JPS6155150A - Thermosetting resin molding material - Google Patents

Abstract

PURPOSE:To provide the titled molding material which has excellent flame retardance and heat resistance, can be shaped to such an extent that its shape can be self-retained after extrusion, and gives moldings having an excellent appearance continuously and stably, consisting of a thermosetting resin and a polymer having a specified second-order transition temp. CONSTITUTION:100pts.wt. thermosetting resin such as phenolic resin or curable resin obtd. by crosslinking a thermoplastic resin such as PVC, 1-100pts.wt. polymer (e.g. styrene/butadiene copolymer) having a number-average MW of 500- 300,000 and a second-order transition temp. of 50 deg.C or below, and optionally filler, reinforcing agent, etc. are kneaded together to obtain the titled molding material. The material is fed to an extruder having a screw which is composed of a feed zone 1, a compression zone 2 and a metering zone 3 in which a smooth zone 4 is formed from the end of the feed zone 1 or the compression zone 2, and which has an adjusted diameter enlarged or reduced according to the outer and inner diameters of the desired molding in an L/D ratio of 7-20. The material is extruded at 50-200 deg.C and shaped during the passing thereof through the smooth zone 4 to such an extent that its shape can be self-retained, thus obtaining the desired molding.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a novel extrusion molding method for thermosetting resins with excellent flame retardancy and heat resistance, which are in strong market demand in the fields of architecture, electricity, electronics, etc. Regarding materials.

[Conventional technology]

Compression molding, transfer molding, injection molding, and extrusion molding are known as methods for molding thermosetting resins, such as phenolic resins, and molding materials suitable for each molding method are used.

Among these methods for molding phenolic resins, two extrusion methods have been developed: a plunger extrusion method and a scrier extrusion method.

[Problem that the invention seeks to solve]

Plunger extrusion is used to produce long extruded products with simple shapes such as round bars and pipes. However, in the plunger extrusion molding apparatus, the extrusion pressure in the mold section is high, and furthermore, because of intermittent extrusion, it is difficult to obtain uniform molded products and the productivity is low.

Under these circumstances, a molding method using a so-called screw extrusion molding device has been developed. This is a molding device that introduces a phenolic resin molding material that has been mixed and melted in an extruder into a mold through an adapter 7 and shapes it into a final shape. However, with conventional phenolic resin molding materials, the extrusion pressure in the mold part is high (and intermittent extrusion is used, so a uniform molded product cannot be produced.In addition, in such molding equipment, the flow path of the molding material is complicated. The curing reaction of the phenolic resin rapidly progresses due to slight differences in temperature or pressure, or the curing reaction progresses locally due to the occurrence of stagnation, and phenolic resin materials that can be stably molded over a long period of time have not been found. It has not been.

The present inventors have previously provided a new molding method that solves the problems of the conventional extrusion molding method. (Patent application 1984-10489
1) The molding method employs, for example, a thermosetting resin extrusion molding method in which a screw having a smooth portion at the tip is used and the smooth portion is shaped to the extent that it can maintain its own shape after extrusion. However, even in this case, conventional phenolic resin materials have poor moldability and are difficult to continuously and stably mold.

[Failure to solve the problem]

The present inventors conducted various studies to solve the above-mentioned problems with thermosetting resin materials, and as a result, the thermosetting resin molding material has a secondary transition temperature (hereinafter abbreviated as Tv point) of 50°C or less. The present invention was achieved by discovering that by blending a specific amount of a polymer, it is possible to shape the material to the extent that it can maintain its own shape χ, and also to enable continuous and stable molding.

That is, the present invention uses a screw having a smooth portion at the tip and shapes the screw to such a degree that it can maintain its own shape after extrusion in the smooth portion, or has an inner diameter approximately equal to the inner diameter of the cylinder of the extruder. A die having a die inlet formed by a cylindrical part having an outer diameter equal to g is attached to the bottom outer diameter of the cylindrical part and the screw tip in close proximity to the screw tip. It is a molding material that is shaped to the extent that it can be held, and is a thermosetting resin.
This is a thermosetting resin molding material suitable for continuous extrusion molding, which contains 1 part by weight or more and less than 100 parts by weight of a polymer having a secondary transition temperature of 50° C. or lower per 00 parts by weight.

Thermosetting resins used in the present invention include thermosetting resins such as phenol resin, melamine resin, urea resin, unsaturated polyester resin, epoxy resin, silicone resin, allyl resin, xylene resin, and aniline resin, and polyethylene, Examples include curable resins made of thermoplastic resins such as polypropylene, polystyrene, and polyvinyl chloride using a crosslinking agent.

Examples of the 12-point 50°C or lower polymer used in the present invention include styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, isobutylene copolymer, chloroprene copolymer, isoprene copolymer, Ethylene-propylene copolymer, silicone copolymer, 7
Examples include nitrogen-based polymers, urethane-based polymers, acrylic copolymers, etc., and usually have a number average molecular weight of 500 or more and 300,
000. Further, the above polymer may contain reactive groups such as epoxy groups, hydroxyl groups, amine groups, and carboxyl groups as functional groups within the seven molecules.

In addition, when using a polymer having a T point of 50° C. or higher, it is difficult to achieve continuous and stable molding, which is a feature of the present invention.

The above-mentioned combination used in the thermosetting resin molding material is used in an amount of 1 part by weight or more and less than 100 parts by weight, preferably 5 parts by weight or more and 20 parts by weight, based on 100 parts by weight of the thermosetting resin.

If the amount used is less than 1 part by weight, there is almost no effect of improving extrusion moldability, and stable molding is difficult, and phenomena such as hardening and clogging often occur in the extruder. 10 more
If the amount is 0 part by weight or more, the extrusion moldability will be good, but the molded product will swell or deform during extrusion molding, making it difficult to obtain a satisfactory molded product.

The above polymers are made into a thermosetting 4itt resin composition by conventional mixing and cross-mixing methods. In this case, commonly known fillers such as calcium carbonate, clay, talc, silica, aluminum oxide, antimony trioxide and reinforcing materials,
glass fiber, asbeth) [inorganic fibers such as fibers, wood powder,
Pulp or synthetic fibers such as vinylon, nylon, and pigments.

Other auxiliary rings may be used in combination. These mixed compositions may be further kneaded using rolls or the like at a temperature of 50 to 170°C, and then used in the form of pellets or powder.

The thermosetting resin molding material of the present invention is suitable as a molding material for the following continuous extrusion molding method for thermosetting resins.

The first shaping method is characterized by the structure of the tip of the extruder, particularly in that shaping is performed using a screw having a smooth portion at the tip. As the extruder to be used, not only a single screw extruder but also a twin screw extruder or a multi-screw extruder in which the tip end is finally consolidated into a single screw extruder can be used. As for the internal structure of these extruders that can be used, 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 extruder.

A typical screw is a screw (hereinafter abbreviated as a special screw) having a smooth portion 4 at the tip end as shown in FIG. It consists of a measuring section 3. The smooth part 4 is the first
It may be of a type that starts from the end of the supply section as shown in the figure, from the end of the compression section as shown in FIG. 2, or from the middle of the metering section as shown in FIG.

In addition, the diameter of the screw in the smooth part 4 or the inner diameter of the cylinder in that part can be expanded or reduced in accordance with the outer diameter and inner diameter of the desired molded product, independently of the diameter of the screw bottom or the inner diameter of the cylinder in the part with flyton. can be adjusted.

The L/D of the special screw is usually 7 to 40, preferably 10. -35, more preferably 15-25, compression ratio is 1
．． 0 to 5.0, preferably 1.2 to 4.0, more preferably 1.5 to 380, the length of the smooth part of the screw tip is 1D to 15D, preferably 2D to 10D, more preferably 2D to 7D. It can be selected as appropriate from the range. Therefore, if the length of the sliding part at the tip of the screw is less than 1D,
Deformation occurs in the molded product obtained after extrusion, making it difficult to consistently produce good molded products. Also, the length of the smooth part is 15D
If the pressure is higher than that, the molding pressure becomes high and it is not practical from the viewpoint of mechanical strength of the extruder.

The compression ratio of the screw and the length of the smooth part are subject to various restrictions depending on the gap between the screw and the barrel in the smooth part, in other words, the thickness of the molded product, the extrusion speed, the characteristics of the material used, etc. Therefore, the larger or smaller the compression ratio of the screw and the length of the smooth portion, the better (or smaller) the back pressure applying function becomes.

This is undesirable because excessive crosstalk occurs in areas where the back pressure is high and there are gaps and flights, resulting in excessive heat generation and hardening of the material. 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 and proper kneading of the material.

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 narrower or smaller the gap between the smooth part IJ and the barrel, the lower or higher the extrusion speed, the lower or higher the viscosity of the material used, the more
Furthermore, the slower or faster the curing speed of the material used, the larger (or smaller) the compression ratio and length of the smooth part of the screw need to be.

The temperature settings for each part of the extruder will naturally vary depending on the combination of the characteristics of the material used, the compression ratio of the screw, the gap between the screw smooth part and the barrel, the length of the smooth part, the extrusion speed, etc. The temperature setting of one part of the cylinder corresponding to the smooth part is usually 50 to 200°C, preferably 6°C.
It is in the range of 0 to 150°C. Therefore, the set temperature is 50℃
In the following cases, it is difficult to obtain a good molded product because the curing reaction of the resin does not proceed sufficiently.On the other hand, thermosetting resins that are normally used at temperatures up to 200°C are sufficiently thermoset, so the temperature should be higher than that. There's no need.

This will be explained below using figures. 1 to 6 are side views showing an example of a screw having a smooth portion at its tip.

FIG. 4 shows one example of a preferred extrusion device and includes a perspective view of a portion of the screw.

In the figure, the thermosetting resin material supplied from the hopper 5 is heated and melted by the heater 7 in the cylinder 6, moves from the tip of the screen 8 to the smooth part 4 in a helical shape, and connects with the cylinder. Due to the frictional resistance, the gap created by the screw flights is narrowed and finally pressure fused. Next, while the fused resin moves through the smooth part of the screw, it is shaped to the extent that it can maintain its own shape after extrusion, and is extruded from the tip of the cylinder as a continuous pipe-shaped molded product 9.

Normally, in the extrusion molding method for thermosetting resins, the resin is heated and melted in a cylinder, then introduced into the mold through an adapter and shaped into the final shape. Because the flow path of the resin changes in a complicated way, such as being squeezed with an adapter and re-expanded around a mandrel fixed with a spider, resin stagnation is likely to occur (localized curing reaction progresses, etc.). A slight change in pressure or temperature can cause problems such as rapid curing reactions.Also, in order to overcome the resistance caused by the complicated flow path and extrude the resin while preventing stagnation, a strong extrusion pressure 2 is required. However, when using such a molding method, the extrusion speed is at most about 30 cm/-i-, and it is difficult to obtain a product with good roundness and thickness distribution. be.

According to the above method, the smooth part of the screw and the part of the cylinder in that part play the role of the mold, and the resin flow path is only the gap between the cylinder and the screw, so the resin does not stay at all (but only locally). It does not cause sudden curing reactions due to hardening reactions or changes in pressure or temperature.Also, since the smooth part of the screw, which corresponds to the mandrel in the mold in general molding methods, rotates, it does not cause hardening reactions. The frictional resistance between the resin and the metal part is relatively small, and the extrusion pressure obtained from a normal screw smooth section is sufficient. When using this method, an extrusion speed of 80 cm/m can be easily achieved. It will be done.

The feature of the second forming method is that a die formed of a cylindrical part having an inner diameter approximately equal to the inner diameter of the cylinder of the extruder and a cylindrical part having an outer diameter approximately equal to the outer diameter of the bottom part of the screw tip is attached to the end of the screw. This is an extrusion molding method for thermosetting resin in which the thermosetting resin is mounted close to the die and shaped to the extent that it can maintain its own shape after extrusion inside the die.

This method is characterized by the structure of the die attached to the tip of the extruder and the method of attaching the die, and the extrusion device used can be the same as the one described above.

The screw may be a full-flight type screw that is normally used for extrusion molding of synthetic resins and has a flight all the way to the tip, or a torpedo type screw with a smooth part at the tip, and the shape of the tip may be cylindrical or conical. Figure 5 shows one example of a preferred apparatus.

It is desirable that the distance between the screw tip and the cylindrical part of the die be as close as possible, but it is usually 0.05 to 2 IIJ.
It can be selected as appropriate from the range.

Figure 5 shows an example of a die used in this method, with a die approximately equal to the inner diameter of the cylinder -r'
The resin introduced into the bottom outer die at the tip of the screw and the cylindrical portion having a diameter of <; is shaped and hardened while in a molten state, after passing through a portion of the spider and before exiting. The length from the die inlet to the spider is preferably as short as possible, as long as it is sufficient to sufficiently fix the cylindrical part of the die to prevent thinning of the molded product. Further, the length of the die after the spider can be appropriately selected from the range of usually 1D to 10D, preferably 2D to 7D, and more preferably 2D to 5D (where D indicates the diameter of the cylinder). If the length after the spider is less than 1D, curing may be insufficient or the resin may not be sufficiently fused, making it impossible to obtain a good molded product. Moreover, if it exceeds the IOD, the back pressure becomes too large (so much so that extrusion becomes difficult).

In carrying out this method, the temperature settings of each part of the extrusion device are the same as those described above, and the temperature setting of the die is usually in the range of 50 to 200°C, preferably 60 to 150°C. According to this method, there is almost no change in the flow path of the resin after the tip of the screw of the extruder, so there is no stagnation of the resin at all (local hardening reactions and sudden hardening reactions due to changes in pressure and temperature are prevented). There's nothing I can do to trigger it.

As a modification of the second molding method described above, the cross section of the resin inlet is made equal to the circumferential cross section formed by the cylinder and screw tip of the extruder, and the cross section of the outlet is made equal to the circumferential cross section formed by the extruder cylinder and screw tip. A die designed to lead to a desired shape, such as an irregular shape such as a square? It can also be mounted close to the tip of the screw and shaped within the die to the extent that it can maintain its own shape after extrusion.

[For production]

In the present invention, by using a thermosetting resin molding material for continuous extrusion molding using a scree, the appearance of the molded product is obtained by blending a specific amount of 12 points or less of 503 polymers into a thermosetting resin. It has good properties and can be continuously and stably molded.

Furthermore, if the amount of the polymer with 72 points 5C1'C or less used is less than 1 part by weight, there will be little effect on improving extrusion moldability (it is difficult to form stably, and it often hardens within the extrusion molding shape and causes clogging). If the amount is 100 parts by weight or more, the extrusion moldability will be good, but the molded product may bulge or deform during extrusion molding, making it difficult to obtain a satisfactory molded product.

By using the thermosetting resin composition for continuous extrusion molding using a screw according to the present invention, the molded product has excellent extrusion moldability, is free from defects such as cavities, bulges, deformation, etc., and has excellent roundness. Suitable for producing long extruded products.

The present invention will be further explained below with reference to Examples and Test Examples. In the examples, all parts indicate parts by weight.

Example 1 Novolac resin (Mitsui Toatsu Chemical Novolac resin +20
00, softening point 92-988C) 100 parts, acrylonitrile, butyl acrylate number average molecular weight io, o
oo, 12 points 17 parts of hexamine, 70 parts of wood flour, 30 parts of calcium carbonate, 2 parts of magnesium stearate were added to a thermosetting resin composition consisting of 80 parts of copolymer A at 20°C, and the mixture was heated at 100°C for 10 minutes. The mixture was kneaded with a roll, then cooled and pulverized at room temperature to obtain a molding material.

Example 2 A molding material was prepared using the same materials as in Example 1, except that 7 parts of copolymer A40 were used, and the same formulation was used.

Example 3 The same materials as in Example 1 were used, except that 20 parts of copolymer A and Z were used, and a molding material was made according to the same formulation.Example 4 The same materials as in Example 1 were used, except that 20 parts of copolymer A and Z were used. was used to make a molding material using the same formulation.

Example 5 Novolac resin (Mitsui Toatsu Chemical Novolac resin #20
00, softening point 92-98°C) 1 [) C1 part, styrene,
Number average molecule f? consisting of butadiene? 'E 8,000.
Using 17 parts of hexamine, 70 parts of wood flour, 30 parts of calcium carbonate, and 2 parts of magnesium stearate in a thermosetting resin composition consisting of 10 parts of copolymer B at 72 points -15°C,
The mixture was kneaded with two rolls at 110°C for 5 minutes, cooled, and pulverized at room temperature to obtain a molding material.

Example 6 Epoxy resin (Shell Chemical Co., Ltd., trade name Epicote #1
002, softening point 75-85°C) 160 parts, acrylonitrile, butadiene, number average molecular weight 15.000
．． 72 points A thermosetting resin composition consisting of 10 parts of copolymer C at -12°C, 7 parts of dicyandiamide, 100 parts of calcium silicate, and 30 parts of 3% glass fiber? Use, 100℃,
The mixture was kneaded with two rolls for 5 minutes, then cooled and pulverized at room temperature to obtain a molding material.

Comparative Examples 1 and 2 For comparison, assuming that no copolymer with a T2 point of 50°C or lower was used, copolymer A'Y was not used in Example 1, and the other conditions were as per the usage ratio and conditions shown in Example 1. In the produced molding material 1 and Example 1, copolymer A110
The same materials as in Example 1 were used, except for the different parts used, and molding material 2 manufactured according to the same recipe was used.

Comparative Example 3 Molding material 3 packed according to the usage ratio and conditions shown in Example 5, except that 10 parts of a copolymer of acrylonitrile, styrene, and butyl acrylate with a number average molecular weight of 15,000.17 at 60°C was used. It was used.

Extrusion molding test example 1 An extruder with a diameter of 60X and a L/D = 22 is used for compression with a smooth part with a diameter of 54% and a length of 120X (2D) at the tip following the measuring part with a diameter of 54X at the bottom of the screw. Molding was performed using a screw X with a ratio of 2.0.

The conditions of the extruder are room temperature for 2D from the bottom of the hopper, then 3~
IOD is 60℃, 11-14D is 80℃, 15-18D
Extrusion was performed at 100°C, 140°C for 19-22D, and a screw rotation speed of 35 rpm.

The test results are shown in Table 1.

Extrusion Test Example 2 Supply section 3D by an extruder with a diameter of 40 m and L/D = 24.

Using a compression ratio 2.0 screw Examples 1 to 6 were installed at a position 0.5 length from the tip of the Dyson screw with an outer diameter of 46 II, an inner diameter of 40 mm, a flow path length of 120 m having the same cross section as the outlet side, and a total length of 180 mm. Using the molding materials of Comparative Examples 1 to 3, pipe molding was performed and various tests were conducted.

The extruder conditions are: 2D from the bottom of the hopper is water-cooled, 3-10
D is 70℃, 11-16D is 85℃, 17-20D is 9
5℃, 21-24D is 105℃ and the die part is 30℃.
℃, and extrusion molding was performed at a screw rotation speed of 3 Orpm.

The test results are shown in Table 2.

[Brief explanation of drawings]

FIGS. 1, 2, and 3 show an example of a screw having a smooth portion at the tip used for molding the thermosetting resin molding material of the present invention, and FIGS. 4 and 5 shows one example of a device suitable for the molding.

Claims (1)

[Claims] A screw with a smooth part at the tip is used, and the smooth part is shaped to the extent that it can maintain its own shape after extrusion, or a cylindrical part with an inner diameter approximately equal to the inner diameter of the cylinder of the extruder and the bottom of the screw tip. A die having a die inlet formed by a cylindrical part having an outer diameter approximately equal to the outer diameter is attached close to the tip of the screw, and the product is shaped within the die to the extent that it can maintain its own shape after extrusion. A molding material suitable for continuous extrusion, comprising 1 part by weight or more and less than 100 parts by weight of a polymer having a secondary transition temperature of 50°C or less per 100 parts by weight of a thermosetting resin. Curable resin molding material.