阅读说明：本技术 分散剂、研磨分散剂、造纸涂布用涂料 (Dispersant, grinding dispersant and coating for papermaking coating ) 是由 郑保健 戴玲 于 2020-12-31 设计创作，主要内容包括：本发明公开了一种分散剂、研磨分散剂、造纸涂布用涂料。研磨分散剂按如下步骤制得：向底料中缓慢滴加功能性混合单体,调节温度至80－95℃,采用氧化、还原体系引发共聚,滴加反应180－300min,保温反应30－120min,保温反应后,降温至30－40℃以下,用液碱进行pH值调节至4.0－7.0即得。利用本发明的研磨分散剂能在研磨碳酸钙粒子周围形成更加稳固的双电子层结构；同时该研磨分散剂聚合物在碳酸钙的研磨过程中可以在浆钙粒子周围形成空间立体网状结构,在降粘的同时能够进一步提高研磨碳酸钙的稳定性及改善浆钙粒径,提高浆钙固含量,从而降低能耗,并且能较大提高成纸的光泽度、平滑度等指标,且研磨分散剂用量少,效果好,成本低。(The invention discloses a dispersant, a grinding dispersant and a coating for papermaking coating. The grinding dispersant is prepared by the following steps: slowly dripping functional mixed monomers into the backing material, regulating the temperature to 80-95 ℃, initiating copolymerization by adopting an oxidation and reduction system, dripping for reaction for 180-300 min, carrying out heat preservation for reaction for 30-120 min, cooling to below 30-40 ℃ after the heat preservation reaction, and regulating the pH value to 4.0-7.0 by using liquid alkali to obtain the catalyst. The grinding dispersant can form a more stable double-electronic-layer structure around the ground calcium carbonate particles; meanwhile, the grinding dispersant polymer can form a spatial three-dimensional network structure around the slurry calcium particles in the grinding process of calcium carbonate, can further improve the stability of the ground calcium carbonate, improve the particle size of the slurry calcium and increase the solid content of the slurry calcium while reducing viscosity, thereby reducing energy consumption, greatly improving the indexes of the glossiness, smoothness and the like of finished paper, and having the advantages of less consumption of the grinding dispersant, good effect and low cost.)

1. The dispersing agent is characterized by being prepared from the following components in parts by weight:

the functional monomer is at least one selected from 1, 4-butanediol dimethacrylate, diethylene glycol dimethacrylate and triethylene glycol dimethacrylate.

2. The dispersant of claim 1, prepared by the steps of:

(1) stirring and mixing acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, methoxy polyethylene glycol itaconic acid monoester, benzyl phenylacrylate and functional monomer, and dissolving the solid completely for later use;

(2) preparing a dropping liquid A and a dropping liquid B while performing the step (1), and dissolving the oxidant in a proper amount of water to prepare a solution A; dissolving the reducing agent in a proper amount of water to prepare a solution B;

(3) adding bottom water into a reaction container, uniformly stirring and heating, keeping the temperature and stirring for 5-15 min at the temperature of 75-85 ℃, dropwise adding a dropwise adding liquid A, B into the reaction container when the temperature of the system rises to 80-95 ℃, dropwise adding the mixture obtained in the step (1) to react, keeping the temperature at 80-95 ℃, keeping the temperature for reaction for 300min after reaction for 180-120 min, keeping the temperature for reaction for 30-120 min, and cooling to obtain the dispersing agent.

3. The dispersant of claim 1, wherein the oxidant is selected from at least one of ammonium persulfate, potassium persulfate, sodium persulfate, dibenzoyl peroxide, or azobisisobutyronitrile.

4. The dispersant of claim 1, wherein the reducing agent is selected from at least one of sodium metabisulfite, sodium bisulfite, and sodium hypophosphite.

5. A grinding dispersion agent, which is obtained by neutralizing the dispersion agent according to any one of claims 1 to 4 with an alkaline agent to a pH of 4.0 to 7.0.

6. The abrasive dispersant of claim 5, wherein said alkaline agent is a liquid alkali in an amount of 48%.

7. The milldispersant according to claim 5, characterized in that the solids content of the milldispersant is not less than 35%.

8. A coating material for papermaking coating, which is prepared by using the polishing dispersant as set forth in claim 5.

Technical Field

The invention relates to the technical field of high molecular dispersants, and particularly relates to a dispersant, a grinding dispersant and a coating for papermaking coating.

Background

Calcium carbonate is used in papermaking coatings because of its high whiteness, low cost, good ink absorption, and the like, especially natural Ground Calcium Carbonate (GCC) is in great demand in papermaking coatings. Nowadays, the paper making industry is developing towards scale and high speed, the paper making coating is developing towards higher solid content, and the solid content of some paper making coatings is more than 72%, so that the dispersion and suspension performance of the coating are also more challenging.

The common dispersing agent is adsorbed on the surface of inorganic pigment to generate steric hindrance and electrostatic repulsion, so that pigment particles can stably exist in a suspended state, the GCC coating with high solid content and low viscosity can be obtained, the grinding efficiency is greatly improved, and the grinding energy consumption can be saved.

With the development of coating processing technology, the requirement of coating grade superfine GCC coating for the particle size of less than 2 μm and up to 90% from 10 years ago is developed to the requirement of less than 1.5 μm and up to 98%, even 99% which are frequently seen in the market at present, and the requirement on the particle size distribution of the superfine GCC coating is higher and higher. In order to ensure the stability of the quality of the superfine calcium carbonate coating, better calcium carbonate grinding equipment and higher-quality special grinding dispersing agent are needed. In the grinding stage, the grinding dispersant is divided into a front-stage dispersant and a rear-stage dispersant. The latter stage dispersant has attracted more and more interest of the majority of papermaking workers due to the reasons of market demand, high added value and the like, in particular to the modified acrylic dispersant.

In the case of high calcium carbonate content, the use of conventional grinding dispersants leads to a high viscosity of the coating, and tends to cause flocculation of calcium carbonate, which is disadvantageous for grinding and coating, and the high particle size of calcium carbonate in the coating affects the coating effect and the quality of the finished paper.

Disclosure of Invention

In order to overcome the defects, the invention aims to provide a dispersing agent, a grinding dispersing agent and a coating for papermaking coating. The dosage of the grinding dispersant in the total calcium carbonate grinding process is lower, the effect is good, the cost is reduced, and the grinding dispersant is green and environment-friendly.

In order to achieve the above purpose, the invention provides a dispersant, which is prepared from the following components in parts by weight:

the functional monomer is at least one selected from 1, 4-butanediol dimethacrylate, diethylene glycol dimethacrylate and triethylene glycol dimethacrylate.

Further, the dispersant is prepared according to the following steps:

(1) stirring and mixing acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, methoxy polyethylene glycol itaconic acid monoester, benzyl phenylacrylate and functional monomer, and dissolving the solid completely for later use;

(2) preparing a dropping liquid A and a dropping liquid B while performing the step (1), and dissolving the oxidant in a proper amount of water to prepare a solution A; dissolving the reducing agent in a proper amount of water to prepare a solution B;

(3) adding bottom water into a reaction container, uniformly stirring and heating, keeping the temperature and stirring for 5-15 min at the temperature of 75-85 ℃, dropwise adding a dropwise adding liquid A, B into the reaction container when the temperature of the system rises to 80-95 ℃, dropwise adding the mixture obtained in the step (1) to react, keeping the temperature at 80-95 ℃, keeping the temperature for reaction for 300min after reaction for 180-120 min, keeping the temperature for reaction for 30-120 min, and cooling to obtain the dispersing agent.

Further, the oxidant is selected from at least one of ammonium persulfate, potassium persulfate, sodium persulfate, dibenzoyl peroxide or azobisisobutyronitrile.

Further, the reducing agent is at least one selected from sodium metabisulfite, sodium bisulfite and sodium hypophosphite.

The invention also provides a grinding dispersant, which is obtained by neutralizing the dispersant to pH 4.0-7.0 by using an alkaline agent.

Further, the alkali agent is liquid alkali with the content of 48%.

Further, the grinding dispersion has a solid content of not less than 35%.

The invention also provides a coating for papermaking coating, which is prepared by utilizing the grinding dispersant.

The invention has the following beneficial effects:

(1) according to the dispersant disclosed by the invention, monomers such as 2-acrylamide-2-methylpropanesulfonic acid, methoxy polyethylene glycol itaconic acid monoester and benzyl acrylate are introduced to synthesize a polyfunctional polymer taking an acrylic acid chain segment as a main chain structure and benzyl acrylate as a secondary chain rigid structure, so that the steric hindrance effect among calcium slurry particles is enhanced, and the end group of the copolymer has various strong polar groups, so that pigment particles can be better adsorbed, and a good dispersion viscosity reduction effect is achieved;

(2) by introducing at least one of various functional monomers, namely 1, 4-butanediol dimethacrylate, diethylene glycol dimethacrylate and triethylene glycol dimethacrylate, for graft modification, the number of charges in the unit area of the surface double-electron layer of the ground calcium carbonate is more, so that the calcium carbonate particles have a more stable double-electron layer structure; meanwhile, the grinding dispersant polymer can form a spatial three-dimensional network structure around the calcium slurry particles in the grinding process of calcium carbonate, further enhances the steric hindrance effect among the particles, and improves the stability of the ground calcium slurry system and the particle size of the calcium slurry.

(3) The dispersant of the invention can improve the content of calcium carbonate during grinding, reduce the viscosity of a system and reduce the flocculation of calcium carbonate.

(4) The coating of the invention can obviously improve the whiteness, smoothness and glossiness of the finished paper, reduce the dosage of the grinding dispersant and reduce the cost.

Detailed Description

The present invention is described in detail below with reference to specific embodiments so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making the scope of the present invention more clearly defined.

Example 1:

mixing, stirring and dissolving 100g of acrylic acid, 40g of 2-acrylamide-2-methylpropanesulfonic acid, 10g of methoxy polyethylene glycol itaconic acid monoester, 5g of benzyl phenylacrylate and 2g of 1, 4-butanediol dimethacrylate for later use;

dissolving 2g of ammonium persulfate into 18g of water to prepare an oxidant solution for later use while performing the step I; dissolving 5g of sodium metabisulfite into 32g of water to prepare a reducing agent solution for later use;

adding 161g of bottom water into a four-mouth flask, heating and stirring to 75-85 ℃, adding the oxidant solution, the reducing agent solution and the mixed monomer solution obtained in the step (I) into the four-mouth flask to react when the temperature is increased to 80-95 ℃, dropwise adding the oxidant solution, the reducing agent solution and the mixed monomer solution obtained in the step (II) into the four-mouth flask for reaction, controlling the temperature to be 80-95 ℃, dropwise adding the oxidant solution, the reducing agent solution and the mixed monomer solution obtained in the step (I) for reaction for 300min, then keeping the temperature for reaction for 30-120 min, and cooling to below 30-40;

fourthly, adjusting the pH value of the dispersant obtained in the third step to 4.0-7.0 by using liquid caustic soda (48 percent), and discharging to obtain the grinding dispersant.

Example 2:

mixing, stirring and dissolving 100g of acrylic acid, 40g of 2-acrylamide-2-methylpropanesulfonic acid, 10g of methoxy polyethylene glycol itaconic acid monoester, 5g of benzyl phenylacrylate, 1g of 1, 4-butanediol dimethacrylate and 1g of triethylene glycol dimethacrylate for later use;

dissolving 2g of ammonium persulfate into 18g of water to prepare an oxidant solution while performing the step I; dissolving 5g of sodium metabisulfite into 32g of water to prepare a reducing agent solution;

adding 161g of bottom water into a four-mouth flask, heating and stirring to 75-85 ℃, adding the oxidant solution, the reducing agent solution and the mixed monomer solution obtained in the step (I) into the four-mouth flask to react when the temperature is increased to 80-95 ℃, dropwise adding the oxidant solution, the reducing agent solution and the mixed monomer solution obtained in the step (II) into the four-mouth flask for reaction, controlling the temperature to be 80-95 ℃, dropwise adding the oxidant solution, the reducing agent solution and the mixed monomer solution obtained in the step (I) for reaction for 300min, then keeping the temperature for reaction for 30-120 min, and cooling to below 30-40;

fourthly, adjusting the pH value of the dispersant obtained in the third step to 4.0-7.0 by using liquid caustic soda (48 percent), and discharging to obtain the grinding dispersant.

Example 3

Mixing, stirring and dissolving 100g of acrylic acid, 40g of 2-acrylamide-2-methylpropanesulfonic acid, 10g of methoxy polyethylene glycol itaconic acid monoester, 5g of benzyl phenylacrylate, 1g of 1, 4-butanediol dimethacrylate and 1g of diethylene glycol dimethacrylate for later use;

dissolving 2g of ammonium persulfate into 18g of water to prepare an oxidant solution while performing the step I; dissolving 5g of sodium metabisulfite into 32g of water to prepare a reducing agent solution;

adding 161g of bottom water into a four-mouth flask, heating and stirring to 75-85 ℃, heating to 80-95 ℃, simultaneously dropwise adding an oxidant solution and a reducing agent solution, dropwise adding the mixed monomer solution obtained in the step I into the four-mouth flask to participate in reaction, controlling the temperature to be 80-95 ℃, dropwise adding the mixed monomer solution for reaction for 180-300 min, then carrying out heat preservation reaction for 30-120 min, and cooling to below 30-40 ℃ to obtain the dispersing agent;

fourthly, adjusting the pH value of the dispersant obtained in the third step to 4.0-7.0 by using liquid caustic soda (48 percent), and discharging to obtain the grinding dispersant.

Example 4: preparation of coating for papermaking coating

490g of water is added into a 2L grinding tank, stirring is started, 6g of the grinding dispersant of the embodiment 1-3 of the invention is respectively added, 1510g of 400-mesh calcium carbonate powder is added after uniform stirring, grinding dispersant of which the total mass is generally 0.1-0.2% of calcium carbonate is added for pre-dispersion, the mixture is added into a grinding machine for grinding and dispersion for 60-120 min after pre-dispersion for 10min, and the ground calcium carbonate slurry is obtained after grinding for 120min and particle size instrument test, wherein the particle size of 99% is less than 2 mu m.

The solid content of the grinding dispersant of the invention is about 39-41%, the grinding dispersant in the three examples of the invention is compared with the conventional commercially available grinding dispersant, the conventional commercially available grinding dispersant is a polycarboxylic acid system dispersant with better application effect in the current market, and the results are shown in table 1:

table 1 grind dispersant evaluation application data

As can be seen from the data measured in Table 1, the addition of 0.10% of the grinding dispersant of the present invention not only provides a good viscosity reduction and stabilization effect, but also provides a coating prepared from the grinding dispersant with a good particle size distribution ratio, and the solid content of the papermaking coating prepared from the grinding dispersant can reach 75% -76%.

In summary, the novel abrasive dispersant product of the present invention has the following advantages:

1. the production process of the product is simple, green and environment-friendly, and no waste is discharged;

2. the product adopts a polyfunctional group polymer with benzyl acrylate as a secondary chain rigid structure, the steric hindrance effect among calcium slurry particles is enhanced, and the end group of the copolymer has various strong polar groups, so that pigment particles can be better adsorbed, and a good dispersion viscosity reduction effect is achieved;

3. the product introduces a plurality of functional monomers for graft modification, so that the product has a more stable double electric layer structure, and simultaneously a novel space three-dimensional network structure can be formed around the slurry calcium particles in the grinding process of calcium carbonate, thereby improving the stability of the ground slurry calcium system and the particle size of the slurry calcium.

The above embodiments are merely illustrative of the technical concept and features of the present invention, and the present invention is not limited thereto, and any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of the present invention.