JP3190917B2 - Injection molding method, injection mold and injection molded product - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for injection molding a thermoplastic resin, a mold for injection molding, and an injection molded product.

[0002]

2. Description of the Related Art Molecules and fillers in injection molded articles are easily oriented in the direction of resin flow during filling. In particular, the tendency is remarkable in a thin-walled molded product. Therefore, in order to change the orientation to an arbitrary direction, the resin flow direction at the time of filling is controlled by changing the position and size of the gate, or by designing the shape of a molded product. However, it is impossible to provide a plurality of orientations in any direction only by these techniques.

[0003]

The intensity in the direction orthogonal to the orientation direction is extremely low as compared with the orientation direction. For this reason, it has been pointed out that a thin plate-shaped molded product has insufficient strength in a direction orthogonal to the orientation direction. The shrinkage in the direction perpendicular to the orientation direction is larger than the shrinkage in the orientation direction,
This is one factor that causes deformation such as warpage.

[0004]

According to the present invention, a gate for filling a resin is provided at one side edge of a cavity, and the gate is injected.
An injection mold having an openable / closable resin reservoir communicated with the cavity on one side intersecting the filling direction and a variable-capacity resin reservoir communicated with the cavity on the other side; In injection molding of thermoplastic resin using a mold, immediately after injection filling of molten resin into the cavity, resin pressure is applied from one side of the cavity to the other side in a direction crossing the injection filling direction, and the core layer is During the unsolidification , the core layer is caused to flow in the direction in which the resin pressure acts, and the core layer
The injection molding method of Ru brought oriented in the direction, by the method, in the injection-molded article having a layer allowed crossed orientation and skin layers.

[0005]

According to the method and apparatus of the present invention, a layer having an orientation crossing the skin layer can be provided, and a molded article having a different orientation has reduced anisotropy and warpage and has a reduced strength. High deformation and low deformation.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example in which an injection molding method, an injection molding die and an injection molded product according to the present invention are implemented in a thin plate-like case lid will be described with reference to the drawings. First, the mold for injection molding will be described. A cavity 2 is formed in the mold 1, and a slit-shaped gate 3 as an injection port is opened on one side of the cavity 2. The gate 3 is commonly referred to as a film gate, it is communicated with the sprue 3b through the runners 3a, to uniformly and injected and filled at high speed molten resin into the cavity 2

In the mold 1, resin pools 4 and 5 communicating with the cavity 2 are formed on adjacent sides orthogonal to the side where the gate 3 is provided. One of the resin reservoirs 4 is composed of a blank 6 recessed in the inner wall of the cavity 2 and a block body 7 pushed into the blank 6, and has a volume depending on the amount of pushing of the block body 7. Can be controlled. And the other resin pool 5
Is a blank 8 recessed next to the cavity 2
And a block body 10 pressed into the blank 8 by a spring 9 and a pushing rod 11 for pushing the block body 10 out of the blank 8 against the pressing force of the spring 9. The pushing operation and the pushing operation are performed by the piston rod 1
2 in conjunction with the extruding operation, and both resin pools 4, 5
Are the same.

Using such a mold, the molten resin M is first injected into the cavity 2 (FIG. 2), and the operation of pushing the block 7 and pushing the block 10 into the resin reservoirs 4 and 5 is performed immediately (FIG. 2). 3 and 4). The molecules of the injected resin are oriented in the injection filling direction, and the skin layer in contact with the inner surface of the cavity 2 is instantaneously solidified. Although the molecules of the core layer sandwiched between the skin layers are also oriented in the injection direction, while the core layer is in an unsolidified state, the block body 7 is pushed into the blank 6 by the operation of pushing out the piston rod 12.
The resin in the blank 6 is pushed back into the cavity 2 by operating the block body 10 and the block body 10 is
The core layer flows in a direction perpendicular to the injection filling direction and is oriented in the flow direction by expanding the volume of the blank 8 by pushing out the blank 8 against the pressing force of the blank 8. A layer is formed. Therefore, as shown in FIG. 5, a three-layer structure in which some orientations of molecules (including the filler) of the skin layer 13 and the core layer 14 intersect with each other at an angle of 90 degrees.

Next, a remarkable effect of the present invention is demonstrated by using a molded article of a liquid crystal polymer containing 30% of glass fiber as an example. Product dimensions are 70mm width, 100mm length, 1 thickness
mm, the height of the rising wall and 4 mm, was compared with the case of not the case where the resin of the core layer to flow into the injection filling direction and the orthogonal direction immediately after injection filling. If not flow, flexural strength, injection filling direction 3200kgf / cm ^2, the cross direction is 1500 kgf / cm ^2. If allowed to flow thereto, injection filling direction 3000 kgf / cm ² and a slight decrease was observed in the cross direction was confirmed to be remarkably improved and 2600kgf / cm ^2. Also, in a 50% breaking energy test by falling weight impact, in the case of a punch diameter of 13.5 mm, the conventional example was 0.1 mm.
High strength such as 0.83 joules or more was confirmed against 46 joules. Furthermore, the magnitude of warpage due to deformation is
A significant decrease of 0.7 mm was found compared to the conventional 2.2 mm.

The above values are test results of a liquid crystal polymer molded article mixed with 30% of glass fiber, and the effect of the crystalline thermoplastic resin is remarkable, and it has been confirmed that the present invention is suitable. The thermoplastic resin used in the above is not limited to the liquid crystal polymer, and the same effect has been confirmed in these thermoplastic resins including a filler material. Although the present embodiment describes a thin plate-shaped molded product, the present invention can also be applied to a block-shaped, tubular, rod-shaped, or other complicated-shaped one. Furthermore, in order to promote the flow of the purpose, a vibration function of giving a vibration of 10 Hz or less is added to the piston rod which controls the pushing operation and the pushing operation of the block body, or the resin is moved in a direction crossing the injection filling direction. The means for causing the fluid to flow is not limited to the embodiment, for example, it is performed by a retracting operation of a piston rod.

The embodiment has a three-layer structure in which the orientations of the layers whose orientations intersect with the skin layer intersect at an angle of 90 degrees. The orientation with the skin layer intersects at an angle of 90 degrees. In addition, the orientations may intersect at an angle of, for example, 45 degrees. In the case of a thick molded product, the resin may flow in a direction intersecting the injection filling direction, and then the resin may further flow in a direction intersecting the direction to form a five-layer structure.

[0012]

According to the present invention, it is possible to provide a synthetic resin molded article having high accuracy and uniform strength in different directions.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an injection mold according to the present invention.

FIG. 2 is an explanatory view showing steps of an injection molding method according to the present invention.

FIG. 3 is an explanatory view showing steps of an injection molding method according to the present invention.

FIG. 4 is an explanatory view showing steps of an injection molding method according to the present invention.

FIG. 5 is an explanatory view showing the structure of an injection molded product according to the present invention.

[Explanation of symbols]

1. mold, 2. cavity, 3. gate, 4.5
..Reservoir pool, 6, Blank, 7, Block, 8,
・ Blank, 9 ・ Spring, 10 ・ ・ Block,
11 ... push rod, 12 ... piston rod, 1
3 ・ ・ Skin layer, 14 ・ ・ Core layer.

Claims (3)

(57) [Claims] 1. In injection molding a thermoplastic resin,
After the injection and filling of the molten resin into the cavity, while the core layer is not solidified , the core layer is caused to flow in a direction intersecting the injection and filling direction of the resin, and the core layer is oriented in the direction. Characteristic injection molding method. 2. A resin filling gate is provided on one side edge of the cavity, and an openable and closable resin reservoir communicated with the cavity is provided on one side of the gate that intersects the injection filling direction.
Injection molding dies each having a variable-volume resin reservoir connected to the cavity on the other side. 3. In injection molding of a thermoplastic resin,
After injecting and filling the molten resin into the cavity, apply resin pressure from one side of the cavity to the other side in a direction that intersects with the injection and filling direction to cause the unsolidified core layer to flow in that direction and cross the orientation with the skin layer. Molded products with different layers.