A method for preparing high-permeability and high-strength paper bag paper

Abstract

The present invention relates to the technical field of paper bag paper processing, and specifically to a method for preparing paper bag paper with high air permeability and high strength. The method comprises the following steps: pretreating wood pulp to obtain pretreated pulp, mixing the pretreated pulp with water, obtaining pulp by low-concentration beating, mixing the pulp with polylactic acid fiber and cationized wood nanocellulose, making paper, and drying. The present invention increases the mechanical strength on the basis of greatly improving the air permeability by mixing the pulp with polylactic acid fiber and adding cationized wood nanocellulose into the pulp. The tensile index is increased by 33.4% compared with that without addition, the tear index is increased by 44.07%, the burst index is increased by 16.9%, and the air permeability is increased by 988%. Both the strength and air permeability meet the use requirements of national excellent paper bag paper. The present invention provides a new idea for the production of paper bag paper, and has a certain market value and good application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of paper bag paper processing, and in particular to a method for preparing high-air permeability and high-strength paper bag paper. Background Art

[0002] Paper bag paper is an important packaging material in my country. In the industrial production process, it is usually necessary to transport, pack, and stack. In this process, the paper bag paper is prone to imbalance of internal and external air pressure due to poor air permeability. It is also susceptible to strong impact force, which eventually leads to bag breakage and loss of raw materials. Therefore, the preparation of a high-permeability and high-strength paper bag paper plays an extremely important role in the packaging production in the field of paper bag paper.

[0003] The strength properties of paper bag paper can usually be improved by adding papermaking enhancers, and the commonly used papermaking additives in the industry are mostly starches such as cationic and anionic starches. They are not easily soluble at room temperature and usually require heating, and will flocculate and agglomerate if stored for a long time. Chinese patent CN105131137A discloses a method for preparing cationic starch, which needs to be cooked at 100°C during use. The required conditions are high and the effect of improving strength properties is limited. At the same time, adding excessive cationic starch will block the pores of the paper and reduce the rate of gas in and out, ultimately resulting in a significant decrease in air permeability. Therefore, finding a new method to prepare paper bag paper with fully improved air permeability and strength properties has broad application prospects. Summary of the invention

[0004] In view of the above problems, the present invention provides a method for preparing high-permeability and high-strength paper bag paper, which is achieved by the following technical solutions:

[0005] A method for preparing high-permeability and high-strength paper bag paper comprises the following steps:

[0006] A method for preparing high-permeability and high-strength paper bag paper comprises the following steps:

[0007] (1) pretreating wood pulp to obtain pretreated pulp;

[0008] (2) mixing the pretreated pulp with water and beating the pulp to obtain a slurry;

[0009] The pulp, polylactic acid fiber and cationic wood nanocellulose are mixed and then paper is made; and pressure drying is performed to obtain high-permeability and high-strength sack paper.

[0010] Particularly, in the step (1), the pretreatment is:

[0011] Soak the wood pulp in water and disperse it into blocks; loosen, sieve, filter, squeeze out the water and balance the water content;

[0012] The block has a length of 20 mm to 25 mm and a width of 20 mm to 25 mm;

[0013] The speed of the decomposition is 800 rpm to 1200 rpm;

[0014] The equilibrium moisture is obtained by placing the mixture at -4°C to 4°C for 24 to 48 hours.

[0015] Particularly, the wood pulp in step (1) is unbleached coniferous wood pulp.

[0016] Particularly, in the step (2), the polylactic acid fibers account for 10% to 20% of the absolute dry pulp of the paper bag paper; and the cationized wood nanocellulose accounts for 5% to 10% of the absolute dry pulp of the paper bag paper.

[0017] Particularly, in the step (2), the pulp concentration after beating is 3% to 6%, and the beating degree is 15 to 20°SR.

[0018] Particularly, in the step (2), the pressure of the pressurized drying is 0.8-1.0 MPa, the time is 8-10 min, and the drying temperature is 80-90°C.

[0019] In particular, after press drying, the paper weight is 80-120 g / m 2 .

[0020] A high-air-permeability and high-strength paper bag paper is prepared by any of the above-mentioned preparation methods.

[0021] The invention mixes pulp with polylactic acid fiber and adds cationic wood nanocellulose into the pulp. On the basis of greatly improving the air permeability, the strength performance is greatly improved. Compared with the case without adding cationic wood nanocellulose, the tensile index is increased by 33.4%, the tear index is increased by 44.07%, the burst index is increased by 16.9%, and the air permeability is increased by 988%. The strength and air permeability meet the national requirements for the use of excellent paper bag paper. It provides a new idea for the production of paper bag paper and has certain market value and good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a SEM (scanning electron microscope) image of the paper produced in Example 1 of the present invention.

[0023] Figure 2 This is a SEM picture of another area of ​​the paper made in Example 1 of the present invention. DETAILED DESCRIPTION

[0024] In order to better understand the present invention, the present invention is further described below in conjunction with specific examples, wherein the terms used in the examples are for describing specific embodiments and do not constitute limitations on the scope of protection of the present invention.

[0025] In the present invention:

[0026] Polylactic acid fiber comes from: Shenzhen Guanghua Weiye Co., Ltd.

[0027] Cationized wood nanocellulose from: Guangxi University.

[0028] Example 1

[0029] (1) Take 30g of unbleached coniferous wood pulp and soak it in 0.5L of water at room temperature for 6h. Tear the soaked pulp into small pieces of 25mm*25mm. Place the pulp in a pulp deflaker for deflaking at a speed of 1000rpm. Turn on the motor and start the agitator to disintegrate the interwoven fibers or fiber bundles into single fibers. Sieve to filter the water and squeeze out the water. Place in a -4℃ freezer for 36h to balance the moisture.

[0030] (2) Add water to the prepared pulp to 300g, equivalent to a pulp concentration of 10%, and beat it in a PFI beater, low-concentration beating (pulp concentration 5%) to 20°SR, mix the 85% absolute dry pulp with 10% polylactic acid fiber, and decompose it. Add 5% cationic wood nanocellulose through an automatic Kaiser papermaking system, stir the pulp, filter the water through a sieve, and automatically form it. The paper sheet has a radius of 10cm and is vacuum dried at 90°C and 0.8MPa pressure for 8min to obtain base paper with a paper weight of 80g / m 2 .

[0031] Example 2

[0032] (1) Take 30g of unbleached coniferous wood pulp and soak it in 0.5L of water at room temperature for 6h. Tear the soaked pulp into small pieces of 25mm*25mm. Place the pulp in a pulp deflaker for deflaking at a speed of 1000rpm. Turn on the motor and start the agitator to disintegrate the interwoven fibers or fiber bundles into single fibers. Sieve to filter the water and squeeze out the water. Place in a -4℃ freezer for 36h to balance the moisture.

[0033] (2) Add water to the prepared pulp to 300g, equivalent to a pulp concentration of 10%, and beat it in a PFI beater, low-concentration pulping (pulp concentration 5%) to 20°SR, mix the 78% absolute dry pulp with 15% polylactic acid fiber, and decompose it. Add water and 7% cationic wood nanocellulose through an automatic Kaiser papermaking system, stir the pulp, filter the water through a sieve, and automatically form it. The paper sheet has a radius of 10cm and is vacuum dried at 90°C and 0.8MPa pressure for 8min to obtain base paper with a paper weight of 80g / m 2 .

[0034] Example 3

[0035] (1) Take 30g of unbleached coniferous wood pulp and soak it in 0.5L of water at room temperature for 6h. Tear the soaked pulp into small pieces of 25mm*25mm. Place the pulp in a pulp deflaker for deflaking at a speed of 1000rpm. Turn on the motor and start the agitator to disintegrate the interwoven fibers or fiber bundles into single fibers. Sieve to filter the water and squeeze out the water. Place in a -4℃ freezer for 36h to balance the moisture.

[0036] (2) Add water to the prepared pulp to 300g, equivalent to a pulp concentration of 10%, and beat it in a PFI beater, low-concentration pulping (pulp concentration 5%) to 20°SR, mix the 70% absolute dry pulp with 20% polylactic acid fiber, and decompose it. Add 10% cationic wood nanocellulose through an automatic Kaiser papermaking system, stir the pulp, filter the water through a sieve, and automatically form it. The paper sheet has a radius of 10cm and is vacuum dried at 90°C and 0.8MPa pressure for 8min to obtain base paper with a paper weight of 80g / m 2 .

[0037] Comparative Example 1

[0038] This comparative example refers to the preparation method of Example 1, except that: polylactic acid fiber and cationic wood nanocellulose are not added.

[0039] Comparative Example 2

[0040] This comparative example refers to the preparation method of Example 1, except that only 15% of polylactic acid fiber is added.

[0041] Comparative Example 3

[0042] This comparative example refers to the preparation method of Example 1, except that only 7% of cationized wood nanocellulose is added.

[0043] The test results of Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Table 1:

[0044] The test method is the test method recorded in "GB / T 7968-2015 Paper Bag Paper" and "GB / T 454-2020 Determination of Paper Burst Resistance".

[0045] Table 1 Performance test results

[0046]

[0047] The test results show that adding only one additive can only significantly improve one performance, and cannot significantly improve both the air permeability and strength performance, making it difficult to meet the daily use requirements of paper bag paper. After adding polylactic acid fiber and cationic wood nanocellulose at the same time, as the amount of both added increases, the strength and air permeability of the paper are greatly improved. The tensile index is increased by 33.4% compared to no addition, the tear index is increased by 44.07%, the burst index is increased by 16.9%, and the air permeability is increased by 988%. The strength and air permeability have reached the national requirements for the use of excellent paper bag paper.

[0048] The above detailed description is a specific description of one feasible embodiment of the present invention. The embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification that does not deviate from the present invention should be included in the scope of the technical solution of the present invention.

Claims

1. A method for preparing high air permeability and high strength sack paper, characterized in that: The following steps are involved: (1) 30 g of unbleached coniferous wood pulp was soaked in 0.5 L of water at room temperature for 6 h, and the soaked pulp was torn into small pieces of 25 mm*25 mm. The pulp was placed in a pulp deflaker for deflaking at a speed of 1000 rpm. The motor was turned on to start the agitator to dissociate the interwoven fibers or fiber bundles into single fibers. The fibers were filtered through a sieve, the water was squeezed out, and the fibers were placed in a -4°C freezer for 36 h to balance the moisture. (2) Add water to the prepared pulp to 300 g, equivalent to a pulp concentration of 10%, and beat it in a PFI beater. Use a pulp concentration of 5% to beat to 20°SR. Mix the 70% absolute dry pulp with 20% polylactic acid fiber, and decompose it. Add water to a mass concentration of cationized wood nanocellulose of 10% through an automatic Kaiser papermaking system. Stir the pulp, filter the water through a sieve, and automatically form it. Vacuum dry it at 90°C and 0.8 MPa for 8 minutes to obtain base paper with a paper weight of 80 g / m 2 , the paper page radius is 10cm.

2. A high air permeability, high strength paper bag paper, characterized in that Prepared by the preparation method described in claim 1.

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