JPS6225099B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to polyester laminated films.
More specifically, the present invention relates to a polyester laminated film that has excellent mechanical properties, electrical properties, heat resistance, chemical resistance, dimensional stability, etc., and is laminated with a conductive metal. Conventionally, laminated films in which a conductive metal layer is laminated on an electrically insulating film have been used for applications such as flexible printed circuits and tape carriers, and as electronic devices become smaller, lighter, and more precise. As a result, its importance is increasing. At present, polyester films, polyimide films, glass-epoxy films, etc. are mainly used as electrically insulating films. Polyester films, especially polyethylene terephthalate films, have excellent mechanical and electrical properties. However, it cannot be said that the heat resistance is sufficient; for example, polyethylene terephthalate film has a large shrinkage rate even at temperatures below the melting point, such as 230°C, and its range of use is severely limited.
Also, its chemical resistance and dimensional stability are inferior to, for example, thermosetting resins. On the other hand, polyimide film has excellent mechanical properties,
Although it has heat resistance, it has the disadvantage that it has a high equilibrium moisture content, does not have good dimensional stability and electrical properties, and is very expensive because it must be molded from a solution. Furthermore, glass epoxy film is a thermosetting resin and has the drawbacks of low elongation and lack of flexibility. The present inventors have simultaneously satisfied both properties, as the substrate film of the laminated film, which has the melt moldability and excellent electrical properties of saturated linear polyester, and also has heat resistance comparable to that of a curable resin. As a result of intensive research to solve the extremely difficult technical problem, a stretched film made from wholly aromatic polyester with a specific composition was developed.
The present invention was achieved based on the discovery that it has extremely good heat resistance, excellent dimensional stability and mechanical properties, and can be easily manufactured using conventional film forming and stretching methods. That is, the present invention provides a laminated film in which a conductive metal layer is laminated on at least one side of a polyester film, wherein the polyester film is a melt-formable wholly aromatic polyester whose main components are isophthalic acid residues and hydroquinone residues. film with an elongation of 10% at room temperature.
The shrinkage rate at 260℃ is 1% or less, and the average linear expansion coefficient from 260℃ to room temperature is 8×10 ^-5 mm/mm/
The present invention relates to a polyester laminated film characterized in that it is a stretched film having properties of 0.degree. As the conductive metal layer in the present invention, copper, aluminum, etc. are used, and copper foil is particularly preferably used. Further, although there are two types of copper foil, electrolytic copper foil and rolled copper foil, electrolytic copper foil is generally used. Particularly when flexibility is required, rolled copper foil is preferably used. These copper foils are bonded to polyester stretched films using an adhesive, as will be described in detail later. In this case, it is preferable to use a surface-oxidized copper foil with good adhesive properties. As a method for forming a conductive metal layer, especially a copper layer, on a wholly aromatic polyester stretched film, a method using a combination of electroless copper plating and electrolytic copper plating is also preferably used. In the present invention, a melt-moldable fully aromatic polyester containing isophthalic acid residues and hydroquinone residues as its main components has a melting point of 400°C or less, and contains isophthalic acid residues and hydroquinone residues constituting the polyester. A wholly aromatic polyester in which the sum of isophthalic acid residues and hydroquinone residues accounts for 80 mol% or more of all component residues constituting the polyester, preferably 95 to 82 mol% of all component residues constituting the polyester. A certain wholly aromatic polyester, particularly preferably a wholly aromatic polyester in which the sum of isophthalic acid residues and hydroquinone residues is 95 to 85 mol % of all component residues constituting the polyester. Components that provide component residues other than isophthalic acid residues and hydroquinone residues in the fully aromatic polyester in the present invention include:
For example, terephthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid,
Diphenyl ether-4,4'-dicarboxylic acid, P
- Other aromatic dicarboxylic acids or aromatic oxycarboxylic acids such as oxybenzoic acid, m-oxybenzoic acid, 6-oxy-2-naphthoic acid; resorcinol, 2,2-bis(4-oxyphenyl)propane, 1. 1-bis(4-oxyphenyl)cyclohexane, phenolphthalein, 4,4'-dioxydiphenyl ether, 4,4'-dioxydiphenyl, 2,6-dioxynaphthalene, 1,5-
Examples include aromatic dioxy compounds such as dioxynaphthalene and 1,4-dioxynaphthalene. Among these, resorcinol, 2.2-
Compounds such as bis(4-oxyphenyl)propane are preferably used because the resulting copolyester has excellent stretchability. The wholly aromatic polyester in the present invention is preferably produced by a combination of a melt polymerization method and a solid phase polymerization method. It is preferable to do so. Preferred specific examples of the method for producing the wholly aromatic polyester used in the present invention include (1) an aryl ester of isophthalic acid, and optionally an aryl ester of another aromatic dicarboxylic acid or aromatic oxycarboxylic acid; Hydroquinone, and optionally further aromatic dioxy compounds, are thermally polymerized; (2) isophthalic acid, optionally further aromatic dicarboxylic acids or aromatic oxycarboxylic acids, and hydroquinone, optionally Further, another aromatic dioxy compound and a diaryl carbonate may be reacted by heating, and the carboxylic acid may be polymerized while being subjected to an esterification reaction with the diaryl carbonate. Among the methods for producing wholly aromatic polyesters, the method (1) above is particularly preferred since it has a good possibility of introducing carbonate bonds into the polyester. A catalyst is preferably used in the above-mentioned method for producing wholly aromatic polyester. Examples of the catalyst include calcium, magnesium, strontium, barium, lanthanum, cerium, titanium, manganese, cobalt, zinc, germanium,
Among compounds containing metals such as tin, antimony, and bismuth, those conventionally known as this type of transesterification catalyst are preferably used.
More specific compounds include magnesium acetate, calcium benzoate, strontium acetate,
Lanthanum carbonate, cerium oxide, titanium tetrabutoxide, manganese acetate, cobalt acetate,
Examples include zinc acetate, germanium oxide, stannous acetate, antimony trioxide, and bismuth trioxide. The amount of these catalysts used is preferably 0.001 to 0.2 gram atoms, calculated as metal atoms contained in the catalyst, per 100 moles of the total acid components constituting the polyester. These catalysts are usually added to the reaction system from the beginning of the reaction. The wholly aromatic polyester used in the present invention is usually polymerized according to the above-mentioned polymerization method.
Preferably it is carried out at 270-340°C. Melt polymerization is carried out at a relatively low temperature (e.g. 250-300°C) under normal pressure at the initial stage of polymerization.
Preferably, the reaction is carried out at During this time, compounds produced by the reaction, such as phenol, are distilled out of the reaction system. The reaction rate calculated from the distilled amount of by-products is 50
%, the pressure of the reaction system is gradually reduced and the temperature is raised at the same time to 350℃ or less, preferably
It is preferable to further proceed and complete the melt polymerization at a temperature of 340° C. or lower. The prepolymer obtained in this way usually has a reduced viscosity (ηsp/c) of
It is a relatively low polymer with a molecular weight of 0.6 or less. If an attempt is made to obtain a high polymer using only the melt polymerization method and the reaction is carried out at high temperature for a long period of time, branching or crosslinking reactions occur as side reactions, which makes it difficult to obtain the polyester film that is the object of the present invention even after stretching. The prepolymer obtained by the above melt polymerization is preferably subjected to solid phase polymerization to form a high polymer suitable for film formation. In solid phase polymerization, a prepolymer obtained by melt polymerization is turned into powder or granules of a predetermined size, such as chips, pellets, powder, etc., and the granules are formed under conditions that do not fuse together and form blocks. It is preferable to do so. As the solid state polymerization progresses, the temperature at which the powder or particulate material is fused increases, so that the solid state polymerization temperature can be gradually increased. During this time, it is preferable to stir the granular material. The solid state polymerization temperature is
The temperature is selected from a temperature at which the polymerization reaction proceeds and does not block, but usually about 230-320°C, preferably about 230-320°C.
The temperature is 250-300℃. Further, the reaction atmosphere is preferably an atmosphere under an inert gas flow (for example, under a nitrogen gas flow) or under reduced pressure, and the latter is particularly preferred. The solid phase polymerization time depends on the degree of polymerization of the prepolymer, the desired degree of polymerization, the shape and size of the powder, the temperature,
Determined by the atmosphere etc. The reduced viscosity of the wholly aromatic polyester is preferably 0.6 or more, particularly preferably 0.7 or more and 1.5 or less. In the present invention, the stretched film is a film made of the above-mentioned wholly aromatic polyester, and has an elongation at room temperature of 10% or more, a shrinkage rate at 260°C of 1% or less, and an average linear expansion coefficient from 260°C to room temperature. It is a stretched film having a characteristic of 8×10 ^-5 mm/mm/°C or less. The elongation at room temperature is a value measured at a tensile rate of 100%, and this value is 10% or more, preferably 20% or more, and more preferably 30%.
It is particularly preferably 50% or more. If the elongation at room temperature is less than 10%, the desired performance in terms of flexibility cannot be achieved. Further, the shrinkage rate at 260°C is the shrinkage rate when the temperature is maintained at 260°C for 1 minute, and this value is 1% or less, preferably 0.5% or less. If it is more than 1%, when used as a laminated film at high temperatures, undesirable phenomena such as curling and distortion due to shrinkage of the film occur. Furthermore, the average coefficient of linear expansion from 260°C to room temperature is 8 x 10 ^-5 mm/mm/°C or less, preferably 6 x 10 ^-5 mm/mm/°C or less.
Average linear expansion coefficient from 260℃ to room temperature is 8×10 ^-5
If it is larger than mm/mm/°C, the laminated film will curl when subjected to temperature changes. The strength of the stretched film at room temperature is preferably 7 kg/mm ² or more, more preferably 8 kg/mm ²
Above, particularly preferably 10 Kg/mm ² or above. Such a stretched film can be obtained by the following method. The fully aromatic polyester is melted at a temperature above its melting point, preferably below 400°C, melt-extruded through a slit, biaxially stretched sequentially or simultaneously, then heat-set, and further heat-shrinked to determine the heat shrinkage rate. It can be made into a biaxially stretched film with small heat resistance and excellent heat resistance. The slit used here has a width of, for example, 0.1 mm to 5 mm.
The unstretched film extruded from the slit is then biaxially stretched by conventionally known means. At this time, the stretching temperature is preferably in the range of 180 to 280°C, more preferably 180 to 250°C, particularly preferably 190 to 250°C. The stretching ratio is preferably 1.5 times or more in the machine axis direction and the direction perpendicular to the machine axis direction, and 2.5 times or more in area magnification. More preferably, it is 1.5 times or more in both axial directions and 3.0 times or more in area magnification, particularly preferably 2.0 times or more in both axial directions and 4 times or more in area magnification. There is no particular restriction on the stretching speed for polyester film stretching, but it is usually 1 second.
It is carried out in the range of 0.05 to 0.5 times. After the polyester film is biaxially oriented under the above-mentioned conditions, it is heat-set for the purpose of further improving dimensional stability. This heat fixing is preferably carried out at a temperature range of 250°C to 20°C lower than the melting point of the wholly aromatic polyester, more preferably 260°C to 30°C lower than the melting point of the wholly aromatic polyester. . The heat setting time is selected to be at least 2 seconds, preferably between 10 seconds and 3 minutes. This heat setting is carried out with the film under tension, and it is generally preferable to keep the stretched film at a constant length, but for example, it is limited to within 20% in the mechanical axis direction of the film and/or in a direction perpendicular to the mechanical axis direction of the film. Heat setting can also be performed while giving shrinkage. In the present invention, the heat-set biaxially stretched film is preferably continuously heated at 200°C.
Shrinkage treatment is carried out at a temperature above and lower than the heat setting temperature and under such conditions as to give a shrinkage of 1% or more. This heat shrinking treatment temperature is preferably 220°C or higher and lower than the heat setting temperature, more preferably
The temperature is 250°C or higher and lower than the heat setting temperature. Further, the shrinkage ratio at this time is 1% or more, preferably 1% to 30%, more preferably 1% to 20%, and the heat shrinkage time can be selected between 2 seconds and 2 minutes. In this case, the contraction is performed in at least one of the mechanical axis direction and the direction perpendicular to the mechanical axis, particularly preferably in both directions. When successive biaxial stretching is adopted as the stretching method and shrinkage treatment is performed only in one direction, it is preferable that the shrinkage be performed in the same direction as the second-stage stretching direction. In this way, a stretched film having the above-mentioned properties can be obtained. Further, the stretched film may contain a reinforcing agent such as glass fiber, mica, or talc. The polyester laminated film of the present invention can be obtained by laminating a conductive metal layer on at least one side of the above-mentioned stretched film. Various methods can be used for lamination, including (1) adhesive lamination of conductive metal foil on a stretched film; (2) depositing a conductive metal layer on the stretched film by electroless plating. It can be broadly divided into methods. The lamination method by adhesion is a generally widely used method, and is also used in the production of the polyester laminated film of the present invention. The adhesive is preferably one that not only has good adhesion to the stretched film and conductive metal foil, but also has excellent electrical properties and heat resistance. In the polyester laminated film of the present invention, adhesives used as general polyester adhesives can be used as they are, but urethane-modified polyester adhesives, polyester-modified epoxy adhesives, etc. are preferably used, especially urethane-modified polyester adhesives. agents are preferably used. Adhesion is carried out by continuously applying a solution of the above adhesive onto the stretched film using a roll coater or the like, and after drying the solvent by heating, pressing it with a conductive metal foil using a heated roller. The polyester laminate film of the present invention can be industrially advantageously produced by the method described above. Further, in the polyester laminate film of the present invention, it is also possible to form a conductive metal layer by electroless plating. In this case, a copper layer is formed on the stretched film by activating the surface of the stretched film by a conventionally known method and then immersing it in an electroless plating solution, particularly an electroless copper plating solution. . The thickness of the copper layer is about 10μ
In the following cases, the purpose can be achieved by electroless plating alone, but if it is necessary to form an even thicker copper layer, it is possible to easily thicken the copper layer by using electroless plating and then electrolytic plating. You can get layers. Further, in order to improve adhesion to copper foil, it is preferable to perform soft etching such as amine treatment beforehand. Since the polyester laminated film of the present invention uses a stretched film made of wholly aromatic polyester as a substrate, it retains the excellent electrical properties of polyester film, and is also heat resistant enough to be used at high temperatures of 260 to 300°C. It has a sexual nature. In addition, it has appropriate flexibility, so it can be bent freely, and has low water absorption, low thermal contraction coefficient, and low coefficient of linear expansion, and excellent dimensional stability. The laminated film in the present invention can be used for flexible printed circuits, tape carriers, etc.
Effectively applied to materials that require heat resistance and flexibility. The present invention will be described in detail below with reference to Examples. In the examples, "parts" means "parts by weight." Example 1 190.80 parts of diphenyl isophthalate, 55.44 parts of hydroquinone, 28.73 parts of bisphenol A, and 0.070 parts of antimony trioxide were placed in a polymerization pot and heated to a temperature of 250 to 285°C in a nitrogen stream to produce the product as a result of the reaction. 73 parts of phenol (approximately 65% of theory) were distilled off. Next, the pressure of the reaction system was gradually reduced, and at the same time the reaction temperature was raised, and it took about 1 hour to reduce the pressure.
20mmHg, reaction temperature 330℃, and further under the same conditions.
Polymerization was continued for 30 minutes, followed by 15 minutes at 5 mmHg and 330°C. The reduced viscosity of the obtained polymer was 0.51. At this point, the melt polymerization was stopped, the polymer was pulverized, and further heated at 250°C under a reduced pressure of 0.2 mmHg for 2 hours.
Solid phase polymerization was carried out at 270°C under reduced pressure of 0.2 mmHg for 24 hours. The melting point of the obtained high polymerization degree polymer is 355
The melt viscosity at 380°C and a shear rate of 100sec ^-1 was 13,000 poise. This highly polymerized polymer is melted at 370°C and extruded through a T-die with a slit width of 1.5 mm, and the resulting raw fabric is stretched at 200°C twice in the direction perpendicular to the machine axis and then twice in the machine axis direction. Then, heat set at 285℃ for 10 seconds at a fixed length, and then heat set at 283℃ for 10 seconds in the machine axis direction.
% and 5% in the direction perpendicular to the machine axis. The elongation of the biaxially stretched film obtained here,
The shrinkage rate at 260°C and the average coefficient of linear expansion from 260°C to room temperature were measured. The results are shown in Table 1. Next, this stretched film was degreased with acetone, and an adhesive having the following composition of 7.5 parts of RV-300 (Toyobo), 1 part of Coronate L (Japan Polyurethane Industries), and 17.5 parts of methyl ethyl ketone was applied using a bar coater (No. 20).
This was dried in vacuum at 40°C for 1 hour to remove methyl ethyl ketone. The above adhesive was similarly applied to a 35μ thick electrolytic copper foil and dried. The stretched film and copper foil were thermocompressed between two rollers heated to 150°C, and further heat treated at 170°C for 10 minutes to harden the adhesive layer. Table 1 shows the heat resistance of the obtained laminated film and the peel strength of the copper foil. Example 2 The original fabric obtained in Example 1 was heated at 200°C by 2 times in the direction perpendicular to the machine axis direction, and then by 2 times in the machine axis direction.
Stretch it twice, heat set it at 270℃ for 10 seconds, and then
It was shrunk by 4% in the direction of the machine axis and by 2% in the direction perpendicular to the machine axis for 60 seconds at 265°C. The stretched film obtained here was laminated with copper foil in the same manner as in Example 1. The elongation at room temperature of the stretched film, the shrinkage rate at 260 ° C., the average linear expansion coefficient from 260 ° C. to room temperature, and the heat resistance of the laminated film,
Table 1 shows the peel strength of the copper foil. Example 3 The original fabric obtained in Example 1 was heated at 210°C by 2.5 times in the direction perpendicular to the machine axis direction, and then in the machine axis direction.
It was stretched 2.5 times, heat set at 270°C for 10 seconds at a constant length, and further shrunk by 6% in the machine axis direction and 2% in the direction perpendicular to the machine axis for 60 seconds at 265°C. This stretched film was laminated with copper foil in the same manner as in Example 1. Elongation of the stretched film at room temperature, 260
Table 1 shows the shrinkage rate at °C, the average coefficient of linear expansion from 260 °C to room temperature, the heat resistance of the laminated film, and the peel strength of the copper foil. Example 4 A highly polymerized polyester was obtained in the same manner as in Example 1 using 190.80 parts of diphenyl isophthalate, 48.56 parts of hydroquinone, 20.81 parts of resorcinol, and 0.070 parts of antimony trioxide. The melting point of this polyester is 325℃, 380℃, shear rate
The melt viscosity at 100 sec ^-1 was 11000 poise. This highly polymerized polyester was extruded and stretched in the same manner as in Example 1, heat-set at 265°C for 10 seconds at a constant length, and further stretched for 30 seconds in the machine axis direction at 263°C.
% and 4% in the direction perpendicular to the machine axis, respectively. The biaxially stretched film obtained here was used in Example 1.
I did the same thing and glued it with copper foil. Table 1 shows the elongation of the stretched film at room temperature, the shrinkage rate at 260°C, the average coefficient of linear expansion from 260°C to room temperature, the heat resistance of the laminated film, and the peel strength of the copper foil. Comparative Example 1 A laminated film was prepared in the same manner as in Example 1 except that polyethylene terephthalate film was used as the substrate film, and the heat resistance of the laminated film and the peel strength of the copper foil were measured. The result is the first
Shown in the table. 【table】

Claims (1)

[Claims] 1. A laminated film in which a conductive metal layer is laminated on at least one side of a polyester film, where the polyester film is a film made of a melt-formable wholly aromatic polyester whose main components are isophthalic acid residues and hydroquinone residues. Stretched film with properties such as elongation at room temperature of 10% or more, shrinkage rate at 260°C of 1% or less, and average linear expansion coefficient from 260°C to room temperature of 8 x 10 ^-5 mm/mm/°C or less. A polyester laminated film characterized by: