Environmentally friendly decorative paper and preparation method thereof

Abstract

The invention discloses an environmentally friendly decorative paper and a preparation method thereof. The environmentally friendly decorative paper comprises modified starch, cellulose, a stabilizer and an antibacterial agent. The invention utilizes isocyanic acid in the modifier to react with hydroxyl groups in starch to generate carbamate functional groups, thereby obtaining modified starch, and then cross-linking the modified starch with the stabilizer, cellulose and the antibacterial agent to prepare the environmentally friendly decorative paper. The amino group and hydroxyl group in the modified starch interact with the free sulfonic acid group and hydroxyl group in the stabilizer and the hydroxyl group in the cellulose to form a rich hydrogen bond network, thereby enhancing the thermal stability of the decorative paper. Compared with the prior art, the environmentally friendly decorative paper prepared by the invention has the advantages of good water vapor and oxygen barrier properties and good ultraviolet barrier properties.

Description

Technical Field

[0001] The invention relates to the field of decorative paper, and in particular to an environmentally friendly decorative paper and a preparation method thereof. Background Art

[0002] As people's awareness of environmental protection continues to increase, the demand for decorative paper is gradually changing. Traditional decorative paper often uses a lot of chemicals and additives in the production process, which causes certain harm to the environment and human health. Perfluoroalkyl substances and petroleum-based raw materials have been used to improve the physical properties, appearance or printing performance of decorative paper. Although they are paper coatings for paper, their use is also restricted due to health and sustainability issues.

[0003] Decorative paper is also widely used in the home furnishing field. It can be used to decorate the surface of furniture, such as wardrobes, bedside tables, desks, etc. Decorative paper also has important applications in the building materials industry. It can be used as a finishing material for building panels, such as low-pressure panels, high-pressure panels, and fireproof panels used in furniture and cabinets. Decorative paper plays a decorative role in providing patterns and a covering role in preventing the bottom glue from seeping through these products. At the same time, decorative paper also has good hiding power, impregnation and printing properties, which can meet the requirements of building materials products for surface decoration and performance.

[0004] At present, during the rainy season, due to the high humidity in the air, the furniture, floors, door frames, cabinets in the home are easily affected by moisture. A long-term humid environment will easily breed bacteria or mold, thus affecting the service life of these furniture; similarly, in the summer, because the furniture is still exposed to sunlight, the surface coating will fade, thus affecting the overall appearance and service life of the home.

[0005] CN108130808B discloses a flame-retardant veneer decorative paper and a flame-retardant veneer artificial board using the decorative paper. The veneer decorative paper is prepared by the following method: 1) softwood pulp and hardwood pulp are pulped separately, mixed and dispersed, titanium dioxide dispersion, retention aid, wet strength agent and modified starch paste are added to prepare base paper; 2) silica sol is used to double-side coat the base paper to obtain modified paper A; 3) borax solution is used to impregnate the modified paper A to obtain modified paper B; 4) soybean protein glue is used to double-side coat the modified paper B with glue, and the glue amount is 12-15g / m 2 The obtained veneer decorative paper is coated with silica sol and impregnated with borax solution to add flame retardant to the paper, which improves the limiting oxygen index of the decorative paper and the ignition time of the veneer artificial board, and has a good effect of preventing the expansion and spread of fire. However, the veneer decorative paper prepared by this method has poor mechanical properties and is prone to cracks or slip marks.

[0006] CN113273582A discloses a novel antibacterial and antiviral preparation, resin, decorative paper and board material, which is prepared by catalyzing the ring opening of ethylene oxide to obtain polyether alkali metal salt, and then catalyzing the ring opening of 1,3-propane sultone to obtain polyether sulfonate, which is compounded with antifungal agent and plant extract to prepare antibacterial and antiviral preparation, and then the proportion of each component is reasonably adjusted to synthesize melamine formaldehyde resin, so that the resin and the preparation are compatible, and the board material with antibacterial and antiviral efficacy is prepared by using the dipping process and high temperature and high pressure pressing process. However, the decorative paper prepared by this method will accelerate the damage time and shorten the service life when used under sunlight for a long period of time. Summary of the invention

[0007] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to improve the water vapor and oxygen barrier properties and ultraviolet barrier properties of the environmentally friendly decorative paper.

[0008] To achieve the above object, the present invention provides an environmentally friendly decorative paper, comprising: modified starch, cellulose, a stabilizer and an antibacterial agent, wherein the modified starch is prepared from starch and the modifier.

[0009] Preferably, the method for preparing the modified starch comprises the following steps:

[0010] S1, dissolving starch, a modifier and sulfuric acid in anhydrous ethanol, grinding and stirring to obtain a mixture;

[0011] S2. Heat the mixture in S1 at 130-170° C. for 1-3 h, centrifuge, wash, and dry to obtain modified starch.

[0012] Preferably, the method for preparing the modified starch comprises the following steps, in parts by weight:

[0013] S1, dissolving 5-20 parts of starch, 1-6 parts of modifier, and 0.1-3 parts of sulfuric acid in 1-10 parts of anhydrous ethanol, grinding 1-3 times, and stirring for 5-10 minutes to obtain a mixture;

[0014] S2. Heat the mixture in S1 at 130-170° C. for 1-3 h, centrifuge, wash to obtain a precipitate, and dry at room temperature for 20-40 min to obtain modified starch.

[0015] Preferably, the modifier is any one of nicotinoyl isocyanate, benzenesulfonyl isocyanate, 4-phenoxyphenyl isocyanate, and 3-(isocyanatomethyl)benzoic acid.

[0016] More preferably, the modifier is 3-(isocyanatomethyl)benzoic acid.

[0017] Preferably, the cellulose is cellulose acetate.

[0018] Preferably, the stabilizer is meclocycline sulfosalicylate.

[0019] Preferably, the antibacterial agent is nanosilver.

[0020] Preferably, the starch is any one of cereal starch and bean starch.

[0021] A method for preparing environmentally friendly decorative paper comprises the following steps, measured in parts by weight:

[0022] Step 1: Add 1-4 parts of 0.01-1 g / mL silver nitrate solution to 0.4 wt% starch solution under the condition of avoiding light, and then add 1-5 parts of 0.1-0.5 g / mL sodium citrate solution, and stir at 60-90° C. for 30-60 min to obtain nanosilver;

[0023] Step 2: add 1-8 parts of modified starch, 0.2-3 parts of stabilizer, and 1-15 parts of cellulose to 25-80 parts of water, add 1-5 parts of glycerol, stir for 30-60 minutes under heating in a water bath at 80-96° C., then add 5-18 parts of nanosilver prepared in step 1, and ultrasonicate at 1500-2000 KHz for 1-3 hours to obtain a coating;

[0024] Step 3: Take the coating in step 2, fix the filter paper on the glass plate by rod coating, apply the coating on the filter paper, place the coated paper sample in an oven at 95-105°C, and dry for 10-15 minutes to obtain environmentally friendly decorative paper.

[0025] In this recipe, the ingredients and their functions are as follows:

[0026] Starch: Starch is one of the raw materials for synthesizing modified starch. Starch is abundant in sources, biodegradable, low-cost and environmentally friendly. Starch is usually composed of two macromolecular polymers, amylose and amylopectin. These two molecular chains contain a large number of reactive hydroxyl groups, which provide excellent molecular structure conditions for starch modification.

[0027] Modifier: Modifier is one of the raw materials for synthesizing modified starch. The modifier contains isocyanic acid, and carbamate starch is obtained by the addition reaction of isocyanic acid in the modifier with the hydroxyl group in starch. The carbamate functional group introduces ester groups and larger functional groups on the starch molecule, which can increase the hydrophobicity of starch-based materials and improve the solubility of starch in low-polarity solvents. In terms of thermal properties, compared with the molecular structure of unmodified starch, the steric hindrance between the molecular chains of carbamate starch increases, resulting in an increase in the glass transition temperature. Most carbamate starches have better thermal stability and higher decomposition temperatures than natural starch. In terms of viscosity, carbamate starch affects the hydrophilicity of starch and the formation of hydrogen bonds through spatial interactions between starch chains, thereby affecting viscosity. Therefore, the carbamate group has the characteristics of hygroscopicity and internal plasticization. At the same time, the carbamate functional group contains amide groups, which have the ability to complex with heavy metal ions, and therefore have the functions of adsorption and flocculation.

[0028] Sulfuric acid: Sulfuric acid can act as a catalyst in the reaction to promote the reaction between starch and modifier.

[0029] Anhydrous ethanol: As a solvent, anhydrous ethanol can dissolve starch and modifiers, allowing them to be fully mixed and promoting the chemical reaction. At the same time, during the heating and stirring process, anhydrous ethanol helps to reduce the viscosity of the mixture.

[0030] Cellulose: As one of the raw materials for synthetic coatings, nanocellulose with high specific surface area and high aspect ratio prepared from cellulose has better film-forming properties. It uses biological substrates as raw materials and has good environmental protection effects.

[0031] Stabilizer: As one of the raw materials for synthetic coatings, the aromatic ring structural unit with UV absorption ability in the stabilizer structure plays a very important role. In addition, the UV absorption of stabilizers with large molecular weight can be transferred to higher wavelengths, thereby blocking more ultraviolet rays.

[0032] Antimicrobial agents: Antimicrobial agents can enhance the antimicrobial effect in coatings, thereby effectively inhibiting bacterial growth, improving hygiene safety, preventing odor and mildew, and enhancing antimicrobial properties, thereby improving the quality and performance of decorative paper.

[0033] Sodium citrate: During the preparation process, sodium citrate can also prevent the oxidation of nanosilver and ensure the stability of nanosilver.

[0034] Beneficial effects of the present invention:

[0035] 1. Compared with the prior art, the present invention utilizes the isocyanate contained in the modifier to react with the hydroxyl group in the starch to obtain the modified starch, and the carbamate group contained in the modified starch has the characteristics of hygroscopicity and internal plasticization, which can improve the water dispersibility and hydrophilicity of the modified starch.

[0036] 2. Compared with the prior art, the amine groups in the modified starch can interact with the hydroxyl groups in cellulose. At the same time, the hydroxyl groups and amino groups in the modified starch can also form abundant hydrogen bonds with the free sulfonic acid groups and hydroxyl groups in the stabilizer, thereby increasing the mechanical properties of the decorative paper. The rigid structure of the aromatic hydrocarbons in the stabilizer can improve the tensile strength of the decorative paper. The groups with ultraviolet absorption characteristics contained in the stabilizer can improve the anti-ultraviolet performance of the decorative paper. DETAILED DESCRIPTION

[0037] Parameters for specific chemical substances used, sources.

[0038] Pea starch, Jinan Yuncheng Biotechnology Co., Ltd.

[0039] Meclizine sulfosalicylate, CAS number: 73816-42-9.

[0040] Cellulose acetate, model: CB2311, Wuhan Lvjing Fenghua Biotechnology Co., Ltd.

[0041] Nanocellulose fiber, 20 nm, Hubei Yamade Biomedicine Co., Ltd.

[0042] Nicotinoyl isocyanate, CAS number: 26971-98-2.

[0043] Benzenesulfonyl isocyanate, CAS number: 2845-62-7.

[0044] 4-Phenoxyphenyl isocyanate, CAS number: 59377-19-4.

[0045] 3-(Isocyanatomethyl)benzoic acid, English: 3-(Isocyanatomethyl)benzoic acid, CAS number: 1258540-37-2.

[0046] Example 1

[0047] A method for preparing environmentally friendly decorative paper comprises the following steps:

[0048] Step 1: In the dark, add 1.5 mL of 0.05 g / mL silver nitrate aqueous solution to 10 g of 0.4 wt% pea starch aqueous solution, then add 2 mL of 0.1 g / mL sodium citrate aqueous solution, and stir at 78° C. for 50 min to obtain nanosilver;

[0049] Step 2: Add 5 g of modified starch, 1 g of meclizine sulfosalicylate, and 12 g of cellulose acetate to 45 mL of water, add 2.5 g of glycerol, stir for 50 min in a 95° C. water bath, add 15 g of the nanosilver prepared in step 1, and ultrasonicate at 1500 Hz for 1 h to obtain a coating;

[0050] Step 3: Take the coating in step 2 and apply it on an automatic coating machine using a rod coating method. Fix the filter paper on a glass plate and apply the coating on the filter paper using a No. 20 coating rod. Place the coated paper sample in an oven at 105°C and dry for 12 minutes to obtain environmentally friendly decorative paper.

[0051] Wherein, the preparation method of the modified starch comprises the following steps:

[0052] S1, adding 10 g of pea starch, 3 g of 3-(isocyanatomethyl)benzoic acid, and 0.3 mL of 1.5 wt% sulfuric acid to 3 mL of anhydrous ethanol, grinding once, and stirring at 200 rpm for 6 min to obtain a mixture;

[0053] S2. The mixture in S1 was heated at 150° C. for 2 h, centrifuged at 6000 rpm, washed with 70 wt % ethanol aqueous solution to obtain a precipitate, and dried at 25° C. for 30 min to obtain modified starch.

[0054] Example 2

[0055] The difference between Example 2 of the present application and Example 1 is that the 3-(isocyanatomethyl)benzoic acid in S1 is replaced by nicotinoyl isocyanate.

[0056] Example 3

[0057] The difference between Example 3 of the present application and Example 1 is that the 3-(isocyanatomethyl)benzoic acid in S1 is replaced by benzenesulfonyl isocyanate.

[0058] Example 4

[0059] The difference between Example 4 of the present application and Example 1 is that the 3-(isocyanatomethyl)benzoic acid in S1 is replaced by 4-phenoxyphenyl isocyanate.

[0060] Comparative Example 1

[0061] The difference between Comparative Example 1 of the present application and Example 1 is that the meclizine sulfosalicylate in step 2 is replaced by calcium lignin sulfonate.

[0062] Comparative Example 2

[0063] The difference between Comparative Example 2 of the present application and Example 1 is that the cellulose acetate in step 2 is replaced by nanocellulose fibers.

[0064] Comparative Example 3

[0065] The difference between Comparative Example 3 of the present application and Example 1 is that the 3-(isocyanatomethyl)benzoic acid in S1 is replaced by urea.

[0066] Test Example 1

[0067] Barrier performance test: Barrier performance test includes water vapor barrier performance test and oxygen barrier performance test. The water vapor barrier performance test is tested in accordance with GB / T 1037-2021 "Determination of water vapor permeability of plastic films and sheets - Cup weight gain and weight loss method", and the oxygen barrier performance is tested in accordance with GB / T 1038.1-2022 "Plastic film and sheet gas permeability test method Part 1: Differential pressure method". The test results are shown in Table 1:

[0068] Table 1 Barrier performance test

[0069]

[0070] Test Example 2

[0071] UV blocking performance test: GB / T 33327-2016 "Evaluation of storage stability of ultraviolet curing coatings" was used at wavelengths of 200 and 400 nm, and the decorative papers prepared in Examples 1-4 and Comparative Examples 1-3 were studied using an ultraviolet visible spectrometer (UV-2600). The test results are shown in Table 2:

[0072] Table 2 UV blocking performance test

[0073]

[0074]

[0075] By comparing with Examples 1-4 and Comparative Examples 1-3, it can be found that the decorative paper prepared in Example 1 is better in barrier performance and UV barrier performance tests. The difference between Examples 1-4 and Comparative Example 3 is that different modifiers are used. The possible reason is that compared with these modifiers, the modifier in Example 1 contains a carboxyl functional group in addition to an isocyanate functional group. Therefore, in addition to the isocyanate in the modifier being able to react with the hydroxyl group in the starch to form a carbamate, the carboxyl functional group also reacts with the hydroxyl group in the starch to form a carbamate bond, which has a resistance to degradation pathways such as hydrolysis, etc., so that the prepared decorative paper is more tightly cross-linked, thereby showing excellent water vapor and oxygen barrier properties and mechanical properties.

[0076] Compared with Example 1, the difference between Example 1 and Comparative Example 1 is that different stabilizers are used. Among them, the stabilizer used in Example 1 contains an amine functional group in addition to the phenolic hydroxyl group and sulfonate group that absorb ultraviolet rays. The amine functional group can further cross-link with the hydroxyl group in carbamate starch or the hydroxyl group in starch, increasing the cross-linking degree of the polymer and increasing the water vapor and oxygen barrier properties of the decorative paper. At the same time, possibly due to the difference in spatial position and carbonyl group, the stabilizer in Example 1 also exhibits good ultraviolet barrier properties.

[0077] Compared with Example 1 and Comparative Example 2, the difference is that different celluloses are used, wherein the cellulose used in Example 1 has better hydrophilicity, porosity, high specific surface area and good swelling property in addition to good biocompatibility and degradability. Moreover, cellulose acetate is a semi-crystalline polymer with an orderly molecular structure, which provides a good physical barrier for the decorative paper. When water vapor or oxygen tries to pass through the coating, they need to pass through this orderly molecular structure and are effectively blocked. Although the nanocellulose fibers are tiny in size, due to their disordered arrangement structure, it is difficult to provide a physical barrier like cellulose acetate. Therefore, the decorative paper prepared in Example 1 will show better water vapor and oxygen barrier properties and UV barrier properties.

Claims

1. A method for preparing an environmentally friendly decorative paper, characterized in that: The method comprises the following steps, in parts by weight: Step 1: Add 1-4 parts of 0.01-1 g / mL silver nitrate solution to 0.4 wt% starch solution under the condition of avoiding light throughout the process, and then add 1-5 parts of 0.1-0.5 g / mL sodium citrate solution, and stir at 60-90° C. for 30-60 min to obtain nanosilver; Step 2: add 1-8 parts of modified starch, 0.2-3 parts of stabilizer, and 1-15 parts of cellulose to 25-80 parts of water, add 1-5 parts of glycerol, stir for 30-60 minutes under heating in a water bath at 80-96° C., then add 5-18 parts of nanosilver prepared in step 1, and ultrasonicate at 1500-2000 KHz for 1-3 hours to obtain a coating; Step 3: Take the coating in step 2, fix the filter paper on the glass plate by rod coating, apply the coating on the filter paper, place the coated paper sample in an oven at 95-105°C, and dry for 10-15 minutes to obtain environmentally friendly decorative paper; The preparation method of the modified starch comprises the following steps, measured in parts by weight: S1. Add 5-20 parts of starch, 1-6 parts of modifier, and 0.1-3 parts of sulfuric acid to 1-10 parts of anhydrous ethanol, grind 1-3 times, and stir for 5-10 minutes to obtain a mixture; S2, heating the mixture in S1 at 130-170° C. for 1-3 h, centrifuging, washing to obtain a precipitate, and drying at room temperature for 20-40 min to obtain a modified starch; The modifier is 3-(isocyanatomethyl)benzoic acid; The cellulose is cellulose acetate; The stabilizer is meclizine sulfosalicylate.

2. The method for preparing the environmentally friendly decorative paper according to claim 1, characterized in that: The starch is any one of cereal starch and bean starch.

3. An environmentally friendly decorative paper, characterized in that Prepared by the method according to claim 1 or 2.

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