TW202206497A - A fluorine-containing dispersion and its preparation method, a fluorine-containing composite membrane and its application - Google Patents

Abstract

A fluorine-containing dispersion and its preparation method, a fluorine-containing composite membrane and its application. The solid components of the fluorine-containing dispersion include fluorine-containing polymer powder and polyimide. The particle size of fluorine-containing polymer powder is less than or equal to 3 μm, the weight percentage of fluorine-containing polymer powder in the solid component of fluorine-containing dispersion is greater than or equal to 85%. The weight percentage of polyimide in the solid component of fluorine-containing dispersion is less than or equal to 15%. In addition, the invention also provides a preparation method of the fluorine-containing dispersion solution, a fluorine-containing composite membrane and its application.

Description

Fluorine-containing dispersion liquid and preparation method thereof, fluorine-containing composite membrane and application thereof

The invention relates to the technical field of polymer film preparation, in particular to a preparation method of a fluorine-containing dispersion liquid, a fluorine-containing composite membrane and applications thereof.

The traditional release film or release paper is not resistant to high temperature, and will shrink and lose its release ability under high temperature environment. Therefore, it is not suitable for high temperature process or coating film formation process containing high boiling point solvents, such as polyimide The production process of the film cannot use the traditional release film or release paper.

At present, the preparation of the polyimide film requires the use of a steel strip for coating operations. The specific method includes: coating the polyimide solution on the steel strip and baking it to obtain a polyimide film roll, and then applying the It is aged in a high temperature cyclization furnace, and the polyamide film is fixed with clamps on both sides, and the transverse (TD) and longitudinal (MD) stretches are carried out at the same time. During the stretching process, the key parameters that need to be controlled include the tensile strength, mechanical strength, thickness, shrinkage force generated by aging and the need to ensure that the difference between the longitudinal (MD) and transverse (TD) mechanical strengths of the polyamide film is not too large. , resulting in a high process limit threshold for polyimide films. At the same time, the traditional stretching process is not suitable for thermoplastic polyimide formulations, because the polyimide film will collapse and stick to the fixture at high temperature. Therefore, the preparation method of traditional polyimide film is limited. The choice of polyamide solution formulation was discussed.

In order to solve the above-mentioned technical problems, the present invention proposes a fluorine-containing dispersion liquid and a preparation method thereof, a fluorine-containing composite film and an application thereof. For polymer films such as imide films or polyester films, the embodiments of the present invention will be described by taking a fluorine-containing composite film to prepare a polyimide film as an example.

The present invention provides a fluorine-containing dispersion liquid. The solid content of the fluorine-containing dispersion liquid includes a fluorine-containing polymer powder and a polyimide. The particle size of the fluorine-containing polymer powder is less than or equal to 3 μm. The weight percentage of the fluorine polymer powder in the solid content of the fluorine-containing dispersion is greater than or equal to 85%, and the weight percentage of the polyimide in the solid content of the fluorine-containing dispersion is less than or equal to 15% .

Further, the solid content of the fluorine-containing dispersion liquid is 40 wt % to 50 wt %.

Further, the fluorine-containing polymer powder includes one or more of polytetrafluoroethylene, perfluoroalkoxy, polyperfluoroethylene propylene, trifluorochloroethylene, ethylene-trifluorochloroethylene and polyperfluoroethylene vinylene. several.

The present invention also provides a method for preparing a fluorine-containing dispersion, comprising the following steps:

A first mixed solution is provided, the first mixed solution includes fluorine-containing polymer powder, and the average particle size of the fluorine-containing polymer powder is less than or equal to 3 μm.

A polyimide solution is added to the first mixed solution, and mixed to obtain the fluorine-containing dispersion.

The polyimide solution includes polyimide, the fluorine-containing polymer powder and the polyimide constitute the solid content of the fluorine-containing dispersion, and the fluorine-containing polymer powder is in the The weight percentage in the solid content of the fluorine-containing dispersion is greater than or equal to 85%, and the weight percentage of the polyimide in the solid content of the fluorine-containing dispersion is less than or equal to 15%.

Further, the solid content of the fluorine-containing dispersion liquid is 40 wt % to 50 wt %.

Further, the fluorine-containing polymer powder includes one or more of polytetrafluoroethylene, perfluoroalkoxy, polyperfluoroethylene propylene, trifluorochloroethylene, ethylene-trifluorochloroethylene and polyperfluoroethylene vinylene. several.

The present invention also provides a fluorine-containing composite membrane, comprising a substrate and a fluorine-containing membrane disposed on at least one surface of the substrate, wherein the fluorine-containing membrane is prepared by heating the above-mentioned fluorine-containing dispersion.

Further, the base material is a polyimide film, and the thickness of the base material is 125 μm˜225 μm.

Further, the thickness of the fluorine-containing film is 3 μm˜6 μm.

Further, the fluorine-containing composite film includes fluorine-containing polymer powder and polybenzoxazole, and the weight percentage of the fluorine-containing polymer powder in the fluorine-containing composite film is greater than or equal to 85%, and the polyphenylene The weight percentage of oxazole in the fluorine-containing composite membrane is less than or equal to 15%.

The present invention also provides a preparation method of the fluorine-containing composite membrane, comprising the following steps:

A substrate is provided.

The above-mentioned fluorine-containing dispersion is coated on at least one surface of the substrate and dried to obtain an intermediate.

The intermediate body is sintered at 400° C. to 450° C. to obtain the fluorine-containing composite film.

The present invention also provides a preparation method of the polymer film, comprising the following steps:

A polymer solution and a fluorine-containing composite membrane as described above are provided.

The polymer solution is coated on the surface of the fluorine-containing film away from the substrate and baked to form an intermediate film layer.

The intermediate film layer is aged to form the polymer film.

Further, the curing comprises the following steps:

The intermediate film layer and the fluorine-containing composite film are wound so that the film layer faces outward to obtain a semi-finished film roll.

The semi-finished film roll is heated and aged under a nitrogen atmosphere to form the polymer film.

The polymer film and the fluorine-containing composite film are respectively wound up.

Further, the curing comprises the following steps:

The intermediate film layer and the fluorine-containing composite film are heated in a nitrogen atmosphere by a suspended RTR process for online aging, so as to form the polymer film.

The polymer film and the fluorine-containing composite film are respectively wound up.

Compared with the prior art, the beneficial effect of the present invention is: due to the existence of polybenzoxazole in the fluorine-containing composite film, high temperature resistance is maintained, so that the fluorine-containing composite film still has release force under high temperature conditions, which is suitable for high temperature. Process or coating and film-forming process containing high boiling point solvent; by adjusting the ratio of fluorine-containing polymer powder and polybenzoxazole, the release force of the fluorine-containing composite film can be adjusted, which is suitable for different release forces. Various polymer solutions are required to form films, which improves the formulation selectivity of polymer solutions; fluorine-containing composite films can realize double-sided release, which is suitable for traditional batch high-temperature curing in rolls to avoid interlayer sticking during roll curing. At the same time, the double release surface can form a film at the same time, which improves the production efficiency; because the thickness of the polyimide film with the fluorine-containing composite film in the middle layer is thick and has sufficient stiffness and toughness, the fluorine-containing composite film can be used. The film is used as a carrier for direct coating and film-forming process, and can be applied to a suspended online high-temperature curing process to improve production efficiency and reduce curling; fluorine-containing composite film can be used as a carrier for coating and film-forming process, without the need for lateral and The longitudinal stretching process reduces the process threshold; there is no oxygen content limit in the film-forming process, and the fluorine-containing composite film can be recycled multiple times, saving costs and conforming to the trend of environmental protection.

The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some, but not all, embodiments of the present invention. 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.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The names of technical means used in the description of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention.

The embodiments described below and features in the embodiments may be combined with each other without conflict.

The present invention provides a fluorine-containing dispersion liquid, the fluorine-containing dispersion liquid includes a fluorine-containing polymer powder, a first solvent and a polyimide solution, and the particle size of the fluorine-containing polymer powder is less than or equal to 3 μm, The polyimide solution includes polyimide and a second solvent, the fluorine-containing polymer powder and the polyimide constitute the solid content of the fluorine-containing dispersion, and the fluorine-containing polymer powder The weight percentage of the polyimide in the solid content of the fluorine-containing dispersion is greater than or equal to 85%, and the weight percentage of the polyimide in the solid content of the fluorine-containing dispersion is less than or equal to 15%.

In this embodiment, the solid content of the fluorine-containing dispersion liquid is 40 wt % to 50 wt %.

In this embodiment, the fluorine-containing polymer powder includes polytetrafluoroethylene, perfluoroalkoxy, polyperfluoroethylene propylene, trifluorochloroethylene, ethylene-trifluorochloroethylene, and polyperfluoroethylene vinylene. one or more of them.

In this embodiment, the first solvent and the second solvent are both polar solvents, specifically N-methylpyrrolidone (NMP), dimethylacetamide (DMAC), 1,4-butyrolactone (GBL), specifically, in this embodiment, both the first solvent and the second solvent are NMP.

In this embodiment, the fluorine-containing dispersion further includes a surfactant, and the surfactant adopts a traditional surfactant, including but not limited to polyether polyamides, polyethers, polyester polyamides , polycarboxylate sodium salt and other surfactants, the addition of the surfactant can make the fluorine-containing polymer powder uniformly dispersed in the first solvent.

The present invention also provides a method for preparing the above-mentioned fluorine-containing dispersion, which specifically includes the following steps:

In step S1, the first solvent and the surfactant are added into the reaction vessel, and the mixture is stirred to make the two evenly mixed.

In this embodiment, the first solvent is a polar solvent, specifically, N-methylpyrrolidone (NMP).

In this embodiment, the surfactant is a traditional surfactant, including but not limited to polyether polyamides, polyethers, polyester polyamides, and polycarboxylate sodium salts.

In step S2, fluorine-containing polymer powder is added to the mixed solution obtained in step S1, and mixed to obtain a first mixed solution.

Specifically, slowly pour the fluorine-containing polymer powder into the mixed solution obtained in step S1 in batches, stir while pouring, until all is poured, and continue to stir for 0.5h to 24h to make the fluorine-containing polymer powder It is uniformly dispersed in the first solvent containing the surfactant to obtain the first mixed solution.

The fluorine-containing polymer powder includes polytetrafluoroethylene (PTFE), perfluoroalkoxy (PFA), polyperfluoroethylene propylene (FEP), chlorotrifluoroethylene (CTFE), ethylene-chlorotrifluoroethylene ( ECTFE), and one or more of polyperfluorovinylidene (PVDF).

Specifically, in this embodiment, the fluorine-containing polymer powder is perfluoroalkoxy (PFA).

In the present embodiment, the average particle size of the fluorine-containing polymer powder is less than or equal to 3 μm, preferably 0.1 μm to 3 μm.

Step S3, providing a polyimide solution, adding the polyimide solution to the first mixed solution, and mixing to obtain the fluorine-containing dispersion.

The fluorine-containing polymer powder and the polyimide constitute the solid content of the fluorine-containing dispersion, and the weight percentage of the fluorine-containing polymer powder in the solid content of the fluorine-containing dispersion is greater than or equal to 85%, the weight percentage of the polyimide in the solid content of the fluorine-containing dispersion is less than or equal to 15%.

The colloidal weight of the fluorine-containing dispersion includes the weight of polyimide, the weight of PFA powder and the weight of solvent NMP, and the weight percentages of the three are calculated as 100%, wherein polyimide and PFA powder are solid components , the colloidal solid content of the obtained fluorine-containing dispersion liquid is 40 wt % to 50 wt %, and the viscosity is 500 CPS to 1500 CPS.

In this embodiment, the preparation method of the polyimide solution comprises the following steps:

Diamine, dianhydride and NMP solvent were added to the reaction vessel, and the solution was stirred under nitrogen atmosphere for at least 24 hours to obtain a polyamide acid solution.

In this embodiment, the solid content of the polyamic acid solution is 20 wt% to 25 wt%.

In this embodiment, the molar ratio of the diamine to the dianhydride is 1:1.

In this embodiment, the diamine is 2,2-bis(3-amino-4-hydroxyphenyl)hexafluoropropane (6FAP), and the mass of the diamine is 20g-40g, more preferably 24g-34g.

In this embodiment, the dianhydride is 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), and the mass of the dianhydride is 40g-55g.

In the second step, xylene (Xylene) solvent is added to the polyimide solution, and the temperature is raised to 180° C. to carry out a cyclization reaction in a nitrogen environment, and the reaction is performed for 1 h to 6 h to obtain the polyimide solution.

In the present embodiment, the reaction process in the specific polyimide solution preparation method is as follows:

Referring to FIG. 1 , the present invention further provides a fluorine-containing composite film 100 , comprising a substrate 1 and a fluorine-containing film 2 disposed on at least one surface of the substrate 1 . The fluorine-containing dispersion liquid is coated on at least one side of the substrate 1 and then heated.

In this embodiment, the substrate 1 is a polyimide film, and the thickness of the substrate 1 is 125 μm˜225 μm. The thickness of the polyimide film is relatively thick, which can improve the stiffness and toughness of the fluorine-containing composite film 100 .

In this embodiment, the thickness of the fluorine-containing film 2 is 3 μm˜6 μm.

The fluorine-containing film 2 includes the fluorine-containing polymer powder and polybenzoxazole, and the fluorine-containing composite film can be adjusted by adjusting the contents of the fluorine-containing polymer powder and polybenzoxazole. release force. The solid content in the fluorine-containing composite film is fluorine-containing polymer powder and polybenzoxazole, and the weight percentage of the solid content of the fluorine-containing polymer powder in the fluorine-containing composite film is greater than or equal to 85%. The weight percentage of the solid content of polybenzoxazole in the fluorine-containing composite film is less than or equal to 15%. The fluorine-containing polymer powder in the fluorine-containing film 2 will be melted into a melt at high temperature, which is convenient for film formation.

Specifically, the above-mentioned preparation method of the fluorine-containing composite membrane includes the following steps:

In the first step, a polyimide film is provided, and the above-mentioned fluorine-containing dispersion is coated on at least one side of the polyimide film to obtain an intermediate.

In the second step, the above intermediate is baked at a temperature of 140°C to 150°C.

In the third step, the baked intermediate is sintered at a temperature of 400° C. to 450° C. to obtain the fluorine-containing composite film.

Because the polyimide solution is added to the fluorine-containing dispersion liquid, the polyimide solution can be thermally rearranged (TR) at high temperature, and the original imine structure is converted into a benzoxazole structure, And then generate polybenzoxazole, and the reaction process is as follows:

Polybenzoxazole (PBO) is a resin with good thermal and mechanical properties, and chemical resistance. Its structure is similar to polyimide, but its polarity is lower than that of polyimide. The surface of the film has a polybenzoxazole component, which can well adjust the release force of the fluorine-containing composite film, and can better combine with the polyimide film in the middle to improve the adhesion of the fluorine-containing film to the substrate. force.

At the same time, the fluorine-containing polymer powder particles are also melted under high temperature conditions to become a melt, which can better form a homogeneous film.

Because the thickness of the polyimide film in the middle layer is thick and has sufficient stiffness and toughness, the sintering process is directly carried out by a suspended (rollerless) RTR (roll-to-roll) process or a cyclization furnace, which can reduce the curling phenomenon. And there is no oxygen limit during baking, which is in line with the trend of environmental protection. The release force of the fluorine-containing composite film can be changed by adjusting the ratio of PFA powder and polybenzoxazole, thereby increasing the formulation selectivity in the subsequent preparation of the polyimide film. Here, adjusting the ratio of PFA powder and polybenzoxazole can be specifically controlled by adjusting the ratio of PFA powder and polyimide when preparing the fluorine-containing dispersion.

Finally, the fluorine-containing composite film 100 with the fluorine-containing film 2 on one side or the fluorine-containing film 2 on both sides can be prepared. When both sides have a release effect, the film can be coated on both sides to improve the productivity. Solve the problems of interlayer adhesion in the subsequent film preparation process, and the fluorine-containing composite film 100 is a high temperature resistant material (Td> 500 ℃), which can be suitable for high temperature process or coating film formation process containing high boiling point solvent, and there is no need for baking. Oxygen content limit, can be used multiple times, environmental protection and cost saving.

The present invention also provides a preparation method of the polymer film, comprising the following steps:

Step 1, provide a polymer solution and the above-mentioned fluorine-containing composite film 100, the fluorine-containing composite film 100 includes at least one fluorine-containing film 2, and is coated on the surface of the fluorine-containing film 2 away from the substrate 1 The polymer solution is then baked to form an interlayer.

Step 2, curing the intermediate film layer to form the polymer film.

The polymer solution includes, but is not limited to, a polyimide solution, a polyamide solution, or a polyester solution, etc. Specifically, in this embodiment, a polyamide solution is used as an example for detailed description.

The specific production method of polyimide film can be carried out in the following two ways. The main difference between the two methods is that the curing process will be different. One kind of curing process is to use the traditional batch type whole roll and put it in a high temperature nitrogen environment. Curing; another way is to use a suspended (no roller) RTR oven and a high-temperature cyclization furnace for direct on-line curing. The first method is usually used for the production of single-sided film, and the other method can be double-sided film, and the production efficiency is higher. The polyimide film produced in this way can control the thickness of the polymer film to be thinner, and is suitable for the film formation of brittle or thermoplastic polyimide solutions.

The first method will be described in detail below in conjunction with Figure 2:

First, both sides of the fluorine-containing composite film 100 are fluorine-containing film surfaces, and the fluorine-containing composite film 100 is used as a carrier to coat any of the fluorine-containing film surfaces with a polyamic acid solution, and bake it. A polyamide film 200 is formed on the surface of the fluorine-containing film.

Then, the polyamide film 200 and the fluorine-containing composite film 100 are wound together as a whole to obtain a semi-finished roll film.

The semi-finished roll film is put into an oven at 250°C to 360°C, and nitrogen gas is introduced for curing, so that the polyimide film 200 is cyclized at a high temperature, thereby forming the polyimide film 300 .

The fluorine-containing composite film 100 and the polyimide film 300 are respectively wound on the film tearing machine to obtain the finished polyimide film 300 roll.

When the polyamide film is unrolled and matured in a batch oven, the fluorine-containing composite film is coated with polyamide on one side. Because the fluorine-containing composite film has a release force on both sides, the problem of interlayer adhesion of the roll material is successfully improved, and the High temperature cyclization can be carried out for multiple rolls at a time to improve production efficiency.

The first method will be described in detail below with reference to Figure 3:

First, both sides of the fluorine-containing composite film 100 are fluorine-containing film surfaces, and the fluorine-containing composite film 100 is used as a carrier to coat at least one side of the fluorine-containing composite film 100 with a polyamide solution, and bake bake to form a polyamide film 200 on the surface of the fluorine-containing film.

Then, the fluorine-containing composite film 100 with the polyamide film 200 on one or both sides is cured online in a suspended (no roller) RTR oven in a nitrogen atmosphere at 250°C to 360°C to make the polyamide acid film 200 High temperature cyclization is performed to form the polyimide film 300 .

The polyimide film 300 and the fluorine-containing composite film 100 are respectively wound up to obtain the finished polyimide film 300 roll.

In this way, two rolls of material can be produced at the same time, which increases the production capacity.

Because the fluorine-containing composite film 100 is resistant to high temperature, it is suitable for the film-forming process of polyimide film; the fluorine-containing composite film 100 can realize double-sided release, and is suitable for the traditional batch high-temperature curing in rolls, avoiding the process of roll curing. At the same time, the double release surface can be formed into a film at the same time, which improves the production efficiency; because the polyimide film with the fluorine-containing composite film 100 located in the middle layer is thick and has sufficient stiffness and toughness, it can be The fluorine-containing composite film 100 is used as the carrier to directly carry out the coating and film-forming process, and it can be applied to the suspended online high-temperature curing process, which improves the production efficiency and reduces the curling phenomenon; the fluorine-containing composite film 100 can be used as the carrier for coating. The film manufacturing process does not require horizontal and vertical stretching processes, which lowers the process threshold; there is no oxygen content limit in the film-forming process, and the fluorine-containing composite film 100 can be recycled multiple times, saving costs and conforming to the trend of environmental protection.

The solution of the present application will be further described below with specific examples.

Synthesis Example 1

In a 500ml reaction flask, add diamine (6FAP 33.89g) and dianhydride (6FDA 41.11g), wherein the molar ratio of diamine and dianhydride is 1:1, solvent NMP (225g), wherein the solid content is 20wt% ~ 25wt %, stirred for 24 hours in a nitrogen atmosphere, then added xylene (45 g), and heated to 180° C. and stirred for 6 hours in a nitrogen atmosphere to remove water and cyclize to obtain a polyimide solution.

Synthesis Example 2

In a 500ml reaction flask, add diamine (3,3'-dihydroxybenzidine HAB 24.55g) and dianhydride (6FDA 50.45g) wherein the molar ratio of diamine and dianhydride is 1:1, solvent NMP (225g), Wherein the solid content is 20wt%~25wt%, stir under nitrogen environment for 24 hours, then add xylene (45g), and heat up to 180 ℃ and stir under nitrogen environment for 6 hours, carry out dewatering and cyclization to obtain polyimide solution.

Example 1

Add NMP (45g) and surfactant (5g) to a 500mL reaction flask, stir until uniformly dispersed, and then slowly pour the fluorine-containing polymer powder PFA (particle size <3μm, 50g) into the above solution in batches , and at the same time, stir until all is poured in, and continue to stir for 24 hours, that is, the fluorine dispersion without adding the polyimide solution is prepared.

Example 2

The fluorine dispersion liquid (30.4g) prepared in Example 1 was respectively added to the 100mL reaction flask, and stirred, and at the same time, Synthesis Example 1 (3.2g) was slowly added, and the stirring was continued for 24 hours, that is, the fluorine-containing dispersion liquid was prepared.

Example 3

The fluorine dispersion (28.8g) prepared in Example 1 was respectively added to the 100mL reaction flask, and stirred, and the polyimide solution (6.4g) prepared in Synthesis Example 1 was slowly added at the same time, and the stirring was continued for 24 hours, that is, the fluorine-containing solution was prepared. Dispersions.

Example 4

The fluorine dispersion (27.2g) prepared in Example 1 was respectively added to the 100mL reaction flask, stirred, and the polyimide solution (9.6g) prepared in Synthesis Example 1 was slowly added at the same time, and the stirring was continued for 24 hours, that is, the fluorine-containing solution was prepared. Dispersions.

Comparative Example 1

The difference from Example 1 is that the particle size of the fluorine-containing polymer powder PFA is 4 to 6 μm.

Comparative Example 2

The difference from Example 2 is that the fluorine dispersion prepared in Example 1 was replaced with the fluorine dispersion prepared in Comparative Example 1 (30.4 g).

Comparative Example 3

The difference from Example 2 is that baking is performed at 350°C.

Comparative Example 4

The difference from Example 2 is that the polyimide solution (3.2 g) synthesized in Synthesis Example 2 was used instead of the polyimide solution synthesized in Synthesis Example 1.

Comparative Example 5

The fluorine dispersion liquid (25.6g) prepared in Example 1 was respectively added to the 100mL reaction flask, and stirred, and at the same time, Synthesis Example 1 (12.8g) was slowly added, and the stirring was continued for 24 hours, that is, the fluorine-containing dispersion liquid was prepared.

Wherein, the formulas, preparation conditions and properties of Examples 1-4 and Comparative Examples 1-5 are shown in Table 1.

Table 1 Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 PFA powder particle size <3μm 100% 95% 90% 85% - 0 95% 95% 80% PFA powder particle size 4~6μm - - - - 100% 95% - - - Synthesis Example 1 - 5% 10% 15% - 5% 5% - 20% Synthesis Example 2 - - - - - - - 5% - Baking temperature(℃) 450 450 450 450 450 450 350 450 450 Film Formation (3-5μm) PASS PASS PASS PASS NG cannot form a film NG cannot form films NG phase separation NG phase separation NG phase separation Release force (kgf/cm) 0.017 0.043 0.073 0.098 - - - - -

Note: The ratio of PFA powder and polyimide in Table 1 is calculated based on the weight ratio of the solid content of PFA powder and polyimide in the fluorine-containing dispersion.

The particle size test of fluorine-containing polymer powder adopts ASTM D1210 standard.

The release force test adopts ASTM D3330 standard.

Release force - test method: test at room temperature, 4.5lb roller rolling, 180°, 300mm/min peel, the test standard is Nitto 31B.

The test results show that: from Example 1 and Comparative Example 1, it can be seen that the particle size of the fluorine-containing polymer powder (specifically PFA powder) in the fluorine dispersion in the present invention needs to be less than or equal to 3 μm, the reason is that when the PFA powder When the particle size is larger than 3, the fluorine-containing dispersion is prone to sedimentation and uneven thickness during coating, and when melted at high temperature, PFA powder particles with a particle size larger than 3 μm cannot be completely melted, resulting in inability to form a homogeneous film .

It can be seen from Examples 1-4 that the release force of the final formed fluorine-containing composite film can be controlled by adjusting the addition ratio of the polyimide solution and the PFA powder. It can be seen from the release force data in Table 1 that, The larger the added amount of the polyimide solution, the greater the release force of the final fluorine-containing composite membrane. The reason is that polyimide will generate polybenzoxazole under high temperature conditions, and the polarity of polybenzoxazole and PFA powder is different to a certain extent. By adjusting the ratio of the two, the final fluorine content can be well controlled. The release force of the composite film increases the selectivity of polyimide or other resin formulations in the process of polyimide film production, and both polybenzoxazole and PFA powder have good thermal properties (Td5%> 500 ℃ ), suitable for high temperature process.

It can be seen from Comparative Example 2 and Example 2 that the phenomenon of agglomeration and phase separation occurs in Comparative Example 2, because the particle size of the PFA powder is too large, the fluorine-containing dispersion is prone to sedimentation, and the thickness is uneven during coating.

It can be seen from Comparative Example 3 and Example 2 that since the polyimide solution of Synthesis Example 1 has hydroxyl groups (-OH), the hydroxyl groups are polar functional groups. The thermal recombination temperature of the amine solution, so the polyimide solution in Comparative Example 3 did not undergo thermal recombination. separation phenomenon.

As can be seen from Comparative Example 4 and Example 2, because the diamine monomer of Synthesis Example 2 is selected from HAB and does not contain fluorine elements, relative to Synthesis Example 1, the ratio of fluorine-containing elements is relatively low, thereby causing polyimide in Comparative Example 4. The compatibility with PFA powder decreased, resulting in the incompatibility between the two. Therefore, after coating film formation and high temperature sintering in Comparative Example 4, the phase separation phenomenon can be seen visually.

In Comparative Example 5, the phase separation phenomenon could be observed visually, and the film could not be homogeneously formed, and there was no reproducible data in the release force test. By comparing Comparative Example 5 with Examples 1-4, it can be seen that the reason for the above phenomenon is that due to the excessive amount of polyimide added, the addition of polybenzoxazole formed after coating film formation and high temperature sintering. The amount of PFA powder exceeds 15%, and the polarity of PFA powder is lower than that of polybenzoxazole. In this way, due to the large difference in polarity between the two, the phase separation is caused, and the homogeneous film cannot be formed, and the release force test has no reproducibility (by Release force test can be verified). In addition, the addition amount of polybenzoxazole is more than 15% (solid weight ratio), which will cause polybenzoxazole to agglomerate, which cannot be uniformly dispersed in the melt after the PFA powder is melted, thereby hindering the high-temperature melting of PFA and forming a film, which cannot be formed into a film. The continuous phase causes phase separation and voids.

To sum up, the beneficial effects of the present invention are: due to the existence of polybenzoxazole in the fluorine-containing composite film, the high temperature resistance is maintained, so that the fluorine-containing composite film still has the release force under high temperature conditions, which is suitable for high temperature process or Coating and film-forming process containing high boiling point solvent; by adjusting the ratio of fluorine-containing polymer powder and polybenzoxazole, the release force of the fluorine-containing composite film can be adjusted, which is suitable for different requirements for release force. Various polymer solutions are used to form films, which improves the formulation selectivity of polymer solutions; fluorine-containing composite films can realize double-sided release, which is suitable for traditional batch high-temperature curing in rolls, avoiding problems such as interlayer sticking during roll curing. At the same time, the double release surface can form a film at the same time, which improves the production efficiency; because the thickness of the polyimide film with the fluorine-containing composite film in the middle layer is thick and has sufficient stiffness and toughness, the fluorine-containing composite film can be used as the film. The carrier is directly coated and film-forming, and can be applied to the suspended online high-temperature curing process to improve production efficiency and reduce curling. The stretching process reduces the process threshold; there is no oxygen content limit in the film-forming process, and the fluorine-containing composite film can be recycled multiple times, saving costs and conforming to the trend of environmental protection.

The descriptions of the above embodiments and comparative examples are only used to help understand the method of the present invention and its core idea; in addition, for those of ordinary skill in the art, various other corresponding changes and modifications can be made according to the technical idea of the present invention , and all these changes and deformations should belong to the protection scope of the claims of the present invention.

100: Fluorine-containing composite membrane 1: Substrate 2: Fluorine-containing film 200: Polyamide film 300: Polyimide film

FIG. 1 is a flow chart of the preparation of the fluorine-containing composite membrane provided by an embodiment of the present invention.

FIG. 2 is a flow chart of the preparation of the thin film provided by an embodiment of the present invention.

FIG. 3 is a flow chart of the preparation of the thin film provided by another embodiment of the present invention.

100: Fluorine-containing composite membrane

1: Substrate

2: Fluorine-containing film

Claims (14)

A fluorine-containing dispersion liquid, wherein the solid content of the fluorine-containing dispersion liquid includes fluorine-containing polymer powder and polyimide, the particle size of the fluorine-containing polymer powder is less than or equal to 3 μm, and the fluorine-containing polymer powder The weight percent of the polymer powder in the solid content of the fluorine-containing dispersion is greater than or equal to 85%, and the weight percent of the polyimide in the solid content of the fluorine-containing dispersion is less than or equal to 15%. The fluorine-containing dispersion liquid according to claim 1, wherein the solid content of the fluorine-containing dispersion liquid is 40wt% to 50wt%. The fluorine-containing dispersion according to claim 1, wherein the fluorine-containing polymer powder comprises polytetrafluoroethylene, perfluoroalkoxy, polyperfluoroethylene propylene, chlorotrifluoroethylene, ethylene-chlorotrifluoroethylene One or more of ethylene and polyperfluorovinylidene. A kind of preparation method of fluorine-containing dispersion liquid, wherein, comprises the following steps: providing a first mixed solution, the first mixed solution comprising fluorine-containing polymer powder, and the average particle size of the fluorine-containing polymer powder is less than or equal to 3 μm; and adding a polyimide solution to the first mixed solution, and mixing to obtain the fluorine-containing dispersion, The polyimide solution includes polyimide, the fluorine-containing polymer powder and the polyimide constitute the solid content of the fluorine-containing dispersion, and the fluorine-containing polymer powder is in the The weight percentage in the solid content of the fluorine-containing dispersion is greater than or equal to 85%, and the weight percentage of the polyimide in the solid content of the fluorine-containing dispersion is less than or equal to 15%. The method for preparing a fluorine-containing dispersion according to claim 4, wherein the solid content of the fluorine-containing dispersion is 40 wt % to 50 wt %. The method for preparing a fluorine-containing dispersion according to claim 4, wherein the fluorine-containing polymer powder comprises polytetrafluoroethylene, perfluoroalkoxy, polyperfluoroethylene propylene, chlorotrifluoroethylene, ethylene- One or more of chlorotrifluoroethylene and polyperfluorovinylidene. A fluorine-containing composite film, comprising a base material and a fluorine-containing film disposed on at least one surface of the base material, the fluorine-containing film being heated by the fluorine-containing dispersion liquid according to any one of claims 1 to 3 made later. The fluorine-containing composite film according to claim 7, wherein the base material is a polyimide film, and the thickness of the base material is 125 μm˜225 μm. The fluorine-containing composite film according to claim 7, wherein the thickness of the fluorine-containing film is 3 μm˜6 μm. The fluorine-containing composite film according to claim 7, wherein the fluorine-containing composite film comprises fluorine-containing polymer powder and polybenzoxazole, and the fluorine-containing polymer powder is contained in the fluorine-containing composite film. The weight percentage is greater than or equal to 85%, and the weight percentage of the polybenzoxazole in the fluorine-containing composite film is less than or equal to 15%. A preparation method of a fluorine-containing composite membrane, comprising the following steps: provide a substrate; Coating the fluorine-containing dispersion according to any one of claims 1 to 3 on at least one surface of the substrate and drying to obtain an intermediate; and The intermediate body is sintered at 400° C. to 450° C. to obtain the fluorine-containing composite film. A preparation method of a polymer film, wherein, comprising the following steps: Provide a polymer solution and the fluorine-containing composite membrane as claimed in any one of claims 7 to 10; coating the polymer solution on the surface of the fluorine-containing film away from the substrate and baking to form an intermediate film layer; and The intermediate film layer is aged to form the polymer film. The method for preparing a polymer film according to claim 12, wherein the curing comprises the following steps: winding the intermediate film layer and the fluorine-containing composite film so that the film layer faces outward to obtain a semi-finished film roll; heating and curing the semi-finished film roll in a nitrogen atmosphere to form the polymer film; and The polymer film and the fluorine-containing composite film are respectively wound up. The method for preparing a polymer film according to claim 12, wherein the curing comprises the following steps: The intermediate film layer and the fluorine-containing composite film are heated in a nitrogen atmosphere by a suspended RTR process for online curing to form the polymer film; and The polymer film and the fluorine-containing composite film are respectively wound up.

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