FLEXIBLE CALCIUM CARBONATE WITH IMPROVED CALCIUM CARBONATE RETENTION, TISSUE PAPER INCLUDING THE SAME, AND MANUFACTURING METHOD THEREFOR

Abstract

 Herein disclosed are flexible calcium carbonate (FCC) comprising micro fibrillated cellulose (MFC) and calcium carbonate attached to the micro fibrillated cellulose, tissue paper containing the same, and a manufacturing method therefor.

Description

BACKGROUND OF THE INVENTION

1. Field of the invention

[0001] The present disclosure relates to flexible calcium carbonate (FCC) including micro fibrillated cellulose (MFC) and calcium carbonate attached to MFC, tissue paper including the same, and a manufacturing method therefor.

2. Description of the Prior Art

[0002] Calcium carbonate (CaCO₃) is used as an agent for improving physical properties in various industrial fields such as plastics, rubber, adhesives, coatings, and paper industries. Serving as a filler in the paper industry, calcium carbonate is applied to fine and uniform paper products due to its small and uniform particle size and low equipment wear and is known to contribute to the durability of pigments due to its small particle size, high absorption value, large oil absorptivity, and large surface area. Moreover, calcium carbonate is widely used in manufacturing polyethylene films with excellent breathability and water resistance for products such as tissue paper, feminine products, sanitary pads, and diapers. The small particle size advantageously allows calcium carbonate to find applications in products that are delicate, non-irritating to the skin, and do not cause sensory discomfort to the human body. However, a drawback also exists as the small particle size of calcium carbonate makes it difficult to retain in thin paper such as tissue paper, as it falls through the mesh during sheet formation. Consequently, Research is ongoing to increase the retention rate so that calcium carbonate can be properly retained in toilet paper without falling off.

SUMMARY OF THE INVENTION

[0003] The present disclosure was created to address the aforementioned issues encountered in the related art and aims to provide FCC with improved retention rates, tissue paper containing same, and a manufacturing method therefor, wherein the FCC includes micro fibrillated cellulose.

[0004] To achieve the goal, an embodiment of the present disclosure provides flexible calcium carbonate (FCC) including micro fibrillated cellulose (MFC) and calcium carbonate attached to the MFC.

[0005] Furthermore, the tissue paper according to the present disclosure may contain an amount of 1 to 10 weight parts of FCC according to various embodiments of the present disclosure.

[0006] A method for manufacturing tissue paper according to an embodiment of the present disclosure may include the steps of: preparing micro fibrillated cellulose (MFC); synthesizing calcium carbonate attached to the micro fibrillated cellulose to produce FCC; and adding the FCC into the tissue paper.

[0007] The tissue paper containing the FCC according to the present disclosure may have an improved retention rate.

[0008] Additionally, the brightness of the tissue paper may be increased.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The above and other aspects, features and advantages of the present disclosure will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is an SEM image of the MFC in Example 1;

FIGS. 2a, 2b, and 2c show SEM images depicting the width and length of the main and secondary branches;

FIG. 3 is an SEM image of the FCC in Example 1; and

FIG. 4 is an SEM image of the tissue paper according to Example 1.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0010] Unless defined otherwise, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology and are not to be interpreted in an idealized or excessively formal sense unless explicitly defined herein.

[0011] The flexible calcium carbonate (FCC) of the present disclosure may include micro fibrillated cellulose (MFC) and calcium carbonate (CaCO₃). Here, the calcium carbonate may be included in a form attached to the MFC. MFC, in a fibrillated form, can include numerous branches, which will be described in more detail in the description of the tissue paper manufacturing method of the present disclosure.

[0012] The MFC and calcium carbonate may have a weight ratio of 1:15 to 1:25 and preferably 1:20. The FCC with such a weight ratio may have lengths ranging from 20 µm to 40 µm.

[0013] The tissue paper according to the present disclosure may include FCC according to various embodiments in an amount of 1 to 10 weight parts.

[0014] A method for manufacturing tissue paper according to an embodiment of the present disclosure may include steps of: preparing micro fibrillated cellulose (MFC); synthesizing calcium carbonate attached to the MFC to produce FCC; and adding the FCC to the tissue paper.

[0015] The step of preparing MFC may be performed through a colloid mill. Specifically, the step can be done by beating hardwood pulp, dispersing same in purified water, and then grinding same in a colloid mill. As used herein, the term "hardwood pulp" refers to fibrous pulp obtained from dicotyledonous trees, i.e., deciduous or broad-leaved trees such as oak, cherry, ebony, mahogany, teak, lauwan, and red sandalwood, characterized by thin cell walls and short cellulose fibers. Hardwood pulp is softer and weaker than softwood pulp that will be described later. The term "softwood pulp" refers to fibrous pulp which is primarily obtained from coniferous trees like pine and fir, with the pulp morphology featuring thick cell walls and long pulp fibers. As mentioned above, softwood pulp is higher in strength and lower in softness than hardwood pulp. In the relevant technical field of the present invention, such classifications and terms are commonplace, and the present disclosure is not limited to any specific type of wood.

[0016] As described in the foregoing, the hardwood pulp can be mechanically ground through a colloid mill to afford fibrillated branches. More specifically, the MFC in the present disclosure may consist of main and secondary branches. Here, the main and secondary branches can be classified by the width and length of the branches, where the main branches can be 5 µm to 12 µm in width and 500 µm to 850 µm in length, and the secondary branches can be 60 nm to 400 nm in width and 8 µm to 18 µm in length. The aspect ratio of the main branches may be 75% to 100%, and the aspect ratio of the secondary branches may be 25% to 100%.

[0017] Furthermore, the mechanical grinding may be conducted such that the main and secondary branches exist at a ratio of 1:100 to 1:200.

[0018] In the step of synthesizing calcium carbonate attached to the MFC to produce FCC, the MFC and calcium carbonate may have a weight ratio of 1:15 to 1:25 and preferably 1:20. Additionally, the step of manufacturing FCC may be performed in a container into which CO₂ is introduced, which can help release unattached calcium carbonate. The produced FCC may have lengths of 20 µm to 40 µm. Additionally, the calcium carbonate included in the FCC may have a fusiform shape and be attached to the MFC.

[0019] In the step of adding the FCC to the tissue paper, the FCC may be included in an amount of 1 to 10 weight parts. The hardwood pulp typically added during the manufacture of tissue paper can be replaced by the FCC of the present disclosure, and by including such weight parts, tissue paper with an improved retention rate can be produced.

[0020] Below, a better understanding of the present disclosure may be obtained through the following examples, which are set forth to illustrate, but are not to be construed to limit, the present disclosure.

EXAMPLE 1

Step of Preparing Micro Fibrillated Cellulose

[0021] Hardwood pulp beaten to form a fiber width of 18. 2 µm and a length of 0. 81 mm was dispersed at 2 wt% in purified water and ground using a colloid mill. The disc gap of the colloid mill was maintained between 30 µm to 250 µm, and the disc speed was controlled between 1200 to 1900 rpm depending on the discharge pattern of the sample. Due to the swelling caused by the disc's frictional heat and the increase in sample viscosity, the micro fibrillated cellulose was produced with a total of 5 passes. The disc gap, temperature, and viscosity during the 5 passes are as shown in Table 1 below.

TABLE 1

Pass	Disc Gap (µm)	Temp. (°C)	Viscosity (cPs)
1 pass	30-160	20-25	2000
2 pass	120-230	25-30	4500
3 pass	120-240	30-35	7500
4 pass	130-250	35-40	12000
5 pass	130-250	40-45	17500

Step of Manufacturing Flexible Calcium Carbonate (FCC)

[0022] The prepared MFC was placed at a concentration of 1 to 2% in a 1-L or larger reaction vessel, along with 10% or higher of hydrated lime and water. Then, under conditions of a temperature of 40°C to 70°C and a CO₂ concentration of 20 to 30%, the FCC was produced at a stirring speed of 1000 to 2000 rpm.

Step of Adding FCC to Tissue Paper

[0023] Hardwood and softwood pulps were mixed at a 2:8 weight ratio and beaten to prepare a stock at a concentration of 3%. The mixed and beaten stock (95 weight parts) and the previously prepared FCC (5 weight parts) were combined and dispersed. Using a circular sheet machine with an area of 200 cm², a tissue paper containing the prepared materials, with a basis weight of 60g, was manufactured. The produced tissue paper was placed between absorbent papers, de-watered using a press, and then dried using a drum dryer to finally produce the tissue paper.

EXPERIMENTAL EXAMPLE 1

[0024] The MFC prepared in Example 1 was analyzed for structure, viscosity, and pH. FIG. 1 is an SEM image of the MFC from Example 1, and FIGS. 2a, 2b, and 2c show SEM images that display the width and length of the main and secondary branches. Referring to FIGS. 1 and 2, the main branches have a width of 5 µm to 12 µm and a length of 500 µm to 850 µm, and the secondary branches have a width of 60 nm to 400 nm and a length of 8 µm to 18 µm. Additionally, the MFC was measured to have a viscosity of 7000 to 10000 cPs and a pH of 7.

EXPERIMENTAL EXAMPLE 2

[0025] The FCC prepared in Example 1 was analyzed for structure, viscosity, and pH. FIG. 3 is an SEM image of the FCC from Example 1. Referring to FIG. 3, it is observed that the FCC has a length of 20 µm to 40 µm. Additionally, the FCC was measured to have a viscosity of 100 cPs to 500 cPs and a pH of 6 to 9.

EXPERIMENTAL EXAMPLE 3

[0026] The structure of the tissue paper manufactured according to Example 1 was observed, and the retention rate and brightness of the calcium carbonate in the tissue paper were measured.

Structure Observation

[0027] FIG 4 is an SEM image of the tissue paper according to Example 1. As seen in FIG. 4, it is evident that the calcium carbonate was well retained in the tissue paper even after finally manufacturing the tissue paper.

Measurement of Retention Rate

[0028] The tissue paper according to Example 1 and tissue paper without FCC (Comparative Example 1) were measured for calcium carbonate retention rate. To measure the retention rate, the amount of ash in the tissue paper base needed to be determined first, so an experiment to measure the ash content was conducted.

[0029] First, the tissue paper base of Example 1 and a crucible were dried in an oven at 105°C. Then, after weighing the crucible, 2 to 5g of the base were placed in the crucible and ashed in an electric muffle furnace at 525 °C for 4 to 5 hours. After ashing, the crucible was picked up with tongs and dried in an oven at 105°C. The crucible thus dried was then weighed to measure the ash content in the base. The ash content (%) is calculated according to the following Equation 1:

(W1: mass of the crucible and ash after ashing (g), W2: mass of the dried crucible (g), S: amount of ash (g))

[0030] The same process was also conducted for the tissue paper base of Comparative Example 1.

[0031] The retention rate (%) was then calculated by substituting the measured ash content (g) in the tissue paper bases of Examples 1 and Comparative Example 1 into the following Equation 2:

Retention Rate (%) = amount of ash (g) / amount of FCC added to the tissue paper base (g) × 100

[0032] As a result, the tissue paper according to Example 1 showed an increase in the retention rate of about 35 to 55% compared to Comparative Example 1.

Measurement of Brightness

[0033] The tissue paper according to Example 1 and Comparative Example 1 was measured for brightness using a brightness meter.

[0034] The results showed that the tissue paper according to Example 1 increased in brightness by 1.4 to 2.0 %p, compared to that according to Comparative Example 1.

[0035] While the present disclosure has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. The exemplary embodiments should be considered in descriptive sense only and not for purposes of limitation. Therefore, the scope of the invention is defined not by the detailed description of the invention but by the appended claims, and all differences within the scope will be construed as being included in the present disclosure.

Claims

1. A flexible calcium carbonate (FCC) comprising:

micro fibrillated cellulose (MFC); and

calcium carbonate attached to the micro fibrillated cellulose.

2. The flexible calcium carbonate (FCC) of claim 1, wherein the micro fibrillated cellulose and calcium carbonate have a weight ratio of 1:15 to 1:25.

3. The flexible calcium carbonate (FCC) of claim 2, wherein the FCC has a length ranging from 20 µm to 40 µm.

4. Tissue paper, comprising the flexible calcium carbonate (FCC) of any one of claims 1 to 3 in an amount of 1 to 10 parts by weights.

5. A method for manufacturing tissue paper, the method comprising the steps of:

preparing micro fibrillated cellulose (MFC);

synthesizing calcium carbonate attached to the micro fibrillated cellulose (MFC) to produce flexible calcium carbonate (FCC); and

adding the flexible calcium carbonate (FCC) to the tissue paper.

6. The method of claim 5, wherein the step of preparing micro fibrillated cellulose is performed using a colloid mill.

7. The method of claim 5, wherein the step of preparing micro fibrillated cellulose is performed such that the micro fibrillated cellulose comprises main and secondary branches, with main and secondary branches existing at a ratio of 1:100 to 1:200.

8. The method of claim 7, wherein the main branches have a width of 5 µm to 12 µm and a length of 500 µm to 850 µm, and the secondary branches have a width of 60 nm to 400 nm and a length of 8 µm to 18 µm.

9. The method of claim 5, wherein in the step of producing the flexible calcium carbonate (FCC), the micro fibrillated cellulose and calcium carbonate have a weight ratio of 1:15 to 1:25.

10. The method of claim 5, wherein the step of producing the flexible calcium carbonate (FCC) is performed in a container into which CO₂ is introduced.

11. The method of claim 5, wherein the step of producing the flexible calcium carbonate (FCC) is performed such that the FCC has a length of 20 µm to 40 µm.

12. The method of claim 5, wherein the step of adding the flexible calcium carbonate (FCC) to the tissue paper comprises incorporating 1 to 10 weight parts of the flexible calcium carbonate (FCC).

Drawing