A low-odor, high-performance, thin-walled polypropylene composite material and a preparation method thereof

Abstract

The application discloses a kind of low odor, high performance, thin-walled polypropylene composite material and preparation method thereof, it includes the following weight parts of raw materials: high flow polypropylene: 40.5-68.5;Low shrinkage polypropylene: 0-20;Talc: 10-20;Elastomer: 8-16;Odor extractant: 1-5;Rheological agent: 0-1;Lubricant: 0-1;Antioxidant: 0-1;Other additives: 0-3;The preparation process of low odor, high performance, thin-walled polypropylene composite material proposed in the application is relatively simple, and the production cost is relatively low, and the thin-walled polypropylene composite material with more excellent comprehensive performance can be prepared.

Description

Technical Field

[0001] This invention belongs to the field of polymer modification and processing technology, and relates to a low-odor, high-performance, thin-walled polypropylene composite material and its preparation method. Background Technology

[0002] In new energy vehicles, lightweight vehicle technology is crucial for improving energy efficiency and driving range. Among them, the thin-wall design of polypropylene plastic parts, which are used in the largest quantity in automobiles, is one of the most important automotive lightweighting technologies and is currently widely used in automotive interior and exterior parts, such as bumpers, dashboards, door panels, pillars, and other interior and exterior parts.

[0003] However, thin-walled polypropylene materials are prone to low dimensional accuracy during injection molding. This is mainly because after demolding, the release of internal stress causes a certain degree of shrinkage, which may lead to large deviations in assembly gaps between parts. Especially for some parts with complex structures, large dimensions, and long processes, in order to ensure that the surface of the parts is free from shrinkage marks, weld lines, deformation, and other problems, higher injection temperatures and holding pressures are often used in the injection molding process. However, higher injection temperatures and longer holding times cause the modified polypropylene melt to remain in the mold for too long, resulting in a certain degree of oxidation and decomposition, producing some small molecular substances. This affects the odor emission performance of thin-walled parts, which is detrimental to the interior environment of the vehicle and can seriously affect the health of the driver and passengers.

[0004] In order to cope with the rapid growth trend of new energy vehicles, increase the application of thin-walled polypropylene materials in vehicle lightweighting technology, and meet customers' quality requirements for automotive interior environment, it is of great significance to develop a low-odor, high-performance, thin-walled polypropylene composite material. Summary of the Invention

[0005] To further increase the application rate of thin-walled polypropylene materials in automotive interior and exterior parts and address the shortcomings of existing technologies, this invention aims to provide a low-odor, high-performance, thin-walled polypropylene composite material and its preparation method. This method primarily involves introducing a portion of low-shrinkage copolymer polypropylene into the conventional polypropylene material formulation to replace high-flow copolymer polypropylene, ensuring the composite material system maintains good dimensional accuracy during molding and reducing part dimensional deviations. Simultaneously, an odor extractant is introduced into the formulation system. This is a liquid additive, using deionized water as a solution, and compounded with the surfactant dodecyl dimethylamine acetone and ethanol in a 1:1 ratio. During extrusion, the odor extractant utilizes the surfactant itself to form numerous microbubbles, increasing the contact area with small-molecule volatile substances generated in the melt, effectively removing these substances and improving the odor extraction process. The odor emission performance of thin-walled polypropylene composites is improved. Simultaneously, a new rheology modifier is introduced into the formulation. Its core component is modified using traditional free radicals as a base material, which can promote the dispersion of POE elastomer in the polypropylene composite formulation system, improve the compatibility between polypropylene and the POE phase, and effectively enhance the flowability of the modified polypropylene composite system while ensuring that the notched impact toughness of the composite system is not lost. This compensates for the flowability loss caused by the introduction of low-shrinkage copolymer polypropylene. The rheology modifier can work synergistically with low-shrinkage polypropylene, thereby ensuring that the prepared thin-walled polypropylene composite has excellent comprehensive performance, and the parts have a good surface finish without defects.

[0006] To achieve the above objectives, the present invention specifically adopts the following technical solution:

[0007] A low-odor, high-performance, thin-walled polypropylene composite material comprising the following raw materials in parts by weight:

[0008] High-flow polypropylene: 40.5-68.5;

[0009] Low-shrinkage polypropylene: 0-20;

[0010] Talc: 10-20;

[0011] Elastomer: 8-16;

[0012] Odor extractant: 1-5;

[0013] Rheology modifier: 0-1;

[0014] Lubricant: 0-1;

[0015] Antioxidant: 0-1;

[0016] Other additives: 0-3.

[0017] The high-flow polypropylene is a copolymer polypropylene with a melt index (230℃, 2.16KG) of about 60g-100g / 10min.

[0018] The low-shrinkage polypropylene is a copolymer polypropylene with a melt index (230℃, 2.16KG) of approximately 20g-50g / 10min.

[0019] The talc powder mentioned is a 10,000-mesh talc powder material.

[0020] The elastomer is an ethylene-octene copolymer with a density of 0.86-0.90 g / cm³. 3 The melt flow index is 0.5-6 g / 10 min.

[0021] The odor extractant is a liquid additive, using deionized water as a solution, and is formulated with the surfactant dodecyl dimethylamine acetyl alcohol and ethanol in a 1:1 ratio.

[0022] The rheology modifier is an additive that can improve the flowability of modified polypropylene composite material systems;

[0023] The lubricant is a composite lubricant, which is a mixture of ethylene bis-stearamide and magnesium stearate in a 1:1 ratio.

[0024] The antioxidants mentioned are those deemed necessary by those skilled in the art, and are mainly composed of one 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 octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (antioxidant 1076).

[0025] The other additives mentioned are one or more of various color components, light stabilizers, processing aids, etc., which are considered necessary by those skilled in the art.

[0026] The preparation method of the above-mentioned low-odor, high-performance, thin-walled polypropylene composite material comprises the following steps:

[0027] A. Preparation of odor extractant:

[0028] Odor extractant, using deionized water as solution, is prepared by compounding dodecyl dimethylamine betaine and ethanol in a 1:1 ratio, wherein the total mass percentage of dodecyl dimethylamine betaine and ethanol in the aqueous solution is 10%. The mixture is stirred until homogeneous solution is obtained and set aside for later use.

[0029] B. Low-odor, high-performance, thin-walled polypropylene composites and their preparation:

[0030] (1) Weigh and prepare the above components according to the mass ratio;

[0031] (2) Place the high-flow polypropylene, low-shrinkage polypropylene, talc, elastomer, rheology modifier, odor extractant, lubricant, antioxidant, and other additives into a high-speed mixer and mix at high speed for 5-10 minutes; reserve half of the odor extractant for later use.

[0032] (3) The above-mentioned uniformly mixed raw materials are added to the twin-screw extruder through the main feed port. The remaining half of the odor extractant is added to the twin-screw extruder through the side feed port in the middle of the twin-screw extruder. The side feed port is preferably located between the exhaust port and the vacuum port of the extruder, in the sixth section of the extruder barrel. The injection speed of the liquid extractant should be well matched with the feeding speed of the extruder. If the injection is too fast, the melt will cool down too quickly, affecting the speed of the main machine. If the injection is too slow, it will affect the removal effect of small molecules. Then, the mixed components are melt extruded, stretched, cooled, and granulated. After drying, a low-odor, high-performance, thin-walled polypropylene composite material is prepared. The processing temperatures of each zone of the twin-screw extruder are as follows: Zone 1: 185-200℃, Zone 2: 190-205℃, Zone 3: 210-215℃, Zone 4: 205-210℃, and the die head: 190-200℃. The entire extrusion process takes about 2 minutes, with a pressure of 12-18 MPa, a main screw speed of 500-800 r / min, and a water tank temperature of 30-60℃. A double vacuum system is added to both sides of the twin-screw extruder, with a vacuum degree of -0.07 MPa to -0.08 MPa. The drying process adopts a new drying process: storage in tank A, drying in tank B, and cooling in tank C. The drying process in tank B is 130℃ for 6 hours.

[0033] The advantages of this invention are:

[0034] (1) In the formulation design of thin-walled polypropylene composite materials, the present invention introduces some low-shrinkage copolymer polypropylene to replace high-flow copolymer polypropylene, so as to ensure that the composite material system maintains good dimensional accuracy during the molding process, reduce part dimensional deviation, and ensure the dimensional stability of the parts.

[0035] (2) The odor extractant selected in this invention includes the surfactant dodecyl dimethylamine acetone, which is stable in acid and alkali systems and has strong cleaning ability. During the extrusion process, it forms a large number of microbubbles, which can increase the contact area between itself and the small molecule volatile substances generated in the polypropylene melt. This can effectively remove the small molecule substances generated during the extrusion process and improve the odor emission performance of the thin-walled polypropylene composite material.

[0036] (3) The rheology modifier selected in this invention is modified with traditional free radicals as the base material. It can promote the dispersion of POE elastomer in the polypropylene composite material formulation system, improve the compatibility between polypropylene and POE phase, and effectively improve the fluidity of the modified polypropylene composite material system while ensuring that the notched impact toughness of the composite material system is not lost. It can make up for the fluidity loss caused by the introduction of low shrinkage copolymer polypropylene. The rheology modifier can play a synergistic role with low shrinkage polypropylene, thereby ensuring that the prepared thin-walled polypropylene composite material has excellent comprehensive performance.

[0037] (4) The preparation process of the low-odor, high-performance, thin-walled polypropylene composite material proposed in this invention is relatively simple and has a low production cost. It can produce thin-walled polypropylene composite materials with better comprehensive performance. Detailed Implementation

[0038] The present invention will now be described in detail with reference to specific examples. Unless otherwise specified, all components in the examples are parts by weight.

[0039] The content of each component in the embodiments and comparative examples of the present invention is shown in Table 1.

[0040] Table 1. Content (mass percentage) of each major component in the examples and comparative examples.

[0041]

[0042] The high-flow polypropylene described in the examples and comparative examples in Table 1 above is a 1:1 blend of BX3900 and BX3920. BX3900 is manufactured by SK Corporation of Korea, with a melt flow rate of 60 g / 10 min, while BX3920, also manufactured by SK Corporation of Korea, has a melt flow rate of 100 g / 10 min. The low-shrinkage polypropylene is a 1:1 blend of EP246P and PP7585. EP246P is manufactured by Basel Chemical Company, with a melt flow rate of 20 g / 10 min, while PP7585 is manufactured by ExxonMobil, with a melt flow rate of 50 g / 10 min. The talc powder is approximately 10,000 mesh and sourced from Shanghai Yuanjiang Chemical Co., Ltd. The elastomer is a thermoplastic POE elastomer manufactured by Dow Chemical Company, grade 7467. The deionized water and ethanol in the odor extractant are commercially available; the surfactant dodecyl dimethylamine hydantoin is from Shanghai Shengwei Chemical Raw Materials Co., Ltd. The odor adsorbent is commercially available; the rheology modifier is from Chongqing Baozhuan New Materials Technology Co., Ltd. The ethylene bis-stearamide in the lubricant is from Sigma-Aldrich (Shanghai) Trading Co., Ltd.; the magnesium stearate is from Shanghai Yuanye Biotechnology Co., Ltd. The antioxidant is a compound antioxidant of 1010 (pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) / tris[2,4-di-tert-butylphenyl]phosphite (antioxidant 168) / DSTP (octadecyl thiodipropionate) in a mass ratio of 1:2:1. Other additives mainly refer to color components, light stabilizers, etc.

[0043] The specific implementation methods of the above embodiments and comparative examples are as follows:

[0044] A. Preparation of odor extractant:

[0045] Odor extractant, using deionized water as solution, is prepared by compounding dodecyl dimethylamine betaine and ethanol in a 1:1 ratio, wherein the total mass percentage of dodecyl dimethylamine betaine and ethanol in the aqueous solution is 10%. The mixture is stirred until homogeneous solution is obtained and set aside for later use.

[0046] B. Low-odor, high-performance, thin-walled polypropylene composites and their preparation:

[0047] (1) Weigh and prepare the above components according to the mass ratio;

[0048] (2) Place the high-flow polypropylene, low-shrinkage polypropylene, talc, elastomer, rheology modifier, odor extractant, lubricant, antioxidant, and other additives into a high-speed mixer and mix at high speed for 5-10 minutes; reserve half of the odor extractant for later use.

[0049] (3) The above-mentioned uniformly mixed raw materials are added to the twin-screw extruder through the main feed port. The remaining half of the odor extractant is added to the twin-screw extruder through the side feed port in the middle of the twin-screw extruder. The side feed port is preferably located between the exhaust port and the vacuum port of the extruder, in the sixth section of the extruder barrel. The injection speed of the liquid extractant should be well matched with the feeding speed of the extruder. If the injection is too fast, the melt will cool down too quickly, affecting the speed of the main machine. If the injection is too slow, it will affect the removal effect of small molecules. Then, the mixed components are melt extruded, stretched, cooled, and granulated. After drying, a low-odor, high-performance, thin-walled polypropylene composite material is prepared. The processing temperatures of each zone of the twin-screw extruder are as follows: Zone 1: 185-200℃, Zone 2: 190-205℃, Zone 3: 210-215℃, Zone 4: 205-210℃, and the die head: 190-200℃. The entire extrusion process takes about 2 minutes, with a pressure of 12-18 MPa, a main screw speed of 500-800 r / min, and a water tank temperature of 30-60℃. A double vacuum system is added to both sides of the twin-screw extruder, with a vacuum degree of -0.07 MPa to -0.08 MPa. The drying process adopts a new drying process: storage in tank A, drying in tank B, and cooling in tank C. The drying process in tank B is 130℃ for 6 hours.

[0050] C. Dry the composite material particles prepared as described above in a forced-air oven at 80-100℃ for 2 hours, then perform injection molding on an injection molding machine, and then conduct performance tests.

[0051] D. Basic Mechanical Property Tests: Density was tested according to ISO 1183-1 standard; melt flow index was tested according to ISO 1133-1 standard at a test temperature of 230℃ and a load of 2.16kg; tensile strength was tested according to ISO 527-2 standard with a specimen size of 170*10*4mm and a tensile speed of 50mm / min; flexural modulus was tested according to ISO 178 standard with a specimen size of 80*10*4mm, a span of 64mm, and a bending speed of 2mm / min; notched impact strength of simply supported beams was tested according to ISO 179-1 standard with a specimen size of 80*10*4mm and a notch depth of one-fifth of the specimen width. Shrinkage was tested according to ISO 294 method. Odor testing of parts was performed according to PV 3900 method, taking 50g samples from parts beyond the 30-mold mark, placing them in a 1L odor bottle, 180℃ for 2 hours, and then evaluating at 60℃. Total carbon testing of parts was performed according to PV 3341 method. The overall appearance effect of the parts is evaluated as follows: The material is injection molded into a 200*200*2.5mm hollow template under a specific injection molding process. The template is evaluated by visual inspection and divided into 3 levels according to the presence of shrinkage marks, weld lines, deformation, etc. on the surface. The lower the level, the fewer the appearance defects and the better the appearance effect.

[0052] Table 2. Material performance test data for the examples and comparative examples.

[0053]

[0054] The data results from the examples and comparative examples in the table above show that, through reasonable formulation design, the examples and comparative examples prepared modified polypropylene composite materials with high fluidity and a high balance of rigidity and toughness in different filling systems. Among them, Example 7 prepared a modified polypropylene composite material with 20 parts of filler, which has the best balance of rigidity and toughness, and also has low odor and low shrinkage, which can meet the application requirements of most thin-walled parts for interior and exterior trim. From Examples 1-7 and Comparative Example 1, it can be found that after adding the odor extractant to the formulation, the odor emission and total carbon of the thin-walled polypropylene material continue to decrease with the increase of the amount added. When the weight of the odor extractant is 4 parts, the odor and total carbon can reach the optimal state (Example 7). Further comparison between Example 7 and Comparative Example 4 shows that the polypropylene composite material prepared using commercially available odor adsorbent has a slightly worse odor, but the total carbon performance of Comparative Example 4 is very poor. At the same time, the comprehensive mechanical properties of Comparative Example 4 are also lower than those of Example 7, because the odor extractant is a liquid additive and has almost no effect on the material properties. A further comparison of Examples 1-3 and 4-6, and Example 7 and Comparative Example 1, reveals that under the same filling system, the flowability of the composite material is significantly improved after adding a small amount of rheology modifier, and its impact toughness is not lost due to the improvement in flowability. This shows that rheology modifier is very helpful in dispersing elastomers in the composite material system and improving the compatibility between polypropylene and elastomers. At the same time, a comparison between Example 7 and Comparative Example 1 shows that the flowability of the composite material system is greatly improved after adding rheology modifier, and the prepared sample has an excellent surface appearance without defects such as shrinkage marks, weld lines, or deformation. A comparison of Example 7 and Comparative Examples 2 and 3 reveals that the introduction of low-shrinkage polypropylene significantly improves the shrinkage rate of the composite material system. With increasing proportions of low-shrinkage polypropylene, the shrinkage rate of the 20-part filled polypropylene composite material system can be reduced to 0.64%. This effectively addresses the problem of large assembly gap deviations caused by the increased shrinkage of thin-walled materials in parts applications. Further evaluation of the sample appearance shows that Example 7 performs best. This is because Comparative Examples 2 and 3, due to the addition of less low-shrinkage polypropylene, have a larger overall shrinkage, resulting in a certain degree of shrinkage and shrinkage marks on the sample surface.

[0055] In summary, this invention further optimizes the formulation design of thin-walled polypropylene composite materials by introducing components such as low-shrinkage polypropylene, odor extractant, and rheology modifier, thereby preparing a low-odor, high-performance, thin-walled polypropylene composite material.

Claims

1. A low-odor, high-performance, thin-walled polypropylene composite material, characterized in that, It comprises the following raw materials in parts by weight: high-flow polypropylene: 40.5-68.5; low-shrinkage polypropylene: 10-20; talc: 10-20; elastomer: 8-16; odor extractant: 1-5; rheology modifier: 0.1-1; Lubricant: 0-1; Antioxidant: 0-1; Other additives: 0-3; The high-flow polypropylene is copolymer polypropylene, with a melt index of 60g-100g / 10min under test conditions of 230℃ and 2.16KG; The low-shrinkage polypropylene is copolymer polypropylene, with a melt index of 20g-50g / 10min under test conditions of 230℃ and 2.16KG; The odor extractant is a liquid additive, using deionized water as solvent, and is formulated with surfactant dodecyl dimethylamine hydantoin and ethanol in a 1:1 ratio; The rheology modifier is an additive that can improve the flowability of modified polypropylene composite material systems, from Chongqing Baozhuan New Material Technology Co., Ltd.

2. The low-odor, high-performance, thin-walled polypropylene composite material according to claim 1, characterized in that: The talc powder mentioned is 10,000 mesh talc powder.

3. The low-odor, high-performance, thin-walled polypropylene composite material according to claim 1, characterized in that: The elastomer is an ethylene-octene copolymer with a density of 0.86-0.90 g / cm³. 3 The melt flow index is 0.5-6 g / 10 min.

4. The low-odor, high-performance, thin-walled polypropylene composite material according to claim 1, characterized in that: The lubricant is a composite lubricant, which is a mixture of ethylene bis-stearamide and magnesium stearate in a 1:1 ratio.

5. The low-odor, high-performance, thin-walled polypropylene composite material according to claim 1, characterized in that: The antioxidant is composed of one or more of the following: pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], tris[2,4-di-tert-butylphenyl]phosphite, octadecyl thiodipropionate, and octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

6. The low-odor, high-performance, thin-walled polypropylene composite material according to claim 1, characterized in that: The other additives mentioned are one or more of various color components, light stabilizers, and processing aids.

7. The method for preparing the low-odor, high-performance, thin-walled polypropylene composite material according to any one of claims 1-6, characterized in that, The steps are as follows: A. Preparation of odor extractant: Odor extractant, using deionized water as solvent, is prepared by compounding dodecyl dimethylamine betaine and ethanol in a 1:1 ratio, wherein the total mass percentage of dodecyl dimethylamine betaine and ethanol in the aqueous solution is 10%. The mixture is stirred until homogeneous and ready for use. B. Preparation of low-odor, high-performance, thin-walled polypropylene composite materials: (1) Weigh and prepare each component according to the mass ratio; (2) Place the high-flow polypropylene, low-shrinkage polypropylene, talc, elastomer, rheology modifier, odor extractant, lubricant, antioxidant, and other additives into a high-speed mixer and mix at high speed for 5-10 minutes; reserve half of the odor extractant for later use. (3) The uniformly mixed raw materials are added to the twin-screw extruder through the main feed port. The remaining half of the odor extractant is added to the twin-screw extruder through the side feed port in the middle of the extruder. The side feed port is located between the exhaust port and the vacuum port of the extruder, in the sixth section of the extruder barrel. The injection speed of the liquid extractant should be well matched with the feeding speed of the extruder. If the injection is too fast, the melt will cool down too quickly, affecting the speed of the main extruder. If the injection is too slow, it will affect the removal effect of small molecules. Then, the mixed components are melt-extruded, stretched, cooled, and granulated. After drying, a low-odor, high-performance, thin-walled polypropylene composite material is prepared. The processing temperatures of each zone of the twin-screw extruder are as follows: Zone 1: 185-200℃, Zone 2: 190-205℃, Zone 3: 210-215℃, Zone 4: 205-210℃, and the die head: 190-200℃. The entire extrusion process takes 2 minutes, with a pressure of 12-18 MPa, a main screw speed of 500-800 r / min, and a water tank temperature of 30-60℃. Dual vacuum systems are added to both sides of the twin-screw extruder, with a vacuum degree of -0.07MPa to -0.08MPa. A new drying process is adopted for the material drying: storage in tank A, drying in tank B, and cooling in tank C. The drying process in tank B is 130℃ for 6 hours.

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