JP2016121285A - Insulation paper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulation paper excellent in heat resistance for a long time and easy to manufacture.SOLUTION: There is provided an insulation paper used for at least one of a motor and an inverter where at least two sheets are laminated by an additive, the additive is a thermosetting additive containing a polyurethane resin (A) and an epoxy resin (B), the polyurethane resin (A) has a carboxyl group, and acid value of the polyurethane resin (A) is 5 to 30 mgKOH/g. There is the insulation paper containing a phenoxy resin having epoxy equivalence of 5000 g/eq. or more as the epoxy resin (B) and three or more functional polyfunctional epoxy resin with the epoxy resin (B) of 20 to 100 pts.mass based on 100 pts.mass of the polyurethane resin (A).SELECTED DRAWING: Figure 1

Description

  The present invention relates to insulating paper.

Conventionally, a sheet material excellent in insulation has been used as insulating paper in motors, inverters, and the like.
It is difficult to expect that sheet materials used for insulating paper are free from defects such as foreign matter and pinholes.
Therefore, conventionally, a laminated sheet in which a plurality of sheet materials are bonded with an adhesive is used as insulating paper, and even if a defective portion exists in one sheet material, this is covered with a healthy portion in the other sheet material. Ensuring insulation reliability as a whole insulation paper is widely performed.
The laminated sheet is also used as insulating paper for the purpose of giving different functions to one side and the other side of the insulating paper, or both surfaces of the insulating paper and the inside thereof.
Since the insulating paper is usually used at a location close to a source of Joule heat, it is required to have excellent heat resistance.
Therefore, a thermosetting type adhesive is widely used instead of a thermoplastic resin-based one so that the adhesive strength is not greatly reduced when heat is applied.
As this thermosetting type adhesive, polyurethane adhesives are often used because of adhesion stability at low temperatures, adhesion at room temperature, flexibility, processability, and ease of molecular design. It has been broken. As the polyurethane-based adhesive, polyester polyol, acrylic polyol as a main agent, polyisocyanate as a cross-linking agent to generate a urethane bond by these reactions, polyurethane having a certain chain length as a main agent, There are those obtained by curing the main agent with an isocyanate crosslinking agent.

  In addition, an adhesive containing a polyurethane-urea resin in which many urea bonds are introduced in the system instead of a urethane bond is used instead of the polyurethane resin, and an epoxy resin is further contained (for example, Patent Document 1). )

Japanese Patent No. 4806944

  These adhesives form an adhesive layer on one base material, and after bonding one base material and another base material with an adhesive layer, the adhesive layer is cured by heat to form a crosslinked structure. It is a type of adhesive that bonds substrates together by forming a body.

  By the way, this type of adhesive is desired to have excellent adhesion between substrates immediately after the lamination of the substrates, and after the curing of the adhesive layer, heat resistance and adhesion are improved. It is desirable to be excellent.

The adhesive of Patent Document 1 containing a polyurethane-urea resin has an advantage that the polyurethane-urea resin is excellent in heat resistance by being crosslinked with an epoxy resin.
However, since the adhesive of Cited Document 1 uses a polyurethane-urea resin, the adhesive layer becomes hard and the processability tends to be poor. Therefore, compared with the case where a polyurethane resin is used, the initial adhesive with various materials such as a film is used. It tends to be inferior in adhesion. As a result, there is a problem that it is difficult to manufacture insulating paper.
Furthermore, in the adhesive sheet of the cited document 1, the heat resistance is judged by a heat resistance test in a short time such as being left in an oven at 280 ° C. for 90 seconds and immersed in a solder bath at 260 ° C. for 1 minute. Long-term heat resistance has not been sufficiently studied so far.
As described above, since insulating paper is heated for a long period of time, long-term heat resistance is required during its useful life.
However, since the long-term heat resistance of the adhesive has not been sufficiently studied as described above, there is still room for improvement in the long-term heat resistance of the insulating paper.

  The present invention has been made in view of such problems of the prior art, and an object of the present invention is to provide an insulating paper that has excellent heat resistance for a long time and is easy to manufacture.

In the present invention, at least two sheet materials are bonded with an adhesive,
The adhesive is a thermosetting adhesive containing a polyurethane resin (A) and an epoxy resin (B),
The polyurethane resin (A) has a carboxyl group,
It is an insulating paper in which the acid value of the polyurethane resin (A) is 5 to 30 mgKOH / g.

  In the insulating paper according to the present invention, preferably, the epoxy resin (B) has an epoxy equivalent of 5,000 g / eq. The phenoxy resin which is the above and the polyfunctional epoxy resin more than trifunctional are contained.

  Furthermore, in the insulating paper which concerns on this invention, Preferably, content of the said epoxy resin (B) is 20-100 mass parts with respect to 100 mass parts of said polyurethane resins (A).

  Moreover, in the insulating paper which concerns on this invention, Preferably, the weight average molecular weights of the said polyurethane resin (A) are 1,000-500,000.

Furthermore, the insulating paper according to the present invention preferably further contains an isocyanate-based crosslinking agent,
Content of the said isocyanate type crosslinking agent is 2-10 mass parts with respect to 100 mass parts of total amounts of the said polyurethane resin (A) and an epoxy resin (B).

In the insulating paper according to the present invention, preferably, the sheet material includes a first sheet constituting a surface layer and a second sheet bonded to the first sheet via the adhesive. ,
The first sheet is a paper sheet;
The second sheet is a polyester resin sheet containing a polyester resin.

Furthermore, in the insulating paper having the first sheet and the second sheet, it is preferable that the sheet material further includes a third sheet constituting a surface layer opposite to the surface layer constituting the first sheet. Have
The second sheet constitutes an intermediate layer between the third sheet and the first sheet,
The third sheet is a paper sheet and is bonded to the second sheet by the adhesive.

  In the insulating paper according to the present invention, preferably, the polyester resin sheet contains at least one of a polyethylene terephthalate resin, a polyethylene naphthalate resin, and a polybutylene terephthalate resin.

  In the insulating paper in which the polyester resin sheet contains a polyethylene terephthalate resin, the polyester resin sheet is preferably a low oligomer type polyethylene terephthalate resin sheet.

  Furthermore, in the insulating paper according to the present invention, preferably, the paper-like sheet is formed of an aromatic polyamide fiber.

  ADVANTAGE OF THE INVENTION According to this invention, the insulating paper which is excellent in heat resistance for a long time and is easy to manufacture can be provided.

1 is a schematic cross-sectional view of insulating paper according to one embodiment. The result of the oil resistance test of the insulating paper and insulating sheet of an Example and a comparative example. The result of the wet heat test of the insulating paper of an Example and a comparative example. The result of the thermal cycle test of the insulating paper of an Example and a comparative example. The result of the heat-resistant life test of the insulating paper of an Example and a comparative example. The weight loss rate by heating of the cured product of the adhesive of the test example. The figure which shows the relationship between the thickness of the insulating paper about Examples 5-7 in which the adhesive agent of the reference example 2 was used, and a comparative tracking index (CTI). The figure which shows the relationship between the thickness of the insulating paper about Comparative Examples 8 and 9 in which the adhesive agent containing a polyester-type polyurethane resin was used, and a comparative tracking index (CTI). The figure which shows the relationship between the thickness of the insulating paper about Comparative Examples 10 and 11 using a commercially available adhesive agent, and a comparative tracking index (CTI).

  Embodiments of the present invention will be described below, but the present invention is not limited to the following embodiments.

The insulating paper of this embodiment is insulating paper used for at least one of a motor and an inverter.
In this specification, the term “insulating paper” is not intended to be “paper” in a narrow sense but is used in a broad sense including what is called “nonwoven fabric”.
In addition, the insulating paper of this embodiment is formed by adhering at least two sheet materials with an adhesive.
The adhesive is a thermosetting adhesive containing a polyurethane resin (A) and an epoxy resin (B).
The “polyurethane resin” in the present specification does not mean a “polyurethane resin” in a broad sense including “polyurethane-urea resin”, but means a “polyurethane resin” substantially not containing a urea bond.

The insulating paper of this embodiment has the 1st sheet | seat which comprises a surface layer as a said sheet material, and the 2nd sheet | seat bonded together via the said adhesive agent to this 1st sheet | seat. The first sheet is a paper sheet. The second sheet is a polyester resin sheet containing a polyester resin.
The term “paper-like sheet” in the present specification does not intend “paper” in a narrow sense but is used in a broad sense including what is called “nonwoven fabric”.

  First, the material of the adhesive will be described.

(Polyurethane resin (A))
The polyurethane resin (A) is obtained by urethane-bonding a reaction component containing a polyol component (a) having two or more hydroxyl groups per molecule and a polyisocyanate component (b) having two or more isocyanate groups per molecule. It is obtained.

The polyurethane resin (A) has an acid value of 5 to 30 mgKOH / g, preferably 9 to 25 mgKOH / g.
If the acid value of the polyurethane resin (A) is too small, the adhesive has a low crosslink density after the reaction between the polyurethane resin (A) and the epoxy resin (B), and the cured product has long-term heat resistance. It is difficult to become an excellent one. On the other hand, when the acid value is too large, the adhesive has an excessively high crosslinking density and is likely to generate strain, and is difficult to be excellent in flexibility.
In addition, the acid value of a polyurethane resin (A) means what measured the polyurethane resin (A) according to the method of JIS K1557-5: 2007 after making it a solution with methyl ethyl ketone (MEK) etc.

  The polyurethane resin (A) has a carboxyl group. The carboxyl group can be provided in the polyurethane resin by the polyol component (a) or the polyisocyanate component (b).

In the adhesive, since the polyurethane resin (A) has a carboxyl group, the carboxyl group and the epoxy group of the epoxy resin (B) can be reacted, and the polyurethane resin (A) and the epoxy resin (B). Can be subjected to a crosslinking reaction. As a result, the cured product of the adhesive has excellent heat resistance for a long time.
In Cited Document 1, from the viewpoint of improving heat resistance (solder reflow resistance, etc.), the adhesive contains an inorganic filler (silica, etc.) and a metal filler (aluminum, etc.). Even if an agent does not contain an inorganic filler and a metal filler, it can fully exhibit heat resistance by carrying out the crosslinking reaction of a polyurethane resin (A) and an epoxy resin (B). In addition, when the adhesive contains a large amount of an inorganic filler or a metal filler, the initial adhesion strength can be reduced, but the adhesive has sufficient heat resistance even if it does not contain an inorganic filler or a metal filler. Therefore, both the initial adhesion strength and the heat resistance are excellent.

  The said carboxyl group can be equipped with a polyurethane resin (A) by making the polyol component (a) contain the hydroxyl-containing compound (a1) which has a carboxyl group, for example. In this case, the polyol component (a) preferably contains a general polyol (a2) together with the hydroxyl group-containing compound (a1) having a carboxyl group.

The hydroxyl group-containing compound (a1) having a carboxyl group has two or more hydroxyl groups per molecule.
In addition, since the hydroxyl group-containing compound (a1) having a carboxyl group has two or more hydroxyl groups per molecule, it reacts with a polyisocyanate component (b) having two or more isocyanate groups per molecule to obtain a polyurethane resin. It is done.

Examples of the hydroxyl group-containing compound (a1) having a carboxyl group include dimethylolpropanoic acid, dimethylolbutanoic acid, alkylene oxide low molar adducts thereof (number average molecular weight less than 500) and γ-caprolactone low molar adducts (number average molecular weight). Less than 500), half esters derived from acid anhydrides and glycerin, compounds derived from free radical reactions of monomers containing hydroxyl groups and unsaturated groups and monomers containing carboxyl groups and unsaturated groups, etc. It is done. These compounds can be used individually by 1 type or in combination of 2 or more types. In addition, the number average molecular weight in this specification means the value measured by the terminal functional group determination method.
In addition, the above is an illustration of the preferable compound used in this invention, Comprising: This invention is not limited to these illustrated compounds. Accordingly, not only the above-described exemplary compounds, but also any other hydroxyl group-containing compound (a1) having a carboxyl group that is currently commercially available and can be easily obtained from the market can be used in the present invention.
Among these compounds, dimethylolpropanoic acid and dimethylolbutanoic acid are preferable, and dimethylolpropanoic acid is particularly preferable.

  When producing | generating a polyurethane resin (A), the usage-amount of the hydroxyl-containing compound (a1) which has a carboxyl group makes the acid value of a polyurethane resin (A) be in the range of 5-30 mgKOH / g.

A conventionally well-known polyol used in the case of the synthesis | combination of a polyurethane resin can be used for a polyol (a2).
Specific examples of the polyol (a2) include polyester polyol, polyether polyol, polycarbonate polyol, and other polyols.

  Polyester polyols include aliphatic dicarboxylic acids (eg succinic acid, adipic acid, sebacic acid, glutaric acid, azelaic acid etc.) and / or aromatic dicarboxylic acids (eg isophthalic acid, terephthalic acid etc.), low Molecular weight glycol (for example, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1,6-hexamethylene glycol, neopentyl glycol, 1,4-bishydroxymethylcyclohexane, etc. ), And those obtained by condensation polymerization.

Specific examples of such polyester polyols include polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polyneopentyl adipate diol, polyethylene / butylene adipate diol, polyneopentyl / hexyl adipate diol, poly-3- Examples thereof include methylpentane adipate diol, polybutylene isophthalate diol, polycaprolactone diol, and poly-3-methylvalerolactone diol.
Polyester polyol is superior in heat resistance compared to polyether polyol. Therefore, the polyester polyol is more advantageous than the polyether polyol in obtaining an adhesive having excellent heat resistance.

Specific examples of the polyether polyol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and random / block copolymers thereof.
Polyether polyol is superior in hydrolysis resistance compared to polyester polyol. Therefore, the polyether polyol is more advantageous than the polyester polyol in obtaining an adhesive having excellent hydrolysis resistance.

Specific examples of the polycarbonate polyol include polytetramethylene carbonate diol, polypentamethylene carbonate diol, polyneopentyl carbonate diol, polyhexamethylene carbonate diol, poly (1,4-cyclohexanedimethylene carbonate) diol, and random / Examples thereof include a block copolymer.
Polycarbonate polyol is excellent in hydrolysis resistance and heat resistance, and therefore can be suitably used as a polyol.
Among the polycarbonate polyols, polyhexamethylene carbonate is preferable from the viewpoint of cost and availability as a material.

Specific examples of other polyols include dimer diol and its hydrogenated product, polybutadiene polyol and its hydrogenated product, polyisoprene polyol and its hydrogenated product, acrylic polyol, epoxy polyol, polyether ester polyol, siloxane-modified polyol, α , Ω-polymethyl methacrylate diol, α, ω-polybutyl methacrylate diol, siloxane-modified polyol, and the like.
Among these, a diol obtained from a hydrogenated product of dimer diol and a hydrogenated product of polybutadiene polyol is excellent in hydrolysis resistance and heat resistance like polycarbonate diol, and therefore can be suitably used as a polyol.

The number average molecular weight of the polyol (a2) (Mn, by terminal functional group determination method) is not particularly limited, but is preferably 500 to 6,000.
When the number average molecular weight (Mn) of the polyol (a2) is too large, the cohesive force of the urethane bond is hardly expressed and the mechanical properties tend to be lowered.
In addition, when Mn is too large, the crystalline polyol may cause a whitening phenomenon when the adhesive is coated. Therefore, when used alone, the crystalline polyol must have Mn of 3,000 or less. It is preferred to use.
In addition, a polyol (a2) can be used individually by 1 type or in combination of 2 or more types.

As the polyol component (a), in addition to the polyol (a2) described above, a short-chain diol (a3) can be used as necessary.
Specific examples of the short-chain diol (a3) include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, and 1,6-hexamethylene glycol. , Aliphatic glycols such as neopentyl glycol, and alkylene oxide low molar adducts thereof (number average molecular weight less than 500 by terminal functional group determination method); 1,4-bishydroxymethylcyclohexane, 2-methyl-1,1-cyclohexanedi Alicyclic glycol such as methanol and its alkylene oxide low molar adduct (number average molecular weight less than 500, same as above); Aromatic glycol such as xylylene glycol and its alkylene oxide low molar adduct (less than number average molecular weight less than 500, same as above) Bisphenol A, thiobisphenol , Bisphenol and alkylene oxide low molar adducts of such sulfone bisphenol (number average molecular weight of less than 500, supra), and the like.

  In addition, when producing | generating a polyurethane resin (A), a polyhydric alcohol type compound can also be used as a material of a polyurethane resin (A) similarly to the short chain diol component (a3). Specific examples of the polyhydric alcohol compound include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, tris- (2-hydroxyethyl) isocyanurate, 1,1,1-trimethylolethane, 1,1,1. -Trimethylolpropane can be mentioned.

When the short chain polyol (a3) is used in combination with the polyol (a2), the short chain polyol (a3) is preferably a short chain diol.
As the short-chain diol, ethylene glycol, 1,3-propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,6-hexamethylene glycol, neopentyl glycol and the like are preferable, and ethylene is particularly preferable. Glycol, 1,3-butylene glycol, and 1,4-butylene glycol.
These short chain diols can be used singly or in combination of two or more.

As the polyisocyanate component (b), conventionally known polyisocyanate components used in the production of polyurethane resins can be used.
Specific examples of the polyisocyanate component (b) include toluene-2,4-diisocyanate, toluene-2,6-diisocyanate, mixtures thereof, 4-methoxy-1,3-phenylene diisocyanate, 4-isopropyl-1, 3-phenylene diisocyanate, 4-chloro-1,3-phenylene diisocyanate, 4-butoxy-1,3-phenylene diisocyanate, 2,4-diisocyanate diphenyl ether, 4,4'-methylenebis (phenylene isocyanate) (MDI), and crude Or polymeric MDI, durylene diisocyanate, xylylene diisocyanate (XDI), 1,5-naphthalene diisocyanate, benzidine diisocyanate, o-nitrobenzidine diisocyanate, 4,4'-diisocyanate Aromatic diisocyanates such as todibenzyl; aliphatic diisocyanates such as methylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,10-decamethylene diisocyanate; 1,4-cyclohexylene diisocyanate, 4,4 Cycloaliphatic diisocyanates such as' -methylenebis (cyclohexyl isocyanate), 1,5-tetrahydronaphthalene diisocyanate, isophorone diisocyanate, hydrogenated XDI; these diisocyanates and low molecular weight polyols are terminated with isocyanate Examples thereof include a polyurethane prepolymer obtained by reaction.

Of these polyisocyanate components (b), aromatic isocyanate is preferred from the viewpoint of obtaining an industrially stable, inexpensive and excellent heat-resistant adhesive, and particularly preferred are toluene-2,4-diisocyanate and toluene. -2,6-diisocyanate, mixtures thereof, 4,4'-methylenebis (phenylene isocyanate) (MDI), and crude or polymeric MDI. These polyisocyanate components (b) can be used singly or in combination of two or more.
In the case of an adhesive containing a polyurethane-urea resin, such as the adhesive of the cited document 1, it is possible to use an inexpensive one as described above as the polyisocyanate component used as the material of the polyurethane-urea resin. Since it is difficult, there is a problem that costs are increased.

In producing polyurethane-urea resins, polyamines are used as raw materials. However, in the adhesives containing polyurethane-urea resins, such as the adhesive of Cited Document 1, a small amount of polyamines usually remains. To do. And since this polyamine reacts with an epoxy resin, when an epoxy resin is contained in an adhesive agent, there exists a problem that stability of a solution-form adhesive agent may fall remarkably by this reaction.
However, since the adhesive does not substantially contain a polyurethane-urea resin, such a problem cannot occur.

(Method for producing polyurethane resin (A))
The polyurethane resin (A) can be produced by a conventionally known polyurethane production method.
Specifically, first, a hydroxyl group-containing compound (a1) having a carboxyl group, a polyol (a2), and a polyisocyanate component (b) in the presence or absence of an organic solvent containing no active hydrogen in the molecule. Then, a polyurethane resin (A) is obtained by reacting a reaction component comprising a short-chain polyol (a3) used as a chain extender as required. In general, the reaction component may be a blended composition having an equivalent ratio of isocyanate group to hydroxyl group of 0.8 to 1.25. In addition, the reaction may be usually performed at 20 to 150 ° C., preferably 60 to 110 ° C., by a one-shot method or a multistage method.

The weight average molecular weight (Mw) of the polyurethane resin (A) obtained as described above is 1,000 to 500,000, and the properties such as flexibility, adhesiveness, and heat resistance of the polyurethane resin are more. It is preferable because it is effectively exhibited.
The weight average molecular weight means a value measured by gel permeation chromatography (GPC). For example, it can be measured with the following apparatus and conditions.
(1) Equipment: Product name “HLC-8020” (manufactured by Tosoh Corporation)
(2) Column: Trade names “TSKgel G2000HXL”, “G3000HXL”, “G4000GXL” (manufactured by Tosoh Corporation)
(3) Solvent: THF
(4) Flow rate: 1.0 ml / min
(5) Sample concentration: 2 g / L
(6) Injection volume: 100 μL
(7) Temperature: 40 ° C
(8) Detector: Model number “RI-8020” (manufactured by Tosoh Corporation)
(9) Standard material: TSK standard polystyrene (manufactured by Tosoh Corporation)

In this embodiment, a catalyst can be used as necessary in the synthesis of the polyurethane resin.
Examples of the catalyst include dibutyltin laurate, dioctyltin laurate, stannous octoate, zinc octylate, and a salt of an organic acid or an inorganic acid such as tetra n-butyl titanate, an organic metal derivative, and triethylamine. Examples thereof include organic amines and diazabicycloundecene catalysts. The catalyst accelerates the synthesis reaction of the polyurethane resin. However, if the catalyst is used in excess, there is a risk of inducing a decomposition reaction that decomposes a substance other than the polyurethane resin. As a result, the resulting adhesive is inferior in heat resistance in a high temperature range and heat resistance in the long term. When using the catalyst, it is preferable to use an appropriate amount of the catalyst.

The polyurethane resin (A) may be synthesized without using a solvent or may be synthesized with an organic solvent.
As the organic solvent, an organic solvent inert to the isocyanate group or an organic solvent less active than the reaction component with respect to the isocyanate group can be used.
Specific examples of the organic solvent include ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; toluene, xylene, swazol (trade name, manufactured by Cosmo Oil Co., Ltd.), Solvesso (trade name, manufactured by Exxon Chemical) Aromatic hydrocarbon solvents; aliphatic hydrocarbon solvents such as n-hexane; alcohol solvents such as methanol, ethanol and isopropyl alcohol; ether solvents such as dioxane and tetrahydrofuran; ethyl acetate, butyl acetate, isobutyl acetate, etc. Ester solvents; glycol ether ester solvents such as ethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate, 3-methyl-3-methoxybutyl acetate, ethyl-3-ethoxypropionate Dimethylformamide, amide solvents such as dimethylacetamide; lactams solvents such as N- methyl-2-pyrrolidone and the like.
In particular, toluene and methyl ethyl ketone are preferable from the viewpoint of the solubility of the polyurethane resin, the drying property of the adhesive, and the like.

(Epoxy resin (B))
In the adhesive, the content of the epoxy resin (B) is preferably 20 to 100 parts by mass, more preferably 30 to 80 parts by mass with respect to 100 parts by mass of the polyurethane resin (A).
If the adhesive has too little epoxy resin, the crosslinking concentration may be low, and heat resistance may not be sufficient, while if the epoxy resin is too much, the cured coating becomes distorted or brittle, The flexibility as a urethane resin system may be lost.

  The epoxy resin (B) has an epoxy equivalent of 5,000 g / eq. It is preferable to contain the above phenoxy resin (h) and a trifunctional or higher polyfunctional epoxy resin (i). The adhesive has an epoxy equivalent of 5,000 g / eq. By containing the phenoxy resin (h) as described above, it becomes more excellent in long-term heat resistance. In addition, the adhesive contains a trifunctional or higher polyfunctional epoxy resin (i), so that the crosslink density is increased and the long-term heat resistance is further improved.

As the phenoxy resin (h), bisphenol A type phenoxy resin, bisphenol F type phenoxy resin, phenoxy resin having a bisphenol A type skeleton and a bisphenol F type skeleton in one molecule can be used. It can be used in combination of two or more.
The phenoxy resin (h) preferably has an epoxy equivalent of 5,000 or more, more preferably 7,000 or more.

The trifunctional or higher polyfunctional epoxy resin (i) is an epoxy resin having three or more epoxy groups per molecule.
As the polyfunctional epoxy resin (i) having three or more functions, a phenol novolac type epoxy resin, a bisphenol A type novolak epoxy resin, a trifunctional phenol type epoxy resin, a tetrafunctional type phenol epoxy resin, or the like can be used.
Specifically, phenol novolac type epoxy resin (jER152, jER154: manufactured by Mitsubishi Chemical), bisphenol A novolak type epoxy resin (jER157S65, jER157S70: manufactured by Mitsubishi Chemical), trifunctional phenol type epoxy resin (jER1032S50, jER1032H60), tetrafunctional A phenol type epoxy resin (jER1031S) etc. are mentioned. These can be used individually by 1 type or in combination of 2 or more types.

  The adhesive has an epoxy equivalent of 5,000 g / eq. The trifunctional or higher polyfunctional epoxy resin (i) is preferably contained in an amount of 10 to 200 parts by weight, more preferably 30 to 70 parts by weight, based on 100 parts by weight of the phenoxy resin (h).

  As an epoxy resin (B), in addition to a phenoxy resin (h) and a trifunctional or higher polyfunctional epoxy resin (i), an epoxy resin such as a bisphenol A type, a bisphenol F type, or a rubber-modified type may be used in combination. Is possible.

The epoxy resin (B) is preferably mixed with the polyurethane resin (A) in a state dissolved in an organic solvent.
Specific examples of the organic solvent include ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; toluene, xylene, swazol (trade name, manufactured by Cosmo Oil Co., Ltd.), Solvesso (trade name, manufactured by Exxon Chemical) Aromatic hydrocarbon solvents; aliphatic hydrocarbon solvents such as n-hexane; alcohol solvents such as methanol, ethanol and isopropyl alcohol; ether solvents such as dioxane and tetrahydrofuran; ethyl acetate, butyl acetate, isobutyl acetate, etc. Ester solvents; glycol ether ester solvents such as ethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate, 3-methyl-3-methoxybutyl acetate, ethyl-3-ethoxypropionate Dimethylformamide, amide solvents such as dimethylacetamide; lactams solvents such as N- methyl-2-pyrrolidone and the like.
In particular, toluene and methyl ethyl ketone are preferable in view of solubility of the epoxy resin, drying property of the adhesive, and the like.
Further, toluene and methyl ethyl ketone are preferable from the viewpoint that it is difficult to deactivate the isocyanate group as compared with the alcohol solvent.
In the case of an adhesive containing a polyurethane-urea resin like the adhesive of the cited document 1, since an alcohol solvent is usually used, there is a concern that an isocyanate group may be deactivated by alcohol. This deactivation of the isocyanate group can occur not only in the polyisocyanate component but also in a block type isocyanate-based crosslinking agent as described later.

It is preferable that the adhesive further contains an isocyanate-based crosslinking agent.
The adhesive contains an isocyanate crosslinking agent, so that the hydroxyl group of the epoxy resin and the isocyanate group of the isocyanate crosslinking agent react faster than the polyurethane resin (A) and the epoxy resin (B) undergo a crosslinking reaction. A crosslinked structure can be formed.

The isocyanate-based crosslinking agent is not particularly limited, but is a known one that has been used conventionally, such as an isocyanurate body, a burette body, an adduct body, a polymer body having a polyfunctional isocyanate group. Can be used.
For example, dimer of 2,4-toluylene diisocyanate, triphenylmethane triisocyanate, tris- (p-isocyanatephenyl) thiophosphite, polyfunctional aromatic isocyanate, polyfunctional aromatic aliphatic isocyanate, polyfunctional aliphatic Examples thereof include blocked polyisocyanates such as isocyanate, fatty acid-modified polyfunctional aliphatic isocyanate, and blocked polyfunctional aliphatic isocyanate, and polyisocyanate prepolymers.

Of these isocyanate crosslinking agents, diphenylmethane diisocyanate and tolylene diisocyanate are preferable if they are aromatic. If it is aliphatic, modified products such as hexamethylene diisocyanate and isophorone diisocyanate are preferred.
Moreover, as an isocyanate type crosslinking agent, what contains 3 or more of isocyanate groups in 1 molecule is preferable.
Furthermore, as the isocyanate-based crosslinking agent, the polyisocyanate multimer, adducts with other compounds, and urethane prepolymers obtained by reacting low molecular weight polyols or polyamines to become terminal isocyanates are also preferably used. Is done.
As preferred embodiments of the isocyanate-based crosslinking agent, the following compounds (1) to (8) are exemplified, but are not limited thereto.

The isocyanate cross-linking agent is preferably a block type depending on the relationship with the pot life of the coating liquid as an adhesive.
As the blocking agent for making the isocyanate crosslinking agent into a block type, methanol, phenol, methyl ethyl ketoxime, dimethyl malonate, 3,5-dimethylpyrazole and the like are preferably used.
Of these, methyl ethyl ketoxime and 3,5-dimethylpyrazole are particularly preferable. Methyl ethyl oxime is deblocked at a relatively low temperature, and 3,5-dimethylpyrazole is further deblocked at a lower temperature.

The isocyanate crosslinking agent is effective for improving heat resistance and weather resistance if it is in an appropriate amount.
However, if the amount of the isocyanate cross-linking agent used is too large, the coating film becomes hard and brittle and the performance as an adhesive deteriorates. For this reason, it is preferable that the said adhesive agent contains 2-10 mass parts of isocyanate crosslinking agents with respect to 100 mass parts of total amounts of a polyurethane resin (A) and an epoxy resin (B).

  The adhesive may further contain an additive as necessary. Additives include, for example, antioxidants (hindered phenols, phosphites, thioethers, etc.), light stabilizers (hindered amines, etc.), UV absorbers (benzophenones, benzotriazoles, etc.), gas discoloration stability Agents (hydrazine-based), metal deactivators and the like. These additives can be used individually by 1 type or in combination of 2 or more types.

(Adhesive and production method thereof)
The adhesive can be obtained by mixing the polyurethane resin (A), the epoxy resin (B) obtained as described above, and, if necessary, an isocyanate crosslinking agent.

The adhesive contains a polyurethane resin (A) and an epoxy resin (B), the polyurethane resin (A) has a carboxyl group, and the acid value of the polyurethane resin (A) is 5 to 30 mgKOH / g. It is.
Thereby, the said adhesive agent is excellent in heat resistance for a long time, and becomes excellent in adhesiveness.

The adhesive thus obtained is suitably applied to the adhesion of plastic films, particularly polyethylene terephthalate and polyethylene naphthalate.
The adhesive exhibits an effect of being excellent in long-term heat resistance and adhesiveness by being applied by various known coating methods such as gravure and spraying.
About the coating amount, it is preferable to apply the adhesive so that the thickness after drying is 1 to 50 μm.

(Paper sheet)
The paper-like sheet constituting the insulating paper is formed using fibers.
The fibers used to form the paper sheet include aromatic polyamide fibers, polyester fibers, polyether sulfide fibers, polyphenylene sulfide fibers, polypropylene fibers, polyether ether ketone fibers, polyethylene terephthalate fibers, arylate fibers, polyethylene naphthalate fibers. And organic fibers such as liquid crystal polyester fiber and polyethylene naphthalate fiber, and inorganic fibers such as glass fiber, rock wool, asbestos, boron fiber, alumina fiber, and carbon fiber. In addition, natural fibers such as silk and cotton, and semi-synthetic fibers such as cellulose are also included.
In addition, the paper-like sheet may be one in which only one of these fibers is used, or may be a mixture of a plurality of these.
The thickness of the paper sheet in the insulating paper is preferably 20 to 150 μm, from the viewpoint of being able to impart high mechanical characteristics to the insulating paper and being excellent in shape retention when bent, and the like. 60 μm is more preferable.

The paper sheet formed of the aromatic polyamide fiber is called a so-called “aramid paper” or the like using a wholly aromatic polyamide resin fiber as a main material from the viewpoint of better electrical insulation. A paper sheet is preferred.
As the aramid paper, a sheet mainly composed of fibers (fully aromatic polyamide fibers) made of a resin material other than an amide group composed of a benzene ring, such as a condensation polymer of phenylenediamine and phthalic acid. A shape can be used.
The aramid paper preferably has a basis weight of 5 g / m ² or more from the viewpoint that it has excellent mechanical properties and is not easily torn when bent.
As said aramid paper, what is marketed by the brand name "Nomex paper" from DuPont etc. can be used, for example.

(Polyester resin sheet)
Examples of the polyester resin of the polyester resin sheet constituting the insulating paper include polybutylene terephthalate resin, polyethylene terephthalate resin, polybutylene naphthalate resin, polyethylene naphthalate resin, and poly-1,4-cyclohexanedimethylene terephthalate resin. Can be mentioned.
The polyester resin preferably contains at least one of a polyethylene terephthalate resin, a polyethylene naphthalate resin, and a polybutylene terephthalate resin.
The polyester resin sheet is more preferably a low oligomer type polyethylene terephthalate resin sheet.
The low oligomer type polyethylene terephthalate resin sheet is preferably a low oligomer having an oligomer extraction amount of 0.5% by mass or less.
The oligomer extraction amount is obtained, for example, by boiling a sheet of 38 mm × 38 mm in 20 cc of xylene at 139 ° C. for 2 hours, slowly cooling it, taking out the sheet, and measuring the amount of oligomer in the xylene. It is done.
The amount of oligomer in xylene is determined from the absorbance at a measurement wavelength of 240 nm, and is determined from a calibration curve prepared in advance for the relationship between the concentration of the oligomer and the absorbance.
In addition, the measurement of a light absorbency can use UV-VIS-NIR spectrophotometer UV-3101PC made from SHIMADZU, for example.
The polyester resin sheet accounts for 29 to 62 mass%, more preferably 56 to 76 mass% of the polyester resin in the resin component contained.
The thickness of the polyester resin layer in the insulating paper is preferably 16 to 250 μm, more preferably 25 to 125 μm.

(Insulating paper and its manufacturing method)
As shown in FIG. 1, the insulating paper 1 has a laminated structure of five layers.
The insulating paper 1 includes a surface layer 2 on one side, a surface layer 2 ′ on the other side, and an intermediate layer 3 provided between these surface layers 2 and 2 ′. Each of these surface layers 2, 2 ′ is formed of the paper sheet. The intermediate layer 3 is formed of a polyester resin sheet.
The insulating paper 1 further includes two adhesive layers 4 and 4 ′ formed of the adhesive. The insulating paper 1 is configured by laminating the surface layers 2 and 2 ′ on the intermediate layer 3 through the adhesive layers 4 and 4 ′, respectively.
1-20 micrometers is preferable and, as for the thickness of each layer of the said adhesive bond layers 4 and 4 ', 5-10 micrometers is more preferable.

In the method for producing insulating paper, first, an adhesive is applied to both sides of a polyester resin sheet.
When the adhesive contains an organic solvent, the organic solvent is volatilized by heating to form an adhesive layer. The heating temperature for volatilizing the organic solvent is preferably 80 to 130 ° C. The heating time is preferably 1 to 10 minutes.
Next, a paper sheet is laminated on each layer of the formed adhesive layer. And the said insulating paper is obtained by carrying out the hardening reaction of the polyurethane resin (A) and epoxy resin which are contained in an adhesive bond layer by heating. The heating temperature for this curing reaction is preferably 80 to 130 ° C. The heating time is preferably 8 to 24 hours.
According to the above manufacturing method, the insulating paper 1 includes the first sheet constituting the surface layer 2 as the sheet material, the second sheet bonded to the first sheet via the adhesive, and the first sheet. The surface layer 2 ′ on the opposite side to the surface layer 2 that is configured is configured to include a third sheet bonded to the second sheet by the adhesive. The second sheet constitutes an intermediate layer 3 between the third sheet and the first sheet. The first sheet and the third sheet are paper sheets, and the second sheet is a polyester resin sheet.

  Since the insulating paper is excellent in heat resistance for a long time and is easy to manufacture, the insulating paper can be suitably used as an insulating paper used for at least one of a motor and an inverter. It can be suitably used as an insulating paper for a motor for insulation between the core and the winding coil or between the winding coils.

The insulating paper according to the present invention is not limited to the above embodiment. Further, the insulating paper according to the present invention is not limited to the above-described effects. The insulating paper according to the present invention can be variously modified without departing from the gist of the present invention.
For example, the insulating paper according to the present embodiment has a five-layer laminated structure, but the insulating paper according to the present invention is obtained by laminating the polyester resin sheet and the paper-like sheet via an adhesive, and then curing. If it is made to react, it may not be a 5 layer laminated structure, for example, a 3 layer laminated structure may be sufficient.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. In the examples, comparative examples, reference examples, and reference comparative examples, “parts” and “%” are based on mass unless otherwise specified.

(Test 1)
<Synthesis example of polyurethane resin (A)>
<Synthesis example of polyurethane resin: A1>
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen blowing tube, and a manhole was prepared. While replacing the inside of the reaction vessel with nitrogen, 200.0 g of polyhexamethylene carbonate diol having both terminal hydroxyl groups (Duranol: manufactured by Asahi Kasei Chemicals Corporation, number average molecular weight by terminal functional group quantification method = 2,000) 200.0 g, Neo Pentyl glycol (NPG) 25.3 g and dimethylolpropionic acid (DMPA) 4.0 g were charged. Next, 98.2 g of methyl ethyl ketone (MEK) was charged as a solvent, and the system was stirred. After the system became uniform, 93.2 g of 4,4′-diphenylmethane diisocyanate (MDI) was charged at 50 ° C. and reacted at 80 ° C. to obtain a reaction solution. The viscosity of the reaction solution is adjusted by diluting the reaction solution with methyl ethyl ketone (MEK) as a solvent, and the reaction is allowed to proceed until 2,270 cm ⁻¹ absorption due to the free isocyanate group measured by infrared absorption spectrum analysis disappears. Resin solution AA1 of polyurethane resin A1 was obtained. The obtained resin solution had a viscosity of 420 dPa · s / 20 ° C., a solid content of 30%, and the polyurethane resin had an acid value of 5.2 mgKOH / g. Moreover, the weight average molecular weight of polyurethane resin A1 measured by GPC was 83,000.

<Synthesis example of polyurethane resin: A2>
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen blowing tube, and a manhole was prepared. While replacing the inside of the reaction vessel with nitrogen, 200.0 g of polyhexamethylene carbonate diol having both terminal hydroxyl groups (Duranol: manufactured by Asahi Kasei Chemicals Corporation, number average molecular weight by terminal functional group quantification method = 2,000) 200.0 g, Neo Pentyl glycol (NPG) 25.3 g and dimethylolpropionic acid (DMPA) 8.0 g were charged. Next, 100.0 g of methyl ethyl ketone (MEK) was charged as a solvent, and the system was stirred. After the system became uniform, 100.8 g of 4,4′-diphenylmethane diisocyanate (MDI) was charged at 50 ° C. and reacted at 80 ° C. to obtain a reaction solution. The viscosity of the reaction solution is adjusted by diluting the reaction solution with methyl ethyl ketone (MEK) as a solvent, and the reaction is allowed to proceed until 2,270 cm ⁻¹ absorption due to the free isocyanate group measured by infrared absorption spectrum analysis disappears. Resin solution AA2 of polyurethane resin A2 was obtained. The obtained resin solution had a viscosity of 410 dPa · s / 20 ° C., a solid content of 30%, and the polyurethane resin had an acid value of 10.0 mgKOH / g. Moreover, the weight average molecular weight of polyurethane resin A2 measured by GPC was 79,000.

<Synthesis example of polyurethane resin: A3>
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen blowing tube, and a manhole was prepared. While replacing the inside of the reaction vessel with nitrogen, 200.0 g of polyhexamethylene carbonate diol having both terminal hydroxyl groups (Duranol: manufactured by Asahi Kasei Chemicals, number average molecular weight by terminal functional group determination method = 2,000), 1,3- 15.0 g of butanediol and 16.0 g of dimethylolpropionic acid (DMPA) were charged. Next, 99.0 g of methyl ethyl ketone (MEK) was charged as a solvent, and the system was stirred. After the system became uniform, 96.3 g of 4,4′-diphenylmethane diisocyanate (MDI) was charged at 50 ° C. and reacted at 80 ° C. to obtain a reaction solution. The viscosity of the reaction solution is adjusted by diluting the reaction solution with methyl ethyl ketone (MEK) as a solvent, and the reaction is allowed to proceed until 2,270 cm ⁻¹ absorption due to the free isocyanate group measured by infrared absorption spectrum analysis disappears. Resin solution AA3 of polyurethane resin A3 was obtained. The obtained resin solution had a viscosity of 500 dPa · s / 20 ° C., a solid content of 30%, and the polyurethane resin had an acid value of 20.5 mgKOH / g. Moreover, the weight average molecular weight of polyurethane resin A3 measured by GPC was 86,000.

<Synthesis example of polyurethane resin: A4>
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen blowing tube, and a manhole was prepared. While replacing the inside of the reaction vessel with nitrogen, 200.0 g of polyhexamethylene carbonate diol having both terminal hydroxyl groups (Duranol: manufactured by Asahi Kasei Chemicals Corporation, number average molecular weight by terminal functional group determination method = 2,000) 200.0 g, , 4-butanediol (7.0 g) and dimethylolpropionic acid (DMPA) (22.5 g) were charged. Next, 98.4 g of methyl ethyl ketone (MEK) was charged as a solvent, and the system was stirred. After the system became uniform, 86.4 g of 4,4′-diphenylmethane diisocyanate (MDI) was charged at 50 ° C. and reacted at 80 ° C. to obtain a reaction solution. The viscosity of the reaction solution is adjusted by diluting the reaction solution with methyl ethyl ketone (MEK) as a solvent, and the reaction is allowed to proceed until 2,270 cm ⁻¹ absorption due to the free isocyanate group measured by infrared absorption spectrum analysis disappears. Resin solution AA4 of polyurethane resin A4 was obtained. The obtained resin solution had a viscosity of 450 dPa · s / 20 ° C., a solid content of 30%, and the polyurethane resin had an acid value of 29.8 mgKOH / g. Moreover, the weight average molecular weight of polyurethane resin A4 measured by GPC was 83,000.

<Synthesis example of polyurethane resin: A5>
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen blowing tube, and a manhole was prepared. While replacing the inside of the reaction vessel with nitrogen, 200.0 g of polyhexamethylene carbonate diol having both terminal hydroxyl groups (Duranol: manufactured by Asahi Kasei Chemicals Corporation, number average molecular weight by terminal functional group determination method = 2,000) 200.0 g, , 4-butanediol (7.0 g) and dimethylolpropionic acid (DMPA) (22.5 g) were charged. Next, 89.6 g of methyl ethyl ketone (MEK) was charged as a solvent, and the system was stirred. After the system became uniform, 48.3 g of a mixture of toluene-2,4-diisocyanate and toluene-2,6-diisocyanate (80/20 wt%) was charged at 50 ° C. and reacted at 80 ° C. to react. A liquid was obtained. The viscosity of the reaction solution is adjusted by diluting the reaction solution with methyl ethyl ketone (MEK) as a solvent, and the reaction is allowed to proceed until 2,270 cm ⁻¹ absorption due to the free isocyanate group measured by infrared absorption spectrum analysis disappears. Resin solution AA5 of polyurethane resin A5 was obtained. The obtained resin solution had a viscosity of 200 dPa · s / 20 ° C., a solid content of 30%, and the polyurethane resin had an acid value of 20.9 mgKOH / g. Moreover, the weight average molecular weight of polyurethane resin A5 measured by GPC was 70,000.

<Synthesis example of polyurethane resin: A6>
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen blowing tube, and a manhole was prepared. While replacing the inside of the reaction vessel with nitrogen, hydrogenated dimer acid diol having hydroxyl groups at both ends (Prepol 2033: manufactured by Claude Japan Co., Ltd., number average molecular weight by terminal functional group quantification method = 542) 200.0 g, di 10.0 g of methylolpropionic acid (DMPA) was charged. Next, 90.0 g of methyl ethyl ketone (MEK) was charged as a solvent. After the system became uniform, 110.9 g of 4,4′-diphenylmethane diisocyanate (MDI) was charged at 50 ° C. and reacted at 80 ° C. to obtain a reaction solution. The viscosity of the reaction solution is adjusted by diluting the reaction solution with methyl ethyl ketone (MEK) as a solvent, and the reaction is allowed to proceed until 2,270 cm ⁻¹ absorption due to the free isocyanate group measured by infrared absorption spectrum analysis disappears. Resin solution AA6 of polyurethane resin A6 was obtained. The obtained resin solution had a viscosity of 300 dPa · s / 20 ° C., a solid content of 40%, and the polyurethane resin had an acid value of 13.0 mgKOH / g. Moreover, the weight average molecular weight of polyurethane resin A6 measured by GPC was 62,000.

<Synthetic Comparative Example of Polyurethane Resin: X1>
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen blowing tube, and a manhole was prepared. While replacing the inside of the reaction vessel with nitrogen, 200.0 g of polyhexamethylene carbonate diol having both terminal hydroxyl groups (Duranol: manufactured by Asahi Kasei Chemicals Corporation, number average molecular weight by terminal functional group quantification method = 2,000) 200.0 g, Neo Pentyl glycol (NPG) 28.5 g and dimethylolpropionic acid (DMPA) 2.0 g were charged. Next, 98.8 g of methyl ethyl ketone (MEK) was charged as a solvent, and the system was stirred. After the system became uniform, 97.2 g of 4,4′-diphenylmethane diisocyanate (MDI) was charged at 50 ° C. and reacted at 80 ° C. to obtain a reaction solution. The viscosity of the reaction solution is adjusted by diluting the reaction solution with methyl ethyl ketone (MEK) as a solvent, and the reaction is allowed to proceed until 2,270 cm ⁻¹ absorption due to the free isocyanate group measured by infrared absorption spectrum analysis disappears. Resin solution XX1 of polyurethane resin X1 was obtained. The obtained resin solution had a viscosity of 380 dPa · s / 20 ° C., a solid content of 30%, and the polyurethane resin had an acid value of 2.6 mgKOH / g. Moreover, the weight average molecular weight of polyurethane resin X1 measured by GPC was 75,000.

<Synthetic Comparative Example of Polyurethane Resin: X2>
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen blowing tube, and a manhole was prepared. While replacing the inside of the reaction vessel with nitrogen, 200.0 g of polyhexamethylene carbonate diol having both terminal hydroxyl groups (Duranol: manufactured by Asahi Kasei Chemicals Corporation, number average molecular weight by terminal functional group determination method = 2,000) 200.0 g, , 4-butanediol 7.0 g, and dimethylolpropionic acid (DMPA) 29.0 g were charged. Next, 101.1 g of methyl ethyl ketone (MEK) was charged as a solvent, and the system was stirred. After the system became uniform, 98.5 g of 4,4′-diphenylmethane diisocyanate (MDI) was charged at 50 ° C. and reacted at 80 ° C. to obtain a reaction solution. The viscosity of the reaction solution is adjusted by diluting the reaction solution with methyl ethyl ketone (MEK) as a solvent, and the reaction is allowed to proceed until 2,270 cm ⁻¹ absorption due to the free isocyanate group measured by infrared absorption spectrum analysis disappears. Resin solution XX2 of polyurethane resin X2 was obtained. The obtained resin solution had a viscosity of 470 dPa · s / 20 ° C., a solid content of 30%, and the polyurethane resin had an acid value of 36.3 mgKOH / g. Moreover, the weight average molecular weight of polyurethane resin X2 measured by GPC was 85,000.

<Synthesis Comparative Example of Polyurethane-Urea Resin: X3>
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen blowing tube, and a manhole was prepared. While replacing the inside of the reaction vessel with nitrogen, 200.0 g of polyhexamethylene carbonate diol having both terminal hydroxyl groups (Duranol: manufactured by Asahi Kasei Chemicals Corporation, number average molecular weight by terminal functional group determination method = 2,000) 200.0 g, , 3-butanediol 5.0 g and dimethylolpropionic acid (DMPA) 15.0 g were charged. Next, 145.2 g of toluene was charged as a solvent, and the system was stirred. After the system became uniform, isophorone diisocyanate (IPDI) 118.8 g was charged at 60 ° C. and reacted at 80 ° C. for 3 hours to obtain a reaction solution. When NCO% of the prepolymer in the reaction solution was measured, a prepolymer having an NCO% of 4.64% was obtained. Thereafter, 303.2 g of toluene was added to the reaction solution, and the reaction solution was cooled to 30 ° C.
Next, 45.5 g of isophoronediamine (IPDA) was weighed and diluted with 448.4 g of isopropanol alcohol (IPA). Next, the mixture of IPDA and IPA was stirred well and then gradually added to the reaction solution containing the prepolymer. The mixture was added until the viscosity of the reaction solution was in an appropriate state. When 90% of the total amount of IPDA and IPA was mixed, 2,270 cm due to free isocyanate groups measured by infrared absorption spectrum analysis. ^When absorption of ^-1 was confirmed, it almost disappeared. Dilution with methyl ethyl ketone (MEK) as a solvent gave a resin solution XX3 of polyurethane-urea resin X3. The obtained resin solution had a viscosity of 310 dPa · s / 20 ° C., a solid content of 30%, and the polyurethane-urea resin had an acid value of 16.3 mgKOH / g. Moreover, the weight average molecular weight of the polyurethane-urea resin X3 measured by GPC was 76,000.

<Example of dissolution of epoxy resin (B)>
<Example of epoxy resin dissolution: h1>
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen blowing tube, and a manhole was prepared. While replacing the inside of the reaction vessel with nitrogen, 400.0 g of bisphenol A type phenoxy resin (epoxy equivalent: 7,800 g / eq., JER1256: manufactured by Mitsubishi Chemical Corporation) was charged, and methyl ethyl ketone (MEK) was used as a solvent while stirring. ) 600.0 g was charged, and the temperature inside the system was raised to 60 ° C. to completely dissolve it. A dissolved product hh1 of the phenoxy resin h1 was obtained. The solid content of the obtained phenoxy resin solution was 40%.

<Example of epoxy resin dissolution: h2>
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen blowing tube, and a manhole was prepared. Phenoxy resin having a bisphenol A type skeleton and a bisphenol F type skeleton in one molecule while replacing the inside of the reaction vessel with nitrogen (epoxy equivalent: 9,000 g / eq., JER4275: manufactured by Mitsubishi Chemical Corporation) 400.0 g was charged, and 600.0 g of methyl ethyl ketone (MEK) was charged as a solvent while stirring, and the temperature inside the system was raised to 60 ° C. to completely dissolve it. A dissolved product hh2 of the phenoxy resin h2 was obtained. The solid content of the obtained phenoxy resin solution was 40%.

<Example of epoxy resin dissolution: i1>
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen blowing tube, and a manhole was prepared. While replacing the inside of the reaction vessel with nitrogen, 800.0 g of a phenol novolak-type epoxy resin (trifunctional or higher) (epoxy equivalent: 177 g / eq., JER154: manufactured by Mitsubishi Chemical Corporation) was charged, and the solvent was stirred. As a solution, 200.0 g of methyl ethyl ketone (MEK) was charged, and the system was heated to 60 ° C. and completely dissolved. A dissolved product ii1 of the epoxy resin i1 was obtained. The solid content of the obtained epoxy resin solution was 80%.

<Example of epoxy resin dissolution: i2>
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen blowing tube, and a manhole was prepared. While replacing the inside of the reaction vessel with nitrogen, 800.0 g of bisphenol A novolak type epoxy resin (trifunctional or higher) (epoxy equivalent: 208 g / eq., JER157S70: manufactured by Mitsubishi Chemical Corporation) was charged and stirred. As a solvent, 200.0 g of methyl ethyl ketone (MEK) was charged, and the system was heated to 60 ° C. and completely dissolved. A dissolved product ii2 of the epoxy resin i2 was obtained. The solid content of the obtained epoxy resin solution was 80%.

<Example of epoxy resin dissolution: i3>
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen blowing tube, and a manhole was prepared. While replacing the inside of the reaction vessel with nitrogen, 800.0 g of a trifunctional phenol type epoxy resin (epoxy equivalent: 169 g / eq., JER1032H60: manufactured by Mitsubishi Chemical Corporation) was charged, and methyl ethyl ketone (MEK) as a solvent while stirring. ) 200.0 g was charged, and the system was heated to 60 ° C. and completely dissolved. A dissolved product ii3 of the epoxy resin i3 was obtained. The solid content of the obtained epoxy resin solution was 80%.

<Example of epoxy resin dissolution: i4>
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen blowing tube, and a manhole was prepared. While replacing the inside of the reaction vessel with nitrogen, 800.0 g of a tetrafunctional phenol type epoxy resin (epoxy equivalent: 200 g / eq., JER1031S: manufactured by Mitsubishi Chemical Corporation) was charged, and methyl ethyl ketone (MEK) as a solvent while stirring. ) 200.0 g was charged, and the system was heated to 60 ° C. and completely dissolved. A dissolved product ii4 of the epoxy resin i4 was obtained. The solid content of the obtained epoxy resin solution was 80%.

<Example of epoxy resin dissolution: Y1>
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen blowing tube, and a manhole was prepared. While replacing the inside of the reaction vessel with nitrogen, 400.0 g of a bisphenol A type epoxy resin (epoxy equivalent: 2,850 g / eq., JER1009: manufactured by Mitsubishi Chemical Corporation) was charged and stirred with methyl ethyl ketone ( MEK) 600.0 g was charged, and the system was heated to 60 ° C. and completely dissolved. A dissolved product YY1 of the epoxy resin Y1 was obtained. The resulting epoxy resin solution had a solid content of 40%.

<Preparation of adhesive>
[Adhesive of Reference Example and Adhesive of Reference Comparative Example]
Adhesives were obtained using the various materials described above and below.
As the resin solution containing the polyurethane resin (A), the resin solutions AA1 to AA6 of Synthesis Examples A1 to A6 were used, and the resin solutions XX1 and XX2 of Synthesis Comparative Examples X1 and X2 were used.
Moreover, the resin solution XX3 of the synthesis comparative example X3 was used as a resin solution containing a polyurethane-urea resin.

  As an epoxy resin solution containing the epoxy resin (B), obtained from the epoxy resin solutions ii to ii4 obtained from the phenoxy resin solutions hh1 and hh2 obtained from the epoxy resin dissolution examples h1 and h2, i1 to ii4, Y1. The obtained epoxy resin solution YY1 and a low molecular weight bisphenol A type epoxy resin (epoxy equivalent: 186 g / eq., JER828: manufactured by Mitsubishi Chemical Corporation) were used.

  Methyl ethyl ketoxime block type (C1) (BI 7984: Baxenden) and 3,5-dimethylpyrazole type (C2) (BI 7951: Baxenden) were used as the block isocyanate type crosslinking agent.

  The above various samples were mixed at the blending ratios shown in Table 1 below to produce adhesives of Reference Examples and Reference Comparative Examples. The adhesives of the reference examples and reference comparative examples were adjusted with methyl ethyl ketone (MEK) so that the solid content was 30%.

[Coating of adhesive to PET film]
The adhesive was diluted with methyl ethyl ketone (MEK) to a solid content of 25%. Then, the diluted adhesive is applied to the entire surface of one side of a PET film (length: 210 mm, width: 150 mm, thickness: 100 μm, Lumirror: manufactured by Panac Co., Ltd.), and then dried at 100 ° C. for 1 minute. A PET film with an adhesive layer was prepared. The coating was performed so that the thickness of the adhesive layer after drying was 12 μm.

[Initial adhesion 1]
A PET film with an adhesive layer and a separately prepared PET film so that the adhesive layer of the PET film with an adhesive layer and the uncoated surface of the separately prepared PET film having the same shape as the PET film are in contact with each other. Overlaid and left for 10 seconds. And the PET film prepared separately was peeled from the PET film with an adhesive layer, and the adhesion was evaluated according to the following criteria.
A: A strong resistance is felt during peeling and a sound is produced.
○: Sounds when peeling.
X: Easily peels off and does not make sound when peeled off.

[Initial adhesion 2]
The PET film with the adhesive layer and the aramid paper are overlapped so that the adhesive layer of the PET film with the adhesive layer and the surface of the aramid paper (the same shape as the PET film with the adhesive layer) are in contact with each other. It stuck using the laminator adjusted to 80 degreeC. And at room temperature, the aramid paper was peeled off from the PET film with an adhesive layer, and the adhesion was evaluated according to the following criteria.
A: Aramid paper breaks the material.
○: Aramid paper remains on a part of the adhesive layer and peels off.
X: Easy to peel off.

[Processability]
The PET film with the adhesive layer and the aramid paper are overlapped so that the adhesive layer of the PET film with the adhesive layer and the surface of the aramid paper (the same shape as the PET film with the adhesive layer) are in contact with each other. It stuck using the laminator adjusted to 80 degreeC. And processing aptitude was evaluated according to the following criteria.
A: Affixed neatly.
○: Although distortion can be confirmed, there is no wrinkle or float.
X: Pasting does not work well due to distortion or wrinkles, and there is floating.

[Heat resistance evaluation: 255 ° C]
The PET film with the adhesive layer and the aramid paper are overlapped so that the adhesive layer of the PET film with the adhesive layer and the surface of the aramid paper (the same shape as the PET film with the adhesive layer) are in contact with each other. It stuck using the laminator adjusted to 80 degreeC.
The diluted adhesive (solid content 25%) was applied to the entire surface opposite to the adhesive layer side of the PET film with the adhesive layer, and then dried at 100 ° C. for 1 minute. The coating was performed so that the thickness of the adhesive layer after drying was 12 μm. Then, the newly formed adhesive layer of the PET film with the adhesive layer and the surface of the aramid paper (the same shape as the PET film with the adhesive layer) are in contact with each other, and the aramid The paper was laminated and pasted using a laminator adjusted to 80 ° C.
Thereby, a laminated sheet having a configuration of aramid paper / PET / aramid paper was obtained.
And this laminated sheet was left to stand in 100 degreeC oven for 12 hours, and hardening reaction was advanced.
Next, this laminated sheet was cut out to 5 cm × 5 cm, left in an oven at 255 ° C. for 24 hours, and subjected to heat resistance evaluation according to the following criteria.
A: No change after treatment at 255 ° C.
○: Deformation and swelling are not observed with the treatment at 255 ° C.
X: After treatment at 255 ° C., peeling and swelling are observed.

[Heat resistance evaluation TG-DTA]
An adhesive (solid content 30%) was applied on the entire surface of one side of the release paper, and then dried at 100 ° C. for 1 minute. The coating was performed so that the thickness of the adhesive layer after drying was 12 μm.
And the release paper with an adhesive layer was cured by heating at 100 ° C. for 12 hours to obtain a test piece.
Next, using TG-DTA (manufactured by Rigaku Corporation, TG8120), the temperature was raised from normal temperature to 5 ° C./min in an atmosphere of 100 ml / min to obtain a TG-DTA curve. Then, the heat resistance was judged by paying attention to the temperature at which 5% weight decreased (5% temperature decrease) and the temperature at which 50% weight decreased (50% temperature decrease). In addition, 5% temperature reduction of TG-DTA shows short-term heat resistance, and 50% temperature reduction shows long-term heat resistance. In the evaluation, heat resistance was judged from TG-DTA as follows.
(Double-circle): 5% reduction temperature is 280 degreeC or more, and 50% reduction temperature is 350 degreeC or more.
○: Except for ◎, 5% decrease temperature is 200 ° C. or more, and 50% decrease temperature is 300 ° C. or more.
×: Other than ◎ or ○

[Solution stability (storage stability)]
The coating liquid as an adhesive was put in a container and sealed, and stored in an oven at 40 ° C. for 4 weeks.
In addition, the initial viscosity (25 ° C.) of the coating liquid as an adhesive before being put into the oven and the viscosity of the coating liquid as an adhesive when stored in an oven at 40 ° C. for 4 weeks and then returned to 25 ° C. ( Viscosity after treatment).
In addition, the viscosity was measured by the method based on JISZ8803: 2011 using the single cylindrical rotational viscometer.
And storage stability was evaluated according to the following criteria.
○: The viscosity after treatment is less than twice the initial viscosity.
X: The viscosity after a process is 2 times or more of initial viscosity.

  The results are shown in Table 2 below.

  From the results of Test 1 above, it can be seen that the adhesive according to the reference example is an adhesive having good heat resistance as an adhesive, particularly as an adhesive for plastic films.

(Test 2)
<Example 1>
The adhesive of Reference Example 2 was diluted with methyl ethyl ketone and toluene (MEK: TOL = 2: 1 (mass ratio)) to a solid content of 25%.
Next, the diluted adhesive was applied to both sides of a polyethylene terephthalate (PET) film (length: 350 mm, width: 210 mm, thickness: 25 μm) as a polyester resin sheet.
And the organic solvent was volatilized by heating PET film with which the adhesive agent was apply | coated for 3 minutes at 110 degreeC, and the adhesive bond layer was formed.
Next, aramid paper (length: 350 mm, width: 210 mm, thickness: 50 μm) (manufactured by DuPont, trade name “Nomex Paper”) as a paper sheet was laminated on each layer of the formed adhesive layer.
Then, by heating (heating temperature: 100 ° C., heating time: 12 hours), the polyurethane resin (A) and the epoxy resin contained in the adhesive layer were subjected to a curing reaction to obtain insulating paper.
The thickness of the adhesive layer in the insulating paper was 7 μm.

<Example 2>
An insulating paper was obtained in the same manner as in Example 1 except that a polyethylene naphthalate (PEN) film having a thickness of 50 μm was used as the polyester resin sheet.

<Example 3>
An insulating paper was obtained in the same manner as in Example 1 except that a PET film having a thickness of 25 μm was used and that aramid paper having a thickness of 37 μm was used.

<Example 4>
An insulating paper was obtained in the same manner as in Example 1 except that a PET film having a thickness of 38 μm was used.

<Comparative Example 1>
Insulation in the same manner as in Example 1 except that an adhesive containing acrylic resin, bisphenol A type epoxy resin, phenol novolac type epoxy resin, phenol aralkyl epoxy resin, and imidazole as a curing agent was used. I got paper.

<Comparative example 2>
An insulating paper was obtained in the same manner as in Example 2 except that an adhesive containing an acrylic resin and an isocyanate curing agent was used as the adhesive.

<Comparative Example 3>
An insulating paper was obtained in the same manner as in Example 3 except that an adhesive containing a polyester-based polyurethane resin was used as the adhesive.

<Comparative example 4>
Commercially available insulating paper (Laminated sheet of aramid paper (thickness: 50 μm) / adhesive layer (thickness: 10 μm) / PET film (thickness: 25 μm) / adhesive layer (thickness: 7 μm) / aramid paper (thickness: 50 μm)) (Vertical: 350 mm, horizontal: 210 mm) was used as the insulating paper of Comparative Example 4.

<Comparative Example 5>
A PET film having a thickness of 125 μm was used as the insulating sheet of Comparative Example 5.

<Comparative Example 6>
A PEN film having a thickness of 125 μm was used as the insulating sheet of Comparative Example 6.

<Comparative Example 7>
An insulating paper was obtained in the same manner as in Example 2 except that an adhesive containing a polyester-based polyurethane resin was used as the adhesive.

<Oil resistance test>
The insulating paper and insulating sheet of each Example and Comparative Example were immersed in 150 ° C. oil for 0 hours, 500 hours, 1000 hours, and 1500 hours to obtain evaluation samples.
Then, the evaluation sample was pulled in the longitudinal direction at a chuck interval of 180 mm and a tensile speed of 200 mm / min, the maximum load was read (n = 5), and the arithmetic average value of the read values was taken as the tensile strength.
And ratio (%) of the tensile strength after being immersed in oil with respect to the initial tensile strength (0 hour) was calculated as tensile strength retention. The results are shown in FIG.

<Moist heat test>
The insulating paper of each example and comparative example was placed in an atmosphere of a temperature of 85 ° C. and a humidity of 85% for 0 hour, 250 hours, 500 hours, and 1000 hours to obtain evaluation samples.
And the tensile strength retention was calculated | required similarly to the oil-proof test mentioned above. The results are shown in FIG.

<Cooling cycle test>
The insulating paper of each example and comparative example was placed in an atmosphere of −40 ° C. for 30 minutes, and then placed in an atmosphere of 150 ° C. for 30 minutes as one cycle of the cooling cycle, and the insulating paper of each example and comparative example was cooled. An evaluation sample was obtained by placing under cycle 0, 250, 500, and 1000 cycles.
And the tensile strength retention was calculated | required similarly to the oil-proof test mentioned above. The results are shown in FIG.

<Heat-resistant life test>
The insulating paper of each Example and Comparative Example was placed in an atmosphere of 200 ° C. for 0 hour, 250 hours, 500 hours, 750 hours, 1000 hours, and 2000 hours to obtain evaluation samples.
And the tensile strength was calculated | required like the oil-proof test mentioned above.
Next, an approximate curve of y = a × ln (x) + b where time was x and tensile strength was y was obtained (a and b were obtained). Then, from this approximate curve and the initial (0 hour) tensile strength, a time (tensile strength half-time) in which the tensile strength was half of the initial value was determined.
Moreover, the insulating paper of each Example and Comparative Example was placed in an atmosphere of 220 ° C. for 0 hour, 250 hours, 500 hours, 750 hours, and 1000 hours to obtain an evaluation sample, and the tensile strength half-life was obtained by the above method. .
Furthermore, the insulating paper of each example and comparative example was placed in an atmosphere of 240 ° C. for 0 hour, 250 hours, 500 hours, 750 hours, 1000 hours, 2000 hours, and an evaluation sample was obtained. Asked.
Moreover, the insulating paper of each Example and Comparative Example was placed in an atmosphere of 250 ° C. for 0 hour, 50 hours, 100 hours, 250 hours, and 500 hours to obtain an evaluation sample, and the tensile strength half time was obtained by the above method. .
Furthermore, the insulating paper of each Example and Comparative Example was placed in an atmosphere of 255 ° C. for 0 hour, 50 hours, 100 hours, 250 hours, and 500 hours to obtain an evaluation sample, and the tensile strength half time was obtained by the above method. .
Moreover, the insulating paper of each Example and Comparative Example was placed in an atmosphere of 260 ° C. for 0 hour, 50 hours, 100 hours, and 250 hours to obtain an evaluation sample, and the tensile strength half-life was obtained by the above method.
The results are shown in FIG.

<Peel test>
The insulating paper of each example and comparative example was placed in an atmosphere of 100 ° C., 150 ° C., 180 ° C., 200 ° C., 220 ° C., 240 ° C., 250 ° C., 260 ° C. for 10 minutes to obtain an evaluation sample.
Under the above atmosphere, using the evaluation sample, AIKOH ENGINEERING tensile tester "MODEL-1840VT", HUTEC combined test thermostat, longitudinal direction at a peeling angle of 180 ° and a pulling speed of 300 mm / min. A peel test was conducted to peel the aramid paper from the PET film or PEN film, and the peel force (adhesive force) was measured.
The results are shown in Table 3 below.
In addition, the ratio (%) of the peeling force at 260 ° C. to the peeling force at 100 ° C. was calculated as the retention rate.

<Measurement of volume resistivity after moisture absorption storage>
After the insulating paper of each Example and Comparative Example was stored under normal conditions, the volume resistivity of the insulating paper was measured.
The volume resistivity was determined by the method of JIS C 2139: 2008.
Moreover, the volume resistivity of the insulating paper was measured after the insulating paper of each Example and Comparative Example was immersed in tap water at room temperature for 24 hours.
Furthermore, the volume resistivity of the insulating paper was measured after placing the insulating paper of each example and comparative example in an atmosphere of 85 ° C. and 85% humidity for 24 hours.
Moreover, about the insulating paper of each Example and a comparative example, after implementing the 121 degreeC x 0.48MPa pressure cooker test (it is also called "PCT") by "EHS-411M" made from ESPEC, the volume of insulating paper is carried out. The resistivity was measured.
The results are shown in Table 4 below.

  From the results of Test 2 above, it can be seen that the insulating paper according to the example is excellent in oil resistance, heat and humidity resistance, and cold and heat resistance. It can also be seen that the insulating paper according to the example has a significantly improved heat-resistant life.

(Test 3)
<Test Examples 1-32>
The following materials were mixed at the blending ratios shown in Tables 5 and 6 below to prepare adhesives of Test Examples 1 to 32.
The “phenol novolac type epoxy resin and curing accelerator” means a mixture in which a phenol novolac type epoxy resin and a curing accelerator are mixed. Moreover, in Test Examples 25-31, the mixture which mixed the bisphenol A type epoxy resin, the phenol novolak type epoxy resin, the hardening accelerator, and the phenol aralkyl epoxy resin was used. Furthermore, the adhesives of Test Examples 1 to 32 were adjusted with methyl ethyl ketone (MEK) so that the solid content was 30%.
Polyurethane resin Polyester resin Acrylic resin Bisphenol A type epoxy resin: Epoxy equivalent (182-192)
Phenol novolac type epoxy resin Phenol aralkyl epoxy resin Curing accelerator: 2-Undecylimidazole

<Test Examples 33 to 42>
The materials described in (Test 1) were mixed at the blending ratios shown in Table 7 below to prepare adhesives for Test Examples 33 to 42.
In addition, the adhesives of Test Examples 33 to 42 were adjusted with methyl ethyl ketone (MEK) so that the solid content was 30%.

<Adhesion of aramid paper after heating for 100 hours>
The adhesives of Test Examples 1 to 42 were diluted with methyl ethyl ketone (MEK) to a solid content of 25%.
Then, the diluted adhesive was applied to the entire surface of one side of the aramid paper, and then dried at 100 ° C. for 1 minute to prepare an aramid paper with an adhesive layer. In addition, coating was performed so that the thickness of the adhesive bond layer after drying might be 10 micrometers.
Next, the aramid paper with the adhesive layer and the aramid separately prepared so that the adhesive layer of the aramid paper with the adhesive layer and the uncoated surface of the separately prepared aramid paper having the same shape as the aramid paper are in contact with each other. The paper was superposed and pasted using a laminator adjusted to 80 ° C. to obtain a laminated sheet.
And this laminated sheet was left to stand in 100 degreeC oven for 12 hours, the curing reaction was advanced, and the test sheet was obtained.
Next, the test sheet is cut out to 100 mm × 100 mm, heated in an atmosphere of 200 ° C., 220 ° C., 240 ° C., and 260 ° C. for 100 hours. After heating, the presence or absence of floating or peeling is visually observed, Was evaluated for adhesion (n = 3 to 5).
○: Neither floating nor peeling was observed.
X: At least one of floating and peeling was observed.
The results are shown in Tables 8 and 9.

<Thermogravimetry / differential thermal analysis>
Using a thermogravimetric / differential thermal analyzer (TG / DTA), the rate of weight loss by heating of the cured products of the adhesives of Test Examples 30 and 39 was measured.
The results are shown in FIG.

  As shown in Tables 8, 9, 10 and FIG. 6, the adhesive of Test Example 39 has a larger thermal weight reduction rate when the cured product is heated alone than the adhesive of Test Example 30, It can be seen that the insulating paper has a role of improving heat resistance.

(Test 4)
<Example 5>
An insulating paper was obtained in the same manner as in Example 1 except that the thickness of the adhesive layer in the insulating paper was 20 μm.

<Example 6>
An insulating paper was obtained in the same manner as in Example 5 except that a PET film having a thickness of 38 μm was used.

<Example 7>
An insulating paper was obtained in the same manner as in Example 5 except that a PET film having a thickness of 50 μm was used.

<Comparative Example 8>
An insulating paper was obtained in the same manner as in Comparative Example 7 except that the thickness of the adhesive layer in the insulating paper was 30 μm.

<Comparative Example 9>
An insulating paper was obtained in the same manner as in Comparative Example 8 except that a PET film having a thickness of 125 μm was used.

<Comparative Example 10>
An insulating paper was obtained in the same manner as in Example 7 except that a commercially available adhesive was used as the adhesive.

<Comparative Example 11>
An insulating paper was obtained in the same manner as in Comparative Example 10 except that a PET film having a thickness of 150 μm was used.

The comparative tracking index (CTI) of the insulating papers of Examples 5 to 7 and Comparative Examples 8 to 11 was measured. The comparative tracking index (CTI) was measured according to the method described in JIS C2134: 2007.
The results are shown in Table 11.
FIG. 7 shows the relationship between the thickness of the insulating paper and the comparative tracking index (CTI) for Examples 5 to 7 in which the adhesive of Reference Example 2 was used.
Further, FIG. 8 shows the relationship between the thickness of the insulating paper and the comparative tracking index (CTI) in Comparative Examples 8 and 9 in which an adhesive containing a polyester polyurethane resin is used.
Furthermore, in FIG. 9, the relationship between the thickness of the insulating paper about Comparative Examples 10 and 11 using a commercially available adhesive and the comparative tracking index (CTI) is shown.

  As shown in Table 11 and FIG. 7, when the adhesive of Reference Example 2 was used, the value of the comparative tracking index (CTI) increased rapidly when the thickness of the insulating paper was increased.

  1: insulating paper, 2, 2 ': surface layer, 3: intermediate layer, 4, 4': adhesive layer

Claims (10)

Used for at least one of motor and inverter,
At least two sheets are bonded with an adhesive,
The adhesive is a thermosetting adhesive containing a polyurethane resin (A) and an epoxy resin (B),
The polyurethane resin (A) has a carboxyl group,
The insulating paper whose acid value of the said polyurethane resin (A) is 5-30 mgKOH / g.   The epoxy resin (B) has an epoxy equivalent of 5,000 g / eq. The insulating paper of Claim 1 containing the phenoxy resin which is the above, and the polyfunctional epoxy resin more than trifunctional.   The insulating paper according to claim 1 or 2, wherein the content of the epoxy resin (B) is 20 to 100 parts by mass with respect to 100 parts by mass of the polyurethane resin (A).   The insulating paper according to any one of claims 1 to 3, wherein the polyurethane resin (A) has a weight average molecular weight of 1,000 to 500,000. Further containing an isocyanate-based crosslinking agent;
The content of the isocyanate-based crosslinking agent is 2 to 10 parts by mass with respect to 100 parts by mass of the total amount of the polyurethane resin (A) and the epoxy resin (B). Insulation paper. As the sheet material, it has a first sheet constituting a surface layer, and a second sheet bonded to the first sheet via the adhesive,
The first sheet is a paper sheet;
The insulating paper according to any one of claims 1 to 5, wherein the second sheet is a polyester resin sheet containing a polyester resin. The sheet material further includes a third sheet constituting a surface layer opposite to the surface layer constituted by the first sheet,
The second sheet constitutes an intermediate layer between the third sheet and the first sheet,
The insulating paper according to claim 6, wherein the third sheet is a paper-like sheet and is bonded to the second sheet by the adhesive.   The insulating paper according to claim 6 or 7, wherein the polyester resin sheet contains at least one of a polyethylene terephthalate resin, a polyethylene naphthalate resin, and a polybutylene terephthalate resin.   The insulating paper according to claim 8, wherein the polyester resin sheet is a low oligomer type polyethylene terephthalate resin sheet.   The insulating paper according to any one of claims 6 to 9, wherein the paper sheet is formed of an aromatic polyamide fiber.