A method for controlling the interlayer bonding strength of paper

Abstract

The application discloses a method for controlling the interlayer bonding strength of paper, which comprises the following steps: step S1, pretreatment, the multi-layer paper is pretreated, the fiber layer which does not need to be detected is peeled off, and only the detection layer to be detected is left; step S2, the detection layer is detected by an interlayer bonding strength tester; step S3, step S2 is repeated, the detection layer paper samples of different layers are detected respectively, the bonding strength of the corresponding detection layer of the paper is obtained, and the bonding strength present situation and problems of each layer are analyzed; and step S4, the content of the additive or the type of the fiber in one or more detection layers of the paper is adjusted, the bonding of the one detection layer or the different detection layers is controlled, the Z-direction strength of the paper after the adjustment is adjusted, and the single-layer detection or the interlayer detection of the multi-layer paper and the control of the bonding strength are realized.

Description

[Technical Field]

[0001] This invention relates to a technology for controlling the interlayer bonding force of liquid-coated paper, and more particularly to a method for controlling the interlayer bonding force of paper. [Background Technology]

[0002] In the process of using paper, different types of paper need to possess different physical properties. The main factor determining the use of paper is paper strength, which refers to the application performance exhibited by the paper after it has been made, including dry strength and tear strength when subjected to external forces. When paper is wet, its strength is significantly reduced, at which point the paper exhibits wet strength, as well as mechanical properties such as folding endurance and ring crush resistance; these application performance indicators are determined by the bonding strength between the paper fibers.

[0003] The mechanical properties of paper are determined by many factors, primarily the pulp raw materials and the production process. Firstly, the type of pulp fiber plays a decisive role in the mechanical properties of paper; different fiber types exhibit varying average lengths and uniformities. The fillers and additives used in the papermaking process also influence paper strength. Secondly, in production practice, the process parameters at each stage also affect paper strength; for example, the pH environment of the pulp, drying temperature, and pressing operations. Generally, to improve paper strength, the bonding strength between fibers must be increased. In papermaking wet-end chemistry, additives are often used to enhance this bonding.

[0004] In papermaking, when testing the entire sheet of paper using a bonding strength tester, the commonly used method is to test the paper bonding strength, that is, the bonding strength between paper fibers. This method mainly reflects the paper's internal ability to resist delamination, that is, the bonding strength between the paper and the paperboard. However, for multi-layered paper, this testing method can only detect the data between the two layers with the weakest fiber bonding strength in multi-layered paper, and cannot fully explain the differences in bonding strength between different paper layers.

[0005] Thus, during later use, due to insufficient control of bonding strength, paper delamination and tearing often occur. If most of the products in a batch are substandard, it will cause great quality risks to the production of subsequent products. Therefore, there is an urgent need for a method that can effectively test and control the bonding strength between paper layers. [Summary of the Invention]

[0006] This invention provides a method for controlling the bonding strength between paper layers. It can effectively detect the bonding strength between different layers of multi-layer paper in a short time, obtain the bonding strength between different layers of the corresponding paper and their layering positions, and analyze the current status and existing problems of the bonding strength of each layer. It is convenient to compare the bonding situation and changing trend between different fiber layers of the same paper, so as to carry out targeted regulation and meet the quality requirements of the product.

[0007] The technical solution adopted by this invention to solve its technical problem is:

[0008] A method for controlling interlayer bonding strength in paper, used for single-layer or interlayer detection and bonding strength regulation in multi-layer papermaking, includes the following steps:

[0009] Step S1, Preprocessing

[0010] The paper is pre-treated by manually peeling off the fiber layers that do not need to be tested, leaving only the test layer to be tested. The test layer is a single fiber layer or at least two interlayer fiber layers.

[0011] During the peeling process, care should be taken to minimize damage to the detection layer to avoid distortion of the detection data;

[0012] Step S2: Test the bonding strength of the pretreated test layer using an interlayer bonding strength tester.

[0013] S2.1 Adjust the leveling feet of the interlayer bond strength tester and check the level on the base to ensure the machine is level;

[0014] S2.2 pointer returns to zero

[0015] S2.2.1 Raise the impact rod and fix it to the fixed hook;

[0016] S2.2.2 Move the pointer until it contacts the lever;

[0017] S2.2.3 Press down the fixing hook to let the impact hammer fall freely, and visually check whether the pointer is at the zero point on the dial.

[0018] S2.2.4 If the pointer exceeds or fails to reach the zero point on the dial, adjust the screw until the pointer returns to zero;

[0019] S2.3 Install the test layer sample;

[0020] S2.3.1 Take a roll of double-sided tape with a width of 25.4 mm and fix it on the double-sided tape holder of the interlayer bond strength tester;

[0021] S2.3.2 Cut the paper sample to be tested into strips of 25.4mm×127mm for later use, and place the five sample holders on the clamping seat pins of the interlayer bond strength tester;

[0022] S2.3.3 Take double-sided tape from the double-sided tape fixing stand and stick it on the sample holder;

[0023] S2.3.4 Adhere the 25.4mm×127mm test sample to the double-sided adhesive on the sample holder;

[0024] S2.3.5 Next, from the double-sided tape fixing stand, pull out a layer of double-sided tape and stick it to the sample of each test layer, and use a paper cutter to cut along the gap of the sample holder to divide it into five independent 25.4mm×25.4mm squares;

[0025] S2.3.6 Insert the five L-shaped aluminum blocks into the clamping plates on the clamping plate to fix the five L-shaped aluminum blocks together on the clamping plate, and then install the clamping plate on the clamping seat rod;

[0026] S2.3.7 Tighten the two fixing nuts on the left and right sides to fix the clamping plate on the clamping seat;

[0027] S2.3.8 Press the clamping rod down, then release the clamping rod upward;

[0028] S2.3.9 Loosen the two retaining nuts on the left and right sides;

[0029] S2.4.1 Press down on the clamping plate, remove the clamping plate, and use a blade to cut the test layer samples on the five sets of sample holders respectively;

[0030] S2.4.2 Place the sample holder on the test stand and adjust the fixing bolts to fix the test on the test stand;

[0031] S2.4.3 Click the test button to read the bonding force value, calculate the average value of five values ​​as a group, and record the bonding force value of the corresponding test layer;

[0032] Step S3: Repeat step S2 to test the bonding strength of the paper samples of different layers of the paper, obtain the bonding strength data of different test layers, obtain the bonding strength and layering position of the corresponding different test layers of the paper, and analyze the current status of the bonding strength of each layer and the existing problems.

[0033] Step S4 involves adjusting the content of additives or the type of fiber in one or more detection layers of the paper, or adjusting the formula and papermaking process of each papermaking layer to increase or decrease the bonding strength between fibers in the corresponding layers. By adjusting the bonding of one detection layer or different multiple detection layers, the overall Z-direction strength of the paper is adjusted, and the bonding strength range of the detection layers or the overall bonding strength range of the paper is obtained to meet the design standards.

[0034] Furthermore, the detection layer is a surface layer, a liner, a core layer, or a bottom layer, wherein the surface layer, liner, core layer, and bottom layer are all single-layer fiber layers; the detection layer may also be a surface layer and liner after peeling off the core layer and bottom layer, a liner and core layer after peeling off the surface layer and bottom layer, a surface layer, liner, and core layer after peeling off the bottom layer, or a core layer and bottom layer after peeling off the surface layer and liner, wherein the surface layer and liner, liner and core layer, surface layer, liner, and core layer, and core layer and bottom layer are all interlayer fiber layers.

[0035] Furthermore, the interlayer bond strength tester is the LD-CJJH-02 interlayer bond tester, which is suitable for testing the interlayer bond of liquid packaging paper, the interlayer bond of yarn tube base paper, the interlayer bond of white cardboard, the interlayer bond of kraft paperboard, and the interlayer bond of linerboard.

[0036] The beneficial effects of this invention are:

[0037] When testing the entire sheet of paper with existing interlayer bonding strength testers, only the data between the two layers with the weakest fiber bonding strength in multi-layer papermaking can be detected. This is only a simple qualitative analysis of the fiber bonding strength in multi-layer papermaking, resulting in low precision in subsequent adjustment and control, and the control results may not be completely accurate.

[0038] This invention peels off different fiber layers of paper, leaving corresponding target detection layers, and determines the bonding strength between each fiber layer. It then obtains the bonding force between different layers of the paper and their delamination positions. Through quantitative analysis, it can accurately and effectively detect the interlayer bonding force of printed paper in a short time, with low cost and high efficiency.

[0039] Then, based on the data of the detected layer bonding strength, the bonding between different fiber layers can be explained more clearly. The content of additives or the type of fiber in one or more layers of different test layers in the finished paper can be adjusted, or the formula and papermaking process of each papermaking layer can be adjusted to finely adjust the bonding strength of the paper. This allows for targeted control of the direction of internal stress release when the paper is affected by external forces during processing, thereby reducing the risk of paper breakage. [Attached Image Description]

[0040] Figure 1 This is a schematic diagram of the layer distribution structure of the liquid packaging paper in an embodiment of the present invention.

Detailed Implementation Methods

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] A method for controlling interlayer bonding strength in paper, used for single-layer and interlayer testing and bonding strength regulation in multi-layer liquid packaging paper, includes the following steps:

[0043] Step S1, Preprocessing

[0044] The multi-layered liquid packaging paper undergoes pretreatment by manually peeling off the fiber layers that do not require testing, leaving only the test layer. This test layer consists of a single fiber layer and at least two interlayer fiber layers. In this embodiment, as shown... Figure 1 As shown, the detection layers of the liquid packaging paper are surface layer 1, liner layer 2, core layer 3, and bottom layer 4, all of which are single-layer fiber layers. The detection layers of the liquid packaging paper also include surface layer 1 and liner layer 2 (surface layer + liner layer) after peeling off core layer 3 and bottom layer 4, liner layer 2 and core layer 3 (liner layer + core layer) after peeling off surface layer 1 and bottom layer 4, surface layer 1, liner layer 2 and core layer 3 (surface layer + core layer) after peeling off bottom layer 4, and core layer 3 and bottom layer 4 (core layer + bottom layer) after peeling off surface layer 1 and liner layer 2, liner layer 2 and core layer 3, surface layer 1, liner layer 2 and core layer 3, and core layer 3 and bottom layer 4, all of which are interlayer fiber layers.

[0045] Furthermore, during the peeling process, care should be taken to minimize damage to the detection layer to avoid distortion of the detection data;

[0046] Step S2 involves testing the bonding strength of the pretreated test layers using an interlayer bonding strength tester. This allows for the directional determination of the interlayer bonding strength of each test layer (excluding the weakest fiber layer). The interlayer bonding strength tester used is the LD-CJJH-02 interlayer bonding tester, and the specific testing steps are as follows:

[0047] S2.1 Adjust the leveling feet of the interlayer bond strength tester and check the level on the base to ensure the machine is level;

[0048] S2.2 pointer returns to zero

[0049] S2.2.1 Raise the impact rod and fix it to the fixed hook;

[0050] S2.2.2 Move the pointer until it contacts the lever;

[0051] S2.2.3 Press down the fixing hook to let the impact hammer fall freely, and visually check whether the pointer is at the zero point on the dial.

[0052] S2.2.4 If the pointer exceeds or fails to reach the zero point on the dial, adjust the screw until the pointer returns to zero;

[0053] S2.3 Install the test layer sample;

[0054] S2.3.1 Take a roll of double-sided tape with a width of 25.4 mm and fix it on the double-sided tape holder of the interlayer bond strength tester;

[0055] S2.3.2 Cut the paper sample to be tested into strips of 25.4mm×127mm for later use, and place the five sample holders on the clamping seat pins of the interlayer bond strength tester;

[0056] S2.3.3 Take double-sided tape from the double-sided tape fixing stand and stick it on the sample holder;

[0057] S2.3.4 Adhere the 25.4mm×127mm test sample to the double-sided adhesive on the sample holder;

[0058] S2.3.5 Next, from the double-sided tape fixing stand, pull out a layer of double-sided tape and stick it to the sample of the test layer, and use a paper cutter to cut along the gap of the sample holder to divide it into five independent 25.4mm×25.4mm squares;

[0059] S2.3.6 Insert the five L-shaped aluminum blocks into the clamping plates on the clamping plate to fix the five L-shaped aluminum blocks together on the clamping plate, and then install the clamping plate on the clamping seat rod;

[0060] S2.3.7 Tighten the two fixing nuts on the left and right sides to fix the clamping plate on the clamping seat;

[0061] S2.3.8 Press the clamping rod down, then release the clamping rod upward;

[0062] S2.3.9 Loosen the two retaining nuts on the left and right sides;

[0063] S2.4.1 Press down on the clamping plate, remove the clamping plate, and use a blade to cut the test layer samples on the five sets of sample holders respectively;

[0064] S2.4.2 Place the sample holder on the test stand and adjust the fixing bolts to fix the test on the test stand;

[0065] S2.4.3 Click the test button to read the bonding force value, calculate the average value of five values ​​as a group, and record the bonding force value of the corresponding test layer;

[0066] Step S3: Repeat step S2 to test the bonding strength of the test layer paper samples with different layers of paper, and obtain the bonding strength data of different test layers (see Table 1 below). The bonding strength and layering position of the corresponding test layers of paper are obtained, and the current bonding strength and existing problems of each layer are analyzed.

[0067] Step S4 involves adjusting one or more layers of different detection layers in the paper, changing the pulp ratio and the amount of additives added to each layer, reducing core dissociation, and increasing or decreasing the bonding strength between fibers in the corresponding layers. By adjusting the bonding of one detection layer or different multiple detection layers, the overall Z-direction strength of the paper is adjusted, and the bonding strength range of the detection layers or the overall bonding strength range of the paper that meets the design standards is obtained.

[0068] In this embodiment, for liquid packaging paper, in order to reduce the leakage rate during filling, it is required that the internal core layer of the liquid packaging paper separates itself when folded, so as to relieve internal stress without tearing the surface layer and the bottom layer. In the early stage of adjusting the internal bonding force, according to the above steps S1 and S2, the layer bonding force of the liquid packaging paper is tested by using the LD-CJJH-02 interlayer bonding tester. The layers of the liquid packaging paper are peeled off (surface layer + core layer, core layer, core layer + bottom layer), and the bonding force of the three different layers of paper samples is tested. The data obtained are compared with the corresponding paper bonding force and the layering position to analyze the current status of the bonding strength of each layer and the existing problems, so as to carry out targeted adjustment.

[0069] The delamination bonding strength values ​​and delamination characteristics (sites) of different test layers of liquid packaging paper of different varieties and weights are shown in Table 1 below:

[0070] Table 1

[0071]

[0072]

[0073] like Figure 1 As shown in Table 1, the bonding strength of the face liner and core layer (face liner + core layer), single core layer, and core layer and bottom layer (core layer + bottom layer) of the corresponding paper products of the liquid packaging paper were tested respectively. According to the data results, the bonding strength was found to be: single core layer > face liner and core > core layer and bottom layer. Then, based on the test results, the pulp ratio of each layer and the amount of additives and auxiliary materials were changed to reduce the core dissociation, so that the bonding strength of the packaging paper was changed to face liner and core > core layer and bottom layer > core layer. The whole paper showed that the core layer was separated in the interlayer bonding strength tester and was respectively adhered to the bottom layer and face liner.

[0074] Based on the above implementation steps and the data in Table 1, the interlayer bonding strength of liquid packaging paper of different varieties and weights was tested and statistically analyzed. Through quantitative analysis, the ranking pattern of interlayer bonding strength corresponding to different test layers was found. By comparing the correlation between interlayer bonding strength and Z-axis strength, the core layer interlayer bonding strength data was compared and analyzed with the Z-axis data. According to the paper processing requirements, the pulp ratio of each layer and the amount of additives and auxiliary materials were adjusted, and the process of each layer was adjusted accordingly to adjust the layering position. The core layer bonding strength range that meets customer standards was obtained. Stable core layer separation was achieved during the sampling process, thus transforming the difficult-to-control Z-axis strength into relatively easy core layer bonding control. The interlayer bonding strength of printed paper can be accurately detected and controlled in a short time, avoiding paper delamination and paper breakage in liquid packaging paper, and avoiding potential quality problems in the finished paper.

[0075] The various embodiments of the present invention have now been described in detail. To avoid obscuring the concept of this disclosure, some details known in the art have not been described. Those skilled in the art will fully understand how to implement the technical solutions disclosed herein based on the above description.

[0076] The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. All equivalent changes made in accordance with the shape, structure and principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for controlling interlayer bonding force in paper, used for single-layer or interlayer detection in multi-layer papermaking, and for regulating bonding force, characterized in that, Includes the following steps: Step S1, Preprocessing The paper is pre-treated by manually peeling off the fiber layers that do not need to be tested, leaving only the test layer to be tested. The test layer is a single fiber layer or at least two interlayer fiber layers. During the peeling process, care should be taken to minimize damage to the detection layer to avoid distortion of the detection data; Step S2: Test the bonding strength of the pretreated test layer using an interlayer bonding strength tester. S2.1 Adjust the leveling feet of the interlayer bond strength tester and check the level on the base to ensure the machine is level; S2.2 Return the pointer to zero. S2.2.1 Raise the impact rod and fix it to the fixed hook; S2.2.2 Move the pointer until it contacts the lever; S2.2.3 Press down the fixing hook to let the impact hammer fall freely, and visually check whether the pointer is at the zero point on the dial. S2.2.4 If the pointer exceeds or fails to reach the zero point on the dial, adjust the screw until the pointer returns to zero; S2.3 Install the test layer sample; S2.3.1 Take a roll of double-sided tape with a width of 25.4 mm and fix it on the double-sided tape holder of the interlayer bond strength tester; S2.3.2 Cut the paper sample to be tested into strips of 25.4mm×127mm for later use, and place the five sample holders on the clamping seat pins of the interlayer bond strength tester; S2.3.3 Take double-sided tape from the double-sided tape fixing stand and stick it on the sample holder; S2.3.4 Adhere the 25.4mm×127mm test sample to the double-sided adhesive on the sample holder; S2.3.5 Next, from the double-sided tape fixing stand, pull out a layer of double-sided tape and stick it to the sample of each test layer, and use a paper cutter to cut along the gap of the sample holder to divide it into five independent 25.4mm×25.4mm squares; S2.3.6 Insert the five L-shaped aluminum blocks into the clamping plates on the clamping plate to fix the five L-shaped aluminum blocks together on the clamping plate, and then install the clamping plate on the clamping seat rod; S2.3.7 Tighten the two fixing nuts on the left and right sides to fix the clamping plate on the clamping seat; S2.3.8 Press the clamping rod down, then release the clamping rod upward; S2.3.9 Loosen the two retaining nuts on the left and right sides; S2.4.1 Press down on the clamping plate, remove the clamping plate, and use a blade to cut the test layer samples on the five sets of sample holders respectively; S2.4.2 Place the sample holder on the test stand and adjust the fixing bolts to fix the test on the test stand; S2.4.3 Click the test button to read the bonding force value, calculate the average value of five values ​​as a group, and record the bonding force value of the corresponding test layer; Step S3: Repeat step S2 to test the bonding strength of the paper samples of different layers of the paper, obtain the bonding strength data of different test layers, obtain the bonding strength and layering position of the corresponding different test layers of the paper, and analyze the current status of the bonding strength of each layer and the existing problems. Step S4 involves adjusting the content of additives or the type of fiber in one or more detection layers of the paper, or adjusting the formula and papermaking process of each papermaking layer to increase or decrease the bonding strength between fibers in the corresponding layers. By adjusting the bonding of one detection layer or different multiple detection layers, the overall Z-direction strength of the paper is adjusted, and the bonding strength range of the detection layers or the overall bonding strength range of the paper is obtained to meet the design standards.

2. The method for controlling interlayer bonding force in paper according to claim 1, characterized in that, The detection layer is a surface layer, a liner, a core layer, or a bottom layer, wherein the surface layer, liner, core layer, and bottom layer are all single-layer fiber layers; the detection layer may also be a surface layer and liner after peeling off the core layer and bottom layer, a liner and core layer after peeling off the surface layer and bottom layer, a surface layer, liner, and core layer after peeling off the bottom layer, or a core layer and bottom layer after peeling off the surface layer and liner, wherein the surface layer and liner, liner and core layer, surface layer, liner, and core layer, and core layer and bottom layer are all interlayer fiber layers.

3. The method for controlling interlayer bonding force in paper according to claim 1, characterized in that, The interlayer bond strength tester is the LD-CJJH-02 interlayer bond tester, which is suitable for testing the interlayer bond of liquid packaging paper, the interlayer bond of yarn tube base paper, the interlayer bond of white cardboard, the interlayer bond of kraft paperboard, and the interlayer bond of linerboard.

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