Cushioning material for hot press molding, and method for manufacturing a cushioning material for hot press molding

Abstract

To provide a felt material that provides a cushioning material for hot press molding that has higher heat resistance and durability than conventional cushion materials for hot press molding, and to provide a novel felt material containing specific fibers that have not been used in a base material layer in the same layer.SOLUTION: There is provided a felt material 1 including base material layers and a batt fiber layer 20, in which at least one of the base material layers is a heat-resistant base layer 10 containing at least one type of fiber selected from the group consisting of polyphenylene oxadiazole fibers and polyoxadiazole fibers.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] This invention relates to felt material, cushioning material for hot press molding, and a method for manufacturing felt material. [Background technology]

[0002] In the manufacturing of electrical components with a laminated structure, such as printed circuit boards, hot pressing is performed for the purpose of press molding or thermocompression bonding of the laminate. Printed circuit boards are manufactured, for example, by laminating a resin prepreg and copper foil, and then applying pressure and heating with a hot plate, i.e., by hot pressing. In hot pressing, the prepreg generally decreases in viscosity upon heating and returns to a liquid state, after which it gradually hardens. In such hot pressing, it is required that the distribution of pressure and temperature applied to the laminate be uniform.

[0003] For this reason, heat-resistant felt is commonly used as a cushioning material for hot press molding. The cushioning material for hot press molding is placed between the hot platen and the laminated body, and by distributing the pressure and temperature applied from the hot platen in the planar direction, it is possible to equalize the pressure and temperature distribution in hot press molding. Therefore, the cushioning material for hot press molding and the felt material used therein are required to have basic properties such as appropriate deformation followability, cushioning properties, thermal conductivity, dimensional stability, durability, and heat resistance in order to equalize the pressure and temperature distribution.

[0004] Patent Document 1 describes a heat-resistant felt material for use during heat pressing of printed circuit boards, etc., which includes a base layer having at least one base material, and discloses that the base material includes a base fabric having yarn containing at least one fiber selected from the group consisting of aromatic polyamide fibers and poly(p-phenylenebenzobisoxazole) fibers (hereinafter also referred to as "PBO fibers").

[0005] Furthermore, Patent Document 2 describes a heat-resistant cushioning material including an inorganic fiber layer and a heat-resistant organic fiber layer, and discloses that basalt fibers and PBO fibers were used as the inorganic fibers and heat-resistant organic fibers, respectively. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2021-160092 [Patent Document 2] Japanese Patent Publication No. 2017-095840 [Overview of the project] [Problems that the invention aims to solve]

[0007] In the process of manufacturing printed circuit boards, the cushioning materials and felt materials used for heat press molding, which are used when press-molding or heat-compressing target products, require higher heat resistance than before due to the higher press molding temperatures, and also require greater durability from a cost-saving perspective.

[0008] In the hot press molding cushion material described in Patent Document 1, heat resistance is improved by using heat-resistant fibers such as aromatic polyamide fibers and PBO fibers in the base material (woven fabric, base cloth) and the web (nonwoven fabric) laminated to the base material, which are its constituent elements.

[0009] Furthermore, in the heat-resistant cushioning material described in Patent Document 2, both sides of the inorganic fiber layer are sandwiched between heat-resistant organic fiber layers. The low thermal conductivity of the inorganic fiber layer suppresses heat conduction to the heat-resistant organic fiber layer below it, thereby preventing deterioration of the heat-resistant organic fiber layer and improving the durability of the heat-resistant cushioning material.

[0010] The conventional cushion material for hot press molding using the above-mentioned conventional felt material exhibits sufficient heat resistance and durability against hot pressing under conditions of 180 to 200°C. However, in recent years, substrates that require hot pressing under higher temperature conditions have also emerged, and hot pressing under conditions of temperatures exceeding 250°C or 300°C and press pressures reaching 120kg / cm 2 is sometimes required. When conventional cushion materials for hot press molding are subjected to multiple rounds of hot pressing under such high-temperature and high-pressure conditions, the fiber strength may decrease significantly due to thermal degradation, and their heat resistance and durability have gradually become not necessarily sufficient. Furthermore, from the viewpoints of environmental protection and the health and safety of workers, the use of inorganic materials such as glass fibers to improve heat resistance and durability should be avoided as much as possible.

[0011] The present invention has been made in view of the above-mentioned conventional circumstances, and an object of the present invention is to provide a felt material that provides a cushion material for hot press molding having higher heat resistance and durability than conventional cushion materials for hot press molding. Another object of the present invention is to provide a novel felt material that contains specific fibers, which have never been used in a base material layer, in said layer. [Means for Solving the Problem]

[0012] The inventors of the present invention have conducted intensive studies to solve the above problems, and as a result, have found that the above problems can be solved by employing a heat-resistant base material layer containing specific fibers, and have completed the present invention.

[0013] That is, the present invention relates to the following. [1] Comprising a base material layer and a batt fiber layer, At least one layer among the base material layers is a heat-resistant base material layer containing at least one fiber selected from the group consisting of polyphenylene oxadiazole fibers and polyoxadiazole fibers. The felt material. [2] The felt material according to [1], wherein the batt fiber layer comprises at least one fiber selected from the group consisting of polyphenylene oxadiazole fibers, polyoxadiazole fibers, polyparaphenylene benzobisoxazole fibers, polyimide fibers, aramid fibers and polyphenylene sulfide fibers. [3] The felt material according to [1] or [2], which has a thickness of 1 to 10 mm. [4] At least one of the base material layers has a basis weight of 50 to 500 g / m 2 The felt material according to any one of [1] to [3], which is [5] The felt material according to any one of [1] to [4], further comprising an additional base material layer as the base material layer. [6] The felt material according to [5], wherein the additional base material layer comprises at least one fiber selected from the group consisting of aramid fibers, polyparaphenylene benzobisoxazole fibers, polyimide fibers, fluorine fibers, glass fibers and polyphenylene sulfide fibers.

[0014] [7] A cushion material for hot press molding, comprising the felt material according to any one of [1] to [6]. [8] The method for producing a felt material according to any one of [1] to [6], comprising the following steps (a) and (b) in this order. (a) a step of arranging a fiber web made of batt fibers on at least one surface of the base material layer. (b) a step of forming the batt fiber layer by entanglement of the fiber web and the base material layer with each other. Effects of the Invention

[0015] The felt material of the present invention has high heat resistance and durability. Brief Description of the Drawings

[0016] [Figure 1]Figure 1 is a schematic diagram showing a felt material according to one embodiment of the present invention. [Figure 2] Figure 2 is a schematic diagram showing a felt material according to one embodiment of the present invention. [Figure 3] Figure 3 is a schematic diagram showing a felt material according to one embodiment of the present invention. [Figure 4] Figure 4 is a schematic diagram showing a felt material according to one embodiment of the present invention. [Figure 5] Figure 5 is a schematic diagram showing a felt material according to one embodiment of the present invention. [Figure 6] Figure 6 is a schematic diagram showing a felt material according to one embodiment of the present invention. [Figure 7] Figure 7 is a schematic diagram showing a felt material according to one embodiment of the present invention. [Figure 8] Figure 8 is a schematic diagram showing a felt material according to one embodiment of the present invention. [Figure 9] Figure 9 is a schematic diagram showing an example of the usage state of a cushioning material for hot press molding according to one embodiment of the present invention. [Figure 10] Figure 10 is a schematic diagram showing an example of the usage state of a cushioning material for hot press molding according to one embodiment of the present invention. [Modes for carrying out the invention]

[0017] <Felt material> The felt material according to an embodiment of the present invention comprises a base layer and a butt fiber layer, wherein at least one of the base layers is a heat-resistant base layer containing at least one fiber selected from the group consisting of polyphenylene oxadiazole fibers and polyoxadiazole fibers (hereinafter also referred to as "POD fiber"). Herein, the term "heat-resistant base material layer" in this specification refers to a base material layer containing POD fibers.

[0018] Preferred embodiments of the felt material according to the present invention will be described below with reference to the drawings. In this specification, when the expression "~" is used, it is used to include the numerical value or physical property value before and after it.

[0019] The felt material according to the embodiment of the present invention can be, for example, a laminate having a flat plate shape, as shown in Figures 1 and 2. Furthermore, as shown in Figures 1 and 2, the felt material 1 according to the embodiment of the present invention includes a heat-resistant base material layer 10 and a butt fiber layer 20.

[0020] There are no particular restrictions on the thickness of the felt material according to the embodiments of the present invention, but from the viewpoint of cushioning, it is preferably 1 mm to 10 mm, more preferably 2 mm to 8 mm, and even more preferably 3 mm to 7 mm.

[0021] Furthermore, there are no particular restrictions on the basis weight of the felt material according to the embodiments of the present invention, but from the viewpoint of cushioning and thermal conductivity, 150 g / m² is recommended. 2 ~5000g / m 2 Preferably, it is 300g / m 2 ~4000g / m 2 It is more preferable that it be 400g / m 2 ~3000g / m 2 It is even more preferable that this is the case. In addition, multiple layers of these felt materials can be used to adjust the cushioning and heat conductivity.

[0022] [Base material layer] The felt material according to an embodiment of the present invention comprises one or more base layers, wherein at least one of the base layers is a heat-resistant base layer containing at least one fiber selected from the group consisting of polyphenylene oxadiazole fibers and polyoxadiazole fibers. In other words, at least one of the base layers included in the felt material according to an embodiment of the present invention is a heat-resistant base layer containing POD fibers. As a result, the felt material according to the embodiment of the present invention can have high heat resistance and durability.

[0023] The polyphenylene oxadiazole and polyoxadiazole constituting the POD fiber are also called polyphenylene-1,3,4-oxadiazole and poly-1,3,4-oxadiazole, respectively. Furthermore, polyphenylene oxadiazole has ortho (o-), meta (m-), and para (p-) isomers with respect to the phenylene moiety. In embodiments of the present invention, from the viewpoint of heat resistance, it is preferable to use poly(m-phenylene oxadiazole) as the meta isomer, poly(p-phenylene oxadiazole) as the para isomer, or poly(m-phenylene)(p-phenylene)oxadiazole, which is a copolymer of the meta and para isomers, or a combination thereof, and it is more preferable to use poly(m-phenylene)(p-phenylene)oxadiazole. The same applies to the structure of the POD fiber and its preferred embodiments referred to herein.

[0024] There are no particular restrictions on the proportion of POD fibers in the heat-resistant base material layer, but from the viewpoint of obtaining high heat resistance and durability, the fiber composition ratio is preferably 50% to 100% by mass, more preferably 75% to 100% by mass, even more preferably 90% to 100% by mass, and particularly preferably 100% by mass.

[0025] Examples of fibers other than POD fibers that can be included in the heat-resistant substrate layer include aramid fibers, PBO fibers, polyimide fibers, fluorine fibers, glass fibers, and polyphenylene sulfide fibers. Aramid fibers have ortho (o-), meta (m-), and para (p-) isomers with respect to the phenylene moiety. In embodiments of the present invention, from the viewpoint of shape stability, it is more preferable to use m-aramid fibers (meta-isomer), p-aramid fibers (para-isomer), mp-aramid fibers (a copolymer of meta- and para-isomers), or combinations thereof as aramid fibers. The same applies to the structures and preferred embodiments of aramid fibers mentioned herein.

[0026] Furthermore, the felt material according to the embodiment of the present invention may further include an additional base layer as a base layer. Herein, "additional base layer" as used herein refers to a base layer that does not contain POD fibers. Examples of additional base material layers include base material layers containing at least one fiber selected from the group consisting of aramid fibers, poly(p-phenylenebenzobisoxazole) fibers, polyimide fibers, fluorine fibers, glass fibers, and polyphenylene sulfide fibers. However, from the viewpoint of heat resistance, it is preferable that the felt material according to the embodiment of the present invention contains only a heat-resistant base material layer. Specific embodiments of the felt material according to embodiments of the present invention that include an additional base material layer include, for example, the embodiments shown in Figures 3 to 5. As shown in Figures 3 to 5, in addition to the heat-resistant base material layer 10, an additional base material layer 10A that does not contain POD fibers may be further included.

[0027] The felt material according to embodiments of the present invention may contain only one base layer (i.e., only one heat-resistant base layer), or it may contain two or more base layers. From the viewpoint of durability and dimensional stability, it is preferable to contain two or more base layers, more preferably two, three or four layers, and even more preferably three layers. When the felt material according to an embodiment of the present invention includes two or more base layers, the base layers may include both a heat-resistant base layer 10 and an additional base layer 10A, as shown in Figures 3 to 5, or they may include two or more layers of only the heat-resistant base layer 10, as shown in Figures 6 to 8.

[0028] The base layer can be made of, for example, a woven fabric or a grid-like material. The woven fabric and grid-like material may be formed using spun yarn or filament yarn obtained from fibers. If the base layer is a woven fabric, the structure of the woven fabric is not particularly limited, and any of plain weave, twill weave, satin weave, or multi-layer weave using these can be used. When the felt material according to an embodiment of the present invention includes two or more base material layers, each layer may be constituted by the aforementioned woven fabric or grid-shaped material.

[0029] There is no particular restriction on the thickness of the base material layer, but from the viewpoint of smoothness, the thickness is preferably 0.1 mm to 2 mm, more preferably 0.2 mm to 1.5 mm, and still more preferably 0.3 mm to 1 mm. When the felt material according to an embodiment of the present invention includes two or more base material layers, it is preferable that at least one base material layer satisfies the aforementioned thickness, and it is more preferable that all base material layers satisfy the aforementioned thickness.

[0030] There is no particular restriction on the basis weight of the base material layer, but from the viewpoints of cushioning properties and thermal conductivity, 50 g / m 2 to 500 g / m 2 is preferable, 60 g / m 2 to 400 g / m 2 is more preferable, and 80 g / m 2 to 300 g / m 2 is even more preferable. When the felt material according to an embodiment of the present invention includes two or more base material layers, it is preferable that at least one base material layer satisfies the aforementioned basis weight, and it is more preferable that all base material layers satisfy the aforementioned basis weight.

[0031] [Bat fiber layer] The bat fiber layer included in the felt material according to an embodiment of the present invention is a layer constituted by bat fibers. More specifically, the bat fiber layer is a fiber aggregate layer formed by intertwining bat fibers (preferably bat fibers that are short fibers) with each other, and in one embodiment, functions as a layer having thermal conductivity, cushioning properties and the like.

[0032] There are no particular restrictions on the butt fibers that make up the butt fiber layer, but from the viewpoint of heat resistance, it is preferable that it contains at least one fiber selected from the group consisting of polyphenylene oxadiazole fiber, polyoxadiazole fiber, polyparaphenylene benzobisoxazole fiber, polyimide fiber (hereinafter also referred to as "PI fiber"), aramid fiber, and polyphenylene sulfide fiber, and it is more preferable that it is POD fiber, PBO fiber, or PI fiber, and even more preferable that it is POD fiber.

[0033] The felt material 1 according to an embodiment of the present invention may include only one butt fiber layer 20, as shown in Figures 2 and 6. Alternatively, the felt material 1 according to an embodiment of the present invention may include two or more butt fiber layers 20, 20A, as shown in Figures 1, 3 to 5, 7 and 8. Furthermore, in the embodiment of the present invention, it is preferable that the felt material 1 includes butt fiber layers 20 and 20A as the outermost layers in the lamination direction. When the felt material 1 includes two or more butt fiber layers 20 and 20A, it is preferable that both of the two outermost layers in the lamination direction are butt fiber layers 20 and 20A, as shown in Figures 1, 3, 4, 7 and 8.

[0034] When the felt material according to the embodiment of the present invention is used as a cushioning material for hot press molding described later, it is preferable, and more preferable, to include two or more butt fiber layers from the viewpoint of ease of use. In this case, in a preferred embodiment, the butt fiber layers are arranged to be in contact with the heating plate of the double-sided printed circuit board manufacturing apparatus described later.

[0035] The butt fiber layer is preferably laminated adjacent to at least one surface of the base layer, and may also be laminated adjacent to both surfaces of the base layer. For example, a butt fiber layer laminated adjacent to the base layer can be formed by arranging a fiber web made of butt fibers on the base layer, entangling them with each other by needle punching, and entangling them with the base layer.

[0036] There are no particular restrictions on the fiber length of the butt fibers that make up the butt fiber layer, but from the viewpoint of smoothness, it is preferably 30 mm to 90 mm, more preferably 35 mm to 85 mm, and even more preferably 40 mm to 80 mm. When the felt material according to an embodiment of the present invention includes two or more butt fiber layers, it is preferable that at least one butt fiber layer satisfies the fiber length, and more preferably that all butt fiber layers satisfy the fiber length.

[0037] There are no particular restrictions on the fineness of the butt fibers that make up the butt fiber layer, but from the viewpoint of cushioning, it is preferably 0.5 dtex to 10 dtex, more preferably 1 dtex to 8 dtex, and even more preferably 1.5 dtex to 7 dtex. When the felt material according to an embodiment of the present invention includes two or more butt fiber layers, it is preferable that at least one butt fiber layer satisfies the fineness requirement, and it is more preferable that all butt fiber layers satisfy the fineness requirement.

[0038] There are no particular restrictions on the basis weight of the bat fiber layer, but from the viewpoint of cushioning and thermal conductivity, 200 g / m² is recommended. 2 ~4700g / m 2 Preferably, it is 300g / m 2 ~3700g / m 2 It is more preferable that it be 400g / m 2 ~2700g / m 2 It is even more preferable that this be the case. When the felt material according to an embodiment of the present invention includes two or more butt fiber layers, it is preferable that at least one butt fiber layer satisfies the basis weight, and it is more preferable that all butt fiber layers satisfy the basis weight.

[0039] There are no particular restrictions on the thickness of the butt fiber layer, but from the viewpoint of cushioning and thermal conductivity, it is preferably 0.7 mm to 8 mm, more preferably 1.2 mm to 7 mm, and even more preferably 1.7 mm to 6 mm. When the felt material according to an embodiment of the present invention includes two or more butt fiber layers, it is preferable that at least one butt fiber layer satisfies the aforementioned thickness, and it is more preferable that all butt fiber layers satisfies the aforementioned thickness.

[0040] From the viewpoint of smoothness and ease of use, the felt material according to the embodiment of the present invention preferably includes one or two layers of butt fiber layers as the outermost layer in the lamination direction, and more preferably includes one layer each of two layers of butt fiber layers as the outermost layer in the lamination direction.

[0041] [Other layers] The felt material according to the embodiment of the present invention may include other layers in addition to the base layer and the butt fiber layer. Examples of other layers include a film layer, a paper layer, and the like. The felt material according to the embodiment of the present invention preferably comprises only a base layer and a butt fiber layer.

[0042] [shape] The felt material according to the embodiment of the present invention can be in various shapes depending on its application, and for example, it can be a laminate in the shape of a flat plate, a belt, or a cylinder.

[0043] [Application] The felt material according to the embodiment of the present invention has high heat resistance and durability, making it suitable for use under high temperature and high pressure conditions. Examples of such applications include cushioning material for hot press molding, as well as sealing material, spacers, and gaskets for high-temperature furnaces.

[0044] <Cushioning material for heat press molding> The cushioning material for hot press molding according to an embodiment of the present invention includes the felt material described above. The following describes specific examples of the use of the heat-press molding cushion material according to embodiments of the present invention, based on a pressing process (heat pressing) using the double-sided printed circuit board manufacturing apparatus shown in Figures 9 and 10.

[0045] Figure 9 shows one embodiment of a process in which a laminate made of resin prepreg and copper foil is heat-pressed using a heat-press molding cushion material. In this embodiment, the object to be heat-pressed is described as a laminate 300 serving as a precursor for a printed circuit board.

[0046] As shown in Figure 9, the hot press is performed by compressing the laminated board 300 with a pair of heated heating plates 100. Also, as shown in Figure 9, the hot press can be performed on multiple laminated boards 300 simultaneously. In this example, the cushioning material 400 for hot press molding is in the shape of a flat plate.

[0047] Figure 10 is an enlarged view of one set of laminated boards 300 sandwiched between mirrored plates 200 shown in Figure 9. As shown in Figure 10, the laminated board 300 has metal foils 302 such as copper foil arranged on both sides of the prepreg 301. The prepreg 301 is made by stacking multiple sheets of glass cloth impregnated with a curable resin and in a semi-cured state.

[0048] As shown in Figure 9, mirror-finish plates 200, such as stainless steel plates, are placed between the multiple laminated plates 300 to prevent direct contact between them and for surface shaping. In addition, mirror-finish plates 200 are also placed above the laminated plate 300 at the upper end and below the laminated plate 300 at the lower end to avoid direct contact with the heat press molding cushioning material 400 and the heating plate 100, and for surface shaping.

[0049] The object to be pressed, which consists of a laminated board 300 and a mirrored plate 200, is then pressed by a hot plate 100 via a hot press forming cushion material 400 positioned above and below it. The hot press forming cushion material 400 has appropriate thermal conductivity, deformation-following ability, and cushioning properties, and has the function of uniformly transmitting the pressure and heat from the hot plate 100 to the object to be pressed, which consists of a laminated board 300 and a mirrored plate 200.

[0050] As shown in Figure 10, if we consider the metal foil 302 and prepreg 301 sandwiched between mirror plates 200 as one set, approximately 10 to 20 sets are pressed in one pressing process. In addition, the cushioning material 400 for hot press molding is generally required to withstand approximately 200 to 1000 pressing processes.

[0051] The pressing conditions in the aforementioned pressing process are typically a hot plate temperature of 150°C to 250°C and a pressure of 20 kg / cm² between the hot plates. 2 ~100kg / cm 2 That's about it. However, in recent years, the demand for heat resistance in printed circuit boards has increased, so the temperature of the heating plates is set to around 250°C to 450°C, and the pressure between the heating plates is set to 20 kg / cm². 2 ~300 kg / cm 2 The need to increase the temperature to a certain level is increasing. As a result, the requirements for heat resistance and durability of cushioning materials used in hot press molding are also rising.

[0052] The cushioning material for hot press molding according to the embodiment of the present invention, by including the felt material described above, not only has high cushioning properties but also higher heat resistance and durability than conventional products, and can therefore fully meet such requirements.

[0053] <Method for manufacturing felt material> A method for manufacturing felt material according to an embodiment of the present invention, in a preferred embodiment, includes the following steps (a) and (b) in this order. (a) A step of arranging a fiber web made of bat fibers on at least one surface of a substrate layer. (b) A step of forming a butt fiber layer by intertwining the fiber web and the base layer with each other.

[0054] In a method for manufacturing felt material according to an embodiment of the present invention, at least one of the base material layers is a heat-resistant base material layer containing at least one fiber selected from the group consisting of polyphenylene oxadiazole fibers and polyoxadiazole fibers.

[0055] Details and preferred embodiments of the base material layer, butt fibers, fiber web, and butt fiber layer used in the method for manufacturing felt material according to embodiments of the present invention are the same as those described above.

[0056] The method for manufacturing felt material according to the embodiment of the present invention may be modified as appropriate depending on the specific form of felt material to be manufactured. For example, if the material includes multiple butt fiber layers, the fiber web used in step (b) above may be one in which multiple fiber webs have been intertwined with each other to form a laminate of multiple butt fiber layers in advance. Alternatively, in step (b) above, after the fiber web and the base layer have been intertwined with each other, another fiber web may be intertwined with the aforementioned fiber web to form a laminate of butt fiber layers. [Examples]

[0057] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0058] [Example 1] (Formation of the base layer) A base layer (heat-resistant base layer) was formed by weaving spun yarn of poly(m-phenylene)(p-phenylene) oxadiazole fiber (POD fiber) (product name: PODRUN; manufactured by Jiangsu Pod New Material Co., Ltd.) in a plain weave. The thickness of the base layer is 0.4 mm, and the basis weight is 100 g / m 2 That was the case.

[0059] (Formation of the bat fiber layer and creation of felt material) The felt material of Example 1 was created by stacking three layers of the base material created above, laminating a fiber web (fiber length: 51mm~76mm; fineness: 2.2dtex~6.7dtex) made of poly(m-phenylene)(p-phenylene) oxadiazole fiber (POD fiber) (product name: PODRUN; manufactured by Jiangsu Pod New Material Co., Ltd.) on both sides, and then forming a butt fiber layer by needle punching. The butt fiber layer formed on both sides of the three stacked base material layers each had a thickness of 2mm and a basis weight of 500g / m². 2 That was the case.

[0060] The layer structure of the felt material obtained in Example 1 was as follows. This layer structure of the felt material is schematically shown in Figure 7. The thickness of the felt material was 5.2 mm. Butt fiber layer (POD fiber, 2mm thick) / Heat-resistant base material layer (0.4mm thick) / Heat-resistant base material layer (0.4mm thick) / Heat-resistant base material layer (0.4mm thick) / Butt fiber layer (POD fiber, 2mm thick)

[0061] [Example 2] The felt material of Example 2 was prepared in the same manner as in Example 1, except that a fiber web made of PBO fibers (product name: Zylon; manufactured by Toyobo Co., Ltd.) was used instead of a fiber web made of POD fibers (fiber length: 38 mm to 51 mm; fineness: 1 dtex to 3.3 dtex) for forming the butt fiber layer. The butt fiber layers formed on both sides of the three-layered base material each had a thickness of 2 mm and a basis weight of 500 g / m². 2 That was the case.

[0062] The layer structure of the felt material obtained in Example 2 was as follows. This layer structure of the felt material is schematically shown in Figure 7. The thickness of the felt material was 5.2 mm. Butt fiber layer (PBO fiber, 2mm thick) / Heat-resistant base material layer (0.4mm thick) / Heat-resistant base material layer (0.4mm thick) / Heat-resistant base material layer (0.4mm thick) / Butt fiber layer (PBO fiber, 2mm thick)

[0063] [Example 3] The felt material of Example 3 was prepared in the same manner as in Example 1, except that a fiber web made of PI fibers (product name: YILUN POLYIMIDE FIBER; manufactured by CHANGCHUN HIPOLYKING Co., Ltd.) (fiber length: 64 mm; fineness: 6.7 dtex) was used instead of a fiber web made of POD fibers for the formation of the butt fiber layer. The butt fiber layers formed on both sides of the three-layered base material each had a thickness of 2 mm and a basis weight of 500 g / m². 2 That was the case.

[0064] The layer structure of the felt material obtained in Example 3 was as follows. This layer structure of the felt material is schematically shown in Figure 7. The thickness of the felt material was 5.2 mm. Butt fiber layer (PI fiber, 2mm thick) / Heat-resistant base material layer (0.4mm thick) / Heat-resistant base material layer (0.4mm thick) / Heat-resistant base material layer (0.4mm thick) / Butt fiber layer (PI fiber, 2mm thick)

[0065] [Comparative Example 1] (Formation of the base layer) A base layer was formed by weaving spun yarn made from PBO fiber (product name: Zylon; manufactured by Toyobo Co., Ltd.). The thickness of the base layer was 0.3 mm, and the basis weight was 100 g / m². 2 That was the case.

[0066] (Formation of the bat fiber layer and creation of felt material) Comparative Example 1 felt material was created by stacking three of the base layers prepared above, laminating a fiber web (fiber length: 44 mm; fineness: 1.7 dtex) made of PBO fibers (product name: Zylon; manufactured by Toyobo Co., Ltd.) on both sides, and then forming a butt fiber layer by needle punching. The butt fiber layers formed on both sides of the three stacked base layers each had a thickness of 1.7 mm and a basis weight of 500 g / m². 2 That was the case.

[0067] The layer structure of the felt material obtained in Comparative Example 1 was as follows. The thickness of the felt material was 4.3 mm. Butt fiber layer (PBO fiber, 1.7 mm thick) / Base layer (PBO fiber, 0.3 mm thick) / Base layer (PBO fiber, 0.3 mm thick) / Base layer (PBO fiber, 0.3 mm thick) / Butt fiber layer (PBO fiber, 1.7 mm thick)

[0068] [Comparative Example 2] (Formation of the base layer) A base layer was formed by weaving spun yarn made from meta-aramid fibers (product name: Conex; manufactured by Teijin Limited). The thickness of the base layer was 0.4 mm, and the basis weight was 100 g / m². 2 That was the case.

[0069] (Formation of the bat fiber layer and creation of felt material) Comparative Example 2 felt material was created by stacking three of the base material layers prepared above and forming butt fiber layers similar to those formed in Comparative Example 1 on both sides of the stacked base material layers. The butt fiber layers formed on both sides of the three stacked base material layers each had a thickness of 1.7 mm and a basis weight of 500 g / m². 2 That was the case.

[0070] The layer structure of the felt material obtained in Comparative Example 2 was as follows. The thickness of the felt material was 4.6 mm. Butt fiber layer (PBO fiber, 1.7mm thick) / Base layer (meta-aramid fiber, 0.4mm thick) / Base layer (meta-aramid fiber, 0.4mm thick) / Base layer (meta-aramid fiber, 0.4mm thick) / Butt fiber layer (PBO fiber, 1.7mm thick)

[0071] <Evaluation of longitudinal cutting strength> The longitudinal cutting strength of each felt material obtained in the above-described examples and comparative examples was evaluated according to the following procedure. In this specification, the "vertical" direction of the felt material and the "vertical" direction in the vertical cutting strength refer to the direction parallel to the direction in which the heat-resistant base material layer, etc., is moved by needle punching to attach the butt fiber layer when manufacturing the felt materials of the examples and comparative examples.

[0072] A felt material (25 cm x 25 cm) was heated under the following conditions. After heating, the felt material was cut into pieces measuring 25 cm in length and 2 cm in width, so that the vertical direction was the length direction, to obtain test specimens. The obtained test specimens were pulled in the length direction under the following conditions, and the longitudinal cutting strength (N / 2 cm) after heating was measured. A test specimen was obtained by cutting a piece of unheated felt material to a length of 25 cm x 2 cm, with the longitudinal direction being the length direction. The obtained test specimen was pulled in the length direction under the following conditions, and the longitudinal cutting strength (N / 2 cm) before heating was measured. The percentage of longitudinal cutting strength retention was calculated as follows. The results are shown in Table 1. Longitudinal cutting strength retention rate = (Longitudinal cutting strength after heating / Longitudinal cutting strength before heating) × 100

[0073] [Heating conditions for felt material] • Heating temperature: 330°C and 400°C (dry heat exposure) • Heating time: 20 hours • Heating device: Asahi Kagaku Co., Ltd. High-Temp Oven H-80

[0074] [Test conditions] • Test temperature: Room temperature • Tensile speed: 100 mm / min • Measuring device: Shimadzu Corporation Autograph

[0075] <Evaluation of transverse cutting strength> The transverse cutting strength of each felt material obtained in the examples and comparative examples was evaluated using the following method. In this specification, the "lateral" direction of the felt material and the "lateral" direction in the lateral cutting strength refer to the direction perpendicular to and on the same plane as the direction in which the heat-resistant base material layer, etc., is moved to attach the butt fiber layer by needle punching when manufacturing the felt materials of the examples and comparative examples.

[0076] A 25cm x 25cm piece of felt was heated under the following conditions. After heating, the felt was cut into 25cm x 2cm pieces so that the horizontal direction was the length direction, and test specimens were obtained. The obtained test specimens were pulled in the length direction under the following conditions, and the transverse cutting strength (N / 2cm) after heating was measured. A test specimen was obtained by cutting a piece of unheated felt material to a length of 25 cm x 2 cm, with the transverse direction being the length direction. The obtained test specimen was pulled in the length direction under the following conditions, and the transverse cutting strength (N / 2 cm) before heating was measured. The lateral cutting strength retention rate (%) was determined as follows. The results are shown in Table 1. Retention rate of lateral cutting strength = (lateral cutting strength after heating / lateral cutting strength before heating) × 100

[0077] [Heating conditions for felt material] • Heating temperature: 330°C and 400°C (dry heat exposure) • Heating time: 20 hours • Heating device: Asahi Kagaku Co., Ltd. High-Temp Oven H-80

[0078] [Test conditions] • Test temperature: Room temperature • Tensile speed: 100 mm / min • Measuring device: Shimadzu Corporation Autograph

[0079] [Table 1]

[0080] As shown in Table 1, the felt materials of Examples 1 to 3 exhibited high heat resistance and durability. Such felt materials with high heat resistance and durability can be suitably used, for example, as cushioning materials for hot press molding, as well as sealing materials, spacers, and gaskets for high-temperature furnaces. In contrast, the felt materials used in Comparative Examples 1 and 2 showed inferior heat resistance and durability.

[0081] Although preferred embodiments of the present invention have been described in detail above with reference to the attached drawings, the present invention is not limited to these examples. It is clear to any person with ordinary skill in the art to which the present invention belongs that various modifications or alterations can be conceived within the scope of the technical idea described in the claims, and these are also understood to fall within the technical scope of the present invention. [Industrial applicability]

[0082] The felt material of the present invention can be used as a cushioning material for hot press molding, having higher heat resistance and durability than conventional cushioning materials for hot press molding. [Explanation of Symbols]

[0083] 1. Felt material 10 Heat-resistant base material layer 10A Additional substrate layer 20, 20A Butt fiber layer 100 hot plate 200 Mirror plate 300 laminated board 301 Prepreg 302 Metal foil 400 Cushioning material for hot press molding

Claims

1. It comprises a base layer and a butt fiber layer, At least one of the base layers is a heat-resistant base material, which is a felt material containing at least one fiber selected from the group consisting of polyphenylene oxadiazole fibers and polyoxadiazole fibers. A cushioning material for hot press molding, wherein the butt fiber layer contains at least one fiber selected from the group consisting of polyphenylene oxadiazole fiber, polyoxadiazole fiber, polyparaphenylene benzobisoxazole fiber, polyimide fiber, aramid fiber, and polyphenylene sulfide fiber.

2. The cushion material for heat press molding according to Claim 1, wherein the thickness of the felt material is 1 to 10 mm.

3. At least one of the aforementioned substrate layers has a basis weight of 50 to 500 g / m². ２ The cushioning material for heat press molding according to claim 1.

4. The said base layer includes an additional base layer, The additional base material layer does not contain either polyphenylene oxadiazole fibers or polyoxadiazole fibers, as described in claim 1, for use as a heat-press molding cushion material.

5. The cushioning material for hot press molding according to claim 4, wherein the additional base material layer comprises at least one fiber selected from the group consisting of aramid fibers, poly(p-phenylenebenzobisoxazole) fibers, polyimide fibers, fluorine fibers, glass fibers, and polyphenylene sulfide fibers.

6. A method for manufacturing a cushion material for hot press molding according to any one of claims 1 to 5, comprising the following steps (a) and (b) in this order. (a) A step of arranging a fiber web made of bat fibers on at least one surface of the base material layer. (b) A step of forming the butt fiber layer by intertwining the fiber web and the base material layer with each other.

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