Emulsion type phenolic aldehyde amine epoxy curing agent and preparation method thereof

Abstract

The invention relates to the technical field of emulsion type epoxy hardeners, and particularly discloses an emulsion type phenolic aldehyde amine epoxy hardener and a preparation method thereof. A preparation method of an emulsion type phenolic aldehyde amine epoxy curing agent comprises the following steps: S1, adding a catalyst and epoxy resin into polyether polyol, heating to 120-180 DEG C, reacting for 3-6 hours, cooling to 50-80 DEG C, and adding a solvent for dilution to obtain a prepolymer A; s2, adding epoxy-terminated polyether into phenolic aldehyde amine, and reacting at 60-85 DEG C to obtain a prepolymer B; and S3, blending the prepolymer A and the prepolymer B, reacting at 40-80 DEG C for 2-4 hours, and then adding water to react for 0.5-1 hour, thereby obtaining the product. The emulsion type phenolic aldehyde amine epoxy curing agent has the advantages that the emulsion type phenolic aldehyde amine epoxy curing agent is not prone to layering after being placed for a long time, the storage stability is excellent, the curing agent can be used for blending curing with epoxy resin emulsion, and the performance of a cured paint film is excellent.

Description

Technical Field

[0001] The present application relates to the technical field of epoxy curing agents, and more specifically, to an emulsion-type phenolic amine epoxy curing agent and a preparation method thereof. Background Art

[0002] With the increasing awareness of environmental protection, solvent-based epoxy coatings with high VOC and flammability will gradually be eliminated from the market. Accordingly, water-based epoxy coatings with environmental friendliness, safe production and construction, no (low) toxicity, easy equipment cleaning, and good permeability will be more and more widely used in the coating industry.

[0003] Epoxy resin needs to be used with curing agent to have practical application value. There are many types of curing agents. Combining the trend of epoxy resin becoming water-based, giving curing agent emulsification function to make it a water-based epoxy resin system is a current research hotspot. In addition to the cross-linking and curing effect, this water-based curing agent also plays the role of emulsifying epoxy resin. Water-based curing agents are divided into water-soluble and emulsion types. Water-soluble curing agents are more commonly used on the market, but the hydrophilic group content of water-soluble curing agents is high, which is easy to have an adverse effect on the performance of the later paint film, and the long hydrophilic chain segment is easy to cause the curing agent to have excessive viscosity, poor stability, poor water resistance of the paint film and other adverse effects, and the operating time is not long enough; while the emulsion type curing agent has good compatibility with epoxy emulsion, the emulsion type curing agent has good compatibility with water-based epoxy resin, is easy to dilute, and the paint film dries quickly. Under the control of the appropriate amount of emulsifier, a cured paint film with good resistance can be obtained, but the storage stability of the emulsion type curing agent is not ideal. Summary of the invention

[0004] In order to improve the storage stability of an emulsion curing agent, the present application provides an emulsion phenolic amine epoxy curing agent and a preparation method thereof.

[0005] In the first aspect, the present application provides a method for preparing an emulsion-type phenolic amine epoxy curing agent, using the following technical solution: An emulsion type phenalkamine epoxy curing agent comprises the following steps: S1. Add a catalyst and an epoxy resin to a polyether polyol, raise the temperature to 120-180°C for reaction for 3-6 hours, cool to 50-80°C, and then add a solvent for dilution to obtain a prepolymer A; S2, adding epoxy-terminated polyether to phenolic amine, reacting at 60-85° C. to obtain prepolymer B; S3, prepolymer A and prepolymer B are mixed, reacted at 40-80°C for 2-4h, and then water is added to react for 0.5-1h to obtain.

[0006] By adopting the above technical solution: introducing polyether segments, phenolic segments and long carbon segments into the curing agent, while ensuring good compatibility between the curing agent and the epoxy emulsion, the flexibility and durability of the coating are increased, and rapid curing can be achieved under normal or low temperature conditions, while providing a longer operating period, which is beneficial to the working environment with a short construction period or repeated coating in a short period of time.

[0007] Using epoxy-terminated polyether chain extension: It can not only increase the molecular weight of the curing agent and its compatibility with epoxy resin, but also significantly improve the toughness and mechanical properties of the paint film while maintaining the transparency of the material. Compared with other chain extensions, such as epoxy resin 6101 chain extension, the product stability is poor and the product is easy to delaminate.

[0008] Optionally, in step S1, the weight ratio of polyether polyol, catalyst and epoxy resin is (83.5-100):(0.28-0.33):10.

[0009] By adopting the above technical solution: when the weight ratio of the polyether polyol, the catalyst and the epoxy resin is within the above range, the paint film performance is optimal after the prepared curing agent is blended and cured with the epoxy resin emulsion to form a film.

[0010] Optionally, the number average molecular weight of the polyether polyol is 500-10000; The epoxy resin is bisphenol A epoxy resin; The catalyst is triphenylphosphine or boron trifluoride; The solvent is propylene glycol methyl ether.

[0011] Optionally, in step S2, the preparation method of phenalkamine is: Phenols are added to the base amine, aldehydes are added at 50-80°C, the mixture is reacted at 75-95°C for 2.5 hours, and then vacuum dehydration is performed to obtain phenolic amine.

[0012] By adopting the above technical scheme: adding phenolic substances to the base amine, and then adding aldehyde substances for condensation reaction, obtaining phenolic amine after the reaction is complete, and subsequently reacting with terminal epoxy polyether for chain extension, the emulsion is guaranteed to have a long storage period and no stratification during long-term storage.

[0013] Optionally, the weight ratio of the base amine, phenols and aldehydes is (58-63.2):(47-150):15.

[0014] By adopting the above technical scheme: when the weight ratio of the basic amine, phenols and aldehydes is within the above range, the prepared curing agent has a long storage period and no stratification, and the paint film formed after being added to the epoxy resin emulsion and cured has better performance.

[0015] Optionally, the weight ratio of the added amount of the terminal hydroxyl polyether to the aldehyde is 156:15.

[0016] Optionally, the number average molecular weight of the epoxy-terminated polyether is ≤1000.

[0017] By adopting the above technical solution: when a terminal epoxy polyether with a larger molecular weight is used, the water resistance of the prepared paint film is poor.

[0018] Optionally, the base amine is one or more of ethylenediamine, 1,3-propylenediamine, 1,4-butylenediamine, 1,5-pentanediamine, 2-methylpentanediamine, 1,6-hexanediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, polyethyleneimine, 1,6-cyclohexanediamine, diethyltoluenediamine, isophoronediamine, p-xylylenediamine, and m-xylylenediamine; The phenols are one or two of phenol, cardanol, tert-butylphenol and nonylphenol; The aldehyde is formaldehyde or paraformaldehyde.

[0019] By adopting the above technical solution: the preparation method of the present application has relatively low requirements for basic amines, phenols and aldehydes, and the above substances can be used in the preparation method of the present application.

[0020] Optionally, the weight ratio of the prepolymer A to the prepolymer B is (15-20):(132-187.1).

[0021] In a second aspect, the present application provides an emulsion-type phenolic amine epoxy curing agent, which adopts the following technical scheme: an emulsion-type phenolic amine epoxy curing agent, prepared by the above-mentioned preparation method, the solid content of the curing agent is 40-60%, and the theoretical active hydrogen equivalent is 310-333g / Eq.

[0022] By adopting the above technical solution, the viscosity is low and the active hydrogen equivalent is high.

[0023] In summary, this application has the following beneficial effects: 1. The curing agent of the present application introduces polyether segments, phenolic segments and long carbon segments, and utilizes hydroxyl-containing phenol to improve the compatibility of the curing agent and epoxy emulsion, thereby increasing the flexibility and durability of the coating film, and can achieve rapid curing at room temperature or low temperature conditions, while providing a longer operating period, which is beneficial to a short construction period or an operating environment that requires coating in a short time; in particular, the end-terminated epoxy polyether allows the prepared curing agent to be stored for a long time without stratification; 2. The curing agent of this application has low viscosity, which makes the construction more convenient. It is also suitable for environmentally friendly materials with high VOC content and thick coating. DETAILED DESCRIPTION

[0024] The present application is further described in detail below in conjunction with the examples. The sources of the components are as follows, except for the following special instructions, the components are commercially available: Epoxy resin E-20, sourced from Nantong Xingchen Synthetic Materials Co., Ltd.; Polypropylene glycol glycidyl ether, purchased from Anhui Xinyuan Technology Co., Ltd., model XY207; Phenol, sourced from Shandong Chuangying Chemical Co., Ltd.; Tert-butylphenol, obtained from Shandong Chuangying Chemical Co., Ltd.; Nonylphenol, sourced from Jiangsu Lingfei Technology Co., Ltd.; Cardanol, collected from Nanjing Jinhaiwei New Materials Co., Ltd.; Paraformaldehyde was obtained from Shandong Chuangying Chemical Co., Ltd.

[0025] Example 1 An emulsion type phenolic amine epoxy curing agent is prepared by the following steps: S1. Add 0.28 g of triphenylphosphine catalyst to 83.5 g of polyether polyol (poloxamer, BASF F68), heat and stir to mix, add 10 g of epoxy resin E-20 dropwise, heat to 120 ° C and react for 6 h, cool to 50 ° C and add 23.4 g of solvent (propylene glycol methyl ether) to dilute to 80% solid content, cool to room temperature, and obtain prepolymer A; S2. Add 47 g of phenols (phenol) to 58 g of base amine (1,6-hexanediamine), add 15 g of aldehydes (paraformaldehyde) dropwise at 50° C., react at 75° C. for 2 h, then heat to 95° C. and keep warm for 30 min, vacuum dehydrate for 30 min, then cool to 30° C. to obtain phenolic amine; add 156 g of epoxy-terminated polyether (polypropylene glycol diglycidyl ether, dropping time is 1 h) dropwise to the phenolic amine, react at 65° C. for 2 h, then heat to 85° C. and react for 2 h, to obtain prepolymer B; S3. 15 g of prepolymer A and 132 g of prepolymer B were blended, reacted at 40° C. for 4 h, then cooled to 50° C., and 98 g of deionized water was added at 1500 rpm while stirring and reacted for 0.5 h to obtain the product.

[0026] Example 2 An emulsion type phenolic amine epoxy curing agent is prepared by the following steps: S1. Add 0.28 g of catalyst triphenylphosphine to 83.5 g of polyether polyol (poloxamer, BASF F68), heat and stir to mix, add 10 g of epoxy resin E-20 dropwise, heat to 150 ° C and react for 4 h, cool to 60 ° C and add 23.4 g of solvent (propylene glycol methyl ether) to dilute to 80% solid content, cool to room temperature, and obtain prepolymer A; S2, add 150g of phenols (phenol) to the base amine (58g of 1,6-hexanediamine, 5.2g of diethylenetriamine), add 15g of aldehydes (paraformaldehyde) dropwise at 65°C, react at 90°C for 2h, then heat to 95°C and keep warm for 30min, vacuum dehydrate for 80min and then cool to 50°C to obtain phenalkamine; add 156g of epoxy-terminated polyether (polypropylene glycol diglycidyl ether, dropping time is 1h) dropwise to the phenalkamine, react at 65°C for 2h and then heat to 85°C and react for 2h to obtain prepolymer B; S3, 20g prepolymer A and 187.1g prepolymer B were blended, reacted at 60°C for 3h, then cooled to 50°C, and 136g deionized water was added at 1500rpm while stirring and reacted for 0.5h to obtain the product.

[0027] Example 3 An emulsion type phenolic amine epoxy curing agent is prepared by the following steps: S1. Add 0.33 g of catalyst triphenylphosphine to 100 g of polyether polyol (PEG-10000), heat and stir to mix, dropwise add 10 g of epoxy resin E-20, heat to 180 ° C and react for 3 h, cool to 80 ° C and add 27.6 g of solvent (propylene glycol methyl ether) to dilute to 80% solid content, cool to room temperature, and obtain prepolymer A; S2. Add 47 g of phenol (cardanol) to 58 g of base amine (1,6-hexanediamine), add 15 g of aldehyde (paraformaldehyde) dropwise at 80° C., react at 75° C. for 2 h, then heat to 95° C. and keep warm for 30 min, vacuum dehydrate for 120 min, then cool to 60° C. to obtain phenolic amine; add 156 g of epoxy-terminated polyether (polypropylene glycol diglycidyl ether, dropping time is 1 h) dropwise to the phenolic amine, react at 65° C. for 2 h, then heat to 85° C. and react for 2 h, to obtain prepolymer B; S3. 15 g of prepolymer A and 132 g of prepolymer B were mixed, reacted at 80° C. for 2 h, then cooled to 50° C., and 100 g of deionized water was added while stirring at 1500 rpm and reacted for 1 h to obtain the product.

[0028] Example 4 An emulsion type phenolic amine epoxy curing agent is prepared by the following steps: S1. Add 0.33 g of catalyst boron trifluoride to 100 g of polyether polyol (PPG-500), heat and stir to mix, dropwise add 10 g of epoxy resin E-20, heat to 120 ° C and react for 3 h, cool to 80 ° C and add 27.6 g of solvent (propylene glycol methyl ether) to dilute to 80% solid content, cool to room temperature, and obtain prepolymer A; S2. Add phenols (75 g tert-butylphenol, 75 g nonylphenol) to base amine (58 g 1,3-propylenediamine, 5.2 g diethylenetriamine), dropwise add 15 g aldehydes (formaldehyde) at 55° C., react at 90° C. for 2 h, then heat to 95° C. and keep warm for 30 min, vacuum dehydrate for 30 min and then cool to 50° C. to obtain phenolic amine; dropwise add 156 g epoxy-terminated polyether (polypropylene glycol diglycidyl ether, dropwise addition time is 1 h) to the phenolic amine, first react at 65° C. for 2 h and then heat to 85° C. and react for 2 h to obtain prepolymer B; S3, 20g prepolymer A and 187.1g prepolymer B were blended, reacted at 80°C for 2h, then cooled to 50°C, and 136g deionized water was added at 1500rpm while stirring and reacted for 0.5h to obtain the product.

[0029] Example 5 An emulsion type phenolic amine epoxy curing agent, which is different from Example 1 in that the amount of deionized water added is different, and the amount of deionized water added is 220g.

[0030] Comparative Example 1 An emulsion-type phenolic amine epoxy curing agent is different from Example 1 in that no hydroxyl-terminated polyether is added in step S1.

[0031] Comparative Example 2 An emulsion-type phenolic amine epoxy curing agent is different from Example 1 in that, in step S1, an equal amount of polyethylene glycol M2000 is used instead of the terminal hydroxyl polyether.

[0032] Comparative Example 3 An emulsion type phenolic amine epoxy curing agent, which is different from Example 1 in that the molecular weight of the polyether polyol in step S1 is 3500, and it is purchased from BASF, and the model is Pluronic PE 10100.

[0033] Performance indicators of curing agent The solid content is tested according to GB / T 1725-1979, and the storage stability is tested according to GB / T 20623-2006 (using the centrifugal sedimentation method, 3000rpm / 20min).

[0034] Table 1 Performance indexes of curing agents in examples and comparative examples As shown in Table 1, the curing agents in Examples 1 to 5 have high storage stability and will not delaminate after long-term storage. Comparative Example 1 does not graft polyether, and the storage stability of the curing agent is relatively poor, and delamination will occur after long-term storage.

[0035] Performance Testing The curing agent and epoxy resin emulsion prepared in the examples and comparative examples were blended in a ratio of 1:1 between hydrogen equivalent and epoxy equivalent to obtain a mixed solution. The obtained mixed solution was evenly applied to a tinplate with a scraper to obtain a test plate. The test plate was subjected to the following performance tests, and the test results are recorded in Table 2.

[0036] Detection Methods 1. Determination of drying time: Tested according to GB / T 1728-2020.

[0037] 2. Operational period: Testing shall be carried out in accordance with GB / T 31416-2015.

[0038] 3. Pencil hardness: Tested according to GB / T 6739-2006.

[0039] 4. Adhesion: Tested according to GB / T 9286-2021.

[0040] 5. Impact resistance: Tested according to GB / T 1732-2020.

[0041] 6. Flexibility: Tested according to GB / T 1731-2020.

[0042] 7. Water resistance test: Test according to GB / T 1733-1993 (Method A) and record the time when the surface coating of the test plate begins to bubble and wrinkle.

[0043] Table 2 Performance test results As shown in Table 2, the curing agents of Examples 1-5 are added to the epoxy resin emulsion to form films, and the properties of the films formed are relatively balanced. The curing agents of Comparative Examples 1-3 have insufficient properties after forming films.

[0044] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. An emulsion type phenolic amine epoxy curing agent, characterized in that: The following steps are involved: S1. Add a catalyst and an epoxy resin to a polyether polyol, raise the temperature to 120-180°C for reaction for 3-6 hours, cool to 50-80°C, and then add a solvent for dilution to obtain a prepolymer A; S2, adding epoxy-terminated polyether to phenolic amine, reacting at 60-85° C. to obtain prepolymer B; S3, prepolymer A and prepolymer B are mixed, reacted at 40-80°C for 2-4h, and then water is added to react for 0.5-1h to obtain.

2. The emulsion type phenalkamine epoxy curing agent according to claim 1, characterized in that: In the step S1, the weight ratio of polyether polyol, catalyst and epoxy resin is (83.5-100): (0.28-0.33):

10.

3. An emulsion type phenalkamine epoxy curing agent according to claim 2, characterized in that: The number average molecular weight of the polyether polyol is 500-10000; The epoxy resin is bisphenol A epoxy resin; The catalyst is triphenylphosphine or boron trifluoride; The solvent is propylene glycol methyl ether.

4. The emulsion type phenalkamine epoxy curing agent according to claim 1, characterized in that: In step S2, the preparation method of phenalkamine is as follows: Phenols are added to the base amine, aldehydes are added at 50-80°C, the mixture is reacted at 75-95°C for 2.5 hours, and then vacuum dehydration is performed to obtain phenolic amine.

5. The emulsion type phenalkamine epoxy curing agent according to claim 4, characterized in that: The weight ratio of the base amine, phenols and aldehydes is (58-63.2):(47-150):

15.

6. The emulsion type phenalkamine epoxy curing agent according to claim 4, characterized in that: The weight ratio of the added amount of the terminal hydroxyl polyether to the aldehydes is 156:

15.

7. The emulsion type phenalkamine epoxy curing agent according to claim 6, characterized in that: The number average molecular weight of the epoxy-terminated polyether is ≤1000.

8. The emulsion type phenalkamine epoxy curing agent according to claim 4, characterized in that: The base amine is one or more of ethylenediamine, 1,3-propylenediamine, 1,4-butylenediamine, 1,5-pentanediamine, 2-methylpentanediamine, 1,6-hexanediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine, polyethyleneimine, 1,6-cyclohexanediamine, diethyltoluenediamine, isophoronediamine, p-xylylenediamine, and m-xylylenediamine; The phenols are one or two of phenol, cardanol, tert-butylphenol and nonylphenol; The aldehyde is formaldehyde or paraformaldehyde.

9. The emulsion type phenalkamine epoxy curing agent according to claim 1, characterized in that: The weight ratio of the prepolymer A to the prepolymer B is (15-20): (132-187.1).

10. An emulsion type phenolic amine epoxy curing agent, characterized in that: The curing agent is prepared by the preparation method according to any one of claims 1 to 9, wherein the solid content of the curing agent is 40-60%, and the theoretical active hydrogen equivalent is 310-333 g / Eq.

Images