Methyl cyclodiamine (Baxxodur®EC 210) - an epoxy curing agent with excellent aminomethylate stability

Epoxy-based industrial protective coatings have excellent chemical and mechanical properties. However, commonly used amine curing agents can easily react with carbon dioxide and moisture in the atmosphere, forming amino acids. When amino methamphetamine accumulates on the surface, it will cause foggy and inter-coating adhesion problems
the
. A resin curing agent containing methyl cyclodiamine (MCDA, Baxxodur® EC 210) in the addition has high aminomethyl acid stability compared to the additions containing isofronedamine (IPDA) and methylhamide (MXDA). This feature is further validated in coating testing, where the coating formulation containing MCDA has excellent gloss. In addition, different analytical techniques, such as differential scanning heat and fluidization, are used to evaluate the curing behavior, mechanical properties and thermal properties of MCDA, IPDA, and MXDA curing systems. Overall, experiments have shown that MCDA is an attractive basic chemical component in industrial coating systems that make epoxy.
The
of industrial protective coatings is to protect surfaces such as concrete from degradation in an eroded environment. Epoxy resin systems are ideal for this type of protective use because of their good adhesion, excellent mechanical and thermal properties, and good chemical resistance. Epoxy resins can be cured with a variety of co-reactants such as amines, phenols, thiols and pyric acid, so they have a wide range of operations and good performance. Lipocycline damine curing agents are widely used in flooring applications, because they are not only good in operation, but also have good final properties, such as fast curing, low viscosity, low toxicity, good adhesion and high color stability. In addition, lipid ring damines are particularly suitable for use in places where low temperature curing or where bonding with wet concrete is required. In floor applications
amines are usually used in the form of an add-on, in which a large amount of amines and epoxy resins are used to pre-react. Generally speaking, the addition is not easily cloudy, because the content of beetamine in the molecule is relatively reduced, thereby reducing the moisture absorption of the add-on. When beamine reacts with carbon dioxide and water in the atmosphere, the formation of amino acids can lead to foggy. In addition to reducing foggy, amine additions are also less corrosive and volatile. However, these advantages come at a cost, as the addition effect significantly increases the viscosity of the coating.
In order to reduce viscosity, amine supplements are usually made with plasticizers such as solvents or BnOH, which, in addition to being used as adhesives, accelerate the reaction of epoxy resins and amines at or below room temperature.
methyl cyclohexamine (MCDA) is a lipocycline-type epoxy curing agent, the same as isofolone dhiamine (IPDA) 3, ideal for floor applications; IPDA is known for its low viscosity, but MCDA has a lower viscosity than IPDA. MCDA consists of two positional isomer, i.e. 2, 4 and 2, 6-MCDA, with four and three stereo isomer, respectively (Figure 1). IPDA and MCDA are prone to react with epoxy resins at or below room temperature, and their low viscosity increases flexibility in preparation and/or extended operating windows.
Figure 1. The differences between
the two lipid cycloamine supplements, IPDA and MCDA, and between MCDA and an aromatamine-MXDA supplement, will be explored in this paper. These three amines have advantages and disadvantages in curing performance, thermal properties and appearance. The two amine curing agents used in this study are shown in Figure 1.
experiment

bisphenol A epoxy resin (DGEBA) is a product of Leuna-Harze GmbH (Epilox® A 19-03, epoxy equivalent 184 g/mol). Isofrogen diamine (Baxxodur® EC 201, active amine equivalent 42.6 g/mol) and methyl cyclodiamine (Baxxodur® EC 210, active amine equivalent 32 g/mol) are BASF Europe (BASF SE) products. Interamerphetamine (active amine equivalent 34 g/mol) was purchased from Mitsubishi Gas Chemical Company.
was purchased from Honeywell. All chemicals have been used since the beginning.
addition synthesis
the amine erythamine erythramine (Figure 2) using excessive amine synthesis. DGEBA has a molar ratio of 1:16, 1:8, or 1:2.5. Among them, add a BnOH plus of 1:2.5 at the molar ratio to keep the viscosity within the effective range. For this type of addition, BnOH and damines of the same equivalent (weight) are used. The next experiment was an example of a synthetic add-on with a molar ratio of 1:2.5 (DGEBA/MCDA). McDA (175g, 1.37mol) and BnOH (175g) are combined in a 1 liter round bottom combo protected by nitrogen. Then add the DGEBA (200 g, 0.55 mol) and stir to promote a full reaction. Although no active heating is taken, the temperature of the reaction material remains below 100 degrees C.
Figure 2. Preparation of an idealized add-on
active DEGBA add-on mixture containing MCDA
To cure DGEBA with a prepared add-on or add-on-BnOH mixture, a chemical measurement ratio of 1:1 can be used to biopic the reaction mixture with an epoxy group with a chemical metering ratio of 1:1.
the epoxy add-on or epoxy-BnOH mixture is stirred at a speed of 2000 rpm through the propeller mixer for 1 minute. The differential scanning thermal method (DSC) and fluidity experiments are carried out immediately after preparation, and samples for the measurement of D-type hardness and spectral gloss are prepared.
Method
Using DSC (204 F1 Pheonix, Netzsch), the reaction and thermal curve (Start temperature (To), peak temperature (Tp), glass transfer temperature (Tg)) are measured at room temperature (23 degrees C) starting at room temperature (23 degrees C).
using a conventional control shear stress flat plate rheometer (MCR 301, Anton Paar) with a plate diameter of 15 mm and a clearance distance of 0.25 mm, the flow curve (life and time of life and time) at 23 degrees C and 75 degrees C is measured in rotation mode (pot life) or oscillation force (gel time). The pot life is measured at the time required to reach a viscosity of 10,000 mPas at the specified temperature. Gel points are defined as the intersection of storage and loss of mods, while gel time is defined as the time it takes to add a curing agent to the reaction mixture to reach the gel point.
to measure shore D hardness, we injected a 3 g reaction mixture into an aluminum pot with an internal diameter of 30 mm. The system is cured at 10 degrees C (65% relative humidity) or 23 degrees C (ambient atmosphere). An hourly Shore D hardness measurement is performed on samples with a thickness of 35-36 mm in accordance with DIN ISO 7619 1.
the easyness of amino methamphetamine formation is visually observed by putting a 3g add-on or add-on-BnOH mixture into a container with a 2×3-well plate with a diameter of 35 mm
The add-on or add-on-BnOH mixture is then stored for a total of 48 hours at a temperature of 23 degrees C and a relative humidity of 50%, and photographed after 2, 4, 6, 8, 16, 24 and 48 hours, respectively. By visual inspection, the observed white sediment or uneven surface is amino acid.
apply the active epoxy plus-BnOH mixture to a black matte surface with a 500 m scraper bar for gloss testing. It was cured for 69 hours at 8 degrees C to obtain the curing film. Using Byk Gardner's micro-TRI (20-degree, 60-degree, 85-degree) gloss gauge, the gloss is measured at a 20-degree angle according to the ASTM D523 standard.
results and discussion
addition production
DGEBA was slowly added to the excess amine, synthesized into nine additions (Table 1). The additions are not separated or purified after synthesis, and all synthetic systems are a mixture of DEGBA-damine additions and residual damines. The use of BnOH can make the epoxy-damine mixture ratio of the three two amine substances as low as 1:2.5. If solvents are not used, the minimum mixing ratio can be 1:8.
Table 1. Add-on and add-on-BnOH Mixture Summary Table
there performance
compared to pure ddiamines, the addition reactions of MCDA, IPDA and MXDA result in a slight decrease in the starting temperature and the heating peak temperature and a slight increase in Tg when using a chemical metered mixing ratio without BnOH. Both MCDA and IPDA contain two beetamines, resulting in similar polymer main chain structures and Tgs. Compared to MXDA, MXDA's main chain is more flexible and lower Tg due to the ethyl between amino and aromatic amino acids. As expected, Tg can be reduced by 40-70 degrees C using BnOH's add-on. Table 2 summarizes the DSC results. The DSC values for all pure dDamines are recorded in the table in good consistency with those previously reported. Table 2

The thermal properties of DGEBA cured with the addition and the addition-BnOH mixture
Observations show that the DGEBA rheodient curve cured by MCDA-add-on has a large difference compared to the DGEBA rheoid curve cured with IDDA-plus or MXDA-plus. For example, MXDA-A16, made with DGEBA, has the lowest viscosity at room temperature, followed by MCDA-A16 and finally IPDA-A16 (Table 3). At a high temperature of 75 degrees C, the lowest viscosity of MCDA-A16 made with DGEBA is very similar, while the viscosity of MXDA-A16 and IPDA16 pluss made with DGEBA is very similar. In addition, different viscosity properties of DGEBA formulations formulated with different add-ons were found. For example, as shown in Figure 3, although the initial viscosity of the MCDA-A16 formula is higher than that of the MXDA-A16, the formulation viscosity of the MCDA-A16 is increased more slowly and therefore has a longer application period. The application period is affected by two factors, namely the starting viscosity and the reaction rate, and even though the starting viscosity of MXDA-A16 is lower, the reaction rate is faster than that of MCDA-A16. This trend is also reflected in gel time, where the preparation of the MXDA-A16 has been observed to have the shortest time to reach the gel point, followed by IIDA-A16 and then MCDA-A16. Since all A16 add-ons theoretically function the same, MXDA's gel time is fast, showing that it has a faster reaction rate.
3. The rheary properties of DGEBA hardened with a addition and a bnOH blend.
3. A map of the viscosity of DGEBA cured with a mixture of add-ons and additions-BnOH at a) 23 degrees Celsius and b) 75 degrees C. DGEBA viscosity data cured with IPDA-A8 are not reported here because the formulation starts with a viscosity of more than 10,000mPas.
The D hardness of the D-hardness is formed
under two different atmospheric conditions: 10 degrees C (65% relative humidity) or 23 degrees C (ambient atmosphere), we measured the progress of the Shore D hardness of the synthetic add-on with the DGEBA. The formation of shore D hardness also depends on two factors: the rate of accumulation of network density and the stiffness of the polymer main chain. Here, we compare amine substances with similar hardness and official energy, so the difference in the hardness of the Shore D type will depend mainly on the reaction rate. Unsurprisingly, it has been observed that the addition containing MXDA reached shore D hardness 80 much earlier than the addition containing IPDA or MCDA (Table 4, Figure 4). IpDA has better hardness formation and table drying time than MCDA at 10 degrees C, but IPDA and MCDA add-ons have the same characteristics when the temperature is raised to 23 degrees C.
Figure 4. DGEBA is hardened by MCDA-A16, IPDA A16 and MXDA-A16 pluss at 23 degrees C (ambient atmosphere) at different times.
table 4. DGEBA's D and sticky development hardened with a mixture of add-ons and add-ons-BnOH.
the stability of amino
beetamine easily reacts with atmospheric carbon dioxide and water vapor to form amino methamphetamine. Aminomethy acid tends to accumulate on the surface of the reacting substance, forming a cloud. Foggy can adversely affect glossiness, color, and adhesion between coatings. In order to determine the stability of amino acid formation, we use two different methods to determine different additions. First, without the use of DGEBA, the pure add-on or add-on-BnOH mixture is placed in an artificial climate chamber with a temperature of 23 degrees C and a relative humidity of 50%. The formation of amino methamphetamine is visually detected by white precipitation or surface unevenness (Figure 5).
5. Aging for 48 hours at a relative humidity of 23 degrees C and 50% of the bnOH mix. The same was found of IPDA-A2.5-BnOH when the presence of white precipitation or surface irregular amino acid was visually detected.
only two hours after the device is placed, a large amount of amino acid formation can be found in MXDA-A16, and a large amount of amino acid formation is also found in IPDA-A16 within 16 hours.
, although the MCDA A16 became slightly cloudy after 16 hours, after 48 hours, the precipitation of amino acid was not found in the MCDA A16. The addition containing BnOH was also tested. Amino methamphetamine was first detected in MXDA-A2.5-BnOH after 8 hours, IPDA-A2.5-BnOH 24 hours later, and MCDA-A2.5-BnOH was not observed even after 48 hours.
6. Aging at 23 degrees C and 50% relative humidity