A special paper for corner protectors and its preparation process

Abstract

This invention relates to a special paper for corner protectors and its preparation process, wherein the special paper for corner protectors has a basis weight of 420 g / m², a basis weight difference of ≤3.0% across widths, and a density of 0.65 ± 0.02 g / cm². 3 Longitudinal ring crush index ≥ 8 N·m / g, interlaminar bond strength ≥ 80 J / m², and burst strength ≥ 1.0 kPa·m 2 / g, the moisture content of the finished paper is 6.8±0.2%, and the COBB value of the finished paper is 200-400g / ㎡; the preparation process includes: (1) preparing sprayed starch, in-slurry starch and filler; (2) pulping; (3) mixing and papermaking; (4) rewinding and packaging. This invention can realize the production of special paper for paper corner protectors by adjusting the pulping, paper machine and other processes, effectively reducing the production cost, reducing the number of paper layers and reducing the amount of glue used in the production of paper corner protectors, and shortening the drying time of the glue in the production of paper corner protectors.

Description

Technical Field

[0001] This invention relates to the field of papermaking technology, and in particular to a special paper for corner protectors and its preparation process. Background Technology

[0002] In recent years, the domestic paper industry has seen a steady development, and paper corner protectors have gained increasing attention and are widely used in the packaging industry. During the transportation of goods on wooden pallets, paper corner protectors can protect the edges and corners of the goods, turning loose and fragmented cardboard boxes, boards, metal pipes, electronic components, and other items into a sturdy whole, preventing the goods from tilting or collapsing. They also act as a buffer when subjected to external impacts. When unpacking, it is only necessary to cut the packing or wrapping film.

[0003] Density refers to the weight per unit volume of paper, also known as density. From a manufacturing perspective, paper density is affected by many factors, including the type of pulp, the degree of beating, the amount of filler, and pressing and calendering. In the current process of preparing paper corner protectors, multiple layers of paper are often bonded together. This results in a high density and excessive rigidity of the paper corner protector, making it unsuitable for packaging soft products, products requiring high adhesion, or other products that need cushioning. At the same time, the method of bonding multiple layers of paper together increases costs, affects product price, and is not conducive to use.

[0004] Therefore, in order to provide cushioning for products to be packaged and reduce production costs, this invention provides a low-density, low-cost paper corner protector and its preparation process, which is beneficial to the production and preparation of paper corner protectors and to improving their application. Summary of the Invention

[0005] To address the problems in the background art, the present invention provides a special paper for paper corner protectors and its preparation process.

[0006] This invention provides a special paper for paper corner protectors and its preparation process, which adopts the following technical solution:

[0007] A preparation process for a special paper for paper corner protectors includes the following preparation steps:

[0008] 1. Preparation of sprayed starch, starch in slurry, and fillers;

[0009] 2. Pulping;

[0010] 3. Mixing and forming paper;

[0011] 4. Rewinding and packaging;

[0012] Step 2 includes:

[0013] Preparation of the first pulp: Domestic waste COCC11#D and domestic waste pagoda tube are put into the pulper in proportion for pulping. The pulp enters the discharge tank from the pulper, and then passes through a high-consistency desander and a coarse screen for purification. It then passes through a fine screen for further purification. After that, the fibers are concentrated by passing through a multi-disc concentrator. The pulp after multi-disc concentrator is directly sent to the post-pulping tank for use without beating.

[0014] Preparation of the second pulp: Pulp raw materials are poured into the silo and fed into the bottom conveyor belt through the silo discharge port, and then into the pulp tank through the conveyor belt; water is added to the pulp tank according to the pulp raw material concentration of 5%; after mixing, the mixture is stirred for 10 minutes and pumped into the pulp raw material storage well; the pulp is pumped from the pulp storage well into the unloading pool, mixed with domestic waste pulp, and then entered into the subsequent process section; the pulp raw materials are poplar wood pulp raw materials directly purchased from the market.

[0015] By adopting the above technical solution, more long fibers can be retained in the pulp, which is conducive to the production of thicker paper corner protectors, which in turn helps to reduce the number of paper layers in the paper corner protectors, and thus helps to reduce the production cost of paper corner protectors. The pulp raw material is mainly unprocessed poplar pulp, which is cheaper than domestic waste paper. After disintegration, the degree of beating is 16-20°SR, and the wet weight is between 3.2-3.5g. The various physical properties are also more in line with the performance of paper corner protectors.

[0016] Furthermore, in step 2, the pulp concentration is 3-3.5%; the coarse screen feed pulp concentration is 2.5-3.0%, the feed pressure is 0.15-0.3 MPa, and the pressure difference is 0.05-0.09 MPa; the fine screen feed pulp concentration is 1.8-2.0%, the feed pressure is 0.1-0.25 MPa, and the pressure difference is 0.02-0.04 MPa; the multi-disc feed pulp concentration is 1.5-2.0%, the outlet concentration is 5.0-5.5%, and the white water concentration is ≤0.03%, so that long fibers are retained.

[0017] By adopting the above technical solutions, the outflow of long fibers can be avoided, which is beneficial to the production of special paper corner protectors and can ensure the thickness of the paper layers. By reducing the concentration of pulp entering the fine screen and controlling it at 1.8-2.0%, the pass rate of long fibers in the fine screen is increased, thereby increasing the fiber length and reducing the paper density. At the same time, no beating is performed during the pulping process, reducing fiber cutting and fracturing, increasing the fiber length and reducing the paper density. It also improves the dewatering efficiency of the wire section and reduces the moisture content of the exit roll, which is beneficial to the production of special paper corner protectors.

[0018] Furthermore, step 3 includes:

[0019] Pulp production line: Wastewater and pulp raw materials are mixed and pumped into a mixing tank. Papermaking sludge and talc are added to the mixing tank. The papermaking sludge is water treatment biochemical sludge with a concentration of 2-3%, added at a rate of 5 kg per ton of paper. The talc concentration is 30%, added at a rate of 60-80 kg per ton of paper. After thorough mixing in the mixing tank, the mixed pulp is pumped to the pre-paper tank at a rate of 2.0-4.0 kg per ton of paper. It is then sequentially transferred to a high-level tank, a flushing pump, and a pressure screen. Aluminum sulfate and polyaluminum chloride are added in the high-level tank for sizing. After purification by the pressure screen, the pulp is transported to the headbox. The pulp is made by controlling the online concentration at 1.0-1.5%, and then the paper is formed, pressed, dehydrated and dried. During the online forming stage, starch is sprayed between the paper layers to promote paper bonding. The concentration of the sprayed starch is 20%, and the amount added per ton of paper is 1.5-2.5 kg. When pressing, because the tightness requirement of the special paper for corner protectors is relatively low, the press section is pre-pressed in two stages. The pressure of the first and second stages is controlled at 40, 60, 90 and 100 kg / cm², respectively. After drying, the calender is closed without pressure, and the paper is then wound to obtain the special paper for corner protectors.

[0020] By adopting the above technical solution, due to the high dewatering efficiency of the wire section, the high dewatering efficiency of the exit roll, and the low moisture content of the exit roll, the pressing pressure in the pressing section can be appropriately reduced. The first positive pressure is reduced from 100 kg / cm² to 80 kg / cm², and the second positive pressure is reduced from 110 kg / cm² to 90 kg / cm². The calender is opened without applying pressure, further reducing the density. This is beneficial to improving the production efficiency of special paper corner protectors and reducing production costs.

[0021] Further, the aluminum sulfate concentration is 10%, and the addition amount per ton of paper is 3.0-5.0 kg; the polyaluminum chloride concentration is 10%, and the addition amount per ton of paper is 3.0-5.0 kg; starch in the pulp is added before the pulp pump, the starch concentration in the pulp is 20%, and the addition amount per ton of paper is 1.5-2.0 kg; a retention aid and filter aid are added before the pressure screen purification (at the pressure screen inlet), the concentration of which is 0.3%, and the dosage per ton of paper is 0.3-0.4 kg.

[0022] By adopting the above technical solution, the rosin contained in domestic waste materials can be utilized, eliminating the need to add additional rosin or AKD. Using a mixed solution of aluminum sulfate and polyalumina helps to reduce the production cost of special paper corner protectors. At the same time, the rosin continues to mature after leaving the machine, reducing the paper's water absorption value and causing instability in the water absorption value. Eliminating the need for additional rosin effectively mitigates this situation and also reduces the amount of adhesive in the system.

[0023] Furthermore, the longitudinal ring crush index is ≥8 N·m / g, and the interlayer bond strength is ≥80 J / m. 2The burst strength is ≥1.0 kPa·m² / g, the moisture content of the paper is 7±0.5%, and the COBB value of the paper is 200-400 g / m³. 2 .

[0024] Further, step 1 of the preparation process is as follows:

[0025] Preparation of sprayed starch: Add water to the dissolving tank and start stirring. Slowly add corn starch to the dissolving tank. The weight ratio of water to corn starch is 4:1. Stir evenly and ensure stirring time is more than 20 minutes. The preparation temperature is 30-35℃. Filter to obtain a 20% concentration of sprayed starch for later use.

[0026] Preparation of starch in slurry: Add water to the dissolving tank and start stirring. Slowly add corn starch to the dissolving tank. The weight ratio of water to corn starch is 4:1. Stir evenly and ensure stirring time is more than 20 minutes. Prepare at 30-35℃, filter, and obtain starch in slurry with a concentration of 20% for later use.

[0027] Preparation of filler: Add water to the dissolving tank and start stirring. Slowly add talc powder to the dissolving tank. The weight ratio of water to talc powder is 7:3. Stir evenly and ensure stirring time is more than 20 minutes. Filter to obtain talc powder with a concentration of 30% for later use.

[0028] Step 4 of the preparation process is as follows:

[0029] The basis weight is controlled within ≤3.0%, the moisture content is controlled within 7±0.5%, the paper is rewound and the end face is neat, the paper surface is flat, and finally it is packaged to obtain the finished product.

[0030] By adopting the above technical solution, the Honeywell QCS system scanning frame is used to monitor the paper's basis weight and moisture fluctuations in real time. The bottom wire dilution water system is automatically adjusted according to the fluctuation points, which can solve the problem of uneven basis weight thickness in the longitudinal and transverse directions that may be caused by reduced pressure in the press section or no pressure in the calender. The Honeywell QCS system used in this technical solution is existing technology and is not the innovation of this technology.

[0031] Furthermore, the specifications of the special paper for making paper corner protectors include 360g / ㎡, 420g / ㎡ and 500g / ㎡.

[0032] By adopting the above-mentioned technical solution, namely the preparation method provided in this application, it is possible to prepare special paper for paper corner protectors of various specifications, which is beneficial to improving the practicality of this technology.

[0033] Furthermore, when the specification of the special paper for the paper corner protectors is 420g / ㎡, the rewinding speed in step 4 is controlled at 1200-1400m / min.

[0034] By adopting the above technical solution, it is beneficial to realize the production of paper corner protectors with a specification of 420g / ㎡.

[0035] Furthermore, when the specification of the special paper for the paper corner protectors is 500g / ㎡, the rewinding speed in step 4 is controlled at 1000-1100m / min.

[0036] By adopting the above technical solution, it is possible to produce paper corner protectors with a specification of 500g / ㎡.

[0037] A special paper for corner protectors, with a basis weight of 420 g / m², a basis weight difference of ≤3.0% across the width, and a density of 0.65 ± 0.02 g / cm². 3 .

[0038] In summary, the present invention has the following beneficial technical effects:

[0039] 1. The innovation of this invention lies in the addition of pulp raw materials in the preparation process of special paper for paper corner protectors. The raw materials are prepared by mixing the pulp raw materials with domestic waste pulp. At the same time, the pressure on the coarse sieve after mixing is reduced, so that more long fibers are retained, which ensures the thickness of the final product. This allows the thickness of special paper for paper corner protectors to be achieved with fewer layers, thereby reducing production costs.

[0040] 2. The preparation process provided by this invention does not involve pulping, which reduces the loss of fiber length and thus helps to increase the thickness of the paper layer.

[0041] 3. The paper corner protector produced by the preparation process provided by the present invention has a lower density and higher porosity, which is beneficial to the dehydration and drying efficiency of the paper corner protector during the production process, and helps to improve the production efficiency of the paper corner protector; at the same time, it is beneficial to protect the product surface, achieve the effect of cushioning and shock absorption, and thus help to improve the stability of the packaging and improve the practicality of the paper corner protector.

[0042] 4. The preparation process provided by this invention controls the pulp concentration on the wire, avoiding problems such as excessively rapid and intense dewatering of the wire section due to high pulp concentration, which leads to excessive fiber loss and poor paper formation. Adding retention and filtration aids to the pulp can effectively reduce fiber loss and improve the retention rate of pharmaceuticals and fine fibers, thereby improving paper performance.

[0043] 5. The preparation process provided by this invention uses aluminum sulfate and polymerized alumina, eliminating the need for additional rosin glue, which helps reduce costs and also reduces adhesives in the system. Detailed Implementation

[0044] The technical solutions in the embodiments of the present invention have been clearly and completely described. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] Example 1

[0046] 1) Prepare starch for use in slurry:

[0047] Add 6000 kg of water to the dissolving tank and start stirring. Slowly add 2000 kg of modified corn starch to the dissolving tank, and add another 2000 kg of water. The weight ratio of water to corn starch is 4:1. Stir evenly and ensure stirring time is 25 minutes. Filter to obtain 20% starch slurry for later use.

[0048] 2) Prepare sprayed starch for later use:

[0049] Add 6000 kg of water to the dissolving tank and start stirring. Slowly add 2000 kg of modified corn starch to the dissolving tank, and add another 2000 kg of water. The weight ratio of water to corn starch is 4:1. Stir evenly and ensure stirring time is 25 minutes. Filter to obtain a 20% concentration sprayed starch for later use.

[0050] 3) Prepare talc powder for later use:

[0051] Add 5000 kg of water to the dissolving tank and start stirring. Slowly add 3000 kg of talc powder to the dissolving tank, and then add 2000 kg of water. The weight ratio of water to talc powder is 7:3. Stir evenly and ensure stirring time is 20 minutes. Filter to obtain talc powder with a concentration of 30% for later use.

[0052] 4) Pulping:

[0053] Pulping line: Waste COCC11#D and pagoda-shaped pipe are fed into the pulper at a ratio of COCC11#D:pagoda-shaped pipe = 1:4, resulting in a pulp concentration of 3.5%, and then enter the discharge tank. After passing through a high-consistency separator and a coarse screen for purification, the pulp concentration at the coarse screen is 3.0%, the inlet pressure is 0.28 MPa, and the pressure difference is 0.06 MPa. Then, it passes through a fine screen with an inlet concentration of 1.9%, an inlet pressure of 0.15 MPa, and a pressure difference of 0.02 MPa for further purification. The fibers are then concentrated using a multi-disc system, with an inlet concentration of 1.8%, an outlet concentration of 5.5%, and a white water concentration of 0.01%. The pulp after multi-disc concentration enters the finishing tank for later use.

[0054] Slurry Raw Material Production Line: A forklift is used to pour 5 scoops of slurry raw material into a hopper. The material falls through the hopper's lower outlet onto a conveyor belt, which then transports the slurry to a 50 m³ preparation tank. Water is added to the tank to achieve a slurry concentration of 5%, and the mixture is stirred for 10 minutes. The mixture is then pumped into a 70 m³ usage tank. Finally, the slurry is discharged into the unloading tank according to a 13% usage rate.

[0055] 5) Mixing and papermaking:

[0056] Pulp Line: The mixed pulp of domestic waste and pulp raw materials is pumped into the mixing tank. Papermaking sludge, talc, and bentonite are added to the mixing tank. The papermaking sludge is water treatment biochemical sludge with a concentration of 3% and an addition rate of 5 kg per ton of paper. The talc concentration is 20% and an addition rate of 60 kg per ton of paper. After thorough mixing in the mixing tank, the mixed pulp is pumped to the pre-paper tank, then sequentially transferred to the high-level tank, the flushing pump, and the pressure screen. Aluminum sulfate and polyaluminum chloride are added to the high-level tank. The aluminum sulfate concentration is 10%, and the addition rate is 60 kg per ton of paper. The pulp contains 5.0 kg of polyaluminum chloride (PAC) at a concentration of 10%, with a ton-of-paper addition of 6 kg. Before the pulp pump, 20% starch is added to the pulp at a concentration of 20%, with a ton-of-paper addition of 12 kg. Before pressure screen purification (at the pressure screen inlet), a retention and filtration aid is added at a concentration of 0.035%, with a ton-of-paper addition of 0.5 kg. After further pressure screen purification, the purified pulp is transported to the headbox for papermaking, while the online concentration is controlled at 1.3%. Finally, the pulp is formed on the wire, pressed, dewatered, and dried. During the online forming stage, starch is sprayed between the paper layers to promote bonding; the sprayed starch concentration is 20%, with a ton-of-paper addition of 10 kg. Then, it is laminated with the surface layer. During pressing, pre-pressing is performed first and second, with positive pressing pressures of 40, 50, 80, and 90 kg / cm² respectively. After drying, the calender is closed without pressure, and finally, the pulp is wound to obtain the corner protector paper.

[0057] 6) Rewinding and packaging:

[0058] The rewinding speed is controlled at 1300m / min, the basis weight is controlled at a width difference of ≤3.0%, the moisture content is controlled at 7.0%, the rewinding end face is neat, the paper surface is flat, and finally the finished product is packaged.

[0059] The main indicators of the paper corner protectors prepared by the above method were tested, and the results are shown in Table 1 below:

[0060] Table 1

[0061]

[0062] The main technical indicators of the products obtained above show that the basis weight difference of the horizontal direction is well controlled, the paper density is low, and the ring crush index, bursting strength index and interlayer bonding strength are all far higher than the standard. The water absorption is controlled above the minimum value, and the moisture content is controlled to the upper limit, which meets the requirements.

[0063] Example 2

[0064] 1) Prepare starch for use in slurry:

[0065] Add 6000 kg of water to the dissolving tank and start stirring. Slowly add 2000 kg of modified corn starch to the dissolving tank, and add another 2000 kg of water. The weight ratio of water to corn starch is 4:1. Stir evenly and ensure stirring time is 25 minutes. Filter to obtain 20% starch slurry for later use.

[0066] 2) Prepare sprayed starch for later use:

[0067] Add 6000 kg of water to the dissolving tank and start stirring. Slowly add 2000 kg of modified corn starch to the dissolving tank, and add another 2000 kg of water. The weight ratio of water to corn starch is 4:1. Stir evenly and ensure stirring time is 25 minutes. Filter to obtain a 20% concentration sprayed starch for later use.

[0068] 3) Prepare talc powder for later use:

[0069] Add 5000 kg of water to the dissolving tank and start stirring. Slowly add 3000 kg of talc powder to the dissolving tank, and then add 2000 kg of water. The weight ratio of water to talc powder is 7:3. Stir evenly and ensure stirring time is 20 minutes. Filter to obtain talc powder with a concentration of 30% for later use.

[0070] 4) Pulping:

[0071] Pulping line: Waste COCC11#D and pagoda-shaped pipe are fed into the pulper at a ratio of COCC11#D:pagoda-shaped pipe = 1:4, resulting in a pulp concentration of 3.5%, and then enter the discharge tank. After passing through a high-consistency separator and a coarse screen for purification, the pulp concentration at the coarse screen is 3.0%, the inlet pressure is 0.28 MPa, and the pressure difference is 0.06 MPa. Then, it passes through a fine screen with an inlet concentration of 1.9%, an inlet pressure of 0.15 MPa, and a pressure difference of 0.02 MPa for further purification. The fibers are then concentrated using a multi-disc system, with an inlet concentration of 1.8%, an outlet concentration of 5.5%, and a white water concentration of 0.01%. The pulp after multi-disc concentration enters the finishing tank for later use.

[0072] Slurry Raw Material Production Line: A forklift is used to pour 5 scoops of slurry raw material into a hopper. The material falls through the hopper's lower outlet onto a conveyor belt, which then transports the slurry to a 50 m³ preparation tank. Water is added to the tank to achieve a slurry concentration of 5%, and the mixture is stirred for 10 minutes. The mixture is then pumped into a 70 m³ usage tank. Finally, the slurry is discharged into the unloading tank according to a 13% usage rate.

[0073] 5) Mixing and papermaking:

[0074] Pulp Line: The mixed pulp of domestic waste and pulp raw materials is pumped into the mixing tank. Papermaking sludge, talc, and bentonite are added to the mixing tank. The papermaking sludge is water treatment biochemical sludge with a concentration of 3% and an addition rate of 5 kg per ton of paper. The talc concentration is 20% and an addition rate of 60 kg per ton of paper. After thorough mixing in the mixing tank, the mixed pulp is pumped to the pre-paper tank, then sequentially transferred to the high-level tank, the flushing pump, and the pressure screen. Aluminum sulfate and polyaluminum chloride are added to the high-level tank. The aluminum sulfate concentration is 10%, and the addition rate is 60 kg per ton of paper. The pulp contains 5.0 kg of polyaluminum chloride (PAC) at a concentration of 10%, with a ton-of-paper addition of 6 kg. Before the pulp pump, 20% starch is added to the pulp at a concentration of 20%, with a ton-of-paper addition of 12 kg. Before pressure screen purification (at the pressure screen inlet), a retention and filtration aid is added at a concentration of 0.035%, with a ton-of-paper addition of 0.5 kg. After further pressure screen purification, the purified pulp is transported to the headbox for papermaking, while the online concentration is controlled at 1.3%. Finally, the pulp is formed on the wire, pressed, dewatered, and dried. During the online forming stage, starch is sprayed between the paper layers to promote bonding; the sprayed starch concentration is 20%, with a ton-of-paper addition of 10 kg. Then, it is laminated with the surface layer. During pressing, pre-pressing is performed first and second, with positive pressing pressures of 40, 50, 80, and 90 kg / cm² respectively. After drying, the calender is closed without pressure, and finally, the pulp is wound to obtain the corner protector paper.

[0075] 6) Rewinding and packaging:

[0076] The rewinding speed is controlled at 1100m / min, the basis weight is controlled at a width difference of ≤3.0%, the moisture content is controlled at 7.0%, the rewinding end face is neat, the paper surface is flat, and finally the finished product is packaged.

[0077] The main indicators of the paper corner protectors prepared by the above method were tested, and the results are shown in Table 2 below:

[0078] Table 2

[0079]

[0080] The main technical indicators of the products obtained above show that the basis weight difference of the horizontal direction is well controlled, the paper density is low, and the ring crush index, bursting strength index and interlayer bonding strength are all far higher than the standard. The water absorption is controlled above the minimum value, and the moisture content is controlled to the upper limit. At the same time, due to the increase in thickness, the water absorption value increases, but it still meets the requirements.

[0081] Specialized paper for corner protectors is made from carefully selected domestic waste materials, which undergo screening, slag removal, purification, and concentration processes, but without refining. Since corner protectors differ from yarn tube paper in their application and do not require excessively high interlayer bonding strength, refining is unnecessary. This reduces wear on refining sheets, lowers electricity consumption, and thus saves costs. Furthermore, not refining also reduces fiber length loss, which contributes to increased thickness. During papermaking, appropriate addition of in-pulp starch and sprayed starch meets customer requirements for paper strength. The addition of aluminum sulfate and polyaluminum chloride results in a base paper with a good COBB value, thus exhibiting good sizing properties. During base paper production, stable machine speed, controlled basis weight and moisture content, and adjusted press pressure ensure good paper density and uniformity. Controlling the pulp concentration before wire bonding prevents excessive fiber re-flocculation due to high pulp concentration, which can lead to rapid and intense dewatering, significant fiber loss, and poor paper sheet formation. Adding retention and filtration aids to the pulp effectively reduces fiber loss and improves the retention rate of pharmaceuticals and fine fibers, thereby enhancing paper performance.

[0082] The purpose of this invention is to improve the production cost of paper corner protectors and meet current market demands. Taking the 6mm thick paper corner protectors used in the market as an example, it takes about 11 sheets to produce them using ordinary 420g / ㎡ paperboard (density of about 0.75), while only 9 sheets are needed to achieve the required thickness using 420g / ㎡ special paper corner protector paper (density of about 0.65). By reducing the number of paper layers, the amount of glue used in the paper corner protector production process is also reduced, the drying time of the glue is reduced, and the production cost of paper corner protectors is lowered.

[0083] It should be noted that, in this document, terms such as "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0084] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A process for the preparation of a paper corner-protector paper, characterized in that, The preparation steps include: Step 1. Preparation of spraying starch, pulp starch and filler; Step 2. Pulping; Step 3. Mixing, paper making; Step 4. Rewinding, packaging; Step 2 includes: Preparation of the first pulp: the waste COCC11#D and the waste pagoda tube are put into the pulper according to the proportion, and the pulp is discharged from the pulper into the discharge tank, then passes through the high-concentration de- sludge device, the coarse screen for screening and purification, then passes through the fine screen for further screening and purification, and then the fiber passes through the multi-disc for concentration, and the pulp after the multi-disc concentration is directly discharged into the beating tank for standby use without beating; Preparation of the second pulp: the pulp raw material is poured into the hopper, enters the bottom conveyor belt through the hopper discharge port, and enters the pulp tank through the conveyor belt; water is added to the pulp tank according to the pulp raw material concentration of 5%; after mixing, stirring for 10 minutes, pumping into the pulp raw material storage well; from the pulp raw material storage well, the discharge tank is mixed with the waste pulp, and then enters the subsequent section, wherein the pulp raw material is a poplar pulp raw material directly purchased from the market; The pulping concentration in step 2 is 3-3.5%; the coarse screen inlet pulp concentration is 2.5-3.0%, the inlet pulp pressure is 0.15-0.3 MPa, and the pressure difference is 0.05-0.09 MPa; the fine screen inlet pulp concentration is 1.8-2.0%, the inlet pulp pressure is 0.1-0.25 MPa, and the pressure difference is 0.02-0.04 MPa; the multi-disc inlet pulp concentration is 1.5-2.0%, the outlet concentration is 5.0-5.5%, and the white water concentration is ≤0.03%, so that the long fibers are retained; Step 3 includes: Pulp line: the mixed pulp of waste and pulp raw material enters the mixing tank through the pulp pump, papermaking sludge and talcum powder are added in the mixing tank, the papermaking sludge is water treatment biochemical sludge, the sludge concentration is 2-3%, the ton paper addition amount is 5 kg; the talcum powder concentration is 30%, the ton paper addition amount is 60-80 kg; after fully mixing and stirring in the mixing tank, the mixed pulp is pumped to the pre-beating tank through the pulp pump, the ton paper amount is 2.0-4.0 kg; then it is sequentially transferred to the headbox, the flush pump and the pressure screen, wherein aluminum sulfate and polyaluminum chloride are added in the headbox for sizing; the pulp after purification by the pressure screen is delivered to the headbox for paper pulp making, while the wire concentration is controlled to be 1.0-1.5%; finally, the paper is formed, pressed, dewatered and dried; during the forming stage, spraying starch is sprayed between the layers of paper to promote the combination of the paper, the spraying starch concentration is 20%, and the ton paper addition amount is 1.5-2.5 kg; during the pressing, the paper corner special paper requires low tightness, so the pre-pressing and the positive pressure of the pressing part are controlled to be 40, 60, 90 and 100 kg / c㎡ respectively, the calender is closed without pressure after drying, and then the paper corner special paper is prepared after winding.

2. A process for the preparation of a paper corner protector paper as claimed in claim 1, wherein: The aluminum sulfate concentration is 10%, the ton paper addition amount is 3.0-5.0 kg; the polyaluminum chloride concentration is 10%, the ton paper addition amount is 3.0-5.0 kg; the in-pulp starch is added before the slurry pump, the in-pulp starch concentration is 20%, the ton paper addition amount is 1.5-2.0 kg; the retention and drainage aid is added before the pressure screen purification, that is, at the pressure screen inlet, the concentration is 0.3%, the ton paper amount is 0.3-0.4 kg.

3. A process for the preparation of a paper corner protector paper as claimed in claim 1, wherein: The longitudinal ring pressure index is ≥8 N·m / g, the interlayer bonding strength is ≥80 J / m², the burst strength is ≥1.0 kPa·㎡ / g, the paper moisture is 7±0.5%, and the paper COBB value is 200-400 g / ㎡.

4. A process for the preparation of a paper corner protector paper according to any one of claims 1 to 3, characterized in that: Step 1 of the preparation process is: Preparation of spray starch: water is added to the dissolving tank, and stirring is started, corn starch is slowly added to the dissolving tank, the weight ratio of water to corn starch is 4:1, stirring is uniform, the stirring time is ensured to be more than 20 minutes, the preparation temperature is 30-35℃, filtration is performed, and 20% spray starch is prepared for standby; Preparation of in-pulp starch: water is added to the dissolving tank, and stirring is started, corn starch is slowly added to the dissolving tank, the weight ratio of water to corn starch is 4:1, stirring is uniform, the stirring time is ensured to be more than 20 minutes, the preparation temperature is 30-35℃, filtration is performed, and 20% in-pulp starch is prepared for standby; Preparation of filler: water is added to the dissolving tank, and stirring is started, talc is slowly added to the dissolving tank, the weight ratio of water to talc is 7:3, stirring is uniform, the stirring time is ensured to be more than 20 minutes, filtration is performed, and 30% talc is prepared for standby; Step 4 of the preparation process is: the quantitative control is ≤3.0%, the moisture control is 7±0.5%, rewinding is performed, the end face is neat, the paper surface is flat, and finally the finished product is packaged.

5. A process for the preparation of a paper corner protector paper as claimed in claim 4, wherein: The specifications of the paper corner special paper prepared include 360 g / ㎡, 420 g / ㎡ and 500 g / ㎡.

6. A process for the preparation of a paper corner protector paper as claimed in claim 5, wherein: When the specification of the paper corner special paper is 420 g / ㎡, the rewinding speed control in step 4 is 1200-1400 m / min.

7. A process for the preparation of a paper corner protector paper as claimed in claim 5, wherein: When the specification of the paper corner special paper is 500 g / ㎡, the rewinding speed control in step 4 is 1000-1100 m / min.

8. A paper corner protector paper, characterized by: The paper corner special paper prepared according to the preparation process of claim 5 has a basis weight of 420 g / ㎡, a cross direction basis weight difference of ≤3.0%, and a tightness of 0.65±0.02 g / cm³.

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