JP2011038017A - Acrylic monomer, curable composition including the same, and acrylic resin obtained by curing the composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acrylic monomer that satisfies the requirement of low volatility and further has a higher refractive index than conventional ones. <P>SOLUTION: The acrylic monomer is represented by general formula (1) and has less than 5 wt.% of weight reduction at 100°C when raising the temperature on the condition of 10°C/min under atmosphere. In the general formula, R<SB>1</SB>is H or CH<SB>3</SB>; and R<SB>2</SB>and R<SB>3</SB>are CH and CH<SB>2</SB>, or CH<SB>2</SB>and CH, respectively. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an acrylic monomer, a thermosetting composition or a photocurable composition containing the same, and an acrylic resin obtained by thermosetting or photocuring the composition.

  Acrylic resins widely used as materials for optical parts such as lenses because they are colorless and transparent and have high mechanical strength and moldability are generally obtained by polymerizing or copolymerizing acrylic acid, methacrylic acid or esters thereof. It is done.

  In synthesizing the acrylic resin, for example, the monomer component is radically polymerized by irradiating light to the photocurable composition containing the monomer component and the photopolymerization initiator. In this polymerization process, the monomer component is easily volatilized. There is a problem. For example, there is a problem such as deterioration of the working environment due to volatile components drifting around. Further, due to the volatilization of the monomer component, there arises a problem that it is difficult to control the characteristics of the acrylic resin such as the refractive index and the refractive index distribution by adjusting the ratio of the plurality of monomer components. For example, methyl methacrylate (methyl methacrylate), which is widely used as a monomer component, has high volatility even at room temperature, and therefore, when heated to about 60 ° C., almost the entire amount is volatilized.

  Therefore, in order to reduce the volatility of the acrylic monomer component, for example, the vapor pressure is reduced by introducing a specific substituent into the monomer component. For example, Patent Document 1 describes a (meth) acrylate compound modified to have low odor.

  However, conventionally known modified acrylic monomers are not sufficiently reduced in volatility as raw materials for optical materials. Further, as a raw material for the optical material, it is desirable that the refractive index is high, but there is no material that sufficiently satisfies this requirement.

JP-A-7-97351

  The present invention has been made to solve the above-mentioned problems, and its main object is to provide an acrylic monomer having low volatility and a higher refractive index than conventional products.

  The present invention solves the above-mentioned problems with a modified acrylic monomer having a specific functional group. An acrylic monomer, a thermosetting composition or a photocurable composition containing the acrylic monomer, and the composition Relates to an acrylic resin obtained by heat-curing or photo-curing.

  Specifically, the present invention relates to an acrylic monomer whose weight loss at 200 ° C. is less than 5% by weight when the temperature is raised under the condition of 10 ° C./min in the atmosphere. The acrylic monomer preferably has a refractive index of 1.45 or more at 20 ° C. The acrylic monomer has the following general formula (1)

〔式中Ｒ_１はＨまたはＣＨ₃、Ｒ_２、Ｒ_３はそれぞれＣＨ、ＣＨ₂またはＣＨ₂、ＣＨを示す。〕
で示される。
さらに本発明は、上記アクリル系モノマー及び熱重合開始剤または光重合開始剤を含有する硬化性組成物及び該硬化性組成物に対し加熱または光を照射することによって得られるアクリル系樹脂を提供する。該アクリル系樹脂は、光学材料となるものである。

[Wherein R ₁ represents H or CH ₃ , R ₂ and R ₃ represent CH, CH ₂ or CH ₂ and CH, respectively. ]
Indicated by
Furthermore, the present invention provides a curable composition containing the acrylic monomer and a thermal polymerization initiator or a photopolymerization initiator, and an acrylic resin obtained by heating or irradiating the curable composition. . The acrylic resin is an optical material.

  Hereinafter, the present invention will be described in detail. When the acrylic monomer of the present invention is heated at 10 ° C./min in the atmosphere, the weight reduction rate at 50 ° C. is suppressed to less than 1 wt%, and the weight loss at 100 ° C. is less than 5 wt%. Therefore, the low volatility requirement is sufficiently satisfied. Moreover, since the viscosity at 20 ° C. (normal temperature) is as low as 10 mPa · s or less, handling is easy.

  The acrylic monomer of the present invention has the following general formula (1)

〔式中Ｒ_１はＨまたはＣＨ₃、Ｒ_２、Ｒ_３はそれぞれＣＨ、ＣＨ₂またはＣＨ₂、ＣＨを示す。〕
で示される。

[Wherein R ₁ represents H or CH ₃ , R ₂ and R ₃ represent CH, CH ₂ or CH ₂ and CH, respectively. ]
Indicated by

  The acrylic monomer represented by the general formula (1) becomes an acrylic resin by thermal polymerization or photopolymerization. The acrylic monomer of the present invention has a higher refractive index than known acrylic monomers. For example, in the general formula (1), the refractive index at 20 ° C. (normal temperature) is as high as 1.45 or more (preferably about 1.5). In the case of methyl methacrylate (MMA), which is a publicly known acrylic monomer, the refractive index is about 1.4. Therefore, the refractive index is higher than that of MMA, which is advantageous for application to optical materials.

  In addition, the acrylic monomer of the present invention can be used not only as a monomer material alone but also as a monomer material for producing an acrylic resin in a form mixed with other polymerizable monomers. Other monomer components that can be mixed will be described later.

  The production method of the acrylic monomer represented by the general formula (1) is not limited, but can be suitably produced by, for example, a production method in which methallylic acid and 2-indanol are reacted. An example of the reaction scheme is shown below.

  2-norbornene methanol is reacted with methacrylic acid to introduce a norbornene group at the terminal. The reaction product is norbornene methacrylate. Since the intermolecular interaction of methacrylic acid is increased by introducing the norbornene group, the volatility (vapor pressure) of the methacrylic monomer finally obtained can be reduced.

  When preparing a thermosetting composition or photocurable composition containing the methacrylic monomer, the acrylic monomer and the thermal polymerization initiator or photopolymerization initiator may be substantially mixed. Depending on the case, other thermopolymerizable or photopolymerizable monomer components and known additives may be included.

  Examples of other thermopolymerizable or photopolymerizable monomers include, for example, acrylic acid esters such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, benzyl acrylate, and dimethylaminoethyl. Acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, glycidyl acrylate and the like are exemplified, and as methacrylic acid ester, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, benzyl methacrylate, Dimethylaminoethyl methacrylate, Mud methacrylate, hydroxypropyl methacrylate, glycidyl methacrylate and the like. As the ethylenically unsaturated carboxylic acid, monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid are preferably used. In addition, dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid, or anhydrides and half thereof. Esters can also be used. Among these, methyl methacrylate (methyl acrylate) is particularly preferable.

  When other thermopolymerizable or photopolymerizable monomers are added, the addition amount is preferably 80% by weight or less, and preferably 60% by weight or less of the total monomer amount.

  Examples of the thermal polymerization initiator include peroxides such as lauroyl peroxide, benzoyl peroxide, di-isopropyl peroxydicarbonate, di-n-butyl peroxydicarbonate, and 2,2′-azobis (isobutyrate). Nitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 1,1'-azobis (cyclohexane-1-carbonitrile), azobis (2,4-dimethyl4-methoxyvaleronitrile), etc. System compounds. One of these may be used alone, or two or more may be used in combination. The amount of the polymerization initiator used is preferably about 0.01 to 10 parts by weight with respect to 100 parts by weight of the monomer component.

  Examples of the photopolymerization initiator include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-butyl ether, benzoin phenyl ether, benzyl diphenyl disulfide, dibenzyl, diacetyl, anthraquinone, naphthoquinone, 3,3′-dimethyl. -4-methoxybenzophenone, benzophenone, p, p'-bis (dimethylamino) benzophenone, 4,4'-bis (diethylamino) benzophenone, pivaloin ethyl ether, benzyldimethyl ketal, 1,1-dichloroacetophenone, p- t-butyldichloroacetophenone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-diethylthioxanthone, 2,2-diethoxyacetopheno 2,2-dimethoxy-2-phenylacetophenone, 2,2-dichloro-4-phenoxyacetophenone, phenylglyoxylate, α-hydroxyisobutylphenone, dibenzoparone, 1- (4-isopropylphenyl) -2-hydroxy- Examples include 2-methyl-1-propanone, 2-methyl- [4- (methylthio) phenyl] -2-morpholino-1-propanone, tribromophenylsulfone, tribromomethylphenylsulfone and the like. The addition amount of such a photopolymerization initiator is preferably about 0.1 to 10 parts by weight with respect to 100 parts by weight of the monomer component.

  In addition to the above components, the thermosetting composition or the photocurable composition may include a polymerization inhibitor, a chain transfer agent, a polymerization accelerator, a solvent, a plasticizer, a colorant, a surface tension, if necessary. Known additives such as modifiers, stabilizers, antifoaming agents, adhesion-imparting agents, and flame retardants can be blended.

  In order to cure the thermosetting composition, for example, the composition is poured into a mold material (for example, a lens mold) and then heated to about the 10-hour half-life temperature of the above-described thermal polymerization initiator.

  In order to cure the photocurable composition, for example, the composition is poured into a mold material (for example, a lens mold) and then irradiated with light (ultraviolet rays, electron beams, sunlight rays, etc.). Usually, irradiation is performed by ultraviolet irradiation, and as a light source at that time, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a xenon lamp, a metal halide lamp, a chemical lamp, or the like is used. The amount of irradiation is not limited and is adjusted according to the shape and size of the target cured product. After light irradiation, the curing can be completed by heating as necessary.

  The acrylic resin obtained by the curing is easy to control the refractive index distribution because the volatilization of the monomer component during polymerization is suppressed. Moreover, it is advantageous in that a desired acrylic resin can be obtained without deteriorating the working environment. Furthermore, since the monomer of the present invention has a low viscosity, it is easy to handle.

  Since the acrylic monomer of the present invention has low volatility, it is difficult to deteriorate the working environment during photopolymerization, and the refractive index distribution of the polymer is easy to control. Moreover, since the acrylic monomer of the present invention has a high refractive index, it is useful as a raw material for producing optical materials such as lenses.

2 is a result of 1H-NMR spectrum obtained in Test Example 1. FIG. 3 is a result of 13 C-NMR spectrum obtained in Test Example 1. FIG. 6 is a TG curve obtained in Test Example 4.

  In order to clarify the characteristics of the present invention, examples and comparative examples are shown below. However, the scope of the present invention is not limited to these examples.

Example 1
An acrylic monomer represented by the following chemical formula (2) was prepared. This acrylic monomer is represented by the general formula (1) in which R ₁ is CH ₃ , R ₂ is CH, and R ₃ is CH ₂ .

  A 200 mL three-necked flask is charged with a stirring bar, methacrylic acid (9.8 mL, 120 mmol), 2-norbornenemethanol (13 mL, 100 mmol), p-methoxyphenol (274 mL, 220 mmol) as a polymerization inhibitor, and toluene (14 mL) as ice. Stir for 1 hour with cooling. At that time, methanesulfonic acid (0.54 mL, 8.3 mmol) was added dropwise as a catalyst.

  Next, it was made to react by stirring at 100-110 degreeC for 3 hours. After the reaction, hexane was added.

  Next, it was neutralized with an aqueous sodium hydroxide solution (10%) and extracted with ether.

  Next, it was washed with brine, the organic layer was dried over anhydrous sodium hydroxide, and the solvent was distilled off under reduced pressure.

  As a result, 11.4 g of a pale yellow liquid was obtained. The product was norbornene methyl methacrylate. The product was identified by NMR (1H, 13C) measurement (manufactured by JEOL, FT-NMR Spectrometer, JNM-GSX270).

(Comparative Example 1)
Methyl methacrylate (MMA) was used as an acrylic monomer.

(Test Example 1)
The result of 1H-NMR spectrum is shown in FIG. In FIG. 1, a is a hydrogen atom of a methyl group bonded to a vinyl group, b is a hydrogen atom of a vinyl group, c is a hydrogen atom bonded to a carbon atom bonded to an oxygen atom, and d is a hydrogen atom of a norbornene group. Is a typical spectrum. The results of 13 C-NMR spectrum are shown in FIG. 2a is a carbon atom of a methyl group bonded to a vinyl group, b and c are carbon atoms of a vinyl group, d is a carbon atom of a carbonyl group, e is a carbon atom bonded to an oxygen atom, and f part is a norbornene group It is a typical spectrum of carbon hydrogen.
From the results of each spectrum, it was confirmed that the norbornene methacrylate represented by the formula (2) was synthesized.

(Test Example 2)
About the acrylic acid monomer of Example 1 and Comparative Example 1, the refractive index (nD) was measured at 20 ° C. The refractive index was measured by using “Multiwave Abbe Refractometer DR-M2” manufactured by Atago Co., Ltd. The viscosity was measured using “Rotational Viscometer HBDV-III (Spindle: CP-42)” manufactured by Brookfield.

  The measurement results are shown in Table 1 below.

(Test Example 3)
0.5 parts by weight of benzoyl peroxide (BPO, Benzoyl peroxide) is added to each of the acrylic monomers of Example 1 and Comparative Example 1, and normal dodecyl mercaptan (n-DM, n-DM, n-dodecylamine mercaptan) is added as a chain transfer agent. 0.05 part by weight was added. After completely dissolving benzoyl peroxide, it is poured into a concave portion of a 10 × 10 × 5 mm mold and thermally polymerized in a dryer at 50 ° C. for 5 hours to obtain a transparent resin plate of 10 × 10 × 5 mm Got. The resin plate was measured for refractive index (nD) and Abbe number (νD) at 20 ° C. The refractive index and Abbe number were measured using “Multiwave Abbe Refractometer DR-M2” manufactured by Atago Co., Ltd.

  The measurement results are shown in Table 2 below.

(Test Example 4)
Thermogravimetric (TG) analysis was performed by raising the temperature of the acrylic monomers of Example 1 and Comparative Example 1 from room temperature to 250 ° C. under the condition of 10 ° C./min. As a thermogravimetric analyzer, “Thermo plus 2 TG7120” manufactured by Rigaku was used.

  The analysis result (TG curve) is shown in FIG. Compared to MMA (Comparative Example 1), it can be seen that the acrylic monomer of Example 1 has a significantly reduced volatility.

Claims (6)

An acrylic monomer having a weight loss at 100 ° C. of less than 5% by weight when heated at 10 ° C./min in the atmosphere. The acrylic monomer according to claim 1, wherein the acrylic monomer has a refractive index of 1.45 or more at 20 ° C. The acrylic monomer has the following general formula (1)

[Wherein R ₁ represents H or CH ₃ , R ₂ and R ₃ represent CH, CH ₂ or CH ₂ and CH, respectively. ]

The acrylic monomer of Claim 1 or 2 shown by these. A curable composition comprising the acrylic monomer according to claim 1 and a thermal polymerization initiator or a photopolymerization initiator. The acrylic resin obtained by heating or irradiating light to the curable composition in any one of Claims 1-3. The acrylic resin according to claim 5, which is an optical material.

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