JP2660271B2 - Method for producing thermoplastic resin composition - Google Patents

Description

The present invention relates to a method for producing a thermoplastic resin composition. More specifically, in the production of a composition in which a lubricant is blended with a thermoplastic resin, the problems of poor plasticization of the resin, poor kneading, reduced productivity, and the like are improved, and the addition and dispersion of the lubricant is more effectively performed. The present invention relates to a production method for obtaining a composition having excellent friction and wear characteristics.

[Conventional technology and its problems]

As a means for improving the friction and wear characteristics of a thermoplastic resin, it is widely used to add a lubricant to the thermoplastic resin. As an apparatus for producing such a resin composition, a single-screw extruder having a circular cylinder having a circular cross section perpendicular to the axial direction or a twin-screw extruder having a cylinder having a cross section combining two circular shapes is generally used. It is used. In addition, in order to improve kneading, as a screw, a dalmage type screw or a Murdoch type screw is used in the case of a single screw extruder, and a kneading disc element and a reverse screw element are combined in a segment type screw in the case of a twin screw extruder. Screws with different shapes are often used.

However, it is well known that a method of producing a resin composition in which a lubricating oil is blended with a thermoplastic resin using an extruder as described above has many problems to be solved. Due to the sliding of the resin on the screw due to the action of, and it is difficult to apply a uniform and sufficient shearing force to the entire resin, not only causes problems such as poor plasticization of the resin and a decrease in the extrusion amount, Since it is difficult to uniformly disperse the lubricant in the resin, it is difficult to obtain a composition exhibiting excellent friction and wear characteristics, and the like.Therefore, there is a strong demand for a production method that solves these problems. Was rare.

[Means for solving the problem]

The present inventor has solved the above-mentioned problem in the production of a composition comprising a lubricant mixed with a thermoplastic resin, and has enabled a stable production of a composition containing a lubricant and further improved friction and wear properties. As a result of intensive studies on a production method for obtaining a composition having the following formula, it has been found that these problems can be solved at once if an extruder having a specific cylinder inner surface shape is used, and the present invention has been achieved.

That is, the present invention provides a method for producing a composition comprising (A) a thermoplastic resin and (B) 0.01 to 10% by weight (in the composition) of a lubricating oil agent. The present invention relates to a method for producing a thermoplastic resin composition, which comprises kneading using an extruder provided with at least one portion having a substantially polygonal shape and extending in the axial direction thereof.

First, the resin composition to which the present invention is applied will be described.

The thermoplastic resin (A) used in the present invention is not particularly limited. For example, crystalline resins such as polyethylene, polypropylene, polyacetal, polyamide, polyarylene sulfide, polyester (polyethylene terephthalate, polybutylene terephthalate, wholly aromatic polyester, etc.) Amorphous thermoplastic resins such as thermoplastic resin, polyvinyl chloride, polystyrene, ABS resin, AS resin, polyacrylate, polymethacrylate, polycarbonate, polyphenylene oxide, polyethersulfone, and polysulfone are exemplified. These resins may be modified by grafting, crosslinking and the like. In the present invention, one or more selected from these resins are used. The effects of the present invention are remarkable when a polyacetal resin, a polyester resin, and a polyarylene sulfide resin are used.

Further, as the lubricating oil (B) to be blended therein, any known lubricating oil which is liquid at normal temperature or at least at the extrusion temperature can be used. For example, turbine oil, machine oil, engine oil, gear oil, spindle oil, refrigeration oil, petroleum lubricating oil such as paraffin oil, soybean oil, coconut oil,
Animal and vegetable oils such as palm oil, cottonseed oil, linseed oil, rapeseed oil, castor oil, whale oil, squalene, various silicone oils,
Polyalkylene glycol oil, polyphenyl ether oil, polyolefin oil, fatty acids having 11 or more carbon atoms, carbon number
Examples include 11 or more aliphatic alcohols, esters composed of aliphatic and monohydric or polyhydric alcohols, alcohol adducts to polyalkylene glycol, aliphatic amides, metal salts of fatty acids, and fluorine-based surfactants. In the present invention, one or more selected from these lubricants are used. Particularly preferred are silicone oils and esters composed of fatty acids and monohydric or polyhydric alcohols. It is also possible to use a substance having the property of retaining the lubricant such as a substance having an affinity for these lubricants or an inorganic substance having a large specific surface area as a holding material.

In the present invention, the amount of the lubricating oil agent (B) is 0.1.
01 to 10% by weight (in the composition). If the amount is less than 0.01% by weight, the friction and wear characteristics of the thermoplastic resin (A) cannot be sufficiently improved, and when such a small amount of lubricating oil is blended, the production using a conventional extruder is required. There is no particular problem in the production method, and the significance of applying the production method of the present invention is small. Conversely, the amount of lubricant added is 10
If the amount is more than 10% by weight, not only properties such as mechanical, physical, and chemical properties inherent to the thermoplastic resin (A) as a base material are lost, but also the processing is performed even when the production method of the present invention is applied. The properties may be impaired, which is not preferred. The amount of the lubricating oil (B) is preferably 0.1 to 5% by weight, particularly preferably 0.2 to 3% by weight. With the application of the production method of the present invention, there is no problem during production and further excellent friction and wear are achieved. A composition having properties and the like is obtained.

Further, the composition obtained by the present invention, known additives generally added to the thermoplastic resin, namely stabilizers such as antioxidants and ultraviolet absorbers, antistatic agents, flame retardants, flame retardant auxiliary, A coloring agent such as a dye or a pigment, a crystallization accelerator (nucleating agent), or a fibrous, powdery, or plate-like inorganic filler can be appropriately added according to required performance.

The present invention is characterized by using an extruder having a cylinder having a specific cross-sectional shape, as described above and as described in detail below, in producing the composition as described above.

Hereinafter, an example of a twin-screw extruder will be described and its features will be described with reference to the drawings. However, the extruder used in the present invention is not limited to this, and may be a single-screw or three- or more-screw extruder. There may be. The most preferred is a twin-screw extruder in view of kneading properties, operability, economy and the like.

First, FIGS. 1 and 2 show one embodiment of an extruder used in the present invention. FIG. 1 is a schematic cross-sectional view in a lateral direction, and FIG. 2 is a schematic cross-sectional view in a plane. It is. In the section indicated by Y in the drawing, the cross-sectional shape perpendicular to the axial direction of the inner wall of the cylinder is substantially polygonal as shown in FIG. 3 as an example of a cross section taken along the line II. Is formed in the shape of two regular hexagons), and the feature of the present invention resides in that an extruder having such a specific cylindrical shape is used. It is necessary to provide at least one step of the specific cylinder cross-sectional shape from the plasticizing portion of the resin to the tip of the extruder, but it is of course possible to provide two or more steps. This shape may be applied over the entire length. In particular, from the point of 1/3 between the feed section of the extruder and the nozzle, 2/3
It is preferable to provide at least one step of the specific shape portion including an arbitrary point in a section up to the point. The length of the specific shape portion is not particularly limited, but if it is too short, the kneading effect is weak, and in order to obtain a sufficient kneading effect, the total length of the specific shape portion is calculated as the total length of the cylinder.
It is preferably at least 20%.

Next, the shape of the cross section of the cylinder inner wall perpendicular to the axial direction will be described. FIG. 3 shows an example of a cross section taken along line II in a portion (Y in FIG. 1) having a polygonal cross section perpendicular to the axial direction of the inner wall of the cylinder. Here, an example of a regular hexagonal shape (a shape combining two regular hexagons for a twin-screw extruder) is shown as a cross-sectional shape, but the polygonal shape employed in the present invention is limited to this shape. Instead, polygons such as a triangle, a quadrangle, a pentagon, a heptagon, and an octagon are all possible.
When the number of corners of the polygon is small, the movement of the resin at the corners becomes poor, the kneading action is weakened, and the discoloration and deterioration due to stagnation of the resin are likely to occur. Conversely, when the number of corners is large, the resin at the corners is The kneading action by the position exchange becomes weak. Therefore, the polygon is preferably a pentagonal to octagonal shape. The cross-sectional shape is not only a regular polygon as shown in FIG. 3 (in FIG. 3, a combination of two regular hexagons) but also a fourth polygon.
As shown in the figure, a polygon having a shape obtained by cutting off corners of a regular polygon, as shown in FIG. 5, one having a rounded corner, and a phase shift of two or more polygons as shown in FIG. The shape may be a shape obtained by combining the above shapes, or a shape having concave or convex roundness at the sides of the polygon as shown in FIG. There is no particular limitation on the cross-sectional shape of the cylinder other than the portion (Y in FIG. 1) other than the portion having a polygonal cross section perpendicular to the axial direction of the inner wall of the cylinder. What is necessary is just to adopt the circular shape (or the shape which combined the circular shape).

 Next, the extruder screw will be mentioned a little.

The extruder used in the present invention is characterized by the shape of the cylinder as described above, and there is no special restriction on the shape of the screw, and a conventionally known one-, two- or three-thread screw, etc. And in a twin screw extruder, both co-directional screw rotation and different-direction screw rotation are possible. Further, in a single-screw extruder, a screw having a dull-mage portion may be provided, and in a twin-screw extruder, a screw having a shape in which a kneading disc and a reverse screw element are combined in a segment system may be used. It is particularly preferred that a twin-screw extruder rotating in the same direction be used as the extruder, and the section of the cylinder inner wall perpendicular to the axial direction be substantially polygonal and extend in the axial direction (for example, Y in FIG. 1). Part or all of the screws corresponding to ()) are completely meshed type double-start screws (for example, FIG. 3).
Alternatively, it is formed by a completely meshing three-thread screw (for example, FIG. 8). Further, a screw corresponding to a portion (for example, Y in FIG. 1) in which the cross-sectional shape perpendicular to the axial direction of the cylinder inner wall is substantially polygonal and extends in the axial direction,
It is also preferable to provide one or more reverse screw portions for feeding the resin in the direction opposite to the direction in which the resin travels, whereby the inside of the cylinder is filled with the molten resin and kneading can be performed effectively.

In the present invention, there is no particular limitation on the production of a composition in which the lubricant (B) is blended with the thermoplastic resin (A) except for using the special extruder as described above. The methods, conditions, etc. used can be used. For example,
A method in which the component (A) and the component (B) are mixed in advance and extruded, a method in which the component (A) and the component (B) are supplied to the same position or in separate positions without being mixed in advance and extruded, Any one of the methods of extruding either or both of the component (B) and the component (B) can be used, and conditions such as temperature conditions and screw rotation speed are appropriately selected according to the characteristics of the resin. Is done.

〔Example〕

Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.

Examples 1 to 8 and Comparative Examples 1 to 8 A polyacetal resin, a polybutylene terephthalate resin and a polyphenylene sulfide resin were used as the thermoplastic resin (A). Added as material)
Was prepared using an extruder specified in the present invention, and the extrudability and the obtained composition were evaluated.
The extruder used here has a structure as shown in FIG. 1 and FIG. In this figure, the cylinder of the extruder is of a replaceable type in a block system, and the cylinder part corresponding to Y in the figure has a regular hexagonal cross section perpendicular to the axial direction as shown in FIG. The other portion (X, Z in the drawing) has an inner wall having a combined shape, and the other portion has an inner wall having a shape in which two circular shapes are combined. Also,
The screw is a segment type. In FIG. 1 (or FIG. 2), the element corresponding to the Y portion is a completely meshing type double thread, and a reverse screw element is used on the nozzle side of the portion. In this portion, sufficient plasticizing kneading is performed.

For comparison, the same composition as in the example was manufactured using a twin-screw extruder in which the cross-sectional shape perpendicular to the axial direction of the cylinder inner wall was formed by combining two circles over the entire axial direction,
The same evaluation was performed.

 The results are shown in Table 1.

 In addition, evaluation was performed by the following method.

Extrudability (findings at the time of preparing the composition pellets): The state of biting of the resin into the screw during extrusion,
Vent-up, foaming state of the strand, surging development, etc. were visually observed and evaluated in a total of 5 levels.

Tensile strength and elongation: According to ASTM D-638 Practical sliding test: Using the tester shown in Fig. 9, using the guide roller shown in Fig. 10 in combination with a metal shaft as shown in Fig. 11 The motor was slid at a contact load of 100 g and a rotation speed of 5500 rpm for 48 hours, and a motor load current value was measured as a measure of the rotation torque, and evaluated by the average value and the variation.

[Effects of the Invention] As is clear from the above description and Examples, in producing a composition obtained by blending a lubricant with a thermoplastic resin, the cross-sectional shape perpendicular to the axial direction of the cylinder inner surface is a polygon. According to the method of the present invention using an extruder,
Without causing problems of poor plasticization and poor productivity at the time of extrusion, it is possible to uniformly disperse the lubricant in the thermoplastic resin. This is a very preferable manufacturing method.

[Brief description of the drawings]

FIGS. 1 and 2 show one of the extruders used in the present invention.
1 is a schematic cross-sectional view in a lateral direction, and FIG. 2 is a schematic cross-sectional view in a plane. FIG.
FIG. 2 is a schematic cross-sectional view taken along a line II in FIG. 2 (or FIG. 2);
An example in the case of a thread screw is shown. 4 to 7 show modifications of the cross-sectional shape of the cylinder shown in FIG. 3, and FIG. 8 shows an example in the case of a screw having three threads. 9 (A) and 9 (B) are schematic side and plan views of a tester used for a practical test of slidability, and FIGS.
(B) is a side view and a plan view of a guide roller used for the test, and FIG. 11 is a side view showing a state where the guide roller is combined with a metal shaft. 1: Cylinder 2: Screw 3: Kneading disk (feed screw) 4: Kneading disk (reverse screw) Y: Polygonal cylinder cross section X, Z: Conventional (circular) cylinder cross section 5: Guide Roller 6: Metal shaft 7: Rotating motor 8: Ammeter 9: Rotating plate (metal plate with rubber on the circumference) 10: Spring P: Contact load (100g)

Claims (3)

(57) [Claims] (1) A thermoplastic resin is added to (B) a lubricant oil.
In producing a composition containing from 0.01 to 10% by weight (in the composition), at least a part of the inner wall of the extruder cylinder whose cross section perpendicular to the axial direction is substantially polygonal and extends in the axial direction is at least A one-stage co-rotating twin-screw extruder, wherein a screw corresponding to a portion extending in the axial direction of an inner wall of a cylinder has a portion formed by a completely meshing double or triple screw, and includes a reverse screw portion. A method for producing a thermoplastic resin composition, comprising kneading using an extruder. 2. An extruder wherein the cross section of the inner wall of the cylinder at right angles to the axial direction is substantially polygonal and the total length of the portion extending in the axial direction is at least 20% of the entire length of the cylinder. 2. A method for producing the thermoplastic resin composition according to item 1. 3. The section of the cylinder inner wall perpendicular to the axial direction at right angles to the axis is substantially polygonal, and the portion extending in the axial direction is defined as 2/3 from the point 1/3 between the feed section of the extruder and the nozzle. 3. The method for producing a thermoplastic resin composition according to claim 1, wherein at least one extruder including any one of the sections up to point 3 is provided.