JP4592232B2

JP4592232B2 - Neutron shielding material composition, shielding material and container

Info

Publication number: JP4592232B2
Application number: JP2001241003A
Authority: JP
Inventors: 宣也林; 佳之田坂; 伸夫石原; 勝大崎; 俊一林; 由里子小西; 憲治名島
Original assignee: Mitsubishi Heavy Industries Ltd
Current assignee: Mitsubishi Heavy Industries Ltd
Priority date: 2001-08-08
Filing date: 2001-08-08
Publication date: 2010-12-01
Anticipated expiration: 2021-08-08
Also published as: JP2003050294A

Description

【０００１】
【発明の属する技術分野】
本発明は中性子遮蔽材用組成物に関する。更には、使用済核燃料の貯蔵および運搬用の容器であるキャスクに適用する材料であり、耐熱性が向上し、且つ中性子遮蔽性を確保したエポキシ樹脂系の中性子遮蔽材用の組成物に関する。
【０００２】
【従来の技術】
原子力発電所などの原子力施設で使用された核燃料は、通常、再処理工場に移送され、再処理に供される。しかし、現在では、このような使用済核燃料の発生量が、再処理能力を超えているため、使用済核燃料は長期にわたって貯蔵保管する必要性が生じている。この際、使用済核燃料は輸送に適した放射能レベルにまで冷却された後、キャスクに入れて輸送されるが、この段階でも中性子などの放射線を放出しつづけている。中性子はエネルギーが高く、ガンマ線を発生して人体に重大な傷害を与えるため、この中性子を確実に遮蔽する材料の開発が必要とされている。
【０００３】
中性子はホウ素によって吸収されることが知られているが、ホウ素が中性子を吸収するためには、中性子を減速する必要がある。中性子を減速するための物質としては水素が最適であることが知られている。このように、中性子遮蔽材用の組成物は、ホウ素と水素の原子を多く含む必要がある。
さらに、中性子の発生源である使用済核燃料等は崩壊熱を生じるため、輸送や貯蔵のために密閉しておくと発熱し高温となる。この最高温度は使用済み核燃料の種類によって異なるが、高燃焼度対応の使用済み核燃料ではキャスク内での温度は２００℃付近にまで達するといわれている。そこで、中性子遮蔽材として用いるには、このような高温条件下で、使用済み核燃料の貯蔵目安である約６０年間耐えうることが望ましい。
【０００４】
このため、遮蔽材としては水素密度の高い物質、特に水の使用が提案され、一部実用にも供されている。しかし、水は液体であるため、取り扱いが困難で、特に輸送と貯蔵を目的とするキャスクには適さない。また、キャスク内は１００℃以上に達するので、沸騰をおさえるのが困難であるといった問題がある。
【０００５】
そこで従来、中性子遮蔽材の１材料として樹脂組成物が用いられ、その樹脂組成物の１つにエポキシ樹脂が用いられてきた。一般的に樹脂組成物の水素含有量と耐熱性は相反関係にあり、水素含有量が多い物は耐熱性が低く、耐熱性が高い物は水素含有量が低い傾向にある。エポキシ樹脂は、耐熱性や硬化性には優れるものの、中性子を減速させるために必須である水素の含有量が少ないという傾向にあるため、従来はこれを水素含有量が多いアミン系の硬化剤を用いて補う方法が一般的であった。
特開平6-148388号公報には、多官能アミン系エポキシ樹脂を用い、粘度を低下させて常温での作業性を向上させるとともに、ポットライフに優れた中性子遮蔽材用組成物が開示されている。また、特開平9-176496号公報には、アクリル樹脂、エポキシ樹脂、シリコーン樹脂等からなる組成物をポリアミン系の硬化剤で硬化させた中性子遮蔽材が開示されている。アミン系化合物は比較的水素含有量が多いため、中性子の減速効果は向上するが、アミン部分は熱により分解し易い。又、エポキシ成分の水素含有量不足を補うため、ポリアミンの様に水素含有量は豊富だがどちらかといえば耐熱性は低い硬化剤を使用し、且つ樹脂組成物中におけるこの硬化剤の成分比率を多くする傾向にあった。従って、従来のアミン系の硬化剤により硬化した組成物と比べ、新しい高燃焼度対応の使用済核燃料を貯蔵し保管するために必要な耐久性を有する組成物の開発が望まれる。
【０００６】
【発明が解決する課題】
このように、従来は、長期にわたる新しい高燃焼度対応の使用済核燃料等の貯蔵に適した耐熱性および中性子遮蔽効果を有する遮蔽材がなかった。本発明では、耐熱性に優れ、中性子遮蔽能力を確保した中性子遮蔽材用組成物を提供することを目的とする。
【０００７】
【課題を解決するための手段】
前記課題を解決するために、本発明は、
【化９】
の構造式を有する化合物を必須の成分として含み、さらに、
【化１０】
（構造式（２）中、Ｒ₀はＣが１〜１０のアルキル基、またはＨであり、ｎ＝１〜２４）と、
【化１１】
（構造式（３）中、ｎ＝１〜８）と、
【化１２】
（構造式（７）中、Ｒ₅〜Ｒ₈は、それぞれ独立して、ＣＨ₃、Ｈ、Ｆ、Ｃｌ、Ｂｒからなる群から選択され、ｎ＝０〜２）と、
【化１３】
の構造式を有する化合物とからなる群から選択される１以上の化合物と、少なくとも１つ以上の環構造と複数のアミノ基とを有する硬化剤成分と、ホウ素化合物とを含む中性子遮蔽材用組成物を提供する。硬化剤成分が、
【化１４】
の構造式を有する化合物を含むことが好ましい。硬化剤成分が
【化１５】
と、
【化１６】
（構造式（８）中、Ｒ₉〜Ｒ₁₁は、それぞれ独立して、Ｃが１〜１８のアルキル基、またはＨである）とのうちのいずれか一つあるいはこれらの両方を含むことが好ましい。さらには、充填剤を含み、耐火材を含む中性子遮蔽材用組成物を提供する。前記耐火材として、水酸化マグネシウム、水酸化アルミニウムの少なくとも１種を含むことが好ましい。本発明は、また、中性子遮蔽材用組成物により製造された中性子遮蔽材及び中性子遮蔽容器を提供する。
【０００８】
【発明の実施の態様】
以下に、本発明の実施の態様を詳細に説明する。なお、以下に説明する実施の態様は、本発明を限定するものではない。本発明を通じて、エポキシ成分とは、エポキシ環を有する化合物（以下、エポキシ化合物という）をいい、一種類のエポキシ化合物である場合も、二種類以上のエポキシ化合物の混合物である場合も含む。硬化剤成分とは、一種類以上の硬化剤をいう。樹脂成分とは、エポキシ成分と硬化剤成分とあわせたものをいう。
【０００９】
従来のエポキシ系の中性子遮蔽材用の組成物において、特に耐熱性に問題があるのは、主に硬化剤成分として用いられるアミン成分であった。高温条件下で使用すると、硬化させた樹脂のアミン部分で結合が分解しやすいためである。しかしながら、従来の組成ではエポキシ成分の水素含有量が少ないため、それを補うために水素含有量が多く耐熱性が低いアミン系硬化剤を多く含む組成とすることで必要な水素量を確保していた。
従って、本発明においては、エポキシ成分に比較的水素含有量が多く、且つ剛直な構造を有する多官能エポキシにより高架橋密度となる化合物を用いることで高耐熱化とエポキシ成分自体の高水素含有量化を行う。また、硬化剤のアミンにも剛直な構造を有する化合物を用いるとともに樹脂組成全体に対するアミン成分の比率をも小さく押さえて、耐熱性の向上を図ることを目的とした。さらに、水素含有量の多いエポキシ成分、硬化剤成分を用い、中性子減速の効果を向上させることを目的とした。
【００１０】
本発明は、エポキシ成分と、硬化剤成分と、中性子吸収剤であるホウ素化合物と、耐火材とを含んでなる、耐熱性に優れ、中性子遮蔽効果の高い水素含有率が高い組成物である。具体的には、本発明の組成物には、硬化して樹脂としたときに熱重量分析による重量残存率９０重量％の温度が３３０℃以上、好ましくは３５０℃以上、樹脂成分全体に占める水素含有量が９．８重量％以上であることが求められる。又、以上に加えて更に詳細には、長期間高温密閉環境下での熱耐久後の硬化した樹脂の重量減少及び圧縮強度の低下が小さい程良く、例えば１９０℃×１０００ｈｒの密閉熱耐久後の重量減少率は０．５重量％以下、好ましくは０．２重量％以下、圧縮強度は低下していない、最も好ましくはむしろ上昇傾向にあることが求められる。
【００１１】
本発明のエポキシ成分には、アミン系の硬化剤を用いて硬化することができるエポキシ環を有する化合物を用いる。エポキシ成分は、一種類のエポキシ化合物でも、複数のエポキシ化合物を混合したものであってもよい。耐熱性、水素含有量増加といった所望の性能を付与することができるようにエポキシ化合物を選択する。
【００１２】
エポキシ環を複数有する化合物が特に好ましい。エポキシ成分の架橋密度を高くすることにより、耐熱性を向上させることができるからである。また、ベンゼンなどの環構造を多く含むと、強固な構造となるため、耐熱性を向上させることができる。本発明では、さらに、これらの化合物には、水素含有量が多いことが求められる。
【００１３】
環状構造としては、ベンゼン環は剛直で耐熱性にはすぐれているが、水素含有量が少ないため、ベンゼン環に水素付加した構造を含むことが好ましい。剛直な構造としては、
【化１７】
で示される構造式（１０）を有するものが好ましいが、水素含有量を考えると、
【化１８】
で示される構造式（１１）を有するものがさらに好ましい。
【００１４】
このような条件を満たすエポキシ成分として有効な化合物は、エポキシ環を多く有し、硬化剤との反応で架橋密度が高くなる化合物である。特に、環状構造を有し、且つ４官能と多官能であることから高架橋密度が期待できるという理由で、構造式（１）が好ましく用いられる。構造式（１）は、水素含有量も多く、本発明のエポキシ成分として必要な条件を満たしている。本発明の組成物においては、構造式（１）が必須のエポキシ成分として添加される。
【００１５】
さらなる耐熱性を付与するエポキシ化合物としては、構造式（３）、構造式（６）を添加することが好ましい。これらの化合物は、環構造を有し、耐熱性に優れたエポキシ化合物である。
【００１６】
さらに耐加水分解性及び耐熱性を付与するためのエポキシ化合物としては、構造式（２）を含むことが好ましい。また、水素含有量を多くするためのエポキシ化合物としては、構造式（７）で表される水素添加ビスフェノール型エポキシを含むことが好ましい。水素添加ビスフェノール型エポキシにおいては、構造式（７）中、Ｒ₅〜Ｒ₈が、メチル基で、ｎ＝０〜２である水素添加ビスフェノールＡ型エポキシを用いた場合は、単体で水素含有量と耐熱性との両方を適切に併せ持つと言った利点がある。また、構造式（７）中、Ｒ₅〜Ｒ₈が、水素で、ｎ＝０〜２である水素添加ビスフェノールＦ型エポキシは粘度が低いため、他のエポキシ成分と混合して用いる場合に有利である。さらに、構造式（９）は、水素含有量を保ち、かつ耐熱性が期待できるため、エポキシ成分にこの化合物を添加することが好ましい。
【００１７】
従って、本発明のエポキシ成分は、構造式（１）を必須の成分とし、さらに、構造式（２）、構造式（３）、構造式（６）、構造式（７）、構造式（９）のうちから選択される１以上の化合物を含んでなる。このとき、構造式（２）、構造式（３）、構造式（６）、構造式（７）、構造式（９）の全てを含んでもよく、またこれらのうちの１つを含むものであってもよい。構造式（２）、構造式（３）、構造式（６）、構造式（７）、構造式（９）のうちからいくつかを組み合わせて含む場合には、これらの化合物の全ての組み合わせが可能である。
【００１８】
例えば、本発明のエポキシ成分として、構造式（１）と構造式（２）と構造式（３）とからなる組成物を用いるとき、構造式（１）は、５０重量％〜９０重量％であることが好ましく、構造式（２）は、１０重量％〜４０重量％であることが好ましく、構造式（３）は１０重量％〜３０重量％であることが好ましい。
【００１９】
これらのエポキシ成分の組成は、樹脂成分の水素含有量が、中性子を遮蔽するのに十分な量、好ましくは、９．８重量％以上になるように決定する。中性子遮蔽材の中性子遮蔽性能は中性子遮蔽材の水素含有量（密度）と中性子遮蔽材の厚さにより決定されるが、この値は、キャスクに求められる中性子遮蔽性能とキャスクの中性子遮蔽材の設計厚さから決定される中性子遮蔽材に要求される水素含有量（密度）をもとに、中性子遮蔽材に混練される耐火材や中性子吸収材の配合量を考慮して樹脂成分に求められる水素含有量を算出した値を基準にしたものである。このとき、エポキシ成分全体において、構造式（１）の添加量は、５０重量％以上であることが好ましく、６０重量％以上９０重量％以下であることがさらに好ましい。エポキシ成分全体のうち、１０重量％以上は、構造式（１）以外のエポキシ成分を添加することが好ましい。
【００２０】
構造式（１）以外のエポキシ成分の組成については、構造式（７）で示される水素添加ビスフェノール型エポキシは、エポキシ成分全体の５０重量％以下になるように添加することが好ましく、３０重量％以下がさらに好ましい。構造式（３）は、５０重量％以下が好ましく、３０重量％以下がさらに好ましい。構造式（６）で示されるビスフェノール型エポキシは、３０重量％以下が好ましく、２０重量％以下がさらに好ましい。
【００２１】
構造式（２）の添加量は、エポキシ成分全体の４０重量％以下が好ましく、３０重量％以下がさらに好ましい。構造式（２）を多く添加しすぎると粘度が上昇してしまい、耐火材等を添加することができなくなるためである。ただし、構造式（１）と構造式（２）とを、水素添加ビスフェノールＦ型エポキシとともに用いた場合には粘度上昇が抑えられるため、構造式（２）を多量に添加する際に効果的である。例えば、構造式（２）をエポキシ成分中、４０重量％を越えて用いることも可能である。
【００２２】
本発明において、エポキシ成分と反応して架橋構造を形成する硬化剤としては、アミン系の化合物を用いる。架橋構造を多くすることで耐熱性を向上させるため、アミノ基を複数有する化合物が好ましい。さらに耐熱性を付与するために環構造を１つ以上、好ましくは２つ以上有する硬化剤成分を用いる。環構造を複数有する硬化剤成分は特に耐熱性が高いため、本発明の組成物において好適に用いられる。環構造には、ベンゼン環、シクロヘキサン環、ナフタレン環等の炭化水素の環状構造、及びその他複素環などの熱安定性の高い５又は６員環及びこれらを結合させた構造やこれらよりなる複合の環状構造等の環構造が好ましい。
【００２３】
このような硬化剤成分としては様々な文献に多数記載されており、それらをエポキシ成分のエポキシ当量との兼ね合いから化学量論的に導かれる必要配合量と水素含有量等を考慮して任意に適用可能である。特に、水素含有量と耐熱性、及び粘度等の点からメンセンジアミン、イソホロンジアミン、１，３−ジアミノシクロヘキサンなどを用いることができる。中でも、耐熱性の面からは、２つの環構造を有するアミン化合物、具体的には構造式（４）を用いることが好ましい。構造式（５）は、構造式（４）に対し、副成分として添加することができる。また、構造式（８）は少量の添加でも硬化剤として機能する、硬化促進剤的に機能する、という特徴を有し、硬化剤成分の減量に効果的である。
【００２４】
硬化剤成分が、構造式（４）を含む２種類以上の成分を含む場合、例えば、構造式（４）と構造式（５）との２種類からなる場合には、構造式（４）は、硬化剤成分全体に対して、８０重量％以下であることが好ましく、６０重量％以下がさらに好ましい。硬化剤の総添加量は、樹脂成分全体に対して３０重量％以下が好ましく、２５重量％以下がさらに好ましいが、基本的には必要配合量はエポキシ成分のエポキシ当量との兼ね合いから化学量論的に導かれる。
【００２５】
中性子吸収剤であるホウ素化合物には、炭化ホウ素、窒化ホウ素，無水ホウ酸、ホウ素鉄、灰硼石、正ホウ酸、メタホウ酸等があるが、炭化ホウ素が最も好ましい。
【００２６】
上記のホウ素化合物は粉末で用いられる。その粒度及び添加量には特に制限はない。しかし、マトリックス樹脂であるエポキシ樹脂内の分散性、中性子に対する遮蔽性を考慮すれば平均粒径は１〜２００ミクロン程度が好ましく、１０〜１００ミクロン程度がより好ましく、２０〜５０ミクロン程度が特に好ましい。一方、添加量は後述の充填剤も含めた組成物全体に対して0.５ないし２０重量％の範囲が最も好ましい。0.５重量％未満では加えたホウ素化合物の中性子遮蔽材としての効果が低く、また、２０重量％を超えた場合はホウ素化合物を均一に分散させることが困難になる。
【００２７】
本発明には充填剤として、シリカ、アルミナ、炭酸カルシウム、三酸化アンチモン、酸化チタン、B₄C、アスベスト、クレー、マイカ等の粉末の他、ガラス繊維等も用いられ、また、必要に応じ炭素繊維等を添加しても良い。更に必要に応じて、離型剤としての天然ワックス、脂肪酸の金属塩、酸アミド類、脂肪酸エステル類等、難燃剤としての塩化パラフィン、ブロムトルエン、ヘキサブロムベンゼン、三酸化アンチモン等、着色剤としてのカーボンブラック、ベンガラ等の他、シランカップリング剤、チタンカップリング剤等を添加することができる。
【００２８】
本発明に係る組成物において使用される耐火剤は、万一、火災に遭遇した場合でも、ある程度以上の中性子遮蔽能力を維持できるよう、中性子遮蔽材をある程度以上残存させることを目的としている。このような耐火材としては、水酸化マグネシウム、水酸化アルミニウムが好ましい。中でも、水酸化マグネシウムは１７０℃以上の高温でも安定に存在するため、特に好ましい。これら耐火剤の添加量は上記組成物全体中２０〜７０重量％が好ましく、３５〜６０重量％が特に好ましい。
【００２９】
本発明の組成物は、エポキシ成分とその他の添加剤とを混合後、室温に放置し、混合物が室温程度になったところで硬化剤成分を混合し、最後に耐火材を添加することによって調整する。重合は、室温でも可能だが加熱により行うことが好ましい。重合条件としては、樹脂成分の組成によっても異なるが、５０℃〜２００℃の温度条件において、１時間〜３時間加熱を行うことが好ましい。さらには、このような加熱処理は２段階で行うことが好ましく、６０℃〜９０℃で１時間〜２時間加熱した後、１２０℃〜１５０℃で、２時間から３時間加熱処理することが好ましい。
【００３０】
以上のような組成物を用いて、使用済核燃料を貯蔵・輸送するための容器である中性子遮蔽容器を製造する。このような中性子遮蔽容器、例えば、輸送用のキャスクは、公知技術を利用して製造することができる。例えば、特開平2000-9890号公報に開示されたキャスクにおいて、中性子遮蔽体を充填する個所が設けられている。このような個所に、本発明の組成物を充填することができる。
【００３１】
このようなキャスク中の遮蔽体に限定されることなく、本発明の組成物は、中性子の拡散を防止する装置や施設において、さまざまな個所に用いることができ、効果的に中性子を遮蔽することができる。
【００３２】
【実施例】
以下に、実施例を用いて本発明を詳細に説明する。なお、以下の実施例は本発明を限定する目的ではない。
【００３３】
実施例において、本発明の組成物を調製し、中性子遮蔽効果を調べた。通常は中性子遮蔽材用樹脂組成物に、耐火材として水酸化アルミニウムや水酸化マグネシウム等を全体の６０重量％程度、及び中性子吸収剤として炭化ホウ素等のホウ素化合物を全体の１重量％程度を混合して、中性子遮蔽材を作製する。しかし、ここでは樹脂成分、即ち、エポキシ成分と硬化剤成分とによる性能を評価すべく耐火材および中性子吸収剤は添加しないものを中心とした。
【００３４】
中性子遮蔽材に求められる性能としては、耐熱性（重量残存率、圧縮強度等）、耐火性、水素含有量（中性子遮蔽としての適性の判断目安として材料中の水素含有密度がある一定量以上あることが必要となる）等がある。耐火性は耐火材による部分が大であるため、中性子遮蔽材用樹脂組成物の評価としては重量残存率に見る耐熱性と水素含有量を評価した。重量残存率は、昇温時の重量変化を測定することにより、その耐熱性を評価するものである。測定にはＴＧＡを用い、熱重量減少の測定条件は室温〜600℃までを昇温速度10℃／min、窒素雰囲気下にて測定した。また、樹脂に求められる水素含有量の基準値としては樹脂単体中での水素含有量を９．８重量％程度以上とした。
【００３５】
［実施例１］
エポキシ樹脂として多官能グリシジルアミン型エポキシ樹脂（三菱瓦斯化学（株）製、ＴＥＴＲＡＤ−Ｃ（構造式（１）））５７．６３ｇと多官能脂環型エポキシ樹脂（ダイセル化学（株）製、ＥＨＰＥ３１５０（構造式（２）））１９．７２ｇを混合し、１１０℃に保持してＥＨＰＥ３１５０（固形）が溶解するまで良く攪拌した。ＥＨＰＥ３１５０溶解後室温に放置し、室温付近まで温度が低下したら硬化剤として１，３−ＢＡＣ（三菱瓦斯化学（株）製、（構造式（５）））２２．６５ｇを混合・攪拌して中性子遮蔽材用に用いる樹脂組成物とした。
上記中性子遮蔽材用樹脂組成物の水素含有量を成分分析により測定した。測定の結果、水素含有量は９．８重量％程度で基準値を満足した。
上記中性子遮蔽材用樹脂組成物を80℃×30min＋150℃×２hrで硬化させ、その硬化物の熱重量減少を測定した。測定の結果、２００℃での重量残存率９９．５重量％以上、重量残存率９０重量％の温度が３５０℃以上と良好な耐熱性、熱安定性を示した。
【００３６】
［実施例２］
エポキシ樹脂として多官能グリシジルアミン型エポキシ樹脂（ＴＥＴＲＡＤ−Ｃ（構造式（１）））５８．３１ｇと脂環型エポキシ樹脂（セロキサイド２０２１Ｐ、ダイセル化学（株）製、（構造式（３）））３．７６ｇと多官能脂環型エポキシ樹脂（ＥＨＰＥ３１５０（構造式（２）））１５．０１ｇを混合し、１１０℃に保持してＥＨＰＥ３１５０（固形）が溶解するまで良く攪拌した。ＥＨＰＥ３１５０溶解後室温に放置し、室温付近まで温度が低下したら硬化剤として１，３−ＢＡＣ（構造式（５））２２．９２ｇを混合・攪拌して中性子遮蔽材用に用いる樹脂組成物とした。
実施例１と同様に樹脂組成物中の水素含有量を測定した結果、水素含有量は９．８重量％程度で基準値を満足した。一方、上記中性子遮蔽材用樹脂組成物を80℃×30min＋150℃×２hrで硬化させ、熱重量減少を測定した結果、２００℃での重量残存率９９．５重量％以上、重量残存率９０重量％の温度が３５０℃程度と良好な耐熱性、熱安定性を示した。
【００３７】
［実施例３］
エポキシ樹脂として多官能グリシジルアミン型エポキシ樹脂（ＴＥＴＲＡＤ−Ｃ（構造式（１）））５９．８１ｇとビスフェノールＡ型エポキシ樹脂（油化シェルエポキシ（株）製、エピコート８２８（構造式（６）））２．２７ｇと多官能脂環型エポキシ樹脂（ＥＨＰＥ３１５０（構造式（２）））１５．００ｇを混合し、１１０℃に保持してＥＨＰＥ３１５０（固形）が溶解するまで良く攪拌した。ＥＨＰＥ３１５０溶解後室温に放置し、室温付近まで温度が低下したら硬化剤として１，３−ＢＡＣ（構造式（５））２２．９２ｇを混合・攪拌して中性子遮蔽材用に用いる樹脂組成物とした。
樹脂組成物中の水素含有量を測定した結果、水素含有量は９．８重量％程度で基準値を満足した。一方、上記中性子遮蔽材用樹脂組成物を80℃×30min＋150℃×２hrで硬化させ、熱重量減少を測定した結果、２００℃での重量残存率９９．５重量％以上、重量残存率９０重量％の温度が３５０℃程度と良好な耐熱性、熱安定性を示した。
【００３８】
［実施例４］
エポキシ樹脂として多官能グリシジルアミン型エポキシ樹脂（ＴＥＴＲＡＤ−Ｃ（構造式（１）））４７．９２ｇと多官能脂環型エポキシ樹脂（ＥＨＰＥ３１５０（構造式（２）））２５．００ｇを混合し、１１０℃に保持してＥＨＰＥ３１５０（固形）が溶解するまで良く攪拌した。ＥＨＰＥ３１５０溶解後室温に放置し、室温付近まで温度が低下したら硬化剤としてワンダミンＨＭ（新日本理化（株）製、（構造式（４）））２０．３１ｇと１，３−ＢＡＣ（構造式（５））６．７７ｇを予め良く混合して相溶させた混合硬化剤２７．０８ｇを混合・攪拌して中性子遮蔽材用に用いる樹脂組成物とした。
樹脂組成物中の水素含有量を測定した結果、水素含有量は９．８重量％以上で基準値を満足した。一方、上記中性子遮蔽材用樹脂組成物を80℃×30min＋150℃×２hrで硬化させ、熱重量減少を測定した結果、２００℃での重量残存率９９．５重量％以上、重量残存率９０重量％の温度が３７０℃程度と極めて良好な耐熱性、熱安定性を示した。
【００３９】
［実施例５］
エポキシ樹脂として多官能グリシジルアミン型エポキシ樹脂（ＴＥＴＲＡＤ−Ｃ（構造式（１）））４４．９４ｇと脂環型エポキシ樹脂（セロキサイド２０２１Ｐ（構造式（３）））３．１８ｇと多官能脂環型エポキシ樹脂（ＥＨＰＥ３１５０（構造式（２）））２５．００ｇを混合し、１１０℃に保持してＥＨＰＥ３１５０（固形）が溶解するまで良く攪拌した。ＥＨＰＥ３１５０溶解後室温に放置し、室温付近まで温度が低下したら硬化剤としてワンダミンＨＭ（（構造式（４）））２０．１６ｇと１，３−ＢＡＣ（構造式（５））６．７２ｇを予め良く混合して相溶させた混合硬化剤２６．８８ｇを混合・攪拌して中性子遮蔽材用に用いる樹脂組成物とした。
樹脂組成物中の水素含有量を測定した結果、水素含有量は９．８重量％程度で基準値を満足した。一方、上記中性子遮蔽材用樹脂組成物を80℃×30min＋150℃×２hrで硬化させ、熱重量減少を測定した結果、２００℃での重量残存率９９．５重量％以上、重量残存率９０重量％の温度が３７０℃以上と極めて良好な耐熱性、熱安定性を示した。
【００４０】
［実施例６］
エポキシ樹脂として多官能グリシジルアミン型エポキシ樹脂（ＴＥＴＲＡＤ−Ｃ（構造式（１）））４９．６５４ｇとビスフェノールＡ型エポキシ樹脂（エピコート８２８（構造式（６）））２．１４６ｇと多官能脂環型エポキシ樹脂（ＥＨＰＥ３１５０（構造式（２）））２２．２ｇを混合し、１１０℃に保持してＥＨＰＥ３１５０（固形）が溶解するまで良く攪拌した。ＥＨＰＥ３１５０溶解後室温に放置し、室温付近まで温度が低下したら硬化剤としてワンダミンＨＭ（（構造式（４）））１５．６ｇと１，３−ＢＡＣ（構造式（５））１０．４ｇを予め良く混合して相溶させた混合硬化剤２６ｇを混合・攪拌して中性子遮蔽材用に用いる樹脂組成物とした。
樹脂組成物中の水素含有量を測定した結果、水素含有量は９．８重量％程度で基準値を満足した。一方、上記中性子遮蔽材用樹脂組成物を80℃×30min＋150℃×２hrで硬化させ、熱重量減少を測定した結果、２００℃での重量残存率９９．５重量％以上、重量残存率９０重量％の温度が３７０℃以上と極めて良好な耐熱性、熱安定性を示した。
【００４１】
［実施例７］
エポキシ樹脂として多官能グリシジルアミン型エポキシ樹脂（ＴＥＴＲＡＤ−Ｃ（構造式（１）））５０．５５ｇと脂環型エポキシ樹脂（セロキサイド２０２１Ｐ（構造式（３）））２０．６５ｇに、硬化剤としてワンダミンＨＭ（構造式（４））２１．６ｇと１，３−ＢＡＣ（構造式（５））７．２ｇを予め良く混合して相溶させた混合硬化剤２８．８ｇを混合・攪拌して中性子遮蔽材用に用いる樹脂組成物とした。
樹脂組成物中の水素含有量を測定した結果、水素含有量は９．８重量％以上で基準値を満足した。一方、上記中性子遮蔽材用樹脂組成物を80℃×30min＋150℃×２hrで硬化させ、熱重量減少を測定した結果、２００℃での重量残存率９９．５重量％以上、重量残存率９０重量％の温度が３４０℃程度と良好な耐熱性、熱安定性を示した。
【００４２】
［実施例８］
エポキシ樹脂として多官能グリシジルアミン型エポキシ樹脂（ＴＥＴＲＡＤ−Ｃ（構造式（１）））５７．１７ｇとビスフェノールＡ型エポキシ樹脂（エピコート８２８（構造式（６）））１４．２ｇに、硬化剤としてワンダミンＨＭ（構造式（４））２１．４７ｇと１，３−ＢＡＣ（構造式（５））７．１６ｇを予め良く混合して相溶させた混合硬化剤２８．６３ｇを混合・攪拌して中性子遮蔽材用に用いる樹脂組成物とした。
樹脂組成物中の水素含有量を測定した結果、水素含有量は９．８重量％程度で基準値を満足した。一方、上記中性子遮蔽材用樹脂組成物を80℃×30min＋150℃×２hrで硬化させ、熱重量減少を測定した結果、２００℃での重量残存率９９．５重量％以上、重量残存率９０重量％の温度が３４０℃程度と良好な耐熱性、熱安定性を示した。
【００４３】
［実施例９］
エポキシ樹脂として多官能グリシジルアミン型エポキシ樹脂（ＴＥＴＲＡＤ−Ｃ（構造式（１）））６０．４４ｇと脂環型エポキシ樹脂（セロキサイド２０２１Ｐ（構造式（３）））１５．７８ｇに、硬化剤として１，３−ＢＡＣ（構造式（５））２３．７８ｇを混合・攪拌して中性子遮蔽材用に用いる樹脂組成物とした。
樹脂組成物中の水素含有量を測定した結果、水素含有量は９．８重量％程度で基準値を満足した。一方、上記中性子遮蔽材用樹脂組成物を80℃×30min＋150℃×２hrで硬化させ、熱重量減少を測定した結果、２００℃での重量残存率９９．５重量％以上、重量残存率９０重量％の温度が３３０℃以上と良好な耐熱性、熱安定性を示した。
【００４４】
［実施例１０］
エポキシ樹脂として多官能グリシジルアミン型エポキシ樹脂（ＴＥＴＲＡＤ−Ｃ（構造式（１）））３９．２８ｇと水添ビスフェノールＡ型エポキシ樹脂（油化シェルエポキシ（株）製、ＹＬ６６６３（構造式（７）））１０．００ｇと多官能脂環型エポキシ樹脂（ＥＨＰＥ３１５０（構造式（２）））２５．００ｇを混合し、１１０℃に保持してＥＨＰＥ３１５０（固形）が溶解するまで良く攪拌した。ＥＨＰＥ３１５０溶解後室温に放置し、室温付近まで温度が低下したら硬化剤としてワンダミンＨＭ（（構造式（４）））１９．２９ｇと１，３−ＢＡＣ（構造式（５））６．４３ｇを予め良く混合して相溶させた混合硬化剤２５．７２ｇを混合・攪拌して中性子遮蔽材用に用いる樹脂組成物とした。
樹脂組成物中の水素含有量を測定した結果、水素含有量は９．８重量％以上（９．９重量％程度以上）で基準値を上回り満足した。一方、上記中性子遮蔽材用樹脂組成物を80℃×30min＋150℃×２hrで硬化させ、熱重量減少を測定した結果、２００℃での重量残存率９９．５重量％以上、重量残存率９０重量％の温度が３７０℃程度と極めて良好な耐熱性、熱安定性を示した。
【００４５】
［実施例１１］
エポキシ樹脂として多官能グリシジルアミン型エポキシ樹脂（ＴＥＴＲＡＤ−Ｃ（構造式（１）））４７．９２ｇと多官能脂環型エポキシ樹脂（ＥＨＰＥ３１５０（構造式（２）））２５．００ｇを混合し、１１０℃に保持してＥＨＰＥ３１５０（固形）が溶解するまで良く攪拌した。ＥＨＰＥ３１５０溶解後室温に放置し、室温付近まで温度が低下したら硬化剤としてワンダミンＨＭ（（構造式（４）））２０．１ｇと１，３−ＢＡＣ（構造式（５））６．７ｇとイミダゾール化合物（構造式（８））０．２７ｇを予め良く混合して相溶させた混合硬化剤２７．０７ｇを混合・攪拌して中性子遮蔽材用に用いる樹脂組成物とした。
樹脂組成物中の水素含有量を測定した結果、水素含有量は９．８重量％以上で基準値を満足した。一方、上記中性子遮蔽材用樹脂組成物を80℃×30min＋150℃×２hrで硬化させ、熱重量減少を測定した結果、２００℃での重量残存率９９．５重量％以上、重量残存率９０重量％の温度が３７０℃以上と極めて良好な耐熱性、熱安定性を示した。
【００４６】
［実施例１２］
ここでは、中性子吸収剤を混合した中性子遮蔽材を評価した。エポキシ樹脂として多官能グリシジルアミン型エポキシ樹脂（ＴＥＴＲＡＤ−Ｃ（構造式（１）））４９．６５４ｇとビスフェノールＡ型エポキシ樹脂（エピコート８２８（構造式（６）））２．１４６ｇと多官能脂環型エポキシ樹脂（ＥＨＰＥ３１５０（構造式（２）））２２．２ｇを混合し、１１０℃に保持してＥＨＰＥ３１５０（固形）が溶解するまで良く攪拌した。ＥＨＰＥ３１５０溶解後室温に放置し、室温付近まで温度が低下したら硬化剤としてワンダミンＨＭ（（構造式（４）））１５．６ｇと１，３−ＢＡＣ（構造式（５））１０．４ｇを予め良く混合して相溶させた混合硬化剤２６ｇを混合・攪拌した。これに水酸化マグネシウムを１４６．５ｇと炭化ホウ素３．５ｇを混合・攪拌して中性子遮蔽材用組成物とした。中性子遮蔽材に求められる水素含有量の目安としては、水素含有密度が０．０９６ｇ／cm³以上であるが、調製した中性子遮蔽材組成物の水素含有密度を測定した結果、０．０９６ｇ／cm³以上で基準値を満足した。一方、上記中性子遮蔽材用樹脂組成物を80℃×30min＋150℃×２hrで硬化させ、熱重量減少を測定した結果、２００℃での重量残存率９９．５重量％以上、重量残存率９０重量％の温度が３７０℃以上と極めて良好な耐熱性、熱安定性を示した。
【００４７】
次に比較例として、従来から用いられてきた組成物による中性子遮蔽材の性能を評価した。実施例と同様に、耐火材、中性子吸収剤は添加しなかった。また、実施例と同様に、水素含有量は成分分析により、熱重量減少はＴＧＡで測定することにより求めた。
【００４８】
［比較例１］
エポキシ樹脂としてビスフェノールＡ型エポキシ樹脂（エピコート８２８（構造式（６）））とポリアミン系の硬化剤を１：１（化学量論的に等量となる）の割合で混合・攪拌して中性子遮蔽材用に用いる樹脂組成物とした。ポリアミン系の硬化剤は、本発明の組成物に用いられる物と異なり、耐熱性の高い剛直な構造を有しておらず、又、その配合量も比率として大きなものとなっている。
実施例１と同様の方法にて樹脂組成物中の水素含有量を測定した結果、水素含有量は９．８重量％以上で基準値を満足した。一方、上記中性子遮蔽材用樹脂組成物を80℃×30min＋150℃×２hrで硬化させ、熱重量減少を測定した結果、２００℃での重量残存率９９重量％以下、重量残存率９０重量％の温度が３００℃以下であり、実施例の一群と比較して耐熱性、熱安定性は劣った。この組成系は従来から使用されている中性子遮蔽材用の樹脂組成物と同様の系を模擬したものだが、比較例１は水素含有量の点からは適性があるが、耐熱性、熱安定性的には実施例の一群と比較して低い値であり、実施例１〜１２で作製した中性子遮蔽材は、耐熱性、熱安定性的に優れていることがわかる。
【００４９】
［比較例２］
エポキシ樹脂としてビスフェノールＡ型エポキシ樹脂（エピコート８２８（構造式（６）））８１．４ｇと、硬化剤としてイソホロンジアミン１８．６ｇを良く攪拌して中性子遮蔽材用に用いる樹脂組成物とした。
樹脂組成物中の水素含有量を測定した結果、水素含有量は８．２重量％以下で基準値を大きく下回り未達となった。一方、上記中性子遮蔽材用樹脂組成物を80℃×30min＋150℃×２hrで硬化させ、熱重量減少を測定した結果、２００℃での重量残存率９９．５重量％程度、重量残存率９０重量％の温度が３５０℃程度と耐熱性、熱安定性は良かった。
この組成系は耐熱性、熱安定性的には良好だが、実施例の一群と比較して水素含有量の点から中性子遮蔽材用樹脂組成物としては不適であった。
【００５０】
［比較例３］
エポキシ樹脂として多官能グリシジルアミン型エポキシ樹脂（ＴＥＴＲＡＤ−Ｃ（構造式（１）））とポリアミン系の硬化剤を１：１（化学量論的に等量となる）の割合で混合・攪拌して中性子遮蔽材用に用いる樹脂組成物とした。
樹脂組成物中の水素含有量を測定した結果、水素含有量は９．８重量％以上（１０重量％程度以上）で基準値を上回り満足した。一方、上記中性子遮蔽材用樹脂組成物を80℃×30min＋150℃×２hrで硬化させ、熱重量減少を測定した結果、２００℃での重量残存率９９．０重量％以下、重量残存率９０重量％の温度が２７０℃以下であり、実施例の一群と比較して耐熱性、熱安定性が劣った。
【００５１】
［比較例４］
エポキシ樹脂としてポリプロピレングリコールの両末端のＯＨをそれぞれグリシジルエーテルに置換した構造を持つエポキシ樹脂（エポキシ等量１９０）８１．７ｇと、硬化剤としてイソホロンジアミン１８．３ｇを良く攪拌して中性子遮蔽材用に用いる樹脂組成物とした。
樹脂組成物中の水素含有量を測定した結果、水素含有量は９．８重量％以上で基準値を満足した。一方、上記中性子遮蔽材用樹脂組成物を80℃×30min＋150℃×２hrで硬化させ、熱重量減少を測定した結果、２００℃での重量残存率９９．５重量％以下、重量残存率９０重量％の温度が２５０℃程度未満であり、実施例の一群と比較して耐熱性、熱安定性が極めて劣った。
【００５２】
［比較例５］
エポキシ樹脂として１，６ヘキサンジグリシジルエーテル（エポキシ等量１５５）７８．５ｇと、硬化剤としてイソホロンジアミン２１．５ｇを良く攪拌して中性子遮蔽材用に用いる樹脂組成物とした。本発明の組成物に用いるエポキシ化合物が環状構造を有するエポキシであるのに対し、１，６ヘキサンジグリシジルエーテルは、環状構造を有しない脂肪族鎖状構造のエポキシであるといった点で異なる。
樹脂組成物中の水素含有量を測定した結果、水素含有量は９．８重量％以上で基準値を満足した。一方、上記中性子遮蔽材用樹脂組成物を80℃×30min＋150℃×２hrで硬化させ、熱重量減少を測定した結果、２００℃での重量残存率９９．５重量％以下、重量残存率９０重量％の温度が３００℃未満であり、実施例の一群と比較して耐熱性、熱安定性が劣った。
【００５３】
［比較例６］
ここでは、従来型の樹脂成分に中性子吸収剤を添加して評価した。エポキシ樹脂として、ビスフェノールＡ型エポキシ樹脂（エピコート８２８（構造式（６）））５０ｇとポリアミン系の硬化剤５０ｇ（化学量論的に等量となる比率）を混合・攪拌したものに水酸化マグネシウムを１４６．５ｇと炭化ホウ素３．５ｇを混合・攪拌して中性子遮蔽材用組成物とした。
中性子遮蔽材に求められる水素含有量の目安としては、水素含有密度が０．０９６ｇ／cm³以上であるが、調製した中性子遮蔽材組成物の水素含有密度を測定した結果、０．０９６ｇ／cm³以上で基準値を満足した。一方、上記中性子遮蔽材用樹脂組成物を80℃×30min＋150℃×２hrで硬化させ、熱重量減少を測定した結果、２００℃での重量残存率９９重量％以下、重量残存率９０重量％の温度が３００℃以下であり、実施例の一群と比較して耐熱性、熱安定性は劣った。又、上記硬化物を密閉容器に封入後、１９０℃×１０００ｈｒの耐熱耐久試験を行った。圧縮強度は試験前に比べ３割以上低下し、高温環境下での耐久性は低いものとなった。
この組成系は、従来から使用されている中性子遮蔽材用組成物と同様の系を模擬したものである。比較例６の組成物は水素含有量の点からは適性があるが、耐熱性、熱安定性的には実施例１２の本発明の組成物と比較して低い値であり、本発明の組成物は耐熱性、熱安定性的に優れていることがわかる。
【００５４】
【発明の効果】
本発明の中性子遮蔽用材料は、耐熱性の向上したエポキシ樹脂および硬化剤を用いて、耐熱性が良く、また中性子遮蔽能力も確保している。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a composition for a neutron shielding material. Further, the present invention relates to a composition for an epoxy resin-based neutron shielding material which is a material applied to a cask which is a container for storing and transporting spent nuclear fuel, has improved heat resistance and ensures neutron shielding properties.
[0002]
[Prior art]
Nuclear fuel used in a nuclear facility such as a nuclear power plant is usually transferred to a reprocessing plant for reprocessing. However, at present, the amount of spent nuclear fuel generated exceeds the reprocessing capacity, and therefore, there is a need to store spent nuclear fuel for a long period of time. At this time, the spent nuclear fuel is cooled to a radioactivity level suitable for transportation, and then transported in a cask. At this stage, radiation such as neutrons continues to be emitted. Neutrons are high in energy and generate gamma rays, causing serious damage to the human body. Therefore, it is necessary to develop materials that reliably shield these neutrons.
[0003]
Neutrons are known to be absorbed by boron, but in order for boron to absorb neutrons, it is necessary to slow down the neutrons. It is known that hydrogen is the most suitable material for decelerating neutrons. Thus, the composition for a neutron shielding material needs to contain many boron and hydrogen atoms.
In addition, spent nuclear fuel, which is a source of neutrons, generates decay heat, so if it is sealed for transportation and storage, it generates heat and becomes high temperature. Although this maximum temperature varies depending on the type of spent nuclear fuel, it is said that the temperature in the cask reaches about 200 ° C. in the spent nuclear fuel corresponding to high burnup. Therefore, for use as a neutron shielding material, it is desirable to be able to withstand about 60 years, which is a storage standard for spent nuclear fuel, under such a high temperature condition.
[0004]
For this reason, use of a substance having a high hydrogen density, particularly water, has been proposed as a shielding material, and a part thereof is also put into practical use. However, since water is a liquid, it is difficult to handle and is not particularly suitable for casks intended for transportation and storage. Further, since the inside of the cask reaches 100 ° C. or higher, there is a problem that it is difficult to suppress boiling.
[0005]
Therefore, conventionally, a resin composition has been used as one material of the neutron shielding material, and an epoxy resin has been used as one of the resin compositions. In general, the hydrogen content and heat resistance of a resin composition are in a reciprocal relationship, and those having a high hydrogen content tend to have low heat resistance, and those having high heat resistance tend to have a low hydrogen content. Epoxy resins are excellent in heat resistance and curability, but tend to have a low hydrogen content, which is essential for slowing down neutrons. The method of using and supplementing was common.
JP-A-6-148388 discloses a composition for a neutron shielding material that uses a polyfunctional amine-based epoxy resin to reduce viscosity and improve workability at room temperature, and has an excellent pot life. . Japanese Patent Application Laid-Open No. 9-176496 discloses a neutron shielding material obtained by curing a composition made of an acrylic resin, an epoxy resin, a silicone resin or the like with a polyamine curing agent. Since the amine compound has a relatively high hydrogen content, the neutron moderating effect is improved, but the amine portion is easily decomposed by heat. Also, in order to compensate for the insufficient hydrogen content of the epoxy component, a curing agent with abundant hydrogen content such as polyamine but rather low heat resistance is used, and the component ratio of this curing agent in the resin composition is changed. There was a tendency to increase. Therefore, it is desired to develop a composition having durability necessary for storing and storing a new high burnup compatible spent nuclear fuel as compared with a composition cured with a conventional amine-based curing agent.
[0006]
[Problems to be solved by the invention]
Thus, conventionally, there has been no shielding material having a heat resistance and a neutron shielding effect suitable for storage of spent nuclear fuel corresponding to a new high burnup over a long period of time. An object of the present invention is to provide a composition for a neutron shielding material that has excellent heat resistance and ensures neutron shielding ability.
[0007]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides:
[Chemical 9]
A compound having the following structural formula as an essential component;
[Chemical Formula 10]
(In the structural formula (2), R ₀ C is an alkyl group of 1 to 10 or H, and n = 1 to 24),
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(In structural formula (3), n = 1 to 8)
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(In the structural formula (7), R _Five ~ R ₈ Are each independently CH _Three , H, F, Cl, Br, n = 0-2),
Embedded image
A composition for a neutron shielding material comprising one or more compounds selected from the group consisting of compounds having the structural formula: a curing agent component having at least one ring structure and a plurality of amino groups, and a boron compound. Offer things. Hardener component is
Embedded image
It is preferable to include a compound having the following structural formula. Hardener component is
Embedded image
When,
Embedded image
(In structural formula (8), R ₉ ~ R ₁₁ Each independently includes C or an alkyl group having 1 to 18 or H), or preferably both. Furthermore, the composition for neutron shielding materials containing a filler and containing a refractory material is provided. The refractory material preferably contains at least one of magnesium hydroxide and aluminum hydroxide. This invention also provides the neutron shielding material and neutron shielding container which were manufactured with the composition for neutron shielding materials.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail. Note that the embodiments described below do not limit the present invention. Throughout the present invention, the epoxy component refers to a compound having an epoxy ring (hereinafter referred to as an epoxy compound), and includes a case of one type of epoxy compound and a case of a mixture of two or more types of epoxy compounds. A hardening | curing agent component means one or more types of hardening | curing agents. The resin component means a combination of an epoxy component and a curing agent component.
[0009]
In the conventional composition for epoxy-based neutron shielding materials, it is an amine component mainly used as a hardener component that has a problem in heat resistance. This is because, when used under high temperature conditions, the bond is easily decomposed at the amine portion of the cured resin. However, since the hydrogen content of the epoxy component is low in the conventional composition, the necessary hydrogen amount is secured by making the composition containing a large amount of amine-based curing agent with a high hydrogen content and low heat resistance to compensate for it. It was.
Therefore, in the present invention, by using a compound having a relatively high hydrogen content in the epoxy component and a high crosslink density due to a polyfunctional epoxy having a rigid structure, high heat resistance and high hydrogen content of the epoxy component itself are achieved. Do. Another object of the present invention is to improve the heat resistance by using a compound having a rigid structure for the amine of the curing agent and suppressing the ratio of the amine component to the entire resin composition to be small. Furthermore, an epoxy component and a curing agent component with a high hydrogen content were used to improve the effect of neutron moderation.
[0010]
The present invention is a composition having an excellent heat resistance and a high hydrogen content with a high neutron shielding effect, comprising an epoxy component, a curing agent component, a boron compound as a neutron absorber, and a refractory material. Specifically, in the composition of the present invention, when cured into a resin, the temperature at a weight residual ratio of 90% by thermogravimetric analysis is 330 ° C. or higher, preferably 350 ° C. or higher. It is calculated | required that content is 9.8 weight% or more. In addition to the above, more specifically, the smaller the decrease in the weight of the cured resin and the decrease in the compressive strength after heat endurance in a high temperature sealed environment for a long period of time, the better, for example, after 190 ° C. × 1000 hr The weight reduction rate is 0.5% by weight or less, preferably 0.2% by weight or less, and the compressive strength is not lowered, and most preferably, it tends to increase.
[0011]
For the epoxy component of the present invention, a compound having an epoxy ring that can be cured using an amine-based curing agent is used. The epoxy component may be a single type of epoxy compound or a mixture of a plurality of epoxy compounds. The epoxy compound is selected so that desired performance such as heat resistance and increased hydrogen content can be imparted.
[0012]
A compound having a plurality of epoxy rings is particularly preferred. This is because the heat resistance can be improved by increasing the crosslinking density of the epoxy component. Moreover, since it will become a firm structure when many ring structures, such as benzene, are included, heat resistance can be improved. In the present invention, these compounds are further required to have a high hydrogen content.
[0013]
As the cyclic structure, the benzene ring is rigid and excellent in heat resistance, but since the hydrogen content is small, it is preferable to include a structure in which hydrogen is added to the benzene ring. As a rigid structure,
Embedded image
Those having the structural formula (10) shown below are preferred, but considering the hydrogen content,
Embedded image
What has structural formula (11) shown by these is further more preferable.
[0014]
A compound effective as an epoxy component satisfying such conditions is a compound having a large number of epoxy rings and having a high crosslinking density by reaction with a curing agent. In particular, the structural formula (1) is preferably used because it has a cyclic structure and can be expected to have a high crosslinking density because it is tetrafunctional and polyfunctional. Structural formula (1) has a high hydrogen content and satisfies the conditions necessary for the epoxy component of the present invention. In the composition of the present invention, structural formula (1) is added as an essential epoxy component.
[0015]
As an epoxy compound imparting further heat resistance, it is preferable to add structural formula (3) and structural formula (6). These compounds are epoxy compounds having a ring structure and excellent heat resistance.
[0016]
Further, the epoxy compound for imparting hydrolysis resistance and heat resistance preferably contains the structural formula (2). The epoxy compound for increasing the hydrogen content preferably includes a hydrogenated bisphenol type epoxy represented by the structural formula (7). In the hydrogenated bisphenol type epoxy, R in the structural formula (7) _Five ~ R ₈ However, when a hydrogenated bisphenol A type epoxy having a methyl group and n = 0 to 2 is used, there is an advantage that both the hydrogen content and the heat resistance are appropriately combined. In Structural Formula (7), R _Five ~ R ₈ However, hydrogenated bisphenol F-type epoxy having n = 0 to 2 having a low viscosity is advantageous when used in combination with other epoxy components. Furthermore, since the structural formula (9) maintains the hydrogen content and can be expected to have heat resistance, it is preferable to add this compound to the epoxy component.
[0017]
Therefore, the epoxy component of the present invention has the structural formula (1) as an essential component, and further includes the structural formula (2), the structural formula (3), the structural formula (6), the structural formula (7), and the structural formula (9). 1) one or more compounds selected from. At this time, the structural formula (2), the structural formula (3), the structural formula (6), the structural formula (7), and the structural formula (9) may be included, or one of them may be included. There may be. When some of the structural formula (2), structural formula (3), structural formula (6), structural formula (7), and structural formula (9) are included in combination, all combinations of these compounds are Is possible.
[0018]
For example, when a composition comprising the structural formula (1), the structural formula (2), and the structural formula (3) is used as the epoxy component of the present invention, the structural formula (1) is 50 wt% to 90 wt%. Preferably, the structural formula (2) is preferably 10% by weight to 40% by weight, and the structural formula (3) is preferably 10% by weight to 30% by weight.
[0019]
The composition of these epoxy components is determined so that the hydrogen content of the resin component is sufficient to shield neutrons, preferably 9.8% by weight or more. The neutron shielding performance of a neutron shielding material is determined by the hydrogen content (density) of the neutron shielding material and the thickness of the neutron shielding material. This value depends on the neutron shielding performance required for the cask and the design of the neutron shielding material for the cask. Based on the hydrogen content (density) required for the neutron shielding material determined from the thickness, the hydrogen required for the resin component in consideration of the blending amount of refractory material and neutron absorbing material mixed with the neutron shielding material This is based on the calculated value of the content. At this time, in the entire epoxy component, the amount of structural formula (1) added is preferably 50% by weight or more, and more preferably 60% by weight or more and 90% by weight or less. It is preferable to add an epoxy component other than the structural formula (1) to 10% by weight or more of the entire epoxy component.
[0020]
Regarding the composition of the epoxy component other than the structural formula (1), the hydrogenated bisphenol-type epoxy represented by the structural formula (7) is preferably added so as to be 50% by weight or less of the entire epoxy component, and 30% by weight. The following is more preferable. The structural formula (3) is preferably 50% by weight or less, and more preferably 30% by weight or less. The bisphenol type epoxy represented by the structural formula (6) is preferably 30% by weight or less, and more preferably 20% by weight or less.
[0021]
The amount of structural formula (2) added is preferably 40% by weight or less, more preferably 30% by weight or less, based on the entire epoxy component. This is because when too much of the structural formula (2) is added, the viscosity increases, and it becomes impossible to add a refractory material or the like. However, when the structural formula (1) and the structural formula (2) are used together with the hydrogenated bisphenol F-type epoxy, the increase in viscosity is suppressed, which is effective when a large amount of the structural formula (2) is added. is there. For example, the structural formula (2) can be used in an amount exceeding 40% by weight in the epoxy component.
[0022]
In the present invention, an amine compound is used as a curing agent that reacts with the epoxy component to form a crosslinked structure. In order to improve heat resistance by increasing the number of cross-linked structures, compounds having a plurality of amino groups are preferred. Further, in order to impart heat resistance, a curing agent component having one or more, preferably two or more ring structures is used. Since the curing agent component having a plurality of ring structures has particularly high heat resistance, it is preferably used in the composition of the present invention. The ring structure includes hydrocarbon cyclic structures such as a benzene ring, cyclohexane ring, naphthalene ring, and other 5- or 6-membered rings having high thermal stability such as heterocycles, and a structure in which these are combined or a composite of these. A ring structure such as a cyclic structure is preferred.
[0023]
A large number of such hardener components are described in various documents, and they are arbitrarily determined in consideration of the necessary blending amount and hydrogen content, etc. that are derived stoichiometrically from the balance with the epoxy equivalent of the epoxy component. Applicable. In particular, mensendiamine, isophoronediamine, 1,3-diaminocyclohexane, and the like can be used from the viewpoints of hydrogen content, heat resistance, viscosity, and the like. Among these, from the viewpoint of heat resistance, it is preferable to use an amine compound having two ring structures, specifically, the structural formula (4). Structural formula (5) can be added as a subcomponent to structural formula (4). Further, the structural formula (8) has the characteristics that it functions as a curing agent and functions as a curing accelerator even when added in a small amount, and is effective in reducing the amount of the curing agent component.
[0024]
When the curing agent component includes two or more kinds of components including the structural formula (4), for example, when the hardener component includes two types of the structural formula (4) and the structural formula (5), the structural formula (4) is The content of the curing agent component is preferably 80% by weight or less, and more preferably 60% by weight or less. The total addition amount of the curing agent is preferably 30% by weight or less, more preferably 25% by weight or less based on the entire resin component, but basically the required blending amount is stoichiometric from the balance with the epoxy equivalent of the epoxy component. Guided.
[0025]
Boron compounds that are neutron absorbers include boron carbide, boron nitride, boric anhydride, boron iron, perovskite, orthoboric acid, metaboric acid, and the like, with boron carbide being most preferred.
[0026]
The boron compound is used as a powder. There is no restriction | limiting in particular in the particle size and addition amount. However, considering the dispersibility in the epoxy resin as the matrix resin and the shielding property against neutrons, the average particle size is preferably about 1 to 200 microns, more preferably about 10 to 100 microns, and particularly preferably about 20 to 50 microns. . On the other hand, the addition amount is most preferably in the range of 0.5 to 20% by weight based on the whole composition including the filler described later. If it is less than 0.5% by weight, the effect of the added boron compound as a neutron shielding material is low, and if it exceeds 20% by weight, it becomes difficult to uniformly disperse the boron compound.
[0027]
In the present invention, as a filler, silica, alumina, calcium carbonate, antimony trioxide, titanium oxide, B _Four In addition to powders such as C, asbestos, clay and mica, glass fibers and the like are also used, and carbon fibers and the like may be added as necessary. Furthermore, as necessary, natural wax as a mold release agent, fatty acid metal salts, acid amides, fatty acid esters, etc., chlorinated paraffin, bromotoluene, hexabromobenzene, antimony trioxide, etc. as flame retardants as colorants In addition to carbon black, bengara, etc., silane coupling agents, titanium coupling agents and the like can be added.
[0028]
The refractory agent used in the composition according to the present invention is intended to leave a neutron shielding material to a certain extent so that a neutron shielding capability of a certain degree or more can be maintained even if a fire is encountered. As such a refractory material, magnesium hydroxide and aluminum hydroxide are preferable. Among these, magnesium hydroxide is particularly preferable because it exists stably even at a high temperature of 170 ° C. or higher. The amount of the refractory added is preferably 20 to 70% by weight, particularly preferably 35 to 60% by weight, based on the whole composition.
[0029]
The composition of the present invention is prepared by mixing the epoxy component and other additives, leaving it at room temperature, mixing the curing agent component when the mixture reaches about room temperature, and finally adding a refractory material. . Polymerization is possible at room temperature, but is preferably performed by heating. Although it changes with composition of a resin component as superposition | polymerization conditions, it is preferable to heat for 1 hour-3 hours in 50 degreeC-200 degreeC temperature conditions. Furthermore, such heat treatment is preferably performed in two stages, and after heating at 60 ° C. to 90 ° C. for 1 hour to 2 hours, heat treatment is preferably performed at 120 ° C. to 150 ° C. for 2 hours to 3 hours. .
[0030]
A neutron shielding container, which is a container for storing and transporting spent nuclear fuel, is manufactured using the composition as described above. Such a neutron shielding container, for example, a transport cask, can be manufactured using a known technique. For example, in a cask disclosed in Japanese Patent Application Laid-Open No. 2000-9890, a portion for filling a neutron shield is provided. Such a location can be filled with the composition of the present invention.
[0031]
Without being limited to such a shield in a cask, the composition of the present invention can be used at various locations in devices and facilities that prevent neutron diffusion, and effectively shields neutrons. Can do.
[0032]
【Example】
Hereinafter, the present invention will be described in detail with reference to examples. The following examples are not intended to limit the present invention.
[0033]
In the examples, the composition of the present invention was prepared and the neutron shielding effect was examined. Normally, about 60% by weight of aluminum hydroxide or magnesium hydroxide as a refractory material and about 1% by weight of boron compound such as boron carbide as a neutron absorber are mixed with a resin composition for a neutron shielding material. Then, a neutron shielding material is produced. However, here, in order to evaluate the performance of the resin component, that is, the epoxy component and the curing agent component, the refractory material and the neutron absorber are not added.
[0034]
The performance required for neutron shielding materials includes heat resistance (weight residual ratio, compressive strength, etc.), fire resistance, hydrogen content (the hydrogen content density in the material is a certain amount or more as a measure of suitability for neutron shielding) Is necessary). Since the fire resistance largely depends on the refractory material, the evaluation of the resin composition for neutron shielding material was based on the heat resistance and hydrogen content as seen in the weight residual ratio. The weight residual ratio is to evaluate the heat resistance by measuring the weight change at the time of temperature rise. TGA was used for the measurement, and the measurement conditions for thermogravimetry were measured from room temperature to 600 ° C. under a temperature rising rate of 10 ° C./min in a nitrogen atmosphere. Further, as a reference value for the hydrogen content required for the resin, the hydrogen content in the resin alone was set to about 9.8% by weight or more.
[0035]
[Example 1]
As the epoxy resin, 57.63 g of a polyfunctional glycidylamine type epoxy resin (manufactured by Mitsubishi Gas Chemical Co., Ltd., TETRAD-C (structural formula (1))) and a polyfunctional alicyclic epoxy resin (manufactured by Daicel Chemical Industries, Ltd., EHPE3150) (Structural formula (2))) 19.72 g was mixed and kept at 110 ° C. and stirred well until EHPE3150 (solid) was dissolved. After dissolving EHPE3150, it is allowed to stand at room temperature. When the temperature drops to near room temperature, 22.65 g of 1,3-BAC (Mitsubishi Gas Chemical Co., Ltd. (Structural Formula (5))) is mixed and stirred as a curing agent, and neutrons are mixed. It was set as the resin composition used for shielding materials.
The hydrogen content of the resin composition for neutron shielding material was measured by component analysis. As a result of the measurement, the hydrogen content was about 9.8% by weight and satisfied the standard value.
The neutron shielding material resin composition was cured at 80 ° C. × 30 min + 150 ° C. × 2 hr, and the thermogravimetric decrease of the cured product was measured. As a result of the measurement, the temperature with a weight residual ratio of 99.5% by weight or more at 200 ° C. and a weight residual ratio of 90% by weight was 350 ° C. or higher, indicating good heat resistance and thermal stability.
[0036]
[Example 2]
58.31 g of polyfunctional glycidylamine type epoxy resin (TETRAD-C (structural formula (1))) and an alicyclic epoxy resin (Celoxide 2021P, manufactured by Daicel Chemical Industries, Ltd. (structural formula (3))) 3.76 g and 15.01 g of a polyfunctional alicyclic epoxy resin (EHPE3150 (structural formula (2))) were mixed, and the mixture was kept at 110 ° C. and stirred well until EHPE3150 (solid) was dissolved. After dissolving EHPE3150, it was allowed to stand at room temperature. When the temperature dropped to near room temperature, 22.92 g of 1,3-BAC (structural formula (5)) as a curing agent was mixed and stirred to obtain a resin composition used for a neutron shielding material. .
As a result of measuring the hydrogen content in the resin composition in the same manner as in Example 1, the hydrogen content was about 9.8% by weight and satisfied the standard value. On the other hand, the resin composition for neutron shielding material was cured at 80 ° C. × 30 min + 150 ° C. × 2 hr, and the thermal weight loss was measured. As a result, the residual weight ratio at 200 ° C. was 99.5% by weight or more, and the residual weight ratio was 90% by weight. The temperature was about 350 ° C., indicating good heat resistance and thermal stability.
[0037]
[Example 3]
59.81 g of polyfunctional glycidylamine type epoxy resin (TETRAD-C (structural formula (1))) and bisphenol A type epoxy resin (manufactured by Yuka Shell Epoxy Co., Ltd., Epicoat 828) (epoxy formula (6)) ) 2.27 g and 15.00 g of a polyfunctional alicyclic epoxy resin (EHPE3150 (structural formula (2))) were mixed and kept at 110 ° C. until the EHPE3150 (solid) was dissolved. After dissolving EHPE3150, it was allowed to stand at room temperature. When the temperature dropped to near room temperature, 22.92 g of 1,3-BAC (structural formula (5)) as a curing agent was mixed and stirred to obtain a resin composition used for a neutron shielding material. .
As a result of measuring the hydrogen content in the resin composition, the hydrogen content was about 9.8% by weight and satisfied the standard value. On the other hand, the resin composition for neutron shielding material was cured at 80 ° C. × 30 min + 150 ° C. × 2 hr, and the thermal weight loss was measured. As a result, the weight residual rate at 200 ° C. was 99.5% by weight or more and the weight residual rate 90% by weight. The temperature was about 350 ° C., indicating good heat resistance and thermal stability.
[0038]
[Example 4]
As the epoxy resin, 47.92 g of a polyfunctional glycidylamine type epoxy resin (TETRAD-C (structural formula (1))) and 25.00 g of a polyfunctional alicyclic epoxy resin (EHPE3150 (structural formula (2))) are mixed, The mixture was kept at 110 ° C. and stirred well until EHPE3150 (solid) was dissolved. After dissolving EHPE3150, it is allowed to stand at room temperature, and when the temperature drops to near room temperature, Wandamine HM (manufactured by Shin Nippon Rika Co., Ltd., (Structural Formula (4))) 20.31 g and 1,3-BAC (Structural Formula ( 5)) A mixed hardener 27.08 g in which 6.77 g was mixed well and mixed in advance was mixed and stirred to obtain a resin composition used for a neutron shielding material.
As a result of measuring the hydrogen content in the resin composition, the hydrogen content was 9.8% by weight or more and satisfied the standard value. On the other hand, the resin composition for neutron shielding material was cured at 80 ° C. × 30 min + 150 ° C. × 2 hr, and the thermal weight loss was measured. As a result, the weight residual rate at 200 ° C. was 99.5% by weight or more and the weight residual rate 90% by weight. Showed a very good heat resistance and thermal stability of about 370 ° C.
[0039]
[Example 5]
44.94 g of a polyfunctional glycidylamine type epoxy resin (TETRAD-C (Structural Formula (1))) and 3.18 g of an alicyclic epoxy resin (Celoxide 2021P (Structural Formula (3))) as an epoxy resin and a polyfunctional alicyclic ring Type epoxy resin (EHPE3150 (structural formula (2))) 25.00 g was mixed and kept at 110 ° C. and stirred well until EHPE3150 (solid) was dissolved. After dissolving EHPE3150, it is allowed to stand at room temperature, and when the temperature drops to around room temperature, 20.16 g of Wandamine HM ((Structural Formula (4))) and 6.72 g of 1,3-BAC (Structural Formula (5)) are preliminarily used as curing agents. 26.88 g of mixed hardener mixed well and mixed was mixed and stirred to obtain a resin composition used for a neutron shielding material.
As a result of measuring the hydrogen content in the resin composition, the hydrogen content was about 9.8% by weight and satisfied the standard value. On the other hand, the resin composition for neutron shielding material was cured at 80 ° C. × 30 min + 150 ° C. × 2 hr, and the thermal weight loss was measured. As a result, the weight residual rate at 200 ° C. was 99.5% by weight or more and the weight residual rate 90% by weight. The temperature of 370 ° C. or higher showed extremely good heat resistance and thermal stability.
[0040]
[Example 6]
49.654 g of polyfunctional glycidylamine type epoxy resin (TETRAD-C (structural formula (1))) and 2.146 g of bisphenol A type epoxy resin (Epicoat 828 (structural formula (6))) as an epoxy resin and polyfunctional alicyclic ring Type epoxy resin (EHPE3150 (structural formula (2))) 22.2 g was mixed and kept at 110 ° C. and stirred well until EHPE3150 (solid) was dissolved. After dissolving EHPE3150, it is allowed to stand at room temperature. When the temperature drops to near room temperature, 15.6 g of Wandamine HM ((Structural Formula (4))) and 10.4 g of 1,3-BAC (Structural Formula (5)) are preliminarily used as curing agents. 26 g of mixed hardener mixed well and mixed was mixed and stirred to obtain a resin composition used for a neutron shielding material.
As a result of measuring the hydrogen content in the resin composition, the hydrogen content was about 9.8% by weight and satisfied the standard value. On the other hand, the resin composition for neutron shielding material was cured at 80 ° C. × 30 min + 150 ° C. × 2 hr, and the thermal weight loss was measured. As a result, the weight residual rate at 200 ° C. was 99.5% by weight or more and the weight residual rate 90% by weight. The temperature of 370 ° C. or higher showed extremely good heat resistance and thermal stability.
[0041]
[Example 7]
As epoxy resin, polyfunctional glycidylamine type epoxy resin (TETRAD-C (Structural Formula (1))) 50.55 g and alicyclic epoxy resin (Celoxide 2021P (Structural Formula (3))) 20.65 g as curing agent 21.6 g of Wandamine HM (Structural Formula (4)) and 7.2 g of 1,3-BAC (Structural Formula (5)) were mixed in advance and mixed with 28.8 g of a mixed curing agent mixed and stirred. It was set as the resin composition used for neutron shielding materials.
As a result of measuring the hydrogen content in the resin composition, the hydrogen content was 9.8% by weight or more and satisfied the standard value. On the other hand, the resin composition for neutron shielding material was cured at 80 ° C. × 30 min + 150 ° C. × 2 hr, and the thermal weight loss was measured. As a result, the weight residual rate at 200 ° C. was 99.5% by weight or more and the weight residual rate 90% by weight. Exhibited a good heat resistance and thermal stability of about 340 ° C.
[0042]
[Example 8]
As epoxy resin, polyfunctional glycidylamine type epoxy resin (TETRAD-C (structural formula (1))) 57.17 g and bisphenol A type epoxy resin (Epicoat 828 (structural formula (6))) 14.2 g Mix and stir 28.63 g of a mixed curing agent in which 21.47 g of Wandamine HM (Structural Formula (4)) and 7.16 g of 1,3-BAC (Structural Formula (5)) are mixed in advance and mixed. It was set as the resin composition used for neutron shielding materials.
As a result of measuring the hydrogen content in the resin composition, the hydrogen content was about 9.8% by weight and satisfied the standard value. On the other hand, the resin composition for neutron shielding material was cured at 80 ° C. × 30 min + 150 ° C. × 2 hr, and the thermal weight loss was measured. As a result, the weight residual rate at 200 ° C. was 99.5% by weight or more and the weight residual rate 90% by weight. Exhibited a good heat resistance and thermal stability of about 340 ° C.
[0043]
[Example 9]
As epoxy resin, polyfunctional glycidylamine type epoxy resin (TETRAD-C (structural formula (1))) 60.44 g and alicyclic epoxy resin (celloxide 2021P (structural formula (3))) 15.78 g as curing agent 23.78 g of 1,3-BAC (structural formula (5)) was mixed and stirred to obtain a resin composition used for a neutron shielding material.
As a result of measuring the hydrogen content in the resin composition, the hydrogen content was about 9.8% by weight and satisfied the standard value. On the other hand, the resin composition for neutron shielding material was cured at 80 ° C. × 30 min + 150 ° C. × 2 hr, and the thermal weight loss was measured. As a result, the weight residual rate at 200 ° C. was 99.5% by weight or more and the weight residual rate 90% by weight. The temperature was 330 ° C. or higher, indicating good heat resistance and thermal stability.
[0044]
[Example 10]
39.28 g of polyfunctional glycidylamine type epoxy resin (TETRAD-C (structural formula (1))) and hydrogenated bisphenol A type epoxy resin (manufactured by Yuka Shell Epoxy Co., Ltd.), YL6663 (structural formula (7)) )) 10.00 g and 25.00 g of a polyfunctional alicyclic epoxy resin (EHPE3150 (structural formula (2))) were mixed and kept at 110 ° C. until the EHPE3150 (solid) was dissolved. After dissolving EHPE3150, it is allowed to stand at room temperature. When the temperature drops to near room temperature, 19.29 g of Wandamine HM ((Structural Formula (4))) and 6.43 g of 1,3-BAC (Structural Formula (5)) are preliminarily used as curing agents. A resin composition used for a neutron shielding material was prepared by mixing and stirring 25.72 g of a mixed hardener mixed well and mixed.
As a result of measuring the hydrogen content in the resin composition, the hydrogen content was 9.8% by weight or more (about 9.9% by weight or more), which exceeded the standard value. On the other hand, the resin composition for neutron shielding material was cured at 80 ° C. × 30 min + 150 ° C. × 2 hr, and the thermal weight loss was measured. As a result, the weight residual rate at 200 ° C. was 99.5% by weight or more and the weight residual rate 90% by weight. Showed a very good heat resistance and thermal stability of about 370 ° C.
[0045]
[Example 11]
As the epoxy resin, 47.92 g of a polyfunctional glycidylamine type epoxy resin (TETRAD-C (structural formula (1))) and 25.00 g of a polyfunctional alicyclic epoxy resin (EHPE3150 (structural formula (2))) are mixed, The mixture was kept at 110 ° C. and stirred well until EHPE3150 (solid) was dissolved. After dissolving EHPE3150, it is allowed to stand at room temperature, and when the temperature drops to near room temperature, 20.1 g of Wandamine HM ((Structural Formula (4))) and 6.7 g of 1,3-BAC (Structural Formula (5)) and imidazole are used as curing agents. 27.07 g of a mixed hardener prepared by mixing 0.27 g of the compound (structural formula (8)) in advance and mixed together was mixed and stirred to obtain a resin composition used for a neutron shielding material.
As a result of measuring the hydrogen content in the resin composition, the hydrogen content was 9.8% by weight or more and satisfied the standard value. On the other hand, the resin composition for neutron shielding material was cured at 80 ° C. × 30 min + 150 ° C. × 2 hr, and the thermal weight loss was measured. As a result, the weight residual rate at 200 ° C. was 99.5% by weight or more and the weight residual rate 90% by weight. The temperature of 370 ° C. or higher showed extremely good heat resistance and thermal stability.
[0046]
[Example 12]
Here, the neutron shielding material which mixed the neutron absorber was evaluated. 49.654 g of polyfunctional glycidylamine type epoxy resin (TETRAD-C (structural formula (1))) and 2.146 g of bisphenol A type epoxy resin (Epicoat 828 (structural formula (6))) as an epoxy resin and polyfunctional alicyclic ring Type epoxy resin (EHPE3150 (structural formula (2))) 22.2 g was mixed and kept at 110 ° C. and stirred well until EHPE3150 (solid) was dissolved. After dissolving EHPE3150, it is allowed to stand at room temperature. When the temperature drops to near room temperature, 15.6 g of Wandamine HM ((Structural Formula (4))) and 10.4 g of 1,3-BAC (Structural Formula (5)) are preliminarily used as curing agents. 26 g of mixed hardener mixed well and mixed was mixed and stirred. To this, 146.5 g of magnesium hydroxide and 3.5 g of boron carbide were mixed and stirred to obtain a composition for a neutron shielding material. As a standard of the hydrogen content required for the neutron shielding material, the hydrogen content density is 0.096 g / cm. ^Three Although it is above, as a result of measuring the hydrogen-containing density of the prepared neutron shielding material composition, 0.096 g / cm ^Three The standard value was satisfied. On the other hand, the resin composition for neutron shielding material was cured at 80 ° C. × 30 min + 150 ° C. × 2 hr, and the thermal weight loss was measured. As a result, the weight residual rate at 200 ° C. was 99.5% by weight or more and the weight residual rate 90% by weight. The temperature of 370 ° C. or higher showed extremely good heat resistance and thermal stability.
[0047]
Next, as a comparative example, the performance of a neutron shielding material using a composition conventionally used was evaluated. As in the examples, no refractory material or neutron absorber was added. Similarly to the examples, the hydrogen content was determined by component analysis, and the thermogravimetric decrease was measured by TGA.
[0048]
[Comparative Example 1]
Neutron shielding by mixing and stirring bisphenol A type epoxy resin (Epicoat 828 (structural formula (6))) and polyamine-based curing agent at a ratio of 1: 1 (stoichiometrically equivalent) as an epoxy resin. The resin composition used for the material was used. Unlike those used in the composition of the present invention, the polyamine-based curing agent does not have a rigid structure with high heat resistance, and its blending amount is also large as a ratio.
As a result of measuring the hydrogen content in the resin composition by the same method as in Example 1, the hydrogen content was 9.8% by weight or more and satisfied the reference value. On the other hand, the resin composition for neutron shielding material was cured at 80 ° C. × 30 min + 150 ° C. × 2 hr, and the thermal weight loss was measured. As a result, the temperature at 200 ° C. was 99% by weight or less and the weight remaining rate was 90% by weight. The heat resistance and heat stability were inferior to those of the group of Examples. This composition system simulates a system similar to a conventional resin composition for neutron shielding materials, but Comparative Example 1 is suitable in terms of hydrogen content, but has heat resistance and thermal stability. Specifically, it is a low value compared with the group of Examples, and it can be seen that the neutron shielding materials produced in Examples 1 to 12 are excellent in heat resistance and thermal stability.
[0049]
[Comparative Example 2]
81.4 g of a bisphenol A type epoxy resin (Epicoat 828 (structural formula (6))) as an epoxy resin and 18.6 g of isophoronediamine as a curing agent were thoroughly stirred to obtain a resin composition used for a neutron shielding material.
As a result of measuring the hydrogen content in the resin composition, the hydrogen content was 8.2% by weight or less, far below the standard value and not yet achieved. On the other hand, the resin composition for neutron shielding material was cured at 80 ° C. × 30 min + 150 ° C. × 2 hr, and the thermal weight loss was measured. As a result, the residual weight ratio at 200 ° C. was about 99.5% by weight, and the residual weight ratio was 90% by weight. The temperature was about 350 ° C., and the heat resistance and thermal stability were good.
Although this composition system is good in heat resistance and thermal stability, it was unsuitable as a resin composition for a neutron shielding material in terms of hydrogen content as compared with a group of examples.
[0050]
[Comparative Example 3]
Mix and stir the polyfunctional glycidylamine type epoxy resin (TETRAD-C (structural formula (1))) and polyamine type curing agent as an epoxy resin at a ratio of 1: 1 (equal stoichiometric amount). Thus, a resin composition used for a neutron shielding material was obtained.
As a result of measuring the hydrogen content in the resin composition, the hydrogen content was 9.8% by weight or more (about 10% by weight or more), which exceeded the standard value. On the other hand, the resin composition for neutron shielding material was cured at 80 ° C. × 30 min + 150 ° C. × 2 hr, and the thermal weight loss was measured. As a result, the weight residual rate at 200 ° C. was 99.0% by weight or less, and the weight residual rate was 90% by weight. The temperature of 270 ° C. or lower was inferior in heat resistance and thermal stability as compared with a group of examples.
[0051]
[Comparative Example 4]
81.7g of epoxy resin (epoxy equivalent 190) having a structure in which OH at both ends of polypropylene glycol is substituted with glycidyl ether as an epoxy resin and 18.3g of isophoronediamine as a curing agent are thoroughly stirred for neutron shielding materials. It was set as the resin composition used for.
As a result of measuring the hydrogen content in the resin composition, the hydrogen content was 9.8% by weight or more and satisfied the standard value. On the other hand, the resin composition for neutron shielding material was cured at 80 ° C. × 30 min + 150 ° C. × 2 hr, and the thermal weight loss was measured. As a result, the weight residual rate at 200 ° C. was 99.5% by weight or less and the weight residual rate was 90% by weight. The temperature was less than about 250 ° C., and the heat resistance and thermal stability were extremely inferior to those of the group of examples.
[0052]
[Comparative Example 5]
78.5 g of 1,6-hexane diglycidyl ether (epoxy equivalent 155) as an epoxy resin and 21.5 g of isophorone diamine as a curing agent were well stirred to obtain a resin composition used for a neutron shielding material. The epoxy compound used in the composition of the present invention is an epoxy having a cyclic structure, whereas 1,6 hexanediglycidyl ether is an epoxy having an aliphatic chain structure having no cyclic structure.
As a result of measuring the hydrogen content in the resin composition, the hydrogen content was 9.8% by weight or more and satisfied the standard value. On the other hand, the resin composition for neutron shielding material was cured at 80 ° C. × 30 min + 150 ° C. × 2 hr, and the thermal weight loss was measured. As a result, the residual weight rate at 200 ° C. was 99.5% by weight or less, and the residual weight rate was 90% by weight. The temperature was less than 300 ° C. and was inferior in heat resistance and thermal stability as compared with a group of examples.
[0053]
[Comparative Example 6]
Here, evaluation was performed by adding a neutron absorber to a conventional resin component. As an epoxy resin, magnesium hydroxide is mixed with 50 g of bisphenol A type epoxy resin (Epicoat 828 (Structural Formula (6))) and 50 g of a polyamine curing agent (a stoichiometric equivalent ratio). 146.5 g and boron carbide 3.5 g were mixed and stirred to obtain a composition for a neutron shielding material.
As a standard of the hydrogen content required for the neutron shielding material, the hydrogen content density is 0.096 g / cm. ^Three Although it is above, as a result of measuring the hydrogen-containing density of the prepared neutron shielding material composition, 0.096 g / cm ^Three The standard value was satisfied. On the other hand, the resin composition for neutron shielding material was cured at 80 ° C. × 30 min + 150 ° C. × 2 hr, and the thermal weight loss was measured. As a result, the temperature at 200 ° C. was 99% by weight or less and the weight remaining rate was 90% by weight. The heat resistance and heat stability were inferior to those of the group of Examples. Further, after the cured product was sealed in a sealed container, a heat resistance durability test of 190 ° C. × 1000 hr was performed. The compressive strength decreased by 30% or more compared to before the test, and the durability under a high temperature environment was low.
This composition system simulates the same system as the composition for neutron shielding materials used conventionally. The composition of Comparative Example 6 is suitable in terms of hydrogen content, but the heat resistance and heat stability are lower than those of the composition of the present invention of Example 12, and the composition of the present invention. It can be seen that the product is excellent in heat resistance and heat stability.
[0054]
【The invention's effect】
The neutron shielding material of the present invention has good heat resistance and secures neutron shielding ability using an epoxy resin and a curing agent with improved heat resistance.

Claims

A compound having the following structural formula as an essential component;
(In Structural Formula (2), R ₀ is an alkyl group having 1 to 10 carbon atoms, or H, and n = 1 to 24);
(In the structural formula (3), n = 1~8) and,
(In Structural Formula (7), R _{5 to} R ₈ are each independently selected from the group consisting of CH ₃ , H, F, Cl, and Br, n = 0 to 2),
A composition for a neutron shielding material comprising one or more compounds selected from the group consisting of compounds having the structural formula: a curing agent component having at least one ring structure and a plurality of amino groups, and a boron compound. object.

The curing agent component is
The composition for neutron shielding materials according to claim 1, comprising a compound having the structural formula:

The curing agent component is
When,
(In the structural formula (8), R _{9 to} R ₁₁ are each independently, C is an alkyl group having 1 to 18 or H), or further includes both of them) Item 3. The composition for neutron shielding material according to Item 1 or 2.

The composition for neutron shielding materials according to any one of claims 1 to 3, further comprising a filler.

The composition for neutron shielding materials according to any one of claims 1 to 4, further comprising a refractory material.

The composition for neutron shielding materials according to claim 5, comprising at least one of magnesium hydroxide and aluminum hydroxide as the refractory material.

The neutron shielding material manufactured with the composition for neutron shielding materials in any one of Claims 1-6.

A neutron shielding container manufactured by the neutron shielding material according to claim 7.