Biodegradable polypropylene sheet
日期：2022/3/11 8:35:43 / 閱讀： / 來源：本站
Biodegradable polypropylene sheet1. Material selection and formula design
(1) PP resin is used to produce PP resin for blister forming sheet. It requires large relative molecular weight and wide relative molecular weight distribution, and there are a large number of long branched chains on the main chain. This structure makes the crystallinity of PP resin low, the springback of the sheet is sufficient during thermal forming, and the deformation is small, which eliminates the influence on the quality of PP sheet due to thermal sagging deformation, resulting in the discount of product forming. Therefore, PP resin with small MFR and relatively low regularity is selected. For some varieties and brands that can not meet the requirements, other additives need to be added to improve its processing performance. Here, the main materials PP are Yanhua pp1300 and Qilu ppt30s.
(2) Other additives are mainly PE resins with small MFR value. The purpose of adding other additives is to improve the viscoelasticity of the material and reduce the degree of sagging after heating.
(3) According to the structural characteristics of PP resin, the degradation agent mainly selects Pb photosensitizer (aminoalkyl ferrocene derivative), photosensitive synergist (hydroperoxide ROOH), bioactive agent (modified corn starch) and carrier PE. In order to facilitate production, several materials were mixed, extruded and granulated to make PP degradation masterbatch. Through the aging test of double degradable PP fast food box samples in continuous simulated climate for 300h on 150s insolation instrument, the degradation test results are compared and added. (4) (basic formula) 100 degradation agent 10: other additives 1520. Due to the degradation of medium and yellowish appearance of wood, it is in production
After or eliminating yellow light, the dosage (mass fraction) is less than 0.15%. According to the requirements of users, a small amount of matting materials that meet the hygienic requirements can be added and reduced appropriately
2. Main equipment
Si0ovfp200 single screw extruder with screw diameter of 100MN, manufactured by xianbo company of Japan.
3. Manufacturing process
(1) The process flow is shown in Figure 2-45. PP tree shop T-shaped die traction trimming coiling package Xin warehousing
Fig. 2-45 process flow chart of photo biodegradable PP extruded sheet (2) extrusion process conditions
1. Temperature: 180 ~ 240 ℃ for material profile, 210 ~ 230 ℃ for neck and 220 ~ 230 ℃ for die head. 2) Screw speed: 70 ~ 90r / min. 3) Cooling: water temperature 30 ~ 50 ℃. 4) The drawing and drawing speed is related to the gap between the T-shaped die and the extrusion speed, and directly affects the tensile degree of the sheet, which is an important factor affecting the service performance of the sheet. 4. Performance 1) appearance. After the instrument aging test for 51h, the double degradable PP Lunch Box samples showed small cracks. Up to 250h, all the samples formed turtle cracks, and some samples were broken, but the non degradable PP Lunch box had no obvious change before and after aging. 2) Relative molecular weight. The statistical results of relative molecular weight changes before and after aging are shown in table 2-73. 3) The hygienic performance and application requirements of photo biological double degradable PP sheet and products meet the standards gb9688-1988 and TB / t2611-1994, and the degradation performance effect of the products is obvious. The degradation time of the lunch box products produced with this sheet can reach 60 ~ 90 days in winter and 30 ~ 30 days in summer, meeting the requirements of environmental protection.
Change ratio of relative molecular weight before and after aging
Decline rate of relative molecular weight before aging after aging (%)
Mw Mn Mw Mn Mw Mn
19.85 4.83 14.07 3.75 36.6 30.7
Noodle flavor solution lunch box 23.99 5.32 1.45 1.11 94.0 79.0
4. There is no "three wastes" in the process of oil and water production. Compared with the pulp production process for paper lunch boxes, it does not consume wood and destroy the forest, and more directly avoids the pollution of air and soil caused by waste gas and wastewater produced in the process of papermaking.
Example 81pp / ethylene vinyl alcohol copolymer (EVOH) Co extruded sheet
1. Sheet structure
PP / EVOH coextrusion sheet takes EVOH as the barrier layer, which is covered with PP structural material layer with good moisture resistance and steam resistance, and the adhesive layer is between PP and EVOH. Therefore, PP / EVOH coextrusion sheet is a five layer coextrusion sheet, and its structure is PP / AD / EVOH / AD / PP (abcba), as shown in figure 2-46.
2. Material selection and performance
(1) EVOH EVOH resin is a semi crystalline thermoplastic resin with molecular formula:
[(Chch, CH-CH) 3ohevoh is the product of complete hydrolysis of ethylene vinyl acetate copolymer. At present, the main manufacturers in the world are: Japan kelaoli company, Japan synthetic chemical industry company, American Eval company and Belgium Solvay company.
The gas resistance of EVOH is about 100 times greater than that of PA, 10000 times greater than that of PP and PE, and 10 to tens of times that of PVDC.