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Quality testing methods for corrugated base paper, paperboard and carton

Date: 2021-12-23 19:34
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Abstract:

Corrugated base paper, paperboard and cartons Quality inspection method

 

1 Base paper

In order to standardize the various conditions that affect the paper properties, it is necessary to control them reasonably and effectively. In the UK, for example, the test is usually carried out at a relative humidity of 50% and a temperature of 23 ℃. Specimens shall be properly placed within 24 hours before testing.

1、 Determination of water absorption

The recognized method is Cobb method, but it is only suitable for tissue paper. First, clamp the metal ring or cylinder with both ends open on the paper of given area and weight, so that the paper can effectively close one end of the metal ring or cylinder. Measure the quantity of water (usually 25m) l )Pour into the water storage area, and pour out the residual water after the specified time. At this time, reweigh the paper sample, know the weight difference before and after the water absorption can be calculated, so as to compare the water absorption of different paper. Generally, the test time is about one minute, and the time will be adjusted only when the paper is especially hygroscopic. (recommended instrument: kby-1 cober tester + dl-125 cober sampler)

The water drop method can be applied to all kinds of paper. This method is relatively easy, but the results are not enough * *, but it can be tested anytime and anywhere to compare different papers. Usually, first draw a circle on the paper as a mark, drop a small amount of water into the center of the circle, and calculate the water absorption of the paper by measuring the water absorption time, that is, the time when the circle is wet.

2、 Air permeability test (paper hole number determination )

The commonly used method is the Gurley test, which still needs to be determined, but this time it is the time taken for a given amount of air to pass through a specified area on the paper (here used as a diaphragm) at a specified pressure. (recommended instrument: tqd-1 air permeability meter)

The fixed area on the paper is defined by a ring gauge. Then the compressed air passes through the "diaphragm" under the pressure of the specified air pressure, and the amount of gas permeated can be measured by manometer. Air permeability is usually expressed in [ml / min]. The bendsten method is similar to this method.

3、 Ring crush strength test (RCT)

During the test, a 152 mm (6 inches) long, 12.7 mm (1 / 2 inch) wide paper tape is put into an annular groove of a thick steel plate. The steel plate is placed horizontally, and the length of the paper tape is just enough to form a drum along its annular groove. A horizontal steel plate is placed on top of the paper roll, and then the paper is continuously pressed until it is crushed. The applied pressure is the RCT index of the paper, usually in Newtons. This method is mainly used to test face paper, but it can also be used to test corrugated core paper. The RCD index of these paper can provide a good reference for the final edge strength of paperboard formed in the future. (recommended instrument: hsd-a compression tester + hyd ring pressure sampler)

4、 Compression strength test of corrugated paper CCT

This method is specially used for the determination of corrugated paper. As in the flat compression strength test (CMT) of corrugated core paper, the paper becomes the same core paper on the tile line after passing through the cold pressing corrugated core paper forming machine. As mentioned in the above-mentioned RCT test procedure, the core paper is also subject to pressure, and its compressive strength can be calculated at the moment of crushing. (recommended instrument: hsd-a compression tester)

5、 Short moment compressive strength test (SCT)

Neither the RCT test nor the CCT test can be repeated, because the shape or vertical state of the paper under pressure may change, and the re test results will not be very * *. Therefore, in order to maintain the consistency of the test, people have developed a test method for short moment compressive strength of paper. The 15 mm wide paper tape is clamped firmly with two splints, leaving a gap of 0.7 mm (0.030 inch) of free paper in the middle. One of the splints moves along the plane of the paper tape to the other under hydraulic pressure to squeeze the narrow paper tape in the middle. It is also necessary to measure the pressure when the paper is crushed. This test can be done in both MD and CD directions. (recommended instrument: hsd-dj short distance compression tester)

6、 Flat compressive strength test of corrugated core paper (CMT)

In the early stage of corrugated board production, it is necessary to determine the flat compressive strength of different corrugated core paper, so the corrugated core paper test device came into being. This time, 152mm x 12.7mm (6in x 1g2 inch) paper tape will be put into the cold pressing core paper forming machine similar to that on the single-sided machine, and then the core paper can be changed. The core paper can also be formed under the action of a hot roll on a single-sided machine, but it should be stored for a period of time after the adhesive tape is applied. The purpose of adhesive tape is to imitate the single-sided paperboard to ensure that the core paper does not deform after being removed from the single-sided machine. This single-sided tape can then be put under pressure and can also be used for rc-d test and cc-d test. After the paper tape is compressed, there may be two kinds of crushing situations in CMT test: either the corrugated tape "unfolds" or the side is damaged. In this way, core paper and face paper can be compared and tested. In the same way, we can also use the single-sided paper produced by the single-sided machine to test and compare the actual value and theoretical value of CMT. (recommended instrument: hsd-a compression tester + PYD flat pressure sampler)

Carry out ( Hot core paper ) Test to let the sample paper through the hot single-sided machine corrugated stick, and then put it in the splint, repeat the above steps.

7、 Moisture test

Hand held hygrometer is widely used for moisture testing. The paper color or surface finish should be calibrated before using the hygrometer (recommended instrument: fd-g1 rapid moisture meter)

8、 Scott interlaminar adhesion test

Stick one end of the sample paper to the metal base and the other end to the top corner member. Strike the vertical face of the corner member with a pendulous pendulum until it separates from the pattern. The energy required to achieve this separation is usually expressed in Joule / m2. (recommended instrument: bl-cj interlaminar peel tester)

Other tests done by paper mills include pH test, paper brightness and smoothness test, etc.

9、 Burst test (also applicable to corrugated board)

The common method is Mullen test method, in which an extended hydraulic elastic circular diaphragm is provided, and a similar paper or paperboard disc sample is placed on top of it, and the disc sample is clamped on the diaphragm. The liquid pressure at the time of rupture of the specimen is recorded, i.e. the Mullen test value of the specimen, usually in 'kJ / m2'.

Paper and board thickness test (recommended instrument: npd-d) Burst tester )

A micrometer is used to measure the thickness of paper and paperboard. The micrometer can control the pressure and change the anvil properly.

10、 Paper and board gram weight test

A sensitive test scale is commonly used in paper mills to detect the gram weight of unit paper and compare with the standard of our factory. Determine the weight and thickness of the paper, the density of the paper immediately known. This method can also be used to determine the weight of paperboard. (recommended instrument: dl-100 quantitative sampler + electronic balance)

 

2 cardboard

1、 Edge pressure strength test (ECT)

This test is very important, from which we can see the stacking strength of cartons made of this kind of paperboard, and the corrugated shape of the vertical carton surface is also vertical. This test is similar to that of CCT, CMT, RCT and FCT, in which the paper tape must be pressed, and the two ends of the tape should be well parallel and perpendicular to the axis. Ect value is the pressure value measured when the paperboard is crushed.

Ect value can be estimated slightly, that is, the RCT value of each paper and the CCT value of corrugated core paper (taking into account the paper shrinkage) can be obtained. When calculating the ECT value of composite corrugated board with structural thickness after initial bonding, 10% should be added (recommended instrument: hsd-a compression tester + BYD edge pressure sampler)

2、 Flat compressive strength test (FCT)

During the test, put the cut circular paperboard sample under pressure. As with the CMT test, there may be two cases of crushing - if not, it is most likely due to the ridge tilt. (recommended instrument: hsd-a compression tester + PYD flat pressure sampler)

3、 Bond strength test (PAT)

This test has a long history, used to test the bonding strength of corrugated core paper and face paper. The common tool is a special comb. The length of the protruding pin on the comb is twice the width of the board, and the diameter can be placed between the edges of the board under test. Insert one from each side of the rectangular cardboard sample‘ Then, pressure is applied to the two combs to separate them, i.e. the top and bottom paper are forced to separate the face paper and the core paper. The pressure value when corrugated core paper and face paper are torn is the pat value of the measured paperboard. The adhesive strength of each tissue can also be measured separately, depending on which side of the tissue the protruding needle is inserted into. (recommended instrument: hsd-a compression tester + BYD adhesive sampler)

After the corrugated core paper and face paper are torn, it is necessary to check whether the test is to make the bonding failure, or whether there is a problem with the adhesive strength between the layers of the paper. Generally, the latter is the case.

4、 Puncture strength test

The test element uses a pendulum with a pointed tool, which is dropped from a predetermined angle to punch through the cardboard sample. The degree of puncture will show the bursting strength of the board tested, and the value will be displayed on a gauge. (recommended instrument: zcb-d microcomputer puncture intensity meter)

All waste paperboard

The specified strength characteristics are as follows:

    . The rupture strength is related to the rupture and puncture strength of corrugated board;

    . The ring crush strength test (RCT) and short distance compressive strength test (SCT) require to measure the effect of face paper on the compressive strength of paperboard;

    . Scott's tractability test is used to measure the bonding strength of the fibers inside the tissue. This will test if the top paper is bonded to the core paper layer, which will lead to the paperboard delamination or surface peeling;

    . The waxing degree test was used to evaluate the peeling degree of tissue paper;

    . The water absorption of the top surface was tested by Cobb test, which was related to printability; The test is also carried out on the back to evaluate whether its adhesion characteristics are suitable for bonding corrugated core paper;

    . The top surface also needs to be tested to understand the smoothness, shadow level and shadow variables relative to printability;

    . Papermaking is very important, including uniform moisture content and non rupture folding ability.

 

3 carton

1、 Test on compressive strength of cartons

This test requires a lot of pressure and is used to determine the potential stacking strength of finished cartons - that is, how high a packed carton can be stacked. This depends not only on the compression strength of the top to the bottom of the carton, but also on the weight of the contents and their own characteristics. If the main containers (e.g. cans and bottles) containing articles have structural vertical strength and are closely arranged in cartons, the compressive strength of cartons will be improved. Of course, the pressure on the bottom of the carton stack determines the required compressive strength of the carton. (recommended instrument: ky-2a microcomputer carton compression testing machine)

The results of such tests are often far from the actual results. The reason for this difference is either the quality of paperboard is different, especially the adhesive strength of each side of paperboard is different, or the vertical cardboard surface of the carton is often deformed. These phenomena will occur in the process of loading goods, and even more in the process of sealing. The main reason is that the pressure line of paperboard is not clear and difficult to identify, or the indentation error is caused by improper or damaged line pressing tools. When folding the swing cover, it should be clean, otherwise the paperboard near the pressure line will bulge up, which may be crushed under the vertical pressure.

But the compressive strength of the carton also depends on the ECT value and perimeter of the carton and the thickness of the carton board. McKee formula is commonly used to calculate the compressive strength of cartons. The formula is as follows:

    BCT(kg)=1.515 x ECTO. 57 xTO. 87 x(L+W)0.47

Among them, ect is the edge crush strength (kg / cm), t is the thickness of paperboard (mm), l and W are the length and width of carton (mm)

2、 Drop Test

This kind of test is not only for the carton, but also for its contents and some packing board as a whole. In the first 50 years of the last century, the test method was somewhat "crude": the test box was thrown from the second or third floor windows onto the concrete pavement in the factory, and the results were observed with naked eyes or photos. Later, cartons were placed on trolleys, bumped down a hard surface along a slope or ramp, or rolled over cartons packed in rollers over obstacles. Now, people have developed a new type of seismic test equipment. (recommended instrument: dl-150 carton drop tester)

Nowadays, many manufacturers of electronic products have specified the drop test requirements in detail. They do not allow any loss of the contents. As mentioned above, this kind of test is not only the external packaging carton itself, but also the overall test of packaging design, packaging materials and specifications.

Corrugated base paper, paperboard and cartons Quality inspection method

Corrugated base paper, paperboard and cartons Quality inspection method