CN116180062A - Surface treating agent used before galvanized sheet coating - Google Patents
Surface treating agent used before galvanized sheet coating Download PDFInfo
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- CN116180062A CN116180062A CN202211724811.7A CN202211724811A CN116180062A CN 116180062 A CN116180062 A CN 116180062A CN 202211724811 A CN202211724811 A CN 202211724811A CN 116180062 A CN116180062 A CN 116180062A
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- galvanized sheet
- treating agent
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- 239000003795 chemical substances by application Substances 0.000 title claims abstract description 38
- 239000011248 coating agent Substances 0.000 title claims abstract description 15
- 238000000576 coating method Methods 0.000 title claims abstract description 15
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims abstract description 25
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 18
- 239000012756 surface treatment agent Substances 0.000 claims abstract description 13
- 239000006087 Silane Coupling Agent Substances 0.000 claims abstract description 11
- FZHAPNGMFPVSLP-UHFFFAOYSA-N silanamine Chemical compound [SiH3]N FZHAPNGMFPVSLP-UHFFFAOYSA-N 0.000 claims abstract description 8
- 150000007522 mineralic acids Chemical class 0.000 claims abstract description 7
- CTENFNNZBMHDDG-UHFFFAOYSA-N Dopamine hydrochloride Chemical compound Cl.NCCC1=CC=C(O)C(O)=C1 CTENFNNZBMHDDG-UHFFFAOYSA-N 0.000 claims abstract description 5
- 229960001149 dopamine hydrochloride Drugs 0.000 claims abstract description 5
- 238000002156 mixing Methods 0.000 claims abstract description 3
- 238000000034 method Methods 0.000 claims description 17
- 230000008569 process Effects 0.000 claims description 15
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 7
- 229910017604 nitric acid Inorganic materials 0.000 claims description 7
- 238000010422 painting Methods 0.000 claims description 6
- 238000006116 polymerization reaction Methods 0.000 claims description 5
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 claims description 3
- 229910000013 Ammonium bicarbonate Inorganic materials 0.000 claims description 3
- 235000012538 ammonium bicarbonate Nutrition 0.000 claims description 3
- 239000001099 ammonium carbonate Substances 0.000 claims description 3
- 239000012224 working solution Substances 0.000 claims description 3
- HZAXFHJVJLSVMW-UHFFFAOYSA-N 2-Aminoethan-1-ol Chemical compound NCCO HZAXFHJVJLSVMW-UHFFFAOYSA-N 0.000 claims description 2
- 239000003973 paint Substances 0.000 abstract description 23
- VYFYYTLLBUKUHU-UHFFFAOYSA-N dopamine Chemical compound NCCC1=CC=C(O)C(O)=C1 VYFYYTLLBUKUHU-UHFFFAOYSA-N 0.000 abstract description 16
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 abstract description 15
- 229910000077 silane Inorganic materials 0.000 abstract description 15
- 238000005260 corrosion Methods 0.000 abstract description 14
- 230000007797 corrosion Effects 0.000 abstract description 14
- 229960003638 dopamine Drugs 0.000 abstract description 8
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 abstract description 3
- 229910052726 zirconium Inorganic materials 0.000 abstract description 3
- 239000010410 layer Substances 0.000 description 19
- 229920001690 polydopamine Polymers 0.000 description 11
- 238000005406 washing Methods 0.000 description 10
- 239000000463 material Substances 0.000 description 9
- 238000011282 treatment Methods 0.000 description 9
- 238000004381 surface treatment Methods 0.000 description 8
- 238000005238 degreasing Methods 0.000 description 6
- 229910052710 silicon Inorganic materials 0.000 description 6
- 239000010703 silicon Substances 0.000 description 6
- 150000003754 zirconium Chemical class 0.000 description 6
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 5
- 230000000052 comparative effect Effects 0.000 description 5
- 125000000524 functional group Chemical group 0.000 description 5
- 239000000178 monomer Substances 0.000 description 5
- 239000000758 substrate Substances 0.000 description 5
- 229910052725 zinc Inorganic materials 0.000 description 5
- 239000011701 zinc Substances 0.000 description 5
- 239000008367 deionised water Substances 0.000 description 4
- 229910021641 deionized water Inorganic materials 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 230000002378 acidificating effect Effects 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000004132 cross linking Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000001962 electrophoresis Methods 0.000 description 3
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 229920000642 polymer Polymers 0.000 description 3
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 229910008051 Si-OH Inorganic materials 0.000 description 2
- 229910002808 Si–O–Si Inorganic materials 0.000 description 2
- 229910006358 Si—OH Inorganic materials 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 229910007542 Zn OH Inorganic materials 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 2
- 230000001070 adhesive effect Effects 0.000 description 2
- YCIMNLLNPGFGHC-UHFFFAOYSA-N catechol Chemical compound OC1=CC=CC=C1O YCIMNLLNPGFGHC-UHFFFAOYSA-N 0.000 description 2
- 238000004210 cathodic protection Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 229910052739 hydrogen Inorganic materials 0.000 description 2
- 239000001257 hydrogen Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000006068 polycondensation reaction Methods 0.000 description 2
- 239000011347 resin Substances 0.000 description 2
- 229920005989 resin Polymers 0.000 description 2
- 239000002893 slag Substances 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 239000008399 tap water Substances 0.000 description 2
- 235000020679 tap water Nutrition 0.000 description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- -1 alcohol amine Chemical class 0.000 description 1
- 150000003863 ammonium salts Chemical class 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 239000010953 base metal Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000010960 cold rolled steel Substances 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000005536 corrosion prevention Methods 0.000 description 1
- 238000005237 degreasing agent Methods 0.000 description 1
- 239000013527 degreasing agent Substances 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N phenol group Chemical group C1(=CC=CC=C1)O ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000011241 protective layer Substances 0.000 description 1
- 238000005057 refrigeration Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 239000011550 stock solution Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
- 238000009423 ventilation Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
- C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
- C23C22/48—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 not containing phosphates, hexavalent chromium compounds, fluorides or complex fluorides, molybdates, tungstates, vanadates or oxalates
- C23C22/50—Treatment of iron or alloys based thereon
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D13/00—Electrophoretic coating characterised by the process
- C25D13/20—Pretreatment
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2222/00—Aspects relating to chemical surface treatment of metallic material by reaction of the surface with a reactive medium
- C23C2222/20—Use of solutions containing silanes
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Mechanical Engineering (AREA)
- Electrochemistry (AREA)
- Chemical Treatment Of Metals (AREA)
Abstract
The invention discloses a surface treating agent used before coating a galvanized plate, which is prepared by mixing the following components in parts by mass: 40-80 g of dopamine hydrochloride, 5-10 g of hydrogen peroxide, 20-50 g of oligomer of amino silane coupling agent, 10-20 g of inorganic acid and the balance of water. Compared with the traditional zirconium-based phosphorus-free pretreatment agent, the surface treatment agent disclosed by the invention utilizes the characteristics of dopamine and silane oligomers, and the formed film has good compactness, good corrosion resistance and high binding force with a paint film.
Description
Technical Field
The invention relates to a surface treating agent used before coating of galvanized plates.
Background
With the development of social economy, the requirements of people on the performance and the attractive appearance of materials are higher and higher, and a large number of galvanized thin sheets are used in the fields of automobile manufacture, refrigeration cases, building industry, ventilation and heating facilities, furniture manufacture and the like. Zinc plating is an important steel corrosion prevention method, not only because zinc can form a compact protective layer on the surface of steel, but also because zinc has a cathodic protection effect, and when the galvanized layer is damaged, the zinc can still prevent the iron base metal from being corroded through the cathodic protection effect.
The galvanized material has the advantages that the corrosion resistance is greatly improved compared with that of the traditional cold-rolled steel sheet due to the existence of a galvanized layer, but if a paint film is directly coated without any surface pretreatment, the binding force between the galvanized layer and the paint is poor, and the problems of peeling and the like can occur in the actual use process, so that the corrosion resistance is invalid. Therefore, the galvanized sheet needs to be subjected to surface treatment before being coated to further improve the corrosion resistance of the galvanized material and enhance the adhesion property between the galvanized material and the coating.
At present, the surface treatment technology of galvanized sheets before coating mostly adopts a phosphating treatment process. The phosphating treatment method is not environment-friendly on one hand because of heavy metal ions such as zinc, manganese, nickel and the like and a large amount of phosphorus; on the other hand, in terms of use cost, a large amount of phosphorized slag can be generated in the phosphorization treatment process, a set of slag removing device is needed to be matched with the phosphorization treatment process, and the use temperature of the phosphorization process is 40-60 ℃, so that auxiliary heating equipment and a heat source are needed to heat the phosphorization tank. Meanwhile, a large amount of countercurrent water is needed to rinse the workpiece after phosphating. The phosphating process is therefore subject to great environmental and cost pressures.
The phosphorus-free pretreatment product mainly based on zirconium solves the environmental protection problem of the traditional phosphating pretreatment product, but the development original purpose is to apply the pretreatment technology of the cold-rolled sheet, the application on the galvanized sheet is not mature enough, and the adhesive force and the cycle corrosion performance can not stably meet the industry requirement. This is because the galvanized sheet has internal stress due to the presence of the galvanized layer, and the paint film adhesion must overcome the internal stress, so that the galvanized sheet has higher requirements on the adhesion between the film layer and the paint film.
Disclosure of Invention
The invention aims to: the invention aims to provide a surface treating agent used before coating of a galvanized sheet, which can form a continuous and compact film layer on the surface of the galvanized sheet, wherein the film layer has a net structure and contains a large number of active functional groups capable of acting with a paint film, so that the film layer has good corrosion resistance and good physical bonding capability with subsequent paint.
The technical scheme is as follows: the surface treating agent for galvanized sheet before painting is prepared by mixing the following components in mass: 40-80 g of dopamine hydrochloride, 5-10 g of hydrogen peroxide, 20-50 g of oligomer of amino silane coupling agent, 10-20 g of inorganic acid and the balance of water.
Wherein the pH value of the surface treating agent stock solution is 2-5.
Wherein the polymerization degree of the oligomer of the amino silane coupling agent is 3-10. Too low a polymerization degree to form a crosslinked structure, too high a polymerization degree may deteriorate solubility and stability; preferably AMEO from the winning company, model Dynasylan1151.
Wherein the inorganic acid is nitric acid, and the mass percentage concentration of the nitric acid is 40%.
Wherein the mass percentage concentration of the hydrogen peroxide is 27.5%.
The use concentration of the surface treating agent is 3-6%, namely the surface treating agent with the formula is diluted into a diluted solution with the mass percent concentration of 3-6% by using deionized water, and the working solution is obtained. During the use process, ammonium bicarbonate or monoethanolamine is used to regulate the pH value of the working solution to 8-9.
The action mechanism of each component of the surface treating agent is as follows:
(1) Dopamine hydrochloride
In aqueous solution, dopamine can rapidly form a polydopamine film with super-strong viscosity on the surfaces of various materials (such as metal, oxide, polymer, semiconductor and ceramic) through an oxidation-polymerization process. The surface of the film contains abundant catechol and amino active groups, and a series of crosslinking reactions can occur, so that the film is adsorbed on the surface of the galvanized plate by utilizing the strong adsorptivity of polydopamine to form a compact film, and the corrosion resistance of the film is improved; meanwhile, the bonding force between the base material and the paint film can be effectively improved by utilizing the crosslinking reaction between a large number of active groups on the surface of polydopamine and the paint film component.
(2) Hydrogen peroxide solution H 2 O 2 And an inorganic acid
Dopamine is relatively stable and is not easy to polymerize under the acidic condition. Hydrogen peroxide is relatively stable and not easy to decompose under acidic conditions. The surface treating agent adopts inorganic acid to reduce the pH value of the product, and ensures the storage stability of the product. In the using process, ammonium salt or alcohol amine substances are used for adjusting the pH value to 8-9, so that the hydrogen peroxide is promoted to decompose oxygen to induce dopamine to polymerize to form polydopamine, and the polydopamine is firmly adsorbed on the surface of the substrate.
(3) Oligomer of amino silane coupling agent
The silane coupling agent oligomer can hydrolyze in aqueous solution to form silicon hydroxyl Si-OH, the silicon hydroxyl can further perform polycondensation reaction with Zn-OH groups to form firm covalent bonds (Zn-O-Si), meanwhile, silane polymers are mutually dehydrated and polycondensed through the rest of the-OH groups to form a three-dimensional network structure of Si-O-Si on the surface of the galvanized plate, meanwhile, the silicon hydroxyl can be dehydrated and combined with phenolic hydroxyl of polydopamine, and a crosslinked network structure film layer is formed through the combination of various hydroxyl groups at the interface of a metal substrate, so that the compactness and corrosion resistance of the film layer are greatly improved, and the bonding force between the metal substrate and a paint film is improved. On the other hand, the functional group R on the other side of the silane carries a special functional group (amino) which can react with resin in a paint film in the curing process, and the R group is a standard for selecting silane oligomer, so that amino silane oligomer is used, and the binding force between the galvanized sheet and the paint film is further improved.
The aminosilane contains hydrogen bonds, can form hydrogen bonds between molecules and with a metal substrate, and is favorable for bonding between silane and between silane and dopamine to form a compact reticular structure membrane layer. The oligomers are more prone to form crosslinked network structures relative to the silane monomers, and the silane oligomer hydrolysis products have the following structural formula:
three-dimensional network structure of polydopamine composite silane coupling agent film layer:
the beneficial effects are that: compared with the prior art, the invention has the following remarkable advantages: the surface treating agent can improve the corrosion resistance of the surface film layer of the galvanized sheet, and can effectively improve the adhesive force between a galvanized sheet base material and a subsequent paint film, so that the galvanized sheet has excellent circulating corrosion resistance after being coated; compared with the traditional zirconium-based phosphorus-free pretreatment agent, the surface treatment agent disclosed by the invention utilizes the characteristics of dopamine and silane oligomers, and the formed film has good compactness, good corrosion resistance and high binding force with a paint film.
Detailed Description
All components in the surface treating agent are commercial products: hydrogen peroxide, H 2 O 2 The mass percentage is 27.5%; silane monomer KH550, silane oligomer AMEO (brand Dynasylan 1151) was purchased commercially; nitric acid is commercially available, and the mass percentage content is 40%.
Example 1
Test panel: a commercial 180YD galvanized sheet was used, with a gauge (150 mm. Times.70 mm. Times.0.8 mm).
The process flow comprises the following steps:
degreasing and degreasing, running water washing, pure water washing, surface treatment, running water washing, pure water washing, electrophoretic coating, running water washing, pure water washing and solidification
Brief description of each process flow:
degreasing: the degreasing agent for the galvanized sheet is heated by KR-SC6810& KR-SC64L, which is a product of Nanjing, kerun, and is used for soaking the sheet for 5 minutes at 50 ℃ and is assisted with manual swing rubbing to ensure the degreasing and cleaning of the surface.
Washing after degreasing: the washing was performed for 1 minute in tap water at room temperature and 1 minute in pure water.
The preparation of the surface treating agent comprises the following steps:
each kilogram of surface treating agent is prepared by adding the following components by mass:
dopamine hydrochloride: 50g
Hydrogen peroxide (hydrogen peroxide with a mass concentration of 27.5%): 5g
Silane oligomer AMEO (brand dynastylan 1151, winning purchase): 40g
Nitric acid (mass concentration of nitric acid 40%): 15g
And the balance of deionized water.
The use concentration of the galvanized sheet surface treating agent is 5%, namely 50g of the surface treating agent is added into every kilogram of deionized water to obtain diluted treating liquid, the pH value of the treating liquid is regulated to about 8.50 by using ammonium bicarbonate, and the template after degreasing and water washing is soaked and treated by using the treating liquid for 3 minutes.
Washing treatment after surface treatment:
after the surface treatment, the surface is washed in tap water for 1min, and in pure water for 1min.
And (3) electrophoretic coating:
the galvanized sheet material with the surface wet and treated by the surface treating agent is subjected to electrophoresis by using HT8000C water-based cathode electrophoresis paint produced by Xiangjiang Guangxi paint company, and the thickness of the surface paint film of the obtained test sheet is 20+/-1 mu m. The treated panels were rinsed with deionized water for 30 seconds. And (3) solidifying the washed electrophoresis test plate for 20 minutes at 170 ℃, taking out, and airing at room temperature. The phosphating surface treatment agent and the zirconium salt surface treatment agent are synchronously compared. In Table 1, example 1 is a surface treating agent of the present invention, comparative example 3 is a silane oligomer of example 1 replaced with a silane coupling agent monomer of the same type, comparative example 1 is a phosphating surface treating agent (purchased by certain surface treating company in Yangzhou), comparative example 2 is a zirconium salt surface treating agent (product of Nanjing Koun KR-S210), and paint film properties obtained after passing through different surface treating agents are shown in Table 1.
TABLE 1
As shown in Table 1, the galvanized sheet treated with the surface treating agent of the invention has excellent adhesion with paint film, and passes 30-cycle CCT test (30-cycle unilateral maximum diffusion is less than or equal to 2 mm). The comprehensive performance of the surface treating agent is superior to that of zirconium salt surface treating agent, and the performance of the surface treating agent obtained by the oligomer is superior to that of the surface treating agent prepared by the monomer compared with that of the silane coupling agent monomer.
Example 2 (bare film Property after surface treatment)
Example 2 was not subjected to electrophoretic coating, and after surface treatment, it was dried with cold air. The specific treatment was the same as in example 1. Synchronous comparison of phosphating and zirconium salt surface treatments. Example 1 is the surface treatment agent treatment of the present invention, comparative example 1 is the phosphating surface treatment agent treatment, comparative example 2 is the zirconium salt surface treatment agent treatment, and bare film properties obtained after different surface treatment agents are shown in table 2.
TABLE 2
As is clear from Table 2, the bare film treated by the surface treating agent of the present invention has good corrosion resistance (good film compactness), and the corrosion resistance of the bare film is basically equivalent to that of the phosphating surface treating agent, and is superior to that of the zirconium salt surface treating agent.
The surface treating agent for the galvanized sheet before coating solves the problem that the existing phosphorus-free surface treating agent can not stably ensure the binding force between the galvanized sheet and the coating. The surface treating agent ensures the storage stability of the product by utilizing the principle that hydrogen peroxide and dopamine are relatively stable under an acidic condition; the hydrogen peroxide is decomposed under alkaline conditions to induce the dopamine to polymerize to form polydopamine, so that a compact polydopamine film layer is formed in the use process of the product, and the corrosion resistance of the surface of the galvanized sheet is improved; the network structure of the polydopamine film layer contains a large number of active groups and can generate a crosslinking reaction with the curing process of the coating, so that the binding force of the coating and a substrate is ensured; the silane coupling agent oligomer is hydrolyzed in aqueous solution to form silicon hydroxyl Si-OH, the silicon hydroxyl can further perform polycondensation reaction with Zn-OH groups to form firm covalent bonds (Zn-O-Si), and meanwhile, the silane polymer is dehydrated and polycondensed with each other through the rest of the-OH groups to form a Si-O-Si three-dimensional network structure on the surface of the galvanized plate; meanwhile, the silicon hydroxyl groups can be dehydrated and combined with polydopamine phenolic hydroxyl groups, and various hydroxyl groups at the interface of the base material are combined to form a crosslinked reticular structure film layer, so that the compactness of the film layer is greatly improved, and meanwhile, the effect of a gully rivet between the film layer and a paint film is strong, so that the binding force between the film layer and the paint film is improved. On the other hand, the functional group R on the other side of the silane carries a special functional group (amino) which can react with resin in the paint film in the curing process, so that the binding force between the galvanized plate and the paint film is further improved.
Claims (6)
1. The surface treating agent before coating the galvanized sheet is characterized by being prepared by mixing the following components in parts by mass: 40-80 g of dopamine hydrochloride, 5-10 g of hydrogen peroxide, 20-50 g of oligomer of amino silane coupling agent, 10-20 g of inorganic acid and the balance of water.
2. The surface treatment agent for galvanized sheet before painting according to claim 1, characterized in that: the pH of the surface treating agent is 2-5.
3. The surface treatment agent for galvanized sheet before painting according to claim 1, characterized in that: the polymerization degree of the oligomer of the amino silane coupling agent is 3-10.
4. The surface treatment agent for galvanized sheet before painting according to claim 1, characterized in that: the inorganic acid is nitric acid, and the mass percentage concentration of the nitric acid is 40%.
5. The surface treatment agent for galvanized sheet before painting according to claim 1, characterized in that: the mass percentage concentration of the hydrogen peroxide is 27.5%.
6. The surface treatment agent for galvanized sheet before painting according to claim 1, characterized in that: the use concentration of the surface treating agent is 3-6wt%, and the pH value of the working solution is adjusted to 8-9 by ammonium bicarbonate or monoethanolamine in the use process.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211724811.7A CN116180062A (en) | 2022-12-30 | 2022-12-30 | Surface treating agent used before galvanized sheet coating |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211724811.7A CN116180062A (en) | 2022-12-30 | 2022-12-30 | Surface treating agent used before galvanized sheet coating |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116180062A true CN116180062A (en) | 2023-05-30 |
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