Insulating coating material with excellent wear resistance
阅读说明：本技术 耐磨耗性优越的绝缘包覆材料 (Insulating coating material with excellent wear resistance ) 是由 近藤康孝 多和田诚 小野和宏 于 2015-11-17 设计创作，主要内容包括：本发明的目的是提供耐磨耗性优越的绝缘包覆材料。通过提供以下(1)～(3)的绝缘包覆材料能够解决上述课题。(1)具备具有特定的耐刮破特性及厚度的绝缘膜的绝缘包覆材料,(2)具备应力应变曲线中塑性变形时的应力x与形变a由特定式表示的绝缘膜的绝缘包覆材料,以及(3)具备环刚度值a与绝缘膜厚度b满足特定关系的绝缘膜的绝缘包覆材料。(The invention aims to provide an insulating coating material with excellent wear resistance. The above problems can be solved by providing the following insulating coating materials (1) to (3). (1) An insulating coating material having an insulating film with a specific scratch resistance and thickness, (2) an insulating coating material having an insulating film in which stress x and strain a at the time of plastic deformation in a stress-strain curve are expressed by a specific formula, and (3) an insulating coating material having an insulating film in which a ring stiffness value a and an insulating film thickness b satisfy a specific relationship.)
1. An insulating coating material, characterized in that: comprises an insulating film and an adhesive layer, wherein the adhesive layer is provided on at least one surface of the insulating film; the yield strength of the insulating film obtained from the stress-strain curve obtained in the tensile elastic modulus measurement is 160MPa or more, and the stress x (MPa) and the strain a (%) of the insulating film in the plastic deformation region satisfy the following formula (1),
the insulating film is made of polyimide and is formed of polyimide,
the acid dianhydride component of the whole polyimide contains 0 to 80 mol percent of PMDA, 10 to 27 mol percent of BTDA and 0 to 87 mol percent of BPDA,
the diamine component of the whole imide contains 50 to 100 mol% of p-PDA, 0 to 50 mol% of ODA, and 0 to 12 mol% of BAPP,
2.6×a+175＜x＜6.0×a+370…(1)。
2. the insulating cladding material of claim 1, wherein: the scratch resistance was 2.0 times or more.
3. The insulating cladding material according to claim 1 or 2, wherein: the thickness of the insulating film is 25 μm or less.
4. The insulating coating material according to claim 1 or 2, wherein the insulating film is a polyimide film.
5. The insulating cladding material according to claim 1 or 2, wherein: the adhesive layer contains a fluororesin.
6. An insulated cable or an insulated lead, characterized in that: the insulating coating material according to claim 1 or 2 is formed by winding the insulating coating material around a wire.
Technical Field
The present invention relates to an insulating coating material and use thereof, and particularly to an insulating coating material having excellent abrasion resistance used for an aerospace wire, cable, or the like.
Background
A coating material used for an aerospace wire or cable is required to have not only heat resistance, electrical insulation, chemical resistance, and flame retardancy, but also durability characteristics such as Abrasion resistance (Abrasion resistance) and puncture resistance (cut resistance).
For example, as a technique for an aerospace wire or the like, a multilayer polyimide-fluoropolymer insulation structure, an insulated lead wire/cable, and the like, which exhibit excellent cut resistance, have been developed (for example,
Regarding the multilayer polyimide fluoropolymer insulating material,
Patent document 2 uses an Apical AV as an insulating film for an insulating coating material, mainly for the purpose of improving heat seal strength. However, no specific evaluation of abrasion resistance is described.
Patent document 3 addresses the improvement of abrasion resistance (frictional wear), and discloses that the most excellent abrasion resistance is 111 times when a thin polyimide film of 0.65 mil is used.
Patent document 4 discloses a wire-wound composition including a polyimide layer and a fluororesin adhesive layer. Although the scratch (abrasion) characteristics are disclosed, the characteristics are not evaluated.
Currently, Oasis manufactured by dupont (Du Pont) and apical (type af) manufactured by kaneka north America are known as insulating coating materials.
(Prior art document)
Patent document 1: japanese published patent application publication No. 10-100340 (published 4/21 (1998)) "
Patent document 2: U.S. patent publication No. 2010/0282488
Patent document 3: U.S. Pat. No. 7022402
Patent document 4: japanese published patent application publication No. JP 2013-512535 (published 4/11/2013) "
Patent document 5: U.S. Pat. No. 7018704
Disclosure of Invention
(problems to be solved by the invention)
Among the above-described durability characteristics required for the insulating coating material, abrasion resistance is an important characteristic. In particular, from the viewpoint of ensuring safety, it can be said that the higher the abrasion resistance, the better the insulating coating material used for aerospace wires, cables, and the like. For example, since the insulating coating material needs to be able to withstand friction when the electric wire and the cable are installed in an aircraft and friction caused by vibration during flight, importance is attached to wear resistance when the insulating coating material is used for aerospace.
Further, an insulating coating material used for a wire of an aerospace wire such as an airplane, a cable, or the like is required to have lightweight properties, and in recent years, there is an increasing demand for lightweight properties, and a thinner insulating coating material is required. Therefore, development of a thinner insulating coating material having excellent abrasion resistance is urgently required. However, an insulating material having sufficiently excellent abrasion resistance and a thin thickness, which can satisfy recent high demand, has not been developed yet.
Accordingly, an object of the present invention is to provide an insulating coating material which is used for an aircraft aerospace wire, a cable wire, and the like, and which is excellent in wear resistance and has a small thickness.
(means for solving the problems)
In view of the above, the present inventors have made extensive studies and completed an insulating coating material of the present invention which comprises an insulating film and an adhesive layer and has the adhesive layer on at least one surface of the insulating film. That is, the present invention can solve the above problems by the following novel insulating coating material and an insulated cable or an insulated lead using the insulating coating material.
As another embodiment, the present inventors have paid attention to a stress-strain curve obtained when the tensile elastic modulus of an insulating film constituting an insulating coating material is measured and a ring stiffness value of the insulating film constituting the insulating coating material, and have made intensive studies to solve the above problems, and as a result, have found that the above problems can be solved by the following novel insulating coating material and an insulated cable using the same, and have completed the present invention.
1) The invention relates to an insulating coating material, which is characterized in that: comprises an insulating film and an adhesive layer, wherein the adhesive layer is provided on at least one surface of the insulating film; the scratch resistance of an integrated laminate formed by laminating components in the order of insulating coating material/lead wire/insulating coating material in such a manner that the adhesive layer of the insulating coating material is in contact with the lead wire is 3.0 times or more, and the thickness of the insulating film is 20 [ mu ] m or less
2) The invention relates to an insulating coating material, which is characterized in that:
comprises an insulating film and an adhesive layer, wherein the adhesive layer is provided on at least one surface of the insulating film; the yield strength of the insulating film obtained from the stress-strain curve obtained in the tensile elastic modulus measurement is 160MPa or more, and the stress x (MPa) and the strain a (%) of the insulating film in the plastic deformation region satisfy the following formula (1),
2.6×a+175＜x＜6.0×a+370…(1)
3) the invention relates to an insulating coating material, which is characterized in that: comprises an insulating film and an adhesive layer, wherein the adhesive layer is provided on at least one surface of the insulating film; in the relational expression (1) between the ring stiffness value a (g/cm) of the insulating film and the thickness b (μm) of the insulating film, k is 0.000105 or more,
a＝k×b3… type (1)
(Effect of the invention)
When the insulating coating material of the present invention is wound around a conductor to form an insulated conductor, the insulating coating material is sufficiently excellent in wear resistance and can satisfy recent high demands, and therefore, it is possible to provide an insulating coating material which is excellent in wear resistance even when the insulating coating material is made thin and lightweight.
Drawings
FIG. 1 is a schematic cross-sectional view of a laminate of the present invention.
Fig. 2 is a graph showing stress-strain curves of example B of the present invention and comparative example B.
Fig. 3 is a partially enlarged view of fig. 2.
Fig. 4 is a graph showing the relationship between the thickness of the insulating film and the ring stiffness value in embodiment C of the present invention.
Fig. 5 is a graph showing the relationship between the thickness of the insulating film and the scratch resistance in example C of the present invention.
Fig. 6 is a graph showing the relationship between the thickness of the insulating film and the scratch resistance in example C of the present invention.
Detailed Description
The embodiments of the present invention are described in detail below. All academic and patent documents described in the present specification are incorporated herein by reference.
(embodiment A)
(1. insulating coating Material)
An insulating coating material according to an embodiment of the present invention is characterized in that: the insulating film has an adhesive layer on at least one surface thereof, and an integrated laminate in which members are laminated in the order of insulating cover material/lead wire/insulating cover material so that the adhesive layer of the insulating cover material is in contact with the lead wire has a scratch resistance of 3.0 times or more and a thickness of 20 [ mu ] m or less.
The method for producing the laminate will be described below. The integrated laminate can be produced by laminating members in the order of metal plate/buffer material/insulating coating material/lead wire/insulating coating material/buffer material/metal plate, and heating and pressing the laminated members.
The metal plate to be used is not particularly limited, and a SUS plate may be used, and preferably the surface is subjected to polishing treatment.
The buffer material used is not particularly limited, and a polyimide film, a thick paper, or the like can be used. The heating temperature may be selected depending on the type of the material, and for example, a Jinyang plate (trade name) (manufactured by Kinyo Board, Ltd.) may be used. In addition, various cushioning materials may be used in combination. The wire used is a conductor, and is not particularly limited, and is usually a metal. Examples of the metal include copper, aluminum, and stainless steel. Copper is preferred, and aluminum is also preferred from the viewpoint of weight reduction. The metal may be any of various alloys, and various materials may be used for plating the surface of the metal, and there are no particular limitations thereon, and for example, a highly conductive Nickel coated copper (AWG: 20, CONST: 19/32) manufactured by Phlips dock may be used. The diameter of the wire is not particularly limited, and the diameter of the main wire currently used in the market is about
The heating/pressurizing conditions for producing the integrated laminate are not particularly limited, but the heating temperature is preferably in the range of 280 to 340 ℃ and the pressure is preferably 35 to 90kgf/cm2Within the range of (1), the heating is carried out within a range of 5 to 20 minutes. The heating temperature, pressure and heating/pressing time can be adjusted depending on the type of the adhesive layer used, and if the lamination and integration are performed within the above ranges, the adhesive layer melts and is adhered/fixed to the conductor, and a desired laminate can be obtained. When the insulating film has an adhesive layer on both surfaces thereof, it is preferable to insert a thin polytetrafluoroethylene sheet and heat and press the sheet so as to avoid fusion between the adhesive layer and the cushion material.
(2. method for evaluating scratch resistance of laminate and scratch resistance of insulating coating Material)
The scratch resistance of the present invention is a scratch resistance measured by using a laminate described in the section "(1. insulating coating material)" using an apparatus and a protocol described in British Standard Aerospace Series (BS EN 3475-503). For example, with respect to the laminate of fig. 1, the scratch resistance of the surface of the convex portion corresponding to the position of the wire was evaluated by using the apparatus and protocol described in british standard Aerospace Series (BS EN 3475-503). The scratch resistance was evaluated 5 times, and the average value of 5 times was used. As the measuring apparatus, for example, a repeated abrasion wear tester (REPEATED SCRAPE ABRASIONESTER; CAT158L238G1) manufactured by WELLMAN corporation can be used.
Currently, an abrasion resistance evaluation method adopted by aircraft manufacturers and electric wire/cable manufacturers is to wind an insulating coating material having a width of about 4 to 8mm around a conductor to prepare an insulated cable, and perform an abrasion resistance test thereof. Since the insulating coating material wound around the wire needs to be a strip-shaped long sample, and the conditions and methods for performing the heating/coating step while winding the strip-shaped insulating coating material around the wire have been set by manufacturers to have respective unique standards, it is difficult for manufacturers who manufacture the insulating coating material or manufacturers who manufacture the insulating film used for the insulating coating material to evaluate the abrasion resistance. That is, if the manufacturer who manufactures the insulating coating material or the manufacturer who manufactures the insulating film used in the insulating coating material is to evaluate the wear resistance, it takes much time and labor to make a sample for the evaluation. First, it is necessary to provide an adhesive layer on a long insulating film by a coating method or a lamination method, and then heat/clad the insulating film processed into a tape shape while continuously winding it on a wire using a wire covering machine described in
In contrast, the present inventors have conducted extensive studies and found a simpler method than the conventional one, which can confirm the characteristics required for the edge coating material and/or the insulating film having excellent abrasion resistance from another characteristic, and the scratch resistance measured by this method can be used to evaluate the produced laminate having the structure shown in fig. 1, and thus a film having excellent abrasion resistance can be obtained accurately and efficiently without requiring complicated steps. That is, the present inventors found a correlation between the wear resistance actually evaluated and the result of the scratch resistance when the laminate of the configuration of fig. 1 was used. The present inventors produced various known insulating films for conventional insulating coatings, including an Apical film manufactured by Kaneka corporation, a Kapton film manufactured by dupont corporation, and a film having excellent dynamic cut resistance as described in detail in
That is, the present invention includes a method for evaluating the scratch resistance of an insulating coating material, in which a wear resistance is evaluated using a laminate in which an insulating film, an adhesive layer, and a conductive wire are laminated in the following order (a) or (b);
(a) insulating film-adhesive layer-wire-adhesive layer-insulating film,
(b) Adhesive layer-insulating film-adhesive layer-wire-adhesive layer-insulating film-adhesive layer.
The method for evaluating scratch resistance is not particularly limited, and examples thereof include a method using the laminate in the evaluation method described in British Standard Aerospace Series (BS EN 3475-503), and "evaluation of scratch resistance" as used herein is synonymous with "measurement of scratch resistance", "evaluation of abrasion resistance" or "measurement of abrasion resistance". As a more specific step, the method described in the later-described embodiment may be used.
When the scratch resistance of the laminate of fig. 1 is evaluated based on the above evaluation method, it is possible to study, without complicated and time-consuming steps, what properties the insulating coating material has to have in order to make the insulated lead wire processed by coating the insulating coating material on the lead wire exhibit wear resistance, and it is possible to very easily manufacture the insulating coating material excellent in wear resistance without performing complicated and time-consuming tests of actually manufacturing an insulated cable by winding a long strip-like insulating coating material around the lead wire and heating/cladding the insulated cable and evaluating the wear resistance. As a result, the efficiency of development of the insulating coating material can be effectively improved.
The physical property value required for abrasion resistance described in British Standard aeronautics Series (BS EN 3475-503) is 100 times. This standard is an approximate wear resistance standard that aircraft manufacturers use for reference, and although the standard differs depending on the thickness of the material, most of thin insulating coating materials used in civil aircraft and the like are designed to meet the 100-time standard more in practice. However, in the present embodiment, in order to provide an insulating coating material having higher wear resistance, it is acceptable to perform the treatment up to 300 times or more.
On the other hand, the wear resistance of the insulating coating material is largely determined by the characteristics of the insulating film, and the thinner the thickness of the insulating film, the worse the wear resistance. Particularly, as for an insulating coating material using a thin insulating film of 20 μm or less, there is no insulating coating material that is excellent in that the abrasion resistance of an insulated wire can be greatly improved. According to the present invention, even when a thin insulating film of 20 μm or less is used, the abrasion resistance of the obtained insulated cable can be improved.
The insulating coating material of the present embodiment has a scratch resistance of 3.0 times or more in a laminate produced by the method of the present invention. The scratch resistance is preferably 3.5 times or more, more preferably 4.0 times or more, and particularly preferably 4.5 times or more. If the insulating film and the insulating coating material are selected so that the scratch resistance is 3.0 times or more, excellent abrasion resistance can be achieved even if the thickness of the insulating film and the thickness of the insulating coating material are small. In addition, from the viewpoint of the scratch resistance, the larger the value, the better, and the upper limit value is not particularly set, and for example, 1000 times may be mentioned.
As described above, the structure of the laminate used in this evaluation is completely different from that of a long lead obtained by winding a long tape around a lead and heating and pressing the tape, as shown in fig. 1, in both the structure and the manufacturing method.
When designing an insulating coating material, if attention is paid more to the characteristics of the insulating film, an insulating film satisfying the following requirements can be used: the scratch resistance of the integrated laminate obtained by laminating the components in the order of insulating film/adhesive layer/lead wire/adhesive layer/insulating film was measured 3.0 times or more. The adhesive layer is not particularly limited as long as it exhibits adhesiveness when integrated, and a fluororesin is preferably used as the adhesive layer for the reason of being able to impart insulation properties.
In addition, whether or not an insulating film satisfying the above characteristics is used in the insulating coating material can be confirmed in the following manner.
1) The adhesive layer is physically removed by cutting the surface of the insulating coating material, for example, to obtain an insulating film.
2) The insulating film obtained in the mode 1) was evaluated by laminating the members in the order of insulating film/adhesive layer/wire/adhesive layer/insulating film as described above to obtain an integrated laminate.
(3. insulating film)
The insulating film that can be used in the insulating coating material of the present embodiment is not particularly limited, and films made of various insulating materials can be used. Examples thereof include polyurethane resins, poly (meth) acrylic resins, polyvinyl resins, polystyrene resins, polyethylene resins, polypropylene resins, polyimide resins, polyamide resins, polyacetal resins, polycarbonate resins, polyester resins, polyphenylene ether resins, polyphenylene sulfide resins, polyether sulfone resins, polyether ether ketone resins, and the like, and 2 or more of these materials may be used alone or in combination. Among them, a polyimide film using a polyimide resin is particularly preferable in view of various characteristics such as heat resistance, electrical insulation, chemical resistance, and flame retardancy.
A polyimide film is produced using a polyamic acid as a polyimide precursor (hereinafter, the term "polyamide" in the present specification is sometimes used as a synonym for a polyimide precursor). Any known method can be used for producing the polyamic acid, and there is no particular limitation. For example, usually, the polyamic acid can be produced by dissolving substantially equimolar amounts of the acid dianhydride component and the diamine component in an organic solvent and stirring the resulting solution under controlled temperature conditions until the polymerization of the acid dianhydride component and the diamine component is completed. The concentration of the polyamic acid obtained is usually 5% by weight to 35% by weight, preferably 10% by weight to 30% by weight. When the concentration is within this range, the molecular weight and viscosity are suitable.
The method of polymerizing the acid dianhydride component and the diamine component may be any known method or a combination of known methods, and is not particularly limited. Further, a characteristic feature of the method for polymerizing polyamic acid is that the order of addition of monomers is controlled, and the physical properties of the polyimide to be obtained can be controlled by adjusting the order of addition of monomers.
In the present invention, any method of adding a monomer can be used for the polymerization of polyamic acid, and there is no particular limitation, and the following methods can be exemplified as typical polymerization methods.
1) A method of dissolving a diamine component in an organic polar solvent and reacting the diamine component with an acid dianhydride component in a substantially equimolar amount to the diamine component to effect polymerization.
2) A method of polymerizing an acid dianhydride component and a diamine component in an amount of an excessively small molar amount compared to the acid dianhydride component in an organic polar solvent to obtain a prepolymer having acid anhydride groups at both ends, and then using the diamine component so that the acid dianhydride component and the diamine component are substantially equimolar in the whole process.
3) A method of polymerizing an acid dianhydride component and a diamine component in an amount larger than the molar amount of the acid dianhydride component and the diamine component in the whole process by reacting the acid dianhydride component and the diamine component in an organic polar solvent to obtain a prepolymer having amino groups at both ends, adding the diamine component to the prepolymer, and using the diamine component so that the molar amounts of the acid dianhydride component and the diamine component are substantially equal to each other.
4) A method of dissolving and/or dispersing the acid dianhydride component in an organic polar solvent, and then adding a diamine component in an amount substantially equimolar to the acid dianhydride component to carry out polymerization.
5) A method of polymerizing a mixture of a substantially equimolar amount of an acid dianhydride component and a diamine component in an organic polar solvent. These methods may be used alone or in combination of two or more.
In the present invention, preferred polymerization methods for obtaining the polyimide resin include: the block component of the polyimide precursor is first formed, and then the remaining diamine and/or acid dianhydride is used to form the final polyimide precursor. In this case, the methods 1) to 5) are preferably partially used in combination.
Examples of the diamine component that can be used as the main component include 4, 4 '-diaminodiphenylpropane, 4' -diaminodiphenylmethane, 4 '-diaminodiphenylsulfide, 3' -diaminodiphenylsulfone, 4 '-diaminodiphenylether, 3' -diaminodiphenylether, 3, 4 '-diaminodiphenylether, 4' -diaminodiphenyldiethylsilane, 4 '-diaminodiphenylsilane, 4' -diaminodiphenylethyloxyphosphine, 4 '-diaminodiphenyl-N-methylamine, 4' -diaminodiphenyl-N-aniline, 1, 4-diaminobenzene (p-phenylenediamine)), (ii), Bis {4- (4-aminophenoxy) phenyl } sulfone, bis {4- (3-aminophenoxy) phenyl } sulfone, 4' -bis (4-aminophenoxy) biphenyl, 4' -bis (3-aminophenoxy) biphenyl, 1, 3-bis (3-aminophenoxy) benzene, 1, 3-bis (4-aminophenoxy) benzene, 1, 4-bis (4-aminophenoxy) benzene, 1, 3-bis (3-aminophenoxy) benzene, 3 ' -diaminobenzophenone, 4' -diaminobenzophenone, 2 ' -dimethyl-4, 4' -diaminobiphenyl, 2-bis (4-aminophenoxy phenyl) propane, 3 ' -dihydroxy-4, 4 '-diamino-1, 1' -biphenyl, and the like, and the above components may be used alone or in combination of two or more. In addition, any diamine component may be used as a subcomponent other than the above diamine component. Among them, examples of the diamine component particularly preferably used include 4, 4 '-diaminodiphenyl ether, 1, 3-bis (4-aminophenoxy) benzene, 3, 4' -diaminodiphenyl ether, 1, 4-diaminobenzene (p-phenylenediamine), and 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane.
Examples of the acid dianhydride component which can be preferably used include pyromellitic dianhydride, 2, 3, 6, 7-naphthalene tetracarboxylic dianhydride, 3, 3 ', 4, 4' -benzophenone tetracarboxylic dianhydride, 2 ', 3, 3 ' -biphenyl tetracarboxylic dianhydride, 3, 3 ', 4, 4' -biphenyl tetracarboxylic dianhydride, 2-bis (3, 4-dicarboxyphenyl) propane dianhydride, p-phenylene bis (trimellitic acid monoester anhydride), and 4, 4' -oxydiphthalic dianhydride, and these components may be used alone or in combination of two or more. In the present invention, it is preferable to use 1 or more acid dianhydride components of pyromellitic dianhydride, 3 ', 4, 4' -benzophenone tetracarboxylic dianhydride, and 3, 3 ', 4, 4' -biphenyl tetracarboxylic dianhydride.
The preferred solvent for synthesizing the polyamic acid may use any solvent capable of dissolving the polyamic acid, and is not particularly limited. Examples thereof include amide solvents such as N, N-dimethylformamide, N-dimethylacetamide and N-methyl-2-pyrrolidone. Among them, N-dimethylformamide and N, N-dimethylacetamide can be particularly preferably used.
In addition, a filler may be added to the polyimide film for the purpose of improving various film characteristics such as scratch resistance, thermal conductivity, electrical conductivity, corona resistance, and ring stiffness value. Any filler may be used, and preferred are, for example, silica, titania, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, mica, and the like.
As for the method for producing the polyimide film from the polyamic acid solution, various methods can be employed, without particular limitation. Examples of the method include a thermal imidization method and a chemical imidization method, and any method may be used for film formation.
In addition, the process for producing a polyimide film particularly preferred in the present invention preferably includes:
i) a step of reacting a diamine component and an acid dianhydride component in an organic solvent to obtain a polyamic acid solution;
ii) a step of casting a film-forming coating liquid containing the polyamic acid solution on a support;
iii) a step of heating the film-forming coating liquid on the support and then peeling the gel film from the support;
iv) a step of further heating the gel film to imidize the residual amic acid and drying the imidized amic acid.
In the above-mentioned step, a curing agent comprising a dehydrating agent represented by an acid anhydride such as acetic anhydride and an imidization catalyst represented by a tertiary amine such as isoquinoline, quinoline, β -methylpyridine, pyridine, diethylpyridine may be used.
In the present invention, a sample in which a wire is sandwiched by an insulating coating material as described above is prepared, and the scratch resistance is evaluated, and an insulating film in which the scratch resistance of the sample is 3.0 times or more may be selected. The scratch resistance can be adjusted to 3.0 times or more by appropriately selecting conditions, and for example, a monomer having a biphenyl skeleton structure may be selected as a polymerization component, or the gel film may be peeled off from the support and then stretched, or the heating temperature may be set higher in a step of further heating the gel film peeled off from the support to imidize the residual amic acid and dry it, or the like.
Those skilled in the art can make reasonable and repeated experiments based on the disclosure of the present specification and the technical level of the patent application at the time. For reference, for example, the following preferable method for obtaining an insulating film satisfying the above characteristics can be cited.
a) Diaminodiphenyl ether (ODA) is preferably used as the diamine component. More preferably, ODA is used in a proportion of 15 mol% or more based on the total diamine component.
b) A first step of reacting an acid dianhydride component and a diamine component in an organic polar solvent in a state in which one of them is in an excess molar amount to obtain a prepolymer having amino groups or acid dianhydride groups at both ends; in the second step, a solution containing polyamic acid is synthesized using the prepolymer obtained in the first step, the acid dianhydride component, and the diamine component so that the acid dianhydride component and the diamine component in all the steps are equimolar, thereby forming a polyimide precursor. The prepolymer synthesized in the first stage may be a prepolymer of a soft chemical structure or a prepolymer of a rigid chemical structure. Here, the "soft chemical structure" means that the soft chemical structure exhibits flexibility at high temperatures, and is paired with the "rigid chemical structure". Specifically, the definition of the prepolymer derived from the polyimide exhibiting flexibility at high temperature is: when the storage modulus of the polymer film is measured by a dynamic viscoelasticity measuring instrument (DMA), the storage modulus in the range of 300-450 ℃ is below 50 MPa.
c) Preferable examples of the acid dianhydride component for producing the rigid chemical structure prepolymer include pyromellitic dianhydride (PMDA) and 3, 3 ', 4, 4' -biphenyltetracarboxylic dianhydride (BPDA). As the diamine component, for example, p-Phenylenediamine (PDA) is preferable. The total amount of PMDA and BPDA is preferably 40 to 90 mol% of the acid dianhydride component in the entire polyimide. More preferably, a rigid chemically structured prepolymer is formed in the second stage.
d) The soft chemically structured prepolymer preferably contains ether linkages. For example, the content of the acid dianhydride component and/or diamine component containing an ether bond is 35 to 70 mol% based on 100 mol% of the total of the acid dianhydride component and diamine component used. In addition, when synthesizing a prepolymer having a softening chemical structure, it is preferable to contain 3, 3 ', 4, 4' -benzophenonetetracarboxylic dianhydride (BTDA). For example, preferably 10 to 55 mole% of the total acid dianhydride used to form the polyimide precursor is BTDA.
e) Preferably, BPDA is used as the acid dianhydride component. The proportion of BPDA used in the total acid dianhydride component is preferably 30 mol% or more, more preferably 50 mol% or more, still more preferably 70 mol% or more, and particularly preferably 90 mol% or more. BPDA can also be used in 100 mol%.
Here, the above-described methods are merely examples, and may be used alone or in combination of a plurality of methods. The method of obtaining the insulating film satisfying both of the above characteristics is not limited to the above method.
In the diamine component and the acid dianhydride component, ODA and PDA are preferably contained as the diamine component, and PMDA, BPDA and BTDA are preferably contained as the acid dianhydride component.
The polymerization method preferably comprises sequential polymerization of a first-stage step and a second-stage step. In the first stage, it is preferable to form a "soft chemical structure" segment, and at least ODA and at least BTDA are used as the diamine component forming the "soft chemical structure" segment, and 10 to 30 mol% of BTDA is contained in the acid dianhydride component of the entire polyimide. In the second stage, it is preferable to use a monomer capable of forming a "rigid chemical structure" segment, and PDA, PMDA and BPDA can be used as the monomer capable of forming a "rigid chemical structure" segment, and PDA and PMDA are particularly preferable as the main components. PDA is preferably 40 to 60 mol% of the diamine component of the entire polyimide, and PMDA is preferably 45 to 85 mol% of the acid dianhydride component of the entire polyimide. In order to improve the alkali resistance of the polyimide, BPDA is preferably contained in an amount of 15 to 25 mol% based on the acid dianhydride component of the entire polyimide.
The thickness of the insulating film is not particularly limited, and is preferably 20 μm or less, and more preferably 18 μm or less, for example, in order to reduce the weight. According to the present invention, even if the insulating film is made thin, the insulating film and the insulating coating material having excellent abrasion resistance can be provided. The lower limit is not particularly limited, and the thickness is preferably 5 μm or more, for example.
(4. adhesive layer)
The adhesive layer that can be used in the insulating coating material of the present embodiment is not particularly limited, and various adhesive layers can be used. The adhesive layer may be formed of any material as long as the insulating film can be adhered to a conductor such as a wire of an electric wire or a cable (lead wire), and a thermoplastic resin is preferably used. Among them, a fluororesin is more preferable from the viewpoint of insulation properties, chemical resistance, and the like.
As the fluororesin, two or more kinds, for example: tetrafluoroethylene polymer, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer, tetrafluoroethylene-ethylene copolymer, polychlorotrifluoroethylene, ethylene-chlorotrifluoroethylene copolymer, polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, and polyvinyl fluoride, etc. Among them, a tetrafluoroethylene polymer or a tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer is preferably used. FEP is more preferably used because it has a low melting point, can be pressure-bonded at a relatively low temperature, and is easy to reliably obtain a laminate.
The adhesive layer may be applied as a dispersion on the insulating film or may be provided using an adhesive film as the adhesive layer.
The thickness of the adhesive layer is not particularly limited as long as it has adhesiveness, and is preferably 0.5 to 13 μm.
The insulating coating material may have a two-layer structure, in which an adhesive layer is formed on at least one of the insulating films. In addition, the insulating film may have a structure in which adhesive layers are formed on both surfaces thereof, that is, the insulating coating material may have a three-layer structure. Further, a multilayer adhesive layer may be formed on one surface of the insulating film. Further, the insulating film may have a structure in which one adhesive layer is formed on one surface of the insulating film and a plurality of adhesive layers are formed on the other surface. Further, a structure in which a plurality of adhesive layers are formed on both surfaces of the insulating film may be employed. That is, the insulating coating material of the present embodiment can be produced by coating one or both surfaces of an insulating film such as a polyimide film as a primer layer with an adhesive layer containing a fluororesin, for example.
(5. production of insulating coating Material)
A method for producing the insulating coating material of the present embodiment will be described. The insulating coating material of the present embodiment is an insulating coating material having an adhesive layer on at least one surface of an insulating film, and is obtained by laminating the adhesive layers and then heating and firing the laminated layers. The method for producing the laminate of the insulating film and the adhesive layer may be any method known to those skilled in the art, and for example, the laminate is usually obtained by laminating a film-like adhesive layer on the insulating film or by applying a dispersion of an adhesive layer resin on the insulating film. For example, if the adhesive layer used in the present invention is a fluororesin, a dispersion obtained by dispersing, for example, tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer (PFA), Polytetrafluoroethylene (PTFE), or the like in water or an organic solvent can be used as the dispersion. Specifically, if the dispersion is applied, a dispersion of the fluororesin is prepared. The solid content concentration of the dispersion used herein is not particularly limited, but is preferably 10 to 70 wt% from the viewpoint of handling. Typical laminated films when laminated include films of tetrafluoroethylene-hexafluoropropylene copolymer, polytetrafluoroethylene, tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer, tetrafluoroethylene-ethylene copolymer, chlorinated polychlorotrifluoroethylene, and the like. If the dispersion liquid is used, the coating can be repeated several times until the fluororesin used in the laminate composed of polyimide and fluororesin of the present embodiment has reached an appropriate thickness.
Such dispersion or film may be added with an inorganic or organic filler by a known method. The surface of the fluororesin and the surface to be bonded to the polyimide film may be subjected to a known surface treatment such as corona discharge treatment or plasma discharge treatment.
The thus obtained insulating coating material is wound around a wire and used as an insulated lead (insulated cable).
(6. utilization of insulating coating Material)
The present invention includes an insulated cable (lead) provided with the insulating coating material. The related insulated cable can be preferably applied to wires such as an aircraft aerospace wire and a cable (lead wire).
The wire such as the electric wire and the cable (lead wire) may be a conductor, and any material may be used, and generally, a metal is used. Examples of the metal include copper, aluminum, and stainless steel. Copper is preferred, and aluminum is preferred from the viewpoint of weight reduction. The metal may be a variety of alloys, or may be plated with a variety of materials on the surface.
Various methods can be used as a method for manufacturing the insulated cable, and there is no particular limitation. For example, the insulating coating material is formed into a strip shape (long shape) and the insulating material strip is spirally (spirally) wound around a conductor (for example, metal). Further, after the insulating coating material tape is wound around the conductor once, another insulating coating material tape may be further wound in a laminated manner.
When the insulating-coated material tape is wound around a conductor, the tension applied to the tape can be widely varied within a predetermined range from a sufficient tension that can avoid the occurrence of wrinkles (crimping) to a sufficiently strong tension that stretches the tape to form a neck. Even if the tension is small, the tape shrinks due to the influence of heat (for example, heating to 240 to 500 ℃) in the heat sealing step performed after winding, and the insulating coating material can coat the conductor with good adhesion. The heat-sealing step may be appropriately set according to the thickness of the insulating film, the thickness of the adhesive layer, the material of the conductor, the speed of the production line, the length of the sealing furnace, and the like. The insulating coating material may be wound around the conductor using a standard wire coating machine (winder) or the like.
(embodiment B)
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