A low-temperature and atmospheric-pressure plasma surface hydrophilic modification device and method based on a carbon dioxide atmosphere

Abstract

The present invention discloses a device and method for low-temperature and atmospheric-pressure plasma surface hydrophilic modification based on a carbon dioxide atmosphere. The device includes a carbon dioxide gas supply unit, a plasma treatment chamber, and a conveyor belt. The plasma treatment chamber includes a generation chamber and a post-reaction chamber. A positive electrode and a negative electrode are provided in the generation chamber. The positive electrode is electrically connected to an external control power supply, and the negative electrode is grounded. The carbon dioxide gas supply unit is located at the top of the plasma treatment chamber. The bottom of the carbon dioxide gas supply unit is connected to a gas pipe, and the gas pipe extends to the bottom of the generation chamber. A control switch is provided at the connection between the carbon dioxide gas supply unit and the gas pipe, and the control switch is electrically connected to a pressure sensor, which is located at the top of the generation chamber. The conveyor belt is of a U-shaped structure and passes through the generation chamber and the post-reaction chamber in sequence. The positive electrode is located above the conveyor belt, and the negative electrode is located below the conveyor belt. The device and method of the invention can continuously prepare modified films.

Description

Technical Field

[0001] The present invention relates to the technical field of green manufacturing, and particularly relates to a low-temperature and atmospheric-pressure plasma surface hydrophilic modification device and method based on a carbon dioxide atmosphere. Background Art

[0002] Global warming caused by the emission of greenhouse gases mainly composed of carbon dioxide is seriously threatening the survival and sustainable development of mankind, and is one of the major global challenges currently faced by mankind. In order to promote green, circular and low-carbon development, China has proposed to strive to achieve carbon peak before 2030 and carbon neutrality before 2060. At the same time, the task of improving environmental quality in China at the present stage is still severe, and the goal of carbon neutrality provides a basic guideline for us to promote environmental pollution prevention and control and greenhouse gas emission reduction. To achieve the goal of carbon neutrality, in addition to reducing fossil energy consumption and vigorously developing new energy, it is also possible to start from the collection and utilization of the already emitted carbon dioxide. At present, many studies have focused on the adsorption and energy-based recycling of carbon dioxide. Among them, the research on catalytic decomposition of carbon dioxide by plasma technology has become one of the hotspots in the research on carbon dioxide energy utilization. However, the current conversion rates of carbon monoxide or methane obtained are not ideal, and the utilization rate of carbon dioxide is not high.

[0003] Plasma surface treatment technology is to excite gas molecules with a certain amount of energy, dissociate the gas into electrons, ions, free radicals and other excited states such as metastable states, collide with the material surface, break covalent bonds, generate free radicals, and activate the material surface. And the activated material surface can combine with the excited gas to generate chemically active groups on the surface. Low-temperature and atmospheric-pressure atmospheric plasma treatment technology has been widely used in industries such as electroplating, coating, and ink printing to improve interface bonding.

[0004] In summary, with carbon dioxide as the atmosphere, plasma technology can be used to effectively activate and utilize carbon dioxide, generate more hydrophilic groups on the polymer film, thereby realizing the reuse of carbon dioxide while hydrophilically modifying the surface of the polymer film and reducing the emission of carbon dioxide into the environment. Summary of the Invention

[0005] The purpose of the present invention is to propose a low-temperature and atmospheric-pressure plasma surface hydrophilic modification device with a carbon dioxide atmosphere, which can ionize carbon dioxide with high energy under atmospheric pressure, not only realize continuous hydrophilic modification of the surface of hydrophobic polymer films, but also realize the reuse of carbon dioxide and reduce carbon dioxide emissions.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] On the one hand, the present invention provides a low-temperature and atmospheric-pressure plasma surface hydrophilic modification device based on a carbon dioxide atmosphere. The device includes a carbon dioxide gas supply unit, a plasma treatment chamber, and a conveyor belt.

[0008] The plasma treatment chamber includes a generation chamber and a post-reaction chamber. A positive electrode and a negative electrode are provided in the generation chamber. The positive electrode is electrically connected to an external control power supply, and the negative electrode is grounded.

[0009] The carbon dioxide gas supply unit is located at the top of the plasma treatment chamber. The bottom of the carbon dioxide gas supply unit is connected to a gas pipe, and the gas pipe extends to the bottom of the generation chamber. A control switch is provided at the connection between the carbon dioxide gas supply unit and the gas pipe, and the control switch is electrically connected to a pressure sensor, which is located at the top of the generation chamber.

[0010] The conveyor belt is of a U-shaped structure. The conveyor belt sequentially passes through the generation chamber and the post-reaction chamber. The positive electrode is located above the conveyor belt, and the negative electrode is located below the conveyor belt. The conveyor belt is embedded between the positive electrode and the negative electrode. The negative electrode consists of at least two conveyor rollers, and the rotation of the conveyor rollers drives the movement of the conveyor belt. The film to be treated is attached to the surface of the conveyor belt.

[0011] Furthermore, blowers are installed at the lower left corner of the generation chamber and the upper right corner of the post-reaction chamber.

[0012] Furthermore, the distance between the positive electrode and the negative electrode is 10 mm - 500 mm.

[0013] Furthermore, the positive electrode is a rod-shaped or tubular electrode made of a highly conductive metal.

[0014] Furthermore, the highly conductive metal is one of iron, copper, and silver.

[0015] Furthermore, the negative electrode is made of stainless steel, and an insulating coating is attached to the surface of the negative electrode.

[0016] Furthermore, the material of the insulating coating is Al2O3 or Ca 0.8 Sr 0.2 TiO3.

[0017] Furthermore, an inlet is provided at the upper left corner of the generation chamber, and an outlet is provided at the upper right corner of the post-reaction chamber. The conveyor belt enters the generation chamber from the inlet and leaves the post-reaction chamber from the outlet. Sealing structures are provided at both the inlet and the outlet, and the sealing structures are two elastically silicone rubber sheets arranged in the same direction.

[0018] On the other hand, the present invention also provides a low-temperature and atmospheric-pressure plasma surface hydrophilic modification method based on a carbon dioxide atmosphere. The method includes the following steps:

[0019] S1: Attach the film to be treated to the conveyor belt;

[0020] S2: Turn on the control switch, and the carbon dioxide in the carbon dioxide supply unit enters the reaction chamber until the air pressure sensor detects that the air pressure in the reaction chamber is equal to one atmosphere.

[0021] S3: Turn on the control power switch, the plasma generating electrode starts to discharge, rotate the conveyor roller, the conveyor roller drives the conveyor belt to move, and the film to be processed attached to the surface of the conveyor belt passes through the reaction chamber and the post-reaction chamber in sequence.

[0022] Furthermore, the operating power of the control power supply is 50W - 50kW; the positive electrode discharge frequency is 10kHz - 100MHz;

[0023] The running time of the film to be processed in the reaction chamber is 3 - 5 minutes, and the running time in the post-reaction chamber is 1 - 3 minutes.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] (1) The low-temperature atmospheric pressure plasma surface hydrophilic modification device based on carbon dioxide atmosphere of the present invention realizes the secondary utilization of carbon dioxide. The positive electrode, negative electrode and conveyor belt are placed at the bottom of the reaction chamber, and both the inlet and outlet of the conveyor belt are located at the top of the processing chamber. Since carbon dioxide has a high specific gravity, it can discharge air from the top of the chamber, thus filling the reaction chamber with carbon dioxide gas and ensuring that the plasma generation atmosphere is carbon dioxide.

[0026] (2) The low-temperature atmospheric pressure plasma surface hydrophilic modification device based on carbon dioxide atmosphere of the present invention, compared with the vacuum plasma treatment device, does not require vacuum treatment and can be carried out under normal pressure. The elastic silica gel sheets arranged unidirectionally at the inlet and outlet positions can not only ensure the airtightness of the processing chamber but also ensure the continuity of the conveyor belt input and output, and can realize continuous film hydrophilic treatment.

[0027] (3) The low-temperature atmospheric pressure plasma surface hydrophilic modification device based on carbon dioxide atmosphere of the present invention, the gas ions excited by the plasma to ionize carbon dioxide bombard the surface of the film to be processed, making the film surface activated. By controlling the conveyor belt speed, after the film to be processed is subjected to plasma treatment in the reaction chamber for 3 - 5 minutes and then runs in the post-reaction chamber for 1 minute, it ensures that the activated groups on the film surface and the ionized gas ions undergo sufficient bonding reactions. Based on experiments, the surface activated by the plasma becomes inactivated within 1 - 2 minutes in the air.

[0028] (4) Taking pp spunbond non-woven fabric as an example, for the low-temperature atmospheric pressure plasma surface hydrophilic modification device based on carbon dioxide atmosphere of the present invention, the contact angle of the film surface with water can be reduced from 95 o to 32 o, the hydrophilic modification of the thin film was successfully achieved. Analysis of the surface functional groups of the thin film with an infrared spectrometer found that absorption peaks of hydrophilic groups -OH and C-O appeared on the surface of the modified PP spunbond nonwoven fabric. Description of the Drawings

[0029] Figure 1 It is a schematic structural diagram of a low-temperature and atmospheric-pressure plasma surface hydrophilic modification device based on a carbon dioxide atmosphere.

[0030] 1 - Carbon dioxide supply unit; 11 - Gas pipe; 12 - Control switch; 13 - Pressure sensor; 2 - Plasma treatment chamber; 21 - Generation chamber; 22 - Post-reaction chamber; 23 - Positive electrode; 24 - Negative electrode; 25 - Blower; 26 - Inlet; 27 - Outlet; 3 - Conveyor belt. Specific Embodiments

[0031] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0032] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", "front", "rear", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation of the present invention. In the present invention, it should also be noted that the terms "installation" and "connection" should be understood in a broad sense. For example, it can be fixedly connected, or it can be detachably connected, or it can be mechanically connected, or it can be indirectly connected through an intermediate medium, or it can be electrically connected. The specific meaning of the terms in the present invention can be understood according to specific situations.

[0033] Example 1

[0034] The present invention provides a low-temperature and atmospheric-pressure plasma surface hydrophilic modification device based on a carbon dioxide atmosphere, as Figure 1 shown. The device includes a carbon dioxide supply unit 1, a plasma treatment chamber 2 and a conveyor belt 3.

[0035] The plasma treatment chamber 2 includes a generation chamber 21 and a post-reaction chamber 22. A positive electrode 23 and a negative electrode 24 are provided in the generation chamber 21. The positive electrode 23 is electrically connected to an external control power supply, and the negative electrode 24 is grounded.

[0036] The carbon dioxide supply unit 1 is located at the top of the plasma processing chamber 2. The bottom of the carbon dioxide supply unit 1 is connected to the air pipe 11, and the air pipe 11 extends to the bottom inside the reaction chamber 21. A control switch 12 is provided at the connection between the carbon dioxide supply unit 1 and the air pipe 11. The control switch is electrically connected to the pressure sensor 13, and the pressure sensor 13 is located at the top inside the reaction chamber 21.

[0037] The conveyor belt 3 is of U-shaped structure. The conveyor belt 3 passes through the reaction chamber 21 and the post-reaction chamber 22 in sequence. The positive electrode 23 is located above the conveyor belt 3, and the negative electrode 24 is located below the conveyor belt 3. The conveyor belt 3 is embedded between the positive electrode 23 and the negative electrode 24. The negative electrode 24 consists of at least two conveyor rollers. The rotation of the conveyor rollers drives the conveyor belt 3 to move, and the film to be processed adheres to the surface of the conveyor belt 3.

[0038] Specifically, the carbon dioxide supply unit 1 can continuously supply gas to the plasma reaction chamber 21 to ensure that the air pressure in the reaction chamber 21 is the same as the external air pressure.

[0039] The pressure sensor 13 senses the gas pressure inside the plasma processing chamber 2. Once the pressure inside the chamber is lower than one atmosphere, gas will be discharged through the air pipe 11 into the bottom of the plasma processing chamber 2 to ensure that carbon dioxide is filled from the bottom of the reaction chamber 21.

[0040] The control switch 12 includes a manual switch and an automatic switch. The manual switch is used to discharge the air inside the plasma processing chamber before plasma discharge; the automatic switch is used for the automatic filling of carbon dioxide during the plasma processing.

[0041] Specifically, a blower 25 is installed at the lower left corner of the reaction chamber 21 and the upper right corner of the post-reaction chamber 22. The blower 25 ensures that the ionized carbon dioxide gas fills the entire plasma processing chamber.

[0042] Specifically, the distance between the positive electrode 23 and the negative electrode 24 is 10 mm - 500 mm.

[0043] Specifically, the positive electrode 23 is a rod-shaped or tubular electrode made of a highly conductive metal.

[0044] Specifically, the highly conductive metal is one of iron, copper, and silver.

[0045] Specifically, the negative electrode 24 is made of stainless steel, and an insulating coating is attached to the surface of the negative electrode 24.

[0046] Specifically, the material of the insulating coating is Al2O3 or Ca 0.8 Sr 0.2 TiO3.

[0047] Specifically, an inlet 26 is provided at the upper left corner of the reaction chamber 21, and an outlet 27 is provided at the upper right corner of the post-reaction chamber 22. The conveyor belt 3 enters the reaction chamber 21 from the inlet 26 and leaves the post-reaction chamber 22 from the outlet 27. Sealing structures are provided at both the inlet 26 and the outlet 27, and the sealing structures are two elastically silicone rubber sheets arranged in the same direction. The elastically silicone rubber sheets are arranged unidirectionally, which not only functions as a sealing device but also ensures the unidirectional operation of the conveyor belt 3.

[0048] This device can be used not only for carbon dioxide recycling but also for surface hydrophilic modification of coatings, films, non-woven fabrics, and fabrics such as polypropylene and polyester.

[0049] After being treated with the device of the present invention, the contact angle of the surface of the polypropylene non-woven fabric film with water can be reduced from 95 o to 60 o , successfully realizing the hydrophilic modification of the polypropylene non-woven fabric film. Absorption peaks of hydrophilic groups -OH and C-O appear on the surface of the modified polypropylene non-woven fabric.

[0050] Example 2

[0051] The present invention provides a low-temperature and atmospheric-pressure plasma surface hydrophilic modification method based on a carbon dioxide atmosphere. Using the above device, the method includes the following steps:

[0052] S1: Attach the film to be treated to the conveyor belt 3;

[0053] S2: Turn on the control switch, and carbon dioxide in the carbon dioxide supply unit 1 enters the reaction chamber 21 until the pressure sensor 13 detects that the air pressure in the reaction chamber 21 is equal to one atmosphere;

[0054] S3: Turn on the control power switch, the plasma generating electrode starts to discharge, rotate the conveyor roller, and the conveyor roller drives the conveyor belt 3 to move. The film to be treated attached to the surface of the conveyor belt 3 sequentially passes through the reaction chamber 21 and the post-reaction chamber 22.

[0055] Specifically, the operating power of the control power supply is 50W - 50kW; the discharge frequency of the positive electrode 23 is 10kHz - 100MHz.

[0056] The running time of the film to be treated in the reaction chamber 21 is 3 - 5 minutes, and the running time in the post-reaction chamber 22 is 1 - 3 minutes.

[0057] Specifically, manually turn on the switch of the carbon dioxide supply unit 1, fill carbon dioxide gas into the bottom of the plasma treatment chamber, and use the principle that carbon dioxide is heavier than air to discharge air from the top outlet position. After inflating for 15 minutes, turn the switch of the carbon dioxide gas storage tank to the automatic state; turn on the blowers on both sides of the treatment chamber, and the gas flows in a circular pattern in the treatment chamber.

[0058] Compared with the prior art, the present invention has the following beneficial effects:

[0059] (1) The low-temperature, atmospheric-pressure plasma surface hydrophilic modification device based on carbon dioxide atmosphere of the present invention realizes the secondary utilization of carbon dioxide. The positive electrode, negative electrode and conveyor belt are placed at the bottom of the reaction chamber, and the conveyor belt inlet and outlet are both located at the top of the treatment chamber. Carbon dioxide has a high specific gravity, and air can be discharged from the top of the chamber, thereby filling the reaction chamber with carbon dioxide gas, ensuring that the plasma generation atmosphere is carbon dioxide;

[0060] (2) The low-temperature, normal-pressure plasma surface hydrophilic modification device based on carbon dioxide atmosphere of the present invention does not require vacuum treatment compared to vacuum plasma treatment devices, and can be carried out under normal pressure. The elastic silicone sheets arranged unidirectionally at the inlet and outlet positions can ensure the airtightness of the treatment chamber and the continuity of the conveyor belt input and output, thereby achieving continuous thin film hydrophilic treatment;

[0061] (3) The present invention uses a low-temperature, atmospheric-pressure plasma surface hydrophilic modification device based on a carbon dioxide atmosphere. The plasma excites the carbon dioxide ionized gas ions to bombard the surface of the film to be treated, thereby activating the film surface. By controlling the conveyor belt speed, the film to be treated is subjected to plasma treatment in the reaction chamber for 3-5 minutes and then runs in the post-reaction chamber for 1 minute to ensure that the activated groups on the film surface undergo sufficient bonding reaction with the ionized gas ions. Based on experimental evidence, the surface activated by plasma is deactivated after 1-2 minutes in air.

[0062] (4) The low-temperature atmospheric pressure plasma surface hydrophilic modification device based on carbon dioxide atmosphere of the present invention, taking PP spunbond non-woven fabric as an example, the contact angle of the film surface to water can be increased from 95 o Reduced to 32 o , successfully achieving hydrophilic modification of the film. Analysis of the functional groups on the film surface using an infrared spectrometer revealed that absorption peaks of hydrophilic groups -OH and CO appeared on the surface of the modified PP spunbond nonwoven fabric.

[0063] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0064] In addition, it should be understood that although this specification is described in terms of embodiments, not every embodiment contains only an independent technical solution. This narrative style of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A low-temperature and normal-pressure plasma surface hydrophilic modification device based on a carbon dioxide atmosphere, characterized in that, The device includes a carbon dioxide supply unit (1), a plasma processing chamber (2) and a conveyor belt (3); The plasma processing chamber (2) includes a generation chamber (21) and a post-reaction chamber (22). A positive electrode (23) and a negative electrode (24) are provided in the generation chamber (21), and the distance between them is 10 mm - 500 mm. The positive electrode (23) is electrically connected to an external control power supply, and the negative electrode (24) is grounded. Air blowers (25) are installed at the lower left corner of the generation chamber (21) and the upper right corner of the post-reaction chamber (22); An inlet (26) is provided at the upper left corner of the generation chamber (21), and an outlet (27) is provided at the upper right corner of the post-reaction chamber (22); The surface of the thin film to be processed is activated in the discharge environment when passing through the generation chamber, and the processed thin film reacts fully with the carbon dioxide gas filling the processing chamber during the process of passing through the post-reaction chamber to achieve full reaction; The carbon dioxide supply unit (1) is located at the top of the plasma processing chamber (2). A gas pipe (11) is connected to the bottom of the carbon dioxide supply unit (1), and the gas pipe (11) extends to the bottom inside the generation chamber (21). A control switch (12) is provided at the connection between the carbon dioxide supply unit (1) and the gas pipe (11), and the control switch is electrically connected to a pressure sensor (13). The pressure sensor (13) is located at the top inside the generation chamber (21); The conveyor belt (3) is of a U-shaped structure. The conveyor belt (3) enters the generation chamber (21) from the inlet (26) and leaves the post-reaction chamber (22) from the outlet (27). Sealing structures are provided at both the inlet (26) and the outlet (27), and the sealing structures are two elastic silicone sheets arranged in the same direction; The positive electrode (23) is located above the conveyor belt (3), and the negative electrode (24) is located below the conveyor belt (3). The conveyor belt (3) is embedded between the positive electrode (23) and the negative electrode (24). The negative electrode (24) consists of at least two conveyor rollers, and the rotation of the conveyor rollers drives the movement of the conveyor belt (3). The thin film to be processed adheres to the surface of the conveyor belt (3).

2. The hydrophilic surface modification device based on low-temperature and normal-pressure plasma in a carbon dioxide atmosphere according to claim 1, characterized in that, The positive electrode (23) is a rod-shaped or tubular electrode made of one of the highly conductive metals iron, copper, or silver. The negative electrode (24) is made of stainless steel, and an insulating coating is attached to the surface of the negative electrode (24). The material of the insulating coating is Al2O3 or Ca 0.8 Sr 0.2 TiO3.

3. A method for hydrophilic surface modification by low-temperature and atmospheric-pressure plasma based on carbon dioxide atmosphere, characterized in that, Using the device according to any one of claims 1 - 2, the method includes the following steps: S1: Attach the thin film to be processed to the conveyor belt (3); S2: Turn on the control switch, and the carbon dioxide in the carbon dioxide supply unit (1) enters the generation chamber (21) until the pressure sensor (13) detects that the air pressure in the generation chamber (21) is equal to one atmosphere; S3: Turn on the control power switch, the positive electrode starts to discharge, rotate the conveyor rollers, and the conveyor rollers drive the movement of the conveyor belt (3). The thin film to be processed attached to the surface of the conveyor belt (3) passes through the generation chamber (21) and the post-reaction chamber (22) in sequence.

4. The method for hydrophilic modification of the surface by low-temperature and atmospheric-pressure plasma based on a carbon dioxide atmosphere according to claim 3, characterized in that, The operating power of the control power supply is 50 W - 50 kW; The discharge frequency of the positive electrode (23) is 10 kHz - 100 MHz; The operating time of the thin film to be processed in the generation chamber (21) is 3 - 5 min, and the operating time in the post-reaction chamber (22) is 1 - 3 min.

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