Environmentally friendly degradable heat-shrinkable film formed by tape casting and manufacturing method thereof

Abstract

The invention relates to the field of processing and manufacturing of heat-shrink films, and in particular relates to a tape-casting environment-friendly degradable heat-shrink film and a manufacturing method thereof. The environment-friendly degradable heat-shrink film is of a three-layer (B / A / B) structure, wherein A is a base material core layer, and B is a printable surface layer; each printable surface layer comprises degradable poly lactic acid (PLA) resin, nano-silicon dioxide and processing aids. Materials of the base material core layer and the printable surface layers are put into a mold head through a double-screw exhaust type extruder, a coarse filter, a metering pump, a fine filter and a static mixer respectively, converge at the mold head and are extruded; the extruded materials are attached to a quenching roller and are quickly cooled to form a casting sheet; the casting sheet is preheated in transverse stretching equipment, and is transversely and uniformly stretched for four times, set and cooled to obtain the degradable heat-shrink film.

Description

Technical field: [0001] The invention relates to the field of heat shrinkable film processing and manufacturing, and more specifically relates to an environmentally friendly degradable heat shrinkable film and a manufacturing method thereof. Background technique: [0002] Heat shrinkable film is widely used in the outer packaging of tableware, food, health care products, beverages, photo frame products, books, audio-visual products, stationery and paper products, handicrafts, building materials, cosmetics, electronic products, daily chemical products, toys and other products. Heat-shrinkable film has the functions of tightening objects, covering, moisture-proof and dust-proof, stabilizing, protecting products, and improving product grades. [0003] Nowadays, with the rapid development of heat shrinkable packaging, the amount of heat shrinkable packaging products is increasing. We know that today's heat-shrinkable materials are mainly concentrated in PVC, OPS, OPP, SBS, PET,...

AI Technical Summary

Problems solved by technology

We know that today's heat-shrinkable materials are mainly concentrated in PVC, OPS, OPP, SBS, PET, PETG and other materials. These materials themselves are non-renewable petroleum-based materials. Heat-shrinkable films have the following defects in the later stages of use as packaging films: 1. 1. The total output is very large, but the relative output flowing into the hands of end customers is very small, which is not worth recycling, and it is often discarded casually, causing white pollution; 2. When it is packaged as a bottle body, it is easy to have technical problems that are difficult to separate during recycling, resulting in It consumes a lot of manpower, material and financial resources, and increases the cost of recycling; 3. Most of the current heat shrinkable packaging films are petroleum-based materials, and nowadays petroleum materials are increasingly scarce, and the price of petroleum-based materials is also rising; 4. Even if it can be recycled Products, the complexity of product recycling and the inability to achieve accurate classification of materials under the existing social conditions, resulting in difficulties in later separation; The processing performance has changed, the processing suitability becomes worse when reprocessing, and the performance of the processed product becomes worse, resulting in recycled products that can only be used as low-end products even if they can be reprocessed; 6. Repeated recycling processing will only lead to plastic polymerization The processing performance of the object itself deteriorates

[0006] 1. In the film blowing process, plasticizers must be added to facilitate blow molding, and the plasticizers will migrate to the surface of the degradable film over time. The plasticizer itself is harmful to the human body, resulting in blow molding degradable heat Shrink film cannot be used for packaging food materials, thus limiting the scope of use of blown film forming biodegradable films

[0007] 2. Because there is no nano-silica modifier added in the blown film forming process, and the film thickness deviation of the blown film process is large, the printing performance of the blown film is poor, and the precise printing of the film cannot be realized

[0008] 3. Poor filtering effect of blow molding filter leads to debris in the mold cavity, causing logistics disorder, uneven discharge, and uneven thickness

[0009] 4. Due to improper adjustment of die lip gap and difficult control in blow molding, the melt discharge fluctuates and the thickness is uneven

[0010] 5. Blow molding products are not easy to control due to the cooling effect, resulting in poor transparency of blown film forming biodegradable films

[0011] 6. Due to the inaccurate stretch ratio of the blown film, the thermal shrinkage performance of the degradable heat shrinkable film is unstable

However, the process of preparing degradable heat-shrinkable film by unidirectional casting stretching has not been reported.

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