Preparation method and application of polycarboxylic acid dispersing agent

Abstract

The invention relates to the technical field of polycarboxylic acid dispersing agents, and discloses a preparation method and application of a polycarboxylic acid dispersing agent, hydroxyl in 3, 5-dihydroxy methyl benzoate and epoxypropane are subjected to ring opening polymerization under the catalysis of boron trifluoride diethyl ether to obtain a polyether intermediate 1, the polyether intermediate 1 is placed in a sodium hydroxide solution for a reaction, and the polycarboxylic acid dispersing agent is obtained. The allyl carboxyl polyether is obtained. Allyl carboxyl polyether, sodium 4-vinyl benzene sulfonate and hydroxyethyl acrylate are subjected to initiation copolymerization under the action of ammonium persulfate to obtain the polycarboxylic acid dispersing agent. Finally, adding talcum powder, a polycarboxylic acid dispersing agent, a defoaming agent, a flatting agent and a coalescing agent into the styrene-acrylic solution, and uniformly stirring to obtain the styrene-acrylic coating. The polycarboxylic acid dispersing agent prepared by the preparation method disclosed by the invention is applied to a coating, and can play a better dispersing role on the coating and enhance the stability of the coating.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of polycarboxylic acid dispersants, in particular to a preparation method of a polycarboxylic acid dispersant and application thereof. BACKGROUND

[0002] Corrosion of metal is a phenomenon that metal is destroyed due to chemical or electrochemical action of environmental medium, and has spread in various fields of the national economy, causing huge economic losses, so people use various technologies to protect the metal and prevent corrosion from occurring. The most effective and most commonly used method for metal corrosion protection is to coat a coating on the surface of the metal to isolate the matrix from the metal matrix.

[0003] The styrene-acrylic coating is prepared from styrene and acrylic acid (ester) copolymer emulsion, has good weather resistance, water resistance, alkali resistance and other properties, has the advantages of being non-toxic, odorless, non-flammable and non-explosive, and strong adhesion with pigments, and is widely applied in fields such as building coatings, floor coatings, metal emulsion coatings, paper adhesives and inks. However, the stability of the coating will decrease due to long-term storage, so it is very important to add a dispersant to the coating to increase the storage time of the coating.

[0004] The dispersant is a kind of surface active agent, which can anchor and isolate the solid particle surface, so that it is stably suspended in the slurry system, and can prevent the particles from re-aggregating under long-term storage conditions, thereby improving the stability of the coating. At present, water-based high molecular dispersants are widely concerned and researched due to their environmental protection and safety, among which water-based high molecular polyether and polycarboxylate are common dispersants and are widely applied in fields such as coatings, mortar, medicine, water treatment and the like. SUMMARY

[0005] The technical problem solved by the application is to provide a preparation method of a polycarboxylic acid dispersant and application thereof. The polycarboxylic acid dispersant prepared by the application is applied to the coating, and the problem of stability decrease of the coating in long-term storage is solved.

[0006] The technical scheme of the application is: A preparation method of a polycarboxylic acid dispersant, wherein the preparation method is as follows: In a nitrogen atmosphere, allyl carboxyl polyether, 4-vinylbenzenesulfonic acid sodium and hydroxyethyl acrylate are dissolved in a reaction kettle containing deionized water, then ammonium persulfate is added, the temperature is controlled at 70-80 DEG C, and the reaction is carried out for 2-4 hours. After the reaction is completed, the temperature is cooled to 35-45 DEG C, ammonia water is used to adjust the pH to 6.5-7.5, the temperature is cooled to room temperature, and the polycarboxylic acid dispersant is obtained by vacuum concentration.

[0007] Preferably, in the step, the mass ratio of allyl carboxyl polyether, sodium 4-vinylbenzenesulfonate, hydroxyethyl acrylate and ammonium persulfate is 1:0.2-0.4:0.5-1:0.018-0.024.

[0008] Preferably, in the step, the preparation method of the allyl carboxyl polyether is: (1) In a nitrogen atmosphere, methyl 3,5-dihydroxybenzoate, boron trifluoride ether, propylene oxide are added to the reaction kettle, and the reaction is carried out under heating, after the reaction is completed, it is cooled to room temperature, and concentrated under reduced pressure to obtain polyether intermediate 1.

[0009] (2) At 85-100℃, sodium hydroxide solution is added to the flask containing polyether intermediate 1, and the reaction is carried out for 40-80min, and when the pH is controlled at 8-10, the reaction is completed, and then it is washed with diethyl ether and dried to obtain allyl carboxyl polyether.

[0010] Preferably, in the step (1), the molar ratio of methyl 3,5-dihydroxybenzoate, boron trifluoride ether and propylene oxide is 1:1.8-2.2:18-24.

[0011] Preferably, in the step (1), the heating reaction time is 2-4h, and the temperature is 120-150℃.

[0012] Preferably, in the step (2), the concentration of sodium hydroxide solution is 10-18%.

[0013] Preferably, talc, polycarboxylic acid dispersant are added to the styrene-acrylate solution, stirred and dispersed, defoaming agent, leveling agent, film forming aid are added, and stirred uniformly to obtain styrene-acrylate paint.

[0014] Preferably, in the step, the mass ratio of polycarboxylic acid dispersant and styrene-acrylate solution is 0.03-0.06:1.

[0015] The beneficial technical effects of the present application are: The hydroxyl group in methyl 3,5-dihydroxybenzoate is ring-opening polymerized with propylene oxide under the catalysis of boron trifluoride ether to obtain polyether intermediate 1, which is then reacted in sodium hydroxide solution to obtain allyl carboxyl polyether. The allyl carboxyl polyether is copolymerized with sodium 4-vinylbenzenesulfonate and hydroxyethyl acrylate under the initiation of ammonium persulfate to obtain polycarboxylic acid dispersant. Finally, talc, polycarboxylic acid dispersant, defoaming agent, leveling agent and film forming aid are added to the styrene-acrylate solution, and stirred uniformly to obtain styrene-acrylate paint.

[0016] The polycarboxylic acid dispersant prepared by the method has carboxylic acid groups, sulfonic acid groups and polyether structures, and the hydrophilic groups with carboxylic acid groups, sulfonic acid groups and polyether structures are located on the surface of the particles and face water after the polycarboxylic acid dispersant is dispersed in the coating, the hydrophobic monomers are wrapped in the inside of the particles to form the core of the particles, the particles themselves have charges, and the same amount of opposite charges are adsorbed around the particles to form a double-layer structure, an electromotive force is generated, and a strong electrostatic action is formed between the latex particles, thereby effectively preventing the agglomeration of the latex particles and increasing the stability of the coating. The polycarboxylic acid dispersant prepared by the method can play a good dispersing role on the coating and enhance the stability of the coating. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a preparation route of the allyl carboxyl polyether. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0019] Embodiment 1 (1) 4 mol of methyl 3,5-dihydroxybenzoate, 8 mol of boron trifluoride etherate and 90 mol of propylene oxide were added to a reaction kettle under a nitrogen atmosphere, the temperature was raised to 1400℃, and reaction was carried out for 4 h. After the reaction was completed, the temperature was cooled to room temperature, and vacuum concentration was carried out to obtain a polyether intermediate 1.

[0020] (2) A flask containing the polyether intermediate 1 was added with a sodium hydroxide solution with a concentration of 15% at 90℃, reaction was carried out for 60 min, and the reaction was completed when the pH was controlled to be 8. Ether washing and drying were carried out to obtain an allyl carboxyl polyether.

[0021] (3) 50 g of the allyl carboxyl polyether, 15 g of sodium 4-vinylbenzenesulfonate and 40 g of hydroxyethyl acrylate were dissolved in a reaction kettle containing deionized water under a nitrogen atmosphere, 1 g of ammonium persulfate was further added, the temperature was controlled to be 75℃, reaction was carried out for 4 h, and after the reaction was completed, the temperature was cooled to 40℃, ammonia water was used to adjust the pH to 7, the temperature was cooled to room temperature, and vacuum concentration was carried out to obtain a polycarboxylic acid dispersant.

[0022] (4) 40 g of talc powder and 6 g of the polycarboxylic acid dispersant were added to 200 g of a styrene-acrylic solution, stirring and dispersion were carried out, 1.5 g of a defoaming agent, 1.2 g of a leveling agent and 14 g of a film-forming aid were added, and stirring was uniformly carried out to obtain a styrene-acrylic coating.

[0023] Embodiment 2 The difference between this embodiment and embodiment 1 is that the amount of polycarboxylic acid dispersant in step (4) is 7g.

[0024] Example 3 The difference between this embodiment and embodiment 1 is that the amount of polycarboxylic acid dispersant in step (4) is 8g.

[0025] Example 4 The difference between this embodiment and embodiment 1 is that the amount of polycarboxylic acid dispersant in step (4) is 9g.

[0026] Example 5 The difference between this embodiment and embodiment 1 is that the amount of polycarboxylic acid dispersant in step (4) is 10g.

[0027] Example 6 The difference between this embodiment and embodiment 1 is that the amount of polycarboxylic acid dispersant in step (4) is 11g.

[0028] Example 7 The difference between this embodiment and embodiment 1 is that the amount of polycarboxylic acid dispersant in step (4) is 12g.

[0029] Comparative Example 1 The difference between this comparative example 1 and embodiment 1 is that allyl carboxyl polyether is used instead of polycarboxylic acid dispersant in step (4).

[0030] The paint was left to stand for 30 days to observe its storage stability and coating film appearance

[0031] As can be seen from the table, the paint stability of examples 1-7 is better than that of comparative example 1, because polycarboxylic acid dispersant is added in examples 1-7, which has good dispersion effect and can improve the stability of the paint. In comparative example 1, only allyl carboxyl polyether is added, which has a dispersion effect worse than that of examples 1-7. The dispersant prepared by the present application is applied to the styrene-acrylic emulsion, which has a good dispersion effect on the styrene-acrylic emulsion to enhance its stability.

[0032] The strength of emulsifying ability is judged according to the separation time of oil and water phases after emulsification.

[0033] The surface tension of the dispersant is tested by using a full-automatic surface tension meter.

[0034]

[0035] The longer the layered time, the better the emulsifying ability and the better the dispersibility. The greater the surface tension value, the stronger the hydrophilicity and the better the dispersibility. As shown in the table, the dispersant performance of Examples 1-7 is better than that of Comparative Example 1. This is because the poly carboxylic acid dispersant is used in Examples 1-7, while no poly carboxylic acid dispersant is used in Comparative Example 1, and the dispersing effect is poor.

[0036] The specific embodiments are only an explanation of the present application, and are not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the specification, as long as the modifications are within the scope of the claims of the present application.

Claims

1. A method for preparing a polycarboxylic acid dispersant, characterized in that, The preparation method is as follows: In a nitrogen atmosphere, allyl carboxylated polyether, sodium 4-vinylbenzenesulfonate, and hydroxyethyl acrylate are dissolved in a reactor containing deionized water. Ammonium persulfate is then added, and the temperature is controlled at 70-80℃. The reaction is carried out for 2-4 hours. After the reaction is completed, the mixture is cooled to 35-45℃, the pH is adjusted to 6.5-7.5 with ammonia, cooled to room temperature, and concentrated under reduced pressure to obtain a polycarboxylic acid dispersant.

2. The method for preparing the polycarboxylic acid dispersant according to claim 1, characterized in that, In the steps described, the mass ratio of allyl carboxylated polyether, sodium 4-vinylbenzenesulfonate, hydroxyethyl acrylate, and ammonium persulfate is 1:0.2-0.4:0.5-1:0.018-0.

024.

3. The method for preparing the polycarboxylate dispersant according to claim 1, characterized in that, In the aforementioned steps, the allyl carboxylated polyether is prepared as follows: (1) In a nitrogen atmosphere, methyl 3,5-dihydroxybenzoate, boron trifluoride diethyl ether and propylene oxide were added to a reaction vessel and heated to react. After the reaction was completed, the mixture was cooled to room temperature and concentrated under reduced pressure to obtain polyether intermediate 1. (2) At 85-100℃, sodium hydroxide solution was added to the flask containing polyether intermediate 1. The reaction was carried out for 40-80 min. When the pH was controlled at 8-10, the reaction was completed. The product was washed with ether and dried to obtain allyl carboxylated polyether.

4. The method for preparing the polycarboxylate dispersant according to claim 3, characterized in that, In step (1), the molar ratio of methyl 3,5-dihydroxybenzoate, boron trifluoride ether, and propylene oxide is 1:1.8-2.2:18-24.

5. The method for preparing the polycarboxylate dispersant according to claim 3, characterized in that, In step (1), the heating reaction time is 2-4 hours and the temperature is 120-150℃.

6. The method for preparing the polycarboxylate dispersant according to claim 3, characterized in that, In step (2), the concentration of the sodium hydroxide solution is 10-18%.

7. The application of the polycarboxylate dispersant obtained by the preparation method according to any one of claims 1-6 in styrene-acrylic coatings, characterized in that, Add talc and polycarboxylic acid dispersant to a styrene-acrylic solution, stir to disperse, add defoamer, leveling agent and film-forming aid, stir evenly to obtain styrene-acrylic coating.

8. The application of the polycarboxylate dispersant according to claim 7 in styrene-acrylic coatings, characterized in that, In the aforementioned steps, the mass ratio of polycarboxylic acid dispersant to styrene-acrylic solution is 0.03-0.06:1.

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