Production method for reducing proportion of long fibers of cream base paper

Abstract

The invention discloses a production method for reducing the proportion of long fibers of cream base paper, and belongs to the field of papermaking. The main technical scheme is as follows: raw materials comprise long fibers (one or more of cotton pulp, softwood pulp and bamboo pulp which are subjected to repulping and are ground by two serially connected disc mills until the beating degree is 25-35 degrees SR and the wet weight is 8.0-13.0 g), short fibers (hardwood pulp which is subjected to repulping and defibering and the beating degree is 15-20 degrees SR) and broken paper (subjected to repulping and defibering); adjusting the flow, mixing the three components according to the mass ratio of (8-20): (85-70): (15-0) in a pulp preparation pool, and uniformly grinding until the beating degree is 25-45 degrees SR; the white water reflux quantity is regulated and controlled in the process. And after the slurry is formed by a high-speed paper machine, wrinkling by using a ceramic or carbon steel scraper under the dryness of 55-85% at the wrinkling rate of 18-25%, and coiling and slitting to obtain the cream base paper. The quantification of the raw paper is 10-20g / m < 2 >, and the transverse dry tensile index is gt; 3.0 N.m / g, and the longitudinal wet tensile index gt; 3.0 N.m / g, and the softness lt; the bulk is gt; 6.60 m < 3 > / g, and the transverse liquid absorption height gt; and 75 mm / (100s). The process is optimized, the use amount of long fibers is remarkably reduced, meanwhile, it is ensured that the cream base paper has excellent strength and bearing performance, and the cost is remarkably reduced.

Description

Technical Field

[0001] This invention belongs to the field of papermaking and relates to a production method for reducing the long fiber ratio of emulsion base paper. Background Technology

[0002] Toilet paper is designed and manufactured to meet the specific application needs of segmented markets. Generally, absorbency, softness, strength (dry / wet), and bulk are the core indicators for evaluating toilet paper performance. The performance of toilet paper depends on the properties of the fibers themselves, chemical additives, and papermaking technology. Toilet paper is primarily produced from short fibers (such as hardwood), with a certain proportion of long fibers (such as cotton pulp, bamboo pulp, and softwood pulp) added to give the paper strength and running performance during papermaking. Depending on the type of paper, there will be specific short and long fiber ratio formulations. A higher proportion of short fibers will improve softness, while adding long fibers will increase wet and dry strength but decrease softness. Mild beating can improve the properties of the virgin fibers, but as the degree of beating increases, the bulk and absorbency of the paper will decrease.

[0003] Cream-coated paper is a type of toilet paper formed by coating or spraying cream onto the surface of base paper. It has an excellent soft touch and long-lasting moisturizing properties, thus standing out from conventional household paper products. Among them, the fiber raw material characteristics and papermaking process of the base paper, as the underlying foundation for paper functionalization, have a decisive influence on the performance of the final cream-coated paper product.

[0004] For cream paper, achieving the same degree of freeness, low-load freeing can construct a loose, porous network structure through high fibrillation rate and retained fiber length, giving cream paper excellent moisture retention. However, its low fine fiber content and low fiber cut rate lead to insufficient mechanical entanglement between fibers, becoming a bottleneck for wet strength. Therefore, within the recommended freeing range, introducing a wet strength agent in conjunction with a short fiber system can be the key to solving this problem. The white water circulation system needs to be strengthened in the existing process. By adjusting the flow rates of long fibers, short fibers, and waste paper, as well as the white water return flow rate, the fibers in the pulp tank can retain the long fiber skeleton (avoiding over-refining) while constructing a dense wet reinforcing phase, achieving a synergistic leap in moisture retention and wet strength. Summary of the Invention

[0005] In view of this, the present invention provides a production method for reducing the long fiber ratio of cream base paper. Based on fiber characteristics and conventional high-speed crescent paper machine technology, improvements are proposed to reduce the amount of long fibers used in the production process while achieving the key performance of the standard cream paper.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for producing a paper with a reduced long fiber ratio in cream-based paper, characterized by comprising the following steps:

[0008] (1) Long fibers are fed into a long fiber hydraulic pulper for disintegration, then pumped into the long fiber pre-beating pulp tank, passed through a refiner, and then pumped into the long fiber post-beating pulp tank. The degree of disintegration of the pulp after long fiber beating is 25-35°SR, and the wet weight is 8.0-13.0g.

[0009] (2) Short fibers are fed into a short fiber hydraulic pulper for disintegration, and then pumped into the short fiber pre-pulping tank. After passing through a descaling machine, they are then pumped into the short fiber post-pulping tank. The degree of disintegration of the pulp after short fiber disintegration is 15-20°SR.

[0010] (3) The waste paper is fed into the pulper for crushing, then pumped into the waste paper pulp tank, passed through the desoldering machine, and then pumped into the waste paper pulp tower;

[0011] (4) Adjust the flow rates of long fiber after knocking, short fiber after knocking and waste pulp so that they are pumped into the mixing tank in proportion, and after passing through the leveling mill, they are then pumped into the pulping tank.

[0012] (5) The pulp is pumped to the headbox and then enters the tissue paper machine for forming, pressing and drying;

[0013] (6) The paper sheets dried to a semi-dry state by air hood and drying cylinder are wrinkled with a doctor blade at a dryness of 55-85% and a wrinkling rate of 18-25%. Then, they are wound and cut to obtain cream base paper.

[0014] (7) Wherein, the physical properties (converted to single layer) of the cream base paper produced by the manufacturing method reach a basis weight of 10-20 g / m². 2 Longitudinal dry tensile index > 7.0 N·m / g, transverse dry tensile index > 3.0 N·m / g, longitudinal wet tensile index > 3.0 N·m / g, softness < 95 mN, bulk > 6.60 m 3 / g, lateral liquid aspiration height >75mm / (100s).

[0015] Preferably, the long fibers are one or more of cotton pulp, softwood pulp, and bamboo pulp; the pulping machine is two tandem disc mills.

[0016] Preferably, the short fiber is hardwood pulp.

[0017] Preferably, the ratio of long fiber knockout, short fiber knockout, and waste paper mass in the pulp mixing tank is (8-20):(85-70):(15-0), and the white water return flow rate is adjusted during pulping and mixing.

[0018] Preferably, in step (4), the slurry dissolution degree of the slurry in the slurry forming tank is 25-45°SR.

[0019] Preferably, the added wet-end chemicals include, but are not limited to, bactericides, softeners, and wet strength agents.

[0020] Preferably, the wet strength agent is polyamide epichlorohydrin resin (i.e., PAE).

[0021] Preferably, in step (6), the scraper is made of ceramic or carbon steel and the wrinkling angle is 15-35°.

[0022] A cream-based paper, characterized in that it is produced by any one of the above-mentioned production methods.

[0023] The physical properties (converted to single-layer) of the cream base paper reach a basis weight of 10-20 g / m². 2 Longitudinal dry tensile index > 7.0 N·m / g, transverse dry tensile index > 3.0 N·m / g, longitudinal wet tensile index > 3.0 N·m / g, softness < 95 mN, bulk > 6.60 m 3 / g, lateral liquid aspiration height >75mm / (100s).

[0024] As can be seen from the above technical solution, compared with the prior art, this invention discloses a production method for reducing the long fiber ratio of cream-based paper, which has the following beneficial effects: low-load pulping constructs a loose and porous paper skeleton through high flocculentization rate and low fiber cutting rate, replacing the supporting role of traditional long fibers and laying the foundation for moisture retention; by adjusting the pulping flow rate and white water return flow rate, the content of fine fibers in the pulping tank is increased, and wet strength agents are used to synergistically bond short fiber fragments to form a high-strength reinforcing network. This process reduces the wrinkling rate while maintaining the basis weight and moisture retention of the paper, resulting in a smooth, delicate cream-based paper with a more uniform fiber network structure. This facilitates the uniform penetration and adhesion of more cream on the paper surface, ultimately achieving improved moisture retention and strength of the cream-based paper while reducing the long fiber ratio. It breaks through the production bottleneck of traditional high long fiber dependence, significantly improving economic benefits. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0026] To better compare the moisturizing properties of the corresponding cream paper, the basis weight of both the standard cream paper and the cream paper of the present invention was 14.0 ± 0.5 g / m³. 2 The amount of cream added was 2.5±0.2g / m³. 2 The cream used in the examples was the same, and the roller coating conditions were identical. (See attached image.) Figure 1The moisturizing properties of the cream paper produced by the method of the present invention are clearly demonstrated. Specifically, when the cream paper is dried in an oven at 60°C for 1, 2, and 3 hours, the moisturizing properties of the cream paper in the examples are all higher than those of the standard cream paper. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] The fine fiber content and total fiber fibrillation rate of the cream base paper were determined according to GB / T 29779-2013 and GB / T 22836-2008, respectively.

[0029] The moisturizing properties of the cream paper were tested by drying it in a 60℃ oven for 1, 2, and 3 hours respectively. It was then placed in a desiccator, cooled to room temperature, and weighed. The calculations for moisturizing properties and the amount of cream added are shown in the following formulas.

[0030]

[0031] Cream addition amount = Cream paper mass - Base paper mass

[0032] Example 1

[0033] (1) Moon brand softwood pulp is put into a long fiber hydraulic pulper for pulping, and then pumped into the long fiber pre-pulping tank. It is then ground by a single disc mill with a power setting of 75kwh / t. After that, it is pumped into the long fiber post-pulping tank. The pulp after long fiber pulping has a freeness of 30°SR and a wet weight of 8.0g.

[0034] (2) Goldfish brand commercial hardwood pulp is put into a short fiber hydraulic pulper for pulping, then pumped into the short fiber pre-pulping tank, and after passing through a desolvator, it is pumped into the short fiber post-pulping tank. The degree of dissolution of the pulp after short fiber pulping is 18°SR.

[0035] (3) The waste paper is fed into the pulper for crushing, then pumped into the waste paper pulp tank, passed through the desoldering machine, and then pumped into the waste paper pulp tower;

[0036] (4) The ratio of the flow rate of the long fiber pulp, the short fiber pulp, and the waste pulp is set at 20:70:10. The pulp is pumped into the mixing tank, and after passing through the leveling mill, the power is set at 30kwh / t. Then it is pumped into the pulping tank. The pulp in the pulping tank has a beating degree of 43°SR. The added wet end chemicals include PAE type wet strength agent 1# with a solid content of 12.5% ​​and an addition amount of 20kg / t.

[0037] (5) The pulp is pumped to the headbox and then enters the tissue paper machine for forming, pressing and drying. The paper sheet dried to 65% dryness by the air hood and Yankee drying cylinder is creped by a carbon steel doctor blade that is closely attached to the surface of the drying cylinder. The creping angle is set to 25°. Then it is wound and slit to obtain cream base paper.

[0038] (6) The crease rate of the fabricated base paper is 24%, the fine fiber content is 14%, and the total fiber crease rate is 3.8%.

[0039] Example 2

[0040] (1) Hongyu brand softwood pulp is fed into a long fiber hydraulic pulper for pulping, and then pumped into the long fiber pre-pulping tank. After passing through two series-run disc mills with a power of 40kwh / t, it is then pumped into the long fiber post-pulping tank. The pulp after long fiber pulping has a beating degree of 25°SR and a wet weight of 8.5g.

[0041] (2) Goldfish brand hardwood pulp is fed into a short fiber hydraulic pulper for pulping, then pumped into the short fiber pre-pulping tank, passed through a de-splitting machine, and then pumped into the short fiber post-pulping tank. The degree of dissociation of the pulp after short fiber dissociation is 17°SR.

[0042] (3) The waste paper is fed into the pulper for crushing, then pumped into the waste paper pulp tank, passed through the desoldering machine, and then pumped into the waste paper pulp tower;

[0043] (4) The ratio of the flow rate of the long fiber pulp after knocking, the short fiber pulp after knocking, and the pulp of the waste pulp is set at 10:75:15. The pulp is pumped into the mixing tank, and after passing through the leveling mill, the power is set at 20kwh / t. Then it is pumped into the pulping tank. The pulp in the pulping tank has a knocking degree of 35°SR. The added wet end chemicals include PAE type low chlorine wet strength agent 2# with a solid content of 15.0% and an addition amount of 15kg / t.

[0044] (5) The pulp is pumped to the headbox and then enters the tissue paper machine for forming, pressing and drying. The paper sheet dried to 80% dryness by the air hood and Yankee drying cylinder is creped by a carbon steel doctor blade that is closely attached to the surface of the drying cylinder. The creping angle is set to 20°. Then it is wound and slit to obtain the cream base paper.

[0045] (6) The crease rate of the fabricated base paper is 18%, the fine fiber content is 10%, and the total fiber crease rate is 3.3%.

[0046] Example 3

[0047] (1) Bas brand commercial bamboo pulp and Yongfeng brand commercial softwood pulp were fed into a long fiber hydraulic pulper at a ratio of 2:1 for pulping, and then pumped into the long fiber pre-pulping tank. After passing through two series-connected disc mills with power settings of 40kwh / t and 35kwh / t respectively, the pulp was then pumped into the long fiber post-pulping tank. The pulp after long fiber pulping had a beating degree of 28°SR and a wet weight of 9.0g.

[0048] (2) Goldfish FSC brand commercial hardwood pulp is put into a short fiber hydraulic pulper for pulping, then pumped into the short fiber pre-pulping tank, and after passing through the de-pulping machine, it is pumped into the short fiber post-pulping tank. The degree of dissolution of the pulp after short fiber pulping is 15°SR.

[0049] (3) The waste paper is fed into the pulper for crushing, then pumped into the waste paper pulp tank, passed through the desoldering machine, and then pumped into the waste paper pulp tower;

[0050] (4) The ratio of the flow rate of the long fiber pulp, the short fiber pulp, and the waste pulp is set at 8:84:8. The pulp is pumped into the mixing tank, and after passing through the leveling mill, the power is set at 18kwh / t. Then it is pumped into the pulping tank. The pulp in the pulping tank has a beating degree of 30°SR. The added wet end chemicals include PAE type wet strength agent 3# with a solid content of 12.5% ​​and an addition amount of 25kg / t.

[0051] (5) The pulp is pumped to the headbox and then enters the tissue paper machine for forming, pressing and drying. The paper sheet dried to 85% dryness by the air hood and Yankee drying cylinder is creped by a ceramic doctor blade that is closely attached to the surface of the drying cylinder. The creping angle is set to 15°. Then it is wound and slit to obtain cream base paper.

[0052] (6) The crease rate of the fabricated base paper is 19%, the fine fiber content is 13%, and the total fiber crease rate is 2.8%.

[0053] The properties of the cream base paper and its corresponding cream paper produced by the methods described in Examples 1-3 of this invention were tested according to GB / T20808-2022, and the results are shown in the table below. The results show that the properties of the base paper and its corresponding cream paper from Examples 1-3 are similar to or better than the reference samples. By making targeted adjustments to the factors affecting the cream base paper during the production process (fiber raw material ratio, pulping process, type and amount of wet strength agent, adjustment of sizing conditions, and optimization of creping conditions), the requirements of end customers for cream paper were met, while the amount of long fibers used in the production process was reduced, thus improving the economic benefits of the enterprise.

[0054]

Claims

1. A production method for reducing the long fiber ratio of emulsion base paper, characterized in that, Includes the following steps: (1) Long fibers are fed into a long fiber hydraulic pulper for disintegration, then pumped into the long fiber pre-beating pulp tank, passed through a refiner, and then pumped into the long fiber post-beating pulp tank. The degree of disintegration of the pulp after long fiber beating is 25-35°SR, and the wet weight is 8.0-13.0g. (2) Short fibers are fed into a short fiber hydraulic pulper for pulping, then pumped into a pre-beating pulp tank, passed through a de-scraping machine, and then pumped into a post-beating pulp tank. The degree of freeness of the pulp after short fiber beating is 15-20°SR. (3) The waste paper is fed into the pulper for crushing, then pumped into the waste paper pulp tank, passed through the desoldering machine, and then pumped into the waste paper pulp tower; (4) Adjust the flow rates of long fiber after knocking, short fiber after knocking and waste pulp so that they are pumped into the mixing tank in proportion, and after passing through the leveling mill, they are then pumped into the pulping tank. (5) The pulp is pumped to the headbox and then enters the tissue paper machine for forming, pressing and drying; (6) The paper sheets dried to a semi-dry state by air hood and drying cylinder are wrinkled with a doctor blade at a dryness of 55-85% and a wrinkling rate of 18-25%. Then, they are wound and cut to obtain cream base paper. (7) Wherein, the physical properties (converted to single layer) of the cream base paper produced by the manufacturing method reach a basis weight of 10-20 g / m². 2 Longitudinal dry tensile index > 7.0 N·m / g, transverse dry tensile index > 3.0 N·m / g, longitudinal wet tensile index > 3.0 N·m / g, softness < 95 mN, bulk > 6.60 m 3 / g, lateral liquid absorption height >75mm / (100s).

2. The production method for reducing the long fiber ratio of emulsion base paper according to claim 1, characterized in that, The long fibers are one or more of cotton pulp, softwood pulp, and bamboo pulp; the pulping machine is two tandem disc mills.

3. The production method for reducing the long fiber ratio of emulsion base paper according to claim 1, characterized in that, The short fibers are hardwood pulp.

4. The production method for reducing the long fiber ratio of emulsion base paper according to claim 1, characterized in that, The ratio of long fiber knockout, short fiber knockout, and waste paper mass in the pulp mixing tank is (8-20):(85-70):(15-0), and the white water return flow rate is adjusted during pulping and mixing.

5. The production method for reducing the long fiber ratio of emulsion base paper according to claim 1, characterized in that, In step (4), the slurry dissolution degree of the slurry in the slurry forming tank is 25-45°SR.

6. The production method for reducing the long fiber ratio of emulsion base paper according to claim 1, characterized in that, The added wet-end chemicals include, but are not limited to, bactericides, softeners, and wet strength agents.

7. A production method for reducing the long fiber ratio of emulsion base paper according to claim 6, characterized in that, The wet strength agent is polyamide epichlorohydrin resin (i.e., PAE).

8. The production method for reducing the long fiber ratio of emulsion base paper according to claim 1, characterized in that, In step (6), the scraper is made of ceramic or carbon steel and the wrinkling angle is 15-35°.

9. A cream-based paper, characterized in that, It is produced by the production method according to any one of claims 1-8.

10. The cream-based paper according to claim 9, characterized in that, The physical properties (converted to single-layer) of the cream base paper reach a basis weight of 10-20 g / m². 2 Longitudinal dry tensile index > 7.0 N·m / g, transverse dry tensile index > 3.0 N·m / g, longitudinal wet tensile index > 3.0 N·m / g, softness < 95 mN, bulk > 6.60 m 3 / g, lateral liquid absorption height >75mm / (100s).

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