Preparation method of antibacterial alkyd resin coating

Abstract

The invention belongs to the technical field of resin coating preparation, and particularly relates to a preparation method of an antibacterial alkyd resin coating. Comprising the following steps: alcoholysis reaction: putting soybean oil, glycerol, phthalic anhydride, butyl acetate and deionized water into a reaction kettle according to a ratio, adding a catalyst, and heating to react until the alcoholysis end point is reached; esterification reaction: reducing the reaction temperature, and adding phthalic anhydride and a reflux solvent xylene; raising the temperature to carry out condensation polymerization until an esterification end point is reached; diluting and filtering: adding a prepared solvent into the reaction kettle for diluting, adjusting the viscosity, filtering and discharging for later use; the prepared nano-silver solution is slowly added into resin, then 0.5%-1% of a silane coupling agent is added, and mechanical stirring is conducted; transferring the prepared pigment grinding slurry to a paint mixing tank, and adjusting to construction viscosity by using a solvent; compared with an additive antibacterial agent, the antibacterial resin coating prepared by the invention has more stable and lasting antibacterial time and can achieve the same antibacterial effect.

Description

Technical Field

[0001] This invention relates to the field of resin coating preparation technology, and in particular to a method for preparing an antibacterial alkyd resin coating. Background Technology

[0002] Alkyd resins are polyesters made from polyols, polyacids, and fatty acids, unlike polyester resins made solely from polyols and polyacids. Alkyd resin molecules contain residual hydroxyl and carboxyl groups, resulting in coatings with better adhesion than oil-based paints. They are characterized by good synthesis technology, simple manufacturing processes, and excellent overall performance of the resin coating, making them widely used in the coatings industry. They can be formulated into varnishes, colored paints, industrial-grade paints, and general-purpose paints.

[0003] Currently, many antibacterial coatings are additive-based, produced by adding antibacterial agents with antibacterial functions and processing them through specific techniques. In contrast, structural antibacterial coatings connect antibacterial groups to polymer molecular chains through chemical bonds, using this polymer as a base material to formulate the antibacterial coating. The development of structural antibacterial coatings is still in its early stages. Compared with additive-based antibacterial coatings, structural antibacterial coatings have advantages such as durability and stability, but their antibacterial effect still needs to be improved compared to additive-based antibacterial agents. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method for preparing antibacterial alkyd resin coatings, overcoming the problem of insufficient antibacterial effect in existing structural antibacterial coatings.

[0005] To achieve the above-mentioned technical objectives, the specific technical solution of the present invention is as follows: The preparation method of an antibacterial alkyd resin coating proposed in the present invention includes the following preparation steps:

[0006] Step 1, alcoholysis reaction: Add soybean oil, glycerol, phthalic anhydride, butyl acetate and deionized water into the reaction vessel in proportion, add catalyst; heat to 220-240℃ and keep at that temperature for 0.5-1 hour; take samples for testing until the alcoholysis endpoint is reached;

[0007] Step 2, Esterification reaction: Lower the reaction temperature to 190-210℃, add phthalic anhydride and reflux solvent xylene; reheat to 230-240℃ to carry out polycondensation reaction, separate the water produced by the esterification reaction through a water separator, and react until the acid value is ≤12mg KOH / g; take samples for testing until the esterification endpoint is reached;

[0008] Step 3, dilution and filtration: Reduce the reaction temperature to 150-160℃, add the pre-prepared solvent (a mixture of 200# solvent oil and xylene) to dilute, adjust the viscosity, stir vigorously to dissolve evenly, and continue to cool to below 65℃ to obtain the basic alkyd resin solution. Filter and discharge for later use.

[0009] Step 4, Ingredient Preparation and Mixing: In a mixing tank, add a portion of the base alkyd resin, dispersant, and defoamer, and disperse and mix at high speed until uniform. Then, heat to 50-60℃ and add a small amount of solvent to adjust to a suitable viscosity for coating. Slowly add the prepared nano-silver solution to the resin, then add 0.5%-1% of silane coupling agent and mechanically stir to improve the compatibility between the resin and nano-silver and ensure uniform dispersion. Then, disperse and wet at high speed to prepare a pre-dispersed paint slurry.

[0010] Step 5, Paint Mixing: Transfer the prepared pigment grinding paste to the paint mixing tank, add the reserved resin, drier, and anti-skinning agent, and stir evenly; adjust to the working viscosity with solvent, and mature at low speed for 8-24 hours to ensure that the components are fully compatible and that air bubbles escape.

[0011] Step 6, Filtration and Packaging: Filter the coating using a filter screen or filtration equipment to remove impurities and particles, obtaining an antibacterial alkyd resin coating. Pack the coating after filtration.

[0012] As a preferred embodiment of the present invention, nitrogen gas is introduced during the alcoholysis reaction in step one for protection to prevent resin oxidation and darkening of color.

[0013] As a preferred technical solution of the present invention, the sampling and detection method in step one is as follows: after the reaction has been carried out for 0.5 hours, sampling and detection are performed every 10 minutes. When the compatibility of the sample with methanol reaches 1:3-5 and the sample is clear, the alcoholysis endpoint is reached.

[0014] As a preferred technical solution of the present invention, the sampling and detection method in step two is as follows: sampling and detection are performed every 10 minutes to determine the acid value and viscosity. When the acid value drops below 10 mg KOH / g and the viscosity reaches 25°C, the viscosity value is measured using a Gastrin tube. If the viscosity falls within the range of 3-6 seconds, it is the esterification endpoint.

[0015] As a preferred technical solution of the present invention, the method for preparing the nano-silver solution in step four is as follows: mix the nano-silver sol and the solvent in a ratio of 1:5, add 0.1%-0.5% of dispersant (such as PVP); sonicate (frequency 40kHz, power 300W) for 20-30 minutes until the solution is uniformly light yellow and transparent, with no visible agglomerates.

[0016] As a preferred technical solution of the present invention, the preparation method of pigment grinding in step five is as follows: a specified proportion of pigment, dispersant and solvent are added to the grinding tank, and the paint slurry is ground to a fineness of ≤20μm using a sand mill to wet and disperse the pigment and obtain a grinding slurry of a specified color.

[0017] As a preferred embodiment of the present invention, in step four, after adding the prepared nano-silver solution, 0.5%-1% of a silane coupling agent is added, and KH-550 is used as the silane coupling agent. The mixture is mechanically stirred at a speed of 500-1000 rpm / min for 30 minutes.

[0018] As a preferred embodiment of the present invention, in step six, a 200-mesh filter screen is used to filter the coating.

[0019] The beneficial effects of this invention are as follows: This invention treats nano-silver with a silane coupling agent (such as KH-550) to generate hydroxyl or amino groups on its surface, which then react with functional groups (such as carboxyl or epoxy groups) in the resin to form chemical bonds that combine the nano-silver solution with the alkyd resin system, giving the coating broad-spectrum antibacterial properties. Compared with additive antibacterial agents, the resin coating prepared by this invention has a more stable and longer-lasting antibacterial duration and can achieve the same antibacterial effect. Detailed Implementation

[0020] 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.

[0021] This embodiment discloses a method for preparing an antibacterial alkyd resin coating, including the following preparation steps:

[0022] Step 1, alcoholysis reaction: Soybean oil, glycerol, phthalic anhydride, butyl acetate and deionized water are added to the reactor in proportion, and a catalyst (such as LiOH) is added; nitrogen gas is introduced for protection to prevent resin oxidation and darkening of color, the temperature is raised to 220-240℃ and held for 0.5-1 hour, and after reacting for 0.5 hours, samples are taken every 10 minutes to test its compatibility with methanol (usually requiring a clear 1:3-5 ratio) until the alcoholysis endpoint is reached;

[0023] Step 2, Esterification Reaction: Lower the reaction temperature to 190-210℃, add phthalic anhydride and reflux solvent xylene (6%); reheat to 230-240℃ for polycondensation reaction, separate the water produced by the esterification reaction using a water separator, and react until the acid value is ≤12mg KOH / g; take samples every 10 minutes to test the acid value and viscosity. When the acid value drops below 10mg KOH / g and the viscosity reaches the specified range (e.g., Gastrin tube, 25℃, 3-6 seconds), the esterification endpoint is reached.

[0024] Step 3, dilution and filtration: Reduce the reaction temperature to 150-160℃, add the pre-prepared solvent (a mixture of 200# solvent oil and xylene) to dilute, adjust the viscosity, stir vigorously to dissolve evenly, and continue to cool to below 65℃ to obtain the basic alkyd resin solution. Filter and discharge for later use.

[0025] Step 4, Ingredient Preparation and Mixing: In a mixing tank, add a portion of the base alkyd resin, dispersant, and defoamer. Disperse and mix at high speed until homogeneous. Then heat to 50-60℃ to reduce viscosity and facilitate mixing. Add a small amount of solvent to adjust to a suitable viscosity for coating (e.g., Ford cup 4, 20-30 seconds). Slowly add the prepared nano-silver solution to the resin, then add 0.5%-1% of a silane coupling agent (e.g., KH-550). Mechanically stir (500-1000 rpm) for 30 minutes. The silane coupling agent can generate hydroxyl or amino groups on the surface of the nano-silver solution, which then react with functional groups (e.g., carboxyl groups, epoxy groups) in the resin to form chemical bonds, improving the compatibility between the resin and nano-silver and ensuring uniform dispersion. Then disperse and wet at high speed to prepare a pre-dispersed paint slurry.

[0026] The method for preparing the nano-silver solution is as follows: mix the nano-silver sol with a solvent (ethanol or water) in a ratio of 1:5, add 0.1%-0.5% of a dispersant (such as PVP); sonicate (frequency 40kHz, power 300W) for 20-30 minutes until the solution is a uniform light yellow transparent state with no visible agglomerates;

[0027] Step 5, Paint Mixing: Add the specified proportions of pigment, dispersant, and solvent to the grinding tank, and grind the paint slurry to a fineness of ≤20μm using a sand mill to wet and disperse the pigment, obtaining a grinding slurry of the specified color; transfer the prepared pigment grinding slurry to the paint mixing tank, add the reserved resin, drier, and anti-skinning agent, and stir evenly; adjust to the application viscosity with solvent, and mature at low speed for 8-24 hours to ensure that the components are fully compatible and that air bubbles escape.

[0028] Step 6, Filtration and Packaging: Filter the coating using a filter screen or filtration equipment to remove impurities and particles, obtaining an antibacterial alkyd resin coating. Pack the coating after filtration.

[0029] Example 1:

[0030] Step 1, alcoholysis reaction: Take 120g soybean oil acid, 110g glycerol, 60g phthalic anhydride, 150g butyl acetate and 450g deionized water and add them to the reaction vessel. Add 5g LiOH to carry out the catalytic reaction. Nitrogen gas is introduced for protection during the reaction. The temperature is raised to 220℃ and the reaction is carried out for 1 hour. The alcoholysis endpoint is detected.

[0031] Step 2, Esterification reaction: Lower the reaction temperature to 200℃, add 30g of phthalic anhydride and 150g of 200# reflux solvent xylene; reheat to 220℃ to carry out polycondensation reaction, separate the water produced by the esterification reaction through a water separator, and react until the acid value is ≤12mgKOH / g; take a sample after 40min of reaction to detect that the esterification endpoint has been reached;

[0032] Step 3, dilution and filtration: Reduce the reaction temperature to 150℃, add 40g of pre-prepared solvent (a 1:1 mixture of 200# solvent oil and xylene) to dilute, adjust the viscosity, stir vigorously to dissolve evenly, continue to cool to 60℃ to obtain the basic alkyd resin solution, filter and discharge for later use.

[0033] Step 4, Ingredients and Mixing: In the mixing tank, add 50g of base alkyd resin, 1.2g of dispersant and 1g of defoamer, disperse and mix evenly at high speed, then heat to 60℃, add 5g of xylene solvent to adjust to a suitable viscosity for coating;

[0034] Preparation of nano-silver: 12g of nano-silver sol was mixed with 60g of ethanol, and 0.2g of PVP dispersant was added. The mixture was then treated in an ultrasonic cleaner (40kHz, 300W) for 25 minutes to obtain a uniform light yellow transparent solution.

[0035] Then, the prepared nano-silver solution was slowly added to the resin, followed by the addition of 1g KH-550. The mixture was mechanically stirred at 80rpm for 30 minutes to prepare a pre-dispersed paint slurry.

[0036] Step 5, Paint Mixing: Add 30g titanium dioxide, 1.2g dispersant and 1g xylene solvent to the grinding tank, and grind the paint slurry to a fineness of ≤20μm using a sand mill to obtain a grinding slurry; transfer the prepared grinding slurry to the paint mixing tank, add the reserved resin, drier and anti-skinning agent, and stir evenly; adjust to the application viscosity with xylene solvent, and mature for 12 hours under low speed stirring;

[0037] Step 6, Filtration and Packaging: Use a 200-mesh filter to remove impurities and particles to obtain an antibacterial alkyd resin coating.

[0038] Example 2:

[0039] Step 1, alcoholysis reaction: Take 120g soybean oil acid, 110g glycerol, 60g phthalic anhydride, 150g butyl acetate and 450g deionized water and add them to the reaction vessel. Add 5g LiOH to carry out the catalytic reaction. Nitrogen gas is introduced for protection during the reaction. The temperature is raised to 220℃ and the reaction is carried out for 1 hour. The alcoholysis endpoint is detected.

[0040] Step 2, Esterification reaction: Lower the reaction temperature to 200℃, add 30g of phthalic anhydride and 150g of 200# reflux solvent xylene; reheat to 220℃ to carry out polycondensation reaction, separate the water produced by the esterification reaction through a water separator, and react until the acid value is ≤12mgKOH / g; take a sample after 40min of reaction to detect that the esterification endpoint has been reached;

[0041] Step 3, dilution and filtration: Reduce the reaction temperature to 150℃, add 40g of pre-prepared solvent (a 1:1 mixture of 200# solvent oil and xylene) to dilute, adjust the viscosity, stir vigorously to dissolve evenly, continue to cool to 60℃ to obtain the basic alkyd resin solution, filter and discharge for later use.

[0042] Step 4, Ingredients and Mixing: In the mixing tank, add 50g of base alkyd resin, 1.2g of dispersant and 1g of defoamer, disperse and mix evenly at high speed, then heat to 60℃, add 5g of xylene solvent to adjust to a suitable viscosity for coating;

[0043] Preparation of nano-silver: Mix 10g of nano-silver sol with 50g of ethanol, add 0.2g of PVP dispersant, and treat in an ultrasonic cleaner (40kHz, 300W) for 25 minutes to obtain a uniform light yellow transparent solution.

[0044] Then, the prepared nano-silver solution was slowly added to the resin, followed by the addition of 1g KH-550. The mixture was mechanically stirred at 80rpm for 30 minutes to prepare a pre-dispersed paint slurry.

[0045] Step 5, Paint Mixing: Add 30g titanium dioxide, 1.2g dispersant and 1g xylene solvent to the grinding tank, and grind the paint slurry to a fineness of ≤20μm using a sand mill to obtain a grinding slurry; transfer the prepared grinding slurry to the paint mixing tank, add the reserved resin, drier and anti-skinning agent, and stir evenly; adjust to the application viscosity with xylene solvent, and mature for 12 hours under low speed stirring;

[0046] Step 6, Filtration and Packaging: Use a 200-mesh filter to remove impurities and particles to obtain an antibacterial alkyd resin coating.

[0047] Example 3:

[0048] Step 1, alcoholysis reaction: Take 120g soybean oil acid, 110g glycerol, 60g phthalic anhydride, 150g butyl acetate and 450g deionized water and add them to the reaction vessel. Add 5g LiOH to carry out the catalytic reaction. Nitrogen gas is introduced for protection during the reaction. The temperature is raised to 220℃ and the reaction is carried out for 1 hour. The alcoholysis endpoint is detected.

[0049] Step 2, Esterification reaction: Lower the reaction temperature to 200℃, add 30g of phthalic anhydride and 150g of 200# reflux solvent xylene; reheat to 220℃ to carry out polycondensation reaction, separate the water produced by the esterification reaction through a water separator, and react until the acid value is ≤12mgKOH / g; take a sample after 40min of reaction to detect that the esterification endpoint has been reached;

[0050] Step 3, dilution and filtration: Reduce the reaction temperature to 150℃, add 40g of pre-prepared solvent (a 1:1 mixture of 200# solvent oil and xylene) to dilute, adjust the viscosity, stir vigorously to dissolve evenly, continue to cool to 60℃ to obtain the basic alkyd resin solution, filter and discharge for later use.

[0051] Step 4, Ingredients and Mixing: In the mixing tank, add 50g of base alkyd resin, 1.2g of dispersant and 1g of defoamer, disperse and mix evenly at high speed, then heat to 60℃, add 5g of xylene solvent to adjust to a suitable viscosity for coating;

[0052] Preparation of nano-silver: 15g of nano-silver sol was mixed with 75g of ethanol, and 0.2g of PVP dispersant was added. The mixture was then treated in an ultrasonic cleaner (40kHz, 300W) for 25 minutes to obtain a uniform light yellow transparent solution.

[0053] Then, the prepared nano-silver solution was slowly added to the resin, followed by the addition of 1g KH-550. The mixture was mechanically stirred at 80rpm for 30 minutes to prepare a pre-dispersed paint slurry.

[0054] Step 5, Paint Mixing: Add 30g titanium dioxide, 1.2g dispersant and 1g xylene solvent to the grinding tank, and grind the paint slurry to a fineness of ≤20μm using a sand mill to obtain a grinding slurry; transfer the prepared grinding slurry to the paint mixing tank, add the reserved resin, drier and anti-skinning agent, and stir evenly; adjust to the application viscosity with xylene solvent, and mature for 12 hours under low speed stirring;

[0055] Step 6, Filtration and Packaging: Use a 200-mesh filter to remove impurities and particles to obtain an antibacterial alkyd resin coating.

[0056] The antibacterial alkyd resin coatings prepared in Examples 1, 2, and 3 were subjected to antibacterial tests. The tested bacteria included three species: Staphylococcus aureus, Escherichia coli, and Aspergillus niger. The test results are shown in Table 1 below.

[0057] Q = (X1 - X2) / X1 × 100%, where Q is the antibacterial rate, X1 is the average number of recovered bacteria in the blank control sample, and X2 is the average number of recovered bacteria in the coating sample.

[0058] The comparative example differs from Examples 1, 2, and 3 in that the prepared nano-silver solution was not slowly added to the resin in step 4.

[0059] Table 1

[0060] Components Staphylococcus aureus antibacterial rate % E. coli antibacterial rate % Aspergillus niger antibacterial rate % Example 1 98.1 98.3 98.6 Example 2 97.9 98.2 98.3 Example 3 98.4 98.7 98.8 Comparative Example 40.2 38.9 41.3

[0061] As shown in the table above, the antibacterial alkyd resin coating prepared by the above preparation method of the present invention has a significantly higher antibacterial rate against various bacterial species than the comparative example. Moreover, the antibacterial effect of additive antibacterial agents in the prior art is in the range of 95%-99.9%. The present invention treats nano-silver with a silane coupling agent (such as KH-550) to generate hydroxyl or amino groups on its surface, which then react with functional groups (such as carboxyl groups and epoxy groups) in the resin to form chemical bonds that combine the nano-silver solution with the alkyd resin system. The prepared resin coating has a more stable and longer antibacterial duration and can achieve the same antibacterial effect.

[0062] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an antibacterial alkyd resin coating, characterized in that, The preparation steps include the following: Step 1, alcoholysis reaction: Add soybean oil, glycerol, phthalic anhydride, butyl acetate and deionized water into the reaction vessel in proportion, add catalyst; heat to 220-240℃ and keep at that temperature for 0.5-1 hour; take samples for testing until the alcoholysis endpoint is reached; Step 2, Esterification reaction: Lower the reaction temperature to 190-210℃, add phthalic anhydride and reflux solvent xylene; reheat to 230-240℃ to carry out polycondensation reaction, separate the water produced by the esterification reaction through a water separator, and react until the acid value is ≤12mg KOH / g; take samples for testing until the esterification endpoint is reached; Step 3, dilution and filtration: Reduce the reaction temperature to 150-160℃, add the pre-prepared solvent to dilute, adjust the viscosity, stir vigorously to make it evenly dissolved, continue to cool to below 65℃ to obtain the basic alkyd resin solution, filter and discharge for later use. Step 4, Ingredient Preparation and Mixing: In the mixing tank, add some basic alkyd resin, dispersant, and defoamer, disperse and mix evenly at high speed, then heat to 50-60℃, add a small amount of solvent to adjust to a suitable coating viscosity; slowly add the prepared nano-silver solution to the resin, then add 0.5%-1% silane coupling agent, mechanically stir to improve the compatibility between the resin and nano-silver, and ensure uniform dispersion; Then, high-speed dispersion and wetting were performed to prepare a pre-dispersed paint slurry; Step 5, Paint Mixing: Transfer the prepared pigment grinding paste to the paint mixing tank, add the reserved resin, drier, and anti-skinning agent, and stir evenly; adjust to the working viscosity with solvent, and mature at low speed for 8-24 hours to ensure that the components are fully compatible and that air bubbles escape. Step 6, Filtration and Packaging: Filter the coating using a filter screen or filtration equipment to remove impurities and particles, obtaining an antibacterial alkyd resin coating. Pack the coating after filtration.

2. The method for preparing an antibacterial alkyd resin coating according to claim 1, characterized in that, In step one, nitrogen gas needs to be introduced during the alcoholysis reaction to protect the resin from oxidation and darkening of color.

3. The method for preparing an antibacterial alkyd resin coating according to claim 1, characterized in that, The sampling and testing method in step one is as follows: after reacting for 0.5 hours, samples are taken and tested every 10 minutes. When the compatibility with methanol reaches 1:3-5 and the sample is clear, the alcoholysis endpoint is reached.

4. The method for preparing an antibacterial alkyd resin coating according to claim 1, characterized in that, The sampling and testing method in step two is as follows: sampling and testing are carried out every 10 minutes to determine the acid value and viscosity. When the acid value drops below 10 mg KOH / g and the viscosity reaches the range of 3-6 seconds when measured by a Gastrin tube at 25°C, the esterification endpoint is reached.

5. The method for preparing an antibacterial alkyd resin coating according to claim 1, characterized in that, The method for preparing the nano-silver solution in step four is as follows: mix the nano-silver sol and solvent in a ratio of 1:5, add 0.1%-0.5% dispersant; sonicate for 20-30 minutes until the solution is a uniform light yellow transparent state with no visible agglomerates.

6. The method for preparing an antibacterial alkyd resin coating according to claim 1, characterized in that, The preparation method for pigment grinding in step five is as follows: a specified proportion of pigment, dispersant and solvent are added to the grinding tank, and the paint slurry is ground to a fineness of ≤20μm using a sand mill to wet and disperse the pigment, thereby obtaining a grinding slurry of the specified color.

7. The method for preparing an antibacterial alkyd resin coating according to claim 1, characterized in that, In step four, after adding the prepared nano-silver solution, 0.5%–1% of silane coupling agent is added. The silane coupling agent used is KH-550. The mixture is mechanically stirred at a speed of 500–1000 rpm / min for 30 minutes.

8. A method for preparing an antibacterial alkyd resin coating according to claim 1 or 7, characterized in that, In step six, a 200-mesh filter is used to filter the coating.