A nano-injection-based stainless steel workpiece and a surface treatment method thereof

Abstract

This invention discloses a stainless steel workpiece based on nano-injection molding and its surface treatment method, belonging to the field of metal material processing technology. The invention first performs alkaline washing and acid washing on the stainless steel surface, then impregnates it with an activating solution and a film-forming agent to form nanoscale pores on the stainless steel surface. Finally, a layer of resin containing chitosan-modified silica is coated to enhance the bonding strength between the stainless steel and the plastic. The addition of silica can enhance the bonding strength between stainless steel and plastic. This invention first prepares a wrinkled silica with a large specific surface area, and then further modifies it with vinyl chitosan. The surface of the wrinkled silica can be loaded with a large amount of vinyl chitosan.

Description

Technical Field

[0001] This invention relates to the field of metal material processing technology, specifically to a stainless steel workpiece based on nano-injection molding and its surface treatment method. Background Technology

[0002] There are various surface treatment methods for stainless steel workpieces. Traditional surface treatments often employ electroplating and spraying, but these methods suffer from drawbacks such as easy peeling, poor adhesion, and insufficient acid and alkali resistance. Nano-injection molding technology first nano-scales the metal surface, creating micron or nano-sized pores on the stainless steel surface, and then directly injects plastic into the metal, achieving integration between the metal and plastic. Compared to traditional bonding techniques, nano-injection molding offers higher strength and processing efficiency. However, existing nano-injection molding technologies still have shortcomings in improving the bonding strength between stainless steel and plastic. The bonding strength between the stainless steel substrate and plastic after some treatments is relatively low, making it difficult to meet the high requirements of industrial applications.

[0003] To address the aforementioned problems and improve the bonding strength between plastic and stainless steel, this invention provides a stainless steel workpiece based on nano-injection molding and its surface treatment method. Summary of the Invention

[0004] The purpose of this invention is to provide a stainless steel workpiece based on nano-injection molding and its surface treatment method, so as to solve the problems raised in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A surface treatment method for stainless steel workpieces based on nano-injection molding includes the following steps:

[0007] Step 1: Take stainless steel, wash and dry it with water, immerse it in an alkaline treatment solution for 3-5 minutes, wash and dry it with water; take it out, then immerse it in an acid treatment solution for 10-12 minutes, wash and dry it with water; take it out, immerse it in an activation solution for 10-12 minutes, wash and dry it with water; take it out, then immerse it in a film-forming agent for 10-12 minutes, wash and dry it with water to obtain the treated stainless steel substrate;

[0008] Step 2: Apply coating A evenly to the surface of the treated stainless steel substrate and cure it with ultraviolet light to obtain a surface-treated stainless steel substrate.

[0009] In a more optimized manner, the preparation method of coating A is as follows: take chitosan-modified silica and methyl ethyl ketone, stir evenly, add 37g of epoxy curing agent, mix evenly, add pyrrole, branched epoxy resin and acetone, mix evenly to obtain coating A.

[0010] More preferably, the alkaline treatment solution uses deionized water as a solvent and is composed of the following components: 15-25 g / L sodium hydroxide, 12-17 g / L sodium carbonate, and 2-2.5 g / L OP-10 emulsifier;

[0011] The acid treatment solution uses deionized water as a solvent and consists of the following components: phosphoric acid, with a concentration of 20%-40%;

[0012] The activation solution uses deionized water as a solvent and consists of the following components: 17-22 g / L sodium peroxide, 9-13 g / L ammonium bifluoride, 7-10 g / L glycerol, 2-4 g / L acetic acid, and 2-3 g / L boric acid.

[0013] The film-forming agent uses deionized water as a solvent and consists of the following components: 17-20 g / L citric acid, 12-17 g / L sodium thiosulfate, and 10-15 g / L sodium dihydrogen borate.

[0014] A more optimized method for preparing the chitosan-modified silica includes the following steps:

[0015] S1: Take chitosan, formaldehyde, and acetic acid, mix them evenly, add acrolein after 1-2 hours, heat to 50-55℃, stir for 8-12 hours, filter, wash, and dry to obtain vinyl chitosan.

[0016] S2: Take glacial acetic acid aqueous solution and vinyl chitosan, stir evenly to obtain chitosan acetic acid solution; take 3-glycidyl ether trimethoxysilane and chitosan acetic acid solution and stir for 12-14h, add wrinkled silica, stir for 10-12h, centrifuge, wash and dry to obtain chitosan modified silica.

[0017] A more optimized method for preparing the wrinkled silica is as follows: take hexadecyltrimethylammonium bromide, urea, and deionized water, stir evenly, add butanol and cyclohexane, and stir for 30-40 min; add tetraethyl orthosilicate dropwise, stir for 30-40 min, then heat to 70-75℃, stir for 22-26 h, centrifuge, dry, and then calcine at 550-555℃ to obtain wrinkled silica.

[0018] In a more optimized manner, a surface-treated stainless steel substrate is taken, reacted at 120-150℃ for 5-10 minutes, and then nano-injection molded using a polyamide mixture at a pressure of 110-130MPa, followed by annealing to obtain a stainless steel workpiece based on nano-injection molding.

[0019] More preferably, the polyamide mixture includes thiolized polyamide and polyamide; the mass ratio of thiolized polyamide to polyamide is 1:(1-1.2).

[0020] A more optimized method for preparing the thiolized polyamide is as follows: take hyperbranched polyamide and epichlorohydrin, mix them evenly, react at 50-55℃ for 2-3 hours, then ripen at 30℃, add thiourea, heat to 80-82℃ and react for 22-26 hours, purify and dry to obtain thiolized polyamide.

[0021] A more optimized method for preparing the hyperbranched polyamide is as follows: take pyromellitic chloroformyl chloride, lithium chloride, and N,N-dimethylacetamide, stir for 30-40 min, add pyridine and ethylenediamine under ice bath conditions, stir for 2-3 h, raise the temperature to 35-40℃, and react for 12-16 h to obtain the hyperbranched polyamide.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. The present invention first performs alkaline washing and acid washing on the stainless steel surface, and then uses an activating liquid and a film-forming agent to impregnate the stainless steel surface to form nanoscale pores. Then, a layer of resin containing chitosan-modified silica is coated to enhance the bonding strength between stainless steel and plastic.

[0024] 2. The addition of silica can enhance the bonding strength between stainless steel and plastic. This invention first prepares a wrinkled silica with a large specific surface area, and then further modifies it using vinyl chitosan. The surface of the wrinkled silica can be loaded with a large amount of vinyl chitosan.

[0025] 3. Polyamides possess advantages such as high strength, good wear resistance, good chemical stability, and ease of processing, making them an excellent injection molding material. This invention uses a polyamide blend for injection molding, comprising mercapto-modified polyamide and polyamide. Mercapto groups have strong hydrophobicity; mercapto-modified polyamides can reduce moisture penetration and improve the material's stability in humid and hot environments. Furthermore, the mercapto groups in the polyamide blend of this invention can react with the vinyl groups on silica, further enhancing the bonding strength between stainless steel and plastic. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] The sources and types of substances involved in this invention are not specifically limited. Exemplary examples include: epoxy curing agent: type: SM2041, which can be purchased from Guodu Chemical; epoxy resin: type: E44, which can be purchased from Hebei Hongda Environmental Protection Technology Co., Ltd.; silica: particle size: 200nm, which can be purchased from Merck; polyamide: type: FG70G30HSR2 BK309, which can be purchased from Shenzhen Yuanbang New Materials Co., Ltd.; stainless steel: 316L stainless steel.

[0028] Example 1: A stainless steel workpiece based on nano-injection molding, the preparation method of which includes the following steps:

[0029] Step 1:

[0030] S1: Take stainless steel, wash and dry it with water, immerse it in an alkaline treatment solution for 4 minutes, wash and dry it with water; take it out, then immerse it in an acid treatment solution for 11 minutes, wash and dry it with water; take it out, immerse it in an activation solution for 11 minutes, wash and dry it with water; take it out, then immerse it in a film-forming agent for 11 minutes, wash and dry it with water to obtain the treated stainless steel substrate.

[0031] S2: A 100µm thick coating A is uniformly applied to the surface of the treated stainless steel substrate and cured with ultraviolet light to obtain a surface-treated stainless steel substrate.

[0032] S3: Take a surface-treated stainless steel substrate, react it at 140℃ for 8 minutes, use polyamide mixture for nano-injection molding at a pressure of 120MPa, anneal it, and obtain a stainless steel workpiece based on nano-injection molding.

[0033] The polyamide mixture includes thiolized polyamide and polyamide; the mass ratio of thiolized polyamide to polyamide is 1:1.1.

[0034] The alkaline treatment solution uses deionized water as a solvent and consists of the following components: 20 g / L sodium hydroxide, 15 g / L sodium carbonate, and 2.3 g / L OP-10 emulsifier.

[0035] The acid treatment solution uses deionized water as a solvent and consists of the following components: phosphoric acid, with a concentration of 30%;

[0036] The activation solution uses deionized water as a solvent and consists of the following components: 20 g / L sodium peroxide, 11 g / L ammonium hydrogen fluoride, 8 g / L glycerol, 3 g / L acetic acid, and 2.5 g / L boric acid.

[0037] The film-forming agent uses deionized water as a solvent and consists of the following components: 18 g / L citric acid, 15 g / L sodium thiosulfate, and 12 g / L sodium dihydrogen borate.

[0038] Step 2: Preparation of chitosan-modified silica:

[0039] S1: Preparation of wrinkled silica:

[0040] Take 6g of cetyltrimethylammonium bromide, 3.5g of urea, and 200mL of deionized water, stir well, add 8mL of butanol and 150mL of cyclohexane, and stir for 35min; add 22mL of tetraethyl orthosilicate, stir for 35min, then heat to 72℃, stir for 24h, centrifuge, dry, and then calcine at 552℃ to obtain wrinkled silica;

[0041] S2: Preparation of vinyl chitosan:

[0042] Take 10g chitosan, 50g formaldehyde, and 22g acetic acid, mix them evenly, add 20g acrolein after 1.5h, heat to 53℃, stir for 10h, filter, wash, and dry to obtain vinyl chitosan.

[0043] S3: Preparation of chitosan-modified silica:

[0044] Take a 2% (w / w) aqueous solution of glacial acetic acid and vinyl chitosan, stir evenly to obtain a 0.5% (w / w) chitosan acetic acid solution; take 5 mL of 3-glycidyl ether trimethoxysilane and 100 mL of chitosan acetic acid solution and stir for 13 h, add 1 g of wrinkled silica, stir for 11 h, centrifuge, wash and dry to obtain chitosan modified silica;

[0045] Step 3: Preparation of thiolized polyamide:

[0046] S1: Take 2g of pyromellitic methyl chloride, 0.2g of lithium chloride, and 20mL of N,N-dimethylacetamide, stir for 35min, add 0.4mL of pyridine and 0.2g of ethylenediamine under ice bath conditions, stir for 2.5h, raise the temperature to 38℃, and react for 14h to obtain hyperbranched polyamide;

[0047] S2: Take 25g of hyperbranched polyamide and 13g of epichlorohydrin, mix them evenly, react at 53℃ for 2.5h, then ripen at 30℃, add 12g of thiourea, heat to 81℃ and react for 24h, purify and dry to obtain thiolized polyamide.

[0048] Step 4: Preparation of Coating A:

[0049] Take 5g of chitosan-modified silica and 10mL of butanone, stir well, add 37g of epoxy curing agent, mix well, add 10g of pyrrole, 80g of branched epoxy resin, 25g of acetone, and 1g of 2-hydroxy-2-methyl-1-phenyl-1-propanone, mix well to obtain coating A.

[0050] Example 2: A stainless steel workpiece based on nano-injection molding, the preparation method of which includes the following steps:

[0051] Step 1:

[0052] S1: Take stainless steel, wash and dry it with water, immerse it in an alkaline treatment solution for 3 minutes, wash and dry it with water; take it out, then immerse it in an acid treatment solution for 10 minutes, wash and dry it with water; take it out, immerse it in an activation solution for 10 minutes, wash and dry it with water; take it out, then immerse it in a film-forming agent for 10 minutes, wash and dry it with water to obtain the treated stainless steel substrate.

[0053] S2: A 100µm thick coating A is uniformly applied to the surface of the treated stainless steel substrate and cured with ultraviolet light to obtain a surface-treated stainless steel substrate.

[0054] S3: Take a surface-treated stainless steel substrate, react it at 120℃ for 5 minutes, use polyamide mixture for nano-injection molding at a pressure of 110MPa, anneal it, and obtain a stainless steel workpiece based on nano-injection molding.

[0055] The polyamide mixture includes thiolized polyamide and polyamide; the mass ratio of thiolized polyamide to polyamide is 1:1.

[0056] The alkaline treatment solution uses deionized water as a solvent and consists of the following components: 15 g / L sodium hydroxide, 12 g / L sodium carbonate, and 2 g / L OP-10 emulsifier.

[0057] The acid treatment solution uses deionized water as a solvent and consists of the following components: phosphoric acid, with a concentration of 20%;

[0058] The activation solution uses deionized water as a solvent and consists of the following components: 17 g / L sodium peroxide, 9 g / L ammonium hydrogen fluoride, 7 g / L glycerol, 2 g / L acetic acid, and 2 g / L boric acid.

[0059] The film-forming agent uses deionized water as a solvent and consists of the following components: 17 g / L citric acid, 12 g / L sodium thiosulfate, and 10 g / L sodium dihydrogen borate.

[0060] Step 2: Preparation of chitosan-modified silica:

[0061] S1: Preparation of wrinkled silica:

[0062] Take 6g of cetyltrimethylammonium bromide, 3.5g of urea, and 200mL of deionized water, stir well, add 8mL of butanol and 150mL of cyclohexane, and stir for 30min; add 22mL of tetraethyl orthosilicate, stir for 30min, then heat to 70℃, stir for 22h, centrifuge, dry, and then calcine at 550℃ to obtain wrinkled silica;

[0063] S2: Preparation of vinyl chitosan:

[0064] Take 10g chitosan, 50g formaldehyde, and 22g acetic acid, mix them evenly, add 20g acrolein after 1 hour, heat to 50℃, stir for 8 hours, filter, wash, and dry to obtain vinyl chitosan.

[0065] S3: Preparation of chitosan-modified silica:

[0066] Take a 2% (w / w) aqueous solution of glacial acetic acid and vinyl chitosan, stir evenly to obtain a 0.5% (w / w) chitosan acetic acid solution; take 5 mL of 3-glycidyl ether trimethoxysilane and 100 mL of chitosan acetic acid solution and stir for 12 h, add 1 g of wrinkled silica, stir for 10 h, centrifuge, wash and dry to obtain chitosan modified silica;

[0067] Step 3: Preparation of thiolized polyamide:

[0068] S1: Take 2g of pyromellitic methyl chloride, 0.2g of lithium chloride, and 20mL of N,N-dimethylacetamide, stir for 30min, add 0.4mL of pyridine and 0.2g of ethylenediamine under ice bath conditions, stir for 2h, raise the temperature to 35℃, and react for 12h to obtain hyperbranched polyamide;

[0069] S2: Take 25g of hyperbranched polyamide and 13g of epichlorohydrin, mix them evenly, react at 50℃ for 2h, then ripen at 30℃, add 12g of thiourea, heat to 80℃ and react for 22h, purify and dry to obtain thiolized polyamide.

[0070] Step 4: Preparation of Coating A:

[0071] Take 5g of chitosan-modified silica and 10mL of butanone, stir well, add 37g of epoxy curing agent, mix well, add 10g of pyrrole, 80g of branched epoxy resin, 25g of acetone, and 1g of 2-hydroxy-2-methyl-1-phenyl-1-propanone, mix well to obtain coating A.

[0072] Example 3: A stainless steel workpiece based on nano-injection molding, the preparation method of which includes the following steps:

[0073] Step 1:

[0074] S1: Take stainless steel, wash and dry it with water, immerse it in an alkaline treatment solution for 5 minutes, wash and dry it with water; take it out, then immerse it in an acid treatment solution for 12 minutes, wash and dry it with water; take it out, immerse it in an activation solution for 12 minutes, wash and dry it with water; take it out, then immerse it in a film-forming agent for 12 minutes, wash and dry it with water to obtain the treated stainless steel substrate.

[0075] S2: A 100µm thick coating A is uniformly applied to the surface of the treated stainless steel substrate and cured with ultraviolet light to obtain a surface-treated stainless steel substrate.

[0076] S3: Take a surface-treated stainless steel substrate, react it at 150℃ for 10 min, use polyamide mixture for nano-injection molding at a pressure of 130 MPa, anneal it, and obtain a stainless steel workpiece based on nano-injection molding.

[0077] The polyamide mixture includes thiolized polyamide and polyamide; the mass ratio of thiolized polyamide to polyamide is 1:1.2.

[0078] The alkaline treatment solution uses deionized water as a solvent and consists of the following components: 25 g / L sodium hydroxide, 17 g / L sodium carbonate, and 2.5 g / L OP-10 emulsifier.

[0079] The acid treatment solution uses deionized water as a solvent and consists of the following components: phosphoric acid, with a concentration of 40%;

[0080] The activation solution uses deionized water as a solvent and consists of the following components: 22 g / L sodium peroxide, 13 g / L ammonium bifluoride, 10 g / L glycerol, 4 g / L acetic acid, and 3 g / L boric acid.

[0081] The film-forming agent uses deionized water as a solvent and consists of the following components: 20 g / L citric acid, 17 g / L sodium thiosulfate, and 15 g / L sodium dihydrogen borate.

[0082] Step 2: Preparation of chitosan-modified silica:

[0083] S1: Preparation of wrinkled silica:

[0084] Take 6g of cetyltrimethylammonium bromide, 3.5g of urea, and 200mL of deionized water, stir well, add 8mL of butanol and 150mL of cyclohexane, and stir for 40min; add 22mL of tetraethyl orthosilicate, stir for 40min, then heat to 75℃, stir for 26h, centrifuge, dry, and then calcine at 555℃ to obtain wrinkled silica;

[0085] S2: Preparation of vinyl chitosan:

[0086] Take 10g chitosan, 50g formaldehyde, and 22g acetic acid, mix them evenly, and after 2 hours, add 20g acrolein, heat to 55℃, stir for 12 hours, filter, wash, and dry to obtain vinyl chitosan.

[0087] S3: Preparation of chitosan-modified silica:

[0088] Take a 2% (w / w) aqueous solution of glacial acetic acid and vinyl chitosan, stir evenly to obtain a 0.5% (w / w) chitosan acetic acid solution; take 5 mL of 3-glycidyl ether trimethoxysilane and 100 mL of chitosan acetic acid solution and stir for 14 h, add 1 g of wrinkled silica, stir for 12 h, centrifuge, wash and dry to obtain chitosan modified silica;

[0089] Step 3: Preparation of thiolized polyamide:

[0090] S1: Take 2g of pyromellitic methyl chloride, 0.2g of lithium chloride, and 20mL of N,N-dimethylacetamide, stir for 40min, add 0.4mL of pyridine and 0.2g of ethylenediamine under ice bath conditions, stir for 3h, raise the temperature to 40℃, and react for 16h to obtain hyperbranched polyamide;

[0091] S2: Take 25g of hyperbranched polyamide and 13g of epichlorohydrin, mix them evenly, react at 55℃ for 3h, then ripen at 30℃, add 12g of thiourea, heat to 82℃ and react for 26h, purify and dry to obtain thiolized polyamide.

[0092] Step 4: Preparation of Coating A:

[0093] Take 5g of chitosan-modified silica and 10mL of butanone, stir well, add 37g of epoxy curing agent, mix well, add 10g of pyrrole, 80g of branched epoxy resin, 25g of acetone, and 1g of 2-hydroxy-2-methyl-1-phenyl-1-propanone, mix well to obtain coating A.

[0094] Comparative Example 1: Silicon dioxide was used instead of wrinkled silicon dioxide, otherwise the same as in Example 1:

[0095] Step 1:

[0096] S1: Take stainless steel, wash and dry it with water, immerse it in an alkaline treatment solution for 4 minutes, wash and dry it with water; take it out, then immerse it in an acid treatment solution for 11 minutes, wash and dry it with water; take it out, immerse it in an activation solution for 11 minutes, wash and dry it with water; take it out, then immerse it in a film-forming agent for 11 minutes, wash and dry it with water to obtain the treated stainless steel substrate.

[0097] S2: A 100µm thick coating A is uniformly applied to the surface of the treated stainless steel substrate and cured with ultraviolet light to obtain a surface-treated stainless steel substrate.

[0098] S3: Take a surface-treated stainless steel substrate, react it at 140℃ for 8 minutes, use polyamide mixture for nano-injection molding at a pressure of 120MPa, anneal it, and obtain a stainless steel workpiece based on nano-injection molding.

[0099] The polyamide mixture includes thiolized polyamide and polyamide; the mass ratio of thiolized polyamide to polyamide is 1:1.1.

[0100] The alkaline treatment solution uses deionized water as a solvent and consists of the following components: 20 g / L sodium hydroxide, 15 g / L sodium carbonate, and 2.3 g / L OP-10 emulsifier.

[0101] The acid treatment solution uses deionized water as a solvent and consists of the following components: phosphoric acid, with a concentration of 30%;

[0102] The activation solution uses deionized water as a solvent and consists of the following components: 20 g / L sodium peroxide, 11 g / L ammonium hydrogen fluoride, 8 g / L glycerol, 3 g / L acetic acid, and 2.5 g / L boric acid.

[0103] The film-forming agent uses deionized water as a solvent and consists of the following components: 18 g / L citric acid, 15 g / L sodium thiosulfate, and 12 g / L sodium dihydrogen borate.

[0104] Step 2: Preparation of chitosan-modified silica:

[0105] S1: Preparation of vinyl chitosan:

[0106] Take 10g chitosan, 50g formaldehyde, and 22g acetic acid, mix them evenly, add 20g acrolein after 1.5h, heat to 53℃, stir for 10h, filter, wash, and dry to obtain vinyl chitosan.

[0107] S2: Preparation of chitosan-modified silica:

[0108] Take a 2% (w / w) aqueous solution of glacial acetic acid and vinyl chitosan, stir evenly to obtain a 0.5% (w / w) chitosan acetic acid solution; take 5 mL of 3-glycidyl ether trimethoxysilane and 100 mL of chitosan acetic acid solution and stir for 13 h, add 1 g of silica, stir for 11 h, centrifuge, wash and dry to obtain chitosan modified silica;

[0109] Step 3: Preparation of thiolized polyamide:

[0110] S1: Take 2g of pyromellitic methyl chloride, 0.2g of lithium chloride, and 20mL of N,N-dimethylacetamide, stir for 35min, add 0.4mL of pyridine and 0.2g of ethylenediamine under ice bath conditions, stir for 2.5h, raise the temperature to 38℃, and react for 14h to obtain hyperbranched polyamide;

[0111] S2: Take 25g of hyperbranched polyamide and 13g of epichlorohydrin, mix them evenly, react at 53℃ for 2.5h, then ripen at 30℃, add 12g of thiourea, heat to 81℃ and react for 24h, purify and dry to obtain thiolized polyamide.

[0112] Step 4: Preparation of Coating A:

[0113] Take 5g of chitosan-modified silica and 10mL of butanone, stir well, add 37g of epoxy curing agent, mix well, add 10g of pyrrole, 80g of branched epoxy resin, 25g of acetone, and 1g of 2-hydroxy-2-methyl-1-phenyl-1-propanone, mix well to obtain coating A.

[0114] Comparative Example 2: Without vinyl chitosan loading, otherwise the same as Example 1:

[0115] Step 1:

[0116] S1: Take stainless steel, wash and dry it with water, immerse it in an alkaline treatment solution for 4 minutes, wash and dry it with water; take it out, then immerse it in an acid treatment solution for 11 minutes, wash and dry it with water; take it out, immerse it in an activation solution for 11 minutes, wash and dry it with water; take it out, then immerse it in a film-forming agent for 11 minutes, wash and dry it with water to obtain the treated stainless steel substrate.

[0117] S2: A 100µm thick coating A is uniformly applied to the surface of the treated stainless steel substrate and cured with ultraviolet light to obtain a surface-treated stainless steel substrate.

[0118] S3: Take a surface-treated stainless steel substrate, react it at 140℃ for 8 minutes, use polyamide mixture for nano-injection molding at a pressure of 120MPa, anneal it, and obtain a stainless steel workpiece based on nano-injection molding.

[0119] The polyamide mixture includes thiolized polyamide and polyamide; the mass ratio of thiolized polyamide to polyamide is 1:1.1.

[0120] The alkaline treatment solution uses deionized water as a solvent and consists of the following components: 20 g / L sodium hydroxide, 15 g / L sodium carbonate, and 2.3 g / L OP-10 emulsifier.

[0121] The acid treatment solution uses deionized water as a solvent and consists of the following components: phosphoric acid, with a concentration of 30%;

[0122] The activation solution uses deionized water as a solvent and consists of the following components: 20 g / L sodium peroxide, 11 g / L ammonium hydrogen fluoride, 8 g / L glycerol, 3 g / L acetic acid, and 2.5 g / L boric acid.

[0123] The film-forming agent uses deionized water as a solvent and consists of the following components: 18 g / L citric acid, 15 g / L sodium thiosulfate, and 12 g / L sodium dihydrogen borate.

[0124] Step 2: Preparation of wrinkled silica:

[0125] Take 6g of cetyltrimethylammonium bromide, 3.5g of urea, and 200mL of deionized water, stir well, add 8mL of butanol and 150mL of cyclohexane, and stir for 35min; add 22mL of tetraethyl orthosilicate, stir for 35min, then heat to 72℃, stir for 24h, centrifuge, dry, and then calcine at 552℃ to obtain wrinkled silica;

[0126] Step 3: Preparation of thiolized polyamide:

[0127] S1: Take 2g of pyromellitic methyl chloride, 0.2g of lithium chloride, and 20mL of N,N-dimethylacetamide, stir for 35min, add 0.4mL of pyridine and 0.2g of ethylenediamine under ice bath conditions, stir for 2.5h, raise the temperature to 38℃, and react for 14h to obtain hyperbranched polyamide;

[0128] S2: Take 25g of hyperbranched polyamide and 13g of epichlorohydrin, mix them evenly, react at 53℃ for 2.5h, then ripen at 30℃, add 12g of thiourea, heat to 81℃ and react for 24h, purify and dry to obtain thiolized polyamide.

[0129] Step 4: Preparation of Coating A:

[0130] Take 5g of wrinkled silica and 10mL of butanone, stir well, add 37g of epoxy curing agent, mix well, add 10g of pyrrole, 80g of branched epoxy resin, 25g of acetone, and 1g of 2-hydroxy-2-methyl-1-phenyl-1-propanone, mix well to obtain coating A.

[0131] Comparative Example 3: No thiolized polyamide was added; all other aspects were the same as in Example 1.

[0132] Step 1:

[0133] S1: Take stainless steel, wash and dry it with water, immerse it in an alkaline treatment solution for 4 minutes, wash and dry it with water; take it out, then immerse it in an acid treatment solution for 11 minutes, wash and dry it with water; take it out, immerse it in an activation solution for 11 minutes, wash and dry it with water; take it out, then immerse it in a film-forming agent for 11 minutes, wash and dry it with water to obtain the treated stainless steel substrate.

[0134] S2: A 100µm thick coating A is uniformly applied to the surface of the treated stainless steel substrate and cured with ultraviolet light to obtain a surface-treated stainless steel substrate.

[0135] S3: Take a surface-treated stainless steel substrate, react it at 140℃ for 8 minutes, use polyamide for nano-injection molding at a pressure of 120MPa, and anneal to obtain a stainless steel workpiece based on nano-injection molding.

[0136] The alkaline treatment solution uses deionized water as a solvent and consists of the following components: 20 g / L sodium hydroxide, 15 g / L sodium carbonate, and 2.3 g / L OP-10 emulsifier.

[0137] The acid treatment solution uses deionized water as a solvent and consists of the following components: phosphoric acid, with a concentration of 30%;

[0138] The activation solution uses deionized water as a solvent and consists of the following components: 20 g / L sodium peroxide, 11 g / L ammonium hydrogen fluoride, 8 g / L glycerol, 3 g / L acetic acid, and 2.5 g / L boric acid.

[0139] The film-forming agent uses deionized water as a solvent and consists of the following components: 18 g / L citric acid, 15 g / L sodium thiosulfate, and 12 g / L sodium dihydrogen borate.

[0140] Step 2: Preparation of chitosan-modified silica:

[0141] S1: Preparation of wrinkled silica:

[0142] Take 6g of cetyltrimethylammonium bromide, 3.5g of urea, and 200mL of deionized water, stir well, add 8mL of butanol and 150mL of cyclohexane, and stir for 35min; add 22mL of tetraethyl orthosilicate, stir for 35min, then heat to 72℃, stir for 24h, centrifuge, dry, and then calcine at 552℃ to obtain wrinkled silica;

[0143] S2: Preparation of vinyl chitosan:

[0144] Take 10g chitosan, 50g formaldehyde, and 22g acetic acid, mix them evenly, add 20g acrolein after 1.5h, heat to 53℃, stir for 10h, filter, wash, and dry to obtain vinyl chitosan.

[0145] S3: Preparation of chitosan-modified silica:

[0146] Take a 2% (w / w) aqueous solution of glacial acetic acid and vinyl chitosan, stir evenly to obtain a 0.5% (w / w) chitosan acetic acid solution; take 5 mL of 3-glycidyl ether trimethoxysilane and 100 mL of chitosan acetic acid solution and stir for 13 h, add 1 g of wrinkled silica, stir for 11 h, centrifuge, wash and dry to obtain chitosan modified silica;

[0147] Step 3: Preparation of Coating A:

[0148] Take 5g of chitosan-modified silica and 10mL of butanone, stir well, add 37g of epoxy curing agent, mix well, add 10g of pyrrole, 80g of branched epoxy resin, 25g of acetone, and 1g of 2-hydroxy-2-methyl-1-phenyl-1-propanone, mix well to obtain coating A.

[0149] experiment:

[0150] Stainless steel workpieces based on nano-injection molding prepared in Examples 1-3 and Comparative Examples 1-3 were used. The sample size of the nano-injection molded stainless steel workpieces was 50mm × 12.5mm × 2mm, and the thickness of the nano-injection molding layer was 20µm. The peel strength and tensile strength between the stainless steel substrate and the nano-injection molding layer were tested, and the data are shown in Table 1 below.

[0151] Table 1

[0152]

[0153] Conclusion: The data comparison in the table shows that in Comparative Example 1, using silica instead of wrinkled silica resulted in less loaded vinyl chitosan and a decrease in peel strength. In Comparative Example 2, without loaded vinyl chitosan, the peel strength and tensile strength between the stainless steel substrate and the nano-injection molding layer decreased significantly. In Comparative Example 3, without the addition of thiolized polyamide, the peel strength and tensile strength between the stainless steel substrate and the nano-injection molding layer decreased. Examples 1-3 of this invention coat the stainless steel surface with a resin containing chitosan-modified silica, enhancing the bonding strength between stainless steel and plastic. This invention uses a polyamide mixture for injection molding, which includes thiolized polyamide and polyamide. Thiol groups have strong hydrophobicity; thiolized polyamide can reduce moisture penetration and improve the stability of the material in humid and hot environments. The thiol groups in the polyamide mixture of this invention can also react with the vinyl groups on the silica, further enhancing the bonding strength between stainless steel and plastic.

[0154] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for surface treatment of a stainless steel workpiece based on nanoinjection, characterized in that: It comprises the following steps: Step one: take stainless steel, wash with water, dry, immerse in alkali treatment liquid for 3-5 min, wash with water, dry; take out, then immerse in acid treatment liquid for 10-12 min, wash with water, dry; take out, immerse in activation liquid for 10-12 min, wash with water, dry; take out, then immerse in film forming agent for 10-12 min, wash with water, dry, to obtain the treated stainless steel substrate; Step two: evenly coat the coating A on the surface of the treated stainless steel substrate, and use ultraviolet light to cure, to obtain the surface treated stainless steel substrate; The preparation method of the crumpled silicon dioxide is: take cetyltrimethylammonium bromide, urea, deionized water, stir uniformly, add butanol, cyclohexane, stir for 30-40 min; add tetraethyl orthosilicate dropwise, stir for 30-40 min, then heat to 70-75℃, stir for 22-26 h, centrifuge, dry, then calcine at 550-555℃, to obtain the crumpled silicon dioxide; The preparation method of the coating A is: take chitosan modified silicon dioxide, butanone, stir uniformly, add 37g epoxy curing agent, mix uniformly, add pyrrole, branched epoxy resin, 2-hydroxy-2-methyl-1-phenyl-1-propanone, acetone, mix uniformly, to obtain the coating A; The preparation method of the chitosan modified silicon dioxide is: It comprises the following steps: S1: take chitosan, formaldehyde, acetic acid, mix uniformly, 1-2h, add propylene aldehyde, heat to 50-55℃, stir for 8-12h, filter, wash, dry, to obtain the vinyl chitosan; S2: take glacial acetic acid aqueous solution, vinyl chitosan, stir uniformly, to obtain the chitosan acetic acid solution; take 3-glycidyl ether trimethoxysilane, chitosan acetic acid solution, stir for 12-14h, add crumpled silicon dioxide, stir for 10-12h, centrifuge, wash, dry, to obtain the chitosan modified silicon dioxide.

2. The method for surface treatment of a stainless steel workpiece based on nano-injection molding according to claim 1, characterized in that: The alkali treatment liquid takes ionized water as the solvent, and is composed of the following components: 15-25g / L of sodium hydroxide, 12-17g / L of sodium carbonate, and 2-2.5g / L of OP-10 emulsifier; The acid treatment liquid takes ionized water as the solvent, and is composed of the following components: phosphoric acid, with a concentration of 20%-40%; The activation liquid takes ionized water as the solvent, and is composed of the following components: 17-22g / L of sodium peroxide, 9-13g / L of ammonium hydrogen fluoride, 7-10g / L of glycerol, 2-4g / L of acetic acid, and 2-3g / L of boric acid; The film forming agent takes ionized water as the solvent, and is composed of the following components: 17-20g / L of citric acid, 12-17g / L of sodium thiosulfate, and 10-15g / L of boric acid dihydrogen sodium.

3. A method for manufacturing a stainless steel workpiece based on nano-injection, characterized in that: It comprises the following steps: Take the surface treated stainless steel substrate in any one of claims 1-2, react at 120-150℃ for 5-10 min, use polyamide mixture for nano injection molding, the pressure is 110-130MPa, anneal, to obtain a nano injection molding based stainless steel workpiece.

4. The method for preparing a stainless steel workpiece based on nano-injection molding according to claim 3, characterized in that: The polyamide mixture comprises mercapto-polyamide and polyamide, and the mass ratio of mercapto-polyamide to polyamide is 1: (1-1.2).

5. The method for manufacturing a stainless steel workpiece based on nano-injection molding according to claim 4, characterized in that: The preparation method of the mercapto-polyamide comprises the following steps: taking hyperbranched polyamide and epichlorohydrin, mixing uniformly, reacting at 50-55 ℃ for 2-3 h, then aging at 30 ℃, adding thiourea, and reacting at 80-82 ℃ for 22-26 h, and then purifying and drying to obtain the mercapto-polyamide.

6. The method for preparing a stainless steel workpiece based on nano-injection molding according to claim 5, characterized in that: The preparation method of the hyperbranched polyamide comprises the following steps: taking trimesoyl chloride, lithium chloride and N, N-dimethylacetamide, stirring for 30-40 min, adding pyridine and ethylenediamine under ice bath condition, stirring for 2-3 h, and then reacting at 35-40 ℃ for 12-16 h to obtain the hyperbranched polyamide.

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