KR101232633B1 - The synthesis method of in-situ precipitated calcium carbonate(pcc) for improving the quality of old corrugated container(occ) - Google Patents

Abstract

PURPOSE: An in-situ PCC(Precipitated Calcium Carbonate) for improving the quality of OCC(Old Corrugated Container) is provided to improve optical property and to synthesize PCC. CONSTITUTION: An in-situ PCC of improving the quality of OCC comprises: a step of hydrating quick lime(CaO) in an in-situ reactor and preparing slaked lime(Ca(OH)_2); a step of inputting waste paper pulp slurry into the in-situ reactor; a step of stirring the inputted slaked lime(Ca(OH)_2) and waste paper pulp slurry at a constant temperature and synthesizing in-situ PCC; and a step of finishing the reaction. [Reference numerals] (AA) Quicklime CaO; (BB) Optimal PCC synthesis condition for paper; (CC) Slaked lime Ca(OH)_2; (DD) Introducing waste paper pulp slurry; (EE) Mixing upper level pulp; (FF) Papermaking process; (GG) Intensity improvement by the increase of fiber bond

Description

The synthesis method of In-situ Precipitated Calcium Carbonate (PCC) for improving the quality of Old Corrugated Container (OCC)}

The present invention relates to a method for synthesizing In-Situ precipitated calcium carbonate (PCC) for improving the quality of corrugated cardboard to replace old newspaper (ONP) by recycling low-grade waste paper such as old corrugated container (OCC). .

As demand for paper continues to grow, the importance of recycling low-end waste paper, such as old newspapers and old corrugated containers, continues to increase. Currently, various kinds of notices are generated in Korea, but cardboard notices (about 65%) and newspaper notices (21.5%) make up most of them. In the case of corrugated cardboard, most of what is produced in Korea is recycled and used, and thus, the price is very low. However, in the case of newspaper magazines, the domestic production volume gradually decreases, and the dependence on imports is increasing, so that the price is rising. In general, the corrugated cardboard is the lowest quality of all kinds of paper, and since a large amount of foreign matter is mixed in the pulp, there is a disadvantage that it is difficult to improve the quality and recycle it. However, since the corrugated cardboard is the most frequently generated in Korea and the price is low, it is expected to bring various advantages to the paper industry if the quality of the corrugated cardboard can be improved by replacing the newspaper. Precipitated calcium carbonate (PCC) is currently used as an important filler in the paper industry, which is increasingly used not only for improving the optical properties of paper, but also for energy saving due to cost reduction as a pulp extender and improved drying efficiency. There is a growing trend.

In the case of corrugated cardboard (OCC), which accounts for the majority of domestic waste paper production, recycling is being made to produce similar quality products. The present invention provides a method for synthesizing in-Situ precipitated calcium carbonate (PCC), which is used as a method for improving the quality of corrugated cardboard (OCC) as a substitute for newspaper paper (ONP), which is increasing in price as the amount of generation decreases.

In the present invention, an in-situ PCC synthesis method for synthesizing precipitated calcium carbonate (PCC) in pulp slurry, which is simpler than the conventional process of directly filling filler into pulp slurry and has high retention ratio and high optical properties, is developed. This paper was applied to the low-cost corrugated paper pulp (OCC) pulp which occupies the largest proportion in Korea, and then mixed with newspaper paper (ONP) to improve the quality of the corrugated paper pulp (OCC) pulp. Developed as an alternative to ONP.

In the present invention, when the in-situ method is applied by mixing the corrugated cardboard (OCC), which occupies most of the waste paper generated in Korea, with the news paper (ONP), the optical properties are significantly improved compared to the characteristics of the corrugated cardboard (OCC) itself. The mixing ratio of 50 also showed whiteness similar to that of the old newspaper (ONP). The application of in-situ based on the corrugated cardboard (ONP) improved about twice as much as the reduction of thermal shortening to about 0.5km.

Figure 1. Flow chart between pulp mixing after precipitated calcium carbonate (PCC) synthesis
Figure 2. Flow chart of precipitated calcium carbonate (PCC) synthesis method after mixing between pulp
3. Schematic diagram of the in-situ reactor
Figure 4. Evaluation of the mechanical properties of the grass paper according to the mixing ratio
5. In-Situ process flowchart according to the present invention
Figure 6. Measurement results of white paper according to the mixing ratio
Figure 7. ERIC measurement results of grassland according to the mixing ratio
Figure 8. (OCC + ONP) method surface photograph using SEM
9. Enlarged Picture of FIG.
Figure 10. XRD results of the paper sheet to which the In-Situ process is applied

The inventors of the present invention improves the quality of the corrugated cardboard (OCC), which occupies most of the domestic waste paper, to replace the newspaper paper (ONP), in the in-situ method to the cardboard paper (OCC) and newspaper paper (ONP) pulp A method of applying precipitated calcium carbonate (PCC) was derived.

The application of precipitated calcium carbonate (PCC) of the in-situ method was derived from the present invention as a very efficient process for adding precipitated calcium carbonate (PCC) in terms of improving the optical properties of the paper, even if the mechanical properties of the paper are reduced. By using the treated pulp and mixed with the advanced pulp, the method of improving the optical properties and the mechanical properties was derived.

In order to apply the pulp-to-pulp mixing method according to the present invention, two methods were derived. Firstly, the precipitated calcium carbonate (PCC) is applied to the lower pulp to improve the optical characteristics by in-situ method, and then mixed with the upper pulp. Second, after mixing the pulp to be mixed, the in-situ method. The method of applying precipitated calcium carbonate (PCC) was derived.

Theoretically, it is difficult to compare each other because the input amounts of fillers are not the same in the two methods. However, the present invention has been completed by studying how the optical and mechanical properties of the paper change depending on the two methods. ,

FIG. 1 illustrates a method of mixing precipitated calcium carbonate (PCC) in an in-situ manner with a lower pulp to improve optical properties and mixing with the upper pulp.

As can be seen in the process diagram of FIG. 1, quicklime is hydrated in the in-Situ process to produce hydrated lime, in which waste paper pulp slurry is added to the manufactured lime, and CO 2 gas is blown to apply precipitated calcium carbonate (PCC) to lower pulp. The following shows how to mix the upper pulp.

Figure 2 shows a method of applying precipitated calcium carbonate (PCC) in-situ method after mixing the pulp to be mixed in the second method of the theory.

As can be seen in the process diagram of Fig. 2 in the in-Situ process, quicklime is hydrated to produce hydrated lime, and mixes the pulp to be mixed with the prepared hydrated lime, and blows CO2 gas into the precipitated calcium carbonate (PCC) It shows how to apply it.

Synthesis method of In-situ precipitated calcium carbonate (PCC) for the improvement of cardboard high paper quality of the present invention is prepared by (a) hydrated lime (CaO) in the In-situ reactor to produce hydrated lime (Ca (OH) 2) step; (b) introducing waste paper pulp slurry in an in-situ reactor; (c) synthesizing In-situ precipitated calcium carbonate (PCC) while stirring the slaked lime (Ca (OH) 2) and waste paper pulp slurry introduced into the in-situ reactor at a constant temperature; (d) terminating the reaction in a state in which the pH inside the In-Situ reactor is 6-7, and mixing the pulp slurry in which the reaction is completed through the steps (a) to (d) with the upper pulp. Step and final precipitated calcium carbonate (PCC) can be produced by putting the pulp synthesized in a sealed container for storage. In addition, the stirring temperature of the step (c) is most preferably at room temperature (15 ℃), the stirring speed is more preferably 600rpm. Figure 3 shows a schematic diagram of the in-situ reactor applied to the present invention. In this reactor, a carbonation reaction proceeds to synthesize precipitated calcium carbonate (PCC) in the pulp. Into the in-situ reactor, quick-lime (CaO) is added to the reactor, and 99% of high-purity carbon dioxide gas is added in accordance with the conditions for producing precipitated calcium carbonate (PCC). do. The process of carbonation reaction is as follows.

CaCO3 → CaO + CO2

CaO + H2O → Ca (OH) 2

Ca (OH) 2 + CO 2 → CaCO 3 + H 2 O

When the carbonation reaction starts, Ca (OH) 2, which is a basic substance generated in the reactor, meets CO 2, and CaCO 3 is generated. As a result, the pH of the slurry in the reactor gradually falls to neutral with time. When the pH drops to 6-7, it is determined that all Ca (OH) 2 materials in the reactor are made of CaCO3, and the reaction is terminated. The pulp slurry after the reaction is all put in a closed container for storing pulp slurry is used to produce a paper sheet.

Figure 4 shows a process diagram for synthesizing precipitated calcium carbonate in pulp in an in-situ method according to the present invention. As a preferred embodiment of the optimum in-situ synthesis conditions according to the present invention, the calcium oxide to be added is efficiently hydrated for about 30 minutes with a predetermined amount of distilled water before the addition, and 99% of high purity carbon dioxide is added in 1 L / When injected at a flow rate of min, the carbonation reaction in the reactor proceeds most efficiently. In addition, the pH meter is a measure to check the progress of the carbonation reaction in the reactor, the calcium oxide added in the reactor reacts with water to form a basic calcium hydroxide and meet the added carbon dioxide to produce CaCO3 and to produce water with it Let's go. Through this process, the pH of the slurry in the reactor gradually falls to neutral with time. When the pH drops to 6-7, all Ca (OH) 2 materials in the reactor are determined to be produced by CaCO3 and the reaction is terminated. Let's do it.

5 to 7 are results showing the evaluation of the paper quality characteristics according to the mixing ratio of the corrugated cardboard notice (OCC) and newspaper notice (ONP). 5 to 7 show the change in the physical properties of the paper by mixing the corrugated cardboard (OCC) and newspaper newspaper (ONP) in each mixing ratio and applying the precipitated calcium carbonate (PCC) in an in-situ method.

In FIG. 5, thermal short-length analysis of the mixed pulp after the first mixing followed by the in-situ process showed about 2.3 km for the OCP pulp itself, and about 3.28 km for the news paper ONP. Compared to OCC, the mechanical properties of the news paper (ONP) are slightly better. When the general in-situ precipitated calcium carbonate (PCC) input method is applied to the pulp of corrugated cardboard (OCC) and newsprint (ONP), it is 1.15km for corrugated paper (OCC) and 0.63km for newsprint (ONP). The mechanical properties of the paper are greatly reduced. However, after mixing between the pulp and applying the in-situ method, the corrugated cardboard (OCC) pulp with excellent fiber strength was mixed together and exhibited thermal shortening of more than 1km under all mixing conditions. Could be minimized.

In FIG. 6, it can be seen that the whiteness of the mixed pulp is significantly improved under all conditions when the precipitated calcium carbonate (PCC) synthesis conditions are applied after mixing between pulp in the case of whiteness which is considered as the most important in improving the quality of waste paper. As the mixing ratio of corrugated cardboard (ONP) increases, the whiteness gradually increases, but when the 50:50 blending condition (50% of the news paper (ONP) is replaced by the corrugated cardboard (OCC)), It can be seen that the optical properties can be greatly improved by displaying similar whiteness to the level of conventional newspaper notice (ONP). In addition, when 25% of the news paper (ONP) was replaced, the white paper value was over 60%, and even when the corrugated paper (OCC) was mixed, the white paper of the news paper (ONP) itself was much higher.

In FIG. 7, ERIC (Effective Residual Ink Concentration) measurement, which is one of the important optical characteristics considered when recycling waste paper, together with whiteness, shows the residual ink concentration of about 130 ppm in all mixing conditions, and displays the old corrugated cardboard (OCC) or newspaper paper ( It can be seen that the quality is further improved compared to ONP).

8 and 9 are In-Situ ONP surface photographing images using an electron micrograph (SEM), and FIG. 8 is an enlarged photograph.

Scanning microscopic images of precipitated calcium carbonate (PCC) particles produced in paper sheets were observed when incorporating corrugated paper pulp (OCC) pulp and newspaper paper pulp (ONP) pulp. 8 and 9, it can be seen that the nucleated precipitated calcium carbonate (PCC) particles are evenly distributed on the pulp surface, and the precipitated calcium carbonate (PCC) particles are simply added to the pulp surface. It can be seen that it is bonded to the fibrils of the pulp fibers rather than attached. This improved the whiteness of the paper through the light scattering of precipitated calcium carbonate (PCC) particles formed on the fiber surface when the in-situ precipitated calcium carbonate (PCC) synthesis method was applied. It can be seen that the optical properties such as reduction of residual ink concentration were improved by covering.

FIG. 10 is a graph of surface characteristics analysis of in-situ resin paper through XRD. FIG. X-ray diffraction analysis was performed to determine if the material produced on the pulp surface was calcite PCC and unreacted substances such as Ca (OH) 2 or impurities were present. The results are shown in the figure below. As a result, the material produced on the pulp fiber surface was identified as calcite PCC, and the PCC to be applied in this study was confirmed to be completely produced. In addition, it can be seen that there was no unreacted substance such as calcium oxide or calcium hydroxide, and no other impurities were present.

As a material for applying an embodiment of the present invention was used pulp that passed through the deoiling process (Old newspaper pulp; ONP) and corrugated cardboard (Old corrugated container; OCC) provided by the domestic H paper company, these The properties of the pulp itself are shown in Table 1 below. Limestone (Calcium oxide, Showa, assey 98%, Japan) was used to synthesize precipitated calcium carbonate (PCC) for application as a filler, and glass bubbler was used to efficiently inject 99.9% of high purity CO ₂ gas.

Pulp Type Whiteness (%) ERIC (ppm) Heat tower (km) Ash (%) Corrugated Cardboard Notice (OCC) 35.59 406 2.3 8.65 Newspaper Notice (ONP) 56.79 292.1 3.28 6.37

Table 2 below is a chart showing the measurement results of the physical properties of the two methods derived by the quality improvement method of the corrugated cardboard of the present invention. The lower waste paper pulp slurry was coated with corrugated cardboard (OCC), the upper pulp was applied with newspaper paper (ONP), and the pulp to be mixed with each other was applied with corrugated cardboard paper (OCC) and newspaper paper (ONP). .

Manufacturing process condition Whiteness (%) ERIC (ppm) Heat tower (km) Ash (%) OCC 35.59 406 2.3 8.65 OCC In-situ + ONP
(5: 5 mixed) 52.3 213.9 1.4 23.17 (ONP + OCC) In-situ
(5: 5 mixed) 57.09 138 1.1 38.02 ONP 56.79 292.1 3.28 6.37

In the analysis of Table 2, each mixing method showed a different ash content (filler holding amount), but when the cardboard notification (OCC) + newspaper notification (ONP) in-situ mixing method was applied, the ash content was high. As a result, the optical properties showed much better results, and in general, the mechanical properties that occur when the ash content is high also do not show much difference with the OCP in-situ + ONP mixing method. Able to know. Through this, in order to efficiently apply the corrugated cardboard (OCC) as a substitute for the newspaper paper (ONP), the precipitated calcium carbonate was mixed in the in-situ method with the mixed pulp and the paper (ONP) pulp. Applying (PCC) is the most appropriate. Therefore, in the present invention, after the mixing of the corrugated cardboard (OCC) + newspaper (ONP) was applied in-situ precipitated calcium carbonate (PCC) synthesis method, the mixing ratio of the cardboard (OCC) and newspaper (ONP) 25:75 , 50:50, and 75:25, respectively, to show how low-cost but low-quality corrugated cardboard (OCC) pulp can replace the rising newspaper (ONP) pulp, which has been rising. Can be.

1. CO2 gas, 2. Flow meter, 3. Agitator, 4. pH meter, 5. Temperature controller

Claims (4)

In-Situ precipitated calcium carbonate (PCC) synthesis method for improving the quality of corrugated cardboard
(a) hydrated quicklime (CaO) in an In-Situ reactor to prepare hydrated lime (Ca (OH) 2);
(b) introducing waste paper pulp slurry into the In-Situ reactor;
(c) synthesizing In-Situ precipitated calcium carbonate (PCC) while stirring the slaked lime (Ca (OH) 2) and waste paper pulp slurry introduced into the In-Situ reactor at a constant temperature;
(d) terminating the reaction at a pH of 6-7 in the In-Situ reactor.
The method of claim 1,
The waste paper pulp slurry of step (b) is a method of synthesizing In-Situ precipitated calcium carbonate (PCC) for improving the quality of corrugated cardboard, characterized in that the mixture of the lower pulp and the higher pulp.
The method of claim 1,
The waste paper pulp slurry of step (b) is corrugated cardboard (OCC) In-Situ precipitated calcium carbonate (PCC) synthesis method for improving the quality of cardboard.
The method of claim 1,
The stirring temperature of step (c) is room temperature (15 ° C.), and the stirring speed is 600 rpm, In-Situ precipitated calcium carbonate (PCC) synthesis method for improving cardboard quality.

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