The new standard of GB/T9774-2020 " PP Woven Bags for Packaging Cement ", the official implementation date of this standard is April 1, 2022.
With the release of the new standard, the PP Woven Bags for Packaging Cement type will be completely "abandoned and replaced with paste", that is, the seamed bottom bag type will be completely eliminated, and the PP Woven Bags for Packaging Cement will only be limited to the square bottom valve type.
After the implementation of the new standard, it marks the historic reform of cement packaging bags in my country, which not only conforms to the national environmental protection policy, but also provides an opportunity for packaging enterprises and cement enterprises to achieve high-quality development in an all-round way. Ash is a serious problem that causes environmental dead ends.
After the implementation of the new standard, cement companies will face many challenges. Although there is no mandatory implementation at present, they should prepare in advance to better implement the new standard, which is also an inevitable trend in the context of "double carbon". If the new standard square bottom valve bag is not replaced, once the state starts to enforce it, it will be too late!
When replacing packaging bags, cement enterprises mainly face the following problems:
1. The technical transformation of cement packaging machine, the manipulator automatically inserts the bag instead of manually inserting the bag;
2. The square bottom bag is matched with the filling machine, which not only ensures the normal filling of cement, but also ensures a reasonable relationship between air permeability and moisture-proof performance; 3. The secondary bag cleaning system of the belt conveyor further ensures a clean environment;
4. Automatic loading system of bagged cement, automatic stacking and loading of manipulators instead of manual loading and unloading, etc.
Main technical changes of the new standard
(1) Technical requirements
1. The bag making process is modified from the original paste bottom bag and seam bottom bag to a square bottom valve bag with adhesive and heat sealing.
2. The bag making material is increased. For the requirements of plastic woven cloth and plastic film, the quality of the film should be greater than 18g/m.
3. Added bag type requirements
4. The physical performance requirements of film-coated plastic woven bags and paper-plastic composite bags have been revised.
5. The applicable temperature of film-coated plastic woven bags and paper-plastic composite bags has been changed from the original three grades of no higher than 80°C, no higher than 90°C, and no higher than 100°C to one grade of no higher than 100°C.
The firmness of film-coated polypropylene woven bags and paper-plastic composite bags is increased by 6.
The bag is not broken after 8 drops, modified to 6 times without breaking the bag
(2) Test method
1. Add bag type detection, and use visual inspection to judge the bag type. 2. The sampling of the mass per unit area test is changed from the original two 100mmX100mm square samples to two 0.01m2 round samples.
3. Standardize the process of making small bags for moisture-proof performance and the influence of bag-making materials on cement strength.
4. The moisture-proof test curing system was revised, and the curing humidity range was changed from the original 90% ± 5% RH to 80% ± 5% RH. The maintenance and placement requirements are refined: the small bags are arranged in a stacking type, and the bottom and top of the small bags are stacked with dense moisture-proof hard partitions, and then compacted with a total mass of 2000g items, and the number of stacking layers is small. in packs of 10.
The new version of the standard deletes the bag type of the bottom seam bag, deletes the code of the bottom seam bag, deletes the basic size of the bottom seam bag, deletes the inspection report, deletes the arbitration, deletes the newly developed packaging bag stereotype approval, and modifies the packaging bag filling. Packing process suitability test, modified bag bottom width and allowable deviation.
Excerpted from China Plastic Products Committee