High-softness high-wet-strength facial tissue base paper and preparation method thereof

Abstract

The invention discloses high-softness high-wet-strength face tissue base paper and a preparation method thereof, and the preparation method comprises the following steps: (1) dispersing softwood pulp, mixing with hardwood pulp, and grinding; (2) mixing softwood pulp with broken paper, and then grinding; and (3) mixing the pulp ground in the step (1) and the step (2) with hardwood pulp, adding a wet strength agent and a cationic softening agent, uniformly mixing, feeding into a paper machine net part, forming, squeezing, drying, wrinkling with a scraper, and curling to obtain the body paper. According to the invention, long and short fibers are mixed according to a ratio and subjected to pulp grinding treatment, a softening agent is added to the interior and the surface, and an alloy scraper is used, so that the raw paper has dry strength, wet strength and smooth and soft properties, and meanwhile, the problems of rough hand feeling, wet water fracture, paper surface linting and the like are avoided.

Description

Technical Field

[0001] The invention relates to the technical field of facial tissue papermaking, and in particular to a facial tissue base paper with high softness and high wet strength and a preparation method thereof. Background Art

[0002] Facial tissue is a thin and soft product made of pulp or paper, which is usually used for cleaning purposes such as wiping, wiping hands and mouth. It is usually rectangular or square in shape, absorbent and comfortable to provide effective cleaning and absorption functions. Paper towels are widely used in daily life and public places, and can exist in various forms. Its light and easy-to-carry characteristics make it a convenient tool for people to stay clean and hygienic in various situations. Compared with toilet paper, facial tissue is tougher, softer and more comfortable when fully wetted. Due to its special usage conditions, the requirements for the base paper are higher. It needs to absorb water quickly when wiping, and at the same time has comfortable softness and high wet strength that is not easy to break.

[0003] The existing base paper making technology uses bagasse, straw pulp, bamboo pulp or wood pulp and adds chemicals, but most of the base papers cannot take into account the water breakage and hand comfort, which is not conducive to wiping key parts such as the face. Summary of the invention

[0004] Purpose of the invention: The first purpose of the present invention is to provide a method for preparing a high-softness and high-wet-strength facial tissue base paper; the second purpose of the present invention is to provide the base paper prepared by the method.

[0005] Technical solution: The method for preparing the high-softness and high-wet-strength facial tissue base paper of the present invention comprises the following steps:

[0006] (1) mixing coniferous wood pulp with hardwood wood pulp in a mass ratio of (2-4):(6-8), and then refining the pulp until the pulp freeness reaches 350-450 csf;

[0007] (2) mixing coniferous wood pulp and broke paper in a mass ratio of (2-4):(6-8), and then refining the pulp until the pulp freeness reaches 220-350 csf;

[0008] (3) The pulp after refining in step (1) and step (2) is mixed with hardwood pulp in a mass ratio of 2-3:2-3:4-6, a wet strength agent and a softener are added and mixed evenly, and the mixture is sent to a paper machine wire section for forming, pressing, drying, scraper wrinkling, and curling to obtain the base paper; wherein the softener is added to the surface of the drying cylinder during the drying process.

[0009] Preferably, in step (1), the refining adopts a 1+2 two-stage refiner, the first stage refining power is 70-80kw / t, and the second stage two refiners are connected in parallel, and the refining power is 40-50kwh / t.

[0010] Preferably, in step (2), the refining power is 120-140 kw / t.

[0011] Coniferous wood and hardwood pulp are the main raw materials. Compared with bamboo pulp or sugarcane pulp, wood pulp fiber has better strength and smoothness and softness. Refining can make the fiber filaments broom finer fiber bundles, making the fiber softer, but it cannot be over-refined, which can easily cause fiber breakage. After continuous experiments, it was found that the pipeline wet pulp (short fiber) and long fiber were mixed together. After entering the refining section, the long and short fibers were rubbed against each other, and the 1+2 two-stage refiner "light knife fine grinding" method was adopted. The first section was mainly relieved (refining power 70~80kwh / t), and the second section two refiners were connected in parallel, supplemented by light knife brooming (refining power 40~50kwh / t), so that the fiber was fully filamented and broomed to increase the hydrogen bonding between the fibers, thereby enhancing the strength of the paper, while improving the fiber softness and reducing the TS7 value.

[0012] In step (1), the coniferous wood pulp is mixed with the broadleaf wood pulp in a mass ratio of (2-4):(6-8) after being dispersed, so as to effectively utilize the different fiber properties of long and short fibers and make the fibers more fibrillated under the "light knife fine grinding" refining method of the 1+2 two-stage refiner.

[0013] In step (2), coniferous wood pulp and broken paper are mixed in a mass ratio of (2-4):(6-8), and medium-to-high power refining is performed to reduce the loss of fiber tensile strength while ensuring effective decomposition of the broken paper.

[0014] The softener is a cationic softener.

[0015] Preferably, in step (3), the amount of the cationic softener mixed with the wet strength agent is 2.5±0.5 kg / t.

[0016] Preferably, in step (3), the amount of softener added to the surface of the drying cylinder is 1.5±0.5 kg / t.

[0017] Preferably, the wet strength agent is used in an amount of 45±5 kg / t.

[0018] Preferably, the scraper for scraper wrinkling adopts a 15° alloy steel blade with a service life of ≤1 million meters / blade.

[0019] A high-softness and high-wet-strength facial tissue base paper is prepared by the preparation method of the present invention, and the HF of the base paper is greater than 78. HF is Hand Feel softness.

[0020] In order to meet the requirements, it is necessary to reduce TS7 (softness of the fiber) and TS750 (Roughness).

[0021] Invention mechanism:

[0022] TS750 (Roughness) represents the smoothness of the base paper surface, which is mainly affected by fine wrinkles and the connection between fibers. Therefore, in order to control the pulping effect of the pulp, the present invention uses the special structure of long fiber, supplemented by "mixed pulping" and "light knife fine grinding" to adjust, and at the same time, softeners are added to improve the softness of the base paper.

[0023] In the present invention, coniferous wood and broadleaf wood pulp are the main raw materials. Compared with bamboo pulp or sugarcane pulp fiber, wood pulp fiber has better strength and smoothness and softness. Through the mixed pulping treatment of broadleaf wood and coniferous wood fibers, more fiber fibrillation is obtained, and the fiber fibrillation is finer. The fiber bundles are made softer and have better tensile strength. The base paper has higher dry strength.

[0024] Paper is a fibrous porous material, the main components of which are cellulose, hemicellulose and lignin. The structure of cellulose is a spiral fiber structure with staggered hydroxyl hydrogen bonds. This extensive hydrogen bond between fibers gives paper strength and rigidity. Properly limiting or reducing this intermolecular hydrogen bond can make paper softer. The softener added to the pulp will adsorb on the fiber surface, forming a layer of film with hydrophobic bases neatly arranged outward, reducing the friction between the fibers and making it easy for the fibers to slide against each other, thus producing a softening effect. Due to the lipophilicity of the hydrophobic base, the friction coefficient is greatly reduced. When the human body contacts the fiber, the friction resistance between the fiber and the human body decreases, thereby obtaining a better feel. In addition, because the softener can interfere with the hydrogen bond association between paper fibers, it softens the paper, making the paper fluffy and plump, and producing a soft feel. We chose a cationic softener, because the cationic softener can be strongly adsorbed on the fiber surface by electrostatic attraction (because the paper fiber is negatively charged in water), which greatly reduces the surface energy. Moreover, they are adsorbed on the fiber with polar groups, and their lipophilic groups face the air, which can reduce the fiber surface energy and the friction coefficient of the fiber. The advantage of cationic softener is that under the same amount of conditions, its softening effect is better than other softeners, and it also has a killing and mildew-proofing effect. Since softeners reduce the intermolecular bonding force of paper fibers, making them easy to break under external forces, excessive addition will affect the tensile strength and wet strength of the base paper, causing the base paper to break due to insufficient tensile strength, or the wet tensile force cannot meet the physical property requirements. Therefore, when using cationic softener, control its addition amount to ensure that the hand feel is satisfied while reducing the impact on tensile strength and wet strength.

[0025] In order to improve the feel of base paper, in addition to adding softener into the pulp, a surface softener is also sprayed on the surface of the base paper. When using a cationic fatty acid ester softener on the surface of the base paper, the hydrophilic group of the softener molecule is adsorbed on the fiber, the hydrophobic group is arranged outward, and the fiber is covered by a long-chain fatty alkyl film. Therefore, the fiber treated with this type of softener is soft, and the surface of the paper is also smooth, and it has a strong bonding force with various fibers. After use, the paper can obtain an excellent softening effect. If added excessively, it will affect the coating, increase the peeling of the base paper, and cause abnormal paper floating on the base paper, affecting normal production, so the dosage should be controlled.

[0026] In addition, a 15° alloy steel knife is used to control its service life (1 million meters) to ensure delicate wrinkles on the surface; at the same time, a surface softener is added to the de-cylinder agent to achieve a soft and smooth effect by changing the arrangement of fibers.

[0027] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: by using long and short fibers mixed in proportion for pulping, reasonable fiber ratio, appropriate amount of chemical addition and alloy scraper, the base paper has both dry strength, wet strength and smoothness and softness, while avoiding the problems of rough hand feel, water cracking, and hair loss on the paper surface, and can meet the needs of people for wiping key parts such as the face. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a schematic diagram of a crescent forming paper machine;

[0029] Figure 2 Schematic diagram of the production process. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is further described below in conjunction with embodiments.

[0031] Example 1

[0032] The method for preparing the high-softness and high-wet-strength facial tissue base paper of the present invention comprises the following steps:

[0033] (1) 100% softwood pulp is sent to the N1 line pulping machine. After pulping, it is stored in the middle tank, and then mixed with hardwood pulp (pipeline wet pulp) at a mass ratio of 3:7 and sent to the N1 discharge tower. After being processed by a 1+2 two-stage refiner (first stage 70kw / t, second stage 40kw / t), the pulp freeness is 427csf, and the pulp is stored in the N1 post-refining tower;

[0034] (2) 100% softwood pulp and broke paper were dispersed in a mass ratio of 3:7, and then sent to the N2 unloading tower. After being processed by four pulping machines (total pulping power of 120 kW / t), the pulp freeness was 335 csf, and the pulp was stored in the N2 post-knock tower;

[0035] (3) After passing through the N1 line, N2 line and pipeline wet pulp with a ratio of 3:3:4, 43kg / ton of wet strength agent (FH-P150 - Zhangzhou Fuhe) and 3kg / ton of internal softener SF8866 - Liangshi are added and mixed evenly, and then sent to the paper machine mesh section for forming, pressing and drying. At the same time, 2.0kg / ton of surface softener SF8866 - Liangshi is added to the surface of the drying cylinder (drying section), and then a 15° alloy steel knife (life ≤ 1 million meters / knife) is used for scraping and curling to obtain facial tissue base paper with smooth and soft feel and wet water breakage.

[0036] The softener SF8866-Liangshi was purchased from Guangdong Liangshi Industrial Materials Co., Ltd., and the wet strength agent FH-P150-Zhangzhou Fuhe was purchased from Zhangzhou Fuhe Applied Materials Technology Co., Ltd.

[0037] Example 2

[0038] The method for preparing the high-softness and high-wet-strength facial tissue base paper of the present invention comprises the following steps:

[0039] (1) 100% softwood pulp is fed into the N1 line pulping machine. After pulping, it is stored in the middle tank, and then mixed with hardwood pulp (pipeline wet pulp) at a mass ratio of 3:7 and fed into the N1 discharge tower. After being processed by a 1+2 two-stage pulping machine (first stage 80kw / t, second stage 50kw / t), the pulp freeness is 364csf, and the pulp is stored in the N1 post-refining tower;

[0040] (2) 100% softwood pulp and broke paper were dispersed in a mass ratio of 3:7, and then sent to the N2 unloading tower. After being processed by four pulping machines (total pulping power of 140 kW / t), the pulp freeness was 238 csf, and the pulp was stored in the N2 post-knock tower;

[0041] (3) After passing through the N1 line, N2 line and pipeline wet pulp with a ratio of 3:3:4, 42 kg / ton of wet strength agent (FH-P150 - Zhangzhou Fuhe) and 3.0 kg / ton of internal softener SF8866 - Liangshi are mixed evenly and sent to the paper machine wire section for forming, pressing and drying. At the same time, 2.0 kg / ton of surface softener SF8866 - Liangshi is added to the surface of the drying cylinder (drying section). Then, a 15° alloy steel knife (lifespan ≤ 1 million meters / knife) is used for scraping and wrinkling to obtain a facial tissue base paper with a smooth and soft feel and wet water breakage.

[0042] Example 3

[0043] (1) 100% softwood pulp is sent to the N1 line pulping machine. After pulping, it is stored in the middle tank, and then mixed with hardwood pulp (pipeline wet pulp) at a mass ratio of 4:6 and sent to the N1 discharge tower. After being processed by a 1+2 two-stage refiner (first stage 70kw / t, second stage 40kw / t), the pulp freeness is 433csf, and the pulp is stored in the N1 post-refining tower;

[0044] (2) 100% softwood pulp and broke paper were dispersed in a mass ratio of 4:6, and then sent to the N2 unloading tower. After being processed by four pulping machines (total pulping power of 120 kW / t), the pulp freeness was 326 csf, and the pulp was stored in the N2 post-knock tower;

[0045] (3) After passing through the N1 line, N2 line and pipeline wet pulp with a ratio of 3:3:4, 43kg / ton of wet strength agent (FH-P150-Zhangzhou Fuhe) and 2.0kg / ton of internal softener SF8866-Liangshi were added and mixed evenly, and then sent to the paper machine wire section for forming, pressing and drying. At the same time, 1.0kg / ton of surface softener SF8866-Liangshi was added to the surface of the drying cylinder (drying section). Then, a 15° alloy steel knife (life ≤ 1 million meters / knife) was used for scraping and curling to obtain facial tissue base paper with smooth and soft feel and wet water breakage.

[0046] Comparative Example 1

[0047] (1) 100% softwood pulp is sent to the N1 line pulping machine. After pulping, it is stored in the middle tank, and then mixed with hardwood pulp (pipeline wet pulp) at a mass ratio of 3:7 and sent to the N1 discharge tower. After being processed by a 1+1 two-stage refiner (refining power 140kw / t), the pulp freeness is 332csf, and the pulp is stored in the N1 post-reduction tower;

[0048] (2) 100% softwood pulp and broke paper were dispersed in a mass ratio of 3:7, and then sent to the N2 unloading tower. After being processed by four pulping machines (total pulping power of 120 kW / t), the pulp freeness was 227 csf, and the pulp was stored in the N2 post-knock tower;

[0049] (3) After passing through the N1 line, N2 line and pipeline wet pulp with a ratio of 3:3:4, 43kg / ton of wet strength agent (FH-P150-Zhangzhou Fuhe) and 3.0kg / ton of internal softener SF8866-Liangshi were added and mixed evenly, and then sent to the paper machine wire section for forming, pressing and drying. At the same time, 2.0kg / ton of surface softener SF8866-Liangshi was added to the surface of the drying cylinder (drying section). Then, a 15° alloy steel knife (life ≤ 1 million meters / knife) was used for scraping and curling to obtain a facial tissue base paper with a smooth and soft feel and wet water breakage.

[0050] Comparative Example 2

[0051] (1) 100% softwood pulp is sent to the N1 line pulping machine. After pulping, it is stored in the middle tank, and then mixed with hardwood pulp (pipeline wet pulp) at a mass ratio of 3:7 and sent to the N1 discharge tower. After being processed by a 1+2 two-stage pulping machine (first stage 70, second stage 40kw / t), the pulp freeness is 427csf, and the pulp is stored in the N1 post-refining tower;

[0052] (2) 100% softwood pulp and broke paper were dispersed in a mass ratio of 3:7, and then sent to the N2 unloading tower. After being processed by four pulping machines (total pulping power of 120 kW / t), the pulp freeness was 335 csf, and the pulp was stored in the N2 post-knock tower;

[0053] (3) After passing through the N1 line, N2 line and pipeline wet pulp with a ratio of 3:3:4, 43kg / ton of wet strength agent (FH-P150 - Zhangzhou Fuhe) and 5.0kg / ton of softener SF8866 - Liangshi are added and mixed evenly, and then sent to the paper machine mesh for forming, pressing and drying. Then, a 15° alloy steel knife (lifespan ≤ 1 million meters / knife) is used for scraping and curling to obtain facial tissue base paper with smooth and soft feel and wet water breakage.

[0054] Performance Testing

[0055] The TSA comprehensive hand feel data of the above embodiments and comparative examples were tested.

[0056] TSA comprehensive hand feel data test:

[0057] 1. Cutting sample size:

[0058] 2. Test the smoothness / roughness, softness, stiffness and hand feel (HF-Facial III) according to the TSA fabric hand / tactile tester (EMTEC, Germany).

[0059] The test results are shown in Table 1.

[0060]

[0061] As can be seen from Table 1, the base paper prepared in Examples 1 to 3 takes into account both the smooth and soft feel of the base paper and the wet water breakage. It can be seen from the data of Examples 1-3 that when the refining power is increased, the pulp shear is more, the freeness decreases, the TS7 softness increases, and the HF affecting the hand feel decreases; it can be seen from Examples 1 and 3 that when the amount of softener is reduced, the TS7 softness and TS750 increase, and the HF affecting the hand feel decreases, but from the test data of Examples 1 to 3, it can be seen that the hand feel requirements can be met. The base paper prepared in Examples 1 to 3 takes into account both the smooth and soft feel of the base paper and the wet water breakage.

[0062] The HF value of the comprehensive feel of Comparative Example 1 is lower than that of Example 1. This is because the 1+2 "light knife fine grinding" refining method is not adopted, but the conventional 1+1 high-power refining is used. Excessive refining aggravates fiber breakage and affects the feel of the base paper.

[0063] The overall hand feel of Comparative Example 2 is not much different from that of Example 1. From the process point of view, the same amount of softener is added to the system, and the softener can interfere with the hydrogen bond association between paper fibers, thereby softening the paper sheet, making the paper sheet fluffy and full, and producing a soft hand feel. The difference between the two lies in the surface smoothness (TS750). Since the surface softener can also promote the smoothness of the paper surface, the surface smoothness of Example 1 is better than that of Comparative Example 2.

Claims

1. A method for preparing a high-softness and high-wet-strength facial tissue base paper, characterized in that: The following steps are involved: (1) mixing coniferous wood pulp with hardwood wood pulp in a mass ratio of (2-4):(6-8), and then refining the pulp until the pulp freeness reaches 350-450 csf; (2) mixing coniferous wood pulp and broke paper in a mass ratio of (2-4):(6-8), and then refining the pulp until the pulp freeness reaches 220-350 csf; (3) The pulp after refining in step (1) and step (2) is mixed with hardwood pulp in a mass ratio of (2-3): (2-3): (4-6), a wet strength agent and a softener are added and mixed evenly, and the mixture is sent to a paper machine wire section for forming, pressing, drying, scraper wrinkling, and curling to obtain the base paper; wherein the softener is added to the surface of the drying cylinder during the drying process.

2. The method for preparing high-softness and high-wet-strength facial tissue base paper according to claim 1, characterized in that: In step (1), the pulping is performed using a 1+2 two-stage pulping machine, the first stage pulping power is 70-80kw / t, and the second stage two pulping machines are connected in parallel, and the pulping power is 40-50kwh / t.

3. The method for preparing high-softness and high-wet-strength facial tissue base paper according to claim 1, characterized in that: In step (2), the refining power is 120-140 kw / t.

4. The method for preparing high-softness and high-wet-strength facial tissue base paper according to claim 1, characterized in that: The softener is a cationic softener.

5. The method for preparing high-softness and high-wet-strength facial tissue base paper according to claim 1, characterized in that: In the step (3), the amount of the softener mixed with the wet strength agent is 2.5±0.5 kg / t.

6. The method for preparing high-softness and high-wet-strength facial tissue base paper according to claim 1, characterized in that: In the step (3), the amount of softener added to the surface of the drying cylinder is 1.5±0.5 kg / t.

7. The method for preparing high-softness and high-wet-strength facial tissue base paper according to claim 1, characterized in that: The wet strength agent is used in an amount of 45±5 kg / t.

8. The method for preparing high-softness and high-wet-strength facial tissue base paper according to claim 1, characterized in that: The scraper for scraper wrinkling is made of 15° alloy steel blade, and the service life is ≤ 1 million meters / blade.

9. A high softness and high wet strength facial tissue base paper, characterized in that: The base paper is prepared by the method according to any one of claims 1 to 8, and the HF of the base paper is greater than 78.

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