-xylene diisocyanate, 1,3-xylene diisocyanate. delete delete

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