JPS6097813A - Manufacture of high polymeric formed body - Google Patents

Abstract

PURPOSE:To form a high-density and hard formed body for precision machinery component by a method wherein high polymeric material packed in a metal vessel is pressed by exploding. CONSTITUTION:Particles of poly-para-phenylene terephthal amide, the molecular weight of which is 38,000, employed as high polymeric material 4 is packed in a metal vessel 5 and pre-pressed by means of a piston press. After that, the air in the vessel is evacuated through a discharge pipe 7 by means of a vacuum pump and finally the pipe 7 is melted off. Explosive pressing is carried out by exploding powder explosives 3, the main component of which is ammonium nitrate and which are charged in an exterior vessel 6, under the condition that the vessel 5 obtained by the above-mentioned operation is installed in the exterior vessel 6 by energizing the desired current to an electric detonator 1. At this time, the impact pressure applied from above is damped by a clay clot 2 placed on the upper part of the vessel 5. The resultant explosive-pressed formed body is of extremely dense.

Description

[Detailed description of the invention] The present invention relates to a method for producing a polymer molded article.

More specifically, the present invention relates to a method for producing a molded article by molding a polymer material by an explosive compression method.

Conventionally, a method of forming metal powder by explosive compression is known. For example, there is a method in which metal powder is loaded into a cylindrical or prismatic container, surrounded by an explosive layer, and the explosive 1# is detonated to compress and mold the metal powder. (DuPont, Special Publication No. 36-1952; Yokan Nomura, Industrial Chemicals Association Journal 22゜(e) 321-325 (1961)
) Various methods have also been devised to obtain molded bodies of other shapes, such as plate-like or spherical shapes.

(0, V, Roman, V, G, Gorob
tsov, Minsk, 220600.

83 (1979); H, R, Thornton
, D., R. Garrett, SAMPLEQu.
arterly, July 1977, l.
41 (1977)) However, no attempt has been made to apply such a technique to a polymeric material to obtain a molded body.

The reason for this appears to be that polymer materials are much less chemically stable than metals, so there is a fear that carbonization and deterioration will occur if the high impact of explosive compression is applied.

In fact, focusing on the chemical instability of organic compounds, attempts have been made to induce reactions in organic compounds using the high impact generated by explosions, as well as the generation of radicals and induced polarization in polymeric substances. Attempts are being made to cause this to occur. (Yoshio Tanaka, Functional Materials February 1983 issue, 1-12
(1983)). However, in such attempts, the desired reaction is small, but carbonization and decomposition of the material,
Depolymerization has occurred, and this is completely unsuitable for attempts to obtain molded products of polymeric materials.

The present inventors took into consideration various properties of polymer materials, and
As a result of intensive research into phenomena such as carbonization, deterioration, and decomposition of materials due to impact concentration during explosive compression, and measures to prevent them,
Succeeded in obtaining a polymer molded product without deterioration phenomena,
We have arrived at the present invention.

That is, the present invention is a method for producing a polymer molded article, which is characterized by molding a polymer material by explosive compression.

In the present invention, the polymer material refers to a polymer or copolymer made of repeating units, or a precursor for a polymer that has a polymerizable group or a crosslinkable group and can constitute repeating units, and has a molecular weight of 500 or more. It is a high molecular weight substance. Existing and known polymers, copolymers, or precursors thereof can be used as such polymeric materials. An example is Polymer H
andbook (J.Brandrup, E.H.Im
mergut, 1975, John Wiley & So
ns), J. PolymerSci, Macromol
ecular Reviews, 14, 265-378
(1979) (C, Arnold, JR,), Synthetic Polymers Volume I-1 (edited by Murahashi et al., Asakura Shoten), Modern Industrial Chemistry Volumes 16-20 (edited by Oda et al., Asakura Shoten), New Heat-Resistant Polymers ( edited by H. Lee et al., translated by Nagai et al., Kagaku Doujin), Pol
ymer Syntheses Vol I-III (S
．． R. Sandler et al., Academic Press
These are polymers and copolymers, and precursors for polymers having polymerizable groups and crosslinkable groups, which are described in existing literature such as S, Inc., ).

The molecular weight of these polymeric materials must be 500 or more. This is because when the molecular weight is 500 or less, the mechanical properties of the molded product obtained by explosive compression are poor, and for example, it is difficult to cut or cut the molded product itself. There is no upper limit to the molecular weight, and ultra-high molecular weight materials that are difficult to melt and mold in general can also be applied. Further, it is applicable to both meltable materials and non-meltable or difficult-to-melt materials.

To name a few of these polymer materials, polyethylene, polypropylene, polybutadiene, polystyrene,
polyacrylonitrile, polytetrafluoroethylene,
Polyvinyl chloride, phenoxy resin, polyoxymethylene, polyamide, polyimide P and its precursors, polycarbonate, polyester, polysulfone, polyphenylene sulfide, polyphenylene oxide, polymethacrylate, guanamine resin, diallyl phthalate resin,
Phenol resin, unsaturated polyester resin, polyoxy resin, furan resin, polyurethane resin, melamine resin, urea resin, xylene resin, polyvinyl alcohol, aromatic polyamide r1 polybenzthiazole and its precursors,
These include polybenzoxazole and its precursors.

The shape of the polymeric material used in the present invention may be powder, granule, pellet, chip, sorzo, fiber, film, flake, lump, plate, etc., and the shape is not limited.

Generally, it is difficult to directly mold materials with fine shapes such as powder, granules, curds, films, and flakes, but this is possible with the present invention, which is particularly advantageous for materials with these shapes. It's a method.

In the present invention, the method of explosively squeezing the polymeric material is, for example, filling a sample into a metal tube such as a steel tube, packing an explosive around the steel tube, and detonating it with a super explosive such as an electric detonator. A method of generating and squeezing a sample, filling a rubber, plastic, metal or other container, or preforming only the sample, and filling this filling or preform into a metal pipe such as a steel pipe, There is a method of filling the gap between the metal tube and the sample with an inert medium and generating and squeezing it in the same way as above, or filling the sample in a concave container, placing a metal plate on top of it, and then It is possible to utilize methods such as loading gunpowder into the upper part to generate explosives and squeezing them, and other methods conventionally known as explosive squeezing methods for metals.

In carrying out the explosive compression of the present invention, it is necessary to load the polymeric material in a dense state in advance. In other words, it is extremely important that the polymer material be loaded in the sample loading space such as the container space so that it has a bulk density that is at least 0.75 times its true density.
The loading is preferably 0.8 or more, particularly preferably 0.85 or more. Polymer materials, especially when they are in fine shapes such as powders, solps, fibers, flakes, and films, become extremely bulky. Violent movement within the interior causes collisions, concentration of impact, generation of frictional heat, secondary oxidation, etc., resulting in carbonization and deterioration of the material.
May cause decomposition. In order to minimize this phenomenon, in the present invention, it is important to load the bulk density of the raw polymer material at least 0.75 times the true density of the raw polymer material at the pre-loading stage as described above. be. As such a preloading method, for example, a pressurization method such as a purified water pressurization method, a uniaxial unidirectional pressurization method, a uniaxial bidirectional pressurization method, etc. can be used.

Also, during explosive compression of polymeric materials, the inside of the sample container and the sample cavity are evacuated to a pressure of I KPa or less, preferably 100 Pa.
Hereinafter, it is particularly preferable to maintain a vacuum state of 10 Pa or less or replace the molded body with an inert gas such as argon, helium, or nitrogen in order to suppress unnecessary deterioration such as carbonization and oxidation of the compact.

Explosives with various detonation velocities can be used as the explosives for causing the explosion of the present invention, but in general, explosives with detonation velocities ranging from 1000 m/g to 70 m/g can be used.
00 m/a explosive, preferably below 4000 m/a,
Particularly preferably from 15 o m/s to 3000 m/s
It is a low detonation velocity 9 explosive with a detonation velocity of s. this is,
In general, the higher the explosive velocity is used, the higher the pressure can be applied, but on the other hand, it is easy to create a void in the center of the compacted compact, which is thought to be due to the effects of high-level shock waves, and if the explosive velocity is too low, This is because the pressing is insufficient and a satisfactory molded product cannot be obtained.

The amount of explosive to be used is selected depending on the type of explosive to be used, the relationship between the loading method of the explosive and the squeezing method, the shape and type of the polymer material to be squeezed, and the characteristics to be added to the molded article.In general, The conditions can be selected to be 100 parts by weight or less relative to 1 part by weight of the raw polymer material.

The type of explosive may be selected from various known and existing explosives, but some examples include ammonium nitrate as a base material and sensitizers such as TNT, tetryl,
Powdered explosives prepared with hexogen, PETN, combustible materials such as starch and wood flour, and detonation rate modifiers such as salt and talc are highly safe and easy to handle, and the proportions of the ingredients can be changed. This is preferable because desired performance can be obtained by doing so.

The molded product of the present invention obtained in this way has a bulk density that is at least 0.9 times or more, particularly 0.94 times or more, the true density of the raw polymer material. It is a dense molded body.

The explosive compression molded product obtained in this way can be used for the intended purpose by subjecting it to heat treatment, machining such as cutting or cutting, or plastic working, if necessary.

The molded product obtained by the present invention has far superior compactness, high density, and high hardness compared to a general compression molded product that is simply molded under normal static pressure. In addition, even if the molded body is brittle and crumbles even if the molded body is subjected to post-processing such as cutting or cutting in the general compression molding method, the method of the present invention allows the molded body to be integrated so that it can be processed. It also has excellent mechanical properties. Therefore, the molded article of the present invention is useful as a material for parts that require high performance, such as precision mechanical parts and electronic material parts.

Next, the present invention will be explained by examples.

Example 1 64 g of granules (average particle size 300 μm) of polynozorough ethylene terephthalamide (hereinafter abbreviated as PPTA) with a molecular weight of 1 t a s, o o o were used as a polymer material, and this was The metal container 5 shown in the figure with a wall thickness of 2 days and an outer diameter of 30 m (inner volume 55.2 a++ thick, pre-pressed and loaded at 151 MPa with a piston press,
The internal air was evacuated by a vacuum pump through an exhaust gas pipe 7 to a pressure of 1 to 10 MPa, and the nosoip was fused under that condition. The bulk density of the preload is 1.16, and the raw material PP
It was about 0.81 times the true density of TA, which is 1.44.

For explosive compression, a preliminary compression charge is installed as shown in Figure 1, and when the required current is applied to the electric tube 1 at the top to detonate it, it explodes into a powdered explosive 3 whose main component is ammonium nitrate (detonation speed 2500 m/s). The bomb exploded to 1.5 kg, and the explosion proceeded from the top to the bottom, accompanied by a shock wave. At this time, the clay lump 2 at the top of the loading container buffers the impact pressure applied from above and prevents damage to the loading container. The loading container was placed at the center of the explosive so that the shock wave was transmitted evenly, and the distance between the outer container 6 and the metal container 5 (drug thickness) was 40 mm.

The sample thus explosively pressed was cut into slices while still in the metal container, and the hardness of the center portion was measured using a Vickers hardness tester, and the hardness was 32.

In addition, when the sample was cut out and the bulk density was measured, 1.
The true density of the raw material PPTA is approximately 0.096, which is 1.44.
It had doubled. In addition, although the cross section of the molded body cut in the tube direction (vertical direction) was slightly blackish centered around the center on the end-of-explosion side (lower side), no severe deterioration of the material was observed.

Example 2 PPTA granules (maximum particle size 250 μm) were used, the compression during preloading was 79 MPa, and the thickness of the explosive was 60 m.
(explosive amount: 25 kg), and otherwise conducted the same experiment as in Example 1. Is the bulk density of the preload 1.1? The bulk specific gravity of the explosive compression molded product reached 1.40, which was about 0.81 times and about 0.97 times the true density of raw material PPTA, which was 1.44, respectively. Moreover, almost no deterioration was observed in the molded product.

Comparative Example 1 PPTA granules having an average particle size of 400 μm were used, the pre-compression was carried out with almost no pressure applied, and the other conditions were the same as in Example 1. The bulk density of the preload is 0
．． 5, which was 0.35 times the true density of PPTA.

The center of the explosion-molded body became a cavity, and the surrounding area began to turn black and carbonized. This molded body is extremely brittle;
It was something that could not withstand cutting. The bulk density measured by taking a sample only from the periphery of the molded body was 1.1, which was 0.76 times the true density of the raw material PPTA.

Comparative Example 2 Under the conditions of Comparative Example 1, preliminary compression was set to 79 MPa, and preliminary loading was performed, and explosives with an explosive velocity of 7000 m/s were used as explosives. At this time, the thickness of the drug was 15 m. the result,
The bulk density at the preloading stage is 0.9, which is α63 times the true density of PPTA, which is 1.44. On the other hand, after explosive squeezing, the center was completely blackened and decomposed into a hollow cavity, and most of the surrounding areas were also carbonized (blackened).

When explosives with an explosive velocity of 3,500 m/s were used, the surrounding area was not completely carbonized (blackened) but remained extremely brittle.

Example 3 An experiment similar to Example 2 was conducted using a PPTA oligomer with a molecular weight of 3500 and a drug thickness of 55 mm. In addition, the particle size of PPTA used was in the range of 210 to 297 μm and in the range of 210 to 105 μm.

The bulk densities of the preload are both 1.20, and the bulk densities of the molded product after explosive compression are both 1.48, which are 0.83 and 1, respectively, compared to the true specific gravity of PPTA, which is 1.44.
．． It reached 03 times. While the preload was extremely brittle, the explosion-pressed molded product was sufficiently integrated to withstand cutting and cutting, and although the molded product had dry black areas, there was almost no deterioration. . The Vickers hardness of this molded product reached 29, and the raw material particle size range was 210 to 29.
The flexural modulus measured by cutting out a 105 μm molded body (bin spacing 15 m, sample thickness s wm) was 19 GPa.
reached.

Example 4 Polyphenylene sulfite P powder with an average particle size of 20 μm (
Rydon P-4) is used as a polymer material.

An experiment similar to that in Example 1 was conducted using a thin film with a thickness of 75 mm.

The bulk density after pre-press loading was 1.09, and the bulk density of the original explosive press-molded product was 1.21. This corresponds to 0.81 times and 0.90 times the J density i1.34 of raw material polyphenylene sulfide P, respectively. The material in the pre-squeezing stage was extremely brittle and could not be cut, but the explosively pressed material could be cut, and the center had a Vickers hardness of 29.

Although the molded product had a strong brown color, no deterioration was observed.

Example 5 Polyethylene terephthalate powder with an average particle size of 30 μm (
Used as a polymer material with ηsp/c0.57), drug thickness 5
5 mm, and an experiment similar to that in Example 1 was conducted.

Bulk density after pre-compression loading (pressure 151 MPa) 1.
22, the bulk density of the explosive compression molded product is 1.38, and the true density of the raw material polyethylene terephthalate is 1.37, respectively.
Compared to that, it reaches 0.89 times and 1.01 times.

The explosion-pressed molded product was hardly blackened and no deterioration was observed. Also, while the pre-squeezed body is extremely fragile,
The integration had progressed to the point that it could be cut.

Example 6 The same method as in Example 1 was carried out using polyacrylonitrile powder (molecular weight approximately 70,000) with an average particle size of 20 μm. The bulk density after preliminary compression loading was 1.00, and the bulk density of the explosion-pressed molded product was 1.12, which were 0.85 and 096 times, respectively, the true density of the raw material polyacrylonitrile, which was 1.17. The explosive compression molded product has a transparent appearance, is sufficiently integrated to withstand cutting and cutting, and shows no deterioration such as blackening. The Pickers hardness at the center of the molded body was 30.

Example 7 An experiment similar to Example 1 was conducted using polytetrafluoroethylene (Polyflon M-12) with an average particle size of 25 μm and a preliminary compression pressure of 39 MPa.

The bulk density after pre-squeezing is 2.17. What is the bulk density of the explosion-pressed compact? -20, which is 0.99 and i, oo times higher than the true density of raw material polytetrafluoroethylene, which is 2.20. The molded product was not blackish at all, no deterioration was observed, and it was an integrated product with sufficient 0T cutting ability.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the explosive compression device used in Example 1. 1...Electric detonator, 2...Clay, 3...Explosive, 41
Polymer material, 5... Metal container, 6... Outer container, 7
...Exhaust Nozo Eve. Patent applicant Director of the Agency of Industrial Science and Technology 16- No. 3 5 No. 6

Claims (2)

[Claims] 1. A method for producing a polymer molded article, characterized by molding a polymer material by explosive compression. 2. The method for producing a polymer molded article according to claim 1, characterized in that the polymer material is loaded in advance so that the bulk density is 0.75 times or more the true density of the polymer material.