JPH0545604B2 - - Google Patents

Description

【発明の詳細な説明】[Detailed description of the invention]

（産業上の利用分野） 本発明は粒径が比較的大きく、しかも形状が球
形の部分架橋した非晶質塩化ビニリデン系樹脂粒
子を高収率で容易に製造する方法を提供するもの
である。 また、本発明は部分架橋した非晶質塩化ビニリ
デン系樹脂粒子の粒径分布を制御する方法を提供
するものである。 本発明によつて得られる部分架橋した非晶質塩
化ビニリデン系樹脂粒子はビース発泡法による優
れた塩化ビニリデン系樹脂の発泡成形体を製造す
るための原料樹脂粒子として特に有用である。 （従来の技術） 断熱性、耐熱性等に優れた塩化ビニリデン系樹
脂のビーズ発泡法による発泡成形体が特開昭63−
170434号に記載され、部分架橋した非晶質塩化ビ
ニリデン系樹脂の製造方法が特開昭63−122713号
に記載されている。 ビーズ発泡法は樹脂粒子に揮発性発泡剤を含浸
し、直ちに或いは一定期間熟成し発泡性樹脂粒子
とし、これを直接発泡成形するか或いは一次発泡
後二次発泡成形し発泡成形体を製造する方法であ
る。ビーズ発泡法に使用される部分架橋した非晶
質塩化ビニリデン系樹脂粒子はその中心径が0.2
〜２mmの範囲にあり、粒径分布が極力狭く、粒子
形状が球状であるものが好ましい。 粒径が小さいと発泡剤の含浸に要する時間が短
かくて済むが、含浸後の粒子から発泡剤が逸散し
やすく、一次発泡後の発泡粒子からも発泡剤が逸
散しやすく、また発泡粒子への空気の浸入が多く
なり、それらのために二次発泡成形時の発泡倍率
が低下するし、成形体の断熱性等の物性が低下す
る。粒径が大きいと発泡剤の含浸に要する時間が
長くなり生産性が低下する。 中心径は目的とする発泡成形体により選定され
る。成形体中の原粒界面は往々にして融着不足や
空隙発生の問題を起こすので樹脂粒子の中心径は
大きい方が好ましく、断熱板の如き単純な形状の
成形体用であれば比較的大きい中心径の樹脂粒子
が使用される。しかし、細かい嵌合部や肉薄部を
有する成形体用には小さい中心径の樹脂粒子が使
用される。 粒径分布は用途にもよるが一般に狭い程好まし
い。粒径分布が広いと樹脂に対する発泡剤の含浸
量の割合が粒子毎に分布を生じ発泡成形体の物性
を低下させたり、成形体の外観が問題になる場合
等々があるからである。 また、樹脂粒子の形状は二次発泡成形の際の金
型へのスムースで均密な充填の観点等から真球に
近い程好ましい。 ビーズ発泡法で使用される部分架橋した非晶質
塩化ビニリデン系樹脂粒子は、一旦溶融して押出
造粒して製造することが困難なので、専ら縣濁重
合法により直接製造されている。しかし、通常の
縣濁重合法では縣濁安定剤の量を多く使用するこ
とにより中心径の小さい樹脂粒子は安定に製造で
きるが、中心径の比較的大きい樹脂粒子を安定に
製造することは困難である。大きい樹脂粒子を得
るには縣濁安定剤の量を少く、そして／または撹
拌を弱くする必要があるのであるが、これらの手
段はいずれも縣濁状態を不安定にする方向であ
り、重合途中で単量体、単量体・重合体混合物の
液滴が沈降、凝集、更には反応系全体の集塊化を
行こすからである。 また、通常の縣濁重合法では撹拌槽内の各位置
で流動エネルギー分布が存在すること及び液滴の
衝突に統計的確率分布が存在することから、単量
体、単量体・重合体混合物の液滴の分散・合一に
分布が生じることを避け難く、従つて得られる樹
脂粒子の粒径分布が広くなつてしまう欠点があ
る。 一方、スチレン系樹脂、塩化ビニル系樹脂、メ
タクリル酸メチル系樹脂、結晶性塩化ビニリデン
系樹脂等の製造技術の分野ではこれらの樹脂を縣
濁重合法により製造する方法がよく知られてい
る。特にビーズ発泡法により発泡成形体を製造す
ることが盛んに行われているスチレン系樹脂の製
造技術の分野では所望の中心径と狭い粒径分布を
持つたスチレン系樹脂粒子を縣濁重合により収率
よく製造する方法が多数提案されている。 これらの提案を大別すると、特公昭45−39459
号、特公昭46−21449号、特公昭62−51961号等の
縣濁安定剤に特徴のある方法（）、特開昭57−
10610号等の重合転化率10％程度塊状重合し、そ
の後縣濁重合に移ることを特徴とする方法（）、
特公昭40−824号、特開昭57−70111号等のスチレ
ン系樹脂をスチレン単量体に溶解後縣濁重合する
ことを特徴とする方法（）、特公昭46−2987号、
特公昭49−19111号等の予め粒径を揃えた未架橋
のスチレン系樹脂粒子を水中に分散させ、そこへ
樹脂粒子が膨潤するが溶解しない量のスチレンを
主体とする単量体を断続的または連続的に供給し
て縣濁重合することを特徴とする方法（）に分
類される。 前記（），（），（）の方法はいずれも重合
中に単量体、単量体・重合体混合物の液滴の分
散、合一に分布が存在することを避け難く、従つ
て得られる樹脂粒子の粒径分布は広く満足すべき
方法ではない。前記（）の方法はスチレンを主
体とする単量体を多く供給し過ぎるとスチレン系
樹脂粒子が単量体に溶解した溶液状態となり、こ
れが水中で分散、合一を起こし粒径分布が広くな
る。縣濁安定剤の量が少なければ場合によつては
重合系全体が不安定となり集塊化するし、多けれ
ば供給された単量体の単独液滴も生成し、これか
らの樹脂粒子が生成し粒径分布が広くなる。従つ
て、重合系内の単量体の単量体と重合体の和に対
する重量比を0.6程度以下に保つ必要があり、し
かも単量体、縣濁安定剤等の断続的または連続的
な供給が必要であり、管理面でも設備面でも複雑
で必ずしも満足すべき方法ではない。 （発明が解決しようとする問題点） 本発明者等が解決しようとする問題点は部分架
橋した非晶質塩化ビニリデン系樹脂粒子の製造に
おいても、粒径が比較的大きく、形状が球状であ
り、しかも粒径分布の制御された樹脂粒子を安定
に高収率で製造する方法を提供することにある。 （問題点を解決するための手段） 本発明者等は前記問題点を解決するために鋭意
研究を重ねた結果、ゲル分率が25〜85％である非
晶質塩化ビニリデン系樹脂粒子が常温から重合温
度近傍の温度において樹脂粒子重量の１〜20倍量
の塩化ビニリデンを主体とする共重合性不飽和単
量体を含浸すること、また、含浸された重合性不
飽和単量体は実質的に全量が原樹脂粒子内で重合
することを見出し、これらの知見に基づいて本発
明を完成した。 即ち、本発明はゲル分率が25％以上85％以下で
ある非晶質塩化ビニリデン系樹脂粒子をシード粒
子とし、膨潤度が該シード粒子の限界膨潤度の80
％以下となる量の塩化ビニリデンを主体とする共
重合性不飽和単量体及び架橋剤とラジカル重合開
始剤を該シード粒子に含浸せしめた後、縣濁安定
剤を添加して水性縣濁重合する（以下シード重合
と云う）ことを特徴とする部分架橋した非晶質塩
化ビニリデン系樹脂粒子の製造方法を提供するも
のである。以下に詳しく説明する。なお本発明に
云う限界膨潤度（以下LSI記す）とは樹脂粒子２
〜5gを過剰量のシード重合において使用する単
量体組成の混合液に常温、撹拌下１時間浸漬した
後、200メツシユの金網で濾過し金網上に残つた
単量体を含浸した状態の樹脂粒子の重量から次式
で求めた値である。 限界膨潤度≡LSI＝（単量体を含浸した状態の
樹脂粒子重量）／（浸漬前の樹脂粒子重量） また、本発明でいう膨潤度（以下SIと記す）と
はシード重合において使用するシード粒子の重量
（Ws）と単量体の全重量（Wm）から次式で求め
た値である。 膨潤度≡SI＝（Ws＋Wm）／Ws また、本発明でいうゲル分率とは樹脂１〜2g
を100mlのテトラヒドラフラン中に40℃、撹拌下
１時間浸漬した後、可溶分と不溶分を濾別し、テ
トラヒドロフランを蒸発除去して得られるテトラ
ヒドロフラン不溶分の重量から次式で求めた値で
ある。 ゲル分率（％）＝（不溶分の重量）×100／（浸漬
前の樹脂重量） まず、本発明のゲル分率が25％以上85％以下で
ある非晶質塩化ビニリデン系樹脂粒子（以下シー
ド粒子という）について説明する。 本発明のシード粒子は結晶性であるとLSIが低
く本発明の目的に適さない故、非晶質である必要
がある。一般に塩化ビニリデンより生成する構造
単位が85重量％以下の樹脂は非晶質である。ま
た、非晶質であつてもゲル分率が25％未満では単
量体を含浸した粒子はシード重合中に単量体を粒
子内に保持できず、ゲル分率が85％を越えると
LSIが低く本発明の目的に適さない故、ゲル分率
は25％以上85％以下である必要がある。 本発明のシード粒子は塩化ビニリデン30〜85
部、一種以上の共重合性不飽和単量体70〜15部及
び一種以上の共重合可能な二重結合を分子内に２
以上有する化合物（以下架橋剤と云う）とをラジ
カル重合開始剤、縣濁安定剤、必要に応じてPH調
整剤の存在下に公知の水性縣濁重合を行うことに
より得られる。 この場合、縣濁安定剤の量を多く使用し、そし
て／または撹拌を強くして始めから大部分をシー
ド粒子として得ることもできるし、直接にビーズ
発泡用原料樹脂粒子を得る目的で重合して得た樹
脂粒子から規格内の製品粒子を篩分し残部の規格
外の小粒子をシード粒子として得ることもでき、
また、残部の規格外の大粒子を粉砕してシード粒
子とすることもできる。 共重合性不飽和単量体としては塩化ビニル、ア
クリロニトリル、メタクリロニトリル、スチレ
ン、α−メチルスチレン、酢酸ビニル、アクリル
酸、メタクリル酸、アクリル酸アルキルエステ
ル、メタクリル酸アルキルエステル、アクリル酸
グリシジル、メタクリル酸グリシジル、Ｎ−フエ
ニルマレイミド、Ｎ−ヘキシルマレイミド、Ｎ−
２クロロフエニルマレイミド等のＮ−置換マレイ
ミド等公知の単量体を挙げることができる。 架橋剤としてはジビニルベンゼン、，エチレン
グリコール、プロピレングリコール、１・３−ブ
チレングリコール、１・６−ヘキサンジオール、
ネオペンチグリリコール等のジオールのジアクリ
ル酸エステルやジメタクリル酸エステル、トリメ
チロールプロパンのトリアクリル酸エステルやト
リメタクリル酸エステル、テトラアリルオキシエ
タン等公知の共重合可能な架橋剤を挙げることが
できる。 架橋剤の量を加減することによりゲル分率を加
減できるので、架橋剤の量はシード粒子のゲル分
率が25〜85％の範囲の所望の値となるよう決める
ことができる。 ラジカル重合開始剤、縣濁安定剤としては公知
のものが使用できる。 次に、シード重合について説明する。 シード重合においてはシード粒子の重量と塩化
ビニリデンと一種以上の共重合性不飽和単量体の
単量体合計重量はSIがLSIの80％以下である条件
を満足することが必須である。SIがLSIの80％以
下であれば単量体は実質的に全量がシード粒子に
含浸し、含浸した単量体は実質的に全量がシード
粒子内で重合するのである。シード粒子の粒径の
ほゞ（SI）1/3倍の球形の樹脂粒子を得ることが
できる。SIがLSIの80％を越えるとシード粒子に
含浸しない単量体が存在し、この余分の単量体が
単独で分散・縣濁し重合するので微細な粒子や数
個以上合着した凝集粒等を多量に含む粒径分布の
広い樹脂粒子を生成する。 シード粒子への単量体と架橋剤及びラジカル重
合開始剤の含浸は縣濁安定剤の実質的不存在下で
シード粒子を水、単量体、架橋剤、ラジカル重合
開始剤と重合開始温度以下の温度で撹拌混合する
ことにより達成することができる。含浸操作時に
縣濁安定剤が存在するとシード粒子に含浸しない
単独の油滴も生成するので縣濁安定剤は実質的に
存在してはならない。 次いで縣濁安定剤を添加撹拌することにより、
単量体等を含浸し合着しているシード粒子は個々
にきれいに分散する。所定の温度に昇温して縣濁
重合を行えば単量体は実質的に全量が膨潤拡大し
たシード粒子内で重合し、シード粒子の粒径分布
とSIから決定される所期の粒径分布を有する樹脂
粒子を得ることができる。 縣濁安定剤の量は単量体等を含浸し合着してい
るシード粒子を個々にきれいに分散し、また重合
中に粒子同志が合着しない量であればよく、撹拌
強さは単量体等を含浸し合着しているシード粒子
を個々に分散でき、また重合中に個々の粒子が沈
降しない強さであればよい。 本発明のシード重合によれば生成粒子の粒径分
布はシード粒子の粒径分布とSIにより決定され縣
濁安定剤の種類や量、撹拌の強さには実質的に影
響を受けない。 シード重合に使用する塩化ビニリデンの量は30
〜85部が好ましく、一種以上の共重合性不飽和単
量体の量は70〜15部が好ましい（シード重合の説
明における部はシード重合において使用する塩化
ビニリデンと一種以上の共重合性不飽和単量体の
単量体合計重量を100部とする値である）。 塩化ビニリデンが30部未満では得られる樹脂の
難燃性、ガスバリヤー性、耐薬品性等塩化ビニリ
デン本来の特性が低下し、85部を越えると樹脂に
結晶性が発現しビーズ発泡のための発泡剤の含浸
性が低下する。 シード重合で使用する共重合性不飽和単量体と
してはシード粒子の説明において挙げた如き公知
の共重合可能な不飽和単量体が使用できる。 シード重合で使用する架橋剤としてはシード粒
子の説明において挙げた如き公知の架橋剤が使用
できる。架橋剤の種類、量はビーズ発泡のための
発泡剤の含浸性、発泡過程での発泡性、発泡成形
体の独立気泡率等を勘案して決定することができ
る。 シード重合に使用する縣濁安定剤としてはヒド
ロキシプロピルメチルセルロース系、ポリビニル
アルコール系縣濁安定剤にその他各種の公知の縣
濁安定剤を使用することができる。 シード重合に使用する水の量は90〜150部が適
当である。 シード重合に使用されるラジカル重合開始剤は
ラウリルパーオキサイド、ベンゾイルパーオキサ
イド等公知の油溶性開始剤を使用することができ
る。 以上説明したように、本発明は部分架橋構造を
有するシード粒子の膨潤拡大した網目構造内に含
浸した単量体が実質的に全量シード粒子内で重合
する機構の重合法であり、従つてシード粒子の粒
径分布とSIを選定することにより粒径制御を行う
縣濁重合法であつて、縣濁安定剤の量や種類、撹
拌の強さ、単量体・重合体混合物の液滴粘度、或
いは未架橋の樹脂粒子に少量づつ単量体を添加し
ていくこと等により粒径制御を行う従来の縣濁重
合法とは全く異る新規な方法である。 本発明によれば目標の粒径分布を有する製品樹
脂粒子を予めシード粒子の粒径分布とSIを選定す
ることにより安定に高収率で製造することができ
る。 また、本発明によれば規格外の樹脂粒子を規格
内に回収救済することができる。 以下、本発明を実施例によつて更に詳細に説明
するが、これらの例により限定されるものではな
い。なを、実施例中の部は重量部を表わす。 実施例１〜４、比較例１〜３ 水120部に縣濁安定剤としてPVA 0.3部を予め
溶解した溶液を反応容器に仕込み、次にＮ−フエ
ニルマレイミド７部をアクリロニトリル20部、ス
チレン23部、ジビニルベンゼンを表１に示す量の
混合液に予め溶解させ、更に塩化ビニリデン50部
を混合した単量体混合液とラジカル重合開始剤と
してラウリルパーオキサイド0.8部を仕込んだ。
窒素置換後、撹拌を開始し60℃に昇温後26.5時間
に反応し、生成樹脂粒子を濾別、水洗、乾燥し
た。得られた樹脂粒子中の残存単量体量はいずれ
も1.5％以下であり、重合率はいずれも98％以上
であつた。 篩分して得た粒径0.3〜0.4mmの樹脂粒子のゲル
分率と限界膨潤度は表１に示す値であつた。 次に水110部と得られた粒径0.3〜0.4mmの樹脂
粒子20部を反応容器に仕込み、Ｎ−フエニルマレ
イミド７部、アクリロニトリル20部、スチレン23
部、塩化ビニリデン50部、ジビニルベンゼン0.03
部の単量体混合液とラウリルパーオキサイド0.8
部を仕込んだ後、１時間撹拌した。次いで
PVA0.3部を水14部に溶解した水溶液を添加後窒
素置換し、40分間撹拌後60℃に昇温し26.5時間反
応した。瀘別、水洗、乾燥して、得られた樹脂粒
子の残存単量体量はいずれも1.5％以下であり、
重合率はいずれも98％以上であつた。また、粒径
分布、粒子形状、ゲル分率は表１に示す性状であ
つた。 (Industrial Application Field) The present invention provides a method for easily producing partially crosslinked amorphous vinylidene chloride resin particles having a relatively large particle size and a spherical shape at a high yield. The present invention also provides a method for controlling the particle size distribution of partially crosslinked amorphous vinylidene chloride resin particles. The partially crosslinked amorphous vinylidene chloride resin particles obtained by the present invention are particularly useful as raw material resin particles for producing excellent vinylidene chloride resin foam moldings by the beads foaming method. (Prior art) A foamed molded product made by the bead foaming method of vinylidene chloride resin, which has excellent heat insulation properties and heat resistance, was published in JP-A-63-
170434, and a method for producing a partially crosslinked amorphous vinylidene chloride resin is described in JP-A-63-122713. The bead foaming method is a method in which resin particles are impregnated with a volatile foaming agent, and then aged immediately or for a certain period of time to form foamable resin particles, which are then directly foam-molded or primary foamed and then secondary foam-molded to produce a foamed molded product. It is. The partially crosslinked amorphous vinylidene chloride resin particles used in the bead foaming method have a center diameter of 0.2
Preferably, the particle diameter is in the range of 2 mm, the particle size distribution is as narrow as possible, and the particle shape is spherical. If the particle size is small, the time required for impregnation with the blowing agent will be short, but the blowing agent will easily escape from the particles after impregnation, and the blowing agent will also easily escape from the expanded particles after primary foaming. More air enters the particles, which reduces the expansion ratio during secondary foam molding and reduces the physical properties of the molded product, such as heat insulation. If the particle size is large, the time required for impregnation with the blowing agent becomes longer and productivity decreases. The center diameter is selected depending on the intended foam molded product. Since the raw particle interface in a molded product often causes problems such as insufficient fusion and the generation of voids, it is preferable that the center diameter of the resin particle is large, and it is relatively large for a molded product with a simple shape such as a heat insulating board. Median diameter resin particles are used. However, resin particles with a small center diameter are used for molded bodies having fine fitting parts or thin parts. Although the particle size distribution depends on the application, in general, the narrower the particle size distribution, the better. This is because if the particle size distribution is wide, the ratio of the impregnated amount of the blowing agent to the resin will be distributed for each particle, which may deteriorate the physical properties of the foam molded product or cause problems with the appearance of the molded product. Further, the shape of the resin particles is preferably as close to a true sphere as possible from the viewpoint of smooth and uniform filling into a mold during secondary foam molding. Partially crosslinked amorphous vinylidene chloride resin particles used in the bead foaming method are difficult to manufacture by once melting and extrusion granulation, so they are directly manufactured exclusively by the suspension polymerization method. However, in the normal suspension polymerization method, resin particles with a small center diameter can be stably produced by using a large amount of suspension stabilizer, but it is difficult to stably produce resin particles with a relatively large center diameter. It is. In order to obtain large resin particles, it is necessary to reduce the amount of suspension stabilizer and/or weaken the stirring, but all of these methods tend to make the suspension unstable, and during polymerization, This is because droplets of monomers and monomer/polymer mixtures precipitate, coagulate, and even agglomerate the entire reaction system. In addition, in the normal suspension polymerization method, there is a flow energy distribution at each position in the stirring tank and a statistical probability distribution exists in the collision of droplets. It is difficult to avoid the occurrence of distribution in the dispersion and coalescence of the droplets, resulting in a disadvantage that the resulting resin particles have a wide particle size distribution. On the other hand, in the field of manufacturing technology for styrene resins, vinyl chloride resins, methyl methacrylate resins, crystalline vinylidene chloride resins, etc., methods for manufacturing these resins by suspension polymerization are well known. In particular, in the field of styrenic resin manufacturing technology where foam moldings are frequently produced by bead foaming, styrenic resin particles with a desired center diameter and narrow particle size distribution are collected by suspension polymerization. Many efficient manufacturing methods have been proposed. Broadly speaking, these proposals can be divided into
No. 46-21449, Japanese Patent Publication No. 62-51961, etc., methods characteristic of suspension stabilizers (), JP-A-57-
10610, etc., which is characterized by bulk polymerization with a polymerization conversion rate of about 10%, and then proceeding to suspension polymerization (),
JP-B No. 40-824, JP-A-57-70111, etc., a method characterized by dissolving a styrene resin in a styrene monomer and then subjecting it to suspension polymerization (); JP-B No. 46-2987;
Uncrosslinked styrene-based resin particles with a uniform particle size in advance, such as Japanese Patent Publication No. 49-19111, are dispersed in water, and a monomer mainly composed of styrene is intermittently added thereto in an amount that causes the resin particles to swell but not dissolve. Alternatively, it is classified as a method characterized by continuous feeding and suspension polymerization (). In all of the above methods (), (), and (), it is difficult to avoid the existence of distribution in the dispersion and coalescence of droplets of monomers and monomer/polymer mixtures during polymerization, and therefore The particle size distribution of resin particles is not universally satisfactory. In the method () above, if too much monomer mainly composed of styrene is supplied, the styrene resin particles become dissolved in the monomer and become a solution, which disperses and coalesces in water, resulting in a wide particle size distribution. . If the amount of suspension stabilizer is small, the entire polymerization system may become unstable and agglomerate, and if it is too large, individual droplets of the supplied monomer will also be formed, and future resin particles will be formed. The particle size distribution becomes wider. Therefore, it is necessary to maintain the weight ratio of the monomer to the sum of the monomer and the polymer in the polymerization system to about 0.6 or less, and to supply the monomer, suspension stabilizer, etc. intermittently or continuously. This method is complicated in terms of management and equipment, and is not necessarily a satisfactory method. (Problems to be Solved by the Invention) The problems to be solved by the present inventors are that even in the production of partially crosslinked amorphous vinylidene chloride resin particles, the particle size is relatively large and the shape is spherical. The object of the present invention is to provide a method for stably producing resin particles with a controlled particle size distribution at a high yield. (Means for Solving the Problems) As a result of extensive research in order to solve the above problems, the present inventors have found that amorphous vinylidene chloride resin particles with a gel fraction of 25 to 85% are available at room temperature. impregnation with a copolymerizable unsaturated monomer mainly consisting of vinylidene chloride in an amount of 1 to 20 times the weight of the resin particles at a temperature near the polymerization temperature, and that the impregnated polymerizable unsaturated monomer is substantially It was discovered that the entire amount was polymerized within the raw resin particles, and the present invention was completed based on these findings. That is, in the present invention, amorphous vinylidene chloride resin particles having a gel fraction of 25% or more and 85% or less are used as seed particles, and the swelling degree is 80% of the limit swelling degree of the seed particles.
After impregnating the seed particles with a copolymerizable unsaturated monomer mainly consisting of vinylidene chloride, a crosslinking agent, and a radical polymerization initiator in an amount of not more than 50%, a suspension stabilizer is added to carry out aqueous suspension polymerization. The present invention provides a method for producing partially crosslinked amorphous vinylidene chloride resin particles, which is characterized by carrying out (hereinafter referred to as seed polymerization) amorphous vinylidene chloride resin particles. This will be explained in detail below. In addition, the critical degree of swelling (hereinafter referred to as LSI) referred to in the present invention is the resin particle 2
~5g was immersed in an excessive amount of a mixed solution of the monomer composition used in seed polymerization for 1 hour at room temperature with stirring, and then filtered through a 200-mesh wire mesh to obtain a resin impregnated with the monomer remaining on the wire mesh. This value is calculated from the weight of the particles using the following formula. Limit swelling degree ≡ LSI = (weight of resin particles impregnated with monomer) / (weight of resin particles before soaking) In addition, the degree of swelling (hereinafter referred to as SI) in the present invention refers to the degree of swelling of the seed used in seed polymerization. This value is calculated from the particle weight (Ws) and the total monomer weight (Wm) using the following formula. Swelling degree≡SI=(Ws+Wm)/Ws In addition, the gel fraction in the present invention is 1 to 2 g of resin.
was immersed in 100 ml of tetrahydrofuran at 40℃ for 1 hour with stirring, the soluble and insoluble components were separated by filtration, and the tetrahydrofuran was removed by evaporation.The value was determined from the weight of the tetrahydrofuran insoluble component obtained using the following formula. It is. Gel fraction (%) = (weight of insoluble matter) x 100 / (resin weight before immersion) First, the amorphous vinylidene chloride resin particles of the present invention having a gel fraction of 25% or more and 85% or less (hereinafter referred to as (referred to as seed particles) will be explained. The seed particles of the present invention need to be amorphous because crystalline particles have a low LSI and are not suitable for the purpose of the present invention. Generally, resins containing 85% by weight or less of structural units derived from vinylidene chloride are amorphous. Furthermore, even if the particles are amorphous, if the gel fraction is less than 25%, the monomer-impregnated particles will not be able to retain the monomer within the particles during seed polymerization, and if the gel fraction exceeds 85%,
Since the LSI is low and it is not suitable for the purpose of the present invention, the gel fraction needs to be 25% or more and 85% or less. The seed particles of the present invention are vinylidene chloride 30-85
part, 70 to 15 parts of one or more copolymerizable unsaturated monomers and two or more copolymerizable double bonds in the molecule.
It is obtained by carrying out known aqueous suspension polymerization of the compound having the above (hereinafter referred to as a crosslinking agent) in the presence of a radical polymerization initiator, a suspension stabilizer, and, if necessary, a PH regulator. In this case, it is possible to obtain most of the seed particles from the beginning by using a large amount of suspension stabilizer and/or by strengthening the stirring, or by polymerizing directly to obtain raw material resin particles for bead foaming. It is also possible to sieve product particles that meet the specifications from the resin particles obtained by sieving and obtain the remaining small particles that do not meet the specifications as seed particles.
Further, the remaining non-standard large particles can be pulverized to form seed particles. Copolymerizable unsaturated monomers include vinyl chloride, acrylonitrile, methacrylonitrile, styrene, α-methylstyrene, vinyl acetate, acrylic acid, methacrylic acid, acrylic acid alkyl ester, methacrylic acid alkyl ester, glycidyl acrylate, and methacrylate. Glycidyl acid, N-phenylmaleimide, N-hexylmaleimide, N-
Known monomers such as N-substituted maleimides such as 2-chlorophenylmaleimide can be mentioned. As a crosslinking agent, divinylbenzene, ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,6-hexanediol,
Known copolymerizable crosslinking agents include diacrylic esters and dimethacrylic esters of diols such as neopentyglylicol, triacrylic esters and trimethacrylic esters of trimethylolpropane, and tetraallyloxyethane. Since the gel fraction can be adjusted by adjusting the amount of crosslinking agent, the amount of crosslinking agent can be determined so that the gel fraction of the seed particles has a desired value in the range of 25 to 85%. Known radical polymerization initiators and suspension stabilizers can be used. Next, seed polymerization will be explained. In seed polymerization, it is essential that the weight of the seed particles and the total monomer weight of vinylidene chloride and one or more copolymerizable unsaturated monomers satisfy the condition that SI is 80% or less of LSI. When SI is 80% or less of LSI, substantially all of the monomer is impregnated into the seed particles, and substantially all of the impregnated monomer is polymerized within the seed particles. It is possible to obtain spherical resin particles that are approximately (SI) 1/3 times the particle size of the seed particles. If the SI exceeds 80% of the LSI, there will be monomers that are not impregnated into the seed particles, and this excess monomer will be dispersed, suspended, and polymerized by itself, resulting in fine particles and agglomerated particles in which several or more pieces have coalesced. produces resin particles with a wide particle size distribution containing a large amount of Impregnation of the monomer, crosslinking agent, and radical polymerization initiator into the seed particles is carried out in the substantial absence of a suspension stabilizer. This can be achieved by stirring and mixing at a temperature of . The presence of a suspension stabilizer during the impregnation operation results in the formation of individual oil droplets that do not impregnate the seed particles, so the suspension stabilizer must be substantially absent. Next, by adding a suspension stabilizer and stirring,
Seed particles impregnated with monomers and the like are individually and neatly dispersed. When the temperature is raised to a predetermined temperature and suspension polymerization is performed, substantially all of the monomer polymerizes within the swollen and expanded seed particles, resulting in the desired particle size determined from the particle size distribution and SI of the seed particles. Resin particles having a uniform distribution can be obtained. The amount of suspension stabilizer should be such that the seed particles that have been impregnated with monomers etc. and are coalesced can be individually and neatly dispersed, and that the particles do not coalesce during polymerization, and the stirring strength should be adjusted according to the monomer content. Any strength may be sufficient as long as it can individually disperse the seed particles impregnated and bonded together, and that the individual particles do not settle during polymerization. According to the seed polymerization of the present invention, the particle size distribution of the produced particles is determined by the particle size distribution of the seed particles and SI, and is substantially unaffected by the type and amount of the suspension stabilizer and the strength of stirring. The amount of vinylidene chloride used for seed polymerization is 30
~85 parts is preferred, and the amount of one or more copolymerizable unsaturated monomers is preferably 70 to 15 parts (in the description of seed polymerization, parts refer to vinylidene chloride used in seed polymerization and one or more copolymerizable unsaturated monomers). (The value is based on the total weight of monomers being 100 parts). If the amount of vinylidene chloride is less than 30 parts, the original properties of vinylidene chloride such as flame retardancy, gas barrier properties, and chemical resistance will deteriorate, and if it exceeds 85 parts, the resin will develop crystallinity and will be difficult to foam for bead foaming. The impregnating properties of the agent are reduced. As the copolymerizable unsaturated monomer used in the seed polymerization, the known copolymerizable unsaturated monomers mentioned in the description of the seed particles can be used. As the crosslinking agent used in the seed polymerization, known crosslinking agents such as those mentioned in the explanation of the seed particles can be used. The type and amount of the crosslinking agent can be determined by taking into consideration the impregnating property of the foaming agent for bead foaming, the foamability during the foaming process, the closed cell ratio of the foamed molded product, etc. As the suspension stabilizer used in seed polymerization, hydroxypropyl methylcellulose-based suspension stabilizers, polyvinyl alcohol-based suspension stabilizers, and various other known suspension stabilizers can be used. The appropriate amount of water used for seed polymerization is 90 to 150 parts. As the radical polymerization initiator used in the seed polymerization, known oil-soluble initiators such as lauryl peroxide and benzoyl peroxide can be used. As explained above, the present invention is a polymerization method in which substantially all of the monomer impregnated into the swollen and expanded network structure of seed particles having a partially crosslinked structure is polymerized within the seed particles. It is a suspension polymerization method that controls the particle size by selecting the particle size distribution and SI of the particles, the amount and type of suspension stabilizer, the strength of stirring, and the droplet viscosity of the monomer/polymer mixture. This is a new method that is completely different from conventional suspension polymerization methods in which particle size is controlled by adding a monomer little by little to uncrosslinked resin particles. According to the present invention, product resin particles having a target particle size distribution can be stably produced at a high yield by selecting the particle size distribution and SI of the seed particles in advance. Further, according to the present invention, non-standard resin particles can be recovered and repaired to within the standard. EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to these examples. In the examples, parts represent parts by weight. Examples 1 to 4, Comparative Examples 1 to 3 A solution prepared by dissolving 0.3 parts of PVA as a suspension stabilizer in 120 parts of water was charged into a reaction vessel, and then 7 parts of N-phenylmaleimide, 20 parts of acrylonitrile, and 23 parts of styrene were charged. 1 part, divinylbenzene was dissolved in advance in a mixed solution in the amount shown in Table 1, and a monomer mixed solution containing 50 parts of vinylidene chloride and 0.8 parts of lauryl peroxide as a radical polymerization initiator were charged.
After purging with nitrogen, stirring was started and the temperature was raised to 60°C, followed by reaction for 26.5 hours, and the resulting resin particles were separated by filtration, washed with water, and dried. The residual monomer content in the obtained resin particles was all 1.5% or less, and the polymerization rate was all 98% or more. The gel fraction and limit swelling degree of the resin particles having a particle size of 0.3 to 0.4 mm obtained by sieving were the values shown in Table 1. Next, 110 parts of water and 20 parts of the resulting resin particles with a particle size of 0.3 to 0.4 mm were charged into a reaction vessel, followed by 7 parts of N-phenylmaleimide, 20 parts of acrylonitrile, and 23 parts of styrene.
parts, vinylidene chloride 50 parts, divinylbenzene 0.03 parts
0.8 parts monomer mixture and lauryl peroxide
After adding a portion, the mixture was stirred for 1 hour. then
After adding an aqueous solution of 0.3 parts of PVA dissolved in 14 parts of water, the mixture was purged with nitrogen, stirred for 40 minutes, heated to 60°C, and reacted for 26.5 hours. After filtering, washing with water, and drying, the residual monomer content of the resin particles obtained is all 1.5% or less,
The polymerization rate was 98% or more in all cases. Further, the particle size distribution, particle shape, and gel fraction were as shown in Table 1.

【表】 実施例５〜７、比較例４ 水120部にPVA0.3部を予め溶解した溶液を反
応容器に仕込み、次にＮ−フエニルマレイミド７
部をアクリロニトリル20部、スチレン23部、１・
６−ヘキサンジオールジアクリレート0.07部の混
合液に予め溶解させ、更に塩化ビニリデン50部と
ラウリルパーオサイド0.8部を混合した単量体混
合液を仕込んだ。窒素置換後、100rpmの速度で
撹拌を開始し60℃に昇温後26.5時間反応した。生
成樹脂粒子を濾別、水洗、乾燥して得られた樹脂
粒子の残存単量体量は1.5％以下であり、重合率
は98％以上であつた。また粒径分布は次の通りで
あつた。 粒径(mm) 含有率(%) 0.2以下 ４ 0.2〜0.4 28 0.4〜0.6 18 0.6〜0.8 14 0.8〜1.0 12 1.0〜1.2 10 1.2〜2.0 14 次ぎに、得られた樹脂粒子の粒径が0.2〜0.4mm
の粒子をそれぞれ表２に示す量と水110部を反応
容器に仕込み、Ｎ−フエニルマレイミド７部、ア
クリロニトリル20部、塩化ビニリデン50部、１・
６−ヘキサンジオールジアクリレート0.06部ラウ
リルパーオキサイド0.8部の単量体混合液を仕込
んだ後、１時間100rpmで撹拌し、続けてPVA0.3
部を水14部に溶解した水溶液を添加後窒素置換
し、速度を130rpmに上げて40分間撹拌後60℃に
昇温し26.5時間反応した。濾別、水洗、乾燥して
得られた樹脂粒子の残留単量体はずれもは1.5％
以下、重合率はいずれも98％以上、ゲル分率はい
ずれも50〜55％であり、粒径分布は表２に示す値
であつた。[Table] Examples 5 to 7, Comparative Example 4 A solution prepared by dissolving 0.3 parts of PVA in 120 parts of water was charged into a reaction vessel, and then N-phenylmaleimide 7
20 parts acrylonitrile, 23 parts styrene, 1 part
A monomer mixture prepared by dissolving 0.07 parts of 6-hexanediol diacrylate in advance and mixing 50 parts of vinylidene chloride and 0.8 parts of lauryl peroxide was charged therein. After purging with nitrogen, stirring was started at a speed of 100 rpm, the temperature was raised to 60°C, and the reaction was continued for 26.5 hours. The residual monomer content of the resin particles obtained by filtering, washing with water, and drying the produced resin particles was 1.5% or less, and the polymerization rate was 98% or more. The particle size distribution was as follows. Particle size (mm) Content (%) 0.2 or less 4 0.2-0.4 28 0.4-0.6 18 0.6-0.8 14 0.8-1.0 12 1.0-1.2 10 1.2-2.0 14 Next, the particle size of the obtained resin particles is 0.2 ~0.4mm
Particles in the amounts shown in Table 2 and 110 parts of water were charged into a reaction vessel, and 7 parts of N-phenylmaleimide, 20 parts of acrylonitrile, 50 parts of vinylidene chloride, and 1.
After adding a monomer mixture of 0.06 parts of 6-hexanediol diacrylate and 0.8 parts of lauryl peroxide, the mixture was stirred at 100 rpm for 1 hour, and then PVA0.3
After adding an aqueous solution in which 1 part was dissolved in 14 parts of water, the mixture was purged with nitrogen, the speed was increased to 130 rpm, and after stirring for 40 minutes, the temperature was raised to 60°C and reacted for 26.5 hours. Residual monomer content in resin particles obtained by filtration, water washing, and drying is 1.5%.
The polymerization rate was 98% or more, the gel fraction was 50 to 55%, and the particle size distribution was as shown in Table 2.

【表】 なお、仕込んだ0.2〜0.4mmの樹脂粒子のゲル分
率は54％であり、限界膨潤度は10であつた。実施
例５〜７の樹脂粒子は球形であり、異形粒、凝集
粒はほとんど見つからない。比較例４の0.8mm以
上の樹脂には異形粒、凝集粒が多い。 比較例 ５ 撹拌速度を70rpmとした以外は実施例５の前段
の反応と同じ条件で反応を行つた。反応終了後、
反応容器の蓋を開けたところ、撹拌翼の周辺以外
樹脂粒子が全体に凝集していた。 比較例 ６ 撹拌速度を130rpmとした以外実施例５の前段
の反応と同じ条件で反応を行つた。反応終了後、
反応容器の蓋を開けたところ、撹拌翼上部に約20
％の樹脂凝集塊が付着していた。 実施例 ８ 実施例１の前段の重合で得た粒径が0.6〜0.8mm
の樹脂粒子を仕込んだことと撹拌速度を160rpm
とした以外は実施例６と同じ条件で後段の反応、
後処理を行つた。得られた樹脂粒子の粒径分布は
次に示す値であつた。 粒径(mm) 含有率(重量%) 0.6以下 ２ 0.6〜0.8 １ 0.8〜1.0 １ 1.0〜1.2 17 1.2〜1.6 78 1.6以上 １ なお、仕込んだ0.6〜0.8mmの樹脂粒子のゲル分
率は54％であり、限界膨潤度は10であつた。ま
た、樹脂粒子の形状は球形であり、異形粒、凝集
粒は殆んど含まれていなかつた。 実施例 ８ 水120部に縣濁安定剤としてヒトロキジプロピ
ルメチルセルロース0.2部を溶解した溶液を反応
容器に仕込み、メタクリル酸メチル50部、塩化ビ
ニリデン50部、ジビニルベンゼン0.04部、ジイソ
プロピルパーオシジカーボネート0.2部の混合液
を仕込んだ。窒素置換後、撹拌を開始し40℃に昇
温後24時間反応し、生成樹脂粒子を濾別、水洗、
乾燥した。得られた樹脂粒子中の残存単量体量は
1.3％であり、重合率は98％以上であつた。篩分
して得た粒径0.2〜0.4mmの樹脂のゲル分率は47％
であり、塩化ビニリデン50部、アクリロニトリル
30部、スチレン15部、Ｎ−フエニルマレイミド５
部の単量体混合液に対する限界膨潤度は14であっ
た。 次に、水110部と得られた粒径0.2〜0.4mmの樹
脂粒子20部を実施例５と同じ反応容器に仕込み、
塩化ビニリデン50部、アクリロニトリル30部、ス
チレン15部、Ｎ−フエニルマレイミド５部、ジビ
ニルベンゼン0.02部ラウリルパーオキサイド0.6
部よりなる単量体混合液を仕込んだ後、１時間
100rpmで撹拌し、続けてヒドロキシプロピルメ
チルセルロース0.2部を水14部に溶解した水溶液
を添加後、窒素置換し、速度を130rpmに上げて
40分間撹拌後60℃に昇温し24時間反応した。濾
過、水洗、乾燥して得られた樹脂粒子の残存単量
体は1.3％、重合率は98％以上、ゲル分率は41％
であり、粒径分布は次に示す値であつた。 粒径(mm) 含有率(重量%) 0.2以下 ３ 0.2〜0.4 ７ 0.4〜0.6 58 0.6〜0.8 30 0.8〜1.0 １ 1.0以上 １[Table] The gel fraction of the charged resin particles of 0.2 to 0.4 mm was 54%, and the limit swelling degree was 10. The resin particles of Examples 5 to 7 were spherical, and almost no irregularly shaped particles or agglomerated particles were found. The resin of Comparative Example 4 with a diameter of 0.8 mm or more contained many irregularly shaped particles and agglomerated particles. Comparative Example 5 A reaction was carried out under the same conditions as in the first stage of Example 5, except that the stirring speed was 70 rpm. After the reaction is complete,
When the lid of the reaction vessel was opened, resin particles were found to have aggregated all over the area except around the stirring blades. Comparative Example 6 A reaction was carried out under the same conditions as in the first stage of Example 5 except that the stirring speed was 130 rpm. After the reaction is complete,
When the lid of the reaction vessel was opened, about 20
% of resin aggregates were attached. Example 8 The particle size obtained in the first stage polymerization of Example 1 was 0.6 to 0.8 mm.
of resin particles and the stirring speed was set to 160 rpm.
The subsequent reaction was carried out under the same conditions as in Example 6 except that
Post-processing was performed. The particle size distribution of the obtained resin particles was as shown below. Particle size (mm) Content (weight %) 0.6 or less 2 0.6 to 0.8 1 0.8 to 1.0 1 1.0 to 1.2 17 1.2 to 1.6 78 1.6 or more 1 The gel fraction of the charged resin particles of 0.6 to 0.8 mm is 54 %, and the critical swelling degree was 10. Further, the shape of the resin particles was spherical, and almost no irregularly shaped particles or agglomerated particles were included. Example 8 A solution prepared by dissolving 0.2 parts of hydroxypropyl methylcellulose as a suspension stabilizer in 120 parts of water was charged into a reaction vessel, followed by 50 parts of methyl methacrylate, 50 parts of vinylidene chloride, 0.04 parts of divinylbenzene, and 0.2 parts of diisopropyl perosydicarbonate. A mixture of 1 part and 1 part was added. After replacing with nitrogen, start stirring, raise the temperature to 40℃, react for 24 hours, separate the formed resin particles by filtration, wash with water,
Dry. The amount of residual monomer in the obtained resin particles is
The polymerization rate was 1.3%, and the polymerization rate was 98% or more. The gel fraction of the resin with a particle size of 0.2 to 0.4 mm obtained by sieving is 47%.
50 parts vinylidene chloride, acrylonitrile
30 parts, styrene 15 parts, N-phenylmaleimide 5
The critical swelling degree for the monomer mixture was 14. Next, 110 parts of water and 20 parts of the obtained resin particles with a particle size of 0.2 to 0.4 mm were charged into the same reaction vessel as in Example 5.
Vinylidene chloride 50 parts, acrylonitrile 30 parts, styrene 15 parts, N-phenylmaleimide 5 parts, divinylbenzene 0.02 parts lauryl peroxide 0.6 parts
1 hour after charging the monomer mixture consisting of
Stir at 100 rpm, then add an aqueous solution of 0.2 parts of hydroxypropyl methylcellulose dissolved in 14 parts of water, replace with nitrogen, and increase the speed to 130 rpm.
After stirring for 40 minutes, the temperature was raised to 60°C and the mixture was reacted for 24 hours. The residual monomer content of the resin particles obtained by filtration, water washing, and drying is 1.3%, the polymerization rate is over 98%, and the gel fraction is 41%.
The particle size distribution was as shown below. Particle size (mm) Content (% by weight) 0.2 or less 3 0.2-0.4 7 0.4-0.6 58 0.6-0.8 30 0.8-1.0 1 1.0 or more 1

Claims (1)

【特許請求の範囲】[Claims] １ ゲル分率が25％以上85％以下である非晶質塩
化ビニリデン系樹脂粒子をシード粒子とし、膨潤
度が該シード粒子の限界膨潤度の80％以下となる
量の塩化ビニリデンを主体とする共重合性不飽和
単量体及び架橋剤、ラジカル重合開始剤を該シー
ド粒子に含浸せしめた後、縣濁安定剤を添加して
水性縣濁重合することを特徴とする部分架橋した
非晶質塩化ビニリデン系樹脂粒子の製造方法。1 Seed particles are amorphous vinylidene chloride resin particles with a gel fraction of 25% or more and 85% or less, and vinylidene chloride is used as the main ingredient in an amount such that the degree of swelling is 80% or less of the limit swelling degree of the seed particles. A partially crosslinked amorphous material characterized in that the seed particles are impregnated with a copolymerizable unsaturated monomer, a crosslinking agent, and a radical polymerization initiator, and then a suspension stabilizer is added to carry out aqueous suspension polymerization. A method for producing vinylidene chloride resin particles.