JPS6135936B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a polyester laminated film. More specifically, the present invention relates to a method for producing a polyester laminated film that has excellent mechanical properties, electrical properties, heat resistance, chemical resistance, dimensional stability, and other properties. 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. 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, but they do not have sufficient heat resistance; for example, stretched polyethylene terephthalate films shrink even at temperatures below their melting point, such as 230°C. The range of use is severely limited due to the high rate of use, and the chemical resistance and dimensional stability are also inferior compared to, for example, thermosetting resins. In addition, although polyimide film has excellent mechanical properties and heat resistance, it has a high equilibrium moisture content, does not have good dimensional stability and electrical properties, and has poor adhesion with metal layers. It requires a heat-resistant adhesive that can sufficiently exhibit the heat resistance of the base film, and furthermore, it is very expensive because it uses a solution casting method. Furthermore, the cost is also high because this heat-resistant adhesive is manufactured and used industrially. Furthermore, glass-epoxy film is a thermosetting resin and has the disadvantage of having low elongation and lack of flexibility. The present inventor focused on this point and created a polyester base material that possesses the melt moldability and excellent electrical properties of a substantially linear saturated polyester, and which can have heat resistance comparable to that of a curable resin after film formation. As a result of intensive studies to obtain a laminated film with excellent heat resistance and flexibility for use as a film, we decided to directly coat a conductive metal foil onto a linear polyester film that had been melt-blended and then melt-cast with specific photopolymerization properties. Crimp lamination,
Next, it was discovered that a laminated film obtained by subjecting the base film to actinic radiation treatment has excellent adhesion between the base film and the metal foil layer, as well as excellent heat resistance and flexibility, and has thus arrived at the present invention. That is, the present invention provides a substantially linear polyester represented by the following formula (i). [However, in the formula, R ₁ , R ₂ and R ₃ are the same or different and each represents a member selected from the group consisting of a hydrogen atom and a monovalent hydrocarbon group. ] A conductive metal layer is directly pressure-bonded and laminated onto a film that is melt-mixed with a photoreaction initiator and a compound having a photopolymerizable unsaturated group that is stable under melt-mixing and film-forming conditions, and then melt-formed. This method of producing a polyester laminated film is characterized in that the polyester film layer is then crosslinked by ultraviolet irradiation treatment. Examples of acid components constituting the substantially linear polyester used in the present invention include terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenylsulfonedicarboxylic acid, diphenoxyethanedicarboxylic acid, and diphenyldicarboxylic acid. Aromatic dicarboxylic acids such as enyl ether dicarboxylic acid, methyl terephthalic acid, and methyl isophthalic acid; Aliphatic dicarboxylic acids such as succinic acid, adipic acid, and sebacic acid; Alicyclic dicarboxylic acids such as hexahydroterephthalic acid; ε-oxycaprone Examples include oxycarboxylic acids such as oxybenzoic acid and hydroxyethoxybenzoic acid, and aromatic dicarboxylic acids, particularly terephthalic acid and isophthalic acid, are preferred. Examples of glycol components of polyester include ethylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, decamethylene glycol, neopentylene glycol, and cyclohexane dimethylol. In particular, ethylene glycol,
Preferred are tetramethylene glycol, neopentylene glycol, and cyclohexane dimethylol. The substantially linear polyester can be obtained by polycondensation of the above dicarboxylic acid component and glycol component, and a conventionally known method can be used for its production. These polymers are preferably copolymers rather than homopolymers; for example, copolymers using two or more types of acid components or two or more types of glycol components are preferable, and copolyesters having ethylene terephthalate as a main repeating unit are particularly preferable. Preferred copolymerization components of this copolyester include isophthalic acid and neopentylene glycol. The copolymerization ratio of these is 50 mol% or less based on the total acid component, and more preferably 4 to 4% by mole.
It is preferably 30 mol%, particularly 8 to 20 mol%. The above-mentioned polyester may be copolymerized with a polyfunctional compound such as pentaerythritol, trimethylolpropane, pyromellitic acid, and ester-forming derivatives thereof within a substantially linear range. The polyester used in the present invention mainly consists of the above linear polyester, and a crosslinking agent, that is, a compound having a photopolymerizable unsaturated group that is substantially stable under the melt film forming conditions of the polyester, and a photoreaction initiator are melted into this. After blending, melt film formation is performed. Here, "substantially stable under polyester melt-mixing/film-forming conditions" means the temperature at which polyester melts, for example, 20 degrees below the melting point (Tm) of polyester.
This means that when the polyester is maintained in an inert gas at a high temperature for about 15 minutes, for example, no reaction occurs between the unsaturated groups or between the unsaturated groups and the polyester, and the unsaturated groups are stably present. A photopolymerizable unsaturated group that satisfies these conditions is a group represented by the following formula. [However, in the formula, R ₁ , R ₂ and R ₃ are the same or different and each represents a member selected from the group consisting of a hydrogen atom and a monovalent hydrocarbon group. ] In the above general formula, for R ₁ , R ₂ and R ₃ , preferred examples of monovalent hydrocarbon groups include C ₁ to C ₆ alkyl, more preferably C ₁ to _{C 3} alkyl. can. Among the groups represented by the above formula, ie, allyl or substituted allyl, preferred are allyl, metaallyl and crotyl groups,
Particularly preferred is an allyl group. Incorporation of such a photopolymerizable unsaturated group into the polyester can be achieved by melt-mixing a compound having the photopolymerizable unsaturated group (hereinafter sometimes referred to as compound (A)) with the polyester.
When blending compound (A) with polyester, it is of course important that the unsaturated groups in the compound (A) are stable under melt-kneading with the polyester;
It is preferable that the compound itself is also stable;
When (A) is melt-blended, the resulting composition contains a phenol/tetrachloroethane mixed solution at 35°C.
It is preferable that substantially no insoluble matter is generated and the intrinsic viscosity [η] of the polyester is not significantly reduced. Therefore, compounds that decompose or gasify at the melting temperature of polyester are not preferred as blending compounds. Therefore, from the point of view of gasification, the vapor pressure at the melting temperature of polyester must be 100 mmHg or less, especially 10 mmHg.
The following compounds are preferred. Specific examples of the compound (A) containing the group represented by the above general formula are listed below. [] Compounds having an amide bond and/or an imide bond: For example, N・N′・N″-triallyltrimesic acid amide, N・N・N′-triallyl trimellitic acid amide imide, N・N・
N′・N′・N″・N″-hexaallyltrimesic acid amide. [] Compounds having an ester bond: diallyl terephthalate, diallyl isophthalate, diallyl benzophenonedicarboxylate, triallyl trimellitate. [] Cyanuric acid or derivatives of isocyanuric acid: triallyl cyanurate, triallyl isocyanurate, tetramethylenebis[diallyl isocyanurate]. The allyl group of the specific compounds of [], [], and [] above may be a crotyl group or a metaallyl group. [] Compounds containing epoxy groups: (1) Diallylglycidyl cyanurate, diallylglycidyl isocyanurate; these allyl groups are replaced with crotyl or methallyl groups, and the glycidyl groups are replaced with 2,3-epoxy-2-methylpropyl groups. , 2,3-epoxybutyl group,
Cyanuric acid or isocyanuric acid derivatives substituted with 2,3-epoxy-2-methyl-butyl groups, etc. (2) N-allylglycidyloxybenzamide, N・N′-diallyl (or N・N・N′・
N'-tetraallyl)-3,4-epoxycyclohexane 1,2-dicarboxamide; convert these allyl groups to crotyl or methallyl groups, or convert glycidyl groups to 2,3-epoxy-
Aliphatic, alicyclic, aromatic amide or imide compounds substituted with 2-methylpropyl group, 2,3-epoxybutyl group, 2,3-epoxy-2-methylbutyl group, etc. (3) For example, 2,2-bis(3-allyl-4-
glycidyloxyphenyl)propane; (2
-allylphenyl)-glycidyl ether;
These allyl groups are changed to crotyl group or meta-allyl group, and the glycidyl group is changed to 2.
3-epoxy-2-methylpropyl group, 2.
3-epoxybutyl group, 2,3-epoxy-
Compounds in which the aromatic nucleus is substituted with an allyl group and a glycidyloxy group, such as a compound substituted with a 2-methyl-butyl group, etc. The compound having a photopolymerizable unsaturated group that can be blended with the polyester mentioned above has two or more groups represented by the above general formula, and when subjected to the ultraviolet treatment described below, a stronger crosslinked structure is formed in the film layer. It is preferable because it can be obtained in Among these, the above-mentioned compounds [], [] or [] are more preferred, and the compounds [] and [] are particularly preferred.
Among [ ], compounds having four or more unsaturated groups are more preferred. In addition to the photopolymerizable unsaturated group-containing compounds mentioned above, a photoreaction initiator is also used as a crosslinking agent. Preferred examples include ketones, benzyl and its derivatives, benzoin and its derivatives, and polynuclear quinones. Preferred examples of such compounds include benzophenone, benzyl, benzyl dialkyl ketal, benzoin, benzoin ether, and substituted derivatives thereof such as alkyl, nitro, and alkoxy, and substituted derivatives such as anthraquinone. In addition to the photoinitiators mentioned above, German published patent specifications No. 1769168, No. 1769853, No. 1807297,
Among the photoreaction initiators listed in Nos. 1807301, 1919078, and 1949010, those that are substantially stable during the melting of polyester can be used as appropriate. Further, for example, benzophenone-4,4'-dicarboxylic acid or the like may be copolymerized with the polyester.
Among these photoreaction initiators, benzyl and its derivatives are preferred, and benzyl derivatives are particularly preferred because of their high activity. Further, among aromatic ketones, compounds having two or more benzophenone residues are also preferred since they have high activity. Among these photoreaction initiators, substituted derivatives of benzyl ketals and benzoin ethers, such as benzyl dimethyl ketal and benzoin ethyl ether, are particularly preferred. Further, a compound having both the above-mentioned aliphatic unsaturated group and photoreaction initiating function can also be used as a preferable photoreaction initiator, and examples of compounds having such two types of functions include, for example, N-allyl. (or crotyl or metaallyl) benzoylbenzamide, N-allyl (or crotyl or metaallyl) anthraquinone carboxamide, N-
Allyl (or crotyl or metaallyl) benzoyl phthalimide, N·N-diallyl (or dicrotyl or dimethallyl) benzoylbenzamide, N·N'-diallyl (or dicrotyl or dimethallyl) benzophenone tetracarboximide, and the like. The polyester used for producing the laminated film of the present invention is melt-formed after containing the above-mentioned crosslinking agent. In the case of a compound containing a photopolymerizable unsaturated group, the amount of the crosslinking agent added is about 0.01 to 0.5 equivalent as a photopolymerizable unsaturated group per 100 g of polymer, more preferably 0.03 equivalent.
~0.4 equivalents, particularly preferably 0.06 to 0.3 equivalents, and the amount of photoreaction initiator added is approximately 0.01 to 20 parts by weight, preferably 0.05 to 10 parts by weight, more preferably 0.05 to 10 parts by weight, based on 100 parts by weight of the polyester. 0.1~5
Parts by weight, particularly preferably about 0.1 to 3 parts by weight. The polyester film used in the present invention is produced by melt-blending a polyester containing a predetermined amount of a photopolymerizable unsaturated group and a photoreaction initiator, and forming a film of a desired thickness by melt-blending the polyester. Obtained by doing. When a photopolymerizable unsaturated group and a photoinitiator are incorporated into polyester by melt blending,
Usually, polyester, a compound having a photopolymerizable unsaturated group, and a photoreaction initiator are mixed using a mechanical mixing means such as an 8-type blender or a V-type blender, and then a kneader such as an extruder is used to mix the two. The mixture is uniformly blended at or above the temperature at which the polyester becomes molten, preferably at or about 60° C. above the melting point of the polyester. It can then be melted and easily formed into a film by continuous extrusion or other conventional thermoplastic resin molding methods. In addition, as another method of blending, after melting the polymer using a melt extruder or a kneader, the crosslinking agent is metered and supplied in conjunction with a measuring meter for the melt-supplied polymer. A method of kneading a predetermined amount can also be used. For example, a predetermined amount of crosslinking agent is introduced into the cylinder portion of the melted polymer using a melt extruder, preferably a twin-screw extruder rotating in opposite directions, or a co-kneader, using a metering pump, and then preferably using a screw with a dullage, a static mixer, or the like. A method of kneading using a mixture can be used. In the present invention, the polymer composition kneaded as described above is melt-extruded through a slit such as a sheet die, and is cooled and solidified to obtain a film-like molded product of the base polymer. In the present invention, the base polymer film thus obtained is pressure-bonded with a conductive metal to obtain a composite film consisting of a conductive metal layer and a base polymer layer. As the conductive metal layer in the present invention, copper aluminum or the like is 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 preferably used. Particularly when flexibility is required, rolled copper foil is preferably used. Such metal foils are readily available on the market as foils with a thickness of 5 μm or more, preferably 15 μm or more. These conductive metal foils are used to improve adhesion with the base polymer described below.
It is preferable that the surface on the crimping side is chemically or physically roughened. Such surface roughening may be performed by conventionally known methods and techniques, and is an easy processing method for those skilled in the art. The laminated film of the present invention is a composite film consisting of a base polymer layer and a conductive metal layer, which is obtained by pressing the polyester base film containing the crosslinking agent and a conductive metal foil together using a pressure hot roller or a laminator. The base polymer layer and the conductive metal layer are combined after the base polymer sheet is molded and before the polymer is crosslinked, for example, by the so-called extrusion lamination method in which the polymer is laminated with the metal foil during melt extrusion. , a method is used in which the polymer is melt-extruded to form a sheet and then pressed onto the metal foil using a pressure hot roller. In the extrusion lamination method described above, in order to improve the adhesion between the polymer layer and the metal layer, after casting the polymer on the metal foil, pressurization is applied when the temperature of the polymer reaches the predetermined temperature described below. It is preferable to press with a hot roller. The temperature (TH: °C) at which the base polymer and metal foil are bonded using a pressure hot roller is determined by the following formula, expressed as the weight % (W) of the compound having a photopolymerizable unsaturated group in the polymer. It is preferable to carry out within a range. 0.89W ² -24W+250TH-6W+250 TH40 Crimp pressure is 2Kg/cm2 or ^more , preferably 3Kg/cm2 or more
cm ² , particularly preferably 5Kg/cm ² or more, 250Kg/cm ² or less, preferably 200Kg/cm ² or less, and even more preferably 150Kg/cm 2
cm ² or less, particularly preferably 100 Kg/cm ² or less, and the pressing time with the roller is preferably 0.5 seconds or more, more preferably 1 second or more. Furthermore, although the conditions are within the above-mentioned conditions, it is desirable that the crimping conditions be changed depending on the surface material of the roll. The surface material of the roll is
It particularly affects the appearance of the outer surface of the polymer layer of the composite film obtained by crimping. Such material must be able to withstand long-term continuous use at the compression temperature TH. Specific examples include hard-plated polishing rolls, silicone rubber-lined rolls, and Teflon-lined rolls. In order to heat and press the composite film more effectively, it is also possible to use multistage rollers with different heating temperatures, pressures, etc. The laminated film of the present invention is produced by irradiating the base polyester with ultraviolet rays and crosslinking the composite as described above. The ultraviolet irradiation conditions are room temperature to a temperature lower than the decomposition temperature of polyester (°C), preferably the second order transition point (Tg) to the melting point (Tm) of polyester.
(℃), more preferably (Tg+10) to Tm
(℃), more preferably (Tg+10) to (Tm-10)
at a temperature of 1 second to 10 hours, preferably 2 seconds to 1 hour, more preferably 5 seconds to 30 minutes, particularly preferably
10 seconds to 10 minutes. The composite film subjected to the pressure crosslinking treatment as described above can be used as it is, but it should also be heated at a temperature of 150°C or higher, preferably 180°C or higher, particularly preferably 210°C or higher.
The adhesion can be further improved by heat treatment for 10 seconds or more, preferably 30 seconds or more, more preferably 1 minute or more, and 60 minutes or less, preferably 30 minutes or less. Although this heat treatment can be performed under hot air, it is preferable to apply infrared heating from the polymer layer side in order to suppress oxidation of the composite metal foil. The polyester film layer used in the present invention can also contain reinforcing materials and reinforcing agents such as glass cloth glass fiber, mica, and talc. In this case, the purpose can be easily achieved by mixing a reinforcing agent together with a crosslinking agent and an initiator, and performing a composite crosslinking treatment as described above after melt extrusion. The laminated film produced by the method of the present invention has excellent heat resistance and dimensional stability, and even
Soldering at temperatures above 300℃ is possible, and the adhesion between the metal layer and the base polymer layer is high, with a peel strength of 1Kg/cm or more, and even 1.5Kg/cm.
This results in an excellent composite film. The laminated film of the present invention can be effectively applied to materials that require heat resistance and flexibility, such as flexible blueprint circuits, table carrier surface heating elements, and the like. The present invention will be explained in more detail below with reference to Examples. In the examples, "part" means "part by weight", and the intrinsic viscosity is a value measured at 35°C in a mixed solution of phenol/tetrachloroethane (weight ratio 60/40). The peel strength was measured using an Instron tensile tester at a tensile rate of 1 cm/min. Solder heat resistance was measured according to JIS-C-6481 (Test method for copper-clad laminates for printed circuits). Examples 1 to 4 Polyethylene terephthalate (intrinsic viscosity 0.74) copolymerized with 15 mol% isophthalic acid was sufficiently dried and then metered and fed to a 30 mmφ counter-rotating twin-shaft ruler equipped with a vent, melted in the cylinder, and the vent part The crosslinking agent and photoinitiator shown in Table 1 are introduced into the Ruder using a metering pump, the molten polymer and additives are intimately blended,
The homogeneous blend was then led to a T-die section and extruded onto a cooling drum to obtain a transparent amorphous film with a thickness of about 100 microns. This film and a copper foil with a thickness of 35 μm, which is used for printed wiring boards and which is not coated with adhesive, are pressed together using two hot rollers lined with silicone rubber under the conditions shown in Table 1. The polyester film layer was crosslinked by UV irradiation for 3 minutes at a distance of 20 cm under a 2KW high-pressure mercury lamp (30W/cm). Next, a heat treatment was performed at the temperatures shown in Table 1 to obtain a laminated film. The peel strength of this laminated film was measured and
A solder immersion test was conducted at 260°C for 30 seconds. The results are shown in Table 1. Examples 5 and 6 Polyethylene terephthalate (intrinsic viscosity 0.72) copolymerized with 15 mol% of isophthalic acid and 20 mol% of neopentylene glycol was used in the same manner as in Example 1, and the specified crosslinking agent and light shown in Table 1 were added. A reaction initiator was blended and a film was further formed. Furthermore, a laminated film was obtained in the same manner as in Example 1 using the obtained film. The peel strength of this laminated film was measured and a solder dipping test was conducted. The results are shown in Table 1. Comparative Examples 1, 2 Polymer of Example 1 (Comparative Example 1) or Example 5
An attempt was made to press a copper foil onto a film obtained in the same manner as in Example 1 or Example 5, except that no crosslinking agent or photoinitiator was added to the polymer (Comparative Example 2). It hardly came into contact with the foil.

[Table] Examples 7 to 10 After sufficiently drying polyethylene terephthalate (intrinsic viscosity 0.67) copolymerized with 20 mol% isophthalic acid, it was melted with the crosslinking agent and photoinitiator shown in Table 2 in the same manner as in Example 1. After blending, the intimate blend was melt-cast to obtain a transparent amorphous film with a thickness of about 100 μm. Using this film, a laminated film was obtained in the same manner as in Example 1 (however, a 4KW high-pressure mercury lamp was used). Table 2 shows the properties of the obtained laminated film.

[Table] Examples 11 to 14 Polyethylene terephthalate (intrinsic viscosity 0.74) copolymerized with 15 mol% of isophthalic acid was thoroughly dried, then metered and fed to a 30 mmφ counter-rotating twin-shaft ruler equipped with a vent, melted in the cylinder, On the other hand, the crosslinking agent and photoinitiator shown in Table 3 are introduced into the Ruder from the vent part using a metering pump, and the molten polymer and additives are intimately blended.
The homogeneous blend was then led to a T-die section and extruded onto a cooling drum to obtain a transparent amorphous film with a thickness of about 100 microns. This film (p), a commercially available flat glass cloth (G) with a thickness of 30μ, and a copper foil (M) without adhesive and a thickness of 35μ used for printed wiring boards are lined with silicone rubber. 2
Press with a hot roller under the conditions shown in Table 3, and then apply a 2KW polyester film layer.
Crosslinking was carried out by irradiating ultraviolet light for 3 minutes at a distance of 20 cm under a high-pressure mercury lamp (30 W/cm). Next, a heat treatment was performed at the temperatures shown in Table 3 to obtain a laminated film.
The peel strength of this laminated film was measured,
A solder dipping test was also conducted at 260°C for 30 seconds. The results are shown in Table 3. Examples 15 and 16 Polyethylene terephthalate (intrinsic viscosity 0.72) copolymerized with 15 mol% isophthalic acid and 20 mol% neopentylene glycol was used in the same manner as in Example 11, and the specified crosslinking agent and light shown in Table 3 were added. A reaction initiator was blended and a film was further formed. Furthermore, a laminated film was obtained in the same manner as in Example 11 using the obtained film. The peel strength of this laminated film was measured and a solder dipping test was conducted. The results are shown in Table 3.

【table】

Claims (1)

[Claims] 1 Substantially linear polyester formed by the following formula [However, in the formula, R ₁ , R ₂ and R ₃ are the same or different and each represents a member selected from the group consisting of a hydrogen atom and a monovalent hydrocarbon group. ] A conductive metal layer is directly pressure-bonded and laminated onto a film that is melt-mixed with a photoreaction initiator and a compound having a photopolymerizable unsaturated group that is stable under melt-mixing and film-forming conditions, and then melt-formed. and then crosslinking the polyester film layer by ultraviolet irradiation treatment.