JPS60233129A - Preparation of nylon powder - Google Patents

Abstract

PURPOSE:To obtain porous nylon powder useful as a raw material for sintered nylon, having uniform size and low apparent specific gravity, by dissolving nylon in a solution of calcium chloride or magnesium chloride in methanol under heating, adding an aqueous solution of methanol having a specific concentration to the solution. CONSTITUTION:Nylon is added to a solution of calcium chloride or magnesium chloride in methanol. The solution is heated to dissolve nylon, 50-90wt%, preferably 65-75wt% hot aqueous solution of methanol is added to the solution, which is cooled. The prepared nylon powder has <=0.2 apparent specific gravity.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing nylon powder, more specifically, adding nylon to a methanol solution of calcium chloride or a methanol solution of magnesium chloride and heating the mixture.
A method for producing nylon powder, which comprises dissolving nylon, adding a heated methanol aqueous solution to the solution, and cooling it to precipitate powdered nylon from the nylon solution. The aim is to economically obtain porous and uniformly sized nylon powder.

Nylon is a synthetic resin with particularly excellent abrasion resistance and toughness, and is therefore well known and highly evaluated not only for its use as a fiber but also as a material for industrial parts. For example, it is used in bearings, pushers, cams, ratchets, etc. In addition, the range of use has expanded due to its good vibration and shock absorption properties and corrosion resistance. In particular, nylon sintered bodies have been utilized for their light weight properties, and are now being used in areas where metal sintered bodies have not been used in the past. It has also expanded into other fields.

In order to manufacture a nylon sintered body, it is necessary to mold nylon powder using nylon powder as a raw material. Methods for obtaining nylon powder include mechanical crushing and chemical treatment. Nylon powder, which is a raw material for sintered nylon bodies, is required to be porous in order to suit the intended use. Although it is possible to make the powder particles finer by mechanical grinding, it is not possible to make the powder porous. Furthermore, mechanically grinding into fine particles generates heat, so it is industrially difficult to mechanically grind a polymer compound into fine powder.

Therefore, chemical treatment is currently the most common method for obtaining porous nylon powder as a raw material for nylon sintered bodies. As such a method, in Japan, Tokuko Showa 3! ;-33 to 3, Tokko Sho 3 Otsu-231
2 and Tokko Sho Geter 3/310 are known. but,
These methods use relatively expensive materials such as ethylene glycol and lead powder, and the high melting temperature may cause nylon to hydrolyze, reducing its physical strength. However, there are problems that make it extremely difficult to apply it industrially.

As a result of intensive study from an economic perspective for industrial production, the present inventors selected a well-known solvent system for nylon, a methanol saturated solution system of an inorganic chlorine compound, and Surprisingly, it was discovered that a porous nylon powder could be obtained by adding an appropriate amount of methanol aqueous solution and cooling and precipitating it, leading to the completion of the present invention.

According to the present invention, methanol, which is inexpensive and has a low boiling point, is used instead of a conventional high-boiling solvent such as ethylene glycol, so it is easy to recover and reuse. Moreover, conventionally 100
Since the dissolution temperature, which used to be above .degree. C., can be lowered sufficiently, hydrolysis of nylon is suppressed, and a decrease in the physical strength of nylon can be avoided. Therefore, the method of the present invention is a very economical method for producing porous nylon powder.

Calcium chloride and magnesium chloride used in the present invention may be anhydrous or may contain water of crystallization. The amount used is sufficient as long as it forms a saturated solution of methanol containing these inorganic chlorine compounds as solutes. Also, the amount of methanol used differs depending on the type of nylon to be added. For example, in the case of 4.4-nylon, it is appropriate to use 9 to 20 g of methanol S to 20 to 20 g of nylon. be. Below skg, it takes too long for the nylon to dissolve.
If it is more than 9 in 20, the amount used is too large and is not economical. In addition, the methanol concentration of the methanol aqueous solution added for precipitation is SO~qo wt%, preferably 8~qo% by weight.
It is 73% by weight. The amount of methanol aqueous solution used is
A suitable amount is 1.5 to 3 times the amount of methanol saturated solution of inorganic chlorine compound initially used to dissolve the nylon.

If the methanol concentration of this aqueous methanol solution is 90% or more, the precipitated nylon powder will not be porous, and therefore its apparent specific gravity will become large.

Also.

Below SO%, the precipitated nylon does not become powder but becomes a thread-like block. Nylon that can be used in the method of the present invention is ordinary nylon that is dissolved in a methanol solution of an inorganic chlorine compound, such as Otsu-nylon and Otsu, Otsu-nylon.

As explained above, the characteristics of the present invention are as follows: 1% (J, , Bra
ndrup and E! ,H.

3- Polymer Handbook by Eng.
Page ■-+2/ Engineering interscience
Published by Publishera, z9g+), and an aqueous methanol solution having a methanol concentration of 50 to 90% by weight is added thereto to precipitate nylon. Until now, it has not been known that porous nylon powder can be obtained by such a method, and this is the first method discovered by the inventors.

The present invention will be explained below with reference to Examples, but the present invention is not limited thereto.

Example l.

1/1 methanol in a 101-liter flask with a stirrer
.

Calcium chloride (anhydrous) 300g and 6.3-nylon (Leona/!;00, manufactured by Kaiyakasei Co., Ltd.) were charged and heated under reflux while stirring to completely dissolve the nylon. Next, while maintaining the same temperature, 70% by weight methanol aqueous solution 3. After dropping Jl, it is cooled, the precipitated nylon powder is passed through, washed with water, and then dried to give an apparent specific gravity of 0. / Otsu's nylon powder is obtained. The apparent specific gravity is
J]: S K Otsuko 2o Rubber Compound Test Method 4.
It was measured by f.

Example 2゜Example 1. 6-nylon (cMl manufactured by Toshi)
When similar treatment was performed using o4/l)-g-, the apparent specific gravity was 0. jl was obtained.

Example 3゜In place of calcium chloride as in Example, magnesium chloride was treated in the same manner as Otsu and Otsu-Nylon, and the apparent specific gravity was 0. / I got something.

Reference Example Example 1. After dissolving nylon in the same manner as above, 70
The nylon powder precipitated by cooling without dropping the wt % aqueous methanol solution was treated in the same manner and had an apparent specific gravity (7J≦).

Moreover, the apparent specific gravity of nylon powder obtained in the same manner by dropping 100% methanol instead of a 70% by weight methanol aqueous solution was 0.35.

As mentioned above, the nylon powders obtained in Examples 1 to 3 have smaller apparent specific gravity than the nylon powder of the reference example, which is generally recognized as porous nylon powder, so it is clear that they are porous. be. Therefore, the present invention is a method for producing nylon powder that is significantly more industrially effective than conventional chemical treatment methods.

Patent Applicant: Ouchi Shinko Chemical Industry Co., Ltd. Procedural Amendment July 77th, 1985 Commissioner of the Patent Office Mr. Michibu Uga 1.Display of the incident 1988 Patent Application No. 88/189 2. Name of the invention Manufacturing method of nylon powder 3. Person who makes corrections Relationship to the incident: Patent applicant No. 7/No. 1 5. Number of inventions increased by amendment None 6. Subject of amendment “Detailed description of the invention” column of detailed account 7. Contents of correction Line 11 of page 4 of detailed fortune telling "1.5 to 3 times the amount -1 IO, 5. Correct to 3 times the amount - 1.

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Claims (1)

[Claims] Hotly dissolve nylon in a methanol solution of calcium chloride or a methanol solution of magnesium chloride, and add the methanol concentration! ; A method for producing nylon powder having an apparent specific gravity of 0.2 or less, which comprises adding an aqueous methanol solution of 90% by weight of 0N and performing cooling precipitation.