JPS634920A - Molding of fiber reinforced plastic - Google Patents

Abstract

PURPOSE:To prevent entanglement of fibrous fillers to unify the dispersement thereof and obtain a molded form without scattering in the strength thereof, by a method wherein a molding material is mixed with specified fibrous fillers and is heated and conveyed by employing a screw having a specified L/D and taper of a shaft. CONSTITUTION:Molding material 2 is mixed with fibrous filler of the length of 5-50 mm under a condition that a plurality of the fibers are bundled while interposing synthetic resin powder 7 between the fillers 1, and the bundle is covered by a synthetic resin film 6 of the same quality as the powder 7, further as a heat conveying mechanism 3, a screw is used wherein L/D is at least 25 and a taper of a shaft 10 is at most 0.02, and the molding of the material is effected by an injection-compression- development method. The length of the fibrous filler is 5-50 mm, therefore, a molded form may be imparted with a sufficient strength and, further, as a heat conveying mechanism the screw having L/D of 25 or more and the shaft taper of 0.02 or less is employed, therefore, such a molded form can be obtained in which the entanglement of the fibrous filler, accompanied by the pressure kneading of the molding material, is eliminated, the dispersion of the fibrouas filler is uniform and scattering in the strength thereof is eliminated.

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a method for molding fiber-reinforced plastics, and its purpose is to provide a molded product with uniform strength, precision, and excellent strength, and to provide a smooth molded product without congestion. The goal is to realize molding operations that are as easy as possible.

(Prior art and its problems) Conventionally, fiber-reinforced plastics have been molded using a molding material (b) containing a fibrous filler (al), as shown in Figure 3.
) is compressed and kneaded using an injection molding machine (C1), and the kneaded product is supplied into the cavity +el of the mold (d) and molded.

However, in such conventional methods, the fibrous filler (a) is
Add a fixed amount of synthetic resin (fl) to the molding material (bl) in a state of solidification into pellets, and use a screw with an L/D of 20 or less and a shaft taper exceeding 0.02 as the injection molding machine (C). As a result, there were the following problems:

That is, the fibrous filler (a) that can be mixed into the pellets
Since the length of the pellet is approximately 0.3 to 0.4 mm, sufficient strength cannot be imparted to the molded product, and the fibrous filler (a) in the pellet is dispersed in no direction.
During compression kneading, these particles became entangled with each other, resulting in non-uniform dispersion and uneven strength of individual molded products.

In addition, since the injection molding machine (C1 uses a screw with an L/D of 20 or less and a shaft taper of more than 0.02), the material becomes pressurized and cross-wired, cutting the fibrous filler fat and further increasing the fiber length. is short (original 115~1
/10), which may further weaken the strength of the molded product, and the pressure kneading may cause the fibrous filler (a)
As the dispersion state of the resin deteriorated, the strength of the molded product became non-uniform.

In addition, since the molding is performed by injection molding, the injection of the molten material into the mold (d) must be performed by high-pressure injection through the small diameter nozzle (g), and the small diameter nozzle (g) is used to fill the fibrous material. There was a fear that the molding work would be frequently interrupted due to clogging with the material (a).

(Means for Solving the Problem) In this invention, the fibrous filler has a length of 5 to 50n+.
In addition, this fibrous filler is bundled with synthetic resin powder interposed between them, coated with a synthetic resin film of the same quality as the powder, mixed into the molding material, and heated and transported. All of the above problems are solved by using a screw with an L/D of 25 or more and a shaft taper of 0.02 or less, and by performing molding by the injection pressure expansion method.

(Example) Embodiments of the invention will be described based on the drawings.

FIG. 1 is a diagram illustrating a molding apparatus according to a molding method according to an embodiment of the present invention.

In order to mold fiber-reinforced plastic using the molding apparatus according to the embodiment of the present invention, a molding material 1l-I (21) mixed with a fibrous filler (], ) is melted and transported by a heating transporting machine (3). This molten material is transferred to the cavity of the mold (4) (
5) Molding is performed by supplying the material inside the container.

The fibrous filler (1) has a length of 5 to 50 mm. If it is shorter than this, sufficient strength cannot be imparted to the molded product, while if it is longer than this, the resistance during transportation will be large.
This is because only the fibrous filler (11) stagnates in the heating 1 general feeder (3) and the dispersion state becomes non-uniform. Note that within this range, 20 to 30 mm is most effective.

Moreover, the thickness used is 7 to 30 μm in diameter. ′
If it is thinner than this, sufficient strength cannot be imparted to the molded product, while if it is thicker than this, when it is made into a bundle, as will be described later, the thickness of the bundle will be thicker and the resistance during transportation during heated transportation fi 131 will be large. Therefore, only the fibrous filler (1) is transferred to the heating conveyor (3).
) and the dispersion state becomes uneven. It should be noted that within this range, 25 to 35μ is most effective.

The materials used include fibrous fillers, glass fibers, and various other fibers effective for reinforcing plastics.

Furthermore, the blending amount is 10 to 50% by weight.

This is because if the amount is less than this, sufficient strength cannot be imparted to the molded product, and on the other hand, if it is more than this, the resistance during conveyance in the heating conveyor (3) increases as described above.

Note that within this range, 25 to 35% by weight is most effective.

As the material for the molding material (2), both thermoplastic resins such as ABS and thermosetting resins such as unsaturated polyester resins are used.

In order to mix the fibrous filler (1) into the molding material (2), a plurality of fibrous fillers (1) are bundled with synthetic resin powder (7) interposed between them, and a synthetic resin coating ( 6) is mixed into the molding material (2). Synthetic resin powder (7
) was used to maintain the spacing between the fibrous fillers (1) to ensure a dispersed state in advance, and to give flexibility to the bundle so that it could be cut by bending during transportation. This is to prevent The reason why the synthetic resin film (6) was used is to maintain the above-mentioned dispersed state until near the end of conveyance and to improve the dispersion of the fibrous filler (1) in the molded product.

The amount to be bundled is 100 to 3,000.

If the blending amount is less than this, the number of bundles will inevitably increase, and the fibrous filler dispersed in the heating conveyor (3) +11
This is because there is a large variation in the directionality of the bundle, and the dispersibility deteriorates due to mutual entanglement.On the other hand, if the number is larger than this, the bundle becomes thick, the conveyance resistance increases, and sufficient dispersion cannot be achieved.

Moreover, the diameter of this bundle is suitably 0.2 to 8 mm.

Further, as materials for the synthetic resin powder (7) and the synthetic resin coating (6) in this case, any of various thermoplastic resins or thermosetting resins can be suitably used.

As a heating conveyor (3), L/D is 25 or more and shaft α
0) Use a screw with a taper of 0.02 or less.

The taper of the shaft aω is 0.0 when the conventional L/D is 20 or less.
This is because if the number of screws exceeds 2, the material to be conveyed will be in a pressurized cross-wire state, which will reduce the strength of the molded product due to cutting of the fibrous filler +11, and at the same time, the dispersibility will be inhibited by the entanglement of the fibrous filler +11.

The injection pressure expansion method was used for molding. As shown in Fig. 1, the injection pressure spreading method involves injecting molten material into an open mold (4) with a shear edge, and closing the mold in an interlocking manner to inject the molten material into the mold (4). The inner diameter of the injection nozzle (8) can be made into at least 6 fins by the method of spreading and shaping. In injection molding, the inner diameter of the injection nozzle must be made very small because it is necessary to perform high-pressure injection into the mold, and the fibrous filler + 1
There is a risk of congestion in the molding work due to clogging in step 1, and in compression molding, the molding material must be weighed and added in solid form (sheet form, etc.), which reduces productivity due to the complexity of the charging process. be.

In addition, in injection compression molding, molten material is injected into a slightly open parting line type mold, and then the mold is closed and the molten material is forced into the mold to form the mold. This is because it can only be used for specific purposes and lacks versatility.

Incidentally, during the compounding, additives effective for ordinary plastic molding, such as plasticizers and stabilizers, are of course added in arbitrary amounts. Note that (9) in the figure is an accumulator for feeding the measured amount of molten material into the mold.

In addition, FIG. 2 shows an example of a modification of the molding apparatus related to the molding method of the embodiment of the present invention, and in this example, the heating conveyor (3)
Injection is used as

(Effects) As explained above, in this invention, a fibrous filler with a length of 5 to 50 mm is used, and moreover, a plurality of fibrous fillers are bundled and synthesized with synthetic resin powder interposed between them. It is mixed into the molding material in a state covered with a resin film, a screw with an L/D of 25 or more and a shaft taper of 0.02 or less is used as a heating conveyor, and the molding is performed by the injection pressure expansion method, so the following effects are achieved. play.

That is, the length of the fibrous filler is 5 to 50IllI1.
1, sufficient strength can be imparted to the molded product.

In addition, since the fibrous filler is mixed into the molding material in the form of a bundle with synthetic resin powder interposed between them, the fibrous filler can be transported and molded with the fibrous filler dispersed in advance. Mutual entanglement can be prevented, dispersion can be made uniform, and molded products with uniform strength can be provided. In addition, since the bundle of fibrous filler is coated with a synthetic resin film, the above-mentioned dispersion of the fibrous filler can be maintained until the middle of transportation, and the dispersion state of the fibrous filler in the molded product can be made uniform, ensuring uniform strength. We can provide molded products.

In addition, since a screw with an L/D of 25 or more and a shaft taper of 0.02 or less is used as the heating conveyor, there is no tangle of fibrous filler accompanying pressurization of the molding material.
The fibrous filler is uniformly dispersed, which is further advantageous in providing molded products with uniform strength.

Furthermore, since the molding is performed by the injection pressure expansion method, there is no need to use a small-diameter injection nozzle as in conventional injection molding (there is no clogging of the injection nozzle, and there is no congestion during the molding operation.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a molding apparatus according to a molding method according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of a modified side of the same molding apparatus, and FIG. 3 is an explanatory diagram of a molding apparatus according to a conventional molding method. . (Former... fibrous filler (2)... molding material (3)
... Heating conveyor (4) ... Mold (5) ...
Cavity (6)...Synthetic resin coating (7)...
・Synthetic resin powder

Claims (1)

[Claims] (1) In a method for molding fiber-reinforced plastics, in which a molding material mixed with a fibrous filler is melted and transported by a heated transporter, and the molten material is fed into a cavity of a mold for molding, the fibrous filler is A filler with a length of 5 to 50 mm is used, and a plurality of fibrous fillers are bundled with synthetic resin powder interposed between them and covered with a synthetic resin film of the same quality as the powder, and then added to the molding material. and the shaft taper is 0 when L/D is 25 or more as the heating conveyor.
．． A method for molding fiber-reinforced plastics, characterized in that a screw of 0.02 or less is used and the molding is performed by a jet pressure expansion method.