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Performance comparison of 2,2-dimethylol butyric acid (DMBA) and 2,2-dimethylol propionic acid (DMPA)
Release time:
2019-11-11
1. product characteristics
2,2-Dihydroxymethyl Butanoic Acid
Molecular formula: C6H12O4, molecular weight: 148.16,CAS registration mark:[10097-02-6]
英文名称： Dimethylolbutanoic acid [2,2-Bis(hydroxymethyl)butyric Acid]
White crystalline powder, hygroscopic at high relative humidity. The melting point is 107~115 ℃ (high purity is 112~117 ℃), and the density is 1.263g/cm3. Soluble in water. The solubilities in acetone, methyl ethyl ketone and methyl isobutyl ketone at 20 ° C. are 15g/100g, 7g/100g and 2g/100g, respectively, and the solubilities at 40 ° C. are 44g/100g, 14g/100g and 7g/100g, respectively.
The toxicity was low, and the acute oral poisoning value of LD50 in rats was> 2000 mg/kg.
Solubility data unit g/100g solvent
| Temperature |
Acetone |
methyl ethyl ketone |
methyl isobutyl ketone |
| 20℃ |
15(1) |
7(0.4) |
2(0.1) |
| 40℃ |
44(2) |
14(0.8) |
7(0.5) |
The solubility of DMBA in water at 20 ℃ is 48%, the solubility of DMPA in water is 11%, and () is the solubility of DMPA.
2.
Main technical indicators of product quality
| Project |
Indicators |
|
| 2,2-Dihydroxymethylbutyric acid (DMBA) |
2,2-Dimethylolpropionic Acid (DMPA) |
|
| Appearance |
White solid particles |
White solid particles |
| Content% ≥ |
99 |
99 |
| Moisture% ≤ |
0.5 |
0.5 |
| Hydroxyl value mgKOH/g |
728～782 |
810～860 |
| Acid value mgKOH/g |
370～375 |
414.2～418.3 |
| Melting point ℃ |
108～115 |
≥ 180 |
| Water content% ≤ |
0.3 |
0.3 |
| Ash content% ≤ |
0.03 |
0.03 |
| Residual aldehyde content% ≤ |
0.03 |
0.03 |
| Iron (Fe) content ppm ≤ |
5 |
5 |
| Sodium (Na) content ppm ≤ |
150 |
50 |
| (K) content ppm ≤ |
10 |
10 |
| acetone-triethylamine dissolution test |
Clarification and transparency |
Clarification and transparency |
Main uses and advantages of 3. products
2,2-dimethylol butyric acid is a kind of both hydroxyl and carboxyl groups, unique multi-functional hindered diol molecules, free acid groups in the neutralization with alkali, can actively improve the resin water solubility or dispersion performance; the introduction of polar groups, improve the adhesion of coatings and synthetic fiber dyeing performance; increase the coating alkali solubility. Can be applied to water-soluble polyurethane systems, water-soluble alkyd resins and polyester resins, epoxy ester coatings, polyurethane elastomers and powder coatings.
It can also be used in leather materials, liquid crystal, ink, food additives and adhesive chemical industry, especially in the manufacture of water emulsion polyurethane and leather finishing agent, it is not only a chain extender, but also can make polyurethane get good self emulsifying performance, can greatly improve the stability of polyurethane water emulsion.
2,2-dimethylol butyric acid is a multi-functional compound containing two primary hydroxyl groups and a carboxyl group in the molecule. The molecule has the characteristics of alcohols and acidic compounds, and its lipophilic carbon skeleton structure and hydrophilic functional group structure make it have unique solubility properties, and become an excellent crosslinking agent and fine chemical intermediate. Using this characteristic, 2,2-dimethylol butyric acid can be used to prepare water-soluble polyurethane, polyester, epoxy resin and so on. It is a new green chemical. In addition, since 2,2-dimethylol butyric acid has a low melting point, is easily soluble in a ketone-based solvent represented by acetone, and is excellent in workability in the production of aqueous polyurethane, its use is expanding even in fields other than aqueous systems.
DMBA is a neopentyl carboxylic acid with two active hydroxymethyl groups, so it can be used as a synthetic water-based polymer system, and can be widely used in water-soluble polyurethane, polyester, epoxy resin and so on. DMBA has better solubility than DMPA in different solvents, so the work efficiency can be greatly improved. DMBA is regarded as a new generation of green and environmentally friendly chain extender and internal emulsifier for waterborne polyurethane, and produces waterborne polyurethane adhesives without the use of organic solvents and zero organic residues. There are no problems such as high melting point, slow dissolution, long reaction time, high energy consumption, poor product performance, need to add organic solvents, and large amount of residual solvents. Can also be used for the manufacture of waterborne epoxy resin, polyester and other adhesives. At present, waterborne polyurethane, waterborne resins, waterborne adhesives, waterborne coatings and other waterborne products best multi-purpose modification additives (hydrophilic chain extender), as a monomer, modification process, dimethylol butyric acid (DMBA) without adding any organic solvent (replaced by water), the production process is more simple, stable performance, the best effect. Among them, dimethylol propionic acid (DMPA) is widely used in the field of water because of its superior cost performance.
The dimethylol carboxylic acid hydrophilic chain extenders currently used are mainly DMPA and DMBA, of which DMPA is used earlier and is the most commonly used one. Although it has many advantages, it still has many disadvantages, mainly its own high melting point (180 ℃-185 ℃), it is difficult to heat melting, which requires the addition of organic solvents such as N-methyl pyrrolidone (NMP), N,N-dimethyl amide (DMF), acetone, etc., and NMP has a high boiling point, it is difficult to remove after the preparation of APU. Moreover, the solubility of DMPA in acetone is small, and a large amount of acetone needs to be added in the synthesis process, which not only wastes energy but also brings security risks. Therefore, the use of DMPA not only produces high energy consumption, but also easily causes organic residues in the product. Because of its special molecular structure, DMBA does not need to consume a little solvent in the synthesis process, which not only shortens the reaction time, not only greatly improves the work efficiency, but also reduces energy consumption and saves energy.
Compared with DMBA and DMPA, DMBA has the following obvious advantages:
(1)DMBA has better solubility in organic solvents.
Table 2: Solubility data of DMBA and DMPA in different solvents at different temperatures
| Serial Number |
Temperature |
Acetone |
|||||
| DMBA |
DMPA |
DMBA |
DMPA |
DMBA |
DMPA |
||
| 1 |
20 |
15 |
1 |
7 |
0.4 |
2 |
0.1 |
| 2 |
40 |
44 |
2 |
14 |
0.8 |
7 |
0.5 |
Solubility: unit g/100g solvent
The solubility of DMBA in water is 48% and that of DMPA is 12%.
At the same time, DMBA has a low melting point of 108 ℃ ~ 115 ℃;
Because DMBA has excellent solubility and low melting point, it does not need solvent or less solvent in the process of synthesizing waterborne polyurethane emulsion.
Xie Wei et al. in the "DMBA-based waterborne polyurethane emulsion synthesis research" shows that: the use of DMBA as a hydrophilic chain extender, the use of chain extension process, the whole reaction process 6h can be basically completed, without solvent, making the product environmentally friendly, and without desolubilization, to avoid waste.
Liu Dubao and others in the "solvent-free waterborne polyurethane synthesis and performance research" shows that: in the process of synthesizing waterborne polyurethane with DMBA, do not add a little solvent can complete the whole reaction process, and the reaction results with the formula design.
(2) High reaction rate, fast reaction speed and low reaction temperature.
Synthesis of polyurethane prepolymer reaction time is short, generally as long as 50-60 minutes, and DMPA is 150-180 minutes. This is because the DMBA structure than DMPA more than a methylene group, the distance between the carboxyl group and the methylene group increases, the carboxyl group and the isocyanate steric hindrance is reduced, so that the reaction rate increases.
(3) for waterborne polyurethane emulsion, the particle size is finer and the distribution is narrow, the film performance is excellent, and the gloss is high.
In "Study on Synthesis and Properties of Solvent-free Waterborne Polyurethane", Liu Dubao et al. used dihydroxybutyric acid (DMBA), isophorone diisocyanate (IPDI), polyoxypropylene glycol (PPG-220) and other main raw materials to synthesize solvent-free waterborne polyurethane resin by prepolymer method. Compared with WPU synthesized by DMPA, the specific data are shown in Table 3.
Table 3:DMBA, DMPA polyurethane emulsion performance comparison:
| No. |
Tensile strength/（MPa） |
Modulus/(MPa) |
feel |
Gloss |
|
| P-1 |
7.6 |
464 |
4.6 |
Good. |
78 |
| P-2 |
9.4 |
495 |
5.4 |
General |
85 |
| B-3 |
33.5 |
1290 |
17.5 |
Good. |
84 |
| B-2 |
46.7 |
1186 |
19.7 |
better |
90 |
Note: P-1 and P-1 represent 1.0% and 2.0% of carboxyl groups in DMPA, and B- 1 and B- 1 represent 1.0% and 2.0% of carboxyl groups in DMBA.
Liu Dubao and others believe that the tensile strength and elongation at break of DMBA polyurethane emulsion are higher than those of DMPA polyurethane. The reasons are: first, the molecular structure of DMBA, the huge side chain-CH2COO-hinders the aggregation of polyurethane hard segments, and the poor packing degree of hard segments makes the hard segments have high solubility in the soft segment matrix and reduces the hard segments in the hard segment micro region. These factors will lead to the decrease of modulus, however, a low modulus leads to a larger elongation at break, which in turn leads to further stress crystallization in the soft segment, resulting in a higher tensile strength. Second, DMBA has a lower melting point than DMPA, and DMBA is easy to melt in polyols, so DMBA can react completely according to the formula in the same time, and because only a part of DMPA dissolves and reacts, DMBA has a larger molecular weight than DMPA and has better mechanical properties. The reason for the higher gloss of DMBA than DMPA may be due to the better hydrophilicity of DMBA, resulting in smaller particle size and more uniform particles of the emulsion.
Dimethylolbutyric acid can be easily methylated or esterified by the action of two primary hydroxyl groups without protecting the third carboxyl group, and then based in aqueous ammonia to make it water soluble. The product can be widely used in polyurethane, polyester, epoxy resin and so on. In terms of solubility, DMBA has its own unique solubility, which can greatly improve work efficiency.
At present, the aqueous polyurethane is mainly anionic self-emulsifying, the hydrophilic chain extender is mostly DMPA, the salt forming agent is triethylamine (TEA), and the polyurethane emulsion with moderate viscosity and good stability can be obtained within the range of TEA/DMPA0.73-0.78. Compared with DMPA, the preparation of polyurethane emulsion with DMBA as anionic internal emulsifier has the following characteristics: ① the melting point of DMBA is 105 ℃, so it can be melted/dissolved in polyol at this temperature; ② the reaction time (about 60-60min) for the synthesis of polyurethane prepolymer with DMBA is much smaller than that of DMPA (about 150-180min);③ The tensile strength and elongation at break of polyurethane emulsion film prepared by DMBA before and after water absorption are larger than those prepared by DMPA; ④ APU emulsion prepared by DMBA as internal emulsifier has large particle size and narrow distribution, therefore, the preparation of polyurethane emulsion with DMBA as anionic emulsifier has a good application prospect.
Comparison of using DMBA and DMPA:
| Types of Polyols Used |
polyether polyol |
polycarbonate polyol |
|||
|
|
|
DMBA |
DMPA |
DMBA |
DMPA |
| Ingredients |
H12MDImole ratio |
1.94 |
1.94 |
1.94 |
1.94 |
| PTMG2000 |
1 |
1 |
|
|
|
| PCD2000 |
|
|
1 |
1 |
|
| DMBA |
0.58 |
|
0.58 |
|
|
| DMPA |
|
0.58 |
|
0.58 |
|
| TEA (Ethyltriamine) |
0.46 |
0.46 |
0.46 |
0.46 |
|
| EDA |
0.009 |
0.009 |
0.009 |
0.009 |
|
| NVP wt% tosolid |
10 |
10 |
20 |
20 |
|
| Dispersion properties |
Solid content wt% |
33.7 |
33.1 |
32.3 |
32.7 |
| Viscosity mpa.s/25 ℃ |
78 |
50 |
57 |
51 |
|
| PH value |
8.6 |
8.6 |
7.6 |
7.8 |
|
| Mechanical properties |
50% modulus Mpa |
7.4 |
9.2 |
6 |
5.1 |
| Tensile strength Mpa |
35.6 |
28.8 |
24.9 |
16.7 |
|
| Elongation% |
573 |
439 |
422 |
307 |
|
| Water resistance
|
50% modulus Mpa |
4 |
4.6 |
4.1 |
3.3 |
| Tensile strength Mpa |
18.6 |
12.2 |
21.4 |
17.4 |
|
| Elongation% |
573 |
455 |
518 |
529 |
|
| Absorption Rate% |
4.3 |
4.2 |
4.2 |
5.3 |
|
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