A kind of preparation method of bamboo pulp
Technical field
The present invention relates to a kind of preparation method of bamboo pulp, belong to chemical fiber field.
Background technology
Chemical fibre is as the raw material of textile industry, and its development grows with each passing day, especially the energy day by day the shortage today.Chemical fibre be manufactured on the restriction that is subjected to coal, petroleum resources to a great extent, so people have to fall back on the cellulose fibre again seeking the sight of making fibrous raw material.
Bamboo wood has very rich in natural resources in China, and it is very extensive to distribute, and more than 40 of existing bamboo classes belong to, more than 400 kind, and plantation survives the back 2-3 felling of can growing into forest, and is a kind of plant material of fast growing and high yield., quality the widest to use cizu preferably is example, and its holocellulose content is at 40-50%, and content of lignin is at 20-30%, ash content 1-3%, and pentosan 16-20%, the average length of fiber is the plain raw material of a kind of fiber with excellent at 2.7mm.
Because the structure of bamboo is tightr, cell wall thickness and the footpath, chamber is little, heteroproteose cell content height, appearance has one deck fat wax, and when boiling, the infiltration of chemicals is poor than timber, so when slurrying, multiselect adds the method that multistage is bleached with prehydrolysis sulfate.
The prehydrolytic sulfate process boiling is a kind of the bamboo raw material to be carried out the boiling method that prehydrolysis and sulphate cook combine.In the prehydrolysis stage, the part hemicellulose in the bamboo raw material with the hydrolysis medium effect and change solution over to, remains in hemicellulose in the raw material and also is subjected to a certain degree hydrolysis under high temperature and acid condition, changes the solubility of solution when having improved later soda boiling over to.Prehydrolysis weakens or destroys in the cell membrane skin between the lignin and carbohydrate or carbohydrate connecting to each other, makes the cell membrane skin loose, thereby has created advantage for the infiltration of cooking liquor.
Owing to have the contradiction that whiteness improves and the degree of polymerization descends in the bleaching process, so prior art generally adopts tri-stage bleaching or four sections bleachings just can receive certain effect.
But the situation of prior art is often because processes such as above-mentioned preliminary treatment and bleachings, it is many to exist step, consume big, with serious pollution problem, more representational technical scheme can be disclosed referring to Chinese patent application CN1308160 " a kind of technology of utilizing bamboo wood to produce cellulose viscose pulp ", and its technological process of adopting is: the material → prehydrolysis of getting the raw materials ready → blank → screen → wash → wash material → boiling → batch turning → wash expects → screens → and discongests → desanding → concentrated → chlorination, wash material → alkali refining, wash material → bleaching, wash material → acid treatment → wash material → desanding → concentrate → manufacture paper with pulp; After its boiling, alpha cellulose content 〉=95.5%, starch degree (Ka Bo value) is 4-10, average degree of polymerization DP 〉=600; Bleaching disposed slurry whiteness 〉=75%, average degree of polymerization DP 〉=450, viscosity 〉=7.5mPas, alpha cellulose content 〉=93%.The production method complexity of this technical scheme, technological process are long, the energy resource consumption height, and seriously polluted, the quality control difficulty is big, and the product quality fluctuation is big, is difficult to satisfy the needs of actual production development.
For this reason, the technical staff, reduces and pollutes in the hope of energy savings constantly studying new process.
Summary of the invention
The object of the present invention is to provide a kind of preparation method of bamboo pulp, it is simple that this method has technology, and production procedure is short, and environmental pollution is little, stay-in-grade characteristics, and the pulp that makes is used for the production of viscose.
A kind of preparation method of bamboo pulp, this method may further comprise the steps: get the raw materials ready, boiling, washing, desanding, bleaching, acid treatment, desanding, manufacture paper with pulp, it is characterized in that: described getting the raw materials ready is that bamboo wood is cut sth. askew in the mode that is 10-85 degree angle with its axis, the serial section spacing is 20-40mm, is horseshoe-shape.
Preparation method of the present invention is on the basis of prior art, makes improvements to obtain, and comprises following concrete steps:
1, get the raw materials ready: is horseshoe-shape with bamboo wood according to cross-sectional slices, and bamboo wood is cut sth. askew according to being 10-85 degree angle with its axis, and the serial section spacing is 20-40mm;
2, prehydrolysis: the bamboo chip after will getting the raw materials ready is positioned in the processor, adds entry or acid solution as hydrolyzate, and liquor ratio is 1:3.5-4.0, the 0.65-0.75MPa that keep-ups pressure, and the time kept 100-150 minute, discharge opeing then;
3, boiling: in boiling vessel, add alkali, alkali charge in NaOH to oven dry stock amount 20-30%, liquor ratio 1:3.5-4.0, boiling under pressure 0.65-0.75MPa, boiling 100-150 minute;
4, desanding: the desanding in desander of gained slurry, removing mortar concentration is 0.7-1.5%, desanding pressure is 0.20-0.35MPa;
5, bleaching: the slurry after the desanding carries out one section or two sections bleachings under the condition that contains alkali 60-150g/m3; Described one section bleaching temperature is 40-45 ℃, and chlorinty is 0.20-0.40g/L, bleaching time 30-180 minutes; Described two sections bleachings are meant after above-mentioned one section bleaching carries out second stage bleaching, and the temperature of second stage bleaching is 40-45 ℃, and chlorinty is 0.15-0.30g/L; Bleaching time is 30-180 minute;
Slurry after the bleaching is washed residual acid amount less than 0.20g/L through acid treatment, concentrates, and manufactures paper with pulp, and gets pulp.
Cut sth. askew by being 20-70 degree angle with the bamboo wood axis when preferred above-mentioned bamboo wood is cut into slices among the present invention, the serial section spacing is 20-30mm.
Cut sth. askew by being 40-60 degree angle with the bamboo wood axis when more preferably above-mentioned bamboo wood is cut into slices among the present invention, the serial section spacing is 25mm; Under such angle and spacing, prehydrolysis and boiling can reach best effect, can avoid cellulosic destruction again simultaneously.
Described prehydrolysis temperature is preferably carried out at 165-175 ℃.
In the above-mentioned boiling step, the digestant of adding can be NaOH or Na2O, and alkali charge is for over dry bamboo raw material; Can also add Na again
2S adds Na
2Behind the S, the sulphidity of alkali lye should be 15.0-25.0%.Because the structure of bamboo is tight, cell wall thickness, heteroproteose cell content height, and outer surface has one deck fat wax, when boiling, adds Na
2S can accelerate cooking speed, and the lignin dissolution rate is increased.
The digestant that adds is preferably NaOH and Na2S.
After the above-mentioned boiling, alpha-cellulose content in the slurry 〉=96.5%, average degree of polymerization DP are 550-680.
During desanding, it is dense that the concentration of preferred slurry should be the 0.7-1.0% slurry.
In the above-mentioned blanching step, one section bleaching bleaching liquor is the hypochlorite bleaching liquor, and described hypochlorite is calcium hypochlorite or clorox; Bleaching time is 30-180 minute, is optimized for 60-120 minutes.
During second stage bleaching, bleaching liquor is identical with one section bleaching; Bleaching time is 30-180 minute; Bleaching time is optimized for 40-100 minutes.
The increase of second stage bleaching can make the residual lignin stripping as much as possible in the slurry; Simultaneously, owing to take two sections bleachings, make and reduced the intensity gentleness of whole bleaching process cellulosic degraded influence.
After the above-mentioned bleaching, pulp brightness 〉=77%, average degree of polymerization DP are 450-550, alpha cellulose 〉=94%.
In the preferred process results, slurry viscosity can be 9.5-11.0mPas.
The present patent application adopts the blank mode of " shape of a hoof " to get the raw materials ready, the Unit Weight surface area of raw material bamboo chip is increased, simultaneously, because in bamboo wood when section, is according to cutting sth. askew with bamboo wood axis mode at an angle, the tangent plane that makes culm do identical tubulose fibre bundle correspondence on the cross section increases, in prehydrolysis and digestion process, the rapid osmotic that helps hydrolyzate and cooking liquor, prehydrolysis and cooking effect have been improved, accelerated the dissolution rate of DDGS, the mass ratio of boiling is better, the degree of polymerization is homogeneous relatively, it is abundant that primary wall destroys, the purity of alpha cellulose is also than higher, the link (chlorination or alkali refining) that just can go these to replenish, the pulp of producing can satisfy the use of Viscose Rayon fully, total digestion time of the purified pulp for preparing in patent CN00135021.8 is for being about 11 hours, and total in the present invention digestion time has shortened 4 hours, saved a large amount of energy consumptions, when reaching this purpose, reduce cooking liquor to the cellulose destruction, improved cooking effect and product quality.
Because the minimizing of processing step, make omitted that relevant step takes place in the preparation process wash the material water, water-saving result is obvious, but 50 tons of pulp using water wisely per ton; Specific blank is handled and is made the cooking and heat-preservation time shorten 4 hours, and pulp per ton can be saved 1 ton of steam; Saved chlorination, alkali refining step, pulp per ton can be economized on the about 20Kg of chlorine, economizes on the about 50Kg of alkali, and ton pulp cost descends 120 yuans.
The inventive method compared with prior art, get rid of screening after the boiling, discongested step, owing to adopt specific blank mode, optimized technological parameter, make bleaching adopt the direct bleaching of hypochlorite can realize good result, cancelled chlorination, alkali refining step, energy consumption is reduced significantly; Simultaneously because the shortening of technological process has reduced the pollution that bleachery produces.Therefore, compared with prior art, the inventive method advanced technology, technological process is short, and environmental pollution is little, steady quality, production cost is low, has satisfied the requirement of industrialized production technological progress, has accelerated the utilization and the development of bamboo resource.
The specific embodiment
Embodiment 1
According to cross-sectional slices, cross section and bamboo wood axis are 60 degree angles with bamboo wood, and the serial section spacing is 20mm, is the horseshoe-shape sheet material, and the rotary spherical digester of packing into adds entry, and liquor ratio is 1:3.5, and heat preservation pressure is 0.65Mpa, keeps 150 minutes; Discharge hydrolyzate then.In rotary spherical digester, add NaOH and Na
2The mixed solution of S, NaOH consumption are 20% of over dry raw material weight, and sulphidity is 25.0%, and liquor ratio is 1:3.5, and heat preservation pressure is 0.65MPa, temperature retention time 150 minutes, and boiling finishes, and gets slurry.
The desanding in desander of gained slurry, removing mortar concentration is 0.7%, desanding pressure is 0.30MPa, bleaches in Bellmer then; Adopt a sectional bleaching process, containing alkali 60g/m
3Condition under, temperature is 45 ℃, bleaching time 30 minutes, bleaching chlorinty 0.2g/L; The salt acid treatment of slurry after the bleaching is washed to residual acid amount then and is 0.15g/L, concentrates, and manufactures paper with pulp, and gets pulp.
In the gained pulp, alpha-cellulose content is 95.1%, and moisture is 11.0%, and ash is 0.10%, and whiteness is 80%.
Embodiment 2
According to cross-sectional slices, cross section and bamboo wood axis are 40 degree angles with bamboo wood, and the serial section spacing is 25mm, is the horseshoe-shape sheet material, and the upright steamer of packing into adds entry, and liquor ratio is 1:4, and heat preservation pressure is 0.75Mpa, keeps 100 minutes; Discharge hydrolyzate then.Add alkali lye in rotary spherical digester, alkali is NaOH, and alkali charge is 30% of an over dry raw material weight, and liquor ratio is 1:4, and heat preservation pressure is 0.75MPa, temperature retention time 100 minutes, and boiling finishes, and gets slurry.
The desanding in desander of gained slurry, removing mortar concentration is 0.8%, and desanding pressure is 0.25MPa, bleaches in Bellmer then, adopts a sectional bleaching process, and bleaching contains alkali 150g/m
3, temperature is 40 ℃, bleaching time is 100 minutes, bleaching chlorinty 0.40g/L; The salt acid treatment of slurry after the bleaching is washed to residual acid amount then and is 0.10g/L, concentrates, and manufactures paper with pulp, and gets pulp.
In the gained pulp, alpha-cellulose content is 94.5%, and moisture is 9.0%, and ash is 0.11%, and whiteness is 79%.
Embodiment 3
According to cross-sectional slices, cross section and bamboo wood axis are 50 degree angles with bamboo wood, and the serial section spacing is 40mm, is the horseshoe-shape sheet material, and the rotary spherical digester of packing into adds entry, and liquor ratio is 1:3.8, and heat preservation pressure is 0.70Mpa, keeps 120 minutes; Discharge hydrolyzate then; In rotary spherical digester, add Na
2O and Na
2The mixed solution of S, alkali charge are 25% of over dry raw material weight, and sulphidity is 20.0%, and liquor ratio is 1:3.8, and heat preservation pressure is 0.70MPa, are incubated 120 minutes, and boiling finishes, and get slurry.
The desanding in desander of gained slurry, removing mortar concentration is 0.75%, desanding pressure is 0.20Mpa.Bleach in Bellmer then, adopt a sectional bleaching process, bleaching contains alkali 120g/m
3Condition under, one section bleaching temperature is 42 ℃, the bleaching chlorinty is 0.30g/L, bleaching time is 180 minutes; The salt acid treatment of slurry after the bleaching is washed to residual acid amount then and is 0.15g/L, concentrates, and manufactures paper with pulp, and gets pulp.
In the gained pulp, alpha-cellulose content is 95.7%, and moisture is 8.0%, and ash is 0.12%, and whiteness is 80%.
Embodiment 4
According to cross-sectional slices, cross section and bamboo wood axis are 70 degree angles with bamboo wood, and the serial section spacing is 20mm, is the horseshoe-shape sheet material, the rotary spherical digester of packing into, and adding PH is 5 acid water, and liquor ratio is 1:3.6, and heat preservation pressure is 0.72Mpa, keeps 130 minutes; Discharge hydrolyzate then; In rotary spherical digester, add Na
2O and Na
2The mixed solution of S, alkali charge are 25% of over dry raw material weight, and sulphidity is 20.0%, and liquor ratio is 1:3.8, and heat preservation pressure is 0.72MPa, are incubated 130 minutes, and boiling finishes, and get slurry.
The desanding in desander of gained slurry, removing mortar concentration is 0.75%, desanding pressure is 0.35Mpa.Bleach in Bellmer then, adopt two-sectional bleaching process, one section bleaching is containing alkali 60g/m
3, bleaching temperature is 45 ℃, bleaching chlorinty 0.20g/L, and bleaching time is 30 minutes; Begin second stage bleaching after one section bleaching, bleaching temperature is 45 ℃, and the bleaching chlorinty is 0.30g/L, and bleaching time is 30 minutes; The salt acid treatment of slurry after the bleaching is washed to residual acid amount 0.15g/L then, concentrates, and manufactures paper with pulp, and gets pulp.
In the gained pulp, alpha-cellulose content is 94.7%, and moisture is 9.0%, and ash is 0.10%, and whiteness is 82%.
Embodiment 5
According to cross-sectional slices, cross section and bamboo wood axis are 85 degree angles with bamboo wood, and the serial section spacing is 20mm, be the horseshoe-shape sheet material, the upright steamer of packing into, adding PH are 4.5 acid water, liquor ratio is 1:3.8, and heat preservation pressure is 0.70Mpa, temperature retention time 120 minutes; Discharge hydrolyzate then; In rotary spherical digester, add Na
2O and Na
2The mixed solution of S, alkali charge are 25% of over dry raw material weight, and sulphidity is 20.0%, and liquor ratio is 1:3.8, and heat preservation pressure is 0.70MPa, are incubated 120 minutes, and boiling finishes, and get slurry.
The desanding in desander of gained slurry, removing mortar concentration is 0.75%, desanding pressure is 0.30Mpa.Bleach in Bellmer then, adopt two-sectional bleaching process, one section bleaching contains alkali 150g/m
3Condition under, bleaching temperature is 40 ℃, the bleaching liquor chlorinty is 0.40g/L, bleaching time is 120 minutes; Begin second stage bleaching after one section bleaching, bleaching temperature is 40 ℃, and the bleaching chlorinty is 0.15g/L, and bleaching time is 180 minutes; The salt acid treatment of slurry after the bleaching is washed to residual acid amount then and is 0.15g/L, concentrates, and manufactures paper with pulp, and gets pulp.
In the gained pulp, alpha-cellulose content is 95.2%, and moisture is 8.0%, and ash is 0.10%, and whiteness is 78.3%.
Embodiment 6
According to cross-sectional slices, cross section and bamboo wood axis are 10 degree angles with bamboo wood, and the serial section spacing is 36mm, be the horseshoe-shape sheet material, the upright steamer of packing into, adding PH are 5.5 acid water, liquor ratio is 1:4.0, and heat preservation pressure is 0.70Mpa, temperature retention time 120 minutes; Discharge hydrolyzate then; In rotary spherical digester, add Na
2O and Na
2The mixed solution of S, alkali charge are 25% of over dry raw material weight, and sulphidity is 20.0%, and liquor ratio is 1:3.8, and heat preservation pressure is 0.70MPa, are incubated 120 minutes, and boiling finishes, and get slurry.
The desanding in desander of gained slurry, removing mortar concentration is 0.75%, desanding pressure is 0.30Mpa.Bleach in Bellmer then, adopt two-sectional bleaching process, one section bleaching contains alkali 120g/m
3, bleaching temperature is 42 ℃, and the bleaching chlorinty is 0.30g/L, and bleaching time is 180 minutes; Begin second stage bleaching after one section bleaching, bleaching temperature is 42 ℃, and the bleaching liquor chlorinty is 0.25g/L, and bleaching time is 120 minutes; The salt acid treatment of slurry after the bleaching is washed to residual acid amount then and is 0.15g/L, concentrates, and manufactures paper with pulp, and gets pulp.
In the gained pulp, alpha-cellulose content is 95.1%, and moisture is 7.0%, and ash is 0.10%, and whiteness is 79.9%.