Anti-sagging adjuvant and method for preparing the same

Abstract

The present application provides a kind of anti-sagging auxiliary and its preparation method. Specifically, the present application provides an anti-sagging auxiliary, which is prepared by the following method: (a) mixing a carrier resin, a solvent and fumed silica, and dispersing them to a fineness of <20 microns to obtain a fumed silica-modified resin; (b) mixing the fumed silica-modified resin with an amine substance, adding an isocyanate compound and dispersing uniformly to obtain the anti-sagging auxiliary.

Description

Technical Field

[0001] This invention belongs to the field of coating additive synthesis, and specifically relates to an anti-sagging additive and its preparation method. Background Technology

[0002] When applying polymer coatings by spraying, the coating needs to have a low viscosity for easy spraying and to facilitate leveling on the horizontal surface, resulting in a better appearance. However, lower viscosity means that sagging is more likely to occur on vertical surfaces. To avoid sagging, the coating needs to have a higher viscosity, reducing its flowability. This requires striking a balance between leveling and sagging. The coating must maintain a certain leveling property under the high shear forces during spraying, while also returning to a high viscosity after spraying to prevent sagging once the high shear forces are removed. For baked coatings, in addition to the anti-sagging requirements during room temperature spraying, the coating also needs to prevent sagging during the heat curing process. More specifically, the coating after spraying needs to be heated and baked to cure. During the baking process before the curing reaction, the viscosity of the polymer decreases as the temperature increases. Therefore, the coating is more prone to sagging under baking conditions. For this reason, it is one of the technical requirements in the field of baking coatings to invent an additive with anti-sagging properties in the entire temperature range from room temperature to high temperature.

[0003] Allnex's SCA resin is formed by reacting HDI with benzylamine in a matrix resin to create polyurea crystals. There are no chemical bonds between the matrix resin and the SCA polyurea crystals; it's merely a physical mixture. Changchun University of Technology, in its application number 202010150786.0, used aliphatic TMXDI as the isocyanate portion. The prepolymer synthesized with hydroxyl polymers has lower viscosity and, being an aliphatic isocyanate, offers advantages such as resistance to aging and yellowing. However, none of these patents consider the practical application process of baking coatings, which requires room temperature spraying followed by high-temperature baking, and they do not include anti-sagging additives for the baking process.

[0004] In summary, there is an urgent need in this field to develop new anti-sagging agents with a wide temperature range and low environmental pollution, as well as their preparation methods. Summary of the Invention

[0005] The purpose of this invention is to provide a wide-temperature-range, low-environmental-pollution anti-sagging agent and its preparation method.

[0006] In a first aspect, the present invention provides a method for preparing an anti-sagging agent, comprising the following steps:

[0007] (a) The carrier resin, solvent, and fumed silica are mixed and dispersed to a fineness of <20 micrometers to obtain fumed silica modified resin;

[0008] (b) The fumed silica modified resin is mixed with amine substances, and isocyanate compounds are added and dispersed evenly to obtain the anti-sagging additive.

[0009] In another preferred embodiment, the carrier resin is a solvent-based resin, preferably selected from the group consisting of acrylic resin, amino resin, polyester resin, polyurethane resin, polyether resin, or a combination thereof.

[0010] In another preferred embodiment, the solvent-based resin is selected from acrylic resins, amino resins, or combinations thereof.

[0011] In another preferred embodiment, the viscosity of the solvent-based resin is 1000-3500 mPa·s.

[0012] In another preferred embodiment, the amount of fumed silica used is 0.1%-12% (mass fraction) based on the total weight of the fumed silica-modified resin.

[0013] In another preferred embodiment, the amount of fumed silica used is 0.5%-3% (mass fraction) based on the total weight of the fumed silica-modified resin.

[0014] In another preferred embodiment, the fumed silica is hydrophobic fumed silica.

[0015] In another preferred embodiment, the amine is selected from the group consisting of benzylamine, alpha-methylbenzylamine, alpha-ethylbenzylamine, p-methylbenzylamine, m-methylbenzylamine, o-methylbenzylamine, 3-(2-methoxyethyl)benzylamine, or combinations thereof.

[0016] In another preferred embodiment, the amount of the amine substance used is 1-6% (mass fraction) based on the total weight of the fumed silica-modified resin.

[0017] In another preferred embodiment, the amount of the amine substance used is 2-4% (mass fraction) based on the total weight of the fumed silica-modified resin.

[0018] In another preferred embodiment, the isocyanate compound is selected from the group consisting of hexamethylene diisocyanate, pentamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, tetramethyl-m-phenylenedimethyl diisocyanate, or combinations thereof.

[0019] In another preferred embodiment, the amount of the isocyanate compound used is 1-6% (mass fraction).

[0020] In another preferred embodiment, the amount of the isocyanate compound used is 2-4% (mass fraction).

[0021] In another preferred embodiment, the solvent is selected from the group consisting of naphtha, heptane, n-butanol, butyl acetate, xylene, aromatic hydrocarbon 100, methyl isopentyl ketone, methyl isobutyl ketone, methyl n-pentyl ketone, or combinations thereof.

[0022] In another preferred embodiment, the solvent is aromatic hydrocarbon 100, butyl acetate, or a combination thereof.

[0023] In another preferred embodiment, the anti-sagging agent is a pale blue to milky white paste-like liquid.

[0024] In another preferred embodiment, the anti-sagging agent contains 56-72 wt% solids.

[0025] In another preferred embodiment, the anti-sagging agent is measured at 300 s using an Anton Paar viscometer. -1 The viscosity at which the shear rate was tested was between 100 and 800 mPa·s.

[0026] In another preferred embodiment, the anti-sagging agent is measured using an Anton Pareto viscometer at 3S. -1 The viscosity with a shear rate is between 18,000 and 130,000 mPa·s.

[0027] In another preferred embodiment, the following steps are included:

[0028] (a) The carrier resin, solvent, and fumed silica are mixed and dispersed to a fineness of <20 micrometers to obtain fumed silica modified resin;

[0029] (b) The fumed silica modified resin is mixed with amine substances, and isocyanate compounds are added and dispersed evenly to obtain the anti-sagging additive.

[0030] In another preferred embodiment, in step (a), the dispersion includes: initial dispersion at 200-400 RPM, followed by further dispersion at 1000-3000 RPM to a fineness of <20 micrometers.

[0031] In another preferred embodiment, step (b) includes mixing: initial mixing at 200-400 RPM followed by further mixing at 1000-2000 RPM.

[0032] In another preferred embodiment, in step (b), the dispersion includes: stirring for 10-30 minutes, adding solvent and continuing to stir for 0.5-2 hours to obtain the anti-sagging agent.

[0033] In a second aspect, the present invention provides an anti-sagging agent, which is prepared by the method described in the first aspect of the present invention.

[0034] It should be understood that, within the scope of this invention, the above-described technical features of this invention and the technical features specifically described below (such as in the embodiments) can be combined with each other to form new or preferred technical solutions. Due to space limitations, they will not be described in detail here. Attached Figure Description

[0035] Figure 1 This is a scanning electron microscope image of the anti-sagging agent prepared in Example 2.

[0036] Figure 2 This is the temperature-rheological curve of the prepared anti-sagging agent. Detailed Implementation

[0037] Through extensive and in-depth research, the inventors have developed a novel anti-sagging agent and its preparation method for the first time. This invention involves mixing a carrier resin, a solvent, and fumed silica to obtain a fumed silica-modified resin, which is then mixed with amines and isocyanates to prepare an anti-sagging agent with a wide temperature range and low environmental pollution. This invention is based on this process.

[0038] Preparation method

[0039] (a) Preparation of fumed silica modified resin. The carrier resin, solvent and fumed silica are mixed and dispersed to a fineness of <20 micrometers to obtain fumed silica modified resin.

[0040] (b) Preparation of polyurea and fumed silica co-modified resin. The fumed silica modified resin is mixed with an amine substance, stirred at low speed until homogeneous, and then an isocyanate compound is added and quickly dispersed until homogeneous. The mixture is stirred to obtain the polyurea and fumed silica co-modified resin.

[0041] The main advantages of this invention include:

[0042] (1) The anti-sagging additive of the present invention can effectively solve the sagging problem during high-temperature baking, and is particularly suitable for solving the sagging problem of high-solids coatings.

[0043] (2) The anti-sagging additive of the present invention has a wide temperature range.

[0044] (3) The anti-sagging additive of the present invention has low environmental pollution and high economic benefits.

[0045] (4) The preparation method of the present invention is simple.

[0046] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. Percentages and parts are by weight unless otherwise stated.

[0047] Laboratory equipment, ETERAC 7307-2-PM-70 acrylic resin, fumed silica, and other common reagents are all commercially available.

[0048] Example 1. Preparation of fumed silica-modified acrylic resin

[0049] 20g of aromatic hydrocarbon 100, 36g of acrylic resin ETERAC 7307-2-PM-70, 9g of fumed silica, and 20g of butyl acetate were sequentially placed in a container and dispersed using a high-speed disperser (HSD) at a low speed of 300 RPM for 10 minutes, then the speed was increased to 2000 RPM and dispersed for 30 minutes. During the dispersion process, the temperature was controlled below 70℃. The fineness was checked. If it was less than 20 micrometers, the process was complete. If it was greater than 20 micrometers, the process was repeated for another 30 minutes until the fineness reached the standard of less than 20 micrometers, thus preparing the fumed silica-modified acrylic resin.

[0050] Example 2. Preparation of polyurea and fumed silica co-modified resin

[0051] 70g of the modified acrylic resin prepared in Example 1 and 1.85g of benzylamine were added to a container and stirred at a low speed of 300 RPM until homogeneous. The speed of the high-speed disperser (HSD) was increased to 1600 RPM, and 1.43g of hexamethylene diisocyanate (HDI) was added. The mixture was stirred for 20 minutes, and then 27g of aromatic hydrocarbon 100 was added and stirred for 60 minutes to obtain the polyurea and fumed silica co-modified resin (e.g., Figure 1 ).

[0052] The prepared anti-sagging agent was characterized using scanning electron microscopy. The image shows both needle-like crystal structures formed by polyurea and spherical structures formed by fumed silica, indicating that a resin modified by both polyurea and fumed silica was successfully prepared.

[0053] Using an Anton Paar viscometer, the viscosity was 539 mPa·s at a shear rate of 300 s⁻¹ and 43900 mPa·s at a shear rate of 3 s⁻¹. Using an Anton Paar temperature-modified rheometer, the upper temperature limit for viscosity above 20000 mPa·s reached 112 °C. Experimental results show that the prepared polyurea and fumed silica co-modified resin exhibits low viscosity at high shear rates and high viscosity at low shear rates. The prepared polyurea and fumed silica co-modified resin possesses high viscosity suitable for use as an anti-sagging agent, and the corresponding temperature range is relatively wide.

[0054] Example 3. Preparation of polyurea and fumed silica co-modified resin

[0055] 70g of the modified acrylic resin prepared in Example 1 and 2.1g of Alpha-ethylbenzylamine were added to a container and stirred at low speed until homogeneous. The HSD speed was increased to 1600 RPM, 1.34g of pentamethylene diisocyanate (PDI) was added, and the mixture was stirred for 20 minutes. Then, 27g of aromatic hydrocarbon 100 was added and stirred for 60 minutes to obtain the polyurea and fumed silica co-modified resin.

[0056] Using an Anton Paar viscometer, the viscosity was 739 mPa·s at a shear rate of 300 s⁻¹ and 57446 mPa·s at a shear rate of 3 s⁻¹. Using an Anton Paar temperature-modified rheometer, the upper temperature limit for achieving a viscosity above 20000 mPa·s was approximately 120 °C. Experimental results show that the prepared polyurea and fumed silica co-modified resin exhibits low viscosity at high shear rates and high viscosity at low shear rates. The prepared polyurea and fumed silica co-modified resin possesses high viscosity suitable for use as an anti-sagging agent, and the corresponding temperature range is relatively wide.

[0057] analyze

[0058] Since fumed silica can improve sag, this invention first prepares fumed silica-modified acrylic resin. This is because a uniform three-dimensional network structure (hydrogen bonds) is easily formed in a liquid system. This three-dimensional network structure (hydrogen bonds) is disrupted by external forces (shear force, electric field force, etc.), the medium becomes thinner, and the viscosity decreases. However, once the external force disappears, the three-dimensional structure (hydrogen bonds) recovers on its own, and the viscosity increases; that is, this thixotropy is reversible.

[0059] The preparation method of this invention first involves mixing a carrier resin, solvent, and fumed silica in a certain proportion, controlling the temperature at 15-70℃, and after the fineness of the mixture reaches below 20 micrometers, adding an amine substance and stirring until homogeneous. Then, an isocyanate substance is added and rapidly dispersed uniformly to obtain a paste-like anti-sagging agent. The mechanism for preparing the anti-sagging agent is shown in the figure below. That is, the preparation method of this invention is not a simple physical mixing, but rather a chemical synthesis of polyurea in a fumed silica slurry carrier.

[0060]

[0061] The anti-sagging agent prepared by the method of this invention is a light blue to milky white paste-like liquid with a solid content of 56-72%. The viscosity measured by an Anton Paar viscometer at a shear rate of 300 s⁻¹ is between 100-800 mPa·s, and at a shear rate of 3 s⁻¹, it is between 18000-130000 mPa·s. When tested using an Anton Paar temperature-rheometer, the upper temperature limit for a viscosity above 20000 mPa·s reaches approximately 120°C.

[0062] Figure 2 The diagram shows the temperature-rheological curves of the anti-sagging agents prepared in Examples 1, 2, and 3. The polyurea and fumed silica co-modified resins corresponding to Examples 2 and 3 exhibit high viscosity in the range of 40°C to 120°C and have a wide temperature range, indicating that the anti-sagging agent of the present invention has anti-sagging properties in both low and high temperature regions, and is particularly suitable for baking materials.

[0063] All documents mentioned in this invention are incorporated herein by reference as if each document were individually incorporated by reference. Furthermore, it should be understood that after reading the foregoing teachings of this invention, those skilled in the art can make various alterations or modifications to this invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A method for preparing an anti-sagging agent, characterized in that, Includes the following steps: (a) The carrier resin, solvent, and fumed silica are mixed and dispersed to a fineness of <20 micrometers to obtain fumed silica modified resin; (b) The fumed silica modified resin is mixed with amine substances, and isocyanate compounds are added and dispersed evenly to obtain the anti-sagging additive; Based on the total weight of the fumed silica-modified resin, the amines have a mass fraction of 1-6%, the isocyanates have a mass fraction of 1-6%, and the fumed silica has a mass fraction of 0.1%-12%. The carrier resin is a solvent-based resin, which is selected from the group consisting of: acrylic resin, amino resin, polyester resin, polyurethane resin, polyether resin, or a combination thereof; In step (b), the dispersion includes: stirring for 10-30 minutes, adding solvent and continuing to stir for 0.5-2 hours to obtain the anti-sagging agent, wherein the solvent is selected from the group consisting of naphtha, heptane, n-butanol, butyl acetate, xylene, aromatic 100, methyl isopentyl ketone, methyl isobutyl ketone, methyl n-pentyl ketone, or combinations thereof.

2. The preparation method according to claim 1, characterized in that, The amines are selected from the group consisting of benzylamine, Alpha-methylbenzylamine, Alpha-ethylbenzylamine, p-methylbenzylamine, m-methylbenzylamine, o-methylbenzylamine, 3-(2-methoxyethyl)benzylamine, or combinations thereof.

3. The preparation method according to claim 1, characterized in that, The isocyanate compounds are selected from the group consisting of hexamethylene diisocyanate, pentamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, tetramethyl-m-phenylenedimethyl diisocyanate, or combinations thereof.

4. The preparation method as described in claim 1, characterized in that, In step (a), the dispersion includes: initial dispersion at 200-400 RPM, followed by further dispersion at 1000-3000 RPM to a fineness of <20 micrometers.

5. The preparation method as described in claim 1, characterized in that, In step (b), the mixing includes: initial mixing at 200-400 RPM, followed by further mixing at 1000-2000 RPM.

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