WO2012102414A1

WO2012102414A1 - Epoxy hybrid silicone resin composition

Info

Publication number: WO2012102414A1
Application number: PCT/KR2011/000482
Authority: WO
Inventors: Chang-Keun Seo; Min-Kyung SEO; Kwang-Su Choi
Original assignee: Daejoo Electronic Materials Co., Ltd.
Priority date: 2011-01-24
Filing date: 2011-01-24
Publication date: 2012-08-02

Abstract

An epoxy hybrid silicone resin composition of the present invention comprising a carboxyl modified polysiloxane, an epoxy resin, an acid anhydride, and a catalyst provides a cured product having improved properties in terms of heat resistance, adhesion strength, color stability, and crack resistance, and thus is useful as sealing agents, fillers, adhesives, and coating agents for an electrical and electronic device.

Description

EPOXY HYBRID SILICONE RESIN COMPOSITION

FIELD OF THE INVENTION The present invention relates to an epoxy hybrid silicone resin composition which provides a cured product having improved properties in terms of heat resistance, adhesion strength, color stability, and crack resistance.

BACKGROUND OF THE INVENTION

Curable resin compositions which provide cured products having improved electrical and mechanical properties are widely used as sealing agents, adhesives, paints, and coating agents for electrical and electronic devices. Epoxy resin and silicone resin compositions have been usually used in such applications.

Epoxy resin compositions, however, have a problem in that cured products obtained therefrom impose high stress to an electrical and electronic device due to their high elasticity modulus and strong rigidity, causing bending of the device, or creating inner cracks and gaps between the cured product and the device. In addition, when applied as sealing agents to light-emitting diodes (LED), they tend to undergo yellowing discoloration when cured, which leads to lowering of the brightness.

In order to obtain cured products that exerts low stress, Japanese Patent Laid-open Publication No. 1993-395084 discloses a curable resin composition comprising an epoxy group-containing silicone resin; and Japanese Patent Laid- open Publication Nos. 1995-22441 and 1995-118365, a die-bonding material consisting of a reaction product of an epoxy group-containing silicone oil and a phenol-based organic compound. However, cured products obtained from such compositions still exhibit unsatisfactory stress properties.

As for curable silicone resin compositions, they have been reported several problems, e.g., a condensation reaction-type requires a prolonged curing time, and an addition reaction-type does not undergo smooth curing when an reaction inhibitory materials such as sulfur, soldering, and flux, is present or when cured under an oxygen atmosphere. Also, generally, cured products obtained from conventional curable silicone compositions have relatively low heat resistance and adhesion strength, besides they are undesirably sticky, which lowers the working efficiency.

In order to overcome the above-mentioned problems, Japanese Patent Laid-open Publication No. 1994-306084 discloses a curable silicone resin composition consisting of an epoxy modified silicone oil and a phenol modified silicone oil; and Japanese Patent Laid-open Publication No. 1993-295084, a resin composition comprising an epoxy-containing organo-polysiloxane. However, the former requires an undesirably prolonged curing time, while a cured product obtained from the latter exhibits low adhesion strength and poor crack resistance due to its excessive rigidity.

SUMMARY OF THE INVENTIO

Accordingly, it is an object of the present invention to provide an epoxy hybrid silicone resin composition which provides a cured product having improved properties in terms of heat resistance, adhesion strength, color stability, and crack resistance.

In accordance with one aspect of the present invention, there is provided an epoxy hybrid silicone resin composition comprising:

(A) a carboxyl modified polysiloxane,

(B) an epoxy resin,

(C) an acid anhydride, and

(D) a catalyst. DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, unless otherwise stated or indicated, the term "alkyl" used herein denotes either a straight or branched saturated hydrocarbon radical chain having a carbon number of 1 to 6. Examples of said alkyl include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, n-pentyl, isopentyl, and hexyl, but are not limited thereto.

The term "alkoxy" used herein means a -OR_a group, wherein R_a is alkyl as defined above. Examples of said alkoxy include methoxy, difluoromethoxy, trifluoromethoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, and t-butoxy, but are not limited thereto.

The term "carboxyl ester" used herein refers to a -COOR_b group, wherein R_b is alkyl as defined above.

An epoxy hybrid silicone resin composition of the present invention is characterized in comprising (A) a carboxyl modified polysiloxane, (B) an epoxy resin, (C) an acid anhydride, and (D) a catalyst, preferably comprising (A) 20 to 90 % by weight of a carboxyl modified polysiloxane, (B) 4 to 45 % by weight of an epoxy resin, (C) 5 to 45 % by weight of an acid anhydride, and (D) 0.01 to 5 % by weight of a catalyst.

Hereinafter, each component is described in detail.

(A) Carboxyl modified polysiloxane

The carboxyl modified polysiloxane used in the present invention comprises at least one carboxyl group per one molecule, and may be synthesized by conducting a condensation reaction of (i) a polysiloxane comprising an alkyl group and optionally a phenyl group and (ii) a polyol comprising carboxyl and hydroxy groups in the presence of (iii) a reaction catalyst.

(i) Polysiloxane comprising an alkyl group and optionally a phenyl group The polysiloxane comprising an alkyl group and optionally a phenyl group may be represented by formula (I):

R'R^SiO^ (M unit) (I) wherein,

R¹ is C_1-6 alkyl;

R² is C_1-6 alkyl or phenyl; and

R³ is C 1.6 alkoxy or silanol.

The polysiloxane comprising an alkyl group and optionally a phenyl group may comprise alkyl and phenyl groups in a molar ratio ranging from 100:0 to 20:80. The polysiloxane may comprise either an alkoxy group or a silanol group in an amount ranging from 2 to 30% by mole, preferably 4 to 20% by mole.

It is preferred that the polysiloxane comprising an alkyl group and optionally a phenyl group has a refractive index of 1.4 to 1.6. When the refractive index is less than 1.4, lowering of the initial brightness may occur, and when more than 1.6, an excessively rigid cured product may be obtained, generating cracks.

Also, it is preferred that the polysiloxane comprising an alkyl group and optionally a phenyl group has a number average molecular weight (Mn) of 500 to 5000. When the number average molecular weight is less than 500, lowering of the curing property may occur, and when more than 5000, the viscosity may become too high, which makes the coating operation difficult.

The polysiloxane comprising an alkyl group and optionally a phenyl group may be synthesized by hydrolyzing a halogen silane or an alkoxy silane, followed by a condensation reaction of the resulting product in the presence of a hydrochloric acid or phosphoric acid catalyst.

Representative examples of the alkoxy silane include trimethoxy silane, triethoxy silane, phenyltrimethoxy silane, phenyltriethoxy silane, methyltrimethoxy silane, methyltriethoxy silane, ethyltrimethoxy silane, ethyltriethoxy silane, propyltrimethoxy silane, propyltriethoxy silane, dimethyldimethoxy silane, diphenyldimethoxy silane, methylphenyldimethoxy silane, trimethylmethoxy silane, dimethylphenylmethoxy silane, methyldiphenylmethoxy silane, triphenylmethoxy silane, and a mixture thereof. Specifically, they may be used DC-3037, DC-3074 and Z-6018 commercially available from Dow Corning Co.; KR-213, KR-216, KR-217 and KR-9218 commercially available from Shinetsu Co.; SJ1000A and SC5000A commercially available from KCC Co.; SY-231 commercially available from WACKER Co.; and a mixture thereof. Suitable for use in the present invention is a halogen silane such as chlorosilane.

(ii) Polyol comprising carboxyl and hydroxy groups

The polyol comprising carboxyl and hydroxy groups may comprise at least one carboxyl group and at least two hydroxy groups per one molecule, and may be represented by formula (II):

R⁴R⁵C(R⁶)₂ (II) wherein,

R⁴ is C].₆ alkyl;

R⁵ is carboxyl ester; and

R⁶ is methylol.

The polyol may preferably have a number average molecular weight (Mn) of 100 to 1000.

The polyol may be synthesized by subjecting an acid anhydride to a ring-open reaction with a multi-valence alcohol. Suitable for use in the present invention is a multi-valence alcohol having at least two hydroxy groups, and representative examples thereof include glycerin, trimethylolpropane, trimethylolethane, triethanolamine, trihydroxyisocyanurate, pentaerythritol, dimethylolpropionic acid, dimethylolbutanoic acid, and a mixture thereof. The acid anhydride used in the present invention may be any one which is capable of bringing out a ring-open reaction with a hydroxy group, and representative examples thereof include phthalic acid anhydride, tetrahydrophthalic acid anhydride, hexahydrophthalic acid anhydride, methyltetrahydrophthalic acid anhydride, methylhexahydrophthalic acid anhydride, trimellitic acid anhydride, succinic acid anhydride, maleic acid anhydride, and a mixture thereof.

The acid anhydride may be preferably used in an amount ranging from 0.5 to 1.5 moles based on 1 mole of the multi-valence alcohol. When the amount is less than 0.5 moles, lowering of the crosslinking density of the polyol may occur, and when more than 1.5 moles, the viscosity of the polyol and the crosslinking density of the polysiloxane may become too high.

The ring-open reaction between the acid anhydride and the multi- valence alcohol may be conducted at a temperature of 100°C or higher without a catalyst, but, if necessary, a metal organic compound may be used as a catalyst of the ring-open reaction. Examples of such a metal organic compound include tin-based organic compounds such as dibutyl tin oxide and dibutyl tin dilaurylate; titanium-based organic compounds such as tetraisopropyl titanate and tetrabutyl titanate; and a mixture thereof. (iii) Reaction catalyst

Suitable for use as a reaction catalyst in preparing the carboxyl modified polysiloxane is a metal organic compound comprising at least one metal selected from the group consisting of titanium, aluminum, zirconium, tin, vanadium and molybdenum. Representative examples of the metal organic compound catalyst include titanium-based organic compounds such as tetrabutyl titanate, tetraisopropyl titanate and titanate chilate; aluminum-based organic compounds such as aluminum tris(ethylacetoacetate); zirconium-based organic compounds such as zirconium tetrabutylate; tin-based organic compounds such as dibutyl tin diacetate; vanadium-based organic compounds such as vanadium oxide; molybdenum-based organic compounds such as molybdenum hexacarbonyl; and a mixture thereof. It is preferred that the carboxyl modified polysiloxane has a refractive index of 1.4 to 1.6. When the refractive index is less than 1.4, lowering of the initial brightness may occur, and when more than 1.6, an excessively rigid cured product may be obtained, generating cracks.

The carboxyl modified polysiloxane (A) may be used in an amount ranging from 20 to 90% by weight based on a total amount of the inventive composition. When the amount is less than 20% by weight, the increasing effect in heat resistance and stability may be imperceptible, and when more than 90% by weight, the hardness of a cured product may decrease and cracks with use time may occur, due to the low crosslinking density.

(B) Epoxy resin The epoxy resin used in the present invention comprises at least two epoxy functional groups per one molecule, and representative examples thereof include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol F type epoxy resins based on cyclic ring-containing epoxy resins, hydrogen-added and bisphenol A type epoxy resins, novolac type epoxy resins, hydroquinone type epoxy resins, and a mixture thereof. Among them, preferred are bisphenol A type and bisphenol F type epoxy resins having an epoxy equivalent of 150 to 300, more preferably 180 to 300, cyclic ring- containing epoxy resins having an epoxy equivalent of at least 500, and novolac phenol type epoxy resins having an epoxy equivalent of 150 to 300.

The epoxy resin may preferably have a number average molecular weight (Mn) of below 500.

If necessary, for the purpose of controlling a viscosity of the epoxy resin, the inventive composition may further comprise glycol ether oxiranes as a reactive diluent. The glycol ether oxiranes may be prepared by reacting glycols having at least two functional groups with epichlorohydrin, and representative examples thereof include ethylene glycol diglycidyl ether, neopentyl glycol diglycidyl ether, 1,4-butylene glycol diglycidyl ether, 1,6- hexanediol diglycidyl ether, trimethylol propane triglycidyl ether, glycerin triglycidyl ether, and a mixture thereof.

The epoxy resin (B) may be used in an amount ranging from 4 to 45% by weight, preferably 5 to 45% by weight, based on a total amount of the inventive composition.

(C) Acid anhydride

The acid anhydride used in the present invention acts as a curing agent, and it may be preferably a cycloaliphatic acid anhydride having a cycloaliphatic ring, which is prepared by adding hydrogen to an aromatic acid anhydride. Suitable for use in the present invention is an acid anhydride such as methylhexahydrophthalic acid anhydride which is present in a liquid phase at room temperature, hexahydrophthahc acid anhydride which melts at slight heat, hydrogen-added nadic acid anhydride, hydrogen-added methylnadic acid anhydride, and a mixture thereof.

If necessary, in combination with the acid anhydride, tetrahydrophthalic acid, methyl tetrahydrophthalic acid anhydride, nadic acid anhydride or an oligomer having at least one carboxyl group may be further employed.

The acid anhydride (C) may be used in an amount ranging from 5 to

45% by weight based on a total amount of the inventive composition.

(D) Catalyst The catalyst used in the present invention functions to accelerate a reaction between epoxy functional groups of the epoxy resin and the acid anhydride, and it may be preferably a metal organic compound comprising at least one metal selected from the group consisting of tin, titanium, zinc, aluminum, zirconium, vanadium and molybdenum, or a quaternary organic phosphonium salt.

Representative examples of the metal organic compound catalyst include tin-based organic compounds such as dibutyl tin oxide, dibutyl tin laurylate and dibutyl tin diacetate; titanium-based organic compounds such as tetrabutyl titanate, tetraisopropyl titanate and titanate chilate; zinc-based organic compounds such as zinc acetate; aluminum-based organic compounds such as aluminum tris(ethylacetoacetate); zirconium-based organic compounds such as zirconium tetrabutylate; vanadium-based organic compounds such as vanadium oxide; molybdenum-based organic compounds such as molybdenum hexacarbonyl; and a mixture thereof. Among them, it is preferred a metal organic compound comprising at least one metal selected from the group consisting of tin, titanium and zinc, more preferred a tin-based or titanium- based organic compound.

Representative examples of the quaternary organic phosphonium salt catalyst include benzyltributylphosphonium chloride, tetrabutylphosphonium chloride, tetrabutylphosphonium bromide, tetrabutylphosphonium iodide, tetrametylphosphonium bromide, tetraethylphosphonium chloride, ethylenebis(triphenylphosphonium bromide), benzyltriphenylphosphonium chloride, tetraphenylphosphonium chloride, and a mixture thereof.

The catalyst (C) may be used in an amount ranging from 0.01 to 5% by weight based on a total amount of the inventive composition. The inventive epoxy hybrid silicone resin composition may be prepared by mixing the components (A) to (D) at once; or by (1) mixing a part of the component (A) and the component (B) to form a first resin mixture (PART-A), (2) mixing the remainder of the component (A), the component (C) and the component (D) to form a second resin mixture (PART-B), and (3) finally mixing the first and second resin mixtures. Wherein, any one of step (1) and step (2) may be first conducted.

The inventive epoxy hybrid silicone resin composition prepared thus can provide a cured product having improved properties in terms of heat resistance, adhesion strength, color stability, and crack resistance. Accordingly, the inventive resin composition can be widely employed as lightings of organic light-emitting diodes (OLEDs), white organic light-emitting diodes (WOLEDs) and light-emitting diodes (LEDs), and as sealing agents, fillers, adhesives, and coating agents for an electrical and electronic device including sensors and other optical devices, especially LEDs.

The following Examples are intended to further illustrate the present invention without limiting its scope.

Preparation Example 1-1: Preparation of a polyol comprising carboxyl and hydroxy groups (PE-1) 407.7 g of trimethylolpropane, 462.6 g of hexahydrophthalic acid, and

0.46 g of dibutyl tin dilaurylate as a reaction catalyst were added to a 1L 4- neck flask equipped with a stirrer. Under a nitrogen atmosphere, the mixture was allowed to react at 140°C for 2 hrs (a ring-open reaction). After completion of the reaction, the resulting mixture was quenched, to obtain a polyol comprising carboxyl and hydroxy groups (PE- 1 ).

Preparation Examples 1-2 to 1-5: Preparation of polyols comprising carboxyl and hydroxy groups (PE-2 to PE-5)

The procedure of Preparation Example 1-1 was repeated employing the compounds and amounts shown in Table 1, to obtain various polyols comprising carboxyl and hydroxy groups (PE-2 to PE-5).

Preparation Example 2-1: Preparation of carboxyl modified polysiloxane (SI-1)

400 g of DC-3037 ((i) a polysiloxane comprising an alkyl group and a phenyl group), 100 g of PE-1 prepared in Preparation Example 1-1 ((ii) a polyol comprising carboxyl and hydroxy groups), and 0.2 g of tetrabutoxy titanate ((iii) a reaction catalyst) were added to a 1L flask equipped with a stirrer, which was allowed to react. The resulting mixture was heated to 160°C to remove methanol therefrom, which led to the carboxyl modified polysiloxane (SI-1, refractive index: 1.52). Preparation Examples 2-2 to 2-5: Preparation of carboxyl modified polysiloxane (SI-2 to SI-5)

The procedure of Preparation Example 2-1 was repeated employing the compounds and amounts shown in Table 2, to obtain various carboxyl modified polysiloxanes (SI-2 to SI-5). <Table 2>

Example 1: Preparation of epoxy hybrid silicone resin composition

Step 1 : Preparation of first resin mixture (PART- A) (SHE-1

70% by weight of SI-1 prepared in Preparation Example 2-1 and 30% by weight of 3,4-epoxycyclohexylmethyl-3,4-epoxy-cyclohexane-carboxylate (CEL2021P, Dicell Chemical Co.,) as an epoxy resin having epoxy functional groups were mixed to prepare the first resin mixture (SHE-1).

Step 2: Preparation of second resin mixture (PART-B) (SHA-1)

70% by weight of SI-1 prepared in Preparation Example 2-1, 29.7% by weight of methylhexahydrophthalic acid anhydride (MHHPA, Shin Nippon Iwa Co.,), and 0.3% by weight of a quaternary phsphonium salt (U-CAT5003, San Apro Co.,) catalyst were mixed to prepare the second resin mixture (SHA- 1).

Step 3: Preparation of epoxy hybrid silicone resin composition The first resin mixture (PART-A) prepared in Step 1 and the second resin mixture (PART-B) prepared in Step 2 were mixed in a weight ratio of 50:50 to prepare the epoxy hybrid silicone resin composition, followed by vacuum-degassing.

Examples 2 to 5: Preparation of epoxy hybrid silicone resin composition

The procedure of Example 1 was repeated employing the compounds and amounts shown in Tables 3 and 4, to obtain various first resin mixtures (PART- A) and second resin mixtures (PART-B), respectively, and mixing the first resin mixture (PART-A) and the second resin mixture (PART-B) in a weight ratio of 50:50 (see Table 5), to prepare various epoxy hybrid silicone resin compositions.

Comparative Example 1: Preparation of epoxy resin composition

50% by weight of an epoxy resin (EHPE-3150CE, Dicell Chemical Co.,), 40% by weight of methylhexahydrophthalic acid anhydride (MHHPA, Shin Nippon Iwa Co.,), and 10% by weight of a butyl triphenylphosphonium chloride (BTPPCL) catalyst were mixed to prepare the resin composition.

Experimental Example; Evaluation on properties of resin compositions

Each of the resin compositions prepared in Examples 1 to 5 and Comparative Example 1 was coated as a sealing agent on LED on which an LED chip and a lead frame were placed, which was subjected to curing at 80 °C for 1 hr and 160°C for 4 hrs sequentially. Properties of the cured product thus obtained were measured as follows, and the results were shown in Tables 6 and 7.

(1) Surface sticky phenomenon

It was evaluated whether the surface of the cured product was sticky or not.

(2) Appearance

A color change of the cured product was observed at eyes.

(3) Hardness

A hardness of the cured product was measured using a SHORE D hardness testing machine.

(4) Glass transition temperature (Tg, °C)

A Glass transition temperature of the cured product was measured using a differential scanning calorimeter (DSC).

Ex.1 Ex.2 Ex.3 Ex.4 Ex.5

Sticky X X X X X phenomenon

Appearance Colorless, Colorless, Colorless, Colorless, Colorless, transparent transparent transparent transparent transparent

Hardness 53 45 36 25 67 As shown in Table 6, the epoxy hybrid silicone resin compositions prepared in Examples 1 to 5 provided cured products having no surface sticky phenomenon, high color stability and high crack resistance.

As shown in Table 7, the epoxy hybrid silicone resin compositions prepared in Examples 1 and 4 provided cured products having improved heat resistance and high crack resistance, as compared to that of Comparative Example 1 , which suggests that the inventive resin composition is very suitable for use in sealing or coating an LED.

While the invention has been described with respect to the above specific embodiments, it should be recognized that various modifications and changes may be made to the invention by those skilled in the art which also fall within the scope of the invention as defined by the appended claims.

Claims

What is claimed is;

1. An epoxy hybrid silicone resin composition comprising:

(A) a carboxyl modified polysiloxane,

(B) an epoxy resin,

(C) an acid anhydride, and

(D) a catalyst.

2. The epoxy hybrid silicone resin composition of claim 1 , which comprises:

(A) 20 to 90 % by weight of the carboxyl modified polysiloxane,

(B) 4 to 45 % by weight of the epoxy resin,

(C) 5 to 45 % by weight of the acid anhydride, and

(D) 0.01 to 5 % by weight of the catalyst.

3. The epoxy hybrid silicone resin composition of claim 1 , wherein the carboxyl modified polysiloxane has a refractive index of 1.4 to 1.6.

4. The epoxy hybrid silicone resin composition of claim 1, wherein the carboxyl modified polysiloxane is synthesized by conducting a condensation reaction of (i) a polysiloxane comprising an alkyl group and optionally a phenyl group and (ii) a polyol comprising carboxyl and hydroxy groups in the presence of (iii) a reaction catalyst.

5. The epoxy hybrid silicone resin composition of claim 4, wherein the polysiloxane comprising an alkyl group and optionally a phenyl group is represented by formula (I):

R'R^SiOys (M unit) (I) wherein,

R¹ is C_1-6 alkyl;

R² is C_1-6 alkyl or phenyl; and

R³ is C_1- alkoxy or silanol.

6. The epoxy hybrid silicone resin composition of claim 4, wherein the polyol comprising carboxyl and hydroxy groups is represented by formula (II):

R R⁵C(R⁶)₂ (II) wherein,

R⁴ is C_1-6 alkyl;

R⁵ is carboxyl ester; and

R⁶ is methylol.

7. The epoxy hybrid silicone resin composition of claim 4, wherein the polyol comprising carboxyl and hydroxy groups is synthesized by subjecting an acid anhydride to a ring-open reaction with a multi- valence alcohol.

8. The epoxy hybrid silicone resin composition of claim 7, wherein the acid anhydride is used in an amount ranging from 0.5 to 1.5 moles based on 1 mole of the multi-valence alcohol.

9. The epoxy hybrid silicone resin composition of claim 4, wherein the reaction catalyst is a metal organic compound comprising at least one metal selected from the group consisting of titanium, aluminum, zirconium, tin, vanadium and molybdenum.

10. The epoxy hybrid silicone resin composition of claim 1, wherein the epoxy resin is selected from the group consisting of bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol F type epoxy resins based on cyclic ring-containing epoxy resins, hydrogen-added and bisphenol A type epoxy resins, novolac type epoxy resins, hydroquinone type epoxy resins, and a mixture thereof.

11. The epoxy hybrid silicone resin composition of claim 1, wherein the acid anhydride is selected from the group consisting of methylhexahydrophthalic acid anhydride, hexahydrophthalic acid anhydride, hydrogen-added nadic acid anhydride, hydrogen-added methylnadic acid anhydride, and a mixture thereof.

12. The epoxy hybrid silicone resin composition of claim 1 , wherein the catalyst is a metal organic compound comprising at least one metal selected from the group consisting of tin, titanium, zinc, aluminum, zirconium, vanadium and molybdenum, or a quaternary organic phosphonium salt.

13. The epoxy hybrid silicone resin composition of claim 1, which further comprises glycol ether oxiranes as a reactive diluent.

14. The epoxy hybrid silicone resin composition of claim 1, which is employed as sealing agents, fillers, adhesives, or coating agents for an electrical and electronic device.