Thermoplastic adhesive sheet, method for using same, and adhesive structure

Abstract

Provided is a thermoplastic adhesive sheet exhibiting high insulation properties and high shear adhesive strength. The thermoplastic adhesive sheet includes a thermoplastic resin and an insulating reinforcing-fiber sheet, and has an adhesive surface that adheres by the action of the thermoplastic resin. The ratio of the volume of the insulating reinforcing-fiber sheet relative to the total volume of the thermoplastic resin and the insulating reinforcing-fiber sheet is 2-50 vol%. For example, in the thermoplastic adhesive sheet, both the surfaces of the thermoplastic adhesive sheet may be adhesive surfaces, and the exposure rate of the insulating reinforcing-fiber sheet on each of the adhesive surfaces may be less than 10%.

Description

Thermoplastic adhesive sheet, method of use thereof, and adhesive structure Related Applications

[0001] This application claims priority from Japanese Patent Application No. 2024-008301, filed on January 23, 2024, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a thermoplastic adhesive sheet comprising a thermoplastic resin and an insulating reinforcing fiber sheet, having an adhesive surface bonded by the thermoplastic resin, a method for using the thermoplastic adhesive sheet, and an adhesive structure comprising a thermoplastic adhesive sheet and an adherend that is integrated in contact with at least a portion of the adhesive surface.

[0003] Conventionally, motors have been used with permanent magnets in the rotor or stator. The permanent magnets are inserted into the holes in the rotor or stator, and the gaps are filled with a thermosetting resin such as epoxy resin. The resin is then cured to bond the permanent magnets together. However, when using a thermosetting resin, a long curing time is required to increase the shear bond strength, resulting in a long manufacturing cycle time. Furthermore, contact between the rotor or stator and the permanent magnet cannot be prevented, and the permanent magnet must be insulated to ensure electrical insulation.

[0004] Therefore, in recent years, sheet-shaped composite materials containing insulating reinforcing fibers and thermoplastic resins have been proposed as fixing materials. For example, Patent Document 1 (WO 2020 / 183945) discloses a space filling material that is composed of reinforcing fibers as an expandable material and a resin, where the reinforcing fibers have multiple intersections and at least some of the intersections are bonded with the resin, and fills a predetermined space at least in the thickness direction by expansion stress when heated, and describes its use as a molding material for fixing permanent magnets.

[0005] Furthermore, with regard to a sheet-like composite material containing insulating reinforcing fibers and a thermoplastic resin, for example, Patent Document 2 (WO 2018 / 150978) describes a resin-attached reinforcing fiber fabric in which a thermoplastic resin is attached to at least one surface of a reinforcing fiber fabric, and the mass W per unit area of ​​the reinforcing fiber fabric is 25 g / m２ More than 400g / m ２ The reinforcing fiber woven fabric has an air permeability P of 0.1 cm or less. ３ / cm ２ / s or more 300cm ３ / cm ２ / s or less, the melting point of the thermoplastic resin is in the range of 70°C or more and 300°C or less, the proportion of the mass of the reinforcing fiber fabric to the total mass of the resin-adhered reinforcing fiber fabric is in the range of 20% by mass or more and 90% by mass or less, the coverage rate C of the reinforcing fiber fabric surface by the thermoplastic resin is in the range of 30% or more and less than 100%, and the resin adhesion coefficient A is in the range of 35 or more and 135 or less.

[0006] Patent Document 3 (JP-A-8-207200) describes a thermoplastic resin composite material in which a plurality of laminated glass fiber fabrics are impregnated and integrated with a thermoplastic resin, in which the volume percentage of glass fiber is 50±5% and the mass of the glass fiber fabric laminated on the surface is 105±2 g / m ２ A fiber-reinforced thermoplastic resin composite material is disclosed, characterized in that the mass ratio of warp yarns to weft yarns is in the range of 1±0.05.

[0007] Patent Document 4 (JP-A-8-11133) discloses a molding sheet material that is a laminate formed by impregnating 2-24 sheets of mechanically washed glass fabric and a thermoplastic engineering plastic, the glass fiber volume being 40-60% and the thickness being 0.7-4 mm.

[0008] International Publication No. 2020 / 183945 International Publication No. 2018 / 150978 JP 8-207200 JP 8-11133

[0009] However, in recent years, there has been an increasing demand for high rotation speed motors used in electric vehicles and the like, and in the case of such high rotation speed motors, the method of fixing a permanent magnet by pressing it with expansion stress, such as the space filler described in Patent Document 1, does not provide sufficient fixing force.

[0010] Furthermore, Patent Documents 2 to 4 only describe sheet-like composite materials used to manufacture molded products, and do not describe applications for bonding adherends such as permanent magnets.

[0011] It is therefore an object of the present invention to provide a thermoplastic adhesive sheet that exhibits high insulating properties and shear adhesive strength.

[0012] As a result of intensive research to solve the above problems, the inventors discovered that by incorporating an insulating reinforcing fiber sheet at a specific volume ratio in a thermoplastic adhesive sheet having an adhesive surface that is bonded by a thermoplastic resin, the sheet can be bonded to the adherend and exhibit high shear adhesive strength, while also suppressing contact as an insulating material for the adherend, thereby ensuring insulation, and thus completed the present invention.

[0013] That is, the present invention can be configured in the following aspects. [Aspect 1] A thermoplastic adhesive sheet comprising a thermoplastic resin and an insulating reinforcing fiber sheet, having an adhesive surface bonded by the thermoplastic resin, wherein the volume ratio of the insulating reinforcing fiber sheet to the total volume of the thermoplastic resin and the insulating reinforcing fiber sheet is 2 to 50 vol% (preferably 5 to 48 vol%, more preferably 10 to 45 vol%, and even more preferably 13 to 40 vol%). [Aspect 2] The thermoplastic adhesive sheet according to Aspect 1, wherein both sides of the thermoplastic adhesive sheet are adhesive surfaces, and the exposed ratio of the insulating reinforcing fiber sheet on each of the adhesive surfaces is less than 10% (preferably less than 5%, more preferably 2% or less, and most preferably 0%). [Aspect 3] The thermoplastic adhesive sheet according to Aspect 1 or 2, wherein the insulating reinforcing fiber sheet is a glass fiber fabric. [Aspect 4] The thermoplastic adhesive sheet according to any one of Aspects 1 to 3, wherein the insulating reinforcing fiber sheet has a thickness of 10 to 150 μm (preferably 20 to 120 μm, more preferably 30 to 100 μm). [Aspect 5] The thermoplastic adhesive sheet according to any one of Aspects 1 to 4, wherein the weight per unit area of ​​the insulating reinforcing fiber sheet, Mf, is 10 to 79 g / m. ２ (preferably 12 to 75 g / m２ , more preferably 15 to 70 g / m ２ ) and the theoretical thickness T represented by the following formula (1) is 20 to 150 μm (preferably 30 to 120 μm, more preferably 50 to 100 μm): T=Mp / σp+Mf / σf (1) (wherein T is the theoretical thickness [μm], Mp is the weight per unit area of ​​the thermoplastic resin [g / m ２ ], σp: density of thermoplastic resin [g / cm ３ ], Mf: weight per unit area of ​​insulating reinforcing fiber sheet [g / m ２ ], σf: density of insulating reinforcing fiber [g / cm ３ ]) [Aspect 6] The thermoplastic adhesive sheet according to any one of Aspects 1 to 5, wherein the thermoplastic resin has a glass transition temperature of 100°C or higher (preferably 120°C or higher, more preferably 150°C or higher). [Aspect 7] The thermoplastic adhesive sheet according to any one of Aspects 1 to 6, wherein the thermoplastic resin is an amorphous thermoplastic resin. [Aspect 8] The thermoplastic adhesive sheet according to any one of Aspects 1 to 7, wherein the thermoplastic resin is at least one thermoplastic resin selected from the group consisting of polyetherimide-based resins, polyetheretherketone-based resins, phenoxy-based resins, and polycarbonate-based resins. [Aspect 9] An adhesive structure comprising the thermoplastic adhesive sheet according to any one of Aspects 1 to 8 and an adherend integrated in contact with at least a portion of the adhesive surface of the thermoplastic adhesive sheet. [Aspect 10] A method of using the thermoplastic adhesive sheet according to any one of Aspects 1 to 8, comprising interposing the thermoplastic adhesive sheet between adherends, and heating the sheet to a temperature equal to or higher than the softening point of the thermoplastic resin while applying pressure from at least one of the adherends in the lamination direction of the thermoplastic adhesive sheet, thereby bonding the adherends together. [Aspect 11] A method of using the thermoplastic adhesive sheet according to Aspect 10, wherein one sheet of the thermoplastic adhesive sheet is interposed between the adherends.

[0014] As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms, including "at least one," unless the content clearly dictates otherwise. As used herein, the terms "and / or," "at least one," and "one or more" include any and all combinations of the associated listed items.

[0015] It should be noted that any combination of at least two elements disclosed in the claims and / or the specification and / or the drawings is included in the present invention, and in particular any combination of two or more of the claims set forth in the claims is included in the present invention.

[0016] The thermoplastic adhesive sheet of the present invention adheres to an adherend, exhibits high shear adhesive strength, and can ensure the insulating properties of the adherend.

[0017] The present invention will be more clearly understood from the following description of preferred embodiments, taken in conjunction with the accompanying drawings. The drawings are not necessarily drawn to scale and are exaggerated to illustrate the principles of the present invention. However, the embodiments and drawings are merely for illustration and explanation purposes and should not be used to define the scope of the present invention, which is defined by the appended claims.

[0023] Figure 1 is a schematic cross-sectional view of a first embodiment of a method for using a thermoplastic adhesive sheet, showing the state before bonding; Figure 2 is a schematic cross-sectional view of the first embodiment of a method for using a thermoplastic adhesive sheet, showing the state after bonding; Figure 3 is a schematic cross-sectional view of a second embodiment of a method for using a thermoplastic adhesive sheet, showing the state before bonding; and Figure 4 is a schematic cross-sectional view of the second embodiment of a method for using a thermoplastic adhesive sheet, showing the state after bonding.

[0018] <Thermoplastic adhesive sheet> The thermoplastic adhesive sheet includes a thermoplastic resin and an insulating reinforcing fiber sheet, and has an adhesive surface that is bonded by the thermoplastic resin. The thermoplastic adhesive sheet is softened by heating, allowing it to bond an adherend in contact with the adhesive surface. The adhesive surface refers to a surface that is primarily composed of a thermoplastic resin, and may be, for example, a surface that, in a plan view, comprises 50% or more of the entire area of ​​the thermoplastic adhesive sheet. Even if only one side of the thermoplastic adhesive sheet is the adhesive surface, depending on the type of thermoplastic resin or insulating reinforcing fiber sheet, the adhesive conditions, etc., the thermoplastic resin can flow to the other side (non-adhesive surface) and bond an adherend in contact with the non-adhesive surface.

[0019] In the thermoplastic adhesive sheet, the volume ratio of the insulating reinforcing fiber sheet to the total volume of the thermoplastic resin and the insulating reinforcing fiber sheet is 2 to 50 vol%. By incorporating the insulating reinforcing fiber sheet at a specific volume ratio, it is possible to achieve both the shape retention of the insulating reinforcing fiber sheet and the adhesiveness of the thermoplastic resin. When an adherend is bonded to the thermoplastic adhesive sheet, the sheet can bond to the adherend and exhibit high shear bond strength. Furthermore, the insulating reinforcing fiber sheet acts as an insulator for the adherend, suppressing contact between the insulating reinforcing fiber sheet and the adherend, thereby ensuring insulation. If the volume ratio of the insulating reinforcing fiber sheet is too small, the shape retention of the insulating reinforcing fiber sheet may be insufficient, which may cause the thermoplastic resin to protrude from the adhesive surface during bonding and contaminate the adherend. Furthermore, contact with the adherend may not be prevented, potentially resulting in an insufficient insulation. On the other hand, if the volume ratio of the insulating reinforcing fiber sheet is too large, the shear bond strength when bonded to the adherend is low, possibly due to an insufficient contact area between the thermoplastic resin and the adherend, and sufficient adhesion may not be exhibited. The volume ratio of the insulating reinforcing fiber sheet to the total volume of the thermoplastic resin and the insulating reinforcing fiber sheet is preferably 5 to 48 vol%, more preferably 10 to 45 vol%, and still more preferably 13 to 40 vol%. May be.

[0020] The thermoplastic resin is, for example, a vinyl resin (vinyl group CH ２ ═CH— or vinylidene group CH ２Polymers synthesized from monomers having the formula: =C< or derivatives thereof; for example, polyolefin resins such as polyethylene and polypropylene; acrylic resins such as polymethyl methacrylate; polyvinyl chloride resins; polystyrene resins; polyamide resins such as aliphatic polyamide resins (polyamide 6, polyamide 66, polyamide 11, polyamide 12, polyamide 610, polyamide 612, etc.), semi-aromatic polyamide resins, and wholly aromatic polyamide resins; polyester resins such as polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate; Examples of the thermoplastic resin include fluorine-based resins such as polytetrafluoroethylene resins; thermoplastic polyimide resins such as semi-aromatic polyimide resins, polyamideimide resins, and polyetherimide resins; polysulfone resins such as polysulfone resins and polyethersulfone resins; polyphenylene sulfide resins; modified polyphenylene ether resins; polyetherketone resins such as polyetheretherketone resins and polyetherketoneketone resins; phenoxy resins; polycarbonate resins; amorphous polyarylate resins; and liquid crystal polyester resins such as wholly aromatic polyester resins. These thermoplastic resins may be used alone or in combination of two or more.

[0021] Furthermore, for applications requiring heat resistance, it is preferable to use a thermoplastic resin having a glass transition temperature of 100°C or higher, more preferably 120°C or higher, and even more preferably 150°C or higher. There is no particular upper limit, but from the viewpoint of bonding at relatively low temperatures, it may be 300°C or lower. For example, thermoplastic resins having the above glass transition temperature may be used, such as semi-aromatic polyamide resins, polytetrafluoroethylene resins, thermoplastic polyimide resins, polysulfone resins, polyphenylene sulfide resins, modified polyphenylene ether resins, polyether ketone resins, phenoxy resins, polycarbonate resins, and amorphous polyarylate resins. In this specification, the glass transition temperature is a value measured by the method described in the Examples below.

[0022] From the viewpoint of adhesiveness, it is preferable to use an amorphous thermoplastic resin as the thermoplastic resin. Examples of amorphous thermoplastic resins include acrylic resins, polyvinyl chloride resins, polystyrene resins, thermoplastic polyimide resins, polysulfone resins, modified polyphenylene ether resins, phenoxy resins, polycarbonate resins, and amorphous polyarylate resins. In this specification, "amorphous" can be confirmed by the presence or absence of an endothermic peak in differential scanning calorimetry. If the endothermic peak is very broad and the endothermic peak cannot be clearly identified, it may be determined to be substantially amorphous.

[0023] Among the above thermoplastic resins, from the viewpoints of heat resistance and adhesiveness, at least one thermoplastic resin selected from the group consisting of polyetherimide resins, polyetheretherketone resins, phenoxy resins, and polycarbonate resins is preferred, and from the viewpoints of heat resistance and adhesiveness when the adherend is a metal material, polyetherimide resins are more preferred.

[0024] The thermoplastic resin may contain various additives within the range that does not impair the effects of the present invention.

[0025] The form of the thermoplastic resin in the thermoplastic adhesive sheet is not particularly limited, and may be, for example, a sheet (thermoplastic resin sheet) of fabrics such as woven fabrics, knitted fabrics, and nonwoven fabrics, or a film laminated with an insulating reinforcing fiber sheet, in which case the thermoplastic resin sheet may form the adhesive surface. Furthermore, for applications in which the sheet is inserted into a narrow space for adhesion, the insulating reinforcing fiber sheet may be at least partially impregnated with a matrix resin. For example, the thermoplastic adhesive sheet may include a shape-retaining layer in which the insulating reinforcing fiber sheet is impregnated with a thermoplastic resin, and an adhesive layer containing a thermoplastic resin present as an outermost layer on at least one surface of the shape-retaining layer.

[0026] The insulating reinforcing fiber sheet is composed of insulating reinforcing fibers, which may be inorganic or organic. Examples of inorganic fibers include glass fibers, silicon nitride fibers, silica fibers, and alumina fibers. Organic fibers are not particularly limited as long as their glass transition temperature or melting point is higher than the softening point of the thermoplastic resin. Examples include liquid crystal polyester fibers, wholly aromatic polyamide fibers (aramid fibers), polybenzazole fibers, polyimide fibers, and polyphenylene sulfide fibers. In this specification, the softening point mainly refers to the heat distortion temperature, and may be, for example, the deflection temperature under load (JIS K 7207). In particular, in the case of an amorphous thermoplastic resin, it refers to its glass transition temperature. Of these, the insulating reinforcing fibers are preferably inorganic fibers from the viewpoint of excellent heat resistance. Furthermore, glass fibers are more preferable from the viewpoint of adhesiveness.

[0027] The insulating reinforcing fibers are preferably long fibers from the viewpoint of suppressing expansion of the thermoplastic adhesive sheet when heated and ensuring insulation. In this specification, long fibers are fibers that are continuous to a certain length and can be distinguished from short fibers that are intentionally cut to a predetermined fiber length, and may be, for example, continuous fibers with a fiber length of 50 mm or more.

[0028] Examples of insulating reinforcing fiber sheets include woven fabrics, knitted fabrics, braided fabrics, and nonwoven fabrics. From the viewpoint of suppressing expansion of the thermoplastic adhesive sheet, insulating reinforcing fiber woven fabrics are preferred, and from the viewpoint of adhesiveness, glass fiber woven fabrics are more preferred. Examples of weaves of insulating reinforcing fiber woven fabrics include plain weave, satin weave, and twill weave, but from the viewpoint of thickness uniformity, plain weave is preferred.

[0029] The insulating reinforcing fiber sheet may have a thickness of 10 to 150 μm, preferably 20 to 120 μm, and more preferably 30 to 100 μm, from the viewpoints of shape retention and insulation properties and insertion into narrow portions. In this specification, the thickness of the insulating reinforcing fiber sheet refers to the overall thickness when multiple insulating reinforcing fiber sheets are stacked, and is a value measured by the method described in the examples below.

[0030] The insulating reinforcing fiber sheet has a weight per unit area Mf of 10 to 79 g / m ２ and preferably 12 to 75 g / m ２ , more preferably 15 to 70 g / m ２ In this specification, the weight per unit area (basis weight) is a value measured by the method described in the examples below.

[0031] The insulating reinforcing fiber sheet may have a known surface treatment agent attached to its surface to improve adhesion to the thermoplastic resin. For example, when the insulating reinforcing fiber is an inorganic fiber (e.g., glass fiber), a silane coupling agent may be attached to the surface of the insulating reinforcing fiber sheet. Known silane coupling agents can be used, such as epoxy silane, vinyl silane, amino silane, chlorosilane, mercaptosilane, (meth) acrylic silane, and cationic silane.

[0032] When the adherend is a metal material, the thermoplastic adhesive sheet preferably uses a combination of polyetherimide resin as the thermoplastic resin and glass fiber fabric as the insulating reinforcing fiber sheet. Because polyetherimide resin has good adhesion to both metal materials and glass fibers, it can improve the shear bond strength when adhering a metal material to the thermoplastic adhesive sheet.

[0033] The thermoplastic adhesive sheet may have adhesive surfaces on both sides. When both sides have adhesive surfaces, adherends can be bonded to each other via the thermoplastic adhesive sheet, exhibiting high shear adhesive strength. Furthermore, the thermoplastic adhesive sheet can suppress contact between adherends, ensuring insulation. For example, the thermoplastic adhesive sheet may include a shape-retaining layer in which an insulating reinforcing fiber sheet is impregnated with a thermoplastic resin, and adhesive layers containing a thermoplastic resin present as outermost layers on both sides of the shape-retaining layer.

[0034] When a thermoplastic adhesive sheet has adhesive surfaces on both sides, from the viewpoint of suppressing warping of the sheet and ease of insertion into narrow spaces, the exposure rate of the insulating reinforcing fiber sheet on each adhesive surface is preferably less than 10%, more preferably less than 5%, even more preferably 2% or less, and most preferably 0%. Reducing the exposure rate of the insulating reinforcing fiber sheet on the adhesive surface of the thermoplastic adhesive sheet can suppress the formation of irregularities due to the surface shape of the insulating reinforcing fiber sheet, thereby reducing surface frictional resistance and facilitating insertion into narrow spaces. Furthermore, when the volume ratio of the insulating reinforcing fiber sheet is relatively small, a large exposure rate of the insulating reinforcing fiber sheet tends to cause warping in the thermoplastic adhesive sheet. However, reducing the exposure rate of the insulating reinforcing fiber sheet on both adhesive surfaces can suppress warping in the thermoplastic adhesive sheet and improve handleability. In this specification, the exposure rate of the insulating reinforcing fiber sheet refers to the ratio of the area occupied by the insulating reinforcing fiber sheet to the total area on the surface of the thermoplastic adhesive sheet, and is a value measured by the method described in the Examples below.

[0035] From the viewpoint of inserting the thermoplastic adhesive sheet into a narrow space (for example, a gap of about 50 to 5000 μm) and adhering the adherend with high precision, the theoretical thickness T, expressed by the following formula (1), may be 20 to 150 μm, preferably 30 to 120 μm, and more preferably 50 to 100 μm: T=Mp / σp+Mf / σf (1) (where T: theoretical thickness [μm], Mp: weight per unit area of ​​thermoplastic resin [g / m ２ ], σp: density of thermoplastic resin [g / cm ３ ], Mf: weight per unit area of ​​insulating reinforcing fiber sheet [g / m ２ ], σf: density of insulating reinforcing fiber [g / cm ３ ])

[0036] From the viewpoint of adhesiveness, it is preferable that the thermoplastic adhesive sheet has low expansion upon heating. If the expansion is high, voids may form within the thermoplastic adhesive sheet when heated and bonded to an adherend, and these voids may result in a decrease in shear adhesive strength. For example, the thermoplastic adhesive sheet may have a maximum thicknesswise expansion rate of 50% or less, preferably 20% or less, more preferably 10% or less, and even more preferably 1% or less. In this specification, the maximum thicknesswise expansion rate refers to the expansion rate when heated for 10 minutes at a temperature equal to or higher than the softening point of the thermoplastic resin without pressure. The expansion rate is calculated from the thicknesses of the thermoplastic adhesive sheet before and after heating by dividing the thickness of the thermoplastic adhesive sheet after heating by the thickness of the thermoplastic adhesive sheet before heating x 100.

[0037] From the viewpoint of adhesiveness, it is preferable that the thermoplastic adhesive sheet does not substantially contain binder components that can be used in the production of thermoplastic resin sheets or insulating reinforcing fiber sheets. For example, the content of binder components in the thermoplastic adhesive sheet may be 1% by weight or less. When the thermoplastic resin in the thermoplastic adhesive sheet is a fabric, or when such a fabric is used as a precursor to impregnate an insulating reinforcing fiber sheet using a heat press or the like, it is preferable to use fabrics that can be formed without using binder components (e.g., spunbond nonwoven fabrics, meltblown nonwoven fabrics, etc.). Furthermore, while sizing agents containing binder components may be used in the manufacturing process of insulating reinforcing fiber sheets, it is preferable that these are removed by washing in a subsequent process. Examples of binder components include polyolefin resins, polyamide resins, polyester resins, acrylic resins, polyvinyl alcohol resins, and polyurethane resins.

[0038] The thermoplastic adhesive sheet may have a shear bond strength of 19 MPa or more, preferably 20 MPa or more, more preferably 23 MPa or more, and even more preferably 25 MPa or more, as measured by the method described in the Examples below. The upper limit of the shear bond strength is not particularly limited, but may be, for example, 50 MPa or less.

[0039] From the viewpoint of ease of insertion into narrow spaces, the thermoplastic adhesive sheet may have a damage load of 80 g or more, preferably 100 g or more, and more preferably 200 g or more, as measured by the method described in the Examples below. The upper limit of the damage load is not particularly limited, but may be, for example, 500 g or less.

[0040] Examples of methods for producing a thermoplastic adhesive sheet include, when forming a laminated sheet of a thermoplastic resin sheet and an insulating reinforcing fiber sheet, a method of overlapping a thermoplastic resin sheet and an insulating reinforcing fiber sheet, or a method of coating an insulating reinforcing fiber sheet with a thermoplastic resin. For example, from the viewpoint of easily adjusting the volume ratio of the insulating reinforcing fiber sheet, a method for producing a thermoplastic adhesive sheet may include a step of laminating a thermoplastic resin sheet and an insulating reinforcing fiber sheet. The thermoplastic resin sheet may be a sheet composed of the above-mentioned thermoplastic resin, and examples of the sheet shape include fabrics such as woven fabrics, knitted fabrics, and nonwoven fabrics, and films. From the viewpoint of not containing a binder component, the thermoplastic resin sheet is preferably a binder-free fabric (e.g., spunbond nonwoven fabric, meltblown nonwoven fabric, etc.) or a film. Furthermore, from the viewpoints of the uniformity, shapeability, and impregnation of the insulating reinforcing fiber sheet of the thermoplastic resin sheet, it is more preferable that the thermoplastic resin sheet is a meltblown nonwoven fabric. The insulating reinforcing fiber sheet may be a fiber sheet composed of the above insulating reinforcing fibers, and examples of the fiber sheet shape include woven fabric, knitted fabric, braided fabric, nonwoven fabric, etc. The insulating reinforcing fiber sheet is preferably an insulating reinforcing fiber woven fabric from the viewpoint of suppressing expansion of the obtained thermoplastic adhesive sheet.

[0041] As long as an adhesive surface can be formed and the volume ratio of the insulating reinforcing fiber sheet can be adjusted, the configuration of the laminated sheet of the thermoplastic resin sheet and the insulating reinforcing fiber sheet obtained by the lamination process is not limited, and it may include one or more thermoplastic resin sheets and one or more insulating reinforcing fiber sheets. For example, from the viewpoint of forming an adhesive surface, it is preferable that the thermoplastic resin sheet is included so that it forms the outermost layer of at least one of the thermoplastic resin sheets. Furthermore, from the viewpoint of forming both sides of the thermoplastic adhesive sheet as adhesive surfaces, it is preferable that the thermoplastic resin sheet is included so that it forms the outermost layer of both of the thermoplastic resin sheets. For example, the laminated sheet of the thermoplastic resin sheet and the insulating reinforcing fiber sheet obtained by the lamination process may be configured in the following order: one or more thermoplastic adhesive sheets / one or more insulating reinforcing fiber sheets / one or more thermoplastic adhesive sheets. In this case, one thermoplastic resin sheet and the other thermoplastic resin sheet may be composed of the same type of thermoplastic resin or different types of thermoplastic resins, but from the viewpoint of adhesion, it is preferable that they are composed of the same type of thermoplastic resin.

[0042] The thermoplastic adhesive sheet may be a laminated sheet of a thermoplastic resin sheet and an insulating reinforcing fiber sheet obtained by a lamination process. However, when forming a sheet in which at least a portion of the thermoplastic resin is impregnated into the insulating reinforcing fiber sheet, methods for producing a thermoplastic adhesive sheet include a method in which the laminated sheet is heat-pressed to soften and flow the thermoplastic resin sheet, thereby impregnating the insulating reinforcing fiber sheet, or a method in which the insulating reinforcing fiber sheet is immersed in molten thermoplastic resin. For example, from the viewpoint of reducing the exposure rate of the insulating reinforcing fiber sheet, a method for producing a thermoplastic adhesive sheet may include a step of heating a laminated sheet of a thermoplastic resin sheet and an insulating reinforcing fiber sheet to a temperature above the softening point of the thermoplastic resin and applying pressure in the thickness direction to heat press. By adjusting conditions such as the volume ratio of the thermoplastic resin sheet to the insulating reinforcing fiber sheet, the lamination mode of the laminated sheet, the temperature, pressure, and time of the heat press, it is possible to form an adhesive surface composed of a thermoplastic resin matrix and having a reduced exposure rate of the insulating reinforcing fiber sheet.

[0043] The heating temperature in the heat press may be set in accordance with the softening point or decomposition temperature of the thermoplastic resin used, and is preferably equal to or higher than the softening point of the thermoplastic resin. For example, when the thermoplastic resin is crystalline, the heating temperature is preferably in the range of equal to or higher than the melting point of the thermoplastic resin and equal to or lower than (melting point + 100)°C. When the thermoplastic resin is amorphous, the heating temperature is preferably equal to or higher than the glass transition temperature of the thermoplastic resin and equal to or lower than (glass transition temperature + 200)°C.

[0044] The pressure applied during hot pressing is not particularly limited, and may be, for example, 0.01 MPa or more, preferably 1 MPa or more, and more preferably 5 MPa or more. The upper limit is not particularly limited, and may be, for example, about 20 MPa. The time required for hot pressing is also not particularly limited, but since exposure to high temperatures for a long period of time may cause the thermoplastic resin to deteriorate or flow, it is preferable to perform the hot pressing for a relatively short period of time, and may be, for example, within 10 minutes, preferably within 1 minute, and more preferably within 30 seconds. The lower limit is not particularly limited, and may be, for example, about 0.1 seconds.

[0045] The adherend is not particularly limited as long as it has a softening temperature higher than that of the thermoplastic resin of the thermoplastic adhesive sheet, and may be, for example, an inorganic material, a fiber-reinforced thermosetting resin, or a fiber-reinforced thermoplastic resin. In particular, from the viewpoint of protection from heat during adhesion, the adherend may be an inorganic material, or more preferably a metal material.

[0046] <Adhesive Structure> The adhesive structure may include a thermoplastic adhesive sheet and an adherend that is in contact with and integrated with at least a portion of the adhesive surface of the thermoplastic adhesive sheet. The adhesive structure allows the thermoplastic adhesive sheet and the adherend to be handled as a single unit, and the adherend can be used to bond another adherend. For example, the thermoplastic adhesive sheet and the adherend can be inserted as a single unit into a narrow portion, and the adherend can be adhered and fixed to the narrow portion.

[0047] The bonded structure can be produced, for example, by contacting at least a portion of the adhesive surface of a thermoplastic adhesive sheet with an adherend and heating the sheet at a temperature above the softening point of the thermoplastic resin to soften the thermoplastic resin and bond the adherend. Alternatively, the bonded structure can be produced by laminating a thermoplastic resin sheet and an insulating reinforcing fiber sheet to form a thermoplastic adhesive sheet so that the thermoplastic resin sheet and the adherend are in contact with each other, and then heating the sheet at a temperature above the softening point of the thermoplastic resin to soften the thermoplastic resin and bond the adherend while impregnating the insulating reinforcing fiber sheet. When bonding the adherend, the adherend may be bonded by heating while applying pressure in the direction of contact between the adhesive surface and the adherend.

[0048] The adhesive structure may have another adherend adhered to the adhesive surface on the opposite side to the adhesive surface of the thermoplastic adhesive sheet to which the adherend is integrated, or, if the adherend is integrated into part of the adhesive surface of the thermoplastic adhesive sheet, the other adherend may be adhered to the part of the adhesive surface of the thermoplastic adhesive sheet to which the adherend is integrated but to which the adherend is not integrated.

[0049] <Method of Using the Thermoplastic Adhesive Sheet> The thermoplastic adhesive sheet can be bonded to an adherend by contacting at least a portion of its adhesive surface with the adherend and heating it to a temperature above the softening point of the thermoplastic resin to soften the thermoplastic resin. Even if one side of the thermoplastic adhesive sheet is the adhesive surface and the other side is the non-adhesive surface, depending on the type of thermoplastic resin and insulating reinforcing fiber sheet, the adhesive conditions, etc., the thermoplastic resin can flow to the non-adhesive surface and bond the adherend in contact with the non-adhesive surface.

[0050] The thermoplastic adhesive sheet can bond adherends together. For example, each adherend may be bonded to a different surface of the thermoplastic adhesive sheet, or each adherend may be bonded to a different portion of the same surface of the thermoplastic adhesive sheet. Because the insulating properties of the thermoplastic adhesive sheet can be ensured by the insulating reinforcing fiber sheet, it is preferable to bond each adherend to a different surface of the thermoplastic adhesive sheet.

[0051] A method of using a thermoplastic adhesive sheet may involve placing the thermoplastic adhesive sheet between adherends, applying pressure from at least one of the adherends in the stacking direction of the thermoplastic adhesive sheet, and heating the adherends to a temperature above the softening point of the thermoplastic resin to bond the adherends together.

[0052] For example, a first embodiment of a method for using a thermoplastic adhesive sheet will be described with reference to Figures 1A and 1B, which show schematic cross-sectional views. Figure 1A shows a state before bonding, in which a thermoplastic adhesive sheet 11 is interposed between sheet-shaped adherends 12 and 12'. Figure 1B shows a state in which the adherends 12 and 12' have been bonded together via the thermoplastic adhesive sheet 11.

[0053] In Figure 1A, adherend 12, thermoplastic adhesive sheet 11, and adherend 12' are stacked in this order, and pressure is applied from one adherend 12 side in the stacking direction (the direction of the arrow in Figure 1A) while heating to above the softening point of the thermoplastic resin in thermoplastic adhesive sheet 11. Heating to above the softening point of the thermoplastic resin softens the thermoplastic resin, allowing adhesion between adherend 12 and thermoplastic adhesive sheet 11, which are pressed together under pressure, and between thermoplastic adhesive sheet 11 and adherend 12'. This not only allows adhesion between adherends 12 and 12', but also ensures insulation by preventing contact between adherends 12 and 12' due to the presence of thermoplastic adhesive sheet 11.

[0054] The adherends 12, 12' may be bonded to the thermoplastic adhesive sheet 11 at the same time, or the adherend 12 and the thermoplastic adhesive sheet 11 may be bonded together by heating and pressurizing to form an adhesive structure, and then the adhesive structure and the adherend 12' may be bonded together by heating and pressurizing to bond the adherend 12' to the thermoplastic adhesive sheet 11.

[0055] Known methods for applying heat and pressure during bonding can be used, such as heat pressing using a heated press plate, or applying a load in a heated atmosphere such as a heating furnace, etc. Depending on the shape of the adherend 12', pressure may be applied not only from the adherend 12 side but also from the adherend 12' side simultaneously.

[0056] The heating temperature is not particularly limited as long as there are no restrictions on the heat resistance of the adherends 12, 12'. For example, based on the softening point of the thermoplastic resin, the heating temperature may be (softening point + 10)°C or higher, preferably (softening point + 30)°C or higher, and more preferably (softening point + 50)°C or higher. The upper limit of the heating temperature may be, for example, (softening point + 250)°C or lower, preferably (softening point + 200)°C or lower, and more preferably (softening point + 150)°C or lower, particularly from the viewpoint of suppressing deterioration of the thermoplastic resin.

[0057] The pressure is not particularly limited as long as it can adhere, and may be, for example, 0.001 MPa or more, preferably 0.01 MPa or more, and more preferably 0.1 MPa or more. The upper limit is not particularly limited, and may be, for example, about 20 MPa. A pressure that does not cause the thermoplastic resin to protrude from the gaps in the adherend is desirable. The time for hot pressing is also not particularly limited, and may be, for example, within 1 hour. However, since exposure to high temperatures for a long period of time may cause the thermoplastic resin to deteriorate or flow, it is preferable to perform the hot pressing for a relatively short period of time, for example, within 30 minutes, preferably within 15 minutes, and more preferably within 10 minutes. The lower limit is not particularly limited, and may be, for example, about 1 minute.

[0058] Alternatively, one adherend may have a hole formed therein, and a thermoplastic adhesive sheet may be used to secure another adherend to that hole. For example, a second embodiment of a method for using a thermoplastic adhesive sheet will be described with reference to FIGS. 2A and 2B, which show schematic cross-sectional views. FIG. 2A shows the state before bonding, in which a thermoplastic adhesive sheet 21 and an adherend 22 are inserted into a hole 23 in an adherend 22', with the thermoplastic adhesive sheet 21 interposed between the adherends 22 and 22'. FIG. 2B shows the state in which the adherends 22 and 22' are bonded to each other via the thermoplastic adhesive sheet 21, with the adherend 22 secured in the hole 23 in the adherend 22'. In FIG. 2A, the hole 23 is formed as an entirely enclosed space, but it does not need to be an entirely enclosed closed space; for example, it may have an open space formed in part, such as a U-shape. Note that FIG. 2A also shows a portion of the adherend 22'.

[0059] In Figure 2A, thermoplastic adhesive sheet 21 and adherend 22 are inserted into hole 23 in adherend 22', and the thermoplastic adhesive sheet 21 is laminated so that it contacts the surface of adherend 22' that forms hole 23 and adherend 22. Pressure is applied from the adherend 22 side in the lamination direction (the direction of the arrow in Figure 2A) while the sheet is heated to above the softening point of the thermoplastic resin in thermoplastic adhesive sheet 21. Heating to above the softening point of the thermoplastic resin softens the thermoplastic resin, allowing adhesion between adherend 22 and thermoplastic adhesive sheet 21, which are pressed together under pressure, and between thermoplastic adhesive sheet 21 and adherend 22'. This fixes adherend 22 in hole 23 in adherend 22', and the presence of thermoplastic adhesive sheet 21 prevents contact between adherends 22 and 22', thereby ensuring insulation.

[0060] When inserting the thermoplastic adhesive sheet 21 and the adherend 22 into the hole 23 of the adherend 22′, the thermoplastic adhesive sheet 21 and the adherend 22 may be inserted separately or simultaneously in an unglued state, or they may be inserted as an adhesive structure in which the thermoplastic adhesive sheet 21 and the adherend 22 are adhered. When the hole 23 is a narrow portion, it is preferable that the thermoplastic adhesive sheet 21 and the adherend 22 are an integrated adhesive structure.

[0061] One or more thermoplastic adhesive sheets 21 may be used, but when the hole 23 is a narrow portion, it is preferable to interpose one thermoplastic adhesive sheet 21 between the adherends 22, 22'.

[0062] One method of applying pressure is to apply a load from the adherend 22 side. In particular, when the hole 23 is a narrow portion, an expandable sheet may be inserted between the side of the adherend 22 opposite the thermoplastic adhesive sheet 21 and the surface of the adherend 22' where the hole 23 is formed, and pressure may be applied by the stress caused by expansion. Examples of expandable sheets include composite sheets made of reinforcing fibers and resin, which expand due to the repulsive force generated by the reinforcing fibers when the resin is softened by heating. Such expandable sheets that expand when heated are preferably used because they can expand and apply pressure simultaneously with the thermoplastic adhesive sheet being bonded by heating.

[0063] Thermoplastic adhesive sheets can be suitably used as insulating adhesives that can insulate and bond adherends together in transportation means, home appliances, industrial machinery, buildings, etc. Depending on the type of thermoplastic resin and insulating reinforcing fiber sheet, the thermoplastic adhesive sheet can also have heat resistance, making it suitable for use as a heat-resistant adhesive.

[0064] For example, in a motor (e.g., a motor for driving an automobile), by using it as a fixing material for adhesively fixing permanent magnets in a plurality of holes or recesses formed in a rotor or stator, it is possible to fix the permanent magnets with sufficient adhesive strength and also to impart insulating properties.

[0065] For example, motors that use permanent magnets in the rotor include interior permanent magnet motors (IPM motors) and surface permanent magnet motors (SPM motors). In SPM motors, permanent magnets are fixed in recesses on the rotor surface, while in IPM motors, permanent magnets are fixed in holes on the rotor. Because thermoplastic adhesive sheets have excellent adhesive properties, they are more suitable for use in IPM motors, which are useful for high-speed rotation.

[0066] The present invention will be described in more detail below with reference to examples, but the present invention is not limited by these examples. In the following examples and comparative examples, various physical properties were measured by the following methods.

[0067] [Glass Transition Temperature (Tg) of Thermoplastic Resin] The glass transition temperature of a thermoplastic resin was determined from the peak temperature obtained by measuring the temperature dependence of loss tangent (tan δ) at a frequency of 10 Hz and a heating rate of 10°C / min using a solid state dynamic viscoelasticity analyzer "Rheospectra DVE-V4" manufactured by Rheology Corp. Here, the peak temperature of tan δ refers to the temperature at which the first derivative of the change in tan δ with respect to temperature becomes zero.

[0068] [Basis Weight of Thermoplastic Resin Sheet and Insulating Reinforced Fiber Sheet] A sample of a thermoplastic resin sheet and an insulating reinforcing fiber sheet, each measuring 250 mm in length and 250 mm in width, was cut into 80 small pieces measuring 50 mm in length and 15 mm in width, and the weight (g) of each small piece was measured. ２ ) was calculated, and the average value of the basis weight of all the small pieces was used as the basis weight (g / m ２ )

[0069] [Thickness of insulating reinforcing fiber sheet] A sample of an insulating reinforcing fiber sheet measuring 250 mm in length and 250 mm in width was cut into 80 small pieces measuring 50 mm in length and 15 mm in width, and the central thickness (μm) of each small piece was measured using a high-precision digimatic micrometer “MDH-25MB” manufactured by Mitutoyo Corporation. The average thickness of all the small pieces was taken as the thickness (μm) of the insulating reinforcing fiber sheet.

[0070] [Density of Thermoplastic Resin and Insulating Reinforcing Fiber] The density of the thermoplastic resin and insulating reinforcing fiber was determined by measuring the density of each sample in a 25°C environment by the underwater displacement method using a hydrometer "ELECTRONIC DENSIMETER SD-200L" manufactured by Alpha Mirage Co., Ltd. Measurement was repeated five times for a 10 g sample, and the average value was calculated as the density (g / cm) of each sample. ３ )

[0071] [Volume Ratio of Insulating Reinforcing Fiber Sheet] The volume ratio of the insulating reinforcing fiber sheet to the total volume of the thermoplastic resin constituting the thermoplastic adhesive sheet and the insulating reinforcing fiber sheet was calculated by converting the weight ratio using the respective densities.

[0072] [Theoretical Thickness of Thermoplastic Adhesive Sheet] The theoretical thickness (μm) of the thermoplastic adhesive sheet was calculated from the basis weight (weight per unit area) of the insulating reinforcing fiber sheet, the volume ratio of the insulating reinforcing fiber sheet, and the density of the insulating reinforcing fibers measured above using the following formula: T = Mp / σp + Mf / σf (where T: theoretical thickness [μm], Mp: weight per unit area of ​​thermoplastic resin [g / m ２ ], σp: density of thermoplastic resin [g / cm ３ ], Mf: weight per unit area of ​​insulating reinforcing fiber sheet [g / m ２ ], σf: density of insulating reinforcing fiber [g / cm３ ])

[0073] [Exposure rate of insulating reinforcing fiber sheet] Using a laser microscope (Keyence Corporation "VK-X3000"), 20 planar images of each thermoplastic adhesive sheet sample were taken at 10x magnification, at different locations on the front and back surfaces. Using the binarization function of the image analysis software "ImageJ," the proportion of the area occupied by the insulating reinforcing fiber portion to the total area in the surface image of each surface was measured, and the average value of the 20 sheets was used as the exposure rate.

[0074] [Shear Adhesion Strength] The shear adhesive strength of the thermoplastic adhesive sheet to an iron test piece was measured with reference to JIS K 6850 "Test method for tensile shear adhesive strength of adhesives - rigid adherends." Two iron test pieces (SPCC-SD, manufactured by Standard Test Piece Co., Ltd.; thickness 1.6 mm, length 100 mm, width 25 mm) were prepared, and a thermoplastic adhesive sheet cut to a length of 10 mm and a width of 25 mm was placed in a region 10 mm long and 25 mm wide at the end of the longitudinal direction of one of the iron test pieces. The thermoplastic adhesive sheet was then pressed using a test press (Kitagawa Seiki Co., Ltd.'s "KVHC-II") at a predetermined temperature, 2 MPa, and for 1 minute to bond the iron test piece to one side of the thermoplastic adhesive sheet. Then, a 10 mm, 25 mm wide area of ​​the other iron test piece was placed on the other side of the thermoplastic adhesive sheet at the longitudinal end, and the other iron test piece was held in a hot air oven at a predetermined temperature for 10 minutes under a load of 0.04 MPa to prepare a sample for shear bond strength measurement. Each iron test piece obtained for shear bond strength measurement was gripped and pulled at a tensile speed of 1 mm / min using a tensile tester (Shimadzu Corporation, "AG-5000B"), and the shear bond strength (MPa) was measured from the load at break. The measurement was performed five times, and the average value was calculated.

[0075] [Insulation] Before measuring the shear bond strength of the above-mentioned shear bond strength measurement sample, the needle of a tester ("HiTESTER 3244-60" manufactured by Hioki E.E. Corporation) was brought into contact with the center of the width direction of the upper and lower iron test pieces, at a position 10 mm from the end in the length direction, to measure the resistance value. If the resistance value was equal to or higher than the upper limit of detection (42 MΩ), the insulation was evaluated as A, and if a resistance value was detected, the insulation was evaluated as B.

[0076] [Warpage] The thermoplastic adhesive sheet obtained was visually inspected and rated as A if there was no warpage, B if there was slight warpage, and C if there was significant warpage.

[0077] [Scratch Load] Using a load-varying friction and wear test system (manufactured by Shinto Scientific Co., Ltd., "Tribogear HHS2000"), the surface of the thermoplastic adhesive sheet was scratched with a 0.1 mm radius sapphire scratching needle at a speed of 1 mm / s and a load of 0 to 500 g, while continuously increasing the load, and the load (g) at which the thermoplastic adhesive sheet began to break was measured. Here, the load at which the thermoplastic adhesive sheet began to break was the load at which damage to the insulating reinforcing fibers of the thermoplastic adhesive sheet was observed. The measurement was performed three times, and the average value was calculated.

[0078] Example 1 A polyetherimide (hereinafter sometimes abbreviated as PEI) polymer ("ULTEM 9001" manufactured by Servic Innovative Plastics) which is an amorphous thermoplastic resin was vacuum dried for 12 hours at 150° C. The PEI polymer was extruded using an extruder and fed to a meltblown nonwoven fabric production apparatus equipped with a nozzle having a nozzle hole diameter D (diameter) of 0.4 mm, L (nozzle length) / D = 7.5, and a nozzle hole pitch of 0.68 mm. The extrusion rate per hole was 0.2 g / min, the spinning temperature was 430° C., the hot air temperature was 450° C., and the nozzle width was 10 Nm per 1 m. ３ The meltblown nonwoven fabric thus obtained had a basis weight of 35 g / m. ２ The glass transition temperature (softening point of the amorphous thermoplastic resin) is 217°C, and the density is 1.27 g / cm ３ It was.

[0079] The thermoplastic resin sheet was a PEI meltblown nonwoven fabric, and the insulating reinforcing fiber sheet was a glass cloth (basis weight 12 g / m ２ , thickness 0.015 mm, glass fiber density 2.54 g / cm ３ ) and laminated in the following order: PEI meltblown nonwoven fabric / glass cloth / PEI meltblown nonwoven fabric. Using a test press machine (Kitagawa Seiki Co., Ltd., "KVHC-II"), the laminate was heat-pressed at 300°C and 2 MPa in the lamination direction for 1 minute, allowing the molten PEI polymer to penetrate between the glass fibers, producing a thermoplastic adhesive sheet. The resulting thermoplastic adhesive sheet showed no warping.

[0080] The obtained thermoplastic adhesive sheet was subjected to various evaluations, and the evaluation results are shown in Table 1. When preparing samples for measuring shear adhesive strength, the set temperature of the test press was 300°C, and the set temperature of the hot air oven was 320°C.

[0081] [Example 2] A glass cloth ("H25X104HE" manufactured by Unitika Ltd.; basis weight 24.5 g / m) was used as an insulating reinforcing fiber sheet. ２ , thickness 0.03 mm, glass fiber density 2.54 g / cm ３ A thermoplastic adhesive sheet was produced in the same manner as in Example 1, except that the thermoplastic adhesive sheet was made of a cellulose acylate copolymer, and various evaluations were carried out. The obtained thermoplastic adhesive sheet showed no warping.

[0082] [Example 3] A thermoplastic adhesive sheet was produced and various evaluations were carried out in the same manner as in Example 1, except that three sheets of the glass cloth used in Example 2 were stacked together as the insulating reinforcing fiber sheet. The obtained thermoplastic adhesive sheet showed no warping.

[0083] [Example 4] In the production of a meltblown nonwoven fabric, the basis weight of the resulting PEI meltblown nonwoven fabric was 25 g / m ２ A PEI meltblown nonwoven fabric was obtained in the same manner as in Example 1, except that the obtained PEI meltblown nonwoven fabric was used as the thermoplastic resin sheet and three layers of the glass cloth used in Example 2 were used as the insulating reinforcing fiber sheet, and a thermoplastic adhesive sheet was produced and subjected to various evaluations in the same manner as in Example 1. The obtained thermoplastic adhesive sheet showed no warping.

[0084] Example 5 A crystalline thermoplastic resin, polyether ether ketone (hereinafter sometimes abbreviated as PEEK), based polymer ("90G" manufactured by Victrex) was vacuum dried at 80°C for 12 hours. 0.35 g of the PEEK based polymer was placed inside a metal frame with inner dimensions of 100 mm x 100 mm x 25 μm thick, which was placed on a polyimide film, and pressed using a test press ("KVHC-II" manufactured by Kitagawa Seiki Co., Ltd.) under conditions of 380°C, 2 MPa, and 1 minute to obtain a film. The obtained film had a basis weight of 33 g / m. ２ The melting point (softening point of crystalline thermoplastic resin) is 343°C, and the density is 1.30 g / cm ３ A thermoplastic adhesive sheet was produced in the same manner as in Example 1, except that the obtained PEEK film was used as the thermoplastic resin sheet and the glass cloth used in Example 2 was used as the insulating reinforcing fiber sheet, and various evaluations were performed. The obtained thermoplastic adhesive sheet showed no warping. When producing samples for measuring shear bond strength, the set temperature of the test press was 380°C, and the set temperature of the hot air oven was 380°C.

[0085] Example 6 A phenoxy polymer (Yp50s manufactured by Nippon Steel Chemical & Material Co., Ltd.), which is an amorphous thermoplastic resin, was vacuum dried for 12 hours at 60° C. The phenoxy polymer was extruded using an extruder and fed to a meltblown nonwoven fabric production apparatus equipped with a nozzle having a nozzle hole diameter D (diameter) of 0.3 mm, L (nozzle length) / D=7.5, and a nozzle hole pitch of 0.68 mm. The extrusion rate per hole was 0.2 g / min, the spinning temperature was 350° C., the hot air temperature was 360° C., and the nozzle width was 10 Nm per 1 m. ３ The meltblown nonwoven fabric thus obtained had a basis weight of 30 g / m. ２ The glass transition temperature (softening point of the amorphous thermoplastic resin) is 84°C, and the density is 1.17 g / cm ３ It was.

[0086] The phenoxy melt-blown nonwoven fabric obtained as a thermoplastic resin sheet and the glass cloth used in Example 2 as an insulating reinforcing fiber sheet were laminated in the following order: phenoxy melt-blown nonwoven fabric / glass cloth / phenoxy melt-blown nonwoven fabric. Using a test press (Kitagawa Seiki Co., Ltd., "KVHC-II"), the laminate was heat-pressed at 200°C and 2 MPa in the lamination direction for 1 minute, allowing the molten phenoxy polymer to impregnate the spaces between the glass fibers, producing a thermoplastic adhesive sheet. The resulting thermoplastic adhesive sheet showed no warping. The test press temperature was set to 200°C, and the hot air oven temperature was set to 220°C when preparing the sample for shear bond strength measurement.

[0087] Example 7 A thermoplastic adhesive sheet was produced and evaluated in the same manner as in Example 1, except that the PEI meltblown nonwoven fabric obtained in Example 1 was used as the thermoplastic resin sheet, the glass cloth used in Example 2 was used as the insulating reinforcing fiber sheet, and the layers were laminated in the order of two PEI meltblown nonwoven fabrics per glass cloth. The resulting thermoplastic adhesive sheet was significantly warped.

[0088] Example 8 A thermoplastic adhesive sheet was produced and subjected to various evaluations in the same manner as in Example 1, except that the PEI meltblown nonwoven fabric obtained in Example 1 was used as the thermoplastic resin sheet, the glass cloth used in Example 2 was used as the insulating reinforcing fiber sheet, and the sheets were laminated in the following order: 2 sheets of PEI meltblown nonwoven fabric / 3 sheets of glass cloth. The resulting thermoplastic adhesive sheet was slightly warped.

[0089] [Example 9] A thermoplastic adhesive sheet was produced and various evaluations were carried out in the same manner as in Example 1, except that two sheets of the glass cloth used in Example 2 were stacked together as the insulating reinforcing fiber sheet. The obtained thermoplastic adhesive sheet showed no warping.

[0090] Example 10 A thermoplastic adhesive sheet was produced in the same manner as in Example 1, except that the PEI meltblown nonwoven fabric obtained in Example 1 was used as the thermoplastic resin sheet, and the glass cloth used in Example 2 was used as the insulating reinforcing fiber sheet, and the sheets were laminated in the following order: 1 glass cloth / 2 PEI meltblown nonwoven fabrics / 1 glass cloth. The resulting thermoplastic adhesive sheet showed no warping.

[0091] [Comparative Example 1] A thermoplastic adhesive sheet was produced and subjected to various evaluations in the same manner as in Example 1, except that the PEI meltblown nonwoven fabric obtained in Example 4 was used as the thermoplastic resin sheet and five sheets of the glass cloth used in Example 2 were used as the insulating reinforcing fiber sheet. The obtained thermoplastic adhesive sheet showed no warping.

[0092] [Comparative Example 2] A thermoplastic adhesive sheet was produced and various evaluations were carried out in the same manner as in Example 1, except that no glass cloth was used. The obtained thermoplastic adhesive sheet showed no warping.

[0093] Comparative Example 3 A thermoplastic adhesive sheet was produced in the same manner as in Example 1, except that the PEI meltblown nonwoven fabric obtained in Example 4 was used as the thermoplastic resin sheet, and the glass cloth used in Example 2 was used as the insulating reinforcing fiber sheet, and the sheets were laminated in the following order: 2 sheets of PEI meltblown nonwoven fabric per 5 sheets of glass cloth. The resulting thermoplastic adhesive sheet showed no warping.

[0094]

[0095] As shown in Table 1, the thermoplastic adhesive sheets of Examples 1 to 10 bonded iron test pieces together, exhibiting high shear bond strength and ensuring insulation. In particular, the thermoplastic adhesive sheets of Examples 1 to 6 and 9 were able to reduce the exposure rate of the insulating reinforcing fiber sheet on both sides, resulting in no warping. Furthermore, the thermoplastic adhesive sheets of Examples 2, 4, and 9 had high damage loads and were excellent for insertion into narrow spaces.

[0096] On the other hand, the thermoplastic adhesive sheets of Comparative Examples 1 and 3 have a volume ratio of the insulating reinforcing fiber sheet that is too large, so their shear bond strength is smaller than that of Examples 1 to 10, and they are unable to exhibit sufficient adhesiveness.

[0097] The thermoplastic adhesive sheet of Comparative Example 2 does not contain an insulating reinforcing fiber sheet, and therefore is unable to prevent contact between the iron test pieces, and is therefore unable to ensure insulation.

[0098] Thermoplastic adhesive sheets are useful for insulating and adhering materials to each other in transportation means, home appliances, industrial machinery, buildings, etc. For example, thermoplastic adhesive sheets can be used as fixing materials for adhesively fixing permanent magnets in multiple holes formed in the rotor or stator of a motor.

[0099] While the preferred embodiments of the present invention have been described above with reference to the drawings, those skilled in the art will readily recognize various changes and modifications within the scope of the present invention upon reading the specification. Accordingly, such changes and modifications are to be interpreted as falling within the scope of the invention as defined by the claims.

[0100] 11, 21... Thermoplastic adhesive sheet 12, 12', 22, 22'... Adherent material 23... Hole

Claims

1. A thermoplastic adhesive sheet comprising a thermoplastic resin and an insulating reinforcing fiber sheet, having an adhesive surface adhered by the thermoplastic resin, wherein the volume ratio of the insulating reinforcing fiber sheet in the total volume of the thermoplastic resin and the insulating reinforcing fiber sheet is 2 to 50 vol%.

2. The thermoplastic adhesive sheet according to claim 1, wherein both surfaces of the thermoplastic adhesive sheet are adhesive surfaces, and the exposure rate of the insulating reinforcing fiber sheet on each of the adhesive surfaces is less than 10%.

3. The thermoplastic adhesive sheet according to claim 1 or 2, wherein the insulating reinforcing fiber sheet is a glass fiber fabric.

4. The thermoplastic adhesive sheet according to claim 1 or 2, wherein the thickness of the insulating reinforcing fiber sheet is 10 to 150 μm.

5. The thermoplastic adhesive sheet according to claim 1 or 2, wherein the weight Mf per unit area of the insulating reinforcing fiber sheet is 10 to 79 g / m ２ and the theoretical thickness T represented by the following formula (1) is 20 to 150 μm. Thermoplastic adhesive sheet. T = Mp / σp + Mf / σf (1) (In the formula, T: theoretical thickness [μm], Mp: weight per unit area of the thermoplastic resin [g / m ２ , σp: density of the thermoplastic resin [g / cm ３ , Mf: weight per unit area of the insulating reinforcing fiber sheet [g / m ２ , σf: density of the insulating reinforcing fiber [g / cm ３ ) 6. The thermoplastic adhesive sheet according to claim 1 or 2, wherein the glass transition temperature of the thermoplastic resin is 100°C or higher.

7. The thermoplastic adhesive sheet according to claim 1 or 2, wherein the thermoplastic resin is an amorphous thermoplastic resin.

8. The thermoplastic adhesive sheet according to claim 1 or 2, wherein the thermoplastic resin is at least one thermoplastic resin selected from the group consisting of polyetherimide resins, polyetheretherketone resins, phenoxy resins, and polycarbonate resins.

9. An adhesive structure comprising the thermoplastic adhesive sheet according to claim 1 or 2 and an adherend integrally contacted with at least a part of its adhesive surface.

10. A method of using the thermoplastic adhesive sheet according to claim 1 or 2, wherein the thermoplastic adhesive sheet is interposed between adherends, and the adherends are adhered to each other by heating at a temperature equal to or higher than the softening point of the thermoplastic resin while applying pressure in the lamination direction of the thermoplastic adhesive sheet from at least one of the adherends.

11. The method of use according to claim 10, wherein one thermoplastic adhesive sheet is interposed between the adherends.

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