CN110295508B

CN110295508B - Method for treating waste paper with low lignin content, low transition metal content and high wet strength

Info

Publication number: CN110295508B
Application number: CN201910588657.7A
Authority: CN
Inventors: 陈传勇; 施彩莲; 陈欢欢; 童含信; 吴飞燕; 施德新
Original assignee: Zhejiang Jinlong Renewable Resources Technology Co Ltd
Current assignee: Zhejiang Jinlong Renewable Resources Technology Co Ltd
Priority date: 2019-07-02
Filing date: 2019-07-02
Publication date: 2020-08-04
Anticipated expiration: 2039-07-02
Also published as: CN110295508A

Abstract

The invention provides a method for treating waste paper with low lignin content and low transition metal content and high wet strength, and particularly relates to OCC pulp prepared from the waste paper and coated white board prepared from the OCC pulp. Specifically, the coated white board comprises a surface layer, a lining layer, a core layer and a bottom layer, wherein the lining layer is made of OCC pulp. The invention utilizes OCC pulp to prepare high-grade coated white board paper, and has low cost and simple production process. Meanwhile, the OCC pulp is modified by enzyme and added with cationic polymer, the physical properties of the white board paper are greatly improved compared with those of a single modification mode, the optimal enzyme treatment time, concentration and addition amount of the cationic polymer are found out through experiments, the physical properties of the paper are further improved in a synergistic manner, excellent effects are obtained, and the white board paper has good market prospects.

Description

Method for treating waste paper with low lignin content, low transition metal content and high wet strength

Technical Field

The invention relates to the technical field of pulping and papermaking, in particular to a method for treating high-wet-strength waste paper with low lignin content and low transition metal content, and specifically relates to OCC pulp prepared from the waste paper and coated white board paper prepared from the OCC pulp.

Background

The white board paper is coated with a layer of coating which has good ink absorbability on the surface of paper so as to obtain paper with good uniformity and smoothness, and meanwhile, the whiteness and the glossiness of the paper are improved, and the ink absorbability and the opacity of the paper are improved, so that the printability of the paper is improved, the printing effect is improved, and the defects of the base paper are overcome. The coating is prepared by taking white pigments such as kaolin, calcium carbonate, barium sulfate, titanium dioxide and the like as main bodies, adding various adhesives and various chemical auxiliary agents according to requirements, uniformly coating the main bodies on the surface of paper or paperboard according to a certain amount, and forming the coated white paperboard meeting various requirements through finishing processing.

The white board generally comprises a surface layer, a lining layer, a core layer and a bottom layer, wherein the first layer is surface layer pulp, is required to have high whiteness and certain strength, and usually adopts bleached sulfate wood pulp or is added with partial bleached chemical straw pulp and white paper edge waste paper pulp; the second layer is a lining layer, and also needs to have certain whiteness, and 100 percent mechanical wood pulp or light-colored waste paper pulp is usually used; the third layer is a core layer which mainly plays a filling role to increase the thickness of the paperboard, the mixed waste paper pulp or straw pulp is generally adopted, the last layer is a bottom layer which has the advantages of improving the appearance of the paperboard and improving the strength, high-yield pulp or better waste paper pulp is generally used as a raw material for papermaking, the bottom color of the paperboard is multi-gray, and other bottom colors can also be produced according to requirements.

The quality of coated white board Paper is closely related to the quality of base Paper, the raw materials for producing the base Paper of the coated white board Paper are various, most of the raw materials used for producing the coated white board Paper in China are wood pulp raw materials, the price of the wood pulp is continuously increased along with the shortage of wood resources, and a plurality of enterprises have to find waste Paper raw materials which are cheaper and can ensure the product quality, for example, imported ONP (Old News Paper) such as No. 3 American waste, No. 6 American waste, No. 8 American waste, No. 9 American waste and OMG (Old Magazine) are used as pulp raw materials of a bottom layer or a core layer, but the production of ONP pulp has large water and electricity consumption, the consumption of deinking chemical auxiliary materials, more slag and water discharge, high waste water environmental protection treatment cost and high ONP pulp comprehensive cost. To solve this problem, OCC pulp (Old Corrugated Container) which is cheaper to prepare is generally used as a substitute in the prior art. However, the raw material of the cardboard paper is usually prepared from recycled waste paper, the recycling frequency of the waste paper is increased, the fiber swelling is difficult, the strength is reduced, the drainage performance is reduced, the fiber bonding strength is reduced due to fiber keratinization, the pulping and papermaking production is seriously influenced, and the industrial requirements cannot be met.

In order to increase the fiber strength of recycled waste paper, such as OCC pulp, the prior art has generally used dry strength additives, which are typically water-soluble, hydrophilic natural or synthetic polymers. Commonly used dry strength agents are Cationic Starch (CS) and polyvinyl alcohol (PVA). The dry strength agent can interact with the fibers in various ways to improve the bonding strength. However, the dry strength agent is used for improving the fiber strength of the OCC pulp, so that the problems of complex process and high cost exist, or the improvement degree of the fiber strength of the OCC pulp is limited, and the requirement of industrial production of high-quality white board paper is difficult to meet.

Therefore, the method for improving the strength of the fibers in the OCC pulp with simple process and low cost to produce high-quality coated white board paper is a problem which is urgently needed to be solved in the field.

Disclosure of Invention

The invention provides coated white board paper and a preparation method thereof, aiming at solving the problems that the process is complex, the cost is high, the fiber strength of the produced white board paper is not high, and the market requirements on high-grade white board paper are difficult to meet and the like in the prior art of producing the coated white board paper by utilizing recycled waste paper such as OCC pulp.

In one embodiment, the present invention provides a coated white board, the liner being made from an OCC pulp treated with cellulase and ligninase, and having added thereto a cationic polymer P (St-BA-AA-GMA), the cellulase being present in an amount of 50-100IU/g, the ligninase being present in an amount of 20-40IU/g, and the P (St-BA-AA-GMA) being present in an amount of 0.5-2%.

The OCC pulp is prepared by using waste paper as a raw material, preferably, the OCC pulp can be selected from waste paper with low lignin content and/or low transition metal content and high wet strength, and more preferably, the waste paper is waste corrugated paper.

In one embodiment, the cellulase and ligninase treatment is performed for a period of 60 to 120 min.

In one embodiment, the cellulase is present in an amount of 92IU/g and the ligninase is present in an amount of 33 IU/g.

In one embodiment, the cellulase and ligninase treatment is performed for 90min, and preferably, the P (St-BA-AA-GMA) is added in an amount of 1.5%.

The cellulase and ligninase may be enzymes known in the art or commercially available.

The P (St-BA-AA-GMA) is a cationic polymer, which is used for adsorption film formation on fibers in the prior art, and is used for fiber modification, paint dyeing and other applications, and cationic P (St-BA-AA-GMA) is synthesized by using styrene (St), Butyl Acrylate (BA), Acrylic Acid (AA) and Glycidyl Methacrylate (GMA) as monomers, cetyltrimethylammonium chloride (CTAC) as an emulsifier and azobisisobutylimidazole hydrochloride (AIBA) as an initiator by a semi-continuous emulsion polymerization method, and specific preparation methods can be referred to "synthesis of cationic P (St-BA-AA-GMA) emulsion and fixation effect on paint" singling, shigao-shikou thesis at university of Qingdao, 2015 ", and are adjusted accordingly, and are as follows:

introducing nitrogen, adding deionized water, a dissolved emulsifier and a sodium acetate buffer, starting a stirring device, and stirring to uniformly dissolve the emulsifier in the water; and adding St, BA and AA mixed monomers, pre-emulsifying for a certain time, heating to 80 +/-1 ℃, dropwise adding the rest GMA, BA and St mixed monomers (the dropwise adding speed is controlled to be 5 s/drop), dropwise adding a dissolved AIBA initiator, and adding a sodium acetate buffer to keep the pH value between 6 and 8. After the dropwise addition, the reaction is carried out for 3.5h at 80 ℃, the temperature is naturally reduced to 40-50 ℃, and the material is discharged, wherein the dosage of St, BA, AA and GMA is 7:11:0.2:1.8

In one embodiment, the facing of the white board pair comprises ONP and DIP pulps as facing pulps, wherein the ONP and DIP pulps are used in a ratio of 2: 1; the lining layer comprises ONP slurry and OCC slurry as lining layer slurry, wherein the using ratio of the ONP slurry to the OCC slurry is 1: 1; the bottom layer comprises ONP slurry and OCC slurry as lining slurry, wherein the ratio of the ONP slurry to the OCC slurry is 1: 3.

In one embodiment, the present invention provides a method for preparing coated white board paper, characterized by the steps of:

(1) preparing ONP slurry, DIP slurry and OCC slurry;

(2) slurry formulation for top, bottom, core and under layers

(3) Manufacturing raw paper;

(4) coating, soft calendering and coiling.

In one embodiment, in the step (1), the OCC pulp is treated by cellulase and ligninase, and cationic polymer P (St-BA-AA-GMA) is added, wherein the dosage of the cellulase is 50-100IU/g, the dosage of the ligninase is 20-40IU/g, and the dosage of the P (St-BA-AA-GMA) is 0.5-2%.

In one embodiment, in the method of preparation, the cellulase and ligninase are treated for a period of time ranging from 60 to 120 min.

In one embodiment, in the preparation method, the cellulase is used in an amount of 92IU/g, the ligninase is used in an amount of 33IU/g, preferably, the cellulase and ligninase are treated for 90min, and further preferably, the P (St-BA-AA-GMA) is added in an amount of 1.5%.

In one embodiment, the OCC slurry is prepared by the steps of:

a. using domestic waste corrugated paper as a raw material, and obtaining OCC pulp through crushing, screening, deslagging, concentrating and thermal dispersion;

b. and (2) treating the OCC pulp by using cellulase and ligninase, adjusting the concentration of the OCC pulp to 4-8 wt%, adding the cellulase and ligninase for treatment, wherein the treatment temperature is 50 ℃, the pH value is 8, the treatment time is 90min, the dosage of the cellulase is 92IU/g, and the dosage of the ligninase is 33 IU/g.

c. Adding a cationic polymer to modify the OCC slurry, wherein the cationic polymer is P (St-BA-AA-GMA), styrene (St), Butyl Acrylate (BA), Acrylic Acid (AA) and Glycidyl Methacrylate (GMA) are taken as monomers, cetyltrimethylammonium chloride (CTAC) is taken as an emulsifier, azodiisobutyl imidazole hydrochloride (AIBA) is taken as an initiator, synthesizing the cationic polymer P (St-BA-AA-GMA) by adopting a semi-continuous emulsion polymerization method, preparing the cationic polymer P (St-BA-AA-GMA) into 2 g/L emulsion, adding the emulsion into the OCC slurry treated by the cellulase and the ligninase in the step b, and stirring the emulsion at room temperature of 25 ℃ for 40min for later use, wherein the specific dosage is 1.5%.

Compared with the prior art, the invention has the following advantages: the invention utilizes OCC pulp to prepare high-grade coated white board paper, and has low cost and simple production process. Meanwhile, the physical properties of the white board paper are greatly improved compared with a single modification mode by adopting enzyme modification and adding cationic polymer modified OCC pulp, and the optimal enzyme treatment time, concentration and addition amount of the cationic polymer are found out through experiments, so that the physical properties of the paper are further improved in a synergistic manner, a good effect is obtained, and the white board paper has a good market prospect.

Detailed Description

The effects of the coated white board of the present invention will be described in detail below with reference to the preferred embodiments of the present invention, but the following description should not be construed as limiting the scope of the present invention.

Example 1 preparation of a high-grade coated white paperboard having excellent physical properties

This example provides a method for preparing a high-grade coated white paperboard with excellent physical properties by modifying the core OCC slurry

The method comprises the following specific steps:

1. preparation of various slurries:

(1) preparing ONP slurry: taking Japanese No. 3 and American waste No. 8 as raw materials, wherein the weight ratio of the Japanese No. 3 to the American waste No. 8 is 3:7, the raw materials are primarily selected by a bale breaker, are pulped into paper pulp by a drum pulper, are subjected to deslagging by a high-concentration deslagging system, are subjected to coarse screening to remove impurities, are washed by water to remove ink after being subjected to coarse screening, then enter a flotation tank for flotation, are subjected to screening by three-section fine screening and concentration, are sent to a thermal dispersion machine for thermal dispersion to disperse adhesive substances in the pulp, and the treated pulp enters a pulp tank for later use;

the ONP slurry has a freeness of 210csf, a whiteness value of 40ISO and a impurity point content of 980mm²/m²；

(2) Preparation of DIP slurry: the method comprises the steps of taking American waste 3# and American waste 8# as raw materials, enabling the weight ratio of the American waste 3# to the American waste 8# to be 1:1, conducting primary sorting on the raw materials through a bale breaker, sending the raw materials to a drum pulper to be smashed into paper pulp, conducting coarse screening to screen impurities, enabling screened good pulp to enter a slag separator to remove slag, conducting washing deinking treatment, conducting flotation treatment after two-stage fine screening, sending the flotation treatment to a thickener to be concentrated after the flotation treatment, then sending the flotation treatment to a thermal dispersion machine to conduct thermal dispersion to disperse adhesive substances in the pulp, conducting high-concentration oxidation bleaching on the pulp after the thermal dispersion treatment, enabling the pulp to enter the thickener to be concentrated after the oxidation bleaching, conducting reduction bleaching on the concentrated pulp, and enabling the pulp after the reduction bleaching treatment to enter a pulp tank for standby.

The freeness of the DIP pulp is 230csf, the whiteness value is 55ISO, and the content of impurity points is 800mm²/m²

(3) Preparing OCC slurry:

a. the method comprises the following steps of taking domestic waste corrugated paper as a raw material, primarily selecting and sorting the raw material by a bale breaker, sending the raw material to a drum pulper for pulping into paper pulp, screening impurities by a coarse screen, sending fine pulp after screening into a slag remover for slag removal, carrying out flotation treatment after two-stage fine screen screening, sending the fine pulp after flotation treatment into a thickener for concentration, then sending the fine pulp to a thermal dispersion machine for thermal dispersion to disperse hot-melt substances such as adhesive substances, oil wax and the like in the pulp, and sending the treated pulp to a pulp tank for later use; the beating degree of the OCC pulp is 48.5 DEG SR.

b. Treating OCC pulp with cellulase and ligninase, adjusting the concentration of OCC pulp to 4-8 wt%, adding cellulase and ligninase for treatment, wherein the treatment temperature is 40-60 ℃, the pH value is 6-9, the treatment time is 60-120min, the dosage of cellulase is 50-100IU/g, and the dosage of ligninase is 20-40 IU/g.

c. Adding a cationic polymer to modify OCC slurry, wherein the cationic polymer is P (St-BA-AA-GMA), styrene (St), Butyl Acrylate (BA), Acrylic Acid (AA) and Glycidyl Methacrylate (GMA) are taken as monomers, hexadecyl trimethyl ammonium chloride (CTAC) is taken as an emulsifier, azodiisobutyl imidazole hydrochloride (AIBA) is taken as an initiator, and synthesizing the cationic polymer P (St-BA-AA-GMA) by adopting a semi-continuous emulsion polymerization method, and the specific method comprises the following steps:

introducing nitrogen, adding deionized water, a dissolved emulsifier and a sodium acetate buffer, starting a stirring device, and stirring to uniformly dissolve the emulsifier in the water; and then adding mixed monomers of St, BA and AA, pre-emulsifying for a certain time, heating to 80 +/-1 ℃, dropwise adding the rest mixed monomers of GMA, BA and St (the dropwise adding speed is controlled to be 5 s/drop), dropwise adding a dissolved AIBA initiator, and adding a sodium acetate buffer to keep the pH value between 6 and 8. After the dropwise addition, reacting at 80 ℃ for 3.5h, naturally cooling to 40-50 ℃, and discharging, wherein the dosage of St, BA, AA and GMA is 7:11:0.2: 1.8;

preparing an emulsion with cationic polymer P (St-BA-AA-GMA) of 2 g/L, adding into the OCC slurry treated by cellulase and ligninase in step b, wherein the specific dosage is 0.5-2% (relative to absolute dry slurry), and stirring at room temperature of 25 ℃ for 20-60 min for later use.

2. Preparation of slurries at different levels

Preparing surface layer slurry: using the ONP slurry and the DIP slurry prepared in the steps as surface layer slurry, wherein the using ratio of the ONP slurry to the DIP slurry is 2:1, and the weight of the prepared slurry is 32.9g/m²；

Preparing lining layer slurry: the ONP slurry and the OCC slurry prepared in the steps are used as lining slurry, wherein the using ratio of the ONP slurry to the OCC slurry is 1:1, and the weight of the prepared slurry is 21.2g/m²；

Preparing core layer slurry: the OCC slurry prepared in the steps is used as core layer slurry, and the core layer slurry mixing ration is 96g/m²；

Preparing bottom layer slurry: the ONP slurry and the OCC slurry prepared in the steps are used as lining slurry, wherein the using ratio of the ONP slurry to the OCC slurry is 1:3, and the weight of the prepared slurry is 31.6g/m²；

3. Manufacturing base paper:

conveying the pulp of each layer to a pulp box of a paper machine through respective feeding systems, feeding the pulp of each layer with a certain concentration to a four-layer forming net to form a wet paper sheet, and performing paper making on the wet paper sheet through pressing, a front drying part, surface sizing and hard calendering, wherein the weight of the base paper is 410g/m²；

4. Coating, soft calendering and coiling:

conveying the coating base paper subjected to hard calendering to a curtain coater, performing curtain coating on a front sizing layer of the coating base paper to form a curtain coating, conveying the coating base paper with the curtain coating to a scraper coater to perform scraper coating to form a top coating,wherein the coating weight of the curtain coating is 11g/m²The coating weight of the top coating is 15g/m². After coating, soft press polishing, reeling, rewinding and warehousing.

Example 2 Effect of different enzyme concentrations on physical Properties of white board paper

In order to investigate the influence of different enzyme concentrations on the physical properties of white board paper by modified OCC pulp, and seek to find the most suitable enzyme treatment concentration, the following experimental design is adopted in this example:

in the preparation of OCC slurry, different concentrations of cellulase and ligninase were used for treatment, and the addition of cationic polymer to OCC slurry was eliminated to analyze and determine the most suitable enzyme treatment concentration, the specific enzyme concentration addition amounts are shown in Table 1,

TABLE 1 addition amounts of cellulase and ligninase in OCC slurries

The above-mentioned different concentrations, every group sets up 3 parallel experiments, the concrete step is as follows

1. Preparation of various slurries:

the ONP deinking pulp has the freeness of 210csf, the whiteness value of 40ISO and the impurity point content of 980mm²/m²；

(3) Preparing OCC slurry:

b. And (3) treating the OCC pulp by using cellulase and ligninase, adjusting the concentration of the OCC pulp to be 4-8 wt%, adding the cellulase and ligninase for treatment, wherein the treatment temperature is 50 ℃, the pH value is 8, and the treatment time is 60min, and the dosage of the cellulase and ligninase is shown in table 1.

2. Preparation of slurries at different levels

Preparing bottom layer slurry: o prepared by the above procedureNP slurry and OCC slurry are lining slurry, wherein the using ratio of ONP slurry to OCC slurry is 1:3, and the weight of the prepared slurry is 31.6g/m²；

3. Manufacturing base paper:

4. Coating, soft calendering and coiling:

conveying the coating base paper subjected to hard calendering to a curtain coater, carrying out curtain coating on a front sizing layer of the coating base paper to form a curtain coating, and conveying the coating base paper with the curtain coating to a scraper coater to carry out scraper coating to form a top coating, wherein the coating weight of the curtain coating is 11g/m²The coating weight of the top coating is 15g/m². After coating, soft press polishing, reeling, rewinding and warehousing.

5. White board paper test result

The physical properties of the white board 1-12 prepared by the method are detected, and the physical property indexes are quantification, transverse stiffness, folding endurance (transverse) bursting index, interlayer strength and ring crush index, wherein,

quantitatively detecting the coated white board according to GB/T451.2;

the bursting index of the coated white board paper is detected according to GB/T1539;

detecting the ring crush index of the coated white board according to GB/T2679.8;

measurement of folding resistance of coated white cardboard paper GB/T1539-

The interlayer strength of the coated white board paper is determined according to GB/T26203-;

the stiffness of the coated white board was determined in accordance with GB/T22364-

The physical properties of the white board prepared from OCC pulps treated with different enzyme concentrations are shown in Table 2

TABLE 2 white paperboard 1-white paperboard 12 physical Properties

As can be seen from the results shown in Table 2, the white board prepared from the OCC pulp treated with the enzyme has improved physical property parameters compared with the control group (the OCC pulp is not treated with the enzyme), which indicates that the combination treatment of the OCC pulp with the cellulase and the ligninase is beneficial to improving the physical property of the white board prepared from the OCC pulp. Further, as can be seen from the results in table 2, the physical properties of the white board paper are improved with the increase of the enzyme concentration, but when the enzyme concentration is increased to a certain amount, the physical properties of the white board paper are rather reduced by continuously increasing the enzyme concentration, and the analysis reason may be that the cellulase and the ligninase remove the fines in the OCC pulp to increase the content of the medium-long fibers, which is beneficial to improving the physical properties of the white board paper, but the medium-long fibers are also affected correspondingly with the further increase of the enzyme concentration, which is rather to reduce the physical properties of the white board paper. From the results in Table 2, it can be seen that the physical properties of the white board prepared were the best when the cellulase was used in an amount of 92IU/g and the ligninase was used in an amount of 33IU/g (i.e., the white board 10).

Example 3 Effect of different enzyme treatment times on physical Properties of white board

In order to investigate the influence of the modified OCC pulp on the physical properties of the white board paper by different enzyme treatment times and seek to find the most suitable enzyme treatment time, the following experimental design is adopted in this example:

in the preparation of OCC slurry, mixed enzyme solution with cellulase dosage of 92IU/g and ligninase dosage of 33IU/g is adopted for treatment, different enzyme treatment time is set, meanwhile, the step of adding cationic polymer into OCC slurry is avoided, so as to analyze and determine the most appropriate enzyme treatment time, the specific enzyme treatment time is shown in Table 3,

TABLE 3 treatment time of cellulase and ligninase in OCC pulp

1. Preparation of various slurries:

(3) Preparing OCC slurry:

b. The OCC pulp is treated by using cellulase and ligninase, the concentration of the OCC pulp is adjusted to 4-8 wt%, the cellulase and ligninase are added for treatment, the treatment temperature is 50 ℃, the pH value is 8, the dosage of the cellulase is 92IU/g, the dosage of the ligninase is 33IU/g, and the treatment time is shown in Table 3.

2. Preparation of slurries at different levels

3. Manufacturing base paper:

4. Coating, soft calendering and coiling:

5. White board paper test result

The physical properties of the white board 13-18 prepared by the method are detected, and the physical property indexes are quantification, transverse stiffness, folding endurance (transverse) bursting index, interlayer strength and ring crush index, wherein,

quantitatively detecting the coated white board according to GB/T451.2;

measurement of folding resistance of coated white cardboard paper GB/T1539-

The physical properties of the white board prepared from OCC pulp with different enzyme treatment time are shown in Table 4

TABLE 4 physical Properties of white paperboard 13-18

From the results in table 4, it can be seen that the physical properties of the white board paper are improved with the increase of the enzyme treatment time, but when the enzyme treatment time exceeds 95min, the increase of the enzyme treatment time will decrease the physical properties of the white board paper, and the reason for this phenomenon may be the same as the reason for increasing the enzyme concentration, that is, the cellulase and the ligninase remove the fine fibers in the OCC pulp, so that the content of the medium-long fibers is increased, which is beneficial for improving the physical properties of the white board paper, but the medium-long fibers will be affected accordingly and decrease the physical properties of the white board paper with the increase of the enzyme treatment time. From the results in Table 4, it can be seen that the optimum enzyme treatment time was 90min (i.e., the white board 16) when the cellulase amount was 92IU/g and the ligninase amount was 33 IU/g.

EXAMPLE 4 Effect of different amounts of cationic Polymer P (St-BA-AA-GMA) added to modify OCC pulps on the physical Properties of white paperboard

To investigate the effect of different cationic polymer P (St-BA-AA-GMA) addition levels on the physical properties of white board paper with an effort to find the most suitable cationic polymer P (St-BA-AA-GMA) addition level, the following experimental design was used in this example:

in the preparation of OCC slurry, treatment was not carried out with cellulase and ligninase, and different enzyme treatment times were set, and cationic polymer P (St-BA-AA-GMA) was added to OCC slurry to analyze and determine the addition amount of the cationic polymer P (St-BA-AA-GMA), and the addition amount of the specific cationic polymer P (St-BA-AA-GMA) was as shown in Table 5,

TABLE 5 amount of cationic polymer P (St-BA-AA-GMA) added to OCC slurries

1. Preparation of various slurries:

(3) Preparing OCC slurry:

b. Adding a cationic polymer to modify OCC slurry, wherein the cationic polymer is P (St-BA-AA-GMA), styrene (St), Butyl Acrylate (BA), Acrylic Acid (AA) and Glycidyl Methacrylate (GMA) are taken as monomers, hexadecyl trimethyl ammonium chloride (CTAC) is taken as an emulsifier, azodiisobutyl imidazole hydrochloride (AIBA) is taken as an initiator, and synthesizing the cationic polymer P (St-BA-AA-GMA) by adopting a semi-continuous emulsion polymerization method, and the specific method comprises the following steps:

introducing nitrogen, adding deionized water, a dissolved emulsifier and a sodium acetate buffer, starting a stirring device to stir so as to enable the emulsifier to be uniformly dissolved in water, then adding St, BA and AA mixed monomers, pre-emulsifying for a certain time, heating to (80 +/-1) DEG C, dropwise adding the rest GMA, BA and St mixed monomers (the dropwise adding speed is controlled to be 5 s/drop), dropwise adding a dissolved AIBA initiator, keeping the pH value between 6 and 8 by adding the sodium acetate buffer, reacting for 3.5h at 80 ℃ after the dropwise adding is finished, naturally cooling to 40-50 ℃ and discharging, wherein the dosage of St, BA, AA and GMA is 7:11:0.2:1.8, preparing an emulsion with 2 g/L by using a cationic polymer P (St-BA-AA-GMA), adding the emulsion into OCC slurry, specifically referring to table 5, stirring for 40min at the room temperature of 25 ℃ and reserving for later use.

2. Preparation of slurries at different levels

3. Manufacturing base paper:

4. Coating, soft calendering and coiling:

conveying the coating base paper subjected to hard calendering to a curtain coater, performing curtain coating on a front sizing layer of the coating base paper to form a curtain coating, and then carrying out curtain coating on the curtain coatingThe coating base paper forming the curtain coating layer is sent to a blade coating machine for blade coating to form a top coating layer, wherein the coating weight of the curtain coating layer is 11g/m²The coating weight of the top coating is 15g/m². After coating, soft press polishing, reeling, rewinding and warehousing.

5. White board paper test result

The physical properties of the white board 19-24 prepared by the method are detected, and the physical property indexes are quantification, transverse stiffness, folding endurance (transverse) bursting index, interlayer strength and ring crush index, wherein,

quantitatively detecting the coated white board according to GB/T451.2;

measurement of folding resistance of coated white cardboard paper GB/T1539-

the stiffness of the coated white board was determined according to GB/T22364-.

The effect of the addition of different cationic polymers P (St-BA-AA-GMA) on the physical properties of the white board is shown in Table 6.

TABLE 6 physical Properties of white paperboard 19-24

It can also be seen from the results of table 6 that as the addition amount of the cationic polymer P (St-BA-AA-GMA) increases, the physical properties of the white board also improve, but when the addition amount of the cationic polymer P (St-BA-AA-GMA) reaches a certain amount, the tendency of the physical properties of the white board to increase is slowed down, and the reason for this phenomenon may be that the cationic polymer P (St-BA-AA-GMA) improves the physical properties of the paper by binding the high density positive charges thereof to the negative charges of the cellulose in the pulp, and when the addition amount of P (St-BA-AA-GMA) reaches a certain amount, the main factor for the improvement of the physical properties is no longer the deficiency in the positive charge density but is a problem of the quality of the fiber. From the results in Table 6, it can be seen that the cationic polymer P (St-BA-AA-GMA) was added in an amount of 1.5% (corresponding to the absolute dry pulp) (i.e., the white board 23) and the physical properties of the white board were the best.

Example 5 Effect of simultaneous enzymatic modification of OCC pulp and addition of cationic Polymer on the physical Properties of white Board paper

It can be seen from the above examples that the physical properties of the white board can be improved to some extent by modifying the OCC slurry with enzyme or adding cationic polymer to the OCC slurry, and this example further explores whether the physical properties of the white board can be improved by simultaneously modifying the OCC slurry with enzyme and adding cationic polymer, and the experimental design is as follows:

the OCC pulp is modified by selecting the optimal enzyme treatment concentration and time determined in the above embodiment, namely when the dosage of the cellulase is 92IU/g and the dosage of the ligninase is 33IU/g, the optimal enzyme treatment time is 90min and the addition amount of the optimal cationic polymer P (St-BA-AA-GMA) is 1.5 percent (equivalent to absolute dry pulp), and the specific steps are as follows:

1. preparation of various slurries:

(3) Preparing OCC slurry:

introducing nitrogen, adding deionized water, a dissolved emulsifier and a sodium acetate buffer, starting a stirring device, and stirring to uniformly dissolve the emulsifier in the water; and adding St, BA and AA mixed monomers, pre-emulsifying for a certain time, heating to 80 +/-1 ℃, dropwise adding the rest GMA, BA and St mixed monomers (the dropwise adding speed is controlled to be 5 s/drop), dropwise adding a dissolved AIBA initiator, and adding a sodium acetate buffer to keep the pH value between 6 and 8. After the dropwise addition, reacting at 80 ℃ for 3.5h, naturally cooling to 40-50 ℃, and discharging, wherein the dosage of St, BA, AA and GMA is 7:11:0.2: 1.8;

preparing an emulsion with cationic polymer P (St-BA-AA-GMA) of 2 g/L, adding the emulsion into the OCC slurry treated by the cellulase and the ligninase in the step b, wherein the specific dosage is 1.5 percent (relative to absolute dry slurry), and stirring at room temperature of 25 ℃ for 40min for later use.

2. Preparation of slurries at different levels

3. Manufacturing base paper:

4. Coating, soft calendering and coiling:

the coating base paper after hard calendering is sent to a curtain coater, and curtain coating is carried out on the front sizing layer of the coating base paperForming a curtain coating layer on the cloth, and then sending the coating base paper forming the curtain coating layer to a blade coating machine for blade coating to form a top coating layer, wherein the coating weight of the curtain coating layer is 11g/m²The coating weight of the top coating is 15g/m². After coating, soft press polishing, reeling, rewinding and warehousing.

5. White board paper test result

The physical properties of the white board paper 25 prepared by the method are detected, and the physical property indexes are quantification, transverse stiffness, folding endurance (transverse) burst index, interlaminar strength and ring crush index, wherein,

quantitatively detecting the coated white board according to GB/T451.2;

measurement of folding resistance of coated white cardboard paper GB/T1539-

the stiffness of the coated white board was determined according to GB/T22364-.

The white board paper 25 prepared by the above method has the following physical properties as shown in table 7:

TABLE 7 physical Properties of white board 25

As shown in Table 7, the OCC pulp modified by enzyme and the OCC pulp modified by adding the cationic polymer are both greatly improved in physical properties compared with a single modification mode, which shows that cellulose and ligninase remove fine fibers in the OCC pulp, so that the proportion of medium and long fibers is improved, the fiber quality of the pulp is improved, and the physical properties of the paper are further improved in a synergistic manner by combining the high-density positive charges of the cationic polymer P (St-BA-AA-GMA) with the negative charges of cellulose in the paper pulp, so that a good effect is obtained.

The invention has been described in detail with respect to a general description and specific embodiments thereof, but it will be apparent to those skilled in the art that modifications and improvements can be made based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.

Claims

1. The coated white board comprises a surface layer, a lining layer, a core layer and a bottom layer, and is characterized in that the lining layer is made of OCC pulp, the OCC pulp is treated by cellulase and ligninase, cationic polymer P (St-BA-AA-GMA) is added, the dosage of the cellulase is 92IU/g, and the dosage of the ligninase is 33 IU/g; the treatment time of the cellulase and the ligninase is 90min, the adding amount of the P (St-BA-AA-GMA) is 1.5 percent, and the preparation method of the cationic polymer P (St-BA-AA-GMA) comprises the following steps: introducing nitrogen, adding deionized water, a dissolved emulsifier and a sodium acetate buffer, starting a stirring device, and stirring to uniformly dissolve the emulsifier in the water; then adding a mixed monomer of styrene (St), Butyl Acrylate (BA) and Acrylic Acid (AA), pre-emulsifying for a certain time, heating to 80 +/-1 ℃, dropwise adding the rest of Glycidyl Methacrylate (GMA), Butyl Acrylate (BA) and the mixed monomer of styrene (St), controlling the dropwise adding speed at 5 s/drop, dropwise adding dissolved azobisisobutylimidazole hydrochloride (AIBA) initiator, and adding a sodium acetate buffer to keep the pH value between 6 and 8;

and (3) reacting for 3.5h at 80 ℃ after the dropwise addition, naturally cooling to 40-50 ℃, and discharging, wherein the dosage of a mixed monomer of styrene (St), Butyl Acrylate (BA) and Acrylic Acid (AA) and Glycidyl Methacrylate (GMA) is 7:11:0.2: 1.8.

2. The coated white board according to claim 1, wherein the top layer comprises ONP and DIP pulps as top layer pulps, wherein the ONP and DIP pulps are used in a ratio of 2: 1; the lining layer comprises lining layer slurry of ONP slurry and OCC slurry, wherein the using ratio of the ONP slurry to the OCC slurry is 1: 1; the bottom layer comprises ONP slurry and OCC slurry which are bottom layer slurry, wherein the using ratio of the ONP slurry to the OCC slurry is 1: 3.

3. The method of making a coated white board according to any of claims 1-2, characterized in that the method is as follows:

(1) preparing ONP slurry, DIP slurry and OCC slurry;

(2) preparing sizing agents of the surface layer, the lining layer, the core layer and the bottom layer;

(3) manufacturing raw paper;

(4) coating, soft calendering and coiling; the liner is made of OCC pulp, the OCC pulp is treated by cellulase and ligninase, a cationic polymer P (St-BA-AA-GMA) is added, the dosage of the cellulase is 92IU/g, the dosage of the ligninase is 33IU/g, the treatment time of the cellulase and ligninase is 90min, and the addition amount of the P (St-BA-AA-GMA) is 1.5%.

4. The method of claim 3, wherein the OCC slurry is prepared by the steps of:

b. treating the OCC pulp by using cellulase and ligninase, adjusting the concentration of the OCC pulp to 4-8 wt%, adding the cellulase and ligninase for treatment, wherein the treatment temperature is 50 ℃, the pH value is 8, the treatment time is 90min, the dosage of the cellulase is 92IU/g, and the dosage of the ligninase is 33 IU/g;