JPH0413128B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for producing an aromatic polyamide molded article reinforced with the fabric of the present invention.
More specifically, the present invention relates to a compression molding method using special aromatic polyamide particles and a reinforcing fabric. [Prior art] As a method for manufacturing aromatic polyamide molded articles, a precipitant is added to an aromatic polyamide solution produced by solution polymerization to form a slurry, and solid particles are taken out from the slurry and pulverized. A method is known in which a fine powder produced by the above process is preformed and then heated for a long period of time to form a molded product by sintering (Japanese Patent Application Laid-Open No. 49-52251). However, this method is impractical not only because the process is complicated but also because sintering takes a very long time. The present inventors previously proposed a method for manufacturing molded products by compression molding using aromatic polyamide particles having a specific particle structure (Japanese Patent Application No. 61-28014); The molded products obtained by this method have problems such as insufficient impact resistance and large deformation under tension, making them unsuitable for use in fields where they are used under harsher conditions. [Object of the Invention] An object of the present invention is to provide a method for producing an aromatic polyamide molded article with improved impact resistance and dimensional stability by compression molding. [Structure of the Invention] The present invention is characterized in that a large number of microparticles with an average particle diameter of 0.1 to 10 μm are aggregated, and a large number of porous aggregated particles are aggregated to form porous aggregated particles, and the average of the aggregated particles is The particle size is 10~400mμ and the surface area is 1~20mμ.
m ² /g of aromatic polyamide particles together with a reinforcing fabric in a compression molding machine at a temperature of 200 °C.
This is a method for producing an aromatic polyamide molded article, which is characterized by heating and pressurizing the product at a temperature of ~400°C and a pressure of 100 to 2000 Kg/cm ² and maintaining that state for 20 minutes to 5 hours. The aromatic polyamide particles, reinforcing fabric, compression molding conditions, etc. used in the method of the present invention will be explained in detail below. (a) Aromatic polyamide particles The average particle size of the aromatic polyamide particles used in the method of the present invention is 0.1 to 10 μm, preferably 0.2 to 5 μm.
A large number of microparticles of m are aggregated to form porous granules (agglomerated particles), and the average particle size of the aggregated particles is 10 to 400 μm, preferably 50 to 400 μm.
The particles are 300 μm and have a surface area of 1 to 20 m ² /g, preferably 3 to 10 m ² /g. Preferred aromatic polyamides used in the process of the invention include homopolyamides or copolyamides in which 40 mol%, preferably 55 mol% or more of the polymer repeating units are metaphenylene isophthalamide units. Such homopolyamides or copolyamides use isophthalic acid halide as the acid component, metaphenylene diamine as the diamine component, and optionally a small amount of a third component such as terephthalic acid halide, methyl terephthalic acid halide,
naphthalene-2,6-dicarboxylic acid halide,
paraphenylenediamine, 3,4 or 4,4-
It can be produced by condensing these using diaminodiphenyl ether, metaxylylene diamine, or meta- or para-benzoic acid halide. Of the aromatic polyamide copolymerized with such a third component, 20 to 60 mol% of the terephthalic acid component,
In particular, copolyamides containing 25 to 45 mol % give molded articles with improved impact resistance than homopolyamides. The aromatic polyamide forming the particles preferably has an intrinsic viscosity (ηinh) of 0.5 to 4.0 as measured in a solution of 0.5 g of polymer dissolved in 100 ml of N-methyl-2-pyrrolidone at 30°C, and particularly A value of 0.7 to 2.5 is suitable because it has excellent moldability and the physical properties of the molded product are good. In addition, in order to improve the heat resistance of molded products, it is preferable to use an aromatic polyamide whose polymer chain ends are blocked with a monofunctional aromatic compound such as aniline or benzoyl chloride. It is preferable that the amount of aromatic nuclear terminals is 20 to 50 mol% relative to the amount. This aromatic polyamide can contain a matting agent, a coloring agent, and a filler if necessary, but
It is better not to contain substances that impair the heat resistance of the molded product, such as inorganic salts such as lithium chloride and calcium chloride. The aromatic polyamide particles used in the present invention are composed of the aromatic polyamide described above, but unlike the powder produced by the conventional precipitation-pulverization method, they are made by agglomerating a large number of microparticles having a specific average particle size. Porous aggregated particles are formed that have a specific average particle size that is much larger than the fine particles. The average particle size of the microparticles is 0.1~10μ
m, preferably within the range of 0.2 to 5 μm, and the average particle size of the porous aggregated particles is
It is in the range of 10 to 400 μm, preferably 50 to 300 μm. Although the agglomerated particles are porous, their surface area is much smaller than that produced by conventional precipitation-pulverization methods, ranging from 1 to 20 m ² /g, preferably from 3 to 10 m ² /g. . That is, the aromatic polyamide for compression molding used in the method of the present invention has an almost spherical or cylindrical mass as a whole, but is porous like pumice. This porous structure is formed by agglomeration of countless fine particles. Therefore, countless minute voids or cavities exist on the surface and inside of the aggregated particles. Therefore, the apparent bulk density of the particles is
It is usually in the range of 0.2 to 0.4 g/cm ³ , which is a much smaller value than the density of the polymer. and,
Despite the porous structure of the particles, conventional aromatic polyamide particles (surface area 50-80 m ² /g)
The fact that the surface area is relatively small (1 to 20 m ² /g) means that most of the cavities and voids within the particles exist independently and are not connected to the surface. Presumed. The methods for measuring the average particle diameter, surface area, apparent density, etc. mentioned here are as follows. (a) Average particle size Take a micrograph of the aggregated particles (100x magnification), determine the particle size of 100 randomly selected particles from the microscope photo, and use the average value as the average particle size of the aggregated particles. In addition, we took magnified micrographs (5000x magnification) of 10 of the aggregated particles, randomly selected 10 microparticles visible on the surface of the aggregated particles in each photo, and measured the particle size of each in the micrograph. The average value is determined as the average particle size of the microparticles. (b) Surface area Using an automatic surface area measuring machine model 2200 manufactured by Micrometrics Instruments, USA,
Measure the surface area of the dried particles by nitrogen adsorption method. (c) Apparent bulk density The volume of a sample in which dried particles are poured into a graduated cylinder (volume 5 ml) with a funnel-shaped entrance so as to flow down along the inner wall of the cylinder, and the graduated cylinder is loosely filled without tapping the cylinder. and weight. Such porous aggregated particles of aromatic polyamide can basically be produced according to the interfacial polymerization method described in Japanese Patent Publication No. 47-10863. According to this interfacial polymerization method, polymer particles with good heat resistance can be obtained since no inorganic salt is contained in the obtained polymer. In order to obtain the aromatic polyamide particles specified in the present invention, it is necessary to appropriately control the conditions of the first reaction and/or the second reaction in the interfacial polymerization method. In particular, in the interfacial polymerization, it is preferable to adjust the reaction as in the second reaction in order to produce the above-mentioned special aromatic polyamide particles. (a) The volume ratio (v) of the dispersion of the initial condensate and the aqueous solution of soda carbonate, etc. should be 0.4 to 0.6. However, v = dispersion of the initial condensate (vol) / {dispersion of the initial condensate (vol) + aqueous solution of soda carbonate, etc. (vol)} (b) Set the tip speed of the stirring blade in the secondary reaction tank to 10
Must be at least m/sec. In addition, in the first reaction, by adding an appropriate amount of a monofunctional aromatic compound such as aniline, the ends of the polymer chain are blocked with the monofunctional aromatic compound and the thermal stability of the polymer is improved. be able to. The particles obtained by the interfacial polymerization method can be used as they are, or further washed with water, dried, and if necessary, further sieved to obtain compression molding particles used in the method of the present invention. (b) Reinforcing fabric The reinforcing fabric to be used with the aromatic polyamide particles described above is not particularly limited as long as it has a reinforcing effect, but particularly preferred fabrics include aromatic polyamide. textile fabric,
Knitted fabrics, non-woven fabrics, unidirectional prepreg sheets (fibers arranged in one direction and hardened with resin)
Alternatively, a unidirectionally aligned prepreg sheet of carbon fibers may be used. As the aromatic polyamide fiber, poly(m-
phenylene isophthalamide) fiber, poly(p
-phenylene terephthalamide) fiber, poly(p-phenylene/3,4'-diphenyl ether terephthalamide) copolymer fiber, and as the carbon fiber, PAN-based carbon fiber,
High performance pitch carbon fiber is used. In the case of woven or knitted fabrics, a fabric weight of 25 to 300 g/ ^m2 is appropriate, and for non-woven fabrics, a fabric weight of 20 to 200 g/m2 is appropriate.
g/m ² is suitable. Further, as a prepreg sheet, one having a fiber weight of 25 to 300 g/m ² is suitable. The reinforcing fabric may be made of two or more types of fibers, for example, a fiber using poly(p-phenylene terephthalamide) fibers for the warp and poly(m-phenylene isophthalamide) fiber for the weft. You can also use (c) Compression molding According to the method of the present invention, the above-mentioned aromatic polyamide particles and reinforcing fabric are both subjected to compression molding to form a molded product. Preferably, the material is compressed and solidified into a layer or sheet, and then one or more layers are laminated with one or more fabrics, and then preformed by compressing and integrating the fabric. In the laminated form, the fabric may be unevenly distributed on one side of the preform, or the fabric may be present as an intermediate layer of the preform. When the fabric is a unidirectional prepreg sheet, it is preferable to laminate the sheets so that the fiber alignment directions intersect with each other. In addition, 2 fabric-like materials
It is also possible to use more than one species in combination. The proportion of the reinforcing fabric used in the aromatic polyamide particles is 20 to 90% by weight, preferably 30 to 90% by weight.
A range of 80% by weight is adopted. At the time of molding, pigments and inorganic additives (for example, carbon powder, alumina oxide, gypsum, etc.) can be used in combination with the above-mentioned aromatic polyamide particles and fabric-like material, if necessary. To perform compression molding, a compression molding apparatus similar to that used for conventional compression molding of thermosetting resins and the like can be used. The compression molding conditions are as follows:
Mold temperature 200~400℃, pressure 100~2000Kg/ ^cm2 ,
Preferably the time is 60 to 180 minutes. During compression molding, the atmosphere should be vacuum or _N2 ,
It is preferable to seal it with an inert gas such as He to keep it out of contact with air. The compression-molded product can be cut into a desired shape (eg, gear shape, etc.). [Effects of the Invention] According to the method of the present invention, not only can a desired molded product be obtained all at once by compression molding, but also
Compared to the case where no reinforcing fabric material is used, the dimensional stability of the molded product against tension is improved, and
It has improved impact resistance and can be used effectively in fields where it is used under harsher conditions than conventional molded products. Therefore, molded products produced by the method of the present invention are particularly useful as printed circuit boards and mechanical parts. [Example] Next, an example of the present invention will be described in detail. In addition, "Konex" in the example refers to poly(m) manufactured by Teijin Ltd.
-phenylene isophthalamide) fiber. In addition, "Technora" is a poly(p-
Phenylene/3,4' diphenyl ether terephthalamide) copolymer fiber. Example 1 Poly(metaphenylene isophthalamide) was prepared according to the interfacial polymerization method described in Japanese Patent Publication No. 47-10863.
A system polymer was produced. In other words, 173 g of metaphenylenediamine was dehydrated with sodium metal and 1
This was cooled to 0°C. On the other hand, 325 g of isophthaloyl chloride was dissolved in 1 of tetrahydrofuran dehydrated with metallic sodium and cooled to 0°C. Next, the tetrahydrofuran solution was stirred while being maintained at 0° C., and the isophthalic acid chloride solution was gradually added thereto as a trickle to obtain a dispersion of the initial condensate (first reaction). Next, the dispersion of the initial condensate was added to sodium carbonate.
200 g of the solution was quickly added to a solution of 2 parts of water under vigorous stirring to obtain day-colored polymer particles having an intrinsic viscosity of 1.8. At this time, various average particle sizes were produced by changing the stirring conditions for the secondary reaction and the volume ratio of the dispersion of the initial condensate to the aqueous sodium carbonate solution. After washing and drying these particles, each particle was observed under a microscope and found to be porous aggregated particles. Next, the average particle diameter, apparent bulk density, surface area, etc. of the particles in each experiment were measured, and the results were as shown in Table 1.

[Table] Next, compression molding was performed using various fabrics as reinforcing materials. (1) Experiment A: Cornex fabric 7 g of the particles obtained in Experiment No. 2 were uniformly placed in a mold heated to 150°C with a width of 50 mm and a length of 100 mm, and compressed at a pressure of 300 kg/cm ² for 3 minutes. , molded into a sheet. Next, a Cornex plain weave fabric (constituent yarn count: 60 single yarn in both vertical and horizontal directions) with a width of 50 mm, a length of 100 mm, and a basis weight of 50 g/m ² was placed on the sheet in the mold, and on top of that, the fabric in Experiment No. 2 was placed. 7g of the obtained particles were uniformly added and heated at a pressure of 300Kg/ ^cm2 .
It was compressed for minutes and formed into a sheet. This operation was repeated two more times to obtain a sheet-like product having a thickness of 4 mm and three layers of three cloths spaced apart by 1 mm. While this sheet-like material was placed in the mold, the mold temperature was raised to 350° C., and compression molding was performed at a pressure of 700 kg/cm ² for 30 minutes. During molding, the molded area is replaced with nitrogen in advance.
Care was taken to prevent the polymer from coming into contact with air during molding. (2) Experiment B...Technora woven fabric Instead of the Cornex plain woven fabric in Experiment A, Technora plain woven fabric with a basis weight of 110 g/ ^m2 was used.
All other operations were the same as in (1) above to produce a molded article. (3) Experiment C...Carbon fiber 7 g of the particles obtained in Experiment No. 2 were uniformly placed in a mold heated to 150°C with a width of 50 mm and a length of 100 mm, and compressed for 3 minutes at a pressure of 300 Kg/cm ² It was then molded into a sheet. Next, carbon fibers (Torayca T-300) were cut into lengths of 100 mm and arranged on the sheet-like material in the mold at 1 mm intervals. Furthermore, Example 1 and Experiment No. 2
7 g of the particles obtained above were uniformly added and compressed for 3 minutes at a pressure of 300 kg/cm ² to form a sheet. Repeat this operation two more times and use one coat at a thickness of 4 mm.
A sheet-like material having three layers of carbon fibers spaced apart by mm was obtained. While this sheet-like material was kept in the mold, the mold temperature was raised to 355° C., and compression molding was performed at a pressure of 700 Kg/cm ² for 30 minutes. The physical properties of the textile-reinforced aromatic polyamide molded products obtained in each of the experiments A, B, and C were compared with those of molded products compression-molded under similar conditions without using textiles, and the results were as shown in Table 2.

【table】

Claims (1)

[Claims] 1. A large number of microparticles with an average particle size of 0.1 to 10 μm are aggregated to form porous aggregated particles, and the average particle size of the aggregated particles is 10 to 400 μm, and the surface area is 1. Aromatic polyamide particles of ~20 m ² /g are heated and pressed together with a reinforcing fabric in a compression molding machine at a temperature of 200 to 400°C and a pressure of 100 to 2000 Kg/cm ^{2 ,} and then kept in that state for 20 minutes to 50 minutes. A method for producing an aromatic polyamide molded product, which is characterized by being maintained for a period of time. 2. The manufacturing method according to claim 1, wherein the aromatic polyamide particles and the reinforcing fabric are pre-compressed and then supplied to a compression molding device and heated and pressurized. 3 Claim 1 in which the amount of reinforcing fabric is 20 to 90% by weight based on the aromatic polyamide particles
The manufacturing method described in item 1 or 2. 4. The manufacturing method according to claim 1, 2, or 3, wherein the reinforcing fabric is a woven fabric made of aromatic polyamide and having a basis weight of 25 to 300 g/ ^m2 . 5. The manufacturing method according to any one of claims 1 to 4, wherein the reinforcing fabric is a carbon fiber prepreg sheet. 6. The manufacturing method according to any one of claims 1 to 5, wherein the aromatic polyamide constituting the aromatic polyamide particles is poly(m-phenylene isophthalamide). 7. The manufacturing method according to any one of claims 1 to 6, wherein the manufacturing method is maintained in a non-contact state with air during heating and pressurization.