CN-122008672-A - Low-density PETG heat-shrinkable label film containing microporous core layer and preparation method thereof

Abstract

The invention belongs to the technical field of heat-shrinkable label films, in particular to a low-density PETG heat-shrinkable label film containing a microporous core layer and a preparation method thereof, wherein the low-density PETG heat-shrinkable label film has a three-layer co-extrusion structure, the upper layer and the lower layer are PETG surface layers, the middle layer is a microporous core layer containing hollow glass microsphere modified PETG polymer, and the preparation method of the low-density PETG heat-shrinkable label film is provided. The invention solves the technological defect of the existing low-density PETG heat-shrinkable label film, utilizes the hollow glass beads as the low-density filler of the core layer, and cooperates with surface micropore cracks caused by the inertia of the hollow glass beads, thereby realizing the low-density of the micropore core layer and further achieving the low-density effect of the PETG heat-shrinkable label film.

Inventors

• YANG TAO
• CHEN LIYING
• ZHOU JUNFENG
• FAN QI
• ZHANG JIAYI

Assignees

• 江苏光辉包装材料有限公司

Dates

Publication Date

20260512

Application Date

20260324

Claims (10)

1. 1. A low-density PETG heat-shrinkable label film containing a microporous core layer is characterized in that the low-density PETG heat-shrinkable label film is of a three-layer co-extrusion structure, an upper layer and a lower layer are PETG surface layers, and a middle layer is a microporous core layer containing hollow glass microsphere modified PETG polymer.
2. 2. The low-density PETG heat-shrinkable label film containing a microporous core layer according to claim 1, wherein the thickness ratio of the three-layer co-extrusion structure of the low-density PETG heat-shrinkable label film is 10-15:70-80:10-15.
3. 3. The low-density PETG heat-shrinkable label film with the microporous core layer of claim 1, wherein the PETG surface layer comprises PETG resin and an open smooth master batch, and the mass ratio of the PETG resin in the PETG surface layer is 97-98%.
4. 4. The low-density PETG heat-shrinkable label film with the microporous core layer according to claim 3, wherein the PETG resin is a modified PET chip, and is specifically a CHDM modified PETG or an NPG modified PETG, wherein the CHDM modified PETG is one of Embrace (TM) copolyester, embraceTMLV copolyester, GN001, S2008 of Korean SK company and K2012 of Korean SK company, and the NPG modified PETG is one of FG718H of ceremony chemical fiber, HSF of Jiangsu Soxhlet company and W501 of Jiangyin Hua Hong.
5. 5. The low-density PETG heat-shrinkable label film containing a microporous core layer according to claim 3, wherein the open smooth masterbatch is TA10-08 MB13 of Sucarnot, switzerland or other similar products.
6. 6. The low-density PETG heat-shrinkable label film with the microporous core layer of claim 1, wherein the microporous core layer comprises a hollow glass bead modified PETG polymer and a return material, the mass ratio of the hollow glass bead modified PETG polymer is 92%, and the return material is recycled for trimming of a wire.
7. 7. The low-density PETG heat-shrinkable label film comprising a microporous core layer according to claim 1, wherein the hollow glass microsphere-modified PETG polymer is obtained by allowing hollow glass microspheres to participate in the PETG polymerization reaction and bonding the hollow glass microspheres to the PETG polymer.
8. 8. The low-density PETG heat-shrinkable label film containing a microporous core layer according to claim 1, wherein the preparation method of the low-density PETG heat-shrinkable label film comprises the following steps: Step 1, putting PETG resin and an open smooth master batch into a first extruder according to mass ratio, and plasticizing and extruding to obtain a surface layer melt raw material, wherein the plasticizing and extruding temperature of the first extruder is 255-270 ℃; Step 2, placing the hollow glass bead modified PETG polymer and the return material into a second extruder according to the mass ratio, and plasticizing and extruding to obtain a core layer melt raw material, wherein the plasticizing and extruding temperature of the second extruder is 255-270 ℃; And step 3, respectively feeding the surface layer melt raw material and the core layer melt raw material into a film preparation mechanism through pipelines, and performing processing and forming to obtain the PETG heat-shrinkable label film.
9. 9. The low-density PETG heat-shrinkable label film with a microporous core layer according to claim 8, wherein the film forming mechanism comprises a front-end distributor of a die head, a casting sheet mechanism, a transverse stretching system with a trimming mechanism, a traction system, a rolling system and a slitting system, in the film preparation mechanism, a surface layer melt raw material enters a corresponding runner of the front-end distributor of the die head through a pipeline and is divided into two material flows to form an upper surface layer and a lower surface layer, a core layer melt raw material enters a middle runner of the front-end distributor of the die head through a pipeline to form a core layer, the surface layer and the core layer form a three-layer co-extrusion structure after passing through the distributor, and the three-layer co-extrusion structure PETG sheet is formed by casting and cooling through the casting die head and the casting sheet mechanism, and the sheet is manufactured into a low-density PETG heat-shrinkable label film product with the microporous core layer through the transverse stretching system, the traction system, the rolling system and the slitting system.
10. 10. The low density PETG heat shrink label film with microporous core of claim 9, wherein the dispenser in step 3 has a temperature of 265-270 ℃, the casting die has a temperature of 265-270 ℃, the cast sheet roll of the cast sheet mechanism has a temperature of 28 ℃, the transverse stretching system has a transverse stretching multiple of 5, and the stretching temperature is 85-98 ℃.

Description

Low-density PETG heat-shrinkable label film containing microporous core layer and preparation method thereof Technical Field The invention belongs to the technical field of heat-shrinkable label films, and particularly relates to a low-density PETG heat-shrinkable label film containing a microporous core layer and a preparation method thereof. Background PETG heat-shrinkable label films are the main base film variety of shrink sleeve labels today. Because the PET bottle body and the PET bottle body are made of polyester materials and have basically consistent density, the PET bottle body and the PETG heat shrinkage label film cannot be effectively separated by a simple specific gravity difference separation method in the recycling process. Although the two materials belong to the same class of materials, the properties are obviously different, the blend extrusion melting is not possible, and the surface of the PETG label which is used as the thermal shrinkage label film is printed and is adhered with a large amount of ink. The PET waste bottles are polluted because the PETG label films cannot be separated, so that the recycling value of the PET waste bottles is reduced. Therefore, the density of the PETG heat-shrinkable label film is reduced, so that the density of the PETG heat-shrinkable label film is obviously different from that of the PET waste bottle, and the PETG heat-shrinkable label film is an important technical improvement direction in the PETG heat-shrinkable label film. The low-density PETG heat-shrinkable label film mainly adopts two techniques, namely, a low-density material such as PP, SBC and the like is used as a core layer material of the heat-shrinkable label film, or a PETG core layer is foamed. However, the core layer of the heat-shrinkable label film adopts a low-density material and is co-extruded with the PETG surface layer material to prepare the heat-shrinkable label film. Although the method can effectively reduce the density of the label film, different materials have physical property differences, so that the processing technology has larger difference, the production control difficulty is high, and the layering problem among different materials in the film is easy to occur. Meanwhile, the shrinkage of the label film can also cause a series of quality problems such as reduced overall shrinkage rate, different shrinkage effects and the like of the label film due to different shrinkage properties of different materials. The PETG heat shrinkage label film foamed by the core layer has the problems of easy bubble breaking, uneven foaming and the like in the common foaming technology due to low viscosity and poor melt strength of the PETG melt, has high actual control difficulty, and can not be industrially applied because of large shrinkage difference of the prepared film. When the carbon dioxide supercritical foaming technology is used, the core layer can obtain a relatively uniform foaming structure, but special equipment is required in the production process, a specific foaming forming device is required in the extrusion processing of the core layer material, and the strict process control condition is required. The common PETG heat-shrinkable label film production line cannot be directly processed and produced. Therefore, there is a need in the market for a low density PETG heat shrink label film that can be industrially produced and has uniform voids. Disclosure of Invention Aiming at the problems in the prior art, the invention provides the low-density PETG heat-shrinkable label film containing the microporous core layer, which solves the technical defects of the conventional low-density PETG heat-shrinkable label film, utilizes hollow glass beads as low-density filler of the core layer and cooperates with surface microporous cracks caused by the inertia of the hollow glass beads, thereby realizing the low density of the microporous core layer and further achieving the low density effect of the PETG heat-shrinkable label film. In order to achieve the technical purpose, the technical scheme of the invention is as follows: A low-density PETG heat-shrinkable label film containing a microporous core layer is of a three-layer co-extrusion structure, an upper layer and a lower layer are PETG surface layers, and a middle layer is a microporous core layer containing hollow glass microsphere modified PETG polymer. In the three-layer co-extrusion structure, the upper layer and the lower layer are both made of PETG materials and the microporous core layer is made of PETG materials, so that the surface layer and the core layer are made of the same PETG materials, have excellent identity, ensure the interlayer compatibility and connection stability of the heat-shrinkable label film, reduce interlayer cracks and interlayer differentiation, improve the surface activity in a modified mode by matching with the hollow glass beads and are bonded on the PETG materials, not only ensure the uniform