Novel color-developing light-transmitting polypropylene composite material with high light transmission, high tinting strength and high paint adhesion and preparation method of novel color-developing light-transmitting polypropylene composite material

Abstract

The invention discloses a color-developing light-transmitting polypropylene composite material with high light transmission, high tinting strength and high paint adhesion and a preparation method thereof. The color-developing light-transmitting polypropylene composite material is prepared from the following raw materials in percentage by weight: 57 to 85 percent of polypropylene resin, 5 to 20 percent of high-light-transmitting filler, 10 to 20 percent of benzene sulfonate grafted SEBS polymer, 0.05 to 0.5 percent of anionic organic dye, 0.1 to 1 percent of antioxidant and 0.2 to 2 percent of other auxiliaries. Through molecular structure design, the benzene sulfonate grafted SEBS polymer with a specific cationic structure is prepared, the polymer can generate charge neutralization with anionic organic dye, molecular-level dispersion and anchoring of the dye are realized, and the molecular weight of the dye is reduced. The problems of poor dispersibility, poor coloring fastness, easy aging migration and the like of the dye in a light-transmitting polypropylene matrix are fundamentally solved, and a composite material system is endowed with a bright color effect while realizing high light transmission and high tinting strength.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials and their processing technology, specifically relating to a functionalized polypropylene composite material with excellent optical properties, color development properties and surface coating properties, and its preparation process. Background Technology

[0002] Polypropylene is widely used in the automotive industry due to its excellent comprehensive properties, good processing performance, and low cost. As automotive design moves towards intelligence and personalization, the demand for luminous exterior parts with light transmission capabilities (such as luminous grilles, light-transmitting bumpers, and light-transmitting trim strips) is becoming increasingly urgent. Color-transmitting polypropylene composites, due to their combination of light transmission and decorative color, have become a popular material for automotive luminous parts, especially luminous bumper parts that integrate car logos and other patterns. This requires polypropylene materials not only to have high light transmittance to achieve backlight display effects, but also to have vibrant and stable colors, as well as excellent paint adhesion to ensure appearance quality and durability.

[0003] Currently, existing color-transmitting and light-transmitting polypropylene material formulations mainly consist of high-transmittance polypropylene, high-transmittance fillers, high-transmittance toughening agents, and colorants. Regarding colorant selection, existing technologies use conventional pigments. While this achieves basic coloring, the pigment particles tend to agglomerate within the system and have strong light-blocking properties, significantly reducing the light transmittance of the composite material. Furthermore, it is difficult to achieve vibrant and saturated colors, failing to meet the appearance requirements of high-end products. For example, CN119875241A discloses a high-transmittance polypropylene composition with controllable light transmittance, color development, and uniformity. This composition uses micro-nano colorant pigments combined with whiskers and hollow glass microspheres to enhance light transmittance. However, the conventional inorganic pigments used have inherent defects; to ensure color development, the amount added needs to be increased, leading to a significant decrease in material transmittance and difficulty in achieving highly saturated, vibrant colors. CN112662078A discloses a dark-colored, near-infrared transparent polypropylene composite. By adding nucleating agents and phthalocyanine pigments, it reduces the refraction and reflection of visible and near-infrared light waves, achieving high light transmittance. However, this technology only focuses on infrared light transmittance and does not solve the problems of vibrant coloring and paint adhesion in the visible light region.

[0004] Another coloring solution is to use dye pigments, which can solve the problem of color vibrancy. However, its application in translucent polypropylene composites has several drawbacks: First, dyes are ionic organic pigments, which have poor compatibility with the non-polar polypropylene matrix and conventional toughening agents, resulting in poor dispersibility and defects such as color spots and streaks. Second, dye pigments have poor color fastness and are prone to aging migration during long-term use, affecting the product's service life and appearance stability. Third, these dye pigments reduce the surface tension of the composite material, leading to problems such as poor adhesion and easy peeling during subsequent paint coating, limiting the material's application in scenarios requiring surface coating. Currently, there are no reported technical solutions for the application of dyes in translucent polypropylene materials.

[0005] In summary, current technologies lack an effective solution that can synergistically address a series of interconnected and contradictory technical problems at the molecular level, namely, high light transmittance, vibrant coloring, dye migration resistance, and high paint adhesion. Therefore, developing an innovative material system to fundamentally overcome the limitations of existing technologies has significant industrial and theoretical value. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing color-transparent polypropylene materials and provide a color-transparent polypropylene composite material with high light transmittance, high coloring strength, and high paint adhesion, as well as its preparation method, to solve the above-mentioned problems of the prior art.

[0007] To achieve the above objectives, this invention proposes a novel material design approach. Through an innovative solvent-based "sulfonation-neutralization" process, the benzene rings on the styrene blocks of the SEBS molecular chain are selectively sulfonated to generate sulfonic acid groups. These groups are then further neutralized to convert to sulfonates, thus preparing a novel, highly polar benzenesulfonate-grafted SEBS polymer with cationic properties. The cationic sulfonate groups (-SO3) on the polymer molecular chain... - M + Through strong electrostatic interactions, it can form stable ion pairs with anionic dye molecules, achieving molecular-level fixation of the dye and effectively preventing its migration. Simultaneously, the introduction of the strongly polar sulfonate groups significantly increases the surface tension of the composite material, providing an excellent wetting and adhesion substrate for paint, thereby improving paint adhesion.

[0008] To achieve the above objectives, the present invention specifically adopts the following technical solution:

[0009] A novel color-transmitting and light-transmitting polypropylene composite material with high light transmittance, high tinting strength, and high paint adhesion, comprising the following raw materials in parts by weight:

[0010]

[0011] In the polypropylene composite material system to which this invention applies,

[0012] The polypropylene resin is a random polypropylene resin with a light transmittance of ≥65% at a thickness of 3 mm and a melt flow rate of 1–30 g / 10 min at 230 °C and a load of 2.16 kg. Preferably, the melt flow rate of the polypropylene resin is 10–30 g / 10 min.

[0013] The principle of the benzenesulfonate-grafted SEBS polymer is as follows: using acetylsulphate as a controllable sulfonating agent, selective electrophilic substitution of polystyrene blocks in the SEBS molecular chain is performed via solution method, followed by alkaline neutralization and other techniques to construct a polymer with stable polar sulfonate side chains; the process flow is as follows. Figure 1 As shown.

[0014] The specific preparation steps of the benzenesulfonate-grafted SEBS polymer are as follows:

[0015] (1) Sulfonation reaction: Under an inert atmosphere and with continuous stirring, SEBS is dissolved in an aprotic organic solvent to form a solution with a mass-volume concentration of 5% to 15%, and the system temperature is controlled at 0 to 5°C; then, the sulfonating reagent acetylsulphate is slowly added dropwise, and the addition time is controlled at 30 to 60 minutes. The molar ratio of acetylsulphate to styrene structural units in SEBS is (0.1 to 0.5):1; after the addition is complete, the reaction is carried out at 20 to 40°C for 1 to 4 hours to obtain the sulfonated intermediate.

[0016] The main chemical process of the sulfonation reaction is represented by the following general formula:

[0017] Polymer -Ph-H + CH3C(O)OSO3H → Polymer -Ph-SO3H + CH3COOH

[0018] (Where, Ph represents a benzene ring)

[0019] (2) Salt formation reaction: Add a cationic reagent to the reaction system obtained in step (1) and carry out a neutralization reaction at 30-60°C for 1-3 hours to convert the sulfonic acid group into a sulfonate group; after the reaction is completed, the final product is obtained by non-solvent precipitation, separation, washing and vacuum drying.

[0020] The main chemical process of the salt-forming reaction is represented by the following general formula:

[0021] Polymer -Ph-SO3H+M(OH) x →polymer-Ph-SO3M+H2O

[0022] (Among them, polymer-Ph-SO3M is the product of SEBS grafted with benzenesulfonate)

[0023] The cationic reagent M(OH) x It is selected from sodium hydroxide, zinc hydroxide or potassium hydroxide; by controlling the amount of sulfonating agent added, a series of products with a degree of sulfonation of 8% to 25% can be obtained.

[0024] The acetylsulphate is prepared by mixing acetic anhydride and concentrated sulfuric acid at a molar ratio of (1.0 to 1.5):1 at 0 to 5°C.

[0025] The high-transmittance anionic organic dye pigment is an acidic dye containing sulfonic acid or carboxyl groups, with an average particle size of 0.1–2 μm. The mass ratio of the benzenesulfonate-grafted SEBS polymer to the anionic organic dye pigment is (40–400):1.

[0026] Preferably, the high-transmittance anionic organic dye pigment is an acidic dye containing sulfonic acid groups, with an average particle size of 0.1 to 1 μm.

[0027] The high-transmittance filler is magnesium sulfate whiskers or hollow glass microspheres with a whiteness ≥90% and an average particle size of 0.5-5μm.

[0028] Preferably, the high-transmittance filler is magnesium sulfate whiskers with an average particle size of 1–3 μm.

[0029] The antioxidant is one or a mixture of two or more of the following: pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (antioxidant 1010), tris[2,4-di-tert-butylphenyl] phosphite (antioxidant 168), octadecyl thiodipropionate (antioxidant DSTP), and n-octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant 1076).

[0030] Preferably, the antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a 1:1 ratio.

[0031] The other additives are composed of light stabilizers and lubricants in a mass ratio of 1:1; wherein the light stabilizer is one or a combination of hindered amines and ultraviolet absorbers; and the lubricant is one or a combination of esters, stearic acid and stearates.

[0032] Preferably, the other additives are a mixture of hindered amine light stabilizers and stearate lubricants in a 1:1 ratio.

[0033] The specific steps for preparing the above-mentioned novel color-transmitting and light-transmitting polypropylene composite material with high light transmittance, high tinting strength, and high paint adhesion are as follows:

[0034] (1) Prepare a cationic benzenesulfonate-grafted SEBS polymer according to the aforementioned method;

[0035] (2) Weigh the raw materials according to the above weight ratio;

[0036] (3) The weighed polypropylene resin, benzenesulfonate-grafted SEBS polymer, anionic organic dye, antioxidant, and other additives are placed in a high-speed mixer and mixed for 3-5 minutes. The mixture is then fed into a twin-screw extruder through the main feed port at the tail of the screw. The high-transmittance filler is fed into the twin-screw extruder through the side feed port in the middle of the screw. After melt extrusion, the mixture is cooled and granulated. The process is as follows: Zone 1: 190-200℃, Zone 2: 200-210℃, Zone 3: 200-210℃, Zone 4: 205-215℃; Screw speed: 300-500 r / min; Residence time for the entire extrusion process: 1-2 minutes; Pressure: 10-16 MPa; Exhaust vacuum: 5-10 kPa.

[0037] The advantages of this invention are:

[0038] (1) The present invention introduces polar sites on the polymer chain through a precisely controlled sulfonation reaction, which achieves uniform compounding with dye molecules at the molecular level, greatly reduces light scattering caused by dye aggregation, and achieves a light transmittance of up to 74% or more, and significantly improves coloring power.

[0039] (2) The polar sulfonate groups introduced in this invention significantly improve the overall surface energy and polarity of the composite material, thereby greatly improving its interfacial compatibility with polar paint and giving the composite material excellent paint adhesion.

[0040] (3) The immobilization effect based on ionic bonds is much stronger than physical adsorption, which can fundamentally inhibit the migration and precipitation of anionic dyes in the non-polar matrix of polypropylene, and greatly improve migration resistance and color fastness.

[0041] (4) The present invention achieves a perfect balance of light transmittance, color brightness, color fastness and paint adhesion, and its overall performance far exceeds that of the prior art.

[0042] (5) The solvent sulfonation process described above has mild reaction conditions and strong controllability. By adjusting the degree of sulfonation and the type of sulfonate counterion, the properties of the material can be precisely controlled. Attached Figure Description

[0043] Figure 1 This is a process flow diagram for grafting SEBS polymer with benzenesulfonate. Detailed Implementation

[0044] The present invention will be further illustrated below with reference to specific embodiments. It should be emphasized that these embodiments are merely illustrative of the invention and should not be construed as limiting the scope of protection of the invention. Furthermore, it should be understood that after reading the description of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0045] (I) Examples of the preparation of SEBS grafted with benzenesulfonate

[0046] Example 1-1

[0047] Nitrogen gas was introduced into a 1000 mL three-necked flask equipped with a stirrer, condenser, and constant-pressure dropping funnel for protection. 500 mL of dichloromethane and 50 g of SEBS were added, and the mixture was stirred until completely dissolved. The system was cooled to 0–5 °C in an ice-water bath. A solution prepared from 4.5 g of acetylsulphate (prepared by mixing acetic anhydride and concentrated sulfuric acid at a molar ratio of (1.0–1.5):1) and 50 mL of dichloromethane was slowly added dropwise over 30–60 minutes. The ice bath was removed, and the reaction was allowed to proceed at 20–30 °C for 3 hours to obtain a sulfonated SEBS solution. Subsequently, the system was heated to 50 °C, and excess saturated NaOH aqueous solution was slowly added, with vigorous stirring for 2 hours. After the reaction was complete, the reaction solution was poured into 2000 mL of anhydrous ethanol, resulting in the precipitation of a large amount of flocculent precipitate. The precipitate was filtered and washed three times with an ethanol / water mixture (V / V = 1:1). Finally, the sample was vacuum dried at 70°C for 12 hours to obtain sodium benzenesulfonate grafted SEBS (Na-SS-SEBS-L) with a low degree of sulfonation (approximately 8%).

[0048] Examples 1-2

[0049] Nitrogen gas was introduced into a 1000 mL three-necked flask equipped with a stirrer, condenser, and constant-pressure dropping funnel for protection. 500 mL of dichloromethane and 50 g of SEBS were added, and the mixture was stirred until completely dissolved. The system was cooled to 0–5 °C in an ice-water bath. A solution prepared from 9 g of acetylsulphate (prepared by mixing acetic anhydride and concentrated sulfuric acid at a molar ratio of (1.0–1.5):1) and 50 mL of dichloromethane was slowly added dropwise over 30–60 minutes. The ice bath was removed, and the reaction was allowed to proceed at 20–30 °C for 4 hours to obtain a sulfonated SEBS solution. Subsequently, the system was heated to 50 °C, and excess saturated NaOH aqueous solution was slowly added, with vigorous stirring for 2 hours. After the reaction was complete, the reaction solution was poured into 2000 mL of anhydrous ethanol, resulting in the precipitation of a large amount of flocculent precipitate. The precipitate was filtered and washed three times with an ethanol / water mixture (V / V = 1:1). Finally, the sodium benzenesulfonate grafted SEBS (abbreviated as Na-SS-SEBS-M) was obtained by vacuum drying at 70°C for 12 hours. The sulfonation degree was medium (about 15%).

[0050] Examples 1-3

[0051] Nitrogen gas was introduced into a 1000 mL three-necked flask equipped with a stirrer, condenser, and constant-pressure dropping funnel for protection. 500 mL of dichloromethane and 50 g of SEBS were added, and the mixture was stirred until completely dissolved. The system was cooled to 0–5 °C in an ice-water bath. A solution prepared from 13.5 g of acetylsulphate (prepared by mixing acetic anhydride and concentrated sulfuric acid at a molar ratio of (1.0–1.5):1) and 50 mL of dichloromethane was slowly added dropwise over 30–60 minutes. The ice bath was removed, and the reaction was allowed to proceed at 20–30 °C for 5 hours to obtain a sulfonated SEBS solution. Subsequently, the system was heated to 50 °C, and an excess of saturated NaOH aqueous solution was slowly added, with vigorous stirring for 2 hours. After the reaction was complete, the reaction solution was poured into 2000 mL of anhydrous ethanol, resulting in the precipitation of a large amount of flocculent precipitate. The precipitate was filtered and washed three times with an ethanol / water (V / V = 1:1) mixture. Finally, the sample was vacuum dried at 70°C for 12 hours to obtain sodium benzenesulfonate grafted SEBS (abbreviated as Na-SS-SEBS-H) with a medium degree of sulfonation (approximately 25%).

[0052] Examples 1-4

[0053] Nitrogen gas was introduced into a 1000 mL three-necked flask equipped with a stirrer, condenser, and constant-pressure dropping funnel for protection. 500 mL of dichloromethane and 50 g of SEBS were added, and the mixture was stirred until completely dissolved. The system was cooled to 0–5 °C in an ice-water bath. A solution prepared from 9 g of acetylsulphate (prepared by mixing acetic anhydride and concentrated sulfuric acid at a molar ratio of (1.0–1.5):1) and 50 mL of dichloromethane was slowly added dropwise over 30–60 minutes. The ice bath was removed, and the reaction was allowed to proceed at 20–30 °C for 4 hours to obtain a sulfonated SEBS solution. Subsequently, the system was heated to 55 °C, and an excess of saturated Zn(OH)₂ aqueous solution was slowly added, while the mixture was stirred vigorously for 2 hours. After the reaction was complete, the reaction solution was poured into 2000 mL of anhydrous ethanol, resulting in the precipitation of a large amount of flocculent precipitate. The precipitate was filtered and washed three times with an ethanol / water mixture (V / V = 1:1). Finally, the mixture was vacuum dried at 70°C for 12 hours to obtain zinc benzenesulfonate-grafted SEBS (abbreviated as Zn-SS-SEBS-M) with a medium degree of sulfonation (approximately 15%).

[0054] (II) Examples and Comparative Examples of the Preparation of Color-Developing and Transparent Polypropylene Composite Materials

[0055] Example 2-1

[0056] The main components of the polypropylene composite material of this invention include 73.6% polypropylene resin, 15% low-sulfonation sodium benzenesulfonate grafted SEBS (Na-SS-SEBS-L), 10% magnesium sulfate whiskers, 0.1% anionic organic dye, 0.3% antioxidant, and 1% other additives.

[0057] Example 2-2

[0058] The main components of the polypropylene composite material of this invention include 73.6% polypropylene resin, 15% medium-sulfonated sodium benzenesulfonate grafted SEBS (Na-SS-SEBS-M), 10% magnesium sulfate whiskers, 0.1% anionic organic dye, 0.3% antioxidant, and 1% other additives.

[0059] Example 2-3

[0060] The main components of the polypropylene composite material of this invention include 73.6% polypropylene resin, 15% high-sulfonation sodium benzenesulfonate grafted SEBS (Na-SS-SEBS-H), 10% magnesium sulfate whiskers, 0.1% anionic organic dye, 0.3% antioxidant, and 1% other additives.

[0061] Examples 2-4

[0062] The main components of the polypropylene composite material of this invention include 73.6% polypropylene resin, 15% medium-sulfonated zinc benzenesulfonate grafted SEBS (Zn-SS-SEBS-M), 10% magnesium sulfate whiskers, 0.1% anionic organic dye, 0.3% antioxidant, and 1% other additives.

[0063] Examples 2-5

[0064] The main components of the polypropylene composite material of this invention include 73.6% polypropylene resin, 15% medium-sulfonated sodium benzenesulfonate grafted SEBS (Na-SS-SEBS-M), 10% hollow glass microspheres, 0.1% anionic organic dyes, 0.3% antioxidants, and 1% other additives.

[0065] Comparative Example 1

[0066] The main components of the polypropylene composite material of this invention include 73.6% polypropylene resin, 15% conventional SEBS, 10% magnesium sulfate whiskers, 0.1% anionic organic dye, 0.3% antioxidant, and 1% other additives.

[0067] Comparative Example 2

[0068] The main components of the polypropylene composite material of this invention include 73.3% polypropylene resin, 15% conventional SEBS, 10% magnesium sulfate whiskers, 0.4% organic phthalocyanine blue pigment, 0.3% antioxidant, and 1% other additives.

[0069] Comparative Example 3

[0070] The main components of the polypropylene composite material of this invention include 73.3% polypropylene resin, 15% medium-sulfonated sodium benzenesulfonate grafted SEBS (Na-SS-SEBS-M), 10% magnesium sulfate whiskers, 0.4% organic phthalocyanine blue pigment, 0.3% antioxidant, and 1% other additives.

[0071] Comparative Example 4

[0072] The main components of the polypropylene composite material of this invention include 72.7% polypropylene resin, 15% medium-sulfonated sodium benzenesulfonate grafted SEBS (Na-SS-SEBS-M), 10% magnesium sulfate whiskers, 1% inorganic ultramarine pigment, 0.3% antioxidant, and 1% other additives.

[0073] Comparative Example 5

[0074] The main components of the polypropylene composite material of this invention include 73.6% polypropylene resin, 15% maleic anhydride grafted SEBS (MAH-g-SEBS), 10% magnesium sulfate whiskers, 0.1% anionic organic dye, 0.3% antioxidant, and 1% other additives.

[0075] Comparative Example 6

[0076] The main components of the polypropylene composite material of this invention include 72.6% polypropylene resin, 15% conventional SEBS, 10% magnesium sulfate whiskers, 1% sodium dodecylbenzenesulfonate, 0.1% anionic organic dye, 0.3% antioxidant, and 1% other additives.

[0077] The content of each component in Examples 2-1 to 2-5 and Comparative Examples 1 to 6 of the present invention is shown in Table 1.

[0078] Table 1. Content (mass percentage) of each major component in the examples and comparative examples.

[0079]

[0080] The raw materials described in the embodiments and comparative examples in Table 1 above are as follows:

[0081] The polypropylene resin was produced by Shandong Jingbo Polyolefin New Materials Co., Ltd., with the trade name RP340R, and a melt flow rate of 28 g / 10 min at 230℃ and 2.16 kg. SEBS was produced by Kraton Pharmaceuticals, USA, with the trade name G1643 and a styrene content of 20%. MAH-g-SEBS was also produced by Kraton Pharmaceuticals, USA, with the trade name FG1901 and a grafting rate of 1.7%. Sodium dodecylbenzenesulfonate was provided by Wuhan Pushida Biotechnology Co., Ltd., with the trade name LAS-80. Magnesium sulfate whiskers, with the trade name NP-YW2, approximately 1.5 μm in diameter and an aspect ratio of approximately 30:1, were produced by Shanghai Fengzhu Composite New Materials Technology Co., Ltd. The hollow glass microspheres had an average particle size of 20 μm and a bulk density of 0.425 g / cm³. 3 Commercially available; the anionic organic dye is Acid Red G, with an average particle size of 0.5 μm, also commercially available; both organic phthalocyanine blue and inorganic ultramarine pigments are commercially available; antioxidant 1010, chemically named pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and antioxidant 168, chemically named tris(2,4-di-tert-butylphenyl)phosphite, are both manufactured by BASF; among other auxiliaries, the light stabilizer is UV-5229 provided by Xinxiu Chemical, and the lubricant is magnesium stearate from Shanghai Yuanye Biotechnology Co., Ltd.; all chemical reagents involved in the preparation of benzenesulfonate grafted SEBS are commercially available products.

[0082] The specific implementation methods of the above embodiments and comparative examples are as follows:

[0083] (1) Cationic benzenesulfonate-grafted SEBS polymers were prepared according to the specific embodiments in Examples 1-1 to 1-4;

[0084] (2) Weigh the raw materials according to the above weight ratio;

[0085] (3) The weighed polypropylene resin, benzenesulfonate-grafted SEBS polymer or conventional SEBS or maleic anhydride-grafted SEBS, anionic organic dye or organic phthalocyanine blue pigment or inorganic ultramarine pigment, sodium dodecylbenzenesulfonate, antioxidant and other additives are placed in a high-speed mixer and mixed for 3-5 minutes. The mixture is then fed into the twin-screw extruder through the main feed port at the tail of the screw. Magnesium sulfate whiskers or hollow glass microspheres are fed into the twin-screw extruder through the side feed port in the middle of the screw. After melt extrusion, the mixture is cooled and granulated. The process is as follows: Zone 1: 190-200℃, Zone 2: 200-210℃, Zone 3: 200-210℃, Zone 4: 205-215℃; Screw speed: 300-500 r / min; Residence time for the entire extrusion process: 1-2 minutes; Pressure: 10-16 MPa; Exhaust vacuum: 5-10 kPa.

[0086] The composite material particles prepared according to the above embodiments and comparative examples were dried in a forced-air oven at 80-100°C for 2 hours. The dried particles were then injection molded on an injection molding machine, and then performance tests were performed.

[0087] Light transmittance test: According to GB / T 2410-2008 standard, the light transmittance was measured using a light transmittance haze tester at an environment of 23±2℃. The sample size was 50*50*2.5mm. Two points were taken from the front and two points from the back of each sample, and the average value was taken.

[0088] Tinting strength and color vibrancy evaluation: The color vibrancy of the sample was observed in a standard light source box using a D65 light source and a fixed observation angle. The color vibrancy and saturation were graded as follows: Grade 1 (very vibrant and saturated), Grade 2 (vibrant but not saturated), Grade 3 (moderately vibrant and saturated), and Grade 4 (dull).

[0089] Pigment dispersion performance evaluation: A 150*100*1mm injection molded sample was observed and counted on the sample surface using a D65 light source and a fixed viewing angle in a standard light source box.

[0090] Migration resistance test: Injection mold a 150*100*3.2mm sample, and bring the sample into close contact with a white ABS sample at 80℃ and 0.5MPa pressure for 168 hours, and observe whether the ABS sample is stained.

[0091] Color fastness test: According to GB / T 16422 standard, the sample was placed in a xenon lamp test chamber for 1000 hours, and the color difference L / a / b values ​​of the sample before and after the experiment were tested according to the formula. Calculate the ΔE value; the smaller the value, the better the color fastness.

[0092] Surface tension test: The surface dyne value was used for characterization. A 150*100*3.2mm injection molded sample was tested for its surface dyne value using a dyne pen. The higher the dyne value, the greater the surface tension of the sample.

[0093] Paint adhesion performance test: Evaluation was conducted using a high-pressure water jet method. A 150*100*3.2mm injection-molded sample was painted using the same process. After 7 days of aging at room temperature, a high-pressure water jet test was performed. The specific experimental method was as follows: On the painted sample, X lines were drawn down to the bottom layer of the coating using a scriber. Each line was 100mm long. The high-pressure nozzle was aimed at each edge of the X lines and sprayed, with the nozzle distance from the line being 13cm, the spray angle at 90°, the water temperature at 60℃, the flow rate at 11.5L / min, and the spraying time at 60s. The degree of coating peeling after spraying was graded as follows: Grade 1 (no coating peeling), Grade 2 (slight coating peeling at the X lines), Grade 3 (significant coating peeling at the X lines), Grade 4 (large-area coating peeling). The lower the grade, the better the adhesion between the substrate and the paint.

[0094] The performance test results of the color-developing and light-transmitting polypropylene composite materials of Examples 2-1 to 2-5 and Comparative Examples 1 to 6 of the present invention are shown in Table 2.

[0095] Table 2. Material performance test data for the examples and comparative examples.

[0096]

[0097] The performance comparisons of the examples and comparative examples show that the simultaneous introduction of benzenesulfonate-grafted SEBS and anionic organic dyes not only imparts high light transmittance to the composite material but also significantly improves the coloring effect, pigment migration resistance, and paint adhesion of the composite system. Especially when the sulfonation degree of benzenesulfonate-grafted SEBS is 15%, the composite material achieves optimal or excellent levels in all key indicators, including light transmittance, color brightness, color fastness, surface tension, and paint adhesion, fully demonstrating the excellent and balanced comprehensive performance achievable by the technical solution of this invention. The comparisons of Examples 2-1 to 2-3 show that there is an optimal sulfonation degree for benzenesulfonate-grafted SEBS (10%–20%). Too low a degree results in insufficient anchoring points, leading to performance limitations, while too high a degree slightly sacrifices light transmittance.

[0098] The comparison between Examples 2-2 and Comparative Examples 1, 5, and 6 shows that when using conventional SEBS with anionic organic dyes, the lack of cationic polymers to fix the dye molecules leads to severe dye migration and poor paint adhesion due to the reduced surface tension caused by the dyes. Even the addition of maleic anhydride-grafted SEBS with polar groups or small-molecule surfactants containing benzenesulfonates has little effect, indicating the necessity of chemically grafting cationic functional groups onto the polymer backbone in this invention. The comparison between Examples 2-2 and Comparative Examples 3 and 4 shows that the addition of benzenesulfonate-grafted SEBS improves the surface tension and paint adhesion of the composite material to some extent. However, since conventional organic and inorganic pigments lack cationic components, they cannot form chemical bonds with benzenesulfonate-grafted SEBS, resulting in poor pigment dispersion and numerous pigment accumulation points in the samples, affecting the appearance of the products. Furthermore, conventional organic and inorganic pigments have a certain light-blocking effect, leading to a significant reduction in the transmittance of the composite material, especially for inorganic pigments, where the transmittance is reduced by more than 30%, failing to meet the requirements for high-transmittance products.

[0099] In addition, Examples 2-4 and 2-5 achieved performance comparable to that of the core Example 2-2, indicating that the technical solution of the present invention has good adaptability and a wide process window for different benzenesulfonate-grafted SEBS and transparent filler systems, further enhancing its industrial application value.

[0100] Through the above systematic technical demonstration, the technical effect of the present invention has been fully verified and the optimal technical solution in this embodiment of the invention has been determined to be the technical solution of medium sulfonation degree benzenesulfonate grafted SEBS and anionic organic dye compounded in Examples 2-2, 2-4 and 2-5, and the optimal sulfonation degree window of medium sulfonation degree benzenesulfonate grafted SEBS is 10% to 20%.

Claims

1. A novel color-transmitting and light-transmitting polypropylene composite material with high light transmittance, high tinting strength, and high paint adhesion, characterized in that: Formulated from the following ingredients by weight percentage:

2. The novel color-transmitting, high-tinting-strength, and high-paint adhesion polypropylene composite material according to claim 1, characterized in that: The polypropylene resin is atactic polypropylene resin, with a light transmittance of ≥65% when the sample thickness is 3mm, and a melt flow rate of 1~30g / 10min under conditions of 230℃ and 2.16kg load.

3. The novel color-transmitting and light-transmitting polypropylene composite material with high light transmittance, high tinting strength, and high paint adhesion according to claim 1, characterized in that: The process for grafting SEBS polymers with benzenesulfonate is as follows: using acetylsulphate as a controllable sulfonating agent, selective electrophilic substitution of polystyrene blocks in the SEBS molecular chain is performed by solution method, followed by alkaline neutralization and other techniques to construct a polymer with stable polar sulfonate side chains.

4. The novel color-transmitting and light-transmitting polypropylene composite material with high light transmittance, high tinting strength, and high paint adhesion as described in claim 3, characterized in that: The specific preparation steps of the benzenesulfonate-grafted SEBS polymer are as follows: (1) Sulfonation reaction: Under an inert atmosphere and with continuous stirring, SEBS is dissolved in an aprotic organic solvent to form a solution with a mass-volume concentration of 5% to 15%, and the system temperature is controlled at 0 to 5°C; then, the sulfonating reagent acetylsulphate is slowly added dropwise, and the addition time is controlled at 30 to 60 minutes. The molar ratio of acetylsulphate to styrene structural units in SEBS is (0.1 to 0.5:1); after the addition is complete, the reaction is carried out at 20 to 40°C for 1 to 4 hours to obtain the sulfonated intermediate; The main chemical process of the sulfonation reaction is represented by the following general formula: Polymer -Ph-H + CH3C(O)OSO3H → Polymer -Ph-SO3H + CH3COOH (Where, Ph represents a benzene ring) (2) Salt formation reaction: Add a cationic reagent to the reaction system obtained in step (1) and carry out a neutralization reaction at 30-60°C for 1-3 hours to convert the sulfonic acid group into the sulfonate group; after the reaction is completed, the final product benzenesulfonate grafted SEBS polymer is obtained by non-solvent precipitation, separation, washing and vacuum drying. The main chemical process of the salt-forming reaction is represented by the following general formula: Polymer -Ph-SO3H+M(OH) x →polymer-Ph-SO3M+H2O (Among them, polymer-Ph-SO3M is the product of SEBS grafted with benzenesulfonate) The cationic reagent M(OH) x It is selected from sodium hydroxide, zinc hydroxide or potassium hydroxide; by controlling the amount of sulfonating agent added, a series of products with a degree of sulfonation of 8% to 25% can be obtained.

5. The novel color-transmitting and light-transmitting polypropylene composite material with high light transmittance, high tinting strength, and high paint adhesion according to claim 3, characterized in that: The acetylsulphate is prepared by mixing acetic anhydride and concentrated sulfuric acid at a molar ratio of (1.0 to 1.5):1 at 0 to 5°C.

6. The novel color-transmitting and light-transmitting polypropylene composite material with high light transmittance, high tinting strength, and high paint adhesion according to claim 1, characterized in that: The anionic organic dye is an acidic dye containing sulfonic acid or carboxyl groups, with an average particle size of 0.1–2 μm. The mass ratio of the benzenesulfonate-grafted SEBS polymer to the anionic organic dye is (40–400):

1.

7. The novel color-transmitting and light-transmitting polypropylene composite material with high light transmittance, high tinting strength, and high paint adhesion according to claim 1, characterized in that: The high-transmittance filler is magnesium sulfate whiskers or hollow glass microspheres with a whiteness ≥90% and an average particle size of 0.5-5μm.

8. The novel color-transmitting and light-transmitting polypropylene composite material with high light transmittance, high tinting strength, and high paint adhesion according to claim 1, characterized in that: The antioxidant is one or a mixture of two or more of the following: pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (antioxidant 1010), tris[2,4-di-tert-butylphenyl] phosphite (antioxidant 168), octadecyl thiodipropionate (antioxidant DSTP), and n-octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant 1076).

9. The novel color-transmitting and light-transmitting polypropylene composite material with high light transmittance, high tinting strength, and high paint adhesion according to claim 1, characterized in that: The other additives are composed of light stabilizers and lubricants in a mass ratio of 1:1; wherein the light stabilizer is one or a combination of hindered amines and ultraviolet absorbers; and the lubricant is one or a combination of esters, stearic acid and stearates.

10. A novel color-transmitting and light-transmitting polypropylene composite material with high light transmittance, high tinting strength, and high paint adhesion as described in claims 1-9, characterized in that: The specific steps are as follows: (1) The method according to claim 4 is used to prepare a cationic benzenesulfonate-grafted SEBS polymer; (2) Weigh the raw materials according to the above weight ratio; (3) The weighed polypropylene resin, benzenesulfonate-grafted SEBS polymer, anionic organic dye, antioxidant, and other additives are placed in a high-speed mixer and mixed for 3-5 minutes. The mixture is then fed into a twin-screw extruder through the main feed port at the tail of the screw. The high-transmittance filler is fed into the twin-screw extruder through the side feed port in the middle of the screw. After melt extrusion, the mixture is cooled and granulated. The process is as follows: Zone 1: 190-200℃, Zone 2: 200-210℃, Zone 3: 200-210℃, Zone 4: 205-215℃; Screw speed: 300-500 r / min; Residence time for the entire extrusion process: 1-2 minutes; Pressure: 10-16 MPa; Exhaust vacuum: 5-10 kPa.

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