JP5840611B2 - Curable composition and cured product thereof - Google Patents

Description

  The present invention relates to a curable composition, a cured product thereof, and an optical member. More specifically, a curable composition that has a low viscosity before being cured and can be rapidly cured by heating to form a cured product having excellent optical properties and environmental resistance, and the curable composition The present invention relates to a cured resin obtained by curing and an optical member such as a lens made of the cured resin.

  Curable resin compositions are used as plastic materials in machine part materials, electrical / electronic parts materials, automobile parts materials, civil engineering and building materials, molding materials, paints, adhesives, sealing materials, etc. It is also attracting attention as a material for optical members.

  As a curable composition for forming a low Abbe number lens, a curable composition mainly composed of a (meth) acrylic acid ester having a fluorene ring is known (Patent Document 1). However, this curable composition cannot form a lens having a sufficiently low Abbe number, and it cannot be said that the heat resistance is sufficient, and when exposed to high temperatures, the shape changes or the light transmittance decreases significantly. It was a problem to do.

  In addition, it is known that (meth) acrylic acid ester having a fluorene ring has high viscosity and poor fluidity, and Patent Document 2 discloses a (meth) acrylic acid ester having a fluorene ring to a naphthalene ring, an anthracene ring, Or the method of improving fluidity | liquidity by using together the (meth) acrylate which has an anthrone ring is described. However, (meth) acrylates having a naphthalene ring, anthracene ring, or anthrone ring are not so low in viscosity and need to be added in a large amount in order to ensure appropriate fluidity. For this reason, adding an amount capable of sufficiently securing fluidity impairs optical properties, and it is difficult to combine fluidity and optical properties.

  Therefore, it is difficult to apply the casting molding method in which the curable composition is applied to the mold and then cured and molded because sufficient fluidity cannot be obtained, and a molding method by injection molding is adopted. It was. However, in the injection molding method, the flow passage portion (runner) that guides the resin to the mold is discarded without being used, but there is a lot of discarded resin, and excess resin protrudes from the gap between the molds. Because burrs are formed, it takes extra time to remove burrs, and if the strength of burrs is weak, broken burrs may be mixed into other products when the mold is removed. In many cases, the method of increasing the strength by increasing the “burr” portion is employed, and therefore, the utilization rate of the resin is low, which is uneconomical. In addition, the press molding method frequently used for thermoplastic resins and the like requires pretreatment such as pre-curing when molding a curable composition, and general resins are molding methods with excellent productivity. However, as a method for forming a member that requires high heat resistance, it has become a rather complicated method.

  In addition, thermoplastic resins such as polyolefins and engineering plastics have a problem of yellowing due to heating during molding and use of molded products for a long period of time. As a method for suppressing yellowing, a method of adding an antioxidant is known (Non-Patent Document 1). The antioxidant includes a radical scavenger that traps and invalidates the generated radicals, and a peroxide decomposer that decomposes the generated peroxide into an inactive substance and suppresses the generation of new radicals. There are two types, and as radical scavengers, hindered phenol compounds, hindered amine compounds, and peroxide decomposers are mainly used phosphorus compounds (Patent Document 3).

  However, since the radical scavenger has an action of inhibiting radical polymerization, if a sufficient amount is added to exert the yellowing suppression effect, the curing of the curable composition itself does not proceed, and the resulting cured resin There was a problem that toughness decreased. Phosphorus compounds have a small effect on suppressing yellowing, and it is difficult to sufficiently suppress yellowing under high temperature conditions (for example, about 260 ° C.) such as soldering by a reflow method. When used as a material for members, the yellowing suppression effect was quite insufficient. Therefore, for example, most camera-equipped mobile phones are manufactured through a process of connecting a separately manufactured camera module with a connector after a soldering process (mounting process) by a reflow method, and the manufacturing process becomes complicated. It was.

JP 2009-235196 A JP 2010-37470 A Special table 2008-52497 gazette

Tobita Ikuo, “Analysis of Causes of Discoloration and Coloring Problems in Polymer Materials and Their Countermeasures Collection”, Chapter 3, Technical Information Association (2009)

  Therefore, the object of the present invention is low viscosity before curing, cures quickly by heating, exhibits a low Abbe number of 30 or less, is excellent in transparency and heat resistance, and is soldered by a reflow method. Provided are a curable composition capable of forming a curable resin that does not easily yellow even under high temperature conditions such as attaching, a curable resin obtained by curing the curable composition, and an optical member made of the curable resin. There is.

  As a result of intensive studies to solve the above problems, the present inventors have two (meth) acryloyloxy groups in the molecule that are extremely high in viscosity but excellent in optical properties and heat resistance, and When a specific amount of a compound having at least one vinyl group or (meth) acryloyloxy group in the molecule and not having a fluorene ring is added to the (meth) acrylic acid ester having a fluorene ring, the optical properties are maintained. It has been found that the fluidity can be improved by significantly reducing the viscosity. Furthermore, it has been found that by adding a thiol compound, it is possible to form a cured resin that does not easily turn yellow even under high temperature conditions such as soldering by a reflow method. The present invention has been completed based on these findings.

（式中、環Ｚ¹、Ｚ²は同一又は異なって、芳香族炭素環を示す。Ｒ¹、Ｒ³は同一又は異なって、アルキレン基を示し、Ｒ²、Ｒ⁴は同一又は異なって、水素原子又はメチル基を示す。ｎ¹、ｎ²は同一又は異なって、０以上の整数を示す）
で表される、分子内に２個の（メタ）アクリロイルオキシ基を有し、且つ、フルオレン環を有する化合物
成分（Ｂ）：分子内にビニル基若しくは（メタ）アクリロイルオキシ基を少なくとも１つ有し、且つ、フルオレン環を有しない化合物That is, the present invention is characterized in that the following component (A) and component (B) are contained at a blending ratio [the former / the latter (weight ratio)] of 70/30 to 99/1 and a thiol compound. A curable composition is provided.
Component (A): Formula (1) below

(In the formula, rings Z ¹ and Z ² are the same or different and each represents an aromatic carbocycle. R ¹ and R ³ are the same or different and each represents an alkylene group; R ² and R ⁴ are the same or different; A hydrogen atom or a methyl group, n ¹ and n ² are the same or different and represent an integer of 0 or more)
A compound having two (meth) acryloyloxy groups in the molecule and having a fluorene ring Component (B): having at least one vinyl group or (meth) acryloyloxy group in the molecule And a compound having no fluorene ring

（式中、Ｘは１価又は２価の脂肪族炭化水素基、脂環式炭化水素基、単環式芳香族炭化水素基又はこれらの基が結合した基を示す。Ｒ⁵はアルキレン基を示し、Ｒ⁶は水素原子又はメチル基を示す。ｎ³は０以上の整数を示し、ｎ⁴は０又は１を示し、ｎ⁵は１又は２を示す）
で表される化合物が好ましい。As the component (B), the following formula (2)

(In the formula, X represents a monovalent or divalent aliphatic hydrocarbon group, alicyclic hydrocarbon group, monocyclic aromatic hydrocarbon group or a group to which these groups are bonded. R ⁵ represents an alkylene group. R ⁶ represents a hydrogen atom or a methyl group, n ³ represents an integer of 0 or more, n ⁴ represents 0 or 1, and n ⁵ represents 1 or 2.
The compound represented by these is preferable.

  The viscosity at 25 ° C. is preferably 3600 mPa · s or less.

  The boiling point of the thiol compound is preferably 100 ° C. or higher, and the thiol compound is preferably a linear or branched alkanethiol or a linear or branched alkanedithiol.

  The curable composition is preferably thermosetting.

  The present invention also provides a cured resin obtained by curing the curable composition.

  The present invention still further provides an optical member made of the cured resin.

  According to the curable composition of the present invention, since it is excellent in fluidity before being cured, it is easy to uniformly apply to a mold while suppressing the generation of bubbles, and the workability is excellent. Moreover, since it can harden rapidly by heating, the metal metal mold | die which an elaborate work is easy can be used as a metal mold | die, and the shape of a metal mold | die can be reproduced with high precision. Therefore, a member having a desired shape such as a fine structure can be accurately and efficiently obtained by a casting molding method or the like. For example, a large number of members can be obtained at a time using one mold.

  The cured resin thus obtained has an Abbe number of 30 or less, is excellent in transparency and heat resistance, and has a yellowing suppression effect that hardly causes yellowing even at a high temperature of about 260 ° C. Since the cured resin according to the present invention has the above characteristics, it is particularly suitable for the use of optical members such as lenses. For example, when a lens made of a cured resin obtained by curing the curable composition of the present invention is used as a lens for a camera-equipped mobile phone, the camera module can be simultaneously mounted in a soldering process (mounting process) by a reflow method. It becomes possible, and the connection process of the camera module by the connector performed after the soldering process can be omitted.

  The curable composition according to the present invention contains the following component (A) and component (B) as a curable monomer in a ratio of 70/30 to 99/1 in a compounding ratio [the former / the latter (weight ratio)] And a thiol compound.

[Component (A)]
Component (A) in the present invention is a curable monomer represented by the above formula (1), having two (meth) acryloyloxy groups in the molecule, and having a fluorene ring. In formula (1), the rings Z ¹ and Z ² are the same or different and represent an aromatic carbocyclic ring. R ¹ and R ³ are the same or different and represent an alkylene group, and R ² and R ⁴ are the same or different and represent a hydrogen atom or a methyl group. n ¹ and n ² are the same or different and represent an integer of 0 or more. The fluorene ring, ring Z ¹ and ring Z ² may have a substituent.

Examples of the aromatic carbocycle in ring Z ¹ and ring Z ² include about 1 to 4 aromatic carbocycles such as a benzene ring, a naphthalene ring, and an anthracene ring. Preferred aromatic carbocycles include benzene rings, naphthalene rings and the like.

As an alkylene group in R < ¹ >, R < ³ >, C1-C10 linear or branched alkylene groups, such as a methylene, ethylene, propylene, trimethylene, tetramethylene, a hexamethylene group, are mentioned, for example. Preferred alkylene groups include C2-C6 alkylene groups (particularly C2-C3 alkylene groups) such as ethylene, propylene and trimethylene groups.

Each of n ¹ and n ² is an integer of 0 or more, preferably an integer of 0 to 4, and preferably an integer of 1 to 4 in terms of lower viscosity and excellent fluidity.

Examples of the substituent that the fluorene ring and ring Z ¹ and ring Z ² may have include alkyl groups such as methyl, ethyl, propyl and isopropyl groups (for example, C _1-6 alkyl groups, preferably methyl Group); cycloalkyl groups such as cyclopentyl and cyclohexyl groups (for example, C _5-8 cycloalkyl groups); aryl groups such as phenyl and naphthyl groups (for example, C _6-15 aryl groups); aralkyl groups such as benzyl groups ( For example, C _7-16 aralkyl group); acyl group such as acetyl, propionyl, benzoyl group (eg, C _1-10 acyl group); alkoxy group such as methoxy, ethoxy, propyloxy, isopropyloxy group (eg, C _{1 -6} alkoxy group); methoxycarbonyl, alkoxycarbonyl groups such as ethoxycarbonyl group (e.g., C _1-4 alkoxy - carbonyl group Cyano group; a carboxyl group; a nitro group; an amino group; a substituted amino group (e.g., di-C _1-4 alkylamino group, etc.); fluorine atom, it may be mentioned a halogen atom such as a chlorine atom.

Typical examples of the compound represented by formula (1) in the present invention having two (meth) acryloyloxy groups in the molecule and having a fluorene ring include the following compounds. it can. These can be used alone or in admixture of two or more.

  The ratio of the sum of the components (A) in the curable composition is 50 to 99% by weight, preferably 55 to 80% by weight of the entire curable monomer, although it varies depending on the use of the curable resin. When the ratio of the sum total of the component (A) in a curable composition exceeds the said range, the fluidity | liquidity of a curable composition will fall remarkably and there exists a tendency for workability | operativity to fall. In addition, the resulting cured resin is likely to have a pulse. On the other hand, when the ratio of the sum total of the component (A) in a curable composition is less than the said range, there exists a tendency for heat resistance to fall.

[Component (B)]
In the curable composition according to the present invention, the component (B) in the present invention contains 50% by weight or more of the above-described component (A) having a high viscosity, thereby improving the fluidity of the curable composition. A curable monomer having at least one vinyl group or (meth) acryloyloxy group in the molecule and having no fluorene ring.

As a component (B) in this invention, the compound represented by the said Formula (2) is preferable. In formula (2), X is a monovalent or divalent aliphatic hydrocarbon group, alicyclic hydrocarbon group, monocyclic aromatic hydrocarbon group, or a group to which these groups are bonded. R ⁵ represents an alkylene group, and R ⁶ represents a hydrogen atom or a methyl group. n ³ represents an integer of 0 or more, n ⁴ represents 0 or 1, and n ⁵ represents 1 or 2.

  Examples of the monovalent aliphatic hydrocarbon group for X include 1 to 20 carbon atoms such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, s-butyl, t-butyl, pentyl, hexyl, decyl, and dodecyl groups. (Preferably 1 to 10, more preferably 1 to 3) alkyl group; vinyl, allyl, 1-butenyl group and the like having about 2 to 20 carbon atoms (preferably 2 to 10 and more preferably 2 to 3) Alkenyl groups; alkynyl groups having about 2 to 20 carbon atoms (preferably 2 to 10, more preferably 2 to 3) such as ethynyl and propynyl groups can be exemplified.

Examples of the monovalent alicyclic hydrocarbon group in X include 3 to 20 members (preferably 3 to 15 members, more preferably 5 to 8 members) such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and cyclooctyl groups. A cycloalkenyl group of about 3 to 20 members (preferably 3 to 15 members, more preferably 5 to 8 members) such as cyclopentenyl and cyclohexenyl groups; a perhydronaphthalen-1-yl group, Norbornyl, adamantyl, bicyclo [3.3.0] octyl, tricyclo [5.2.1.0 ^2,6 ] decalyl, tricyclo [6.2.1.0 ^2,7 ] undecalyl, tetracyclo [4 4.0.1, ^2,5 . And a bridged cyclic hydrocarbon group such as 1 ^7,10 ] dodecan-3-yl group.

  Examples of the monovalent monocyclic aromatic hydrocarbon group for X include aromatic hydrocarbon groups other than the condensed polycyclic aromatic hydrocarbon group such as a phenyl group and a 4-biphenyl group.

  Examples of the divalent aliphatic hydrocarbon group, alicyclic hydrocarbon group, and monocyclic aromatic hydrocarbon group in X include the monovalent aliphatic hydrocarbon group, alicyclic hydrocarbon group, and A corresponding group obtained by removing one hydrogen atom from a monocyclic aromatic hydrocarbon group can be exemplified.

  As a group to which a monovalent or divalent aliphatic hydrocarbon group, an alicyclic hydrocarbon group, or a monocyclic aromatic hydrocarbon group is bonded, two or more monovalent or divalent aliphatic hydrocarbon groups, Examples thereof include a group formed by bonding an alicyclic hydrocarbon group or a monocyclic aromatic hydrocarbon group via a single bond or a linking group.

  Examples of the linking group include a carbonyl group (—CO—), an ether bond (—O—), an ester bond (—COO—), an amide bond (—CONH—), a carbonate bond (—OCOO—), and these. And a group in which a plurality of are bonded.

  The monovalent or divalent aliphatic hydrocarbon group, alicyclic hydrocarbon group, monocyclic aromatic hydrocarbon group, or the group hydrocarbon group to which these groups are bonded may be various substituents such as halogen atoms. , Oxo group, hydroxyl group, substituted oxy group (for example, alkoxy group, aryloxy group, aralkyloxy group, acyloxy group, etc.), carboxyl group, substituted oxycarbonyl group (alkoxycarbonyl group, aryloxycarbonyl group, aralkyloxycarbonyl group) Etc.), a substituted or unsubstituted carbamoyl group, a cyano group, a nitro group, an acyl group, a substituted or unsubstituted amino group, a sulfo group, a heterocyclic group and the like. The hydroxyl group and carboxyl group may be protected with a protective group commonly used in the field of organic synthesis. Furthermore, a non-aromatic heterocycle may be condensed with a ring of an alicyclic hydrocarbon group or an aromatic hydrocarbon group.

R ⁵ in Formula (2) represents an alkylene group, and examples thereof include linear or branched alkylene groups having 1 to 10 carbon atoms such as methylene, ethylene, propylene, trimethylene, tetramethylene, and hexamethylene groups. . Preferred alkylene groups include linear or branched alkylene groups having 2 to 6 carbon atoms such as ethylene, propylene, and trimethylene groups (particularly linear or branched alkylene groups having 2 to 3 carbon atoms). Is included.

n ³ represents an integer of 0 or more, preferably an integer of 0 to 10, more preferably an integer of 0 to 4. n ⁵ represents 1 or 2. In the case where n ⁵ is 1, compared to the case where n ⁵ is 2, the ratio of the crosslinking points in the entire resin composition is reduced so that the curing shrinkage is reduced, so that the flexibility of the resulting cured resin is increased, Generation | occurrence | production of pulse separation on this cured resin surface can be suppressed, and the outstanding transparency can be maintained. In the present invention, pulsation means an optically inhomogeneous state on the surface of the cured resin, and refers to a phenomenon in which wrinkles, fluctuations, irregularities and the like are observed on the surface of the cured resin.

  The viscosity at 25 ° C. of the component (B) in the present invention is preferably about 300 mPa · s or less, particularly 100 to 200 mPa · s, particularly preferably 100 to 150 mPa · s. When the viscosity at 25 ° C. exceeds the above range, it tends to be difficult to improve the fluidity of the curable composition with a small amount of addition, and the fluidity is easy to work while maintaining optical properties in the curable composition. It tends to be difficult to impart the.

The following compounds can be mentioned as a typical example of a component (B).

In particular, the component (B) in the present invention is excellent in economic efficiency and maintains excellent optical properties (particularly, a low Abbe number, transparency, and refractive index) by being contained in the curable composition. However, the compound in which X in the formula (2) is a monovalent or divalent monocyclic aromatic hydrocarbon group is preferable in that the fluidity can be improved while suppressing the occurrence of pulse separation. X in the formula (2) represented by the above formulas (2b), (2c), (2d), (2p) is a monovalent monocyclic aromatic hydrocarbon group, and , Compounds wherein n ⁵ is 1 are preferred. These can be used alone or in admixture of two or more.

  The ratio of the sum of the components (B) in the curable composition varies depending on the use of the curable resin, but is 1 to 30% by weight of the entire curable monomer, preferably 5 to 25% by weight, and most preferably Is 5 to 20% by weight. Moreover, the compounding ratio [the former / the latter (weight ratio)] of the component (A) and the component (B) in the curable composition is 70/30 to 99/1, preferably 75/25 to 95/5. Most preferably, it is 80/20 to 95/5. When the ratio of the sum total of the component (B) in a curable composition exceeds the said range, it will become difficult to maintain the outstanding optical characteristic, and there exists a tendency for heat resistance to fall. On the other hand, when the ratio of the sum total of the component (B) in a curable composition is less than the said range, the fluidity | liquidity of a curable composition will fall remarkably and there exists a tendency for workability | operativity to fall. In addition, the resulting cured resin is likely to have a pulse.

[Thiol compound]
In this invention, a thiol compound is mix | blended in a curable composition, It is characterized by the above-mentioned. The thiol compound includes a monothiol compound and a dithiol compound.

  When a cured resin of a radically polymerizable compound having an aromatic ring is placed at a high temperature, radicals are generated in the polymer chain forming the cured resin by the generated peroxide. It is considered that this radical pulls out a hydrogen atom of the polymer chain to form a conjugated unsaturated bond, and yellowing occurs due to the formation of the conjugated unsaturated bond.

  Since the curable composition in the present invention contains a thiol together with a radical polymerizable compound having an aromatic ring, the thiol compound captures a peroxide generated at a high temperature, and a conjugated unsaturated bond formed on the polymer chain. It is presumed that the yellowing of the resin at high temperatures can be effectively suppressed because it has a function of eliminating the conjugated unsaturated bond through an enethiol reaction. The radical generated from the thiol compound is an electron-withdrawing radical, and the radical species involved in radical curing polymerization are also electron-withdrawing radicals. In general, the chain transfer ability between electron-withdrawing radicals is not high, so unlike the case of using a phenolic antioxidant as a yellowing inhibitor, it is assumed that inhibition of radical curing polymerization is prevented. Is done. Thereby, the curable composition according to the present invention is cured at a high curing rate, has excellent yellowing resistance, and suppresses the degree of yellowing to a very low level even when exposed to a high temperature of about 260 ° C., for example. A cured resin that can be formed can be formed.

  As a thiol compound, there is no volatilization or foaming when the curable composition is crosslinked and cured, and even if it is exposed to high temperature conditions in a cured resin (for example, in the reflow process) Heating) Those which are difficult to volatilize or foam are preferable, for example, those having a boiling point of 100 ° C. or higher, particularly those having a boiling point of 150 ° C. or higher, particularly those having a boiling point of 180 ° C. or higher. In the present specification, the term “boiling point” simply means the boiling point at normal pressure.

  Further, as the thiol compound of the present invention, it is preferable to use a neutral thiol compound as compared with an acidic or alkaline thiol compound in that the reactivity with the component (A) is mild and the storage stability is excellent. .

  Moreover, the compatibility with the said component (A) and component (B) is high, and the thing from which a uniform curable composition is obtained is preferable at the point which can provide the optical characteristic excellent in the cured resin obtained.

  Examples of the thiol compound include 1-hexanethiol (boiling point 150 ° C.), 1-heptanethiol (boiling point 177 ° C.), 1-octanethiol (boiling point 200 ° C.), tert-octanethiol (boiling point 156 ° C.), 1-nonane. Thiol, 1-decanethiol (boiling point 241 ° C), 1-undecanethiol (boiling point 104 ° C / 3mmHg), 1-dodecanethiol (boiling point 143 ° C / 16mmHg), 1-tetradecanethiol (boiling point 310 ° C), 1-hexadecanethiol 1-octadecanethiol and the like, and straight chain or branched chain alkanethiol having about 6 to 30 carbon atoms (preferably about 6 to 20 carbon atoms) can be exemplified.

  Examples of the dithiol compound include 1,4-butanedithiol (boiling point 195 ° C.), 2,3-butanedithiol (boiling point 87 ° C./50 mmHg), 1,5-pentanedithiol (108 ° C./15 mmHg) 1,6-hexane. Dithiol (boiling point 237 ° C), 1,7-heptanedithiol, 1,8-octanedithiol, 1,9-nonanedithiol, 1,10-decanedithiol (boiling point 297 ° C), 1,12-dodecanedithiol, 1,14 -Linear or branched alkanedithiol having about 4 to 30 carbon atoms (preferably about 4 to 20 carbon atoms) such as tetradecanedithiol, 1,16-hexadecanedithiol, 1,18-octadecanedithiol, etc. Can do.

  Among these thiol compounds, linear alkanethiol or alkanedithiol having 10 to 15 carbon atoms such as decanethiol, dodecanethiol, and decanedithiol is preferable in that it can exhibit a more excellent yellowing suppression effect. In particular, decanethiol and decanedithiol are preferable.

  The amount of the thiol compound used can be appropriately adjusted within a range that does not impair the curability of the curable composition, and varies depending on the type of the thiol compound. It is about 10% by weight, preferably about 0.1 to 5% by weight, and more preferably about 0.5 to 3% by weight. When there is too much usage-amount of a thiol compound, there exists a tendency for the sclerosis | hardenability of a curable composition to fall or to produce pulse separation easily. On the other hand, if the amount of the thiol compound used is too small, the yellowing resistance of the cured resin tends to decrease.

[Other ingredients]
The curable composition of the present invention may contain a thermal radical polymerization initiator and other various additives depending on the use of the curable resin.

  Examples of the thermal radical polymerization initiator include organic peroxides such as hydroperoxides, dialkyl peroxides, peroxyesters, diacyl peroxides, peroxydicarbonates, peroxyketals, and ketone peroxides. An oxide etc. can be mentioned. Specific examples of these thermal polymerization initiators include 1,1-di (t-butylperoxy) cyclohexane, dibenzoyl peroxide, t-butyl perbenzoate, and the like. Of the thermal radical polymerization initiators, compounds such as azo radical polymerization initiators that generate gas components with the generation of radicals are not preferred because they leave bubbles in the cured resin.

  As the thermal radical polymerization initiator, for example, trade name “Perhexa C” [1,1-di (t-butylperoxy) cyclohexane, manufactured by NOF Corporation], trade name “Perroyl L” [dilauroyl peroxide] Commercial products such as NOF Corporation] can be used.

  As a compounding quantity of a thermal radical polymerization initiator, it is about 0.1 to 10 weight% with respect to the whole curable composition, Preferably it is about 0.1 to 5 weight%.

  Other additives include, for example, curable monomers other than the above components (A) and (B), organosiloxane compounds, metal oxide particles, rubber particles, silicone-based and fluorine-based antifoaming agents, and silane coupling agents. , Fillers, plasticizers, leveling agents, antistatic agents, mold release agents, flame retardants, colorants, antioxidants, ultraviolet absorbers, ion adsorbers, pigments and the like. The compounding quantity of these various additives is 5 weight% or less with respect to the whole curable composition, for example. The curable composition of the present invention may contain a solvent, but if it is too much, bubbles may be formed in the cured resin. Therefore, it is preferably 10% by weight or less, particularly 1% by weight based on the entire curable composition. It is as follows.

  The curable composition of the present invention includes, for example, a predetermined amount of component (A), component (B), and thiol compound, and if necessary, a thermal radical polymerization initiator, various additives, and the like. Accordingly, it is prepared by stirring and mixing while excluding bubbles under vacuum. The temperature at the time of stirring and mixing is, for example, about 10 to 60 ° C. For the stirring / mixing, a known apparatus such as a rotation / revolution mixer, a single-screw or multi-screw extruder, a planetary mixer, a kneader, or a dissolver can be used.

  The viscosity at 25 ° C. of the curable composition according to the present invention is 3600 mPa · s or less, preferably 2000 mPa · s or less, more preferably 1500 mPa · s or less, and particularly preferably 1000 mPa · s or less. When the viscosity exceeds the above range, the fluidity is lowered and bubbles are likely to remain, and the casting property to the mold is lowered due to a decrease in coating property and filling property, and an increase in injection pressure. For this reason, it takes time to adjust the handling temperature, defoaming, and curing conditions (curing temperature, curing time, heating rate, cooling rate, etc.). Sex is reduced.

  The curable composition prepared by the above method can be molded by a conventionally known molding method such as a casting method or an injection molding method, and then promotes a radical polymerization reaction by heating to obtain a cured resin. . As heating conditions, the heating temperature is about 80 to 200 ° C. (preferably about 110 to 160 ° C.), and the heating time is about 1 to 5 minutes (preferably about 1 to 3 minutes). The curable composition according to the present invention has fast curability and can form a cured resin very quickly by heating under the above heating conditions. The curing rate of the cured resin according to the present invention measured by the DSC method is, for example, preferably 70% or more (preferably 80% or more) at 150 ° C. for 5 minutes. It is preferably 70% or more (preferably 80% or more) per minute. In addition, after taking out cured resin from a metal mold | die, you may post-cure (bake).

  Since the curable composition concerning this invention is excellent in fluidity | liquidity, it can be used suitably especially for the casting method. Therefore, the curable composition can be used efficiently as compared with the case of the injection molding method, and it is economical, and a cured resin having a desired shape can be produced speedily.

  Furthermore, since the curable composition concerning this invention is thermosetting, a metal metal mold | die can be used in the case of shaping | molding. A metal mold can be easily finer and finer than a glass mold or the like. Therefore, according to the curable composition of the present invention, a cured resin having a minute and dense shape can be easily formed.

  The cured resin of the present invention obtained by the above method is excellent in transparency. For example, for a cured resin having a thickness of 0.5 mm, the internal transmittance (%) at 400 nm is 90% or more, preferably 95% or more, particularly preferably. 98% or more.

The cured resin of the present invention is excellent in yellowing resistance. For example, the yellowing rate after a heat resistance test is 2% or less, preferably 1.5% or less, particularly preferably 0.5% or less for a cured resin having a thickness of 0.5 mm. Is 1.0% or less. In addition, the yellowing rate in this invention is represented by the decreasing degree of the internal transmittance in 400 nm before and behind the following heat resistance test, and is calculated | required by the following formula.
Heat resistance test: Repeated heat resistance test based on the reflow temperature profile described in JEDEC standard three times using 0.5mm thick cured resin using a table reflow oven manufactured by Shinapec Inc. Yellowing rate (%) = {(Internal transmittance before heat resistance test)-(Internal transmittance after heat resistance test)} / (Internal transmittance before heat resistance test) × 100

  Furthermore, the cured resin of the present invention is excellent in heat resistance, and for example, has a glass transition temperature of 100 ° C. or higher, preferably 110 to 170 ° C.

  The Abbe number of the cured resin of the present invention is 30 or less, preferably 28 or less, particularly preferably 27 or less. The refractive index of the lens varies depending on the wavelength of light, and a phenomenon (chromatic aberration) that causes a shift (bleed or blur) in the image occurs. In order to reduce the influence of this chromatic aberration, a normal lens has a structure that corrects chromatic aberration by combining a lens resin having a high Abbe number and a lens resin having a low Abbe number. The glass of a lens used in a camera is classified into two types according to the Abbe number. Generally, those having an Abbe number of 50 or less are called flint glass, and those having 50 or more are called crown glass. The cured resin of the present invention can be suitably used as a low Abbe number lens resin.

  As described above, the cured resin of the present invention is excellent in transparency and heat resistance, and is suitably used as an optical member because yellowing is remarkably suppressed even at a high temperature of about 260 ° C., for example. Examples of the optical member include an imaging lens, a spectacle lens, a filter, a diffraction grating, a prism, a light guide, and a light beam collection for a camera (on-vehicle camera, digital camera, PC camera, mobile phone camera, surveillance camera, etc.). Optical lens, light diffusion lens, cover glass for display device, photo sensor, photo switch, LED, light emitting element, optical waveguide, optical splitter, optical fiber adhesive, display element substrate, color filter substrate, touch panel substrate, Examples thereof include a display protective film, a display backlight, a light guide plate, and an antireflection film.

EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited by these Examples. Example 3 is described as a reference example.

Examples 1 to 8, Comparative Examples 1 and 2
Each component shown in the following Table 1 was blended according to the blending composition (numerical values are parts by weight), and stirred and mixed with a rotation / revolution mixer to obtain a uniform and transparent curable composition.

Abbreviations in Table 1 will be described.
[Component (A)]
EA-F5503: benzyl acrylate dilution of the compound represented by the following formula (1a) (content of the compound represented by the following formula (1a): 73% by weight), trade name “Ogsol EA-F5503”, Osaka Gas EA-0200 manufactured by Chemical Co., Ltd .: Contains 95% by weight of the compound represented by the following formula (1b), trade name “Ogsol EA-0200”, manufactured by Osaka Gas Chemical Co., Ltd. [Component (B)]
DVE: divinylbenzene represented by the following formula (2a) IRR214K: compound represented by the following formula (2j), trade name “IRR214K”, manufactured by Daicel Cytec Co., Ltd. A-LEN-10: the following formula (2c) A compound represented by the formula, “A-LEN-10”, manufactured by Shin-Nakamura Chemical Co., Ltd. [thermal radical polymerization initiator]
Perhexa C80: Trade name “Perhexa C-80”, 1,1-di (t-butylperoxy) cyclohexane, manufactured by NOF Corporation [Others]
Irg1010: Trade name “Irganox1010”, manufactured by Ciba Specialty Chemicals

  The curable compositions obtained in Examples and Comparative Examples were evaluated by the following methods.

[viscosity]
The viscosity of the curable composition was measured using a rheometer (trade name “PHYSICA UDS200”, manufactured by Paar Physica) at 25 ° C. and a rotation speed D = 20 / s (mPa · s).

[Applicability]
The curable compositions obtained in Examples and Comparative Examples were injected into a 10 mL syringe and defoamed using a rotation and revolution type mixer under reduced pressure. Then, using the high precision liquid agent coating device (trade name “dispenser ultra2400”, manufactured by EFD), application to the gap adjusted to a width of 1.0 mm was performed 5 times each and evaluated according to the following criteria.
Evaluation criteria Bubbles were not observed for all 5 times: ◎
Out of 5 bubbles were observed 1-2 times:
Out of 5 bubbles were observed 3-4 times: △
Bubbles were observed in all 5 times: ×

  Next, the curable compositions obtained in the examples and comparative examples were poured into a 0.5 mm-thick mold previously coated with a release agent and vapor-deposited, and preheated to 200 ° C. in an air atmosphere And then heated in an oven preheated to 140 ° C. for 2 minutes to release the mold. Thereafter, post-baking was further performed at 160 ° C. for 30 minutes to obtain cured resins (5 pieces each).

[Resin surface shape]
The surface of the cured resin obtained as described above was visually observed and evaluated according to the following criteria.
Evaluation criteria No pulse was observed for all five:
Out of the five, one or two were observed to be isolated: ○
Out of five, 3-4 were observed to have a pulse:
Disruption was observed in all five: ×

[Internal transmittance]
For the cured resin, the internal transmittance was calculated by the following formula.
Internal transmittance (400 nm) = light transmittance at 400 nm / (1-r) ²
r = {(n−1) / (n + 1)} ²
The light transmittance at 400 nm was measured using a spectrophotometer (manufactured by Hitachi High-Technologies Corporation, trade name “U-3900”). n is the refractive index at 400 nm, and the value of the refractive index at 400 nm measured by the following method was used.

[Refractive index]
The refractive index of the curable resin was measured by measuring the refractive index at 589 nm at 25 ° C. using a refractometer (trade name “Model 2010”, manufactured by Metricon) in accordance with JIS K7142.

[Abbe number]
The Abbe number of the cured resin was calculated by the following formula.
Abbe number = (n _d −1) / (n _f −n _c )
In the formula, n _d represents a refractive index at 589.2 nm, n _f represents a refractive index at 486.1 nm, and n _c represents a refractive index at 656.3 nm. In addition, the value of the refractive index in each wavelength measured by the said method was used for the refractive index.

[Glass-transition temperature]
The glass transition temperature of the cured resin is increased by a pre-treatment (from −50 ° C. to 250 ° C. at a rate of 20 ° C./minute) using a differential scanning calorimeter (trade name “Q2000”, manufactured by TA Instruments). Subsequently, the temperature was decreased from 250 ° C. to −50 ° C. at −20 ° C./min), and then measured at a temperature rising rate of 20 ° C./min and a measurement temperature range of −50 ° C. to 250 ° C.

[Linear expansion coefficient]
The linear expansion coefficient of the cured resin is measured by using a TMA measuring device (trade name “TMA / SS100”, manufactured by SII Nano Technology Co., Ltd.). The rate was measured and the slope of the straight line on the low temperature side was expressed as the coefficient of linear expansion. Moreover, the description in Table 2 is shown by linear expansion coefficient (ppm / ° C.) below the glass transition temperature / linear expansion coefficient (ppm / ° C.) above the glass transition temperature.

[Heat resistance test]
The cured resin was continuously subjected to a heat resistance test based on the reflow temperature profile described in JEDEC standards three times using a table reflow oven manufactured by Shin-Apec Co., Ltd., and the light transmittance and refractive index at 400 nm were measured by the above method. Then, the internal transmittance after the heat resistance test was obtained, and the yellowing rate (%) was obtained from the internal transmittance before and after the heat resistance test by the following formula, and the heat resistance was evaluated.
Yellowing rate (%) = {(Internal transmittance before heat resistance test) − (Internal transmittance after heat resistance test)} / (Internal transmittance before heat resistance test) × 100

The evaluation results are summarized in the following table.

  According to the curable composition of the present invention, since it is excellent in fluidity before being cured, it can be uniformly applied to a mold while suppressing the generation of bubbles. Moreover, since it can harden rapidly by heating, the metal metal mold | die which an elaborate work is easy can be used as a metal mold | die, and the shape of a metal mold | die can be reproduced with high precision. Therefore, a member having a desired shape such as a fine structure can be accurately and efficiently manufactured by a casting molding method or the like. In addition, the cured resin thus obtained has an Abbe number of 30 or less, is excellent in transparency and heat resistance, and has an effect of suppressing yellowing even at a high temperature of about 260 ° C. It is suitable for the use of optical members such as lenses.

Claims (7)

The following component (A) and component (B) are blended ratio [the former / the latter (weight ratio)] in a ratio of 70/30 to 99/1, and a curable composition containing a thiol compound,
The thiol compound is a linear alkanethiol or alkanedithiol having 10 to 15 carbon atoms,
The amount of the thiol compound used is 0.05 to 3% by weight based on the total amount of the curable monomer,
The curable composition whose glass transition temperature of the curable resin formed from a curable composition is 100 degreeC or more.
Component (A): Formula (1) below

(In the formula, rings Z ¹ and Z ² are the same or different and each represents an aromatic carbocycle. R ¹ and R ³ are the same or different and each represents an alkylene group; R ² and R ⁴ are the same or different; A hydrogen atom or a methyl group, n ¹ and n ² are the same or different and represent an integer of 0 or more)
A compound having two (meth) acryloyloxy groups in the molecule and having a fluorene ring Component (B): having at least one vinyl group or (meth) acryloyloxy group in the molecule And a compound having no fluorene ring Component (B) is represented by the following formula (2)

(In the formula, X represents a monovalent or divalent aliphatic hydrocarbon group, alicyclic hydrocarbon group, monocyclic aromatic hydrocarbon group or a group to which these groups are bonded. R ⁵ represents an alkylene group. R ⁶ represents a hydrogen atom or a methyl group, n ³ represents an integer of 0 or more, n ⁴ represents 0 or 1, and n ⁵ represents 1 or 2.
The curable composition of Claim 1 which is a compound represented by these.   The curable composition according to claim 1 or 2, wherein the viscosity at 25 ° C is 3600 mPa · s or less.   The curable composition according to any one of claims 1 to 3, wherein the thiol compound has a boiling point of 100 ° C or higher.   It is thermosetting, The curable composition as described in any one of Claims 1-4. Curable resin of the curable composition in any one of Claims 1-5.   An optical member made of the cured resin according to claim 6.