Method for testing heat resistance of adhesive

Abstract

The invention belongs to the technical field of performance detection, and provides a method for testing the heat resistance of an adhesive. The method comprises the following steps: coating one surface of a base material with an adhesive, drying, folding the base material, bonding one surface of the base material containing the adhesive, applying pressure, heating, measuring the length of the bonded part of the base material, and comparing the length with a standard value. If the length of the bonding maintaining part is larger than or equal to a standard value, the heat resistance of the adhesive is qualified, otherwise, the heat resistance of the adhesive is unqualified, and the standard value is a minimum value which passes an experimental test and meets the requirements of customers or an empirical value accumulated in the production detection process. The method provided by the invention is simple and convenient to operate, can quickly judge the heat resistance of the adhesive or judge whether the adhesive meets the requirements, can simultaneously test a plurality of test pieces, is easier to obtain a plurality of parallel data, reduces accidental errors, and is high in accuracy and high in measurement efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of detection methods, and more specifically, to a test method for the heat resistance of adhesives. Background Art

[0002] Before use, adhesives (such as adhesives for shoe materials) generally need to be tested for heat resistance. For example, the heat resistance test method for general shoe adhesives uses the "creep method" (i.e., "HG / T 2815 1996 Test Method for Heat Resistance of Shoe Adhesives - Creep Method") for testing. The test results can be expressed by the average peel length or the complete peel time. If the specimen is completely peeled within 10 minutes, the complete peel time is recorded. The longer the complete peel time, the better the heat resistance. If the peel length of the specimen within the specified time is recorded, the smaller the peel length, the better the heat resistance. However, the creep method requires the use of a load weight to apply the peel force, so it involves cumbersome manual operations such as punching holes and hanging hooks on the test pieces and the preparatory work before bonding the test pieces. This method is complex in operation, has cumbersome steps, takes a long time, and is difficult to detect a large number of samples simultaneously. It is not suitable for the rapid screening of the quality of adhesives during the development process and the rapid detection in daily production.

[0003] Therefore, there is an urgent need to develop a test method for the heat resistance of adhesives that is simple, fast, and suitable for large-scale batch testing. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. For this purpose, the present invention provides a test method for the heat resistance of adhesives. The test method provided by the present invention does not require the use of weights and does not require operations such as punching holes and hanging hooks on the substrate. It has few steps, can quickly measure and screen out adhesives that meet the heat resistance requirements, is suitable for large-scale batch testing of the heat resistance of adhesives, and can be used in the production and preparation process of adhesives.

[0005] The first aspect of the present invention provides a test method for the heat resistance of adhesives.

[0006] Specifically, a test method for the heat resistance of adhesives includes the following steps:

[0007] Take a substrate and the adhesive to be detected. Coat the adhesive to be detected on one surface of the substrate, then dry it, fold the substrate in half so that the surface with the adhesive on the substrate adheres, then apply pressure, then heat it, and finally measure the length of the adhered part of the substrate. Compare the length of the adhered part of the substrate with the standard value. If the length of the adhered part of the substrate ≥ the standard value, it means that the heat resistance of the adhesive is qualified; otherwise, it means that the heat resistance of the adhesive is unqualified.

[0008] The present invention utilizes the stress (rebound force) generated when the substrate is folded in half to replace the load weight, thus eliminating cumbersome manual operations (such as punching holes in the substrate, hanging hooks, and preparing before bonding the substrate). And by comparing the lengths of the bonded parts of the adhesive sample to be tested and the standard sample, it is determined whether the heat resistance of the adhesive to be tested meets the requirements. The method of the present invention has fewer steps, is easy to operate, and can quickly judge the quality of the heat resistance of the adhesive or determine whether the adhesive meets the requirements.

[0009] Preferably, the standard value is the length of the bonded part of the substrate measured after the standard sample is tested by the same test method. The standard sample is a qualified product tested by the creep method (HG / T 2815 1996 Test Method for Heat Resistance of Adhesives for Shoes - Creep Method). The adhesive to be tested and the standard sample belong to the same type of adhesive and are tested using the same substrate.

[0010] Preferably, the adhesive to be tested and the standard sample are tested using substrates of the same material and size.

[0011] Preferably, the number of adhesives to be tested ≥ 1. The method of the present invention can achieve the simultaneous detection of one or more adhesives, and can also achieve the simultaneous detection of multiple adhesives of the same type.

[0012] Preferably, the adhesive is at least one of polyurethane - type adhesives, chloroprene rubber adhesives, natural rubber adhesives, synthetic elastomer rubber adhesives (such as styrene - butadiene rubber SBS adhesives, styrene - isoprene - styrene block copolymer SIS adhesives).

[0013] Preferably, the substrate is at least one of thermoplastic polyurethane rubber (TPU), polyvinyl chloride (PVC), ethylene - vinyl acetate copolymer (EVA), and vulcanized rubber.

[0014] Preferably, the length, width, and height of the substrate are 10 - 50 mm, 30 - 150 mm, and 1 - 10 mm respectively.

[0015] Further preferably, the length, width, and height of the substrate are 15 - 30 mm, 40 - 130 mm, and 1 - 5 mm respectively.

[0016] More preferably, the length, width, and height of the substrate are 25 - 30 mm, 50 - 120 mm, and 3 - 4 mm respectively.

[0017] Preferably, before the test, the substrate is subjected to dust removal treatment. The dust removal treatment is to wipe the surface with a wet cotton cloth to remove dust, and then placed at room temperature for more than 2 h.

[0018] Preferably, the drying temperature is 50 - 80 °C, and / or the drying time is 1 - 10 min.

[0019] Further preferably, the temperature of the drying is 60 - 75 °C, and / or the time of the drying is 5 - 10 min.

[0020] Preferably, the temperature of the heating is 90 - 110 °C, and / or the time of the heating is 5 - 15 min.

[0021] Further preferably, the temperature of the heating is 95 - 105 °C, and / or the time of the heating is 10 - 13 min.

[0022] During the test process of the present invention, heating is carried out twice successively. The first heating, namely drying, aims to volatilize the solvent in the adhesive. The second heating is for the heat resistance test of the adhesive. In addition, the present invention can adjust the test heating temperature and time to meet the test requirements of different adhesives.

[0023] Preferably, the pressure of the pressing is 30 - 40 MPa, and / or the time of the pressing is 1 - 20 s.

[0024] Further preferably, the pressure of the pressing is 35 - 40 MPa, and / or the time of the pressing is 10 - 20 s.

[0025] Preferably, after the pressing, it is placed at room temperature for 1 - 10 min and then heated.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] In the present invention, a base material and an adhesive to be detected are taken. First, the adhesive is coated on one surface of the base material, then dried, then the base material is folded in half to bond the surface of the base material containing the adhesive, then pressed, then heated, and finally the length of the bonded part of the base material is measured. The length of the bonded part of the base material is compared with the standard value. If the length of the bonded part of the base material ≥ the standard value, it indicates that the heat resistance of the adhesive is qualified; otherwise, it indicates that the heat resistance of the adhesive is unqualified. The present invention uses the stress (rebound force) generated when the base material is folded in half to replace the load weight, thus eliminating the cumbersome manual operations such as punching holes and hanging hooks on the test piece and the preparatory work before bonding the test piece. The operation is more convenient, can quickly judge the heat resistance quality of the adhesive or judge whether the adhesive meets the requirements, can meet the needs of rapid detection and screening in the production process, can also easily realize the simultaneous detection of multiple test pieces, is more likely to obtain multiple parallel data, reduces accidental errors, has high accuracy and high measurement efficiency. Description of the Drawings

[0028] Figure 1 It is a schematic diagram of the operation process of the test method of Embodiment 1 of the present invention;

[0029] Figure 2 Schematic diagram of the samples in steps (1), (3), and (7) of the test method of Embodiment 1 of the present invention;

[0030] Figure 3 Front view of three parallel test samples after heating in Embodiment 2 of the present invention;

[0031] Figure 4 Side view of three parallel test samples after heating in Embodiment 2 of the present invention;

[0032] Figure 5 Operating diagram of the creep method of Comparative Example 1. Detailed implementation manners

[0033] In order to make those skilled in the art more clearly understand the technical solutions described in the present invention, the following embodiments are listed for illustration. It should be noted that the following embodiments do not limit the protection scope required by the present invention.

[0034] In the following embodiments, the raw materials, reagents or devices used can be obtained from conventional commercial channels or can be obtained by existing known methods without special instructions.

[0035] The main raw materials used in the present invention:

[0036] Substrate to be detected: TPU soft board, with models of 4mm and 3mm, produced by Guangzhou Yongsheng Plastics Co., Ltd.

[0037] Substrate to be detected: vulcanized rubber sheet, with a model of 3mm, produced by Japan NOTAPE Co., Ltd.

[0038] Adhesives: produced by Zhuhai Zetao Adhesive Products Co., Ltd., with models of U-248FM (LOT1), U-248FM (LOT2), U-261FH (LOT3), U-261FH (LOT4), C-033FJ, and C-237FK...

[0039] Embodiment 1

[0040] A test method for the heat resistance of a polyurethane adhesive 1 (as shown in Figure 1 ) includes the following steps:

[0041] (1) First, take a TPU soft board as the substrate, cut it into multiple test pieces of the same size (the length and width are denoted as L0 and h respectively, as shown in Figure 2 A), then clean and wipe the surface with a wet cotton cloth to remove dust; place it at room temperature for more than 2 hours, and use a brush to evenly apply polyurethane adhesive 1 on the TPU sheet (i.e., brush glue);

[0042] (2) Place it in a 60 °C circulating oven for 6 min for drying;

[0043] (3) Then fold the substrate in half and bond the head and tail. The folded substrate includes an open end and a closed end, and the initial bonded part has a length of L1 (as shown in Figure 2 B);

[0044] (4) Place it in the flat press fixture, apply a pressure of 35 MPa, and press for 12 s;

[0045] (5) After pressing, take out the substrate and place it at room temperature for 5 min;

[0046] (6) Put it into a 105 °C circulating oven and bake for 10 min for heating, then take it out. After taking it out, as shown in Figure 3 and Figure 4 , the open end remains bonded, while the closed end side opens due to insufficient heat resistance of the adhesive;

[0047] (7) Use a ruler to measure the length of the bonded part of the substrate, which is L2 (as shown in Figure 2 C).

[0048] Example 2 - 4

[0049] The test method for the heat resistance of the adhesive in Example 2 - 4 is different from that in Example 1 in that polyurethane adhesive 1 is replaced with polyurethane adhesives 2 - 4 respectively, and the test conditions are changed. The specific test conditions are shown in Table 1.

[0050] Example 5 - 6

[0051] The test method for the heat resistance of the adhesive in Example 5 - 6 is different from that in Example 1 in that polyurethane adhesive 1 is replaced with chloroprene adhesives 1 - 2 respectively, and the test conditions are changed. The specific test conditions are shown in Table 1.

[0052] Comparative Example 1

[0053] The test method for the heat resistance of polyurethane adhesive 1 specifically refers to the traditional creep method in "HG / T 2815 1996 Test Method for Heat Resistance of Shoe Adhesives - Creep Method". Some operating parameters are shown in Table 2, and the steps are as follows:

[0054] (1) Separate the unbonded parts of the specimen, and use a ballpoint pen to draw a horizontal marking line at the starting bonding position of the harder adherend;

[0055] (2) When the temperature of the test chamber reaches the experimental temperature of 80 °C, place three parallel specimens into the test chamber; connect the harder adherend to the upper fixture, and connect the softer adherend to the lower fixture; hang a weight on the hook of the lower fixture; make the bonded part of the specimen bear a load of 1 kg, as shown in Figure 5 ;

[0056] (3) Start timing when closing the box. Conduct the heat preservation test for 24 h. Open the test box and draw a horizontal marking line with a ballpoint pen at the peeling position of the harder adherend of the specimen.

[0057] (4) Remove the weights, then take out the specimen from the test box and measure the distance between the two marking lines, accurate to 1 mm.

[0058] Comparative Example 2-4

[0059] Adopt the same method as in Comparative Example 1 to test the heat resistance of polyurethane adhesives 2-4 respectively, and change the test conditions. The specific test conditions are shown in Table 1.

[0060] Comparative Example 5-6

[0061] Adopt the same method as in Comparative Example 1 to test the heat resistance of chloroprene adhesives 1-2 respectively, and change the test conditions. The specific test conditions are shown in Table 1.

[0062] The test conditions and test results of Examples 1-6 and Comparative Examples 1-6 are shown in the following table.

[0063] Table 1 Test methods, test conditions and test results of each example

[0064]

[0065] Table 2 Test methods, test conditions and test results of each comparative example

[0066]

[0067]

[0068] As can be seen from the above table, polyurethane adhesive 1 showed a large degree of opening after being heated at 105 °C for 10 min, so its heat resistance was unqualified; while the heat resistance of polyurethane adhesive 2 was qualified, and it could withstand heating at 105 °C for at least 10 min and maintain good adhesion; polyurethane adhesive 3 could not maintain good adhesion after being heated at 70 °C for 10 min, and the heat resistance test was unqualified; polyurethane adhesive 4 could withstand heating at 70 °C for at least 10 min; the heat resistance test of chloroprene rubber adhesive 1 was unqualified after being heated at 70 °C for 10 min; the heat resistance test of chloroprene rubber adhesive 2 was qualified after being heated at 70 °C for 10 min.

[0069] In addition, the test results of the heat resistance of the adhesives of the present invention are completely consistent with the test results of the creep method, indicating that the test method of the present invention has high accuracy, and compared with the creep method, it has fewer operation steps, is simple and easy to operate, shortens the detection time, can detect multiple adhesive samples of the same kind or different kinds at the same time, and improves the detection efficiency while ensuring the accuracy of the detection.

Claims

1. A method for testing heat resistance of an adhesive, characterized in that: The steps include: Take a substrate and an adhesive to be tested, apply the adhesive to be tested on one surface of the substrate, then dry it, fold the substrate in half so that the side of the substrate containing the adhesive is bonded, then apply pressure, and heat it. Finally, measure the length of the adhesive portion of the substrate, and compare the length of the adhesive portion of the substrate with a standard value. If the length of the adhesive portion of the substrate is ≥ the standard value, it means that the heat resistance of the adhesive is qualified; otherwise, it means that the heat resistance of the adhesive is unqualified.

2. The testing method according to claim 1, characterized in that: The adhesive is at least one of a polyurethane adhesive, a chloroprene rubber adhesive, a natural rubber adhesive, and a synthetic elastomer rubber adhesive.

3. The testing method according to claim 1, characterized in that: The substrate is at least one of thermoplastic polyurethane rubber, polyvinyl chloride, ethylene-vinyl acetate copolymer, and vulcanized rubber.

4. The testing method according to claim 1, characterized in that: The length, width and height of the substrate are 10-50 mm, 30-150 mm and 1-10 mm respectively.

5. The testing method according to claim 1, characterized in that: The drying temperature is 50-80° C., and / or the drying time is 1-10 min.

6. The testing method according to claim 5, characterized in that: The drying temperature is 60-75° C., and / or the drying time is 5-10 min.

7. The testing method according to claim 1, characterized in that: The heating temperature is 90-110° C., and / or the heating time is 5-15 min.

8. The testing method according to claim 7, characterized in that: The heating temperature is 95-105° C., and / or the heating time is 10-13 min.

9. The testing method according to claim 1, characterized in that: The pressure of the pressurizing is 30-40 MPa, and / or the time of the pressurizing is 1-20 s.

10. The testing method according to claim 1, characterized in that: After the pressurization, the mixture is placed at room temperature for 1-10 minutes and then heated.

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