Search

CN-121405994-B - PVC transparent film for migration-free toy and preparation method thereof

CN121405994BCN 121405994 BCN121405994 BCN 121405994BCN-121405994-B

Abstract

The invention relates to the technical field of high polymer materials, in particular to a PVC transparent film for a migration-free toy and a preparation method thereof. The invention discloses a PVC transparent film for a migration-free toy and a preparation method thereof, wherein the preparation method comprises the steps of constructing a liquid-solid phase double-blocking system, namely forming a liquid-phase chelating blocking layer in a premixing stage, introducing nano-coating filler to construct a solid-phase blocking network, and cooperatively blocking heavy metal and micromolecule migration; meanwhile, a calendaring-quenching optical shaping process is adopted, crystallization is restrained through high-temperature calendaring and rapid cooling of a mirror roller, and high transparency of the film is guaranteed. The PVC transparent film prepared by the invention has the excellent characteristics of zero heavy metal migration, high transparency and high toughness.

Inventors

  • LIU JIANWEI
  • HE BINGQIANG
  • LIU ZHIDAN
  • KUANG LIHUA

Assignees

  • 广东裕泰实业集团有限公司

Dates

Publication Date
20260508
Application Date
20251224

Claims (10)

  1. 1. A preparation method of a PVC transparent film for a migration-free toy comprises mixing and calendaring, and is characterized in that the mixing is formed by sequentially mixing different raw materials according to different stages, the different stages are formed by interface modification, vacuum homogenization plasticizing and composite reinforcement according to time sequences, the interface modification is formed by premixing a stabilizer and a lubricant with PVC resin raw materials to form a liquid phase blocking layer for wrapping the PVC resin raw materials, the vacuum homogenization plasticizing is formed by adding a plasticizer in a vacuum environment to realize permeation and adhesion of the plasticizer, the composite reinforcement is formed by filling and mixing silica coated calcium carbonate nano particles to enable the silica coated calcium carbonate nano particles to be uniformly dispersed and embedded into a PVC matrix to form a solid phase network, the calendaring is formed by three-roller high-temperature casting sections and independent mirror cooling sections, the temperature of the mirror cooling sections is smaller than the roller temperature of the calendaring sections, the difference is larger than 100 ℃, the three-roller high-temperature casting sections and the independent mirror cooling sections are cooperated to realize time sequence control on PVC microcosmic forms, the liquid phase blocking layer and the solid phase blocking layer are completely mixed with the solid phase carbon dioxide coated calcium carbonate nano particles in a vacuum environment, the vacuum phase blocking method is completed by completely sealing the liquid phase blocking layer with the vacuum carbon dioxide coated calcium carbonate nano particles, and the vacuum protection film is completely filled with the pure calcium carbonate vacuum-phase carbon dioxide, and the vacuum protection film is completely sealed after the vacuum sealing is completely filled with the solid phase carbon dioxide film, and the vacuum-coated calcium carbonate is completely mixed, and the vacuum-coated with the vacuum carbon dioxide film is completely and completely sealed, and the vacuum-phase-coated with the vacuum film is completely coated.
  2. 2. The method for preparing the PVC transparent film for the migration-free toy according to claim 1, wherein the plasticizer comprises a compound system of phthalate plasticizers and environment-friendly plasticizers, the phthalate plasticizers are dioctyl phthalate and diisononyl phthalate, the environment-friendly plasticizers are dioctyl terephthalate, the mirror cooling section is that a film blank formed by calendaring is immediately led into a mirror cooling roller which is independently arranged, the surface temperature of the mirror cooling roller is 10-20 ℃, the film blank is subjected to contact cooling on the surface of the mirror cooling roller for 5-15 seconds, and the temperature is reduced to below 50 ℃, so that shaping is achieved.
  3. 3. The preparation method of the PVC transparent film for the migration-free toy according to claim 1, wherein the high-purity liquid calcium-zinc stabilizer is a calcium-zinc organic salt liquid stabilizer without any toxic heavy metal impurities, and the premixing is performed under the protection of cold water under the condition of 45-60 ℃ for 2-5 minutes.
  4. 4. The method for preparing the PVC transparent film for the migration-free toy according to claim 1, wherein the plasticizer is pumped in, dioctyl phthalate, diisononyl phthalate and dioctyl terephthalate are pumped in sequence, the temperature is raised and vacuumized, the temperature is raised to 75-85 ℃ and vacuumized for 3-8 minutes, and the vacuum is maintained at a vacuum degree of-0.095 to-0.08 MPa.
  5. 5. The method for preparing the PVC transparent film for the migration-free toy according to claim 1, wherein the functional auxiliary agents are respectively a flame retardant, a mildew inhibitor, an antistatic agent and an ultraviolet inhibitor, the functional auxiliary agents are required to be added first, then the high-purity silicon dioxide coated calcium carbonate is added, the adding sequence is not reversible, the high-purity silicon dioxide coated calcium carbonate has a shell thickness of 10nm, the coating rate is more than 95%, lead is less than or equal to 0.5ppm, and the whiteness delta L+2.
  6. 6. The method for preparing the PVC transparent film for the migration-free toy according to claim 1, wherein the step of preparing the liquid phase blocking layer and the solid phase blocking network is that after solid phase particles are dispersed, dry mixed materials are sent into a rolling line to be pressed into a film, and then are quenched by a mirror cooling roller to be rolled below 50 ℃ to finish shaping, and then are sent to a laboratory to measure the content of heavy metals and phthalate esters, so that the preparation of the zero metal migration film is realized.
  7. 7. The method for producing a PVC transparent film for a migration-free toy according to claim 6, wherein the linear velocity of the pressed film is 15 to 30m/min, and the condition for quenching by a mirror-surface cooling roller is set to be 10 to 20 ℃ for 8 to 15 seconds.
  8. 8. The PVC transparent film for the migration-free toy, which is prepared by the preparation method of any one of claims 1-7, is characterized by comprising the following components, by mass, 100 parts of PVC resin, 23-65 parts of plasticizer, 0.2-0.5 part of oxidized polyethylene wax, 1.5-3.0 parts of high-purity liquid calcium zinc stabilizer, 0.2-0.5 part of phosphite ester, 5-15 parts of silicon dioxide coated calcium carbonate and 3.8-10.8 parts of functional auxiliary agent.
  9. 9. The PVC transparent film for a migration-free toy according to claim 8, wherein the plasticizer comprises 15-30 parts of dioctyl phthalate, 5-15 parts of diisononyl phthalate and 3-20 parts of dioctyl terephthalate, and the functional auxiliary agent comprises 3.8-10.8 parts of a flame retardant, 0.3-1.0 part of a mildew preventive, 0.2-0.8 part of an antistatic agent and 0.3-1.0 part of an ultraviolet resistant agent.
  10. 10. The PVC transparent film for a migration-free type toy according to claim 8, wherein the haze of the transparent film is not more than 1.3%, the light transmittance is not less than 91.0%, the tensile strength is not less than 25.8MPa, and the elongation at break is not less than 285%.

Description

PVC transparent film for migration-free toy and preparation method thereof Technical Field The invention relates to the technical field of high polymer materials, in particular to a PVC transparent film for a migration-free toy and a preparation method thereof. Background Polyvinyl chloride (PVC) is widely used for manufacturing various transparent films due to its excellent processability and transparency. However, the conventional PVC transparent film has long faced the dilemma of double migration, on one hand, the conventional barium-zinc powder stabilizer and mineral sources with heavy metals cannot meet the increasingly strict requirements of electronics, food and medical packaging on zero risk dissolution, and on the other hand, the low-molecular plasticizer diffuses to the surface under heat, solvent or pressure to cause whitening and haze increase, and meanwhile, the multi-layer heterogeneous material blocking scheme also blocks the recycling path. Recently, some studies have explored the problem of double migration of PVC transparent films. The method is characterized in that a smooth surface of a PVC film is isolated by a PET film, molecular migration extinction caused by contact of the smooth surface is effectively inhibited, meanwhile, an optical-grade PET film is arranged on a molding surface of the PVC film in an on-line laminating mode, a secondary calendaring and brightening coating process of a mirror roller is eliminated, calendaring-laminating-rolling integrated production is realized, CN120329613A discloses a novel PVC functional auxiliary agent for inhibiting release of toxic plasticizers, a preparation method and application thereof, and the PVC functional auxiliary agent based on a layered double hydroxide structure is obtained through the steps of coprecipitation, crystallization, drying and the like of a precursor solution and a modifier solution, and effectively inhibits migration of PVC harmful substances through the spatial resistance action of surface adsorption and nano particles, so that the volatility and migration resistance of the PVC film are obviously improved, and the potential threat of PVC products to the environment and human health is reduced. However, the prior art either focuses on plasticizer migration or simply replaces non-toxic fillers, but fails to address heavy metal blockage and optical-mechanical-recovery simultaneously in the same production line. In summary, how to innovate a preparation method, not only can ensure that the migration amount of heavy metal elements approaches zero, but also can effectively inhibit the migration of plasticizers, prevent the film from whitening, and ensure that the film has high transparency and good mechanical strength, so that the technical problem to be solved in the field is urgent. Disclosure of Invention The invention aims to overcome the defects of the prior art, and provides a PVC transparent film for a migration-free toy and a preparation method thereof, so as to solve the technical problems of over-limit heavy metal dissolution, plasticizer migration and whitening, optical-mechanical conflict and the like in the prior art. The specific technical scheme is as follows: The preparation method comprises the steps of carrying out interface modification on a PVC matrix by constructing a liquid-solid phase double-blocking network, carrying out vacuum homogenization plasticization by adopting an innovative calendaring-quenching optical shaping process on the basis, and finally carrying out composite reinforcement by filling and mixing silica coated calcium carbonate nano particles, thereby successfully preparing the PVC transparent film for the zero metal migration toy, which has extremely safety, high transparency and excellent mechanical property. Further, the liquid-solid phase double blocking refers to that the liquid blocking layer and the solid phase blocking network are chemically bonded and physically interwoven through an interface to form a multiple protection system from a molecular level to a nanometer scale, wherein the liquid phase layer realizes molecular anchoring and initial stabilization, the solid phase network provides physical blocking and long-acting durability, and the liquid phase blocking layer and the solid phase blocking network are coupled in time sequence and complementary in space, so that blocking of small molecular plasticizers and heavy metal ions is jointly realized. Further, the liquid-phase blocking layer is a chelate protection layer formed by using a high-purity liquid calcium-zinc stabilizer to preferentially spread on the surface of PVC resin particles in a low-temperature premixing stage, and the protection layer realizes initial thermal stabilization through coordination between calcium-zinc (Ca-Zn) metal ions and active chlorine atoms on PVC molecular chains, and simultaneously changes the polarity of the resin surface to construct an interface bridge for efficient infiltration of