Low viscosity self-thixotropic polyaspartate and preparation method and application thereof

Abstract

The application relates to the technical field of polyaspartic ester, and particularly discloses a low-viscosity self-thixotropic polyaspartic ester as well as a preparation method and application thereof. The preparation method of the low-viscosity self-thixotropic polyaspartic ester is that maleic acid ester and N, N-bis (2-aminoethyl) malonamide are used to synthesize the self-thixotropic polyaspartic ester. The self-thixotropic polyaspartic ester can be applied in paint to replace a thixotropic agent, so that the paint has relatively low viscosity and relatively high sag resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polyaspartic ester, more particularly, to a low-viscosity self-thixotropic polyaspartic ester, a preparation method and application thereof. BACKGROUND

[0002] The thixotropy of an object refers to a rheological phenomenon that the viscosity of a system changes with time when the system is agitated or subjected to other external forces, that is, a "touch" means a "change". The thixotropy of an object is due to the physical aggregation or electrostatic attraction of its internal particles to form hydrogen bonds, so that a network structure is gradually formed inside the fluid. Under the action of external shear force, the network structure changes with time on a micro scale, and exhibits shear thinning or shear thickening on a macro scale.

[0003] At present, thixotropic agents are mainly divided into inorganic thixotropic agents, organic thixotropic agents and composite thixotropic agents. Common inorganic thixotropic agents include fumed silica, common organic thixotropic agents include hydrogenated castor oil and polyamide wax, and composite thixotropic agents include organic bentonite. These thixotropic agents can be added to paints to prevent sagging, that is, when the paint is brushed, the paint is sheared to change the viscosity, and when it is left standing, the viscosity changes to thicken the paint, so that the filler is not easily affected by gravity and falls. However, these thixotropic agents will affect the performance of the paint to some extent, such as making the paint viscous, which is not conducive to brushing, and also increasing the cost of the paint.

[0004] One of the effective raw materials for paint is polyaspartic ester. General polyaspartic ester does not have a sag-preventing effect. After curing with isocyanate, aspartic polyurea made from general polyaspartic ester is used as paint. Although aspartic polyurea has a lone pair of electrons that can attract hydrogen to form a crosslinked network to some extent, the electron cloud of the amino group of aspartic polyurea is weakened due to the influence of the ester group, and the hydrogen atom is attracted by the oxygen atom, making it difficult to form a crosslinked network of hydrogen bonds with other molecules, and it is difficult to form a self-thixotropic effect. SUMMARY

[0005] In view of the fact that general polyaspartic ester does not have a sag-preventing effect and aspartic polyurea made from general polyaspartic ester and isocyanate is difficult to form a self-thixotropic effect, the present application proposes a low-viscosity self-thixotropic polyaspartic ester, a preparation method and application thereof to improve this phenomenon.

[0006] In a first aspect, the present application proposes a low-viscosity self-thixotropic polyaspartic ester, and adopts the following technical solution.

[0007] A low-viscosity self-thixotropic polyaspartic ester, the structural formula of the self-thixotropic polyaspartic ester is as follows:

[0008]

[0009] By adopting the technical scheme, the self-thixotropic polyaspartate has self-thixotropic properties, and application in paint can improve the sag resistance effect of the paint.

[0010] As an option of the low-viscosity self-thixotropic polyaspartate, each R in the structural formula is butyl or ethyl.

[0011] By adopting the technical scheme, the self-thixotropic polyaspartate has good self-thixotropic properties, and application in paint can improve the sag resistance effect of the paint.

[0012] In a second aspect, the application provides a preparation method of the low-viscosity self-thixotropic polyaspartate, and adopts the following technical scheme.

[0013] The preparation method of the low-viscosity self-thixotropic polyaspartate synthesizes the self-thixotropic polyaspartate by using maleate and N,N-bis(2-aminoethyl)malonamide.

[0014] By adopting the technical scheme, the two terminal amino groups of the N,N-bis(2-aminoethyl)malonamide are connected with the olefinic bond carbons of the maleate, to obtain the self-thixotropic polyaspartate.

[0015] As an improvement of the preparation method of the low-viscosity self-thixotropic polyaspartate, the N,N-bis(2-aminoethyl)malonamide is obtained by dissolving N,N-bis(2-aminoethyl)malonamide dihydrochloride in water, and then evaporating water to obtain the N,N-bis(2-aminoethyl)malonamide.

[0016] By adopting the technical scheme, the hydrochloric acid in the N,N-bis(2-aminoethyl)malonamide dihydrochloride is removed to obtain the alkaline N,N-bis(2-aminoethyl)malonamide, and the synthesis reaction is performed by using the alkaline N,N-bis(2-aminoethyl)malonamide and the maleate, which has higher reaction efficiency than that of using the acidic N,N-bis(2-aminoethyl)malonamide dihydrochloride and the maleate.

[0017] As an improvement of the preparation method of the low-viscosity self-thixotropic polyaspartate, the water evaporation is heating the N,N-bis(2-aminoethyl)malonamide dihydrochloride aqueous solution to 50-100 DEG C to evaporate water; and after evaporating water, anhydrous sodium sulfate is added, and the oil-like N,N-bis(2-aminoethyl)malonamide is obtained by filtration.

[0018] By adopting the technical scheme, the hydrochloric acid is evaporated together when the water is evaporated at 50-100 DEG C, and the anhydrous sodium sulfate can absorb water to obtain the dry N,N-bis(2-aminoethyl)malonamide.

[0019] As an improvement to the preparation method of the low-viscosity self-thixotropic polyaspartic acid ester, the molar ratio of the maleate ester and the N,N-bis(2-aminoethyl)malonamide:dihydrochloride is (1.9~2.1):1.

[0020] By adopting the above technical solution, two maleic acid esters are bonded to both ends of N,N-bis(2-aminoethyl)malonamide to obtain self-thixotropic polyaspartic acid ester.

[0021] As an improvement to the preparation method of the low-viscosity self-thixotropic polyaspartic acid ester, the obtained N,N-bis(2-aminoethyl)malonidamide is added dropwise to maleic acid ester and reacted at 60-80°C for 48-96 hours to obtain the self-thixotropic polyaspartic acid ester.

[0022] By adopting the above technical solution, it is beneficial to first bind one maleate ester to N,N-bis(2-aminoethyl)malonamide, thereby reducing the occurrence of side reactions when two N,N-bis(2-aminoethyl)malonamides bind one maleate ester. After a reaction of 48h to 96h, a self-thixotropic polyaspartic acid ester with one maleate ester bound to each end of N,N-bis(2-aminoethyl)malonamide is obtained.

[0023] Thirdly, this application proposes an application of a low-viscosity self-thixotropic polyaspartic acid ester, and adopts the following technical solution.

[0024] Application of a low-viscosity self-thixotropic polyaspartic acid ester obtained by the preparation method described above, wherein the self-thixotropic polyaspartic acid ester is used in coatings in place of a thixotropic agent.

[0025] By adopting the above technical solution, the coating has anti-sagging properties. As one of the effective components of the coating, self-thixotropic polyaspartic acid ester does not require the addition of thixotropic agents, does not increase the viscosity of the coating, and also reduces material costs.

[0026] As an improvement to the application of this low-viscosity self-thixotropic polyaspartic ester, the self-thixotropic polyaspartic ester and non-thixotropic polyaspartic ester are mixed uniformly at a mass ratio of 1:(6-8) to obtain Agent A of the coating.

[0027] By adopting the above technical solution, self-thixotropic polyaspartic acid ester and non-thixotropic polyaspartic acid ester have similar properties and can be miscible to obtain a homogeneous material. The mixture after miscibility at this mass ratio has suitable self-thixotropic properties and is suitable for use as a coating.

[0028] Among them, the non-thixotropic polyaspartic ester is a general polyaspartic ester, one of which has the following structural formula:

[0029]

[0030] As an improvement of the application of the low viscosity self-thixotropic polyaspartic ester, the A agent and the B agent are mixed in a mass ratio of 1:(1-1.1) to obtain a self-thixotropic aspartic polyurea coating; the B agent is an isocyanate.

[0031] By adopting the technical scheme, the aspartic polyurea is generated by the reaction of the polyaspartic ester and the isocyanate, the aspartic polyurea has a relatively low viscosity, and has a relatively high sag resistance.

[0032] In summary, the low viscosity self-thixotropic polyaspartic ester and the preparation method and application thereof have the following beneficial effects:

[0033] The preparation condition of the low viscosity self-thixotropic polyaspartic ester is under normal pressure, and the addition reaction can be carried out at 60-80°C without adding other reagents, and the reaction is carried out under alkaline conditions, and the reaction efficiency is high.

[0034] The low viscosity self-thixotropic polyaspartic ester has a self-thixotropic property, can be applied in a coating instead of a thixotropic agent, and makes the coating have a relatively low viscosity and a relatively high sag resistance. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The reaction formula for the addition reaction of maleate and N,N-bis(2-aminoethyl)malonamide. DETAILED DESCRIPTION

[0036] The low viscosity self-thixotropic polyaspartic ester and the preparation method and application thereof are specifically described below through examples and comparative examples.

[0037] Some raw material information used in the following examples and comparative examples is as follows.

[0038] The maleate is from Shenzhen Feiyangte New Material Co., Ltd.

[0039] The N,N-bis(2-aminoethyl)malonamide: dihydrochloride is from MolMall Sarl Co., Ltd., Switzerland.

[0040] The non-thixotropic polyaspartic ester is polyaspartic ester F520, and the polyaspartic ester F520 is from Shenzhen Feiyangjunyan New Material Co., Ltd.

[0041] The defoaming agent Airex 931 is from Evonik Special Chemicals (Shanghai) Co., Ltd.

[0042] The isocyanate is an HDI trimer, and the HDI trimer is from Shenzhen Feiyangjunyan New Material Co., Ltd.

[0043] The fumed silica is from WACKER (Shanghai) Co., Ltd.

[0044] Example 1

[0045] Take 130.5g (i.e. 0.5mol) N,N-bis(2-aminoethyl)propanediamide: dihydrochloride and dissolve it in water, heat to 70℃ and evaporate the water, then add anhydrous sodium sulfate to the remaining liquid, stir to make the anhydrous sodium sulfate fully absorb water, then filter to obtain an oily substance. The oily substance is N,N-bis(2-aminoethyl)propanediamide, whose structural formula is as follows:

[0046]

[0047] Take 76g (i.e. 1mol) maleate, heat to 70℃, and under the condition of continuous stirring, add the above oily substance dropwise into the maleate, the structural formula of which is as follows wherein R is ethyl.

[0048] After the dropwise addition is completed, the reaction is carried out for 72h, and the reaction formula of N,N-bis(2-aminoethyl)propanediamide and maleate is as shown in Figure 1 After the addition reaction, a liquid self-thixotropic polyaspartate is obtained.

[0049] Application Example 1

[0050] Under stirring, mix 50g of the self-thixotropic polyaspartate prepared in Example 1 with 350g of polyaspartate F520, add 1g of defoaming agent Airex 931, the stirring speed is 2000r / min, and the stirring time is 0.5h, to prepare a self-thixotropic polyaspartate coating. Mix the self-thixotropic polyaspartate coating with isocyanate (HDI trimer) at an equivalent ratio of 1:1.05 to obtain a sag-resistant aspartic polyurea coating. The self-thixotropic polyaspartate coating and the isocyanate will slowly undergo a curing reaction, so they are mixed just before spraying.

[0051] Comparative Application Example 1

[0052] A thixotropic polyaspartic ester coating was prepared by adding 400 g polyaspartic ester F520, 1 g antifoam agent Airex 931 and 2 g fumed silica as thixotropic agent under stirring at a stirring speed of 2000 r / min for 0.5 h. The thixotropic polyaspartic ester coating was mixed with isocyanate (HDI trimer) at an equivalent ratio of 1 : 1.05 to obtain a sag-resistant aspartic polyurea coating. The thixotropic polyaspartic ester coating and isocyanate will undergo a slow curing reaction, so they are mixed just before spraying.

[0053] Comparative Application Example 2

[0054] A polyaspartic ester coating was prepared by adding 400 g polyaspartic ester F520, 1 g antifoam agent Airex 931 under stirring at a stirring speed of 2000 r / min for 0.5 h. The polyaspartic ester coating was mixed with isocyanate (HDI trimer) at an equivalent ratio of 1 : 1.05 to obtain an aspartic polyurea coating. The polyaspartic ester coating and isocyanate will undergo a slow curing reaction, so they are mixed just before spraying.

[0055] Test Example 1

[0056] The sag-resistant aspartic polyurea coating prepared in Application Example 1, the sag-resistant aspartic polyurea coating prepared in Comparative Application Example 1 and the aspartic polyurea coating prepared in Comparative Application Example 2 were tested for viscosity and sag resistance.

[0057] The viscosity test was performed in accordance with ISO 2884-2.

[0058] The sag resistance evaluation standard was GB / T9264-2012.

[0059] The test results are as follows.

[0060] Application Example 1: the viscosity was 956 mPa / s, and the sag film thickness evaluated by sag resistance was 70 pm.

[0061] Comparative Application Example 1: the viscosity was 1200 mPa / s, and the sag film thickness evaluated by sag resistance was 67 pm.

[0062] Comparative Application Example 2: the viscosity was 1056 mPa / s, and the sag film thickness evaluated by sag resistance was 32 pm.

[0063] The test results above show that the anti-sagging aspartic polyurea coating prepared in Example 1 has low viscosity and strong anti-sagging effect. Therefore, the self-thixotropic polyaspartic ester prepared in Example 1 possesses self-thixotropic properties and can be used to replace conventional thixotropic agents. Furthermore, the self-thixotropic polyaspartic ester prepared in Example 1, as an effective component of the coating, can react with other components to cure and form a paint film. Using the scheme of Example 1, without the need to add additional thixotropic agents, a coating with lower viscosity and stronger anti-sagging properties than one with added conventional thixotropic agents under the same conditions can be obtained, demonstrating good market prospects.

[0064] The above are merely some embodiments of this application. The scope of protection of this application is not limited to the above embodiments. For those skilled in the art, any improvements and modifications made without departing from the inventive design of this application should also fall within the scope of protection of this application.

Claims

1. A low viscosity self-thickening polyaspartate, characterized in that, The self-thixotropic polyaspartate has the following structural formula: ； Each R in the structural formula is butyl or ethyl.

2. A process for the preparation of a low viscosity self-thickening polyaspartate according to claim 1, characterized in that, The self-thixotropic polyaspartate is synthesized by using maleate and N,N'-bis(2-aminoethyl)malonamide.

3. The process for the preparation of a low viscosity self-thixotroping polyaspartic ester according to claim 2, characterized in that, The N,N'-bis(2-aminoethyl)malonamide is obtained by dissolving N,N'-bis(2-aminoethyl)malonamide dihydrochloride in water, and then evaporating water to obtain the N,N'-bis(2-aminoethyl)malonamide.

4. The process for the preparation of a low viscosity self-thixotroping polyaspartic ester according to claim 3, characterized in that, The water evaporation is to heat the aqueous solution of N,N'-bis(2-aminoethyl)malonamide dihydrochloride to 50-100 DEG C to evaporate water; after the water evaporation, anhydrous sodium sulfate is added, and the oil-like N,N'-bis(2-aminoethyl)malonamide is obtained by filtration.

5. Process for the preparation of a low viscosity self-thixotroping polyaspartic ester according to claim 3 or 4, characterized in that, The molar ratio of the maleate and the N,N'-bis(2-aminoethyl)malonamide dihydrochloride is (1.9-2.1):

1.

6. The process for the preparation of a low viscosity self-thixotroping polyaspartic ester according to claim 3 or 4, characterized in that, The obtained N,N'-bis(2-aminoethyl)malonamide is added dropwise into maleate, and reacted at 60-80 DEG C for 48-96 h to obtain the self-thixotropic polyaspartate.

7. Use of a low viscosity self-hardenable polyaspartic ester obtained by the process according to any one of claims 2 to 6, characterized in that, The self-thixotropic polyaspartate is used in paint instead of thixotropic agent.

8. Use of a low viscosity self-hyoertraphic polyaspartate according to claim 7, characterized in that, The self-thixotropic polyaspartate and non-thixotropic polyaspartate are mixed uniformly at a mass ratio of 1:(6-8) to obtain the A agent of the paint.

9. Use of a low viscosity self-hindering polyaspartic ester according to claim 8, characterized in that The A agent and B agent are mixed at a mass ratio of 1:(1-1.1) to obtain the self-thixotropic aspartic polyurea paint; the B agent is isocyanate.

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