CN1252168C - Method for modifying rheological performance of ultrahigh molecular weight polyethylene processing - Google Patents

Abstract

The invention discloses a new method for improving the processing rheological properties of ultra-high molecular weight polyethylene. By adding a small amount of hyperbranched polyester-amide polymer to ultra-high molecular weight polyethylene and kneading evenly on a torque rheometer, the processing rheological properties of ultra-high molecular weight polyethylene can be significantly improved. Can significantly reduce the melt viscosity of ultra-high molecular weight. The invention has good application prospect in the processing field of ultra-high molecular weight polyethylene.

Description

A new method to improve the processing rheological properties of UHMWPE

technical field

The invention belongs to the technical field of polyethylene composite material processing, in particular to a new method for improving the processing rheological properties of ultra-high molecular weight polyethylene.

Background technique

Hyperbranched polymers have low melt viscosity, which has great application value in modifying the rheological behavior of traditional polymers. In U.S. Patent No. 4487875, it is reported that the combination of copolymer and stearate as a lubricant for ultra-high molecular weight polyethylene (UHMW-PE) can significantly improve the processing performance of UHMWPE, so that it can be processed on a common single-screw extruder or injection machine. processing. Zhao Anchi and others reported the use of liquid crystal (LCP) to modify UHMWPE in the 6th issue of "Plastic Science and Technology" in 1997, and made a breakthrough in the field of modification of UHMWPE. The Institute of Chemistry, Chinese Academy of Sciences has developed UHMWPE modified with nano-scale layered silicate. The bonding force between their sheets is relatively weak, and the friction coefficient is very small. The relative sliding between the sheets can improve the fluidity of the UHMWPE melt, thereby improving its processing performance; and the internal structure of the sheets is tight and the rigidity is very high. , has a certain enhancement effect on the performance of UHMWPE in the two-dimensional direction. For example, when 5% hyperbranched polystyrene is added to polystyrene, the melt viscosity of the blend at 120°C can be reduced to 80% of the original.

UHMW-PE is a thermoplastic engineering plastic with excellent comprehensive properties. Because of its outstanding wear resistance (8 to 9 times that of steel), excellent impact resistance (2 times that of polycarbonate, 5 times that of ABS, and 15 times that of polyoxymethylene), low coefficient of friction (its dynamic friction The coefficient is 0.10 ~ 0.22, which is comparable to polytetrafluoroethylene, and is an ideal lubricating material), chemical resistance, low temperature resistance and sound attenuation, etc. The unique three-dimensional molecular structure of hyperbranched polymers makes it low Excellent properties such as viscosity, high reactivity and good compatibility, and many modifiable end groups make hyperbranched polymers have broad application prospects in the field of coatings. Therefore, it is entirely possible for hyperbranched polymers to replace dendritic polymers in coatings, adhesives, drug release agents, polymer catalysts, phase transfer agents, crystal nucleating agents, organic-inorganic dopant structure control agents, Development and application of functional film materials and self-assembly. Therefore, it is favored by people all over the world. Its total consumption has maintained a momentum of continuous growth. Before the 1980s, the world's average growth rate was 8.5%. After entering the 1980s, the growth rate was as high as 16%. In 1990, the world's total consumption reached 50,000 tons.

However, due to the extremely high melt viscosity of ultra-high molecular weight polyethylene during processing, as high as 108Pa s, the fluidity is extremely poor, and its melt flow index is almost zero, so it is difficult to directly extrude or inject molding. The processing method can process UHMW-PE, which is a scientific research topic that countries all over the world are competing to tackle.

Contents of the invention

The purpose of the present invention is to provide a new method for improving the processing rheological properties of ultra-high molecular weight polyethylene, which is characterized in that: ultra-high molecular weight polyethylene with a molecular weight of 1 million-3 million and a weight ratio of 1%-10% polyester - The amide hyperbranched polymer was manually stirred for 5 minutes, and mixed evenly on a Haake Rheomix 600 torque rheometer. The mixing temperature was 180-280 ° C, and the speed was 5-60 rpm. - 50 minutes, record the data of torque change with time until the change is stable.

The beneficial effect of the invention is that by adding a small amount of hyperbranched polyester-amide polymer, the processing rheological properties of ultra-high molecular weight polyethylene can be significantly improved. Can significantly reduce the melt viscosity of ultra-high molecular weight.

Detailed ways

The invention is a new method for improving the processing rheological properties of ultra-high molecular weight polyethylene. It is characterized in that: manually stir the ultra-high molecular weight polyethylene with a molecular weight of 1 million-3 million and the polyester-amide hyperbranched polymer with a weight ratio of 1%-10% for 5 minutes, and mix them on a Haake Rheomix 600 torque rheometer. The kneading is uniform, the kneading temperature is 180-280°C, and the rotation speed is 5-60 rpm, kneading for 5-50 minutes, and the data of torque changing with time is recorded until the change is stable.

Example:

1. 50 parts of ultra-high molecular weight polyethylene with a molecular weight of 2 million, and 1 part of polyester-amide hyperbranched polymer, mixed uniformly at room temperature, and mixed on a Haake Rheomix 600 torque rheometer at a speed of 30 rpm 15-30 minutes, record data until the change is stable

2. The number of polyester-amide hyperbranched polymers is changed to 2 parts, and the others are the same as above.

3. The number of polyester-amide hyperbranched polymer parts is changed to 3 parts, and the others are the same as above.

4. The number of polyester-amide hyperbranched polymer parts is changed to 5 parts, and the others are the same as above.

5. In embodiment 1, the molecular weight of UHMWPE is changed to 3 million, and the number of polyester-amide hyperbranched polymers is changed to 3 parts, and others are the same as above

6. In embodiment 1, the molecular weight of ultra-high polyethylene is changed into 3 million, and the number of polyester-amide hyperbranched polymer parts is changed into 5 parts, and other is the same as above.

Comparative example:

1. In embodiment 1, adopt molecular weight to be 2,000,000 ultra-high molecular weight polyethylenes, directly record its melting torque with HaakeRheomix 600 torque rheometer, other are identical.

2. In embodiment 1, adopt molecular weight to be 3,000,000 ultra-high molecular weight polyethylene, directly record its melting torque with HaakeRheomix 600 torque rheometer, other are identical.

The torque values measured by the Haake Rheomix 600 torque rheometer in the above examples are shown in the table below.

Effect of PF ₂ on rheological torque of ultra-high molecular weight polyethylene Example PF ₂ addition amount (wt%) Mixed melt torque (N m) Torque value reduction degree (%) Comparative Example 1 Embodiment 1 Embodiment 2 Embodiment 3 Embodiment 4 Comparative Example 2 Embodiment 5 Embodiment 6 01235035 40282464534825 0304085900953

Comparative examples can be found that the melting torque measured by Haake Rheomix600 torque rheometer by modified ultra-high molecular weight polyethylene all reduces to some extent, when the content of this hyperbranched polymer added is at 3%, it can be The melting torque of the purified ultra-high molecular weight polyethylene is reduced by 85% (2 million grades) and 53% (3 million grades), and the modification effect is obvious.

Claims (1)

1.-plant the novel method of improving the ultrahigh molecular weight polyethylene(UHMWPE) processing rheological property, it is characterized in that: with molecular weight is that 1,000,000-3,000,000 ultrahigh molecular weight polyethylene(UHMWPE) and weight ratio 1%-10% polyester-amides hyperbranched polymer manually stirred 5 minutes, mixing even on Haake Rheomix 600 torque rheometers, melting temperature is 180-280 ℃, rotating speed is under 5-60 rev/min the condition, mixing 5-50 minute, the record moment of torsion in time delta data to vary stable.