CN113308944A

CN113308944A - Recycled craft paper and preparation method thereof

Info

Publication number: CN113308944A
Application number: CN202110601106.7A
Authority: CN
Inventors: 陈光军; 张永春; 朱琦; 李全勇; 王才林; 卢奇遇; 袁福玉; 张维连; 吴建敏; 熊俊华
Original assignee: Liansheng Paper Industry Longhai Co ltd
Current assignee: Liansheng Paper Industry Longhai Co ltd
Priority date: 2021-05-31
Filing date: 2021-05-31
Publication date: 2021-08-27
Anticipated expiration: 2041-05-31
Also published as: CN113308944B

Abstract

The invention relates to a regenerated craft paper, which comprises a surface layer, a core layer and a bottom layer, wherein the regenerated craft paper is prepared from the following slurry in percentage by weight: 80 to 95 percent of domestic OCC pulp and 5 to 20 percent of wood pulp; the raw material of the domestic OCC pulp is domestic OCC waste paper, and the domestic OCC waste paper comprises 70-80% of domestic waste A-grade paper and 20-30% of domestic waste BC-grade paper; the wood pulp comprises one or more of unbleached softwood pulp, unbleached eucalyptus pulp and roll wood substitute pulp in any proportion; the quantitative ratio of the recycled craft paper is 95-210 g/cm². The invention also relates to a preparation method of the recycled craft paper, which does not use the American waste OCC and the European waste OCC, takes the national waste OCC as a main raw material, optimizes the wood pulp proportion, and optimizes the pulping process of the national waste OCC on the basis, so that 95-210 g/cm can be produced²The A2 craft paper is tough and stable in quality, and solves the problem that 95-210 g/cm of the same quality cannot be produced by using national waste OCC as a main raw material after the national ban on import waste paper²A2 production problems of the ox card.

Description

Recycled craft paper and preparation method thereof

Technical Field

The invention relates to the technical field of papermaking, in particular to a regenerated craft paper and a preparation method thereof.

Background

The recycled craft paper is generally made by pulping the whole waste paper or the main raw material of the waste paper and then producing paper, the cost of the raw material and the energy consumption of the production are relatively low, and the recycled craft paper has very obvious advantages in the field of packaging paper.

The sources of waste paper mainly comprise domestic waste paper and imported waste paper. With the deepening of the implementation of the national environmental protection policy, the country starts to forbid the import of waste paper comprehensively, and domestic waste paper is undoubtedly becoming the main raw material for waste paper papermaking. But compared with the American waste and the European waste, the national waste has the characteristics of short fiber, more recycling times and low strength. Under the market pressure of shortage of raw materials and continuous increase of the national poor quality and price of wastes, the existing raw material conditions cannot be met by utilizing the original process technology, and great difficulty is brought to the manufacture of high-performance recycled craft paper by paper.

Therefore, it is urgently needed to develop a novel preparation method of recycled craft paper, which uses domestic waste OCC as a main raw material to produce a2 recycled craft paper with high strength and good quality.

Disclosure of Invention

In view of the above technical problems, it is desirable to provide a recycled craft paper and a preparation method thereof, so as to solve the production problem that the same quality of a2 recycled craft paper is difficult to produce by using domestic waste OCC as a main raw material after the state prohibits the import of waste paper.

In order to achieve the above object, a first aspect of the present invention provides a recycled craft paper, which includes a surface layer, a core layer and a bottom layer; the recycled craft paper is prepared from the following slurry in percentage by weight: 80 to 90 percent of domestic OCC pulp and 10 to 20 percent of wood pulp;

the raw material of the domestic OCC waste paper is domestic OCC waste paper, and the domestic OCC waste paper comprises 70-80% of domestic waste A-grade paper and 20-30% of domestic waste BC-grade paper;

the wood pulp comprises one or more of unbleached softwood pulp, unbleached eucalyptus pulp and roll wood substitute pulp in any proportion;

the quantitative ratio of the recycled craft paper is 95-210 g/cm²。

A second aspect of the present invention provides a method for preparing recycled craft paper, the recycled craft paper being the recycled craft paper of the first aspect of the present invention, the method comprising the steps of:

s10, preparing domestic waste OCC slurry:

s101: after feeding, disintegrating, removing slag with high concentration and coarse screening the wood pulp package and/or domestic OCC waste paper according to the formula amount, carrying out fiber fractionation to obtain domestic OCC long fiber, domestic OCC medium fiber and domestic OCC short fiber;

s102: carrying out heavy deslagging, fine screening and multi-disc concentration on the domestic OCC long fibers, then selectively carrying out disc grinding and pulping to obtain domestic OCC long fiber pulp, and sending the domestic OCC long fiber pulp to a mixed pulp tank for pulp preparation;

s103: carrying out heavy deslagging, light deslagging, multi-disc concentration and thermal dispersion on the domestic waste OCC medium fiber to obtain domestic waste OCC medium fiber slurry, and sending the domestic waste OCC medium fiber slurry to a mixed slurry pool for slurry preparation;

s104: carrying out heavy deslagging and multi-disc concentration on the domestic waste OCC short fibers to obtain domestic waste OCC short fiber slurry, and sending the domestic waste OCC short fiber slurry to a mixed slurry pool for slurry preparation;

s20, preparation of wood pulp: feeding, disintegrating, removing high-concentration slag, and pulping by a disc mill to obtain wood pulp, and feeding the wood pulp into a mixed pulp tank for pulp blending;

s30 preparation of recycled pulp for broke and bedding: recovering the broken paper and the cushion layer to prepare pulp, and sending the pulp to a mixed pulp tank for pulp blending;

s40, preparing slurry: preparing slurry according to the formula to obtain surface layer slurry, core layer slurry and bottom layer slurry;

s50, paper making: and (3) allowing the surface layer slurry, the core layer slurry and the bottom layer slurry to flow into a pulp flow box through a pulp filling pump and a pressure screen respectively, then sending the pulp flow box into a net part for net part dehydration and forming, and performing squeezing dehydration through a squeezing part, drying through a front drying part, surface sizing, drying through a rear drying part, calendaring, reeling and rewinding to prepare the recycled craft paper.

Be different from prior art, above-mentioned technical scheme provides a regeneration craft paper, including surface course, sandwich layer and bottom, regeneration craft paper is made by following weight percent's thick liquids: 80 to 90 percent of domestic OCC pulp and 10 to 20 percent of wood pulp; the raw material of the domestic OCC waste paper is domestic OCC waste paper, and the domestic OCC waste paper comprises 70-80% of domestic waste A-grade paper and 20-30% of domestic waste BC-grade paper; the wood pulp comprises one or more of unbleached softwood pulp, unbleached eucalyptus pulp and roll wood substitute pulp in any proportion; the quantitative ratio of the recycled craft paper is 95-210 g/cm². The technical scheme also provides a preparation method of the recycled craft paper. In the preparation method, the American waste and the European waste are not used, the A grade and the BC grade of the national waste are used as main raw materials, the wood pulp ratio is optimized, and the domestic waste OCC pulping process is optimized on the basis, so that 95-210 g/cm can be produced²A2 Taurus Chinense (Taurus Chinense) KStrong toughness and stable quality, and solves the problem that the national waste OCC is difficult to produce 95-210 g/cm with the same quality by taking the national waste OCC as the main raw material after the national ban on import waste paper²A2 production problems of the ox card. The used recycled domestic OCC waste paper accounts for 95 percent of all raw materials, meets the requirement of green recycling economic production, has good social and economic benefits, and can be popularized and applied in the field.

Drawings

FIG. 1 is a flow chart of pulping of domestic OCC in a method for preparing recycled craft paper according to an embodiment;

FIG. 2 is a flow chart of pulping wood pulp in a method for preparing recycled craft paper according to an embodiment;

fig. 3 is a flow chart of a paper machine operation in a method for preparing recycled craft paper according to an embodiment.

Detailed Description

In order to explain technical contents, structural features, and objects and effects of the technical means in detail, the following detailed description is given with reference to specific embodiments. The embodiments of the present invention are implemented on the premise of the technical solution of the present invention, and detailed embodiments and specific operation procedures are given, but the scope of the present invention is not limited to the following embodiments.

After the American waste OCC and the European waste OCC are not imported, in the prior art, 100% of national waste OCC is used for papermaking, and under the conditions of normal preparation of pulp, normal papermaking process of a paper machine and normal addition of chemical auxiliary materials, the burst index of the produced kraft paper is 1.7-2.0 kpa²The folding strength is 8-13, the index requirement of A2 craft paper cannot be met, and in fact, the paper reinforcing auxiliary agents such as excessive starch and dry strength agent cannot be used, and the bursting index is not less than or equal to 2.4kpa g/m²And the folding strength is not less than 30 times.

In order to solve the problems in the prior art, the invention provides the recycled craft paper and the preparation method thereof, and the recycled craft paper produced by the recycled craft paper is strong and stable in quality and meets the requirement of 95-210 g/cm²A2 quality index of ox card.

First, a recycled craft paper according to the first aspect of the present invention will be described in detail.

The recycled craft paper in the first aspect of the invention comprises a surface layer, a core layer and a bottom layer; the recycled craft paper is prepared from the following slurry in percentage by weight: 80 to 95 percent of domestic OCC pulp and 5 to 20 percent of wood pulp;

the quantitative ratio of the recycled craft paper is 95-210 g/cm²。

As a further embodiment of the invention, in the recycled kraft paper according to the first aspect of the invention, the wood pulp comprises 10-20% unbleached eucalyptus pulp and 80-90% log pulp, or

The wood pulp comprises 10% of unbleached softwood pulp, 20% -50% of unbleached eucalyptus pulp and 40% -70% of reel wood pulp.

As a further embodiment of the invention, in the recycled craft paper of the first aspect of the invention, the basis weight of the recycled craft paper is 95-130 g/cm²The wood pulp is unbleached softwood pulp or unbleached eucalyptus pulp;

the sizing agent of the surface layer comprises 35-50% of wood pulp and 50-65% of domestic waste OCC medium fiber pulp;

the slurry of the core layer comprises 40-50% of domestic OCC long fiber slurry, 40-50% of domestic OCC short fiber slurry and 10-20% of recycled slurry of broken paper and a cushion layer;

the slurry of the bottom layer comprises 40-50% of domestic waste OCC long fiber slurry, 40-50% of domestic waste OCC short fiber slurry and 10-20% of recycled slurry of broken paper and a cushion layer.

As a further embodiment of the invention, in the recycled craft paper of the first aspect of the invention, the basis weight of the recycled craft paper is 95-130 g/cm²The wood pulp is a roll wood pulp orThe wood pulp comprises 10-20% of unbleached eucalyptus pulp and 80-90% of roll wood substitute, or the wood pulp comprises 10% of unbleached softwood pulp, 20-50% of unbleached eucalyptus pulp and 40-70% of roll wood substitute;

the pulp of the surface layer comprises 25-35% of first wood pulp and 65-75% of domestic OCC (domestic OCC) medium fiber, wherein the first wood pulp comprises 40-50% of components of reel-substitute wood pulp in the wood pulp and other types of pulp components remained in the wood pulp;

the slurry of the bottom layer comprises 40-50% of domestic waste OCC long fiber slurry, 40-50% of domestic waste OCC short fiber slurry and 10-20% of recycled slurry of broken paper and a cushion layer;

the raw materials of the domestic waste OCC long fiber pulp, the domestic waste OCC medium fiber pulp and the domestic waste OCC short fiber pulp comprise domestic OCC waste paper and 50-60% of components of winding drum substituted wood pulp in the wood pulp.

It should be noted that, in the above embodiment, the phrase "the remaining other types of pulp components in the wood pulp" means that the unbleached eucalyptus pulp and/or unbleached softwood pulp in the wood pulp is used in addition to the log pulp.

In addition, it should be noted that the recycled pulp of the broke and the cushion layer is a semi-intermediate product generated in the production process of the recycled craft paper, and is reused in pulp preparation after being recycled and pulped. Wherein, the broke refers to wet broke and dry broke generated in the production process of the pulp on the wire. The wet broke refers to the net part edge cutting paper of the paper machine; the dry broke paper comprises mother roll rewinding edge cutting paper, mother roll residual roll bottom paper, waste paper generated by paper breaking and unqualified product rewinding paper. And (4) re-pulping the wet broke and the dry broke to obtain the broke recycled pulp for recycling the pulp for the core layer and the bottom layer. The cushion recycled pulp is the recycled pulp obtained by processing redundant white water generated in the paper machine manufacturing process by using a white water recycling multi-disc machine. The concrete treatment process of the cushion recycling pulp comprises the following steps: adding partial OCC pulp (usually OCC long-fiber pulp to improve water filtering performance) into white water to form cushion filter cake on a multi-disc fan blade, removing water through the filter cake under the action of vacuum generated by a vacuum water leg of a white water recovery multi-disc machine, intercepting most of fine fibers in the white water by the filter cake to obtain recovery, and stripping the filter cake by using stripping spray water to obtain pulp, namely cushion recovery pulp.

As a further embodiment of the invention, in the recycled craft paper of the first aspect of the invention, the basis weight of the recycled craft paper is 140-210 g/cm²；

The sizing agent of the surface layer comprises 30-90% of wood pulp and 10-70% of domestic waste OCC medium fiber pulp;

As a further embodiment of the present invention, in the recycled craft paper according to the first aspect of the present invention, the face stock comprises 30% to 60% wood pulp and 40% to 70% domestic waste OCC medium fiber pulp.

As a further embodiment of the invention, in the recycled craft paper of the first aspect of the invention, the basis weight of the recycled craft paper is 95-130 g/cm²The bursting index of the recycled craft paper is 2.45-2.50 kpa.g/m²The folding strength is 28-35 times, the color phase value L is 57-59, a is 8.0-8.5, b is 21.0-21.5, and the requirements of A2 craft paper quality index are completely met.

As a further embodiment of the invention, in the recycled craft paper of the first aspect of the invention, the basis weight of the recycled craft paper is 140-210 g/cm²(ii) a The burst index of the recycled craft paper is 2.45-2.50 kpa²The folding endurance is 40-50 times, the hue value L is 57-59, a is 8.0-8.5, b is 21.0-21.5, and the quality index requirement of A2 craft paper is completely met.

Next, a method for preparing recycled craft paper according to the second aspect of the present invention will be described in detail, wherein the recycled craft paper is the recycled craft paper according to the first aspect of the present invention.

The preparation method of the recycled craft paper in the second aspect of the invention comprises the following steps:

s10, preparing domestic waste OCC slurry:

s20, preparation of wood pulp: feeding, disintegrating, removing high-concentration slag, and pulping by a disc mill to obtain wood pulp, and feeding the wood pulp into a mixed pulp tank for pulp blending; said step S20 is optionally performed;

It should be noted that, in the method for preparing recycled craft paper according to the present invention, the step of "pulping with disc mill" in S102 is selectively performed, and the step of "preparing wood pulp" in S20 is also selectively performed. When only roll wood pulp is used in the preparation method (namely the wood pulp is 100 percent roll wood pulp), or the wood pulp comprising 20 percent unbleached eucalyptus pulp and 80 percent roll wood pulp is used, two schemes are provided:

1. 50-60% of components of a reel replacing a wood pulp package in wood pulp are fed into an OCC pulper to be mixed with domestic OCC waste paper for treatment, and long-fiber, medium-fiber and short-fiber pulp is prepared; the 40-50% of the components (and the added unbleached eucalyptus pulp) of the reel wood pulp substitute in the wood pulp are used for sizing the surface layer pulp. At this time, the step of "preparation of pulp" of S20 should be included to prepare the remaining 40% to 50% of the components of the roll substitute wood pulp (and added unbleached eucalyptus pulp) for sizing the face stock. In addition, compared with the condition of no pulping, the improvement of the breaking strength of the paper after the domestic waste OCC is pulped is limited, and the folding strength of the finished paper is reduced by 10 to 20 percent, so that the step of disc grinding and pulping in S102 can be omitted.

2. 100 percent of the reel wood substitute pulp is completely fed into an OCC pulper to be mixed with domestic OCC waste paper for treatment, and long fiber, medium fiber and short fiber pulp is prepared. At this time, the step of S20 "preparation of wood pulp" may not be necessary (including beating without a wood pulp disk mill); and the step of disc grinding and beating in S102 is necessary, and the obtained domestic OCC long fibers are subjected to full disc grinding and beating after the reel wood pulp and the domestic OCC waste paper are mixed, crushed and graded, so that the brooming degree of the long fibers is improved, and the long fiber fine pulp is obtained. Wherein, the disc mill pulping is carried out by a double disc mill pulping machine.

The preparation method of the recycled craft paper provided by the technical scheme has the following beneficial effects:

(1) in the preparation method, the domestic OCC short fiber has less wax point impurities after low-concentration heavy deslagging treatment, and meets the requirements of short fiber pulp preparation and papermaking quality. Therefore, in the preparation method, the actual power of the equipment can be reduced by 1000kw, the power consumption is saved by 12.5kwh/t pulp and the fiber loss is reduced by 7-8 t/d by stopping the primary and secondary light reverse slag removers of the short fibers and the step of clarifying the white water.

(2) In the preparation method, the domestic OCC long fibers have few wax points after being subjected to low-concentration heavy-mass deslagging and fine screening treatment, and the requirements of long fiber pulp preparation and papermaking quality are met. Therefore, in the preparation method, the actual power of the equipment can be reduced by 200kw, the power consumption is saved by 4kwh/t pulp and the fiber loss is reduced by 0.8-1 t/d by stopping the long-fiber light slag remover.

(3) In the preparation method, the domestic OCC long fibers are subjected to low-concentration heavy-mass deslagging, fine screening and multi-disc concentration, so that the adhesive is less, the undispersed fine coating blocks are less, and the quality requirements of long fiber pulp preparation and papermaking are met. Therefore, in the preparation method, the actual power of the equipment can be reduced by 900kwh, the power consumption can be saved by 18kwh/t of paper, and the steam consumption can be saved by 0.08-0.1 t/t of paper by stopping the long fiber thermal dispersion.

(4) In the preparation method, the applicant compares the quality of paper made by pulping domestic waste OCC long fibers by disc grinding and pulping without disc grinding through tests, and finds that compared with the quality of paper made by pulping without disc grinding, the improvement of the bursting strength of the paper made by pulping domestic waste OCC is limited due to the high degree of keratinization of the domestic waste OCC fibers and the poor devillicating and brooming effects of the low-concentration pulping fibers; because the beating machine cuts off the fibers, the length of long fiber is only 0.8-1.0 mm, the fibers are short, the strength of the fibers becomes weak after the cutting off, and the folding endurance of the paper is further influenced, so that the folding endurance of the finished paper after the domestic waste OCC is beaten is reduced by 10% -20% compared with that of the paper without beating. Therefore, in the preparation method, the long fiber double-disc refiner is stopped, so that the actual power of the long fiber double-disc refiner is reduced by 900kwh, and the power consumption is saved by 18kwh/t paper.

(5) In the preparation method, the step of S20 'wood pulp preparation' is selectively carried out, when the wood pulp line is stopped, the power of the wood pulp line equipment (a chain plate machine, a pulper, a pulp pond stirrer, a feeding pump, a wood pulp high-concentration slag remover and a wood pulp disc mill) can be saved by 1500kwh, and the electricity can be saved by 30kwh/t of paper.

(6) In the preparation method, the pulping process is optimized and adjusted, so that electricity can be saved by about 60-70 kwh/t ton of paper, steam can be saved by about 0.08-0.1 t/ton of paper, and waste paper raw materials can be saved by 0.04-0.045 t/ton of paper. The paper machine output is 65 ten thousand tons/year, 3900-4200 ten thousand degrees/year can be saved, 5.2-6.5 ten thousand tons/year of steam can be saved, and 2.6-2.9 ten thousand tons/year of raw materials can be saved.

(7) In the preparation method, the 95-210 g/cm can be produced by only using the national wastes A grade and BC grade without using the American wastes and the European wastes²The A2 craft paper is tough and stable in quality, and solves the problem that the domestic waste OCC is used as a main raw material after the national banned import waste paper is produced, so that 95-210 g/cm with the same quality is difficult to produce²A2 production problems of the ox card. The used recycled domestic OCC waste paper accounts for 95 percent of all raw materials, meets the requirement of green recycling economic production, has good social and economic benefits, and can be popularized and applied in the field.

As a further embodiment of the present invention, in the method for preparing recycled craft paper according to the second aspect of the present invention, the heavy slag removal in steps S102, S103 and S104 is performed by a low-concentration heavy slag remover, and the low-concentration heavy slag remover is provided with a size saver.

By installing the size saver on the low-concentration heavy slag remover of the domestic waste OCC long, medium and short fiber pulping line, the slag discharge rate of the low-concentration heavy slag remover can be effectively adjusted to be 0.045-0.05%, the slag discharge rate is reduced by 0.025-0.03%, the slag discharge ash content of low-concentration tailings is 65-70%, the slag discharge ash content is improved by 5-10%, and the fiber loss is reduced by 30-40 t/d.

The principle of the slurry saver provided by the invention is as follows: the festival thick liquid ware is the ceramic cone, and upper portion is connected with the ceramic lower cone of low dense matter scummer, and open the side has the dilution water connector, and the dilution water gets into festival thick liquid ware along the tangent line, reduces thick liquids concentration, reinforcing vortex intensity, plays the elutriation effect, can effectively improve the separation efficiency of fibre and heavy impurity, effectively reduces useful fibre and discharges along with the tailings to improve the purifying effect of thick liquids. The slag discharging nozzle is positioned at the bottom of the slurry saver, and the glass slag discharging pipe is used for connecting the slag discharging nozzle and the slag discharging main pipe, so that the slag discharging condition can be conveniently checked.

As a further embodiment of the present invention, in the method for preparing recycled craft paper according to the second aspect of the present invention, the method further comprises the steps between the fine screen and the multi-disk concentration in step S102:

and refluxing the tailings obtained after fine screening to a disintegration stage, and then carrying out disintegration again.

In this preparation method, the fine screen load is low and there are few undispersed paper fragments in the tailings produced. Therefore, in the preparation method, the tailings generated after fine screening are returned to the pulper for secondary disintegration, so that the fine screening slag discharge rate can be effectively adjusted to be 0.007-0.010%, and the fiber loss is reduced by 5-15 t/d.

As a further embodiment of the present invention, in the method for producing recycled craft paper according to the second aspect of the present invention, in the wood pulp:

the disintegrating concentration of unbleached softwood pulp is 4.0-5.0%, the pulping concentration is 4.0-5.0%, the beating degree of an outlet of a disc mill is 32-36 DEG SR, and the wet weight of fiber at the outlet of the disc mill is 12-14 g;

the disintegration concentration of unbleached eucalyptus pulp is 4.0-5.0%, the pulping concentration is 4.0-5.0%, the beating degree of an outlet of a disc mill is 32-36 DEG SR, and the wet weight of fibers at the outlet of the disc mill is 2-3 g;

the disintegration concentration of the reel wood pulp substitute is 4.0-5.0%, the beating concentration is 4.0-5.0%, the beating degree of the outlet of the disc mill is 32-36 DEG SR, and the wet weight of the outlet fiber of the disc mill is 12-14 g.

As a further embodiment of the present invention, in the method for preparing recycled craft paper according to the second aspect of the present invention:

the beating degree of the domestic waste OCC long fiber pulp is 32-36 DEG SR, and the wet weight is 5.5-6.0 g;

the beating degree of fiber pulp in the domestic waste OCC is 35-40 DEG SR, and the wet weight is 4.5-5.0 g;

the beating degree of the domestic waste OCC short fiber pulp is 36-42 DEG SR, and the wet weight is 4.0-4.5 g.

the beating degree of the domestic waste OCC long fiber pulp is 32-36 DEG SR, and the wet weight is 6.0-7.5 g;

the beating degree of fiber pulp in the domestic waste OCC is 35-40 DEG SR, and the wet weight is 5.0-6.0 g;

the beating degree of the domestic waste OCC short fiber pulp is 36-42 DEG SR, and the wet weight is 4.0-5.0 g;

the beating degree of the domestic waste OCC long fiber pulp is 32-36 DEG SR, and the wet weight is 7.0-9.0 g;

the raw materials of the domestic waste OCC long fiber pulp, the domestic waste OCC medium fiber pulp and the domestic waste OCC short fiber pulp comprise domestic OCC waste paper and 100% winding drum wood pulp in wood pulp.

As a further embodiment of the present invention, in the method for preparing recycled craft paper according to the second aspect of the present invention, in step S50, before the "feeding into the web section", the method further comprises: AKD (water-resistant sizing agent), dry strength agent, aluminum sulfate, solid retention aid, emulsion retention aid, defoaming agent, bactericide and dye are respectively added into the surface layer slurry, the core layer slurry and the bottom layer slurry.

In the method for preparing recycled craft paper according to the second aspect of the invention, preferably, the addition amount of AKD is 1-12 kg/t paper. The water absorption of the paper can be effectively improved by adding 1-12 kg/t of AKD of the paper.

Preferably, the addition amount of the dry strength agent is 10-25 kg/t of paper. The dry strength agent of 10-25 kg/t paper is added, so that the bursting strength of the paper can be improved.

Preferably, the adding amount of the aluminum sulfate is 4-8 kg/t of paper. The pH value of the online slurry can be controlled to be 6.5-7.0 by adding 4-8 kg/t of paper aluminum sulfate.

Preferably, the addition amount of the solid retention aid is 0.2-0.3 kg/t of paper; the addition amount of the emulsion retention aid is 0.2-0.3 kg/t of paper. By adding 0.2-0.4 kg/t paper solid retention aid and 0.2-0.3 kg/t paper emulsion retention aid, the net part retention rate can be effectively improved to 50-60%, and the net white water concentration is adjusted to 0.3-0.5%.

Preferably, the addition amount of the defoaming agent is 0.2-0.4 kg/t of paper. By adding 0.2-0.4 kg/t paper defoaming agent, the foam condition of a paper machine system can be effectively improved and adjusted, and the air content of the pulp on the screen is adjusted to 1.5-2.5%.

Preferably, the addition amount of the bactericide is 0.05-0.1 kg/t of paper. By adding the bactericide, the bacteria content in slurry and white water of the approach system can be effectively reduced to be less than 10⁸And the cleanness of a normal system is maintained.

Preferably, the adding amount of the dye is 2.5-3.5 kg/t of paper. By adding the dye, the values of the paper color phases L, a and b can be controlled within a qualified range.

It should be noted that, in the following specific examples, the addition amounts of the chemical auxiliary materials such as AKD, dry strength agent, aluminum sulfate, solid retention aid, emulsion retention aid, defoamer, bactericide, dye, etc. may be adjusted within the above ranges by those skilled in the art according to specific process conditions to meet the corresponding process requirements, so that the specific addition amounts of the chemical auxiliary materials are not specifically listed in the specific examples. As a further embodiment of the present invention, in the method for producing recycled craft paper according to the second aspect of the present invention, in the "surface sizing" process in step S50, a surface sizing agent and a surface sizing starch are added.

In the method for preparing the recycled craft paper with high gram weight according to the second aspect of the invention, preferably, the addition amount of the surface sizing agent is 1.5-2.5 kg/t paper. The surface sizing agent of 1.5-2.5 kg/t paper is added to further improve the water absorption of the paper, and the water absorption cobb value of the surface layer is adjusted to be 30-40 g/m²The cobb value of the bottom layer is 30-40 g/m²。

In the method for preparing recycled craft paper according to the second aspect of the invention, preferably, the addition amount of the surface sizing starch is 40-45 kg/t paper. Sizing starch on the surface of paper by 40-45 kg/t,the bursting strength of the finished paper can be further improved, so that the bursting index of the finished paper is controlled to be 2.4-2.5 kpa²The folding endurance is 25-45 times.

The present invention is further illustrated by the following specific examples of recycling craft paper through a2, but the scope of the present invention is not limited thereto.

Materials, reagents, equipment and the like used in the embodiments of the present invention are commercially available unless otherwise specified; the adopted process methods, conditions and the like are conventional methods and conditions unless specified otherwise. For example, but not limited to, domestic OCC waste paper used in the embodiment of the invention is waste cardboard paper subjected to double sorting, and the goods source is from supermarkets, industrial and commercial institutions.

Example 1 sheet testing of American, European and national waste materials

In the embodiment, the raw materials of the American waste, the European waste and the national waste are subjected to disintegration, deslagging, screening and purification and are concentrated to slurry, the slurry is respectively fluffed to be uniform, then the sheet making tests are respectively carried out, and the sheet making ration is 100g/cm²The test results are averaged after three determinations. The test results are shown in table 1.

TABLE 1 sheet test results of American, European and national wasters

As can be seen from Table 1, the length of the beautiful waste fiber is good, the fiber strength is high, and the rupture strength and the folding strength of the beautiful waste OCC raw material sheet are high; the properties of the Europe waste are inferior; the average fiber length of the domestic waste OCC raw material sheet is low, the fiber bonding force is poor, the fiber strength is low, and the bursting strength and the folding strength are not as good as those of American waste and European waste. And the grade A, B, C and D burst strength and folding endurance of the national wastes are low. The grade D is the worst, the impurity content of the mixed paper is high, the ash content is high, and the quality of the paper surface and the strength of the finished paper are influenced when the mixed paper is used for papermaking of kraft paper; the color L value of the C-grade national waste copy sheet is higher than that of the A-grade national waste and B-grade national waste.

Therefore, after considering the strength and color of domestic waste materials, in the embodiment of the present invention, it is preferable that the ratio of domestic OCC is: 70-80% of the national waste A grade and 20-30% of the national waste BC grade. Preferably, the mixture ratio of the domestic OCC is as follows: 70-80% of the national waste A grade, 10-25% of the national waste B grade and 5-10% of the national waste C grade. When the color L value of finished paper is lower than 56, the national waste C grade proportion can be increased to 10%.

Example 2 sheet testing of Wood pulp

In this example, unbleached sulfate softwood pulp (unbleached softwood pulp), unbleached sulfate broadleaf pulp (unbleached eucalyptus pulp), and imported reel recycled pulp (reel wood-substituted pulp, fiber component is 100% chemical pulp) were subjected to disintegration, deslagging, disc milling and pulping to obtain pulp, and then sheet making tests were respectively performed, with test results shown in table 2; meanwhile, the different wood pulps were subjected to matching sheet making tests, and the test results are shown in table 3. The test results are all averaged after three determinations.

TABLE 2 sheet test results for wood pulp

As can be seen from Table 2, unbleached sulfate needle pulp has the best burst index and folding strength. While the bursting index and folding strength of unbleached eucalyptus pulp and wound-roll wood pulp are lower than those of unbleached softwood pulp, the unbleached softwood pulp and wound-roll wood pulp are economical to supply, and therefore, the unbleached eucalyptus pulp and wound-roll wood pulp are used as substitute pulp for production tests in the following specific examples.

TABLE 3 sheet test results for different wood pulp ratios

As can be seen from Table 3, when unbleached eucalyptus pulp and roll wood pulp were blended at different ratios, the burst strength of the sheets did not change much. Unbleached eucalyptus pulp and wound roll pulp are mixed in a ratio of 1: 9, the folding endurance of the sheet can reach 1876 times when the sheet is prepared according to the proportion of 2: when the paper is prepared according to the proportion of 8, the folding resistance of the prepared paper can reach 1714 times; after the proportion of unbleached eucalyptus pulp is increased, the folding resistance of the sheet is reduced from 1714 times to 700 times, and the reduction amplitude is large. When unbleached eucalyptus pulp, reel wood substitute pulp and unbleached softwood pulp are mixed and copied according to different proportions, the breaking strength of the copied paper is not changed greatly, and the folding endurance is lower than that of the unbleached eucalyptus pulp and reel wood substitute pulp.

By combining the above analysis, 100% unbleached softwood pulp, or 100% roll wood pulp, or the unbleached eucalyptus pulp and roll wood pulp are mixed in a ratio of 1: 9-2: 8, mixing the composite pulp or the unbleached softwood pulp, the unbleached eucalyptus pulp and the reel wood pulp in a ratio of 1: (2-5): (4-7) the sheet made of the composite slurry mixed according to the proportion is high in burst strength and folding strength.

Therefore, in the embodiment of the invention, the wood pulp is preferably 100% unbleached softwood pulp, or 100% roll wood pulp, or 100% unbleached eucalyptus pulp, or the unbleached eucalyptus pulp and roll wood pulp in a ratio of (1-2): (8-9) mixing the composite pulp or the unbleached softwood pulp, unbleached eucalyptus pulp and winding drum wood pulp by the ratio of 1: (2-5): (4-7) mixing the components in proportion.

Example 3 sheet bench of slurry

In this embodiment, domestic OCC waste paper is first subjected to disintegration, high concentration residue removal, coarse screening, fiber classification, short fiber heavy residue removal, and short fiber concentration to obtain domestic OCC short fiber pulp. And then, carrying out a paper making test on the domestic OCC short fiber pulp (the raw material ratio is 60% of the A-grade domestic waste and 40% of the B-grade domestic waste) and the wood pulp, wherein the test results are obtained by taking an average value after three times of measurement. The test results are shown in tables 4 and 5.

TABLE 4 sheet test results for unbleached eucalyptus pulp and fluff pulp

TABLE 5 sheet test results for unbleached needle pulp and fluff pulp

TABLE 6 sheet making test results of reel wood pulp and fluff pulp

As can be seen from Table 4, the 10% -30% unbleached eucalyptus pulp and OCC fluff pulp have a burst strength of 1.54-1.85 kpa.m when mixed and made into tablets²The per g is 0.1 to 0.41kpa.m higher than that of 100 percent OCC short fiber sheet making²/g。

As is clear from Table 5, when 5% unbleached needlebush pulp and OCC fluff pulp were blended and the bursting strength of the sheet was 1.59kpa.m²The per g is improved by 0.15kpa.m compared with 100 percent OCC short fiber sheet making²(ii)/g; 20 percent unbleached needle leaf pulp and domestic waste OCC short fiber pulp are mixed and made into sheets, and the burst strength of the sheets is 2.53kpa²The per g is improved by 1.09kpa.m compared with 100 percent OCC short fiber sheet making²(ii)/g; when the addition amount of the unbleached needle pulp is increased from 20 percent to 30 percent, the burst strength is not changed too much.

As can be seen from Table 6, the breaking resistance index of the paper made by using 5-20% reel wood pulp and short fibers is 1.57-1.98 kpa.m2/g, which is 0.13-0.54 kpa.m2/g higher than that of 100% OCC short fiber, the folding resistance is 9-35 times, and is 4-30 times higher than that of 100% OCC short fiber.

It can be known from tables 4, 5 and 6 that the paper bursting strength and the folding strength can be effectively improved by using the domestic waste OCC as the main raw material and adding part of wood pulp. In the embodiment of the present invention, preferably, the adopted raw material proportioning process scheme includes: 5% -20% of unbleached softwood pulp and 80% -95% of domestic waste OCC; or 5% -20% of reel wood pulp and 80% -95% of domestic waste OCC; or 10 to 30 percent of unbleached eucalyptus pulp and 70 to 90 percent of national waste; or any two or three of softwood pulp, wound roll wood pulp and unbleached eucalyptus pulp are matched and used simultaneously, the proportion of the wood pulp is 5-20%, and the proportion of the wood pulp is 80-95%.

Example 4A2 production of Takara 1 #paper

1. The raw material ratio is as follows:

(1) wood pulp proportioning: 100% unbleached softwood pulp.

(2) The domestic OCC waste paper ratio: 70 percent of A-grade national waste and 30 percent of BC-grade national waste (20 to 25 percent of B-grade national waste and 5 to 10 percent of C-grade national waste, when the color L value is lower than 56, the proportion of the C-grade national waste is improved to 10 percent).

(3) Proportioning the slurry: 5 to 15 percent of wood pulp and 85 to 95 percent of domestic waste OCC pulp.

2. Preparing slurry for the surface layer, the core layer and the bottom layer:

(1) surface layer: all wood pulp is added in the surface layer, the proportion of the wood pulp in the surface layer is 35-50%, and the proportion of the fiber in the OCC is 50-65%.

(2) Core layer: the proportion of OCC long fibers is 40-50%, the proportion of short fibers is 40-50%, and the proportion of broke and cushion recycled pulp is 10-20%.

(3) Bottom layer: the proportion of OCC long fibers is 40-50%, the proportion of short fibers is 40-50%, and the proportion of broke and cushion recycled pulp is 10-20%.

3. Referring to fig. 1, the preparation of domestic OCC slurry includes the following steps:

(1) the domestic OCC waste paper with the formula amount is subjected to feeding, crushing, high-concentration slag removal and coarse screening, and then is subjected to fiber fractionation to be selected into domestic OCC long fibers, domestic OCC medium fibers and domestic OCC short fibers.

(2) And carrying out heavy deslagging, fine screening and multi-disc concentration on the domestic waste OCC long fibers to obtain domestic waste OCC long fiber pulp, and sending the domestic waste OCC long fiber pulp to a mixed pulp tank for pulp preparation.

(3) And carrying out heavy deslagging, light deslagging, multi-disc concentration and thermal dispersion on the domestic waste OCC medium fiber to obtain domestic waste OCC medium fiber slurry, and sending the domestic waste OCC medium fiber slurry to a mixed slurry pool for slurry preparation.

(4) And carrying out heavy deslagging and multi-disc concentration on the domestic waste OCC short fibers to obtain domestic waste OCC short fiber slurry, and sending the domestic waste OCC short fiber slurry to a mixed slurry pool for slurry preparation.

4. Referring to fig. 2, the preparation of wood pulp comprises the following steps:

the pulp bag of unbleached softwood pulp with the formula amount is subjected to feeding, disintegration, high-concentration slag removal and disc mill pulping to obtain wood pulp, and the wood pulp is sent to a mixed pulp tank for pulp preparation.

5. Preparing broke and cushion recycling pulp:

and recovering the broke and the cushion layer generated in the production process, pulping again to obtain recovered pulp of the broke and the cushion layer, and sending the recovered pulp to a mixed pulp tank for pulp blending.

6. Slurry preparation: and (4) preparing slurry according to the formula to obtain surface layer slurry, core layer slurry and bottom layer slurry.

7. The paper making process, please refer to fig. 3, includes the following steps:

respectively enabling the surface layer slurry, the core layer slurry and the bottom layer slurry obtained by slurry mixing to flow into a surface layer slurry head box, a core layer slurry head box and a bottom layer slurry head box through a slurry filling pump and a pressure screen; respectively adding AKD, a dry strength agent, aluminum sulfate, a solid retention aid, an emulsion retention aid, a defoaming agent, a bactericide and a dye into the surface layer slurry, the core layer slurry and the bottom layer slurry; and then the recycled craft paper is sent to a net part to be dewatered and formed, and is subjected to press dewatering by a pressing part, drying by a front drying part, surface sizing, drying by a rear drying part, press polishing, reeling and rewinding to prepare the recycled craft paper. Wherein, in the surface sizing process, a surface sizing agent and surface sizing starch are added.

8. The properties of the slurry are as follows:

the disintegration concentration of wood pulp is 4.0-5.0%, the beating concentration is 4.0-5.0%, the beating degree of an outlet of a disc mill is 32-36 DEG SR, and the wet weight of outlet fibers of the disc mill is 12-14 g.

9. The paper index test results of the recycled kraft paper are shown in table 7.

Table 7 paper index test result table of recycled craft paper

The results in Table 7 show that the unbleached softwood pulp is used in an amount of 76-84 kg/t, the unit consumption of surface adhesive starch is 42-43 kg/t, and the unit consumption of dry strength agent is 13-15 kg/t. The paper has the indexes of breaking resistance, folding resistance and color phase reaching A2 Taka standard.

Example 5A2 production of Takara 2 #paper

1. The raw material ratio is as follows:

(1) wood pulp proportioning: 100% import recycled pulp (reel wood pulp).

(2) The domestic OCC waste paper ratio: 70% of grade A country waste and 30% of grade BC country waste.

2. Preparing slurry for the surface layer, the core layer and the bottom layer:

(1) surface layer: the first wood pulp is 25-35% in proportion, and the domestic waste OCC medium fiber is 65-75% in proportion. Wherein, the first wood pulp comprises 40 to 50 percent of the components of the roll wood pulp in the wood pulp.

Wherein, 50 to 60 percent of the components of the reel replacing the wood pulp package in the wood pulp are fed into an OCC pulper to be mixed with domestic OCC waste paper for processing, and long fiber, medium fiber and short fiber pulp are prepared.

In this embodiment, 3, preparation of domestic OCC pulp → 7, and paper making are the same as those in embodiment 4, except that the wood pulp used in this embodiment is a roll wood pulp substitute, and the domestic OCC pulp of long fibers, medium fibers, and short fibers is prepared by mixing the roll wood pulp substitute and domestic OCC waste paper.

8. The properties of the slurry are as follows:

The properties of the national waste OCC long fiber, medium fiber and short fiber pulp prepared by mixing and processing the winding drum wood pulp and the domestic OCC waste paper are as follows:

the beating degree of the domestic waste OCC short fiber pulp is 36-42 DEG SR, and the wet weight is 4.0-5.0 g.

9. The paper index test results of the recycled kraft paper are shown in table 8.

Table 8 paper index test result table of recycled craft paper

The results in Table 8 show that the consumption of the reel instead of wood pulp is 86-91 kg/t, the unit consumption of the surface sizing starch is 43kg/t, and the unit consumption of the dry strength agent is 8-10 kg/t. The indexes of the paper breaking resistance and the folding resistance reach the A2 Taka standard, but the L value of the paper color index is 55-56 and is slightly lower than the L value 57-59 of the A2 Taka standard. Based on the method, the L value of the finished paper of the embodiment can be improved to the A2 Taka standard by increasing the proportion of the C grade domestic waste or adding a proper proportion of unbleached eucalyptus pulp and/or unbleached softwood pulp with the L value larger than 68.

Example 6A2 production of Takara 3 #paper

1. The raw material ratio is as follows:

(1) wood pulp proportioning: 100% unbleached sulfate broad leaf pulp (unbleached eucalyptus pulp).

(3) Proportioning the slurry: 10 to 15 percent of wood pulp and 85 to 90 percent of domestic waste OCC pulp.

2. Preparing slurry for the surface layer, the core layer and the bottom layer:

In this example, 3, preparation of domestic waste OCC pulp → 7, and the specific steps of paper making were the same as in example 4, except that the wood pulp used in this example was unbleached eucalyptus pulp.

8. The properties of the slurry are as follows:

the disintegration concentration of wood pulp is 4.0-5.0%, the beating concentration is 4.0-5.0%, the beating degree of an outlet of a disc mill is 32-36 DEG SR, and the wet weight of outlet fibers of the disc mill is 2-3 g.

9. The paper index test results of the recycled kraft paper are shown in table 9.

Table 9 paper index test result table of recycled craft paper

The results in Table 9 show that the unbleached eucalyptus pulp is used in an amount of 120-150 kg/t, the surface sizing starch is consumed in an amount of 43-45 kg/t, and the dry strength agent is consumed in an amount of 8-15 kg/t. The indexes of the finished paper, such as breakage resistance and folding resistance, reach the A2 Taka standard, the color L value is 57-58, and the color L value better reaches the A2 Taka standard L value of 57-59.

Example 7A2 production of Takara 4 #paper

1. The raw material ratio is as follows:

(1) wood pulp proportioning: 80% imported recycled pulp (roll wood pulp), 20% unbleached eucalyptus pulp.

2. Preparing slurry for the surface layer, the core layer and the bottom layer:

(1) surface layer: the first wood pulp is 25-35% in proportion, and the domestic waste OCC medium fiber is 65-75% in proportion. Wherein the first wood pulp comprises 40-50% of the components of the roll-substitute wood pulp in the wood pulp and all unbleached eucalyptus pulp added.

Wherein, the rest 50-60% of the components of the reel-substituted wood pulp in the wood pulp are fed into an OCC pulper to be mixed with domestic OCC waste paper for treatment, and long fiber, medium fiber and short fiber pulp are prepared.

In this example, 3, preparation of domestic OCC pulp → 7, and paper making are the same as in example 4, except that the wood pulp used in this example is roll wood pulp and unbleached eucalyptus pulp, and the domestic OCC pulp of long fibers, medium fibers, and short fibers is mixed with the roll wood pulp and domestic OCC waste paper.

8. The properties of the slurry are as follows:

the disintegration concentration of wood pulp (80% of roll wood pulp and 20% of unbleached eucalyptus pulp) is 4.0% -5.0%, the beating concentration is 4.0% -5.0%, the beating degree of an outlet of a disc mill is 32-36 DEG SR, and the wet weight of fiber at the outlet of the disc mill is 11-14 g.

9. The paper index test results of the recycled kraft paper are shown in table 10.

TABLE 10 paper index test result table of recycled craft paper

The results in Table 10 show that the consumption of wood pulp (80% of roll wood pulp and 20% of unbleached eucalyptus pulp) is 85-101 kg/t of paper, the unit consumption of surface sizing starch is 43-52 kg/t, and the unit consumption of dry strength agent is 7.4-12 kg/t. The paper has the indexes of breaking resistance, folding resistance and color phase reaching A2 Taka standard.

EXAMPLE 8A2 production of 5# Takara paper

1. The raw material ratio is as follows:

(1) wood pulp proportioning: 100% import recycled pulp (reel wood pulp).

(3) Proportioning the slurry: 8 to 12 percent of wood pulp and 88 to 92 percent of domestic waste OCC pulp.

2. Preparing slurry for the surface layer, the core layer and the bottom layer:

(1) surface layer: the proportion of the domestic waste OCC medium fiber is 100 percent.

Wherein, the pulp bags of 100 percent of the reel wood pulp are all fed into an OCC pulper to be mixed with domestic OCC waste paper for treatment, and long fiber, medium fiber and short fiber pulp is prepared.

(1) the method comprises the steps of feeding, disintegrating, removing high-concentration slag and roughly screening the winding drum wood pulp and domestic OCC waste paper according to the formula amount, and then carrying out fiber grading separation on the winding drum wood pulp and domestic OCC waste paper to obtain domestic OCC long fibers, domestic OCC medium fibers and domestic OCC short fibers.

(2) And carrying out heavy residue removal, fine screening, multi-disc concentration and disc grinding pulping on the domestic OCC long fibers to obtain domestic OCC long fiber pulp, and sending the domestic OCC long fiber pulp to a mixed pulp tank for pulp preparation. Among them, the "disc mill beating" is necessary only in the present embodiment, and is not shown in fig. 1.

4. Preparing broke and cushion recycling pulp:

5. Slurry preparation: and (4) mixing slurry according to the formula amount to obtain surface layer slurry, core layer slurry and bottom layer slurry.

6. The paper making process, please refer to fig. 3, includes the following steps:

7. The properties of the slurry are as follows:

8. The paper index test results of the recycled kraft paper are shown in table 11.

Table 11 paper index test result table of recycled craft paper

The results in Table 11 show that the consumption of the reel instead of wood pulp is 90-96 kg/t, the unit consumption of the surface sizing starch is 42-45 kg/t, and the unit consumption of the dry strength agent is 8-10 kg/t. The indexes of the finished paper, such as breaking resistance, folding resistance and color value, all reach A2 Taka standards.

In addition, 100% of the reel wood-substitute pulp is completely fed into the OCC pulper to be mixed with domestic OCC waste paper for treatment, so that long-fiber, medium-fiber and short-fiber pulp is prepared. Therefore, the wood pulp line is stopped, the power of wood pulp line equipment (a chain plate machine, a pulper, a pulp pond stirrer, a feeding pump, a wood pulp high-concentration slag remover and a wood pulp disc mill) can be saved by 1500kwh, and the power can be saved by 30kwh/t paper.

Example 9A2 production of Takara 6 #paper

1. The raw material ratio is as follows:

(1) wood pulp proportioning: 100% unbleached softwood pulp.

(2) The domestic OCC waste paper ratio: 80% of A-grade national waste and 20% of BC-grade national waste.

2. Preparing slurry for the surface layer, the core layer and the bottom layer:

(1) surface layer: all wood pulp is added in the surface layer, the proportion of the wood pulp in the surface layer is 50-80%, and the proportion of the fiber in the OCC is 20-50%.

In this example, 3, preparation of domestic waste OCC pulp → 7, and specific steps of paper making were the same as in example 4.

8. The properties of the slurry are as follows:

9. The paper index test results of the recycled kraft paper are shown in table 12.

Table 12 paper index test result table of recycled craft paper

The results in Table 12 show that the unbleached softwood pulp is used in an amount of 120-135 kg/t, the unit consumption of surface adhesive starch is 42-48 kg/t, and the unit consumption of dry strength agent is 8-10 kg/t. The paper has the indexes of breaking resistance, folding resistance and color phase reaching A2 Taka standard.

Example 10A2 production of 7# Takara paper

1. The raw material ratio is as follows:

(1) wood pulp proportioning: 100% import recycled pulp (reel wood pulp).

(3) Proportioning the slurry: 15 to 20 percent of wood pulp and 80 to 85 percent of domestic waste OCC pulp.

2. Preparing slurry for the surface layer, the core layer and the bottom layer:

(1) surface layer: the wood pulp is completely added in the surface layer, the proportion of the wood pulp in the surface layer is 60% -90%, and the proportion of the fibers in the domestic OCC is 10-40%.

In this example, 3, preparation of domestic waste OCC pulp → 7, and the specific steps of paper making are the same as in example 4, except that the wood pulp used in this example is a roll of wood pulp instead.

8. The properties of the slurry are as follows:

9. The paper index test results of the recycled kraft paper are shown in table 13.

Table 13 paper index test result table of recycled craft paper

The results in Table 13 show that the consumption of the reel instead of wood pulp is 152-162 kg/t, the unit consumption of the surface sizing starch is 42-48 kg/t, and the unit consumption of the dry strength agent is 6-10 kg/t. The indexes of the finished paper, such as breaking resistance, folding resistance and color value, all reach A2 Taka standards.

EXAMPLE 11A2 production of 8# Takara paper

1. The raw material ratio is as follows:

2. Preparing slurry for the surface layer, the core layer and the bottom layer:

(1) surface layer: all wood pulp is added in the surface layer, the proportion of the wood pulp in the surface layer is 60% -90%, and the proportion of the fiber in the OCC is 10-40%.

8. The properties of the slurry are as follows:

9. The paper index test results of the recycled kraft paper are shown in table 14.

Table 14 paper index test result table of recycled craft paper

The results in Table 14 show that the consumption of the reel instead of wood pulp is 149-168 kg/t, the unit consumption of the surface sizing starch is 35-45 kg/t, and the unit consumption of the dry strength agent is 5-8 kg/t. The indexes of the finished paper, such as breaking resistance, folding resistance and color value, all reach A2 Taka standards.

Example 12A2 production of Takara 9 #paper

1. The raw material ratio is as follows:

(1) wood pulp proportioning: 90% imported recycled pulp (wound roll pulp) and 10% unbleached eucalyptus pulp.

2. Preparing slurry for the surface layer, the core layer and the bottom layer:

(1) surface layer: all wood pulp is added in the surface layer, the proportion of the wood pulp in the surface layer is 30-60%, and the proportion of the fiber in the OCC is 40-70%.

In this example, 3, preparation of domestic waste OCC pulp → 7, and the specific steps of paper making were the same as in example 4, except that the wood pulp used in this example was roll wood pulp and unbleached eucalyptus pulp.

8. The properties of the slurry are as follows:

the disintegration concentration of wood pulp (70% of roll wood pulp and 30% of unbleached eucalyptus pulp) is 4.0% -5.0%, the beating concentration is 4.0% -5.0%, the beating degree of an outlet of a disc mill is 32-36 DEG SR, and the wet weight of fiber at the outlet of the disc mill is 11-14 g.

9. The paper index test results of the recycled kraft paper are shown in table 15.

Table 15 paper index test result table of recycled craft paper

The results in Table 15 show that the consumption of wood pulp (90% of roll wood pulp and 10% of unbleached eucalyptus pulp) is 103-116 kg/t of paper, the unit consumption of surface sizing starch is 33.5-48 kg/t, and the unit consumption of dry strength agent is 17-24 kg/t. The paper has the indexes of breaking resistance, folding resistance and color phase reaching A2 Taka standard.

Example 13A2 production of Takara 10 #paper

1. The raw material ratio is as follows:

(1) wood pulp proportioning: 100% import recycled pulp (reel wood pulp).

2. Preparing slurry for the surface layer, the core layer and the bottom layer:

(1) surface layer: the wood pulp is completely added in the surface layer, the proportion of the wood pulp in the surface layer is 30-60%, and the proportion of the fiber in the domestic OCC is 40-70%.

8. The properties of the slurry are as follows:

9. The paper index test results of the recycled kraft paper are shown in table 16.

Table 16 paper index test result table of recycled craft paper

The results in Table 16 show that the consumption of the reel instead of wood pulp is 105-112 kg/t, the unit consumption of the surface sizing starch is 33-45 kg/t, and the unit consumption of the dry strength agent is 17-24 kg/t. The indexes of the finished paper, such as breaking resistance, folding resistance and color value, all reach A2 Taka standards.

The results in tables 7 to 16 are comprehensively analyzed, and it is understood that the finished papers of the kraft cards produced in examples 4 to 13 all meet the quality index requirement of A2 kraft card. Comprehensive investigation shows that the production ration is 95-130 g/cm²When the A2 kraft liner is used, the kraft liner finished paper produced by the No. 4 and the No. 5 is qualified in quality and has obvious advantages in cost; the 5# production process saves more electricity, has advantages of raw material and power cost, has qualified indexes and lower consumption of chemical auxiliary materials, and is an optimal process. The production ration is 140-210 g/cm²The A2 Taka product has the advantages of high cost, stable paper color and good printing performance (ink absorbability), and is a preferred process.

95-130 g/cm is produced by adopting 5# production process²The A2 craft can save electricity about 65-70 kwh/t ton paper, steam about 0.08-0.1 t/t paper and waste paper raw material about 0.03-0.035 t/t paper. The yield of the paper machine is 45 ten thousand tons per year, the electricity consumption per year is 2700-3100 ten thousand degrees, the steam per year is 3.6-4.5 ten thousand tons, the raw materials are saved by 1.3-1.5 ten thousand tons, and the energy is saved and the consumption is reducedThe benefit is obvious.

140-210 g/cm is produced by adopting a 9# production process²The A2 craft can save electricity about 60-65 kwh/t ton paper, steam about 0.08-0.1 t/t ton paper and waste paper raw material about 0.04-0.045 t/t paper. The paper machine output is 65 ten thousand tons/year, 3900-4200 ten thousand degrees/year can be saved, 5.2-6.5 ten thousand tons/year of steam can be saved, and 2.6-2.9 ten thousand tons/year of raw materials can be saved.

The preparation method of the recycled craft paper provided by the invention can produce 95-210 g/cm by only using national wastes A grade and BC grade without using American wastes and European wastes²The A2 craft paper is tough and stable in quality, and solves the problem that the domestic waste OCC is used as a main raw material after the national banned import waste paper is produced, so that 95-210 g/cm with the same quality is difficult to produce²A2 production problems of the ox card. The used recycled domestic OCC waste paper accounts for 95 percent of all raw materials, meets the requirement of green recycling economic production, has good social and economic benefits, and can be popularized and applied in the field.

It should be noted that, although the above embodiments have been described herein, the invention is not limited thereto. Therefore, based on the innovative concepts of the present invention, the technical solutions of the present invention can be directly or indirectly applied to other related technical fields by making changes and modifications to the embodiments described herein, or by using equivalent structures or equivalent processes performed in the content of the present specification and the attached drawings, which are included in the scope of the present invention.

Claims

1. The utility model provides a regeneration craft paper, includes surface course, sandwich layer and bottom, its characterized in that, regeneration craft paper is made by the thick liquids of following weight percent: 80 to 95 percent of domestic OCC pulp and 5 to 20 percent of wood pulp;

the recycled craft paperThe quantitative ratio is 95-210 g/cm²。

2. The recycled craft paper of claim 1, wherein the wood pulp comprises, in weight percent, 10% to 20% unbleached eucalyptus pulp and 80% to 90% log pulp, or

3. The recycled craft paper according to claim 1, wherein the basis weight of the recycled craft paper is 95-130 g/cm²The wood pulp is unbleached softwood pulp or unbleached eucalyptus pulp;

the sizing agent of the surface layer comprises 35-50% of wood pulp and 50-65% of domestic waste OCC medium fiber;

4. The recycled craft paper according to claim 1, wherein the basis weight of the recycled craft paper is 95-130 g/cm²The wood pulp is roll wood pulp, or the wood pulp comprises 10-20% of unbleached eucalyptus pulp and 80-90% of roll wood pulp, or the wood pulp comprises 10% of unbleached softwood pulp, 20-50% of unbleached eucalyptus pulp and 40-70% of roll wood pulp;

the pulp of the surface layer comprises 25-35% of first wood pulp and 65-75% of domestic waste OCC medium fiber pulp, wherein the first wood pulp comprises 40-50% of components of reel-substitute wood pulp in the wood pulp and other types of pulp components remained in the wood pulp;

5. The recycled craft paper according to claim 1, wherein the basis weight of the recycled craft paper is 140-210 g/cm²；

6. The recycled craft paper of claim 5, wherein the face stock comprises 30-60% wood pulp and 40-70% domestic waste OCC medium fiber pulp.

7. A method for preparing recycled craft paper, which is the recycled craft paper of any one of claims 1 to 6, and the method comprises the following steps:

s10, preparing domestic waste OCC slurry:

8. The method according to claim 7, wherein the heavy-weight deslagging in steps S102, S103 and S104 is performed by a low-concentration heavy-weight deslagging device, and the low-concentration heavy-weight deslagging device is provided with a slurry economizer.

9. The method according to claim 7, wherein the step S102 between the fine screen and the multi-disk concentration further comprises the steps of:

10. The method of claim 7, wherein in the wood pulp: