JPH07278212A - Production of aqueous emulsion - Google Patents
Production of aqueous emulsionInfo
- Publication number
- JPH07278212A JPH07278212A JP6930794A JP6930794A JPH07278212A JP H07278212 A JPH07278212 A JP H07278212A JP 6930794 A JP6930794 A JP 6930794A JP 6930794 A JP6930794 A JP 6930794A JP H07278212 A JPH07278212 A JP H07278212A
- Authority
- JP
- Japan
- Prior art keywords
- polymerization
- emulsion
- mercapto group
- pva
- polyvinyl alcohol
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F2/00—Processes of polymerisation
- C08F2/12—Polymerisation in non-solvents
- C08F2/16—Aqueous medium
- C08F2/22—Emulsion polymerisation
- C08F2/24—Emulsion polymerisation with the aid of emulsifying agents
- C08F2/30—Emulsion polymerisation with the aid of emulsifying agents non-ionic
Landscapes
- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Graft Or Block Polymers (AREA)
- Polymerisation Methods In General (AREA)
- Polymerization Catalysts (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は水性エマルジョンの製造
方法に関する。FIELD OF THE INVENTION The present invention relates to a method for producing an aqueous emulsion.
【０００２】[0002]
【従来の技術及び発明が解決しようとする課題】従来、
スチレン−ブタジエン共重合体エマルジョン、（メタ）
アクリル酸エステル系樹脂エマルジョン、ビニルエステ
ル系樹脂エマルジョン等のエチレン性不飽和単量体やジ
エン系単量体を単独または共重合して得られる合成樹脂
エマルジョンは、紙の顔料コーティング用バインダーや
繊維加工剤、粘着剤、接着剤、塗料、モルタル混和剤等
の広範な用途に用いられている。2. Description of the Related Art Conventionally, the problems to be solved by the invention
Styrene-butadiene copolymer emulsion, (meth)
Synthetic resin emulsions obtained by homopolymerizing or copolymerizing ethylenically unsaturated monomers and diene monomers such as acrylic acid ester-based resin emulsions and vinyl ester-based resin emulsions are used as binders for pigment coating of paper and fiber processing. It is used in a wide range of applications such as adhesives, adhesives, adhesives, paints, and mortar admixtures.
【０００３】また、上記合成樹脂エマルジョンは、エチ
レン性不飽和単量体及び／又はジエン系単量体を界面活
性剤の存在下で乳化重合して得られる場合と、ポリビニ
ルアルコールやヒドロキシエチルセルロース等の水溶性
高分子の存在下で乳化重合して得られる場合の２通りに
大別される。前者は、界面活性剤を使用することに起因
する多くの問題点を有している。すなわち、エマルジョ
ンの放置安定性、機械的安定性、化学的安定性、凍結融
解安定性や顔料混和性等が不充分であり、一般的にエマ
ルジョンの粘度が低いために比較的高粘度が要求される
接着剤などの用途の場合には、増粘剤の添加や不飽和酸
の共重合によるアルカリ増粘等の方法を採らざるを得な
いことから、最終物性への悪影響があり、さらに界面活
性剤のマイグレーションによる接着阻害が生じることが
多い。界面活性剤を用いる乳化重合法の問題点に対して
は、反応性（共重合性）乳化剤を用いる方法やソープフ
リー重合法等の種々の重合法が検討されているが、処方
的な制限が多いために実用化されている例は少ない。Further, the above synthetic resin emulsion is obtained by emulsion polymerization of an ethylenically unsaturated monomer and / or diene monomer in the presence of a surfactant, and polyvinyl alcohol and hydroxyethyl cellulose. It is roughly classified into two types when it is obtained by emulsion polymerization in the presence of a water-soluble polymer. The former has many problems resulting from the use of surfactants. That is, the leaving stability, mechanical stability, chemical stability, freeze-thaw stability, pigment miscibility, etc. of the emulsion are insufficient, and relatively high viscosity is generally required because the viscosity of the emulsion is low. In the case of applications such as adhesives, it is necessary to use methods such as addition of a thickener and alkali thickening by copolymerization of unsaturated acids, which has a negative effect on the final physical properties and further increases surface activity. Adhesion is often hindered by migration of the agent. Regarding the problems of the emulsion polymerization method using a surfactant, various polymerization methods such as a method using a reactive (copolymerizable) emulsifier and a soap-free polymerization method have been studied, but there are prescriptive limitations. Because of the large number, few are in practical use.
【０００４】一方、後者に関しては、酢酸ビニル系や塩
化ビニル系の乳化重合において、ポリビニルアルコール
系重合体を乳化分散安定剤として製造したエマルジョン
は、機械的安定性、化学的安定性、凍結融解安定性、顔
料混和性等の分散安定性に優れ、重合処方により所望の
粘度のエマルジョンが得られる等の特徴を有しており、
広く実用化されている。しかしながら、この場合、ＰＶ
Ａへのグラフト反応がエマルジョンの安定性に関係して
いると考えられており、対象は、もっぱらラジカル反応
性の大きい酢酸ビニルや塩化ビニルに限られていて、ラ
ジカル反応性の小さいスチレンやブタジエン等のジエン
系単量体や（メタ）アクリル酸エステル系単量体に対し
ては、ＰＶＡを用いても安定なエマルジョンが得られな
いという問題があった。このような問題に対して、特開
昭６０−１９７２２９号にメルカプト基を有するポリビ
ニルアルコール系重合体をこれらの乳化分散安定剤に用
いることが提案されている。この場合、通常用いられる
開始剤、例えば、過硫酸カリウム、過硫酸アンモニウ
ム、過硫化水素単独あるいはこれらと各種還元剤との組
み合わせによるレドックス系開始剤等の熱分解によりラ
ジカルを発生する開始剤では、メルカプト基を有するＰ
ＶＡへのグラフト反応は起こるものの、その効率が悪い
ために実用上、充分な安定性の確保が難しいという問題
があり、一方、熱分解による自己ラジカル発生能を有さ
ず、メルカプト基含有ＰＶＡのメルカプト基とのレドッ
クス反応でＰＶＡ分子末端にラジカルを発生させる臭素
酸カリウム等の開始剤では、グラフト反応の効率が非常
に高く実用上充分な安定性を有するエマルジョンが得ら
れるが、メルカプト基含有ＰＶＡ中のメルカプト基含有
量が限られるため、Ｄｅａｄ−Ｅｎｄとなり高重合率ま
で重合が進行せず単量体濃度が高い重合系に熱分解型の
開始剤を追加する等の操作を必要とすることから、除熱
の問題等で実用的な規模での製造が難しいという欠点が
あった。On the other hand, regarding the latter, in the vinyl acetate-based or vinyl chloride-based emulsion polymerization, an emulsion produced by using a polyvinyl alcohol-based polymer as an emulsion dispersion stabilizer has mechanical stability, chemical stability, and freeze-thaw stability. , Excellent dispersion stability such as pigment miscibility, and the like that an emulsion having a desired viscosity can be obtained by a polymerization formulation.
Widely used in practice. However, in this case, PV
It is considered that the graft reaction to A is related to the stability of the emulsion, and the target is limited to vinyl acetate and vinyl chloride, which have large radical reactivity, and styrene and butadiene, which have small radical reactivity. With respect to the diene-based monomer and the (meth) acrylic acid ester-based monomer, there was a problem that a stable emulsion could not be obtained even if PVA was used. To solve such problems, JP-A-60-1972229 proposes to use a polyvinyl alcohol-based polymer having a mercapto group for these emulsion dispersion stabilizers. In this case, a commonly used initiator such as potassium persulfate, ammonium persulfate, hydrogen persulfate alone or an initiator that generates a radical by thermal decomposition such as a redox initiator by a combination of these with various reducing agents is mercapto. P having a group
Although the graft reaction to VA occurs, there is a problem in that it is difficult to secure sufficient stability in practice due to its poor efficiency. On the other hand, it does not have the ability to generate a self-radical by thermal decomposition, and thus the mercapto group-containing PVA has a problem. With an initiator such as potassium bromate that generates radicals at the terminal of PVA molecule by redox reaction with a mercapto group, an emulsion having very high graft reaction efficiency and sufficient practical stability can be obtained. Since the content of the mercapto group in the product is limited, it becomes Dead-End and the polymerization does not proceed to a high polymerization rate, and it is necessary to perform an operation such as adding a thermal decomposition type initiator to the polymerization system in which the monomer concentration is high. Therefore, there is a drawback that it is difficult to manufacture on a practical scale due to the problem of heat removal.
【０００５】[0005]
【課題を解決するための手段】本発明者らは、上記の実
情に鑑み、鋭意検討した結果、メルカプト基を有するポ
リビニルアルコール系重合体を分散剤として用い、該ポ
リビニルアルコール系重合体のメルカプト基とのレドッ
クス反応によってのみラジカルを発生させる特定の開始
剤を用いた乳化重合において、メルカプト基を有するポ
リビニルアルコールを乳化重合時に連続的、あるいは間
欠的に重合系に添加することを特徴とする水性エマルジ
ョンの製造方法が、格段に優れた安定性を有し、かつ該
ポリビニルアルコール系重合体の分散質への化学結合
（グラフト）率の高いラジカル重合可能なエチレン性不
飽和単量体及びジエン系不飽和単量体からなる重合体の
水性エマルジョンを実用的、工業的規模で製造する優れ
た方法であることを見出し、本発明を完成するに至っ
た。Means for Solving the Problems The inventors of the present invention have made earnest studies in view of the above circumstances, and as a result, a polyvinyl alcohol polymer having a mercapto group was used as a dispersant, and the mercapto group of the polyvinyl alcohol polymer was used. In an emulsion polymerization using a specific initiator that generates a radical only by a redox reaction with, an aqueous emulsion characterized by adding a polyvinyl alcohol having a mercapto group continuously or intermittently to the polymerization system during the emulsion polymerization. The method for producing the same has a radically polymerizable ethylenically unsaturated monomer and a diene-based unsaturated monomer, which have remarkably excellent stability and have a high rate of chemical bonding (grafting) to the dispersoid of the polyvinyl alcohol-based polymer. It is an excellent method for producing an aqueous emulsion of a polymer composed of saturated monomers on a practical and industrial scale. Out, it has led to the completion of the present invention.
【０００６】すなわち、本発明の目的は、安定性に優
れ、かつポリビニルアルコール系重合体の分散質への化
学結合（グラフト）率の高い水性エマルジョンを実用
的、工業的規模で製造しようというものであり、ラジカ
ル反応において極めて活性なメルカプト基を導入したポ
リビニルアルコール系重合体を分散剤として用い、該ポ
リビニルアルコール系重合体のメルカプト基とのレドッ
クス反応によってのみラジカルを発生させる特定の開始
剤を用いた乳化重合により、該ポリビニルアルコール系
重合体の分散質への化学結合（グラフト）率を向上さ
せ、しかも、該ポリビニルアルコール系重合体を乳化重
合時に、連続的あるいは間欠的に重合系に添加すること
により、高転化率までスムースに重合が進行するとい
う、実用的、工業的に極めて有効な水性エマルジョンの
製造方法を提供しようとするものである。That is, the object of the present invention is to produce an aqueous emulsion which is excellent in stability and has a high chemical bond (grafting) ratio to a dispersoid of a polyvinyl alcohol polymer on a practical and industrial scale. There, using a polyvinyl alcohol-based polymer introduced a very active mercapto group in a radical reaction as a dispersant, using a specific initiator that generates a radical only by a redox reaction with the mercapto group of the polyvinyl alcohol-based polymer Improving the chemical bond (grafting) ratio of the polyvinyl alcohol polymer to the dispersoid by emulsion polymerization, and further, continuously or intermittently adding the polyvinyl alcohol polymer to the polymerization system during emulsion polymerization. This allows the polymerization to proceed smoothly up to a high conversion rate, which is extremely practical and industrial. It is intended to provide a method of manufacturing a valid aqueous emulsion.
【０００７】本発明の水性エマルジョンの製造方法にお
いて、分散質を構成するエチレン性不飽和単量体単位及
びジエン系単量体単位としては、ラジカル重合可能なも
のであれば特に制限はなく、（メタ）アクリル酸エステ
ル系単量体、ビニルエステル系単量体、スチレン系単量
体、ハロゲン化不飽和単量体、オレフィン系単量体、ジ
エン系単量体等が挙げられる。ここで（メタ）アクリル
酸エステル系単量体としては、好ましくは炭素数１〜１
２のアルキル基を有する単量体単位、例えば、（メタ）
アクリル酸メチル、（メタ）アクリル酸エチル、（メ
タ）アクリル酸プロピル、（メタ）アクリル酸ブチル、
（メタ）アクリル酸２−エチルヘキシル、（メタ）アク
リル酸ドデシル、（メタ）アクリル酸ジメチルアミノエ
チル及びこれらの四級化物、（メタ）アクリルアミド、
Ｎ，Ｎ−ジメチル（メタ）アクリルアミド、（メタ）ア
クリルアミド−２−メチルプロピルスルホ酸およびその
ナトリウム塩、（メタ）アクリル酸ヒドロキシエチル、
カプロラクトン変性（メタ）アクリル酸エステル、Ｎ−
メチロール（メタ）アクリルアミド等のα−β−エチレ
ン性不飽和カルボン酸のＮ−アルキロールアミド類、エ
チレングリコール（メタ）アクリレートなどが挙げられ
る。また、ビニルエステル系単量体としては、ギ酸ビニ
ル、酢酸ビニル、プロピオン酸ビニル、バーサチック酸
ビニル、ピバリン酸ビニルなどが挙げられる。スチレン
系単量体としては、好ましくは、スチレン、α−メチル
スチレン、Ｏ−メチルスチレン、Ｐ−メチルスチレン、
Ｐ−スチレンスルホン酸およびそのアルカリ金属塩（ナ
トリウム塩、カリウム塩等）などがある。In the method for producing an aqueous emulsion of the present invention, the ethylenically unsaturated monomer unit and the diene monomer unit constituting the dispersoid are not particularly limited as long as they are radically polymerizable. Examples thereof include (meth) acrylic acid ester-based monomers, vinyl ester-based monomers, styrene-based monomers, halogenated unsaturated monomers, olefin-based monomers, and diene-based monomers. Here, the (meth) acrylic acid ester-based monomer preferably has 1 to 1 carbon atoms.
A monomer unit having 2 alkyl groups, eg (meth)
Methyl acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate,
2-Ethylhexyl (meth) acrylate, dodecyl (meth) acrylate, dimethylaminoethyl (meth) acrylate and quaternary products thereof, (meth) acrylamide,
N, N-dimethyl (meth) acrylamide, (meth) acrylamido-2-methylpropyl sulfonic acid and its sodium salt, hydroxyethyl (meth) acrylate,
Caprolactone-modified (meth) acrylic acid ester, N-
Examples include α-β-ethylenically unsaturated carboxylic acid N-alkylolamides such as methylol (meth) acrylamide, ethylene glycol (meth) acrylate, and the like. Examples of vinyl ester-based monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl versatate, vinyl pivalate, and the like. The styrene-based monomer is preferably styrene, α-methylstyrene, O-methylstyrene, P-methylstyrene,
P-styrene sulfonic acid and its alkali metal salts (sodium salt, potassium salt, etc.) and the like.
【０００８】また、ハロゲン化不飽和単量体としては、
塩化ビニル、フッ化ビニル、塩化ビニリデン、フッ化ビ
ニリデン、臭化ビニリデン等が挙げられる。オレフィン
系単量体としては、エチレン、プロピレン、イソブチレ
ン等が挙げられる。また、ジエン系単量体としては、例
えば、ブタジエン、イソプレン、クロロプレン、ネオプ
レン等が好適である。また、（メタ）アクリル酸、イタ
コン酸、フマル酸、マレイン酸等の不飽和カルボン酸及
びその塩等も共重合可能である。As the halogenated unsaturated monomer,
Examples thereof include vinyl chloride, vinyl fluoride, vinylidene chloride, vinylidene fluoride and vinylidene bromide. Examples of the olefin-based monomer include ethylene, propylene and isobutylene. Further, as the diene-based monomer, for example, butadiene, isoprene, chloroprene, neoprene and the like are suitable. Further, unsaturated carboxylic acids such as (meth) acrylic acid, itaconic acid, fumaric acid and maleic acid, and salts thereof can be copolymerized.
【０００９】また、本発明の水性エマルジョンの製造方
法において、分散剤としては、メルカプト基を有するポ
リビニルアルコール系重合体が用いられる。メルカプト
基を有するＰＶＡ系重合体として、重合体の主鎖中にメ
ルカプト基を有するＰＶＡ系重合体を用いても良いが、
このものは、ＰＶＡ自体の酸化によりジスルフィド結合
を形成して不溶化する恐れがあるので分子片末端のみに
メルカプト基を有するＰＶＡ系重合体が、不溶化の心配
がなく取扱いが容易であることから好ましい。なお、本
発明で使用する末端にメルカプト基を有するＰＶＡ系重
合体は、末端のメルカプト基以外に、ＰＶＡ系重合体の
主鎖や側鎖に各種の官能基を有するものでもよい。上記
の片末端のみにメルカプト基を有するＰＶＡ系重合体
は、例えば、チオール酸の存在下にビニルエステル系単
量体を主体とするビニル単量体を重合して得たポリビニ
ルエステル系重合体を常法によりけん化することによっ
て調製することができる。また、メルカプト基を有する
ＰＶＡにおいて、メルカプト基以外の従来公知のアニオ
ン性、ヤチオン性、非イオン性等の各種の変性基を導入
することができる。In the method for producing an aqueous emulsion of the present invention, a polyvinyl alcohol polymer having a mercapto group is used as the dispersant. As the PVA-based polymer having a mercapto group, a PVA-based polymer having a mercapto group in the main chain of the polymer may be used,
This is preferable because a PVA-based polymer having a mercapto group only at the terminal of a molecular piece is easy to handle because there is no fear of insolubilization, since there is a risk of forming a disulfide bond due to oxidation of PVA itself to make it insoluble. The PVA-based polymer having a terminal mercapto group used in the present invention may have various functional groups in the main chain or side chain of the PVA-based polymer in addition to the terminal mercapto group. The PVA-based polymer having a mercapto group only at one end is, for example, a polyvinyl ester-based polymer obtained by polymerizing a vinyl monomer mainly containing a vinyl ester-based monomer in the presence of thiol acid. It can be prepared by saponification according to a conventional method. In addition, in the PVA having a mercapto group, various conventionally known anionic, yathionic, nonionic and other modifying groups other than the mercapto group can be introduced.
【００１０】本発明において使用される末端にメルカプ
ト基を有するＰＶＡ系重合体の重合度は、各種の状況に
応じて選定すればよく、特に制限はないが、３５００以
下が好ましく、１５００以下がより好ましい。また、け
ん化度は、他の変性基の種類によっても異なり、一義的
には定められないが、水溶性の点からは７０モル％以上
が好ましい。また、この分散剤は、末端にメルカプト基
を有するＰＶＡ系重合体のみから構成することもできる
が、乳化重合安定性等を損なわない範囲で、従来公知の
ＰＶＡ系重合体や、ＰＶＡ系重合体以外の乳化安定剤を
併用することができる。末端にメルカプト基を有するＰ
ＶＡ系重合体は、そのメルカプト基がラジカル反応にお
いて極めて活性なものであるため、メルカプト基を有さ
ない従来のＰＶＡ系重合体を分散剤とした場合には安定
なエマルジョンを得ることが極めて困難であったメタク
リル酸エステル系単量体、アクリル酸エステル系単量
体、スチレン系単量体、ジエン系単量体およびハロゲン
化不飽和単量体などのラジカル反応性の比較的小さい単
量体に対しても、高度に反応することができる。その結
果、末端にメルカプト基を有するＰＶＡ系単量体は、上
記単量体を構成単位とする共重合体からなる分散質の粒
子と化学的に結合して極めて安定な水性エマルジョンを
与えることができる。The degree of polymerization of the PVA polymer having a mercapto group at the terminal used in the present invention may be selected according to various circumstances and is not particularly limited, but is preferably 3500 or less, more preferably 1500 or less. preferable. Further, the saponification degree varies depending on the types of other modifying groups and is not uniquely determined, but it is preferably 70 mol% or more from the viewpoint of water solubility. Further, this dispersant can be composed only of a PVA-based polymer having a mercapto group at the terminal, but within a range that does not impair emulsion polymerization stability or the like, a conventionally known PVA-based polymer or PVA-based polymer is used. Other emulsion stabilizers can be used in combination. P having a mercapto group at the terminal
Since the VA-based polymer has an extremely active mercapto group in a radical reaction, it is extremely difficult to obtain a stable emulsion when a conventional PVA-based polymer having no mercapto group is used as a dispersant. Monomers having relatively small radical reactivity such as methacrylic acid ester-based monomers, acrylic acid ester-based monomers, styrene-based monomers, diene-based monomers and halogenated unsaturated monomers Can also be highly responsive. As a result, the PVA-based monomer having a mercapto group at the terminal may chemically bond with particles of a dispersoid composed of a copolymer having the above-mentioned monomer as a constituent unit to give an extremely stable aqueous emulsion. it can.
【００１１】本発明の水性エマルジョンの製造方法にお
いて、乳化重合の開始剤としては、自己ラジカル発生能
を有さず、メルカプト基を有するＰＶＡ系重合体のメル
カプト基とのレドックス反応によってのみラジカルを発
生させる開始剤であることが必要である。この様な開始
剤としては、臭素酸カリウムが好ましい。また、過硫酸
カリウム、過硫酸アンモニウム、過硫化水素等の他の水
溶性酸化剤でもそれらの熱分解温度以下で自己ラジカル
発生能のない、あるいは非常に小さい温度であれば、使
用可能である。臭素酸カリウムは、通常の重合条件下で
は単独でラジカルを発生せず、メルカプト基を有するＰ
ＶＡ系重合体のメルカプト基とのレドックス反応によっ
てのみ分解し、ＰＶＡ系重合体中にラジカルを発生する
ことから、ＰＶＡが分散質に効率よく化学結合した形で
導入され、安定化効果を大ならしめるので特に好ましい
開始剤である。本発明の水性エマルジョンの製造方法に
おいて、分散剤であるメルカプト基を有するＰＶＡ系重
合体は、乳化重合中に連続的あるいは間欠的に重合系に
添加することが必要である。連続あるいは間欠的に該Ｐ
ＶＡ系重合体を添加しない場合、初期に重合系に一括添
加した該ＰＶＡ系重合体のみでは、メルカプト基が上記
臭素酸カリウム等の開始剤の添加により迅速に消費され
ていくため、比較的低転化率でＤｅａｄ−Ｅｎｄの様相
を呈し、重合を完結させるためには、自己ラジカル発生
能を有する開始剤を追加添加する必要が生じ、その場合
には、重合は完結するものの、化学結合（グラフト）に
よりＰＶＡが分散質に導入される効率が低下し、安定性
や物性を低下させる他、重合のコントロールが困難とな
り、実用的、工業的規模での製造に問題が生じる。一
方、該ＰＶＡ系重合体を連続的あるいは間欠的に重合系
へ添加する場合、重合系のメルカプト基濃度をあるレベ
ル以上に保って重合が進行するため、高転化率まで重合
がスムースに進行し、目的の水性エマルジョンを安定に
しかも実用的かつ工業的規模で製造することができる。
また、本発明の水性エマルジョンの製造方法において、
重合系が酸性であることが望ましい。これは、ラジカル
重合において極めて活性な反応性を示すＰＶＡ系重合体
中のメルカプト基が塩基性下においては、モノマーの二
重結合へイオン的に付加、消失する速度大きく、そのた
め重合効率が著しく低下するためであり、不飽和単量体
の種類にもよるが、全ての重合操作をｐＨ６以下、好ま
しくは、ｐＨ４以下で実施することが望ましい。In the method for producing an aqueous emulsion of the present invention, the emulsion polymerization initiator does not have a self-radical generating ability and generates a radical only by a redox reaction with a mercapto group of a PVA polymer having a mercapto group. It is necessary to be an initiator that makes it possible. As such an initiator, potassium bromate is preferable. Further, other water-soluble oxidizing agents such as potassium persulfate, ammonium persulfate, hydrogen persulfide and the like can be used as long as they have no self-radical generating ability at a temperature below their thermal decomposition temperature or have a very small temperature. Potassium bromate does not generate a radical by itself under ordinary polymerization conditions and has a mercapto group-containing P.
It decomposes only by the redox reaction with the mercapto group of the VA-based polymer and generates a radical in the PVA-based polymer, so that PVA is introduced in a form efficiently chemically bonded to the dispersoid, and if the stabilizing effect is large. It is a particularly preferable initiator since it is used. In the method for producing an aqueous emulsion of the present invention, the PVA-based polymer having a mercapto group, which is a dispersant, needs to be continuously or intermittently added to the polymerization system during emulsion polymerization. The P continuously or intermittently
When the VA-based polymer is not added, the mercapto group is rapidly consumed by the addition of the above-mentioned initiator such as potassium bromate because the PVA-based polymer added to the polymerization system at once is relatively low. In order to show the appearance of Dead-End in the conversion rate and to complete the polymerization, it is necessary to additionally add an initiator having a self-radical generating ability. In that case, although the polymerization is completed, a chemical bond (graft In addition to lowering the efficiency of introducing PVA into the dispersoid, the stability and physical properties are reduced, and it becomes difficult to control the polymerization, which causes problems in practical and industrial scale production. On the other hand, when the PVA-based polymer is continuously or intermittently added to the polymerization system, the polymerization proceeds while maintaining the concentration of the mercapto group in the polymerization system at a certain level or higher, so that the polymerization proceeds smoothly up to a high conversion rate. The target aqueous emulsion can be stably produced on a practical and industrial scale.
Further, in the method for producing an aqueous emulsion of the present invention,
It is desirable that the polymerization system is acidic. This is because the mercapto group in the PVA-based polymer, which exhibits extremely active reactivity in radical polymerization, is ionically added to and disappears from the double bond of the monomer under basic conditions, resulting in a marked decrease in polymerization efficiency. However, it is desirable to carry out all the polymerization operations at pH 6 or less, preferably pH 4 or less, depending on the type of unsaturated monomer.
【００１２】本発明の水性エマルジョンの製造方法にお
いて、上記以外の重合条件あるいは重合方法は特に制限
はなく、各種の従来公知の乳化重合方法を採用すること
ができる。本発明の特徴は、ビニルエステル系単量体は
もちろんのこと、従来ＰＶＡを分散剤とした乳化重合で
は安定性の良好なエマルジョンを得ることが困難であっ
たスチレン−ブタジエン共重合系、メチルメタクリレー
ト−ブタジエン共重合系、（メタ）アクリル酸エステル
等のアクリル系の単独重合または共重合系においても本
発明の水性エマルジョンの製造方法を採用すれば実用
的、工業的規模で安定かつＰＶＡの分散質への乳化結合
（グラフト）率の高い水性エマルジョンが得られること
にある。In the method for producing the aqueous emulsion of the present invention, the polymerization conditions or the polymerization method other than the above are not particularly limited, and various conventionally known emulsion polymerization methods can be adopted. A feature of the present invention is that not only vinyl ester-based monomers but also styrene-butadiene copolymer system, methyl methacrylate, which has been difficult to obtain an emulsion having good stability by emulsion polymerization using PVA as a dispersant. In a homopolymerization or copolymerization system of butadiene copolymerization system, acrylic homopolymer such as (meth) acrylic acid ester, etc., if the method for producing an aqueous emulsion of the present invention is adopted, it is stable on a practical and industrial scale and dispersoid of PVA. It is to obtain an aqueous emulsion having a high rate of emulsion bonding (grafting) to.
【００１３】このようにして得られる水性エマルジョン
は、そのまま、あるいは従来公知の添加剤を添加して、
各種の用途に利用される。例えば、塗料、接着剤、繊維
加工剤、紙加工剤、無機物バインダー、セメント混和
剤、モルタルプライマー等広範な用途に利用される。The aqueous emulsion thus obtained may be used as it is or by adding conventionally known additives,
It is used for various purposes. For example, it is used for a wide range of applications such as paints, adhesives, fiber processing agents, paper processing agents, inorganic binders, cement admixtures and mortar primers.
【００１４】以下、実施例を挙げて本発明を具体的に説
明するが、本発明はこれらによって何等限定されるもの
ではない。なお実施例中、「部」および「％」はいずれ
も重量基準を意味する。Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto. In the examples, "parts" and "%" mean weight basis.
【００１５】実施例１ 還流冷却器、滴下ロート、温度計、窒素吸込口を備えた
ガラス製重合容器に、末端にメルカプト基を有するＰＶ
Ａ（重合度５５０、けん化度８８．３モル％、メルカプ
ト基含量３．５×１０-5当量／ｇ）２．５部とイオン交
換水８０部を加え、９５℃で完全溶解させた。次いで硫
酸でｐＨ＝３．０とした後、メチルメタクリレート１０
部とｎ−ブチルアクリレート１０部を添加し、窒素置換
後６５℃まで昇温し、２％臭素酸カリウム水溶液０．７
部を添加して重合を開始し、さらに２時間かけてメチル
メタクリレート４０部とｎ−ブチルアクリレート４０部
を連続的に添加した。この間、末端にメルカプト基を有
するＰＶＡ（重合度５５０、けん化度８８．３モル％、
メルカプト基含量３．３×１０-5当量／ｇ）の１０％水
溶液２５部および１％臭素酸カリウム水溶液５部を連続
的に重合系に添加した。重合開始３時間後、転化率９
９．５％となり重合を終了した。固形分濃度４９．０
％、粘度３５０ｍｐａｓ．ｓの安定はメチルメタクリレ
ート／ｎ−ブチルアクリレート共重合体エマルジョンを
得た。Example 1 A glass polymerization vessel equipped with a reflux condenser, a dropping funnel, a thermometer, and a nitrogen inlet was used, and PV having a mercapto group at its end was used.
2.5 parts of A (degree of polymerization 550, degree of saponification 88.3 mol%, mercapto group content 3.5 × 10 −5 equivalent / g) and 80 parts ion-exchanged water were added and completely dissolved at 95 ° C. Next, after adjusting the pH to 3.0 with sulfuric acid, methyl methacrylate 10
Parts and 10 parts of n-butyl acrylate were added, the temperature was raised to 65 ° C. after nitrogen substitution, and a 2% potassium bromate aqueous solution 0.7 was added.
Then, 40 parts of methyl methacrylate and 40 parts of n-butyl acrylate were continuously added over 2 hours. During this period, PVA having a mercapto group at the end (polymerization degree 550, saponification degree 88.3 mol%,
25 parts of a 10% aqueous solution having a mercapto group content of 3.3 × 10 −5 equivalent / g) and 5 parts of a 1% potassium bromate aqueous solution were continuously added to the polymerization system. 3 hours after initiation of polymerization, conversion rate 9
Polymerization was completed at 9.5%. Solid content concentration 49.0
%, Viscosity 350 mpas. As for the stability of s, a methyl methacrylate / n-butyl acrylate copolymer emulsion was obtained.
【００１６】・顕微鏡観察 得られたエマルジョンを希釈し、４００倍の位相差顕微
鏡で観察した。Microscopic observation The obtained emulsion was diluted and observed with a phase contrast microscope of 400 times.
【００１７】・ＰＶＡの化学結合（グラフト）率の固定 得られたエマルジョンを減圧下乾燥し、ベンゼン、水で
交互抽出した。これを３サイクルくり返し、残査が恒量
になったことを確認し、残査を常法によりアセチル化
し、ＮＭＲでその組成を求めた（残査中のＰＶＡ含有
率）。以下の式でＰＶＡの化学結合（グラフト率）を算
出した。 化学結合（グラフト）率［％］＝（残査重量×残査中の
ＰＶＡ含有率）／（仕込みＰＶＡ量）Fixing the chemical bonding (grafting) ratio of PVA The obtained emulsion was dried under reduced pressure and alternately extracted with benzene and water. This was repeated for 3 cycles, and it was confirmed that the residual amount became constant, the residual amount was acetylated by a conventional method, and its composition was determined by NMR (PVA content rate in the residual amount). The chemical bond (graft ratio) of PVA was calculated by the following formula. Chemical bond (graft) rate [%] = (residual weight × PVA content in residual) / (amount of PVA charged)
【００１８】比較例１ 実施例１において、末端にメルカプト基を有するＰＶＡ
（重合度５５０、けん化度８８．３モル％、メルカプト
基含量３．３×１０-5当量／ｇ）５部を初期に一括で用
い、重合中に連続添加しないこと以外は、実施例１と同
様にした。その結果、３時間後の転化率が４５．５％で
ありＤｅａｄ−Ｅｎｄとなつた。そこで過硫酸カリウム
０．５部を追加し重合を完結させた。得られた水性エマ
ルジョンは、固形分濃度４９．０％、粘度１８５ｍｐａ
ｓ．ｓであった。実施例１と同様に顕微鏡観察及びＰＶ
Ａの化学結合（グラフト）率を求めた。Comparative Example 1 PVA having a mercapto group at the end in Example 1
Example 1 except that 5 parts (polymerization degree 550, saponification degree 88.3 mol%, mercapto group content 3.3 × 10 −5 equivalent / g) were initially used all at once and were not continuously added during the polymerization. I did the same. As a result, the conversion rate after 3 hours was 45.5%, which was Dead-End. Then, 0.5 part of potassium persulfate was added to complete the polymerization. The obtained aqueous emulsion had a solid content concentration of 49.0% and a viscosity of 185 mpa.
s. It was s. Microscopic observation and PV as in Example 1.
The chemical bond (grafting) rate of A was determined.
【００１９】比較例２ 実施例１において、臭素酸カリウムの代わりに過硫酸カ
リウムを用いる以外は実施例１と同様にした。３時間
後、転化率は９９．６％であったが、ブロックが多量に
発生した。固形分は４８．３％、粘度は９０ｍｐａｓ．
ｓであった。Comparative Example 2 The procedure of Example 1 was repeated, except that potassium persulfate was used instead of potassium bromate. After 3 hours, the conversion was 99.6%, but a large amount of blocks were generated. The solid content is 48.3% and the viscosity is 90 mpas.
It was s.
【００２０】比較例３ 実施例１において、末端にメルカプト基を有するＰＶＡ
の代わりに無変性ＰＶＡ（重合度５５０、けん化度８
８．０モル％）を用い、開始剤として過硫酸カリウムを
用いる以外は実施例１と同様にした。モノマー逐次添加
中に重合系がゲル化した。Comparative Example 3 PVA having a mercapto group at the end in Example 1
Instead of unmodified PVA (polymerization degree 550, saponification degree 8
(8.0 mol%), and potassium persulfate was used as the initiator. The polymerization system gelled during the sequential addition of the monomers.
【００２１】実施例２ 窒素吸込口、温度計を備えた耐圧オートグレーブに、末
端にメルカプト基を有するＰＶＡ（重合度５５０、けん
化度８８．３モル％、メルカプト基含量３．３×１０-5
当量／ｇ）１部と末端にメルカプト基を有するＰＶＡ
（重合度１５００、けん化度８８．１モル％、メルカプ
ト基含量１．３×１０-5当量／ｇ）１部をイオン交換水
８０部に９５℃で完全溶解させた。次いで、硫酸でｐＨ
＝３．８とした後、酢酸ビニル８０部を加え、６０℃に
昇温し、窒素置換を行った後エチレンを４５Ｋｇ／ｃｍ
2まで圧入した。０．５％臭素酸カリウムを３時間かけ
て連続添加して重合を開始し、同時に末端にメルカプト
基を有するＰＶＡ（重合度３００、けん化度８８．０モ
ル％、メルカプト基含量５．４×１０-5当量／ｇ）の１
０％水溶液を３０部を３時間かけて連続添加した。３時
間後、酢酸ビニル濃度が１．０％となり重合を終了し
た。固形分濃度４９．２％、粘度１０５０ｍｐａｓ．ｓ
のエチレン−酢酸ビニル共重合体エマルジョンが得られ
た。このエマルジョンを用いて実施例１と同様に評価し
た。Example 2 A PVA having a mercapto group at its end (polymerization degree 550, saponification degree 88.3 mol%, mercapto group content 3.3 × 10 -5) was used in a pressure resistant auto-grade equipped with a nitrogen inlet and a thermometer.
Equivalent / g) PVA having 1 part and a mercapto group at the end
(Polymerization degree 1500, saponification degree 88.1 mol%, mercapto group content 1.3 × 10 −5 equivalent / g) 1 part was completely dissolved at 95 ° C. in 80 parts ion-exchanged water. Then pH with sulfuric acid
= 3.8, 80 parts of vinyl acetate was added, the temperature was raised to 60 ° C., nitrogen substitution was carried out, and then 45 kg / cm of ethylene.
Pressed up to 2 . Polymerization was initiated by continuously adding 0.5% potassium bromate over 3 hours, and at the same time PVA having a mercapto group at the end (polymerization degree 300, saponification degree 88.0 mol%, mercapto group content 5.4 × 10 5 -5 equivalent / g) 1
30 parts of 0% aqueous solution was continuously added over 3 hours. After 3 hours, the vinyl acetate concentration reached 1.0% and the polymerization was completed. Solid content concentration 49.2%, viscosity 1050 mpas. s
The ethylene-vinyl acetate copolymer emulsion of was obtained. This emulsion was used and evaluated in the same manner as in Example 1.
【００２２】実施例３ 窒素吸込口、温度計を備えた耐圧オートグレーブに、末
端にメルカプト基を有するＰＶＡ（重合度３００、けん
化度９２．０モル％、メルカプト基含量６．５×１０-5
当量／ｇ）の２％水溶液１００部を仕込み、硫酸でｐＨ
＝４．０に調製後、スチレン６０部を仕込んだ。次い
で、ブタジエン４０部を耐圧計量器より圧入して、７０
℃に昇温した後、２％臭素酸カリウム水溶液２５部を圧
入して重合を開始した。また、重合が開始してから末端
にメルカプト基を有するＰＶＡ（重合度３００、けん化
度９２．０モル％、メルカプト基含量６．５×１０-5当
量／ｇ）の１０％水溶液３０部を５時間後、１０時間
後、１５時間後に１０部づつ間欠添加した。内圧は、
４．６Ｋｇ／ｃｍ2から重合の進行と共に低下し、２０
時間後には０．４Ｋｇ／ｃｍ2となり重合率を求めたと
ころ９８．０％であった。固形分濃度４０．５％、粘度
１００ｍｐａｓ．ｓのスチレン−ブタジエン共重合体エ
マルジョンを得た。Example 3 A PVA having a mercapto group at its end (polymerization degree 300, saponification degree 92.0 mol%, mercapto group content 6.5 × 10 -5) was placed in a pressure resistant auto-grade equipped with a nitrogen inlet and a thermometer.
Charge 100 parts of a 2% aqueous solution (equivalent / g) and add sulfuric acid to adjust
After being adjusted to 4.0, 60 parts of styrene was charged. Then, 40 parts of butadiene was press-fitted with a pressure-resistant measuring device to obtain 70
After the temperature was raised to 0 ° C., 25 parts of a 2% potassium bromate aqueous solution was injected under pressure to initiate polymerization. In addition, 30 parts of a 10% aqueous solution of PVA having a mercapto group at the terminal after the initiation of polymerization (polymerization degree 300, saponification degree 92.0 mol%, mercapto group content 6.5 × 10 −5 equivalent / g) was added. After 10 hours, 10 hours, and 15 hours, 10 parts were intermittently added. The internal pressure is
It decreases from 4.6 Kg / cm 2 as the polymerization progresses,
After a lapse of time, it became 0.4 kg / cm 2 and the polymerization rate was determined to be 98.0%. Solid content concentration 40.5%, viscosity 100 mpas. A styrene-butadiene copolymer emulsion of s was obtained.
【００２３】比較例４ 実施例３において、末端にメルカプト基を有するＰＶＡ
を初期一括仕込みとする以外は、実施例３と同様にし
た。７時間後重合率４２％で重合はＤｅａｄ−Ｅｎｄの
様相を呈したため、２％過硫酸カリウム水溶液１０部を
圧入して重合を完結させた。重合率９９．０％、固形分
濃度３９．５％、粘度７５ｍｐａｓ．ｓであった。Comparative Example 4 PVA having a mercapto group at the terminal in Example 3
The same procedure as in Example 3 was performed except that the initial batch charging was performed. After 7 hours at a polymerization rate of 42%, the polymerization had a Dead-End appearance, so 10 parts of a 2% potassium persulfate aqueous solution was press-fitted to complete the polymerization. Polymerization rate 99.0%, solid content concentration 39.5%, viscosity 75 mpas. It was s.
【００２４】上記の実施例および比較例の結果を表１に
示す。The results of the above Examples and Comparative Examples are shown in Table 1.
【００２５】[0025]
【表１】 [Table 1]
【００２６】[0026]
【発明の効果】表１に示したように、本発明の水性エマ
ルジョンの製造法は、メルカプト基を有するＰＶＡの分
散質への化学結合（グラフト）率が高い水性エマルジョ
ンを安定に、かつ、実用的、工業的規模で実施できるも
のであることがわかる。As shown in Table 1, the method for producing an aqueous emulsion of the present invention provides stable and practical use of an aqueous emulsion having a high rate of chemical bonding (grafting) of PVA having a mercapto group to a dispersoid. It can be seen that it can be implemented on an industrial or industrial scale.
Claims (2)
ール系重合体からなる分散剤の存在下で、エチレン性不
飽和単量体およびジエン系単量体から選ばれた一種ある
いは二種以上の単量体を乳化重合するに際し、該ポリビ
ニルアルコール系重合体のメルカプト基とのレドックス
反応によってのみラジカルを発生させる開始剤を用い、
かつ、乳化重合中に該ポリビニルアルコール系重合体を
重合系に連続的あるいは間欠的に添加することを特徴と
する水性エマルジョンの製造方法。1. In the presence of a dispersant comprising a polyvinyl alcohol-based polymer having a mercapto group, one or more monomers selected from an ethylenically unsaturated monomer and a diene-based monomer are added. Upon emulsion polymerization, using an initiator that generates a radical only by a redox reaction with the mercapto group of the polyvinyl alcohol-based polymer,
A method for producing an aqueous emulsion, characterized in that the polyvinyl alcohol polymer is continuously or intermittently added to the polymerization system during emulsion polymerization.
記載の水性エマルジョンの製造方法。2. The initiator is potassium bromate.
A method for producing the aqueous emulsion described.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6930794A JPH07278212A (en) | 1994-04-07 | 1994-04-07 | Production of aqueous emulsion |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6930794A JPH07278212A (en) | 1994-04-07 | 1994-04-07 | Production of aqueous emulsion |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH07278212A true JPH07278212A (en) | 1995-10-24 |
Family
ID=13398781
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6930794A Pending JPH07278212A (en) | 1994-04-07 | 1994-04-07 | Production of aqueous emulsion |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH07278212A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH11335490A (en) * | 1998-05-28 | 1999-12-07 | Nippon Zeon Co Ltd | Aqueous emulsion and its production |
| JP2001151975A (en) * | 1999-11-26 | 2001-06-05 | Nippon Zeon Co Ltd | Binder for nonwoven fabric |
| US8030398B2 (en) | 2003-04-09 | 2011-10-04 | Kuraray Co., Ltd. | Method for producing a (meth)acrylic resin emulsion |
-
1994
- 1994-04-07 JP JP6930794A patent/JPH07278212A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH11335490A (en) * | 1998-05-28 | 1999-12-07 | Nippon Zeon Co Ltd | Aqueous emulsion and its production |
| JP2001151975A (en) * | 1999-11-26 | 2001-06-05 | Nippon Zeon Co Ltd | Binder for nonwoven fabric |
| US8030398B2 (en) | 2003-04-09 | 2011-10-04 | Kuraray Co., Ltd. | Method for producing a (meth)acrylic resin emulsion |
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