CN110700004A - Preparation method of natural-color bamboo fiber biochemical mechanical pulp - Google Patents

Abstract

The invention belongs to the field of pulping and papermaking, in particular to a preparation method of natural bamboo fiber biochemical mechanical pulp. The method comprises the following steps: 1) preparing materials by dry method; 2) sending the bamboo chips obtained in step 1) into a press for pressing; 3) feeding animal excrement, bamboo chips, and screened bamboo chips, bamboo pith and knots, etc. Finely crushed sundries are mixed in proportion and then composted by aerobic fermentation, and high-efficiency active biological compound bacteria are added at the same time; 4) Screening and dust removal treatment is carried out after fermentation; 5) The bamboo chips after screening and dust removal are washed away by a washing machine surface material and remove excess water; 6) lye pre-impregnation; 7) refining or beating; 8) papermaking. The method combines biological, chemical and physical methods to produce natural bamboo fiber chemical mechanical pulp for packaging, and at the same time makes full use of the leftover materials in the production process, turns waste into treasure, and realizes the full and high quality of bamboo raw materials. use.

Description

A kind of preparation method of natural bamboo fiber biochemical mechanical pulp

technical field

The invention belongs to the field of pulping and papermaking, and in particular relates to a method for preparing a high-density pulp by using bamboo as a raw material by cutting off raw materials, pre-pressing, mixing and fermenting, screening and dedusting, washing, lye pre-impregnation, high-consistency beating, low-consistency beating, and papermaking. Natural bamboo fiber biochemical mechanical pulp with added value, less environmental pollution and better quality for packaging; natural bamboo fiber biochemical mechanical pulp can also be used to make natural paper and other products. Specifically, it is a preparation method of natural bamboo fiber biochemical mechanical pulp.

Background technique

In recent years, my country's paper industry has been in the transition period of reducing production capacity and adjusting structure. Compared with other packaging materials, packaging paper and cardboard, as the main packaging materials, are sustainable, excellent in foldability, good elasticity, light in weight, and good in quality. Printing performance, good transport performance, and the characteristics of hygienic, non-toxic, odorless, recyclable, environmentally friendly, and cost-effective. With the rapid growth of e-commerce, the prosperity of the packaging paper and cardboard industry continues to rise.

From the perspective of the structure of paper products and the proportion of consumption, packaging paper has an important position in the entire paper and cardboard products. At present, the production of paper and cardboard used for packaging in my country accounts for about 59% of the total production, and the consumption accounts for about 61% of the total consumption. With the continuous development of the domestic packaging industry, paper packaging products will occupy more packaging industry markets, and packaging paper and cardboard will also occupy a larger share in the paper industry.

my country is a country with a serious shortage of forest resources, protect forests, maintain ecological balance, and prohibit deforestation. It is reported that the total amount of domestic waste and imported waste paper fibers usually accounts for more than 90% of the fiber raw materials required for the production of packaging paper and cardboard in China. This data shows that my country's packaging paper and cardboard production is very dependent on waste paper raw materials. However, reducing the type of imported waste paper and the amount of imported waste paper will lead to a substantial reduction in the amount of imported waste paper in my country, which will make the vast majority of enterprises that use waste paper to produce packaging paper and cardboard generally face a shortage of imported raw materials and a huge market gap. , so that waste paper is in short supply situation, resulting in domestic waste paper becoming a "sought-after". The limited import of waste paper has led to a shortage of fiber raw material supply for packaging paper and cardboard. In addition, the demand for fiber raw materials will increase due to the addition of new production capacity in the future. Therefore, the problem of raw materials will be a huge challenge for Chinese packaging paper and cardboard manufacturers.

To sum up, the current raw materials for the production of packaging paper and cardboard are mainly waste paper fibers and a small amount of wood fibers. There are few reports at home and abroad on the use of bamboo fibers to produce packaging paper and cardboard, and there are very few studies. necessity of this invention.

China is located in the center of the world's bamboo distribution, and the bamboo plant resources are very rich. The national bamboo forest area is about ⁵ million hectares, accounting for 20%-25% of the world's total bamboo forest area, so it has the reputation of "Bamboo Kingdom". Bamboo plants have the characteristics of fast growth, strong adaptability, short cutting period, high yield, biodegradation, one-time cultivation, multiple harvesting, and good antibacterial and bacteriostatic properties. It plays a very important role in China's forestry industry and has become one of the four sunrise industries in my country's forestry. Analysis results of chemical composition and fiber morphology of bamboo raw materials: cellulose content 40%-52% (coniferous wood 40%-55%), fiber length 1.5-3.5mm (coniferous wood 3-5mm), aspect ratio 100-200 (Coniferous wood is about 60-110), the fiber shape and content of bamboo are similar to the high-quality raw material of pulp and paper-coniferous wood, so bamboo is also one of the excellent pulp and paper raw materials.

Studies have shown that bamboo contains more lignin (content about 23-33%), pentose hemicellulose (content about 17-25%), organic solvent extract (content about 2.0-9.0%), ash (content about 2.0-9.0%) About 1.2-3.5%) and heterocells (about 20-31%) and other non-cellulose impurities, and the structure is tight and firm (the density of bamboo wood is 0.52-0.68g/cm ³ , and the bamboo leaf wood is about 0.4g/cm ³ ). , the hardwood is 0.43-0.64g/cm ³ ).

SUMMARY OF THE INVENTION

The purpose of the present invention is to aim at, and provide a kind of preparation method of natural bamboo fiber biochemical mechanical pulp. The method can solve the raw material bottleneck problem faced by the existing packaging paper and cardboard manufacturers in my country, and fully utilize the high-yield and high-quality bamboo as raw materials, and combine biological, chemical and physical methods to produce natural bamboo fiber chemical mechanical pulp for packaging. At the same time, it makes full use of the leftover materials in the production process (that is, bamboo scraps, pith, knots and other sundries), turns waste into treasure, and realizes the full and high-quality utilization of bamboo raw materials. On the one hand, the surface of the bamboo chips is more porous, and the material is softened, which alleviates the problems of uniformity and quality instability in the cooking due to the tight and firm structure of the bamboo, which is difficult to penetrate and difficult to control. Manure and other animal manures become bio-organic fertilizers with more comprehensive nutrition.

In order to achieve the above object, the present invention adopts the following technical solutions:

A method for preparing natural bamboo fiber biochemical-mechanical pulp, firstly, pre-pressing qualified bamboo chips to make the bamboo chips produce fine cracks in the longitudinal direction, which is conducive to the uniform penetration of the subsequent medicinal liquid, improves the cooking uniformity, and reduces the problem of bamboo damage from the source. The structure is compact, which makes it difficult to control the uniformity and quality of cooking, as well as the weakness of bamboo that contains a lot of non-cellulose impurities. After fermentation, screening and dust removal, the material softens, which is beneficial to the subsequent cooking liquid. Penetration can improve the cooking uniformity and cooking efficiency, and can also reduce the cooking dosage, thereby reducing the decrease in pulp yield and quality caused by the increased alkaline degradation caused by the increase in the dosage. Refining can separate more complete fibers, reduce the generation of debris, improve the strength of the pulp after grinding, and help ensure the quality and output of the uncolored pulp board.

The preparation method specifically includes the following steps:

(1) Material preparation: The material preparation adopts the dry method, that is, the bamboo is cut into bamboo pieces with a length of 10-50mm and a width of 5-20mm. The size of the product, the pass rate is more than 85%. The screened bamboo chips, bamboo pith, knots and other fine debris are used for fermentation.

(2) Pre-pressing: the bamboo chips obtained in step (1) are sent into the press for pre-pressing, the pre-pressing pressure is 2.5-5.0MPa, the pressing time is 2-10min, and the temperature is normal temperature.

The purpose of pre-pressing: Using the mechanical extrusion action of the press, the bamboo chips can be made to produce small cracks in the longitudinal direction, which is conducive to the uniform penetration of the subsequent liquid medicine, improves the cooking uniformity, and reduces the bamboo wood from the source. Due to the tight structure, the penetration is difficult and it is difficult to control the cooking. Uniformity, quality instability and other problems; pre-pressing can also flatten and crush the protrusions of the bamboo joints, and then through subsequent fermentation, screening and dust removal, the crushed bamboo dust, bamboo knots, bamboo pith, and bamboo can be effectively removed. The impurities on the surface of the sheet can effectively overcome the weakness of bamboo that contains many non-cellulose impurities from the source.

The press adopts double-roll press, the upper and lower double-rolls are steel-clad rolls, and both upper and lower rolls have smooth and smooth surfaces. The press used in this patent belongs to the equipment in the pressing device of the paper machine. The press is widely used in the pressing and dewatering of wet paper sheets and belongs to the prior art, so its specific structure will not be repeated.

(3) Bamboo chip fermentation: add water to wet the pre-pressed bamboo chips to make the water content 45%-55%; Animal excrement such as feces and the bamboo chips moistened with water, together with the fine debris such as bamboo chips, bamboo pith, and knots in step (1), are mixed and stirred evenly in proportion. -2m, a long strip with a height of 0.8-1m, covered with sacks or straw curtains for aerobic fermentation and composting. While mixing, high-efficiency active biological compound bacteria such as yeast, lactic acid bacteria, rhizopus and enzymes are added. Relative to the quality of dry bamboo chips, the dosage of high-efficiency and active biological compound bacteria is 2-5%. Animal manure such as cow dung, sheep dung, horse dung, pig dung, etc. with a water content of 20%-40%, and the bamboo chips after adding water to moisten, and the finely broken sundries such as bamboo chips, bamboo pith, and knots in step (1) The mass ratio of the mass summation is 5-3:5-7; wherein the mass ratio of the bamboo chips after adding water and the fine debris such as bamboo chips, bamboo pith, knots in the step (1) is 8-9:1 -2.

To further optimize the plan, the above-mentioned high-efficiency active biological compound bacteria is composed of the following raw materials by weight percentage: yeast 15%, lactic acid bacteria 15%, rhizopus 10%, protease 10%, lipase 15%, saccharification enzyme 15%, 10% of xylanase, 10% of pectinase, and the total mass percentage of high-efficiency active biological compound bacteria is 100%.

Cow dung, sheep dung, horse dung, pig dung and other animal dung are mixed and fermented with bamboo chips and prepared fine debris. Bamboo chips and prepared materials contain more sugar, water, and organic matter such as protein and fat, which are good for bacteria. Fermentation provides the required nutrients, which is conducive to the rapid reproduction of microorganisms. At the same time, it is accompanied by a series of complex biochemical reactions. The reactions will produce a large number of special green metabolites, such as enzymes, antibiotics, hormones and other substances, and in the composting process. Since the fermentation of cow dung, sheep dung, horse dung, pig dung and other animal dung releases heat, it further promotes the reproduction and biochemical reaction of microorganisms, which accelerates the microbial degradation of bamboo chips, which is beneficial to the biodegradation of low-cluster substances in bamboo chips. The interlayer and cell wall tissue are damaged to varying degrees, the surface of the bamboo sheet is more porous, and the material is softened, which is conducive to the penetration of the subsequent cooking liquid, improves the cooking uniformity and cooking efficiency, and can also reduce the amount of cooking drugs, thereby reducing the amount of drugs due to drug use. The increase in the amount leads to aggravated alkaline degradation and a decrease in pulping yield and quality. At the same time, the softening of the bamboo sheet material is beneficial to the subsequent pulp refining, which can separate more complete fibers, reduce the generation of debris, improve the strength of the pulp after grinding, and help ensure the quality and output of the uncolored pulp board.

The color of animal manure changes from black to yellow after fermentation, and it emits the smell of alcohol, becoming a bio-organic fertilizer with more comprehensive nutrition. The large and rapid reproduction of the above-mentioned microorganisms is accompanied by a series of complex biochemical reactions, and the reactions will produce a large number of special green metabolites, such as enzymes, antibiotics, hormones and other substances. These substances are naturally produced by the organism itself, not Foreign chemical antibiotics and hormones are beneficial and harmless. Among them, antibiotics can significantly inhibit the spread of soil-borne pathogens and improve the disease resistance and stress resistance of crops; while hormones can stimulate the rapid growth and development of crops.

The stacking time is 72-120h, and the moisture content of the bamboo chips after fermentation is 14-22%.

(4) Screening and dedusting: Screening and dedusting treatment is carried out after the fermentation, so that the fermented bamboo chips of qualified size are separated from the fermented animal dung, such as cow dung, sheep dung, horse dung, and pig dung, as well as the prepared fine debris.

Preferably, the screening and dust removal equipment adopts a high-frequency vibrating flat screen. Screening is to use the different geometric size and shape of bamboo chips and fermented animal feces, and use a sieve plate with holes or slits to make the fermented animal feces pass through the sieve plate under a certain pressure, and the bamboo chips are trapped in the sieve plate. The fermented bamboo chips are separated from the fermented cow dung, sheep dung, horse dung, pig dung and other animal manures.

High-frequency vibrating flat screen is widely used in pulp screening. The screening principle is that under the action of the pressure difference on both sides of the screen plate and the vibration of the screen plate, the fibers pass through the screen holes, and the impurities with large geometric size are trapped in the inlet. pulp side. The high-frequency vibrating flat screen belongs to the prior art, so its specific structure will not be repeated.

The separated fermented cow dung, sheep dung, horse dung, pig dung and other animal dung and prepared fine debris have an organic matter content of more than 50%, and then matched with different nutrient elements to form vegetables, flowers and fruit trees. , grain, cotton, oil and other series of special fertilizers for crops.

The residence time of the fermented bamboo chips in the high-frequency vibrating flat screen is 20-40min.

(5) washing section: the bamboo chips after screening and dedusting in step (4) are washed with a washing machine to remove substances such as animal feces on the surface and remove excess water. After washing and dehydration, the moisture content of bamboo chips is 30%-45%.

The washing machine adopts a hydraulic disintegrator. Processing conditions: bamboo chips 20-40min. The ratio of the quality of the absolutely dry bamboo chips in the washing machine to the total liquid amount in the washing machine (the quality of the absolutely dry bamboo chips + the quality of the liquid) is 3-6%.

The hydraulic pulverizer is widely used in the wet preparation of grass raw materials. Its shape is spherical, and the bottom is equipped with an impeller and a sieve plate. After the materials are scattered and washed out, they are discharged through the sieve holes on the sieve plate of the disintegrator. Both the hydraulic disintegrator and the screw dehydrator belong to the prior art, so their specific structures will not be repeated.

(6) lye pre-impregnation: the washed bamboo chips are sent into the cooking vessel, and alkaline substances are added to carry out lye pre-impregnation. Relative to the dry raw material quality, the amount of alkaline substances in the lye pre-impregnation is 3-7%, the time is 40-120min, the temperature is 80-100℃, the liquid ratio is 1:3-6, and the pressure is 0.15-0.3MPa (nitrogen pressure). ). The alkaline substances mentioned here refer to sodium hydroxide and/or potassium hydroxide and/or sodium sulfite. The liquid ratio refers to the ratio of the mass g of absolutely dry bamboo chips in the cooking container to the total volume ml of liquid in the cooking container.

The purpose of pre-impregnation of lye is to increase the boiling point of cooking liquid, prevent or reduce the interface between liquid-solid two-phase (ie solution and fiber raw material) and hinder sodium hydroxide and/or potassium hydroxide and/or sodium sulfite The generation of vapor bubbles in the osmotic transfer of the solution can maintain the transfer coefficient at a high level. On the other hand, increasing the pressure can improve the mass transfer process of sodium hydroxide and/or potassium hydroxide and/or sodium sulfite from the solution into the fiber raw material , which is beneficial for the effective degradation of sodium hydroxide and/or potassium hydroxide to occur more inside the fiber, which is more conducive to improving sodium hydroxide and/or potassium hydroxide to remove alkali-soluble inorganic and organic substances in bamboo chips, Increasing the number of voids on the cell wall is conducive to the irreversible and permanent softening of the bamboo chips, which lays the foundation for the subsequent refining to separate complete fibers, increase the long fiber components, and reduce fiber cutting. Pulp energy consumption, improve pulp strength, and the chemical inertness of nitrogen can protect raw fibers from excessive alkali oxidative degradation, thereby ensuring pulp yield and quality after cooking.

(7) Refining (or beating): refining the slurry obtained after pre-impregnation with lye in step (6).

The impregnated bamboo fibers are refined in two stages, the first stage is refined with medium or high consistency, and the second stage is refined with low consistency. The beating concentration below 10% is called low-consistency refining, the beating concentration of 10-20% is called medium-consistency refining, and the beating concentration above 20% is called high-consistency refining. The purpose of combining medium or high-consistency refining with low-consistency refining is: during medium or high-consistency beating, fibers are prone to twist and entanglement, and once the discharge is cooled, it will be fixed and affect the strength development of pulp paper. Therefore, low-consistency beating is used after medium or high-consistency beating. On the one hand, the fibers can be further divided, brushed, and homogenized without being cut off. On the other hand, medium or high-consistency beating can be produced by low-consistency beating. The twisted and entangled fibers are re-stretched, thereby stabilizing the pulp quality and meeting the quality requirements of packaging paper for the physical strength of the finished paper. After the two-stage beating is completed, the beating degree of bamboo fiber pulp is 26-36°SR.

Beating equipment: Medium or high consistency disc refiner is used for medium or high consistency beating. Medium or high consistency beating is especially suitable for medium and short fiber pulp. The main purpose of using medium or high consistency beating is to improve the beating quality and reduce the energy consumption of beating. effect, friction generates heat, the fiber absorbs heat and becomes soft and plastic, reducing the cutting effect of the tooth edge on the fiber, and increasing the fine fiberization of the fiber; the reduction of beating energy consumption is mainly due to the friction between the fibers during medium and high consistency beating The effect is increased, and the possibility of contact and friction between the grinding discs is reduced, thereby reducing the energy consumption of beating.

To further optimize the plan, in addition to the medium or high consistency disc mill, the twin-screw extrusion thread rolling machine can also be used for medium or high consistency beating. The twin-screw extrusion thread rolling machine adopts a knifeless refining element, and uses the dynamic extrusion principle. When grinding the slurry, the two parallel and intermeshing screws force the slurry like a high-efficiency screw pump. The slurry is extruded and transported along the fiber axis directionally, and the pulp is subjected to a large extrusion force and rubbing action in the fiber axis direction in the crushing area, which is conducive to the generation of cracks in the fiber axis, and strengthens the liquid penetration and fiber separation. , complete the refining function. The extrusion rolling time is 20-60min, the temperature is room temperature, the inlet pulp is 18-30% thick, and the outlet pulp is 35-55% thick.

The twin-screw extrusion thread rolling machine used in this application is a twin-screw extruder used in the plastics and food industries. . The energy-saving clean mechanical pulping equipment belongs to the prior art, so its specific structure will not be repeated.

A cylindrical refiner is used for low-consistency beating. The application uses a cylindrical refiner for low-consistency beating, and the blades of the knife roll and stator use stone knives. The main reason is that the material of the blade has a great influence on the beating efficiency and pulp quality of the equipment. The diameter of the fiber is larger, the total length of the pores and the total area of the pores in the unit area are larger, so the fiber splitting and brooming effect is larger, the water retention performance of the fiber is improved, and the cutting damage effect is not large, so as to ensure the quality of the finished paper. Yield. Because the direction of centrifugal force is 90° from the direction of the slurry flow, the cylindrical refiner completely separates the refining process from the pumping of the slurry, and makes the flow rate of the slurry on the entire cylindrical surface consistent with the linear speed of the knife, that is to say, the refining conditions Consistent, with the same effective edge load (SEL) throughout the process, the results of the seminal pulp are easier to control. Due to the action of centrifugal force, during the time period from when the pulp enters the refining zone to the time it leaves the refining zone, the water is removed from the pulp and thrown into the groove of the outer stator knife, and the concentrated pulp layer is just in the refining zone. The surface of the zone can make more energy act on the fiber, and achieve the purpose of fine fiberization with less energy consumption.

For the above-mentioned bamboo fiber pulp beating temperature: medium or high-consistency beating temperature is room temperature, low-consistency beating temperature is 30-50 ℃; beating time: medium or high-consistency beating time is 80-120min, and low-consistency beating time is 40-60min.

(8) Papermaking: The natural bamboo fiber pulp after refining in (7) is subjected to pulp board papermaking, using a board machine that is well known to papermakers. The cardboard machine used in this solution belongs to the papermaking equipment of the paper machine and belongs to the prior art, so its specific structure will not be repeated.

The physical properties of the natural bamboo fiber biochemical-mechanical pulp prepared by the above method are as follows: the yield is 65-75%, the average fiber length is 1.3-1.9mm, the average fiber width is 15.0-22.5μm, and the tightness is 0.68-0.75g/ m ³ , the longitudinal fracture length is 2.86-3.79km, the transverse compressive strength index is 5.4-7.1N·m/g, the longitudinal tear index is 9.71-11.36mN·m ² /g, and the burst resistance index is 2.83-3.21kPa·m ² /g, whiteness 18.2-38.5% ISO, basis weight 80-130 g/m ² . Among them, the yield is the pulp yield before the two-stage beating after lye pre-impregnation, for absolutely dry raw materials (same as above); the other performance indicators are the pulp performance indicators after two-stage beating (same as above).

In addition to using bamboo as the raw material, the above method can also be non-wood plant fiber raw materials such as corn stalk, sorghum stalk, rice straw, pennisetum, imperial bamboo grass and honeysuckle grass.

Compared with the prior art, the beneficial effects of the present invention are:

(1) The present invention utilizes my country's high-quality and low-cost bamboo to replace waste paper or wood to produce high value-added biomass fiber material for natural environmental protection paper-based packaging, and develops a production process for natural environmental protection paper-based packaging biomass material, which makes the natural color A new sustainable and renewable raw material has been added to the production field of biomass materials for environmentally friendly paper-based packaging, and the production cost has been greatly reduced, making the product more economical, better meeting the needs of price-sensitive consumers, and reducing The cost pressure of raw materials in my country's related industries.

(2) The present invention does not use harmful chemical reagents such as bleaching agents and fluorescent powders, and eliminates persistent organic pollutants (such as chloroform, chlorinated phenolic compounds, chlorinated dioxins, etc.) that endanger the environment and the health of living organisms from the source. The production of toxic chlorinated organic compounds such as cyanobacteria and furans) maintains the pure and natural essential characteristics of the product, and meets the ecological, health and environmental protection requirements of modern people, so as to realize the sustainable development and production of natural bamboo fiber biochemical mechanical pulp. Environmental protection is coordinated.

(3) The present invention makes the surface of the bamboo slices more porous on the one hand, softens the material, and alleviates the problems of uniformity and quality instability due to the tightness and firmness of the bamboo wood tissue structure, and the difficulty in soaking and controlling the cooking; Softening is beneficial to the subsequent pulp refining, which can separate more complete fibers, reduce the generation of debris, and improve the strength of the pulp after grinding; Nutritionally comprehensive bio-organic fertilizer.

(4) The present invention prepares high added value, less environmental pollution and better quality by cutting off materials, pre-pressing, mixing and fermenting, screening and dedusting, washing, lye pre-impregnation, high-consistency beating, low-consistency beating, and papermaking. The natural bamboo fiber pulp used for packaging can not only improve the profits of enterprises, but also promote the development of the bamboo industry, adjust the agricultural industry structure, broaden the channels for farmers to increase income, and drive the poor people to participate in bamboo planting, so as to achieve precise poverty alleviation and sustained and stable income increase to become rich. The formation of "substituting bamboo for wood and bamboo for waste (paper)" to make pulp and paper provides a new way for the development of benign interaction between grass, pulp and paper.

(5) The present invention adopts the combination of medium or high-consistency beating and low-consistency beating. On the one hand, the fibers can be further divided, brushed, and homogenized without being cut off as much as possible. On the other hand, by low-consistency beating, Re-stretching of twisted and entangled fibers in medium or high consistency beating ensures pulp quality.

(6) In the present invention, nitrogen is used to pressurize the lye pre-impregnation, and its purpose is to increase the boiling point of the cooking liquid and prevent or reduce the interface between the liquid-solid two phases (ie the solution and the fiber raw material) that hinders the penetration and transfer of the liquid. The generation of steam bubbles can maintain the transfer coefficient at a high level. On the other hand, increasing the pressure can improve the mass transfer process of the liquid medicine into the fiber raw material, which is beneficial to the dissolution of alkali-soluble inorganic and organic substances in bamboo chips. Increasing the number of voids on the cell wall is conducive to irreversible and permanent softening of bamboo chips, laying a foundation for subsequent refining, reducing energy consumption for refining, and improving pulp strength. Oxidative degradation by excessive alkalinity, thus ensuring pulp yield and quality after cooking.

Detailed ways

The present invention will be further described in detail below through examples, but the protection scope of the present invention is not limited to this specific embodiment. The present invention extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

The high-efficiency active biological compound bacteria used in this application is composed of the following raw materials by weight percentage: yeast 15%, lactic acid bacteria 15%, rhizopus 10%, protease 10%, lipase 15%, saccharification enzyme 15%, 10% of xylanase, 10% of pectinase, and the total mass percentage of high-efficiency active biological compound bacteria is 100%.

The % recorded in this application, unless otherwise specified, refers to its mass percentage, that is, wt%.

Embodiment 1:

A preparation method of natural bamboo fiber biochemical mechanical pulp, comprising the following steps:

(1) The dry method is used for material preparation, and the raw bamboo is cut into bamboo pieces of 10-50mm long and 5-20mm wide; Size and size, the pass rate is more than 85%. The screened bamboo chips, bamboo pith, knots and other fine debris are used when the bamboo chips are fermented.

(2) The qualified bamboo chips after screening are sent to the press for pre-pressing, the pre-pressing pressure is 2.5MPa, the pressing time is 10min, and the temperature is normal temperature.

(3) Bamboo chip fermentation: add water to wet the pre-pressed bamboo chips, so that the water content is 45%-55%; the bamboo chips moistened with water and the shavings, pith, knots etc. The sundries are mixed together with animal manure with a water content of 20%-40%, such as cow dung, sheep dung, horse dung, pig dung, etc. in a mass ratio of 5:5, and the mixture is evenly mixed. 1m long strips covered with sacks or straw curtains for aerobic fermentation and composting. When mixing, adding 5% of the mass of the absolutely dry bamboo chips is high-efficiency active biological compound bacteria fermentation, the fermentation time is 72h, and the moisture of the bamboo chips after fermentation is about 22%.

The mass ratio of the bamboo chips moistened with water and the fine debris such as chips, pith, and knots screened out from the preparation material is 9:1.

(4) Screening and dedusting section: Screening and dedusting treatment is carried out after the fermentation, so that the fermented bamboo chips of qualified size are separated from the fermented animal dung, such as cow dung, sheep dung, horse dung, and pig dung, as well as the finely divided debris. The residence time of the fermented bamboo chips in the high-frequency vibrating flat screen is 20 min.

(5) Washing: the bamboo chips screened and dedusted in step (4) are washed with a washing machine to remove substances such as animal feces on the surface and remove excess water. The ratio of the quality of the absolutely dry bamboo chips in the washing machine to the total liquid amount in the washing machine (the quality of the absolutely dry bamboo chips + the liquid mass) is 4%, and the treatment time of the detergent is 35 minutes. After washing and dehydration, the moisture content of bamboo chips is 40%.

(6)) Pre-impregnation with lye: adding an alkaline substance to the washed bamboo chips to perform pre-impregnation in lye, and the alkaline substance is a mixture of sodium hydroxide and sodium sulfite. Relative to the absolute dry raw material quality, the dosage of sodium hydroxide is 2%, and the dosage of sodium sulfite is 1%. The lye pre-dipping time is 120min, the temperature is 80℃, the liquid ratio is 1:3, and the pressure is 0.15MPa (nitrogen pressure);

(7) Refining (or beating): Two-stage beating is used for the impregnated bamboo fiber, the first stage is medium or high-consistency beating, and the second-stage is low-consistency beating.

Beating equipment: Medium or high consistency disc refiner is used for medium or high consistency beating. Medium or high consistency beating is especially suitable for medium and short fiber pulp; cylindrical refiner is used for low consistency beating.

For the bamboo fiber pre-impregnated with lye, medium or high-consistency beating time is 80min, and the temperature is room temperature; low-consistency beating time is 50min, and the temperature is 30℃. After the two-stage beating is completed, the beating degree of bamboo fiber pulp is 26.4°SR.

(8) Papermaking: The natural bamboo fiber pulp after refining in (7) is subjected to pulp board papermaking, using a board machine that is well known to papermakers. Copying belongs to the prior art and will not be described in detail.

The physical performance indexes of the prepared natural bamboo fiber pulp are: yield 75%, average fiber length 1.46mm, average fiber width 22.5μm, tightness 0.68g/m ³ , longitudinal fracture length 2.86km, transverse ring pressure The strength index is 5.4N·m/g, the longitudinal tear index is 9.71mN·m ² /g, the burst resistance index is 2.83kPa·m ² /g, the brightness is 36.4% ISO, and the basis weight is 84.6g/m ² .

Comparative Example 1: Only the bamboo slice fermentation section was cancelled, i.e., step (2) was cancelled, and the rest of the process and process were the same as those in Example 1.

Comparative Example 2: Only the nitrogen pressure in the lye pre-impregnation section was canceled and changed to normal pressure, and the rest of the process and flow were the same as those in Example 1.

Comparative Example 3: The nitrogen pressure in the bamboo chip fermentation section and the lye pre-dipping section was canceled, and it was normal pressure, and the other processes and processes were the same as those in Example 1.

Comparative Example 4: In the fermentation section of bamboo chips, the high-efficiency and active biological compound bacteria are composed of the following raw materials mixed by weight: 15% yeast, 15% lactic acid bacteria, 10% Rhizopus, 10% protease, 15% lipase, 15% of saccharification enzyme, 10% of xylanase, 10% of pectinase, to become highly active biological compound bacteria is composed of the following raw materials by weight: 40% of yeast, 10% of protease, 15% of lipase, 15% of saccharification enzyme, 10% of xylanase, 10% of pectinase; that is, 15% of lactic acid bacteria and 10% of rhizopus are eliminated, and the original 15% of yeast is changed to 40%, and the rest of the processes and processes are the same as those in Example 1 same.

Comparative Example 5: In the fermentation section of bamboo chips, the high-efficiency and active biological compound bacteria is composed of the following raw materials by weight: 15% yeast, 15% lactic acid bacteria, 10% Rhizopus, 10% protease, 15% lipase, 15% of saccharification enzyme, 10% of xylanase, 10% of pectinase, to become high-efficiency active biological compound bacteria is composed of the following raw materials by weight: 15% of yeast, 15% of lactic acid bacteria, 10% of Rhizopus, Protease 10%, lipase 25%, saccharification enzyme 15%, pectinase 10%; that is, 10% of xylanase is canceled, lipase is changed from 15% to 25%, and the rest of the process and flow are the same as in Example 1 same.

Comparative Example 6: The low-consistency beating after the medium or high-consistency beating was canceled, and the remaining processes and processes were the same as those in Example 1.

Example 2:

A preparation method of natural bamboo fiber biochemical mechanical pulp, comprising the following steps:

(1) The dry method is used for preparing the material, and the bamboo is cut into 10-50mm long and 5-20mm wide; after screening, the large pieces screened out are then cut to make it reach the size of 10-50mm long and 5-20mm wide, which is qualified rate of more than 85%. The screened bamboo chips, bamboo pith, knots and other fine debris are used for subsequent fermentation.

(2) After screening, the qualified bamboo chips are sent to the press for pressing, the pre-pressing pressure is 5.0MPa, the pressing time is 2min, and the temperature is normal temperature.

(3) Bamboo chip fermentation: add water to wet the pre-pressed bamboo chips to make their water content 45%-55%; add water and moisten the bamboo chips together with the shavings, pith, knots, etc. The sundries are mixed together with cow dung, sheep dung, horse dung, pig dung and other animal dung according to the mass ratio of 7:3, and the mixture is evenly mixed. Long strips covered with sack flakes for aerobic fermentation and composting. While mixing, 3.5% high-efficiency active biological compound bacteria are added relative to the mass of the absolutely dry bamboo chips for fermentation, the fermentation time is 120h, and the moisture content of the bamboo chips after fermentation is about 14%.

The mass ratio of the bamboo chips moistened with water and the fine debris such as chips, pith, knots, etc. screened out from the preparation material is 8:2.

(4) Screening and dust removal section: the residence time of the fermented bamboo chips in the high-frequency vibration flat screen is 40min.

(5) Washing: the bamboo chips screened and dedusted in step (4) are washed with a washing machine to remove substances such as animal feces on the surface and remove excess water. After washing and dehydration, the moisture content of bamboo chips is 35%.

(6) lye pre-dipping: with the washed bamboo chips, add alkaline substance to carry out lye pre-dipping, with respect to the absolute dry material quality, the potassium hydroxide consumption in the lye pre-dipping is 4%, time 80min, temperature 95 ℃, liquid ratio 1:6, pressure 0.2MPa (nitrogen pressure);

(7) Refining (or beating): two-stage beating is used for the impregnated bamboo fiber, the first stage is medium or high-consistency beating, and the second-stage is low-consistency beating.

For the immersed bamboo fiber, the medium or high consistency beating time is 120min, the temperature is room temperature, and the equipment is a disc refiner; the low consistency beating time is 40min, and the temperature is 50℃. After the two-stage beating is completed, the beating degree of bamboo fiber pulp is 32.8°SR.

(8) Papermaking: The natural bamboo fiber pulp after refining in (7) is subjected to pulp board papermaking, using a board machine that is well known to papermakers. Copying belongs to the prior art and will not be described in detail.

The physical property indexes of the prepared natural bamboo fiber pulp are: yield 64.8%, average fiber length 1.83mm, average fiber width 17.5μm, tightness 0.71g/m ³ , longitudinal fracture length 3.24km, transverse ring pressure Strength index 6.04N·m/g, longitudinal tear index 10.82mN·m ² /g, burst index 3.01kPa·m ² /g, whiteness 18.2%ISO, basis weight 100.2g/m ² .

Example 3:

A preparation method of natural bamboo fiber biochemical mechanical pulp, comprising the following steps:

(1) Cut the bamboo into 10-50mm long and 5-20mm wide. After screening, the qualified bamboo chips are sent to the press for pressing. The pre-pressing pressure is 3.5MPa, the pressing time is 6min, and the temperature is normal temperature.

(2) Bamboo chip fermentation: The pre-pressed bamboo chips, together with the fine debris such as shavings, pith, knots, etc. screened out from the preparation, are mixed with animal dung such as cow dung, sheep dung, horse dung, and pig dung in a ratio of 6:4 Stir evenly, and after mixing evenly, stack the strips with a length of 2-2.5m, a width of 1.5-2m and a height of 0.8-1m, which are covered with sacks for aerobic fermentation and composting. While mixing, 2% high-efficiency active biological compound bacteria are added relative to the mass of the absolutely dry bamboo chips for fermentation, the fermentation time is 96h, and the moisture content of the fermented bamboo chips is about 17%.

(3) Screening and dust removal section: the residence time of the fermented bamboo chips in the high-frequency vibration flat screen is 20min.

(4) lye pre-impregnation: the bamboo chips after being screened for dust removal and washing are added with alkaline substances to carry out lye pre-impregnation, relative to the absolute dry material quality, the amount of sodium hydroxide in the pre-impregnation is 7%, time 40min, temperature 100℃, liquid ratio 1:5, pressure 0.3MPa (nitrogen pressure);

(5) Refining (or beating): the impregnated bamboo fibers are beaten in two stages, the first stage is refined with a twin-screw extrusion thread rolling machine, the extrusion thread rolling time is 60 minutes, the temperature is room temperature, and the imported pulp concentration is 18 %, the outlet pulp is 35% thick. The second stage uses a cylindrical refiner for low-consistency beating.

Low consistency beating time 60min, temperature 40 ℃. After the two-stage beating is completed, the beating degree of bamboo fiber pulp is 36.2°SR.

The physical performance indexes of the prepared natural bamboo fiber pulp are: yield 65.2%, average fiber length 1.30 mm, average fiber width 15.0 μm, tightness 0.75 g/m ³ , longitudinal fracture length 3.79 km, transverse ring pressure The strength index is 7.07N·m/g, the longitudinal tear index is 11.36mN·m ² /g, the bursting index is 3.21kPa·m ² /g, the brightness is 38.5% ISO, and the basis weight is 128.6g/m ² .

The result of the obtained natural bamboo fiber biochemical mechanical pulp of the embodiment of the present invention 1 to embodiment 3 and the result obtained from comparative example 1 to 3 are done the following comparative test, and the comparative result is shown in the following table:

Table 1

As can be seen from Table 1, comparative example 1 (only cancels the bamboo chip fermentation section, and all the other techniques and processes are identical with embodiment 1), comparative example 2 (only cancels the nitrogen pressurization in the lye pre-dipping section, is normal pressure, and the remaining techniques are , flow process is identical with embodiment 1), comparative example 3 (nitrogen pressure is canceled in bamboo slice fermentation section and lye pre-dipping section, all the other techniques, flow process are all identical with embodiment 1), with embodiment 1, embodiment 2 and Example 3 are compared, and the yield of the slurry of the comparative example has increased, especially the yield of the comparative example 3 is 78.4%, but the physical properties of the slurry of the comparative example (including longitudinal fracture length, transverse ring pressure index, The longitudinal tear index and burst resistance index, the same below) all decreased, especially the physical properties of the slurry of Comparative Example 3 were the lowest. In addition, it can be seen from the table that the freeness of the pulp of the comparative example is all low, and all are lower than that of Example 1 (the freeness of the pulp is 26.4°SR).

The reason for the analysis is: the cancellation of the fermentation section of bamboo chips means that fermentation can biodegrade the low-cluster substances in the bamboo chips, the intercellular layer and cell wall tissue are damaged to varying degrees, the surface of the bamboo chips is more porous, and the material is softened. It is conducive to the penetration of the subsequent cooking liquid, improves the cooking uniformity and cooking efficiency, and can also reduce the amount of cooking drugs. At the same time, the softening of the bamboo sheet material is beneficial to the subsequent pulp refining, which can separate more complete fibers, reduce the generation of debris, and improve the strength of the pulp after grinding.

Only cancel the nitrogen pressurization in the lye pre-impregnation section and change it to normal pressure operation, which means that the purpose of using nitrogen pressure during lye pre-impregnation (the purpose is to increase the boiling point of the cooking liquid, prevent or reduce the liquid-solid two-phase, that is, the solution and the fiber). At the interface between the raw materials, the generation of steam bubbles that hinder the penetration and transfer of the liquid medicine can keep the transfer coefficient at a high level. On the other hand, increasing the pressure can improve the mass transfer process of the liquid medicine into the fiber raw materials, which is beneficial to the alkali in the bamboo chips. The dissolution of soluble inorganic and organic substances increases the number of voids on the cell wall, which is conducive to the irreversible and permanent softening of bamboo chips, which lays the foundation for subsequent refining. The oxidative degradation of the polybasic, thus ensuring the yield and quality of the pulp after cooking) is gone. For this reason, after alkaline pre-impregnation, there is less dissolution of low clusters and other substances in the slurry, the slurry is coarse and hard, and it is not fully softened, and the yield is higher. Under the same refining conditions, it is not conducive to fiber water absorption and swelling. And fine fiberization, the specific surface area of the fiber is small, the beating degree is difficult to improve, and the physical strength is difficult to improve.

The result of the obtained natural color bamboo fiber biochemical mechanical pulp of the embodiment of the present invention 1 and the result obtained from Comparative Examples 4 to 6 are done the following comparative test, and the comparative result is shown in the following table 2:

Table 2

Known from table 2, comparative example 4 (only cancels the lactic acid bacteria 15% and the rhizopus 10% in the bamboo slice fermentation section, the yeast is changed to 40% from the original 15%, and all the other techniques, flow process are identical with embodiment 1) , Comparative Example 5 (only cancel 10% of the xylanase in the fermentation section of bamboo chips, lipase changes from 15% to 25%, and the rest of the process and process are the same as in Example 1), Comparative Example 6 (in the process of canceling Or low-consistency beating after high-consistency beating, the rest of the process and process are the same as in Example 1), compared with Example 1, the slurry yields of Comparative Examples 4 and 5 are increased by 0.5%-1.1%, but Comparative Examples The physical properties of the slurry (including longitudinal fracture length, transverse ring compression index, longitudinal tear index, and burst resistance index, the same below) all decreased, especially the physical properties of the slurry in Comparative Example 6 were the lowest. In addition, it can be seen from the table that the freeness of the pulp of the comparative example is all low, and all are lower than that of Example 1 (the freeness of the pulp is 26.4°SR).

The reason for the analysis is that the elimination of lactic acid bacteria and rhizopus or xylanase in the fermentation section of bamboo chips means that the role of lactic acid bacteria (functioning fermentable carbohydrates) and rhizopus or xylan does not exist.

Lactic acid bacteria is a general term for a class of non-spore-forming, gram-positive bacteria whose main product of fermented carbohydrates is lactic acid. , to promote the conversion of starch into glucose, while lactic acid bacteria and Rhizopus can improve the weakly acidic environment (pH is about 4-6), so lactic acid bacteria and Rhizopus can biodegrade starch and other low-clustering substances in bamboo, cell The interlayer and cell wall tissue are damaged to varying degrees, the surface of the bamboo slices is more porous, and the material is softened, which is conducive to the penetration of the subsequent cooking liquid, improves the cooking uniformity and cooking efficiency, and can also reduce the amount of cooking drugs. At the same time, the softening of the bamboo sheet material is beneficial to the subsequent pulp refining, which can separate more complete fibers, reduce the generation of debris, and improve the strength of the pulp after grinding. In addition, the hemicellulose in bamboo fiber is mainly xylan hemicellulose, so xylanase can be used for catalytic and highly specific enzymatic hydrolysis of xylan hemicellulose. , forming small voids and softening the material, which is conducive to subsequent cooking and refining.

Therefore, in the slurries of Comparative Examples 4 and 5, the dissolution of starch, low-cluster and other substances is less, and the slurries after pre-impregnation with lye are coarse and hard, not fully softened, and the yield is higher. Under the same refining conditions , which is not conducive to fiber water absorption and swelling and fibrillation. The specific surface area of the fiber is small, the beating degree is difficult to improve, and the physical strength is difficult to improve.

Furthermore, the effect of setting low-consistency beating after medium- or high-consistency beating is that the twisted and entangled fibers of medium- or high-consistency beating can be re-stretched through low-consistency beating, thereby stabilizing the pulp quality and satisfying the pairing of packaging paper. Quality requirements for physical strength of paper. In addition, low-consistency beating can make the fiber bundles and single fibers produced by high-consistency beating further externally and internally fibrillated, and the water retention performance of the fibers is improved, and the cutting damage effect is not large, thereby ensuring the strength of the paper. When the low-consistency beating is cancelled, the beating degree of the pulp is reduced, and the strength of the finished paper is reduced.

The above-mentioned examples are only the preferred embodiments of the present patent, but the protection scope of the present patent is not limited thereto. It should be pointed out that for those of ordinary skill in the art, without departing from the principles of this patent, according to the technical solution of this patent and its patent concept, several improvements and modifications can also be made, and these improvements and modifications should also be regarded as the scope of protection of this patent.

Claims (10)

1. a preparation method of natural bamboo fiber biochemical mechanical pulp, is characterized in that comprising the following steps: 1) material preparation: the material preparation adopts the dry method, that is, bamboo is cut into 10-50mm long and 5-20mm wide bamboo pieces, and the qualification rate reaches more than 85% for standby; the selected bamboo chips, bamboo pith and knots are fermented for standby; 2) Pre-pressing: the bamboo chips obtained in step 1) are sent into the press for pre-pressing, the pre-pressing pressure is 2.5-5.0MPa, the pressing time is 2-10min, and the temperature is normal temperature; 3) Bamboo chip fermentation: adding water to wet the pre-pressed bamboo chips to make their water content 45%-55%; then the animal excrement and the moistened bamboo chips with a water content of 20%-40%, Together with the fine debris such as bamboo chips, bamboo pith and knots screened out in step 1), they are mixed evenly and piled up into long strips, covered with sacks or straw curtains for aerobic fermentation and composting, and high-efficiency activity is added while mixing. biocomposite bacteria; 4) Screening and dedusting: screening and dedusting treatment is carried out after the fermentation, so that the bamboo chips with qualified size after fermentation are separated from other substances after fermentation; the residence time of the fermented bamboo chips in the high-frequency vibration flat sieve is 20-40min; 5) washing: the bamboo chips after screening and dedusting in step 4) are washed to remove surface material and excess moisture through a washing machine, and the moisture content of the bamboo chips after washing and dehydration is 30%-45%; 6) Pre-impregnation of lye: the washed bamboo chips are sent into the cooking container, and alkaline substances are added for lye pre-impregnation. 0.15-0.3MPa; 7) Refining or beating: refining the material pre-impregnated with lye in step (6); 8) Papermaking: the pure bamboo fiber pulp after refining in 7) is made by pulp board, that is, it is obtained. 2. the preparation method of natural bamboo fiber biochemical-mechanical pulp as claimed in claim 1, is characterized in that: in step 2), pre-press adopts double-roller pressing, and upper and lower double-rollers are steel-clad rollers, and both upper and lower rollers have flattening rollers. smooth surface. 3. the preparation method of natural bamboo fiber biochemical-mechanical pulp as claimed in claim 1, is characterized in that: in step 3), the size of stacking long strip is long 2-2.5m, wide 1.5-2m, high 0.8-1m; The stacking time of the strips is 72-120h, and the moisture content of the bamboo chips after fermentation is 14-22%. 4. the preparation method of natural bamboo fiber biochemical-mechanical pulp as claimed in claim 1, is characterized in that: in terms of absolute dry bamboo sheet quality, the consumption of high-efficiency active biological compound bacteria is 2-5%; It is composed of the following raw materials mixed by weight: 15% yeast, 15% lactic acid bacteria, 10% rhizopus, 10% protease, 15% lipase, 15% saccharification enzyme, 10% xylanase, 10% pectinase, The total mass percentage is 100%. 5. the preparation method of natural bamboo fiber biochemical mechanical pulp as claimed in claim 1, is characterized in that: the equipment that screening and dedusting adopts in step 4) is high frequency vibration type flat screen. 6. the preparation method of natural bamboo fiber biochemical mechanical pulp as claimed in claim 1, is characterized in that: the equipment that step 5) washing machine adopts is hydraulic disintegrator, and processing time is 20-40min. 7. the preparation method of natural bamboo fiber biochemical mechanical pulp as claimed in claim 1, is characterized in that: in step 6), with respect to absolute dry raw material quality, the alkaline substance consumption in lye pre-impregnation is 3-7% . 8. the preparation method of natural bamboo fiber biochemical mechanical pulp as claimed in claim 7 is characterized in that: the alkaline substance is the mixture of any one or several substances in sodium hydroxide, potassium hydroxide and sodium sulfite. 9. the preparation method of natural bamboo fiber biochemical mechanical pulp as claimed in claim 1 is characterized in that: in step 8), refining adopts two-stage refining, the first stage adopts medium or high-consistency refining, and the second stage adopts Low-consistency refining; bamboo fiber pulp beating degree is 26-36 ⁰ SR after two-stage beating. 10. the preparation method of natural bamboo fiber biochemical mechanical pulp as claimed in claim 9, it is characterized in that: medium or high consistency beating temperature is room temperature, beating time 80-120min; low consistency beating temperature is 30-50 ℃; beating time 40-60min.