Lyocell fiber bamboo pulp, and preparation method and application thereof

Abstract

This application relates to a method for preparing lyocell fiber bamboo pulp, comprising: (1) preparing bamboo strips; (2) loading bamboo strips into a cooking pot and preheating; (3) heating and cooking: pumping cold white liquor and warm black liquor from the bottom of the cooking pot to raise the temperature inside the pot to 100-120°C; pumping cold white liquor and warm black liquor from the bottom of the pot to raise the temperature inside the pot to 120-130°C; pumping hot white liquor and hot black liquor from the bottom of the pot to raise the temperature inside the pot to 155-160°C; and passing hot steam to raise the temperature inside the pot to 165-170°C; (4) removing the pulp from the pot; (5) bleaching; (6) acid treatment and washing; (7) purification; and (8) papermaking. This method for preparing lyocell fiber bamboo pulp uses sulfate displacement cooking to remove most of the lignin and hemicellulose from bamboo, eliminating the commonly used pre-hydrolysis step and avoiding the environmental pressure caused by odor treatment during the pre-hydrolysis process. It also significantly shortens the preparation time of bamboo pulp and saves a considerable amount of energy compared to the pre-hydrolysis method. This application also provides a bamboo pulp and its application.

Description

Technical Field

[0001] This application relates to a lyocell fiber bamboo pulp, its preparation method, and its application. Background Technology

[0002] Lyocell fiber is one of the green fibers of the 21st century. Conventional lyocell fiber is mainly made from wood raw materials. The wood pulp obtained through refining is then dissolved directly into a cellulose solution using NMMO (N-methylmorpholine-N-oxide) as a solvent without chemical reaction, and then filaments are produced.

[0003] In recent years, research and development of bamboo lyocell fiber has emerged. Compared with ordinary viscose fiber bamboo pulp, lyocell fiber bamboo pulp requires better reaction uniformity and lower metal ion content. Existing lyocell fiber bamboo pulp preparation processes all combine pre-hydrolysis and cooking to remove lignin and hemicellulose from the raw materials, while adjusting the degree of polymerization of the product. However, the pre-hydrolysis process inevitably produces furfural odor, and currently there is no good odor treatment system that can achieve 100% treatment of pre-hydrolysis odor. Therefore, the existing lyocell fiber bamboo pulp preparation processes pose a significant environmental risk. Summary of the Invention

[0004] The purpose of this application is to provide a method for preparing lyocell fiber bamboo pulp to overcome the high environmental risk of existing pre-hydrolysis processes and achieve clean and efficient production of bamboo resources.

[0005] This application provides a method for preparing lyocell fiber bamboo pulp, comprising the following steps: (1) Material preparation: bamboo slices are made and the bamboo slices are washed with a water washing machine to remove surface impurities; (2) Loading and preheating: Load the bamboo strips into the steaming pot, and add diluted black liquid while loading to preheat the bamboo strips; (3) Heating and steaming: a. Initial heating: Cold white liquor and warm black liquor are pumped into the bottom of the cooking pot to heat the bamboo strips for the first time, so that the temperature inside the pot rises to 100-120℃; b. Secondary heating: Pump cold white liquor and warm black liquor into the bottom of the pot to heat the material slices a second time, so that the temperature inside the pot rises to 120-130℃ and is held for 10-30 minutes. c. Reheating: Pump hot white liquid and hot black liquid into the pot from the bottom to raise the temperature inside the pot to 155-160℃; continue to pass hot steam to raise the temperature inside the pot to 165-170℃, and keep it at this temperature for 100-120 minutes. (4) Place in a pot: to obtain a slurry; (5) Bleaching: The slurry is bleached through the O-DO-EOP-D1 process; (6) Acid treatment and washing: The bleached pulp is subjected to acid treatment and washing processes in sequence to obtain bleached pulp; (7) Purification: The bleaching slurry is purified by passing it through a multi-stage sand remover; (8) Papermaking: The purified bleached pulp is papermade by a pulping machine to obtain bamboo pulp.

[0006] As a further improvement to the above scheme, the temperature of the cold white liquor is 80-95℃, the temperature of the warm black liquor is 120-130℃, the temperature of the hot black liquor is 160-165℃, and the temperature of the hot white liquor is 110-130℃.

[0007] As a further improvement to the above scheme, the effective components of the cold white liquor and the hot white liquor are NaOH and Na2S, and the active alkali content is 90-100 g / L calculated as sodium oxide; the effective components of the warm black liquor and the hot black liquor are NaOH and Na2S, the residual alkali content of the warm black liquor is 10-15 g / L calculated as sodium oxide, and the residual alkali content of the hot black liquor is 13-18 g / L calculated as sodium oxide.

[0008] As a further improvement to the above scheme, in step (3) during the heating and cooking process, the liquid ratio is (3.8-4.5):1.

[0009] As a further improvement to the above scheme, in step (4), the kappa value of the slurry is controlled to be 10-12 and the degree of polymerization is 600-800.

[0010] As a further improvement to the above scheme, in the acid treatment process, dilute acid and chelating agent are added to the bleached slurry, so that the concentration of the slurry is 3%-5%, the concentration of dilute acid is 1-1.1 g / l, the amount of chelating agent is 0.5%-1%, the reaction temperature is 45-70℃, and the reaction time is 30-60 min. In the washing process, soft water is used for washing, and the temperature of the soft water is 30-50℃.

[0011] As a further improvement to the above scheme, the dilute acid is dilute hydrochloric acid; the pH value of the bleached slurry after the washing process is 6.5-7.

[0012] As a further improvement to the above scheme, in step (7), the bleaching slurry is purified by passing it through multiple low-concentration sand removers, and the slurry concentration is 0.6%-1.0%.

[0013] This application also provides a lyocell fiber bamboo pulp, which is prepared by any of the above-described methods for preparing lyocell fiber bamboo pulp.

[0014] This application also provides a method for applying the above-mentioned lyocell fiber bamboo pulp, wherein the bamboo pulp and wood pulp are mixed in a ratio of (4-8):(6-2), and then spun using NMMO new solvent to obtain lyocell fiber.

[0015] Compared with the prior art, the above-mentioned technical solution of this application has the following advantages: The method for preparing lyocell fiber bamboo pulp provided in this application uses sulfate replacement cooking to remove most of the lignin and hemicellulose in bamboo, eliminating the commonly used pre-hydrolysis step and avoiding the environmental pressure caused by odor treatment during the pre-hydrolysis process. At the same time, it significantly shortens the preparation time of bamboo pulp and saves a large amount of energy compared to the pre-hydrolysis method. This application also provides a bamboo pulp obtained by this method and its application. Detailed Implementation

[0016] The present application will now be described in detail so that its advantages and features can be more easily understood by those skilled in the art, thereby providing a clearer and more definite definition of the scope of protection of the present application.

[0017] This application provides a method for preparing lyocell fiber bamboo pulp, aiming to overcome the high environmental risk of the pre-hydrolysis process in existing lyocell fiber bamboo pulp preparation processes, and to achieve clean and efficient production of bamboo resources. This lyocell fiber bamboo pulp is used to prepare lyocell fiber.

[0018] This application provides a method for preparing lyocell fiber bamboo pulp, comprising the following steps: (1) Preparation: bamboo slices are made and the bamboo slices are washed with a water washing machine to remove surface impurities.

[0019] The preferred bamboo material is 2-3 year old Cihuang bamboo.

[0020] (2) Loading and preheating: Load the bamboo strips into the steaming pot, and add diluted black liquid while loading to preheat the bamboo strips.

[0021] In this step, the diluted black liquor soaks and preheats the bamboo strips in the pot to improve the efficiency of the subsequent cooking process. The temperature of the diluted black liquor is 65-85℃. It is the black liquor produced by washing pulp in the washing and bleaching section of the sulfate pulping process. Its effective components are NaOH and Na2S, and its residual alkali content is 10-15g / l calculated as sodium oxide.

[0022] (3) Heating and cooking: In this step, the sulfate-type alkaline cooking method is used to remove lignin and hemicellulose from bamboo chips by using the action of alkali, while retaining cellulose and reducing the binding force between fibers, thus weakening the binding force between fibers and causing them to dissociate into pulp.

[0023] The proposed method uses segmented heating and steaming. Attention should be paid to controlling the temperature and time of each segment to avoid damaging the cellulose in the bamboo.

[0024] a. Initial heating: Cold white liquor and warm black liquor are pumped into the bottom of the cooking pot to heat the bamboo strips for the first time, raising the temperature inside the pot to 100-120℃.

[0025] Furthermore, the temperature of the cold white liquor is 80-95℃, the effective components are NaOH and Na2S, and its active alkali content, calculated as sodium oxide, is 90-100 g / L; the warm black liquor is the black liquor produced in the displacement cooking and recovery stage of the sulfate pulping process, the temperature is 120-130℃, the effective components are NaOH and Na2S, and its residual alkali content, calculated as sodium oxide, is 10-15 g / L.

[0026] b. Secondary heating: Pump cold white liquor and warm black liquor into the pot from the bottom to heat the material slices a second time, raising the temperature inside the pot to 120-130℃ and holding it for 10-30 minutes.

[0027] Furthermore, the temperature of the cold white liquor is 80-95℃, the effective components are NaOH and Na2S, and its active alkali content, calculated as sodium oxide, is 90-100 g / L; the warm black liquor is the black liquor produced in the displacement cooking and recovery stage of the sulfate pulping process, the temperature is 120-130℃, the effective components are NaOH and Na2S, and its residual alkali content, calculated as sodium oxide, is 10-15 g / L.

[0028] c. Reheating: Pump hot white liquid and hot black liquid into the pot from the bottom to raise the temperature inside the pot to 155-160℃; continue to pass hot steam to raise the temperature inside the pot to 165-170℃, and keep warm for 100-120 minutes.

[0029] Furthermore, the temperature of the hot white liquor is 110-130℃, the effective components are NaOH and Na2S, and its active alkali content, calculated as sodium oxide, is 90-100 g / L; the hot black liquor is the black liquor produced in the displacement cooking and recovery stage of the sulfate pulping process, the temperature is 160-165℃, the effective components are NaOH and Na2S, and its residual alkali content, calculated as sodium oxide, is 13-18 g / L.

[0030] In the entire step (3), all three stages of heating and displacement cooking are full liquid phase cooking, and the liquid ratio of each stage of cooking is controlled at (3.8-4.5):1.

[0031] The liquid ratio refers to the ratio of the weight (kg or t) of the oven-dried raw material to the total volume (L or m3) of the cooking liquid.

[0032] The heating and cooking process is carried out in three stages: initial heating, secondary heating, and final heating. The medicine is added and the temperature is increased in each stage to ensure uniform penetration of the medicine and a gentle reaction process, thereby improving the uniformity of cooking. In addition, after each stage of reaction, the soluble substances (lignin and hemicellulose, etc.) are discharged to improve the effect and efficiency of the subsequent reaction and reduce the burden on the subsequent washing process.

[0033] (4) Put it in the pot: to get the slurry.

[0034] In this step, the kappa value of the slurry is controlled to be 10-12, and the degree of polymerization is controlled to be 600-800.

[0035] (5) Bleaching: Bleaching the slurry through the O-D0-EOP-D1 process.

[0036] This step further removes residual lignin and hemicellulose from the pulp, reduces the pulp's color, and transforms the natural wood-colored pulp into a white pulp.

[0037] (6) Acid treatment and washing: The bleached pulp is subjected to acid treatment and washing processes in sequence to obtain bleached pulp.

[0038] This step aims to remove residual alkali and metal ions and other impurities from the slurry.

[0039] Furthermore, in the acid treatment process, dilute acid and chelating agent are added to the slurry, wherein the treatment concentration of the slurry is 3%-5%, the concentration of the dilute acid is 1-1.1 g / L, the amount of chelating agent is 0.5%-1%, the reaction temperature is 45-70℃, and the reaction time is 30-60 min.

[0040] In the washing process, soft water is used for washing, and the temperature of the soft water is 30-50℃.

[0041] Furthermore, the dilute acid is dilute hydrochloric acid; the bleaching slurry obtained after the acid treatment and washing processes is a neutral slurry with a pH value of 6.5-7.

[0042] Furthermore, the chelating agent is any one of sodium hexametaphosphate, sodium tripolyphosphate, and sodium pyrophosphate.

[0043] (7) Purification: The bleached slurry is purified by passing it through a multi-stage sand remover.

[0044] Furthermore, in this step, the bleaching slurry is purified by passing it through multiple low-concentration sand removers, with an inlet slurry concentration of 0.6%-1.0%.

[0045] The multi-stage low-concentration desander can separate various impurities from the bleaching slurry, including light impurities and heavy slag, with high impurity removal efficiency. The purified bleaching slurry is ready to be conveyed to the pulp board machine for pulp board making.

[0046] Furthermore, the low-concentration sand separator is provided with at least two sections.

[0047] (8) Papermaking: The purified bleached pulp is papermade by a pulping machine to obtain bamboo pulp.

[0048] Furthermore, in this step, the online concentration of the bleached bamboo pulp is 1.3%-2.0%. In a preferred embodiment, the bamboo pulp is in roll form, wound by a rolling machine, with a basis weight of 600-800 g / m³. 2 .

[0049] Understandably, in other embodiments, the bamboo pulp obtained from papermaking may also exist in other forms, such as sheet-like forms, depending primarily on the convenience of downstream processing; the quantitative amount may also be less than 600 g / m³. 2 or higher than 800g / m 2 The amount is usually related to the pulping speed and drying capacity of the pulping machine.

[0050] In one embodiment, the bamboo pulp, which is rolled into rolls by a rolling machine, is then packaged by a slitting and rewinding machine to cut the bamboo pulp into rolls of predetermined specifications, which facilitates subsequent processing, feeding, storage, and transportation.

[0051] The method for preparing lyocell fiber bamboo pulp provided in this application uses sulfate replacement cooking to remove most of the lignin and hemicellulose in bamboo, eliminating the commonly used pre-hydrolysis step and avoiding the environmental pressure caused by odor treatment during the pre-hydrolysis process. At the same time, it significantly shortens the production time of bamboo pulp and saves a lot of energy compared to the pre-hydrolysis method, saving about 20% of energy compared to the pre-hydrolysis method.

[0052] Furthermore, the method for preparing lyocell fiber bamboo pulp provided in this application involves adjusting the degree of polymerization (DP) of the pulp to 600-800 through sulfate replacement cooking. Then, it undergoes a three-stage bleaching process (oxygen delignification, DO-EOP-D1) to further remove residual lignin, achieving a whiteness of over 85% ISO. Following this, an acid treatment process removes ash and iron to purify the pulp. Finally, a multi-stage desander further purifies the pulp, resulting in a final bamboo pulp product with a DP of 500-650, a methyl cellulose content of over 92%, iron ions below 15 mg / kg, ash content below 0.1%, and copper ions below 0.5 mg / kg. This raw material is sufficient for the subsequent preparation of lyocell fiber.

[0053] This application also provides a lyocell fiber bamboo pulp, which is prepared by the above-described method for preparing lyocell fiber bamboo pulp.

[0054] The degree of polymerization of this lyocell fiber bamboo pulp is 500-650, the whiteness is above 85% ISO, the methyl cellulose content is not less than 92%, the iron ion content is not higher than 15mg / kg, the ash content is not higher than 0.1%, and the copper ion content is not higher than 0.5mg / kg. As a raw material, it can meet the requirements for the preparation of subsequent lyocell fibers.

[0055] Through long-term research, the inventors of this application have discovered that mixing bamboo pulp and wood pulp in a predetermined ratio, and then using NMMO solvent spinning technology, can significantly reduce the requirements for pentosan content in bamboo pulp compared to pure bamboo pulp raw materials (5%-10% pentosan content in bamboo pulp can also meet the requirements). The high-efficiency, low-cost bamboo pulp provided in this application for manufacturing lyocell fiber using bamboo-wood mixed pulp NMMO solvent spinning technology is an effective measure. By mixing bamboo and wood pulp, the goal of reducing costs and increasing efficiency in lyocell fiber manufacturing can be achieved, while also opening up new areas for the application of bamboo resources, and has broad application prospects.

[0056] This application also provides a method for applying the above-mentioned lyocell fiber bamboo pulp, specifically: mixing the bamboo pulp and wood pulp in a ratio of (4-8):(6-2), and then spinning them using a new NMMO solvent spinning process to obtain lyocell fiber.

[0057] In this application, the entire production process exhibits good spinning properties and the spinning quality meets the first-class standard for cotton-type lyocell staple fiber.

[0058] The present invention will be further described in detail below with reference to the embodiments. It should be particularly noted that the following embodiments are for illustrative purposes only and do not limit the scope of the invention. Similarly, the following embodiments are only some embodiments of this application and not all embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0059] Example 1: This embodiment provides a method for preparing bamboo pulp, including the following steps: (1) Preparation: bamboo slices are made and the bamboo slices are washed with a water washing machine to remove surface impurities.

[0060] The bamboo used is 2-year-old Cihuang bamboo.

[0061] (2) Loading and preheating: Load the bamboo strips into the steaming pot, and add diluted black liquid while loading to preheat the bamboo strips.

[0062] The temperature of the dilute black liquor is 80°C, and it is black liquor produced by the sulfate pulping method.

[0063] (3) Heating and steaming: a. Initial heating: Cold white liquor and warm black liquor are pumped into the bottom of the cooking pot to heat the bamboo strips for the first time, with a liquor ratio of 4:1, so that the temperature inside the pot rises to 110℃.

[0064] The cold white liquor has a temperature of 90°C, and its active ingredients are NaOH and Na2S. Its active alkali content, calculated as sodium oxide, is 100 g / L. The warm black liquor is black liquor produced by the sulfate pulping method, with a temperature of 130°C. Its active ingredients are NaOH and Na2S. Its residual alkali content, calculated as sodium oxide, is 15 g / L.

[0065] b. Secondary heating: Cold white liquor and warm black liquor are pumped into the bottom of the pot to heat the material flakes a second time, with a liquor ratio of 4.5:1, so that the temperature inside the pot rises to 130℃ and is held for 30 minutes.

[0066] Furthermore, the temperature of the cold white liquor is 95°C, the effective components are NaOH and Na2S, and its active alkali content is 100g / l (calculated as sodium oxide); the warm black liquor is black liquor produced by the sulfate pulping method, the temperature is 130°C, the effective components are NaOH and Na2S, and its residual alkali content is 15g / l (calculated as sodium oxide).

[0067] c. Reheating: Pump hot white liquid and hot black liquid into the pot from the bottom at a ratio of 4:1 to raise the temperature inside the pot to 160°C; continue to pass hot steam to raise the temperature inside the pot to 170°C and keep it at that temperature for 120 minutes.

[0068] Furthermore, the temperature of the hot white liquor is 130°C, the effective components are NaOH and Na2S, and its active alkali content is 100g / l (calculated as sodium oxide); the hot black liquor is black liquor produced by the sulfate pulping method, the temperature is 165°C, the effective components are NaOH and Na2S, and its residual alkali content is 18g / l (calculated as sodium oxide).

[0069] (4) Put it in the pot: to get the slurry.

[0070] In this step, the kappa value of the slurry is further controlled to be 10, and the degree of polymerization is 650.

[0071] (5) Bleaching: Bleaching the slurry through the O-D0-EOP-D1 process.

[0072] (6) Acid treatment and washing: The bleached pulp is subjected to acid treatment and washing processes in sequence to obtain bleached pulp.

[0073] In the acid treatment process, dilute hydrochloric acid and a chelating agent are added to the slurry, wherein the treatment concentration of the slurry is 5%, the concentration of the dilute acid is 1.1 g / L, the amount of chelating agent is 1%, the reaction temperature is 70℃, and the reaction time is 60 min.

[0074] The washing process uses soft water at a temperature of 50°C.

[0075] The bleached slurry obtained after acid treatment and washing processes has a pH value of 7.

[0076] Furthermore, the chelating agent is sodium hexametaphosphate.

[0077] (7) Purification: The bleached slurry is purified by passing it through two low-concentration sand removers, and the slurry concentration is 1.0%.

[0078] (8) Papermaking: The purified bleached pulp is papermade by a pulping machine to obtain bamboo pulp 1.

[0079] Furthermore, the online concentration of the bleached bamboo pulp is 2.0%, and the bamboo pulp 1 is in the form of a roll, which is rolled by a rolling machine, with a quantitative amount of 800g / m2.

[0080] The degree of polymerization of this bamboo pulp 1 is 550, whiteness is 88% ISO, methyl cellulose content is 92%, iron ion content is 12 mg / kg, ash content is 0.06%, copper ion content is 0.2 mg / kg, and pentosan content is 5.3%.

[0081] After mixing bamboo pulp 1 and wood pulp at a ratio of 8:2, the mixture is spun using a new NMMO solvent spinning process. The entire production process exhibits good spinning and spinnability, and the resulting lyocell fiber 1 achieves the first-class standard for cotton-type lyocell staple fiber.

[0082] Example 2: This embodiment provides a method for preparing bamboo pulp, including the following steps: (1) Preparation: bamboo slices are made and the bamboo slices are washed with a water washing machine to remove surface impurities.

[0083] The preferred bamboo material is 3-year-old Cihuang bamboo.

[0084] (2) Loading and preheating: Load the bamboo strips into the steaming pot, and add diluted black liquid while loading to preheat the bamboo strips.

[0085] The temperature of the dilute black liquor is 65°C, and it is black liquor produced by the sulfate pulping method.

[0086] (3) Heating and steaming: a. Initial heating: Cold white liquor and warm black liquor are pumped into the bottom of the cooking pot to heat the bamboo strips for the first time, with a liquor ratio of 4:1, so that the temperature inside the pot rises to 100℃.

[0087] Furthermore, the temperature of the cold white liquor is 80°C, the effective components are NaOH and Na2S, and its active alkali content is 90g / l (calculated as sodium oxide); the warm black liquor is black liquor produced by the sulfate pulping method, the temperature is 120°C, the effective components are NaOH and Na2S, and its residual alkali content is 10g / l (calculated as sodium oxide).

[0088] b. Secondary heating: Pump cold white liquor and warm black liquor from the bottom of the pot to heat the material flakes a second time at a liquor ratio of 3.8:1, raising the temperature inside the pot to 120℃ and holding it at that temperature for 20 minutes.

[0089] Furthermore, the temperature of the cold white liquor is 80°C, the effective components are NaOH and Na2S, and its active alkali content is 90g / l (calculated as sodium oxide); the warm black liquor is black liquor produced by the sulfate pulping method, the temperature is 120°C, the effective components are NaOH and Na2S, and its residual alkali content is 10g / l (calculated as sodium oxide).

[0090] c. Reheating: Pump hot white liquid and hot black liquid into the pot from the bottom at a ratio of 4.2:1 to raise the temperature inside the pot to 155°C; continue to pass hot steam to raise the temperature inside the pot to 165°C and keep it at that temperature for 100 minutes.

[0091] Furthermore, the temperature of the hot white liquor is 110°C, the effective components are NaOH and Na2S, and its active alkali content, calculated as sodium oxide, is 90 g / L; the hot black liquor is black liquor produced by the sulfate pulping method, the temperature is 160°C, the effective components are NaOH and Na2S, and its residual alkali content, calculated as sodium oxide, is 13 g / L.

[0092] (4) Put it in the pot: to get the slurry.

[0093] In this step, the kappa value of the slurry is further controlled to be 12 and the degree of polymerization to be 800.

[0094] (5) Bleaching: Bleaching the slurry through the O-D0-EOP-D1 process.

[0095] (6) Acid treatment and washing: The bleached pulp is subjected to acid treatment and washing processes in sequence to obtain bleached pulp.

[0096] In the acid treatment process, dilute acid and chelating agent are added to the slurry, wherein the treatment concentration of the slurry is 3%, the concentration of the dilute acid is 1 g / L, the amount of chelating agent is 0.5%, the reaction temperature is 45℃, and the reaction time is 30 min.

[0097] In the washing process, soft water at a temperature of 30℃ is used to wash the slurry.

[0098] Furthermore, the dilute acid is dilute hydrochloric acid; the bleaching slurry obtained after the acid treatment and washing processes has a pH value of 6.5.

[0099] Furthermore, the chelating agent is sodium tripolyphosphate.

[0100] (7) Purification: The bleached slurry is purified by passing it through a three-stage low-concentration sand remover, with an inlet slurry concentration of 0.6%.

[0101] (8) Papermaking: The purified bleached pulp is papermade by a pulping machine to obtain bamboo pulp 2.

[0102] Furthermore, the online concentration of the bleached bamboo pulp is 1.3%, and the bamboo pulp residue 2 is in the form of a roll, wound by a rolling machine, with a basis weight of 600g / m³. 2 .

[0103] The degree of polymerization of this bamboo pulp 2 is 600, whiteness is 85% ISO, methyl cellulose content is 94%, iron ion content is 14 mg / kg, ash content is 0.07%, copper ion content is 0.3 mg / kg, and pentosan content is 7.1%.

[0104] After mixing bamboo pulp 2 and wood pulp in a 4:6 ratio, the mixture is spun using a new NMMO solvent spinning process. The entire production process exhibits good spinning and spinnability, and the resulting lyocell fiber 2 achieves the first-class standard for cotton-type lyocell staple fiber.

[0105] Example 3: This embodiment provides a method for preparing bamboo pulp, including the following steps: (1) Preparation: bamboo slices are made and the bamboo slices are washed with a water washing machine to remove surface impurities.

[0106] The preferred bamboo material is 2-year-old Cihuang bamboo.

[0107] (2) Loading and preheating: Load the bamboo strips into the steaming pot, and add diluted black liquid while loading to preheat the bamboo strips.

[0108] The temperature of the dilute black liquor is 85°C, and it is black liquor produced by the sulfate pulping method.

[0109] (3) Heating and steaming: a. Initial heating: Cold white liquor and warm black liquor are pumped into the bottom of the cooking pot to heat the bamboo strips for the first time, with a liquor ratio of 4:1, so that the temperature inside the pot rises to 110℃.

[0110] Furthermore, the temperature of the cold white liquor is 85°C, the effective components are NaOH and Na2S, and its active alkali content is 95g / l (calculated as sodium oxide); the warm black liquor is black liquor produced by the sulfate pulping method, the temperature is 125°C, the effective components are NaOH and Na2S, and its residual alkali content is 12g / l (calculated as sodium oxide).

[0111] b. Secondary heating: Cold white liquor and warm black liquor are pumped into the bottom of the pot to heat the material flakes a second time, with a liquor ratio of 3.8:1, so that the temperature inside the pot rises to 125℃ and is held for 25 minutes.

[0112] Furthermore, the temperature of the cold white liquor is 85°C, the effective components are NaOH and Na2S, and its active alkali content is 95g / l (calculated as sodium oxide); the warm black liquor is black liquor produced by the sulfate pulping method, the temperature is 125°C, the effective components are NaOH and Na2S, and its residual alkali content is 12g / l (calculated as sodium oxide).

[0113] c. Reheating: Pump hot white liquid and hot black liquid into the pot from the bottom at a ratio of 4.5:1 to raise the temperature inside the pot to 158°C; continue to pass hot steam to raise the temperature inside the pot to 168°C and keep it at that temperature for 110 minutes.

[0114] Furthermore, the temperature of the hot white liquor is 120°C, the effective components are NaOH and Na2S, and its active alkali content, calculated as sodium oxide, is 92 g / L; the hot black liquor is black liquor produced by the sulfate pulping method, the temperature is 160°C, the effective components are NaOH and Na2S, and its residual alkali content, calculated as sodium oxide, is 15 g / L.

[0115] (4) Put it in the pot: to get the slurry.

[0116] In this step, the kappa value of the slurry is further controlled to be 10, and the degree of polymerization is 780.

[0117] (5) Bleaching: Bleaching the slurry through the O-D0-EOP-D1 process.

[0118] (6) Acid treatment and washing: The bleached pulp is subjected to acid treatment and washing processes in sequence to obtain bleached pulp.

[0119] In the acid treatment process, dilute acid and chelating agent are added to the slurry, wherein the treatment concentration of the slurry is 3.5%, the concentration of dilute acid is 1 g / L, the amount of chelating agent is 0.75%, the reaction temperature is 55℃, and the reaction time is 45 min.

[0120] In the washing process, soft water at a temperature of 40℃ is used to wash the slurry.

[0121] Furthermore, the dilute acid is dilute hydrochloric acid; the pH value of the bleached slurry obtained after the acid treatment and washing processes is 7.0.

[0122] Furthermore, the chelating agent is sodium pyrophosphate.

[0123] (7) Purification: The bleached slurry is purified by passing it through a three-stage low-concentration sand remover, with an inlet slurry concentration of 0.8%.

[0124] (8) Papermaking: The purified bleached pulp is papermade by a pulping machine to obtain bamboo pulp 3.

[0125] Furthermore, the online concentration of the bleached bamboo pulp is 1.5%, and the bamboo pulp 3 is in the form of a roll, which is rolled by a rolling machine, with a quantitative amount of 700g / m2.

[0126] The degree of polymerization of this bamboo pulp 3 is 550, whiteness is 86% ISO, methyl cellulose content is 94%, iron ion content is 12 mg / kg, ash content is 0.08%, copper ion content is 0.2 mg / kg, and pentosan content is 6.4%.

[0127] After mixing bamboo pulp 3 and wood pulp in a 5:5 ratio, the mixture is spun using a new NMMO solvent spinning process. The entire production process exhibits good spinning and spinnability, and the resulting lyocell fiber 3 achieves the first-class standard for cotton-type lyocell staple fiber.

[0128] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made using the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A process for the production of lyocell fiber bamboo pulp, characterized in that, Includes the following steps: (1) Material preparation: bamboo slices are made and the bamboo slices are washed with a water washing machine to remove surface impurities; (2) Loading and preheating: Load the bamboo strips into the steaming pot, and add diluted black liquid while loading to preheat the bamboo strips; (3) Heating and steaming: a. Initial heating: Cold white liquor and warm black liquor are pumped into the bottom of the cooking pot to heat the bamboo strips for the first time, so that the temperature inside the pot rises to 100-120℃; b. Secondary heating: Pump cold white liquor and warm black liquor into the bottom of the pot to heat the material slices a second time, so that the temperature inside the pot rises to 120-130℃ and is held for 10-30 minutes. c. Reheating: Pump hot white liquor and hot black liquor into the pot from the bottom to raise the pot temperature to 155-160℃; continue to pass hot steam to raise the pot temperature to 165-170℃ and hold for 100-120 minutes; wherein, the effective components of the cold white liquor and the hot white liquor are NaOH and Na2S, and the active alkali content is 90-100 g / L (calculated as sodium oxide); the effective components of the warm black liquor and the hot black liquor are NaOH and Na2S, the residual alkali content of the warm black liquor is 10-15 g / L (calculated as sodium oxide), and the residual alkali content of the hot black liquor is 13-18 g / L (calculated as sodium oxide); (4) Discharge into the pot: Obtain the slurry, and control the kappa value of the slurry to be 10-12 and the degree of polymerization to be 600-800; (5) Bleaching: The slurry is bleached through the O-DO-EOP-D1 process; (6) Acid treatment and washing: The bleached pulp is subjected to acid treatment and washing processes in sequence to obtain bleached pulp; (7) Purification: The bleaching slurry is purified by passing it through a multi-stage sand remover; (8) Papermaking: The purified bleached pulp is papermade by a pulping machine to obtain bamboo pulp.

2. The process for the production of lyocell fiber bamboo pulp according to claim 1, characterized in that, The temperature of the cold white liquor is 80-95℃, the temperature of the warm black liquor is 120-130℃, the temperature of the hot black liquor is 160-165℃, and the temperature of the hot white liquor is 110-130℃.

3. The process for the production of lyocell fiber bamboo pulp according to claim 1, characterized in that, In step (3), during the heating and cooking process, the liquid ratio is (3.8-4.5):

1.

4. The process for the production of lyocell fiber bamboo pulp according to claim 1, characterized in that, In the acid treatment process, dilute acid and chelating agent are added to the bleached slurry to make the slurry concentration 3%-5%, the dilute acid concentration 1-1.1 g / l, the chelating agent dosage 0.5%-1%, the reaction temperature 45-70℃, and the reaction time 30-60 min. In the washing process, soft water is used for washing, and the temperature of the soft water is 30-50℃.

5. The process for the production of lyocell fiber bamboo pulp according to claim 4, characterized in that, The dilute acid is dilute hydrochloric acid; the pH value of the bleached slurry after the washing process is 6.5-7.

6. The process for the production of lyocell fiber bamboo pulp according to claim 1, characterized in that, In step (7), the bleaching slurry is purified by passing it through a multi-stage low-concentration sand remover, and the slurry concentration is 0.6%-1.0%.

7. A lyocell fibre bamboo pulp, characterised in that, It is prepared by the method for preparing lyocell fiber bamboo pulp according to any one of claims 1-6.

8. A method of using lyocell fiber bamboo pulp according to claim 7, characterized in that, The bamboo pulp and wood pulp were mixed in a ratio of (4-8):(6-2) and then spun using NMMO new solvent to obtain lyocell fibers.