JP5574906B2 - Silicone-containing encapsulant - Google Patents

Description

  The present invention relates to a sealing material composition, and more specifically, to a sealing material composition that can be used for a solid-state light emitting device.

  In recent years, light emitting diodes (LEDs) have been widely used in many electronic devices such as LCD backlight sources, large display devices, and light illumination equipment. Therefore, the demand for LEDs having high brightness is increasing. Due to the environmental requirements of various LED applications, encapsulant compositions suitable for use in light emitting devices are uniform, have high transparency, and long-term storage because they resist high temperatures when high currents are applied It should have some characteristics, such as being capable of capacity. Conventional transparent encapsulant materials used in LEDs include epoxies or silicone resins, which have better optical properties but are expensive. On the other hand, epoxy resins have been widely used because of their low cost. However, the epoxy resin has a serious problem that yellowing occurs when it is used as an LED encapsulant composition. The yellowing of the epoxy resin caused by the high temperature of the high output operation affects the transmittance of short wavelength light and may cause a color shift. Thus, epoxy resins are limited in their use in high current and high temperature operating environments.

  Prevention of yellowing of a sealing material composition such as an epoxy resin is usually achieved by adding an antioxidant. The added antioxidant can reduce the degradation rate of the polymer by removing the peroxide groups to stop the chain reaction or by breaking down the hydroperoxide produced during the degradation of the polymer. However, the yellowing prevention achieved by the addition of antioxidants is not satisfactory for long-term operation of the LED and not only is it difficult to find a suitable antioxidant, but some antioxidants are It has also been found to have high volatility, which can cause migration problems within the encapsulant material.

  In addition, internal stresses caused by high temperatures during high power operation can adversely affect semiconductor devices, cause short circuits, and reduce the brightness of applied LEDs. Therefore, four methods are disclosed in US Pat. No. 5,145,88 to reduce the internal stress of the encapsulant composition: (1) Decreasing the glass transition temperature (Tg) of the encapsulant composition (2) Decrease in linear expansion coefficient of the sealing material composition; (3) Decrease in Young's modulus of elasticity (E); and (4) Decrease in shrinkage (ε). In general, the mechanical strength of the encapsulant at high temperatures decreases due to the decrease in glass transition temperature (Tg); the decrease in elastic Young's modulus causes the adhesion of the encapsulant to the chip, circuit board or lead frame. In addition, if the filler is increased considerably, the viscosity of the encapsulant increases too much, which is not preferable for workability.

  US Pat. No. 6,800,373 discloses an encapsulant composition comprising a silicone resin, a low molecular weight alicyclic compound, an aromatic compound, a heterocyclic compound having an epoxy resin functional group, and a siloxane surfactant. . However, the light transmission is inadequate, and the siloxane surfactant does not participate in the reaction and does not form a uniform mixture with common epoxy encapsulant compositions.

  Accordingly, it is desirable to provide an improved encapsulant composition that can be used in solid state light emitting devices that achieve low internal stress and better anti-yellowing performance.

U.S. Pat.No. 5,145,88 U.S. Patent 6,800,373

  An object of the present invention is to provide an encapsulant composition for a solid-state light emitting device such as an LED, which overcomes the yellowing problem and achieves low internal stress under long-time high temperature operation conditions. is there.

  In order to achieve this object, the present invention provides (a) 30 to 60% by weight of an epoxy resin; (b) 30 to 60% by weight of an acid anhydride curing agent; (c) the above (a) and (b); 0.1-30 wt% carbinol siloxane resin capable of forming a homogeneous mixture; and (d) 0.1-5 wt% reactive UV absorber and / or reactive hindered amine light stabilizer (HALS) An encapsulant composition is provided.

The present invention also comprises (a) 30 to 60% by weight of an epoxy resin; (b) 30 to 60% by weight of an acid anhydride curing agent; 0.1 to 30% by weight of a carbinol siloxane resin obtained; (d) 0.01 to 3.0% by weight of a curing accelerator;
Another encapsulant composition comprising: (e) 0.1-5 wt% reactive UV absorber; and (f) 0.1-5 wt% reactive hindered amine light stabilizer (HALS): I will provide a. In addition, reactive antioxidants and phosphorus-containing flame retardants can be selectively used.

  In addition, the present invention forms (a) 30-60% by weight epoxy resin; (b) 30-60% by weight acid anhydride curing agent; (c) forming a homogeneous mixture with (a) and (b) above. 0.1-30 wt.% Carbinol siloxane resin; (d) 0.1-5 wt.% Common UV absorber; and (e) 0.1-5 wt.% Common hindered amine light. Also provided is a silicone-containing encapsulant composition comprising a stabilizer (HALS):

  Objects, technical features and advantages of the present invention are described in more detail below.

  The present invention provides a sealing material composition for a solid-state light emitting device such as an LED, which achieves low internal stress and can provide better yellowing prevention performance for a long time and at a high temperature operation. The present invention introduces a carbinol siloxane resin in the presence of an epoxy resin and an acid anhydride to reduce the hardness and internal stress during curing of the epoxy resin composition; in addition, by using the carbinol siloxane resin. , Preventing cracking of the sealant and overcoming the problem of low adhesion. Addition of a UV absorber having a reactive group and a hindered amine light stabilizer (HALS) can contribute to improvement of the yellowing prevention ability of the encapsulant.

  Addition of carbinol siloxane resin, after polymerization of epoxy resin and acid anhydride, reacts with remaining unreacted acid anhydride, if any, to reduce yellowing caused by unreacted acid anhydride It is possible. Further, the carbinol siloxane resin can react with the reactive group of the epoxy resin to increase the elasticity of the sealing material. Furthermore, any remaining unreacted carbinol siloxane resin can act as a filler and reduce the linear expansion coefficient of the encapsulant. In the present invention, the carbinol siloxane resin is a compound of the following formula:

Wherein (R ¹ O) _m is an alkylene oxide group (when m = 1) or a poly (alkylene oxide) group (when m>1); R ¹ is independently —C ₂ H ₄ It represents a linear or branched divalent group selected from —, —C ₃ H ₆ —, and —C ₄ H ₈ —. It should be noted that when m is greater than 1, for example when 2 or more, the alkylene oxide groups can be the same or different to form poly (alkylene oxide) homopolymers, random copolymers, and block copolymers. .

R ² and R ³ are independently H or C ₁ -C ₂ alkyl; R ⁴ is H or C ₁ -C ₂ alkyl and is the same as or different from R ² ; x is an integer from 1 to 100 Yes; y is an integer from 1 to 100; n is an integer from 1 to 5; and m is an integer from 1 to 40.

  Carbinol siloxane resins have the advantage of lower internal stress and linear expansion, but cannot solve all the yellowing problems, and therefore UV absorbers and / or hindered amine light stabilizers with reactive groups ( The addition of HALS) would be effective. By adjusting the amount of carbinol siloxane resin used, a reactive UV absorber containing OH or COOH reactive groups can react with the encapsulant to form a polymeric UV absorber. Therefore, the volatilization due to migration of low molecular weight UV absorbers can be reduced and thus enhance the long term performance of the UV absorbers. Since the yellowing prevention performance of this type of encapsulant is substantially improved, long-term requirements for LEDs can be satisfied.

  The sealing material composition of the present invention comprises: (a) 30 to 60% by weight of an epoxy resin; (b) 30 to 60% by weight of an acid anhydride curing agent; (c) uniform with (a) and (b) above. 0.1-30 wt% carbinol siloxane resin capable of forming a mixture; and (d) 0.1-5 wt% reactive UV absorber or reactive hindered amine light stabilizer (HALS). . The present invention also comprises (a) 30 to 60% by weight of an epoxy resin; (b) 30 to 60% by weight of an acid anhydride curing agent; (c) a uniform mixture with (a) and (b). 0.1 to 30% by weight of a carbinol siloxane resin obtained; (d) 0.01 to 3.0% by weight of a curing accelerator; (e) 0.1 to 5% by weight of a reactive UV absorber; and (F) 0.1 to 5% by weight of a reactive hindered amine light stabilizer (HALS): another encapsulant composition is also provided. In addition, reactive antioxidants and phosphorus-containing flame retardants can be selectively used.

  The encapsulant composition of the present invention comprises an epoxy resin and a curing agent as main components, a carbinol siloxane resin for reducing the internal stress of the encapsulant, and a UV absorber or a hindered amine light stabilizer having a reactive group ( In addition, reactive antioxidants and phosphorus-containing flame retardants can be selectively added to improve HAS) and to improve better anti-yellowing performance. In the sealing material composition of the present invention, (a) the epoxy resin may be an aromatic epoxy resin, an alicyclic epoxy resin, or a silicone-modified epoxy resin; (b) the acid anhydride curing agent is methyl It may be hexahydrophthalic anhydride (MHHPA) or hexahydrophthalic anhydride (HHPA); (c) the carbinol siloxane resin may be a compound of the following formula:

Wherein (R ¹ O) _m is an alkylene oxide group (when m = 1) or a poly (alkylene oxide) group (when m>1); R ¹ is independently —C ₂ H ₄ It represents a linear or branched divalent group selected from —, —C ₃ H ₆ —, and —C ₄ H ₈ —. It should be noted that when m is greater than 1, for example when 2 or more, the alkylene oxide groups can be the same or different to form poly (alkylene oxide) homopolymers, random copolymers, and block copolymers. . R ² and R ³ are independently H or C ₁ -C ₂ alkyl; R ⁴ is H or C ₁ -C ₂ alkyl and is the same as or different from R ² . In a preferred embodiment of the invention, R ² and R ⁴ may both be methyl. x is an integer from 1 to 100; y is an integer from 1 to 100; n is an integer from 1 to 5; and m is an integer from 1 to 40.

  For example, commercial products such as Silwet L-7608, CoatOSil 7604, BYK-373, BYK-377, and TEGOPREN 5842 can serve as the carbinol siloxane resin herein.

  In another sealing material composition of the present invention, in addition to the epoxy resin and the curing agent used as main components, in order to reduce the internal stress of the sealing material, it may further contain a carbinol siloxane resin, At the same time, a reactive UV absorber or a reactive hindered amine light stabilizer (HALS) having a reactive group may be selectively added. In addition, a reactive antioxidant and a phosphorus-containing flame retardant can be selectively used to improve the yellowing prevention performance of the encapsulant. Detailed information on (a) epoxy resin, (b) acid anhydride curing agent, and (c) carbinol siloxane resin is as described above. (D) The curing accelerator is a tetraalkylammonium salt such as tetraethylammonium bromide or tetra-n-butylammonium bromide; or tetraethylphosphonium bromide, tetra-n-butylphosphonium bromide, methyltributylphosphonium iodide, It may be a tetraalkylphosphonium salt such as methyltri-n-butylphosphonium dimethylphosphate or tetraethylphosphonium tetrafluoroborate. The reactive UV absorber may be a compound of the following formula:

Wherein p, q, w, and x are each independently an integer of 1 to 5; R is H or C ₁ -C ₈ alkyl; R ⁵ is a linear or branched C ₂ ~C ₄ alkyl. (F) The reactive hindered amine light stabilizer (HALS) may be a compound of the following formula:

  In the formula, y is an integer of 0 to 8.

  In addition, reactive antioxidants and phosphorus-containing flame retardants can act as additives that enhance the yellowing prevention performance of the sealant. The phosphorus-containing flame retardant may be, for example, triphenyl phosphite and 3,4: 5,6-dibenzo-2H-1,2-oxaphosphorin-2-oxide.

  The sealing material composition of the present invention comprises (1) low internal stress due to the addition of a carbinol siloxane resin; (2) addition of a UV absorber having a reactive group or a hindered amine light stabilizer (HALS), and reaction. Excellent anti-yellowing performance due to the addition of reactive antioxidants and phosphorus-containing flame retardants; and (3) long-term by forming polymeric UV absorbers and / or polymeric hindered amine light stabilizers in situ Advantageous in a number of aspects, such as anti-yellowing performance, and therefore reduced UV absorber content due to migration and high volatility of common low molecular weight UV absorbers and / or hindered amine light stabilizers Avoid the possibility.

[Example 1]
[Composition of Table 1] Main component

  The epoxy resin used here is bisphenol A diglycidyl ether (NPEL-128E, purchased from Nan Ya Plastics Company), and the acid anhydride curing agent used here is methyl hexa Hydrophthalic anhydride (MHHPA), the carbinol siloxane resin A used here is Silwet L-7608 (purchased from GE Silicone).

  Add a tetraalkylphosphonium salt (curing accelerator) into a curing agent (such as MHHPA in Table 1) at room temperature and stir to form a solution (about 0.5 hours), then add additional ingredients And stirred to obtain a uniform mixture. The obtained resin mixture was heated at 120 ° C. for 1.5 hours, and then heated at 140 ° C. for 3.5 hours to be cured.

The film thus formed was subjected to thermomechanical analysis (TMA, Perkin Elmer DMA7e) and subjected to internal stress (α ₂ / α ₁ ) values were measured. The results are listed in Table 1 below.

[Table 1]

[Example 2]
[Composition of Table 2] Main component

A method similar to that described in Example 1 was followed, except that Silwet L-7608 was replaced with CoatOSil 7604 (purchased from GE Silicone). The measured internal stress (α ₂ / α ₁ ) values are shown in Table 2 below.

[Table 2]

[Example 3]
[Composition of Table 3] Main component

Except that the carbinol siloxane resin C was BYK-373 (purchased from BYK), the internal stress (α ₂ / α ₁ ) value measured according to the same method as described in Example 1 Table 3 shows.

[Table 3]

From the results shown in Tables 1 to 3 above, the use of carbinol siloxane resins A, B and C reduces the hardness of the epoxy resin and reduces the internal stress caused by various thermal expansion coefficients of organic and inorganic materials. It is considered possible. Specifically, when the content of the carbinol siloxane resin increases, the internal stress (α ₂ / α ₁ ) value decreases. The difference in coefficient of thermal expansion above and below the glass transition temperature is reduced, which means that internal stress can be effectively reduced and the problems of encapsulant cracking and electronics shorts can be overcome.

[Example 4]
[Composition of Table 4] Main component

  The epoxy resin used here is bisphenol A diglycidyl ether (NPEL-128E, purchased from Nan Ya Plastics Company), and carbinol siloxane resin A is Silwet L- 7608 (purchased from GE Silicone), and the acid anhydride curing agent used here is methylhexahydrophthalic anhydride (MHHPA), and the reactive UVA (UV absorber) used here is SV8A. (A product of Everlight Chemical Industrial Corp.) and a general UVA used here is EV81 (manufactured by Everlight Chemical Industry).

  The resin mixture was prepared in the same manner as described in Example 1 except that the curing time was heated at 120 ° C. for 2 hours and then heated at 140 ° C. for 4 hours.

The film produced in Example 4 (thickness 3 mm) was then placed in a QUA accelerated weathering tester (Model QUV / SE solar Eye Irradiance Control), test conditions were temperature 70 ° C .; 340 nm; And 1.35 w / m ² . Using a spectrophotometer (SPECTROPHOTOMETER CM-3500d / Minolta), the yellowness index (YI) was measured before and after UV light irradiation, and ΔYI = YI / _t −YI / _t0 . The results are shown in Table 4 below.

[Table 4]

  In Table 4 above, “unsuitable” means that ΔYI value> 3.00 after 336 hours of exposure, and “suitable” means that ΔYI value <3.00 after 336 hours of exposure. To do.

[Example 5]
[Composition of Table 5] Main component

  Using the same method as described in Example 1, the effect of the hindered amine light stabilizer was measured. The reactive hindered amine light stabilizer in this example is IA38 (purchased from Nantong City Zhenxing Fine Chemical Co., Ltd., China), and the general hindered amine light stabilizer is EV77 (purchased from Everlight Chemical Industrial Corp.). The measured ΔYI values are shown in Table 5 below.

[Table 5]

  In Table 5 above, “unsuitable” means that ΔYI value> 3.00 after 336 hours of exposure, and “suitable” means that ΔYI value <3.00 after 336 hours of exposure. To do.

  According to the results shown in Tables 4 and 5 above, it was shown that an excellent yellowing prevention effect can be achieved by adding UVA having a reactive group and a hindered amine light stabilizer. Although the invention has been described in terms of its preferred embodiments, it is to be understood that many other possible improvements and modifications can be made without departing from the scope of the invention as claimed below.

Claims (9)

(A) 30-60% by weight of an epoxy resin;
(B) 30-60% by weight acid anhydride curing agent;
(C) 0.1-30% by weight of a carbinol siloxane resin capable of forming a homogeneous mixture with (a) and (b); and (d) 0.1-5% by weight of a reactive UV absorber or Reactive hindered amine light stabilizer (HALS):
A silicone-containing encapsulant composition that is a uniform mixture . The silicone-containing encapsulant composition of claim 1, wherein the carbinol siloxane resin is a compound of the following formula:
Where (R ¹ O) _m is an alkylene oxide group when m = 1, or a poly (alkylene oxide) group when m>1; R ¹ is independently —C ₂ Represents a linear and branched divalent group selected from H ₄ —, —C ₃ H ₆ —, and —C ₄ H ₈ —; when m is greater than 1, the alkylene oxide groups are the same Or different from each other to form poly (alkylene oxide) homopolymers, random copolymers, and block copolymers; R ² and R ³ are independently H or C ₁ -C ₂ alkyl; R ⁴ is H or C ₁ -C ₂ alkyl, identical or different from R ² ; x is an integer from 1 to 100; y is an integer from 1 to 100; n is an integer from 1 to 5; and m is It is an integer of 1-40. The silicone-containing encapsulant composition of claim 1, wherein the reactive UV absorber is at least one selected from compounds of the following formula:
Wherein p, q, w, and x are each independently an integer of 1 to 5; R is H or C ₁ -C ₈ alkyl; R ⁵ is a linear or branched C ₂ ~C ₄ alkyl. The silicone-containing encapsulant composition according to claim 1, wherein the reactive hindered amine light stabilizer (HALS) is:
In the formula, y is an integer of 0 to 8, and a silicone-containing sealing material composition. The silicone-containing encapsulant composition according to claim 1, wherein the silicone-containing encapsulant composition is used for LED encapsulation. (A) 30-60% by weight of an epoxy resin;
(B) 30-60% by weight acid anhydride curing agent;
(C) 0.1 to 30% by weight of a carbinol siloxane resin capable of forming a homogeneous mixture with (a) and (b);
(D) 0.01 to 3.0% by weight of a curing accelerator;
(E) 0.1-5 wt% reactive UV absorber; and (f) 0.1-5 wt% reactive hindered amine light stabilizer (HALS):
A silicone-containing encapsulant composition that is a uniform mixture . The silicone-containing encapsulant composition of claim 6, wherein the reactive UV absorber is at least one selected from compounds of the following formula:
Wherein p, q, w, and x are each independently an integer of 1 to 5; R is H or C ₁ -C ₈ alkyl; R ⁵ is a linear or branched C ₂ ~C ₄ alkyl. The silicone-containing encapsulant composition of claim 6, wherein the reactive hindered amine light stabilizer (HALS) is a compound of the following formula:
In the formula, y is an integer of 0 to 8. The silicone-containing encapsulant composition according to claim 6, wherein the silicone-containing encapsulant composition is used for LED encapsulation.