Fluorescent whitening composition as well as preparation method and application thereof

Abstract

The invention relates to the field of fluorescent whitening, and discloses a fluorescent whitening composition and a preparation method and application thereof, the fluorescent whitening composition comprises the following components by weight: 30-45 parts of an acrylate emulsion, 5-12 parts of a fluorescent whitening agent, 1-5 parts of a modified additive, and 10-25 parts of deionized water; the fluorescent whitening agent is an aminated nano titanium dioxide grafted modified fluorescent parent, and the modified fluorescent parent is prepared by carrying out a first-step nucleophilic substitution reaction on cyanuric chloride and p-aminobenzene sulfonic acid and then carrying out a second-step nucleophilic substitution reaction on the obtained product and a fluorescent parent 4, 4-diaminostilbene-2, 2-disulfonic acid; according to the invention, the fluorescent whitening agent and the modified additive are added, so that the whiteness of the paper can be improved, the effect of inhibiting the yellowing of the paper is obvious, and the paper is not prone to yellowing. And the tensile strength, the tearability, the water resistance and the aging resistance of the paper can be effectively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of fluorescent whitening, and specifically relates to a fluorescent whitening composition and a preparation method and application thereof. Background Art

[0002] Fluorescent whitening agent is an organic compound that can absorb ultraviolet light and stimulate blue or blue-violet fluorescence. The substance adsorbed with fluorescent whitening agent can, on the one hand, reflect the visible light irradiated on the object, and at the same time, convert the absorbed invisible ultraviolet light (wavelength of 300-400nm) into blue or blue-violet visible light and emit it. Since blue and yellow are complementary colors, the yellow color in the matrix of the object is eliminated, making it appear white and bright; on the other hand, it increases the emissivity of the object to light, and the intensity of the emitted light exceeds the intensity of the original visible light projected on the treated object, so people see that the whiteness of the object has increased with their eyes, thereby achieving the purpose of whitening.

[0003] The promotion of high-yield pulp is of great significance to alleviate the problems of wood pulp resource shortage and environmental pollution that the pulp and paper industry has long faced. High-yield pulp not only has a high pulping yield (up to 80% to 95%) and low pollution, but also has high paper bulk and opacity, and has broad application prospects in the pulp and paper industry. However, high-yield pulp has a high lignin content and is prone to photo-yellowing, which limits its application in high-quality paper products. The use of fluorescent brighteners can effectively alleviate this problem. Among them, diphenylethylene fluorescent brighteners are the most widely used fluorescent brighteners in the papermaking industry. They have the advantages of significant whitening effect, good ultraviolet absorption performance, and high fluorescence quantum yield. However, they also have disadvantages such as poor water solubility, serious photo-yellowing, easy loss of coating, and poor fiber bonding ability. After being used for paper coating, the heat aging resistance and ultraviolet aging resistance of paper need to be further improved. Summary of the invention

[0004] In order to solve the deficiencies mentioned in the above background technology, the purpose of the present invention is to provide a fluorescent whitening composition and its preparation method and application. By adding a fluorescent whitening agent and a modifying additive, the whiteness of paper can be improved, the yellowing of paper can be inhibited significantly, and the tensile strength, tear resistance, water resistance and aging resistance of paper can be effectively improved.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] A fluorescent whitening composition comprises the following components in parts by weight: 30 to 45 parts of acrylic emulsion, 5 to 12 parts of fluorescent whitening agent, 1 to 5 parts of modified additive, and 10 to 25 parts of deionized water;

[0007] The fluorescent brightener is an amination-modified fluorescent matrix grafted with nano-titanium dioxide. The modified fluorescent matrix is ​​prepared by a first step nucleophilic substitution reaction between cyanuric chloride and p-aminobenzenesulfonic acid and a second step nucleophilic substitution reaction with the fluorescent matrix 4,4-diaminostilbene-2,2-disulfonic acid. The structural formula of the modified fluorescent matrix is ​​as follows:

[0008]

[0009] The modified additive is prepared by covalently grafting graphene oxide onto the surface of nano silicon dioxide and grafting tert-butyl glycidyl carbonate.

[0010] Preferably, the preparation method of the fluorescent whitening agent comprises the following steps:

[0011] A. Take cyanuric chloride and deionized water in a reactor, place them in an ice water bath and stir them evenly, dissolve p-aminobenzenesulfonic acid in deionized water and add them to the reactor, adjust the pH value of the system to 6, control the reaction temperature to 0-5°C, react for 2-3h, and obtain the initial product;

[0012] B. Dissolve 4,4-diaminostilbene-2,2-disulfonic acid and anhydrous potassium carbonate in deionized water, adjust the pH value of the system to 7-8 to obtain a mixed solution, add the mixed solution to the initial product, continue to adjust the pH value of the system to 7-8, and then place it at 45-60°C for 2-4h to obtain a modified fluorescent matrix;

[0013] C. Ultrasonic dispersion of nano-titanium dioxide in a mixture of ethanol and deionized water, dropwise addition of glacial acetic acid to adjust the pH value of the system to 4-5, raise the temperature to 70-85°C, slowly dropwise addition of 3-aminopropyltriethoxysilane, react for 6-8h after the addition is completed, centrifuge, wash, and dry to obtain amino-modified nano-titanium dioxide;

[0014] D. Add amino nano-titanium dioxide to the modified fluorescent matrix, raise the temperature to 80-95°C, adjust the pH value of the system to 9-10, react for 2-4 hours, filter, wash and dry to obtain a fluorescent whitening agent.

[0015] Preferably, the molar ratio of cyanuric chloride, p-aminobenzenesulfonic acid, 4,4-diaminobenzene-2,2-disulfonic acid, anhydrous potassium carbonate and amino nano-titanium dioxide is 1:1.05-1.5:0.5-0.8:0.5-0.8:0.6-1.

[0016] Preferably, the preparation method of the modified additive comprises the following steps:

[0017] (1) taking nano-silica and dispersing it in anhydrous ethanol by ultrasonic, adding γ-glycidyloxypropyltrimethoxysilane, passing nitrogen gas under reflux for 2 to 4 hours, cooling to room temperature after the reaction is completed, washing and drying, and preparing modified nano-silica;

[0018] (2) ultrasonically dispersing graphene oxide in deionized water to obtain a dispersion, dissolving lysine in deionized water, adjusting the pH value of the system to 7-8 to obtain a mixed solution, mixing the dispersion with the mixed solution and ultrasonically dispersing the mixture, reacting at 25-40° C. for 18-24 h, and washing and drying after the reaction to obtain modified graphene oxide;

[0019] (3) taking modified graphene oxide and modified nano-silica into a reactor, adding deionized water for ultrasonic dispersion, and then reacting at 40 to 50° C. for 16 to 24 hours. After the reaction is completed, washing and drying are performed to prepare a composite additive;

[0020] (4) The composite additive is dissolved in butyl acetate and ultrasonically dispersed, triphenylphosphine is added, the temperature is raised to 90-120° C., and then tert-butyl glycidyl carbonate is added to react for 8-12 hours. After the reaction is completed, the modified additive is prepared by filtration, washing, and drying.

[0021] Preferably, in step (2), the ratio of graphene oxide to lysine is 1:3-5.

[0022] Preferably, in step (3), the mass ratio of modified graphene oxide to modified nano-silicon dioxide is 2 to 3:1.

[0023] Preferably, in step (4), the mass ratio of the composite additive to tert-butyl glycidyl carbonate is 1:4-8.

[0024] The preparation method of the fluorescent whitening composition as described above comprises the following steps: stirring and mixing acrylate emulsion, fluorescent whitening agent, modifying additive and deionized water at a stirring speed of 60 to 120 rpm for 0.5 to 1 hour, and obtaining the fluorescent whitening composition after the stirring is completed.

[0025] An application of the fluorescent whitening composition as described above in paper, wherein the fluorescent whitening composition is used for coating the surface of paper.

[0026] Beneficial effects of the present invention:

[0027] The invention uses cyanuric chloride and p-aminobenzenesulfonic acid as raw materials, 4,4-diaminostilbene-2,2-disulfonic acid as a fluorescent matrix, and then connects the aminated nano titanium dioxide with the modified fluorescent matrix through nucleophilic substitution to prepare a fluorescent whitening agent. The water solubility of the fluorescent whitening agent can be increased by introducing a plurality of sulfonic acid groups, and the bonding strength between the fluorescent whitening agent and paper fibers can be improved. The nano titanium dioxide latex particles contained in the fluorescent whitening agent are uniformly adsorbed on the surface of the paper, effectively filling the fiber gaps, making the bonding between the fibers tighter, and effectively improving the mechanical properties of the paper. At the same time, the water absorption capacity of a single fiber is reduced, and the water resistance of the paper is improved. The nano titanium dioxide has high whiteness and strong tinting power. After being coated on the surface of the paper, it can play a role of physical whitening, and significantly improves the whiteness of the paper. In addition, the nano titanium dioxide has the effects of antibacterial, deodorizing, mildew-proofing, etc., and the introduction of the nano titanium dioxide particles can enable the fluorescent whitening agent to play a role of shielding ultraviolet rays while playing an optical whitening role, and effectively inhibit the yellowing of the paper caused by ultraviolet light.

[0028] The present invention utilizes γ-glycidyloxypropyltrimethoxysilane to modify nano silicon dioxide particles so that the surface thereof has epoxy groups, and then utilizes lysine of diamine structure as a bridge to covalently graft graphene oxide on the surface of nano silicon dioxide to prepare composite additives, which can not only increase the interlayer spacing of graphene oxide, but also be beneficial to the dispersion of graphene oxide, and can also increase the contact area of ​​graphene oxide with the matrix, improve the compatibility between the composite additive and the matrix, and the addition of the composite additive can give the paper excellent mechanical properties and thermal insulation properties, and in addition utilizes the carboxyl group on the surface of the composite additive to react with the epoxy group on the surface of tert-carbonic acid glycidyl ester, thereby introducing tert-carbonic acid hydrophobic groups on the surface of the composite additive, and improving the water resistance of the paper, and the acrylic emulsion added at the same time has the effect of bonding and film formation, and can adjust the tensile strength of the paper, enhance the bearing capacity of the paper, and prevent the paper from being broken due to uneven tension during use. The fluorescent whitening composition prepared by the present invention can improve the whiteness of the paper, and has a significant effect of inhibiting the yellowing of the paper, and can effectively improve the tensile strength, tearing degree, water resistance and aging resistance of the paper. DETAILED DESCRIPTION

[0029] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in 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.

[0030] Embodiment 1 A method for preparing a fluorescent whitening agent comprises the following steps:

[0031] A. Take 5.9g of cyanuric chloride and 20mL of deionized water in a reactor, place in an ice water bath and stir evenly, dissolve 6.2g of p-aminobenzenesulfonic acid in deionized water and add to the reactor, adjust the pH value of the system to 6, control the reaction temperature to 4°C, react for 3h, and obtain the initial product;

[0032] B. Dissolve 6.6 g of 4,4-diaminostilbene-2,2-disulfonic acid and 6.2 g of anhydrous potassium carbonate in deionized water, adjust the pH value of the system to 7, and obtain a mixed solution. Add the mixed solution to the initial product, continue to adjust the pH value of the system to 7, and then place it at 45-60° C. for 2-4 hours to obtain a modified fluorescent matrix.

[0033] C. Take 4g of nano-titanium dioxide and ultrasonically disperse it in a mixture of 80mL of ethanol and 20mL of deionized water, add glacial acetic acid to adjust the pH value of the system to 5, raise the temperature to 80°C, slowly add 5.2g of 3-aminopropyltriethoxysilane, and react for 7h after the addition is completed. After the reaction is completed, centrifuge, wash and dry to obtain amino-modified nano-titanium dioxide;

[0034] D. Add 7.8 g of amino-modified nano-titanium dioxide to the modified fluorescent matrix, raise the temperature to 95°C, adjust the pH value of the system to 9, react for 4 hours, filter, wash and dry to obtain a fluorescent whitening agent.

[0035] Embodiment 2 A method for preparing a modified additive comprises the following steps:

[0036] (1) 1 g of nano-silica was ultrasonically dispersed in 50 mL of anhydrous ethanol, 1.4 g of γ-glycidyloxypropyltrimethoxysilane was added, and nitrogen was refluxed for 2 h. After the reaction was completed, the reaction was cooled to room temperature, washed, and dried to prepare modified nano-silica;

[0037] (2) 0.8 g of graphene oxide was ultrasonically dispersed in 150 mL of deionized water to obtain a dispersion, 3.2 g of lysine was dissolved in deionized water, 1 mL of 4.2 mg / mL sodium hydroxide solution was added to obtain a mixed solution, the dispersion and the mixed solution were mixed and ultrasonically dispersed, and the mixture was placed at 30° C. for reaction for 24 h. After the reaction was completed, the modified graphene oxide was prepared by washing and drying;

[0038] (3) taking 1 g of modified graphene oxide and 0.5 g of modified nano-silica into a reactor, adding 100 mL of deionized water for ultrasonic dispersion, and then reacting at 45 ° C for 18 h. After the reaction is completed, washing and drying are performed to prepare a composite additive;

[0039] (4) 1 g of the composite additive was dissolved in 40 mL of butyl acetate and dispersed by ultrasonication, 0.004 g of triphenylphosphine was added, the temperature was raised to 100° C., and then 4.7 g of tert-butyl glycidyl carbonate was added to react for 12 h. After the reaction was completed, the modified additive was prepared by filtration, washing, and drying.

[0040] Example 3 A fluorescent whitening composition comprises the following components in parts by weight: 32 parts of acrylate emulsion, 5 parts of the fluorescent whitening agent prepared in Example 1, 1 part of the modified additive prepared in Example 2, and 10 parts of deionized water.

[0041] The preparation method of the fluorescent whitening composition comprises the following steps: mixing acrylate emulsion, fluorescent whitening agent, modifying additive and deionized water by stirring at a stirring speed of 80 rpm for 40 minutes, and obtaining the fluorescent whitening composition after the stirring is completed.

[0042] Example 4 A fluorescent whitening composition comprises the following components in parts by weight: 40 parts of acrylate emulsion, 8 parts of the fluorescent whitening agent prepared in Example 1, 3 parts of the modified additive prepared in Example 2, and 18 parts of deionized water.

[0043] The preparation method of the fluorescent whitening composition is the same as that of Example 3.

[0044] Example 5 A fluorescent whitening composition comprises the following components in parts by weight: 44 parts of acrylate emulsion, 12 parts of the fluorescent whitening agent prepared in Example 1, 5 parts of the modified additive prepared in Example 2, and 23 parts of deionized water.

[0045] The preparation method of the fluorescent whitening composition is the same as that of Example 3.

[0046] Comparative Example 1: A fluorescent whitening composition comprises the following components in parts by weight: 32 parts of acrylate emulsion, 5 parts of commercially available fluorescent whitening agent VBL, 1 part of the modified additive prepared in Example 2, and 10 parts of deionized water.

[0047] The preparation method of the fluorescent whitening composition is the same as that of Example 3.

[0048] Comparative Example 2: A fluorescent whitening composition comprising the following components in parts by weight: 32 parts of acrylate emulsion, 5 parts of the fluorescent whitening agent prepared in Example 1, and 10 parts of deionized water.

[0049] The preparation method of the fluorescent whitening composition is the same as that of Example 3.

[0050] Performance Testing

[0051] The poplar APMP is cut into sheets with a weight of 100 g / m 2The fluorescent whitening compositions prepared in Examples 3-5 and Comparative Examples 1-2 were coated on the surface of the paper respectively, with a coating amount of 2 g / m 2 , and then perform performance testing:

[0052] (1) Mechanical properties test: The tensile strength and tear strength of the coated paper were tested using a tensile strength tester and a tear strength tester. The data results are shown in Table 1.

[0053] (2) Whiteness and yellowing value test: After the paper sample is air-dried, it is placed in a UV aging box for UV aging test. The output power of the UV aging box is 5.3mW / cm 2 , the temperature was set to 25°C, the wavelength of the UV lamp was 340nm, the paper sample was laid flat in the box, and exposed to light for 38 hours. The whiteness was measured using a colorimeter, and the yellowing value (PC value) was calculated. The data results are shown in Table 1.

[0054] (3) UV aging test: The paper sample was placed in a UV aging box, and the height of the light source was adjusted so that the paper sample was about 10 cm away from the light source. The light source was 254 nm UV light, and the irradiation time was 72 h. The data results are shown in Table 1.

[0055] (4) Dry heat aging test: Referring to GB / T 464-2008, the paper sample was placed in a constant temperature drying oven, the aging temperature was 105°C, and the aging time was 72 h. The data results are shown in Table 1.

[0056] (5) Water resistance test: The contact angle of a water drop on the paper surface for 6 seconds was measured using a contact angle tester. The data results are shown in Table 1.

[0057] Table 1 Test results of sample performance

[0058]

[0059] It can be seen from the data in Table 1 that the fluorescent whitening compositions prepared in Examples 3-5 of the present invention and Comparative Examples 1-2 can impart excellent tensile strength and tear resistance to paper, and can significantly improve the whiteness of paper, and have a significant effect on inhibiting the yellowing of paper. The water contact angle is increased, thereby improving the water resistance and waterproofness of the paper.

[0060] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0061] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A fluorescent whitening composition, characterized in that: The invention comprises the following components by weight: 30 to 45 parts of acrylic emulsion, 5 to 12 parts of fluorescent whitening agent, 1 to 5 parts of modified additive, and 10 to 25 parts of deionized water; The fluorescent brightener is an amination-modified fluorescent matrix grafted with nano-titanium dioxide. The modified fluorescent matrix is ​​prepared by a first step nucleophilic substitution reaction between cyanuric chloride and p-aminobenzenesulfonic acid and a second step nucleophilic substitution reaction with the fluorescent matrix 4,4-diaminostilbene-2,2-disulfonic acid. The structural formula of the modified fluorescent matrix is ​​as follows: The modified additive is prepared by covalently grafting graphene oxide onto the surface of nano silicon dioxide and grafting tert-butyl glycidyl carbonate.

2. The fluorescent whitening composition according to claim 1, characterized in that The preparation method of the fluorescent whitening agent comprises the following steps: A. Take cyanuric chloride and deionized water in a reactor, place them in an ice water bath and stir them evenly, dissolve p-aminobenzenesulfonic acid in deionized water and add them to the reactor, adjust the pH value of the system to 6, control the reaction temperature to 0-5°C, react for 2-3h, and obtain the initial product; B. Dissolve 4,4-diaminostilbene-2,2-disulfonic acid and anhydrous potassium carbonate in deionized water, adjust the pH value of the system to 7-8 to obtain a mixed solution, add the mixed solution to the initial product, continue to adjust the pH value of the system to 7-8, and then place it at 45-60°C for 2-4h to obtain a modified fluorescent matrix; C. Ultrasonic dispersion of nano-titanium dioxide in a mixture of ethanol and deionized water, dropwise addition of glacial acetic acid to adjust the pH value of the system to 4-5, raise the temperature to 70-85°C, slowly dropwise addition of 3-aminopropyltriethoxysilane, react for 6-8h after the addition is completed, centrifuge, wash, and dry to obtain amino-modified nano-titanium dioxide; D. Add amino nano-titanium dioxide to the modified fluorescent matrix, raise the temperature to 80-95°C, adjust the pH value of the system to 9-10, react for 2-4 hours, filter, wash and dry to obtain a fluorescent whitening agent.

3. The fluorescent whitening composition according to claim 2, characterized in that The molar ratio of cyanuric chloride, p-aminobenzenesulfonic acid, 4,4-diaminobenzene-2,2-disulfonic acid, anhydrous potassium carbonate and amino nano titanium dioxide is 1:1.05-1.5:0.5-0.8:0.5-0.8:0.6-1.

4. The fluorescent whitening composition according to claim 1, characterized in that The preparation method of the modified additive comprises the following steps: (1) taking nano-silica and dispersing it in anhydrous ethanol by ultrasonic, adding γ-glycidyloxypropyltrimethoxysilane, passing nitrogen gas under reflux for 2 to 4 hours, cooling to room temperature after the reaction is completed, washing and drying, and preparing modified nano-silica; (2) ultrasonically dispersing graphene oxide in deionized water to obtain a dispersion, dissolving lysine in deionized water, adjusting the pH value of the system to 7-8 to obtain a mixed solution, mixing the dispersion with the mixed solution and ultrasonically dispersing the mixture, reacting at 25-40° C. for 18-24 h, and washing and drying after the reaction to obtain modified graphene oxide; (3) taking modified graphene oxide and modified nano-silica into a reactor, adding deionized water for ultrasonic dispersion, and then reacting at 40 to 50° C. for 16 to 24 hours. After the reaction is completed, washing and drying are performed to prepare a composite additive; (4) The composite additive is dissolved in butyl acetate and ultrasonically dispersed, triphenylphosphine is added, the temperature is raised to 90-120° C., and then tert-butyl glycidyl carbonate is added to react for 8-12 hours. After the reaction is completed, the modified additive is prepared by filtration, washing, and drying.

5. The fluorescent whitening composition according to claim 4, characterized in that: In the step (2), the ratio of graphene oxide to lysine is 1:3-5.

6. The fluorescent whitening composition according to claim 4, characterized in that: In the step (3), the mass ratio of modified graphene oxide to modified nano-silicon dioxide is 2 to 3:

1.

7. The fluorescent whitening composition according to claim 4, characterized in that: In the step (4), the mass ratio of the composite additive to tert-butyl glycidyl carbonate is 1:4-8.

8. The method for preparing the fluorescent whitening composition according to claim 1, characterized in that: The method comprises the following steps: mixing acrylate emulsion, fluorescent whitening agent, modification additive and deionized water by stirring, the stirring speed is 60-120 rpm, the time is 0.5-1h, and the fluorescent whitening composition is obtained after the stirring is completed.

9. Use of the fluorescent whitening composition according to claim 1 in paper, characterized in that: The fluorescent whitening composition is used for coating the surface of paper.

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