JP3581173B2 - Various methods for controlling surface morphology of ABS resin - Google Patents

Description

本発明で言う温度変動率（Ｔ_ｄｅ：１時間あたりの温度変動率）は下記式（数２）で算出される。
【００３１】
【数２】
温度変動率（Ｔ_ｄｅ＝（（Ｔ_ｍａｘ −Ｔ_ｍｉｎ ）／Ｔ_ＡＶ）×１００
（但しＴ_ｍａｘ は１時間当たりの回収温度の最大温度、Ｔ_ｍｉｎ は最小温度）
また１時間当たりの温度の変動回数を毎時温度変動回数（Ｎ_ＣＴ）とよび（但し温度変動率０．５％以内の変動は無視する）、時間に対し温度の微分値が正負に変化する回数をさす。
【００３２】
本発明において回収温度の平均値Ｔ_ＡＶ、温度変動率Ｔ_ｄｅ、及び１時間当たりの温度の変動回数Ｎ_ＣＴは３時間以上の回収温度の平均値を一定にして運転し、その区間の測定値から算出する。
【００３３】
上記Ｔ_ｄｅとＮ_ＣＴの積（Ｆ）を調整することにより成形加工後成形物表面で粒子Ｂとなるうる粒子が生成する。本発明では上記Ｆの値が０．５〜１５０のものが使用でき、特にＦの値が異なる２種以上の樹脂を混合して使用すると好ましい結果を与える。この際も混合比とＦ値から平均値を求めてこれが０．５〜１５０の範囲に入るものが使用できる。例えばＦが０．５〜１５では粒子Ｂは０．０１〜１％生成し、得られた樹脂のゴム粒子平均径が０．０５〜１μｍ、好ましくは０．１〜０．８μｍであれば光沢の高い樹脂が得られる。Ｆが３５を越えて１５０以下であれば粒子Ｂは４０〜９０％生成し、上記粒度分析装置でのゴム粒子平均径が０．５〜３μｍ、好ましくは１〜２．５μｍであれば、艶消し効果のある樹脂が得られる。本発明の方法では、例えば粒子Ｂを０．０１〜１％含有する光沢の高い樹脂を剪断効果の高い押出機により処理することによりさらに高い光沢の成形物が得られる樹脂にすることが可能であり、艶消し効果のある樹脂についても、１つの樹脂から用途によって適当な光沢に調整することができる。
【００３４】
例えば上記の方法で得られた樹脂を溶融状態で押出機に送入する。ここで使用する押出機はダルメージスクリューを有する１軸押出機であり、押出機入口からダルメージ部との間に水を添加する部分と、ダルメージ部と同時またはその直前部に添加した水を蒸発させる部分とを有する１軸押出機を用いる。添加する水の割合は、１時間あたり押出機が処理する樹脂量１００重量部に対して０〜１５重量部、好ましくは１〜１０重量部、より好ましくは１〜７重量部である。ダルメージ部より前の部分で水を添加し、蒸発させることによって樹脂温を下げ、ダルメージ部での樹脂にかかる剪断力を高めることができる。水の他に低沸点の有機溶媒を混合して使用しても良い。
【００３５】
本発明においてダルメージ部より前の部分で水を添加する部分を持たない場合はダルメージ部と同時または直前部で押出機のシリンダー温度を回収工程出口の樹脂温の０〜６０％低下、より高光沢の製品が得たい場合は１５〜６０％低下させることにより本発明の効果が得られる。但し大型の押出機の場合、樹脂温を低下させることは困難であるので好ましくない。
【００３６】
本発明においては分離回収工程での温度の変動の程度と、押し出し工程での樹脂にかかる剪断の程度によって、得られた樹脂の表面モルフォロジーが決められる。押し出し工程で樹脂にかかる剪断の程度は、ダルメージスクリューを有する１軸押出機では、下記式（数３）（数４）で示される剪断指標（Ｓ）を用いる。
【００３７】
【数３】
γ＝πＮＤ／Ｃ
Ｎ：１秒間あたりのスクリュー回転数（ｒｐｓ）
Ｄ：スクリュー径（ｍｍ）
Ｃ：押出機のシリンダーとダルメージ部との最も小さい部分の距離（ｍｍ）
【００３８】
【数４】
Ｓ＝（３５０−Ｔ_１ ）×０．０２×γ_ｍ ×（θ／６０）×Ｌ／１００
Ｔ_１ ：ダルメージ部入口の樹脂温（℃）
θ ：押出機中の樹脂の滞留時間 （ｓｅｃ）
Ｌ ：スクリュー有効長に対するダルメージ部の割合（％）
このＳとＢ_１ により粒子Ｂの変化率（Ｂ_Ｄ ）が決まる。粒子Ｂの変化率Ｂ_Ｄ は下記式（数５）により求められる。
【００３９】
【数５】
Ｂ_Ｄ ＝（Ｂ_１ −Ｂ_２ ）／Ｂ_１ ×１００
上記Ｂ_１ ・Ｓを用いて粒子Ｂの変化率Ｂ_Ｄ を考えると、例えばＳが８０以下ではＢ_Ｄは０〜４０％となり、Ｓが８０を越えるとＢ_Ｄは４０〜９５％となる。
また、Ｓの範囲は５〜３００、好ましくは１０〜２００、より好ましくは２０〜１５０である。
【００４０】
即ち、あるＢ_１ をもつ成形物１となるようなＡＢＳ樹脂を製造しておけば、Ｓを変えることにより様々なモルフォロジーの製品を得ることができる。
【００４１】
本発明の方法により得られた樹脂の成形物は衝撃強度等他の物性を低下することなく表面特性をコントロールできるため、電気機器やコンピューター等の産業分野の部品として幅広く有用であり、また化粧品容器や玩具・文房具等の成形物として特に有用である。
【００４２】
【実施例】
次に実施例により本発明を更に詳細に説明するが、本発明はこれらの実施例により限定されるものではない。性能評価は下記の基準で測定した。
（１）光沢測定
ＪＩＳＫ７１０５中の光沢度の測定（６０°鏡面光沢）の測定法に準じて１０ｍｍ×５０ｍｍの試験片３個について光沢を測定し、その平均値を求めた。
（２）衝撃強度の測定
衝撃強度は成形物を切り出し試験片とし、１ｚｏｄ衝撃試験法（ＪＩＳ−Ｋ７１１０）で行なった。
（３）耐熱温度の測定
ビカット軟化点はＡＳＴＭ Ｄ１５２５に準拠して、成形物から試験片を切り出したサンプルを用いて評価した。
（４）ゴム粒子形態の測定
ＴＥＭ（透過型電子顕微鏡）の超薄切片法により、ゴム粒子形状を測定した。
（５）ゴム粒子平均径の測定
成形物２の成形前のペレットを超薄切片法による電子顕微鏡写真を撮影し、写真中のゴム粒子５００〜７００個の短径及び長径をそれぞれ測定して、その平均値を粒子径とし、次式により体積平均径を求めた。
体積平均径＝ΣｎＤ^４／ΣｎＤ^３
（但しｎは粒子径Ｄμｍのゴムの個数である。）
参考例
スチレン７５重量部、アクリロニトリル２５重量部、エチルベンゼン１９重量部、ゴム状重合体（スチレン−ブタジエンブロック共重合体 溶液粘度１５ｃｔｓ：５％スチレン溶液 ２５℃）１０．５重量部、有機過酸化物［１，１−ビス（ｔ−ブチルパーオキシ）３，３，５−トリメチルシクロヘキサン］０．０４重量部、メルカプタン０．１重量部よりなる原料溶液を作成した。この原料を３段の攪拌式重合槽列反応器にて重合を行なった。１段目の槽から原料溶液を連続的に供給した。１段目の槽の反応温度９８℃、２段目の槽では１２０℃、３段目の槽では１３０℃とした。３段目の槽より重合液を予熱器と減圧室より成る分離回収工程に導いた。分離回収工程の出口での樹脂の平均温度（Ｔ_ａｖ）を２４０℃、温度変動率（Ｔ_ｄｅ）を４％、１時間あたりの変動回数（Ｎ）１０回として回収工程から出た樹脂の一部を射出成形した（成形物１）。得られた成形物の表面を電子顕微鏡で観察した。分離回収工程から出た樹脂を表１に示す押出機Ａにて、スクリュー回転数１．７ｒｐｓの条件でシリンダー温度を２４０℃として、水を添加することなく処理した後、射出成形を行った。結果を表２に示す。ダルメージ部入り口の温度（Ｔ_１ ）は２４０℃であった。分離回収工程出口の温度からダルメージ部入り口の温度の低下率（Ｄｅ）を（Ｔ_１ −Ｔ_０ ）／Ｔ_０ ×１００とするとＤｅは０％であった。成形物１の表面には粒子Ｂが５０％観察され、光沢は２５％であり、成形物２の表面には粒子Ｂが４７．５％、Ｂ_Ｄは５％、光沢は２７％となり、良好な艶消し性を有している。なお温度変動率及び１時間当たりの温度変動率は、予熱器のジャケットの熱媒の平均温度及び流量で調節した。なお本実験に使用したペレットは、３時間を１ロットとして混合して使用した。
【００４３】
実施例Ａ−１
回収工程を出た樹脂を参考例と同じ押出機に導入し、スクリューの回転数を３ｒｐｓ、水を１時間当たりの樹脂の押し出し量に対して２重量％添加し、シリンダーの温度を２１５℃とした。結果を表２に示す。Ｔ_１ は２１８℃でありＤｅは９．２％であった。Ｂ_Ｄは１３％、成形物２の光沢は３０％となり、参考例に比べ光沢が向上した。
【００４４】
実施例Ａ−２
スクリューの回転数を４．２ｒｐｓとした以外は実施例Ａ−１と同じとした。結果を表２に示す。Ｔ_１ は２２０℃でありＤｅは８．３％であった。Ｂ_Ｄは１７％、成形物２の光沢は３１％となり、参考例に比べ光沢が向上した。
【００４５】
実施例Ａ−３
スクリューの回転数を３．７ｒｐｓとし、水の添加量を５重量％とし、シリンダー温度を１８０℃とした以外は実施例Ａ−１と同じとした。結果を表２に示す。Ｔ_１ は１８５℃でありＤｅは２２．９％であった。Ｂ_Ｄは３８％、成形物２の光沢は３８．５％となり、さらに光沢が向上した。
【００４６】
実施例Ａ−４
スクリューの回転数を３．７ｒｐｓとし、水の添加量を１０重量％とした以外は実施例Ａ−１と同じとした。結果を表２に示す。Ｔ_１ は１３０℃でありＤｅは４５．８％であった。Ｂ_Ｄは７０％、成形物２の光沢は５０％となり、実施例Ａ−１より光沢が向上した。
【００４７】
実施例Ｂ−１
分離回収工程の出口での温度変動率（Ｔ_ｄｅ）を３％、１時間あたりの変動回数（Ｎ）１回として回収工程から出た樹脂の一部を射出成形した（成形物１）。分離回収工程から出た樹脂を表１に示す押出機Ａにて、スクリュー回転数４．７ｒｐｓ、押出機で水を添加することなく、シリンダーの温度を２２０℃として処理した後、射出成形を行った。結果を表２に示す。Ｔ_１は２３５℃であり、Ｄｅは２．１％であった。成形物１の表面には粒子Ｂが０．５％観察され、光沢は７３％であり、成形物２の表面には粒子Ｂが０．４％、Ｂ_Ｄは２０％、光沢は８１％となり、高い光沢を有する成形物が得られた。
【００４８】
実施例Ｂ−２
押出機での水の添加量を樹脂に対して５重量％添加する以外は実施例Ｂ−１と同じとした。結果を表２に示す。Ｔ_１は１８５℃であり、Ｄｅは２２．９％であった。Ｂ_Ｄは７０％、光沢は９３％となり実施例Ｂ−１より光沢が向上した。
【００４９】
実施例Ｃ−１
分離回収工程の出口での温度変動率（Ｔ_ｄｅ）を２５％、１時間あたりの変動回数（Ｎ）４回として回収工程から出た樹脂の一部を射出成形した（成形物１）。分離回収工程から出た樹脂を表１に示す押出機Ａにて、スクリュー回転数３．７ｒｐｓの条件でシリンダー温度を２２０℃として、水を添加することなく処理した後、射出成形を行った。結果を表２に示す。ダルメージ部入り口の温度Ｔ_１ は２３５℃であり、Ｄｅは２．１％であった。成形物１の表面には粒子Ｂが７５％観察され、光沢は２１％であり、成形物２の表面には粒子Ｂが６４％、Ｂ_Ｄは１６％、光沢は２５％となり、良好な艶消性を有する成形物が得られた。
【００５０】
実施例Ｃ−２
水の添加量を１０重量％とした以外は実施例Ｃ−１と同じとした。結果を表２に示す。Ｔ_１ は１３２℃でありＤｅは４５％であった。Ｂ_Ｄは７３％、成形物２の光沢は４２．８％となり、実施例Ｃ−１より光沢が向上した。
【００５１】
比較例Ｄ−１
分離回収工程の出口での温度の変動までを実施例Ｂ−１の条件と同じで製造した樹脂を表１に示す押出機に導入し、スクリュー回転数４．７ｒｐｓ、水を添加することなく処理した。結果を表３に示す。成形物２の光沢は７３．５％でほとんど光沢は向上しなかった。
【００５２】
比較例Ｄ−２
水の添加量を５重量％とした以外は比較例Ｄ−１と同じとした。結果を表３に示す。得られた成形物２の光沢は７３．５％でほとんど光沢は向上しなかった。
この様に１軸フルフライトスクリューでは剪断指数を変えても光沢はほとんど変化しない。
【００５３】
比較例Ｅ−１
ポリブタジエンラテックス２０重量部の存在下でスチレン７０％、アクリロニトリル３０％からなる単量体混合物８０重量部を乳化重合した。得られたグラフト共重合体は硫酸で凝固し、苛性ソーダで中和・洗浄・濾過・乾燥してＡＢＳ樹脂を得た。得られた樹脂を表１に示す押出機Ｃでシリンダー２３５℃、スクリュー回転数１．５ｒｐｓで溶融し、その溶融樹脂を押出機Ａに送入しスクリュー回転数３．３ｒｐｓで溶融し、樹脂に対して５重量％添加し、処理した後、射出成形を行った。結果を表−３に示す。成形物１の表面には粒子Ｂは観察されず、従ってＢ_Ｄもなかった。成形物２の光沢も７８％と変化しなかった。
【００５４】
比較例Ｅ−２
押出機での水の添加量を樹脂に対して１０重量％にする以外は比較例Ｅ−１と同じとした。結果を表３に示す。成形物１の光沢は７８％であり、成形物２の光沢も７８．５％とほとんど向上していない。乳化重合ＡＢＳでは剪断指標が異なる１軸押出機を用いても、光沢をコントロールする事は出来ない。
【００５５】
【表１】

【００５６】
【表２】

【００５７】
【表３】

【００５８】
【発明の効果】
本発明の方法により成形物の表面におけるゴム粒子モルフォロジーが自由に変えられるのでＡＢＳ樹脂の表面の特徴を極めて容易に発現させることができ、例えば光沢・艶消しを任意にコントロールできる。[0001]
[Industrial applications]
The present invention relates to a morphology of a molded article, and more particularly to a method for producing an ABS resin molded article which controls the morphology of the surface of the molded article.
[0002]
According to the present invention, since the rubber particle morphology on the surface of the molded product can be freely changed, the characteristics of the surface of the ABS resin can be very easily expressed, and for example, gloss / mat can be arbitrarily controlled.
[0003]
[Prior art]
Conventionally, various methods have been used to control the surface properties of ABS resins. For example, by using rubber particles having a large rubber particle diameter, the shape of the rubber particles on the surface (of course, the same applies to the internal particles) can be enlarged, or conversely, by using rubber particles having a small rubber particle diameter, Surface characteristics were controlled by reducing the shape of the rubber particles. That is, in the prior art, it is common to control the rubber particle diameter from the ABS resin manufacturing process, so that the influence of the rubber particle diameter control appears not only on the surface but also on the impact and rigidity of the molded product, and the physical properties are affected. It was a big problem in terms of balance. For example, when rubber particles having a large particle diameter are used to impart a matting property, the matting property of the surface is excellent, but on the other hand, there is a problem that the impact strength is reduced. In addition, when the rubber particle diameter is reduced to impart gloss to the surface, the gloss is excellent, but the impact strength is reduced, so that a large amount of the rubber component is required. As another method for controlling the surface morphology of the ABS resin, there is a method of specifying molding conditions at the molding stage. For example, it has been practiced to use high mold temperatures during injection molding to maintain high gloss. In this case, molding conditions are limited, the molding injection cycle is lengthened, and an important problem in productivity remains.
[0004]
Further, conventionally, in order to maintain the surface gloss at a specific value, it was necessary to strictly control in the polymerization step. In the present invention, not only the control in the production of the raw material resin but also the surface characteristics can be strictly controlled in the extrusion step.
[0005]
[Problems to be solved by the invention]
Accordingly, an object of the present invention is to provide a method for arbitrarily controlling the surface morphology of a molded article of an ABS resin while maintaining impact strength and the like.
[0006]
[Means for Solving the Problems]
In the present invention, the morphology (morphology of the rubber particles) of the rubber particles observed on the surface of the molded product is controlled by using a technical means completely different from the conventional one. That is, in the present invention, at least a styrene-based monomer and an acrylonitrile-based monomer, and a raw material containing a rubber-like polymer are supplied to the polymerization step, and a part or all of the monomer is polymerized to produce rubber-like polymer particles. After the step of polymerizing the polymer including (rubber particle) formation, the mixed solution containing the polymer, the unreacted monomer and / or the solvent is heated and introduced into the reduced pressure chamber simultaneously or after the heating, and the monomer and And / or a separation / recovery step of separating the solvent from the resin component. A molded product (molded product 1) obtained by injection-molding the resin that has gone through the separation / recovery process is formed of rubber particles observed on the surface of the molded product. Among them, the particles A have a ratio a / b of the major axis a to the minor axis b of 1.5 or less, and the particles B have a ratio a / b of the major axis a to the minor axis b of 5 or greater. It was not known at all that it was possible to control the amount of the particles A and B by extruding the resin with a single-screw extruder having a shearing effect after the separation and recovery step. The present inventors arbitrarily control the gloss of the surface of a molded article by an unconventional method of adjusting the proportion of rubber particles, particles A and B, of different forms observed near the surface of the molded article by an extruder. The inventors have found out what can be done, and have reached the present invention.
[0007]
That is, [I] a raw material containing at least a styrene-based monomer, an acrylonitrile-based monomer, and a rubbery polymer is supplied to a polymerization step, and a part or all of the monomer is polymerized to form rubber particles. After the step of polymerizing the polymer, the mixed solution containing the polymer, unreacted monomer and / or solvent is heated, and simultaneously or after heating, introduced into a reduced pressure chamber to convert the monomer and / or solvent with the resin component. A rubber particle present at a depth of 0.5 to 1.5 μm from the surface of a molded product (molded product 1) obtained by injection-molding a resin exiting the separation and recovery process, which has a separation and recovery process for separation, When observing the plane parallel to the surface of the molded product with an electron micrograph by the ultra-thin section method,
{Circle around (1)} particles A in which the ratio a / b of the major axis a to the minor axis b is 1.5 or less, and
{Circle around (2)} Particle B having a ratio a / b of major axis a to minor axis b of 5 or more
And the area of the particles A is at least 10% and the area of the particles B is 0% when the total area of the rubber particles observed in the electron micrograph by the ultra-thin section method is 100%. ABS resin which is 0.11 to 90%,
[II] After exiting the separation and recovery step, the surface of the obtained molded product (molded product 2) is subjected to shearing by a single screw extruder having a dalmage screw in the same manner as described above, that is, the surface of the molded product. When a parallel plane having a depth of from 0.5 to 1.5 μm is observed with an electron micrograph by an ultra-thin section method, and the area of the particles B is set to 100% of the ratio of the particles B observed in the molded article 1 described above. This is a method of controlling so as to be 0 to 95%. The present invention is characterized in that particles A and B are present on the surface of a molded product (molded product 1) obtained by injection-molding a resin that has gone through the separation and recovery step.
[0008]
(As a method for obtaining the molded article 1 in the present invention, the morphology of the resin obtained by polymerization is measured. Therefore, a sample valve is provided at the outlet of the separation and recovery step, the resin is taken out in a string form, and cooled in a water bath. Thus, a strand is obtained and cut to form a pellet, from which a molded article 1 is obtained by injection molding.)
That is, assuming that the total area of the observed rubber particles among the rubber particles existing at a depth of 0.5 to 1.5 μm from the surface of the molded article 1 is 100%, 10% or more is the area of the particle A, preferably 10 to 50%, more preferably 10 to 40%, and 0.01 to 90% occupy the area of the particles B, preferably 0.05 to 50%, more preferably 0.1 to 30%. It is characteristic. In the present invention, if the area of the particles A is less than 10% or the area of the particles B is less than 0.01%, the morphology of the rubber particles on the surface, which is the object of the present invention, cannot be controlled, and the gloss is locally low. Part occurs. On the other hand, if the content of the particles B exceeds 90%, a streak pattern is formed on the surface of the molded product even if the treatment is carried out by an extruder, which is not preferable.
[0009]
In the present invention, [I] a raw material containing at least a styrene-based monomer, an acrylonitrile-based monomer, and a rubbery polymer is supplied to a polymerization step, and a part or all of the monomer is polymerized to obtain rubber particles. After the step of polymerizing the polymer including formation, the mixture containing the polymer, unreacted monomer and / or solvent is heated, and simultaneously or after heating, introduced into a vacuum chamber to remove the monomer and / or solvent. A rubber having a separation / recovery step of separating from a resin component and having a depth of 0.5 to 1.5 μm from the surface of a molded article (molded article 1) obtained by injection-molding the resin exiting the separation / recovery step. When the particles are observed on an electron micrograph taken by an ultra-thin section method, a plane parallel to the surface of the molded product has at least two types of particles A and B, and is observed by an electron micrograph taken by an ultra-thin section method. Total area of rubber particles observed 100% the area of the particle A is at least 10% or more when the ABS resin is the area of the particle B is from 0.01 to 90 percent,
[II] After exiting the separation / recovery step, a part where water is added to the resin between the separation / recovery step outlet and the part where the dalmage is installed (Dalmage part) using a single screw extruder having a dalmage screw. And a molded product obtained by applying shearing by using an extruder provided at the same time as the entrance of the dalmage part or immediately in front of the same, at the part where the added water is evaporated. The surface of the molded article 2) was observed in the same manner as described above, that is, a parallel plane having a depth of 0.5 to 1.5 μm from the molded article surface was observed with an electron micrograph by an ultra-thin section method, and the area of the particles B was determined as described above. In this method, the ratio of particles B observed in the molded product 1 is controlled to be 0 to 95% when the ratio is 100%.
[0010]
At this time, the proportion of water to be added is 0 to 15 parts by weight, preferably 0.1 to 10 parts by weight, more preferably 0.5 to 7 parts by weight based on 100 parts by weight of the resin extruded per unit time. . If the amount of water exceeds 15 parts by weight, the processing capacity of the extruder is reduced, and the productivity is undesirably affected. Further, by adding and evaporating water immediately before the dalmage portion and lowering the resin temperature at the outlet of the separation / recovery step by 0 to 60% immediately before the dalmage portion, a sufficient shearing force is given at the dalmage portion. When water is not added, the temperature of the extruder cylinder is reduced by 0 to 60% of the resin temperature at the outlet of the recovery step at the portion where the dalmage screw is installed or immediately before the portion in the extruder. As in the case where is added, a sufficient shearing force is applied to the resin. However, when the resin temperature is lowered by the temperature of the cylinder, the size of the extruder is limited, and in the case of a large extruder, the resin temperature cannot be controlled by the cylinder temperature.
[0011]
In the present invention, it is preferable that the ratio L / D of the screw length (L) and the cylinder diameter (D) of the extruder is 10 to 50. It is more preferably 15 to 35, and still more preferably 25 to 30. In addition, a single screw extruder provided with a dull mage portion so that the dull mage portion is 5 to 40%, preferably 10 to 30% of the effective cylinder length is used. If the dalmage portion is less than 5% of the effective cylinder length, sufficient shear will not be applied, and if it exceeds 60%, excessive shear will be applied and the resin will deteriorate due to shear heat generation. The effective screw length in the present invention indicates the length of the screw excluding the ground portion at the root of the screw and the conical portion at the tip, and is usually expressed as L / D or D times as many as the above.
[0012]
The extruder in the present invention is one of the devices used for extrusion molding and compounding. The material is continuously heated, melted and kneaded between a portion called a cylinder and a rotary screw, and the material is die-kneaded. Extruded from the material, and formed into a shape or a pellet. The amount of shear varies depending on the shape of the rotary screw. In the present invention, a single screw extruder having a dalmage screw is particularly used.
[0013]
In addition, the dalmage screw in the present invention is a screw such that the resin is sheared between the cylinder and the high part that separates the groove, a seagull-shaped groove is dug in a cylindrical portion slightly lower than the flight. is there.
[0014]
The morphology of the surface of the molded product affects the surface characteristics of the molded product. Even if the average particle diameter of the rubber particles produced from the polymerization step is the same, if the area ratio of the particles B is small, the gloss of the surface of the molded product is improved. When the ratio of the area of B increases, the surface of the molded product becomes matt. In the present invention, not only the adjustment of the rubber particle diameter from the polymerization step, but also the characteristics of the molded product surface can be arbitrarily adjusted from the same raw material ABS resin by controlling the ratio of the area of the particles B by an extruder. The industrial benefits are very large.
[0015]
In the conventional method of controlling the gloss by adjusting the rubber particles of the raw material, the production process is very long. Particularly, when changing the grade from a matting resin to a high gloss resin, the ABS resin is used from the first step of the production. Over time, a product with a different gloss is necessarily produced. In a typical industrial plant, if the residence time of all processes is 4 hours, the above non-genuine product will be produced for about 4 to 12 hours. During this period, the products are not only half-finished but also vary in gloss, which greatly limits their use. Industrially, in order to produce a wide variety of grades in one plant, it is extremely important for the productivity of the plant that irregular products are generated at the time of grade exchange.
[0016]
On the other hand, in the method of the present invention, which is the last stage of the process, the process time is short, and a resin having a desired gloss can be obtained by easy adjustment.
[0017]
The ABS resin referred to in the present invention is a resin composed of a copolymer of a rubbery polymer, a styrene monomer, an acrylonitrile monomer and, if necessary, another monomer. Here, styrene-based monomers include styrene, α-alkylmonovinylidene aromatic monomers (for example, α-methylstyrene; α-ethylstyrene; α-methylvinyltoluene; α-methyldialkylstyrene; etc.), rings Substituted alkylstyrenes (eg, om- and p-vinyltoluene; o-ethylstyrene; p-ethylstyrene; 2,4-dimethylstyrene; p-tert-butylstyrene; etc.), ring-substituted halostyrenes (eg, o- Chlorostyrene; p-chlorostyrene; o-bromostyrene; 2,4-dichlorostyrene; etc.), ring-alkyl, ring-halo-substituted styrenes (eg, 2-chloro-4-methylstyrene; 2,6-dichlorostyrene; Etc.) One or a mixture of vinyl naphthalene and vinyl anthracene is used. Generally, alkyl substituents will have from 1 to 4 carbon atoms and include isopropyl and isobutyl groups. One or a mixture of the monovinylidene aromatic monomers is used. Examples of the acrylonitrile-based monomer include acrylonitrile, methacrylonitrile, ethacrylonitrile, fumaronitrile, and mixtures thereof.
[0018]
The rubbery polymer is not particularly limited as long as it shows a rubbery state at room temperature, but is preferably a polybutadiene such as conjugated 1,3-diene (for example, butadiene; isoprene; etc.) or styrene-butadiene. Examples of the polymer include EPDM (ethylene-propylene-diene methylene linkage).
[0019]
The other monomer in the present invention is not particularly limited as long as it is a monomer copolymerizable with styrene and acrylonitrile, but acrylates such as methyl methacrylate and maleimides such as N-phenylmaleimide and cyclohexylmaleimide. Is raised.
[0020]
The composition of the ABS resin is preferably 50 to 95 parts by weight of styrene, 5 to 50 parts by weight of acrylonitrile, 3 to 30 parts by weight of a butadiene polymer or a styrene-butadiene block copolymer in the resin. A preferred method for obtaining a resin having these compositions is obtained by polymerizing styrene and acrylonitrile using an organic peroxide as an initiator in the presence of a rubbery polymer. As the polymerization method, continuous bulk polymerization and solution polymerization are preferably used.
[0021]
The ABS-based resin used in the present invention is the above-mentioned ABS resin and a resin containing the ABS resin as a component. The resin containing the ABS resin as a component is an ABS resin and other resins, for example, polycarbonate, polyphenylene ether. , Polypropylene, polystyrene, a mixture of acrylonitrile-styrene copolymer resin and the like, a mixture of an ABS resin and a flame retardant, and a glass filler, a mixture of talc and the like, as long as the resin containing the ABS resin as a component is not particularly limited. Absent.
[0022]
The molded article of the ABS resin used in the present invention is a molded article obtained by molding the ABS resin, and as a mechanical part, a stationery article, a toy by utilizing the mechanical and chemical characteristics of the ABS resin. Etc. are themselves used as final products. As the molding process, a conventionally known molding method of a resin is used, and examples thereof include injection molding and extrusion molding. Preferably, it is an injection molding method. Preferred injection molding conditions are as follows: the cylinder temperature of the molding machine is 170 to 280C, preferably 180 to 260C, more preferably 200 to 250C, and the mold temperature is 30 to 90C.
[0023]
The region that defines the morphology of interest in the present invention has a depth of 0.5 to 1.5 μm from the surface because the rubber particles present in the depth in this range are formed into a specific morphology that has not existed in the past, so that molding is performed. Based on the finding that the surface properties of an object can be controlled. The value of 0.5 to 1.5 μ near the surface is also based on the discovery that the state of existence of the rubber particles between these depths is almost constant without being dependent on the depth. . That is, when the depth is less than 0.5 μm, the morphology of the rubber particles varies greatly. When the depth exceeds 1.5 μm, the existence state changes depending on the depth. Not suitable for identifying.
[0024]
In the present invention, the form of the rubber particles is measured on a parallel surface of the surface of the molded product. This parallel cross section is obtained by cutting a molded product into an ultrathin section using a microtome parallel to the surface of the molded product. At this time, the thickness of each sample cut out by a microtome is set to 0.05 μm, and the sample is cut out sequentially from the surface, and the morphology is measured using the 11th to 30th samples.
The particle A in the present invention is defined as a particle having a ratio of a to b of 1.5 or less, where a / b is a length of a μm and b is a short diameter in an electron micrograph of the sample. A is defined. B is a particle having a / b of 5 or more.
[0025]
The major axis a referred to in the present invention represents the maximum length of the distance between two points on the circumference of the rubber particle observed in an electron micrograph by an ultra-thin section method, and the minor axis b is a / a in the major axis a. 2 shows the length of the rubber particle perpendicular to the major axis a at point 2. Under these constraints, when calculating the area of the particles A and B, the total area is 1000 μm.²  As described above, the size of the visual field to be observed with the electron microscope is determined. Although the number is not particularly limited, the field of view of the above-mentioned electron microscope is the size of a field of view containing 1000 or more rubber particles.
[0026]
In the present invention, when a parallel plane having a depth of 0.5 to 1.5 μm from the surface of the molded article 1 is observed by an electron microscope using an ultra-thin section method, a resin having particles A and B is separated and recovered. Shearing is performed by a single screw extruder in the molten state after the process. When the resin thus obtained was formed (molded product 2) and the surface of the molded product was observed with an electron micrograph in the same manner as in molded product 1, the area ratio of particles B observed in molded product 1 was 100%. Then, by setting the area ratio of the particles B in the molded product 2 to 0 to 95%, the surface characteristics of the molded product can be arbitrarily controlled.
[0027]
For example, the morphology of the molded product 2 is determined by the ratio of the area of the particles B in the molded product 1 (B₁  ) And the degree of shearing of the extruder, the ratio of the area of the particles B in the molded product 2 (B₂  ) Is determined by the degree of change of the ratio of the area of the particles B to the area (change rate of the particles B). That is, the degree of shear of the extruder and B₁  The change rate of the particles B can be adjusted by the combination of
[0028]
For example, the ratio of the area of the particles B observed in the molded product 1 is generated by a change in the recovery temperature in the separation and recovery step of the ABS resin manufacturing step by the solution or bulk polymerization method. For example, in the ABS resin production process by the bulk polymerization method, the resin average temperature (T_AV) Is in the range of 170 to 260 ° C., and the resin temperature at the outlet of the recovery is changed._AVOf the temperature at the recovery outlet with respect to_de) And the number of temperature fluctuations per hour (N_CTThe particles B observed on the surface of the molded product after the molding process are generated by adjusting the product of ()). T_deAnd N_CTAs the product of the rubber particles increases, the number of rubber particles that eventually become the particles B in the molded product can be increased.
[0029]
In the present invention, the average value of the recovery temperature (T_AV) Is calculated by the following equation (Equation 1).
[0030]
(Equation 1)

The temperature fluctuation rate (T_de: Temperature fluctuation rate per hour) is calculated by the following equation (Equation 2).
[0031]
(Equation 2)
Temperature fluctuation rate (T_de= ((T_max  −T_min  ) / T_AV) × 100
(However, T_max  Is the maximum recovery temperature per hour, T_min  Is the minimum temperature)
In addition, the number of temperature fluctuations per hour is represented by the number of temperature fluctuations per hour (N_CT) (However, fluctuations within a temperature fluctuation rate of 0.5% are neglected), and refers to the number of times that the differential value of the temperature changes positive or negative with respect to time.
[0032]
In the present invention, the average value T of the recovery temperature_AV, Temperature fluctuation rate T_de, And the number of temperature fluctuations per hour N_CTIs operated while keeping the average value of the recovery temperature for 3 hours or more constant, and is calculated from the measured values in that section.
[0033]
T above_deAnd N_CTBy adjusting the product (F), particles that can become particles B on the surface of the molded product after the molding process are generated. In the present invention, those having a value of F of 0.5 to 150 can be used, and particularly, a mixture of two or more resins having different values of F gives a preferable result. At this time, an average value obtained from the mixing ratio and the F value and falling within the range of 0.5 to 150 can be used. For example, when F is 0.5 to 15, particles B are formed in an amount of 0.01 to 1%, and when the average particle diameter of rubber particles of the obtained resin is 0.05 to 1 μm, preferably 0.1 to 0.8 μm, gloss Resin with a high viscosity. If F is more than 35 and not more than 150, particles B are formed in an amount of 40 to 90%. A resin having an erasing effect can be obtained. In the method of the present invention, for example, a resin having a higher gloss can be obtained by treating a high-gloss resin containing 0.01 to 1% of the particles B with an extruder having a high shearing effect. Also, a resin having a matting effect can be adjusted to an appropriate gloss from one resin depending on the application.
[0034]
For example, the resin obtained by the above method is fed into an extruder in a molten state. The extruder used here is a single-screw extruder having a dalmage screw. The portion where water is added from the extruder inlet to the dalmage portion, and the water added simultaneously with or immediately before the dalmage portion are evaporated. And a single-screw extruder having a part to be extruded. The proportion of water to be added is 0 to 15 parts by weight, preferably 1 to 10 parts by weight, more preferably 1 to 7 parts by weight, per 100 parts by weight of the resin processed by the extruder per hour. By adding and evaporating water in a portion before the damaging portion, the temperature of the resin can be lowered, and the shearing force applied to the resin in the damaging portion can be increased. A low boiling organic solvent may be used in combination with water.
[0035]
In the present invention, in the case where there is no portion to which water is added in the portion before the dalmage portion, the cylinder temperature of the extruder is reduced at the same time or immediately before the dalmage portion by 0 to 60% of the resin temperature at the outlet of the recovery step, and the gloss is higher. If it is desired to obtain the product of the present invention, the effect of the present invention can be obtained by reducing the content by 15 to 60%. However, in the case of a large extruder, it is difficult to lower the resin temperature, which is not preferable.
[0036]
In the present invention, the surface morphology of the obtained resin is determined by the degree of temperature fluctuation in the separation and recovery step and the degree of shear applied to the resin in the extrusion step. The degree of shear applied to the resin in the extrusion step uses a shear index (S) represented by the following equations (Equation 3) and (Equation 4) in a single-screw extruder having a dalmage screw.
[0037]
(Equation 3)
γ = πND / C
N: Screw rotation speed per second (rps)
D: Screw diameter (mm)
C: Distance (mm) of the smallest part between the cylinder of the extruder and the dalmage part
[0038]
(Equation 4)
S = (350−T₁  ) × 0.02 × γ_m  × (θ / 60) × L / 100
T₁  : Resin temperature at inlet of dalmage part (℃)
θ: residence time of the resin in the extruder (sec)
L: Ratio of dal mage portion to effective screw length (%)
This S and B₁  The change rate of particles B (B_D  ) Is decided. Change rate B of particle B_D  Is determined by the following equation (Equation 5).
[0039]
(Equation 5)
B_D  = (B₁  -B₂  ) / B₁  × 100
B above₁  ・ Change rate B of particle B using S_D  Is considered, for example, if S is 80 or less, B_DIs 0-40%, and when S exceeds 80, B_DIs 40 to 95%.
Further, the range of S is 5 to 300, preferably 10 to 200, and more preferably 20 to 150.
[0040]
That is, a certain B₁  If an ABS resin is manufactured so as to be a molded article 1 having the following, products of various morphologies can be obtained by changing S.
[0041]
Since the resin molded product obtained by the method of the present invention can control surface characteristics without deteriorating other physical properties such as impact strength, it is widely useful as a component in industrial fields such as electric equipment and computers, and a cosmetic container. It is particularly useful as a molded product such as toys and stationery.
[0042]
【Example】
Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The performance evaluation was measured according to the following criteria.
(1) Gloss measurement
Gloss was measured for three test pieces of 10 mm × 50 mm in accordance with the measuring method of glossiness (60 ° specular gloss) in JISK7105, and the average value was obtained.
(2) Measurement of impact strength
The impact strength was determined by cutting a molded product into a test piece and subjecting it to a 1-zod impact test method (JIS-K7110).
(3) Measurement of heat resistance temperature
The Vicat softening point was evaluated using a sample obtained by cutting a test piece from a molded product in accordance with ASTM D1525.
(4) Measurement of rubber particle morphology
The rubber particle shape was measured by an ultra-thin section method using a TEM (transmission electron microscope).
(5) Measurement of rubber particle average diameter
An electron micrograph was taken of the pellet before molding of the molded article 2 by an ultra-thin section method, and the minor and major diameters of 500 to 700 rubber particles in the photograph were measured, and the average value was taken as the particle diameter. The volume average diameter was determined by the formula.
Volume average diameter = ΣnD⁴/ ΣnD³
(However, n is the number of rubber having a particle diameter of D μm.)
Reference example
75 parts by weight of styrene, 25 parts by weight of acrylonitrile, 19 parts by weight of ethylbenzene, 10.5 parts by weight of a rubbery polymer (styrene-butadiene block copolymer solution viscosity 15 cts: 5% styrene solution at 25 ° C.), 10.5 parts by weight, organic peroxide [1 , 1-bis (t-butylperoxy) 3,3,5-trimethylcyclohexane] and a raw material solution comprising 0.04 parts by weight of mercaptan. This raw material was polymerized in a three-stage stirred polymerization tank array reactor. The raw material solution was continuously supplied from the first tank. The reaction temperature in the first tank was 98 ° C, the temperature in the second tank was 120 ° C, and the reaction temperature in the third tank was 130 ° C. From the third tank, the polymerization liquid was led to a separation and recovery step comprising a preheater and a decompression chamber. Average temperature of resin at outlet of separation and recovery process (T_av) At 240 ° C. and temperature fluctuation rate (T_de) Was changed to 4% and the number of changes per hour (N) was set to 10 to injection-mold a part of the resin discharged from the recovery step (molded product 1). The surface of the obtained molded product was observed with an electron microscope. The resin discharged from the separation / recovery step was treated with an extruder A shown in Table 1 at a screw rotation speed of 1.7 rps and a cylinder temperature of 240 ° C. without adding water, followed by injection molding. Table 2 shows the results. Temperature at the entrance of the dalmage section (T₁  ) Was 240 ° C. The rate of decrease (De) in temperature at the entrance of the dalmage section from the temperature at the exit of the separation and recovery process is (T₁  −T₀  ) / T₀  Assuming × 100, De was 0%. 50% of the particles B were observed on the surface of the molded product 1 and the gloss was 25%, and 47.5% of the particles B and B were observed on the surface of the molded product 2._DIs 5% and the gloss is 27%, and has a good matting property. The temperature fluctuation rate and the temperature fluctuation rate per hour were adjusted by the average temperature and the flow rate of the heating medium in the jacket of the preheater. Note that the pellets used in this experiment were mixed and used for three hours as one lot.
[0043]
Example A-1
The resin that exited the recovery step was introduced into the same extruder as the reference example, the screw rotation speed was 3 rps, water was added at 2% by weight based on the resin extrusion amount per hour, and the cylinder temperature was 215 ° C. did. Table 2 shows the results. T₁  Was 218 ° C. and De was 9.2%. B_DWas 13%, and the gloss of the molded product 2 was 30%, which was higher than that of the reference example.
[0044]
Example A-2
It was the same as Example A-1 except that the screw rotation speed was 4.2 rps. Table 2 shows the results. T₁  Was 220 ° C. and De was 8.3%. B_DWas 17% and the gloss of the molded product 2 was 31%, which was higher than that of the reference example.
[0045]
Example A-3
Example A-1 was the same as Example A-1, except that the screw rotation speed was 3.7 rps, the amount of water added was 5% by weight, and the cylinder temperature was 180 ° C. Table 2 shows the results. T₁  Was 185 ° C. and De was 22.9%. B_DWas 38%, and the gloss of molded article 2 was 38.5%, further improving the gloss.
[0046]
Example A-4
Example A-1 was the same as Example A-1, except that the screw rotation speed was 3.7 rps and the amount of water added was 10% by weight. Table 2 shows the results. T₁  Was 130 ° C. and De was 45.8%. B_DWas 70%, and the gloss of molded product 2 was 50%, which was higher than that of Example A-1.
[0047]
Example B-1
Temperature fluctuation rate at outlet of separation and recovery process (T_de) Was 3%, and the number of changes per hour (N) was one, and a part of the resin discharged from the recovery step was injection-molded (molded product 1). The resin discharged from the separation / recovery step was processed in an extruder A shown in Table 1 at a screw rotation speed of 4.7 rps, without adding water with an extruder, at a cylinder temperature of 220 ° C., followed by injection molding. Was. Table 2 shows the results. T₁Was 235 ° C. and De was 2.1%. 0.5% of the particles B were observed on the surface of the molded article 1 and the gloss was 73%, and 0.4% of the particles B and B were observed on the surface of the molded article 2._DWas 20% and gloss was 81%, and a molded article having high gloss was obtained.
[0048]
Example B-2
Example B-1 was the same as Example B-1, except that the amount of water added in the extruder was 5% by weight relative to the resin. Table 2 shows the results. T₁Was 185 ° C. and De was 22.9%. B_DWas 70% and gloss was 93%, which was higher than that of Example B-1.
[0049]
Example C-1
Temperature fluctuation rate at outlet of separation and recovery process (T_de) Was 25% and the number of fluctuations per hour (N) was 4 times, and a part of the resin discharged from the recovery step was injection-molded (molded product 1). The resin discharged from the separation / recovery step was treated with an extruder A shown in Table 1 at a screw rotation speed of 3.7 rps at a cylinder temperature of 220 ° C. without adding water, followed by injection molding. Table 2 shows the results. Temperature T at the entrance to the dalmage₁  Was 235 ° C. and De was 2.1%. 75% of the particles B were observed on the surface of the molded article 1 and the gloss was 21%, and 64% of the particles B and B were observed on the surface of the molded article 2._DWas 16% and gloss was 25%, and a molded product having good matte properties was obtained.
[0050]
Example C-2
It was the same as Example C-1 except that the amount of water added was 10% by weight. Table 2 shows the results. T₁  Was 132 ° C. and De was 45%. B_DWas 73%, and the gloss of molded product 2 was 42.8%, which was higher than that of Example C-1.
[0051]
Comparative Example D-1
The resin produced under the same conditions as in Example B-1 up to the temperature fluctuation at the outlet of the separation and recovery step was introduced into the extruder shown in Table 1, and the screw was rotated at 4.7 rps and treated without adding water. did. Table 3 shows the results. The gloss of the molded product 2 was 73.5%, and the gloss was hardly improved.
[0052]
Comparative Example D-2
It was the same as Comparative Example D-1 except that the amount of water added was 5% by weight. Table 3 shows the results. The gloss of the obtained molded product 2 was 73.5%, and the gloss was hardly improved.
Thus, in the case of a single-shaft full flight screw, the gloss hardly changes even if the shear index is changed.
[0053]
Comparative Example E-1
In the presence of 20 parts by weight of polybutadiene latex, 80 parts by weight of a monomer mixture comprising 70% of styrene and 30% of acrylonitrile were emulsion-polymerized. The obtained graft copolymer was coagulated with sulfuric acid, neutralized with caustic soda, washed, filtered and dried to obtain an ABS resin. The obtained resin was melted by an extruder C shown in Table 1 at a cylinder 235 ° C. and a screw rotation speed of 1.5 rps, and the molten resin was fed into an extruder A and melted at a screw rotation speed of 3.3 rps. After adding 5% by weight and treating, injection molding was performed. Table 3 shows the results. No particles B were observed on the surface of the molded article 1,_DThere was no. The gloss of the molded product 2 was also unchanged at 78%.
[0054]
Comparative Example E-2
It was the same as Comparative Example E-1, except that the amount of water added in the extruder was 10% by weight based on the resin. Table 3 shows the results. The gloss of the molded product 1 is 78%, and the gloss of the molded product 2 is 78.5%, which is almost not improved. In emulsion polymerization ABS, gloss cannot be controlled even when a single screw extruder having a different shear index is used.
[0055]
[Table 1]

[0056]
[Table 2]

[0057]
[Table 3]

[0058]
【The invention's effect】
Since the rubber particle morphology on the surface of the molded article can be freely changed by the method of the present invention, the characteristics of the surface of the ABS resin can be very easily expressed, and for example, gloss / mat can be arbitrarily controlled.

Claims (6)

[I] A raw material containing at least a styrene-based monomer, an acrylonitrile-based monomer, and a rubber-like polymer is supplied to a polymerization step, and a part or all of the monomer is polymerized to obtain rubber-like polymer particles ( After the step of polymerizing the polymer including the formation of the rubber particles), the mixed solution containing the polymer, the unreacted monomer and / or the solvent is heated and introduced into the reduced pressure chamber simultaneously or after heating, and the monomer and / or Alternatively, it has a separation / recovery step of separating the solvent from the resin component, and has a depth of 0.5 to 1.5 μm from the surface of a molded product (molded product 1) obtained by injection-molding the resin exiting the separation / recovery process. When observing the rubber particles that are present in the electron micrograph by the ultra-thin section method, the plane parallel to the surface of the molded product,
(1) Particle A having a ratio a / b of major axis a and minor axis b of 1.5 or less, and (2) Particle B having a ratio a / b of major axis a and minor axis b of 5 or greater.
And the area of the particles A is at least 10% and the area of the particles B is 0% when the total area of the rubber particles observed in the electron micrograph by the ultra-thin section method is 100%. ABS resin that is 0.11 to 90%
[II] After exiting the separation and recovery step, the surface of the obtained molded product (molded product 2) is subjected to shearing by a single screw extruder having a dalmage screw in the same manner as described above, that is, the surface of the molded product. When a parallel plane having a depth of from 0.5 to 1.5 μm is observed with an electron micrograph by an ultra-thin section method, and the area of the particles B is set to 100% of the ratio of the particles B observed in the molded article 1 described above. A method for producing an ABS resin having various surface morphologies, characterized in that the resin is controlled to be 0 to 95%. [I] A raw material containing at least a styrene-based monomer, an acrylonitrile-based monomer, and a rubbery polymer is supplied to a polymerization step, and a part or all of the monomer is polymerized to obtain a polymer containing rubber particles. After the step of polymerizing the union, the mixed solution containing the polymer, the unreacted monomer and / or the solvent is heated, and simultaneously or after heating, introduced into a vacuum chamber to separate the monomer and / or the solvent from the resin component. A rubber particle existing at a depth of 0.5 to 1.5 μm from the surface of a molded product (molded product 1) obtained by injection-molding a resin exiting the separation / collection process is formed. When observing a plane parallel to the object surface with an electron micrograph by ultra-thin section method,
(1) Particle A having a ratio a / b of major axis a and minor axis b of 1.5 or less, and (2) Particle B having a ratio a / b of major axis a and minor axis b of 5 or greater.
And the area of the particles A is at least 10% and the area of the particles B is 0% when the total area of the rubber particles observed in the electron micrograph by the ultra-thin section method is 100%. ABS resin that is 0.11 to 90%
[II] A single screw extruder having a dalmage screw after exiting the separation and recovery step, wherein a part for adding water to the resin is provided between the separation and recovery step outlet and the part where the dalmage screw is installed. By having a portion for evaporating the added water, and a portion for evaporating the added water, by applying shear using an extruder provided at the same time as or immediately in front of the portion where the dalmage screw is installed, Observe the surface of the obtained molded article (molded article 2) in the same manner as above, that is, observe a parallel plane having a depth of 0.5 to 1.5 μm from the molded article surface with an electron micrograph by an ultra-thin section method, A method for producing an ABS resin having various surface morphologies, wherein the area of the particles B is controlled to be 0 to 95% when the ratio of the particles B observed in the molded article 1 is 100%. 3. The method for producing an ABS resin according to claim 2, wherein the proportion of water to be added is 0 to 15 parts by weight per 100 parts by weight of the resin extruded per unit time. 2. The method according to claim 1, wherein the temperature of the extruder cylinder is reduced to 0 to 60% of the resin temperature at the outlet of the recovery step at the portion where the dalmage screw is installed in the extruder or immediately before the portion. A method for producing an ABS resin. 3. The method according to claim 2, wherein the temperature of the extruder cylinder is reduced to 0 to 60% of the resin temperature at the outlet of the recovery step at a portion where the dalmage screw is installed in the extruder or immediately before the portion. A method for producing an ABS resin. 3. The method according to claim 1 , wherein the ratio L / D of the screw length (L) to the cylinder diameter (D) of the extruder is 10 to 50, and the dalmage portion is 5 to 40% of the effective screw length. A method for producing an ABS resin, comprising using a single screw extruder.