CN113773672A

CN113773672A - White pearlescent pigment and preparation method and application thereof

Info

Publication number: CN113773672A
Application number: CN202111167714.8A
Authority: CN
Inventors: 费明; 林幼贞; 林学周; 谢秉昆
Original assignee: Fujian Kuncai Material Technology Co ltd
Current assignee: Fujian Kuncai Material Technology Co ltd
Priority date: 2021-09-30
Filing date: 2021-09-30
Publication date: 2021-12-10

Abstract

The invention relates to the technical field of pigments. Discloses a white pearlescent pigment and a preparation method and application thereof, which comprises the following steps: coating a composite layer: loading titanium dioxide and titanium phosphate on the surface of base material particles by adopting a liquid phase deposition method to form a composite layer to obtain a primary pigment; and (3) calcining: calcining the primary pigment to obtain the white pearlescent pigment with the surface loaded with the titanium dioxide doped titanium phosphate composite layer. The white pearlescent pigment is prepared by the preparation method provided by the application. Phosphate radicals on the surfaces of the particles in the high-temperature calcination process can effectively inhibit the titanium dioxide particles from growing in a disordered manner, so that the titanium dioxide can uniformly form a compact layer, and the glossiness is improved. The white pearlescent pigment provided by the application has excellent color saturation and brightness. The pigment can be applied to the fields of cosmetics, coatings, paints, plastics, leather, wallpaper and the like.

Description

White pearlescent pigment and preparation method and application thereof

Technical Field

The invention relates to the technical field of pigments, in particular to a white pearlescent pigment and a preparation method and application thereof.

Background

The white effect pigments are roughly classified into two types, one is a flaky aluminum pigment which is opaque and has high covering power and metallic luster, but has the characteristic of not being acid-base-resistant and limits the application field; secondly, the pearlescent effect pigment of titanium dioxide coated by the flaky substrate has a certain metallic luster effect and a certain covering power which can not reach the metallic luster and the covering power of the flaky aluminum pigment, but has better chemical stability, environmental protection safety and wide application field, and has part of markets for gradually replacing the flaky aluminum pigment. Therefore, with the market demand, the development and research of white effect pigments with high hiding power and high gloss is a necessary trend.

In view of this, the invention is particularly proposed.

Disclosure of Invention

The object of the present invention is to provide a white pearlescent pigment and a process for the preparation thereof, which aim to ameliorate at least one of the problems mentioned in the background.

The invention is realized by the following steps:

in a first aspect, the present invention provides a method for preparing a white pearlescent pigment, comprising:

coating a composite layer: loading titanium dioxide and titanium phosphate on the surface of base material particles by adopting a liquid phase deposition method to form a composite layer to obtain a primary pigment;

and (3) calcining: and calcining the primary pigment to obtain the white pearlescent pigment with the surface loaded with the titanium dioxide doped titanium phosphate composite layer.

In an alternative embodiment, the composite layer cladding is: adding titanium oxychloride, alkali and phosphate radical ions into the solution in which the base material particles are dispersed, so that titanium dioxide and titanium phosphate generated by reaction are loaded on the surfaces of the base material particles;

preferably, in the process of coating the composite layer, the temperature of the reaction system is controlled to be 75-85 ℃, and the pH value is 1.5-2.0.

In an alternative embodiment, the mass ratio of the titanium dioxide content in the composite layer to the base material is 40-60%.

In an optional embodiment, the mass ratio of the titanium phosphate content in the composite layer to the titanium dioxide is 0.5 to 1.5%.

In alternative embodiments, the substrate is a sheet substrate;

preferably, the platy substrate is at least one of synthetic mica and alumina;

preferably, the flaky base material is synthetic mica with the particle size of 5-100 mu m; more preferably 10 to 40 μm.

In an alternative embodiment, before the step of cladding the composite layer, the method further comprises:

pre-coating: coating a titanium phosphate layer on the surface of the substrate particles;

preferably, after the titanium phosphate layer is calcined, the mass of the titanium phosphate layer accounts for 1-3% of the mass of the base material.

In an alternative embodiment, the titanium phosphate is coated by: adding titanium oxychloride and phosphate into the solution in which the base material particles are dispersed, and enabling the titanium phosphate generated by the reaction to be loaded on the surfaces of the base material particles;

preferably, when the titanium phosphate is coated to form the pretreatment layer, the temperature of the reaction system is controlled to be 55-78 ℃, and the pH value is controlled to be 0.5-1.0;

preferably, the phosphate is one or more of sodium phosphate, sodium dihydrogen phosphate, sodium polyphosphate and sodium hexametaphosphate.

In an optional embodiment, the calcination temperature is 800-1000 ℃, and the calcination time is 25-40 min;

preferably, the drying is carried out at the temperature of 100-120 ℃ for 10-14 h.

In an alternative embodiment, the pH is controlled with a basic solution, and the phosphate is added to the solution together with the basic solution;

preferably, the alkali solution is a sodium hydroxide solution.

In a second aspect, the present invention provides a white pearlescent pigment prepared by the preparation method according to any one of the preceding embodiments.

In a third aspect, the present invention provides the use of a white pearlescent pigment in cosmetics, coatings, paints, plastics, leather or wallpaper.

The invention has the following beneficial effects:

by loading uniformly dispersed titanium dioxide and titanium phosphate on the surface of the base material particles, phosphate radicals on the surface of the particles can effectively inhibit the titanium dioxide particles from growing in a disordered manner in the high-temperature calcination process, so that the titanium dioxide can uniformly form a compact layer, and the glossiness is improved. Moreover, the titanium phosphate doped in the composite layer obtained after sintering can also increase the opacity of the flaky substrate, and has the effects of increasing the covering power of the pearlescent pigment and the reflection effect of light.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

FIG. 1 is a schematic representation of a product made by application example 1;

FIG. 2 is a schematic diagram of a product obtained in application example 2.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

The following specifically describes the white pearlescent pigment provided by the embodiment of the invention, and the preparation method and application thereof.

The implementation of the invention provides a preparation method of a white pearlescent pigment, which comprises the following steps:

By loading uniformly dispersed titanium dioxide and titanium phosphate on the surface of the base material particles, phosphate radicals on the surface of the particles can effectively inhibit the titanium dioxide particles from growing in a disordered manner in the high-temperature calcination process, so that the titanium dioxide can uniformly form a compact layer, and the glossiness is improved. Moreover, the titanium phosphate doped in the composite layer obtained after sintering can also increase the opacity of the flaky substrate, and has the effects of increasing the covering power of the pearlescent pigment and the reflection effect of light. The preparation method specifically comprises the following steps:

s1, pre-coating: coating titanium phosphate on the surface of the base material particles.

The method specifically comprises the following steps: adding titanium oxychloride and phosphate into the solution in which the base material particles are dispersed, and enabling the titanium phosphate generated by the reaction to be loaded on the surfaces of the base material particles;

more specifically: suspending the flaky base material in water, controlling the system temperature to be 55-78 ℃ (such as 55 ℃, 60 ℃, 70 ℃ or 78 ℃), and adjusting the pH of the system to be 0.5-1.0 by using a hydrochloric acid solution. And then slowly adding titanium oxychloride into the solution system, adding phosphate into the solution system to enable the titanium oxychloride and the phosphate to completely react and keep the pH value within the range of 0.5-1.0, wherein the adding amount of the titanium oxychloride is calculated by that the mass of the calcined titanium oxychloride accounts for 1-3% (such as 1%, 2% or 3%) of the mass of the base material, and after the titanium oxychloride is added, continuing stirring for half an hour to ensure that the reaction is completely carried out and the titanium oxychloride completely coats the surface of the base material.

The titanium phosphate pretreatment layer is coated on the surface of the base material, so that the opacity of the flaky base material can be increased.

Preferably, the phosphate is one or more of sodium phosphate, sodium dihydrogen phosphate, sodium polyphosphate and sodium hexametaphosphate, preferably sodium phosphate.

Preferably, the platelet-shaped substrate is at least one of synthetic mica and alumina.

S2, coating by a composite layer: loading titanium dioxide and titanium phosphate dispersed in the solution on the surface of base material particles to obtain a primary pigment;

the method comprises the following steps: adding titanium oxychloride, alkali and phosphate radical ions into the solution in which the base material particles are dispersed, so that titanium dioxide and titanium phosphate generated by the reaction are loaded on the surfaces of the base material particles.

More specifically: and (2) raising the temperature of the solution system in the step S1 to 75-85 ℃ (for example, 75 ℃, 80 ℃ or 85 ℃), adjusting the pH to 1.5-2.0 by adopting an alkali solution, then slowly and continuously adding the titanium oxychloride solution into the solution system, in the process, simultaneously adding the alkali solution to keep the pH of the system within the range of 1.5-2.0, and simultaneously adding a small amount of phosphate radical in the process of adding the alkali to enable the phosphate radical and the titanium oxychloride to react to generate a small amount of titanium phosphate. In this process, the amount of titanium oxychloride added is 40 to 60% (e.g., 40%, 50% or 60%) by mass of the calcined titanium dioxide to the base material, and the amount of phosphate is 0.5 to 1.5% (e.g., 0.5%, 1% or 1.5%) by mass of the calcined titanium phosphate to the titanium dioxide. And after the reaction is finished, filtering and washing to obtain a primary pigment.

Preferably, the process of adding the alkali and simultaneously adding a small amount of phosphate is as follows: adding an alkali solution containing phosphate radical.

Preferably, the base in this application is sodium hydroxide.

S3, calcining: and drying the primary pigment, and calcining at 800-1000 ℃ to obtain the white pearlescent pigment with the surface loaded with the titanium dioxide doped titanium phosphate composite layer.

The method comprises the following steps: and (3) drying the washed primary pigment for 10-14 h (for example, 10h, 12h or 14h) at 100-120 ℃ (for example, 100 ℃, 110 ℃ or 120 ℃). After drying, calcining the obtained product at 800-1000 ℃, such as 800 ℃, 900 ℃ or 1000 ℃ for 25-40 min (such as 25min, 30min, 35min or 40min) to obtain the white pearlescent pigment.

The white pearlescent pigment provided by the embodiment of the application is prepared by the preparation method provided by the embodiment of the application. The particles of the titanium phosphate composite material are a base material, a titanium phosphate pretreatment layer and a titanium dioxide doped titanium phosphate composite layer from inside to outside.

The features and properties of the present invention are described in further detail below with reference to examples. The mass concentration of titanium oxychloride used in the specific examples was 160g/L in terms of titanium dioxide which could be produced by the reaction, and it was obtained by hydrochloric acid extraction.

Example 1

The application provides a white pearlescent pigment and a preparation method thereof.

Adding 100g of synthetic mica with a particle size range of 5-45 μm (average particle size of 27 μm) into 2L of soft water under stirring, heating the system to 65 ℃, reducing the pH value to 0.5 by hydrochloric acid with the ratio of 1:1, continuously and slowly adding titanium oxychloride with the generated titanium phosphate accounting for 1.5 percent of the mass of the synthesized mica, adding a sodium phosphate solution with the mass concentration of 5 percent into the solution system to react with the titanium oxychloride, and the constant pH value of the solution system is kept unchanged by the added sodium phosphate solution, the solution is continuously stirred for half an hour after the addition is finished, then heating to 78 ℃, increasing the pH value to 1.5, continuously and slowly adding 250ml of titanium oxychloride solution, reacting the mixed solution containing phosphate ions and the sodium hydroxide solution with the mass concentration of 30% with the titanium oxychloride, keeping the constant pH value, the proportion of the total amount of phosphate radicals to the total amount of hydroxyl radicals in the mixed solution was 1.5% as the mass ratio of the produced titanium phosphate to titanium dioxide. After the reaction, the mixture was filtered, washed, dried at 110 ℃ for 12 hours, and calcined at 800 ℃ for 0.5 hour. A white pearlescent pigment is obtained.

The mass ratio of the pretreatment layer to the synthetic mica of the prepared white pearlescent pigment is 1.5%, the mass ratio of the titanium dioxide to the synthetic mica in the composite layer is 94.6%, and the mass ratio of the titanium phosphate to the titanium dioxide in the composite layer is 1.5%.

Example 2

This embodiment is substantially the same as embodiment 1 except that: the particle size range of the synthetic mica was selected to be 10 to 30 μm (average particle size of 15 μm).

Example 3

This embodiment is substantially the same as embodiment 1 except that: after the reaction is finished, in the calcined white pearlescent pigment, the mass ratio of the titanium phosphate to the titanium dioxide in the composite layer is 0.5%.

Example 4

This embodiment is substantially the same as embodiment 1 except that: after the reaction is finished, in the calcined white pearlescent pigment, the mass ratio of the titanium phosphate to the titanium dioxide in the composite layer is 1%.

Example 5

This embodiment is substantially the same as embodiment 1 except that: after the reaction, the mass ratio of titanium dioxide to synthetic mica in the white pearlescent pigment obtained by calcination was 50%.

Example 6

This embodiment is substantially the same as embodiment 1 except that: after the reaction, the mass ratio of titanium dioxide to synthetic mica in the white pearlescent pigment obtained by calcination was 60%.

Example 7

This example is substantially the same as example 1 except that the uncoated titanium phosphate pretreatment layer was directly clad with a composite layer.

Comparative example 1

This comparative example is essentially the same as example 1 except that during the slow addition of 250ml of the titanyl dichloride solution, the pH was adjusted and reacted completely with the titanyl dichloride using a sodium hydroxide solution which did not contain phosphate ions.

The second layer of white pearlescent pigment containing no titanium phosphate is prepared.

Comparative example 2

This comparative example is essentially the same as example 7 except that during the slow addition of 250ml of the titanyl dichloride solution, the pH was adjusted and reacted completely with the titanyl dichloride using a sodium hydroxide solution that did not contain phosphate ions.

Examples of the experiments

The white pearlescent pigments of examples 1 to 7 and comparative examples 1 to 2 were subjected to performance evaluation in a specific manner of:

the quality of the sample is evaluated by a common method of coating a scratch card or a spray plate. Adding a certain pearlescent pigment into resin or paint, stirring uniformly, coating or spraying a plate, and testing the color and the smoothness by using an X-Rite MA68 color difference instrument. As shown in the following table:

TABLE 1 Alice test color data

In the table, h ° represents hue, C x represents saturation, L x represents brightness a represents red and green; b represents yellow and blue.

As can be seen from the above table, the white pearlescent pigment provided in the examples of the present application has very good saturation and brightness. Comparing example 1 with example 7, the gloss and hiding power are slightly inferior to example 1, and it can be illustrated that the pre-treatment layer is coated in advance to improve the opacity and gloss of the pigment. Comparing example 1 with comparative example 1 and example 7 with comparative example 2, it can be seen that the pigment of example 1 is significantly better in gloss and saturation than comparative example 1, and the pigment of example 7 is significantly better in gloss and saturation than comparative example 2, thus it can be illustrated that the gloss and saturation of the pigment can be significantly improved by doping titanium phosphate into the composite layer during the preparation process, and thus it can be illustrated that the doping of titanium phosphate can improve the hiding power and thus the saturation can be improved.

Experimental example 2

Application example 1: taking paint spraying as an example

Accurately weigh 4.00 grams of the pearlescent pigment of example 1, add 4.0 grams of butyl acetate and 8.0 grams of polyester automotive coating resin, place under a stirrer and stir for 10 minutes, continue to add 84.0 grams of the automotive coating resin system and stir for 5 minutes. The viscosity of the coating was adjusted to Ford4 cup number 14-15 seconds before spraying. And during spraying, the temperature of a spraying room is controlled to be 25 ℃, and the relative humidity is controlled to be 60%. Spraying twice, flashing for 10 minutes, covering with varnish, flashing again, and baking at 140 ℃ for 30 minutes. The painting results are shown in fig. 1, and it can be seen that they have very excellent color and color effects.

Application example 2: taking injection molding applications as an example:

200 g of polypropylene (PP) material dried at 105 ℃ is accurately weighed into a plastic sealing bag, 1 ml of gloss oil (also called dispersing oil) is added, and then the mixture is shaken to fully mix the gloss oil and the polypropylene material. 4.000 g of the pearl essence of example 1 was weighed into a plastic sealed bag by using an analytical balance preparation, and the bag was shaken and kneaded again to sufficiently and uniformly disperse the pearl essence in the PP particles. After the temperature of the charging barrel reaches a set value (usually 180-200 ℃), adding the prepared polypropylene material into a hopper, extruding the original residual material in the charging barrel by using the functions of injecting glue and melting glue until a new material is extruded, wherein the extruded new material has luster, no impurities, no black spots, no scorching and no bubbles; meanwhile, the nozzle is not blocked during glue injection. After the front and the rear plastic sheets are not different, the produced plastic sheets are stable and qualified products, and can enter automatic normal production. As shown in fig. 2, the plastic sheet produced had very excellent color and color effects.

In summary, according to the preparation method provided by the embodiment of the present application, the uniformly dispersed titanium dioxide and titanium phosphate are loaded on the surface of the substrate particle, so that the phosphate radical on the surface of the particle can effectively inhibit the titanium dioxide particle from growing in an unordered manner in the high-temperature calcination process, the titanium dioxide can uniformly form a dense layer, and the glossiness is improved. Moreover, the titanium phosphate doped in the composite layer obtained after sintering can also increase the opacity of the flaky substrate, and has the effects of increasing the covering power of the pearlescent pigment and the reflection effect of light. Therefore, the white pearlescent pigment prepared by the method provided by the application has excellent performance. The pigment can be applied to the fields of cosmetics, coatings, paints, plastics, leather, wallpaper and the like.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a white pearlescent pigment, which is characterized by comprising the following steps:

2. The method for preparing a white pearlescent pigment according to claim 1, wherein the composite layer coating is: adding titanium oxychloride, alkali and phosphate radical ions into the solution in which the base material particles are dispersed, so that titanium dioxide and titanium phosphate generated by reaction are loaded on the surfaces of the base material particles;

preferably, in the process of coating the composite layer, the temperature of a reaction system is controlled to be 75-85 ℃, and the pH value is 1.5-2.0;

preferably, the mass ratio of the titanium dioxide content in the composite layer to the base material is 40-60%.

3. The method for preparing a white pearlescent pigment according to claim 2, characterized in that the pH is controlled by an alkali solution, and the phosphate ions are added to the solution together with the alkali solution;

preferably, the alkali solution is a sodium hydroxide solution.

4. The method for producing a white pearlescent pigment according to any one of claims 1 to 3, wherein the mass ratio of the titanium phosphate content in the composite layer to the titanium dioxide is 0.5 to 1.5%.

5. The method for producing a white pearlescent pigment according to claim 1, characterized in that the substrate is a flaky substrate;

preferably, the platy substrate is at least one of synthetic mica and alumina;

6. The method for preparing a white pearlescent pigment according to claim 1, further comprising, before the step of coating the composite layer:

7. The method for preparing a white pearlescent pigment according to claim 6, wherein the coating manner of the titanium phosphate is as follows: adding titanium oxychloride and phosphate into the solution in which the base material particles are dispersed, and enabling the titanium phosphate generated by the reaction to be loaded on the surfaces of the base material particles;

8. The method for preparing a white pearlescent pigment according to claim 1, wherein the calcination temperature is 800 to 1000 ℃ and the calcination time is 25 to 40 min;

9. A white pearlescent pigment, which is produced by the production process according to any one of claims 1 to 8.

10. Use of the white pearlescent pigment of claim 9 in cosmetics, coatings, paints, plastics, leather or wallpaper.