Water-based mildew-proof gloss oil and preparation method thereof

Abstract

The invention provides water-based mildew-proof gloss oil and a preparation method thereof. The gloss oil is prepared from the following components: 30wt%-50wt% of water-based acrylic resin, 5wt%-15wt% of pigment, 2wt%-6wt% of a mildew inhibitor, 0.1 wt%-5wt% of a wetting agent, 0.1 wt%-5wt% of a flatting agent, 0.1 wt%-5wt% of a defoaming agent, 5wt%-15wt% of absolute ethyl alcohol and the balance of water. The water-based mildewproof gloss oil provided by the invention takes water as a solvent, is environment-friendly and non-toxic, has good film-forming property, can enable a paperboard to have excellent mildewproof property after being coated, and tests show that the mildewproof gloss oil provided by the invention has an antibacterial rate of 100% on nine mixed molds, achieves a grade I antibacterial effect, can effectively prevent the growth of molds in the storage and use processes of the paperboard, and has good mildew resistance. And the preparation method of the gloss oil is simple, convenient and feasible, is suitable for industrial production, and has a wide market application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of coating materials, in particular to a water-based mildew-proof varnish for cardboard and a preparation method thereof. Background Art

[0002] In the field of packaging and printing, varnish is usually used to polish the product surface in order to enhance the protective performance and improve the visual and tactile experience. Existing varnishes mainly include UV varnish, oil-based varnish and water-based varnish. UV varnish is a solvent-free varnish. After being evenly applied to the surface of the product, it undergoes a polymerization reaction and rapidly solidifies under the irradiation of ultraviolet light of a certain wavelength, forming a bright film layer on the surface of the product. Oil-based varnish uses benzene, esters and alcohols as solvents. After being evenly applied to the surface of the product, it is heated to evaporate the solvent in the varnish, and the film-forming resin remains on the surface of the product to form a bright film layer. Water-based varnish is a varnish made of water-based film-forming resin as the main agent, water as the solvent, and various additives. After being evenly applied to the surface of the product, it is heated to evaporate the water in the varnish, and the film-forming resin remains on the surface of the product to form a bright film layer. Water-based varnish uses water as solvent, has no VOC emissions, meets the hygiene standards for food and pharmaceutical packaging, and has excellent environmental performance.

[0003] During the production and application of cardboard, varnish treatment is often required to enhance its gloss, abrasion resistance, and other properties. However, most existing cardboard varnishes are susceptible to mold growth, which affects the cardboard's storage and performance. This is especially true for cardboard stored in humid environments for extended periods or improperly. Mold growth can lead to cardboard deterioration and damage, resulting in economic losses. Furthermore, traditional varnishes are mostly solvent-based and contain high levels of volatile organic compounds (VOCs), which are harmful to the environment and human health. Therefore, the development of an environmentally friendly and mold-resistant varnish is of great significance to the cardboard industry. Summary of the Invention

[0004] In view of this, in order to solve the technical problems that existing varnishes for cardboard have poor environmental performance and poor mildew resistance, the present invention proposes a water-based mildew-proof varnish with low cost, good printing performance and long-lasting antibacterial and mildew resistance.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a water-based mildew-proof varnish, which comprises the following components by weight percentage:

[0007] 30wt%-50wt% of water-based acrylic resin, 5wt%-15wt% of pigment, 2wt%-6wt% of mildewproof agent, 0.1wt%-5wt% of wetting agent, 0.1wt%-5wt% of leveling agent, 0.1wt%-5wt% of defoaming agent, 5wt%-15wt% of anhydrous ethanol, and the balance is water.

[0008] Preferably, the pigment is one or both of titanium dioxide and lithopone.

[0009] Preferably, the antifungal agent is selected from two or more of IPBC, natamycin, potassium sorbate, tea polyphenols, monolaurin, and nano zinc oxide.

[0010] Preferably, the anti-mold agent is natamycin and tea polyphenols, and the mass ratio of natamycin to tea polyphenols is 1:(50-500).

[0011] Preferably, the wetting agent is one or both of polyether-modified siloxanes and polyoxyethylene ethers.

[0012] Preferably, the leveling agent is a polyether-modified siloxane leveling agent or a modified acrylate copolymer leveling agent.

[0013] Preferably, the defoaming agent is one or both of an organosilicon defoaming agent and a mineral oil defoaming agent.

[0014] The preparation method of the above-mentioned water-based mildew-proof varnish comprises the following steps:

[0015] 1) Weighing the water-based acrylic resin, pigment, mildew inhibitor, wetting agent, leveling agent, defoaming agent, and anhydrous ethanol respectively for use;

[0016] 2) adding the water-based acrylic resin and pigment to water, starting stirring, controlling the speed at 1000 rpm to 2000 rpm, and after stirring evenly, sequentially adding the anhydrous ethanol and mildew inhibitor, and continuing stirring for 10 min to 30 min;

[0017] 3) Continue adding the leveling agent, wetting agent and defoaming agent, control the speed at 1000r / min-2000r / min, and stir for 10min-20min;

[0018] 4) adding water to adjust the viscosity of the varnish to 100 mPa·s-500 mPa·s, and then filtering to obtain the water-based mildew-proof varnish.

[0019] The present invention provides a water-based mildew-proof varnish, comprising: 30wt%-50wt% water-based acrylic resin, 5wt%-15wt% pigment, 2wt%-6wt% mildew-proof agent, 0.1wt%-5wt% wetting agent, 0.1wt%-5wt% leveling agent, 0.1wt%-5wt% defoaming agent, 5wt%-15wt% anhydrous ethanol, and the balance being water. By rationally combining, non-toxic and harmless antibacterial and mildew-proof materials are added to the varnish formula to achieve a long-lasting antibacterial and mildew-proof effect, while not affecting the basic properties of the varnish, allowing it to maintain good printing adaptability. It has been verified that the mildew-proof varnish in this application has an antibacterial rate of 100% against nine mixed molds, effectively solving the problem of poor mildew-proofing effect of existing water-based varnishes. Its application on cardboard can greatly improve product quality and achieve a long-lasting antibacterial and mildew-proof effect. Furthermore, the preparation process of the mildew-proof varnish in this application is simple and easy, has good economic efficiency, is suitable for industrial production, and has broad market application prospects. DETAILED DESCRIPTION

[0020] The present invention provides a water-based mildew-proof varnish, which comprises the following components by weight percentage:

[0021] 30wt%-50wt% of water-based acrylic resin, 5wt%-15wt% of pigment, 2wt%-6wt% of mildewproof agent, 0.1wt%-5wt% of wetting agent, 0.1wt%-5wt% of leveling agent, 0.1wt%-5wt% of defoaming agent, 5wt%-15wt% of anhydrous ethanol, and the balance is water.

[0022] In the present invention, the source of the water-based acrylic resin is not particularly limited; commercially available products can be used. Water-based acrylic resin is an environmentally friendly resin product with advantages such as being non-toxic, odorless, high gloss, and excellent thermal stability. During film formation, the carboxyl and hydroxyl groups in the water-based acrylic resin undergo a self-reactive crosslinking reaction, thereby improving film performance.

[0023] In the present invention, the pigment is preferably one or both of titanium dioxide and lithopone. Lithopone, also known as lithopone, is a white powder, a mixture of zinc sulfide and barium sulfate, and an inorganic pigment used for coloring varnishes. The sources of titanium dioxide and lithopone are not particularly limited; commercially available products may be used.

[0024] In the present invention, the antifungal agent is preferably selected from two or more of IPBC, natamycin, potassium sorbate, tea polyphenols, monolaurin, and nano-zinc oxide. More preferably, the antifungal agent is preferably selected from two or three of IPBC, natamycin, potassium sorbate, tea polyphenols, monolaurin, and nano-zinc oxide.

[0025] In the present invention, the antifungal agent is more preferably natamycin and tea polyphenols, with the mass ratio of natamycin to tea polyphenols being 1:(50-500). The bactericidal principle of natamycin is primarily through its action on the cell membrane. Natamycin specifically binds to ergosterol on the fungal cell membrane to form a polyene-sterol complex. This complex alters the structure and function of the cell membrane, increasing its permeability and allowing the leakage of important intracellular substances such as amino acids and electrolytes, thereby interfering with the normal metabolism and physiological functions of the fungal cells, inhibiting fungal growth, and ultimately leading to fungal death. The antibacterial component is stable and the antibacterial effect is long-lasting. A low addition rate can ensure the product's excellent antibacterial effect while having minimal impact on the transparency of the varnish. The addition of the antibacterial and antifungal material does not affect the transparency of the water-based varnish itself, nor does it adversely affect the color of the printed product. The bactericidal mechanism of tea polyphenols is mainly to destroy the cell membrane structure. The catechins and other components in tea polyphenols are lipophilic and can be adsorbed on the bacterial cell membrane, destroying the integrity and permeability of the cell membrane, allowing the leakage of intracellular substances, interfering with the normal metabolism of bacteria, and thus inhibiting bacterial growth and reproduction. In addition, tea polyphenols can inhibit the activity of various enzymes in bacteria, such as dehydrogenases and proteases. These enzymes are crucial for bacterial metabolism, nutrient uptake, and biosynthesis. Inhibited enzyme activity will hinder bacterial growth and reproduction. In addition, tea polyphenols are natural antioxidants that can scavenge free radicals produced during bacterial metabolism or prevent the generation of free radicals. Excessive free radicals can damage bacterial cells, thereby indirectly playing a bactericidal role. Natamycin is a highly effective antifungal agent with specific effects against molds, but weaker inhibitory effects against bacteria. Tea polyphenols (especially catechins) have a broad-spectrum antimicrobial activity (inhibiting some bacteria and fungi), and the combination of the two can expand the antimicrobial range. Tea polyphenols are strong antioxidants that scavenge free radicals and slow oxidation reactions. Natamycin is susceptible to decomposition under light and high temperatures, and the antioxidant properties of tea polyphenols may help protect the stability of natamycin and prolong its effective duration. The combination of these two antifungal agents combines the advantages of each, offsetting their respective shortcomings, achieving a complementary effect, significantly improving product quality, and providing long-lasting antibacterial and antifungal effects.

[0026] In the present invention, the wetting agent is preferably one or both of polyether-modified siloxanes and polyoxyethylene ethers, more preferably Silok 8000, DS-270TW, TEGO Wet 270, SY-8029, fatty alcohol polyoxyethylene ether, or isomeric tridecanol polyoxyethylene ether, with SY-8029 ultimately selected. Wetting agents can aid in uniform dispersion of pigments and fillers during the production process, prevent agglomeration, enhance varnish stability and gloss, improve application performance, reduce coating resistance, and facilitate smoother brushing or spraying.

[0027] In the present invention, the leveling agent is preferably a polyether-modified silicone leveling agent or a modified acrylate copolymer leveling agent, more preferably one of TEGO-410, Hyperlev F66, LT-8081, or HT-375S, with TEGO-410 ultimately selected. This polyether-modified silicone leveling agent helps evenly spread the varnish on the paperboard surface, eliminating brush or roller marks during the coating process, resulting in a smooth coating and improving the paperboard's appearance.

[0028] In the present invention, the defoamer is preferably one or both of a silicone defoamer and a mineral oil defoamer, more preferably one of BYK-024, SAG 1000, IRW-A000G, GX-8810, and Deqian 902, with Deqian 902 being the final choice. The defoamer can quickly eliminate bubbles, ensuring the stability of the varnish and the coating effect.

[0029] In the present invention, the anhydrous ethanol can accelerate the film-forming and drying efficiency of the varnish by volatilization, help dissolve or disperse the functional components (such as mildew inhibitors) in the system, improve stability, adjust surface tension, optimize the adhesion between the varnish and the substrate, and reduce defects such as shrinkage holes.

[0030] In the present invention, in addition to the above ingredients, the balance is water. Water serves as a solvent and dispersion medium, allowing the various ingredients to be evenly dispersed in the aqueous system, facilitating coating operations, while also reducing the VOC content of the varnish, meeting environmental protection requirements.

[0031] The preparation method of the above-mentioned water-based mildew-proof varnish comprises the following steps:

[0032] 1) Weighing the water-based acrylic resin, pigment, mildew inhibitor, wetting agent, leveling agent, defoaming agent, and anhydrous ethanol respectively for use;

[0033] 2) adding the water-based acrylic resin and pigment to water, starting stirring, controlling the speed at 1000 rpm to 2000 rpm, and after stirring evenly, sequentially adding the anhydrous ethanol and mildew inhibitor, and continuing stirring for 10 min to 30 min;

[0034] 3) Continue adding the leveling agent, wetting agent and defoaming agent, control the speed at 1000r / min-2000r / min, and stir for 10min-20min;

[0035] 4) adding water to adjust the viscosity of the varnish to 100 mPa·s-500 mPa·s, and then filtering to obtain the water-based mildew-proof varnish.

[0036] In the present invention, the filtration is preferably performed using a 100-200 mesh filter. The filter is used to filter the varnish to remove possible impurities and large particles, ensuring the purity and coating quality of the varnish, and obtaining the final water-based mildew-proof varnish product.

[0037] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0038] Example 1

[0039] A method for preparing a water-based mildew-proof varnish comprises the following steps:

[0040] 1) Weigh 40 wt% of the water-based acrylic resin, 10 wt% of lithopone, 2 wt% of a mildew inhibitor, 5 wt% of Silok 8000, 3 wt% of TEGO-410, 5 wt% of Deqian 902, and 5 wt% of anhydrous ethanol respectively for later use;

[0041] 2) adding the water-based acrylic resin and lithopone to water, starting stirring at a speed of 1500 r / min, and after stirring evenly, sequentially adding the anhydrous ethanol and mildew inhibitor, and continuing stirring for 20 minutes;

[0042] 3) Continue to add the TEGO-410, Silok 8000 and Deqian 902, control the speed at 1500 r / min, and stir for 15 minutes;

[0043] 4) adding water to adjust the viscosity of the varnish to 300 mPa·s, and then filtering to obtain the water-based mildew-proof varnish.

[0044] Example 2

[0045] A method for preparing a water-based mildew-proof varnish comprises the following steps:

[0046] 1) Weigh 30 wt% of the water-based acrylic resin, 10 wt% of lithopone, 3 wt% of a mildew inhibitor, 3 wt% of fatty alcohol polyoxyethylene ether, 5 wt% of TEGO-410, 5 wt% of Deqian 902, and 5 wt% of anhydrous ethanol respectively for later use;

[0047] 2) adding the water-based acrylic resin and lithopone to water, starting stirring at a speed of 1000 r / min, and after stirring evenly, sequentially adding the anhydrous ethanol and mildew inhibitor, and continuing stirring for 20 minutes;

[0048] 3) Continue to add the TEGO-410, fatty alcohol polyoxyethylene ether and Deqian 902, control the speed at 1500r / min, and stir for 15min;

[0049] 4) adding water to adjust the viscosity of the varnish to 100 mPa·s, and then filtering to obtain the water-based mildew-proof varnish.

[0050] Example 3

[0051] A method for preparing a water-based mildew-proof varnish comprises the following steps:

[0052] 1) 50 wt% of the water-based acrylic resin, 10 wt% of lithopone, 4 wt% of a mildew inhibitor, 5 wt% of Silok 8000, 5 wt% of TEGO-410, 5 wt% of Deqian 902, and 5 wt% of anhydrous ethanol were weighed and set aside;

[0053] 2) adding the water-based acrylic resin and lithopone to water, starting stirring at a speed of 1500 r / min, and after stirring evenly, sequentially adding the anhydrous ethanol and mildew inhibitor, and continuing stirring for 20 minutes;

[0054] 3) Continue to add the TEGO-410, Silok 8000 and Deqian 902, control the speed at 1500 r / min, and stir for 15 minutes;

[0055] 4) adding water to adjust the viscosity of the varnish to 500 mPa·s, and then filtering to obtain the water-based mildew-proof varnish.

[0056] Example 4

[0057] A method for preparing a water-based mildew-proof varnish comprises the following steps:

[0058] 1) Weigh 40 wt% of the water-based acrylic resin, 5 wt% of lithopone, 5 wt% of a mildew inhibitor, 1 wt% of fatty alcohol polyoxyethylene ether, 5 wt% of TEGO-410, 3 wt% of Deqian 902, and 5 wt% of anhydrous ethanol respectively for later use;

[0059] 2) adding the water-based acrylic resin and lithopone to water, starting stirring at a speed of 2000 r / min, and after stirring evenly, sequentially adding the anhydrous ethanol and mildew inhibitor, and continuing stirring for 10 minutes;

[0060] 3) Continue to add the TEGO-410, fatty alcohol polyoxyethylene ether and Deqian 902, control the speed at 1500r / min, and stir for 15min;

[0061] 4) adding water to adjust the viscosity of the varnish to 300 mPa·s, and then filtering to obtain the water-based mildew-proof varnish.

[0062] Example 5

[0063] A method for preparing a water-based mildew-proof varnish comprises the following steps:

[0064] 1) Weigh 40 wt% of the water-based acrylic resin, 15 wt% of lithopone, 6 wt% of a mildew inhibitor, 5 wt% of fatty alcohol polyoxyethylene ether, 1 wt% of TEGO-410, 5 wt% of Deqian 902, and 5 wt% of anhydrous ethanol respectively for later use;

[0065] 2) adding the water-based acrylic resin and lithopone to water, starting stirring at a speed of 1500 r / min, and after stirring evenly, sequentially adding the anhydrous ethanol and mildew inhibitor, and continuing stirring for 15 minutes;

[0066] 3) Continue to add the TEGO-410, fatty alcohol polyoxyethylene ether and Deqian 902, control the speed at 1500r / min, and stir for 15min;

[0067] 4) adding water to adjust the viscosity of the varnish to 300 mPa·s, and then filtering to obtain the water-based mildew-proof varnish.

[0068] Comparative Example 1

[0069] In Comparative Example 1, water was used instead of aqueous varnish.

[0070] Comparative Example 2

[0071] In Comparative Example 2, the amount of antifungal agent added was 0, and other conditions were the same as those in Example 1.

[0072] Application and test methods

[0073] After the processing of Examples 1-5 and Comparative Examples 1-2 prepared according to the above steps is completed, a mildew-proof varnish is applied to one of white cardboard, gray cardboard, corrugated cardboard, or single white industrial cardboard. The application test data of the varnish are as follows:

[0074] Construction process: coating (roller coating)

[0075] Mesh: 60-100 lines anilox roller

[0076] Viscosity: Rotational viscometer

[0077] Ph: Benchtop pH meter

[0078] Smoothness: DCP-PHY10k computer-controlled smoothness meter

[0079] Performance of coating after application:

[0080] Gloss: ZGM-1020 (75°) gloss meter;

[0081] Antibacterial test: tested according to the reference standard, antibacterial test standard: GB / T 21866-2008;

[0082] Determination method of antibacterial properties of coatings (paint films) and antibacterial effects;

[0083] Experimental strains: a mixture of nine fungi, including Aspergillus niger, Penicillium oxalicum, Penicillium expansum, Talaromyces funiculosus, Cladosporium oxysporum, Talaromyces verrucosum, Rhizopus stolonifer, Alternaria alternata, and Cladosporium tenuis.

[0084] Experimental cardboard: one of white cardboard, gray cardboard, corrugated cardboard, and single white industrial cardboard;

[0085] The inhibitory effect of adding different proportions of anti-mildew materials on mold and the influence on the performance of varnish in the embodiment are shown in Table 1:

[0086]

[0087] The test results in Table 1 show that the addition of mildew-proof materials has no significant impact on the basic performance of the varnish. However, as the proportion of the added mildew-proof materials increases, the antibacterial rate against the nine mixed fungi increases accordingly. Examples 1-4 achieved an antibacterial rate of ≥90.00% against the nine mixed fungi, achieving Class II antibacterial efficacy, suitable for applications requiring antibacterial efficacy. Example 5 achieved an antibacterial rate of ≥99.00 against the nine mixed fungi, achieving Class I antibacterial efficacy, suitable for applications requiring high antibacterial efficacy. Example 5 represents the optimal ratio. The optimal mildew-proof varnish composition includes 40% water-based acrylic resin, 6% mildew inhibitor, 10% pigment, 5% wetting agent, 5% leveling agent, 5% defoaming agent, 5% anhydrous ethanol, and the balance is water. The optimal mildew-proof varnish formula achieves a 100% antibacterial rate against the nine mixed fungi, achieving Class I antibacterial efficacy. By rationally combining non-toxic and harmless mildew-proof materials in the formulated varnish, this application effectively prevents mold growth on cardboard during storage and use.

[0088] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A water-based mildew-proof varnish, characterized in that: According to weight percentage, it contains the following components: 30wt%-50wt% of water-based acrylic resin, 5wt%-15wt% of pigment, 2wt%-6wt% of mildewproof agent, 0.1wt%-5wt% of wetting agent, 0.1wt%-5wt% of leveling agent, 0.1wt%-5wt% of defoaming agent, 5wt%-15wt% of anhydrous ethanol, and the balance is water.

2. The water-based mildew-proof varnish according to claim 1, characterized in that: The pigment is one or both of titanium dioxide and lithopone.

3. The water-based mildew-proof varnish according to claim 1, characterized in that: The anti-mold agent is selected from two or more of IPBC, natamycin, potassium sorbate, tea polyphenols, monolaurin, and nano zinc oxide.

4. The water-based mildew-proof varnish according to claim 3, characterized in that: The anti-mildew agent is natamycin and tea polyphenols, and the mass ratio of natamycin to tea polyphenols is 1:(50-500).

5. The water-based mildew-proof varnish according to claim 1, characterized in that: The wetting agent is one or both of polyether-modified siloxanes and polyoxyethylene ethers.

6. The water-based mildew-proof varnish according to claim 1, characterized in that: The leveling agent is a polyether-modified siloxane leveling agent or a modified acrylate copolymer leveling agent.

7. The water-based mildew-proof varnish according to claim 1, characterized in that: The defoaming agent is one or both of an organosilicon defoaming agent and a mineral oil defoaming agent.

8. The method for preparing the water-based mildew-proof varnish according to any one of claims 1 to 7, characterized in that: The steps include: 1) Weighing the water-based acrylic resin, pigment, mildew inhibitor, wetting agent, leveling agent, defoaming agent, and anhydrous ethanol respectively for use; 2) adding the water-based acrylic resin and pigment to water, starting stirring, controlling the speed at 1000 rpm to 2000 rpm, and after stirring evenly, sequentially adding the anhydrous ethanol and mildew inhibitor, and continuing stirring for 10 min to 30 min; 3) Continue adding the leveling agent, wetting agent and defoaming agent, control the speed at 1000r / min-2000r / min, and stir for 10min-20min; 4) adding water to adjust the viscosity of the varnish to 100 mPa·s-500 mPa·s, and then filtering to obtain the water-based mildew-proof varnish.

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