Polyvinyl chloride calendering film as well as preparation method and hue detection method thereof

Abstract

The invention relates to the technical field of polyvinyl chloride film production. The invention provides a polyvinyl chloride calendering film as well as a preparation method and a hue detection method thereof, and the preparation method of the polyvinyl chloride calendering film comprises the following steps: uniformly mixing polyvinyl chloride resin, a plasticizer, a stabilizer and titanium dioxide together to obtain a mixture; calendering the mixture for the first time to obtain a calendered film with a first thickness; and adding carbon black into the calendered film with the first thickness, and carrying out second calendering to obtain a calendered film with a second thickness which is smaller than the first thickness. Through the scheme of the invention, the polyvinyl chloride calendering film with uniformly distributed carbon black can be obtained, the color difference of the black polyvinyl chloride calendering film is reduced, the color phase of the black polyvinyl chloride calendering film is controllable, the appearance quality of the polyvinyl chloride calendering film is improved, the use performance of the polyvinyl chloride calendering film is improved, and the service life of the polyvinyl chloride calendering film is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of polyvinyl chloride film production, and particularly to a polyvinyl chloride calendered film, a preparation method thereof, and a hue detection method. Background Art

[0002] PVC (Polyvinyl chloride) is one of the most widely produced general plastics in the world. It has a relatively low price, a mature production process, and a wide range of sources. It can be made into various plastic products through a variety of molding processes, such as extrusion and injection molding, and is widely used in many fields such as construction, packaging, and electronics. PVC has good plasticity and decoration, and can produce various decorative materials through processes such as calendering and laminating to meet different decoration styles and needs.

[0003] For black PVC products, the difference in hue directly affects the appearance and quality of the products. At present, when producing black PVC calendered films, problems such as large color differences or color spots on the surface of the calendered film often occur due to uneven dispersion of carbon black.

[0004] In addition, there is currently no unified detection method for calendered films. Summary of the Invention

[0005] In view of this, the present invention provides a polyvinyl chloride calendered film, a preparation method thereof, and a hue detection method, which can solve the problems that existing black polyvinyl chloride calendered films are prone to uneven dispersion of carbon black during production, and there are large color differences or color spots on the surface of the calendered film, and there is no unified detection method for calendered films.

[0006] On the one hand, an embodiment of the present invention provides a method for preparing a polyvinyl chloride calendered film, which is characterized by including: Uniformly mixing polyvinyl chloride resin, plasticizer, stabilizer, and titanium dioxide together to obtain a mixture; Performing a first calendering on the mixture to obtain a calendered film with a first thickness; Adding carbon black to the calendered film with the first thickness and performing a second calendering to obtain a calendered film with a second thickness, and the second thickness is less than the first thickness.

[0007] In some embodiments, uniformly mixing polyvinyl chloride resin, plasticizer, stabilizer, and titanium dioxide together includes: Mixing polyvinyl chloride resin, plasticizer, stabilizer, and titanium dioxide together in a ratio of (50~150) g: (26~45) g: (1~5) g: (1~5) g.

[0008] In some embodiments, adding carbon black to the calendered film with the first thickness includes: Add (0.05 - 0.3) g of carbon black into the calendered film with the first thickness.

[0009] In some embodiments, the plasticizer is a phthalate plasticizer.

[0010] In some embodiments, the stabilizer includes a lead salt stabilizer and / or a metal soap stabilizer.

[0011] In some embodiments, the first thickness is in the range of 1 cm to 2 cm.

[0012] In some embodiments, the first calendering of the mixture to obtain the calendered film with the first thickness includes: Calender the mixture at 160 - 200 °C to obtain the calendered film with the first thickness.

[0013] On the other hand, the embodiments of the present invention also provide a method for detecting the hue of a polyvinyl chloride calendered film, including: Uniformly mix polyvinyl chloride resin, plasticizer, stabilizer and titanium dioxide together to obtain a mixture; Perform the first calendering on the mixture to obtain the calendered film with the first thickness; Add carbon black into the calendered film with the first thickness and perform the second calendering to obtain the calendered film with the second thickness, where the second thickness is less than the first thickness; Cut out the test sample from the calendered film with the second thickness; Perform color difference detection on the test sample based on a spectrophotometer.

[0014] On the other hand, the embodiments of the present invention also provide a polyvinyl chloride calendered film, including: polyvinyl chloride resin, plasticizer, stabilizer, titanium dioxide and carbon black, and the polyvinyl chloride calendered film is prepared by the preparation method of the polyvinyl chloride calendered film described in any one of the above embodiments.

[0015] In some embodiments, the ratio of polyvinyl chloride resin, plasticizer, stabilizer, titanium dioxide and carbon black in the polyvinyl chloride calendered film is: (50 - 150) g : (26 - 45) g : (1 - 5) g : (1 - 5) g : (0.05 - 0.3) g.

[0016] The present invention has at least the following beneficial effects: The present invention provides a polyvinyl chloride calendered film, a preparation method thereof, and a hue detection method. The preparation method of the polyvinyl chloride calendered film includes: uniformly mixing polyvinyl chloride resin, a plasticizer, a stabilizer, and titanium dioxide to obtain a mixture; performing a first calendering on the mixture to obtain a calendered film with a first thickness; adding carbon black to the calendered film with the first thickness and performing a second calendering to obtain a calendered film with a second thickness, and the second thickness is less than the first thickness. In the embodiment of the present invention, during the first calendering process, a relatively thick intermediate calendered film is first formed, and then carbon black is added to the relatively thick calendered film for repeated proofing, thereby obtaining a polyvinyl chloride calendered film with uniform carbon black distribution, reducing the color difference of the black polyvinyl chloride calendered film, making the hue of the black polyvinyl chloride calendered film controllable, improving the appearance quality of the polyvinyl chloride calendered film, and by adding a plasticizer, a stabilizer, and titanium dioxide, the service performance of the polyvinyl chloride calendered film is also improved, and the service life of the polyvinyl chloride calendered film is prolonged. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other embodiments can be obtained based on these drawings.

[0018] Figure 1 It is a flowchart of a preparation method of a polyvinyl chloride calendered film provided by an embodiment of the present invention; Figure 2 It is a flowchart of a preparation method of a polyvinyl chloride calendered film provided by an embodiment of the present invention; Figure 3 It is a flowchart of a preparation method of a polyvinyl chloride calendered film provided by an embodiment of the present invention; Figure 4 It is a detection result diagram obtained by performing color difference detection based on the preparation method of the polyvinyl chloride calendered film provided by an embodiment of the present invention; Figure 5 It is a detection result diagram obtained by performing color difference detection based on the preparation method of the polyvinyl chloride calendered film provided by an embodiment of the present invention; Figure 6 It is a detection result diagram obtained by performing color difference detection based on the preparation method of the polyvinyl chloride calendered film provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] To make the objectives, technical solutions, and advantages of the present invention clearer, the following further elaborates on the embodiments of the present invention in detail with reference to specific embodiments and the accompanying drawings.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs; the terms used in the description of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. For example, the terms such as "length", "width", "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate the orientation or position based on the orientation or position shown in the drawings, which is only for convenience of description and cannot be construed as a limitation to the technical solution of the present invention.

[0021] The terms "comprising" and "having" and any variations thereof in the description and claims of the present invention and the above description of the drawings are intended to cover non-exclusive inclusion; the terms "first", "second", etc. in the description and claims of the present invention or the above drawings are used to distinguish different objects and not to describe a specific order. The meaning of "a plurality" is two or more unless otherwise specifically defined.

[0022] In the description and claims of the present invention and the above description of the drawings, when an element is referred to as being "fixed to" or "mounted on" or "disposed on" or "connected to" another element, it can be directly or indirectly located on that other element. For example, when an element is referred to as being "connected to" another element, it can be directly or indirectly connected to that other element.

[0023] The present invention will be described in detail below with reference to the embodiments and the drawings.

[0024] The first aspect of the embodiments of the present invention provides a method for preparing a polyvinyl chloride calendered film, as Figure 1 shown, the method specifically includes steps S10 to S30.

[0025] S10. Uniformly mix polyvinyl chloride resin, plasticizer, stabilizer and titanium dioxide together to obtain a mixture.

[0026] PVC resin has good mechanical properties and processing properties, is easy to mold, and is easy to be molded by various processing methods such as extrusion, injection molding, calendering, etc. under certain temperature and pressure, and can meet the requirements of different application fields. When preparing a polyvinyl chloride calendered film, by adding various additives such as plasticizer and stabilizer, the performance of the polyvinyl chloride calendered film can be improved, so that the prepared polyvinyl chloride calendered film can adapt to different use environments and functions.

[0027] Titanium dioxide has high hiding power and high refractive index and can strongly scatter or absorb visible light. During the process of preparing a polyvinyl chloride calendered film, by increasing titanium dioxide, the gloss of the prepared polyvinyl chloride calendered film can be improved, the light resistance and heat resistance can be enhanced, and the service life can be extended.

[0028] Plasticizers can weaken the intermolecular attraction of the resin, thereby reducing the melting temperature of the resin and the viscosity during plastic processing. At the same time, the mobility of the resin molecular chains is increased, making the plastic soft and elastic.

[0029] Stabilizers can inhibit the degradation reaction of polyvinyl chloride caused by factors such as heat, light, and oxidation during processing and use, thereby extending the service life of the prepared polyvinyl chloride calendered film.

[0030] S20. Perform the first calendering on the mixture to obtain a calendered film with a first thickness.

[0031] The calendering process is a process in which, under high-temperature conditions, a mixture composed of polyvinyl chloride resin, plasticizer, stabilizer, and titanium dioxide is extruded and extended through the gap between a pair or more pairs of relatively rotating horizontal rollers to form a calendered film with a certain thickness and a smooth surface.

[0032] By using a calender film machine, the first calendering of the mixture can be performed under high-temperature conditions to obtain a calendered film with a first thickness. The high-temperature conditions can be understood as a temperature greater than 150 °C. For example, 160 °C, 170 °C, 180 °C, or 190 °C, etc.

[0033] S30. Add carbon black to the calendered film with the first thickness and perform the second calendering to obtain a calendered film with a second thickness.

[0034] Among them, the second thickness is less than the first thickness. For example, the first thickness can be in the range of 1 cm to 2 cm. For example, the first thickness can be 1.1 cm, 1.2 cm, 1.3 cm, 1.5 cm, 1.6 cm, or 1.8 cm, etc. For example, the second thickness can be in the range of 0.1 to 0.5. For example, the second thickness can be 0.2 cm, 0.3 cm, 0.35 cm, 0.4 cm, or 0.45 cm, etc. It should be understood that the first thickness and the second thickness are not limited to the thicknesses described in the above examples, and can also be other thicknesses, where the second thickness can be determined according to the user's usage requirements, as long as the first thickness is greater than the second thickness.

[0035] The calendered film with the first thickness is calendered by a calender film machine, and carbon black is added and sampled repeatedly during the calendering process until the carbon black is evenly mixed with the calendered film with the first thickness to obtain a calendered film with a second thickness, which is the finally prepared polyvinyl chloride calendered film.

[0036] The polyvinyl chloride calendered film in the embodiments of the present invention is not formed by one-time calendering, but is prepared by a two-stage calendering process. During the first calendering process, a relatively thick intermediate calendered film is first formed, and then carbon black is added to the relatively thick calendered film for repeated proofing, thereby obtaining a polyvinyl chloride calendered film with uniform carbon black distribution, reducing the color difference of the black polyvinyl chloride calendered film, making the hue of the black polyvinyl chloride calendered film controllable, improving the appearance quality of the polyvinyl chloride calendered film, and also improving the service performance of the polyvinyl chloride calendered film and extending the service life of the polyvinyl chloride calendered film by adding plasticizers, stabilizers and titanium dioxide.

[0037] In some embodiments of the present invention, uniformly mixing polyvinyl chloride resin, plasticizer, stabilizer and titanium dioxide may include: mixing polyvinyl chloride resin, plasticizer, stabilizer and titanium dioxide in a ratio of (50~150) g: (26~45) g: (1~5) g: (1~5) g.

[0038] By mixing polyvinyl chloride resin, plasticizer, stabilizer and titanium dioxide in a ratio of (50~150) g: (26~45) g: (1~5) g: (1~5) g to prepare the polyvinyl chloride calendered film, the service performance of the polyvinyl chloride calendered film can be further improved and the service life of the polyvinyl chloride calendered film can be extended.

[0039] Specifically, the addition amount of polyvinyl chloride resin can be 55 g, 60 g, 65 g, 70 g, 75 g, 80 g, 85 g, 90 g, 95 g, 100 g, 105 g, 110 g, 115 g, 120 g, 125 g, 130 g, 135 g or 140 g, etc., and no specific limitation is made here.

[0040] The addition amount of the plasticizer can be 27 g, 28 g, 30 g, 32 g, 35 g, 36 g, 38 g, 40 g, 42 g or 44 g, etc., and no specific limitation is made here.

[0041] The addition amount of the stabilizer can be 1.2 g, 1.5 g, 2 g, 2.3 g, 2.5 g, 2.8 g, 3 g, 3.5 g, 3.8 g, 4 g, 4.3 g, 4.5 g, or 4.8 g, etc., and no specific limitation is made here.

[0042] The addition amount of titanium dioxide can be 1.2 g, 1.5 g, 2 g, 2.3 g, 2.5 g, 2.8 g, 3 g, 3.5 g, 3.8 g, 4 g, 4.3 g, 4.5 g, or 4.8 g, etc., and no specific limitation is made here.

[0043] Preferably, the addition amount of the plasticizer can be 40 g.

[0044] Preferably, the addition amount of the stabilizer can be 3 g.

[0045] Preferably, the addition amount of titanium dioxide can be 3 g.

[0046] Preferably, the addition amount of polyvinyl chloride resin can be 115 g.

[0047] In some embodiments of the present invention, adding carbon black to the calendered film with the first thickness may include: adding (0.05 - 0.3) g of carbon black to the calendered film with the first thickness.

[0048] By adding (0.05 - 0.3) g of carbon black to the calendered film with the first thickness and repeatedly making samples under high - temperature conditions through a calender film machine, a polyvinyl chloride calendered film with uniform carbon black distribution and a black polyvinyl chloride calendered film with better hue can be obtained, which can reduce the color difference of the black polyvinyl chloride calendered film, make the hue of the black polyvinyl chloride calendered film controllable, and improve the appearance quality of the polyvinyl chloride calendered film.

[0049] Specifically, the addition amount of titanium dioxide can be 0.06 g, 0.08 g, 0.09 g, 0.1 g, 0.12 g, 0.15 g, 0.18 g, 0.2 g, 0.22 g, 0.23 g, 0.25 g, 0.26 g, or 0.28 g, etc., which are not specifically limited here. Preferably, the addition amount of carbon black is 0.1 g.

[0050] In some embodiments of the present invention, the plasticizer may include phthalate plasticizers.

[0051] The most commonly used plasticizers are phthalate plasticizers. Phthalate - phthalate esters led by di(2 - ethylhexyl) phthalate (DOP or DEHP) are the most excellent class of monomer plasticizers. They are organic substances that can improve the fluidity of the resin during molding processing and make the products flexible.

[0052] In some embodiments of the present invention, the stabilizer may include lead salt stabilizers and / or metal soap stabilizers.

[0053] The selection of stabilizer varieties is mainly based on the requirements of film stability, processing methods, and transparency. The stabilizer types in the embodiments of the present invention are mainly lead salt stabilizers and metal soap stabilizers. For example, the metal soap stabilizer can be barium / cadmium, barium / cadmium / zinc, barium / lead, etc. Specifically, the stabilizer can be a composite stabilizer of calcium stearate (CaSt) combined with Zn soap or a composite stabilizer of barium stearate (BaSt) combined with Pb and Ca soap.

[0054] In some embodiments of the present invention, the first thickness is in the range of 1 cm to 2 cm.

[0055] In some embodiments of the present invention, the first calendering of the mixture to obtain a calendered film with a first thickness may include: calendering the mixture at 160-200 °C to obtain a calendered film with a first thickness.

[0056] By calendering the mixture at 160-200 °C to obtain a calendered film with a first thickness, and then calendering the calendered film with the first thickness at 160-200 °C, a polyvinyl chloride calendered film with better service performance can be obtained.

[0057] Based on the same inventive concept, an embodiment of the present invention also provides a method for detecting the hue of a polyvinyl chloride calendered film, as Figure 2 shown, the method for detecting the hue of the polyvinyl chloride calendered film includes steps S1 to S5.

[0058] S1. Uniformly mix polyvinyl chloride resin, plasticizer, stabilizer, and titanium dioxide together to obtain a mixture.

[0059] S2. Calender the mixture for the first time to obtain a calendered film with a first thickness.

[0060] S3. Add carbon black to the calendered film with the first thickness and perform a second calendering to obtain a calendered film with a second thickness, where the second thickness is less than the first thickness.

[0061] S4. Cut out a test sample from the calendered film with the second thickness.

[0062] S5. Perform color difference detection on the test sample based on a spectrophotometer.

[0063] In the embodiment of the present invention as Figure 2 shown, by uniformly mixing polyvinyl chloride resin, plasticizer, stabilizer, and titanium dioxide together, a mixture can be obtained. By calendering the mixture for the first time, a calendered film with a first thickness can be obtained. By using a calender to calender the calendered film with the first thickness and adding carbon black to repeatedly sample during the calendering process until the carbon black is uniformly mixed with the calendered film with the first thickness, a calendered film with a second thickness is obtained. Cut several test samples from the prepared calendered film with the second thickness, and perform color difference detection on the several test samples respectively through a spectrophotometer, thereby testing the color difference of the prepared black polyvinyl chloride calendered film. Through the hue detection method of the embodiment of the present invention, the color difference of the prepared black polyvinyl chloride calendered film can be quickly and accurately detected.

[0064] In some embodiments of the present invention, as Figure 3 shown, the method for preparing a polyvinyl chloride calendered film provided by the embodiment of the present invention includes steps S100 to S400.

[0065] S100. Put 50 - 150 g of PVC resin, 26 - 45 g of plasticizer, 1 - 5 g of stabilizer, and 1 - 5 g of titanium dioxide into an automatic mixer and mix evenly.

[0066] S200. Perform the first calendering on the evenly mixed mixture using a calender film machine to prepare a calendered film with the first thickness.

[0067] S300. Perform the second calendering on the calendered film with the first thickness using a calender film machine, and add 0.05 - 0.3 g of carbon black during the second calendering and sample repeatedly until the carbon black is evenly mixed with the calendered film with the first thickness to obtain a calendered film with a thickness of 0.20 mm.

[0068] S400. Take a part of the sample from the calendered film with the second thickness, cut the sample well, and perform color difference detection using a spectrophotometer.

[0069] The following elaborates on the concept of the present invention through specific examples of polyvinyl chloride film preparation. For understanding, the following examples are only used to explain the present invention and are not used to limit the present invention.

[0070] Example 1 Put 115 g of PVC resin, 40 g of dioctyl phthalate, 3 g of calcium stearate, and 3 g of titanium dioxide into an automatic mixer and mix evenly; perform film formation on the evenly mixed mixture using a calender film machine, and add 0.1 g of carbon black and sample repeatedly after the powder sample forms a film until the carbon black is evenly mixed into the calendered film to obtain a black polyvinyl chloride calendered film with a thickness of 0.20 m. The preparation of the entire black polyvinyl chloride calendered film is completed within 5 minutes. Take a part of the sample from the prepared black polyvinyl chloride calendered film, cut the sample well, and perform color difference detection using a spectrophotometer. In this example, 9 samples are selected for the experiment, and 3 repeated experiments are carried out for each, obtaining the detection results as shown in Figure 4 shown.

[0071] From Figure 4 it can be seen that for the same sample, the difference △b value between the detection results of the 3 detections and the b value of the standard sample is within ±0.20.

[0072] Example 2 Put 100 g of PVC resin, 40 g of dioctyl phthalate, 4 g of calcium stearate, and 5 g of titanium dioxide into an automatic mixer and mix evenly; perform film formation on the evenly mixed mixture using a calender film machine, and add 0.1 g of carbon black and sample repeatedly after the powder sample forms a film until the carbon black is evenly mixed into the calendered film to obtain a black polyvinyl chloride calendered film with a thickness of 0.20 m. The preparation of the entire black polyvinyl chloride calendered film is completed within 5 minutes. Take a part of the sample from the prepared black polyvinyl chloride calendered film, cut the sample well, and perform color difference detection using a spectrophotometer. In this example, 11 samples are selected for the experiment, obtaining the results as shown inFigure 5 The detection results shown

[0073] Through Figure 5 It can be seen that the difference Δb values between the detection results of 11 groups of test samples and the b value of the standard sample are all within ±0.20

[0074] Example 3 Put 115 g of PVC resin, different dosages of dioctyl phthalate (26 g, 35 g, 40 g, 45 g), 3 g of calcium stearate, and 3 g of titanium dioxide into an automatic mixer and mix evenly; the evenly mixed mixture is formed into a film by a calender film machine. After the powder sample is formed into a film, 0.1 g of carbon black is added and sampled repeatedly until the carbon black is evenly mixed into the calender film to obtain a black polyvinyl chloride calender film with a thickness of 0.20 m. The preparation of the entire black polyvinyl chloride calender film is completed within 5 minutes. Take a part of the sample from the prepared black polyvinyl chloride calender film. After cutting the sample, perform color difference detection with a spectrophotometer. In this example, 11 samples are selected for the experiment, and the detection results are as shown Figure 6 The detection results shown

[0075] Through Figure 6 It can be seen that in the comparative test of different dosages of dioctyl phthalate for 11 groups of samples, as the dosage of the plasticizer increases, the hue of the PVC calender film begins to tend to be stable; when the dosage of dioctyl phthalate increases to 40 g, the color difference of the PVC calender film is consistent with the trend of 45 g

[0076] The polyvinyl chloride calender film in the embodiment of the present invention is prepared by a secondary calendering process. In the first calendering process, a relatively thick intermediate calender film is first formed, and then carbon black is added to the relatively thick calender film and sampled repeatedly to obtain a polyvinyl chloride calender film with uniform carbon black distribution. Thereby, the color difference of the black polyvinyl chloride calender film is reduced, the hue of the black polyvinyl chloride calender film is controllable, the appearance quality of the polyvinyl chloride calender film is improved, and by adding a plasticizer, a stabilizer, and titanium dioxide, the service performance of the polyvinyl chloride calender film is also improved, and the service life of the polyvinyl chloride calender film is extended

[0077] Based on the same inventive concept, according to another aspect of the present invention, an embodiment of the present invention further provides a polyvinyl chloride calender film, including: polyvinyl chloride resin, plasticizer, stabilizer, titanium dioxide, and carbon black, and the polyvinyl chloride calender film is prepared by the polyvinyl chloride calender film preparation method described in any of the above embodiments

[0078] By adding a plasticizer, a stabilizer, and titanium dioxide, the service performance of the polyvinyl chloride calender film in the embodiment of the present invention is improved, and the service life of the polyvinyl chloride calender film is extended

[0079] In some embodiments of the present invention, the proportions of polyvinyl chloride resin, plasticizer, stabilizer, titanium dioxide, and carbon black in the polyvinyl chloride calendered film are: (50~150) g : (26~45) g : (26~45) g : (26~45) g : (0.05~0.3) g.

[0080] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as within the scope described in this specification.

[0081] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims.

Claims

1. A method for preparing a polyvinyl chloride calendered film, characterized in that, Comprising: Uniformly mix polyvinyl chloride resin, plasticizer, stabilizer and titanium dioxide to obtain a mixture; Perform the first calendering on the mixture to obtain a calendered film with a first thickness; Add carbon black to the calendered film with the first thickness and perform the second calendering to obtain a calendered film with a second thickness, and the second thickness is less than the first thickness.

2. The method for preparing a polyvinyl chloride calendered film according to claim 1, wherein The uniformly mixing of polyvinyl chloride resin, plasticizer, stabilizer and titanium dioxide comprises: Mix polyvinyl chloride resin, plasticizer, stabilizer and titanium dioxide in a ratio of (50 - 150) g : (26 - 45) g : (1 - 5) g : (1 - 5) g.

3. The method for preparing a polyvinyl chloride calendered film according to claim 2, characterized in that, The adding of carbon black to the calendered film with the first thickness comprises: Add (0.05 - 0.3) g of carbon black to the calendered film with the first thickness.

4. The method for preparing a polyvinyl chloride calendered film according to claim 1, wherein, The plasticizer is a phthalate plasticizer.

5. The method for preparing a polyvinyl chloride calendered film according to claim 1, characterized in that, The stabilizer comprises a lead salt stabilizer and / or a metal soap stabilizer.

6. The method for preparing a polyvinyl chloride calendered film according to claim 1, wherein The first thickness is in the range of 1 cm to 2 cm.

7. The method for preparing a polyvinyl chloride calendered film according to claim 1, characterized in that, Performing the first calendering on the mixture to obtain a calendered film with a first thickness comprises: At 160 - 200 °C, perform the first calendering on the mixture to obtain a calendered film with a first thickness.

8. A method for detecting the hue of a polyvinyl chloride calendered film, characterized in that, Comprising: Uniformly mix polyvinyl chloride resin, plasticizer, stabilizer and titanium dioxide to obtain a mixture; Perform the first calendering on the mixture to obtain a calendered film with a first thickness; Add carbon black to the calendered film with the first thickness and perform the second calendering to obtain a calendered film with a second thickness, and the second thickness is less than the first thickness; Cut out a test sample from the calendered film with the second thickness; Based on a spectrophotometer colorimeter, perform color difference detection on the test sample.

9. A polyvinyl chloride calendered film, characterized in that, Comprising: Polyvinyl chloride resin, plasticizer, stabilizer, titanium dioxide and carbon black, and the polyvinyl chloride calendered film is prepared by the polyvinyl chloride calendered film preparation method according to any one of claims 1 - 8.

10. The polyvinyl chloride calendered film according to claim 9, wherein, The ratio of the polyvinyl chloride resin, plasticizer, stabilizer, titanium dioxide and carbon black is: (50 - 150) g : (26 - 45) g : (1 - 5) g : (1 - 5) g : (0.05 - 0.3) g.

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