阅读说明：本技术 一种灰纸板的配浆方法 (Pulp mixing method of grey paperboard ) 是由 李文宾 耿勇 刘源 张辉通 张世忠 夏瑜 陈欢欢 于 2021-08-23 设计创作，主要内容包括：本发明涉及造纸技术领域,具体为一种灰纸板的配浆方法；采用本发明提供的浆料制备的灰纸板成品不仅能有效地提高其松厚度,也进一步地改善了其耐折耐破度及其他力学性能；有效地提高了其品质；同时,其所制备的灰纸板不仅光滑平整度好,不易变形的优点；同时还具有挺度好,耐弯折等特点,有效地保证了灰纸板的质量；本发明中以废旧国产箱板纸、废旧报纸、废木纤维原材料及造纸污泥作为制备灰纸板浆料的原料,不仅改善了浆料层间结合强度,节约了纤维使用量,实现了对废旧资源的再利用；不仅节约了生产成本,也保护了环境,实现了绿色环保生产。(The invention relates to the technical field of papermaking, in particular to a pulp mixing method of a gray paperboard; the gray paperboard finished product prepared by the slurry provided by the invention not only can effectively improve the bulk, but also further improves the folding resistance, breakage resistance and other mechanical properties; the quality of the product is effectively improved; meanwhile, the prepared gray paperboard has the advantages of good smoothness and flatness and difficult deformation; meanwhile, the gray paperboard has the characteristics of good stiffness, bending resistance and the like, and the quality of the gray paperboard is effectively ensured; according to the invention, the waste domestic cardboard paper, the waste newspaper, the waste wood fiber raw material and the papermaking sludge are used as the raw materials for preparing the grey board pulp, so that the bonding strength between pulp layers is improved, the fiber usage amount is saved, and the waste resources are recycled; not only saves the production cost, but also protects the environment and realizes green and environment-friendly production.)

1. A pulp mixing method of grey boards is characterized by comprising the following steps:

step one, pulping;

i, sequentially performing processes of disintegrating, deslagging, screening, concentrating, fine sizing and storing on waste domestic cardboard paper recycled in the market, and marking the finally prepared sizing agent as a first sizing agent;

II, sequentially carrying out processes of crushing, deslagging, screening, concentrating, thermally dispersing and storing pulp on waste newspaper recycled from the market, and finally recording the obtained pulp as a second pulp;

III, sequentially carrying out chipping and crushing, metal removal, steam cooking, defibering by a defibering grinder, latency elimination and concentration regulation, heavy impurity removal, screening and concentration and high-concentration pulping on the waste wood fiber raw material, and recording the obtained pulp as third pulp;

IV, concentrating the concentration of the paper-making sludge to 2.5-3.5% by a pre-concentrator, and then conveying the concentrated paper-making sludge to a high-concentration slag remover for deslagging; carrying out coarse screening treatment on the obtained papermaking sludge with the concentration of 2-2.5%; then adding a proper amount of compound retention aid, inorganic filler and sludge wrapping agent into the mixture respectively, and mechanically mixing the mixture uniformly to obtain papermaking sludge slurry;

step two, slurry preparation;

after the second slurry obtained above is subjected to thickening by a surface layer mixing tank and a surface layer pre-papermaking tank, the second slurry is sent to a surface layer approach part for dilution and screen screening before a net, and a surface layer pulp flowing box is removed for pulp distribution and net surfing; using the obtained product as a grey board surface layer slurry; wherein the surface layer slurry of the grey board accounts for 20% of the total slurry amount;

mixing the components in a weight ratio of 1: pumping the first slurry and the third slurry of 1.3-1.8 to a lining layer mixing tank and a pre-papermaking tank for mixing and thickening; then the obtained pulp is pumped to a lining layer approach part for dilution and screening before net, and a pulp distribution and net surfing are carried out on a pulp flowing box of a paper machine; using it as a liner slurry for a grey board; wherein the grey board lining slurry accounts for 20% of the total slurry amount;

mixing the first slurry, the third slurry and the papermaking sludge slurry according to the weight ratio of 1: 1.2-1.5: pumping 0.6-0.9 of the slurry to a core layer mixing tank, mixing and thickening in a pre-papermaking tank, and feeding the slurry after mixing and thickening to a core layer feeding part for dilution and screening before screening; pulp distribution and wire laying of a paper machine lining layer pulp flowing box are carried out, and the pulp is used as grey paperboard core pulp; wherein the ash paperboard core pulp accounts for 40% of the total pulp;

mixing the first slurry and the third slurry according to the weight ratio of 1: 1-1.5 pumping a bottom layer mixing tank and a pre-papermaking tank for mixing and thickening, sending the slurry after mixing and thickening to a bottom layer approach part for dilution and screening in front of a net, removing the paper machine lining pulp flowing box and distributing the slurry to net, and taking the slurry as the bottom layer slurry of a grey board; wherein the bottom layer slurry of the grey board accounts for 20 percent of the total slurry.

2. The pulp mixing method of the grey board according to claim 1, wherein the compound retention aid used in the step IV is prepared from an inorganic retention aid and an organic retention aid according to a mass ratio of 1.5-2.0: 1, mixing and preparing; and the dosage of the compound retention aid is 0.3-0.5 kg/t of papermaking sludge.

3. A method of making a grey board according to claim 2, characterized in that the inorganic retention aid is prepared by: immersing the zeolite micro powder in the mixed solution for 2-4 h; then filtering out the zeolite micro powder, and washing the zeolite micro powder by using deionized water; then, a centrifuge is adopted to carry out centrifugal treatment on the supernatant, the supernatant is poured out, and the washing is repeated until the supernatant is checked by a sodium chloride solution and no white precipitate is generated; and drying and grinding the washed zeolite micro powder to 500-700 meshes to obtain the finished product of the inorganic retention aid.

4. A method of proportioning grey boards according to claim 3, characterised in that: the particle size of the zeolite micro powder is 80-150 meshes, and the dosage ratio of the zeolite micro powder to the mixed solution is 0.06-0.12 g/mL.

5. A method of preparing a grey board according to claim 3, wherein the method of preparing the mixed solution is: adding 6-10% of 2-methyl-4-isothiazoline-3-ketone into a silver nitrate solution with the concentration of 0.15-0.32 mol/L, and mixing and stirring uniformly to obtain a mixed solution finished product.

6. A method of proportioning grey boards according to claim 3, characterised in that: the centrifugal rate of the centrifugal machine is set to 3000-4000 r/min, and the centrifugal processing time is set to 20-30 min.

7. A method of making up grey board according to claim 2, characterised in that: the organic retention aid is selected from any one of polyacrylamide and cationic starch.

8. A method of making up grey board according to claim 1, characterised in that: the inorganic filler is prepared from calcite powder and moso bamboo powder according to a mass ratio of 1: 2-3, mixing and preparing; the particle sizes of the calcite powder and the moso bamboo powder are both 400-500 meshes; and the amount of the inorganic filler is 8-10% of that of the papermaking sludge.

9. A method of making up grey board according to claim 1, characterised in that: the amount of the sludge wrapping agent is 0.35-0.48% of that of the papermaking sludge; and the sludge wrapping agent is any one of a sludge wrapping agent CHAMPRO-AP1080 and a sludge wrapping agent JHWB-1319.

10. A method of proportioning grey boards according to claim 3, characterised in that: the temperature of the mixed solution is 65-80 ℃, and the pH value of the mixed solution is adjusted to 6.5-7.8.

Technical Field

The invention relates to the technical field of papermaking, in particular to a pulp mixing method of a gray paperboard.

Background

In recent years, with the rapid development of economy in China, the circulation of various commodities is more and more, and the demand for papermaking products keeps increasing by two digits every year. The gray paperboard is an industrial thick paperboard which is used as a base material for making products such as book covers, gift boxes, wine, cosmetic product commodity packaging boxes and the like in the packaging and printing industries.

The grey paper board has the characteristics of higher thickness, smaller tightness, lower quality requirement on raw materials, use of waste paper, semi-bleaching pulp, semi-chemical pulp and the like. So it is favored by the field of commodity packing boxes. And the demand for cardboard in the field of commodity packaging is on the trend of increasing year by year. In the process of producing the grey board, pulp preparation is an indispensable intermediate stage. When the slurry prepared by the existing process is used for preparing a gray paperboard product, although the slurry can meet the requirements of the field of commodity packaging, the smoothness and the flatness of the slurry are relatively poor, and the mechanical property of the slurry needs to be further improved, so that the quality and the sale of the gray paperboard are influenced to a certain extent.

Therefore, it is an urgent technical problem to be solved by those skilled in the art to provide a method for preparing a size of a gray paperboard.

Disclosure of Invention

The invention aims to provide a method for preparing gray paperboard, which adopts the slurry provided by the invention as a raw material for preparing the gray paperboard, and the prepared gray paperboard not only has good bulk, but also has the characteristics of good smoothness and flatness, excellent stiffness, good bending resistance and excellent mechanical property. In addition, the raw materials of the waste domestic cardboard paper, the waste newspaper, the waste wood fiber and the paper sludge are used as the raw materials for preparing the grey board pulp, so that the bonding strength between pulp layers is improved, the fiber usage amount is saved, and the waste resources are recycled; not only saves the production cost, but also protects the environment and realizes green and environment-friendly production.

In order to achieve the purpose, the invention provides the following technical scheme:

a pulp mixing method of grey boards comprises the following steps:

step one, pulping;

i, sequentially performing processes of disintegrating, deslagging, screening, concentrating, fine sizing and storing on waste domestic cardboard paper recycled in the market, and marking the finally prepared sizing agent as a first sizing agent;

II, sequentially carrying out processes of crushing, deslagging, screening, concentrating, thermally dispersing and storing pulp on waste newspaper recycled from the market, and finally recording the obtained pulp as a second pulp;

III, sequentially carrying out chipping and crushing, metal removal, steam cooking, defibering by a defibering grinder, latency elimination and concentration regulation, heavy impurity removal, screening and concentration and high-concentration pulping on the waste wood fiber raw material, and recording the obtained pulp as third pulp;

IV, concentrating the concentration of the paper-making sludge to 2.5-3.5% by a pre-concentrator, and then conveying the concentrated paper-making sludge to a high-concentration slag remover for deslagging; carrying out coarse screening treatment on the obtained papermaking sludge with the concentration of 2-2.5%; then adding a proper amount of compound retention aid, inorganic filler and sludge wrapping agent into the mixture respectively, and mechanically mixing the mixture uniformly to obtain papermaking sludge slurry;

step two, slurry preparation;

after the second slurry obtained above is subjected to thickening by a surface layer mixing tank and a surface layer pre-papermaking tank, the second slurry is sent to a surface layer approach part for dilution and screen screening before a net, and a surface layer pulp flowing box is removed for pulp distribution and net surfing; using the obtained product as a grey board surface layer slurry; wherein the surface layer slurry of the grey board accounts for 20% of the total slurry amount;

mixing the components in a weight ratio of 1: pumping the first slurry and the third slurry of 1.3-1.8 to a lining layer mixing tank and a pre-papermaking tank for mixing and thickening; then the obtained pulp is pumped to a lining layer approach part for dilution and screening before net, and a pulp distribution and net surfing are carried out on a pulp flowing box of a paper machine; using it as a liner slurry for a grey board; wherein the grey board lining slurry accounts for 20% of the total slurry amount;

mixing the first slurry, the third slurry and the papermaking sludge slurry according to the weight ratio of 1: 1.2-1.5: pumping 0.6-0.9 of the slurry to a core layer mixing tank, mixing and thickening in a pre-papermaking tank, and feeding the slurry after mixing and thickening to a core layer feeding part for dilution and screening before screening; pulp distribution and wire laying of a paper machine lining layer pulp flowing box are carried out, and the pulp is used as grey paperboard core pulp; wherein the ash paperboard core pulp accounts for 40% of the total pulp;

mixing the first slurry and the third slurry according to the weight ratio of 1: 1-1.5 pumping a bottom layer mixing tank and a pre-papermaking tank for mixing and thickening, sending the slurry after mixing and thickening to a bottom layer approach part for dilution and screening in front of a net, removing the paper machine lining pulp flowing box and distributing the slurry to net, and taking the slurry as the bottom layer slurry of a grey board; wherein the bottom layer slurry of the grey board accounts for 20 percent of the total slurry.

Furthermore, the compound retention aid used in the step IV is prepared from an inorganic retention aid and an organic retention aid according to a mass ratio of 1.5-2.0: 1, mixing and preparing; and the dosage of the compound retention aid is 0.3-0.5 kg/t of papermaking sludge.

Further, the preparation method of the inorganic retention aid comprises the following steps: immersing the zeolite micro powder in the mixed solution for 2-4 h; then filtering out the zeolite micro powder, and washing the zeolite micro powder by using deionized water; then, a centrifuge is adopted to carry out centrifugal treatment on the supernatant, the supernatant is poured out, and the washing is repeated until the supernatant is checked by a sodium chloride solution and no white precipitate is generated; and drying and grinding the washed zeolite micro powder to 500-700 meshes to obtain the finished product of the inorganic retention aid.

Furthermore, the particle size of the zeolite micro powder is 80-150 meshes, and the dosage ratio of the zeolite micro powder to the mixed solution is 0.06-0.12 g/mL.

Further, the preparation method of the mixed solution comprises the following steps: adding 6-10% of 2-methyl-4-isothiazoline-3-ketone into a silver nitrate solution with the concentration of 0.15-0.32 mol/L, and mixing and stirring uniformly to obtain a mixed solution finished product.

Furthermore, the centrifugal rate of the centrifugal machine is set to be 3000-4000 r/min, and the time of centrifugal treatment is set to be 20-30 min.

Furthermore, the organic retention aid is selected from any one of polyacrylamide and cationic starch.

Furthermore, the inorganic filler is prepared from calcite powder and moso bamboo powder according to a mass ratio of 1: 2-3, mixing and preparing; the particle sizes of the calcite powder and the moso bamboo powder are both 400-500 meshes; and the amount of the inorganic filler is 8-10% of that of the papermaking sludge.

Furthermore, the amount of the sludge wrapping agent is 0.35-0.48% of that of the papermaking sludge; and the sludge wrapping agent is any one of a sludge wrapping agent CHAMPRO-AP1080 and a sludge wrapping agent JHWB-1319.

Furthermore, the temperature of the mixed solution is 65-80 ℃, and the pH value of the mixed solution is adjusted to 6.5-7.8.

Compared with the prior art, the invention has the beneficial effects that:

1. according to the invention, the waste domestic cardboard paper, the waste newspaper, the waste wood fiber raw material and the papermaking sludge are used as the raw materials for preparing the grey board pulp, so that the bonding strength between pulp layers is improved, the fiber usage amount is saved, and the waste resources are recycled; not only saves the production cost, but also protects the environment and realizes green and environment-friendly production. Moreover, the gray paperboard finished product prepared by the slurry provided by the invention not only can effectively improve the bulk, but also further improves the folding resistance, the bursting strength and other mechanical properties; effectively improving the quality of the product.

2. The invention takes zeolite micro powder, silver nitrate and 2-methyl-4-isothiazoline-3-ketone as raw materials for preparing an inorganic retention aid, and the raw materials and the organic retention aid are compatible with each other to prepare a compound retention aid. The obtained compound retention aid, inorganic fillers (calcite powder and moso bamboo powder) and the sludge wrapping agent are used as raw materials of the prepared grey paperboard slurry together, so that the interaction between the papermaking sludge and fiber components in the slurry is facilitated, the distribution characteristic of the papermaking sludge in a paper web network structure is effectively adjusted, and the bonding strength of a hydrogen bond structure is enhanced. Moreover, the prepared gray paperboard has the advantages of good smoothness and flatness and difficult deformation. Meanwhile, the gray paperboard has the characteristics of good stiffness, bending resistance and the like, and the quality of the gray paperboard is effectively ensured.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

A pulp mixing method of grey boards comprises the following steps:

step one, pulping;

i, sequentially performing processes of disintegrating, deslagging, screening, concentrating, fine sizing and storing on waste domestic cardboard paper recycled in the market, and marking the finally prepared sizing agent as a first sizing agent;

II, sequentially carrying out processes of crushing, deslagging, screening, concentrating, thermally dispersing and storing pulp on waste newspaper recycled from the market, and finally recording the obtained pulp as a second pulp;

III, sequentially carrying out chipping and crushing, metal removal, steam cooking, defibering by a defibering grinder, latency elimination and concentration regulation, heavy impurity removal, screening and concentration and high-concentration pulping on the waste wood fiber raw material, and recording the obtained pulp as third pulp;

IV, concentrating the concentration of the paper-making sludge to 2.5% by a pre-concentrator, and then conveying the concentrated paper-making sludge to a high-concentration slag remover for deslagging; the obtained papermaking sludge with the concentration of 2% is subjected to coarse screening treatment; then adding a proper amount of compound retention aid, inorganic filler and sludge wrapping agent into the mixture respectively, and mechanically mixing the mixture uniformly to obtain papermaking sludge slurry;

step two, slurry preparation;

after the second slurry obtained above is subjected to thickening by a surface layer mixing tank and a surface layer pre-papermaking tank, the second slurry is sent to a surface layer approach part for dilution and screen screening before a net, and a surface layer pulp flowing box is removed for pulp distribution and net surfing; using the obtained product as a grey board surface layer slurry; wherein the surface layer slurry of the grey board accounts for 20 percent of the total slurry;

mixing the components in a weight ratio of 1: 1.3, pumping the first slurry and the third slurry to a lining mixing tank and a pre-papermaking tank for mixing and thickening; then the obtained pulp is pumped to a lining layer approach part for dilution and screening before net, and a pulp distribution and net surfing are carried out on a pulp flowing box of a paper machine; using it as a liner slurry for a grey board; wherein the grey board lining slurry accounts for 20% of the total slurry amount;

mixing the first slurry, the third slurry and the papermaking sludge slurry according to the weight ratio of 1: 1.2: 0.6, pumping to a core layer mixing tank and a pre-papermaking tank for mixing and thickening, and sending the slurry after mixing and thickening to a core layer flow feeding part for dilution and screening before a screen; pulp distribution and wire laying of a paper machine lining layer pulp flowing box are carried out, and the pulp is used as grey paperboard core pulp; wherein the ash paperboard core pulp accounts for 40% of the total pulp;

mixing the first slurry and the third slurry according to the weight ratio of 1: 1, pumping a bottom layer mixing tank and a pre-papermaking tank for mixing and thickening, sending the mixed and thickened pulp to a bottom layer approach part for dilution and screen-in-front, removing pulp from a pulp flowing box of a paper machine lining, and spreading pulp on a net to obtain the pulp as the bottom pulp of a grey board; wherein, the bottom layer slurry of the grey board accounts for 20 percent of the total amount of the slurry.

The compound retention aid used in the step IV is prepared from an inorganic retention aid and an organic retention aid according to a mass ratio of 1.5: 1, mixing and preparing; and the dosage of the compound retention aid is 0.3kg/t of paper sludge.

The preparation method of the inorganic retention aid comprises the following steps: immersing the zeolite micro powder in the mixed solution for 2 hours; then filtering out the zeolite micro powder, and washing the zeolite micro powder by using deionized water; then, a centrifuge is adopted to carry out centrifugal treatment on the supernatant, the supernatant is poured out, and the washing is repeated until the supernatant is checked by a sodium chloride solution and no white precipitate is generated; and drying and grinding the washed zeolite micropowder to 500 meshes to obtain the finished product of the inorganic retention aid.

The particle size of the zeolite micro powder is 80 meshes, and the dosage ratio of the zeolite micro powder to the mixed solution is 0.06 g/mL.

The preparation method of the mixed solution comprises the following steps: adding 6% of 2-methyl-4-isothiazoline-3-ketone into 0.15mol/L silver nitrate solution, and mixing and stirring uniformly to obtain a mixed solution finished product.

The centrifuge rate of the centrifuge was set to 3000r/min, and the time for the centrifugation treatment was set to 20 min.

The organic retention aid is selected from polyacrylamide.

The inorganic filler is prepared from calcite powder and moso bamboo powder according to a mass ratio of 1: 2, mixing and preparing; the particle sizes of the calcite powder and the moso bamboo powder are both 400 meshes; and the dosage of the inorganic filler is 8 percent of the papermaking sludge.

The amount of the sludge wrapping agent is 0.35 percent of that of the papermaking sludge; and the sludge wrapping agent is CHAMPRO-AP 1080.

The temperature of the mixed solution was 65 ℃ and the pH thereof was adjusted to 6.5.

Example 2

The main differences between this example and example 1 are:

in the liner slurry of the grey board, the weight ratio of the first slurry to the third slurry is 1: 1.5;

in the grey paperboard core pulp, the weight ratio of the first pulp to the third pulp to the papermaking sludge pulp is 1: 1.4: 0.8;

in the bottom layer slurry of the grey paperboard, the first slurry and the third slurry are mixed according to the weight ratio of 1: 1.3.

the compound retention aid used in the step IV is prepared from an inorganic retention aid and an organic retention aid according to a mass ratio of 1.8: 1, mixing and preparing; and the dosage of the compound retention aid is 0.4kg/t of paper sludge.

The preparation method of the inorganic retention aid comprises the following steps: immersing the zeolite micro powder in the mixed solution for 3 hours; then filtering out the zeolite micro powder, and washing the zeolite micro powder by using deionized water; then, a centrifuge is adopted to carry out centrifugal treatment on the supernatant, the supernatant is poured out, and the washing is repeated until the supernatant is checked by a sodium chloride solution and no white precipitate is generated; and drying and grinding the washed zeolite micropowder to 600 meshes to obtain the finished product of the inorganic retention aid.

The particle size of the zeolite micropowder is 100 meshes, and the dosage ratio of the zeolite micropowder to the mixed solution is 0.1 g/mL.

The preparation method of the mixed solution comprises the following steps: adding 8% by mass of 2-methyl-4-isothiazoline-3-ketone into 0.25mol/L silver nitrate solution, and mixing and stirring uniformly to obtain a mixed solution finished product.

The centrifuge rate was set at 3500r/min and the time of the centrifugation was set at 25 min.

The organic retention aid is cationic starch.

The inorganic filler is prepared from calcite powder and moso bamboo powder according to a mass ratio of 1: 2.5 mixing and preparing; the particle sizes of the calcite powder and the moso bamboo powder are both 450 meshes; and the dosage of the inorganic filler is 9 percent of the papermaking sludge.

The amount of the sludge wrapping agent is 0.42 percent of that of the papermaking sludge; and the sludge wrapping agent is JHWB-1319.

The temperature of the mixed solution was 75 ℃ and the pH thereof was adjusted to 7.2.

Example 3

The main differences between this example and example 1 are:

in the liner slurry of the grey board, the weight ratio of the first slurry to the third slurry is 1: 1.8;

in the grey paperboard core pulp, the weight ratio of the first pulp to the third pulp to the papermaking sludge pulp is 1: 1.5: 0.9;

in the bottom layer slurry of the grey paperboard, the first slurry and the third slurry are mixed according to the weight ratio of 1: 1.5.

the compound retention aid used in the step IV is prepared from an inorganic retention aid and an organic retention aid according to the mass ratio of 2.0: 1, mixing and preparing; and the dosage of the compound retention aid is 0.5kg/t of paper sludge.

The preparation method of the inorganic retention aid comprises the following steps: immersing the zeolite micro powder in the mixed solution for 4 hours; then filtering out the zeolite micro powder, and washing the zeolite micro powder by using deionized water; then, a centrifuge is adopted to carry out centrifugal treatment on the supernatant, the supernatant is poured out, and the washing is repeated until the supernatant is checked by a sodium chloride solution and no white precipitate is generated; and drying and grinding the washed zeolite micropowder to 700 meshes to obtain the finished product of the inorganic retention aid.

The particle size of the zeolite micropowder was 150 mesh, and the amount ratio thereof to the mixed solution was 0.12 g/mL.

The preparation method of the mixed solution comprises the following steps: adding 10% by mass of 2-methyl-4-isothiazoline-3-ketone into 0.32mol/L silver nitrate solution, and mixing and stirring uniformly to obtain a mixed solution finished product.

The centrifuge rate of the centrifuge was set to 4000r/min, and the time for the centrifugation was set to 30 min.

The organic retention aid is selected from any one of polyacrylamide and cationic starch.

The inorganic filler is prepared from calcite powder and moso bamboo powder according to a mass ratio of 1: 3, mixing and preparing; the particle sizes of the calcite powder and the moso bamboo powder are both 500 meshes; and the dosage of the inorganic filler is 10 percent of the papermaking sludge.

The amount of the sludge wrapping agent is 0.48 percent of that of the papermaking sludge; and the sludge wrapping agent is CHAMPRO-AP 1080.

The temperature of the mixed solution was 80 ℃ and the pH thereof was adjusted to 7.8.

Comparative example 1: the main differences between this embodiment and embodiment 1 are: common zeolite with the same amount and similar size is selected to replace an inorganic retention aid;

comparative example 2: the main differences between this embodiment and embodiment 1 are: the inorganic filler only adopts calcite powder;

comparative example 3: the main differences between this embodiment and embodiment 1 are: the inorganic filler only selects moso bamboo powder;

performance testing

The gray paperboards produced by the examples 1 to 3 of the invention are referred to as experimental examples 1 to 3; the gray paperboards produced in the comparative examples 1-3 are marked as comparative examples; then, the grey paper boards provided in the experimental examples 1 to 3 and the comparative examples 1 to 3 are respectively subjected to related performance tests, and the obtained data are recorded in the following table:

as can be seen from the relevant data in the table, the prepared gray paperboard not only has good bulk, but also has the characteristics of good smoothness and flatness, excellent stiffness, good bending resistance and excellent mechanical property by using the slurry provided by the invention as a raw material for preparing the gray paperboard. In addition, the invention takes the waste domestic cardboard paper, the waste newspaper, the waste wood fiber raw material and the paper sludge as the raw materials for preparing the grey board pulp, thereby not only improving the interlayer bonding strength of the pulp, saving the fiber usage amount and realizing the reutilization of waste resources. Not only saves the production cost, but also protects the environment and realizes green and environment-friendly production. Therefore, the gray paperboard product produced by the invention has wider market prospect and is more suitable for popularization.

In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The preferred embodiments of the invention disclosed above are intended to be illustrative only. The preferred embodiments are not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention. The invention is limited only by the claims and their full scope and equivalents.