Thermoplastic adhesive sheet, method of use thereof, 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

Related applications

[0001] This application claims priority to Japanese Patent Application No. 2024-008301, filed in Japan on 23 January 2024, which is incorporated herein by reference as forming part of this application. [Technical Field]

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

[0003] Conventionally, motors with permanent magnets in the rotor and stator have been used. The permanent magnets are inserted into the holes in these components, and the gaps are filled with a thermosetting resin such as epoxy resin, which is then cured to bond and fix them in place. However, when using thermosetting resins, a long curing time is required to increase the shear bond strength, which increases the cycle time during manufacturing. Furthermore, it is not possible to prevent contact between the rotor / stator and the permanent magnets, and insulating treatment must be applied to the permanent magnets to ensure insulation (electrical insulation).

[0004] Therefore, in recent years, sheet-like composite materials containing insulating reinforcing fibers and thermoplastic resins have been proposed as fixing materials. For example, Patent Document 1 (International Publication No. 2020 / 183945) discloses a space-filling material composed of reinforcing fibers as an expansive material and a resin, wherein the reinforcing fibers have multiple intersections, and at least some of these intersections are bonded with the resin, and which fills a predetermined space at least in the thickness direction due to expansion stress when heated, and which is described as being used as a molding material for fixing permanent magnets.

[0005] Furthermore, regarding sheet-like composite materials containing insulating reinforcing fibers and thermoplastic resins, for example, Patent Document 2 (International Publication No. 2018 / 150978) describes a resin-attached reinforced fiber fabric in which a thermoplastic resin is attached to at least one surface of a reinforced fiber fabric, wherein the mass W per unit area of ​​the reinforced fiber fabric is 25 g / m². 2 More than 400g / m 2 The following ranges apply, and the air permeability P of the reinforced fiber fabric is 0.1 cm 3 / cm 2 / s or more 300cm 3 / cm 2 A resin-adhered reinforced fiber fabric is disclosed, wherein the melting point of the thermoplastic resin is in the range of 70°C to 300°C, the proportion of the mass of the reinforced fiber fabric to the total mass of the resin-adhered reinforced fiber fabric is in the range of 20% to 90% by mass, the coverage rate C of the surface of the reinforced fiber fabric by the thermoplastic resin is in the range of 30% to less than 100%, and the resin adhesion coefficient A is in the range of 35 to 135.

[0006] Patent Document 3 (Japanese Patent Publication No. Hei 8-207200) describes a thermoplastic resin composite material in which a thermoplastic resin is impregnated and integrated into multiple laminated glass fiber fabrics, wherein the volume % of glass fibers is 50±5%, and the mass of the glass fiber fabric laminated on the surface is 105±2 g / m². 2 A fiber-reinforced thermoplastic resin composite material is disclosed, characterized in that the warp / weft mass ratio is in the range of 1 ± 0.05.

[0007] Patent Document 4 (Japanese Patent Publication No. 8-11133) discloses a moldable sheet material which is a laminate made by impregnating 2 to 24 mechanically cleaned glass fabrics and thermoplastic engineering plastic, wherein the volume of glass fibers is 40-60% and the thickness is 0.7-4 mm. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] International Publication No. 2020 / 183945 [Patent Document 2] International Publication No. 2018 / 150978 [Patent Document 3] Japanese Patent Application Laid-Open No. 8-207200 [Patent Document 4] Japanese Patent Application Laid-Open No. 8-11133 [Summary of the Invention] [Problems to be Solved by the Invention]

[0009] However, in recent years, the demand for high-speed motors used in electric vehicles and the like has been expanding. In the case of such high-speed motors, the method of fixing permanent magnets by pressing with expansion stress like the space filler described in Patent Document 1 has insufficient fixing force.

[0010] Moreover, Patent Documents 2 to 4 only describe sheet-like composite materials used for manufacturing molded products, and do not describe the use of adhering adherends such as permanent magnets.

[0011] Therefore, an object of the present invention is to provide a thermoplastic adhesive sheet exhibiting high insulation and shear adhesion strength. [Means for Solving the Problems]

[0012] As a result of intensive studies to solve the above problems, the present inventors have found that in a thermoplastic adhesive sheet having an adhesive surface adhered by a thermoplastic resin, by containing an insulation reinforcing fiber sheet at a specific volume ratio, it adheres to an adherend and exhibits high shear adhesion strength, and at the same time, contact can be suppressed as an insulating material of the adherend to ensure insulation, and thus the present invention has been completed.

[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, and 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% (preferably 5 to 48 vol%, more preferably 10 to 45 vol%, still more preferably 13 to 40 vol%). [Aspect 2] The thermoplastic adhesive sheet according to Aspect 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% (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 thickness of the insulating reinforcing fiber sheet is 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 Mf per unit area of the insulating reinforcing fiber sheet is 10 to 79 g / m 2 (preferably 12 to 75 g / m 2 , 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) (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 ) [Aspect 6] A thermoplastic adhesive sheet according to any one of embodiments 1 to 5, wherein the glass transition temperature of the thermoplastic resin is 100°C or higher (preferably 120°C or higher, more preferably 150°C or higher). [Aspect 7] A thermoplastic adhesive sheet according to any one of embodiments 1 to 6, wherein the thermoplastic resin is an amorphous thermoplastic resin. [Aspect 8] A thermoplastic adhesive sheet according to any one embodiment of embodiments 1 to 7, 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. [Aspect 9] An adhesive structure comprising a thermoplastic adhesive sheet according to any one of embodiments 1 to 8, and a workpiece integrated with at least a portion of the adhesive surface thereof. [Aspect 10] A method of using a thermoplastic adhesive sheet according to any one of embodiments 1 to 8, wherein the thermoplastic adhesive sheet is interposed between adherends, and the adherends are bonded together by heating the sheet at a temperature above 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. [Aspect 11] A method of use according to embodiment 10, wherein one 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 form, including “at least one,” unless the context explicitly indicates otherwise. As used herein, the terms “and / or,” “at least one,” and “one or more” include any and all combinations of the related enumerated items.

[0015] Furthermore, any combination of at least two components disclosed in the claims and / or the specification and / or drawings is included in the present invention. In particular, any combination of two or more claims described in the claims is included in the present invention. [Effects of the Invention]

[0016] According to the thermoplastic adhesive sheet of the present invention, it can adhere to a substrate, exhibit high shear adhesive strength, and ensure the insulating properties of the substrate. [Brief explanation of the drawing]

[0017] This invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. The drawings are not necessarily shown to a constant scale and are exaggerated in order to illustrate the principles of the present invention. However, the embodiments and drawings are for illustrative and explanatory purposes only and should not be used to define the scope of this invention. The scope of this invention is defined by the appended claims. [Figure 1A] This is a schematic cross-sectional view of the first embodiment of a method for using a thermoplastic adhesive sheet, showing the state before bonding. [Figure 1B] This 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 2A] This is a schematic cross-sectional view of a second embodiment of the method for using a thermoplastic adhesive sheet, showing the state before bonding. [Figure 2B] This is a schematic cross-sectional view of a second embodiment of the method for using a thermoplastic adhesive sheet, showing the state after bonding. [Modes for carrying out the invention]

[0018] <Thermoplastic adhesive sheet> A thermoplastic adhesive sheet comprises a thermoplastic resin and an insulating reinforcing fiber sheet, and has an adhesive surface bonded by the thermoplastic resin. The thermoplastic adhesive sheet can bond the adherends in contact with the adhesive surface by heating, as the thermoplastic resin softens. The adhesive surface refers to the surface mainly composed of the thermoplastic resin, and may be, for example, a surface where 50% or more of the total area of ​​the thermoplastic adhesive sheet in a plan view is composed of the thermoplastic resin. Even if only one side of the thermoplastic adhesive sheet is the adhesive surface, depending on the form of the thermoplastic resin and insulating reinforcing fiber sheet, the bonding conditions, etc., the thermoplastic resin may flow to the other side (non-adhesive surface) and bond the adherends in contact with the non-adhesive surface.

[0019] Thermoplastic adhesive sheets have a volume ratio of insulating reinforcing fiber sheet to the total volume of thermoplastic resin and insulating reinforcing fiber sheet of 2 to 50 vol%. By including insulating reinforcing fiber sheet in 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. As a result, when a substrate is bonded to the thermoplastic adhesive sheet, it can adhere to the substrate and exhibit high shear adhesive strength. Furthermore, it acts as an insulating material for the substrate, and the insulating reinforcing fiber sheet can suppress contact with the substrate, thereby ensuring insulation. If the volume ratio of insulating reinforcing fiber sheet is too small, the shape retention of the insulating reinforcing fiber sheet may be insufficient, and the thermoplastic resin may squeeze out from the bonding surface during bonding, potentially contaminating the substrate. Moreover, it may not be possible to prevent contact with the substrate, and insulation may not be ensured. On the other hand, if the volume ratio of insulating reinforcing fiber sheet is too large, the contact area between the thermoplastic resin and the substrate may be insufficient, resulting in low shear adhesive strength when bonded to the substrate and insufficient adhesion. The volume ratio of the insulating reinforcing fiber sheet to the total volume of the thermoplastic resin and the insulating reinforcing fiber sheet may preferably be 5 to 48 vol%, more preferably 10 to 45 vol%, and even more preferably 13 to 40 vol%.

[0020] Thermoplastic resins include, for example, vinyl resins (polymers or derivatives thereof synthesized from monomers having vinyl groups CH2=CH- or vinylidene groups CH2=C<; for example, polyolefin resins such as polyethylene and polypropylene; acrylic resins such as polymethyl methacrylate; polyvinyl chloride resins; polystyrene resins, etc.); aliphatic polyamide resins (polyamide 6, polyamide 66, polyamide 11, polyamide 12, polyamide 610, polyamide 612, etc.), semi-aromatic polyamide resins, fully aromatic polyamide resins, and other polyamide resins; polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene Examples include polyester resins such as rennaphthalate; fluororesins such as polytetrafluoroethylene resins; thermoplastic polyimide resins such as semi-aromatic polyimide resins, polyamide-imide resins, and polyetherimide resins; polysulfone resins such as polysulfone resins and polyethersulfone resins; polyphenylene sulfide resins; modified polyphenylene ether resins; polyetherketone resins such as polyetherketone resins, polyetheretherketone resins, and polyetherketoneketone resins; phenoxy resins; polycarbonate resins; amorphous polyarylate resins; and liquid crystal polyester resins such as fully aromatic polyester resins. These thermoplastic resins may be used individually or in combination of two or more types.

[0021] Furthermore, for applications requiring heat resistance, it is preferable to use a thermoplastic resin with 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, polyetherketone 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 adhesion, it is preferable to use amorphous thermoplastic resins. 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 cannot be clearly identified, it may be considered substantially amorphous.

[0023] Of the above thermoplastic resins, it is preferable that at least one thermoplastic resin selected from the group consisting of polyetherimide resins, polyetheretherketone resins, phenoxy resins, and polycarbonate resins is used, from the viewpoint of heat resistance and adhesion. From the viewpoint of heat resistance and adhesion when the adherend is a metal material, polyetherimide resins are more preferable.

[0024] The thermoplastic resin may contain various additives, as long as they do not impair the effects of the present invention.

[0025] The form of the thermoplastic resin in the thermoplastic adhesive sheet is not particularly limited. For example, it may be in the form of a sheet (thermoplastic resin sheet) such as a fabric, knitted fabric, nonwoven fabric, or film, laminated with an insulating reinforced fiber sheet. In this case, the thermoplastic resin sheet may constitute the adhesive surface. Furthermore, for applications where the sheet is inserted into a narrow space for bonding, the insulating reinforced fiber sheet may be impregnated with at least a portion of the thermoplastic resin as a matrix resin. For example, the thermoplastic adhesive sheet may comprise a shape-retaining layer in which the thermoplastic resin is impregnated into the insulating reinforced fiber sheet, and an adhesive layer containing the thermoplastic resin existing as the outermost layer on at least one surface of the shape-retaining layer.

[0026] The insulating reinforced fiber sheet is composed of insulating reinforced fibers, which may be inorganic or organic fibers. 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, and examples include liquid crystal polyester fibers, all-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 also be, for example, the heat deflection temperature (JIS K 7207). In particular, in the case of amorphous thermoplastic resins, it refers to their glass transition temperature. Of these, the insulating reinforced fibers are preferably inorganic fibers from the viewpoint of excellent heat resistance. Furthermore, glass fibers are more preferable from the viewpoint of adhesion.

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

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

[0029] The insulating reinforced 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, insulation, and ease of insertion into narrow spaces. In this specification, the thickness of the insulating reinforced fiber sheet refers to the total thickness when multiple insulating reinforced fiber sheets are stacked, and is a value measured by the method described in the examples below.

[0030] The insulating reinforced fiber sheet has a weight Mf of 10-79 g / m² per unit area. 2 It may be as low as 12-75 g / m², preferably 12-75 g / m². 2 More comfortably, 15-70 g / m 2 This may also be the case. In this specification, the weight per unit area (basis weight) is the value measured by the method described in the examples below.

[0031] The insulating reinforced fiber sheet may have a known surface treatment agent applied to its surface to improve adhesion to the thermoplastic resin. For example, if the insulating reinforced fiber is an inorganic fiber (e.g., glass fiber), a silane coupling agent may be applied to the surface of the insulating reinforced fiber sheet. Known silane coupling agents can be used, such as epoxysilane, vinylsilane, aminosilane, chlorsilane, mercaptosilane, (meth)acrylicsilane, cationicsilane, and the like.

[0032] When the adherend is a metal material, a thermoplastic adhesive sheet preferably consists of a polyetherimide resin as the thermoplastic resin and a glass fiber fabric as the insulating reinforcement fiber sheet. Since the polyetherimide resin has good adhesion to metal materials as well as good adhesion to glass fibers, the shear adhesive strength can be improved when a metal material is bonded to the thermoplastic adhesive sheet.

[0033] A thermoplastic adhesive sheet may have adhesive surfaces on both sides. When both sides are adhesive surfaces, the adherends can be bonded together via the thermoplastic adhesive sheet, exhibiting high shear adhesive strength. Furthermore, the thermoplastic adhesive sheet can suppress contact between adherends, ensuring insulation. For example, a thermoplastic adhesive sheet may comprise a shape-retaining layer in which a thermoplastic resin is impregnated into an insulating reinforced fiber sheet, and an adhesive layer containing a thermoplastic resin present as the outermost layer on both sides of the shape-retaining layer.

[0034] When a thermoplastic adhesive sheet has adhesive surfaces on both sides, it is preferable, more preferably less than 10%, even more preferably 2% or less, and most preferably 0%, that the exposure rate of the insulating reinforcing fiber sheet on each adhesive surface is less than 10%, more preferably less than 5%, even more preferably 2% or less, and most preferably 0%. By reducing the exposure rate of the insulating reinforcing fiber sheet on the adhesive surface of the thermoplastic adhesive sheet, the formation of irregularities due to the surface shape of the insulating reinforcing fiber sheet can be suppressed, thereby reducing surface friction resistance and facilitating insertion into narrow spaces. Furthermore, when the volume ratio of the insulating reinforcing fiber sheet is relatively small, a high exposure rate of the insulating reinforcing fiber sheet tends to cause warping of the thermoplastic adhesive sheet. However, by reducing the exposure rate of the insulating reinforcing fiber sheet on both adhesive surfaces, warping of the thermoplastic adhesive sheet can be suppressed, improving handling. In this specification, the exposure rate of the insulating reinforcing fiber sheet indicates 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 area (for example, a gap of about 50 to 5000 μm) and accurately bonding the adherend, the theoretical thickness T represented 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) (In the formula, T: theoretical thickness [μm], Mp: weight per unit area of ​​thermoplastic resin [g / m²]) 2 ], σp: Density of thermoplastic resin [g / cm³] 3 ], Mf: Weight per unit area of ​​insulating reinforced fiber sheet [g / m 2 ], σf: Density of insulating reinforcing fibers [g / cm³] 3 ])

[0036] From the viewpoint of adhesion, thermoplastic adhesive sheets are preferably low in expansion when heated. If the expansion is high, when heated and bonded to the adherend, voids may be created within the thermoplastic adhesive sheet due to expansion, and the shear adhesive strength may decrease due to these voids. For example, the maximum expansion rate in the thickness direction of the thermoplastic adhesive sheet may be 50% or less, preferably 20% or less, more preferably 10% or less, and even more preferably 1% or less. In this specification, the maximum expansion rate in the thickness direction refers to the expansion rate when heated for 10 minutes at a temperature above the softening point of the thermoplastic resin under no pressure, and the expansion rate is determined from the thickness of the thermoplastic adhesive sheet before heating by the formula: thickness of the thermoplastic adhesive sheet after heating / thickness of the thermoplastic adhesive sheet before heating × 100.

[0037] From the viewpoint of adhesion, thermoplastic adhesive sheets preferably contain substantially no binder components that can be used in the manufacture of thermoplastic resin sheets or insulating reinforced fiber sheets. For example, the binder component content of 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 fabrics are used as a precursor and impregnated into the insulating reinforced fiber sheet by heat pressing or the like, it is preferable to use a fabric that can be formed without using a binder component (e.g., spunbond nonwoven fabric, meltblown nonwoven fabric, etc.). In addition, insulating reinforced fiber sheets may use sizing agents containing binder components in the manufacturing process, but it is preferable that they are removed by washing in a later 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 adhesive strength of 19 MPa or higher, preferably 20 MPa or higher, more preferably 23 MPa or higher, and even more preferably 25 MPa or higher, as measured by the method described in the examples below. The upper limit of the shear adhesive strength is not particularly limited, but may be, for example, 50 MPa or lower.

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

[0040] As a method for manufacturing a thermoplastic adhesive sheet, when forming a laminated sheet of a thermoplastic resin sheet and an insulating reinforced fiber sheet, methods include overlapping the thermoplastic resin sheet and the insulating reinforced fiber sheet, or coating the insulating reinforced fiber sheet with a thermoplastic resin. For example, from the viewpoint of easily adjusting the volume ratio of the insulating reinforced fiber sheet, the method for manufacturing a thermoplastic adhesive sheet may include a step of laminating the thermoplastic resin sheet and the insulating reinforced fiber sheet. The thermoplastic resin sheet may be a sheet composed of the above-mentioned thermoplastic resin, and as a sheet shape, examples include fabrics such as woven fabrics, knitted fabrics, and nonwoven fabrics, or films. From the viewpoint of not containing binder components, 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 viewpoint of uniformity, shapeability, and impregnation into the insulating reinforced fiber sheet, the thermoplastic resin sheet is more preferably a meltblown nonwoven fabric. The insulating reinforced fiber sheet may be a fiber sheet composed of the insulating reinforced fibers described above, and examples of fiber sheet shapes include woven fabrics, knitted fabrics, braided fabrics, and nonwoven fabrics. From the viewpoint of suppressing the expansion of the resulting thermoplastic adhesive sheet, the insulating reinforced fiber sheet is preferably an insulating reinforced fiber woven fabric.

[0041] The configuration of the laminated sheet of thermoplastic resin sheet and insulating reinforced fiber sheet obtained by the lamination process is not limited as long as an adhesive surface can be formed and the volume ratio of the insulating reinforced fiber sheet can be adjusted, and it may include one or more thermoplastic resin sheets and one or more insulating reinforced fiber sheets. For example, from the viewpoint of forming an adhesive surface, it is preferable to include the thermoplastic resin sheet so that it is at least one of the outermost layers. Also, from the viewpoint of forming adhesive surfaces on both sides of the thermoplastic adhesive sheet, it is preferable to include the thermoplastic resin sheet so that it is both of the outermost layers. For example, the laminated sheet of thermoplastic resin sheet and insulating reinforced fiber sheet obtained by the lamination process may be configured in the order of one or more thermoplastic adhesive sheets / one or more insulating reinforced fiber sheets / one or more thermoplastic adhesive sheets. In this case, one thermoplastic resin sheet and the other thermoplastic resin sheet may be made of the same type of thermoplastic resin or different types of thermoplastic resin, but from the viewpoint of adhesion, it is preferable that they be made of the same type of thermoplastic resin.

[0042] A thermoplastic adhesive sheet may be a laminated sheet of a thermoplastic resin sheet and an insulating reinforced 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 reinforced fiber sheet, methods for manufacturing the thermoplastic adhesive sheet include a method of hot-pressing the laminated sheet to soften and flow the thermoplastic resin sheet and impregnate it into the insulating reinforced fiber sheet, or a method of immersing the insulating reinforced fiber sheet in molten thermoplastic resin. For example, from the viewpoint of reducing the exposure rate of the insulating reinforced fiber sheet, the method for manufacturing a thermoplastic adhesive sheet may include a step of heating the laminated sheet of the thermoplastic resin sheet and the insulating reinforced fiber sheet above the softening point of the thermoplastic resin and applying pressure in the thickness direction to hot-press it. By adjusting conditions such as the volume ratio of the thermoplastic resin sheet and the insulating reinforced fiber sheet, the lamination configuration of the laminated sheet, and the temperature, pressure, and time of the hot press, an adhesive surface composed of a thermoplastic resin matrix with a reduced exposure rate of the insulating reinforced fiber sheet can be formed.

[0043] The heating temperature in a hot press should be set according to the softening point or decomposition temperature of the thermoplastic resin used, and it is preferable that the temperature be above the softening point of the thermoplastic resin. For example, if the thermoplastic resin is crystalline, the heating temperature is preferably in the range of above the melting point of the thermoplastic resin and below (melting point + 100)°C. If the thermoplastic resin is amorphous, the heating temperature is preferably in the range of above the glass transition temperature of the thermoplastic resin and below (glass transition temperature + 200)°C.

[0044] Furthermore, there are no particular restrictions on the pressure used during hot pressing; for example, it may be 0.01 MPa or higher, preferably 1 MPa or higher, and more preferably 5 MPa or higher. There is no particular upper limit, but for example, it may be around 20 MPa. There are no particular restrictions on the time used during hot pressing, but since prolonged exposure to high temperatures may cause the thermoplastic resin to deteriorate or flow, it is preferable to perform the process for a relatively short time, for example, it may be within 10 minutes, preferably within 1 minute, and more preferably within 30 seconds. There is no particular lower limit, but for example, it may be around 0.1 seconds.

[0045] <Adherent material> The adherend is not particularly limited as long as its softening temperature is 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 bonding, the adherend may be an inorganic material, and more preferably a metallic material.

[0046] <Adhesive structure> The adhesive structure may comprise a thermoplastic adhesive sheet and an adherend integrated with at least a portion of its adhesive surface. The adhesive structure allows the thermoplastic adhesive sheet and the adherend to be treated as a single unit, and the adherend can be used to bond to another adherend. For example, the adherend can be bonded and fixed to a narrow space by being inserted as a single unit.

[0047] An adhesive structure can be manufactured, for example, by bringing an adherend into contact with at least a portion of the adhesive surface of a thermoplastic adhesive sheet and heating it to a temperature above the softening point of the thermoplastic resin to soften the thermoplastic resin and adhere the adherend. Alternatively, an adhesive structure can be manufactured by laminating a thermoplastic resin sheet and an insulating reinforcing fiber sheet so that the thermoplastic resin sheet and the adherend are in contact, and then heating it to a temperature above the softening point of the thermoplastic resin to soften the thermoplastic resin, adhere the adherend, and impregnate the insulating reinforcing fiber sheet. When adhering adherends, the adherends may also be bonded by heating while applying pressure in the direction in which the adhesive surface and the adherend are in contact.

[0048] The adhesive structure may involve bonding another adherend to the adhesive surface on the opposite side of the adhesive surface of the thermoplastic adhesive sheet to which the adherend is integrated, or, if the adherend is integrated to a part of the adhesive surface of the thermoplastic adhesive sheet, another adherend may be bonded to the portion of the adhesive surface of the thermoplastic adhesive sheet to which the adherend is integrated that is not integrated.

[0049] <How to use thermoplastic adhesive sheets> A thermoplastic adhesive sheet can bond a workpiece by bringing the workpiece into contact with at least a portion of its bonding surface and heating it to a temperature above the softening point of the thermoplastic resin, thereby softening the thermoplastic resin. Even when one side of the thermoplastic adhesive sheet is the bonding surface and the other side is the non-bonding surface, depending on the form of the thermoplastic resin and insulating reinforced fiber sheet, and the bonding conditions, the thermoplastic resin can flow to the non-bonding surface and bond the workpiece in contact with the non-bonding surface.

[0050] Thermoplastic adhesive sheets can bond adherends to each other. 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 part of the same surface of the thermoplastic adhesive sheet. Since the thermoplastic adhesive sheet can ensure insulation through the insulating reinforcement 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 interposing the thermoplastic adhesive sheet between the adherends and applying pressure from at least one of the adherends in the lamination direction of the thermoplastic adhesive sheet while heating it to a temperature above the softening point of the thermoplastic resin to bond the adherends together.

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

[0053] In Figure 1A, the adherend 12, thermoplastic adhesive sheet 11, and adherend 12' are laminated in that order, and pressure is applied from one side of the adherend 12 in the lamination direction (direction of the arrow in Figure 1A) while heating to above the softening point of the thermoplastic resin in the thermoplastic adhesive sheet 11. By heating above the softening point of the thermoplastic resin, the thermoplastic resin softens, allowing adhesion between the adherend 12 and the thermoplastic adhesive sheet 11, and between the thermoplastic adhesive sheet 11 and adherend 12', which are pressed together under pressure. This allows adherends 12 and 12' to be bonded to each other, and because the thermoplastic adhesive sheet 11 is interposed, contact between adherends 12 and 12' can be suppressed, thus ensuring insulation.

[0054] The adherends 12 and 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 heated and pressurized to bond them together to form an adhesive structure, and then the adhesive structure and the adherend 12' may be heated and pressurized to bond the adherend 12' to the thermoplastic adhesive sheet 11.

[0055] Known methods can be used for heating and pressurizing during bonding, such as hot pressing with a heated press plate, or applying a load in a heated atmosphere such as a heating furnace. Depending on the shape of the adherend 12', pressure may be applied simultaneously from both the adherend 12 side and the adherend 12' side.

[0056] The heating temperature is not particularly limited, unless there are restrictions on the heat resistance of the adherends 12,12'. For example, it may be (softening point + 10)°C or higher, preferably (softening point + 30)°C or higher, and more preferably (softening point + 50)°C or higher, based on the softening point of the thermoplastic resin. 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 is more preferably (softening point + 150)°C or lower, particularly from the viewpoint of suppressing the deterioration of the thermoplastic resin.

[0057] Furthermore, the pressure is not particularly limited as long as adhesion is maintained, and may be, for example, 0.001 MPa or higher, preferably 0.01 MPa or higher, and more preferably 0.1 MPa or higher. The upper limit is not particularly limited, but may be, for example, around 20 MPa, and a pressure that does not cause the thermoplastic resin to ooze out of 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, but since prolonged exposure to high temperatures may cause the thermoplastic resin to deteriorate or flow, it is preferable to perform the process for a relatively short time, for example, within 30 minutes, preferably within 15 minutes, and more preferably within 10 minutes. The lower limit is not particularly limited, but may be, for example, around 1 minute.

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

[0059] In Figure 2A, a thermoplastic adhesive sheet 21 and the adherend 22 are inserted into the hole 23 of the adherend 22', and the thermoplastic adhesive sheet 21 is laminated so as to be in contact with the surface of the adherend 22' that forms the hole 23 and the adherend 22. Pressure is applied from the adherend 22 side in the lamination direction (arrow direction in Figure 2A), and the thermoplastic adhesive sheet 21 is heated to a temperature above the softening point of the thermoplastic resin. By heating to a temperature above the softening point of the thermoplastic resin, the thermoplastic resin softens, allowing adhesion between the adherend 22 and the thermoplastic adhesive sheet 21, and between the thermoplastic adhesive sheet 21 and the adherend 22', which are pressed together under pressure. This allows the adherend 22 to be fixed in the hole 23 of the adherend 22', and because the thermoplastic adhesive sheet 21 is interposed, contact between the adherends 22 and 22' can be suppressed, thus 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 without being bonded, or they may be inserted as an bonded structure. If the hole 23 is narrow, it is preferable that the thermoplastic adhesive sheet 21 and the adherend 22 be an integrated bonded structure.

[0061] One or more thermoplastic adhesive sheets 21 may be used, but if the holes 23 are narrow, it is preferable to interpose one thermoplastic adhesive sheet 21 between the adherends 22 and 22'.

[0062] One method of applying pressure is to apply a load from the adherend 22 side. In particular, if the hole 23 is narrow, an expandable sheet may be inserted between the side of the adherend 22 opposite to the thermoplastic adhesive sheet 21 and the surface of the adherend 22' forming the hole 23, and pressure may be applied by the stress caused by expansion. Examples of expandable sheets include composite sheets composed of reinforcing fibers and resin, which expand due to the resilience force generated by the reinforcing fibers when the resin is softened by heating. Such expandable sheets that expand with heating can be suitably used because they can be expanded and applied pressure simultaneously with the bonding of the thermoplastic adhesive sheet by heating.

[0063] Thermoplastic adhesive sheets can be suitably used as insulating adhesives that can insulate and bond materials together in transportation systems, home appliances, industrial machinery, buildings, and the like. Furthermore, depending on the form of the thermoplastic resin and insulating reinforced fiber sheet, thermoplastic adhesive sheets can have heat resistance and can therefore be suitably used as heat-resistant adhesives.

[0064] For example, in a motor (e.g., a motor for driving automobiles), by using this material as a fixing agent to adhesively fix permanent magnets in a plurality of holes or recesses formed in the rotor or stator, it is possible to fix the permanent magnets with sufficient adhesive strength while also providing insulation.

[0065] For example, motors that use permanent magnets in the rotor include embedded permanent magnet motors (IPM motors) and surface permanent magnet motors (SPM motors). In SPM motors, permanent magnets are fixed in each recess on the rotor surface, while in IPM motors, permanent magnets are fixed in each hole in the rotor. Thermoplastic adhesive sheets are preferable to IPM motors, which are useful for high-speed rotation, because of their excellent adhesive properties. [Examples]

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

[0067] [Glass transition temperature (Tg) of thermoplastic resins] The glass transition temperature of thermoplastic resins was determined using a Rheospectra DVE-V4 solid dynamic viscoelasticity analyzer manufactured by Rheology Inc., by measuring the temperature dependence of the loss tangent (tanδ) at a frequency of 10 Hz and a heating rate of 10 °C / min, and then determining the peak temperature. Here, the peak temperature of tanδ is the temperature at which the first derivative of the change in the value of tanδ with respect to temperature becomes zero.

[0068] [Basis weight of thermoplastic resin sheets and insulating reinforced fiber sheets] Samples of thermoplastic resin sheets and insulating reinforced fiber sheets measuring 250mm x 250mm were cut into 80 small pieces measuring 50mm x 15mm, and the weight (g) of each piece was measured to determine the basis weight (g / m²). 2 ) is calculated, and the average weight of all small pieces is used as the weight (g / m²) of each sample. 2 )

[0069] [Thickness of the insulating reinforced fiber sheet] A sample of an insulating reinforced 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. The thickness (μm) of the center of each piece was measured using a high-precision digital micrometer "MDH-25MB" manufactured by Mitutoyo Corporation, and the average thickness of all the pieces was taken as the thickness (μm) of the insulating reinforced fiber sheet.

[0070] [Density of thermoplastic resins and insulating reinforced fibers] The density of thermoplastic resins and insulating reinforcing fibers was determined by measuring the density of each sample at 25°C using the water displacement method with the "ELECTRONIC DENSIMETER SD-200L" hydrometer manufactured by Alpha Mirage Co., Ltd. The measurement was repeated five times with 10g of each sample, and the average value was used to determine the density (g / cm³) of each sample. 3 )

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

[0072] [Theoretical thickness of thermoplastic adhesive sheets] Based on the basis weight (weight per unit area), volume ratio, and density of the insulating reinforced fiber sheets measured above, the theoretical thickness (μm) of the thermoplastic adhesive sheet was calculated using the following formula. T = Mp / σp + Mf / σf (In the formula, T: theoretical thickness [μm], Mp: weight per unit area of ​​thermoplastic resin [g / m²]) 2 ], σp: Density of thermoplastic resin [g / cm³] 3 ], Mf: Weight per unit area of ​​insulating reinforced fiber sheet [g / m 2 ], σf: Density of insulating reinforcing fibers [g / cm³] 3 ])

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

[0074] [Shear bond strength] The shear bond strength of a thermoplastic adhesive sheet to an iron test piece was measured, referring to JIS K 6850 "Adhesives - Test method for tensile shear bond strength of rigid adherends". Two iron test pieces (Standard Test Piece Co., Ltd., SPCC-SD; 1.6 mm thick, 100 mm long, 25 mm wide) were prepared. A thermoplastic adhesive sheet cut to 10 mm vertically and 25 mm horizontally was placed on a 10 mm long and 25 mm wide area at the end of one iron test piece. Using a test press machine (Kitagawa Seiki Co., Ltd., "KVHC-II"), the iron test piece was bonded to one side of the thermoplastic adhesive sheet by pressing at a specified temperature, 2 MPa, and for 1 minute. Then, the 10 mm long and 25 mm wide area at the end of the other iron test piece was placed on the other side of the thermoplastic adhesive sheet, and the sample for shear bond strength measurement was prepared by holding it in a hot air furnace at a specified temperature for 10 minutes under a load of 0.04 MPa. For the obtained samples for measuring shear bond strength, a tensile testing machine (Shimadzu Corporation "AG-5000B") was used. Each iron test piece was gripped and pulled at a tensile speed of 1 mm / min, and the shear bond strength (MPa) was measured from the load at which it broke. The measurement was performed five times, and the average value was calculated.

[0075] [Insulating properties] In the above-mentioned shear bond strength measurement sample, before measuring the shear bond strength, the needle of a tester (HiTESTER 3244-60, manufactured by HIOKI E.E. CORPORATION) was touched to the center of the width direction and 10 mm from the end direction of the length direction of the upper and lower iron test pieces, respectively, and the resistance value was measured. If the resistance value was above the detection limit (42 MΩ), the insulation performance was evaluated as A; if no resistance was detected, the insulation performance was evaluated as B.

[0076] [warp] The obtained thermoplastic adhesive sheets were visually inspected and evaluated as follows: A if there was no warping, B if there was slight warping, and C if there was significant warping.

[0077] [Damaged load] Using a load-variable friction abrasion test system ("Tribogear HHS2000" manufactured by Shinto Kagaku Co., Ltd.), the surface of a thermoplastic adhesive sheet was scratched with a sapphire scratching needle with a radius of R0.1 mm at a speed of 1 mm / s, while continuously increasing the load from 0 to 500 g. 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 defined as the load at which damage to the insulating reinforcing fibers of the thermoplastic adhesive sheet was observed. Three measurements were performed, and the average value was calculated.

[0078] [Example 1] An amorphous thermoplastic resin, polyetherimide (hereinafter sometimes abbreviated as PEI), a polymer (ULTEM9001, manufactured by Cervical Innovative Plastics, Inc.) was vacuum-dried at 150°C for 12 hours. The above PEI polymer was extruded using an extruder and supplied to a meltblown nonwoven fabric manufacturing apparatus having a nozzle with a nozzle diameter D (diameter) of 0.4 mm, a nozzle length / D ratio of 7.5, and a nozzle hole pitch of 0.68 mm. The single-hole discharge rate 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 Air was blown onto the material at a rate of [number] minutes to obtain a meltblown nonwoven fabric. The resulting meltblown nonwoven fabric had a basis weight of 35 g / m². 2 The glass transition temperature (softening point in amorphous thermoplastic resins) is 217°C, and the density is 1.27 g / cm³. 3 That was the case.

[0079] PEI meltblown nonwoven fabric obtained as a thermoplastic resin sheet, and glass cloth (basis weight 12g / m²) obtained as an insulating reinforced fiber sheet. 2 Thickness 0.015 mm, glass fiber density 2.54 g / cm³ 3Using a PEI meltblown nonwoven fabric, the layers were laminated in the order of PEI meltblown nonwoven fabric / glass cloth / PEI meltblown nonwoven fabric. Using a test press machine (KVHC-II manufactured by Kitagawa Seiki Co., Ltd.), the layers were hot-pressed at 300°C in the lamination direction at 2 MPa for 1 minute, impregnating the glass fibers with molten PEI polymer to produce a thermoplastic adhesive sheet. The resulting thermoplastic adhesive sheet showed no warping.

[0080] The obtained thermoplastic adhesive sheets were subjected to various evaluations, and the evaluation results are shown in Table 1. The test press machine temperature was set to 300°C and the hot air furnace temperature to 320°C when preparing the samples for shear bond strength measurement.

[0081] [Example 2] Glass cloth as an insulating reinforced fiber sheet (Unitika Ltd. "H25X104HE"; basis weight 24.5g / m²) 2 Thickness 0.03 mm, glass fiber density 2.54 g / cm³ 3 A thermoplastic adhesive sheet was prepared in the same manner as in Example 1, except that a different material was used, and various evaluations were performed. The obtained thermoplastic adhesive sheet showed no warping.

[0082] [Example 3] A thermoplastic adhesive sheet was prepared in the same manner as in Example 1, except that three layers of glass cloth used in Example 2 were used as the insulating reinforced fiber sheet, and various evaluations were performed. The obtained thermoplastic adhesive sheet showed no warping.

[0083] [Example 4] In the production of meltblown nonwoven fabric, the basis weight of the resulting PEI meltblown nonwoven fabric is 25 g / m². 2 A PEI meltblown nonwoven fabric was obtained in the same manner as in Example 1, except that it was adjusted to achieve the desired result. A thermoplastic adhesive sheet was prepared 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 reinforced fiber sheet, and various evaluations were performed. The obtained thermoplastic adhesive sheet showed no warping.

[0084] [Example 5] A crystalline thermoplastic resin, polyether ether ketone (hereinafter sometimes abbreviated as PEEK), was vacuum-dried at 80°C for 12 hours using a polymer (Victrex "90G"). 0.35 g of the PEEK polymer was placed inside a metal frame with internal dimensions of 100 mm × 100 mm × thickness of 25 μm, which was set on a polyimide film. The film was then pressed using a test press machine (Kitagawa Seiki Co., Ltd. "KVHC-II") at 380°C, 2 MPa, and 1 minute to obtain a film. The resulting film had a basis weight of 33 g / m². 2 Its melting point (softening point in crystalline thermoplastic resins) is 343°C, and its density is 1.30 g / cm³. 3 The results were as follows. A thermoplastic adhesive sheet was prepared in the same manner as in Example 1, except that the PEEK film obtained as the thermoplastic resin sheet and the glass cloth used in Example 2 as the insulating reinforced fiber sheet were used, and various evaluations were performed. The obtained thermoplastic adhesive sheet did not warp. The test press machine temperature was set to 380°C and the hot air furnace temperature was set to 380°C when preparing the sample for shear adhesive strength measurement.

[0085] [Example 6] An amorphous thermoplastic phenoxy polymer (Yp50s, manufactured by Nippon Steel Chemical & Material Co., Ltd.) was vacuum-dried at 60°C for 12 hours. The phenoxy polymer was extruded using an extruder and supplied to a meltblown nonwoven fabric manufacturing apparatus having a nozzle with a nozzle diameter D of 0.3 mm, nozzle length / D = 7.5, and nozzle hole pitch of 0.68 mm. The single-hole discharge rate 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 was obtained by blowing air at a rate of [number] minutes. The resulting meltblown nonwoven fabric had a basis weight of 30 g / m². 2 The glass transition temperature (softening point in amorphous thermoplastic resins) is 84°C, and the density is 1.17 g / cm³. 3 That was the case.

[0086] A phenoxymeltblown nonwoven fabric was obtained as the thermoplastic resin sheet, and the glass cloth used in Example 2 was used as the insulating reinforcement fiber sheet. The layers were laminated in the order of phenoxymeltblown nonwoven fabric / glass cloth / phenoxymeltblown nonwoven fabric. Using a test press machine (KVHC-II, manufactured by Kitagawa Seiki Co., Ltd.), the layers were hot-pressed at 2 MPa for 1 minute at 200°C in the lamination direction to impregnate the glass fibers with molten phenoxy polymer, thereby producing a thermoplastic adhesive sheet. The resulting thermoplastic adhesive sheet showed no warping. The test press machine temperature was set to 200°C and the hot air furnace temperature to 220°C when preparing the sample for shear adhesive strength measurement.

[0087] [Example 7] A thermoplastic adhesive sheet was prepared 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 reinforcement fiber sheet, and the layers were laminated in the order of two PEI meltblown nonwoven fabrics per glass cloth. Various evaluations were then performed on the resulting thermoplastic adhesive sheet.

[0088] [Example 8] A thermoplastic adhesive sheet was prepared 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 reinforcement fiber sheet, and the layers were laminated in the order of 2 sheets of PEI meltblown nonwoven fabric and 3 sheets of glass cloth. Various evaluations were then performed on the resulting thermoplastic adhesive sheet. The obtained thermoplastic adhesive sheet was slightly warped.

[0089] [Example 9] A thermoplastic adhesive sheet was prepared in the same manner as in Example 1, except that two layers of glass cloth, as used in Example 2, were used as the insulating reinforced fiber sheet, and various evaluations were performed. The obtained thermoplastic adhesive sheet showed no warping.

[0090] [Example 10] A thermoplastic adhesive sheet was prepared 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 reinforced fiber sheet, and the layers were laminated in the order of one sheet of glass cloth / two sheets of PEI meltblown nonwoven fabric / one sheet of glass cloth. Various evaluations were then performed on the prepared thermoplastic adhesive sheet. The obtained thermoplastic adhesive sheet showed no warping.

[0091] [Comparative Example 1] A thermoplastic adhesive sheet was prepared 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 glass cloth used in Example 2 were used as the insulating reinforced fiber sheet. Various evaluations were then performed. The obtained thermoplastic adhesive sheet showed no warping.

[0092] [Comparative Example 2] A thermoplastic adhesive sheet was prepared in the same manner as in Example 1, except that glass cloth was not used, and various evaluations were performed. The obtained thermoplastic adhesive sheet showed no warping.

[0093] [Comparative Example 3] A thermoplastic adhesive sheet was prepared 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 reinforced fiber sheet, and the layers were laminated in the order of 2 sheets of PEI meltblown nonwoven fabric and 5 sheets of glass cloth. Various evaluations were then performed on the prepared thermoplastic adhesive sheet. The obtained thermoplastic adhesive sheet showed no warping.

[0094] [Table 1]

[0095] As shown in Table 1, the thermoplastic adhesive sheets of Examples 1 to 10 exhibited high shear adhesive strength when bonding iron test pieces as adherends, ensuring insulation. In particular, the thermoplastic adhesive sheets of Examples 1 to 6 and 9 showed no warping because the exposure rate of the insulating reinforcing fiber sheet on both sides was reduced. Furthermore, the thermoplastic adhesive sheets of Examples 2, 4 and 9 had high scratch load resistance and excellent insertability into narrow spaces.

[0096] On the other hand, the thermoplastic adhesive sheets of Comparative Examples 1 and 3 have a volume ratio of insulating reinforced fiber sheets that is too large, resulting in lower shear adhesive strength compared to Examples 1 to 10, and thus failing to exhibit sufficient adhesion.

[0097] The thermoplastic adhesive sheet in Comparative Example 2 does not contain an insulating reinforced fiber sheet, and therefore fails to suppress contact between iron test pieces, thus failing to ensure insulation. [Industrial applicability]

[0098] Thermoplastic adhesive sheets are useful for insulating and bonding materials together in transportation equipment, home appliances, industrial machinery, buildings, and other applications. For example, thermoplastic adhesive sheets can be used in motors as fixing materials for bonding and securing permanent magnets within multiple holes formed in the rotor or stator.

[0099] As described above with reference to the drawings, preferred embodiments of the present invention have been explained. However, those skilled in the art will readily anticipate various changes and modifications within the obvious scope by reviewing this specification. Therefore, such changes and modifications will be interpreted as falling within the scope of the invention as defined by the claims. [Explanation of Symbols]

[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 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%, both sides of the thermoplastic adhesive sheet are adhesive surfaces, and the exposure rate of the insulating reinforcing fiber sheet on each adhesive surface is less than 10%.

2. 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%, the weight Mf per unit area of ​​the insulating reinforcing fiber sheet is 10 to 79 g / m², and the theoretical thickness T represented by the following formula (1) is 20 to 150 μm. T=Mp / σp+Mf / σf (1) (In the formula, T: theoretical thickness [μm], Mp: weight per unit area of ​​thermoplastic resin [g / m²], σp: density of thermoplastic resin [g / cm³], Mf: weight per unit area of ​​insulating reinforced fiber sheet [g / m²], σf: density of insulating reinforced fiber [g / cm³])

3. A thermoplastic adhesive sheet comprising a thermoplastic resin and an insulating reinforced fiber sheet, having an adhesive surface bonded by the thermoplastic resin, wherein the volume ratio of the insulating reinforced fiber sheet to the total volume of the thermoplastic resin and the insulating reinforced fiber sheet is 2 to 50 vol%, and the insulating reinforced fiber sheet is an insulating reinforced fiber fabric.

4. 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%, the insulating reinforcing fiber sheet is composed of long fibers, and the maximum expansion rate in the thickness direction of the thermoplastic adhesive sheet is 50% or less.

5. A thermoplastic adhesive sheet according to any one of claims 1 to 4, wherein the insulating reinforcing fiber sheet is a glass fiber fabric.

6. A thermoplastic adhesive sheet according to any one of claims 1 to 4, wherein the thickness of the insulating reinforcing fiber sheet is 10 to 150 μm.

7. A thermoplastic adhesive sheet according to any one of claims 1 to 4, wherein the glass transition temperature of the thermoplastic resin is 100°C or higher.

8. A thermoplastic adhesive sheet according to any one of claims 1 to 4, wherein the thermoplastic resin is an amorphous thermoplastic resin.

9. A thermoplastic adhesive sheet according to any one of claims 1 to 4, 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.

10. An adhesive structure comprising a thermoplastic adhesive sheet according to any one of claims 1 to 4, and a workpiece integrated in contact with at least a portion of the adhesive surface thereof.

11. A method of using the thermoplastic adhesive sheet according to any one of claims 1 to 4, wherein the thermoplastic adhesive sheet is interposed between adherends, and the adherends are bonded together by heating the sheet at a temperature above 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.

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

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