Process for preparing paperboard core layer by grinding chemi-mechanical pulp

Abstract

A paperboard core layer preparation process for performing accurate grinding treatment on chemi-mechanical pulp comprises a step of preparing the chemi-mechanical pulp through a chemi-mechanical pulp production line, and further comprises the following steps: pulp supply: the chemi-mechanical pulp production line provides the chemi-mechanical pulp to a double-disc mill; pulping: performing accurate grinding processing on the chemithermomechanical pulp by using the double-disc mill to obtain accurately ground chemithermomechanical pulp; material mixing: conveying the finely ground chemi-mechanical pulp to a core-layer pulp mixing tank, and mixing with chemi-mechanical pulp, waste pulp and chemical pulp in the core-layer pulp mixing tank to form mixed pulp; and paper making: conveying the mixed pulp to a PM32 paper machine for paper making. Accurately-ground chemi-mechanical pulp is added into the core layer through stable pulp preparation and is uniformly mixed with non-accurately-ground chemi-mechanical pulp and broken paper pulp, and the fiber length and the separating degree are balanced, so that the fiber interweaving capacity of the core layer is improved, the fibers are interwoven more tightly, the binding force between the fibers is enhanced, and the fiber bonding strength and the folding strength are improved. Compared with the prior art, the production cost can be greatly reduced on the premise of ensuring the performance of the paperboard.

Description

Technical Field

[0001] This invention relates to the field of papermaking technology, and specifically to a process for preparing a cardboard core layer by grinding chemimechanical pulp. Background Technology

[0002] White cardboard core layers need to have high bulk, uniformity, and stiffness to support the coating and printing performance of the surface layer. Food-grade cardboard (such as paper cup base paper, lunch box base paper, etc.) needs to meet the requirements of lightweight, high stiffness, high whiteness, and safety. In addition to having high bulk, uniformity, and stiffness, it also needs to have high bonding strength and folding endurance.

[0003] Traditional production processes for white cardboard and food-grade cardboard involve adding 50%-70% chemimechanical pulp to the core layer, controlling the freeness at 350-420 csf, and the bulk at 2.2-2.5 cm. 3 / g, while adding a certain proportion of long and short fiber chemical pulps (bleached softwood pulp, bleached hardwood pulp) to the core layer to improve the bonding strength of the paper, so as to meet the physical and printing properties of the paper.

[0004] However, adding long and short fiber chemical pulp to the core layer is costly and results in insufficient bulk. Traditional chemimechanical pulping techniques suffer from problems such as insufficient strength and poor whiteness stability. Researching fine refining technology for the core layer of white cardboard and food-grade cardboard is of great significance. It can balance fiber length and the degree of fiber separation, thereby improving the fiber interlacing ability of the core layer, increasing fiber bonding strength and folding endurance, while significantly reducing production costs.

[0005] Therefore, there is an urgent need for a technology to solve the above-mentioned technical problems. Summary of the Invention

[0006] The purpose of this invention is to provide a process for preparing the core layer of cardboard by grinding chemical mechanical pulp, in order to solve the above-mentioned technical problems. The technical solution adopted by this invention is as follows: 1. A process for preparing a cardboard core layer by fine grinding of chemimechanical pulp, comprising the step of preparing chemimechanical pulp through a chemimechanical pulp production line, characterized in that it further comprises the following steps: The chemimechanical pulp production line supplies chemimechanical pulp to the dual-disc mill, and the feed pulp concentration is set to 4.5-5.5%. The chemimechanical pulp is finely ground using a dual-disc mill with a pulp freeness set to 180-220 csf and the dual-disc mill is equipped with 46-inch grinding discs to obtain a finely ground chemimechanical pulp. Mixing involves conveying the refined chemimechanical pulp to the core mixing tank, where it is mixed with the chemimechanical pulp, waste pulp, and chemical pulp to form a mixed pulp. The ratio of the refined chemimechanical pulp, chemimechanical pulp, and waste pulp is 5-15%: 50-70%: 10-25%, with the remainder being chemical pulp. Papermaking involves feeding the mixed pulp to the PM32 paper machine for papermaking.

[0007] 2. The process for preparing a cardboard core layer by fine grinding of chemimechanical pulp according to claim 1, characterized in that, in the pulping step, the parameters of the grinding teeth of the grinding disc are set as follows: tooth width of 2.2-2.5 mm, groove width of 3.0-3.5 mm, and tooth height of 8-9 mm.

[0008] 3. The process for preparing a cardboard core layer by fine grinding of chemical pulp according to claim 1, characterized in that, in the mixing step, the chemical pulp is a long-fiber chemical pulp.

[0009] 4. The process for preparing a cardboard core layer by grinding chemical pulp according to claim 1, characterized in that, in the mixing step, the chemical pulp is a short fiber chemical pulp.

[0010] The beneficial effects of this invention are as follows: This patent mainly studies the fine refining technology of chemimechanical pulp for the core layer of white cardboard and food-grade cardboard. It utilizes a dual-disc mill to process the chemimechanical pulp separately, performing fine refining treatment on the self-made chemimechanical pulp to make the chemimechanical pulp fibers finer and more fully separated into fibers. The finely refined chemimechanical pulp is added to the core layer through stable pulping and is uniformly mixed with the unrefined chemimechanical pulp and waste pulp to balance the fiber length and degree of separation, thereby improving the fiber interweaving ability of the core layer, making the fiber interweaving tighter, thereby enhancing the bonding force between fibers, improving fiber bonding strength and folding endurance.

[0011] For producing white cardboard, adding refined long-fiber chemical pulp to the core layer costs over 3000 yuan / ton more (air-dried pulp) than adding the same amount of self-made refined chemimechanical pulp. The treated refined chemimechanical pulp replaces 5-12% of the long-fiber refined pulp, resulting in paper strength comparable to its original strength. For producing food-grade cardboard, adding refined short-fiber chemical pulp to the core layer costs over 1700 yuan / ton (air-dried pulp) more than adding the same amount of self-made refined chemimechanical pulp. The treated refined chemimechanical pulp replaces 5-12% of the short-fiber refined pulp, resulting in paper strength comparable to its original strength. Adding 5-15% refined chemimechanical pulp to the core layer, along with 50-70% chemimechanical pulp and 10-25% waste pulp, enhances fiber bonding and paper strength. During the fine refining process, the chemimechanical pulp fibers have increased hydroxyl group exposure, improving core layer interlayer bonding strength and folding endurance, while simultaneously reducing raw material costs.

[0012] This invention provides a process for preparing the core layer of cardboard by finely refining chemimechanical pulp. By finely refining a portion of the chemimechanical pulp in the core layer, it can replace either long-fiber or short-fiber chemical pulp. This fine refining process results in finer fibers and more complete fiber separation. The refined chemimechanical pulp is then added to the core layer and uniformly mixed with unrefined chemimechanical pulp and waste pulp to balance fiber length and fiber separation, thereby improving the fiber interweaving ability of the core layer, making the fibers more tightly interwoven, enhancing inter-fiber bonding strength, and increasing fiber bond strength and folding endurance. Compared to existing technologies, this process can significantly reduce production costs while maintaining the performance of the cardboard. Attached Figure Description

[0013] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0014] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to embodiments and accompanying drawings. The content mentioned in the embodiments is not intended to limit the present invention. The present invention will be described in detail below with reference to the accompanying drawings.

[0015] This embodiment provides a process for preparing a cardboard core layer by finely refining chemimechanical pulp. By finely refining a portion of the chemimechanical pulp in the core layer, it can replace either long-fiber or short-fiber chemical pulp. This fine refining process results in finer fibers and more complete fiber separation. The refined chemimechanical pulp is then added to the core layer and uniformly mixed with unrefined chemimechanical pulp and waste pulp to balance fiber length and fiber separation, thereby improving the fiber interweaving ability of the core layer, making the fibers more tightly interwoven, enhancing inter-fiber bonding strength, and increasing fiber bond strength and folding endurance. Compared to existing technologies, this process can significantly reduce production costs while maintaining the performance of the cardboard.

[0016] Example 1 In this embodiment, the process for preparing the cardboard core layer includes the following steps: Pulping is performed using a chemimechanical pulp production line. The chemimechanical pulp is then fed into a dual-disc mill. In this step, the pulp concentration is 5%, thus completing the pulp supply step. Subsequently, the dual-disc mill performs fine grinding of the chemimechanical pulp. At this time, the pulp freeness is set to 180 csf, and the pulp is ground using 46-inch grinding discs. The parameters of the grinding disc teeth are set as follows: tooth width 2.3 mm, groove width 3.3 mm, and tooth height 8 mm. In the pulping step, by setting the parameters of the grinding teeth, the fibers of the chemimechanical pulp can be further processed, causing them to loosen, appropriately cut, and flocculentize. In this embodiment, the flocculentization rate reaches 87%. Afterward, the refined chemimechanical pulp is transported to the core layer mixing tank and mixed with the chemimechanical pulp, waste pulp, and chemical pulp in the core layer mixing tank to form a mixed pulp. The ratio of the refined chemimechanical pulp, chemimechanical pulp, and waste pulp is 5%:50%:10%, with the remainder being chemical pulp. After the mixed pulp is fully mixed, it is transported to the PM32 paper machine for papermaking, thereby producing the cardboard core layer.

[0017] The cardboard core layer preparation process provided in this embodiment, which involves finely grinding a portion of the chemimechanical pulp, enables the pulp to become finer and more fibrous, while also achieving more complete fiber splitting. After thoroughly mixing the finely ground chemimechanical pulp with ordinary chemimechanical pulp, waste pulp, and chemical pulp, the fiber length and fiber splitting rate can be balanced, thereby improving the fiber interweaving ability of the core layer, making the fiber interweaving tighter, and thus enhancing the inter-fiber bonding force, improving fiber bonding strength and folding endurance.

[0018] In this embodiment, when producing white cardboard, the chemical pulp used in the mixing step is short-fiber chemical pulp. That is, in this technical solution, refined mechanical pulp replaces 5-12% of long-fiber chemical pulp in the prior art. The strength of the finished paper is comparable to that before, and the bulk, uniformity, and stiffness are also maintained. However, the production cost is significantly reduced. In the prior art, when long-fiber chemical pulp is added, the cost of chemical pulp is 3,000 yuan / ton (air-dried pulp). This technical solution can greatly reduce the production cost.

[0019] In the food-grade paperboard production process, the chemical pulp used in the mixing step is long-fiber chemical pulp. This means that in this technical solution, finely ground chemimechanical pulp replaces the existing 5-12% short-fiber chemical pulp. The paper strength is comparable to that before use, while enhancing interfiber bonding and overall paper strength. In existing technologies, adding the same amount of short-fiber chemical pulp costs approximately 1700 yuan / ton. Replacing it with finely ground chemimechanical pulp ensures high bulk, uniformity, and stiffness, while also providing higher bonding strength and folding endurance. During the fine grinding process, the chemimechanical pulp fibers have increased hydroxyl group exposure, improving core layer interlayer bonding strength and folding endurance, while simultaneously reducing raw material costs.

[0020] Implementation 2 In this embodiment, the main steps are largely the same as in the previous embodiment, with adjustments made to specific process steps to achieve better performance.

[0021] Specifically, in this embodiment, the process for preparing the cardboard core layer includes the following steps: Pulping is performed using a chemimechanical pulp production line. The chemimechanical pulp is then fed into a dual-disc mill. In this step, the feed pulp concentration is 4.5%, thus completing the pulp supply step. Subsequently, the dual-disc mill performs fine grinding of the chemimechanical pulp. At this time, the pulp freeness is set to 180 csf, and 46-inch grinding discs are used to grind the pulp. The grinding disc tooth parameters are set as follows: tooth width 2.2 mm, groove width 3.5 mm, and tooth height 9 mm. In the pulping step, by setting the parameters of the grinding teeth, the fibers of the chemimechanical pulp can be further processed, causing them to loosen, appropriately cut, and flocculentize. In this embodiment, the flocculentization rate reaches 89%. Afterward, the refined chemimechanical pulp is transported to the core layer mixing tank and mixed with the chemimechanical pulp, waste pulp, and chemical pulp in the core layer mixing tank to form a mixed pulp. The ratio of the refined chemimechanical pulp, chemimechanical pulp, and waste pulp is 10%:75%:10%, with the remainder being chemical pulp. After the mixed pulp is fully mixed, it is transported to the PM32 paper machine for papermaking, thereby producing the cardboard core layer.

[0022] The cardboard core layer preparation process provided in this embodiment, which involves finely grinding a portion of the chemimechanical pulp, enables the pulp to become finer and more fibrous, while also achieving more complete fiber splitting. After thoroughly mixing the finely ground chemimechanical pulp with ordinary chemimechanical pulp, waste pulp, and chemical pulp, the fiber length and fiber splitting rate can be balanced, thereby improving the fiber interweaving ability of the core layer, making the fiber interweaving tighter, and thus enhancing the inter-fiber bonding force, improving fiber bonding strength and folding endurance.

[0023] In this embodiment, when producing white cardboard, the chemical pulp used in the mixing step is short-fiber chemical pulp. That is, in this technical solution, refined mechanical pulp replaces 5-12% of long-fiber chemical pulp in the prior art. The strength of the finished paper is comparable to that before, and the bulk, uniformity, and stiffness are also maintained. However, the production cost is significantly reduced. In the prior art, when long-fiber chemical pulp is added, the cost of chemical pulp is 3,000 yuan / ton (air-dried pulp). This technical solution can greatly reduce the production cost.

[0024] In the food-grade paperboard production process, the chemical pulp used in the mixing step is long-fiber chemical pulp. This means that in this technical solution, finely ground chemimechanical pulp replaces the existing 5-12% short-fiber chemical pulp. The paper strength is comparable to that before use, while enhancing interfiber bonding and overall paper strength. In existing technologies, adding the same amount of short-fiber chemical pulp costs approximately 1700 yuan / ton. Replacing it with finely ground chemimechanical pulp ensures high bulk, uniformity, and stiffness, while also providing higher bonding strength and folding endurance. During the fine grinding process, the chemimechanical pulp fibers have increased hydroxyl group exposure, improving core layer interlayer bonding strength and folding endurance, while simultaneously reducing raw material costs.

[0025] Implementation Three In this embodiment, the main steps are largely the same as in the previous embodiment, with adjustments made to specific process steps to achieve better performance.

[0026] Specifically, in this embodiment, the process for preparing the cardboard core layer includes the following steps: Pulping is performed using a chemimechanical pulp production line. The chemimechanical pulp is then fed into a dual-disc mill. In this step, the feed pulp concentration is 5.5%, thus completing the pulp supply step. Subsequently, the dual-disc mill performs fine grinding of the chemimechanical pulp. At this time, the pulp freeness is set to 220 csf, and 46-inch grinding discs are used to grind the pulp. The grinding disc tooth parameters are set as follows: tooth width 2.5 mm, groove width 3.5 mm, and tooth height 3 mm. In the pulping step, by setting the parameters of the grinding teeth, the fibers of the chemimechanical pulp can be further processed, causing them to loosen, appropriately cut, and flocculentize. In this embodiment, the flocculentization rate reaches 88%. Afterward, the refined chemimechanical pulp is transported to the core layer mixing tank and mixed with the chemimechanical pulp, waste pulp, and chemical pulp in the core layer mixing tank to form a mixed pulp. The ratio of the refined chemimechanical pulp, chemimechanical pulp, and waste pulp is 15%:55%:25%, with the remainder being chemical pulp. After the mixed pulp is fully mixed, it is transported to the PM32 paper machine for papermaking, thereby producing the cardboard core layer.

[0027] The cardboard core layer preparation process provided in this embodiment, which involves finely grinding a portion of the chemimechanical pulp, enables the pulp to become finer and more fibrous, while also achieving more complete fiber splitting. After thoroughly mixing the finely ground chemimechanical pulp with ordinary chemimechanical pulp, waste pulp, and chemical pulp, the fiber length and fiber splitting rate can be balanced, thereby improving the fiber interweaving ability of the core layer, making the fiber interweaving tighter, and thus enhancing the inter-fiber bonding force, improving fiber bonding strength and folding endurance.

[0028] In this embodiment, when producing white cardboard, the chemical pulp used in the mixing step is short-fiber chemical pulp. That is, in this technical solution, refined mechanical pulp replaces 5-12% of long-fiber chemical pulp in the prior art. The strength of the finished paper is comparable to that before, and the bulk, uniformity, and stiffness are also maintained. However, the production cost is significantly reduced. In the prior art, when long-fiber chemical pulp is added, the cost of chemical pulp is 3,000 yuan / ton (air-dried pulp). This technical solution can greatly reduce the production cost.

[0029] In the food-grade paperboard production process, the chemical pulp used in the mixing step is long-fiber chemical pulp. This means that in this technical solution, finely ground chemimechanical pulp replaces the existing 5-12% short-fiber chemical pulp. The paper strength is comparable to that before use, while enhancing interfiber bonding and overall paper strength. In existing technologies, adding the same amount of short-fiber chemical pulp costs approximately 1700 yuan / ton. Replacing it with finely ground chemimechanical pulp ensures high bulk, uniformity, and stiffness, while also providing higher bonding strength and folding endurance. During the fine grinding process, the chemimechanical pulp fibers have increased hydroxyl group exposure, improving core layer interlayer bonding strength and folding endurance, while simultaneously reducing raw material costs.

[0030] Implementation 4 In this embodiment, the main steps are largely the same as in the previous embodiment, with adjustments made to specific process steps to achieve better performance.

[0031] Specifically, in this embodiment, the process for preparing the cardboard core layer includes the following steps: Pulping is performed using a chemimechanical pulp production line. The chemimechanical pulp is then fed into a dual-disc mill. In this step, the pulp concentration is 5%, thus completing the pulp supply step. Subsequently, the dual-disc mill performs fine grinding of the chemimechanical pulp. At this time, the pulp freeness is set to 200 csf, and the pulp is ground using 46-inch grinding discs. The grinding disc teeth are configured with the following parameters: tooth width of 2.4 mm, groove width of 3.2 mm, and tooth height of 8 mm. In the pulping step, by setting the parameters of the grinding teeth, the fibers of the chemimechanical pulp can be further processed, causing them to loosen, appropriately cut, and flocculentize. In this embodiment, the flocculentization rate reaches 89%. Afterward, the refined chemimechanical pulp is transported to the core layer mixing tank and mixed with the chemimechanical pulp, waste pulp, and chemical pulp in the core layer mixing tank to form a mixed pulp. The ratio of the refined chemimechanical pulp, chemimechanical pulp, and waste pulp is 12%:60%:20%, with the remainder being chemical pulp. After the mixed pulp is fully mixed, it is transported to the PM32 paper machine for papermaking, thereby producing the cardboard core layer.

[0032] The cardboard core layer preparation process provided in this embodiment, which involves finely grinding a portion of the chemimechanical pulp, enables the pulp to become finer and more fibrous, while also achieving more complete fiber splitting. After thoroughly mixing the finely ground chemimechanical pulp with ordinary chemimechanical pulp, waste pulp, and chemical pulp, the fiber length and fiber splitting rate can be balanced, thereby improving the fiber interweaving ability of the core layer, making the fiber interweaving tighter, and thus enhancing the inter-fiber bonding force, improving fiber bonding strength and folding endurance.

[0033] In this embodiment, when producing white cardboard, the chemical pulp used in the mixing step is short-fiber chemical pulp. That is, in this technical solution, refined mechanical pulp replaces 5-12% of long-fiber chemical pulp in the prior art. The strength of the finished paper is comparable to that before, and the bulk, uniformity, and stiffness are also maintained. However, the production cost is significantly reduced. In the prior art, when long-fiber chemical pulp is added, the cost of chemical pulp is 3,000 yuan / ton (air-dried pulp). This technical solution can greatly reduce the production cost.

[0034] In the food-grade paperboard production process, the chemical pulp used in the mixing step is long-fiber chemical pulp. This means that in this technical solution, finely ground chemimechanical pulp replaces the existing 5-12% short-fiber chemical pulp. The paper strength is comparable to that before use, while enhancing interfiber bonding and overall paper strength. In existing technologies, adding the same amount of short-fiber chemical pulp costs approximately 1700 yuan / ton. Replacing it with finely ground chemimechanical pulp ensures high bulk, uniformity, and stiffness, while also providing higher bonding strength and folding endurance. During the fine grinding process, the chemimechanical pulp fibers have increased hydroxyl group exposure, improving core layer interlayer bonding strength and folding endurance, while simultaneously reducing raw material costs.

[0035] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments without departing from the scope of the present invention and based on the present invention shall fall within the scope of the present invention.

Claims

1. A process for preparing a cardboard core layer by fine grinding of chemimechanical pulp, comprising the step of preparing chemimechanical pulp through a chemimechanical pulp production line, characterized in that, It also includes the following steps: The chemimechanical pulp production line supplies chemimechanical pulp to the dual-disc mill, and the feed pulp concentration is set to 4.5-5.5%. The chemimechanical pulp is finely ground using a dual-disc mill with a pulp freeness set to 180-220 csf and the dual-disc mill is equipped with 46-inch grinding discs to obtain a finely ground chemimechanical pulp. Mixing involves conveying the refined chemimechanical pulp to the core mixing tank, where it is mixed with the chemimechanical pulp, waste pulp, and chemical pulp to form a mixed pulp. The ratio of the refined chemimechanical pulp, chemimechanical pulp, and waste pulp is 5-15%: 50-70%: 10-25%, with the remainder being chemical pulp. Papermaking involves feeding the mixed pulp to the PM32 paper machine for papermaking.

2. The process for preparing a cardboard core layer by fine grinding of chemimechanical pulp according to claim 1, characterized in that, In the grinding step, the parameters of the grinding wheel teeth are set as follows: tooth width is 2.2-2.5mm, groove width is 3.0-3.5mm, and tooth height is 8-9mm.

3. The process for preparing a cardboard core layer by fine grinding of chemimechanical pulp according to claim 1, characterized in that, In the mixing step, the chemical pulp is a long-fiber chemical pulp.

4. The process for preparing a cardboard core layer by grinding chemimechanical pulp according to claim 1, characterized in that, In the mixing step, the chemical pulp is a short fiber chemical pulp.

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