JP3755224B2 - Manufacturing method of resin pellets - Google Patents

Description

ここで、Ｑ（ｋｇ／ｈｒ）はペレット供給速度を示す。
【０００８】
【発明の実施の形態】
以下発明の実施の形態を図面を用いて説明する。
【０００９】
図１（Ａ）は本発明の方法に使用される装置の一例の概略図である。カッティングされて所望でない大きさのペレットを含むペレットは、ディストリビューター１によって篩の幅方向に拡散される。振動篩には篩面多孔部２が設けられている。振動篩はモーターなどによって駆動する振動手段６によって振動される。所望の大きさを有する樹脂ペレットは、篩面多孔部２の孔から篩面下方に落下し、製品ペレット排出口３から装置外に排出される。所望の大きさを有しない樹脂ペレットは、篩面多孔部および篩面無孔部を通過し、規格外ペレット排出口４から装置外へ排出される。
【００１０】
本発明で使用する篩面多孔部は、図１（Ｂ）に示すように定義される、多孔部の長さＬ（ペレット流れ方向）および幅Ｗの関係が０．５≦Ｌ／Ｗ≦１．５が好ましく、特に好ましくは０．７≦Ｌ／Ｗ≦１．２である。Ｌ／Ｗが０．５より小さい場合、多孔部での滞留時間が短くなり、規格外ペレット排出口へ製品ペレットが混入してしまい、製品ペレット収率が低下するため好ましくない。また、Ｌ／Ｗが１．５より大きい場合は多孔部での滞留時間が長くなるため、長物などの規格外ペレットが混入してしまうため好ましくない。
【００１１】
本発明におけるペレット供給量と篩寸法の関係は、（１）式で定義されるＲの値が０．３≦Ｒ≦２の範囲にあることが好ましい。
【００１２】
【数３】

Ｒの値が２．０より大きい場合、ペレット供給量に対して開孔面積が大きいため、一旦分別された長物などの規格外ペレットが多孔部から落下し、製品ペレット中に混入するために好ましくない。一方、Ｒの値が０．３より小さい場合、ペレット供給量に対して開孔面積が小さいために処理能力が不足し、製品ペレットが規格外ペレット排出口から排出され、製品ペレットの収率が低下するため好ましくない。
【００１３】
本発明に使用するディストリビューター１は、ペレットを篩面の幅方向に広く分散させることを目的としている。
【００１４】
本発明における振動篩の振動数ν（ｒｐｍ）は、１０００≦ν≦１７００が好ましく、さらに好ましくは１１００≦ν≦１４００である。振動数νが１０００ｖｐｍより低いと分別が十分に行われず、ペレットの処理能力が落ちてしまうため好ましくない。また、１７００ｖｐｍより高いとペレットが篩面を跳ね上がり、処理能力が著しく低下するため好ましくない。
【００１５】
振幅ａ（ｍｍ）は１≦ａ≦５が好ましい。１ｍｍより小さい振幅では分別が十分に行われず、ペレットの処理能力が落ちてしまうため好ましくない。また、５ｍｍより大きい振動数ではペレットが篩面を跳ね上がり、処理能力が著しく低下するため好ましくない。
【００１６】
本発明に使用される振動篩は水平設置で使用できるが、１０°程度までの後方傾斜あるいは前方傾斜をしていても本発明の効果は何ら問題なく得ることができる。
【００１７】
本発明に使用される振動手段６は、振動モーターあるいはその他いかなるものを使用してもよい。また、振動源が篩面に与える運動形態は、ペレット流れ方向成分と鉛直方向成分とを合わせた成分となるが、その結果得られる運動形態は限定されることはなく、例えば、楕円型であっても直線型であってもよい。
【００１８】
本発明における篩面へのペレット供給方法は、バッチ式、連続式のいずれでも有効である。
【００１９】
【実施例】
次に実施例および比較例により本発明を説明する。実施例および比較例に示す物性等は以下のように測定した。
・規格外ペレット混入率
内径２．５ｍｍのガット状態で反応器から排出したナイロン６６樹脂を、カッターを用いて３．９ｍｍ間隔でカッティングすることにより、得られた円筒形状の正常寸法の製品ペレット１９００ｋｇに、内径または円筒の高さが、正常寸法を上回る規格外でかつ識別のために黒く着色したペレット１００ｋｇ（全体の５重量％）を添加した混合ペレットを、２４００、６０００、７５００ｋｇ／ｈｒのペレット供給速度で、所定の条件の振動篩による処理を実施した。
【００２０】
製品ペレット排出口から得られた製品および規格外ペレットの総量Ａ（ｋｇ）を測定した後、規格外ペレットを選別し、（２）式に示す式で総量Ａ中の規格外ペレット混入率Ｂ（％）を算出した。
【００２１】
【数４】

なお、規格外ペレット混入率１．０％以下が成形特性に影響しない良好なレベルとした。
【００２２】
・製品ペレット回収率
（３）式に示す式により、初期製品（規格内）ペレット１９００ｋｇの回収率ｒ（％）を算出した。
【００２３】
【数５】

・射出成形の可塑化時間の３σ
振動篩により処理したペレットを日精樹脂工業（株）ＰＳ−６０型射出成形機を用い、シリンダー温度２８５℃、可塑化ストロークを０〜１０cm、背圧０．９８ＭＰａの条件で空打ちし、連続１００ショットの可塑化時間を測定し、標準偏差σを求め、さらに３を乗じて３σとした。なお、この値３σが小さいほど、成形安定性が優れていると言える。
【００２４】
・振動篩の篩面および多孔板部分のサイズ
振動篩装置は、篩面の幅Ｗが１３０ｃｍと９０ｃｍの２種類を用いた。篩面には、必要な長さＬだけ多数の孔を規則的に開け、残りの部分を孔のない部分とした篩面用の金属プレートを使用した。
【００２５】
実施例および比較例について、製品ペレット排出口からの総量Ａ（ｋｇ）、規格外ペレット混入率Ｂ（％）、製品ペレット回収率ｒ（％）、および可塑化時間の平均値と３σの測定結果を表１にまとめた。
【００２６】
実施例１
多孔部の長さＬが１００ｃｍ、幅Ｗが１３０ｃｍの篩面を用い、ペレット供給速度Ｑを６０００ｋｇ／ｈｒにして分別処理を行った。この際、ペレット供給部にはディストリビュータを設置し、振動数は１３００ｖｐｍ、振幅は３．０ｍｍ、多孔部の孔径は４．７ｍｍ、多孔部中の孔面積占有率は２８．８％で実施した。Ｌ／Ｗが０．７７、Ｒが０．６２と適正であったため、Ｂ（％）が低く可塑化時間の３σが小さい高品質のペレットが得られ、製品ペレット回収率ｒ（％）も高くなった。
【００２７】
【表１】

【００２８】
実施例２
多孔部の長さＬが１５０ｃｍである以外は実施例１と同一条件で分別処理を行った。Ｌ／Ｗが１．１５、Ｒが１．１５と適正であったため、Ｂ（％）が低く可塑化時間の３σが小さい高品質のペレットが得られ、製品ペレット回収率ｒ（％）も高くなった。
【００２９】
実施例３
多孔部の長さＬが８０ｃｍ、幅Ｗが９０ｃｍの篩面を用い、ペレット供給速度６０００ｋｇ／ｈｒで篩分け処理を行った。Ｌ／Ｗが０．８９、Ｒが０．３５と適正であったため、Ｂ（％）が低く可塑化時間の３σが小さい高品質のペレットが得られ、製品ペレット回収率ｒ（％）も高くなった。
【００３０】
比較例１
多孔部の長さＬが２１０ｃｍである以外は実施例１と同一条件で篩分け処理を行った。Ｌ／Ｗが１．６２と大きすぎるためにＢ（％）が高くなり、可塑化時間の３σが大きくなった。
【００３１】
比較例２
多孔部の長さＬが５０ｃｍである以外は実施例１と同一条件で篩分け処理を行った。Ｌ／Ｗが０．３８と小さすぎるために、製品ペレット回収率ｒ（％）が低くなった。
【００３２】
比較例３
多孔部の長さＬが２１０ｃｍである以外は実施例３と同一条件で篩分け処理を行った。Ｌ／Ｗが２．３３と大きすぎるためにＢ（％）が高くなり、可塑化時間の３σが大きくなった。
【００３３】
比較例４
ペレット供給速度Ｑが７５００ｋｇ／ｈｒである以外は実施例３と同一条件で篩分け処理を行った。Ｒが０．２８と小さすぎるために、製品ペレット回収率ｒ（％）が低くなった。
【００３４】
比較例５
ペレット供給速度Ｑが２４００ｋｇ／ｈｒである以外は実施例２と同一条件で篩分け処理を行った。Ｒが２．３４と大きすぎるためにＢ（％）が高くなり、可塑化時間の３σが大きくなった。
【００３５】
比較例６
ディストリビュータを設置しないこと以外は実施例１と同一条件で篩分け処理を行った。篩面が有効に活用されないため、製品ペレット回収率ｒ（％）が低くなった。
【００３６】
【発明の効果】
ペレット化した熱可塑性樹脂を、本発明の振動篩による分別を行うことにより、異常形状ペレットを除去した高品質かつ成形安定性に優れたポリマーペレットを、高い収率で得ることができる。
【図面の簡単な説明】
【図１】（Ａ）は本発明の方法で使用した装置の斜視概念図である。（Ｂ）は図１（Ａ）に設けられた篩面多孔部の説明図である。
【符号の説明】
１．ディストリビューター
２．篩面多孔部
３．製品ペレット排出口
４．規格外ペレット排出口
５．篩面無孔部
６．振動手段[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing resin pellets, and more particularly, to a process of separating the shape of a thermoplastic resin pellet cut after being discharged from a reactor using a vibrating sieve.
[0002]
[Prior art]
The resin is generally discharged from the reactor and then pelletized by cutting in a molten or solidified state. At this time, abnormally shaped products such as long, thick, and continuous pellets (fused with multiple pellets) May be mixed. In many cases, a vibration sieve device is used as a conventional technique for separating abnormally shaped products. As a vibration sieve device for separating such particles, a horizontal installation type, an inclination type, a circular motion type are used. The electromagnetic type is known.
[0003]
For example, in the separation method described in JP-A-5-185037, a spherical powder and a non-spherical powder are given to a slanted surface by applying a periodic oblique upward vibration, and a difference in friction coefficient with the slanted surface. Proposes a way to separate the body. However, this method cannot separate continuously supplied resin pellets, which is not preferable as a method for producing a thermoplastic resin.
[0004]
In the separation method described in Japanese Patent Application Laid-Open No. 61-287486, the multistage diaphragms are supplied in a single layer with the angles of the multistage diaphragms gradually increased or decreased in a state where the multistage inclined diaphragms are partially overlapped. Proposed a method to increase the separation accuracy. However, even with this method, the continuously supplied resin pellets cannot be separated, which is not preferable as a method for producing a thermoplastic resin.
[0005]
Further, in the separation method described in Japanese Patent Application Laid-Open No. 57-194080, a circular motion type separation method is proposed. However, in this method, flat particles can be efficiently separated, but abnormal shapes such as long, thick, and continuous pellets cannot be sufficiently separated, which is not preferable as a method for producing a thermoplastic resin.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to provide a method for continuously and efficiently obtaining high-quality polymer pellets having a uniform shape in a step of separating the shape of a pelletized thermoplastic resin by a vibration sieve.
[0007]
[Means for Solving the Problems]
That is, the present invention is "a method of producing a pellet of a desired size by separating pellet-shaped resin with a vibration sieve, after dispersing the pellet in the width direction of the sieve surface by a distributor at one end of the vibration sieve, The ratio L / W of the length L and width W of the sieve surface porous portion is 0.5 to 1.5 , and the aperture ratio θ of the sieve surface porous portion is 0.2 to 0.4, This relates to a method for producing a resin pellet characterized by being separated by a vibrating sieve having a value R defined by the following formula (1) of 0.3 to 2.0 .
[Expression 2]

Here, Q (kg / hr) indicates the pellet supply rate.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0009]
FIG. 1A is a schematic view of an example of an apparatus used in the method of the present invention. The pellets that are cut and contain pellets of an undesired size are diffused by the distributor 1 in the width direction of the sieve. The vibrating screen is provided with a sieve surface porous portion 2. The vibration sieve is vibrated by vibration means 6 driven by a motor or the like. Resin pellets having a desired size fall from the pores of the sieve surface porous part 2 to the lower part of the sieve surface and are discharged from the product pellet outlet 3 to the outside of the apparatus. Resin pellets having no desired size pass through the sieve surface porous part and the sieve surface non-porous part, and are discharged from the non-standard pellet discharge port 4 to the outside of the apparatus.
[0010]
The sieve surface porous portion used in the present invention is defined as shown in FIG. 1B, and the relationship between the length L (pellet flow direction) and the width W of the porous portion is 0.5 ≦ L / W ≦ 1. 0.5 is preferable, and 0.7 ≦ L / W ≦ 1.2 is particularly preferable. When L / W is smaller than 0.5, the residence time in the porous portion is shortened, product pellets are mixed into the non-standard pellet discharge port, and the product pellet yield is lowered, which is not preferable. Moreover, when L / W is larger than 1.5, the residence time in the porous portion becomes long, so that non-standard pellets such as long ones are mixed.
[0011]
Regarding the relationship between the pellet supply amount and the sieve size in the present invention, the value of R defined by the formula (1) is preferably in the range of 0.3 ≦ R ≦ 2.
[0012]
[Equation 3]

When the value of R is larger than 2.0, the opening area is large with respect to the amount of pellets supplied, so it is preferable for non-standard pellets such as long parts once sorted to fall from the porous part and be mixed into the product pellets. Absent. On the other hand, when the value of R is smaller than 0.3, the opening area is small with respect to the pellet supply amount, so that the processing capacity is insufficient, the product pellets are discharged from the non-standard pellet discharge port, and the yield of the product pellets is increased. Since it falls, it is not preferable.
[0013]
The distributor 1 used in the present invention aims to disperse the pellets widely in the width direction of the sieve surface.
[0014]
The frequency ν (rpm) of the vibration sieve in the present invention is preferably 1000 ≦ ν ≦ 1700, more preferably 1100 ≦ ν ≦ 1400. When the frequency ν is lower than 1000 vpm, the separation is not sufficiently performed, and the processing ability of the pellet is lowered, which is not preferable. On the other hand, if it is higher than 1700 vpm, the pellets jump up the sieve surface, and the processing ability is remarkably lowered.
[0015]
The amplitude a (mm) is preferably 1 ≦ a ≦ 5. When the amplitude is smaller than 1 mm, the separation is not sufficiently performed, and the processing ability of the pellet is lowered, which is not preferable. On the other hand, when the vibration frequency is larger than 5 mm, the pellets jump up the sieve surface and the processing ability is remarkably lowered.
[0016]
The vibrating sieve used in the present invention can be used in a horizontal installation, but the effects of the present invention can be obtained without any problems even if the screen is tilted backward or forward up to about 10 °.
[0017]
As the vibration means 6 used in the present invention, a vibration motor or any other one may be used. In addition, the motion form given to the sieve surface by the vibration source is a component that combines the pellet flow direction component and the vertical direction component, but the motion form obtained as a result is not limited, and is, for example, elliptical. Alternatively, it may be linear.
[0018]
The method of supplying pellets to the sieve surface in the present invention is effective for either batch type or continuous type.
[0019]
【Example】
Next, the present invention will be described with reference to examples and comparative examples. The physical properties shown in Examples and Comparative Examples were measured as follows.
・ Nylon 66 resin discharged from the reactor with a non-standard pellet mixing rate of 2.5 mm inside diameter was cut at 3.9 mm intervals using a cutter to obtain 1900 kg of cylindrical product pellets of normal dimensions obtained. 2400, 6000, and 7500 kg / hr of pellets with 100 kg (5% by weight of the total) of pellets with an inner diameter or cylinder height exceeding the normal dimension and black pigmented for identification being added. The treatment with a vibrating sieve under predetermined conditions was carried out at the supply speed.
[0020]
After measuring the total amount A (kg) of the product and non-standard pellets obtained from the product pellet outlet, the non-standard pellets are selected, and the non-standard pellet mixing rate B in the total amount A ( %) Was calculated.
[0021]
[Expression 4]

In addition, the non-standard pellet mixing rate of 1.0% or less was set to a satisfactory level that does not affect the molding characteristics.
[0022]
-Product pellet recovery rate (3) The recovery rate r (%) of 1900 kg of the initial product (within standard) pellets was calculated.
[0023]
[Equation 5]

・ 3σ of plasticization time of injection molding
The pellets treated with the vibration sieve were blanked using a Nissei Plastic Industry Co., Ltd. PS-60 type injection molding machine under conditions of a cylinder temperature of 285 ° C., a plasticizing stroke of 0 to 10 cm, and a back pressure of 0.98 MPa. The plasticization time of the shot was measured to obtain the standard deviation σ, and further multiplied by 3 to obtain 3σ. It can be said that the smaller the value 3σ, the better the molding stability.
[0024]
-Size of the sieve screen and the size of the perforated plate part The vibratory sieve device used two types with a sieve surface width W of 130 cm and 90 cm. For the sieving surface, a metal plate for sieving surface was used in which a large number of holes were regularly opened by a required length L, and the remaining part was a part having no holes.
[0025]
About an Example and a comparative example, the total amount A (kg) from a product pellet discharge port, the nonstandard pellet mixing rate B (%), the product pellet recovery rate r (%), and the measurement result of the average value and 3σ of plasticization time Are summarized in Table 1.
[0026]
Example 1
Using a sieve surface with a length L of the porous portion of 100 cm and a width W of 130 cm, the pellet supply rate Q was set to 6000 kg / hr, and the separation treatment was performed. At this time, a distributor was installed in the pellet supply part, and the frequency was 1300 vpm, the amplitude was 3.0 mm, the pore diameter of the porous part was 4.7 mm, and the pore area occupation ratio in the porous part was 28.8%. Since L / W was appropriate as 0.77 and R was 0.62, high quality pellets with low B (%) and small plasticization time 3σ were obtained, and product pellet recovery rate r (%) was also high. became.
[0027]
[Table 1]

[0028]
Example 2
The separation treatment was performed under the same conditions as in Example 1 except that the length L of the porous portion was 150 cm. Since L / W was 1.15 and R was 1.15, high quality pellets with low B (%) and small plasticization time 3σ were obtained, and product pellet recovery rate r (%) was also high. became.
[0029]
Example 3
The sieving process was performed at a pellet supply rate of 6000 kg / hr using a sieve surface having a length L of the porous portion of 80 cm and a width W of 90 cm. Since L / W was 0.89 and R was 0.35, high quality pellets with low B (%) and small plasticization time 3σ were obtained, and the product pellet recovery rate r (%) was also high. became.
[0030]
Comparative Example 1
The sieving treatment was performed under the same conditions as in Example 1 except that the length L of the porous portion was 210 cm. Since L / W was too large at 1.62, B (%) was high, and 3σ of plasticization time was large.
[0031]
Comparative Example 2
The sieving treatment was performed under the same conditions as in Example 1 except that the length L of the porous portion was 50 cm. Since L / W was too small at 0.38, the product pellet recovery rate r (%) was low.
[0032]
Comparative Example 3
The sieving treatment was performed under the same conditions as in Example 3 except that the length L of the porous portion was 210 cm. Since L / W was too large as 2.33, B (%) was high, and 3σ of plasticization time was large.
[0033]
Comparative Example 4
The sieving treatment was performed under the same conditions as in Example 3 except that the pellet supply rate Q was 7500 kg / hr. Since R was too small at 0.28, the product pellet recovery rate r (%) was low.
[0034]
Comparative Example 5
The sieving process was performed under the same conditions as in Example 2 except that the pellet supply rate Q was 2400 kg / hr. Since R was too large at 2.34, B (%) was high, and 3σ of plasticization time was large.
[0035]
Comparative Example 6
The sieving process was performed under the same conditions as in Example 1 except that no distributor was installed. Since the sieve surface was not used effectively, the product pellet recovery rate r (%) was low.
[0036]
【The invention's effect】
By separating the pelletized thermoplastic resin by the vibration sieve of the present invention, high-quality polymer pellets from which abnormally shaped pellets are removed and excellent in molding stability can be obtained in a high yield.
[Brief description of the drawings]
FIG. 1A is a perspective conceptual view of an apparatus used in the method of the present invention. (B) is explanatory drawing of the sieve surface porous part provided in FIG. 1 (A).
[Explanation of symbols]
1. Distributor 2. 2. Sieve surface porous part Product pellet outlet 4. Non-standard pellet outlet 5. 5. Non-sieved part of sieve surface Vibration means

Claims (5)

A method of producing a resin pellet of a desired size by separating pellet-shaped resin with a vibration sieve, and after dispersing the pellet in the width direction of the sieve surface by a distributor at one end of the vibration sieve, The ratio L / W of the length L and the width W is 0.5 to 1.5, the aperture ratio θ of the sieve surface porous portion is 0.2 to 0.4, and the following formula (1) A method for producing resin pellets, wherein the resin pellets are separated by a vibrating sieve having a value R defined by the formula of 0.3 to 2.0 .

Here, Q (kg / hr) indicates the pellet supply rate. Method for producing a resin pellet of claim 1, wherein the sieve surface porous portion of the L / W is 0.7 to 1.2. The method for producing a resin pellet according to claim 1 or 2, wherein the length L of the sieve surface porous portion is 50 to 300 cm. Method for producing a resin pellet according to any one of claims 1 to 3 which is characterized in that the vibration frequency ν is 1000～1700Vpm. The method for producing resin pellets according to any one of claims 1 to 4 , wherein the amplitude a is 1 to 5 mm.

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