CN111188224A

CN111188224A - Myopia-preventing paper and preparation method thereof

Info

Publication number: CN111188224A
Application number: CN202010005972.5A
Authority: CN
Inventors: 刘泽华; 应广东; 吴文春; 危志斌; 张伟; 周天; 李广东; 张翠云
Original assignee: Shandong Taiyang Honghe Paper Industry Co ltd; Yanzhou Tianzhang Paper Industry Co ltd; SHANDONG TAIYANGZHIYE CO Ltd
Current assignee: Shandong Taiyang Honghe Paper Industry Co ltd; Yanzhou Tianzhang Paper Industry Co ltd; SHANDONG TAIYANGZHIYE CO Ltd
Priority date: 2020-01-03
Filing date: 2020-01-03
Publication date: 2020-05-22
Anticipated expiration: 2040-01-03
Also published as: CN111188224B

Abstract

The invention provides anti-myopia paper and a preparation method thereof, and the preparation raw materials of the anti-myopia paper comprise pulp and papermaking chemicals, wherein the pulp comprises the following components in parts by mass: 20-60 parts of softwood pulp, 1-40 parts of hardwood pulp and 10-70 parts of chemi-mechanical pulp; the papermaking chemicals added to each 100 parts of the pulp comprise, by mass: 0.1-2.0 parts of wet-end cationic starch, 0.1-1.0 part of retention aid, 0.01-5 parts of internal sizing agent, 0.001-0.05 part of dye and 10-50 parts of filler. According to the myopia-preventing paper and the preparation method thereof, the color of the paper accords with the optimal optical range of myopia prevention, and the myopia-preventing paper has good paper strength, whiteness and smoothness, excessive additives are not required to be additionally added in the preparation method, and the damaged paper pulp generated in the paper making process and the fibers in white water are fully utilized, so that the discharge of paper making waste is reduced, and the cost of raw materials is reduced.

Description

Myopia-preventing paper and preparation method thereof

Technical Field

The invention belongs to the technical field of papermaking, and particularly relates to anti-myopia paper and a preparation method thereof.

Background

At present, the number of myopia patients in China is as much as 6 hundred million, which is almost half of the total population number in China. The myopia rates of high school students and college students exceed seven-generation and increase year by year, and the myopia rate of teenagers is high in the world first, which seriously threatens the national security of China. At present, students in China still commonly adopt 'white paper' with higher whiteness, the white paper can truly and objectively reflect all colors of printed pictures and texts, the contrast and the definition of the characters are improved, books look bright in color, but the books are too white, the contrast of the colors can be increased, the reflected light is too strong, visual nerves can be excessively stimulated, visual fatigue is caused, and myopia is very easily induced. On the other hand, in order to pursue the whiteness of paper, manufacturers often add some fluorescent whitening agents, and these additives not only have adverse effects on the health of teenagers, but also increase the cost of enterprises and pollute the environment. Therefore, in order to meet the increasing performance indexes of health, environmental protection, comfort and the like of people and the user experience requirements, the beige paper without any fluorescent whitening agent for preventing myopia is required.

Chinese patent document CN104611983B proposes a method for producing myopia-preventing paper with 50.8% brightness and 510nm reflection wavelength by using straw or waste paper as raw material, through crushing, screening, fiber size mixing and coloring, dewatering and forming, but the paper produced by using renewable resources has poor performance in strength, smoothness, whiteness, sizing degree, etc., and is difficult to meet the requirements of high-grade office cultural paper such as high-grade writing paper, copy paper, printing paper, etc.; in order to improve strength indexes such as crack resistance of paper, chinese patent document CN105040514 has developed a myopia prevention paper added with basic bright yellow, benzidine yellow, titanium dioxide, realgar, polyacrylonitrile fiber and acrylamide copolymer, which, although making up for the deficiencies of strength, smoothness and sizing degree to some extent, increases production cost and difficulty of later-stage paper recycling and wastewater treatment due to excessive additives. Therefore, a myopia prevention paper with high environmental protection property, which has good paper strength, whiteness and smoothness and does not use excessive additives, is needed.

Disclosure of Invention

The technical problem to be solved by the invention is to provide the myopia-preventing paper and the preparation method thereof, the color of the paper accords with the optimal optical range of myopia prevention, and the myopia-preventing paper has good paper strength, whiteness and smoothness, and excessive additives do not need to be additionally added in the preparation method.

In order to solve the problems, the invention provides anti-myopia paper, and the preparation raw materials of the anti-myopia paper comprise pulp and papermaking chemicals, wherein,

the slurry comprises the following components in parts by weight: 20-60 parts of softwood pulp, 1-40 parts of hardwood pulp and 10-70 parts of chemi-mechanical pulp; the papermaking chemicals added to each 100 parts of the pulp comprise, by mass: 0.1-2.0 parts of wet-end cationic starch, 0.1-1.0 part of retention aid, 0.01-5 parts of internal sizing agent, 0.001-0.05 part of dye and 10-50 parts of filler.

It should be noted that, the mass of the slurry referred to herein is the absolute dry mass of the slurry. Softwood pulp refers to softwood chemical pulp; hardwood pulp refers to hardwood chemical pulp; chemi-mechanical pulp refers to chemi-mechanical pulp, and specifically refers to pulp obtained by a pulping method employing chemical pretreatment and mechanical defibering post-treatment.

Preferably, the slurry comprises the following components in parts by weight: 32-43 parts of softwood pulp, 12-28 parts of hardwood pulp and 30-50 parts of chemi-mechanical pulp; the papermaking chemicals added to each 100 parts of the pulp comprise, by mass: 0.6-1.2 parts of wet-end cationic starch, 0.255-0.64 part of retention aid, 0.05-2.5 parts of internal sizing agent, 0.009-0.025 part of dye and 20-35 parts of filler.

Preferably, the chemi-mechanical pulp is APMP pulp, the APMP pulp refers to alkaline hydrogen peroxide bleaching chemi-mechanical pulp, the APMP pulp is used as pulp, the yield is high, the production cost can be reduced, on the other hand, the whiteness of the APMP pulp is generally about 70% (ISO), the whiteness can be accepted for producing the beige writing paper, the use of a whitening agent is avoided, the production cost is reduced, and particularly, the APMP pulp can be poplar APMP pulp.

Under the preferable formula of the sizing agent and the papermaking chemicals, the obtained anti-myopia paper has the color within the optimal optical range and has the optimal paper strength, whiteness and smoothness.

Preferably, the stock also comprises 10-30 parts of broke pulp. The invention makes full use of the broke produced in the paper making process of the paper machine, recycles the waste and changes waste into valuable.

Wherein, the wet-end cationic starch refers to starch added in the wet end, and is added before paper making, and has the functions of strengthening, drainage assisting, retention assisting and the like with fibers.

The retention aid is a chemical for improving retention of fibers and fillers in a paper machine wire part, specifically, a conventional retention aid which mainly comprises high polymers and is added with alum, polyaluminium chloride and the like can be selected, and a microparticle retention aid can also be selected, and the retention aid is composed of high polymers and microparticles such as cationic polyacrylamide, organic microparticles and the like, wherein the microparticles can be bentonite, colloidal silica and the like; preferably, the retention aid comprises: 0.02-0.07 part of polyacrylamide, 0.2-0.45 part of bentonite and 0.035-0.12 part of organic micro-polymer.

The internal sizing agent can be rosin, starch, modified starch PVA, or neutral internal sizing agent, such as alkenyl succinic anhydride ASA, alkyl ketene dimer AKD; preferably, the internal sizing agent is 0.5 to 2.5 parts of alkyl ketene dimer or 0.05 to 0.15 parts of alkenyl succinic anhydride.

Preferably, the dye is a liquid yellow dye. Compared with the solid dye commonly adopted in the prior art, the liquid dye adopted by the invention avoids the problem of color spots caused by incomplete dissolution and uneven dyeing of the solid dye, so that the prepared paper has no color spots, the paper is uniformly colored and the like, and the optical performance is greatly improved. Specifically, the liquid yellow dye may be a liquid yellow dye of type 3 GN-Z.

Preferably, the filler may be ground calcium carbonate, light calcium carbonate or other filler types commonly used in the art for papermaking.

The invention also aims to provide a method for preparing the anti-myopia paper, which comprises the following steps:

s1, pulping, namely preparing softwood pulp, hardwood pulp and chemi-mechanical pulp;

s2, preparing pulp, namely mixing the softwood pulp, the hardwood pulp and the chemi-mechanical pulp, and then sequentially performing first screening, adding the wet-end cationic starch, flushing and diluting, adding the dye and the filler, degritting, degassing, adding the in-pulp sizing agent, performing second screening and adding the retention aid to obtain screened and purified pulp;

and S3, papermaking, namely, sequentially passing the screened and purified pulp through a pulp flowing box to perform net-surfing dehydration, squeezing dehydration, drying in a front drying part, gluing by a glue applicator, drying in a rear drying part, press polishing by a soft calender and reeling to obtain the myopia-preventing paper.

According to the invention, by reasonably setting the adding positions and working sections of the wet-end cationic starch, the internal sizing agent, the dye, the retention aid and the filler, the added chemicals and the pulp are uniformly mixed and fully reacted, so that the effects of improving the retention rate of the pulp, enhancing the strength of the paper and improving the water resistance of the paper are achieved, and the purposes of clean and efficient production are also ensured.

Preferably, the method also comprises the steps of disintegrating the broke generated in the process of the wire part, the press part, the front drying part, the rear drying part and the reeling, concentrating to obtain broke pulp, and mixing the broke pulp with softwood pulp, hardwood pulp and chemi-mechanical pulp for pulp preparation.

Preferably, the method also comprises the steps of filtering white water generated in the wire part and the press part by a multi-disc filter to obtain recycled fibers, and mixing the recycled fibers with the softwood pulp, the hardwood pulp and the chemi-mechanical pulp to prepare pulp.

Preferably, the method specifically comprises the following steps:

s1, pulping, comprising the following steps:

s101, softwood pulp is pulped by a pulper, residue is removed by a sand remover, and then the softwood pulp is obtained by pulping by a high-taper refiner, wherein the pulping concentration of the softwood pulp is not less than 4.8%, and the beating degree after grinding is 30-42 DEG SR, wherein the high-taper refiner is provided with a special refiner disc for the softwood pulp, fiber cutting and devillicating fibrillation are taken as main functions in the pulping process of the softwood pulp, and compared with pulping equipment such as a double-disc grinder and a cylindrical die, the pulping equipment has the advantages of higher fiber strength of a pulping product, better refining effect of the softwood pulp and lower energy consumption;

s102, the hardwood pulp is pulped by a pulper, then slag is removed by a desander, and then the hardwood pulp is obtained by pulping by a large-taper refiner, wherein the pulping concentration of the hardwood pulp is not less than 4.8%, and the beating degree after grinding is 22-30 DEG SR, wherein the large-taper refiner is provided with a special refiner plate for the hardwood pulp, fibers of the hardwood pulp are mainly subjected to devillicate broom in the pulping process of the refiner, and are repeatedly subjected to the actions of friction force, kneading force, distortion and shearing force, and compared with other types of pulping equipment, the pulping effect is good, and the pulping energy consumption is low;

s103, removing slag of the chemi-mechanical pulp by a sand remover to obtain the chemi-mechanical pulp, wherein the beating degree of the chemi-mechanical pulp is 40-48 degrees SR;

s104, breaking broke generated in the process of a net section, a pressing section, a front drying section, a rear drying section and coiling, and then concentrating to obtain the broke pulp;

s105, filtering white water generated by the net part and the pressing part in the papermaking process by using a multi-disc filter, and collecting recycled fibers by using a fiber recycling tank to obtain the recycled fibers;

s2, preparing the pulp, which comprises the following steps:

s201, softwood pulp, hardwood pulp, chemi-mechanical pulp, broke pulp and recycled fibers are mixed, screened by three sections of medium-consistency sieves for removing residues and sent to a papermaking forehearth, the pulp inlet concentration of the three sections of medium-consistency sieves is 2.5% -3.6%, the pulp inlet pressure is 50-500kPa, the pressure difference between the pulp inlet and the good pulp is 0-50kPa, and the deslagging period of the third section of medium-consistency sieves is 10-120 min;

s202, adding wet cationic starch into slurry screened by a three-section medium-concentration screen, then flushing and diluting the slurry by an external white water tank, adding dye and filler, desanding the slurry by a five-section desander, and degassing the slurry by a degasser after desanding, wherein the slurry inlet pressure of the second, third and fourth sections of desanders is 200-450kPa, and the good slurry pressure is 30-300 kPa;

s203, adding the slurry after degassing into an internal sizing agent, then feeding the slurry into a paper machine sieve for screening through a fan pump, adding polyacrylamide before the paper machine sieve, and adding organic micro-polymer and bentonite after the paper machine sieve to obtain screened and purified slurry, wherein the pulp inlet pressure of the paper machine sieve is 200-700kPa, and the pressure difference between the pulp inlet and the good pulp is 0-60 kPa;

s3, papermaking, comprising the following steps:

s301, feeding the screened and purified pulp into a pulp flowing box, then, carrying out online dewatering, wherein the concentration of the online pulp is 0.8-1.8%, the speed difference of a pulp screen is-50 m/min, the proportion of dilution water is 8-20%, the vacuum degree of a screen part forming roller is 0-15kPa, the vacuum degree of a wet forming box is 0-15kPa, the vacuum degree of a wet suction box is 0-35kPa, the vacuum degree of a vacuum couch roller is 0-63kPa, and the vacuum degree of a high vacuum water suction box is 0-65 kPa;

s302, conveying the wet paper sheet dehydrated and formed by the net part to a pressing part for pressing and dehydrating, wherein the pressing pressure of a first pressing shoe is 700-plus-material 1100kN/m, the pressing pressure of a second pressing shoe is 700-plus-material 1100kN/m, and the dryness of the paper sheet out of the pressing part is 45-55 percent;

s303, delivering the squeezed wet paper to a front drying part for front drying, delivering the wet paper to a sizing machine for sizing after the drying is finished, delivering the wet paper to a rear drying part for sizing and then drying, wherein the pressure of an inter-roller nip of the sizing machine is 5-20kN/m, and the pressure between a metering rod and a sizing roller is 100-200 kPa;

s304, conveying the paper dried by the post-drying part to a soft calender for soft calendering, wherein the surface temperature of a soft calendering hot roller is not higher than 180 ℃, the linear pressure of a nip is 10-150kN/m, and then coiling the paper to obtain the anti-myopia paper.

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

1. the anti-myopia paper is beige in color, and has the optical properties as follows: d65(ISO) brightness: 73-77%; cie (iso) whiteness: 34-38%, L: 91-95 parts of paper, 1.6-2.0 parts of a and 11.1-11.7 parts of b, the paper is in the optimal optical range of the myopia-preventing textbook paper, has uniform color, no color spots and no chromatic aberration, and can prevent myopia of teenagers when used as the textbook paper;

2. the myopia-preventing paper has good physical properties by blending the components of the formula, selecting the types of sizing agents and retention aids in the formula, regulating and controlling process parameters, normally adding the myopia-preventing paper and not adding reinforcing agents, wherein the bulk, strength, whiteness, smoothness, tear strength and folding strength of the myopia-preventing paper are all in a better value range, and the strength property of the myopia-preventing paper can completely meet the requirements of high-grade office cultural paper such as high-grade writing paper, copy paper, printing paper and the like;

3. according to the myopia-preventing paper and the preparation method thereof, softwood pulp, hardwood pulp and chemi-mechanical pulp are used as pulp, the chemi-mechanical pulp yield is high, the production cost can be reduced, the whiteness is about 70% generally, the whiteness can be accepted for producing the beige writing paper, the use of a whitening agent is avoided, the cost is saved, and the pollution to the environment is reduced;

4. the preparation method of the myopia-preventing paper further recycles broke produced in the process of preparing, namely the net part, the press part, the front drying part, the rear drying part and the reeling part, simultaneously recycles fibers of white water produced in the net part and the press part through the multi-disc filter in the papermaking process, mixes the recycled broke pulp and recycled fibers with softwood pulp, hardwood pulp and chemi-mechanical pulp to be used as pulp, fully utilizes waste produced in papermaking, changes waste into valuable, reduces production cost and protects ecological environment.

Drawings

FIG. 1 is a process flow chart of the method for preparing the anti-myopia paper.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it should be understood 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 one

The myopia prevention paper comprises the following raw materials in parts by mass: 32 parts of softwood pulp, 12 parts of hardwood pulp, 30 parts of poplar APMP pulp and 10 parts of broke pulp; according to the mass portion, the papermaking chemicals added into every 100 portions of pulp comprise: 0.6 part of wet cationic starch, 0.02 part of polyacrylamide, 0.2 part of bentonite, 0.035 part of organic micropolymer, 0.05 part of alkenyl succinic anhydride, 0.009 part of liquid yellow dye 3GN-Z and 20 parts of calcium carbonate.

As shown in fig. 1, the preparation method of the myopia-preventing paper according to the embodiment includes the following steps:

s1, pulping, comprising the following steps:

s101, pulping softwood pulp by a pulper, removing slag by a high-concentration desander, and pulping by a high-taper refiner to obtain the softwood pulp, wherein the pulping concentration of the softwood pulp is 5.2%, and the beating degree after grinding is 35 oSR;

s102, pulping hardwood pulp by a pulper, removing slag by a high-concentration desander, and pulping by a large-taper refiner to obtain the hardwood pulp, wherein the pulping concentration of the hardwood pulp is 5.2%, and the beating degree after grinding is 25-degree SR;

s103, removing slag of the poplar APMP slurry through a high-concentration desander to obtain poplar APMP slurry, wherein the beating degree of the poplar APMP slurry is 45-degree SR;

s104, breaking broke generated in the process of the net section, the pressing section, the front drying section, the rear drying section and the coiling section, and then concentrating to obtain broke pulp;

and S105, filtering the white water generated in the net part and the pressing part by a multi-disc filter in the papermaking process, and collecting and recycling the fibers by a fiber recycling tank to obtain recycled fibers.

S2, preparing the pulp, which comprises the following steps:

s201, softwood pulp, hardwood pulp, poplar APMP pulp, damaged pulp and recycled fibers are mixed, screened and deslagging is carried out through three sections of medium-consistency screens, the mixture is sent to a papermaking forebay, the pulp inlet concentration of the three sections of medium-consistency screens is 3.5%, the pulp inlet pressure is 100kPa, the pressure difference between the pulp inlet and the good pulp is 20kPa, and the deslagging period of the third section of medium-consistency screens is 60 min;

s202, adding the wet-end cationic starch into the slurry screened by the three-section medium-consistency screen, then flushing and diluting the slurry by an external white water tank, adding a liquid yellow dye 3GN-Z and a filler calcium carbonate, desanding the slurry by a five-section desander, and degassing the slurry by a degasser after desanding, wherein the slurry inlet pressure of the second, third and fourth sections of desanders is 300kPa, and the good slurry pressure is 100 kPa;

s203, adding alkenyl succinic anhydride into the degassed slurry, then feeding the slurry into a paper machine sieve for screening through a fan pump, adding polyacrylamide before the paper machine sieve, and adding organic micro-polymer and bentonite after the paper machine sieve to obtain screened and purified slurry, wherein the pulp inlet pressure of the paper machine sieve is 300kPa, and the pressure difference between the pulp inlet and the good pulp is 30 kPa;

s3, papermaking, comprising the following steps:

s301, feeding the screened and purified pulp into a pulp flowing box, then, carrying out online dewatering, wherein the concentration of the online pulp is 1%, the speed difference of a pulp net is 30m/min, the proportion of dilution water is 10%, the vacuum degree of a net forming roller is 10kPa, the vacuum degree of a wet forming box is 10kPa, the vacuum degree of a wet suction box is 20kPa, the vacuum degree of a vacuum couch roller is 50kPa, and the vacuum degree of a high vacuum suction box is 50 kPa;

s302, conveying the wet paper sheet dehydrated and formed by the net part to a pressing part for pressing and dehydrating, wherein the line pressing pressure of a first pressing shoe is 800kN/m, the line pressing pressure of a second pressing shoe is 1000kN/m, and the dryness of the paper sheet discharged from the pressing part is 50%;

s303, delivering the squeezed wet paper to a front drying part for front drying, delivering the wet paper to a sizing machine for sizing after the drying is finished, delivering the wet paper to a rear drying part for sizing and then drying, wherein the pressure of an inter-roller pressing area of the sizing machine is 10kN/m, and the pressure between a metering rod and a sizing roller is 150 kPa;

s304, the paper dried by the rear drying part is sent to a soft calender for soft calendering, the surface temperature of a soft calendering hot roller is 180 ℃, the linear pressure of a press area is 80kN/m, and then the paper is rolled to obtain the anti-myopia paper.

Example two

The myopia prevention paper comprises the following raw materials in parts by mass: 43 parts of softwood pulp, 28 parts of hardwood pulp, 50 parts of poplar APMP pulp and 30 parts of broke pulp; according to the mass portion, the papermaking chemicals added into every 100 portions of pulp comprise: 1.2 parts of wet-end cationic starch, 0.07 part of polyacrylamide, 0.45 part of bentonite, 0.12 part of organic micro-polymer, 2.5 parts of alkyl ketene dimer, 0.025 part of liquid yellow dye 3GN-Z and 35 parts of calcium carbonate.

The preparation method of the myopia-preventing paper is the same as that in the first embodiment.

EXAMPLE III

The myopia prevention paper comprises the following raw materials in parts by mass: 35 parts of softwood pulp, 20 parts of hardwood pulp, 40 parts of poplar APMP pulp and 20 parts of broke pulp; according to the mass portion, the papermaking chemicals added into every 100 portions of pulp comprise: 1 part of wet-end cationic starch, 0.05 part of polyacrylamide, 0.3 part of bentonite, 0.07 part of organic micro-polymer, 0.1 part of alkenyl succinic anhydride, 0.01 part of liquid yellow dye 3GN-Z and 30 parts of calcium carbonate.

Example four

The myopia prevention paper comprises the following raw materials in parts by mass: 40 parts of softwood pulp, 25 parts of hardwood pulp, 45 parts of poplar APMP pulp and 25 parts of broke pulp; according to the mass portion, the papermaking chemicals added into every 100 portions of pulp comprise: 0.8 part of wet-end cationic starch, 0.04 part of polyacrylamide, 0.4 part of bentonite, 0.1 part of organic micro-polymer, 2 parts of alkyl ketene dimer, 0.02 part of liquid yellow dye 3GN-Z and 32 parts of calcium carbonate.

EXAMPLE five

The myopia prevention paper comprises the following raw materials in parts by mass: 32 parts of softwood pulp, 28 parts of hardwood pulp, 50 parts of poplar APMP pulp and 25 parts of broke pulp; according to the mass portion, the papermaking chemicals added into every 100 portions of pulp comprise: 1.2 parts of wet cationic starch, 0.02 part of polyacrylamide, 0.45 part of bentonite, 0.035 part of organic micro-polymer, 0.09 part of alkenyl succinic anhydride, 0.025 part of liquid yellow dye 3GN-Z and 28 parts of calcium carbonate.

EXAMPLE six

The myopia prevention paper comprises the following raw materials in parts by mass: 20 parts of softwood pulp, 40 parts of hardwood pulp, 70 parts of poplar APMP pulp and 10 parts of broke pulp; according to the mass portion, the papermaking chemicals added into every 100 portions of pulp comprise: 2.0 parts of wet-end cationic starch, 0.25 part of polyacrylamide, 0.5 part of bentonite, 0.25 part of organic micro-polymer, 5 parts of alkyl ketene dimer, 0.05 part of liquid yellow dye 3GN-Z and 50 parts of calcium carbonate.

EXAMPLE seven

The myopia prevention paper comprises the following raw materials in parts by mass: 60 parts of softwood pulp, 1 part of hardwood pulp, 10 parts of poplar APMP pulp and 30 parts of broke pulp; according to the mass portion, the papermaking chemicals added into every 100 portions of pulp comprise: 0.1 part of wet-end cationic starch, 0.01 part of polyacrylamide, 0.07 part of bentonite, 0.02 part of organic micro-polymer, 0.01 part of alkenyl succinic anhydride, 0.001 part of liquid yellow dye 3GN-Z and 10 parts of calcium carbonate.

Example eight

The myopia prevention paper described in the embodiment has the same content of each component in the raw materials as that in the embodiment one, and is different only in that the sizing agent in the pulp is rosin. The preparation method of the myopia-preventing paper is the same as that in the first embodiment.

Example nine

The myopia-preventing paper in the embodiment is prepared by the same components as the myopia-preventing paper in the first embodiment, except that the retention aid comprises 0.02 part of high polymer and 0.235 part of alum. The preparation method of the myopia-preventing paper is the same as that in the first embodiment.

Example ten

The anti-myopia paper described in the embodiment has the same content of each component in the raw materials as that in the embodiment one, and is different only in that the dye is alkaline bright yellow.

EXAMPLE eleven

The raw material composition of the myopia-preventing paper is the same as that in the first embodiment, and the specific steps of the preparation method are the same as those in the first embodiment, except that:

in the step S101, the disintegration concentration of the softwood pulp is 4.8%, and the beating degree after grinding is 30 DEG SR;

in the step S102, the hardwood pulp disintegration concentration is 4.8%, and the beating degree after grinding is 22 DEG SR;

in step S103, the beating degree of the poplar APMP pulp is 40-degree SR;

in step S201, the pulp inlet concentration of the third section of medium consistency screen is 2.5%, the pulp inlet pressure is 50kPa, the pressure difference between the pulp inlet and the good pulp is 50kPa, and the slag discharge period of the third section of medium consistency screen is 30 min;

in step S202, the pulp inlet pressure of the second, third and fourth sand removers is 200kPa, and the good pulp pressure is 30 kPa;

in step S203, the pulp inlet pressure of a paper machine screen is 200kPa, and the pressure difference between the inlet pulp and the good pulp is 60 kPa;

in step S301, the concentration of the upper-wire sizing agent is 0.8%, the speed difference of the sizing net is 50m/min, the proportion of the dilution water is 8%, the vacuum degree of the forming roller of the net part is 15kPa, the vacuum degree of the wet forming box is 15kPa, the vacuum degree of the wet suction box is 10kPa, the vacuum degree of the vacuum couch roller is 30kPa, and the vacuum degree of the high vacuum suction box is 65 kPa;

in step S302, the line pressing pressure of a first pressing shoe is 700kN/m, the line pressing pressure of a second pressing shoe is 700kN/m, and the pressing dryness of paper sheets is 45%;

in step S303, the pressure of a nip between rollers of the sizing machine is 5kN/m, and the pressure between the metering rod and the sizing roller is 100 kPa;

in step S304, the soft calendering hot roll surface temperature is 150 ℃ and the nip line pressure is 10 kN/m.

Example twelve

in the step S101, the disintegration concentration of the softwood pulp is 4.8%, and the beating degree after grinding is 42 DEG SR;

in the step S102, the hardwood pulp disintegration concentration is 4.8%, and the beating degree after grinding is 30 DEG SR;

in step S103, the beating degree of the poplar APMP pulp is 48 degrees SR;

in step S201, the pulp inlet concentration of the three sections of medium-consistency sieves is 3.6%, the pulp inlet pressure is 500kPa, the pressure difference between the pulp inlet and the good pulp is 25kPa, and the slag discharge period of the third section of medium-consistency sieves is 120 min;

in step S202, the pulp inlet pressure of the second, third and fourth sand removers is 450kPa, and the good pulp pressure is 300 kPa;

in step S203, the pulp inlet pressure of a paper machine screen is 700kPa, and the pressure difference between the inlet pulp and the good pulp is 30 kPa;

in step S301, the concentration of the upper wire sizing agent is 1.8%, the speed difference of the sizing net is 50m/min, the proportion of the dilution water is 20%, the vacuum degree of the net part forming roll is 15kPa, the vacuum degree of the wet forming box is 15kPa, the vacuum degree of the wet suction box is 35kPa, the vacuum degree of the vacuum couch roll is 63kPa, and the vacuum degree of the high vacuum suction box is 65 kPa;

in step S302, the line pressing pressure of a first pressing shoe is 1100kN/m, the line pressing pressure of a second pressing shoe is 1100kN/m, and the paper sheet squeezing dryness is 55%;

in step S303, the pressure of the nip between the rollers of the sizing machine is 20kN/m, and the pressure between the metering rod and the sizing roller is 200 kPa;

in step S304, the soft calendering hot roll surface temperature is 150 ℃ and the nip line pressure is 150 kN/m.

EXAMPLE thirteen

in the step S101, the disintegration concentration of the softwood pulp is 3.2%, and the beating degree after grinding is 20 DEG SR;

in the step S102, the hardwood pulp disintegration concentration is 3.2%, and the beating degree after grinding is 15 DEG SR;

in step S103, the beating degree of the poplar APMP pulp is 30-degree SR;

in step S201, the pulp inlet concentration of the three sections of medium-consistency sieves is 2%, the pulp inlet pressure is 20kPa, the pressure difference between the pulp inlet and the good pulp is 25kPa, and the slag discharge period of the third section of medium-consistency sieves is 120 min;

in step S202, the pulp inlet pressure of the second, third and fourth sand removers is 100kPa, and the good pulp pressure is 300 kPa;

in step S203, the pulp inlet pressure of a paper machine screen is 100kPa, and the pressure difference between the inlet pulp and the good pulp is 30 kPa;

in step S301, the concentration of the upper-wire sizing agent is 0.4%, the speed difference of the sizing net is 50m/min, the proportion of the dilution water is 5%, the vacuum degree of the forming roller of the net part is 15kPa, the vacuum degree of the wet forming box is 15kPa, the vacuum degree of the wet suction box is 35kPa, the vacuum degree of the vacuum couch roller is 63kPa, and the vacuum degree of the high vacuum suction box is 65 kPa;

in step S302, the line pressing pressure of a first pressing shoe is 500kN/m, the line pressing pressure of a second pressing shoe is 500kN/m, and the pressing dryness of paper sheets is 40%;

in step S303, the pressure of the nip between the rollers of the sizing machine is 20kN/m, and the pressure between the metering rod and the sizing roller is 50 kPa;

in step S304, the soft calendering hot roll surface temperature is 180 ℃ and the nip line pressure is 60 kN/m.

Example fourteen

in the step S101, the disintegration concentration of the softwood pulp is 3.2%, and the beating degree after grinding is 50 DEG SR;

in the step S102, the hardwood pulp disintegration concentration is 3.2%, and the beating degree after grinding is 40 DEG SR;

in step S103, the beating degree of the poplar APMP pulp is 60-degree SR;

in step S201, the pulp inlet concentration of the three sections of medium-consistency sieves is 5%, the pulp inlet pressure is 600kPa, the pressure difference between the pulp inlet and the good pulp is 60kPa, and the slag discharge period of the third section of medium-consistency sieves is 120 min;

in step S202, the pulp inlet pressure of the second, third and fourth sand removers is 500kPa, and the good pulp pressure is 400 kPa;

in step S203, the pulp inlet pressure of a paper machine screen is 800kPa, and the pressure difference between the inlet pulp and the good pulp is 70 kPa;

in step S301, the concentration of the sizing agent on the wire is 2%, the speed difference of the sizing net is 50m/min, the proportion of the dilution water is 25%, the vacuum degree of the forming roller of the net part is 15kPa, the vacuum degree of the wet forming box is 15kPa, the vacuum degree of the wet suction box is 35kPa, the vacuum degree of the vacuum couch roller is 63kPa, and the vacuum degree of the high vacuum suction box is 65 kPa;

in step S303, the pressure of a nip between rollers of the sizing machine is 25kN/m, and the pressure between the metering rod and the sizing roller is 250 kPa;

Paper performance testing

The optical performance and the physical performance of the anti-myopia paper obtained in each embodiment are tested, and the performance test results of the anti-myopia paper obtained in each embodiment are shown in the following table.

TABLE 1

According to the test results, the paper color of the anti-myopia paper accords with the optical range of anti-myopia. Research shows that for the anti-myopia paper, the optimal optical parameter range is as follows: d65 brightness: 73-77%; CIE whiteness: 34-38%, L: 91-95, a:1.6-2.0, b:11.1-11.7, therefore, the color brightness and whiteness of the paper of six, seven, eight, nine, ten, thirteen, fourteen are slightly low, while the above-mentioned embodiments one, two, three, four, five, eleven, twelve are the preferred embodiments, in the preferred formula and process parameter range, the optical performance of the paper can reach the optimal optical range suitable for preventing myopia, the color chroma of the paper is optimal, the color is uniform, and no color spot exists.

TABLE 2

According to the test results, the anti-myopia paper has the advantages that the paper color is beyond the optimal optical range of anti-myopia, the physical performance is good, and the paper strength is good.

The formulas of the sizing agents and the papermaking chemicals in the first, second, third, fourth and fifth examples are in the preferred range of the invention, and compared with the formulas of the sixth, seventh, eighth, ninth and tenth examples in the non-preferred range, the paper strength of the myopia-preventing paper obtained by the raw material formula in the preferred range is optimal, wherein the solid dye is selected from the dyes in the tenth example, and compared with the liquid dye in the application, the paper in the tenth example has a little color spot and poor dyeing uniformity. The raw material formulas of the eleventh, twelfth, thirteenth and fourteenth examples are the same as those of the first example, the specific process parameters adopted by the preparation method are different, compared with the thirteenth and fourteenth examples, the eleventh and twelfth colors in the preferred ranges are in the optimal optical range for preventing myopia, and the paper strength is optimal.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.

Claims

1. The myopia-preventing paper is characterized in that raw materials for preparing the myopia-preventing paper comprise pulp and papermaking chemicals, wherein,

the slurry comprises the following components in parts by weight: 20-60 parts of softwood pulp, 1-40 parts of hardwood pulp and 10-70 parts of chemi-mechanical pulp;

the papermaking chemicals added to each 100 parts of the pulp comprise, by mass: 0.1-2.0 parts of wet-end cationic starch, 0.1-1.0 part of retention aid, 0.01-5 parts of internal sizing agent, 0.001-0.05 part of dye and 10-50 parts of filler.

2. The anti-myopia paper according to claim 1,

the slurry comprises the following components in parts by weight: 32-43 parts of softwood pulp, 12-28 parts of hardwood pulp and 30-50 parts of chemi-mechanical pulp;

the papermaking chemicals added to each 100 parts of the pulp comprise, by mass: 0.6-1.2 parts of wet-end cationic starch, 0.255-0.64 part of retention aid, 0.05-2.5 parts of internal sizing agent, 0.009-0.025 part of dye and 20-35 parts of filler.

3. The anti-myopia paper according to claim 2, wherein the pulp further comprises 10-30 parts of broken pulp.

4. The anti-myopia paper of claim 1, wherein the retention aid comprises: 0.02-0.07 part of polyacrylamide, 0.2-0.45 part of bentonite and 0.035-0.12 part of organic micro-polymer.

5. Anti-myopia paper according to claim 1, characterized in that the internal size agent is 0.5-2.5 parts of alkyl ketene dimer or 0.05-0.15 parts of alkenyl succinic anhydride.

6. The anti-myopia paper according to claim 1, wherein the dye is a liquid yellow dye.

7. A method for preparing the myopia-preventing paper as claimed in any one of claims 1 to 6, which comprises the following steps:

s1, pulping, namely preparing the softwood pulp, the hardwood pulp and the chemi-mechanical pulp;

and S3, papermaking, namely sequentially carrying out online dewatering, squeezing dewatering, drying in a front drying part, gluing by a glue applicator, drying in a rear drying part, press polishing by a soft calender and reeling on the screened and purified pulp by a pulp flowing box to obtain the myopia-preventing paper.

8. The method for preparing myopia prevention paper according to claim 7, further comprising disintegrating broke generated during the wire section, the press section, the front drying section, the rear drying section, and the winding process, and then concentrating to obtain broke pulp, and mixing with the softwood pulp, the hardwood pulp, and the chemi-mechanical pulp to prepare the pulp.

9. The method for preparing myopia prevention paper according to claim 8, further comprising filtering white water generated in the wire part and the press part through a multi-disc filter to obtain recycled fibers, and mixing the recycled fibers with the softwood pulp, the hardwood pulp and the chemi-mechanical pulp to prepare pulp.

10. The method for preparing myopia-preventing paper according to claim 9, which is characterized by comprising the following steps:

s1, pulping, comprising the following steps:

s101, pulping softwood pulp by a pulper, removing slag by a sand remover, and pulping by a high-taper refiner to obtain the softwood pulp, wherein the pulping concentration of the softwood pulp is not less than 4.8%, and the beating degree after grinding is 30-42 DEG SR;

s102, pulping hardwood pulp by a pulper, removing slag by a sand remover, and pulping by a high-taper refiner to obtain the hardwood pulp, wherein the pulping concentration of the hardwood pulp is not less than 4.8%, and the beating degree after grinding is 22-30 DEG SR;

s2, preparing the pulp, which comprises the following steps:

s201, mixing the softwood pulp, the hardwood pulp, the chemi-mechanical pulp, the damaged pulp and the recycled fibers, screening and deslagging through three sections of medium-consistency sieves, and sending the mixture into a pulp making front pool, wherein the pulp inlet concentration of the three sections of medium-consistency sieves is 2.5% -3.6%, the pulp inlet pressure is 50-500kPa, the pressure difference between the pulp inlet and the good pulp is 0-50kPa, and the deslagging period of the third section of medium-consistency sieves is 10-120 min;

s202, adding the wet-end cationic starch into slurry screened by a three-section medium-concentration screen, then flushing and diluting the slurry by an external white water tank, adding the dye and the filler, desanding the slurry by a five-section desander, and degassing the slurry by a degasser after desanding, wherein the slurry inlet pressure of the second, third and fourth sections of desanders is 200-450kPa, and the good slurry pressure is 30-300 kPa;

s203, adding the slurry after degassing into the internal sizing agent, then feeding the slurry into a paper machine sieve for screening through a fan pump, adding polyacrylamide before the paper machine sieve, and adding organic micro polymer and bentonite after the paper machine sieve to obtain screened and purified slurry, wherein the pulp inlet pressure of the paper machine sieve is 200-700kPa, and the pressure difference between the pulp inlet and the good pulp is 0-60 kPa;

s3, papermaking, comprising the following steps:

s301, feeding the screened and purified slurry into a flow box, and then, carrying out online dewatering, wherein the concentration of the online slurry is 0.8-1.8%, the speed difference of a slurry net is-50 m/min, the proportion of dilution water is 8-20%, the vacuum degree of a net part forming roller is 0-15kPa, the vacuum degree of a wet forming box is 0-15kPa, the vacuum degree of a wet suction box is 0-35kPa, the vacuum degree of a vacuum couch roller is 0-63kPa, and the vacuum degree of a high vacuum water suction box is 0-65 kPa;

s303, delivering the squeezed wet paper to a front drying part for drying, delivering the wet paper to a sizing machine for sizing after the drying is finished, delivering the wet paper to a rear drying part for sizing and then drying, wherein the pressure of an inter-roller nip of the sizing machine is 5-20kN/m, and the pressure between a metering rod and a sizing roller is 100-200 kPa;