JP2004263126A - Manufacturing method of resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To manufacture a resin composition having a uniform composition stably at a low cost without using a spreading agent, employing a master batch method or an after-blending method or installing a plurality of hoppers in the manufacture of the resin composition by mixing a chip-like resin with particularly a powdery additive having a low bulk density. <P>SOLUTION: In the manufacture of the resin composition by mixing the chip-like resin with the powdery additive having a bulk specific gravity of less than 0.19 g/mL, the powdery additive is mixed after subjected to a treatment for increasing its bulk specific gravity. The manufacturing method is useful particularly in the manufacture of a resin composition where the chip-like resin is mixed in advance with the powdery additive and the mixture is introduced through one inlet into an extruder, melted and kneaded. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing a resin composition by mixing a chip resin and a powdery additive.
[0002]
[Prior art]
Polyester-based resins are used in various fields because of their crystallinity, strength, and chemical resistance.
Among polyester-based resins, for example, polybutylene terephthalate (PBT) is particularly excellent in chemical resistance, has a high melting point and good heat resistance, and furthermore is easy to be flame-retardant and excellent in electrical insulation. -Molded into various industrial parts such as electronic parts and automobile parts.
After melt polymerization, such PBT is usually formed into a chip having a size of rice grains. Thereafter, powdery additives such as a coloring agent, a stabilizer, a flame retardant, a non-drip agent, and an inorganic filler are melt-mixed as necessary to the chip-shaped PBT and formed into various industrial parts as described above. (For example, see Patent Document 1).
[0003]
Here, when melt-mixing the chip-shaped PBT and the powdery additive to form a resin composition, a twin-screw extruder 20 as shown in FIG. 2 may be used.
In this twin-screw extruder 20, a predetermined amount of chip-shaped PBT and a powdery additive are charged, and a rotary blender 21 in which these are mixed for a predetermined time, and a mixture mixed by the blender 21 are charged by dropping. And one hopper 22. The mixture put into the hopper 22 enters the barrel 23, is melted and kneaded in the barrel 23, and is extruded from the round die 25 by two screws 24. The strand-shaped resin composition extruded from the round die 25 is appropriately cut into a resin composition chip, which is used for various moldings.
[0004]
[Patent Document 1]
JP-A-53855 / 2005 [0005]
[Problems to be solved by the invention]
However, when the resin composition is manufactured by mixing the chip-shaped PBT and the powdery additive in this way, the chip-shaped PBT and the powdery additive are previously homogeneously mixed with a stirring mixer such as a blender. And the powdered additive has a different falling speed from the blender to the hopper, the ratio between the chip-shaped PBT and the powdered additive in the mixture charged into the barrel. May change with time, and may differ between the initial stage and the later stage of the introduction. As a result, the resin composition extruded from the round die in the early stage of the extrusion process contains a large amount of PBT having a high falling speed, and the resin composition extruded from the round die in the late stage of the extrusion process becomes a powdery material having a low falling speed. There is a problem that the resin composition to be produced tends to be heterogeneous because it contains many additives. In particular, among the powdery additives, fine powder of silicon dioxide added as a non-drip agent has a low bulk specific gravity and contains a lot of air, so that the falling speed is very low, and most of the powder is used in the extrusion process. In many cases, the resin composition extruded after the latter period was unevenly contained.
[0006]
In order to solve such a problem, a method in which a part of PBT and a powdery additive are melt-mixed in advance to obtain a master batch, and then the master batch and the remaining PBT are melt-mixed (master batch) Method), a method of mixing the resin composition obtained in the early stage of the extrusion process with the resin composition obtained in the late stage to homogenize the composition (after blending method), and preliminarily making the surface of the chip-shaped PBT a surfactant. There is a method in which a powdery additive is coated with a spreading agent made of such as above so that the powdery additive is easily adsorbed uniformly on the surface of the chip-shaped PBT. In addition, the chip-shaped resin and the powdery additive are not mixed in advance with a blender or the like, but are separately charged from separate hoppers, so that the respective drop speeds are individually controlled, and the homogeneity of the resin composition is controlled. There is a way to achieve this.
[0007]
However, the masterbatch method and the after-blending method are troublesome and increase the production cost of the resin composition.In the method using a spreading agent, the addition of the spreading agent stabilizes the quality of the resin composition. In some cases. Further, in the case of a method in which the chip-shaped resin and the powdery additive are charged from different hoppers, it is necessary to provide two or more hoppers, and there is a problem in terms of equipment cost.
[0008]
The present invention has been made in view of the above circumstances, when mixing a chip-shaped resin, especially a powdery additive having a small bulk specific gravity to produce a resin composition, using a spreading agent, a master, An object of the present invention is to provide a method for producing a resin composition having a homogeneous composition stably and at low cost without employing a batch method or an after-blending method, or providing a plurality of hoppers.
[0009]
[Means for Solving the Problems]
The method for producing a resin composition according to the present invention is characterized in that the chip-like resin is mixed with a powdery additive having a bulk specific gravity of less than 0.19 g / ml to produce the resin composition. It is characterized by mixing after increasing the bulk specific gravity.
The production method of the present invention is particularly useful in the case where the chip-shaped resin and the powdery additive are preliminarily mixed and charged into an extruder from one input port, and then melted and kneaded to produce a resin composition. is there.
It is preferable that the bulk specific gravity increasing process granulates the powdery additive.
The chip resin is preferably a polyester resin.
The production method of the present invention is suitable for the case where the chip-shaped resin is a polyester resin and the case where the powdery additive contains at least silicon dioxide.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
The method for producing a resin composition according to the present invention includes the steps of: mixing a chip-like resin with a powdery additive having a bulk specific gravity of less than 0.19 g / ml to produce a resin composition; The mixture is mixed after the specific gravity increasing process.
Here, the chip shape refers to a cylindrical shape having a diameter of 1 to 3 mm and a height of about 2 to 5 mm, an elliptic column shape, a polygonal column shape having a side length of 1 to 3 mm, a height of about 1 to 5 mm, or a diameter of about 2 to 3 mm. The resin is generally formed by extruding a resin after melt polymerization into a strand, cutting the resin, and forming the resin into a granular form.
[0011]
The type of resin of the chip-shaped resin is not limited as long as it is formed and handled in the shape of a chip, for example, a polyester resin, a polyolefin resin, a styrene resin, a polyvinyl chloride resin, a polyamide resin, Examples thereof include a polycarbonate resin, a polyphenylene ether resin, an acrylic resin, and a fluorine resin. One or more of these may be used. Among them, PBT, polyethylene terephthalate, polyethylene naphthalate, and polypropylene terephthalate And polyester resins such as polyhexamethylene terephthalate and polycyclohexane dimethylene terephthalate. Furthermore, PBT is preferable because the shape after polymerization is generally a chip shape.
[0012]
As the powdery additive to be mixed with the chip-shaped resin, the bulk specific gravity calculated by measuring the bulk (volume) of a certain mass of the powdery additive with a measuring cylinder and dividing the mass by the bulk is 0. There is no limitation as long as it is less than .19 g / ml and is usually used as an additive for resins.
Examples of such powdery additives include silicon dioxide fine powder (Carplex # 80-D manufactured by Shionogi Pharmaceutical Co., Ltd., bulk specific gravity 0.07 to 0.11 g / ml), Tokuseal manufactured by Tokuyama (bulk specific gravity 0.17 g / ml) And the like.
[0013]
As a method for increasing the bulk specific gravity of a powdery additive having a bulk specific gravity of less than 0.19 g / ml, for example, using a dry granulator 10 as shown in FIG. There is a method of granulating while degassing the additive.
The dry granulator 10 of this example includes a screw 11a, a hopper 11 that is an input port into which the powdery additive is charged, and a transfer unit 12 that includes a screw 12a that transfers the powdery additive from the hopper 11. And a pair of rolls 13 for pressing the transferred powdery additive, a crusher 14 for crushing the pressed powdery or strip-shaped powdery additive, and a crushed or strip-shaped powdery additive. A sizing machine 15 for sizing the powdery additive. A supply unit 16 is provided between the transfer unit 12 and the roll 13 for temporarily holding the powdery additive before being supplied to the roll 13. The hopper 11, the transfer section 12, and the supply section 16 are connected to a degassing means (not shown) such as a decompression pump so that the powdery additive can be degassed in each of them.
[0014]
A powdery additive having a bulk specific gravity of less than 0.19 g / ml is supplied to the hopper 11 of such a dry granulator 10, and the powdery additive is removed at the hopper 11, the transfer unit 12, and the supply unit 16 while being transferred to the roll 13. By pressing with a pair of rolls 13, the powdery additive is pressed into small pieces or strips. Thereafter, by sequentially passing through the pulverizer 14 and the granulator 15, a granulated product of the powdery additive having an increased bulk specific gravity is obtained.
[0015]
When producing a resin composition by mixing the granulated material of the powdery additive and the chip-shaped resin obtained by such a bulk specific gravity increasing treatment, a mixing machine or the like that mixes these while melting them as appropriate Just use it. Here, a method using the twin-screw extruder 20 of FIG. 2 will be exemplified and specifically described.
First, a predetermined amount of the chip-shaped resin and the granulated product of the powdery additive are charged into the blender 21. The blender 21 is a rotary mixer in which the contents are mixed by rotating the container 21b about the shaft 21a. In this case, for example, the number of rotations is 20 to 30 times / minute, and the mixing time is 10 to 30 minutes. Rotate about to mix the contents. Further, a baffle plate or the like for improving the mixing efficiency may be provided in the blender 21.
[0016]
After rotating the blender 21 for a predetermined time, the discharge port formed in the blender 21 is opened to drop the content toward the hopper 22, and the content is poured from the hopper 22 into the barrel 13 heated to a predetermined temperature. I will do it. Here, the falling speed (discharge amount) of the contents from the blender 21 to the hopper 22 depends on the capacity of the container 21b and the like, but is usually 180 to 350 kg / hr.
Then, by the action of the two screws 24 in the barrel 23, the chip-shaped resin and the granulated material of the powdery additive are extruded from the round die 25 while being melted and kneaded.
As a result, a strand-shaped resin composition using the chip-shaped resin and the powdery additive as raw materials is extruded from the round die 25, and is appropriately cut to obtain a resin composition chip.
[0017]
As described above, by adding a powdery additive having a bulk specific gravity of less than 0.19 g / ml and particularly having a large air bite amount to a bulk specific gravity in advance and forming a granulated product, the powdery additive and the chip-like resin can be mixed with each other. When the mixture is dropped into the hopper 22 and charged into the hopper 22, there is no large difference in the drop speed between the chip-shaped resin and the granulated product of the powdery additive. The mixture is introduced into the barrel 24 as it is. Therefore, a resin composition having a uniform composition can be obtained throughout the extrusion process.
[0018]
Here, there is no particular limitation on how much the bulk specific gravity of the powdery additive is increased by the bulk specific gravity increasing treatment, and the bulk specific gravity is increased so as to be preferably 0.19 g / ml or more. The treatment may be carried out. For example, when the powdery additive is a fine powder of silicon dioxide having a bulk specific gravity of 0.07 to 0.18 g / ml, the amount is about 0.24 to 0.32 g / ml. Within such a range, there is no large difference in the drop speed when the chip-shaped resin is dropped from the blender 21 to the hopper 22, and the bulk specific gravity increasing process can be performed without requiring large energy.
[0019]
As described above, according to such a method for producing a resin composition, when a chip-like resin and a powdery additive having a bulk specific gravity of less than 0.19 g / ml are mixed to produce a resin composition, Since the powdery additive is mixed after being subjected to the bulk specific gravity increasing treatment, the chip-shaped resin and the granulated product of the powdery additive subjected to the bulk specific gravity increasing treatment are integrally dropped from the blender 21 to the hopper 22, and the It is put into the barrel 23 of the extruder 20. As a result, the composition of the resin composition extruded from the round die 25 does not differ between the initial stage and the late stage of the extrusion process, and a homogeneous resin composition is obtained throughout the extrusion process. Therefore, it is possible to adopt a masterbatch method or an after-blending method which increases production costs, mix foreign substances such as a spreading agent, and furthermore, provide a stable resin composition of a stable quality and composition without providing a plurality of hoppers. Products can be manufactured at low cost.
In the above example, the method for producing the resin composition using the twin-screw extruder 20 shown in FIG. 2 has been described, but the twin-screw extruder provided with such a round die 25 is used as an apparatus. It is not limited to the extruder 20, but may be a single-screw extruder or a multi-screw extruder, and the shape of the die is not limited.
[0020]
In addition, during the production of the resin composition, as for powdery additives having a bulk specific gravity of less than 0.19 g / ml, the bulk specific gravity is increased to 0.19 g / ml as long as the additive is mixed with the chip-shaped resin. The above powdery additives may be directly mixed together, or a powdery additive other than plate-like or granular may be further mixed together with the fibrous filler such as carbon fiber and glass fiber. Good. In addition, the fibrous filler may be added through a charging port (not shown in FIG. 2) provided on the side of the barrel 23 during melting and kneading.
Examples of such additives include quartz, talc, kaolin, mica, clay, hydrotalcite, mica, graphite, glass beads, calcium carbonate, calcium sulfate, barium carbonate, barium sulfate, magnesium carbonate, magnesium sulfate, and silicate. Examples of fine powder fillers such as calcium, titanium oxide, zinc oxide, magnesium oxide, silicon oxide, calcium titanate, magnesium titanate, barium titanate, as well as lubricants, flame retardants, antistatic agents, coloring agents, antibacterial agents, etc. One or more of these can be blended as needed.
[0021]
【Example】
Hereinafter, the present invention will be described specifically with reference to examples.
[Example 1]
A fine powder of silicon dioxide (Tokuseal, manufactured by Tokuyama Corporation, bulk specific gravity: 0.17 g / ml) was mixed with a dry compression granulation system roller compactor RCP-100 (manufactured by Kurimoto Iron and Steel Works, Ltd.) (granulation conditions, 0.06 to 0). 0.07 MPa and a roll pressure of 6.5 tons) to obtain a granulated product having a bulk specific gravity of 0.24 to 0.32 g / ml.
Next, 100 parts by mass of chip-shaped PBT (Tuffpet N1300 manufactured by Mitsubishi Rayon Co., Ltd., shape: cylindrical shape having a diameter of 2.5 mm) and 5 parts by mass of the granulated silicon dioxide powder obtained above are shown in FIG. It was charged into the blender 11 of the screw extruder 20.
[0022]
Then, after blending the contents by rotating the blender 21 at a rate of 20 times / minute for 30 minutes, the discharge port of the blender 21 is opened, and the contents are dropped into the hopper 22 under the condition of about 300 kg / hr. The resin composition was put into the barrel 23 from the hopper 22, melted and kneaded, and the resin composition was extruded from the round die 25 and cut into chips.
Extrusion conditions are as follows.
Diameter of round die 25: 185mmφ
L / D = 30
Temperature of barrel 23: 230 ° C
Extrusion speed: 300 kg / Hr
[0023]
Early in the extrusion process (5 minutes after the start of extrusion), in the middle of the extrusion process (30 minutes from the start of the extrusion). Minutes), and the content of silicon dioxide in the resin composition obtained in the later stage of the extrusion process (after 60 minutes from the start of extrusion) was analyzed by an incineration method, and the content was 4.5% by mass. 4.8% by mass and 4.7% by mass, suggesting that no composition unevenness occurred during the extrusion process.
[0024]
[Example 2]
In the same manner as in Example 1, except that the addition amount of the granulated silicon dioxide was changed from 5 parts by mass to 10 parts by mass, the resultant was cut into chips.
The resin composition obtained in the initial stage of the extrusion process (after 5 minutes from the start of extrusion), in the middle stage of the extrusion process (after 30 minutes from the start of extrusion), and in the late stage of the extrusion process (after 60 minutes from the start of extrusion). When the content of silicon dioxide was analyzed by the incineration method, the content was 8.9% by mass, 9.2% by mass, and 9.0% by mass, respectively, and no composition unevenness occurred throughout the extrusion process. Was suggested.
[0025]
[Comparative Example 1]
The resin composition was extruded from the round die 15 in the same manner as in Example 1 except that Tokuseal manufactured by Tokuyama Corporation and bulk density 0.17 g / ml were used as the fine powder of silicon dioxide. Since the obtained resin composition had a high content of silicon dioxide, it was broken many times during extrusion, and could not be formed into a continuous strand.
In addition, the resin composition obtained in the initial stage of the extrusion process (after 5 minutes from the start of extrusion), the middle stage of the extrusion process (after 30 minutes from the start of extrusion), and the late stage of the extrusion process (after 60 minutes from the start of extrusion), respectively. When the content of silicon dioxide was analyzed by an incineration method, the content was 3.2% by mass, 3.5% by mass, and 6.2% by mass, respectively. The amount was increasing.
[0026]
【The invention's effect】
As described above, according to the method for producing a resin composition of the present invention, when a chip-like resin and a powdery additive having a bulk specific gravity of less than 0.19 g / ml are mixed to produce a resin composition, Since the powdery additive is mixed after the bulk specific gravity increasing treatment, for example, the resin and the powdery additive are put into an extruder from one hopper and melted and kneaded to produce a resin composition. Also, the composition of the resin composition does not differ between the initial stage and the late stage of the extrusion process, and a homogeneous resin composition can be obtained throughout the extrusion process. Therefore, according to the present invention, a resin composition having stable quality and composition can be produced at low cost.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an example of a dry granulator used for a bulk specific gravity increasing process.
FIG. 2 is a partial cross-sectional view showing one example of an extruder used for producing a resin composition.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Dry granulator 11 Hopper 11a Screw 12 Transfer part 12a Screw 13 Roll 14 Crusher 15 Granulator 16 Supply part 20 Twin screw extruder 21 Blender 21a Shaft 21b Container 22 Hopper 23 Barrel 24 Screw 25 Round die

Claims (5)

When producing a resin composition by mixing a chip-shaped resin and a powdery additive having a bulk specific gravity of less than 0.19 g / ml, mixing the powdery additive after increasing the bulk specific gravity is performed. A method for producing a resin composition. 2. The resin composition according to claim 1, wherein the chip-shaped resin and the powdery additive are preliminarily mixed, charged into an extruder from one input port, melted and kneaded to produce the resin composition. A method for producing a resin composition. The method for producing a resin composition according to claim 1, wherein the bulk density increasing treatment granulates the powdery additive. The method for producing a resin composition according to any one of claims 1 to 3, wherein the chip-shaped resin is a polyester-based resin. The method for producing a resin composition according to any one of claims 1 to 4, wherein the powdery additive contains at least silicon dioxide.

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