Shock-absorbing, noise-reducing, low-emission long glass fiber reinforced polypropylene composite material with good surface appearance for automobile interior and preparation method thereof

Abstract

The present invention relates to the technical field of polypropylene composite materials, and specifically discloses a high-performance, shock-absorbing, noise-reducing, and low-emission long glass fiber-reinforced polypropylene composite material with a good appearance for automotive interiors, and a preparation method thereof. The composite material comprises 5-50 wt% continuous glass fiber; 1-25 wt% high-melt-strength elastomer; 1-15 wt% ethylene-acrylate copolymer; 0.1-2 wt% rare earth stearate; 0.5-2 wt% color powder; 0.1-1 wt% other additives; and polypropylene as the remaining components. The present invention significantly increases the mutual friction between the glass fiber and the polymer molecular chains, as well as between the PP and elastomer molecular chains, by blending and modifying the high-melt-strength elastomer and the ethylene-acrylate copolymer in the modified formula, thereby improving the loss modulus of the polypropylene composite material and achieving superior shock-absorbing, noise-reducing, and emission characteristics.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and in particular to a long glass fiber reinforced polypropylene composite material for automobile interior decoration with good surface appearance, vibration reduction, noise reduction and low emission, and a preparation method thereof. Background Art

[0002] Long glass fiber reinforced polypropylene (LGF-PP) is a high-strength, lightweight composite material. Compared to metal and traditional thermoset composites that replace steel with plastic, LGF-PP can reduce the weight of the same component by 20-50%. It can also be molded into complex shapes, reduce energy consumption, and simplify assembly processes, offering significant competitive advantages in the automotive lightweighting sector.

[0003] Under the influence of external conditions such as heat and light, LGF-PP materials react with oxygen to produce free radicals, which break the PP molecular chains and reduce the relative molecular weight, resulting in poor emission characteristics, which affects the application of LGF-PP materials in automotive interiors. To ensure good impregnation of long glass fibers with the resin, lubricants and compatibilizers are added, and a specially structured impregnation mold cavity is used to ensure good dispersion of the glass fibers in the resin, reducing the appearance of floating fibers during the injection molding process.

[0004] CN201210288635.7 and CN201210288577.8 use maleic anhydride-grafted polypropylene (PP-g-MAH) as a compatibilizer to promote the full impregnation of glass fiber in the melt; CN200610033859.8 focuses on the PP raw material, using ultra-high melt index unsaturated carboxylic acids or their anhydrides to modify PP to promote interfacial bonding with glass fiber. Anhydride-grafted PP can improve the interfacial bonding between PP and glass fiber, but due to factors such as the preparation process, the emission characteristics of anhydride-grafted PP are relatively poor, hindering the application of LGF-PP materials in interior decoration. Furthermore, PP-LGF materials used in frequently opened and closed parts such as tailgates must not only meet high mechanical performance requirements but also meet the functional requirements of vibration and noise reduction. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a long glass fiber reinforced polypropylene composite material that can be used in the field of automobile interior and has good surface appearance and is shock-absorbing, noise-reducing and low-emission.

[0006] The object of the present invention is achieved through the following technical solutions:

[0007] A long glass fiber reinforced polypropylene composite material with good surface appearance and low emission and vibration reduction for automotive interiors, comprising the following raw materials in the following weight percentages:

[0008] Continuous glass fiber: 5-50wt%;

[0009] High melt strength elastomer 1-25wt%;

[0010] Ethylene-acrylate copolymer: 1-15wt%;

[0011] Rare earth stearate: 0.1-2wt%;

[0012] Color powder 0.5-2wt%;

[0013] Other additives 0.1-1wt%;

[0014] Polypropylene: remaining components.

[0015] In the above-mentioned polypropylene composite material,

[0016] The polypropylene is a composition of copolymerized polypropylene and homopolymerized polypropylene with a melt index of 30 to 100 g / 10 min under the test conditions of 230° C. and 2.16 kg, and the weight ratio is 3:1.

[0017] The continuous glass fiber is an alkali-free glass fiber with a single fiber diameter of 10 to 15 μm and a linear density of 2000 to 2500 tex.

[0018] The high melt strength elastomer is ethylene-octene copolymer, with a Mooney viscosity of ≥30MU at ML1+4, 120°C, and an acceleration of 20mm / s at 200°C. 2 Under the given conditions, the melt strength is ≥35cN.

[0019] The ethylene and acrylate copolymer is one of ethylene-methyl acrylate copolymer and ethylene-butyl acrylate copolymer, and the acrylate copolymer content is ≥25%.

[0020] The rare earth stearate is one of cerium stearate, lanthanum stearate and the like.

[0021] The toner is one of carbon black, zinc sulfide, titanium dioxide, etc. or a combination of two or more.

[0022] The other additives include one or a combination of antioxidants and light stabilizers. The antioxidant is a mixture of 1010 (tetrakis(β-3,5-di-tert-butyl-4-hydroxyphenyl) pentaerythritol), antioxidant 168 (tris(2,4-di-tert-butylphenyl) phosphite), and antioxidant DSTP (dicetadecyl thiodipropionate). The light stabilizer is one or a combination of o-hydroxybenzophenone, benzotriazoles, salicylates, and hindered amines.

[0023] The method for preparing a long glass fiber reinforced polypropylene composite material with good surface appearance and good vibration reduction, noise reduction and low emission for automobile interior decoration comprises the following steps:

[0024] (1) Weigh the raw materials according to the weight ratio: polypropylene, high melt strength elastomer, ethylene-acrylate copolymer, rare earth stearate, color powder, and other additives. Place the weighed raw materials in a high-speed mixer and mix them evenly. Then add them to a twin-screw extruder for melt mixing. The extrusion processing temperature is 220-280℃, and the main engine speed is 300-500rpm. The mixed extruded melt enters a specially structured impregnation mold cavity.

[0025] (2) The continuous glass fiber is synchronously introduced into the impregnation mold cavity, and the surface of the long glass fiber passing through the mold cavity is evenly impregnated with polypropylene resin by a pultrusion process. The impregnated continuous glass fiber is cooled in a water tank, pulled and pelletized to obtain a shock-absorbing, noise-reducing, low-emission long glass fiber reinforced polypropylene composite material with a length of 10-12 mm that can be used in the field of automotive interiors and has a good surface appearance.

[0026] The impregnation mold cavity includes an upper impregnation plate, a lower impregnation plate, and two front and rear fiber inlet orifice plates and a fiber outlet orifice plate, wherein the end faces of the upper impregnation plate and the lower impregnation plate close to each other are semicircular chelating structures; the fiber inlet orifice plate and the fiber outlet orifice plate are provided with a corresponding number of inlet holes and outlet holes; a limiting plate is provided between two adjacent inlet holes to limit the fiber travel path.

[0027] In order to optimize the impregnation effect of long glass fiber in the polypropylene matrix, the length of the upper and lower impregnation plates of the impregnation cavity is 400-800mm, the arc radius of the semicircular chelating structure is 5-20mm, and the spacing width of the limit plates in the glass fiber walking path is 10-40mm.

[0028] The present invention utilizes an impregnation mold cavity designed specifically for the material's properties to provide a better impregnation effect for long glass fibers in a polypropylene matrix. The blending of a high-melt-strength elastomer and an ethylene-acrylate copolymer in a modified formula significantly increases the friction between the glass fiber and polymer chains, as well as between the PP and elastomer chains. This improves the impregnation of the glass fiber in the PP melt, increases the loss modulus of the polypropylene composite, and achieves superior vibration and noise reduction. Because the ethylene-acrylate copolymer exhibits superior heat resistance compared to PP, it not only improves the interfacial bonding between the glass fiber and polymer chains but also optimizes the emission characteristics of the LGF-PP material compared to traditional maleic anhydride grafts. Rare earth stearates significantly enhance the lubrication between polymer chains, improving the impregnation of the glass fiber in the PP and preventing surface agglomeration and appearance defects of the sticky film during subsequent injection molding. Furthermore, rare earth stearates can capture free radicals generated by PP degradation during processing, forming a micro-crosslinked structure, improving the thermal stability of the PP material, and optimizing the emission characteristics of long glass fiber-reinforced PP materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic diagram of the structure of the impregnation mold cavity;

[0030] Figure 2 Schematic diagram of the structure of the upper impregnation plate;

[0031] Figure 3 Schematic diagram of the structure of the lower impregnation plate;

[0032] Figure 4 Schematic diagram of the semicircular chelate structure in the dipping mold cavity;

[0033] In the figure, 1. upper impregnation plate; 2. fiber introduction hole plate; 3. lower impregnation plate; 4. fiber output hole plate; 5. semicircular chelating structure; 6. limiting piece. DETAILED DESCRIPTION

[0034] The present invention can be further described by the following preferred embodiments, but these embodiments are only for illustration and do not limit the scope of the present invention.

[0035] In the composite material formulations of the Examples and Comparative Examples, the copolymerized polypropylene resin was supplied by SK Chemicals under the trade designation BX3900, with a melt flow rate of 60 g / 10 min at 2.16 kg @ 230°C. The homopolymerized polypropylene resin was supplied by Sinopec under the trade designation M60T, with a melt flow rate of 60 g / 10 min at 2.16 kg @ 230°C. The high melt strength elastomer was supplied by Dow Chemical Company under the trade designation 7387. The ethylene-acrylate copolymer was supplied by Dow Chemical Company under the trade designation AC34035, containing 35% butyl acrylate. The rare earth stearate was supplied by Tongrun Nanotechnology, with cerium stearate as the primary component. The toner was carbon black supplied by Cabot Corporation, with a particle size of 15 nm. Antioxidants were supplied by BASF and ICE (UK), with the trade designations Irganox 1010, Irganox 168, and Negonox DSTP. The glass fiber was provided by Chongqing International Fiberglass under the trade name 305K. The maleic anhydride-grafted polypropylene was provided by Jiayirong Company under the trade name CMG9801. The calcium stearate was provided by Jinwo Chemical, and the conventional ethylene-butylene elastomer was provided by Dow Chemical under the trade name 7467.

[0036] Examples A1-A8 are examples, and B1-B3 are comparative examples. The specific formulation ratios are shown in Tables 1 and 2.

[0037] Weigh the raw materials according to the ratios shown in Tables 1 and 2: polypropylene, high melt strength elastomer, ethylene-acrylate copolymer, rare earth stearate, colorant, and other additives. Mix the weighed ingredients in a high-speed blender until uniform, then add them to a twin-screw extruder for melt mixing. The extrusion process temperature is 220-280°C, and the main engine speed is 300-500 rpm. The mixed, extruded melt enters a specially designed impregnation die cavity.

[0038] The continuous glass fiber is synchronously fed into the optimized impregnation cavity, and the pultrusion process is used to evenly impregnate the surface of the long glass fiber passing through the cavity with polypropylene resin. The impregnated continuous glass fiber is cooled in a water tank and then pulled into pellets.

[0039] Mechanical properties: Density is tested according to ISO 1183. Emission characteristics: Pentaphenyltrialdehyde and TV°C are tested using the Yanfeng 100L bag method with a 500cm2 concentration. Vibration and noise reduction performance: Noise reduction index (RPN) is tested according to VDA 230-206. Surface appearance is determined primarily through visual observation.

[0040] Table 1 Distribution ratio of each group of Examples 1-7 (parts by weight)

[0041]

[0042] Table 2 Comparative Examples 1-3: Distribution Ratio (parts by weight)

[0043] Components Comparative Example 1 Comparative Example 2 Comparative Example 3 Polypropylene 72 62 51.5 Conventional elastomer 7467 10 15 Maleic anhydride grafted PP 5 5 10 calcium stearate 1 1 1.5 carbon black 1 1 1 Other additives 1 1 1 Continuous glass fiber 20 20 20

[0044] From the results of Examples 1 to 2, Examples 5 to 6 and Comparative Examples 1 to 3, it can be seen that the addition of cerium stearate rare earth compound can significantly improve the emission characteristics (especially the acetaldehyde content and TV℃ are significantly reduced) and surface appearance of long glass fiber reinforced PP materials. The higher the rare earth compound content, the lower the acetaldehyde and TV℃ content, and the surface floating fibers and glass fiber agglomeration are also significantly improved. Therefore, it is shown that cerium stearate rare earth compound can improve the surface appearance of long glass fiber reinforced PP materials through the lubricating effect, and can also capture the free radicals generated during the high-temperature extrusion process of PP materials, thereby optimizing the emission characteristics of long glass fiber reinforced PP materials. The results of Examples 2 to 3, Examples 6 to 7 and Comparative Examples 1 to 2 show that ethylene-acrylate copolymer can improve the interfacial bonding force between long glass fibers and PP better than maleic anhydride grafted PP, and has a better effect on surface floating fibers and agglomeration (see the surface appearance picture of Example 3). Figure 2) and emission characteristics have been significantly improved (especially the acetaldehyde content and TV℃ are significantly reduced). With the addition and increase of ethylene-acrylate content, the noise reduction index is significantly reduced. Therefore, the vibration reduction and noise reduction effect of ethylene-acrylate copolymer on long glass fiber reinforced PP materials is also significantly better than that of maleic anhydride grafted PP materials. From the results of Examples 3 to 4 and Comparative Examples 1 to 3, it can be seen that with the addition and increase of high melt strength elastomer, the noise reduction index of long glass fiber reinforced PP materials is significantly reduced, and the vibration reduction and noise reduction effect of the material is better, which helps to broaden the application of long glass fiber reinforced PP materials in the field of vibration reduction and noise reduction. The results of Examples 4 to 5 show that the higher the glass fiber content, the increased density, the significantly increased noise reduction index, and the worse the vibration reduction and noise reduction effect. Therefore, long glass fiber reinforced PP materials with high glass fiber content need more vibration reduction and noise reduction. Compared with traditional grafts and elastomers, high melt strength elastomers and ethylene-acrylate copolymers have better vibration reduction and noise reduction effects.

[0045] Table 3 Summary of the density, emission characteristics, noise reduction effect and appearance results of Examples 1-7 and Comparative Examples 1-3.

[0046]

[0047]

[0048] Note: The noise reduction index RPN is the product of the frequency, severity and detection level of an event, which is called the risk coefficient or risk sequence number. The larger the value, the more serious the potential problem.

[0049] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included in the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection defined by the claims.

Claims

1. A long glass fiber reinforced polypropylene composite material with good surface appearance and low emission and shock absorption for automotive interiors, characterized by: It is composed of the following raw materials in percentage by weight: Continuous glass fiber: 5-50wt%; High melt strength elastomer 1-25wt%; Ethylene-acrylate copolymer: 1-15wt%; Rare earth stearate: 0.1-2wt%; Color powder 0.5-2wt%; Other additives 0.1-1wt%; Polypropylene: remaining components.

2. The long glass fiber reinforced polypropylene composite material with good surface appearance for use in the field of automobile interior decoration according to claim 1, characterized in that: The polypropylene is a composition of copolymerized polypropylene and homopolymerized polypropylene with a melt index of 30 to 100 g / 10 min under the test conditions of 230° C. and 2.16 kg, and the weight ratio is 3:

1.

3. The long glass fiber reinforced polypropylene composite material with good surface appearance and good vibration damping, noise reduction and low emission for automotive interior decoration according to claim 1, characterized in that: The continuous glass fiber is an alkali-free glass fiber with a single fiber diameter of 10 to 15 μm and a linear density of 2000 to 2500 tex.

4. The long glass fiber reinforced polypropylene composite material with good surface appearance for use in the field of automobile interior decoration according to claim 1, characterized in that: The high melt strength elastomer is ethylene-octene copolymer, with a Mooney viscosity of ≥30MU at ML1+4, 120°C, and an acceleration of 20mm / s at 200°C. 2 Under the given conditions, the melt strength is ≥35cN.

5. The long glass fiber reinforced polypropylene composite material with good surface appearance for use in the field of automobile interior decoration according to claim 1, characterized in that: The ethylene and acrylate copolymer is one of ethylene-methyl acrylate copolymer and ethylene-butyl acrylate copolymer, and the acrylate copolymer content is ≥25%.

6. The long glass fiber reinforced polypropylene composite material with good surface appearance for use in the field of automobile interior decoration according to claim 1, characterized in that: The rare earth stearate is one of cerium stearate and lanthanum stearate.

7. The long glass fiber reinforced polypropylene composite material with good surface appearance and good vibration damping, noise reduction and low emission for automobile interior decoration according to claim 1, characterized in that: The toner is one of carbon black, zinc sulfide and titanium dioxide or a combination of two or more.

8. The long glass fiber reinforced polypropylene composite material with good surface appearance for use in the field of automobile interior decoration according to claim 1, characterized in that: The other auxiliary agents include one or a combination of antioxidants, light stabilizers, etc.

9. The long glass fiber reinforced polypropylene composite material with good surface appearance for use in the field of automobile interior decoration according to claim 8, characterized in that: The antioxidant is a mixture of 1010 (tetrakis(β-3,5-di-tert-butyl-4-hydroxyphenyl) pentaerythritol), antioxidant 168 (tris(2,4-di-tert-butylphenyl) phosphite) and antioxidant DSTP (dicetadecyl thiodipropionate); the light stabilizer is one or a combination of o-hydroxybenzophenone, benzotriazoles, salicylates and hindered amines.

10. The method for preparing the long glass fiber reinforced polypropylene composite material with good surface appearance and good vibration reduction, noise reduction and low emission for automobile interior decoration according to any one of claims 1 to 9, characterized in that: The steps include: (1) Weighing raw materials according to weight ratio: polypropylene, high melt strength elastomer, ethylene-acrylate copolymer, rare earth stearate, color powder, and other additives; adding the weighed raw materials into a high-speed mixer and mixing them evenly, and then adding them into a twin-screw extruder for melt mixing; extrusion processing temperature 220-280°C, main engine speed 300-500rpm; the mixed extruded melt enters a specially structured impregnation mold cavity; (2) The continuous glass fiber is synchronously introduced into the impregnation mold cavity, and the surface of the long glass fiber passing through the mold cavity is evenly impregnated with polypropylene resin by a pultrusion process. The impregnated continuous glass fiber is cooled in a water tank, pulled and pelletized to obtain a shock-absorbing, noise-reducing, low-emission long glass fiber reinforced polypropylene composite material with a length of 10-12 mm that can be used in the field of automotive interiors and has a good surface appearance.

11. The method for preparing the shock-absorbing, noise-reducing, low-emission long glass fiber reinforced polypropylene composite material for automobile interior with good surface appearance according to claim 10, characterized in that: The impregnation mold cavity includes an upper impregnation plate, a lower impregnation plate, and two front and rear fiber inlet orifice plates and a fiber outlet orifice plate, wherein the end faces of the upper impregnation plate and the lower impregnation plate close to each other are semicircular chelating structures; the fiber inlet orifice plate and the fiber outlet orifice plate are provided with a corresponding number of inlet holes and outlet holes; a limiting plate is provided between two adjacent inlet holes to limit the fiber travel path.

12. The method for preparing the shock-absorbing, noise-reducing, low-emission long glass fiber reinforced polypropylene composite material for automobile interior with good surface appearance according to claim 11, characterized in that: The lengths of the upper and lower impregnation plates of the impregnation cavity are 400-800 mm, the arc radius of the semicircular chelating structure is 5-20 mm, and the spacing width of the limit plates of the glass fiber walking path is 10-40 mm.

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