WO2022105134A1 - Low-density conductive polypropylene composition, preparation method therefor, and application thereof - Google Patents

Abstract

A low-density conductive polypropylene composition, comprising the following components in parts by weight: 80-90 parts of PP resin, 5-15 parts of hollow glass beads, 3-8 parts of MWCNT, and 0.1-3 parts of an auxiliary agent. The selection of hollow glass beads as a dispersing component effectively improves the dispersion of MWCNT in the polypropylene system, so that the surface resistance of the prepared material is in the range of 104-10 2 Ω/sq; in addition, due to the low density of the hollow glass beads, the material exhibits low-density characteristics. Also disclosed are a preparation method for the low-density conductive polypropylene composition, and an application thereof.

Description

[Title of invention formulated by ISA pursuant to Rule 37.2] Low-density conductive polypropylene composition, method for its preparation and application technical field

The invention relates to the field of polymer material modification, in particular to a low-density conductive polypropylene composition suitable for automotive millimeter-wave radar EMI and a preparation method thereof.

Background technique

As a cost-effective general-purpose plastic, polypropylene (PP) has excellent mechanical properties after toughening and modification, and is easy to form and process, and is widely used in home appliances and automotive products.

Millimeter-wave radars will be widely used in automatic cruise (ACC), collision avoidance system (CA) and lane-change assistance systems in future automotive automated driving technologies, and with the development of technology, 77GHz millimeter-wave radars will be widely industrialized and Replacing 24GHz millimeter-wave radar has become the mainstream of automotive millimeter-wave radar applications. In this case, the anti-jamming of radar is particularly important.

The patent with publication number CN 110951164 A uses micro-foaming technology to improve the electrical conductivity of the material, but as we all know, the use of micro-foaming technology will lead to a substantial decrease in the physical properties of the material, which limits its popularization and use to a certain extent. ; The patent with publication number CN 104877232 A uses nanomaterials containing modified carbonized bacterial cellulose to achieve electrical conductivity. At present, the industrialization of multi-walled carbon nanotubes (MWCNT) has greatly reduced the cost of raw materials. The cost reduction is ineffective, and the conductivity achieved is far lower than that of industrialized conductive fillers such as MWCNT and conductive carbon black, and its processing and preparation method is too cumbersome; in the patent with publication number CN 109867859 A, its scheme adopts metal-organic framework. The material MOFs is used as the main conductive filler and one of graphene, carbon black, carbon nanotube, carbon fiber and conductive metal powder is used as the auxiliary conductive filler, and the conductive properties are realized by compounding, but from the data of the examples. , its solution is currently only antistatic level, rather than conductive level.

Multi-walled carbon nanotubes (MWCNTs) have been widely used in the development of conductive materials as a common conductive filler since their industrial production. Its advantages are low price and low addition amount; Due to the strong interaction force and the high flexibility of the molecular chain of polypropylene, it is difficult for polypropylene melt to effectively transmit shear force to effectively disperse MWCNTs during processing, which makes it difficult for polypropylene systems to use MWCNTs as conductive fillers. Achieving the desired high conductivity; usually, even adding an excess of MWCNTs in the polypropylene system can only achieve antistatic effects, and the addition of excess MWCNTs on the one hand leads to a sharp increase in cost, on the other hand, it is a problem of the parts. Appearance deteriorates and mechanical properties deteriorate. Rigid components, usually various fillers, are usually added to the polypropylene system, which is beneficial to transfer the shear of the screw and improve the dispersion of MWCNTs. However, the amount of addition required is usually very high, so the density of the material will also be significantly improved. Under the background of lightweight automobiles, there is still a need in the art to develop a simple and feasible method for preparing low-density conductive polypropylene materials, which is also suitable for automobile interior and exterior trims requiring electromagnetic shielding.

SUMMARY OF THE INVENTION

Based on this, the purpose of the present invention is to overcome the above-mentioned shortcomings of the prior art and provide a low-density conductive polypropylene composition.

In order to achieve the above purpose, the technical solution adopted in the present invention is: a low-density conductive polypropylene composition, comprising the following components in parts by weight: 80-90 parts of PP resin, 5-15 parts of hollow glass beads, 3-8 parts of MWCNT parts and 0.1 to 3 parts of additives.

Preferably, the weight part of the hollow glass microspheres is 5-10 parts, and the weight part of the MWCNT is 3-5 parts.

Preferably, the PP resin is at least one of homopolypropylene and copolymerized polypropylene; the melt mass flow rate of the PP resin at 230° C. and a load of 2.16Kg is 10-100g/10min.

Preferably, the particle size D90 of the hollow glass microbeads is 10-100 μm, and the wall thickness of the hollow glass microbeads is 1-2 μm.

Preferably, the tube diameter of the MWCNT is 8-60 nm, and the tube length of the MWCNT is 20-100 μm.

Preferably, the selected MWCNTs are arrayed tube CNTs or part of arrayed tube CNTs, and the array length of the selected MWCNTs is 2-80 μm.

Preferably, the auxiliary agent is at least one of antioxidant, light stabilizer and lubricant.

More preferably, the antioxidant is at least one of a hindered phenolic antioxidant and a phosphite antioxidant; the light stabilizer is a hindered amine light stabilizer; the lubricant is stearin Zinc acid.

More preferably, the antioxidant is at least one of 1010, 1076, 3114, 168, and PEP-36; the light stabilizer is at least one of UV-3808PP5, LA-402XP, and LA-402AF.

At the same time, the present invention also provides a preparation method of the low-density conductive polypropylene composition. The method comprises the following steps: mixing the components uniformly, adding them into a twin-screw extruder, melting and kneading, and extruding and pelletizing, A low-density conductive polypropylene composition is obtained; wherein, the temperature of melt-kneading is 200-210° C., and the rotational speed of the screw is 350-450 rpm.

In addition, the present invention also provides the application of the low-density conductive polypropylene composition in automobile interior and exterior trim parts with electromagnetic signal shielding.

Compared with the prior art, the beneficial effects of the present invention are:

1) By selecting hollow glass microspheres as the dispersing component, the dispersion of MWCNTs in the polypropylene system is effectively improved, so that the surface resistance of the prepared material is in the range of 10 ⁴ -10 ² Ω/sq; at the same time, due to the hollow glass microspheres The low density characteristic of the material makes the material exhibit the characteristic of low density;

2) The production method of the low-density conductive polypropylene composition of the present invention is simple and easy to implement, and has a high degree of freedom in design;

3) The low-density conductive polypropylene composition of the present invention has very high electrical conductivity, and is suitable for use as an EMI material for automotive interior and exterior trims with EMI characteristics and other applications with EMI requirements.

Detailed ways

In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below with reference to specific embodiments. The following embodiments are only typical examples of the present invention, and the protection scope of the present invention is not limited thereto. In the following examples and comparative examples, the test methods for electrical conductivity are: the surface resistance of the material is tested according to ASTM D4496-2013 and D257-2014 standards; the test standard for impact strength is ISO 527-1-2012; the test for flexural modulus The standard is ISO 178-2010; the reference standard for density testing is ISO 1183-2019.

The main representative materials used in the examples and comparative examples are as follows:

PP resin 1: Copolymerized polypropylene, the melt mass flow rate at 230°C and 2.16Kg load is 40g/10min, Sinopec Maoming;

PP resin 2: Copolymerized polypropylene, the melt mass flow rate at 230°C and 2.16Kg load is 2g/10min, CNOOC Shell;

Hollow glass beads 1: D90 is 75μm, wall thickness is 1μm, 3M company;

Hollow glass beads 2: D90 is 110μm, wall thickness is 1μm, Zhongke Huaxing;

MWCNT 1: tube diameter is 8-15nm, tube length is 20-60μm, array tube, array length is 5-50μm, LG Chem;

MWCNT 2: diameter of 10-30nm, length of 30-45μm, non-array tube, Shandong Dazhan;

MWCNT 3: tube diameter is 12-15nm, tube length is 3-12μm, array tube, array length is 2-8μm, LG Chem;

Filler 1 (talcum powder): the particle size is 1250 mesh, Beihai Group;

Filler 2 (calcium carbonate): fineness 1250 mesh, Jiangsu Yifeng;

Auxiliaries (all are commercially available):

Antioxidants (1010/168);

Light stabilizer (UV-3808PP5);

Lubricant (zinc stearate);

The preparation method of the low-density conductive polypropylene composition is as follows:

The components are mixed uniformly and then added to a twin-screw extruder, melt-kneaded, extruded and pelletized to obtain a low-density conductive polypropylene composition; wherein, the melt-kneading temperature is 200-210° C., and the screw speed is 350 ~450 rpm. EXAMPLES AND COMPARATIVE EXAMPLES According to the formula shown in Table 1, the polypropylene composition was prepared according to the above method, and then the composition was injection-molded into 100mm*100mm*2mm sample pieces and ISO standard mechanical splines.

Examples 1 to 10 and Comparative Examples 1 to 6 are set in this application. The formulations and electrical conductivity of the low-density conductive polypropylene compositions of Examples 1 to 10 are shown in Table 1; The ingredient content and properties are shown in Table 2.

Table 1 Contents of components and conductivity of low-density conductive polypropylene compositions of Examples 1-10

Table 2 Contents of components and conductivity of low-density conductive polypropylene compositions of Comparative Examples 1-6

project	Comparative Example 1	Comparative Example 2	Comparative Example 3	Comparative Example 4	Comparative Example 5	Comparative Example 6
PP resin 1	90	90	90	90	90	90
talcum powder		5	10
calcium carbonate				10
Hollow glass beads 1					18	10
MWCNT1	4	4	4	4	4	2
Antioxidant	0.2	0.2	0.2	0.2	0.2	0.2
light stabilizer	0.2	0.2	0.2	0.2	0.2	0.2
Zinc stearate	0.4	0.4	0.4	0.4	0.4	0.4
Surface resistance (Ω/sq)	6.65E+08	4.89E+06	3.21E+05	8.69E+05	5.33E+05	7.68E+09
Density (kg/m 3 )	0.928	0.964	0.987	0.982	0.945	0.936

It can be seen from the performance data in Table 1 that the electrical conductivity test results of Examples 1 to 8 of the present application are all at the level of 10 ⁴ to 10 ² Ω/sq, and the material density is all lower than 0.95, belonging to low-density and high-conductivity materials.

Comparing the data of Examples 1-2 and Example 6, it is preferred that the addition amount of hollow glass microspheres is 5-10 parts, because when the addition amount of hollow glass microspheres is higher than 10 parts, the hollow glass microsphere powder If the volume ratio of the material is too high, it is easy to cause instability of the extrusion feeding, which will affect the production stability of the material.

The comparison of the data of Examples 1 to 2 and 6 with Comparative Example 1 shows that the use of hollow glass microspheres improves the dispersion of MWCNTs to a great extent, thereby reducing the surface resistance of the material, improving the electrical conductivity, and at the same time, the Density remains low.

The data comparison between Example 1 and Comparative Example 2, as well as the data comparison between Example 2 and Comparative Examples 3 to 4, show that for the same filler fraction, hollow glass microspheres have better dispersion effect on MWCNT, and the material has higher electrical conductivity, while systems using hollow glass microspheres have lower densities.

Comparing Example 2 with Example 3, it can be seen that the PP resin in Example 2 has a melt mass flow rate in the range of 10-100g/10min at 230°C and a load of 2.16Kg, and the PP resin in Example 3 melts. The body mass flow rate is not within the above range, and the surface resistance and density in Example 3 are higher than those in Example 2;

Comparing Example 2 with Example 4, it can be seen that the particle size of the hollow glass microspheres in Example 2 is 10-100 μm, and the wall thickness is 1-2 μm; the particle size and wall thickness of the hollow glass microspheres in Example 4 are not Within the above range, the surface resistance and density in Example 4 are higher than those in Example 2;

Comparing Example 2 with Example 5, it can be seen that the MWCNTs in Example 2 are array tube CNTs or part of array tube CNTs, and the array length of the selected MWCNTs is 2-80 μm; The surface resistance and density in Example 5 were higher than those in Example 2.

Example 2 is compared with Example 9. In Example 9, 8 parts of MWCNTs are used, and the high MWCNT content will make the processing of the material difficult and make the electrical conductivity of the material more unstable. Example 2 phase It has lower conductivity than Example 9.

Comparing Example 2 with Example 10, the tube length of the MWCNT in Example 10 is not in the range of "20-100 μm", and the conductivity achieved in Example 10 is lower than that in Example 2.

Comparing Example 2 with Comparative Examples 5 and 6, it can be seen that in Comparative Example 5, hollow glass beads are contained, but the content is outside the range of 5-15 parts, and the content of MWCNT in Comparative Example 6 is outside the range of 3-8 parts; Comparative Example 5 The surface resistance and density of 6 and 6 are higher than those of Example 2.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the protection scope of the present invention. Although the present invention is described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that, The technical solutions of the present invention may be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention.

Claims (10)

1. A low-density conductive polypropylene composition is characterized in that it comprises the following components by weight: 80-90 parts of PP resin, 5-15 parts of hollow glass microspheres, 3-8 parts of MWCNT and 0.1-3 parts of auxiliary.
2. The low-density conductive polypropylene composition according to claim 1, wherein the weight part of the hollow glass microspheres is 5-10 parts, and the weight part of the MWCNT is 3-5 parts.
3. The low-density conductive polypropylene composition according to claim 1 or 2, wherein the PP resin is at least one of homopolypropylene and copolymerized polypropylene; The melt mass flow rate under load is 10-100 g/10min.
4. The low-density conductive polypropylene composition according to claim 1 or 2, wherein the particle size D90 of the hollow glass microspheres is 10-100 μm, and the wall thickness of the hollow glass microspheres is 1-2 μm.
5. The low-density conductive polypropylene composition according to claim 1 or 2, wherein the tube diameter of the MWCNT is 8-60 nm, and the tube length of the MWCNT is 20-100 μm.
6. The low-density conductive polypropylene composition according to claim 1 or 2, wherein the selected MWCNTs are array tube CNTs or partial array tube CNTs, and the array length of the selected MWCNTs is 2-80 μm.
7. The low-density conductive polypropylene composition according to claim 1 or 2, wherein the auxiliary agent is at least one of an antioxidant, a light stabilizer, and a lubricant.
8. The low-density conductive polypropylene composition according to claim 7, wherein the antioxidant is at least one of hindered phenol antioxidants and phosphite antioxidants; the light stabilizer It is a hindered amine light stabilizer; the lubricant is zinc stearate.
9. A method for preparing a low-density conductive polypropylene composition according to any one of claims 1 to 8, characterized in that the method comprises the following steps: mixing the components uniformly, then adding them into a twin-screw extruder, and carrying out melt mixing. kneading, extruding and pelletizing to obtain a low-density conductive polypropylene composition; wherein, the temperature of melt-kneading is 200-210° C., and the rotational speed of the screw is 350-450 rpm.
10. An application of the low-density conductive polypropylene composition according to any one of claims 1 to 8 in automobile interior and exterior trim parts with electromagnetic signal shielding.