JP7426451B1 - Method for producing glass fiber reinforced polyamide resin composition - Google Patents

Abstract

The present invention provides a method for manufacturing a glass fiber-reinforced polyamide resin composition containing a high concentration of glass fiber into pellets that suppresses strand breakage, enables continuous and stable production, and maintains a good pellet shape. [Solution] (A) 20 to 70% by mass of polyamide resin, (B) 10 to 75% by mass of glass fiber, (C) 0 to 40% by mass of other reinforcing materials, and (D) other polymers or additives. A method for producing a glass fiber-reinforced polyamide resin composition consisting of 0 to 30% by mass (total of each component is 100% by mass) using a twin-screw extruder, the method comprising: When extruding the strand from the horizontal flat die 25, the temperature of the strand from the center die hole 31 of the horizontal flat die 25 is 310°C to 360°C, and the resin pressure inside the die when it comes out of the die is 2.0°C. A method for producing a glass fiber reinforced polyamide resin composition, which comprises extruding a strand to a pressure of ~8.5 MPa. [Selection diagram] Figure 2

Description

The present invention relates to a method for producing a glass fiber-reinforced polyamide resin composition, and more specifically, a method for producing a glass fiber-reinforced polyamide resin composition containing a high concentration of glass fibers and other reinforcing materials into strands using a twin-screw extruder. The present invention relates to a method for producing pellets that suppresses breakage, enables continuous and stable production, has high productivity, and maintains a good pellet shape.

Polyamide resins represented by nylon MXD6, nylon 6, nylon 66, etc. are widely used for injection molding, various mechanical parts, automobile parts, and the like. In particular, glass fiber-reinforced polyamide resin compositions containing a high content of glass fibers have excellent mechanical strength, heat resistance, chemical resistance, etc., and are used as parts in the automobile field, mechanical equipment field, etc.

Patent Document 1 describes (1) a polyamide resin (A) composed of an aliphatic polyamide (a1) and a polyamide containing an aromatic component (a2), and a polyamide resin (A) having a cross-sectional area of 1.5 to 5.0×10 ^−6. A glass fiber-reinforced polyamide resin composition containing 2 cm ² of glass fiber (B), wherein the weight ratio of polyamide resin (A) to glass fiber (B) (A):(B) is 20:80 to 35: A glass fiber reinforced polyamide resin composition No. 65 is described.

However, polyamide resin compositions containing high concentrations of glass fibers and other reinforcing materials are susceptible to strand breakage when extruded from a die during production using a twin-screw extruder. When a strand breaks, it contacts an adjacent strand, causing the adjacent strand to also break. Then, the work of reinserting the broken strands into the pelletizer and the work of straightening the strands occur, resulting in a significant drop in productivity. Furthermore, when the broken strands are put into a pelletizer, they overlap each other, disrupting the flow of the strands, and making long pellets more likely to occur. In addition, the higher the concentration, the more difficult the strands are to cut, the cross-section of the pellets is not sharp, and more chips are generated. This tendency becomes more pronounced as the concentration of glass fiber and other reinforcing materials increases. Long pellets and chips are likely to have poor plasticization during molding with an injection molding machine, resulting in longer weighing times, stopping the injection molding machine, and reducing productivity. In particular, this phenomenon becomes remarkable when the content of glass fibers and other reinforcing materials exceeds 30% by mass, when it exceeds 40% by mass, and especially when it exceeds 50% by mass.

International publication WO2014/171363

The problem (object) of the present invention is to suppress the breakage of strands coming out of a die when producing a glass fiber reinforced polyamide resin composition containing a high concentration of glass fiber and other reinforcing materials using a twin screw extruder. , to enable continuous and stable production and to suppress the generation of long pellets.

As a result of intensive studies to solve the above problems, the present inventor produced a polyamide resin composition containing a high content of 10 to 75% by mass of glass fiber and 0 to 40% by mass of other reinforcing materials using a twin-screw extruder. In this case, the resin composition has a high viscosity, but the shear viscosity is 400 to 2000 Pa・s (280°C, 91/sec), the strand temperature is a specific temperature, and the die at that time is We have discovered that by controlling the pressure within a specific range, strand breakage can be suppressed, continuous stable production can be achieved, and the generation of long pellets can be significantly suppressed, and the present invention has been achieved.
In addition, at that time, it is preferable that the temperature of the die holder is in the temperature range of 250 to 340°C, and that the temperature of the strand from the die hole at the end of the flat die is the same as the temperature of the strand from the die hole at the center of the flat die. It has been found that it is preferable to lower the temperature by 4 to 14°C.
The present invention relates to the following method for producing a glass fiber reinforced polyamide resin composition.

1. (A) 20-70% by weight of polyamide resin, (B) 10-75% by weight of glass fiber, (C) 0-40% by weight of other reinforcing materials, and (D) 0-30% by weight of other polymers or additives. (The total of each component is 100% by mass) A method for producing a glass fiber reinforced polyamide resin composition using a twin screw extruder, the glass fiber reinforced polyamide resin composition being heated at a temperature of 280°C and a shear rate of 91/sec. has a shear viscosity of 400 to 2000 Pa・s,
When extruding a strand from a horizontal flat die installed in a die holder at the tip of a twin-screw extruder, the temperature of the strand from the die hole in the center of the flat die is 310°C to 360°C, and the inside of the die when exiting from the die. A method for producing a glass fiber-reinforced polyamide resin composition, which comprises extruding the strands so that the resin pressure is 2.0 to 8.5 MPa.
2. The manufacturing method according to 1 above, wherein the temperature of the die holder is 250 to 340°C.
3. The manufacturing method according to item 1, wherein the temperature of the strand from the die hole at the end of the flat die is 4 to 14° C. lower than the temperature of the strand from the die hole at the center of the flat die.
4. (A) The manufacturing method according to 1 above, wherein the polyamide resin is composed of one to three of nylon MXD6, nylon 6, and nylon 66.
5. The manufacturing method according to 1 above, wherein the total content of (B) glass fiber and (C) other reinforcing material is 30% by mass or more.
6. (B) The manufacturing method according to 1 above, wherein the glass fibers include glass fibers having a profile ratio in the longitudinal cross-section of 2.0 to 6.0.

According to the production method of the present invention, a glass fiber reinforced polyamide resin composition (pellet) containing a high concentration of glass fibers and other reinforcing materials can be produced by suppressing strand breakage, enabling continuous and stable production, and producing good pellets. It can be manufactured in any shape.

FIG. 2 is a conceptual diagram showing an example of a process from a twin-screw extruder to a pelletizer used in the present invention. It is a figure showing an example of the die section of the twin screw extruder used in the present invention. FIG. 2 is a cross-sectional view showing an example of a horizontal flat die used in the present invention. FIG. 3 is a cross-sectional view showing another example of a horizontally flat die used in the present invention. FIG. 3 is a cross-sectional view showing another example of a horizontally flat die used in the present invention. FIG. 2 is a conceptual diagram of the screw configuration of an extruder used in Examples or Comparative Examples.

Hereinafter, the present invention will be described in detail by showing embodiments, exemplified objects, etc., but the present invention is not limited to the embodiments, illustrative objects, etc. shown below, and may be freely selected without departing from the gist of the present invention. It can be implemented by changing to In this specification, "~" is used to include the numerical values described before and after it as a lower limit value and an upper limit value.

In the production method of the present invention, (A) 20 to 70% by mass of polyamide resin, (B) 10 to 75% by mass of glass fiber, (C) 0 to 40% by mass of other reinforcing materials, and (D) other polymer or A glass fiber-reinforced polyamide resin composition containing 0 to 30% by mass of additives (total of each component is 100% by mass) is produced using a twin-screw extruder.

The extruder used in the present invention is a vent type twin screw extruder, preferably an intermeshing type co-rotating twin screw extruder, which has two screws rotating in the same direction inside the barrel. It is preferable that a kneading section constituted by a plurality of kneading disks is provided in the middle of the screw in a form that meshes with each other.

As shown in FIG. 1, the vented twin-screw extruder has a cylinder equipped with a main raw material hopper 1, an open vent 2, a side feed hopper 3, and a vacuum vent 4, and a die holder 8 at the tip of the cylinder via a flange 6. The screw in the cylinder is driven and rotated by a motor 16 via a screw connection 14 and a gearbox 15.

(A) Polyamide resin and (D) other polymers or additives are supplied from the main raw material hopper 1 and kneaded in the first kneading section (first step). (B) Glass fibers are usually side fed from a side feed hopper 3 located downstream of the first kneading section and kneaded in the second kneading section (second step). (C) Other reinforcing materials may be supplied from the hopper 1, or may be supplied from the side feed hopper 3 like the glass fibers. It may also be supplied from another location.
Next, in the downstream part of the second kneading section, the pressure of the vent 4 is reduced to devolatilize and increase the pressure, and the product is extruded through a die provided in the die holder 8 (third step). The strand 10 coming out of the die is cooled with water and cut with a pelletizer 11 (fourth step) to obtain pellets 12 of the resin composition.

In the first step, (A) the polyamide resin and (D) other polymers or additives are fed into the extruder from the main raw material hopper 1, heated and kneaded with a screw, and melted. A first kneading section configured by a plurality of kneading disks is configured in the middle of the screw. The first kneading section is a kneading section where (A) polyamide resin and (D) other polymers or additives are added and kneaded, and is a kneading section before (B) glass fibers are added. The screw configuration is preferably configured by combining two or more types of R kneading disc, N kneading disc, L kneading disc, L screw, seal ring, mixing screw, or rotor screw, and the length is It is preferable to set it to 4.0 to 9.0D (D is the cylinder diameter). The first kneading section is a kneading section where (A) the polyamide resin and (D) other polymers or additives are added and then kneaded, and is a kneading section before (B) the glass fibers are added.

This first kneading section may be integrated into one, or may be divided into a plurality of parts. That is, the first kneading section may also be divided and a feeding screw may be inserted between them. Even when divided, the total length of the kneading section is preferably within the range of 4.0 to 9.0D.

The R kneading disk (hereinafter sometimes referred to as R) is a progressive kneading disk element, and usually has two or more blades, and preferably has a blade twist angle θ of 10 degrees to 75 degrees. By installing the blades at a predetermined angle, a pseudo-screw structure is formed, and a strong shearing force is applied to the resin while feeding it in the feeding direction, thereby creating a kneading zone.
The L kneading disk (hereinafter sometimes referred to as L) is a reverse kneading disk element, and usually has two or more blades, and the twist angle θ of the blades is -10 degrees to -75 degrees. is preferred. The reverse kneading disk element is an element that has the ability to pressurize the incoming resin and to send the incoming resin back.By installing it downstream of the element that promotes kneading, it increases the pressure of the incoming resin. It dams up the water and exerts a powerful kneading effect.
The N kneading disk (hereinafter sometimes referred to as N) is an orthogonal kneading disk element, and usually has two or more blades, and the twist angle θ of the blades is from 75 degrees to 105 degrees. Since the blades are set at an angle of about 90 degrees, the force for sending out the resin is weak, but the kneading force is strong.

The L screw is a reverse feed screw, the seal ring restricts the flow in the upstream part by each gap in the seal ring part, and the mixing screw is a screw element with the thread (flight part) cut out of the screw, and the rotor A screw is a screw element with one or more threads provided on its outer peripheral surface.

Among these, R kneading discs, N kneading discs, and L kneading discs are preferred, and a configuration in which a plurality of these are combined is preferred.

In the screw configuration of the first kneading section in the first step, it is preferable that an element that promotes kneading is placed on the upstream side, and an element that has a pressure increasing ability is placed on the downstream side. Therefore, in the first kneading section, it is preferable to arrange two or more selected from R, N, and L in the order of R→N→L from the upstream side, and a plurality of each R, N, and L may be arranged. is also preferable. In particular, a configuration in which R is placed upstream, followed by a plurality of Ns, and then L is preferable.

The length of the screw in the first kneading section is preferably in the range of 4.0 to 9.0D, where D is the cylinder diameter. The chemical reaction becomes sufficient, and the occurrence of decomposition of the resin composition can also be suppressed. If the screw length of the first kneading section is shorter than 4.0D, melting and plasticization of the resin tends to be insufficient due to insufficient shearing, and if it exceeds 9.0D, local decomposition of the resin composition progresses due to excessive kneading. This tends to lead to poor mechanical properties of the composition.

After kneading and melting the polyamide resin (A) in the first step, it is preferable to vent through the open vent 2. Preferably, a sealing ring is provided downstream of the open vent 2.

In the second step, after the first step described above, (B) glass fiber is side-fed from the side feed hopper 3 located downstream of the first kneading section, and (A) polyamide is melted with (B) glass fiber. The resin is kneaded in a second kneading section.
The second kneading section means a kneading section into which the (B) glass fibers are introduced, opened and kneaded. The screw configuration of the second kneading section is preferably a combination of one or more of the following: an R kneading disk, an N kneading disk, an L kneading disk, an L screw, a seal ring, and a mixing screw, When kneading with such a screw configuration, the opening and dispersion of the glass fibers (B) tend to be sufficient. Among the above, it is preferable to have at least a mixing screw, particularly a forward feeding notched mixing screw and a reverse feeding notched mixing screw.

The screw length of the second kneading section is preferably in the range of 2.5 to 5.0D. This second kneading section may be integrated into one, or may be divided into a plurality of parts. That is, the second kneading section may be divided into sections and a feeding screw may be inserted between them. In either configuration, the total kneading section length is preferably in the range of 2.5 to 5.0D. By setting the screw length of the second kneading section in this manner, (B) the glass fibers can be opened and dispersed well, and the strength of the resin composition can be easily improved.
(C) Reinforcing materials other than glass fibers may be introduced into the extruder from the same hopper 1 as (A) the polyamide resin, or may be introduced into the extruder from the same place as (B) the glass fibers, as described above. Further, the first kneading section may be divided and the mixture may be added from the middle of the division, or the second kneading section may be divided and the mixture may be introduced from the middle of the division. However, in order to improve the interfacial adhesion with the polyamide resin (A), it is preferable to introduce it from the same place as the polyamide resin (A).

The cylinder set temperature in the second step is generally operated at about 270°C, but in the method of the present invention, it is preferably set at a temperature lower than usual, such as 150 to 250°C. This second kneading section is a step in which (B) glass fiber is introduced and kneaded with (A) polyamide resin and (D) other polymers or additives, and the resin temperature tends to rise. By setting the cylinder temperature in this portion to a temperature range lower than normal, such as 150 to 250° C., it is effective to suppress breakage of the strand 10 when it comes out from the die holder 8. If the temperature is lower than 150°C, the viscosity of the resin tends to increase, and impregnation into (B) glass fibers is not successful, resulting in uneven kneading and the strands tending to break easily. On the other hand, if it is higher than 250°C, the temperature of the resin tends to be high, pyrolysis gas is likely to be generated, and the strands are likely to break. The resin temperature (cylinder temperature) in the second step is more preferably 160°C or higher and 240°C or lower.

The screw rotation speed of the twin-screw extruder is preferably 250 to 800 rpm, more preferably 300 to 700 rpm. In addition, the discharge rate is preferably 200 to 650 kg/h, more preferably 250 to 630 kg/h in the case of "TEX44αIII" manufactured by Japan Steel Works, Ltd., which has an extruder cylinder diameter of 47 mm. For extruders of different sizes, the preferred range is a discharge rate proportional to the 2.5th power of the cylinder diameter ratio.

After the second step, in the third step, the pressure is reduced in the vacuum vent 4 downstream of the second kneading section to devolatilize and increase the pressure, and the product is extruded from a die provided in the die holder 8. The degree of vacuum during vacuum devolatilization in the vacuum vent 4 is preferably -0.097 MPa to -0.07 MPa. Here, the degree of vacuum means gauge pressure.

In the third step, the pressure is increased at the tip of the screw and extruded as a strand from the die. It is necessary that the resin pressure in the die during extrusion is 2.0 to 8.5 MPa.
The resin pressure in the die (also referred to as die pressure) is the resin pressure at the tip of the screw. The pressure at this location is the highest. Usually, a resin pressure gauge 7 is installed at this position, and the pressure can be measured over time. It is necessary that the resin pressure within this die is 2 MPa or more and 8.5 MPa or less. (B) Glass fibers are usually bundled when fed, and by setting the resin pressure in the die to 2.0 MPa or more and 8.5 MPa or less, they are kneaded together with the resin and an appropriate pressure is applied. B) It becomes easier for the resin to be impregnated into the glass fiber bundle, enabling uniform kneading and making it easier to suppress the occurrence of strand breakage. If it is less than 2.0 MPa, non-uniformity will occur in the kneading state of the resin and (B) glass fiber, and the strand will be likely to break when it comes out from the die. (B) Glass fibers are usually bundled when fed, and when they are kneaded together with resin and pressure is applied, (B) resin becomes easier to impregnate into the glass fiber bundles, allowing uniform kneading. Become.
The resin pressure within the die is more preferably 2.5 MPa or more, and even more preferably 3.0 MPa or more. On the other hand, if the resin pressure is too high, the retention area at the tip of the screw becomes long, gas is likely to be generated due to thermal decomposition, and the strand is likely to break due to the gas when it comes out from the die. A more preferable resin pressure is 8.0 MPa or less, and even more preferably 7.0 MPa or less.

The temperature of the die holder 8 is preferably higher than normal, and is preferably 250°C or higher and 340°C or lower. Such a temperature makes it easier to suppress strand breakage. If it is less than 250°C, the temperature of the die will be lower than the resin temperature of the resin composition, and the strand temperature at both ends of the die will be lower than the strand at the center. This causes a difference in viscosity between the strands, making them more likely to break. The temperature of the die holder 8 is more preferably 260°C or higher, particularly 270°C or higher, 280°C or higher, and even more preferably 290°C or higher. When the temperature exceeds 340° C., gas is likely to be generated due to heat retention inside the die, and the strand is also likely to break. The temperature of the die holder 8 is more preferably 335°C or lower, still more preferably 330°C or lower.

A thermocouple 5 and a die holder thermocouple 9 are inserted into the cylinder of the extruder and the die holder 8, so that the temperatures of the cylinder and the die holder can be measured. Furthermore, heaters are built into the cylinder and die holder, making it possible to control the temperature. The temperature of the cylinder and the temperature of the die holder are temperatures measured by an inserted thermocouple.

In a preferred embodiment of the present invention, a horizontal flat die is provided in the die holder 8 at the tip of the twin-screw extruder, and when extruding a strand from this, the temperature of the strand extruded from the central die hole of the horizontal flat die is 310 to 360. It is preferable to set it as °C. Further, in this case, it is preferable that the temperature of the strand extruded from the die hole at the end of the horizontal flat die is 4 to 14° C. lower than the temperature of the strand extruded from the die hole at the center of the flat die.

FIG. 2 is a diagram showing an example of a die section of a twin-screw extruder used in the present invention, and is a cross-sectional view when the die section is cut along a plane parallel to the bottom surface thereof.

The molten polyamide resin composition is fed into the die section from the screw 21 of the twin-screw extruder. The die section includes a breaker plate 23 (or ring plate), a die holder 8, a flange 6, a manifold section 24, and a horizontal flat die 25. In some cases, the die holder is sometimes called a die plate, and the flange is sometimes called a hinge plate. The flange 6 (or hinge plate) and die holder 8 (or die plate) together are generally called a die head.

A screen mesh can be installed inside the breaker plate 23.
The breaker plate 23 is provided with a desired number of holes having a desired diameter d and land length L. Especially when a screen mesh is not used, it is common to install a ring plate 23 which is a ring-shaped plate. In the examples and comparative examples of the present application, a ring plate was installed. This breaker plate and ring plate can prevent resin leakage.

A horizontally flat die is a die having die holes arranged in a horizontal direction. For example, a die having a plurality of die holes 31, 32, 33 arranged in a row horizontally as shown in FIG. It means a die in which holes 31, 32, and 33 are lined up, or a die in which die holes 31, 32, and 33 are lined up horizontally in two rows, upper and lower, as shown in FIG. 4(d). Further, even if the overall shape of the die is round as shown in FIGS. 5(a) and 5(b), a die in which the die holes 31, 32, and 33 from the manifold part 24 are arranged laterally is also included in the horizontally flat die. These are listed as examples of preferred embodiments of the present invention.

When arranged horizontally in two rows, upper and lower, the die holes 32 and 33 at the ends are often arranged below the upper die hole and above the lower die hole, as shown in Fig. 4(d). . This arrangement is obtained when a separating plate 34 is provided between the upper and lower two rows of the horizontal flat die 25 to separate the upper and lower resin flow paths.

In addition, as shown in FIG. 4(e), die holes may be arranged randomly in the horizontal direction. In that case, the die holes 32 and 33 at the left and right ends of the die are the end die holes, and the die hole 31 closest to the geometric center when viewed from the front of the die is the center die hole. The horizontal flat die 25 is generally located at the tip of the manifold part 24 in which the resin flows in the die holder in which the flow path spreads laterally, and is a die having die holes arranged in the horizontal direction. The diameter d of each die hole does not need to be the same, and the land length L of the die hole also does not need to be the same, and the diameter d and land length L may be changed for each die hole.

There are no particular restrictions on the shape of the extrusion die, and known ones can be used. The diameter d of the die hole depends on the desired size of the pellets, but is usually about 2 to 5 mm, preferably about 3 to 4 mm.
The diameter d of each die hole does not need to be the same, and the land length L of the die hole also does not need to be the same, and the diameter d and land length L may be changed for each die hole.

When producing glass fiber-reinforced polyamide resin composition pellets, it is preferable to use this horizontally flat die because it is advantageous in improving productivity. In addition to this, there is also a so-called round die as shown in FIG. 3(c), that is, a die in which die holes are arranged on the circumference, but when aiming at high discharge, the number of die holes increases. As a result, the diameter of the circumference becomes larger, and the strand coming out of the die hole above the circumference has a longer distance to the water tank, making it unstable and making it easier for the strand to break. As described above, in order to improve productivity, a horizontally flat die is preferable because it is advantageous for stable production.
However, in the case of a horizontal flat die, the strands from the end die holes 32, 33 break more easily than the strands from the inner die hole 31. The strands coming out of the die holes 32 and 33 at the ends are easily bent outward when viewed from the center of the die. In a phenomenon called curling, the strands coming out of the die holes 32 and 33 at the ends try to draw a spiral (curling) while turning outward. This curling makes the strand from the die hole at the end easier to break. This becomes more pronounced as the concentration of glass fibers and other reinforcing materials increases.

Although the cause of this curling is not clear, the die holes 32 and 33 at the ends are easily affected by the wall surface of the die holder. It is thought that the frictional force between the resin and the wall of the die holder remains as residual stress, causing the phenomenon of outward bending (curling). In the present invention, the temperature of the strand from the central die hole is 310 to 360°C, and a temperature difference of preferably 4 to 14°C is created between the strand from the center of the die and the strand from the end die, thereby preventing strand breakage at the end. It is preferable to eliminate or minimize the number of strands, and to easily suppress strand breakage of all strands.

The strand temperature at the center of the die is the temperature of the strand immediately after exiting from the die hole 31 closest to the geometric center when the die is viewed from the front. If the number of die holes is odd in the dies arranged at equal intervals in the horizontal direction, it is the average value of the temperature of the die hole in the center of the die, and if the number is even, the temperature of the two strands in the center of the die. This is the temperature immediately after.
The temperature of the strand at the center of the die can be directly measured by contacting it with a thermocouple. Alternatively, the temperature can also be measured using an infrared temperature measuring device. The strand temperature at the center of the die is considered to be close to the resin temperature inside the die.

The temperature of the strand at the end of the die is the temperature of one strand at each of the left and right ends 32 and 33 of the die toward the die. If the temperatures of the left and right strands are different, use the average value. Similarly, it is the strand temperature immediately after exiting the die. The temperature of the strand at the end of the die is easily affected by the temperatures of the die holder, flange, and die. However, since the die holder, flange, and die vary from extruder to extruder, the relationship between their temperature and the strand temperature at the end is not uniformly determined.

The temperature (ΔT) obtained by subtracting the temperature of the strands at both ends of the die from the temperature of the strand at the center of the die is preferably 4° C. or more and 14° C. or less. By setting ΔT in this manner, it is possible to eliminate strand breakage at the ends and further suppress strand breakage of all strands. If ΔT is less than 4° C., the temperature of the strand is high, so the elastic recovery force of the strand at the end decreases, making it easy to break due to curling (elastic recovery force from curling is weak). On the other hand, if ΔT is larger than 14° C., the force itself that causes curling becomes strong, making it easier to break due to curling. In order to adjust ΔT to 4° C. or higher and 14° C. or lower, for example, it is possible to set the temperature of the die holder a little lower than the resin temperature within the die.
Preferably ΔT is 5°C or higher, more preferably 6°C or higher, and preferably 13°C or lower, more preferably 12°C or lower.

The temperature of the strand from the center of the die must be above 310°C and below 360°C. By setting the temperature to such a temperature, the resin component of the resin composition can satisfactorily impregnate the glass fiber bundle, and strand breakage can be eliminated. If it is below 310°C, the viscosity of the resin component of the resin composition is high, impregnation into the glass fiber bundle is poor, bundled fibers remain, and when the strand comes out of the die, stress concentration points are created on the strand and it easily breaks. do.
The temperature of the strand from the center of the die is preferably 315°C or higher, more preferably 320°C or higher. On the other hand, if the temperature exceeds 360° C., the polyamide resin (A) will thermally decompose, gas will be generated, and the strand will easily break due to the gas when it comes out of the die. In addition, when multiple types of polyamide resins are used, amidation exchange reaction progresses and physical properties tend to deteriorate. The temperature of the strand from the center of the die is preferably 355°C or less, more preferably 350°C or less.

Then, in the fourth step, the strand 10 released from the die is cooled with water and cut with a pelletizer 11. The strand temperature when cutting the strand is preferably 100°C or more and 160°C or less. By setting the temperature to such a temperature, it becomes easier to suppress the generation of chips and pellets with defective shapes. If the temperature is less than 100°C, the strands will be hard and chips will easily be generated when cutting with a pelletizer. As a result, plasticization tends to become unstable during molding such as injection molding. If the temperature exceeds 160° C., the oblateness of the cut pellets becomes large, which may also lead to poor plasticization. The strand temperature when cutting the strand is more preferably 110°C or more and 150°C or less.

A glass fiber-reinforced polyamide resin composition containing a high concentration of glass fiber (B) and other reinforcing materials (C) tends to break after exiting the die before being cooled and cut into strands. The resin content is low, the viscoelastic properties are weak, the toughness of the strands is lost, and the strands become brittle and break easily. Furthermore, since the amount of glass fiber is large, fiber bundles with poor opening properties are likely to be generated. A fiber bundle with poor spreadability tends to become a starting point for breakage during strand drawing (stretching). Furthermore, if the fiber bundle is not filled with resin (insufficient resin impregnation into the glass fiber bundle), that portion may become a starting point for breakage. Furthermore, due to the high concentration of glass fibers and other reinforcing materials, the viscosity of the resin increases and the resin temperature tends to rise. This generates pyrolysis gases that cause the strand to break as it exits the die. As described above, it becomes difficult to cut the strand stably due to the decrease in strand toughness, insufficient opening of the glass fiber bundle, insufficient impregnation of resin into the glass fiber bundle, gas generation, etc. When the strand breaks, it is necessary to manually reinsert the strand into the pelletizer. At this time, the flow of the entire strand is disturbed, the strand enters diagonally with respect to the cutter, and long pellets are likely to be generated. Since the glass fiber is highly concentrated and the strands are hard, the cut surface made by the pelletizer is not sharp and becomes dull, resulting in the generation of chips. In order to suppress the generation of chips, it is necessary to increase the strand cutting temperature. This results in sharper cuts and fewer chips. However, if the strand cutting temperature is raised too much, the strand becomes soft and crushed by the take-up roll of the pelletizer, increasing the eccentricity of the elliptical columnar pellet. As the number of these long pellets and chips increases and the oblateness increases, poor plasticization is more likely to occur during injection molding using the pellets, leading to a decrease in productivity. The number of long pellets (usually at least twice the length of the pellet) is preferably less than 3 per 1 kg. The amount of chips is preferably 300 mass ppm or less of the total mass (pellets + chips). Further, the oblateness (major axis/single axis) is preferably 1.30 or less.

The strand 10 is taken off by take-off rollers, brought into contact with water and cooled. For the contact with water, the strand 10 may be cooled by being conveyed through water stored in a cooling water tank 13, or may be cooled by pouring water onto the strand 10 and bringing it into contact with water, or by a mesh belt conveyor. It is also possible to draw a strand and spray water on it with a water spray device. The shorter the time from the time the strand is extruded from the die to the time it cools or enters the water, the better. Normally, it is best to enter the water within 1 second after being extruded from the die.

The cooled strands are sent to a pelletizer by take-up rollers and cut into pellets.

In the method of the present invention, the shear viscosity of the glass fiber reinforced polyamide resin composition at 280° C. and 91/sec is 400 Pa·s or more and 2000 Pa·s or less. By setting the pressure in the range of 400 to 2000 Pa·s and combining it with the above-mentioned processes, strand breakage can be suppressed and continuous stable production can be achieved. If it is less than 400 Pa·s, the elastic properties of the strands will be weak and the strands will easily break. Moreover, when it exceeds 2000 Pa·s, shear heat generation increases, the resin temperature rises, thermal decomposition occurs, and the strands easily break. A more preferable range is 500 Pa·s or more and 1700 Pa·s or less, and an even more preferable range is 600 Pa·s or more and preferably 1400 Pa·s or less.

The shear viscosity is measured at 280° C. and a shear rate of 91/sec in accordance with JIS K7199 using a capillograph (Capillograph, 1D2 manufactured by Toyo Seiki Seisakusho Co., Ltd.) with an orifice having a capillary diameter of 1 mm and a capillary length of 3 mm. It is a value.

The shear viscosity can be adjusted within the above range by changing the viscosity of (A) the polyamide, or by adjusting the amount and molecular weight of (D) other polymers and additives to be blended. But it is possible. It is also possible to change the amount of (B) glass fiber and (C) other reinforcing materials. Furthermore, depending on the thermal history within the extruder, the resin component may undergo thermal decomposition, hydrolysis, or amide exchange reactions, resulting in a decrease in shear viscosity.

Next, the raw material components used in the present invention will be explained.

(A) Polyamide resin (A) Polyamide resin is not particularly limited, and examples thereof include polycaproamide (polyamide 6), polytetramethylene adipamide (polyamide 46), polyhexamethylene adipamide (polyamide 66), and polyamide resin. Undecamethylene adipamide (polyamide 116), polymethaxylylene adipamide (polyamide MXD6), polyparaxylylene adipamide (polyamide PXD6), polyxylylene sebaamide (polyamide XD10), polytetramethylene sebaca polyamide (polyamide 410), polyhexamethylene sebamide (polyamide 610), polydecamethylene adipamide (polyamide 106), polydecamethylene sebaamide (polyamide 1010), polyhexamethylene dodecamide (polyamide 612), decamethylene dodecamide (polyamide 1012), polyhexamethylene isophthalamide (polyamide 6I), polytetramethylene terephthalamide (polyamide 4T), polypentamethylene terephthalamide (polyamide 5T), poly-2-methylpentamethylene terephthalamide (polyamide M-5T), polyhexamethylene terephthalamide (polyamide 6T), polyhexamethylene hexahydroterephthalamide (polyamide 6T (H)), polynonamethylene terephthalamide (polyamide 9T), polydecamethylene terephthalamide (polyamide 10T), Polyundecamethylene terephthalamide (Polyamide 11T), polydodecamethylene terephthalamide (Polyamide 12T), polylauryllactam (Polyamide 12), poly-11-aminoundecanoic acid (Polyamide 11), and copolymers containing these structural units Examples include merging.
(A) Polyamide resin may be used alone or in combination of several types. Among them, (A) polyamide resins include polycaproamide (polyamide 6), polyhexamethylene adipamide (polyamide 66), polymethaxylylene adipamide (polyamide MXD6), and polyhexamethylene terephthalamide (polyamide 6T). Preferable in terms of heat resistance and versatility.

(B) Glass fiber (B) Glass fibers include those normally used in polyamide resin, such as A glass, E glass, alkali-resistant glass composition containing a zirconia component, chopped strand, roving glass, Any known glass fiber can be used regardless of the form of the glass fiber when blending the thermoplastic resin and glass fiber masterbatch. Among them, as the glass fiber (B) used in the present invention, alkali-free glass (E glass) is preferable for the purpose of improving the thermal stability of the resin composition.

(B) The glass fiber may have a round cross section in the longitudinal direction, and it is also preferable to use a glass fiber having a shape ratio of the longitudinal cross section in the range of 2.0 to 6.0.
The irregularity ratio of the longitudinal cross section is defined as a rectangle with the minimum area that circumscribes the cross section perpendicular to the length direction of the glass fiber, the length of the long side of this rectangle is the major axis, and the length of the short side is It is the ratio of the long axis/breadth axis when the short axis is the short axis.
These irregularly shaped glass fibers are difficult to open compared to ordinary glass fibers having a round cross section, and the strands become unstable and easily break due to the unopened glass fibers. Therefore, the range of appropriate extrusion conditions tends to become narrower. In order to promote fiber opening, it is effective to strengthen the kneading conditions or increase the die pressure.

(B) The cross-sectional area of the glass fiber in the longitudinal direction is preferably more than 90 μm ² and 300 μm ² or less. With such a cross-sectional area, the (A) polyamide resin tends to become a matrix, resulting in heat resistance. It is easy to improve gender. The cross-sectional area is more preferably more than 90 μm ² and less than 250 μm ² , and even more preferably more than 90 μm ² and less than 200 μm ² .
(B) The thickness of the glass fiber is not particularly limited, but it is preferable that the short axis is about 2 to 20 μm and the long axis is about 5 to 50 μm.

(B) The glass fibers may be treated with a sizing agent or a surface treatment agent. Furthermore, during the production of the resin composition of the present invention, a sizing agent or a surface treatment agent may be added to the untreated glass fibers for surface treatment.

Examples of the sizing agent include resin emulsions such as vinyl acetate resin, ethylene/vinyl acetate copolymer, acrylic resin, epoxy resin, polyurethane resin, and polyamide resin.
Examples of surface treatment agents include aminosilane compounds such as γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, vinyltrichlorosilane, and methylvinyltrimethoxysilane. Chlorosilane compounds such as chlorosilane, alkoxysilane compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, γ-methacryloxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxy Examples include silane, epoxysilane compounds such as γ-glycidoxypropyltrimethoxysilane, acrylic compounds, isocyanate compounds, titanate compounds, and epoxy compounds.

Two or more of these sizing agents and surface treatment agents may be used in combination, and the amount used (adhered amount) is usually 10% by mass or less, preferably 0.05 to 10% by mass, based on the mass of (B) glass fiber. It is 5% by mass. It is preferable to set the adhesion amount to 10% by mass or less because necessary and sufficient effects can be obtained.

(B) Two or more types of glass fibers may be used in combination depending on the required properties.

(B) The content of glass fiber is 10% by mass of the total of (A) polyamide resin, (B) glass fiber, and (C) reinforcing material other than glass fiber (D) other polymer or additive. The content is as high as ~75% by mass. (B) If the content of glass fiber is less than 10% by mass, the rigidity tends to be insufficient, whereas if it exceeds 75% by mass, the fluidity tends to be insufficient and production tends to be difficult. (B) The content of glass fiber is more preferably 15% by mass or more, still more preferably 20% by mass or more, more preferably 70% by mass or less, and even more preferably 65% by mass or less.

(C) Other reinforcing materials (C) Other reinforcing materials other than glass fibers are reinforcing materials other than glass fibers that have mechanical properties, specifically mechanical properties of molded products obtained by molding pellets. It is a substance that can enhance properties. (C) The shape of the reinforcing material is not particularly limited, and may be, for example, fibrous or granular.
(C) Reinforcing materials other than glass fiber are not particularly limited, and examples include glass flakes, glass beads, powdered glass (milled fiber), acicular wollastonite, mica, talc, unfired clay, whiskers (e.g., titanium Examples include acid potash whiskers), titanium oxide, carbon fibers, ceramic fibers, silica, alumina, kaolin, quartz, graphite, calcium carbonate, barium sulfate, carbon black, and metal powders. Among these, inorganic reinforcing materials such as mica and talc are preferred. (C) Other reinforcing materials may be used alone or in combination.

(C) The amount of other reinforcing materials is 0 to 40% by mass, based on the total 100% by mass of (A) to (D), preferably 35% by mass or less, more preferably 30% by mass or less, and Preferably it is 28% by mass or less.

(D) Other polymers or additives (D) Other polymers or additives are polymers other than (A) polyamide resin and/or various other additives.
(A) Polymers other than polyamide are not particularly limited, and examples include polyphenylene sulfide (PPS), liquid crystal polymer (LCP), aramid resin, polyetheretherketone (PEEK), polyetherketone (PEK), and polyetherimide. (PEI), thermoplastic polyimide, polyamideimide (PAI), polyetherketoneketone (PEKK), polyphenylene ether (PPE), polyethersulfone (PES), polysulfone (PSU), polyarylate (PAR), polyester (PEs) , polycarbonate (PC), polyoxymethylene (POM), polypropylene (PP), polyethylene (PE), polymethylpentene (TPX), polystyrene (PS), polymethyl methacrylate, acrylonitrile-styrene copolymer (AS), Examples include acrylonitrile-butadiene-styrene copolymer (ABS), fluororesin, and polyacrylate. Among these, polyphenylene ether (PPE) and polypropylene (PP) are particularly preferred.
Note that (D) other polymers may be used alone or in any combination and ratio of two or more.

Other additives include flame retardants, flame retardant aids, impact modifiers such as elastomers, stabilizers, mold release agents, colorants such as dyes and pigments, catalyst deactivators, antistatic agents, blowing agents, and plasticizers. agents, crystal nucleating agents, crystallization promoters, etc.

Stabilizers include organic antioxidants such as hindered phenolic antioxidants, sulfur-based antioxidants, and phosphorus-based antioxidants, heat stabilizers, and photostabilizers such as hindered amine-based, benzophenone-based, and imidazole-based antioxidants. Examples include UV absorbers, ultraviolet absorbers, metal deactivators, copper compounds, and alkali metal halide compounds. Among these, copper compounds are preferred. One type of stabilizer may be used alone, or several types may be used in combination. Although the content of the stabilizer can be adjusted as appropriate, it is preferably 5% by mass or less, more preferably 4% by mass or less, and even more preferably 3% by mass or less based on 100% by mass of the resin composition.
Here, the content of the stabilizer is the total content of the stabilizers when the composition contains multiple types of stabilizers.
Copper compounds that can be used as stabilizers include cuprous chloride, cuprous bromide, cuprous iodide, cupric chloride, cupric bromide, cupric iodide, cupric phosphate, Copper salts of organic carboxylic acids such as cupric pyrophosphate, copper sulfide, copper nitrate, and copper acetate can be used. One type of copper compound may be used alone, or several types may be used in combination.

Examples of the mold release agent include long chain fatty acids or their esters, metal salts, amide compounds, polyethylene waxes, silicones, and polyethylene oxides.
The long-chain fatty acid preferably has 12 or more carbon atoms, and includes, for example, stearic acid, 12-hydroxystearic acid, behenic acid, and montanic acid. Partially or completely carboxylic acids may be esterified with mono- or polyglycols or may form metal salts. Examples of amide compounds include ethylene bis-terephthalamide and methylene bis-stearylamide. These mold release agents may be used alone or as a mixture.
The content of the mold release agent is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, preferably 5.0% by mass or less, and 3.0% by mass or less based on 100% by mass of the composition. More preferably, it is 1.0% by mass or less.

(D) The amount of other polymers or additives is 0 to 30% by mass, preferably 25% by mass or less, more preferably 20% by mass or less, based on the total of (A) to (D) 100% by mass. , more preferably 17% by mass or less.

The glass fiber-reinforced polyamide resin composition produced by the method of the present invention can be made into molded products with high strength, so it can fully satisfy the required performance in terms of weight reduction, thinning, and strength, such as in the precision equipment field, automobiles, etc. It can be widely used for molded products or parts in the fields of electrical and electronic equipment, OA equipment such as computers, optical equipment, and various other industrial fields.

Hereinafter, the present invention will be explained in more detail with reference to Examples. However, the present invention is not limited to the following examples, and can be implemented with arbitrary changes within the scope of the gist of the present invention.

The raw material components and their blending ratios (formulations) used in the Examples and Comparative Examples are as listed in Table 1 below.

In the following Examples and Comparative Examples, a vented intermeshing type co-rotating twin screw extruder ("TEX44αIII" manufactured by Japan Steel Works, Ltd., cylinder diameter D = 47 mm) was used as the extruder.

The screw configuration is shown in FIG.
Cylinder position C1 was a feed cylinder, C7 and C12 were vent cylinders, C7 was an open vent, C12 was a vacuum vent, and C9 was a side feed cylinder. The first kneading section for melt-kneading (A) polyester resin and (D) other polymers was arranged from C5 to C6, and the screw configuration was RRNNL with 5 paddles each with 1Ds (1Ds = 44 mm). (B) Glass fibers were side fed from C9. (B) The second kneading section for kneading the glass fibers was equipped with a 1Ds R with five paddles and three 1Ds back mixing screws (lead 0.25Ds) as shown in FIG.

The kneading section where (A) polyamide resin and (D) other polymers and additives are added until (B) glass fiber is fed is the first kneading section, and the period from C1 to C9 is the first step. It is. (C) Other reinforcing materials other than glass fiber were also fed into the same C1 feed cylinder as (A) polyamide resin and (D) other polymers.
Next, (B) the glass fiber enters the extruder and the kneading section up to the vacuum vent is the second kneading section, and the period from C10 to C11 is the second step. The third step includes the C12 to C14 die holder and the process until the kneaded resin composition comes out from the die. Furthermore, the fourth step is to cool the strands coming out of the die with water and cut them with a pelletizer to obtain pellets.

In Examples 1 to 7 and Comparative Examples 1 to 4 below, resin compositions were manufactured using the raw material ratios listed in Formulation 1 in Table 1 above.

Example 1
A twin screw extruder (Japan 100 kg/h of circular cross-section glass fiber (GF1) and 50 kg/h of irregular cross-section glass fiber (GF2) are fed to a side feed hopper. It was then fed to the side feed cylinder of C9. The feed rate of the raw materials was 250 kg/h in total, and the screw rotation speed was 300 rpm.

The set temperature of cylinders C2 to C9 and cylinders C12 to C14 was set to 270°C. The cylinder set temperature of C10 and C11 in the second kneading section was 220°C. The set temperature of the die holder in the third step was 310°C. The temperature of the flange was also 310°C. Further, a horizontal flat die with a die hole diameter of 3.8 mm, a land length of 20 mm, and 10 holes was used. The resin pressure in the die holder at this time was 4.5 MPa. The average temperature of the two strands in the center of the die was 342°C. The average temperature of the strands at both ends of the die was 335°C. In addition, in all Examples and Comparative Examples, the temperature of the flange was set to be the same as the temperature of the die holder.

The take-up speed of the pelletizer was 40 m/min. Extrusion was continued under these conditions for 1 hour. All 10 strands were stable but only broke once. The strands at both ends of the die seemed to curl slightly outward, but did not break.
The strands coming out of the die were cooled in a water tank and cut into strands with a pelletizer to obtain pellets with an average length of 3 mm.

The obtained pellets were dried at 120°C for 5 hours, and the shear viscosity was determined using a capillary diameter of 1 mm and an orifice of 3 mm at a shear rate of 91/sec at a temperature of 280°C using "Capilograph 1D2" manufactured by Toyo Seiki Seisakusho Co., Ltd. I asked for The shear viscosity was 1020 Pa·s.
1 kg of the resulting pellets was visually confirmed, and the number of long pellets (pellets with a length of 6 mm or more) was counted. The results are listed in Table 2.

Strand breakage evaluation was determined based on the following criteria.
◎: Number of strand breaks: 0 times/hour 〇: Number of strand breaks: 1 to 2 times/hour 〇 ^- : Number of strand breaks: 3 to 5 times/hour △: Number of strand breaks: 6 to 9 times/hour ×: Number of strand breaks: 10 times /hour or more The results are shown in Table 2.

Example 2
The same procedure as in Example 1 was performed except that the horizontal flat die had a hole diameter of 3.8 mm and 10 holes, and the land length was changed to 10 mm.

Example 3
The same procedure as in Example 1 was performed except that the horizontal flat die had a hole diameter of 3.8 mm and 10 holes, and the land length was changed to 30 mm.

Example 4
The same procedure as in Example 1 was conducted except that the temperature of the die holder was 285°C.

Example 5
The same procedure as in Example 1 was conducted except that the temperature of the die holder was 330°C.

Example 6
The same procedure as in Example 1 was conducted except that the temperature of the die holder was 260°C.

Example 7
The same procedure as in Example 1 was conducted except that the temperature of the die holder was 345°C.

Comparative example 1
The same procedure as in Example 1 was performed except that the horizontal flat die had a hole diameter of 3.8 mm and 10 holes, and the land length was changed to 5 mm. The resin pressure inside the die was 1.6 MPa. The strands inside the die and at both ends of the die were easily broken, and fibrous fluff was also observed on the strands. It was determined that the resin pressure was low, the impregnation of the resin into the fibers was insufficient, and the opening properties of the fibers were insufficient.

Comparative example 2
The same procedure as in Example 1 was performed except that the horizontal flat die had a hole diameter of 3.8 mm and 10 holes, and the land length was changed to 40 mm. The resin pressure inside the die was as high as 9.1 MPa, and the strands inside the die and at both ends of the die were prone to breakage, and the breakage of the strands was at the outlet of the die, so it was assumed that the strands were broken due to gas.

Comparative example 3
The same procedure as in Example 1 was performed except that the screw rotation was 200 rpm, the horizontal flat die had a hole diameter of 3.8 mm, the number of holes was 10, and the land length was 10 mm. The temperature at the center of the strand die was 306°C. It is believed that the temperature of the resin was low, resulting in insufficient impregnation into the fibers, resulting in poor opening and frequent strand breakage.

Comparative example 4
The same procedure as in Example 1 was conducted except that the screw rotation was 500 rpm. The temperature at the center of the strand die was 363°C. The strand broke in the same way on the inside and on both ends of the die. The strand surface was clean, and no defects in glass fiber opening were observed. Since the strand breakage occurred at the die exit, it was thought that the breakage was caused by gas.

The above results are shown in Table 2 below. In the table, "Actual n" represents Example n, and "Ratio n" represents Comparative Example n.

In Examples 8 to 14 and Comparative Examples 5 to 8 below, resin compositions were manufactured using the raw material ratios listed in Formulation 2 of Table 1 above.

Example 8
Nylon MXD6 (PA1) at 72.5 kg/h, nylon 66 (PA2) at 12.5 kg/h, and nylon 6 (PA3) at 25 kg/h. 37.5 kg/h of mica (C1) and 2.5 kg/h of mold release agent (D2), which are other reinforcing materials, are supplied from the main raw material hopper to the C1 feed barrel of the twin screw extruder "TEX44αIII", and An experiment was conducted in the same manner as in Example 1, except that 50 kg/h of circular cross-section glass fiber (GF1) and 50 kg/h of irregular cross-section glass fiber (GF2) were fed from the side feed hopper to the side feed cylinder of C9.
The strands at both ends seemed to curl slightly outward, but they did not break.
The strands that came out of the die were cooled in a water bath and cut into strands using a pelletizer to obtain pellets. The shear viscosity of the pellets measured in the same manner as in Example 1 was 980 Pa·s.

Example 9
The same procedure as in Example 8 was performed except that the horizontal flat die had a hole diameter of 3.8 mm and 10 holes, and the land length was changed to 10 mm.

Example 10
The same procedure as in Example 8 was performed except that the horizontal flat die had a hole diameter of 3.8 mm and 10 holes, and the land length was changed to 30 mm.

Example 11
The same procedure as in Example 8 was conducted except that the temperature of the die holder was 285°C.

Example 12
The same procedure as in Example 8 was conducted except that the temperature of the die holder was 330°C.

Example 13
The same procedure as in Example 8 was conducted except that the temperature of the die holder was 260°C.

Example 14
The same procedure as in Example 8 was conducted except that the temperature of the die holder was 345°C.

Comparative example 5
The same procedure as in Example 8 was performed except that the horizontal flat die had a hole diameter of 3.8 mm and 10 holes, and the land length was changed to 5 mm. The resin pressure inside the die was 1.5 MPa. The strands inside the die and at both ends of the die were easily broken, and fibrous fluff was also observed on the strands. It was determined that the resin pressure was low, the impregnation of the resin into the fibers was insufficient, and the opening properties of the fibers were insufficient.

Comparative example 6
The same procedure as in Example 8 was performed except that the horizontal flat die had a hole diameter of 3.8 mm and 10 holes, and the land length was changed to 40 mm. The resin pressure inside the die was as high as 8.6 MPa, and the strands inside the die and at both ends of the die were prone to breakage, and since the strand breakage occurred at the outlet of the die, it was assumed that the strand breakage was caused by gas.

Comparative example 7
The same procedure as in Example 8 was performed except that the screw rotation was 200 rpm, the horizontal flat die had a hole diameter of 3.8 mm, the number of holes was 10, and the land length was 10 mm. The temperature at the center of the strand die was 303°C. It is believed that the temperature of the resin was low, resulting in insufficient impregnation into the fibers, resulting in poor opening and frequent strand breakage.

Comparative example 8
The same procedure as in Example 8 was carried out except that the screw rotation was set to 500 rpm. The temperature at the center of the strand die was 362°C. The strand broke in the same way on the inside and on both ends of the die. The strand surface was clean, and no defects in glass fiber opening were observed. Since the strand breakage occurred at the die exit, it was thought that the breakage was caused by gas.

The above results are shown in Table 3 below.

In Examples 15 to 21 and Comparative Examples 9 to 12 below, resin compositions were produced using the raw material ratios listed in Formulation 3 of Table 1 above.

Example 15
12.5 kg/h of nylon MXD6 (PA1), 7.5 kg/h of nylon 66 (PA2), 57.5 kg/h of nylon 6 (PA3), and 62.5 kg/h of mica (C1), which is another reinforcing material. 5 kg/h, mold release agent (D2) 2.5 kg/h was supplied from the main raw material hopper to the C1 feed barrel of the twin screw extruder "TEX44αIII", and further, circular cross-section glass fiber (GF1) 20 kg/h, irregular cross-section An experiment was carried out in the same manner as in Example 1, except that 50 kg/h of glass fiber (GF2) was supplied from the side feed hopper to the side feed cylinder of C9.
The strands at both ends seemed to curl slightly outward, but they did not break at either end. The inner strand only broke twice.
The strands that came out of the die were cooled in a water bath and cut into strands using a pelletizer to obtain pellets. The shear viscosity of the pellet measured in the same manner as in Example 1 was 1050 Pa*sec.

Example 16
The same procedure as in Example 15 was performed except that the horizontal flat die had a hole diameter of 3.8 mm and 10 holes, and the land length was changed to 10 mm.

Example 17
The same procedure as in Example 15 was performed except that the horizontal flat die had a hole diameter of 3.8 mm and 10 holes, and the land length was changed to 30 mm.

Example 18
The same procedure as in Example 15 was conducted except that the temperature of the die holder was 285°C.

Example 19
The same procedure as in Example 15 was conducted except that the temperature of the die holder was 330°C.

Example 20
The same procedure as in Example 15 was conducted except that the temperature of the die holder was 260°C.

Example 21
The same procedure as in Example 15 was conducted except that the temperature of the die holder was 345°C.

Comparative example 9
The same procedure as in Example 15 was performed except that the horizontal flat die had a hole diameter of 3.8 mm and 10 holes, and the land length was changed to 5 mm. The resin pressure inside the die was 1.8 MPa. The strands inside the die and at both ends of the die were easily broken, and fibrous fluff was also observed on the strands. It was determined that the resin pressure was low, the impregnation of the resin into the fibers was insufficient, and the opening properties of the fibers were insufficient.

Comparative example 10
The same procedure as in Example 15 was performed except that the horizontal flat die had a hole diameter of 3.8 mm and 10 holes, and the land length was changed to 40 mm. The resin pressure inside the die was as high as 9.6 MPa, and the strands inside the die and at both ends of the die were prone to breakage, and the breakage of the strands was at the outlet of the die, so it was assumed that the strands were broken due to gas.

Comparative example 11
The same procedure as in Example 15 was performed except that the screw rotation was 200 rpm, the horizontal flat die had a hole diameter of 3.8 mm, the number of holes was 10, and the land length was 10 mm. The temperature at the center of the strand die was 308°C. It is believed that the temperature of the resin was low, resulting in insufficient impregnation into the fibers, resulting in poor opening and frequent strand breakage.

Comparative example 12
The same procedure as in Example 15 was carried out except that the screw rotation was set to 500 rpm. The temperature at the center of the strand die was 367°C. The strand broke in the same way on the inside and on both ends of the die. The strand surface was clean, and no defects in glass fiber opening were observed. Since the strand breakage occurred at the die exit, it was thought that the breakage was caused by gas.

The above results are shown in Table 4 below.

According to the production method of the present invention, it is possible to stably produce high-quality pellets of a glass fiber-reinforced polyamide resin composition containing a high concentration of glass fibers.

1: Main raw material hopper 3: Side feed hopper 4: Decompression vent 5: Second kneading section thermocouple 6: Flange 7: Resin pressure gauge 8: Die holder 9: Die holder thermocouple 10: Strand 11: Pelletizer 12: Pellet 13: Cooling water tank 15: Gearbox 16: Motor 20: Cylinder tip 21: Screw 23: Ring plate 24: Manifold section 25: Horizontal flat die 31, 32, 33: Die hole

Claims (6)

(A) 20-70% by weight of polyamide resin, (B) 10-75% by weight of glass fiber, (C) 0-40% by weight of other reinforcing materials, and (D) 0-30% by weight of other polymers or additives. (The total of each component is 100% by mass) A method for producing a glass fiber reinforced polyamide resin composition using a twin screw extruder, the glass fiber reinforced polyamide resin composition being heated at a temperature of 280°C and a shear rate of 91/sec. has a shear viscosity of 400 to 2000 Pa・s,
When extruding a strand from a horizontal flat die installed in a die holder at the tip of a twin-screw extruder, the temperature of the strand from the die hole in the center of the flat die is 310°C to 360°C, and the inside of the die when exiting from the die. A method for producing a glass fiber-reinforced polyamide resin composition, which comprises extruding the strands so that the resin pressure is 2.0 to 8.5 MPa. The manufacturing method according to claim 1, wherein the temperature of the die holder is 250 to 340°C. The manufacturing method according to claim 1, wherein the temperature of the strand from the die hole at the end of the flat die is 4 to 14° C. lower than the temperature of the strand from the die hole at the center of the flat die. The manufacturing method according to claim 1, wherein the polyamide resin (A) comprises one to three of nylon MXD6, nylon 6, and nylon 66. The manufacturing method according to claim 1, wherein the total content of (B) glass fiber and (C) other reinforcing material is 30% by mass or more. 2. The manufacturing method according to claim 1, wherein the glass fiber (B) includes a glass fiber having a profile ratio in the longitudinal cross section of 2.0 to 6.0.

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