A method and apparatus for the production of a thermoplastic polyimide film clad steel sheet

Abstract

The present application relates to the field of polyimide film, provide a kind of thermoplastic polyimide film steel plate preparation method and device, including the following steps;Provide steel foil, and prepare polyamide acid solution;Coated with a layer of polyamide acid solution on the rough surface of steel foil;The steel foil coated with polyamide acid solution obtained is placed on the rack in the furnace body and baked, and the steel foil covered with polyamide acid film is obtained;The steel foil covered with polyamide acid film obtained is subjected to thermal imidization, and the polyimide film steel plate is obtained.By being provided with the rack of metal material in the furnace body, the rack divides the furnace body into two heating cavities, and the two heating cavities are communicated through gap, and the heating pipe in lower chamber is heated towards the polyamide acid film on one side of copper foil, and the other side of polyamide acid film is not placed heating pipe, so that the heat in lower heating cavity is conducted to upper chamber through gap, and the other side of polyamide acid film is heated, and the heating efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of polyimide films, and more particularly to a method and apparatus for preparing thermoplastic polyimide film-coated steel sheets. Background Technology

[0002] Polyimide is a class of polymers containing an imide ring in its main chain, with polymers containing phthalimide structures being the most important. As a special engineering material, polyimide has been widely used in aerospace, microelectronics, nanotechnology, liquid crystals, separation membranes, lasers, and other fields.

[0003] Currently, the preparation methods for materials such as polyimide films and polyimide copper-clad laminates involve casting (or coating) a polyamic acid solution onto a substrate such as copper foil or stainless steel plate, followed by heat treatment to evaporate the solution and high-temperature imidization. Traditional heat treatment furnaces have only one heating mode and use casting film-forming technology, employing heat treatment to evaporate organic solvents. When the polyimide film is thinner than 30 micrometers, the solvent volume is small, the solvent evaporation time is fast, and the polyimide film is heated and dried evenly on both sides at a rapid drying speed. Therefore, bubbles and curling are rare in the polyimide film. However, when the thickness of the polyimide film is greater than 30 micrometers, polyimide copper-clad laminates are prone to blistering, curling, interlayer peeling, or interlayer turbidity. Based on this, this application is proposed. Summary of the Invention

[0004] One objective of this invention is to provide a method and apparatus for preparing thermoplastic polyimide film-coated steel sheets, in order to solve the technical problem that in the prior art, when the polyimide film is thick, it is easy for bubbles and curling to occur when the polyimide film is uniformly heated in a heating furnace using casting film forming technology.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: a method for preparing thermoplastic polyimide film-coated steel sheet, comprising the following steps;

[0006] S1. Provide steel foil and prepare a polyamic acid solution;

[0007] S2. Coat the rough surface of the steel foil with a layer of the polyamic acid solution obtained in step S1;

[0008] S3. Place the steel foil coated with polyamic acid solution obtained in step S2 on the material rack inside the furnace and bake it to obtain a steel foil covered with a polyamic acid film.

[0009] S4. The steel foil covered with polyamic acid film obtained in step S3 is thermally imidized to obtain polyimide film-coated steel plate;

[0010] S5. Hot-pressing the polyimide film obtained in step S3 with the steel foil using a hot-pressing method to obtain a copper-clad plate.

[0011] Preferably, the thickness of the steel foil is 10-60 microns.

[0012] Preferably, in step S3, the baking is performed using a gradient temperature rise, specifically, 70-80℃ for 1 hour or more, 90-100℃ for 1 hour or more, 110-120℃ for 1 hour or more, and then 160-200℃ for 1 hour or more.

[0013] Preferably, in step S4, the thermal imidization is performed at a temperature of 300-320℃ for 0.5 hours or more.

[0014] Preferably, in step S4, the thickness of the polyimide film is 1-5 microns.

[0015] A device for preparing a thermoplastic polyimide film copper-clad plate, comprising a furnace body, wherein the furnace body is internally provided with a rack parallel to the bottom of the furnace body, the rack is used for placing a steel foil coated with a polyamide acid solution, the rack divides the furnace body into two heating cavities in the upper and lower sides, the two heating cavities in the upper and lower sides are communicated through a gap, the heating cavity in the lower side is provided with a heating element, the heating element is used for heat-treating the steel foil coated with the polyamide acid solution, the furnace body is provided with a pneumatic cylinder, a hot-pressing head is arranged on the output end of the pneumatic cylinder, the hot-pressing head is located directly above the rack, the sidewall of the furnace body is provided with a suction assembly, the suction assembly is communicated with the heating cavities, and a wind pipe is communicated between the suction assembly and the heating cavities, and the wind pipe is internally provided with a filter assembly.

[0016] Preferably, the heating element is a heating pipe.

[0017] Preferably, the rack is a metal plate.

[0018] Preferably, the furnace body is internally provided with a control system, and the control system is used for supplying power to the furnace body and raising the temperature in the heating cavities.

[0019] Preferably, the inner wall of the furnace body is provided with an inner heat insulation layer.

[0020] The one or more technical solutions described above in the embodiments of the present application have at least the following technical effects or advantages:

[0021] By means of the above technical scheme, the metal material rack is arranged in the furnace body, so that the furnace body is divided into two heating cavities by the rack, the two heating cavities are communicated through the gap, the heating pipe in the lower cavity is arranged to heat the polyamide acid film on the one side of the copper foil, and the other side of the polyamide acid film is not provided with the heating pipe, so that the heat in the lower heating cavity is conducted to the upper cavity through the gap to heat the other side of the polyamide acid film, the heating efficiency is improved, and the temperature difference exists between the two sides of the polyamide acid film, that is, the temperature of the upper side of the polyamide acid film is lower than that of the lower side of the heating cavity, so that the temperature of the upper side of the polyamide acid film is lower than that of the side directly in contact with the steel foil, so that the temperatures of the two sides of the polyamide acid film are different, and the polyamide acid film has a certain temperature gradient, so that the organic solvent in the deep layer of the polyamide acid film can be volatilized, so that the organic solvent can be volatilized as much as possible, and the deformation and curling of the steel foil are avoided; when the copper-clad plate is manufactured by moving the hot head downward to heat and press the copper foil and the polyimide film, water mist is generated in the hot pressing process, the suction assembly can suck the water mist, the water mist is dried through the air pipe and the filter cotton, and then the dry airflow flows into the heating cavity again, so that the heating efficiency is improved and the heating time is shortened. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort.

[0023] Fig. 1 The operation step flow chart provided for the embodiments of the present application;

[0024] Fig. 2 The structural schematic diagram provided for the embodiments of the present application;

[0025] In the drawings, various reference signs represent:

[0026] 1, furnace body; 2, rack; 3, heating cavity; 31, heating element; 4, air cylinder; 5, hot head; 6, air pipe; 7, suction assembly; 8, filter assembly. DETAILED DESCRIPTION

[0027] The embodiments of the present application will be described in detail below, and examples of the embodiments are shown in the drawings, wherein the same or similar reference signs represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0028] In the description of the application, it is to be understood by the terms "length", "width", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, only for the convenience of describing the application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the application.

[0029] In addition, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0030] In the present application, unless otherwise specifically defined and limited, the terms "mounting", "connection", "connection", "fixing" and the like should be broadly understood, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0031] Please refer to Figs. 1-2 The embodiment of the present application provides a preparation method of a thermoplastic polyimide film covered steel plate, comprising the following steps:

[0032] S1. Provide a steel foil with a thickness of 10-60 microns, and prepare a polyamide acid solution, the polyamide acid solution is prepared by dissolving tetracarboxylic acid compounds and diamine compounds in DMAC or NMP solvent, the equivalent ratio of acid to amine is in the range of 0.9-1.0, and the polyamide acid solution is obtained by polymerization reaction at 4-35℃, wherein DMAC is N,N'-dimethylacetamide, and NMP is N-methyl pyrrolidone;

[0033] S2. A layer of polyamide acid solution obtained in step S1 is coated on the rough surface of the steel foil, and the coating speed is 6 m / min;

[0034] S3. The steel foil coated with polyamic acid solution obtained in step S2 is placed on the rack 2 inside the furnace body 1 at 80-200°C for baking. The baking inside the furnace body 1 adopts a gradient temperature increase, specifically 70-80°C for more than 1 hour, 90-100°C for more than 1 hour, 110-120°C for more than 1 hour, and then 160-200°C for more than 1 hour. This can remove DMAC or NMP organic solvents and dry the composition to obtain a steel foil covered with a polyamic acid film.

[0035] S4. The steel foil covered with polyamic acid film obtained in step S3 is subjected to thermal imidization. The polyamic acid film coated on the steel foil is thermal imidized in a furnace 1 with high temperature and nitrogen gas. Specifically, the thermal imidization is carried out at a temperature of 300-320°C for more than 0.5 hours to obtain a polyimide film-coated steel plate. The thickness of the polyimide film is 1-70 micrometers.

[0036] S5. The polyimide film obtained in step S3 is hot-pressed with steel foil to obtain copper-clad laminate.

[0037] In step S2, the coating can be done using coating equipment commonly used in the prior art;

[0038] In some embodiments, in step S3, as drying proceeds, during the coating process, DMAC or NMP organic solvents and the drying composition are removed, thereby avoiding large-volume shrinkage during subsequent thermal imidization, which would cause steel foil deformation. By using gradient heating, the remaining organic solvents are gradually dried in the furnace 1, so that the coated steel sheet can adhere as tightly as possible to the steel foil, effectively preventing the steel foil from curling.

[0039] A device for preparing thermoplastic polyimide film-coated steel sheets includes a furnace body 1. Inside the furnace body 1, there is a material rack 2 parallel to the bottom of the furnace body 1. The material rack 2 is used to place steel foil coated with polyamic acid solution. The material rack 2 divides the interior of the furnace body 1 into upper and lower heating chambers 3. The upper and lower heating chambers 3 are connected by a gap. The lower heating chamber 3 is equipped with a heating element 31. The heating element 31 is used to heat treat the steel foil coated with polyamic acid solution. A cylinder 4 is provided on the furnace body 1. A hot pressure head 5 is set on the output end of the cylinder 4. The pressure head is located directly above the material rack 2. A suction assembly 7 is provided on the side wall of the furnace body 1. The suction assembly 7 is connected to the heating chamber 3. A duct 6 is connected between the suction assembly 7 and the heating chamber 3. A filter assembly 8 is provided inside the duct 6.

[0040] The furnace body 1 is equipped with a control system, which is used to supply power to the furnace body 1 and raise and lower the temperature inside the heating chamber 3.

[0041] The above technical scheme is adopted, the steel foil coated with the polyamide acid solution is placed on the rack 2 for heating, and when heat treatment is performed, the heating pipe of the lower chamber of the heating cavity 3 in the furnace body 1 works, the heating pipe heats the polyamide acid film on the side in contact with the steel foil, the heat of the lower chamber is gradually conducted to the upper chamber through the gap channel because the upper and lower heating cavities 3 are only connected with each other through the gap, the temperature of the heating pipe of the upper heating cavity 3 is lower than that of the heating pipe in the lower heating cavity 3, the upper and lower sides of the steel foil and the polyamide acid film thereon have different heating, that is, the temperature of the upper side of the polyamide acid film is lower, the temperature of the upper side of the polyamide acid film is lower than that of the side directly in contact with the steel foil, the temperatures of the two sides of the polyamide acid film are different, the polyamide acid film has a certain temperature gradient inside, this is beneficial to the volatilization of the organic solvent in the deep layer of the polyamide acid film, so that the organic solvent can be volatilized as much as possible, and the deformation of the steel foil is avoided, and the speed of heat treatment of the polyamide acid film is improved by the way of simultaneous heating of the two sides; the steel foil of the polyamide acid film is heat imidized by the nitrogen gas charging system, specifically, the nitrogen gas charging system is a prior art, and a polyimide film is obtained; when the prepared polyimide film is applied to the copper-clad plate, the air cylinder 4 and the pressure head can be started to drive the pressure head to press downward, so that the pressure head directly presses the copper foil and the polyimide film into a two-layer flexible copper-clad plate; it should be noted that the hot pressing temperature of the hot pressing method is 330-360 DEG C, the pressure is 0.5 Mpa, and the hot pressing time is 30-60 s; and in the process of hot pressing, water mist is formed and gathered in the closed space, therefore, the suction assembly 7 is controlled to work, the suction assembly 7 can be a gas pump, etc., at this time, the suction assembly 7 sucks the water mist inside to flow towards the direction of the air pipe 6, and then is dried by the filtering assembly 8, specifically, the filtering assembly 8 can be filter cotton, water-absorbing sponge, etc., so that the mist forms dry air flow, and the dry hot air flow flows in the heating cavity 3 again through the outlet end of the air pipe 6, so that the hot pressing efficiency can be improved, and heat loss can be avoided as much as possible.

[0042] In some embodiments, the rack 2 is a metal plate, and the metal plate has good heat conduction effect, so that the heat of the heating pipe can be conducted to the polyamide acid film from the steel foil.

[0043] In some embodiments, the front side of the furnace body 1 can be provided with an observation assembly, specifically, the observation assembly can be an observation window, which can facilitate the observation of the progress of the steel plate by the worker.

[0044] In some embodiments, the inner wall of the furnace body 1 is provided with an inner heat insulation layer.

[0045] The above merely preferred embodiments of the present application are not used to limit the present application, any modification, equivalent replacement and improvement etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a thermoplastic polyimide film-coated steel sheet, characterized in that, The steps are as follows; S1. Provide steel foil and prepare a polyamic acid solution; S2. Coat the rough surface of the steel foil with a layer of the polyamic acid solution obtained in step S1; S3. Place the steel foil coated with polyamic acid solution obtained in step S2 on the rack (2) inside the furnace body (1) and bake it to obtain a steel foil covered with polyamic acid film; S4. The steel foil covered with polyamic acid film obtained in step S3 is thermally imidized to obtain a polyimide film; S5. The polyimide film obtained in step S3 is hot-pressed with steel foil to obtain copper-clad laminate; In step S3, the baking process employs a gradient temperature increase, specifically maintaining the temperature at 70-80℃ for more than 1 hour, at 90-100℃ for more than 1 hour, at 110-120℃ for more than 1 hour, and then at 160-200℃ for more than 1 hour. The specific steps of step S3 include: heating the polyamic acid film on the side in contact with the steel foil by the heating element (31) in the lower chamber of the heating chamber (3) inside the furnace body (1), and the heat from the lower chamber is gradually conducted to the upper chamber through the gap channel, so that the temperature of the upper and lower sides of the polyamic acid film is inconsistent, and the temperature of the upper chamber is lower than that of the lower chamber; wherein the upper chamber and the lower chamber are connected by the gap. The specific steps of step S5 include: using a cylinder (4) to drive the hot pressing head (5) downwards, so that the hot pressing head (5) directly presses the copper foil and the polyimide film into a two-layer flexible copper-clad board; the hot pressing temperature of the hot pressing method is 330-360℃, the pressure is 0.5Mpa, and the hot pressing time is 30-60s; during the hot pressing process, the suction component (7) is controlled to work, the suction component (7) sucks the water mist inside, so that the water mist flows towards the direction of the air duct (6), and then passes through the filter component (8) for drying, and the dried hot airflow flows again through the outlet end of the air duct (6) into the heating chamber (3).

2. The method for preparing a thermoplastic polyimide film-coated steel sheet according to claim 1, characterized in that: The thickness of the steel foil is 10-60 micrometers.

3. The method for preparing a thermoplastic polyimide film-coated steel sheet according to claim 1, characterized in that: In step S4, the thermal imidization specifically involves maintaining the temperature at 300-320°C for more than 0.5 hours.

4. The method for preparing a thermoplastic polyimide film-coated steel sheet according to claim 1, characterized in that, In step S4, the thickness of the polyimide film is 1-70 micrometers.

5. An apparatus for preparing thermoplastic polyimide film-coated steel sheets, characterized in that: The furnace includes a furnace body (1), inside which is a material rack (2) parallel to the bottom of the furnace body (1). The material rack (2) is used to place steel foil coated with polyamic acid solution. The material rack (2) divides the interior of the furnace body (1) into upper and lower heating chambers (3). The upper and lower heating chambers (3) are connected by a gap so that the upper and lower sides of the polyamic acid film have different temperatures, so that the temperature of the upper heating chamber (3) is lower than the temperature of the lower heating chamber (3). The lower heating chamber (3) is equipped with a heating element (31). The heating element (31) is used to heat treat the steel foil coated with polyamic acid solution. The furnace body (1) is provided with a cylinder (4) and a hot pressure head (5) is set on the output end of the cylinder (4). The hot pressure head (5) is located directly above the material rack (2). The side wall of the furnace body (1) is provided with a suction assembly (7). The suction assembly (7) is connected to the heating chamber (3). A duct (6) is connected between the suction assembly (7) and the heating chamber (3). A filter assembly (8) is provided in the duct (6).

6. The apparatus for preparing thermoplastic polyimide film-coated steel sheets according to claim 5, characterized in that: The heating element (31) is a heating tube.

7. The apparatus for preparing thermoplastic polyimide film-coated steel sheets according to claim 5, characterized in that: The rack (2) is a metal plate.

8. The apparatus for preparing thermoplastic polyimide film-coated steel sheets according to claim 5, characterized in that: The furnace body (1) is equipped with a control system, which is used to supply power to the furnace body (1) and raise and lower the temperature inside the heating chamber (3).

9. The apparatus for preparing thermoplastic polyimide film-coated steel sheets according to claim 5, characterized in that: The inner wall of the furnace body (1) is provided with an inner heat insulation layer.

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