WO2021135599A1

WO2021135599A1 - Polyethylene composition and preparation method therefor

Info

Publication number: WO2021135599A1
Application number: PCT/CN2020/125122
Authority: WO
Inventors: 李振华; 黄险波; 叶南飚; 王琪; 杨波; 俞飞; 李伟; 吴国峰; 罗忠富
Original assignee: 金发科技股份有限公司
Priority date: 2019-12-30
Filing date: 2020-10-30
Publication date: 2021-07-08
Also published as: CN111117036A; CN111117036B

Abstract

Disclosed is a polyethylene composition, comprising the following components in parts by weight: 100 parts of a polyethylene resin, 0-34 parts of a filler and 0.05-2.5 parts of a foaming agent; the polyethylene resin is a low-density polyethylene resin, and at 230°C and a load of 2.16 kg, the melt mass flow rate of the polyethylene resin is 10-30 g/10 min. In the present invention, by means of optimizing polyethylene materials having different fluidities, the described polyethylene composition is obtained as a micro-foaming material. A "sandwich" skin-core structure provided with a dense skin layer on the outside can be formed, and the structure has fine and dense pores. The present invention can achieve a weight loss of about 25%, has good sound insulation and good formability, and has good prospects in applications such as automobile air duct and wheel cover sound insulation materials and front wall sound insulation materials. Further provided is a method for preparing a polyethylene composition.

Description

Polyethylene composition and preparation method thereof

Technical field

The invention relates to the technical field of polymer materials, in particular to a polyethylene composition and a preparation method thereof.

Background technique

As a cost-effective general-purpose plastic, polyethylene has high strength, high toughness, excellent mechanical properties, chemical resistance, low water absorption, and excellent electrical insulation after modification. It is widely used in automotive interior and exterior products.

Patent CN 109263214 A discloses a soundproof composite material for the front wall of an automobile, which includes a sound-absorbing cotton layer in the middle layer and a first layer of polymer sheet and a second layer of polymer sheet on both sides of the sound-absorbing cotton layer. A raised obstacle is set between one layer of polymer sheet and the second layer of polymer sheet on the side close to the sound-absorbing cotton, so that the sound wave is refracted and the direction of the sound wave is greatly changed so that the sound-absorbing cotton can effectively absorb sound waves. The above methods are mainly from the structural design. Instead of starting from the structure of the material itself, there is significant room for improvement in the sound insulation improvement effect. In addition, CN 109627550 A discloses a foaming material added with AC foaming agent to obtain a dense and high closed cell foaming material. On the one hand, the added AC foaming agent itself will be released during the foaming process. Ammonia and the residues after foaming also have carcinogenic risks. Therefore, the use of such foaming agents is difficult to be used in a wide range of home appliances and automotive products. At the same time, the foamed PE material shown in this patent is added with a certain amount The EPDM and glass fiber make the material molding performance decrease, which limits its use in some complex structural parts.

At present, most PE automotive interior and exterior sound insulation materials on the market are composed of polymer materials and sound insulation cotton to form a multilayer composite sound insulation material. The material preparation process is relatively complicated, and the material cost is high. Based on the lightweight requirements of the automotive industry, each component has Clear lightweight indicators.

Therefore, there is still a need to develop an automotive interior and exterior trim that is simple to prepare and can be effectively applied to automotive parts with complex structures, which not only meets the automotive requirements for lightweight materials, but also has better sound insulation performance.

Summary of the invention

The purpose of the present invention is to overcome the shortcomings of the prior art and provide a polyethylene composition and a preparation method thereof.

In order to achieve the above objective, the technical solution adopted by the present invention is: a polyethylene composition comprising the following components in parts by weight: 100 parts of polyethylene resin, 0 to 34 parts of filler and 0.05 to 2.5 parts of foaming agent; The polyethylene resin is a low-density polyethylene resin, and the melt mass flow rate of the polyethylene resin is 10-30 g/10 min at 230° C. and a load of 2.16 kg.

By optimizing polyethylene materials with different fluidities, the polyethylene composition is obtained as a micro-foam material, which can form a "sandwich" skin-core structure with a dense skin layer on the outside, with fine cells, which can achieve about 10% The weight reduction, good sound insulation, and good formability at the same time, it has a good prospect in the application of automobile air duct, wheel cover sound insulation material, front wall sound insulation material and so on.

Preferably, the filler is calcium carbonate and/or talc. The particle size D50 of the filler is less than or equal to 5 μm.

Preferably, the filler is 10-30 parts. The addition of fillers plays the role of foaming and nucleation when the material is foamed, increasing the number of foaming nuclei and increasing the number of cells, which can increase the cell density of the material, while reducing the cell size and improving foaming The sound insulation performance of the material, but excessive addition of talc powder will further increase the viscosity of the material, which will make the expandability of the material worse, resulting in a decrease in cell density. When the talc powder is added in the above amount, it can have a better sound insulation effect. More preferably, the filler is 24 parts. When the amount of talcum powder added is 24 parts, the sound insulation effect is the best.

Preferably, the foaming agent is at least one of bicarbonate and citrate.

Preferably, the polyethylene composition further contains 0-2 parts of auxiliary agents and 0-2 parts of pigments.

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

Preferably, the antioxidants are hindered phenol and phosphite antioxidants.

Preferably, the light stabilizer is a hindered amine light stabilizer.

Preferably, the lubricant is at least one of silicones, esters, amides, polyethylenes, stearic acids, fatty acids and esters.

The present invention also provides a method for preparing the above-mentioned polyethylene composition, which includes the following steps: mix the components except the foaming agent uniformly and then add them to the twin-screw extruder, perform melt mixing, and melt mixing temperature The temperature is 170-220°C, the screw speed is 350-450 rpm, extrusion granulation, then adding foaming agent, injection molding into the mold, to obtain the polyethylene composition.

After the foaming agent is added, the invention adopts a secondary mold opening process for injection molding. The part close to the mold during injection molding forms a dense skin layer due to pre-cooling, and the material that has not been completely cooled inside is further foamed when the mold is slightly opened for the first time. Therefore, a "sandwich" skin-core structure with a dense skin layer on the outside can be formed, which has weight reduction and sound insulation properties.

The beneficial effects of the present invention are: the present invention provides a polyethylene composition. The polyethylene composition of the present invention optimizes polyethylene materials with different fluidity to obtain the polyethylene composition as a kind of micro-foaming material, which can form a "sandwich" skin-core structure with a dense skin layer on the outside, and has cells It is compact, can achieve a weight reduction of about 25%, has good sound insulation, and has good formability. It has a good prospect in applications such as automobile air ducts, wheel cover sound insulation materials, and front wall sound insulation materials.

Detailed ways

In order to better illustrate the objectives, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

In the examples and comparative examples, all the raw materials were purchased from the market. Among them, the polyethylene resins were all low-density polyethylene resins, and the melt mass flow rate at 230° C. under a load of 2.16 kg is shown in Table 1.

Table 1 Melt mass flow rate of polyethylene resin

To	聚乙烯1Polyethylene 1	聚乙烯2Polyethylene 2	聚乙烯3Polyethylene 3	聚乙烯4Polyethylene 4	聚乙烯5Polyethylene 5
MFR(g/10min)MFR(g/10min)	1010	2020	3030	55	3535

The particle size of talc powder is D50=5μm.

The foaming agent is a bicarbonate foaming agent, purchased from EE25C of Yonghe Chemical Industry Co., Ltd.;

The pigment is black masterbatch, purchased from Cabot Company, the model is UN2005;

The antioxidants were purchased from Shandong Sanfeng Group Co., Ltd., and the models were 1010 (hindered phenolic antioxidants) and 168 (phosphite antioxidants); the weight ratio of 1010 to 168 was 1:1;

The light stabilizer is a hindered amine light stabilizer, purchased from Beijing Tiangang Auxiliary Co., Ltd., model 3808.

The formulas of the polyethylene compositions described in Examples 1-13 and Comparative Examples 1-6 are shown in Table 2 and Table 3.

The polyethylene resin, talc, pigment, antioxidant, and light stabilizer in the formulations of Comparative Example 4 and Comparative Example 6 were mixed uniformly and then added to the twin-screw extruder for melting and mixing. The melting and mixing temperature was 170-220. ℃, the screw speed is 350-450 rpm, extrusion granulation, process injection molding into 100mm*100mm*1.5mm sample pieces, to obtain the polyethylene composition sample pieces of Comparative Example 4 and Comparative Example 6.

The polyethylene resin, talcum powder, pigment, antioxidant, and light stabilizer in the formulations of Comparative Examples 1-13, Comparative Examples 1-3 and Comparative Example 5 were mixed uniformly and then added to a twin-screw extruder for melt mixing. Melt mixing temperature is 170～220℃, screw speed is 350～450 rpm, extrude and granulate, then add foaming agent, and use secondary moulding process to inject into 100mm*100mm*2.5mm sample, get comparative example 1-13. The polyethylene composition samples of Comparative Examples 1 to 3 and Comparative Example 5.

To test the properties of the polyethylene composition samples described in Examples 1-13 and Comparative Examples 1-6, the test methods are as follows:

Cell density: Take a cross-sectional scanning electron microscope photo of the sample, and calculate the cell density in a certain volume according to the cell size and cell distribution in the cross-sectional photo.

Sound insulation effect at different frequencies: the sound insulation test impedance tube is used to test the sound insulation effect of the material. Sound waves of different frequencies are emitted at one end of the impedance tube. A disc with a sample size of 100mm diameter is inserted in the middle of the impedance tube, and the sample is close to the sound source. Sound sensors are installed on both sides of the sound source and away from the sound source to test the intensity of the sound in dB. The difference between the two is the sound insulation value of the sample.

Table 2 Formulations (parts by weight) and performance test results of the polyethylene compositions of Examples 1 to 8 and Comparative Examples 1 to 4

Table 3 Formulations (parts by weight) and performance test results of the polyethylene compositions of Examples 9-13 and Comparative Examples 5-6

"-" in the table means no addition.

Generally speaking, the higher the cell density and the smaller the cell size, the better the sound insulation effect. The sound intensity at 500Hz is greater than 23.5dB, the sound intensity at 1000Hz is greater than 23.8dB, the sound intensity at 1500Hz is greater than 36.2dB, and at 2000Hz. The sound intensity is greater than 19.5dB, which can achieve better sound insulation and noise reduction effects than foam, and greatly reduce production costs.

It can be seen from the test results in Table 2 and Table 3 that the addition of foaming agent can increase the cell density of the polyethylene material and improve the sound insulation effect; low-density polyethylene resins with different melt mass flow rates have a significant effect on the degree of foaming. The greater the impact, when the MFR is less than 10g/10min, the cell density is small, and the sound insulation effect is not improved. With the increase of MFR, the cell density increases and the sound insulation effect increases. When the MFR is greater than 30g/10min, the foam Pore quality is reduced, there are many large pores, the formability of the material is poor, the cells are easily broken, the surface of the polypropylene material has serious quality problems, the appearance is deteriorated, and the sound insulation effect is reduced. The addition of fillers can increase the sound insulation effect. With the increase of filler content, the sound insulation effect increases. However, when the amount of talc powder is more than 30 parts, the sound insulation effect is reduced. When the amount of talc powder is more than 34 parts, the sound insulation effect is not improved. Obvious, and the appearance deteriorates.

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 has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that, The technical solution of the present invention may be modified or equivalently replaced without departing from the essence and scope of the technical solution of the present invention.

Claims

A polyethylene composition, characterized in that it comprises the following components in parts by weight: 100 parts of polyethylene resin, 0-34 parts of fillers and 0.05-2.5 parts of foaming agent; said polyethylene resin is a low-density polyethylene resin , At 230° C. and a load of 2.16 kg, the melt mass flow rate of the polyethylene resin is 10-30 g/10 min.
The polyethylene composition of claim 1, wherein the filler is calcium carbonate and/or talc.
The polyethylene composition of claim 1, wherein the filler is 10-30 parts; preferably, the filler is 24 parts.
The polyethylene composition of claim 1, wherein the foaming agent is at least one of bicarbonate and citrate.
8. The polyethylene composition of claim 1, wherein the polyethylene composition further comprises 0 to 2 parts of additives and 0 to 2 parts of pigments.
The polyethylene composition of claim 5, wherein the auxiliary agent is at least one of an antioxidant, a light stabilizer, and a lubricant.
The polyethylene composition of claim 1, wherein the antioxidant is hindered phenol and phosphite antioxidants.
The polyethylene composition of claim 1, wherein the light stabilizer is a hindered amine light stabilizer.
8. The polyethylene composition of claim 6, wherein the lubricant is at least one of silicones, esters, amides, polyethylenes, stearic acids, fatty acids, and esters.
The method for preparing a polyethylene composition according to any one of claims 1 to 9, characterized in that it comprises the following steps:

The components except for the foaming agent are mixed uniformly and then added to the twin-screw extruder for melt mixing. The melting and mixing temperature is 170-220℃, the screw speed is 350-450 rpm, and the extrusion granulation is carried out. , And then add a foaming agent, and injection into the mold to obtain the polyethylene composition.