The determination of the amount of glue is one of the important considerations in the production of composite flexible packaging. The amount of glue has a direct bearing on many properties of the product, such as the composite film's violent strength, resistance to media, appearance, and hardness.
When the amount of glue exceeds 6 g/m2, it loses its meaning, its performance is saturated, and it also causes many side effects such as slippage and cost increase. The amount of glue involved also involves product costs. Based on years of experience, reference can be made to Table 1 on dry composite films.
According to the purpose of the amount of glue requirements
classification
Film properties and uses
Dry base coating weight (g/m2)
General purpose
Transparent and smooth film
1.5-2.5
Printing film, aluminized film, coating film light-packed water-containing packaging
2.5-3.5
Contains chemical media content
3.5-4.0
Boiling sterilization
100 boiling
3.0-3.5
Cooking sterilization
Transparent
3.5-4.0
Aluminum foil layer
4.0-5.0
method one:
Theoretical estimation method
W=(1/4 to 1/6)μND
W-dry glue amount g/m2
Μ—net depth of gravure on gravure
N—% concentration of glue
D—density of glue liquid
The empirical coefficient is related to the dot shape of the rubber roller, the use condition, the pressure and elasticity of the pressure roller. Generally, the corrugating roller takes 1/4, the engraved rubber roller takes 1/6, and actually takes 1/5.
Method Two:
Total method
W = (adhesive usage × 1000 × solids content %) / processing area = G × N/l × d × 1000 (g/m2)
W-dry glue amount g/m2
N—% concentration of glue
l—The length of the composite film that has been produced m
D—gluing width, ie rubber rubber roller width m
For one or more rolls of composite film that have been produced, the amount of adhesive in the glue bucket before and after compounding is weighed, which is the total amount of glue, and the compound length is obtained from the meter counter to calculate the amount of glue. This method is simple and easy, but it also has obvious defects: first, it is not possible to control and monitor the production process. It is an afterthought. Second, the distribution of adhesive coating cannot be understood. Third, due to acetic acid. The use of ethyl ester has an error in the amount of coating. The total law is calculated in another way:
W=(W main×N main+W solid×N solid)/ld×1000(g/m2)
W main-main agent usage kg
N main-host solid content%
W solid - curing agent usage kg
N solid-curing agent content%
Method 3:
The weight difference method first cuts the two films to be composited into a size of 10 cm×10 cm, weighs the two pieces and adds them together. The weight is W1, and the composite film is also cut into a size of 10 cm×10 cm. When the weight is W2, the amount of sizing is (W2-W1) x 100. This method is simple. However, due to the problem of the uniformity of the thickness of the film substrate and the unevenness of the amount of ink, the error is large.
Method 4:
The direct coating method first trims three pieces of film with a width of 10 cm and a length smaller than the circumference of the top roller. The sum of the weights is called W1, and then it is stuck at the left, middle, and right points on the pilot film. After coating, weighing the sum of its weights to W2, the sizing amount can be calculated. The accuracy of this method is high, and the measurement can be averaged at the same time.
Method 5:
The solvent removal method combines the untreated side of the film with untreated. The composite film was cut to 10×10 cm and the weight was W1. After the composite film is peeled off, the adhesive on the film is wiped clean with ethyl acetate, and the sum of the weights of the two films is said to be W2, then the coating amount is (W2-W1)×100
This method requires wiping the adhesive and measuring the weight after the solvent has fully developed. This method has the highest accuracy and can measure the uniformity of the sizing distribution.
Source: Huashi Chemicals