A flame retardant coating agent for surface modification of wood and paper and its preparation method

Abstract

The present invention belongs to the technical field of flame-retardant coating agents, and particularly relates to a flame-retardant coating agent for surface modification of wood and paper and a preparation method thereof. The flame-retardant coating agent for surface modification of wood and paper comprises the following components in parts by weight: 70-80 parts of modified epoxy resin, 25-30 parts of hydroxyl-terminated hyperbranched polyester, 10-15 parts of modified material, and 20-30 parts of isocyanate curing agent; the preparation raw materials of the modified epoxy resin are phase A and phase B; wherein phase A is DEM resin, and phase B is a free radical photoinitiator and a polyetheramine-based epoxy thermosetting agent. The flame-retardant coating agent prepared by the present invention has excellent comprehensive performance and is suitable for being used as a surface coating agent for electrostatic copying paper.

Description

Technical Field

[0001] The present invention belongs to the technical field of flame - retardant coating agents, and particularly relates to a flame - retardant coating agent for surface modification of wood and paper and a preparation method thereof. Background Art

[0002] Electrostatic copying paper is a type of paper designed specifically for copiers and laser printers. Its surface is specially treated to improve the quality of copying or printing and reduce the problem of multiple - page paper sticking caused by static electricity. Electrostatic copying paper usually has better smoothness, higher hardness, and a more uniform charge distribution, and these characteristics help to improve the operating efficiency of the equipment and the output quality.

[0003] However, there are also some problems in the use of electrostatic copying paper: (1) For places storing a large number of documents and materials, such as archives, libraries, data centers, etc., using paper with certain flame - retardant properties can reduce the fire risk, slow down the spread of fire, thus providing more escape time and reducing property losses. (2) During the printing or copying process, if the coating adhesion is insufficient, it may lead to a decline in image quality and even affect the operation of the equipment. In addition, during handling and storage, it can also avoid coating loss caused by friction and other reasons. (3) Abrasion resistance refers to the ability of the surface to resist wear. For frequently used documents or frequently - flipped files, abrasion resistance is an important consideration. Improving the abrasion resistance of copying paper can extend the service life of the document, especially in the case of long - term preservation of important information. (4) Copying paper is sometimes folded or curled, especially when bound into a volume. Good folding resistance helps to ensure the integrity of the paper during such operations and prevent breakage or delamination. (5) Many copying papers may be used or stored under different climatic conditions, and they may have problems such as poor folding resistance in an environment with large temperature fluctuations.

[0004] In the prior art, organic flame - retardants are added to the coating agent on the surface of electrostatic copying paper to improve the flame - retardant performance, but toxic gases and corrosive gases will be released during combustion, or there are disadvantages such as poor thermal stability and high volatility. And the adhesion of the coating agent adding inorganic flame - retardants on the surface of electrostatic copying paper is not ideal.

[0005] Therefore, there is an urgent need for a flame - retardant coating agent for surface modification of wood and paper and a preparation method thereof. Summary of the Invention

[0006] The purpose of the present invention is to provide a flame - retardant coating agent for surface modification of wood and paper and a preparation method thereof.

[0007] To achieve the above - mentioned purpose, the present invention provides the following technical solutions:

[0008] A flame retardant coating agent for surface modification of wood and paper, comprising the following components in parts by weight: 70-80 parts of modified epoxy resin, 25-30 parts of hydroxyl-terminated hyperbranched polyester, 10-15 parts of modified material, and 20-30 parts of isocyanate curing agent;

[0009] The raw materials for preparing the modified epoxy resin are phase A and phase B; wherein phase A is DEM resin, and phase B is a free radical photoinitiator and a polyetheramine-based epoxy thermosetting agent;

[0010] The raw materials for preparing the DEM resin are: DGEBA resin, methacrylic acid, glycidyl methacrylate, p-hydroxyanisole, benzyltriethylammonium chloride; the molar ratio of the DGEBA resin to methacrylic acid is (1.8-2.2):1; the amount of glycidyl methacrylate is 75-79% of the mass of the DGEBA resin; the amount of p-hydroxyanisole is 0.2-0.4% of the mass of the DGEBA resin; the amount of benzyltriethylammonium chloride is 0.1-0.2% of the mass of the DGEBA resin.

[0011] Furthermore, the preparation method of the DEM resin includes: in a four-necked flask, first add DGEBA resin and p-hydroxyanisole, then introduce nitrogen and heat up to 60-65°C, pour methacrylic acid into a constant pressure funnel, and drop it into the four-necked flask while slowly heating up to 115-120°C. Add benzyltriethylammonium chloride and react for 2-3 h. During this period, measure the acid value of the system every 30-40 min until the acid value of the system drops below 3 mgKOH / g, and the reaction terminates; cool down to 40-45°C, add glycidyl methacrylate, stir well for 5-10 min and then discharge to obtain it.

[0012] Furthermore, the free radical photoinitiator is 184 initiator and TPO; the mass ratio of the 184 initiator to the DEM resin is (0.5-0.7):100; the mass ratio of TPO to the DEM resin is (0.5-0.7):100.

[0013] In the present invention, by modifying DGEBA, the adhesion of the flame retardant coating agent on the surface of electrostatic copying paper can be improved. The epoxy group in DGEBA (bisphenol A type epoxy resin, E51) undergoes a ring-opening addition reaction with the carboxyl group in methacrylic acid, and the epoxy group in glycidyl methacrylate continues to undergo a ring-opening addition reaction with the remaining carboxyl group in the system to generate more ester bonds. The 184 initiator and TPO are used as photoinitiators, which generate free radicals under light irradiation, and initiate the polymerization reaction of the unsaturated bonds in the system to form a three-dimensional network structure. By increasing polar functional groups and introducing methacrylic acid and glycidyl methacrylate, the polar functional groups in the resin are increased, and these polar groups can form hydrogen bonds or van der Waals forces with the hydroxyl groups or other polar groups on the paper surface, thereby enhancing the adhesion.

[0014] Furthermore, the polyetheramine epoxy thermosetting agent has a grade of D230, and the mass ratio of the polyetheramine epoxy thermosetting agent of grade D230 to the DEM resin is (20 - 25):100.

[0015] Furthermore, the hydroxyl-terminated hyperbranched polyester includes hydroxyl-terminated hyperbranched polyester A, hydroxyl-terminated hyperbranched polyester B, and hydroxyl-terminated hyperbranched polyester C with a weight ratio of 1:(1.2 - 1.4):(0.4 - 0.6); the hydroxyl number of hydroxyl-terminated hyperbranched polyester A is 10 - 12 / mol, the hydroxyl value is 600 mgKOH / g, and the molecular weight is 1100 g / mol; the hydroxyl number of hydroxyl-terminated hyperbranched polyester B is 20 - 24 / mol, the hydroxyl value is 500 mgKOH / g, and the molecular weight is 2600 g / mol; the hydroxyl number of hydroxyl-terminated hyperbranched polyester C is 10 - 12 / mol, the hydroxyl value is 260 mgKOH / g, and the molecular weight is 2500 g / mol.

[0016] By adding hydroxyl-terminated hyperbranched polyester to the coating agent in the present invention, the flexural resistance performance of the coating agent on the surface of electrostatic copying paper can be improved. The hydroxyl groups in the hydroxyl-terminated hyperbranched polyester can undergo cross-linking reactions with other functional components such as modified epoxy resins to form a denser and more stable three-dimensional network structure. This network structure with a high cross-linking density can effectively resist external stresses and improve the overall strength and durability of the coating.

[0017] Furthermore, the preparation method of the modified material includes the following steps:

[0018] (1) Mix cerium dioxide, titanium dioxide, and carbon nanotubes with a weight ratio of 1:(0.5 - 0.7):(1.2 - 1.4) to obtain a mixed material;

[0019] (2) Mix silane coupling agent KH570, ethanol, and water with a molar ratio of 1:(4 - 6):(3 - 5), and hydrolyze at 30 - 35 °C for 40 - 50 min to obtain a hydrolyzate;

[0020] (3) Mix the mixed material and the hydrolyzate with a weight ratio of 10:(13 - 15), heat up to 100 - 110 °C, stir and react for 60 - 70 min, continue to heat up to 125 - 130 °C, add 1 part by weight of triglycidyl isocyanurate, react for 60 - 80 min, and dry to obtain the modified material.

[0021] Furthermore, the particle size of the cerium dioxide is 30 - 50 nm, and the specific surface area is 20 - 40 m 2 / g; the particle size of the titanium dioxide is 10 nm, and the specific surface area is 30 - 50 m 2 / g; the inner diameter of the carbon nanotube is 10 - 20 nm, the tube length is 5 - 15 μm, and the specific surface area is 120 - 180 m2 / g.

[0022] By modifying cerium dioxide, titanium dioxide, and carbon nanotubes with flame retardant effects, the present invention improves their compatibility and dispersibility in the system, and can improve the flame retardant performance of the flame retardant coating agent. , CeO₂, TiO₂, and CNTs each have different flame retardant mechanisms. Through reasonable proportioning and surface modification treatment, the synergistic effect of multiple flame retardant mechanisms can be achieved. By performing surface modification treatment on cerium dioxide, titanium dioxide, and carbon nanotubes with flame retardant effects, the present invention significantly improves the compatibility and dispersibility of these nanomaterials in the flame retardant coating agent. This improvement not only enhances the synergistic effect between components, but also significantly improves the overall flame retardant performance of the coating agent through the combined action of multiple flame retardant mechanisms. At the same time, the application of silane coupling agent KH570 and triglycidyl isocyanurate further enhances the crosslinking density and mechanical strength of the coating, and simultaneously improves the wear resistance of the coating agent.

[0023] Moreover, when the present invention simultaneously uses three kinds of hydroxyl-terminated hyperbranched polyesters with specific parameters and cerium dioxide, titanium dioxide, and carbon nanotubes with specific parameters, the flexural resistance performance of the coating agent on the surface of electrostatic copying paper under variable temperature conditions can be improved.

[0024] The present invention also provides a preparation method of a flame retardant coating agent for surface modification of wood and paper, which includes the following steps:

[0025] (1) The preparation method of the modified epoxy resin is as follows: under light-shielded conditions, mix the raw materials of phase B and add them to phase A, stir and mix evenly to obtain the modified epoxy resin;

[0026] (2) Mix the modified epoxy resin and other components evenly to obtain a flame retardant coating agent for surface modification of wood and paper.

[0027] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0028] 1. By modifying DGEBA, the present invention can improve the adhesion of the flame retardant coating agent on the surface of electrostatic copying paper.

[0029] 2. By adding hydroxyl-terminated hyperbranched polyester to the coating agent, the present invention can improve the flexural resistance performance of the coating agent on the surface of electrostatic copying paper.

[0030] 3. By modifying cerium dioxide, titanium dioxide, and carbon nanotubes with flame retardant effects, the present invention improves their compatibility and dispersibility in the system, and can improve the flame retardant performance of the flame retardant coating agent. At the same time, the wear resistance of the coating agent is improved.

[0031] 4. When using a hydroxyl-terminated hyperbranched polyester with three specific parameters and a compound of cerium dioxide, titanium dioxide, and carbon nanotubes with specific parameters, the flexural resistance performance of the coating agent on the surface of electrostatic copying paper under variable temperature conditions can be improved. Detailed implementation manners

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0033] All raw materials used in the following embodiments of the present invention are commercially available products:

[0034] The DGEBA resin is an E51 type epoxy resin. It is purchased from Jinan Qingtian Chemical Technology Co., Ltd.

[0035] The isocyanate curing agent, brand Evonik, model VESTAGON B1530.

[0036] The 184 initiator, CAS number 947-19-3.

[0037] TPO, CAS number 1456769-77-9.

[0038] The grade of the polyetheramine epoxy thermosetting agent is D230, brand: Huntsman. Example 1

[0039] This example provides a flame-retardant coating agent for the surface modification of wood and paper, comprising the following components in parts by weight: 75 parts of modified epoxy resin, 27 parts of hydroxyl-terminated hyperbranched polyester, 13 parts of modified material, and 25 parts of isocyanate curing agent;

[0040] The preparation raw materials of the modified epoxy resin are phase A and phase B; wherein phase A is DEM resin, and phase B is a free radical photoinitiator and a polyetheramine epoxy thermosetting agent;

[0041] The preparation raw materials of the DEM resin are: DGEBA resin, methacrylic acid, glycidyl methacrylate, p-methoxyphenol, and benzyltriethylammonium chloride; the molar ratio of the DGEBA resin to methacrylic acid is 2:1; the dosage of glycidyl methacrylate is 76% of the mass of the DGEBA resin; the dosage of p-methoxyphenol is 0.3% of the mass of the DGEBA resin; the dosage of benzyltriethylammonium chloride is 0.15% of the mass of the DGEBA resin.

[0042] The preparation method of the DEM resin includes: in a four-necked flask, first add DGEBA resin and p-methoxyphenol, then introduce nitrogen and heat up to 62 °C. Pour methacrylic acid into a constant pressure funnel and drop it into the four-necked flask, while slowly heating up to 117 °C. Add benzyltriethylammonium chloride and react for 2.5 h. During this period, measure the acid value of the system every 35 min until the acid value of the system drops below 3 mg KOH / g, and then terminate the reaction. Cool down to 42 °C, add glycidyl methacrylate, stir well for 7 min and then discharge to obtain the product.

[0043] The radical photoinitiator is 184 initiator and TPO; the mass ratio of 184 initiator to DEM resin is 0.6:100; the mass ratio of TPO to DEM resin is 0.6:100.

[0044] The polyetheramine epoxy thermosetting curing agent has the brand number D230, and the mass ratio of the polyetheramine epoxy thermosetting curing agent with the brand number D230 to DEM resin is 23:100.

[0045] The hydroxyl-terminated hyperbranched polyester includes hydroxyl-terminated hyperbranched polyester A, hydroxyl-terminated hyperbranched polyester B and hydroxyl-terminated hyperbranched polyester C with a weight ratio of 1:1.3:0.5; the hydroxyl number of hydroxyl-terminated hyperbranched polyester A is 10 - 12 / mol, hydroxyl value is 600 mg KOH / g, molecular weight is 1100 g / mol, and the model is H102; the hydroxyl number of hydroxyl-terminated hyperbranched polyester B is 20 - 24 / mol, hydroxyl value is 500 mg KOH / g, molecular weight is 2600 g / mol, and the model is H203; the hydroxyl number of hydroxyl-terminated hyperbranched polyester C is 10 - 12 / mol, hydroxyl value is 260 mg KOH / g, molecular weight is 2500 g / mol, and the model is H302. It is purchased from Wuhan Hyperbranched Resin Technology Co., Ltd.

[0046] The preparation method of the modified material includes the following steps:

[0047] (1) Mix cerium dioxide, titanium dioxide and carbon nanotubes with a weight ratio of 1:0.6:1.3 to obtain a mixed material;

[0048] (2) Mix silane coupling agent KH570, ethanol and water with a molar ratio of 1:5:4, and hydrolyze at 32 °C for 45 min to obtain a hydrolysis solution;

[0049] (3) Mix the mixed material and the hydrolysis solution with a weight ratio of 10:13, heat up to 105 °C, stir and react for 65 min, continue to heat up to 128 °C, add 1 part by weight of triglycidyl isocyanurate, react for 70 min, and dry to obtain the modified material.

[0050] The particle size of the cerium dioxide is 30 - 50 nm, and the specific surface area is 20 - 40 m 2 / g, model ZT-Ce03, Zhejiang Zhitainawei New Materials Co., Ltd.; the particle size of the titanium dioxide is 10 nm, and the specific surface area is 30 - 50 m 2 / g, model DK-TiO2-A10, Beijing Decodaojin Technology Co., Ltd.; the inner diameter of the carbon nanotube is 10 - 20 nm, the tube length is 5 - 15 μm, and the specific surface area is 120 - 180 m 2 / g. Purchased from Shanghai Maoguo Nano Technology Co., Ltd.

[0051] The preparation method of the flame retardant coating agent for wood and paper surface modification includes the following steps:

[0052] (1) The preparation method of the modified epoxy resin is as follows: under light-shielded conditions, mix the raw materials of phase B and add them to phase A, stir and mix evenly to obtain the modified epoxy resin;

[0053] (2) Mix the modified epoxy resin and other components evenly to obtain the flame retardant coating agent for wood and paper surface modification. Example 2

[0054] This example provides a flame retardant coating agent for wood and paper surface modification, including the following components in parts by weight: 70 parts of modified epoxy resin, 30 parts of hydroxyl-terminated hyperbranched polyester, 10 parts of modified material, and 30 parts of isocyanate curing agent;

[0055] The preparation raw materials of the modified epoxy resin are phase A and phase B; among them, phase A is DEM resin, and phase B is free radical photoinitiator and polyetheramine-based epoxy thermosetting agent;

[0056] The preparation raw materials of the DEM resin are: DGEBA resin, methacrylic acid, glycidyl methacrylate, p-hydroxyanisole, benzyltriethylammonium chloride; the molar ratio of the DGEBA resin to methacrylic acid is 1.8:1; the dosage of glycidyl methacrylate is 79% of the mass of the DGEBA resin; the dosage of p-hydroxyanisole is 0.2% of the mass of the DGEBA resin; the dosage of benzyltriethylammonium chloride is 0.2% of the mass of the DGEBA resin.

[0057] The preparation method of the DEM resin includes: in a four-necked flask, first add DGEBA resin and p-hydroxyanisole, then introduce nitrogen and heat up to 65 °C, pour methacrylic acid into a constant pressure funnel, drop it into the four-necked flask, and at the same time slowly heat up to 120 °C, add benzyltriethylammonium chloride and react for 2 h. During this period, measure the acid value of the system every 40 min until the acid value of the system drops below 3 mgKOH / g, and the reaction terminates; cool down to 40 °C, add glycidyl methacrylate, stir well for 10 min and then discharge to obtain it.

[0058] The radical photoinitiators are initiator 184 and TPO; the mass ratio of initiator 184 to DEM resin is 0.7:100; the mass ratio of TPO to DEM resin is 0.7:100.

[0059] The polyetheramine epoxy thermosetting agent has the brand number D230, and the mass ratio of the polyetheramine epoxy thermosetting agent with the brand number D230 to DEM resin is 21:100.

[0060] The hydroxyl-terminated hyperbranched polyester includes hydroxyl-terminated hyperbranched polyester A, hydroxyl-terminated hyperbranched polyester B, and hydroxyl-terminated hyperbranched polyester C with a weight ratio of 1:1.2:0.4; the hydroxyl number of hydroxyl-terminated hyperbranched polyester A is 10 - 12 / mol, the hydroxyl value is 600 mgKOH / g, the molecular weight is 1100 g / mol, and the model is H102; the hydroxyl number of hydroxyl-terminated hyperbranched polyester B is 20 - 24 / mol, the hydroxyl value is 500 mgKOH / g, the molecular weight is 2600 g / mol, and the model is H203; the hydroxyl number of hydroxyl-terminated hyperbranched polyester C is 10 - 12 / mol, the hydroxyl value is 260 mgKOH / g, the molecular weight is 2500 g / mol, and the model is H302. It is purchased from Wuhan Hyperbranched Resin Technology Co., Ltd.

[0061] The preparation method of the modified material includes the following steps:

[0062] (1) Mix cerium dioxide, titanium dioxide, and carbon nanotubes with a weight ratio of 1:0.5:1.2 to obtain a mixed material;

[0063] (2) Mix silane coupling agent KH570, ethanol, and water with a molar ratio of 1:4:5, and hydrolyze at 30 °C for 50 min to obtain a hydrolysis solution;

[0064] (3) Mix the mixed material and the hydrolysis solution with a weight ratio of 2:3, heat up to 110 °C, stir and react for 60 min, continue to heat up to 130 °C, add 1 part by weight of triglycidyl isocyanurate, react for 80 min, and dry to obtain the modified material.

[0065] The particle size of the cerium dioxide is 30 - 50 nm, the specific surface area is 20 - 40 m 2 / g, the model is ZT-Ce03, Zhejiang Zhitaina Micro New Materials Co., Ltd.; the particle size of the titanium dioxide is 10 nm, the specific surface area is 30 - 50 m 2 / g, the model is DK-TiO2-A10, Beijing Decodaojin Technology Co., Ltd.; the inner diameter of the carbon nanotubes is 10 - 20 nm, the tube length is 5 - 15 μm, and the specific surface area is 120 - 180 m 2 / g. It is purchased from Shanghai Maoguo Nano Technology Co., Ltd.

[0066] The preparation method of the flame retardant coating agent for surface modification of wood and paper comprises the following steps:

[0067] (1) The preparation method of the modified epoxy resin is as follows: under light-shielded conditions, mix the raw materials in phase B and add them to phase A, then stir and mix evenly to obtain the modified epoxy resin;

[0068] (2) Mix the modified epoxy resin and other components evenly to obtain the flame retardant coating agent for surface modification of wood and paper.

[0069] Comparative Example 1

[0070] The difference between this comparative example and Example 1 is that the modified epoxy resin is replaced by DGEBA resin. The DGEBA resin is type E51 epoxy resin. It is purchased from Jinan Qingtian Chemical Technology Co., Ltd.

[0071] Comparative Example 2

[0072] The difference between this comparative example and Example 1 is that the hydroxyl-terminated hyperbranched polyester comprises hydroxyl-terminated hyperbranched polyester A, hydroxyl-terminated hyperbranched polyester B and hydroxyl-terminated hyperbranched polyester C with a weight ratio of 1:1:1; the hydroxyl number of hydroxyl-terminated hyperbranched polyester A is 10 - 12 / mol, hydroxyl value is 600mgKOH / g, and molecular weight is 1100g / mol; the hydroxyl number of hydroxyl-terminated hyperbranched polyester B is 20 - 24 / mol, hydroxyl value is 500mgKOH / g, and molecular weight is 2600g / mol; the hydroxyl number of hydroxyl-terminated hyperbranched polyester C is 10 - 12 / mol, hydroxyl value is 260mgKOH / g, and molecular weight is 2500g / mol.

[0073] Comparative Example 3

[0074] The difference between this comparative example and Example 1 is that the hydroxyl-terminated hyperbranched polyester comprises hydroxyl-terminated hyperbranched polyester A, hydroxyl-terminated hyperbranched polyester B and hydroxyl-terminated hyperbranched polyester C with a weight ratio of 1:1.3:0.5; the hydroxyl number of hydroxyl-terminated hyperbranched polyester A is 5 - 7 / mol, hydroxyl value is 670mgKOH / g, and molecular weight is 500g / mol, model H101; the hydroxyl number of hydroxyl-terminated hyperbranched polyester B is 20 - 24 / mol, hydroxyl value is 240mgKOH / g, and molecular weight is 5500g / mol, model H303; the hydroxyl number of hydroxyl-terminated hyperbranched polyester C is 40 - 45 / mol, hydroxyl value is 230mgKOH / g, and molecular weight is 11500g / mol, model H304. It is purchased from Wuhan Hyperbranched Resin Technology Co., Ltd.

[0075] Comparative Example 4

[0076] The difference between this comparative example and Example 1 is that only one type of hydroxyl-terminated hyperbranched polyester is used, with a hydroxyl number of 20 - 24 / mol, a hydroxyl value of 500 mg KOH / g, a molecular weight of 2600 g / mol, and the type is H203. It is purchased from Wuhan Hyperbranched Resin Technology Co., Ltd.

[0077] Comparative Example 5

[0078] The difference between this comparative example and Example 1 is that cerium dioxide, titanium dioxide, and carbon nanotubes are mixed in a weight ratio of 1:1:1 to obtain a mixture.

[0079] Comparative Example 6

[0080] The difference between this comparative example and Example 1 is that the cerium dioxide has a particle size of 0.2 - 0.3 μm and a specific surface area of 10 - 20 m 2 / g, with the type ZT-Ce02, from Zhejiang Zhitaina Micro New Materials Co., Ltd.; the titanium dioxide has a particle size of 60 nm and a specific surface area of 20 - 30 m 2 / g, with the type DK-TiO2-A60, from Beijing Decod Island Gold Technology Co., Ltd.; the carbon nanotubes have an inner diameter of 15 - 30 nm, a tube length of 10 - 30 μm, and a specific surface area of 50 - 80 m 2 / g. Purchased from Xianfeng Nano.

[0081] Performance Testing

[0082] The electrostatic copying paper used for testing (《Electrostatic Copying Paper》(GB / T 22339 - 2008), with a basis weight of 70.0 g / m 2 , a tensile strength of 18.65 MPa, and an elongation at break of 8.9%), is used as the substrate to prepare samples of the same size, 70×210 mm. The dropping amount of the coating agent is 0.18 mL / cm 2 , and it is sprayed using a spray gun. After standing to make the coating uniform, it is stored at room temperature of 25℃ for 12 h to obtain the test paper samples.

[0083] (1) The samples are subjected to a horizontal flame test using a methane flame (around 500℃) to evaluate the total combustion time of the samples. According to the flame retardancy performance detected by national standards, the afterflame time is measured. In the national standards for flame retardant paper, it is stipulated that the average afterflame time ≤ 5 s.

[0084] (2) Refer to GBT 9286 - 2021 to determine the adhesion.

[0085] (3) Refer to GB / T 1768 - 2006 《Determination of abrasion resistance of paints and varnishes: Rotating rubber wheel method》 to determine the abrasion resistance of the coating.

[0086] (4)Flexure resistance test: Test the test paper samples on a flexure resistance testing machine. Set the number of flexure tests for the test paper samples to 10,000 times. Observe whether there are obvious cracks in the test paper samples and whether there is delamination at the crease. If there are no obvious cracks and no delamination at the crease, it is recorded as qualified; otherwise, it is recorded as unqualified.

[0087] (5)Flexure resistance test at variable temperatures: Place the test paper samples at -10°C, 25°C, and 50°C for 10 days in sequence as one cycle, and test a total of 3 cycles. Then conduct a flexure resistance test at room temperature. Observe whether there are obvious cracks in the test paper samples and whether there is delamination at the crease. If there are no obvious cracks and no delamination at the crease, it is recorded as qualified; otherwise, it is recorded as unqualified.

[0088] Table 1 Performance test results

[0089] Afterglow time s Adhesion Wear resistance mg / 1000r Flexing resistance test Flexing resistance test at varying temperatures Example 1 4.2 Grade 1 6.6 Qualified Qualified Example 2 4.6 Grade 1 6.8 Qualified Qualified Comparative example 1 4.4 Grade 2 7.3 Unqualified Unqualified Comparative example 2 4.3 Grade 1 7.0 Unqualified Unqualified Comparative example 3 4.4 Grade 1 6.9 Unqualified Unqualified Comparative example 4 4.5 Grade 2 7.1 Unqualified Unqualified Comparative example 5 6.2 Grade 2 7.9 Qualified Unqualified Comparative example 6 5.7 Grade 2 7.5 Qualified Unqualified

[0090] From the above performance test results, it can be seen that the flame-retardant coating agents of Examples 1-2 have good coating effects on the surface of electrostatic copying paper. In particular, the comprehensive performance of Example 1 is the most prominent, which is mainly due to the synergistic compounding of components.

[0091] For the comparative examples, because the necessary technical solutions were not adopted, their performance in the corresponding performance tests is significantly worse than that of the examples. In Comparative Example 1, DGEBA was not modified, resulting in a decrease in the adhesion of the flame-retardant coating agent on the surface of electrostatic copying paper. In Comparative Example 2, the ratio of the hydroxyl-terminated hyperbranched polyester was different. In Comparative Example 3, the parameters of the three hydroxyl-terminated hyperbranched polyesters were different. In Comparative Example 4, only one hydroxyl-terminated hyperbranched polyester was used, resulting in a decrease in the flexure resistance performance of the coating agent on the surface of electrostatic copying paper. And it can be found that when using hydroxyl-terminated hyperbranched polyesters with different parameters, the flexure resistance performance at variable temperatures decreases. In Comparative Example 5, the ratio of cerium dioxide, titanium dioxide, and carbon nanotubes, and in Comparative Example 6, the parameters of cerium dioxide, titanium dioxide, and carbon nanotubes are different, resulting in a decrease in the flame retardancy and wear resistance of the flame-retardant coating agent. And when the parameters of cerium dioxide, titanium dioxide, and carbon nanotubes are different, the flexure resistance performance at variable temperatures decreases. The above experimental results further prove the importance of the technical solutions defined in the present invention for its technical effects.

[0092] The above is the preferred implementation manner of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle described in the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A multifunctional flame retardant coating agent for surface modification of wood and paper, characterized in that, It comprises the following components in parts by weight: 70 - 80 parts of modified epoxy resin, 25 - 30 parts of hydroxyl-terminated hyperbranched polyester, 10 - 15 parts of modified material, and 20 - 30 parts of isocyanate curing agent; The raw materials for preparing the modified epoxy resin are phase A and phase B; phase A is DEM resin, and phase B is a free radical photoinitiator and a polyetheramine-based epoxy thermal curing agent; The raw materials for preparing DEM resin are: DGEBA resin, methacrylic acid, glycidyl methacrylate, p-methoxyphenol, benzyltriethylammonium chloride; The molar ratio of DGEBA resin to methacrylic acid is (1.8 - 2.2):1; the dosage of p-methoxyphenol is 0.2 - 0.4% of the mass of DGEBA resin; the dosage of benzyltriethylammonium chloride is 0.1 - 0.2% of the mass of DGEBA resin; The preparation method of DEM resin: In a four-necked flask, first add DGEBA resin and p-methoxyphenol, then introduce nitrogen and heat up to 60 - 65 °C. Pour methacrylic acid into a constant pressure funnel and drip it into the four-necked flask, while slowly heating up to 115 - 120 °C. Add benzyltriethylammonium chloride and react for 2 - 3 h. Measure the acid value of the system every 30 - 40 min during this period until the acid value of the system drops below 3 mgKOH / g, and the reaction terminates; cool down to 40 - 45 °C, add 75 - 79% of the mass of DGEBA resin of glycidyl methacrylate, stir well for 5 - 10 min and then discharge to obtain it; The hydroxyl-terminated hyperbranched polyester comprises hydroxyl-terminated hyperbranched polyester A with a hydroxyl number of 10 - 12 / mol, a hydroxyl value of 600 mgKOH / g, and a molecular weight of 1100 g / mol, hydroxyl-terminated hyperbranched polyester B with a hydroxyl number of 20 - 24 / mol, a hydroxyl value of 500 mgKOH / g, and a molecular weight of 2600 g / mol, and hydroxyl-terminated hyperbranched polyester C with a hydroxyl number of 10 - 12 / mol, a hydroxyl value of 260 mgKOH / g, and a molecular weight of 2500 g / mol in a weight ratio of 1:(1.2 - 1.4):(0.4 - 0.6); The preparation method of the modified material includes: (1) Mix cerium dioxide with a particle size of 30 - 50 nm and a specific surface area of 20 - 40 m 2 / g, titanium dioxide with a particle size of 10 nm and a specific surface area of 30 - 50 m 2 / g, and carbon nanotubes with an inner diameter of 10 - 20 nm, a tube length of 5 - 15 μm, and a specific surface area of 120 - 180 m 2 / g in a weight ratio of 1:(0.5 - 0.7):(1.2 - 1.4) to obtain a mixture; (2) Mix silane coupling agent KH570, ethanol, and water in a molar ratio of 1:(4 - 6):(3 - 5), and hydrolyze at 30 - 35 °C for 40 - 50 min to obtain a hydrolysis solution; (3) Mix the mixture and the hydrolysis solution in a weight ratio of 10:(13 - 15), heat up to 100 - 110 °C, stir and react for 60 - 70 min, continue to heat up to 125 - 130 °C, add 1 part by weight of triglycidyl isocyanurate, react for 60 - 80 min, and dry to obtain it.

2. The multifunctional flame retardant coating agent for wood and paper surface modification according to claim 1, characterized in that, The free radical photoinitiator is initiator 184 and TPO.

3. The multifunctional flame retardant coating agent for surface modification of wood and paper according to claim 2, characterized in that, The mass ratio of initiator 184 to DEM resin is (0.5 - 0.7):

100.

4. The multifunctional flame retardant coating agent for wood and paper surface modification according to claim 3, characterized in that, The mass ratio of TPO to DEM resin is (0.5 - 0.7):

100.

5. A method for preparing a multifunctional flame retardant coating agent for surface modification of wood and paper according to any one of claims 1-4, characterized in that, It includes the following steps: (1) The preparation method of the modified epoxy resin is: Under light-shielded conditions, mix the raw materials of phase B, add them to phase A, and stir and mix evenly to obtain the modified epoxy resin; (2) Mix the modified epoxy resin and other components evenly to obtain a multifunctional flame retardant coating agent for surface modification of wood and paper.