CN102675929B - Preparation method of fluorescent composite whitened attapulgite - Google Patents

Abstract

The invention discloses a method for fluorescent compound whitening attapulgite, which is characterized in that the whitening method comprises the following steps: (1) crushing attapulgite and sieving, adding water to prepare a dispersion system with a certain concentration, stirring and standing For a period of time, take the upper suspension and dehydrate it by centrifugation, and dry it at a certain temperature to obtain purified attapulgite; (2) make the purified attapulgite into a dispersion liquid, add silane coupling agent dropwise during stirring, heat for a period of time, filter, Washing, drying, grinding, and sieving to obtain modified attapulgite; (3) composite reaction of modified attapulgite with melamine-formaldehyde condensation polymer and water-soluble fluorescent whitening agent VBL to obtain fluorescent whitening attapulgite. The method improves the dispersibility of the attapulgite and the coupling effect with the resin by modifying the surface of the attapulgite with a silane coupling agent. The surface of the soil can effectively improve the fixing effect of the fluorescent whitening agent on the surface of the attapulgite, and achieve the effect of whitening the attapulgite.

Description

Fluorescence Composite Whitening Attapulgite Method

technical field

The invention relates to a method for whitening attapulgite by fluorescent compounding, in particular to a method for whitening attapulgite on the surface of modified attapulgite by compounding a fluorescent whitening agent and a polymer.

Background technique

Attapulgite is a widely used natural non-metallic mineral. It has a certain color because it contains certain impurities. The purified attapulgite is white. It has been widely used in the fields of daily chemical, polymer synthesis, papermaking, paint, etc. application. Improving the whiteness of attapulgite will help to increase the added value of attapulgite application and expand the application range of attapulgite in high-quality products.

In the fluorescent whitening of inorganic substances, the anionic fluorescent whitening agent is usually added by direct stirring method, and the anionic fluorescent whitening agent is attached to the surface of the inorganic substance through adsorption to form a compound. It is generally difficult for inorganic substances to achieve the ideal whitening effect. Simple mixing and adsorption cannot make the whitening agent and inorganic substances evenly distributed, especially the application in clay inorganic minerals is greatly affected by the clay structure and surface properties.

In order to achieve the purpose of effectively whitening the attapulgite, it is the key to solve the problem to effectively fix the fluorescent whitening agent and the polymer on the surface of the attapulgite, and to strengthen the strength of the fluorescent whitening agent. 

The surface of attapulgite is hydrophilic and suitable for use in polar systems. However, it is difficult to disperse in non-polar organic substances and polymers. For this reason, it is necessary to carry out organic modification on its surface (non-metal mine, 2007,30(6):1~4).

Chinese patent application (publication number CN 1882626A) discloses a preparation method of fluorescent whitening pigments. The whitening pigments are obtained by polymerization of melamine-formaldehyde condensation products and fluorescent whitening agents, which have excellent performance in papermaking processes.

Contents of the invention

The object of the present invention is to provide a fluorescent compound whitening method for attapulgite, which uses chemical modification to compound and whiten attapulgite to increase the added value of attapulgite.

The technical solution of the present invention is that the whitening method includes the following steps: (1) crush the attapulgite and pass it through a 200-mesh sieve, add water to form a dispersion system with a certain concentration, stir, let it stand for a period of time, and take the upper layer of suspension for centrifugal dehydration , dried at a certain temperature to obtain purified attapulgite; (2) Prepare the purified attapulgite into a dispersion liquid, add coupling agent dropwise during stirring, and heat for a period of time to react, filter, wash, dry, grind, and sieve to obtain Modified attapulgite; (3) Compound reaction of modified attapulgite with melamine-formaldehyde condensation polymer and water-soluble fluorescent whitening agent to prepare whitening attapulgite.

Wherein, the concrete steps of this whitening method are as follows:

(1) Purification of attapulgite: select attapulgite, pass through a 200-mesh sieve after crushing, add water to form a dispersion system with a mass concentration of 6%, stir for 1 hour, let stand for 6 hours, take the upper suspension and dehydrate it by centrifugation at 200~ Dry at 400°C to obtain purified attapulgite, and the whiteness of the purified attapulgite is above 75.0%;

(2) Attapulgite modification: make the purified attapulgite into a dispersion with a content of 50g/L~100g/L, add a coupling agent of 5%~10% of the dry attapulgite mass dropwise while stirring, and heat to 60°C~ React at 80°C for 3~5 hours, filter and wash 6 times to remove unreacted coupling agent, dry in an oven at 60°C~80°C for 3~5 hours, grind through a 325 mesh sieve to obtain coupling agent modified attapulgite ;

(3) Composite reaction: Add 3-8% fluorescent whitening agent by mass to 60% pentahydroxy-melamine, add water and stir evenly until the fluorescent whitening agent is completely dissolved, adjust the pH value to 3.5~ with concentrated hydrochloric acid 4.5, add modified attapulgite with 50-70% of the above mixture and stir evenly, heat to 70-90°C, continue to add hydrochloric acid to adjust the pH value to 1.5-2.5, stir and react at 70-90°C for 4-5 hours, cool to After room temperature, use sodium hydroxide to adjust the pH value to 9.0-10.0 for alkalization, and perform ball milling for 1-2 hours, centrifugally wash, then vacuum-dry at 60-80°C, and grind through a 325-mesh sieve to obtain fluorescent composite whitening attapulgite. the

Wherein, the coupling agent is an aminosilane coupling agent.

The beneficial effects of the present invention are:

1. The surface of attapulgite is modified by silane coupling agent, which improves the dispersion of attapulgite and the coupling effect with resin. The complex obtained by the reaction of melamine-formaldehyde resin and fluorescent whitening agent is compounded on attapulgite through coupling Surface, thereby effectively improving the fixing effect of the fluorescent whitening agent on the surface of the attapulgite, and achieving the effect of whitening the attapulgite.

2. Utilize cheap attapulgite resources and prepare whitening attapulgite through the method of fluorescent compounding, which improves the added value of attapulgite resource utilization.

Detailed ways

The present invention will be further described in detail below in conjunction with specific embodiments. These examples are not to be understood as limitations on technical solutions.

Example 1

(1) Purification of attapulgite: take attapulgite, pass through a 200-mesh sieve after crushing, add water to make a dispersion system with a mass concentration of 6%, stir for 1 hour, let stand for 6 hours, take the upper suspension and dehydrate it by centrifugation at 200°C Dry to obtain purified attapulgite with a whiteness of 75.0%;

(2) Attapulgite modification: take 30g of purified attapulgite and add 500mL of deionized water to make a dispersion liquid, add 3g of silane coupling agent KH-550 dropwise while stirring, heat to 80°C for 4 hours, filter and wash 6 times to wash off The unreacted coupling agent was dried in an oven at 70°C for 4 hours, and ground through a 325-mesh sieve to obtain a coupling agent-modified attapulgite;

(3) Composite reaction: take 30g of 60% pentahydroxy-melamine, add 0.9g of fluorescent whitening agent VBL, add 100mL of water and stir until the fluorescent whitening agent is completely dissolved, adjust the pH value to 4.0 with concentrated hydrochloric acid, and add 21g at the same time Stir the modified attapulgite evenly, heat to 70°C, continue to add hydrochloric acid to adjust the pH value to 2.0, stir and react at 70°C for 5 hours, after cooling to room temperature, adjust the pH value to 9 with sodium hydroxide solution for alkalization, and perform ball milling After 1.5 hours, centrifuge and wash with water, then vacuum-dry at 70°C and grind through a 325-mesh sieve to obtain fluorescent composite whitening attapulgite. The whiteness is 88.7%.

Example 2

(1) Purification of attapulgite: take attapulgite, pass through a 200-mesh sieve after being crushed, add water to make a dispersion system with a mass concentration of 6%, stir for 1 hour, let it stand for 6 hours, take the upper suspension and dehydrate it by centrifugation at 300°C Dry to obtain purified attapulgite with a whiteness of 78.0%;

(2) Attapulgite modification: Take 30g of purified attapulgite and add it to 500mL deionized water to make a dispersion, add 1.5g of silane coupling agent KH-550 dropwise while stirring, heat to 60°C for 5 hours, filter and wash 6 times Remove the unreacted coupling agent, dry it in an oven at 80°C for 3 hours, and grind it through a 325-mesh sieve to obtain a coupling agent-modified attapulgite;

(3) Composite reaction: take 30g of 60% pentahydroxy-melamine, add 1.8g of fluorescent whitening agent VBL, add 100mL of water and stir until the fluorescent whitening agent is completely dissolved, adjust the pH value to 3.5 with concentrated hydrochloric acid, and add 16g at the same time Stir the modified attapulgite evenly, heat to 80°C, continue to add hydrochloric acid to adjust the pH value to 2.5, stir and react at 80°C for 4 hours, after cooling to room temperature, adjust the pH value to 10.0 with sodium hydroxide solution for alkalization, and perform ball milling After 1 hour, centrifuge and wash with water, vacuum-dry at 60°C, and grind through a 325-mesh sieve to obtain fluorescent composite whitening attapulgite. The whiteness is 92.5%.

Example 3

(1) Purification of attapulgite: Take attapulgite, pass through a 200-mesh sieve after being crushed, add water to make a dispersion system with a mass concentration of 6%, stir for 1 hour, let it stand for 6 hours, take the upper suspension and dehydrate it by centrifugation at 400°C Dry to obtain purified attapulgite with a whiteness of 80.0%;

(2) Attapulgite modification: Take 30g of purified attapulgite and add it to 500mL deionized water to make a dispersion, add 2.3g of silane coupling agent KH-550 dropwise while stirring, heat to 70°C for 3 hours, filter and wash 6 times Remove the unreacted coupling agent, dry it in an oven at 60°C for 5 hours, and grind it through a 325-mesh sieve to obtain a coupling agent-modified attapulgite;

(3) Composite reaction: Take 30g of 60% pentahydroxy-melamine, add 2.0g of fluorescent whitening agent VBL, add 100mL of water and stir evenly until the fluorescent whitening agent is completely dissolved, adjust the pH value to 4.5 with concentrated hydrochloric acid, and add 16g at the same time Stir the modified attapulgite evenly, heat to 90°C, continue to add hydrochloric acid to adjust the pH value to 1.5, stir and react at 90°C for 4.5 hours, after cooling to room temperature, adjust the pH value to 10.0 with sodium hydroxide solution for alkalization, and perform ball milling After 2 hours, centrifuge and wash with water, vacuum-dry at 80°C, and grind through a 325-mesh sieve to obtain fluorescent composite whitening attapulgite. The whiteness is 93.9%.

Example 4

(1) Attapulgite purification: with embodiment 3;

(2) Attapulgite modification: Take 30 g of purified attapulgite and add it to 500 mL of deionized water to make a dispersion, add 3 g of silane coupling agent KH-792 dropwise while stirring, and the rest of the steps are the same as in Example 1;

(3) Compound reaction: take 30g of 60% pentahydroxy-melamine, add 2.4g of fluorescent whitening agent VBL, add 100mL of water and stir until the fluorescent whitening agent is completely dissolved, adjust the pH value to 4.1 with concentrated hydrochloric acid, and add 16g at the same time Stir the modified attapulgite evenly, heat to 75°C, continue to add hydrochloric acid to adjust the pH value to 2.2, stir and react at 75°C for 5 hours, after cooling to room temperature, adjust the pH value to 9 with sodium hydroxide solution for alkalization, and perform ball milling After 1.5 hours, centrifuge and wash with water, then vacuum-dry at 75°C and grind through a 325-mesh sieve to obtain fluorescent composite whitening attapulgite. The whiteness is 96.2%.

Claims (3)

1. The method for fluorescent compound whitening attapulgite is characterized in that the whitening method comprises the following steps: (1) crushing attapulgite and sieving, adding water to form a dispersion system with a certain concentration, stirring, standing for a period of time, taking The upper layer suspension is centrifugally dehydrated, and then dried at a certain temperature to obtain purified attapulgite; (2) Prepare the purified attapulgite into a dispersion, add silane coupling agent dropwise during stirring, heat for a period of time, filter, wash, and dry , grinding, and sieving to obtain modified attapulgite; (3) composite reaction of modified attapulgite with melamine-formaldehyde condensation polymer and water-soluble fluorescent whitening agent VBL to obtain fluorescent whitening attapulgite. 2. the method for fluorescent compound whitening attapulgite according to claim 1, is characterized in that the concrete steps of this whitening method are as follows: (1) Purification of attapulgite: select attapulgite, pass through a 200-mesh sieve after being crushed, add water to form a dispersion system with a mass concentration of 6%, stir for 1 hour, let stand for 6 hours, take the upper suspension and dehydrate it by centrifugation, and then 200~ Dry at 400°C to obtain purified attapulgite, and the whiteness of the purified attapulgite is more than 75%; (2) Attapulgite modification: make the purified attapulgite into a dispersion with a content of 50g/L~100g/L, add a silane coupling agent of 5%~10% of the dry attapulgite mass dropwise while stirring, and heat to 60°C React at ~80°C for 3~5 hours, filter and wash 5~7 times to remove unreacted silane coupling agent, dry in an oven at 50°C~80°C for 3~5 hours, grind through a 325 mesh sieve to obtain silane coupling agent modified attapulgite; (3) Composite reaction: Add 3~8% of the fluorescent whitening agent VBL to the 60% pentahydroxy-melamine, add water and stir evenly until the fluorescent whitening agent VBL is completely dissolved, and adjust the pH value with concentrated hydrochloric acid 3.5~4.5, add the modified attapulgite with 50~70% of the above mixture, stir evenly, heat to 60~90°C, continue to add hydrochloric acid to adjust the acidity pH value to 1.5~2.5, stir and react at 60~90°C for 4~5 hours, After cooling to room temperature, use sodium hydroxide to adjust the pH value to 9.0~10.0 for alkalization, and perform ball milling for 1~2 hours, centrifuge and wash, then vacuum dry at 60~80°C, grind through a 325 mesh sieve, and obtain fluorescent composite whitening concave earth. 3. The method for fluorescent composite whitening attapulgite according to claim 1 or 2, characterized in that: the silane coupling agent is an aminosilane coupling agent.