A polyurethane modified black paste and its preparation process

Abstract

The invention discloses a polyurethane modified special black paste and a preparation process thereof. The polyurethane modified special black paste comprises: 20-40 parts by weight of polyurethane, 5-15 parts by weight of black pulp, 20-40 parts by weight of auxiliary agent and 20-40 parts by weight of solvent; the auxiliary agent comprises 5-10 parts by weight of dispersant, 5-10 parts by weight of defoamer, 5-10 parts by weight of leveling agent and 5-10 parts by weight of lubricant; the dispersant is a modified polystyrene-maleic acid dispersant, and the modified dispersant enhances the dispersibility and stability of the color paste through physical and chemical effects, and has broad application prospects.

Description

Technical Field

[0001] The invention relates to the field of pigment preparation, in particular to a polyurethane modified special black paste and a preparation process thereof. Background Art

[0002] Color paste, also known as color slurry, is a semi-finished product made by dispersing pigments or pigments and fillers in paint. Oil-based color paste uses pure oil as an adhesive, resin paint uses resin paint as an adhesive, and water-based color paste uses water as a medium to add surfactants to disperse the pigment and filler. Since there are many types of paints, there are also many types of color pastes. In order to better disperse pigments in paints, a small amount of surfactants, zinc cyclohexaneate, etc. are often added during the manufacturing process.

[0003] However, water-based colorants still have defects in stability and dispersibility, which need to be further improved. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a preparation process of a polyurethane modified special black paste. The color paste is prepared by the method of the present invention, and the prepared color paste has good dispersibility and strong stability.

[0005] The technical solution of the present invention is achieved in this way:

[0006] The present invention provides a polyurethane modified special black paste, the components of which are: 20-40 parts by weight of polyurethane, 5-15 parts by weight of black paste, 20-40 parts by weight of auxiliary agent and 20-40 parts by weight of solvent.

[0007] Water-based color pastes are usually composed of water-based binders, pigments and various additives. The water-based binder disperses the pigment evenly. The performance of the water-based binder affects the rheology, water resistance and adhesion of the color paste to the substrate. The resins used as water-based binders mainly include water-based acrylic resins, polyvinyl alcohol and water-based polyurethane (WPU). Among them, WPU has the characteristics of strong structural designability, easy use, safety and environmental protection.

[0008] Furthermore, the polyurethane is a polyether type water-based polyurethane.

[0009] Furthermore, the preparation method of the polyether type waterborne polyurethane is as follows: polycarbonate diol and diisocyanate are mixed and heated to perform a prepolymerization reaction, a catalyst is added to continue the reaction, a hydrophilic chain extender and triethylamine are added after cooling and the temperature is raised to continue the reaction, after the reaction is completed, the temperature is lowered and triethylamine and a neutralizing agent are added to perform a neutralization reaction, and the reaction product is dispersed in deionized water to obtain the polyether type waterborne polyurethane.

[0010] The raw materials for preparing waterborne polyurethane are relatively abundant, and different types of raw materials can give polyurethane different properties. According to the different types of soft segment raw materials for synthesizing WPU, WPU binders can be divided into polyether type and polyester type. At present, the soft segments used in the reported polyether type WPU binders include polytetramethylene glycol, polypropylene glycol, etc. Polyether type WPU has the characteristics of good flexibility and good water resistance.

[0011] Furthermore, the polycarbonate diol is polypropylene carbonate diol.

[0012] Polypropylene carbonate diol (PPCD) is an environmentally friendly oligomer diol produced by copolymerization of propylene oxide and greenhouse gas carbon dioxide.

[0013] Furthermore, the catalyst is an environmentally friendly catalyst BiCAT8108.

[0014] Furthermore, the chain extender is a hydrophilic chain extender 2,2-dimethylolpropionic acid (DMPA).

[0015] The introduction of hydrophilic chain extenders can enhance the dispersibility and stability of water-based color pastes.

[0016] Furthermore, the auxiliary agent includes 5-10 parts by mass of a dispersant, 5-10 parts by mass of a defoamer, 5-10 parts by mass of a leveling agent, and 5-10 parts by mass of a lubricant.

[0017] Furthermore, the dispersant is a modified polystyrene-maleic acid dispersant.

[0018] In order to improve the dispersibility of the color paste in water, the pigment itself can be surface modified or surfactants can be used. The use of polymer dispersants to disperse the color paste can greatly improve the dispersion stability, and has the advantages of low volatility, low cost and simple process. At present, the most widely used polymer dispersant is a carboxyl functional group polymer, which is usually polymerized with maleic anhydride, acrylic acid or methacrylic acid main chain. In recent years, people have been using styrene-maleic acid dispersants more and more widely. Its dispersion mechanism lies in its special structure. One part is converted by acid anhydride and benzene ring under certain conditions by hydrolysis, sulfonation, amidation, etc. to carboxyl, carboxylate, sulfonic acid, sulfonate, polyamine, etc. to provide anchoring groups; the other part is provided by non-polar benzene rings and polymer chain lengths to provide steric hindrance effects. Under the dual effect, ultrafine particles are wetted and dispersed without flocculation.

[0019] Furthermore, the preparation method of the modified polystyrene-maleic acid dispersant is as follows: tung oil and methanol are mixed, catalyst 1 is added, and heating reaction is performed to obtain tung oil methyl ester; tung oil methyl ester and 1,4-butanediol are mixed, catalyst 2 is added, and heating reaction is performed to obtain tung oil alcohol; ethyl acetate and polystyrene-maleic anhydride are mixed, tung oil alcohol, methoxy polyethylene glycol and catalyst 3 are added, and heating reaction is performed to obtain the modified polystyrene-maleic acid dispersant.

[0020] Tung oil-based alcohol is a renewable, multifunctional green material that not only contributes to hydrophobicity, but also provides copolymerization points for ester bonds and unsaturated double bonds; the methoxy polyethylene glycol (MPEG) chain segment can enhance the hydrophilicity of the dispersant and provide a steric hindrance effect.

[0021] Furthermore, the defoaming agent is silicone oil.

[0022] Silicone oil has high heat resistance, water resistance, electrical insulation and low surface tension.

[0023] Furthermore, the leveling agent is talcum powder.

[0024] Talc powder with fibrous particle structure can greatly improve the rheological properties and leveling properties of the coating, and at the same time improve the weather resistance of the coating.

[0025] Furthermore, the lubricant is diethanolamine.

[0026] The present invention also provides a preparation process of a polyurethane modified extra black paste, the preparation method comprising: mixing 20-40 parts by mass of polyurethane, 5-15 parts by mass of black pulp, 20-40 parts by mass of an auxiliary agent and 20-40 parts by mass of a solvent and dispersing the mixture evenly to obtain the polyurethane modified extra black paste.

[0027] Compared with the prior art, the present invention has the following beneficial effects: tung oil-based alcohol is a renewable, multifunctional green material, which not only contributes to hydrophobicity but also provides copolymerization points of ester bonds and unsaturated double bonds; the methoxy polyethylene glycol (MPEG) chain segment can enhance the hydrophilicity of the dispersant and provide a steric hindrance effect. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described in combination with the embodiments below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Reagent Description:

[0030] Polypropylene carbonate diol, diphenylmethane diisocyanate, 2,2-dihydroxymethylpropionic acid, triethylamine, potassium hydroxide, 1,4-butanediol, p-toluenesulfonic acid, ethyl acetate, polystyrene-maleic anhydride, methoxypolyethylene glycol, silicone oil, talc, diethanolamine, analytical grade, Sinopharm Chemical Reagent Co., Ltd.; BiCAT8108, analytical grade, Leading Chemical Company, USA; tung oil, industrial grade, Tongyuan Oil Industry Co., Ltd., Xingyi City, Guizhou Province.

[0031] Preparation Example 1

[0032] Preparation of polyether type waterborne polyurethane: 250g polypropylene carbonate diol and 750g diphenylmethane diisocyanate are loaded into a reactor, stirred for 20min, heated to 90°C for prepolymerization, 1g environmentally friendly catalyst BiCAT8108 is added after 1.5h, the reaction is continued for 4h, the temperature is lowered to 60°C, 30g hydrophilic chain extender 2,2-dimethylol propionic acid and 1L triethylamine are added, the temperature is raised to 80°C for reaction for 6h, the temperature is lowered to 50°C, triethylamine is added to adjust the viscosity to 1500-2500cP, triethylamine is added in an amount equimolar to 2,2-dimethylol propionic acid, and neutralization reaction is carried out for 30min; the reactants are poured into a dispersion bottle, placed in a 3000r / min disperser, slowly added into 10°C deionized water for emulsification and dispersion, and triethylamine is removed at 55°C and -0.095MPa to obtain the polyether type waterborne polyurethane.

[0033] Preparation Example 2

[0034] Preparation of modified polystyrene-maleic acid dispersant: 100g of tung oil and 900g of methanol are loaded into a reactor, 1g of catalyst 1 potassium hydroxide is added, and the mixture is reacted at 80°C for 90min, and tung oil-based methyl ester is obtained after separation and purification; 100g of the tung oil-based methyl ester and 150g of 1,4-butanediol are loaded into a reactor, 1g of catalyst 2 p-toluenesulfonic acid is added, the mixture is reacted at 120°C for 3h, and tung oil-based alcohol is obtained after separation and purification; 100g of polystyrene-maleic anhydride is added to 200g of ethyl acetate under a nitrogen atmosphere, the mixture is heated to 60°C to dissolve and stirred evenly, and 100g of the tung oil-based alcohol, 150g of methoxy polyethylene glycol, and 1.5g of catalyst 3 p-toluenesulfonic acid are added.

[0035] Example 1

[0036] 30g of the polyether waterborne polyurethane, 10g of black slurry, 10g of the modified polystyrene-maleic acid dispersant, 10g of silicone oil, 10g of talcum powder, 10g of diethanolamine, and 30g of deionized water were mixed and dispersed at high speed for 20min, and then transferred to a grinder for grinding and dispersion for 1h at a speed of 2000r / min to obtain the polyurethane modified extra black paste.

[0037] Example 2

[0038] The difference between this embodiment and embodiment 1 is that the added amount of the modified polystyrene-maleic acid dispersant is 2 g.

[0039] The other parts are exactly the same as those in Example 1.

[0040] Example 3

[0041] The difference between this embodiment and embodiment 1 is that the added amount of the modified polystyrene-maleic acid-based dispersant is 4 g.

[0042] The other parts are exactly the same as those in Example 1.

[0043] Example 4

[0044] The difference between this embodiment and embodiment 1 is that the added amount of the modified polystyrene-maleic acid dispersant is 6 g.

[0045] The other parts are exactly the same as those in Example 1.

[0046] Example 5

[0047] The difference between this embodiment and embodiment 1 is that the added amount of the modified polystyrene-maleic acid-based dispersant is 8 g.

[0048] The other parts are exactly the same as those in Example 1.

[0049] Comparative Example 1

[0050] The difference between this comparative example and Example 1 is that the added amount of the modified polystyrene-maleic acid-based dispersant is 0 g.

[0051] The other parts are exactly the same as those in Example 1.

[0052] Tests and Results

[0053] The viscosity of the prepared polyurethane modified special black paste was measured, and the results are shown in Table 1.

[0054] Table 1

[0055] project <![CDATA[Viscosity (mPa·s -1 )]]> Example 1 17.3 Example 2 8.0 Example 3 9.5 Example 4 10.5 Example 5 14.0 Comparative Example 1 7.0

[0056] As can be seen from Table 1, the increase in the amount of dispersant increases the proportion of high molecular weight polymers in the system, and the macromolecules are more likely to entangle with each other to form molecular micelles, which promotes the dispersion of the color paste; secondly, after the tung oil is modified, the branching in the SMA main chain increases and with the increase in the amount of grafted tung oil-based alcohol, the number of branches of the dispersant is expanded and the relative molecular weight is increased, and the viscosity of the tung oil raw material itself is relatively high. Therefore, the addition amount of dispersant is more appropriate to be 6g.

[0057] The polyurethane modified special black paste prepared in Example 4 and Comparative Example 1 was placed at 5°C, 15°C, 25°C, 35°C, 45°C, 55°C and 65°C for 7 days, and its stability was tested. The results are shown in Table 2.

[0058] Table 2

[0059]

[0060] As can be seen from Table 2, when stored at 5°C, 45°C, 55°C, and 65°C, the low temperature stability and thermal stability of Example 4 are greater than those of Comparative Example 1, and after storage at 55°C, the thermal stability decreases slowly compared to 45°C. This is mainly because the dispersant adsorbs carbon black through the van der Waals force formed by the anchoring group, the π-π bond between molecules, the hydrogen bond, etc. When the temperature rises, the Brownian motion between particles will be enhanced. If the adsorption force is not enough to hinder the attraction between particles, the particle size of the color paste particles will increase and the storage stability will decrease; as the temperature rises, water molecules continue to escape, and the hydrophobic end and the hydrophilic end on the side chain of the dispersant appear to be close to each other, so that the color paste particles are constantly in contact. Tung oil has the effect of hindering the escape of water molecules to a certain extent, thereby slowing down the close phenomenon; in addition, electrostatic repulsion and adsorption layer thickness are also the main factors affecting the stability of the dispersion. The dispersant modified by tung oil enhances the adsorption layer thickness of the dispersion. Under the same electrostatic repulsion, the thicker the adsorption layer thickness, the better the stability.

[0061] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A polyurethane modified black paste, characterized in that: The composition is: 20-40 parts by weight of polyurethane, 5-15 parts by weight of black paste, 20-40 parts by weight of additives, and 20-40 parts by weight of solvents; The auxiliary agent includes 5-10 parts by mass of dispersant, 5-10 parts by mass of defoamer, 5-10 parts by mass of leveling agent and 5-10 parts by mass of lubricant; The dispersant is a modified polystyrene-maleic acid dispersant; The preparation method of the modified polystyrene-maleic acid dispersant is as follows: tung oil and methanol are mixed, catalyst 1 is added, and heating reaction is performed to obtain tung oil methyl ester; tung oil methyl ester and 1,4-butanediol are mixed, catalyst 2 is added, and heating reaction is performed to obtain tung oil alcohol; ethyl acetate and polystyrene-maleic anhydride are mixed, tung oil alcohol, methoxy polyethylene glycol and catalyst 3 are added, and heating reaction is performed to obtain the modified polystyrene-maleic acid dispersant.

2. A polyurethane modified black paste according to claim 1, characterized in that: The polyurethane is a polyether type waterborne polyurethane.

3. A polyurethane modified black paste according to claim 2, characterized in that: The preparation method of the polyether type waterborne polyurethane comprises the following steps: mixing polycarbonate diol and diisocyanate and heating them to perform a prepolymerization reaction, then adding a catalyst to continue the reaction, cooling down and adding a hydrophilic chain extender and triethylamine and heating up to continue the reaction, cooling down after the reaction and adding triethylamine and a neutralizing agent to perform a neutralization reaction, and dispersing the reaction product in deionized water to obtain the polyether type waterborne polyurethane.

4. A polyurethane modified black paste according to claim 1, characterized in that: The defoaming agent is silicone oil.

5. The polyurethane modified black paste according to claim 1, characterized in that: The leveling agent is talcum powder.

6. The polyurethane modified black paste according to claim 1, characterized in that: The lubricant is diethanolamine.

7. A process for preparing a polyurethane modified black paste, characterized in that: The components of claim 1 are mixed and dispersed uniformly at high speed to obtain the polyurethane modified special black paste.

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