KR102627256B1 - CaO And Lime-based water-based exterior paint Using Oyster Shell And Manufacturing Method Thereof - Google Patents

Abstract

The present invention develops and commercializes an eco-friendly lime-based water-based exterior paint by recycling oyster shells. By using oyster shells, which are marine waste, as the main raw material of the eco-friendly paint, it is easy to secure resources, creates added value, and improves the local economy by creating new demand. Activation has the advantage of solving various problems.

Description

Quicklime manufactured using oyster shell, lime-based water-based exterior paint and manufacturing method thereof {CaO And Lime-based water-based exterior paint Using Oyster Shell And Manufacturing Method Thereof}

The present invention relates to quicklime manufactured using oyster shells, lime-based water-based exterior paint, and a method for producing the same.

As oyster production increases, the number of oyster shells is increasing. 50% of oyster shells are recycled for oyster seedlings, 10% are recycled as fertilizers and industrial raw materials, and the remaining 40% are discarded. Oyster shells that need to be disposed of are classified as industrial waste and can only be transported by transport vehicle. They have to be processed by a qualified processor or by consignment, which is expensive and inconvenient, so they are left on the coast. Oyster shells left illegally on the coast not only damage the aesthetics, but also interfere with fishermen's fishing activities and have a negative impact on the local tourism industry.

Oyster shells are mainly composed of calcium carbonate (CaCO ₃ ), so they have similar properties to limestone. Therefore, if oyster shells can be recycled into lime-based products, it is expected that the recyclability of oyster shells can be improved, thereby reducing oyster shell processing costs and creating new added value.

Quicklime (CaO) can be produced by calcining calcium carbonate (CaCO ₃ ), and lime-based paint can be produced by hydrating quicklime to produce slaked lime (Ca(OH) ₂ ).

Japanese Patent Publication No. 2001-187867 discloses a coating composition containing slaked lime, a copolymer component, and water that satisfies the requirements of JIS K 5663-1995; Japanese Published Patent No. 2003-292898 contains 30 to 70% by weight of slaked lime, 2 to 50% by weight of organic resin binder, 2 to 40% by weight of antifoaming agent, 2 to 30% by weight of calcium silicate hydrate, and 40 to 90% by weight of water. A coating composition comprising; Japanese patent publication 2004-307259 discloses a slaked lime-based ceramic composition containing calcium hydroxide (Ca(OH) ₂ ) or a mixture of calcium hydroxide (Ca(OH) ₂ ) and magnesium hydroxide (Mg(OH) ₂ ) and urastonite. It has been invented.

However, the slaked lime used in the above patent is slaked lime manufactured using high-purity quicklime produced from high-quality limestone. Quicklime manufactured from low-quality materials such as low-quality limestone, which is expensive due to its high impurity content, or oyster shells, which are discarded waste products, produces low-quality slaked lime due to its high content of impurities. Therefore, when lime-based paint is produced using low-quality limestone or oyster shell, the fluidity and color of the paint do not meet the quality standards of commercial products due to the impurities, so there are restrictions on the production of lime-based paint products through recycling. .

Patent documents and references mentioned herein are herein incorporated by reference to the same extent as if each individual document was individually and specifically identified by reference.

Japanese public patent 2001-187867 Japanese public patent 2003-292898 Japanese Patent 2004-307259

The purpose of the present invention is to produce high-quality quicklime and slaked lime using discarded oyster shells, and to provide a lime-based water-based exterior paint manufactured using the same and a method for producing the same.

Other objects and technical features of the present invention are presented in more detail by the following detailed description, claims, and drawings.

The present invention includes a first step of washing oyster shells and then producing oyster shell fine powder with an average particle size of less than 50㎛; And a second step of producing a quicklime (CaO) mixture by calcining the oyster shell fine powder at 1,100 to 1,200°C for 2 hours and 30 minutes to 3 hours and 30 minutes.

The oyster shell fine powder is characterized in that the CaO content is 50 to 53 wt%, the calcining has a calcination rate of 99 to 99.9%, and the quicklime mixture prepared through the calcining has a quicklime (CaO) content of 98.5 to 99.9%. It is characterized by 99.9wt%.

The present invention includes a first step of washing oyster shells and then producing oyster shell fine powder with an average particle size of less than 50㎛; A second step of producing a quicklime (CaO) mixture by calcining the oyster shell fine powder at 1,100 to 1,200°C for 2 hours and 30 minutes to 3 hours and 30 minutes; A third step of preparing a quicklime suspension by mixing the quicklime mixture and water at a weight ratio of 1:1.5 to 2.5 and performing a hydration reaction for 25 to 30 minutes to prepare a slaked lime (Ca(OH) ₂ ) mixture; A fourth step of preparing a thickener solution by adding 7 to 8 parts by weight of a thickener based on 100 parts by weight of water; A fifth step of preparing a thickener-defoamer solution by adding 0.5 to 1.5 parts by weight of an anti-foaming agent to the thickener solution based on 100 parts by weight of the water; A sixth step of preparing a slaked lime suspension by adding 30 to 40 parts by weight of slaked lime mixture, 11 to 15 parts by weight of white pigment, and 6 to 8 parts by weight of crystalline dolomite to the thickener-defoaming agent solution based on 100 parts by weight of water; A seventh step of preparing a slaked lime dispersion suspension by adding 0.5 to 1.5 parts by weight of a dispersant based on 100 parts by weight of water to the slaked lime suspension; and an eighth step of preparing a lime-based water-based exterior paint by adding 30 to 40 parts by weight of an acrylic resin to the slaked lime dispersion suspension based on 100 parts by weight of water. Provides a manufacturing method for exterior paint.

The oyster shell fine powder is characterized by a CaO content of 50 to 53 wt%. The calcining has a calcination rate of 99 to 99.9%, and the quicklime mixture prepared through the calcining has a quicklime (CaO) content of 98.5 to 99.9wt%. The slaked lime mixture is characterized in that it contains calcium hydroxide (Ca(OH) ₂ ) and calcium carbonate (CaCO ₃ ) as calcium components in a weight ratio of 96.5 to 97.5:2.5 to 3.5, and is a lime-based aqueous external product prepared by the production method of the present invention. The paint is characterized by meeting the KS water-based exterior paint type 1, grade 2 standards.

The present invention develops and commercializes an eco-friendly lime-based water-based exterior paint by recycling oyster shells. By using oyster shells, which are marine waste, as the main raw material of the eco-friendly paint, it is easy to secure resources, creates added value, and improves the local economy by creating new demand. Activation has the advantage of solving various problems.

Figure 1 shows the results of XRD analysis of the crystal structure of the oyster shell fine powder with an average particle size of 74㎛ or less and the oyster shell fine powder with an average particle size of 45㎛ or less of the present invention. Panel (a) is for oyster shell fine powder with an average particle size of 74㎛ or less, and panel (b) is for oyster shell fine powder with an average particle size of 45㎛ or less.
Figure 2 shows the results of TG-DSC analysis of the thermal decomposition (decarboxylation) characteristics of the oyster shell fine powder with an average particle size of 74 ㎛ or less and the oyster shell fine powder with an average particle size of 45 ㎛ or less of the present invention. Panel (a) is for oyster shell fine powder with an average particle size of 74㎛ or less, and panel (b) is for oyster shell fine powder with an average particle size of 45㎛ or less.
Figure 3 shows the XRD change and crystal phase according to the holding time for each firing temperature in an electric furnace for the oyster shell fine powder with an average particle size of 45㎛ or less of the present invention. Panel (a) is the result for the firing condition 950℃/1 hour, panel (b) is the result for the firing condition 1050℃/1 hour, and panel (c) is the result for the firing condition 1150℃/1 hour, and panel ( d) is the result for the firing condition of 1150℃/2 hours, and panel (e) is the result for the firing condition of 1150℃/3 hours.
Figure 4 shows the temperature change results of the ASTM C 110 test according to the CaO/water mixing conditions of the present invention. Panel (a) is the result for the CaO/water 1:4 mixing condition, and panel (b) is the result for the CaO/water 1:2 mixing condition.
Figure 5 shows the XRD analysis results of the hydration reactant prepared by the ASTM C 110 test according to the CaO/water mixing conditions of the present invention. Panel (a) is the result for the CaO/water 1:4 mixing condition, and panel (b) is the result for the CaO/water 1:2 mixing condition.
Figure 6 shows the SEM analysis results of the hydration reactant prepared by the ASTM C 110 test according to the CaO/water mixing conditions of the present invention. Panel (a) is the result for the CaO/water 1:4 mixing condition, and panel (b) is the result for the CaO/water 1:2 mixing condition.

The present invention includes a first step of washing oyster shells and then producing oyster shell fine powder with an average particle size of less than 50㎛; and a second step of producing a quicklime (CaO) mixture by calcining the oyster shell fine powder at 1,100 to 1,200°C for 2 hours and 30 minutes to 3 hours and 30 minutes.

The main component of the oyster shell is calcium carbonate (CaCO ₃ ), and when the oyster shell is crushed and made into fine powder, the CaO content increases and impurities decrease. According to an embodiment of the present invention, the oyster shell fine powder is characterized in that the CaO content is 50 to 53 wt%. If the average particle size of the fine powder produced by grinding the oyster shell exceeds 50㎛, the content of impurities other than calcium increases, and the calcium content of the quicklime and slaked lime produced thereafter decreases, causing a problem in that the quality deteriorates.

In the present invention, quicklime (CaO) mixture is prepared by calcining the oyster shell fine powder at 1,100 to 1,200°C for 2 hours and 30 minutes to 3 hours and 30 minutes. The calcination rate of the calcination is 99 to 99.9%, and the quicklime mixture prepared through the calcination is characterized in that the quicklime (CaO) content is 98.5 to 99.9wt%.

The present invention includes a first step of washing oyster shells and then producing oyster shell fine powder with an average particle size of less than 50㎛; A second step of producing a quicklime (CaO) mixture by calcining the oyster shell fine powder at 1,100 to 1,200°C for 2 hours and 30 minutes to 3 hours and 30 minutes; A third step of preparing a quicklime suspension by mixing the quicklime mixture and water at a weight ratio of 1:1.5 to 2.5 and performing a hydration reaction for 25 to 30 minutes to prepare a slaked lime (Ca(OH) ₂ ) mixture; A fourth step of preparing a thickener solution by adding 7 to 8 parts by weight of a thickener based on 100 parts by weight of water; A fifth step of preparing a thickener-defoamer solution by adding 0.5 to 1.5 parts by weight of an anti-foaming agent to the thickener solution based on 100 parts by weight of the water; A sixth step of preparing a slaked lime suspension by adding 30 to 40 parts by weight of slaked lime mixture, 11 to 15 parts by weight of white pigment, and 6 to 8 parts by weight of crystalline dolomite to the thickener-defoaming agent solution based on 100 parts by weight of water; A seventh step of preparing a slaked lime dispersion suspension by adding 0.5 to 1.5 parts by weight of a dispersant based on 100 parts by weight of water to the slaked lime suspension; and an eighth step of preparing a lime-based water-based exterior paint by adding 30 to 40 parts by weight of an acrylic resin to the slaked lime dispersion suspension based on 100 parts by weight of water. Provides a manufacturing method for exterior paint.

Since the production of quicklime using the oyster shells was explained through the method for producing quicklime using the oyster shells, it is not described to avoid duplication of the specification.

The quicklime mixture is mixed with water at a weight ratio of 1:1.5 to 2.5 to prepare a quicklime suspension, and becomes a slaked lime (Ca(OH) ₂ ) mixture through a hydration reaction for 25 to 30 minutes. Preferably, the quicklime mixture is mixed with water at a weight ratio of 1:2 and the hydration reaction is performed for 26.5 minutes. If the mixing ratio of the quicklime mixture and water is less than 1: 1.5, the water content is small and hydration is not sufficiently achieved, so the production yield of slaked lime may be reduced. If the mixing ratio of the quicklime mixture and water is more than 1: 2.5, the water content is high and the hydration temperature is lowered. Since hydration has to take longer due to lowering, the production yield of slaked lime may decrease. The slaked lime mixture prepared through the hydration reaction is characterized in that it contains calcium hydroxide (Ca(OH) ₂ ) and calcium carbonate (CaCO ₃ ) as calcium components in a weight ratio of 96.5 to 97.5:2.5 to 3.5.

The slaked lime prepared above can be manufactured into a lime-based water-based external paint by mixing a thickener, antifoaming agent, white pigment, crystalline dolomite, and acrylic resin.

The thickener may be PVA and may be added in an amount of 7 to 8 parts by weight based on 100 parts by weight of water contained in the lime-based water-based exterior paint. The antifoaming agent may be Lumiten and may be added in an amount of 0.5 to 1.5 parts by weight based on 100 parts by weight of water contained in the lime-based water-based exterior paint. The slaked lime mixture may be added in an amount of 30 to 40 parts by weight based on 100 parts by weight of water contained in the lime-based water-based exterior paint. The white pigment may be titanium dioxide (TiO ₂ ) and may be added in an amount of 11 to 15 parts by weight based on 100 parts by weight of water contained in the lime-based water-based exterior paint. The crystalline dolomite (CaMgCO ₃ ) can be used as a fine powder of 200 mesh or less and can be added in an amount of 6 to 8 parts by weight based on 100 parts by weight of water contained in lime-based water-based exterior paint. The dispersant may be LOPON and may be added in an amount of 0.5 to 1.5 parts by weight based on 100 parts by weight of water contained in the lime-based water-based exterior paint. The acrylic resin may be added in an amount of 30 to 40 parts by weight based on 100 parts by weight of water contained in the lime-based water-based exterior paint. The lime-based water-based exterior paint of the present invention manufactured by the above manufacturing method satisfies the KS water-based exterior paint type 1, grade 2 standards and is therefore expected to be commercialized immediately.

The present invention will be described in detail below through examples.

Example

1. Production of quicklime using oyster shells

Oyster shells were washed, pulverized, and sieved through a 200 or 325 mesh sieve to prepare oyster shell fine powder with an average particle size of 74 ㎛ or less or 45 ㎛ or less. For the oyster shell fine powder, X-ray diffraction analysis (X-Ray Diffraction, model: ZSX Primus II, Rigaku Co. Ltd., Japan) and field scanning electron microscopy (SEM; model: S-4300, HITACHI Co. Ltd., Japan) were performed.

Table 1 shows the chemical analysis results (XRF) of oyster shells.

Component(Unit : wt%) Sieve CaO SiO ₂ Na ₂ O SO ₃ MgO other _CO2 200 mesh 51.0 2.23 0.904 0.288 0.205 1.873 43.5 325 mesh 52.4 0.911 0.806 0.418 0.360 1.005 44.1

In the case of oyster shell fine powder with an average particle size of 74㎛ or less, CaO 51.0 wt%, SiO ₂ 2.23 wt%, Na ₂ O 0.904 wt%, SO ₃ 0.288 wt%, MgO 0.205 wt%, and CO ₂ 43.5 wt%; In the case of oyster shell fine powder with an average particle size of 45㎛ or less, CaO 52.4 wt%, SiO ₂ 0.911 wt%, Na ₂ O 0.806 wt%, SO ₃ 0.418 wt%, MgO 0.360 wt%, and CO ₂ 44.1 wt%. .

Figure 1 shows the results of XRD analysis of the crystal structures of oyster shell fine powder with an average particle size of 74㎛ or less and oyster shell fine powder with an average particle size of 45㎛ or less.

In the case of oyster shell fine powder with an average particle size of 74㎛ or less, CaCO ₃ and SiO ₂ were confirmed, and the content of aragonite crystal phase was 95.2 wt%, calcite crystal phase was 2.3 wt%, and SiO ₂ was 2.5 wt%. On the other hand, in the case of oyster shell fine powder with an average particle size of 45㎛ or less, the content of CaCO ₃ in the form of calcite crystals is analyzed to be 100.0wt%. Judging from the above analysis results, it can be seen that the impurity content of oyster shell fine powder decreases as the particle size decreases.

Quicklime (CaO) was prepared by calcining the oyster shell fine powder. Heat decomposition or calcination reaction of oyster shell fine powder is shown in Scheme 1 below.

[Reaction Formula 1]

CaCO ₃ → CaO + CO ₂ ↑

The oyster shell fine powder of the present invention undergoes thermal decomposition (decarboxylation) at around 900°C, and CO ₂ of CaCO ₃ , the main component of oyster shell, is decomposed and quicklime (CaO) is generated as a final product. In the present invention, in order to produce quicklime with a calcination rate of 99.0% or more, thermal analysis using a differential scanning calorimeter (DSC) was performed on the oyster shell fine powder to derive optimal calcination conditions.

The oyster shell fine powder was thermally decomposed (decarboxylation reaction) in an electric furnace at different firing temperatures and holding times. The electric furnace of the present invention used an external heating type electric furnace (AJeon furnace Co., Ltd., Korea, heating element: super kanthal), and as an alumina crucible, the firing temperature was in the range of 950℃, 1,050℃, and 1,150℃, and the temperature increase rate was was 10°C/min. In order to determine the plasticity characteristics, the holding time was set to 1 hour, 2 hours, and 3 hours to check the change in plasticity rate for the sample fired under each temperature condition, and X-ray diffraction analysis, X-ray fluorescence analysis, and electric field scanning were performed. Electron microscopic analysis was performed. An X-ray diffraction analyzer (XRD, model: D/MAX2500V/PC, Rigaku Co. Ltd., Japan) was used to analyze the crystal phase of quicklime (CaO), and an (X-Ray Fluorescence, XRF, model: ZSX Primus II, Rigaku Co. Ltd., Japan) was used. Changes in the surface shape of quicklime were confirmed using a Field Emission Scanning Electron Microscope (SEM; model: S-4300, HITACHI Co. Ltd., Japan).

Figure 2 shows the results of TG-DSC analysis of the thermal decomposition (decarboxylation) characteristics of oyster shell fine powder with an average particle size of 74㎛ or less and oyster shell fine powder with an average particle size of 45㎛ or less.

As a result of the analysis, it was confirmed that in the case of oyster shell fine powder with an average particle size of 74㎛ or less, 43.48% of CO ₂ was decomposed at a thermal decomposition (decarboxylation) temperature of 919.87℃ to produce quicklime (CaO), and in the case of oyster shell fine powder with an average particle size of 45㎛ or less. In the case of oyster shell fine powder, it was confirmed that 44.10% of CO ₂ was decomposed at a thermal decomposition temperature of 904.43°C to produce quicklime (CaO).

Figure 3 and Table 2 show the XRD change and crystal phase according to the holding time at each firing temperature in the electric furnace for the oyster shell fine powder with an average particle size of 45㎛ or less of the present invention.

As a result of the experiment, at an electric furnace sintering temperature of 950°C for 1 hour, CaCO ₃ and The contents of CaO were 86.9 wt% and 13 wt% (calcination rate 33.9%), respectively; At 1,050℃ for 1 hour, CaCO ₃ and The CaO content was 68.2 wt% and 31.8 wt% (calcination rate 48.8%), respectively, and it was confirmed that the decarboxylation reaction did not occur well. On the other hand, in the case of an electric furnace sintering temperature of 1,150°C, CaCO 3 and CaCO ₃ out of the total calcium components at 3 hours of sintering time. It was confirmed that a complete decarboxylation reaction was performed with CaO contents of 0.4 wt% and 99.6 wt% (calcination rate 99.6%), respectively.

Crystal phase(wt%) Calcination rate(%) CaCO ₃ CaO 950℃/1 hour 86.9 13.1 33.9 1,050℃/1 hour 68.2 31.8 48.8 1,150℃/1 hour 56.5 43.5 66.7 1,150℃/2 hours 23.5 76.5 90.4 1,150℃/3 hours 0.4 99.6 99.6

2. Comparison of the quality of quicklime manufactured from oyster shells and quicklime manufactured using regular limestone

Generally, limestone is used to produce quicklime. The limestone is classified into high-grade limestone with a quicklime content of more than 54 wt%, medium-grade limestone with a quicklime content of 54 to 52 wt%, and medium-grade limestone with a quicklime content of less than 52 wt%.

Table 3 shows the components of the oyster shell fine powder and limestone with an average particle size of 45㎛ or less of the present invention.

sample component(Unit : mass %) CaO MgO SiO _{2 CO2} other high grade limestone 54.811 0.238 1.029 43.634 0.288 medium grade limestone 53.486 0.203 3.366 42.832 0.113 low grade limestone 52.375 1.580 2.133 43.527 0.385 Oyster shell fine powder (less than 45㎛) 52.4 0.36 0.911 44.1 2.229

According to Table 3, the oyster shell fine powder (45㎛ or less) of the present invention has a quicklime (CaO) content of 52.4%, so it is confirmed to correspond to the level of low-grade limestone.

Table 4 shows the results of producing quicklime by calcining the high-grade limestone, medium-grade limestone, low-grade limestone, and oyster shell fine powder (45㎛ or less). The firing conditions for the limestone were 1 hour at 950°C, which is the firing condition for general quicklime products.

Firing conditions component(Unit : mass %) CaO MgO Al ₂ O ₃ SiO _{2 Fe2O3 _} high grade limestone 950℃/1 hour 99.5 0.31 0.06 0.02 0.11 medium grade limestone 950℃/1 hour 98.1 1.05 0.225 0.217 0.408 low grade limestone 950℃/1 hour 93.3 5.04 0.047 0.746 0.867 Oyster shell fine powder (less than 45㎛) 1,150℃/3 hours 99.2 0.457 0.225 0.253 0.122

According to Table 4, in the case of quicklime manufactured by calcining the oyster shell fine powder (45㎛ or less) of the present invention under optimal firing conditions, the quicklime content is 99.2%, and the quicklime manufactured by calcining mid-grade limestone (content 98.1%) It was confirmed that not only was the content higher, but it was similar to quicklime (99.5% content) manufactured by calcining high-quality limestone.

According to the results in Table 3, it is confirmed that the oyster shell fine powder (45㎛ or less) of the present invention has a quicklime (CaO) content of only 52.4%, which is only at the level of low-grade limestone.

In general, low-quality limestone has a high impurity content, so there is no choice but to improve the quality through additional processes or to purchase and mix high-quality limestone separately to produce products. As shown in Table 4, quicklime manufactured using low-grade limestone has an impurity content of 6 to 7%, so it is judged to be difficult to use as a quicklime product.

On the other hand, the quicklime manufactured using the oyster shell fine powder (45 ㎛ or less) of the present invention is a high-quality limestone, unlike low-grade limestone, even though the quicklime content of the raw material oyster shell fine powder (45 ㎛ or less) is only at the level of low-grade limestone. It was confirmed to have a quicklime content of similar quality to quicklime manufactured using limestone.

The above results show that the quicklime content is only at the level of low-grade limestone, and the discarded oyster shells are crushed to an average particle size of 45㎛ or less and calcined at 1,150℃/3 hours to produce a level equivalent to quicklime manufactured using high-grade limestone. Since it means that high-quality quicklime can be manufactured, it is expected to enable the production of added value through recycling of oyster shells.

2. Hydration characteristics of quicklime prepared from oyster shells and production of slaked lime using the same

Quicklime (CaO) was prepared from oyster shell fine powder with an average particle size of 45㎛ or less under firing conditions of 1,150°C/3 hours (calcination rate of 99.6% or more), and then a hydration reaction was performed using the quicklime in accordance with the ASTM C 110 standard. Conversion to Ca(OH) ₂ was confirmed.

The ASTM C 110 test conditions of the present invention are as follows. The initial starting temperature is filled with distilled water at room temperature, added quicklime to the Dewar flask at a weight ratio of quicklime:water = 1:4 or 1:2, and then stirred. The stirring speed was based on 400rpm ± 50rpm, and the temperature change over time was measured. Activity tests were conducted using thermometers with a precision of 0.1°C in the range of 0 to 100°C, and reactivity was confirmed using the reaction time at the highest temperature.

In the hydration reactivity test of quicklime (CaO), the hydration reaction equation is shown in Scheme 2.

[Scheme 2]

CaO+H ₂ O → Ca(OH) ₂

Initially, the hydration temperature was set to room temperature, activity was measured, and the product was confirmed by XRD and SEM.

Figure 4 shows the temperature change results of the ASTM C 110 test according to the CaO/water mixing conditions of the present invention.

As a result of the experiment, it was confirmed that the CaO/water 1:4 mixing condition had low reactivity, and the maximum temperature was 59.5°C and the maximum temperature reaching time was 58.0 minutes. In addition, the CaO/water 1:2 mixing condition was confirmed to have moderate reactivity, with a maximum temperature of 99.9°C and a time to reach the maximum temperature of 26.5 minutes.

Figure 5 and Table 5 show the XRD analysis and Q-XRD analysis results of the hydration reactant prepared by the ASTM C 110 test according to the CaO/water mixing conditions of the present invention.

Crystal phase(wt%) Ca(OH) ₂ CaCO ₃ CaO:H ₂ O=1:4 96.2 3.8 CaO:H ₂ O=1:2 97.0 3.0

As a result of the analysis, it was confirmed that all calcium components among the hydration reactants produced under all CaO/water mixing conditions were Ca(OH) ₂ and CaCO _3. In the case of CaO/water 1:4 mixing conditions, Ca(OH) ₂ was found to be among the total calcium components. It _{was confirmed that Ca(OH) 2 was 97.0 wt% and CaCO 3 was 3.0} wt% among the total calcium components in the case of CaO/water 1:2 mixing conditions.

Figure 6 shows the SEM analysis results of the hydration reactant prepared by the ASTM C 110 test according to the CaO/water mixing conditions of the present invention.

As a result of the analysis, it was confirmed that the hydration reactant in the CaO/water 1:4 mixing condition showed a heterogeneous shape as Ca(OH) ₂ , and in the case of the hydration reactant in the CaO/water 1:2 mixing condition, the CaO/water 1:4 mixing condition was confirmed. Compared to the hydration reactant under the conditions, Ca(OH) ₂ shows a distinct hexagonal plate shape and the particle size is confirmed to be smaller, around 10㎛.

Based on the results of the above firing and hydration experiments, the optimal firing conditions for producing quicklime (CaO) using oyster shell fine powder (main ingredient CaCO ₃ ) with an average particle size of 45㎛ or less are a firing temperature of 1,150°C/3 hours (quicklime It was confirmed that the plasticity rate was 99.6%).

The optimal hydration reaction condition for producing slaked lime (Ca(OH) ₂ ) using quicklime (CaO) prepared under the above conditions is a CaO/water 1:2 mixing condition that takes 26.5 minutes to reach a maximum temperature of 99.9°C. It was confirmed that it was. In addition, the CaO/water 1:2 mixture showed a faster reaction rate and higher temperature compared to the 1:4 mixture. As a result of SEM confirmation, it was confirmed that Ca(OH) ₂ prepared by hydration under CaO/water 1:2 mixing conditions had a distinct hexagonal plate shape.

As a result, when producing slaked lime by hydrating quicklime prepared using fine powder of oyster shells with an average particle size of 45㎛ or less, it is more economical to carry out the CaO/water 1:2 mixing condition as slaked lime can be obtained in a faster time. In addition, the manufactured slaked lime also has a regular hexagonal plate shape and has a small particle size of around 10 ㎛, so it is expected to have better fluidity and dispersibility.

3. Production of lime paint

Lime paint was prepared using slaked lime (Ca(OH) ₂ ) prepared by performing a hydration reaction under the CaO/water 1:2 mixing condition. The lime paint can be used as a lime-based water-based paint for exterior use.

First, Ca(OH) ₂ in the plaster form was dried in a hot air dryer at 100°C for 1 hour to prepare Ca(OH) ₂ in powder form.

Table 6 shows the composition and mixing method of the lime-based water-based paint prepared using the Ca(OH) ₂ powder prepared above.

Mixture composition Materials Parts by weight(g) Slaked lime (Ca(OH) ₂ ) 350Parts by weight(g) White pigment (TiO ₂ ) 130Parts by weight(g) Crystalline dolomite (less than 200 mesh) 75Parts by weight(g) Thickener (PVA) 75Parts by weight(g) Antifoam (Lumiten) 10Parts by weight(g) Dispersant (LOPON) 10Parts by weight(g) Acrylic resin (Acronal 296D) 350Parts by weight(g) Water 1,0000Parts by weight(g) Mixing conditions Stirring method Wet ball milling: 2000 to 2500 rpm Stirring time About 1 hour Mixing order 1) Prepare a thickener solution by mixing water (1L) and thickener.
2) Add a defoamer to the thickener solution to prepare a thickener-defoamer mixed solution.
3) Add slaked lime powder, white pigment, and crystalline dolomite to the thickener-defoamer mixed solution to prepare slaked lime suspension.
4) Adding a dispersant to the slaked lime suspension.
5) Add acrylic resin to the Ca(OH) ₂ suspension to which the dispersant was added.

The performance of the lime-based water-based paint prepared by the method in Table 6 was measured according to the KS M 6010 test method, which is the KS standard. The KS M 6010 test method includes (1) permeability (K.U.) measured with a Creve Stormer viscometer, (2) solidification time, (3) 45°, 0° diffuse reflectance (white), (4) hiding rate, ( 5) Wet coating film hiding rate, (6) Condition in container, (7) Accelerated weather resistance (200 hours) - Appearance, (8) Accelerated weather resistance (200 hours) - Yellowness difference, (9) Alkalinity resistance. .

Table 7 shows the KS M 6010 test results for the lime-based water-based exterior paint of the above example.

Test Items
(KS M 6010) Example KS water-based exterior paint type 1, grade 2 standard note lead 94K.U. 80~110K.U. 25±0.5℃ Solidification drying time 30min Within 60min 23±1℃
50±4%RH 45°. 0° diffuse reflectance (white) 91% More than 80% 23±2℃
50±5%RH Concealment rate 97% More than 94% 23±2℃
50±5%RH Wet film hiding rate 96% 1) The difference between the wet and dry film hiding rates is 2% or less. 23±2℃
50±5%RH Dry concealment rate 97% my state of courage fitness 1) Easy to mix to a uniform state
2) No impurities, lumps, and decay - Promotes weatherization - appearance fitness 1) 200 hours test standard
2) No chalking
2) The difference in yellowness of white is less than 0.12
3) Color change in light and other colors (△ L ) less than 4.0 - Promotes weather resistance - yellowing degree tea fitness
(0.04) - Alkali resistance fitness 1) There should be no wrinkles, cracks, swelling or peeling.
2) There should not be a large difference in color and gloss between the immersed and non-immersed parts. -

4. Conclusion

In the present invention, quicklime is manufactured through calcination using oyster shells produced in coastal areas of Korea as a raw material, the quicklime is reacted with water to produce Ca(OH) ₂ , and the applicability of this to lime-based water-based paint is tested. Through this, the following conclusions were drawn.

1) In order to manufacture high-quality quicklime using oyster shells as a raw material, it is possible to produce quicklime of more than 99.6% by crushing oyster shells to an average particle size of 45㎛ or less and then heat-treating them in an electric furnace at a temperature of 1,150℃/3 hours.

2) If a quicklime suspension is prepared from the prepared quicklime under the mixing conditions of CaO:H ₂ O=1:2 and then subjected to a hydration reaction, slaked lime can be produced in a short period of time (maximum temperature 99.9°C/arrival time 26.5 minutes). The slaked lime produced by this method is a homogeneous slaked lime in the form of a hexagonal plate and has excellent fluidity and dispersibility, so it is easy to mix as a raw material for paint and its quality is excellent.

3) The lime-based water-based exterior paint using slaked lime manufactured using oyster shells of the present invention as the main raw material satisfies the KS M 6010 (2014) standard water-based exterior paint type 1 class 2 standard items, so it can be immediately commercialized and commercialized. there is.

Therefore, by using the manufacturing method of the present invention, oyster shells discarded as marine waste can be recycled and commercialized in an environmentally friendly manner, thereby not only saving oyster fishermen's oyster shell processing costs, but also generating profits as a raw material for lime-based water-based exterior paint. It is expected that we will be able to create.

The specific embodiments described in this specification are meant to represent preferred embodiments or examples of the present invention, and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that modifications and other uses of the present invention do not depart from the scope of the invention as set forth in the claims herein.

Claims (8)

delete delete delete A first step of washing the oyster shells and producing oyster shell fine powder with an average particle size of less than 50㎛;
A second step of producing a quicklime (CaO) mixture by calcining the oyster shell fine powder at 1,100 to 1,200°C for 2 hours and 30 minutes to 3 hours and 30 minutes;
A third step of preparing a quicklime suspension by mixing the quicklime mixture and water at a weight ratio of 1:1.5 to 2.5 and performing a hydration reaction for 25 to 30 minutes to prepare a slaked lime (Ca(OH) ₂ ) mixture;
A fourth step of preparing a thickener solution by adding 7 to 8 parts by weight of a thickener based on 100 parts by weight of water;
A fifth step of preparing a thickener-defoamer solution by adding 0.5 to 1.5 parts by weight of an anti-foaming agent to the thickener solution based on 100 parts by weight of the water;
A sixth step of preparing a slaked lime suspension by adding 30 to 40 parts by weight of slaked lime mixture, 11 to 15 parts by weight of white pigment, and 6 to 8 parts by weight of crystalline dolomite to the thickener-defoaming agent solution based on 100 parts by weight of water;
A seventh step of preparing a slaked lime dispersion suspension by adding 0.5 to 1.5 parts by weight of a dispersant based on 100 parts by weight of water to the slaked lime suspension; and
An eighth step of preparing a lime-based water-based exterior paint by adding 30 to 40 parts by weight of an acrylic resin to the slaked lime dispersion suspension based on 100 parts by weight of the water;
A method for manufacturing a lime-based water-based exterior paint using oyster shell, comprising:
The method of claim 4, wherein the oyster shell fine powder has a CaO content of 50 to 53 wt%.
The method of claim 4, wherein the calcination rate is 99 to 99.9% and the quicklime mixture prepared through the calcination has a quicklime (CaO) content of 98.5 to 99.9 wt% using oyster shells. Method for manufacturing lime-based water-based exterior paint.
The lime system using oyster shell according to claim 4, wherein the slaked lime mixture contains calcium hydroxide (Ca(OH) ₂ ) and calcium carbonate (CaCO ₃ ) as calcium components in a weight ratio of 96.5 to 97.5:2.5 to 3.5. Method for producing water-based exterior paint.
The method of manufacturing a lime-based water-based exterior paint using oyster shell according to claim 4, wherein the lime-based water-based exterior paint satisfies the KS water-based exterior paint type 1, grade 2 standards.