Water-Soluble Shopping Bag Using PVA and Composite Plasticizers
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Solution Overview
Problem
Conventional shopping bags, whether made of plastic or biodegradable materials, pose environmental pollution issues due to non-degradability and high manufacturing costs, limiting their widespread adoption.
Innovation Solution
A water-soluble shopping bag composed of polyvinyl alcohol (PVA) with added composite plasticizers, polysaccharides, processing aids, and film agents, allowing for thermoplastic processing and biodegradability, enabling visible degradation in water contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If polyvinyl alcohol (PVA) is used as the base material for the shopping bag, then water solubility and biodegradability are achieved, but thermoplastic processability deteriorates due to extremely poor process ability
Solution Approach 1:
The patent introduces composite plasticizers (including polyol, polyol ether, and fatty amine/fatty alcohol amine) as intermediary substances that mediate between the PVA base material and the thermoplastic processing requirements. These plasticizers modify the molecular structure and intermolecular forces of PVA, making it sufficiently processable through thermoplastic methods while retaining its water solubility and biodegradability properties.
Solution Approach 2:
The patent creates a composite material system consisting of PVA as the base material combined with multiple functional additives including composite plasticizers, polysaccharides, processing aids, and film agents. This composite approach allows each component to contribute specific properties: PVA provides water solubility and biodegradability, while the composite plasticizers provide thermoplastic processability, and other additives enhance mechanical properties and processing characteristics.
2Object-affected harmful factors
If biodegradable materials such as PLA, PBS and PBAT are used to make shopping bags, then environmental degradation is achieved, but manufacturing cost increases by more than 3 times compared to ordinary plastics
Solution Approach 1:
The patent employs PVA, a relatively inexpensive water-soluble polymer, as the base material instead of more expensive biodegradable materials like PLA, PBS, or PBAT. The shopping bag is designed as a disposable product that dissolves in water after use, eliminating the need for long-term durability. This approach achieves environmental friendliness through water solubility and biodegradability while maintaining cost-effectiveness suitable for widespread adoption.
Solution Approach 2:
The patent modifies the chemical composition and molecular structure parameters of the bag material by selecting PVA with specific polymerization degrees and alcoholysis degrees, and by adjusting the ratios of composite plasticizers and other additives. These parameter changes enable the material to achieve adequate mechanical strength and processability for shopping bag applications while maintaining water solubility and biodegradability, providing a cost-effective alternative to expensive biodegradable materials.
3Strength
If conventional plastic shopping bags made of polyethylene, polypropylene or polyvinyl chloride are used, then convenience and durability are provided, but white pollution is generated that damages soil and water quality
Solution Approach 1:
Instead of making the plastic bag resistant to degradation (conventional approach), the patent inverts the design principle by making the bag highly susceptible to degradation through water solubility. The PVA-based shopping bag is designed to dissolve in water after use, transforming from a persistent pollution source into a transient product that naturally degrades. This inversion resolves the contradiction between durability during use and environmental harm after disposal.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution provides a biodegradable and water-soluble shopping bag with improved bearing capacity, low environmental oxygen consumption, and visible degradation in water, reducing pollution and costs while being suitable for anhydrous environments.
Implementation Method 1
polyvinyl alcohol has biodegradability, and its biological oxygen consumption and chemical oxygen consumption in water are extremely low, thus causing no pollution or damage to water quality. The dissolution of polyvinyl alcohol into the soil not only does not cause pollution and damage to the soil
Implementation Method 2
the polyvinyl alcohol (PVA) is effectively plasticized, internally and externally processed and lubricated, so that polyvinyl alcohol is effectively processed and molded through thermoplastic processing
Implementation Method 3
the polyvinyl alcohol (PVA) is effectively plasticized, internally and externally processed and lubricated, so that polyvinyl alcohol is effectively processed and molded through thermoplastic processing
Data Source
Figure 1~4b
AI summary
The present invention relates to a water-soluble shopping bag and a preparation method thereof. The water-soluble shopping bag consists of the following components according to the following parts by weight: 100 parts of polyvinyl alcohol; 8-20 parts of a composite plasticizer; 10-30 parts of a polysaccharide derivative; 1 -5 parts of a processing aid; 0.1 - 0.5 parts of a film slipping agent; and 0.5-3.0 parts of a film anti-blocking agent. The preparation method comprises the following steps: mixing the components according to the parts by weight, extruding the mixture by means of a twin screw extruder to form pellets after mixing, then performing blow molding to form a film by means of a thermoplastic extrusion and film blowing machine, and then preparing various types and sizes of water-soluble shopping bags by means of a bag making machine. The water-soluble shopping bag has higher bearing capacity and cold water solubility, is suitable for use in water-free environment, and dissolves upon contacting water without producing pollution after being used.