Analysis on matters needing attention in formulation design of pe preservative film
According to the material characteristics and casting production characteristics, the melt temperature is controlled at 250 ~ 270 ℃, the temperature of casting roller is controlled at 23 ~ 28℃, winding tension is controlled within 98N. The above is the process of preparing PE film. However, attention must be paid to the pe preservative film formula in the preparation process, otherwise it will have shortcomings.
PE is safe and nontoxic. The film made of PE has moderate water permeability and air permeability, and is suitable for food preservation. However, ordinary PE preservative film has the following disadvantages: low transparency and poor anti-fog effect, can not well reveal the contents of the package; Poor flexibility, difficult to stretch; Poor retraction and different packaging products; The bottom surface of the shallow plate has poor adhesion and is easy to spread.
There are two reasons for the above shortcomings: first, PE is a crystalline material, which is easy to crystallize, resulting in poor transparency, flexibility and retraction of PE films, and difficult to stretch; It is difficult to obtain good anti-fog effect due to crystallization; Second, PE material itself does not have viscosity, so the viscosity is poor, which leads to poor adhesion of the bottom surface of the shallow plate and easy to disperse. Therefore, there are three improvement directions for the above reasons: first, reduce the crystallinity of PE film to improve the transparency, flexibility and retraction of the film; The second is to improve the viscosity of the film; The third is to choose the appropriate anti-fogging agent. It is difficult to meet the technical requirements for simple crystallinity reduction and viscosity improvement, and it must be a coordinated balance of various properties.
Analysis of pe preservative film formula design considerations
In view of the shortcomings of ordinary PE preservative film, the research is carried out from several aspects such as the selection and dosage of processing methods, substrates, enhancers and antifogging agents, flexibility and retraction improvement, attention should be paid to the formulation design of highly transparent and soft PE plastic wrap:
(1) PE is safe and non-toxic, its film is permeable and breathable, suitable for food preservation, so the substrate is PE;
(2) PE itself is not sticky, so it is necessary to add appropriate emulsion to facilitate shallow packaging;
(3) In order to reduce the crystallinity of PE film and improve its flexibility and retraction, an appropriate proportion of flexibility agent should be added;
(4) PE film has no anti-fog effect, and appropriate amount of anti-fog agent should be added.