Bismaleimide aspartic resin and preparation process thereof

Abstract

The invention provides bismaleimide aspartic resin and a preparation process thereof, and relates to the technical field of amino resin. The structure of the bismaleimide aspartic resin is # imgabs 0 #, R1 is selected from C5-C6 cycloalkyl or C6-C12 substituted cycloalkyl, and R2 is selected from a divalent organic structure which is left after primary amino is removed from a binary primary amine compound, is reactive inert with an isocyanate group at the temperature of 100 DEG C and has the average molecular weight of 50-5000. The bismaleimide aspartic resin disclosed by the invention has relatively good heat resistance, hydrolysis resistance and the like, and aspartic polyurea can be endowed with higher mechanical strength.

Description

Technical Field

[0001] The invention belongs to the technical field of amino resins and relates to bismaleimide aspartame resin and a preparation process thereof. Background Art

[0002] Asparagus resin is an alicyclic secondary amino resin, which is prepared by Michael addition reaction of maleic acid ester (such as diethyl maleate) and alicyclic diamine (such as 4,4'-diaminodicyclohexylmethane), and can be combined with isocyanate curing agent to obtain asparagus polyurea. The main chain structure of asparagus resin provides high weather resistance and excellent mechanical properties for asparagus polyurea, and the ester group of the side chain provides good internal plasticization and solvation for asparagus polyurea, ensuring the low viscosity and good flexibility of asparagus resin. However, due to the ester group of the side chain, the hardness, high temperature resistance and chemical resistance of asparagus polyurea are not outstanding, which limits the application of asparagus polyurea under harsh conditions. In addition, the stability of the ester group is poor, and it is not stable enough under water environment, high temperature and other conditions, resulting in weight loss, loss of gloss and shrinkage of asparagus polyurea under water environment, high temperature and other conditions.

[0003] Therefore, it is necessary to modify the asparagus resin to improve its water resistance, high temperature resistance and other properties, and then improve the hardness, high temperature resistance, chemical resistance, water resistance and other properties of the asparagus polyurea.

[0004] The imide structure has good stability, water resistance and temperature resistance. The prior art reports the use of maleimide to replace maleate to prepare alicyclic secondary amine resins, but due to the limitation of the maleimide structure, the structural design of alicyclic secondary amine resins is limited, the flexibility is insufficient, and it is not easy to obtain alicyclic secondary amine resins with various structures. Summary of the invention

[0005] The ester group in the asparagine resin can react with the double-terminal primary amino compound under the action of a catalyst to generate an imide asparagine resin. Moreover, the double-terminal primary amino compound has many varieties, a wide range of sources, and low cost, so the imide asparagine resin can be given a more flexible structural design, a lot of performance and a wider range of applications. Based on this, the present invention provides bismaleimide asparagine resin and its preparation process.

[0006] The technical solution of the present invention is as follows:

[0007] Bismaleimide aspartame resin has the structure shown in the following formula (1):

[0008]

[0009] Wherein, R1 is selected from C5-C6 cycloalkyl or C6-C12 substituted cycloalkyl, and R2 is selected from the divalent organic structure with an average molecular weight of 50-5000 which is inert to the isocyanate group at 100°C and remains after the primary amino group is removed from the divalent primary amine compound.

[0010] Preferably, R1 is selected from cyclopentyl, C6-C10 substituted cyclopentyl, cyclohexyl or C7-C12 substituted cyclohexyl.

[0011] Preferably, the dibasic primary amine compound is selected from C2-C18 alkyl diamine, cyclopentane diamine, cyclohexane diamine or C6-C20 substituted cycloalkyl diamine.

[0012] Preferably, the diprimary amine compound is selected from C6-C12 alkyl diamines.

[0013] The preparation process of the bismaleimide asparagine resin described in any of the above embodiments is obtained by reacting the mono-secondary amine asparagine resin represented by the following formula (2) with the dibasic primary amine compound to form an imide reaction.

[0014]

[0015] wherein R1 has the same meaning as described above, and R3 and R4 are independently selected from C1-C4 alkyl groups.

[0016] Preferably, the molar ratio of the mono-secondary amine aspartame to the di-primary amine compound is 1:0.3-0.55.

[0017] More preferably, the molar ratio of the mono-secondary amine aspartame to the di-primary amine compound is 1:0.45-0.52.

[0018] Preferably, a catalyst is added to the imide reaction, and the catalyst is selected from C8-C18 fatty acid, benzotriazole or substituted benzotriazole.

[0019] More preferably, the weight of the catalyst is 0.1-0.5% of the weight of the mono-secondary amino aspartic resin.

[0020] Preferably, said R3 and said R4 are independently selected from methyl or ethyl.

[0021] The beneficial effects of the present invention are:

[0022] (1) The R2 structure connected in the middle of the bismaleimide asparagine resin of the present invention and the R1 structure at both ends can be flexible and varied, giving the bismaleimide asparagine resin more structural designs and different properties.

[0023] (2) The preparation process of the bismaleimide asparagine resin of the present invention is relatively simple and can be obtained through two steps. The first step is to react a monoamine compound with a maleate to obtain a mono-secondary amine asparagine resin, and then the mono-secondary amine asparagine resin is reacted with a diprimary amine compound to obtain an imide resin. DETAILED DESCRIPTION

[0024] The technical solution of the present invention is further illustrated and described below through specific implementation methods.

[0025] In order to improve the heat resistance, hydrolysis resistance, mechanical strength and other properties of asparagine resin, the present invention proposes a bismaleimide asparagine resin having a structure as shown in the following formula (1):

[0026]

[0027] Wherein, R1 is selected from C5-C6 cycloalkyl or C6-C12 substituted cycloalkyl, and R2 is selected from the divalent organic structure with an average molecular weight of 50-5000 which is inert to the isocyanate group at 100°C and remains after the primary amino group is removed from the divalent primary amine compound.

[0028] The bismaleimide aspart resin of the present invention can obtain bismaleimide aspart resins with different structures and properties by adjusting the structures of R1 and R2, such as adjusting the operation time, surface drying time, and actual drying time after the bismaleimide aspart resin is mixed with the isocyanate curing agent. The mechanical strength and heat resistance of the polyurea material after the bismaleimide aspart resin and the isocyanate curing agent are further improved by introducing R2 with a rigid structure.

[0029] In a preferred embodiment of the present invention, R1 is selected from cyclopentyl, C6-C10 substituted cyclopentyl, cyclohexyl or C7-C12 substituted cyclohexyl. Using the above technical solution, R1 can provide steric hindrance for adjacent secondary amine groups, reduce the reactivity of secondary amine groups, and avoid the bismaleimide asparagine resin and curing agent from reacting too fast. For example, R1 can be cyclopentyl, cyclohexyl, 2-methylcyclohexyl, 3-methylcyclohexyl, 4-methylcyclohexyl, 2-ethylcyclohexyl, etc. Moreover, different R1 has different steric hindrance for adjacent secondary amine groups, such as 2-ethylcyclohexyl>2-methylcyclohexyl>cyclohexyl.

[0030] In a preferred embodiment of the present invention, the dibasic primary amine compound is selected from C2-C18 alkyl diamine, cyclopentane diamine, cyclohexane diamine or C6-C20 substituted cycloalkyl diamine. By adopting the above technical scheme, the diprimary amine compound is selected from C2-C18 alkyl diamines, such as 2-methyl-1,5-pentanediamine, 1,6-hexanediamine, 1,8-octanediamine, 1,12-dodecyldiamine, 1,18-octadecyldiamine, etc., which have good flexibility and the obtained polyurea material has high flexibility; the diprimary amine compound is selected from cyclohexanediamine or C6-C20 substituted cycloalkyl diamines, such as 1,3-cyclohexanediamine, 1,4-cyclohexanediamine, 4,4'-diaminodicyclohexylmethane, 4-methyl-1,3-cyclohexanediamine, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, etc., which can not only improve the rigidity of the bismaleimide aspartame resin structure and improve the mechanical strength of the polyurea material, but also improve the heat resistance of the polyurea material and further reduce the reactivity of the adjacent secondary amine groups.

[0031] In a preferred embodiment of the present invention, the diprimary amine compound is selected from C6-C12 alkyl diamine. With the above technical solution, the steric hindrance of the reaction between the primary amino group and the ester group during the imide reaction is low, which is more conducive to increasing the reaction rate and promoting the reaction to completion. For example, the diprimary amine compound can be 1,6-hexanediamine, 1,8-octanediamine, 1,12-dodecyldiamine, 1,18-octadecyldiamine, etc.

[0032] On the other hand, the present invention provides a process for preparing the bismaleimide asparagine resin described in any of the above embodiments, which is obtained by reacting the mono-secondary amine asparagine resin represented by the following formula (2) with a diprimary amine compound to form an imide:

[0033]

[0034] wherein R1 has the same meaning as described above, and R3 and R4 are independently selected from C1-C4 alkyl groups.

[0035] In order to obtain the bismaleimide asparagine resin of the present invention, two mono-secondary amino asparagine resin molecules are required to react with one di-primary amine compound molecule. In a preferred embodiment of the present invention, the molar ratio of the mono-secondary amino asparagine resin to the di-primary amine compound is 1:0.3-0.55. When the mono-secondary amino asparagine resin is excessive relative to the di-primary amine compound, or the mono-secondary amino asparagine resin is insufficient relative to the di-primary amine compound, there is still unreacted mono-secondary amino asparagine resin or di-primary amine compound in the product, and the product can be purified by separation, such as separation and purification by separation column method. For example, the molar ratio of the mono-secondary amine aspartame resin to the di-primary amine compound can be any value among 1:0.3, 1:0.33, 1:0.35, 1:0.37, 1:0.38, 1:0.4, 1:0.42, 1:0.43, 1:0.45, 1:0.47, 1:0.48, 1:0.49, 1:0.5, 1:0.51, 1:0.52, 1:0.53, 1:0.54, 1:0.55, etc., without any particular limitation. In a more preferred embodiment, the molar ratio of the mono-secondary amino asparagine resin to the di-primary amine compound is 1:0.45-0.52, at which time the molar ratio is close to the reaction of the mono-secondary amino asparagine resin and the di-primary amine compound, and the reaction product may not need to be further processed, or may be further processed as appropriate, such as the above-mentioned separation and purification method using a separation column, which is more advantageous in industrial production, but is not a limitation of the present invention, and those skilled in the art know that even if the product purity is low, a purification method can be adopted to obtain a product with higher purity. Further preferably, the molar ratio of the mono-secondary amino asparagine resin to the di-primary amine compound is 1:0.47-0.51.

[0036] In a preferred embodiment of the present invention, a catalyst is further added to the imide reaction, and the catalyst is selected from C8-C18 fatty acids, benzotriazole or substituted benzotriazole. Adding a catalyst can make the rate of the imide reaction faster, and by directly distilling the alcohol (such as methanol, ethanol) produced or passing a gas (such as nitrogen, argon, etc.) into the reaction system to continuously take away the alcohol produced, so as to promote the imide reaction more completely. More preferably, the catalyst can be lauric acid, stearic acid, 1-hydroxybenzotriazole, etc.

[0037] In a more preferred embodiment of the present invention, the weight of the catalyst is 0.1-0.5% of the weight of the mono-secondary amino aspartic resin. For example, the weight of the catalyst can be any value of 0.1%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.5%, etc., of the weight of the mono-secondary amino aspartic resin, without particular limitation.

[0038] In a preferred embodiment of the present invention, R3 and R4 are independently selected from methyl or ethyl. In the present invention, the mono-secondary amino asparagine resin shown in formula (2) can be obtained by Michael addition reaction of maleate R3OCOCH=CHCOOR4 with monoamine compound R1NH2. When R3 and R4 are independently selected from methyl or ethyl, the maleate can be dimethyl maleate and diethyl maleate, respectively, which can be directly obtained from the market.

[0039] The technical solution of the present invention is further described and illustrated according to various embodiments below.

[0040] Preparation Example 1-3 Preparation of Mono-Secondary Amino Amine Asparagine Resin

[0041] Preparation Example 1

[0042] 1.1 mol of 2-methylcyclohexylamine was slowly added dropwise to 1 mol of diethyl maleate, and the temperature was raised to 82°C for reaction for 96 hours. After the reaction, the pressure was reduced to -0.099 MPa, and the temperature was raised to 100°C to remove low boiling substances, thereby obtaining mono-secondary amino asparagine resin.

[0043] Preparation Example 2

[0044] 1.2 mol of cyclohexylamine was slowly added dropwise to 1 mol of dimethyl maleate, and the temperature was raised to 80°C for reaction for 80 hours. After the reaction, the pressure was reduced to -0.099 MPa, and the temperature was raised to 100°C to remove low boiling substances to obtain mono-secondary amino asparagine resin.

[0045] Preparation Example 3

[0046] 1.2 mol of 3-methylcyclohexylamine was slowly added dropwise to 1 mol of diethyl maleate, and the temperature was raised to 80°C for reaction for 96 hours. After the reaction, the pressure was reduced to -0.099 MPa, and the temperature was raised to 100°C to remove low boiling substances, thereby obtaining mono-secondary amino asparagine resin.

[0047] Example 1

[0048] 1 mol of the mono-secondary amino asparagine resin of Preparation Example 1 is added to a reaction vessel, 0.3% of 1-hydroxybenzotriazole by weight of the mono-secondary amino asparagine resin is added, the temperature is raised to 90°C, 0.5 mol of 1,6-hexanediamine is added, the reaction is carried out at a constant temperature until reflux occurs, nitrogen is passed to remove the generated ethanol, the temperature is gradually raised to 135°C within 2 hours, samples are taken and FT-IR is used to detect the ester groups in the reaction system until no ester groups are detected, the pressure is reduced to -0.099 MPa, the temperature is raised to 100°C to remove low boiling points, and a brown-red viscous product is obtained, which is bismaleimide asparagine resin.

[0049] Example 2

[0050] 1 mol of the mono-secondary amino asparagine resin of Preparation Example 2 is added to a reaction vessel, and 0.25% of 1-hydroxybenzotriazole by weight of the mono-secondary amino asparagine resin is added. The temperature is raised to 90° C., and 0.47 mol of 2-methyl-1,5-pentanediamine is added. The reaction is carried out at a constant temperature until reflux occurs, and nitrogen is passed to remove the generated methanol. The temperature is gradually raised to 135° C. within 2 hours. Samples are taken and FT-IR is used to detect the ester groups in the reaction system until no ester groups are detected. The pressure is reduced to -0.099 MPa to remove low boiling points, and a brown-red viscous product is obtained, which is bismaleimide asparagine resin.

[0051] Example 3

[0052] The difference between this embodiment and embodiment 2 is that in embodiment 2, the 2-methyl-1,5-pentanediamine is adjusted from 0.47 mol to 0.5 mol, and the other steps remain unchanged.

[0053] Example 4

[0054] The difference between this embodiment and embodiment 2 is that in embodiment 2, the 2-methyl-1,5-pentanediamine is adjusted from 0.47 mol to 0.51 mol, and the other steps remain unchanged.

[0055] Example 5

[0056] 1 mol of the mono-secondary amino asparagine resin of Preparation Example 3 is added to a reaction vessel, 0.2% of 1-hydroxybenzotriazole by weight of the mono-secondary amino asparagine resin is added, the temperature is raised to 100°C, 0.5 mol of 1,8-octanediamine is added, the reaction is carried out at a constant temperature until reflux occurs, nitrogen is passed to remove the generated ethanol, the temperature is gradually raised to 135°C within 3 hours, samples are taken and FT-IR is used to detect the ester groups in the reaction system until no ester groups are detected, the pressure is reduced to -0.099 MPa, the temperature is raised to 100°C to remove low boiling points, and a brown-red viscous product is obtained, which is bismaleimide asparagine resin.

[0057] Example 6

[0058] The difference between this embodiment and embodiment 5 is that in embodiment 5, 1,8-octanediamine is replaced by an equal molar amount of 1,4-cyclohexanediamine. The other steps remain unchanged.

[0059] Example 7

[0060] The difference between this example and Example 5 is that in Example 5, 1,8-octanediamine is replaced by an equal mole of 4,4'-diaminodicyclohexylmethane. The other steps remain unchanged.

[0061] Example 8

[0062] The difference between this embodiment and embodiment 5 is that in embodiment 5, 1,8-octanediamine is replaced by an equal mole of ethylene glycol di(3-aminopropyl) ether. The other steps remain unchanged.

[0063] Comparative Example 1

[0064] F420 resin from Feiyang Junyan Co., Ltd.

[0065] Comparative Example 2

[0066] F520 resin from Feiyang Junyan Co., Ltd.

[0067] Performance test comparison

[0068] Prepare polyaspartame coating according to the following recipe.

[0069] Component A: bismaleimide aspartame or aspartame to be tested.

[0070] Component B: It is composed of an adduct curing agent prepared from 3% HDI trimer, 10% HMDI and 87% IPDI and polyether polyol.

[0071] Component A and component B were mixed evenly in a ratio of the total molar content of secondary amine groups and hydroxyl groups in component A to the molar content of isocyanate groups NCO in component B = 1:1.05 to obtain a coating composition. The coating composition was prepared into a coating film with a thickness of 0.5 mm and cured at 35±2° C. for 15 days.

[0072] The coating composition was formed into a film on a clean tinplate surface with a film thickness of 0.1 mm, and cured at 35±2°C for 15 days. The retention time after boiling in 100°C water was tested. The longer the time, the better the hydrolysis resistance.

[0073] The pot life is the time it takes for the viscosity to double at 25°C and 55% humidity.

[0074] The test performance data results are shown in Table 1.

[0075] Table 1

[0076] Tensile strength / MPa Heat deformation temperature / ℃ 100℃ boiling time Applicable period / min Example 1 16.6 158 7h 81 Example 2 15.8 153 6h 27 Example 3 16.1 153 6h 25 Example 4 16.0 153 6h 25 Example 5 16.2 153 7.5h 36 Example 6 22.2 165 6.5h 119 Example 7 21.4 162 6.5h 124 Example 8 15.1 149 9h 85 Comparative Example 1 15.4 148 2h 29 Comparative Example 2 14.8 154 3.5h 87

[0077] It can be seen from the data results in Table 1 that the bismaleimide asparagine resin of the present invention has higher mechanical strength, higher heat resistance and better hydrolysis resistance than the existing asparagine resin, and the adjustment range of the applicable period is larger.

[0078] As described above, the basic principles, main features and advantages of the present invention are shown and described. Those skilled in the art should understand that the present invention is not limited by the above embodiments, which are only preferred embodiments of the present invention and cannot be used to limit the scope of the present invention. That is, equivalent changes and modifications made according to the scope of the present invention and the content of the specification should still be within the scope of the present invention. The scope of protection required by the present invention is defined by the attached claims and their equivalents.

Claims

1. Bismaleimide aspartame resin, characterized in that It has the structure shown in the following formula (1), Wherein, R1 is selected from C5-C6 cycloalkyl or C6-C12 substituted cycloalkyl, and R2 is selected from the divalent organic structure with an average molecular weight of 50-5000 which is inert to the isocyanate group at 100°C and remains after the primary amino group is removed from the divalent primary amine compound.

2. The bismaleimide aspartame resin according to claim 1, characterized in that The R1 is selected from cyclopentyl, C6-C10 substituted cyclopentyl, cyclohexyl or C7-C12 substituted cyclohexyl.

3. The bismaleimide aspartame resin according to claim 1, characterized in that The dibasic primary amine compound is selected from C2-C18 alkyl diamine, cyclopentane diamine, cyclohexane diamine or C6-C20 substituted cycloalkyl diamine.

4. The bismaleimide aspartame resin according to claim 1, characterized in that The dibasic primary amine compound is selected from C6-C12 alkyl diamines.

5. The process for preparing the bismaleimide aspartame resin according to any one of claims 1 to 4, characterized in that: It is obtained by reacting the mono-secondary amino asparagine resin represented by the following formula (2) with the dibasic primary amine compound through an imide reaction. wherein R1 has the same meaning as described above, and R3 and R4 are independently selected from C1-C4 alkyl groups.

6. The process for preparing the bismaleimide asparagine resin according to claim 5, characterized in that: The molar ratio of the mono-secondary amine aspartame to the di-primary amine compound is 1:0.3-0.

55.

7. The process for preparing the bismaleimide aspartame resin according to claim 6, characterized in that: The molar ratio of the mono-secondary amine aspartame to the di-primary amine compound is 1:0.45-0.

52.

8. The process for preparing the bismaleimide asparagine resin according to claim 5, characterized in that: A catalyst is further added into the imide reaction, and the catalyst is selected from C8-C18 fatty acid, benzotriazole or substituted benzotriazole.

9. The process for preparing the bismaleimide aspartame resin according to claim 8, characterized in that: The weight of the catalyst is 0.1-0.5% of the weight of the mono-secondary amino aspartic resin.

10. The process for preparing the bismaleimide aspartame resin according to claim 5, characterized in that: The R3 and the R4 are independently selected from methyl or ethyl.

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