Flame-retardant decorative paper and preparation method thereof

Abstract

The invention discloses flame-retardant decorative paper and a preparation method thereof, and relates to the technical field of preparation of decorative materials. The preparation method comprises the following steps: reacting (4-fluorophenyl)-phosphoric acid with dipentaerythritol, introducing phosphorus and fluorine to a molecular chain of the dipentaerythritol, carrying out ring opening with epoxy fluoropropane to obtain branched polyol containing phosphorus and fluorine, reacting the branched polyol containing phosphorus with phenyl thiochloroformate to generate thiocarbonate bonds, reacting with primary amino groups of 1, 2-propane diamine, and carrying out condensation reaction on the primary amino groups of the 1, 2-propane diamine to obtain the high-temperature-resistant flame-retardant flame-retardant flame-retardant flame-retardant flame-retardant flame-retardant flame-retardant flame-retardant flame-retardant flame-retardant. The preparation method comprises the following steps: preparing phosphorus-containing polyhydric alcohol, preparing amino-terminated branched polyether containing phosphorus and sulfur, reacting amino with aldehyde group of 3-fluoropyridine-2-aldehyde to generate an imine bond, adding DOPO to obtain a DOPO derivative containing phosphorus, nitrogen, sulfur and fluorine, reacting branched phosphorus-containing polyhydric alcohol, the DOPO derivative and isocyanate to obtain a polyurethane glue solution containing phosphorus, nitrogen, sulfur and fluorine, and preparing the polyurethane glue solution containing phosphorus, nitrogen, sulfur and fluorine from the polyurethane glue solution containing phosphorus, nitrogen, sulfur and fluorine. And the flame retardance and hydrophobicity of the decorative paper are comprehensively improved by utilizing the synergistic effect of phosphorus, nitrogen, sulfur and fluorine.

Description

Technical Field

[0001] This invention relates to the field of decorative material preparation technology, specifically a flame-retardant decorative paper and its preparation method. Background Technology

[0002] Decorative paper is an indispensable material in many building materials, serving both decorative and anti-seepage purposes. It is primarily made from plant fibers, processed through printing or embossing, and then impregnated with resin. However, it suffers from poor flame retardancy and releases toxic gases when burned.

[0003] With increasing emphasis on environmental protection and higher requirements for decorative paper, the need to develop a decorative paper that is both environmentally friendly and flame-retardant is becoming increasingly urgent. In existing technologies, halogen-free flame retardants are added during the preparation of decorative paper to improve flame retardancy; however, the problem remains that simply adding a single halogen-free flame retardant does not provide sufficient overall flame retardant effect for the decorative paper.

[0004] Therefore, we propose a flame-retardant decorative paper and its preparation method. By coating the surface of the decorative paper with polyurethane adhesive and then drying it, the resulting decorative paper can have a good flame-retardant effect. Summary of the Invention

[0005] The purpose of this invention is to provide a flame-retardant decorative paper and its preparation method to solve the problems raised in the prior art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing flame-retardant decorative paper, comprising the following steps: Take decorative base paper, coat the upper and lower surfaces of the decorative base paper with polyurethane adhesive, dry it to form a flame retardant layer, and obtain flame retardant decorative paper.

[0007] Furthermore, the coating amount of the polyurethane adhesive is 15~25 g / m². 2 ; The flame-retardant layer has a thickness of 6~10μm.

[0008] Furthermore, the drying process conditions are: temperature 90~100℃, time 5~10min.

[0009] Furthermore, the preparation process of the polyurethane adhesive is as follows: Isocyanate, branched phosphorus-containing polyol, 1,4-butanediol, DOPO derivative, and N,N-dimethylcyclohexylamine are mixed and heated to react. The mixture is then cooled to 40-50°C, and triethylamine and azobisisobutyronitrile are added. The mixture is kept at this temperature and then deionized water and anhydrous ethanol are added. The mixture is stirred until homogeneous to obtain a polyurethane adhesive.

[0010] Furthermore, the mass ratio of isocyanate, branched phosphorus-containing polyol, 1,4-butanediol, DOPO derivative, N,N-dimethylcyclohexylamine, triethylamine, azobisisobutyronitrile, deionized water, and anhydrous ethanol is 10:(25~30):(0.5~1.5):(2~6):(0.05~0.15):(0.5~1.5):(0.15~1.0):(25~30):(5~10).

[0011] Furthermore, the process conditions for the heating reaction are: temperature 75~85℃, time 1~2h; The process conditions for the heat preservation reaction are: temperature 40~50℃, time 1~2h.

[0012] Furthermore, the branched phosphorus-containing polyol is prepared by the following process: Dipentaerythritol, (4-fluorophenyl)-phosphoric acid, and N,N-dimethylformamide were mixed and heated to react. Then, glycerol and potassium hydroxide were added and heated to react. After the reaction was completed, under a nitrogen atmosphere, the temperature was raised to 90-100°C, and epifluoropropane was added and mixed. The temperature was raised again to react to obtain branched phosphorus-containing polyol.

[0013] Furthermore, the mass ratio of dipentaerythritol, (4-fluorophenyl)-phosphoric acid, N,N-dimethylformamide, glycerol, potassium hydroxide, and epifluoropropane is (1.5~3.5):1:(6~10):(0.5~1.5):(0.05~0.09):(3.5~4.5).

[0014] Furthermore, the process conditions for the heating reaction are: temperature 60~80℃, time 2~3h; The process conditions for the heating reaction are: temperature 110~120℃, time 1~2h, and pressure 0.06~0.10MPa.

[0015] Furthermore, the DOPO derivative is prepared by the following process: S1: Branched phosphorus-containing polyol, phenyl thiochloroformate, and tetramethylethylenediamine are mixed and reacted under nitrogen atmosphere. After the reaction is completed, 1,2-propanediamine is added and reacted at 20-30℃ for 1-2 hours under vacuum of 50 Pa. The mixture is then distilled to obtain amino-terminated sulfur-containing polyether. S2: Mix amino-terminated sulfur-containing polyether, N,N-dimethylformamide, and 3-fluoropyridine-2-aldehyde, heat and react, then add DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide), and continue the reaction for 10-12 hours to obtain the DOPO derivative.

[0016] Furthermore, in S1, the mass ratio of branched phosphorus-containing polyol, phenyl thiochloroformate, tetramethylethylenediamine, and 1,2-propanediamine is 1:(0.35~0.55):(0.22~0.32):(0.5~0.7).

[0017] Furthermore, in S1, the process conditions for the heating reaction are: temperature 130~140℃, time 3~5h.

[0018] Furthermore, in S2, the ratio of terminal amino-containing sulfur polyether, N,N-dimethylformamide, 3-fluoropyridine-2-aldehyde, and DOPO is 1g:(10~15)mL:(0.9~1.1)g:(1.9~2.1)g.

[0019] Furthermore, in S2, the process conditions for the heating reaction are: temperature 80~90℃, time 8~10h.

[0020] Compared with the prior art, the beneficial effects of the present invention are: 1. In this application, the phosphoric acid group in (4-fluorophenyl)-phosphoric acid is first reacted with the hydroxyl group of dipentaerythritol to introduce phosphorus and fluorine into the molecular chain of dipentaerythritol. Then, it undergoes a ring-opening reaction with epifluoropropane to obtain a branched polyol containing phosphorus and fluorine, which is referred to as a branched phosphorus-containing polyol. Compared to ordinary polyols, the branched structure of branched phosphorus-containing polyols results in greater steric hindrance and more compact molecular chains. Polyurethane adhesives prepared with isocyanates can penetrate deep into the fiber gaps of decorative paper. The branched structure provides multiple hydroxyl sites, which make it easier to interact with polar groups on the substrate surface and improve adhesion.

[0021] 2. In this application, the hydroxyl group of the prepared branched phosphorus-containing polyol reacts with the chlorine group of phenyl thiocarbamate to generate a thiocarbonate bond, and then reacts with the primary amino group of 1,2-propanediamine to obtain a phosphorus- and sulfur-containing terminal amino branched polyether, referred to as terminal amino sulfur-containing polyether; the amino group of the terminal amino sulfur-containing polyether reacts with the aldehyde group of 3-fluoropyridine-2-aldehyde, and then DOPO is added to obtain a DOPO derivative containing phosphorus, nitrogen, sulfur and fluorine. Although the polyurethane adhesive prepared from branched phosphorus-containing polyols and isocyanates contains phosphorus, the flame retardant properties of a single element are limited. Therefore, nitrogen and sulfur are introduced into DOPO to improve the flame retardancy of decorative paper through the synergistic effect of the three.

[0022] 3. In addition, the polyurethane adhesive system prepared in this application also contains fluorine. Fluorine gives the material hydrophobic properties and reduces the mold growth of decorative paper due to prolonged use. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] In the following specific implementation, The decorative base paper is sourced from Foshan Gaoming Jinxiangfang Decorative Materials Co., Ltd. Polypropylene glycol, with an average molecular weight of 1500; Example 1: A method for preparing flame-retardant decorative paper, comprising the following steps: (1) Preparation of branched phosphorus-containing polyols: Dipentaerythritol, (4-fluorophenyl)-phosphoric acid, and N,N-dimethylformamide were mixed and heated to react. Glycerol and potassium hydroxide were then added, and the mixture was heated to react again. After the reaction was complete, the mixture was heated to 100°C under a nitrogen atmosphere, and epifluoropropane was added and mixed. The mixture was heated again to react, yielding a branched phosphorus-containing polyol. The mass ratio of dipentaerythritol, (4-fluorophenyl)-phosphoric acid, N,N-dimethylformamide, glycerol, potassium hydroxide, and epifluoropropane was 3.5:1:10:1.5:0.09:4.5. The heating reaction conditions were: temperature 80°C, time 3 hours; the temperature rise reaction conditions were: temperature 120°C, time 2 hours, and pressure 0.10 MPa. (2) Preparation of DOPO derivatives: S1: Branched phosphorus-containing polyol, phenyl thiochloroformate, and tetramethylethylenediamine were mixed and reacted under a nitrogen atmosphere. After the reaction was completed, 1,2-propanediamine was added, and the mixture was reacted at 30°C under a vacuum of 50 Pa for 2 hours. The mixture was then distilled to obtain an amino-terminated sulfur-containing polyether. S2: An amino-terminated sulfur-containing polyether, N,N-dimethylformamide, and 3-fluoropyridine-2-aldehyde were mixed and reacted under heating. DOPO was then added, and the reaction was continued for 12 hours to obtain a DOPO derivative. In S1, the branched... The mass ratio of phosphorus-containing polyol, phenyl thiochloroformate, tetramethylethylenediamine, and 1,2-propanediamine is 1:0.55:0.32:0.7; in S1, the process conditions for the heated reaction are: temperature 140℃, time 5h; in S2, the ratio of amino-terminated sulfur-containing polyether, N,N-dimethylformamide, 3-fluoropyridine-2-aldehyde, and DOPO is 1g:15mL:1.1g:2.1g; in S2, the process conditions for the heated reaction are: temperature 90℃, time 10h. (3) Preparation of polyurethane adhesive: Isocyanate, branched phosphorus-containing polyol, 1,4-butanediol, DOPO derivative, and N,N-dimethylcyclohexylamine were mixed and heated to react. The mixture was then cooled to 50°C, and triethylamine and azobisisobutyronitrile were added. The mixture was kept at this temperature, and then deionized water and anhydrous ethanol were added. The mixture was stirred until homogeneous to obtain a polyurethane adhesive. The mass ratio of isocyanate, branched phosphorus-containing polyol, 1,4-butanediol, DOPO derivative, N,N-dimethylcyclohexylamine, triethylamine, azobisisobutyronitrile, deionized water, and anhydrous ethanol was 10:30:1.5:6:0.15:1.5:1.0:30:10. The heating reaction conditions were: temperature 85°C, time 2 hours; the holding reaction conditions were: temperature 50°C, time 2 hours. (4) Preparation of flame-retardant decorative paper: Take decorative base paper, coat the upper and lower surfaces of the base paper with polyurethane adhesive, dry to form a flame-retardant layer, and obtain flame-retardant decorative paper; the coating amount of polyurethane adhesive is 25g / m². 2 The flame retardant layer thickness is 10μm; the drying process conditions are: temperature 100℃, time 10min.

[0025] Example 2: A method for preparing flame-retardant decorative paper, comprising the following steps: (1) Preparation of branched phosphorus-containing polyols: Dipentaerythritol, (4-fluorophenyl)-phosphoric acid, and N,N-dimethylformamide were mixed and heated to react. Glycerol and potassium hydroxide were then added, and the mixture was heated to react again. After the reaction was complete, the mixture was heated to 95°C under a nitrogen atmosphere, and epifluoropropane was added and mixed. The mixture was heated again to react, yielding a branched phosphorus-containing polyol. The mass ratio of dipentaerythritol, (4-fluorophenyl)-phosphoric acid, N,N-dimethylformamide, glycerol, potassium hydroxide, and epifluoropropane was 2.5:1:8:1.0:0.08:4.0. The heating reaction conditions were: temperature 70°C, time 2.5 h; the temperature rise reaction conditions were: temperature 115°C, time 1.5 h, and pressure 0.08 MPa. (2) Preparation of DOPO derivatives: S1: Branched phosphorus-containing polyol, phenyl thiochloroformate, and tetramethylethylenediamine were mixed and reacted under a nitrogen atmosphere. After the reaction was completed, 1,2-propanediamine was added, and the mixture was reacted at 25°C under a vacuum of 50 Pa for 1.5 h. Distillation was then performed to obtain an amino-terminated sulfur-containing polyether. S2: An amino-terminated sulfur-containing polyether, N,N-dimethylformamide, and 3-fluoropyridine-2-aldehyde were mixed and reacted under heating. DOPO was then added, and the reaction was continued for 11 h to obtain a DOPO derivative. In S1, the branched... The mass ratio of phosphorus-containing polyol, phenyl thiochloroformate, tetramethylethylenediamine, and 1,2-propanediamine is 1:0.45:0.26:0.6; in S1, the process conditions for the heated reaction are: temperature 135℃, time 4h; in S2, the ratio of amino-terminated sulfur-containing polyether, N,N-dimethylformamide, 3-fluoropyridine-2-aldehyde, and DOPO is 1g:12mL:1.0g:2.0g; in S2, the process conditions for the heated reaction are: temperature 85℃, time 9h. (3) Preparation of polyurethane adhesive: Isocyanate, branched phosphorus-containing polyol, 1,4-butanediol, DOPO derivative, and N,N-dimethylcyclohexylamine were mixed and heated to react. The mixture was then cooled to 45°C, and triethylamine and azobisisobutyronitrile were added. The mixture was kept at this temperature, and then deionized water and anhydrous ethanol were added. The mixture was stirred until homogeneous to obtain a polyurethane adhesive. The mass ratio of isocyanate, branched phosphorus-containing polyol, 1,4-butanediol, DOPO derivative, N,N-dimethylcyclohexylamine, triethylamine, azobisisobutyronitrile, deionized water, and anhydrous ethanol was 10:28:1.0:4:0.10:1.0:0.55:27:8. The heating reaction conditions were: temperature 80°C, time 1.5 h; the holding reaction conditions were: temperature 45°C, time 1.5 h. (4) Preparation of flame-retardant decorative paper: Take decorative base paper, coat the upper and lower surfaces of the base paper with polyurethane adhesive, dry to form a flame-retardant layer, and obtain flame-retardant decorative paper; the coating amount of polyurethane adhesive is 20g / m². 2 The flame retardant layer thickness is 8μm; the drying process conditions are: temperature 95℃, time 8min.

[0026] Example 3: A method for preparing flame-retardant decorative paper, comprising the following steps: (1) Preparation of branched phosphorus-containing polyols: Dipentaerythritol, (4-fluorophenyl)-phosphoric acid, and N,N-dimethylformamide were mixed and heated to react. Glycerol and potassium hydroxide were then added, and the mixture was heated to react again. After the reaction was complete, under a nitrogen atmosphere, the temperature was raised to 90°C, and epifluoropropane was added and mixed. The mixture was heated again to react, yielding a branched phosphorus-containing polyol. The mass ratio of dipentaerythritol, (4-fluorophenyl)-phosphoric acid, N,N-dimethylformamide, glycerol, potassium hydroxide, and epifluoropropane was 1.5:1:6:0.5:0.05:3.5. The heating reaction conditions were: temperature 60°C, time 2 hours; the temperature rise reaction conditions were: temperature 110°C, time 1 hour, pressure 0.06 MPa. (2) Preparation of DOPO derivatives: S1: Branched phosphorus-containing polyol, phenyl thiochloroformate, and tetramethylethylenediamine were mixed and reacted under a nitrogen atmosphere. After the reaction was completed, 1,2-propanediamine was added, and the mixture was reacted at 20°C for 1 hour under a vacuum of 50 Pa. The mixture was then distilled to obtain an amino-terminated sulfur-containing polyether. S2: An amino-terminated sulfur-containing polyether, N,N-dimethylformamide, and 3-fluoropyridine-2-aldehyde were mixed and reacted under heating. DOPO was then added, and the reaction was continued for 10 hours to obtain a DOPO derivative. In S1, the branched... The mass ratio of phosphorus-containing polyol, phenyl thiochloroformate, tetramethylethylenediamine, and 1,2-propanediamine is 1:0.35:0.22:0.5; in S1, the process conditions for the heated reaction are: temperature 130℃, time 3h; in S2, the ratio of amino-terminated sulfur-containing polyether, N,N-dimethylformamide, 3-fluoropyridine-2-aldehyde, and DOPO is 1g:10mL:0.9g:1.9g; in S2, the process conditions for the heated reaction are: temperature 80℃, time 8h. (3) Preparation of polyurethane adhesive: Isocyanate, branched phosphorus-containing polyol, 1,4-butanediol, DOPO derivative, and N,N-dimethylcyclohexylamine were mixed and heated to react. The mixture was then cooled to 40°C, and triethylamine and azobisisobutyronitrile were added. The mixture was kept at this temperature, and then deionized water and anhydrous ethanol were added. The mixture was stirred until homogeneous to obtain a polyurethane adhesive. The mass ratio of isocyanate, branched phosphorus-containing polyol, 1,4-butanediol, DOPO derivative, N,N-dimethylcyclohexylamine, triethylamine, azobisisobutyronitrile, deionized water, and anhydrous ethanol was 10:25:0.5:2:0.05:0.5:0.15:25:5. The heating reaction conditions were: temperature 75°C, time 1 hour; the holding reaction conditions were: temperature 40°C, time 1 hour. (4) Preparation of flame-retardant decorative paper: Take decorative base paper, coat the upper and lower surfaces of the base paper with polyurethane adhesive, dry to form a flame-retardant layer, and obtain flame-retardant decorative paper; the coating amount of polyurethane adhesive is 15g / m². 2The flame retardant layer thickness is 6μm; the drying process conditions are: temperature 90℃, time 5min.

[0027] Comparative Example 1: Compared with Example 1, the branched phosphorus-containing polyol was replaced with polypropylene glycol, while other conditions remained unchanged. The specific steps are as follows: (1) Preparation of DOPO derivatives: S1: Polypropylene glycol, phenyl thiochloroformate, and tetramethylethylenediamine were mixed and reacted under a nitrogen atmosphere. After the reaction was completed, 1,2-propanediamine was added, and the mixture was reacted at 30°C under a vacuum of 50 Pa for 2 hours. The mixture was then distilled to obtain an amino-terminated sulfur-containing polyether. S2: An amino-terminated sulfur-containing polyether, N,N-dimethylformamide, and 3-fluoropyridine-2-aldehyde were mixed and reacted under heating. DOPO was then added, and the reaction was continued for 12 hours to obtain a DOPO derivative. In S1, polypropylene glycol... The mass ratio of diol, phenyl thiochloroformate, tetramethylethylenediamine, and 1,2-propanediamine is 1:0.55:0.32:0.7; in S1, the process conditions for the heated reaction are: temperature 140℃, time 5h; in S2, the ratio of amino-terminated sulfur-containing polyether, N,N-dimethylformamide, 3-fluoropyridine-2-aldehyde, and DOPO is 1g:15mL:1.1g:2.1g; in S2, the process conditions for the heated reaction are: temperature 90℃, time 10h. (2) Preparation of polyurethane adhesive: Isocyanate, polypropylene glycol, 1,4-butanediol, DOPO derivative, and N,N-dimethylcyclohexylamine were mixed and heated to react. The mixture was then cooled to 50°C, and triethylamine and azobisisobutyronitrile were added. The mixture was kept at this temperature, and then deionized water and anhydrous ethanol were added. The mixture was stirred until homogeneous to obtain a polyurethane adhesive. The mass ratio of isocyanate, polypropylene glycol, 1,4-butanediol, DOPO derivative, N,N-dimethylcyclohexylamine, triethylamine, azobisisobutyronitrile, deionized water, and anhydrous ethanol was 10:30:1.5:6:0.15:1.5:1.0:30:10. The heating reaction conditions were: temperature 85°C, time 2 hours; the holding reaction conditions were: temperature 50°C, time 2 hours. (3) Preparation of flame-retardant decorative paper: Take decorative base paper, coat the upper and lower surfaces of the base paper with polyurethane adhesive, dry to form a flame-retardant layer, and obtain flame-retardant decorative paper; the coating amount of polyurethane adhesive is 25g / m². 2 The flame retardant layer thickness is 10μm; the drying process conditions are: temperature 100℃, time 10min.

[0028] Comparative Example 2: Compared with Example 1, the DOPO derivative was replaced with DOPO, while all other conditions remained unchanged. The specific steps are as follows: (1) Preparation of branched phosphorus-containing polyols: Dipentaerythritol, (4-fluorophenyl)-phosphoric acid, and N,N-dimethylformamide were mixed and heated to react. Glycerol and potassium hydroxide were then added, and the mixture was heated to react again. After the reaction was complete, the mixture was heated to 100°C under a nitrogen atmosphere, and epifluoropropane was added and mixed. The mixture was heated again to react, yielding a branched phosphorus-containing polyol. The mass ratio of dipentaerythritol, (4-fluorophenyl)-phosphoric acid, N,N-dimethylformamide, glycerol, potassium hydroxide, and epifluoropropane was 3.5:1:10:1.5:0.09:4.5. The heating reaction conditions were: temperature 80°C, time 3 hours; the temperature rise reaction conditions were: temperature 120°C, time 2 hours, and pressure 0.10 MPa. (2) Preparation of polyurethane adhesive: Isocyanate, branched phosphorus-containing polyol, 1,4-butanediol, DOPO, and N,N-dimethylcyclohexylamine were mixed and heated to react. The mixture was then cooled to 50°C, and triethylamine and azobisisobutyronitrile were added. The mixture was kept at this temperature, and then deionized water and anhydrous ethanol were added. The mixture was stirred until homogeneous to obtain a polyurethane adhesive. The mass ratio of isocyanate, branched phosphorus-containing polyol, 1,4-butanediol, DOPO, N,N-dimethylcyclohexylamine, triethylamine, azobisisobutyronitrile, deionized water, and anhydrous ethanol was 10:30:1.5:6:0.15:1.5:1.0:30:10. The heating reaction conditions were: temperature 85°C, time 2 hours; the holding reaction conditions were: temperature 50°C, time 2 hours. (3) Preparation of flame-retardant decorative paper: Take decorative base paper, coat the upper and lower surfaces of the base paper with polyurethane adhesive, dry to form a flame-retardant layer, and obtain flame-retardant decorative paper; the coating amount of polyurethane adhesive is 25g / m². 2 The flame retardant layer thickness is 10μm; the drying process conditions are: temperature 100℃, time 10min.

[0029] Comparative Example 3: Compared with Example 1, the branched phosphorus-containing polyol was replaced with polypropylene glycol, and the DOPO derivative was replaced with DOPO, while the other conditions remained unchanged. The specific steps are as follows: (1) Preparation of polyurethane adhesive: Isocyanate, polypropylene glycol, 1,4-butanediol, DOPO, and N,N-dimethylcyclohexylamine were mixed and heated to react. The mixture was then cooled to 50°C, and triethylamine and azobisisobutyronitrile were added. The mixture was kept at this temperature, and then deionized water and anhydrous ethanol were added. The mixture was stirred until homogeneous to obtain a polyurethane adhesive. The mass ratio of isocyanate, polypropylene glycol, 1,4-butanediol, DOPO, N,N-dimethylcyclohexylamine, triethylamine, azobisisobutyronitrile, deionized water, and anhydrous ethanol was 10:30:1.5:6:0.15:1.5:1.0:30:10. The heating reaction conditions were: temperature 85°C, time 2 hours; the holding reaction conditions were: temperature 50°C, time 2 hours. (2) Preparation of flame-retardant decorative paper: Take decorative base paper, coat the upper and lower surfaces of the base paper with polyurethane adhesive, dry to form a flame-retardant layer, and obtain flame-retardant decorative paper; the coating amount of polyurethane adhesive is 25g / m². 2 The flame retardant layer thickness is 10μm; the drying process conditions are: temperature 100℃, time 10min.

[0030] Experiment: The flame-retardant decorative paper obtained in Examples 1-3 and Comparative Examples 1-3 was tested for its performance; Combustion performance: The combustion performance rating of flame-retardant decorative paper was tested in accordance with GB 8624-2012; Water absorption rate: The water absorption of flame-retardant decorative paper was tested according to GB / T 461.3-2005; The table below shows the performance test results of flame-retardant decorative paper; Based on the table above, the following conclusions can be drawn; Compared with Example 1, Comparative Example 1 replaced the branched phosphorus-containing polyol with polypropylene glycol. The fire performance rating of the decorative paper decreased and the water absorption rate increased significantly. This is because the phosphorus-containing polyol is made from (4-fluorophenyl)-phosphoric acid, dipentaerythritol and epifluoropropane. Its molecular structure contains fluorine and phosphorus, and it has certain hydrophobicity and flame retardancy. Compared with Example 1, Comparative Example 2 replaced DOPO derivative with DOPO, resulting in a decrease in the flammability rating and an increase in water absorption rate of the decorative paper. This is because although DOPO has certain flame retardancy, the flame retardancy of phosphorus alone is limited. Therefore, by reacting branched phosphorus-containing polyols, phenyl thiochloroformate, and 1,2-propanediamine, a terminal amino-containing sulfur-containing polyether containing phosphorus and sulfur is prepared. Then, by utilizing the phosphorus-hydrogen bond reaction between the amino group and DOPO, a DOPO derivative containing phosphorus, nitrogen, sulfur, and fluorine is obtained, thereby comprehensively improving the flame retardancy and hydrophobicity of the decorative paper. Compared with Example 1, Comparative Example 3 replaced the branched phosphorus-containing polyol with polypropylene glycol and replaced the DOPO derivative with DOPO. The flame performance rating of the decorative paper decreased and the water absorption rate increased. This shows that the branched phosphorus-containing polyol and DOPO derivative prepared in this application can comprehensively improve the flame retardancy of the decorative paper, while also giving it a certain degree of hydrophobicity, reducing the occurrence of mildew after long-term use, and extending its service life.

[0031] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for preparing flame-retardant decorative paper, characterized in that: Includes the following steps: Take decorative base paper, coat the upper and lower surfaces of the decorative base paper with polyurethane adhesive, dry it to form a flame retardant layer, and obtain flame retardant decorative paper. The preparation process of the polyurethane adhesive is as follows: Isocyanate, branched phosphorus-containing polyol, 1,4-butanediol, DOPO derivative, and N,N-dimethylcyclohexylamine are mixed and heated to react. The mixture is then cooled to 40-50°C, and triethylamine and azobisisobutyronitrile are added. The mixture is kept at this temperature and then deionized water and anhydrous ethanol are added. The mixture is stirred until homogeneous to obtain a polyurethane adhesive.

2. The method for preparing flame-retardant decorative paper according to claim 1, characterized in that: The branched phosphorus-containing polyol is obtained by the following process: Dipentaerythritol, (4-fluorophenyl)-phosphoric acid, and N,N-dimethylformamide were mixed and heated to react. Then, glycerol and potassium hydroxide were added and heated to react. After the reaction was completed, under a nitrogen atmosphere, the temperature was raised to 90-100°C, and epifluoropropane was added and mixed. The temperature was raised again to react to obtain branched phosphorus-containing polyol.

3. The method for preparing a flame-retardant decorative paper according to claim 1, characterized in that: The DOPO derivative is prepared by the following process: S1: Branched phosphorus-containing polyol, phenyl thiochloroformate, and tetramethylethylenediamine are mixed and reacted under nitrogen atmosphere. After the reaction is completed, 1,2-propanediamine is added and reacted at 20-30℃ for 1-2 hours under vacuum of 50 Pa. The mixture is then distilled to obtain amino-terminated sulfur-containing polyether. S2: Mix amino-terminated sulfur-containing polyether, N,N-dimethylformamide, and 3-fluoropyridine-2-aldehyde, heat to react, then add DOPO, and continue the reaction for 10-12 hours to obtain the DOPO derivative.

4. The method for preparing flame-retardant decorative paper according to claim 1, characterized in that: The mass ratio of isocyanate, branched phosphorus-containing polyol, 1,4-butanediol, DOPO derivative, N,N-dimethylcyclohexylamine, triethylamine, azobisisobutyronitrile, deionized water, and anhydrous ethanol is 10:(25~30):(0.5~1.5):(2~6):(0.05~0.15):(0.5~1.5):(0.15~1.0):(25~30):(5~10).

5. The method for preparing flame-retardant decorative paper according to claim 2, characterized in that: The mass ratio of dipentaerythritol, (4-fluorophenyl)-phosphoric acid, N,N-dimethylformamide, glycerol, potassium hydroxide, and epifluoropropane is (1.5~3.5):1:(6~10):(0.5~1.5):(0.05~0.09):(3.5~4.5).

6. The method for preparing a flame-retardant decorative paper according to claim 3, characterized in that: In S1, the mass ratio of branched phosphorus-containing polyol, phenyl thiochloroformate, tetramethylethylenediamine, and 1,2-propanediamine is 1:(0.35~0.55):(0.22~0.32):(0.5~0.7). In S2, the ratio of amino-terminated sulfur-containing polyether, N,N-dimethylformamide, 3-fluoropyridine-2-aldehyde, and DOPO is 1g:(10~15)mL:(0.9~1.1)g:(1.9~2.1)g.

7. The method for preparing flame-retardant decorative paper according to claim 1, characterized in that: The coating amount of the polyurethane adhesive is 15~25g / m². 2 ; The thickness of the flame-retardant layer is 6~10μm.

8. The method for preparing a flame-retardant decorative paper according to claim 1, characterized in that: The process conditions for the heating reaction are: temperature 75~85℃, time 1~2h; The process conditions for the heat preservation reaction are: temperature 40~50℃, time 1~2h.

9. The method for preparing flame-retardant decorative paper according to claim 2, characterized in that: The process conditions for the heating reaction are: temperature 60~80℃, time 2~3h; The process conditions for the heating reaction are: temperature 110~120℃, time 1~2h, and pressure 0.06~0.10MPa.

10. A flame-retardant decorative paper, characterized in that: The preparation method according to any one of claims 1 to 9 is used.

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