CN110967308A

CN110967308A - Method for testing the temperature resistance of titanium dioxide

Info

Publication number: CN110967308A
Application number: CN201911172471.XA
Authority: CN
Inventors: 徐庭敏; 柯良辉; 周俊; 和柳
Original assignee: Chongqing Titanium Industry Co Ltd
Current assignee: Chongqing Titanium Industry Co Ltd
Priority date: 2019-11-26
Filing date: 2019-11-26
Publication date: 2020-04-07

Abstract

The invention belongs to the technical field of titanium dioxide application performance testing, and particularly relates to a method for testing the temperature resistance of titanium dioxide. The technical problem to be solved by the present invention is to provide an accurate and simple method for detecting the temperature resistance of titanium dioxide. The method is: a. uniformly mixing titanium dioxide and polypropylene resin to obtain a mixture; b. taking the mixture and injecting it into a PP head material sample at different temperatures and pressures, and then taking the mixture for injection molding again after maintaining a constant temperature on the basis of the different temperatures Make a PP constant temperature sample; c. Use a spectrophotometer to measure the L, a, b values of the PP head sample sample and the PP constant temperature sample in step b, and calculate the Hunter whiteness and color difference ΔE. By adopting the method of the invention, the accuracy of the determination result can be ensured more intuitively and precisely.

Description

Method for detecting temperature resistance of titanium dioxide

Technical Field

The invention belongs to the technical field of titanium dioxide application performance detection, and particularly relates to a method for detecting the temperature resistance of titanium dioxide.

Background

Titanium dioxide is a white inorganic pigment, has stable chemical properties, is considered to be a white pigment with better performance in the world at present, and is widely applied to the industries of coating, plastics, paper making and the like. The temperature resistance of titanium dioxide is different due to different production processes, and the difference directly influences the temperature resistance and yellowing resistance of titanium dioxide products.

At present, most of the detection of the temperature resistance of titanium dioxide is to directly calcine a titanium dioxide product at high temperature and then measure the whiteness value of the titanium dioxide product to perform temperature resistance and yellowing resistance tests and evaluation. Tests show that the titanium dioxide subjected to high-temperature calcination has the phenomenon of large surface-to-surface color difference due to uneven heating, the temperature resistance and yellowing resistance of the titanium dioxide cannot be truly represented, and the accuracy and authenticity of the titanium dioxide detection result are seriously affected. It is extremely necessary to research an accurate and simple detection method for evaluating the temperature resistance of titanium dioxide in a plastic application system.

Disclosure of Invention

The invention aims to solve the technical problem of providing an accurate, simple and convenient method for detecting the temperature resistance of titanium dioxide.

The invention provides a method for detecting the temperature resistance of titanium dioxide, which is used for solving the technical problem. The method comprises the following steps:

a. uniformly mixing titanium dioxide and polypropylene resin to obtain a mixture;

b. taking the mixture, performing injection molding on the mixture at different temperatures and pressures to form a PP head material sample plate, keeping the temperature constant on the basis of the different temperatures, and then performing injection molding on the mixture again to form a PP constant-temperature sample plate;

c. and (4) measuring the L, a and b values of the PP head stock sample plate and the PP constant temperature sample plate in the step b by using a spectrocolorimeter, and calculating the Hunter whiteness and the color difference △ E.

In the method for detecting the temperature resistance of the titanium dioxide, in the step a, the addition amount of the titanium dioxide is 0.2-0.6 wt% of the polypropylene resin.

In the method for detecting the temperature resistance of the titanium dioxide, in the step b, the mixture is respectively injected and molded into a PP head material sample plate at 200 ℃, 280 ℃, 300 ℃ and 320 ℃; and (3) carrying out constant temperature injection molding on the mixture at 200 ℃, 280 ℃, 300 ℃ and 320 ℃ for 5-15 min respectively to obtain a PP constant temperature sample plate.

Further, in the step b, the pressure value corresponding to 200 ℃ is 80 or 85 bar; the pressure value corresponding to 280 ℃ is 50 or 55 bar; the pressure value corresponding to 300 ℃ is 45 or 50 bar; the pressure value corresponding to 320 ℃ is 40 or 45 bar.

In the method for detecting the temperature resistance of the titanium dioxide, in the step c, the whiteness value is an average value detected for 3-5 times.

The invention has the beneficial effects that: according to the invention, the whiteness is detected under different temperature conditions by adopting the fusion of the polypropylene resin (PP) and the titanium dioxide, and the temperature resistance of the titanium dioxide is evaluated through the whiteness and the color difference value, so that the accuracy of a measurement result is ensured more intuitively and accurately, and the technical problem that the measurement result is inaccurate due to the fact that the titanium dioxide after high-temperature calcination is easily heated unevenly is solved. The method is simple and convenient to operate and has a good application prospect.

Drawings

FIG. 1 is a graph showing changes in Hunter whiteness values of samples measured according to an embodiment of the present invention.

FIG. 2 is a graph showing the change in color difference (△ E) of a sample measured according to an embodiment of the present invention.

Detailed Description

Specifically, the invention provides a method for detecting the temperature resistance of titanium dioxide. The method comprises the following steps:

In the step a, the polypropylene resin (PP) and the titanium dioxide are fused, the compatibility of the PP and the titanium dioxide is good, and the defect that the titanium dioxide is heated unevenly because the titanium dioxide is directly calcined at high temperature is overcome. The polypropylene resin used in the present invention is T30S.

In the step b of the invention, because the melting state of the mixture of titanium dioxide and polypropylene resin is slightly changed under different temperature conditions, if the pressure is kept unchanged, the phenomenon of flash or unfilled corner can be generated when the sample plate is formed by injection molding, and therefore, the pressure is required to be adjusted under different temperature conditions. When the temperature is 200 ℃, the corresponding pressure value is 80 or 85 bar; when the temperature is 280 ℃, the corresponding pressure value is 50 or 55 bar; when the temperature is 300 ℃, the corresponding pressure value is 45 or 50 bar; at a temperature of 320 c, the corresponding pressure value is 40 or 45 bar. And selecting a proper pressure value according to the actual condition of the operation process.

In the step c, a spectrocolorimeter is adopted to respectively measure the values of L, a and b at 200 ℃, 200 ℃ and 280 ℃, 280 ℃ and 280 ℃ for 5-15 min, 300 ℃ and 5-15 min, 320 ℃ and 320 ℃ for 5-15 min, a flat and uniform sample plate is selected during measurement, the values of L, a and b at 3-5 points on the sample plate are respectively detected, and an average value is obtained.

The Hunter whiteness is calculated according to the formula:

and (4) calculating.

The color difference △ E is calculated according to the formula:

and (4) calculating.

The temperature resistance of the titanium dioxide is evaluated according to the whiteness value and the color difference △ E, wherein the smaller the △ E is, the better the temperature resistance and yellowing resistance is, and the worse the temperature resistance and yellowing resistance is.

The present invention will be further illustrated by the following specific examples.

The experimental equipment adopted by the invention is as follows: electronic balance (accuracy 0.01), electronic balance (accuracy 0.0001), SA600/150 injection molding machine, CM-5 spectrocolorimeter.

Example 1

Weighing 2.4g of titanium dioxide sample No. 1, pouring into a plastic bag filled with 600.00g of PP resin, uniformly mixing by hand shaking, carrying out injection molding on the uniformly mixed sample at the temperature of 200 ℃ and the pressure of 85bar to obtain a PP head material sample, carrying out injection molding on the mixture at the constant temperature of 200 ℃ for 5min to obtain a PP constant temperature sample, heating the mixture to 280 ℃ and the pressure of 55bar to obtain a PP head material sample, carrying out injection molding on the mixture at the constant temperature of 280 ℃ for 5min to obtain a PP constant temperature sample, heating the mixture to 300 ℃ and the pressure of 50bar to obtain a PP head material sample, carrying out injection molding on the mixture at the constant temperature of 300 ℃ for 5min to obtain a PP constant temperature sample, heating the mixture to 320 ℃ and carrying out injection molding on the PP head material sample at the constant temperature of 45bar for 5min to obtain a PP constant temperature sample, and carrying out injection molding on the PP constant temperature sample to obtain a PP constant temperature sample, and detecting WH and △ E of the PP head layer sample and the PP constant temperature sample.

Example 2

The experiment and detection steps are the same as those of example 1, and the titanium dioxide product adopts a No. 2 sample.

Example 3

The experiment and detection steps are the same as those of example 1, and the titanium dioxide product adopts a No. 3 sample.

The results of the tests performed on the samples prepared in examples 1 to 3 under the same conditions are shown in FIGS. 1 and 2.

As can be seen from the analysis of the graphs 1 and 2, the temperature resistance of the titanium dioxide sample can be accurately detected to be the worst temperature resistance by adopting the method for detecting the temperature resistance of the titanium dioxide, the temperature resistance of the titanium dioxide sample 3 is obviously superior to that of the titanium dioxide sample 1, and the conclusion is consistent with the characteristic description of the known titanium dioxide 1-3.

From the embodiments 1 to 3, the whiteness is detected under different temperature conditions by adopting the fusion of the polypropylene resin (PP) and the titanium dioxide, and the temperature resistance of the titanium dioxide is evaluated through the whiteness and the color difference value, so that the accuracy of the measurement result is more intuitively and accurately ensured.

Claims

1. the method for detecting the temperature resistance of titanium dioxide, is characterized in that: comprise the steps:

a. Evenly mix titanium dioxide and polypropylene resin to obtain a mixture;

b. Take the mixture and inject it into a PP head material sample at different temperatures and pressures, and then take the mixture again and inject it into a PP constant temperature sample after constant temperature on the basis of the different temperatures;

c. Use a spectrophotometer to measure the L, a, b values of the PP headstock sample and the PP constant temperature sample in step b, and calculate the Hunter whiteness and color difference ΔE.

2 . The method for detecting the temperature resistance of titanium dioxide according to claim 1 , wherein in step a, the addition amount of the titanium dioxide is 0.2wt% to 0.6wt% of the polypropylene resin. 3 .

3. The method for detecting temperature resistance of titanium dioxide according to claim 1, characterized in that: in step b, the mixture is injected into PP head material samples at 200 ℃, 280 ℃, 300 ℃, 320 ℃ respectively; The mixtures are respectively injection-molded into PP constant temperature samples after being kept at 200° C., 280° C., 300° C. and 320° C. for 5-15 minutes.

4. The method for detecting temperature resistance of titanium dioxide according to claim 3, wherein in step b, the pressure value corresponding to the 200°C is 80 or 85 bar; the pressure value corresponding to the 280°C is 50 or 50 bar. 55bar; the corresponding pressure value of 300°C is 45 or 50bar; the corresponding pressure value of 320°C is 40 or 45bar.

5 . The method for detecting the temperature resistance of titanium dioxide according to claim 1 , wherein in step c, the whiteness value is an average value of 3 to 5 times of detection. 6 .