JPH0665308A - Production of vinyl polymer particle and expandable vinyl polymer particle - Google Patents

Abstract

PURPOSE:To produce polymer particles which give a molded foam having an improved appearance without detriment to the foaming characteristics of the particles including particle size distribution. CONSTITUTION:Vinyl polymer particles are produced by the suspension polymn. of a polymerizable mixture comprising a vinyl monomer and a polymn. initiator in an aq. medium contg. a hardly sol. phosphate and an anionic surfactant. The polymn. is started after the temp. of the suspension is raised to 80-90 deg.C and continued at 80-90 deg.C until the conversion reaches 40wt.%. Then, the temp. is raised by at least 5 deg.C and the polymn. is continued at 90-100 deg.C until the conversion reaches 95wt.%.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は、品質及び成形性に優れ
るビニル系重合体粒子の製造法および成形品の表面平滑
性に優れる発泡性ビニル系重合体粒子の製造法に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing vinyl polymer particles excellent in quality and moldability and a method for producing expandable vinyl polymer particles excellent in surface smoothness of a molded product.

【０００２】[0002]

【従来の技術】近年、発泡成形品の表面に各種の印刷が
行われることが多くなり、表面平滑性に優れた発泡成形
品が求められるようになってきた。これは発泡成形品の
表面に凹凸があると、凹部分が印刷されず白く残り印刷
外観の見映えが低下するためである。特に発泡性重合体
粒子を使用する発泡ポリスチレンでは発泡粒子間の間隙
が十分に埋まりにくいため、表面平滑性を向上させるこ
とが一層要求される。この発泡ポリスチレン用重合体粒
子を得るために従来からベンゾイルペルオキシドやラウ
ロイルペルオキシド等の過酸化物系開始剤及びアゾビス
イソブチロニトリル等のアゾ化合物系開始剤が使用され
てきた。しかしながらこれらの開始剤を使用した発泡性
重合体粒子では、成形品の表面平滑性に優れた発泡成形
品を得ることが困難であった。2. Description of the Related Art In recent years, various types of printing have been frequently performed on the surface of foam molded articles, and foam molded articles having excellent surface smoothness have been demanded. This is because if the surface of the foamed molded product has irregularities, the concave portions are not printed and remain white, and the appearance of the printed appearance deteriorates. In particular, in expanded polystyrene using expandable polymer particles, it is difficult to sufficiently fill the gaps between expanded particles, and therefore it is further required to improve the surface smoothness. In order to obtain the polymer particles for expanded polystyrene, peroxide type initiators such as benzoyl peroxide and lauroyl peroxide and azo compound type initiators such as azobisisobutyronitrile have been conventionally used. However, with the expandable polymer particles using these initiators, it was difficult to obtain a foamed molded product having excellent surface smoothness of the molded product.

【０００３】特開昭５８−２２２１２１号公報、特開昭
６２−１１７４０号公報、特開昭６１−２１４５４４号
公報、特開昭６３−６９８４４号公報、特開平１−２８
９８４１号公報および特開平１−２９９８４３号公報に
は発泡剤を含浸した発泡ポリスチレン用重合体粒子の表
面に表皮部を侵食する表面添加剤を塗ることにより表層
部に発泡しない層を設け発泡成形品の表面平滑性を向上
させる方法が記載されているが、この方法では発泡成形
品の表面平滑性が向上するものの、発泡剤であるガスが
逸散しやすく、発泡性ポリスチレン重合体粒子の製品と
しての寿命が短くなるという欠点がある。JP-A-58-222121, JP-A-62-11740, JP-A-61-214544, JP-A-63-69844 and JP-A-1-28.
No. 9841 and Japanese Patent Application Laid-Open No. 1-299843 disclose a foam-molded article in which a non-foaming layer is provided on the surface layer by coating the surface of polymer particles for expanded polystyrene impregnated with a foaming agent with a surface additive that corrodes the skin. Although a method for improving the surface smoothness of the foamed product is described, this method improves the surface smoothness of the foamed molded product, but the gas that is the foaming agent easily dissipates as a product of the expandable polystyrene polymer particles. It has the drawback of shortening the life of the.

【０００４】また特開平３−３９３３４号公報には本発
明とは別の目的で重合バッチを最大で数時間８０℃〜９
０℃に迅速加熱して重合開始し、反応温度を毎時８℃〜
１７℃ずつ１２０℃〜１３０℃まで上昇させ、１００℃
に到達した際に交換率は３０％〜６０％で、最高温度に
到達した際に変換率は少なくとも８０％で、バッチを１
００℃〜１３０℃の温度で、重合体中の残留単量体含量
を０．１％未満に減少するまで維持して、パール状の重
合体を得る方法が記載されているが、この方法では反応
時間を減少させることができるが、得られる発泡性重合
体粒子の品質再現性に問題があり、工業上可能な操作範
囲が非常に狭い欠点があり、さらには粒径分布の狭い重
合体粒子が得られない等の問題がある。Further, in JP-A-3-39334, for the purpose other than the present invention, a polymerization batch is subjected to a maximum of several hours at 80 ° C. to 9 ° C.
Polymerization is initiated by rapid heating to 0 ° C, and the reaction temperature is 8 ° C / hr.
100 degrees Celsius, increasing by 17 degrees Celsius from 120 degrees Celsius to 130 degrees Celsius
The exchange rate is 30% to 60% when reaching the maximum temperature, and the conversion rate is at least 80% when the maximum temperature is reached.
A method of obtaining a pearl-like polymer by maintaining the residual monomer content in the polymer at a temperature of 00 ° C to 130 ° C until it is reduced to less than 0.1% is described. Although the reaction time can be reduced, there is a problem in the quality reproducibility of the expandable polymer particles to be obtained, there is a drawback that the industrially operable range is very narrow, and further, the polymer particles having a narrow particle size distribution. There is a problem such as not being able to obtain.

【０００５】[0005]

【発明が解決しようとする課題】発泡成形品の表面平滑
性について種々検討した結果、重合後期の重合温度を上
昇させることにより、上記欠点が解消され、表面平滑性
が向上することを見出し本発明に至った。すなわち本発
明は、ビニル系単量体と重合開始剤とを含む重合性単量
体混合物を難溶性燐酸塩と陰イオン界面活性剤とを加え
た水性媒体中で懸濁重合するのに際し、重合開始から重
合転化率が４０重量％未満までの重合温度を８０℃〜９
０℃の範囲の温度とし、重合転化率が４０重量％〜９５
重量％の間で重合温度を少なくとも５℃以上上げて９０
℃〜１００℃の範囲の温度とすることを特徴とするビニ
ル系重合体粒子の製造法に関する。また、本発明は、該
ビニル系重合体粒子の製造法において重合途中又は重合
後、発泡剤を含浸させることを特徴とする発泡性ビニル
系重合体粒子の製造法に関する。As a result of various studies on the surface smoothness of the foamed molded product, it was found that the above-mentioned drawbacks are eliminated and the surface smoothness is improved by increasing the polymerization temperature in the latter stage of the polymerization. Came to. That is, the present invention provides a method for suspension polymerization of a polymerizable monomer mixture containing a vinyl monomer and a polymerization initiator in an aqueous medium containing a sparingly soluble phosphate and an anionic surfactant. The polymerization temperature from the start to the polymerization conversion rate of less than 40% by weight is 80 ° C to 9 ° C.
The temperature is in the range of 0 ° C., and the polymerization conversion rate is 40% by weight to 95%.
Increase the polymerization temperature by at least 5 ° C or more between 90% by weight and 90%.
The present invention relates to a method for producing vinyl polymer particles, characterized in that the temperature is in the range of 100 to 100 ° C. The present invention also relates to a method for producing expandable vinyl polymer particles, which comprises impregnating a foaming agent during or after polymerization in the method for producing vinyl polymer particles.

【０００６】本発明は、懸濁安定化剤として難溶性燐酸
塩及び陰イオン界面活性剤を含む水性媒体に、ビニル系
単量体及びビニル系単量体に可溶な重合開始剤を含有す
る重合性単量体混合物を添加して懸濁重合を開始し、重
合後期の重合温度を上昇させることにより発泡性重合体
粒子の粒径分布や発泡特性を悪化させることなく、優れ
た成形品の表面平滑性を与える発泡性ビニル系重合体粒
子を提供するものである。本発明の重合条件を満たすこ
とができなければ重合体粒子の粒径分布や発泡特性が良
好でも、外観の優れた成形品を得ることができない。According to the present invention, a vinyl monomer and a polymerization initiator soluble in a vinyl monomer are contained in an aqueous medium containing a sparingly soluble phosphate and an anionic surfactant as a suspension stabilizer. Suspension polymerization is started by adding the polymerizable monomer mixture, and the particle size distribution and foaming characteristics of the expandable polymer particles are not deteriorated by increasing the polymerization temperature in the latter stage of the polymerization, and an excellent molded product is obtained. The present invention provides expandable vinyl polymer particles that provide surface smoothness. If the polymerization conditions of the present invention cannot be satisfied, a molded product having an excellent appearance cannot be obtained even if the particle size distribution of the polymer particles and the foaming property are good.

【０００７】一般にビーズを用いた発泡成形品は、懸濁
重合により重合したビニル系重合体粒子に発泡剤を含浸
させた後、この発泡性ビニル系重合体粒子をスチーム等
で予備発泡させ、次いで予備発泡粒子を金型に充填し、
これをスチーム等で再び発泡させて製造される。この様
にして得られる発泡成形品の表面平滑性は予備発泡粒子
の性状に強く依存する。この発泡成形品の表面平滑性に
ついて種々検討した結果、表面平滑性は意外にも重合後
期の重合温度により大きく影響されることを見出した。
すなわち重合後期の重合温度を上昇させると、発泡性ビ
ニル系重合体粒子を予備発泡させたときに、発泡粒子表
面のセル（気泡）の膜厚が内部のセルの膜厚より増大
し、このためにスチーム成形時のスチームに対する耐熱
性が増加し、表面平滑性が向上するという知見を見出し
た。従来の様に重合初期から重合終了まで一定温度で重
合した発泡性ビニル系重合体粒子から得られる予備発泡
粒子は表面のセルの膜厚と内部セルの膜厚がほぼ同じ厚
みか表面のセルの膜厚のほうが薄く、発泡成形後の成形
品の表面平滑性に劣る結果となる。本発明の方法は重量
転化率が４０重量％以降に重合温度を少なくとも５℃以
上上昇させることで予備発泡粒子のセル構造を耐熱性に
優れる構造に変化させることができる。Generally, a foamed molded article using beads is obtained by impregnating vinyl polymer particles polymerized by suspension polymerization with a foaming agent, pre-foaming the expandable vinyl polymer particles with steam or the like, and then Fill the mold with pre-expanded particles,
It is manufactured by foaming this again with steam or the like. The surface smoothness of the foam-molded article thus obtained strongly depends on the properties of the pre-expanded particles. As a result of various studies on the surface smoothness of the foamed molded product, it was found that the surface smoothness is surprisingly greatly influenced by the polymerization temperature in the latter stage of the polymerization.
That is, when the polymerization temperature in the latter half of the polymerization is increased, when the expandable vinyl polymer particles are pre-expanded, the film thickness of the cells (air bubbles) on the surface of the expanded particles becomes larger than the film thickness of the internal cells, It was found that the heat resistance to steam during steam forming was increased and the surface smoothness was improved. The pre-expanded particles obtained from the expandable vinyl polymer particles polymerized at a constant temperature from the beginning to the end of the polymerization as in the conventional case have the same thickness of the surface cell and the inner cell or the surface cell Since the film thickness is thinner, the surface smoothness of the molded product after foam molding is poor. In the method of the present invention, the cell structure of the pre-expanded particles can be changed to a structure having excellent heat resistance by increasing the polymerization temperature by at least 5 ° C. or more after the weight conversion of 40% by weight or more.

【０００８】本発明では重合性単量体と重合開始剤の水
性媒体懸濁液をまず８０℃〜９０℃の温度に昇温して重
合を開始するとともに少なくとも重合転化率が４０重量
％未満の重合温度は８０℃〜９０℃の温度とする（な
お、当然８０℃〜９０℃への昇温の間にもある程度重合
は進行する）。好ましい重合温度は８３℃〜８６℃であ
る。昇温して重合を開始してから重合転化率が４０重量
％未満の重合温度は製造工程の管理及び品質の安定化の
面から一定であることが好ましい。この範囲の重合温度
が９０℃を超える場合には本発明の効果は得られず、ま
た過酸化物系重合開始剤の種類によっては粒径分布が幅
広くなる問題点がある。特にｔ−ブチルペルオキシ−２
−エチルヘキサノエートを開始剤として使用した場合に
は得られる重合体粒子の粒径分布が幅広くなる問題点が
ある。この範囲の重合温度が８０℃未満では重合時間が
著しく長くなるとともに重合体粒子の粒径分布が幅広く
なる。重合温度である８０℃〜９０℃までの昇温速度は
０．５℃／分〜２℃／分とするのが好ましい。昇温速度
がこれより遅いと合成時間が長くなり、一方これより速
いと重合温度のコントロールが難しくなる。このような
昇温速度に従えば、重合転化率が５重量％以下の間に昇
温を完了することができる。In the present invention, an aqueous medium suspension of a polymerizable monomer and a polymerization initiator is first heated to a temperature of 80 ° C. to 90 ° C. to initiate polymerization, and at least the polymerization conversion rate is less than 40% by weight. The polymerization temperature is set to a temperature of 80 ° C to 90 ° C (note that, of course, the polymerization proceeds to some extent during the temperature increase to 80 ° C to 90 ° C). The preferred polymerization temperature is 83 ° C to 86 ° C. It is preferable that the polymerization temperature at which the polymerization conversion rate is less than 40% by weight after the temperature is raised to start the polymerization is constant from the viewpoint of controlling the production process and stabilizing the quality. If the polymerization temperature in this range exceeds 90 ° C., the effect of the present invention cannot be obtained, and there is a problem that the particle size distribution becomes broad depending on the kind of the peroxide type polymerization initiator. Especially t-butylperoxy-2
-When ethylhexanoate is used as an initiator, there is a problem that the particle size distribution of polymer particles obtained is broad. When the polymerization temperature in this range is less than 80 ° C., the polymerization time becomes extremely long and the particle size distribution of the polymer particles becomes broad. The rate of temperature increase from the polymerization temperature of 80 ° C to 90 ° C is preferably 0.5 ° C / min to 2 ° C / min. If the heating rate is slower than this, the synthesis time will be long, while if it is faster, it will be difficult to control the polymerization temperature. According to such a heating rate, the heating can be completed while the polymerization conversion rate is 5% by weight or less.

【０００９】重合転化率が４０重量％〜９５重量％の間
では、重合温度は少なくとも５℃以上上げて９０℃〜１
００℃にすることが必要である。好ましくは８℃以上で
ある。具体的には重合温度を９３℃から９７℃にするこ
とが好ましい。重合転化率が４０重量％以上〜９５重量
％の間での重合温度の上昇が５℃未満の場合には予備発
泡粒子のセル構造を耐熱性に優れる構造に変化させるこ
とができない。重合転化率が４０重量％〜９５重量％の
間で上昇させた重合温度が９０℃未満では本発明の効果
が得られず、また重合転化率が４０重量％〜９５重量％
の間で上昇させた重合温度が１００℃を超えると懸濁系
が不安定化し、巨大粒子の生成や重合装置への重合物の
付着が増加する問題点を生じる。重合温度を５℃以上上
げる時期は重合転化率が４０重量％以降、好ましくは重
合転化率が５０重量％〜７０重量％、特に好ましくは重
合転化率が５０重量％から６５重量％の間である。重合
転化率が４０重量％未満では本発明の効果が得られなく
なるだけでなく、得られる重合体粒子の粒径分布が幅広
くなる問題が生じる。重合温度は必ずしも一度に上げる
必要はなく、段階的に上昇させても連続的に上昇させて
も良い。最終的に５℃以上の差があれば本発明の効果を
得ることができる。例えば３０分以内に１０℃以上上昇
させても良いし、２時間を要して５℃ずつ２段階に上げ
ても良い。昇温速度は特に制限されないが、０．２℃／
分〜１℃／分が好ましい。When the polymerization conversion rate is between 40% by weight and 95% by weight, the polymerization temperature is increased by at least 5 ° C. to 90 ° C.-1.
It is necessary to set the temperature to 00 ° C. It is preferably 8 ° C. or higher. Specifically, the polymerization temperature is preferably 93 ° C to 97 ° C. If the increase in the polymerization temperature is less than 5 ° C when the polymerization conversion rate is between 40% by weight and 95% by weight, the cell structure of the pre-expanded particles cannot be changed to a structure having excellent heat resistance. The effect of the present invention is not obtained at a polymerization temperature of less than 90 ° C., which is increased between 40% by weight and 95% by weight, and the polymerization conversion is 40% by weight to 95% by weight.
If the polymerization temperature increased between 100 ° C. exceeds 100 ° C., the suspension system becomes unstable, resulting in problems such as formation of giant particles and increased adhesion of the polymer to the polymerization apparatus. When the polymerization temperature is increased by 5 ° C. or more, the polymerization conversion rate is 40% by weight or more, preferably the polymerization conversion rate is 50% by weight to 70% by weight, and particularly preferably the polymerization conversion rate is between 50% by weight and 65% by weight. . If the polymerization conversion rate is less than 40% by weight, not only the effect of the present invention cannot be obtained, but also the particle size distribution of the obtained polymer particles becomes wide. The polymerization temperature does not necessarily have to be increased at once, and may be increased stepwise or continuously. Finally, if there is a difference of 5 ° C. or more, the effect of the present invention can be obtained. For example, the temperature may be raised by 10 ° C. or higher within 30 minutes, or may be raised by 5 ° C. in two steps in 2 hours. The heating rate is not particularly limited, but is 0.2 ° C /
Minutes to 1 ° C./minute is preferred.

【００１０】ビニル系単量体に可溶な重合開始剤として
は、半減期が１０時間となる温度（以下１０時間半減期
温度とする）が６５℃〜８０℃である重合開始剤が好ま
しい。さらには、１０時間半減期温度が７０℃〜７５℃
である重合開始剤が好ましい。重合開始剤としてはベン
ゾイルペルオキシド、ｔ−ブチルペルオキシ−２エチル
ヘキサノエート、メチルベンゾイルペルオキシド等の従
来の有機過酸化物系重合開始剤を使用することができる
が、過酸ジアシル系重合開始剤よりも過酸エステル系重
合開始剤のほうが本発明の効果をより顕著に得られるの
で好ましい。１０時間半減期温度がこの範囲以外の重合
開始剤では本発明の温度条件で粒径が揃い、表面平滑性
の優れる重合体粒子を得ることが困難になる。重合開始
剤はビニル系単量体全量に対して、一般に０．０５重量
％〜１重量％の範囲で使用される。好ましくは０．２０
重量％〜０．３５重量％である。重合開始剤は組合せて
使用することも可能である。一般に、発泡性ポリスチレ
ン重合体粒子を合成する場合は本発明に記載されるよう
な重合開始剤が使用されるが、ポリスチレン重合体粒子
中の残存単量体を減少させるためにより高温で分解する
重合開始剤も併用される。例えばｔ−ブチルペルオキシ
ベンゾエートやｔ−ブチルペルオキシイソプロピルカー
ボネートなどを併用することができる。As the polymerization initiator soluble in the vinyl monomer, a polymerization initiator having a half-life temperature of 10 hours (hereinafter referred to as 10-hour half-life temperature) of 65 ° C. to 80 ° C. is preferable. Furthermore, the 10-hour half-life temperature is 70 ° C to 75 ° C.
Are preferred. As the polymerization initiator, a conventional organic peroxide-based polymerization initiator such as benzoyl peroxide, t-butylperoxy-2ethylhexanoate or methylbenzoyl peroxide can be used. Also, a peracid ester-based polymerization initiator is preferable because the effect of the present invention can be more remarkably obtained. With a polymerization initiator having a 10-hour half-life temperature outside this range, the particle size is uniform under the temperature conditions of the present invention, and it becomes difficult to obtain polymer particles with excellent surface smoothness. The polymerization initiator is generally used in the range of 0.05% by weight to 1% by weight based on the total amount of the vinyl-based monomer. Preferably 0.20
% By weight to 0.35% by weight. The polymerization initiators can be used in combination. Generally, when synthesizing expandable polystyrene polymer particles, a polymerization initiator as described in the present invention is used, but a polymerization that decomposes at a higher temperature in order to reduce residual monomers in the polystyrene polymer particles. An initiator is also used together. For example, t-butylperoxybenzoate or t-butylperoxyisopropyl carbonate can be used in combination.

【００１１】懸濁重合に使用する難溶性燐酸塩としては
リン酸三カルシウム、ヒドロキシアパタイト、リン酸マ
グネシウム、リン酸バリウム、リン酸ストロンチウム、
リン酸アルミニウム、リン酸鉄、リン酸コバルト、ピロ
リン酸カルシウム等を使用することができるが、リン酸
三カルシウム、ヒドロキシアパタイトが一般的に使用さ
れる。添加量は重合性単量体の全量に対して０．１重量
％〜０．８重量％が好ましく、特に０．１５重量％〜
０．４重量％が好ましい。As the sparingly soluble phosphate used in suspension polymerization, tricalcium phosphate, hydroxyapatite, magnesium phosphate, barium phosphate, strontium phosphate,
Aluminum phosphate, iron phosphate, cobalt phosphate, calcium pyrophosphate and the like can be used, but tricalcium phosphate and hydroxyapatite are generally used. The addition amount is preferably 0.1% by weight to 0.8% by weight, particularly 0.15% by weight to the total amount of the polymerizable monomer.
0.4% by weight is preferred.

【００１２】陰イオン界面活性剤としては、ドデシルベ
ンゼンスルホン酸ナトリウム、スチレンスルホン酸ナト
リウム、ドデシルスルホン酸ナトリウム、ヂオクチルス
ルホコハク酸ナトリウム等を使用することができる。添
加量は重合性単量体の全量に対して０．０００１重量％
〜０．０１重量％が好ましい。水性媒体としては、主に
水が使用される。水性媒体中に公知の可溶性の無機塩、
例えば塩化ナトリウム、硫酸ナトリウム、硝酸ナリトウ
ム等が含まれていても良い。これらの可溶性の無機塩は
重合体粒子の粒径分布を狭くする効果がある。As the anionic surfactant, sodium dodecylbenzene sulfonate, sodium styrene sulfonate, sodium dodecyl sulfonate, sodium dioctyl sulfosuccinate and the like can be used. The amount added is 0.0001% by weight based on the total amount of the polymerizable monomer.
~ 0.01 wt% is preferred. Water is mainly used as the aqueous medium. Known soluble inorganic salts in aqueous medium,
For example, sodium chloride, sodium sulfate, sodium nitrate, etc. may be contained. These soluble inorganic salts have the effect of narrowing the particle size distribution of polymer particles.

【００１３】ビニル系単量体としては、スチレン、α−
メチルスチレン、クロルスチレン、ビニルトルエン等の
スチレン及びその誘導体、アクリロニトリル、ビニルピ
ロリドン、ビニルピリジン、ビニルカルバゾール、ボリ
ブタジエン、炭素数１〜８のアルコールとアクリル酸ま
たはメタクリル酸のエステルなどを用いることができる
が、発泡性ビニル系重合体粒子とする際は、スチレンま
たはスチレン誘導体を５０重量％以上使用するのが好ま
しい。Vinyl-based monomers include styrene and α-
Styrene and its derivatives such as methylstyrene, chlorostyrene, and vinyltoluene, acrylonitrile, vinylpyrrolidone, vinylpyridine, vinylcarbazole, polybutadiene, esters of alcohol having 1 to 8 carbon atoms and acrylic acid or methacrylic acid, and the like can be used. However, when forming the expandable vinyl polymer particles, it is preferable to use 50% by weight or more of styrene or a styrene derivative.

【００１４】最初に添加される単量体混合物は、ビニル
系単量体と重合開始剤の他に、気泡形成剤として公知の
エチレン酢ビ共重合体、エチレンビスステアリルアミ
ド、メチレンビスステアリルアミド等を含んでいてもよ
い。さらにはジオクチルアジペート、ジオクチルフタレ
ート等の可塑剤を含んでいても良い。The monomer mixture added first is, in addition to the vinyl-based monomer and the polymerization initiator, ethylene vinyl acetate copolymer known as a cell-forming agent, ethylenebisstearylamide, methylenebisstearylamide, etc. May be included. Further, a plasticizer such as dioctyl adipate or dioctyl phthalate may be included.

【００１５】全ビニル系単量体と水性媒体との重量比は
０．８／１〜１．２／１（前者／後者）が好ましい。得
られるビニル系重合体粒子を発泡性ビニル系重合体粒子
とするには、プロパン、ブタン、ペンタン、ヘキサン、
シクロペンタン、シクロヘキサン等の炭化水素、メチレ
ンクロリド、ジクロルジフルオロメタン、トリフルオロ
メタン等のハロゲン炭化水素またはこれらの混合物など
の発泡剤を重合途中または重合後に公知の方法で含浸さ
せることにより得ることができる。この方法によれば平
滑な表面を有する外観の優れた成形品を与える発泡性ビ
ニル系重合体粒子を得ることができる。なお本発明では
重合転化率は重合途中の油滴から比重法により求めた。The weight ratio of all vinyl monomers to the aqueous medium is preferably 0.8 / 1 to 1.2 / 1 (former / latter). The resulting vinyl-based polymer particles can be made into expandable vinyl-based polymer particles by using propane, butane, pentane, hexane,
It can be obtained by impregnating a blowing agent such as a hydrocarbon such as cyclopentane or cyclohexane, a halogen hydrocarbon such as methylene chloride, dichlorodifluoromethane or trifluoromethane, or a mixture thereof by a known method during or after the polymerization. . According to this method, it is possible to obtain expandable vinyl polymer particles which give a molded article having a smooth surface and excellent appearance. In the present invention, the polymerization conversion rate was obtained from the oil droplets during the polymerization by the specific gravity method.

【００１６】[0016]

【実施例】以下、本発明を実施例により説明する。な
お、成形品の表面平滑性の尺度を次の方法で求めて表面
平滑性の良否を判定した。すなわち成形品表面の凹凸
（発泡粒子間の間隙）を非接触方式の表面粗さ計で測定
し、陥没深さの大きいものほど、表面平滑性が悪いと判
定した。また重合体粒子の粒径分布と平均粒径は、それ
ぞれ偏差係数Ｃｖとメディアン径で示す。すなわち累積
重量分布曲線を基にして累積重量が１５％、５０％、８
５％となる粒径をそれぞれｄ₁₅、ｄ₅₀、ｄ₈₅とし偏差係
数ＣｖをＣｖ＝（ｄ₈₅−ｄ₁₅）／ｄ₅₀の式で求め、粒径
分布の広狭を判断した。Ｃｖ値が大きい程粒径分布は広
く、小さい程粒径分布は狭くなる。平均粒径は前述のｄ
₅₀で代表されるメディアン径を採用した。EXAMPLES The present invention will be described below with reference to examples. The surface smoothness of the molded product was determined by the following method to determine the quality of the surface smoothness. That is, the irregularities (the gaps between the foamed particles) on the surface of the molded product were measured by a non-contact type surface roughness meter, and the larger the depression depth, the worse the surface smoothness. The particle size distribution and average particle size of the polymer particles are indicated by the deviation coefficient Cv and the median diameter, respectively. That is, based on the cumulative weight distribution curve, the cumulative weight is 15%, 50%, 8
The deviation coefficient Cv was determined by the equation of Cv = (d ₈₅ −d ₁₅ ) / d ₅₀ , where the particle diameters of 5% were d ₁₅ , d ₅₀ , and d ₈₅ , respectively, and the breadth of the particle diameter distribution was judged. The larger the Cv value, the wider the particle size distribution, and the smaller the Cv value, the narrower the particle size distribution. The average particle size is the above d
_The median diameter represented by ₅₀ was adopted.

【００１７】実施例１ ４ｌオートクレーブに１０重量％リン酸三カルシウム分
散液（日本化学工業（株）製、商品名スーパータイト１
０）２４ｇ、ドデシルベンゼンスルホン酸ナトリウム
（和光純薬工業（株）製）０．０４８ｇ、１０重量％硫
酸ナトリウム（和光純薬工業（株）製）５ｇ、イオン交
換水１１７６ｇを入れてよく撹拌し均一な混合溶液とし
た。次いでｔ−ブチルペルオキシ−２−エチルヘキサノ
エート（日本油脂製、商品名パ−ブチルＯ）３．２ｇ
（０．２８重量％）、ｔ−ブチルペルオキシ−イソプロ
ピルカーボネート（日本油脂（株）製、商品名パーブチ
ルＩ）０．４０ｇ、及びエチレン酢ビ共重合体（日本合
成（株）製、商品名ソアレックスＣＨ）１．２ｇを溶解
したスチレン（電気化学工業（株）製）１１５０ｇを撹
拌しながら添加し、１℃／分の昇温速度で８６℃に昇温
して重合を開始した。重合転化率が４０重量％に達した
時点で１０％リン酸三カルシウム分散液１２ｇを加え、
４０分後（重合転化率５２重量％）に２０分かけて９６
℃に昇温して重合を進めた。重合転化率が９５重量％に
達した時点でさらに１０重量％リン酸三カルシウム分散
液３５ｇを加えた後、シクロヘキサン１１ｇとブタン５
０ｇとを１時間要して導入した。その後１２０℃に２時
間を要して昇温し、１２０℃に５時間保った後、室温ま
で冷却して目的とする発泡性ポリスチレン重合体粒子を
得た。得られた発泡性ポリスチレン重合体粒子の平均径
ｄ₅₀は０．９１mmで偏差係数Ｃｖ値は０．４０であっ
た。得られた発泡性重合体粒子を５５ml/gに予備発泡し
た。予備発泡粒子の表皮部のセル膜厚は２．２μｍで内
部のセル膜厚は１．０μｍであった。予備発泡粒子を２
４時間熟成し、０．０７８ＭＰａのスチーム圧で５秒間
加熱成形を行った。得られた成形品表面の最大陥没深さ
は７７μｍであった。なお、セル膜厚は、予備発泡粒子
をカミソリで切断し、その断面のＳＥＭ写真（×１００
０）から任意に選んだ１０ヵ所のセル膜厚を測定し、そ
の平均値より求めた。Example 1 10 wt% tricalcium phosphate dispersion liquid in a 4 l autoclave (manufactured by Nippon Kagaku Kogyo KK, trade name Super Tight 1)
0) 24 g, sodium dodecylbenzene sulfonate (manufactured by Wako Pure Chemical Industries, Ltd.) 0.048 g, 10 wt% sodium sulfate (manufactured by Wako Pure Chemical Industries, Ltd.) 5 g, and ion-exchanged water 1176 g were added and well stirred. A homogeneous mixed solution was obtained. Next, 3.2 g of t-butylperoxy-2-ethylhexanoate (manufactured by NOF Corporation, trade name perbutyl O)
(0.28% by weight), t-butylperoxy-isopropyl carbonate (Nippon Oil & Fats Co., Ltd., trade name Perbutyl I) 0.40 g, and ethylene vinyl acetate copolymer (Nippon Gosei Co., Ltd., trade name So 1150 g of styrene (manufactured by Denki Kagaku Kogyo Co., Ltd.) in which 1.2 g of Alex CH) was dissolved was added with stirring, and the temperature was raised to 86 ° C. at a heating rate of 1 ° C./min to initiate polymerization. When the polymerization conversion rate reached 40% by weight, 12 g of 10% tricalcium phosphate dispersion was added,
After 40 minutes (polymerization conversion of 52% by weight), 96 minutes over 20 minutes
The temperature was raised to ℃ and the polymerization proceeded. When the polymerization conversion rate reached 95% by weight, 35 g of a 10% by weight tricalcium phosphate dispersion was added, and then 11 g of cyclohexane and 5 parts of butane were added.
0 g was introduced in 1 hour. Thereafter, the temperature was raised to 120 ° C. over 2 hours, the temperature was maintained at 120 ° C. for 5 hours, and then cooled to room temperature to obtain the target expandable polystyrene polymer particles. The expandable polystyrene polymer particles obtained had an average diameter d ₅₀ of 0.91 mm and a deviation coefficient Cv value of 0.40. The expandable polymer particles obtained were pre-expanded to 55 ml / g. The cell thickness of the skin portion of the pre-expanded particles was 2.2 μm, and the cell thickness inside was 1.0 μm. 2 pre-expanded particles
It was aged for 4 hours, and heat-molded at a steam pressure of 0.078 MPa for 5 seconds. The maximum depression depth of the surface of the obtained molded product was 77 μm. The cell film thickness was determined by cutting the pre-expanded particles with a razor and observing a cross-section SEM photograph (× 100).
The cell film thickness was measured at 10 locations arbitrarily selected from 0) and calculated from the average value.

【００１８】実施例２ 実施例１において重合途中（重合転化率４０重量％で１
０重量％リン酸三カルシウムを添加した４０分後）で９
３℃に昇温した以外は実施例１と同様に懸濁重合を行
い、発泡性重合体粒子を得た。得られた発泡性ポリスチ
レン重合体粒子の平均径ｄ₅₀は０．９２mmで偏差係数Ｃ
ｖ値は０．４１であった。得られた発泡性重合体粒子を
５５ml/gに予備発泡した。予備発泡粒子の表皮部のセル
膜厚は１．８μｍで内部のセル膜厚は１．１μｍであっ
た。予備発泡粒子を２４時間熟成し、実施例１と同様の
成形条件を行った。得られた成形品表面の最大陥没深さ
は８０μｍであった。Example 2 In the process of Example 1, during the polymerization (at a polymerization conversion rate of 40% by weight, 1
40 minutes after adding 0 wt% tricalcium phosphate) 9
Suspension polymerization was performed in the same manner as in Example 1 except that the temperature was raised to 3 ° C. to obtain expandable polymer particles. The expandable polystyrene polymer particles thus obtained had an average diameter d ₅₀ of 0.92 mm and a deviation coefficient C.
The v value was 0.41. The expandable polymer particles obtained were pre-expanded to 55 ml / g. The cell thickness of the skin portion of the pre-expanded particles was 1.8 μm, and the cell thickness inside was 1.1 μm. The pre-expanded particles were aged for 24 hours and subjected to the same molding conditions as in Example 1. The maximum depression depth of the surface of the obtained molded product was 80 μm.

【００１９】比較例１ 実施例１において重合途中で（実施例２と同じ時期）で
昇温を行わなかった以外は実施例１と同様に懸濁重合を
行い、発泡性重合体粒子を得た。得られた発泡性ポリス
チレン重合体粒子の平均径ｄ₅₀は０．９３mmで偏差係数
Ｃｖ値を０．４０であった。得られた発泡性重合体粒子
を５５ml/gに予備発泡した。予備発泡粒子の表皮部のセ
ル膜厚は０．９μｍで内部のセル膜厚は１．４μｍであ
った。予備発泡粒子を２４時間熟成し、実施例１と同様
の成形条件で成形を行った。得られた成形品表面の最大
陥没深さは９０μｍであった。Comparative Example 1 Foamable polymer particles were obtained by carrying out suspension polymerization in the same manner as in Example 1 except that the temperature was not raised during the polymerization (at the same time as in Example 2). . The expandable polystyrene polymer particles thus obtained had an average diameter d ₅₀ of 0.93 mm and a deviation coefficient Cv value of 0.40. The expandable polymer particles obtained were pre-expanded to 55 ml / g. The cell thickness of the skin portion of the pre-expanded particles was 0.9 μm, and the cell thickness inside was 1.4 μm. The pre-expanded particles were aged for 24 hours and molded under the same molding conditions as in Example 1. The maximum depth of depression on the surface of the obtained molded product was 90 μm.

【００２０】比較例２ 実施例１において重合途中（実施例２と同じ時期）で９
０℃に昇温した以外は実施例２と同様に懸濁重合を行
い、発泡性重合体粒子を得た。得られた発泡性ポリスチ
レン重合体粒子の平均径ｄ₅₀は０．９２mmで偏差係数Ｃ
ｖ値は０．４１であった。得られた発泡性重合体粒子を
５５ml/gに予備発泡した。予備発泡粒子の表皮部のセル
膜厚は１．１μｍで内部のセル膜厚は１．２μｍであっ
た。予備発泡粒子を２４時間熟成し、実施例１と同様の
成形条件で成形を行った。得られた成形品表面の最大陥
没深さは８８μｍであった。Comparative Example 2 In Example 1, during polymerization (at the same time as Example 2), 9
Suspension polymerization was performed in the same manner as in Example 2 except that the temperature was raised to 0 ° C. to obtain expandable polymer particles. The expandable polystyrene polymer particles thus obtained had an average diameter d ₅₀ of 0.92 mm and a deviation coefficient C.
The v value was 0.41. The expandable polymer particles obtained were pre-expanded to 55 ml / g. The cell thickness of the skin portion of the pre-expanded particles was 1.1 μm, and the cell thickness inside was 1.2 μm. The pre-expanded particles were aged for 24 hours and molded under the same molding conditions as in Example 1. The maximum depression depth on the surface of the obtained molded product was 88 μm.

【００２１】比較例３ 実施例１において重合初期の重合温度を９１℃とした以
外は実施例１と同様に懸濁重合を行い、発泡性重合体粒
子を得たが、粒径分布が広くなった。得られた発泡性ポ
リスチレン重合体粒子の平均径ｄ₅₀は０．９２mmで偏差
係数Ｃｖ値は０．５５であった。得られた発泡性重合体
粒子を５５ml/gに予備発泡した。予備発泡粒子の表皮部
のセル膜厚は１．３μｍで内部のセル膜厚は１．２μｍ
であった。予備発泡粒子を２４時間熟成し、実施例１と
同様の成形条件で成形を行った。得られた成形品表面の
最大陥没深さは８５μｍであった。Comparative Example 3 Foaming polymer particles were obtained by carrying out suspension polymerization in the same manner as in Example 1 except that the polymerization temperature in the initial stage of polymerization was 91 ° C., but the particle size distribution was widened. It was The expandable polystyrene polymer particles obtained had an average diameter d ₅₀ of 0.92 mm and a deviation coefficient Cv value of 0.55. The expandable polymer particles obtained were pre-expanded to 55 ml / g. The cell thickness of the skin portion of the pre-expanded particles is 1.3 μm and the cell thickness inside is 1.2 μm.
Met. The pre-expanded particles were aged for 24 hours and molded under the same molding conditions as in Example 1. The maximum depression depth on the surface of the obtained molded product was 85 μm.

【００２２】比較例４ 実施例１において重合転化率３０重量％で重合温度を８
６℃から９２℃に昇温した以外は実施例１と同様に懸濁
重合を行い、発泡性重合体粒子を得たが、粒径分布が広
くなった。得られた発泡性ポリエスチレン重合体粒子の
平均径ｄ₅₀は０．９４mmで偏差係数Ｃｖ値は０．４７で
あった。得られた発泡性重合体粒子を５５ml/gに予備発
泡した。予備発泡粒子の表皮部のセル膜厚は１．４μｍ
で内部のセル膜厚は１．２μｍであった。予備発泡粒子
を２４時間熟成し、実施例１と同様の成形条件で成形を
行った。得られた成形品表面の最大陥没深さは８６μｍ
であった。Comparative Example 4 In Example 1, the polymerization conversion was 30% by weight and the polymerization temperature was 8%.
Suspension polymerization was carried out in the same manner as in Example 1 except that the temperature was raised from 6 ° C to 92 ° C to obtain expandable polymer particles, but the particle size distribution was widened. The resulting expandable polystyrene polymer particles had an average diameter d ₅₀ of 0.94 mm and a deviation coefficient Cv value of 0.47. The expandable polymer particles obtained were pre-expanded to 55 ml / g. The cell thickness of the skin of the pre-expanded particles is 1.4 μm
The inner cell film thickness was 1.2 μm. The pre-expanded particles were aged for 24 hours and molded under the same molding conditions as in Example 1. The maximum depression depth of the obtained molded product surface is 86 μm.
Met.

【００２３】実施例３ 実施例１において重合転化率７０重量％で重合温度を８
６℃から９３℃に昇温した以外は実施例１と同様に懸濁
重合を行い、発泡性重合体粒子を得た。得られた発泡性
ポリスチレン重合体粒子の平均径ｄ₅₀は０．９０mmで偏
差係数Ｃｖ値は０．４１であった。得られた発泡性重合
体粒子を５５ml/gに予備発泡した。予備発泡粒子の表皮
部のセル膜厚は１．６μｍで内部のセル膜厚は１．２μ
ｍであった。予備発泡粒子を２４時間熟成し、実施例１
と同様の成形条件で成形を行った。得られた成形品表面
の最大陥没深さは８４μｍであった。Example 3 In Example 1, the polymerization conversion was 70% by weight and the polymerization temperature was 8%.
Suspension polymerization was carried out in the same manner as in Example 1 except that the temperature was raised from 6 ° C to 93 ° C to obtain expandable polymer particles. The expandable polystyrene polymer particles obtained had an average diameter d ₅₀ of 0.90 mm and a deviation coefficient Cv value of 0.41. The expandable polymer particles obtained were pre-expanded to 55 ml / g. The cell thickness of the skin of the pre-expanded particles is 1.6 μm, and the cell thickness inside is 1.2 μ.
It was m. The pre-expanded particles were aged for 24 hours, and Example 1 was used.
Molding was performed under the same molding conditions as. The maximum depression depth of the surface of the obtained molded product was 84 μm.

【００２４】比較例５ 実施例１において重合転化率６０重量％で１０２℃に昇
温した以外は実施例１と同様に懸濁重合を行い、発泡性
重合体粒子を得た。得られた発泡性ポリスチレン重合体
粒子の平均径ｄ₅₀は０．９６mmで偏差係数Ｃｖ値は０．
４９であり、一部巨大粒子が生成した。重合装置への重
合物の付着量は約３倍に増加した。得られた発泡性重合
体粒子を５５ml/gに予備発泡した。予備発泡粒子の表皮
部のセル膜厚は１．６μｍで内部のセル膜厚は０．８μ
ｍであった。予備発泡粒子を２４時間熟成し、実施例１
と同様の成形条件で成形を行った。得られた成形品表面
の最大陥没深さは８２μｍであった。以上の各実施例及
び比較例の重合条件及び粒子の特性を表１にまとめた。Comparative Example 5 Foamable polymer particles were obtained by carrying out suspension polymerization in the same manner as in Example 1 except that the temperature was raised to 102 ° C. at a polymerization conversion rate of 60% by weight. The expandable polystyrene polymer particles obtained had an average diameter d ₅₀ of 0.96 mm and a deviation coefficient Cv value of 0.
49, and some large particles were generated. The amount of the polymer deposited on the polymerizer increased about three times. The expandable polymer particles obtained were pre-expanded to 55 ml / g. The cell thickness of the skin part of the pre-expanded particles is 1.6 μm and the cell thickness inside is 0.8 μ.
It was m. The pre-expanded particles were aged for 24 hours, and Example 1 was used.
Molding was performed under the same molding conditions as. The maximum depression depth of the surface of the obtained molded product was 82 μm. Table 1 summarizes the polymerization conditions and particle characteristics of each of the above Examples and Comparative Examples.

【００２５】[0025]

【表１】 [Table 1]

【００２６】[0026]

【発明の効果】本発明によって安定した製法が提供さ
れ、またこれによって得られるビニル系重合体粒子は、
重合体粒子の粒径分布や他の発泡特性を損なうことなく
表面平滑性の優れた成形品を形成でき、本発明は生産性
及び品質の面から工業上極めて有益である。INDUSTRIAL APPLICABILITY The present invention provides a stable production method, and the vinyl-based polymer particles thus obtained are
A molded article having excellent surface smoothness can be formed without impairing the particle size distribution of the polymer particles and other foaming characteristics, and the present invention is industrially extremely useful in terms of productivity and quality.

Claims (4)

【特許請求の範囲】[Claims] 【請求項１】 ビニル系単量体と重合開始剤とを含む重
合性単量体混合物を難溶性燐酸塩と陰イオン界面活性剤
とを加えた水性媒体中で懸濁重合するのに際し、８０℃
〜９０℃の範囲の温度に昇温して重合を開始するととも
に重合転化率が４０重量％未満までの重合温度を８０℃
〜９０℃の範囲の温度とし、重合転化率が４０重量％〜
９５重量％の間で重合温度を少なくとも５℃以上上げて
９０℃〜１００℃の範囲の温度とすることを特徴とする
ビニル系重合体粒子の製造法。1. When suspension polymerizing a polymerizable monomer mixture containing a vinyl monomer and a polymerization initiator in an aqueous medium containing a sparingly soluble phosphate and an anionic surfactant, 80 ℃
Up to a temperature in the range of 90 ° C to start the polymerization, and the polymerization conversion rate until the polymerization conversion rate is less than 40% by weight is 80 ° C.
The temperature is in the range of ~ 90 ° C and the polymerization conversion rate is 40% by weight or more.
A method for producing vinyl polymer particles, characterized in that the polymerization temperature is increased by at least 5 ° C or more between 95% by weight to a temperature in the range of 90 ° C to 100 ° C. 【請求項２】 重合開始剤として半減期が１０時間とな
る温度が６５℃〜８０℃の範囲にある過酸化物系重合開
始剤を用いる請求項１記載のビニル系重合体粒子の製造
法。2. The method for producing vinyl polymer particles according to claim 1, wherein a peroxide polymerization initiator having a half-life of 10 hours at a temperature in the range of 65 ° C. to 80 ° C. is used as the polymerization initiator. 【請求項３】 重合開始剤としてｔ−ブチルペルオキシ
−２−エチルヘキサノエートを用いる請求項１記載のビ
ニル系重合体粒子の製造法。3. The method for producing vinyl polymer particles according to claim 1, wherein t-butylperoxy-2-ethylhexanoate is used as a polymerization initiator. 【請求項４】 請求項１、２又は３記載のビニル系重合
体粒子の製造法において、重合途中又は重合後、発泡剤
を含浸させることを特徴とする発泡性ビニル系重合体粒
子の製造法。4. The method for producing expandable vinyl polymer particles according to claim 1, 2 or 3, wherein a foaming agent is impregnated during or after the polymerization. .