KR101025721B1 - Solvent-free UV curable white ink composition - Google Patents

Abstract

The solvent-free ultraviolet curing white ink composition of the present invention is a solvent-free ultraviolet curing white ink composition comprising an oligomer and a monofunctional or polyfunctional monomer end-modified with an unsaturated group, a white pigment and a photopolymerization initiator, and having a thickness of 20 μm after curing. When it has a reflectance characteristic of 85% or more, it does not cause an environmental pollution problem when applied to an optical film, and is easy to workability that does not cause a problem of flowing or gathering sagging, and reflectance is 85 It is more than%, excellent in durability, fast curing speed, excellent in yellowness, yellowing degree, etc., can be excellently used in the reflective member and the backlight unit.

Ink, reflectivity, backlight

Description

Solvent-free UV curable white ink composition {Non-Solvent Type, UV-Curable White Ink Composition}

The present invention relates to a solvent-free ultraviolet curable white ink composition and a reflective member manufactured using the same.

Recently, display apparatuses, that is, display apparatuses for displaying an image, have been developed according to their use and types, and liquid crystal display apparatuses having excellent performance and functions among various kinds of display apparatuses are widely used.

The liquid crystal display device is one of flat panel display devices widely used at present, and includes a liquid crystal display panel (LCD panel) including two substrates on which electrodes are formed and a liquid crystal layer. Since the liquid crystal display implements an image by using an LCD panel that controls the amount of light coming from the outside, in order to implement the image on the LCD panel, a separate light source for irradiating light, that is, a backlight unit is required.

The backlight unit includes a reflective sheet for transmitting light, an optical sheet including a diffusion plate, a diffusion sheet having a thin film structure, and a prism sheet, and a lamp device for generating light. The development of an optical sheet having a high brightness of high reflectance of the light in the backlight unit is in progress, and a white composition having a function of a high reflectance suitable for this is required.

For example, in an edge type liquid crystal display panel backlight device, a binder and titanium dioxide, zinc sulfide, sulfuric acid are used to produce a high-reflectance, low-hardness reflective sheet to provide a screen with higher brightness for enveloping a straight tube fluorescent lamp. A technique for imparting high brightness to a solvent-dried white paint using inorganic white pigments including barium, aluminum silicate and acrylic beads containing titanium dioxide is disclosed.

On the other hand, in the case of a fluorescent lamp of the lighting fixture is provided with a fluorescent lamp shade that serves as a reflecting plate. At this time, solvent type liquid paint is used among high roughness paint. For example, a technique of providing a coating composition for high roughness having high reflectivity and easy molding by using a high molecular weight polyester resin or the like is disclosed.

As described above, there may be a case where a high illuminance reflector and a reflecting film are provided in various structures including a lighting apparatus, a copying machine, a display device, and the like. The reflecting plate and the reflecting film require high reflectance, surface leveling, yellowing resistance, and workability. Therefore, in consideration of the above elements, there is a need for ink for manufacturing the reflecting plate and the reflecting film.

However, the prior art has to use the solvent as a paint and ink containing a solvent, thereby generating waste water and harmful substances, causing environmental pollution problems, including the risk of poisoning, fire and explosion, there is a safety problem. In addition, there is a problem of forming a sagging (flowing or gathering sagging) is a big constraint also in workability.

The present invention is to solve the above problems, does not cause environmental pollution problems when applied to the optical film, easy to workability that does not occur the problem of forming a sagging (flowing or gathering solvent), the reflectance is 85 It is an object to provide a solvent-free ultraviolet (UV) curable white ink composition of more than%, excellent durability, excellent workability in gravure printing, fast curing speed, and suitable visibility, and a reflective member manufactured using the same. do.

As a means for achieving the above object, the present invention is oligomer end-modified with an unsaturated group; Photopolymerizable monomers; White pigments; A non-solvent type ultraviolet curable white ink composition comprising a photopolymerization initiator, and when the thickness is 20 μm after curing, provides a solvent-free ultraviolet curable white ink composition having a property of 85% or more reflectance.

In the above, at least one or more of a dispersant, a leveling agent, and a stabilizer for improving the dispersibility of the white pigment may be further included.

In addition, the oligomer terminally modified with an unsaturated group comprises a modified epoxy acrylate oligomer having a number average molecular weight of 500 to 1500 and an unsaturated acrylate acrylate oligomer having a number average molecular weight of 1000 to 3000, and 10 to 40 weight of the total content of the composition. It is contained in the range of%, the photopolymerizable monomer is included in the range of 10 to 30% by weight of the total content of the composition as a mixture of an acrylate monomer having an ethoxy functional group and an acrylate monomer having a hexanediol functional group, the white pigment Is rutile titanium dioxide, the average particle diameter is in the range of 0.1 ~ 10㎛, characterized in that included in the range of 40 to 75% by weight of the total content of the composition.

In addition, the photopolymerization initiator uses an ultraviolet initiator having an absorption main peak of 220 nm to 260 nm in ultraviolet / visible light in methanol and an ultraviolet initiator having an absorption main peak of 360 nm to 400 nm in ultraviolet / visible light in methanol. Characterized in that. Alternatively, the photopolymerization initiator is characterized by using two types of ultraviolet initiators having a difference in absorption main peak from methanol to ultraviolet / visible light in the range of 100 nm to 180 nm. As an example, the photopolymerization initiator may be 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (2,4,6-trimethylbenzoyl-diphenyl-phosphineoxide) and 1-hydroxycyclohexylphenylketone. It is characterized in that it is included in the range of 2 to 8% by weight of the total content of the composition.

The present invention also provides a reflecting member and a backlight unit having the reflecting member prepared by applying the non-solvent type ultraviolet curable white ink composition on top of the substrate and curing the same.

Hereinafter, the present invention will be described in more detail. The following description is intended to assist in the understanding of the present invention by describing specific or optimal examples, so that there may be definite or limited expressions, but it is not intended to limit the scope of rights defined by the claims. In this specification, the term "acrylate" is also assumed to include "methacrylate".

Solvent-free UV-curable white ink composition according to an embodiment of the present invention, a non-solvent-type UV-curable white ink composition comprising an oligomer and a monofunctional or polyfunctional monomer terminally modified with an unsaturated group, a white pigment and a photopolymerization initiator, When the thickness is 20㎛, it has a characteristic of having a reflectance of 85% or more.

Hereinafter, each component is demonstrated.

(a) oligomers terminally denatured with unsaturated groups

The oligomers end-modified with the unsaturated group used in the present invention generally use ultraviolet curable resins as photopolymerizable oligomers. For example, as the photopolymerizable oligomer, unsaturated polyester resins, polyfunctional acrylate resins, epoxy acrylic resins, epoxy acrylate resins, urethanes, urethane acrylates, etc. may be used alone or in combination, and the number average molecular weight is in the range of 500 to 5000. It is good to be

More preferably, the oligomer terminally denatured with an unsaturated group comprises a modified epoxy acrylate oligomer having a number average molecular weight of 500 to 1500 and an unsaturated ester acrylate oligomer having a number average molecular weight of 1000 to 3000, and contains 10 to 40 weight of the total content of the composition. It was found that what is included in the% range is very excellent in the degree of curing, workability such as viscosity, yellowness, and the like.

In the present invention, the epoxy acrylate oligomer end-modified with an unsaturated group has a prominent effect of improving the curing rate. For example, commercially available Ebecryl 600, Ebecryl 3700, Ebecryl 3701, Ebecryl 3702 from SK Cytec, PHOTOMETER 3016-LT from Cognis, and PHOTOMETER 3016. The terminally modified epoxy acrylate oligomer has a number average molecular weight of 500 to 1500, it is preferable to use 5% to 20% by weight relative to 100% by weight of the composition of the white ink.

In addition, the unsaturated ester acrylate oligomer in the present invention is excellent in titanium dioxide and wetting (wetting) to increase the input weight percent of titanium dioxide, easy viscosity control, the leveling effect of the surface of the cured product after ultraviolet curing is remarkable. Examples include commercially available Ebecryl 830 from SK Cytec and PHOTOMETER 5010 from Cognis. The unsaturated ester acrylate oligomer has a number average molecular weight of 1000 to 3000, it is preferable to use 5% to 20% by weight relative to 100% by weight of the composition of the white ink.

(b) photopolymerizable monomer

Since the photopolymerizable monomer used in the present invention is used as a diluent for matching the working viscosity with the oligomer terminally modified with the above unsaturated group, a low molecular weight monomer is preferable. Reactive monomers comprising at least one acrylate group, methacrylate group or vinyl group are used in amounts of 10% to 30% by weight relative to 100% by weight of the composition of the white ink. In the present invention, a solvent is not used, and the photopolymerizable monomer used for viscosity control becomes part of the polymer network after curing, thereby preventing environmental pollution due to volatilization, product contamination due to outgassing, and yellowing. It is suitable as a reflecting member of a lighting device such as a backlight unit in a high temperature environment.

The photopolymerizable monomer may have a monomer having one or more acrylate groups, methacrylate groups or vinyl groups in its molecular structure, and having one or three or more various functional groups. In particular, it is desirable to have a low curing shrinkage while having a high tensile strength in the film state. Preferred examples thereof include phenoxyethyl acrylate, phenoxyethylene glycol acrylate, phenoxy tetraethylene glycol acrylate, phenoxy hexaethylene glycol acrylate, isobornyl acrylate (IBOA), isobornyl methacrylate, N-vinyl Pyrrolidone (N-VP), N-vinylcaprolactam (N-VC), Acryloyl Morpholine (ACMO), bisphenol ethoxylate diacrylate, ethoxylate phenol monoacrylate, polyethylene glycol 400 diacrylate (polyethyleneglycol 400 diacrylate), tripropylene glycol diacrylate, trimethyl propane triacrylate (TMPTA), polyethylene glycol diacrylate, ethylene oxide addition type triethyl propane triacrylate (ethyleneoxide-addition triethylolpropantri acrylate; EO-TMPTA), pentaerythritol tetraacrylate (PETA), 1,4-butanediol diacrylate, 1-6hexanediol diacrylate, ethoxylated pentaerythritol tetraacrylate, ethoxylated nonylphenol acrylate, 2-phenoxyethyl acrylate, ethoxylated bisphenol A diacrylate, Alkoxylated nonylphenol acrylates, alkoxylated trifuntional acrylate esters, metallic diacrylates, trifunctional acrylic esters, trifunctional meta Trifuntional methacrylate esters and mixtures thereof.

More preferably, the photopolymerizable monomer in the present invention is a monomer containing an acrylate group containing an ethoxy group to increase adhesion and a monomer containing an acrylate group containing a hexanediol functional group to increase the curing rate. It was found that the use together with the excellent effect.

The monomer containing an acrylate group containing an ethoxy group for increasing the adhesion in the present invention is chemical resistance; Flexibility; Adhesion; Low shrinkage; Wear resistance; It has a property such as impact strength and has a viscosity at 25 ° C. of 50 cPs to 1000 cPs (Brookfield DV III +), and a refractive index of 1.50 or less, preferably 1.44 to 1.48.

The monomer containing an acrylate group having a hexanediol functional group for increasing the curing rate in the present invention has a low viscosity; Low volatility; High hardness after curing; Wear resistance after curing; Thermal stability; Chemical resistance; Water resistance; Adhesion; It has properties such as solubility suitable for free radical ploymerization and has a viscosity at 25 ° C. of 5 cPs to 200 cPs (Brookfield DV III +) and a refractive index of 1.50 or less, preferably 1.42 to 1.48. It is preferable.

(c) white pigment

White pigments are not only used to color white, but also mixed with other colored pigments to match a specific color. Containing concealing power, the white pigment is not only excellent, but also reflectance can be adjusted according to the content of white pigment. Specific examples of white pigments include titanium dioxide (TiO ₂ ), zinc oxide (ZnO), lithopone (ZnS + BaSO ₄ ), lead white (2PbCO ₃ Pb (OH) ₂ ), barium sulfate, calcium carbonate, aluminum oxide, etc. Although these are mentioned, It is not specifically limited. Among these, titanium dioxide with a large concealment improvement effect is preferable. Titanium dioxide is neutral, stable in chemical properties, nontoxic, strong in chemical resistance to acids and alkalis, and the highest in coloration and hiding power. There are rutile and anatase types depending on the crystal structure.

White pigment shows its limitations as its content is increased, but the reflectivity is excellent but the dispersibility, durability and uniformity are inferior. Thus, when the rutile titanium dioxide is used, the problem may be further improved. The rutile type is surface-treated with Al ₂ O ₃ , Sb ₂ O ₃ , ZnO, etc., and it has good dispersibility and gloss and weather resistance. The anatase type has very whitening but excellent whiteness. . The titanium dioxide is a material exhibiting a wavelength of 350 to 590 nm, the reflectance drops sharply when the content is less than 40% by weight based on the total amount of the composition, and when the content exceeds 75% by weight, the workability is deteriorated. Since the weight of the type monomer is relatively low, there is a disadvantage in that the curing performance is poor. Therefore, the content of the titanium dioxide is preferably 40 to 75% by weight. More preferably about 50 to 65% by weight.

In addition, the particle size of titanium dioxide affects the reflectivity, hiding rate, and wetting with oligomers that are end-modified with an unsaturated group. If the average particle diameter is less than 0.1 mu m, the reflectivity and concealability is inferior. If the average particle diameter is 10 mu m or more, the surface becomes uneven after UV curing, and the reflectivity and the concealment are not uniform, and the thickness of the ultraviolet curable is also limited. In addition, the wettability with the oligomers terminally denatured with an unsaturated group depends on the average particle diameter. For example, when the viscosity of the oligomers, photopolymerizable monomers, dispersants, photoinitiators, and photoinitiators having different average particle diameters is 0.32 μm and 0.42 μm titanium dioxide, and the viscosity is measured, the average particle diameter is 0.32 μm. The white ink formulated with titanium has a lower viscosity from 500 cPs to 1500 cPs (Brookfield DV II +) than the white ink formulated with titanium dioxide having an average particle diameter of 0.42 µm. This means that the white ink blended with titanium dioxide having an average particle diameter of 0.32 µm is better in wetting than the white ink blended with titanium dioxide having an average particle diameter of 0.42 µm. Examples include commercially available Du-Pont Ti-Pure R-700, Ti-Pure R-706, Ti-Pure R-900, Ti-Pure R-902, and Ti-Pure R-960. .

The white pigment is preferably used 40 to 75% by weight based on 100% by weight of the composition of the white ink. In addition, in the present invention, the average particle diameter of the white pigment is preferably 0.1 µm to 10 µm, more preferably 0.2 µm to 5.0 µm. In addition, the titanium dioxide average particle size is preferably used in the form of a powder distributed in 0.2 to 5.0 micrometers.

(d) photoinitiators

Photoinitiators used in the present invention, conventional materials, such as commercially available Irgacure # 184 (1-hydroxycyclohexylphenylketone) of Ciba Geigy, divalent Irgacure # 819 (bis 2,4,6-trimethylbenzoyl-phenylphosphineoxide) (Bis (2,4,6-trimethylbenzoyl) -phenylphosphineoxide)), Igacure # 907 (2-methyl-1 [4- (Methylthio) phenyl] -2-morpholino-propane-1-on (2-methyl-1 [4- (methylthio) phenyl] -2-morpholino-propan-1-on)), Igacure # 500 ( Hydroxyketones and benzophenone, Igacure # 651 (benzildimethyl-ketone), Darocure # 1173 (2-hydroxy-2-methyl-1-phenyl-propane-1 -One (2-hydroxy-2-methyl-1-phenyl-propan-1one), Darocure TPO (2,4,6-trimethylbenzoyl-diphenyl-phosphineoxide (2,4,6- trimethylbenzoyl-diphenyl-phosphineoxide)), Darocure CGI # 1800 (bisacylphosphine oxime (Bisacyl phosphine oxide)) and CGI # 1700 can be used at least one selected from (bis-acylphosphine oxide and benzophenone (bisacyl phosphine oxide and hydroxy ketone) group consisting of a).

More preferably, surface hardening and deep hardening are appropriately performed for sufficient ultraviolet curing of the ultraviolet curable white ink. For this purpose, an ultraviolet initiator having an absorption main peak in the ultraviolet / visible ray in methanol is 220 nm to 260 nm so that the surface hardening is appropriate, and an absorption main peak in the ultraviolet / visible ray in methanol so that the deep curing is performed properly. It is preferable to use the ultraviolet initiator whose is 360 nm-400 nm. In addition, the photopolymerization initiator may be preferably used together with an ultraviolet initiator having a difference in absorption main peak in ultraviolet / visible light in methanol of two kinds of photopolymerization initiators.

In addition, the degree of whiteness of the UV curable white ink after UV curing affects not only the color of oligomers, photopolymerizable monomers, and various additives end-modified with an unsaturated group, but also the color of the photoinitiator. Among the photoinitiators, a photoinitiator having a yellowish color serves to lower the whiteness before and after UV curing of the white ink. In particular, since the ultraviolet long wavelength initiator of the photoinitiator affects, the whiteness is affected according to the type and the input content of the photoinitiator.

The photoinitiator of the present invention is 2,4,6-trimethylbenzoyl-diphenyl-phosphineoxide and 1-hydroxy in consideration of the curing rate and whiteness of the ultraviolet curable white ink. Cyclohexyl phenyl ketone (1-hydroxycyclohexylpheylketone) was invented that suitable, the photoinitiator may comprise 2.0 to 10% by weight relative to the total weight of the composition.

Solvent-free UV-curable white ink composition of the present invention is another embodiment, characterized in that further comprises at least one or more of a dispersing agent, leveling agent, and stabilizer to improve the dispersibility of the white pigment in the above-described composition In addition, various additives may be added.

(e) dispersants

The dispersant used in the present invention is not limited, but commercially available by BYK CHEMI DISPERBYK, DISPERBYK-109, DISPERBYK-110, DISPERBYK-111, DISPERBYK-112, DISPERBYK-164, DISPERBYK-168, DISPERBYK-180, DISPERBYK-181 , TEPER Dispers 610, TEGO Dispers 610 S, TEGO Dispers 630, TEGO Dispers 650, TEGO Dispers 651, TEGO Dispers 681 UV, etc. may be used.

The inventors have a phosphate polyester copolymer and a dispersant containing 0.01 to 20 parts by weight of phosphoric acid relative to the copolymer so that inorganic matter of titanium dioxide is not precipitated from organic substances such as oligomers and photopolymerizable monomers which are end-modified with unsaturated groups. It has been found that the use is superior to other commercially available dispersants. In particular, the dispersant is more liquid at room temperature to more effectively exhibit the dispersing properties in the composition of the present invention that is a solvent-free. The dispersant further improves the whiteness in terms of visibility and maximizes reflection efficiency as well as preventing precipitation of titanium dioxide. The dispersant is preferably used 0.5% to 3% by weight based on 100% by weight of the composition of the white ink.

(f) other additives

In addition, the ultraviolet curable white ink composition of the present invention, in addition to the components described above, in order to improve thermal and oxidative stability, storage stability, surface properties, flow characteristics and process characteristics, such as leveling agents, slip agents or stabilizers, etc. And additives, such as leveling agents such as Tego Rad 2100, Rad 2200N, Rad 2250, Rad2600, slip agents as Dough-Corning DC-56, 57, stabilizers as diethylethanolamine and trihexylamine and The same tertiary amine, hindered amine, organic phosphate, hindered phenol, mixtures thereof and the like can be used. The additive may comprise 0.1 to 5% by weight relative to the total weight of the composition.

The method for preparing the composition of the ultraviolet curable high reflection white ink of the present invention is as follows:

The oligomers (a), photopolymerizable monomers (b), white pigments (c), dispersants (e) and other additives (f) end-modified with an unsaturated group are added to the stirrer, and the temperature is 15 to 50 DEG C, 60% or less. After stirring at a uniform speed of 1000rpm or more using a dispersing impeller at a humidity, the stirring material is dispersed using a mill disperser. The photoinitiator (d) was added to the dispersed mill base and stirred at a uniform speed of 1000 rpm or more using a dispersion impeller at a temperature of 15 to 50 ° C. and a humidity of 60% or less. If the reaction temperature is less than 15 ° C, the viscosity of the oligomer (a) rises, a process problem occurs, and if the temperature exceeds 50 ° C, the photoinitiator (d) forms a radical to cause a curing reaction. When the reaction humidity exceeds 60%, the resulting resin composition generates bubbles during the subsequent coating process, and side reactions in which unreacted substances react with moisture in the air occur, and the stirring speed is less than 1,000 rpm. It may not be well blended.

Solvent-free UV curable white ink composition according to the present invention is excellent in physical properties such as environmental problems, processability, degree of curing, as shown in the test described below, at the same time reflectance is more than 85%, the yellowness after curing is very excellent at less than 2.00 Able to know.

The present invention also provides a reflective member and a backlight unit having the same, which are prepared by applying the above solvent-free ultraviolet curable white ink composition on top of a substrate and curing the same. The substrate is not limited to resin, glass, metal, ceramic, etc., and the reflective member may be positioned under the backlight unit to reflect light to the front surface. Examples of the backlight unit include a light source used in a display device such as an LCD, and the like, and the configuration of the backlight unit is well known in the art, and thus description thereof is omitted.

In addition, the non-solvent type UV curable white ink composition may be usefully used as a material for high illumination of reflectors and reflecting films of various structures, including lighting equipment, copying machines, display devices, and the like.

Solvent-free ultraviolet (UV) curable white ink composition of the present invention having the above configuration does not cause environmental pollution problems when applied to the optical film, processability that does not occur the problem of forming a sagging (flowing or collecting solvent) Easy to use, reflectance is more than 85%, excellent durability, fast curing speed, excellent yellowness, yellowing degree, etc., can be used for the reflective member and the backlight unit excellently.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are intended to illustrate the present invention, but the scope of the present invention is not limited thereto.

Examples 1-6 and Comparative Examples 1-4

 The composition of the ultraviolet curable high reflection white ink which concerns on this invention as shown in following [Table 1] was mix | blended.

Table 1

Oligomer Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 EB-600 30 15 18 12 7 15 21 5 EB-830 30 15 18 12 7 15 21 5 EB-1290 30 Monomer SR-502 6 6 6 6 4 3 6 6 8 2 SR-238 9 9 9 9 7 3 9 9 12 3 Pigment Ti-Pure R-902 50 50 50 44 60 75 50 50 33 80 Photoinitiator Irgacure # 184 2 2 2 2 2 2 2 2 2 2 Darocure TPO 2 2 2 2 2 2 2 2 2 Irgacure # 819 2 Dispersant DISPERBYK-111 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 additive Irganox 1076 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5

The following ingredient names and trade names are used in Table 1 and are to be understood to refer to the compounds or compositions mentioned.

Ebecryl 600 is a terminally modified epoxy acrylate oligomer commercially available from SK Cytec.

Ebecryl 830 is an unsaturated ester acrylate oligomer commercially available from SK Cytec.

Ebecryl 1290 is a urethane acrylate oligomer commercially available from SK Cytec.

SR-502 is a monomer containing an acrylate group containing an ethoxy functional group commercially available from SARTOMER.

SR-238 is a monomer containing an acrylate group containing a hexanediol functional group commercially available from SARTOMER.

Ti-Pure R-902 is a rutile titanium dioxide manufactured by Du Pont.

Irgacure # 184 is a 1-hydroxycyclohexylphenylketone sold by CIBA.

Darocure TPO is 2,4,6-trimethylbenzoyl-diphenyl-phosphineoxide sold by CIBA.

delete

Irgacure # 819 is Bis (2,4,6-trimethylbenzoyl) -phenylphosphineoxide sold by CIBA.

DISPERBYK-111 is a dispersant containing phosphoric acid and a phosphate polyester copolymer commercially available from BYK Chemie.

Irganox1076 is Octadecyl-3- (3,5-di-tert.butyl-4-hydroxyphenyl) -propionate sold by CIBA.

Evaluation method of physical property of photocurable coating resin composition

The reflectance and color of the oligomers, the amount of titanium dioxide, the type of photoinitiator of the oligomers which are end-modified with the unsaturated group of the composition of the ultraviolet curable high-reflective white ink prepared in Examples 1 to 6 and Comparative Examples 1 to 4 In order to determine the correlation, the viscosity, reflectance after curing, yellowness, leveling and curing degree of the surface after curing were measured, and the results are shown in the following [Table 2].

Viscosity

The viscosity of the composition was measured in a range of 50-90% torque at 25 ° C., using spindle 51 using a Brookfield Viscometer (Brookfield DV II +) according to ASTM D-2196.

Reflectance (% Reflectance)

Apply the composition prepared in the above example on a glass plate of 20 × 20 cm size, fix the bar coater to 1 ~ 2 mil thickness, push it into a fixed frame into which nitrogen is injected (nitrogen flow rate 40lpm), and fusion yarn (model: DRS10 / 12-QN Using a 600Watt 9mm D-bulb of)) was irradiated and cured by irradiation with a light amount of 30fpm, 1.0 J / cm ² to produce a film of about 20 ㎛ thickness. The sample film thickness which measured the film of the hardened composition from the glass plate is measured using the micrometer (MITUTOYO, 0-25 mm, 0.001 mm unit). The thickness of the film was measured by using a Minolta Spectrophotometer (Minolta Spectrophotometer, CM-3700D) and the reflectance in the visible region (400 ~ 700nm) was defined as the reflectance.

Yellow Index

Apply the composition prepared in the above example on a glass plate of 20 × 20 cm size, fix the bar coater to 1 ~ 2 mil thickness, push it into a fixed frame into which nitrogen is injected (nitrogen flow rate 40lpm), and fusion yarn (model: DRS10 / 12-QN Using a 600Watt 9mm D-bulb of the)) was irradiated and cured by irradiating a light amount of 30fpm, 1.0 J / cm 2 to produce a film having a thickness of about 20 ㎛. Measure the thickness of the sample film using a micrometer (MITUTOYO, 0 ~ 25mm, 0.001mm units) for the sample separated from the glass plate of the cured composition. The thickness of the film was measured for the yellowness (Y.I) using a Minolta Spectrophotometer (CM-3700D).

Surface leveling after curing

Apply the composition prepared in the above example on a glass plate of 20 × 20 cm size, fix the bar coater to 1 ~ 2 mil thickness, push it into a fixed frame into which nitrogen is injected (nitrogen flow rate 40lpm), and fusion yarn (model: DRS10 / 12-QN Using a 600Watt 9mm D-bulb of)) was irradiated and cured by irradiation with a light amount of 30fpm, 1.0 J / cm ² to produce a film of about 20 ㎛ thickness. The surface of the prepared specimen was measured by dividing it into the following A, B, C with the naked eye and fingers.

A: The surface of the specimen is uniformly smooth and no pigment particles are exposed on the surface

B: Specimen surface is not smooth but pigment particles are not exposed on the surface

C: surface of specimen is not smooth, pigment particles are exposed on surface

% Reacted Acrylate Unsaturation

Apply the composition prepared in the above example on a glass plate of 20 × 20 cm size, fix the bar coater to 1 ~ 2 mil thickness, push it into a fixed frame into which nitrogen is injected (nitrogen flow rate 40lpm), and fusion yarn (model: DRS10 / 12-QN Using a 600Watt 9mm D-bulb of)) was irradiated and cured by irradiation with a light amount of 30fpm, 1.0 J / cm ² to produce a film of about 20 ㎛ thickness. The degree of cure is measured using a Nicolet company (model name: protege 460, ATR mode) in which the film of the cured composition is separated from the glass plate.

[Table 2]

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Viscosity (cps) 8252 2780 3642 3217 5100 8502 4721 3711 2393 11002 Specimen Thickness (㎛) 21 20 21 21 20 20 20 21 20 21 reflectivity 86.6 86.4 86.9 85.6 87.6 88.1 86.5 86.2 83.1 88.9 Yellow road 0.45 0.22 0.65 0.21 0.10 0.20 0.31 6.23 0.43 0.22 Surface leveling after curing A A A A A B B A A C Hardness (%) 96.2 93.1 95.2 93.9 92.2 90.3 91.2 94.9 94.2 87.2

In Examples 1 to 6 and Comparative Examples 1 to 4, the content of titanium dioxide determined the reflectance, and the reflectance was 85% or more when the titanium dioxide content was 40% or more in the composition of the UV curable high-reflective white ink. Looking at Examples 1 and 2 and Comparative Example 1, the curable epoxy acrylate oligomer and unsaturated polyester oligomer are superior to the urethane acrylate oligomer. When looking at the viscosity results, although the unsaturated polyester oligomer is higher in viscosity than the urethane acrylate oligomer, when applied to the same mixture in the white ink composition, the viscosity is low, so wetting was excellent. Further, in Example 3 and Comparative Example 2, the photoinitiator 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (2,4,6-trimethylbenzoyl-diphenyl-phosphineoxide) and 1-hydroxycyclohexylphenyl ketone (1- When hydroxycyclohexylphenylketone) is used, the curing property and yellowness are excellent, and when the photoinitiator 1-hydroxycyclohexylphenylketone and bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide are used, One yellow degree fell.

Examples 4, 5, and 6 have a reflectance of 85% or more, and the leveling of the surface after curing is good and the curing property is good to moderate. In Comparative Example 3, the leveling and curing property of the surface after curing are good but the reflectance is less than 85%. It was. In Comparative Example 4, the reflectance was 85% or more, but the leveling and curing properties of the surface after curing were poor.

Claims (10)

Oligomers terminally denatured with unsaturated groups; Photopolymerizable monomers; White pigments; A solvent-free ultraviolet curing white ink composition comprising a photoinitiator; The unsaturated group-modified oligomer comprises a modified epoxy acrylate oligomer having a number average molecular weight of 500 to 1500 and an unsaturated ester acrylate oligomer having a number average molecular weight of 1000 to 3000, and within a range of 10 to 40% by weight of the total content of the composition. Solvent-free UV curable white ink composition, characterized in that it is included. According to claim 1, To improve the dispersibility of the white pigment, a dispersing agent, a leveling agent, containing a phosphoric acid polyester (phosphated polyester) copolymer and a phosphoric acid 0.01 to 20 parts by weight relative to the copolymer at room temperature, And at least one or more of the stabilizer is a non-solvent type UV curable white ink composition. The non-solvent type ultraviolet curable white ink composition according to claim 1, having a characteristic of reflectance of 85% or more when the thickness after curing is 20 µm. According to claim 1, wherein the photopolymerizable monomer is an acrylate monomer having an ethoxy functional group and an acrylate monomer having a hexanediol functional group is a solvent-free ultraviolet light, characterized in that included in the range of 10 to 30% by weight of the total content of the composition. Curable white ink composition. The non-solvent type UV curable white ink according to claim 1, wherein the white pigment is rutile titanium dioxide and has an average particle diameter in the range of 0.1 to 10 µm and is contained in the range of 40 to 75 wt% of the total content of the composition. Composition. 2. The photopolymerization initiator according to claim 1, wherein the photopolymerization initiator has an ultraviolet initiator having an absorption main peak in the ultraviolet / visible ray of 220 nm to 260 nm in methanol and an ultraviolet absorption main peak of the ultraviolet ray / visible ray in methanol of 360 nm to 400 nm. A solvent-free ultraviolet curable white ink composition comprising an initiator together. The non-solvent type UV curable white ink composition according to claim 1, wherein the photopolymerization initiator uses two types of UV initiators having a difference in absorption main peak from 100 nm to 180 nm in methanol / UV / visible light. The method of claim 6, wherein the photopolymerization initiator is 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (2,4,6-trimethylbenzoyl-diphenyl-phosphineoxide) and 1-hydroxycyclohexylphenyl ketone (1- hydroxycyclohexylphenylketone) is a solvent-free ultraviolet curing white ink composition, characterized in that included in the range of 2 to 10% by weight of the total content of the composition. A reflection member prepared by applying the non-solvent type ultraviolet curable white ink composition according to any one of claims 1 to 8 on an upper portion of a substrate and then curing. A backlight unit having the reflective member of claim 9.