Method for evaluating polymer hot-melt welding performance

A hot-melt welding and polymer technology, applied in the direction of analyzing materials, measuring devices, instruments, etc., can solve the problems of alignment degree influence, internal knotting, large welding scars, etc., to reduce the welding defective rate and detect the required materials Less, effective welding performance effect

Inactive Publication Date: 2020-08-28
UNIV OF SCI & TECH OF CHINA +1
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  • Summary
  • Abstract
  • Description
  • Claims
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AI Technical Summary

Problems solved by technology

Take hot plate welding as an example. For plastic joints, hot plate welding is the simplest mass production technology; a high-temperature hot plate is placed between the surfaces to be welded, heated for a period of time, and pulled out after softening. The surface is bonded under pressure and kept for a period of time. After the molten surface cools down, the welding is completed; the temperature of hot plate welding is generally between 180°C and 230°C (for the determination of the temperature range, different materials are different), the specific It is determined according to the thickness and type to be welded; there are many factors that affect the welding quality, including the temperature of the heating plate, heating time, pressurization pressure, pressurization time, the structure of the weldment, and the degree of plasticization of the polymer resin; in addition , the alignment of the mold can also affect the welding quality, and there are defects such as cracks that cannot be welded, large weld scars, and internal knots; these defects increase the defective rate, lead to material loss, and increase the cost
[0004] At present, the existing technology lacks an effective evaluation method to judge the welding quality of a certain formula weldment in advance. It can only be based on the welding results in production: whether the welding joint is firm or not, whether there are welding scars and other intuitive phenomena, and then the workers can determine the welding quality according to their experience. Adjust the welding heating time, temperature and other conditions to improve the welding quality of the weldment
However, the above-mentioned technical scheme has defects such as large material loss and strong dependence on workers' operating experience, which cannot be used as a standard for evaluating welding quality, and does not have generalizability and ease of learning.

Method used

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  • Method for evaluating polymer hot-melt welding performance
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  • Method for evaluating polymer hot-melt welding performance

Examples

Experimental program
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Effect test

preparation example Construction

[0048] The present invention has no special limitation on the preparation method of the polymer pellets, which is obtained by premixing the polymer material with additives (additives are also optional) well known to those skilled in the art, and then granulating through a twin-screw extruder.

[0049] In the present invention, the vacuum lamination device is preferably a vacuum lamination machine, so that the entire vacuum lamination process is kept in a vacuum state; the temperature of the vacuum lamination is preferably 110°C to 180°C, and the melting time is preferably 2min to 3min; the number of times of pressure relief of the vacuum lamination is preferably 3 to 5 times, more preferably 3 to 4 times; the pressure of the vacuum lamination is preferably 8MPa to 12MPa, more preferably 10MPa; The holding time of the vacuum film pressing is preferably 1 min to 2 min.

[0050] After the polymer film is obtained, the present invention prepares samples of the obtained polymer fil...

Embodiment 1

[0062] Heat the PVC plasticizer to 40°C and add it into a high-speed mixer to mix and plasticize it with PVC resin powder, then extrude and granulate through a twin-screw extruder to obtain PVC resin particles.

[0063] Firstly, the PVC resin particles are pressed into a film in a vacuum laminator. The lamination temperature is 160°C, melted for 2 minutes, released 3 times, and kept at 10MPa for 1 minute. The whole process is kept in a vacuum state to obtain a PVC composite film; Then cut the pressed film into rectangular splines with a width of 3 cm, a length of 7 cm, and a thickness of 1.2 mm; then set the temperature of the small open mill to 180 ° C, and preheat the cut rectangular splines on the roller surface respectively 2s, 5s, 10s, 20s and 40s, and then stick the two film samples together, pass through the gap between the two rolls of the open mill, the gap between the two rolls is 1.6mm, complete the welding, and obtain the welded film, which is further cut into Rect...

Embodiment 2

[0067] The following steps evaluate the welding performance of plasticizer 60°C PVC resin particles. The operation process is the same as in Example 1, the difference is that the PVC plasticizer is heated to 60°C and then added to a high-speed mixer to mix with PVC resin powder for plasticization .

[0068] Figure 6 Be the peeling strength-displacement curve of PVC resin particle (plasticizer 60 ℃ sample) different warm-up times among the embodiment 2; When reaching the end of displacement, the spline peels off completely; By Figure 6 It can be seen that when the preheating time increases from 2s to 20s, the peel strength gradually increases from 100N / m to 1600N / m. If the preheating time is continued to be extended to 40s, the peel strength increases very little and reaches a plateau.

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Abstract

The invention provides a method for evaluating polymer hot-melt welding performance, wherein the method comprises the following steps: a) performing vacuum film pressing on polymer granules to obtaina polymer film; b) preparing a sample from the polymer film obtained in the step a), preheating two film sample strips, and carrying out roll-in welding to obtain a welded film; and c) cutting the welded film obtained in the step b) into rectangular sample strips, carrying out a T-shaped stripping test, and evaluating the polymer hot-melt welding performance according to the test result. Comparedwith the prior art, according to the method provided by the invention, the welding performance of the high polymer material can be scientifically and effectively evaluated; furthermore, the operationconditions of actual welding production can be adjusted according to the obtained change curve of the peel strength; the defects that in the prior art, the welding quality can be evaluated and the welding condition can be adjusted only after polymer welding is completed are overcome, so that the welding defective rate of polymer materials is reduced, material losses are reduced, and an important role is played in perfecting the polymer hot-melt welding quality evaluation standard.

Description

technical field [0001] The invention relates to the technical field of polymer materials, and more specifically, relates to a method for evaluating the thermal fusion welding performance of polymers. Background technique [0002] Polymer materials have been widely used in various fields of the national economy, from high-tech aerospace to ordinary people's basic necessities of life, are inseparable from the use of polymer materials. From a material to a product, it needs to go through the forming process of shaping to have actual functions. Due to the influence of material processing technology, many products with complex structures cannot be formed in one step, but are composed of multiple materials or components. Currently, the individual components can be joined using mechanical fasteners, adhesives and welding; of the three joining methods, the welding process works best. [0003] Plastic welding is an effective method for permanently joining plastic parts, and only the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N19/04
CPCG01N19/04
Inventor 王志刚李昆张娟王学会严娟答镇魏锋储贻健
Owner UNIV OF SCI & TECH OF CHINA
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