KR20060086143A - Method of manufacturing water based organic-inorganic hybrid paint - Google Patents

Abstract

The present invention relates to a method for producing an aqueous organic / inorganic composite paint, and more particularly, to a coating container obtained by mixing a potassium silicate and an additive, a sieving pigment, a coloring pigment, and some synthetic resin emulsions in a closed container equipped with a cooling capacitor. And warming to 50 to 80 ° C., and then uniformly stirring the mixture for 3 to 5 hours under nitrogen filling to prepare an aqueous organic / inorganic composite silicate emulsion paint having excellent storage stability and color stability.

Water-based organic / inorganic composite paints * Silicates * Potassium silicate

Description

Method of manufacturing water based organic-inorganic hybrid paints {Method of manufacturing water based organic-inorganic hybrid paint}

The present invention relates to a method for producing an aqueous organic / inorganic composite paint, and more particularly, to a coating container obtained by mixing a potassium silicate and an additive, a sieving pigment, a coloring pigment, and some synthetic resin emulsions in a closed container equipped with a cooling capacitor. And warming to 50 to 80 ° C., and then uniformly stirring the mixture for 3 to 5 hours under nitrogen filling to prepare an aqueous organic / inorganic composite silicate emulsion paint having excellent storage stability and color stability.

As the new house syndrome of new building structures has become a social problem and the flame retardancy of applied materials inside building structures has been rapidly promoted, it is more environmentally friendly and more flame retardant than synthetic resin emulsion paints, which have been used as interior / exterior coatings for concrete building structures. It is urgently needed to supply.

To meet these demands, interior and exterior paints for concrete building structures using inorganic silicates as main binders have been proposed.

Silicate is a composition containing silicon, oxygen atoms and alkali metals and is an environmentally friendly material that is almost natural.

Therefore, the paint composition using inorganic silicate as the main binder is not only environmentally friendly but also has a strong siloxane bond of Si-O-Si. Outstandingly excellent, the cured coating film is integrated by chemical bonding with the surface of concrete material, and the self-curing product forms a porous inorganic coating film, so it has excellent condensation prevention performance, adhesion and breathability.

In addition, various physical properties as paints such as acid resistance and alkali resistance are superior to general synthetic resin paints, and since the pH of the paint itself shows strong alkalinity (pH 12), it is excellent in antibacterial activity.

In addition, the paint composition using silicate as the main binder can neutralize the concrete building structure by removing calcium hydroxide, which is a by-product of hardening of the concrete structure, and carbon dioxide, which is the cause of the neutralization (Scheme 3), in the self-curing process (Scheme 4, 5, 6). Prevent and greatly increase the durability of the structure itself.

※ hardening mechanism of cement

2 (CaO) ₃ SiO ₂ + 6H ₂ O → (CaO) ₃ (SiO ₂ ) (H ₂ O) ₃ + 3Ca (OH) ₂

2 (CaO) ₂ SiO ₂ + 4H ₂ O → (CaO) ₃ (SiO ₂ ) (H ₂ O) ₃ + Ca (OH) ₂

Hardened concrete exhibits strong alkalinity (pH 12-13) due to calcium hydroxide, the hydration product of cement.

※ Neutralization mechanism of concrete

Ca (OH) ₂ + CO ₂ → CaCO ₃ + H ₂ O

The calcium hydroxide produced as a hydration product in the curing mechanism of the cement reacts with carbon dioxide in the air to form calcium carbonate, and the formed calcium carbonate neutralizes the concrete. At this time, the neutralized part does not maintain pH 11, which is required for securing the stability of the passivation film on the surface of the rebar with a pH of 8.5 to 10. Therefore, concrete that has elapsed for a long time generates rust to corrode the steel, thereby increasing the bond strength of the steel. It reduces the moment of resistance by reducing the cross-sectional area of the reinforcement, cracking, peeling, etc. of the coated concrete, thereby reducing the appearance, function and stability of the structure.

※ Curing Mechanism of Potassium Silicate

1) chemical curing by reaction with substances contained in the object

: It is cured by reacting with Ca (OH) ₂ or quartz contained in the coating material when applied to the coating materials such as stone and cement.

K ₂ O × nSiO ₂ + Ca (OH) ₂ → CaO × SiO ₂ + (n-1) SiO ₂ + 2KOH

K ₂ O × nSiO ₂ + mSiO ₂ → K ₂ O × (m + n) SiO ₂

2) Curing by Reaction with CO ₂ in Air

K ₂ O × nSiO ₂ + CO ₂ → K ₂ CO ₃ + nSiO ₂

3) Curing by removing physical moisture due to drying

Thus, attempts have been made to manufacture inorganic silicate paints using various types of silicate binders to produce inorganic silicate paints having various advantages as described above and to apply them as interior / exterior paints of concrete structures.

As a specific example, Korean Patent Laid-Open Publication No. 2000-0017726 discloses a powdered inorganic silicate coating composition using calcium silicate. This is because calcium silicate containing a divalent calcium cation and having a mechanism that is cured by a hydration reaction exhibits excellent initial water resistance without mixing organic synthetic binders, and can produce a nearly natural paint. Have

However, these powder-type paints are relatively poor in the workability of the field, the neutralization of the concrete coating is less effective, it is difficult to color a variety of colors, it is not suitable for the interior / exterior coating of concrete building structures.

Therefore, in order to make up for the disadvantages of the powdered silicate paint, the inorganic silicate paint should also be prepared as a liquid one-component paint like the synthetic resin paint.

In this regard, a method of preparing inorganic silicate paint using lithium silicate, sodium silicate, and potassium silicate, which contains monovalent alkali metal ions and can be produced as a liquid silicate binder, has been studied. Lithium silicate is very expensive and the crack stability of the dry coating film is very high. It is also poorly suited for construction paints, and sodium silicate is suitable for use as a paint binder since sodium carbonate, which is a by-product of hardening, is transferred to the surface of the coating by water contact and recrystallized, resulting in whitening of the surface of the coating. Not.

Potassium silicates, on the other hand, are inexpensive and, unlike sodium silicates, are less likely to be recrystallized by moisture contact, as the byproducts of hardening by-products, are very unlikely to cause whitening of the surface of dry coatings, and even easily occur by rainwater. It is most suitable as the main binder of inorganic silicate paint since it does not significantly alter the appearance of the coating film.

Thus, inorganic silicate paints were mainly prepared using potassium silicate. However, potassium silicates containing monovalent metal ions lose their stability when contacted with divalent or higher metal ions and produce insoluble hardeners that do not redissolve in water and mix raw materials with ester bonds. By hydrolysis, the acid, which is a hydrolysis product, lowers its own pH, resulting in a sharply poor stability.

In addition, as mentioned in the curing mechanism of the potashium silicate, the potashium silicate not only can be cured by reacting with carbon dioxide in the air, but also physically and chemically react with the inorganic raw materials used in the preparation of the paint, thereby increasing the viscosity during storage. This results in poor fluidity and restirrability, and changes the color of colored paints.

Therefore, when preparing the silicate emulsion paint using potassium silicate, it is impossible to use additives having ester bonds with coloring pigments and sieving pigments containing more than two valent metal ions, and the sealant is completely sealed to prevent contact with air. Should be kept.

However, inorganic pigments, especially sieving pigments, used in the manufacture of paints can be selectively used because of the low content of impurities that can affect the stability of potassium silicate, since the natural gemstone itself is ground without pretreatment. It is not possible to use extender pigments from which impurities have been completely removed. As a result, even when optimizing the coloring pigments, extender pigments and additives used in the production of silicate emulsion paints, the paints produced under the influence of impurities mixed in the raw materials cannot be completely prevented from losing stability.

In order to compensate for the problems of the inorganic silicate paint using the potassium silicate, Korean Unexamined Patent Publication No. 2002-0018852 includes a silicate emulsion having improved initial water resistance and storage stability by mixing a potassium silicate with a pigment, an additive, a stabilizer, and a synthetic resin emulsion. Paint compositions are shown.

In other words, the synthetic resin emulsion binder is mixed within the range that does not affect the appearance of inorganic coating properties, thereby compensating for the disadvantages of poor initial water resistance, and improving the stability of the potassium silicate binder by using a pH adjuster as a stabilizer. The shortcomings of the

However, the pH regulators used as stabilizers in the paint compositions presented above also have limitations in stabilizing the complex physico-chemical interactions of potassium silicate and blends, so that the prepared paints increase in viscosity for several days to weeks and provide fluidity and crosslinking of the paints. The reflection tends to become worse.

In addition, there is a fatal problem that the color of the paint is changed during storage when the colored paint is prepared by the introduction of inorganic pigments, this tendency is more poor when stored at 60 ℃ heat than room temperature.

Accordingly, the present inventors have studied to solve the above problems, and can produce an aqueous organic / inorganic composite paint having excellent viscosity stability, flowability, restirrability, and color stability while using potassium silicate and synthetic resin emulsion as main binder compositions. The present invention was found to be complete.

Accordingly, it is an object of the present invention to provide a method for producing an aqueous organic / inorganic composite paint having excellent viscosity stability, flowability, restirrability and color stability while using potassium silicate and a synthetic resin emulsion as main binder compositions.

In order to achieve the above object, the method for producing an aqueous organic / inorganic composite paint of the present invention is a closed container equipped with a cooling condenser for the silicate emulsion coating composition obtained by mixing a potassium silicate and an additive, a sieving pigment, a coloring pigment, and a synthetic resin emulsion. After heating to 50 to 80 ℃ and characterized in that aged for 3 to 5 hours under nitrogen stirring under uniform stirring.

That is, the above object is achieved by eliminating the influence of impurities contained in the raw materials used to prepare the silicate emulsion paint through aging in the manufacturing process.

Hereinafter, the present invention will be described in more detail.

<Production method>

20 to 25% by weight of water and 0.2 to 0.5% by weight of a dispersant are added to the paint production vessel, followed by uniform mixing under low speed stirring. In this case, the dispersant may be polyphosphate, polyacrylate, phosphonate, or the like, and it is preferable to use potassium phosphate to improve the stability of the paint and to secure uniform pigment dispersibility.

0.1-0.3 wt% thickener, 0.5-1.0 wt% stabilizer, and 0.1-0.3 wt% defoaming agent were uniformly mixed in the above uniformly mixed mixture to prepare a dispersion mixture. Here, the thickener may be hydroxy ethyl cellulose, xanthan gum, polyurethane, polyacrylate, vanton, and the like. In view of thickening power, viscosity stability, and delamination stability, a combination of hydroxy ethyl cellulose and xanthan gum is used. desirable.

The antifoaming agent may be mineral oil, silicone emulsion, polysiloxane, etc., but it is preferable to use mineral oil in terms of defoaming force, uniformity of coating film and leveling, and stabilizer is KOH, NH ₄ (OH), TEA, NaOH. In view of stability, it is preferable to use a hydrophilic quaternary ammonium which inhibits self-bonding and aggregation of potassium silicate in hydrophilic quaternary ammonium.

A pigment dispersion paste is prepared by dispersing 10-18% by weight of pigmented pigment (white or colored) and 30-35% by weight of extender pigments under high speed stirring at 2000-2500 rpm in the dispersion mixture prepared above.

At this time, white or colored pigments are used. White pigments can be used regardless of the type of titanium dioxide of rutile type, and colored pigments do not contain divalent or higher metal ions and use inorganic pigments that are not reactive. It is preferred to use an inorganic colored pigment of the iron oxide type, most preferably in terms of storage stability.

As the extender pigment, calcium carbonate, cray, talc, mica, silica, and the like may be used. Combination of calcium carbonate and talc containing no divalent or higher metal ion impurities and dolomite components may be used in terms of storage stability and physical properties of the paint. Most preferred.

When the pigment dispersion is completed, the stirring speed is lowered to 500 ~ 1000rpm, 8 to 10% by weight of the synthetic resin emulsion homogeneously mixed, and then 18 to 25% by weight of the potassium silicate is uniformly mixed to prepare a silicate emulsion paint. The synthetic resin emulsion may be any of polyacrylate emulsion and polystyrene acrylate emulsion as long as it has excellent alkali stability. However, in consideration of the water resistance of the emulsion itself and the water resistance of the final coating, it is preferable to use a polystyrene acrylate emulsion, and the amount thereof is preferably used within 5% of the solid content in terms of the expression of inorganic coating properties.

Potassium silicate has a lower drying and curing rate when the molar ratio (K ₂ O / SiO ₂ ) is less than 3 moles, and poor initial water resistance. Preference is given to using -4 molar potassium silicates.

However, the white and colored silicate emulsion paints prepared above show poor storage stability and color stability of the colored paints due to the influence of impurities remaining in the mixed raw materials despite the optimization of the raw materials as described above.

Accordingly, the object of the present invention can be achieved by the method described below.

The white and colored silicate emulsion paint prepared above is introduced into a closed container equipped with a cooling condenser, a stirrer, and a nitrogen input device, and the closed container is replaced with nitrogen gas. The reason why the inside of the sealed container is replaced with nitrogen gas is that the silicate emulsion paint may be deteriorated by reaction with carbon dioxide in the air during the aging process.

When the preparation is completed as described above, while the silicate emulsion paint is uniformly stirred, the airtight container is gradually warmed and heated to 50-80 ° C., and then the silicate emulsion paint is aged for 3 to 5 hours.

At this time, if the stirring speed is less than 200rpm, the aging efficiency decreases because the paints on the reaction wall are not uniformly mixed due to the lowering of the stirring efficiency, and when the stirring rate is over 1000rpm, a large amount of bubbles are generated in the final manufactured paint, so the stirring speed is 200rpm to 1000rpm. It is desirable to remain.

The reason for raising the aging temperature to 50 ~ 80 ℃ in the aging step is that the stability of the potashium silicate is partially destroyed by the impurities contained in the raw material used to manufacture the paint storage stability for several days to weeks It is to accelerate and remove in advance the manufacturing process that gradually becomes poor and the color of the color paint gradually changes. If the aging temperature exceeds 80 ℃, a large amount of aggregates are formed in the paint due to the stability of the mixed emulsion binder, and if it is below 50 ℃, there is a slight increase in viscosity during storage and the color of the colored paint changes even after aging. do. Therefore, the appropriate ripening temperature for removing the influence of impurities contained in the raw material is 50 ~ 80 ℃, more preferably 60 ~ 70 ℃.

On the other hand, if the aging time exceeds 5 hours, there is no difference in aging according to the increase in time, and if it is less than 3 hours, the aging time is slightly increased during storage because a slight increase in viscosity and color change occur during storage. 3 to 5 hours are preferable.

The white and colored silicate emulsion paints thus prepared exhibit very good viscosity stability, flowability, restirrability and color stability.

Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not limited only to these examples.

Comparative Example 1 Preparation of White Inorganic Silicate Paint

20% by weight of water and 0.3% by weight of potassium phosphate were uniformly mixed at a stirring speed of 1000 rpm, followed by 0.2% by weight of HEC thickener (1%, 25 ° C, 15000-25000 cps), 0.5% by weight of mineral oil and 1.0% by weight of hydrophilic quaternary ammonium. The mixture was uniformly mixed in order to prepare a dispersion.

8 wt% of white pigment (TiO ₂ ), 20 wt% of calcium carbonate, and 20 wt% of talc were added to the prepared dispersion, and the pigment was uniformly dispersed at a stirring speed of 2500 rpm.

After the pigment dispersion was completed, the stirring speed was lowered to 1500rpm, and the white inorganic silicate paint was uniformly mixed in the order of 8% by weight of the synthetic resin emulsion (polystyrene acrylate), 21% by weight of 3.5 mol-potassium silicate and 1.0% by weight of butyl di glycol. Prepared.

[Comparative Examples 2-4] Preparation of Colored Inorganic Silicate Paint

19.7% by weight of water and 0.5% by weight of potassium phosphate were uniformly mixed at a stirring speed of 1000 rpm, followed by 0.3% by weight of HEC thickener (1%, 25 ° C, 15000 to 25000 cps), 0.5% by weight of mineral oil and 1.0% by weight of hydrophilic quaternary ammonium. The mixture was uniformly mixed in order to prepare a dispersion.

10 wt% of black (iron oxide black), red (iron oxide red) and yellow (iron sulfur oxide) pigments were added to the prepared dispersion, and 19 wt% of calcium carbonate and 19 wt% of talc were added to the dispersion paste for each color, and then 2500 rpm. The pigment was uniformly dispersed at a stirring rate of.

After the pigment dispersion was completed, lower the stirring speed of the paint for each color to 1500rpm, and uniformly mixed with 8% by weight of the synthetic resin emulsion (polystyrene acrylate), 21% by weight of 3.5 mol of potassium silicate and 1.0% by weight of butyl di glycol in order. , Red and yellow inorganic silicate paints were prepared.

Example 1

The white silicate emulsion paint prepared in Comparative Example 1 was introduced into a closed container equipped with a cooling condenser, a stirrer, a nitrogen input device, and a thermometer, followed by nitrogen gas to replace the inside of the closed container with nitrogen gas. After the nitrogen gas replacement was completed, the white silicate emulsion paint was gradually stirred to a temperature of 60 ° C. in a closed container using a water bath while uniformly stirring, and the white silicate emulsion paint was aged for 4 hours.

EXAMPLES 2-4

The black, red, and yellow silicate emulsion paints prepared in Comparative Examples 2 to 4 were respectively put in a closed container equipped with a cooling condenser, a stirrer, a nitrogen input device, and a thermometer, and then nitrogen gas was added to replace the inside of the closed container with nitrogen gas. It was. After nitrogen gas substitution is completed, the colored silicate emulsion paints are uniformly stirred, and the temperature of the paints in the airtight container is gradually raised to 60 ° C by using a water bath, and this state is maintained for 4 hours. Aged.

Test Example 1 Comparison of Storage Stability of White Paint

Comparative Example 1, Example 1, and the white synthetic resin emulsion paint (Comparative Example 5, trade name: Startex 1000) were stored for 2 weeks in a constant temperature bath at 60 ° C and evaluated for viscosity stability, flowability, and restirrability. . The results are shown in Table 1 below.

 division Example 1 Comparative Example 1 Comparative Example 5  Viscosity Stability (KU) Right after manufacturing 93KU 86KU 94KU Room temperature 1 week 95 KU 93KU 96KU Room temperature 2 weeks 95 KU 98KU 96KU 60 ℃ 1 week 94KU 109KU 96KU 60 ℃ 2 weeks 95 KU 104KU 95 KU  liquidity Room temperature 1 week ○ ○ ○ Room temperature 2 weeks ○ △ ○ 60 ℃ 1 week ○ × ○ 60 ℃ 2 weeks ○ × ○  Restirrability Room temperature 1 week ○ ○ ○ Room temperature 2 weeks ○ ○ ○ 60 ℃ 1 week ○ × ○ 60 ℃ 2 weeks ○ × ○

(○: Excellent, △: Normal, ×: Poor)

Test Example 2 Comparison of Storage Stability and Color Stability of Colored Paints

Comparative Examples 2 to 4, Examples 2 to 4, and colored resin (black, red, yellow) synthetic resin emulsion paints (Comparative Examples 6 to 8, trade name: Acrotex A) were used at room temperature and 60 ° C. for 2 weeks, respectively. Storage was compared to evaluate viscosity stability, flowability, restirrability and color stability. The results are shown in Table 2 below.

division black Red yellow Example 2 Comparative Example 2 Comparative Example 6 Example 3 Comparative Example 3 Comparative Example 7 Example 4 Comparative Example 4 Comparative Example 8  Viscosity Stability (KU) Right after manufacturing 97KU 95 KU 94KU 96KU 93KU 95 KU 100 KU 97KU 97KU Room temperature 1 week 99KU 102KU 94KU 99KU 100 KU 96KU 100 KU 102KU 97KU Room temperature 2 weeks 99KU 105 KU 94KU 99KU 103KU 97KU 104KU 105 KU 97KU 60 ℃ 1 week 101KU 119KU 95 KU 102KU 117 KU 98KU 106KU 122KU 95 KU 60 ℃ 2 weeks 100 KU 115 KU 94KU 101KU 113 KU 97KU 104KU 119KU 96KU  liquidity Room temperature 1 week ○ △ ○ ○ ○ ○ ○ × ○ Room temperature 2 weeks ○ × ○ ○ △ ○ ○ × ○ 60 ℃ 1 week ○ × ○ ○ × ○ ○ × ○ 60 ℃ 2 weeks ○ × ○ ○ × ○ ○ × ○  Restirrability Room temperature 1 week ○ ○ ○ ○ ○ ○ ○ △ ○ Room temperature 2 weeks ○ △ ○ ○ ○ ○ ○ × ○ 60 ℃ 1 week ○ × ○ ○ × ○ ○ × ○ 60 ℃ 2 weeks ○ × ○ ○ × ○ ○ × ○ Color Stability (△ E): Minolta Room temperature 1 week 0.32 1.09 0.10 0.12 0.37 0.26 0.28 0.83 0.20 Room temperature 2 weeks 0.26 0.96 0.16 0.29 0.77 0.30 0.38 1.59 0.18 60 ℃ 1 week 0.54 2.98 0.36 0.38 1.58 0.42 0.54 2.62 0.40 60 ℃ 2 weeks 0.38 4.16 0.34 0.48 2.05 0.38 0.57 3.19 0.43

(○: Excellent, △: Normal, ×: Poor)

As described above, the present invention is a useful invention that provides a process for producing an aqueous organic / inorganic composite paint which can greatly improve the viscosity stability, flowability, restirrability and color stability of the silicate emulsion paint.

In particular, the present invention is a breakthrough invention that enables the widespread application of silicate emulsion paints in a wide range of fields by solving problems of poor storage stability and color stability, which have been pointed out as fatal disadvantages of silicate emulsion paints. .

Claims (2)

In the method for producing an aqueous organic / inorganic composite paint, the silicate emulsion coating composition obtained by mixing a potassium silicate, an additive, an extender pigment, a coloring pigment, and a synthetic resin emulsion is introduced into a closed container equipped with a cooling condenser, a thermometer, and a nitrogen injector. Method of producing an aqueous organic / inorganic composite coating, characterized in that the mixture is heated under uniform stirring and aged for 3 to 5 hours under nitrogen filling. The method of claim 1, wherein the heated aging temperature is 50 ~ 80 ℃.