JPS6343965A - Non-precipitating silica composition for coating and production thereof - Google Patents

Abstract

PURPOSE:To obtain the title compsn. for coating, which is inexpensive and has a long pot life and excellent applicability etc., by removing most of an alkali from an aq. soln. of an alkali metal silicate, adding a growth inhibitor thereto and dispersing the mixture in a diluent. CONSTITUTION:0.1-7wt% (in terms of silica) aq. soln. of an alkali metal silicate (e.g., an aq. soln. of sodium silicate) is brought into contact with a hydrogen type cation exchange resin at 0-35 deg.C to remove most of the alkali. A growth inhibitor (e.g., ethylene glycol, N-methyl-2-pyrrolidone) is added to the resulting non-precipitating silica dispersion. The growth inhibitor must be used in an amount of at least 0.5mol per mol of the non-precipitating silica component. After most of water is removed or without removing water, the mixture is dispersed in a diluent (e.g., methanol, n-propanol) to obtain the title silica compsn.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a non-sedimentable silica composition for coating that forms a transparent, hard coating with good adhesion on a substrate, and a method for producing the same.

[Conventional technology]

BACKGROUND ART Various methods have been used to form a film by coating an inorganic oxide on a base material such as plastic, glass, ceramic, or metal. The coating has functions such as unique electrical properties, optical properties, chemical properties, or mechanical properties due to the metal elements in the film. It is used in a wide range of fields including the electronics field and the optical equipment field, such as visible light non-reflective films, infrared reflective films, ultraviolet absorbing films, and mechanical aerosol preservation films.

Among them, methods for forming transparent films with hard coating properties include thermal decomposition methods, alkoxide hydrolysis methods, sol-gel methods, and melting methods.
In the melting method, the base materials that can be used are limited by the heat resistance of the base material; in the alkoxide hydrolysis method, the alkoxide hydrolysis conditions (degree, humidity, coating speed, etc.) The properties of the film are influenced by the balance of the gel and other factors. Furthermore, all of these raw materials were expensive. There are other coating liquids whose main component is alkali silicate, such as water glass, but they contain a large amount of alkali (cations) and are therefore limited in their use. In addition, the silicic acid solution obtained by removing cations from an alkali silicate produces not only silicic acid but also colloidal particles that are polymerized at the same time, and is extremely unstable and tends to gel in a short period of time. Therefore, it was never used as a coating liquid. Furthermore, the properties of the film are generally influenced by the coating method.
Furthermore, the coating liquid used in the coating method is easily affected by the surrounding environment and has poor storage stability, and most of them have a short pot life (usable period of about one blade).

[Problem that the invention seeks to solve]

The present invention solves the problems associated with the prior art as described above,
A non-precipitating silica composition for coating that is inexpensive, can be easily applied regardless of the shape of the substrate, can be stored for a long period of time, and can form a transparent, hard coating film with good adhesion, and its production. It seeks to provide law.

[Means for solving problems]

The present invention is capable of converting most alkalis (
In the non-precipitating silica aqueous solution obtained by removing cations),
A coating composition and an inorganic binder composition are obtained in which non-sedimentable silica in the liquid is stabilized by adding a specific growth inhibitor.

The coating composition and method for producing the same according to the present invention will be specifically explained below. The bedding alkali according to the present invention is water-soluble such as lithium silicate, sodium silicate, potassium silicate, and quaternary ammonium silicate, and these can be used in combination or in combination. Furthermore, Si (% 7M20 (mol/mo
l ), when M is Na, α5 to 4, when M is K, it is 1 to 4, and when M is Ll, it is 2 to 9, and the quaternary ammonium silicate is ゛, X (NRI R2R3R4
)20YSiO*・ZH20, X-1, Y=α
5-20, z=0-99, R1-4: Hydrogen or an alkyl group or alkoxy group having 1 to 20 carbon atoms. Non-precipitating silica can be obtained from this aqueous alkali silicate solution by exchanging the alkali and hydrogen in the aqueous alkali silicate solution. As the method, a known method such as an ion exchange method or a dialysis method can be used.

The non-sedimentable silica according to the present invention is obtained by the above-mentioned method, and the 8102 conversion temperature in the alkaline silicate water bath is adjusted to 111 to 7 wt%, and the heating temperature is adjusted to 0 to 35°C.

More preferably, the arrangement should be within the range shown in Figure 1. 8wt
% or higher than 35° C., gelation may occur during the alkali and hydrogen t-exchange, or a large amount of colloidal particles will be produced. Further, if the temperature is below 0°C, the ion exchange rate is slow, so it is not industrially practical, and furthermore, if it is below the freezing point, it will gel. The alkali remaining in the liquid is Si
O*/M20 (mob/mol) is (M=Li.

Na, K, NRIR2R3R4) 200 or more, preferably 1000 or more, and preferably 10000 or more in nests. If it is less than 200, the growth inhibitor will have no effect and the liquid will gel in a short time at room temperature.

The non-precipitating silica referred to here is 2-0 wt% (81
0° conversion) water soluble g, 250. QOOG, when centrifuged for 1 hour, the precipitate is 30 parts by weight or less, preferably 0 parts by weight or less, based on the total Sin in the aqueous solution. Since the non-precipitated silica thus obtained is unstable and easily undergoes gelatinization in which colloidal particles are produced, a growth inhibitor is added to stabilize the non-precipitated silica. Non-precipitating silica is stabilized by growth inhibitors because the hydroxyl groups of non-precipitating silica form hydrogen bonds with the functional groups of the growth inhibitor, which prevents the hydroxyl groups of non-precipitating silica from coming into contact with each other. It is presumed that this is because of this.

Therefore, the growth inhibitor according to the present invention may be a hydrophilic organic solvent or a water-soluble crystal that has a functional group that forms a hydrogen bond with the hydroxyl group of non-precipitating silica, and ψrie is ethylene glycol, globylene glycol. , glycols such as ethylene glycol methyl ether and their monoether/monoester derivatives, aliphatic amines such as amylamine and ethanolamine, formamide, N, N-
Derivatives thereof such as dimethylformamide, lactones and derivatives thereof such as butyrolactone, r-valerolactone, r-caprolactone, morpholine and derivatives thereof, 2-pyrrolidone and derivatives thereof, dimethyl sulfoxide and derivatives thereof, and one or more thereof. The above can be used in combination. The growth inhibitor is non-sedimentable Sin in the liquid, component 1! It is sufficient if it is at least 15m01 for 1101. (If it is less than 15m01, the stability of the non-precipitated silica component will deteriorate.Increasing the use of the growth inhibitor will not bring any disadvantages to the present invention.Dilute this stabilized non-precipitated silica component. When dispersed in a solution, a non-sedimentable, precipitated silica'Bi composition for coating of the present invention can be obtained. Depending on the base material, moisture may affect the film and molded product (retention property, adhesion, etc.). Dehydration may be carried out before adding the diluent as this causes a strong reaction.For dehydration, known methods such as distillation and ultra-dehydration can be used.In this case, non-sedimentation occurs unless the temperature is below 90°C. The stability of silica deteriorates, and colloidal particle formation or growth and gelation occur.

The composition ratio of the non-precipitating silica fraction, water, and growth inhibitor according to the present invention is the above (growth inhibitor/non-precipitating silica component)≧
After satisfying the conditions of 05, the non-sedimentable silica component is α5 to 25 wt%, preferably 15 to 1
5 wt%, moisture is α1~? ? , 3 wt%, and the growth inhibitor is preferably 12% and 99.4 wt%. If the non-sedimentable silica component exceeds 15 wt%, the stability of the solution will be shortened.
If it exceeds 25 wt%, it becomes even shorter and gels easily. If the growth inhibitor is less than α2 wt%, it becomes ineffective and the non-sedimentable silica component tends to gel.

The diluent for dispersing these three components may be one that does not affect the non-sedimented silica component ◇ The dilution ratio or the diluent may be adjusted according to the coating method, for example Six examples to choose from, for example, methanol,
Ethanol, n-propanol, 1-glopanol,
Alcohols such as n-butanol, 1-butanol and t-butanol, acid esters such as methyl acetate and ethyl acetate, ethers such as diethyl ether, and acetone can be used alone or in combination.

The ff1g product for coating of the present invention can be prepared using a spinner method.
Coating can be performed by a known method such as a spray method, dip method, bar code method, roll coating method, or printed method. After coating, it may be baked at a temperature at which the diluent, water, and growth inhibitor in the composition evaporate or decompose.

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

〔Example〕

Example 1 810, 5 wt% sodium silicate water bath solution (5 wt%)
iOz/Nano” 3-mol/mol, ) 4
A non-sedimentable silica solution (1) was obtained by passing it through a cation exchange resin column maintained at 800't f-15°C for 1 hour at a space velocity of 5V=S. After adding 44 g of ethylene glycol to 100 t of this liquid and sufficiently dispersing it, the mixture was heated to 70°C under reduced pressure using a rotary evaporator to distill off 94 f of water. (Dispersion liquid 1) This liquid was cooled and 200 l of ethanol was added to obtain a coating liquid.

Example 2 100t of the non-sedimentable silica liquid obtained in Example 1
27f of vcN-methyl-2-pyrrolidone was added and thoroughly dispersed. (Dispersion liquid...) To this liquid, 123 f methanol/n-butanol (weight ratio 1/1) was added to obtain a coating liquid.

Example 3 Sin, α5 vt% sodium silicate aqueous solution (
810x/Nano” 3 moVmob) 24
0 f was maintained at 25° C. and passed through a cation conversion resin column at a space velocity of 8 V=2 to obtain a non-sedimentable silica solution. After adding 9 tons of 100 fvc N-methyl-2-pyrrolidone to this liquid and thoroughly dispersing it, the water was heated to 70°C under reduced pressure using a rotary evaporator to dissolve 9 tons of water.
I made 92 Tomita. (Dispersion ■) Cool this liquid and add 10% ethanol to it. A coating liquid was obtained.

Example 4 A 7 wt% sodium silicate aqueous solution (5 wt%) was used as Sill.
iO1/Na1O= 3 mob/ mob) 20
0 f was maintained at 15° C. and passed through a cation exchange resin column at a space velocity of 5 V=6 to obtain a non-sedimentable silica solution. 600 t of N-methyl-2-pyrrolidone was added to 100 t of this liquid and sufficiently dispersed.

(Dispersion liquid ①) To this liquid, 700 g of methanol/n-butanol (weight ratio 1/1) was added to obtain a coating liquid.

Example 5 Sin, S wt% sodium silicate aqueous solution (8
101/Na1O= 5 mob/mob) 200
While f was maintained at 2°C, it was passed through a cation exchange resin column at a space velocity of 5V=4 to obtain non-precipitated silica t'.

Of this liquid, 100f contains 1 N-methyl-2-pyrrolidone.
After adding 49f and thoroughly dispersing it, heat it to 70°C while reducing the pressure in a rotary evaporator to reduce the water to 949f.
9 distillates were distilled out. (Dispersion ■) This liquid was cooled and further 802 ml of ethanol was added to obtain a coating liquid.

Example 6 Sin, 6 wt% sodium silicate aqueous solution (5
iO1/Na1O= 5 moVmol)
A non-sedimentable silica solution was obtained by passing through a cation conversion resin column at a space velocity of 5 V=a while maintaining the temperature at 200 ft-25°C. 100t of this liquid
900 t of N-methyl-2-pyrrolidone was added to the solution and thoroughly dispersed.

(Dispersion ff1Vl) 10001F of methanol/n-butanol (weight ratio 1/1) was added to this liquid to obtain a coating liquid.

Example 7 S10! 5 wt% potassium silicate aqueous solution (Si
O1/10=4 mob/mol) 200 f
f It was maintained at 15° C. and passed through a cation exchange resin column at a space velocity Hsv=s to obtain a non-sedimentable silica solution.

After adding 600 f'i of ethylene glycol monoethyl ether to 100 tons of this liquid and thoroughly dispersing it, an ultrafiltration membrane (Asahi Kasei g, 5IP-5013, 15℃, ΔP
Water f913 was distilled out using t-t (dispersion liquid Vl). This liquid was cooled and further ethanol t-300f was added to obtain a coating liquid.

Example 8 Sin, S wt% tetraethylammonium silicate aqueous solution ((N(C2H5)4-20・I A
3810. ) 200t was passed through a cation exchange resin column at a space velocity of SV=S while being maintained at 15°C to obtain a non-sedimentable silica solution. Example 1 except that morpholine 441 was added to 1002 of this liquid and sufficiently dispersed.
A coating solution was obtained under the same conditions as Example 9. Non-sedimentable silica solution obtained in Example 1 (10 out of 1
N-methyl-2-pyrrolidone 5 at 0f? After adding and sufficiently dispersing, the rotor was heated to 70°C while reducing the pressure using a borator to distill off 55f of water (Dispersion IX). This liquid was cooled and further mixed with methanol/n-butanol. A coating liquid was obtained by adding 200f of (true weight ratio 1/1).

Example 10 10 of the non-sedimentable silica liquid (1) obtained in Example 1
After adding N-methyl-2-pyrrolidone 209 to 0g and sufficiently dispersing it, the mixture was heated to 70°C under reduced pressure using a rotary evaporator to distill off 70f of water. (Dispersion fiX) This liquid was cooled and further t-20 of ethanol/n-butanol (weight ratio 1/1) was added to obtain a coating liquid.

Example 11 Sin, 5 wt% sodium silicate aqueous solution (8
107 Na! O = 5 noVmob ) 4 B O
f f It was passed through a cation conversion resin column at a space velocity of 8V=15 while being maintained at 5°C to obtain a non-sedimentable silica solution. Of this liquid, 100f KN-methyl-2-pyrrolidone/ethylene glycol (weight ratio 1/1) 150f
i was added and sufficiently dispersed. (Dispersion fiXl) To this liquid, ethanol'i250f was added to obtain a coating liquid.
iO1/Na1O= 5 mol/In01) 4
While keeping B Of at IOC, it was passed through a cation conversion resin column at a space velocity of 8 V = 10 to remove non-sedimentable silica. 100 f of this solution was added with 7150 f of KN-methyl-2-pyrrolid to sufficiently disperse it. (Dispersion XI
) A coating liquid was obtained under the same conditions as in Example 11 except for the following conditions.

Comparative Example 1 As S101, 5 wt thli-acid sodium aqueous solution (5ins/Nano” 5 mob/mo
x) 480 f was passed through a cation conversion resin column at a space velocity of 8V=10 while being maintained at 5°C to obtain a non-sedimentable silica solution. Of this liquid, 100 fKN -)
A well-dispersed force ζ dispersion with 400 ft of lfpw-2-pyrrolidone gelled in a few minutes.

Comparative Example 2 10 of the non-precipitating silica liquid (l) obtained in Example 1
15Of ethanol was added to 01 and sufficiently dispersed to obtain a coating liquid.

Comparative Example 3 10 of the non-precipitating silica liquid (1) obtained in Example 1
After adding 72.5f of 00fKN-methyl-2-pyrrolidone and sufficiently dispersing it, it was heated to 70°C under reduced pressure using a rotary evaporator to distill out 947.5f of water, but the dispersion was dissolved in a few minutes. It became a group.

Results t-*-1 Coating film test Using the coating liquids obtained in the Examples and Comparative Examples above, coating films were obtained using the following substrates, coating methods, and drying/baking conditions. The resulting coating film was evaluated for appearance, adhesion, and film hardness.

■ Substrate: PET film, acrylic board, glass board,
Aluminum plate, (shape, 103× ■ Coating method: spinner method (2000r, p, m,),
Barcode method (bars are for φOt) ■ 8 drying/baking conditions: PIT film/acrylic plate: 110°C @ 20 minutes. The glass plate and aluminum plate were dried at 110°C for 1 hour and then fired at 200°C for 1 hour.

Evaluation method〉 ■ ``The presence or absence of mottling or cracks on the membrane was observed with a second glance, and those with even one spot were given a ×, and those with none were given a score of O. ■ Transparency: Total line transmittance ( Dust and haze (6) were measured using a haze condenser (behind the scar tester).

■ Adhesion: Measured using the JI8DO202-71 substrate test.

In this test, the paint film was cut into 100 pieces at 1-interval intervals with a utility knife, a part of commercially available cellophane tape with a width of 12 strips was attached, the remaining part was kept perpendicular to the paint film, and the film was instantly peeled off and placed on the board. The number of remaining sections was counted. ■Hardness: Both sides passed the JIS DO202-71 pencil hardness test.

In this test, a commercially available pencil was pressed against the paint film at an angle of 45°, and scratches on the paint film were visually observed by pressing the pencil.

Result 1! : Shown in Table-2.

Table-2 Not yet.

〔Effect of the invention〕

The non-precipitating silica composition for coating according to the present invention includes:
Most alkalis (cations) from silicate alkali aqueous solution
A specific growth inhibitor is added to the non-sedimenting silica aqueous solution obtained by T-removal to stabilize the non-sedimenting silica in the solution, making it an inexpensive and long pot life (3 months or more at room temperature) base. It can be easily applied regardless of the shape of the material.

Furthermore, by applying the coating composition of the present invention to plastic, glass, ceramic, and gold 461, it is possible to easily obtain a coating film having a transparent node coat with good sealability at low temperatures. can. Furthermore, the present invention can be used as an inorganic binder composition, and new functions can be imparted to the coating film by mixing inorganic or organic metal salts, colloidal particles, inorganic fibers, tabular particles, etc. For example, if 5nC14, 5bC15, or InCl3 is mixed in, a coating film with electrical conductivity can be obtained, and if colloidal particles of titanium oxide are mixed in, a coating film with an ultraviolet reflection function can be obtained.

[Brief explanation of drawings]

FIG. 1 is a graph showing preferred conditions for producing non-precipitating silica.

Claims (7)

[Claims] (1) A non-precipitating silica composition for coating, characterized in that a growth inhibitor is added to a non-precipitating silica dispersion obtained by removing most of the alkali from an aqueous alkali silicate solution, and this is dispersed in a diluent. (2) The growth inhibitor is ethylene glycol, N-methyl-
The non-precipitating silica composition for coating according to claim 1, which is one or more of 2-pyrrolidone, morpholine, and ethylene glycol monoethyl ether. (3) The non-precipitating silica composition for coating according to claim 1 or 2, wherein the growth inhibitor is present in an amount of at least 0.5 mol per 1 mol of the non-precipitating silica component. (4) Residual alkali is 200% for SiO_2/M_2O
The non-sedimentable silica composition for coating according to claim 1, 2 or 3, which has a molecular weight of at least 1,000, preferably at least 1,000. (5) After bringing an aqueous silicate aqueous solution into contact with a hydrogen-type cation exchange resin to remove most of the alkali, a growth inhibitor is added, and then most of the water is removed, or a diluent is added without removing it. A method for producing a non-sedimentable silica composition for coating, characterized in that it is added and dispersed. (6) The growth inhibitor is ethylene glycol, N-methyl-
6. The manufacturing method according to claim 5, wherein one or more of 2-pyrrolidone, morpholine, and ethylene glycol monoethyl ether are used. (7) Silica equivalent concentration in aqueous alkali silicate solution is 0.1
7% by weight, and the ion exchange treatment temperature is 0 to 35°C.