阅读说明：本技术 一种二氧化碳附聚制备大粒径乳胶的方法 (Method for preparing large-particle-size latex by carbon dioxide agglomeration ) 是由 刘伯军 罗雪妍 张明耀 张会轩 谭志勇 杜帅 胡艺伟 刘香池 于 2019-10-25 设计创作，主要内容包括：一种二氧化碳附聚制备大粒径乳胶粒子的方法,属于合成橡胶领域。旨在利用二氧化碳在水中形成碳酸,碳酸进一步电离出氢离子的原理降低胶乳的pH值,进而压缩乳胶粒子表面双电荷厚度,促进乳胶粒子进行附聚,最终制备出大粒径胶乳。此方法优势在于,二氧化碳在胶乳中呈现出弱酸性质,酸性较弱,不会导致胶乳直接破乳,此外,碳酸受热之后不稳定,可以通过加热的方法将附聚后胶乳中的碳酸除去,提高胶乳稳定性。此方法操作简单,安全环保,价格低廉,适用于工业化生产。(A method for preparing large-particle-size latex particles by carbon dioxide agglomeration belongs to the field of synthetic rubber. The method aims to reduce the pH value of the latex by utilizing the principle that carbon dioxide forms carbonic acid in water and the carbonic acid further ionizes hydrogen ions, so that the surface double-charge thickness of latex particles is compressed, the agglomeration of the latex particles is promoted, and the latex with large particle size is finally prepared. The method has the advantages that the carbon dioxide presents weak acid property in the latex, the acidity is weak, the latex is not directly demulsified, in addition, the carbonic acid is unstable after being heated, and the carbonic acid in the agglomerated latex can be removed by a heating method, so that the latex stability is improved. The method is simple to operate, safe, environment-friendly, low in price and suitable for industrial production.)

1. A method for preparing large-particle-size latex by carbon dioxide agglomeration comprises the following steps:

(1) putting 0.2-5 parts by mass of an emulsifier, 0.2-8 parts by mass of an electrolyte, 0.2-5 parts by mass of an initiator and 60-80 parts by mass of desalted water into a reaction kettle, introducing nitrogen into the reaction kettle to replace air in the kettle for 2-3 times, and starting a stirring device to completely dissolve all the auxiliaries. And then, injecting 20-60 parts of reaction monomers into the kettle, regulating the rotating speed of the reaction kettle to 50-400 rpm, raising the temperature of the reaction kettle to 55-85 ℃, and starting a polymerization reaction for 2-18 hours to prepare the small-particle-size polymer latex.

(2) And maintaining the temperature of the reaction kettle at 55-85 ℃, introducing carbon dioxide gas into the latex with the small particle size in the reaction kettle, maintaining the pressure of the reaction kettle at 0.1-5 kg for 10-30 min, and recovering the carbon dioxide gas.

(3) And stopping heating the reaction kettle, opening the reaction kettle, and discharging to obtain the large-particle-size polymer latex.

2. The method for preparing large-particle-size latex by agglomerating carbon dioxide as claimed in claim 1, wherein the polymerization monomers used in the present invention are: butadiene, isoprene, butyl acrylate, isooctyl acrylate, styrene, acrylonitrile, methyl methacrylate, butyl methacrylate, isooctyl methacrylate and other monomers.

3. The method for preparing large-particle-size latex by agglomerating carbon dioxide as claimed in claim 1, wherein the emulsifier used in the present invention is: disproportionated abietic acid soap, fatty acid soap, potassium oleate, sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, polyoxyethylene ether and/or sodium alkyl naphthalene sulfonate.

4. The method for preparing the emulsion with large particle size by agglomerating the carbon dioxide as claimed in claim 1, wherein the electrolyte used in the invention is one or more of potassium carbonate, sodium bicarbonate and potassium bicarbonate.

5. The method for preparing large-particle-size latex by agglomerating carbon dioxide as claimed in claim 1, wherein the initiator used in the present invention is: one or more of ammonium persulfate, potassium persulfate, sodium persulfate, azodiisobutyronitrile, benzoyl peroxide and cumene hydroperoxide.

6. The method for preparing the emulsion with large particle size by agglomerating the carbon dioxide as claimed in claim 1, wherein the agglomeration pressure used in the invention is 0.1-5 kg.

Technical Field

The invention belongs to the field of synthetic rubber, and particularly relates to a preparation method of large-particle-size latex.

Background

The large-particle-size polymer latex has the advantages of low viscosity, good fluidity and high drying speed, and is widely applied to the fields of synthetic rubber, papermaking, synthetic resin and the like. In general, the production cycle of the large-particle size latex is long, for example, the preparation time of the large-particle size butadiene latex can reach tens of hours at most, which severely limits the industrial production efficiency and also increases the production cost of the large-particle size latex. Therefore, the short-cycle preparation of large-particle-size latex is a hot spot of research in the industrial field.

The agglomeration method is a common method for industrially preparing the latex with large particle size at present, the agglomeration method is to directly agglomerate the latex with small particle size into the latex with large particle size by physical or chemical means, and the method has short period and high production efficiency. Depending on the agglomeration means, they can be simply classified into: pressure agglomeration, polymer agglomeration, acid agglomeration, electrolyte agglomeration, low temperature agglomeration, and the like. Among them, acid agglomeration is the most common method in the industrial production field. The acid liquid used for acid agglomeration is typically low-concentration acetic acid or acetic anhydride. In the acid agglomeration process, the pH value of the latex is reduced by adding the acid, the double-charge thickness on the surface of the latex particles is compressed, the coalescence of the latex particles is promoted, and the aim of preparing the latex with large particle size is finally achieved. At the later stage of the acid agglomeration process, alkali liquor needs to be introduced to regulate and control the pH value of the latex so as to maintain the stability of the latex. The limitation of acid agglomeration is that impurities are introduced into a system, the system composition is changed, the solid content of acid agglomeration latex is generally not high and can only be maintained at about 30-40%, and the production efficiency of acid agglomeration is reduced, so that the development of a new agglomeration method is always a technical problem concerned in the field of large-particle-size latex preparation.

Carbon dioxide is a colorless, tasteless, non-toxic gas that spontaneously forms carbonic acid in water, which is less acidic, but which also ionizes hydrogen ions, lowering the pH of its water. Based on this principle, there are distinct advantages to agglomerating small particle size latexes using carbon dioxide as an agglomerating agent. Micro & Nano Letters (2018, 13: 1486-. Therefore, the problem of how to effectively agglomerate by using carbon dioxide to prepare large-particle-size and narrow-distribution polymer latex is that no effective method is available in the industry at present.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: after the synthesis of the small-particle-size latex is finished, introducing carbon dioxide gas into the system at high pressure, wherein the high-pressure condition is favorable for increasing the solubility of carbon dioxide, and can quickly reduce the pH value of the latex, so that the agglomeration of the small-particle-size latex is quickly promoted under the action of mechanical stirring, and the large-particle-size polymer latex is finally prepared. After the large-particle-size latex is prepared, the carbon dioxide in the large-particle-size latex can be automatically removed for recovery, and the method is efficient, environment-friendly, safe and economical. The invention provides a method for preparing large-particle-size latex by carbon dioxide agglomeration, which comprises the following specific steps:

(1) putting 0.2-5 parts by mass of an emulsifier, 0.2-8 parts by mass of an electrolyte, 0.2-5 parts by mass of an initiator and 60-80 parts by mass of desalted water into a reaction kettle, introducing nitrogen into the reaction kettle to replace air in the kettle for 2-3 times, and starting a stirring device to completely dissolve all the auxiliaries. And then, injecting 20-60 parts of reaction monomers into the kettle, regulating the rotating speed of the reaction kettle to 50-400 rpm, raising the temperature of the reaction kettle to 55-85 ℃, and starting a polymerization reaction for 2-18 hours to prepare the small-particle-size polymer latex.

(2) And maintaining the temperature of the reaction kettle at 55-85 ℃, introducing carbon dioxide gas into the latex with the small particle size in the reaction kettle, maintaining the pressure of the reaction kettle at 0.1-5 kg for 10-30 min, and recovering the carbon dioxide gas.

(3) And stopping heating the reaction kettle, opening the reaction kettle, and discharging to obtain the large-particle-size polymer latex.

The polymerization monomers used in the present invention are: butadiene, isoprene, butyl acrylate, isooctyl acrylate, styrene, acrylonitrile, methyl methacrylate, butyl methacrylate, isooctyl methacrylate and other monomers.

The emulsifiers used in the present invention are: disproportionated rosin acid soap, fatty acid soap, potassium oleate, sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, polyoxyethylene ether and/or alkyl naphthalene sulfonate;

the electrolyte used in the invention is one or a mixture of more of potassium carbonate, sodium bicarbonate and potassium bicarbonate.

The initiators used in the present invention are: one or more of ammonium persulfate, potassium persulfate, sodium persulfate, azodiisobutyronitrile, benzoyl peroxide and cumene hydroperoxide.

The agglomeration pressure used in the present invention is 0.1 to 5 kg.

The invention has the beneficial effects that: the high-pressure carbon dioxide has short agglomeration time, high efficiency, pure product and relatively narrow particle size distribution, and the agglomeration agent can be recycled.

Detailed Description

The following examples are given to better understand the invention, but do not limit it in any way.