JP2004263127A - 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 a powdery additive. <P>SOLUTION: In the manufacture of the resin composition by mixing the chip-like resin with the powdery additive, a crushed matter obtained by crushing a part of the chip-like resin in advance is mixed. Preferably, 3-50 mass% of the chip-like resin is crushed into crushed matter. The manufacturing method is suitable when the chip-like resin is a polyester resin or when the powdery additive contains at least a colorant. <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 10 as shown in FIG. 1 may be used.
In the twin-screw extruder 10, a predetermined amount of chip-shaped PBT and a powdery additive are charged, and a rotary blender 11 in which these are mixed for a predetermined time, and a mixture mixed by the blender 11 are charged by dropping. And one hopper 12. The mixture put into the hopper 12 enters the barrel 13, is melted and kneaded in the barrel 13, and is extruded from the round die 15 by two screws 14. The strand-shaped resin composition extruded from the round die 15 is appropriately cut into a resin composition chip, which is used for various moldings.
[0004]
[Patent Document 1]
JP-A-7-53855 [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. For example, when the powdery additive contains a coloring agent, the resin composition obtained in the early stage of the extrusion process has a light color, and the resin composition obtained in the late stage of the extrusion process has a dark color. There has occurred. In addition, particularly in the case of a coloring agent, the addition amount is often extremely small relative to the chip-shaped PBT, so that the coloring agent tends to be particularly inhomogeneous.
[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, and when a chip-like resin and a powdery additive are mixed to produce a resin composition, a spreading agent may be used, or a masterbatch method or an after-blending method may be used. 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 method or providing a plurality of hoppers.
[0009]
[Means for Solving the Problems]
In the method for producing a resin composition of the present invention, when producing a resin composition by mixing a chip-shaped resin and a powdery additive, a part of the chip-shaped resin is mixed as a pulverized product which has been previously pulverized. It is characterized by the following.
It is preferable to pulverize 3 to 50% by mass of the chip resin.
The production method of the present invention is suitable when the chip-shaped resin is a polyester-based resin and the powdery additive contains at least a colorant.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
The method for producing a resin composition of the present invention includes mixing a chip-shaped resin and a powdery additive to produce a resin composition, and mixing a part of the chip-shaped resin as a previously pulverized product. It is.
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 chip-like.
[0012]
As the powdery additive to be mixed with the chip-like resin, the average particle diameter measured by a laser diffraction method is within a range of 1000 μm or less, and as long as the additive is usually used as a resin additive, there are no restrictions. Absent.
Examples of the powdery additives include quartz, talc, kaolin, mica, clay, hydrotalcite, mica, graphite, glass beads, calcium carbonate, calcium sulfate, barium carbonate, barium sulfate, magnesium carbonate, magnesium sulfate, calcium silicate Fine powder fillers such as titanium oxide, zinc oxide, magnesium oxide, silicon oxide, calcium titanate, magnesium titanate, barium titanate; fibrous reinforcing agents such as carbon fiber, glass fiber, aramid fiber; paraffin wax, polyethylene wax Lubricating agents such as stearic acid and calcium stearate; flame retardants such as halogen compounds and phosphorus compounds; antistatic agents such as alkyl sulfonates and alkyl benzene sulfonates; coloring agents such as carbon black, titanium oxide, red iron oxide and ultramarine blue; Can be exemplified such as antibacterial agents such as systems inorganic antibacterial agent, the use of only one kind of these may be used or two or more kinds.
The shape of the powdery additive is not limited as long as the average particle diameter measured by the above method is within the above range, and may be, for example, plate-like.
In addition, among the powdery additives, the colorant is usually added to the chip-shaped resin in a small amount of 2 parts by mass or less based on 100 parts by mass of the chip-shaped resin. Therefore, it is particularly effective to mix with the chip-shaped resin.
[0013]
When mixing such a chip-shaped resin and a powdery additive to produce a resin composition, a part of the chip-shaped resin is crushed in advance to obtain a crushed product.
The method of pulverization is not particularly limited, and examples thereof include a method of pulverizing with a pulverizer such as a high-speed rotary impact-shear mill, a roll mill, a medium mill, a pneumatic mill, a shear friction mill, or the like. By these methods, it is preferable to grind to a sieve of 20 mesh or less. Preferably, it is 28 mesh or less, and more preferably less than 32 mesh. If the mesh size exceeds 20 mesh, the effects described below by pulverization may not be sufficiently obtained.
[0014]
When a resin composition is produced by mixing the chip-shaped resin, which is partly pulverized, with the powdery additive, a mixer or the like for mixing these while melting them may be used as appropriate. Here, a method using the twin-screw extruder 10 of FIG. 1 will be exemplified and specifically described.
First, predetermined amounts of a pulverized chip resin, an unpulverized chip resin, and a powdery additive are charged into the blender 11. The blender 11 is a rotary mixer in which the contents are mixed by rotating the container 11b about the axis 11a. 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 11.
[0015]
After rotating the blender 11 for a predetermined time, the discharge port formed in the blender 11 is opened to drop the contents toward the hopper 12, and the contents are charged from the hopper 12 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 11 to the hopper 12 depends on the capacity of the container 11b and the like, but is usually 180 to 350 kg / hr.
Then, by the action of the two screws 14 in the barrel 13, the pulverized product of the chip-shaped resin, the unpulverized chip-shaped resin and the powdery additive are melted and kneaded, and are extruded from the round die 15.
As a result, a strand-shaped resin composition composed of a chip-shaped resin and a powdery additive is extruded from the round die 15 and is appropriately cut to obtain a resin composition chip.
[0016]
By previously grinding a part of the chip-shaped resin, the unpulverized chip-shaped resin, the pulverized material and the powdery additive are uniformly mixed at the time of mixing in the blender 11, and as a result, It is conceivable that the pulverized chip-shaped resin, the pulverized material and the powdery additive fall together from the blender 11 to the hopper 12. Accordingly, a resin composition having a uniform composition can be obtained throughout the extrusion process without a difference in drop speed between the uncrushed chip-shaped resin and the pulverized product and the powdery additive. For example, when the powdery additive contains a colorant, the degree of coloring is the same between the resin composition obtained in the early stage of the extrusion process and the resin composition obtained in the late stage of the extrusion process, and color unevenness occurs. Does not occur.
[0017]
Of the chip-shaped resin, the ratio of the powdered material to be crushed in advance can be appropriately adjusted according to the amount of the powdered additive to be mixed. For example, the powdered additive is added to 100 parts by mass of the chip-shaped resin. Is added in the range of 0.2 to 50 parts by mass, of 100 parts by mass of the chip-shaped resin, 3 to 50% by mass, preferably 5 to 25% by mass is pulverized into a pulverized product, and the rest is chipped. Leave in shape. If the proportion of the pulverized material is less than 3% by mass, the effect of pulverizing a part of the chip-shaped resin may not be sufficiently exhibited, and a homogeneous resin composition may not be obtained. On the other hand, if the ratio of the pulverized material exceeds 50% by mass, the ratio of the pulverized material to the unpulverized chip resin is too large, and the pulverized material and the powdery additive are mixed by the unpulverized chip resin in the blender 11. It is considered that the stirring effect of stirring is less likely to be exhibited.
[0018]
As described above, according to such a method for producing a resin composition, when a chip-shaped resin and a powdery additive are mixed to produce a resin composition, a part of the chip-shaped resin is pulverized in advance. As a result, the chip-shaped resin and the powdery additive fall integrally from the blender 11 to the hopper 12 and are charged into the barrel 13 of the twin-screw extruder 10. As a result, the composition of the resin composition extruded from the round die 15 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, without providing a plurality of hoppers 12, a resin of stable quality and composition. The composition can be manufactured inexpensively.
In the above example, the method for producing the resin composition using the twin-screw extruder 10 shown in FIG. 1 has been described, but the apparatus used is a twin-screw extruder provided with such a round die 15. The extruder is not limited to the extruder 10, but may be a single-screw extruder or a multi-screw extruder, and the shape of the die is not limited.
[0019]
【Example】
Hereinafter, the present invention will be described specifically with reference to examples.
[Example 1]
A chip-shaped PBT (Tuffpet N1300 manufactured by Mitsubishi Rayon Co., Ltd., shape: cylindrical shape having a diameter of 2.5 mm) was prepared, and 5% by mass thereof was pulverized with a turbo pulverizer under the conditions of 1.15 to 1.2 atm. The sieving degree of the obtained PBT crushed product is 32 mesh on: 12.1%, 42 mesh on: 42.1%, 60 mesh on: 30.8%, 100 mesh on: 13.6%, 150 mesh on: 1.1%. The measurement was performed using an electromagnetic vibration sieving device Sieve Shaker Octagon Digital (Seishin Enterprise) under the conditions of measurement intensity: level 9, and measurement time: 10 minutes.
100 parts by mass of the mixture of the unmilled chip-shaped PBT and the ground PBT and the following powdery additives were charged into the blender 11 of the extruder 10 in FIG.
Coloring agent (No. 1900, manufactured by Daiichi Kasei Kogyo Co., Ltd., average particle size: 1 to 3 μm); 1 part by mass mica (Mica powder, 325 manufactured by Hayashi Kasei; average particle size: 50 μm); 20 parts by mass. Average of each powdery additive The particle size was measured by a laser diffraction method.
Then, after blending the contents by rotating the blender 11 at 20 times / min for 20 minutes, the discharge port of the blender 11 is opened, and the contents are dropped into the hopper 12 under the condition of about 250 kg / hr. The resin composition was put into the barrel 13 from the hopper 12, melted and kneaded, and the resin composition was extruded from the round die 15 and cut into chips.
Extrusion conditions are as follows.
Diameter of round die 15: 185mmφ
L / D = 30
Temperature of barrel 13: 230 ° C
Extrusion speed: 250 kg / Hr
[0020]
The resin compositions obtained at the beginning of the extrusion process (after 5 minutes from the start of extrusion), at the middle of the extrusion process (after 30 minutes from the start of extrusion), and at the end of the extrusion process (after 60 minutes from the start of extrusion) are visually compared. As a result, in all cases, the degree of coloring was the same, and color unevenness did not occur throughout the extrusion process.
[0021]
[Example 2]
The resin composition was extruded from the round die 15 and cut into chips in the same manner as in Example 1 except that the ratio of pulverization (the ratio of the pulverized material) was set to 10% by mass of the whole chip-shaped PBT.
The resin compositions obtained at the beginning of the extrusion step (after 5 minutes from the start of extrusion), at the middle of the extrusion step (after 30 minutes from the start of extrusion), and at the end of the extrusion step (after 60 minutes from the start of extrusion) are visually observed. As a result, in all cases, the degree of coloring was the same, and color unevenness did not occur throughout the extrusion process.
[0022]
[Example 3]
The resin composition was extruded from the round die 15 and cut into chips in the same manner as in Example 1 except that the pulverization ratio (ratio of the pulverized material) was set to 20% by mass of the whole chip-shaped PBT.
The resin compositions obtained at the beginning of the extrusion process (after 5 minutes from the start of extrusion), at the middle of the extrusion process (after 30 minutes from the start of extrusion), and at the end of the extrusion process (after 60 minutes from the start of extrusion) are visually compared. As a result, in all cases, the degree of coloring was the same, and color unevenness did not occur throughout the extrusion process.
[0023]
[Comparative Example 1]
The resin composition was extruded from the round die 15 and cut into chips in the same manner as in Example 1 except that the chip-shaped PBT was used as it was without grinding.
Then, the resin composition obtained early in the extrusion process (5 minutes after the start of extrusion) was visually compared with the resin composition obtained late in the extrusion process (60 minutes after the start of extrusion). The color of the resin composition obtained at an early stage was light, and the color of the resin composition obtained at a later stage was dark, and color unevenness occurred. Therefore, a step of after-blending these and homogenizing them is required.
[0024]
[Comparative Example 2]
The resin composition was extruded from the round die 15 and cut into chips in the same manner as in Example 1 except that the pulverized PBT used in Example 1 was used as the PBT.
Then, the resin composition obtained early in the extrusion process (5 minutes after the start of extrusion) was visually compared with the resin composition obtained late in the extrusion process (60 minutes after the start of extrusion). The color of the resin composition obtained at an early stage was light, and the color of the resin composition obtained at a later stage was dark, and color unevenness occurred. Therefore, a step of after-blending these and homogenizing them is required.
[0025]
【The invention's effect】
As described above, according to the method for producing a resin composition of the present invention, when a chip-shaped resin and a powdery additive are mixed to produce a resin composition, a part of the chip-shaped resin is pulverized in advance. Therefore, for example, even when a resin and a powdery additive are put into an extruder from one hopper and melted and kneaded to produce a resin composition, the composition of the resin composition is reduced in the extrusion process. There is no difference between the initial stage and the late stage, and a homogeneous resin composition can be obtained through 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 partial cross-sectional view showing an example of an extruder used for producing a resin composition.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Twin-screw extruder 11 Blender 11a Shaft 11b Container 12 Hopper 13 Barrel 14 Screw 15 Round die

Claims (4)

A method for producing a resin composition, comprising: mixing a chip-shaped resin with a powdery additive to produce a resin composition, wherein a part of the chip-shaped resin is mixed as a preliminarily crushed product. . The method for producing a resin composition according to claim 1, wherein 3 to 50% by mass of the chip-shaped resin is crushed. The method for producing a resin composition according to claim 1, 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 3, wherein the powdery additive contains at least a coloring agent.

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