CN107663800B - Natural color poplar pulp and production process thereof - Google Patents
Natural color poplar pulp and production process thereof Download PDFInfo
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- CN107663800B CN107663800B CN201710913186.3A CN201710913186A CN107663800B CN 107663800 B CN107663800 B CN 107663800B CN 201710913186 A CN201710913186 A CN 201710913186A CN 107663800 B CN107663800 B CN 107663800B
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C5/00—Other processes for obtaining cellulose, e.g. cooking cotton linters ; Processes characterised by the choice of cellulose-containing starting materials
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/02—Washing ; Displacing cooking or pulp-treating liquors contained in the pulp by fluids, e.g. wash water or other pulp-treating agents
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
- D21D5/00—Purification of the pulp suspension by mechanical means; Apparatus therefor
- D21D5/02—Straining or screening the pulp
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F9/00—Complete machines for making continuous webs of paper
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- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
- D21H11/16—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only modified by a particular after-treatment
- D21H11/20—Chemically or biochemically modified fibres
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Abstract
The invention provides natural-color poplar pulp, which has the advantages of 28-30% of whiteness of the poplar pulp, 1.60-1.95 cm of bulk density 3/g and 15-25K of hardness. The invention also provides a preparation process of the natural color poplar pulp, which comprises a heat preservation step, wherein the heat preservation step comprises big air release; when the pressure of the steam ball is 0 in the large air release step, black liquor is injected into the steam ball; the amount of the black liquor injected into the steaming ball is 3-8 square/ball. The method fully utilizes the characteristic of low whiteness of the natural color poplar pulp, the black liquor after cooking can be recycled, the whole-process zero emission of the black liquor is realized, the uniformity of the prepared poplar pulp in different batches is improved, and the quality of a finished product is further improved; the natural color poplar pulp prepared by the method has higher tensile index and lower tearing index, is very suitable for producing and manufacturing the household paper, has natural color and style of wood, and has soft and natural hand feeling.
Description
Technical Field
The invention relates to wood pulp and a production process thereof, in particular to natural color poplar pulp and a production process thereof.
Background
At present, the common daily paper in the market is wood pulp paper, the wood pulp paper generally refers to paper made by using wood as a raw material through pulping, cooking, bleaching and other processes, and has the advantages of fine and soft paper, smooth surface, high whiteness and the like; however, because the wastewater produced in the production process pollutes the environment seriously, the organic chloride in the wastewater is the most toxic substance in the currently known organic compounds, and causes three causing effects, namely carcinogenesis, mutagenicity and teratogenicity, on all organisms.
The unbleached poplar pulp is chemical poplar pulp which is not bleached only by cooking, and no chemical bleaching agent is added, so the unbleached poplar pulp is an environment-friendly and sanitary original ecological unbleached pulp, and the unbleached poplar pulp does not pass through a bleaching procedure and does not generate carcinogens such as dioxin and the like, so the production of the unbleached poplar pulp has a wider market environment along with the gradual attention of people on environment-friendly products; meanwhile, the poplar is a fast-growing and high-yield tree species, has the characteristics of wide adaptability, long annual growth period, high production speed and the like, is widely planted in the south and the north of China, and has rich poplar resources, so that sustainable utilization raw materials are provided for the production of paper pulp; meanwhile, the poplar wood has the advantages of light weight, high strength, good elasticity, long fiber and high content.
Patent application No. 201610960356.9 discloses a bleaching-agent-free antibacterial physiological paper, which comprises a bleaching-free raw paper layer and an antibacterial layer sprayed on the bleaching-free raw paper layer, and the bleaching-free antibacterial physiological paper is prepared from more raw materials, is relatively complex, has higher cost and does not have the condition of mass production.
Patent No. CN201210170739.8, with patent names: the invention relates to a cooking process for composite modification of natural color bamboo pulp and natural color wood pulp into dissolving pulp, which is characterized in that bamboo pulp and wood pulp composite pulp are fed into a tubular continuous digester for cooking, a continuous cooking pipe of the continuous digester is set to be 3 sections, one section connected with a pre-reaction bin is provided with a T-shaped pipe for adding alkali liquor and a steam pipe for adding steam, the other two sections are provided with steam pipes for adding steam, and the cooking process has the following requirements: liquid ratio: 1: 2.0-4.0; adding alkali liquor according to 17-30% of absolute dry weight; the steam temperature of a section of the continuous steaming pipe connected with the pre-reaction bin is 105 +/-5 ℃; the steam temperature of the middle section is 140 +/-5 ℃; the temperature of the steam at the first section connected with the cold spraying device is 150-175 ℃; compression ratio: 1:2 to 3.0. The invention adopts different material preparation methods, and achieves the purpose of producing the natural-color wood pulp by compounding the bamboo pulp and the wood pulp, but the composite wood pulp prepared by the invention has the whiteness of more than 70 and still does not accord with the natural and retro style and aesthetic feeling of modern people.
In general, the current state of the art for the preparation of wood pulp has the following technical drawbacks:
1. the process is complex and the production cost is high;
2. the wood pulp prepared by the prior art has high whiteness, large vertical fluctuation and unstable whiteness upper and lower limits, and does not have natural and vintage styles;
3. in the pulping process of the prior art, the generated black liquor can not be recycled, thereby causing waste and environmental pollution;
4. in the prior art, the fact that the high-bulk natural color wood pulp is prepared by taking poplar as a raw material is not found for a while, and the main reason is that the bulk is difficult to improve because the natural color pulp in the prior art is not subjected to process treatment.
Disclosure of Invention
Aiming at the defects of the prior art, the first invention aims to provide the natural-color poplar pulp, and the natural-color poplar pulp prepared by the method meets the following indexes: the whiteness is 28-30%, and the bulk is 1.60-1.95 cm3The hardness of the dust is 15-25K, the ash content is less than or equal to 0.12 percent, and the dust is less than or equal to 100mm2/m2;
The second invention aims to provide a production process of natural colored poplar wood pulp, which comprises the following steps:
(1) and (3) cooking: conveying the poplar slices to a screw conveyor through a towing belt, and adding prepared alkali liquor and a cooking auxiliary agent into the middle section of the screw conveyor; after the poplar slices are uniformly mixed with alkali liquor and a cooking aid in a screw conveyor, putting the mixed poplar slices into a rotary spherical digester through a spherical digester, and cooking;
the poplar chips meet the following indexes: the water content is less than or equal to 25 percent, the thickness is 0.8-1.8 mm, and no impurities, barks or black rot exists.
The temperature of the alkali liquor added into the screw conveyor is 80-100 ℃;
wherein the ball throwing amount (air drying) of the poplar chips in the rotary spherical digester is 8.5-9.0 t/ball;
the amount of alkali used for cooking is 18-22%;
the ratio of the cooking liquor is 1: 2-4;
the dosage of the cooking auxiliary agent is 7-8 kg/ball; the cooking agent is novel anthraquinone, preferably produced by Henan Honorede new material science and technology limited company; the novel anthraquinone has the fineness of 100 meshes, the water content is less than or equal to 0.2 percent, the free quinone is more than or equal to 45 percent, the effective active substance is more than or equal to 53.5 percent, and the insoluble substance is less than or equal to 0.5 percent; the novel anthraquinone has strong wetting and penetrating capabilities, can promote caustic soda to quickly wet the surface of the fiber and penetrate into the fiber, accelerates the dissolution of colloid and the removal of lignin, and shortens the cooking time by 20-30%; the amount of papermaking black liquor is reduced by 10-20%, the amount of alkali is reduced by 5-10%, the pollution control cost is reduced, and the environment protection is facilitated;
the novel anthraquinone can form a polymer protective film on the surface of the fiber, can reduce the terminal group of carbohydrate into a primary alcohol group stable to alkali, thereby effectively inhibiting peeling reaction, protecting the fiber, effectively protecting the fiber, preventing the peeling reaction of the fiber, ensuring that the strength of the pulp fiber is high, reducing the pulp hardness by 2-6 manganese values, and simultaneously greatly improving the bulk of the fiber by combining the novel anthraquinone and the process of the invention.
The novel anthraquinone can effectively prevent silicon compounds and calcium-magnesium compounds from forming solids, thereby obviously reducing the scaling of an evaporator and a pipeline.
(2) And (3) heating: after the ball is filled, sealing the rotary spherical digester, and idling the rotary spherical digester for 5-20 min; preferably 10 min; then heating is carried out; the goal of the rotary motion of the rotary spherical digester is to further mix the poplar slices in the rotary spherical digester with alkali liquor and cooking aids;
the heating is carried out for one time, and small steam is released once in the middle of the heating process, so that the poplar pulp is convenient to heat;
the small steam release time is 5-10 min;
the pressure after the small steam release is 0.3-0.6 MPa; the temperature after the small steam release is 140-160 ℃;
the temperature rise time is controlled to be more than 50min, and the temperature is uniformly and slowly raised to 165-175 ℃; the temperature rise time is prolonged and the temperature rise is slow, so that the uniformity of wood chip cooking can be better ensured, and the bulk of the prepared natural color poplar pulp is further improved.
(3) And (3) heat preservation: after the temperature is increased, the boiling pressure is stabilized between 0.7 MPa and 0.75MPa, the spherical digester is subjected to heat preservation for 40-70 min, the pulp testing is started by using a pulp testing valve after the heat preservation is carried out for 30-50 min (preferably 40 min), and the steam is greatly released when the hardness of the pulp tested is in the range of 16K to 18K;
when the large exhaust gas is released until the pressure is 0, black liquor is injected into the ball; the temperature in the ball is rapidly reduced, the ball cover is convenient to open, and meanwhile, the pollution and the water waste are reduced;
and 3-8 square/ball of black liquor injected into the steaming ball, and opening the ball cover to pour the materials after cooling.
(4) Washing the pulp: after the pulp in the ball is poured into the ball lower tank, the concentration of the pulp is diluted to about 3% by using circulating black liquor, the pulp is beaten to a skip sieve by using a pulp pump to sieve out impurities such as wood knots, and the sieved pulp is washed by a front horizontal belt type pulp washer and a rear horizontal belt type pulp washer respectively;
controlling the residual alkali of the washed slurry to be below 0.2 g/l;
after the pulp is washed, one part of extracted black liquor is sent to alkali recovery; the circulation of a part of black liquor system is used for diluting the pulp and cooling the spherical digester.
(5) Removing impurities: removing impurities from the pulp by a pressure screen, sending the good pulp to a second-stage three-section slag remover for removing slag, and diluting and washing the pulp in a pulp tank after the slag is removed by a rotary screen thickener; the concentration of the diluted slurry is 2-4%, and the diluted slurry is sent to a pulp machine for papermaking;
the pressure of the pressure screen is 0.13-0.17 MPa;
the concentration of the concentrated slurry of the cylinder thickener is 8-12%.
(6) Manufacturing paper:
the papermaking comprises the working procedures of a pulp storage tank, a net part, a pressing part, a drying part, a paper cutting and arranging machine and weighing and packaging;
the pulp concentration of the pulp storage tank is 2.5-3%;
the concentration of the pulp on the net part is 1.2-1.5%, and the dryness of the pulp on the net part is more than 20%;
the press section comprises a first press area, a second press area and a third press area; the pressure of the first pressing area is 3.5-4.5 kg, and the pressure of the second pressing area is 4.5-5.5 kg; the pressure of the three-pressure area is 5.5-6.5 kg; the dryness of the pulp sheet discharged from the three-pressure area is more than 58 percent;
the air pressure of the drying part entering a drying cylinder is less than or equal to 0.4 MPa;
the water content of the pulp pages at the drying part is 10 +/-1.5%, and the quantitative rate is 700 +/-100 g per square meter.
Due to the adoption of the technical scheme, the invention achieves the technical effects that:
1. the method fully utilizes the characteristic of low whiteness of the grey pulp of the natural color, the black liquor after cooking can be recycled, part of the black liquor enters the alkali recovery, and the part of the black liquor is continuously washed next time, so that the whole-process zero emission of the black liquor is realized, the whiteness uniformity of the grey pulp of different batches of the prepared grey pulp is improved, and the quality of the finished pulp is further improved;
2. the natural color poplar pulp prepared by the method has higher tensile index and lower tearing index, is very suitable for producing and manufacturing the household paper, has natural color and style of wood, and has soft and natural hand feeling;
3. the finished product natural color poplar pulp prepared by the invention meets the following indexes: the whiteness is 28-30%, and the bulk is 1.60-1.95 cm3The hardness of the dust is 15-25K, the ash content is less than or equal to 0.12 percent, and the dust is less than or equal to 100mm2/m2(ii) a The whiteness directly reflects the style of the log and the appearance feeling of the prepared household paper, and when the whiteness is 28-30%, the prepared paper product is more fit with the natural style and charm;
4. the tensile index of the natural-color poplar pulp prepared by the method is higher and reaches 80.81-95.28 N.m/g, particularly, the tensile index of the natural-color poplar pulp prepared in the embodiment 3 is highest, and meanwhile, the tearing index is lower, so that the natural-color poplar pulp is more suitable for being used as paper for daily life;
5. the invention overcomes the defects of the prior art, and the prepared natural color poplar wood pulp has higher bulk and can reach as high as 1.95 cm3The volume of the bulk directly influences the subsequent processing performance of the finished poplar pulp board; meanwhile, the natural color poplar pulp prepared by the process has the advantages of coarse wet weight, long average fiber length and high fiber strength, and reduces the production cost of downstream products, and the cost of producing household paper and other paper products by using the poplar pulp prepared by the process is reduced by more than 20 percent per ton;
6. in the process of preparing the unbleached poplar wood pulp, the novel anthraquinone is adopted, the combination of the cooking process is optimized, and the black liquor is circularly controlled, so that the black liquor can be repeatedly used, the whole process of zero discharge of the black liquor can be achieved, and the environment-friendly concept of modern development is met;
7. the process for preparing the natural color poplar wood pulp is simple and can be used for mass production;
8. the process for preparing the natural color poplar wood pulp has no bleaching stage, and no organic chloride in the wastewater, so that the method does not cause environmental pollution and completely does not generate carcinogenesis and teratogenicity.
Detailed Description
The technical solutions of the present invention are described below clearly and completely through embodiments, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments, and all other technical solutions obtained by those skilled in the art without creative efforts based on the embodiments of the present invention belong to the protection scope of the present invention.
Example 1 production Process of unbleached poplar pulp
The method comprises the following steps:
the second invention aims to provide a production process of natural colored poplar wood pulp, which comprises the following steps:
(1) and (3) cooking: conveying the poplar slices to a screw conveyor through a towing belt, and adding prepared alkali liquor and a cooking auxiliary agent into the middle section of the screw conveyor; after the poplar slices are uniformly mixed with alkali liquor and a cooking aid in a screw conveyor, putting the mixed poplar slices into a rotary spherical digester through a spherical digester, and cooking;
the poplar chips meet the following indexes: water content is 22%, thickness is 0.8mm, and no impurity, bark or black rot exists.
The temperature of the alkali liquor added into the screw conveyor is 80 ℃;
wherein the ball throwing amount (air drying) of the poplar chips in the rotary spherical digester is 8.5 t/ball;
the amount of alkali used for cooking is 18 percent;
the ratio of the cooking liquor is 1: 2;
the dosage of the cooking auxiliary agent is 7.1 kg/ball; the novel anthraquinone cooking agent is preferably produced by Henan Honorede new material science and technology company; the novel anthraquinone has the fineness of 100 meshes, the water content is less than or equal to 0.2 percent, the free quinone is more than or equal to 45 percent, the effective active substance is more than or equal to 53.5 percent, and the insoluble substance is less than or equal to 0.5 percent;
(2) and (3) heating: after the ball is filled, the rotary spherical digester is covered, and the rotary spherical digester is idled for 5min and then heated; the goal of the rotary motion of the rotary spherical digester is to further mix the poplar slices in the rotary spherical digester with alkali liquor and cooking aids;
the heating is carried out for one time, and small steam is released once in the middle of the heating process, so that the poplar pulp is convenient to heat;
the temperature rise time is controlled to be 55min, and the temperature is uniformly and slowly raised to 175 ℃; the extension of the temperature rise time and the slow temperature rise can better ensure the uniformity of wood chip cooking, reduce the severe oxidation of cellulose caused by severe temperature rise, and further improve the bulk and tensile index of the prepared natural color poplar pulp.
The small steam release time is 5 min; the pressure after the small steam release is 0.6 MPa; the temperature after the small steam release is 160 ℃;
(3) and (3) heat preservation: after the temperature is increased, the boiling pressure is stabilized between 0.75MPa, the spherical digester is subjected to heat preservation for 50min, the pulp testing valve is used for testing the pulp after the heat preservation is carried out for 42min, and the steam is greatly released when the hardness of the pulp testing pulp is in the range of 16K;
when the large air is released until the pressure is 0, black liquor is injected into the ball; the temperature in the ball is rapidly reduced, the ball cover is convenient to open, and meanwhile, the pollution and the water waste are reduced;
the amount of black liquor injected into the steaming ball is 5 square/ball, and the ball cover is opened to pour the material after cooling.
(4) Washing the pulp: after the pulp in the ball is poured into the ball lower tank, the concentration of the pulp is diluted to about 3% by using circulating black liquor, the pulp is beaten to a skip sieve by using a pulp pump to sieve out impurities such as wood knots, and the sieved pulp is washed by a front horizontal belt type pulp washer and a rear horizontal belt type pulp washer respectively; controlling the residual alkali of the washed slurry to be below 0.2 g/l; after washing, sending a part of extracted black liquor to alkali recovery; a part of black liquor system is internally circulated with slurry dilution and spherical digester cooling; pulping after the pulp washing is finished, wherein the pulping degree is 18 DEG SR;
(5) removing impurities: removing impurities from the pulp by a pressure screen, sending the good pulp to a second-stage three-section slag remover for removing slag, and diluting and washing the pulp in a pulp tank after the slag is removed by a rotary screen thickener; the concentration of the diluted slurry is 2 percent, and the diluted slurry is sent to a pulp machine for papermaking;
the pressure of the pressure screen is 0.13 MPa;
the concentration of the concentrated slurry of the cylinder thickener is 8 percent.
(6) Manufacturing paper:
the paper making process comprises the working procedures of a pulp storage tank, a net part, a pressing part, a drying part, a paper cutting and arranging machine and weighing and packaging;
the pulp concentration of the pulp storage tank is 2.5-3%;
the concentration of the pulp on the net part is 1.5 percent, and the dryness of the pulp on the net part is more than 20 percent;
the press section comprises a first press area, a second press area and a third press area; the first nip pressure is 3.5kg and the second nip pressure is 5.5 kg; the triple nip pressure was 5.5 kg; the dryness of the pulp sheet in the third area is more than 58 percent;
the air pressure of the drying part entering a drying cylinder is less than or equal to 0.4 MPa;
the water content of the pulp sheets discharged from the drying part is 10.5%, and the quantitative rate is 750g per square meter.
Example 2 production Process of unbleached poplar pulp
The method comprises the following steps:
(1) and (3) cooking: conveying the poplar slices to a screw conveyor through a towing belt, and adding prepared alkali liquor and a cooking auxiliary agent into the middle section of the screw conveyor; after the poplar slices are uniformly mixed with alkali liquor and a cooking aid in a screw conveyor, putting the mixed poplar slices into a rotary spherical digester through a spherical digester, and cooking; the poplar chips meet the following indexes: the water content is 18 percent, the thickness is 1.2-1.5mm, and the paper has no impurities, barks and black rot; adding the alkali liquor into a screw conveyor at the temperature of 100 ℃; wherein the ball throwing amount (air drying) of the poplar chips in the rotary spherical digester is 9.0 t/ball; the amount of alkali used for cooking is 22 percent; the ratio of the cooking liquor is 1: 3;
the dosage of the cooking auxiliary agent is 7.5 kg/ball; the cooking agent is novel anthraquinone, preferably produced by Henan Honorede new material science and technology limited company; the novel anthraquinone has the fineness of 100 meshes, the water content is less than or equal to 0.2 percent, the free quinone is more than or equal to 45 percent, the effective active substance is more than or equal to 53.5 percent, and the insoluble substance is less than or equal to 0.5 percent;
(2) and (3) heating: after the ball is filled, the rotary spherical digester is covered, idled for 15min and then heated; the goal of the rotary motion of the rotary spherical digester is to further mix the poplar slices in the rotary spherical digester with alkali liquor and cooking aids; the temperature rise is one-time temperature rise, and small steam is released once in the middle of the temperature rise process, so that the temperature rise of the poplar pulp is facilitated; controlling the temperature rise time to be 62min, and uniformly and slowly raising the temperature to 170 ℃;
the temperature rise time is prolonged and the temperature rise is slow, so that the uniformity of wood chip cooking can be better ensured, the severe oxidation of cellulose caused by severe temperature rise is reduced, and the bulk and tensile index of the prepared natural color poplar pulp are further improved; the small steam release time is 10 min; the pressure after small steam release is 0.4 MPa; the temperature is reduced to 150 ℃ after small steam release;
(3) and (3) heat preservation: after the temperature is increased, the boiling pressure is stabilized between 0.75MPa, the spherical digester is subjected to heat preservation for 55min, the pulp testing is started by using a pulp testing valve after the heat preservation is carried out for 40min, and the steam is greatly released after the hardness of the pulp testing is 18K; when the large air is released until the pressure is 0, black liquor is injected into the ball; the temperature in the ball is rapidly reduced, the ball cover is convenient to open, and meanwhile, the pollution and the water waste are reduced; the amount of black liquor injected into the steaming ball is 8 square/ball, and the ball cover is opened to pour the material after cooling.
(4) Washing the pulp: after the pulp in the ball is poured into the ball lower tank, the concentration of the pulp is diluted to about 3% by using circulating black liquor, the pulp is beaten to a skip sieve by using a pulp pump to sieve out impurities such as wood knots, and the sieved pulp is washed by a front horizontal belt type pulp washer and a rear horizontal belt type pulp washer respectively; controlling the residual alkali of the washed slurry to be below 0.2 g/l; extracting black liquor, washing, and recycling alkali from a part of extracted black liquor; a part of black liquor system is internally circulated with slurry dilution and spherical digester cooling; and pulping after the pulp washing is finished, wherein the pulping degree is 25 degrees SR.
(5) Removing impurities: removing impurities from the pulp by a pressure screen, sending the good pulp to a second-stage slag remover for removing slag, and diluting and washing the pulp in a pulp tank after the slag is removed by a rotary screen thickener; the concentration of the diluted slurry is 4 percent, and the diluted slurry is sent to a pulp machine for papermaking; the pressure of the pressure screen is 0.13 MPa; the concentration of the slurry concentrated by the cylinder thickener is 10 percent.
(6) Manufacturing paper: the paper making process comprises the working procedures of a pulp storage tank, a net part, a pressing part, a drying part, a paper cutting and arranging machine and weighing and packaging; the pulp concentration of the pulp storage tank is 2.5 percent; the concentration of the pulp on the net part is 1.5 percent, and the dryness of the pulp on the net part is more than 20 percent; the press section comprises a first press area, a second press area and a third press area; the first nip pressure was 3.5kg and the second nip pressure was 5.5 kg; the pressure in the triple nip was 5.8 kg; the dryness of the pulp sheet in the third area is more than 58 percent; the air pressure of the drying part entering a drying cylinder is 0.3 MPa; the water content of the pulp pages at the drying part is 10%, and the quantitative rate is 800g per square meter.
Example 3 production Process of unbleached poplar pulp
The method comprises the following steps:
(1) and (3) cooking: conveying the poplar slices to a screw conveyor through a towing belt, and adding prepared alkali liquor and a cooking auxiliary agent into the middle section of the screw conveyor; after the poplar slices are uniformly mixed with alkali liquor and a cooking aid in a screw conveyor, putting the mixed poplar slices into a rotary spherical digester through a spherical digester, and cooking;
the poplar chips meet the following indexes: 23 percent of water, 1.0-1.4mm of thickness, no impurities, no bark and no black rot; adding the alkali liquor into a screw conveyor at the temperature of 100 ℃; the ball throwing amount (air drying) of the poplar chips in the rotary spherical digester is 8.5 t/ball; the amount of alkali used for cooking is 20 percent; the ratio of the cooking liquor is 1: 2;
the dosage of the cooking auxiliary agent is 8.0 kg/ball; the novel anthraquinone cooking agent is preferably produced by Henan Honorede new material science and technology company; the novel anthraquinone has the fineness of 100 meshes, the water content is less than or equal to 0.2%, the free quinone is more than or equal to 45%, the effective active substance is more than or equal to 53.5%, and the insoluble substance is less than or equal to 0.5%.
(2) And (3) heating: after the ball is filled, the rotary spherical digester is sealed and idled for 20 min; then heating is carried out; the goal of the rotary motion of the rotary spherical digester is to further mix the poplar slices in the rotary spherical digester with alkali liquor and cooking aids; the temperature rise is one-time temperature rise, and small steam is released once in the middle of the temperature rise process, so that the temperature rise of the poplar pulp is facilitated;
controlling the temperature rise time to be 58min, and uniformly and slowly raising the temperature to 165 ℃; the temperature rise time is prolonged and the temperature rise is slow, so that the uniformity of wood chip cooking can be better ensured, the severe oxidation of cellulose caused by severe temperature rise is reduced, and the bulk and tensile index of the prepared natural color poplar pulp are further improved;
the small steam release time is 8 min; the pressure after small steam release is 0.6 MPa; the temperature is 150 ℃ after small steam release;
(3) and (3) heat preservation: after the temperature is increased, the boiling pressure is stabilized to about 0.75MPa, the spherical digester is subjected to heat preservation for 58min, the pulp testing is started by using a pulp testing valve after the temperature is preserved for 35min, and the steam is released greatly when the hardness of the pulp testing is in the range of 16-18K;
when the large air is released until the pressure is 0, black liquor is injected into the ball; the temperature in the ball is rapidly reduced, the ball cover is convenient to open, and meanwhile, the pollution and the water waste are reduced; the amount of black liquor injected into the steaming ball is 6 square, and the ball cover is opened to pour the material after cooling.
(4) Washing the pulp: after the pulp in the ball is poured into the ball lower tank, the concentration of the pulp is diluted to about 3% by using circulating black liquor, the pulp is beaten to a skip sieve by using a pulp pump to sieve out impurities such as wood knots, and the sieved pulp is washed by a front horizontal belt type pulp washer and a rear horizontal belt type pulp washer respectively; controlling the residual alkali of the washed slurry to be below 0.2 g/l; after washing and extracting black liquor, sending a part of extracted black liquor to alkali recovery; a part of black liquor system is internally circulated with slurry dilution and spherical digester cooling; and pulping after the pulp washing is finished, wherein the pulping degree is 25 degrees SR.
(5) Removing impurities: removing impurities from the pulp by a pressure screen, sending the good pulp to a second-stage three-section slag remover for removing slag, and diluting and washing the pulp in a pulp tank after the slag is removed by a rotary screen thickener; the concentration of the diluted slurry is 2-4%, and the diluted slurry is sent to a pulp machine for papermaking; the pressure of the pressure screen is 0.15 MPa; the concentration of the slurry concentrated by the cylinder thickener is 12 percent.
(6) Manufacturing paper:
the paper making process comprises the working procedures of a pulp storage tank, a net part, a pressing part, a drying part, a paper cutting and arranging machine and weighing and packaging; the pulp concentration of the pulp storage tank is 2.5 percent; the concentration of the pulp on the net part is 1.5 percent, and the dryness of the pulp on the net part is more than 20 percent; the press section comprises a first press area, a second press area and a third press area; the first nip pressure is 4.5kg and the second nip pressure is 4.5 kg; the triple nip pressure was 5.5 kg; the dryness of the pulp sheet in the third area is more than 58 percent;
the air pressure of the drying part entering a drying cylinder is less than or equal to 0.4 MPa;
the water content of the pulp sheets discharged from the drying part is 11.5%, and the quantitative rate is 650g per square meter.
The following are relevant indexes of the natural colored poplar pulp prepared in the embodiments 1, 2 and 3 of the invention, and specific detection indexes are shown in table 1:
TABLE 1
As can be seen from the above table, the natural color poplar pulp prepared by the method has moderate whiteness, meets the aesthetic requirements of modern people, has higher tensile index, particularly reaches 95.28 n.m/g, has lower tearing index and is more suitable for being used as household paper.
In the invention, the inventor finds that the temperature rise time, the temperature rise temperature and the amount of the cooking aid have important influence on the indexes of the natural-color poplar pulp prepared by the invention, and adopts the method of the embodiment 3 to detect each index of the prepared natural-color poplar pulp under the condition of changing the temperature rise time, the temperature rise temperature and the amount of the cooking aid so as to find out the optimal production process, which is specifically shown in table 2
TABLE 2
As can be seen from the above table, when the temperature rise time is 58min, the temperature rise temperature is 165 ℃, and the consumption of the cooking aid is 8.0 in the implementation process of the invention, the natural color poplar pulp prepared by the invention has the bulk of 1.95 cm3G, tensile index of 95.28 N.m/g, tear index of 5.40Mn.m2And g, when the temperature rise is above 175 ℃ and the consumption of the cooking aid is above 8kg and below 7kg, all indexes of the prepared natural-color poplar pulp are greatly reduced, and the optimal process combination of the invention is that the temperature rise time is more than or equal to 50 ℃, the temperature rise temperature is 165-175 ℃ and the consumption of the cooking aid is 7-8 kg/ball.
In the invention, the volume of the rotary spherical digester is 40 square; it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still make modifications to the technical solutions described in the foregoing embodiments, and any modifications, equivalent substitutions, improvements, etc. within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (3)
1. An unbleached poplar pulp characterized by: the whiteness of the natural color poplar pulp is 28-30%, the bulk is 1.60-1.95 cm3/g, and the hardness is 15-25K;
the preparation process of the natural color poplar pulp comprises a cooking step; the cooking step comprises: conveying the poplar slices to a screw conveyor, and adding prepared alkali liquor and a cooking auxiliary agent into the screw conveyor; mixing poplar slices with alkali liquor and a cooking aid in a screw conveyor, and putting the mixed material into a rotary spherical digester for cooking; the temperature of the alkali liquor added into the screw conveyor is 80-100 ℃; the ball throwing amount of the poplar chips in the rotary spherical digester is 8.5-9.0 t/ball; the dosage of the cooking auxiliary agent is 7-8 kg/ball; the cooking agent is anthraquinone, the fineness of the anthraquinone is 100 meshes, the water content is less than or equal to 0.2%, the free quinone is more than or equal to 45%, the effective active substance is more than or equal to 53.5%, and the insoluble substance is less than or equal to 0.5%;
the preparation process of the natural color poplar pulp also comprises a temperature rise step; in the temperature rising step, after the spherical digester is filled, the spherical digester is rotated for 5-20 min after being covered by a cover; controlling the temperature rise time to be more than 50min, and slowly raising the temperature in the rotary spherical digester to 165-175 ℃; small steam release is carried out in the middle of the temperature rising process; the small steam release time is 5-10 min; the pressure of the small steam-released rotary spherical digester is 0.3-0.6 MPa; the temperature of the small steam-released rotary spherical digester is 140-160 ℃;
the preparation process of the natural color poplar pulp further comprises a heat preservation step, wherein the heat preservation step comprises big air release; when the pressure of the steam ball is 0 in the large air release step, black liquor is injected into the steam ball; the amount of the black liquor injected into the steaming ball is 3-8 square/ball;
the preparation process of the natural color poplar pulp further comprises a papermaking step, wherein the papermaking step comprises the working procedures of a pulp storage tank, a net part, a pressing part, a drying part, a paper cutting and arranging machine and weighing and packaging; the pulp concentration of the pulp storage tank is 2.5-3%; the concentration of the pulp on the net part is 1.2-1.5%, and the dryness of the pulp on the net part is more than 20%; the press section comprises a first press area, a second press area and a third press area; the pressure of the first pressing area is 3.5-4.5 kg, and the pressure of the second pressing area is 4.5-5.5 kg; the pressure of the three-pressure area is 5.5-6.5 kg; the dryness of the pulp sheet discharged from the three-pressure area is more than 58 percent; the air pressure of the drying part entering a drying cylinder is less than or equal to 0.4 MPa; the water content of the pulp pages at the drying part is 10 +/-1.5%, and the quantitative rate is 700 +/-100 g per square meter.
2. The greige poplar pulp of claim 1, wherein: the natural color poplar pulp has the following indexes met by the preparation raw material poplar chips: the water content is less than or equal to 25 percent, and the thickness is 0.8-1.8 mm.
3. The greige poplar pulp of claim 1, wherein: the preparation process of the natural-color poplar pulp further comprises the pulp washing step: pouring the cooked pulp into a ball discharging pool, diluting the pulp to 3% by using circulating black liquor, screening impurities out of the pulp, and washing the pulp after screening by using a pulp washer; controlling the residual alkali of the washed slurry to be below 0.2 g/l; and (3) sending part of black liquor obtained after the pulp is washed to alkali recovery, and sending part of black liquor to a system for circularly diluting the pulp and cooling the rotary spherical digester.
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