阅读说明：本技术 一种大粒径聚丙烯酸酯乳胶粒子的制备方法 (Preparation method of polyacrylate latex particles with large particle size ) 是由 潘明旺 李耀兴 袁金凤 张广林 潘志成 于 2021-09-07 设计创作，主要内容包括：本发明为一种大粒径聚丙烯酸酯乳胶粒子的制备方法。该方法包括以下步骤：(1)制备聚丙烯酸酯酯待附聚胶乳；(2)将甲基丙烯酸二甲氨基乙酯、去离子水和分子量调节剂混合反应,得到高分子附聚剂；(3)再将待附聚胶乳和高分子附聚剂混合反应,得到附聚后大粒径粒子胶乳。本发明可通过控制pH、附聚剂加入量和附聚剂浓度调控最终制备的大粒径乳胶粒的粒径和粒径分布。(The invention relates to a preparation method of polyacrylate emulsion particles with large particle size. The method comprises the following steps: (1) preparing a polyacrylate ester latex to be agglomerated; (2) mixing dimethylaminoethyl methacrylate, deionized water and a molecular weight regulator for reaction to obtain a polymer agglomerating agent; (3) then mixing the latex to be agglomerated and a high-molecular agglomerating agent for reaction to obtain the agglomerated latex with large-particle-size particles. The invention can regulate and control the particle size and the particle size distribution of the finally prepared large-particle-size latex particles by controlling the pH, the addition amount of the agglomerating agent and the concentration of the agglomerating agent.)

1. A preparation method of polyacrylate latex particles with large particle size is characterized by comprising the following steps:

(1) synthesis of the latex to be agglomerated

Adding a first emulsifier and first deionized water into a reactor, stirring for 10-30 minutes, then adding n-butyl acrylate and a crosslinking agent, continuing stirring for 10-30 minutes, heating under the conditions of nitrogen atmosphere and condensation reflux, adding a first initiator when the temperature is increased to 65-80 ℃, and carrying out heat preservation reaction for 1-3 hours; then, adding a second emulsifier and second deionized water, then dropwise adding the mixed monomer for 1-3 hours, dropwise adding a second initiator for 2-5 times in the dropwise adding process, and after dropwise adding, carrying out heat preservation reaction for 3-5 hours to obtain latex to be agglomerated;

the mixed monomer consists of n-butyl acrylate and glycidyl methacrylate, and the mass ratio of the n-butyl acrylate to the glycidyl methacrylate is 100-200: 10 to 50; the mass ratio of the materials is as follows:

(2) synthesis of an agglomerating agent

Adding dimethylaminoethyl methacrylate, third deionized water and a molecular weight regulator into another reactor, stirring for 30 minutes in a nitrogen atmosphere, heating, condensing and refluxing, adding a third initiator at 65-80 ℃, reacting for 3-5 hours in a heat preservation manner, and diluting by 2-10 times with water to obtain an agglomerating agent;

wherein the mass ratio of the dimethylaminoethyl methacrylate: third deionized water: molecular weight regulator: and (3) a third initiator is 2-10: 50-100: 0.02-0.1: 0.02 to 0.1;

(3) agglomeration step

Heating the latex to be agglomerated to 25-65 ℃, adjusting the pH value of the emulsion to 3-6, stirring at a low rotation speed for 10-60 minutes, adding the agglomerating agent prepared in the step (2) at a high rotation speed, and continuously stirring at a low rotation speed for 20-60 minutes to obtain the agglomerated latex with a large particle size;

wherein the mass ratio of the latex to be agglomerated is: 50-100% of an agglomerating agent: 2 to 20.

2. The method according to claim 1, wherein in step (1), the first emulsifier and the second emulsifier are both sodium dodecyl sulfate or sodium dodecyl benzene sulfonate.

3. The method for preparing large-particle-size polyacrylate latex particles according to claim 1, wherein in the step (1), the crosslinking agent is 1, 4-butanediol diacrylate or allyl methacrylate.

4. The method for preparing large-particle-size polyacrylate latex particles according to claim 1, wherein in the step (1) and the step (2), the first initiator, the second initiator or the third initiator is potassium persulfate or ammonium persulfate; the first initiator, the second initiator or the third initiator are added in the form of solution, and the concentration of the solution is 0.2-1.5 g of initiator per 20-60 g of solution.

5. The method for preparing large-particle size polyacrylate latex particles according to claim 1, wherein in step (2), the molecular weight regulator is tert-dodecyl mercaptan or dodecyl mercaptan.

6. The method for preparing large-particle-size polyacrylate emulsion particles according to claim 1, wherein the high rotation speed in step (3) is 100 to 300rpm, and the low rotation speed is 50 to 100 rpm.

Technical Field

The invention relates to a preparation method of polyacrylate latex particles with large particle size, in particular to a preparation technology of a specific agglomerating agent, the particle size of polyacrylate latex is regulated and controlled by the agglomerating agent, and the polyacrylate latex particles with large particle size prepared by the method can be used for producing high-performance ASA resin.

Background

The ASA resin is a ternary graft copolymer consisting of n-butyl acrylate-styrene-acrylonitrile, and the polybutadiene rubber in the ABS resin is replaced by the double-bond-free poly (n-butyl acrylate), so the ASA resin has high impact resistance, high mechanical strength, good weather resistance and chemical corrosion resistance, and is widely applied to the fields of electronic appliances, automobiles, building materials and the like. Like ABS, ASA resins are usually prepared by grafting a shell layer of a styrene (St) and Acrylonitrile (AN) copolymer plastic phase onto the inside of a rubber phase latex particle, and then blending with a certain proportion of SAN resin. The rubber phase particles required are larger in size to meet performance requirements. The existing method for synthesizing the latex particles with large particle size mainly comprises 2 methods, namely directly synthesizing the latex with large particle size in the polymerization process, which is called a one-step method; secondly, firstly synthesizing small-particle-size emulsion particles, and then agglomerating the small-particle-size emulsion particles into large-particle-size emulsion particles, which is called agglomeration method. The one-step method for directly synthesizing the latex particles with large particle sizes has the advantages of long production period, poor stability, complex operation and single particle size of the synthesized latex, and is gradually replaced by an agglomeration method at present.

CN110655599A discloses a weak acid in-situ agglomeration method, which is to add a weak acid in the polymerization process to reduce the stability of an emulsion system and realize the agglomeration of latex particles; CN102050998B utilizes butyl acrylate, methacrylic acid and styrene to prepare an agglomerant, and can prepare polybutadiene latex with super large particle size of 400-1000 nm; CN103897095A is prepared by adding a certain amount of acetic acid in the emulsion polymerization process, and the agglomeration of styrene-butadiene latex and polybutadiene latex can be realized. Most of the current chemical agglomeration methods and polymer latex agglomeration methods utilize copolymerization of monomers containing carboxylic acid groups and acrylate monomers to prepare an agglomerating agent, and the carboxylic acid groups reduce the stability of the emulsion system to achieve agglomeration.

The technical scheme of the invention aims to develop a novel agglomeration technology, which is different from the traditional polymer agglomeration method in that latex particles are used as an agglomerating agent, a high-molecular linear polymer is used as the agglomerating agent, agglomeration is realized through the physicochemical action of the agglomerating agent and the surfaces of the latex particles to be agglomerated, and the particle size of the latex particles can be effectively increased.

Disclosure of Invention

The invention aims to break the limitation of agglomeration by utilizing carboxylic acid groups at present and provide a preparation method of polyacrylate latex particles with large particle size. The method adopts a hydrophilic polymer chain as an agglomerating agent, and reduces the hydrophobicity of latex particles by introducing a hydrophilic epoxy group to the surface of the latex particles to be agglomerated, so that the agglomerating agent can be more easily entangled and bridged with the latex particles. The invention can conveniently regulate and control the particle size and the particle size distribution of the finally prepared large-size latex particles by controlling the stirring speed, the adding amount of the agglomerating agent and the concentration of the agglomerating agent.

The technical scheme of the invention is as follows:

a preparation method of polyacrylate latex particles with large particle size comprises the following steps:

(1) synthesis of the latex to be agglomerated

Adding a first emulsifier and first deionized water into a reactor, stirring for 10-30 minutes, then adding n-butyl acrylate and a crosslinking agent, continuing stirring for 10-30 minutes, heating under the conditions of nitrogen atmosphere and condensation reflux, adding a first initiator when the temperature is increased to 65-80 ℃, and carrying out heat preservation reaction for 1-3 hours; then, adding a second emulsifier and second deionized water, then dropwise adding the mixed monomer for 1-3 hours, dropwise adding a second initiator for 2-5 times in the dropwise adding process, and after dropwise adding, carrying out heat preservation reaction for 3-5 hours to obtain a to-be-agglomerated latex;

the mixed monomer consists of n-butyl acrylate and glycidyl methacrylate, and the mass ratio of the n-butyl acrylate to the glycidyl methacrylate is 100-200: 10 to 50; the mass ratio of the materials is as follows:

(2) synthesis of an agglomerating agent

Adding dimethylaminoethyl methacrylate, deionized water and a molecular weight regulator into another reactor, stirring for 30 minutes, adding a third initiator at 65-80 ℃ in a nitrogen atmosphere, condensing and refluxing, reacting for 3-5 hours in a heat preservation manner, and diluting by 2-10 times with water to obtain an agglomerating agent;

wherein the mass ratio of the dimethylaminoethyl methacrylate: deionized water: molecular weight regulator: and (3) a third initiator is 2-10: 50-100: 0.02-0.1: 0.02 to 0.1;

(3) agglomeration process

Heating the latex emulsion to be agglomerated to 25-65 ℃, adjusting the pH value of the latex emulsion to 4-7, stirring for 10-60 minutes at a low rotation speed (50-100 rpm), adding the agglomerating agent prepared in the step (2) at a high rotation speed (100-300 rpm), and continuously stirring for 20-60 minutes at a low rotation speed (50-100 rpm) to obtain large-particle-size latex after agglomeration;

wherein the mass ratio of the latex emulsion to be agglomerated is as follows: 50-100% of an agglomerating agent: 2-20;

in the step (1), the first emulsifier and the second emulsifier are both sodium dodecyl sulfate or sodium dodecyl benzene sulfonate;

in the step (1), the crosslinking agent is 1, 4-butanediol acrylate or allyl methacrylate;

in the step (1) and the step (2), the first initiator, the second initiator or the third initiator is potassium persulfate or ammonium persulfate; the first initiator, the second initiator or the third initiator are added in the form of solution, and the concentration of the solution is 0.2-1.5 g of initiator per 20-60 g of solution.

In the step (2), the molecular weight regulator is tert-dodecyl mercaptan or dodecyl mercaptan;

the invention has the substantive characteristics that:

the main methods for agglomeration reported so far, whether chemical agglomeration method (carboxylic acid or inorganic substance as agglomerating agent) and polymer latex agglomeration method (mostly polymer latex containing carboxylic acid as agglomerating agent), mostly use carboxylic acid to destroy part of emulsifier molecule layer in emulsion system, reduce emulsion system stability, then under the condition of stirring, latex particles are collided and fused to cause agglomeration, and small-particle-size latex particles are agglomerated into large-particle-size latex particles.

According to the invention, dimethyl aminoethyl methacrylate is utilized to prepare the agglomerating agent, the dimethyl aminoethyl methacrylate has strong hydrophilicity and can be dispersed in water, a hydrophilic polymer chain prepared from the dimethyl aminoethyl methacrylate is taken as the agglomerating agent, the agglomerating agent is added into the latex to be agglomerated, the surface hydrophilicity of the latex particle surface is increased by modifying glycidyl methacrylate on the surface of the latex particle to be agglomerated, the surface energy of the particle is reduced, the agglomerating agent molecules are more likely to approach the latex particle to be agglomerated under the stirring condition, the epoxy group on the surface of the latex particle to be agglomerated can carry out ring-opening reaction under the acidic condition, the tertiary amino group on the agglomerating agent molecules can form hydrogen bonds with the hydroxyl group generated after the ring-opening of the epoxy group on the surface of the latex particle to be agglomerated, and the agglomeration process is more likely to occur under the common driving of the surface energy and the hydrogen bonds. And the particle size of the agglomerated latex particle can be controlled by controlling the concentration and molecular weight of the agglomerating agent and the amount of epoxy groups of the latex particle to be agglomerated.

The invention has the beneficial effects that:

the invention can effectively increase the particle size of the latex particles to be agglomerated, and can increase the particle size of the latex particles to be agglomerated to be 60-80 nm to 160-400 nm. The polyacrylate latex particles prepared by the method have larger particle size, can better inhibit the development of silver streaks and bridge two banks of cracks when dispersed in an SAN modified matrix, and the prepared ASA resin has excellent impact resistance. Compared with a polymer latex agglomeration method, the method disclosed by the invention is simpler and more convenient to operate, and the particle size and particle size distribution of latex particles are good in controllability and repeatability. The traditional chemical agglomeration method has the defects that an agglomerating agent has great influence on the stability of the emulsion, and the particle size of particles in the agglomerated latex is continuously increased along with the prolonging of the storage time. The epoxy group introduced to the surface of the latex particle to be agglomerated can drive the agglomeration process to occur on one hand, and can effectively improve the mechanical property of the prepared ASA resin on the other hand due to the existence of the epoxy group.

Drawings

FIG. 1 is a schematic illustration of the agglomeration principle of the present invention;

FIG. 2 is a histogram of the particle size distribution of the latex obtained in step (1) in example 1;

FIG. 3 is a histogram of the particle size distribution of the latex obtained in step (2) of example 1.

Detailed Description

Example 1.

(1) Adding 0.75g of sodium dodecyl sulfate and 700g of deionized water into a 1L four-neck flask, stirring for 30 minutes at room temperature, then adding 37.51g of n-butyl acrylate and 0.375g of 1, 4-butanediol diacrylate into the four-neck flask, stirring for 30 minutes, introducing nitrogen, switching on a condenser tube, heating, adding 35g of an aqueous solution dissolved with 0.75g of potassium persulfate into the four-neck flask at 75 ℃, and carrying out heat preservation reflux reaction for 1 hour. Then, 0.47g of sodium lauryl sulfate and 20g of deionized water were added to a four-necked flask, 150g of n-butyl acrylate and 36g of glycidyl methacrylate were uniformly mixed, and the mixture was dropped into the four-necked flask over two hours, and 50g of an aqueous solution in which 1.27g of potassium persulfate was dissolved was added to the four-necked flask in three times during the dropping. And after the dropping of the mixed monomer is finished, keeping the temperature for 5 hours to react, and obtaining the latex to be agglomerated. The latex obtained was measured by a dynamic light scattering laser particle sizer of Malvern, UK to have an average particle diameter of latex particles of 71nm and a dispersion index PDI value of 0.029.

(2) Adding 4.01g of dimethylaminoethyl methacrylate, 0.04g of tert-dodecyl mercaptan and 75g of deionized water into a 100mL four-neck flask, introducing nitrogen, connecting a condenser tube, stirring at the stirring speed of 150rpm for 30 minutes, then starting to heat up, adding 5g of an aqueous solution dissolved with 0.04g of potassium persulfate into the four-neck flask at 70 ℃, carrying out heat preservation and reflux reaction for 3 hours, and diluting the obtained product by 5 times to obtain the agglomerant.

(3) Adding 50.17g of the latex to be agglomerated prepared in the step (1) into a 250mL four-mouth bottle, stirring at 100rpm, heating to 60 ℃, and adjusting the pH of the solution to 4-5. 5.10g of the agglomerating agent prepared in the step (2) was added to a four-necked flask at a rate of 9 g/hr until a small amount of precipitate appeared in the flask, and the dropwise addition was completed to obtain a large-particle-size latex after agglomeration. The latex obtained had an average particle diameter of latex particles of 208nm and a dispersion index PDI value of 0.252 as measured with a dynamic light scattering laser particle sizer of Malvern, UK.

Example 2.

(1) Adding 0.75g of sodium dodecyl sulfate and 700g of deionized water into a 1L four-mouth bottle, stirring for 30 minutes at room temperature, then adding 37.50g of n-butyl acrylate and 0.375g of 1, 4-butanediol diacrylate into the four-mouth bottle, stirring for 30 minutes, introducing nitrogen, switching on a condenser tube, heating, adding 35g of an aqueous solution dissolved with 0.75g of potassium persulfate into the four-mouth bottle at 75 ℃, and carrying out heat preservation reaction for 1 hour. Then 0.47g of sodium dodecyl sulfate and 20g of deionized water were added to a four-necked flask, 150g of n-butyl acrylate and 36g of glycidyl methacrylate were mixed uniformly, the mixture was added to the four-necked flask over two hours, and 50g of an aqueous solution in which 1.27g of potassium persulfate was dissolved was added to the four-necked flask in three times during the dropwise addition. And after the dropping of the mixed monomer is finished, keeping the temperature for 5 hours to react, and obtaining the latex to be agglomerated. The latex obtained had an average particle diameter of latex particles of 79nm and a dispersion index PDI value of 0.016 as measured by a dynamic light scattering laser particle sizer of Malvern, England.

(2) Adding 4.04g of dimethylaminoethyl methacrylate, 0.04g of tert-dodecyl mercaptan and 75g of deionized water into a 100mL four-neck flask, introducing nitrogen, connecting a condenser tube, stirring at the stirring speed of 150rpm for 30 minutes, then starting to heat up, adding 5g of an aqueous solution dissolved with 0.04g of potassium persulfate into the four-neck flask at 70 ℃, carrying out heat preservation and reflux reaction for 3 hours, and diluting the obtained product by 2 times to obtain the agglomerant.

(3) Adding 50.17g of the latex to be agglomerated prepared in the step (1) into a 250mL four-mouth bottle, stirring at 100rpm, heating to 60 ℃, and adjusting the pH of the solution to 4-5. 5.02g of the agglomerating agent prepared in the step (2) was added to a four-necked flask at a rate of 9 g/hr until a small amount of precipitate appeared in the flask, and the dropwise addition was completed to obtain a large-particle-size latex after agglomeration. The latex obtained had an average particle diameter of latex particles of 320nm and a dispersion index PDI value of 0.416 as measured with a dynamic light scattering laser particle sizer of Malvern, UK.

Example 3.

(1) Adding 0.75g of sodium dodecyl sulfate and 700g of deionized water into a 1L four-mouth bottle, stirring for 30 minutes at room temperature, then adding 37.50g of n-butyl acrylate and 0.375g of 1, 4-butanediol diacrylate into the four-mouth bottle, stirring for 30 minutes, introducing nitrogen, switching on a condenser tube, heating, adding 35g of an aqueous solution dissolved with 0.75g of potassium persulfate into the four-mouth bottle at 75 ℃, and carrying out heat preservation reaction for 1 hour. Then 0.47g of sodium dodecyl sulfate and 20g of deionized water were added to a four-necked flask, 150g of n-butyl acrylate and 36g of glycidyl methacrylate were mixed uniformly, the mixture was added to the four-necked flask over two hours, and 50g of an aqueous solution in which 1.27g of potassium persulfate was dissolved was added to the four-necked flask in three times during the dropwise addition. And after the dropping of the mixed monomer is finished, keeping the temperature for 5 hours to react, and obtaining the latex to be agglomerated. The latex obtained had an average particle diameter of latex particles of 75nm and a dispersion index PDI value of 0.037 as measured with a dynamic light scattering laser particle sizer of Malvern, UK.

(2) Adding 4.10g of dimethylaminoethyl methacrylate, 0.04g of tert-dodecyl mercaptan and 75g of deionized water into a 100mL four-neck flask, introducing nitrogen, connecting a condenser tube, stirring at the stirring speed of 150rpm for 30 minutes, then starting to heat up, adding 5g of an aqueous solution dissolved with 0.04g of potassium persulfate into the four-neck flask at 70 ℃, keeping the temperature for reaction for 3 hours, and diluting the obtained product by 10 times to obtain the agglomerant.

(3) Adding 50.17g of the latex to be agglomerated prepared in the step (1) into a 250mL four-mouth bottle, stirring at 100rpm, heating to 60 ℃, and adjusting the pH of the solution to 4-5. 7.51g of the agglomerating agent prepared in step (2) was added to a four-necked flask at a rate of 9 g/hr until a small amount of precipitate appeared in the flask, and the dropwise addition was completed to obtain a large-particle-size latex after agglomeration. The latex obtained had an average particle diameter of 188nm and a dispersion index PDI value of 0.275 as measured with a dynamic light scattering laser particle sizer of Malvern, UK.

Example 4

(1) Adding 0.75g of sodium dodecyl sulfate and 700g of deionized water into a 1L four-neck flask, stirring for 30 minutes at room temperature, then adding 37.52g of n-butyl acrylate and 0.375g of 1, 4-butanediol diacrylate into the four-neck flask, stirring for 30 minutes, introducing nitrogen, switching on a condenser tube, heating, adding 35g of an aqueous solution dissolved with 0.75g of potassium persulfate into the four-neck flask at 75 ℃, and carrying out heat preservation reaction for 1 hour. Then, 0.47g of sodium lauryl sulfate and 20g of deionized water were added to a four-necked flask, 150g of n-butyl acrylate and 12g of glycidyl methacrylate were uniformly mixed, the mixture was added to the four-necked flask over two hours, and 50g of an aqueous solution in which 1.27g of potassium persulfate was dissolved was added to the four-necked flask in three times during the dropwise addition. And after the dropping of the mixed monomer is finished, keeping the temperature for 5 hours to react, and obtaining the latex to be agglomerated. The latex obtained was measured by a dynamic light scattering laser particle sizer of Malvern, UK to have an average particle diameter of latex particles of 72nm and a dispersion index PDI value of 0.025.

(2) Adding 4.05g of dimethylaminoethyl methacrylate, 0.04g of tert-dodecyl mercaptan and 75g of deionized water into a 100mL four-neck flask, introducing nitrogen, connecting a condenser tube, stirring at the stirring speed of 150rpm for 30 minutes, then starting to heat up, adding 5g of an aqueous solution dissolved with 0.04g of potassium persulfate into the four-neck flask at 70 ℃, keeping the temperature for reaction for 3 hours, and diluting the obtained product by 10 times to obtain the agglomerant.

(3) Adding 50.17g of the latex to be agglomerated prepared in the step (1) into a 250mL four-mouth bottle, stirring at 100rpm, heating to 60 ℃, and adjusting the pH of the solution to 6-7. 7.48g of the agglomerating agent prepared in step (2) was added to a four-necked flask at a rate of 9 g/hr until a small amount of precipitate appeared in the flask, and the dropwise addition was completed to obtain a large-particle-size latex after agglomeration. The latex obtained had an average particle diameter of 163nm and a dispersion index PDI value of 0.273 as measured with a dynamic light scattering laser particle sizer of Malvern, UK.

As can be seen from FIGS. 2 and 3 in comparative example 1, the particle size of the latex after agglomeration is significantly increased compared to the latex to be agglomerated; as can be seen from the comparison between the embodiment 1 and the embodiment 2, the particle size and distribution of the agglomerated large-particle-size latex particles can be regulated and controlled by regulating the concentration of the agglomerating agent; as can be seen from the comparison of example 3 with example 4, the amount of glycidyl methacrylate in the latex particles to be agglomerated and the pH of the latex to be agglomerated likewise influence the particle size and the particle size distribution of the particles in the latex after agglomeration. In conclusion, the method is real and effective, the operation is simple and convenient, and the particle size distribution of the prepared latex particles with large particle size are controllable.

The invention is not the best known technology.