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PROCESSING
TEMPERATURE
THE PROCESSING TEMPERATURE OF BIO-DEGRADABLE PACKING
FILM IS LOWER THAN THAT OF ORDINARY PACKING
FILM.USUALLY,WHEN THE BM BIODEGRADABLE MOTHER BATCH
CONTENT IS 30%,THE PROCESSING TEMPERATURE IS 10℃～20℃
LOWER THAN ORDINARY PACKING FILM.THE HIGHER THE BM
BIODEGRADABLE MOTHER BATCH IS, THE LOWER THE PROCESSING
TEMPERATURE SHOULD BE, ESPECIALLY FOR THE MOULD HEAD.IF
NECESSARY,IT CAN BE TURNED OFF AFTER THE PLASTICS
BLOWING IS NORMAL.WHEN THE BM BIODEGRADABLE MOTHER BATCH
CONTENT IS ＜60%,THE TEMPERATURE DROPS MORE SIGNIFICANTLY
WITH THE INCREASE IN BM BIODEGRADABLE MOTHER BATCH,WHILE
THE BM BIODEGRADABLE MOTHER BATCH IS ＞60%,THE DROP OF
TEMPERATURE IS SMALLER WITH THE INCREASE IN BM
BIODEGRADABLE MOTHER BATCH,IN THE PLASTICS BLOWING
PROCESS,IF THE PROCESSING TEMPERATURE IS RAISED,THE
TEMPERATURE RISING SHOULD START WITH PLASTICIZING
ZONE,SINCE THE BM BIODEGRADABLE MOTHER BATCH IS VERY
SENSITIVE TO THE TEMPERATURE,THE TEMPERATURE-RISING
RANGE IS ABOUT 2℃ EACH TIME.IF THE PROCESSING
TEMPERATURE HAS TO BE DROPPED,THE TEMPERATURE DROPPING
SHOULD START WITH MOULD HEAD.IF NECESSARY,THE
TEMPERATURE OF EACH HEATING SECTION SHOULD BE DROPPED
EXTENSIVELY.THE RANGE IN PLASTICIZING ZONE CAN BE
SMALLER,AND THE RANGE AT MOULD HEAD CAN BE WIDER.
VARIOUS PROCESSING TEMPERATURES&ADJUSTMENT RANGES VARY
WITH DIFFERENT EQUIPMENTS.
EXTRUSION AMOUNT
THE EXTRUSION AMOUNT SHOULD NOT BE TOO LARGE.USUALLY
AROUND 80% OF RATED EXTRUSION AMOUNT；OTHERWISE， AFTER
EXTRUDER RUNS FOR A PERIOD OF TIME，THE FRICTION SHEAR
HEAT WILL RISE.(AS COMPARED WITH ORDINARY
POLYETHYLENE,THE FRICTION SHEAR HEAT IS HIGHER.THE
TEMPERATURE-RISING IS QUICKER AND THE RISING RANGE IS
LARGER)IT WILL CAUSE THE ACTUAL TEMPERATURE TO
RISE&BUBBLE EMERGENCE ON FILM SURFACE.
OTHER TECHNIQUES
⒈BLOW-EXPANSION RATIO：4:5:1～6:5:1
SOMETIMES 7:1 IF THE BM BIODEGRADABLE MOTHER BATCH
CONTENT IS ＞80,THE BLOW-EXPANSION RATIO SHOULD NOT BE
＞6.5:1.BECAUSE THE BM BIODEGRADABLE MOTHER BATCH CONTENT
INCREASES, THE STARCH CONTENT INCREASES
ACCORDINGLY.HOWEVER,WHEN THE POLYETHYLENE CONTENT
DECREASES.THE HORIZONTAL TENSILE STRENGTH OF MATERIAL IS
RESTRICTED SUBSEQUENTLY.WHEN THE BLOW-EXPANSION RATIO IS
TOO LARGE,THE FILM IS EASY TO RUPTURE DUE TO POOR FILM
STABILITY AND NON-UNIFORMITY OF FILM THICKNESS.
2.HEIGHT OF COOLING CURVE:SIMILAR TO ORDINARY LOW
PRESSURE PACKING FILM.
3.MOULD HEAD: LOW PRESSURE MOULDING HEAD WITH SHAPING
ROD. FOR EXAMPLE,(40% MOTHER BATCH) WHEN THE DIAMTER OF
MOULD MOUTH IS 100MM,THE PRODUCIBLE WIDTH OF
BIODEGRADABLE PACKING FILM IS 700—1000MM,THE
BLOW EXPANSION RATIO IS 4.8:1～6.5:1
WHEN THE DIAMETER OF MOULD MOUTH IS 40MM,THE PRODUCIBLE
WIDTH OF BIODEGRADABLE PACKING FILM IS 300MM～410MM,THE
BLOW EXPANSION RATIO IS 4.8:1～6.5:1
4.PHYSICAL PROPERTIES
TENSILE STRENGTH
THE TENSILE STREIGTH OF BIODEGRADABLE PACKING FILM IS
LOWER THAN ORDINARY PACKING FILM.THE HIGHER THE BM
BIODEGRADABLE MOTHER BATCH CONTENT IS, THE LOWER THE
TENSILE STRENGTH WILL BE.
FRACTURE ELONGATION RATE
SINCE THE PLASTICIZING STRENGTH,COOLING CURVE HEIGHT OF
FILM BUBBLE.BLOW-EXPANSION RATIO,STABILITY OF FILM
BUBBLE&THICKNESS HAVE INFLUENCE UPON FRACTURE ELONGATION
RATE TO A CERTAIN EXTENT.THE FRACTURE ELONGATION RATE
HAS A TENDENCY TO DROP WITH THE INCREASE IN MOTHER BATCH
CONTENT, BUT THE EFFECT IS LESS OBVIOUS ON TENSILE
SIRENGTH.
DART IMPACT STRENGTH
THE DART IMPACT STRENGTH OF BIODEGRADABLE PACKING FILM
IS LOWER THAN ORDINARY PACKING FILM,BUT THE INFLUENCE IS
NOT SO SIGNIFICANT.
5.NOTICEABLE PROBLEMS IN THE PROCESS OF PRODUCTION
IF THE BM BIODEGRADABLE MOTHER BATCH CONTENT EXCEEDS
60%, THE ORDINARY POLYETHYLENE CAN BE USED AT FIRST
WHILE LIFTING THE FILM.ONCE THE PLASTICS BLOWING
BEACOMES NORMAL,THE MATERIAL CONTAINING BIODEGRADABLE
MOTHER BATCH CAN BE PUT INTO PRODUCTION.
WHILE PRODUCING BIO-DEGRADABLE PACKING FILM ,THE CHANGE
OF SCREEN CLOTH IS MORE FREQUENT THAN THAT OF ORDINARY
PACKING FILM. THE HIGHER THE BM BIODEGRADABLE MOTHER
BATCH CONTENT IS.THE SHORTER THE INTERVAL WILL BE.FOR
INSTANCE, THE SCREEN CLOTH SHOULD BE CHANGED ONCE EVERY
12HOURS FOR ORDINARY PACKING FILM. THE SCREEN CLOTH
SHOULD BE CHANGED ONCE EVERY 8 HOURS FOR 30% BM MOTHER
BATCH. THE SCREEN CLOTH SHOULD BE CHANGED ONCE EVERY 5
HOURS FOR 60% BM MOTHER BATCH. PRIOR TO SHUT DOWN,THE
SCREW&MOULD HEAD SHOULD BE CLEANED WITH PE MATERIAL, IN
CASE OF LONG TERM PRODUCTION,THE SCREW&MOULD HEAD SHOULD
BE CLEANED PIRIODICALLY(ONCE EACH WEEK).IT IS BETTER TO
OPEN THE PACKAGE WHILE USING THE BM BIODEGRADABLE MOTHER
BATCH,OTHERWISE IT WILL ABSORB THE MOISTURE&MAY CAUSE
THE BUBBLE EMERGENCE ON FILM.THE HOPPER SHOULD BE
COVERED.
THE TRANSPARENCY OF BIODEGRADABLE PACKING FILM IS POORER
THAN THAT OF ORDINARY PACKING FILM,WHILE THE OPENING
PROPERTY IS BETTER.
WHILE PRODUCING THE COLOURED BIODEGRADABLE PACKING
FILM.THE QUALITY OF COLOURED MOTHER BATCH GRANULES CAN
AFFECT THE QUALITY OF THE FILM, THEREFORE,IT IS BETTER
TO CHOOSE COLOURED MOTHER BATCH GRANULES WITH GOOD
FLOWABILITY,GOOD DISPERSITY AND GOOD PLASTICITY.BECAUSE
OF THE SPECIALITY OF BM BIODEGRADABLE MOTHER BATCH,WHILE
PRODUCING THE PACKING FILM WITH A THICKNESS OF MORE THAN
0.02MM TO ADD CERTAIN AMOUNT OF REGENERATIVE MATERIAL IS
PERMISSIBLE,BUT THE REGENERATIVE MATERIAL MUST BE PURE
AND CLEAN.BESIDES,THE ADDITION CAN NOT EXCEED 50%. |
