Company Name: Linyi Yongfeng Plastic Knitting Factory
Contact: Ms. Zhou / Mr. Wang
Address: No. 17, Row 7, Plastic Market, Lanshan District, Linyi City, Shandong Province
The finished plastic woven products are the tense category of finished plastic products in China. China has become a big country, a big country and a big importer of plastic woven products. In recent years, the annual output of plastic woven products has increased by more than 20%. The new national standard for plastic woven bags has been approved and implemented by the process. The main purpose of the new national standard is to implement the goal of lightweight packaging, withdraw the request for the weight of the bag, and use the strength of the bag as a tense target for auditing, that is, regardless of the size of the bag itself, you only need to be satisfied with the strength target. In the future, competition in the market of plastic woven products will be dominated by light weight, high strength and low prices.
PET, with its rich origins, absolutely expensive price, and specific strength far higher than polypropylene, has entered people's sight. In addition, PET has many excellent functions that PP does not have. It is a new era in which PET is used as a tense material to produce plastic products. Is striding towards us.
►PET as a plastic woven product superiority
Rich and solid material origin
Millions of tons of PET flakes are produced and imported at home every year.
PET bottle flakes have higher specific strength than PP
As a new material, the density of PET exceeds 50% of that of PP, but the tensile strength is more than twice that of homopolymer PP, which means that when the tensile test is stopped, the specific strength values are similar. . After one-time use of PET bottles, if they are accurately received and taken over for disposal, their data functions can still reach the level of new materials, and polypropylene will be significantly degraded every time it is heated and cannot be repaired. PET bottle flakes should have a higher specific strength than PP doped with receiving and receiving materials.
Among synthetic resins that use kerosene as the tense root material, the price of PP is absolutely cheap, but it still runs at a high level with the soaring domestic kerosene price, and because PET bottles are more and more, it is used for the market of short fibers. The price has not changed much over the years, only equivalent to 50 ~ 60% of PP.
Superior aging resistance
One of the biggest shortcomings of PP plastic woven bags is that they are not resistant to aging. PP plastic woven products without antioxidants and light stabilizers are quickly powdered in the sun, and polyester can still maintain superiority after several months.
Good high temperature resistance
Another great achievement of PP plastic woven bags is that they become brittle at high temperatures, while the brittleness temperature of PET is very low, and even in the coldest summer, they can be fully packed without cracking.
High light transmission
From the polyester bottle, it can be thought that the amorphous PET is complete and transparent, which is extremely tight for the packaging of some items.
Wide surface, elegant and conducive to filling
Do not chop when weaving
In the orientation of PP, the large components are linearly divided along the tensile force, and the weak inter-molecular influence force, which is perpendicular to the tensile force, is the van der Waals force. It is easy to produce signs of splitting under the tension of the braiding machine. It is more likely to occur when there are signs of moderate stretching. The molecular structure of PET determines that even if there are moderate signs of stretching, its vertical influence is upward and there is a strong inter-member influence, so no signs of splitting will occur during weaving.
Good creep resistance
PP plastic woven products under permanent force will produce irreversible permanent deformation, that is, creep, especially when the external force is large or subjected to external force for a long time, while PET plastic woven products can almost be the same as metal materials under external force. Permanently irreversible dimensional changes. This is very tense for the tote bag.
PET materials have many other advantages such as fatigue resistance, friction resistance, folding resistance, acceptability and environmental protection, hygiene, etc., which can be used in the application of plastic woven products.
►Technical difficulties and sticking points of using PET bottle flakes to make finished products
In the future, the production techniques and equipment for using PET bottles to make woven products have become increasingly perfect. From the understanding of R & D companies, the crux of their nervous skills are as follows:
The melt viscosity of PET is low, and it cannot be indirectly water-cooled to form a film after being cast away from the open die like PP, but it must be cast onto a cooling drum to indirectly cool to form a film. The drawing machine based on the original PP plastic woven product cannot be used for PET bottle flakes.
PET bottle flakes must be sufficiently complete and boring, so that the water content reaches 0.03%, and the ability to stop drawing processing is as follows.
After the PET bottle flakes are formed into filaments, the unidirectional stretching temperature and stretching ratio are different from those of PP, and the flat yarns that only need to obtain the proper stretching ratio have the ideal tensile load.
The thickness of PET flat yarn can and must be smaller than PP, which has the competitive advantage in price.
At present, the processing results of supplementary masterbatches applicable to PET have not yet been processed, and the processing of excess results of PET's efficacy and the addition of excessive amounts of mineral powders such as calcium carbonate are natural, especially when the plastic woven bag is requested to be unclear, it is even more necessary to participate in the supplementary masterbatches Or masterbatch.
The plastic woven bag made of PET bottle flakes is too slippery on the outside and poorly palletized. The external friction coefficient should be improved through modification.
At present, the plastic woven bag made of PET bottle flakes does not have a suitable coating material. The peel strength of the current coating material is too low.
It can be used for melt extrusion of PET bottle flakes drawing system, eliminating wet and dry extrusion processing skills and equipment. As far as the dryness of PET bottle flakes is concerned, the requirements are severe. The hot air boring equipment used on weekdays not only consumes high energy, but is also difficult to be boring. Once the time is prolonged, the material will turn yellow, and if it is not applied immediately after boring, it will quickly receive the moisture in the surrounding environment. Within 30 minutes The water absorption can reach 500ppm (0.05%), and the equilibrium water absorption can reach 0.4%. Such PET materials with a water content can not be melted indirectly.
The presence of water in PET materials is divided into adsorbed water and association water. The former can be removed at 120 ° C, while association water needs to be removed at 140 ° C and above.