JPS5947696B2 - Method for producing porous polyamide powder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a suitable method for efficiently producing porous polyamide powder with excellent adsorption performance.

Polyamide powder has conventionally been known as an adsorbent, and various methods have been proposed for powdering polyamide resin.

The most typical method is to mechanically crush polyamide chips using a ball mill or the like.

However, such mechanical pulverization methods have the disadvantage that pulverization takes a long time and is inefficient due to the high strength of polyamide. Furthermore, the temperature rises due to the friction of the machine, often exceeding the melting point of the polyamide, which causes trouble in that once the powder has been pulverized, it fuses again and cannot be pulverized. For this reason, pulverization is carried out while cooling using an appropriate means, but this method cannot be said to be economically advantageous since cooling equipment and costs are naturally added. In addition, most of the powders crushed by such mechanical methods are roughly spherical in shape;
Moreover, since it is non-porous, even if it is pulverized to a small average particle size, the surface area per unit weight part is small and its performance as an adsorbent is poor. On the other hand, in addition to the above-mentioned mechanical grinding method, a so-called reprecipitation method has also been proposed, in which polyamide is dissolved in a suitable solvent at high temperature and pressure, and the solution is cooled and powdered.

The polyamide solvent used in this reprecipitation method is
For example, in US Pat. No. 2,639,278, polyhydric alcohols such as ethylene glycol, propylene glycol, trienlene glycol, or glycerin are
Further, US Pat. No. 3,130,181 describes aqueous solutions of aliphatic and alicyclic ketones, respectively. However, this method of dissolving polyamide under high temperature and high pressure and reprecipitating it inevitably requires a container that can withstand high pressure, and the manufacturing and maintenance costs and energy costs for raising the temperature are high. However, like the mechanical crushing method described above, it is economically disadvantageous.

As yet another method, JP-A-49-32946 proposes a method of producing granular polyamide by dissolving polyamide in an aqueous hydrochloric acid solution and dropping water or an aqueous alkaline solution thereto. Further, similar to this method, a force method in which polyamide is dissolved in an acid and then reprecipitated with a dilute acid of the same type is also described in Japanese Patent Publication No. 38-13520. However, this method of dissolving polyamide in acids and reprecipitating it causes variations in the particle size of the resulting powder, and also tends to cause depolymerization due to the acid amide bonds in the polyamide being broken. The body's heat resistance decreases, and
There are drawbacks such as a decrease in the number of acid amide bonds that serve as adsorption seats, and it is difficult to obtain a powder with excellent adsorption performance. In view of the above-mentioned drawbacks of conventional technology, the inventors of the present invention have conducted extensive studies in order to find a more economically advantageous manufacturing method for polyamide powder. The inventors have discovered that porous polyamide powder can be obtained efficiently and at low cost by dissolving polyamide in an aliphatic alcohol solution and then adding water while stirring, and have completed the present invention. be. It has been found that the force method of the present invention not only has the advantage that polyamide powder can be produced more economically than the conventional method, but also has the following unexpected and remarkable effects.

In other words, the polyamide powder obtained by the method of the present invention has a porosity that could not be obtained by the conventional method, and electron micrographs show that countless pores are formed on its surface. Confirmed.

This means that the surface area per unit weight is large, and the adsorbent has extremely favorable properties. The force method of the present invention will be explained in detail below. The first feature of the present invention is that an aliphatic alcohol solution containing a carbon number of 4 or less and containing an alcohol-soluble deliquescent inorganic compound is used as the solvent for dissolving the polyamide.

When an alcoholic solution containing such a deliquescent inorganic compound is used, polyamide can be dissolved at room temperature or by only slight heating, and no high-temperature, high-pressure equipment is required as in the case of dissolving polyamide in conventionally known organic solvents. do not. Therefore, the thermal energy required for melting can be significantly reduced. The amount of the deliquescent inorganic compound to be dissolved in the aliphatic alcohol solution having 4 or less carbon atoms is 5 to 80% by weight (hereinafter %
indicates weight % unless otherwise specified.

) is a necessary condition from the viewpoint of workability and the characteristics of the powder obtained. A second feature of the present invention is that the polyamide is dissolved in the alcohol solution containing the deliquescent inorganic compound in a weight fraction of 15% or less with respect to the solution.

The amount of dissolved polyamide greatly influences the properties of the obtained powder. That is, when the amount of polyamide to be dissolved is small, a fine powder is obtained. Ichiryoku 15%
If the amount is close to , the resulting powder will take on a flake-like appearance. If the amount of dissolved polyamide exceeds 15%, it is not preferable because it becomes very hard and flaky with few pores, and its performance as an adsorbent deteriorates.

The most suitable amount of polyamide dissolved naturally varies depending on the type of polyamide, but is usually in the range of about 5 to 14%. When such a range is used, it is possible to efficiently produce powders with various particle sizes depending on the amount. The term "powder" in the present invention does not refer only to powder, but also includes flake. When the amount of polyamide dissolved is 15% or less as described above, the resulting powder, whether in the form of powder or flakes, is porous with many pores, and the adsorption performance is poor. It was confirmed that an excellent product could be obtained.

Alcohol-soluble deliquescent inorganic compounds that can be applied to the force method of the present invention include calcium chloride, lithium chloride, zinc chloride, aluminum chloride, ferrous chloride, ferric chloride, bismuth chloride, magnesium chloride, and nickel chloride. , chlorides such as copper chloride, cerium chloride, nitrates such as aluminum nitrate, calcium nitrate, cerium nitrate, ferric nitrate, nickel nitrate, magnesium nitrate, lithium nitrate, ammonium thiocyanate, potassium thiocyanate, calcium thiocyanate, thiocyanate Thiocyanates such as barium acid, sodium thiocyanate, magnesium thiocyanate, iodides such as aluminum iodide, calcium iodide, nickel iodide, magnesium iodide, lithium iodide, aluminum bromide, calcium bromide, bromide Bromides such as titanium, ferric bromide, copper bromide, nickel bromide, magnesium bromide, and lithium bromide are applicable.

Further, as the polyamide applicable to the present invention, nylon 6, nylon 66, nylon 4, nylon 8, nylon 11, nylon 6/66, etc. are suitably applied, and furthermore, N-substituted nylon, such as N-methyl nylon. ,
N-methylol nylon, N-methoxymethyl nylon, N-ethoxymethyl nylon, N-isopropyl nylon, etc. can be similarly applied. In the method of the present invention, as a method for dissolving 15% or less of polyamide in an aliphatic alcohol solution containing 5 to J8O% of a deliquescent inorganic compound, various methods as described above can be employed.

That is, in addition to the method of dissolving the polyamide in the alcohol solution in a single step to a concentration of 15% or less, the method of dissolving the polyamide in an amount of 15% or more in advance and then adding a deliquescent inorganic compound in which the polyamide is not dissolved. There is no problem in adopting two methods in which the polyamide is prepared in a two-stage process by adding only an alcohol solution or by adding only alcohol so that the final amount of polyamide dissolved is 15% or less. When water is added while stirring to the aliphatic alcohol solution in which a predetermined amount of the polyamide thus prepared is dissolved, the polyamide reprecipitates and precipitates out.

The precipitated polyamide is filtered off and thoroughly washed with water to obtain the porous polyamide powder of the present invention. The polyamide powder of the present invention obtained in this way has a porosity with countless pores on the surface, which could not be obtained by the conventional method, and has extremely excellent performance as a suction bar. It is something that exists.

In the present invention, the reason why the polyamide powder produced exhibits porosity has not yet been fully elucidated, but
Presumably, the deliquescent inorganic compound used in the present invention coordinates with the -CONH- group of the polyamide, becomes encapsulated in the polyamide precipitate when water is added to precipitate it, and is then encapsulated in the polyamide precipitate during the subsequent water washing step. It is presumed that the coordinated deliquescent inorganic compound creates pores when it dissolves into water. Such a unique effect of the present invention was not observed in the conventional dissolution-reprecipitation method, and was an unexpected result. The most effective use of the polyamide powder of the present invention as an adsorbent is the adsorption and removal of polyphenols in vegetable beverages.

In other words, if polyphenols are present in excess in beverages made from plants such as beer, wine, and fruit juice, they will exhibit unfavorable quality phenomena such as turbidity and browning.
In the beverage manufacturing industry, adsorbents for selectively adsorbing and removing polyphenols are widely used. The polyamide powder of the present invention has the ability to selectively adsorb polyphenols in particular, and is suitably used as the above-mentioned adsorbent.

In order to remove polyphenols, the polyamide powder obtained by the force method of the present invention is used in the manufacturing process of these beverages, for example, the polyamide powder obtained by the force method of the present invention is used. packed in a cylindrical column through which intermediate processing of these beverages is passed, or
The polyamide powder obtained by the force method of the present invention is added to the intermediate process of these beverages, and after stirring, the polyamide powder is filtered through filter paper, filter cloth, etc., or the polyamide powder is separated by filtration. The polyamide powder obtained by the method of the invention may be mixed with cellulose to make a receipt-like product, and the intermediate process of making these beverages may be filtered.

However, the method is not necessarily limited to these methods, and the point is that the polyamide powder obtained by the force method of the present invention should come into contact with these beverages in some way. Plant-based beverages treated with these methods no longer have quality defects such as cloudiness and browning. In addition to the above-mentioned methods, the polyamide powder obtained by the force method of the present invention can be used to remove substances such as polyphenols, nicotine, and tar in cigarette smoke.

The present invention will be explained in more detail with reference to Examples.

Example 1 Calcium nitrate 400V was dissolved in methanol 600t, nylon 6 powder 1000v was put into this solution, and 5
The mixture was dissolved at 0° C. with stirring for 30 minutes.

Pour 2 hours of methanol into this solution and add 4 hours of water while stirring well.
A liquid solution was added to reprecipitate the nylon 6 powder into the liquid.
This nylon 6 powder was filtered through a Buchner funnel and heated to 45°C.
Rinse with 5 tons of hot water, then rinse with 0.5 tons of acetone,
It was dried in a hot air dryer at 60° C. for 2 hours to obtain a nylon 6 adsorbent. Separately, for comparison, the same nylon 6 powder was mechanically pulverized in a ball mill to obtain a powder with an average particle size of 200 mesh. Both of these were poured into 100ml of commercially available beer, stirred for 5 minutes at 2°C, separated by filtration, and the amount of polyphenol in the filtrate beer was measured by the Harris method.

The results are shown in Table 1. From the results in Table 1, it can be seen that the adsorbent prepared by the method of the present invention has excellent ability to adsorb all polyphenols.

Example 2 300t of magnesium thiocyanate was mixed with 600t of ethanol
ft, and 50 tons of nylon 4 chips were put into this solution, heated to 50° C., and dissolved while stirring.

Next, 4 tons of water was gradually added to this solution while stirring to obtain a precipitate of nylon 4 adsorbent. (This is Example 1
A nylon 4 adsorbent was obtained by washing with water and drying in the same manner as above. )
As a separate comparison, the same 40t nylon 4 tip is 6N
It was dissolved in 2 tons of hydrochloric acid, and 3 tons of water was added thereto to obtain a powder of nylon 4.

This material was filtered through a Buchna funnel, washed with water, and dried.
1 ton of each of these was added to a 100% aqueous solution of D-catechin 100P, which is a type of polyphenol, and after stirring for 5 minutes, nylon 4 was filtered off, and the remaining amount of D-catechin in the filtrate was determined by external absorption. Ta.

The results are shown in Table 2. As is clear from Table 2, the nylon adsorbent prepared by the method of the present invention has an excellent adsorption amount of D-catechin.

Example 3 300 tons of lithium iodide was dissolved in 700 tons of ethanol, and 60 liters of nylon 6 chips were added to this solution and dissolved at room temperature.

While stirring this solution, 3 tons of water was added to obtain a precipitate of nylon 6. The precipitate of nylon 6 was filtered through a Buchna funnel, washed with 3 tons of warm water at 50°C, further washed with 1 ton of acetone, and dried in a hot air dryer at 70°C for 3 hours to obtain flaky nylon 6. An adsorbent was obtained. As a comparison,
The same nylon 6 chips were mechanically ground in a ball mill to obtain chips with an average particle size of 250 mesh.

2 tons of each of these were added to white wine 200α, stirred for 10 minutes, nylon 6 was filtered off, and the amount of anthocyanogen, a type of polyphenol, in the filtrate was determined with hydrochloric acid-n.
- Measured by the butanol method.

The results are shown in Table 3. As is clear from Table 3,
The adsorbent prepared by the method of the present invention has a better anthocyanogen absorption ability.

Example 4 500 tons of aluminum chloride was dissolved in a mixed solvent of 300 r of methanol and 200 tons of ethanol, and 80 f of VCN-methyl nylon 6 (degree of methylation: 5%) was dissolved in this solution.

2 tons of water was added to this solution to obtain a precipitate of N-methylnylon 6. Next, the precipitate of N-methyl nylon 6 was filtered using a Buchna funnel, washed with 4 tons of 45°C warm water, and then dried.
A flaky N-methyl nylon 6 adsorbent was obtained. 20 liters of this material was poured into 10 tons of water and dispersed using a homomixer. 50 tons of bleached sulfite pulp made from coniferous trees was added to this dispersion and continued to be dispersed using a homomixer, and then put into a hand paper machine. A filter paper-like sheet measuring 20 x 25 cm was prepared.

Claims (1)

[Claims] 1. Into an aliphatic alcohol solution having 4 or less carbon atoms containing 5 to 80% by weight of an alcohol-soluble deliquescent inorganic compound,
Polyphenol adsorption characterized by dissolving 15% or less of polyamide in weight fraction in the solution, then adding water with stirring to precipitate the polyamide, and then washing the polyamide precipitate with water. Method for producing porous polyamide powder for use.