WO2016047745A1

WO2016047745A1 - Coating liquid, production method for led device using same, and led device

Info

Publication number: WO2016047745A1
Application number: PCT/JP2015/077076
Authority: WO
Inventors: 禄人田口
Original assignee: コニカミノルタ株式会社
Priority date: 2014-09-26
Filing date: 2015-09-25
Publication date: 2016-03-31

Abstract

The purpose of the present invention is to provide: a coating liquid that suitably minimizes cracks during curing and that makes it possible to obtain a cured film having high reflectance and the ability to maintain said reflectance over a long period of time when, for example, a coating film formed on a substrate for an LED device is cured in order to obtain a reflective layer; and an LED device that uses the coating liquid. This coating liquid contains a white pigment, a silane compound, and a solvent. The coating liquid satisfies 0≤R2<40 (formula 1) and 0≤R4/R3≤2 (formula 2) when, within the total amount of the silane compound, the ratio of a bifunctional silane compound is denoted by R2 (mol%), the ratio of a trifunctional silane compound is denoted by R3 (mol%), and the ratio of a tetrafunctional silane compound is denoted by R4 (mol%). In addition, the volume ratio B/A of the coating liquid before and after curing thereof satisfies 0.2≤B/A≤0.7 (formula 3) when the volume of the coating liquid is denoted by A and the volume of a cured product obtained by curing the coating liquid is denoted by B.

Description

Coating liquid, LED device manufacturing method using the same, and LED device

The present invention relates to a coating solution, an LED device manufacturing method using the same, and an LED device.

In recent years, a phosphor such as a YAG phosphor has been placed in the vicinity of a gallium nitride (GaN) blue LED (Light Emitting Diode) chip, and has received blue light and blue light emitted from the blue LED chip. An LED device that obtains white light by mixing yellow light emitted from a phosphor is widely used. Also, various phosphors are arranged in the vicinity of the blue LED chip, and blue light emitted from the blue LED chip and red light and green light emitted from the phosphor upon receiving blue light are mixed to obtain white light. Equipment has also been developed.

White LED devices have a variety of uses, for example, there is a demand as an alternative to fluorescent lamps and incandescent lamps. Such an illuminating device has a configuration in which a plurality of white LED devices are combined, and how to increase the light extraction efficiency of each white LED device is important in realizing cost reduction and long life. come.

In the conventional LED device, there is a problem that the substrate on which the LED element is arranged easily absorbs the emitted light of the LED element and the fluorescence emitted from the phosphor, and the light extraction property is not sufficient. Therefore, in a general LED device, a reflector having a high light reflectance is disposed around the LED element. Such a reflector is generally formed of metal plating or the like.
However, a reflector made of metal plating cannot be formed on the entire surface of the substrate in order to prevent electrical conduction. Therefore, there is a problem that light is absorbed by the substrate in the region where the reflector is not formed.

On the other hand, a reflector in which metal plating is covered with a resin layer (Patent Document 1), and a reflector in which metal plating is covered with a white resin layer have also been proposed (Patent Document 2). In addition, a method of creating a reflective layer made of light diffusing particles and a ceramic binder on an LED substrate has been proposed (Patent Document 3).

JP 2005-136379 A JP 2011-23621 A International Publication No. 2014/017108

However, when the reflector is made of resin, or when the reflector surface made of metal plating is coated with resin as in the technique of Patent Document 1, the resin deteriorates due to heat or light, and the light reflection of the reflective layer over time. There is a problem that the property is lowered or electricity is conducted. In particular, in applications where a large amount of light is required, such as in-vehicle headlights, the resin is likely to deteriorate.

Moreover, even when it is a case where it is coated with a thermosetting resin containing a white pigment as in the technique in Patent Document 2, materials such as epoxy having an organic substance as a main skeleton are colored at a high temperature, resulting in reflection. There is a problem that the light extraction efficiency is lowered due to a decrease in the rate. Even when using a silicone resin with relatively high heat resistance, silicone has the property of being easily permeable to gas, so when it is used coated with silver or silver plating, it exists in the air. It was not possible to prevent silver from being discolored and the reflectivity from being lowered, that is, the light extraction efficiency from being lowered due to a small amount of hydrogen sulfide.

As described in Patent Document 3, if the reflector surface is covered with a reflective layer made of light diffusing particles and a ceramic binder, a decrease in reflectance due to coloring as shown in Patent Document 2 can be suppressed. . However, the coating solution of Patent Document 3 has a problem that cracks are likely to occur during curing because of a large volume change (volume shrinkage) due to curing. Further, when it is attempted to increase the thickness of the reflective layer in order to increase the reflectivity, it is necessary to increase the number of coatings, and there is a problem that the tact time increases. Furthermore, the reflective layer obtained by increasing the number of coatings tends to be difficult to obtain a sufficient reflectivity because it is not homogeneous or has a low density.

The present invention has been made in view of the above circumstances. For example, when a coating layer formed on a substrate of an LED device is cured to obtain a reflective layer, cracks at the time of curing are satisfactorily suppressed, and high reflectance is achieved. It is an object of the present invention to provide a coating liquid capable of obtaining a cured film that has a reflectance and can maintain the reflectance over a long period of time, and an LED device using the coating liquid.

[1] A coating liquid containing a white pigment, a silane compound, and a solvent, wherein the ratio of the bifunctional silane compound in the total amount of the silane compound is R2 (mol%), and the ratio of the trifunctional silane compound is R3 (mol). %) When the ratio of the tetrafunctional silane compound is R4 (mol%), both conditions of the following formula 1 and formula 2 are satisfied,
0 ≦ R2 <40 (Formula 1)
0 ≦ R4 / R3 ≦ 2 (Formula 2)
When the volume of the coating solution is A and the volume of the cured product obtained by heat-curing the coating solution at 150 ° C. for 1 hour is B, the volume ratio B / A before and after curing satisfies the condition of the following formula 3. Application liquid.
0.2 ≦ B / A ≦ 0.7 (Formula 3)
[2] The coating solution according to [1], wherein the molar ratio of the silane compound satisfies the condition of the following formula 4.
0 ≦ R4 / R3 ≦ 1.5 (Formula 4)
[3] The coating solution according to [1] or [2], wherein the volume ratio B / A before and after the curing satisfies the condition of the following formula 5.
0.25 ≦ B / A ≦ 0.6 (Formula 5)
[4] The coating liquid according to any one of [1] to [3], wherein the solvent contains at least one of a monohydric alcohol and a dihydric or higher polyhydric alcohol.
[5] The method according to any one of [1] to [4], wherein at least one selected from the group consisting of the bifunctional silane compound, the trifunctional silane compound, and the tetrafunctional silane compound is polymerized in advance. Coating liquid.
[6] The coating solution according to any one of [1] to [5], further comprising inorganic particles or clay mineral particles.
[7] The coating solution according to any one of [1] to [6], further including a silane coupling agent.
[8] The coating solution according to any one of [1] to [7], wherein the viscosity is more than 5 mPa · s and not more than 2000 mPa · s.
[9] A coating liquid containing a white pigment, a silane compound, and a solvent, wherein the ratio of the bifunctional silane compound in the total amount of the silane compound is R2 (mol%), and the ratio of the trifunctional silane compound is R3 (mol). %) When the ratio of the tetrafunctional silane compound is R4 (mol%), both conditions of the following formula 1 and formula 2 are satisfied,
0 ≦ R2 <40 (Formula 1)
0 ≦ R4 / R3 ≦ 2 (Formula 2)
A coating solution, wherein a content ratio of the solvent is in a range of 10 to 45% by mass with respect to the coating solution.
[10] A substrate, an LED element disposed on the substrate, a reflective layer disposed at least around the LED element on the substrate, and a wavelength conversion disposed on the light emitting direction of the LED element A method of manufacturing an LED device including a layer, the step of applying the coating liquid according to any one of [1] to [9] on the substrate, and curing the applied coating liquid. And a step of forming the reflective layer.
[11] The method for manufacturing an LED device according to [10], wherein the coating liquid is applied once or twice, and the applied coating liquid is cured to form the reflective layer having a thickness of 40 μm or more.
[12] A substrate, an LED element disposed on the substrate, a reflective layer disposed around the LED element on the substrate, and a wavelength conversion layer disposed on the light emitting direction of the LED element The LED device, wherein the reflective layer is a cured film of the coating liquid according to any one of [1] to [9].
[13] The LED device according to [12], wherein the wavelength conversion layer is in contact with the LED element.
[14] The LED device according to [12] or [13], wherein the reflective layer is further disposed between the substrate and the LED element.

According to the present invention, for example, when a coating layer formed on a substrate of an LED device is cured to obtain a reflective layer, cracks during curing are satisfactorily suppressed, and the reflectance is high. It is possible to provide a coating liquid capable of obtaining a cured film that can be maintained for a long period of time and an LED device using the coating liquid.

It is a schematic sectional drawing which shows an example of the LED apparatus of this invention. It is a top view which shows an example of the LED device of this invention. 2 is a graph showing an example of a solid-state Si-NMR spectrum.

1. Coating liquid The coating liquid of the present invention is a composition for forming a reflective layer of an LED device, and the coating liquid contains a white pigment, a silane compound, and a solvent. In addition to the white pigment, the coating liquid may contain inorganic particles, clay mineral particles, a silane coupling agent, and the like.

A resin is often used for the binder of the reflective layer of the conventional LED device. However, the resin may be colored or deteriorated by heat or light, and there has been a problem that the light extraction efficiency tends to decrease. Thus, it has been studied to form a reflective layer by curing a coating film of a coating solution containing a polysiloxane precursor and a white pigment. However, the volume change of the coating film when curing the coating film is large, and cracks are likely to occur due to the stress. This crack is likely to occur particularly when the thickness of the coating film is large. The reflective layer having such a crack has a low reflectivity and causes a reduction in light extraction efficiency of the LED device.

On the other hand, the coating liquid of the present invention 1) reduces the volume change due to curing, and 2) reduces the content ratio of the tetrafunctional silane compound in the polysiloxane precursor. Thereby, generation | occurrence | production of the crack at the time of hardening a coating film can be suppressed favorably. Specifically, 1) By setting the volume change due to curing to a certain value or less, the stress generated in the coating film during curing can be reduced. In order to keep the volume change due to curing below a certain level, the solvent content is preferably kept below a certain level. 2) By setting the content ratio of the tetrafunctional silane compound to a certain value or less, the hardness (or crosslinking density) of the cured product of the coating film can be prevented from becoming excessively high, and the stress generated in the coating film can be alleviated. As a result, a cured film having a high reflectance can be obtained by suppressing cracks during curing.

In addition, since the coating solution has a small solvent content, it can be formed into a thick film even with a small number of coatings. Thereby, the obtained cured film is homogeneous and dense, and can have a higher reflectance. As a result, the light extraction efficiency of the LED device can be increased.

Furthermore, since the binder of the reflective layer obtained from the coating solution is polysiloxane, the reflective layer is hardly deteriorated by light or heat. Therefore, an LED device having a reflective layer made of a cured film of the coating liquid can maintain high light extraction efficiency over a long period of time.

1-1. Alkoxysilane Compound The coating liquid of the present invention contains an alkoxysilane compound. The alkoxysilane compound is a compound that is hydrolyzed and polycondensed into a polysiloxane when the coating solution is cured. And polysiloxane becomes a binder of the above-mentioned reflective layer.

The alkoxysilane compound includes at least one of a bifunctional alkoxysilane compound, a trifunctional alkoxysilane compound, and a tetrafunctional alkoxysilane compound. The ratio of the bifunctional alkoxysilane compound to the total amount of the alkoxysilane compound is R2 (mol%), the ratio of the trifunctional alkoxysilane compound is R3 (mol%), and the ratio of the tetrafunctional alkoxysilane compound is R4 (mol%). , Both conditions of the following formula 1 and formula 2 are satisfied.
0 ≦ R2 <40 (Formula 1)
0 ≦ R4 / R3 ≦ 2 (Formula 2)
In addition, the sum total of R2, R3, and R4 is 100 mol%.

In Formula 1, when R2 is 40 or more, the polysiloxane contains a relatively large amount of organic groups derived from bifunctional alkoxysilane. As a result, it is difficult to form a sufficient siloxane bond between the reflective layer obtained by curing the coating solution and the OH group or the like on the substrate surface, and the adhesion between the reflective layer and the substrate is lowered. In addition, the gas barrier property of the reflective layer may be reduced, and the resistance to sulfurization may be reduced.

On the other hand, if the value of R4 / R3 exceeds 2 in Formula 2, that is, if the amount of the tetrafunctional alkoxysilane compound is excessive, the crosslinking density in the polysiloxane is excessively increased. For this reason, stress is not easily relieved when the alkoxysilane compound is cured, and cracks may occur. Therefore, the value of R4 / R3 is preferably 2 or less, more preferably 0 ≦ R4 / R3 ≦ 1.5, and further preferably 0 ≦ R4 / R3 <1.

The ratio of the bifunctional alkoxysilane compound, the trifunctional alkoxysilane compound, and the tetrafunctional alkoxysilane compound with respect to the total amount of the alkoxysilane compound in the coating solution is determined by the solid Si of the sample obtained by drying and solidifying the coating solution at 150 ° C. Each can be determined from the NMR spectrum.

The spectrum of solid-state Si-NMR (Nuclear Magnetic Resonance) will be described.
The tetrafunctional alkoxysilane compound polymer (polysiloxane) is represented by the SiO ₂ · nH ₂ O characteristic formula, but structurally, oxygen atoms O are bonded to the apexes of the silicon atom Si tetrahedron. These silicon atoms have a structure in which silicon atoms Si are further bonded to these oxygen atoms O and spread in a net shape.

The schematic diagrams (A) and (B) below show the Si—O net structure, ignoring the tetrahedral structure. The schematic diagram (A) shows a case where all of the oxygen atoms O are bonded to other Si atoms in the Si—O net structure. On the other hand, the schematic diagram (B) shows a case where part of the oxygen atom O is replaced with another member (here, —H) in the Si—O net structure. As shown in the schematic diagram (A), the Si atoms derived from the tetrafunctional alkoxysilane compound include four atoms (Q ⁴ ) bonded to —OSi, and three Si atoms as shown in the schematic diagram (B). Atom (Q ³ ) or the like bonded to —OSi. In the solid-state Si-NMR spectrum, these are observed as different peaks. Then, a peak based on the silicon atoms derived from the tetrafunctional alkoxysilane compound, are collectively referred to as Q sites, the peak derived from each atom, Q ⁴ peak, Q ³ peak, called .... In this specification, Q ⁰ to Q ⁴ peaks derived from the Q site are referred to as a Q ⁿ peak group. The Q ⁿ peak group of the silica film containing no organic substituent is usually observed as a multimodal peak continuous in the region of −80 to −130 ppm chemical shift.

On the other hand, a silicon atom (that is, silicon derived from a trifunctional alkoxysilane compound) in which three oxygen atoms are bonded and one non-oxygen atom (usually carbon) is bonded is generally referred to as a T site. Is done. The peak derived from the T site is observed as each peak of T ⁰ to T ³ as in the case of the Q site. In this specification, each peak derived from the T site is referred to as a ^Tn peak group. The T ⁿ peak group is generally observed as a multimodal peak continuous in a region on the higher magnetic field side (usually chemical shift of −80 to −40 ppm) than the Q ⁿ peak group.

Furthermore, a silicon atom (that is, silicon derived from a bifunctional alkoxysilane compound) in which two oxygen atoms are bonded and two atoms other than oxygen (usually carbon) are bonded is generally referred to as a D site. Is done. Similarly to the peak group derived from the Q site and the T site, the peak derived from the D site is also observed as each peak of D ⁰ to D ⁿ (D ⁿ peak group), which is further than the peak group of Q ⁿ and T ^n. It is observed as a multimodal peak in the region on the high magnetic field side (usually the region with a chemical shift of −3 to −40 ppm).

Here, when a solid Si-NMR measurement is performed, a spectrum as shown in FIG. 3 is obtained. However, FIG. 3 is an example of the spectrum of solid-state Si-NMR, and the spectrum of the cured product of the alkoxysilane compound contained in the coating solution of the present invention is not limited to this. In FIG. 3, the horizontal axis indicates the chemical shift, and the vertical axis indicates “relative strength” depending on the abundance of the compound having each structure.

In FIG. 3, D11 indicates actual measurement data. D12 indicates data modeled by a Gaussian function. D13 shows a difference spectrum. The peak P11 represents the ^{D n} peak group, the peak top of the ^{D n} peak group is present in the vicinity of chemical shift -20.0Ppm. The peak P12 represents the ^{T n} peak group, the peak top of the ^{T n} peak group is present in the vicinity of chemical shift -60.0Ppm. Further, the peak P13 represents a ^{Q n} peak group, the peak top of the ^{Q n} peak group is present in the vicinity of a chemical shift -100.0 ~ -110 ppm. That is, the spectrum of FIG. 3 shows that silicon derived from a bifunctional alkoxysilane compound, silicon derived from a trifunctional alkoxysilane compound, and silicon derived from a tetrafunctional alkoxysilane compound are included.

The area ratio of the respective peak groups of D ⁿ , T ⁿ , and Q ⁿ is equal to the molar ratio of silicon atoms placed in the environment corresponding to each peak group. Therefore, Q ⁿ peak group, T ⁿ peak group, and to the total area of the D ⁿ peak group, the ratio of the area of each peak group, the total amount of the alkoxysilane compound contained in the coating liquid (the total molar amount of silicon atoms) And the molar ratio of each alkoxysilane compound (tetrafunctional alkoxysilane compound, trifunctional alkoxysilane compound, and bifunctional alkoxysilane compound).

Here, the alkoxysilane compound may be in a monomer state; however, at least a part is preferably a polymer (oligomer) of bifunctional alkoxysilane, trifunctional alkoxysilane, or tetrafunctional alkoxysilane. If the alkoxysilane compound is an oligomer in which several to several tens of monomers are polymerized in advance, shrinkage when the coating solution is cured is reduced, and cracks are less likely to occur when the reflective layer is formed.

-Tetrafunctional alkoxysilane compound Examples of the tetrafunctional alkoxysilane compound include compounds represented by the following general formula (IV).
Si (OR ¹ ) ₄ (IV)
In the general formula (IV), each R ¹ independently represents an alkyl group or a phenyl group, preferably an alkyl group having 1 to 5 carbon atoms, or a phenyl group.

Specific examples of tetrafunctional alkoxysilane compounds include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, tetrapentyloxysilane, tetraphenyloxysilane, trimethoxymonoethoxysilane, dimethoxydiethoxysilane, and triethoxymono. Methoxysilane, trimethoxymonopropoxysilane, monomethoxytributoxysilane, monomethoxytripentyloxysilane, monomethoxytriphenyloxysilane, dimethoxydipropoxysilane, tripropoxymonomethoxysilane, trimethoxymonobutoxysilane, dimethoxydibutoxysilane , Triethoxymonopropoxysilane, diethoxydipropoxysilane, tributoxymonopropoxysilane, dimethoxymonoethoxy Nobutoxysilane, diethoxymonomethoxymonobutoxysilane, diethoxymonopropoxymonobutoxysilane, dipropoxymonomethoxymonoethoxysilane, dipropoxymonomethoxymonobutoxysilane, dipropoxymonoethoxymonobutoxysilane, dibutoxymonomethoxymonoethoxy Examples thereof include alkoxysilanes such as silane, dibutoxymonoethoxymonopropoxysilane, monomethoxymonoethoxymonopropoxymonobutoxysilane, and aryloxysilane. Among these, tetramethoxysilane and tetraethoxysilane are preferable.

Trifunctional alkoxysilane compound Examples of the trifunctional alkoxysilane compound include compounds represented by the following general formula (III).
R ² Si (OR ³ ) ₃ (III)
In the general formula (III), each R ³ independently represents an alkyl group or a phenyl group, preferably an alkyl group having 1 to 5 carbon atoms, or a phenyl group. R ² represents a hydrogen atom or an alkyl group.

Specific examples of the trifunctional alkoxysilane compound include trimethoxysilane, triethoxysilane, tripropoxysilane, tripentyloxysilane, triphenyloxysilane, dimethoxymonoethoxysilane, diethoxymonomethoxysilane, dipropoxymonomethoxysilane, Dipropoxymonoethoxysilane, dipentyloxylmonomethoxysilane, dipentyloxymonoethoxysilane, dipentyloxymonopropoxysilane, diphenyloxylmonomethoxysilane, diphenyloxymonoethoxysilane, diphenyloxymonopropoxysilane, methoxyethoxypropoxysilane, monopropoxydimethoxy Silane, monopropoxydiethoxysilane, monobutoxydimethoxysilane, monopentyloxydiethoxysila Monohydrosilane compounds such as monophenyloxydiethoxysilane; methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltripentyloxysilane, methylmonomethoxydiethoxysilane, methylmonomethoxydipropoxysilane, methylmono Monomethylsilane compounds such as methoxydipentyloxysilane, methylmonomethoxydiphenyloxysilane, methylmethoxyethoxypropoxysilane, methylmonomethoxymonoethoxymonobutoxysilane; ethyltrimethoxysilane, ethyltripropoxysilane, ethyltripentyloxysilane, ethyltri Phenyloxysilane, ethylmonomethoxydiethoxysilane, ethylmonomethoxydipropoxysilane, ethylmonomethoxydipe Monoethylsilane compounds such as tiloxysilane, ethylmonomethoxydiphenyloxysilane, ethylmonomethoxymonoethoxymonobutoxysilane; propyltrimethoxysilane, propyltriethoxysilane, propyltripentyloxysilane, propyltriphenyloxysilane, propylmono Monopropylsilane compounds such as methoxydiethoxysilane, propylmonomethoxydipropoxysilane, propylmonomethoxydipentyloxysilane, propylmonomethoxydiphenyloxysilane, propylmethoxyethoxypropoxysilane, propylmonomethoxymonoethoxymonobutoxysilane; butyltrimethoxy Silane, butyltriethoxysilane, butyltripropoxysilane, butyltripentyloxysilane, butyl Mono, such as triphenyloxysilane, butylmonomethoxydiethoxysilane, butylmonomethoxydipropoxysilane, butylmonomethoxydipentyloxysilane, butylmonomethoxydiphenyloxysilane, butylmethoxyethoxypropoxysilane, butylmonomethoxymonoethoxymonobutoxysilane A butylsilane compound is included.

When R ² represented by the general formula (III) of these trifunctional alkoxysilane compounds is a methyl group, the hydrophobicity of the resulting reflective layer surface becomes low. Thereby, when forming a wavelength conversion layer on a reflective layer, the composition for forming a wavelength conversion layer becomes easy to spread. As a result, the adhesion between the reflective layer and the wavelength conversion layer is enhanced. Examples of the trifunctional alkoxysilane compound in which R ² represented by the general formula (III) is a methyl group include methyltrimethoxysilane and methyltriethoxysilane, and is particularly preferably methyltrimethoxysilane. .

-Bifunctional alkoxysilane compound Examples of the bifunctional alkoxysilane compound include compounds represented by the following general formula (II).
R ⁴ ₂ Si (OR ⁵ ) ₂ (II)
In the general formula (II), each R ⁵ independently represents an alkyl group or a phenyl group, preferably an alkyl group having 1 to 5 carbon atoms, or a phenyl group. R ⁴ represents a hydrogen atom or an alkyl group.

Specific examples of the bifunctional alkoxysilane compound include dimethoxysilane, diethoxysilane, dipropoxysilane, dipentyloxysilane, diphenyloxysilane, methoxyethoxysilane, methoxypropoxysilane, methoxypentyloxysilane, methoxyphenyloxysilane, ethoxy Propoxysilane, ethoxypentyloxysilane, ethoxyphenyloxysilane, methyldimethoxysilane, methylmethoxyethoxysilane, methyldiethoxysilane, methylmethoxypropoxysilane, methylmethoxypentyloxysilane, methylmethoxyphenyloxysilane, ethyldipropoxysilane, ethyl Methoxypropoxysilane, ethyldipentyloxysilane, ethyldiphenyloxysilane, propyldimethoxysilane , Propylmethoxyethoxysilane, propylethoxypropoxysilane, propyldiethoxysilane, propyldipentyloxysilane, propyldiphenyloxysilane, butyldimethoxysilane, butylmethoxyethoxysilane, butyldiethoxysilane, butylethoxypropoxysilane, butyldipropoxy Silane, butylmethyldipentyloxysilane, butylmethyldiphenyloxysilane, dimethyldimethoxysilane, dimethylmethoxyethoxysilane, dimethyldiethoxysilane, dimethyldipentyloxysilane, dimethyldiphenyloxysilane, dimethylethoxypropoxysilane, dimethyldipropoxysilane, diethyldimethoxy Silane, diethylmethoxypropoxysilane, diethyldiethoxysilane Diethylethoxypropoxysilane, dipropyldimethoxysilane, dipropyldiethoxysilane, dipropyldipentyloxysilane, dipropyldiphenyloxysilane, dibutyldimethoxysilane, dibutyldiethoxysilane, dibutyldipropoxysilane, dibutylmethoxypentyloxysilane, dibutylmethoxy Phenyloxysilane, methylethyldimethoxysilane, methylethyldiethoxysilane, methylethyldipropoxysilane, methylethyldipentyloxysilane, methylethyldiphenyloxysilane, methylpropyldimethoxysilane, methylpropyldiethoxysilane, methylbutyldimethoxysilane, methyl Butyldiethoxysilane, methylbutyldipropoxysilane, methylethylethoxypropoxy Run, ethylpropyldimethoxysilane, ethylpropylmethoxyethoxysilane, dipropyldimethoxysilane, dipropylmethoxyethoxysilane, propylbutyldimethoxysilane, propylbutyldiethoxysilane, dibutylmethoxyethoxysilane, dibutylmethoxypropoxysilane, dibutylethoxypropoxysilane, etc. Is included. Of these, dimethoxysilane, diethoxysilane, methyldimethoxysilane, and methyldiethoxysilane are preferable.

-Oligomer An oligomer that can be an alkoxysilane compound is prepared by mixing a bifunctional alkoxysilane compound, a trifunctional alkoxysilane compound, and a tetrafunctional alkoxysilane compound in a desired ratio and reacting them in the presence of an acid catalyst, water, and a solvent. can get. The molecular weight of the oligomer is adjusted by the reaction time, temperature, water concentration, and the like.

The oligomer preferably has a weight average molecular weight of 500 to 20000 as measured by GPC (gel permeation chromatograph), more preferably 1000 to 10,000, and even more preferably 1500 to 6000. If the degree of polymerization of the oligomer is too high, the viscosity of the coating solution may become excessively high, or the alkoxysilane compound may precipitate in the coating solution.

Examples of solvents for preparing oligomers include monohydric alcohols such as methanol, ethanol, propanol and n-butanol; alkyl carboxylic acid esters such as methyl-3-methoxypropionate and ethyl-3-ethoxypropionate; ethylene Polyhydric alcohols such as glycol, diethylene glycol, propylene glycol, glycerin, trimethylolpropane, hexanetriol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl Ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, pro Monoethers of polyhydric alcohols such as lenglycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, or their monoacetates; esters such as methyl acetate, ethyl acetate, butyl acetate Ketones such as acetone, methyl ethyl ketone, methyl isoamyl ketone; ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dipropyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol Methyl Polyhydric alcohols ethers and polyvalent all alkyl etherifying hydroxyl groups of alcohols such Chirueteru; and the like. These may be added alone or in combination of two or more.

-Content of alkoxysilane compound The total amount of alkoxysilane compound contained in the coating solution is preferably 3 to 40% by mass with respect to the total mass of components other than the solvent (including water) contained in the coating solution. More preferably, it is 5 to 30% by mass. When the total amount of the alkoxysilane compound is less than 3% by mass, the white pigment is not sufficiently bound in the resulting reflective layer. As a result, pigment powder is easily generated on the surface of the reflective layer. On the other hand, when the total amount of the alkoxysilane compound exceeds 40% by mass, the amount of the white pigment is relatively reduced, and the light reflectivity of the reflective layer tends to be low.

1-2. Solvent The solvent contained in the coating solution includes water or an organic solvent. The organic solvent may be any organic solvent that is compatible with the aforementioned alkoxysilane compound and can uniformly disperse the white pigment or the like. Examples of such organic solvents include monohydric alcohols, dihydric or higher polyhydric alcohols, ester solvents and the like.

Examples of monohydric alcohols include methanol, ethanol, propanol, butanol and the like. The polyhydric alcohol may be either a diol or a triol. Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, diethylene glycol, glycerin, 1,3-butanediol, 1,4-butanediol, and preferably ethylene glycol, propylene glycol, 1,3-butane. Diol, 1,4-butanediol and the like are included. Examples of the ester solvent include methyl-3-methoxypropionate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate and the like.

Among these, the organic solvent preferably contains at least one of a monohydric alcohol and a polyhydric alcohol.

The solvent can further include water. When water is contained in the coating solution, water enters between the layers of the clay mineral particles, the clay mineral particles swell, and the viscosity of the coating solution is more likely to increase. The water content is preferably 0 to 30% by mass, more preferably 0 to 20% by mass, based on the entire solvent.

The total amount of the solvent contained in the coating solution is preferably 10 to 45% by mass and more preferably 20 to 40% by mass with respect to the total amount of the coating solution from the viewpoint of setting the volume ratio before and after curing in the above range. preferable. If the total amount of the solvent is excessively small, the fluidity of the coating solution becomes too low and the coating stability tends to be lowered. On the other hand, if the total amount of the solvent is excessively large, the volume change before and after curing becomes too large.

1-3. White pigment The white pigment contained in the coating liquid plays a role of reflecting light emitted from the LED element in the reflective layer. In the present invention, the white pigment is a particle having an average primary particle size of more than 100 nm and 20 μm or less, and a refractive index of light having a wavelength of 587.6 nm of 1.6 or more. The average primary particle size of the white pigment is preferably larger than 100 nm and not larger than 10 μm, more preferably 200 nm to 2.5 μm. The “average primary particle size” refers to the value of D50 measured with a laser diffraction particle size distribution meter. Examples of the laser diffraction particle size distribution measuring device include a laser diffraction particle size distribution measuring device manufactured by Shimadzu Corporation.

Examples of white pigments include barium carbonate, barium sulfate, zinc oxide, magnesium oxide, calcium oxide, titanium oxide, aluminum oxide, zirconium oxide, zinc sulfide, barium sulfate, yttrium oxide, aluminum hydroxide, boron nitride, aluminum nitride, Examples include potassium titanate, barium titanate, aluminum titanate, strontium titanate, calcium titanate, magnesium titanate, and hydroxyapatite. Among these, titanium oxide, aluminum oxide, barium sulfate, zinc oxide, yttrium oxide, boron nitride, and aluminum nitride are particularly preferable.

When boron nitride is contained in the white pigment, the resulting reflective layer has high thermal conductivity. As a result, the heat generated from the LED element can be quickly released from the substrate. Therefore, the temperature of the LED device can be kept low, and the device life can be extended.

The amount of the white pigment contained in the coating solution is preferably 50 to 98% by mass, more preferably 60 to 98% by mass, and still more preferably based on the mass of the solid content after heat curing of the coating solution. Is 70 to 95% by mass. When the amount of the white pigment is 50% by mass or more, the light reflectivity of the resulting reflective layer is likely to be sufficiently increased. On the other hand, when the content of the white pigment is 95% by mass or less, the amount of the binder is relatively increased and the white pigment is easily bound. The mass of the solid content after heat curing of the coating solution is the mass of a cured product obtained by curing the coating solution at 150 ° C. for 1 hour. On the other hand, the amount of the white pigment can be specified by analyzing the blending amount at the time of preparing the coating solution and the following procedures 1) to 3). That is, 1) SEM-EDX analysis is performed on the cured product obtained by curing the coating solution at 150 ° C. for 1 hour, and the contrast of the SEM photograph and the ratio of each element in the area are obtained. 2) The cured product of the coating solution is structurally analyzed by XRD to identify the type of white pigment. 3) The content ratio of the white pigment specified in 2) above in the cured product is determined from the elemental ratio determined in 1) above.

1-4. Inorganic particles The coating solution may further contain inorganic particles. The inorganic particles are particles made of an inorganic material other than the white pigment described above. The inorganic particles can be, for example, metal oxide fine particles having an average particle size of 5 nm or more and less than 100 nm. When the metal oxide fine particles are contained in the coating solution, fine irregularities are generated on the surface of the resulting reflective layer, and an anchor effect is easily exhibited between the reflective layer and other layers. Moreover, when metal oxide fine particles are contained in the coating solution, the stress generated in the film during the polycondensation of the alkoxysilane compound is relaxed, and cracks are less likely to occur in the resulting reflective layer.

The type of metal oxide fine particles is not particularly limited, but is relatively easy to obtain from the group of aluminum oxide, zirconium oxide, zinc oxide, tin oxide, yttrium oxide, cerium oxide, titanium oxide, copper oxide, and bismuth oxide. One or more selected metal oxide fine particles are preferable.

The surface of the metal oxide fine particles may be treated with a silane coupling agent or a titanium coupling agent. By the surface treatment, the compatibility between the metal oxide fine particles and the alkoxysilane compound or the organic solvent is increased.

The average particle diameter of the metal oxide fine particles is preferably 5 to 100 nm, more preferably 5 to 80 nm, still more preferably 5 to 50 nm in consideration of the respective effects described above. By setting the average particle diameter in such a range, fine irregularities can be formed on the surface of the reflective layer, and the anchor effect described above can be obtained. The average particle diameter of the metal oxide fine particles is measured, for example, by a Coulter counter method.

The metal oxide fine particles may be porous, and the specific surface area is preferably 200 m ² / g or more. If the metal oxide fine particles are porous, impurities are easily adsorbed in the porous voids.

The amount of the metal oxide fine particles contained in the coating solution is preferably 0.1 to 20% by mass with respect to the total mass (total amount of solid content) of components other than the solvent contained in the coating solution. More preferably, it is ˜10% by mass. If the amount of the metal oxide fine particles is too small, the above-described anchor effect is not sufficient. On the other hand, if the amount is too large, the amount of the alkoxysilane compound is relatively reduced, and the strength of the resulting reflective layer may be reduced.

Meanwhile, the inorganic particles may include other inorganic particles having an average primary particle size of 100 nm or more and 100 μm or less. When such other inorganic particles are contained, the gaps between the white pigments are filled with the inorganic particles, and the viscosity of the coating liquid tends to increase. Further, since the binder in the gaps between the particles such as white pigment particles and inorganic particles is filled with the inorganic fine particles, the crack resistance during curing can be improved.

Examples of other inorganic particles include oxide particles such as silicon oxide, fluoride particles such as magnesium fluoride, and mixtures thereof. The other inorganic particles are preferably oxide particles, and particularly preferably silicon oxide. The surface of other inorganic particles may be treated with a silane coupling agent or a titanium coupling agent. By the surface treatment, compatibility between the other inorganic particles and the alkoxysilane compound or the organic solvent is increased.

The content of other inorganic particles contained in the coating solution is preferably 0.1 to 10% by mass, more preferably 0.2 to 7% by mass, based on the total mass of the coating solution. . This is because if the other inorganic particles exceed 10% by mass, cracks are likely to occur during the formation of the reflective layer, and if it is less than 0.1%, the thickening effect of the coating solution is reduced.

The average particle diameter of the other inorganic particles is preferably 100 nm or more and 50 μm or less, and more preferably 1 μm or more and 30 μm or less from the viewpoint of filling a gap generated at the interface between the white pigments. The average particle diameter of other inorganic particles can be measured by, for example, a Coulter counter method.

1-5. Clay mineral particles The coating liquid may contain clay mineral particles. When clay mineral particles are contained in the coating solution, the viscosity of the coating solution increases, and sedimentation of the white pigment is suppressed. Examples of clay mineral particles include layered silicate minerals, imogolite, allophane and the like. These particles have a very large surface area and can increase the viscosity of the coating solution in a small amount.

Here, the layered silicate mineral is preferably a clay mineral having a mica structure, a kaolinite structure, or a smectite structure. The layered silicate mineral particles tend to form a card house structure when the coating solution is left standing. When the layered silicate mineral particles form a card house structure, the viscosity of the coating solution is greatly increased. On the other hand, the card house structure is apt to collapse by applying a certain pressure, thereby reducing the viscosity of the coating solution. That is, when the layered silicate mineral particles are contained in the coating solution, the viscosity of the coating solution increases in a stationary state, and the viscosity of the coating solution decreases when a certain pressure is applied.

Examples of such layered silicate minerals include natural or synthetic hectrite, saponite, stevensite, hydelite, montmorillonite, nontrinite, bentonite, laponite and other smectite clay minerals, and Na-type tetralithic fluoric mica. Non-swelling mica such as swellable mica genus clay minerals such as Li-type tetralithic fluorine mica, Na-type fluorine teniolite, Li-type fluorine teniolite, muscovite, phlogopite, fluorine phlogopite, sericite, potassium tetrasilicon mica Genus clay minerals, vermiculite and kaolinite, or mixtures thereof.

Examples of commercial products of clay mineral particles include Laponite XLG (synthetic hectorite analogue manufactured by LaPorte, UK), Laponite RD (Synthetic hectorite analogue produced by LaPorte, UK), Thermabis (Synthetic product, Henkel, Germany) Hectorite-like substance), smecton SA-1 (saponite-like substance manufactured by Kunimine Industry Co., Ltd.), Bengel (natural bentonite sold by Hojun Co., Ltd.), Kunivia F (natural montmorillonite sold by Kunimine Industry Co., Ltd.), bee gum ( Natural hectorite manufactured by Vanderbilt, USA, Daimonite (synthetic swellable mica manufactured by Topy Industries, Ltd.), Micromica (synthetic non-swellable mica, manufactured by Coop Chemical Co., Ltd.), Somasifu (Coop Chemical Co., Ltd.) ) Synthetic swelling mica), SWN (Synthetic smectite manufactured by Coop Chemical Co., Ltd.), SWF Synthetic smectite manufactured by Co-op Chemical Co., Ltd., M-XF (white mica manufactured by Repco Co., Ltd.), S-XF (metal mica manufactured by Repco Co., Ltd.), PDM-800 (manufactured by Topy Industries, Ltd.) Fluorine phlogopite mica), sericite OC-100R (sericite produced by Oakem Tsusho Co., Ltd.), PDM-K (G) 325 (potassium tetrasilicon mica produced by Topy Industries, Ltd.), and the like.

The content of clay mineral particles is preferably from 0.1 to 5% by mass, more preferably from 0.1 to 3% by mass, based on the total mass of the coating solution. When the content of clay mineral particles is small, the viscosity of the coating solution is difficult to increase, and the white pigment tends to settle. On the other hand, if the content of the clay mineral particles is excessive, the viscosity of the coating solution becomes too high, and the coating solution may not be discharged uniformly from the coating device.

The surface of the clay mineral particles may be modified (surface treatment) with an ammonium salt or the like in consideration of compatibility with the solvent in the coating solution.

The total content of the inorganic particles and the clay mineral particles is preferably 2% by mass or less based on the total mass of the coating liquid (or the solid content of the coating liquid) from the viewpoint of improving the coating stability of the coating liquid. It is more preferable that it is 1.8 mass% or less.

1-6. Silane coupling agent The coating solution may further contain a silane coupling agent. When the silane coupling agent is contained in the coating solution, the adhesion between the resulting reflective layer and the substrate is increased, and the durability of the LED device is improved.

Examples of silane coupling agents include vinyltrimethoxysilane, vinyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyl Methyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3 -Acryloxypropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-A Nopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl-butylidene) propylamine, N-phenyl-3-aminopropyltriethoxysilane, N- (vinyl) Benzyl) -2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, 3-ureidopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 3-mercaptopropylmethyldimethoxysilane, 3-mercaptopropyltrimethoxysilane Bis (triethoxysilylpropyl) tetrasulfide, 3-isocyanatopropyltriethoxysilane and the like. These coating solutions may contain only one kind or two or more kinds.

The amount of the silane coupling agent contained in the coating solution is preferably 0.5 to 10% by mass relative to the total mass of components other than the solvent (including water) contained in the coating solution. % Is more preferable. If the amount of the silane coupling agent is too small, the adhesion between the resulting reflective layer and the substrate is not sufficiently increased, and if it is too large, the heat resistance may be lowered.

1-7. Metal alkoxide or metal chelate The coating solution may contain a metal alkoxide or metal chelate containing a metal element other than Si element. The metal alkoxide or metal chelate forms a metalloxane bond with the aforementioned alkoxysilane compound or a hydroxyl group present on the substrate surface during the formation of the reflective layer. Since the metalloxane bond is very strong, when the coating liquid contains a metal alkoxide or a metal chelate, the adhesion between the resulting reflective layer and the substrate increases.

Further, a part of the metal alkoxide or metal chelate forms a nano-sized cluster composed of a metalloxane bond in the cured film (reflective layer) of the coating solution. Due to the photocatalytic effect of this cluster, it is possible to oxidize a highly corrosive sulfide gas or the like existing in the vicinity of the LED device and change it to a sulfur dioxide gas or the like having a low corrosivity.

The metal element contained in the metal alkoxide or metal chelate is preferably a group 4 or group 13 metal element other than Si, and a compound represented by the following general formula (V) is preferable.
M ^{m +} X _n Y _mn (V)
In the general formula (V), M represents a group 4 or group 13 metal element (excluding Si), and m represents the valence of M (3 or 4). X represents a hydrolyzable group, and n represents the number of X groups (an integer of 2 or more and 4 or less). However, m ≧ n. Y represents a monovalent organic group.

In the general formula (V), the group 4 or group 13 metal element represented by M is preferably aluminum, zirconium, or titanium, and particularly preferably zirconium. A cured product of zirconium alkoxide or chelate does not have an absorption wavelength in the emission wavelength region of a general LED element (particularly blue light (wavelength 420 to 485 nm). That is, the cured product contains light from the LED element. Is difficult to absorb.

In the general formula (V), the hydrolyzable group represented by X may be a group that is hydrolyzed with water to form a hydroxyl group. Preferable examples of the hydrolyzable group include a lower alkoxy group having 1 to 5 carbon atoms, an acetoxy group, a butanoxime group, a chloro group and the like. In general formula (V), all the groups represented by X may be the same group or different groups.

The hydrolyzable group represented by X is hydrolyzed and released during the formation of the reflective layer. Therefore, the compound produced after hydrolysis from the group represented by X is preferably neutral and light boiling. Therefore, the group represented by X is preferably a lower alkoxy group having 1 to 5 carbon atoms, more preferably a methoxy group or an ethoxy group.

In the general formula (V), the monovalent organic group represented by Y may be a monovalent organic group contained in a general silane coupling agent. Specifically, the aliphatic group, alicyclic group, aromatic group, fatty acid having 1 to 1000 carbon atoms, preferably 500 or less, more preferably 100 or less, further preferably 40 or less, and particularly preferably 6 or less. It may be a ring aromatic group. The organic group represented by Y may be an aliphatic group, an alicyclic group, an aromatic group, or a group in which an alicyclic aromatic group is bonded via a linking group. The linking group may be an atom such as O, N, or S, or an atomic group containing these.

The organic group represented by Y may have a substituent. Examples of the substituent include halogen atoms such as F, Cl, Br, and I; vinyl group, methacryloxy group, acryloxy group, styryl group, mercapto group, epoxy group, epoxycyclohexyl group, glycidoxy group, amino group, cyano group, Organic groups such as nitro group, sulfonic acid group, carboxy group, hydroxy group, acyl group, alkoxy group, imino group and phenyl group are included.

Specific examples of the metal alkoxide or metal chelate represented by the general formula (V) include aluminum triisopropoxide, aluminum tri-n-butoxide, aluminum tri-t-butoxide, aluminum triethoxide and the like.

Specific examples of the metal alkoxide or metal chelate of zirconium represented by the general formula (V) include zirconium tetramethoxide, zirconium tetraethoxide, zirconium tetra n-propoxide, zirconium tetra i-propoxide, zirconium tetra n- Examples include butoxide, zirconium tetra-i-butoxide, zirconium tetra-t-butoxide, zirconium dimethacrylate dibutoxide, dibutoxyzirconium bis (ethylacetoacetate) and the like.

Specific examples of the metal alkoxide or metal chelate of the titanium element represented by the general formula (V) include titanium tetraisopropoxide, titanium tetra n-butoxide, titanium tetra i-butoxide, titanium methacrylate triisopropoxide, titanium tetra Examples include methoxypropoxide, titanium tetra n-propoxide, titanium tetraethoxide, titanium lactate, titanium bis (ethylhexoxy) bis (2-ethyl-3-hydroxyhexoxide), titanium acetylacetonate and the like.

However, the metal alkoxides or metal chelates exemplified above are a part of commercially available organometallic alkoxides or metal chelates. Metal alkoxides or metal chelates shown in the list of coupling agents and related products in Chapter 9 “Optimum Utilization Technology of Coupling Agents” published by the National Institute of Science and Technology are also applicable to the present invention.

The amount of the metal alkoxide or metal chelate contained in the coating solution is preferably 1 to 10% by mass relative to the total mass of components other than the solvent (including water) contained in the coating solution, and 2 to 7 parts by mass It is more preferable that If the content is too small, the effect of improving the adhesion cannot be obtained, and if the content is too large, the storage stability of the coating solution decreases.

1-8. Other components The coating solution may contain components other than the white pigment, alkoxysilane compound, organic solvent, inorganic particles, clay mineral particles, silane coupling agent, metal alkoxide, or metal chelate as necessary. Good.

1-9. Preparation method of coating solution The preparation method of the coating solution may be a method of mixing raw materials such as white pigments, alkoxysilane compounds, organic solvents, inorganic particles, clay mineral particles, silane coupling agents, A method of mixing a plurality of raw materials in advance and mixing the mixed liquids later may be used. In order to enhance the thickening effect of inorganic particles and clay mineral particles, it is preferable to disperse one or both of inorganic particles and clay mineral particles in a solvent and then mix with the remaining components. The following method is mentioned as an example of the preparation method of a coating liquid.

A composition containing an alkoxysilane compound (oligomer) by mixing a bifunctional alkoxysilane compound, a trifunctional alkoxysilane compound, and a tetrafunctional alkoxysilane compound in an arbitrary ratio and polymerizing them in the presence of water, an organic solvent, and a catalyst. To prepare. On the other hand, a composition containing an organic solvent, inorganic particles, clay mineral particles, silane coupling agent and the like is prepared. And the composition containing an alkoxysilane compound, the composition containing an inorganic particle etc., and a white pigment are fully mixed, and a coating liquid is obtained.

Here, in order to improve the uniformity in the coating liquid, it is preferable to disperse all or part of the raw material of the coating liquid with the following apparatus. Moreover, in order to improve the dispersibility of a white pigment, it is preferable to disperse | distribute a white pigment at least once with the following apparatuses. When the white pigment is dispersed with the following apparatus, aggregation of the white pigment is reduced, and a denser and highly reflective coating film is obtained.

・ Mixing / dispersing device Mixing / dispersing of the mixed solution is, for example, a magnetic stirrer, an ultrasonic dispersing device, a homogenizer, a stirring mill, a blade kneading stirring device, a thin-film swirling type dispersing device, a high-pressure impact dispersing device, a rotation and revolution mixer, etc. Can be done.

All known devices can be used as the stirring device used for stirring the mixed solution. For example, Ultra Turrax (manufactured by IKA Japan), TK homomixer (manufactured by Primix), TK pipeline homomixer (manufactured by Primics), TK Philmix (manufactured by Primix), Claremix (manufactured by M Technique), Medialess stirrers such as Claire SS5 (made by M Technique), Cavitron (made by Eurotech), Fine Flow Mill (made by Taiheiyo Kiko), vacuum emulsifier stirrer (made by Nippon Seiki Seisakusho), Viscomill (made by IMEX) ), Apex Mill (manufactured by Kotobuki Kogyo Co., Ltd.), Star Mill (manufactured by Ashizawa, Finetech Co., Ltd.), DMPA / S Super Flow (manufactured by Eirich Japan), MP Mill (manufactured by Inoue Seisakusho), spike mill (manufactured by Inoue Seisakusho) Mighty mill (Inoue Seisakusho Co., Ltd.), SC mill (Mitsui Mining Co., Ltd.) Media agitator like and a pressure type homogenizer (such as manufactured by SMT Co., Ltd.), Ultimizer (Sugino Machine Ltd.), Nanomizer (manufactured by Yoshida Kikai), and a high-pressure impact type dispersing device such as NANO 3000 (manufactured by Bitsubusha). In addition, a rotating / revolving mixer such as Awatori Nertaro (manufactured by Shinky Corp.) or an ultrasonic dispersing device can be suitably used.

1-10. Physical Properties of Coating Solution Viscosity of Coating Solution The viscosity of the coating solution measured at 25 ° C. with a vibration viscometer is preferably more than 5 mPa · s and not more than 2000 mPa · s. As an example of the vibration type viscometer, VISCOMATE MODEL VM-10A (manufactured by Seconic Corporation) can be mentioned. The above value is a value one minute after the vibrator is immersed in the liquid. If the viscosity of the coating solution exceeds 5 mPa · s, the white pigment is difficult to settle. On the other hand, if it is 2000 mPa · s or less, the coating stability from various coating devices tends to increase.

-Volume ratio of coating liquid In this invention, it is preferable that the volume change before and behind hardening of a coating liquid is small from a viewpoint of preventing the crack at the time of making it harden | cure after apply | coating a coating liquid. When the volume of the coating solution before curing is A and the volume of the cured product obtained by curing the coating solution at 150 ° C. for 1 hour is B, the volume ratio B / A before and after curing satisfies the condition of the following formula 3. It is preferable.
0.2 ≦ B / A ≦ 0.7 (Formula 3)

If B / A is less than 0.2, the volume change due to curing is large, so that a large stress is likely to occur. For this reason, cracks at the time of curing tend to occur, particularly when a thick film is applied and formed. When B / A is more than 0.7, the fluidity of the coating liquid is lowered, and the stability of the ejection amount during film formation tends to be lowered. A more preferable range of B / A is 0.25 ≦ B / A ≦ 0.6, and further preferably 0.30 ≦ B / A ≦ 0.6.

The volume ratio B / A before and after curing can be measured by the following procedure.
1) The volume of the coating solution is measured with a graduated cylinder in an atmosphere of 25 ° C., and is defined as volume A before curing.
2) After coating the coating solution on a Teflon (registered trademark) substrate, the coating film is heated and cured at 150 ° C. for 1 hour, and then peeled from the Teflon (registered trademark) substrate to obtain a cured product. The weight of the obtained cured product is measured in an atmosphere at 25 ° C. Furthermore, the specific gravity of the obtained cured product is measured in an atmosphere of 25 ° C. by Archimedes method. Then, the volume B of the cured product is calculated from the weight of the cured product and the specific gravity measured by the Archimedes method.
3) The volume ratio B / A is calculated from the volume A measured in 1) and the volume B calculated in 2).

The volume ratio before and after curing can be adjusted mainly by the solvent content ratio of the coating solution. In order to make the volume change before and after curing within the above range, it is preferable to reduce the solvent content ratio in the coating solution; specifically, it is preferably 10% by mass or more and 45% by mass or less.

2. LED Device FIG. 1 shows a schematic cross-sectional view of an LED device 100 having a reflective layer made of a cured film of the aforementioned coating solution, and FIG. FIG. 1 corresponds to a cross-sectional view taken along line AA in FIG. As described above, the LED device 100 includes the substrate 1, the LED element 2 disposed on the substrate 1, and the reflective layer 21 disposed at least around the LED element 2 on the substrate 1. Moreover, it further has the wavelength conversion layer 11 arrange | positioned on the light emission direction of an LED element as needed.

The LED device 100 of the present invention has a reflective layer 21 that reflects the emitted light of the LED element 2 and the like to the light extraction surface 10A side. Therefore, the light extraction efficiency from the LED device 100 of the present invention is very high. Further, since the binder of the reflective layer 21 is polysiloxane, it is resistant to light and heat, and the reflective layer 21 is unlikely to deteriorate. Therefore, according to the LED device 100 of the present invention, high light extraction efficiency is maintained over a long period of time.

2-1. Substrate The substrate 1 preferably has insulating properties and heat resistance, and is preferably made of a ceramic resin or a heat resistant resin. Examples of the heat resistant resin include liquid crystal polymer, polyphenylene sulfide, aromatic nylon, epoxy resin, hard silicone resin, polyphthalic acid amide and the like.

The substrate 1 may contain an inorganic filler. The inorganic filler can be titanium oxide, zinc oxide, alumina, silica, barium titanate, calcium phosphate, calcium carbonate, white carbon, talc, magnesium carbonate, boron nitride, glass fiber, and the like.

The substrate 1 may have a cavity as shown in FIG. 1, but may have a flat plate shape.

In addition, an electrode 3 made of metal is formed on the substrate 1, and the electrode 3 has a function of supplying electricity to the LED element 2 from a power source (not shown) arranged outside the substrate 1. . The shape of the electrode 3 is not particularly limited, and is appropriately selected according to the type and application of the light emitting device 100. The method for producing the substrate 1 having the electrodes 3 is not particularly limited, and is generally obtained by integrally molding a lead frame having a desired shape and a resin.

2-2. LED element The LED element 2 is an element that is electrically connected to the electrode 3 formed on the substrate 1 and emits light of a specific wavelength. In the LED device 100 shown in FIG. 1, the LED element 2 is disposed on the bottom surface 1 a of the truncated cone-shaped cavity (concave portion) of the substrate 1.

The wavelength of light emitted from the LED element 2 is not particularly limited. The LED element 2 may be, for example, an element that emits blue light (light of about 420 nm to 485 nm) or an element that emits ultraviolet light. Furthermore, an element that emits green light, red light, or the like may be used.

The configuration of the LED element 2 is not particularly limited. When the LED element 2 is an element that emits blue light, the LED element 2 includes an n-GaN compound semiconductor layer (cladding layer), an InGaN compound semiconductor layer (light emitting layer), and a p-GaN compound semiconductor layer. It may be a laminate of (clad layer) and a transparent electrode layer.

Further, the shape of the LED element 2 is not particularly limited, and may have, for example, a light emitting surface of 200 to 300 μm × 200 to 300 μm. The height of the LED element 2 is usually about 50 to 200 μm. The LED element 2 may be one in which light is extracted not only from the top surface but also from the side surface and the bottom surface. In the LED device 100 shown in FIG. 1, only one LED element 2 is disposed on the substrate 1, but a plurality of LED elements 2 may be disposed on the substrate 1.

The connection method between the LED element 2 and the electrode 3 is not particularly limited. For example, the LED element 2 and the electrode 3 may be connected via a metal wire 4 as shown in FIG. Moreover, the LED element 2 and the electrode 3 may be connected via a protruding electrode (not shown). A mode in which the LED element 2 and the electrode 3 are connected via the metal wire 4 is referred to as a wire bonding type. On the other hand, a mode in which the LED element 2 and the electrode 3 are connected via a protruding electrode is called a flip chip bonding type.

2-3. Reflective Layer The reflective layer 21 is a layer that reflects the emitted light from the LED element 2 and the fluorescence emitted by the phosphor contained in the wavelength conversion layer 11 to the light extraction surface 10 </ b> A side of the LED device 100. By providing the reflective layer 21, the amount of light extracted from the light extraction surface 10A of the LED device 100 increases. The reflective layer 21 is obtained by applying and curing the above-described coating solution.

In the LED device 100 shown in FIG. 1, the reflective layer 21 is disposed on the substrate 1 excluding the region where the LED elements 2 are disposed. The reflective layer 21 is arranged in a mortar shape continuously from the bottom surface 1 a to the side surface 1 b of the truncated cone-shaped cavity (concave portion) of the substrate 1. The reflection layer 21 is formed in a ring shape concentric with the wavelength conversion layer 11 on the outer periphery of the wavelength conversion layer 11 in a top view.

The reflective layer 21 is formed on the surface of the substrate 1 at least outside the region where the LED elements 2 are arranged. The arrangement region of the LED element 2 refers to a light emitting surface of the LED element 2 and a connection portion between the LED element 2 and the electrode 3. That is, the reflective layer 21 is formed in a region that does not hinder the emission of light from the LED element 2 and the connection between the LED element 2 and the electrode 3.

As shown in FIGS. 1 and 2, when the substrate 1 has a cavity, it is preferable that the reflective layer 21 is also formed on the inner wall surface 1b of the cavity. This is because when the reflective layer 21 is formed on the cavity inner wall surface 1b, the light traveling in the horizontal direction on the surface of the wavelength conversion layer 11 can be reflected by the reflective layer 21 and extracted.

In the flip chip bonding type light emitting device 100, the reflective layer 21 may be formed in the gap between the LED element 2 and the substrate 1.

The thickness of the reflective layer 21 may be 5 μm or more, preferably 20 μm or more, more preferably 40 μm or more, and particularly preferably 60 μm or more. If the thickness of the reflective layer 21 is less than 5 μm, the light reflectivity of the reflective layer 21 may not be sufficient, and the light extraction efficiency may not be sufficient. The thickness of the reflective layer 21 may be 300 μm or less, preferably 250 μm or less, more preferably 200 μm or less. If the thickness of the reflective layer 21 exceeds 300 μm, cracks may easily occur in the reflective layer 21.

The thickness of the reflective layer 21 means the maximum thickness of the reflective layer 21 formed on the light emitting surface of the LED element 2. The thickness of the reflective layer 21 can be measured with a laser holo gauge.

The reflective layer 21 may be a cured product of a coating film of the coating liquid of the present invention. Since the coating liquid of the present invention has a small volume change due to curing and a small content of the tetrafunctional silane compound, the occurrence of cracks during curing can be satisfactorily suppressed. Moreover, since the coating liquid of this invention has few solvent content ratios, the hardened | cured material obtained can have a homogeneous and high density. As a result, the reflective layer 21 can have a high reflectance.

2-4. Wavelength Conversion Layer The wavelength conversion layer 11 includes phosphor particles and a binder. The phosphor particles receive light (excitation light) emitted from the LED element 2 and emit fluorescence. By mixing the excitation light and the fluorescence, the color of the light from the LED device 100 becomes a desired color. For example, when the light from the LED element 2 is blue and the fluorescence emitted from the phosphor included in the wavelength conversion layer 11 is yellow, the light from the LED device 100 is white.

The wavelength conversion layer 11 may cover the LED element 2. For example, as shown in FIG. 1, the wavelength conversion layer 11 may cover the reflective layer 21 together with the LED element 2.

The phosphor particles contained in the wavelength conversion layer 11 may be anything that is excited by the light emitted from the LED element 2 and emits fluorescence having a wavelength different from that of the emitted light from the LED element 2. For example, examples of phosphor particles that emit yellow fluorescence include YAG (yttrium, aluminum, garnet) phosphors. The YAG phosphor receives blue light (wavelength 420 nm to 485 nm) emitted from the blue LED element, and emits yellow fluorescence (wavelength 550 nm to 650 nm).

The phosphor particles are, for example, 1) An appropriate amount of flux (fluoride such as ammonium fluoride) is mixed with a mixed raw material having a predetermined composition, and pressed to form a molded body. 2) The obtained molded body is packed in a crucible and fired in air at a temperature range of 1350 to 1450 ° C. for 2 to 5 hours to obtain a sintered body.

A mixed raw material having a predetermined composition is obtained by sufficiently mixing oxides such as Y, Gd, Ce, Sm, Al, La, and Ga, or compounds that easily become oxides at high temperatures in a stoichiometric ratio. . Moreover, the mixed raw material which has a predetermined composition mixes the solution which dissolved 1) the rare earth elements of Y, Gd, Ce, and Sm in the acid in stoichiometric ratio, and oxalic acid, and obtains a coprecipitation oxide. 2) It can also be obtained by mixing this coprecipitated oxide with aluminum oxide or gallium oxide.

The kind of the phosphor is not limited to the YAG phosphor, and may be another phosphor such as a non-garnet phosphor that does not contain Ce.

The average particle diameter of the phosphor particles is preferably 1 μm to 50 μm, and more preferably 10 μm or less. The larger the particle size of the phosphor particles, the higher the light emission efficiency (wavelength conversion efficiency). On the other hand, when the particle diameter of the phosphor particles is too large, a gap generated at the interface between the phosphor particles and the binder becomes large. Thereby, the intensity | strength of the cured film of a wavelength conversion layer tends to fall. The average particle diameter of the phosphor particles refers to the value of D50 measured with a laser diffraction particle size distribution meter. Examples of the laser diffraction particle size distribution measuring device include a laser diffraction particle size distribution measuring device manufactured by Shimadzu Corporation.

The binder contained in the wavelength conversion layer 11 can be a transparent resin or a translucent ceramic. The transparent resin can be, for example, a silicone resin and an epoxy resin. When the binder is a transparent resin, the thickness of the wavelength conversion layer 11 is preferably about 25 μm to 5 mm. If the wavelength conversion layer 11 is too thick, the concentration of the phosphor particles becomes excessively low, and the phosphor particles may not be uniformly dispersed. The thickness of the wavelength conversion layer 11 means the maximum thickness of the wavelength conversion layer 11 formed on the light emitting surface of the LED element 2. The thickness of the wavelength conversion layer 11 can be measured with a laser holo gauge. When the binder is a transparent resin, the amount of phosphor particles contained in the wavelength conversion layer 11 is generally 5 to 15% by mass.

On the other hand, the translucent ceramic may be the same as the polysiloxane contained in the reflective layer. When the binder is polysiloxane, the thickness of the wavelength conversion layer 11 is preferably 5 to 200 μm. When the binder is polysiloxane and the wavelength conversion layer 11 is excessively thick, cracks or the like are likely to occur in the wavelength change layer 11. Even when the binder is polysiloxane, the thickness of the wavelength conversion layer 11 means the maximum thickness of the wavelength conversion layer 11 formed on the light emitting surface of the LED element 2. The thickness of the wavelength conversion layer 11 can be measured with a laser holo gauge.

Further, when the binder is polysiloxane, the amount of phosphor particles contained in the wavelength conversion layer 11 is preferably 60 to 95% by mass. The higher the concentration of the phosphor particles contained in the wavelength conversion layer 11, the better. If the concentration of the phosphor particles is high, the strength of the wavelength conversion layer 11 tends to increase. However, if the content ratio of the translucent ceramic is too small, the phosphor particles may not be sufficiently retained.

FIG. 1 shows an example in which the wavelength conversion layer is disposed so as to be in contact with the LED element, but the present invention is not limited to this, and the wavelength conversion layer may not be in contact with the LED element. In other words, the wavelength conversion layer only needs to be arranged in the light emitting direction of the LED element; even if a space is formed between the wavelength conversion layer and the LED element or other layers are arranged. Good. Examples of the other layers may be a light-transmitting layer or a sealing layer containing polysiloxane or the like contained in the above-described reflective layer as a binder.

3. Manufacturing Method of LED Device The aforementioned LED device can be manufactured through the following three steps.
(1) The process of preparing the board | substrate with which the LED element was mounted (2) The process of apply | coating the above-mentioned coating liquid to at least circumference | surroundings of the LED element of the board | substrate with which the LED element was arrange | positioned (3) The coating liquid apply | coated on the board | substrate The process of forming a reflective layer by curing

The LED device manufacturing method may further include (4) a step of forming a wavelength conversion layer containing phosphor particles on the reflective layer as necessary.

(1) LED element preparation process In an LED element preparation process, the board | substrate with which the LED element and the electrode were connected is prepared. For example, it may be a step of preparing a substrate having the above-described electrodes, fixing the LED element to the substrate, and connecting the electrode of the substrate to the cathode electrode and the anode electrode of the LED element. The method for connecting the LED element and the electrode and the method for fixing the LED element to the substrate are not particularly limited, and may be the same as a conventionally known method.

(2) Coating liquid coating process The coating liquid coating process is a process in which the coating liquid is applied to at least the surrounding area of the LED element on the substrate, that is, the area where the reflective layer is formed. The coating liquid of the present invention has a low solvent content and a relatively high viscosity. Accordingly, it is possible to form a coating film having a certain thickness or more with a small number of coatings. For example, a coating film having a thickness after curing of 40 μm or more can be formed by application twice or less, preferably once.

The method for applying the coating solution is not particularly limited as long as it is a method capable of applying the coating solution to a desired region, and known coating methods such as blade coating, spin coating coating, dispenser coating, spray coating, and inkjet method coating. It can be. Of these, dispenser coating is preferred because a highly viscous coating solution can be stably coated.

(3) Coating solution curing step The coating solution curing step may be a step of forming a reflective layer by heating and curing a coating solution coated on a substrate. In the coating solution curing step, the solvent in the coating solution is removed and the alkoxysilane compound is hydrolyzed and polycondensed.

The temperature at which the coating solution is cured is preferably 20 to 200 ° C., more preferably 25 to 150 ° C. If the heating temperature is less than 20 ° C, the solvent in the coating film may not be sufficiently evaporated. When the heating temperature is less than 100 ° C., the alkoxysilane compound may not be sufficiently polymerized.

Since the coating solution has a small solvent content ratio and a small volume change before and after curing, the stress generated in the coating film during curing can be reduced. Moreover, since the ratio of the tetrafunctional silane compound contained in the coating liquid is small and the hardness of the cured product does not become too high, the stress generated in the coating film can be relaxed. As a result, the occurrence of cracks during curing can be satisfactorily suppressed.

(4) Wavelength conversion layer formation process A wavelength conversion layer formation process may be a process of apply | coating and hardening the composition for wavelength conversion layers containing fluorescent substance particle so that an LED element may be covered. The composition for wavelength conversion layer contains phosphor particles and a binder component.

The binder component can be a transparent resin contained in the wavelength conversion layer or a precursor thereof, or a polysiloxane precursor (alkoxysilane compound). Moreover, a solvent is contained in the composition for wavelength conversion layers as needed. When the binder component is the aforementioned transparent resin or a precursor thereof, the solvent is a hydrocarbon such as toluene or xylene; a ketone such as acetone or methyl ethyl ketone; an ether such as diethyl ether or tetrahydrofuran; propylene glycol monomethyl ether acetate, ethyl It may be an ester such as acetate. On the other hand, when the binder component is an alkoxysilane compound, the solvent can be the same as the organic solvent contained in the coating solution.

The mixing of the composition for wavelength conversion layer can be performed, for example, with a stirring mill, a blade kneading stirring device, a thin-film swirling disperser, or the like. By adjusting the stirring conditions, the precipitation of the phosphor particles in the wavelength conversion layer composition is suppressed.

The method for applying the composition for wavelength conversion layer is appropriately selected depending on the type of binder, and can be, for example, dispenser application or spray application. Moreover, this is hardened after application | coating of the composition for wavelength conversion layers. The curing method and curing conditions of the wavelength conversion layer composition are appropriately selected depending on the type of resin. An example of the curing method is heat curing.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

1. Preparation of Silane Compound Solution <Silane Compound Solution 1>
19.5 mass% of tetramethoxysilane (76.0 mol% with respect to the entire silane compound), 5.5 mass% of methyltrimethoxysilane (24.0 mol% with respect to the entire silane compound), 60 mass% of methanol, 14.99% by mass of water and 0.01% by mass of nitric acid were mixed and stirred at 23 ° C. for 3 hours, and then reacted at 26 ° C. with stirring for 3 days to obtain a silane compound solution 1 containing a polysiloxane oligomer. Obtained.

<Silane compound solutions 2-11, 14-20>
Silane compound solutions 2 to 11 and 14 to 20 were obtained in the same manner as silane compound solution 1 except that the composition was changed to the composition shown in Table 1.

<Silane compound solution 12>
A silane compound solution 12 is obtained by mixing 15.5% by mass of tetramethoxysilane, 9.5% by mass of methyltrimethoxysilane, 60% by mass of methanol, 14.99% by mass of water and 0.01% by mass of nitric acid. It was.

<Silane compound solution 13>
Water and dilute nitric acid were added to 0.1 mol of ethyltrimethoxysilane to prepare a molar ratio of alkoxide: water: dilute nitric acid of 1: 3: 0.002. This solution was stirred in a sealed container at 20 ° C. for 3 hours, and then further aged at 60 ° C. for 48 hours to cause hydrolysis and polycondensation reactions to proceed. The upper phase rich in methanol produced by the reaction was removed and dried at 60 ° C. for 3 hours to obtain a silane compound solution 13.

The weight average molecular weight of the polysiloxane oligomer in the obtained silane compound solution and measurement of solid Si-NMR were performed by the following methods.

(Weight average molecular weight of polysiloxane oligomer)
The weight average molecular weight of the polysiloxane oligomer in the obtained silane compound solution was measured by GPC using polystyrene equivalent weight average molecular weight.

(Measurement of solid Si-NMR)
Solid Si-NMR measurement was performed using a solid obtained by curing the obtained silane compound solution at 150 ° C. as a sample. Then, the ratio R4 / R3 of the Q component and the T component was obtained from the area ratio of the peak corresponding to the Q component and the peak corresponding to the T component. Further, the amount R2 of the D component was determined from the area of the peak corresponding to the D component.

The compositions of the resulting silane compound solutions 1 to 20 are shown in Table 1.

2. Preparation of adjustment liquid <Preparation of adjustment liquids 1 to 24>
Each component was mixed at the composition ratio shown in Table 2 to obtain Adjustment Solutions 1 to 24. Each component used for preparation of the adjustment liquid is as follows.

(solvent)
EG: ethylene glycol PG: propylene glycol BD: 1,3-butanediol IPA: isopropyl alcohol EtOH: ethanol

(Inorganic particles 1)
Silicia 470: Silica (Silicia 470, manufactured by Fuji Silysia Chemical) average particle size of 14 μm
SP-1: Silica (Microbead SP-1, manufactured by JGC Catalysts & Chemicals) average particle size of 5 μm
VM2270: Silica (VM-2270, manufactured by Dow Corning) average particle size of 5 to 15 μm
SS-50F: Silica (Nip seal SS-50F, manufactured by Tosoh Silica) Average particle size 1.2 μm
Alu-C: Alumina (AEROXIDE Alu-C, Nippon Aerosil) primary particle size 13nm
A300: Silica (Nippon Aerosil Co., Ltd.) average primary particle size: 7 nm
RX300: Silica (manufactured by Nippon Aerosil Co., Ltd.) Average primary particle size: 7 nm
F3: Silica (high silica F3, manufactured by Nichetsu) Average particle diameter: 3 μm

(Inorganic particles 2)
ZR-210: ZrO ₂ particles (TECNADIS-Zr-210, manufactured by TECNAN) Average particle size: 10 to 15 nm
Ti-210: TiO ₂ particles (TECNADIS-TI-210, manufactured by TECNAN) average particle diameter of 10 to 15 nm

(Layered clay mineral)
MK-100: Synthetic mica (Micromica MK-100, manufactured by Corp Chemical)
ME-100: Synthetic mica (Somasif ME-100, manufactured by Corp Chemical)
SWN: Smectite (Lucentite SWN, manufactured by Corp Chemical)
SPN: Smectite (Lucentite SPN, manufactured by Corp Chemical)
Kunipia F: Montmorillonite (Kunipia F, manufactured by Kunimine Industries)
FSE: Synthetic mica (FSE, manufactured by Sanshin Mining Co., Ltd.)
SA-1: Saponite-like substance (Smecton SA-1, manufactured by Kunimine Industries)
HVP: Natural bentonite (Esven NE, manufactured by Hojun Co.)
NE: Bentonite (Bengel HVP, manufactured by Hojun Co.)
Imogolite

(Silane coupling agent)
KBM-403: 3-glycidoxypropyltrimethoxysilane (KBM-403, manufactured by Shin-Etsu Silicone)
KBM-903: 3-aminopropyltrimethoxysilane (KBM-903, manufactured by Shin-Etsu Silicone)
KBM-802: 3-mercaptopropylmethyldimethoxysilane (KBM-802, manufactured by Shin-Etsu Silicone)
KBE-846: Bis (triethoxysilylpropyl) tetrasulfide (KBE-846, manufactured by Shin-Etsu Silicone)

3. Preparation and Evaluation of Coating Solution [Examples 1 to 70 and Comparative Examples 1 to 10]
The white pigment, silane compound solution and adjustment liquid shown in Tables 3 to 6 were mixed at a mixing ratio shown in Tables 3 to 6 with a stirrer to obtain a coating solution. The following was used as the white pigment.

(White pigment)
Titanium oxide: SX-3103 Made by Sakai Chemical Industry Co., Ltd. Titanium oxide: D-918 Made by Sakai Chemical Industry Co., Ltd. Titanium oxide: JR Teica Co., Ltd. Titanium oxide: JR-405 Made by Teika Co., Ltd. Titanium oxide: CR-93 Made by Ishihara Sangyo Titanium oxide: CR-95 Made by Ishihara Sangyo Aluminum oxide: HD-11 Made by Nikkato Barium sulfate: NFJ-3-1999 Made by Yamanishi Boron nitride: AP-100S Made by MARUKA

The viscosity and coating amount stability of the obtained coating solution, the volume ratio B / A before and after curing, crack resistance, reflectance and adhesion were evaluated by the following methods.

<Viscosity>
The viscosity of the coating solution was measured using a vibration viscometer VISCOMATE MODEL VM-10A (manufactured by Seconic). The measurement temperature was 25 ° C., and the measured value after 1 minute was used after the vibrator was immersed in the liquid.

<Coating amount stability>
The syringe of the dispenser was filled with the mixed liquid, and dispensed 10 times continuously under certain conditions, and the total mass of the dropped liquid was determined. Subsequently, the same operation was performed every 10 minutes while holding the syringe as it was, and after 10 hours, dispensing was performed 10 times continuously under the same conditions, and the total mass of the dropped liquid was obtained.
When the total mass of the liquid dropped in the first 10 times was A, and the total mass of the liquid dropped in 10 times after 4 hours was B, the mass change rate was calculated by the following formula.
Mass change rate = ((BA) / A) × 100%

The coating amount stability was evaluated according to the following criteria.
○: Mass change rate was less than 3%.
Δ: Mass change rate was 3% or more and less than 6%.
X: Mass change rate was 6% or more.

<Volume ratio B / A>
The volume ratio before and after curing was measured by the following procedure.
1) The volume of the coating solution was measured with a graduated cylinder in a 25 ° C. atmosphere, and was defined as volume A before curing.
2) After coating the coating solution on a Teflon (registered trademark) substrate, the coating film was heated and cured at 150 ° C. for 1 hour, and then peeled off from the Teflon (registered trademark) substrate to obtain a cured product. The weight of the obtained cured product was measured in an atmosphere at 25 ° C. Furthermore, the specific gravity of the cured product was measured in an atmosphere at 25 ° C. by the Archimedes method. And the volume B of hardened | cured material was computed from the weight of the obtained hardened | cured material, and the specific gravity measured by the Archimedes method.
3) The volume ratio B / A before and after curing was calculated from the volume A measured in 1) and the volume B calculated in 2).

<Evaluation of film formability (cracks during film formation)>
The coating solution was applied once to a transparent 1 mm glass plate and cured by heat treatment at 150 ° C. for 1 hour to prepare a measurement sample having a reflective layer. The state of the reflective layer at this time was visually observed and evaluated according to the following criteria.
◎: Crack does not occur even when the film thickness is 60 μm ○: Crack occurs when the film thickness is 50 μm or more and less than 60 μm Δ: Crack occurs when the film thickness is 40 μm or more and less than 50 μm ×: Crack occurs when the film thickness is 40 μm

<Reflectance measurement 1>
The coating solution was applied once to a transparent 1 mm glass plate and cured by heat treatment at 150 ° C. for 1 hour to prepare a measurement sample having a reflective layer having a thickness of 20 μm. Then, the reflectance of each sample was measured with a spectrophotometer V-670 (manufactured by JASCO Corporation). Evaluation was performed according to the following criteria.
○: The reflectance at a film thickness of 20 μm is 95% or more ×: The reflectance at a film thickness of 20 μm is less than 95%

<Reflectance measurement 2>
The coating solution was applied once to a transparent 1 mm glass plate and cured by heat treatment at 150 ° C. for 1 hour to prepare a measurement sample having a reflective layer having a thickness of 60 μm. Then, the reflectance of each sample was measured with a spectrophotometer V-670 (manufactured by JASCO Corporation). Evaluation was performed according to the following criteria.
A: Reflectance is 98% or more at a film thickness of 60 μm. −: Cracks occur at a film thickness of 60 μm and are not evaluated.

<Tape peeling experiment>
A coating solution was applied on a silver plate and cured by heat treatment at 150 ° C. for 1 hour to prepare a measurement sample having a reflective layer having a thickness of 20 μm. The work of attaching Nichiban cello tape (registered trademark) (24 mm) to the formed reflective layer and immediately peeling it off was repeated 20 times. And the state of the reflective layer was observed with the microscope for every operation | work, and it judged as follows.
A: No peeling of reflective layer was observed after 20 times of operation, and nothing adhered to the surface of the tape. ○: No separation was observed after 10 times of operation, but after 20 times of operation, it was slightly peeled off. △: No peeling occurred, but after the first work, a small amount of white pigment powder adhered to the surface of the tape. X: The reflective layer was peeled off at the 10th working time.

Tables 3 to 6 show the evaluation results of the examples and comparative examples.

The cured products of the coating liquids of Examples 1 to 70 in which the composition of the silane compound satisfies

Formulas

1 and 2 and the volume ratio B / A before and after curing satisfies Formula 3 show high crack resistance and adhesion. It can also be seen that a high reflectance can be obtained.

On the other hand, the cured products of the coating solutions of Comparative Examples 1 to 5 whose composition in the silane compound does not satisfy Formula 2 have low crack resistance, and the cured products of the coating solutions of Comparative Examples 6 and 7 that do not satisfy Formula 1 It turns out that the nature is low. The cured product of the coating solution of Comparative Example 9 in which the volume ratio B / A before and after curing is too large has low crack resistance and reflectance, and the coating solution of Comparative Example 10 in which the volume ratio B / A before and after curing is too small is liquid. It turns out that discharge property is low.

From the comparison between Example 11 and Example 36, the coating liquid of Example 11 in which the silane compound has been oligomerized in advance has more cracks during curing than the coating liquid of Example 36 in which the silane compound is a monomer. It is highly suppressed and it can be seen that the resulting cured product has a high reflectance. This is presumably because the pre-oligomerized silane compound has less volume change due to polymerization than the monomeric silane compound.

From the comparison between Examples 12 and 19, it can be seen that when the volume ratio B / A is 0.25 or more, the reflectance at a film thickness of 60 μm is good. From the comparison between Examples 12 and 17, it can be seen that when the volume ratio B / A is 0.3 or more, the crack resistance is further increased.

This application claims priority based on Japanese Patent Application No. 2014-197072 filed on September 26, 2014. The contents described in the application specification and the drawings are all incorporated herein.

DESCRIPTION OF SYMBOLS 1 Substrate 2 LED element 3 Electrode 4 Metal wire 10A Light extraction surface 11 Wavelength conversion layer 21 Reflective layer 100 LED device

Claims

A coating liquid containing a white pigment, a silane compound, and a solvent,
When the ratio of the bifunctional silane compound in the total amount of the silane compound is R2 (mol%), the ratio of the trifunctional silane compound is R3 (mol%), and the ratio of the tetrafunctional silane compound is R4 (mol%), the following: Satisfy both the conditions of Equation 1 and Equation 2,
0 ≦ R2 <40 (Formula 1)
0 ≦ R4 / R3 ≦ 2 (Formula 2)
When the volume of the coating solution is A and the volume of the cured product obtained by heat-curing the coating solution at 150 ° C. for 1 hour is B, the volume ratio B / A before and after curing satisfies the condition of the following formula 3. Application liquid.
0.2 ≦ B / A ≦ 0.7 (Formula 3)
The coating liquid according to claim 1, wherein the molar ratio of the silane compound satisfies the condition of the following formula 4.
0 ≦ R4 / R3 ≦ 1.5 (Formula 4)
The coating liquid according to claim 1 or 2, wherein the volume ratio B / A before and after curing satisfies the condition of the following formula 5.
0.25 ≦ B / A ≦ 0.6 (Formula 5)
The coating solution according to any one of claims 1 to 3, wherein the solvent contains at least one of a monovalent alcohol and a dihydric or higher polyhydric alcohol.
The coating solution according to any one of claims 1 to 4, wherein at least one selected from the group consisting of the bifunctional silane compound, the trifunctional silane compound, and the tetrafunctional silane compound is polymerized in advance.
The coating solution according to any one of claims 1 to 5, further comprising inorganic particles or clay mineral particles.
The coating solution according to any one of claims 1 to 6, further comprising a silane coupling agent.
The coating solution according to any one of claims 1 to 7, wherein the viscosity is more than 5 mPa · s and not more than 2000 mPa · s.
A coating liquid containing a white pigment, a silane compound, and a solvent,
When the ratio of the bifunctional silane compound in the total amount of the silane compound is R2 (mol%), the ratio of the trifunctional silane compound is R3 (mol%), and the ratio of the tetrafunctional silane compound is R4 (mol%), the following: Satisfy both the conditions of Equation 1 and Equation 2,
0 ≦ R2 <40 (Formula 1)
0 ≦ R4 / R3 ≦ 2 (Formula 2)
A coating solution, wherein a content ratio of the solvent is in a range of 10 to 45% by mass with respect to the coating solution.
A substrate, an LED element disposed on the substrate, a reflective layer disposed at least around the LED element on the substrate, and a wavelength conversion layer disposed in a light emitting direction of the LED element. A method for manufacturing an LED device comprising:
Applying the coating liquid according to any one of claims 1 to 9 on the substrate;
Curing the applied coating solution to form the reflective layer.
Apply the coating solution once or twice,
The manufacturing method of the LED device of Claim 10 which hardens the said apply | coated coating liquid and forms the said reflection layer with a thickness of 40 micrometers or more.
A substrate; an LED element disposed on the substrate; a reflective layer disposed around the LED element on the substrate; and a wavelength conversion layer disposed in a light emission direction of the LED element. An LED device,
The LED device, wherein the reflective layer is a cured film of the coating liquid according to any one of claims 1 to 9.
The LED device according to claim 12, wherein the wavelength conversion layer is in contact with the LED element.
The LED device according to claim 12, wherein the reflective layer is further disposed between the substrate and the LED element.