JP2988136B2 - Method for producing metal ion crosslinked polymer fine powder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a fine powder of a metal ion crosslinked polymer such as a metal polyacrylate.

[0002]

2. Description of the Related Art Polymers crosslinked at high density with metal ions such as metal polyacrylates are expected to be a metal substitute polymer because of their high heat resistance, isotropic and high elastic modulus. To produce this metal ion crosslinked polymer, for example, JP-A-62-74905 and JP-A-62-74905
As disclosed in JP-A-74906 and JP-A-62-259818, polyacrylic acid and an inorganic metal salt are reacted at a predetermined ratio in an aqueous solution of an alkali metal hydroxide to form a precipitate. This is filtered and dried to obtain a polymer powder.

[0003]

However, this metal ion cross-linked polymer powder is heat-infusible, so that a general resin molding method cannot be used. Further, since the particles have a large particle size, are indefinite, and have low fluidity at the time of molding, a high pressure of several thousand kg / cm ² or more is required at the time of heat compression molding, and the man-hour required for molding is large.

In order to improve the fluidity at the time of molding in order to reduce the pressure at the time of molding, the metal ion crosslinked polymer powder may be miniaturized. However, the metal ion-crosslinked polymer precipitate obtained by the above-mentioned production method has a property of agglomerating during drying, and the particle size of the obtained dry powder is as small as 0.1 mm. As a method of remaining fineness, there is a method of physically pulverizing. However, in this case, the fluidity during molding is improved,
The pulverization causes considerable damage to the structure of the metal ion crosslinked polymer, which may adversely affect the physical properties of the molded article.

The present invention has been made in view of the above circumstances, and has no fear of damaging the polymer structure.
It is intended to produce a fine metal ion crosslinked polymer powder.

[0006]

A process for producing a metal ion-crosslinked polymer fine powder which solves the above-mentioned problems comprises reacting metal ions in an aqueous solution of a hydroxide of at least one of an alkali metal and an alkaline earth metal. A precipitating step of precipitating the metal ion cross-linked polymer by reacting the metal ion with the cross-linkable polymer raw material and precipitating the metal ion cross-linked polymer; And a process.

Polyacrylic acid is typically used as a polymer material that can be crosslinked by reacting with metal ions.
This polyacrylic acid is 80-100 mol% acrylic acid
And 20 to 0 mol of another vinyl monomer. The degree of polymerization of the polyacrylic acid is 500,000 to 1,250,000 in number average molecular weight, and preferably 100 or more. In addition, any polymer material, such as polymethacrylic acid, polystyrene carboxylic acid, and polystyrene sulfonic acid, which can be dissolved and dissolved in a solvent and can form an ion bond with a metal ion can be used.

The alkali metal or alkaline earth metal supplied as a hydroxide activates a functional group of a polymer raw material to promote a reaction with a metal ion supplied from a metal salt. , K, Li, Ca, B
Metals such as a and Sr are used. Among them, it is preferable to use metals such as Na and K having strong basicity. Examples of the metal ions that react with and crosslink with the polymer raw material include Z
n, Mg, Ca, Ba, Sn, Fe, Pb, Cu, C
o, salts of divalent metals such as Ni, Mn, Cr, Al, La
Trivalent metal salts such as Ti, Zr, Te, and Ru
Metal ions dissociated from salts of valent metals can be used.

The mixing ratio between the metal ion and the polymer raw material is as follows:
The ratio of the metal ion can be 0.1 to 20 equivalents to 1 equivalent of the carboxyl group of the polymer raw material. In the precipitation step, the polymer raw material and metal ions react in a solution, and a metal ion crosslinked polymer is precipitated and precipitated. It is also preferable that a fibrous or powdery reinforcing material coexist in the solution. By doing so, the reinforcing material is taken in and precipitated simultaneously with the precipitation of the metal ion crosslinked polymer, and the metal ion crosslinked polymer fine powder containing the reinforcing material can be easily produced.

In the drying step which is a feature of the present invention, the obtained precipitate is spouted and dried in a wet state before drying. For example, the precipitate is pumped up by a pump or the like and ejected into a hot air stream. By doing so, the precipitate is refined by the wind pressure of hot air and dried in that state, so that a fine metal ion crosslinked polymer fine powder can be obtained. The precipitate may be blown out under a reduced-pressure atmosphere and dried, or may be blown and dried on the surface of a rotating heat drum.

Note that the once dried metal ion crosslinked polymer fine powder does not aggregate even if it is in a wet state during washing, and maintains a fine state after washing and drying.
Therefore, the obtained metal ion crosslinked polymer fine powder can be subjected to molding after washing and drying.

[0012]

According to the method for producing a metal ion-crosslinked polymer fine powder of the present invention, a precipitate of the metal ion-crosslinked polymer is jetted in fine particles in a wet state. This precipitate hardly causes aggregation during the wet state and has a certain degree of freedom, so that it can be easily formed into fine particles. Further, since the particles are formed into fine particles in a wet state, the surface tension of the solution acts, and the particles become substantially spherical particles. Then, the metal ion-crosslinked polymer fine powder which has been dried in that state and once dried does not aggregate even if it is again brought into the wet state. Therefore, by repeating washing and filtration, a metal ion crosslinkable polymer in the form of a fine powder having a substantially spherical shape and high purity can be obtained.

[0013]

The present invention will be specifically described below with reference to examples. Example (1) Precipitation Step In a polyethylene beaker, 3400 cc of an aqueous solution containing 31.4 g of polyacrylic acid having a number average molecular weight of 250,000, and N
1100 cc of an aqueous solution containing 20 g of aOH is charged and sufficiently stirred. Then, while continuing stirring, AlCl ₃ 60
2600 cc of an aqueous solution containing g is gradually dropped, and polyacrylic acid is reacted with AlCl ₃ . Stirring is continued for about 10 minutes even after the entire amount has been dropped, to converge the reaction. As a result, the reaction product precipitates, and when the stirring is stopped, an Al ion crosslinked product of polyacrylic acid is obtained as a gel precipitate.

[0014] The mixing ratio of each raw material used in the above synthesis, polyacrylic acid 0.44 eq, NaOH0.52 equivalents are AlCl ₃ 1.36 eq, excess of a NaOH and AlCl ₃ to polyacrylic acid Was blended in. (2) Drying Step As shown in FIG. 1, the gel precipitate 40 in the beaker 4 is
It was pumped up using a pump 3 and supplied from a spray nozzle 30 to a drying device.

The drying apparatus comprises a drying chamber 1 having a heater 10 on the wall surface as shown in FIG. 1, and a supply path 2 opening on the upper side wall of the drying chamber 1. Is provided with a breathable collection bag 11. Hot air is supplied to the supply path 2 from one end toward the drying chamber 1. The supply path 2 has a reduced diameter portion 20 at an intermediate portion, and an injection nozzle 30 connected to the pump 3 is connected to the reduced diameter portion 20 so as to communicate therewith. A heater 21 is also provided downstream of the reduced diameter portion 20 of the supply path 2. Further, a heater 31 is also provided in a flow path from the pump 3 to the injection nozzle 30.

In the above-mentioned drying apparatus, the temperature inside the drying chamber 1 and the downstream side of the reduced diameter portion 20 of the supply path 2 is set to 200 ° C.
It is preheated to 0 ° C. The blowing speed of the hot air was set to 60 m / sec near the injection nozzle 30, and the precipitate was ejected from the injection nozzle 30 at a flow rate of 10 cc / sec into fine particles.

The sediment ejected in the form of fine particles is
From 0, it is jetted into the supply path 2 together with hot air, and is supplied to the drying chamber 1 as finer particles by wind pressure. The sediment dried into a powder in the drying chamber 1 is collected in a collecting bag 11.
Collected in. The obtained powder was repeatedly washed and filtered with pure water to elute unreacted NaOH and AlCl ₃ and the reaction product NaCl, and then heat-dried again to obtain 40 g of A.
1-ion crosslinked polymer fine powder was obtained. As a result of microscopic observation, the average particle size of the obtained fine powder was 10 μm.

Here, an example in which the crosslinked polymer is washed after the powder is manufactured is shown. However, before the powder is manufactured, that is, filtration and washing are repeatedly performed in a precipitated state, and then this is sprayed to dry / powder. May be used. Next, 10 x 80 x 60 mm depth
A molding die having a cavity of
g. And 250 ° C while reducing the pressure in the vacuum chamber
And subjected to vacuum heat compression molding at a surface pressure of 3000 to 7000 kg / cm ² for 60 minutes each. The specific gravities of the obtained molded bodies (Sample Nos. A to e) were measured, and the results are shown in Table 1. FIG. 2 shows the results of a three-point bending test performed at room temperature on each molded body and measuring the bending strength. In addition, the thickness of the molded body is about 3 mm. (Comparative Example 1) The precipitate obtained in the same manner as in the example was filtered as it was, washed repeatedly with water and filtration with pure water, and then dried by directly heating it to 150 ° C in a hot air drying oven.

The obtained Al ion crosslinked polymer is strongly agglomerated and cannot be said to be a powder. Then, it was pulverized with a mortar to obtain a powder of about 300 μm. From 4 g of this powder, a compact (sample Nos. F to j) was formed in the same manner as in the example.
Similarly, specific gravity and three-point bending strength were measured. The results are shown in Table 1 and FIG. Comparative Example 2 The powder obtained in Comparative Example 1 was further pulverized in a mortar to obtain a powder having an average particle size of about 30 μm. 4g of this powder
(Example Nos. K to o) were formed in the same manner as in Examples, and the specific gravity and the three-point bending strength were measured in the same manner. Table 1 shows the results
And FIG.

[0020]

[Table 1] (Evaluation) As shown in Table 1, the molded body formed in the example has a high specific gravity and a dense molded body regardless of the pressure during molding. However, in Comparative Example 1, the specific gravity varies greatly due to the pressure at the time of molding because the particle size of the powder is large.
The molded article formed in Comparative Example 2 shows better results than Comparative Example 1, and it can be seen that the same compactness as in the example can be obtained by molding at a pressure of 4000 kg / cm ² or more.

On the other hand, from FIG. 2, the molded body obtained in the example shows a substantially constant high strength regardless of the molding pressure. However, in the molded body obtained in Comparative Example 1, the voids increased at a low molding pressure, and strength was not obtained.
It can be used only at a molding pressure of g / cm ² or more. In Comparative Example 2, the particle size is smaller than that in Comparative Example 1, so that voids are small and high strength is obtained. However, since the Al ion crosslinked polymer was damaged during the pulverization, the strength was lower than that of the example.

That is, according to the Al ion-crosslinked polymer fine powder obtained by the production method of the example, it is apparent that a compact and high-strength compact is formed even when compacted at a low pressure.

[0023]

According to the production method of the present invention, it is possible to easily and reliably produce an extremely fine metal ion-crosslinked polymer fine powder having a substantially spherical shape. There is no risk that the polymer structure will be damaged.
Therefore, by using the metal ion-crosslinked polymer fine powder obtained by the production method of the present invention, it is possible to obtain a dense compact even if the pressure during the heat compression molding is reduced, and to improve the physical properties of the compact. And
Man-hours can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic structural explanatory view of a drying apparatus used in one embodiment of the present invention.

FIG. 2 is a graph showing the relationship between the pressure at the time of molding and the three-point bending strength of the obtained molded body in Examples and Comparative Examples.

[Explanation of symbols]

1: Drying room 2: Supply path 3: Pump 30:
Injection nozzle

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-259818 (JP, A) JP-A-51-31756 (JP, A) JP-A-48-68693 (JP, A) 59006 (JP, A) JP-A-6-16864 (JP, A) JP-A-6-122714 (JP, A) JP-A-1-149805 (JP, A) JP-A-62-74906 (JP, A) JP-A-62-74905 (JP, A) JP-A-6-57034 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C08F 8/44 C08J 3/12-3/16 C08J 3/24

Claims (1)

(57) [Claims] 1. A crosslinkable polymer material reacts with metal ions in an aqueous solution of a hydroxide of at least one of an alkali metal and an alkaline earth metal to react with the metal ions to precipitate a metal ion crosslinked polymer. A method of producing a fine powder of a metal ion-crosslinked polymer, which comprises: a precipitation step of spraying the obtained precipitate of the metal ion-crosslinked polymer in a wet state into fine particles and drying.