JP2012144701A - Adhesive tape, flat wire covered with adhesive tape, and electrical instrument using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive tape which does not require pressurization and heating when it is adhered and is free from entrapping of gas bubbles.SOLUTION: The adhesive tape is characterized in that the initial wetting speed defined below is not less than 1 cm/s. The initial wetting speed is the adhesion area per unit time (second) immediately after contact when the adhesive surface of the adhesive tape is brought into contact with a polycarbonate sheet at an ambient temperature of 23°C. The wettability, defined below, of the adhesive tape is preferably 70% or higher. The wettability is the percentage of the adhesion area after elapsing 30 seconds when the adhesive surface of a 7 cm×7 cm piece of the adhesive tape is brought into contact with a polycarbonate sheet at an ambient temperature of 23°C.

Description

  The present invention relates to an adhesive tape having high wettability to an adherend. The present invention also relates to a rectangular electric wire covered with an adhesive tape having high wettability, and an electric device using the same.

  The pressure-sensitive adhesive tape has a gel-like soft pressure-sensitive adhesive layer on a base material such as a plastic film or paper, and the pressure-sensitive adhesive layer exhibits an adhesive force when wet with respect to an adherend while being solid. In other words, the pressure-sensitive adhesive layer is required to be sufficiently wetted against the adherend, but requires a cohesive force (hardness) that resists peeling. ing.

  For this reason, in general, the pressure is applied when the adhesive tape is bonded to the adherend, and in some cases, the pressure is applied in a heated state so that the adhesive tape is sufficiently adhered to the adherend. In this way, when pressure and heating are possible during construction, it can be used even if the adhesive tape has poor wettability. If a problem occurs, such construction is difficult.

  Moreover, as a case where wettability with respect to the adherend becomes a problem, it is conceivable that air bubbles enter between the adherend and the adhesive tape. For example, when sticking a decorative film, in order to prevent bubbles from remaining, it is known to provide convex protrusions in the pressure-sensitive adhesive layer, to form concave streaks, and to release the bubbles (for example, (See Patent Document 1 and Patent Document 2).

  Moreover, in order to insulate a flat electric wire, it coat | covers and uses with an appropriate insulating material. Flat wires are used in rotating machinery used in various electrical equipment, coil equipment such as magnets, etc., and appropriately insulate wires made of copper, copper alloys, aluminum, aluminum alloys, or combinations of these metals. The one covered with the material is used. In recent years, various superconducting materials such as bismuth, yttrium, and niobium have been developed, and superconducting magnets, superconducting coils, and the like have been developed by using superconducting wires using these as flat wires. As a specific example of use, it is known that a bare rectangular electric wire is spirally wound and covered with an insulating film tape (see, for example, Patent Document 3). Further, it is known that a flat conductor is covered with a resin insulation coating material (see, for example, Patent Document 4).

  However, in the insulation method described in Patent Document 3, it is necessary to provide a wrap portion in which a part of the insulating film tape is overlapped in order to ensure insulation, but a gap is generated in the wrap portion, and the insulating film tape is bare. In some cases, bubbles were included because they were not completely adhered to the flat electric wires. In such gaps and bubbles, the electric field concentrates on the part and weak discharge is generated. This is called partial discharge, which causes deterioration of the insulator and may lead to dielectric breakdown after a long time. In particular, in the case of a rectangular electric wire used in liquid nitrogen such as a superconducting wire, it has been confirmed by the present inventor that the partial discharge start voltage is remarkably lowered due to air bubbles caught in the wrap portion.

  In addition, the insulating method described in Patent Document 4 is a method in which a rectangular electric wire is covered with a molten thermoplastic resin, and depending on the type of material, the temperature is considerably high, and there is a fear that the properties of the wire are deteriorated.

Japanese Unexamined Patent Publication No. 08-113768 JP 2006-299283 A JP 2000-4552 JP JP 2003-272916 A

  This invention is made | formed in view of the said situation, and it is providing the adhesive tape which does not require pressurization and a heating at the time of sticking, and does not involve a bubble.

  The present inventors have found that the above problems can be solved by using an adhesive tape having high wettability, and have completed the present invention.

That is, the pressure-sensitive adhesive tape of the present invention is characterized in that the initial wetting rate defined below is 1 cm ² / sec or more.
Initial wetting speed: Adhesive area per unit time (seconds) immediately after contact when the pressure-sensitive adhesive surface of a pressure-sensitive adhesive tape of 7 cm × 7 cm is brought into contact with a polycarbonate plate in a 23 ° C. atmosphere.

In particular, the pressure-sensitive adhesive tape of the present invention preferably has a wettability defined below of 70% or more.
Wettability: Ratio of the adhesion area after 30 seconds when the pressure-sensitive adhesive surface of a 7 cm × 7 cm pressure-sensitive adhesive tape is brought into contact with a polycarbonate plate in an atmosphere at 23 ° C.

  The pressure-sensitive adhesive tape of the present invention is characterized in that a pressure-sensitive adhesive layer made of a silicone-based pressure-sensitive adhesive composition is provided on a substrate. Further, the substrate is made of a polyimide resin.

  Furthermore, the adhesive tape of the present invention preferably has an adhesive force to a stainless steel plate (180 ° peel, pulling speed 300 mm / min) of 0.01 to 10 N / 20 mm.

  The pressure-sensitive adhesive tape of the present invention is suitable as a pressure-sensitive adhesive tape for covering a rectangular electric wire and insulating it, and provides a rectangular electric wire that is covered with the pressure-sensitive adhesive tape of the present invention. The flat electric wire is preferably a superconducting wire.

  Moreover, this invention provides the electric equipment using the flat electric wire coat | covered with the said adhesive tape.

  Since the pressure-sensitive adhesive tape of the present invention has high wettability, it does not require pressurization or heating at the time of bonding, and can be easily bonded without involving bubbles. In particular, by using the pressure-sensitive adhesive tape of the present invention for covering a flat electric wire, it is possible to cover the flat electric wire under room temperature conditions, to suppress the deterioration of the flat electric wire due to heat, and to wrap the adhesive tape for covering Even when spirally wound while providing the portion, the viscoelastic layer fills the gap of the wrap portion, and the covering material adheres to the electric wire so that bubbles do not enter. For this reason, there is no discharge from a wrap part or a bubble part, and a high dielectric breakdown voltage can be obtained.

FIG. 1A is a schematic view showing a method for measuring the initial wetting speed and wettability of the pressure-sensitive adhesive tape of the present invention, and FIG. 1B is an example of the analysis result. FIG. 2 is a schematic side view showing an embodiment of the pressure-sensitive adhesive tape of the present invention. FIG. 3 is a schematic perspective view showing an embodiment of a flat electric wire covered with the adhesive tape of the present invention. FIG. 4 is an explanatory diagram showing a method for evaluating a partial discharge start voltage of a flat electric wire. FIG. 5 is a schematic perspective view showing an embodiment of a coil which is an example of an electric device.

  The pressure-sensitive adhesive tape of the present invention can have a structure in which a pressure-sensitive adhesive layer is provided on one side of a substrate.

The pressure-sensitive adhesive tape of the present invention is characterized in that the initial wetting rate defined below is 1 cm ² / sec or more.
Initial wetting speed: Adhesive area per unit time (seconds) immediately after contact when the pressure-sensitive adhesive surface of a pressure-sensitive adhesive tape of 7 cm × 7 cm is brought into contact with a polycarbonate plate in a 23 ° C. atmosphere.

In the present invention, the initial wetting rate of the pressure-sensitive adhesive tape is 1 cm ² / second or more, preferably 10 cm ² / second or more, more preferably 30 cm ² / second or more, and further preferably 50 cm ² / second or more. If the initial wetting rate is 1 cm ² / sec or more, it is not necessary to pressurize or heat at the time of bonding, and can be easily bonded without involving bubbles. The upper limit of the initial wetting rate is not particularly limited, but is usually about 100 cm ² / sec in consideration of measurement accuracy and simplicity. On the other hand, if the initial wetting rate is less than 1 cm ² / sec, spots are formed on the wetting when pasting to the adherend, and bubbles are bitten. Also, in order to prevent air bubbles from getting caught, special operations are required, such as using a squeegee to gradually bond or spraying a liquid containing a surfactant or alcohol onto the adherend and extruding the air bubbles after bonding. It becomes.

When the adhesive tape of the present invention is used as an adhesive tape for covering a rectangular electric wire, if the initial wetting rate of the adhesive tape is 1 cm ² / sec or more, the rectangular electric wire can be coated at room temperature conditions, The adhesive layer fills the gap in the wrap part and the covering material adheres to the wire even when the adhesive tape for coating is spirally wound while providing the wrap part. Air bubbles can be prevented from entering. For this reason, there is no discharge from a wrap part or a bubble part, and a high dielectric breakdown voltage can be obtained.

The pressure-sensitive adhesive tape of the present invention preferably has a wettability defined below of 70% or more.
Wettability: Ratio of the adhesion area after 30 seconds when the pressure-sensitive adhesive surface of a 7 cm × 7 cm pressure-sensitive adhesive tape is brought into contact with a polycarbonate plate in an atmosphere at 23 ° C.

  When the wettability is 70% or more, preferably 80% or more, more preferably 90% or more, for example, when a conductor such as a rectangular wire is covered with insulation, a new pressurizing device is provided in the winding device. There is an advantage that there is no need and adhesion with the wire and adhesion with the back surface of the covering tape can be obtained. The upper limit of wettability may be 100%, but may be about 98%. On the other hand, if the wettability is 70% or more, it is easy to obtain sufficient adhesion to the back of the wire or the covering tape just by being wound by the winding device. , It is possible to reduce the number of cases that must be adhered.

  The initial wetting rate and wettability measuring method in the present invention will be described with reference to FIG.

  FIG. 1 is a schematic view showing the wettability measuring method of the present invention. In FIG. 1A, 1 is an adhesive tape to be measured, 4 is a polycarbonate plate as an adherend, and 5 is a digital microscope for observing the bonded surface.

  In the measurement of the initial wetting speed and wettability of the present invention, the pressure-sensitive adhesive tape to be measured is cut into a width of 7 cm and a length of 8 cm to obtain an evaluation sample. In order to fix the adhesive tape 1 to the polycarbonate plate 4, 1 cm of one end in the length direction of the adhesive layer surface of the adhesive tape 1 is bonded onto the polycarbonate plate 4. A digital microscope 5 is installed near the center of the entire length of the adhesive tape 1, and is bonded to the polycarbonate plate 4 by its own weight, and the state of the entire sample surface is recorded by the digital microscope 5. The recorded image is analyzed for changes over time in the area of adhesion to the polycarbonate plate by image analysis software (for example, “WinRoof” manufactured by Mitani Corporation). An example of the analysis result is shown in FIG. The initial wetting speed is calculated from the slope immediately after the start of adhesion, which can be read from this graph, and the wet area ratio after 30 seconds is defined as the wettability. In addition, when the width | variety of the adhesive tape to evaluate is less than 7 cm, it is also possible to carry out proportional conversion about the initial wetting speed.

  In addition, in Fig.1 (a), the measuring method about the adhesive tape which used the transparent base material for the base material is shown. That is, the state of the bonded portion is observed with the digital microscope 5 from the base material side, but when measuring an adhesive tape using an opaque base material as the base material, the digital microscope 5 is opposite to the adhesive tape 1. It is also possible to observe the state of adhesion through the polycarbonate plate 4 installed on the side.

(Base material)
In the present invention, the substrate is not particularly limited, and conventionally known materials can be used, but in order to make the wettability of the adhesive tape 70% or more, it is desirable to have a certain strength and hardness, For example, it is desirable to use a base material having a tensile modulus (ASTM D-882) of 2.0 GPa or more, preferably 2.5 GPa or more, more preferably 3.0 GPa or more (usually 10 GPa or less).

  When the adhesive tape of the present invention is used for covering a rectangular electric wire, the substrate is not particularly limited as long as it has insulating properties, radiation resistance, heat resistance, and the like. For example, polyimide resin, polyether resin, polyether ether ketone resin, Examples include polyetherimide resins and polyamideimide resins. These resins may be used alone or in combination of two or more.

  Among these resins, in the present invention, it is particularly preferable to use a polyimide resin as a base material. Polyimide resin is a non-flammable material with heat resistance, and as an insulating material used in electrical equipment, it is based on the flat wire covering material (adhesive tape for flat wire) of the present invention in that it has excellent flame resistance. It has excellent properties as a material.

  The polyimide resin can be obtained by a known or conventional method. For example, a polyimide can be obtained by reacting an organic tetracarboxylic dianhydride and a diamino compound (diamine) to synthesize a polyimide precursor (polyamic acid) and dehydrating and ring-closing the polyimide precursor.

  Examples of the organic tetracarboxylic dianhydride include pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, and 2,2-bis (2,3-dicarboxyl). Phenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3,3-hexa Fluoropropane dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) sulfone A dianhydride etc. are mentioned. One of these organic tetracarboxylic dianhydrides may be used alone, or two or more thereof may be mixed and used.

  Examples of the diamino compound include m-phenylenediamine, p-phenylenediamine, 3,4-diaminodiphenyl ether, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenyl sulfone, and 3,3′-diaminodiphenyl sulfone. 2,2-bis (4-aminophenoxyphenyl) propane, 2,2-bis (4-aminophenoxyphenyl) hexafluoropropane, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis ( 4-aminophenoxy) benzene, 2,4-diaminotoluene, 2,6-diaminotoluene, diaminodiphenylmethane, 2,2'-dimethyl-4,4'-diaminobiphenyl, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl and the like. These diamino compounds may be used alone or in combination of two or more.

  In addition, as a polyimide resin used in the present invention, pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride is used as an organic tetracarboxylic dianhydride, and a diamino compound is used. It is preferable to use p-phenylenediamine and 4,4′-diaminodiphenyl ether. As such a polyimide resin, commercially available products such as “Kapton” (manufactured by Toray DuPont) and “Upilex” (manufactured by Ube Industries) can also be used.

  The thickness of the base material used in the present invention is 5 to 200 μm, preferably 7 to 100 μm. When the thickness is within this range, there is an advantage that the wettability to the adherend is improved with appropriate bending elasticity and flexibility. On the other hand, when the thickness is 200 μm or less, it is possible to reduce the case where the flexibility of the base material is lacking, and it is possible to suppress the case where the wetting of the pressure-sensitive adhesive layer is not followed and the initial wetting speed is reduced, and 5 μm or more When it is, it can suppress that the intensity | strength of a base material runs short and the case where handling becomes difficult.

  When the adhesive tape of the present invention is used for covering a flat electric wire, the thickness of the substrate is 5 to 25 μm, preferably 7 to 15 μm. When the thickness is within this range, sufficient insulation can be ensured and the function as a flat wire can be exhibited. On the other hand, when the thickness is 25 μm or less, it is possible to suppress the tape from becoming thick. Therefore, when the rectangular wire is covered, the coil occupancy is suppressed from being reduced and the desired coil performance cannot be obtained. Further, when the thickness is 5 μm or more, it is possible to suppress the insulation of the wire from being lowered, and it is possible to reduce the case of dielectric breakdown during operation.

  In addition, the base material used in the present invention may be subjected to chemical treatment such as sputter etching treatment, corona treatment, plasma treatment, primer, etc. in order to improve anchoring force with a viscoelastic layer (adhesive layer) described later. It can also be applied.

(Adhesive layer)
In the present invention, the pressure-sensitive adhesive layer is not particularly limited as long as the initial wetting rate of the pressure-sensitive adhesive tape is 1 cm ² / sec or more, and can be appropriately selected from known base polymers. Examples thereof include acrylic polymers, rubber polymers, vinyl alkyl ether polymers, silicone polymers, polyester polymers, polyamide polymers, urethane polymers, fluorine polymers, and epoxy polymers.

In the present invention, in order for the initial wetting speed of the pressure-sensitive adhesive tape to be 1 cm ² / second or more, the pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer has a temperature of 0 to 80 as the viscoelastic body layer (pressure-sensitive adhesive layer). It is preferable to use one having a dynamic elastic modulus of 1 × 10 ³ to 1 × 10 ⁸ N / m ² in the range of 1 ° C., particularly preferably in the range of 1 × 10 ⁴ to 1 × 10 ⁶ N / m ² . belongs to. That is, when it is 1 × 10 ³ N / m ² or more, the shape as an adhesive tape can be maintained and the case of non-uniform wetting can be reduced, and conversely, if it is 1 × 10 ⁸ N / m ² or less, it is flexible. It is possible to suppress the deterioration of the wettability, and to reduce the case where the initial wetting rate is lowered and the wettability is lowered.

  In addition, the pressure-sensitive adhesive layer desirably has a glass transition temperature (Tg) of −5 ° C. or lower, preferably −10 ° C. or lower, because it is easy to balance the adhesion properties to the adherend. When the glass transition temperature is −5 ° C. or lower, it is possible to reduce the case where the polymer easily flows and wets the adherend sufficiently, and the initial wetting speed and adhesive force are reduced.

  In the present invention, the pressure-sensitive adhesive layer is preferably composed of a pressure-sensitive adhesive composition containing a silicone polymer in order to obtain a high initial wetting rate. The silicone-based pressure-sensitive adhesive composition contains a crosslinked structure of a blend mainly composed of silicone gum and silicone resin.

  In particular, even when the pressure-sensitive adhesive tape of the present invention is used for covering a flat electric wire, the base polymer constituting the pressure-sensitive adhesive layer is preferably a silicone polymer because it is excellent in heat resistance and transparency.

  As the silicone gum, various types used as a silicone-based pressure-sensitive adhesive composition can be used without particular limitation. For example, an organopolysiloxane having dimethylsiloxane as a main constituent unit can be preferably used. A vinyl group and other functional groups may be introduced into the organopolysiloxane as necessary. The weight average molecular weight of the organopolysiloxane is usually 180,000 or more, preferably 280,000 to 1,000,000, particularly 500,000 to 900,000. These silicone gums can be used alone or in combination of two or more. When the weight average molecular weight is low, the gel fraction can be adjusted by the amount of the crosslinking agent.

As a silicone resin, various things currently used as a silicone type adhesive composition can be especially used without a restriction | limiting. For example, at least one unit selected from M unit (R ₃ SiO _1/2 ), Q unit (SiO ₂ ), T unit (RSiO _3/2 ), and D unit (R ₂ SiO) (said unit) Among them, an organopolysiloxane composed of a copolymer having a monovalent hydrocarbon group or a hydroxyl group) can be preferably used. In addition to the OH group, the organopolysiloxane made of the copolymer may have various functional groups such as a vinyl group introduced as necessary. The functional group to be introduced may cause a crosslinking reaction. The copolymer is preferably an MQ resin comprising M units and Q units.

The blending ratio (weight ratio) of the silicone gum and the silicone resin is not particularly limited, but in order to make the initial wetting rate of the adhesive tape 1 cm ² / second or more, the former: the latter = 100: 0 to about 20:80, preferably Is preferably about 100: 0 to 30:70, more preferably about 90:10 to 40:60, and still more preferably about 80:20 to 50:50. The silicone gum and the silicone resin may be used simply by blending them or may be a partial condensate thereof.

  The formulation usually contains a cross-linking agent to make it a cross-linked structure. The gel fraction of the silicone pressure-sensitive adhesive layer can be adjusted by the crosslinking agent.

  In the present invention, the gel fraction of the silicone-based pressure-sensitive adhesive layer varies depending on the type of the silicone-based pressure-sensitive adhesive composition, but is generally about 20 to 99%, preferably about 50 to 98%, more preferably about 40 to 85%. Is appropriate. When the gel fraction is within the above range, there is an advantage that it is easy to balance the adhesive force and the holding force. On the other hand, when the gel fraction is 99% or less, the initial adhesive force is not too low, and the tendency of sticking to be poor can be reduced. A sufficient holding force can be obtained, and it is possible to reduce the occurrence of tape deviation and paste protrusion.

The gel fraction (% by weight) of the silicone-based pressure-sensitive adhesive layer in the present invention is obtained by taking a dry weight W ₁ (g) sample from the silicone-based pressure-sensitive adhesive layer, immersing it in toluene, and then measuring the insoluble content of the sample. It can be determined by taking out from toluene, measuring the weight W ₂ (g) after drying, and calculating (W ₂ / W ₁ ) × 100.

  The silicone-based pressure-sensitive adhesive composition of the present invention uses generally used peroxide-curing type crosslinking with a peroxide-based crosslinking agent and addition reaction-type crosslinking with a siloxane-based crosslinking agent containing a Si—H group. Can do.

  Since the crosslinking reaction of the peroxide-based crosslinking agent is a radical reaction, the crosslinking reaction usually proceeds at a high temperature of 150 ° C. to 220 ° C. On the other hand, since the crosslinking reaction between the vinyl group-containing organopolysiloxane and the siloxane-based crosslinking agent is an addition reaction, the reaction usually proceeds at a low temperature of 80 ° C. to 150 ° C. In the present invention, addition reaction type crosslinking is preferable because crosslinking can be completed in a short time at a low temperature.

  As the peroxide cross-linking agent, various types conventionally used in silicone-based pressure-sensitive adhesive compositions can be used without particular limitation. For example, benzoyl peroxide, t-butylperoxybenzoate, dicumyl peroxide, t-butylcumyl peroxide, t-butyl oxide, 2,5-dimethyl-2,5-di-t-butylperoxyhexane, 2 , 4-dichloro-benzoyl peroxide, di-t-butylperoxy-diisopropylbenzene, 1,1-bis (t-butylperoxy) -3,3,5-trimethyl-cyclohexane, 2,5-dimethyl-2 , 5-di-t-butylperoxyhexyne-3 and the like. The usage-amount of a peroxide type crosslinking agent is about 0.15-2 weight part normally with respect to 100 weight part of silicone gums, Preferably it is 0.5-1.4 weight part.

  As the siloxane-based crosslinking agent, for example, polyorganohydrodienesiloxane having an average of at least two hydrogen atoms bonded to silicon atoms in the molecule is used. Examples of the organic group bonded to the silicon atom include an alkyl group, a phenyl group, and a halogenated alkyl group, and a methyl group is preferable because it is easy to synthesize and handle. The siloxane skeleton structure may be linear, branched or cyclic, but linear is often used.

  The amount of the siloxane crosslinking agent used is usually such that 1 to 30 hydrogen atoms bonded to silicon atoms, preferably 4 to 17 are bonded to one vinyl group in the silicone gum and silicone resin. To do. When the number of hydrogen atoms bonded to the silicon atom is one or more, sufficient cohesive force can be obtained, and when the number exceeds 30, the tendency of the adhesive properties to decrease can be reduced. When a siloxane-based crosslinking agent is used, a platinum catalyst is usually used, but various other catalysts can be used. When a siloxane-based crosslinking agent is used, organopolysiloxane having a vinyl group is used as the silicone gum, and the vinyl group is preferably about 0.0001 to 0.01 mol / 100 g.

  In the pressure-sensitive adhesive layer of the present invention, in addition to the base polymer, a tackifier, a plasticizer, a dispersant, an anti-aging agent, an antioxidant, a processing aid, and a stabilizer are added as long as the effects of the present invention are not impaired. Various conventionally known additives such as antifoaming agents, flame retardants, thickeners, pigments, softeners, and fillers can be appropriately blended.

  In the present invention, the thickness of the pressure-sensitive adhesive layer is 1 to 200 μm, preferably 2 to 100 μm. When the thickness is within this range, there is an advantage that the wettability to the adherend is improved with appropriate bending elasticity and flexibility. On the other hand, when the thickness is 200 μm or less, the case where the flexibility of the pressure-sensitive adhesive layer is lost can be reduced, and it is possible to reduce the case where the initial wetting speed is reduced by preventing the pressure-sensitive adhesive layer from following the wetting. When it is, the case where adhesive force falls remarkably can be reduced.

  Particularly when the pressure-sensitive adhesive tape of the present invention is used as a pressure-sensitive adhesive tape for covering rectangular electric wires, the thickness of the pressure-sensitive adhesive layer is 1 to 25 μm, preferably 2 to 10 μm. There exists an advantage that moderate adhesiveness is acquired as the thickness of an adhesive layer is in this range. On the other hand, if the thickness of the pressure-sensitive adhesive layer is 25 μm or less, the adhesive tape is prevented from becoming thicker, so that the coil occupancy rate is suppressed from being reduced when the flat wire is covered, and the desired coil performance is obtained. The case where it cannot be reduced can be reduced, and when it is 1 μm or more, adhesion to the wire can be obtained, and the case where a defect such as a gap is formed at the interface with the wire can be reduced.

(Adhesive tape)
Next, the adhesive tape of this invention is demonstrated with reference to FIG.

  FIG. 2 is a schematic side view showing an embodiment of the pressure-sensitive adhesive tape of the present invention. In FIG. 2, the pressure-sensitive adhesive tape 1 has a configuration in which a pressure-sensitive adhesive layer 12 is provided on one side of a base material 11. The adhesive tape 1 is wound around the core material 13 in a roll shape.

  In addition, in FIG. 2, although the adhesive tape which provided the adhesive layer 12 on the single side | surface of the base material 11 is illustrated, in this invention, it is a double-sided adhesive tape which provided the adhesive layer 12 on both surfaces of the base material 11. It may be a so-called base material-less pressure-sensitive adhesive tape having only the pressure-sensitive adhesive layer 12 and having no base material. Furthermore, a release liner that protects the adhesive surface may be provided on the surface of the adhesive layer 12.

  Moreover, in this invention, conventionally well-known shapes, such as a sheet form and a film form, are included in a pressure sensitive adhesive tape.

  The production method of the pressure-sensitive adhesive tape 1 of the present invention is not particularly limited. For example, the silicone pressure-sensitive adhesive layer is formed on the substrate 11 as the viscoelastic layer 12 by a method of coating the above-described silicone pressure-sensitive adhesive composition on the substrate. Can be formed.

  More specifically, a solution obtained by dissolving a silicone-based pressure-sensitive adhesive composition containing a silicone gum, a silicone resin, a crosslinking agent, a catalyst, etc. in a solvent such as toluene is applied to the substrate, and then the formulation is heated. Evaporate the solvent and crosslink. Examples of the method for forming the silicone-based pressure-sensitive adhesive layer in the present invention include a roll coat, a kiss roll coat, a gravure coat, a reverse coat, a roll brush, a spray coat, a dip roll coat, a bar coat, a knife coat, an air knife coat, and a curtain. Examples thereof include an extrusion coating method using a coat, a lip coat, a die coater and the like.

  Moreover, the method of forming the silicone type adhesive layer which consists of a silicone type adhesive composition on a release liner, and transferring this to a base material may be used. Examples of the release liner include paper, synthetic resin films such as polyethylene, polypropylene, and polyethylene terephthalate, rubber sheets, cloths, nonwoven fabrics, nets, foam sheets, metal foils, and laminates thereof.

  The heating temperature is not particularly limited as long as the solvent can be distilled off and the predetermined crosslinking reaction proceeds. For example, when forming a silicone pressure-sensitive adhesive layer that performs addition reaction type crosslinking using toluene as the solvent, the heating temperature is 80 ° C. to 150 ° C., preferably 100 to 130 ° C.

  When the adhesive tape of the present invention is used for covering a rectangular electric wire, the thickness (total thickness) is preferably 0.007 to 0.04 mm, more preferably 0.01 to 0.03 mm, and still more preferably. Is 0.01 to 0.02 mm. When the thickness of the adhesive tape is 0.007 mm or more, the strength is sufficient and the case where the handleability is poor can be reduced. When the thickness is 0.04 mm or less, a rectangular electric wire covered with the adhesive tape is wound as an insulating coil. When it is turned, it is not preferable because it suppresses a decrease in the density of the wire and reduces the case of causing a decrease in performance.

  Moreover, the general size of a rectangular electric wire is commercially available with a thickness of 1 to 10 mm and a width of 1 to 20 mm. A general insulation coating method has a winding angle in the range of 20 ° to 80 °. In many cases, a part of the insulating coating material (insulating adhesive tape) is spirally wound with a half wrap. Therefore, considering the wire width and the winding angle, the tape width is preferably at least one time of the wire width and at most about twice the wire width. Specifically, the covering material for flat electric wires (adhesive tape for flat electric wires) of the present invention preferably has a width of 1 to 80 mm, more preferably 1.5 to 60 mm, and still more preferably 2 ~ 40 mm.

  Further, it is desirable that the covering material (adhesive tape) for covering the flat electric wire does not provide a joint when covering the flat electric wire. Therefore, when the adhesive tape of the present invention is used as an adhesive tape for covering a rectangular electric wire, it is preferably a long tape, and the length is preferably 500 m or more, preferably 1000 m or more, and more preferably 3000 m or more. Therefore, the covering material for flat electric wires (adhesive tape for flat electric wires) 1 of the present invention is wound around a winding core 13 in a roll shape, and is a so-called bobbin winding that is wound around a single winding core in a plurality of rows. It doesn't matter.

  The adhesive tape of the present invention has an adhesive strength (180 ° peel, pulling speed 300 mm / min) to the SUS304 steel plate of 0.01 to 10 N / 20 mm, preferably 0.01 to 6.0 N / 20 mm, more preferably 0.02. It is desirable to be -4.0N / 20mm, more preferably 0.1-2.0N / 20mm. If the adhesive strength is within the above range, for example, when the adhesive tape is used as an adhesive tape for covering a rectangular electric wire, the rectangular electric wire can be sufficiently intimately adhered at room temperature to easily insulate the rectangular electric wire. There is an advantage that a high breakdown voltage can be obtained. On the other hand, when the adhesive strength is 10 N / 20 mm or less, not only can it be difficult to unwind, but the tape is stretched when it is spirally wound, and warping, twisting, and the like occur in the flat rectangular wire after coating. Fear can be reduced. Further, when the adhesive force is 0.01 N / 20 mm or less, a sufficient adhesive force with respect to the rectangular electric wire can be obtained, and the possibility that gaps and bubbles are mixed can be reduced.

  The adhesive strength of the pressure-sensitive adhesive tape of the present invention is preferably in the above range, but this can be achieved by appropriately adjusting the composition of the pressure-sensitive adhesive layer. For example, when the silicone-based pressure-sensitive adhesive composition is used as the pressure-sensitive adhesive layer, the adhesive strength can be adjusted by adjusting the blending ratio of the silicone gum and the silicone resin. Specifically, the blending amount of the silicone resin can be adjusted. The adhesive force can be increased by increasing the number. More specifically, in order to set the adhesive strength of the adhesive tape to the SUS304 steel plate (180 ° peel, pulling speed 300 mm / min) to 0.01 to 10 N / 20 mm, the blending ratio (weight ratio) of silicone gum and silicone resin ) May be about the former: the latter = 100: 0 to 30:70.

  The low-speed rewinding force (pulling speed 300 m / min) of the pressure-sensitive adhesive tape of the present invention is 0.05 to 10 N / 20 mm, preferably 0.07 to 7.0 N / 20 mm, more preferably 0.1 to 5.0 N. / 20 mm, more preferably 0.2 to 3.0 N / 20 mm. If the adhesive strength of the adhesive tape is within the above range, for example, when the adhesive tape is used as an adhesive tape for covering a rectangular electric wire, the unwinding of the covering material for the rectangular electric wire (adhesive tape for the rectangular electric wire) from the wound body is not possible. There is an advantage that it is performed smoothly. On the other hand, when the rewinding force is 5 N / 20 mm or less, the case where the rewinding becomes irregular can be reduced.

(Square wire covered with adhesive tape)
The present invention provides a flat electric wire covered with the above-mentioned adhesive tape for covering a flat electric wire. The flat electric wire used in the present invention is not particularly limited, and a conventionally known product can be used. As the material, a wire made of copper, copper alloy, aluminum, aluminum alloy, or a combination of these metals can be used. . Also, rectangular electric wires made of various superconducting materials such as bismuth, yttrium, and niobium can be used.

  The method for coating the flat electric wire is not particularly limited, and may be a conventionally known method of winding the adhesive tape for coating in a spiral shape, or covering the flat electric wire while attaching the flat electric wire in the length direction of the covering adhesive tape. It may be a method (with vertical).

  Moreover, it is desirable to use a flat electric wire having a width / thickness ratio (aspect ratio) of about 1 to 60 in the sectional shape of the flat electric wire used in the present invention.

(Electrical equipment)
The flat electric wire covered with the covering material for flat electric wires (adhesive tape) of the present invention can be used for electric devices such as an insulating coil, a superconducting coil, and a superconducting magnet. In particular, a flat electric wire covered with a covering material for a flat electric wire according to the present invention has no air bubbles or gaps between the covering material and the wire, and has a high dielectric breakdown voltage. It has the advantage that it can be designed with high power and can provide a device with high output.

  Note that a coil 200 such as an insulating coil or a superconducting coil, which is an example of an electric device, includes a winding frame 210 and a rectangular electric wire covered with an adhesive tape wound around the winding frame 210 as shown in FIG. 100.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.

Example 1
70 parts by weight of “X-40-3229” (silicone gum, solid content 60%, manufactured by Shin-Etsu Chemical Co., Ltd.) and “KR-3700” (silicone resin, solid content 60%, manufactured by Shin-Etsu Chemical Co., Ltd.) ) 30 parts by weight, "PL-50T" (made by Shin-Etsu Chemical Co., Ltd.) 0.5 parts by weight as a platinum catalyst, 315 parts by weight of toluene as a solvent, and stirred with a disper to prepare a silicone-based pressure-sensitive adhesive composition . A substrate made of polyimide resin “Kapton 40EN” (thickness 10.0 μm, tensile elastic modulus 5.8 GPa, manufactured by Toray DuPont) was applied with a fountain roll so that the thickness after drying was 3 μm, and the drying temperature was 150 ° C., The pressure-sensitive adhesive tape was prepared by curing and drying under the condition of a drying time of 1 minute to form a silicone pressure-sensitive adhesive layer having a gel fraction of 74% on the polyimide resin substrate. This was wound around a winding core (inner diameter 76 mm) to obtain a roll-shaped wound body.

(Example 2)
An adhesive tape was produced in the same manner as in Example 1 except that “Kapton 50H” (thickness 12.5 μm, tensile elastic modulus 3.50 GPa, manufactured by Toray DuPont) was used as a base material made of polyimide resin.

(Example 3)
60 parts by weight of “X-40-3229” (silicone gum, solid content 60%, manufactured by Shin-Etsu Chemical Co., Ltd.) and “KR-3700” (silicone resin, solid content 60%, Shin-Etsu Chemical Co., Ltd.) as silicone-based viscoelastic bodies (Manufactured) A rectangular wire covering material in which a silicone pressure-sensitive adhesive layer having a gel fraction of 80% was formed on a polyimide resin substrate in the same manner as in Example 1 except that the amount was 40 parts by weight. This was wound around a winding core (inner diameter 76 mm) to obtain a roll-shaped wound body.

Example 4
50 parts by weight of “X-40-3229” (silicone gum, solid content 60%, manufactured by Shin-Etsu Chemical Co., Ltd.) and “KR-3700” (silicone resin, solid content 60%, Shin-Etsu Chemical Co., Ltd.) as silicone-based viscoelastic bodies (Manufactured) A rectangular wire coating material was produced in the same manner as in Example 1 except that the amount was 50 parts by weight, and a silicone pressure-sensitive adhesive layer having a gel fraction of 65% was formed on a polyimide resin substrate. This was wound around a winding core (inner diameter 76 mm) to obtain a roll-shaped wound body.

(Comparative Example 1)
100 parts by weight of “KR-3700” (silicone resin, solid content 60%, manufactured by Shin-Etsu Chemical Co., Ltd.) as a silicone-based adhesive, 0.5 part by weight of “PL-50T” (manufactured by Shin-Etsu Chemical Co., Ltd.) as a platinum catalyst, 315 parts by weight of toluene as a solvent was blended and stirred with a disper to prepare a silicone-based pressure-sensitive adhesive composition. A substrate made of polyimide resin “Kapton 40EN” (thickness 10.0 μm, tensile elastic modulus 5.8 GPa, manufactured by Toray DuPont) was applied with a fountain roll so that the thickness after drying was 3 μm, and the drying temperature was 150 ° C., The pressure-sensitive adhesive tape was cured and dried under the condition of a drying time of 1 minute to form a silicone pressure-sensitive adhesive layer having a gel fraction of 38% on the polyimide resin substrate. This was wound around a winding core (inner diameter 76 mm) to obtain a roll-shaped wound body.
(Comparative Example 2)
Kapton 50H (thickness 12.5 μm, manufactured by Toray DuPont) was used as a base material, and was used as it was without an adhesive layer.

(Evaluation)
About an Example and a comparative example, initial stage wetting speed, wettability, adhesive force, and partial discharge start voltage were measured, respectively. The results are shown in Table 1.

(Measurement of initial wetting speed and wettability)
About the adhesive tape created by each Example and the comparative example, it cut | disconnected in width 7cm and length 8cm, and was set as the sample for evaluation. At 23 ° C. and 50% RH atmosphere, 1 cm of one end of the adhesive surface of the sample for evaluation is attached and fixed to a polycarbonate plate (Takiron product number 1600), and the sample for evaluation using the apparatus shown in FIG. A digital microscope recorded the state when the glass was bonded to the polycarbonate plate under its own weight. The recorded image was analyzed with the image analysis software ("WinRoof" manufactured by Mitani Shoji Co., Ltd.) to analyze the change over time of the adhesion area to the polycarbonate plate. The initial wetting speed was calculated from the slope immediately after the start of adhesion, and the wetting area after 30 seconds. The ratio was defined as wettability.

(Measurement of adhesive strength)
The pressure-sensitive adhesive tapes produced in each of the examples and comparative examples were cut into a width of 20 mm and a length of 150 mm to obtain evaluation samples. In a 23 ° C., 50% RH atmosphere, the adhesive surface of the sample for evaluation was attached to a SUS304 steel plate by a reciprocating 2 kg roller. After curing at 23 ° C. for 30 minutes, a peel test was performed using a universal tensile tester “TCM-1kNB” manufactured by Minebea Co., Ltd. at a peel angle of 180 ° and a pulling speed of 300 mm / min to measure the adhesive force.

(Measurement of partial discharge start voltage)
About the adhesive tape produced in each Example and the comparative example, and the base material of the comparative example 2, it was set as the test piece of width 5mm, and "Di-BSCCO" (wire material: bismuth system superconducting wire, thickness 0.23mm x width 4 as a flat electric wire) 3 mm (manufactured by Sumitomo Electric Industries, Ltd.), as shown in FIG. 3, an evaluation sample 2 having a winding angle of 60 ° and a length of 10 cm in which the overlap of the covering materials was spirally covered with about 2.0 mm was prepared. . In FIG. 3, reference numeral 21 denotes a flat electric wire, 22 denotes a test piece (a covering material or base material for a flat electric wire), and 23 denotes a lap portion of the test piece 22.

  The partial discharge starting voltage in liquid nitrogen was measured by the apparatus shown in FIG. In FIG. 4, 31 is a container, 32 is an electrode, and 33 is a support for holding the evaluation sample 2 and the electrode 32. In the container 31, the evaluation sample 2 was disposed so as to be sandwiched between the electrode 32 and the support 33. A partial discharge measuring device 34 is connected to the upper electrode 32, and a ground 35 is connected to the flat electric wire of the evaluation sample 2. Liquid nitrogen was added so that at least the evaluation sample 2 was immersed, and the measurement was started with the temperature stabilized (after about 15 minutes). The electrode size is 25 mmφ, R2.5 mm, and the contact area is 20 mmφ. When boosting is performed at a boosting rate of 200 Vrms / second, a discharge with a discharge charge of 100 pC or more is confirmed to be 50 PPS (number of discharge charges generated per unit time) or more. The applied voltage at that time was defined as the partial discharge start voltage.

The adhesive tape having an initial wetting speed of 1 cm ² / sec as in the examples has high wettability to the adherend, and when this is used as an adhesive tape for covering a rectangular electric wire, the partial discharge start voltage is an adhesive. It was confirmed that the value was more than twice as high as the case where only the base material was coated without providing a layer.
Further, as in Comparative Example 1, even if the pressure-sensitive adhesive tape has high adhesiveness to the adherend, if it is inferior in initial wettability, it will bite bubbles, so when this is used as a pressure-sensitive adhesive tape for covering rectangular wires, It can be seen that the partial discharge start voltage is inferior to that of the example.

DESCRIPTION OF SYMBOLS 1 Adhesive tape 11 Base material 12 Adhesive layer 13 Core 2 Evaluation sample 21 Flat electric wire 22 Test piece 23 Wrap part 31 Container 32 Electrode 33 Support | pillar 34 Partial discharge measuring device 35 Ground 4 Polycarbonate board 5 Digital microscope 100 Cover for flat electric wire Flat wire 200 coated with material 210 Coil 210 Reel

Claims (9)

An adhesive tape having an initial wetting rate defined below as 1 cm ² / sec or more.
Initial wetting speed: Adhesive area per unit time (seconds) immediately after contact when the pressure-sensitive adhesive surface of a pressure-sensitive adhesive tape of 7 cm × 7 cm is brought into contact with a polycarbonate plate in a 23 ° C. atmosphere. The adhesive tape according to claim 1, wherein the wettability defined below is 70% or more.
Wettability: Ratio of the adhesion area after 30 seconds when the pressure-sensitive adhesive surface of a 7 cm × 7 cm pressure-sensitive adhesive tape is brought into contact with a polycarbonate plate in an atmosphere at 23 ° C. The pressure-sensitive adhesive tape according to claim 1, wherein a pressure-sensitive adhesive layer made of a silicone-based pressure-sensitive adhesive composition is provided on a substrate. The pressure-sensitive adhesive tape according to claim 3, wherein the substrate is made of a polyimide resin. The pressure-sensitive adhesive tape according to any one of claims 1 to 4, wherein the adhesive strength to a SUS304 steel plate (180 ° peel, pulling speed 300 mm / min) is 0.01 to 10 N / 20 mm. The pressure-sensitive adhesive tape according to any one of claims 1 to 5, wherein the pressure-sensitive adhesive tape is used for covering a flat electric wire and covering and insulating the flat electric wire. A flat electric wire covered with an adhesive tape, which is covered with the adhesive tape according to any one of claims 1 to 5. The flat electric wire covered with the adhesive tape according to claim 7, wherein the flat electric wire is a superconducting wire. An electric device using a flat electric wire covered with the adhesive tape according to claim 7 or 8.

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