A method for testing the heat resistance of an adhesive

Abstract

The present application belongs to the technical field of performance detection, and provides a testing method for heat resistance of an adhesive. The method comprises the following steps: coating the adhesive on one surface of a substrate, drying, folding the substrate, adhering the surface of the substrate containing the adhesive, pressing, heating, measuring the length of the adhered part of the substrate, and comparing the length with a standard value. If the length of the adhered part of the substrate is greater than or equal to the standard value, the heat resistance of the adhesive is qualified; otherwise, the heat resistance of the adhesive is unqualified. The standard value is the minimum value meeting the customer's requirements or the accumulated experience value in the production detection process. The method is simple to operate, can quickly judge the heat resistance of the adhesive or whether the adhesive meets the requirements, can test multiple test pieces at the same time, is easier to obtain multiple parallel data, reduces accidental errors, is high in accuracy, and is high in measurement efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of detection methods, and more particularly to a testing method for heat resistance of adhesives. BACKGROUND

[0002] Before use, adhesives (such as adhesives for shoe materials) generally need to be tested for heat resistance. For example, the testing method for heat resistance of general shoe adhesives adopts a "creep method" (i.e., HG / T 2815 1996 Test Method for Heat Resistance of Shoe Adhesives-Creep Method) for testing. The test result can be represented by the average peeling length or the complete peeling time. If the test sample is completely peeled off within 10 minutes, the complete peeling time is recorded. The longer the complete peeling time, the better the heat resistance. If the peeling length of the test sample within the specified time is recorded, the smaller the peeling length, the better the heat resistance. However, the creep method requires the use of a weight to apply a peeling force, and thus involves tedious manual operations such as punching of test pieces, hooking, and preparation work before the test pieces are attached. This method is complicated to operate, has tedious steps, and takes a long time, and it is difficult to simultaneously test a large number of samples. Therefore, it is not suitable for rapid screening of adhesive quality during the development process and rapid detection in daily production.

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

[0004] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application provides a testing method for heat resistance of adhesives. The testing method provided by the present application does not require the use of a weight, and does not require punching, hooking, or other operations on the substrate. The steps are few, and the adhesives that meet the heat resistance requirements can be quickly measured and screened. The testing method is suitable for large-scale batch testing of heat resistance of adhesives, and can be used in the production and preparation process of adhesives.

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

[0006] Specifically, the testing method for heat resistance of adhesives comprises the following steps:

[0007] The substrate and the adhesive to be detected are taken, the adhesive to be detected is coated on one surface of the substrate, then dried, the substrate is folded so that the surface containing the adhesive is adhered, then pressed, heated, and finally the length of the adhered part of the substrate is measured. The length of the adhered part of the substrate is compared with a standard value. If the length of the adhered part of the substrate is greater than or equal to 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.

[0008] The present application uses the stress (rebound force) generated when the substrate is folded to replace the weight load, thereby eliminating the cumbersome manual operation (such as substrate punching, hook hanging, and preparation before sticking the substrate, etc.). The heat resistance of the adhesive to be tested is determined by comparing the length of the adhesive part to be tested with the length of the adhesive part to be tested with the standard sample. The method of the present application has fewer steps, is simple to operate, and can quickly determine the heat resistance of the adhesive or whether the adhesive meets the requirements.

[0009] Preferably, the standard value is the length of the substrate adhesive part measured after the standard sample is tested using the same test method. The standard sample is a qualified product tested by the creep method (HG / T 2815 1996 Shoe Adhesive Heat Resistance Test Method 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 the same material and size of substrate.

[0011] Preferably, the number of adhesives to be tested is ≥1. The method of the present application can simultaneously detect one or more adhesives, or can simultaneously detect multiple adhesives of the same type.

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

[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 10-50mm, 30-150mm, and 1-10mm, respectively.

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

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

[0017] Preferably, the substrate is dusted before testing, and the dusting treatment is to wipe the surface with a wet cotton cloth to remove dust, and then place it at room temperature for more than 2h.

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

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

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

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

[0022] In the testing process of the present application, two heating processes are performed successively, the first heating process is drying, which aims to evaporate the solvent in the adhesive, and the second heating process is for testing the heat resistance of the adhesive. In addition, the testing heating temperature and time can be adjusted to adapt to the testing 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, the sample is placed at room temperature for 1-10 min, and then heated.

[0026] Compared with the prior art, the present application has the following advantages:

[0027] In the present application, the adhesive is coated on one surface of the substrate, and then dried, and then the substrate is folded to make the surface containing the adhesive adhere, and then pressed, and then heated, and finally the length of the adhered part of the substrate is measured, and compared with the standard value, if the length of the adhered part of the substrate is greater than or equal to 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 application uses the stress (rebound force) generated when the substrate is folded instead of the dead weight, thereby eliminating the tedious manual operation work such as punching and hooking of the test piece, and the preparation work before the test piece is adhered, the operation is more simple, the heat resistance of the adhesive can be quickly judged, and whether the adhesive meets the requirements can be quickly judged, which can meet the demand for rapid detection and screening in the production process, and multiple test pieces can be easily detected at the same time, it is easier to obtain multiple parallel data, reduces accidental errors, has high accuracy, and has high measurement efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The operation flowchart of the testing method of Example 1 of the present application is shown in the figure;

[0029] Figure 2 A schematic diagram of the sample for step (1), (3), (7) of the test method of Example 1 of the present application;

[0030] Figure 3 A front view of the three parallel test samples after heating of Example 2 of the present application;

[0031] Figure 4 A side view of the three parallel test samples after heating of Example 2 of the present application;

[0032] Figure 5 An operation diagram of the creep method of Comparative Example 1. DETAILED DESCRIPTION

[0033] In order to make the skilled in the art more clearly understand the technical solutions described in the present application, the following examples are listed for illustration. It should be pointed out that the following examples do not constitute a limitation on the scope of protection required by the present application.

[0034] The raw materials, reagents or devices used in the following examples, unless otherwise specified, can be obtained from conventional commercial channels, or can be obtained by existing known methods.

[0035] The main raw materials used in the present application are as follows:

[0036] The substrate to be tested: TPU soft plate, model 4mm, 3mm, produced by Guangzhou Yongsheng Plastic Co., Ltd.

[0037] The substrate to be tested: vulcanized rubber sheet, model 3mm, produced by Japan NOTAPE Co., Ltd.

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

[0039] Example 1

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

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

[0042] (2) Place in a circulating oven at 60°C for 6 min to dry;

[0043] (3) Then fold the base sheet in half and bond it together. The folded base sheet includes an open end and a closed end. The length of the initial bonded portion is L1 (e.g. Figure 2 B);

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

[0045] (5) After lamination, remove the substrate and place it at room temperature for 5 minutes;

[0046] (6) Place in a 105°C circulating oven for 10 minutes to heat, then take out. Figure 3 and Figure 4 As shown, the open end remains bonded, while one side of the closed end opens due to insufficient heat resistance of the adhesive;

[0047] (7) Use a ruler to measure the length of the substrate holding the bonding portion, which is L2 (e.g. Figure 2 C).

[0048] Examples 2-4

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

[0050] Examples 5-6

[0051] The test method for the heat resistance of the adhesives of Examples 5-6 differs from that of Example 1 in that the polyurethane adhesive 1 is replaced by 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 heat resistance test method 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 include the following:

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

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

[0056] (3) Start timing when the oven is closed, and keep the sample in the oven for 24 hours. Then open the oven and draw another horizontal mark line on the sample with a ballpoint pen at the peeling position of the harder adherend.

[0057] (4) Remove the weights, and then take out the sample from the oven. Measure the distance between the two mark lines with an accuracy of 1 mm.

[0058] Comparative Example 2-4

[0059] The heat resistance of polyurethane adhesive 2-4 was tested by the same method as Comparative Example 1, and the test conditions were changed, as shown in Table 1.

[0060] Comparative Example 5-6

[0061] The heat resistance of neoprene adhesive 1-2 was tested by the same method as Comparative Example 1, and the test conditions were changed, as 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 method, test conditions and test results of each example

[0064]

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

[0066]

[0067]

[0068] As can be seen from the above table, polyurethane adhesive 1 is opened to a large extent after heating at 105℃ for 10 min, so its heat resistance is unqualified; the heat resistance of polyurethane adhesive 2 is qualified, which can withstand heating at 105℃ for at least 10 min and maintain good adhesion; polyurethane adhesive 3 cannot maintain good adhesion after heating at 70℃ for 10 min, and the heat resistance test is unqualified; polyurethane adhesive 4 can withstand heating at 70℃ for at least 10 min; the heat resistance test of neoprene adhesive 1 at 70℃ for 10 min is unqualified; the heat resistance test of neoprene adhesive 2 at 70℃ for 10 min is qualified.

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

Claims

1. A method of testing heat resistance of an adhesive, characterized by, The method comprises the following steps: The method comprises the following steps: taking a substrate and an adhesive to be detected, coating the adhesive to be detected on one surface of the substrate, drying, folding the substrate, adhering the surface of the substrate containing the adhesive, pressing, heating, and measuring the length of the adhesive part of the substrate, and comparing the length of the adhesive part of the substrate with a standard value, wherein the length of the adhesive part of the substrate greater than or equal to the standard value indicates that the heat resistance of the adhesive is qualified, otherwise, the heat resistance of the adhesive is unqualified.

2. The test method of claim 1, wherein, The adhesive is at least one of polyurethane type adhesive, chloroprene rubber type adhesive, natural rubber type adhesive, and synthetic elastomer rubber adhesive.

3. The test method of claim 1, wherein, The substrate is at least one of thermoplastic polyurethane rubber, polyvinyl chloride, ethylene-vinyl acetate copolymer, and vulcanized rubber.

4. The test method of claim 1, wherein, The length, width, and height of the substrate are 10-50 mm, 30-150 mm, and 1-10 mm, respectively.

5. The test method of claim 1, wherein, The drying temperature is 50-80 ℃, 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 ℃, and / or the drying time is 5-10 min.

7. The test method of claim 1, wherein, The heating temperature is 90-110 ℃, and / or the heating time is 5-15 min.

8. The test method of claim 7, wherein, The heating temperature is 95-105 ℃, and / or the heating time is 10-13 min.

9. The test method of claim 1, wherein, The pressure of the pressing is 30-40 MPa, and / or the pressing time is 1-20 s.

10. The test method of claim 1, wherein, The substrate is placed at room temperature for 1-10 min after the pressing, and then heated.

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