A water-based repair adhesive for chemical milling and a preparation method thereof

Abstract

The application discloses a water-based repair adhesive for chemical milling and a preparation method thereof. The water-based repair adhesive is prepared from a main base resin, a filler, a pigment, an additive and a solvent, and has the advantages of green environmental protection, easy construction, separate chemical milling, good compactness, balanced adhesion and peelability, etc. In the chemical milling process, the water-based repair adhesive can repair the defects of the water-based chemical milling adhesive film, and can be quickly dried into a film at room temperature. The separate chemical milling can ensure that the immersion corrosion ratio meets the chemical milling process specification requirements, and the water-based repair adhesive has good peelability after the chemical milling process is completed.

Description

Technical Field

[0001] This invention relates to the field of repair adhesives, specifically to a water-based repair adhesive that can be used for chemical milling and its preparation method. Background Technology

[0002] Repair adhesive is an essential material in the chemical milling (CMM) process for precision workpieces such as aircraft skin. CMM protective coatings can be applied using various methods, including brushing, dipping, roller coating, and airless spraying. Due to the curved or arc-shaped nature of some parts, or the influence of environmental impurities, regardless of the application method, after the CMM protective coating has naturally dried, defects such as pinholes, sand holes, insufficient coating thickness, and uneven thickness will inevitably be found when inspected with a 3-8 kV DC spark leak detector. Airless spraying may result in even more coating defects compared to other methods. Leakage of the CMM fluid at these defects will severely affect the quality of the CMM process, and may even lead to the scrapping of parts. Sometimes, the damaged area is large, or the defect is located precisely at the cut edge. In such cases, the repair adhesive must be able to perform individual CMM milling. Furthermore, to shorten processing time and ensure the progress of the process, using water-based CMM-compatible repair adhesives to repair and recoat defective areas is highly effective in ensuring the quality of CMM-milled workpieces. Water-based repair adhesive for chemical milling is mainly used in conjunction with water-based chemical milling protective adhesive. It has excellent resistance to chemical corrosion and is well-compatible with water-based chemical milling adhesive film substrates. After the chemical milling process is completed, the film is easy to peel off. The peeled surface does not require special treatment before subsequent surface treatment processes. It can dry and cure quickly at room temperature, greatly shortening the working time.

[0003] Currently, domestic repair adhesives are mainly solvent-based and high-solids types, which have poor chemical corrosion resistance and cannot be used for independent chemical milling, seriously affecting their chemical milling performance and construction time. Moreover, the volatile solvents are toxic and carcinogenic, seriously threatening the health of operators, causing serious environmental pollution, and having poor safety. Water-based chemical milling repair adhesives use water as a solvent system and are applied by brushing. They have advantages such as being green and environmentally friendly, capable of independent chemical milling, easy to operate, low paint loss, no dust pollution, and high safety. They can not only meet the molding requirements of complex structures and thin-walled parts, but also match well with the substrate to be milled during the chemical milling process, repairing defects and providing temporary protection. Furthermore, they can be milled independently without issues such as leakage, warping, or edge slippage. The erosion ratio meets the precision requirements for aircraft skin machining. After the chemical milling process, the film is easily distinguishable from the chemical milling adhesive and line sealant, and is easy to peel off. The peeled surface can undergo subsequent surface treatment processes without special treatment. Summary of the Invention

[0004] The purpose of this invention is to provide a water-based repair adhesive applicable to chemical milling, which can be applied by brushing or spraying. It offers advantages such as being environmentally friendly, easy to apply, capable of standalone chemical milling, having good density, and a balance between adhesion and peelability. During chemical milling, it can repair defects and imperfections in the substrate of the water-based chemical milling adhesive film, and dries rapidly at room temperature. Standalone chemical milling ensures that the etching ratio meets the chemical milling process specifications, while maintaining excellent peelability after the chemical milling process is completed.

[0005] This invention provides a water-based repair adhesive that can be used for chemical milling, comprising the following components by weight percentage:

[0006]

[0007] The main base resin mentioned therein is a mixture of one or more of the following in any proportion: waterborne SEBS resin and waterborne liquid petroleum resin, waterborne SIS resin, waterborne SBS emulsion, waterborne acrylic modified polyurethane, waterborne polyurethane emulsion, waterborne acrylic resin, and water-soluble rosin resin.

[0008] The solvent is one or more types of deionized water or tap water.

[0009] The pigment is one or more of the following: water-based red pigment, water-based yellow pigment, water-based fruit green pigment, water-based bright blue pigment, and ultra-black powder.

[0010] The filler is one or more of the following: talc powder (2500 mesh), talc powder (3000 mesh), talc powder (1250 mesh), gas-processed silica (5nm, 10nm, 20nm), and precipitated silica.

[0011] The additives are: substrate wetting and dispersing agent, which is one or more of SN-4741BYK-346, BYK-190, and Tego Twin 4100; defoamer, which is one or more of SN-6792, BYK-093, and BYK-094; foam suppressant, which is 902w; surface additive, which is one or two of BYK-354 and SN-4333; cosolvent, which is one or two of DPM and DPNB; pH adjuster, which is AMP95; and thickener, which is one or more of TT-935, hydroxyethyl cellulose, and bentonite.

[0012] The second aspect provides a method for preparing a water-based repair adhesive that can be used for chemical milling:

[0013] Add all solvents and co-solvents from the additives to the resin dissolving kettle, start stirring at a speed of 600-700 r / min, add all the base material wetting and dispersing agents from the additives and stir evenly, then add all the main base material resin and add the defoamer and defoaming agent after it is completely dissolved. Add filler and pigment in sequence while stirring. All the above raw materials are stirred at high speed at a speed of 750 r / min until they are evenly mixed. Adjust the pH value of the system with a pH adjuster and adjust the viscosity of the system with a thickener. Grind and disperse the mixture with a sand mill until the fineness is ≤30μm, discharge the material, filter and package it as the finished product.

[0014] The beneficial effects of this invention are:

[0015] This invention introduces a waterborne liquid petroleum resin with good initial tack into waterborne SIS resin, giving it adhesion properties that are high at high temperatures and low at low temperatures. It achieves a balance between adhesion and peelability while maintaining good formability. Simultaneously, the introduction of waterborne SEBS resin improves the film's resistance to chemical corrosion, enabling individual chemical milling and ensuring the etching ratio meets the chemical milling process specifications. The introduction of waterborne acrylic-modified polyurethane not only gives the film excellent water resistance and a certain degree of hardness, but the introduction of a co-solvent improves the compatibility between the resins. The combination of fumed silica and talc significantly enhances the mechanical properties of the film. Using water as a solvent is environmentally friendly, avoiding the harm to human health and the environment caused by organic solvents.

[0016] It boasts advantages such as being environmentally friendly, easy to construct, capable of standalone chemical milling, having good density, and balancing adhesion and peelability. During chemical milling, it can repair defects and imperfections in the substrate of the water-based chemical milling film, and quickly dry into a film at room temperature. Standalone chemical milling ensures that the etching ratio meets the chemical milling process specifications, while also exhibiting excellent peelability after the chemical milling process is completed. Detailed Implementation

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Example 1:

[0019] Weigh 38.0g of tap water and 4.0g of DMP into a resin dissolving vessel, start stirring at 600-700 rpm, add the following: stir for 30 minutes, add 0.4g of substrate wetting and dispersing agent BYK-346, and mix thoroughly. Then weigh 17.0g of waterborne SIS resin emulsion, 6.0g of waterborne SBS resin, and 7.0g of waterborne liquid petroleum resin, and add 2.0g of SEBS resin. Stir thoroughly until the resin is completely dissolved. Add 0.2g of defoamer BYK-093, then add 8.0g of talc (2000 mesh), 9.0g of fumed silica (10nm), and 0.04g of water-based red pigment while stirring. Increase the stirring speed to 750r / min and stir for about 30 minutes until homogeneous. Then add 1.5g of thickener hydroxyethyl cellulose and 0.1g of pH adjuster AMP95. Disperse and grind the mixture in a basket mill until the fineness is less than 30μm, and then discharge the material.

[0020] A water-based chemical milling adhesive was applied to a 2A12-T4 aluminum plate that required chemical milling. After it was completely dry, an area approximately half the size of the aluminum plate was etched out. The prepared quick-drying chemical milling repair adhesive was then applied to this area. After the adhesive film dried, the area was etched and chemically milled, and performance tests were conducted. The test performance results are shown in Table 1 below.

[0021] Table 1: Test Results of Example 1

[0022]

[0023] Example 2:

[0024] Weigh 40.0g of tap water and 4.5g of DMP into a resin dissolving kettle, turn on the stirrer at 600-700 rpm, add 0.6g of substrate wetting and dispersing agent BYK-190, stir for 30 minutes until homogeneous, then weigh 20g of waterborne polyurethane emulsion, 6.0g of waterborne liquid petroleum resin, then add 2.3g of SEBS resin and 6.4g of water-soluble rosin resin, stir thoroughly until the resin is completely dissolved, then add 0.3g of defoamer BYK-094, and while stirring, add 9.4g of talc powder (3000 mesh), 10.8g of fumed silica (20nm), and 0.06g of waterborne yellow pigment. Increase the stirring speed to 750 rpm and stir for about 30 minutes until homogeneous, then add 0.15g of pH adjuster AMP95 and 3g of thickener bentonite, and then add to a basket mill for dispersion and grinding until the fineness is less than 30μm, and then discharge the material.

[0025] A water-based chemical milling adhesive was applied to a 2A12-T4 aluminum plate that required chemical milling. After it was completely dry, an area approximately half the size of the aluminum plate was etched out. The prepared quick-drying chemical milling repair adhesive was then applied to this area. After the adhesive film dried, the area was etched and chemically milled, and performance tests were conducted. The test performance results are shown in Table 2 below.

[0026] Table 2: Test Results of Example 2

[0027]

[0028] Example 3:

[0029] Weigh 45.0g of deionized water and 5.0g of DPNB into a resin dissolving kettle, start stirring at 600-700 rpm, add 0.7g of substrate wetting and dispersing agent Tego Twin4100, stir for 30 minutes until homogeneous, then weigh 25.0g of waterborne acrylic modified polyurethane emulsion, 5.8g of waterborne liquid petroleum resin, then add 3.0g of SEBS resin and 6.0g of waterborne SBS resin, stir thoroughly until the resin is completely dissolved, then add 0.4g of defoamer SN-6792, and while stirring, add 10.0g of talc (1250 mesh), 9.0g of fumed silica (5nm), and 0.07g of waterborne fruit green pigment. Increase the stirring speed to 750 rpm and stir for about 30 minutes until homogeneous, then add 0.3g of pH adjuster AMP95 and 0.6g of thickener TT-935, and then add to a basket mill for dispersion and grinding until the fineness is less than 30μm, then discharge.

[0030] A water-based chemical milling adhesive was applied to a 2A12-T4 aluminum plate that required chemical milling. After it was completely dry, an area approximately half the size of the aluminum plate was etched out. The prepared quick-drying chemical milling repair adhesive was then applied to this area. After the adhesive film dried, the area was etched and chemically milled, and performance tests were conducted. The test performance results are shown in Table 3 below.

[0031] Table 3: Test Results of Example 3

[0032]

[0033] This disclosure has been described with reference to the foregoing embodiments; however, these embodiments are merely examples for implementing this disclosure. It must be noted that the disclosed embodiments do not limit the scope of this disclosure. On the contrary, any changes and modifications made without departing from the spirit and scope of this disclosure are within the scope of patent protection of this disclosure.

Claims

1. An aqueous patching adhesive useful for chemical milling, characterized in that: By weight parts, consisting of the following components: Main base resin 30~45% Filler 15~20% Pigment 0.03~0.08% Auxiliary agent 3~9% Solvent 35~50%, Wherein the main base resin is a mixture of water-based SEBS resin and water-based liquid petroleum resin with water-based SIS resin, water-based SBS emulsion, water-based acrylic modified polyurethane, water-based polyurethane emulsion, water-based acrylic resin, water-soluble rosin resin in any proportion; The filler is 2500 mesh talc, 3000 mesh talc, 1250 mesh talc, 5nm fumed silica, 10nm fumed silica, 20nm fumed silica, precipitated silica one or several; The solvent is deionized water or tap water; The auxiliary agent is: base material wetting dispersant is one or several of SN-4741 BYK-346, BYK-190, Tego Twin 4100; Defoaming agent is one or several of SN-6792, BYK-093, BYK-094; Foam inhibitor is 902w; Co-solvent is one or two of DPM and DPNB; PH regulator is AMP95; Thickening agent is one or several of TT-935, hydroxyethyl cellulose and bentonite; The water-based repair glue for chemical milling is prepared by the following steps: adding all the solvents and co-solvents in the auxiliary agent into the resin dissolving kettle, starting stirring, stirring speed is 600~700r / min, adding all the base material wetting dispersant in the auxiliary agent, stirring uniformly, then adding the main base resin, adding defoaming agent and foam inhibitor after complete dissolution, adding filler and pigment in turn under stirring, stirring each raw material by high speed stirring, stirring speed is 750r / min, stirring uniformly, adjusting the PH value of the system with PH regulator, adjusting the viscosity of the system with thickening agent, grinding and dispersing to fineness≤30μm with sand mill, discharging, filtering and packaging as finished product.

2. The aqueous repair compound for chemical milling according to claim 1, characterized in that: The pigment is one or several of water-based red pigment, water-based yellow pigment, water-based fruit green pigment, water-based bright blue pigment and special black powder.

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