JP4058287B2 - Molded body of poly (meth) acrylic copolymer - Google Patents

Description

（式中、Ｒは水素原子またはメチル基を表す。）
以下、本発明を詳細に説明する。
【０００７】
【発明の実施の形態】
本発明におけるポリ（メタ）アクリル系共重合体の単量体単位を構成する一般式（１）で表わされる（メタ）アクリル酸誘導体は、メタクリル酸２−デカハイドロナフチルまたはアクリル酸２−デカハイドロナフチルであり、好ましくは、メタクリル酸２−デカハイドロナフチルである。
【０００８】
また、本発明における共重合体を構成する一般式（１）で表わされる単量体単位と共重合される他の単量体単位としては、不飽和脂肪酸エステル、芳香族ビニル化合物、シアン化ビニル化合物、不飽和二塩基酸またはその誘導体、不飽和脂肪酸またはその誘導体等があり、これらの化合物の二種以上を使用することもできる。
【０００９】
上記不飽和脂肪酸エステルとしては、（メタ）アクリル酸メチル、（メタ）アクリル酸エチル、（メタ）アクリル酸ブチル、（メタ）アクリル酸２―エチルヘキシル等の（メタ）アクリル酸アルキルエステル、（メタ）アクリル酸シクロヘキシル、（メタ）アクリル酸メチルシクロヘキシル、（メタ）アクリル酸ボルニル、（メタ）アクリル酸イソボルニル、（メタ）アクリル酸アダマンチル等の（メタ）アクリル酸シクロアルキルエステル、（メタ）アクリル酸フェニル、（メタ）アクリル酸ベンジル等の（メタ）アクリル酸芳香族エステル、（メタ）アクリル酸フルオロフェニル、（メタ）アクリル酸クロロフェニル、（メタ）アクリル酸フルオロベンジル、（メタ）アクリル酸クロロベンジル等の（メタ）アクリル酸置換芳香族エステル、（メタ）アクリル酸フルオロメチル、（メタ）アクリル酸フルオロエチル等の（メタ）アクリル酸ハロゲン化アルキルエステル、（メタ）アクリル酸ヒドロキシアルキルエステル、（メタ）アクリル酸グリシジル、（メタ）アクリル酸エチレングリコールエステル、（メタ）アクリル酸ポリエチレングリコールエステル等の（メタ）アクリル酸エステル等が挙げられる。
なお、「（メタ）アクリル」とは「アクリル」または「メタクリル」を意味する。
【００１０】
芳香族ビニル化合物としては、スチレン、α−メチルスチレン、α−エチルスチレン等のα−置換スチレン、フルオロスチレン、メチルスチレン等の核置換スチレン等が挙げられる。
シアン化ビニル化合物としては、アクリロニトリル、メタクリロニトリル等が挙げられる。
【００１１】
不飽和二塩基酸またはその誘導体としては、Ｎ−メチルマレイミド、Ｎ−エチルマレイミド、Ｎ−プロピルマレイミド、Ｎ−シクロヘキシルマレイミド、Ｎ−フェニルマレイミド、Ｎ−クロロフェニルマレイミド等のＮ−置換マレイミド、マレイン酸、無水マレイン酸、フマル酸等が挙げられる。
【００１２】
不飽和脂肪酸およびその誘導体としては、（メタ）アクリルアミド、Ｎ，Ｎ−ジメチル（メタ）アクリルアミド、Ｎ，Ｎ−ジエチル（メタ）アクリルアミド等の（メタ）アクリルアミド類、（メタ）アクリル酸カルシウム、（メタ）アクリル酸バリウム、（メタ）アクリル酸鉛、（メタ）アクリル酸すず、（メタ）アクリル酸亜鉛等の（メタ）アクリル酸の金属塩、（メタ）アクリル酸等が挙げられる。
以上の本発明の共重合体を構成する一般式（１）で表わされる単量体単位と共重合される他の単量体単位としては、最も好ましいものは、メタクリル酸メチルである。
【００１３】
本発明における共重合体の好ましい単量体組成は、一般式（１）で表される単量体単位が５〜９５質量％、より好ましくは５〜５０質量％、メタクリル酸メチル単位が５〜９５質量％より好ましくは、５０〜７０質量％、他の単量体単位が０〜２５質量％である。
【００１４】
一般式（１）で表される単量体単位が少なすぎると、良好な耐熱性、低吸湿性が発現しない。また、多すぎると、機械的強度が著しく悪化し、機械的強度保持の点より、５０質量％以下が好ましい。
【００１５】
本発明における共重合体を得る方法としては、塊状重合法、懸濁重合法、乳化重合法等の公知の方法が可能であるが、取扱の容易さから懸濁重合法が好ましい。本発明の共重合体を懸濁重合法により製造する場合について説明する。まず、前記の一般式（１）で表わされる単量体と、これと共重合可能な他の単量体とからなる単量体混合物に、重合開始剤および必要に応じて連鎖移動剤を溶解させる。
次いで、その得られた均一混合液を分散安定剤を存在させた水媒体に懸濁した後、所定の重合温度で一定時間保持して重合を完結させ、その得られた懸濁重合物を濾過し、水洗、乾燥することにより共重合体を得ることができる。
【００１６】
懸濁重合の際に使用される重合開始剤としては、例えば、２，２’−アゾビスイソブチロニトリル、２，２’−アゾビス−２，４−ジメチルバレロニトリル等のアゾ系開始剤、ベンゾイルパーオキサイド、ｔ−ブチルパーオキシ２−エチルヘキサノエート、１，１−ジ−ｔ−ブチルパーオキシ−２−メチルシクロヘキサン等の過酸化物系開始剤等を挙げることができる。これらの重合開始剤の使用量は、上記単量体混合物１００質量部に対して０．００１〜３質量部の範囲が好ましい。
【００１７】
懸濁重合の際に使用される連鎖移動剤としては、例えばｔ−ブチルメルカプタン、ｎ−ブチルメルカプタン、ｎ−オクチルメルカプタン、ｎ−ドデシルメルカプタン等を挙げることができる。これらの連鎖移動剤の使用量は、上記単量体混合物１００質量部に対して０〜３質量部の範囲が好ましい。
【００１８】
また、懸濁重合の際に使用される分散剤としては、ポリビニルアルコール、（メタ）アクリル酸の単独重合体あるいは共重合体のアルカリ金属塩、メタクリル酸メチルとメタクリル酸２−スルホエチルのナトリウム塩の共重合体、カルボキシルセルロース、ゼラチン、デンプン、硫酸バリウム、硫酸カルシウム、炭酸カルシウム、炭酸マグネシウム、燐酸カルシウム等を挙げることができる。これらの分散剤の使用量は、水１００質量部に対して、０．０１〜５質量部の範囲が好ましい。また、必要に応じて、これらの分散剤と共に、塩化ナトリウム、塩化カリウム、硫酸ナトリウム、硫酸カリウム、硫酸マンガン等の分散助剤を併用することもできる。
【００１９】
懸濁重合の際に使用される水量としては、特に限定されないが、上記単量体混合物１００質量部に対して１００〜１０００質量部の範囲が好ましく、より好ましくは１５０〜４００質量部の範囲である。
また、懸濁重合の重合温度としては、特に限定されないが、５０〜１５０℃の範囲が好ましく、より好ましくは、５０〜１３０℃の範囲である。
【００２０】
上記のようにして得られた共重合体には、目的に応じて、公知の添加剤、例えば染料、顔料等の着色剤、各種酸化防止剤、可塑剤、離型剤、紫外線吸収剤などの光安定剤等を添加して成形することができる。
【００２１】
本発明における共重合体は、成型加工性に優れ、押出成形法、射出成形法、圧縮成形法等の公知の方法で各種の成形体に成形可能である。また、押出成形法によりペレット形状とし、そのペレットをさらに成形することもできる。特に本発明の耐熱性樹脂共重合体は、２５０℃以上の温度において分解が少ないため、高温成形が可能であり、生産性から射出成形法が好ましい。
【００２２】
また、本発明における共重合体は、光学用透明部材、自動車部品、照明器具、オーディオ部品、ＯＡ機器部品などに使用可能である。特に、低吸湿性と耐熱性に優れるため、吸湿または高温時の寸法安定性が良好で、環境による光学性能の変化が少なく、かつ、透明性にも優れるため、光学用透明性の成形品として好適である。
光学用透明部材の例としては、情報伝送体、情報記録媒体、撮像系レンズ、ピックアップレンズ、ｆθレンズ等が挙げられる。
【００２３】
【実施例】
次に、実施例によって本発明を具体的に説明するが、本発明はこれらによって限定されるものではない。
各実施例、比較例おいて用いられた単量体の略号は、以下の化合物を示す。
ＤＮＭＡ ：メタクリル酸２−デカハイドロナフチル
ＭＭＡ ：メタクリル酸メチル
ＣＨＭＡ ：メタクリル酸シクロヘキシル
ＩＢＭＡ ：メタクリル酸イソボルニル
ＭＡ ：アクリル酸メチル
【００２４】
また、実施例および比較例で得た（共）重合体からなる成形体の物性の評価項目、評価方法は、次の通りである。
１）全光線透過率、曇価
ペレット状（共）重合体から１００ｍｍ（長さ）×５０ｍｍ（幅）×２ｍｍ（厚み）の平板を射出成形により作製した後、ＡＳＴＭ−Ｄ１００３に準拠して測定した。
【００２５】
２）吸湿率
ペレット状（共）重合体から１００ｍｍ（長さ）×５０ｍｍ（幅）×２ｍｍ（厚み）の平板を射出成形により作製し、７５℃で４８時間乾燥後の質量（１）を測定した。次いで、６０℃、９０％ＲＨの恒温恒湿下に４８０時間放置後の質量（２）を測定し、下記数式１により吸湿率を算出した。
【数１】

【００２６】
３）荷重たわみ温度（ＨＤＴ）
ペレット状（共）重合体から１２７ｍｍ（長さ）×１２．７ｍｍ（幅）×６．４ｍｍ（厚み）の試片を加圧成形により作製した後、ＡＳＴＭ−Ｄ６４８に準拠して測定した。
４）曲げ強度
ペレット状（共）重合体から１２７ｍｍ（長さ）×１２．７ｍｍ（幅）×６．４ｍｍ（厚み）の試片を射出成形により作製した後、ＡＳＴＭ−Ｄ７９０に準拠して測定した。
【００２７】
５）熱安定性
重合で得られたビーズ状（共）重合体をＴＨＦ（テトラヒドロフラン）に溶解した液をメタノール中に滴下し、再沈ポリマーを調製した。次いで、濾過により再沈ポリマーを回収した後、真空乾燥機を使用し、５０℃で２４時間乾燥させた。得られた再沈ポリマーを示差熱質量同時測定装置（セイコー電子工業（株）製ＳＥＩＫＯ ＤＴＡ／ＴＧＡ２２０）を使用し、以下の条件で３質量％、５質量％、１０質量％減少温度を測定した。
測定条件：
雰囲気：窒素（流量２００ｍｌ／ｍｉｎ）
１ｓｔステップ：４０℃→１００℃（昇温速度１００℃／ｍｉｎ）、
１００℃で６０ｍｉｎ保持。
２ｎｄステップ：１００℃→５００℃（昇温速度１０℃／ｍｉｎ）
【００２８】
実施例１：
攪拌機を備えた反応容器に、ＤＮＭＡ７０質量％、ＭＭＡ３０質量％の単量体混合物１００質量部を入れ、重合開始剤として２，２’−アゾビスイソブチロニトリル０．１質量部、連鎖移動剤としてｎ−オクチルメルカプタン０．２質量部、離型剤としてステアリルアルコール０．３質量部を加え攪拌溶解させた。また、別の容器に脱イオン水２００質量部を入れ、分散剤としてポリビニルアルコール０．５質量部、分散助剤として硫酸ナトリウム０．５質量部を加え攪拌溶解した。次いで、別容器で攪拌溶解した脱イオン水混合物を攪拌機を備えた反応容器に投入し、窒素置換しながら３５０ｒｐｍで１５分間攪拌した。その後、７５℃に加温して重合を開始させ、重合ピーク後、９５℃、３０分間の熱処理を行い、重合を完結させた。
【００２９】
得られたビーズ状共重合体を濾過、水洗し、７５℃で２４時間乾燥した後、池貝（株）製ＰＣＭ３０，２軸押出機を用いて、シリンダー温度２３０℃で押出しペレット化した。その後、日精樹脂（株）製、射出成形機ＰＳ−６０Ｅを用いて、シリンダー温度２５０℃、金型温度７５℃で試片作製を行い、全光線透過率、吸湿率、曲げ強度を評価した。また、庄司鉄工（株）製プレス機を用いて、プレス温度２００℃、プレス圧力３ＭＰａで試片作製を行い、荷重たわみ温度を評価した。また、得られたビーズ状共重合体を用い、熱安定性を評価した。
【００３０】
実施例２〜３、比較例１〜４：
単量体混合物の仕込組成を表１に示すように変更した以外は、実施例１と同様に重合、ペレット化、試片作製等を行い、全光線透過率、吸湿率、荷重たわみ温度、曲げ強度、熱安定性を評価した。得られた成形品の評価結果を一括して表１に示すが、比較例１は、強度不足で各評価用試片が得られなかったため、全光線透過率、曇価、吸湿率、荷重たわみ温度、曲げ強度を評価することができなかった。
上記実施例および比較例で得られた共重合体からなる成形品の評価結果を表１に示す。
【００３１】
【表１】

【００３２】
【発明の効果】
以上詳細に説明したように、本発明におけるポリ（メタ）アクリル系共重合体からなる成形体は、２５０℃以上の高温下において熱安定性が良好で、かつ、透明性、耐熱性および低吸湿性のバランスに優れるため、情報伝送体、情報記録媒体、撮像系レンズ、ピックアップレンズ、ｆθレンズ等の光学用透明部材、テールランプ、バックパネル等の自動車部品、ランプカバーやルーバー等の照明器具、チューナー等のインジケーター、メーターカバー等のオーディオ部品、ＯＡ機器部品等の材料として使用でき、特に光学用透明性成形体として有用である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a molded article made of a novel poly (meth) acrylic copolymer excellent in transparency, thermal stability, low hygroscopicity, and heat resistance.
[0002]
[Prior art]
Methacrylic resin is a resin that excels in transparency, light resistance, low birefringence, and has a good balance of mechanical properties and moldability, so that information transmission bodies, information recording media, imaging lenses, pickup lenses, It is widely used for optical transparent members such as fθ lenses, automobile parts such as tail lamps and back panels, lighting equipment such as lamp covers and louvers, indicators such as tuners, audio parts such as meter covers, and OA equipment parts. However, the use of methacrylic resin may be limited due to the drawback of higher hygroscopicity or lower heat resistance than resins such as polycarbonate, polystyrene, and amorphous polyolefin.
[0003]
On the other hand, a methacrylic resin comprising a methyl methacrylate unit and a cyclohexyl methacrylate unit or an isobornyl methacrylate unit has been proposed (Japanese Patent Laid-Open Nos. 58-5318 and 60-115605). These resins have excellent transparency and light resistance equivalent to those of conventional methacrylic resins, and are excellent resins having low moisture absorption that cannot be obtained with methacrylic resins.
However, a methacrylic resin composed of methyl methacrylate units and cyclohexyl methacrylate units has a drawback that the deflection temperature under load (HDT) is greatly reduced.
On the other hand, methacrylic resin consisting of methyl methacrylate units and isobornyl methacrylate units is significantly decomposed in the molding temperature range of optical transparent members, automobile parts, lighting equipment, audio parts, OA equipment parts, etc. There are drawbacks such as reduced performance.
[0004]
[Problems to be solved by the invention]
It is an object of the present invention to have good thermal stability, transparency and low moisture absorption at a high temperature of 250 ° C. or higher where optical transparent members, automobile parts, lighting equipment, audio parts, OA equipment parts, etc. are molded. Another object of the present invention is to provide a molded article made of a heat-resistant resin copolymer having an excellent balance of properties.
[0005]
[Means for Solving the Problems]
As a result of diligent studies to achieve the above-mentioned goal, the present inventors have found that a poly (meth) acrylic copolymer containing a (meth) acrylic acid derivative represented by the following general formula (1) as a unit component. It has been found that the coalescence is a resin having extremely excellent properties in the above characteristics. The present invention has been made based on such findings.
[0006]
That is, the present invention
5 to 95% by mass of monomer units represented by the general formula (1), 5 to 95% by mass of methyl methacrylate units, and 0 to 25% by mass of other monomer units copolymerizable other than methyl methacrylate units; A poly (meth) acrylic copolymer made of the above is provided at a molding temperature of 200 ° C. or higher .
[Chemical 2]

(In the formula, R represents a hydrogen atom or a methyl group.)
Hereinafter, the present invention will be described in detail.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
The (meth) acrylic acid derivative represented by the general formula (1) constituting the monomer unit of the poly (meth) acrylic copolymer in the present invention is 2-decahydronaphthyl methacrylate or 2-decahydroacrylate. Naphthyl, preferably 2-decahydronaphthyl methacrylate.
[0008]
Other monomer units copolymerized with the monomer unit represented by the general formula (1) constituting the copolymer in the present invention include unsaturated fatty acid esters, aromatic vinyl compounds, and vinyl cyanide. There are compounds, unsaturated dibasic acids or derivatives thereof, unsaturated fatty acids or derivatives thereof, and two or more of these compounds can also be used.
[0009]
Examples of the unsaturated fatty acid esters include (meth) acrylic acid alkyl esters such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate, (meth) (Meth) acrylic acid cycloalkyl ester such as cyclohexyl acrylate, methyl cyclohexyl (meth) acrylate, bornyl (meth) acrylate, isobornyl (meth) acrylate, adamantyl (meth) acrylate, phenyl (meth) acrylate, (Meth) acrylic acid aromatic esters such as benzyl (meth) acrylate, fluorophenyl (meth) acrylate, chlorophenyl (meth) acrylate, fluorobenzyl (meth) acrylate, chlorobenzyl (meth) acrylate ( (Meth) acrylic acid substituted aromatic esthetics , (Meth) acrylic acid halogenated alkyl esters such as fluoromethyl (meth) acrylate and fluoroethyl (meth) acrylate, hydroxyalkyl esters of (meth) acrylic acid, glycidyl (meth) acrylate, ethylene (meth) acrylate Examples include (meth) acrylic acid esters such as glycol esters and (meth) acrylic acid polyethylene glycol esters.
“(Meth) acryl” means “acryl” or “methacryl”.
[0010]
Examples of the aromatic vinyl compound include α-substituted styrene such as styrene, α-methylstyrene, α-ethylstyrene, and nucleus-substituted styrene such as fluorostyrene and methylstyrene.
Examples of the vinyl cyanide compound include acrylonitrile and methacrylonitrile.
[0011]
Examples of unsaturated dibasic acid or derivatives thereof include N-substituted maleimides such as N-methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-chlorophenylmaleimide, maleic acid, Examples thereof include maleic anhydride and fumaric acid.
[0012]
Unsaturated fatty acids and derivatives thereof include (meth) acrylamides such as (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, calcium (meth) acrylate, (meta ) Barium acrylate, lead (meth) acrylate, tin (meth) acrylate, metal salt of (meth) acrylic acid such as zinc (meth) acrylate, (meth) acrylic acid and the like.
As the other monomer unit copolymerized with the monomer unit represented by the general formula (1) constituting the copolymer of the present invention, methyl methacrylate is most preferable.
[0013]
The preferable monomer composition of the copolymer in the present invention is 5 to 95% by mass of the monomer unit represented by the general formula (1), more preferably 5 to 50% by mass, and 5 to 5% of methyl methacrylate units. More preferably, it is 50 to 70% by mass, and other monomer units are 0 to 25% by mass.
[0014]
When there are too few monomer units represented by General formula (1), favorable heat resistance and low hygroscopicity will not be expressed. Moreover, when too large, mechanical strength will deteriorate remarkably and 50 mass% or less is preferable from the point of mechanical strength maintenance.
[0015]
As a method for obtaining the copolymer in the present invention, known methods such as a bulk polymerization method, a suspension polymerization method, and an emulsion polymerization method are possible, but the suspension polymerization method is preferable because of easy handling. The case where the copolymer of the present invention is produced by a suspension polymerization method will be described. First, a polymerization initiator and, if necessary, a chain transfer agent are dissolved in a monomer mixture comprising the monomer represented by the general formula (1) and another monomer copolymerizable therewith. Let
Next, the obtained homogeneous mixed solution is suspended in an aqueous medium containing a dispersion stabilizer, and then held at a predetermined polymerization temperature for a certain period of time to complete the polymerization, and the obtained suspension polymer is filtered. and, washing with water, it can be obtained by Ri copolymer to dry.
[0016]
Examples of the polymerization initiator used in the suspension polymerization include azo initiators such as 2,2′-azobisisobutyronitrile and 2,2′-azobis-2,4-dimethylvaleronitrile, Examples thereof include peroxide initiators such as benzoyl peroxide, t-butylperoxy 2-ethylhexanoate, and 1,1-di-t-butylperoxy-2-methylcyclohexane. The amount of these polymerization initiators used is preferably in the range of 0.001 to 3 parts by mass with respect to 100 parts by mass of the monomer mixture.
[0017]
Examples of the chain transfer agent used in the suspension polymerization include t-butyl mercaptan, n-butyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan, and the like. The amount of these chain transfer agents used is preferably in the range of 0 to 3 parts by mass with respect to 100 parts by mass of the monomer mixture.
[0018]
Moreover, as a dispersing agent used in the case of suspension polymerization, polyvinyl alcohol, (meth) acrylic acid homopolymer or copolymer alkali metal salt, methyl methacrylate and sodium salt of 2-sulfoethyl methacrylate are used. Copolymers, carboxyl cellulose, gelatin, starch, barium sulfate, calcium sulfate, calcium carbonate, magnesium carbonate, calcium phosphate and the like can be mentioned. The amount of these dispersants used is preferably in the range of 0.01 to 5 parts by mass with respect to 100 parts by mass of water. If necessary, a dispersing aid such as sodium chloride, potassium chloride, sodium sulfate, potassium sulfate, manganese sulfate can be used in combination with these dispersants.
[0019]
Although it does not specifically limit as an amount of water used in the case of suspension polymerization, The range of 100-1000 mass parts is preferable with respect to 100 mass parts of said monomer mixtures, More preferably, it is the range of 150-400 mass parts. is there.
The polymerization temperature for suspension polymerization is not particularly limited, but is preferably in the range of 50 to 150 ° C, more preferably in the range of 50 to 130 ° C.
[0020]
Depending on the purpose, the copolymer obtained as described above may contain known additives such as colorants such as dyes and pigments, various antioxidants, plasticizers, mold release agents, and UV absorbers. It can be molded by adding a light stabilizer or the like.
[0021]
The copolymer in the present invention is excellent in molding processability and can be molded into various molded products by a known method such as an extrusion molding method, an injection molding method, or a compression molding method. Moreover, it can also be made into a pellet shape by an extrusion molding method, and the pellet can be further molded. In particular, since the heat resistant resin copolymer of the present invention has little decomposition at a temperature of 250 ° C. or higher, high temperature molding is possible, and an injection molding method is preferred from the viewpoint of productivity.
[0022]
The copolymer in the present invention can be used for optical transparent members, automobile parts, lighting equipment, audio parts, OA equipment parts, and the like. In particular, because it is excellent in low moisture absorption and heat resistance, it has good dimensional stability at moisture absorption or high temperature, there is little change in optical performance due to the environment, and it is excellent in transparency . Is preferred.
Examples of the optical transparent member include an information transmission body, an information recording medium, an imaging system lens, a pickup lens, and an fθ lens.
[0023]
【Example】
Next, the present invention will be specifically described by way of examples, but the present invention is not limited thereto.
The abbreviations of the monomers used in each Example and Comparative Example indicate the following compounds.
DNMA: 2-decahydronaphthyl methacrylate MMA: methyl methacrylate CHMA: cyclohexyl methacrylate IBMA: isobornyl methacrylate MA: methyl acrylate
In addition, the evaluation items and evaluation methods for the physical properties of the molded products made of the (co) polymers obtained in the examples and comparative examples are as follows.
1) Total light transmittance, haze value A flat plate of 100 mm (length) x 50 mm (width) x 2 mm (thickness) was prepared from a pellet-shaped (co) polymer by injection molding, and then measured according to ASTM-D1003. did.
[0025]
2) A flat plate of 100 mm (length) x 50 mm (width) x 2 mm (thickness) was produced from the moisture absorption pellet-like (co) polymer by injection molding, and the mass (1) after drying at 75 ° C for 48 hours was measured. did. Subsequently, the mass (2) after being left for 480 hours under constant temperature and humidity of 60 ° C. and 90% RH was measured, and the moisture absorption rate was calculated by the following formula 1.
[Expression 1]

[0026]
3) Deflection temperature under load (HDT)
A 127 mm (length) x 12.7 mm (width) x 6.4 mm (thickness) specimen was prepared from the pellet-shaped (co) polymer by pressure molding, and then measured according to ASTM-D648.
4) Bending strength A 127 mm (length) x 12.7 mm (width) x 6.4 mm (thickness) specimen was prepared from a pellet-shaped (co) polymer by injection molding and then measured according to ASTM-D790. did.
[0027]
5) A solution obtained by dissolving a bead-shaped (co) polymer obtained by heat-stable polymerization in THF (tetrahydrofuran) was dropped into methanol to prepare a reprecipitation polymer. Subsequently, after reprecipitation polymer was collect | recovered by filtration, it was made to dry at 50 degreeC for 24 hours using the vacuum dryer. Using the differential thermal mass simultaneous measurement device (SEIKO DTA / TGA220 manufactured by Seiko Denshi Kogyo Co., Ltd.), the reprecipitation polymer obtained was measured for 3 mass%, 5 mass%, and 10 mass% reduction temperature under the following conditions. .
Measurement condition:
Atmosphere: Nitrogen (flow rate 200ml / min)
1st step: 40 ° C. → 100 ° C. (temperature increase rate 100 ° C./min),
Hold at 100 ° C. for 60 min.
2nd step: 100 ° C. → 500 ° C. (temperature increase rate 10 ° C./min)
[0028]
Example 1:
In a reaction vessel equipped with a stirrer, 100 parts by mass of a monomer mixture of 70% by mass of DNMA and 30% by mass of MMA is added, 0.1 part by mass of 2,2′-azobisisobutyronitrile as a polymerization initiator, a chain transfer agent As a release agent, 0.2 parts by mass of n-octyl mercaptan and 0.3 parts by mass of stearyl alcohol as a release agent were added and dissolved by stirring. Moreover, 200 mass parts of deionized water was put into another container, 0.5 mass part of polyvinyl alcohol as a dispersing agent, and 0.5 mass part of sodium sulfate as a dispersion aid were added and dissolved by stirring. Next, the deionized water mixture stirred and dissolved in a separate container was put into a reaction vessel equipped with a stirrer, and stirred at 350 rpm for 15 minutes while purging with nitrogen. Thereafter, the polymerization was started by heating to 75 ° C., and after the polymerization peak, a heat treatment was performed at 95 ° C. for 30 minutes to complete the polymerization.
[0029]
The obtained bead copolymer was filtered, washed with water, dried at 75 ° C. for 24 hours, and then extruded and pelletized at a cylinder temperature of 230 ° C. using a PCM30, twin screw extruder manufactured by Ikegai Co., Ltd. Thereafter, specimens were prepared at a cylinder temperature of 250 ° C. and a mold temperature of 75 ° C. using Nissei Resin Co., Ltd. injection molding machine PS-60E, and the total light transmittance, moisture absorption rate and bending strength were evaluated. Further, using a press machine manufactured by Shoji Iron Works, a specimen was prepared at a press temperature of 200 ° C. and a press pressure of 3 MPa, and the deflection temperature under load was evaluated. Moreover, thermal stability was evaluated using the obtained bead-shaped copolymer.
[0030]
Examples 2-3 and Comparative Examples 1-4:
Except for changing the charge composition of the monomer mixture as shown in Table 1, polymerization, pelletization, specimen preparation, etc. were carried out in the same manner as in Example 1, total light transmittance, moisture absorption, deflection temperature under load, bending The strength and thermal stability were evaluated. The evaluation results of the obtained molded products are collectively shown in Table 1, but Comparative Example 1 was not able to obtain each evaluation specimen due to insufficient strength, so total light transmittance, haze value, moisture absorption, deflection of load The temperature and bending strength could not be evaluated.
Table 1 shows the evaluation results of the molded products made of the copolymers obtained in the above Examples and Comparative Examples.
[0031]
[Table 1]

[0032]
【The invention's effect】
As described above in detail, the molded body comprising the poly (meth) acrylic copolymer in the present invention has good thermal stability at a high temperature of 250 ° C. or higher, and has transparency, heat resistance and low moisture absorption. Excellent balance of properties, information transmission medium, information recording medium, imaging system lens, pickup lens, optical transparent member such as fθ lens, automobile parts such as tail lamp and back panel, lighting equipment such as lamp cover and louver, tuner It can be used as a material for audio parts such as indicators, meter covers, and OA equipment parts, and is particularly useful as a transparent molded article for optics.

Claims (3)

5 to 95% by mass of monomer units represented by the general formula (1), 5 to 95% by mass of methyl methacrylate units, and 0 to 25% by mass of other monomer units copolymerizable other than methyl methacrylate units; A molded article obtained by molding a poly (meth) acrylic copolymer comprising:

(In the formula, R represents a hydrogen atom or a methyl group.) The molded body according to claim 1, wherein the molded body is an optically transparent molded body. The molded body according to claim 1, wherein the molded body is a lens.