Search

CN-121991382-A - Nucleating agent master batch and preparation method and application thereof

CN121991382ACN 121991382 ACN121991382 ACN 121991382ACN-121991382-A

Abstract

The invention relates to a nucleating agent master batch and a preparation method and application thereof. The preparation method comprises a mechanical activation process, an ultrathin film coating process and a pre-dispersion process of blending with a polymer, and can effectively avoid the physical agglomeration problem of the nucleating agent, so that the nucleating agent is efficiently dispersed in the resin. The invention also provides a method for preparing the special low-haze LLDPE film material by using the nucleating agent master batch, which comprises the following components, by mass, 90-95 parts of LLDPE resin, 0.05-0.15 part of antioxidant, 0.01-0.05 part of antistatic agent, 0.01-0.05 part of acid absorber, 0.1-0.5 part of processing aid and 1-8 parts of nucleating agent master batch, wherein the film prepared by using the special material has the characteristic of low haze.

Inventors

  • ZHANG ZHENJIE
  • GU YANG
  • MA XIAOHAN
  • LI SHENGLONG
  • QI WANGSHUN
  • TIAN YU

Assignees

  • 万华化学集团股份有限公司

Dates

Publication Date
20260508
Application Date
20241104

Claims (10)

  1. 1. A method for preparing a nucleating agent masterbatch, comprising the steps of: 1) Mechanically grinding and activating the nucleating agent to prepare nucleating agent powder; 2) Preparing a uniform dispersion liquid of polyvinyl alcohol and a good solvent; 3) Adding a nucleating agent powder into the dispersion liquid in the step 2) to obtain a nucleating agent microemulsion; 4) Standing the nucleating agent microemulsion of the step 3), and obtaining nucleating agent powder with the surface coated with the polyvinyl alcohol ultrathin film after the solvent in the microemulsion is completely volatilized; 5) And (3) melting and blending the nucleating agent powder coated with the polyvinyl alcohol ultrathin film in the step (4) with POE and polyethylene wax to obtain the nucleating agent master batch.
  2. 2. The method of manufacturing according to claim 1, characterized in that: The nucleating agent in the step 1) is a carboxylate nucleating agent, preferably a benzoate nucleating agent, more preferably a hexahydrophthalate metal salt nucleating agent, and the mechanical grinding activation is preferably carried out by adopting a ball mill, wherein the ball milling rotating speed is 300-450r/min, and the ball milling time is 1-3h.
  3. 3. The method of manufacturing according to claim 1, characterized in that: The polymerization degree of the polyvinyl alcohol in the step 2) is 300-1700, preferably 300-500, the alcoholysis degree of the polyvinyl alcohol is 78-99%, more preferably 78-88%, the good solvent is one or more of water, DMF and DMSO, the concentration of the dispersion is 2-8wt%, the heating temperature is 90-100 ℃ and the stirring speed is 200-300r/min during the preparation process.
  4. 4. The method of manufacturing according to claim 1, characterized in that: The nucleating agent content in the nucleating agent microemulsion of the step 3) is 20-40wt%, preferably 20-30wt%, and the nucleating agent powder is added in the step 3) preferably while stirring, wherein the stirring speed is 200-1000r/min, preferably 400-600r/min.
  5. 5. The method of manufacturing according to claim 1, characterized in that: The POE melt flow rate in the step 5) is 1-2g/10min,2.16kg, under the test condition of 190 ℃, the density is preferably 0.890-0.910g/cm 3 , and the weight average molecular weight of the polyethylene wax is preferably 500-5000g/mol.
  6. 6. The method of claim 1 or 5, wherein: The mass ratio of POE to polyethylene wax in the step 5) is 2-9:1, preferably, the concentration of the prepared nucleating agent master batch is 1-5wt%, more preferably 1-2wt%, and the heating melting temperature is preferably 170-200 ℃.
  7. 7. A low haze LLDPE film special material is characterized by comprising the following components: 90-95 parts of LLDPE resin; 0.05-0.15 part of antioxidant; 0.01-0.05 part of antistatic agent; 0.01-0.05 part of acid absorber; 0.1-0.5 part of processing aid; 1-8 parts of nucleating agent master batch.
  8. 8. The low haze LLDPE film special material according to claim 7, wherein the LLDPE resin has a density of 0.915-0.925g/cm 3 , preferably the LLDPE resin has a melt flow rate of 0.5-5.0g/10min, under 190 ℃ test conditions, the antioxidant is preferably one or more of 1076, 1010, 168 and 3114, the antistatic agent is preferably one or more of fatty acid ester, ethoxylated amine and fatty amine polyoxyethylene ether, the acid absorber is preferably one or more of zinc stearate and calcium stearate, and the processing aid is preferably one or more of vinylidene fluoride/tetrafluoroethylene/hexafluoropropylene copolymer, polysiloxane and silicone.
  9. 9. The preparation method of the low-haze LLDPE film special material is characterized by comprising the following steps of: S1, uniformly mixing LLDPE resin, an antioxidant, an antistatic agent, an acid absorber, a processing aid and a nucleating agent master batch prepared by the preparation method according to any one of claims 1 to 6 to obtain a primary mixture; S2, transferring the primary mixture prepared in the step S1 into a double-screw extruder, extruding and granulating, cooling, granulating and drying to obtain a LLDPE film special material with low haze; Preferably, the heating melting temperature in the double-screw extruder is 180-230 ℃, the extrusion temperature is 190-220 ℃, and the screw rotating speed is 200-350r/min.
  10. 10. The application of the LLDPE film special material prepared by the preparation method according to claim 9 in the fields of packaging films and agricultural films.

Description

Nucleating agent master batch and preparation method and application thereof Technical Field The invention relates to the field of polyethylene, in particular to a nucleating agent master batch, a preparation method thereof and application thereof in the field of LLDPE films. Background LLDPE film has higher tensile strength, good tear resistance and puncture resistance, and relatively lower production cost, but because LLDPE main chain is of a linear structure, branched chains on a molecular chain are shorter, the arrangement among molecules is more regular, a large number of crystals and supermolecular structures are formed in the film blowing processing process, and the crystal structure has larger size, so that the haze of the film is larger, and the popularization and application of the film are limited. At present, products of major LLDPE film manufacturers at home and abroad have the defect of higher haze except LLDPE produced by using metallocene or other transition metal catalysts. The film is an important application form of LLDPE, and the control of haze is of great significance for film application. Film haze can be classified into surface haze and internal haze according to the cause of generation, and is determined by the surface structure and internal structure of the film, respectively. On one hand, the roughness of the surface structure has a larger influence on the haze, LLDPE resin can generate periodical melt fracture in the process of plasticizing and extruding a screw rod, the surface is in a 'shark skin' phenomenon to form a rough surface, a proper amount of fluoropolymer processing aid can be permeated into the resin at present, and the LLDPE resin has higher polarity and is completely incompatible with LLDPE melt, but has high affinity with the metal surface, so that the LLDPE resin can migrate to a runner and the inner wall of a die through the melt to form a lubricating layer, the melt fracture phenomenon is effectively eliminated, and the like, a proper amount of polysiloxane or silicone powder is doped into the resin, so that the processing fluidity of the LLDPE resin can be effectively improved, the roughness is reduced, and the haze of a film product is reduced. On the other hand, the spherulitic size of the internal structure has larger influence on the haze, and the nucleating agent with excellent nucleating effect can be introduced to replace the crystallization nucleus of LLDPE at present, so that the crystallization process directly enters the crystallization growth stage based on the nucleating agent, the crystallization rate during forming is greatly improved, the crystallization size is thinned, and the haze is reduced. In view of the problem that the nucleating agent is liable to agglomerate, in order to ensure that the number of heterogeneous nucleation sites of the nucleating agent is sufficient to refine the grain size, a larger amount of addition is generally required, but if a very efficient dispersion of the nucleating agent inside the resin can be achieved, a good haze reducing effect can be achieved with a smaller amount. Disclosure of Invention In order to meet the demands of special resin for low-haze film materials, the invention provides a method for ultrafine dispersion of a nucleating agent, which comprises a mechanical activation process, an ultrathin film coating process and a pre-dispersion process of blending with high-melt-index polymers, wherein the prepared nucleating agent master batch is used for preparing LLDPE films, so that the problem of physical aggregation of the nucleating agent can be effectively avoided. In order to achieve the above purpose, the invention is realized by the following technical scheme: in a first aspect, the invention provides a method for preparing a nucleating agent masterbatch, comprising the steps of: 1) Mechanically grinding and activating the nucleating agent in a ball mill to prepare nucleating agent powder; 2) Preparing a good solvent solution of polyvinyl alcohol; 3) Adding nucleating agent powder into the dispersion liquid in the step 2) under the stirring condition to obtain nucleating agent microemulsion; 4) Placing the nucleating agent microemulsion of the step 3) at room temperature for 48-72h to enable the solvent in the microemulsion to volatilize completely, and obtaining nucleating agent powder with the surface coated with the polyvinyl alcohol ultrathin film; 5) And (3) heating, melting and blending the nucleating agent powder coated with the polyvinyl alcohol ultrathin film on the surface of the step (4), POE and polyethylene wax to obtain the nucleating agent master batch. In the invention, the nucleating agent in the step 1) is a carboxylate nucleating agent, preferably a benzoate nucleating agent, more preferably a hexahydrophthalic acid metal salt nucleating agent, wherein the ball milling speed is 300-450r/min, and the ball milling time is 1-3h; In the invention, the polymerization degree of the