JP2001277278A - Molding method and molded article of glass fiber reinforced thermoplastic resin molded article - Google Patents

Abstract

(57) [Summary] [Problem] To provide high strength, excellent surface appearance,
Provided is a molding method capable of obtaining a glass fiber reinforced thermoplastic resin molded product which is free from deformation and the like and is lightweight. SOLUTION: A thermoplastic resin containing glass fibers is plasticized by a plasticizing / injection device (KS), and a foamed molten injection material in which a carbon dioxide fluid in a supercritical state is dissolved is obtained. This is injected into the cavities (C′1, C′2) of the dies (31, 35) that are under counter pressure by carbon dioxide gas, and then the cavities (C′1, C′2) are obtained. Expanded to a volume corresponding to the molded article to be foamed. Alternatively, it is injected and filled, and then expanded and foamed to a volume corresponding to the molded product whose cavity is to be obtained. Alternatively, the injected foamed molten injection material is compressed, and then expanded to a volume corresponding to the molded product whose cavity is to be obtained, and foamed. When expanding, the counter pressure is released at a stretch.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for plasticizing an injection material made of a thermoplastic resin containing a predetermined amount of glass fiber with a plasticizing / injection device, and for molding a plasticized foamed molten injection material into a mold. The present invention relates to a molding method of a glass fiber reinforced thermoplastic resin molded article, which is obtained by injecting or filling a cavity into a glass fiber reinforced thermoplastic resin, and a molded article obtained by performing this method.

[0002]

2. Description of the Related Art Glass fiber reinforced thermoplastic resin molded products are:
Because of its excellent mechanical properties such as tensile strength, rigidity and heat resistance, it is widely used as automobile parts such as instrument panels and bumper beams or as exterior engineering panels such as exterior wall panels and cables and troughs. Such a glass fiber reinforced thermoplastic resin molded product is generally molded by an injection molding machine. The injection molding machine generally includes a plasticizing / injection device and a mold device, as is well known in the art. Plasticizing / injection equipment consists of a screw cylinder and
A screw is provided in the screw cylinder so as to be drivable in the rotational direction and the axial direction. On the other hand, the mold apparatus includes a fixed mold, a movable mold that is opened and closed with respect to the fixed mold, a mold clamping device, and the like. A cavity is formed on the parting line side of the fixed mold and the movable mold to give a shape to the molded product. Therefore, the injection material containing glass fiber is plasticized and measured by the plasticizing / injection device, injected into the cavity formed by clamping, and the movable mold is opened after cooling and solidification. A thermoplastic resin molded product is obtained.

As described above, a glass fiber reinforced thermoplastic resin molded article can be obtained by an injection molding machine, and the improved injection molding method is disclosed in Japanese Patent Application Laid-Open No. H10-305467.
No. In the injection molding machine used for carrying out this injection molding method, the diameter of the screw cylinder, the groove depth of the screw, the diameter of the injection nozzle, and the like are improved. Further, the length, arrangement state, content and the like of glass fibers contained in the thermoplastic resin are also limited. The above publication discloses a molding method for obtaining a glass fiber reinforced thermoplastic resin molded article using the improved injection molding machine and the injection material as follows. That is, the injection material containing glass fibers is plasticized and measured. On the other hand, the movable mold is clamped to the fixed mold to form a cavity. At this time, the mold is clamped so that the volume or thickness of the cavity is smaller than the thickness of the molded product to be obtained. Then, the plasticized melt injection material is injected. Before the injected molten injection material is solidified, it is spread to the thickness of the molded product for which a movable mold is to be obtained. Then, the molten resin expands to the full extent of the cavity due to the spring action of the contained glass fiber to restore the original state. At this time, many cavities or cells are formed inside the molded product.

[0004]

As described above, a molded article of glass fiber reinforced thermoplastic resin can be obtained, but if the glass fiber is broken during molding, a molded article having a desired tensile strength cannot be obtained. Will be. Further, since glass fibers having a large specific gravity are contained, the weight of the molded article increases. By the way, the injection molding machine disclosed in Japanese Patent Application Laid-Open No. 10-305467 has improved the diameter of the screw cylinder, the groove depth of the screw, the diameter of the injection nozzle, etc., so that the breakage of the glass fiber is avoided to some extent. Also, a number of cavities are formed inside, the apparent specific gravity is reduced, and the weight is reduced. However, there is room for improvement. For example, the injected melt-injected material becomes full of cavities due to springback of glass fibers, but the springback force is weak, so that the transferability of the surface of the molded product may not be sufficient. Further, although a number of cavities are formed, the size of the cavities becomes non-uniform due to the springback force of the glass fiber, and the strength of the molded product may be reduced. Further, if the molded product has a thin portion and a thick portion, a cavity is formed in the thin portion, but since the springback force of the glass fiber is weak, it is difficult to form a sufficient cavity in the thick portion. . As described above, if there are cavities in the inside of the molded article, the strength of the molded article is increased or decreased, and the molded article is warped or deformed.

However, the above publication also discloses a molding method in which an azo compound such as azodicarbonamide and a chemical blowing agent such as a nitro compound are mixed. According to this molding method, the springback force of the glass fiber is assisted, and a large number of uniform foam cells are formed. However, since the flow resistance of the molten resin mixed with the chemical blowing agent is generally large, it is difficult to fill the narrow cavity. In order to fill even a narrow cavity, the injection pressure must be increased, but if it is increased, the chance of breaking the glass fiber increases. Further, the chemical foaming agent is expensive, and causes an increase in the cost of a molded product. Further, the decomposition residue of the chemical foaming agent remaining in the molded article may cause discoloration of the molded article or may cause odor. In addition, there is a risk of generating harmful substances such as dioxin. For these reasons, the use of chemical blowing agents is not always preferred. An object of the present invention is to provide a molding method of a glass fiber reinforced thermoplastic resin molded article which solves the above-mentioned problems, and specifically has a large strength, an excellent surface appearance, warpage, deformation and the like. It is an object of the present invention to provide a molding method of a glass fiber reinforced thermoplastic resin molded article which is free and lightweight, and a molded article obtained by performing the molding method.

[0006]

SUMMARY OF THE INVENTION According to the present invention, when a physical blowing agent such as carbon dioxide gas or nitrogen gas is dissolved in a glass fiber reinforced thermoplastic resin, the flow resistance or viscosity of the molten resin is reduced, and Have been made based on the finding that they have become finer and have a higher foaming power. That is, in order to achieve the above object, the present invention plasticizes an injection material made of a thermoplastic resin containing a predetermined amount of glass fiber with a plasticization / injection device, and also uses a physical material such as carbon dioxide gas and nitrogen gas. It is configured to obtain a foamed melt-injected material into which a typical foaming agent has been injected and dissolved, and to foam it while injecting and filling it into a mold cavity. The invention according to claim 2 is characterized in that an injection material made of a thermoplastic resin containing a predetermined amount of glass fiber is plasticized by a plasticizing / injection device, and a physical blowing agent such as carbon dioxide gas and nitrogen gas is used. The injected and melted foamed molten injection material was obtained, and injected into a mold cavity under counter pressure with an inert gas such as nitrogen gas, carbon dioxide gas, or argon gas, and then the cavity was obtained. According to the third aspect of the present invention, an injection material made of a thermoplastic resin containing a predetermined amount of glass fiber is plasticized and injected. While plasticizing with the device, a foamed molten injection material in which a physical foaming agent such as carbon dioxide gas and nitrogen gas was injected and dissolved was obtained, and this was used as nitrogen gas, carbon dioxide gas, and argon gas. 5. A method of injecting and filling a cavity of a mold which has been subjected to counter pressure with an inert gas, and expanding and expanding the cavity to a volume corresponding to a molded product for which the cavity is to be obtained. The invention described in (1) plasticizes an injection material made of a thermoplastic resin containing a predetermined amount of glass fiber with a plasticizing / injection device, and injects and dissolves a physical blowing agent such as carbon dioxide gas and nitrogen gas. Obtained foam melt injection material, and inject it into a mold cavity under counter pressure with an inert gas such as nitrogen gas, carbon dioxide gas, argon gas, etc., and inject the injected foam melt injection material. Compressing and then expanding to a volume corresponding to the molded article for which the cavity is to be obtained, and foaming, and the invention according to claim 5, The molding method according to any one of claims 2 to 4, wherein when the foam is expanded to a volume corresponding to the molded article whose cavity is to be obtained and foamed, the counter pressure is released in connection with the expansion. Is done. The invention according to claim 6 is configured to be a glass fiber reinforced thermoplastic resin molded product obtained by the molding method according to any one of claims 1 to 5.

[0007]

Embodiments of the present invention will be described below. As shown in FIG. 1, an injection molding apparatus used for carrying out a method for molding a glass fiber reinforced thermoplastic resin molded product according to an embodiment of the present invention is generally a plasticizing / injecting apparatus KS. And a mold apparatus KA. The plasticizing / injection device KS is disclosed in Japanese Patent Application No. Hei 11
171892, 11-300412, 11-
Although it can be configured as described in 337718 or the like, in the embodiment shown in FIG. 1, as proposed in Japanese Patent Application No. 11-300473,
The screw cylinder 1 includes a screw 20 that is driven to rotate in the plasticizing direction in the screw cylinder 1 and is also driven in the axial direction, that is, the injection direction, and an inert gas supply device 10.

The screw cylinder 1 has a predetermined length in the axial direction, and supplies an inert gas having a pressure equal to or higher than the supercritical gas pressure reaching the inside of the screw cylinder 1 from the outside at a substantially intermediate position. The gas supply hole 2 is opened. The inert gas supply device 1 is inserted into the gas supply hole 2.
The gas pipe 3 connected to 0 is airtightly connected.
In the present embodiment, the inert gas supply device 10 includes an inert gas cylinder 11 filled with a carbon dioxide gas, a nitrogen gas, or the like, and the inert gas supplied from the supercritical gas pressure of several MPa to 20 MPa.
The compressor includes a compressor 12 for increasing the pressure to about MPa, throttle valves 13 and 13 provided in the gas pipe 3, and electromagnetic switching valves 14 and 14. Note that the inert gas supply device 10 does not have a special heating device for heating the inert gas to a supercritical temperature or higher. However, when the inert gas is supplied into the screw cylinder 1, the inert gas is supplied by a molten resin material. It is heated above the supercritical temperature and becomes liquid. As described above, a heating device is not necessary, but preheating can be performed using waste heat generated from an injection molding device or the like in order to avoid a decrease in temperature of the resin material in a molten state.

The screw cylinder 1 has a measuring chamber 4 near the left end in FIG. 1, and an injection nozzle 5 is provided at the front end thereof. The injection nozzle 5 is provided with a shut-off valve 6 having a conventionally known structure. A material supply hole is formed near the rear end of the screw cylinder 1 and a screw driving device is provided at the rear end, but these are not shown in FIG. The screw driving device can be configured in a conventionally known manner, and therefore will not be described in detail. For example, the screw driving device includes a rotary motor and a piston / cylinder unit, and has an output shaft of the rotary motor and
The screw shaft at the rear end is connected by mechanical means such as a spline shaft and a sliding key. Therefore, even when the screw 20 is driven to rotate, it can be moved in the axial direction. The piston of the piston / cylinder unit can apply a supercritical pressure to the molten resin at the time of measurement, and can also inject the measured foamed molten injection material. A plurality of heaters whose temperatures are individually controlled are provided on the outer peripheral portions of the screw cylinder 1 and the injection nozzle 5, and the temperature inside the screw cylinder 1 is maintained at a supercritical temperature or more, for example, 100 degrees Celsius or more. However, the heater is not shown in FIG.

An injection material made of a glass fiber reinforced thermoplastic resin material is supplied to a material supply hole. Screw 20
Moves in the axial direction during plasticization and injection,
Although not always accurate, as shown in FIG.
Corresponding to the screw cylinder 1, the rear end is the first stage S1, and the front end is the second stage S2. The first stage S1 includes a supply unit K and a first stage ahead of the supply unit K.
It comprises a compression section A1 and a first metering section M1 on the other side. The supply section K corresponds to a material supply hole of the screw cylinder 1, and the screw groove 21 is relatively deep. The screw groove 21 of the first compression part A1 temporarily changes from the groove depth of the supply part K to the screw groove depth of the first metering M1. Screw groove 2 of first metering part M1
1 is shallow. The injection material made of the glass fiber reinforced thermoplastic resin material sent from the supply unit K by the rotation of the screw 20 receives heat from the heater provided in the screw cylinder 1 and is compressed by the first compression unit A1. The first metering portion M melts while undergoing a shearing action.
In No. 1, it is completely melted. This prevents the injected inert gas from leaking toward the supply section K.
That is, it is sealed by the molten resin.

The second stage S2 comprises a decompression section G following the first stage S1, a second compression section A2 ahead of it, and a second metering section M2 ahead of it. The screw groove 21 of the decompression section G is deep. Thus, the pressure of the molten resin sent from the first stage S1 is reduced. Further, the pressure reducing section G is selected to have a length that can cover the gas supply hole 2 even when the screw 20 moves in the axial direction. The screw groove 21 of the second compression part A2 is relatively shallow, and the screw groove 21 of the second metering part M2 is further shallow, and is filled with molten resin. Thereby, the injected inert gas is sealed by the molten resin of the second metering portion M2.

Screw groove 21 of pressure reducing section G of screw 20
Is deeper and the volume between the flights 23 and 23 is increased, but instead of making the screw groove 21 deeper, the width between the flights 23 and 23 can be increased by reducing the width of the flight 23. Further, the pitch of the flights 23 can be increased, and the volume between the flights 23 can be increased. Further, it is clear that the screw groove 21 can be deepened, the width of the flight 23 can be narrowed, and the pitch can be widened.

The mold apparatus KA includes a fixed platen 30, a fixed die 31 attached to the fixed platen 30, a fixed die 31
A movable mold 35 is opened and closed with respect to the movable mold 35, a counter pressure adding device 40, and the like. A movable plate to which the movable mold 35 is attached, a mold clamping device for clamping the movable mold 35 to the fixed mold 31 or opening the mold at a predetermined speed, an ejector device for ejecting a molded product, and the like are not shown. The fixed mold 31 has a recess 32 having a predetermined size and a predetermined depth, which is open toward the parting line P. The sprue 33 through which the foamed molten injection material passes at the time of injection is opened at the bottom of the concave portion 32.
On the parting line P side of the movable mold 35, first and second cores 36 and 37 having a predetermined height and a predetermined size corresponding to the concave portions 32 of the fixed mold 30 are provided. The first and second cores 36 and 37 allow the recess 3 of the fixed mold 31 to be formed.
In cooperation with 2, a cavity C1 for molding the bottom of the molded article and a cavity C2 for molding a peripheral wall rising by a predetermined amount connected to the bottom wall are formed. Second
The core 37 is formed around the first core 36 so as to be lower and larger than the core 36. This second
The peripheral wall of the core 37 slides in close contact with the inner peripheral wall of the concave portion 32 of the fixed mold 31.

Cavity C1 configured as described above,
A counter pressure adding device 40 for applying a counter pressure to C2 includes a gas cylinder 41 filled with an inert gas such as carbon dioxide gas and nitrogen gas, a pressurizer for pressurizing the inert gas to a supercritical pressure or higher, and a pressure control valve 4.
2. Electromagnetic on-off valves 43, 43, etc., and the terminal end of the pipeline 44 connecting these valves is open to the cavity C2.

The injection molding apparatus according to the present embodiment also includes a controller including a controller, a timer, and the like, but is not shown in FIG. The controller is provided with a setting device. A timer for setting various values required for plasticization, injection, mold opening speed, and the like, for example, upper and lower limits of the pressure of the inert gas, the start time of the supply of the inert gas, and the stop time by the setting device. The setting, the rotation speed of the rotation motor of the screw driving device, the back pressure value at the time of plasticization, the temperature of the heater provided on the outer periphery of the screw cylinder 1 and the injection nozzle 5, the addition and opening timing of the counter pressure, etc. are set. I can do it.
Then, so that the above various values are maintained at the set values,
For example, feedback control is performed by the controller. Also,
When the pressure of the inert gas exceeds the upper and lower limits, an alarm or the like is activated, and the plasticizing / injection device KS is stopped. Such a controller, a pressure gauge P1 provided in the gas pipe 3, and a screw cylinder 1
Pressure gauge P2 provided in the second metering portion M2 of
The pressure gauge P3, the screw driving device, the feeder driving device, and the like provided in the measuring chamber 4 are connected by signal lines.

Next, an example of molding using the above-described injection molding apparatus will be described. Injection materials include, for example,
As described in Japanese Patent No. 305467, the total length of the pellets is 5 to 100 mm, and reinforcing glass fibers of the same length are arranged in parallel with each other and contain 20 to 80% by weight of the whole. It is desirable to use a drip. If the length of the glass fiber is less than 5 mm, the strength, rigidity, etc. of the molded product may be insufficient, and if it exceeds 100 mm, it may cause poor plasticization or cause a blitch at the time of injection. Further, if the weight of the glass fiber is less than 20%, the rigidity and impact resistance of the molded product are insufficient, and if it exceeds 80%, the glass fiber is exposed on the surface of the molded product, which may impair the appearance quality. .

The injection material made of the above-mentioned glass fiber reinforced thermoplastic resin material is put into a hopper. Various values necessary for plasticization, for example, upper and lower limits of the pressure of the inert gas in the gas pipe 3, the pressure value of the second metering section M2, and the pressure in the measuring chamber 4 are set by the setting device attached to the controller. The value, the temperature of the heater, the metering completion position of the screw 20, the rotation speed of the screw 20, the mold clamping interval of the movable mold 35, the mold opening speed, and the like are set. Further, the shut-off valve 6 is closed.
The injection material is supplied to the screw cylinder 1 at a set ratio. The screw 20 is driven to rotate by the screw driving device to start the measuring process. The injection material is screw 2
0 is supplied to the supply unit K. The injection material sent by the rotation of the screw 20 includes heat added from a heater,
Melting occurs due to heat generated by a frictional action, a shearing action, and the like due to rotation of the screw 20, and the first through the first compression portion A1
It is sent to the metering unit M1. First metering unit M1
And is sent to the next second stage S2. At this time, the temperature inside the screw cylinder 1 is
The temperature is higher than the supercritical temperature of the inert gas, for example, 100 degrees Celsius or higher.

When the timer of the controller has timed out, an inert gas such as carbon dioxide gas or nitrogen gas is injected from the inert gas supply device 10 into the pressure reducing section G of the second stage S2. Molten resin completely melted in the first metering portion M1 forms an inner peripheral wall of the screw cylinder 1,
The space between the flights 23, 23 and the outer peripheral surface 21 of the screw shaft is filled, and the molten resin of the first metering portion M1 prevents the injected inert gas from leaking toward the supply portion K. . When the molten resin is injected, the screw groove 21 of the decompression section G is deepened, and the pressure of the molten resin is low.
The injection can be performed at a relatively low pressure of about 0 MPa. The injected inert gas becomes a fluid, and the screw 2
With the rotation of 0, it easily penetrates and dissolves in the molten resin. As a result, the injection material becomes a foamed melt injection material. Then, it is sent to the second metering unit M2 via the second compression unit A2 of the second stage S2. Also at this time, the second compression unit A
An inert gas is supplied so that the pressure of the second and second metering portions M2 does not become lower than the supercritical pressure. The inert gas injected by the molten resin in the second metering portion M2 is prevented from leaking to the front of the screw cylinder 1.

The foamed molten injection material in which the inert gas is dissolved as a fluid is sent to the measuring chamber 4. As the measurement proceeds, the screw 20 retreats rearward due to the measured pressure of the foamed molten injection material. At this time, the pressure in the measuring chamber 4 is measured by the pressure gauge S3, and the screw 20 is pressurized in the injection direction and measured so that the measured pressure does not become lower than the supercritical pressure. When the predetermined amount is retracted, this is detected and the weighing is completed. Next, the injection step is started. In the injection step, the injection of the inert gas is continued. The timer times out and stops the infusion. Before the injection step, the screw 20 is moved in the injection direction and pressurized so that the measured pressure of the foamed molten injection material does not drop below the supercritical pressure. Alternatively, it can be rotationally driven at a low speed in the plasticizing direction.

FIG. 2A is a view showing a molding process according to the first embodiment of the present invention, and FIG.
As shown in FIG. 5, the distance between the parting lines P, P of the fixed mold 31 and the movable mold 35 is T1.
The movable mold 35 is clamped. The cavities C′1 and C′2 formed by the interval T1 are thinner or smaller in volume by a predetermined amount than the cavities C1 and C2 of the molded product to be obtained. In addition, counter pressure adding device 4
A counter pressure of a predetermined pressure is applied to the cavities C′1 and C′2 from 0. Next, the shutoff valve 6 is opened, and the screw 20 is driven in the axial direction to inject the screws into the cavities C′1 and C′2. A state in which the space SP remains in the cavities C′1 and C′2 after the injection is completed is shown in FIG. Before the injected foamed injection material is solidified, the movable mold 35 is opened at a predetermined speed so that the interval between the parting lines P, P is T2. By opening at the interval T2, the cavities C1 and C2 of the molded product to be obtained have the size. By opening,
Alternatively, by expanding the cavities C′1 and C′2, the pressure in the cavities C1 and C2 decreases, and foaming starts. In connection with this mold opening, the counter pressure is released at a stretch. The foam melt injection material assists the spring back action of the glass fiber, and the cavities C1, C
2 Fully foam and expand. The expanded state is shown in FIG.
(B). Movable mold 3 after cooling and solidification
5, the movable mold 35 is opened due to the difference in the surface area of the molded product.
(The average cell diameter is 0.01 to 50 μm,
A substantially box-shaped glass fiber reinforced thermoplastic resin molded article having an average cell density of 10 ⁸ to 10 ¹⁶ cells / cm ³ is projected. Hereinafter, molding is performed in the same manner.

According to the first embodiment, since the foamed molten injection material is filled in the cavities C′1 and C′2 so that the space SP remains, the injection pressure may be low. As a result, the glass fibers are less likely to be damaged. Further, since the inert fluid is dissolved in the foamed molten injection material, the springback force of the glass fiber is compensated for, and the thick portion formed by the cavity C2 foams uniformly and finely. Therefore, a molded article having high strength and little warpage and deformation can be obtained. Further, the surface transferability is also improved.
Further, since an inert fluid is dissolved in the foamed molten injection material, the flow resistance is small and the cavities C1, C2
, And evenly penetrates and expands into every corner, and a molded product with high shape quality can be obtained. Further, since an inert fluid is used as the foaming agent, the molded article does not discolor and does not pollute the environment.

Next, FIG. 2B shows the second embodiment of the present invention.
An embodiment will be described. In the same manner as in the first embodiment, a foam melt injection material in which a physical foaming agent is dissolved is obtained. The movable mold 35 is clamped so that the interval between the parting lines P, P between the fixed mold 31 and the movable mold 35 becomes T1. The cavities C'1 constituted by this interval T1,
C′2 is the cavities C1, C2 of the molded article to be obtained.
Thinner by a predetermined amount or smaller in volume. Also,
A counter pressure of a predetermined pressure is applied to the cavities C ′ 1 and C ′ 2 from the counter pressure adding device 40. Next, the shut-off valve 6 is opened, and the screw 20 is driven in the axial direction to inject and fill the cavities C′1 and C′2 fully. Figure 2 shows the state after injection and filling are completed.
(B) and (a) of FIG. Before the injected foamed molten injection material is solidified, the movable mold 35 is opened at a predetermined speed so that the interval between the parting lines P, P is T2. By opening at the interval T2, the cavities C1 and C2 of the molded product to be obtained have the size. By opening, the pressure in the cavities C1, C2 decreases, and foaming starts. In connection with this mold opening, the counter pressure is released at a stretch. The foam melt injection material is Cavity C
1, foam and expand to full C2. The expanded state is shown in (b) of FIG. When the movable mold 35 is opened after cooling and solidification, the glass fiber reinforced thermoplastic resin molded product is protruded as described above. Hereinafter, molding is performed in the same manner.

According to the second embodiment, the same effect as that of the first embodiment can be obtained. However, according to the present embodiment, the foamed molten injection material is completely filled with the cavities C′1 and C′2. Therefore, the surface transferability is improved. In addition, the foamed molten injection material is filled to fill the cavities C'1 and C'2, but since the inert fluid is dissolved in the foamed molten injection material, the flow resistance is small, and even if the injection pressure is low, the material is filled. Yes, without damaging the glass fibers.

In the first and second embodiments, the cavities are subjected to the counter pressure. However, the cavities which are not subjected to the counter pressure may be filled. At this time, the foamed melt-injected material is foamed while being filled, but since the foamed melt-injected material in which a body-physical foaming agent such as an inert fluid is dissolved has a low viscosity and a low flow resistance, The cavity is filled to every corner, and molding defects such as short shots do not occur. In addition, foaming can be performed while opening the movable mold in accordance with the filling speed of the foamed molten injection material without applying counter pressure.

Finally, a third embodiment of the present invention will be described with reference to FIG. In the same manner as in the first embodiment, a foam melt injection material in which a physical foaming agent is dissolved is obtained. The movable mold 35 is clamped so that the interval between the parting lines P, P of the fixed mold 31 and the movable mold 35 is a predetermined interval T′1. Cavity C 'composed of this interval T'1
1, C'2 is the cavity C1, of the molded product to be obtained,
It is narrower by a predetermined amount than C2. Further, counter pressure of a predetermined pressure is applied to the cavities C ′ 1 and C ′ 2 from the counter pressure adding device 40. Next, the shut-off valve 6 is opened, and the screw 20 is driven in the axial direction to eject the cavity C'1 and C'2 in a state where some space SP remains. The state after the injection is completed is shown in FIG.
Is shown in Subsequently, the movable mold 35 is clamped with a predetermined clamping force before the foamed molten injection material is solidified. That is, the injected foamed molten injection material is compressed. FIG. 3B shows a state in which the cavities are compressed to have the thickness C. Next, the movable mold 35 is opened at a predetermined speed so that the interval between the parting lines P, P is T2. By opening at the interval T2, the cavities C1 and C2 of the molded product to be obtained have the size.
By opening, the pressure in the cavities C1, C2 decreases, and foaming starts. In connection with this mold opening, the counter pressure is released at a stretch. The foamed molten injection material foams and expands to fill the cavities C1 and C2 as described above. The expanded state is shown in FIG.
When the movable mold 35 is opened after cooling and solidification, a glass fiber reinforced thermoplastic resin molded product is obtained. Hereinafter, molding is performed in the same manner.

According to the third embodiment, the same effects as those of the first and second embodiments can be obtained. However, according to the present embodiment, before the foamed melt-injected material is foamed and expanded, Due to the compression, the effect of further improving the surface transferability can be obtained.

[0027]

As described above, according to the present invention, an injection material made of a thermoplastic resin containing a predetermined amount of glass fiber is plasticized by a plasticizing / injection device, and carbon dioxide gas, nitrogen gas, etc. To obtain a foamed molten injection material in which a physical foaming agent is injected and dissolved, and inject it into a mold cavity and foam it while filling it, or use inert gas such as nitrogen gas, carbon dioxide gas, argon gas, etc. The gas is injected into the cavity of the mold under counter pressure, and then expanded to a volume corresponding to the molded product for which the cavity is to be obtained, and then foamed, or injected and filled, and then the cavity is obtained. Since the foam is expanded and expanded to a volume corresponding to the molded product to be molded, or injected, the injected foamed molten injection material is compressed, and then the cavity is removed. Since the foam is expanded to the volume corresponding to the molded product to be expanded and foamed, a glass fiber reinforced thermoplastic resin molded product having high strength, excellent surface appearance, no warpage, deformation, etc., and light weight can be obtained. .

[Brief description of the drawings]

FIG. 1 is a front elevational view showing a partial cross section of an embodiment of an injection molding apparatus used for carrying out a method of molding a glass fiber reinforced thermoplastic resin molded product according to the present invention.

FIG. 2 is a view showing a molding process according to the embodiment of the present invention. FIG. 2A is a sectional view of a mold showing a first molding process, and FIG. 2B is a cross-sectional view of a mold showing a second molding process.

FIG. 3 is a cross-sectional view of a mold showing a molding process according to a third embodiment of the present invention.

[Explanation of symbols]

KS Plasticizing and injection unit KA
Mold device 1 Screw cylinder 2
Gas supply hole 10 Inert gas supply device 20
Screw 31 Fixed mold 32
Recess 35 Movable mold 36
Core 40 Counter pressure adding device C1, C2 Cavity

Claims (6)

[Claims] 1. An injection material made of a thermoplastic resin containing a predetermined amount of glass fiber is plasticized by a plasticizing / injection device, and a physical blowing agent such as carbon dioxide gas and nitrogen gas is injected and dissolved. Molding method for molding a glass fiber reinforced thermoplastic resin, characterized in that a foamed molten injection material is obtained, and is injected into a mold cavity and foamed while being filled. 2. An injection material made of a thermoplastic resin containing a predetermined amount of glass fiber is plasticized by a plasticizing / injection device, and a physical blowing agent such as carbon dioxide gas and nitrogen gas is injected and dissolved. A foamed molten injection material is obtained, and is injected into a mold cavity under counter pressure by an inert gas such as nitrogen gas, carbon dioxide gas, or argon gas, and then molded to obtain the cavity. A method for forming a glass fiber reinforced thermoplastic resin molded product, which expands to a volume corresponding to the product and foams. 3. An injection material made of a thermoplastic resin containing a predetermined amount of glass fiber is plasticized by a plasticizing / injection device, and a physical blowing agent such as carbon dioxide gas and nitrogen gas is injected and dissolved. Obtained foam melt injection material, nitrogen gas, carbon dioxide gas, injection into a cavity of the mold that has been subjected to counter pressure by an inert gas such as argon gas, filling it, and then try to obtain the cavity A method for molding a glass fiber reinforced thermoplastic resin molded product, which expands and foams to a volume corresponding to the molded product to be molded. 4. An injection material made of a thermoplastic resin containing a predetermined amount of glass fiber is plasticized by a plasticizing / injection device, and a physical blowing agent such as carbon dioxide gas and nitrogen gas is injected and dissolved. Injected into a mold cavity that has been counter-pressured with an inert gas such as nitrogen gas, carbon dioxide gas, or argon gas, and the injected foamed molten injection material is compressed. And then expanding the foam to a volume corresponding to the molded product for which the cavity is to be obtained and foaming the molded product. 5. The molding method according to any one of claims 2 to 4, wherein when the foam is expanded to a volume corresponding to the molded product whose cavity is to be obtained and foamed, a counter pressure is also associated with the expansion. A method for forming a glass fiber reinforced thermoplastic resin molded product to be opened. 6. A glass fiber-reinforced thermoplastic resin molded article obtained by the molding method according to claim 1.