A modified amine resin and its preparation method and application

Abstract

The application provides a modified amine resin and a preparation method and application thereof. The structure of the modified amine resin is as follows: four secondary amine groups in the modified amine resin are directly connected to an alicyclic group, the alicyclic group can reduce the electron cloud density on the N atom in the amine group, so that the lone pair electrons are not easily attacked by H+, thus having good acid resistance; and since the modified amine resin has four amine groups which are far apart and are all secondary amines, after crosslinking with an epoxy resin, a coating layer with good crosslinking density and toughness can be formed. The strong acid-resistant coating based on the modified amine resin and the epoxy resin has good acid resistance, has excellent resistance to hydrochloric acid, nitric acid and sulfuric acid, can resist 10% concentration of hydrochloric acid at 60 DEG C for a long time without film damage, blistering or peeling, and thus plays a good protective role on the steel substrate in such an environment.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of acid-resistant coatings, and particularly relates to a modified amine resin as well as a preparation method and application thereof. BACKGROUND

[0002] In the chemical industry, the storage problem of acid solution has been difficult to solve. Since the metal substrate is prone to chemical corrosion under acidic conditions, it may cause safety hazards such as leakage, failure, and even production accidents. Therefore, inorganic acid storage is usually carried out in a storage tank made of polypropylene at home and abroad. However, this method is expensive, and due to the processing technology, the internal storage space is usually small, which is difficult to meet the needs of industrialized mass production. Therefore, the chemical industry urgently needs a strong acid-resistant coating composition to provide corrosion protection for the inner wall of the storage tank, such as a steel storage tank, to reduce the storage and use cost of acid solution and improve production efficiency. In recent years, domestic and foreign coating enterprises have successively launched many acid-resistant coatings mainly based on phenolic epoxy. This coating usually has good resistance to sulfuric acid (concentration less than 20%), but the resistance to hydrochloric acid and nitric acid is generally poor. The industry urgently needs an acid-resistant coating with wider applicability and better performance to fill the gap in the chemical industry. SUMMARY

[0003] To solve all or part of the above technical problems, the application provides the following technical solutions:

[0004] One of the purposes of the application is to provide a modified amine resin, which has the following structure:

[0005]

[0006] The amine group in the modified amine resin is directly connected to the alicyclic ring, and the alicyclic ring structure can reduce the electron cloud density on the N atom, and its lone pair electrons are not easy to be attacked by H + , so that the modified amine resin exhibits good acid resistance.

[0007] The second purpose of the application is to provide a preparation method of the modified amine resin, which comprises the following steps:

[0008] The first addition reaction is carried out on a first mixed reaction system containing methylcyclohexane diamine and 1,6 hexanediol diglycidyl ether to obtain an HH modified resin;

[0009] The second addition reaction is carried out on a second mixed reaction system containing the HH modified resin and allyl glycidyl ether to obtain a modified amine resin.

[0010] The structure of the HH modified resin is shown in the following formula:

[0011]

[0012] In some embodiments, the mass ratio of methylcyclohexane diamine (HTDA) to 1,6 hexanediol diglycidyl ether (HDK) in the first mixed reaction system is 1.15-1.25:1. During the first addition reaction, the HTDA is kept in excess, and the HK is gradually added dropwise into the HTDA, which can ensure that the primary amine is consumed preferentially during the reaction, and the generated HH modified resin does not form a chain structure, so it is appropriate to set the mass ratio of HTDA and HK to 1.15-1.25:1.

[0013] In some embodiments, the mass ratio of HH modified resin to allyl glycidyl ether (AGE) in the second mixed reaction system is 2.15-2.25:1. During the second addition reaction, it is appropriate to set the mass ratio of HH modified resin to AGE to 2.15-2.25:1, because the HH modified resin is kept in excess, which can ensure that the primary amine is consumed preferentially during the reaction, and the secondary amine is preserved, thereby improving the structural stability and regularity of the modified amine resin reaction product.

[0014] In some embodiments, the weight average molecular weight of the methylcyclohexane diamine is 120-140, and the active hydrogen equivalent weight is 30-35.

[0015] In some embodiments, the weight average molecular weight of the 1,6 hexanediol diglycidyl ether is 220-240, and the epoxy equivalent weight is 110-120.

[0016] In some embodiments, the weight average molecular weight of the allyl glycidyl ether is 110-130, and contains 1 epoxy group.

[0017] In some embodiments, the reaction temperature of the first addition reaction and the second addition reaction is 55-65℃.

[0018] In some embodiments, the time of the first addition reaction is 2-2.5h.

[0019] In some embodiments, the time of the second addition reaction is 1-2h.

[0020] In some embodiments, the first mixed reaction system and the second mixed reaction system further include a first solvent, and the first solvent includes xylene and butanol with a mass ratio of 6-7:3-4.

[0021] In some exemplary embodiments, the preparation method comprises: adding a mixed solvent of xylene and butanol in a mass ratio of 6-7:3-4 into a reaction kettle, adding methylcyclohexane diamine under low-speed stirring, and heating to 55-65℃, then adding 1,6-hexanediol diglycidyl ether in batches until the mass ratio of methylcyclohexane diamine and 1,6-hexanediol diglycidyl ether reaches 1.15-1.25:1, and performing addition reaction under low-speed stirring at 55-65℃ for 2-2.5h to obtain a HH modified resin solution, then adding allyl glycidyl ether in batches under stirring until the mass ratio of HH modified resin and allyl glycidyl ether reaches 2.15-2.25:1, and then performing reaction under stirring at 55-65℃ for 1-2h to obtain a modified amine resin after cooling to room temperature.

[0022] Exemplarily, a mixed solvent of toluene and butanol is added into a reaction kettle, a stirrer is started to stir at a speed of 300-500r / min, then methylcyclohexane diamine is added and the temperature is controlled to 55-65℃, then 1,6-hexanediol diglycidyl ether is slowly added into the methylcyclohexane diamine solution in a mass ratio of 1.15-1.25:1 of methylcyclohexane diamine and 1,6-hexanediol diglycidyl ether under stirring, and a pre-addition reaction is performed for 2-2.5h under continuous stirring and temperature control at 55-65℃ to obtain a HH modified resin solution; then allyl glycidyl ether is slowly added into the HH modified resin in a mass ratio of 2.15-2.25:1 of HH modified resin and allyl glycidyl ether under stirring, and then a reaction is performed under stirring at 55-65℃ for 1-1.5h to obtain a modified amine resin.

[0023] The third object of the present application is to provide a modified amine resin prepared according to any of the above-mentioned methods.

[0024] The fourth object of the present application is to provide the use of the modified amine resin in preparing acid-resistant coatings.

[0025] The fifth object of the present application is to provide a strong acid-resistant coating, which comprises: a first component and a second component, the first component comprises, in parts by mass, 35-45 parts of epoxy resin, 40-50 parts of pigment and filler, and 10-15 parts of second solvent; the second component comprises 54-58 parts of the modified amine resin and 15-20 parts of second solvent; and the mass ratio of the first component and the second component is 5.6-7.0:1.

[0026] The beneficial effect of using the modified amine resin to form the coating is that methylcyclohexanediamine is an alicyclic structure containing four primary amines. If the structure is not modified and directly reacts with the first component, on the one hand, the reaction is too violent, which is not conducive to construction, and the structure of the product is irregular, and the shielding performance is poor. On the other hand, the coating material formed lacks toughness and has poor mechanical properties. Therefore, in the present application, it is first pre-added with 1,6-hexanediol diglycidyl ether to form a chain structure, and the amine groups are distributed at both ends of the chain structure, and part of the primary amines are eliminated, and then the remaining primary amines are further eliminated with allyl glycidyl ether, so that the finally generated modified amine resin structure has four secondary amine groups, and there is a certain interval between them.

[0027] In the structure of the modified amine resin, the four secondary amine groups are directly connected to the alicyclic ring. The alicyclic structure can reduce the electron cloud density on the N atom of the amine group, so that the lone pair electrons are not easily attacked by H+. Therefore, it has good acid resistance. On this basis, since there are four amine groups in the structure which are far apart and are all secondary amines, after crosslinking with the epoxy resin of the first component, the crosslinking density and toughness of the coating film can be ensured, and the glass transition temperature rising curve during the reaction is more gentle, and the final reaction rate is higher. Therefore, the chemical structure of the coating material is more regular, and has more excellent mechanical properties and shielding performance.

[0028] In addition, the present application determines through systematic research that the mass ratio of the first component to the second component is more suitable for 5.6-7.0:1. If the mass ratio of the first component is too high, the epoxy component is too much, and after forming the paint film, there are still many epoxy groups that do not participate in the reaction, so the crosslinking density is low, which affects the acid resistance of the coating. If the mass ratio of the first component is too low, the amine component is too much, which will adversely affect the crosslinking density, and on the other hand, due to the hydrophilicity of amine, the remaining amine will make the paint film easy to absorb water, thereby affecting the acid resistance of the paint film.

[0029] The preparation method of the modified amine resin provided by the present application can obtain a solution containing the modified amine resin. When the second component is prepared, the solution containing the modified amine resin can be directly mixed with the second solvent to form the second component. Of course, the solution containing the modified amine resin obtained by preparation can also be subjected to post-treatment such as solvent removal, and the modified amine resin obtained is mixed with the second solvent to ensure that the second component includes 54-58 parts by mass of the modified amine resin and 15-20 parts by mass of the second solvent.

[0030] In some embodiments, the epoxy resin has an epoxy equivalent weight of 450 or more. For example, the epoxy equivalent weight is 450-560. The weight average molecular weight of the epoxy resin is, for example, 900-1120.

[0031] In some embodiments, the color filler includes a combination of one or more of titanium dioxide, black iron oxide, red iron oxide, talc powder, and silicon powder, but is not limited thereto.

[0032] In some embodiments, the strong acid-resistant coating composition further includes 1-2 parts of an auxiliary agent.

[0033] In some embodiments, the auxiliary agent includes a combination of one or more of a dispersing agent, a defoaming agent, a leveling agent, and a rheological auxiliary agent, but is not limited thereto.

[0034] In some embodiments, the second solvent includes a combination of one or more of xylene, propylene glycol methyl ether (PM), methyl isobutyl ketone (MIBK), acetone, n-butanol, and acetylacetone, but is not limited thereto.

[0035] In some embodiments, the method for preparing the strong acid-resistant coating composition includes: uniformly mixing an epoxy resin, a color filler, an optional auxiliary agent, and a second solvent to obtain a first component; uniformly mixing the modified amine resin and the second solvent to obtain a second component; and uniformly mixing the first component and the second component according to the mass ratio to obtain the strong acid-resistant coating.

[0036] In some embodiments, the method for preparing the first component includes: uniformly mixing the epoxy resin with the color filler, the optional auxiliary agent, and a portion of the second solvent in sequence, and then dispersing at a speed of 2000-3000 r / min for 25-30 min, and then adjusting the viscosity of the obtained mixture to 120-130 KU with another portion of the second solvent to obtain the first component.

[0037] In some embodiments, the method for preparing the second component includes: uniformly mixing the modified amine resin and the second solvent under low-speed stirring at a speed of 300-500 r / min to obtain the second component. The second component is an amine component and is used for cross-linking with the epoxy in the first component.

[0038] In some embodiments of the present application, the low-speed stirring refers to a speed of 500 r / min or less, the medium-speed stirring refers to a speed of 500-2000 r / min, and the high-speed stirring refers to a speed of 2000 r / min or more; and the high-speed dispersion refers to a speed of 2000-3000 r / min.

[0039] The sixth object of the present application is a strong acid-resistant coating layer, which is a cured product of the strong acid-resistant coating according to any one of the technical solutions.

[0040] The strong acid-resistant coating and the coating layer can be applied to the steel coating protection in an acid environment. The strong acid-resistant coating can resist 10wt% hydrochloric acid, 25wt% sulfuric acid and 10wt% nitric acid for 90 days at room temperature without film bubbling, peeling or softening; and can resist 10wt% hydrochloric acid for 60 days at 60℃ without film bubbling, peeling or softening.

[0041] The seventh object of the present application is to provide an acid-resistant structure, comprising a substrate and the strong acid-resistant coating formed on the surface of the substrate.

[0042] In some embodiments, the substrate is steel.

[0043] The acid-resistant structure can be used to prepare a tank for containing acid, effectively solving the problem that the existing acid storage tank such as a steel storage tank is easy to be corroded.

[0044] Compared with the prior art, the present application has the following beneficial effects:

[0045] (1) The amine group in the modified amine resin is directly connected to the alicyclic ring, and the alicyclic ring structure can reduce the electron cloud density on the N atom, and the lone pair electrons are not easy to be attacked by H + , showing good acid resistance;

[0046] (2) The strong acid-resistant coating composition and the coating material have good acid resistance, especially excellent resistance to hydrochloric acid, nitric acid and sulfuric acid, and can resist 10% concentration of hydrochloric acid corrosion at 60℃ without film damage, bubbling or peeling, thereby protecting the steel substrate in such an environment;

[0047] (3) The strong acid-resistant coating material coated on the surface of the steel structure can effectively prevent the structure from being damaged and the strength from being reduced due to corrosion of the acid solution on the surface of the steel structure in an acid solution environment, thereby prolonging the corrosion protection period of the steel structure in the acid solution environment, and the coating material is easy to prepare and suitable for large-scale production and application. DETAILED DESCRIPTION

[0048] The technical solutions of the present application will be described in detail below with specific embodiments, so that those skilled in the art can better understand and implement the technical solutions of the present application. The specific functional details disclosed herein should not be interpreted as limiting, but only as the basis of the claims and for teaching those skilled in the art to adopt the representative basis of the present application in different ways in any appropriate detailed embodiment.

[0049] The reagents and raw materials used in the following examples are all commercially available, and the test methods that do not specify specific conditions are generally performed under conventional conditions or according to the conditions recommended by the respective manufacturers.

[0050] Example 1

[0051] This embodiment provides a modified amine resin and its preparation method, specifically including the following steps:

[0052] A mixed solvent of xylene and butanol (mass ratio of xylene to n-butanol 7:3) was added to a reaction vessel. 1150g of methylcyclohexanediamine was added under low-speed stirring at 400r / min, and the temperature was raised to 55℃. Then, 1000g of 1,6-hexanediol diglycidyl ether was added in batches, and the addition reaction was carried out at 55℃ for 2.5h under stirring at 400r / min to obtain a solution containing HH-modified resin. Subsequently, while maintaining stirring, 1000g of allyl glycidyl ether was added in batches, and the reaction was carried out at 55℃ for 2h under stirring. After cooling to room temperature, a modified amine resin solution containing modified amine resin was obtained.

[0053] The results of the intermediate HH-modified resin obtained in the above preparation process are as follows:

[0054]

[0055] The structure of the obtained modified amine resin is as follows:

[0056]

[0057] This embodiment also provides a high-performance acid-resistant coating composition containing the modified amine resin solution prepared above:

[0058] 4000g of epoxy resin E-20 (NPCN-601, epoxy equivalent 450-560g / mol) was sequentially mixed with 2300g of titanium dioxide, 2200g of silica powder, 50g of dispersant (BYK-110), 50g of defoamer (BYK-066N), 100g of rheology modifier (monoral-9000), and 1000g of a mixed solvent of xylene and n-butanol (xylene to n-butanol mass ratio 7:3). The mixture was dispersed at high speed at 2500r / min for about 30min. Then, the viscosity of the mixture was adjusted to about 120KU with 300g of a mixed solvent of xylene and butanol (xylene to n-butanol mass ratio 7:3) to obtain the first component.

[0059] Add 1600g of the above modified amine resin solution (where the mass concentration of modified amine resin is about 68%) and 400g of xylene to the reactor, and stir and disperse at a medium speed of 1000r / min for 10 minutes to obtain the second component;

[0060] The first component and the second component are mixed in a mass ratio of about 5.6:1 to obtain a strong acid-resistant coating composition.

[0061] Example 2

[0062] The present example provides a modified amine resin and a preparation method thereof, which specifically comprises the following steps:

[0063] In a reaction kettle, 1500 g of a mixed solvent of xylene and butanol (mass ratio of xylene to n-butanol is 6:4) is added, and 1250 g of methylcyclohexanediamine is added under low-speed stirring at 400 r / min, and the temperature is raised to 60°C. Then 1000 g of 1,6-hexanediol diglycidyl ether is added in batches, and the addition reaction is carried out at 60°C under stirring at 400 r / min for 2 h to obtain a solution containing a HH-modified resin. Then, while keeping the stirring state, 1000 g of allyl glycidyl ether is added in batches, and then the reaction is carried out at 60°C under stirring for 1 h to obtain a modified amine resin solution containing a modified amine resin after cooling to room temperature.

[0064] The present example also provides a strong acid-resistant coating composition containing the modified amine resin solution prepared above:

[0065] 4000 g of epoxy resin E-20 (NPCN-601, epoxy equivalent weight 450-560 g / mol) is sequentially mixed with 2000 g of titanium white, 300 g of iron oxide black, 2200 g of silica powder, 50 g of dispersant (BYK-110), 50 g of defoaming agent (BYK-066N), 100 g of rheological aid (monoral-9000), and 1000 g of a mixed solvent of xylene and n-butanol (mass ratio of xylene to n-butanol is 6:4) to obtain a first component, and the mixture is uniformly dispersed at a high speed of 2500 r / min for about 30 min. Then, the viscosity of the mixture is adjusted to about 120 KU with 300 g of a mixed solvent of xylene and butanol (mass ratio of xylene to n-butanol is 6:4) to obtain a first component.

[0066] In a reaction kettle, 1700 g of the modified amine resin solution (wherein the mass concentration of the modified amine resin is about 68.4%) and 300 g of xylene are added, and the mixture is dispersed at a medium speed of 1000 r / min for 10 min to obtain a second component.

[0067] The first component and the second component are mixed in a mass ratio of about 5.6:1 to obtain a strong acid-resistant coating composition.

[0068] Example 3

[0069] The present example provides a modified amine resin and a preparation method thereof, which specifically comprises the following steps:

[0070] In a reaction kettle, 1500 g of mixed solvent of xylene and butanol (mass ratio of xylene to n-butanol is 7:3) was added, 1200 g of methylcyclohexanediamine was added under the condition of low-speed stirring at 400 r / min, and the temperature was raised to 65°C, then 1000 g of 1,6-hexanediol diglycidyl ether was added in batches, and the addition reaction was carried out at 65°C under the condition of stirring at 400 r / min for 2 h to obtain a solution containing a modified amine resin; then, while keeping stirring, 1000 g of allyl glycidyl ether was added in batches, and then the reaction was carried out at 65°C under the condition of stirring for 1 h, and the modified amine resin solution containing the modified amine resin was prepared by cooling to room temperature.

[0071] The present embodiment also provides a strong acid-resistant coating composition containing the modified amine resin solution prepared above:

[0072] 4000 g of epoxy resin E-20 (NPCN-601, epoxy equivalent weight 450-560 g / mol) was sequentially mixed with 2000 g of titanium white, 300 g of red iron oxide, 2200 g of silica powder, 50 g of dispersant (BYK-110), 50 g of defoaming agent (BYK-066N), 100 g of rheological aid (monoral-9000), 1000 g of mixed solvent of xylene and n-butanol (mass ratio of xylene to n-butanol is 7:3), and uniformly mixed, and dispersed at a high speed of 2500 r / min for about 30 min, then the viscosity of the mixture was adjusted to about 120 KU with 300 g of mixed solvent of xylene and butanol (mass ratio of xylene to n-butanol is 7:3), to obtain a first component;

[0073] 1650 g of modified amine resin solution (mass concentration of modified amine resin is 67.7%) and 350 g of xylene were added to a reaction kettle, and dispersed at a medium speed of 1000 r / min for 10 min to obtain a second component;

[0074] The first component and the second component were mixed uniformly according to a mass ratio of about 6.0:1 to obtain a strong acid-resistant coating composition.

[0075] Example 4

[0076] The present embodiment provides a modified amine resin and a preparation method thereof, which specifically comprises the following steps:

[0077] In a reaction kettle, 1500 g of mixed solvent of xylene and butanol (mass ratio of xylene to n-butanol is 7:3) was added, 1150 g of methylcyclohexanediamine was added under the condition of low speed stirring at 400 r / min, and the temperature was raised to 55°C, then 1000 g of 1,6-hexanediol diglycidyl ether was added in batches, and the addition reaction was carried out at 55°C under the condition of stirring at 400 r / min for 2.5 h to obtain a solution containing HH modified resin, then the stirring state was maintained, 1000 g of allyl glycidyl ether was added in batches, and then the reaction was carried out at 55°C under the condition of stirring for 2 h, and the modified amine resin solution containing modified amine resin was prepared by cooling to room temperature.

[0078] The present embodiment also provides a strong acid-resistant coating composition containing the modified amine resin solution prepared above:

[0079] 4000 g of epoxy resin E-20 (NPCN-601, epoxy equivalent weight 450-560 g / mol) was sequentially mixed with 3000 g of silicon powder, 500 g of red iron oxide, 1000 g of talc powder, 50 g of dispersant (BYK-110), 50 g of defoaming agent (BYK-066N), 100 g of rheological aid (monoral-9000), 1000 g of mixed solvent of xylene and n-butanol (mass ratio of xylene to n-butanol is 7:3) to obtain a first component;

[0080] 1600 g of modified amine resin solution (mass concentration of modified amine resin is about 68%) and 400 g of xylene were added to a reaction kettle, and the mixture was dispersed at 1000 r / min for 10 minutes to obtain a second component;

[0081] The first component and the second component were mixed uniformly according to a mass ratio of about 5.6:1 to obtain a coating composition for forming a strong acid-resistant coating material.

[0082] Example 5

[0083] The method for preparing the modified amine resin in Example 5 is the same as that in Example 1.

[0084] 3500g of epoxy resin E-20 (NPCN-601, epoxy equivalent 450-560g / mol) was sequentially mixed with 3000g of silica powder, 500g of iron oxide red, 500g of talc, 25g of dispersant (BYK-110), 25g of defoamer (BYK-066N), 50g of rheology modifier (monoral-9000), and 800g of a mixed solvent of xylene and n-butanol (xylene to n-butanol mass ratio 7:3). The mixture was dispersed at high speed at 2500r / min for about 30min. Then, the viscosity of the mixture was adjusted to about 120KU with 200g of a mixed solvent of xylene and butanol (xylene to n-butanol mass ratio 7:3) to obtain the first component.

[0085] 1600g of modified amine resin solution (with a mass concentration of approximately 68%) and 400g of xylene were added to a reaction vessel and stirred at a medium speed of 1000r / min for 10 minutes to obtain the second component.

[0086] The first component and the second component are mixed evenly at a mass ratio of approximately 6.4:1 to obtain a coating composition for forming a strong acid-resistant coating material.

[0087] Example 6

[0088] The method for preparing the modified amine resin in Example 6 is the same as that in Example 1.

[0089] 4500g of epoxy resin E-20 (NPCN-601, epoxy equivalent 450-560g / mol) was sequentially mixed with 4000g of silica powder, 500g of iron oxide red, 500g of talc, 50g of dispersant (BYK-110), 50g of defoamer (BYK-066N), 50g of rheology modifier (monoral-9000), and 1200g of a mixed solvent of xylene and n-butanol (xylene to n-butanol mass ratio 7:3). The mixture was dispersed at high speed at 2500r / min for about 30min. Then, the viscosity of the mixture was adjusted to about 120KU with 300g of a mixed solvent of xylene and butanol (xylene to n-butanol mass ratio 7:3) to obtain the first component.

[0090] 1600g of modified amine resin solution (with a mass concentration of approximately 68%) and 400g of xylene were added to a reaction vessel and stirred at a medium speed of 1000r / min for 10 minutes to obtain the second component.

[0091] The first component and the second component are mixed evenly at a mass ratio of approximately 6.8:1 to obtain a coating composition for forming a strong acid-resistant coating material.

[0092] Comparative Example 1

[0093] Comparative Example 1 is substantially the same as Example 1, except that in preparing the resin, the methylcyclohexane diamine in Example 1 is replaced with isophorone diamine, and the prepared resin is used to prepare a strong acid-resistant coating composition.

[0094] Since one of the two amine groups of isophorone diamine is not directly connected to the six-membered ester ring, although it is also an alicyclic amine, the N atom is connected to a methyl group, so the lone pair of electrons on the N atom cannot be effectively dispersed, and thus the acid resistance is reduced.

[0095] Comparative Example 2

[0096] Comparative Example 2 is substantially the same as Example 1, except that in preparing the modified resin, the addition step of allyl glycidyl ether is cancelled, i.e., the intermediate product HH modified resin is directly used to replace the modified amine resin to prepare the second component.

[0097] The HH modified resin contains 2 secondary amines and 4 primary amines, and since the reaction speed of the primary amine is much faster than that of the secondary amine, the primary amine will preferentially react with the epoxy group. The rapid reaction of the primary amine will cause the glass transition temperature of the coating film to rise too quickly, thereby reducing the movement speed of the molecules, and thus reducing the collision probability of the epoxy group and the amine group, resulting in a reduction in the final reaction rate, which will reduce the crosslinking density of the paint film, thereby reducing the shielding performance of the acidic liquid.

[0098] Comparative Example 3

[0099] Comparative Example 3 is substantially the same as Example 1, except that the mass ratio of the first component to the second component in Comparative Example 3 is 8:1.

[0100] Comparative Example 4

[0101] Comparative Example 4 is substantially the same as Example 1, except that the mass ratio of the first component to the second component in Comparative Example 3 is 5.3:1.

[0102] The present application finds that when the mass ratio of the first component to the second component is too low, there will be more amine groups remaining in the paint film, and due to the water absorption characteristics of the amine, the paint film will be prone to softening and peeling in a medium immersion environment, especially under acidic conditions, which will react with the acid, causing the adhesion performance of the paint film to fail.

[0103] Comparative Example 5

[0104] Comparative Example 5 is substantially the same as Example 1, except that in the first component of Comparative Example 5, the filler is titanium dioxide 2300 g and silicon powder 3500 g.

[0105] When the pigment volume concentration is too high, the resin in the coating film is not sufficient to form a good package for the pigment filler, which will cause the coating film to be loose, the shielding performance to be reduced, and thus the acid resistance to be reduced.

[0106] Comparative Example 6

[0107] Comparative Example 6 is substantially identical to Example 1, except that the reaction temperature in the synthesis of the modified amine resin in Comparative Example 6 is 45°C.

[0108] A lower reaction temperature can result in an incomplete addition reaction, which can make it difficult to ensure that the product formed during the synthesis has the desired structure, which can in turn affect the performance of the coating.

[0109] Comparative Example 7

[0110] Comparative Example 7 differs from Example 1 only in that the epoxy resin E-20 in Example 1 is replaced with epoxy resin E-51 (the epoxy equivalent weight of epoxy resin E-51 is 190-210).

[0111] The use of an epoxy resin with a lower epoxy equivalent weight can result in an excess of epoxy groups, and on the other hand, the small molecule epoxy resin has poor toughness and a low content of hydroxyl groups in its structure, and the distribution of the hydroxyl groups is irregular, so it has a large effect on adhesion. When the adhesion of the paint film is reduced, the resistance to penetration of the medium is also reduced.

[0112] Comparative Example 8

[0113] Comparative Example 8 uses a commercially available conventional acid-resistant coating (a phenolic epoxy coating) as a control.

[0114] Comparative Example 9

[0115] The second component of the coating composition provided in Comparative Example 9 is a simple mixture of methylcyclohexane diamine, 1,6-hexanediol diglycidyl ether, allyl glycidyl ether, and a solvent, and the mass ratio of methylcyclohexane diamine, 1,6-hexanediol diglycidyl ether, allyl glycidyl ether, and the solvent is 1.15:1:1. The first component is the same as in Example 1, and the mass ratio of the first component to the second component is the same as in Example 1.

[0116] When these three materials are simply mixed without modification, they cannot form an effective HHA modified resin structure. The methylcyclohexane diamine and the two glycidyl ethers will react in a disordered and slow manner, and will eventually form some amine structure, and the distribution of the molecular weight will be very random. Therefore, when the second component reacts with the first component, the structure of the paint film will also have a lot of randomness. That is, the crosslinking density in some areas will be very high, and the crosslinking density in some areas will be very low. In areas with a high crosslinking density, the paint film is prone to peeling due to shrinkage stress during the curing process, and in areas with a low crosslinking density, the medium is more easily penetrated, and the shielding performance is very low.

[0117] The coating compositions of Examples 1-6 and Comparative Examples 1-9 and a commercially available conventional acid-resistant coating were respectively applied on the surface of a sandblasted steel plate to form acid-resistant coatings, and the properties of the coatings were respectively tested, and the corresponding test results are shown in Table 1. The test method of the impact resistance in Table 1 is according to GB / T 20624.1, and the medium resistance test method is according to GB / T 9274. The test results in Table 1 are the average values of the test results of multiple batches of products.

[0118] Table 1 Test results of the properties of the coatings formed by the coating compositions of the examples and the comparative examples of the present application

[0119]

[0120]

[0121] As can be seen from Table 1, the coating compositions of Examples 1-4 can be used to form a strong acid-resistant coating material, which can resist 10% hydrochloric acid, 25% sulfuric acid and 10% nitric acid for 90 days at room temperature, and the paint film does not appear to be blistering, peeling or softening. At 60°C, it can resist 10% hydrochloric acid for 60 days, and the paint film does not appear to be blistering, peeling or softening. The comprehensive performance is far superior to that of the commercially available conventional acid-resistant epoxy coating.

[0122] In addition, the present inventors also carried out tests according to the manners of Examples 1-4 using other raw materials and conditions listed in the present specification, and similar results were obtained.

[0123] Aspects, embodiments, features and examples of the present application should be considered illustrative in all aspects and are not intended to limit the present application, and the scope of the present application is only defined by the claims. Other embodiments, modifications and uses will be apparent to those skilled in the art without departing from the spirit and scope of the claimed application.

[0124] In addition, the present inventors also carried out tests according to the manners of Examples 1-4 using other raw materials and conditions listed in the present specification, and similar results were obtained.

[0125] While the application has been described with reference to the illustrative embodiments, those skilled in the art will understand that various other changes, omissions, and / or additions can be made without departing from the spirit and scope of the application. Further, many modifications can be made to adapt a particular situation or material to the teachings of the application without departing from its scope. Therefore, it is intended that the application not be limited to the disclosed embodiments, but will include all embodiments falling within the scope of the appended claims. Moreover, unless specifically stated otherwise, any use of the terms first, second, etc., does not denote any ordinal, or importance, but merely distinguishes one element from another.

Claims

1. A modified amine resin, the structure of which is as follows: 。 2. The method for preparing the modified amine resin according to claim 1, characterized in that, include: The first mixed reaction system containing methylcyclohexanediamine and 1,6-hexanediol diglycidyl ether was subjected to a first addition reaction at 55-65°C for 2-2.5 h to obtain HH modified resin. The second mixed reaction system containing the HH modified resin and allyl glycidyl ether is subjected to a second addition reaction at 55-65°C for 1-2 hours to obtain the modified amine resin.

3. The preparation method according to claim 2, characterized in that: In the first mixed reaction system, the mass ratio of methylcyclohexanediamine to 1,6-hexanediol diglycidyl ether is 1.15-1.25:1; and / or, in the second mixed reaction system, the mass ratio of HH-modified resin to allyl glycidyl ether is 2.15-2.25:

1.

4. The preparation method according to claim 2, characterized in that: The first mixed reaction system and the second mixed reaction system further include a first solvent, which includes xylene and butanol in a mass ratio of 6-7:3-4.

5. The application of the modified amine resin according to claim 1 in the preparation of acid-resistant coatings.

6. An acid-resistant coating, characterized in that, include: The first component and the second component, by mass parts, the first component includes 35-45 parts of epoxy resin, 40-50 parts of pigments and fillers, and 10-15 parts of the second solvent; The second component comprises 54-58 parts of the modified amine resin as described in claim 1 and 15-20 parts of the second solvent; the mass ratio of the first component to the second component is 5.6-7.0:

1.

7. The acid-resistant coating according to claim 6, characterized in that: The epoxy equivalent of the epoxy resin is 450 or higher.

8. The acid-resistant coating according to claim 6, characterized in that: The pigments and fillers include one or more of titanium dioxide, iron oxide black, iron oxide red, talc, and silica powder.

9. The acid-resistant coating according to claim 6, characterized in that: The acid-resistant coating also includes 1-2 parts of additives, which include one or more combinations of dispersants, defoamers, leveling agents and rheology modifiers.

10. The acid-resistant coating according to claim 6, characterized in that: The second solvent includes one or more combinations of xylene, propylene glycol methyl ether, methyl isobutyl ketone, acetone, n-butanol, and acetylacetone.

11. An acid-resistant coating, characterized in that: The acid-resistant coating comprises the cured product of the acid-resistant coating according to any one of claims 6-10.

12. An acid-resistant structure, characterized in that, include: The substrate and the acid-resistant coating of claim 11 formed on the surface of the substrate.

13. The acid-resistant structure according to claim 12, characterized in that: The substrate is steel.

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