A method for quickly detecting the tinting strength of titanium dioxide

Abstract

The present invention discloses a method for quickly detecting the tinting strength of titanium dioxide, comprising the following steps: S1. Preparation of black masterbatch: Mix 60-100 parts of PVC paste resin, 15-65 parts of plasticizer, 0.1-0.5 parts of carbon black, 2-5 parts of stabilizer, 5-10 parts of epoxidized soybean oil, and 10-15 parts of viscosity reducer evenly to obtain black masterbatch; S2. Respectively take standard sample titanium dioxide, titanium dioxide to be tested and black masterbatch and mix them evenly to obtain standard sample mixed slurry and to-be-tested mixed slurry; S3. Preparation of PVC film: Respectively prepare the standard sample mixed slurry and the to-be-tested mixed slurry into films, and then obtain standard sample PVC film and to-be-tested PVC film through high-temperature plasticization; S4. Use a color difference meter for testing. The testing method of the present invention does not require large-scale equipment, is simple to operate, convenient to prepare, and has good repeatability and reproducibility.

Description

Technical Field

[0001] The invention belongs to the field of titanium dioxide detection, and specifically relates to a method for quickly detecting the decolorizing power of titanium dioxide. Background Art

[0002] In order to distinguish between white pigments and coloring pigments, the coloring ability of coloring pigments is usually called coloring power, and the coloring ability of white pigments is called decolorizing power, that is, the ability of titanium dioxide to make the colored object have color with its own color when used as a white colorant. Although the formulas and steps of the test methods for decolorizing power of different plastic systems are different, the basic principles are similar: the ability of white pigment (titanium dioxide) and another pigment (carbon black) to lighten the color of another pigment (carbon black) after mixing is the decolorizing power.

[0003] Being able to stably, accurately and quickly test the tinting power of titanium dioxide in plastic systems can not only support its application and promotion, but also reflect the physical and chemical properties of titanium dioxide itself (such as particle size and its distribution, dispersibility in plastic matrix and compatibility with matrix, etc.). In production testing, the tinting power of titanium dioxide is generally determined by the following four methods:

[0004] 1) Visual comparison (mix the pigment with ultramarine or carbon black, grind into a paste with linseed oil, and compare with scraping)

[0005] 2) Relative scattering power

[0006] 3) Reynolds number (TCS value)

[0007] 4) Relative decolorizing power in plastics.

[0008] Although visual comparison of tinting power is the fastest and most convenient, it requires a lot of experience from the testers, is highly subjective, and can only compare good and bad but cannot be quantified. It is difficult to distinguish products with similar tinting power and is not suitable for multi-sample evaluation.

[0009] There is a significant difference between the test results of Reynolds number and relative tinting power, and the test results and trends are inconsistent. Reynolds number generally has a certain guiding role in the color matching of coating applications. Usually, black color paste (first optimized from linseed oil) is prepared using substances similar to the coating system. Its results are not very applicable to the evaluation of the tinting power of products in plastic systems.

[0010] The relative decolorizing power test in plastics is to prepare a gray PVC color piece with a uniform mixture of pigment and carbon black through roller refining and molding, and then test the result with a colorimeter. The PVC system is representative and suitable for the test of titanium dioxide in plastic systems, but the double-roller refining process has high requirements on human operation, and some materials will be lost during the processing, and a lot of smoke will be generated. Even if the refining steps are the same, the refining effects of different testers are still different, which affects the reproducibility and repeatability of the results. Summary of the invention

[0011] The purpose of the present invention is to provide a method for quickly detecting the tinting power of titanium dioxide in order to solve the deficiencies of the prior art.

[0012] The purpose of the present invention is achieved by the following technical solutions:

[0013] A method for rapidly detecting the tinting power of titanium dioxide comprises the following steps:

[0014] S1. Preparation of black masterbatch: In parts by weight, 60 to 100 parts of PVC paste resin, 15 to 65 parts of plasticizer, 0.1 to 0.5 parts of carbon black, 2 to 5 parts of stabilizer, 5 to 10 parts of epoxidized soybean oil, and 10 to 15 parts of viscosity reducer are mixed to obtain a black masterbatch;

[0015] S2. Take the standard titanium dioxide, the titanium dioxide to be tested and the black masterbatch and mix them evenly to obtain the standard mixed slurry and the mixed slurry to be tested; the addition amount of the standard titanium dioxide and the titanium dioxide to be tested is 3 to 10% of the mass of the black masterbatch;

[0016] S3. PVC film preparation: preparing the standard sample mixed slurry and the mixed slurry to be tested into films respectively, and then plasticizing them at high temperature to obtain the standard sample PVC film and the PVC film to be tested;

[0017] S4. Use a colorimeter to test the standard PVC film and the PVC film to be tested respectively.

[0018] Preferably, the polymerization degree of the PVC paste resin is 1000-1400.

[0019] Preferably, the plasticizer in step S1 is any one or a combination of DOP and DIDP; the stabilizer is a liquid barium zinc stabilizer, wherein the mass percentage of barium is 9.8-10.2%, and the mass percentage of zinc is 1.95-2.35%; and the viscosity reducer is a polyether viscosity reducer.

[0020] Preferably, the mixing of the raw materials in step S1 is carried out by one or more methods selected from high-speed stirring, shaking, and grinding.

[0021] Preferably, the mixing of the raw materials in step S1 is carried out by shaking.

[0022] Preferably, step S1 further comprises the step of removing bubbles from the black masterbatch by vacuum.

[0023] Preferably, the film forming method in step S3 is scraping, spin coating or dip coating.

[0024] Preferably, the film layer thickness in step S3 is 75-150 μm.

[0025] Preferably, the high temperature plasticizing temperature in step S3 is 190-210° C., and the plasticizing time is 3-7 minutes.

[0026] Preferably, the calculation formula for the tinting power of the titanium dioxide to be tested in step S4 is as follows:

[0027] Tinting power 比样 =(Y value 比样 / Y value 标样 )×100% Formula 1

[0028] Among them, the tinting power 比样 The relative tinting power of the titanium dioxide to be tested, expressed as a percentage, Y value 比样 is the color difference value of the PVC film to be tested, Y value 标样 It is the color difference value of the standard PVC film.

[0029] The present invention innovatively proposes to use PVC paste resin as the test matrix, add plasticizer, carbon black and other additives to prepare black masterbatch; after titanium dioxide and black masterbatch are evenly mixed, a film is made, and after high-temperature plasticization, a test is performed using a colorimeter. This test method does not require large equipment, is simple to operate, is convenient to prepare, and has good repeatability and reproducibility. DETAILED DESCRIPTION

[0030] The method for rapidly detecting the tinting power of titanium dioxide provided in the present application comprises the following steps:

[0031] S1. Preparation of black masterbatch: In parts by weight, 60 to 100 parts of PVC paste resin, 15 to 65 parts of plasticizer, 0.1 to 0.5 parts of carbon black, 2 to 5 parts of stabilizer, 5 to 10 parts of epoxidized soybean oil, and 10 to 15 parts of viscosity reducer are mixed to obtain a black masterbatch;

[0032] S2. Take the standard titanium dioxide, the titanium dioxide to be tested and the black masterbatch and mix them evenly to obtain the standard mixed slurry and the mixed slurry to be tested; the addition amount of the standard titanium dioxide and the titanium dioxide to be tested is 3 to 10% of the mass of the black masterbatch;

[0033] S3. PVC film preparation: prepare the standard sample mixed slurry and the mixed slurry to be tested into films respectively, and then plasticize them at high temperature to obtain the standard sample PVC film and the PVC film to be tested;

[0034] S4. Use a colorimeter to test the standard PVC film and the PVC film to be tested respectively.

[0035] The present invention innovatively proposes to use PVC paste resin as a test matrix, add plasticizer, carbon black and other additives to prepare a black masterbatch; after titanium dioxide and the black masterbatch are evenly mixed, a film is prepared, and after high-temperature plasticization, a test is performed using a colorimeter.

[0036] The factors that affect the accuracy of colorimeter testing mainly include the uniformity of pigment dispersion. In the prior art, PVC resin is processed into films using solid state processing, and the uniformity of pigment dispersion is poor, which affects the accuracy of the test.

[0037] The present application adopts polyvinyl chloride (PVC) paste resin, which is a product branch of polyvinyl chloride resin. PVC paste resin is named for its highly dispersible powder used in paste processing. Due to its excellent paste-forming performance and good dispersion performance, polyvinyl chloride paste resin can be mixed with plasticizer and stirred to form a suspension that is more stable than ordinary polyvinyl chloride resin, that is, PVC paste; wherein carbon black is a black colorant; among the additives, epoxy soybean oil has excellent thermal processing and flexibility, and can be used as an auxiliary plasticizer. Since the masterbatch prepared by PVC paste resin has a high viscosity, it is not conducive to film making. Therefore, adding a certain amount of viscosity reducer can improve its fluidity and make the carbon black more evenly dispersed. Adding a certain amount of stabilizer can improve the stability of the plasticized film to heat, light, etc.

[0038] Therefore, by using PVC paste resin, adding plasticizers and other additives to prepare a uniformly dispersed and stable black masterbatch, and then mixing it with titanium dioxide, and using liquid processing to make a film, the difficulty of pigment dispersion is reduced, and batch dispersion can be carried out by conventional dispersion methods such as high stirring, shaking, grinding, etc., which can effectively avoid the loss of mixed materials during the dispersion process while improving efficiency, thereby improving the accuracy of the test results. Additives such as viscosity reducers can further improve the uniformity of pigment dispersion and the fluidity of color pastes. Through high-temperature plasticization, a film to be tested with uniform pigment dispersion and consistent thickness can be prepared quickly and conveniently, which can avoid the use of high-temperature, high-shear rolling equipment, and the experimental repeatability is good. At the same time, the processing conditions are reduced, and the high-temperature, high-shear process of rolling is avoided. Various added additives are heated to produce a large amount of smoke (plasticizers and other additives will produce a large amount of smoke during rolling), which can significantly improve the experimental environment.

[0039] Therefore, the test method of the present application does not require large-scale equipment and is simple to operate. It can quickly and easily prepare a film to be tested with uniform pigment dispersion and consistent thickness. It has low operating requirements for personnel and good repeatability and reproducibility. Especially for the tinting power test of large quantities of samples, a large amount of black masterbatch can be pre-prepared, and unified film making, plasticization and testing can be achieved, thereby maximizing the efficiency of the test.

[0040] The mixing of the raw materials in the above steps can be assisted by high-speed stirring, shaking, grinding and other methods to ensure uniform dispersion of the titanium dioxide. It is further preferred to use the shaking method, which has a better dispersion effect than other mixing methods.

[0041] Preferably, the degree of polymerization of the PVC paste resin is between 1000 and 1400.

[0042] Preferably, the plasticizer in step S1 is selected from any one or a combination of DOP and DIDP. The stabilizer is a liquid barium zinc stabilizer, wherein the mass percentage of barium is 9.8-10.2% and the mass percentage of zinc is 1.95-2.35%. The viscosity reducer is a polyether viscosity reducer.

[0043] Preferably, step S1 also includes the step of removing bubbles from the black masterbatch by vacuum to prevent the bubbles from affecting the uniformity of pigment distribution and thus affecting the detection results.

[0044] Preferably, the film forming method in step S3 is blade coating, spin coating or dip coating.

[0045] The film thickness is also an important factor affecting the accuracy of the colorimeter test. Preferably, the film thickness in step S3 is 75-150 μm.

[0046] Preferably, the high temperature plasticizing temperature in step S3 is 190-210° C. and the time is 3-7 minutes.

[0047] Preferably, in step S4, the Y value of the standard sample is taken as 100% for conversion, and the calculation formula for the tinting power of the titanium dioxide to be tested is:

[0048] Tinting power 比样 =(Y value 比样 / Y value 标样 )×100%

[0049] Among them, the tinting power 比样 The relative decolorizing power of the titanium dioxide to be tested is expressed as a percentage. The Y value is the basic value that can reflect the decolorizing ability of the sample directly tested by the equipment. It can be calculated from the three stimulus values ​​xyz. 比样 is the color difference value of the PVC film to be tested, Y value 标样 is the color difference value of the standard PVC film.

[0050] Example 1

[0051] Weigh 100 parts of PVC paste resin, 65 parts of plasticizer DIDP, 2.5 parts of liquid barium zinc stabilizer, 15 parts of polyether viscosity reducer for PVC paste resin, 7 parts of epoxy soybean oil and 0.5 parts of carbon black and add them to a table stirrer. Stir at 2000 speed for 20 minutes, let it stand for 24 hours, and vacuum to remove bubbles to obtain a black masterbatch. Add 4g of the titanium dioxide to be tested to 50g of the black masterbatch, stir and disperse for 20 minutes, and then use a 150μm wet film preparation device to apply a film. The film thickness is 150μm. Put it in an electric hot air drying oven and plasticize it at 205℃ for 5 minutes, then take it out and cool it for testing.

[0052] Repeat the above operation to prepare the test sample of the standard titanium dioxide. Use a colorimeter to scan and detect the titanium dioxide plasticized sample to be tested and the standard titanium dioxide plasticized test sample to be tested, and calculate the tinting power of the titanium dioxide to be tested according to Formula 1. The results are shown in Table 1.

[0053] Example 2

[0054] Weigh 100g of PVC paste resin, 65g of plasticizer DIDP, 2.5g of liquid barium zinc stabilizer, 15g of polyether viscosity reducer for PVC paste resin, 0.5g of carbon black, 7g of epoxy soybean oil, and 120g of 5mm glass beads (as a vibrating dispersion medium), put them into an oscillator, vibrate and disperse for 20min, let them stand for 24h, and vacuum to remove bubbles and then treat them to obtain a black masterbatch. Add 4g of the titanium dioxide to be tested into 50g of the black masterbatch, vibrate and disperse for 20min through a formula optimization machine, and then use a 150μm wet film preparation device to scrape and form a film with a film thickness of 150μm, then put them into an electric hot air drying oven at 205℃ for high temperature plasticization for 5min, take them out and cool them for testing.

[0055] Repeat the above operation to prepare the test sample of the standard titanium dioxide. Use a colorimeter to scan and detect the titanium dioxide plasticized sample to be tested and the standard titanium dioxide plasticized test sample to be tested, and calculate the tinting power of the titanium dioxide to be tested according to Formula 1. The results are shown in Table 1.

[0056] Comparative Example

[0057] Weigh 100g of PVC resin, add pigment (5g of titanium dioxide / 0.5g of carbon black), 1.3g of liquid barium zinc stabilizer, and 0.2g of stearic acid in turn, stir for 2min, add 1.5g of epoxy soybean oil and 3.5g of plasticizer DIDP, continue mixing for 3min, and mix evenly; add the mixed materials into a double roller and start timing; after the powder is plasticized into sheets, repeatedly make triangular bags; after 5min of rolling and mixing evenly, take off the sheets, cut them after cooling, put them into a flat vulcanizer for hot pressing at 160℃, and take them out for testing.

[0058] Repeat the above operation to prepare the test sample of the standard titanium dioxide. Use a colorimeter to scan and detect the titanium dioxide plasticized sample to be tested and the standard titanium dioxide plasticized test sample to be tested, and calculate the tinting power of the titanium dioxide to be tested according to Formula 1. The results are shown in Table 1.

[0059] Implementation and Comparative Example Results:

[0060] Table 1 The tinting power data of the same sample tested by different test methods

[0061]

[0062] The L and b values ​​can reflect the dispersion of titanium dioxide to a certain extent. The higher the L value and the lower the b value, the better the dispersion.

[0063] From the above results, the Y value fluctuation of the comparative example after repeated 5 times of roller refining sample test is the largest, and the relative tinting power is the smallest; the Y value fluctuation of the result of repeated 5 times of test in Example 2 is the smallest, which is better than Example 1 and the comparative example, and the relative tinting power value is the largest, which shows that the vibration grinding method can better disperse titanium dioxide and carbon black evenly, making its test results more accurate and stable. In addition, the detection time of Examples 1 and 2 is significantly reduced compared with the comparative example, and the more samples are tested, the more obvious the efficiency improvement is.

[0064] Example 3

[0065] Weigh 80g of PVC paste resin, 40g of plasticizer DOP, 3g of liquid barium zinc stabilizer, 12g of polyether viscosity reducer for PVC paste resin, 0.3g of carbon black, 6g of epoxy soybean oil, and 100g of 5mm glass beads (as a vibrating dispersion medium), put them into an oscillator, vibrate and disperse for 20min, let them stand for 24h, vacuum and remove bubbles, and then get a black masterbatch. Add 3g of titanium dioxide to be tested into 50g of black masterbatch, vibrate and disperse for 20min through a formula optimization machine, and then apply a film with a film thickness of 100μm, then put them into an electric hot air drying oven at 200℃ for high temperature plasticization for 6min, take them out and cool them for testing.

[0066] Repeat the above operation to prepare the test sample of the standard titanium dioxide. Use a colorimeter to scan and detect the titanium dioxide plasticized sample to be tested and the standard titanium dioxide plasticized test sample to be tested, and calculate the decolorizing power of the titanium dioxide to be tested according to Formula 1.

[0067] Example 4

[0068] Weigh 60g of PVC paste resin, 20g of plasticizer DOP, 4g of liquid barium zinc stabilizer, 10g of polyether viscosity reducer for PVC paste resin, 0.1g of carbon black, 5g of epoxy soybean oil, and 80g of 5mm glass beads (as a vibrating dispersion medium), put them into an oscillator, vibrate and disperse for 20 minutes, let them stand for 24 hours, and vacuum to remove bubbles and then treat them to obtain a black masterbatch. Add 2g of the titanium dioxide to be tested into 50g of the black masterbatch, vibrate and disperse for 20 minutes through a formula optimization machine, and then apply a film with a film thickness of 80μm, then put it into an electric hot air drying oven at 195℃ for 7 minutes, take it out and cool it for testing.

[0069] Repeat the above operation to prepare the test sample of the standard titanium dioxide. Use a colorimeter to scan and detect the titanium dioxide plasticized sample to be tested and the standard titanium dioxide plasticized test sample to be tested, and calculate the decolorizing power of the titanium dioxide to be tested according to Formula 1.

[0070] Although preferred embodiments of the present invention have been described, additional changes and modifications may be made to these embodiments by those skilled in the art once the basic inventive concepts are known. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention. Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for quickly detecting the tinting strength of titanium dioxide, characterized in that, it includes the following steps: S1. Preparation of black masterbatch: By weight, mix 60 - 100 parts of PVC paste resin, 15 - 65 parts of plasticizer, 0.1 - 0.5 parts of carbon black, 2 - 5 parts of stabilizer, 5 - 10 parts of epoxidized soybean oil, and 10 - 15 parts of viscosity reducer evenly to obtain black masterbatch; the polymerization degree of the PVC paste resin is 1000 - 1400; the viscosity reducer is a polyether-based viscosity reducer; S2. Respectively take the standard sample titanium dioxide, the titanium dioxide to be tested and the black masterbatch and mix them evenly to obtain the standard sample mixed slurry and the to-be-tested mixed slurry; the addition amounts of the standard sample titanium dioxide and the to-be-tested titanium dioxide are 3 - 10% of the mass of the black masterbatch; S3. Preparation of PVC film: Respectively prepare the standard sample mixed slurry and the to-be-tested mixed slurry into films, and then through high-temperature plasticization to obtain the standard sample PVC film and the to-be-tested PVC film; the thicknesses of the standard sample PVC film and the to-be-tested PVC film are 75 - 150 μm; the high-temperature plasticization temperature is 190 - 210 °C, and the plasticization time is 3 - 7 min; S4. Use a color difference meter to test the standard sample PVC film and the to-be-tested PVC film respectively.

2. The method for quickly detecting the tinting strength of titanium dioxide according to claim 1, characterized in that, in step S1, the plasticizer is any one or a combination of two selected from DOP and DIDP; the stabilizer is a liquid barium-zinc stabilizer, wherein the mass percentage content of barium is 9.8 - 10.2%, and the mass percentage content of zinc is 1.95 - 2.35%.

3. The method for quickly detecting the tinting strength of titanium dioxide according to claim 1, characterized in that, in step S1, the mixing of the raw materials is carried out by one or more methods selected from high-speed stirring, oscillation, and grinding.

4. The method for quickly detecting the tinting strength of titanium dioxide according to claim 3, characterized in that, in step S1, the mixing of the raw materials is carried out by the oscillation method.

5. The method for quickly detecting the tinting strength of titanium dioxide according to claim 1, characterized in that, step S1 further includes the step of removing air bubbles from the black masterbatch by vacuum.

6. The method for quickly detecting the tinting strength of titanium dioxide according to claim 1, characterized in that, in step S3, the film-forming method is blade coating, spin coating or dip coating.

7. The method for quickly detecting the tinting strength of titanium dioxide according to claim 1, characterized in that, the calculation formula for the tinting strength of the to-be-tested titanium dioxide in step S4 is as shown in formula one: Tinting strength 比样 = (Y value 比样 / Y value 标样 ) × 100% Equation 1 Among them, tinting strength 比样 is the relative tinting strength of the titanium dioxide to be tested, expressed as a percentage, and Y value 比样 is the color difference value of the PVC film to be tested, and Y value 标样 is the color difference value of the standard sample PVC film.

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