High melt strength PP characteristics, application of large analysis

Sinopec: high melt strength PP characteristics, application of large analysis

 

In the past 50 years, amorphous polymers such as polyurethane (PU), polystyrene (PS), polyvinyl chloride (PVC) have been used in the field of foaming. PP is one of the five general-purpose plastics, and its dosage is second only to PE. Material engineers can not help but think: ordinary PP can not foam?

 

The answer is no.Please look down for reasons:

Wen/Zhang Shijun, Sinopec Beijing Research Institute of Chemical Industry

Why do you need high melt strength PP?

The microstructure of PP is a linear semi-crystalline structure, and the polymer with this structure lacks the tensile rheological properties to obtain a uniform and controllable cell structure during the melt foaming process. In other words, the melt viscosity of PP is not stable with the change of temperature, and the temperature difference of 5 ℃ may bring about an uncontrollable change of the melt viscosity. In addition, the melt strength of PP is small, and the foaming ratio is limited.

In the plastic foaming process, it is required that the bubbles are not broken and the foaming ratio is large; in the thermoforming process, the parison is required not to deform; in the film blowing process, the film bubble is required not to sag. PP (polypropylene) is limited in these three applications due to its low melt strength!

1. How to improve the melt strength of PP?

In this context, HMSPP (high melt strength PP) came into being. In recent years, Sinopec Zhenhai Refining and Chemical Company has cooperated with Beijing Research Institute of Chemical Industry to produce high melt strength PP with HMS20Z and E02ES, which can solve the problem that ordinary PP is difficult to foam. Let's take HMS20Z as an example to talk about the characteristics and application fields of high melt strength PP.

Compared with ordinary PP, the melt strength of HMSPP is obviously improved. How do materials engineers improve the melt strength of PP? From the molecular level, there are three main methods:

1) Increase molecular weight;

2) Widening molecular weight distribution;

3) Increase the long chain branch structure.

Comparison of Melt Strength of Homopolymeric High Melt Strength PP(HMS 20Z), Imported HMS PP and Ordinary PP

From the above chart, it can be seen that the melt strength is: Sinopec homopolymeric high melt strength PP(HMS 20Z)> imported HMS PP> ordinary PP.

Comparison of weight average molecular weight distribution of high melt strength PP(HMS 20Z) and common PP

Compared with ordinary PP, Sinopec's HMS 20Z has a wider molecular weight distribution.

2. What are the preparation methods of HMSPP (high melt viscosity PP)?

1) High-energy ray irradiation method;

2) reactive extrusion;

3) Blending method;

4) polymerization method.

Preparation Process of High Melt Strength PP of Sinopec

The above device can realize the flexible adjustment of catalyst performance between different reactors, and can produce multiple series of high-performance polypropylene products.

3. Domestic development of high melt strength PP

At present, it is mainly prepared by irradiation grafting, reactive extrusion and blending in China.

Major domestic research institutions:Beijing Institute of Chemical Industry, Institute of Chemistry, Chinese Academy of Sciences, East China University of Science and Technology, South China University of Technology, Changchun Institute of Chemical Engineering, Chinese Academy of Sciences, Qingdao University, Zhejiang University, etc.

Main Application Areas of 2. HMSPP

1.PP foam plastic

 

Preparation of Foamed Polypropylene by Extrusion

1) The advantages of HMSPP applied to foam plastics

◆ Excellent seismic energy absorption (buffer performance);

◆ Excellent heat resistance, thermal insulation and transportation at low temperature;

◆ Surface protection (semi-hard, maintaining a certain strength, toughness and plasticity, can provide better surface protection for transportation products);

◆ Good oil resistance and chemical resistance;

Recyclable and easily degradable-"green" foam.

2) Application examples

Cushioning packaging, food packaging, thermal insulation, automotive, construction, sports and leisure and industrial applications.

 

Car bumper, aibang polymer photographed in Wuxi Huitong new materials co., ltd.

2.PP thermoformed products

HMSPP thermoformed products with excellent transparency

HMSPP's thermoformed products are:

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Packaging materials: food trays, lunch boxes, cups, microwave containers, etc;

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Large containers and shells: storage tanks, bathtubs, household appliances, etc;

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Automotive supplies: car roofs, car dashboards, car brackets, seats, etc.

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Flow chart of continuous feeding equipment, 1-sheet roll; 2-heater; 3-mold; 4-trimming; 5-waste sheet material; 6-products.

3. Extruded sheet

HMSPP extruded sheet has the characteristics of light weight, uniform thickness, smooth surface, good heat resistance, high mechanical strength, excellent chemical stability and electrical insulation, non-toxic, and the use temperature can reach 100 ℃.

HMSPP Extruded Sheet

HMSPP board is widely used in chemical containers, machinery, electronics, electrical appliances, food packaging, medicine, decoration and water treatment and other fields.

4. Hollow blow molding

Hollow blow molded bottle made of HMSPP material

HMSPP has high melt strength and draw ratio. In blow molding, whether it is a film product or a large hollow product, it has a wide processing window, and the product should not be broken during the stretch blow molding process, and the shape is maintained well.

5. Blown film

PP film

HMSPP blown film has the following advantages:

1) High stiffness;

2) Good temperature resistance;

3) High gloss;

4) Excellent printing performance.

3. abroad HMSPP

Major Commercialized Brand

Lyondellbasell公司(Himont, Montell): The main brands are RS1684, ProfaxPF-611, PF-613, SD-613, etc;

Borealis companies:In 1996, the development of PP long chain branching technology, products have Daplay series products, such as WB130HMS, WB135HMS, WB140HMS, WB180HMS, WB260HMS and SF203HMS;

Honam Petrochemical:SEP-550 QSEP-740 QSEP-750;

Japan Chisso Company:Newstren series products are used for large blow molding products, Newfoamer for foaming products;

Dow Chemical:Inspire series HMS products are used for blown film, sheet, profile;

Samsung chemical company:HMS200F, HM200S, BM200, RM200X, etc;

Other companies: ExxonMobil, Rexene, Quantum Chemical, AkzoNobel, Hunts-man, etc.