Long-acting mildew-proof coating and preparation method thereof

Abstract

The present application relates to the technical fields of high polymer material and functional coating, and discloses a long-acting mildew-proof coating and a preparation method thereof.The coating comprises an A component and a B component, wherein the A component is a polyisocyanate curing agent; the base resin of the B component is prepared by radiation copolymerization of a double bond functionalized isothiazolinone derivative and an acrylate monomer, and the resin has the advantages of narrow molecular weight distribution, no initiator residue, light color, uniform hydroxyl distribution and the like.The polyurethane coating prepared by using the resin has a dense and uniform crosslinked network after curing, and the above-mentioned mildew-proof monomer is directly bonded to the polymer molecular chain through a chemical bond, so that the material has long-acting and stable mildew-proof performance, and the obtained coating film has excellent mechanical properties, chemical resistance and durability.

Description

Technical Field

[0001] This invention relates to the field of polymer materials and functional coatings, specifically to a method for preparing a long-lasting anti-mildew coating. Background Technology

[0002] Two-component polyurethane coatings are widely used in automobiles, furniture, construction, medical devices and other fields due to their excellent mechanical properties, chemical resistance and decorative properties. Component A is a polyisocyanate curing agent and component B is a hydroxyl-containing resin, including hydroxyl acrylic resin and hydroxyl polyester resin. Traditional hydroxyl acrylic resins are mostly prepared by thermally initiated free radical polymerization. This process has problems such as initiator residue, high reaction temperature which easily produces side reactions, and difficulty in accurately controlling the molecular weight and functional group distribution, which restricts the further improvement of the final coating performance.

[0003] On the other hand, endowing coating surfaces with antibacterial and antifungal functions has become a key technology for enhancing product added value and meeting the needs of specific fields such as medical and health care and public facilities. Existing technologies often physically blend small molecule quaternary ammonium salt antibacterial agents into coatings. However, such antibacterial agents are prone to migration and dissolution, resulting in a short antibacterial effective period and potentially causing environmental and health risks, such as microbial resistance and pollution. Although some studies have introduced polymerizable vinyl-containing quaternary ammonium salt monomers into resin chains through chemical copolymerization, the polymerization conditions of such monomers are prone to mismatch with the activity of functional monomers, and the antibacterial groups are deeply buried inside the paint film with insufficient effective surface concentration, affecting the antibacterial efficiency.

[0004] Currently, there are two main technical approaches related to this invention:

[0005] 1. Polyurethane coatings with physically blended antibacterial agents: Traditional small-molecule antibacterial agents are directly added to the coating components. As mentioned above, the disadvantages are that the antibacterial agent / mildew inhibitor is bonded to the substrate by non-covalent bonds, making it easy to migrate and be lost, resulting in short-lasting antibacterial effects, and potentially affecting the transparency, color, and physical properties of the coating film.

[0006] 2. Preparation of copolymeric antibacterial resin: In the synthesis of hydroxyl acrylic resin, vinyl-containing quaternary ammonium salt antibacterial monomers (such as methacryloyloxyethyltrimethylammonium chloride) are thermally initiated copolymerized with other acrylic monomers. Although this method can chemically bond antibacterial groups to the resin chain, it still has limitations: (1) The high temperature of the thermally initiated polymerization process may affect the structural stability of some quaternary ammonium salt monomers; (2) The polymerization process and initiator residues may affect the color and weather resistance of the resin; (3) The distribution of antibacterial monomers in the copolymer chain is difficult to control precisely.

[0007] 3. Applications of irradiation polymerization in polymer synthesis: electron beam (EB) or cobalt source ( 60Radiation polymerization (C) is a green and efficient polymerization technology that has been used to synthesize acrylate resins. It offers advantages such as low temperature, rapid polymerization, no initiator residue, and narrow molecular weight distribution. However, current technologies mainly focus on using radiation polymerization to prepare general-purpose resins and have not yet been systematically applied to the synthesis of high-performance hydroxyl acrylic resin components specifically for two-component PU coatings. Summary of the Invention

[0008] The purpose of this invention is to provide a long-lasting anti-mildew coating and its preparation method to solve the problems mentioned in the background art: how to obtain a high-quality hydroxyl acrylic resin with a purer structure, more precise molecular design, and superior performance as a base polymer for polyurethane coatings to improve the overall performance, durability, and anti-mildew properties of the coating film; and how to permanently and stably fix the highly effective anti-mildew components in the polyurethane coating film to avoid the migration of the anti-mildew agent and achieve a long-lasting and safe contact-type anti-mildew effect.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a long-lasting anti-mildew coating and its preparation method, wherein the coating comprises component A and component B, wherein:

[0010] Component A is a polyisocyanate curing agent;

[0011] Component B is prepared through the following steps:

[0012] Step 1: Preparation of antifungal functional monomers containing polymerizable double bonds

[0013] Isothiazolinone derivatives and polymerization inhibitor hydroquinone are added to a polar aprotic solvent such as DMF. The mixture is heated to 40-50°C and stirred until completely dissolved. Then, triethylamine is slowly added dropwise while stirring for 20-30 minutes to deprotonate and activate the imino group of the isothiazolinone derivative. The system is then heated to 55-65°C, and excess glycidyl methacrylate is slowly added dropwise. After the addition is complete, the reaction is maintained at this temperature for 4-6 hours until the characteristic peak of epoxy in infrared detection is significantly weakened and the epoxy value titration shows that the reaction is basically complete. After the reaction is completed, the mixture is cooled to room temperature, and a small amount of insoluble matter is removed by filtration to obtain a polymerizable functional monomer containing an isothiazolinone structure.

[0014] Step 2: Radiation preparation of the base resin for anti-mildew coating

[0015] Using alkyl acrylate monomers, hydroxyl-containing acrylate monomers, other functional monomers, and the anti-mildew functional monomers prepared in step one as raw materials, they are dissolved in an appropriate amount of solvent and α-methylstyrene dimer is added as a chain transfer agent to prepare a reaction solution. The reaction solution is placed under an irradiation device for radiation polymerization. After the reaction is completed, the solvent and low molecular weight products are removed by distillation to obtain an anti-mildew hydroxyl acrylic resin with a narrow molecular weight distribution, uniform hydroxyl distribution, and no chemical initiator residue. This resin is the base resin of the subsequent component B.

[0016] Step 3: Preparation of Anti-mildew Coating

[0017] The base resin, stabilizer, pigments and fillers, leveling agent, defoamer and solvent obtained in step two are mixed evenly according to the coating formula to prepare component B coating slurry;

[0018] Step 4: Coating Application and Curing

[0019] The B component, which has undergone step three, is mixed with the A component at a -NCO / -OH equivalent ratio and coated onto the substrate surface. The mixture then undergoes a curing reaction at ambient temperature to form a polyurethane coating with a three-dimensional network structure.

[0020] Preferably, the ratio of component B to component A in the -NCO / -OH equivalent ratio is 1.05-1.15:1.

[0021] Preferably, the polyisocyanate curing agent is one or more of TDI, MDI, HDI or IPDI.

[0022] Preferably, in step two, the alkyl acrylate monomer is methyl methacrylate or butyl acrylate; the hydroxyl-containing acrylate monomer is hydroxyethyl acrylate or hydroxypropyl acrylate; and the other functional monomers are (meth)acrylic acid or styrene.

[0023] Preferably, the isothiazolinone derivative is one or more of methylisothiazolinone, benzisothiazolinone, n-octylisothiazolinone, and chloromethylisothiazolinone.

[0024] Preferably, the antifungal monomer isothiazolinone derivative, after double bond functionalization modification, possesses free radical polymerization activity and can directly copolymerize with acrylate monomers to form polymer chains during subsequent radiation polymerization.

[0025] Preferably, in step two, the irradiation reaction is carried out under an inert atmosphere using... 60 Co-γ ray polymerization involves controlling the irradiation dose, time, and temperature to induce free radical copolymerization of the monomers.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] 1. This invention obtains a high-performance coating base resin, a hydroxyl acrylic resin synthesized by radiation polymerization technology, which has advantages such as narrow molecular weight distribution, no initiator residue, light color, and uniform hydroxyl distribution. Polyurethane coatings based on this resin have a denser and more uniform crosslinking network after curing. The anti-mildew monomer isothiazolinone derivative, after double bond functionalization modification, has free radical polymerization activity and can directly copolymerize with acrylate monomers to form polymer chains in subsequent radiation polymerization, thereby giving the material long-lasting and stable anti-mildew properties. The coating film has better mechanical properties, excellent chemical resistance, and outstanding durability.

[0028] 2. This invention uses radiation polymerization to fix functionalized antifungal agents onto the resin molecular chain via covalent bonds, forming a chemical anchor in the final polyurethane network. This fundamentally avoids the migration and loss problems caused by physical blending. The antifungal lifespan is comparable to that of the coating, with no release of small molecule antifungal agents, making it environmentally friendly and in line with green chemistry and sustainable development requirements. It is particularly suitable for sensitive fields such as medical devices, children's products, and food contact surfaces. This invention adopts a strategy of radiation-initiated free radical polymerization, and the entire process can be carried out at low temperatures, with low energy consumption and no or significantly reduced use of chemical initiators, reducing the generation of VOCs and by-products. It is an environmentally friendly clean production process.

[0029] 3. This invention applies the irradiation polymerization technology to the preparation of a high-performance hydroxyl acrylic resin for two-component polyurethane coatings. Attached Figure Description

[0030] Figure 1 This is a flowchart of the long-lasting anti-mildew coating and its preparation method according to the present invention. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0032] Example:

[0033] Please see Figure 1 A long-lasting anti-mildew coating and its preparation method, wherein the coating comprises component A and component B, wherein:

[0034] Component A is a polyisocyanate curing agent;

[0035] Component B is prepared through the following steps:

[0036] Step 1: Preparation of antifungal functional monomers containing polymerizable double bonds

[0037] Isothiazolinone derivatives and polymerization inhibitor hydroquinone are added to a polar aprotic solvent such as DMF. The mixture is heated to 40-50°C and stirred until completely dissolved. Then, triethylamine is slowly added dropwise while stirring for 20-30 minutes to deprotonate and activate the imino group of the isothiazolinone derivative. The system is then heated to 55-65°C, and excess glycidyl methacrylate is slowly added dropwise. After the addition is complete, the reaction is maintained at this temperature for 4-6 hours until the characteristic peak of epoxy in infrared detection is significantly weakened and the epoxy value titration shows that the reaction is basically complete. After the reaction is completed, the mixture is cooled to room temperature, and a small amount of insoluble matter is removed by filtration to obtain a polymerizable functional monomer containing an isothiazolinone structure.

[0038] Step 2: Radiation preparation of the base resin for anti-mildew coating

[0039] Using alkyl acrylate monomers, hydroxyl-containing acrylate monomers, other functional monomers, and the anti-mildew functional monomers prepared in step one as raw materials, they are dissolved in an appropriate amount of solvent and α-methylstyrene dimer is added as a chain transfer agent to prepare a reaction solution. The reaction solution is placed under an irradiation device for radiation polymerization. After the reaction is completed, the solvent and low molecular weight products are removed by distillation to obtain an anti-mildew hydroxyl acrylic resin with a narrow molecular weight distribution, uniform hydroxyl distribution, and no chemical initiator residue. This resin is the base resin of the subsequent component B.

[0040] Step 3: Preparation of Anti-mildew Coating

[0041] The base resin, stabilizer, pigments and fillers, leveling agent, defoamer and solvent obtained in step two are mixed evenly according to the coating formula to prepare component B coating slurry;

[0042] Step 4: Coating Application and Curing

[0043] The B component, which has undergone step three, is mixed with the A component at a -NCO / -OH equivalent ratio and coated onto the substrate surface. The mixture then undergoes a curing reaction at ambient temperature to form a polyurethane coating with a three-dimensional network structure.

[0044] In this embodiment, the ratio of component B to component A in the -NCO / -OH equivalent ratio is 1.05-1.15:1.

[0045] In this embodiment, the polyisocyanate curing agent is one or more of TDI, MDI, HDI or IPDI.

[0046] In this embodiment: in step two, the alkyl acrylate monomer is methyl methacrylate or butyl acrylate; the hydroxyl-containing acrylate monomer is hydroxyethyl acrylate or hydroxypropyl acrylate; and other functional monomers are (meth)acrylic acid or styrene.

[0047] In this embodiment, the isothiazolinone derivative is one or more of methylisothiazolinone, benzisothiazolinone, n-octylisothiazolinone, and chloromethylisothiazolinone.

[0048] In this embodiment, the antifungal monomer isothiazolinone derivative, after being modified by double bond functionalization, possesses free radical polymerization activity and can be directly copolymerized with acrylate monomers to form polymer chains during subsequent radiation polymerization.

[0049] In this embodiment: In step two, the irradiation reaction is carried out under an inert atmosphere using... 60 Co-γ ray polymerization involves controlling the irradiation dose, time, and temperature to induce free radical copolymerization of the monomers.

[0050] In summary, this invention obtains a high-performance coating base resin, specifically a hydroxyl acrylic resin synthesized using radiation polymerization technology. This resin possesses advantages such as narrow molecular weight distribution, no initiator residue, light color, and uniform hydroxyl distribution. Polyurethane coatings based on this resin exhibit a denser and more uniform cross-linked network after curing. The isothiazolinone derivative, a fungicide monomer, undergoes double-bond functionalization modification, possessing free radical polymerization reactivity. It can directly copolymerize with acrylate monomers to form polymer chains during subsequent radiation polymerization, thereby endowing the material with long-lasting and stable fungicide resistance. The coating film exhibits superior mechanical properties, excellent chemical resistance, and outstanding durability, fundamentally avoiding migration and loss problems caused by physical blending. The fungicide resistance lifespan is comparable to the coating lifespan, with no release of small-molecule fungicides, making it environmentally friendly and compliant with green chemistry and sustainable development requirements. It is particularly suitable for sensitive fields such as medical devices, children's products, and food contact surfaces.

[0051] This invention employs an irradiation-initiated free radical polymerization strategy, which can be carried out at low temperatures, consumes little energy, requires little or no chemical initiator, and reduces the generation of VOCs and byproducts, making it an environmentally friendly and clean production process.

[0052] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0053] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A long-lasting anti-mildew coating and its preparation method, characterized in that: The coating comprises component A and component B, wherein: Component A is a polyisocyanate curing agent; Component B is prepared through the following steps: Step 1: Preparation of antifungal functional monomers containing polymerizable double bonds Isothiazolinone derivatives and polymerization inhibitor hydroquinone are added to a polar aprotic solvent such as DMF. The mixture is heated to 40-50°C and stirred until completely dissolved. Then, triethylamine is slowly added dropwise while stirring for 20-30 minutes to deprotonate and activate the imino group of the isothiazolinone derivative. The system is then heated to 55-65°C, and excess glycidyl methacrylate is slowly added dropwise. After the addition is complete, the reaction is maintained at this temperature for 4-6 hours until the characteristic peak of epoxy in infrared detection is significantly weakened and the epoxy value titration shows that the reaction is basically complete. After the reaction is completed, the mixture is cooled to room temperature, and a small amount of insoluble matter is removed by filtration to obtain a polymerizable functional monomer containing an isothiazolinone structure. Step 2: Radiation preparation of the base resin for anti-mildew coating Using alkyl acrylate monomers, hydroxyl-containing acrylate monomers, other functional monomers, and the anti-mildew functional monomers prepared in step one as raw materials, they are dissolved in an appropriate amount of solvent and α-methylstyrene dimer is added as a chain transfer agent to prepare a reaction solution. The reaction solution is placed under an irradiation device for radiation polymerization. After the reaction is completed, the solvent and low molecular weight products are removed by distillation to obtain an anti-mildew hydroxyl acrylic resin with a narrow molecular weight distribution, uniform hydroxyl distribution, and no chemical initiator residue. This resin is the base resin of the subsequent component B. Step 3: Preparation of Anti-mildew Coating The base resin, stabilizer, pigments and fillers, leveling agent, defoamer and solvent obtained in step two are mixed evenly according to the coating formula to prepare component B coating slurry; Step 4: Coating Application and Curing The B component, which has undergone step three, is mixed with the A component at a -NCO / -OH equivalent ratio and coated onto the substrate surface. The mixture then undergoes a curing reaction at ambient temperature to form a polyurethane coating with a three-dimensional network structure.

2. The long-lasting anti-mildew coating and its preparation method according to claim 1, characterized in that: The ratio of the -NCO / -OH equivalents of component B and component A is 1.05-1.15:

1.

3. The long-lasting anti-mildew coating and its preparation method according to claim 1, characterized in that: The polyisocyanate curing agent is one or more of TDI, MDI, HDI or IPDI.

4. The long-lasting anti-mildew coating and its preparation method according to claim 1, characterized in that: In step two, the alkyl acrylate monomers are methyl methacrylate or butyl acrylate; the hydroxyl-containing acrylate monomers are hydroxyethyl acrylate or hydroxypropyl acrylate; and the other functional monomers are (meth)acrylic acid or styrene.

5. The long-lasting anti-mildew coating and its preparation method according to claim 1, characterized in that: The isothiazolinone derivatives are one or more of methylisothiazolinone, benzisothiazolinone, n-octylisothiazolinone, and chloromethylisothiazolinone.

6. The long-lasting anti-mildew coating and its preparation method according to claim 1, characterized in that: After double bond functionalization modification, the antifungal monomer isothiazolinone derivative possesses free radical polymerization activity and can directly copolymerize with acrylate monomers to form polymer chains during subsequent radiation polymerization.

7. The long-lasting anti-mildew coating and its preparation method according to claim 1, characterized in that: In step two, the irradiation reaction is carried out under an inert atmosphere using... 60 Co-γ ray polymerization involves controlling the irradiation dose, time, and temperature to induce free radical copolymerization of the monomers.

Images