JPS604736B2 - Method for manufacturing molded articles from improved inorganic colloids - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing molded articles with improved water resistance and electrical insulation properties by electrochemical treatment.

As inorganic colloidal particles, materials whose crystals form a layered structure, such as naturally occurring minerals such as clay minerals such as kaolin and mowamorillonite group minerals, and highly hydrated alkali ions such as sodium and lithium, are used as inorganic colloid particles. Synthetic minerals such as fluorite, mica, and montmorillonite have the property of forming stable colloids when suspended in a solvent.

Since these colloids have extremely fine particle sizes that are close to molecular, when dried and dehydrated, they exhibit molding performance based on the principle of Van Der Waals' molecular cohesion force. By applying this molding performance, it is possible to manufacture sheet-like objects made of inorganic materials, thick plate-like objects, non-linear irregularly shaped objects, painted materials, etc. In this way, the molded product is useful as it has excellent heat resistance, non-toxicity, and film resistance, but if left as it is, it will reversibly hydrate and swell due to the presence of alkali and its hydration properties, so it will not retain its shape. It has the disadvantage of being inferior in electrical insulation. This is because the above minerals contain alkali ions such as lithium sodium. For example, kaolin group clay minerals adsorb alkali ions because their particle surfaces are negatively charged, and natural montmorillonite and synthetic fluorine Quaternary elementary mica, synthetic montmorillonite, etc. have lithium ions or sodium ions coordinated between the layers to form electrostatic bonds in order to compensate for the lack of charge in their crystal structures, and furthermore, the surface of the elementary particles is negatively charged. It adsorbs alkali ions. These alkali ions enter the solution along with a large amount of hydration water, interposing between the particles and preventing the particles from approaching each other, which causes a stable cloudy state to be maintained in the solvent. Therefore, the presence of such alkali ions has a powerful effect on homogeneous dispersion of these substances in the port, without forming sediments, and produces stable colloids. However, if the above-mentioned alkali ions remain in a molded product obtained by drying and dehydrating these colloids, the molded product will be rehydrated by absorbing moisture from the atmosphere due to the strong hydrating properties of the alkali ions. This phenomenon not only deteriorates water resistance but also increases electrical conductivity, thereby deteriorating insulation properties. For these reasons, it is an extremely effective means to impart water resistance and insulation properties to molded articles by replacing the alkali ions contained in the colloid with other cations that do not rehydrate.

This ion exchange is one of the important basic reactions in chemical reactions, and it progresses based on the principle of the process explained by the redox potential difference and the adsorption sequence of intestinal ions that was elucidated by Hofmeister. It is a reaction to

Conventionally, as a colloid that forms a layered structure with an inorganic substance, the disintegrated bodies of general viscous fine particles such as kaolin group used in the ceramics industry have been well known, but this is because the amount of alkaline added is 1. Since the amount is as small as ~2% and the dried dehydrated product is a ceramic product that is heated at a high temperature to further transform it into a ceramic, there was no need to pay much attention to the above-mentioned hydration properties and insulation properties. However, since natural montmorillonite group minerals, synthetic alkali tetramers, fluorine mica, synthetic montmorillonite, etc. are manufactured by molding methods that involve only drying and dehydration, treatment by ion exchange is essential. Although the object of this invention is mainly based on these three types of layered structures, it is of course also effective to apply to other inorganic minerals containing exchangeable alkali ions. Naturally produced montmorillonite, such as pentonite, has been known as colloidal particles for layered structures, but crystal water ((OH)-) is replaced with F- to create Na or Lj between the layers.
Artificial minerals that coordinate Na (or Li) Mg2.5Si40, oF2, Na (or Li)
M&LiSi40,.

Synthetic fluorine mica as shown by the chemical formula F2, and newly synthesized Li. 33 (or Na.83)
Mg2.67Li. There are synthetic montmorillonites, such as those with the chemical formula 33Si40,oF2, each of which provides an excellent aporous colloid that forms a stable suspension in a solvent. Na shown at the beginning of the above chemical formula
Or Li exists between the layers and is Na08, Lj○,2, or Na. Phantom ○, 2, Li. The spots ○ and 2 have weak electrostatic bonds, and since these Na and Li are not packed and coordinated in the crystal lattice, other cations, namely K,
Ion exchange can be performed with intestinal ions such as 10, Ag10, Cu10, Ba20, Pze+, S〆10, Z desu, N30, Sge10, Bi30, etc.

Since these cations do not have the property of rehydration, the water resistance and electrical insulation properties of the minerals after ion exchange are significantly improved.
The conventional cation exchange method involves preparing an aqueous solution of a salt that dissociates cations from colloidal particles, and storing the solution at room temperature or at about 7,000 ml.
This is done by soaking the food for about 10 hours under heating.

Although such a simple immersion method achieves a certain degree of exchange depending on the type of cation, it has the following drawbacks. The first is related to the hydration properties of these intestinal ions; alkaline elements such as K+ and alkaline elements such as 20 are considerably hydrated in aqueous solutions;
This results in ion exchange with water of hydration, which forms complex bonds between the layers and, in addition to water such as the simple metal hydroxide form, can move up and down between crystalline layers of minerals. It is thought that bound water is formed by coordinating with the oxygen negative charge surface of the hydrogen bond through hydrogen bonds, and water in the hydroxide form is dehydrated by heating to about 300 oo,
Bound water type water cannot be dehydrated unless heated to 550 qo or more.

Heating to such a high temperature may cause the molded product to become ceramic and brittle. second Ag ten,
With metal ions such as Cu+, PM10, Sn20, Zze+, AI30, S10, and Bi30, hydration in the form of bound water as described in the first example above is relatively unlikely to occur, but with the exception of Ag+. When M is a metal and × is a base, MK=Mn++Xn-
There is almost no ionization, but it tends to hydrolyze to produce tsuba ions or precipitates with the constituent elements of the base.

An example of this would be the following chemical formula. ZnC
120 is 20 Zn (OH) 20 squad CIAIC 130 is 20 AI (OH) 30 criminal CIBi (N03) 30 is 2
0ko Bi (OH) 2N03 10 ga N03SKI3 10 thin 20
: If S skin l+ is ion-exchanged with base constituent elements as described above, it will have an adverse effect on the rehydration properties and insulation properties after drying and dehydration.

Therefore, when an acid of the same type as the salt is added to each to prevent hydrolysis, the metal ions dissociate in a hydrated form, as shown in the following example. [Ag(OH2)] 10, [Cu(OH2)4]
20, [Zn (OH2) 6] 20, [Pb (0 ratio) 6]
20, [N(OH2)6] 30, [Bj (XX day 2) 5]
30, [Sb (〇日2)6] 30 The hydrated ions of dissociated metals are effective in ion exchange, but on the other hand, strong acids are produced in relatively large quantities, so this The acid will react with the mineral and attack its composition, defeating the intended purpose. Furthermore, salts with weak acids generally have an extremely low degree of ionization, resulting in poor ion exchange ability. This invention aims to improve the drawbacks of the conventional methods as described above by imparting almost complete water resistance and excellent insulation properties to molded products by an electrochemical method. supplying exchange ions, i.e. metal ions to be exchanged, e.g. Ag+, Cu+, Z〆+, S
High-purity metals that produce metal ions such as n20, Pze+, AI30, S10, Bi30, etc. are used for the cathode and anode, or these metals are used for the anode and graphite for the cathode is used. Exchange ions are supplied using a substance with almost no ionizability. A colloid of the layered structure is injected into an electrolytic cell in which electrodes are arranged facing each other at a concentration of 1 to 5% by weight, and a weakly acidic organic acid such as acetic acid, Hakama acid, formic acid, etc. is added thereto to adjust the pH to 3 to 6. Adjust to the range of

The reason why it is necessary to adjust the pH in this case is that metal ions exist in hydrated form in water, but many of them exhibit amphoteric properties, and are positively charged in acidic conditions and negatively charged in alkaline conditions. Therefore, this invention requires positively charged metal ions, with a pH of 3 to 6.
Each of the metal ions mentioned above exists as an effective positively charged hydrated ion. Each electrode was connected to a DC power source, with a voltage of 100 to 300 V and a current density of l.
Electrolytic operation is performed at owA/~50 skin A/.

Through this operation, metals are eluted by the anode and are supplied into the electrolyte as the above-mentioned hydrated metal ions, and N
a, or the Li ion and the noble redox potential, and the Hoffmeister adsorption order (Li+ is the lowest and then N
and all other ions are in the upper position), and Na or Li is dissociated into Na+ or Li+. Since the pH changes as the electrolytic operation progresses, the operation is continued so that the pH is always maintained in the range of 1 to 6 by adding an organic acid. Inorganic acids HC1, HN03, H2S04
etc. may be used, but care must be taken as the layered structure will be attacked unless the pH is exceeded. In addition, the presence of electrolyte causes the inorganic colloid to coagulate, causing damage inside the tank. In this manner, Na and Li in the colloidal layered structure are almost completely exchanged with metal ions by electrolysis for 30 to 60 minutes. At the end of the operation, the colloid exhibits a loosely dispersed aggregate state similar to a sol. This dispersed aggregate is filtered by suction using a suction waver, and then water is injected from the top of the filter and washed while suctioning.
Na 10 or Li 10 and the added acid are separated and removed from the aggregate. After washing with the cleaning solution until no substances to be removed are detected, the aggregates are added to the water at a content of about 5%, and when vibration is applied using ultrasonic waves (2 Hina C), the aggregates disappear into the water. Since it is dispersed again and exhibits the Tyndall (T skinboard 11) phenomenon to form a colloid, the obtained colloid is used to slowly primary dry a molded product such as a sheet at a drying temperature of room temperature to 10,000 ℃. , 100~300o0
After secondary drying, moisture was almost completely removed, and the insulation resistance showed a value of 5000 MO~. In this way, in this invention, there is no strong acid that would decompose the inorganic layered structure that is a component of the colloid, and the intestinal ions necessary for ion exchange are sufficiently decomposed and supplied, so ion exchange is extremely effective. It's going smoothly. During electrolysis, metal ions are naturally supplied in excess of what is needed for exchange, but even if this excess remains in the molded product, it will dry to form a chemically stable oxide, and such The oxide is not only electrically insulating but also does not rehydrate, so it does not impair the water resistance and insulation properties of the molded product. The thus obtained molded product, such as a film, is a heat-resistant electrically insulating material with improved water resistance.

A further development of this invention is the use of electrodialysis. The chemically resistant electrolytic cell used to carry out this method is divided into three chambers in the order of an anode chamber, a colloid chamber, and a cathode chamber using a mullite ceramic diaphragm having communicating pores that prevent fine particles from passing through. The electrode uses graphite or the same metal as the anode for the cathode, and the same metal as the desired metal ion for the anode. Distilled water is injected into the anode chamber and cathode chamber, respectively, and an aqueous colloid solution having a colloid content of 2 to 5% and adjusted to pH 3 to 5 with an organic acid is injected into the colloid chamber. In the colloid chamber, the fly frame was maintained during the operation, voltage 50-200V, current density 20 skin A/c vertebrae ~ 1
During operation, the anode chamber and cathode chamber are suctioned and drained from one side, and injected from the other. To explain the chemical reaction that occurs in the colloid during this operation, first, hydrated metal ions are eluted from the anode, penetrate the diaphragm, enter the colloid chamber, and are absorbed, creating a layered structure that moves slowly. ion exchange takes place. Since the dissociated N or Li+ has a positive charge, it passes through the diaphragm and is electrically attracted to the cathode. The above is the main ion exchange reaction, but at the same time, dialysis is also a type of electrolytic reaction, so the added organic acid dissociation (day 30) and excess metal ions that did not contribute to ion exchange are transferred to the cathode. They are sucked in and discharged together with waste water.

While adjusting the pH to 3 to 5 by adding an organic acid, until no N or Li+ is detected in the solution in the cathode chamber,
Continue the operation under these conditions. Furthermore, one of the unique phenomena in the above-mentioned electrodialysis is that the distilled water injected into the anode and anode passes through the diaphragm and moves to the anode chamber via the colloid chamber.
Once Nat or Li+ is no longer detected, the pH adjustment is stopped, the current density is limited to about 10-20 A/d, and the operation is continued until the pH value naturally changes to approximately 7.0. At this point, there is no unnecessary N in the colloid chamber.
Almost all of A+ or Li+, organic brewing components, etc. are removed, and colloids that have undergone ion exchange and a certain amount of excess hydrated metal ions are present. In this way, by employing electrodialysis means, the colloid is purified at the same time, and the dried molded product made from this purified colloid raw material has extremely excellent water resistance and electrical insulation properties, as will be described later. Next, examples of this invention will be shown.

Example 1 As an electrode, a graphite square electrode (10 x 7
9.8% or more, 10 x 2 x 150 skin), 250
A: Naturally produced pentonite (Ca content 0.54%, K content 0.06%, Na content 1
．． 56%), B: Sodium chloride, mica (Na content 6
．． 0%), C: Lithium montmorillonite (Li content 4.
1%) containing 3% of each component.

While adjusting the pH of the solution to 2 to 4 with acid, apply direct current to a voltage of 60 to 150 V and a current density of 20 to 100 skin A.
'Ion exchange was performed by applying current under the specified conditions. After the ion exchange was completed, impurities were removed by washing with water to obtain an ion exchanged colloid. Films of 30 ribs x 50 sides with a wall thickness of 0.1 (thickness) were made from this colloid by a pouring and spreading method, and dried at 250:00 to prepare 5 samples each. The average value of the results of the moisture absorption after being left in a humid atmosphere (RH90%) for 1 hour using a chemical balance, the alkaline residue chemically analyzed using a flame colorimeter, etc., and the insulation resistance being measured using a mega tester is It is as follows. Anode By component Alkaline iodine Reabsorption amount Insulation resistance material Data
(MQ) Ag A Na
o. 05 10.9 8000B Na〇,.

8 10,3 CLj 0,05
10,8 Cu A Nao. 08
10.5 5000B Nao. 12 ten
．． 5 5000C Li o. 18 11.1
5000Pb A Nao. 05 11.
5B Na〇,05 10,8 C
+0.8 Zn A
Na o. 15 11.7 5000B
Nao. 15 11.5 5000C Li
o. 18 11.7 5000Sn A
Nao. 14 11.8 5000 anodes by component
Alkali ion Reabsorption amount Insulation resistance material Material Residual amount cooperation (MQ)B Nao. 18 11.8 8000C Li o. 20 11.
9 8000Sb A Nao. 1 11.5 5000B Na0.05 10.7
C Li o. 1 11.0
Bi A Nao. 12 11.5 5
000B Nao. 05 10.8C Li
Example of 〇,1 11,2 2250×200
A mullite ceramic diaphragm plate (40% porosity) with a wall thickness of 7 ribs was installed in the glass tank of the x4 monorail at the low cape position from both ends, tightly attached to the glass wall using chloroprene adhesive.
An electrodialysis apparatus was set up in which the electrodes were arranged at an inter-plane distance of 250 ribs.

Ag, Pb, and Zn were used as anode materials, and electrolysis was performed using the same electrode combination, colloid used, current conditions, and test method as in Example 1. The results are as follows. Anode By component Alkaline iodine Reabsorption amount Insulation resistance material
Data Residual amount (%) (MQ)Ag A
Nao. 06 11.2 8000B
Nao. 1 0.8C Lj.

Claims (1)

[Claims] 1. Inorganic colloidal particles of a hydrated natural or synthetic layered structure mineral having ion exchange ability in which lithium ions or sodium ions are coordinated between the layers or adsorbed on the particle surface, and Ag to be exchanged with the ions. , Cu,
Ion exchange is performed by electrolysis while keeping the inorganic colloid acidic using a metal of the same quality as a metal selected from Zn, Mg, Sn, Pb, Fe, Al, Sb, and Bi as an anode, and then the inorganic colloid is shaped and dried. A method for manufacturing a molded article characterized by: