Two-component chemical milling protective coating and method for producing same

Abstract

The application discloses a two-component chemical milling protective paint, which is composed of component one and component two in a mass ratio of 1.3-1.5:1; the component one is composed of diphenyl methane diisocyanate, toluene diisocyanate, hexamethylene diisocyanate and polyether glycol; and the component two is composed of polyaspartic ester, an auxiliary agent and a pigment and filler. The prepared two-component chemical milling protective paint not only realizes that the theoretical non-volatile content reaches 100%, and one-time spraying can reach 400 micrometers, is not sensitive to humidity (can be normally used when humidity is greater than or equal to 70%), can be soaked in hot alkali for a long time without being damaged, and meets the requirements of temporary protection of aluminum, titanium and other metals in the chemical milling process.

Description

Technical Field

[0001] This invention relates to the field of chemical milling protective coatings, specifically a two-component chemical milling protective coating and its preparation method. Background Technology

[0002] Chemical milling (CCM) is a technique that relies on the controlled and uniform corrosion of metallic materials using chemical solutions. It utilizes chemical etching to process workpieces and offers the following advantages compared to conventional machining methods:

[0003] 1) Advanced and controllable chemical milling technology can meet the general weight reduction and machining accuracy requirements of hyperboloid outer skin and stealth sawtooth structure, and the weight reduction ratio can reach 30%-70%.

[0004] 2) Chemical milling does not generate cutting stress, thus meeting the requirements for assembly accuracy and fatigue performance;

[0005] 3) Multiple parts can be processed at once, and both sides can be processed simultaneously, improving production efficiency;

[0006] 4) Highly adaptable; for newly designed or prototype parts, chemical milling can be used to quickly complete the machining process.

[0007] Chemical milling protective coatings are primarily temporary protective coatings applied during the chemical milling process. They provide temporary protection during machining and are removed after the chemical milling is completed. They are mainly used for chemical milling of aluminum alloys and titanium alloys; machining of high-hardness metals; temporary protection during anodizing and electroplating of aluminum alloys; and etching of complex artworks. They can also be used for chemical corrosion masking of surfaces, or for temporary protection of instrument surfaces and machinery against scratches and abrasions.

[0008] Existing chemical milling protective coatings often use non-environmentally friendly organic solvents such as toluene and xylene as diluents. These coatings are costly, have a strong odor, and require drying times of up to 24 hours. In high-humidity environments (humidity ≥ 70%), the coating surface easily absorbs moisture, which not only affects the performance of the product but also extends the drying time to more than 30 hours, seriously impacting the production efficiency of aerospace companies. Furthermore, long-term use can cause serious damage to the organs of the workers, and the high VOC emissions cause severe environmental damage. Summary of the Invention

[0009] The purpose of this invention is to provide a two-component chemical milling protective colloid that not only achieves a theoretical non-volatile content of 100%, but also allows for a single spray coating thickness of up to 400 μm, and is insensitive to humidity (it can be used normally at humidity ≥70%), thus meeting the requirements for temporary protection of aluminum, titanium, and other metals during chemical milling processes. The objective of this invention is to prepare a 100% solids-content two-component chemical milling protective coating that can withstand prolonged immersion in hot alkaline solutions without degradation, and meets all the requirements of existing chemical milling processes.

[0010] The technical solution of the present invention is: a two-component chemical milling protective coating, which is composed of component one and component two in a mass ratio of 1.3-1.5:1;

[0011] By mass percentage, component one consists of the following components:

[0012]

[0013] Component two is composed of the following components:

[0014] Polyaspartic acid ester 61%–65%

[0015] Additives 3%–4%

[0016] Pigments and fillers: 31%–35%.

[0017] Furthermore, the diphenylmethane diisocyanate is one or more of 4,4'-diphenylmethane diisocyanate, MDI-50, and 2,4'-diphenylmethane diisocyanate.

[0018] Furthermore, the toluene diisocyanate is one or both of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate.

[0019] Furthermore, the polyether diol is one or both of polyether 210 and polyether 220.

[0020] Furthermore, the polyaspartic ester is one or more of JH-8125, NH-Q230, and LB-852A.

[0021] Furthermore, the filler is one or two of barium metaborate, sericite, and kaolin.

[0022] Furthermore, the additive is two or more of BYK-103, BYK-066N, BYK-163, and BYK-430.

[0023] A two-component chemical milling protective coating preparation method includes the following steps:

[0024] Preparation of Component 1: Diphenylmethane diisocyanate, toluene diisocyanate, and hexamethylene diisocyanate were added to a four-necked flask, a reflux condenser was assembled, and an oil bath was turned on to heat the mixture to 50°C. The mixture was stirred at 500 rpm until the isocyanates were completely dissolved. Then the temperature was raised to 110°C, and polyether diol was added dropwise using a dropping funnel. The addition was completed in 2.5 hours. The -NCO content was measured to be between 9% and 13%. The mixture was then cooled and discharged to obtain Component 1.

[0025] Preparation of Component 2: Polyaspartic acid ester was added to a four-necked flask and heated to 70℃-80℃. Under stirring at 700r / min, pigments and fillers were added and stirred for 40 minutes. Then, the additives were added and stirred for another 20 minutes. The mixture was cooled and discharged to obtain Component 2.

[0026] A two-component chemical milling protective coating is obtained by mixing component one and component two in a mass ratio of 1.3-1.5:1.

[0027] The beneficial effects of this invention are:

[0028] This invention relates to a two-component chemical milling protective coating, which is synthesized from isocyanate and polyether polyol to form an isocyanate prepolymer, which is then reacted with polyaspartic acid ester resin to form a novel elastomer material. The material theoretically has a 100% non-volatile content, can achieve a coating thickness of 400 μm in a single spray, is insensitive to humidity (can be used normally at humidity ≥70%), exhibits suitable peel strength on aluminum and titanium alloys, and possesses good acid and alkali resistance. Its performance meets the application requirements of chemical milling processes. Detailed Implementation

[0029] 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.

[0030] Example 1:

[0031] Component 1:

[0032] 32g of MDI-50, 3g of 2,4-toluene diisocyanate, and 10g of hexamethylene diisocyanate were added to a four-necked flask. A reflux condenser was assembled, and an oil bath was turned on to heat the mixture to 50°C. The mixture was stirred at a medium speed (500r / min) until the materials were completely dissolved. The temperature was then raised to 110°C, and 52g of polyether diol N-210 was added dropwise using a dropping funnel. The addition was completed in 2.5 hours. The -NCO content was measured to be between 10.6%. The mixture was then cooled and discharged to obtain component one.

[0033] Component 2:

[0034] 40g of polyaspartic acid ester JH-8125 was added to a four-necked flask and heated to 70℃-80℃. While stirring, 8g of barium metaborate and 13g of kaolin were added. After stirring at medium speed (700r / min) for 40min, 0.9g of BYK-103, 0.6g of BYK-066N, and 0.6g of BYK-430 were added, and stirring continued for 20min. The mixture was then cooled and discharged to obtain component two.

[0035] Component 1 and Component 2 were mixed at a mass ratio of 1.3:1 and applied to the pre-treated aluminum alloy using a specialized spraying equipment. After the coating was fully cured, the performance was tested as follows:

[0036] Serial Number project Test Results 1 Dry at room temperature for 6 hours Completely dry 2 Peel strength, N / m 165～228 2 Soak in hot alkaline solution (100℃) for 8 hours No bubbling, bulging, or leakage. 3 Immerse in acid solution (at room temperature) for 4 hours No bubbling, bulging, or leakage. 4 Adhesion, after soaking in hot alkaline solution (98℃) for 8 hours It does not peel off from the chemical milling film.

[0037] Example 2:

[0038] Component 1:

[0039] 25g of MDI-50, 10g of 4,4'-diphenylmethane diisocyanate, 3g of 2,4'-toluene diisocyanate, 2g of 2,6'-toluene diisocyanate, and 8.6g of hexamethylene diisocyanate were added to a four-necked flask. A reflux condenser was assembled, and an oil bath was turned on to heat the mixture to 50°C. The mixture was stirred at medium speed (500 rpm) until all the materials were completely dissolved. Then, the temperature was raised to 110°C, and 55g of polyether diol N-220 was added dropwise using a dropping funnel over 2.5 hours. The -NCO content was measured to be 9.4%. The mixture was then cooled and discharged to obtain component one.

[0040] Component 2:

[0041] 39g of polyaspartic acid ester NH-Q230 was added to a four-necked flask and heated to between 70℃ and 80℃. While stirring, 10g of barium metaborate and 12g of sericite were added. The mixture was stirred at medium speed (700 rpm) for 40 minutes, then 1g of BYK-163 and 1.5g of BYK-066N were added, and stirring continued for another 20 minutes. The mixture was then cooled and discharged to obtain component two.

[0042] Component 1 and Component 2 were mixed at a mass ratio of 1.5:1 and applied to the pre-treated aluminum alloy using a specialized spraying equipment. After the coating was fully cured, the performance was tested as follows:

[0043] Serial Number project Test Results 1 Dry at room temperature for 6 hours Completely dry 2 Peel strength, N / m 116～138 2 Soak in hot alkaline solution (103℃) for 8 hours No bubbling, bulging, or leakage. 3 Immerse in acid solution (at room temperature) for 4 hours No bubbling, bulging, or leakage. 4 Adhesion, after soaking in hot alkaline solution (95℃) for 8 hours It does not peel off from the chemical milling film.

[0044] 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. A two-component chemical milling protective coating, characterized in that: It is composed of component one and component two in a mass ratio of 1.3-1.5:1; By mass percentage, component one consists of the following components: Diphenylmethane diisocyanate 31%~36% Toluene diisocyanate 3%~6% Hexamethylene diisocyanate 8%~12% Polyether diol 50%~55%; Component two is composed of the following components: Polyaspartic acid ester 61%~65% Additives 3%~4% Pigments and fillers 31%~35%; The diphenylmethane diisocyanate is one or more of 4,4'-diphenylmethane diisocyanate, MDI-50, and 2,4'-diphenylmethane diisocyanate; the toluene diisocyanate is one or two of 2,4'-toluene diisocyanate and 2,6'-toluene diisocyanate; and the polyether diol is one or two of polyether 210 and polyether 220. The two-component chemical milling protective coating is prepared by the following steps: Preparation of Component 1: Diphenylmethane diisocyanate, toluene diisocyanate, and hexamethylene diisocyanate were added to a four-necked flask, a reflux condenser was assembled, and an oil bath was turned on to heat the mixture to 50°C. The mixture was stirred at 500 r / min until the isocyanates were completely dissolved. Then the temperature was raised to 110°C, and polyether diol was added dropwise using a dropping funnel. The addition was completed in 2.5 hours. The -NCO content was measured to be between 9% and 13%. The mixture was then cooled and discharged to obtain Component 1. Preparation of Component 2: Polyaspartic acid ester was added to a four-necked flask and heated to 70℃-80℃. Under stirring at 700r / min, pigments and fillers were added and stirred for 40 minutes. Then, the additives were added and stirred for another 20 minutes. The mixture was cooled and discharged to obtain Component 2. A two-component chemical milling protective coating is obtained by mixing component one and component two in a mass ratio of 1.3-1.5:

1.

2. The two-component chemical milling protective coating according to claim 1, characterized in that: The polyaspartic ester is one or more of JH-8125, NH-Q230, and LB-852A.

3. The two-component chemical milling protective coating according to claim 1, characterized in that: The pigments and fillers are one or two of barium metaborate, sericite, and kaolin.

4. The two-component chemical milling protective coating according to claim 1, characterized in that: The additives are multiples of BYK-103, BYK-066N, BYK-163, and BYK-430.

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