CN-121975161-A - Preparation method of high-branching degree polyolefin film

Abstract

The invention relates to a preparation method of a high-branching degree polyolefin film, which belongs to the technical field of polyolefin material processing and modification, and comprises the steps of mixing a long-branched chain or dendritic high-branching polyolefin modifier with the density of 0.86-0.92g/cm < 3 >, the MFR of 0.1-10g/10min and the branching degree of more than 30/1000 carbon, a linear polyolefin matrix and an auxiliary agent, carrying out melt shearing on the mixture in a double-screw extruder, carrying out water-cooling granulation and drying to obtain modified particles, then sending the particles into forming equipment, carrying out melt plasticization at high temperature, carrying out extrusion through a die, carrying out traction stretching, and carrying out cooling shaping, and finally obtaining the high-branching degree polyolefin film.

Inventors

• TIAN SHOUWEN

Assignees

• 天津市大阳光大新材料股份有限公司

Dates

Publication Date

20260505

Application Date

20260228

Claims (6)

1. 1. A method for preparing a high-branching polyolefin film, which is characterized by comprising the following steps: mixing a hyperbranched polyolefin modifier, linear polyolefin matrix resin and an auxiliary agent, putting into a double-screw extruder for melt blending, extruding under the shearing action, water-cooling for bracing, granulating and drying to obtain modified polyolefin particles; Adding the modified polyolefin particles into film forming equipment, melting and plasticizing at high temperature, extruding through a die, drawing, cooling and shaping to obtain a high-branching degree polyolefin film; Wherein the hyperbranched polyolefin modifier is a polyolefin with a long chain branching or dendritic structure, the density of the polyolefin is 0.86-0.92g/cm3, the melt mass flow rate (MFR, 190 ℃ C., 2.16 kg) is 0.1-10g/10min, and the branching degree is more than 30 branches per 1000 carbon atoms.
2. 2. The method for producing a highly branched polyolefin film according to claim 1, wherein the mass ratio of the highly branched polyolefin modifier to the linear polyolefin matrix resin is (5-20): (80-95).
3. 3. The method for producing a highly branched polyolefin film according to claim 1, wherein the linear polyolefin matrix resin is selected from the group consisting of linear low density polyethylene, metallocene polyethylene, polypropylene, and a combination of any one or more thereof.
4. 4. The method for preparing a highly branched polyolefin film according to claim 1, wherein the auxiliary agent comprises an antioxidant and a slipping agent.
5. 5. The method for preparing a high branching degree polyolefin film according to claim 1, wherein the processing temperature range of the twin screw extruder is 160-210 ℃ and the screw rotation speed is 200-500r/min.
6. 6. The method for producing a highly branched polyolefin film according to claim 1, wherein the film forming apparatus employs an extrusion blow molding process at a processing temperature of 170 to 200 ℃ and a blow ratio of 2.5 to 4.0.

Description

Preparation method of high-branching degree polyolefin film Technical Field The invention relates to the field of polyolefin material processing and modification, in particular to a preparation method of a high-branching degree polyolefin film. Background In the current high polymer packaging material field, linear polyolefin is widely applied to film preparation due to excellent chemical stability and mechanical property, extrusion blow molding technology is generally adopted in the production process to ensure the molding quality and processing efficiency of the final product, and strict requirements are put on the stability and rheological property of resin melt under a stretching flow field; In the prior art, although the common LDPE is added to improve the processability to a certain extent, the method generally has the problem of phase separation caused by insufficient compatibility, so that the haze of a film is obviously increased, the transparency is reduced, and the impact toughness of a material is often sacrificed; therefore, how to provide a preparation method of a high-branching degree polyolefin film capable of synergistically improving processing stability, optical performance and mechanical toughness is a problem to be solved by those skilled in the art. The above information disclosed in the above background section is only for enhancement of understanding of the background of the disclosure and therefore it may include information that does not form the prior art that is already known to those of ordinary skill in the art. Disclosure of Invention The invention aims to provide a preparation method of a high-branching degree polyolefin film, which solves the problems in the prior art. Mixing a hyperbranched polyolefin modifier, linear polyolefin matrix resin and an auxiliary agent, putting into a double-screw extruder for melt blending, extruding under the shearing action, and obtaining modified polyolefin particles after water-cooling bracing and granulating and drying; Adding the modified polyolefin particles into film forming equipment, melting and plasticizing at high temperature, extruding through a die, drawing, cooling and shaping to obtain a high-branching degree polyolefin film; Wherein the hyperbranched polyolefin modifier is a polyolefin with a long chain branching or dendritic structure, the density of the polyolefin is 0.86-0.92g/cm3, the melt mass flow rate (MFR, 190 ℃ C., 2.16 kg) is 0.1-10g/10min, and the branching degree is more than 30 branches per 1000 carbon atoms. Optionally, the mass ratio of the hyperbranched polyolefin modifier to the linear polyolefin matrix resin is (5-20): (80-95). Optionally, the linear polyolefin matrix resin is selected from any one or a combination of a plurality of linear low density polyethylene, metallocene polyethylene and polypropylene. Optionally, the auxiliary agent comprises an antioxidant and a slipping agent. Optionally, the processing temperature range of the double-screw extruder is 160-210 ℃, and the screw rotating speed is 200-500r/min. Optionally, the film forming equipment adopts an extrusion blow molding process, the processing temperature is 170-200 ℃, and the blowing ratio is 2.5-4.0. The invention provides a preparation method of a high-branching degree polyolefin film through improvement, and compared with the prior art, the preparation method has the following improvement and advantages: 1. The technical characteristics of the invention obviously improve the problems of low melt strength and poor processing rheological property of linear matrix resins such as linear low-density polyethylene, metallocene polyethylene or polypropylene and the like, thereby improving the stability of film bubble in extrusion blow molding process, preventing melt fracture or sagging phenomenon and widening the processing process window of film; 2. The preparation process ensures the microscopic uniform dispersion of the hyperbranched component in the matrix, avoids the surface defects of crystal points, fish eyes and the like caused by poor compatibility or uneven plasticization, and ensures that the finally obtained high-branching degree polyolefin film has excellent appearance quality and uniform physical property; 3. the invention strictly controls the mass ratio of the hyperbranched polyolefin modifier to the linear polyolefin matrix resin, so that the hyperbranched polyolefin modifier and the linear polyolefin matrix resin form good structural cooperation in the processes of melting plasticization and subsequent blow molding traction stretching, and the introduction of the hyperbranched structure can modify the crystallization behavior and the orientation structure of linear molecules, thereby further endowing the film finished product with more excellent toughness and stretching resistance on the basis of keeping the original characteristics of the linear resin and meeting the application requirements of the field of high-performance pa