Anti-corrosion matting baking varnish for metal products and preparation method of anti-corrosion matting baking varnish

Abstract

The invention relates to the technical field of stoving varnish, in particular to metal product anti-corrosion matting stoving varnish and a preparation method thereof.The metal product anti-corrosion matting stoving varnish is characterized in that a cross-linked network formed by thermosetting acrylic resin, partially methylated amino resin and blocked isocyanate is matched with hydrophobic silicon dioxide matting powder and a fluorine-containing thermoplastic polymer to form a compact hydrophobic barrier layer; physical barrier and active water repellency are provided; zinc phosphate forms a chemical passivation corrosion inhibition layer to provide electrochemical protection and interface stability. In conclusion, the comprehensive corrosion resistance (salt fog resistance, water resistance, heat and humidity resistance and chemical resistance) and pollution resistance are greatly improved while a good matting effect is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of baking varnish, and in particular to an anti-corrosion matting baking varnish for metal products and a preparation method thereof. Background Art

[0002] Metal plate baking varnishing is a coating process that forms a film on the surface of metal plates. Primarily using baking technology, a color-treated paint is sprayed onto the metal surface and then cured at high temperatures to form a film. This film protects the metal surface from scratches and rust, while also providing excellent aesthetics and maintenance.

[0003] Currently, amino baking varnishes on the market generally have poor scratch resistance, water resistance, and chemical resistance, which are difficult to solve. In addition, the chemical resistance of normally glossy baking varnishes with good chemical resistance will be significantly deteriorated after being made into matte products. The lower the gloss, the worse the chemical resistance. This is mainly due to the addition of a lot of matting powder. Existing matting products are mostly based on traditional inorganic silica (matting powder). These matting powders float on the surface of the coating, which can cause the surface of the paint film to become rough and significantly reduce its surface gloss. The presence of matting powder allows water to penetrate the originally dense coating film. In addition, the presence of many hydrophilic silanol groups on the surface of the matting powder makes it easier for water and chemicals to penetrate into the coating film, resulting in a significant decrease in the chemical resistance, water resistance, and dirt resistance of the coating film. Summary of the Invention

[0004] The purpose of the present invention is to address the deficiencies in the prior art and provide an anti-corrosion matt baking varnish for metal products having both matt properties and chemical resistance and a preparation method thereof.

[0005] The purpose of the present invention is achieved through the following technical solution: A metal product anti-corrosion matt paint, which is composed of the following raw materials in parts by weight:

[0006] 55-60 parts of thermosetting acrylic resin

[0007] 15-20 parts of partially methylated amino resin

[0008] 5 parts blocked isocyanate

[0009] 5-8 parts of acrylic modified epoxy resin

[0010] 4-6 parts hydrophobic silica matting powder

[0011] 1-3 parts of fluorinated thermoplastic polymer dispersion

[0012] 1-2 parts polymer dispersant

[0013] 4-7 parts zinc phosphate

[0014] Wetting agent 0.5-1.5 parts

[0015] 0.1-0.3 parts of leveling agent

[0016] 5-15 parts of organic solvent.

[0017] The hydrophobic silica matting powder is a product of Japanese Fuji model SLIFSPB 4004.

[0018] The fluorine-containing thermoplastic polymer dispersion is a product of the American 3M model number PFA6900GZ.

[0019] The polymer dispersant is a polyurethane block copolymer, and the BYK model is BYK-2152.

[0020] The wetting agent is polyether-modified polysiloxane, and TEGO Wet 270 is used.

[0021] Wherein, the leveling agent is TEGO Flow 300.

[0022] The organic solvent is propylene glycol methyl ether acetate, methyl n-amyl ketone and n-butanol in a volume ratio of (5-6): (3-4): 2.

[0023] A method for preparing an anti-corrosion matt baking varnish for metal products comprises the following process steps:

[0024] Step 1, preparing a first mixture: adding a formulated amount of a thermosetting acrylic resin, a partially methylated amino resin, a blocked isocyanate, an acrylic modified epoxy resin, a polymer dispersant, zinc phosphate, and half the volume of an organic solvent to a container, and then stirring and mixing at a certain speed for a certain time to obtain a first mixture;

[0025] Step 2, preparing a second mixture: adding a formulated amount of hydrophobic silica matting powder and a wetting agent to the first mixture obtained in step 1, and then stirring and mixing at a certain speed for a certain time to obtain a second mixture;

[0026] Step 3, preparing the product: adding the formulated amount of leveling agent, fluorine-containing thermoplastic polymer dispersion and remaining organic solvent to the second mixture obtained in step 2, and then stirring and mixing at a certain speed for a certain time to obtain the anti-corrosion matte baking paint for metal products.

[0027] wherein, in the step 1, the mixture is stirred and mixed at a speed of 1200 rpm to 1300 rpm for 3 min to 8 min to obtain a first mixture;

[0028] In the step 2, stirring and mixing at a speed of 900 rpm to 1100 rpm for 20 min to 40 min to obtain a second mixture;

[0029] In the step 3, the mixture is stirred and mixed at a rotation speed of 550 rpm to 650 rpm for 10 min to 20 min to obtain the anti-corrosion matte baking varnish for metal products.

[0030] The thermosetting acrylic resin of the present invention is used as the main film-forming substance, providing good hardness, gloss (properly controlled), weather resistance, and gloss and color retention. The thermosetting acrylic resin is a product of DIC model ZHB-213.

[0031] The partially methylated amino resin in this invention serves as the primary crosslinking agent, reacting with the hydroxyl groups of the acrylic resin to form a dense network structure. Partially methylated types generally exhibit improved reactivity, hardness, gloss, and chemical resistance while maintaining a certain degree of flexibility. The partially methylated amino resin is Cymel 325.

[0032] The blocked isocyanate of the present invention can be unblocked at the same temperature as the amino resin crosslinking, providing additional crosslinking points (reacting with hydroxyl, amino, and even carboxyl groups), significantly increasing the crosslink density and compensating for the loss of physical properties (hardness, abrasion resistance, scratch resistance) and chemical resistance that may be caused by the addition of matting agent. The blocked isocyanate used is Asahi Kasei MF-K60X.

[0033] The acrylic acid-modified epoxy resin of the present invention, whose epoxy groups can participate in the curing of acrylic acid / amino systems (via hydroxyl or carboxyl groups), has better compatibility and reactivity, and more effectively improves chemical resistance. The introduced epoxy resin segments significantly enhance the paint film's adhesion (especially to metal substrates), chemical resistance (particularly acid and alkali resistance), and corrosion resistance. The acrylic acid modification improves compatibility with the main acrylic resin and outdoor weathering resistance. The acrylic acid-modified epoxy resin was Guangdong Keding MR1487W.

[0034] The polymer dispersant of the present invention is a polyurethane block copolymer, which can simultaneously anchor zinc phosphate and hydrophobic matting powder through -PO4 3 - Electrostatically adsorb zinc phosphate, which wraps the hydrophobic matting powder through the hydrophobic chain, ensuring that the hydrophobic matting powder, zinc phosphate and other fillers are stably dispersed in the resin system to prevent flocculation and sedimentation.

[0035] The hydrophobic silica matting powder of the present invention significantly reduces the hydrophilic silanol groups on the surface, thereby reducing the wettability and permeability of water, which is a fundamental measure to improve water resistance and chemical resistance.

[0036] The fluorinated thermoplastic polymer dispersion described in the present invention is a water-based fluorinated thermoplastic polymer dispersion with excellent water resistance, scratch resistance, and corrosion resistance. It has extremely low surface energy and excellent chemical and stain resistance. Its addition can further reduce the surface energy of the paint film, forming a hydrophobic and oleophobic surface similar to the "lotus effect," effectively blocking the intrusion of water, chemicals, and stains, and strongly complementing the effect of hydrophobic matting powder. The hydrophobic surface of the hydrophobic silica matting powder is more compatible with the fluorinated thermoplastic polymer dispersion, jointly creating a low surface energy environment and avoiding the problem of the hydrophilic matting powder becoming a "stain adsorption site." The combination of the two achieves excellent stain resistance and easy-to-clean properties on the matting surface.

[0037] The zinc phosphate of this invention is a classic active anti-rust pigment, providing dual corrosion protection mechanisms: sacrificial anodic protection and forming a passive film. It synergistically enhances corrosion resistance, particularly salt spray resistance, when combined with acrylic acid-modified epoxy resin. The zinc phosphate of this invention has a fineness of ≤15 μm.

[0038] The wetting agent described in the present invention can reduce the surface tension of the coating, improve the wetting of the substrate (metal) and pigment / filler surface, and reduce defects such as shrinkage cavities and pinholes. It is particularly important for systems containing hydrophobic matting agents and fluoropolymers, preventing surface defects caused by surface tension mismatch.

[0039] The combination of solvents of the present invention can simultaneously dissolve acrylic / epoxy / amino resins and control the volatilization gradient, thereby avoiding poor leveling caused by excessive surface drying.

[0040] The present invention has the following beneficial effects: The cross-linked network formed by thermosetting acrylic resin, partially methylated amino resin, and blocked isocyanate, combined with hydrophobic silica matting powder and fluorinated thermoplastic polymer, forms a dense hydrophobic barrier layer, providing physical barrier and active water repellency. Zinc phosphate forms a chemically passivating corrosion inhibitor layer, providing electrochemical protection and interfacial stability. In summary, while achieving excellent matting effects, the present invention significantly improves its comprehensive corrosion resistance (salt spray resistance, water resistance, moisture and heat resistance, and chemical resistance) and stain resistance. DETAILED DESCRIPTION

[0041] The present invention is further described with reference to the following examples.

[0042] Example 1

[0043] A metal product anti-corrosion matt baking varnish, which is composed of the following raw materials in parts by weight:

[0044]

[0045] The hydrophobic silica matting powder is a product of Japanese Fuji model SLIFSPB 4004.

[0046] The fluorine-containing thermoplastic polymer dispersion is a product of the American 3M model number PFA6900GZ.

[0047] The polymer dispersant is a polyurethane block copolymer, and the BYK model is BYK-2152.

[0048] The wetting agent is polyether-modified polysiloxane, and TEGO Wet 270 is used.

[0049] Wherein, the leveling agent is TEGO Flow 300.

[0050] The organic solvent is propylene glycol methyl ether acetate, methyl n-amyl ketone and n-butanol in a volume ratio of 6:3:2.

[0051] A method for preparing an anti-corrosion matt baking varnish for metal products comprises the following process steps:

[0052] Step 1, preparing a first mixture: adding a formulated amount of a thermosetting acrylic resin, a partially methylated amino resin, a blocked isocyanate, an acrylic modified epoxy resin, a polymer dispersant, zinc phosphate, and half the volume of an organic solvent to a container, and then stirring and mixing at a certain speed for a certain time to obtain a first mixture;

[0053] Step 2, preparing a second mixture: adding a formulated amount of hydrophobic silica matting powder and a wetting agent to the first mixture obtained in step 1, and then stirring and mixing at a certain speed for a certain time to obtain a second mixture;

[0054] Step 3, preparing the product: adding the formulated amount of leveling agent, fluorine-containing thermoplastic polymer dispersion and remaining organic solvent to the second mixture obtained in step 2, and then stirring and mixing at a certain speed for a certain time to obtain the anti-corrosion matte baking paint for metal products.

[0055] Wherein, in the step 1, the mixture is stirred at a speed of 1200 rpm for 8 minutes to obtain a first mixture;

[0056] In the step 2, the mixture was stirred at a speed of 900 rpm for 20 minutes to obtain a second mixture;

[0057] In the step 3, the mixture is stirred and mixed at a rotation speed of 550 rpm for 20 minutes to obtain the anti-corrosion matte baking varnish for metal products.

[0058] The thermosetting acrylic resin is a product with a DIC model of ZHB-213.

[0059] The partially methylated amino resin is cymel 325.

[0060] The blocked isocyanate is Asahi Kasei MF-K60X.

[0061] The acrylic acid modified epoxy resin adopts Guangdong Keding MR1487W.

[0062] Example 2

[0063] A metal product anti-corrosion matt baking varnish, which is composed of the following raw materials in parts by weight:

[0064] 58 parts of thermosetting acrylic resin

[0065] 18 parts of partially methylated amino resin

[0066] 5 parts blocked isocyanate

[0067]

[0068] The hydrophobic silica matting powder is a product of Japanese Fuji model SLIFSPB 4004.

[0069] The fluorine-containing thermoplastic polymer dispersion is a product of the American 3M model number PFA6900GZ.

[0070] The polymer dispersant is a polyurethane block copolymer, and the BYK model is BYK-2152.

[0071] The wetting agent is polyether-modified polysiloxane, and TEGO Wet 270 is used.

[0072] Wherein, the leveling agent is TEGO Flow 300.

[0073] The organic solvent is propylene glycol methyl ether acetate, methyl n-amyl ketone and n-butanol in a volume ratio of 5:3:2.

[0074] A method for preparing an anti-corrosion matt baking varnish for metal products comprises the following process steps:

[0075] Step 1, preparing a first mixture: adding a formulated amount of a thermosetting acrylic resin, a partially methylated amino resin, a blocked isocyanate, an acrylic modified epoxy resin, a polymer dispersant, zinc phosphate, and half the volume of an organic solvent to a container, and then stirring and mixing at a certain speed for a certain time to obtain a first mixture;

[0076] Step 2, preparing a second mixture: adding a formulated amount of hydrophobic silica matting powder and a wetting agent to the first mixture obtained in step 1, and then stirring and mixing at a certain speed for a certain time to obtain a second mixture;

[0077] Step 3, preparing the product: adding the formulated amount of leveling agent, fluorine-containing thermoplastic polymer dispersion and remaining organic solvent to the second mixture obtained in step 2, and then stirring and mixing at a certain speed for a certain time to obtain the anti-corrosion matte baking paint for metal products.

[0078] wherein, in the step 1, the mixture is stirred and mixed at a rotation speed of 1250 rpm for 6 minutes to obtain a first mixture;

[0079] In the step 2, the mixture was stirred at a speed of 1000 rpm for 30 minutes to obtain a second mixture;

[0080] In the step 3, the mixture is stirred and mixed at a rotation speed of 600 rpm for 15 minutes to obtain the anti-corrosion matte baking varnish for metal products.

[0081] The thermosetting acrylic resin is a product with a DIC model of ZHB-213.

[0082] The partially methylated amino resin is cymel 325.

[0083] The blocked isocyanate is Asahi Kasei MF-K60X.

[0084] The acrylic acid modified epoxy resin adopts Guangdong Keding MR1487W.

[0085] Example 3

[0086] A metal product anti-corrosion matt baking varnish, which is composed of the following raw materials in parts by weight:

[0087]

[0088] The hydrophobic silica matting powder is a product of Japanese Fuji model SLIFSPB 4004.

[0089] The fluorine-containing thermoplastic polymer dispersion is a product of the American 3M model number PFA6900GZ.

[0090] The polymer dispersant is a polyurethane block copolymer, and the BYK model is BYK-2152.

[0091] The wetting agent is polyether-modified polysiloxane, and TEGO Wet 270 is used.

[0092] Wherein, the leveling agent is TEGO Flow 300.

[0093] The organic solvent is propylene glycol methyl ether acetate, methyl n-amyl ketone and n-butanol in a volume ratio of 6:4:2.

[0094] A method for preparing an anti-corrosion matt baking varnish for metal products comprises the following process steps:

[0095] Step 1, preparing a first mixture: adding a formulated amount of a thermosetting acrylic resin, a partially methylated amino resin, a blocked isocyanate, an acrylic modified epoxy resin, a polymer dispersant, zinc phosphate, and half the volume of an organic solvent to a container, and then stirring and mixing at a certain speed for a certain time to obtain a first mixture;

[0096] Step 2, preparing a second mixture: adding a formulated amount of hydrophobic silica matting powder and a wetting agent to the first mixture obtained in step 1, and then stirring and mixing at a certain speed for a certain time to obtain a second mixture;

[0097] Step 3, preparing the product: adding the formulated amount of leveling agent, fluorine-containing thermoplastic polymer dispersion and remaining organic solvent to the second mixture obtained in step 2, and then stirring and mixing at a certain speed for a certain time to obtain the anti-corrosion matte baking paint for metal products.

[0098] wherein, in the step 1, the mixture is stirred and mixed at a speed of 1300 rpm for 3 minutes to obtain a first mixture;

[0099] wherein, in the step 2, the mixture is stirred and mixed at a speed of 1100 rpm for 20 min to obtain a second mixture;

[0100] Wherein, in the step 3, the mixture is stirred and mixed at a rotation speed of 650 rpm for 10 minutes to obtain the anti-corrosion matte baking paint for metal products.

[0101] The thermosetting acrylic resin is a product with a DIC model of ZHB-213.

[0102] The partially methylated amino resin is cymel 325.

[0103] The blocked isocyanate is Asahi Kasei MF-K60X.

[0104] The acrylic acid modified epoxy resin adopts Guangdong Keding MR1487W.

[0105] Comparative Example 1

[0106] The difference between Comparative Example 1 and Example 2 is that this comparative example does not use acrylic acid-modified epoxy resin, but uses bisphenol A epoxy resin.

[0107] Comparative Example 2

[0108] The difference between Comparative Example 2 and Example 2 is that the fluorine-containing thermoplastic polymer dispersion is not included in this comparative example, but is directly deleted.

[0109] Comparative Example 3

[0110] The difference between Comparative Example 3 and Example 2 is that this comparative example does not use a polymer dispersant, but uses the commercially available DS-165 dispersant of Tuyile.

[0111] The experimental data of Examples 1-3 of the present invention and Comparative Examples 1-3 are shown in the table below.

[0112]

[0113]

[0114] As can be seen from the above table: Comparative Example 1 does not use acrylic modified epoxy resin, but instead uses bisphenol A epoxy resin. This may be due to the poor compatibility of bisphenol A epoxy resin with the acrylic resin / amino resin system. In addition, the epoxy groups of bisphenol A epoxy resin lack effective reactive groups to react with it at conventional paint baking temperatures (usually 120-180°C). The unreacted epoxy resin will become a "soft spot" or "weak point" in the paint film, which will reduce the overall chemical resistance and strength. Comparative Example 2 does not use a fluorinated thermoplastic polymer dispersion. First, it cannot further reduce the surface energy of the paint film to form a hydrophobic and oleophobic surface similar to the "lotus effect" that effectively blocks the intrusion of water, chemicals, and stains, thereby reducing the overall chemical resistance. Second, the hydrophobic surface of the hydrophobic silica matting powder cannot jointly create a low surface energy environment with the fluorinated thermoplastic polymer dispersion, and ultimately becomes a "stain adsorption site." Comparative Example 3 does not use a polymer dispersant, but instead uses a commercially available dispersant. It is impossible to anchor zinc phosphate and hydrophobic matting agent at the same time, and thus it is impossible to ensure that fillers such as hydrophobic matting agent and zinc phosphate are stably dispersed in the resin system, which ultimately affects the chemical resistance of the product.

[0115] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. An anti-corrosion matt paint for metal products, characterized by: It is composed of the following raw materials in parts by weight:

2. The anti-corrosion matte baking varnish for metal products according to claim 1, characterized in that: The hydrophobic silica matting powder is a product of Japanese Fuji model SLIFSPB 4004.

3. The anti-corrosion matte baking varnish for metal products according to claim 1, characterized in that: The fluorine-containing thermoplastic polymer dispersion is a product of 3M, USA, model number PFA6900GZ.

4. The anti-corrosion matte baking varnish for metal products according to claim 1, characterized in that: The polymer dispersant is a polyurethane block copolymer, and the BYK model is BYK-2152.

5. The anti-corrosion matte baking varnish for metal products according to claim 1, characterized in that: The wetting agent is polyether-modified polysiloxane, and TEGO Wet 270 is used.

6. The anti-corrosion matte baking varnish for metal products according to claim 1, characterized in that: The leveling agent used is TEGO Flow 300.

7. The anti-corrosion matte baking varnish for metal products according to claim 1, characterized in that: The organic solvent is propylene glycol methyl ether acetate, methyl n-amyl ketone and n-butanol in a volume ratio of (5-6): (3-4):

2.

8. The method for preparing the anti-corrosion matte baking varnish for metal products according to claim 1, characterized in that: It includes the following process steps: Step 1, preparing a first mixture: adding a formulated amount of a thermosetting acrylic resin, a partially methylated amino resin, a blocked isocyanate, an acrylic modified epoxy resin, a polymer dispersant, zinc phosphate, and half the volume of an organic solvent to a container, and then stirring and mixing at a certain speed for a certain time to obtain a first mixture; Step 2, preparing a second mixture: adding a formulated amount of hydrophobic silica matting powder and a wetting agent to the first mixture obtained in step 1, and then stirring and mixing at a certain speed for a certain time to obtain a second mixture; Step 3, preparing the product: adding the formulated amount of leveling agent, fluorine-containing thermoplastic polymer dispersion and remaining organic solvent to the second mixture obtained in step 2, and then stirring and mixing at a certain speed for a certain time to obtain the anti-corrosion matte baking paint for metal products.

9. The method for preparing the anti-corrosion matte baking varnish for metal products according to claim 8, characterized in that: In the step 1, stirring and mixing at a speed of 1200 rpm to 1300 rpm for 3 min to 8 min to obtain a first mixture; In the step 2, stirring and mixing at a speed of 900 rpm to 1100 rpm for 20 min to 40 min to obtain a second mixture; In the step 3, the mixture is stirred and mixed at a rotation speed of 550 rpm to 650 rpm for 10 min to 20 min to obtain the anti-corrosion matte baking varnish for metal products.

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