JPH0429806A - Long fiber containing thermoplastic resin pellet and melting device therefor - Google Patents

Abstract

PURPOSE:To make it possible to inject a hollow cylindrical, thermoplastic resin pellet into a mold without cutting long fiber contained in the pellet by a method wherein reinforcing fibers having a length nearly equal to the entire length of the pellet are contained in the pellet in its axial direction. CONSTITUTION:A pellet 14 contains along the axis of its cylindrical body reinforcing fibers having a length nearly equal to the entire length of the pellet. A main body 1 rotates about its axis to cause the upper end of each plunger 4 to slide along the surface of an inclined plate 5, whereby the plungers 4 vertically move. When the plungers upwardly move, a feed port 3 is opened so that the hollow cylindrical resin pellet 14 is inserted thereinto. The pellet 14 is pushed into a melting hole 2 as the plunger downwardly move and forced into the gap between a bar heater 6 and a cylindrical heater 7, where the pellet is melted and fed into an injection chamber 10 from a resin passage 8 through a valve 9 so as to be injected into a mold by a plunger 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to long fiber-containing thermoplastic resin pellets and an apparatus for melting the same.

[Prior Art] Injection molding is widely used because it is the most common thermoplastic resin molding method that allows molded products with relatively complex shapes to be produced quickly and with a high degree of freedom. Furthermore, in order to increase the strength of molded products, a method of mixing fibers into resin has been conventionally used.

In this case, the longer the length of the fibers, the higher the strength, but long fiber reinforced materials are often used in the form of shaped materials such as stampable sheets, and resin pellets for commonly used injection molding machines. The fiber length is restricted in this form, so it is not often used.

[Problems to be Solved by the Invention] In an in-line injection molding machine, a pellet-like free-form antiplastic resin material is introduced from a hopper, melted and kneaded by a screw, and then injected into a mold to form a molded product. Manufactured. In order to increase the strength of a molded product, when reinforcing fibers are blended into resin to form pellets and molded using the injection molding machine, the fibers are sheared by the rotating screw, making it difficult to obtain the desired strength. is difficult. For example, the fiber length contained in the resin pellet is about 10 mm at most, but the fiber length obtained after melting is about 5 mm, and the degree of resin reinforcement is low. For this reason, an injection molding machine cannot be said to be a suitable machine as a means for molding using a resin material containing long fibers. Therefore, if a resin material containing long fibers is to be used, it can only be used in a limited form such as a regular shaped material.

The present invention focuses on the above-mentioned conventional problems, and provides a thermoplastic resin pellet containing long fibers that can be injected into a mold as is without cutting the long fibers blended with the resin, and an apparatus for melting the same. The purpose is to

[Means for Solving the Problem] In order to achieve the above object, the long fiber blended thermoplastic resin pellet according to the present invention is a hollow cylindrical thermoplastic resin pellet, and the entire length of the pellet is Alternatively, reinforcing fibers with a length of several tens of mm may be blended into a string-like thermoplastic resin and wound into a spherical shape. It may also be a ribbon-shaped thermoplastic resin that is wound spirally.

In addition, the hollow cylindrical resin pellet melting device described above has a main body that rotates at a constant speed and has a plurality of resin pellet melting holes, and a rod-shaped heater on the center line of each melting hole and a cylindrical heater surrounding the melting hole. Above these heaters, a resin pellet supply hole for supplying hollow cylindrical resin pellets from the outside of the main body to each melting hole, and a plunger for pushing the supplied resin pellets into the heater portion are provided, and a plunger is provided above each melting hole. The molten resin passage provided at the bottom of the molten resin passage was connected to the resin injection chamber via an on-off valve.

[Function] According to the above configuration, the thermoplastic resin pellet is molded into a hollow cylindrical shape, and reinforcing fibers having a length spanning the entire length of the pellet along the axial direction are blended. The length of reinforcing fibers can be increased. Such a device for melting resin pellets quickly and continuously melts the resin pellets by pushing the resin pellets into a resin pellet melting hole equipped with a rod-shaped heater and a cylindrical heater, and then injects the molten resin into a resin injection chamber. With this structure, the molten resin can be injected into the mold without shearing the reinforcing fibers, and a molded product having desired strength can be obtained.

In addition, string-shaped thermosetting resin blended with reinforcing fibers was wound into a spherical shape to form pellets, or ribbon-shaped thermoplastic resin blended with reinforcing fibers was wound spirally to form pellets, so the reinforcing fibers blended into the resin were made into pellets. can be made to any desired length.

[Example] Examples of the long fiber-containing thermoplastic resin pellet and its melting device according to the present invention will be described in detail below with reference to the drawings.

Figure 1 is a longitudinal sectional view of a melting device for long fiber-containing thermoplastic resin pellets molded into a hollow cylindrical shape, and Figure 2 is A--A in Figure 1.
It is an A sectional view. 1 and 2, a cylindrical main body 1 has a plurality of resin pellet melting holes (hereinafter referred to as melting holes) 2 bored in the axial direction at equal intervals on the circumference.
Resin pellet supply holes (hereinafter referred to as supply holes) 3 that communicate with each melting hole 2 are opened on the outer periphery. Each melt hole 2
A plunger 4 is inserted into the upper part of each of the body 1, and as the body 1 rotates, these plungers 4 are moved up and down by a swash plate 5 provided above.

A rod-shaped heater 6 is provided in the lower part of each melting hole 2, and a cylindrical heater 7 is provided on the outer periphery of the hole, and a molten resin passage 8 that goes from the lower end of the melting hole 2 to the center of the main body 1 passes through an on-off valve 9 to the main body. 1 communicates with a resin injection chamber 10 installed below.

Inside the resin injection chamber 10 is a plunger 1 that reciprocates within the same chamber.
1 is provided. A heat insulating seal 12 is provided above and below the cylindrical heater 7, and above the heat insulating seal 12, a melting hole 2 and a supply hole 3 are formed by a room temperature or slow preheating member 13.

FIG. 3 is a perspective view of a resin pellet 14 molded into a hollow cylinder according to claim (1), in which reinforcing fibers are blended along the axis of the cylinder and have a length extending substantially over the entire length of the pellet. The approximate dimensions of the resin pellet 14 are an outer diameter of 14 to 16
mm, inner diameter 8 to 10 mm, and length 25 to 30 mm.

The main body 1 rotates with its axis as a rotation axis, and the upper end of each plunger 4 slides on the swash plate 5, so that the plungers 4 move up and down. When the plunger 4 rises, the supply hole 3 opens and a hollow cylindrical resin pellet 14 is inserted.

The resin pellet 14 is pushed into the melting hole 2 by the plunger 4 descending, and is fitted into the gap between the rod-shaped heater 6 and the cylindrical heater 7. Here, the resin pellets 14 are melted, flow into the resin injection chamber 10 from the molten resin passage 8 through the on-off valve 9, and are injected into the mold by the plunger 11.

The resin pellets 14 are sequentially inserted one by one from each supply hole 3 as the main body 1 rotates, and are continuously and rapidly melted.

A method may be adopted in which the main body 1 is fixed and the resin pellets are inserted when the swash plate 5 rotates and the supply hole 3 opens. Further, as shown in FIG. 4, a thin-toothed screw 15 may be used in the resin injection chamber installed below the main body 1. Note that a heater can also be installed around the outer periphery of the resin injection chamber 10 if necessary.

The pellets made by winding the string-like resin into a spherical shape as described in claim (2) and the pellets made by winding the ribbon-like resin in a spiral shape according to claim (3) are both inline injection equipped with a thin-toothed screw. Melt and mold using a molding machine.

[Effects of the Invention] As explained above, according to the present invention, long reinforcing fibers are blended along the axial direction of a hollow cylindrical thermoplastic resin pellet, or a string-like or ribbon-like thermoplastic resin is blended with long reinforcing fibers. Since long reinforcing fibers are blended, longer reinforcing fibers can be used even in resin pellets used as free-form materials. In addition, the device for melting hollow cylindrical resin pellets pushes the resin pellets into a melting hole equipped with a rod-shaped heater and a cylindrical heater, melts them quickly and continuously, and injects the molten resin into a resin injection chamber. With this structure, the molten resin can be injected into the mold without shearing the reinforcing fibers, and a molded product having desired strength can be obtained.

By using an in-line injection molding machine equipped with a thin-tooth screw, string-like or ribbon-like resin pellets containing reinforcing fibers can be used to suppress shearing of the reinforcing fibers to a small range and produce high-strength molded products. .

Injection molding is the most common thermoplastic resin molding method that allows molded products with relatively complex shapes to be produced quickly and with a high degree of freedom, and the present invention can be easily applied to this injection molding. Because of the form of the resin material and the melting means that can be used, fiber-reinforced plastic molded products can be obtained more easily and at lower cost than before.

Furthermore, the present invention can be applied to resins containing not only one type of fiber but also various types of fibers.

Furthermore, the present invention can be used not only for injection molding but also for general moldability using free-form materials in which resin materials are handled in the form of pellets, such as injection compression molding and injection press molding.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a long fiber blended thermoplastic resin pellet melting device according to an embodiment, FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1, and FIG. 3 is a hollow cylindrical FIG. 4 is a perspective view of the resin pellet and a partial sectional view when a thin screw is used in the resin injection chamber installed below the melting device. 1...Body 2...Resin pellet melting hole 3...Resin pellet supply hole 4.11φ...Plunger 6...Rod-shaped heater 7. ...... Cylindrical heater 8 ...... Molten resin passage 9φφ/am, opening/closing valve 10 ... Resin injection chamber 14 ... Resin pellet patent applicant Komatsu Manufacturing Co., Ltd. Procedural amendment (method) % formula % Display of the case 1990 Patent Application No. 137704 2゜ Title of the invention Long fiber-containing thermoplastic resin pellet and its melting device 3゜ Person making the amendment Relationship with the case

Claims (4)

[Claims] (1) A thermoplastic resin pellet containing long fibers, which is a hollow cylindrical thermoplastic resin pellet, and is characterized in that it contains reinforcing fibers having a length along the axial direction that spans almost the entire length of the pellet. (2) A long fiber-containing thermoplastic resin pellet characterized by blending reinforcing fibers with a length of several tens of mm into a string-like thermoplastic resin, and winding the string-like resin into a spherical shape. (3) The long fiber-containing thermoplastic resin pellet according to claim (2), wherein the string-like thermoplastic resin is a ribbon-like thermoplastic resin, which is wound spirally. (4) A plurality of resin pellet melting holes 2 are provided in the main body 1 that rotates at a constant speed, and a rod-shaped heater 6 and a cylindrical heater 7 surrounding the melting hole 2 are provided on the center line of each melting hole 2, respectively.
Above the heaters 6 and 7, a resin pellet supply hole 3 for supplying hollow cylindrical resin pellets 14 from the outside of the main body 1 to each melting hole 2, and a plunger 4 for pushing the supplied resin pellets 14 into the heater portion. and each melting hole 2
Claim 1 characterized in that a molten resin passage (8) provided at the lower part of the resin injection chamber (10) is connected to a resin injection chamber (10) via an on-off valve (9).
) long fiber blended thermoplastic resin pellet melting device.