Cigarette paper and preparation method thereof

Abstract

The invention discloses cigarette paper and a preparation method thereof, and belongs to the technical field of papermaking. The cigarette paper is prepared from slurry, calcium carbonate and auxiliaries, the calcium carbonate is a mixture of liquid precipitated calcium carbonate and powder precipitated calcium carbonate, the crystal form of liquid precipitated calcium carbonate single crystals is fusiform, the length of the liquid precipitated calcium carbonate single crystals is 1200-1850 nm, the diameter of the liquid precipitated calcium carbonate single crystals is 200-290 nm, the length-diameter ratio of the liquid precipitated calcium carbonate single crystals is 4.5-7.0, and the length-diameter ratio of the liquid precipitated calcium carbonate single crystals is 4.5-7.0. The weight ratio of the liquid precipitated calcium carbonate in the calcium carbonate is 10%-100%. According to the invention, the liquid precipitated calcium carbonate with specific parameters also realizes higher rib strength under lower rib roller pressure, and the service life of the rubber covered roller is prolonged. In addition, the use of liquid precipitated calcium carbonate does not have negative effects on other properties of the paper.

Description

Technical Field

[0001] The present invention relates to the technical field of papermaking, and more specifically, to cigarette paper and a preparation method thereof. Background Art

[0002] Cigarette paper is a thin sheet of paper specially used for wrapping tobacco to make cigarettes. It is made of pulp, calcium carbonate and additives. Cigarette paper is white, tight, soft and delicate, with high opacity, high longitudinal tensile strength, certain air permeability and suitable burning speed.

[0003] The rib of cigarette paper is an important appearance indicator of cigarette paper. Rib refers to the embossing left on cigarette paper by mechanical action. There are generally three types of embossing processes, namely wet embossing, dry embossing and off-machine embossing. Among them, off-machine embossing is rarely used. Dry embossing has a limited application range because of the high pressure applied, great damage to the equipment and the difficulty in controlling the stability of the rib strength. Wet embossing is performed after the paper web leaves the pressing section and before entering the drying section. At this time, the paper web has been initially formed and has not undergone the drying process. The paper fiber is soft and easy to press and form. At present, most high-end cigarette papermaking machines at home and abroad use wet embossing technology. The equipment used for cigarette paper embossing is a pair of rib rollers, one of which is a steel silk roller with the required pattern engraved on the surface; the other is a rubber-coated roller, which is generally replaced regularly or irregularly according to the usage status.

[0004] The rib strength of cigarette paper reflects the depth of the ribs of cigarette paper. The higher the rib strength of cigarette paper, the deeper and clearer the ribs are. The cigarette paper manufacturing industry generally uses visual inspection to measure the rib strength of cigarette paper, but visual inspection is highly subjective and there are too many factors that affect the judgment of rib strength. In recent years, the industry has gradually promoted the use of cigarette paper rib strength testers to quantify the rib strength of cigarette paper.

[0005] For cigarettes, the style and strength of the ribs of cigarette paper affect the style of cigarettes to a certain extent. Therefore, various Chinese tobacco companies pay more and more attention to the rib strength of cigarette paper when selecting cigarette paper for their products, and gradually incorporate rib strength into standard requirements, which even affects the selection of cigarette paper.

[0006] In the cigarette paper production process, increasing the rib roller pressure is the most direct and effective way to increase the rib strength of cigarette paper. This is because as the rib roller pressure increases, the greater the embossing roller pressure acting on the paper web, the lower the opacity of the embossed area, resulting in a greater difference in paper opacity between the embossed area and the non-embossed area. Therefore, the higher the rib strength of the cigarette paper, the better. However, this method has very limited room for adjustment of the rib strength, and excessive rib roller pressure will significantly shorten the service life of the rubber-coated roller, increase production costs, and stop the machine to replace the rubber-coated roller, which will also extend the downtime and reduce production efficiency. Summary of the invention

[0007] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of the existing method for improving the rib strength of cigarette paper, that is, increasing the rib roller pressure, which leads to a decrease in the life of the rib roller, and the limited improvement in the rib strength, and to provide a cigarette paper that achieves a higher rib strength under a lower rib roller pressure by compounding liquid precipitated calcium carbonate and powder precipitated calcium carbonate with specific parameters, thereby improving the service life of the rubber-coated roller.

[0008] Another object of the present invention is to provide a method for preparing cigarette paper.

[0009] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0010] A cigarette paper is prepared from pulp, calcium carbonate and an additive, wherein the calcium carbonate is a mixture of liquid precipitated calcium carbonate and powdered precipitated calcium carbonate, the crystal form of the liquid precipitated calcium carbonate single crystal is spindle-shaped, the length of the liquid precipitated calcium carbonate single crystal is 1200-1850nm, the diameter of the liquid precipitated calcium carbonate single crystal is 200-290nm, and the aspect ratio of the liquid precipitated calcium carbonate single crystal is 4.5-7.0;

[0011] The weight ratio of the liquid precipitated calcium carbonate in the calcium carbonate is 10% to 100%.

[0012] In the art, calcium carbonate can be divided into liquid calcium carbonate and powdered calcium carbonate.

[0013] Liquid calcium carbonate can be prepared by precipitation or grinding.

[0014] The liquid precipitated calcium carbonate of the present invention refers to liquid calcium carbonate prepared by a precipitation method.

[0015] In the present invention, a higher rib strength is achieved under a lower rib roller pressure by compounding liquid precipitated calcium carbonate and powder precipitated calcium carbonate with specific parameters, thereby increasing the service life of the rubber-coated roller. Moreover, the use of liquid precipitated calcium carbonate will not have a negative impact on other properties of the paper. This may be because: the suspension after the preparation of the liquid precipitated calcium carbonate has not undergone a drying stage, the crystal structure is more complete, the crystal tip is sharper, and it is easy to embed into the fiber when squeezed by an external force, thereby reducing the interface between the calcium carbonate particles and the fiber; when the dimer size is consistent, the single crystal calcium carbonate with a larger aspect ratio can embed more volume into the fiber under the action of an external force, which can further reduce the interface between the calcium carbonate particles and the fiber, reduce the scattering surface and reflection surface of the irradiated light, thereby improving the transparency of the rib pressing area and increasing the contrast with the rib non-pressing area, that is, improving the rib strength.

[0016] Among them, the crystal form of the liquid precipitated calcium carbonate single crystal, the length of the liquid precipitated calcium carbonate single crystal, and the diameter of the liquid precipitated calcium carbonate single crystal are all photographed and measured by a scanning electron microscope and calculated by a statistical method.

[0017] The aspect ratio of the liquid precipitated calcium carbonate single crystal is obtained by calculating the ratio of the length of the single crystal to the diameter of the single crystal.

[0018] The length of the liquid precipitated calcium carbonate single crystal can be 1200nm, 1300nm, 1400nm, 1500nm, 1600nm, 1700nm, 1800nm, and 1850nm.

[0019] The diameter of the liquid precipitated calcium carbonate single crystal can be 200nm, 210nm, 220nm, 230nm, 240nm, 250nm, 260nm, 270nm, 280nm, and 290nm.

[0020] The aspect ratio of the liquid precipitated calcium carbonate single crystal can be 4.5, 5.0, 5.5, 6.0, 6.5, or 7.0.

[0021] Preferably, in the cigarette paper, a number of the liquid-precipitated calcium carbonate single crystals are combined to form calcium carbonate polymers, and the D50 of the polymers is 1.6-2.2 μm.

[0022] In precipitated calcium carbonate, calcium carbonate single crystals can combine to form calcium carbonate polymers similar to chrysanthemum petals. The inventors found that the D50 of this polymer also affects the rib strength, opacity and retention effect of the cigarette paper. The D50 of the polymer is 1.8-2.0 μm, which has higher rib strength, opacity and retention rate.

[0023] D50 means that the volume of particles smaller than and larger than it each accounts for 50% of the total volume.

[0024] In the present invention, the D50 of the polymer is measured by SediGraph III 5120 type sedimentation particle size analyzer.

[0025] It should be noted that the calcium carbonate polymers formed by the combination of liquid precipitated calcium carbonate single crystals are not spherical particles themselves. Its "diameter" is the equivalent spherical diameter, which does not represent the absolute diameter in the usual sense. It represents a distribution, that is, an integral curve that continuously changes from an upper limit value to a lower limit value. The diameter here is the statistical average of all changing values.

[0026] In the present invention, the weight ratio of the liquid precipitated calcium carbonate in the calcium carbonate can be 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 100%.

[0027] Preferably, the length of the liquid-precipitated calcium carbonate single crystal is 1250-1500 nm.

[0028] Preferably, the diameter of the liquid-precipitated calcium carbonate single crystal is 200-260 nm.

[0029] Preferably, the aspect ratio of the liquid-precipitated calcium carbonate single crystal is 5.3 to 6.1.

[0030] Preferably, the weight ratio of the liquid precipitated calcium carbonate in the calcium carbonate is 50% to 100%.

[0031] In the present invention, the proportion of liquid precipitated calcium carbonate in calcium carbonate is relatively high, which is beneficial to further improve the rib strength.

[0032] Preferably, the crystal form of the powder precipitated calcium carbonate single crystal is spindle-shaped, the length of the powder precipitated calcium carbonate single crystal is 901-1194 nm, the diameter of the powder precipitated calcium carbonate single crystal is 364-425 nm, and the aspect ratio of the powder precipitated calcium carbonate single crystal is 2.3-3.2.

[0033] Preferably, based on the mass of the cigarette paper, the mass fraction of the calcium carbonate is 28% to 40%.

[0034] More preferably, based on the mass of the cigarette paper, the mass fraction of the calcium carbonate is 30% to 35%.

[0035] The mass fraction of calcium carbonate is generally determined by the ash content of the finished paper after combustion.

[0036] Preferably, the rib strength of the cigarette paper is greater than 9.0%.

[0037] More preferably, the rib strength of the cigarette paper is greater than 10.5%.

[0038] The rib strength was tested using an ECMO IAS rib strength instrument.

[0039] The present invention also protects a method for preparing the cigarette paper, comprising the following steps: mixing pulp, calcium carbonate and an auxiliary agent to obtain a mixed pulp, and dehydrating, forming, pressing, embossing, sizing and drying the mixed pulp to obtain the cigarette paper; wherein, during embossing, the rib pressure is 20 to 120 kN / m.

[0040] Preferably, the ribbing pressure is 20-60 kN / m.

[0041] By using the calcium carbonate of the present invention to prepare cigarette paper, a higher rib strength can be achieved under a lower rib roller pressure, which is beneficial to prolonging the service life of the rubber-coated roller.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] The invention discloses a cigarette paper, which realizes a higher rib strength under a lower rib roller pressure by compounding liquid precipitated calcium carbonate and powder precipitated calcium carbonate with specific parameters, thereby increasing the service life of the rubber-coated roller. Moreover, the use of liquid precipitated calcium carbonate will not have a negative impact on other properties of the paper. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a scanning electron microscope image of the liquid precipitated calcium carbonate in Example 1 magnified 10,000 times.

[0045] Figure 2 This is a scanning electron microscope image of the powdered precipitated calcium carbonate in Comparative Example 1 magnified 10,000 times.

[0046] Figure 3 This is an appearance diagram of the cigarette paper of Example 1.

[0047] Figure 4 This is the appearance of the cigarette paper of Comparative Example 1. DETAILED DESCRIPTION

[0048] The present invention is further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0049] Liquid precipitated calcium carbonate, calcium carbonate satellite factory of China Tobacco Modi (Jiangmen) Paper Co., Ltd., the liquid precipitated calcium carbonate in each embodiment was obtained by customization / screening from the above factory.

[0050] Powdered precipitated calcium carbonate, Solvay Chemicals International SA, brand name Socal 92E.

[0051] The testing method for the length of the above-mentioned calcium carbonate single crystal is as follows: after photographing with a scanning electron microscope, the calcium carbonate single crystal in the photographed picture is analyzed and measured using NanoMeasuer software, with more than 50 single crystal length values ​​measured for each picture and more than 5 pictures measured for each sample; the above-mentioned data are analyzed using Origin software to obtain the range of single crystal length values.

[0052] The test method for the diameter of the above-mentioned calcium carbonate single crystal is as follows: after photographing with a scanning electron microscope, the calcium carbonate single crystal in the photographed picture is analyzed and measured using NanoMeasuer software, with more than 50 single crystal diameter values ​​measured for each picture and more than 5 pictures measured for each sample; the above-mentioned data are analyzed using Origin software to obtain the range of single crystal diameter values.

[0053] The testing method of the aspect ratio of the calcium carbonate single crystal is as follows: the aspect ratio is calculated using the single crystal length value and the single crystal diameter value obtained by the above measurement, and then analyzed using Origin software to obtain the single crystal aspect ratio range.

[0054] The D50 of the calcium carbonate polymer formed by the combination of the above calcium carbonate single crystals is tested by using a SediGraph III5120 sedimentation particle size analyzer.

[0055] Example 1

[0056] A cigarette paper is prepared from pulp, liquid precipitated calcium carbonate and an additive. The crystal form of the liquid precipitated calcium carbonate single crystal is spindle-shaped, the length of the liquid precipitated calcium carbonate single crystal is 1250-1443nm, the diameter of the liquid precipitated calcium carbonate single crystal is 204-257nm, and the aspect ratio of the liquid precipitated calcium carbonate single crystal is 5.3-6.1.

[0057] Several liquid-precipitated calcium carbonate single crystals combine to form calcium carbonate polymers, and the D50 of the polymer is 1.99 μm.

[0058] The preparation method of the cigarette paper comprises the following steps: mixing slurry, liquid precipitated calcium carbonate and an additive to obtain a mixed slurry, and dehydrating, forming, pressing, embossing, sizing and drying the mixed slurry to obtain the cigarette paper; wherein, during embossing, the rib pressure is 40 kN / m.

[0059] Example 2

[0060] A cigarette paper, which is different from Example 1 in that the preparation method of the cigarette paper is such that during embossing, the rib pressure is 35 kN / m.

[0061] Example 3

[0062] A cigarette paper, which is different from Example 1 in that: the crystal form of liquid precipitated calcium carbonate is spindle-shaped, the length of the liquid precipitated calcium carbonate single crystal is 1671-1839nm, the diameter of the liquid precipitated calcium carbonate single crystal is 241-289nm, and the aspect ratio of the liquid precipitated calcium carbonate single crystal is 6.2-7.0.

[0063] Several liquid-precipitated calcium carbonate single crystals combine to form calcium carbonate polymers, and the D50 of the polymer is 2.04 μm.

[0064] The rest is the same as Example 1.

[0065] Example 4

[0066] A cigarette paper, which is different from Example 1 in that: the crystal form of liquid precipitated calcium carbonate is spindle-shaped, the length of the liquid precipitated calcium carbonate single crystal is 1254-1447nm, the diameter of the liquid precipitated calcium carbonate single crystal is 244-290nm, and the aspect ratio of the liquid precipitated calcium carbonate single crystal is 4.5-5.2.

[0067] Several liquid-precipitated calcium carbonate single crystals combine to form calcium carbonate polymers, and the D50 of the polymer is 2.01 μm.

[0068] The rest is the same as Example 1.

[0069] Example 5

[0070] A cigarette paper is prepared from pulp, calcium carbonate and an additive. The calcium carbonate is a mixture of liquid precipitated calcium carbonate and powdered precipitated calcium carbonate. The crystal form of the liquid precipitated calcium carbonate single crystal is spindle-shaped. The length of the liquid precipitated calcium carbonate single crystal is 1250-1443nm. The diameter of the liquid precipitated calcium carbonate single crystal is 204-257nm. The aspect ratio of the liquid precipitated calcium carbonate single crystal is 5.3-6.1. Several liquid precipitated calcium carbonate single crystals are combined to form a calcium carbonate polymer, and the D50 of the polymer is 1.99μm.

[0071] The crystal form of the powder precipitated calcium carbonate single crystal is spindle-shaped, the length of the powder precipitated calcium carbonate single crystal is 901-1194nm, the diameter of the powder precipitated calcium carbonate single crystal is 364-425nm, and the aspect ratio of the powder precipitated calcium carbonate single crystal is 2.3-3.2. Several powder precipitated calcium carbonate single crystals are combined to form a calcium carbonate polymer, and the D50 of the polymer is 2.05μm.

[0072] The weight ratio of liquid precipitated calcium carbonate in calcium carbonate is 50%, and the weight ratio of powdered precipitated calcium carbonate in calcium carbonate is 50%.

[0073] The rest is the same as Example 1.

[0074] Example 6

[0075] A cigarette paper, which is different from Example 5 in that the weight ratio of liquid precipitated calcium carbonate in calcium carbonate is 10%, and the weight ratio of powdery precipitated calcium carbonate in calcium carbonate is 90%.

[0076] The rest is the same as Example 5.

[0077] Comparative Example 1

[0078] A cigarette paper is prepared from pulp, powdered precipitated calcium carbonate and an additive. The crystal form of the powdered precipitated calcium carbonate single crystal is spindle-shaped, the length of the powdered precipitated calcium carbonate single crystal is 901-1194nm, the diameter of the powdered precipitated calcium carbonate single crystal is 364-425nm, and the aspect ratio of the powdered precipitated calcium carbonate single crystal is 2.3-3.2.

[0079] Several powder-precipitated calcium carbonate single crystals are combined to form calcium carbonate polymers, and the D50 of the polymer is 2.05 μm.

[0080] The rest is the same as Example 1.

[0081] Comparative Example 2

[0082] A cigarette paper, which is different from Comparative Example 1 in that the preparation method of the cigarette paper is different from that of Comparative Example 1 in that the rib pressure during embossing is 100 kN / m.

[0083] The rest is the same as Comparative Example 1.

[0084] Comparative Example 3

[0085] A cigarette paper is prepared from pulp, liquid precipitated calcium carbonate and an additive. The crystal form of the liquid precipitated calcium carbonate single crystal is spindle-shaped, the length of the liquid precipitated calcium carbonate single crystal is 903-1201nm, the diameter of the liquid precipitated calcium carbonate single crystal is 366-431nm, and the aspect ratio of the liquid precipitated calcium carbonate single crystal is 2.3-3.2.

[0086] Several liquid-precipitated calcium carbonate single crystals combine to form calcium carbonate polymers, and the D50 of the polymer is 2.08 μm.

[0087] The rest is the same as Example 1.

[0088] Results

[0089] The cigarette papers of the above embodiments and comparative examples were tested by the following performance testing methods:

[0090] (1) Rib strength: tested using an EMCO IAS rib strength tester. The unit of rib strength is %.

[0091] (2) Paper ash content: measured in accordance with GB / T 742-2018.

[0092] (3) Paper weight: measured in accordance with GB / T 451.2-2023.

[0093] (4) Paper opacity: measured in accordance with GB / T 1543-2005.

[0094] (5) Service life of the rubber-coated roller: Comprehensively judged based on the uniformity, stability and clarity of the product ribs, and the same standard is used for all embodiments and comparative examples.

[0095] The specific test results are shown in Table 1 below:

[0096]

[0097] The appearance of the cigarette paper of Example 1 is as follows Figure 3 shown.

[0098] The appearance of the cigarette paper of Comparative Example 1 is as follows Figure 4 shown.

[0099] It can be seen from the above data that the cigarette paper of the present invention, through the compounding of liquid precipitated calcium carbonate and powder precipitated calcium carbonate with specific parameters, can also achieve a higher rib strength under a lower rib roller pressure, thereby increasing the service life of the rubber-coated roller. Under a rib roller pressure of 35 to 87 kN / m, the rib strength of the paper can be increased to 10.5 to 13.4%, and the service life of the rubber-coated roller can reach 116 to 144 hours. It can be seen from the opacity of the paper that the other properties of the cigarette paper of the present invention are stable, indicating that the present invention has no negative impact on the quality parameters of the cigarette paper.

[0100] From the examples and comparative example 1 and Figure 3 , Figure 4 It can be seen that the cigarette paper is made of powdered precipitated calcium carbonate. Under the pressure of the rib roller of 40 kN / m, the rib strength of the paper is only 6.8%, which is very low.

[0101] It can be seen from the embodiment, comparative example 1 and comparative example 2 that the cigarette paper is prepared by using powdered precipitated calcium carbonate. When the pressure of the rib roller is increased to 100 kN / m, the rib strength of the paper can only be increased to 10.3%, and the service life of the rubber-coated roller is greatly reduced to only 50 hours. Therefore, it is necessary to frequently stop the machine to replace the rubber-coated roller, which prolongs the downtime, significantly increases the production cost, and reduces the production efficiency.

[0102] It can be seen from the examples and comparative example 3 that although the cigarette paper is also prepared by using liquid precipitated calcium carbonate, the single crystal length of the liquid precipitated calcium carbonate, the single crystal diameter of the liquid precipitated calcium carbonate and the aspect ratio of the liquid precipitated calcium carbonate are different from those in the examples. Under the pressure of the rib roller of 40 kN / m, the rib strength of the paper can only be increased to 8.9%, which cannot meet the requirements.

[0103] It can be seen from Examples 1, 3 and 4 that the length of the liquid precipitated calcium carbonate single crystal is 1250-1500 nm, and the aspect ratio of the liquid precipitated calcium carbonate single crystal is 5.3-6.1, which is more conducive to improving the rib strength.

[0104] It can be seen from Example 1, Example 5 and Example 6 that the weight ratio of the liquid precipitated calcium carbonate in the calcium carbonate is 50% to 100%, which is more conducive to improving the rib strength.

[0105] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A cigarette paper, characterized in that: The invention is prepared from slurry, calcium carbonate and an auxiliary agent, wherein the calcium carbonate is a mixture of liquid precipitated calcium carbonate and powder precipitated calcium carbonate, the crystal form of the liquid precipitated calcium carbonate single crystal is spindle-shaped, the length of the liquid precipitated calcium carbonate single crystal is 1200-1850nm, the diameter of the liquid precipitated calcium carbonate single crystal is 200-290nm, and the aspect ratio of the liquid precipitated calcium carbonate single crystal is 4.5-7.0; The weight ratio of the liquid precipitated calcium carbonate in the calcium carbonate is 10% to 100%.

2. The cigarette paper according to claim 1, characterized in that: In the cigarette paper, a number of the liquid-precipitated calcium carbonate single crystals are combined to form calcium carbonate polymers, and the D50 of the polymers is 1.6 to 2.2 μm.

3. The cigarette paper according to claim 1, characterized in that: The length of the liquid precipitated calcium carbonate single crystal is 1250-1500nm.

4. The cigarette paper according to claim 1, characterized in that: The aspect ratio of the liquid precipitated calcium carbonate single crystal is 5.3 to 6.

1.

5. The cigarette paper according to claim 1, characterized in that: The weight ratio of the liquid precipitated calcium carbonate in the calcium carbonate is 50% to 100%.

6. The cigarette paper according to claim 1, characterized in that: The crystal form of the powder precipitated calcium carbonate single crystal is spindle-shaped, the length of the powder precipitated calcium carbonate single crystal is 901-1194 nm, the diameter of the powder precipitated calcium carbonate single crystal is 364-425 nm, and the aspect ratio of the powder precipitated calcium carbonate single crystal is 2.3-3.

2.

7. The cigarette paper according to claim 1, characterized in that: Calculated based on the mass of the cigarette paper, the mass fraction of the calcium carbonate is 28% to 40%.

8. The cigarette paper according to claim 1, characterized in that: The rib strength of the cigarette paper is greater than 9.0%.

9. The method for preparing cigarette paper according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: mixing pulp, calcium carbonate and an auxiliary agent to obtain a mixed pulp, and dehydrating, forming, pressing, embossing, sizing and drying the mixed pulp to obtain the cigarette paper; wherein, during embossing, the rib pressure is 20-120 kN / m.

10. The method for preparing cigarette paper according to claim 9, characterized in that: The ribbing pressure is 20~60kN / m.

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