Addition-curable siloxane composition

Abstract

The present invention relates to an addition-curable siloxane composition comprising: a first organopolysiloxane which contains aryl groups and has a refractive index of 1.48 to 1.50 at a wavelength of 589 nm; a second organopolysiloxane which contains aryl groups and has a refractive index of 1.43 to 1.47 at a wavelength of 589 nm; a third organopolysiloxane which does not contain aryl groups and contains alkenyl groups directly bonded to silicon; an organohydrogenpolysiloxane which contains hydrogen groups directly bonded to silicon and has a refractive index of 1.43 to 1.50 at a wavelength of 589 nm; and silica; and an electronic / electrical device which comprises a cured product produced from the addition-curable siloxane composition.

Description

[Technical Field]

[0001] The present invention relates to an addition-curable siloxane composition that has an appropriate viscosity, excellent flowability, and excellent thixotropy, and produces a cured film that is excellent in transparency, hardness, and adhesive strength. [Background technology]

[0002] Epoxy resins have traditionally been used as encapsulants for light-emitting diodes (LEDs). While epoxy resins have excellent light transmittance, their high elasticity can lead to cracks between wires, chips, and / or epoxy resin under various temperature conditions and temperature changes, resulting in wire bond breakage and reduced light-emitting efficiency due to the breakdown of the crystalline structure of the semiconductor material. Furthermore, epoxy resins lack sufficient heat and light resistance to brighter, shorter wavelength light. Therefore, when ultraviolet light or other light penetrates epoxy resins, the organic polymer bonds are destroyed, significantly reducing the resin's optical and chemical properties. As a result, epoxy resin encapsulants turn yellow when exposed to ultraviolet light, affecting the hue of the light and shortening the lifespan of the light-emitting device.

[0003] To address these issues, the use of silicone-based resins as LED encapsulants has been proposed. Compared to organic resin-containing compositions, silicone-based resin-containing compositions are transparent and offer superior heat and weather resistance. They are also less susceptible to discoloration and physical degradation, making them ideal for use as LED encapsulants. While silicone-based resin-containing compositions offer superior mechanical strength and chemical stability, they have limitations in terms of achieving high brightness.

[0004] As an alternative to this, Japanese Patent No. 4009067 (Patent Document 1) discloses an addition-curable silicone resin composition containing (A) an organopolysiloxane containing a phenyl group and two or more alkenyl groups per molecule, (B) an organohydrogenpolysiloxane containing a phenyl group and two or more SiH groups per molecule, and (C) a catalyst for a hydrosilylation reaction. Specifically, the composition of Patent Document 1 contains a specific organopolysiloxane having phenyl groups and alkenyl groups, and a specific organohydrogenpolysiloxane having phenyl groups, because this increases the siloxane crosslink density and π-π interactions between aromatic rings are important for improving the refractive index of the cured product.

[0005] However, since the composition of Patent Document 1 lacks thixotropy, it tends to spread when dispensed and is unable to maintain its shape independently, which means that a dam must first be formed before dispensing the composition on a wall-like structure such as a surface mount device (SMD) light-emitting diode (LED) or a chip on board (COB) LED. Furthermore, the cured product obtained by dispensing the composition on an SMD-type or COB-type LED package has a flat surface or a very low aspect ratio, resulting in poor light diffusion and limiting its use.

[0006] Therefore, there is a need for research and development of addition-curable siloxane compositions that have appropriate viscosity, excellent fluidity, and excellent thixotropy, and that produce cured films with excellent transparency, hardness, and adhesive strength, making them suitable as sealing materials for LED elements. Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, the present invention aims to provide an addition-curable siloxane composition that has appropriate viscosity, excellent fluidity, and excellent thixotropy, and produces cured films with excellent transparency, hardness, and adhesive strength, making it suitable as a sealing material for LED elements. [Means for solving the problem]

[0008] The present invention provides a first organopolysiloxane that contains an aryl group and has a refractive index of 1.48 to 1.50 at a wavelength of 589 nm; a second organopolysiloxane containing an aryl group and having a refractive index at a wavelength of 589 nm of 1.43 to 1.47; a third organopolysiloxane that does not contain aryl groups and that contains alkenyl groups bonded directly to silicon; An organohydrogenpolysiloxane containing hydrogen groups directly bonded to silicon and having a refractive index of 1.43 to 1.50 at a wavelength of 589 nm; and silica; and

[0009] The present invention also provides an electronic / electrical device comprising a cured product prepared by curing the addition-curable siloxane composition. [Effects of the Invention]

[0010] The addition-curable siloxane composition according to the present invention has appropriate viscosity, excellent fluidity, and excellent thixotropy, resulting in excellent transparency of the cured film, making it highly suitable as an encapsulant for light-emitting diodes with a self-dome shape even on flat substrates without walls or dams. Furthermore, the addition-curable siloxane composition also produces cured films with excellent hardness and adhesive strength, making it applicable in a variety of fields, including encapsulants for LED devices, adhesives, coatings, potting agents, and sealants. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described in detail below.

[0012] The relationship between the structure and common names of common polysiloxanes is as follows:

[0013] (R3SiO 1 / 2 )a Unit: M unit (R2SiO 2 / 2 ) b Unit: D unit (RSiO 3 / 2 ) c Unit: T unit (SiO 4 / 2 ) d Unit: Q unit In the present specification, M unit, D unit, T unit and Q unit, which are conventionally used in the art, are used in combination.

[0014] The "refractive index" of the organopolysiloxane of the present invention can be measured by a method well known in the art, and may be, for example, a value measured using a refractometer on the liquid organopolysiloxane before curing. As an example, the refractive index may be a value measured at a wavelength of 589 nm using an Abbe refractometer at 25°C.

[0015] In addition, the content of functional groups such as the "content of vinyl groups" can be measured by methods well known in the art, and can be calculated through structural analyses such as H-NMR, C-NMR, and Si-NMR.

[0016] Addition-curable siloxane composition The addition-curable siloxane composition according to the present invention comprises a first organopolysiloxane and a second organopolysiloxane which contain aryl groups and have different refractive indices, a third organopolysiloxane which does not contain aryl groups and contains alkenyl groups directly bonded to silicon, an organohydrogenpolysiloxane which contains hydrogen groups (SiH) directly bonded to silicon, and silica.

[0017] The siloxane composition of the present invention contains three different organopolysiloxanes and has a minimal aryl group content and a low modulus, thereby exhibiting excellent reliability and adhesive properties.

[0018] The first organopolysiloxane and the second organopolysiloxane each independently adjust the content of aryl groups, which can increase the refractive index of the cured product through π-π interactions between aromatic rings, and alkyl groups, which have a low refractive index, to adjust the refractive index at a wavelength of 589 nm, thereby improving the light efficiency of the cured product. Furthermore, the first organopolysiloxane has a high content of T units, which increases the hardness of the cured product. However, this can lead to cracking in the cured product. Therefore, by adding a second organopolysiloxane, the modulus of the cured product can be adjusted to prevent cracking and to adjust the hardness and cracking of the cured product. Furthermore, since the first organopolysiloxane and the second organopolysiloxane alone can cause the cured product to discolor at high temperatures or crack due to insufficient modulus, the cured product can be improved in crack resistance and discoloration resistance by adding a third organopolysiloxane. Therefore, the siloxane composition of the present invention contains three different organopolysiloxanes, which improves the light efficiency of the cured product by adjusting the refractive index, and effectively improves the excellent heat resistance of the cured product, making it possible to produce a cured product with high hardness without the problem of discoloration at high temperatures. Therefore, the siloxane composition can produce a cured product with excellent reliability in mechanical, optical, and thermal properties.

[0019] First organopolysiloxane The first organopolysiloxane has a high content of T units and therefore plays a role in realizing high hardness upon curing.

[0020] The first organopolysiloxane includes an aryl group and has a refractive index of 1.48 to 1.50 at a wavelength of 589 nm. For example, the first organopolysiloxane may be represented by the following Chemical Formula 1. That is, the first organopolysiloxane may include M units, T units, and Q units.

[0021] [Chemical formula 1] [R 1 R 2 R 3 SiO 1 / 2 ] a[R 4 SiO 3 / 2 ] b [R 5 SiO 3 / 2 ] c [SiO 4 / 2 ] d In chemical formula 1, R 1 From R 3 are each independently a substituted or unsubstituted C 1-10 Alkyl group, C 2-10 Alkenyl group, or C 1-10 is an alkoxy group, R 4 and R 5 are each independently a substituted or unsubstituted C 1-10 Alkyl group, C 1-10 Alkoxy group, or C 6-12 are aryl groups, at least one of which is an aryl group; a is greater than 0 and less than 1, b is greater than or equal to 0 and less than 1, c+d is greater than 0 and less than 1, a+b+c+d is 1.

[0022] R 1 From R 3 may be the same or different, for example, substituted or unsubstituted C 1-5 Alkyl group or C 2-5 Alkenyl groups, specifically substituted or unsubstituted C 1-3 Alkyl group or C 2-4 It may be an alkenyl group.

[0023] In addition, the R 4 and R 5 are different and can be substituted or unsubstituted C 1-5 Alkyl group, C 1-5 Alkoxy group or C 6-10 At least one of the R 4 and R 5 are different and can be substituted or unsubstituted C 1-3Alkyl group, C 1-4 Alkoxy group or C 6-8 They may be aryl groups, and at least one may be an aryl group.

[0024] In this case, the alkyl group and alkenyl group may be linear or branched.

[0025] Specifically, the first organopolysiloxane may be represented by the following Chemical Formula 4. That is, the first organopolysiloxane may include M units and T units.

[0026] [Chemical formula 4] [R 1 3SiO 1 / 2 ] x [R 2 3SiO 1 / 2 ] y [R 4 SiO 3 / 2 ] b [R 5 SiO 3 / 2 ] c In chemical formula 4, R 1 is a substituted or unsubstituted C 1-10 Alkyl groups, specifically C 1-5 an alkyl group, more specifically a methyl group, an ethyl group, or a propyl group; R 2 is a substituted or unsubstituted C 2-10 Alkenyl groups, specifically C 2-5 an alkenyl group, more specifically a vinyl group or an allyl group; R 4 is a substituted or unsubstituted C 1-10 Alkyl groups, specifically C 1-5 an alkyl group, more specifically a methyl group, an ethyl group, or a propyl group; R 5 is a substituted or unsubstituted C 6-12 Aryl groups, specifically C 6-10 an aryl group, more specifically a phenyl group or a tolyl group; x+y+b+c is 1, x+y is between 0.1 and 0.5, or between 0.2 and 0.4, b+c may be from 0.5 to 0.9, or from 0.6 to 0.8.

[0027] The first organopolysiloxane may contain 10 to 33 mol % or 13 to 30 mol % of aryl groups relative to the total moles of all organic groups. If the aryl group content of the first organopolysiloxane is less than this range, the refractive index of the cured product may be low, resulting in low optical efficiency. If it exceeds this range, the product may easily discolor at high temperatures. In this case, the aryl group content may be the phenyl group content.

[0028] Additionally, the first organopolysiloxane may contain 5 to 20 mol % or 10 to 15 mol % of alkenyl groups relative to the total number of moles of all organic groups. If the alkenyl group content of the first organopolysiloxane is below this range, the crosslink density may be low, and the cured product may not achieve the desired hardness. If the alkenyl group content is above this range, the T unit content may be low, making it difficult to achieve high hardness in the cured product and causing discoloration at high temperatures. In this case, the alkenyl group content may be the vinyl group content.

[0029] The composition may contain the first organopolysiloxane and the second organopolysiloxane in a weight ratio of 1:0.3 to 1:5.0, a weight ratio of 1:1.0 to 1:3.0, or a weight ratio of 1:1.3 to 1:2.5. If the weight ratio of the first organopolysiloxane to the second organopolysiloxane is below this range, i.e., if the amount of the second organopolysiloxane is small relative to the weight of the first organopolysiloxane, the cured product may not reach the target hardness. If the weight ratio exceeds this range, i.e., if the amount of the second organopolysiloxane is excessive relative to the weight of the first organopolysiloxane, cracks may easily occur in the cured product.

[0030] Second organopolysiloxane The second organopolysiloxane serves to lower the modulus of the cured product, thereby preventing it from cracking easily.

[0031] The second organopolysiloxane includes an aryl group and has a refractive index of 1.43 to 1.47 at a wavelength of 589 nm. For example, the second organopolysiloxane may be represented by the following Chemical Formula 2. That is, the second organopolysiloxane may include M units, D units, T units, and Q units.

[0032] [Chemical formula 2] [R 6 R 7 R 8 SiO 1 / 2 ] e [R 9 R 10 SiO 2 / 2 ] f [R 11 SiO 3 / 2 ] g [SiO 4 / 2 ] h In the above Chemical Formula 2, R 6 From R 8 are each independently a substituted or unsubstituted C 1-10 Alkyl group, C 2-10 Alkenyl group, or C 1-10 is an alkoxy group, R 9 From R 11 are each independently a substituted or unsubstituted C 1-10 Alkyl group, C 1-10 Alkoxy group, or C 6-12 are aryl groups, at least one of which is an aryl group; e is greater than 0 and less than 1, f is greater than or equal to 0 and less than 1, g+h is greater than 0 and less than 1, e+f+g+h is 1.

[0033] R 6 From R8 may be the same or different, for example, substituted or unsubstituted C 1-5 Alkyl group or C 2-5 Alkenyl groups, specifically substituted or unsubstituted C 1-3 Alkyl group or C 2-4 It may be an alkenyl group.

[0034] In addition, the R 9 and R 10 are identical or different, substituted or unsubstituted C 1-5 Specifically, the R 9 and R 10 are identical, and substituted or unsubstituted C 1-3 It may be an alkyl group, more specifically a methyl group, an ethyl group or a propyl group.

[0035] R 11 is a substituted or unsubstituted C 6-12 Specifically, the R 11 is a substituted or unsubstituted C 6-10 Aryl group or C 6-8 It may be an aryl group.

[0036] In this case, the alkyl group and alkenyl group may be linear or branched.

[0037] Specifically, the second organopolysiloxane may be represented by the following Chemical Formula 5. That is, the second organopolysiloxane may include M units, D units, and T units.

[0038] [Chemical formula 5] [R 6 3SiO 1 / 2 ] m [R 7 3SiO 1 / 2 ] n [R 9 2SiO 2 / 2 ] f [R 11 SiO 3 / 2 ] g In chemical formula 5, R 6 is a substituted or unsubstituted C 1-10 Alkyl groups, specifically C 1-5 an alkyl group, more specifically a methyl group, an ethyl group, or a propyl group; R 7 is a substituted or unsubstituted C 2-10 Alkenyl groups, specifically C 2-5 an alkenyl group, more specifically a vinyl group or an allyl group; R 9 is a substituted or unsubstituted C 1-10 Alkyl groups, specifically C 1-5 an alkyl group, more specifically a methyl group, an ethyl group, or a propyl group; R 11 is a substituted or unsubstituted C 6-12 Aryl groups, specifically C 6-10 an aryl group, more specifically a phenyl group or a tolyl group; m+n+f+g is 1, m+n is from 0.2 to 0.5, or from 0.30 to 0.45; f+g is between 0.5 and 0.8, or between 0.55 and 0.70.

[0039] The second organopolysiloxane may contain aryl groups in an amount of 1 to 30 mol %, or 5 to 20 mol %, based on the total moles of all organic groups. If the aryl group content of the second organopolysiloxane is less than this range, the refractive index of the cured product may be low, resulting in low light efficiency. If the aryl group content is greater than this range, the cured product may easily discolor at high temperatures. In this case, the aryl group content may be the phenyl group content.

[0040] The second organopolysiloxane may contain 0.1 to 10 mol %, or 0.5 to 5 mol %, of alkenyl groups relative to the total number of moles of all organic groups. If the alkenyl group content of the second organopolysiloxane is less than this range, the cured product may have a low crosslink density and very low hardness, while if it exceeds this range, the cured product may have a high modulus and be prone to cracking. In this case, the alkenyl group content may be the vinyl group content.

[0041] The second organopolysiloxane may have a viscosity of 0.1 to 10 Pa·s, or 0.5 to 5 Pa·s, at 25° C. If the viscosity of the second organopolysiloxane at 25° C. is below this range, the cured product may become brittle, whereas if it exceeds this range, the fluidity may decrease, resulting in insufficient workability of the siloxane composition.

[0042] Third organopolysiloxane The third organopolysiloxane serves to improve the crack resistance and discoloration resistance of the cured product.

[0043] The third organopolysiloxane does not contain an aryl group but contains an alkenyl group directly bonded to silicon. For example, the third organopolysiloxane may be represented by the following Chemical Formula 3. That is, the third organopolysiloxane may contain M units, D units, and Q units.

[0044] [Chemical formula 3] [R 15 R 16 R 17 SiO 1 / 2 ] i [R 18 R 19 SiO 2 / 2 ] j [SiO 4 / 2 ] k In the above Chemical Formula 3, R 15 From R 19 are each independently a substituted or unsubstituted C1-10 Alkyl group, C 2-10 Alkenyl group, or C 1-10 one is an alkoxy group and at least one is an alkenyl group; i is greater than 0 and less than 1, j is greater than or equal to 0 and less than 1, k is greater than 0.2 and less than 1, i+j+k is 1.

[0045] R 15 From R 19 may be the same or different, for example, substituted or unsubstituted C 1-5 Alkyl group or C 2-5 Alkenyl groups, specifically substituted or unsubstituted C 1-3 Alkyl group or C 2-4 It may be an alkenyl group.

[0046] In this case, the alkyl group and alkenyl group may be linear or branched.

[0047] Specifically, the third organopolysiloxane may be represented by the following Chemical Formula 6. That is, the third organopolysiloxane may include M units and Q units.

[0048] [Chemical formula 6] [R 15 3SiO 1 / 2 ] o [R 16 3SiO 1 / 2 ] p [SiO 4 / 2 ] k In chemical formula 6, R 15 is a substituted or unsubstituted C 1-10 Alkyl groups, specifically C 1-5 an alkyl group, more specifically a methyl group, an ethyl group, or a propyl group; R 16 is a substituted or unsubstituted C 2-10 Alkenyl groups, specifically C 2-5an alkenyl group, more specifically a vinyl group or an allyl group; o+p+k is 1, o+p is between 0.2 and 0.7, or between 0.4 and 0.6; k is between 0.3 and 0.8, or between 0.4 and 0.6.

[0049] The third organopolysiloxane may contain 0.1 to 20 mol %, or 7 to 15 mol %, of alkenyl groups relative to the total number of moles of all organic groups. If the alkenyl group content of the third organopolysiloxane is less than this range, the cured product may have a low crosslink density and very low hardness, while if it exceeds this range, the cured product may have a high modulus and be prone to cracking. In this case, the alkenyl group content may be the vinyl group content.

[0050] The third organopolysiloxane may be included in the composition in an amount of 5 to 60 parts by weight, 10 to 50 parts by weight, or 30 to 50 parts by weight, based on 100 parts by weight of the total amount of the first organopolysiloxane and the second organopolysiloxane. If the content of the third organopolysiloxane is less than this range, the cured product may have poor crack resistance or poor discoloration resistance, while if the content is greater than this range, the cured product may not achieve the desired hardness.

[0051] Organohydrogenpolysiloxane The organohydrogenpolysiloxane serves to cure the siloxane composition.

[0052] The organohydrogenpolysiloxane contains at least one hydrogen group (SiH) directly bonded to silicon in each molecule. For example, the organohydrogenpolysiloxane may be represented by the following chemical formula 7.

[0053] [Chemical formula 7] [R 20 R 21 R 22SiO 1 / 2 ] q [R 23 R 24 SiO 2 / 2 ] r [R 25 SiO 3 / 2 ] s [SiO 4 / 2 ] t In chemical formula 7, R 20 From R 22 are each independently a hydrogen group, a substituted or unsubstituted C 1-10 Alkyl group, C 2-10 Alkenyl group, or C 1-10 alkoxy groups, at least one of which is a hydrogen group; R 23 From R 25 are each independently a substituted or unsubstituted C 1-10 Alkyl group, C 2-10 Alkenyl group or C 6-12 is an aryl group, q is greater than 0 and less than 1, r+t is greater than or equal to 0 and less than 1, s is greater than 0 and less than 1, q+r+s+t is 1.

[0054] Specifically, the R 20 From R 22 may be the same or different, and may be, for example, a hydrogen group, a substituted or unsubstituted C 1-5 Alkyl group, or C 2-5 alkenyl groups, at least one of which is a hydrogen group, specifically a hydrogen group or a substituted or unsubstituted C 1-3 They are alkyl groups, at least one of which may be a hydrogen group.

[0055] In addition, the R 23 From R 25 are identical or different, substituted or unsubstituted C 6-10 Aryl groups, specifically substituted or unsubstituted C 6-8It may be an aryl group, more specifically a phenyl group or a tolyl group.

[0056] In this case, the alkyl group and alkenyl group may be linear or branched.

[0057] The organohydrogenpolysiloxane may have a refractive index at a wavelength of 589 nm of 1.43 to 1.50, or 1.43 to 1.47.

[0058] The organohydrogenpolysiloxane may have a viscosity at 25°C of 0.1 to 50 mPa·s, or 1 to 30 mPa·s. If the organohydrogenpolysiloxane has a viscosity at 25°C below this range, its high volatility may cause problems such as changes in the composition ratio during storage or problems such as evaporation of the low molecular weight organohydrogenpolysiloxane during curing. If the viscosity exceeds this range, the reaction rate during molding of the cured product may be slow, requiring a long curing time, which may hinder workability when producing molded products using the curable organopolysiloxane composition.

[0059] The organohydrogenpolysiloxane may contain aryl groups in an amount of 5 to 30 mol%, or 10 to 20 mol%, based on the total moles of all organic groups. If the aryl group content of the organohydrogenpolysiloxane is less than this range, the cured product may have low photoefficiency, while if it exceeds this range, the cured product may discolor due to yellowing at high temperatures. In this case, the aryl group content may be the phenyl group content.

[0060] In addition, the total number of moles of hydrogen groups (SiH) directly bonded to silicon in the organohydrogenpolysiloxane may be 0.3 to 3.5 times, 0.5 to 3.0 times, or 0.6 to 1.5 times the total number of moles of alkenyl groups in the first, second, third, and third organopolysiloxanes. If the total number of moles of SiH is less than this range relative to the number of moles of alkenyl groups, it may be difficult to ensure sufficient crosslink density, resulting in uncured products or reduced mechanical properties. If the total number of moles of SiH is greater than this range, the excess hydrogen groups may cause a dehydrogenation reaction, resulting in a spongy cured product.

[0061] silica Silica plays a role in imparting thixotropy to the siloxane composition so that it can maintain a dome shape independently even when dispensed onto a printed circuit board (PCB) that has no walls or dams.

[0062] Examples of the silica include fumed silica, precipitated silica, silica gel, quartz powder, fused silica, etc. Specifically, the silica may include fumed silica or precipitated silica.

[0063] In addition, the average particle size of the silica may be 20 μm or less, 10 μm or less, or 7 μm or less. If the average particle size of the silica exceeds the above range, it may be difficult to improve the strength of the cured product.

[0064] The silica has a BET specific surface area of ​​100 m 2 / g or more, 100 to 400m 2 / g, or 100 to 300m 2 When the BET specific surface area of ​​the silica is within this range, the mechanical properties such as hardness and tensile strength of the produced cured product can be effectively improved.

[0065] The silica may have a hydrophilic surface that has been hydrophobized. Using silica with a hydrophobized surface can improve the shelf life of the siloxane composition. Examples of substances that can be used for the hydrophobization include 1,1,1,3,3,3-hexamethyldisilazane, divinyltetramethyldisilazane, 1,1,3,3-tetramethyldisilazane, and cyclosiloxane.

[0066] The silica may be included in the composition in an amount of 2 to 15 parts by weight, 3 to 10 parts by weight, or 4 to 9 parts by weight, per 100 parts by weight of the total of the first to third organopolysiloxanes and the organohydrogenpolysiloxane. If the silica content is below this range, the thixotropy of the siloxane composition is too low, making it difficult to maintain a dome shape independently. If the silica content exceeds this range, the thixotropy of the siloxane composition is too high, making dispensing difficult and causing problems in use. Also, domes with a high aspect ratio may be formed, making it difficult to form domes with appropriate light diffusion.

[0067] The siloxane composition may contain the second organopolysiloxane and silica in a weight ratio of 1:0.1 to 1:0.4, a weight ratio of 1:0.1 to 1:0.25, or a weight ratio of 1:0.1 to 1:0.2. If the weight ratio of silica to the second organopolysiloxane is below this range, i.e., if a small amount of silica is included, the thixotropy of the composition may be too low to form a dome shape in the cured product. If the weight ratio is above this range, i.e., if an excessive amount of silica is included, the transmittance of the cured product may be low, resulting in low light efficiency.

[0068] The siloxane composition may contain additives such as nonionic surfactants, catalysts, cure retarders, and adhesion promoters.

[0069] Nonionic surfactants The nonionic surfactant plays a role in improving the thixotropy of the siloxane composition when used in conjunction with a filler such as silica.

[0070] Furthermore, the nonionic surfactant can generally be any surfactant that can be added to a siloxane composition without any particular limitations, and an example thereof is polypropylene glycol.

[0071] The nonionic surfactant may be included in the composition in an amount of 0.1 to 8.0 parts by weight, 0.5 to 5.0 parts by weight, or 0.5 to 3.0 parts by weight, based on 100 parts by weight of the total amount of the first organopolysiloxane and the second organopolysiloxane. If the content of the nonionic surfactant is less than this range, the cured product may not achieve the desired thixotropy, resulting in an inability to achieve a dome shape. If the content of the nonionic surfactant is greater than this range, the transmittance of the cured product may be low, resulting in poor light efficiency.

[0072] catalyst The catalyst is an addition cure catalyst and serves to accelerate the addition cure reaction (hydrosilylation reaction) within the siloxane composition.

[0073] The catalyst is not particularly limited as long as it is a catalyst that is generally used as a catalyst for addition curing reactions. For example, platinum-based catalysts, rhodium-based catalysts, and palladium-based catalysts can be used.

[0074] Examples of the platinum catalyst include platinum fine powder, platinum black, chloroplatinic acid, alcohol-modified chloroplatinic acid, chloroplatinic acid / diolefin complex, platinum / olefin complex, platinum-carbonyl complex, chloroplatinic acid / alkenylsiloxane complex, platinum / alkenylsiloxane complex, and chloroplatinic acid / acetylene alcohol complex. In terms of addition curing reaction (hydrosilylation reaction) performance, the catalyst may be a platinum / alkenylsiloxane complex. The complex may be dissolved in an organic solvent such as xylene and included in the composition.

[0075] Examples of the platinum-carbonyl complexes include platinum bis(acetoacetate) and platinum bis(acetylacetonate), and examples of the chloroplatinic acid / alkenylsiloxane complexes include a chloroplatinic acid / divinyltetramethyldisiloxane complex and a chloroplatinic acid / tetravinyltetramethylcyclotetrasiloxane complex. Examples of the platinum / alkenylsiloxane complexes include a platinum / divinyltetramethyldisiloxane complex and a platinum / tetravinyltetramethylcyclotetrasiloxane complex.

[0076] Examples of the alkenylsiloxane of the complex include 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 1,3-divinyl-1,1,3,3-tetraethyldisiloxane, 1,3-divinyl-1,1,3,3-tetraphenyldisiloxane, 1,3-diallyl-1,1,3,3-tetramethyldisiloxane, 1,3-dihexenyl-1,1,3,3-tetramethyldisiloxane, 1,3,5,7-tetramethyl-1,3,5,7- Examples of suitable alkenylsiloxanes include tetravinylcyclotetrasiloxane, 1,3,5,7-tetraethyl-1,3,5,7-tetravinylcyclotetrasiloxane, 1,3,5,7-tetraphenyl-1,3,5,7-tetravinylcyclotetrasiloxane, 1,3,5,7-tetramethyl-1,3,5,7-tetraallylcyclotetrasiloxane, and 1,3,5,7-tetramethyl-1,3,5,7-tetrahexenylcyclotetrasiloxane. In terms of producing a platinum / alkenylsiloxane complex with excellent stability, the alkenylsiloxane may be 1,3-divinyl-1,1,3,3-tetramethyldisiloxane.

[0077] The catalyst is added in an amount that promotes the curing of the siloxane composition, but the amount is not particularly limited. For example, the catalyst may be added in an amount of 0.5 to 50 ppm or 1 to 20 ppm based on the platinum content relative to the total weight of the siloxane composition. If the catalyst content is less than this range, the curing rate of the siloxane composition may be significantly reduced, resulting in reduced productivity. If the catalyst content is greater than this range, it may be difficult to ensure the pot life of the siloxane composition, and the cured product may yellow during heat curing, resulting in reduced optical performance.

[0078] Set retarder The cure retarder serves to control the cure rate of the siloxane composition.

[0079] Furthermore, the cure retarder can generally be any one that can be added to a siloxane composition without any particular limitation, and examples thereof include 2-methyl-3-butan-2-ol, 1-ethynyl-2-cyclohexanol, 2-phenyl-3-butan-2-ol, divinyltetramethyldisiloxane, and cyclovinylsiloxane.

[0080] The cure retarder may be included in an amount of 1 part by weight or less, or 0.0001 to 1 part by weight, per 100 parts by weight of the siloxane composition. If the cure retarder content exceeds this range, the hardness of the cured product may be low, or the curing rate of the siloxane composition may be slow or the composition may not cure at all.

[0081] Adhesion promoter The adhesion promoter serves to improve the adhesive strength of a cured product prepared from the siloxane composition to a substrate that comes into contact with the cured product.

[0082] The adhesion promoter can be any suitable additive to a siloxane composition, and may be, for example, an organosilicon compound. Examples of the adhesion promoter include organosilanes containing trialkoxysiloxy groups such as trimethoxysiloxy and triethoxysiloxy, or trialkoxysilylalkyl groups such as trimethoxysilylethyl and triethoxysilylethyl; or organosiloxane oligomers containing one of the following functional groups: hydrosilyl, silicon-bonded alkenyl, silicon-bonded methacryloxyalkyl, and silicon-bonded epoxy-functional alkyl groups. Examples of the epoxy-functional alkyl groups include 3-glycidoxypropyl, 4-glycidoxybutyl, 2-(3,4-epoxycyclohexyl)ethyl, and 3-(3,4-epoxycyclohexyl)propyl. The adhesion promoter may also include, for example, epoxy-functional ethyl polysilicate; and reaction products of aminoalkyltrialkoxysilanes and epoxy-functional alkyltrialkoxysilanes.

[0083] Specifically, the adhesion promoter may include vinyltrimethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, hydrogentriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-ethoxycyclohexyl)ethyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, a reaction product of 3-glycidoxypropyltriethoxysilane and 3-aminopropyltriethoxysilane, a condensation reaction product of a silanol-endblocked methylvinylsiloxane oligomer and 3-glycidoxypropyltrimethoxysilane, a condensation reaction product of a silanol-endblocked methylvinylsiloxane oligomer and 3-methacryloxypropyltriethoxysilane, or tris(3-trimethoxysilylpropyl)isocyanurate.

[0084] The adhesion promoter may be present in an amount of up to 3 parts by weight, or from 0.01 to 3 parts by weight, based on 100 parts by weight of the siloxane composition.

[0085] additives The addition-curable siloxane composition may further contain additives commonly used in the art, such as inorganic fillers, silicone rubber powder, resin powder, heat resistance agents, antioxidants, radical scavengers, light stabilizers, dyes, pigments, and flame-retardant additives.

[0086] The addition-curable siloxane composition according to the present invention may have a viscosity at 25° C. of 10 to 50 Pa·s or 10 to 30 Pa·s. The siloxane composition may also have a thixotropic index at 25° C. of 2.0 to 4.0 or 2.1 to 3.9. In this case, the thixotropic index is the value of [viscosity at 25° C. at a shear rate of 1 / s] / [viscosity at 25° C. at a shear rate of 10 / s].

[0087] Furthermore, a cured product having an average thickness of 6 mm produced from the addition-curable siloxane composition may have a hardness of 20 to 40 Shore D, or 22 to 37 Shore D.

[0088] A cured product having an average thickness of 2 mm produced from the addition-curable silicone composition may have a transmittance of 85% or more, or 85 to 95%, for light with a wavelength of 450 nm.

[0089] The addition-curable siloxane composition according to the present invention has an appropriate viscosity, resulting in excellent fluidity, and excellent thixotropy, resulting in excellent transparency of the cured film, making it highly suitable as an encapsulant for self-dome-shaped light-emitting diodes even on flat substrates without walls or dams. Furthermore, the addition-curable siloxane composition also produces cured films with excellent hardness and adhesive strength, making it applicable in a variety of fields, including LED element encapsulants, adhesives, coatings, potting agents, and sealants.

[0090] Electronic / Electrical Equipment In addition, the electronic / electrical device according to the present invention includes a cured product produced by curing the addition-curable siloxane composition.

[0091] In this case, the electronic / electrical device may be a light emitting diode (LED).

[0092] MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below through examples. However, these examples are merely intended to aid in understanding the present invention and are not intended to limit the scope of the present invention in any way.

[0093] Experimental Example 1: Preparation of addition-curable siloxane composition 20.9g of the first organopolysiloxane-2, 36.8g of the second organopolysiloxane-1, 7.4g of organohydrogenpolysiloxane, 27.0g of the third organopolysiloxane, 6.5g of silica, and 0.49g of cure retarder were added to a reaction vessel and stirred for 10 minutes with a hand mixer. Then, 0.5g of a nonionic surfactant, 0.4g of an adhesion promoter, and 0.01g of a catalyst were added and stirred for 10 minutes with a hand mixer. After that, air bubbles were removed in a desiccator under a vacuum of 20 torr or less, and a colorless, transparent addition-curable siloxane composition was obtained.

[0094] Experimental Examples 2 to 21: Preparation of addition-curable siloxane compositions Addition-curable siloxane compositions were prepared using the components in the compositions shown in Tables 1 to 3. In this case, the "number of moles of vinyl groups in the organopolysiloxane" refers to the total number of moles of vinyl groups in the first organopolysiloxane, the second organopolysiloxane, and the third organopolysiloxane.

[0095] [Table 1]

[0096] [Table 2]

[0097] [Table 3]

[0098] [Table 4(1)] [Table 4(2)] Test example: Evaluation of characteristics The physical properties of the addition-curable siloxane compositions of the experimental examples and the cured products prepared therefrom were measured by the following methods, and the results are shown in Table 5.

[0099] Specifically, the cured products were prepared by curing the addition-curable silicone compositions of the experimental examples at 190° C. for 10 minutes using a mold capable of molding the compositions to an average thickness of 2 mm or 6 mm.

[0100] (1) Viscosity and thixotropy index The viscosity of the addition-curable siloxane compositions of the experimental examples was measured at 25°C at a shear rate of 10 / s using a rheometer (Rheometer, MCR302, Anton Paar), and the thixotropic index was calculated as (viscosity at a shear rate of 1 / s) / (viscosity at a shear rate of 10 / s).

[0101] (2)Hardness The hardness was measured at 25°C on a cured product with an average thickness of 6 mm using a Shore D hardness tester (ASKER TYPE D manufactured by KOBUNSHI KEIKI Co., Ltd.).

[0102] (3) Transmittance The transmittance of a cured product having an average thickness of 2 mm to light with a wavelength of 450 nm was measured using a spectrophotometer (Hitachi U-3900H).

[0103] (4) Adhesive strength An addition-curable siloxane composition was applied between two aluminum substrates and cured at 150°C for 30 minutes to a size of 10 mm across, 5 mm wide, and 1 mm high. The two aluminum substrates were then pulled together using UTM equipment to measure the maximum stress at which the silicone broke from the aluminum substrates.

[0104] [Table 5] As shown in Table 5, the addition-curable siloxane compositions of Experimental Examples 1 to 10 had appropriate viscosities and thixotropic indices at 25°C, and the cured products produced from these compositions had excellent hardness, transmittance, and adhesive strength, making them highly suitable as encapsulants for self-dome shaped LEDs even on flat substrates without walls or dams.

[0105] On the other hand, Experimental Example 11, which contained organopolysiloxane-1 with a high refractive index of 1.52 at a wavelength of 589 nm and an excessive content of phenyl groups, and Experimental Example 21, which contained an excessive amount of nonionic surfactant, had low transmittance for light with a wavelength of 450 nm and were therefore unsuitable as encapsulants for LED elements.

[0106] Furthermore, Experimental Examples 12 and 13, which contained organopolysiloxane-2 with a low refractive index of 1.42 at a wavelength of 589 nm or organopolysiloxane-3 with a low refractive index of 1.41 at a wavelength of 589 nm, had low transmittance for light with a wavelength of 450 nm and insufficient adhesive strength. In particular, Experimental Example 13, which contained organopolysiloxane-3 without a phenyl group, also produced a cured product with very poor hardness.

[0107] Experimental Example 14, which contained a small amount of the third organopolysiloxane, and Experimental Example 16, which contained a small amount of the organohydrogenpolysiloxane, produced cured products with very poor adhesive strength. In particular, Experimental Example 16, which contained a small amount of the second organopolysiloxane relative to the weight of the first organopolysiloxane, produced cured products with very poor hardness.

[0108] Furthermore, the composition of Experimental Example 15, which contained an excessive amount of the third organopolysiloxane, had an excessively high viscosity at 25°C and a very low thixotropy index, and therefore had very poor workability.

[0109] In Experimental Example 17, which contained an excess amount of organohydrogenpolysiloxane and an excess amount of the second organopolysiloxane relative to the weight of the first organopolysiloxane, the adhesive strength of the cured product was insufficient.

[0110] Furthermore, Experimental Example 18, which contained a small amount of silica, and Experimental Example 20, which contained a small amount of a nonionic surfactant, had a low thixotropy index, and therefore workability was insufficient.

[0111] Experimental Example 19 contained an excessive amount of silica, resulting in an insufficient transmittance of the cured product to light with a wavelength of 450 nm, and contained an excessive amount of silica relative to the weight of the second organopolysiloxane, resulting in an excessively high thixotropic index of the composition.

Claims

1. a first organopolysiloxane containing an aryl group and having a refractive index at a wavelength of 589 nm of 1.48 to 1.50; a second organopolysiloxane containing an aryl group and having a refractive index at a wavelength of 589 nm of 1.43 to 1.47; a third organopolysiloxane that does not contain aryl groups and contains alkenyl groups bonded directly to silicon; an organohydrogenpolysiloxane containing hydrogen groups directly bonded to silicon and having a refractive index at a wavelength of 589 nm of 1.43 to 1.50; silica; and a nonionic surfactant, the weight ratio of the first organopolysiloxane to the second organopolysiloxane (first organopolysiloxane:second organopolysiloxane) is 1:1.0 to 1:3.0; the third organopolysiloxane is contained in an amount of 5 to 60 parts by weight per 100 parts by weight of the total amount of the first organopolysiloxane and the second organopolysiloxane; the total number of moles of hydrogen groups (SiH) directly bonded to silicon in the organohydrogenpolysiloxane is 0.3 to 3.5 times the total number of moles of alkenyl groups contained in the first organopolysiloxane, the second organopolysiloxane, and the third organopolysiloxane; the silica is contained in an amount of 2 to 15 parts by weight per 100 parts by weight of the total of the first organopolysiloxane, the second organopolysiloxane, the third organopolysiloxane, and the organohydrogenpolysiloxane; The addition-curable siloxane composition contains 0.1 to 8.0 parts by weight of the nonionic surfactant per 100 parts by weight of the total amount of the first organopolysiloxane and the second organopolysiloxane.

2. The addition-curable siloxane composition according to claim 1 , wherein the first organopolysiloxane is represented by the following chemical formula 1: [Chemical formula 1] [R １ R ２ R ３ SiO １／２ ] ａ [R ４ SiO ３／２ ] ｂ [R ５ SiO ３／２ ] ｃ [SiO ４／２ ] ｄ In chemical formula 1, R １ From R ３ are each independently substituted or unsubstituted C １－１０ Alkyl group, C ２－１０ alkenyl group, or C １－１０ is an alkoxy group, R ４ and R ５ are each independently substituted or unsubstituted C １－１０ Alkyl group, C １－１０ an alkoxy group, or C ６－１２ are aryl groups, at least one of which is an aryl group; a is greater than 0 and less than 1; b is equal to or greater than 0 and less than 1; c+d is greater than 0 and less than 1, a+b+c+d is 1.

3. The addition-curable siloxane composition according to claim 1 , wherein the second organopolysiloxane is represented by the following chemical formula 2: [Chemical formula 2] [R ６ R ７ R ８ SiO １／２ ] ｅ [R ９ R １０ SiO ２／２ ] ｆ [R １１ SiO ３／２ ] ｇ [SiO ４／２ ] ｈ In the above Chemical Formula 2, R ６ From R ８ are each independently substituted or unsubstituted C １－１０ Alkyl group, C ２－１０ alkenyl group, or C １－１０ is an alkoxy group, R ９ From R １１ are each independently substituted or unsubstituted C １－１０ Alkyl group, C １－１０ an alkoxy group, or C ６－１２ are aryl groups, at least one of which is an aryl group; e is greater than 0 and less than 1; f is greater than or equal to 0 and less than 1; g+h is greater than 0 and less than 1, e+f+g+h is 1.

4. The addition-curable siloxane composition according to claim 1 , wherein the third organopolysiloxane is represented by the following chemical formula 3: [Chemical formula 3] [R １５ R １６ R １７ SiO １／２ ] ｉ [R １８ R １９ SiO ２／２ ] ｊ [SiO ４／２ ] ｋ In the above Chemical Formula 3, R １５ From R １９ are each independently substituted or unsubstituted C １－１０ Alkyl group, C ２－１０ alkenyl group, or C １－１０ at least one is an alkoxy group and at least one is an alkenyl group; i is greater than 0 and less than 1; j is greater than or equal to 0 and less than 1; k is greater than 0.2 and less than 1; i+j+k is 1.

5. The addition-curable siloxane composition described in claim 1, wherein the nonionic surfactant is contained in an amount of 0.5 to 5.0 parts by weight per 100 parts by weight of the total amount of the first organopolysiloxane and the second organopolysiloxane.

6. The addition-curable siloxane composition of claim 1, comprising the first organopolysiloxane and the second organopolysiloxane in a weight ratio of 1:1.3 to 1:2.

5.

7. An electronic / electrical device comprising a cured product produced by curing the addition-curable siloxane composition according to any one of claims 1 to 6.

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