Sand streak wax as well as preparation method and application thereof

Abstract

The invention belongs to the field of coating additives, and particularly relates to sand streak wax as well as a preparation method and application thereof. The sand streak wax is of a multi-layer structure and sequentially comprises a high-melting-point wax layer, a middle-melting-point wax layer and a low-melting-point wax layer from inside to outside, wherein the melting point ranges of the high-melting-point wax layer, the middle-melting-point wax layer and the low-melting-point wax layer are 200-350 DEG C, 120-200 DEG C and 50-120 DEG Wherein the high-melting-point wax layer, the middle-melting-point wax layer and the low-melting-point wax layer are combined through melting interfaces. By developing the sand streak wax with a high / medium / low melting point three-layer structure, the stable sand streak effect of a single additive in a wide addition range of 1%-10% is achieved, the texture roughness can be controlled by adjusting the curing temperature, and meanwhile the technical problems that a traditional sand streak coating is complex in formula design and narrow in construction window are solved.

Description

Technical Field

[0001] The invention belongs to the field of coating additives, and particularly relates to a sand texture wax and a preparation method and application thereof. Background Art

[0002] A texturizing agent is an additive that imparts a uniform surface texture, gloss, and color to a coating surface. Insoluble or incompatible additives are often added to control the powder's particle size, melt viscosity, and surface tension to achieve the desired texture. Textured coatings are a general term for various types, including sand-textured, wrinkle-textured, and water-textured.

[0003] Industrial coatings with a sand-like texture, known as sand grains, are widely used in home appliances, furniture, building materials, the automotive industry, and other metal products due to their high decorative value, their ability to conceal surface imperfections and enhance product appearance. These coatings are typically prepared by adding a low-polarity graining agent to industrial coatings. During the melting, leveling, and curing processes, the high-surface-tension binder encapsulates the low-surface-tension graining agent, creating a uniformly distributed sand-like appearance on the coating.

[0004] Currently, one of the methods for preparing sand-textured coatings is to add incompatible substances. For example, patent CN108359033 prepares a high molecular weight polyethylene sand-textured wax, and patent CN107532014 uses polytetrafluoroethylene as a texturing additive. However, the existing technology has the following limitations: in order to obtain different sand-textured effects, it is necessary to make specific selections based on the main material of the coating, the characteristics of the formula materials, the thickness of the coating, etc., and to precisely control the amount of sand-textured agent added to ensure that a stable sand-textured effect can be formed without affecting other properties of the coating. This increases the complexity of the formula design and requires strict control of construction conditions, such as the spraying environment, curing temperature and time, to ensure that incompatible substances can function correctly and form the desired sand-textured effect. These limitations lead to problems such as a narrow application range and low yield in existing sand-textured coatings. Summary of the Invention

[0005] Technical issues

[0006] The present invention aims to provide a sand-textured wax which can solve the problems of complex formula design and narrow construction window of traditional sand-textured coatings.

[0007] Technical Solution

[0008] The first aspect of the present invention provides a sand pattern wax, which is a multi-layer structure and sequentially includes from the inside to the outside: a high melting point wax layer, a medium melting point wax layer, and a low melting point wax layer with melting point ranges of 200 - 350 °C, 120 - 200 °C, and 50 - 120 °C respectively; wherein, the high melting point wax layer, the medium melting point wax layer, and the low melting point wax layer are combined through a molten interface.

[0009] In some embodiments, the high melting point wax layer uses polytetrafluoroethylene wax; the medium melting point wax layer uses any one of high-density oxidized polyethylene wax, polypropylene wax, polyamide wax, or oxidized polyethylene wax; the low melting point wax layer uses any one of carnauba wax, low-density oxidized polyethylene wax, paraffin wax, microcrystalline wax, beeswax, montan wax, or Fischer-Tropsch wax.

[0010] In some embodiments, the thicknesses of the high melting point wax layer, the medium melting point wax layer, and the low melting point wax layer respectively account for 20% - 30%, 50% - 60%, and 10% - 20% of the total thickness of the sand pattern wax. The thicknesses of the high melting point wax layer, the medium melting point wax layer, and the low melting point wax layer can be selected according to the desired effect of the sand pattern coating.

[0011] In some embodiments, the DV90 particle size of the sand pattern wax is 20 - 45 μm.

[0012] In some embodiments, the difference between the melting point of the medium melting point wax layer and the melting point of the high melting point wax layer is ≥ 50 °C, and the difference between the melting point of the low melting point wax layer and the melting point of the medium melting point wax layer is ≥ 30 °C.

[0013] The second aspect of the present invention provides a method for preparing the sand pattern wax described in any one of the above, including the following steps: S1. Prepare the first wax micro-powder from the high melting point wax raw material through supercritical CO2 melt spraying method; S2. Mix and knead the medium melting point wax raw material and the first wax micro-powder evenly through a twin-screw extruder, press the extruded sheet into a sheet, and then prepare the second wax micro-powder through supercritical CO2 melt spraying method; S3. Mix and knead the low melting point wax raw material and the second wax micro-powder evenly through a twin-screw extruder, press the extruded sheet into a sheet, and then prepare the third wax micro-powder through supercritical CO2 melt spraying method to obtain the sand pattern wax.

[0014] In some embodiments, the DV90 particle size of the first wax micro-powder is 5 - 1OKm; the DV90 particle size of the second wax micro-powder is 15 - 35 μm.

[0015] In some embodiments, in step S2, the kneading temperature is controlled in the range of increasing by 15 - 25 °C based on the melting point of the medium melting point wax layer; in step S3, the kneading temperature is controlled in the range of increasing by 10 - 20 °C based on the melting point of the low melting point wax layer.

[0016] The third aspect of the present invention provides an application of the sand pattern wax described in any one of the above in industrial coatings.

[0017] The fourth aspect of the present invention provides a coating composition containing the sand pattern wax described in any one of the above.

[0018] Technical effects

[0019] 1. The sand pattern wax prepared by the preparation method provided by the present invention has high versatility, can be adapted to a variety of coating main materials and formulation systems, and there is no need for specific selection for different materials, significantly reducing the complexity of formula design.

[0020] 2. The present invention simplifies the control of the addition amount, and a stable sand pattern effect can be formed within a relatively wide addition amount range (such as 1% - 10%), avoiding problems such as uneven texture or performance decline caused by deviation of the addition amount.

[0021] 3. The construction conditions of the present invention have strong fault tolerance. Different sand pattern effects can be achieved directly by adjusting the curing conditions. The construction sensitivity is reduced, allowing a looser process window and improving production stability.

[0022] 4. Adding the sand pattern agent of the present invention can achieve the effects of both the sand pattern agent and the wax additive in traditional sand pattern coatings. Description of the drawings

[0023] Figure 1 It is a schematic diagram of the sand pattern wax structure. Detailed implementation manners

[0024] For the convenience of reviewing the technical solutions of the application, the following first gives a general description and definition of the terms and expressions involved in the present application.

[0025] The term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0026] The particle size Dv90 refers to the particle size value corresponding to the cumulative distribution percentage reaching 90% from small to large in the particle size distribution.

[0027] The hardness of a pencil is soft for B, hard for H, and medium for HB. For the hardness H1 - H6, the larger the number, the stronger the hardness and the lighter the color. For the softness B1 - B6, the larger the number, the greater the softness and the darker the color.

[0028] The density of high-density oxidized polyethylene wax is 0.94 - 0.98 g / cm3 .

[0029] The density of the low-density oxidized polyethylene wax is 0.91 - 0.93 g / cm 3 .

[0030] The test method for the roughness of the coating described in the present invention is carried out with reference to JIS B 0601-2013.

[0031] The test method for the pencil hardness of the coating is carried out with reference to GB / T 6739-2022.

[0032] The test method for the impact performance of the coating is determined with reference to T / GDTL 004-2019.

[0033] Process conditions for preparing wax fine powder by supercritical CO2 melt spraying: According to the melting points of different waxes, select appropriate temperatures and pressures, completely dissolve the wax raw materials in supercritical CO2, and then quickly depressurize and spray through a nozzle to obtain fine powder.

[0034] In each group of comparative experiments provided in this application, unless otherwise specified, except for the differences pointed out in each group, other experimental conditions, materials, etc. are kept consistent for comparability.

[0035] The reagents and instrument equipment used in the examples of the present invention can be purchased from the market without detailed description.

[0036] The following further describes a sand pattern wax and its preparation method and application provided in this application.

[0037] Preparation of sand pattern wax in Example 1

[0038] The structure of the sand pattern wax is as Figure 1 shown. The preparation method of the sand pattern wax includes the following steps:

[0039] S1. Prepare the first wax fine powder from the high-melting-point wax raw material by the supercritical CO2 melt spraying method;

[0040] S2. Mix the medium-melting-point wax raw material and the first wax fine powder evenly by a twin-screw extruder, press the extruded sheet material, and then prepare the second wax fine powder by the supercritical CO2 melt spraying method;

[0041] S3. Mix the low-melting-point wax raw material and the second wax fine powder evenly by a twin-screw extruder, press the extruded sheet material, and then prepare the third wax fine powder by the supercritical CO2 melt spraying method to obtain the sand pattern wax.

[0042] Among them, the high melting point wax in step S1 is polytetrafluoroethylene wax (melting point 230°C), and the particle size DV90 of the first wax micropowder detected by a laser particle size analyzer is 8 μm; the medium melting point wax in step S2 is high-density oxidized polyethylene wax (melting point 140°C), and the particle size DV90 of the second wax micropowder detected by a laser particle size analyzer is 29.5 μm; the low melting point wax in step S3 is carnauba wax (melting point 85°C), and the particle size DV90 of the third wax micropowder detected by a laser particle size analyzer is 37 μm.

[0043] Preparation of sand pattern wax in Example 2

[0044] The difference from Example 1 is that: the high melting point wax in step S1 is polytetrafluoroethylene wax (melting point 230°C), the particle size DV90 of the first wax micropowder detected by a laser particle size analyzer is 8 μm, the medium melting point wax in step S2 is high-density oxidized polyethylene wax (melting point 140°C), the particle size DV90 of the second wax micropowder detected by a laser particle size analyzer is 23 μm, the low melting point wax in step S3 is carnauba wax (melting point 85°C), and the particle size DV90 of the third wax micropowder detected by a laser particle size analyzer is 28 μm.

[0045] Preparation of sand pattern wax in Example 3

[0046] The difference from Example 1 is that: the high melting point wax in step S1 is polytetrafluoroethylene wax (melting point 230°C), the particle size DV90 of the first wax micropowder detected by a laser particle size analyzer is 8 μm, the medium melting point wax in step S2 is high-density oxidized polyethylene wax (melting point 140°C), the particle size DV90 of the second wax micropowder detected by a laser particle size analyzer is 24 μm, the low melting point wax in step S3 is carnauba wax (melting point 85°C), and the particle size DV90 of the third wax micropowder detected by a laser particle size analyzer is 28 μm.

[0047] Preparation of sand pattern wax in Example 4

[0048] The difference from Example 1 is that: the high melting point wax in step S1 is polytetrafluoroethylene wax (melting point 230°C), the particle size DV90 of the first wax micropowder detected by a laser particle size analyzer is 8 μm, the medium melting point wax in step S2 is high-density oxidized polyethylene wax (melting point 140°C), the particle size DV90 of the second wax micropowder detected by a laser particle size analyzer is 24 μm, the low melting point wax in step S3 is low-density oxidized polyethylene wax (melting point 100°C), and the particle size DV90 of the third wax micropowder detected by a laser particle size analyzer is 28 μm.

[0049] Preparation of sand pattern wax in Example 5

[0050] The differences from Example 1 are as follows: The high-melting-point wax in step S1 is polytetrafluoroethylene wax (melting point 210°C), and the DV90 of the particle size of the first wax fine powder detected by a laser particle size analyzer is 8 μm. The medium-melting-point wax in step S2 is polypropylene wax (melting point 150°C), and the DV90 of the particle size of the second wax fine powder detected by a laser particle size analyzer is 24 μm. The low-melting-point wax in step S3 is low-density oxidized polyethylene wax (melting point 110°C), and the DV90 of the particle size of the third wax fine powder detected by a laser particle size analyzer is 28 μm.

[0051] Preparation of Sand Pattern Wax in Example 6

[0052] The differences from Example 1 are as follows: The high-melting-point wax in step S1 is polytetrafluoroethylene wax (melting point 210°C), and the DV90 of the particle size of the first wax fine powder detected by a laser particle size analyzer is 8 μm. The medium-melting-point wax in step S2 is polypropylene wax (melting point 140°C), and the DV90 of the particle size of the second wax fine powder detected by a laser particle size analyzer is 24 μm. The low-melting-point wax in step S3 is polyethylene wax (melting point 110°C), and the DV90 of the particle size of the third wax fine powder detected by a laser particle size analyzer is 28 μm.

[0053] Preparation of Sand Pattern Wax in Example 7

[0054] The differences from Example 1 are as follows: The high-melting-point wax in step S1 is polytetrafluoroethylene wax (melting point 210°C), and the DV90 of the particle size of the first wax fine powder detected by a laser particle size analyzer is 8 μm. The medium-melting-point wax in step S2 is polypropylene wax (melting point 14°0C), and the DV90 of the particle size of the second wax fine powder detected by a laser particle size analyzer is 24 μm. The low-melting-point wax in step S3 is carnauba wax (melting point 110°C), and the DV90 of the particle size of the third wax fine powder detected by a laser particle size analyzer is 28 μm.

[0055] Preparation of Sand Pattern Wax in Example 8

[0056] The differences from Example 1 are as follows: The high-melting-point wax in step S1 is polytetrafluoroethylene wax (melting point 200°C), and the DV90 of the particle size of the first wax fine powder detected by a laser particle size analyzer is 8 μm. The medium-melting-point wax in step S2 is polyamide wax (melting point 150°C), and the DV90 of the particle size of the second wax fine powder detected by a laser particle size analyzer is 24 μm. The low-melting-point wax in step S3 is carnauba wax (melting point 80°C), and the DV90 of the particle size of the third wax fine powder detected by a laser particle size analyzer is 28 μm.

[0057] Preparation of Sand Pattern Wax in Example 9

[0058] The differences from Example 1 are as follows: The high melting point wax in step S1 is polytetrafluoroethylene wax (melting point 200 °C). The particle size DV90 of the first wax micropowder is 8 μm detected by a laser particle size analyzer. The medium melting point wax in step S2 is high density oxidized polyethylene wax (melting point 130 °C). The particle size DV90 of the second wax micropowder is 24 μm detected by a laser particle size analyzer. The low melting point wax in step S3 is polyethylene wax (melting point 100 °C). The particle size DV90 of the third wax micropowder is 28 μm detected by a laser particle size analyzer.

[0059] Comparative Example 1

[0060] The raw material is polytetrafluoroethylene wax (melting point 230 °C), which is made into wax micropowder. The particle size DV90 of the wax micropowder is 28 μm detected by a laser particle size analyzer.

[0061] Comparative Example 2

[0062] The raw material is polypropylene wax (melting point 170 °C), which is made into wax micropowder. The particle size DV90 of the wax micropowder is 28 μm detected by a laser particle size analyzer.

[0063] Comparative Example 3

[0064] The raw material is polyethylene wax (melting point 120 °C), which is made into wax micropowder. The particle size DV90 of the wax micropowder is 28 μm detected by a laser particle size analyzer.

[0065] Comparative Example 4

[0066] The high melting point wax in step S1 is polytetrafluoroethylene wax (melting point 230 °C). The particle size DV90 of S1 is 8 μm detected by a laser particle size analyzer. The medium melting point wax in step S2 is polyamide wax (melting point 150 °C). The particle size DV90 of the second wax micropowder is 28 μm detected by a laser particle size analyzer.

[0067] Comparative Example 5

[0068] The high melting point wax in step S1 is polytetrafluoroethylene wax (melting point 230 °C). The particle size DV90 of S1 is 8 μm detected by a laser particle size analyzer. There is no substance in the medium melting point wax layer in step S2. The low melting point wax in step S3 is polyethylene wax (melting point 120 °C). The particle size DV90 of the third wax micropowder is 28 μm detected by a laser particle size analyzer.

[0069] Comparative Example 6

[0070] The high melting point wax in step S1 is polytetrafluoroethylene wax (melting point 230 °C). The particle size DV90 of S1 is 8 μm detected by a laser particle size analyzer.

[0071] The types and parameters of the raw materials in Examples 1-9 and Comparative Examples 1-6 are shown in Table 1.

[0072] Table 1 Types and parameters of sand texture wax raw materials

[0073]

[0074] Note: The particle size mentioned above refers to the particle size of the first wax powder, the second wax powder and the graining wax respectively prepared in the following steps.

[0075] First, in order to test the application of the graining wax prepared in the embodiments and comparative examples of the present invention in actual industrial coatings, the graining wax prepared in Examples 1-9 and Comparative Examples 1-6 was applied to a conventional industrial coating (coating system 1) to test the coating performance. As shown in Examples 10-15. Then, in order to prove that the graining wax prepared by the present invention can be adapted to a variety of coating main materials and formulation systems, the same batch of graining wax prepared in this application (Example 5) was applied to different industrial coatings (coating systems 1-3), and compared with coating systems 4 and 6 containing graining agents and coating system 5 containing wax additives (low-density oxidized polyethylene wax powder), as shown in Example 16. The specific components of coating systems 1-6 are shown in Table 2.

[0076] Table 2 Composition of different coating systems

[0077]

[0078] Example 10 Application of Sand Texture Wax in Industrial Coatings

[0079] The texture waxes of Examples 1-9 and Comparative Examples 1-6 were taken, with the texture wax accounting for 5% by mass of the total coating system. After being uniformly mixed with the other components in Coating System 1, an appropriate amount of deionized water was added to dilute to a suitable viscosity and then sprayed. After leveling for 15 minutes, the coatings were baked at 80°C for 60 minutes. The roughness, pencil hardness, and impact resistance of the coatings were tested, as shown in Table 2.

[0080] Table 3 Coating performance test data of sand texture wax at 5% addition under 80℃ curing conditions

[0081]

[0082]

[0083] Example 11 Application of Sand Texture Wax in Industrial Coatings

[0084] The grain waxes of Examples 1-9 and Comparative Examples 1-6 were taken, with the grain wax accounting for 5% by mass of the total coating system. After being uniformly mixed with the other components of coating system 1, an appropriate amount of deionized water was added to dilute to a suitable viscosity and then sprayed. After leveling for 15 minutes, the coating was baked at 130°C for 15 minutes. The roughness, pencil hardness and impact resistance of the coating were tested, as shown in Table 3.

[0085] Table 4 Coating performance test data when the addition amount of sand pattern wax is 5% under the curing condition of 130°C

[0086]

[0087] Application of sand pattern wax in industrial coatings in Example 12

[0088] Respectively take the sand pattern waxes of Examples 1-9 and Comparative Examples 1-6. The mass percentage of the sand pattern wax in the total coating system is 5%. After mixing evenly with other components of Coating System 1, add an appropriate amount of deionized water to dilute to a suitable viscosity and then spray for construction. After leveling for 15 minutes, bake at 185°C for 5 minutes, and test the roughness, pencil hardness and impact resistance of the coating, as shown in Table 4.

[0089] Table 5 Coating performance test data when the addition amount of sand pattern wax is 5% under the curing condition of 185°C

[0090]

[0091]

[0092] Application of sand pattern wax in industrial coatings in Example 13

[0093] Respectively take the sand pattern waxes of Examples 1-9 and Comparative Examples 1-6. The mass percentage of the sand pattern wax in the total coating system is 5%. After mixing evenly with other components of Coating System 1, add an appropriate amount of deionized water to dilute to a suitable viscosity and then spray for construction. After leveling for 15 minutes, bake at 240°C for 5 minutes, and test the roughness, pencil hardness and impact resistance of the coating, as shown in Table 5.

[0094] Table 6 Coating performance test data when the addition amount of sand pattern wax is 5% under the curing condition of 240°C

[0095]

[0096] Application of sand pattern wax in industrial coatings in Example 14

[0097] Respectively take the sand pattern waxes of Examples 1-9 and Comparative Examples 1-6. The mass percentage of the sand pattern wax in the total coating system is 1%. After mixing evenly with the other remaining components of Coating System 1, add an appropriate amount of deionized water to dilute to a suitable viscosity and then spray for construction. After leveling for 15 minutes, bake at 130°C for 15 minutes, and test the roughness, pencil hardness and impact resistance of the coating, as shown in Table 6.

[0098] Table 7 Coating performance test data when the addition amount of sand pattern wax is 1% under the curing condition of 130°C

[0099]

[0100]

[0101] Example 15 Application of Sand Pattern Wax in Industrial Coatings

[0102] Take the sand pattern waxes of Examples 1-9 and Comparative Examples 1-6 respectively. The mass percentage of the sand pattern wax in the total coating system is 10%. After being mixed evenly with the other components of Coating System 1, an appropriate amount of deionized water is added to dilute it to a suitable viscosity, and then it is spray-coated. After leveling for 15 min, it is baked at 130 °C for 15 min. The roughness, pencil hardness, and impact resistance of the coating are tested, as shown in Table 7.

[0103] Table 8 Test Data of Coating Performance under the Curing Condition of 130 °C with 10% Sand Pattern Wax Added

[0104]

[0105] It can be seen from the coating performance test data of Examples 1-9 and Comparative Examples 1-6 recorded in Table 2 and Table 7 that the sand pattern wax of the present invention can form a stable sand pattern effect within the range of 1% to 10% addition amount. Among them, the comprehensive performance is the best when the addition amount is 5%: the pencil hardness ≥ 2H (4H in some working conditions), and the positive impact strength ≥ 50 cm passes; although the roughness is slightly lower at a low addition amount (1%), the hardness and impact performance remain good; no uneven texture or performance decline occurs at a high addition amount (10%).

[0106] In addition, it can also be seen from the table that when the curing temperature is lower than the melting point of the low-melting wax layer (such as 80 °C), the coating roughness is the highest (Ra 12.34-22.16 μm), presenting a rough sand pattern; when it is between the melting points of the low-melting and medium-melting wax layers (such as 130 °C), the roughness drops to Ra 5.94-14.37 μm, forming a medium sand pattern; when it is between the melting points of the medium-melting and high-melting wax layers (such as 185 °C), the roughness drops to Ra 1.99-2.77 μm, presenting a delicate sand pattern; when it is higher than the melting point of the high-melting wax layer (such as 240 °C), the roughness is the lowest (Ra 0.51-0.98 μm), presenting an extremely delicate sand pattern or no clear particle texture. This shows that the present invention can realize the regulation of the full-gradient sand pattern effect from rough to extremely delicate by precisely controlling the relative relationship between the curing temperature and the melting points of each layer of wax. Compared with the comparative examples (single wax layer or lack of intermediate layer), the sand pattern wax with a three-layer structure designed by the present invention has significant advantages: the roughness of the three-layer sand pattern wax of the examples is more uniform under the same conditions, and the pencil hardness and impact resistance are better, reflecting the improvement of the comprehensive performance of the coating by the multi-layer melting point gradient design.

[0107] Example 16 Application of Sand Pattern Wax in Various Industrial Coating Systems

[0108] Take the sand pattern wax of Example 5 and mix it evenly with other components in Coatings 1-3 respectively. Add appropriate deionized water to dilute the coating systems 1-3 mixed with the sand pattern wax of the present invention and the comparative coating systems 4-6 to a suitable viscosity, then spray and construct. After leveling for 15 minutes, bake at 130 °C for 15 minutes, and test the roughness, pencil hardness and impact resistance of the coating, as shown in Table 8.

[0109] Table 9 Test data of coating properties of sand pattern wax added under the curing condition of 130 °C for different systems

[0110]

[0111] The data in Table 9 show that when the sand pattern wax of the present invention is applied to different coating systems, under the curing condition of 130 °C, each film thickness shows an appropriate medium sand pattern effect (Ra 7.2-8.5 μm), as well as excellent high hardness (3H) and impact resistance (positive impact passing), which are significantly better than the traditional sand pattern agent system (coating system 6). Although the coating system 4 and the coating system 3 have comparable effects in the tests of roughness, pencil hardness and impact performance, through visual observation, the film appearance of the coating system 3 is more delicate and uniform than that of the coating system 4. It shows that the sand pattern wax of the present invention can replace the traditional sand pattern agent (coating systems 4, 6) or wax additive (coating system 5), and has broad applicability.

[0112] The above specific embodiments have further detailed the purpose, technical solution and beneficial effects of the present application. It should be understood that the above are only the specific embodiments of the present application and are not used to limit the protection scope of the present application. Any modifications, equivalent replacements, improvements, etc. made on the basis of the technical solution of the present application shall be included in the protection scope of the present application.

Claims

1. A sand pattern wax, characterized in that, It is a multi-layer structure, which successively includes from the inside to the outside: a high-melting-point wax layer, a medium-melting-point wax layer, and a low-melting-point wax layer with melting ranges of 200 - 350 °C, 120 - 200 °C, and 50 - 120 °C respectively; wherein, the high-melting-point wax layer, the medium-melting-point wax layer, and the low-melting-point wax layer are combined through a molten interface.

2. The sand pattern wax according to claim 1, characterized in that, The high-melting-point wax layer uses polytetrafluoroethylene wax; the medium-melting-point wax layer uses any one of high-density oxidized polyethylene wax, polypropylene wax, polyamide wax, or oxidized polyethylene wax; the low-melting-point wax layer uses any one of carnauba wax, low-density oxidized polyethylene wax, paraffin wax, microcrystalline wax, beeswax, montan wax, or Fischer-Tropsch wax.

3. The sand pattern wax according to claim 1, characterized in that, The thicknesses of the high-melting-point wax layer, the medium-melting-point wax layer, and the low-melting-point wax layer respectively account for 20% - 30%, 50% - 60%, and 10% - 20% of the total thickness of the sand pattern wax.

4. The sand pattern wax according to claim 1, characterized in that, The DV90 of the particle size of the sand pattern wax is 20 - 45 μm.

5. The sand pattern wax according to claim 1, characterized in that, The difference between the melting point of the medium-melting-point wax layer and the melting point of the high-melting-point wax layer is ≥50 °C, and the difference between the melting point of the low-melting-point wax layer and the melting point of the medium-melting-point wax layer is ≥30 °C.

6. A method for preparing the sand pattern wax according to any one of claims 1-5, characterized in that, It includes the following steps: S1. Prepare the first wax micropowder from the high-melting-point wax raw material by the supercritical CO2 melting spray method; S2. Mix the medium-melting-point wax raw material and the first wax micropowder evenly through a twin-screw extruder, press the extruded sheet material, and then prepare the second wax micropowder by the supercritical CO2 melting spray method; S3. Mix the low-melting-point wax raw material and the second wax micropowder evenly through a twin-screw extruder, press the extruded sheet material, and then prepare the third wax micropowder by the supercritical CO2 melting spray method to obtain the sand pattern wax.

7. The method according to claim 6, characterized in that, The DV90 of the particle size of the first wax micropowder is 5 - 10 μm; the DV90 of the particle size of the second wax micropowder is 15 - 35 μm.

8. The method according to claim 6, wherein In step S2, the mixing temperature is controlled within the range of increasing 15 - 25 °C based on the melting point of the medium-melting-point wax layer; in step S3, the mixing temperature is controlled within the range of increasing 10 - 20 °C based on the melting point of the low-melting-point wax layer.

9. The application of the sand pattern wax according to any one of claims 1 - 4 in industrial coatings.

10. A coating composition containing the sand pattern wax according to any one of claims 1 - 4.

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