CN112696540A

CN112696540A - Permeation-resistant three-layer heat exchange tube and preparation method thereof

Info

Publication number: CN112696540A
Application number: CN202011560055.XA
Authority: CN
Inventors: 张志超; 邓小东; 王冰
Original assignee: Zhongshan Schlemmer Automotive Parts Co ltd
Current assignee: Zhongshan Schlemmer Automotive Parts Co ltd
Priority date: 2020-12-25
Filing date: 2020-12-25
Publication date: 2021-04-23

Abstract

The invention relates to a permeation-resistant three-layer heat exchange tube, which comprises an inner layer made of a PP material; an adhesive layer made of an adhesive material containing PP; and an outer layer made of a PA material. The invention also relates to a preparation method of the penetration-resistant three-layer heat exchange tube. The heat exchange tube not only has excellent hydrolysis resistance and ageing resistance on the inner layer, but also can adapt to the change of the external environment on the outer layer, thereby ensuring that the cooling effect meets the requirement, ensuring that the service life of an automobile battery system is longer and the stability of automobile parts is better.

Description

Permeation-resistant three-layer heat exchange tube and preparation method thereof

Technical Field

The invention relates to the technical field of heat exchange tubes, in particular to a permeation-resistant three-layer heat exchange tube and a preparation method thereof.

Background

With the development of economy and the continuous improvement of the living standard of human beings, countries around the world increasingly pay attention to ecological development, the requirements on automobile emission are more and more strict in automobile use, and various automobile factories are dedicated to developing new energy vehicles taking batteries as power.

A new energy electric vehicle BMS (battery management system) needs to install a heat exchange pipe (cooling pipe). The battery system of the new energy vehicle is characterized in that circulating cooling liquid is introduced into the heat exchange pipe to cool the battery pack, and the cooling liquid mainly comprises water, an anti-freezing agent, an additive and the like. The medium flowing through the cooling pipeline of the battery system of the new energy vehicle is cooling liquid with water as a main component. When the electric vehicle runs, the internal temperature of the battery can reach about 60 ℃, and the heat exchange tube is required to have the characteristic of high temperature resistance, so most heat exchange tubes in the market are single-layer tubes made of PA materials with heat resistance.

The medium that flows through in the cooling pipeline of new energy car battery system is the coolant liquid that the main component was water, but because ordinary single-deck cooling tube is made for the PA material, and the PA material is hydrophilic plastics, and it is relatively poor to separate hydrolysis resistance, therefore, the coolant liquid in the heat exchange tube permeates the external evaporation through the pipeline material easily. After a long time of use, the cooling liquid in the heat exchange tube can be gradually reduced. In addition, because the hydrolysis resistance of the common single-layer cooling pipe is poor, after long-time use, the inner side of the pipe is easy to age and even generate cracks, so that cooling liquid in the cooling pipe is easy to leak, the cooling effect is further seriously influenced, the loss of the automobile is increased, and the single-layer cooling pipe is undoubtedly a substantial defect for the automobile.

Therefore, how to develop a heat exchange tube with hydrolysis resistance and coolant permeation resistance to meet the requirement of a cooling pipeline of a battery system in a new energy automobile becomes a technical problem to be solved urgently in the field.

Disclosure of Invention

The invention aims to overcome the defects of the prior art, provides a three-layer heat exchange tube with better permeation resistance, and also provides a preparation method of the three-layer heat exchange tube.

The technical scheme adopted by the invention is as follows: a permeation resistant three layer heat exchange tube comprising:

an inner layer made of a PP (polypropylene) material;

an adhesive layer made of an adhesive material containing PP; and

and the outer layer is made of PA12 (polyamide 12) material.

Preferably, the PA material is PA12 (polyamide 12).

Preferably, the PP-containing adhesive material of the adhesive layer is made of an adhesive material containing an anhydride grafted polypropylene.

A preparation method of a permeation-resistant three-layer heat exchange tube comprises the following steps:

firstly, putting materials of an inner layer, an adhesive layer and an outer layer into a multi-handpiece co-extrusion extruder to extrude a three-layer tubular mechanism; the permeability resistance of the heat exchange tube is met by adjusting different proportions of PA12 and PP and adjusting the thickness of the product.

Step two, cooling and forming;

step three, cutting the pipe;

step four, heat setting: and (5) shaping the pipe as required.

Preferably, in the first step, the extrusion temperature of the inner layer is 230-.

Preferably, the extrusion temperature of the adhesive layer in the first step is 225-255 ℃, and the extrusion material hydraulic pressure is set to be 90-130 bar.

Preferably, in the first step, the extrusion temperature of the outer layer is 225-255 ℃, and the extrusion material hydraulic pressure is set to be 145-180 bar.

Compared with the prior art, the invention has the following advantages:

1. the PP inner layer of the heat exchange tube has hydrolysis resistance, and can effectively prevent the cooling liquid in the tube from seeping out, so that the heat exchange tube has the characteristic of permeation resistance, and the service life of the cooling liquid is prolonged. The heat exchange tube of the invention has no obvious change in weight loss under the temperature environment of 60 ℃, which shows that the heat exchange tube of the invention can still keep better cooling performance under the state of continuous starting of the automobile and prevent the cooling liquid from permeating into the outside through the pipeline material to be evaporated.

2. The outer layer of the heat exchange tube is made of PA12 material, has particularly high long-term tolerance under heat load, and can adapt to the change of external environment; and the material only absorbs little moisture, so that the cooling pipeline is hardly influenced under the constantly changing environmental conditions, the use problem of the single-layer cooling pipeline in the prior art is solved, the cooling effect is ensured to meet the requirement, the service life of the automobile battery system is longer, and the stability of automobile parts is better.

3. The material of the bonding layer of the heat exchange tube is a PP material, so that the heat exchange tube has excellent adhesive force with the inner layer and the outer layer, and simultaneously keeps better thermal stability, so that the inner layer and the outer layer are not easy to peel.

4. The heat exchange tube has relatively light weight, does not occupy the internal space, and does not increase the loss of an automobile; can adapt to the arrangement form of the battery pack pipeline, has good flexibility, and is convenient to assemble and package.

Description of the drawings:

FIG. 1 is a schematic view of the structure of a light pipe according to embodiment 1

Fig. 2 is a schematic structural view of the bellows.

Fig. 3 is a schematic cross-sectional view of fig. 2.

The specific implementation mode is as follows:

in order to enhance the understanding of the present invention, the present invention will be described in further detail with reference to embodiments. The invention can be implemented by:

the penetration-resistant three-layer heat exchange tube comprises three layers of materials from inside to outside, wherein the three layers of materials are respectively as follows: an inner layer made of a PP material, an adhesive layer made of an adhesive material containing PP, and an outer layer made of a PA12 material. The adhesive layer serves to bond the inner and outer layers.

The inner layer is made of PP material and is thermoplastic resin. Has better hydrolysis resistance, chemical resistance and mechanical property. Can resist the corrosion of acid, alkali, salt solution and various organic solvents at the temperature of below 80 ℃. Can effectively prevent the cooling liquid in the tube from seeping out, so that the heat exchange tube has the characteristic of permeation resistance,

the material of the bonding layer is a PP material, the PP material is made of bonding material containing anhydride grafted polypropylene, namely modified polyolefin consisting of modified polyethylene and modified polypropylene, and because the bonding functional group is introduced on the polyolefin chain, the bonding layer can have better adhesive force with the outer layer and the inner layer, and has extremely strong bonding property during bonding; and has excellent processing performance. In addition, the PP bonding layer keeps the mechanical and heat-resistant characteristics of polyolefin, has better thermal stability and can adapt to the environment with constantly changing temperature. In addition, the PP material used as the adhesive layer has compatibility with the PP inner layer on one hand, and the adhesive functional group can chemically react with the PA outer layer in the adhesion process on the other hand, so that the adhesiveness of the adhesive layer and the inner and outer layers is further increased.

The PA material is PA12 (polyamide 12), the outer layer is PA12 material, the heat distortion temperature (0.45MPa, non-annealed) of the PA12 of the outer layer reaches 130 ℃, and the Vicat softening temperature (ISO306/A) reaches 165 ℃. The PA12 material has high long-term tolerance under heat load, and can be suitable for environmental conditions with constantly changing temperature. The heat exchange tube provided by the invention utilizes the PA12 material as an outer protective layer and the PP material as an inner anti-permeation layer, so that the service life of an automobile battery system is longer and the stability of automobile parts is better while the cooling effect meets the requirement.

Example 1

The permeation resistant heat exchange tube of the present invention can be made into a light pipe comprising an inner layer of PP, an adhesive layer and an outer layer of PA 12. The preparation method comprises the following steps:

firstly, putting materials of an inner layer, an adhesive layer and an outer layer into a multi-compound extruder to extrude a three-layer tubular mechanism; setting the extrusion temperature of the inner layer to be 240 ℃ and the hydraulic pressure of the extrusion material to be 170 bar; the extrusion temperature of the adhesive layer was 240 ℃ and the extrusion material liquid pressure was 120 bar; the extrusion temperature of the outer layer was 240 ℃ and the extrusion feed liquid pressure was 170 bar. The thickness of the inner layer is controlled to be min (minimum) 0.5mm during extrusion, the thickness of the bonding layer is controlled to be min0.1, the thickness of the outer layer is controlled to be min0.75mm, and the thickness of the tube wall is controlled to be 1.5 +/-0.15 mm.

Step two, cooling and forming;

step three, cutting the pipe;

step four, heat setting to form the light pipe, and the shape can refer to the figure 1.

Example 2

firstly, putting materials of an inner layer, an adhesive layer and an outer layer into a multi-compound extruder to extrude a three-layer tubular mechanism; setting the extrusion temperature of the inner layer to be 245 ℃ and the extrusion material liquid pressure to be 160 bar; the extrusion temperature of the adhesive layer was 245 ℃, and the extrusion material liquid pressure was 100 bar; the extrusion temperature of the outer layer was 245 ℃ and the extrusion hydraulic pressure was 155 bar. The thickness of the inner layer, adhesive layer, outer layer and the entire tube wall was controlled during extrusion as in example 1.

The second, third and fourth steps are the same as in example 1.

Example 3

The permeation resistant heat exchange tube of the present invention can be made into a corrugated tube, which also comprises a PP inner layer, an adhesive layer and a PA12 outer layer. The construction of the bellows is shown in fig. 2-3.

The samples prepared according to the invention were subjected to the following performance tests:

1. elongation at break:

the test method comprises the following steps: the sample of the invention is mounted on a test platform, the sample tube is stretched until breaking, the displacement is recorded, and the elongation at break is calculated.

Detection standard: elongation at break test: the pulling speed is 200 mm/min; the elongation at break is more than or equal to 150 percent.

And (3) testing results:

2. and (3) negative pressure testing:

and (3) testing conditions are as follows: air was used as the test medium, the test pressure was 30mBar, the ambient pressure was 1013mBar, the test temperature was 22(+5/-2), the dwell time was 60S, and the cycle number was 5 times.

Detection standard: the maximum leakage value after stabilization was 0.5 cc/min.

And (3) testing results: the tested leakage value is between 0.19 and 0.30, and the requirements are met.

3. Testing the side strength:

and (3) testing conditions are as follows:

side load leakage test: the sample was mounted onto the male connector on the fixture and the other end sealed. Compressed air of 4bar was applied internally. A force of 152N was applied laterally and the hermeticity was examined.

Side fracture test: referring to SAE J2044, the quick connector and tubing assembly is mounted to the male connector on the fixture and a lateral force is applied at a rate of 12.7 + -5 mm/min until a specified force is reached or the quick connector breaks.

And (4) testing standard:

side load leakage test: the lateral force F was 152N and the maximum leakage was 0.5 cc/min.

Side fracture test: the lateral force is more than 200N.

And (3) testing results: the samples are not damaged and meet the requirements.

4. And (3) room temperature blasting test:

and (3) testing conditions are as follows: introducing compressed air/water pressure under room temperature environment, pressurizing to 3.5Bar, maintaining pressure for 60S (no leakage should exist), pressurizing at interval of 0.5Bar until failure, maintaining pressure for 60S each time, and recording failure pressure and position.

And (4) testing standard: the failure pressure is greater than 800 KPa.

And (3) testing results: the failure pressure is 2.0-2.1MPa, which meets the requirement.

5. High-temperature blasting test:

and (3) testing conditions are as follows: introducing compressed air/water pressure at 85 deg.C, pressurizing to 3.5Bar, maintaining pressure for 60S (no leakage), pressurizing at 0.5Bar interval to failure, maintaining pressure for 60S, and recording failure pressure and position.

And (4) testing standard: the failure pressure is greater than 800 KPa.

And (3) testing results: the failure pressure is 0.85-0.9MPa, which meets the requirements.

6. Cleanliness:

and (3) testing conditions are as follows: injecting an antifreeze solution accounting for about 60% of the volume of the inner cavity of the tested product, placing the test product on a vibration test bed with the oscillation frequency of 275 times/min for oscillation for 2 hours, pouring out the solvent, flushing the inner cavity with clean nitrogen, filtering with 1.6 mu filter paper, evaporating the filter paper in an oven at 60 ℃ for 1 hour before and after filtration, returning to the room temperature, and respectively measuring the mass difference before and after the filter paper test.

And (4) testing standard: the residual impurity amount in the tube is less than or equal to 30mg, and the grain diameter of the largest solid particle is less than 1 mm.

And (3) testing results: the residual impurity amount in the tube is less than or equal to 26mg, and the grain diameter of the largest solid particle is less than 1mm, which meets the requirements.

7. And (3) high temperature resistance test:

and (3) testing conditions are as follows: 70 percent of ethylene glycol and 30 percent of water (volume ratio) are introduced into the reactor, the surface pressure is 130Kpa, the test time is 450h, the environment temperature is 110 +/-5 ℃, the medium temperature is 110 +/-5 ℃, and the sealing test is carried out at 200 h.

And (4) testing standard: visual inspection did not affect use.

And (3) testing results: visual inspection of the appearance of the sample has no damage, does not influence the use, and meets the requirements.

8. Pressure alternation + temperature alternation

And (3) testing conditions are as follows: testing 70% glycol and 30% water in medium, wherein the pressure curve is sine distribution, the frequency is about 1Hz, the lowest gauge pressure is 0.5 +/-0.2 bar, the best gauge pressure is 3.5 +/-0.2 bar, the testing process a and 10000 pressure circulation, the medium temperature is-20 +/-3 ℃, and the environment temperature is-40 +/-3 ℃; b. 90000 pressure cycle, medium temperature is-80 + -3 deg.C, and ambient temperature is 80 + -3 deg.C; c. 10000 pressure circulation, medium temperature is-20 + -3 deg.C, environment temperature is-40 + -3 deg.C; d. 90000 pressure cycle, medium temperature-80 + -3 deg.C, and ambient temperature-80 + -3 deg.C.

And (4) testing standard: visual inspection did not affect use.

9. The life cycle is as follows:

and (3) testing conditions are as follows: the joint plus tubing assembly was mounted on a fixture and vibration from 7Hz to 200Hz was applied continuously with frequency adjustment three times per hour. While applying a pressure varying from 0 to 4bar, adjusted once per minute. The experiment lasted 336h and only the hot-running test was performed (see SAEJ2044-2009 for requirements). Wherein, the testing medium adopts G48/water, the fluid flow passing through each quick-connection plug is 1.33Lpm and 0.2Lpm, the maximum testing pressure is adjusted to be 4bar, the maximum environment temperature is adjusted to be +100 ℃, and the maximum medium temperature is +85 ℃.

And (4) testing standard: visual inspection did not affect use.

From the elongation at break, the negative pressure test, the side strength test, the room temperature blasting test, the high temperature blasting test, the cleanliness, the high temperature resistance test, the pressure alternation plus the temperature alternation and the life cycle test of the above 1 to 9, the heat exchange tube can meet the performance required by the common heat exchange tube in a new energy automobile.

10. And (3) penetration resistance test:

moisture vapor permeation rate: the sample was filled with a cooling liquid (ethylene glycol: pure water ═ 1:1(v/v)), and placed in an environment at 60 ℃ for a test of 672h, during which the cooling liquid was changed 4 times. The replacement time is 168h, 336h, 504h and 672 h. The mass loss was measured starting after 672h and weighing every 24h starting at 1008 h; and continuing to perform the test at 60 ℃ for 1200h, and calculating the total mass loss and the total permeability according to the following formulas.

Total mass loss, g 672h mass-1200 h mass

Total permeability, g/h total mass loss/test time (528h)

The test results are shown in the following table:

from the above permeability test, it can be seen that the cooling liquid of the heat exchange tube continues without significant change in weight loss under the temperature environment lasting 60 ℃. The heat exchange tube of the invention can still keep better cooling performance under the state that the automobile is continuously started.

Finally, it should be noted that: the above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that are within the spirit and principle of the present invention are intended to be included in the scope of the present invention.

Claims

1. A permeation resistant three layer heat exchange tube comprising:

an inner layer made of a PP material;

an adhesive layer made of an adhesive material containing PP; and

and the outer layer is made of PA material.

2. A permeation resistant three layer heat exchange tube as claimed in claim 1, wherein said PA material is PA 12.

3. The permeation resistant three-layer heat exchange tube as claimed in claim 2, wherein the PP-containing adhesive material of the adhesive layer is made of an adhesive material containing an acid anhydride grafted polypropylene.

4. A preparation method of a permeation-resistant three-layer heat exchange tube is characterized by comprising the following steps:

firstly, putting materials of an inner layer, an adhesive layer and an outer layer into a multi-handpiece co-extrusion extruder to extrude a three-layer tubular mechanism;

step two, cooling and forming;

step three, cutting the pipe;

and step four, heat setting.

5. The method as claimed in claim 4, wherein the extrusion temperature of the inner layer in the step one is 230-255 ℃, and the pressure of the extrusion material is 150-180 bar.

6. The method as claimed in claim 4, wherein the extrusion temperature of the adhesive layer in the first step is 225 ℃ and 255 ℃, and the extrusion hydraulic pressure is 90-130 bar.

7. The method as claimed in claim 4, wherein the extrusion temperature of the outer layer in the first step is 225-255 ℃, and the pressure of the extrusion material is 145-180 bar.