JPS6116828A - Screw type extruding apparatus for thermosetting resin - Google Patents

Abstract

PURPOSE:To make an extruded item obtainable continuously and stably with good productivity, by facilitating a curing reaction in a clearance formed between a cylinder section and smooth section at the forward end of a screw, and shaping a material to such a degree that enables it to hold the shape by itself after the extrusion. CONSTITUTION:A thermosetting resin material fed from a hopper 1 is heated and melted in a cylinder 2 by a heater 3, is moved helically from the forward end of the flight of a screw 4 to a smooth section 5 and is compressed and fused due to the gradually decreased clearance between the cylinder and the screw flight that causes friction to the material. Then the fused resin is shaped in the course of movement through the screw smooth section to such a degree that enables it to hold the shape by itself after the extrusion. In this case, a back pressure applying apparatus 6 attached to the forward end of the cylinder gives a suitable back pressure to the resin enough to compress and fuse it. Thus, a shaped continuous pipelike item 7 that has a thick wall can be obtained stably with good productivity.

Description

[Detailed description of the invention] Industrial applications: The present invention relates to a novel extrusion molding apparatus for thermosetting resin.

Conventional techniques and their problems: Compression molding, transfer molding, injection molding, and extrusion molding are known as methods for molding thermosetting resins.
Equipment suitable for each molding method is used.

Among these thermosetting resin molding methods, a plunger extrusion device is generally used as an extrusion molding device (for example, Japanese Patent Application Laid-Open No. 48-83155, Plastics Y, Vo.
t25, A3, P47), long extruded products with simple shapes such as round bars and pipes are produced.

However, in the plunger extrusion molding apparatus, the extrusion pressure in the mold section is high and the extrusion is performed intermittently, so it is difficult to obtain uniform molded products and the productivity is low.

Under these circumstances, a molding method using a so-called screw type extrusion molding apparatus has been disclosed, for example, in Japanese Patent Application Laid-Open No. 54-23661. This is a molding device that guides the cross-melted thermosetting resin in the extruder into the mold through an adapter and shapes it into the final shape.

However, in such a forming device, the resin flow path changes in a complicated manner, and the thermosetting reaction may proceed rapidly due to a slight difference in temperature or pressure, or the curing reaction may proceed locally due to the occurrence of stagnation. This made it difficult to perform continuous and stable molding.

Furthermore, with this type of device, it has not been possible to avoid quality problems caused by spider marks or welds caused by the presence of a part of the spider supporting the mandrel.

The present inventors have developed a method for molding thermosetting resin molded products with excellent flame retardancy, heat resistance, etc., which are in strong market demand in the fields of architecture, electricity, electronics, etc., and in particular, various methods for solving the above-mentioned problems. As a result of repeated studies, we discovered that the purpose could be achieved continuously, stably, and with good productivity by shaping the smooth part of the screw to the extent that it could retain its extruded and extruded shape. provided new equipment to (Patent application No. 58-51526, Patent application No. 104891-1983)
That is, the device consists of a screw consisting of a supply section, a compression section, a metering section and a smooth section, a cylinder section having a heat supply function corresponding to the supply section, compression section and metering section, and a final screw diameter of the metering section. It is composed of a cylinder part having a heat supply function corresponding to the smooth part having the same or different diameter, and promotes the curing reaction in the gap formed by the smooth part and the corresponding cylinder part, and has a self-shaping shape after extrusion. This is a screw-type extrusion molding device for thermosetting resin that can be shaped to the extent that it can hold.

However, according to the findings of the present inventors, when manufacturing thick-walled pipes using the above-mentioned apparatus, as the wall thickness increases, depending on the material, sufficient back pressure may not be obtained, and Problems such as insufficient compression and bonding of the resin resulted in easy cracking, and the surface smoothness was lost, resulting in poor gloss. These problems can be solved by changing the compression ratio and length of the smooth part of the screw, but in that case, it is necessary to prepare screws suitable for each depending on the wall thickness and material properties. There is.

Means for solving the problem: The inventors of the present invention have investigated various means that do not cause the above-mentioned problem when using screws with the same wall thickness even when the material properties are changed. The present invention was achieved by discovering that a pipe with good wall thickness can be obtained by attaching a back pressure applying device to the tip.

That is, the present invention provides a screw consisting of a supply section, a compression section, a metering section, and a smooth section, a cylinder section having a thermal control mechanism corresponding to the supply section, the compression section, and the metering section, and a screw having a diameter equal to the final screw diameter of the metering section. or a cylinder part having a heat supply function corresponding to the smooth part having a different diameter, and a pressure applying device attached to the tip of the cylinder, in the gap formed by the smooth part and the corresponding cylinder part. This is a screw-type extrusion molding device for thermosetting resin that accelerates the curing reaction and shapes the resin to the extent that it can maintain its own shape after extrusion.

The feature of the present invention is that when shaping thermosetting resin using a screw with a smooth portion at the tip, the back pressure during extrusion molding can be adjusted by attaching a back pressure applying device to the tip of the cylinder. be.

To explain the invention with the aid of figures, FIG. 1 shows one example of a preferred apparatus for carrying out the method of the invention.

In Fig. 1, the thermosetting resin material supplied from the hopper 1 is heated and melted by the heater 3 in the cylinder 2, moves from the tip of the flight of the screw 4 to the smooth part 5 in a spiral shape, and then joins the cylinder. Due to the frictional resistance, the gap created by the screw flight is narrowed and finally pressure fused.

Next, while the fusion resin moves on the screw smooth part,
After extrusion, the resin is shaped to the extent that it can maintain its own shape, and at this time, an appropriate back pressure is applied by the back pressure applying device 6 installed at the tip of the cylinder, and the resin is sufficiently pressure-fused and shaped to form the cylinder. The tip passes through a back pressure applying device and is extruded into a continuous pipe-shaped molded product 7.

Figures 2 and 3 show an example of a back pressure applying device which is one of the features of the present invention.
The split mold is tightened by screwing the tool into the adapter 10 and the adapter 10. By changing the degree of tightening, the effect of applying back pressure can be adjusted.

The back pressure applying device of the present invention is not limited to this structure, but for example, a structure in which a groove is cut at one end of the cylinder and tightened from the surroundings, or a structure in which the inner diameter of the cylinder is narrowed toward the tip. (In this case, the effect of applying back pressure is fixed) etc. For tightening, methods such as hydraulic pressure, pneumatic pressure, springs, etc. can be used in addition to screwing. . In other words, the back pressure applying device referred to in the present invention may be any device that has an inner diameter that is extremely slightly smaller than the inner diameter of the cylinder, and the
It is sufficient as long as it provides a suitable amount of resistance when the pipe passes through. Further, it would be even more desirable if the mechanism could adjust its inner diameter.

Another feature of the extrusion molding apparatus of the present invention is that the tip of the extruder is shaped using a reed, particularly a screw having a smooth portion at the tip. The extrusion equipment used is
Not only a single-screw extrusion device, but also any extrusion device, such as a twin-screw extrusion device or a multi-screw extrusion device, whose tip end is finally consolidated into a single screw can be used. The internal structure of these extrusion devices that can be used in the present invention is as follows:
There is no problem in providing a deaeration hole or a special cross-wire structure between the supply section and the measuring section at the tip of the extrusion device.

A typical screw used in the present invention is a fourth screw.
As shown in the figure, it is a screw (hereinafter referred to as a special screw) having a smooth portion 5 at its tip, and this screw includes, for example, a supply section 11, a compression section 12, and a metering section 13. The smooth section 5 may be of a type such that it starts from the end of the supply section as shown in Fig. 4, from the end of the compression section as shown in Fig. 5, or from the middle of the measuring section as shown in Fig. 6. .

In addition, the diameter of the screw in the smooth part 5 or the inner diameter of the cylinder in that part may be equal to or different from the diameter of the screw bottom of the part having flights and/or the inner diameter of the cylinder, depending on the outer diameter and inner diameter of the desired molded product. The diameter can be adjusted by expanding or contracting.

The L/D of the special screw used in this device is:
Usually 7-40, preferably 10-35, more preferably 15-25, compression ratio 1.0-5.0 preferably 1.2
~40, more preferably 15~6.01 The length of the smooth part of the tip of the screw is 1D~15D, preferably 2D~10
D1, more preferably, can be appropriately selected from the range of 2D to 7D.

A normal full-flight screw without a smooth part at the tip cannot produce a pipe-shaped molded product, but only a helical-shaped molded product. Furthermore, if the length of the smooth portion is less than 1D, the molded product obtained after extrusion will be deformed, making it difficult to continuously obtain a good molded product. Also, the length of the smooth part is 15
When it is D or more, the molding pressure becomes large and it is not practical from the point of view of the mechanical strength of the extrusion device.

The compression ratio of the screw and the length of the smooth part are determined by the gap formed by the smooth part of the screw and the corresponding cylinder part, in other words, by a combination of the thickness of the molded product, extrusion speed, and the characteristics of the material used. Subject to various restrictions. The larger or smaller the compression ratio of the screw and the length of the smooth portion, the larger or smaller the back pressure applying function.

If the back pressure is too large, excessive cross-talk will occur in the portion having flights, resulting in excessive heat generation and hardening of the material, which is undesirable. On the other hand, if the back pressure is too small, compression and filling of the material and crosstalk will become insufficient, which is likewise undesirable. Adequate back pressure is necessary for compaction filling of the material and adequate cross-crossing.

That is, in order to achieve stable extrusion and a good product, an appropriate compression ratio of the screw and a suitable length of the smooth portion are required.

The larger or smaller the gap formed by the smooth part of the screw and the corresponding cylinder part, the lower or higher the extrusion speed, the lower or higher the viscosity of the material used, the more The lower or higher the curing rate, the larger or smaller the compression ratio of the screw and the length of the smooth part need to be.

When using this screw type extrusion molding equipment,
The temperature settings for each part of the extrusion device will naturally vary depending on the combination of the characteristics of the material used, the compression ratio of the screw, the gap between the smooth part of the screw and the barrel, the length of the smooth part, the extrusion speed, etc.
The temperature setting of the cylinder parts corresponding to the compression part, metering part, and smooth part of the screw is usually in the range of 50 to 200 °C, preferably 60 to 150 °C, and the heat supply function of the heat capacity that can normally be molded at this set temperature is A cylindrical structure is adopted.

However, if the set temperature is below 50°C, the curing reaction of the resin will not proceed sufficiently and it will be difficult to obtain a good molded product.On the other hand, thermosetting resins normally used at temperatures up to 200°C will Since it is thermally cured, there is no need for any further heat supply function.

In this screw type extrusion molding apparatus, the curing reaction is promoted in the gap formed by the screw smooth part and the corresponding cylinder part, and the curing reaction is advanced to at least the extent that the molded product can maintain its own shape after extrusion, and during this time The finished product is then shaped into the final molded product or a shape that closely approximates it.

In conventional extrusion molding of thermosetting resin, the resin is heated and melted in a cylinder, then introduced into the mold through an adapter and shaped into the final shape, but during this process, the flow of the resin is Because the flow path of the resin changes in a complicated way, such as being squeezed with an adapter and re-expanded into a mandrel fixed with a spider, resin tends to stagnate, and the curing reaction progresses locally. Changes in pressure or temperature can cause problems such as rapid curing reactions. -! However, in order to overcome the resistance created by the complicated flow paths and extrude the resin while preventing stagnation, it requires enormous extrusion pressure and special extrusion equipment. However, when using such a molding method, the extrusion speed is at most about 3 QcWL/min, and it is difficult to obtain a product with good roundness and wall thickness distribution.

According to the screw type extrusion molding apparatus of the present invention, the gap formed by the screw smooth part and the corresponding cylinder part plays the role of a mold, and the only resin flow path is the gap between the cylinder and the screw. There is no stagnation of resin at all, and localized curing reactions and rapid curing reactions due to changes in pressure and temperature do not occur.

In addition, the screw of the present invention has an open tip and has a pressure increasing function part and a back pressure applying function part over its entire length, so the forces of the two cancel each other out and the force applied to the thrust bearing of the screw is reduced by the force between the screw and the mold. It is inherently smaller than the common extrusion methods used.

Furthermore, since the smooth part of the screw of the present invention, which corresponds to the mandrel in the mold in general extrusion molding, is rotating, the frictional resistance between the hardened resin and the metal part is relatively small, and the extrusion pressure is also low. Pressures obtained with conventional screw extrusion equipment are sufficient. With this type of apparatus of the present invention, an extrusion speed of 80 m/min can be easily obtained.

Thermosetting resins used in the present invention include phenolic resins, melamine resins, urea resins, unsaturated polyester resins, epoxy resins, silicon resins, allyl resins, xylene resins, aniline resins, etc. Among them, phenolic resins It is also suitable for molding melamine resin.

Therefore, these thermosetting resins may contain fillers, mold release agents, thickeners, colorants, dispersants, blowing agents, or other agents commonly used in the molding of thermosetting resins, as necessary. A polymerization initiator, a curing accelerator, a polymerization inhibitor, etc. can be added. Furthermore, other types of polymers or organic or inorganic fibrous materials such as glass can also be added.

The thermosetting resin pipe obtained by the above-mentioned screw type extrusion molding apparatus of the present invention has excellent heat resistance, flame resistance, chemical resistance, and pressure resistance, and is suitable for various piping materials, such as fluid transfer pipes and protection pipes. This is useful.

Effect: By using the device of the present invention, the back pressure inside the cylinder can be optimally maintained, and the resin can be sufficiently compressed and fused in the smooth part, making it possible to obtain thick-walled pipes stably and with high productivity. In addition, a pipe with excellent gloss and surface smoothness and good straightness can be obtained, and the strength of the pipe is also improved.

The present invention will be further explained below with reference to Examples.

Example 1 A water cooling jacket was provided at a length of 2D from below the hopper, and the back pressure applying device shown in FIG. 3D, the compression part 14D1 has a length of 4D and a diameter of 32mm at the tip that continues to the measuring part with a diameter of 32mm at the bottom of the screw. ．． A screw with a smooth part is used, and phenol resin (manufactured by Nippon Gosei Kako Co., Ltd., product name Nikkarai) is used as the molding material.
950-J) was used for molding.

The temperature of each part of the cylinder is C□ (0~2D)...Water-cooled C2 (3D~10D)...80℃C3 ('11D)
~16D)...95℃C4(17D~20D)・
...115℃C5 (21D~24D)...125
℃, the inner diameter of the split mold of the back pressure applying device was reduced to 6 mm, and extrusion was performed at a screw rotation speed of 35 rpm.

The results are shown in Table 1.

Comparative Example 1 Using the same extruder, screw, and molding material as in Example N1, extrusion molding was performed under the same conditions without adding a back pressure applying device.

The results are shown in Table 1.

Example 2 Using the same equipment as in Example 1, molding was performed using phenol resin (trade name: 0N-4400, manufactured by Matsushita Electric Works, Ltd.) as a molding material.

The temperature of each part of the cylinder is C□...water cooling, C2...
...80℃, C3...100℃, C4...12
The temperature was set at 0°C, C5...130°C, the inner diameter of the split mold of the back pressure applying device was set to 39.8 mm, and extrusion was performed at a screw rotation speed of 35 rpm.

The results are shown in Table 1.

Comparative Example 2 Extrusion molding was carried out using the same extruder, screw, and molding material as in Example 2 under the same conditions without using a back pressure applying device. The results are shown in Table 1.

Example 3 Using the same equipment as in Example 1, molding was performed using melamine resin (trade name: 0N-600, manufactured by Otalite Co., Ltd.) as a molding material.

The temperature of each part of the cylinder is C□...water cooling, C2...
...85℃, C3...105℃, C4...12
Set the temperature to 5℃, C5...140℃, reduce the inner diameter of the split mold of the back pressure applying device to 697mm, and set the screw rotation speed to 32mm.
Table 1 shows the results for extrusion at rpm.

Comparative Example 6 Using the same extruder, screw, and molding material as in Example 3, extrusion molding was carried out under the same conditions without adding a back pressure applying device. The results are shown in Table 1.

[Brief explanation of drawings]

FIG. 1 shows an example of a screw having a smooth portion, and FIG.
FIGS. 7 to 12 are charts showing the surface smoothness of the pipes obtained in each Example and each Comparative Example. 1...Hopper 2...Cylinder 3...
・Heater 4...Screw 5...Smooth part 6...Back pressure applying device 7...Molded product 8...
- Split mold 9... Tightening tool 10... Adapter 11... Supply section 12... Compression section 13.
...Measuring part

Claims (1)

[Claims] 1) A screw consisting of a feeding section, a compression section, a metering section and a smooth section, a cylinder section having a thermal control mechanism corresponding to the feeding section, compression section and metering section, and a diameter equal to or different from the final screw diameter of the metering section. and a back pressure applying device attached to the tip of the cylinder, and in the gap formed by the smooth part and the corresponding cylinder part. A screw type extrusion molding device for thermosetting resin that accelerates the curing reaction and shapes the resin to the extent that it can maintain its own shape after extrusion.