阅读说明：本技术 一种多分支型分散剂及其制备方法 (Multi-branch type dispersing agent and preparation method thereof ) 是由 施晓旦 孔祥康 王虎 于 2020-04-23 设计创作，主要内容包括：本发明公开了一种多分支型分散剂,其制备方法包括如下步骤：采用初始链转移试剂与多元醇按化学计量比反应获得链转移试剂,然后与单体发生RAFT聚合,经后处理得到所述多分支型分散剂,所述初始链转移试剂为三硫代碳酸或三硫代碳酸酯。本发明通过选取特殊结构的多元醇与初始链转移试剂反应制备出具有特定空间结构、多活性位点的链转移试剂,再选取合适单体进行RAFT聚合反应,制备出多分支型分散剂,由于该分散剂分子具有很多分支,在溶液中舒展开来,相互交错形成了一种网状结构,不仅使得分散后的浆料粘度更低,在长时间储存和运输中指标和性能也都能保持稳定,给实际的生产和使用带来了极大的便利,同时对于保证纸张的品质起到了重要的作用。(The invention discloses a multi-branch type dispersing agent, and a preparation method thereof comprises the following steps: reacting an initial chain transfer reagent with polyhydric alcohol according to a stoichiometric ratio to obtain a chain transfer reagent, carrying out RAFT polymerization on the chain transfer reagent and a monomer, and carrying out post-treatment to obtain the multi-branch dispersing agent, wherein the initial chain transfer reagent is trithiocarbonate or trithiocarbonate. According to the invention, polyol with a special structure is selected to react with an initial chain transfer reagent to prepare a chain transfer reagent with a specific spatial structure and multiple active sites, and then a proper monomer is selected to carry out RAFT polymerization reaction to prepare the multi-branch type dispersing agent.)

1. A preparation method of a multi-branch dispersant is characterized by comprising the following steps: reacting an initial chain transfer reagent with polyhydric alcohol according to a stoichiometric ratio to obtain a chain transfer reagent, carrying out RAFT polymerization on the chain transfer reagent and a monomer, and carrying out post-treatment to obtain the multi-branch dispersing agent, wherein the initial chain transfer reagent is trithiocarbonate or trithiocarbonate.

2. The method of claim 1, wherein the initial chain transfer agent is bis (carboxymethyl) trithiocarbonic acid.

3. The method of claim 1, wherein the initial chain transfer agent is at least one of S, S ' -bis (α ' -methyl- α "-acetic acid) trithiocarbonate, S ' -dibenzylformiato trithiocarbonate.

4. The method of claim 1, wherein the polyol is at least one selected from the group consisting of 1, 3-propanediol, glycerol, erythritol, pentaerythritol, and 2, 2-dimethylolbutanol.

5. The method of claim 4, wherein the polyol is glycerol or pentaerythritol.

6. The method of claim 1, wherein the monomer is selected from at least one of acrylic acid, methacrylic acid, maleic acid, p-styrenesulfonic acid, p-styreneformic acid, and p-styreneacetic acid.

7. The method of claim 6, wherein the monomer is acrylic acid or maleic acid.

8. The method according to any one of claims 1 to 7, comprising the steps of:

feeding the initial chain transfer reagent and polyhydric alcohol according to a stoichiometric ratio, adding a proper amount of solvent and a dehydration condensing agent, fully reacting under the conditions of normal temperature, normal pressure and no oxygen, removing insoluble substances, and evaporating the solvent to obtain the chain transfer reagent;

adding an effective amount of chain transfer reagent, a proper amount of initiator, reducer and water into the monomer, fully dissolving and uniformly mixing, and fully reacting under an anaerobic condition;

and step three, cooling to room temperature after the reaction is finished, and adjusting the pH value of a reaction product to 3-5 by using an alkali liquor to obtain the multi-branch type dispersing agent.

9. The method of claim 8, wherein the weight parts of each component are as follows:

alkali liquor and water in proper amount.

10. A multi-branched dispersant prepared by the process of any one of claims 1 to 9.

Technical Field

The invention relates to the field of dispersant preparation, in particular to a multi-branch type polymeric dispersant for papermaking and a preparation method thereof.

Background

The dispersant is an important assistant in grinding pigment such as calcium carbonate or filler and dispersing paint, and can improve grinding efficiency, particle size, viscosity, stability of slurry and paint, smoothness, whiteness, ink absorbency, surface strength, coating gloss, printing gloss, etc. The sodium salt of the polyvinyl acid polymer is widely applied in the field, wherein the low molecular weight sodium polyacrylate water solution becomes a main product in the field with excellent dispersibility. However, in terms of the current production process and method, the grinding performance of common products on the market is still to be improved, the performance controllability is not good, and the effect stability is poor; one of the main reasons for this is that the current polymeric dispersants are mostly linear structures. The linear molecules are easy to curl and agglomerate, and the spatial configuration and distribution are unstable, so that the performance of the slurry obtained by grinding is unstable, and the method has a plurality of problems in practical production application. And most of the existing macromolecular dispersants are prepared by adopting common free radical polymerization reaction, and have no good controllability on molecular weight and molecular weight distribution, which directly influences the final performance of paper.

Research on living controlled radical polymerization has also been carried out for a long time, wherein RAFT polymerization shows more advantages because the types of raw materials used are few, the chain transfer reagent is easy to prepare, and the molecular structure can be designed to a certain extent; further, studies on dendrimers have been increasing in recent years, and many linear molecules have been found to have excellent properties, so that development and applications have been gradually increased. The idea of designing and synthesizing the dendritic macromolecule is integrated into the design and synthesis of the dispersant, and the advantages of the dendritic macromolecule and the dispersant are combined to prepare the controllable multi-branch dispersant, which becomes an important subject in the field.

Disclosure of Invention

The invention aims to provide a multi-branch dispersing agent based on RAFT polymerization and a preparation method thereof, so as to solve the defects in the prior art.

The invention is realized by the following technical scheme:

a preparation method of a multi-branch type dispersing agent comprises the following steps: reacting an initial chain transfer reagent with polyhydric alcohol according to a stoichiometric ratio to obtain a chain transfer reagent, carrying out RAFT polymerization on the chain transfer reagent and a monomer, and carrying out post-treatment to obtain the multi-branch dispersing agent, wherein the initial chain transfer reagent is trithiocarbonate or trithiocarbonate.

The initial chain transfer agent is preferably di (carboxymethyl) trithiocarbonic acid.

More preferably, the initial chain transfer agent is at least one of S, S '-bis (α' -methyl- α '-acetic acid) trithiocarbonate and S, S' -dibenzylformiato trithiocarbonate.

The polyalcohol is at least one selected from 1, 3-propylene glycol, glycerol, erythritol, pentaerythritol and 2, 2-dimethylolbutanol, preferably glycerol or pentaerythritol.

The monomer is at least one of acrylic acid, methacrylic acid, maleic acid, p-styrene sulfonic acid, p-styrene formic acid and p-styrene acetic acid, and acrylic acid or maleic acid is preferred.

As a preferred technical scheme, the preparation method of the multi-branch type dispersing agent comprises the following steps:

feeding the initial chain transfer reagent and polyhydric alcohol according to a stoichiometric ratio, adding a proper amount of solvent and a dehydration condensing agent, fully reacting under the conditions of normal temperature, normal pressure and no oxygen, removing insoluble substances, and evaporating the solvent to obtain the chain transfer reagent;

adding an effective amount of chain transfer reagent, a proper amount of initiator, reducer and water into the monomer, fully dissolving and uniformly mixing, and fully reacting under an anaerobic condition;

and step three, cooling to room temperature after the reaction is finished, and adjusting the pH value of a reaction product to 3-5 by using an alkali liquor to obtain the multi-branch type dispersing agent.

As a further preferable technical scheme, the weight parts of the components are as follows:

alkali liquor and water in proper amount.

The amounts of the solvent and the dehydration condensation agent to be used are easily adjusted by those skilled in the art depending on the dissolution state of the raw materials and in order to complete the reaction sufficiently. The alkaline solution is mainly used for adjusting the pH value of the product, and reagents commonly used in the field, such as but not limited to sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, ammonia water and the like, can be selected, and a sodium hydroxide solution with a mass concentration of 32% is preferred, and the dosage is determined according to the final pH value of the product. The amount of water used is not particularly limited and can be adjusted by one skilled in the art according to the dispersive mixing of the components, the sufficiency of solution polymerization and the solid content of the final product. Preferably, the amount of water is 90-230 parts.

The solvent is preferably Tetrahydrofuran (THF), and the dehydration condensation agent is preferably Dicyclohexylcarbodiimide (DCC).

The initiator and the reducing agent are not particularly required, and components conventional in the art may be selected. Wherein the initiator can be selected from at least one of sodium persulfate, potassium persulfate, ammonium persulfate, hydrogen peroxide, tert-butyl hydroperoxide, cyclohexanone peroxide, benzoyl peroxide, azo initiators and percarbonate; the reducing agent may be selected from, but not limited to, at least one of sodium bisulfite, sodium sulfite, sodium metabisulfite, potassium sulfite, sodium thiosulfate, N-dimethylaniline, tartaric acid, sodium formaldehyde sulfoxylate, ferrous sulfate, N-dodecyl mercaptan, t-dodecyl mercaptan, ferrous chloride, tetraethylene imine, diethylenetriamine, tetraethylene pentamine, ferrous pyrophosphate, sodium phosphite, sodium hexametaphosphate, sodium hypophosphite, sodium dihydrogen phosphate, methylamine, ethylamine, glucose, fructose, vitamin C.

Preferably, in the second step, the reaction temperature is controlled to be 60-90 ℃, and the reaction time is 6-10 h.

The multi-branch dispersing agent prepared by the method can be used as a ground dispersing agent of heavy calcium carbonate.

According to the invention, polyol with a special structure is selected to be combined with an initial chain transfer reagent through reaction to prepare a chain transfer reagent (CTA) with a specific spatial structure and multiple active sites, then a proper monomer is selected to perform RAFT polymerization reaction to prepare a series of multi-branch type polymers, and the multi-branch type dispersing agent is obtained through post-treatment. Because the molecules of the dispersant have a plurality of branches, the dispersant is spread in the solution and mutually staggered to form a network structure, the viscosity of the dispersed slurry is lower, the indexes and the performance can be kept stable in long-time storage and transportation, great convenience is brought to actual production and use, and an important role is played in ensuring the quality of paper. This is certainly a new research hotspot in the field of dispersants, and it is believed that such dispersants will certainly show their own value in the paper industry in the future.

The invention adopts the RAFT polymerization method, integrates the idea of dendrimer design and synthesis into the design and synthesis of the dispersant, and combines the advantages of the two to prepare the controllable multi-branch dispersant. The multiple control from molecular weight and molecular weight distribution to spatial structure enables the dispersant to show unique characteristics and application advantages. The method is also convenient for realizing industrialization and is expected to be widely applied in the papermaking industry.

Detailed Description

The invention is illustrated below by means of specific examples, without being restricted thereto. All the raw materials are conventional commercial products unless otherwise specified.