Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
  • B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/36—Layered products comprising a layer of synthetic resin comprising polyesters
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B37/00—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding
  • B32B37/06—Methods or apparatus for laminating, e.g. by curing or by ultrasonic bonding characterised by the heating method
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
  • B32B7/02—Physical, chemical or physicochemical properties
  • B32B7/027—Thermal properties
  • B32B7/028—Heat-shrinkability

Definitions

• the present invention relates to a liquid crystal polymer film laminate, a method for producing a liquid crystal polymer film laminate, a method for producing a liquid crystal polymer film, and a liquid crystal polymer film.
• liquid crystal polymer film As a polymer film used in electronic materials, a liquid crystal polymer film is known that has excellent heat resistance, low water absorption, and small dimensional change rate. Since liquid crystal polymer films also have excellent high-frequency characteristics and low dielectric properties, they are expected to be used in flexible printed wiring boards used in fifth-generation mobile communication systems. Films used in flexible printed wiring boards may be required to have solder heat resistance of 300°C or more. Liquid crystal polymers that meet such requirements have a melting point exceeding 300°C, so molding processing must be performed at high temperatures. However, liquid crystal polymers heated at high temperatures are prone to deterioration and are difficult to mold.
• Patent Document 1 heat treatment to improve the heat resistance of liquid crystal polymer films requires long-term heating at temperatures above the flow start temperature, which is near the melting point. For this reason, the technology described in Patent Document 1 has the problem that the film deforms during heat treatment of the liquid crystal polymer film, causing deterioration in its shape. As a result, a method has been proposed in which the liquid crystal polymer film is laminated with metal foil by thermocompression or the like, and then heat-treated (for example, Patent Document 2).
• Patent Document 3 a manufacturing method has been proposed that prevents the liquid crystal polymer film wound into a roll from fusing together.
• a laminate roll (a roll wound under a predetermined tension by a winding device or the like) in which a laminate formed by thermocompression bonding of a liquid crystal polymer film and a metal foil is wound is subjected to a batch-type heat treatment, and at least the winding start end of the laminate is heat-treated in a state in which it is not subjected to contact pressure from the outer laminate surface and the core surface.
• this method it is necessary to prepare a roll by winding the laminate film so that it does not come into contact, which not only reduces productivity but also deteriorates the shape of the film during heat treatment.
• Patent Document 1 JP-A-11-291329
• Patent Document 2 JP-A-2000-44797
• Patent Document 3 Japanese Patent No. 5090308
• Patent Document 4 Japanese Patent No. 3756836
• the object of the present invention is to provide a liquid crystal polymer film laminate that can suppress deformation due to heat treatment and produce a heat-treated liquid crystal polymer film with excellent heat resistance, and a method for manufacturing a liquid crystal polymer film laminate. It is also to provide a method for manufacturing a liquid crystal polymer film using the liquid crystal polymer film laminate, and a liquid crystal polymer film.
• a liquid crystal polymer film laminate comprising a liquid crystal polymer film layer and a pair of support film layers laminated on both sides of the liquid crystal polymer film layer, wherein the support film layer is made of a crystalline resin, and the liquid crystal polymer film laminate has a dimensional change rate of 0% to -2% when heated at a temperature in the range of Tm LCP -80°C to Tm LCP of the melting point of the liquid crystal polymer constituting the liquid crystal polymer film.
• the liquid crystal polymer film laminate of aspect 1 in which when the liquid crystal polymer film laminate is deformed at a bending angle of 120° relative to the surface of one of the support film layers and then deformed at a bending angle of 120° relative to the surface of the other support film layer, there is no peeling between the liquid crystal polymer film layer and the support film layer.
• a liquid crystal polymer film laminate according to aspect 1 or 2 in which the crystalline resin constituting the support film layer is an aromatic polyether ketone or polyester.
• a method for producing a liquid crystal polymer film laminate comprising: a laminate formation step of obtaining a laminate in which a pair of the support film layers are laminated on both sides of the liquid crystal polymer film layer; a stretching step of stretching the laminate in the longitudinal direction and/or the width direction; and a relaxation step of subjecting the laminate to a relaxation treatment under a condition of a temperature TR that satisfies the following formula (2): T R1 ⁇ T R ⁇ T R2 (2)
• T R1 represents a temperature that is the melting point Tm LCP of the liquid crystal polymer -50°C
• T R2 represents a temperature that is the melting point Tm LCP of the liquid crystal polymer +20°C.
• the laminate formation step includes laminating a pair of the support film layers on both sides of the liquid crystal polymer film layer by pressure lamination or heat lamination.
• a method for producing a liquid crystal polymer film laminate according to any one of aspects 5 to 7, which includes a surface treatment step of performing a surface treatment on both sides of the liquid crystal polymer film layer and on the surface of the support film layer that is to be bonded to the liquid crystal polymer film layer prior to the laminate formation step.
• a method for producing a liquid crystal polymer film comprising a heat treatment step of subjecting a liquid crystal polymer film laminate according to any one of aspects 1 to 4 to a heat treatment at a temperature T H that satisfies the following formula (3): T H1 ⁇ TH ⁇ TH2 (3)
• T H1 represents the melting point Tm LCP of the liquid crystal polymer ⁇ 80° C.
• T H2 represents the melting point Tm LCP of the liquid crystal polymer.
• aspect 12 of the present invention there is provided a method for producing a liquid crystal polymer film according to aspect 11, in which the heat treatment step is carried out while the liquid crystal polymer film laminate is wound into a roll or while the liquid crystal polymer film laminate is stacked.
• a method for producing a liquid crystal polymer film according to aspect 11 or 12 characterized in that in the heat treatment step, heat treatment is performed so that the melting point Tm H-LCP of the liquid crystal polymer film after the heat treatment is equal to or higher than the melting point Tm LCP of the liquid crystal polymer before the heat treatment.
• the liquid crystal polymer film laminate of the present invention makes it possible to produce a liquid crystal polymer film that is suppressed from being deformed by heat treatment and has excellent heat resistance.
• the liquid crystal polymer film laminate of the present invention is composed of a liquid crystal polymer film layer and a pair of support film layers laminated on both sides of the liquid crystal polymer film layer.
• the support film layer is made of a crystalline resin.
• the liquid crystal polymer film laminate of the present invention is heated at a temperature ranging from room temperature to the melting point Tm LCP -80°C of the liquid crystal polymer to Tm LCP , the dimensional change rate is 0% to -2%.
• the liquid crystal polymer film laminate of the present invention is used for producing a liquid crystal polymer film by subjecting it to a heat treatment and then peeling off the support film layer.
• the liquid crystal polymer film layer used in the present invention is made of a liquid crystal polymer.
• the liquid crystal polymer is not particularly limited, but a liquid crystal polyester exhibiting thermotropic liquid crystal properties is preferable.
• liquid crystal polyesters include aromatic polyesters synthesized from monomers such as aromatic diols, aromatic carboxylic acids, and hydroxycarboxylic acids, and exhibiting liquid crystal properties when melted. Specific examples include polycondensates of ethylene terephthalate and parahydroxybenzoic acid, polycondensates of phenol, phthalic acid, and parahydroxybenzoic acid, and polycondensates of hydroxynaphthoic acid and parahydroxybenzoic acid.
• an aromatic polyester-based liquid crystal polymer having 6-hydroxy-2-naphthoic acid and its derivatives as a basic structure and at least one selected from the group consisting of parahydroxybenzoic acid, terephthalic acid, isophthalic acid, 6-naphthalenedicarboxylic acid, 4,4'-biphenol, bisphenol A, hydroquinone, 4,4-dihydroxybiphenol, ethylene terephthalate, and derivatives thereof as a monomer component is preferable.
• the liquid crystal polymers may be used alone or in any combination and ratio of two or more.
• the content of the liquid crystal polymer is preferably 50 to 100% by mass, more preferably 60 to 100% by mass, and even more preferably 70 to 100% by mass, based on the total amount of the stretched liquid crystal polymer film.
• the liquid crystal polyester can be synthesized by any known method, and is not particularly limited. For example, melt polymerization, melt acidolysis, slurry polymerization, etc. can be used. When applying these polymerization methods, acylation or acetylation may be performed according to the usual method.
• the liquid crystal polymer may contain additives such as polymers such as fluororesins, polyolefins, polycycloolefins, polyetherimides, and silicone-modified polyetherimides, release improvers such as higher fatty acids having 10 to 25 carbon atoms, higher fatty acid esters, higher fatty acid amides, and higher fatty acid metal salts, chain extenders such as aliphatic carbodiimides, alicyclic carbodiimides, and aromatic carbodiimides, colorants such as dyes, pigments, and carbon black, organic fillers, inorganic fillers, hollow particles, antioxidants, heat stabilizers, light stabilizers, ultraviolet absorbers, flame retardants, lubricants, antistatic agents, surfactants, rust inhibitors, foaming agents, defoamers, and fluorescent agents, within the scope of the invention that does not excessively impair the effects of the present invention.
• additives such as polymers such as fluororesins, polyolefins, polycyclo
• polymers and additives can be included in the molten resin composition during the formation of the liquid crystal polymer film.
• each of these polymers and additives can be used alone or in combination of two or more.
• the content of the polymer or additive is not particularly limited, but from the viewpoint of moldability and thermal stability, it is preferably 0.01 to 50% by mass, more preferably 0.1 to 40% by mass, and even more preferably 0.5 to 30% by mass, relative to the total amount of the liquid crystal polymer film layer.
• the liquid crystal polymer film used as the liquid crystal polymer film layer can be manufactured by a known method.
• a liquid crystal polymer can be formed into a film by a melt extrusion film-forming method using a T-die (T-die melt extrusion).
• a liquid crystal polymer film can be obtained by melt-kneading the liquid crystal polymer in an extruder, extruding the molten resin through a T-die, and solidifying it on a metal roll.
• touch molding with a rubber roll or a metal roll can also be used.
• the temperature of the cylinder of the extruder is preferably 230 to 360°C, more preferably 280 to 350°C.
• the slit interval of the T-die can be appropriately set depending on the type and composition of the liquid crystal polymer used, the performance of the desired film, etc.
• the slit interval of the T-die is not particularly limited, but is preferably 0.1 to 1.5 mm, more preferably 0.3 to 1.0 mm.
• the thickness of the liquid crystal polymer film layer is not particularly limited, but from the viewpoint of ease of handling and productivity during T-die melt extrusion molding, it is preferably 10 to 500 ⁇ m, more preferably 20 to 300 ⁇ m, and even more preferably 30 to 250 ⁇ m.
• the melting point Tm LCP of the liquid crystal polymer constituting the liquid crystal polymer film layer is preferably 250 to 380° C., more preferably 280 to 350° C.
• the glass transition temperature Tg of the liquid crystal polymer constituting the liquid crystal polymer film layer is preferably 80 to 150° C., more preferably 90 to 150° C., and even more preferably 90 to 120° C.
• the support film layer is a polymer film laminated on the liquid crystal polymer film layer to prevent the film layer from breaking when the liquid crystal polymer film layer is stretched.
• the support film layer is made of a crystalline resin, and the crystalline resin is preferably, for example, an aromatic polyether ketone or a polyester.
• aromatic polyether ketones include polyether ketone (PEK), polyether ether ketone (PEEK), polyether ketone ketone (PEKK), and polyether ether ketone ketone (PEEKK).
• Specific examples of polyesters include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polybutylene terephthalate (PBT).
• polyether ether ketone PEEK
• PET polyethylene terephthalate
• PBT polybutylene terephthalate
• PEEK polyether ether ketone
• the thickness of the support film layer is preferably 5 to 300 ⁇ m, and more preferably 15 to 100 ⁇ m.
• the support film layer used in the present invention preferably has the following characteristics. That is, at any temperature in the range of temperature T S1 or more and temperature T S2 or less, the total value of the yield load of the pair of support film layers is preferably larger than the yield load of the liquid crystal polymer film layer.
• temperature T S1 is the glass transition temperature Tg of the liquid crystal polymer
• temperature T S2 is the lower of the melting point Tm LCP of the liquid crystal polymer and the melting point Tm S -20°C of the crystalline resin constituting the support film.
• the laminate of the support film layer and the liquid crystal polymer film layer can be stretched at a temperature of the melting point Tm LCP of the liquid crystal polymer or less at a stretch ratio of 2 or more without breaking the liquid crystal polymer film layer.
• liquid crystal polymer film manufacturing techniques typically stretch the liquid crystal polymer in a molten state at a temperature above the melting point of the liquid crystal polymer.
• the relationship between the yield load of the support film layer and the yield load of the liquid crystal polymer film layer satisfies the above condition, so that the laminate of the liquid crystal polymer film layer and the support film layer can be stretched at a temperature equal to or lower than the melting point Tm LCP of the liquid crystal polymer and at a stretching ratio of 2 times or more.
• the reason why the liquid crystal polymer film layer can be stretched at a temperature equal to or lower than the melting point Tm LCP by the yield load of the liquid crystal polymer film layer and the support film layer satisfying the above relationship is not clear, but the following is considered.
• the case where the temperature Ts 2 is the melting point Tm LCP of the liquid crystal polymer, that is, the melting point Tm LCP of the liquid crystal polymer is lower than the melting point Tm S -20°C of the polymer constituting the support film is considered.
• a temperature range for example, 150 to 280°C
• the elastic modulus of the liquid crystal polymer falls below 1000 MPa, and soft parts are generated in the liquid crystal polymer film layer.
• the total value of the yield load of the pair of support film layers exceeds the yield load of the liquid crystal polymer film layer.
• the stretching load applied when the laminate is stretched is supported by the support film layer. Therefore, even if the liquid crystal polymer film layer becomes thin by stretching and a portion where the load is reduced occurs, it is possible to suppress the concentration of tensile stress in the portion where the load is reduced.
• the stretching force is applied evenly to the liquid crystal polymer film layer through the interface with the liquid crystal polymer film layer as the support film layer is stretched. From the above, it is considered that the liquid crystal polymer film layer can be stretched without breaking.
• the temperature T S2 is the melting point Tm S -20°C of the crystalline resin constituting the support film, that is, when the melting point Tm S -20°C of the crystalline resin constituting the support film is lower than the melting point Tm LCP of the liquid crystal polymer, it is considered that the liquid crystal polymer film layer can be stretched without breaking for the same reason.
• the total value of the yield load of the pair of support film layers is greater than the yield load of the liquid crystal polymer film layer over the entire temperature range of not less than temperature T S1 and not more than temperature T S2 .
• temperature T S2 is the melting point Tm LCP of the liquid crystal polymer, i.e., when the melting point Tm LCP of the liquid crystal polymer is lower than the melting point Tm S -20°C of the polymer constituting the support film layer, for example, when T S1 is 150°C, Tm LCP is 280°C, and Tm S is 320°C, it is preferable that the total value of the yield load of the pair of support film layers is greater than the yield load of the liquid crystal polymer film layer over the entire temperature range of T S1 (150°C) to T S2 (280°C).
• the temperature T S2 is the melting point Tm S -20°C of the polymer constituting the support film layer, that is, when the melting point Tm S -20°C of the polymer constituting the support film layer is lower than the melting point Tm LCP of the liquid crystal polymer, for example, when T S1 is 150°C, Tm LCP is 310°C, and Tm S is 320°C, it is preferable that the total value of the yield load of the pair of support film layers is larger than the yield load of the liquid crystal polymer film layer over the entire temperature range of T S1 (150°C) to T S2 (300°C). However, it is not necessary to satisfy the above relationship over the entire temperature range of T S1 or more and T S2 or less.
• the support film layer used in the present invention preferably has the following characteristic: the total value of the maximum point load of the pair of support film layers is preferably greater than the maximum point load of the liquid crystal polymer film layer at any temperature in the range of temperature Ts1 or more and temperature Ts2 or less. This allows the laminate of the liquid crystal polymer film layer and the support film layer to be stretched at a temperature equal to or lower than the melting point Tm LCP of the liquid crystal polymer when producing a liquid crystal polymer film laminate, thereby reducing the anisotropy of the liquid crystal polymer film finally obtained.
• the support film layer used in the present invention preferably has a breaking elongation of 200% or more in a temperature range of TS1 or more and TS2 or less. It is sufficient that at least one of the two support film layers laminated on the liquid crystal polymer film layer has a breaking elongation of 200% or more. This allows the laminate of the liquid crystal polymer film layer and the support film layer to be stretched at a temperature equal to or lower than the melting point Tm LCP of the liquid crystal polymer when producing the liquid crystal polymer film laminate of the present invention, thereby reducing the anisotropy of the liquid crystal polymer film finally obtained.
• the yield load, maximum load, and breaking elongation of the support film layer can be determined by conducting a tensile test on the support film used as the support film layer, obtaining an SS curve with the vertical axis representing stress and the horizontal axis representing elongation, and then determining the yield load, maximum load, and breaking elongation of the support film layer from the obtained SS curve.
• the liquid crystal polymer film layer and the support film layer must be in close contact with each other.
• the strength of the adhesion must be such that they do not peel off when the liquid crystal polymer film laminate is heated. Specifically, when the liquid crystal polymer film laminate is deformed at a bending angle of 120° relative to the surface of one of the support film layers and then deformed at a bending angle of 120° relative to the surface of the other support film layer, it is preferable that there is no peeling between the liquid crystal polymer film layer and the support film layer. If the liquid crystal polymer film layer and the support film layer peel off in this method, there is a risk that the liquid crystal polymer film layer will deform or break when the liquid crystal polymer film laminate is heated.
• the anisotropy of the molecular orientation of the liquid crystal polymer film obtained by peeling off the support film from the liquid crystal polymer film laminate of the present invention is preferably within a predetermined range of the degree of planar orientation as defined below.
• the planar orientation degree represented by the following formula (1) is preferably -0.5 or more and 0.5 or less.
• planar orientation degree is preferably -0.3 or more and 0.3 or less, more preferably -0.2 or more and 0.2 or less.
• the diffraction intensity of the 110 plane is the diffraction intensity of the crystal plane (110 plane) of the liquid crystal polymer.
• the integrated intensity is calculated by the area when ⁇ is plotted on the horizontal axis and the diffraction intensity on the vertical axis. If the value expressed by the above formula (1) is a positive value, it indicates that the molecular chains are oriented in the longitudinal direction, and if it is a negative value, it indicates that they are oriented in the width direction.
• the anisotropy of the linear expansion coefficient of the liquid crystal polymer film of the present invention can be reduced, and therefore, when the liquid crystal polymer film is laminated with copper to form an FPC, deformation due to the difference in linear expansion coefficient can be suppressed. In particular, this effect is more pronounced when the liquid crystal polymer film is subjected to heat treatment (described later).
• the value of the degree of planar orientation is preferably -0.2 to 0.2, and within this range, the linear expansion coefficient of the liquid crystal polymer film can be approximately 10 to 30 ppm in both the longitudinal and transverse directions of the film, and by setting the value of the degree of planar orientation to -0.1 to 0.1, the linear expansion coefficient becomes even closer to the linear expansion coefficient of copper, which is 18 ppm.
• the liquid crystal polymer film laminate of the present invention can be produced by a method including a laminate formation step of obtaining a laminate having a support film layer laminated on both sides of a liquid crystal polymer film layer, a stretching step of stretching this laminate in the longitudinal direction and/or the width direction, and a relaxation step of subjecting the laminate to a relaxation treatment under a temperature TR condition that satisfies the following formula (2): T R1 ⁇ T R ⁇ T R2 (2)
• T R1 represents a temperature that is the melting point of the liquid crystal polymer
• T R2 represents a temperature that is the melting point of the liquid crystal polymer, Tm LCP +20°C.
• the laminate of the liquid crystal polymer film layer and the support film layer is laminated by pressure lamination or heat lamination.
• the heat lamination method the liquid crystal polymer film layer and the support film layer are pressed together while the laminate of the liquid crystal polymer film layer and the support film layer is heated by a pair of heated rolls.
• the conditions in the heat lamination method can be appropriately selected according to the physical properties of the liquid crystal polymer and the crystalline resin constituting the support film layer. Although not particularly limited, it is preferable to perform heating and pressing at a temperature near the melting point Tm LCP of the liquid crystal polymer and at a temperature near the melting point Tm S of the crystalline resin constituting the support film.
• the surface treatment process in which the surface of the liquid crystal polymer film layer that comes into contact with the support film layer (the bonding surface) and the surface of the support film layer that comes into contact with the liquid crystal polymer film layer (the bonding surface) are each subjected to a surface treatment before the laminate formation process.
• Examples of the surface treatment method include plasma treatment in which a gas in a plasma state is irradiated onto the surface by applying electric energy, corona treatment in which the surface is activated by discharge, a method of activating the surface by irradiating ultraviolet rays or electron beams, a method of activating the surface by applying a flame, chemical treatment in which the surface is oxidized with potassium dichromate or the like, and primer treatment in which a primer is applied.
• the surface treatment method can be appropriately selected depending on the physical properties of the liquid crystal polymer and the crystalline resin, etc., but from the viewpoint of being able to increase the adhesion between the liquid crystal polymer film layer and the support film layer and to reduce damage to the liquid crystal polymer film obtained from the liquid crystal polymer film laminate, plasma treatment, corona treatment, and chemical treatment are preferred, and plasma treatment is particularly preferred.
• a laminate of a liquid crystal polymer film layer and a support film layer may be manufactured by a melt extrusion method.
• the liquid crystal polymer may be melted in a first extruder, and the crystalline resin may be melted in a second extruder, and the laminate may be formed by extruding each polymer into a film shape so that a layer of crystalline resin is laminated on one or both sides of the layer of liquid crystal polymer.
• a method for forming a multilayer extrusion film from a T-die can be used.
• examples include the feedblock method in which molten liquid crystal polymer and crystalline resin supplied from two extruders are fed to a feedblock, merged, and then extruded from a T-die in the form of a film, and the multi-manifold method in which molten liquid crystal polymer and crystalline resin are separately fed to a T-die, overlaid, and extruded in the form of a film. From the viewpoint of improving the smoothness of the final liquid crystal polymer film, it is preferable to apply the multi-manifold method, taking into consideration cases in which the liquid crystal polymer and crystalline resin have different viscosities and flow characteristics when melted.
• the laminate of the liquid crystal polymer film layer and the support film layer obtained in the laminate formation process is stretched in the longitudinal direction and/or the width direction.
• stretching in the width direction (TD direction) is preferable.
• the method of stretching the laminate is not particularly limited, but a tenter transverse stretching method in which both ends of the laminate are clamped with clips and heated and stretched is preferable.
• the stretching ratio and stretching speed are appropriately selected so that the support film layer can be stretched and the shape and physical properties of the liquid crystal polymer film layer after stretching are within the desired range.
• the stretching ratio is preferably 2 to 5 times.
• the stretching speed is preferably 1 to 10,000%/min, more preferably 50 to 5,000%/min, and even more preferably 500 to 4,000%/min.
• stretching in the longitudinal direction (MD direction) may be added as necessary.
• the temperature when stretching the laminate of the liquid crystal polymer film layer and the support film layer is preferably a temperature of T S1 or more and T S2 or less.
• T S2 is the melting point Tm LCP of the liquid crystal polymer, that is, when the melting point Tm LCP of the liquid crystal polymer is lower than the melting point Tm S of the crystalline resin constituting the support film layer -20 ° C.
• the temperature during stretching is preferably a temperature of T S1 or more, which is the glass transition temperature Tg of the liquid crystal polymer, and a temperature of Tm LCP or less, and more preferably a temperature of 120 to 340 ° C., and more preferably a temperature of 150 to 250 ° C.
• the smoothness of the liquid crystal polymer film finally obtained can be improved, and the film can be excellent in film formability without unevenness or streaks in thickness. Furthermore, it is more preferable to set the temperature at which the laminate is stretched to be equal to or higher than T S1 , which is the glass transition temperature Tg of the liquid crystal polymer, since the liquid crystal polymer film layer is easily stretched.
• the temperature during stretching is preferably equal to or higher than T S1 , which is the glass transition temperature Tg of the liquid crystal polymer, and equal to or lower than the melting point Tm S -20°C of the polymer constituting the support film, and more preferably, in the range of 120 to 320°C, and more preferably in the range of 150 to 230°C.
• the stretched laminate is subjected to a relaxation treatment at a temperature TR that satisfies the following formula (2).
• T R1 ⁇ T R ⁇ T R2 (2)
• T R1 represents a temperature that is the melting point of the liquid crystal polymer, Tm LCP -50°C
• T R2 represents a temperature that is the melting point of the liquid crystal polymer, Tm LCP +20°C.
• the relaxation treatment is a treatment in which the laminate after stretching is shrunk along the stretching direction under a predetermined temperature condition.
• the method of the relaxation treatment is not particularly limited, but for example, when the laminate is stretched by a tenter transverse stretching method, a method of appropriately reducing the distance between the clips of the tenter toward the downstream of the conveying direction of the laminate after stretching can be mentioned.
• the amount of relaxation in the width direction of the laminate by the relaxation treatment is preferably -2% to -15%, more preferably -5% to -12%, and even more preferably -10% to -12%.
• the amount of relaxation is expressed as the reduction ratio ((W 2 -W 1 )/W 1 ⁇ 100[%]) of the width (W 2 ) of the laminate after the relaxation treatment to the width (W 1 ) of the laminate after the stretching process.
• the time for the relaxation treatment is not particularly limited, and can be appropriately set depending on the temperature TR of the relaxation treatment and the target amount of relaxation.
• T R1 is the melting point of the liquid crystal polymer Tm LCP -50°C, preferably the melting point of the liquid crystal polymer Tm LCP -30°C, and more preferably the melting point of the liquid crystal polymer Tm LCP -10°C.
• the temperature TR in the relaxation treatment is the temperature of the surface of the laminate during the relaxation treatment.
• the temperature TR can be obtained by measuring the temperature of the surface of the laminate during the relaxation treatment.
• the temperature TR can be adjusted by appropriately adjusting the temperature inside the furnace of the stretching device during the relaxation treatment.
• the relaxation process may be continued until the target amount of relaxation is reached, and the duration of the relaxation process is not particularly limited, but is preferably 5 to 300 seconds, and more preferably 10 to 200 seconds.
• a liquid crystal polymer film laminate can be obtained.
• the dimensional change rate of the liquid crystal polymer film laminate before and after heating is 0% to -2%.
• the dimensional change rate is expressed as the reduction ratio ((W 3 -W 2 )/W 2 ⁇ 100[%])) of the width (W 2 ) of the liquid crystal polymer film laminate after heating to the width (W 2 ) of the liquid crystal polymer film laminate after relaxation treatment.
• the dimensional change rate is 0% to -2%, preferably 0% to -1%.
• the dimensional change rate due to heating is within the above range, it is possible to suppress the deformation of the liquid crystal polymer film layer when the liquid crystal polymer film laminate of the present invention is subjected to a heat treatment.
• the liquid crystal polymer film is heated for 5 to 600 seconds, it is sufficiently possible to evaluate the dimensional change rate before and after heating.
• the liquid crystal polymer film of the present invention can be produced by a method including a heat treatment step in which the liquid crystal polymer film laminate obtained by the above method is heat treated at a temperature T H that satisfies the following formula (3): By subjecting the liquid crystal polymer film laminate to heat treatment, a liquid crystal polymer film having excellent heat resistance can be produced.
• T H1 represents the melting point Tm LCP of the liquid crystal polymer ⁇ 80° C.
• T H2 represents the melting point Tm LCP of the liquid crystal polymer.
• T H is the temperature of the liquid crystal polymer laminate when heat-treated. Since the heat treatment time is long, the furnace temperature for heating the liquid crystal polymer laminate can usually be set as the heat treatment temperature T H.
• the outer side (outside) of the roll quickly reaches the furnace temperature after being put into the furnace, while the inner side (inside) of the roll takes time to reach the furnace temperature. For this reason, it is preferable to adjust the heating time and temperature program so that the temperature and heating time are the same on the outer side and the inner side of the roll.
• T H must be equal to or higher than the melting point Tm LCP -80°C (T H1 ) of the liquid crystal polymer, and if it is lower than Tm LCP -80°C, the heat treatment time for improving the heat resistance of the liquid crystal polymer film becomes long, resulting in reduced productivity. Also, if it exceeds the melting point Tm LCP (T H2 ) of the liquid crystal polymer, the liquid crystal polymer film will deform.
• T H1 is a temperature equal to the melting point Tm LCP -80°C of the liquid crystal polymer, and is preferably a temperature equal to the melting point Tm LCP -50°C of the liquid crystal polymer.
• the support film layer is peeled off to obtain a liquid crystal polymer film.
• the melting point Tm H-LCP (apparent melting point) of the liquid crystal polymer film is equal to or higher than Tm LCP due to the heat treatment. It is preferable to appropriately select the heat treatment temperature and time in the heat treatment step so that the melting point Tm H-LCP of the liquid crystal polymer film after the heat treatment is an optimal temperature depending on the application of the liquid crystal polymer film. For example, when the liquid crystal polymer film is used for a flexible printed wiring board, the melting point Tm H-LCP of the liquid crystal polymer film is preferably 300° C. or higher.
• the liquid crystal polymer film obtained in this manner has excellent heat resistance and can be suitably used for circuit boards such as flexible printed wiring boards.
• the support film layer of the liquid crystal polymer film laminate may be peeled off immediately before the liquid crystal polymer film is used.
• the support film layer can act as a protective film, for example, to prevent scratches during transportation.
• Planar orientation degree (integrated intensity in the longitudinal direction ⁇ integrated intensity in the width direction)/(integrated intensity in the longitudinal direction+integrated intensity in the width direction) (1)
• the endothermic peak temperature observed when the liquid crystal polymer film prepared in each example was heated from 0 ° C. to 10 ° C. / min was taken as the melting point Tm H-LCP of the liquid crystal polymer film.
• Tm H-LCP the melting point of the liquid crystal polymer film.
• the support film layer peeled from the laminated film consisting of the liquid crystal polymer layer and the support film layer was analyzed in the same manner, and the endothermic peak temperature observed when the temperature was raised from 0 ° C. to 10 ° C. / min was taken as the melting point of the support film layer.
• ⁇ Glass transition temperature Tg of liquid crystal polymer> A viscoelasticity measuring device (Hitachi High-Tech, model: DMA7100) was used to analyze the liquid crystal polymer film before lamination or the liquid crystal polymer film obtained by peeling the support film layer from a laminate film consisting of a liquid crystal polymer layer and a support film layer.
• the liquid crystal polymer film was measured in a tensile mode (frequency 10 Hz) from 30°C to 5°C/min, the peak temperature of the loss tangent (tan ⁇ ) associated with the change (decrease) in the storage modulus E' observed from 50°C to 150°C was taken as the glass transition temperature Tg of the liquid crystal polymer.
• Example 1 A liquid crystal polymer (LAPEROS A950RX, manufactured by Polyplastics Co., Ltd.) was fed into a twin-screw extruder (screw diameter 32 mm), extruded into a film form from a T-die (lip length 350 mm, lip clearance about 1 mm, die temperature 300°C) at the tip of the extruder, and cooled to obtain a liquid crystal polymer (LCP) film having a thickness of 200 ⁇ m to be used as a liquid crystal polymer film layer.
• LCP liquid crystal polymer
• the melting point Tm LCP of this film was evaluated by the above method.
• the melting point Tm LCP was 280°C.
• the glass transition temperature Tg was 95°C.
• the respective plasma-treated surfaces were overlapped, and a PEEK film was thermocompression-bonded to both sides of the liquid crystal polymer film using a first roll heated to 305 ° C.
• Ts1 (Tg) 95°C
• Ts2 280°C
• T R1 230°C
• T R2 300°C.
• the laminate of the liquid crystal polymer film and the PEEK film was stretched 3.5 times in the width direction (TD) at a conveying speed of 8 m/min (stretching speed 1667%/min) in a tenter-type transverse stretching machine (furnace temperature 320° C.).
• the temperature of the laminate during stretching was 210° C.
• the chuck interval of the tenter was linearly reduced while the laminate was held by the tenter, and a relaxation treatment was performed for 120 seconds.
• the amount of relaxation in the width direction of the laminate was ⁇ 11%, and the temperature T R of the laminate during the relaxation treatment was 280° C.
• the liquid crystal polymer film laminate was obtained.
• the liquid crystal polymer film laminate was evaluated for adhesion between the liquid crystal polymer film layer and the support film layer (PEEK film).
• Example 8 A liquid crystal polymer (LAPEROS C950RX, manufactured by Polyplastics Co., Ltd.) was fed into a twin-screw extruder (screw diameter 32 mm), extruded into a film form from a T-die (lip length 350 mm, lip clearance about 1 mm, die temperature 340°C) at the tip of the extruder, and cooled to obtain a liquid crystal polymer (LCP) film having a thickness of 200 ⁇ m to be used as a liquid crystal polymer film layer.
• LCP liquid crystal polymer
• the melting point Tm LCP of this film was evaluated by the above method.
• the melting point Tm LCP was 320°C.
• PEEK polyether ether ketone
• the plasma-treated surfaces were overlapped, and a PEEK film was thermocompressed onto both sides of the liquid crystal polymer film using a first roll heated to 305°C and a second roll heated to 120°C under conditions of a nip pressure of 0.2 MPa and a conveying speed of 0.5 m/min. After thermocompression, the liquid crystal polymer film and the PEEK film were in close contact.
• the laminate of the liquid crystal polymer film and the PEEK film was stretched 3 times in the width direction (TD) at a conveying speed of 8 m/min (stretching speed 1333%/min) in a tenter-type transverse stretching machine (furnace temperature 330° C.).
• the temperature of the laminate during stretching was 220° C.
• the chuck interval of the tenter was linearly reduced while the laminate was held by the tenter, and a relaxation treatment was performed for 120 seconds.
• the amount of relaxation in the width direction of the laminate was ⁇ 7%, and the temperature T R of the laminate during the relaxation treatment was 280° C.
• the liquid crystal polymer film laminate was obtained.
• the liquid crystal polymer film laminate was evaluated for adhesion between the liquid crystal polymer film layer and the support film layer (PEEK film).
• the liquid crystal polymer film laminate was wound into a roll, and this liquid crystal polymer film laminate was subjected to heat treatment at 280°C for 24 hours using an oven.
• the dimensional change rate of the liquid crystal polymer film laminate before and after the heat treatment was -1%.
• the PEEK film was peeled off to obtain a liquid crystal polymer film, and the shape, degree of planar orientation, and melting point (Tm H-LCP ) were evaluated. The results are shown in Table 1.
• Example 9 A liquid crystal polymer (LAPEROS A950RX, manufactured by Polyplastics Co., Ltd.) was fed into a twin-screw extruder (screw diameter 32 mm), extruded into a film form from a T-die (lip length 350 mm, lip clearance approximately 1 mm, die temperature 300°C) at the tip of the extruder, and cooled to obtain an unstretched liquid crystal polymer film having a thickness of 200 ⁇ m.
• the melting point Tm LCP and glass transition temperature Tg were evaluated by the above method.
• the melting point Tm LCP was 280°C, and the glass transition temperature Tg was 95°C.
• both sides of the unstretched liquid crystal polymer film were subjected to direct atmospheric pressure plasma treatment under an oxygen-containing gas atmosphere at a power of 1.5 kW and a conveying speed of 1.0 m/min.
• the laminate film thus produced was stretched 3 times in the width direction (TD) with a tenter-type transverse stretching machine (furnace temperature 280° C.) at a stretching zone length of 1.2 m and a conveying speed of 10 m/min (stretching speed 1667%/min).
• the temperature of the laminate during stretching was 150° C.
• the chuck interval of the tenter was linearly reduced at a furnace temperature of 240° C., and a relaxation treatment was performed for 120 seconds.
• the amount of relaxation in the width direction of the laminate was ⁇ 6%, and the temperature T R of the laminate during the relaxation treatment was 240° C.
• the liquid crystal polymer film laminate was obtained.
• the liquid crystal polymer film laminate was evaluated for adhesion between the liquid crystal polymer film layer and the support film layer (PEEK film).
• the liquid crystal polymer film laminate was wound into a roll, and this liquid crystal polymer film laminate was heat-treated in an oven at 240° C. for 24 hours. Thereafter, the PEEK film was peeled off to obtain a liquid crystal polymer film, and the shape, the degree of planar orientation, and the melting point (Tm H-LCP ) were evaluated. The results are shown in Table 1.
• Example 10 A liquid crystal polymer (Polyplastics Co., Ltd., LAPEROS A950RX) was supplied to a twin-screw extruder (screw diameter 26 mm) and melt-kneaded at 300 ° C.
• a polyether ether ketone (PEEK) polymer (Daicel-Evonik, VESTAKEEP 3300G) was supplied to a single-screw extruder (screw diameter 40 mm) as a support polymer and melt-kneaded at 380 ° C.
• PEEK polyether ether ketone
• molten polymers were supplied to a multi-manifold T-die, and a layer of a support polymer was superimposed on both sides of a layer of a liquid crystal polymer, extruded, and cooled to produce a laminated film with a liquid crystal polymer layer of 175 ⁇ m and support polymer layers on both sides of 30 ⁇ m each, for a total of 235 ⁇ m.
• the melting point of PEEK was 340 ° C.
• the laminate film thus produced was stretched 3.5 times in the width direction (TD) with a tenter-type transverse stretching machine (furnace temperature 330° C.) at a stretching zone length of 1.2 m and a conveying speed of 5 m/min (stretching speed 1042%/min).
• the temperature of the laminate during stretching was 260° C.
• the chuck interval of the tenter was linearly reduced at a furnace temperature of 280° C., and a relaxation treatment was performed for 120 seconds.
• the relaxation amount in the width direction of the laminate was ⁇ 11%, and the temperature T R of the laminate during the relaxation treatment was 280° C.
• the liquid crystal polymer film laminate was obtained.
• the liquid crystal polymer film laminate was evaluated for adhesion between the liquid crystal polymer film layer and the support film layer (PEEK film).
• the liquid crystal polymer film laminate was wound into a roll, and this liquid crystal polymer film laminate was heat-treated in an oven at 250° C. for 24 hours. Thereafter, the PEEK film was peeled off to obtain a liquid crystal polymer film, and the shape, the degree of planar orientation, and the melting point (Tm H-LCP ) were evaluated. The results are shown in Table 1.
• Example 1 A liquid crystal polymer (LAPEROS A950RX, manufactured by Polyplastics Co., Ltd.) was fed into a twin-screw extruder (screw diameter 32 mm), extruded into a film form from a T-die (lip length 350 mm, lip clearance approximately 1 mm, die temperature 300°C) at the tip of the extruder, and cooled to produce a liquid crystal polymer film, which was wound into a roll and placed in an oven and heat-treated at a temperature of 250°C for 24 hours.
• the liquid crystal polymer film after heat treatment was evaluated in the same manner as in Example 1.
• the amount of shrinkage during heat treatment was calculated as the ratio of the reduction in the width of the liquid crystal polymer film after heat treatment to the width of the liquid crystal polymer film before heat treatment. The results are shown in Table 1.
• Example 2 A liquid crystal polymer film laminate was obtained in the same manner as in Example 1, except that the liquid crystal polymer film and the polyether ether ketone (PEEK) film as the support film layer were not subjected to atmospheric pressure plasma treatment. However, the liquid crystal polymer film and the PEEK film were not adhered to each other, and holes and cracks were observed in the liquid crystal polymer film.
• PEEK polyether ether ketone
• Example 3 A liquid crystal polymer film was obtained in the same manner as in Example 1, except that the relaxation treatment was not performed, and was evaluated in the same manner as in Example 1.
• the amount of shrinkage during heat treatment was calculated as the ratio of the reduction in the width of the liquid crystal polymer film after heat treatment to the width of the liquid crystal polymer film before heat treatment. The results are shown in Table 1.
• Example 5 A liquid crystal polymer film laminate was obtained in the same manner as in Example 1, except that the temperature TR of the relaxation treatment was changed to 310° C. However, since the liquid crystal polymer melted after the relaxation treatment and the shape was deteriorated, it was not possible to perform the subsequent evaluation.
• a liquid crystal polymer film laminate having a pair of support film layers laminated on both sides of a liquid crystal polymer film was stretched and then relaxed, and the liquid crystal polymer film obtained using the liquid crystal polymer film laminate had a dimensional change rate of 0% to -2% when heated at a temperature in the range of Tm LCP -80°C to Tm LCP of the liquid crystal polymer.
• the liquid crystal polymer film had a good shape after heat treatment and was also excellent in heat resistance.
• Comparative Example 1 in which the heat treatment was performed without laminating with a support film layer, the film was deformed by the heat treatment, and the rolled films were fused together.
• Comparative Example 2 in which the liquid crystal polymer film and the PEEK film were not in close contact with each other, holes and cracks were observed in the liquid crystal polymer film of the obtained liquid crystal polymer film laminate.
• Comparative Example 3 in which the relaxation treatment was not performed, and Comparative Example 4, in which the temperature T R during the relaxation treatment was lower than the melting point Tm LCP -50°C of the liquid crystal polymer, the dimensional change rate when heated to a temperature range from the melting point Tm LCP -80°C of the liquid crystal polymer to Tm LCP was less than -2%, and the width of the liquid crystal polymer film was greatly shrunk by the heat treatment, and the liquid crystal polymer film was deformed.

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