CN115403813A

CN115403813A - Polytetrafluoroethylene surface hydrophilization modification method

Info

Publication number: CN115403813A
Application number: CN202210890915.9A
Authority: CN
Inventors: 陈发泽; 刘文超; 杨振; 田延岭; 张大卫
Original assignee: Tianjin University
Current assignee: Tianjin University
Priority date: 2022-07-27
Filing date: 2022-07-27
Publication date: 2022-11-29

Abstract

The invention belongs to the technical field of material surface treatment, and particularly relates to a polytetrafluoroethylene surface hydrophilization modification method, which comprises the following steps of processing the surface of a polytetrafluoroethylene sample to form a microstructure; step two, ultrasonically cleaning the processed polytetrafluoroethylene sample wafer, drying and placing on a workbench; and step three, carrying out surface treatment modification on the polytetrafluoroethylene sample wafer by using plasma jet, and then washing and drying the polytetrafluoroethylene sample wafer by using deionized water. According to the invention, the processing method is optimized, so that the modification effect of the polytetrafluoroethylene can be improved.

Description

Polytetrafluoroethylene surface hydrophilization modification method

Technical Field

The invention belongs to the technical field of material surface treatment, and particularly relates to a hydrophilic modification method for a polytetrafluoroethylene surface.

Background

Polytetrafluoroethylene (Polytetrafluoroethylene) has the advantages of good insulating property, high chemical stability, self-lubrication, low water absorption, good weather resistance and the like, and becomes one of the most important engineering plastics in the fields of national defense and military, aerospace, mechanical engineering, petrochemical engineering, biomedicine and the like. Such as high-frequency high-speed copper-clad plates in 5G communication, dynamic sealing parts of aircraft engines and the like. However, polytetrafluoroethylene is intrinsically hydrophobic and is a typical material difficult to bond, so that the surface of the polytetrafluoroethylene is subjected to hydrophilic modification to improve the bonding performance of the polytetrafluoroethylene, and the polytetrafluoroethylene has very important significance. To date, much research has been conducted on the surface hydrophilization modification and adhesion improvement of polytetrafluoroethylene, and this can be achieved by etching (i.e., introducing a coarse structure) and oxidizing (i.e., introducing a hydrophilic oxygen-containing group) the polytetrafluoroethylene surface.

At present, the commonly used modification methods include wet chemical method, plasma method, radiation grafting method, ion beam irradiation and the like. The sodium-naphthalene solution is adopted to treat the polytetrafluoroethylene, a carbonization layer and polar groups such as-OH and-COOH are formed on the surface of the polytetrafluoroethylene, so that the water contact angle of the surface of a sample is reduced from 110 degrees to 22 degrees, and the shear strength of the sample is improved by more than 90 times (3.564 MPa) after the sample is bonded with stainless steel by using epoxy glue, but the method has poor process controllability and serious environmental pollution. The invention patent with publication number CN113318606A modifies polytetrafluoroethylene by means of combining an impregnation method and a pressurization method, but the modification process of the method is complex and the operation is complicated. The surface of the polytetrafluoroethylene is treated by using low-pressure microwave NH3 plasma, and after 15 seconds of treatment, the adhesive strength of the polytetrafluoroethylene and the epoxy resin adhesive is from 0.2N/mm ² Increase to 3.5N/mm ² However, this process is carried out under low pressure conditions, which increases the processing cost and limits the efficiency of the process.

The methods can realize hydrophilic modification and improvement of the adhesive property on the surface of the polytetrafluoroethylene, but the methods have limited effect on the surface roughness of the polytetrafluoroethylene, and the hydrophilicity and the adhesive property of the modified surface are difficult to greatly improve.

Disclosure of Invention

The invention aims to: aiming at the defects of the prior art, the method for modifying the surface of the polytetrafluoroethylene through hydrophilization is provided, and the modification effect of the polytetrafluoroethylene can be improved through optimizing the processing method.

In order to achieve the purpose, the invention adopts the following technical scheme:

a hydrophilic modification method for polytetrafluoroethylene surfaces comprises the following steps: step one, processing the surface of a polytetrafluoroethylene sample wafer to form a microstructure; step two, ultrasonically cleaning the processed polytetrafluoroethylene sample wafer, drying and placing on a workbench; and step three, carrying out surface treatment modification on the polytetrafluoroethylene sample wafer by using plasma jet, and then washing and drying the polytetrafluoroethylene sample wafer by using deionized water.

Preferably, in the first step, the microstructure is a latticed micro-roughness structure.

Preferably, in the first step, femtosecond laser processing is adopted, the power range of the femtosecond laser is 1.2W-4.2W, and the scanning distance of the femtosecond laser is 10 μm-100 μm.

Preferably, in the third step, a radio frequency dielectric barrier discharge device is used to generate the plasma jet.

The modified polytetrafluoroethylene sample wafer has the beneficial effects that the surface wettability of the modified polytetrafluoroethylene sample wafer is obviously improved, and the specific expression is that the water contact angle of the surfaces of two modified polytetrafluoroethylene sample wafers is obviously reduced by using femtosecond laser micromachining for assistance. The modified polytetrafluoroethylene surface bonding performance is obviously enhanced, and the bonding strength obtained by a shear-stretch experiment and a T-type stripping experiment performed after the polytetrafluoroethylene and the copper sheet are bonded by using epoxy resin glue is obviously improved. The invention utilizes the normal pressure plasma for processing, and the experimental equipment has simple structure, convenient operation and no pollution in the modification process.

Drawings

Features, advantages and technical effects of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of a modification process of the present invention.

FIG. 2 is a graph showing a comparison of water contact angles of modified polytetrafluoroethylene according to the invention.

FIG. 3 is a graph comparing shear strength and bond strength of modified polytetrafluoroethylene of the invention.

Detailed Description

As used in the specification and in the claims, certain terms are used to refer to particular components. As one skilled in the art will appreciate, manufacturers may refer to a component by different names. This specification and claims do not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to. "substantially" means within an acceptable error range, and a person skilled in the art can solve the technical problem within a certain error range to substantially achieve the technical effect.

Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

The present invention will be described in further detail with reference to fig. 1 to 3, but the present invention is not limited thereto.

A method for hydrophilizing and modifying the surface of polytetrafluoroethylene comprises the following steps:

step one, processing the surface of a polytetrafluoroethylene sample wafer to form a microstructure;

step two, ultrasonically cleaning the processed polytetrafluoroethylene sample wafer, drying and placing on a workbench;

and step three, carrying out surface treatment modification on the polytetrafluoroethylene sample wafer by using plasma jet, and then washing and drying the polytetrafluoroethylene sample wafer by using deionized water.

In the hydrophilization modification method for the polytetrafluoroethylene surface, in the first step, the microstructure is a latticed micro-roughness structure.

In the method for hydrophilizing and modifying the surface of the polytetrafluoroethylene, in the first step, femtosecond laser processing is adopted, the power range of the femtosecond laser is 1.2W-4.2W, and the scanning distance of the femtosecond laser is 10 mu m-100 mu m.

In the hydrophilization modification method for the polytetrafluoroethylene surface, step three, he plasma jet generated by a radio frequency Dielectric Barrier Discharge (DBD) device is adopted.

Example 1

1. Cutting a polytetrafluoroethylene sample into blocks with the size of 2cm multiplied by 2cm, and ultrasonically cleaning for 5 minutes by using deionized water;

2. scanning a grid with a pitch of 40 μm at a speed of 100mm/s with a 4.2W laser;

3. ultrasonically cleaning the processed polytetrafluoroethylene sample wafer for 5 minutes by using deionized water;

4. placing a cleaned sample wafer on a workbench, directly modifying the He plasma jet generated by the DBD, wherein the distance between the sample wafer and a jet nozzle is 3-5mm, the voltage reading of a transformer is 22v, the flow rate of helium is 3L/min, and the modification time is 2min;

5. and cleaning the modified sample wafer by using deionized water after the completion, and drying at room temperature.

Example 2

4. carrying out graft polymerization pretreatment on the cleaned sample wafer for 1min by using He plasma to activate the surface of the polytetrafluoroethylene sample wafer;

5. placing the activated polytetrafluoroethylene sample wafer in the air for 5min to generate active sites on the surface of the sample wafer so as to facilitate graft polymerization;

6. placing the activated polytetrafluoroethylene sample wafer in an acrylic acid solution with the concentration of 40%, and carrying out graft polymerization for 4h at the temperature of 60 ℃;

7. and cleaning the sample wafer subjected to graft polymerization by using deionized water.

Control 1

2. placing a cleaned sample wafer on a workbench, directly modifying the He plasma jet generated by the DBD, wherein the distance between the sample wafer and a jet nozzle is 3-5mm, the voltage reading of a transformer is 22v, the flow rate of helium is 3L/min, and the modification time is 2min;

3. and cleaning the modified sample wafer by using deionized water after the completion, and drying at room temperature.

Control 2

2. carrying out graft polymerization pretreatment on the cleaned sample wafer for 1min by using He plasma to activate the surface of the polytetrafluoroethylene sample wafer;

3. placing the activated polytetrafluoroethylene sample wafer in the air for 5min to generate active sites on the surface of the sample wafer so as to facilitate graft polymerization;

4. placing the activated polytetrafluoroethylene sample wafer in an acrylic acid solution with the concentration of 40%, and carrying out graft polymerization for 4h at the temperature of 60 ℃;

5. and cleaning the sample wafer subjected to graft polymerization by using deionized water.

And (3) detecting a modification result:

1. the sample pieces of the above examples 1 to 2 and controls 1 to 2 were subjected to measurement of the contact angle of the surface after modification by the pendant drop method using a contact angle measuring instrument;

2. samples of the above examples 1 to 2 and controls 1 to 2 were taken, and samples for shear tensile test and T-peel test were prepared in accordance with GB/T7124-2008 and GB/T2791-1995, and adhesion strength was measured using a tensile tester.

FIG. 2 shows the contact angle measurement data after modification of PTFE, which is 98 ℃ before modification and 56 ℃ after modification in the control group 1. Control 2 had a 100 ° before modification and a 45 ° after modification. The latter two groups of data are contact angle data of modified polytetrafluoroethylene by femtosecond laser micromachining assisted plasma, the contact angle is 150 degrees after laser machining, the machined sample wafer is respectively subjected to He plasma direct modification and plasma induced graft polymerization modification, and the contact angles are reduced to 31 degrees and 23 degrees. The modification method can improve the modification effect of the polytetrafluoroethylene.

Fig. 3 shows adhesion strength test data, (1) shear tensile test data, and (2) T-type peel test data, according to which it is found that the effect of a sample wafer with a microstructure processed by laser is significantly improved, the shear strength can be up to 2.57MPa, and the highest energy of a sample wafer without a microstructure processed by laser can be up to 1.56MPa, and meanwhile, the data of the T-type peel test is more obvious, and the adhesion strength of a sample wafer with a microstructure processed by laser can be up to 6216N/m, and the highest position of a sample wafer without a microstructure processed by laser is 887N/m. It can be shown that the method of the invention can improve the bonding property of the modified polytetrafluoroethylene.

Variations and modifications to the above-described embodiments may also occur to those skilled in the art, which fall within the scope of the invention as disclosed and taught herein. Therefore, the present invention is not limited to the above-mentioned embodiments, and any obvious improvement, replacement or modification made by those skilled in the art based on the present invention is within the protection scope of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. A method for hydrophilizing and modifying a polytetrafluoroethylene surface, comprising:

2. The method for modifying the surface hydrophilization of polytetrafluoroethylene according to claim 1, wherein: in the first step, the microstructure is a latticed micron rough structure.

3. The method for modifying the surface hydrophilization of polytetrafluoroethylene according to claim 1, wherein: in the first step, femtosecond laser processing is adopted, the power range of the femtosecond laser is 1.2W-4.2W, and the scanning interval of the femtosecond laser is 10 mu m-100 mu m.

4. The method for modifying the surface hydrophilization of polytetrafluoroethylene according to claim 1, wherein: in the third step, a radio frequency dielectric barrier discharge device is adopted to generate plasma jet.