CN113861559A

CN113861559A - Heat-conducting polypropylene material and preparation method and application thereof

Info

Publication number: CN113861559A
Application number: CN202111158158.8A
Authority: CN
Inventors: 杨泽; 尹朝清; 陈平绪; 叶南飚; 杨磊; 张爽爽; 王亚南; 周杰; 王培武
Original assignee: Shanghai Kingfa Science and Technology Co Ltd; Jiangsu Kingfa New Material Co Ltd
Current assignee: Shanghai Kingfa Science and Technology Co Ltd; Jiangsu Kingfa New Material Co Ltd
Priority date: 2021-09-30
Filing date: 2021-09-30
Publication date: 2021-12-31
Anticipated expiration: 2041-09-30
Also published as: CN113861559B

Abstract

The invention discloses a heat-conducting polypropylene material and a preparation method and application thereof, wherein the heat-conducting polypropylene material comprises the following components in parts by weight: 60-83 parts of first polypropylene resin, 4-10 parts of second polypropylene resin, 2-10 parts of polyethylene resin, 1-5 parts of compatilizer, 3-8 parts of foam metal, 10-20 parts of heat-conducting filler and 0.2-1 part of passivator. According to the invention, the foam metal, the heat-conducting filler and the melt-blown polypropylene are added to modify the polypropylene material, so that under the synergistic effect of the foam metal, the heat-conducting filler and the melt-blown polypropylene, the heat-conducting property of the material is greatly improved, the material is lightened, and the polypropylene material has excellent electrical insulation property and mechanical property.

Description

Heat-conducting polypropylene material and preparation method and application thereof

Technical Field

The invention belongs to the technical field of modified plastics, and particularly relates to a heat-conducting polypropylene material as well as a preparation method and application thereof.

Background

The heat conduction material has wide application in various fields of national defense industry and national economy, and the traditional heat conduction material is generally a metal material, but the application of the metal material is limited due to poor corrosion resistance of the metal material. The polymer material has the characteristics of light weight, corrosion resistance, easiness in processing and forming, good electrical insulation performance, excellent mechanical property and fatigue resistance and the like, and plays an important role in the fields of information industry and the like at present. However, since most of the polymer materials are poor conductors and have extremely low thermal conductivity, for example, the thermal conductivity of polypropylene (PP) is only about 0.2W/(m · K), and the thermal conductivity of nylon 6(PA6) is only about 0.25W/(m · K). However, in the mechanical field, the thermal conductivity of the sheet is generally required to be 1.3 to 2W/(mK), and in the field of electronic products such as mobile phones, the chip content of which is increasing, the thermal conductivity is generally required to be 5W/(mK) or more.

In order to improve the thermal conductivity of the polymer material, the prior art generally adopts a method of adding a metal oxide with better thermal conductivity, for example, CN112029275A discloses that the thermal conductivity of PA is improved by adding zinc oxide, magnesium oxide, aluminum oxide, boron nitride, zinc nitride, aluminum nitride, magnesium hydroxide, aluminum hydroxide, silicon carbide or graphite. However, this method greatly reduces the mechanical properties of the material due to the excessive amount of the heat transfer medium required to be added.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention aims to provide a heat-conducting polypropylene material and a preparation method and application thereof.

In order to realize the purpose, the technical scheme adopted by the invention is as follows:

a heat-conducting polypropylene material comprises the following components in parts by weight: 60-83 parts of first polypropylene resin, 4-10 parts of second polypropylene resin, 2-10 parts of polyethylene resin, 1-5 parts of compatilizer, 3-8 parts of foam metal, 10-20 parts of heat-conducting filler and 0.2-1 part of passivator.

Further, the first polypropylene resin is at least one of homo-polypropylene, co-polypropylene and random polypropylene, and the melt flow rate of the first polypropylene resin is 8-70 g/10min under the test condition of 230 ℃/2.16 kg.

Further, the second polypropylene resin is melt-blown polypropylene, and the melt flow rate of the second polypropylene resin is 1200-2500 g/10min under the test condition of 230 ℃/2.16 kg.

Preferably, the polyethylene resin is at least one of high density polyethylene, low density polyethylene and linear low density polyethylene; in view of processability, linear low density polyethylene is more preferably used.

Preferably, the compatilizer is a graft modified polymer and comprises at least one of PP grafted maleic anhydride, POE grafted maleic anhydride and PP grafted dibutyl maleate.

Preferably, the metal foam is at least one of reduced iron powder and iron foam, but not limited to the above two.

Preferably, the porosity of the metal foam is 60% to 75%. The porosity of the foam metal is too small, collapse easily occurs, and electric conduction easily occurs; too high porosity will reduce the thermal conductivity.

Preferably, the thermally conductive filler includes at least one of metal oxide (e.g., zinc oxide, magnesium oxide, etc.), metal hydroxide (e.g., aluminum hydroxide, magnesium hydroxide).

Preferably, the weight ratio of the foam metal to the heat-conducting filler is 0.2-0.5; more preferably 0.3 to 0.4. The polypropylene material has better comprehensive performance in the proportion.

Preferably, the passivating agent is antioxidant 1024. Generally, the addition of a metal component accelerates the degradation of the plastic, while the addition of the passivating agent prevents the metal from accelerating the degradation of the plastic.

Compared with heat conducting fillers such as metal oxides, metal hydroxides and the like, the foam metal used in the invention has higher electron conduction speed and higher heat conduction. Therefore, the heat-conducting property of the polypropylene material can be greatly improved by adding the foam metal, the addition amount of the heat-conducting filler in the polypropylene material can be reduced, the material is lightened, the influence of the low-ductility filler on the mechanical property of the material is reduced, and the toughness of the material is better maintained. In addition, the foam metal has rigidity and toughness, so that the rigidity of the material is improved to a certain extent while the material has better toughness. However, if only the metal foam is added, the polypropylene material is easy to form a conductive path when the porous structure is damaged. The existence of the heat-conducting filler can form a certain blocking effect and improve the electrical insulation performance of the polypropylene material, so that the effect of simultaneously adding the foam metal and the heat-conducting filler is better. Furthermore, a proper amount of melt-blown polypropylene with the parameters can be added to completely fill the residual gaps of the foam metal, so that the heat-conducting property of the polypropylene material can be further improved, a more stable blocking effect can be formed, and the polypropylene material can be better prevented from forming a conductive path.

The polyethylene resin has low melting point and is easy to process, the polyethylene resin serving as the auxiliary resin can improve the dispersibility of raw material components and improve the mechanical property of the polypropylene material, and particularly, when the polypropylene resin is prepared by using a master batch method, the internal mixer can be used for preparing foam metal master batches, so that excessive extrusion of a double-screw extruder on foam metal is avoided, and the porous structure of the foam metal is better retained.

The invention also provides a preparation method of the heat-conducting polypropylene material, which comprises the following three steps:

method one (direct processing method): mixing the first polypropylene resin, the second polypropylene resin, the polyethylene resin, the compatilizer, the foam metal, the heat-conducting filler and the passivator, adding the mixture into a double-screw extruder for granulation, cooling and cutting to obtain the heat-conducting polypropylene material.

Method two (half side feeding method): mixing the first polypropylene resin, the second polypropylene resin, the polyethylene resin, the compatilizer, the heat-conducting filler and the passivator, adding the mixture into a double-screw extruder for granulation, adding the foam metal from a side feeding port, cooling and cutting to obtain the heat-conducting polypropylene material. In order to better retain the structure of the metal foam, the side feeding port needs to be opened at the rear position of the extruder to reduce the time for the metal foam to remain in the screw cylinder.

Method three (master batch external mixing method): (1) adding polyethylene resin, second polypropylene resin, a compatilizer, foam metal and a passivating agent into an internal mixer, heating and mixing, and extruding and granulating by a single-screw extruder to obtain foam metal master batches; (2) mixing the first polypropylene resin and the heat-conducting filler, adding the mixture into a double-screw extruder for granulation, and cooling and cutting the mixture to obtain heat-conducting filler master batches; (3) and mixing the foam metal master batch and the heat-conducting filler master batch to obtain the heat-conducting polypropylene material which can be directly used for injection molding.

In the preparation method, the preparation method preferably adopts a three-master-batch external mixing method, the method can reduce the shearing of the screw on the foamed metal, better protect the porous structure of the foamed metal, ensure the electrical insulation performance of the polypropylene material to be better, ensure the thermal conductivity coefficient of the polypropylene material to reach more than 5W/(m.K), and meet the thermal conductivity requirements of most electronic components.

The invention also provides application of the heat-conducting polypropylene material in preparation of electronic components.

Compared with the prior art, the invention has the beneficial effects that: according to the invention, the foam metal, the heat-conducting filler and the melt-blown polypropylene are added to modify the polypropylene material, so that under the synergistic effect of the foam metal, the heat-conducting filler and the melt-blown polypropylene, the heat-conducting property of the material is greatly improved, the material is lightened, and the polypropylene material has excellent electrical insulation property and mechanical property, and has a good application prospect in the fields of electronic components and the like.

Detailed Description

The present invention will be described in detail with reference to specific embodiments in order to make the above objects, features and advantages more comprehensible. It is apparent that the following examples are only a part of the embodiments of the present invention, and not all of them. It should be understood that the embodiments of the present invention are only for illustrating the technical effects of the present invention, and are not intended to limit the scope of the present invention. The methods employed in the examples of the present invention are all conventional in the art, and the equipment, reagents, and starting materials used therein are commercially available, unless otherwise specified.

The following description of the raw materials used in the present invention is made, but not limited to, these materials:

first, examples 1 to 6 and comparative examples 1 to 4 respectively provide a polypropylene material, and the raw material formula of the polypropylene material is shown in the following table 1:

TABLE 1

Note: in the table, "-" indicates that the component was not added.

The polypropylene materials of examples 1-6 were prepared by a half-side feeding method, comprising the following steps: mixing the components except for the foam iron powder or the reduced iron powder, adding the mixture into a double-screw extruder for granulation, wherein the foam iron powder or the reduced iron powder is prepared from the following components in a ratio of 40: adding the mixture into a side feeding port at the 6 th section of the 1 twin-screw extruder, cooling and cutting to obtain the polypropylene material. Wherein the temperature of the double-screw extruder from the first zone to the tenth zone is as follows in sequence: 160 ℃, 180 ℃, 190 ℃, 220 ℃, 230 ℃, 220 ℃ and 210 ℃.

The polypropylene materials of comparative examples 1 to 4 were prepared according to the preparation methods of examples 1 to 6.

In order to compare the influence of the preparation method on the material performance, the invention also adopts a direct processing method and a master batch external mixing method to prepare the polypropylene material according to the formula of the example 1.

Wherein, the direct processing method comprises the following steps: all components were mixed according to the formulation of example 1, pelletized in a 40:1 twin screw extruder, cooled and cut to produce a polypropylene material designated product 2. Wherein the temperature of the double-screw extruder from the first zone to the tenth zone is as follows in sequence: 160 ℃, 180 ℃, 190 ℃, 220 ℃, 230 ℃, 220 ℃ and 210 ℃.

The master batch external mixing method comprises the following steps:

(1) preparing a foam metal master batch: adding polyethylene resin, second polypropylene resin, a compatilizer, foam metal and a passivating agent into an internal mixer, heating and mixing, and extruding and granulating by a single-screw extruder to obtain foam metal master batches; the process conditions of the internal mixer are 170 ℃, the internal mixing is carried out for 10-15 min, and extrusion granulation is carried out for 2-3 min after the current is stabilized; the temperature of the single-screw extruder from the first zone to the sixth zone is 170 ℃, 180 ℃ and 170 ℃ in sequence;

(2) preparing heat-conducting filler master batch: mixing the first polypropylene resin and the heat-conducting filler, adding the mixture into a double-screw extruder for granulation, and cooling and cutting the mixture to obtain heat-conducting filler master batches; the temperature of the twin-screw extruder from the first zone to the tenth zone is as follows: 170 ℃, 190 ℃, 220 ℃, 240 ℃, 250 ℃, 240 ℃ and 220 ℃;

(3) and mixing the foam metal master batch and the heat-conducting filler master batch to obtain the polypropylene material which can be directly used for injection molding and is marked as a product 3.

The polypropylene material prepared using the half-side feed method for the formulation of example 1 is designated product 1.

Performance testing

The polypropylene materials prepared in the above examples and comparative examples were subjected to performance tests, and the relevant performance test standards or methods were as follows:

tensile strength: dumbbell-shaped splines which meet GB/T1040.1-2006;

impact strength: molding a notch spline by injection, wherein the notch is A-shaped and meets GB/T1843-;

coefficient of thermal conductivity: a square plate of 100mm × 100mm × 3mm, which meets GB/T10294-;

surface resistance: a square plate of 100mm × 100mm × 3mm, which meets GB/T1410-;

density: the impact spline test is adopted to meet GB/T1033-.

The test results are shown in table 2:

TABLE 2

Note: when the heat conductivity coefficient reaches more than 5W/(m.K), the heat conductivity requirement of the electronic products with increasingly increased chip content such as mobile phones and the like at present can be met; the surface resistance reaches 1 multiplied by 10⁶When the Ohm is higher, the use safety is better, otherwise, a conductive path is easily formed, and the electronic component is broken down.

And (4) analyzing results: it can be seen from the products 1 to 3 in the embodiment 1 that the differences in the preparation methods lead to differences in the properties of the prepared polypropylene material, and when the polypropylene material is prepared by the masterbatch external mixing method, the material has the greatest surface resistance and the best electrical insulation property while the thermal conductivity is improved, and the mechanical property and the thermal conductivity can meet the application requirements of electronic components, so that the polypropylene material is preferably prepared by the masterbatch external mixing method. Between the product 1 of the embodiment 1 and the embodiments 2 to 3, the embodiment 2 is optimal in both the thermal conductivity and the electrical insulation performance, and is also good in mechanical property, so the embodiment 2 is taken as a preferred formula. Comparing product 1 with example 4, it can be seen that the different kinds of the first polypropylene resin also affect the mechanical properties and the electrical insulation properties of the material, which depend on the characteristics of the first polypropylene resin itself, so that different kinds of the first polypropylene resin can be selected according to the product performance requirements and applied to different products. From comparative examples 1-4, it can be seen that only when the foamed metal, the heat-conducting filler and the melt-blown polypropylene are added to modify the polypropylene material, the material can give consideration to both the heat-conducting property and the electrical insulation property, and the mechanical property can be improved to a certain extent. It can also be seen from product 1 and comparative example 3 that replacing part of the heat conductive filler with foam metal can reduce the density of the material and make the material lightweight. It can also be seen from example 6 that example 6 uses a foamed iron powder B having a relatively low porosity (50%), resulting in a material having a reduced surface resistance and a reduced electrical insulation performance.

Secondly, in order to investigate the influence of the ratio of the foam metal to the heat-conducting filler on the performance of the polypropylene material, test groups 1-4 in Table 3 are designed, wherein the foam metal is foam iron powder, and the heat-conducting filler is formed by mixing zinc oxide and aluminum hydroxide in a weight ratio of 1: 1. The PP materials of the test groups 1-4 are prepared by a half-side feeding method according to the formula of the example 2, wherein the total adding amount of the foamed iron powder and the heat-conducting filler is 22 parts, and the types and adding amounts of other components are the same as those of the example 2.

TABLE 3

Group of	Foam metal heat-conducting filler (weight ratio)
		Test group 1	0.2
Test group 2	0.3
		Test group 3	0.4
Test group 4	0.5

The PP material prepared above was subjected to a performance test, and the results are shown in Table 4:

TABLE 4

As can be seen from the data in the table above, as the ratio of the content of the foam metal increases, the thermal conductivity of the material gradually increases, but the surface resistance also gradually decreases; when the weight ratio of the foam metal to the heat-conducting filler is 0.2-0.5, the heat-conducting property, the electric insulation property and the mechanical property of the material can meet the use requirements of most electronic components, and particularly when the weight ratio of the foam metal to the heat-conducting filler is 0.3-0.4, the heat-conducting property and the electric insulation property of the material can reach better balance.

Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention and not for limiting the protection scope of the present invention, and although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. The heat-conducting polypropylene material is characterized by comprising the following components in parts by weight: 60-83 parts of first polypropylene resin, 4-10 parts of second polypropylene resin, 2-10 parts of polyethylene resin, 1-5 parts of compatilizer, 3-8 parts of foam metal, 10-20 parts of heat-conducting filler and 0.2-1 part of passivator, wherein the first polypropylene resin is at least one of homo-polypropylene, co-polypropylene and random polypropylene, the melt flow rate of the first polypropylene resin is 8-70 g/10min under the test condition of 230 ℃/2.16kg, the second polypropylene resin is melt-blown polypropylene, and the melt flow rate of the second polypropylene resin is 1200-2500 g/10min under the test condition of 230 ℃/2.16 kg.

2. The thermally conductive polypropylene material according to claim 1, wherein the polyethylene resin is at least one of high density polyethylene, low density polyethylene, and linear low density polyethylene.

3. The thermally conductive polypropylene material of claim 1, wherein the metal foam is at least one of reduced iron powder and foamed iron powder.

4. The thermally conductive polypropylene material of claim 1, wherein the metal foam has a porosity of 60% to 75%.

5. The thermally conductive polypropylene material of claim 1, wherein the thermally conductive filler comprises at least one of a metal oxide and a metal hydroxide.

6. The heat conductive polypropylene material of claim 1, wherein the weight ratio of the foamed metal to the heat conductive filler is 0.2 to 0.5.

7. The thermally conductive polypropylene material of claim 1, wherein the compatibilizer is a graft modified polymer comprising at least one of PP-grafted maleic anhydride, POE-grafted maleic anhydride, and dibutyl PP-grafted maleic anhydride.

8. The thermally conductive polypropylene material of claim 1, wherein the passivating agent is antioxidant 1024.

9. The method for preparing the heat-conducting polypropylene material according to any one of claims 1 to 8, comprising the following steps:

mixing a first polypropylene resin, a second polypropylene resin, a polyethylene resin, a compatilizer, a foam metal, a heat-conducting filler and a passivating agent, adding the mixture into a double-screw extruder for granulation, cooling and cutting to obtain the heat-conducting polypropylene material;

or mixing the first polypropylene resin, the second polypropylene resin, the polyethylene resin, the compatilizer, the heat-conducting filler and the passivator, adding the mixture into a double-screw extruder for granulation, adding foam metal from a side feeding port, cooling and cutting to obtain the heat-conducting polypropylene material;

or (1) adding the polyethylene resin, the second polypropylene resin, the compatilizer, the foam metal and the passivator into an internal mixer, heating and mixing, and extruding and granulating by a single-screw extruder to obtain foam metal master batches; (2) mixing the first polypropylene resin and the heat-conducting filler, adding the mixture into a double-screw extruder for granulation, and cooling and cutting the mixture to obtain heat-conducting filler master batches; (3) and mixing the foam metal master batch and the heat-conducting filler master batch to obtain the heat-conducting polypropylene material which can be directly used for injection molding.

10. The use of the heat-conducting polypropylene material as claimed in any one of claims 1 to 8 in the preparation of electronic components.