Antireflection type eye protection functional paper and preparation method thereof

Abstract

The application provides a kind of anti-reflective eye protection functional paper and its preparation method; the preparation method uses coating of specific content component, cooperates specific process step, realizes overall better interaction, and the anti-reflective eye protection functional paper prepared is compared with coated base paper, the diffuse reflectance in harmful blue-violet light area (400-480nm) and ultraviolet light area (especially UVA, wavelength range is 315-400nm) is reduced by 10.07% at 315nm, 6.77% at 400nm, can effectively reduce the damage of harmful light to human eye retina, reaches the prevention myopia and eye protection effect; at the same time, the anti-reflective eye protection functional paper is compared with coated base paper, the reflectivity in 500-700nm wave band of human eye reading comfort increases 0.2%, further guarantees the reading experience of reader.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of papermaking process, more particularly, to a reflection-reducing eye-protecting functional paper and a preparation method thereof. BACKGROUND

[0002] In order to strengthen the prevention and control of myopia in children and adolescents, and promote the vision health of children and adolescents, the Office of the Ministry of Education and other 15 departments jointly issued the "Children and Adolescents Myopia Prevention and Control Bright Action Work Plan (2021-2025)", which specifically proposes that in order to improve the visual environment of children and adolescents, combined with the specific requirements of "Health Requirements for Myopia Prevention and Control of Children and Adolescents Learning Supplies", to ensure that children and adolescents use textbooks, teaching materials, learning magazines, schoolwork books, test papers, learning newspapers, and preschool children's learning materials, and encourage the purchase and use of certified anti-myopia eye protection products. It is worth noting that among the above eye protection paper products related to children and adolescents, textbooks and teaching materials have attracted the attention of parents and publishers due to their characteristics of repeated reading and long-term use.

[0003] Before developing anti-myopia eye protection products, it is necessary to sort out and summarize the scientific indicators of eye protection technology from the principle of eye injury. Overall, visible blue-violet light and invisible ultraviolet light have higher energy and greater damage to the eyes. First, visible short-wave blue-violet light can penetrate the lens of the human eyeball and act on the retina, causing the retina to produce free radicals, leading to the death of retinal pigment epithelial cells, causing light-sensitive cells to lack nutrients and causing vision damage, producing macular changes, squeezing and shrinking the lens, and causing myopia. At the same time, the degree of damage of blue-violet light to the eyes varies with age, and relevant studies have shown that blue-violet light has the greatest damage to the eyes of children and adolescents. Second, ultraviolet light directly acts on the cornea and lens of the eye, and the cornea and lens absorb most of the ultraviolet light, increasing the curvature of the cornea; at the same time, the lens of the eye ages faster, and the density of the liquid in the lens gradually increases, and after the density increases, the refractive index of the lens increases (the lens is essentially a convex lens), causing the focusing ability to increase, and the degree of myopia of the eye will also increase. Therefore, scientifically meaningful eye protection technology and paper products should mainly focus on the optical regulation technology route related to harmful blue-violet light and ultraviolet light.

[0004] Children and adolescents in the actual life learning, there are various light source environment, in addition to the help of different types of light to assist reading, in most cases in the conventional daylight (natural light) environment reading using teaching materials, and the content of ultraviolet light in the sunlight is about 6%. Therefore, the paper eye protection technology should work in various light source environment, not just hope to improve the light source environment, should start from the optical performance of the paper itself, effectively reduce the harmful short wave blue-violet light and ultraviolet light (mainly UVA, wavelength range 320~400nm) on the surface of paper products reflectivity, so that the harmful light reflected into the human eye retina is reduced, at the same time without affecting the overall reading experience, ultimately realize the scientific sense of myopia prevention and eye protection effect.

[0005] However, the current market myopia prevention and eye protection technology and paper products are mainly based on non-fluorescent and color adjusting technology, that is, without adding fluorescent whitening agent, by using dye (mainly yellow dye), simply adjust the optical performance of paper (only focus on D65 brightness) to the range required in the national standard "Hygienic requirements for myopia prevention and control of learning supplies for children and adolescents" (GB 40070-2021), while meeting the basic requirements of quantitative, fluorescent brightness, smoothness, etc., there is no specific prevention measures for harmful blue-violet light and even ultraviolet light which can cause substantial damage to the eyes, therefore, from the perspective of eye protection science and technology, none of them belong to the strict sense of eye protection functional paper products.

[0006] Therefore, it is urgent to develop a kind of anti-reflective eye protection functional paper product for harmful blue-violet light and ultraviolet light, to reduce the harmful reflection of the two light zones to the human eye during use, so as to effectively prevent myopia and play the effect of eye protection. SUMMARY

[0007] Therefore, the purpose of the present application is to provide a kind of anti-reflective eye protection functional paper and its preparation method, based on a new kind of anti-reflective functional coating, the eye protection paper product is obtained by in-machine coating treatment, compared with the coated base paper, the eye protection paper product in harmful blue-violet light zone (400~480nm) and ultraviolet light zone (especially UVA, wavelength range 315~400nm) diffuse reflectance is reduced by 10.07% at 315nm and 6.77% at 400nm, which can effectively reduce the damage of harmful light to the human eye retina, achieve the effect of preventing myopia and eye protection; at the same time, compared with the coated base paper, the reflectivity of the eye protection paper product in the 500~700nm wavelength range which is comfortable for human eye reading is increased by 0.2%, which further ensures the reading experience of the reader.

[0008] The present application provides a kind of anti-reflective eye protection functional paper and its preparation method, including the following steps:

[0009] a) mixing bleached softwood kraft pulp, hardwood kraft pulp and poplar mechanical pulp, adding wet-end chemical auxiliaries, preparing pulp mixture to obtain mixed pulp;

[0010] b) forming the mixed pulp obtained in step a) into wet paper, pre-drying, coating, post-drying and calender finishing to obtain the anti-reflective eye protection functional paper;

[0011] The coating formula used for coating comprises, by weight: 20-30 parts of nano cerium oxide, 20-30 parts of nano zinc oxide, 30-40 parts of inorganic nano blue light absorber, 15-30 parts of nano aluminum oxide, 1-5 parts of food-grade vegetable carbon black dispersion liquid, 1-4 parts of transparent plastic pigment dispersion liquid, 5-10 parts of water-based zinc stearate dispersion liquid, 10-40 parts of styrene-butadiene latex or acrylic latex, 5-15 parts of color fixing agent, 0.5-1 part of sodium carboxymethyl cellulose or polyvinyl alcohol, and 1-2 parts of dispersant.

[0012] Preferably, the beating degree of the bleached softwood kraft pulp in step a) is 300±25 mL, the beating degree of the hardwood kraft pulp is 325±25 mL, and the beating degree of the poplar mechanical pulp is 150±25 mL.

[0013] The mass ratio of the bleached softwood kraft pulp, the hardwood kraft pulp and the poplar mechanical pulp is (28-32):(28-32):40.

[0014] Preferably, the wet-end chemical auxiliaries in step a) comprise:

[0015] filler 300-350 kg / t paper, cationic starch 12-15 kg / t paper, retention aid 0.5-0.7 kg / t paper, bentonite 2.5-4.0 kg / t paper, sizing agent 15-18 kg / t paper, organic microparticles 0.35-0.55 kg / t paper, fixing agent 0.3-0.7 kg / t paper, and yellow dye 0.07-0.13 kg / t paper.

[0016] Preferably, the filler is composed of light calcium carbonate and heavy calcium carbonate in a mass ratio of (1-3):1; the retention aid is cationic polyacrylamide; and the sizing agent is quick-acting alkyl ketene dimer emulsion.

[0017] Preferably, the process of wet paper forming in step b) is specifically:

[0018] The mixed pulp is pumped into a first-stage four-section conical degritting device for purification and degritting, then into a degassing tank for degassing treatment, and then into a pressure screen for screening treatment, and then sent to a headbox for netting, to adjust the netting flow and control the basis weight of the paper sheet to be 70-90 g / m 2The wet paper web is discharged from the wire section and enters a press section for five-roller three-pressing-area compound pressing, and is pressed to a dryness of ≥35% before being subjected to front and rear drying.

[0019] Preferably, the temperature of the front drying in step b) is 105-130°C, and the paper web is dried to a dryness of ≥92%.

[0020] Preferably, the coating amount in step b) is 3-4g / m 2 ;

[0021] The coating pressure is controlled as follows:

[0022] The pressing area pressure is 16-24kN / m on the driving side and 16-24kN / m on the operating side.

[0023] The metering rod pressurizing pressure is 0.6-1.2bar on the upper roller and 0.6-1.2bar on the lower roller.

[0024] Preferably, the temperature of the rear drying in step b) is 105-130°C, and the paper web is dried to a dryness of ≥93.5%.

[0025] Preferably, the calendering temperature of the calender finishing in step b) is 50-60°C, the first-pressing pressurizing is 870-890KN / m, and the second-pressing pressurizing is 900-910KN / m.

[0026] The application further provides an anti-reflective eye-protecting functional paper prepared by the preparation method.

[0027] This invention provides an anti-reflective eye-protecting functional paper and its preparation method. The preparation method includes the following steps: a) mixing bleached softwood sulfate pulp, hardwood sulfate pulp, and poplar chemimechanical pulp, adding wet-end chemical additives, and preparing a mixed pulp; b) sequentially subjecting the mixed pulp obtained in step a) to wet paper forming, pre-drying, coating, post-drying, and calendering to obtain the anti-reflective eye-protecting functional paper; the coating formulation used for coating, by weight, includes: 20-30 parts of nano-cerium oxide, 20-30 parts of nano-zinc oxide, 30-40 parts of inorganic nano-blue light absorber, 15-30 parts of nano-alumina, 1-5 parts of food-grade plant carbon black dispersion, 1-4 parts of transparent plastic pigment dispersion, 5-10 parts of aqueous zinc stearate dispersion, 10-40 parts of styrene-butadiene latex or acrylic latex, 5-15 parts of fixing agent, 0.5-1 parts of sodium carboxymethyl cellulose or polyvinyl alcohol, and 1-2 parts of dispersant. Compared with existing technologies, the preparation method provided by this invention uses coatings with specific content components and specific process steps to achieve better overall interaction. Compared with coated base paper, the diffuse reflectance of the prepared anti-reflective eye-protecting functional paper is reduced by 10.07% at 315nm and by 6.77% at 400nm in the harmful blue-violet light region (400-480nm) and ultraviolet light region (especially UVA, wavelength range of 315-400nm), respectively. This can effectively reduce the damage of harmful light to the human retina and achieve the effects of preventing myopia and protecting the eyes. At the same time, compared with coated base paper, the reflectance of this anti-reflective eye-protecting functional paper is increased by 0.2% in the 500-700nm wavelength range where the human eye is comfortable to read, further ensuring the reader's reading experience. Attached Figure Description

[0028] Figure 1 This is a comparison chart of the complete diffuse reflectance curves of Example 1 of the present invention and the coated base paper (i.e., Comparative Example 1, ordinary offset paper) in the range of 200-700 nm.

[0029] Figure 2 This is a comparison chart of the complete diffuse reflectance curves of Example 2 of the present invention and the coated base paper (i.e., Comparative Example 1, ordinary offset paper) in the range of 200-700nm. Detailed Implementation

[0030] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] This invention provides a method for preparing anti-reflective eye-protecting functional paper, comprising the following steps:

[0032] a) mixing bleached softwood kraft pulp, hardwood kraft pulp and poplar APMP, adding wet-end chemical auxiliaries, performing pulp mixing to obtain mixed pulp;

[0033] b) sequentially performing wet paper forming, pre-drying, coating, post-drying and calender finishing on the mixed pulp obtained in step a) to obtain the anti-reflective eye-protecting functional paper;

[0034] The coating formula used for the coating comprises, by weight, 20-30 parts of nano cerium oxide, 20-30 parts of nano zinc oxide, 30-40 parts of inorganic nano blue light absorber, 15-30 parts of nano aluminum oxide, 1-5 parts of food-grade vegetable carbon black dispersion liquid, 1-4 parts of transparent plastic pigment dispersion liquid, 5-10 parts of water-based zinc stearate dispersion liquid, 10-40 parts of butylphenyl latex or acrylic latex, 5-15 parts of color fixing agent, 0.5-1 part of sodium carboxymethyl cellulose or polyvinyl alcohol, and 1-2 parts of dispersant.

[0035] The bleached softwood kraft pulp, the hardwood kraft pulp and the poplar APMP are mixed first, then wet-end chemical auxiliaries are added, and pulp mixing is performed to obtain mixed pulp.

[0036] The bleached softwood kraft pulp (NBKP), the bleached hardwood kraft pulp (LBKP) and the self-produced Italian poplar APMP (APMP) are particularly selected as the main raw materials for papermaking, and the paper product is further endowed with the optical performance related to the eye-protecting scientific elements through the coating of the specific formula on the basis of ensuring the printability, gloss, smoothness and other indicators of the paper.

[0037] In the present application, the beating degree (measured by Canadian freeness) of the bleached softwood kraft pulp is preferably 300±25 mL, the beating degree of the hardwood kraft pulp is preferably 325±25 mL, and the beating degree of the poplar APMP is preferably 150±25 mL; the raw materials after beating are mixed respectively.

[0038] In the present application, the mass ratio of the bleached softwood kraft pulp, the hardwood kraft pulp and the poplar APMP is preferably (28-32):(28-32):40.

[0039] In the present application, the wet-end chemical auxiliaries (the addition amount is measured by kg / t of paper) preferably comprise:

[0040] Filler 300-350 kg / t paper, cationic starch 12-15 kg / t paper, retention aid 0.5-0.7 kg / t paper, bentonite 2.5-4.0 kg / t paper, sizing agent 15-18 kg / t paper, organic microparticle 0.35-0.55 kg / t paper, fixing agent 0.3-0.7 kg / t paper, yellow dye 0.07-0.13 kg / t paper;

[0041] More preferably consists of:

[0042] Filler 300 kg / t paper, cationic starch 14-15 kg / t paper, retention aid 0.5-0.7 kg / t paper, bentonite 3-4.0 kg / t paper, sizing agent 15-17 kg / t paper, organic microparticle 0.35-0.45 kg / t paper, fixing agent 0.3-0.5 kg / t paper, yellow dye 0.07-0.09 kg / t paper.

[0043] The present application does not have special restrictions on the source of each raw material in the above-mentioned wet part chemicals and auxiliaries, and commercially available goods known to those skilled in the art can be used.

[0044] In the present application, the filler uses two kinds of calcium carbonate composite fillers, preferably composed of light calcium carbonate and heavy calcium carbonate with a mass ratio of (1-3):1, and the specific amount is controlled according to the ash content requirement; the retention aid is preferably cationic polyacrylamide; the sizing agent is preferably fast-acting alkyl ketene dimer emulsion (AKD), and the water absorption of the raw paper, i.e. the Cobb value, is controlled at 20-27 g / m 2 between by adjusting the amount of AKD during actual addition; in addition, a small amount of yellow dye is added to adjust the whiteness of the paper.

[0045] After obtaining the mixed pulp, the obtained mixed pulp is sequentially subjected to wet paper forming, pre-drying, coating, post-drying and polishing finishing to obtain an anti-reflective eye protection functional paper;

[0046] In the present application, the process of wet paper forming is preferably specifically:

[0047] The mixed pulp is pumped into a first four-section conical slag remover for purification and slag removal, then enters a degassing tank for degassing treatment, and then enters a pressure screen for screening treatment, and then is sent to a headbox, the flow rate is adjusted, and the basis weight of the paper sheet is controlled to be 70-90 g / m 2 ; the wet paper sheet after the headbox enters a press section for five-roll three-pressing-area composite pressing, and after pressing to a dryness ≥ 35%, pre-drying and post-drying are performed; the above steps can be implemented by using equipment known to those skilled in the art, and the purpose is to obtain a formed wet paper, and ordinary offset paper can be obtained by drying and other processes based on the prior art.

[0048] In the present application, the temperature of the pre-drying is preferably 105-130 DEG C, and the paper sheet dryness is preferably > 92 %.

[0049] In the present application, the coating (anti-reflective eye protection coating) formula used for coating comprises, by weight: nano cerium oxide 20-30 parts, nano zinc oxide 20-30 parts, inorganic nano blue light absorber 30-40 parts, nano alumina 15-30 parts, food-grade plant carbon black dispersion liquid 1-5 parts, transparent plastic pigment dispersion liquid 1-4 parts, aqueous zinc stearate dispersion liquid 5-10 parts, styrene-butadiene latex or acrylic latex 10-40 parts, color fixing agent 5-15 parts, sodium carboxymethyl cellulose or polyvinyl alcohol 0.5-1 part, dispersant 1-2 parts.

[0050] Preferably consists of the following components:

[0051] Nano cerium oxide 20-30 parts, nano zinc oxide 20-30 parts, inorganic nano blue light absorber 30-35 parts, nano alumina 15-20 parts, food-grade plant carbon black dispersion liquid 1-2 parts, transparent plastic pigment dispersion liquid 3-4 parts, aqueous zinc stearate dispersion liquid 5-5 parts, styrene-butadiene latex or acrylic latex 25-35 parts, color fixing agent 8-12 parts, sodium carboxymethyl cellulose or polyvinyl alcohol 0.7-0.9 parts, dispersant 1.4-1.6 parts.

[0052] The present application does not have special restrictions on the source of the above-mentioned raw material components, and commercially available goods known to those skilled in the art can be used.

[0053] In the present application, the coating used for coating is preferably coated by a water-based dispersion system; the water-based dispersion system is preferably a coating starch water dispersion liquid diluted with water to a mass fraction of 10 %; the present application adds each raw material component in the above-mentioned anti-reflective eye protection coating to the surface sizing starch, and carries out the coating process, while ensuring the uniformity of sizing and preventing uneven sizing; the starch is preferably cassava raw starch.

[0054] In the present application, the particle size of the nano cerium oxide (CeO2) is preferably 20-100 nm, more preferably 20-50 nm, and more preferably 50 nm.

[0055] In the present application, the particle size of the nano zinc oxide (ZnO) is preferably 20-50 nm, more preferably 30 nm, and the surface morphology presents a nano-rod structure.

[0056] In the present application, the inorganic nano blue light absorber can precisely absorb ultraviolet rays and harmful blue light in the 320-460 nm wave band, effectively protecting the eyes from blue light damage, while having no significant absorption effect on visible light in the 440-780 nm wave band; the inorganic nano blue light absorber preferably selects appropriate inorganic nano materials such as zinc oxide, silicon dioxide, aluminum oxide, zirconium oxide, titanium oxide as a substrate and is synthesized by chemical or physical methods (preferably sol-gel method or precipitation method in chemical method), in order to improve the stability and dispersibility of the nanoparticles, preferably a layer of organic or inorganic material can also be coated, or a specific functional group is introduced for modification (surface modification), and the final material appears light yellow, which has little effect on the transparency and color of the product.

[0057] In the present application, the particle size of the nano-aluminum oxide (Al2O3) is preferably 20-200 nm, more preferably 20-100 nm, and more preferably 30-50 nm.

[0058] In the present application, the food-grade plant carbon black dispersion liquid uses water as a dispersant, and has a large number of active groups such as carboxyl and hydroxyl groups on its surface, and has excellent light absorption and anti-reflection performance; the solid content of the food-grade plant carbon black dispersion liquid is preferably 0.1-0.3%, and more preferably 0.2%.

[0059] In the present application, the transparent plastic pigment dispersion liquid is preferably a dispersion liquid of polymethyl methacrylate powder (PMMA) in a 20-40% aqueous polyurethane system, and the particle size is preferably 10-50 nm, wherein the PMMA content is preferably 5-15%.

[0060] In the present application, the solid content of the aqueous zinc stearate dispersion liquid is preferably 30-40%, and the particle size is preferably 400-600 nm; zinc stearate has a certain ultraviolet absorption capacity, although the absorption effect is weak, but can protect the eye protection function paper with a higher proportion of mechanical pulp from ultraviolet damage to a certain extent, and delay the aging of the paper.

[0061] In the present application, the solid content of the butylbenzene latex or acrylic latex is preferably 30-50%.

[0062] In the present application, the fixing agent is preferably pyridine-3-carboxylic acid, which is a white crystalline powder, mainly exists in animal viscera and muscle tissue, and is one of the 13 essential vitamins for the human body, and is healthy and non-toxic.

[0063] In the present application, the coating amount of the coating is preferably 3-4 g / m 2 ;

[0064] The coating pressure control is preferably:

[0065] The nip pressure is preferably 16-24 kN / m on the drive side and 16-24 kN / m on the operating side.

[0066] The metering rod pressure is preferably 0.6-1.2 bar on the upper roll and 0.6-1.2 bar on the lower roll.

[0067] In the present application, the temperature of the post-drying is preferably 105-130 DEG C, and the paper is dried to a dryness of preferably >93.5%.

[0068] The present application does not have special restrictions on the implementation device of the pre-drying and post-drying, and a drying cylinder known to those skilled in the art can be used.

[0069] In the present application, the paper obtained by the post-drying is subjected to calendering treatment, and then is wound after finishing, so that the anti-reflective eye-protecting functional paper with good surface flatness and printing performance is obtained.

[0070] In the present application, the calendering temperature of the calendering finishing is preferably 50-60 DEG C, the first pressure is preferably 870-890 KN / m, and the second pressure is preferably 900-910 KN / m.

[0071] The present application also provides an anti-reflective eye-protecting functional paper prepared by the preparation method.

[0072] The present application provides an anti-reflective environmental protection eye-protecting functional paper for harmful light based on a new functional coating material, which is prepared by the preparation method.

[0073] (1) Compared with conventional offset paper, the anti-reflective eye-protecting functional paper prepared by the present application has lower whiteness, is not dazzling, has soft vision, and has excellent printing effect; (2) Compared with conventional commercial eye-protecting paper products, the anti-reflective eye-protecting functional paper prepared by the present application has reduced reflected light, especially harmful blue-violet light (400-480 nm) and ultraviolet light (mainly 315-400 nm) which can cause damage to the human eye, and the harmful light in the ultraviolet-visible light region is reduced by 20-40% by the first systematic and comprehensive design of a directional functional coating, so that the harmful light received by the human eye retina is reduced, and the product has scientific anti-myopia and eye-protecting effects; the main use group of the product is children and adolescents or high-end customers with special requirements for the eye-protecting effect of the product, and the product has high added value and broad market prospects in the field of teaching materials for children and adolescents with high use frequency and long reading time.

[0074] The application provides an anti-reflective eye-protecting functional paper and a preparation method thereof; the preparation method comprises the following steps: a) mixing bleached softwood kraft pulp, hardwood kraft pulp and poplar chemical pulp, adding wet-end chemical auxiliaries, and preparing pulp to obtain mixed pulp; b) sequentially performing wet paper forming, pre-drying, coating, post-drying and calendering finishing on the mixed pulp obtained in step a) to obtain the anti-reflective eye-protecting functional paper; the coating formula used for coating comprises, by weight, 20-30 parts of nano cerium oxide, 20-30 parts of nano zinc oxide, 30-40 parts of inorganic nano blue light absorber, 15-30 parts of nano aluminum oxide, 1-5 parts of food-grade plant carbon black dispersion liquid, 1-4 parts of transparent plastic pigment dispersion liquid, 5-10 parts of water-based zinc stearate dispersion liquid, 10-40 parts of styrene-butadiene latex or acrylic latex, 5-15 parts of fixing agent, 0.5-1 part of sodium carboxymethyl cellulose or polyvinyl alcohol, and 1-2 parts of dispersant. Compared with the prior art, the preparation method provided by the application uses a coating with specific content components and a specific process step to realize overall good interaction, and the anti-reflective eye-protecting functional paper prepared by the method has a decrease of 10.07% in the diffuse reflectance at 315 nm and a decrease of 6.77% in the diffuse reflectance at 400 nm in the harmful blue-violet light region (400-480 nm) and the ultraviolet light region (especially UVA, wavelength range: 315-400 nm) compared with the coated base paper, which can effectively reduce the damage of harmful light to the human eye retina and achieve the effects of preventing myopia and eye protection; meanwhile, the anti-reflective eye-protecting functional paper has an increase of 0.2% in the reflectance in the 500-700 nm wavelength band which is comfortable for the human eye to read compared with the coated base paper, thereby further ensuring the reading experience of the reader.

[0075] In order to further illustrate the application, the following examples are used for detailed description. The raw materials used in the following examples of the application are commercially available; wherein the particle size of nano cerium oxide (CeO2) is 50 nm, the particle size of rod-shaped nano zinc oxide (ZnO) is 30 nm, the inorganic nano blue light absorber A1 is silicon dioxide (SiO2) provided by Zhenhuan New Material (Suzhou) Co., Ltd. (model: YT-SiO2-Y22, particle size: 50 nm), the inorganic nano blue light absorber A2 is zirconium oxide (ZrO2) provided by Changzhou Daxi Concentrated Nanometer Technology Co., Ltd. (model: DXN-ZR30, particle size: 30-50 nm), the particle size of nano aluminum oxide (Al2O3) is 30-50 nm, the solid content of the food-grade plant carbon black dispersion liquid is 0.2%, the transparent plastic pigment dispersion liquid is a dispersion liquid of polymethyl methacrylate powder (PMMA) in a 30% water-based polyurethane system, the particle size is 30 nm, and the PMMA content is 10%, the solid content of the water-based zinc stearate dispersion liquid is 35%, the particle size is 500 nm, the solid content of the styrene-butadiene latex and the acrylic latex is 40% respectively, and the fixing agent is pyridine-3-carboxylic acid.

[0076] Example 1

[0077] Firstly, three kinds of pulp, bleached softwood kraft pulp (NBKP, beating degree 300ml), hardwood kraft pulp (LBKP, beating degree 325ml) and poplar chemi-mechanical pulp (APMP, beating degree 150ml) were mixed in the ratio of 30wt%:30wt%:40wt% respectively. Then, 300kg / t paper of calcium carbonate filler was added in the ratio of light calcium:heavy calcium = 2:1 (mass ratio), and other wet-end chemicals were added, the specific addition of wet-end chemicals was as follows: the amount of cationic starch was 15kg / t paper, the amount of cationic polyacrylamide as retention aid was 0.6kg / t paper, the amount of bentonite was 4.0kg / t paper, the amount of sizing agent AKD (fast-acting alkyl alkenyl ketone dimer emulsion) was 16kg / t paper, the amount of organic particles was 0.4kg / t paper, the amount of fixing agent was 0.4kg / t paper, the amount of yellow dye was 0.08kg / t paper; the mixed pulp was pumped into a four-stage conical cleaner for purification and deslagging, and then into a deaeration tank for deaeration treatment, and then into a pressure screen for screening treatment, and then into a headbox for web forming, the web flow was adjusted to control the basis weight of the paper sheet to be 80g / m 2 ; after the wet paper sheet left the headbox, it entered the press section for five-roll three-press-zone compound pressing, and then entered the front drying section after being pressed to a dryness ≥39%; the paper sheet was dried in the drying cylinder with the surface temperature controlled at 105-130℃, until the dryness of the paper sheet was ≥92%; the paper sheet entered the in-machine coating machine for in-machine coating treatment: 10wt% coating starch diluted with water was used as the aqueous dispersion system, and 20 parts by weight of nano cerium oxide (CeO2), 30 parts by weight of rod-shaped nano zinc oxide (ZnO), 35 parts by weight of inorganic nano blue light absorber A1, 15 parts by weight of nano aluminum oxide (Al2O3), 1 part by weight of food-grade plant carbon black dispersion liquid, 4 parts by weight of transparent plastic pigment B dispersion liquid, 5 parts by weight of aqueous zinc stearate dispersion liquid, 30 parts by weight of butylphenyl latex, 10 parts by weight of color fixing agent, 0.8 parts by weight of sodium carboxymethyl cellulose (CMC), and 1.5 parts by weight of dispersant were added; the coating amount was 3-4g / m 2 ; the coating pressure was controlled as follows: press zone pressure: 20kN / m on the driving side and 20kN / m on the operating side; metering rod pressurization pressure: 1bar on the upper roll and 1bar on the lower roll; then the wet paper sheet treated by coating was subjected to post-drying in the surface sizing machine, the drying cylinder temperature was controlled at 105-130℃, and the dryness of the paper sheet after the post-drying section was ≥93.5%; the paper sheet entering from the post-drying section entered the calendering section for calendering treatment, the calendering temperature was controlled at 50-60℃, the first press pressure was 880KN / m, and the second press pressure was 900KN / m; after the calendering, the paper sheet was wound up, and a reduced-reflection eye protection functional paper with good surface smoothness and printing performance was obtained.

[0078] Figure 1The reflectivity values at different typical wavelengths are shown in Table 2, and the reflectivity curves of the eye-protecting functional paper of Example 1 and the ordinary offset paper of Comparative Example 1 in the full wave band of 200-700 nm ultraviolet-visible light are shown in Figure 1. Figure 1 Compared with the ordinary offset paper without coating treatment, the eye-protecting functional paper of Example 1 has a significantly reduced reflectivity of harmful light rays in the ultraviolet light region (mainly UVA, wavelength range of 315-400 nm) and the harmful blue-violet light region (mainly 400-480 nm), while the reflectivity of light rays in the wavelength range of 500-700 nm, which is comfortable for human eyes to read, is basically unchanged. Therefore, the anti-reflective eye-protecting paper provided by the present application can protect the eyes and prevent myopia while ensuring the comfort of reading.

[0079] Example 2

[0080] To better illustrate the effect of the anti-reflective coating material on the eye-protecting functional paper, in Example 2, all the processes before in-machine coating are kept consistent, so they are not repeated here. The difference lies in that the formula of the anti-reflective coating material used to produce the eye-protecting functional paper is different. In the in-machine coating stage, 10 wt% of the coating starch is used as the water-based dispersion system, 30 parts by weight of nano cerium oxide (CeO2), 20 parts by weight of rod-shaped nano zinc oxide (ZnO), 30 parts by weight of inorganic nano blue light absorber A2, 20 parts by weight of nano aluminum oxide (Al2O3), 1 part by weight of food-grade plant carbon black dispersion liquid, 4 parts by weight of transparent plastic pigment B dispersion liquid, 5 parts by weight of water-based zinc stearate, 30 parts by weight of acrylic latex, 10 parts by weight of color fixing agent, 0.8 parts by weight of polyvinyl alcohol (PVA), and 1.5 parts by weight of dispersant are added. The coating amount is 3-4 g / m 2 ; the coating pressure is controlled as follows: the nip pressure is 20 kN / m on the driving side and 20 kN / m on the operating side; the metering rod pressure is 1 bar on the upper roll and 1 bar on the lower roll; then the coated paper is sent to the surface sizing machine, and the wet paper sheet is further dried, with the drying cylinder temperature controlled at 105-130 ℃, and the paper sheet dryness after drying is ≥93.5%; the paper sheet entering from the drying section is sent to the calendering area for calendering treatment, with the calendering temperature controlled at 50-60 ℃, the first pressure being 880 KN / m, and the second pressure being 900 KN / m; after calendering, the paper sheet is wound up, and the anti-reflective eye-protecting functional paper with good surface smoothness and printing performance is obtained.

[0081] Figure 2 The reflectivity values at different typical wavelengths are shown in Table 2, and the reflectivity curves of the eye-protecting functional paper of Example 2 and the ordinary offset paper of Comparative Example 1 in the full wave band of 200-700 nm ultraviolet-visible light are shown in Figure 1. Figure 2The results show that, compared with the ordinary offset paper without coating treatment, the eye protection functional paper in the embodiment 2 of the present application has a significantly reduced reflectivity of the harmful light rays in the ultraviolet light region (mainly UVA, wavelength range of 315-400 nm) and the harmful blue-violet light region (mainly 400-480 nm), while the reflectivity of the light rays in the wavelength range of 500-700 nm which is comfortable for human eyes to read is basically unchanged; therefore, the anti-reflective eye protection paper provided by the present application can protect eyes and prevent myopia while ensuring the reading comfort.

[0082] Comparative example 1

[0083] First, three kinds of pulp, i.e. bleached softwood kraft pulp (NBKP, beating degree of 300ml), hardwood kraft pulp (LBKP, beating degree of 325ml) and poplar chemi-mechanical pulp (APMP, beating degree of 150ml) are mixed in a ratio of 30wt%:30wt%:40wt%. Then, 300kg / t paper of calcium carbonate filler is added in a ratio of light calcium:heavy calcium=2:1 (mass ratio), and other wet-end chemicals are added, specifically: 15kg / t paper of cationic starch, 0.6kg / t paper of cationic polyacrylamide as retention aid, 4.0kg / t paper of bentonite, 16kg / t paper of AKD (fast-acting alkyl alkenyl ketone dimer emulsion) as sizing agent, 0.4kg / t paper of organic particles, 0.4kg / t paper of fixing agent, and 0.08kg / t paper of yellow dye. The mixed pulp is pumped into a first-stage four-section conical cleaner for purification and deslagging, then into a deaeration tank for deaeration, and then into a pressure screen for screening, and then into a headbox for web forming, with the web forming flow being adjusted to control the basis weight of the paper sheet to be 80g / m 2 ; after the wet paper sheet leaves the headbox, it enters a five-roll three-pressing-zone compound press for pressing, and then enters a front drying section; the surface temperature of the drying cylinder is controlled to be 105-130℃ for drying the paper sheet, until the dryness of the paper sheet is ≥92%; then the paper sheet is dried in a back drying section with the drying cylinder temperature being controlled to be 105-130℃, and the dryness of the paper sheet after leaving the back drying section is ≥93.5%; the paper sheet entering from the back drying section enters a calendering section for calendering, with the calendering temperature being controlled to be 50-60℃, and the first pressure being 880KN / m and the second pressure being 900KN / m; after calendering, the paper sheet is wound up, and thus the ordinary offset paper with the same structure and manufacturing process as the eye protection functional paper in the embodiment 1 is obtained.

[0084] Performance test:

[0085] The conventional indexes of the eye protection functional paper, such as basis weight, D65 brightness, D65 fluorescent brightness, opacity, smoothness, etc. are tested, and the results are shown in Table 1.

[0086] Table 1: Conventional performance data

[0087]

[0088]

[0089] More importantly, in terms of optical reflection performance for specific wavelength light, the eye protection functional paper and its base paper samples were measured for diffuse reflectance in the wavelength range of 200-700 nm (test wavelength interval, i.e., 1 nm) using a Shimadzu UV-visible spectrophotometer (UV-2600i) in an integrating sphere mode. The results are shown in Table 2 below.

[0090] Table 2 Reflectance data

[0091] Indicator / different paper types Example 1 Example 2 Comparative Example 1 (coated base paper) Diffuse reflectance at 315 nm (%) 13.082 13.556 23.149 Diffuse reflectance at 400 nm (%) 61.901 62.187 68.666 Diffuse reflectance at 420 nm (%) 71.213 70.945 75.452 Diffuse reflectance at 600 nm (%) 82.239 80.818 82.201

[0092] As can be seen from Table 2, the reflection values of the anti-reflective eye protection functional paper produced in Examples 1-2 of the present application for harmful blue-violet light (wavelength generally 400-480 nm) and ultraviolet light (mainly UVA, i.e., low-frequency long-wave ultraviolet light with a wavelength of 315-400 nm) are greatly reduced compared to the conventional offset paper (Comparative Example 1, coated base paper). Specifically, at a typical wavelength of 315 nm in the ultraviolet light region, the reflection value is reduced by about 10% compared to the coated base paper in Comparative Example 1; at 400 nm, the reflection value is reduced by about 6-7%; at a typical wavelength of 420 nm in the harmful blue-violet light region, the reflection value is reduced by 4-5% compared to the coated base paper in Comparative Example 1; however, the eye protection paper of the present application has a visible light wavelength range of 500-700 nm that is more comfortable for the human eye to read (for example, the reflection value at 600 nm, and the complete full-wavelength reflectance curve are shown in Figure 2). Figures 1-2 wherein, Figure 1 is a comparison chart of the complete diffuse reflectance curves of Example 1 of the present application and the coated base paper (i.e., Comparative Example 1, ordinary offset paper) in the range of 200-700 nm; Figure 2 is a comparison chart of the complete diffuse reflectance curves of Example 2 of the present application and the coated base paper (i.e., Comparative Example 1, ordinary offset paper) in the range of 200-700 nm;

[0093] In summary, in order to better demonstrate the effectiveness of the anti-reflective eye protection functional paper of the present application in reducing the diffuse reflectance of harmful blue-violet light (400-480 nm) and ultraviolet light (mainly 315-400 nm), as shown in Figure 2, the eye protection functional paper produced in Examples 1-2 of the present application has a diffuse reflectance in the harmful blue-violet light region (400-480 nm) and ultraviolet light region (315-400 nm) that is significantly lower than that of the coated base paper (Comparative Example 1, ordinary offset paper), and the reflectance in the visible light region (500-700 nm) is basically unchanged (fluctuation less than 1%), thus the eye protection functional paper produced in the present application completely meets the reading habits of the human eye while reducing the reflectance of harmful blue-violet light and ultraviolet light, thereby ensuring the reading experience of the reader and the customer. Figures 1-2As shown, this invention used a Shimadzu UV-Vis spectrophotometer (UV-2600i) in integrating sphere mode to measure the diffuse reflectance of ordinary offset paper (Comparative Example 1) in the 200–700 nm wavelength range (the test wavelength interval is 1 nm for precise reading). First, the comparison of conventional performance in Table 1 shows that Examples 1–2 and Comparative Example 1 have no significant differences in conventional performance such as basis weight, D65 brightness, D65 fluorescence brightness, opacity, and smoothness. Second, based on the reflectance at specific wavelengths in Table 2… Figures 1-2 As can be seen from the full-wavelength reflectance curves, compared with uncoated ordinary offset paper (Comparative Example 1), the eye-protecting functional paper provided in Examples 1 and 2 of this invention significantly reduces the reflectance of harmful light rays in the ultraviolet region (primarily UVA, wavelength range of 315–400 nm) and the harmful blue-violet region (mainly 400–480 nm), while the reflectance of light in the comfortable reading wavelength range of 500–700 nm remains essentially unchanged. Therefore, the eye-protecting functional paper produced by this invention not only significantly reduces harmful light wavelengths to achieve myopia prevention and eye protection effects, but also ensures the comfort of the human eye in the visible light reading area.

[0094] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing an anti-reflective eye-protective functional paper, characterized by, It comprises the following steps: a) mixing bleached softwood kraft pulp, hardwood kraft pulp and poplar chemi-mechanical pulp, adding wet-end chemical auxiliaries, preparing pulp, and obtaining mixed pulp; the mass ratio of the bleached softwood kraft pulp, the hardwood kraft pulp and the poplar chemi-mechanical pulp is (28-32):(28-32):40; the beating degree of the bleached softwood kraft pulp in step a) is 300±25 mL, the beating degree of the hardwood kraft pulp is 325±25 mL, and the beating degree of the poplar chemi-mechanical pulp is 150±25 mL; b) sequentially performing wet paper forming, pre-drying, coating, post-drying and calender finishing on the mixed pulp obtained in step a) to obtain the anti-reflective eye protection functional paper; The coating formula used for coating comprises, by weight: 20-30 parts of nano cerium oxide, 20-30 parts of nano zinc oxide, 30-40 parts of inorganic nano blue light absorber, 15-30 parts of nano aluminum oxide, 1-5 parts of food-grade plant carbon black dispersion liquid, 1-4 parts of transparent plastic pigment dispersion liquid, 5-10 parts of water-based zinc stearate dispersion liquid, 10-40 parts of styrene-butadiene latex or acrylic latex, 5-15 parts of color fixing agent, 0.5-1 part of sodium carboxymethyl cellulose or polyvinyl alcohol, and 1-2 parts of dispersant.

2. The production method according to claim 1, characterized by, The wet-end chemical auxiliaries in step a) comprise: filler 300-350 kg / t paper, cationic starch 12-15 kg / t paper, retention aid 0.5-0.7 kg / t paper, bentonite 2.5-4.0 kg / t paper, sizing agent 15-18 kg / t paper, organic microparticles 0.35-0.55 kg / t paper, fixing agent 0.3-0.7 kg / t paper, and yellow dye 0.07-0.13 kg / t paper.

3. The preparation method according to claim 2, characterized in that, The filler is composed of light calcium carbonate and heavy calcium carbonate in a mass ratio of (1-3):1; the retention aid is cationic polyacrylamide; and the sizing agent is fast-acting alkyl ketene dimer emulsion.

4. The method of claim 1, wherein, The process of wet paper forming in step b) is specifically: The mixed slurry is pumped into a four-stage conical cleaner by a headbox pump for purification and deslagging, then into a degassing tank for degassing treatment, and then into a pressure screen for screening treatment, and then sent to a headbox for netting, to adjust the netting flow and control the paper sheet quantification to 70-90 g / m 2 After the wet paper sheet exits the netting part, it enters a press part for five-roller three-pressing-area compound pressing, and after being pressed to a dryness≥35%, it is subjected to post and front drying.

5. The method of claim 1, wherein, The temperature of pre-drying in step b) is 105-130°C, and the drying is performed until the paper sheet dryness is ≥92%.

6. The method of claim 1, wherein, The amount of the coating applied in step b) is 3 to 4 g / m 2 ; The coating pressure is controlled as: Nip pressure: 16-24 kN / m on the driving side and 16-24 kN / m on the operating side; Metering bar pressure: 0.6-1.2 bar on the upper roll and 0.6-1.2 bar on the lower roll.

7. The preparation method according to claim 1, characterized in that, The temperature of post-drying in step b) is 105-130°C, and the drying is performed until the paper sheet dryness is ≥93.5%.

8. The method of claim 1, wherein, The calender finishing temperature in step b) is 50-60°C, the first pressure is 870-890 KN / m, and the second pressure is 900-910 KN / m.

9. An anti-reflective eye-protecting functional paper, characterized by, The anti-reflective eye protection functional paper is prepared by the preparation method in any one of claims 1-8.

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