WO2021129115A1 - Polypropylene composite material and preparation method therefor - Google Patents

Abstract

The present invention provides a low-dielectric polypropylene composite material. The addition of a certain amount of carbon black having a nitrogen adsorption specific surface area greater than or equal to 300 m ²/g can lower the use amount of carbon black, so as to prevent the increase in the dielectric constant and dielectric loss caused by the excessive addition of the carbon black. The polypropylene composite material can be used for automotive interior and exterior parts with dielectric requirements.

Description

Polypropylene composite material and preparation method thereof Technical field

The invention relates to the technical field of polymer materials, in particular to a low-dielectric polypropylene composite material and a preparation method thereof.

Background technique

As a cost-effective general-purpose plastic, polypropylene has high strength, high toughness, excellent mechanical properties, chemical resistance, and high heat resistance after modification. It is widely used in home appliances and automotive products, and is used as a decorative part of polypropylene products. Need to go through color matching treatment, among which the color matching of automobile products is mostly black, and the black color of polypropylene is mainly realized by adding carbon black, which also brings the influence of carbon black dispersion on the blackness and gloss of the product. .

However, the dispersibility of carbon black is not good because it is easy to agglomerate during the melting and mixing of polypropylene. Generally, those skilled in the art believe that carbon black with smaller fineness (large specific surface area) is easier to agglomerate, so the carbon black used Often the nitrogen adsorption specific surface area is less than 250m ² /g, which leads to the need to add an excessive amount of carbon black to the color matching of high-blackness products, and introduces the problem of dispersibility, affects the gloss of the material, and makes the dielectric constant of the material And the dielectric loss will rise more.

Patent CN 101704974A discloses a method for preparing high-gloss polypropylene containing carbon black colorant, which adopts a method of pre-dispersing carbon black and dispersant to improve the dispersibility of carbon black, and the selected carbon black has a particle size of 13 -70 microns, which cannot achieve high black color matching, and is limited to ordinary products that do not require high blackness; in addition, CN 106854308 A discloses a method for preparing high-gloss black impact polypropylene, which also does not limit carbon black. According to the published L value data, it can be inferred that the nitrogen adsorption specific surface area of the carbon black contained in the selected color masterbatch should fall within the ^{range of 200-250m 2} /g. At the same time, it can be seen from the examples. If the L value is lower than 25, the addition amount of black masterbatch is as high as 3-4%. Such a high addition ratio will inevitably cause carbon black dispersion defects. At the same time, the addition of high-content color masterbatch will cause polypropylene to mediate. Deterioration of electrical performance.

Summary of the invention

The purpose of the present invention is to provide a polypropylene composite material, which has a low dielectric constant and high gloss under the premise of a high black color matching.

Another object of the present invention is to provide a method for preparing the above-mentioned low-dielectric polypropylene composite material.

The present invention is realized through the following technical solutions:

A low-dielectric polypropylene composite material, in parts by weight, comprising the following components:

100 parts of homopolypropylene resin;

Carbon black 1-3 copies;

Filler 0-30 copies;

The nitrogen adsorption specific surface area of carbon black is ≥300m ² /g.

Preferably, the carbon black has a nitrogen adsorption specific surface area ≥ 350 m ² /g.

The dielectric constant of the polypropylene composite material of the present invention is lower than 2.40.

The said homopolymerized polypropylene has a melt mass flow rate of 1-100g/10min at 230°C and a load of 2.16Kg.

The nitrogen adsorption specific surface area mainly reflects the particle size information of carbon black.

In order to stiffen polypropylene composites, a certain amount of fillers are often added. However, commonly used fillers (such as talc powder, mica powder, etc.) not only easily cover the carbon black, but also reduce the surface gloss of the polypropylene resin, and reduce the dielectric properties of the composite material to varying degrees. It is found through experiments that calcium carbonate and barium sulfate have a low coverage rate for carbon black. Therefore, it can not only ensure the blackness of the filled polypropylene composite material, but also ensure that the surface gloss does not drop significantly, and it can also improve the mediation caused by the addition of fillers. Decline in electrical performance.

Preferably, the filler is selected from at least one of calcium carbonate and barium sulfate.

More preferably, it is selected from calcium carbonate.

The meshes of the calcium carbonate and barium sulfate are less than 5000 meshes.

A certain amount of toughening agent can be added, based on parts by weight, and 0-25 parts of toughening agent; the toughening agent is selected from at least one of POE, SEBS, and EPDM.

POE (Polyolefin elastomer) is a polyolefin elastomer;

SEBS (Styrene ethylene butene styrene block copolymer) is a linear triblock copolymer with polystyrene as the terminal block and ethylene-butene copolymer obtained by hydrogenation of polybutadiene as the middle elastic block;

EPDM (Ethylene Propylene Diene Monomer) is also called EPDM;

In order to improve processing performance or light stability performance, 0-2 parts by weight of auxiliary agent is also included; the auxiliary agent is selected from at least one of antioxidants, lubricants, and light stabilizers.

The antioxidant can be hindered phenol and phosphite antioxidants, specifically one of 1010, 1076, 3114, 168, PEP-36 or a mixture of two or more;

The light stabilizer can be a hindered amine light stabilizer, specifically one or a mixture of two or more of UV-3808PP5, LA-402XP, and LA-402AF;

The lubricant can be one or a mixture of two or more of silicones, esters, amides, polyethylenes, stearic acids, fatty acids and esters;

The preparation method of the above-mentioned polypropylene composite material includes the following steps: firstly mix carbon black with 1-5 times the weight of polypropylene to obtain carbon black/polypropylene particles, and combine the carbon black/polypropylene particles with the remaining After the polypropylene and other components are mixed uniformly, they are added to the twin-screw extruder for melt mixing. The melt mixing temperature is 170°C-220°C, the screw speed is 350-450 rpm, and the extrusion granulation is obtained. Low dielectric polypropylene composite material; the original screw is set with high shear.

The high-shear setting can better disperse the carbon black in the polypropylene resin matrix to ensure high black chromaticity and low dielectric properties with a small amount of carbon black added.

Compared with the prior art, the present invention has the following beneficial effects:

The prior art mainly uses carbon black with a nitrogen adsorption specific surface area of less than 250m ² /g as the addition of black pigments. However, the blackening effect of this type of carbon black is not good, and a large amount of addition is required to obtain high black color matching. This will lead to a significant increase in the dielectric constant and dielectric loss of the resin matrix. By adopting carbon black with nitrogen adsorption specific surface area ≥ 300m ² /g, the present invention can obtain high black color matching with a small amount of addition, and has less agglomeration and low dielectric constant. It is prepared by high shear and is also sufficient Toner is sheared and dispersed.

Furthermore, it is found through experiments that the addition of calcium carbonate and barium sulfate will not cover the carbon black in the resin matrix, and will not greatly reduce the surface gloss of the resin matrix.

Detailed ways

The present invention will be described in detail below in conjunction with specific embodiments. The following examples will help those skilled in the art to further understand the present invention, but do not limit the present invention in any form. It should be pointed out that for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

The raw materials used in the present invention are derived from commercially available products:

Polypropylene resin A: Lanzhou Petrochemical PP H9018, homopolypropylene;

Polypropylene resin B: CNOOC and Shell EP548R, copolymerized polypropylene;

Carbon black A: The nitrogen adsorption specific surface area is approximately equal to 375m ² /g;

Carbon black B: The nitrogen adsorption specific surface area is approximately equal to 300m ² /g;

Carbon black C: The nitrogen adsorption specific surface area is approximately equal to 270m ² /g;

Carbon black D: The nitrogen adsorption specific surface area is approximately equal to 195m ² /g;

Barium sulfate: 1250 mesh;

Calcium carbonate: 1250 mesh;

Talc: 1250 mesh;

Mica powder: 1250 mesh;

POE: Dow ENGAGE 8137;

Lubricant: stearic acid lubricant;

Antioxidant: Antioxidant 168;

The preparation method of the polypropylene composite material of the examples and comparative examples: firstly mix carbon black and 1-5 times the weight of polypropylene to obtain carbon black/polypropylene particles, and combine the carbon black/polypropylene particles with the remaining Polypropylene, POE, barium sulfate, lubricants, and antioxidants are mixed evenly and then added to the twin-screw extruder for melting and mixing. The melting and mixing temperature is 170°C-220°C, and the screw speed is 350-450 rpm. , Extrusion and granulation to obtain low-dielectric polypropylene composite material; the original screw adopts high-shear setting.

Various performance test methods:

Test sample preparation method: The modified particles are injection molded through a double-sided mirror polished mold to prepare a 10mm*5mm*1.5mm sample.

L value: Put the sample in X-Rite Color-Eye 7000A color difference meter, set SCI mode, and perform L value test to evaluate the blackness of the material (the lower the L value, the higher the blackness).

60° Gloss: Test 60° gloss with BYK Pvlt0925 gloss meter.

Dielectric constant: The N5225A vector network analyzer uses the transmission line reflection method and sets the frequency 76-77GHz to test the dielectric constant and loss tangent of the sample.

Table 1: The distribution ratio of each group and the performance test results of the polypropylene composite material of the embodiment

To	Example 1	Example 2	Example 3	Example 4	Example 5
Polypropylene resin A	100	100	100	100	100
Carbon black A	1	1.5	2.5	To	1.5
Carbon black B	To	To	To	1.5	To
Barium sulfate	20	20	20	20	To
Calcium carbonate	To	To	To	To	20
POE	4	4	4	4	4
Lubricant	0.4	0.4	0.4	0.4	0.4
Antioxidant	0.4	0.4	0.4	0.4	0.4
L value	23.71	23.43	23.06	23.97	23.38
60° gloss	85.3	85.4	85.7	85.3	85.6
Dielectric constant	2.34	2.35	2.38	2.36	2.34
Loss tangent	0.0084	0.0088	0.0094	0.0089	0.0087

It can be seen from Examples 1-3 that the increase in the amount of carbon black whose nitrogen adsorption specific surface area is approximately equal to 375 m ² /g increases the blackness, but the increase in dielectric constant and loss tangent is not large.

It can be seen from Example 2/4 that carbon black with a nitrogen adsorption specific surface area greater than 350 m ² /g is preferred.

Continued Table 1:

To	Example 6	Example 7	Example 8
Polypropylene resin A	100	100	100
Carbon black A	1.5	1.5	1.5
Barium sulfate	To	To	To
Calcium carbonate	To	To	To
Mica powder	To	20	To
talcum powder	To	To	20

POE	4	4	4
Lubricant	0.4	0.4	0.4
Antioxidant	0.4	0.4	0.4
L value	23.06	24.53	24.37
60° gloss	88.9	78.3	79.3
Dielectric constant	2.28	2.40	2.38
Loss tangent	0.0024	0.0096	0.0095

It can be seen from Example 2/5/6/7/8 that the addition of inorganic fillers will cover the carbon black, resulting in a decrease in blackness and gloss. However, it can be seen by comparison that the preferred barium sulfate and calcium carbonate of the present invention can reduce the coverage of carbon black and improve the reduction of gloss; calcium carbonate is more preferred.

Table 2: The distribution ratio of each group and the performance test results of the polypropylene composite material of the comparative example

To	Comparative example 1	Comparative example 2	Comparative example 3	Comparative example 4	Comparative example 5
Polypropylene resin A	100	100	100	100	To
Polypropylene resin B	To	To	To	To	100
Carbon black A	To	To	To	To	1.5
Carbon black C	1.5	3	To	To	To
Carbon black D	To	To	1.5	3	To
Barium sulfate	20	20	20	20	20
Mica powder	To	To	To	To	To
talcum powder	To	To	To	To	To
POE	4	4	4	4	4
Lubricant	0.4	0.4	0.4	0.4	0.4
Antioxidant	0.4	0.4	0.4	0.4	0.4
L value	24.84	24.25	25.16	24.86	23.82
60° gloss	85.4	85.1	85.2	84.9	52.6
Dielectric constant	2.37	2.45	2.37	2.46	2.36
Loss tangent	0.0090	0.0124	0.0089	0.0121	0.0086

It can be seen from Comparative Examples 1-4 that carbon black with a nitrogen adsorption specific surface area of less than 300 m ² /g has a low blackening effect, and the blackness can only be improved by increasing the amount of carbon black. However, this will cause a decrease in dielectric properties (increased dielectric constant and loss tangent value).

Claims (10)

1. A polypropylene composite material, characterized in that, in parts by weight, it comprises the following components:

   100 parts of homopolypropylene resin;

   Carbon black 1-3 copies;

   The nitrogen adsorption specific surface area of carbon black ≥300m ² /g;

   Filler 0-30 copies.
2. The polypropylene composite material of claim 1, wherein the carbon black has a nitrogen adsorption specific surface area ≥ 350 m ² /g.
3. The polypropylene composite material of claim 1, wherein the dielectric constant of the polypropylene composite material is lower than 2.40.
4. The polypropylene composite material according to claim 1, wherein the homopolymer polypropylene has a melt mass flow rate of 1-100 g/10min at 230°C and a load of 2.16Kg.
5. The polypropylene composite material of claim 1, wherein the filler is selected from at least one of calcium carbonate and barium sulfate.
6. The polypropylene composite material of claim 5, wherein the filler is selected from calcium carbonate.
7. The polypropylene composite material of claim 5, wherein the meshes of the calcium carbonate and barium sulfate are less than 5000 meshes.
8. The polypropylene composite material according to claim 1, characterized in that it further comprises 0-25 parts by weight of a toughening agent; the toughening agent is selected from at least one of POE, SEBS, and EPDM .
9. The polypropylene composite material according to claim 1, characterized in that it further comprises 0-2 parts by weight of auxiliary agent; said auxiliary agent is selected from antioxidants, lubricants, and light stabilizers. At least one.
10. The preparation method of polypropylene composite material according to any one of claims 1-9, characterized in that it comprises the following steps: first mixing carbon black with 1-5 times the weight of polypropylene to obtain carbon black/ Polypropylene pellets, mix the carbon black/polypropylene pellets with the remaining polypropylene and other components evenly and then add them to the twin-screw extruder for melt mixing. The melt mixing temperature is 170℃-220℃, and the screw speed 350-450 rpm, extrusion granulation to obtain polypropylene composite material; the original screw is set with high shear.