High-water-resistance packaging kraft base paper and papermaking method thereof

Abstract

The invention discloses high-water-resistance packaging kraft base paper and a papermaking method thereof. The method comprises the step that high-kappa-number hardwood pulp and recycled waste paper fibers which are prepared through a sulfate method are adopted for a surface layer and a bottom layer. After the slurry is ground, a water repellent agent is added, and a large-sizing-amount sizing metering rod is replaced, so that the treatment effect is improved. Through the method, the high-water-resistance packaging raw paper which is difficult to permeate when encountering water is produced. Under the condition that existing conditions are not changed greatly, the paper developed through the method has high water resistance, is suitable for manufacturing packaging boxes in packaging scenes of cold chain packaging, beverages and the like, meets the requirements of customers and improves the benefits of companies.

Description

Technical Field

[0001] The invention patent relates to the technical field of pulping and papermaking, and specifically to a highly water-resistant packaging kraft paper and a method for making the same. Background Art

[0002] With the development of society, people's material needs are increasing day by day, and the cartons for packaging fresh and frozen products need to be gradually enlarged. However, due to the hydrophilic characteristics of fibers, when conventional cartons come into contact with water, water enters between the fibers and combines with the fibers, causing the hydrogen bonds between the fibers to break and the strength of the cartons to be greatly reduced. Therefore, it is necessary to develop a high-water-resistant packaging kraft paper with a moderate price. Summary of the invention

[0003] The purpose of the present invention is to solve the above problems and develop a highly water-resistant packaging kraft paper that meets market demand based on existing conditions and with little change in cost.

[0004] The technical solution of the present invention to achieve the above purpose is to develop different raw material structure matching ratios, control the beating degree range of different pulps, adjust the different pulping ratios of the top and bottom layers of the paper machine, and optimize the water-repellent addition method, so as to achieve long-term and stable production of highly water-resistant packaging kraft paper.

[0005] The raw material matching ratio is that wood pulp is chemically pulped by the sulfate method to control the appropriate kappa number and beating degree. Waste paper raw materials are pulped by normal pulping methods to control the appropriate pulp beating degree. Both the top and bottom layers use broadleaf chemical pulp and waste paper raw materials.

[0006] The described control of the beating degree of different pulps, the broadleaf chemical pulp is beaten again by the disc refiner, and the pulp is further processed.

[0007] The pulping ratio of the surface and bottom layers of the paper machine is that both the surface and bottom layers are made of broadleaf chemical pulp and waste paper pulp in a matching ratio.

[0008] The optimized water repellent adding method is to add the water repellent during pulp mixing and paper machine surface sizing according to the action characteristics and molecular properties of the water repellent.

[0009] The water repellent is mainly alkyl ketene dimer, and the added amount per ton of paper accounts for 1.8-2.0% of the absolute dry pulp.

[0010] The present application also provides the use of the highly water-resistant packaging kraft paper described in the above technical solution or the highly water-resistant packaging kraft paper produced by the papermaking method described in the above technical solution as a packaging material. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] like Figure 1The papermaking method of a highly water-resistant packaging kraft paper shown in the figure is as follows: the two layers of pulp on the paper machine are mixed separately, most of the water-repellent agent is added when the pulp is mixed, and other chemical additives are added according to production conditions. The mixed pulp is sent to the paper machine for papermaking and forming. The water-repellent agent reacts with the fiber under the high temperature of the drying section to form a ketoester derivative and is positioned on the fiber. The hydrophobic end faces the surface of the fiber to form a hydrophobic layer, thereby reducing the combination of water and fiber. The water-repellent agent is then used at the sizing site to apply surface sizing to the opposite and bottom layers, and the outermost layer of fiber is further treated to ensure that the fiber reacts fully with the water-repellent agent. The post-drying section is dried again, sent to the calender for surface finishing, rolled into a large mother roll, and sent to the rewinder for slitting, packaging, and weighing according to different specifications required by customers. DETAILED DESCRIPTION

[0012] The raw material matching ratio is as follows: the top and bottom layers use broadleaf chemical pulp and waste paper fiber. The broadleaf is chemically pulped using the sulfate method, the Kappa number is controlled at 80-100, and the beating degree is controlled at 23-28°SR; the waste paper fiber is pulped using a normal pulping method, and the pulp beating degree is controlled at 30-40°SR.

[0013] The beating degree of different pulps is controlled. The broadleaf chemical pulp is beaten again by a disc refiner, and the beating degree is controlled at 30-35°SR; the beating degree of waste paper pulp is controlled at 30-40°SR.

[0014] The pulping ratio of the top and bottom layers of the paper machine is 40-50% of broadleaf chemical pulp and 50-60% of recycled waste paper pulp.

[0015] In the optimized water repellent adding method, most of the water repellent is added during pulp mixing, and the amount added per ton of paper in the surface layer accounts for 1.4-1.6% of the absolute dry pulp. A small part of the water repellent is added at the sizing point on the surface of the paper machine. By replacing the metering rod with a larger sizing amount, the water repellent is fully in contact with the fiber surface to ensure normal addition of the water repellent.

[0016] Among them, the water repellent is preferably alkyl ketene dimer, which is a cellulose reaction sizing agent. It can be used as both an in-slurry sizing agent and a surface sizing agent. It can easily react with the fiber at high temperature to generate a keto ester derivative and locate on the fiber. The hydrophobic end faces the surface of the fiber to form a hydrophobic layer, which has excellent waterproof properties.

[0017] After adding the water repellent, some other functional auxiliary agents are added to the mixed slurry. The specific addition can be added according to the actual production paper quality requirements. Specifically, the auxiliary agents include: dyes, retention aids, etc.

[0018] The papermaking method described above, after adding auxiliary materials such as water-repellent agent, the mixed slurry is papermade to produce highly water-resistant paper. Specifically, the process of papermaking with slurry includes: web forming, pressing and dehydrating, cylinder drying, surface sizing, calendering and other processes. The required quality paper is produced through the above papermaking process. The web forming process adopts long-wire paper sheet forming, the pressing and dehydrating process adopts shoe-shaped pressing, and the cylinder drying process adopts steam drying cylinder.

[0019] In the present invention, the basis weight of the base paper is preferably 100-110 g / m2.

[0020] The present invention includes a method for detecting the water resistance of the highly water-resistant packaging kraft paper.

[0021] Specifically, cut the base paper into A4 size, lay it flat on the table with the surface facing up, use a measuring cup to collect excess water, slowly pour it on the paper surface, take it off after 30 seconds and observe the back side; put it in an oven and dry it at 150°C for 5 minutes, take it out and repeat the same method, and observe it after 90 seconds. If there is no permeable spot on the back side, it proves that the water resistance is good.

[0022] The water absorption of this product is tested according to GB / T 1540-2002 "Determination of water absorption of paper and paperboard (Cobber method)". The water absorption value of the finished product made according to this specification is usually around 30 on the front side, while the water absorption value of paper made by conventional methods is around 80.

[0023] The characteristic of this technical solution is that it is based on the company's existing low-grade packaging paper production conditions, with slight adjustments, and with little increase in costs, it can significantly improve the water absorption resistance of the finished paper, meet customer needs, and improve the company's benefits.

[0024] The above technical solutions only reflect the preferred technical solutions of the present invention. Any changes that may be made to certain parts thereof by technicians in this technical field reflect the debugging and optimization of the present invention and fall within the protection scope of the present invention.

Claims

1. A highly water-resistant packaging kraft paper and a method for making the same, characterized in that By adjusting the ratio of each layer of pulp, controlling the beating degree of high card pulp, and optimizing the way of adding water-repellent agent, highly water-resistant packaging kraft paper is produced.

2. The method for making a highly water-resistant packaging kraft paper according to claim 1, characterized in that: The high calorie pulp is hardwood kraft chemical pulp; The step of refining the slurry comprises: The pulp beating degree is controlled at 30-35°SR.

3. The method for making a highly water-resistant packaging kraft paper according to claim 1, characterized in that: The paper machine is divided into two layers of pulp, the surface and bottom layers. Both the surface and bottom layers use 40-50% high card pulp and 50-60% recycled waste paper fiber. The main process flow is as follows: Mixed pulp tanks for each layer → feeding systems for each layer → forming in the wire section → dehydration in the press section → front drying → sizing → back drying → calendering → winding.

4. The method for making a highly water-resistant packaging kraft paper according to claim 1, characterized in that: The water repellent is alkyl ketene dimer, and the added amount of the water repellent is 1.8-2.0% of the absolute dry pulp.

5. The method for making highly water-resistant packaging kraft paper according to claim 1, characterized in that: Optimize the adding method of water repellent, and add the water repellent in the surface mixing pulp pool and the paper machine sizing area.

6. The optimized water repellent adding method according to claim 5, characterized in that: When adding water repellent, replace the sizing metering rod of the large sizing paper machine to increase the amount of water repellent and paper added per unit area.

7. A highly water-resistant packaging kraft paper, characterized in that: The highly water-resistant packaging kraft paper is made by the method for making highly water-resistant packaging kraft paper according to claims 1 to 6.

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