A transparent anticorrosive phenolic epoxy varnish and a preparation method thereof

Abstract

The application discloses a transparent anticorrosive phenolic epoxy varnish and a preparation method thereof. According to the mass fraction, the raw material formula of the disclosed phenolic epoxy varnish is composed of phenolic epoxy emulsion 40-90 parts, calcium phosphate oligomer 10-30 parts, water 10-20 parts, epoxy curing agent 10-30 parts and defoaming agent 1-4 parts. The preparation method disclosed by the application is that the prepared phenolic epoxy emulsion, the calcium phosphate oligomer gel and the water are uniformly mixed, then the epoxy curing agent and the defoaming agent are added and uniformly mixed to obtain the high-performance transparent anticorrosive phenolic epoxy varnish. The phenolic epoxy varnish has superior alkali resistance, salt water resistance and salt mist resistance of the cured coating film.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of phenolic epoxy varnish preparation, and particularly relates to a transparent anticorrosive phenolic epoxy varnish and a preparation method thereof. BACKGROUND

[0002] With the increase of the polymerization degree, the relative molecular mass of the phenolic epoxy resin increases, the softening point rises, the epoxy group also increases, the crosslinking density increases, the heat resistance improves, the phenolic epoxy resin structure contains more than two epoxy groups, more aromatic rings with good thermal stability are introduced, higher epoxy functionality can provide more crosslinking points, the crosslinking density is high after curing, a three-dimensional structure with high crosslinking is easily formed, and the cured product exhibits excellent mechanical strength, electrical insulation performance, water resistance, chemical resistance, higher glass transition temperature and thermal stability. However, due to the high viscosity of the phenolic epoxy resin, a solvent or diluent is usually added to reduce the viscosity of the system, a large amount of organic solvent is generated in production and construction, which causes great harm to the environment and human health. With the increasing requirement for environmental protection, it is an inevitable trend to develop a water-based phenolic epoxy resin with higher performance.

[0003] Chinese patent CN101899196B discloses a water-based phenolic epoxy resin emulsion and a preparation method thereof. The prepared phenolic epoxy varnish is modified by introducing carboxyl into the phenolic epoxy resin, and then the carboxyl is neutralized into a hydrophilic group to make the phenolic epoxy resin have certain hydrophilicity, so as to reduce the emulsification difficulty, and then a stable phenolic epoxy emulsion is obtained by using a proper amount of surfactant, and then the film is cured. However, after the epoxy group of the phenolic epoxy resin is connected to the hydrophilic group, on the one hand, the hydrophilicity of the resin increases, and the water resistance decreases, and on the other hand, the number of epoxy groups decreases, and the crosslinking density of the resin during film formation decreases, and the chemical resistance of the obtained coating film is poor.

[0004] Chinese patent CN109679117A discloses a water-based phenolic epoxy resin emulsion and a preparation method thereof. The prepared phenolic epoxy varnish is modified by introducing amino into the phenolic epoxy resin by using alcohol amine, and then the amino is neutralized into a hydrophilic group to make the phenolic epoxy resin have hydrophilicity, and then the emulsion is formed in water. Similarly, after the epoxy group of the phenolic epoxy resin is connected to the hydrophilic group, the hydrophilicity increases, the water resistance decreases, the number of epoxy groups decreases, the crosslinking density of the resin during film formation decreases, and the coating performance is affected. At the same time, the invention uses modified sepiolite to improve the adhesion and hardness of the coating film, but the modified sepiolite and the organic resin are not compatible after simple mixing, the obtained coating becomes opaque, and the improvement of the salt water resistance is limited. SUMMARY

[0005] The present application aims at the problem of poor alkali resistance, salt water resistance and salt mist resistance of the prior art waterborne phenolic epoxy varnish, and provides a kind of transparent anticorrosive phenolic epoxy varnish and a preparation method thereof.The coating formed by the varnish is uniform and transparent, and the hardness, adhesion, alkali resistance and salt water resistance of the coating are significantly improved compared with the prior art, and the comprehensive performance is excellent.

[0006] In order to achieve the object of the present application, the present application provides the following technical solutions:

[0007] A kind of transparent anticorrosive phenolic epoxy varnish is prepared by uniformly mixing phenolic epoxy emulsion, calcium phosphate oligomer, water, epoxy curing agent and defoaming agent.

[0008] The phenolic epoxy emulsion is prepared by uniformly mixing phenolic epoxy resin, long carbon chain alkyl compound, epoxy emulsifier and organic solvent after melting at 110-130 DEG C, cooling to 80-110 DEG C, and adding water dropwise under stirring for 20-40 min;The long carbon chain alkyl compound is long carbon chain alkyl acid or long carbon chain alkyl amide, and the number of carbon atoms is 16-22.

[0009] The calcium phosphate oligomer is prepared by stirring calcium chloride dihydrate and anhydrous ethanol A at room temperature to form a clear solution, adding triethylamine and stirring, then adding uniformly mixed phosphoric acid and anhydrous ethanol B, stirring at room temperature for 8-14 hours, centrifuging and washing.

[0010] To further achieve the object of the present application, preferably, in the preparation of the phenolic epoxy varnish, the phenolic epoxy emulsion is 40-90 parts, the calcium phosphate oligomer is 10-30 parts, the water is 10-20 parts, the epoxy curing agent is 10-30 parts, and the defoaming agent is 1-4 parts by mass.

[0011] Preferably, in the preparation of the phenolic epoxy emulsion, the phenolic epoxy resin is 30-90 parts, the long carbon chain alkyl compound is 2-30 parts, the organic solvent is 4-10 parts, the epoxy emulsifier is 2-40 parts, and the water is 20-60 parts by mass.

[0012] Preferably, in the preparation of the calcium phosphate oligomer, the calcium chloride dihydrate is 0.3-5 parts, the anhydrous ethanol A is 50-90 parts, the triethylamine is 4-10 parts, the phosphoric acid is 0.1-5 parts, and the anhydrous ethanol B is 3-20 parts by mass.

[0013] Preferably, in the preparation of the phenolic epoxy emulsion, the long carbon chain alkyl compound is one or more of oleic acid, stearic acid, myristic acid, palmitoleic acid, oleic acid amide and oleic acid-based palmitic acid amide;The phenolic epoxy resin is one or more of o-cresol epoxy resin, bisphenol A phenolic epoxy resin and phenol type phenolic epoxy resin.

[0014] Preferably, in the preparation of the phenolic epoxy emulsion, the organic solvent is one or more of ethylene glycol butyl ether, propylene glycol methyl ether, diacetone alcohol, acetylacetone, N-methyl pyrrolidine and diethylene glycol butyl ether.

[0015] The phenolic epoxy resin has an epoxy equivalent weight of 160-250 g / eq.

[0016] The epoxy emulsifier is one or more of Solvay 0092 emulsifier, Juntu JT802 emulsifier, Baiyuan Chemical BY-3502 emulsifier, Guangtong BH600 emulsifier, Xiaohe XE1050 emulsifier and Dow DOWFAX 3A1 emulsifier.

[0017] Preferably, in the preparation of the phenolic epoxy emulsion, the stirring speed is 1000-3000 r / min and the stirring time is 20-40 min.

[0018] Preferably, in the preparation of the calcium phosphate oligomer, the stirring speed of the added triethylamine is 500-1500 r / min and the stirring time is 20-40 min; the centrifugation speed is 6000-8000 r / min and the time is 2-5 min; the washing is with ethanol.

[0019] Preferably, the epoxy curing agent is one or more of Huntsman 38-1, Wanhua SCA-8325, Wanhua 338, Wanhua HT600, Rich 2283, Rich 8006, Rich 8041, Lianggu 919, Lianggu 920, Lianggu 936, Balin Petrochemical CYDHD, EPIKURE 8193 and Yingchuang 2280.

[0020] The defoaming agent is one or more of AKN 3386, EGO-8030, KMT-2033, Castle-2223 and Weichuang W-604.

[0021] The preparation method of the transparent anticorrosive phenolic epoxy varnish is characterized by comprising the following steps:

[0022] 1) The phenolic epoxy emulsion is prepared by heating the phenolic epoxy resin, long carbon chain alkyl compound, epoxy emulsifier and organic solvent to 110-130°C to melt and then mix uniformly, cooling to 80-110°C, and then adding water dropwise under stirring for 20-40 min;

[0023] 2) The calcium chloride dihydrate and anhydrous ethanol A are mixed at room temperature to form a clear solution, then triethylamine is added and stirred, and then the mixed and uniform phosphoric acid and anhydrous ethanol B are added and stirred at room temperature for 8-14 hours, centrifuged and washed to obtain the calcium phosphate oligomer;

[0024] 3) Mix the phenolic aldehyde epoxy emulsion, phosphoric acid oligomer gel and water uniformly, add the epoxy curing agent and defoaming agent to mix uniformly to obtain the transparent anticorrosive phenolic aldehyde epoxy varnish.

[0025] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0026] 1) The present application prepares calcium phosphate oligomers with polymerization characteristics of organic matter, and the calcium phosphate oligomers are added to the curing process of the epoxy resin. The calcium phosphate oligomers can self-polymerize into phosphate clusters, and hydrogen bonds are formed between the phosphate groups and the hydroxyl groups in the coating resin to achieve crosslinking, thereby realizing homogeneous and continuous inorganic phase and organic resin at the molecular level, eliminating the interface between the two substances, greatly improving the corrosion resistance of the waterborne phenolic aldehyde epoxy resin coating, and maintaining the transparency of the paint film.

[0027] 2) The present application utilizes the hydrophobicity of the long carbon chain in the long carbon chain alkyl acid or long carbon chain alkyl amide molecule, and the long carbon chain alkyl acid or long carbon chain alkyl amide is emulsified with the epoxy emulsifier to reduce the use of the epoxy emulsifier and reduce the influence of the hydrophilicity of the emulsifier on the coating film performance, thereby greatly improving the corrosion resistance of the coating.

[0028] 3) The high-performance transparent anticorrosive phenolic aldehyde epoxy varnish of the present application has excellent acid resistance, alkali resistance, salt water resistance and salt mist resistance, and can be applied to the varnish anticorrosion field of metal and furniture wood. DETAILED DESCRIPTION

[0029] In order to better understand the present application, the following embodiments are further described, but the scope of protection required by the present application is not limited to the scope expressed by the embodiments.

[0030] The coating film obtained in each embodiment of the present application is tested according to the following standards.

[0031] Hardness: GB / T 6379-2022;

[0032] Adhesion: GB / T 9286-2021;

[0033] Salt water resistance: GB / T 9274-1988;

[0034] Acid and alkali resistance: GB / T 9274-1988;

[0035] Salt mist resistance: GB / T 1771-2007;

[0036] The transparent anticorrosive phenolic aldehyde epoxy varnish is prepared by uniformly mixing phenolic aldehyde epoxy emulsion, calcium phosphate oligomer, water, epoxy curing agent and defoaming agent; the phenolic aldehyde epoxy emulsion is prepared by uniformly mixing phenolic aldehyde epoxy resin, long carbon chain alkyl compound, epoxy emulsifier and organic solvent after melting at 110-130 DEG C, cooling to 80-110 DEG C and adding water dropwise under stirring for 20-40 min; the long carbon chain alkyl compound is long carbon chain alkyl acid or long carbon chain alkyl amide; the calcium phosphate oligomer is prepared by mixing calcium chloride dihydrate and anhydrous ethanol A under stirring at room temperature to form a clear solution, adding triethylamine under stirring, adding uniformly mixed phosphoric acid and anhydrous ethanol B under stirring at room temperature, stirring for 8-14 hours, centrifuging and washing.

[0037] The application can reduce the use of epoxy emulsifier and the influence of epoxy emulsifier on coating film performance by using long carbon chain alkyl compound to assist emulsification, and can realize the copolymerization of organic epoxy resin, curing agent and inorganic calcium phosphate by preparing calcium phosphate oligomer with polymerization characteristics and adding the calcium phosphate oligomer into the curing process of the epoxy resin, so that the calcium phosphate oligomer can self-polymerize into phosphate clusters, the phosphate can form hydrogen bond with the hydroxyl in the coating resin to realize crosslinking, the inorganic phase and the organic resin can realize homogeneous and continuous phase at the molecular level, the interface between the two substances is eliminated, the continuous and uniform transparent coating film is obtained, and the hardness, adhesion, alkali resistance and salt water resistance of the coating are greatly improved.

[0038] It should be noted that the inorganic material is usually crystallized to produce nano or microparticle level solid powder, but does not have a continuous structure. The high molecular organic material is easy to be molded and manufactured to produce a film with a continuous structure. The phosphate is an important environment-friendly anticorrosive pigment with a strong anticorrosion effect, and is usually added as a filler in the coating. The phosphate releases phosphate ions after hydrolysis, and forms a chelate with metal ions, which covers the surface of the metal material as a protective film to hinder the corrosion of the metal by the corrosion environment. However, the phosphate pigment generally has a large particle size, and the inorganic and organic components are completely different in the forming way, so they cannot be completely compatible, and there is always a gap between the interfaces, which becomes the attack point of the corrosion particles. Even if the phosphate is reduced to nano size, it cannot form a continuous and homogeneous structure with the organic resin, which causes defects in the coating film and makes the coating opaque.

[0039] The calcium phosphate oligomer of the application is a low polymer with polymerization characteristics capped by triethylamine [(Ca3(PO4)2]n m (C6H 15 N) n, m is about 3-6, and n is about 2-3. The transparent anticorrosive phenolic epoxy varnish of the present application effectively combines the phenolic epoxy emulsion and the calcium phosphate oligomer. When the calcium phosphate oligomer is added to the mixture of the epoxy emulsion and the curing agent, the organic-inorganic copolymerization is carried out during curing, the calcium phosphate and the epoxy coating form a homogeneous continuous copolymer, the interface between the organic phosphate and the inorganic epoxy coating is eliminated, and the mechanical properties and the chemical resistance of the epoxy coating are greatly improved. The main equation of the copolymerization reaction is as follows:

[0040]

[0041] wherein m is 3-6, n is 2-3, and z>m:

[0042] It can be seen that during the curing process of the epoxy resin, the calcium phosphate oligomer can self-polymerize into phosphate clusters, and the phosphate groups can form hydrogen bonds with the hydroxyl groups in the coating resin to realize crosslinking and organic-inorganic copolymerization, so that a uniform transparent coating with high strength and good chemical resistance is prepared, which can be used for varnish protection and can provide good protection for metals and wooden furniture.

[0043] Example 1:

[0044] (1) Preparation of calcium phosphate oligomer

[0045] 2g of CaCl2·2H2O was dissolved in 350g of ethanol to form a clear calcium chloride solution. 18g of triethylamine was added to the above solution, and the mixture was stirred at room temperature for 20 minutes to obtain a calcium chloride triethylamine solution. 1.5g of H3PO4 was dissolved in 50g of ethanol to prepare a phosphoric acid solution. The prepared phosphoric acid solution was added dropwise to the calcium chloride triethylamine solution through a peristaltic pump, and the mixture was stirred at room temperature for 12 hours to obtain a calcium phosphate oligomer ethanol solution. The calcium phosphate oligomer gel was obtained by high-speed centrifugation at 8000r / min for 3 minutes, and the gel was washed several times with ethanol to remove excess triethylamine, thereby obtaining the calcium phosphate oligomer gel.

[0046] (2) Preparation of phenolic epoxy emulsion

[0047] 40g of o-cresol formaldehyde epoxy resin, 2g of oleic acid amide, 8g of ethylene glycol butyl ether and 10g of epoxy emulsifier were heated to 100℃ and uniformly mixed, then the temperature was lowered to 100℃, and 50g of water was added dropwise at a stirring speed of 2500r / min for 30 minutes to obtain a transparent anticorrosive phenolic epoxy emulsion.

[0048] The obtained emulsion was stable after storage for 3 months, and no layering was observed after centrifugation at 3500r / min for 30 minutes.

[0049] (3) Preparation of phenolic epoxy varnish

[0050] Take 10 g of prepared o-cresol formaldehyde epoxy emulsion, 2.5 g of deionized water, 1 g of prepared calcium phosphate oligomer gel, stir for 15 min, mix evenly, then add 1 g of Huntsman 38-1 curing agent, 0.1 g of AKN3386 defoamer and mix evenly to obtain transparent anticorrosive phenolic aldehyde epoxy varnish.

[0051] Example 2:

[0052] (1) Preparation of calcium phosphate oligomer

[0053] Dissolve 3 g of CaCl2·2H2O in 350 g of ethanol to form a clear calcium chloride solution. Add 18 g of triethylamine to the above solution and stir at room temperature for 30 min to fully mix to obtain a calcium chloride triethylamine solution. Dissolve 5 g of H3PO4 in 50 g of ethanol to prepare a phosphoric acid solution. Add the prepared phosphoric acid solution dropwise to the calcium chloride triethylamine solution through a peristaltic pump, stir at room temperature for 8 h to obtain a calcium phosphate oligomer ethanol solution, and centrifuge at 7000 r / min for 3 min to obtain a calcium phosphate oligomer gel. Wash several times with ethanol to remove excess triethylamine to obtain a calcium phosphate oligomer gel.

[0054] (2) Preparation of phenolic aldehyde epoxy emulsion

[0055] Heat 50 g of o-cresol formaldehyde epoxy resin, 4 g of oleic acid, 10 g of ethylene glycol butyl ether and 12 g of epoxy emulsifier to 110°C, melt and mix evenly, cool to 90°C, and add 60 g of water dropwise at a stirring speed of 3000 r / min for 20 min to obtain a transparent anticorrosive phenolic aldehyde epoxy emulsion.

[0056] The obtained emulsion is stable after standing for 3 months, and does not separate after centrifugation at 3500 r / min for 30 min.

[0057] (3) Preparation of phenolic aldehyde epoxy varnish

[0058] Take 10 g of prepared o-cresol formaldehyde epoxy emulsion, 2.5 g of deionized water, 2 g of prepared calcium phosphate oligomer gel, stir for 10 min, mix evenly, then add 1.25 g of Wanhua SCA-8325 curing agent, 0.1 g of EGO-8030 defoamer and mix evenly to obtain transparent anticorrosive phenolic aldehyde epoxy varnish.

[0059] Example 3:

[0060] (1) 2 g CaCl2.2H2O was dissolved in 300 g of ethanol to form a clear calcium chloride solution. 18 g of triethylamine was added to the solution, which was stirred at room temperature for 10 minutes to form a calcium chloride triethylamine solution. 5 g of H3PO4 was dissolved in 30 g of ethanol to form a phosphoric acid solution. The prepared phosphoric acid solution was added dropwise to the calcium chloride triethylamine solution by using a peristaltic pump, and stirred at room temperature for 8 hours to obtain a calcium phosphate oligomer ethanol solution. The solution was centrifuged at a high speed of 6000 r / min for 3 minutes to obtain a calcium phosphate oligomer gel, which was washed several times with ethanol to remove excess triethylamine, thereby obtaining a calcium phosphate oligomer gel.

[0061] (2) Preparation of a phenolic epoxy emulsion

[0062] 60 g of bisphenol A phenolic epoxy resin, 1 g of stearic acid, 12 g of propylene glycol methyl ether, and 14 g of an epoxy emulsifier were heated to 120°C to melt and mix uniformly, and then cooled to 80°C. 70 g of water was added dropwise at a stirring speed of 1000 r / min for 40 minutes to obtain a transparent anticorrosive phenolic epoxy emulsion.

[0063] The obtained emulsion was stable after being stored for 3 months, and was not separated after being centrifuged at 3500 r / min for 30 minutes.

[0064] (3) Preparation of a phenolic epoxy varnish

[0065] 10 g of the prepared bisphenol A phenolic epoxy emulsion, 2.5 g of deionized water, and 2 g of the prepared calcium phosphate oligomer gel were stirred for 15 minutes to mix uniformly, and then 1.5 g of Wanhua 338 curing agent and 0.1 g of KMT-2033 defoaming agent were added to mix uniformly, thereby obtaining a transparent anticorrosive phenolic epoxy varnish.

[0066] Example 4:

[0067] (1) 3 g of CaCl2.2H2O was dissolved in 400 g of ethanol to form a clear calcium chloride solution. 15 g of triethylamine was added to the solution, which was stirred at room temperature for 20 minutes to form a calcium chloride triethylamine solution. 3 g of H3PO4 was dissolved in 30 g of ethanol to form a phosphoric acid solution. The prepared phosphoric acid solution was added dropwise to the calcium chloride triethylamine solution by using a peristaltic pump, and stirred at room temperature for 8 hours to obtain a calcium phosphate oligomer ethanol solution. The solution was centrifuged at a high speed of 7000 r / min for 3 minutes to obtain a calcium phosphate oligomer gel, which was washed several times with ethanol to remove excess triethylamine, thereby obtaining a calcium phosphate oligomer gel.

[0068] (2) Preparation of a phenolic epoxy emulsion

[0069] Heat 40 g of bisphenol A novolac epoxy resin, 3 g of oleic acid, 14 g of propylene glycol methyl ether and 8 g of epoxy emulsifier to 130 °C to melt and mix evenly, cool to 60 °C, add 40 g of water dropwise at a stirring speed of 1500 r / min for 20 min to obtain a transparent anticorrosive novolac epoxy emulsion.

[0070] The obtained emulsion is stable after standing for 3 months, and does not separate after centrifugation at 3500 r / min for 30 min.

[0071] (3) Preparation of novolac epoxy varnish

[0072] Take 10 g of the prepared bisphenol A novolac epoxy emulsion, 4 g of deionized water, 3 g of the prepared calcium phosphate oligomer gel, stir for 15 min, mix evenly, then add 2 g of Wanhua HT600 curing agent, mix evenly, and add 0.1 g of Weichuang W-604 defoaming agent to obtain a transparent anticorrosive novolac epoxy varnish.

[0073] Example 5:

[0074] (1) Dissolve 2 g of CaCl2·2H2O in 500 g of ethanol to form a clear calcium chloride solution. Add 20 g of triethylamine to the above solution, stir at room temperature for 40 min, and mix thoroughly to obtain a calcium chloride triethylamine solution. Dissolve 5 g of H3PO4 in 60 g of ethanol to prepare a phosphoric acid solution. Add the prepared phosphoric acid solution dropwise to the calcium chloride triethylamine solution through a peristaltic pump, stir at room temperature for 8 h, and obtain a calcium phosphate oligomer ethanol solution. Centrifuge at a high speed of 8000 r / min for 3 min to obtain a calcium phosphate oligomer gel. Wash with ethanol several times to remove excess triethylamine, and obtain the calcium phosphate oligomer gel.

[0075] (2) Preparation of novolac epoxy emulsion

[0076] Heat 50 g of phenol novolac epoxy resin, 1 g of oleic acid amide, 16 g of acetylacetone and 8 g of epoxy emulsifier to 130 °C to melt and mix evenly, cool to 70 °C, add 60 g of water dropwise at a stirring speed of 3000 r / min for 40 min to obtain a transparent anticorrosive novolac epoxy emulsion.

[0077] The obtained emulsion is stable after standing for 3 months, and does not separate after centrifugation at 3500 r / min for 30 min.

[0078] (3) Preparation of novolac epoxy varnish

[0079] Take 10 g of the prepared phenol novolac epoxy emulsion, 2.5 g of deionized water, 2 g of the prepared calcium phosphate oligomer gel, stir for 15 min, mix evenly, then add 1 g of Rich 2283 curing agent, and 0.1 g of Castle-2223 defoaming agent to obtain a transparent anticorrosive novolac epoxy varnish.

[0080] Example 6:

[0081] (1) 3 g of CaCl2.2H2O was dissolved in 350 g of ethanol to form a clear calcium chloride solution. 18 g of triethylamine was added to the solution and stirred at room temperature for 30 min to form a calcium chloride triethylamine solution. 5 g of H3PO4 was dissolved in 50 g of ethanol to form a phosphoric acid solution. The prepared phosphoric acid solution was added dropwise to the calcium chloride triethylamine solution by using a peristaltic pump and stirred at room temperature for 15 h to obtain a calcium phosphate oligomer ethanol solution. The solution was centrifuged at 6000 r / min for 3 min to obtain a calcium phosphate oligomer gel, which was washed with ethanol several times to remove excess triethylamine, thereby obtaining a calcium phosphate oligomer gel.

[0082] (2) Preparation of a phenolic aldehyde epoxy emulsion

[0083] 60 g of a phenolic aldehyde epoxy resin, 2 g of an oleic acid amide, 18 g of diacetone alcohol, and 10 g of an epoxy emulsifier were heated to 130°C and uniformly mixed. The temperature was lowered to 60°C, and 50 g of water was added dropwise at a stirring speed of 2000 r / min for 10 min to obtain a transparent anticorrosive phenolic aldehyde epoxy emulsion.

[0084] (3) Preparation of a phenolic aldehyde epoxy varnish

[0085] The obtained emulsion was stored for 3 months and was stable without separation after centrifugation at 3500 r / min for 30 min.

[0086] 10 g of the prepared phenolic aldehyde epoxy emulsion, 2.5 g of deionized water, and 1 g of the prepared calcium phosphate oligomer gel were stirred for 15 min, uniformly mixed, and then 2 g of the curing agent Rieck 8006 and 0.1 g of the defoaming agent Weicheng W-604 were added and uniformly mixed to obtain a transparent anticorrosive phenolic aldehyde epoxy varnish.

[0087] Comparative Example 1:

[0088] (1) Preparation of a phenolic aldehyde epoxy emulsion

[0089] 60 g of a phenolic aldehyde epoxy resin, 18 g of diacetone alcohol, and 12 g of an epoxy emulsifier were heated to 130°C and uniformly mixed. The temperature was lowered to 60°C, and 50 g of water was added dropwise at a stirring speed of 2000 r / min for 10 min to obtain a high-phenolic aldehyde epoxy emulsion.

[0090] The obtained emulsion was stored for 3 months and was stable without separation after centrifugation at 3500 r / min for 30 min.

[0091] (2) Preparation of a phenolic aldehyde epoxy varnish

[0092] Take 10 g of the prepared phenol type phenolic epoxy emulsion, 2.5 g of deionized water, mix evenly, then add 2 g of Rich 8006 curing agent, 0.1 g of Weicheng W-604 defoamer and mix evenly to obtain a phenolic epoxy varnish.

[0093] Comparative Example 2:

[0094] (1) Preparation of phenolic epoxy emulsion

[0095] Heat 60 g of phenol type phenolic epoxy resin, 2 g of oleic acid amide, 18 g of diacetone alcohol and 10 g of epoxy emulsifier to 130℃ and melt mix evenly, cool to 60℃, add 50 g of water at a stirring speed of 2000 r / min for 10 min to obtain a phenolic epoxy emulsion.

[0096] The obtained emulsion is stable after standing for 3 months, and does not separate after centrifugation at 3500 r / min for 30 min.

[0097] (2) Preparation of phenolic epoxy varnish

[0098] Take 10 g of the prepared phenol type phenolic epoxy emulsion, 2.5 g of deionized water, mix evenly, then add 2 g of Rich 8006 curing agent, 0.1 g of Weicheng W-604 defoamer and mix evenly to obtain a phenolic epoxy varnish.

[0099] The phenolic epoxy varnish obtained in the above Examples 1-6 is coated on the tinplate cleaned with ethanol and water using a film applicator, with a film dry thickness of about 50 μm, and the coating performance is tested after drying at room temperature for 14 days. The test results are shown in Table 1.

[0100] Table 1: Cured coating performance of transparent anticorrosive phenolic epoxy emulsion

[0101]

[0102] As can be seen from the results in Table 1, the coatings prepared by using long-chain alkyl acid or long-chain alkyl amide assisted emulsion and adding calcium phosphate oligomer in Examples 1-6 have high hardness, good adhesion, and good resistance to alkali, salt water and salt mist. Coating is the simplest and most effective method to protect metals and wood from corrosion, and the main function of the coating is basically to protect the easily corroded materials. The first three indicators in Table 1 can be met by general varnish, and the last four performances generally require the addition of various anticorrosive fillers to achieve such a level, but the addition of anticorrosive fillers is in the preparation stage of the coating, and the addition of fillers will make the coating become opaque. The present application improves the corrosion resistance of the coating while meeting the transparency of the coating, and can be effectively used for varnish protection of metals and wood.

[0103] The epoxy emulsion of the comparative example 1 is prepared without the aid of oil acid emulsification and without the addition of calcium phosphate oligomer during the preparation of the varnish. The epoxy emulsion of the comparative example 2 is prepared with the aid of oil acid emulsification and without the addition of calcium phosphate oligomer during the preparation of the varnish. By comparing the comparative example 1 and the comparative example 2, the use of oil acid and epoxy emulsifier can reduce the use of epoxy emulsifier, and the performance of the coating film prepared by the emulsion is obviously improved compared with the coating film prepared by the emulsion without the aid of oil acid emulsification. The acid resistance, alkali resistance, salt water resistance and salt spray resistance are obviously improved, and the influence of epoxy emulsifier on the performance of the coating film is also reduced. By comparing the comparative example 2 and the example 6, it can be shown that the calcium phosphate oligomer can improve the performance of the coating. By using the emulsion with the aid of oil acid amide emulsification, the use of epoxy emulsifier is reduced, and the hardness and adhesion of the cured coating film (comparative example 2) are not changed, but the acid resistance, alkali resistance, salt water resistance and salt spray resistance are improved. By comparing the comparative example 2 and the example 6, the addition of calcium phosphate oligomer can self-aggregate into calcium phosphate clusters during the curing process, and the phosphate groups can form hydrogen bonds with the hydroxyl groups in the coating resin to realize cross-linking, realizing the homogeneous system of inorganic phase and organic resin at the molecular level. The addition of inorganic calcium phosphate can improve the strength of the coating film, increase the hardness, the phosphate groups can react with the metal substrate to improve the adhesion of the coating, and the calcium ions can adsorb and intercept the negative particles in the solution to improve the alkali resistance, salt water resistance and salt spray resistance of the coating. By comparing the comparative example 1 and the example 6, the varnish prepared by the emulsion with the aid of long carbon chain alkyl acid (amide) emulsification and the addition of calcium phosphate oligomer during the preparation of the varnish can reduce the negative influence of epoxy emulsifier on the performance of the coating film, and the addition of calcium phosphate oligomer as an additive can improve the performance of the coating film. The combination of the two can make the performance of the waterborne phenolic epoxy varnish better.

[0104] The application adds the calcium phosphate oligomer with polymer characteristics into the varnish preparation process, realizes organic-inorganic copolymerization, eliminates the boundary between the organic phase and the inorganic phase on the one hand, and obtains a uniform transparent coating; on the other hand, the obtained organic-inorganic homogeneous coating eliminates the interface gap between the inorganic filler and the organic resin, improves the physical barrier effect of the coating, and makes the coating film have certain inorganic strength, improves the hardness and adhesion of the coating; especially the calcium phosphate oligomer in the low dielectric constant alcohol solution is capped by triethylamine through hydrogen bond. The calcium phosphate oligomer is added into the phenolic epoxy curing system, and with the volatilization of triethylamine, self-polymerization is carried out, the phenolic epoxy resin and the curing agent are crosslinked to produce hydroxyl, the phosphate can form hydrogen bond with the hydroxyl to realize crosslinking, complete organic-inorganic copolymerization, and obtain a uniform and continuous calcium phosphate / phenolic epoxy coating. In this way, the calcium phosphate is uniformly distributed in the varnish in the varnish preparation stage, and the comprehensive corrosion resistance is significantly improved. Mainly because the long carbon chain alkyl acid or long carbon chain alkyl amide compound emulsification can reduce the negative influence of the epoxy emulsifier on the film performance, the calcium phosphate oligomer as an additive can improve the film performance, and the combination of the two can improve the performance of the water-based phenolic epoxy varnish.

Claims

1. A transparent anticorrosive novolak epoxy clear coating characterized by, The phenolic epoxy emulsion, calcium phosphate oligomer, water, epoxy curing agent and defoaming agent are mixed and uniformly reacted to obtain; The phenolic epoxy emulsion is obtained by uniformly mixing phenolic epoxy resin, long carbon chain alkyl compound, epoxy emulsifier and organic solvent after melting at 110-130 DEG C, cooling to 80-110 DEG C and adding water dropwise under stirring for 20-40 min; the long carbon chain alkyl compound is long carbon chain alkyl acid or long carbon chain alkyl amide, and the number of carbon atoms is 16-22; The calcium phosphate oligomer is obtained by mixing calcium chloride dihydrate and anhydrous ethanol A at room temperature to form a clear solution, adding triethylamine and stirring, adding mixed and uniformly mixed phosphoric acid and anhydrous ethanol B, stirring at room temperature for 8-14 hours, centrifuging and washing; In the preparation of the phenolic epoxy varnish, the phenolic epoxy emulsion is 40-90 parts, the calcium phosphate oligomer is 10-30 parts, the water is 10-20 parts, the epoxy curing agent is 10-30 parts and the defoaming agent is 1-4 parts by mass.

2. The transparent anticorrosive novolak epoxy varnish according to claim 1, characterized by, In the preparation of the phenolic epoxy emulsion, the phenolic epoxy resin is 30-90 parts, the long carbon chain alkyl compound is 2-30 parts, the organic solvent is 4-10 parts, the epoxy emulsifier is 2-40 parts and the water is 20-60 parts by mass.

3. The clear anticorrosive novolak epoxy varnish according to claim 1, characterized by, In the preparation of the calcium phosphate oligomer, the calcium chloride dihydrate is 0.3-5 parts, the anhydrous ethanol A is 50-90 parts, the triethylamine is 4-10 parts, the phosphoric acid is 0.1-5 parts and the anhydrous ethanol B is 3-20 parts by mass.

4. The transparent anticorrosive novolak epoxy varnish according to claim 1 or 2, characterized by: In the preparation of the phenolic epoxy emulsion, the long carbon chain alkyl compound is one or more of oleic acid, stearic acid, myristic acid, palmitoleic acid, oleic acid amide and oleic acid-based palmitic acid amide; the phenolic epoxy resin is one or more of o-cresol epoxy resin, bisphenol A phenolic epoxy resin and phenol type phenolic epoxy resin.

5. The clear, anticorrosive, phenalkamine epoxy varnish of claim 1, wherein: In the preparation of the phenolic epoxy emulsion, the organic solvent is one or more of ethylene glycol butyl ether, propylene glycol methyl ether, diacetone alcohol, acetylacetone, N-methyl pyrrolidine and diethylene glycol butyl ether; The epoxy equivalent weight of the phenolic epoxy resin is 160-250 g / eq.

6. The clear, anticorrosive, phenalkamine epoxy varnish of claim 1, wherein: In the preparation of the phenolic epoxy emulsion, the stirring speed is 1000-3000 r / min, and the stirring time is 20-40 min.

7. The transparent anticorrosive novolak epoxy varnish according to claim 1, characterized by: In the preparation of the calcium phosphate oligomer, the stirring speed of adding triethylamine is 500-1500 r / min, and the stirring time is 20-40 min; the centrifuging speed is 6000-8000 r / min, and the time is 2-5 min; The washing is washing with ethanol.

8. The process for the preparation of the transparent anticorrosive novolak epoxy varnish according to claim 1, characterized in that The method comprises the following steps: 1) uniformly mixing phenolic epoxy resin, long carbon chain alkyl compound, epoxy emulsifier and organic solvent after melting at 110-130 DEG C, cooling to 80-110 DEG C and adding water dropwise under stirring for 20-40 min to obtain phenolic epoxy emulsion; 2) mixing calcium chloride dihydrate and anhydrous ethanol A at room temperature to form a clear solution, adding triethylamine and stirring, adding mixed and uniformly mixed phosphoric acid and anhydrous ethanol B, stirring at room temperature for 8-14 hours, centrifuging and washing to obtain calcium phosphate oligomer; 3) mixing the phenolic epoxy emulsion, calcium phosphate oligomer and water uniformly, adding the epoxy curing agent and defoaming agent to mix uniformly to obtain the transparent anticorrosive phenolic epoxy varnish.

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