JP2008075081A - Resin composition and optical member using cured product thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a curable resin composition comprising an acrylic polymer, with which an optical member excellent in light resistance, heat resistance and mounting reliability can be formed. <P>SOLUTION: The resin composition comprises (A) the acrylic polymer obtained by reacting an unsaturated carboxylic acid with at least a part of epoxy groups in a copolymer obtained by copolymerizing monomers comprising (a) an epoxy group-containing (meth)acrylate, (b) a non-silicone polymerizable monomer having one polymerizable unsaturated bond and (c) a siloxane structure-containing (meth)acrylate, and (d) a hydroxy group-containing (meth)acrylate, (B) a polymerizable monomer having a polymerizable unsaturated bond and (C) a radical polymerization initiator. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a resin composition and an optical member using a cured product thereof.

  The optical member is used as a transparent member in a member used as a transparent substrate, a lens or an optical waveguide, or in an optical semiconductor element such as a light emitting diode (LED), a phototransistor, a photodiode, or a solid-state imaging device.

  Conventionally, many epoxy resins have been used as optical member resins. In general, a cured product of an epoxy resin has high transparency in the visible range, but often does not exhibit sufficient transparency in the ultraviolet to near-ultraviolet range. By using an alicyclic epoxy resin such as alicyclic bisphenol A diglycidyl ether, a cured product having relatively high transparency in the ultraviolet to near ultraviolet region can be obtained, but there is a problem that it is easily colored by heat or light. Yes (Patent Documents 1 and 2).

  Therefore, in recent years, application of silicone resins having excellent transparency and light resistance to optical member applications has been studied (Patent Document 3). However, the silicone resin is expensive and generally has a low elastic modulus and a large linear expansion coefficient, so that it is difficult to apply depending on the application. In addition, there is a concern that the silicone resin has low adhesion to other materials.

On the other hand, an acrylic polymer that is excellent in transparency and light resistance and is relatively inexpensive, such as PMMA polymerized with methyl methacrylate, may be used for optical members.
JP 2003-171439 A JP 2004-75894 A JP 2004-2810 A

  However, in the case of the conventional acrylic polymer, although it is superior to the epoxy resin in terms of transparency and light resistance in the ultraviolet to near ultraviolet region, it is not always sufficient in terms of heat resistance. In particular, in the case of an optical member used in the field of optical / electronic equipment, since it receives a large thermal history during mounting process on an electronic substrate or the like under high temperature operation, in order to apply an acrylic polymer to such use, it is It is strongly demanded that coloring when exposed is sufficiently suppressed and sufficient mounting reliability is expressed. If the mounting reliability is not sufficient, problems such as the occurrence of cracks are likely to occur when exposed to a cold temperature cycle.

  Furthermore, in recent years, the use of high-intensity laser light, blue light, and near-ultraviolet light has been spreading in the field of optical and electronic equipment, and in order to suppress a decrease in transmittance when receiving such light, There is a demand for an optical member that is superior in terms.

  Therefore, an object of the present invention is to provide a curable resin composition containing an acrylic polymer that can form an optical member excellent in light resistance, heat resistance, and mounting reliability. .

  The resin composition according to the present invention comprises (A) (a) an epoxy group-containing (meth) acrylate, (b) a non-silicone polymerizable monomer having one polymerizable unsaturated bond, and (c) a siloxane structure. An acrylic resin obtained by reacting an unsaturated carboxylic acid with at least a part of an epoxy group in a copolymer obtained by copolymerization of a monomer containing a (meth) acrylate containing (meth) acrylate and a hydroxyl group-containing (meth) acrylate It contains a polymer, (B) a polymerizable monomer having a polymerizable unsaturated bond, and (C) a radical polymerization initiator.

  The resin composition according to the present invention contains (A) an acrylic polymer having the above specific structure, (B) a polymerizable monomer, and (C) a radical polymerization initiator. It is possible to form an optical member that is excellent in terms of performance and mounting reliability.

  The copolymer is based on the total monomer units in the copolymer, (a) 10 to 65 mol% of an epoxy group-containing (meth) acrylate, (b) 20 to 75 mol% of a polymerizable monomer, (C) A copolymer copolymerized at a copolymerization ratio of 10 to 65 mol% of a siloxane structure-containing (meth) acrylate and (d) a hydroxyl group-containing (meth) acrylate of 5 to 60 mol% is preferable.

  The equivalent ratio of the carboxyl group of the unsaturated carboxylic acid to be reacted with the epoxy group in the copolymer is preferably 0.95 to 1.1 with respect to the equivalent of the epoxy group in the copolymer.

  (A) The epoxy group-containing (meth) acrylate is preferably glycidyl (meth) acrylate.

  (C) The siloxane structure-containing (meth) acrylate is preferably a compound represented by the following general formula (1).

In the formula, n ¹ represents an integer of 0 to 10, n ² represents an integer of 0 to 150, and R ¹ represents a hydrogen atom, an alkyl group having 1 to 9 carbon atoms, an aryl group, or a trialkylsilyloxy group. And a plurality of R ¹ in the same molecule may be the same or different, and R ² represents a hydrogen atom or a methyl group.

(D) The hydroxyl group-containing (meth) acrylate is preferably a compound represented by the following general formula (2a) or (2b). In formula (2a), m ¹ represents an integer of 0 to 20, and R ³ represents a hydrogen atom or a methyl group. In formula (2b), m ² and m ³ each independently represent an integer of 0 to 20, and R ⁴ represents a hydrogen atom or a methyl group.

  The optical member according to the present invention comprises a cured product obtained by curing any of the above resin compositions. The optical member according to the present invention has excellent light resistance, heat resistance, and mounting reliability.

  According to the resin composition according to the present invention, it is possible to form a cured product having high optical transparency and excellent light resistance, heat resistance, and mounting reliability. The cured product of the resin composition according to the present invention has a small decrease in light transmittance after high-temperature storage, and the occurrence of defective products in the thermal cycle test when used as an optical member is sufficiently suppressed. Therefore, the resin composition according to the present invention can be suitably used for electronic material applications such as an optical semiconductor sealing resin. In addition, by applying the cured product of the resin composition according to the present invention to an optical member, it is possible to improve the life and reliability of the optical element because of good heat resistance and light resistance.

  Hereinafter, preferred embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments. In the present specification, (meth) acrylate means acrylate and the corresponding methacrylate.

  The resin composition according to this embodiment contains at least (A) an acrylic polymer, (B) a polymerizable monomer having a polymerizable unsaturated bond, and (C) a radical polymerization initiator. This resin composition is cured by a radical polymerization reaction to form a cured product. This hardened | cured material has high optical transparency of the grade which can be used as an optical member. Specifically, for example, the transmittance of 400 nm light that passes through a 1 mm thick cured product is preferably 70% or more. If a component having a strong absorption band at 400 nm is not blended in the resin composition, and if each component of the resin composition is selected to be compatible with each other before curing, the transmittance as described above is usually used. A cured product is formed.

  The acrylic polymer (A) is composed of (a) an epoxy group-containing (meth) acrylate, (b) a non-silicone polymerizable monomer having one polymerizable unsaturated bond (polymerized in one molecule). Epoxy group in a copolymer obtained by copolymerization of a monomer containing an unsaturated compound containing one ionic unsaturated bond), (c) a siloxane structure-containing (meth) acrylate, and (d) a hydroxyl group-containing (meth) acrylate. It is a polymer obtained by making unsaturated carboxylic acid react with at least one part. An unsaturated group is introduced into the side chain of the acrylic polymer by the reaction between the epoxy group of the copolymer and the unsaturated carboxylic acid. That is, the acrylic polymer is a copolymer having a siloxane structure derived from a siloxane structure-containing (meth) acrylate in the main chain and an unsaturated group derived from an unsaturated carboxylic acid as a side chain. The unsaturated group of the acrylic polymer undergoes radical polymerization together with the polymerizable monomer of the component (B) when the resin composition is cured. Thus, the present inventors have found that a crosslinked structure is formed after curing, and a cured product having good heat resistance is formed. Further, by using the acrylic polymer in combination with the monomer, curing shrinkage is reduced as compared with the case where only the monomer such as polymethyl methacrylate is used. Furthermore, since the siloxane structure derived from the component (c) is introduced into the acrylic polymer, the transparency and light resistance of the cured product are improved. Moreover, the toughness of the cured product is also improved by introducing a siloxane structure. In addition, since the hydroxyl group derived from the component (d) is introduced into the acrylic polymer, the mounting reliability of the optical member is improved.

  In general, the compatibility between a monomer having a siloxane structure and a monomer such as methyl methacrylate is low. In the case of an acrylic resin, it is not possible to introduce a siloxane structure into a cured product while maintaining the transparency of the cured product. Although it was difficult in the past, by using the component (A) having a specific structure, it became possible to form a cured product having excellent light resistance while maintaining high optical transparency.

  (A) An epoxy group-containing (meth) acrylate is a monomer having an epoxy group and a (meth) acrylate group. Preferable specific examples of the epoxy group-containing (meth) acrylate include glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate glycidyl ether. Among these, glycidyl methacrylate is preferable.

  (B) The non-silicone polymerizable monomer having one polymerizable unsaturated bond is not particularly limited as long as it is a polymerizable monomer having no siloxane structure in which silicon atoms and oxygen atoms are alternately bonded. Used without limitation. However, a monomer different from (a) epoxy group-containing (meth) acrylate and (d) hydroxyl group-containing (meth) acrylate is used as component (b). Examples of the polymerizable monomer (b) include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, ethylhexyl ( (Meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, ethoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxybutyl ( (Meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-methoxyethoxy (meth) acrylate, 2-ethoxyethoxy (meth) acrylate, methoxydiethylene glycol (meth) acrylate, ethoxydiethyl Glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, butoxytriethylene glycol (meth) acrylate, methoxypropylene glycol (meth) acrylate, pyrenoxide adduct (meth) acrylate, octafluoropentyl (meth) acrylate, N , N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, cyclohexyl mono (meth) acrylate and mono (meth) acrylate having tricyclodecane. These may be used alone or in combination of two or more.

(C) Siloxane structure-containing (meth) acrylate is a monomer having a siloxane structure in which silicon atoms and oxygen atoms are alternately bonded, and a (meth) acrylate group. The siloxane structure is, for example, a divalent group represented by the following general formula (3). ^{R 1} and ^{n 2} in the formula (3) has the same meaning as ^{R 1} and ^{n 2} in the formula (1), including preferred embodiments thereof.

The siloxane structure-containing (meth) acrylate is preferably a compound represented by the general formula (1). In formula (1), n ¹ represents an integer of 0 to 10, n ² represents an integer of 0 to 150 (preferably 0 to 30), R ¹ represents a hydrogen atom, an alkyl group having 1 to 9 carbon atoms, An aryl group or a trialkylsilyloxy group is shown. R ¹ is preferably an alkyl group having 1 to 9 carbon atoms, and most typically R ¹ is a methyl group.

Specific examples of the siloxane structure-containing (meth) acrylate of the formula (1) include n ¹ = 3, n ² = 0, R ¹ = trimethylsilyloxy group 3-methacryloxypropyltris (trimethylsiloxy) silane, n ¹ = 3, n ² = 27, R ¹ = Methyl group one-end methacryl-modified silicone oil (functional group equivalent 2100), n ¹ = 3, n ² = 61, R ¹ = Methyl-group one-end methacryl-modified Examples thereof include silicone oil (functional group equivalent 4600), ^one -terminal methacryl-modified silicone oil (functional group equivalent 12000) in which n ¹ = 3, n ² = 161, and R ¹ = methyl group. Among these, from the viewpoint of compatibility with a solvent and the like, 3-methacryloxypropyltris (trimethylsiloxy) silane, and ^one -terminal methacryl-modified silicone oil in which n ¹ = 3, n ² = 27, and R ¹ = methyl group Is preferred. These may be used alone or in combination of two or more.

  (D) Hydroxyl group-containing (meth) acrylate is a monomer having a hydroxyl group and a (meth) acrylate group. The hydroxyl group-containing (meth) acrylate is preferably a compound represented by the general formula (2a) or (2b). More specifically, (d) hydroxyl group-containing (meth) acrylates are 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meta). ), At least one monomer selected from the group consisting of 6-hydroxyhexyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate and 2-hydroxybutyl (meth) acrylate. These may be used alone or in combination of two or more.

  The weight average molecular weight of the copolymer obtained by copolymerizing the monomer containing the component (a), the component (b), the component (c) and the component (d) is preferably 1000 to 50000, 2000 More preferably, it is -4000. If this weight average molecular weight is less than 1000, the mechanical properties (bending strength, flexibility) and optical properties of the cured product formed from the resin composition tend to deteriorate, and if it exceeds 50,000, the acrylic polymer (B) It tends to be difficult to be compatible with the component polymerizable monomer.

  A copolymer having a weight average molecular weight of 1,000 to 50,000, as understood by those skilled in the art, adjusts the presence or absence of a chain transfer agent during polymerization, the type and amount of a radical polymerization initiator, the polymerization temperature, and the like. Obtained by. For example, when a chain transfer agent is used, a large amount of radical polymerization initiator is added, or the reaction is performed under higher temperature conditions, the weight average molecular weight of the copolymer tends to be low.

The weight average molecular weight is measured by gel permeation chromatography (GPC) using a standard polystyrene calibration curve. Examples of measurement conditions are shown below.
Equipment using GPC conditions: Hitachi L-6000 (manufactured by Hitachi, Ltd.)
Column: Gel pack GL-R420 + Gel pack GL-R430 + Gel pack GL-R440 (3 in total) (all manufactured by Hitachi Chemical Co., Ltd., trade name)
Eluent: Tetrahydrofuran Measurement temperature: 40 ° C
Flow rate: 1.75 ml / min.
Detector: L-3300RI (manufactured by Hitachi, Ltd.)

The copolymer is obtained by copolymerizing the component (a), the component (b), the component (c) and the component (d) by a known method such as a solution polymerization method in the presence of a radical polymerization initiator. Is obtained. More specifically, for example, a solvent is placed in a reaction vessel and heated to 140 ° C. with stirring under a pressure of 0.15 MPa (1.5 kgf / cm ² ) in a nitrogen gas atmosphere. A copolymer is obtained by uniformly dropping a liquid mixture comprising the component (a), the component (b), the component (c), the component (d) and the radical polymerization initiator, and continuing the reaction after the completion of the dropwise addition.

  As the radical polymerization initiator used in the copolymerization, any one that can be used for normal radical polymerization, such as an azo initiator and a peroxide initiator, can be used. Examples of azo initiators are azobisisobutyronitrile, azobis-4-methoxy-2,4-dimethylvaleronitrile, azobiscyclohexanone-1-carbonitrile and azodibenzoyl. Examples of peroxide initiators include benzoyl peroxide, lauroyl peroxide, di-t-butylperoxyhexahydroterephthalate, t-butylperoxy-2-ethylhexanoate, 1,1-t-butylperoxy There are -3,3,5-trimethylcyclohexane, t-butylperoxyisopropyl carbonate and di-t-hexyl peroxide.

  The blending ratio of the component (a) at the time of copolymerization is 10 to 65 mol% with respect to the total number of moles of the component (a), the component (b), the component (c) and the component (d). Preferably, it is 20-55 mol%. If this blending ratio is less than 10 mol% or exceeds 65 mol%, the bending strength and flexibility of the cured product formed from the resin composition tend to decrease.

  The blending ratio of the component (b) at the time of copolymerization is 20 to 75 mol% with respect to the total number of moles of the components (a), (b), (c) and (d). Preferably, it is 30-65 mol%. When this compounding ratio is less than 20 mol% or exceeds 75 mol%, the bending strength and flexibility of the cured product formed from the resin composition tend to be lowered.

  The blending ratio of the component (c) at the time of copolymerization is 10 to 65 mol% with respect to the total number of moles of the component (a), the component (b), the component (c) and the component (d). Preferably, it is 20-55 mol%. If this blending ratio is less than 10 mol% or exceeds 65 mol%, the bending strength and flexibility of the cured product formed from the resin composition tend to decrease.

  The blending ratio of the component (d) at the time of copolymerization is 5 to 60 mol% with respect to the total number of moles of the components (a), (b), (c) and (d). Preferably, it is 15-50 mol%. When this compounding ratio is less than 5 mol% or exceeds 60 mol%, the mounting reliability of the optical member tends to be lowered.

  The ratio of each monomer unit in the copolymer produced by copolymerization of the component (a), the component (b), the component (c) and the component (d) is usually the above blending ratio in the copolymerization. Substantially the same.

  By reacting the epoxy group in the copolymer with an unsaturated carboxylic acid, (A) an acrylic polymer is obtained. As the unsaturated carboxylic acid, (meth) acrylic acid is typically used.

  In this reaction, the copolymer and the unsaturated carboxylic acid are mixed at a ratio such that (epoxy group in the copolymer) / (carbonyl group of the unsaturated carboxylic acid) is 0.95 to 1.1 in an equivalent ratio. It is preferable to react. If this ratio is less than 0.95, the mechanical properties of the cured product tend to deteriorate due to the effect of excess unsaturated carboxylic acid, and if it exceeds 1.1, the curability and storage stability of the resin composition are general. Tend to decline.

  The above reaction can be carried out in the presence of a basic catalyst (for example, N, N′-diethylcyclohexylamine, triethylamine and triethanolamine) or a phosphorus-based catalyst (for example, triphenylphosphine). The reaction conditions are, for example, 105 ° C. and 8 to 10 hours.

  By refine | purifying the produced | generated acrylic polymer, the light resistance and heat-resistant coloring property of hardened | cured material can further be improved. As a purification method, it can be performed by a known purification method, for example, it can be purified by a reprecipitation method. In the reprecipitation method, for example, an acrylic polymer solution is added dropwise to a 10-fold amount of a poor solvent (methanol: water = 50: 50) while stirring, and the supernatant is removed after completion of the addition. And the obtained deposit is melt | dissolved in a solvent, Magnesium sulfate is added and spin-dry | dehydrated, It filters after that, A solvent is removed and the refined acrylic polymer is obtained.

  The polymerizable monomer having a polymerizable unsaturated bond as component (B) has at least one unsaturated bond (unsaturated double bond) polymerized by heat or light in one molecule, preferably a silicon atom. And a monomer having no siloxane structure in which oxygen atoms are alternately bonded. The unsaturated bond is preferably introduced into the component (B) as a (meth) acrylate group. This polymerizable monomer preferably does not have an ether structure from the viewpoint of heat resistance. From the viewpoint of light resistance, the number of aromatic rings is preferably 1 or less.

  Specific examples of the polymerizable monomer (B) include glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate glycidyl ether, and methyl (meth) acrylate. , Ethyl (meth) acrylate, n-propyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, ethylhexyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) ) Acrylate, ethoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate 2-methoxyethoxy (meth) acrylate, 2-ethoxyethoxy (meth) acrylate, pyrenoxide adduct (meth) acrylate, octafluoropentyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, mono (meth) acrylate having cyclohexyl mono (meth) acrylate and tricyclodecane, (meth) acrylate; ethylene glycol di (meth) acrylate, methanediol di (meth) acrylate, 1, 2-ethanediol di (meth) acrylate, 1,3-butanediol di (meth) acrylate, 1,3-propanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,5- Bae Tandiol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,7-heptanediol di (meth) acrylate, 1,8-octanediol di (meth) acrylate, 1,9-nonanediol di ( (Meth) acrylate, 1,10-decanediol di (meth) acrylate, 2-butyl-2-ethyl-1,3-propanediol di (meth) acrylate, 3-methyl-1,5-pentanediol di (meth) ) Acrylate, neopentyl di (meth) acrylate, dimethylol tricyclodecane di (meth) acrylate, zinc di (meth) acrylate, 2- (meth) acryloyloxyethyl acid phosphate, caprolactone modified tricyclodecane dimethanol di (meth) Acrylate, one end (meth) Acrylic modified silicone oil and both terminal (meth) acrylic modified silicone oil are mentioned. These are used alone or in combination of two or more.

  As the radical polymerization initiator of component (C), a radical thermal polymerization initiator that generates radicals by heat or a photopolymerization initiator that generates radicals by light is used.

  As the radical thermal polymerization initiator, any one that can be used for ordinary radical polymerization, such as an azo initiator and a peroxide initiator, can be used. Examples of azo initiators are azobisisobutyronitrile, azobis-4-methoxy-2,4-dimethylvaleronitrile, azobiscyclohexanone-1-carbonitrile and azodibenzoyl. Examples of peroxide initiators include benzoyl peroxide, lauroyl peroxide, di-t-butylperoxyhexahydroterephthalate, t-butylperoxy-2-ethylhexanoate, 1,1-t-butylperoxy -3,3,5-trimethylcyclohexane, t-butylperoxyisopropyl carbonate and di-t-hexyl peroxide.

  Since the crosslinking reaction of the resin composition according to this embodiment tends to be relatively difficult to proceed, it is effective to use a plurality of radical thermal polymerization initiators having different half-life temperatures in combination in order to advance the reaction more efficiently. It is. For example, when lauroyl peroxide and t-butylperoxyisopropyl carbonate are used in combination, the crosslinking reaction proceeds mainly by the action of lauroyl peroxide at 60 ° C. for 5 hours, and then heated at 120 ° C. for 1 hour. -Crosslinking reaction can be advanced by the action of butylperoxyisopropyl carbonate.

  The photopolymerization initiator is not particularly specified as long as it efficiently absorbs and activates ultraviolet rays from an industrial UV irradiation apparatus, but is preferably one that does not yellow the cured product. Specific examples of the photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-1,2-diphenylethane-1-one, 2-hydroxy-methyl-1-phenyl-propan-1-one, Oligo (2-hydroxy-2-methyl-1- (4- (1-methylvinyl) phenyl) propanone, oligo (2-hydroxy-2-methyl-1- (4- (1-methylvinyl) phenyl) propanone and Mixtures with tripropylene glycol diacrylate and oxy-phenyl-acetic acid 2- (2-oxo-2-phenyl-acetoxy-ethoxy) -ethyl ester and oxy-phenyl-acetic acid 2- (2-hydroxy- Mention may be made of mixtures of ethoxy) -ethyl esters.

  The amount of component (B) in the resin composition is preferably 10 to 70 parts by weight, more preferably 20 to 60 parts by weight, based on 100 parts by weight of component (A). If it is less than 10 parts by weight, the viscosity of the resin composition tends to be too high and difficult to handle, and if it is more than 70 parts by weight, the bending strength of the cured product tends to decrease.

  The amount of component (C) in the resin composition is preferably 0.01 to 5 parts by weight, preferably 0.1 to 1 part by weight based on 100 parts by weight of the total amount of components (A) and (B). More preferably, it is a part. If the blending amount exceeds 5 parts by weight, the cured product tends to be colored by heat or near-ultraviolet rays compared to the case of less than 5 parts by weight, and if it is less than 0.01 part by weight, curing is efficiently performed. It tends to be difficult to progress. When a plurality of thermal radical polymerization initiators having different half-life temperatures are used in combination, the total blending amount is preferably within the above range.

  The resin composition may contain other components as required in addition to the components (A), (B) and (C). For example, a hindered amine-based light stabilizer, a phenol-based or phosphorus-based antioxidant, an ultraviolet absorber, an inorganic filler, an organic filler, a coupling agent, and a polymerization inhibitor can be added to the resin composition. From the viewpoint of moldability, a mold release agent, a plasticizer, an antistatic agent, a flame retardant, and the like may be added to the resin composition.

  The resin composition according to the present embodiment described above has high optical transparency of the cured product, and is excellent in heat resistance, light resistance, and mechanical properties. Cured products obtained by curing the resin composition include members used as transparent substrates, adhesives, lenses, or optical waveguides, and optical semiconductor elements such as light emitting diodes (LEDs), phototransistors, photodiodes, and solid-state imaging devices. It is used suitably for the optical member used as a transparent member.

  FIG. 1 is a schematic end view showing an embodiment of an optical semiconductor element provided with an optical member. The optical semiconductor element 100 shown in FIG. 1 is a light emitting diode called a chip type or a surface mount type. The optical semiconductor element 100 includes a light emitting diode element 2 and a transparent optical member 1 provided so as to seal the light emitting diode element 2. The light emitting diode element 2 is disposed at the bottom of the cavity 10 formed by the case member 5. The light emitting diode element 2 is electrically connected to the lead frame 7 a via the connection layer 20, and is electrically connected to the lead frame 7 b via the wire 8.

  The optical member 1 covers the light emitting diode element 2 and fills the cavity 10. The optical member 1 mainly protects the light-emitting diode element 2 from the outside air and mainly plays a role of supporting a phosphor.

  The optical member 1 is formed by, for example, a method of pouring the resin composition solution described above into the cavity 10 and curing the resin composition in the cavity 10 by heating or light irradiation. In order to inhibit curing and prevent coloring, it is desirable to reduce the oxygen concentration in the resin composition in advance by nitrogen bubbling.

  In the case of thermosetting, the temperature and time are appropriately adjusted according to the type, combination, addition amount and the like of the component (C) so that the curing is finally completed. Typically, curing is performed by heating at 60 to 150 ° C. for about 1 to 5 hours. In order to reduce the internal stress generated by the rapid curing reaction, it is desirable to raise the curing temperature stepwise.

  In the present embodiment, the outer surface S1 of the optical member 1 is flat, but the present invention is not limited to this. For example, the optical semiconductor element may be provided with a light condensing function by making the outer surface of the optical member into a concave lens shape or a convex lens shape.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

Synthetic production example 1 of acrylic polymer
101 parts by weight of toluene was placed in a reaction vessel, heated to 140 ° C. with stirring under a pressure of 0.15 MPa (1.5 kgf / cm ² ) under a nitrogen gas atmosphere. 114 parts by weight of the polymerizable monomer composition having the composition was uniformly dropped over 2 hours.

  After completion of the dropwise addition, the reaction was further allowed to proceed for 4 hours to synthesize a copolymer. The molar ratio of the obtained copolymer was (a) / (b) / (c) / (d) = 30/20/30/20, and the weight average molecular weight was 2000.

  Next, 10.3 parts by weight of acrylic acid, 1 part by weight of triphenylphosphine, and 0.3 parts by weight of hydroquinone monomethyl ether are added to 214 parts by weight of this copolymer, and 100% of the copolymer is blown in at atmospheric pressure while blowing air. The mixture was stirred at 0 ° C. for 10 hours to obtain a solution (solid content 50% by weight) of an acrylic polymer (acid value 1.5) having an acrylic group introduced as a side chain.

  Furthermore, this acrylic polymer solution was added dropwise to a 10-fold amount of a poor solvent (methanol: water = 50: 50) with stirring, allowed to stand for several hours, and then the supernatant was removed to obtain a precipitate. . The precipitate was dissolved in THF, dehydrated with magnesium sulfate, and filtered. The filtrate was desolvated using an evaporator until the toluene content was 1% by weight or less to obtain a purified acrylic polymer.

Production Examples 2 to 10
An acrylic polymer was obtained through the same steps as in Production Example 1 except that the composition of the polymerizable monomer composition was changed to the composition described in Table 1 below.

All the numerical units of the composition in Table 1 are parts by weight.
GMA: glycidyl methacrylate, light ester G, MMA: Methyl methacrylate, manufactured by Kyoeisha Chemical Co., Ltd. TM-0701T: 3-methacryloxypropyltris (trimethylsiloxy) silane, X-24- manufactured by Chisso Corporation 8201: One-end methacryl-modified silicone oil, perhexyl D manufactured by Shin-Etsu Chemical Co., Ltd .: di-t-hexyl peroxide, HEMA manufactured by Nippon Oil & Fats Co., Ltd .: 2-hydroxyethyl methacrylate, light ester HO, manufactured by Kyoeisha Chemical Co., Ltd.

Example 1
50 parts by weight of the acrylic polymer obtained in Production Example 1, 50 parts by weight of lauryl acrylate (Light acrylate LA, manufactured by Kyoeisha Chemical Co., Ltd.), 0.5 parts by weight of lauroyl peroxide (Perroyl L, manufactured by Nippon Oil & Fats Co., Ltd.) A resin composition was prepared by mixing 0.5 parts by weight of t-butyl peroxy-2-ethylhexanoate (Perbutyl I, manufactured by NOF Corporation) at room temperature.

  The resin composition was poured into a mold in which 3 mm and 1 mm thick silicone spacers were sandwiched between glass plates, and heated in an oven at 60 ° C. for 3 hours and 120 ° C. for 1 hour to obtain 3 mm and 1 mm thicknesses. A plate-like cured product was obtained.

Examples 2-11 and Comparative Examples 1-3
Using the acrylic polymer obtained from Production Examples 2 to 10, a resin composition having the composition shown in Table 2 below was prepared in the same manner as in Example 1, and 3 mm and 1 mm thick plates were prepared using the resin composition. A cured product was obtained.

All numerical units of the composition in Table 2 are parts by weight.
LA: lauryl acrylate, NK ester LA, Shin Nakamura Chemical Co., Ltd. MMA: methyl methacrylate, light ester M, Kyoeisha Chemical Co., Ltd. 1,6HXA: 1,6 hexanediol diacrylate, light acrylate 1,6HX-A, Kyoeisha Chemical Co., Ltd. LPO: Lauroyl peroxide, Parroyl L, Nippon Oil & Fat Co., Ltd. PBI: t-Butylperoxy-2-ethylhexanoate, Perbutyl I, Nippon Oil & Fat Co., Ltd.

Evaluation of hardened | cured material The mechanical characteristic and optical characteristic of the hardened | cured material obtained by each Example and each comparative example were measured by the method shown below.

Bending test A test piece having a size of 20 × 50 mm was cut out from a 3 mm thick plate-like cured product, and a bending test was conducted by a three-point support in accordance with JIS-K-6911 using a three-point bending test apparatus. The bending strength was calculated from I). The distance between fulcrums was 24 mm, the crosshead moving speed was 0.5 mm / min, and the measurement temperature was room temperature (25 ° C.) and 250 ° C., which is close to the reflow temperature when mounting a semiconductor package.

In the above formula, σfB: bending strength (MPa), P ′: breaking load or maximum load (N), L: distance between fulcrums, W: width of test piece, h: thickness of test piece.
Package mounting reliability

  A package including a cured product formed using the resin composition of each example and comparative example as an optical member was produced. The package was loaded with 100 cycles of a cold temperature cycle in which -40 ° C / 30 minutes and 85 ° C / 30 minutes were one cycle. The presence or absence of defects such as cracks and delamination of the optical member in the package in the initial (0 cycle) and 100 cycles was confirmed. Several packages were evaluated and the number of defective products with defects was confirmed. Then, a defective product rate (= (number of defects / number of packages subjected to test) × 100) (%) was calculated, and the numerical value was used as an index of mounting reliability.

Transmittance, yellowing degree The transmission spectrum of a 1 mm thick test piece was measured using a spectrophotometer, and the transmittance at 400 nm was determined. Further, tristimulus values X, Y and Z in the case of the standard light C were obtained from the obtained transmission spectrum, and the yellowing degree (YI) was calculated by the following formula. The transmittance and yellowing degree were measured not only after curing (initial stage) but also for a test piece after heating at 150 ° C. for 72 hours (after high temperature standing) as an evaluation of heat discoloration.

  The evaluation results are summarized in Table 3. In the bending strength shown in Table 3, the numerical value represented by using an inequality sign indicates the strength value calculated based on the maximum load value because the test piece did not break. As shown in Table 3, it is clear that the cured products of Examples 1 to 11 do not break at room temperature in the bending test, have excellent mechanical properties (flexibility), and excellent mounting reliability. . Further, it is clear that the examples have a high initial transmittance and a small yellowing degree, a small decrease in the transmittance after being left at a high temperature, and a small change in the yellowing degree.

  On the other hand, when an acrylic polymer containing no component (d) is used as in Comparative Example 1, it is clear that the mounting reliability is inferior to that of the Example. Further, even when an acrylic polymer containing no siloxane structure is used as in Comparative Example 2, it is apparent that both flexibility and colorability are inferior.

It is a schematic end view which shows one Embodiment of the optical semiconductor element provided with the optical member.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Optical member, 2 ... Light emitting diode element, 5 ... Case member, 7a, 7b ... Lead frame, 8 ... Wire, 10 ... Cavity, 100 ... Optical semiconductor element.

Claims (7)

(A) (a) an epoxy group-containing (meth) acrylate, (b) a non-silicone polymerizable monomer having one polymerizable unsaturated bond, (c) a siloxane structure-containing (meth) acrylate, and (d) An acrylic polymer obtained by reacting an unsaturated carboxylic acid with at least a part of an epoxy group in a copolymer in which a monomer containing a hydroxyl group-containing (meth) acrylate is copolymerized;
(B) a polymerizable monomer having a polymerizable unsaturated bond;
(C) a resin composition containing a radical polymerization initiator.   The copolymer is based on the total monomer units in the copolymer, (a) 10 to 65 mol% of an epoxy group-containing (meth) acrylate, and (b) 20 to 75 mol% of a polymerizable monomer. (C) A copolymer copolymerized at a copolymerization ratio of 10 to 65 mol% of a siloxane structure-containing (meth) acrylate and (d) 5 to 60 mol% of a hydroxyl group-containing (meth) acrylate. Resin composition.   The equivalent ratio of the carboxyl group of the unsaturated carboxylic acid reacted with respect to the epoxy group in the copolymer is 0.95 to 1.1 with respect to the equivalent of the epoxy group in the copolymer. 3. The resin composition according to 1 or 2.   The resin composition as described in any one of Claims 1-3 whose (a) epoxy-group-containing (meth) acrylate is glycidyl (meth) acrylate. (C) Resin composition as described in any one of Claims 1-4 whose siloxane structure containing (meth) acrylate is a compound represented by following General formula (1).

[Wherein n ¹ represents an integer of 0 to 10, n ² represents an integer of 0 to 150, and R ¹ represents a hydrogen atom, an alkyl group having 1 to 9 carbon atoms, an aryl group or a trialkylsilyloxy group. And a plurality of R ¹ in the same molecule may be the same or different, and R ² represents a hydrogen atom or a methyl group. ] (D) The resin composition according to any one of claims 1 to 5, wherein the hydroxyl group-containing (meth) acrylate is a compound represented by the following general formula (2a) or (2b).

[In Formula (2a), m ¹ represents an integer of 0 to 20, and R ³ represents a hydrogen atom or a methyl group. ]

[In Formula (2b), m ² and m ³ each independently represents an integer of 0 to 20, and R ⁴ represents a hydrogen atom or a methyl group. ]   The optical member which consists of hardened | cured material which hardened | cured the resin composition as described in any one of Claims 1-6.

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