JPH06238655A - Production of thermoplastic resin composition - Google Patents

Abstract

PURPOSE:To reduce the cutting of a strand or the generation of eye muscus and to enhance production efficiency by holding the temp. of a resin after the supply of a filler to specific temp. or higher. CONSTITUTION:A thermoplastic resin is supplied from the first feeder 1 of a screw extruder to be melted and a filler is supplied from a second feeder 2 to be kneaded with the molten resin so that the content of the filler is set to 15wt.% or more. In this case, the temp. of the resin after the supply of the filler is held to (Tm-40 deg.C or higher (Tm; the m.p. of the resin). As the filler, a reinforcing material such as a glass fiber or a carbon fiber and a filler such as talc, kaolin or silica are designated. As the thermoplastic resin, engineering plastic such as polyamide or polyester is pref. The thermoplastic resin is supplied from the first feeder 1 and melted in the zone 3 before the second feeder 2 by high shearing force.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a resin composition in which a relatively large amount of a filler such as glass fiber is mixed with a thermoplastic resin by extrusion melt kneading. More specifically, the present invention relates to a method for producing a filler-containing thermoplastic resin composition by extrusion melt-kneading that suppresses strand breaks and eye blemishes.

[0002]

2. Description of the Related Art It is well known to mix a filler such as glass fiber with a thermoplastic resin, and one of the mixing methods is extrusion melt kneading. Generally, in extrusion melt-kneading, a thermoplastic resin is supplied from the first feeder, a high shearing force is applied by a screw element such as a kneading disk or reverse flight to melt the resin, and then a filler is supplied from the second feeder. Then, the screw element is again made into a kneading disk or a reverse flight to apply a high shearing force and kneading.

Usually, the temperature of the resin supplied from the first feeder is about Tm to (Tm + 10) ° C. (Tm is the melting point of the resin), and when a large amount of filler is supplied from the second feeder, The resin temperature is temporarily (Tm-
50) to (Tm-60) ° C. When a shearing force is further applied to this for kneading, the temperature of the resin rapidly rises due to heat generation.

[0004]

Conventionally, in such extrusion melt-kneading, when a relatively large amount of filler is melt-kneaded with a thermoplastic resin, strand breaks and black foreign matters (commonly called eye dents) generated are removed. There were many outages due to the disaster, which was an obstacle to improving productivity.

[0005]

Means for Solving the Problems As a result of intensive studies on the above problems, the present inventors have found that a large decrease in the resin temperature after the supply of the filler is a cause of strand breaks and eye blemishes, and thus reached the present invention. did. That is,
The gist of the present invention is to provide a thermoplastic resin having a filler content of 15% by weight or more, which comprises supplying a thermoplastic resin from a first feeder of a screw extruder, melting, and then supplying a filler from a second feeder to melt-knead. In the method for producing a resin composition, the resin temperature after supplying the filler is set to (Tm-4
0) C. or higher (Tm is the melting point of the resin) is maintained, which is a method for producing a thermoplastic resin composition.

The present invention will be described in detail below. The resin composition targeted by the present invention is a resin composition obtained by mixing 15% by weight or more of a filler with a thermoplastic resin. In the conventional method, when the filler was added in an amount of 15% by weight or more, the resin temperature immediately after the addition was large, which was a cause of strand breakage and formation of crevices. The present invention is particularly effective when the content of the filler is 30% by weight or more.

Examples of the filler used in the present invention include reinforcing agents such as glass fiber and carbon fiber, and fillers such as talc, kaolin, silica and alumina. It is particularly effective to apply the present invention to glass fibers. Examples of the thermoplastic resin used in the present invention include resins used as engineering plastics, and specifically, polyamide, polyester, polyphenylene sulfide, etc. are preferably used.

As the polyamide, a lactam having three or more members, a polymerizable ω-amino acid, or a polyamide obtained by polycondensation of a dibasic acid and a diamine is used. Specifically, nylon-4,6,7,8,11,12,6.
6, 6.9, 6.10, 6.11, 6.12, 6T, 6
Examples include polyamides such as /6.6, 6/12 and 6 / 6T.

Examples of polyesters include polyethylene terephthalate, polyethylene naphthalate, polypropylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polycyclohexane dimethylene terephthalate, and poly (ethylene terephthalate / ethylene isophthalate) copolymers.

In the present invention, the effect is particularly remarkable when the aliphatic polyamide is used, and among them, nylon-6 is preferable. As the extruder used in the present invention, a screw extruder having a known side feeder such as a single-screw extruder, a twin-screw co-rotating screw extruder, or a twin-screw counter-rotating screw extruder is used. Generally, in a screw extruder, the main factors that increase the resin temperature in the screw extruder are heat conduction from the barrel and heat generation due to the shearing force applied to the resin. It is controlled by the number of rotations.

In the present invention, the thermoplastic resin is supplied from the first feeder and melted by applying a high shearing force to the second feeder. The residence time up to the second feeder can be appropriately determined according to a conventional method, usually 10 to 120 sec.
In addition, the maximum resin temperature before supplying the filler is usually preferably in the range of (Tm + 10) to (Tm + 40) ° C.

In the present invention, the filler is then supplied from the second feeder, at which time the resin temperature temporarily drops. The feature of the present invention is that the resin temperature after the addition of the filler is (Tm-40) ° C, preferably (Tm-30) ° C.
By maintaining the temperature above, that is, by preventing the resin temperature from falling below this temperature, it is possible to suppress the occurrence of strand breaks and eye blemishes.

Specifically, since nylon-6 has a melting point of about 225 ° C., the resin temperature after the addition of the filler is 185 ° C. or higher, preferably 195 ° C. or higher. In the case of nylon-66, since the Tm is about 265 ° C, the resin temperature after the filler addition is 225 ° C or higher, preferably 23 ° C.
5 ℃ or more. In the case of polybutylene terephthalate, since the Tm is about 225 ° C, the resin temperature after adding the filler is 185 ° C or higher, preferably 195 ° C or higher. Tm is about 26 for polyethylene terephthalate
Since the temperature is 0 ° C, the resin temperature after adding the filler should be 220 ° C.
Or higher, preferably 230 ° C. or higher. Since Tm of polyphenylene sulfide is about 283 ° C, the resin temperature after the filler addition is 243 ° C or higher, preferably 253 ° C.
That is all.

In order to keep the minimum resin temperature after the addition of the filler within the above range, it is usually necessary to set the resin temperature immediately before the second feeder to a higher value. Specifically, the barrel set temperature up to the second feeder is set. And a method of increasing shearing force by increasing the screw rotation speed. Further, the minimum temperature of the resin can be set within the above range by heating the filler to be added in advance.

On the other hand, when the resin is supplied from the first feeder and melted and kneaded, and then the filler is further supplied from the second feeder as it is and the mixture is kneaded by applying a high shearing force, the maximum resin temperature becomes higher than the decomposition temperature of the resin. It is necessary to adjust the barrel temperature of the entire extruder, the screw configuration, and the rotation speed so as not to occur. On the other hand, conventionally, the barrel set temperature is set to a temperature higher than the melting point of the resin, and the rotation speed of the screw or the like is controlled so that the resin temperature does not rise too much.

However, the resin temperature after the filler is supplied is set to Tm.
When the temperature is -40 ° C or higher, when the resin and the filler are kneaded with a high shearing force, heat is generated, and thus the resin temperature may be too high in the conventional method. The maximum allowable resin temperature depends on the type of resin and residence time,
Generally, if the temperature exceeds (Tm + 150) ° C., the amount of resin decomposed increases, which is not preferable.

Specifically, taking nylon-6 as an example,
Nylon-6 decomposes rapidly above 350 ° C. Therefore, in the case of nylon-6, the resin temperature is 35
It is necessary to shorten the time above 0 ° C as much as possible. Therefore, in the second invention of the present application, it is necessary to prevent the resin temperature from becoming too high by forcibly cooling the corresponding barrel after the supply of the filler after the second feeder to remove heat. The method of forced cooling of the barrel is not particularly limited as long as it is a method known to those skilled in the art, but water cooling is preferable. Further, the cooling temperature at this time is usually preferably set such that the barrel set temperature is Tm or lower.

Conventionally, the barrel set temperature of the extruder has generally been set to be equal to or higher than the melting point (Tm) of the resin. That is, when the barrel set temperature is Tm or lower, the resin may be solidified on the inner surface of the barrel, and thus it is considered to be inappropriate.
However, as a result of intensive studies by the present inventors, since the resin temperature is high due to shearing force, even if the barrel set temperature after the second feeder is set to Tm or less, the problem of solidification does not occur, and rather the resin maximum temperature is It was found to be preferable because it has the effect of lowering it.

Here, the barrel set temperature is the internal temperature of the barrel heating heater. Usually, the heater for barrel heating is 5-10 mm from the outer surface of the barrel for temperature control.
The temperature inside the heater is separated by a thermocouple.
Specifically, taking nylon-6 (Tm = about 225 ° C.) as an example, the barrel set temperature after the second feeder is 200 ° C.
Hereafter, it is particularly preferably set to 150 to 100 ° C. Second
The residence time from the feeder to the extruder outlet can be arbitrarily determined according to a conventional method, and is usually 10 to 120 sec.
It is a degree.

[0020]

EXAMPLES The present invention will now be described in detail with reference to examples, but the present invention is not limited to the examples as long as the gist thereof is not exceeded. Examples 1-2, Comparative Examples 1-2 Nylon-6 (Novamid 101, manufactured by Mitsubishi Kasei Co., Ltd.)
5: Novamid indicates an example of producing a resin composition in which 45% by weight of glass fiber (length 3 mm, diameter 13 μm) is added to a registered trademark: melting point 225 ° C.).

As an extruder, the total length is 2240 mm, L / D2
5.2 (up to 1080mm side feeder) twin-screw extruder (Wnerner, ZSK-90M)
240-2) was used. FIG. 1 shows a schematic view of this twin-screw extruder. In the figure, 1 represents a first feeder and 2 represents a second feeder. Table 1 shows the set temperature of the barrel (up to the second feeder is the first half, after the second feeder is the second half), screw rotation speed, resin minimum temperature after glass fiber addition, resin heat generation maximum temperature, resin outlet temperature And 2
The number of strand breaks per 4 hours is shown.

Comparative Example 1 is a case where the production was conducted under conventional manufacturing conditions. In Example 1, the minimum temperature of the resin after the glass fiber addition was increased by increasing the barrel set temperature in the first half and increasing the screw rotation speed to increase the shearing force, and further water cooling in the latter half to set the barrel. In this example, the temperature is 100 ° C. Example 2 is an example in which the screw rotation speed was increased and the resin minimum temperature was increased, but water cooling was not performed.

In Comparative Example 2, water cooling was performed in the latter half, but the screw rotation speed was not increased and the minimum resin temperature was Tm-40.
As can be seen from these, it is important to raise the minimum resin temperature in order to prevent strand breakage and the like, and cooling the latter half is more effective.

[0024]

[Table 1]

[0025]

According to the method of the present invention, when a resin composition having a high filler content is extrusion-melted and kneaded, strand breaks and eye crevices are reduced, and production efficiency is significantly improved.

[Brief description of drawings]

FIG. 1 is a view of a twin-screw extruder used in Examples.

[Explanation of symbols]

 1 1st feeder 2 2nd feeder 3 Zone where shearing force is applied A Barrel in the first half up to the 2nd feeder B Barrel in the latter half after the 2nd feeder

Claims (2)

[Claims] 1. A thermoplastic resin composition having a filler content of 15% by weight or more, which comprises supplying a thermoplastic resin from a first feeder of a screw extruder, melting it, and then supplying a filler from a second feeder to melt and knead the filler. In the manufacturing method of the product, the resin temperature after the filler is supplied is (Tm-40) ° C.
A method for producing a thermoplastic resin composition, which is maintained at the above (Tm is the melting point of the thermoplastic resin). 2. A thermoplastic resin composition having a filler content of 15% by weight or more, which comprises supplying a thermoplastic resin from a first feeder of a screw extruder, melting the mixture, and then supplying a filler from a second feeder to melt and knead the mixture. In the manufacturing method of the product, the resin temperature after the filler is supplied is (Tm-40) ° C.
A method for producing a thermoplastic resin composition, characterized in that the above (Tm is the melting point of the thermoplastic resin) is maintained and the barrels after the second feeder are forcibly cooled.