Quality Evaluation of Pulp Molded Products
Quality parameters and measurement of industrial packaging pulp molding
At present, the quality of a pulp molded product in the pulp molding industry mainly depends on the following indicators: dimensions (length, width and height), weight, appearance, moisture content, color, water absorption, odor, pressure resistance, drop Experiment, vibration experiment, etc. Next, we will share the common standards and measurement methods of these indicators with you one by one based on your own work experience.
Measurement condition
The standard environment of sample state adjustment and test shall be carried out in accordance with the provisions of GB/T10739. The factory inspection is carried out under normal temperature and humidity conditions, and the standard environment is 23℃±1℃, and the relative humidity is 50%±2%. The sample pretreatment time is more than 24H (storage and standard environment).
Dimensions
The following table lists the national standards for length dimension deviation (pulp molded industrial packaging products)
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The measurement of the external dimensions mainly uses a steel ruler or caliper with a division of 1mm. At least 5 samples are measured, and the arithmetic average is taken, and the value is accurate to at least 1mm.
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Figure 1 Steel ruler
Picture Figure 2 Vernier caliper
Weight
The following table lists the national standards for grammage deviation (pulp molded industrial packaging products)
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Weigh the quality of the product with a universal measuring tool (generally an electronic scale) of suitable accuracy. Weigh at least 5 samples, take the average value, and calculate the quality deviation according to the following formula.
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Figure 3 Electronic scale
Exterior
The main requirements for the appearance of the product are:
①There should be no cracks in any form on the surface of the product (BB/T 0045--2007 stipulates that the crack width is less than 1mm and the length is less than 40mm);
②The surface of the product is smooth and has no missing or rotten edges;
③The product is impervious and has a uniform texture;
④The product has no accumulation, no lamination, and no defects;
⑤ Product appearance dust degree (or the number of different color points, the area meets customer requirements)
The appearance quality of the product should be inspected visually under natural light conditions.
Moisture content
The moisture content of the molded pulp product refers to the ratio of the mass of the molded pulp product reduced to the mass at the time of sampling after drying according to the specified method, and is generally indicated as a percentage;
For the pulp molding industry, a handheld moisture meter (as shown in Figure 4) can generally be used to determine the moisture content of the product, but if you want to accurately measure the moisture content of the product, you need to refer to GB/T 462-- -2003, using a drying oven (as shown in Figure 5), balance measurement.
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Figure 4 Handheld paper moisture tester
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Figure 5 Constant temperature drying oven
The moisture content X (%) should be calculated according to the following formula
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M1 is the quality before drying, and M2 is the quality after drying.
Drying conditions are: 105℃±2℃ drying box, the drying time is at least 1 hour. After the first drying, put the sample in the drying box to cool down, and then dry it again after cooling to room temperature. If the difference in mass of the sample after two dryings is less than 0.1%, it is considered that the weight of the sample at this time has reached a constant weight state.
colour
The color inspection of molded pulp products is mainly based on visual comparison with customers' signatures to avoid color difference. For some products with strict requirements, whiteness detection and color difference detection can be considered. The main measuring equipment used is whiteness detector and color difference meter (refer to Figure 6, Figure 7). Since most of the pulp molding companies do not carry out accurate numerical measurement of color indicators, I won't introduce too much here.
Picture Picture 6 Whiteness Tester
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Figure 7 Portable colorimeter
Water absorption
Select the mesh surface of the product and conduct the test in accordance with the provisions of GB/T 460. Adjust the width of the ink line to 1MM, and measure the width of the ink line after 30S, and it should be ≤2MM. At least three different locations need to be selected for measurement.
odor
Mainly based on the nose's olfactory perception, whether it will produce uncomfortable odors.
Anti-stress
The formula for calculating the maximum pressure resistance of molded pulp products is as follows
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among them
P---The maximum pressure that needs to be reached, N;
W---the quality of the transport package, Kg;
H---Storage height, m; (generally calculated as 3m)
h---Outer height of transport package, m;
f---deterioration coefficient, (recommended range 1.6~~2.0)
Use pulp molded products to properly package the packaging or simulants. Place the packaged objects and molded pulp products on the lower surface of the pressure testing machine (refer to Figure 8). Carry out the test in accordance with the provisions of GB/T 4857.16. Record the maximum pressure resistance and deformation of molded pulp products, accurate to 1N and 1MM. Test three sets of samples respectively, and calculate the arithmetic average of the test results. Under the maximum pressure resistance, the deformation of the molded pulp product should be less than or equal to 30MM.
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Figure 8 Pressure testing machine
Drop test
Simulate the situation when different edges, corners, and faces are dropped on the ground at different heights, so as to understand the damage of the pulp molded product and the packaged material, and evaluate the fall height and impact strength that the product packaging components can withstand when they fall. . In order to improve and perfect the packaging design according to the actual situation of the product and the scope of the national standard. Reference standard: GB/T2423.8-1995.
The drop test of general pulp molding companies is mainly for industrial packaging. The adopted drop test standard is a single color box drop, the drop height is 0.8m~1m, and the drop conditions are one corner, three edges, and six sides. After falling, the function of the packaged product is required, and the appearance cannot be changed. The overall structure of the molded pulp product is not destroyed.
