Leakage detection glue solution for vacuum forming mold and leakage point detection method

Abstract

The invention relates to a leak detection glue solution for a vacuum forming mold and a leak point detection method. The leak detection glue solution comprises the following components in parts by mass: 100 parts of water, 4.5-5.5 parts of polyvinyl alcohol, 30-40 parts of an ethanol water solution, 2-8 parts of glycerol, 0.1-0.2 part of tributyl phosphate and 1-2 parts of water-based color paste. According to the leakage point detection method, the surface of a mold is sealed by adopting a vacuum bag film and the like and then is guided, a leakage detection glue solution flows on the surface of the mold at a proper flow speed and leakage detection is carried out, the mold is converted from airtightness detection to liquid airtightness detection, and when a leakage point exists, continuous bubbles can be visually seen from the leakage point, and the leakage point can be rapidly judged; and meanwhile, through operation modes of step-by-step feeding and discharging, reverse feeding and discharging and the like, interference of a certain leakage point on subsequent leakage point detection can be avoided. The leak detection glue solution is moderate in viscosity, can well guide flow during vacuum flow guide, cannot cause difficulty in observation due to too fast flow guide, can be suitable for vacuum flow guide leak detection, can quickly form a glue film when exposed in air, can be directly torn off, and is high in operation efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of vacuum forming processes, and particularly relates to a leak detection glue solution for a mold used in vacuum forming and a method for detecting leak points. Background Art

[0002] The vacuum forming process is widely used and its technology is becoming increasingly mature. Apart from process design, poor mold sealing and local leakage are one of the biggest risk sources in this process currently.

[0003] Especially when there is a leak point in a mold for large-sized special-shaped complex-structured parts, if the specific position of the leak point is not found, leak plugging and repair cannot be carried out, and vacuum forming production and manufacturing work cannot be carried out, which may lead to the direct scrapping of the entire mold, causing irreparable losses to both cost and construction period. After accurately finding the specific leak point, sealing and repair treatment can be carried out. When there is a leak point in a vacuum forming mold, a method for quickly detecting the leak point is extremely important.

[0004] In the prior art, usually after the mold is sealed with a vacuum bag film and a sealing strip, the mold is evacuated to check whether its pressure drops to determine whether it leaks. However, when it is detected that there is a leak, even with a special vacuum leak detector, the specific position of the tiny leak point cannot be found, and only by dividing it into multiple small areas and reducing the detection range method can be used for repeated detection. Even if a large amount of time is consumed to narrow down the leak point range, the specific position of the leak point cannot be directly confirmed. At the same time, since the vacuum bag film itself may also have a puncture leak, when gradually narrowing down the range for leak detection, misjudgment may occur, resulting in great uncertainty and difficulty in leak detection and finding tiny leak points for large-sized products. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a leak detection glue solution for a mold used in vacuum forming and a method for detecting leak points in view of the deficiencies existing in the above-mentioned prior art. The leak detection glue solution is formulated to a certain viscosity, and after being sealed with a vacuum bag film etc. on the mold surface and diverted, it flows on the mold surface at an appropriate flow rate for leak detection. The mold is converted from airtightness inspection to liquid tightness inspection. When there is a leak point, continuous bubbles can be directly seen continuously emerging at the leak point, quickly determining the leak point; at the same time, through operation methods such as step-by-step feeding and reverse feeding, the interference of one leak point on subsequent leak point detection can be avoided; at the same time, the main component of the leak detection glue solution is water, with low cost, and when exposed to air, it can quickly form a glue film and can be directly torn off, with high operation efficiency and simple operation.

[0006] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0007] A leak detection glue solution for a vacuum forming mold, the leak detection glue solution includes by mass: 100 parts of water, 4.5 - 5.5 parts of polyvinyl alcohol, 30 - 40 parts of ethanol aqueous solution, 2 - 8 parts of glycerol, 0.1 - 0.2 parts of tributyl phosphate, and 1 - 2 parts of aqueous color paste.

[0008] In the above solution, the molecular weight of the polyvinyl alcohol is 50000 - 120000 g / mol.

[0009] In the above solution, the ethanol concentration in the ethanol aqueous solution is 90% - 96%.

[0010] In the above solution, the aqueous color paste includes by mass: 30 - 50 parts of aqueous resin, 15 - 30 parts of organic pigment, 20 - 40 parts of water, 1 - 3 parts of thickener, and 3 - 6 parts of dispersant.

[0011] In the above solution, the aqueous resin uses acrylic emulsion; the organic pigment uses zinc titanium red or phthalocyanine blue or iron oxide yellow; the thickener uses urethane; the dispersant uses sodium lignosulfonate.

[0012] In the above solution, the leak detection glue solution is prepared by the following method:

[0013] When heating 100 parts of water to above 90 °C, add 4.5 - 5.5 parts of polyvinyl alcohol, and continuously stir until completely dissolved;

[0014] Let it stand, and naturally cool down to 70 °C - 78 °C, slowly drip 30 - 40 parts of ethanol aqueous solution and continuously stir at a speed of 500 - 1000 r / min;

[0015] Then add 2 - 8 parts of glycerol, 1 - 2 parts of aqueous color paste, and 0.1 - 0.2 parts of tributyl phosphate in sequence, and stir and disperse evenly.

[0016] Correspondingly, the present invention also proposes a method for detecting leak points of a vacuum forming mold, including the following steps:

[0017] S1. Prepare the above leak detection glue solution in advance and perform defoaming treatment;

[0018] S2. On the surface of the mold, lay 1 layer of diversion net, cover a vacuum bag film on the surface of the diversion net, seal the periphery of the vacuum bag film with sealing clay, install the original feed pipe and the original discharge pipe at both ends of the vacuum bag film respectively, and then install a number of relay feed pipes between the original feed pipe and the original discharge pipe;

[0019] S3. Connect the original discharge pipe to the negative pressure device and suck it to -0.1~-0.08MPa negative pressure. Clamp all relay feed pipes. Inhale the leak detection glue liquid at the original feed pipe. The leak detection glue liquid enters from the end of the original feed pipe, infiltrates and guides it to exceed the first relay feed pipe. Check whether there is a mold leakage point in the area between the original feed pipe and the first relay feed pipe. If there is no leakage point, continue to feed from the original feed pipe and check the next interval. If there is an obvious mold leakage point, make a leak detection. The point mark is recorded, and the leak detection glue liquid is changed to enter the next relay feed pipe of the leakage point. The original feed pipe end is changed to the discharge pipe end. In this way, the leak detection glue liquid enters from the first relay feed pipe and flows toward the original feed pipe end and the original discharge pipe end respectively. On the one hand, the bubbles formed between the original feed pipe end and the first relay feed pipe will be drawn to the original feed pipe end to avoid interference with the leak detection of the next section. On the other hand, the leak detection glue liquid continues to infiltrate toward the original discharge pipe end to continue to test the sealing of the mold in the next section.

[0020] S4. Repeat this process until all intervals are leak-checked.

[0021] In the above method, in step S1, the degassing method is: use vacuum degassing equipment to degas the leak detection glue at -0.098 to -0.1 MPa for 3-5 minutes to eliminate the bubbles and set it aside for use to avoid small bubbles in the leak detection glue interfering with subsequent detection.

[0022] In the above method, the original feed pipe, the original discharge pipe and the relay feed pipe are arranged in parallel with a span of 600-1000 mm; a tee joint is installed in the middle of the original feed pipe, the original discharge pipe and the relay feed pipe.

[0023] In the above method, in step S3, the basis for determining the mold leakage point is: when bubbles continuously rise from the bottom, the source of the rising bubbles is the mold leakage point; the method for marking the leakage point is: using a marker pen to mark the corresponding position on the surface of the vacuum bag film.

[0024] The beneficial effects of the present invention are:

[0025] 1. The leak detection glue of the present invention has the following advantages:

[0026] 1) At room temperature, the viscosity is about 100 - 500 mPa·s, which is moderate. During vacuum guiding, it can guide well and will not flow too fast to be difficult to observe, being suitable for vacuum guiding leak detection. The addition of polyvinyl alcohol enables the glue solution to cure into a film quickly under room temperature and exposed conditions. After forming the film, it can be directly torn off, with high operation efficiency and convenient cleaning; the ethanol aqueous solution promotes the volatilization of the glue solution and speeds up the film-forming rate of the glue solution; glycerol is added by adjusting the proportion, which can further thicken and adjust the viscosity and improve the film-forming quality of the glue solution; tributyl phosphate has the function of accelerating the elimination of bubbles; the addition of the water-based color paste makes the glue solution have an obvious color, and the guiding state of the glue solution is more obvious, which can improve the inspection and determination of leakage points.

[0027] 2) Using water as the main raw material, it is cheap;

[0028] 3) Each component is non-toxic, environmentally friendly, and easy to clean;

[0029] 4) The main components of the torn film material are polyvinyl alcohol, glycerol, and color paste, which can be reused. The collected film can be dissolved in water again and formulated after adding various auxiliary agents, with repeated utilization, cost reduction, environmental friendliness, and non-toxicity.

[0030] 2. The leak point inspection method of the present invention has the following advantages:

[0031] This method uses the above-mentioned leak detection glue solution to guide the flow after sealing on the surface of the mold with a vacuum bag film, etc., allowing it to flow on the surface of the mold at an appropriate flow rate for leak detection. The mold is converted from airtightness inspection to liquid tightness inspection. When there is a leak point, continuous bubbles can be visually seen continuously emerging at the leak point, so as to quickly and accurately determine the leak point; at the same time, through operation methods such as step-by-step feeding and reverse feeding, it can avoid the interference of bubbles formed at the front-end leak point on the subsequent leak point detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The present invention will be further described below in conjunction with the drawings and embodiments. In the drawings:

[0033] Figure 1 is the schematic diagram of the layer between when the leak point inspection method of the mold for vacuum forming of the present invention is used for leak point inspection;

[0034] Figures 2-4 is the process diagram of the leak point inspection of area 1 by the leak point inspection method of the mold for vacuum forming of the present invention;

[0035] Figure 5 is the schematic diagram of the vacuum forming mold used in the embodiment of the present invention.

[0036] In the figure: 1, mold; 2, flow guide net; 3, vacuum bag film; 4, sealing mastic; 5, original feed pipe; 6, original discharge pipe; 7, relay feed pipe; 71, first relay feed pipe; 72, second relay feed pipe; 73, nth relay feed pipe; 8, leak detection glue solution. Detailed implementation manners

[0037] For a clearer understanding of the technical features, objectives, and effects of the present invention, the detailed implementation manners of the present invention will now be described in detail with reference to the accompanying drawings.

[0038] The present invention provides a leak detection glue solution for a mold used in vacuum forming, which includes, by mass: 100 parts of water, 4.5 - 5.5 parts of polyvinyl alcohol, 30 - 40 parts of ethanol aqueous solution, 2 - 8 parts of glycerol, 0.1 - 0.2 parts of tributyl phosphate, and 1 - 2 parts of aqueous pigment paste.

[0039] Further optimization: the molecular weight of the polyvinyl alcohol is 50,000 - 120,000 g / mol.

[0040] Further optimization: the ethanol concentration in the ethanol aqueous solution is 90% - 96%.

[0041] Further optimization: the aqueous pigment paste includes, by mass: 30 - 50 parts of aqueous resin, 15 - 30 parts of organic pigment, 20 - 40 parts of water, 1 - 3 parts of thickener, and 3 - 6 parts of dispersant.

[0042] Further optimization: the aqueous resin uses acrylic emulsion; the organic pigment uses zinc titanate red or phthalocyanine blue or iron oxide yellow; the thickener uses urethane; the dispersant uses sodium lignosulfonate.

[0043] The present invention also provides a method for detecting leak points of a mold used in vacuum forming, and the specific implementation steps are as follows:

[0044] 1) Prepare the above-mentioned leak detection glue solution in advance, and use a vacuum degassing device to degas at -0.1 to -0.098 MPa for 3 - 5 minutes to eliminate its bubbles and then set it aside, so as to avoid small bubbles in the glue solution interfering with subsequent detections.

[0045] 2) As Figure 1As shown in the figure, on the surface of the mold 1, lay 1 layer of flow guiding net 2, cover the vacuum bag film 3 on the surface of the flow guiding net 2, seal the periphery of the vacuum bag film 3 with sealant clay 4, and install the original feed pipe 5 and the original discharge pipe 6 at both ends of the vacuum bag film 3 respectively. Then install several relay feed pipes 7 between the original feed pipe 5 and the original discharge pipe 6. The original feed pipe 5, the original discharge pipe 6 and the relay feed pipes 7 are arranged in parallel with a span of 600 - 1000 mm. Three-way joints are installed in the middle of the original feed pipe 5, the original discharge pipe 6 and the relay feed pipes 7. One end of the three-way joint is used for feeding or connecting the vacuum pump for discharging, and the other two ends are connected to the spiral pipe for guiding flow inside the vacuum bag film.

[0046] 3) Evacuate to a negative pressure at the original discharge pipe 6, clamp the first relay feed pipe 71, the second relay feed pipe 72, and the nth relay feed pipe 73. Inhale the leak detection glue liquid 8 at the original feed pipe 5, and the leak detection glue liquid 8 continuously enters from the end of the original feed pipe 5. As Figure 2 shown, soak the area 1 and check for leakage points in area 1.

[0047] 4) If no continuous leakage bubble source is found in area 1, it proves that the leak detection of area 1 is qualified, and let the leak detection glue liquid continue to soak into area 2 for continued leak detection.

[0048] 5) If a continuous leakage bubble source is found in area 1, with small bubbles continuously bubbling up from the bottom, the source of the bubbling bubbles is the leakage point of the mold. As Figure 3 shown, mark its position. After the leak detection of area 1 is completed, make the following process adjustments to the pipeline: a) Change the end of the original feed pipe 5 to the discharge pipe end, that is, first clamp the end of the original feed pipe 5, clean the glue liquid at the pipe tail, connect the vacuum pump, and convert the negative pressure extraction to the discharge pipe; b) Inject the leak detection glue liquid at the first relay feed pipe 71 and open the vacuum pump valve at the end of the original feed pipe 5 to convert it to discharge. In this way, the leak detection glue liquid enters from the first relay feed pipe 71 and flows towards the end of the original feed pipe 5 and the end of the original discharge pipe 6 respectively. The bubbles formed at the leak point in area 1 will flow back towards the end of the original feed pipe 5 and will not flow into area 2 to interfere with the leak detection. At the same time, re-check the area directly behind the leak point in area 1; at the same time, the leak detection glue liquid continuously soaks towards the end of the original discharge pipe 6 to continue the leak detection of the next area, as Figure 4 shown.

[0049] 6) The leak detection methods for area 2 and subsequent areas are similar to the inspection method for area 1. If the inspection of area 2 is qualified, continue to soak into area 3 for leak detection; if a leak point is found in area 2, after making a mark, clamp the first relay feed pipe 71 and change to feed from the second relay feed pipe 72. The leak detection glue liquid in area 2 flows in the reverse direction towards the end of the original feed pipe 5 to avoid the influence of bubbles on the subsequent areas. At the same time, the leak detection glue liquid in area 3 continuously soaks towards the end of the original discharge pipe 6 to continue the leak detection of the next area.

[0050] 7) And so on until the leak detection work for all areas is completed.

[0051] Table 1 provides four leak detection adhesives, and all the leak detection adhesives are prepared at room temperature.

[0052] Table 1

[0053]

[0054] Example 1:

[0055] A leak detection adhesive for a vacuum forming mold is prepared as follows:

[0056] 1) Weigh the following raw materials by mass: 100 parts of water, 5 parts of polyvinyl alcohol, 35 parts of ethanol aqueous solution, 5 parts of glycerol, 0.15 part of tributyl phosphate, and 1.5 parts of water-based color paste.

[0057] The above water-based color paste is weighed with the following raw materials by mass: 40 parts of water-based resin, 20 parts of organic pigment, 30 parts of water, 2 parts of thickener, and 4.5 parts of dispersant; the water-based resin uses acrylic emulsion, the organic pigment uses zinc titanium red, the thickener uses urethane, and the dispersant uses sodium lignosulfonate.

[0058] 2) When heating 100 parts of water to above 90 °C, add 5 parts of polyvinyl alcohol and stir to dissolve; let it stand and cool naturally to 75 °C, slowly drop 35 parts of ethanol aqueous solution and stir strongly at a speed of 700 r / min; then add 5 parts of glycerol, 1.5 parts of water-based color paste, and 0.15 part of tributyl phosphate in sequence, mix all components evenly, and defoam the adhesive at -0.1 to -0.098 MPa for 5 minutes, and use it after removing its bubbles.

[0059] Sampling and testing are carried out on the leak detection adhesive prepared in this example according to the standard of "GB / T 2794-2022 Determination of Viscosity of Adhesives", and the viscosity measured at room temperature is 225 mPa·s.

[0060] Select a 3000×1000×10 mm vacuum forming mold, and prefabricate 4 0.2 mm defects in the 2800×800 mm area at the center of the mold. The defect positions are shown in Figure 5 , and a leak detection test is carried out under normal temperature conditions. Seal the 2800×800 mm area at the center of the mold with a vacuum bag film, sealing clay, etc., and arrange a relay feed pipe every 700 mm.

[0061] Using the glue solution prepared in Example 1, the 2800×800 mm area at the center of the mold was inspected for leakage points according to the mold leakage point inspection method. The results are as follows: 1) The inspection of all areas was completed in 243 s; 2) The flow rate of the glue solution was moderate; 3) Bubbles could be clearly observed continuously emerging stably at the leakage points, and the leakage point inspection was accurate and clear; 4) All 4 leakage points could be accurately detected, and the leakage point detection rate was 100%; 5) The glue solution formed a film in 106 min after removing the vacuum bag film and the flow guide net; 6) The glue film was easy to clean after forming; 7) The glue film material could be recycled and reused.

[0062] Comparative Example 1:

[0063] A glue solution, the difference in its preparation method from that of Example 1 is that: polyvinyl alcohol and glycerol are not added, and the remaining preparation conditions are the same as those of Example 1.

[0064] Samples of the glue solution prepared in this Comparative Example 1 were tested according to the standard of "GB / T 2794-2022 Determination of Viscosity of Adhesives", and the viscosity measured at room temperature was 3 mPa·s.

[0065] The positions, sizes and quantities of the prefabricated leakage points on the mold were the same as those in Example 1, and the leakage detection temperature, the position of the vacuum bag film and the relay feed pipe were the same as those in Example 1.

[0066] Using the glue solution prepared in this Comparative Example 1, the 2800×800 mm area at the center of the mold was inspected for leakage points according to the mold leakage point inspection method. The inspection results: 1) The inspection of all areas was completed in 35 s; 2) The flow rate of the glue solution was too fast, and the glue solution quickly flowed to the original discharge end, and there was no time to change the original feed pipe to the discharge pipe; 3) The position range of the first leakage point could be roughly seen, but the bubbles formed by the first leakage point affected the observation of the specific positions of the subsequent leakage points; When the positions of the original inlet and outlet pipes were changed and re-inspected, due to a large number of residual bubbles inside, the observation effect was not good; 4) Only the approximate position of the first leakage point could be detected, and there was interference in the determination of the subsequent leakage points, and the leakage point detection rate was 25%; 5) The glue solution did not form a film after removing the vacuum bag film and the flow guide net; 6) The glue solution needed to be thoroughly cleaned, and the cleaning and drying workload was large and time-consuming; 7) The material could not be recycled and reused.

[0067] Comparative Example 2:

[0068] A glue solution, the difference from that of Example 1 is that: tributyl phosphate is not added, and the glue solution is not vacuum degassed, and the remaining preparation conditions are the same as those of Example 1.

[0069] Samples of the leak detection glue solution prepared in this Comparative Example 4 were tested according to the standard of "GB / T 2794-2022 Determination of Viscosity of Adhesives", and the viscosity measured at room temperature was 235 mPa·s.

[0070] The positions, sizes, and quantities of the prefabricated leakage points on the mold are the same as those in Example 1, and the leakage detection temperature, vacuum bag film application, and relay feed pipe position are the same as those in Example 1.

[0071] According to the mold leakage point inspection method, the glue solution prepared in Comparative Example 2 was used to inspect the leakage points in the 2800×800 mm area at the center of the mold. Inspection results: 1) The inspection completion time for all areas was 257 s; 2) The flow rate of the glue solution was moderate; 3) Bubbles were found to continuously emerge stably at the leakage points, but irregular and uninterrupted bubbles were mixed in the glue solution, which had a certain interference with the search and determination of leakage points; 4) All 4 leakage points could be detected, and the leakage point detection rate was 100%; 5) The glue solution formed a film in 108 min after removing the vacuum bag film and the diversion net; 6) The glue solution was easy to clean after forming a film; 7) The film material of the glue could be recycled and reused.

[0072] Comparative Example 3:

[0073] A glue solution, which is different from that in Example 1 in that no ethanol aqueous solution is added, and the remaining preparation conditions are the same as those in Example 1.

[0074] According to the standard of "GB / T 2794-2022 Determination of Viscosity of Adhesives", the leakage detection glue solution prepared in Comparative Example 5 was sampled and tested, and the viscosity measured at room temperature was 310 mPa·s.

[0075] The positions, sizes, and quantities of the prefabricated leakage points on the mold are the same as those in Example 1, and the leakage detection temperature, vacuum bag film application, and relay feed pipe position are the same as those in Example 1.

[0076] According to the mold leakage point inspection method, the glue solution prepared in Comparative Example 3 was used to inspect the leakage points in the 2800×800 mm area at the center of the mold. Inspection results: 1) The inspection completion time for all areas was 326 s; 2) The flow rate of the glue solution was moderate; 3) Bubbles were found to continuously emerge stably at the leakage points; 4) All 4 leakage points could be detected, and the leakage point detection rate was 100%; 5) The glue solution formed a film in 273 min after removing the vacuum bag film and the diversion net, and the film formation was slow; 6) The glue solution was easy to clean after forming a film; 7) The film material of the glue could be recycled and reused.

[0077] The performance test results at room temperature of the leakage detection glue solutions prepared in Example 1 and Comparative Examples 1-3 of the present invention are shown in Table 2.

[0078] Table 2

[0079]

[0080] It can be seen from the comparison in Table 2 that the detection rate of Example 1 is high. For Leak points of 0.2 mm can all be detected. The inspection time for all areas is 243 s, the film-forming time of the glue solution is 106 min, and the glue film is easy to clean and recyclable. In Comparative Example 1, without adding polyvinyl alcohol and glycerol, the viscosity of the glue solution is too small, and the flow rate is too fast to detect leak points. The glue solution does not form a film, is difficult to clean, and is not recyclable. In Comparative Example 2, without adding tributyl phosphate and without vacuum degassing, although all leak points can be detected and the film-forming time of the glue solution is close to that of Example 1, the glue film is well formed, easy to clean, and recyclable, but the air bubbles in the glue solution interfere with the search and determination of leak points. In Comparative Example 3, without adding ethanol aqueous solution, although all leak points can be detected and the glue film is well formed, easy to clean, and recyclable, the film-forming time of the glue solution is too long, reducing the leak point inspection efficiency.

[0081] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other.

[0082] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative rather than restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the purpose of the present invention and the scope protected by the claims. All of these are within the protection scope of the present invention.

Claims

1. A leak detection glue solution for a mold used in vacuum forming, characterized in that The leak detection glue solution includes, by mass: 100 parts of water, 4.5 - 5.5 parts of polyvinyl alcohol, 30 - 40 parts of ethanol aqueous solution, 2 - 8 parts of glycerol, 0.1 - 0.2 parts of tributyl phosphate, and 1 - 2 parts of aqueous color paste.

2. The leak detection glue for the vacuum forming die according to claim 1, characterized in that, The molecular weight of the polyvinyl alcohol is 50000 - 120000 g / mol.

3. The leak detection glue for the vacuum forming mold according to claim 1, characterized in that, The ethanol concentration in the ethanol aqueous solution is 90% - 96%.

4. The leak detection adhesive for the vacuum forming mold according to claim 1, characterized in that, The aqueous color paste includes, by mass: 30 - 50 parts of aqueous resin, 15 - 30 parts of organic pigment, 20 - 40 parts of water, 1 - 3 parts of thickener, and 3 - 6 parts of dispersant.

5. The leak detection glue for the vacuum forming mold according to claim 4, wherein, The aqueous resin uses acrylic emulsion; The organic pigment uses zinc titanium red or phthalocyanine blue or iron oxide yellow; The thickener uses urethane; The dispersant uses sodium lignosulfonate.

6. The leak detection adhesive solution for the vacuum forming die according to claim 1, wherein, The leak detection glue solution is prepared by the following method: When heating 100 parts of water to above 90°C, add 4.5 - 5.5 parts of polyvinyl alcohol, and continuously stir until completely dissolved; Let it stand, naturally cool to 70°C - 78°C, slowly drop 30 - 40 parts of ethanol aqueous solution and continuously stir at a speed of 500 - 1000 r / min; Then add 2 - 8 parts of glycerol, 1 - 2 parts of aqueous color paste, and 0.1 - 0.2 parts of tributyl phosphate in sequence, and stir and disperse evenly.

7. A method for detecting leakage points of a mold for vacuum forming, characterized in that, It includes the following steps: S1. Prepare the leak detection glue solution described in any one of claims 1 - 6 in advance, and conduct defoaming treatment; S2. On the surface of the mold, lay 1 layer of flow guiding net, lay a vacuum bag film on the surface of the flow guiding net, seal the periphery of the vacuum bag film with sealing clay, install a raw material inlet pipe and a raw material outlet pipe at both ends of the vacuum bag film respectively, and then install several relay inlet pipes between the raw material inlet pipe and the raw material outlet pipe; S3. Connect the raw material outlet pipe to a negative pressure device, suck to a negative pressure of -0.1~-0.08 MPa, clamp each relay inlet pipe, suck the leak detection glue solution at the raw material inlet pipe, the leak detection glue solution enters from the end of the raw material inlet pipe, infiltrates and flows to exceed the first relay inlet pipe, check whether there is a leakage point of the mold in the area between the raw material inlet pipe and the first relay inlet pipe. When there is no leakage point, continue to feed from the raw material inlet pipe and check the next interval; When an obvious leakage point of the mold is found, make a record of the leakage point mark, change to enter the leak detection glue solution from the next relay inlet pipe at this leakage point, and change the raw material inlet pipe end to the outlet pipe end. In this way, the leak detection glue solution enters from the first relay inlet pipe and flows respectively towards the raw material inlet pipe end and the raw material outlet pipe end. On the one hand, the bubbles formed between the raw material inlet pipe end and the first relay inlet pipe will be pumped to the raw material inlet pipe end to avoid interfering with the leak detection of the next interval. On the other hand, the leak detection glue solution continuously infiltrates towards the raw material outlet pipe end to continue to check the mold tightness of the next interval; S4. And so on until the leak detection of all intervals is completed.

8. The method for detecting leakage points of the mold for vacuum forming according to claim 7, characterized in that, In step S1, the defoaming treatment method is: using a vacuum defoaming device, defoam the leak detection glue solution at -0.098~-0.1 MPa for 3 - 5 minutes, eliminate its bubbles and then use it, to avoid the small bubbles in the leak detection glue solution interfering with the subsequent detection.

9. The method for detecting leakage points of the mold for vacuum forming according to claim 7, wherein, The original feed pipe, the original discharge pipe and the relay feed pipe are arranged in parallel with a span of 600 - 1000 mm; three-way joints are installed in the middle of the original feed pipe, the original discharge pipe and the relay feed pipe.

10. The method for detecting leakage points of the mold for vacuum forming according to claim 7, characterized in that, In step S3, the basis for judging the leakage point of the mold is: when bubbles continuously bubble up from the bottom, the source of the bubbling bubbles is the leakage point of the mold; the method for marking the leakage point is: use a marker pen to draw a circle at the corresponding position on the surface of the vacuum bag film.

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