Our experience in the actual production process of can making and the information obtained from the end customer has the following reasons for causing the can sealant packing to extrude:
First, the choice of materials
In the material selection process, the manufacturer selects the proper sealant type according to the characteristics of the contents, and the sealant should have good plasticity, heat resistance, stability, water resistance, oil resistance, anti-oxidation solution, etc., to avoid the seal Canning and canning cause high temperature, high pressure sterilization, passivation treatment, and oil products cover the exhaust when the sealant filler extrusion and internal flow plastic. (See Table 1-1)
Main Products and Applications of Grace China Sealing Seals (Table 1-1)
Brand
Features
Uses
Color
Solid content
WBC480-35
gray
(35.0±1.0)%
(Water based)
Non-oil canned soups, meats, fruits, fish, milk, vegetables for various types of cans and steam jets for vacuum sealing process
WBC733P
gray
58.0%~60.0%
Suitable for hot or cold foods with or without steam jet sealing, high temperature or pasteurized food cans filled with water, acids, oils and fats
OP53BXMV
gray
(34.0±1.0)%
(Water based)
Applicable to all kinds of special-shaped cans that can be sealed without steam injection process, also applicable to the shaped cans containing various chemical solvents
OP649-40
red
(40.0±1.0)%
(Water based)
High oil and chemical resistance, suitable for cans of food cans, aerosol cans containing various chemical solvents
SLC100A/39LVS
gray
(39.0±1.0)%
(solvent based)
Suitable for all kinds of beverage cans and beer cans
SLC7704E/49
gray
(49.0±1.0)%
(solvent based)
Applicable to food cans, beverage cans, oil canisters containing less than 3% sanitary cans, vegetable cans
Second, the cover production process
1 Film weight: Excessive glue injection during the glue injection operation can easily lead to extrusion of the sealant filler. Usually the amount of sealant is mainly controlled according to the different cover diameters and the solid content of the sealant. (See Table 1-2)
Table 1-2 Recommended plastic injection amount for different can diameters and different solid content water-based sealants (health food round cans)
Can cover diameter
Dry film volume
/mm3
WBC480-30
WBC480-40
WBC480-56
Code number
Nominal/mm
Wet glue weight/mg
Adhesive weight/mg
Wet glue weight/mg
Adhesive weight/mg
Wet glue weight/mg
Adhesive weight/mg
202
52.3
39
170
51
128
51
91
51
211
65.3
50
217
65
163
65
116
65
300
72.9
53
233
69
173
69
307
83.3
60
260
78
195
78
139
78
401
98.9
71
307
92
230
92
164
92
404
105.0
82
360
107
268
107
190
108
502
130.0
107
463
139
348
139
250
139
601
153.4
130
563
169
423
169
300
169
Note: The glue injection tolerance is ±10%
(2) Radial distribution of film: The ratio of the amount of glue on the can and the amount of glue in the groove after the glue injection is usually controlled at 30% to 40% and 60% to 70%; the ideal injection amount is distributed in 2.1 turns; if the distribution ratio is out of balance Or there is heaping, spattering, and over-lapping amount of glue can lead to sealant extrusion.
3 Drying and curing: The sealant needs to be cooled and left to stand for 48 hours in the plastic injection process before it can be sealed. The water content of the film must be less than 2% when the film is capped. If the film is not cured completely or the cooling time is too short, the packing extrusion is likely to occur during the roll-sealing operation.
Third, can manufacturing process
The canning process causes the sealant packing to extrude due to improper adjustment of the indenter roller during the roll-sealing operation. This to avoid the occurrence of this quality problem should pay attention to the following points in the actual production control:
1 head curling roller * too tight
2nd roller hemming wheel * too tight
3 The length of hooks and hooks of the body should be consistent as much as possible, and the roll seal structure should reasonably reduce the deviation range so as to ensure reasonable top and bottom headspaces so that the sealant has a certain extension space.
Fourth, canned bactericidal cooling
Canned food in the process of high temperature and high pressure autoclave cooling effect sealant extrusion has three reasons:
1 The rationality of sterilization and cooling time and temperature, if the time is too long or the temperature is too high beyond the rated range, it will easily lead to extrusion of the filler. Canned cooling time generally varies depending on the type of food, can size, sterilization temperature, local water temperature, and water consumption.
2 The heat resistance of the sealant is poor or the sealant is not suitable for the contents. Easy to cause filler extrusion.
3 After sterilization, the cans should be partially or fully cooled. During the cooling process, attention must be paid to changes in the pressure difference between the inside and outside of the cans. The internal and external pressure difference should be maintained as much as possible to prevent the cans and can lids from being exposed to strong tension to cause the sealant to fill. Extrude.