JP3615875B2 - Methacrylic resin casting polymer - Google Patents
Methacrylic resin casting polymer Download PDFInfo
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- JP3615875B2 JP3615875B2 JP22186496A JP22186496A JP3615875B2 JP 3615875 B2 JP3615875 B2 JP 3615875B2 JP 22186496 A JP22186496 A JP 22186496A JP 22186496 A JP22186496 A JP 22186496A JP 3615875 B2 JP3615875 B2 JP 3615875B2
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Description
【0001】
【発明の属する技術分野】
本発明は、メタクリル酸メチルを主体とする単量体あるいはこれとその部分重合体との混合物を鋳型重合して得られる耐溶剤性に優れたメタクリル樹脂注型重合品に関する。
【0002】
【従来の技術】
メタクリル樹脂板の製造法には鋳型製板方式や押出製板方式等があるが、樹脂を溶融成形した押出板に比べ、メタクリル酸メチルを主体とする単量体を鋳型重合させて得られるメタクリル樹脂注型品は光学歪も少ない上、分子量の選択範囲が広いので、耐薬品性、加工性、機械的強度等を高めることが出来ることから、多くの分野で使用されている。
しかしながら、メタクリル樹脂板はごくまれに、溶剤接着などの際に、樹脂板に溶剤が接触すると表面が白化することが問題点とされており、この点の改善が望まれていた。
【0003】
【発明が解決しようとする課題】
本発明の目的は、メタクリル樹脂注型品が溶剤と接触した際に、注型品表面が白化することのない耐溶剤性に優れたメタクリル樹脂注型品を提供することにある。
【0004】
【課題を解決するための手段】
本発明者等は上記目的を解決するべく鋭意検討を進めた結果、メタクリル酸メチル単量体あるいはこれとその重合体との混合物にサリチル酸およびサリチル酸ナトリウムを添加することにより、メタクリル系樹脂の特徴である優れた透明性を維持したまま、耐溶剤性に優れたメタクリル樹脂注型重合品が得られることを見出し、本発明に至った。
【0005】
すなわち本発明は、メタクリル酸メチル60〜100重量%と他の共重合可能なビニル系モノマー40〜0重量%からなる樹脂成分100重量部と、サリチル酸0.001〜0.03重量部およびサリチル酸ナトリウム0.001〜0.03重量部とから製造されるメタクリル樹脂注型重合品にある。
【0006】
さらに本発明は、メタクリル酸メチル60〜100重量%と他の共重合可能なビニル系モノマー40〜0重量%からなる樹脂成分100重量部と、サリチル酸0.001〜0.03重量部、サリチル酸ナトリウム0.001〜0.03重量部およびトリフェニルフォスフィン0.01〜0.1重量部とから製造されることを特徴とするメタクリル樹脂注型重合品にある。
【0007】
【発明の実施形態】
本発明において樹脂成分を構成する単量体は、メタクリル酸メチル単量体単独のほか、メタクリル酸メチルと共重合可能な他のビニル系モノマーとの単量体混合物である。
【0008】
メタクリル酸メチルと共重合されるビニル系モノマーは、例えばメタクリル酸エチル、メタクリル酸イソプロピル、メタクリル酸t−ブチル、メタクリル酸s−ブチル、メタクリル酸n−ブチル、メタクリル酸アミル、メタクリル酸オクチル、メタクリル酸2−エチルヘキシル、メタクリル酸ラウリル、メタクリル酸フェニル、メタクリル酸シクロヘキシル、メタクリル酸ベンジル等のシクロアルキル基、ベンジル基を含むアルキル基の炭素数1〜12のメタクリル酸エステル類;メタクリル酸ボルニル、メタクリル酸イソボルニル、メタクリル酸フェンチル、メタクリル酸1−メチンチル、メタクリル酸アダンチル、メタクリル酸ジメチルアダマンテルなどの炭素数8〜20のアルキル基または脂環式炭化水素基を有するメタクリル酸エステル類;アクリル酸メチル、アクリル酸エチル、アクリル酸イソプロピル、アクリル酸ブチル、アクリル酸t−ブチル、アクリル酸アミル、アクリル酸オクチル、アクリル酸2−エチルヘキシル、アクリル酸ラウリル、アクリル酸シクロヘキシル、アクリル酸フェニル、アクリル酸ベンジル等のアクリル酸エステル類;スチレン、α−メチルスチレン、パラメチルスチレン、イソプロペニルスチレン、ビニルトルエン等のビニル芳香族類;アクリロニトリル、メタクリロニトリル等の不飽和ニトリル類;メタクリル酸、アクリル酸、無水マレイン酸等の不飽和カルボン酸類;エチレングリコールジ(メタ)アクリレート、ジエチレングリコールジ(メタ)アクリレート、ジビニルベンゼン等の多不飽和化合物等が挙げられる。しかし、これらに限定されるものではなく、また、これらは1種でまたは2種以上を併用して用いることができる。
【0009】
本発明のメタクリル樹脂注型重合品を構成する樹脂成分に使用される単量体の組成割合は、通常メタクリル酸メチル60〜100重量%と他の共重合可能なビニル系モノマー40〜0重量%の範囲であるが、改良目的によっては他の共重合可能なビニル系モノマーの使用量を、重合して得られるメタクリル樹脂本来の物性を損なわない程度の使用量として5重量%以下にすることが望ましい。
【0010】
本発明においては上記の単量体または単量体混合物(以下、これらを単に「単量体」と称する。)が鋳型重合に供せられるが、前記単量体の代わりに単量体とその重合体の混合物(以下、「シラップ」と称する。)を重合に供しても何等差支えない。
【0011】
本発明のメタクリル樹脂は、上記の樹脂構成成分にサリチル酸及びサリチル酸ナトリウムを含有していることに特徴がある。これらの中サリチル酸ナトリウムは樹脂注型重合品の表面の耐溶剤性を高める。しかしサリチル酸ナトリウムの添加で樹脂注型品表面の耐溶剤性は得られるものの、透明性が失われ熱水浸漬時に吸水白化が生じることから、サリチル酸を相溶化剤として用いる。
【0012】
サリチル酸ナトリウムの使用量は、単量体もしくはシラップ100重量部に対して0.001〜0.03重量部の範囲で用いるのが好ましい。使用量が0.001重量部未満では樹脂注型品表面の耐溶剤性が十分でなく、また、使用量が0.03重量部を超えると得られる樹脂注型品の透明性が低下し、熱水に浸漬した際の吸水白化が激しくなる。樹脂構成成分へのサリチル酸ナトリウムの添加は、添加量の等倍から20倍の水を溶媒として用いる。
【0013】
サリチル酸の使用量は、単量体もしくはシラップ100重量部に対して0.001〜0.03重量部の範囲で用いるのが好ましい。使用量が0.001重量部未満では得られる樹脂注型品の透明性が低下し、熱水に浸漬した際に樹脂注型品の吸水白化が生じる。また、使用量が0.03重量部を超えると得られる樹脂注型品の強度低下をもたらすようになる。
【0014】
本発明において、重合開始剤に有機過酸化物系のものを使用する場合、樹脂注型品表面の耐溶剤性を更に高めるトリフェニルフォスフィン(以下、TPPと略記する。)を併用することが好ましい。TPPの使用量は、単量体もしくはシラップ100重量部に対して0.01〜0.1重量部の範囲で用いるのが好ましく、その使用量が0.01重量部未満では樹脂注型品表面の耐溶剤性が十分でなく、また、使用量が0.1重量部を超えると得られる樹脂注型品が着色したり強度低下をもたらすようになる。
【0015】
本発明のメタクリル樹脂注型重合品は鋳型重合法によって重合される。
【0016】
鋳型重合に当り単量体もしくはシラップの重合に用いることのできる重合開始剤としては、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)等のアゾ系重合開始剤、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、t−ヘキシルパーオキシピバレート等の有機過酸化物等が挙げられる。
【0017】
また、重合に当り、必要に応じて分子量調節剤を用いる。これには、n−ブチルメルカプタン、n−ドデシルメルカプタン、オクチルメルカプタン等のアルキルメルカプタン等が挙げられる。
【0018】
重合温度は、使用する重合開始剤の種類により異なるが、一般に40〜170℃であり、第1段目を40〜90℃、第2段目を100〜140℃とする2段階の重合温度で重合するのが好ましい。
【0019】
重合に当っては、通常のメタクリル樹脂あるいはその変性品を製造する際に用いられる種々の添加剤を加えることができる。添加剤としては、着色に用いられる染料、顔料あるいは酸化防止剤、紫外線吸収剤等の安定剤あるいは難燃剤、可塑剤あるいは樹脂注型品の鋳型よりの剥離を容易にする剥離剤、連鎖移動剤、架橋剤等である。
【0020】
【実施例】
以下、実施例により本発明を詳しく説明する。説明中「部」は重量部を意味する。なお、実施例における物性評価は下記の方法に基づいて行った。
(1)透明性
暗所の照明下で樹脂注型品の透明性および着色を観察し、良好なものを○、やや良好なものを△、不良なものを×と評価した。
(2)耐熱水性
80℃の温水中に樹脂注型品を24時間浸漬後、白化の度合いで白化なし:○、わずかに白化:△、白化:×と評価した。
(3)耐溶剤性
樹脂注型品を塩化メチレン蒸気に暴露した際の樹脂注型品表面の白化の度合いで白化なし:○、わずかに白化:△、白化:×と評価した。
【0021】
[実施例1〜3]
冷却管、温度計及び撹拌機を備えた反応機に、メタクリル酸メチルを供給し、撹拌しながら加熱して内温が80℃になった時点で2,2′−アゾビス−(2,4−ジメチルバレロニトリル)0.05部を添加し、更に内温が90℃になるまで加熱しその温度を8分間保持した後、室温まで冷却して重合率約22%、20℃における粘度1500センチポイズのシラップを得た。
【0022】
次いで、このシラップ100部に、重合開始剤として2,2′−アゾビス−(2,4−ジメチルバレロニトリル)を0.083部、表1に示す量のサリチル酸と、純水1000ppmを溶媒としたサリチル酸ナトリウムを添加した後、撹拌し、ポリ塩化ビニル製ガスケットを介してなる3mmの間隔で相対する2枚のSUS304板で形成した鋳型に注入し、78℃の温水中に30分間浸漬し重合硬化させた後、135℃の空気加熱炉中で60分間熱処理した。冷却後鋳型を脱枠し板厚約3mmの樹脂注型品を得た。この樹脂注型品の物性を評価した。結果を表1に示した。
【0023】
[比較例1〜5]
実施例1〜3で用いられたものと同様のシラップ100部に、重合開始剤として2,2′−アゾビス−(2,4−ジメチルバレロニトリル)を0.083部、表1に示す量のサリチル酸と、純水0.1部を溶媒としたサリチル酸ナトリウムを添加し、以下実施例1と同様に操作して樹脂注型品を得、物性を評価した。結果を併せて表1に示した。
【0024】
表1より明らかな如く本発明の樹脂注型品である実施例1〜3は透明性を保ちつつ、熱水浸漬後の白化および溶剤蒸気暴露後の注型品表面の白化を抑えているのに対し、サリチル酸とサリチル酸ナトリウムを添加しない樹脂注型品(比較例1)は溶剤蒸気暴露後に注型品表面が白化している。また、好ましい使用量の範囲から外れた樹脂注型品(比較例2、3)は溶剤蒸気暴露後に注型品表面が白化したり、透明性が失われている。サリチル酸ナトリウムを単独で添加した樹脂注型品(比較例4)は透明性が失われ、サリチル酸を単独で添加した樹脂注型品(比較例5)は溶剤蒸気暴露後に注型品表面が白化している。
【0025】
[実施例4〜6]
実施例1と同様の装置に、メタクリル酸メチル95.7重量部、アクリル酸ブチル4.3重量部を供給し、分子量調節剤としてn−ドデシルメルカプタンを0.063部添加した後、撹拌しながら加熱し内温が80℃になった時点で2,2′−アゾビス−(2,4−ジメチルバレロニトリル)0.05部を添加し、更に内温が90℃になるまで加熱し、その温度を13分保持した後、室温まで冷却して重合率約26%、20℃における粘度2000センチポイズのシラップを得た。
【0026】
次いで、このシラップ100部に、分子量調節剤としてn−ドデシルメルカプタンを0.03部、有機過酸化物系の重合開始剤としてt−ヘキシルパーオキシピバレートを0.32部、表1に示す量のTPP、サリチル酸および純水0.1部を溶媒としたサリチル酸ナトリウムを添加し、以下、実施例1と同様に操作して樹脂注型品を得、物性を評価した。その結果を表1に示した。
【0027】
[比較例6〜7]
実施例4で得られたものと同様のシラップ100部に、分子量調節剤としてn−ドデシルメルカプタンを0.03部、有機過酸化物系の重合開始剤としてt−ヘキシルパーオキシピバレートを0.32部、表1に示す量のTPP、サリチル酸ナトリウムおよび純水0.1部を溶媒としたサリチル酸ナトリウムを添加し、以下、実施例4と同様に操作して、樹脂注型品を得、物性を評価した。その結果を併せて、表1に示した。
【0028】
表1より明らかな如く、本発明の樹脂注型品である実施例4〜6は透明性を保ちつつ、熱水浸漬後の白化および溶剤蒸気暴露後の注型品表面の白化を抑えているのに対し、好ましい使用量の範囲から外れた樹脂注型品(比較例6、7)は溶剤蒸気暴露後に注型品表面が白化したり、透明品が失われている。
【0029】
[実施例7〜8]
実施例1と同様の装置に、メタクリル酸メチルを供給し、撹拌しながら加熱し内温が75℃になった時点でアゾビスイソブチロニトリル0.002部を添加し、更に内温95℃まで加熱し10分間保持した後、室温まで冷却して重合率約8%20℃における粘度200センチポイズのシラップを得た。
【0030】
次いで、このシラップ100部に、重合開始剤として2,2′−アゾビス−(2,4−ジメチルバレロニトリル)を0.003部、表1に示す量のサリチル酸および純水0.1部を溶媒としたサリチル酸ナトリウムを添加した後、撹拌し、ポリ塩化ビニル製ガスケットを介してなる10mmの間隔で相対する2枚の無機ガラス板で形成した鋳型に注入し、65℃の温水中に6時間浸漬し重合硬化させた後、125℃の空気加熱炉中で3時間熱処理した。冷却後鋳型を脱枠し板厚約10mmの樹脂注型品を得た。この樹脂注型品の物性を評価し表1に示した。
【0031】
[比較例8〜9]
実施例7で得られたものと同様のシラップ100部に、表1に示す量のサリチル酸および純水0.1部を溶媒としたサリチル酸ナトリウムを添加し、以下実施7と同様、樹脂注型品を得、物性を評価した。その結果を表1に示した。
【0032】
表1より明らかな如く、本発明の樹脂注型品である実施例7,8は透明性を保ちつつ、熱水浸漬後の白化および溶剤蒸気暴露後の注型品表面の白化を抑えているのに対し、好ましい使用量の範囲から外れた樹脂注型品(比較例8,9)は溶剤蒸気暴露後に注型品表面が白化したり、透明性が失われている。
【0033】
【表1】
【0034】
【発明の効果】
本発明のメタクリル樹脂注型重合品は、メタクリル樹脂の特徴である優れた透明性を維持したまま、樹脂を溶剤蒸気に暴露した際に発生する樹脂表面の白化を防止することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a methacrylic resin cast polymer product excellent in solvent resistance obtained by template polymerization of a monomer mainly composed of methyl methacrylate or a mixture thereof with a partial polymer thereof.
[0002]
[Prior art]
There are methods for producing methacrylic resin plates, such as a mold plate method and an extrusion plate method, but methacrylic resin obtained by template polymerization of a monomer mainly composed of methyl methacrylate, compared to an extruded plate obtained by melt molding a resin. Resin cast products are used in many fields because they have low optical distortion and a wide range of molecular weights, which can improve chemical resistance, processability, mechanical strength, and the like.
However, methacrylic resin plates are very rarely whitened when a solvent comes into contact with the resin plate during solvent bonding, and it has been desired to improve this point.
[0003]
[Problems to be solved by the invention]
An object of the present invention is to provide a methacrylic resin cast product having excellent solvent resistance that does not whiten the surface of the cast product when the methacrylic resin cast product comes into contact with a solvent.
[0004]
[Means for Solving the Problems]
As a result of diligent investigations to solve the above-mentioned object, the present inventors have added the characteristics of methacrylic resin by adding salicylic acid and sodium salicylate to a methyl methacrylate monomer or a mixture thereof and a polymer thereof. The inventors found that a methacrylic resin cast polymer product excellent in solvent resistance can be obtained while maintaining certain excellent transparency, and reached the present invention.
[0005]
That is, the present invention relates to 100 parts by weight of a resin component comprising 60 to 100% by weight of methyl methacrylate and 40 to 0% by weight of other copolymerizable vinyl monomers, 0.001 to 0.03 parts by weight of salicylic acid and sodium salicylate. It is in the methacrylic resin casting polymer manufactured from 0.001-0.03 weight part.
[0006]
Further, the present invention relates to 100 parts by weight of a resin component comprising 60 to 100% by weight of methyl methacrylate and 40 to 0% by weight of other copolymerizable vinyl monomers, 0.001 to 0.03 parts by weight of salicylic acid, and sodium salicylate. A methacrylic resin cast polymerized product produced from 0.001 to 0.03 part by weight and 0.01 to 0.1 part by weight of triphenylphosphine.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the monomer constituting the resin component is a monomer mixture of a methyl methacrylate monomer alone and other vinyl monomers copolymerizable with methyl methacrylate.
[0008]
Vinyl monomers copolymerized with methyl methacrylate are, for example, ethyl methacrylate, isopropyl methacrylate, t-butyl methacrylate, s-butyl methacrylate, n-butyl methacrylate, amyl methacrylate, octyl methacrylate, methacrylic acid. 2-ethylhexyl, lauryl methacrylate, phenyl methacrylate, cyclohexyl methacrylate, cycloalkyl groups such as benzyl methacrylate, methacrylic esters having 1 to 12 carbon atoms of alkyl group including benzyl group; bornyl methacrylate, isobornyl methacrylate Methacrylic acid ester having an alkyl group having 8 to 20 carbon atoms or an alicyclic hydrocarbon group such as phentyl methacrylate, 1-methynyl methacrylate, adanthyl methacrylate, dimethyl adamantel methacrylate, etc. Methyl acrylate, ethyl acrylate, isopropyl acrylate, butyl acrylate, t-butyl acrylate, amyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, cyclohexyl acrylate, phenyl acrylate Acrylic esters such as benzyl acrylate; vinyl aromatics such as styrene, α-methyl styrene, paramethyl styrene, isopropenyl styrene and vinyl toluene; unsaturated nitriles such as acrylonitrile and methacrylonitrile; methacrylic acid, Examples thereof include unsaturated carboxylic acids such as acrylic acid and maleic anhydride; polyunsaturated compounds such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate and divinylbenzene. However, it is not limited to these, Moreover, these can be used individually by 1 type or in combination of 2 or more types.
[0009]
The composition ratio of the monomer used in the resin component constituting the methacrylic resin cast polymer of the present invention is usually 60 to 100% by weight of methyl methacrylate and 40 to 0% by weight of other copolymerizable vinyl monomers. However, depending on the purpose of improvement, the amount of other copolymerizable vinyl monomers used may be 5% by weight or less as the amount used so as not to impair the original physical properties of the methacrylic resin obtained by polymerization. desirable.
[0010]
In the present invention, the above-mentioned monomer or monomer mixture (hereinafter simply referred to as “monomer”) is subjected to template polymerization. There is no problem even if a mixture of polymers (hereinafter referred to as “syrup”) is subjected to polymerization.
[0011]
The methacrylic resin of the present invention is characterized in that salicylic acid and sodium salicylate are contained in the above resin constituent components. Of these, sodium salicylate increases the solvent resistance of the surface of the resin cast polymer. However, the addition of sodium salicylate provides solvent resistance on the surface of the resin cast product, but it loses transparency and whitening occurs when immersed in hot water, so salicylic acid is used as a compatibilizing agent.
[0012]
The amount of sodium salicylate used is preferably in the range of 0.001 to 0.03 parts by weight with respect to 100 parts by weight of the monomer or syrup. If the amount used is less than 0.001 parts by weight, the solvent resistance of the surface of the resin cast product is not sufficient, and if the amount used exceeds 0.03 parts by weight, the transparency of the resin cast product obtained decreases, Water absorption whitening when immersed in hot water becomes severe. Addition of sodium salicylate to the resin component uses water as a solvent that is equal to or 20 times the amount added.
[0013]
The amount of salicylic acid used is preferably in the range of 0.001 to 0.03 parts by weight with respect to 100 parts by weight of the monomer or syrup. When the amount used is less than 0.001 part by weight, the transparency of the resulting resin cast product is lowered, and water absorption whitening of the resin cast product occurs when immersed in hot water. Moreover, when the usage-amount exceeds 0.03 weight part, the strength reduction of the resin cast product obtained will be brought about.
[0014]
In the present invention, when an organic peroxide type initiator is used as the polymerization initiator, triphenylphosphine (hereinafter abbreviated as TPP) for further improving the solvent resistance of the surface of the resin cast product may be used in combination. preferable. The amount of TPP used is preferably in the range of 0.01 to 0.1 parts by weight with respect to 100 parts by weight of monomer or syrup. If the amount used is less than 0.01 parts by weight, the surface of the resin cast product The solvent resistance of the resin is not sufficient, and when the amount used exceeds 0.1 parts by weight, the resulting resin cast product is colored or causes a decrease in strength.
[0015]
The methacrylic resin cast polymer of the present invention is polymerized by a template polymerization method.
[0016]
Examples of polymerization initiators that can be used for the polymerization of monomers or syrups in template polymerization include azo-based polymerizations such as azobisisobutyronitrile and 2,2'-azobis- (2,4-dimethylvaleronitrile). Examples thereof include organic peroxides such as an initiator, benzoyl peroxide, t-butylperoxy 2-ethylhexanoate, and t-hexylperoxypivalate.
[0017]
In the polymerization, a molecular weight regulator is used as necessary. This includes alkyl mercaptans such as n-butyl mercaptan, n-dodecyl mercaptan and octyl mercaptan.
[0018]
The polymerization temperature varies depending on the type of polymerization initiator used, but is generally 40 to 170 ° C, and is a two-stage polymerization temperature in which the first stage is 40 to 90 ° C and the second stage is 100 to 140 ° C. Polymerization is preferred.
[0019]
In the polymerization, various additives used in the production of ordinary methacrylic resins or modified products thereof can be added. Additives include dyes, pigments or antioxidants used for coloring, stabilizers such as ultraviolet absorbers or flame retardants, release agents that facilitate the release of molds from plasticizers or resin castings, chain transfer agents , A crosslinking agent, etc.
[0020]
【Example】
Hereinafter, the present invention will be described in detail by examples. In the description, “parts” means parts by weight. In addition, the physical property evaluation in an Example was performed based on the following method.
(1) Transparency The transparency and coloring of the resin cast product were observed under illumination in a dark place, and a good one was evaluated as ◯, a slightly good one as Δ, and a poor one as X.
(2) The resin cast product was immersed in warm water at 80 ° C. for 24 hours and then evaluated as whitening: No, whitening: Δ, whitening: x, depending on the degree of whitening.
(3) The degree of whitening of the surface of the resin cast product when the solvent-resistant resin cast product was exposed to methylene chloride vapor was evaluated as no whitening: ○, slightly whitened: Δ, and whitened: ×.
[0021]
[Examples 1 to 3]
Methyl methacrylate is supplied to a reactor equipped with a condenser, a thermometer and a stirrer, and heated with stirring, and when the internal temperature reaches 80 ° C., 2,2′-azobis- (2,4- 0.05 parts of dimethylvaleronitrile) was added, and the internal temperature was further increased to 90 ° C. and maintained at that temperature for 8 minutes. After cooling to room temperature, the polymerization rate was about 22% and the viscosity at 20 ° C. was 1500 centipoise. I got syrup.
[0022]
Next, 0.083 part of 2,2'-azobis- (2,4-dimethylvaleronitrile) as a polymerization initiator was used as a polymerization initiator in 100 parts of this syrup, and the amount of salicylic acid shown in Table 1 and pure water of 1000 ppm were used as solvents. After the addition of sodium salicylate, the mixture is stirred and poured into a mold made of two SUS304 plates facing each other at a distance of 3 mm through a polyvinyl chloride gasket, and immersed in warm water at 78 ° C. for 30 minutes for polymerization curing. Then, heat treatment was performed in an air heating furnace at 135 ° C. for 60 minutes. After cooling, the mold was removed to obtain a resin cast product having a plate thickness of about 3 mm. The physical properties of this resin casting were evaluated. The results are shown in Table 1.
[0023]
[Comparative Examples 1-5]
100 parts of syrup similar to those used in Examples 1 to 3, 0.083 parts of 2,2′-azobis- (2,4-dimethylvaleronitrile) as a polymerization initiator, in an amount shown in Table 1. Salicylic acid and sodium salicylate using 0.1 part of pure water as a solvent were added, and a resin cast product was obtained in the same manner as in Example 1 to evaluate physical properties. The results are also shown in Table 1.
[0024]
As apparent from Table 1, Examples 1 to 3 which are the resin cast products of the present invention keep the transparency and suppress whitening after immersion in hot water and whitening of the surface of the cast product after exposure to solvent vapor. On the other hand, in the resin cast product to which salicylic acid and sodium salicylate are not added (Comparative Example 1), the surface of the cast product is whitened after exposure to solvent vapor. In addition, the resin cast products (Comparative Examples 2 and 3) that are out of the range of the preferred use amount have a cast product surface whitened or lost transparency after exposure to solvent vapor. Transparency is lost in the resin cast product added with sodium salicylate alone (Comparative Example 4), and the cast product surface of the resin cast product added with salicylic acid alone (Comparative Example 5) is whitened after exposure to solvent vapor. ing.
[0025]
[Examples 4 to 6]
While supplying 95.7 parts by weight of methyl methacrylate and 4.3 parts by weight of butyl acrylate to the same apparatus as in Example 1, 0.063 part of n-dodecyl mercaptan was added as a molecular weight regulator, and then stirred. When the internal temperature reaches 80 ° C by heating, 0.05 part of 2,2'-azobis- (2,4-dimethylvaleronitrile) is added and further heated until the internal temperature reaches 90 ° C. Was kept for 13 minutes, and then cooled to room temperature to obtain a syrup having a polymerization rate of about 26% and a viscosity at 20 ° C. of 2000 centipoise.
[0026]
Next, in 100 parts of this syrup, 0.03 part of n-dodecyl mercaptan as a molecular weight regulator and 0.32 part of t-hexylperoxypivalate as an organic peroxide polymerization initiator are shown in Table 1. Sodium salicylate using 0.1 parts of TPP, salicylic acid and 0.1 part of pure water as a solvent was added, and the same procedure as in Example 1 was followed to obtain a resin cast product, and the physical properties were evaluated. The results are shown in Table 1.
[0027]
[Comparative Examples 6-7]
100 parts of syrup similar to that obtained in Example 4, 0.03 part of n-dodecyl mercaptan as a molecular weight regulator, and 0.03 part of t-hexylperoxypivalate as an organic peroxide polymerization initiator. 32 parts, sodium salicylate using TPP in the amounts shown in Table 1, sodium salicylate and 0.1 part of pure water as a solvent was added, and the same procedure as in Example 4 was followed to obtain a resin cast product. Evaluated. The results are also shown in Table 1.
[0028]
As is apparent from Table 1, Examples 4 to 6, which are resin cast products of the present invention, maintain whiteness and suppress whitening after immersion in hot water and whitening of the cast product surface after exposure to solvent vapor. On the other hand, in the resin cast products (Comparative Examples 6 and 7) that are out of the preferable range of use amount, the surface of the cast product is whitened or the transparent product is lost after the solvent vapor exposure.
[0029]
[Examples 7 to 8]
In the same apparatus as in Example 1, methyl methacrylate was supplied, heated with stirring, and when the internal temperature reached 75 ° C, 0.002 part of azobisisobutyronitrile was added, and the internal temperature was 95 ° C. Was heated to 10 minutes and then cooled to room temperature to obtain a syrup having a polymerization rate of about 8% and a viscosity of 200 centipoise at 20 ° C.
[0030]
Next, 0.003 part of 2,2'-azobis- (2,4-dimethylvaleronitrile) as a polymerization initiator and 0.1 part of salicylic acid and pure water in the amounts shown in Table 1 were added to 100 parts of this syrup as a solvent. After adding sodium salicylate as described above, the mixture was stirred and poured into a mold made of two inorganic glass plates facing each other at 10 mm intervals through a polyvinyl chloride gasket and immersed in warm water at 65 ° C. for 6 hours. After polymerization and curing, heat treatment was performed in an air heating furnace at 125 ° C. for 3 hours. After cooling, the mold was removed to obtain a resin cast product having a plate thickness of about 10 mm. The physical properties of this resin casting were evaluated and are shown in Table 1.
[0031]
[Comparative Examples 8-9]
To 100 parts of syrup similar to that obtained in Example 7, sodium salicylate with the amount of salicylic acid shown in Table 1 and 0.1 part of pure water as a solvent was added. And physical properties were evaluated. The results are shown in Table 1.
[0032]
As is apparent from Table 1, Examples 7 and 8 which are resin cast products of the present invention suppress the whitening after immersion in hot water and the surface of the cast product after exposure to solvent vapor while maintaining transparency. On the other hand, in the resin cast products (Comparative Examples 8 and 9) that are out of the range of the preferable use amount, the cast product surface is whitened or the transparency is lost after the solvent vapor exposure.
[0033]
[Table 1]
[0034]
【The invention's effect】
The methacrylic resin cast polymerized product of the present invention can prevent whitening of the resin surface that occurs when the resin is exposed to solvent vapor while maintaining the excellent transparency characteristic of the methacrylic resin.
Claims (2)
Priority Applications (1)
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JP22186496A JP3615875B2 (en) | 1996-08-06 | 1996-08-06 | Methacrylic resin casting polymer |
Applications Claiming Priority (1)
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JP22186496A JP3615875B2 (en) | 1996-08-06 | 1996-08-06 | Methacrylic resin casting polymer |
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JPH1045809A JPH1045809A (en) | 1998-02-17 |
JP3615875B2 true JP3615875B2 (en) | 2005-02-02 |
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JP22186496A Expired - Fee Related JP3615875B2 (en) | 1996-08-06 | 1996-08-06 | Methacrylic resin casting polymer |
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