Novel chemical milling protective strippable coating and preparation method thereof

Abstract

The invention discloses a novel chemical milling protective strippable coating, which is composed of 8.0-12% of SEEPS resin, 2-8% of SEPS resin, 4-6% of hydrogenated petroleum resin, 15-18% of filler, 0.01-0.05% of pigment, 1-5% of assistant and 51-60% of solvent, SEPS and SEEPS thermoplastic elastomer are used as main body base resin, and SEPS has short methyl unit series, so that SEPS cannot crystallize, is softer than crystalline SEBS thermoplastic elastomer, and has better chemical milling protection performance. The SEPS has a short methyl unit series, so that the SEPS cannot crystallize and is softer than a crystallized SEBS thermoplastic elastomer, and the elasticity and hysteresis behavior of the SEPS are better than those of the SEBS. Meanwhile, the SEEPS resin which is low in viscosity, high in tensile strength and low in permanent deformation and has SEBS and SEPS properties is introduced into the formula, so that the problems of serious coating loss and low construction efficiency caused by poor defoaming and low solid content of a chemical milling protection strippable coating product under the condition of optimal construction viscosity, and the problems of substrate leakage corrosion, serious paint film warping and poor corrosion resistance during high-temperature deep chemical milling processing are solved. The problem that the etching ratio is large due to the fact that the milling cutting edge of the chemical milling base material moves upwards and a two-step phenomenon is generated is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of chemical milling coatings, and in particular relates to a novel chemical milling protective strippable coating and a preparation method thereof. Background Art

[0002] Chemical milling protective strippable coating is an indispensable and important material in the process of chemical milling (abbreviated as chemical milling). It is widely used in the temporary protection of different metal substrates such as aluminum alloy and titanium alloy in the aviation industry during chemical milling due to its simple operation, low coating loss and various construction methods. It can also be extended to the anti-chemical corrosion masking protection of the coated surface, or used as a temporary protection for instruments, meters, equipment, etc. to prevent scratches and abrasions during storage, transportation and use. It has broad application prospects.

[0003] At present, the main base resins of chemical milling protection strippable coatings in China are SIS (styrene-isoprene-styrene block copolymer), SBS (styrene-butadiene-styrene block copolymer) and SEBS (styrene-ethylene-butylene-styrene block copolymer) thermoplastic elastomers. Chemical milling protection strippable coatings, represented by SIS and SBS thermoplastic elastomers, have serious deficiencies in heat resistance and aging resistance due to the presence of multiple unsaturated double bonds in their structures. The adhesion to aluminum alloy materials is unstable. After film formation, the adhesion increases significantly with the extension of time. It is difficult to remove the coating before and after chemical milling, and it cannot meet the use requirements during chemical milling. Although chemical milling protection peelable coating products represented by SEBS thermoplastic elastomer have excellent heat resistance, weather resistance and aging resistance, during the high-temperature deep chemical milling process, a large number of bubbles are generated in the reaction between the substrate and the chemical milling liquid. The bubbles scour the paint film for a long time, causing the paint film to curl severely, resulting in the upward movement of the milling edge of the chemical milling substrate and the two-step phenomenon, which makes the etch ratio too large and cannot meet the technical requirements of the parts in the deep chemical milling process, seriously affecting the quality of the chemical milling products and causing the parts to be scrapped. Among them, chemical milling protection peelable coating products represented by high molecular weight SEBS thermoplastic elastomers have poor defoaming under the optimal construction viscosity conditions and low solid content. The following problems currently exist:

[0004] 1) During construction, multiple times (spraying / brushing / dipping) are required to achieve the thickness requirements of the paint film for chemical milling, resulting in serious paint loss and low construction efficiency;

[0005] 2) After construction, a large number of bubbles cannot be removed, the paint film has poor density after drying, and the base material will be corroded during the deep milling process of alkali solution.

[0006] Although new chemical milling protective strippable coating products represented by low molecular weight SEBS thermoplastic elastomers can solve the problems of poor defoaming and low solid content, compared with chemical milling protective strippable coating products represented by high molecular weight SEBS thermoplastic elastomers, the problem of paint film curling during high-temperature deep chemical milling is more serious. Summary of the invention

[0007] The purpose of the present invention is to provide a novel chemical milling protective peelable coating which has good defoaming property and high solid content under the condition of optimal construction viscosity, and at the same time, in the process of high-temperature deep chemical milling, bubbles can flush the paint film for a long time, which will not cause the milling edge of the chemical milling substrate to move up and produce a two-step phenomenon, and the etching ratio meets the technical requirements of parts in deep chemical milling processing, so as to solve the technical defects of new chemical milling protective peelable coating products represented by SEBS thermoplastic elastomer, such as serious coating loss during construction, low construction efficiency, leakage of substrate during high-temperature deep chemical milling, and the production of two-step problems resulting in a large etching ratio.

[0008] The invention discloses a novel chemical milling protective strippable coating, which is composed of the following components by mass percentage:

[0009]

[0010] The molecular weight of the SEEPS (styrene-ethylene-ethylene-propylene-styrene block copolymer) resin is one or more of 80,000 to 120,000.

[0011] The molecular weight of the SEPS (styrene-ethylene-propylene-styrene block copolymer) resin is one or more of 50,000 to 100,000.

[0012] The hydrogenated petroleum resin is hydrogenated C5 petroleum resin, and the molecular weight is one or more of 200 to 5000.

[0013] The solvent is one or more of solvents such as benzene and tetrachloroethylene.

[0014] The pigment is one or more of lemon yellow and phthalocyanine green.

[0015] The filler is one or more of talc, kaolin, sericite and fumed silica.

[0016] The auxiliary agent is one or more of a wetting and dispersing agent, a defoaming agent and a leveling agent.

[0017] The invention also discloses a preparation method of a novel chemical milling protective peelable coating, comprising the following steps: dissolving SEEPS resin, SEPS resin and hydrogenated petroleum resin in a solvent according to a proportion, adding fillers and pigments after they are completely dissolved, and adding additives in sequence under stirring, stirring the above raw materials evenly with a high-speed stirrer, grinding and dispersing them with a sand mill to a fineness of ≤40μm, filtering and packaging to obtain the novel chemical milling protective peelable coating.

[0018] Beneficial Effects

[0019] The main base resin in the novel chemical milling protection strippable coating prepared by the present invention is mainly based on SEPS and SEEPS thermoplastic elastomers. SEPS has a shorter methyl unit series, so it will not crystallize, and is softer than the crystallized SEBS thermoplastic elastomer. The elasticity and hysteresis behavior of SEPS are better than SEBS. At the same time, SEEPS resin with low viscosity, high tensile strength, low permanent deformation, and both SEBS and SEPS performance is introduced into the formula to solve the problems of poor defoaming of chemical milling protection strippable coating products under the best construction viscosity conditions, serious coating loss caused by low solid content, low construction efficiency, and leakage of the base material during high-temperature deep chemical milling processing, serious curling of the paint film, and upward movement of the milling cutting edge of the chemical milling substrate, resulting in a two-step phenomenon, thereby causing a large etch ratio. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Embodiment 1:

[0022] Preparation of a new type of chemical milling protective strippable coating

[0023] Weigh 10g SEEPS resin, 5g SEPS resin and 5g C5 hydrogenated petroleum resin, add 10g toluene, 30g xylene and 10g tetrachloroethylene, use a high-speed mixer to stir evenly until completely dissolved, then add 0.02g lemon yellow, 6.0g talcum powder, 9.0g gas silica, after complete dissolution, add 1g wetting dispersant, 0.5g defoaming agent, 0.7g leveling agent, mix evenly and grind in a grinding and dispersing machine until the fineness is less than 40μm to make a new type of chemical milling protective strippable coating.

[0024] Performance Testing

[0025] Apply the new chemical milling protective peelable coating on the 2A12-T4 aluminum plate that needs chemical milling. After drying for 18 hours, carry out the engraving chemical milling test.

[0026] The test performance results are as follows:

[0027]

[0028] Example 2

[0029] Preparation of a new type of chemical milling protective strippable coating

[0030] Weigh 12g SEEPS resin, 6g SEPS resin and 6g C5 hydrogenated petroleum resin, add 15g toluene, 35g xylene and 10g tetrachloroethylene, use a high-speed mixer to stir evenly until completely dissolved, then add 0.02g lemon yellow, 6.0g talcum powder, 10.0g gas silica, after complete dissolution, add 0.8g wetting dispersant, 0.7g defoaming agent, 0.6g leveling agent, mix evenly and grind in a grinding and dispersing machine until the fineness is less than 40μm to make a new type of chemical milling protective strippable coating.

[0031] Performance Testing

[0032] Apply the new chemical milling protective peelable coating on the 2A12-T4 aluminum plate that needs chemical milling. After drying for 18 hours, carry out the engraving chemical milling test.

[0033] The test performance results are as follows:

[0034]

[0035]

[0036] The present disclosure has been described by the above-mentioned relevant embodiments, but the above-mentioned embodiments are only examples for implementing the present disclosure. It must be pointed out that the disclosed embodiments do not limit the scope of the present disclosure. On the contrary, changes and modifications made without departing from the spirit and scope of the present disclosure are all within the scope of patent protection of the present disclosure.

Claims

1. A new type of chemical milling protective strippable coating, characterized in that: Calculated by mass percentage, it is composed of the following components:

2. The novel chemical milling protective strippable coating according to claim 1 is characterized in that: The SEEPS resin has a molecular weight of 80,000 to 120,000.

3. The novel chemical milling protective strippable coating according to claim 1 is characterized in that: The SEPS resin has a molecular weight of 50,000 to 100,000.

4. The novel chemical milling protective strippable coating according to claim 1 is characterized in that: The hydrogenated petroleum resin is hydrogenated C5 petroleum resin, and the molecular weight is one or more of 200 to 5000.

5. The novel chemical milling protective strippable coating according to claim 1 is characterized in that: The pigment is one or more of lemon yellow and phthalocyanine green.

6. The novel chemical milling protective strippable coating according to claim 1 is characterized in that: The filler is one or more of talc, kaolin, sericite and fumed silica.

7. The novel chemical milling protective strippable coating according to claim 1 is characterized in that: The solvent is one or more of benzene and tetrachloroethylene solvents.

8. The novel chemical milling protective strippable coating according to claim 1 is characterized in that: The auxiliary agent is one or more of a wetting and dispersing agent, a defoaming agent and a leveling agent.

9. A method for preparing the novel chemical milling protective strippable coating according to any one of claims 1 to 8, characterized in that: The following steps are involved: Dissolve SEEPS resin, SEPS resin and hydrogenated petroleum resin in solvent according to the proportion, add fillers and pigments after they are completely dissolved, and add additives in sequence under stirring. After the above raw materials are evenly stirred with a high-speed mixer, they are ground and dispersed with a sand mill to a fineness of ≤40μm, and filtered and packaged to obtain a new type of chemical milling protective strippable coating.

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