JP7370266B2 - Injection molding method and injection molding equipment - Google Patents

Description

INDUSTRIAL APPLICATION This invention can be suitably utilized for the injection molding method and injection molding apparatus, especially the injection molding method and injection molding apparatus which form a filler containing resin molding.

In recent years, resin composite materials using fillers (carbon fiber, etc.) have been attracting attention. In particular, attempts are being made to improve the mechanical strength of molded bodies by manufacturing molded bodies using resins containing fillers.

Such a composite material can be obtained by kneading a resin and a filler using a device equipped with a screw, such as an injection molding device or an extruder.

For example, Patent Document 1 discloses that the screw rotation speed when kneading a polymer blend sample in a molten state by a screw can be arbitrarily set in the range of 50 rpm to 3000 rpm, and a polymer blend film using an internal feedback screw is disclosed. A technique for manufacturing is disclosed. In this way, by employing an internal feedback screw, it is possible to produce a polymer blend film having a microscopically dispersed structure such as a co-continuous structure by kneading and extruding under high shear.

Japanese Patent Application Publication No. 2005-313608

The present inventor is engaged in the research and development of filler-containing resins using injection molding equipment and extruders, and is actively studying how to improve the reinforcing effect of resins by adding fillers.

A molded article made of such a filler-containing resin can be formed using an injection molding device. The injection molding device includes a cylinder and a screw rotatably disposed within the cylinder. For example, resin pellets supplied from a hopper into a cylinder are melted in the cylinder and sent forward by a screw, then a filler is added, the molten resin and filler are kneaded, and a predetermined amount of resin pellets is transferred from an injection molding machine to a molding machine. By injecting it into a mold, a molded article with a desired shape can be formed.

Here, in order to improve the mechanical strength of the molded product, it is necessary that the filler is uniformly dispersed in the resin, but when adding the filler after melting the resin pellets, it is necessary to Since the filler has to be added during the process, it may be difficult to secure sufficient time for kneading the molten resin and the filler.

Therefore, a technology is desired that improves the dispersibility of the filler contained in the molded body and produces a molded body with higher performance.

Other objects and novel features will become apparent from the description of this specification and the accompanying drawings.

The injection molding method disclosed in the present application includes (a) an injection molding device having a cylinder, a screw disposed in the cylinder, and a bypass passage connected to the cylinder; (b) supplying a resin material into the cylinder from a first supply port provided upstream of the cylinder and melting it to form a molten resin; (c) a step of supplying a filler from a second supply port provided downstream of the first supply port of the cylinder and kneading the molten resin and the filler to form the filler-containing molten resin; d) metering the filler-containing molten resin at the tip of the screw by retracting the screw such that the tip of the screw retreats by a first stroke from the first position to the second position; (e) injecting the filler-containing molten resin into the mold by advancing the screw, and the (c) step injects the filler-containing molten resin through the bypass channel. and returning from a first connection port to which one end of the bypass flow path is connected to a second connection port provided upstream of the first connection port to which the other end of the bypass flow path is connected.

The injection molding apparatus disclosed in the present application includes a cylinder, a screw disposed in the cylinder, and a bypass passage connected to the cylinder, and the cylinder is located upstream and is supplied with a resin material. a first supply port located downstream of the first supply port and to which the filler is supplied; a first connection port to which one end of the bypass flow path is connected; a second connection port to which the other end is connected, the first connection port is located downstream of the second connection port, and the second connection port is located downstream of the second supply port. do.

According to the injection molding method disclosed in this application, a resin molded article with good characteristics can be manufactured.

According to the injection molding apparatus disclosed in this application, a resin molded article with good characteristics can be manufactured.

1 is a diagram showing the configuration of a manufacturing apparatus (manufacturing system) for a filler-containing resin molded body according to a first embodiment. FIG. 2 is a diagram showing the internal configuration of an injection molding device. It is a figure showing the composition of a dalmage type screw. It is a figure showing the composition of the drive part of a screw. It is a typical sectional view showing an injection molding process of a study example. FIG. 3 is a schematic cross-sectional view showing an injection molding process according to the first embodiment. FIG. 3 is a schematic cross-sectional view showing an injection molding process according to the first embodiment. 5 is a graph showing changes in pressure at various parts of the cylinder during the kneading process of Embodiment 1. FIG. FIG. 7 is a schematic cross-sectional view showing an injection molding process according to a second embodiment. FIG. 7 is a schematic cross-sectional view showing an injection molding process according to a second embodiment. FIG. 7 is a schematic cross-sectional view showing an injection molding process in Embodiment 3. FIG. 7 is a schematic cross-sectional view showing an injection molding process in Embodiment 3.

Hereinafter, embodiments will be described in detail based on examples and drawings. In addition, in all the drawings for explaining the embodiment, members having the same function are given the same reference numerals, and repeated explanation thereof will be omitted.

(Embodiment 1)
In this embodiment, an injection molding method (a method for manufacturing a filler-containing resin molded body) will be described.

FIG. 1 is a diagram showing the configuration of a manufacturing apparatus (manufacturing system) for a filler-containing resin molded body according to the present embodiment. This device includes an injection molding device 1 and a press machine 5. In this embodiment, resin pellets (resin material) that do not contain filler and filler are directly mixed to form a molded body (molded body).

The injection molding apparatus 1 is an apparatus for melting supplied resin pellets RP and mixing and kneading them with a filler F to form a filler-containing molten resin (MRF). The injection molding apparatus 1 includes a cylinder 11 whose temperature is controlled by a temperature control means (not shown), a screw S disposed inside the cylinder 11, and a bypass flow path (bypass cylinder) 12 connected to the cylinder 11. ing. The screw S is controlled by a drive unit 17 provided at the rear end (upstream side) of the cylinder 11, and a discharge nozzle 19 is provided at the tip of the cylinder 11.

The cylinder 11 has a resin pellet RP supply port 13h and a filler F supply port (vent hole) 15h, which are arranged on the upstream side of the cylinder 11. The supply port 13h is connected to a hopper (supply device, charging device) 13 for resin pellets RP, and the supply port 15h is connected to a supply device 15 for filler F.

The cylinder 11 has connection ports 12ha and 12hb with the bypass flow path 12. The downstream connection port 12ha is connected to one end of the bypass flow path 12, and the upstream connection port 12hb is connected to the other end of the bypass flow path 12.

The temperature of the bypass passage 12 is controlled by a temperature control means (not shown), and connects the connection ports 12ha and 12hb of the cylinder 11. As described above, by providing the bypass flow path 12, the filler-containing molten resin (MRF) stored at the tip of the cylinder 11 can be returned to the upstream side of the cylinder 11 via the bypass flow path 12, and the molten resin can be returned to the upstream side of the cylinder 11. The filler-containing molten resin (MRF) is again kneaded by the screw in the cylinder 11 and transported toward the tip. In this way, the kneadability of the molten resin and filler F can be improved. In other words, the cylinder 11 and the bypass channel 12 can be circulated between the connection ports 12ha and 12hb, and the kneading performance of the molten resin and the filler F can be improved. This makes it possible to produce a resin molded article with good properties, such as good filler dispersibility.

A valve 12Ba is provided between the connection port 12ha and the bypass flow path 12, and a valve 12Bb is provided between the connection port 12hb and the bypass flow path 12. By opening the valves (12Ba, 12Bb), the cylinder 11 and the bypass flow path 12 are brought into a connected state, and by closing the valves (12Ba, 12Bb), the cylinder 11 and the bypass flow path 12 are cut off. For example, the valves (12Ba, 12Bb) are opened in the process of kneading the molten resin and filler F, and the valves (12Ba, 12Bb) are closed in the process of measuring the kneaded material and the injection process.

As the valve, for example, a gate valve, a globe bubble, a ball valve, etc. can be used.

The press machine 5 has, for example, a first mold SL and a second mold SR, and a filler-containing molten resin MRF is injected (injected, discharged) into the gap between them and solidified in a shape corresponding to the mold. By doing so, a molded body is formed.

FIG. 2 is a diagram showing the internal configuration of the injection molding apparatus. As shown in FIG. inserted and built-in.

In FIG. 2, the screw S is mainly composed of a full-flight screw provided with a spiral projection (thread). The screw S has a plurality of screw parts (screw pieces). Specifically, it has a plurality of screw parts with different groove depths (projection heights). For example, the screw S1 on the upstream side (hopper 13 side) includes a screw portion S1a and a screw portion S1b having a shallower groove than the screw portion S1a. Further, the screw S2 on the downstream side (discharge nozzle 19 side) has a screw portion S2a and a screw portion S2b having a shallower groove than the screw portion S2a. The upstream screw S1 is arranged from the supply port 13h to the supply port 15h, and the downstream screw S2 is arranged upstream from the supply port 15h. Such a screw configuration is sometimes referred to as a two-stage type. Note that here, a portion (piece) having a sharp shape toward the tip is arranged at the tip of the screw S.

In the screw part S1a corresponding to the supply part (13h) of the resin pellets RP, it is preferable to use a screw part with a deep groove in order to secure the volume, and in the screw part S1b through which the molten resin passes, In order to improve kneading properties and prevent the molten resin from flowing out (venting up) from the supply port 15h, it is preferable to use a screw portion with a shallow groove.

In addition, in the screw part S2a corresponding to the supply part (15h) of filler F, it is preferable to make the groove deep and create a starvation state, and in the screw part S2b through which the kneaded material of molten resin and filler F passes, In order to improve the kneading properties of the resin, it is preferable to use a screw portion with shallow grooves.

Although a full-flight screw (screw portion) is used in FIG. 2, screws of other shapes (screw portion) may be used. For example, in the screw portion S2b, a dalmage type screw may be used to improve kneading performance. FIG. 3 is a diagram showing the configuration of a Dalmage type screw. 3(B) and FIG. 3(C) correspond to the BB cross section and the CC cross section of FIG. 3(A), respectively. A plurality of annular irregularities each having a width L _F are arranged at a distance L _T . The convex portions are arranged at predetermined intervals around the screw (FIG. 3(B)). D is the screw diameter and L is the screw length. In addition to the Dalmage type screw, examples of screws with high kneading properties include Maddock type, pin type, and static mixer type screws. In particular, in the screw part S2b, by using a screw with high kneading properties (kneading piece, high kneading piece) and arranging it so as to overlap with the bypass flow path 12, the molten resin containing the filler can be passed through the bypass flow path 12. During the circulation, the kneading properties are further improved, and the kneading properties of the molten resin and the filler F can be further improved.

FIG. 4 is a diagram showing the configuration of the screw driving section. As shown in FIG. 4, the screw S is connected to a line drive mechanism 17L that moves the screw S forward or backward, and a rotation drive mechanism 17R that rotates the screw S. Further, a load cell (sensor) 17S is provided between the line drive mechanism 17L and the screw S to detect the load (back pressure) that the screw S receives in the axial direction. The line drive mechanism 17L and the rotation drive mechanism 17R are controlled by a screw control section 17C. For example, based on a signal from the load cell 17S, the screw S is controlled to advance, retreat, or fix its position.

Further, the supply amount and supply timing (supply period) of the resin pellets RP, and the supply amount and supply timing (supply period) of the filler F can be controlled by the material control unit 15c (see FIG. 2). For example, the timing of supplying the filler F may be adjusted by providing a sensor (for example, a laser displacement meter) 15s above the supply port 15h and detecting the timing of passage of the molten resin. Furthermore, the timing of supply of the filler F may be adjusted by providing a pressure sensor in the cylinder near the supply port 15h and detecting changes in the pressure applied to the cylinder due to passage of the molten resin. In this way, by timing the supply of filler F, it is possible to add an appropriate amount of filler corresponding to the supply amount of resin pellets RP, and the mixing ratio of resin and filler can be adjusted with precision. .

FIG. 5 is a schematic cross-sectional view showing the injection molding process of the studied example. As shown in FIG. 5(A), the resin pellets RP supplied from the hopper through the supply port are melted in the cylinder 11, and are transferred downstream while being stirred by the screw. Then, filler F is supplied into the molten resin from the filler F supply port, and a mixture of the molten resin and filler F is transferred to the tip of the cylinder 11 and stored. In this way, when the amount of kneaded material of the molten resin and filler F stored at the tip of the cylinder 11 increases, a force pushing it back to the screw (retreating force) acts. This force is called "back pressure" and corresponds to the load cell output (signal) mentioned above.

The amount of kneaded material stored can be determined by such an increase in back pressure, and after reaching a predetermined back pressure (for example, 5 MPa), the line drive mechanism (17L) is activated as shown in FIG. 5(B). After retracting the screw S and storing (measuring) a predetermined amount of kneaded material at the tip of the cylinder 11, by moving the screw S forward, a predetermined amount of kneaded material is transferred from the discharge nozzle to the mold (press machine 5). Can be discharged.

However, in the injection molding process of the above study example (FIG. 5), the dispersibility of filler F may be low.

Therefore, in this embodiment, a bypass flow path 12 is provided at the tip of the cylinder 11 to return the filler-containing molten resin (MRF) stored at the tip of the cylinder 11 to the upstream side of the cylinder 11. The dispersibility of the filler F can be improved by kneading it many times using the screw in the cylinder 11. This will be explained in detail below.

6 and 7 are schematic cross-sectional views showing the injection molding process of this embodiment.

First, the first kneading and discharging process will be described with reference to FIG. As shown in FIG. 6(A), resin pellets RP are supplied from the supply port 13h corresponding to the hopper 13 on the upstream side of the cylinder 11. The supply amount here is "W1+α". W1 is the supply amount corresponding to one discharge amount, and α is the supply amount corresponding to the retention amount (the amount of material remaining inside the cylinder 11 after discharge). At this time, the tip T of the screw S is located at the first position P0, which is the most downstream of the cylinder 11. At this first position P0, the screw S is rotated. At this time, the resin pellets RP supplied into the cylinder 11 are gradually melted by the heat from the cylinder 11 and the shear force caused by the rotation of the screw S, become molten resin, and are transported downstream. Note that here, the rotation direction of the screw S is the first direction (the direction in which the molten resin is conveyed downstream). Further, at this time, the valves 12Ba and 12Bb are closed.

Next, as shown in FIG. 6(B), the filler F is supplied when the molten resin (RP) is conveyed to the filler F supply port 15h. Let the supply amount be "WF1+β". At this time, the supply of resin pellets RP is stopped, and the molten resin located between the supply port 15h and the supply port 13h of the cylinder 11 is in an amount corresponding to the above supply amount (W1 + retention amount (α)). be. Note that the stoppage of the supply of the resin pellets RP (stoppage period) is not limited to this timing.

Furthermore, when the screw S continues to rotate, the kneaded material of the molten resin and the filler F is conveyed to the downstream side of the cylinder 11, as shown in FIG. 6(C). Then, as shown in FIG. 6(D), the kneaded material reaches the tip T of the screw S. Thereafter, the kneaded material reaches the tip T of the screw S at any time, and as the stored amount increases, the back pressure of the screw S increases accordingly. For example, the back pressure of the screw S reaches the first specified value (for example, 5 MPa).

Then, valves 12Ba and 12Bb are opened. At this time, as described above, since the kneaded material of the molten resin and the filler F is stored on the downstream side of the cylinder 11, the back pressure of the screw S is the first specified value (for example, 5 MPa). By opening the valve 12Ba, the mixture of the molten resin and the filler F flows into the bypass passage 12, and is returned to the region of the cylinder 11 where the pressure is lower via the valve 12Bb. Then, the kneaded product of the molten resin and filler F is transported to the tip of the cylinder while being kneaded by the screw again, and flows into the bypass passage 12 from the valve 12Ba again. In this way, between the valves 12Ba and 12Bb, the kneaded material of the molten resin and the filler F circulates through the cylinder 11 and the bypass channel (FIG. 6(E)).

Then, valves 12Ba and 12Bb are closed. As shown in FIG. 6(F), the screw S is moved back by a distance (first stroke, between P0 and P1, for example, 60 mm) corresponding to one discharge amount (1S) (measuring step). When the screw S is retracted, the rotation direction of the screw S is the first direction.

Next, the screw S is advanced (injection step). At this time, the rotation of the screw S is in a stopped state. As a result, a mixture of molten resin and filler F stored at the tip of the screw S is discharged from the discharge nozzle toward the press 5 (see FIG. 1).

Note that the one-time discharge amount (1S) in the injection process may be smaller than the amount of kneaded material stored at the tip of the screw S. Further, the size of the shaded area showing the molten resin in FIG. 6 is for explaining this embodiment in an easy-to-understand manner, and may differ depending on the relationship with the actual scale of the screw S and the cylinder 11. . For example, the gap between the screw S and the cylinder 11 is about 1 mm, and in the entire process shown in FIG. 6, the kneaded material stored at the tip of the screw S (at least during the first stroke) is not filled. be. In other words, no voids are formed (no starvation state occurs).

Next, the second and subsequent kneading and discharging steps will be described with reference to FIG.

First, the valves 12Ba and 12Bb are opened, and the resin pellets RP are supplied from the supply port 13h corresponding to the hopper 13 on the upstream side of the cylinder 11, as shown in FIG. 7(A). The supply amount here is W1. At this time, the tip T of the screw S is located at the first position P0, which is the most downstream of the cylinder 11. At this first position P0, the screw S is rotated. At this time, the resin pellets RP supplied into the cylinder 11 are gradually melted by the heat from the cylinder 11 and the shear force caused by the rotation of the screw S, become molten resin, and are transported downstream. Note that here, the rotation direction of the screw S is the first direction.

Next, as shown in FIG. 7(B), the filler F is supplied when the molten resin (RP) is conveyed to the filler F supply port 15h. Let the supply amount be WF1. At this time, the supply of the resin pellets RP is stopped, and the amount of molten resin located between the supply ports 15h and 13h of the cylinder 11 corresponds to the supply amount W1. Note that the stoppage of the supply of the resin pellets RP (stoppage period) is not limited to this timing.

Furthermore, when the screw S continues to rotate, the kneaded material of the molten resin and the filler F is conveyed to the downstream side of the cylinder 11, as shown in FIG. 7(C). Then, as shown in FIG. 7(D), the kneaded material reaches the tip T of the screw S. Thereafter, the kneaded material reaches the tip T of the screw S at any time, and as the stored amount increases, the back pressure of the screw S increases accordingly. For example, the back pressure of the screw S reaches the first specified value (for example, 5 MPa).

At this time, as described above, since the kneaded material of the molten resin and the filler F is stored on the downstream side of the cylinder 11, the back pressure of the screw S is the first specified value (for example, 5 MPa). The kneaded mixture of molten resin and filler F flows into the bypass flow path 12 through the opened valve 12Ba, and is returned to the region of the cylinder 11 where the pressure is lower through the valve 12Bb. Then, the kneaded product of the molten resin and filler F is transported to the tip of the cylinder while being kneaded by the screw again, and flows into the bypass passage 12 from the valve 12Ba again. In this way, between the valves 12Ba and 12Bb, the kneaded material of the molten resin and the filler F circulates through the cylinder 11 and the bypass channel (FIG. 7(E)).

Next, the valves 12Ba and 12Bb are closed, and as shown in FIG. 7(F), the screw S is retreated by a distance (first stroke, for example, 60 mm) corresponding to one discharge amount (1S) (measuring step). . When the screw S is retracted, the rotation direction of the screw S is the first direction.

Next, the screw S is advanced (injection step). At this time, the rotation of the screw S is in a stopped state. As a result, a mixture of molten resin and filler F stored at the tip of the screw S is discharged from the discharge nozzle toward the press 5 (see FIG. 1). In this way, the second kneading and discharging is performed, and thereafter the above steps are repeated.

FIG. 8 is a graph showing changes in pressure at various parts of the cylinder during the kneading process of this embodiment. The vertical axis of the graph is pressure [MPa], and the horizontal axis is cylinder position.

As shown in FIG. 8, the filler F supply section (15h) is in a starvation state, so the pressure inside the cylinder is 0 MPa (gauge pressure, pressure difference from atmospheric pressure). Since the molten resin (here, the molten resin containing filler) is gradually filled from this position to the downstream side, the pressure gradually increases and reaches its maximum near the screw portion S2b. Then, the pressure gradually decreases toward the tip of the cylinder 11.

Therefore, the connection port 12ha, which is the starting point on the downstream side of the bypass channel 12, is preferably provided in the vicinity of the screw portion S2b, and, for example, is preferably provided at the position where the pressure is maximum or downstream from this. The connection port 12hb, which is the starting point on the upstream side of the bypass flow path 12, is preferably provided near the opening (15h), for example, at a position where the molten resin is kneaded in a non-filled state, or at the location mentioned above. It is preferable to provide it upstream of the position where the pressure is maximum. By providing the starting points (12ha, 12hb) of the bypass flow path 12 in this way, the molten resin inside the cylinder 11 can quickly flow from the downstream start point (connection port 12ha) of the bypass flow path 12 to the upstream start point (connection port 12hb). The molten resin can be returned and efficiently circulated. Thereby, the kneading properties of the molten resin can be improved. The pressure difference between the upstream starting point (connection port 12hb) and the downstream starting point (connection port 12ha) is preferably 1 MPa or more.

As described above, in this embodiment, the filler-containing molten resin (MRF) stored at the tip of the cylinder 11 is returned to the upstream side of the cylinder 11 via the bypass channel 12, so that the filler F is dispersed. can improve sex.

Note that the supply amount W1 is an amount corresponding to the one-time discharge amount, but it does not need to be a fixed amount, and as the retention amount may change as the discharge is repeated, the supply amount W1 may be adjusted within a predetermined range. may be adjusted.

Although there are no restrictions on the resin and filler used in this embodiment, for example, those shown below can be used.

As the resin, a thermoplastic resin can be used. As the thermoplastic resin, for example, polyethylene, polypropylene, polyamide, polyethylene terephthalate, polyimide, polyether ether ketone, etc. can be used. These resins may be used alone or in a mixture of multiple types.

As the filler, for example, carbon fiber, glass fiber, aramid fiber, natural fiber, etc. can be used. Examples of carbon fibers (carbon-based materials) include carbon fibers, carbon nanofibers, carbon nanotubes, fullerenes, graphene, and carbon black. Examples of glass fibers include silica and alumina. Examples of aramid fibers include para-aramid fibers and meta-aramid fibers. Examples of natural fibers include cellulose (including cellulose nanofibers), ramie, jute, kenaf, bamboo, and bagasse. These fillers may be used alone or in combination of two or more.

Furthermore, a filler that has been surface-treated may also be used. By performing the surface treatment in this manner, the fibrillation properties of the filler are improved and the affinity with the resin is improved.

(Embodiment 2)
In Embodiment 1, filler F was added to resin pellets RP that do not contain filler, but mixed pellets may be used as the raw material. The mixed pellet is a mixture of filler-free natural pellets NP and filler-containing pellets FP. In such a case, it is not necessary to separately add filler F, but as in Embodiment 1, it is necessary to improve kneadability in order to improve the dispersibility of the filler.

9 and 10 are schematic cross-sectional views showing the injection molding process of this embodiment. In the injection molding method of this embodiment, detailed explanations of steps similar to those of Embodiment 1 will be omitted.

First, the first kneading and discharging process will be described with reference to FIG. As shown in FIG. 9(A), mixed pellets (NP, FP) are supplied in a supply amount W1+α' from the supply port 13h corresponding to the hopper 13 on the upstream side of the cylinder 11. At this time, the tip T of the screw S is at the most downstream position P0 of the cylinder 11. At this position P0, the screw S is rotated. At this time, the mixed pellets (NP, FP) supplied into the cylinder 11 are gradually melted by the heat from the cylinder 11 and the shear force caused by the rotation of the screw S, and the molten resin and filler F are mixed together. It becomes a material and is transported downstream. Note that here, the rotational direction of the screw S is assumed to be the first direction (the direction in which the screw advances). Further, at this time, the valves 12Ba and 12Bb are closed.

Next, as shown in FIG. 9(B), the kneaded mixture of molten resin and filler F is conveyed to the vent hole 15v. Gas and the like in the molten resin are released from this vent hole 15v. At this time, the supply of mixed pellets (NP, FP) as raw materials is stopped, and the kneaded material of the molten resin and filler F located between the vent hole 15v of the cylinder 11 and the supply port 13h is (W1+α'), W1 is the supply amount corresponding to one discharge amount, and α' corresponds to the retention amount (the amount of material remaining inside the cylinder 11 after discharge). It is the amount of supply.

Furthermore, when the screw S continues to rotate, the kneaded material of the molten resin and the filler F is conveyed to the downstream side of the cylinder 11, as shown in FIG. 9(C). Then, as shown in FIG. 9(D), the kneaded material reaches the tip T of the screw S. Thereafter, the kneaded material reaches the tip T of the screw S at any time, and as the stored amount increases, the back pressure of the screw S increases accordingly. For example, the back pressure of the screw S reaches the first specified value (for example, 5 MPa).

Then, valves 12Ba and 12Bb are opened. At this time, as described above, since the kneaded material of the molten resin and the filler F is stored on the downstream side of the cylinder 11, the back pressure of the screw S is the first specified value (for example, 5 MPa). By opening the valve 12Ba, the mixture of the molten resin and the filler F flows into the bypass passage 12, and is returned to the region of the cylinder 11 where the pressure is lower via the valve 12Bb. Then, the kneaded product of the molten resin and filler F is transported to the tip of the cylinder while being kneaded by the screw again, and flows into the bypass passage 12 from the valve 12Ba again. In this way, between the valves 12Ba and 12Bb, the kneaded material of the molten resin and the filler F circulates through the cylinder 11 and the bypass channel (FIG. 9(E)).

Next, as shown in FIG. 9F, the screw S is moved back by a distance (first stroke, for example, 60 mm) corresponding to one discharge amount (1S) (measuring step). When the screw S is retracted, the rotation direction of the screw S is the first direction.

Next, the screw S is advanced (injection step). At this time, the rotation of the screw S is in a stopped state. As a result, a mixture of molten resin and filler F stored at the tip of the screw S is discharged from the discharge nozzle toward the press 5 (see FIG. 1).

Next, the second and subsequent kneading and discharging steps will be described with reference to FIG.

First, the valves 12Ba and 12Bb are opened, and mixed pellets (NP, FP) are supplied in the supply amount W1 from the supply port 13h corresponding to the hopper 13 on the upstream side of the cylinder 11, as shown in FIG. 10(A). At this time, the tip T of the screw S is located at the first position P0, which is the most downstream of the cylinder 11. At this first position P0, the screw S is rotated. At this time, the mixed pellets (NP, FP) supplied into the cylinder 11 are gradually melted by the heat from the cylinder 11 and the shear force caused by the rotation of the screw S, and become molten resin, which flows downstream. transported. Note that here, the rotation direction of the screw S is the first direction.

Next, as shown in FIG. 10(B), the kneaded mixture of molten resin and filler F is conveyed to the vent hole 15v. Gas and the like in the molten resin are released from this vent hole 15v. At this time, the supply of mixed pellets (NP, FP) as raw materials is stopped, and the kneaded material of the molten resin and filler F located between the vent hole 15v of the cylinder 11 and the supply port 13h is This is the amount corresponding to the amount W1.

Furthermore, when the screw S continues to rotate, the kneaded material of the molten resin and the filler F is conveyed to the downstream side of the cylinder 11, as shown in FIG. 10(C). Then, as shown in FIG. 10(D), the kneaded material reaches the tip T of the screw S. Thereafter, the kneaded material reaches the tip T of the screw S at any time, and as the stored amount increases, the back pressure of the screw S increases accordingly. For example, the back pressure of the screw S reaches the first specified value (for example, 5 MPa).

At this time, as described above, since the kneaded material of the molten resin and the filler F is stored on the downstream side of the cylinder 11, the back pressure of the screw S is the first specified value (for example, 5 MPa). The mixture of molten resin and filler F flows into the bypass passage 12 and is returned to the region of the cylinder 11 where the pressure is lower via the valve 12Bb. Then, the kneaded product of the molten resin and filler F is transported to the tip of the cylinder while being kneaded by the screw again, and flows into the bypass passage 12 from the valve 12Ba again. In this way, between the valves 12Ba and 12Bb, the kneaded material of the molten resin and the filler F circulates through the cylinder 11 and the bypass channel (FIG. 10(E)).

Next, the valves 12Ba and 12Bb are closed, and as shown in FIG. 10(F), the screw S is retreated by a distance (first stroke, for example, 60 mm) corresponding to one discharge amount (1S) (measuring step). . When the screw S is retracted, the rotation direction of the screw S is the first direction.

Next, the screw S is advanced (injection step). At this time, the rotation of the screw S is in a stopped state. As a result, a mixture of molten resin and filler F stored at the tip of the screw S is discharged from the discharge nozzle toward the press 5 (see FIG. 1). In this way, the second kneading and discharging is performed, and thereafter the above steps are repeated.

In this manner, also in this embodiment, the filler-containing molten resin (MRF) stored at the tip of the cylinder 11 is returned to the upstream side of the cylinder 11 via the bypass channel 12, so that the filler F is dispersed. can improve sex.

(Embodiment 3)
In the second embodiment, a two-stage injection molding apparatus in which the vent hole 15v was provided in the middle of the cylinder was used, but a one-stage injection molding apparatus without a vent hole may also be used. Here, the screw S1 is composed of a screw portion S2a and a screw portion S1a.

11 and 12 are schematic cross-sectional views showing the injection molding process of this embodiment. In the injection molding method of this embodiment, detailed explanations of steps similar to those of Embodiment 1 will be omitted.

First, the first kneading and discharging process will be described with reference to FIG. 11.

First, as shown in FIG. 11A, mixed pellets (NP, FP) are supplied in a supply amount W1 from the supply port 13h corresponding to the hopper 13 on the upstream side of the cylinder 11. At this time, the tip T of the screw S is at the most downstream position P0 of the cylinder 11. At this position P0, the screw S is rotated. At this time, the mixed pellets (NP, FP) supplied into the cylinder 11 are gradually melted by the heat from the cylinder 11 and the shear force caused by the rotation of the screw S, and the molten resin and filler F are mixed together. It becomes a material and is transported downstream. Note that here, the rotation direction of the screw S is the first direction. Further, at this time, the valves 12Ba and 12Bb are closed.

Next, as shown in FIG. 11(B), the molten resin (NP, FP, kneaded product of the molten resin and filler F) is conveyed to the downstream side of the cylinder 11, and the kneaded product reaches the tip T of the screw S. . Thereafter, the kneaded material reaches the tip T of the screw S at any time, and as the stored amount increases, the back pressure of the screw S increases accordingly. For example, the back pressure of the screw S reaches the first specified value (for example, 5 MPa).

Then, valves 12Ba and 12Bb are opened. At this time, as described above, since the kneaded material of the molten resin and the filler F is stored on the downstream side of the cylinder 11, the back pressure of the screw S is the first specified value (for example, 5 MPa). By opening the valve 12Ba, the mixture of the molten resin and the filler F flows into the bypass passage 12, and is returned to the region of the cylinder 11 where the pressure is lower via the valve 12Bb. Then, the kneaded product of the molten resin and filler F is transported to the tip of the cylinder while being kneaded by the screw again, and flows into the bypass passage 12 from the valve 12Ba again. In this way, between the valves 12Ba and 12Bb, the kneaded material of the molten resin and the filler F circulates through the cylinder 11 and the bypass channel (FIG. 11(C)).

Next, the valves 12Ba and 12Bb are closed, and as shown in FIG. 11(D), the screw S is retreated by a distance (first stroke, for example, 60 mm) corresponding to one discharge amount (1S) (measuring step). . When the screw S is retracted, the rotation direction of the screw S is the first direction.

Next, the screw S is advanced (injection step). At this time, the rotation of the screw S is in a stopped state. As a result, a mixture of molten resin and filler F stored at the tip of the screw S is discharged from the discharge nozzle toward the press 5 (see FIG. 1).

Next, with reference to FIG. 12, the steps up to the second and subsequent kneading and discharge will be described.

First, the valves 12Ba and 12Bb are opened, and mixed pellets (NP, FP) are supplied in the supply amount W1 from the supply port 13h corresponding to the hopper 13 on the upstream side of the cylinder 11, as shown in FIG. 12(A). At this time, the tip T of the screw S is located at the first position P0, which is the most downstream of the cylinder 11. At this first position P0, the screw S is rotated. At this time, the mixed pellets (NP, FP) supplied into the cylinder 11 are gradually melted by the heat from the cylinder 11 and the shear force caused by the rotation of the screw S, and become molten resin, which flows downstream. transported. Note that here, the rotation direction of the screw S is the first direction.

Next, as shown in FIG. 12(B), the kneaded product of the molten resin and filler F is conveyed to the downstream side of the cylinder 11. Then, the kneaded material reaches the tip T of the screw S. Thereafter, the kneaded material reaches the tip T of the screw S at any time, and as the stored amount increases, the back pressure of the screw S increases accordingly. For example, the back pressure of the screw S reaches the first specified value (for example, 5 MPa).

At this time, as described above, since the kneaded material of the molten resin and the filler F is stored on the downstream side of the cylinder 11, the back pressure of the screw S is the first specified value (for example, 5 MPa). The mixture of molten resin and filler F flows into the bypass passage 12 and is returned to the region of the cylinder 11 where the pressure is lower via the valve 12Bb. Then, the kneaded product of the molten resin and filler F is transported to the tip of the cylinder while being kneaded by the screw again, and flows into the bypass passage 12 from the valve 12Ba again. In this way, between the valves 12Ba and 12Bb, the kneaded material of the molten resin and the filler F circulates through the cylinder 11 and the bypass channel (FIG. 12(C)).

Next, the valves 12Ba and 12Bb are closed, and as shown in FIG. 12(D), the screw S is retreated by a distance (first stroke, for example, 60 mm) corresponding to one discharge amount (1S) (measuring step). . When the screw S is retracted, the rotation direction of the screw S is the first direction.

Next, the screw S is advanced (injection step). At this time, the rotation of the screw S is in a stopped state. As a result, a mixture of molten resin and filler F stored at the tip of the screw S is discharged from the discharge nozzle toward the press 5 (see FIG. 1). In this way, the second kneading and discharging is performed, and thereafter the above steps are repeated.

In this manner, also in this embodiment, the filler-containing molten resin (MRF) stored at the tip of the cylinder 11 is returned to the upstream side of the cylinder 11 via the bypass channel 12, so that the filler F is dispersed. can improve sex.

(Application example)
In the second and third embodiments described above, mixed pellets of natural pellets NP and filler-containing pellets FP were used as the raw material, but only natural pellets NP, two or more types of natural pellets NP with different resins, or , filler-containing pellets FP alone may be used. Even when a single material or a plurality of materials are used in this way, it is necessary to improve the kneading properties in order to homogenize the resin temperature and make the resins homogeneous. Therefore, even when using such a material, it is preferable to use the injection molding method and injection molding apparatus of Embodiments 2 and 3.

As above, the invention made by the present inventor has been specifically explained based on the embodiments and examples, but the present invention is not limited to the above embodiments or examples, and within the scope of the gist thereof. It goes without saying that various changes are possible.

1 Injection molding device 5 Press machine 11 Cylinder 12 Bypass flow path 12Ba Valve (valve)
12Bb valve
12ha Connection port 12hb Connection port 13 Hopper 13h Supply port 15 Filler supply device 15c Material control section 15h Supply port 15v Vent hole 17 Drive section 17C Screw control section 17L Line drive mechanism 17R Rotation drive mechanism 17S Load cell 19 Discharge nozzle F Filler FP Filler-containing pellet MRF Filler-containing molten resin NP Natural pellet RP Resin pellet S Screw S1 Screw S1a Screw part S1b Screw part S2 Screw S2a Screw part S2b Screw part SL 1st type SR 2nd type T Tip

Claims (12)

(a) A step of preparing an injection molding device having a cylinder, a screw disposed in the cylinder, a bypass passage connected to the cylinder, and a mold connected to the tip of the injection molding device. ,
(b) supplying a resin material into the cylinder from a first supply port provided upstream of the cylinder and melting it to form a molten resin;
(c) A filler is supplied from a second supply port provided downstream of the first supply port of the cylinder, and the molten resin and the filler are kneaded to form the filler-containing molten resin. process,
(d) Measuring the filler-containing molten resin at the tip of the screw by retracting the screw so that the tip of the screw retreats by a first stroke from the first position to the second position. ,
(e) injecting the filler-containing molten resin into the mold by advancing the screw;
In the step (c), the filler-containing molten resin is passed through the bypass flow path from a first connection port to which one end of the bypass flow path is connected to which the other end of the bypass flow path is connected; An injection molding method including a step of returning the first connection port to a second connection port provided upstream. In the injection molding method according to claim 1,
In the step (c), the pressure of the cylinder of the second connection port is lower than the pressure of the cylinder of the first connection port. In the injection molding method according to claim 1,
In the step (c), a first valve between the first connection port and the bypass flow path and a second valve between the second connection port and the bypass flow path are in an open state,
In the step (d), the first valve between the first connection port and the bypass flow path and the second valve between the second connection port and the bypass flow path are in a closed state. Molding method. (a) A step of preparing an injection molding device having a cylinder, a screw disposed in the cylinder, a bypass passage connected to the cylinder, and a mold connected to the tip of the injection molding device. ,
(b) supplying a resin material into the cylinder from a supply port provided upstream of the cylinder and melting it to form a molten resin;
(c) measuring the molten resin at the tip of the screw by retracting the screw so that the tip of the screw retreats by a first stroke from the first position to the second position;
(d) injecting the molten resin into the mold by advancing the screw;
In the step (b), the filler-containing molten resin is passed through the bypass flow path from a first connection port to which one end of the bypass flow path is connected to the first connection port to which the other end of the bypass flow path is connected. An injection molding method including a step of returning the first connection port to a second connection port provided upstream. In the injection molding method according to claim 4,
In the step (b), the pressure of the cylinder of the second connection port is lower than the pressure of the cylinder of the first connection port. In the injection molding method according to claim 4,
In the step (b), a first valve between the first connection port and the bypass flow path and a second valve between the second connection port and the bypass flow path are in an open state,
In the step (c), the first valve between the first connection port and the bypass flow path and the second valve between the second connection port and the bypass flow path are in a closed state. Molding method. comprising a cylinder, a screw disposed within the cylinder, and a bypass flow path connected to the cylinder,
The cylinder is connected to a first supply port located upstream to which the resin material is supplied, a second supply port located downstream of the first supply port to which the filler is supplied, and one end of the bypass flow path. a first connection port connected to the other end of the bypass flow path, and a second connection port connected to the other end of the bypass flow path;
The first connection port is located downstream of the second connection port, and the second connection port is located downstream of the second supply port ,
The bypass flow path is an injection molding device used for returning the resin material containing the filler kneaded in the cylinder from the first connection port to the second connection port. The injection molding apparatus according to claim 7,
a first valve between the first connection port and the bypass flow path;
An injection molding apparatus comprising a second valve between the second connection port and the bypass flow path. The injection molding apparatus according to claim 7,
The injection molding apparatus includes a kneading piece on the screw at a position between the first connection port and the second connection port. The injection molding apparatus according to claim 9,
In the injection molding apparatus, the kneading piece is of a Dalmage type, a Maddock type, a pin type, or a static mixer type. comprising a cylinder, a screw disposed within the cylinder, and a bypass flow path connected to the cylinder,
The cylinder includes a first supply port located upstream to which the resin material is supplied, a vent hole located downstream from the first supply port, and a first connection port to which one end of the bypass flow path is connected. a second connection port to which the other end of the bypass flow path is connected;
The first connection port is located downstream of the second connection port, and the second connection port is located downstream of the vent hole ,
In an injection molding apparatus, the bypass flow path is used to return the resin material kneaded in the cylinder from the first connection port to the second connection port. comprising a cylinder, a screw disposed within the cylinder, and a bypass flow path connected to the cylinder,
The cylinder has a first supply port located upstream to which the resin material is supplied, a first connection port to which one end of the bypass flow path is connected, and a second connection to which the other end of the bypass flow path is connected. having a mouth;
The first connection port is located downstream from the second connection port ,
In an injection molding apparatus, the bypass flow path is used to return the resin material kneaded in the cylinder from the first connection port to the second connection port.

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