CN116922749A - Method for enhancing surface adhesion performance of polytetrafluoroethylene material - Google Patents

Abstract

The invention discloses a method for enhancing the surface bonding performance of polytetrafluoroethylene materials, which relates to the technical field of surface treatment technology and includes the following steps: corona treatment on the surface of the PTFE material to obtain a semi-finished product A; coating the surface of the semi-finished product A with adhesive Grafting solution, the grafting solution contains at least one polar vinyl monomer to obtain semi-finished product B; cover the surface of semi-finished product B with an isolation layer, and then perform low-energy electron beam irradiation in an inert atmosphere to obtain semi-finished product C; remove semi-finished product C For the isolation layer on the surface, use deionized water to wash away the residual polar vinyl monomer and dry it. This method is used to improve the surface adhesion properties of polytetrafluoroethylene films or plates. It has the advantages of high efficiency, environmental protection, cheapness, stable processing effect, and no damage to the properties of the material itself. It can solve the existing high-energy radiation graft modification This method leads to the problem of reduced performance of polytetrafluoroethylene materials.

Description

A method to enhance the surface bonding performance of polytetrafluoroethylene materials

Technical field

The present invention relates to the technical field of surface treatment technology, specifically a method for enhancing the surface bonding performance of polytetrafluoroethylene materials.

Background technique

Polytetrafluoroethylene (PTFE) is known as the "King of Plastics" because of its low friction coefficient, excellent aging resistance, excellent chemical stability, minimal water absorption, excellent electrical insulation, and wide range of applications. Temperature, outstanding surface non-stickiness and good self-lubricating properties, excellent thermal stability and many other excellent properties, it is widely used in aerospace, national defense armaments, petrochemical industry, electronic appliances, transportation, machinery, energy, construction, Textiles, food, medicine and many other fields have become indispensable materials for solving many key technologies and improving production technology levels in modern science and technology, military industry and civilian use. In practical applications, PTFE is often compounded with a variety of materials, but Due to the extremely low surface energy of PTFE and poor surface wetting properties, almost all adhesives cannot adhere to its surface, which limits the application of PEFE. For this reason, it is urgent to solve its surface problems, improve its surface activity, and enhance the bonding between PTFE and PTFE. The interface affinity of other materials enables its diversified applications.

In terms of improving the adhesion of PTFE, the treatment methods that have been used mainly include: sodium-naphthalene complex chemical modification method, high-temperature melting method, excimer laser treatment method, plasma modification method, and high-energy radiation graft modification method etc., but these methods all have corresponding shortcomings. The surface of PTFE treated with sodium-naphthalene complex becomes obviously darker and black, which affects the appearance of the material. The surface resistivity of treated PTFE decreases at high temperatures and is exposed to sunlight for a long time. The bonding performance of the material will be seriously reduced, and the treatment process will produce a large amount of harmful waste liquid, which will not only seriously pollute the environment, but also increase the company's processing costs. It is not in line with the current environmental protection policy. The advantage of the high-temperature melting method is that it has better weather resistance and moisture and heat resistance than other methods. The method is remarkable and suitable for long-term outdoor use. The disadvantage is that PTFE releases a toxic substance during high-temperature sintering, and the shape of the PTFE film is not easy to maintain. The advantage of the excimer laser treatment method is that the durability of the modified PTFE surface is better. The PTFE surface can be selectively modified as needed, avoiding the blindness of the chemical modification method and having good practical value. However, this method has strict requirements on the laser source used, and the oscillation wavelength of the laser beam must be able to To be absorbed by PTFE, the photon energy of the laser beam must be greater than the C-F bond energy in PTFE. The plasma modification method has the disadvantages of expensive processing equipment and short-lasting post-treatment effects. The high-energy radiation graft modification method has The main advantages are that the operation is simple, clean and fast, the grafting rate is easy to control, and no initiators and catalysts are needed. The main disadvantage is that polytetrafluoroethylene is a typical radiation-degradable polymer with poor radiation resistance and is susceptible to high-energy radiation. It is easy to cause degradation later.

The modified PTFE surface will lose its smoothness, and the PTFE matrix will be degraded during radiation grafting, resulting in a significant decrease in its mechanical properties. Therefore, it is necessary to develop an efficient, environmentally friendly, cheap, stable treatment effect, and does not damage the material. The surface modification process of PTFE with bulk properties is an important challenge to improve the performance of PTFE.

Contents of the invention

The purpose of this invention is to provide a method for enhancing the surface bonding performance of polytetrafluoroethylene materials, a PTFE surface treatment method that is efficient, environmentally friendly, cheap, has stable processing effects, and does not destroy the performance of the material itself, so as to solve the problems in the existing technology. problems.

The technical solutions adopted by the present invention are as follows:

A method for enhancing the surface bonding performance of polytetrafluoroethylene materials, including the following steps:

1) Perform corona treatment on the surface of the PTFE material to obtain semi-finished product A;

2) Coating the surface of semi-finished product A with a grafting solution containing at least one polar vinyl monomer to obtain semi-finished product B;

3) Cover the surface of semi-finished product B with an isolation layer, and then perform low-energy electron beam irradiation in an inert atmosphere to obtain semi-finished product C;

4) Remove the isolation layer on the surface of semi-finished product C, use deionized water to wash away the residual polar vinyl monomer, and dry it.

Preferably, in step 1), the corona treatment power is 2kW~4kW, and the treatment time is 2~10s.

Preferably, in step 2), the grafting solution contains 30% to 50% polar vinyl monomer, 2% to 5% tackifier, 0.2% to 2% wetting agent in terms of mass ratio. The remainder is water.

Preferably, in step 3), the isolation layer includes any one of polyester film and polyamide film, and the thickness of the isolation layer is 5-20 μm.

Preferably, in step 3), the dose of low-energy electron beam irradiation is 5-30KGy.

Preferably, in step 4), the temperature of the deionized water is 50-80°C, and the drying temperature is 100-120°C.

Preferably, the polar vinyl monomer is acrylic acid, methacrylic acid, maleic acid, etaconic acid, sodium styrene sulfonate, sodium vinyl sulfonate, allyl sulfonic acid, and allyl sulfonate. , acrylonitrile, vinylpyridine, vinylpyrrolidone.

Preferably, the tackifier is one or more of polyacrylamide, polyvinyl alcohol, polyvinylpyrrolidone, polyoxyethylene, and sodium carboxymethyl cellulose; the wetting agent is alkylphenol polyoxyethylene. One or more of vinyl ether, alkyl alcohol polyoxyethylene ether, polyoxypropylene ether, alkyl benzene sulfonate.

In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are:

(1) The present invention adopts a low-energy electron beam co-radiation grafting method, which keeps polytetrafluoroethylene in contact with polar vinyl monomers while conducting electron beams, so that the free radicals generated by radiation can initiate a grafting reaction once they are generated. The energy range of beam radiation is between 80 and 160keV. Its radiation degradation effect on the polytetrafluoroethylene material is limited to the surface, which is very beneficial to protecting the mechanical strength of the matrix material. Compared with the existing pre-radiation grafting technology, the use of radiation The rate is higher, the dose required is low, and the degradation of the material is avoided, and the impact on the mechanical properties of the material is much less than that of the high-energy radiation grafting modification method;

(2) Since polytetrafluoroethylene remains in contact with polar vinyl monomers during the irradiation process, further grafting reactions will occur on the graft chain, and the relationship between the graft chain and the grafted polymer molecules will occur. Cross-linking can improve grafting rate and bonding performance;

(3) Corona treatment was performed before grafting, using high-frequency and high-voltage corona discharge on the surface of the treated polymer to generate low-temperature plasma and penetrate into the surface of the polymer to destroy its molecular structure through electric shock and penetration. Then, the treated surface molecules are oxidized and polarized, and the wettability and surface adhesion of the surface to polar solvents are increased, which can produce stronger adhesion on the polytetrafluoroethylene surface;

(4) By covering the surface of polytetrafluoroethylene with an isolation layer, the polymerization inhibitory effect of oxygen can be reduced or eliminated as much as possible.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be further described in detail below in conjunction with the examples. It should be understood that the specific embodiments described here are only used to explain the present invention and are not intended to limit the present invention. .

The invention provides a method for enhancing the surface bonding performance of polytetrafluoroethylene materials, which includes the following steps:

1) Perform corona treatment on the surface of the polytetrafluoroethylene material with a treatment power of 2kW to 4kW and a treatment time of 2 to 10s to obtain semi-finished product A;

2) Coat the surface of semi-finished product A with a grafting solution to obtain semi-finished product B. In terms of mass ratio, the grafting solution contains 30% to 50% of polar vinyl monomer, 2 to 5% of tackifier, 0.2 to 2% wetting agent, the balance is water, the polar vinyl monomers are acrylic acid, methacrylic acid, maleic acid, etaconic acid, sodium styrene sulfonate, sodium vinyl sulfonate, allyl sulfonic acid , any one or more of allyl sulfonate, acryl cyanide, vinyl pyridine, vinyl pyrrolidone;

3) Cover the surface of semi-finished product B with an isolation layer, and then use low-energy electron beam (80keV-160keV) for low-energy electron beam irradiation in an inert atmosphere. The irradiation dose is 5-30KGy to obtain semi-finished product C;

4) Remove the isolation layer on the surface of semi-finished product C, use deionized water at 50-80°C to wash away the residual polar vinyl monomer, and use a constant temperature drying oven to dry at 100-120°C until the weight no longer changes.

Example 1

Process the PTFE membrane according to the above-mentioned method of enhancing the surface bonding performance of polytetrafluoroethylene materials. The specific process is as follows:

1) Prepare grafting solution: Prepare an aqueous solution of vinyl monomers with mass percentages of 30% acrylic acid, 2% sodium carboxymethylcellulose, 0.5% alkylphenol polyoxyethylene ether, and 67.5% water as the grafting solution;

2) Take the PTFE film and use a corona treatment machine to corona treat its surface with a power of 4kW and a treatment time of 2 seconds;

3) Coat the surface of the corona-treated PTFE membrane with the grafting solution prepared in 1), with a coating amount of 10g/m ² ;

4) Use an isolation layer to cover the PTFE membrane coated with the grafting solution. The isolation layer is made of polyester film with a thickness of 10 μm. Then unfold the PTFE membrane in the area under the beam of the electron curtain accelerator, evacuate and fill it with inert gases such as nitrogen. Then perform low-energy electron beam irradiation with a dose of 20KGy;

5) Remove the isolation layer and clean it with 70°C deionized water until the homopolymer and unreacted polar vinyl monomer are cleaned, and then place it in a constant temperature drying oven at 100°C to dry until the PTFE membrane is The weight no longer changes.

Conduct index testing on the dried PTFE membrane obtained in step 5), and use the PTFE membrane before irradiation as a blank example and the PTFE membrane after irradiation by high-energy radiation grafting modification as a comparison example to compare its various indicators. , the results are shown in the table below:

Table 1 PTFE membrane index test data after treatment in Example 1

As can be seen from the above table, the water contact angle on the surface of the PTFE membrane modified by the method of the present invention is significantly reduced, from 120° to 60°. At the same time, the tensile strength does not decrease significantly. The 90° peel strength of the transparent tape is reduced from 0.229kN/m. The increase to 0.580kN/m shows that the bonding performance of the PTFE membrane produced by the method of the present invention is significantly improved and has little impact on the tensile strength of the PTFE membrane, both of which are better than those of the comparative example.

Examples 2 to 23

On the basis of Example 1, according to the above-mentioned method of enhancing the surface bonding performance of polytetrafluoroethylene materials, the composition and treatment conditions of the grafting solution were changed, and Examples 2 to 23 were obtained as follows:

Table 2 Processing conditions of Examples 2 to 13

The PTFE membranes obtained in Examples 2 to 23 were subjected to index tests, and the results are shown in Table 3 below:

Table 3 Test data of Examples 2 to 23

As shown in Table 3 above, Example 23 has the best bonding performance. The 90° peel strength of the transparent tapes of Examples 2 to 23 are all better than those of the blank example, and the tensile strength decreases by no more than 10%. This affects the mechanical properties of the PTFE material. smaller.

In addition to Examples 1 to 23, the polar vinyl monomer can also be etaconic acid, sodium styrene sulfonate, sodium vinyl sulfonate, allyl sulfonic acid, allyl sulfonate, acryl cyanide, ethylene The tackifier can also be one or more of polyvinyl alcohol, polyvinylpyrrolidone, and polyoxyethylene. The wetting agent can also be polyoxypropylene ether, alkyl benzene sulfonate. After testing, the differences in various indicators between the obtained PTFE membrane and Examples 1 to 23 are within the expected range of those skilled in the art, and will not be described again here.

The above descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (8)

1. A method for enhancing the surface bonding performance of polytetrafluoroethylene materials, which is characterized in that it includes the following steps: 1) Perform corona treatment on the surface of the PTFE material to obtain semi-finished product A; 2) Coating the surface of semi-finished product A with a grafting solution containing at least one polar vinyl monomer to obtain semi-finished product B; 3) Cover the surface of semi-finished product B with an isolation layer, and then perform low-energy electron beam irradiation in an inert atmosphere to obtain semi-finished product C; 4) Remove the isolation layer on the surface of semi-finished product C, use deionized water to wash away the residual polar vinyl monomer, and dry it. 2. A method for enhancing the surface bonding performance of polytetrafluoroethylene materials according to claim 1, characterized in that in step 1), the corona treatment power is 2kW~4kW, and the treatment time is 2~10s. 3. A method for enhancing the surface bonding performance of polytetrafluoroethylene materials according to claim 1, characterized in that in step 2), the grafting solution contains 30% to 50% by mass ratio. Polar vinyl monomer, 2-5% tackifier, 0.2-2% wetting agent, and the balance is water. 4. A method for enhancing the surface bonding performance of polytetrafluoroethylene materials according to claim 1, characterized in that in step 3), the isolation layer includes any one of polyester film and polyamide film. , the thickness of the isolation layer is 5-20 μm. 5. A method for enhancing the surface bonding performance of polytetrafluoroethylene materials according to claim 1, characterized in that in step 3), the energy range of low-energy electron beam irradiation is 80~160keV, and the dose is 5~ 30KGy. 6. A method for enhancing the surface bonding performance of polytetrafluoroethylene materials according to claim 1, characterized in that in step 4), the temperature of the deionized water is 50-80°C, and the drying temperature is 100-100°C. 120℃. 7. A method for enhancing the surface bonding performance of polytetrafluoroethylene materials according to claim 2 or 3, characterized in that the polar vinyl monomer is acrylic acid, methacrylic acid, maleic acid, ethylene Conic acid, sodium styrene sulfonate, sodium vinyl sulfonate, allyl sulfonic acid, allyl sulfonate, acryl cyanide, vinyl pyridine, vinyl pyrrolidone. 8. A method for enhancing the surface bonding performance of polytetrafluoroethylene materials according to claim 3, characterized in that the tackifier is polyacrylamide, polyvinyl alcohol, polyvinylpyrrolidone, polyoxyethylene, One or more of sodium carboxymethyl cellulose; the wetting agent is one of alkylphenol polyoxyethylene ether, alkyl alcohol polyoxyethylene ether, polyoxypropylene ether, and alkyl benzene sulfonate. species or several species.