JP6473098B2 - Screw for kneading and single screw extruder - Google Patents

Description

The present invention relates to a screw for a single screw extruder and a single screw extruder used for plasticizing and kneading a thermoplastic resin composition.

  When kneading two or more raw materials such as kneading between resins or kneading resin and powder particles, especially when using a thermoplastic resin as the raw material resin to continuously produce a kneaded product, a screw is provided. Kneading is carried out using an extruder. For such kneading by an extruder, a performance is required in which raw materials melted in the extruder are sufficiently kneaded and the kneaded resin composition is discharged in a uniform state. If the material is extruded in a non-uniform manner, the physical properties of the kneaded product are lowered due to the uneven concentration of each component, and when the materials of different colors are kneaded, color unevenness occurs in the kneaded product.

However, the screw in the single-screw extruder has a function of forcibly transferring the supplied raw material to the spiral flow path of the screw by rotating the screw, but the spiral direction is constant. Therefore, there is a problem that a high kneading action cannot be obtained.
In order to improve the kneading performance of the components in the kneading part of the screw, such a measure has been conventionally performed so as to divert the flow of the plasticized material to the screw.
For example, in Patent Document 1, kneading grooves are engraved along the spiral direction as kneading parts of a screw, and the kneading grooves are alternately formed into shallow and narrow shallow groove portions and deep and wide deep groove portions along the spiral direction. There is a structure in which kneading is performed by turbulent flow by continuously forming and connecting shallow narrow grooves with flow paths.

  Kneading by an extruder capable of continuous production is a production method suitable for lowering costs by continuous production compared to batch-type kneading, but in recent years, in order to further reduce production costs, Manufacturing conditions are now required.

However, since these kneaded parts have a complicated raw material flow path in order to improve kneadability, the cross-sectional area of the raw material flow path is narrow, and the shear force applied to the resin composition is greatly increased especially under high discharge conditions. The resin composition at the time tends to generate heat.
Along with this heat generation, the viscosity and elasticity of the molten resin decrease depending on the temperature, and a sufficient force is not applied to the resin composition. In addition, since the resin composition undergoes thermal degradation when the resin composition generates heat, a decrease in physical properties of the resin composition after ejection has also occurred as a problem.

Utility Model 2-82514

An object of the present invention is to provide a screw and an extruder having high kneading performance while suppressing an increase in the resin temperature when kneading and extruding a thermoplastic resin composition.

  In order to solve the problem, the present inventors have intensively studied the structure of the kneaded part of the screw, and as a result, found a structure in which a protrusion is provided in the groove of the kneaded part of the screw, and completed the present invention. .

  Specifically, the kneaded part includes a plurality of spiral flights and grooves, and the spiral grooves have protruding portions that extend from the bottom surface of the spiral grooves in the width direction of the grooves and are raised. A cross-sectional shape in which the convex portion is cut perpendicularly to the bottom surface of the groove in the spiral direction, and the oblique line of the convex portion corresponding to the inclined surface rises in a concave shape from the bottom surface of the groove toward the top of the convex portion. The problem is solved by making the shape of the feature that the width of the top portion of the convex portion is not more than 0.3 times the outer diameter of the screw.

  In a single screw extruder, the resin composition flows along the spiral flight between the spiral groove and the cylinder. However, in the kneaded part having the shape of the present invention, the flow of the resin composition flowing between the groove and the cylinder is inhibited. Thus, a raised portion is formed extending from the bottom surface of the groove in the width direction of the groove.

  Since the top of the convex portion is lower than the depth of the groove, a narrow portion serving as a narrow raw material flow path is formed between the top of the convex portion and the cylinder of the single-screw extruder. Since the convex part is formed over the width direction of the groove, the resin composition flowing in the spiral direction through the screw groove is compressed when flowing into the narrow part, and after flowing out from the narrow part, it is compressed. The formed resin composition is released.

  In the present invention, in the cross-sectional shape in which the convex portion is cut perpendicularly to the bottom surface of the groove in the spiral direction, the oblique line of the convex portion corresponding to the inclined surface rises in a concave shape from the bottom surface of the groove toward the top of the convex portion. In this case, the difference between the channel cross-sectional area immediately before inflowing into the narrow part and the channel cross-sectional area of the narrow part, and the difference between the channel cross-sectional area of the narrow part and the channel cross-sectional area after outflow are large. Become. As a result, the resin composition is rapidly compressed and released in the narrow portion.

The inventors have made the shape of the slope of the convex portion into which the resin composition flows into the shape as described above, so that the kneading effect by compression when the resin composition flows into the narrow portion is large, and the top of the convex portion. It was found that even when the width of the narrow portion is narrowed and there are few sections of the narrow portion where the channel cross-sectional area is small, the shear heat generation of the resin in the narrow portion can be suppressed while obtaining a sufficient kneading effect.
In the case of extruders and screws with different calibers, the amount of the resin composition occupying per unit cross-sectional area of the screw is different, so that the present inventors further investigated with screws with different calibers, and as a result, the width of the top of the convex portion However, it was found that the shear heat generation of the resin can be suppressed if the screw outer diameter is 0.3 times or less.

  In addition, the present inventors have found that by forming the slope of the convex portion on the side from which the resin composition flows out from the narrow portion also has the above shape, the shear heat generation of the resin can be suppressed due to heat absorption due to rapid opening. It was.

  Further, the present inventors have found that the kneading effect by the compression and release reduces the height of the convex portion from the groove, increases the distance between the top of the convex portion and the cylinder, and reduces the cross-sectional area of the narrow portion. It has also been found that the present invention works effectively even when the width is widened, and that the shear heat generation of the resin can be further suppressed as a result of the wide cross-sectional area of the narrow portion.

Further, in order to obtain sufficient kneading, it is preferable to provide a large number of the convex portions in the kneaded part, but the present inventors have determined that the resin composition that has been compressed and released by the convex portions has a certain amount. During this time, the flow in the groove in an open state is sufficiently relaxed, and the force applied in the resin composition during compression is sufficiently relaxed. It has been found that kneading is effectively carried out while suppressing.
From this point of view, it is desirable to provide a plurality of convex portions on each strip by setting the number of spiral portions of the kneaded part to be a plurality of strips. It has been found that if it is 6, the kneading effect can be obtained effectively and the shearing heat generation of the resin can be suppressed.

  Further, the inventors have found that the rise in the resin temperature can be further suppressed by arbitrarily adjusting the pressure of the resin composition flowing into the narrow portion by providing a notch in the spiral flight of the screw. It was.

Moreover, this invention provides the screw provided with the said structure as a kneading component, and the extruder provided with the screw.

  In the present invention, when kneading and extruding the thermoplastic resin composition under high discharge production conditions, a screw and a single screw extruder having high kneading performance can be obtained while suppressing an increase in the resin temperature.

That is, the screw kneading component includes a plurality of spiral flights and grooves, and the spiral groove includes a raised portion extending from the bottom surface of the spiral groove in the width direction of the groove. In the cross-sectional shape in which the convex portion is cut perpendicularly to the bottom surface of the groove in the spiral direction, the oblique line of the convex portion corresponding to the slope is a shape that rises in a concave shape from the bottom surface of the groove toward the top portion of the convex portion, By having a screw for a single screw extruder characterized in that the width of the top part of the convex part is 0.3 times or less of the outer diameter of the screw, it has an excellent kneading effect while suppressing heat generation of the raw materials. A screw and an extruder are obtained.

Sectional drawing which shows the whole of the single screw extruder and screw which concern on this invention Side view of the kneaded part of the present invention FIG. 2 is a view of the vicinity of the protrusion 10 in the A-A ′ cross section of the kneaded part of FIG. FIG. 2 is a view of the vicinity of the convex portion 10 in the A-A ′ cross section of the kneaded part in FIG. 2 when the top of the convex portion is wide Cross section with convex part cut perpendicular to groove bottom in groove spiral direction and resin flow path The shape of the top and slope of the cross section where the convex part is cut perpendicularly to the bottom of the groove in the width direction of the groove Top and slope shapes of cross sections obtained by cutting the convex portions of Comparative Examples 5 and 6 perpendicularly to the bottom surface of the groove in the width direction of the groove

  The present invention is a screw used in a single-screw extruder provided with a kneading part, wherein the kneading part includes a plurality of spiral flights and grooves, and the spiral groove has the spiral shape. In the cross-sectional shape in which a convex portion extending from the bottom surface of the groove and extending in the width direction of the groove is provided, and the convex portion is cut perpendicularly to the bottom surface of the groove in the spiral direction, the oblique line of the convex portion corresponding to the slope is A single-screw extruder characterized in that it has a shape that rises in a concave shape from the bottom of the groove toward the top of the convex portion, and the width of the top portion of the convex portion is not more than 0.3 times the outer diameter of the screw. It is a screw for. Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the single-screw extruder has a cylinder 2 having a hollow inside and a rotatable screw 3 accommodated in the cylinder. The screw has a spiral flight 5 and a groove 6, and by rotating the screw, the raw material supplied from the hopper 4 is supplied in a fixed amount between the heated cylinder 2 and the groove 6 in the extrusion port direction 7. And transport. The raw material transferred between the cylinder 2 and the groove 6 is heated by the heat from the heater 8 wound around the cylinder and the shear heat of the raw material, the cylinder, the raw material, and the screw as it is transferred in the extrusion port direction 7. When heated, the resin melts and the raw material is plasticized.

  As described above, the screw 3 includes a supply unit 31 for quantitatively supplying the material supplied from the hopper 4 as described above, a compression unit 32 for melting the resin in the raw material to plasticize the raw material, and a metering for measuring the plasticized material. The zone 33 is divided into three zones.

  As shown in FIGS. 2 and 5, the kneading part according to the present invention has a multi-groove 6 in a spiral shape, and the helical shape is used to inhibit the flow of the raw material in the groove 6 in the spiral direction. A protruding portion 10 is provided which extends from the bottom surface of the groove in the width direction of the groove and is raised, and a narrow portion 18 serving as a narrow material flow path exists between the top portion 14 of the protruding portion and the cylinder 2.

  In the present invention, in order to obtain rapid compression and release, as shown in FIGS. 5 and 6, the raw material flow path 16 before inflow and the narrow portion 18 and the narrow portion 18 and the raw material flow after inflow are shown. It is necessary that the difference in channel cross-sectional area with the channel 17 is large. From this point of view, and from the viewpoint of eliminating the stagnation part of the flow of the raw material, in the cross-sectional shape in which the convex part is cut perpendicularly to the bottom surface of the groove in the spiral direction, the oblique line of the convex part corresponding to the slope is the groove. It is preferable to have a shape that rises in a concave shape from the bottom surface to the top of the convex portion.

  As shown in FIG. 6, the shape of the oblique line of the convex portion is an imaginary straight line 22-a connecting the vertex 20-a of the convex portion and the point 21-a where the slope of the convex portion starts rising from the bottom surface 15 of the groove. Further, a virtual line 22- showing a shape that is recessed toward the bottom surface side of the groove, and similarly connecting a vertex 20-b of the convex portion and a point 21-b where the slope of the convex portion starts rising from the bottom surface 15 of the groove. The shape which is dented in the bottom face side of a groove | channel is shown from b.

  The curvature of the slope 12 of the convex portion is concave as described above, so that there is a difference in the cross-sectional area between the raw material inflow side and the narrow portion and the raw material outflow side and the narrow portion before and after the convex portion. Since it is born, any curvature may be used. Further, the curvature of the slope 12-a on the inflow side and the slope 12-b on the outflow side to the narrow portion may be different.

In order to suppress an increase in the resin temperature, as shown in FIGS. 3, 5 and 6, the width 19 of the top 14 of the convex portion 10 is preferably a shape with a sharp top so that the width is 0 mm. In the case of the above-mentioned shape, the top portion becomes a blade-like protrusion, causing injury due to the contact of the worker at the time of manufacture, and wear of the protruding portion due to friction with the resin during long-term use. For this reason, as shown in FIG. 4, the width | variety of a top part is good also as 0 mm or more in the range which does not affect the heat_generation | fever of resin.
From this point of view, the width 19 of the top of the convex portion can be preferably 0 to 0.3 times the screw diameter, more preferably 0 to 0.15 times.

In order to obtain sufficient kneading performance, it is preferable to provide a large number of the convex portions 10 in the kneaded part, but the resin composition that has been compressed and released by the convex portions is released for a certain period of time. In the state of flowing through the flow path of the groove, after the force applied in the resin composition at the time of compression is sufficiently relaxed, it is kneaded effectively by being compressed and released at the next convex portion.
From this point of view, a large number of convex portions can be provided by setting the number of spiral portions of the kneaded part to a plurality of strips. However, as the number of strips increases, the cross-sectional area of the grooves decreases and the resin composition flowing through the grooves also generates shear heat. Therefore, the number of strips is preferably 2 to 6.

  By increasing the total length of the kneaded part, a large number of convex portions can be installed. In order to mold at an appropriate resin temperature while suppressing heat generation of the resin, 1/20 to 1/2 of the total length of the screw is preferable, and 1/10 to 1/2 is more preferable.

The higher the height from the bottom surface 12 of the groove of the top portion 14 of the convex portion, the narrower the cross-sectional area of the narrow portion, so that the kneading effect is obtained, and the lower, the cross-sectional area of the narrow portion becomes wider. The shear heat generation of the resin can be suppressed.
The height from the bottom of the groove at the top of the convex portion is preferably 1/10 to 9/10 of the groove depth, more preferably 1/10 to 6/10.

  Since the pressure of the resin composition flowing into the narrow part of each convex part is different in each convex part, the resin flowing into the narrow part 14 of each convex part is able to efficiently suppress the heat generation of the resin composition. In order to arbitrarily adjust the pressure of the composition, a plurality of notches 11 can be provided in the flight portion.

  Since the screw of the present invention exhibits the kneading effect and the effect of suppressing the shear heat generation of the resin as long as the raw material of the kneaded part is plasticized, the kneaded part is the screw weighing unit shown in FIG. 31, or the compression unit 32, or both.

  As shown in FIG. 1, the single-screw extruder of the present invention may be any one provided with the screw 3, and the shape of the cylinder may be a general cylindrical shape, and a groove is arbitrarily provided in the cylinder. It may be a thing.

As mentioned above, although embodiment of this invention was described with reference to drawings, these are the illustrations of this invention, Various structures other than the above are also employable.

  EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited to these. In Examples and the like, “parts” and “%” represent “parts by mass” and “mass%” unless otherwise specified.

(material)
The raw material resin composition used as a raw material described in Examples and Comparative Examples used pellets in which a thermoplastic resin and a pigment were mixed as follows in order to confirm the color at the time of kneading.

Raw material A is linear low density polyethylene (product name: Novatec LL UF230, melt flow rate 1 g / 10 min (JIS K7210: 1999), manufactured by Nippon Polyethylene Corporation) and titanium oxide (product name R-103: manufacturer) 20 parts mixture).

Raw material B: Linear low density polyethylene (product name: Novatec LL UJ790, melt flow rate 50 g / 10 min (JIS K7210: 1999), manufactured by Nippon Polyethylene Corporation) and cyanine blue (product name: Lionol Blue SL: manufacturer Toyocolor) Ltd.) 10 parts mixture.

Raw material C: Linear low density polyethylene (product name: Novatec LL UF230, melt flow rate: 1 g / 10 min (JIS K7210: 1999), manufactured by Nippon Polyethylene Co., Ltd.) and carbon black (product name: BP880: manufacturer: Cabot) Part mixture.

Raw material D: Linear low-density polyethylene (product name: Novatec LL UJ480, melt flow rate 30 g / 10 min (JIS K7210: 1999), manufactured by Nippon Polyethylene Co., Ltd.) and titanium oxide (product name: R-103: manufacturer Chemers Co., Ltd.) 10 parts mixture.

(Method for preparing kneaded resin composition)
The kneaded resin composition was prepared as follows. The machine used for the production was equipped with a screw having the structure described in each example and comparative example in the single screw extruder described in each example and comparative example, and a die hole diameter of 3 mm in the discharge part of the single screw extruder. A die equipped with a die having 5 die holes was used.
Samples were prepared so that the extrusion temperature of the single-screw extruder was 80 ° C. for the supply unit, 150 ° C. for the compression unit, and 240 ° C. for the weighing unit. After mixing the parts by hand blending, it is put into a hopper of a single screw extruder, kneaded and extruded by screw rotation described in each example and comparative example, and the obtained strand is cut into strands so that the length becomes 3 mm. Thus, pellets of the kneaded resin composition were obtained.

(Evaluation of kneadability)
Evaluation of the kneaded state of the kneaded resin composition was carried out as follows.
First, the pellets of the kneaded resin compositions obtained in each Example and Comparative Example were crushed using a hot press to prepare a 20 × 20 × 0.1 cm sheet. The color unevenness of this sheet was visually confirmed and evaluated in three stages of 1 to 3. The lower the numerical value, the more uniform the kneaded material with no color unevenness was obtained on the entire sheet. 1 sheet with uniform color over the entire sheet, 1 minute color unevenness was observed in the crushed pellets The number of sheets to be obtained was 2, and the number of sheets in which color unevenness was observed over the entire surface of the crushed pellets was designated 3. The lower the value, the more uniformly kneaded. The results are shown in Table 1.

(Evaluation of increase in resin temperature during kneading)
The evaluation of the rise in the resin temperature at the time of preparing the kneaded resin compositions in Examples and Comparative Examples was performed by measuring the molten resin discharged from the extruder die with a thermometer, and the resin temperature relative to the set temperature of the extruder of 240 ° C. The rise was evaluated, and a resin temperature of 255 ° C. or higher at which the extruder set temperature + 15 ° C. or higher was evaluated as x (defect), and a lower temperature was evaluated as ◯ (good).

The following two types of extruders used in each example and comparative example were used in order to compare those having different cylinder diameters.
Extruder A PSV-30 Extruder (Tanifuji Engineering Co., Ltd., cylinder diameter 30mm)
Extruder B SPM-45 Extruder (manufactured by Tanifuji Engineering, cylinder diameter 45mm)

<Examples 1 and 2>
A single screw extruder of Extruder A was used for a screw having a screw outer diameter of 30 mm and a screw having a ratio of screw length to screw outer diameter (L / D) = 36 and having the following kneaded parts in the compression section.
(A) Number of strips 3 strips (b) Locations of projections 1 location per pitch period of each groove (c) Slope of projections As shown in FIG. Shape that rises in a concave shape toward the top (d) Width of the top of the convex 1 mm (ratio with screw outer diameter 0.03)
(E) Height from the bottom of the groove at the top of the convex part 3/10 to the groove depth of the kneading part
(F) Length of the kneaded part 360 mm (1/3 of the total screw length)

Using the single screw extruder, 50 parts of raw material A and 50 parts of raw material B were kneaded under the conditions of a screw rotation of 150 rpm in Example 1 and a high speed of 200 rpm in Example 2, and evaluation was performed. The configuration of the screw was a single full flight configuration except for the kneaded parts.
Each evaluation result is shown in Table 1. In both Example 1 and Example 2, good results were obtained for both evaluation of kneadability and evaluation of increase in resin temperature.

<Examples 3 and 4>
Using the same screw and extruder as in Examples 1 and 2, the raw material was changed to 50 parts of raw material C and 50 parts of raw material D. In Example 3, the screw rotation was 150 rpm, and in Example 4, high speed was 200 rpm. Kneading and evaluation were performed.
Each evaluation result is shown in Table 1. In both Example 3 and Example 4, even when the raw materials were changed from Example 1 and Example 2, good results were obtained for both evaluation of kneadability and evaluation of increase in resin temperature.

<Examples 5 and 6>
As the configuration of the screw, from Examples 1 and 2, the place where the kneaded part was provided in the screw was changed to a measuring section, and the part other than the kneaded part was configured as a single full flight. The configuration of the kneaded parts and the single screw extruder were the same as those in Examples 1 and 2.
In the same manner as in Examples 1 and 2, 50 parts of the raw material A and 50 parts of the raw material B were kneaded and evaluated under the conditions of a screw rotation of 150 rpm in Example 5 and a high speed of 200 rpm in Example 6. .
Each evaluation result is shown in Table 1. In both Example 5 and Example 6, good results were obtained for both evaluation of kneadability and evaluation of increase in resin temperature.

<Examples 7 and 8>
The number of kneaded parts was changed from those in Examples 1 and 2 to be 6. The other components of the kneading part and screw, and the single screw extruder were the same as those in Examples 1 and 2.
In the same manner as in Examples 1 and 2, 50 parts of the raw material A and 50 parts of the raw material B were kneaded and evaluated under the conditions of a screw rotation of 150 rpm in Example 7 and a high speed of 200 rpm in Example 8. .
Each evaluation result is shown in Table 1. In both Example 7 and Example 8, good results were obtained in both evaluation of kneadability and evaluation of increase in resin temperature.

<Examples 9 and 10>
The width of the top of the convex part of the kneaded part was changed from Examples 1 and 2 to 9 mm (ratio with screw outer diameter 0.3). The other components of the kneading part and screw, and the single screw extruder were the same as those in Examples 1 and 2.
In the above-described configuration, as in Examples 1 and 2, 50 parts of raw material A and 50 parts of raw material B were kneaded and evaluated under the conditions of a screw rotation of 150 rpm in Example 9 and a high speed of 200 rpm in Example 10. .
Each evaluation result is shown in Table 1. In both Example 9 and Example 10, good results were obtained in both evaluation of kneadability and evaluation of increase in resin temperature.

<Examples 11 and 12>
In order to change the screw outer diameter, the single screw extruder was changed to the extruder B, and a screw having an outer diameter of 45 mm, L / D = 36, and the following kneading parts provided in the compression part was used.
(A) Number of strips 3 strips (b) Locations of projections 1 location per pitch period of each groove (c) Slope of projections As shown in FIG. Shape that rises in a concave shape toward the top (d) Width of the top of the convex 13 mm (ratio with screw outer diameter 0.29)
(E) Height from the bottom of the groove at the top of the convex part 3/10 to the groove depth of the kneading part
(F) Length of kneaded parts 540 mm (1/3 of the total length of the screw)

The screw was provided in an extruder, and 50 parts of raw material A and 50 parts of raw material B were kneaded and evaluated under the conditions of a screw rotation of 150 rpm in Example 1 and a high speed of 200 rpm in Example 2. The configuration of the screw was a single full flight configuration except for the kneaded parts.
Each evaluation result is shown in Table 1. In both Example 11 and Example 12, good results were obtained in both evaluation of kneadability and evaluation of increase in resin temperature.

<Examples 13 and 14>
The flight of the kneaded parts of the screws of Examples 1 and 2 was provided with a notch having a length of 6 mm and a depth of 3 mm from the top of the screw at a position half a pitch away from each convex portion. The other components of the kneading part and screw, and the single screw extruder were the same as those in Examples 1 and 2.
In the same manner as in Examples 1 and 2, 50 parts of the raw material A and 50 parts of the raw material B were kneaded and evaluated under the conditions of a screw rotation of 150 rpm in Example 13 and a high speed of 200 rpm in Example 14. .
Each evaluation result is shown in Table 1. In both Example 13 and Example 14, good results were obtained for both evaluation of kneadability and evaluation of increase in resin temperature.

<Comparative Examples 1 and 2>
The width of the top of the convex part of the kneaded part was changed from Examples 1 and 2 to 13 mm (ratio 0.43 with respect to the screw outer diameter). The other components of the kneading part and screw, and the single screw extruder were the same as those in Examples 1 and 2.
In the above-described configuration, as in Examples 1 and 2, 50 parts of raw material A and 50 parts of raw material B were kneaded and evaluated under the conditions of a screw rotation of 150 rpm in Comparative Example 1 and a high speed of 200 rpm in Comparative Example 2. .
Each evaluation result is shown in Table 1. In Comparative Example 1 and Comparative Example 2, both the kneadability evaluation and the evaluation of the resin temperature increase were poor.

<Comparative Examples 3 and 4>
The width of the top of the convex part of the kneaded part was changed from Examples 3 and 4 to 13 mm (ratio with screw outer diameter 0.43). The other components of the kneading part and screw, and the single screw extruder were the same as those in Examples 3 and 4.
In the above configuration, as in Examples 3 and 4, 50 parts of raw material C and 50 parts of raw material D were kneaded and evaluated under the conditions of a screw rotation of 150 rpm in Comparative Example 3 and a high speed of 200 rpm in Comparative Example 4. .
Each evaluation result is shown in Table 1. In Comparative Example 3 and Comparative Example 4, both the kneadability evaluation and the evaluation of the increase in the resin temperature were poor.

<Comparative Examples 5 and 6>
As shown in FIG. 7, the cross-sectional shape of the slope of the convex part of the kneaded part is as follows: apexes 20-a and 20-b of the top part 14 of the convex part, and points 21-a and 21-b rising from the bottom of the groove The slanting line corresponding to the slope of the convex portion is a straight line. The other kneading parts and other configurations of the screw and the single screw extruder were the same as those in Examples 1 and 2.
In the above-described configuration, as in Examples 1 and 2, 50 parts of raw material A and 50 parts of raw material B were kneaded and evaluated under the conditions of a screw rotation of 150 rpm in Comparative Example 5 and a high speed of 200 rpm in Comparative Example 6. .
Each evaluation result is shown in Table 1. In Comparative Example 5 and Comparative Example 6, both the kneadability evaluation and the evaluation of the resin temperature increase were poor.

<Comparative Examples 7 and 8>
The number of kneaded parts was changed from those in Examples 1 and 2 to one. The other components of the kneading part and screw, and the single screw extruder were the same as those in Examples 1 and 2.
In the above-described configuration, as in Examples 1 and 2, 50 parts of raw material A and 50 parts of raw material B were kneaded and evaluated under the conditions of a screw rotation of 150 rpm in Comparative Example 7 and a high speed of 200 rpm in Comparative Example 8. .
Each evaluation result is shown in Table 1. In Comparative Example 7 and Comparative Example 8, the kneadability evaluation was poor.

The present invention relates to a single screw extruder, and more particularly to increasing the throughput of a resin composition for melt kneading.

DESCRIPTION OF SYMBOLS 1 Kneading part 2 Cylinder 3 Screw 4 Hopper 5 Screw flight 6 Screw groove 7 Direction of extrusion port 8 Heater of single screw extruder 9 Die 10 Protruding part 11 Flight notch 12 Diagonal line 12-a equivalent to convex slope The oblique line 12-b corresponding to the slope of the convex part on the inflow side The oblique line 14 corresponding to the slope of the convex part on the raw material outflow side 14 The top part 15 of the convex part 16 The bottom of the groove 16 The flow of the resin on the raw material inflow side 17 Flow 18 Narrow part flow path 19 between the cylinder and the top of the convex part 19 Width of the top part of the convex part 20-a Vertex 20-b of the convex part on the raw material inflow side Apex of the oblique line 12 of the convex part on the raw material outflow side 21-a Point at which rising of the oblique line of the convex part on the raw material inflow side starts 21-b Point at which the oblique line of the convex part on the raw material outflow side starts to rise 22-a Virtual line connecting the apex of the convex part on the raw material inflow side and the point at which the rising starts 22 Height from the groove of the top portion of the metering section 41 the convex portion of the compression section 33 the screw of the supply portion 32 screw imaginary straight line 31 screw connecting points starting vertices and rising of the convex portion of the b material outflow side

Claims (4)

A screw used in a single-screw extruder provided with kneading parts, wherein the kneading parts are provided with a plurality of spiral flights (except for sub flights whose flight height is lower than the main flight) and grooves. The spiral groove is provided with a raised portion that extends from the bottom surface of the spiral groove in the width direction of the groove, and a cross section in which the raised portion is cut perpendicularly to the bottom surface of the groove in the spiral direction. In the shape, the oblique lines on both sides of the convex portion corresponding to the slope are shapes that rise concavely from the bottom of the groove toward the top of the convex portion, and the width of the top portion of the convex portion is 0.3 of the outer diameter of the screw. A screw for a single-screw extruder, characterized in that it is twice or less. The screw according to claim 1, wherein a cut is provided in the flight. The screw according to claim 1 or 2, wherein the flight and the groove are 2-6. A single-screw extruder comprising the screw according to any one of claims 1 to 3.