JP2004083619A - Water-soluble polymer powder and method for producing the same - Google Patents
Water-soluble polymer powder and method for producing the same Download PDFInfo
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Abstract
Description
【0001】
【発明の属する技術分野】
この発明は、感温性遮光体、温度センサー、湿度センサー、感温性水性ゲル、化粧料添加物、医薬徐放性担体、皮膚貼付剤添加物などに使用される感温性を有する水溶性高分子粉末、より詳しくは、N−イソプロピルアクリルアミド系重合体粉末およびその製造法に関するものである。
【0002】
【従来の技術】
N−イソプロピルアクリルアミド又はN−イソプロピルメタクリルアミドを主構成単量体とするN−イソプロピルアクリルアミド系重合体、例えば、N−イソプロピルアクリルアミド重合体は、おおよそ32℃に転移温度をもち、転移温度以下では水溶性を示すが、高温領域では析出するという特殊な可逆的な性質を有するもので、感温性材料として注目されている。
【0003】
このN−イソプロピルアクリルアミド又はN−イソプロピルメタクリルアミドを主構成単量体とする重合体の製造方法としては、水溶液重合のほか逆相懸濁重合や析出重合などの方法が知られている。
【0004】
例えば、特開2000−230008号公報には、アゾ系開始剤による水溶液重合方法が記載され、また、特公平04−68321号公報には、ベンゼン溶媒による析出重合が、さらに、特公平05−48765号公報には、酢酸アルキル溶媒による析出重合が、さらにまた、特開昭60−120710号公報には、逆相懸濁重合がそれぞれ開示されている。
【0005】
【発明が解決しようとする課題】
しかしながら、前記逆相懸濁重合や析出重合によって得られたN−イソプロピルアクリルアミド系重合体には、重合に使用した溶剤が含まれており、粉末とした後でも、残存溶剤が完全には抜けきらないという欠点を有するもので、この残存溶剤は、特定の用途においては、残存単量体の含有量が大きな問題となっている。
【0006】
また、水溶液重合による方法では、残存溶剤の問題はないものの、一般的に残存単量体が多いといった傾向が見られ、感温性水性ゲル、化粧料添加物、医薬徐放性担体、皮膚貼付剤添加物などに使用される場合は、残存単量体の少ないことが一つの大きな要件とされているので、水溶液重合による重合体中の残存単量体を減少することが求められている。
【0007】
そこで、特開平08−59709公報には、水溶性開始剤を使用してN−置換アクリルアミド系単量体を、イソプロピルアセテート中で重合した後に溶剤を除去し、残存単量体の少ない重合体物を得る方法が開示されているが、残存単量体の量は、数100〜数1000のオーダーで、まだ不十分な状況である。
【0008】
この発明はかかる現状に鑑み、残存単量体の少ないN−イソプロピルアクリルアミドやN−イソプロピルメタクリルアミドを主単量体とする感温性水溶性高分子として、N−イソプロピルアクリルアミド系重合体粉末を提供すべく検討を行った。
【0009】
その結果、N−イソプロピルアクリルアミド系単量体を、特定の条件下で水溶液重合し、得られた重合体を温水で析出することによって、残存単量体の少ない感温性水溶性高分子粉末が得られることを見出し、この発明を完成した。
【0010】
【課題を解決するための手段】
すなわち、この発明の請求項1に記載の発明は、
N−イソプロピルアクリルアミド系単量体を、水溶性レドックス開始剤を用いて水溶液重合し、生成した重合体を40℃以上の温水で析出させること
を特徴とする水溶性高分子粉末の製造法である。
【0011】
また、この発明の請求項2に記載の発明は、
請求項1に記載の水溶性高分子粉末の製造法において、
前記N−イソプロピルアクリルアミド系単量体は、
N−イソプロピルアクリルアミド又はN−イソプロピルメタアクリルアミドであること
を特徴とするものである。
【0012】
また、この発明の請求項3に記載の発明は、
請求項1に記載の水溶性高分子粉末の製造法において、
前記N−イソプロピルアクリルアミド系単量体は、
N−イソプロピルアクリルアミド又はN−イソプロピルメタアクリルアミドを主体とし、ビニル重合性単量体を含有するものであること
を特徴とするものである。
【0013】
また、この発明の請求項4に記載の発明は、
請求項2に記載の水溶性高分子粉末の製造法において、
前記水溶液重合は、
N−イソプロピルアクリルアミドの水溶液中の濃度を、18質量%以下、重合開始温度を10℃以下、重合ピーク温度を40℃以下の条件下に行うこと
を特徴とするものである。
【0014】
また、この発明の請求項5に記載の発明は、
請求項1に記載の水溶性高分子粉末の製造法において、
前記水溶性レドックス開始剤は、
過硫酸塩、過酸化水素、ヒドロパーオキシド系過酸化物から選ばれた酸化性物質の少なくとも1種類以上と、
第一鉄塩系化合物、亜硫酸塩化合物、重亜硫酸塩化合物、有機還元剤から選ばれた還元性物質の少なくとも1種類以上とからなるものであること
を特徴とするものである。
【0015】
さらに、この発明の請求項6に記載の発明は、
請求項1〜5のいずれかに記載の製造法で調製されたこと
を特徴とする水溶性高分子粉末である。
【0016】
さらにまた、この発明の請求項6に記載の発明は、
N−イソプロピルアクリルアミド系単量体を構成単量体とし、残存単量体が100ppm以下であること
を特徴とする水溶性高分子粉末である。
【0017】
【発明の実施の形態】
この発明の感温性を有する水溶性高分子粉末は、N−イソプロピルアクリルアミド又はN−イソプロピルメタクリルアミド(以下、アクリルおよびメタクリルの両者を併せて(メタ)アクリルという。)の単量体単独、あるいはそれらを主体とし、ビニル重合性単量体を含有するN−イソプロピルアクリルアミド系重合体を、特定の条件下で水溶液重合し、得られた重合体を温水で析出することによって得られるものである。
【0018】
すなわち、この発明においては、N−イソプロピル(メタ)アクリルの単量体以外に、熱感応性を損なわない限りにおいて、N−イソプロピル(メタ)アクリルアミドを主体とし、ビニル重合性単量体を含有するものを用いることもできるが、熱感応性が敏感なN−イソプロピル(メタ)アクリルアミド単独の重合体、特にN−イソプロピルアクリルアミド単独の重合体がこの発明にとり好ましいものである。
【0019】
前記のN−イソプロピル(メタ)アクリルアミド以外の、ビニル重合性単量体として用いられるものとしては、水に対して転移温度を持つN−n−プロピル(メタ)アクリルアミド、N−エチル(メタ)アクリルアミド、N−シクロプロピル(メタ)アクリルアミド、N−イソブチル(メタ)アクリルアミド、N−ペンチル(メタ)アクリルアミド、N−シクロヘキシル(メタ)アクリルアミドなどが挙げられる。
【0020】
さらに、例えば、アクリル酸およびその塩、アクリルアミド、N−ビニルピロリドン、イタコン酸およびその塩、マレイン酸およびその塩、メタクリル酸およびその塩、メタクリルアミドなどの水溶性単量体なども挙げられる。
【0021】
これらのビニル重合性単量体は、転移温度の調整などのために使用されるものであるが、熱感応性を損なう傾向があるため、できるだけ少量の使用で済ませることが好ましく、具体的にはN−イソプロピル(メタ)アクリルアミドの100質量部に対して20質量部以下、さらに好ましくは10質量部以下である。
【0022】
この発明におけるN−イソプロピル(メタ)アクリルアミド重合体の製造法としては、前記した単量体群の水溶液重合である。
【0023】
N−イソプロピル(メタ)アクリルアミドの水溶液重合に際しては、水溶液の濃度が重要な反応因子で、例えば、N−イソプロピルアクリルアミド単量体であれば、その水への溶解性は概ね20質量%以上で、概ね温度25℃以下では固液2相に、温度25℃を超えると液液2相となって、均一な重合系が困難となるので、水溶液においてN−イソプロピルアクリルアミド単量体を重合する際の濃度は18質量%以下、10質量%以上であることが好ましく、さらに好ましくは10〜15質量%以下である。単量体濃度が18質量%を越えると単量体の水への溶解に時間が掛り過ぎ、10質量%未満であると重合体の収量が少なくなるため工業的でなく避けるのが望ましい。
【0024】
この発明におけて、N−イソプロピル(メタ)アクリルアミドの重合方法は、前記した単量体の水溶液を、水溶性レドックス開始剤によって重合する方法である。
【0025】
水溶性レドックス開始剤の酸化性物質としては、過硫酸塩、過酸化水素、ヒドロパーオキシド系過酸化物から選ばれた少なくとも1種類以上、還元性物質としては、第一鉄塩系化合物、亜硫酸塩化合物、重亜硫酸塩化合物、アルコール類やポリアミン類などの有機還元剤から選ばれた少なくとも1種類以上とからなるものが好ましい。
【0026】
酸化性物質として、過硫酸の金属塩あるいはアンモニウム塩と、還元性物質として、亜硫酸の金属塩あるいはアンモニウム塩及び/又は重亜硫酸の金属塩あるいはアンモニウム塩の組み合わせが比較的安価で、かつ有機化合物系の水溶性レドックス開始剤に比較して望ましくない分解物が生成しないのでより好ましい。
【0027】
この発明においては、水溶性アゾ系開始剤は、それから生じる分解生成物、反応生成物、未分解残存物などが一般に有毒で、それらを含む重合体の医薬品、医薬部外品、化粧品などの製品への使用は望ましくないものとなるため、この発明においての使用は避けるのが望ましい。
【0028】
この発明における水溶性レドックス開始剤の添加部数としては、単量体総量を100質量部としたとき、酸化性物質は0.01〜1.0質量部が好ましく、酸化性物質が少ないと、単量体に含まれる重合禁止剤や溶存酸素によって重合が阻害されやすく、1.0質量部を超えると重合度が低くなるため好ましくない。
【0029】
さらに、還元性物質の添加部数は、酸化性物質と還元性物質とのモル当量比を好ましくは1.0:1.0〜5.0、より好ましくは1.0:1.5〜3.0になるように調整するもので、還元性物質が少ないと十分なレドックス系が得られず、一方、還元性物質が多いと、例えば、亜硫酸塩あるいは重亜硫酸塩の場合には、残存物により二酸化硫黄が発生し臭気や粘膜への刺激などが生じるため好ましくない。
【0030】
この発明における重合の開始温度は、温度10℃以下にすることが好ましく、より好ましくは温度8℃以下3℃以上に調整するもので、重合開始温度が10℃を超えた状態で重合を開始すると、得られた重合体100質量%に対して残存単量体が100ppmを超えることが多くなり、重合開始温度を3℃未満に制御しても、それに応じた実質的に残留単量体が低減しないので、共に意味の無いことになり好ましくない。
【0031】
また、この発明における重合ピーク温度は、温度40℃以下に制御することが好ましく、さらに温度30℃以下に制御するのが好ましいもので、この重合ピーク温度が温度40℃を超えて制御された場合には、得られた重合体100質量%に対する残存単量体が100ppmを超えることが多くなり好ましくない。一方温度15℃未満に制御しても、残留単量体が実質的に低減しないので、意味の無いことになり好ましくない。
【0032】
重合温度がピークを示した後、外温と同じぐらいになるまで冷却されてほぼ重合が終了した段階で、残存単量体を確実に低減させるため、追加触媒として水溶性レドックス開始剤を加えてもよいが、この場合、同じ開始剤系が望ましく、他の開始剤系を使用しても構わないが、その添加量は重合に使用した部数の半量から1/10程度で十分である。
【0033】
この発明におけるN−イソプロピルアクリルアミド系重合体粉末は、前記の条件で得られた重合体水溶液を、温度40℃以上の温水に投入して析出させて、通常の方法、例えば、加圧、減圧および常圧濾過などによって固液分離した後、通常の乾燥機で乾燥、粉砕させて得ることができる。
【0034】
【実施例】
以下、実施例及び比較例によって、この発明の感温性を有する水溶性高分子粉末とその製造法をさらに具体的に説明する。
なお、調製された重合体粉末の残存単量体及び粘度の測定は、以下の方法によって行った。
【0035】
<残存単量体の測定方法>
0.1gの重合体粉末を10mlの純水に溶解し、この水溶液に10mlのメチルアルコールを加えて重合物を沈殿させて、45μmのフィルターで濾過し、濾液中に存在する単量体を液体クロマトグラフィ(以下、HPLCと略称する。)によって測定した。
HPLCの移動相には、水/メタノール(8/2)溶媒あるいは水/アセトニトリル(8/2)溶媒を使用、検出はUV検出器にて230nmにて行い、標準物質により検量線を求めておき、残量単量体の定量とした。
【0036】
<粘度の測定>
10質量%の水溶液を作製し、ブルッグフィールド粘度計(以下、B型粘度計と略称する。)を用いて測定した。
【0037】
<実施例1>
温度計、窒素導入管、攪拌翼と還流管を取り付けたジャケット付き10リッターのガラス製フラスコに、1.2kgのN−イソプロピルアクリルアミド単量体と、6.8kgのイオン交換水を仕込み、攪拌翼の回転数は100rpm、窒素は1L/minの流量で1時間以上吹き込んだ。
ジャケットに冷水を供給して内温を温度5℃まで冷却し、冷水の供給を止めた後、直ちに、予め調整しておいたペルオキソ硫酸アンモニウム(過硫酸アンモニウム)水溶液と亜硫酸水素ナトリウム(重亜硫酸ナトリウム)水溶液を添加し、窒素を0.2L/minの流量で吹き込み、攪拌翼回転数を100rpmで攪拌を継続した。
おおよそ4時間後にピーク温度(温度29.2℃)に到達し、さらに4時間熟成を行った。
【0038】
前記ペルオキソ硫酸アンモニウム水溶液は、1.8gのペルオキソ硫酸アンモニウムを60gのイオン交換水に溶解して調整し、亜硫酸水素ナトリウム水溶液は、1.8gの亜硫酸水素ナトリウムを60gのイオン交換水に溶解して調整した。
なお、この酸化性物質と還元性物質とのモル比は1.0:2.2である。
【0039】
前記で得られた重合液を、温度約70℃に暖めた大量の純水中に流し込み、重合物を析出沈殿させ、得た沈殿物を温度80℃で12時間乾燥した後、解砕機と粉砕機によって粉末化した。
得られた重合体粉末の10質量%の粘度は350mPa・s、残存単量体は30ppmであった。
【0040】
<実施例2>
実施例1と同様の操作にて重合を実施し、ピーク温度到達後2時間後に、追加触媒として、1gのペルオキソ硫酸アンモニウムと1gの亜硫酸水素ナトリウムを添加し、さらに2時間熟成させた。粉末化など他の操作は実施例1と同様に行った。
得られた重合体粉末の10質量%の粘度は、300mPa・s、残存単量体は10ppmであった。
【0041】
<比較例1>
重合開始の温度を15℃にて実施した以外は、実施例1と同様な操作にて重合体粉末を得た。なお、ピーク温度は約3時間後で、温度41.8℃を記録した。得られた重合体粉末の10質量%の粘度は、180mPa・s、残存単量体は430ppmであった。
【0042】
<比較例2>
重合開始剤として7gの2,2’−アゾビス(2−アミジノプロパン)二塩酸塩を使用して、温度60〜65℃で重合を開始した以外、実施例1と同様の操作にて重合を実施した。
重合開始剤投入直後に重合が開始され、高温のため重合体が析出した。攪拌翼の回転数を300rpmに上げて、10時間、温度60℃で攪拌を継続した。高温の状態のまま、固液分離を行い、実施例と同様な方法にて粉末品を得た。
得られた重合体粉末の10質量%の粘度は、150mPa・s、残存単量体は12,350ppmであった。
【0043】
<比較例3>
溶媒として純水の換わりにメチルアルコールを使用した。開始剤は2,2’−アゾビス(2,4−ジメチルバレロニトリル)を1.2g使用して、メチルアルコールの還流温度で、10時間重合した。重合液を冷却後、10倍量の温度60℃の温水に投入して、重合体を析出させ、固液分離した後、同様に粉末化した。得られた重合体粉末の10質量%の粘度は、250mPa・s、残存単量体は7,970ppmであった。
さらに、この10gの得られた重合体粉末を50mlのメチルアルコールに再溶解させて、10倍量の温度60℃の温水に投入して、再度析出させ、同様に粉末化した。
得られた重合体粉末の残存単量体は630ppmであった。
【0044】
【発明の効果】
この発明によれば、N−イソプロピルアクリルアミドを主体とする単量体水溶液を水溶性レドックス開始剤により、重合ピーク温度を40℃以下で、特に重合開始温度を10℃以下にして重合することによって、残存単量体が100ppm以下のN−イソプロピルアクリルアミド重合体粉末が得られる。
【0045】
得られる残存単量体の少ないN−イソプロピルアクリルアミドを主たる単量体とする重合体は、感温性を有する水溶性高分子で、感温性遮光体、温度センサー、湿度センサー、感温性水性ゲル、化粧料添加物、医薬徐放性担体、皮膚貼付剤添加物などに良好に使用され得るものである。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is a water-soluble, temperature-sensitive water-soluble body used for temperature-sensitive light-shielding bodies, temperature sensors, humidity sensors, temperature-sensitive aqueous gels, cosmetic additives, pharmaceutical sustained-release carriers, skin patch additives, and the like. The present invention relates to a polymer powder, more particularly, to an N-isopropylacrylamide polymer powder and a method for producing the same.
[0002]
[Prior art]
An N-isopropylacrylamide-based polymer having N-isopropylacrylamide or N-isopropylmethacrylamide as a main constituent monomer, for example, an N-isopropylacrylamide polymer has a transition temperature of about 32 ° C. Although it has a property, it has a special reversible property that it precipitates in a high-temperature region, and is attracting attention as a temperature-sensitive material.
[0003]
As a method for producing a polymer containing N-isopropylacrylamide or N-isopropylmethacrylamide as a main constituent monomer, a method such as reverse phase suspension polymerization or precipitation polymerization in addition to aqueous solution polymerization is known.
[0004]
For example, Japanese Patent Application Laid-Open No. 2000-230008 discloses an aqueous solution polymerization method using an azo-based initiator, and Japanese Patent Publication No. 04-68321 discloses a precipitation polymerization using a benzene solvent. JP-A-60-120710 discloses precipitation polymerization using an alkyl acetate solvent, and JP-A-60-120710 discloses reverse phase suspension polymerization.
[0005]
[Problems to be solved by the invention]
However, the N-isopropylacrylamide-based polymer obtained by the reversed-phase suspension polymerization or the precipitation polymerization contains the solvent used for the polymerization, and even after powdering, the residual solvent is completely removed. This residual solvent has a drawback that the content of the residual monomer is a serious problem in certain applications.
[0006]
In addition, in the method by aqueous solution polymerization, although there is no problem of the residual solvent, there is generally a tendency that the residual monomer is large, and the temperature-sensitive aqueous gel, cosmetic additive, pharmaceutical sustained release carrier, skin patch When used as an additive for additives, etc., one of the major requirements is that the amount of residual monomers is small. Therefore, it is required to reduce residual monomers in a polymer by aqueous solution polymerization.
[0007]
Therefore, Japanese Patent Application Laid-Open No. 08-59709 discloses that a polymer having a small amount of residual monomer is obtained by polymerizing an N-substituted acrylamide-based monomer in isopropyl acetate using a water-soluble initiator and then removing the solvent. Is disclosed, but the amount of residual monomer is on the order of several hundreds to several thousands, which is still insufficient.
[0008]
In view of such circumstances, the present invention provides an N-isopropylacrylamide-based polymer powder as a temperature-sensitive water-soluble polymer having N-isopropylacrylamide or N-isopropylmethacrylamide as a main monomer having few residual monomers. We considered to do it.
[0009]
As a result, an N-isopropylacrylamide-based monomer is subjected to aqueous solution polymerization under specific conditions, and the resulting polymer is precipitated with warm water. The inventors have found that the present invention can be obtained and completed the present invention.
[0010]
[Means for Solving the Problems]
That is, the invention described in claim 1 of the present invention
A method for producing a water-soluble polymer powder, comprising polymerizing an N-isopropylacrylamide-based monomer in an aqueous solution using a water-soluble redox initiator, and precipitating the resulting polymer with warm water of 40 ° C. or more. .
[0011]
The invention described in claim 2 of the present invention
The method for producing a water-soluble polymer powder according to claim 1,
The N-isopropylacrylamide-based monomer,
It is characterized by being N-isopropylacrylamide or N-isopropylmethacrylamide.
[0012]
Further, the invention described in claim 3 of the present invention is:
The method for producing a water-soluble polymer powder according to claim 1,
The N-isopropylacrylamide-based monomer,
It is mainly characterized in that it is mainly composed of N-isopropylacrylamide or N-isopropylmethacrylamide and contains a vinyl polymerizable monomer.
[0013]
Further, the invention described in claim 4 of the present invention is:
The method for producing a water-soluble polymer powder according to claim 2,
The aqueous solution polymerization,
The concentration of N-isopropylacrylamide in an aqueous solution is 18% by mass or less, the polymerization initiation temperature is 10C or less, and the polymerization peak temperature is 40C or less.
[0014]
Further, the invention according to claim 5 of the present invention provides:
The method for producing a water-soluble polymer powder according to claim 1,
The water-soluble redox initiator,
At least one or more oxidizing substances selected from persulfates, hydrogen peroxide, and hydroperoxides;
It is characterized by comprising at least one or more reducing substances selected from ferrous salt compounds, sulfite compounds, bisulfite compounds, and organic reducing agents.
[0015]
Further, the invention described in claim 6 of the present invention is:
A water-soluble polymer powder prepared by the production method according to claim 1.
[0016]
Furthermore, the invention according to claim 6 of the present invention provides:
A water-soluble polymer powder comprising an N-isopropylacrylamide-based monomer as a constituent monomer and a residual monomer of 100 ppm or less.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
The temperature-sensitive water-soluble polymer powder of the present invention may be a monomer of N-isopropylacrylamide or N-isopropylmethacrylamide (hereinafter, both acryl and methacryl are collectively referred to as (meth) acryl), or It is obtained by subjecting an N-isopropylacrylamide-based polymer containing these as a main component and containing a vinyl polymerizable monomer to aqueous solution polymerization under specific conditions, and precipitating the obtained polymer with warm water.
[0018]
That is, in the present invention, in addition to the N-isopropyl (meth) acrylic monomer, as long as the heat sensitivity is not impaired, the composition mainly contains N-isopropyl (meth) acrylamide and contains a vinyl polymerizable monomer. Although a polymer can be used, a polymer of N-isopropyl (meth) acrylamide alone, which is sensitive to heat, particularly a polymer of N-isopropylacrylamide alone is preferable for the present invention.
[0019]
Other than the above-mentioned N-isopropyl (meth) acrylamide, those used as vinyl polymerizable monomers include Nn-propyl (meth) acrylamide and N-ethyl (meth) acrylamide having a transition temperature with respect to water. , N-cyclopropyl (meth) acrylamide, N-isobutyl (meth) acrylamide, N-pentyl (meth) acrylamide, N-cyclohexyl (meth) acrylamide and the like.
[0020]
Further, for example, water-soluble monomers such as acrylic acid and its salts, acrylamide, N-vinylpyrrolidone, itaconic acid and its salts, maleic acid and its salts, methacrylic acid and its salts, and methacrylamide are also included.
[0021]
These vinyl polymerizable monomers are used for adjusting the transition temperature and the like, but since they tend to impair the heat sensitivity, it is preferable to use as little as possible, specifically, It is at most 20 parts by mass, more preferably at most 10 parts by mass, based on 100 parts by mass of N-isopropyl (meth) acrylamide.
[0022]
The method for producing the N-isopropyl (meth) acrylamide polymer in the present invention is an aqueous solution polymerization of the above-mentioned monomer group.
[0023]
In the polymerization of an aqueous solution of N-isopropyl (meth) acrylamide, the concentration of the aqueous solution is an important reaction factor. For example, in the case of an N-isopropylacrylamide monomer, its solubility in water is about 20% by mass or more. When the temperature is approximately 25 ° C. or lower, a solid-liquid two phase is formed. When the temperature exceeds 25 ° C., a liquid-liquid two phase is formed, and a uniform polymerization system becomes difficult. The concentration is preferably 18% by mass or less, 10% by mass or more, more preferably 10 to 15% by mass. When the monomer concentration exceeds 18% by mass, it takes too much time to dissolve the monomer in water, and when the monomer concentration is less than 10% by mass, the yield of the polymer is reduced.
[0024]
In the present invention, the method for polymerizing N-isopropyl (meth) acrylamide is a method in which an aqueous solution of the above-mentioned monomer is polymerized with a water-soluble redox initiator.
[0025]
The oxidizing substance of the water-soluble redox initiator is at least one selected from persulfates, hydrogen peroxide and hydroperoxides, and the reducing substances are ferrous compounds and sulfurous acids. It is preferable to use at least one selected from salt compounds, bisulfite compounds, and organic reducing agents such as alcohols and polyamines.
[0026]
A combination of a metal salt or ammonium salt of persulfuric acid as an oxidizing substance and a metal salt or ammonium salt of sulfurous acid as a reducing substance and / or a metal salt or ammonium salt of bisulfite is relatively inexpensive and an organic compound-based compound. This is more preferable because undesirable decomposition products are not produced as compared with the water-soluble redox initiator of the above.
[0027]
In the present invention, the water-soluble azo initiator is generally toxic to decomposition products, reaction products, undecomposed residues, and the like resulting therefrom, and contains polymers such as pharmaceuticals, quasi-drugs, and cosmetics. It is desirable to avoid using it in the present invention, as its use is undesirable.
[0028]
The amount of the water-soluble redox initiator to be added in the present invention is preferably 0.01 to 1.0 part by mass when the total amount of the monomers is 100 parts by mass. The polymerization is liable to be inhibited by the polymerization inhibitor and dissolved oxygen contained in the monomer, and if it exceeds 1.0 part by mass, the degree of polymerization is undesirably low.
[0029]
Further, the number of parts of the reducing substance to be added is preferably such that the molar equivalent ratio of the oxidizing substance to the reducing substance is 1.0: 1.0 to 5.0, more preferably 1.0: 1.5 to 3.0. In the case where the amount of the reducing substance is small, a sufficient redox system cannot be obtained. On the other hand, when the amount of the reducing substance is large, for example, in the case of sulfite or bisulfite, depending on the residue, It is not preferable because sulfur dioxide is generated, causing odor and irritation to mucous membranes.
[0030]
In the present invention, the polymerization initiation temperature is preferably adjusted to a temperature of 10 ° C. or lower, more preferably to a temperature of 8 ° C. or lower and 3 ° C. or higher. When the polymerization is started in a state where the polymerization initiation temperature exceeds 10 ° C. In many cases, the residual monomer exceeds 100 ppm with respect to 100% by mass of the obtained polymer, and even if the polymerization initiation temperature is controlled to less than 3 ° C., the residual monomer is substantially reduced accordingly. It is not preferable because both are meaningless.
[0031]
Further, the polymerization peak temperature in the present invention is preferably controlled at a temperature of 40 ° C. or lower, and more preferably at a temperature of 30 ° C. or lower. When the polymerization peak temperature is controlled at a temperature higher than 40 ° C. However, the amount of residual monomer relative to 100% by mass of the obtained polymer often exceeds 100 ppm, which is not preferable. On the other hand, if the temperature is controlled to be lower than 15 ° C., the residual monomer is not substantially reduced, so that it has no meaning and is not preferable.
[0032]
After the polymerization temperature showed a peak, it was cooled down to about the same as the external temperature, and at the stage when the polymerization was almost completed, a water-soluble redox initiator was added as an additional catalyst to reliably reduce residual monomers. However, in this case, the same initiator system is desirable, and other initiator systems may be used. However, the addition amount is about 1/10 to half of the number of parts used for the polymerization.
[0033]
The N-isopropylacrylamide-based polymer powder in the present invention is prepared by throwing the polymer aqueous solution obtained under the above conditions into warm water at a temperature of 40 ° C. or higher to precipitate the solution, using a usual method, for example, pressurizing, depressurizing and After solid-liquid separation by normal pressure filtration or the like, it can be obtained by drying and pulverizing with a usual dryer.
[0034]
【Example】
Hereinafter, the water-soluble polymer powder having temperature sensitivity of the present invention and a method for producing the same will be described more specifically with reference to Examples and Comparative Examples.
The residual monomer and viscosity of the prepared polymer powder were measured by the following methods.
[0035]
<Method for measuring residual monomer>
0.1 g of the polymer powder was dissolved in 10 ml of pure water, and 10 ml of methyl alcohol was added to the aqueous solution to precipitate a polymer, which was filtered through a 45 μm filter. It was measured by chromatography (hereinafter abbreviated as HPLC).
Water / methanol (8/2) solvent or water / acetonitrile (8/2) solvent was used for the mobile phase of HPLC. Detection was performed at 230 nm with a UV detector, and a calibration curve was obtained using a standard substance. And the amount of residual monomer was determined.
[0036]
<Measurement of viscosity>
A 10% by mass aqueous solution was prepared and measured using a Brookfield viscometer (hereinafter abbreviated as a B-type viscometer).
[0037]
<Example 1>
A jacketed 10-liter glass flask equipped with a thermometer, a nitrogen inlet tube, a stirring blade and a reflux tube was charged with 1.2 kg of N-isopropylacrylamide monomer and 6.8 kg of ion-exchanged water. Was rotated at 100 rpm, and nitrogen was blown at a flow rate of 1 L / min for 1 hour or more.
Cool water is supplied to the jacket to cool the internal temperature to a temperature of 5 ° C., and the supply of cold water is stopped. Was added, nitrogen was blown in at a flow rate of 0.2 L / min, and stirring was continued at a stirring blade rotation speed of 100 rpm.
Approximately 4 hours later, the peak temperature (temperature: 29.2 ° C.) was reached, and aging was performed for another 4 hours.
[0038]
The aqueous solution of ammonium peroxosulfate was prepared by dissolving 1.8 g of ammonium peroxosulfate in 60 g of ion-exchanged water, and the aqueous solution of sodium bisulfite was prepared by dissolving 1.8 g of sodium bisulfite in 60 g of ion-exchanged water. .
The molar ratio between the oxidizing substance and the reducing substance is 1.0: 2.2.
[0039]
The polymerization solution obtained above is poured into a large amount of pure water warmed to a temperature of about 70 ° C. to precipitate and precipitate a polymer. The obtained precipitate is dried at a temperature of 80 ° C. for 12 hours, and then crushed with a crusher. Powdered by machine.
The viscosity of 10% by mass of the obtained polymer powder was 350 mPa · s, and the residual monomer was 30 ppm.
[0040]
<Example 2>
Polymerization was carried out in the same manner as in Example 1. Two hours after the peak temperature was reached, 1 g of ammonium peroxosulfate and 1 g of sodium bisulfite were added as additional catalysts, and the mixture was further aged for 2 hours. Other operations such as powdering were performed in the same manner as in Example 1.
The viscosity of 10% by mass of the obtained polymer powder was 300 mPa · s, and the residual monomer was 10 ppm.
[0041]
<Comparative Example 1>
A polymer powder was obtained in the same manner as in Example 1, except that the temperature at the start of polymerization was 15 ° C. In addition, about 3 hours after the peak temperature, a temperature of 41.8 ° C. was recorded. The viscosity of 10% by mass of the obtained polymer powder was 180 mPa · s, and the residual monomer was 430 ppm.
[0042]
<Comparative Example 2>
Polymerization was carried out in the same manner as in Example 1 except that the polymerization was started at a temperature of 60 to 65 ° C. using 7 g of 2,2′-azobis (2-amidinopropane) dihydrochloride as a polymerization initiator. did.
Polymerization was started immediately after the addition of the polymerization initiator, and the polymer was precipitated due to the high temperature. The rotation speed of the stirring blade was increased to 300 rpm, and stirring was continued at a temperature of 60 ° C. for 10 hours. Solid-liquid separation was performed while the temperature was high, and a powder product was obtained in the same manner as in the example.
The viscosity of the obtained polymer powder at 10% by mass was 150 mPa · s, and the residual monomer was 12,350 ppm.
[0043]
<Comparative Example 3>
Methyl alcohol was used as a solvent instead of pure water. As an initiator, 1.2 g of 2,2′-azobis (2,4-dimethylvaleronitrile) was used, and polymerized for 10 hours at the reflux temperature of methyl alcohol. After cooling, the polymer solution was poured into a 10-fold amount of hot water at a temperature of 60 ° C. to precipitate a polymer. The polymer was separated into solid and liquid, and then powdered in the same manner. The viscosity of the obtained polymer powder at 10% by mass was 250 mPa · s, and the residual monomer was 7,970 ppm.
Further, 10 g of the obtained polymer powder was redissolved in 50 ml of methyl alcohol, and poured into 10 times the amount of hot water at a temperature of 60 ° C. to precipitate again, and powdered similarly.
The residual monomer in the obtained polymer powder was 630 ppm.
[0044]
【The invention's effect】
According to the present invention, a monomer aqueous solution mainly composed of N-isopropylacrylamide is polymerized with a water-soluble redox initiator at a polymerization peak temperature of 40 ° C. or lower, particularly at a polymerization start temperature of 10 ° C. or lower, An N-isopropylacrylamide polymer powder having a residual monomer of 100 ppm or less is obtained.
[0045]
The obtained polymer containing N-isopropylacrylamide as a main monomer having a small amount of residual monomers is a water-soluble polymer having a temperature sensitivity, and is a temperature-sensitive light shield, a temperature sensor, a humidity sensor, and a temperature-sensitive aqueous solution. It can be suitably used for gels, cosmetic additives, pharmaceutical sustained-release carriers, skin patch additives and the like.
Claims (7)
を特徴とする水溶性高分子粉末の製造法。A method for producing a water-soluble polymer powder, comprising subjecting an N-isopropylacrylamide-based monomer to aqueous solution polymerization using a water-soluble redox initiator, and precipitating the resulting polymer with warm water of 40 ° C or higher.
N−イソプロピルアクリルアミド又はN−イソプロピルメタアクリルアミドであること
を特徴とする請求項1に記載の水溶性高分子粉末の製造法。The N-isopropylacrylamide-based monomer,
The method for producing a water-soluble polymer powder according to claim 1, wherein the method is N-isopropylacrylamide or N-isopropylmethacrylamide.
N−イソプロピルアクリルアミド又はN−イソプロピルメタアクリルアミドを主体とし、ビニル重合性単量体を含有するものであること
を特徴とする請求項1に記載の水溶性高分子粉末の製造法。The N-isopropylacrylamide-based monomer,
The method for producing a water-soluble polymer powder according to claim 1, wherein the method mainly comprises N-isopropylacrylamide or N-isopropylmethacrylamide and contains a vinyl polymerizable monomer.
N−イソプロピルアクリルアミドの水溶液中の濃度を、18質量%以下、重合開始温度を10℃以下、重合ピーク温度を40℃以下の条件下に行うこと
を特徴とする請求項2に記載の水溶性高分子粉末の製造法。The aqueous solution polymerization,
3. The method according to claim 2, wherein the concentration of N-isopropylacrylamide in the aqueous solution is 18% by mass or less, the polymerization initiation temperature is 10C or less, and the polymerization peak temperature is 40C or less. Manufacturing method of molecular powder.
過硫酸塩、過酸化水素、ヒドロパーオキシド系過酸化物から選ばれた酸化性物質の少なくとも1種類以上と、
第一鉄塩系化合物、亜硫酸塩化合物、重亜硫酸塩化合物、有機還元剤から選ばれた還元性物質の少なくとも1種類以上とからなるものであること
を特徴とする請求項1又は2に記載の水溶性高分子粉末の製造法。The water-soluble redox initiator,
At least one or more oxidizing substances selected from persulfates, hydrogen peroxide, and hydroperoxides;
3. The method according to claim 1, comprising at least one reducing substance selected from a ferrous salt compound, a sulfite compound, a bisulfite compound, and an organic reducing agent. 4. Manufacturing method of water-soluble polymer powder.
を特徴とする水溶性高分子粉末。A water-soluble polymer powder prepared by the production method according to claim 1.
を特徴とする水溶性高分子粉末。A water-soluble polymer powder comprising an N-isopropylacrylamide-based monomer as a constituent monomer and a residual monomer of 100 ppm or less.
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JP2010196048A (en) * | 2009-01-30 | 2010-09-09 | Kose Corp | Novel water-soluble polymer, and cosmetic material or skin preparation for external use containing the same |
JP2010254974A (en) * | 2009-03-31 | 2010-11-11 | Kose Corp | Water-soluble copolymer and cosmetic or external preparation for skin obtained by blending the same |
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