An efficient antibacterial decorative veneer and its preparation method

Abstract

The present invention provides an efficient antibacterial decorative veneer and a preparation method thereof. The preparation method includes: impregnating a veneer with an impregnating solution containing melamine formaldehyde resin and then drying it to obtain the antibacterial decorative veneer; wherein, the melamine formaldehyde resin is obtained by carrying out a polycondensation reaction on raw materials including formaldehyde, melamine and a modifier, and the modifier is a composite material of chitosan quaternary ammonium salt loaded with nano-TiO₂. The efficient antibacterial decorative veneer provided by the present invention not only has excellent antibacterial properties, but also has a self-cleaning function.

Description

Technical Field

[0001] The present invention relates to the technical field of wood processing, and particularly to a highly efficient antibacterial decorative veneer and a preparation method thereof. Background Art

[0002] Existing melamine formaldehyde resin impregnated products mainly impregnate ordinary decorative papers, and a small number also use the impregnation process of decorative papers to impregnate products such as wood veneers and thin veneers to obtain decorative veneers.

[0003] With the continuous development of China's decorative material industry, decorative veneers are well-known to the public. They not only alleviate the supply-demand contradiction of precious woods in China, but also have a much better decorative effect than ordinary impregnated paper facings and PVC facings. However, due to the nature of wood, decorative veneers are porous materials with anisotropy and are prone to adsorbing moisture in the air. Therefore, the surface of wood products made of decorative veneers is prone to bacterial growth, affecting their service life and increasing the cost of later management.

[0004] At present, it is of great significance to endow artificial decorative veneers with antibacterial and other properties through chemical or physical modification of their surfaces. Summary of the Invention

[0005] Based on the technical problems existing in the background art, the present invention provides a highly efficient antibacterial decorative veneer and a preparation method thereof. The decorative veneer not only has excellent antibacterial properties, but also has a self-cleaning function.

[0006] A preparation method of a highly efficient antibacterial decorative veneer provided by the present invention includes: impregnating a veneer with an impregnating solution including melamine formaldehyde resin and then drying to obtain the antibacterial decorative veneer;

[0007] Wherein, the melamine formaldehyde resin is obtained by carrying out a polycondensation reaction on raw materials including formaldehyde, melamine and a modifier, and the modifier is a composite material of chitosan quaternary ammonium salt loaded with nano-TiO₂.

[0008] Preferably, the composite material of chitosan quaternary ammonium salt loaded with nano-TiO₂ is prepared by the following method:

[0009] Adding an ethanol dispersion of tetrabutyl titanate to an aqueous solution of chitosan quaternary ammonium salt, stirring and reacting, filtering, and drying to remove water to obtain the composite material of chitosan quaternary ammonium salt loaded with nano-TiO₂.

[0010] Preferably, the weight ratio of tetrabutyl titanate to chitosan quaternary ammonium salt is 15-30:1.

[0011] Preferably, the melamine formaldehyde resin is prepared by the following method:

[0012] After adjusting the aqueous solution of formaldehyde to a pH value of 9.0 - 9.5 with sodium hydroxide solution, melamine and a modifier are added. The temperature is raised to 85 - 95 °C within 35 - 45 min, and after holding the reaction for 30 - 40 min, the temperature is lowered to 60 - 70 °C. Then sodium tetraborate is added, and after holding the reaction for 10 - 15 min, the pH value is adjusted to 8.0 - 8.5 with sodium hydroxide solution. After cooling to no more than 40 °C, the material is discharged to obtain the melamine - formaldehyde resin.

[0013] Preferably, the molar ratio of formaldehyde to melamine is 1.8 - 2.0:1, the dosage of the modifier is 12 - 19 wt% of melamine, and the dosage of sodium tetraborate is 1 - 3 wt% of melamine.

[0014] Preferably, the solid content of the melamine - formaldehyde resin is 51 - 58 wt%.

[0015] Preferably, the impregnating solution further includes a curing agent;

[0016] Preferably, the curing agent is triethanolamine and / or hexamethylenetetramine, and its dosage is 0.3 - 1 wt% of the melamine - formaldehyde resin.

[0017] Preferably, after impregnating the veneer with the impregnating solution containing the melamine - formaldehyde resin, it is dried. The resin uptake of the veneer is 100 - 120%, the drying temperature is 90 - 120 °C, and the time is 60 - 120 s.

[0018] Preferably, before impregnating the veneer with the impregnating solution containing the melamine - formaldehyde resin, the veneer is pretreated;

[0019] Preferably, the pretreatment includes: after sanding the veneer, soaking it in a weakly alkaline solution for 10 - 15 min.

[0020] The present invention also provides a highly antibacterial decorative veneer, which is prepared by the above - mentioned preparation method.

[0021] The high-efficiency antibacterial decorative veneer proposed by the present invention is obtained by impregnating the veneer with an impregnating solution containing melamine formaldehyde resin and then drying it. Since the melamine formaldehyde resin used in this impregnating solution is obtained by the polycondensation reaction of formaldehyde, melamine and a modifier, and the modifier used is a composite material of chitosan quaternary ammonium salt loaded with nano-TiO₂, therefore, on the one hand, a large number of hydroxyl groups are contained in the chitosan quaternary ammonium salt molecules, which can form polycondensation with the melamine formaldehyde resin, so that the chitosan quaternary ammonium salt can be evenly distributed in the melamine formaldehyde resin as a bacteriostatic agent; compared with directly adding a common antibacterial agent to the melamine formaldehyde resin, the latter has poor antibacterial effect due to problems such as layering and precipitation of the added antibacterial agent, while the former can effectively play an antibacterial role because the antibacterial agent can be well dispersed therein; on the other hand, since the composite material of chitosan quaternary ammonium salt loaded with nano-TiO₂ is prepared by reacting chitosan quaternary ammonium salt with tetrabutyl titanate, and the chitosan quaternary ammonium salt can adsorb tetrabutyl titanate, so when the two react, TiO₂ after the hydrolysis of tetrabutyl titanate can be evenly distributed on the surface of the chitosan quaternary ammonium salt. When the chitosan quaternary ammonium salt is evenly distributed in the melamine formaldehyde resin, the TiO₂ loaded on it is also well dispersed in the melamine formaldehyde resin, so that TiO₂ can also be distributed on the surface of the veneer impregnated with this melamine formaldehyde resin. Considering the photocatalytic activity of TiO₂, it can not only further enhance the antibacterial effect, but also catalytically degrade organic pollutants and has a self-cleaning function. Detailed implementation mode

[0022] Next, the technical solution of the present invention will be described in detail through specific examples. However, it should be clearly stated that these examples are used for illustration only and are not construed as limiting the scope of the present invention.

[0023] Example 1

[0024] A high-efficiency antibacterial decorative veneer, and its preparation method includes:

[0025] (1) An impregnating solution including melamine formaldehyde resin

[0026] Add an aqueous formaldehyde solution with a concentration of 37 wt% to the reaction kettle according to the feeding ratio of formaldehyde to melamine of 1.9:1 mol / mol. Start the stirrer, add a sodium hydroxide solution with a concentration of 30 wt% under stirring conditions to adjust the pH value to 9.5, then add 100 parts by weight of melamine and 16 parts by weight of the modifier, heat up to 90 °C within 40 min, keep the temperature for reaction for 30 min, cool down to 65 °C and then add 2 parts by weight of sodium tetraborate, keep the temperature for reaction for 15 min, add a sodium hydroxide solution with a concentration of 30 wt% to adjust the pH value to 8.0, and discharge the material after cooling down to 40 °C to obtain the melamine formaldehyde resin, and control its solid content to be 54 wt%;

[0027] Among them, the modifier is a composite material of chitosan quaternary ammonium salt loaded with nano-TiO₂, which is prepared by the following method: Dissolve 1 part by weight of chitosan (deacetylation degree ≥ 80%) in an acetic acid aqueous solution (0.5 mol / L), adjust the pH value to 6.0 with a 5 wt% sodium hydroxide solution, add an anhydrous ethanol solution containing 21 parts by weight of tetrabutyl titanate, stir and react at room temperature for 6 h, centrifuge to separate the powder, and dry to remove water at 100 °C to obtain the composite material of chitosan quaternary ammonium salt loaded with nano-TiO₂, which is the modifier;

[0028] Here, the chitosan quaternary ammonium salt is prepared by reacting chitosan and 2,3-epoxypropyltrimethylammonium chloride in a weight ratio of 1:2. Specifically, chitosan and 2,3-epoxypropyltrimethylammonium chloride are added to deionized water and stirred and reacted at 70 °C to obtain;

[0029] Add 0.5 part by weight of triethanolamine to 100 parts by weight of the above melamine formaldehyde resin, stir and mix evenly to obtain an impregnating solution containing melamine formaldehyde resin;

[0030] (2) High-efficiency antibacterial decorative veneer

[0031] Cut poplar into 0.1 mm thick and then sand it, and then soak it in a 3 wt% sodium hydroxide solution for 10 min to obtain the pretreated veneer; Immerse the pretreated veneer in the above impregnating solution containing melamine formaldehyde resin, with an impregnation amount of 113%, and then place it in an oven and dry it at 110 °C to obtain the high-efficiency antibacterial decorative veneer, with a volatile content of 11% and a pre-curing degree of 36%.

[0032] Example 2

[0033] A high-efficiency antibacterial decorative veneer, the preparation method of which includes:

[0034] (1) Impregnating solution containing melamine formaldehyde resin

[0035] Add an aqueous formaldehyde solution with a concentration of 37 wt% to the reaction kettle according to the feed ratio of formaldehyde to melamine of 1.8:1 mol / mol, start the stirrer, add a 30 wt% sodium hydroxide solution to adjust the pH value to 9.5 under stirring conditions, then add 100 parts by weight of melamine and 12 parts by weight of the modifier, raise the temperature to 85 °C within 35 min, keep the temperature for reaction for 30 min, lower the temperature to 70 °C, add 1 part by weight of sodium tetraborate, keep the temperature for reaction for 10 min, add a 30 wt% sodium hydroxide solution to adjust the pH value to 8.5, and discharge the material after lowering the temperature to 40 °C to obtain the melamine formaldehyde resin, and control its solid content to be 58 wt%;

[0036] Among them, the modifier is a composite material of chitosan quaternary ammonium salt loaded with nano-TiO₂, which is prepared by the following method: Dissolve 1 part by weight of chitosan (deacetylation degree ≥ 80%) in an acetic acid aqueous solution (0.5 mol / L), adjust the pH value to 6.0 with a 5 wt% sodium hydroxide solution, add an anhydrous ethanol solution containing 15 parts by weight of tetrabutyl titanate, stir and react at room temperature for 6 h, centrifuge to separate the powder, and dry to remove water at 100 °C to obtain the composite material of chitosan quaternary ammonium salt loaded with nano-TiO₂, which is the modifier;

[0037] Here, the chitosan quaternary ammonium salt is prepared by reacting chitosan and 2,3-epoxypropyltrimethylammonium chloride in a weight ratio of 1:2. Specifically, chitosan and 2,3-epoxypropyltrimethylammonium chloride are added to deionized water and stirred and reacted at 70 °C to obtain;

[0038] Add 0.3 part by weight of hexamethylenetetramine to 100 parts by weight of the above melamine formaldehyde resin, stir and mix evenly to obtain an impregnating solution containing melamine formaldehyde resin;

[0039] (2) High-efficiency antibacterial decorative veneer

[0040] Slice poplar wood to a thickness of 0.1 mm and then sand it, and then soak it in a 3 wt% sodium hydroxide solution for 15 min to obtain pretreated veneer; Immerse the pretreated veneer in the above impregnating solution containing melamine formaldehyde resin, with an impregnation amount of 100%, and then place it in an oven and dry it at 90 °C to obtain the high-efficiency antibacterial decorative veneer, with a volatile content of 9% and a pre-curing degree of 39%.

[0041] Example 3

[0042] A high-efficiency antibacterial decorative veneer, the preparation method thereof includes:

[0043] (1) Impregnating solution containing melamine formaldehyde resin

[0044] Add an aqueous formaldehyde solution with a concentration of 37 wt% to the reaction kettle according to the feed ratio of formaldehyde to melamine of 2.0:1 mol / mol, start the stirrer, add a 30 wt% sodium hydroxide solution to adjust the pH value to 9.0 under stirring conditions, then add 100 parts by weight of melamine and 19 parts by weight of the modifier, heat up to 95 °C within 45 min, keep the temperature for reaction for 40 min, cool down to 60 °C and then add 3 parts by weight of sodium tetraborate, keep the temperature for reaction for 15 min, add a 30 wt% sodium hydroxide solution to adjust the pH value to 8.0, and discharge the material after cooling down to 40 °C to obtain the melamine formaldehyde resin, and control its solid content to be 51 wt%;

[0045] Among them, the modifier is a composite material of chitosan quaternary ammonium salt loaded with nano-TiO₂, which is prepared by the following method: Dissolve 1 part by weight of chitosan (deacetylation degree ≥ 80%) in an acetic acid aqueous solution (0.5 mol / L), adjust the pH value to 6.0 with a 5 wt% sodium hydroxide solution, add an anhydrous ethanol solution containing 30 parts by weight of tetrabutyl titanate, stir and react at room temperature for 6 h, centrifuge to separate the powder, and dry to remove water at 100 °C to obtain the composite material of chitosan quaternary ammonium salt loaded with nano-TiO₂, which is the modifier;

[0046] Here, the chitosan quaternary ammonium salt is prepared by reacting chitosan and 2,3-epoxypropyltrimethylammonium chloride in a weight ratio of 1:2. Specifically, chitosan and 2,3-epoxypropyltrimethylammonium chloride are added to deionized water and stirred and reacted at 70 °C to obtain;

[0047] Add 1 part by weight of triethanolamine to 100 parts by weight of the above melamine formaldehyde resin, stir and mix evenly to obtain an impregnating solution containing melamine formaldehyde resin;

[0048] (2) High-efficiency antibacterial decorative veneer

[0049] Slice poplar into 0.1 mm thick, then sand it, and soak it in a 3 wt% sodium hydroxide solution for 10 min to obtain the pretreated veneer; Immerse the pretreated veneer in the above impregnating solution containing melamine formaldehyde resin, with an impregnation amount of 120%, and then place it in an oven and dry it at 120 °C to obtain the high-efficiency antibacterial decorative veneer, with a volatile content of 8% and a pre-curing degree of 42%.

[0050] Comparative Example 1

[0051] A decorative veneer, the preparation method of which includes:

[0052] (1) An impregnating solution containing melamine formaldehyde resin

[0053] Add an aqueous solution of 37 wt% formaldehyde to the reaction kettle according to the feed ratio of formaldehyde to melamine of 1.9:1 mol / mol, start the stirrer, add a 30 wt% sodium hydroxide solution under stirring conditions to adjust the pH value to 9.5, then add 100 parts by weight of melamine, heat up to 90 °C within 40 min, keep the temperature for reaction for 30 min, add a 30 wt% sodium hydroxide solution to adjust the pH value to 8.0, cool down to 40 °C and then discharge to obtain the melamine formaldehyde resin, and control its solid content to be 54 wt%;

[0054] Add 0.5 part by weight of triethanolamine to 100 parts by weight of the above melamine formaldehyde resin, stir and mix evenly to obtain an impregnating solution containing melamine formaldehyde resin;

[0055] (2) Decorative veneer

[0056] Poplar was rotary cut into 0.1 mm thickness, then sanded, and soaked in 3 wt% sodium hydroxide solution for 10 min to obtain pretreated veneer; the pretreated veneer was immersed in the above-mentioned impregnating solution containing melamine formaldehyde resin with an impregnation amount of 113%, and then placed in an oven and dried at 110 °C to obtain the decorative veneer with a volatile content of 11% and a pre-curing degree of 36%.

[0057] Comparative Example 2

[0058] A decorative veneer, the preparation method thereof comprising:

[0059] (1) An impregnating solution containing melamine formaldehyde resin

[0060] An aqueous solution of formaldehyde with a concentration of 37 wt% was added to a reaction kettle according to a feed ratio of formaldehyde to melamine of 1.9:1 mol / mol, the stirrer was started, and a sodium hydroxide solution with a concentration of 30 wt% was added under stirring conditions to adjust the pH value to 9.5. Then 100 parts by weight of melamine and 3 parts by weight of modifier were added, the temperature was raised to 90 °C within 40 min, and the reaction was carried out at a constant temperature for 30 min. After cooling to 65 °C, 2 parts by weight of sodium tetraborate were added, and the reaction was carried out at a constant temperature for 15 min. A sodium hydroxide solution with a concentration of 30 wt% was added to adjust the pH value to 8.0, and after cooling to 40 °C, the material was discharged to obtain the melamine formaldehyde resin with a solid content controlled at 54 wt%;

[0061] Wherein, the modifier is chitosan quaternary ammonium salt, and the chitosan quaternary ammonium salt is prepared by reacting chitosan and 2,3-epoxypropyltrimethylammonium chloride with a weight ratio of 1:2. Specifically, chitosan and 2,3-epoxypropyltrimethylammonium chloride were added to deionized water and stirred at 70 °C to react;

[0062] 0.5 part by weight of triethanolamine was added to 100 parts by weight of the above-mentioned melamine formaldehyde resin and stirred evenly to obtain the impregnating solution containing melamine formaldehyde resin;

[0063] (2) Decorative veneer

[0064] Poplar was rotary cut into 0.1 mm thickness, then sanded, and soaked in 3 wt% sodium hydroxide solution for 10 min to obtain pretreated veneer; the pretreated veneer was immersed in the above-mentioned impregnating solution containing melamine formaldehyde resin with an impregnation amount of 113%, and then placed in an oven and dried at 110 °C to obtain the decorative veneer with a volatile content of 11% and a pre-curing degree of 36%.

[0065] The antibacterial performance of the above decorative veneer was tested, and the results are shown in Table 1 for reference:

[0066] Table 1 Antibacterial performance test results of decorative veneers in the examples and comparative examples

[0067] Antibacterial types (antibacterial rate) Staphylococcus aureus Escherichia coli Detection standard Example 1 99％ 99％ LY / T1926-2010 Example 2 99％ 99％ LY / T1926-2010 Example 3 99％ 99％ LY / T1926-2010 Comparative example 1 67％ 64％ LY / T1926-2010 Comparative example 2 92％ 88％ LY / T1926-2010

[0068] The above decorative veneers were tested for mildew resistance, and the results are shown in Table 2 for reference:

[0069] Antibacterial types (antibacterial rate) Mildew proof grade Detection standard Example 1 0 LY / T1926-2010 Example 2 0 LY / T1926-2010 Example 3 0 LY / T1926-2010 Comparative example 1 3 LY / T1926-2010 Comparative example 2 2 LY / T1926-2010

[0070] As can be seen from the above table, the decorative veneer of the present invention has both strong antibacterial and antifungal effects.

[0071] The above is only the preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A preparation method of an efficient antibacterial decorative veneer, characterized in that, Comprising: After impregnating veneer with an impregnating solution containing melamine formaldehyde resin and then drying, the antibacterial decorative veneer is obtained; Wherein, the melamine formaldehyde resin is obtained by carrying out a polycondensation reaction on raw materials including formaldehyde, melamine and a modifier, and the modifier is a composite material of chitosan quaternary ammonium salt loaded with nano-TiO2; The composite material of chitosan quaternary ammonium salt loaded with nano-TiO2 is prepared by the following method: Adding an ethanol dispersion of tetrabutyl titanate into an aqueous solution of chitosan quaternary ammonium salt, stirring and reacting, filtering, and drying to remove water, thus obtaining the composite material of chitosan quaternary ammonium salt loaded with nano-TiO2; The weight ratio of tetrabutyl titanate to chitosan quaternary ammonium salt is 15 - 30:1; The melamine formaldehyde resin is prepared by the following method: Adjusting an aqueous solution of formaldehyde to a pH value of 9.0 - 9.5 with a sodium hydroxide solution, adding melamine and a modifier, heating to 85 - 95°C within 35 - 45 min, holding for reaction for 30 - 40 min, then cooling to 60 - 70°C, adding sodium tetraborate, holding for reaction for 10 - 15 min, and then adjusting the pH value to 8.0 - 8.5 with a sodium hydroxide solution, and discharging after cooling to no more than 40°C, thus obtaining the melamine formaldehyde resin; The molar ratio of formaldehyde to melamine is 1.8 - 2.0:1, the dosage of the modifier is 12 - 19 wt% of melamine, and the dosage of sodium tetraborate is 1 - 3 wt% of melamine.

2. The preparation method of the high-efficiency antibacterial decorative veneer according to claim 1, characterized in that, The solid content of the melamine formaldehyde resin is 51 - 58 wt%.

3. The preparation method of the highly efficient antibacterial decorative veneer according to claim 1 or 2, characterized in that, The impregnating solution further includes a curing agent.

4. The preparation method of the highly efficient antibacterial decorative veneer according to claim 3, characterized in that, The curing agent is triethanolamine and / or hexamethylenetetramine, and its dosage is 0.3 - 1 wt% of the melamine formaldehyde resin.

5. The preparation method of the highly efficient antibacterial decorative veneer according to claim 1 or 2, characterized in that, After impregnating veneer with an impregnating solution containing melamine formaldehyde resin and then drying, the impregnation amount of the veneer is 100 - 120%, and the drying temperature is 90 - 120°C, and the time is 60 - 120 s.

6. The preparation method of the highly efficient antibacterial decorative veneer according to claim 1 or 2, characterized in that Before impregnating veneer with an impregnating solution containing melamine formaldehyde resin, it further includes pretreating the veneer.

7. The preparation method of the highly efficient antibacterial decorative veneer according to claim 6, characterized in that The pretreatment includes: after sanding the veneer, soaking it in a weakly alkaline solution for 10 - 15 min.

8. An efficient antibacterial decorative veneer, characterized in that, It is prepared by the preparation method according to any one of claims 1 - 7.