Ultrathin high-strength corrugating base paper and production process thereof

Abstract

The invention discloses ultrathin high-strength corrugating base paper and a production process thereof, and particularly relates to the technical field of corrugating base paper. The process comprises the following steps: mixing and hydraulically pulping different types of waste paper raw materials to obtain original waste paper pulp; original waste paper pulp enters a classifying screen after being subjected to high-concentration sand removal, coarse screening and low-concentration sand removal, and fibers in the waste paper pulp are screened into long fibers and short fibers; mixing the long fiber pulp and the short fiber pulp in proportion, and performing papermaking and surface sizing treatment; the ultra-thin high-strength corrugated base paper is obtained; papermaking comprises the step of adding poly dimethyl diallyl ammonium chloride into fiber pulp in a papermaking pool to carry out modification treatment; a mixed solution of a starch glue solution, a solid surface sizing agent, a styrene-acrylic surface sizing agent, 2, 3-epoxypropyltrimethylammonium chloride and alkenyl succinic anhydride is used as a surface sizing agent for surface sizing treatment. Through an in-pulp-surface double modification mode, the fiber strength and the waterproof performance of the ultrathin corrugating medium are remarkably improved under the condition that the enough thinness of the ultrathin corrugating medium is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of corrugated paper, and in particular to ultra-thin high-strength corrugated paper and a production process thereof. Background Art

[0002] Waste paper, also known as secondary fiber, is used as a raw material for papermaking. The paper industry's extensive recycling of waste paper not only reduces waste generation and potential environmental harm, but also generates economic benefits through the recycling of waste paper resources, protecting the ecological environment and conserving resources at the source.

[0003] Corrugated boxes are made of corrugated cardboard. Due to their multi-layer structure and good strength, they are widely used in packaging and transportation. During the loading process of goods, the corrugated paper needs to be folded multiple times to form a specific shape. However, due to the thickness of existing corrugated paper, the flexibility and foldability of the corrugated paper are poor during the folding process, which reduces its application in packaging performance.

[0004] With the rapid increase in demand for US waste in the domestic market, the US waste market is facing a supply shortage and rising prices, leading to a corresponding surge in paper prices. Furthermore, the government has further strengthened its control standards for imported waste, leading to a gradual decrease in direct imports. However, papermaking companies using domestic waste face a decline in quality due to the repeated recycling of raw materials. The high-strength corrugated paper produced from this raw material can only be considered medium-to-low-strength corrugated paper. For example, Chinese patent CN108215314A describes a low-cost corrugated cardboard production process, which includes the following steps: shredding waste paper, beating, mixing, applying the pulp to the screen, thermally gluing the paper, separating and creasing, slotting, printing, and joining. Through the synergistic effects of various raw materials and processing steps, the resulting corrugated cardboard box exhibits high structural strength and minimizes packaging space. Furthermore, due to the reduced wall thickness of each individual sheet of corrugated paper, the volume of the corrugated cardboard box itself is also reduced, saving storage and transportation costs. Although this patent uses waste paper, the corrugated base paper prepared mostly uses short fibers, which causes the strength of the corrugated paper to decrease during the thickness reduction process, and the thickness reduction is limited. In addition, this patent uses a glue coating machine for gluing. Although the glue is not specified in detail, conventional sizing agents are usually used. Conventional sizing agents have limited improvement on the strength of paper, and conventional sizing agents have limited ability to resist content and external extrusion.

[0005] Chinese patent CN109537349A discloses a process for producing low-weight, high-strength corrugated paperboard. The process uses a pulping mixture of 2-4 parts by weight of silica, 1-3 parts by weight of EPDM rubber, 2-5 parts by weight of vinyl acetate, and 10-15 parts by weight of polyethylene fiber. This effectively improves the strength of the corrugated paperboard while enhancing its durability and longevity, while ensuring that it does not deform and can withstand greater impact pressure. While this patent increases the impact pressure of the corrugated paper to a certain extent, it only improves its surface strength to a limited extent. Furthermore, the patent requires the addition of wheat straw and bamboo stalks with a high long-fiber content, which limits the utilization of waste cardboard. The resulting corrugated paper still fails to meet the requirements of being thin and high-strength. Summary of the Invention

[0006] To this end, the present invention provides an ultra-thin high-strength corrugated paper and a production process thereof to solve the problems in the prior art.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] According to one aspect of the present invention, a production process for ultra-thin high-strength corrugated paper is provided, the process comprising:

[0009] Step 1: Mix different types of waste paper raw materials and hydraulically pulp them to obtain raw waste paper pulp with a concentration of 2.5-2.8%;

[0010] Step 2: After high-concentration sand removal, coarse screening, and low-concentration sand removal, the original waste paper pulp enters a grading screen to separate the fibers in the waste paper pulp into long fibers and short fibers;

[0011] Step 3: mixing the long fiber pulp and the short fiber pulp in proportion, and performing papermaking and surface sizing treatment to obtain ultra-thin high-strength corrugated paper;

[0012] The papermaking process includes adding polydimethyldiallyl ammonium chloride to the fiber slurry in the papermaking pool for modification. In the modification process, the amount of polydimethyldiallyl ammonium chloride is 1 to 3 parts based on 100 parts of the dry weight of the fiber.

[0013] In the surface sizing process, a mixed reagent of starch glue, solid surface sizing agent, styrene acrylic surface sizing agent, 2,3-epoxypropyltrimethylammonium chloride and alkenyl succinic anhydride is used as a surface sizing agent for surface sizing treatment; in the surface sizing process, based on the amount of unsized paper being 1 ton, the amount of starch glue is 40-45 kg, the amount of solid sizing agent is 8-10 kg, the amount of styrene acrylic surface sizing agent is 2-3 kg, the amount of 2,3-epoxypropyltrimethylammonium chloride is 0.3-1 kg, and the amount of alkenyl succinic anhydride is 0.5-1.5 kg.

[0014] Furthermore, in step 1, the waste paper raw material includes 45-55wt% of a mixture of industrial carton waste paper, special grade waste paper, and mixed shopping mall waste paper, 25-30wt% of cardboard from pit card factories, 10-15wt% of industrial paper edge waste paper, and 5-15wt% of dry pulp bags.

[0015] Furthermore, in step 2, the long fibers are subjected to low-consistency sand removal, fine screening using a screen drum with a gap of 0.15-0.18 mm, and concentration treatment, and then refined and formed by controlling the SR beating degree to 39-41° to obtain long fiber pulp, which is then conveyed to the long fiber pulping pool; the short fibers are concentrated to obtain short fiber pulp, which is then conveyed to the short fiber pulping pool. Generally speaking, long fibers are those greater than 1.8 mm, and short fibers are those less than or equal to 1.8 mm. In the present invention, long fibers greater than 2.5 mm refer to long fibers greater than 2.5 mm accounting for more than 90%.

[0016] Furthermore, the long fiber pulp and the short fiber pulp in the papermaking tank are mixed in a ratio of (3-7): (7-3) to form paper pulp, and polydimethyldiallylammonium chloride is added for modification. The temperature of the papermaking tank is less than 45°C to reduce the risk of charge reversal.

[0017] Furthermore, in the step three, the paper is mechanically dehydrated after papermaking and dried before sizing to obtain unsized paper.

[0018] Furthermore, the pressure of the mechanical dehydration is 900-1100 KN / m.

[0019] Furthermore, the drying process before gluing includes drying at a temperature of 40-90° C. until the paper has a dryness of 90-92%, and the drying process after gluing includes drying at a temperature of 60-90° C. until the paper has a dryness of 85-92%. In the present invention, the drying temperature and paper dryness must be strictly controlled before and after gluing. Too high or too low a temperature will easily reduce the strength and other properties of the corrugated base paper.

[0020] Furthermore, the preparation process of the surface sizing agent is: firstly, 2,3-epoxypropyltrimethylammonium chloride and starch glue are mixed and modified, and then a solid sizing agent, a styrene acrylic surface sizing agent and alkenyl succinic anhydride are added and mixed evenly to obtain the surface sizing agent.

[0021] The starch glue is first modified with 2,3-epoxypropyltrimethylammonium chloride, so that 2,3-epoxypropyltrimethylammonium chloride is grafted onto starch to increase the charge density; the solid surface sizing agent and the styrene acrylic surface sizing agent can further enhance water resistance and improve surface strength, and alkenyl succinic anhydride (ASA) can be instantaneously cured to further enhance water resistance.

[0022] As an example, it is preferred to first mix 2,3-epoxypropyltrimethylammonium chloride with starch glue for modification and react at 60°C for 30 minutes, and then add alkenyl succinic anhydride, styrene acrylic emulsion and solid surface sizing agent in sequence.

[0023] Furthermore, the concentration of the starch glue is 8-12 wt% and the viscosity is 30-40 mPa.s.

[0024] According to another aspect of the present invention, an ultra-thin high-strength corrugated paper prepared by the above production process is provided, characterized in that the basis weight of the corrugated paper is 80-110 g / m 2 As an example, the preferred corrugated base paper weight is 80-90g / m 2 The thickness is preferably 0.12-0.18 mm.

[0025] The present invention has the following advantages:

[0026] The present invention uses different types of waste paper for mixing, covering the main types of packaging waste paper. Compared with the traditional process that only relies on a single waste paper (such as OCC) or requires additional foreign waste, the present invention makes full use of domestic recycled waste paper resources through a multi-waste paper ratio, reduces dependence on foreign waste (such as US waste), and complies with resource recycling policies. The present invention adds dry pulp bags, which are rich in long fibers (such as unbleached chemical pulp fibers), which can make up for the problem of short and broken fibers caused by multiple recycling of other waste papers (such as industrial carton waste paper and paper edge waste paper), improve the overall fiber length and strength of the raw materials, and provide a high-quality foundation for the subsequent preparation of long fiber pulp.

[0027] The present invention ensures a high-strength skeleton of the fluted paper by introducing a dry pulping bag and optimizing the ratio of various raw materials.

[0028] The present invention uses a double modification method of pulp inside and surface to significantly improve the fiber strength and waterproof performance of ultra-thin corrugated paper while ensuring that the paper is thin enough.

[0029] The present invention adds polydimethyldiallyl ammonium chloride to the fiber slurry to neutralize anionic impurities (such as hemicellulose), enhance the bonding force between fibers and improve the fiber dispersibility, and at the same time provide adsorption sites for the subsequent sizing agent (the surface is positively charged and is more likely to adsorb negatively charged alkenyl succinic anhydride); in the subsequent surface sizing agent, starch glue is used as a film-forming matrix, and a styrene acrylic surface sizing agent and starch glue are used to form a "fiber-starch-styrene acrylic surface sizing agent" membrane structure to enhance water resistance. The solid sizing agent and polydimethyldiallyl ammonium chloride form a charge relay to enhance the retention rate of fine fibers and strengthen the fiber network. Alkenyl succinic anhydride and the styrene acrylic surface sizing agent are cross-linked to form a dense film layer, thereby further enhancing the ring crush strength. The 2,3-epoxypropyltrimethylammonium chloride in the surface sizing further strengthens the cationic network, promotes the directional arrangement of alkenyl succinic anhydride and the styrene acrylic surface sizing agent on the fiber surface, and reacts with the cellulose hydroxyl group to form an ether bond to enhance water resistance.

[0030] In the process of preparing the surface sizing agent of the present invention, 2,3-epoxypropyltrimethylammonium chloride and starch glue are first mixed and modified, and then a solid sizing agent, a styrene acrylic surface sizing agent, and alkenyl succinic anhydride are added and mixed evenly. This can effectively prevent flocculation caused by charge reversal on the fiber surface, thereby avoiding a significant reduction in the effect of the surface sizing agent. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other implementation drawings based on the provided drawings without inventive effort.

[0032] The structures, proportions, sizes, etc. illustrated in this specification are intended only to complement the contents disclosed herein and to facilitate understanding and reading by persons familiar with the art. They are not intended to limit the conditions under which the present invention may be implemented and therefore have no substantive technical significance. Any structural modifications, changes in proportions, or adjustments in sizes, without affecting the efficacy and objectives of the present invention, shall still fall within the scope of the technical contents disclosed herein.

[0033] Figure 1 A flow chart of a pulping process in the production of ultra-thin high-strength corrugated paper provided in Example 1 of the present invention;

[0034] Figure 2 This is a flow chart of the papermaking process for producing ultra-thin high-strength corrugated paper provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0035] The following describes the implementation of the present invention using specific embodiments. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. Obviously, the embodiments described are only a portion of the present invention, not all of it. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0036] In this disclosure, premium wastepaper is divided into premium wastepaper cartons (X0) and premium mixed wastepaper (HH0). Premium wastepaper cartons (X0) are composite packaging cartons made entirely of virgin wood pulp, with each layer having essentially uniform color without noticeable color differences and containing no recycled pulp or other pulp components. Premium mixed wastepaper (HH0) primarily includes unbound, unlaminated, or unprinted white paper trimmings from printing factories, unprinted white office wastepaper, and pure white offset paper.

[0037] Corrugated cardboard: Corrugated cardboard generally refers to corrugated paper, while factory cardboard usually refers to scraps or waste generated during the carton factory production process. Corrugated cardboard is mainly composed of corrugated paper scraps and waste cartons. It is usually yellowish in color and contains a certain proportion of recycled fiber.

[0038] Mixed shopping mall waste paper: mainly waste paper generated in shopping malls, supermarkets and other places. It has a relatively complex composition and may include various wrapping papers, brochures, label papers, etc., and usually contains certain colored paper and coated paper.

[0039] Dry pulp bales are bales of waste pulp produced during the papermaking process, formed after drying. They are primarily composed of pulp fibers and are generally relatively pure, but may contain small amounts of additives or residues. Shenzhen Dacheng New Energy Technology Co., Ltd. imports these dry pulp bales from Vietnam. The long fibers in dry pulp bales are typically larger than 2.5 mm, while those in standard waste paper bins are typically only larger than 2.0 mm.

[0040] Industrial carton waste paper: mainly comes from packaging cartons in the industrial production process, usually kraft cartons, with high strength and good fiber quality, and is generally light yellow in color.

[0041] Industrial paper scraps: These are paper scraps generated during the industrial production process, such as cutting scraps produced by printing plants and carton factories. They are usually neat, have good fiber quality, and a relatively simple composition, mainly virgin fibers or less polluting recycled fibers.

[0042] Solid surface sizing agent (model: QN-388, Tai'an Qineng Chemical Technology Co., Ltd.);

[0043] Styrene acrylic surface sizing agent (model: MX-611, Mingxiang Chemical Technology (Shandong) Group Co., Ltd.);

[0044] Starch glue: permanent curing chemical, product number: CD606;

[0045] 2,3-Epoxypropyltrimethylammonium chloride: CAS 3033-77-0;

[0046] Alkenylsuccinic anhydride (ASA): CAS 25377-73-5.

[0047] Example 1

[0048] This embodiment provides a production process for ultra-thin high-strength corrugated paper. The waste paper raw materials are: waste paper (a mixture of industrial carton waste paper, special grade waste paper, and mixed shopping mall waste paper) accounting for 50wt%, cardboard from pit card factory accounting for 27wt%, industrial paper edge waste paper accounting for 13wt%, and dry pulping bales accounting for 10wt%. The pulping process is as follows: Figure 1 As shown, the paper making process is as follows Figure 2 The specific steps are as follows:

[0049] 1) Crushing and screening: The waste paper raw materials are fed into a hydraulic pulper through a chain conveyor for hydraulic shear crushing, then fed into a high-concentration desander for secondary high-concentration desanding to initially separate impurities, and then fed into a pulp tower for storage. The waste paper raw materials are then transported to a screening section for tertiary coarse screening to remove large impurities, and then fed into a tertiary low-concentration desanding section to further remove heavy impurities such as sand particles and metal chips from the pulp to obtain a fiber coarse pulp.

[0050] 2) Fiber classification: Use a grading screen to separate the fibers in the fiber pulp into long fiber pulp (long fiber length is more than 2.5mm) and short fiber pulp (short fiber length is less than 1.8mm) according to their length;

[0051] 3) Impurity removal and fiber fine screening: The long fibers are again subjected to four-stage low-concentration sand removal, followed by three-stage fine screening using a screen drum with a gap of 0.18 mm, and then concentrated by a multi-disc thickener (the concentration of the long fiber pulp after concentration is 4.5 wt%). The pulp is refined by controlling the beating degree of 40° SR to loosen the fibers, and then the long fiber pulp is obtained and transported to the long fiber pulping tank; the short fiber coarse pulp is concentrated by a multi-disc thickener (the concentration of the short fiber pulp after concentration is 4.5 wt%) to obtain the short fiber pulp and transported to the short fiber pulping tank;

[0052] 4) Slurry preparation and storage: Long fiber pulp and short fiber pulp were mixed in a weight ratio of 1:1 in a papermaking tank to form a uniform pulp with a concentration of 4.5 wt%, and polydimethyldiallyl ammonium chloride (2 parts per 100 parts of fiber dry weight) was added for modification.

[0053] 5) Forming and Dewatering: The pulp is evenly distributed at a concentration of 1% and fed to the papermaking machine to the wire section for papermaking. The fibers are interwoven on the wire section to form a wet paper web. The paper web is then mechanically dewatered at a pressure of 1000 kN / m in the press section and dried at 65°C to a dryness of 91% to obtain unsized paper.

[0054] 6) Surface sizing and drying: 0.6 kg of 2,3-epoxypropyltrimethylammonium chloride and 43 kg of starch glue (with a concentration of 10 wt% and a viscosity of 35 MPa.s) were mixed and modified, and then 8 kg of a solid sizing agent, 3 kg of a styrene acrylic surface sizing agent, and 1 kg of alkenyl succinic anhydride were added and mixed to prepare a surface sizing agent; then, 1 ton of unsized paper was sized using the surface sizing agent, and then the paper was dried at 75° C. until the paper dryness reached 89%;

[0055] 7) Winding and slitting: The paper web is rewound and slit by the winder and then cut according to the customer's specifications.

[0056] 8) Packaging and warehousing: Finished products are packaged and stored.

[0057] Example 2

[0058] This embodiment provides a production process for ultra-thin high-strength corrugated paper. The waste paper raw materials are: 55 wt% of waste paper (a mixture of industrial carton waste paper, special grade waste paper, and mixed shopping mall waste paper), 27 wt% of cardboard from a cardboard factory, 13 wt% of industrial paper waste, and 5 wt% of dry pulp bales. The specific steps are as follows:

[0059] 1) Crushing and screening: The waste paper raw materials are fed into a hydraulic pulper through a chain conveyor for hydraulic shear crushing, then fed into a high-concentration desander for secondary high-concentration desanding to initially separate impurities, and then fed into a pulp tower for storage. The waste paper raw materials are then transported to a screening section for tertiary coarse screening to remove large impurities, and then fed into a tertiary low-concentration desanding section to further remove heavy impurities such as sand particles and metal chips from the pulp to obtain a fiber coarse pulp.

[0060] 2) Fiber classification: Use a grading screen to separate the fibers in the fiber pulp into long fiber pulp (long fiber length is more than 2.5mm) and short fiber pulp (short fiber length is less than 1.8mm) according to their length;

[0061] 3) Impurity removal and fiber fine screening: The long fibers are again subjected to four-stage low-concentration sand removal, followed by three-stage fine screening using a screen drum with a gap of 0.18 mm, and then concentrated by a multi-disc thickener (the concentration of the long fiber pulp after concentration is 4.5 wt%). The pulp is refined at a controlled 41° SR beating degree to loosen the fibers, and then the long fiber pulp is obtained and transported to the long fiber pulping tank; the short fiber coarse pulp is concentrated by a multi-disc thickener (the concentration of the short fiber pulp after concentration is 4.5 wt%) to obtain the short fiber pulp and transported to the short fiber pulping tank;

[0062] 4) Slurry preparation and storage: Long fiber pulp and short fiber pulp are mixed in a weight ratio of 1:1 in a papermaking tank to form a uniform pulp with a concentration of 4 wt%, and polydimethyldiallyl ammonium chloride (1 part of polydimethyldiallyl ammonium chloride is used for 100 parts of fiber dry weight) is added for modification;

[0063] 5) Forming and Dewatering: The pulp is evenly distributed at a concentration of 0.5% and fed to the papermaking machine to the wire section for papermaking. The fibers are interwoven on the wire section to form a wet paper web. The paper web is then mechanically dewatered at a pressure of 900 kN / m in the press section and dried at 40°C to a dryness of 90% to obtain unsized paper.

[0064] 6) Surface sizing and drying: 0.6 kg of 2,3-epoxypropyltrimethylammonium chloride and 40 kg of starch glue (with a concentration of 12 wt% and a viscosity of 40 MPa.s) were mixed and modified, and then 10 kg of a solid sizing agent, 3 kg of a styrene acrylic surface sizing agent, and 0.5 kg of alkenyl succinic anhydride were added and mixed to prepare a surface sizing agent; then, the surface sizing agent was used to sizing 1 ton of unsized paper, and then the paper was dried at 90° C. until the paper dryness reached 92%;

[0065] 7) Winding and slitting: The paper web is rewound and slit by the winder and then cut according to the customer's specifications.

[0066] 8) Packaging and warehousing: Finished products are packaged and stored.

[0067] Example 3

[0068] This embodiment provides a production process for ultra-thin high-strength corrugated paper. The waste paper raw materials are: waste paper (a mixture of industrial carton waste paper, special grade waste paper, and mixed shopping mall waste paper) accounting for 45wt%, cardboard from a cardboard factory accounting for 27wt%, industrial paper waste accounting for 13wt%, and dry pulp bales accounting for 15wt%. The specific steps are as follows:

[0069] 1) Crushing and screening: The waste paper raw materials are fed into a hydraulic pulper through a chain conveyor for hydraulic shear crushing, then fed into a high-concentration desander for secondary high-concentration desanding to initially separate impurities, and then fed into a pulp tower for storage. The waste paper raw materials are then transported to a screening section for tertiary coarse screening to remove large impurities, and then fed into a tertiary low-concentration desanding section to further remove heavy impurities such as sand particles and metal chips from the pulp to obtain a fiber coarse pulp.

[0070] 2) Fiber classification: Use a grading screen to separate the fibers in the fiber pulp into long fiber pulp (long fiber length is more than 2.5mm) and short fiber pulp (short fiber length is less than 1.8mm) according to their length;

[0071] 3) Impurity removal and fiber fine screening: The long fibers are again subjected to four-stage low-concentration sand removal, followed by three-stage fine screening using a screen drum with a gap of 0.18 mm, and then concentrated by a multi-disc thickener (the concentration of the long fiber pulp after concentration is 4.5 wt%). The pulp is refined at a 39° SR beating degree to loosen the fibers, and then the long fiber pulp is obtained and transported to the long fiber pulping tank; the short fiber coarse pulp is concentrated by a multi-disc thickener (the concentration of the short fiber pulp after concentration is 4.5 wt%) to obtain the short fiber pulp and transported to the short fiber pulping tank;

[0072] 4) Slurry preparation and storage: Long fiber pulp and short fiber pulp are mixed in a weight ratio of 1:1 in a papermaking tank to form a uniform pulp with a concentration of 5 wt%, and polydimethyldiallyl ammonium chloride (3 parts per 100 parts of fiber dry weight) is added for modification;

[0073] 5) Forming and Dewatering: The pulp is evenly distributed at a concentration of 1.5% and fed to the papermaking machine to the wire section for papermaking. The fibers are interwoven on the wire section to form a wet paper web. The paper web is then mechanically dewatered at a pressure of 1100 kN / m in the press section and dried at 90°C to a dryness of 92% to obtain unsized paper.

[0074] 6) Surface sizing and drying: First, 1 kg of 2,3-epoxypropyltrimethylammonium chloride and 45 kg of starch glue (with a concentration of 8 wt% and a viscosity of 30 MPa.s) were mixed and modified, and then 8 kg of a solid sizing agent, 2 kg of a styrene acrylic surface sizing agent, and 1.5 kg of alkenyl succinic anhydride were added and mixed to prepare a surface sizing agent; then, the surface sizing agent was used to sizing 1 ton of unsized paper, and then the paper was dried at 60° C. until the paper dryness reached 85%;

[0075] 7) Winding and slitting: The paper web is rewound and slit by the winder and then cut according to the customer's specifications.

[0076] 8) Packaging and warehousing: Finished products are packaged and stored.

[0077] Example 4

[0078] This embodiment provides a production process for ultra-thin high-strength corrugated paper. The difference between this embodiment and embodiment 1 is that in step 4), the long fibers and short fibers are mixed in a weight ratio of 3:7, and other conditions are the same as those in embodiment 1.

[0079] Example 5

[0080] This embodiment provides a production process for ultra-thin high-strength corrugated paper. The difference between this embodiment and embodiment 1 is that in step 4), the long fibers and short fibers are mixed in a weight ratio of 4:6, and other conditions are the same as those in embodiment 1.

[0081] Example 6

[0082] This embodiment provides a production process for ultra-thin high-strength corrugated paper. The difference between this embodiment and embodiment 1 is that in step 4), the long fibers and short fibers are mixed in a weight ratio of 6:4, and other conditions are the same as those in embodiment 1.

[0083] Example 7

[0084] This embodiment provides a production process for ultra-thin high-strength corrugated paper. The difference between this embodiment and embodiment 1 is that in step 4), the long fibers and short fibers are mixed in a weight ratio of 7:3, and other conditions are the same as those in embodiment 1.

[0085] Comparative Example 1

[0086] This comparative example provides a production process for ultra-thin high-strength corrugated paper, which differs from Example 1 in that polydimethyldiallylammonium chloride is not added in step 4), and other conditions are the same as those in Example 1.

[0087] Comparative Example 2

[0088] This comparative example provides a production process for ultra-thin high-strength corrugated paper, which differs from Example 1 in that 2,3-epoxypropyltrimethylammonium chloride is not added in step 6), and other conditions are the same as those in Example 1.

[0089] Comparative Example 3

[0090] This comparative example provides a production process for ultra-thin high-strength corrugated paper, which differs from Example 1 in that no styrene acrylic surface sizing agent is added in step 6), and other conditions are the same as those in Example 1.

[0091] Comparative Example 4

[0092] This comparative example provides a production process for ultra-thin high-strength corrugated paper, which differs from Example 1 in that alkenyl succinic anhydride is not added in step 6), and other conditions are the same as those in Example 1.

[0093] Comparative Example 5

[0094] This comparative example provides a production process for ultra-thin high-strength corrugated paper, which differs from Example 1 in that, in step 4), based on 100 parts of fiber dry weight, the amount of polydimethyldiallyl ammonium chloride is 5 parts; in step 6), based on 1 ton of unsized paper, the amount of starch glue is 44.1 kg, the amount of solid sizing agent is 8 kg, the amount of styrene acrylic surface sizing agent is 1 kg, the amount of 2,3-epoxypropyltrimethylammonium chloride is 0.5 kg, and the amount of alkenyl succinic anhydride is 2 kg. Other conditions are the same as in Example 1.

[0095] Comparative Example 6

[0096] This embodiment provides a production process for ultra-thin high-strength corrugated paper, which differs from Example 1 in that the waste paper raw materials are: waste paper (a mixture of industrial carton waste paper, special-grade waste paper, and mixed shopping mall waste paper) accounting for 60wt%, cardboard from pit card factories accounting for 27wt%, industrial paper edge waste paper accounting for 13wt%, and dry pulp bales accounting for 0wt%, long fibers are above 2.0mm (2.0-2.3mm accounts for more than 90%), and short fibers are below 1.8mm; other conditions are the same as in Example 1.

[0097] Comparative Example 7

[0098] This embodiment provides a production process for ultra-thin high-strength corrugated paper, which differs from Example 1 in that the surface sizing agent in step 6) is prepared by blending 43 kg of starch glue (with a concentration of 10 wt% and a viscosity of 35 MPa.s), 0.6 kg of 2,3-epoxypropyltrimethylammonium chloride, 8 kg of solid sizing agent, 3 kg of styrene acrylic surface sizing agent, and 1 kg of alkenyl succinic anhydride. Other conditions are the same as in Example 1.

[0099] Comparative Example 8

[0100] This embodiment provides a production process for ultra-thin high-strength corrugated paper. The difference between this embodiment and embodiment 1 is that the drying conditions in step 5) are: 95°C, 94% dryness; the drying conditions in step 6) are: 55°C, 80% dryness; other conditions are the same as in embodiment 1.

[0101] Test Example 1

[0102] The ultra-thin (corrugated paper basis weight 80-110g / m2) prepared in the above embodiment and comparative example were respectively 2 Performance tests were conducted on high-strength corrugated base paper (0.12-0.18 mm thick). Basis weight: GB / T 451.2, tightness = basis weight / thickness, thickness: ISO 534, ring crush strength: GB / T 2679.8, breaking length: GB / T 13023, and water absorption: GB / T 1540. The test results are shown in Tables 1 and 2 below.

[0103] Table 1

[0104] <![CDATA[Quantitative (g / m 2 )]]> Thickness (mm) Example 1 82 0.125 Example 2 100 0.172 Example 3 95 0.155 Example 4 105 0.165 Example 5 90 0.155 Example 6 95 0.142 Example 7 105 0.173 Comparative Example 1 128 0.198 Comparative Example 2 85 0.155 Comparative Example 3 88 0.161 Comparative Example 4 90 0.152 Comparative Example 5 95 0.135 Comparative Example 6 125 0.211 Comparative Example 7 92 0.144 Comparative Example 8 91 0.151 Commercially available 140 0.561

[0105] Table 2

[0106]

[0107]

[0108] As shown in Tables 1 and 2, while the performance of Examples 2 and 3 is within the specified range, the best synergy between long and short fibers is achieved at a 10% dry pulp bale ratio. When the dry pulp bale ratio is reduced or increased, insufficient or excessive long fibers will result in increased basis weight and thickness, and a slight decrease in ring pressure. By individually controlling the long and short fiber ratio (Examples 4-7), it was found that the closer the ratio is to 1:1, the better the performance indicators are, with the best effect being achieved at a 1:1 long and short fiber ratio.

[0109] Without the addition of a wet-end enhancer (Comparative Example 1), the fiber bonding force is reduced, the network structure is loose, and the tightness decreases. Without a surface epoxy modifier (Comparative Example 2), the film voids increase and the water absorption increases. Without ASA (Comparative Example 4), the water resistance collapses and the water absorption is the highest. Direct blending of the sizing agent (Comparative Example 7) causes charge reversal, sizing flocculation, and reduced tempering length. Without the addition of a dry pulp bag (Comparative Example 6), relying solely on the long fibers in the waste paper, the long fibers are insufficient in length, the long and short fibers are out of balance, the basis weight increases, and the tightness decreases. Without the addition of a styrene acrylic surface sizing agent (Comparative Example 3), the "fiber-starch-styrene acrylic" composite film is destroyed, the ring pressure index decreases, the water absorption increases, and the breaking length decreases. The amount of polydimethyldiallylammonium chloride and the amount of sizing agent used in Comparative Example 5 are far greater than those in Example 1. However, excessive positive charge will reverse the potential on the fiber surface, electrostatic repulsion between fibers, destroy the uniformity of the paper sheet, and reduce the ring pressure index; excessive ASA will cause the precipitate to block the capillaries, increase local water absorption, and cause local collapse of the ring pressure; excessive or reduced amounts of any additives will destroy the precise coordination of "charge relay-crosslinking film formation", resulting in a complete collapse of performance.

[0110] Although the present invention has been described in detail above using general descriptions and specific embodiments, it will be apparent to those skilled in the art that modifications and improvements may be made thereto. Therefore, such modifications and improvements, without departing from the spirit of the present invention, are intended to be within the scope of protection claimed herein.

Claims

1. A production process for ultra-thin high-strength corrugated paper, characterized in that: The process comprises: Step 1: Mix different types of waste paper raw materials and hydraulically pulp them to obtain raw waste paper pulp with a concentration of 2.5-2.8%; Step 2: After high-concentration sand removal, coarse screening, and low-concentration sand removal, the original waste paper pulp enters a grading screen to separate the fibers in the waste paper pulp into long fibers and short fibers; Step 3: mixing the long fiber pulp and the short fiber pulp in proportion, and performing papermaking and surface sizing treatment to obtain ultra-thin high-strength corrugated paper; The papermaking process includes adding polydimethyldiallyl ammonium chloride to the fiber slurry in the papermaking pool for modification. In the modification process, the amount of polydimethyldiallyl ammonium chloride is 1 to 3 parts based on 100 parts of the dry weight of the fiber. In the surface sizing process, a mixed reagent of starch glue, solid surface sizing agent, styrene acrylic surface sizing agent, 2,3-epoxypropyltrimethylammonium chloride and alkenyl succinic anhydride is used as a surface sizing agent for surface sizing treatment; in the surface sizing process, based on the amount of unsized paper being 1 ton, the amount of starch glue is 40-45 kg, the amount of solid sizing agent is 8-10 kg, the amount of styrene acrylic surface sizing agent is 2-3 kg, the amount of 2,3-epoxypropyltrimethylammonium chloride is 0.3-1 kg, and the amount of alkenyl succinic anhydride is 0.5-1.5 kg.

2. The production process of ultra-thin high-strength corrugated paper according to claim 1, characterized in that: In step 1, the waste paper raw materials include 45-55wt% of a mixture of industrial carton waste paper, special grade waste paper, and mixed shopping mall waste paper, 25-30wt% of cardboard from pit card factory, 10-15wt% of industrial paper edge waste paper, and 5-15wt% of dry pulp bag.

3. The production process of ultra-thin high-strength corrugated paper according to claim 1, characterized in that: In the step 2, the long fibers are subjected to low-concentration sand removal again, fine screening and concentration treatment using a screen drum with a gap of 0.15-0.18 mm, and pulping and forming with a controlled SR beating degree of 39-41° to obtain long fiber pulp, which is then transported to a long fiber pulping pool; the short fibers are subjected to concentration treatment to obtain short fiber pulp, which is then transported to a short fiber pulping pool.

4. The production process of ultra-thin high-strength corrugated paper according to claim 1, characterized in that: The long fiber pulp and the short fiber pulp in the papermaking tank are mixed in a ratio of (3-7): (7-3) to form paper pulp, and polydimethyldiallylammonium chloride is added for modification.

5. The production process of ultra-thin high-strength corrugated paper according to claim 1, characterized in that: In the step 3, the paper is mechanically dehydrated after papermaking and dried before sizing to obtain unsized paper.

6. The production process of ultra-thin high-strength corrugated paper according to claim 5, characterized in that: The pressure of the mechanical dehydration is 900-1100 KN / m.

7. The process for producing ultra-thin high-strength corrugated paper according to claim 5, characterized in that: The drying treatment before gluing includes treating the paper at a temperature of 40-90° C. until the paper dryness reaches 90-92%, and the drying treatment after gluing includes treating the paper at a temperature of 60-90° C. until the paper dryness reaches 85-92%.

8. The process for producing ultra-thin high-strength corrugated paper according to claim 1, characterized in that: The preparation process of the surface sizing agent is as follows: firstly, 2,3-epoxypropyltrimethylammonium chloride and starch glue are mixed and modified, and then a solid sizing agent, a styrene acrylic surface sizing agent and alkenyl succinic anhydride are added and mixed evenly to obtain the surface sizing agent.

9. The process for producing ultra-thin high-strength corrugated paper according to claim 8, characterized in that: The concentration of the starch glue is 8-12 wt% and the viscosity is 30-40 mPa.s.

10. An ultra-thin high-strength corrugated paper prepared by the production process according to any one of claims 1 to 9, characterized in that: The basis weight of the corrugated paper is 80-110 g / m 2 .

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