Anti-reflection eye protection functional paper and preparation method thereof

Abstract

The invention provides antireflection eye protection functional paper and a preparation method thereof. According to the preparation method, the coating with specific content components is adopted and matched with specific process steps, overall good interaction is achieved, compared with coated base paper, the diffuse reflection rates of the prepared anti-reflection eye-protecting functional paper are reduced by 10.07% at 315 nm and 6.77% at 400 nm respectively in a harmful blue-violet light area (400-480 nm) and an ultraviolet light area (especially UVA with the wavelength range of 315-400 nm), and the anti-reflection eye-protecting functional paper has the beneficial effects that the anti-reflection eye-protecting functional paper is good in anti-reflection effect and good in anti-reflection effect. The damage of harmful light to the retina of human eyes can be effectively reduced, and the effects of preventing myopia and protecting eyes are achieved; meanwhile, compared with coated raw paper, the reflectivity of the anti-reflection type eye protection functional paper is increased by 0.2% on the contrary within the 500-700 nm wave band comfortable for human eye reading, and the reading experience feeling of readers is further guaranteed.

Description

Technical Field

[0001] The invention relates to the technical field of papermaking technology, and more specifically, to an anti-reflection eye-protection functional paper and a preparation method thereof. Background Art

[0002] The problem of myopia among young people in my country remains severe, and it is showing a trend of younger age. In order to strengthen the prevention and control of myopia among children and adolescents and promote their visual health, the "Bright Action Work Plan for Myopia Prevention and Control among Children and Adolescents (2021-2025)" jointly issued by the General Office of the Ministry of Education and other 15 departments specifically proposed that in order to improve the visual environment of children and adolescents, combined with the specific requirements of the "Hygiene Requirements for Myopia Prevention and Control of Children and Adolescents' Learning Supplies", ensure that children and adolescents use textbooks, teaching materials, study magazines, homework books, examination papers, study newspapers, and preschool children's learning reading materials that meet hygiene requirements, and encourage the purchase and use of certified anti-myopia eye protection products. It is worth noting that among the above-mentioned eye protection paper products that are highly associated with children and adolescents, textbooks and teaching materials have attracted great attention from parents and publishers because of 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 based on the principle of eye injury. In general, visible blue-violet light and invisible ultraviolet light have higher energy and cause greater damage to the eyes. First of all, 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 photosensitive cells to lack nutrients, thereby causing vision damage, producing macular degeneration, squeezing and shrinking the lens, and causing myopia. At the same time, the degree of harm of blue-violet light to the eyes varies with age. Relevant studies have shown that blue-violet light causes the greatest damage to the eyes of children and adolescents. Secondly, ultraviolet light directly acts on the cornea and lens of the eye. The cornea and lens absorb most of the ultraviolet light, and the corneal curvature increases; at the same time, the lens of the eye accelerates aging, and the density of the liquid in the lens gradually increases. After the density increases, the refractive index of the lens increases (the lens is essentially a convex lens), resulting in an increase in focusing ability, and the degree of myopia of the eyes will also increase. Therefore, eye protection technology and paper products in the scientific sense should mainly revolve around optical regulation technology routes related to harmful blue-violet light and ultraviolet rays.

[0004] Children and adolescents are exposed to various light sources in their daily life and study. In addition to using different types of lights to assist reading, in most cases they read and use teaching materials in a regular daylight (natural light) environment, and the ultraviolet content in daylight is as high as 6%. Therefore, paper eye protection technology should work in various light source environments, rather than just relying on the improvement of the light source environment. It should start from the optical properties of the paper itself and effectively reduce the reflectivity of harmful short-wave blue-violet light and ultraviolet light (mainly UVA, wavelength range 320-400nm) on the surface of paper products, thereby reducing the harmful light reflected into the retina of the human eye, while not affecting the overall reading experience, and ultimately achieving the scientific anti-myopia eye protection effect.

[0005] However, the anti-myopia eye protection technology and paper products on the market are mainly based on non-fluorescent and color adjustment technology, that is, without adding fluorescent whitening agents, the optical properties of the paper (only focusing on D65 brightness) are simply adjusted to the range required by the national standard "Hygiene Requirements for Myopia Prevention and Control of Children and Adolescents' Learning Supplies" (GB 40070-2021), while meeting the basic requirements such as quantity, fluorescent brightness, and smoothness. Targeted preventive measures are lacking against harmful blue-violet light or even ultraviolet rays that can cause substantial damage to the eyes. Therefore, from the perspective of eye protection science and technology, they are not strictly eye protection functional paper products.

[0006] Therefore, there is an urgent need to develop an anti-reflective eye-protection paper product against harmful blue-violet light and ultraviolet rays, so as to reduce the damage to human eyes caused by harmful reflections in the two light zones during the use of paper products, thereby effectively preventing myopia and protecting the eyes. This has extremely important scientific and practical significance in the prevention and control of myopia and the national eye protection strategy. Summary of the invention

[0007] In view of this, the purpose of the present invention is to provide an anti-reflective eye protection functional paper and a preparation method thereof. An eye protection paper product is obtained by in-machine coating treatment based on a new anti-reflective functional coating. Compared with the coated base paper, the diffuse reflectance of the eye protection paper product in the harmful blue-violet light region (400-480nm) and the ultraviolet light region (especially UVA, with a wavelength range of 315-400nm) is reduced by 10.07% at 315nm and 6.77% at 400nm, respectively, which can effectively reduce the damage of harmful light to the retina of the human eye and achieve the effect of preventing myopia and protecting the eyes; at the same time, compared with the coated base paper, the reflectance of the eye protection paper product in the 500-700nm band where the human eye is comfortable to read is increased by 0.2%, further ensuring the reader's reading experience.

[0008] The present invention provides a method for preparing an anti-reflective eye protection functional paper, comprising the following steps:

[0009] a) mixing bleached softwood kraft pulp, hardwood kraft pulp and poplar chemimechanical pulp, adding wet end chemical auxiliary materials, and preparing the pulp to obtain a mixed pulp;

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

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

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

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

[0014] Preferably, the wet end chemical auxiliary materials in step a) include:

[0015] Filler 300-350kg / t paper, cationic starch 12-15kg / t paper, retention aid 0.5-0.7kg / t paper, bentonite 2.5-4.0kg / t paper, sizing agent 15-18kg / t paper, organic particles 0.35-0.55kg / t paper, fixing agent 0.3-0.7kg / t paper, yellow dye 0.07-0.13kg / 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 a fast-maturing alkyl ketene dimer emulsion.

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

[0018] The mixed pulp is sent to the first-stage four-stage conical slag remover for purification and slag removal through the slurry pump, and then enters the degassing tank for degassing treatment, and then enters the pressure screen for screening treatment, and then sent to the headbox for screen. The screen flow is adjusted to control the paper weight to 70-90g / m 2After the wet paper leaves the screen, it enters the pressing section for five-roller three-pressure zone composite pressing. After being pressed to a dryness of ≥35%, it is dried at the front and back ends.

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

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

[0021] Coating pressure control is:

[0022] Nip zone pressure: 16~24kN / m on the transmission side, 16~24kN / m on the operating side;

[0023] Metering rod pressure: upper roller is 0.6~1.2bar, lower roller is 0.6~1.2bar.

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

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

[0026] The present invention also provides an anti-reflection eye protection functional paper, which is prepared by the preparation method described in the above technical solution.

[0027] The invention provides an anti-reflection eye protection 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 mechanical pulp, adding wet end chemical auxiliary materials, and performing pulping to obtain a 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-reflection eye protection functional paper; the coating formula used for coating comprises, by weight, 20 to 30 parts of nano cerium oxide, 20 to 30 parts of nano zinc oxide, 30 to 40 parts of inorganic nano blue light absorber, 15 to 30 parts of nano aluminum oxide, 1 to 5 parts of food-grade plant carbon black dispersion, 1 to 4 parts of transparent plastic pigment dispersion, 5 to 10 parts of water-based zinc stearate dispersion, 10 to 40 parts of styrene-butadiene latex or acrylic latex, 5 to 15 parts of a color fixative, 0.5 to 1 part of sodium carboxymethyl cellulose or polyvinyl alcohol, and 1 to 2 parts of a dispersant. Compared with the prior art, the preparation method provided by the present invention adopts a coating with a specific content of components and cooperates with specific process steps to achieve overall better interaction. Compared with the coated base paper, the prepared anti-reflective eye protection functional paper has a diffuse reflectance of 10.07% at 315nm and 6.77% at 400nm in the harmful blue-violet light region (400-480nm) and the ultraviolet light region (especially UVA, with a wavelength range of 315-400nm), respectively, which can effectively reduce the damage of harmful light to the retina of the human eye and achieve the effect of preventing myopia and protecting the eyes; at the same time, compared with the coated base paper, the reflectance of the anti-reflective eye protection functional paper is increased by 0.2% in the 500-700nm band where the human eye is comfortable to read, further ensuring the reader's reading experience. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0029] Figure 2 It is a comparison chart of the complete diffuse reflectance curves of Example 2 of the present invention and the coated base paper (ie, Comparative Example 1, ordinary offset paper) in the range of 200 to 700 nm. DETAILED DESCRIPTION

[0030] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] The present invention provides a method for preparing an anti-reflective eye protection functional paper, comprising the following steps:

[0032] a) mixing bleached softwood kraft pulp, hardwood kraft pulp and poplar chemimechanical pulp, adding wet end chemical auxiliary materials, and preparing the pulp to obtain a mixed pulp;

[0033] b) subjecting the mixed slurry obtained in step a) to wet paper forming, pre-drying, coating, post-drying and calendering finishing in sequence to obtain anti-reflective eye protection functional paper;

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

[0035] The invention firstly mixes bleached softwood kraft pulp, hardwood kraft pulp and poplar chemimechanical pulp, then adds wet end chemical auxiliary materials to carry out pulping to obtain mixed pulp.

[0036] The present invention particularly selects bleached softwood kraft pulp (NBKP), bleached hardwood kraft pulp (LBKP) and self-produced Italian poplar chemimechanical pulp (APMP) as the main raw materials, and undergoes in-machine coating treatment. On the basis of ensuring the printability, glossiness, smoothness and other indicators of the paper, the paper products are further endowed with optical properties related to eye protection scientific elements through a coating with a specific formula; the present invention has no special restrictions on the sources of the above-mentioned bleached softwood kraft pulp, hardwood kraft pulp and poplar chemimechanical pulp, and commercially available products well known to those skilled in the art can be used.

[0037] In the present invention, the beating degree of the bleached softwood kraft pulp (measured in Canadian freeness) is preferably 300±25mL, the beating degree of the hardwood kraft pulp is preferably 325±25mL, and the beating degree of the poplar chemimechanical pulp is preferably 150±25mL; the raw materials after being pulped separately are mixed.

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

[0039] In the present invention, the wet end chemical auxiliary materials (addition amount is calculated in kg / t paper) preferably include:

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

[0041] More preferably, it is composed of the following components:

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

[0043] The present invention has no special restrictions on the sources of the raw materials in the wet end chemical auxiliary materials, and commercially available products well known to those skilled in the art can be used.

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

[0045] After obtaining the mixed slurry, the present invention sequentially performs wet paper forming, pre-drying, coating, post-drying and calendering finishing on the mixed slurry to obtain anti-reflective eye protection functional paper;

[0046] In the present invention, the wet paper forming process is preferably specifically as follows:

[0047] The mixed pulp is sent to the first-stage four-stage conical slag remover for purification and slag removal through the slurry pump, and then enters the degassing tank for degassing treatment, and then enters the pressure screen for screening treatment, and then sent to the headbox for screen. The screen flow is adjusted to control the paper weight to 70-90g / m 2 ; After the wet paper leaves the screen section, it enters the pressing section for five-roller three-pressure zone composite pressing, and after pressing to a dryness ≥ 35%, it is dried before and after. The above steps can be implemented using equipment well known to those skilled in the art, with the purpose of obtaining formed wet paper. On this basis, the existing technology can obtain ordinary offset paper through drying and other processes.

[0048] In the present invention, the pre-drying temperature is preferably 105-130° C., and the paper sheet is dried to a dryness of preferably ≥ 92%.

[0049] In the present invention, the coating (anti-reflective eye protection coating) 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, 1-4 parts of transparent plastic pigment dispersion, 5-10 parts of water-based zinc stearate dispersion, 10-40 parts of styrene-butadiene latex or acrylic latex, 5-15 parts of color fixative, 0.5-1 part of sodium carboxymethyl cellulose or polyvinyl alcohol, and 1-2 parts of dispersant;

[0050] It is preferably composed of the following components:

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

[0052] The present invention has no particular limitation on the sources of the above-mentioned raw material components, and commercially available products known to those skilled in the art may be used.

[0053] In the present invention, the coating used for coating is preferably coated through an aqueous dispersion system; the aqueous dispersion system is preferably a coating starch aqueous dispersion with a mass fraction of 10% diluted with water; the present invention performs a coating process by compounding the raw material components in the above-mentioned anti-reflective eye protection coating into the surface sizing starch, and at the same time ensures the uniformity of sizing and prevents uneven sizing; the starch is preferably native cassava starch.

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

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

[0056] In the present invention, the inorganic nano blue light absorber can accurately absorb ultraviolet rays and harmful blue light in the 320-460nm band, effectively protect the eyes from blue light damage, and has no significant absorption effect on 440-780nm visible light; the inorganic nano blue light absorber preferably selects appropriate inorganic nano materials, such as zinc oxide, silicon dioxide, aluminum oxide, zirconium oxide, titanium oxide, etc. as a substrate and synthesizes 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, it is preferably also coated with a layer of organic or inorganic material, or a specific functional group is introduced for modification (surface modification). The appearance of the final material is light yellow, which has little effect on the transparency and color of the product.

[0057] In the present invention, the particle size of the nano-alumina (Al2O3) is preferably 20 to 200 nm, more preferably 20 to 100 nm, and even more preferably 30 to 50 nm.

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

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

[0060] In the present invention, the solid content of the aqueous zinc stearate dispersion is preferably 30-40%, and the particle size is preferably 400-600 nm; zinc stearate has a certain ultraviolet absorption ability. Although the absorption effect is weak, it can protect the eye protection functional paper with a high proportion of chemical mechanical pulp from damage by ultraviolet rays to a certain extent and delay the aging of the paper.

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

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

[0063] In the present invention, the coating amount is preferably 3 to 4 g / m 2 ;

[0064] The coating pressure control is preferably:

[0065] Nip pressure: preferably 16-24 kN / m on the transmission side and 16-24 kN / m on the operating side;

[0066] The pressure of the metering rod: the upper roller is preferably 0.6-1.2 bar, and the lower roller is preferably 0.6-1.2 bar.

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

[0068] The present invention has no special restrictions on the devices for implementing the pre-drying and post-drying, and any drying cylinder well known to those skilled in the art may be used.

[0069] In the present invention, the paper sheets obtained after post-drying are subjected to calendering treatment, and then the paper sheets are wound up after finishing, so as to obtain anti-reflection eye-protection functional paper with good surface flatness and good printing performance.

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

[0071] The present invention also provides an anti-reflection eye protection functional paper, which is prepared by the preparation method described in the above technical solution.

[0072] The present invention provides an anti-reflective and environmentally friendly eye-protection functional paper based on a novel functional coating material for harmful light, which is prepared by the preparation method described in the above technical solution; and has the following beneficial effects:

[0073] (1) Compared with conventional offset paper, the anti-reflective eye-protection functional paper prepared by the present invention has a lower whiteness, is not glaring, has a soft visual effect, and has excellent printing effect; (2) Compared with conventional eye-protection paper products on the market, the anti-reflective eye-protection functional paper prepared by the present invention has reduced reflected light, especially around the harmful blue-violet light (400-480nm) and ultraviolet light (mainly 315-400nm) that actually damage the human eye. The directional functional coating design is carried out, and for the first time, the reflectivity of harmful light in the entire ultraviolet and visible light region on the paper surface is systematically and comprehensively reduced by as much as 20-40%, thereby reducing the harmful light received by the human eye retina, and has the scientific effect of preventing myopia and protecting the eyes; the main user groups of this product are children and adolescents or high-end customers who have special requirements for the eye-protection effect of the product, specifically in the field of teaching materials paper that children and adolescents use frequently and read for a long time, and it has extremely high added value and broad market prospects.

[0074] The invention provides an anti-reflection eye protection 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 mechanical pulp, adding wet end chemical auxiliary materials, and performing pulping to obtain a 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-reflection eye protection functional paper; the coating formula used for coating comprises, by weight, 20 to 30 parts of nano cerium oxide, 20 to 30 parts of nano zinc oxide, 30 to 40 parts of inorganic nano blue light absorber, 15 to 30 parts of nano aluminum oxide, 1 to 5 parts of food-grade plant carbon black dispersion, 1 to 4 parts of transparent plastic pigment dispersion, 5 to 10 parts of water-based zinc stearate dispersion, 10 to 40 parts of styrene-butadiene latex or acrylic latex, 5 to 15 parts of a color fixative, 0.5 to 1 part of sodium carboxymethyl cellulose or polyvinyl alcohol, and 1 to 2 parts of a dispersant. Compared with the prior art, the preparation method provided by the present invention adopts a coating with a specific content of components and cooperates with specific process steps to achieve overall better interaction. Compared with the coated base paper, the prepared anti-reflective eye protection functional paper has a diffuse reflectance of 10.07% at 315nm and 6.77% at 400nm in the harmful blue-violet light region (400-480nm) and the ultraviolet light region (especially UVA, with a wavelength range of 315-400nm), respectively, which can effectively reduce the damage of harmful light to the retina of the human eye and achieve the effect of preventing myopia and protecting the eyes; at the same time, compared with the coated base paper, the reflectance of the anti-reflective eye protection functional paper is increased by 0.2% in the 500-700nm band where the human eye is comfortable to read, further ensuring the reader's reading experience.

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

[0076] Example 1

[0077] Firstly, three kinds of pulps including bleached softwood kraft pulp (NBKP, beating degree 300ml), hardwood kraft pulp (LBKP, beating degree 325ml) and poplar chemimechanical pulp (APMP, beating degree 150ml) were mixed in the ratio of 30wt%:30wt%:40wt%. Then, 300kg / t paper of calcium carbonate filler and other wet-end chemical auxiliary materials were added at a ratio of light calcium to heavy calcium = 2:1 (mass ratio). The specific addition of wet-end chemical auxiliary materials is as follows: 15kg / t paper of cationic starch, 0.6kg / t paper of retention aid cationic polyacrylamide, 4.0kg / t paper of bentonite, 16kg / t paper of sizing agent AKD (fast-maturing alkyl ketene dimer emulsion), 0.4kg / t paper of organic particles, 0.4kg / t paper of fixative, and 0.08kg / t paper of yellow dye. The mixed pulp was sent to the first-stage four-stage conical slag remover for purification and slag removal through the pulp flushing pump, and then entered the degassing tank for degassing treatment, and then entered the pressure screen for screening treatment, and then sent to the headbox for online, and the online flow was adjusted to control the paper sheet basis weight to 80g / m 2 ; After the wet paper leaves the screen, it enters the pressing section for five-roller three-pressure zone composite pressing. After being pressed to a dryness of ≥39%, it enters the pre-drying section; the surface temperature of the drying cylinder is controlled at 105-130°C to dry the paper until the dryness of the paper is ≥92%; it enters the size press for in-machine coating treatment: 10wt% coating starch diluted with water is used as the aqueous dispersion system, and 20 weight parts of nano cerium oxide (CeO2), 30 weight parts of rod-shaped nano zinc oxide (ZnO), 35 weight parts of inorganic nano blue light absorber A1, 15 weight parts of nano aluminum oxide (Al2O3), 1 weight part of food-grade plant carbon black dispersion, 4 weight parts of transparent plastic pigment B dispersion, 5 weight parts of aqueous zinc stearate dispersion, 30 weight parts of styrene-butadiene latex, 10 weight parts of color fixative, 0.8 weight parts of sodium carboxymethyl cellulose (CMC), and 1.5 weight parts of dispersant are added; the coating amount is 3-4g / m 2 ; The coating pressure is controlled as follows: pressure in the pressure zone: 20 kN / m on the transmission side and 20 kN / m on the operating side; pressure on the metering rod: 1 bar on the upper roller and 1 bar on the lower roller; then the wet paper sheets that have been deeply treated by coating are discharged from the surface sizing machine and further subjected to post-drying, the temperature of the drying cylinder is controlled at 105-130°C, and the dryness of the paper sheets discharged from the post-drying section is ≥93.5%; the paper sheets entering from the post-drying section enter the calendering section and are calendered, the calendering temperature is controlled at 50-60°C, the first press is 880 kN / m, and the second press is 900 kN / m; after calendering, the paper is rolled up to obtain anti-reflective eye protection functional paper with good surface flatness and good printing performance.

[0078] Figure 1The diffuse reflection curves of Example 1 of the present invention and Comparative Example 1, i.e., ordinary offset paper, in the full band of ultraviolet and visible light of 200-700 nm are compared; the reflectivity values ​​at typical wavelengths of different bands are shown in Table 2 below. Figure 1 It can be seen from the results that compared with uncoated ordinary offset paper, the eye protection functional paper in Example 1 of the present invention has significantly reduced reflectivity of eye-damaging light in the ultraviolet light region (focusing on UVA, with a wavelength range of 315-400nm) and harmful blue-violet light region (mainly 400-480nm), while the reflectivity of light with a wavelength of 500-700nm, which is comfortable for human eyes to read, remains basically unchanged; therefore, the anti-reflective eye protection functional paper provided by the present invention not only protects the eyes and prevents myopia, but also ensures reading comfort.

[0079] Example 2

[0080] In order to better illustrate the effect of the anti-reflective coating material on the eye protection functional paper, in Example 2 of the present invention, all the process sections before the in-machine coating remain the same, so they are not described repeatedly here. The difference is that the formula of the anti-reflective coating material used for producing the eye protection functional paper in Example 2 is different; in the in-machine coating stage, Example 2 uses 10wt% of coating starch as the aqueous dispersion system, adds 30 weight parts of nano cerium oxide (CeO2), 20 weight parts of rod-shaped nano zinc oxide (ZnO), 30 weight parts of inorganic nano blue light absorber A2, 20 weight parts of nano aluminum oxide (Al2O3), 1 weight part of food-grade plant carbon black dispersion, 4 weight parts of transparent plastic pigment B dispersion, 5 weight parts of aqueous zinc stearate, 30 weight parts of acrylic latex, 10 weight parts of fixing agent, 0.8 weight parts of polyvinyl alcohol (PVA), and 1.5 weight parts of dispersant; the coating amount is 3-4g / m 2 ; The coating pressure is controlled as follows: pressure in the pressure zone: 20 kN / m on the transmission side and 20 kN / m on the operating side; pressure on the metering rod: 1 bar on the upper roller and 1 bar on the lower roller; then the wet paper sheets that have been deeply treated by coating are discharged from the surface sizing machine and further subjected to post-drying, the temperature of the drying cylinder is controlled at 105-130°C, and the dryness of the paper sheets discharged from the post-drying section is ≥93.5%; the paper sheets entering from the post-drying section enter the calendering section and are calendered, the calendering temperature is controlled at 50-60°C, the first press is 880 kN / m, and the second press is 900 kN / m; after calendering, the paper is rolled up to obtain anti-reflective eye protection functional paper with good surface flatness and good printing performance.

[0081] Figure 2 The diffuse reflection curves of Example 2 of the present invention and Comparative Example 1, i.e., ordinary offset paper, in the full band of ultraviolet visible light of 200-700 nm are compared; the reflectivity values ​​at typical wavelengths of different bands are shown in Table 2 below. Figure 2It can be seen from the results that compared with uncoated ordinary offset paper, the eye protection functional paper in Example 2 of the present invention has a significantly reduced reflectivity to eye-damaging light in the ultraviolet light region (focusing on UVA, with a wavelength range of 315-400nm) and harmful blue-violet light region (mainly 400-480nm), while the reflectivity of light with a wavelength of 500-700nm, which is comfortable for human eyes to read, remains basically unchanged; therefore, the anti-reflective eye protection functional paper provided by the present invention not only protects the eyes and prevents myopia, but also ensures reading comfort.

[0082] Comparative Example 1

[0083] Firstly, three kinds of pulps including bleached softwood kraft pulp (NBKP, beating degree 300ml), hardwood kraft pulp (LBKP, beating degree 325ml) and poplar chemimechanical pulp (APMP, beating degree 150ml) were mixed in the ratio of 30wt%:30wt%:40wt%. Then, 300kg / t paper of calcium carbonate filler and other wet-end chemical auxiliary materials were added at a ratio of light calcium to heavy calcium = 2:1 (mass ratio). The specific addition of wet-end chemical auxiliary materials is as follows: 15kg / t paper of cationic starch, 0.6kg / t paper of retention aid cationic polyacrylamide, 4.0kg / t paper of bentonite, 16kg / t paper of sizing agent AKD (fast-maturing alkyl ketene dimer emulsion), 0.4kg / t paper of organic particles, 0.4kg / t paper of fixative, and 0.08kg / t paper of yellow dye. The mixed pulp was sent to the first-stage four-stage conical slag remover for purification and slag removal through the pulp flushing pump, and then entered the degassing tank for degassing treatment, and then entered the pressure screen for screening treatment, and then sent to the headbox for online, and the online flow was adjusted to control the paper sheet basis weight to 80g / m 2 ; After the wet paper leaves the screen section, it enters the pressing section for five-roller three-pressure zone composite pressing, and enters the pre-drying section after being pressed to a dryness ≥39%; the surface temperature of the drying cylinder is controlled at 105-130°C to dry the paper until the dryness of the paper is ≥92%; after post-drying, the drying cylinder temperature is controlled at 105-130°C, and the dryness of the paper leaves the post-drying section is ≥93.5%; the paper leaves entering the post-drying section enter the calendering section, and the calendering temperature is controlled at 50-60°C, the first press is pressurized at 880KN / m, and the second press is pressurized at 900KN / m; after calendering, the paper is rolled up to obtain ordinary offset paper whose raw material structure and manufacturing process are consistent with the eye protection functional paper in Example 1.

[0084] Performance Test:

[0085] The present invention tests conventional indicators of the eye protection functional paper such as basis weight, D65 brightness, D65 fluorescence brightness, opacity, smoothness and other conventional properties, and the results are shown in Table 1.

[0086] Table 1 General performance data

[0087]

[0088]

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

[0090] Table 2 Reflectivity data

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

[0092] As can be seen from Table 2, the anti-reflection eye protection functional paper produced in Examples 1 to 2 of the present invention has a significantly lower reflectance value for harmful blue-violet light (usually with a wavelength of 400 to 480 nm) and ultraviolet light (mainly UVA, i.e., low-frequency long-wave ultraviolet light with a wavelength of 315 to 400 nm) than conventional offset paper (Comparative Example 1, coated base paper). Specifically, at a typical wavelength such as 315 nm in the ultraviolet region, compared with the coated base paper in Comparative Example 1, it is reduced by about 10%; at 400 nm, it is reduced by about 6 to 7%; at 420 nm in the typical wavelength region of harmful blue-violet light, compared with the coated base paper in Comparative Example 1, it is reduced by 4 to 5%; however, the eye protection paper of the present invention has a relatively comfortable visible light band of 500 to 700 nm for human eyes to read (taking the reflectance value at 600 nm as an example, the complete full-band reflectance curve is shown in the attached figure for details). Figures 1-2 ,in, Figure 1 It is a complete comparison chart of diffuse reflectance curves of Example 1 of the present invention and coated base paper (i.e., Comparative Example 1, ordinary offset paper) in the range of 200 to 700 nm; Figure 2 The complete diffuse reflectance curve comparison diagram 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 is basically unchanged (fluctuation is less than 1%). Therefore, the eye protection functional paper produced by the present invention fully conforms to the reading habits of the human eye while reducing the reflectance of eye-damaging light such as ultraviolet light and harmful blue-violet light, thereby ensuring the reading experience of readers and customers.

[0093] In summary, in order to better demonstrate the effectiveness of the anti-reflective eye protection functional paper in the present invention in reducing the diffuse reflectivity of harmful blue-violet light (400-480nm) and ultraviolet light (mainly 315-400nm), as Figures 1-2As shown, the present invention uses Shimadzu UV-Vis spectrophotometer (UV-2600i) in the integrating sphere mode to measure the diffuse reflectance of ordinary offset paper (Comparative Example 1) in the 200-700nm band (the test wavelength interval is 1nm); first, from the comparison of the conventional properties in Table 1, it can be seen that there is no obvious difference between Examples 1-2 and Comparative Example 1 in terms of conventional properties such as quantitative, D65 brightness, D65 fluorescence brightness, opacity, and smoothness; secondly, according to the reflectance and Figures 1-2 It can be seen from the full wavelength reflectivity curve that, compared with the uncoated ordinary offset paper, i.e., comparative example 1, the reflectivity of the eye protection functional paper provided by examples 1 to 2 of the present invention to the eye-damaging light in the ultraviolet light region (focusing on UVA, with a wavelength range of 315 to 400nm) and the harmful blue-violet light region (mainly 400 to 480nm) is significantly reduced, while the reflectivity of the light with a wavelength of 500 to 700nm, which is comfortable for human eyes to read, remains basically unchanged. Therefore, the eye protection functional paper produced by the present invention not only significantly reduces the harmful light band to achieve the effect of preventing myopia and protecting the eyes, but also ensures the comfort of the human eye in the visible light reading region.

[0094] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be 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 present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing anti-reflective eye protection functional paper, characterized in that: The following steps are involved: a) mixing bleached softwood kraft pulp, hardwood kraft pulp and poplar chemimechanical pulp, adding wet end chemical auxiliary materials, and preparing the pulp to obtain a mixed pulp; b) subjecting the mixed slurry obtained in step a) to wet paper forming, pre-drying, coating, post-drying and calendering finishing in sequence to obtain anti-reflective eye protection functional paper; The coating formula used for coating comprises, by weight, 20 to 30 parts of nano cerium oxide, 20 to 30 parts of nano zinc oxide, 30 to 40 parts of inorganic nano blue light absorber, 15 to 30 parts of nano aluminum oxide, 1 to 5 parts of food-grade plant carbon black dispersion, 1 to 4 parts of transparent plastic pigment dispersion, 5 to 10 parts of water-based zinc stearate dispersion, 10 to 40 parts of styrene-butadiene latex or acrylic latex, 5 to 15 parts of color fixing agent, 0.5 to 1 part of sodium carboxymethyl cellulose or polyvinyl alcohol, and 1 to 2 parts of dispersant.

2. The preparation method according to claim 1, characterized in that: 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 chemimechanical pulp is 150±25 mL; The mass ratio of the bleached softwood kraft pulp, the hardwood kraft pulp and the poplar chemimechanical pulp is (28-32): (28-32):

40.

3. The preparation method according to claim 1, characterized in that: The wet end chemical auxiliary materials in step a) include: Filler 300-350kg / t paper, cationic starch 12-15kg / t paper, retention aid 0.5-0.7kg / t paper, bentonite 2.5-4.0kg / t paper, sizing agent 15-18kg / t paper, organic particles 0.35-0.55kg / t paper, fixing agent 0.3-0.7kg / t paper, yellow dye 0.07-0.13kg / t paper.

4. The preparation method according to claim 3, 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 a fast-maturing alkyl ketene dimer emulsion.

5. The preparation method according to claim 1, characterized in that: The process of wet paper forming in step b) is specifically as follows: The mixed pulp is sent to the first-stage four-stage conical slag remover for purification and slag removal through the slurry pump, and then enters the degassing tank for degassing treatment, and then enters the pressure screen for screening treatment, and then sent to the headbox for screen. The screen flow is adjusted to control the paper weight to 70-90g / m 2 After the wet paper leaves the screen, it enters the pressing section for five-roller three-pressure zone composite pressing. After being pressed to a dryness of ≥35%, it is dried at the front and back ends.

6. The preparation method according to claim 1, characterized in that: The pre-drying temperature in step b) is 105-130° C., and the paper is dried to a dryness of ≥92%.

7. The preparation method according to claim 1, characterized in that: The amount of coating applied in step b) is 3-4 g / m 2 ; Coating pressure control is: Nip zone pressure: 16~24kN / m on the transmission side, 16~24kN / m on the operating side; Metering rod pressure: upper roller is 0.6~1.2bar, lower roller is 0.6~1.2bar.

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

9. The preparation method according to claim 1, characterized in that: The calendering temperature of the calendering finishing in step b) is 50-60° C., the first press is 870-890 KN / m, and the second press is 900-910 KN / m.

10. An anti-reflective eye protection functional paper, characterized in that: The preparation method is described in any one of claims 1 to 9.

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