JP6343947B2 - Polysilsesquioxane encapsulant composition for UV-LED and use of metal alkoxide therefor - Google Patents

Description

  The present invention relates to a polysilsesquioxane-based encapsulant composition for UV-LED and the use of a metal alkoxide therefor.

Patent Document 1 describes a sealing material obtained using aluminum acetylacetonate as a curing accelerator for a condensation silicone sealing material.

Japanese Patent Laid-Open No. 2007-112975

  However, since such a sealing material has absorption in the UV region, it is not always satisfactory as a sealing material for UV-LED.

The present invention includes the inventions described in [1] and [2] below.
[1] Use of a metal alkoxide as a curing accelerator for a polysilsesquioxane-based encapsulant for UV-LED in which the light transmittance at 260 nm of the cured product is 65% or more;
[2] A polysilsesquioxane encapsulant composition for UV-LED, comprising a polysilsesquioxane encapsulant and a metal alkoxide.

  By using the curing accelerator of the present invention, a polysilsesquioxane-based encapsulant composition suitable for sealing an element that emits light in the ultraviolet region (particularly the UV-C region) and the use of a metal alkoxide therefor are used. Provided.

It is an ultraviolet-visible transmittance | permeability measurement result of the hardened | cured material obtained in Example 1. FIG. It is an ultraviolet-visible transmittance | permeability measurement result of the hardened | cured material obtained by the comparative example 1.

  Hereinafter, the present invention will be described in detail.

<Polysilsesquioxane-based sealing material>
In the present invention, as the polysilsesquioxane-based encapsulant, for example, Amax Co., Ltd. website “polysilsesquioxane T-resin” <URL: http://www.azmax.co.jp/cnt_catalog_chemical/ and polysilsesquioxane described in pdf / attach_20110517_135825.pdf> and the like.

（一般式（１）中、Ｒ^１はそれぞれ独立してアルキル基を表し、Ｒ^２はそれぞれ独立してアルコキシ基、又は水酸基を表し、ｐ^１、ｑ^１、ａ^１、及びｂ^１は、［ｐ^１＋ｂ^１×ｑ^１］：［ａ^１×ｑ^１］＝１：０．２５〜９となる任意の正数を表す。） Specific examples of the polysilsesquioxane-based sealing material include a sealing material containing the resin A having an organopolysiloxane structure represented by the formula (1).

(In General Formula (1), each R ¹ independently represents an alkyl group, each R ² independently represents an alkoxy group or a hydroxyl group, and p ¹ , q ¹ , a ¹ , and b ¹ are p ¹ + b ¹ × q ¹ ]: [a ¹ × q ¹ ] = 1: represents an arbitrary positive number that satisfies 0.25 to 9.

（一般式（２）中、Ｒ^１及びＲ^２は、前記一般式（１）と同じ意味を表し、ｐ^２、ｑ^２、ｒ^２、ａ^２、及びｂ^２は、［ａ^２×ｑ^２］／［（ｐ^２＋ｂ^２×ｑ^２）＋ａ^２×ｑ^２＋（ｒ^２＋ｑ^２）］＝０〜０．３となる任意の０以上の数を表す。） More preferably, it further includes an oligomer B having an organopolysiloxane structure represented by the formula (2), and the mixing ratio of the resin A and the oligomer B is such that the resin A: oligomer B = 100: 0.1-20 (mass ratio). More preferably, By using the resin A as a main component, there is an effect of suppressing deterioration due to ultraviolet light or improving heat resistance.

(In General Formula (2), R ¹ and R ² represent the same meaning as in General Formula (1), and p ² , q ² , r ² , a ² , and b ² are [a ² × q ² ] / [(P ² + b ² × q ² ) + a ² × q ² + (r ² + q ² )] = 0 represents an arbitrary number of 0 or more that is 0 to 0.3.)

The alkyl group represented by R ¹ may be linear or branched, and may have a cyclic structure, but may be a linear or branched alkyl group. Are preferable, and a linear alkyl group is more preferable. Moreover, although the carbon number of the said alkyl group is not specifically limited, A C1-C10 alkyl group is preferable, A C1-C6 alkyl group is more preferable, A C1-C3 alkyl group is More preferably, carbon number 1 is particularly preferable.

R ² each independently represents an alkoxy group or a hydroxyl group.

When R ² is an alkoxy group, the alkoxy group may be linear or branched, and may have a cyclic structure, but may be linear or branched. Are more preferable, and a linear alkoxy group is more preferable. Moreover, although carbon number of the said alkoxy group is not specifically limited, A C1-C3 alkoxy group is preferable, C1-C2 is more preferable, and C1-C1 is especially preferable.

The plurality of R ¹ and R ² may be the same type of group or different from each other.

The resin A has at least one selected from the group consisting of a methyl group and an ethyl group as R ¹ , and R ² from the group consisting of a methoxy group, an ethoxy group, an isopropoxy group, and a hydroxyl group Those having one or more selected are preferable, R ¹ has one or more selected from the group consisting of a methyl group and an ethyl group, and R ² has a methoxy group, an ethoxy group, And those having one or more selected from the group consisting of isopropoxy groups and a hydroxyl group are more preferred.

  The weight average molecular weight (Mw) of the resin A is 1500 or more and 8000 or less. When the weight average molecular weight of the resin A is too small, the volume shrinkage rate at the time of curing increases, so that the stress generated in the sealing body increases and cracks are likely to occur. On the other hand, if it is too large, the viscosity of the encapsulated body before curing and the viscosity increase at the time of curing increase, and bubbles tend to be generated when alcohol or water generated by the condensation reaction volatilizes. The weight average molecular weight of the resin A is preferably 1500 or more and 7000 or less, and more preferably 2000 or more and 5000 or less.

  Resin A can be synthesized using an organosilicon compound having a functional group capable of generating a siloxane bond as a starting material, corresponding to each of the repeating units described above. Examples of the “functional group capable of generating a siloxane bond” include a halogen atom, a hydroxyl group, and an alkoxy group. As the organosilicon compound, for example, organotrihalosilane or organotrialkoxylane can be used as a starting material. Resin A can be synthesized by reacting such starting materials by a hydrolysis-condensation method at a ratio corresponding to the abundance ratio of each repeating unit. In addition, as the resin A synthesized in this manner, those commercially available as a silicone resin or an alkoxy oligomer can be used.

The oligomer B has at least one selected from the group consisting of a methyl group and an ethyl group as R ¹ , and R ² is selected from the group consisting of a methoxy group, an ethoxy group, an isopropoxy group, and a hydroxyl group It is preferable that R ¹ is a methyl group, and R ² has a methoxy group or a hydroxyl group.

  The weight average molecular weight of the oligomer B is less than 1500. If the weight average molecular weight of the oligomer B is too large, the crack resistance of the encapsulant after curing may be insufficient. The weight average molecular weight of the oligomer B is preferably 200 or more and less than 1500, and more preferably 250 to 1000.

  The oligomer B can be synthesized using an organosilicon compound having a functional group capable of generating a siloxane bond, corresponding to each of the above-described repeating units constituting the oligomer B. “Functional group capable of forming a siloxane bond” has the same meaning as described above. As the organosilicon compound, for example, organotrihalosilane or organotrialkoxylane can be used as a starting material. The silicone resin can be synthesized by reacting such starting materials by a hydrolysis condensation method at a ratio corresponding to the abundance ratio of each repeating unit.

  The difference in the weight average molecular weight from that of the resin A can be controlled, for example, by controlling the reaction temperature at the time of subjecting the starting material to a hydrolytic condensation reaction or the rate of addition of the starting material into the reaction system. As the silicone resin synthesized in this manner, those commercially available as a silicone resin or an alkoxy oligomer can be used.

  The weight average molecular weights of the resin A and the oligomer B can be measured using polystyrene as a standard using a commercially available GPC apparatus.

  The polysilsesquioxane-based encapsulant before curing may be used after being dissolved in a solvent in order to facilitate potting on an element placed on the substrate. At this time, the viscosity of the obtained solution may be adjusted to be 10 mPas to 10,000 mPas.

  The solvent is not particularly limited as long as it can dissolve the pre-curing sealing material used, for example, ketone solvents such as acetone and methyl ethyl ketone; alcohol solvents such as methanol, ethanol, isopropyl alcohol, and normal propyl alcohol. Hydrocarbon solvents such as hexane, cyclohexane, heptane and benzene; acetate solvents such as methyl acetate and ethyl acetate; ether solvents such as dimethyl ether and tetrahydrofuran; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, Ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monoethyl hexyl ether, ethylene glycol monophenyl ether Ter, ethylene glycol monobenzyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, diethylene glycol monoethyl hexyl ether, diethylene glycol monophenyl ether, diethylene glycol monobenzyl ether, propylene glycol monomethyl ether , Propylene glycol monoethyl ether, propylene glycol monoisopropyl ether, propylene glycol monobutyl ether, propylene glycol monohexyl ether, propylene glycol monoethyl hexyl ether, propylene glycol monomer Phenyl ether, propylene glycol monobenzyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoisopropyl ether, dipropylene glycol monobutyl ether, dipropylene glycol monohexyl ether, dipropylene glycol monoethyl hexyl ether, di Glycol ether solvents such as propylene glycol monophenyl ether and dipropylene glycol monobenzyl ether; ethylene glycol monoethyl ether acetate, ethylene glycol monoisopropyl ether acetate, ethylene glycol monobutyl ether acetate, ethylene glycol monohexyl ether acetate, ethylene glycol monoethyl And glycol ester solvents obtained by adding an acetic acid group to the above-described glycol ether solvents such as tilhexyl ether acetate, ethylene glycol monophenyl ether acetate, and ethylene glycol monobenzyl ether acetate.

<Curing accelerator>
The curing accelerator in the present invention is a metal alkoxide. The metal alkoxide is a compound represented by the following formula (3).
M (OR) _n (3)
(In the formula, M represents a metal ion. R represents an organic group. N represents the valence of the metal ion.)
Examples of the metal (M) in the metal alkoxide include aluminum, gallium, titanium, zirconium, hafnium, and zinc. Among these, aluminum and zirconium are preferable and aluminum is more preferable from the viewpoint of emitting light in the ultraviolet region (particularly the UV-C region). Examples of the alkoxy group (OR) include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a sec-butoxy group, a tert-butoxy group, and the like, and an isopropoxy group is preferable. As the metal alkoxide, aluminum alkoxide or zirconium alkoxide is preferable. Examples of the aluminum alkoxide include aluminum triethoxide, aluminum triisopropoxide, aluminum trisec-butoxide, aluminum tritert-butoxide and the like. Examples of zirconium isopropoxide include zirconium tetraisopropoxide and zirconium trisec-butoxide.

  The curing accelerator may be used after being dissolved in an organic solvent. The solvent used in this case may be any solvent that dissolves the organometallic complex, and is preferably an alcohol, ester, or ether. In general, the concentration of the curing accelerator is preferably 0.01% to 10%.

  The usage-amount of a hardening accelerator is 10 ppm-500 ppm (parts per million by weight) with respect to a polysilsesquioxane type | system | group sealing material, Preferably it is the range of 10 ppm-200 ppm. From the viewpoint of increasing the hardness of the cured product, it is preferably 10 ppm or more, and from the viewpoint of emitting light in the ultraviolet region (particularly the UV-C region), it is preferably 500 ppm or less.

  The effect accelerator is preferably prepared as a solution different from the resin A and the oligomer B, and these solutions are preferably mixed before use.

<Curing sealing material>
The use of the present invention is usually carried out by potting a pre-curing encapsulant containing the polysilsesquioxane-based encapsulant and a curing accelerator on an element placed on a substrate and then curing. . That is, the sealing method of the element for UV-LED by use of the present invention is the first step of installing the element on the substrate, the polysilsesquioxane-based sealing material and the following solvent on the element installed on the substrate in the first step. a second step of potting a polysilsesquioxane-based encapsulant composition containing a, and a step of curing the polysilsesquioxane-based encapsulant potted in the second step.

  The element is placed on the substrate by a conventional method. Of course, you may install other structures normally required for a semiconductor light-emitting device, such as an electrode and wiring.

  The potting is usually performed by supplying a sealing material before curing onto a substrate with a dedicated dispenser. The amount of the sealing material to be supplied before curing varies depending on the structure, area, volume, and other electrode and wire wiring structures of the substrate and elements, but these elements and wire wirings are embedded and the light emitting element is covered. The thickness of the sealing material is preferably an amount that can be made as thin as possible, and more preferably an amount that makes the thickness 2 mm or less. When the sealing material on the element is thick, the sealing material gradually deteriorates due to heat and ultraviolet rays generated when the element emits light, and the transparency of the sealing material is lost due to discoloration. Luminance decreases over time. In particular, since the tendency is remarkable in a power LED for visible light having a light emission output current of 100 mA or more and a UV-LED that emits ultraviolet light having a wavelength of 350 nm or less, which has been developed in recent years, the thickness of the sealing material on the light emitting element is Thinning is effective.

  As curing conditions, a temperature and a time at which a normal polycondensation reaction occurs may be set. Specifically, the temperature is preferably 100 to 200 ° C. and more preferably 120 to 200 ° C. in air at atmospheric pressure. The time is preferably about 1 to 5 hours. Further, in order to effectively promote the volatilization of the residual solvent in the encapsulant and the polycondensation reaction, the curing temperature may be increased stepwise to be cured.

The apparatus and measurement conditions used for the UV-visible transmittance measurement described in the following examples are as follows.
<Ultraviolet visible transmittance measurement>
Device name: UV-3600 manufactured by Shimadzu Corporation
Attachment: Integrating sphere ISR-3100
Measurement wavelength: 220 to 800 nm
Background measurement: Atmospheric measurement speed: Medium speed

As the resin A, a resin (A-1) having an organopolysiloxane structure represented by the formula (1) (Mw = 3500, in the formula (1), R ¹ = methyl group, R ² = methoxy group or hydroxyl group ) Was used. Table 1 shows the abundance ratio of each repeating unit of the resin A-1. Further, as the oligomer B, an oligomer having an organopolysiloxane structure represented by the formula (2) (Mw = 450, R1 = methyl group, R2 = methoxy group in the general formula (2)) was used. Table 2 shows the abundance ratio of each repeating unit of the oligomer B-1.

Example 1
135 g of the resin (A-1) and 72.7 g of isopropyl alcohol were added to a flask placed in a water bath, and the resin (A-1) was dissolved by heating and stirring until the internal temperature reached 85 ° C. . Next, 15 g of the oligomer (B-1) was added and stirred for 1 hour or longer to dissolve the oligomer (B-1) to obtain a mixture.
After adding 47.2 g of 2-butoxyethyl acetate to the obtained mixture, isopropyl alcohol was added using an evaporator until the isopropyl alcohol concentration became 1% by mass or less under the conditions of a temperature of 80 ° C. and a pressure of 4 kPaA. The polysilsesquioxane-based sealing material composition (α1) having a mixing ratio of 90:10 between the resin (A-1) and the oligomer (B-1) was distilled off.

  With respect to 100 parts by mass of the polysilsesquioxane-based sealing material composition (α1), an aluminum triisopropoxide 0.1 wt% isopropyl alcohol solution is used so that the aluminum triisopropoxide is 100 ppm with respect to α1. And sufficiently agitated and mixed to obtain a polysilsesquioxane-based encapsulant composition (α1-1). Thereafter, about 3.8 g of the obtained mixture was put into an aluminum cup, heated in an oven at a rate of 3.7 ° C./minute from room temperature to 150 ° C., and left at 150 ° C. for 5 hours. A cured product of the silicone resin composition (α1-1) was obtained. The thickness of the obtained cured product was 1.7 mm. FIG. 1 shows the results of measuring the transmittance of the cured product. The transmittance at 260 nm was 70%.

Comparative Example 1
Methyltrimethoxysilane 1 2. 7 g, dimethyldimethoxysilane 1 1. 2 g, methanol 3. 3 g, water 8. 1 g and 4.8 g of a 5% by mass acetylacetone aluminum salt methanol solution were sealed in a flask and heated with a stirrer for 8 hours in a 50 ° C. hot water bath, then returned to room temperature to prepare a resin solution. did.
7.3 g of this resin liquid was put in a Teflon (registered trademark) petri dish having a diameter of 5 cm, heated at 40 ° C. for 4 hours, then heated to 65 ° C. over 3 hours, then heated to 150 ° C. over 1 hour, A cured product was obtained by holding at 3 ° C. for 3 hours. The thickness of the cured product at this time was 0.9 mm. FIG. 1 shows the results of measuring the transmittance of the cured product. The transmittance at 260 nm was 0%.

Claims (2)

A metal alkoxide represented by the following formula (3) as a curing accelerator for a polysilsesquioxane-based encapsulant for UV-LED containing the following resin A having a light transmittance of 260% or more at 260 nm of the cured product Of 10 ppm to 500 ppm (parts per million by weight) with respect to the polysilsesquioxane-based sealing material .
<Resin A>
Resin having organopolysiloxane structure represented by formula (1)

(In General Formula (1), each R ¹ independently represents an alkyl group, each R ² independently represents an alkoxy group or a hydroxyl group, and p ¹ , q ¹ , a ¹ , and b ¹ are p ¹ + b ¹ × q ¹ ]: [a ¹ × q ¹ ] = 1: represents an arbitrary positive number that satisfies 0.25 to 9.
M (OR) _n (3)
(In the formula, M represents a metal ion. R represents an organic group. N represents the valence of the metal ion.) Look containing a metal alkoxide represented by the polysilsesquioxane-based sealing material and the following formula (3) containing the following resin A, a metal alkoxide represented by the following formula (3) is, polysilsesquioxane-based The polysilsesquioxane type | system | group sealing material composition for UV-LED which is 10 ppm-500 ppm (parts per million by weight) with respect to the sealing material.
<Resin A>
Resin having organopolysiloxane structure represented by formula (1)

(In General Formula (1), each R ¹ independently represents an alkyl group, each R ² independently represents an alkoxy group or a hydroxyl group, and p ¹ , q ¹ , a ¹ , and b ¹ are p ¹ + b ¹ × q ¹ ]: [a ¹ × q ¹ ] = 1: represents an arbitrary positive number that satisfies 0.25 to 9.
M (OR) _n (3)
(In the formula, M represents a metal ion. R represents an organic group. N represents the valence of the metal ion.)

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