Honeycomb Paperboard Features and Testing

Honeycomb paperboard is a new type of packaging material that has developed rapidly in recent years. It is a new type of packaging material that is made of two-layer paper and intermediate honeycomb core paper. Because of its use of paper, paperboard is mostly made of 300 grams or so; core paper uses 120 grams or so of corrugated paper or tea board paper, and because its core paper is honeycomb, it has two upper and lower paper phases inside and outside the honeycomb. Bonding, so structurally determines the honeycomb cardboard has better rigidity of this corrugated cardboard. The appearance of honeycomb paperboard and the continuous improvement in its craft make it a great alternative to wood. Recently, there are quite a few manufacturers who have produced pallets of forklifts made of honeycomb paperboard instead of wooden pallets.

From the samples sent from various countries to the China Packaging Science Research and Testing Center for performance testing of honeycomb paperboard, we can roughly classify the honeycomb paperboard as follows:

1} Points from material

a paperboard honeycomb paper, that is, two layers of paper and honeycomb core paper bonded together;
b. Eucalyptus, wood composite bee cardboard, that is, the paper of the honeycomb paperboard has one layer of paper, and the other layer of three layers or fiberboard.

2} Structured

a single honeycomb paperboard;
b Multilayered honeycomb paperboards are stacked together to form a composite honeycomb paperboard;
Composite honeycomb paperboard composed of c-type corrugated cardboard and honeycomb paperboard.

In recent years, in order to meet the needs of users and scientific research work, we have taken into consideration the honeycomb paperboard industry standard and relevant national and international standards, and conducted the customer’s entrusted honeycomb paperboard and packaging products made of honeycomb paperboard as raw materials throughout the country. The test has accumulated some experience. The following only discusses the issues related to the quality of honeycomb paperboard and its testing methods, and talks about our understanding for reference by relevant manufacturers and users.

The number of items and items that affect the quality of the honeycomb paperboard are appearance quality and physical and mechanical properties. They are: thickness, moisture content, capacity, static bending strength, flat compressive strength, peel strength, breakage fracture, and the like. Among the indicators that affect the quality of serious defects in honeycomb paperboard are: flat compressive strength, static bending strength, and peel strength. These three indicators more closely reflect the physical and mechanical properties of honeycomb paperboard. According to our long-term performance testing of corrugated boxes and corrugated cardboard and the function and characteristics of honeycomb paperboard, during the test, the sampling methods of the test samples and the temperature and humidity adjustments of the samples are all in accordance with national standards. In order to ensure the accuracy of the test, the dimensional tolerances of the sample should be specified. The recommended dimensional tolerance of the sample is ±0.5 mm. Because the thickness of honeycomb paperboard is much larger than that of corrugated paperboard, the perpendicularity of the two adjacent surfaces of the test specimen and the relative parallelism of the two surfaces are required. It is recommended that the verticality tolerance is 0.2mm and the parallelism tolerance is 0.15mm,. The number of each test sample should be more than five. In addition, the test specimens for the static flexural strength and peel strength of honeycomb paperboard should also include two sets of specimens in both longitudinal and transverse directions.

Now that the thickness is 20mm and the honeycomb side is 8mm long, the honeycomb paperboard is taken as an example to briefly describe the test methods for the above-mentioned important parameters:

1} Flat compressive strength <br> Tested in accordance with GB1453-9187 "Test method for non-metallic sandwich structure or core flatness performance" standard.
Specimen size: 60×60mm (square sample);
Test equipment: Xin Li electronic universal testing machine. The upper and lower platens of this instrument are garden-shaped platens with a diameter of 20mm, and it has a sample crushing detector. It can measure the maximum load and deformation of the sample when crushing, in order to ensure the accuracy of the measurement.
Loading speed: V=1m/min
Calculation formula: flat compressive strength (Mpa) = P/S
In the formula: P is the breaking load, N.
S is the area under pressure, mm2.

Test Methods:
a. Accurately measure the length and width of each sample;
bㄝ sequentially place the sample on the center of the two platens of the instrument, load it at the set speed, and record the maximum load when the sample is crushed;
cㄝ Calculate the flat compressive strength of 5 specimens according to the calculation formula, and then take the arithmetic mean as the final test result.

2) Static bending strength <br> Tested in accordance with ISO5628-1990 "Paper and paperboard - Static testing methods for bending strength - General principles" and GB1456-1998 "Test method for bending properties of sandwich structures".
Sample size: width 60mm, length 200mm;
Span: 160mm;
Test equipment: Xin Li electronic universal testing machine, synchronously record the "load-deflection value" curve during the test.
Loading speed: V=5mm/min;
Calculation formula: Adopt the three-point loading formula recommended by ISO5628-1990 standard:
Flexural strength (mn·m)FL3/48db;
In the formula: F is bending force, N.
L is the span, mm.
b is the sample width, mm.
d is the deflection, mm.

Test Methods:
a. Accurately test the width of the specimen and the distance between two points;
b. In the sample surface loading position, that is 1/2 midpoint of the length of the sample, draw a line as a sign to ensure that the loading position is accurate;
c The width of the loading platen and support should be greater than or equal to the width of the sample;
d ㄝ loading platen and bearing in the contact area with the sample are added a hard rubber pad, the width of 10mm, a thickness of 5mm;
e ㄝ test each of the five samples in both vertical and horizontal directions, taking the arithmetic mean of the five samples as the value of the longitudinal or transverse bending strength of the honeycomb paperboard.
3. Peel strength Refer to GB/T2791-1995 “T-Peel Adhesive Strength Test Method, Flexible Materials for Flexible Materials”. However, based on the characteristics of honeycomb paperboard, we made some changes in the test method because of the honeycomb paperboard. The thickness is relatively thick, and we have doubled the width of the specimen in this standard to 50mm. In addition, when the sample is prepared, the end paper and the inner paper of the sample to be tested are separated and separated from the honeycomb core paper by 50-60 mm with a blade as a clamping part, and then are respectively clamped into the upper and lower chucks of the testing machine.
Sample size: width 50mm, length 200~250mm;
Test equipment: Xin Li electronic universal testing machine. Synchronously record the "load-stripping length" curve during the test;
Loading speed: V=15mm/min;
Calculation formula: Peel strength (KN/m) = F/B;
Where: F is the average peel force, N.
B is the sample width, mm.

Test Methods:
a. Accurate test specimen width;
b. The pre-striped face paper and paper (approx. 50-60mm length) are clamped into the upper and lower chucks of the testing machine and clamped. The upper and lower chucks are separated according to the set loading speed. The peeling length of the sample should be at least 125mm
c. During the peeling test, observe the destructive condition of the sample. If the paper or the paper itself tears and peels off, the sample should be discarded and the test repeated.

Honeycomb paperboard is a new type of packaging material, and our understanding of it needs to be gradually deepened and long-term experimental accumulation. The test methods for several major technical indicators of the above mentioned honeycomb paperboard are also tentative and immature. In addition, technical indicators such as moisture content, thickness, dynamic and static buffering performance are also relatively heavy and should be considered in practical applications.