A method for predicting the dispersibility of titanium dioxide in plastics

Abstract

This invention discloses a method for predicting the dispersibility of titanium dioxide in plastics, comprising the following steps: Step 1: After drying, titanium dioxide is loaded into a gas chromatography column using a suction method; Step 2: The surface free energy of titanium dioxide is tested using reverse gas chromatography; Step 3: The resin is processed into a plastic plate; Step 4: The surface free energy of the plastic plate is tested using a seated drop method; Step 5: The interfacial tension and adhesion work are calculated using the surface free energy of titanium dioxide and the surface free energy of the plastic plate; Step 6: The dispersibility of titanium dioxide in plastics is evaluated based on the interfacial tension and adhesion work. The method of this invention evaluates the surface properties of titanium dioxide based on the detection of its surface free energy, which is beneficial for assessing the dispersibility of titanium dioxide in different dispersion systems. This method for predicting the dispersibility of titanium dioxide in plastics can improve the efficiency of titanium dioxide dispersibility testing in plastics, reduce labor intensity, and lower labor costs.

Description

Technical Field

[0001] This invention relates to the field of titanium dioxide application technology, and more particularly to a method for predicting the dispersibility of titanium dioxide in plastics. Background Technology

[0002] Titanium dioxide, a white inorganic pigment, is widely used in coatings and plastics. Plastics are the second largest user of titanium dioxide, accounting for over 20% of the global total. The dispersion of titanium dioxide in plastics directly affects the optical properties of the material, such as whiteness and opacity; it also influences the material's processing properties, such as equilibrium torque, weather resistance, mechanical properties, and electrical conductivity.

[0003] The dispersibility of titanium dioxide is mainly assessed by measuring the pressure filtration value through scraping and extruding a mixture of titanium dioxide with a representative slurry or with polypropylene. However, this method is too limited and not applicable to many plastic systems. Currently, there are two other methods in the plastics industry to test the dispersibility of titanium dioxide in plastics: one is to measure the torque by blending titanium dioxide with resin in a certain proportion; the other is to blend titanium dioxide with resin to form a masterbatch and then blow film it to measure the crystal point. However, these methods have the disadvantages of being difficult to test, having a long testing process, and requiring a lot of equipment.

[0004] In existing technologies, materials from different extrusion stages are calcined at temperatures high enough to decompose the resin, and the solid content of these materials is calculated. The ratio of these solid contents is then used to characterize the dispersibility of titanium dioxide in plastics. However, this method requires repeated testing for different plastics, and the testing process remains complex.

[0005] Therefore, researching a simple method for detecting the dispersibility of titanium dioxide in plastics is a technical problem to be solved. Summary of the Invention

[0006] The main objective of this invention is to provide a method for predicting the dispersibility of titanium dioxide in plastics by relating titanium dioxide to the surface properties of plastics through surface free energy, thereby predicting the dispersibility of titanium dioxide in plastics.

[0007] To solve at least one of the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] According to the present invention, a method for predicting the dispersibility of titanium dioxide in plastics is provided, comprising the following steps:

[0009] Step 1: After drying the titanium dioxide, pack it into a gas chromatography column using a suction method;

[0010] Step 2: Measure the surface free energy of titanium dioxide using reverse gas chromatography;

[0011] Step 3: Process the resin into plastic sheets;

[0012] Step 4: Test the surface free energy of the plastic plate using the seated drop method;

[0013] Step 5: Calculate the interfacial tension and adhesion work using the surface free energy of titanium dioxide and the surface free energy of the plastic plate;

[0014] Step 6: Evaluate the dispersibility of titanium dioxide in plastics based on interfacial tension and adhesion work.

[0015] Furthermore, in step one, 1-2 grams of titanium dioxide are weighed after passing through a 50-mesh sieve and loaded into a gas chromatography column.

[0016] Furthermore, in step two, the test reagents for reverse gas chromatography are heptane, octane, nonane, heptane, dichloromethane, and toluene.

[0017] Furthermore, in step two, the packed column for reverse gas chromatography needs to be aged at 120 degrees Celsius for 2 hours before use, and each packed column needs to be aged again after the test temperature.

[0018] Furthermore, in step two, the gas chromatography settings for reverse gas chromatography are as follows: sample chamber temperature is 180 degrees Celsius, FID detector temperature is 200 degrees Celsius, and packed column temperature is 70, 80, 90, 100, and 110 degrees Celsius.

[0019] Furthermore, in step three, the resin is processed into a plastic sheet with a thickness of 2-3mm using a flat vulcanizing machine or an injection molding machine.

[0020] Furthermore, in step four, the test liquids are water, diiodomethane, and propylene glycol, and each liquid is tested five times and the average value is calculated.

[0021] Furthermore, in step two, the dispersion energy of the surface free energy is calculated using the Dorris / Gray method, and the acid-base part is calculated using the polarizability method; in step four, the surface free energy is calculated using the LW-AB method.

[0022] Furthermore, in step five, the formula for calculating interfacial tension is:

[0023]

[0024] Where, γ SL The interfacial tension between titanium dioxide and plastic;

[0025] The surface free energy dispersion component of titanium dioxide;

[0026] The surface free energy dispersion component of the plastic;

[0027] The surface free energy acid content of titanium dioxide;

[0028] The surface free energy of titanium dioxide is the base component.

[0029] The surface free energy acid component of the plastic;

[0030] This represents the basic component of the surface free energy of the plastic.

[0031] Furthermore, in step five, the formula for calculating the adhesion work is:

[0032] W a =γ S +γ L -γ SL

[0033] Among them, W a For adhesion work;

[0034] γ SL The interfacial tension between titanium dioxide and plastic;

[0035] γ S The surface free energy of titanium dioxide;

[0036] γ L This represents the surface free energy of the plastic.

[0037] The beneficial effects of this invention are as follows:

[0038] The method for estimating the dispersibility of titanium dioxide in plastics according to the present invention can improve the efficiency of titanium dioxide dispersibility detection in plastics, reduce labor intensity, and reduce labor costs.

[0039] The method for predicting the dispersibility of titanium dioxide in plastics according to the present invention can efficiently guide the stabilization and improvement of titanium dioxide quality; it reduces the amount of manual labor required for product quality inspection, thereby lowering the labor cost of pure titanium dioxide. Furthermore, by linking titanium dioxide to the surface properties of plastics through surface free energy, the method for predicting the dispersibility of titanium dioxide in plastics saves significant manpower, resources, and time, and is highly operable. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1A flowchart illustrating a method for estimating the dispersibility of titanium dioxide in plastics according to an embodiment of the present invention is shown.

[0042] Figure 2 The filter press values ​​of the samples from test examples 1-3 of the screw extruder are shown. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0044] Figure 1 A flowchart of a method for estimating the dispersibility of titanium dioxide in plastics according to the present invention is shown, comprising the following steps:

[0045] Step 1: After drying the titanium dioxide, pack it into a gas chromatography column using a suction method;

[0046] Step 2: Measure the surface free energy of titanium dioxide using reverse gas chromatography;

[0047] Step 3: Process the resin into plastic sheets;

[0048] Step 4: Test the surface free energy of the plastic plate using the seated drop method;

[0049] Step 5: Calculate the interfacial tension and adhesion work using the surface free energy of titanium dioxide and the surface free energy of the plastic plate;

[0050] Step 6: Evaluate the dispersibility of titanium dioxide in plastics based on interfacial tension and adhesion work.

[0051] In some embodiments, in step one, 1-2 grams of titanium dioxide are weighed after passing through a 50-mesh sieve and loaded into a gas chromatography packed column.

[0052] In some embodiments, in step two, the test reagents for reverse gas chromatography are heptane, octane, nonane, heptane, dichloromethane, and toluene.

[0053] In some embodiments, in step two, the packed column for reverse gas chromatography needs to be aged at 120 degrees Celsius for 2 hours before use, and each packed column needs to be aged again after the test temperature.

[0054] In some embodiments, in step two, the gas chromatography settings for reverse gas chromatography are: sample chamber temperature of 180 degrees Celsius, FID detector temperature of 200 degrees Celsius, and packed column temperature of 70, 80, 90, 100, and 110 degrees Celsius.

[0055] In some embodiments, in step three, the resin is processed into a plastic sheet with a thickness of 2-3 mm using a flat vulcanizing machine or an injection molding machine.

[0056] In some embodiments, in step four, the test liquid is water, diiodomethane, or propylene glycol, and each liquid is tested five times and the average value is calculated.

[0057] In some embodiments, in step two, the dispersion energy of the surface free energy is calculated using the Dorris / Gray method, and the acid-base part is calculated using the polarizability method; in step four, the surface free energy is calculated using the LW-AB method.

[0058] In some embodiments, the formula for calculating interfacial tension in step five is as follows:

[0059]

[0060] Where, γ SL The interfacial tension between titanium dioxide and plastic;

[0061] The surface free energy dispersion component of titanium dioxide;

[0062] The surface free energy dispersion component of the plastic;

[0063] The surface free energy acid content of titanium dioxide;

[0064] The surface free energy of titanium dioxide is the base component.

[0065] The surface free energy acid component of the plastic;

[0066] This represents the basic component of the surface free energy of the plastic.

[0067] In some embodiments, the formula for calculating the adhesion work in step five is as follows:

[0068] W a =γ S +γ L -γ SL

[0069] Among them, W a For adhesion work;

[0070] γ SL The interfacial tension between titanium dioxide and plastic;

[0071] γ S The surface free energy of titanium dioxide;

[0072] γ L This represents the surface free energy of the plastic.

[0073] Example

[0074] The present invention will be further described in detail through the following embodiments and comparative examples. Furthermore, the embodiments represent one aspect of the invention, and the invention is not limited thereto.

[0075] Three types of titanium dioxide were prepared for use: Sample 1, Sample 2 and Sample 3.

[0076] Three types of titanium dioxide were dried and passed through a 50-mesh sieve. They were then packed into a packed column using a suction method, with packing masses of 1.56 g, 1.562 g, and 1.491 g, respectively. The sample chamber temperature was 180°C, the FID detector temperature was 200°C, and the packed column temperature was 70, 80, 90, 100, and 110°C. The retention times of the probe molecules heptane, octane, nonane, heptane, dichloromethane, and toluene were measured. The retention volume Vg was calculated based on the retention times and other conditions. The dispersive component of the surface energy was calculated using the Dorris / Gray method, and the acid-base component was calculated using the polarizability method. The surface free energies of the three titanium dioxides are shown in Table 1 below.

[0077] PP (polypropylene) masterbatch was pressed into plates on a flat vulcanizing machine. The water contact angle of water, diiodomethane, and ethylene glycol on the PP plate was tested by the seat drop method. The surface free energy of PP was obtained by LW-AB, as shown in Table 1 below.

[0078] Table 1

[0079] Sample 1 Sample 2 Sample 3 PP <![CDATA[γ - ]]> 0.01037006 0.01690556 0.01127514 0.12232078 <![CDATA[γ + ]]> 0.01348964 0.01010471 0.0171272 0.00952681 <![CDATA[γ sp ]]> 0.02365488 0.02614007 0.02779292 0.06827378 <![CDATA[γ LW ]]> 49.14479 65.72095 56.974485 29.0011284 γ 49.1684449 65.7470901 57.0022779 29.0694022

[0080] in, γ=γ sp +γ LW .

[0081] The interfacial tension and adhesion work between titanium dioxide and PP are shown in Table 2.

[0082] Table 2

[0083] Sample 1 Sample 2 Sample 3 <![CDATA[γ SL ]]> 2.63164377 7.40569577 4.66182355 <![CDATA[W a ]]> 75.6059969 87.410087 81.4104793

[0084] In the formula for calculating the work of adhesion, γ S The surface free energy of titanium dioxide is given by γ, which is the total free energy γ of the titanium dioxide samples in Table 1. L The surface free energy of the plastic is calculated using the total free energy γ of PP from Table 1. For example, the adhesion work W of sample 1... a =49.1684449+29.0694022-2.63164377=75.6059969.

[0085] Interfacial tension (γ) SL ) and adhesion work (W) aThe higher the value of ), the better the dispersibility of titanium dioxide in plastics. From the above results, the dispersibility of the three titanium dioxide samples in PP is: Sample 2 > Sample 3 > Sample 1.

[0086] The above titanium dioxide samples were subjected to pressure filtration value tests using PP as the dispersion medium. The results are as follows: Figure 2 As shown, the filtration pressure values ​​of samples 1, 2, and 3 were 9.73 bar / g, 7.25 bar / g, and 9.70 bar / g, respectively. The dispersibility of titanium dioxide in PP was: Sample 2 > Sample 3 > Sample 1, consistent with the results predicted by interfacial tension and adhesion work. Among them, titanium dioxide No. 2 showed better dispersibility. Therefore, the accuracy of the method for predicting the dispersibility of titanium dioxide in plastics in the embodiments of the present invention is also verified.

[0087] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of the different aspects of the invention as described above exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for predicting the dispersibility of titanium dioxide in plastics, characterized in that, Includes the following steps: Step 1: After drying the titanium dioxide, pack it into a gas chromatography column using a suction method; Step 2: Measure the surface free energy of titanium dioxide using reverse gas chromatography; Step 3: Process the resin into plastic sheets; Step 4: Test the surface free energy of the plastic plate using the seated drop method; Step 5: Calculate the interfacial tension and adhesion work using the surface free energy of titanium dioxide and the surface free energy of the plastic plate; Step 6: Evaluate the dispersibility of titanium dioxide in plastics based on interfacial tension and adhesion work; in, In step five, the formula for calculating interfacial tension is: Where, γ SL The interfacial tension between titanium dioxide and plastic; The surface free energy dispersion component of titanium dioxide; The surface free energy dispersion component of the plastic; The surface free energy acid content of titanium dioxide; The surface free energy of titanium dioxide is the base component. The surface free energy acid component of the plastic; The basic component of the surface free energy of plastic; Formula for calculating adhesion work: W a = c S +g L -c SL Among them, W a For adhesion work; γ SL The interfacial tension between titanium dioxide and plastic; γ S γ is the surface free energy of titanium dioxide; L This represents the surface free energy of the plastic.

2. The method according to claim 1, characterized in that, In step one, after drying the titanium dioxide, pass it through a 50-mesh sieve and weigh 1-2 grams, then pack it into a gas chromatography column.

3. The method according to claim 1, characterized in that, In step two, the test reagents for reverse gas chromatography are heptane, octane, nonane, heptane, dichloromethane, and toluene.

4. The method according to claim 1, characterized in that, In step two, the packed columns for reverse gas chromatography need to be aged at 120 degrees Celsius for 2 hours before use, and each packed column needs to be aged again after the test temperature.

5. The method according to claim 1, characterized in that, In step two, the gas chromatography settings for reverse gas chromatography are as follows: sample chamber temperature is 180 degrees Celsius, FID detector temperature is 200 degrees Celsius, and packed column temperature is 70, 80, 90, 100, and 110 degrees Celsius.

6. The method according to claim 1, characterized in that, In step three, the resin is processed into a plastic sheet with a thickness of 2-3mm using a flat vulcanizing machine or injection molding machine.

7. The method according to claim 1, characterized in that, In step four, the test liquids are water, diiodomethane, and propylene glycol. Each liquid is tested five times and the average value is calculated.

8. The method according to claim 1, characterized in that, In step two, the dispersion energy of the surface free energy is calculated using the Dorris / Gray method, and the acid-base part is calculated using the polarizability method; in step four, the surface free energy is calculated using the LW-AB method.

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