Cushioning material for hot press

Abstract

To provide a cushioning material for hot press which has a simpler structure than a prior art, and can uniformly impart pressure.SOLUTION: A cushioning material for hot press has such a structure that one or more fiber layers and one or more elastic layers are stacked. In a plane facing a hot press object, a high compressive region and a low compressive region corresponding to a surface shape of the hot press object are provided. Compressive stress of the high compressive region is lower than compressive stress of the low compressive region by 10% or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a cushioning material for hot pressing. [Background technology]

[0002] Printed circuit boards, such as copper-clad laminates and flexible printed circuit boards (hereinafter referred to as FPCs), which are widely used in various electronic devices, as well as architectural and aircraft materials, such as decorative panels and honeycomb boards, are generally processed and formed by heat pressing or thermocompression bonding. For example, in the manufacture of FPCs, heat pressing or thermocompression bonding is used to attach a protective film to the surface of a resin layer, etc.

[0003] In heat press processing, the object to be heat pressed is sandwiched between the heat press platens of a heat press device and a constant pressure and heat are applied. In order to obtain a molded product with high precision, it is necessary to apply a uniform pressure to the object to be heat pressed.

[0004] However, the above-mentioned hot press processing has a problem in that the pressure may be uneven depending on the shape of the object to be hot pressed, and the pressure from the hot press platen may not be applied uniformly, resulting in poor accuracy of the press processing.

[0005] For this reason, Patent Document 1 discloses a press apparatus. The press apparatus includes a plurality of divided mounting members on which an object to be pressed is placed, a plurality of hydraulic cylinders for raising and lowering each mounting member, and a control unit that independently controls each of the plurality of hydraulic cylinders or each of the plurality of groups into which the hydraulic cylinders are divided. With this press apparatus, the object to be pressed is placed on the plurality of divided mounting members, and while the object to be pressed is held down by a press platen, the control unit controls the elevation and lowering of the divided mounting members using the plurality of hydraulic cylinders, thereby applying a uniform pressure to the object to be pressed, thereby enabling the object to be processed with high precision. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6510869 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the press device of Patent Document 1 requires a mounting member divided into a plurality of pieces and a plurality of hydraulic cylinders for raising and lowering each mounting member, resulting in a complex structure and a high cost for the device.

[0008] The present invention provides a cushioning material for hot press, which has a simpler structure than conventional techniques and is capable of applying pressure uniformly. [Means for solving the problem]

[0009] The present invention provides a cushioning material for hot pressing, which is configured by laminating one or more fiber layers and one or more elastic layers. The cushioning material for hot pressing has, on the surface facing the object to be hot pressed, high-compressibility regions and low-compressibility regions that correspond to the surface shape of the object to be hot pressed. The compressive stress of the high-compressibility regions is 10% or more lower than the compressive stress of the low-compressibility regions. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a cushioning material for hot press which has a simpler structure than the prior art and is capable of applying pressure uniformly. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing an example of a cushioning material for hot press according to the first embodiment. [Figure 2] FIG. 2 is a diagram showing an example of the cushioning material for hot press according to the first embodiment. [Figure 3] FIG. 3 is a diagram for explaining the function of the cushioning material for hot press according to the first embodiment. [Figure 4]FIG. 4 is a diagram showing an example of a cushioning material for hot press according to the second embodiment. [Figure 5] FIG. 5 is a diagram showing an example of a cushioning material for hot press according to the second embodiment. [Figure 6] FIG. 6 is a diagram showing an example of a cushioning material for hot press according to the second embodiment. [Figure 7] FIG. 7 is a diagram showing an example of a layer in which through holes are formed. [Figure 8] FIG. 8 is a diagram showing an example of a layer in which blind holes are formed. [Figure 9] FIG. 9 is a diagram showing an example of a highly compressible region. [Figure 10] FIG. 10 is a diagram showing an example of a cushioning material for hot press according to the third embodiment. [Figure 11] FIG. 11 is a diagram showing an example of a cushioning material for hot press according to the third embodiment. [Figure 12] FIG. 12 is a diagram showing an example of a cushioning material for hot press according to the fourth embodiment. [Figure 13] FIG. 13 is a diagram for explaining the details of the press test. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following description. Furthermore, various modifications and improvements can be made to the embodiments, and such modifications and improvements can also be included in the present invention.

[0013] First Embodiment The cushioning material for hot press according to the first embodiment has a layer structure in which one or more fiber layers and one or more elastic layers are laminated. The cushioning material for hot press has, in the surface facing the object to be hot-pressed, a high-compressibility region and a low-compressibility region that correspond to the surface shape of the object to be hot-pressed. The compressive stress of the high-compressibility region is 10% or more lower than the compressive stress of the low-compressibility region.

[0014] The material constituting the fiber layer can be, for example, a fiber sheet made of one or a combination of two or more materials selected from the group consisting of woven fabric, nonwoven fabric, and composite fabric of woven fabric and nonwoven fabric. The weave of the woven fabric is not particularly limited, and examples thereof include plain weave, twill weave, satin weave, and multiple weaves thereof. The fibers constituting the woven fabric can be, for example, one or a combination of two or more materials selected from the group consisting of filament yarn, spun yarn, blended yarn, blended fiber yarn, composite yarn, and covered yarn. The material constituting the fiber layer can be selected depending on the heat pressing conditions, and examples thereof include one or a combination of two or more materials selected from the group consisting of glass fiber, carbon fiber, ceramic fiber, polyester fiber, aramid fiber, and polybenzoxazole (PBO) fiber.

[0015] The material constituting the elastic layer can be one or a combination of two selected from the group consisting of rubber and resin. The elastic layer may be a laminate of a rubber layer and a resin layer. In this case, the number and order of layers are not particularly limited.

[0016] Known rubbers can be used and can be selected depending on the conditions of the hot press. Examples of rubbers include one or a mixture of two or more selected from the group consisting of fluororubber, silicone rubber, ethylene propylene rubber (EPDM), acrylonitrile butadiene rubber, styrene butadiene rubber, and urethane rubber. When a mixture is used, the combination and ratio thereof can be selected as desired depending on the purpose.

[0017] Known resins can be used and can be selected depending on the heat pressing conditions. Examples of resins include one or a mixture of two or more selected from the group consisting of phenolic resin, epoxy resin, polyimide resin, melamine resin, unsaturated polyester resin, thermosetting acrylic resin, furan resin, urea resin, and polyurethane resin. When a mixture is used, the combination and ratio thereof can be selected as desired depending on the purpose.

[0018] The hot press buffer material may optionally include an adhesive layer interposed between the fiber layer and the elastic layer to bond them together. Known adhesive materials capable of withstanding the heat from the hot press platen can be used as the adhesive layer. Examples of the adhesive material include rubber and resin. Examples of rubber include one or a mixture of two or more materials selected from the group consisting of fluororubber, silicone rubber, ethylene propylene rubber (EPDM), acrylonitrile butadiene rubber, styrene butadiene rubber, and urethane rubber. Examples of resin include one or a mixture of two or more materials selected from the group consisting of fluororesin, phenolic resin, epoxy resin, polyimide resin, melamine resin, unsaturated polyester resin, thermosetting acrylic resin, furan resin, urea resin, polyurethane resin, and inorganic adhesives such as ceramic adhesives. When a mixture is used, the combination and ratio of materials can be selected as desired depending on the purpose.

[0019] The hot press buffer material has a layer structure in which one or more fiber layers and one or more elastic layers are laminated. The order in which the fiber layers and elastic layers are laminated is not particularly limited. If necessary, the hot press buffer material may include an adhesive layer between the fiber layer and the elastic layer to bond the fiber layer and the elastic layer. Furthermore, the hot press buffer material may adhere the fiber layer and the elastic layer by impregnating the fiber layer with an adhesive. For example, a heat-curing silicone adhesive can be used as the adhesive.

[0020] The heat-press cushioning material has a high-compressibility region and a low-compressibility region on the surface facing the heat-press object, corresponding to the surface shape of the heat-press object. The surface of the heat-press cushioning material facing the heat-press object is the surface that contacts the heat-press object, or the surface that faces the heat-press object via a release sheet or the like. (a) in FIG. 1 is a cross-sectional view showing a configuration in which a heat-press cushioning material 1 and a heat-press object 2 according to a first embodiment are arranged between a pair of heat-press platens of a heat press machine. (b) in FIG. 1 is a perspective view of the heat-press cushioning material 1 and the heat-press object 2 shown in (a) in FIG. 1. As shown in FIG. 1, a lower heat-press platen 3a and an upper heat-press platen 3b of the heat press machine are arranged opposite each other, and the heat-press cushioning material 1 and the heat-press object 2 are arranged between the lower heat-press platen 3a and the upper heat-press platen 3b. For example, the hot-press cushioning material 1 is positioned on the upper hot-press platen 3b side, and the hot-press object 2 is positioned on the lower hot-press platen 3a side, with the surface shape of the hot-press object 2, such as a convex portion, facing the hot-press cushioning material 1. In this arrangement of the hot-press cushioning material 1 and the hot-press object 2, the area within the surface of the hot-press cushioning material 1 facing the hot-press object 2 that faces the convex portion of the hot-press object 2 is designated as a high-compressibility area HA, and the other area is designated as a low-compressibility area LA.

[0021] 2(a) is a cross-sectional view showing another embodiment in which the cushioning material for hot press 1 and the object to be hot-pressed 2 according to the first embodiment are arranged between a pair of heat press platens of a heat press machine. FIG. 2(b) is a perspective view of the cushioning material for hot press 1 and the object to be hot-pressed 2 shown in FIG. 2(a). Note that in FIG. 2, the same components as those in FIG. 1 are designated by the same reference numerals and will not be described further. As shown in FIG. 2, the area facing the convex portion of the object to be hot-pressed 2 and the surrounding area can be designated as a high-compressibility area HA, and the remaining area can be designated as a low-compressibility area LA. In this case, it is preferable that the area facing the convex portion of the object to be hot-pressed 2 and the area within 5 mm of the convex portion can be designated as a high-compressibility area HA, and the remaining area can be designated as a low-compressibility area LA.

[0022] The shape of the convex portions of the heat-pressed object is not limited to the shapes shown in Figures 1 and 2 and can be any shape. For example, the convex portions of the heat-pressed object can be polygonal shapes such as cubes and rectangular parallelepipeds, as well as hemispheres. The heat-pressed object may also have two or more convex portions. Examples of such heat-pressed objects include those with uneven shapes, such as FPCs. In this case, the heat-pressing cushioning material can have a number of highly compressible regions HA corresponding to the number of convex portions of the heat-pressed object.

[0023] The compressive stress of the high-compressibility region is 10% or more lower than the compressive stress of the low-compressibility region. When the compressive stress of the high-compressibility region is 10% or more lower than the compressive stress of the low-compressibility region, the cushioning material for hot press can exhibit good cushioning properties for the protrusions of the object to be hot-pressed.

[0024] The thickness of the hot press cushioning material may be different between the high compressibility area and the low compressibility area.

[0025] The ends of the hot-press cushioning material are preferably low-compressibility regions, in order to prevent the ends of the hot-press cushioning material from expanding laterally when pressure is applied to the hot-press cushioning material, thereby preventing a decrease in pressure.

[0026] The function of the heat-press cushioning material shown in FIG. 1 will be explained with reference to FIGS. 3(a) to 3(c). As shown in FIG. 3(a), the lower and upper heat-press plates 3a and 3b of a heat press machine are arranged facing each other. The heat-press object 2 and the heat-press cushioning material 1 are placed between the lower and upper heat-press plates 3a and 3b, in this order, starting from the lower heat-press platen 3a. The heat-press cushioning material 1 is positioned so that its high-compressibility region HA faces the convex portion of the heat-press object 2. When the heat-press object 2 is heated and pressed to a desired temperature by the lower and upper heat-press plates 3a and 3b in this state, the convex portion of the heat-press object 2 first comes into contact with the high-compressibility region HA of the heat-press cushioning material 1. Because the high-compressibility region HA of the heat-press cushioning material 1 has a lower compressive stress than the low-compressibility region LA, it easily deforms to fit the shape of the convex portion of the heat-press object 2, as shown in FIG. 3(b). For this reason, in the early stages of pressurization, almost no pressure is applied from the heat press platen 3 to the convex portions of the heat press object 2. As pressurization progresses, as shown in Figure 3(c), the high compressibility region HA further deforms to fit the convex portions of the heat press object 2, and at the same time, the low compressibility region LA abuts against the surfaces of the heat press object 2 other than the convex portions. In other words, because the surface of the heat press cushioning material 1 abuts against the entire surface of the heat press object 2, pressure from the heat press platen 3 can be applied uniformly to the heat press object 2 via the high compressibility region HA and the low compressibility region LA. Although not shown, a release sheet or the like may be interposed between the heat press cushioning material 1 and the heat press object 2, so that the heat press cushioning material 1 faces the heat press object 2 via the release sheet or the like.

[0027] Therefore, it is possible to provide a cushioning material for hot pressing that has a simpler structure than conventional technology and is capable of applying uniform pressure to hot pressing objects of various shapes, for example, even objects with small surface areas.

[0028] Further embodiments of the cushioning material for hot press will be described below.

[0029] <Second embodiment> The cushioning material for hot press according to the second embodiment has a layered structure in which one or more fiber layers and one or more elastic layers are laminated. The cushioning material for hot press has, in the surface facing the object to be hot pressed, a high compressibility region and a low compressibility region that correspond to the surface shape of the object to be hot pressed. The compressive stress of the high compressibility region is 10% or more lower than the compressive stress of the low compressibility region. The porosity of the high compressibility region is 1% or more higher than the porosity of the low compressibility region.

[0030] The porosity of the high-compressibility region is preferably at least 1% higher than that of the low-compressibility region. In this specification, "voids" refers to spaces formed between fibers constituting the fiber layer, or spaces formed in the pores when the elastic body constituting the elastic layer is porous. By having such a structure, the hot-press cushioning material can reduce the compressive stress of the high-compressibility region by 10% or more compared to the compressive stress of the low-compressibility region. Therefore, it has a simpler structure than conventional technology and is capable of uniformly transmitting pressure to hot-press objects of various shapes. The porosity of the high-compressibility region and the low-compressibility region can be calculated using the following formula (1), respectively.

[0031]

number

[0032] Here, Va is the volume of each region, Vf is the true volume of the fiber layer that constitutes each region, and Ve is the true volume of the elastic layer that constitutes each region. The volume Va of each region is, for example, calculated by dividing the area of ​​each region by s and the maximum thickness of the hot press cushioning material by t. max Then, it can be calculated by the following formula (2).

[0033] Va=s×t max ···(2) True volume refers to the volume of the material itself that makes up the layer. The true volume Vf of a fiber layer is calculated by dividing the weight of the fiber layer by the specific gravity of the fibers that make up the fiber layer. The specific gravity of the fibers that make up the fiber layer is determined by the method specified in JIS L 1013 and JIS L 1015. The true volume Ve of an elastic layer is calculated by dividing the weight of the elastic layer by the specific gravity of the elastic body that makes up the elastic layer. The specific gravity of the elastic body that makes up the elastic layer is determined by the method specified in JIS K 6268.

[0034] With the hot-press cushioning material 1 having such a configuration, the compressive stress in the high-compressibility region can be made 10% or more lower than the compressive stress in the low-compressibility region. Therefore, the hot-press cushioning material has a simpler structure than conventional techniques and can apply uniform pressure to hot-press objects of various shapes.

[0035] FIG. 4 is a cross-sectional view schematically showing an example of the cushioning material for hot press 1 according to the second embodiment.

[0036] The hot press cushioning material 1 of the second embodiment has a layer structure in which a first fiber layer 411, a second fiber layer 42, and a first fiber layer 412 are arranged in this order, and an elastic layer 51 is interposed between the first fiber layer 411 and the second fiber layer 42, and an elastic layer 52 is interposed between the second fiber layer 42 and the first fiber layer 412.

[0037] The second fiber layer 42 includes a first fiber sheet 42H that constitutes the high compressibility region HA and a second fiber sheet 42L that constitutes the low compressibility region LA. The porosity of the first fiber sheet 42H is preferably higher than that of the second fiber sheet 42L. The porosity of the first fiber sheet 42H and the second fiber sheet 42L can be adjusted by adjusting the weave, thickness, and thickness of the fibers constituting the woven fabric of each fiber sheet. By configuring the second fiber layer 42 in this way, the porosity of the high compressibility region HA can be made 1% or more higher than that of the low compressibility region LA.

[0038] The hot press cushioning material according to the second embodiment shown in FIG. 4 can be manufactured, for example, by the following method. First, first and second fiber sheets 42H and 42L constituting the second fiber layer 42 are prepared. Here, the porosity of the first fiber sheet 42H is higher than the porosity of the second fiber sheet 42L. A hole is formed by cutting out a portion of the second fiber sheet 42L corresponding to the high compressibility region HA. A first fiber sheet 42H having the same shape as the hole is fitted into the hole to form the second fiber layer 42. Next, two first fiber layers 411 and 412 and two elastic layers 51 and 52 are prepared. The first fiber layer 411, the second fiber layer 42, and the first fiber layer 412 are arranged in this order, and the elastic layer 51 is interposed between the first fiber layer 411 and the second fiber layer 42, and the elastic layer 52 is interposed between the second fiber layer 42 and the first fiber layer 412 to form a laminate. The laminate is subjected to a thermocompression treatment and then subjected to external processing to obtain the hot press cushioning material shown in FIG.

[0039] FIG. 5 is a cross-sectional view schematically showing another example of the cushioning material for hot press 1 according to the second embodiment.

[0040] As shown in FIG. 5, the hot press cushioning material 1 has a laminated structure in which a fiber layer 4 is interposed between two elastic layers 51 and 52.

[0041] The two elastic layers 51, 52 each comprise a first elastic sheet 5H constituting the high-compressibility region HA and a second elastic sheet 5L constituting the low-compressibility region LA. The first elastic sheet 5H is made of a porous elastic material. The second elastic sheet 5L is made of a porous or non-porous elastic material. The porosity of the first elastic sheet 5H is preferably higher than that of the second elastic sheet 5L. The porosity of the elastic sheets 5H, 5L can be adjusted by using, as each elastic sheet, a material in which an expanded or unexpanded balloon is mixed and dispersed in an elastic material, or a material in which a foaming agent or the like is mixed and foamed. By making the porosity of the first elastic sheet 5H higher than that of the second elastic sheet 5L, the porosity of the high-compressibility region HA can be increased by 1% or more compared to the porosity of the low-compressibility region LA. In addition, only one of the elastic layers on the side facing the object to be heat-pressed may be structured to include a first elastic sheet 5H that constitutes the high-compressibility region HA and a second elastic sheet 5L that constitutes the low-compressibility region LA.

[0042] The hot-press cushioning material 1 shown in FIG. 5 can be manufactured, for example, by the following method. First, first and second elastic sheets 5H and 5L, which respectively constitute the elastic layers 51 and 52, are prepared. Here, the porosity of the first elastic sheet 5H is higher than that of the second elastic sheet 5L. Holes are formed by cutting out portions of the second elastic sheet 5L corresponding to the highly compressible regions HA. The first elastic sheet 5H, which has the same shape as the holes, is fitted into the holes to form the elastic layers 51 and 52. Next, a fiber layer 4 is interposed between the elastic layers 51 and 52 to form a laminate. The laminate is subjected to a thermocompression bonding process and external shaping to obtain the hot-press cushioning material 1 shown in FIG. 5.

[0043] FIG. 6 is a cross-sectional view schematically showing another example of the cushioning material for hot press 1 according to the second embodiment.

[0044] The hot-press cushioning material 1 according to the second embodiment has a five-layer structure in which a first fiber layer 411, a second fiber layer 42, and a first fiber layer 412 are arranged in this order, with an elastic layer 51 interposed between the first fiber layer 411 and the second fiber layer 42, and an elastic layer 52 interposed between the second fiber layer 42 and the first fiber layer 412. The highly compressible region HA of the hot-press cushioning material 1 does not have the second fiber layer 42, and the elastic layers 51 and 52 are in contact with each other.

[0045] The thickness and porosity of the elastic layers 51, 52 are substantially the same in the high compressibility region HA and the low compressibility region LA. The total thickness of the fiber layers is substantially the same in the high compressibility region HA and the low compressibility region LA. That is, the total thickness of the portion of the first fiber layers 411, 412 corresponding to the high compressibility region HA is substantially the same as the total thickness of the portion of the first fiber layers 411, 412 corresponding to the low compressibility region LA and the second fiber layer 42.

[0046] The portions of the first fiber layers 411, 412 corresponding to the low compressibility regions LA are compressed in accordance with the thickness of the second fiber layer 42. Alternatively, an elastic layer (if the hot-press cushioning material 1 has an adhesive layer, at least one of the elastic layer and the adhesive layer) is inserted into the side of the first fiber layers 411, 412 facing the elastic layer in accordance with the thickness of the second fiber layer 42. Alternatively, the portions of the first fiber layers 411, 412 corresponding to the low compressibility regions LA are compressed in accordance with the thickness of the second fiber layer 42, and an elastic layer (if the hot-press cushioning material 1 has an adhesive layer, at least one of the elastic layer and the adhesive layer) is inserted into the side of the first fiber layers 411, 412 facing the elastic layer in accordance with the thickness of the second fiber layer 42. Therefore, the porosity of the portions of the first fiber layers 411, 412 corresponding to the low compressibility regions LA is smaller than that of the portions corresponding to the high compressibility regions HA. The porosity of the second fiber layer 42 is smaller than that of the portions of the first fiber layers 411 and 412 corresponding to the highly compressible regions HA. Thus, the highly compressible regions HA have a higher porosity than the less compressible regions LA.

[0047] In the manufacturing method of the hot press cushioning material 1 described below, by adjusting the shape and depth of the through holes, the physical properties of the fiber layer and elastic layer that make up the hot press cushioning material, and the thermocompression processing conditions, the porosity of the high compressibility region HA can be made 1% or more higher than the porosity of the low compressibility region LA.

[0048] The hot press cushioning material 1 shown in FIG. 6 can be manufactured, for example, by the following method. First, a fiber sheet that will form the second fiber layer 42 is prepared. A portion of the fiber sheet corresponding to the highly compressible region HA is cut out to form a through hole, thereby producing the second fiber layer 42. Next, two first fiber layers 411, 412 and two elastic layers 51, 52 are prepared. The first fiber layer 411, the second fiber layer 42, and the first fiber layer 412 are arranged in this order, and the elastic layer 51 is interposed between the first fiber layer 411 and the second fiber layer 42, and the elastic layer 52 is interposed between the second fiber layer 42 and the first fiber layer 412 to form a laminate. The laminate is then subjected to a thermocompression bonding process to bond the laminate. By adjusting the shape and depth of the through-hole, the physical properties of the fiber layers and elastic layers constituting the hot-press buffer material, and the conditions of the hot-press bonding process, the elastic layers 51 and 52 located above and below the through-hole in the thickness direction are deformed so that they come into contact with each other during the hot-press bonding process, and the through-hole is blocked by the elastic layers 51 and 52. At this time, the portion of the first fiber layers 411 and 412 corresponding to the low-compressibility region LA is compressed according to the thickness of the second fiber layer 42. Alternatively, the elastic layer (or at least one of the elastic layer and the adhesive layer, if the hot-press buffer material 1 has an adhesive layer) penetrates into the side of the portion facing the elastic layer. Alternatively, both the compression of the first fiber layer and the penetration of the elastic layer occur. In this way, the thickness of the portion of the first fiber layers 411 and 412 corresponding to the low-compressibility region LA decreases, reducing the porosity, and the porosity of the low-compressibility region LA becomes smaller than that of the high-compressibility region HA. In this way, the high-compressibility region HA and the low-compressibility region LA are formed in the laminate. The laminate in which the high compressibility region HA and the low compressibility region LA are formed is subjected to outer shaping to obtain the cushioning material for hot press shown in FIG.

[0049] <Third embodiment> The hot-press cushioning material according to the third embodiment has a layered structure in which one or more fiber layers and one or more elastic layers are laminated. The hot-press cushioning material has, in the surface facing the hot-press object, a high-compressibility region and a low-compressibility region that correspond to the surface shape of the hot-press object. The compressive stress of the high-compressibility region is 10% or more lower than the compressive stress of the low-compressibility region. The hot-press cushioning material has three or more layers. The hot-press cushioning material has at least one of through holes, blind holes, and depressions in the high-compressibility region. The through holes and blind holes are formed in at least one layer other than the topmost and bottommost layers of the layer structure. The depressions are formed in at least one of the topmost and bottommost layers of the layer structure.

[0050] The hot-press cushioning material has a three-layer structure in which one or more fiber layers and one or more elastic layers are laminated. The combination of the fiber layers and the elastic layers is not particularly limited and can be any configuration.

[0051] The cushioning material for hot press has at least one of through holes, blind holes and depressions in the highly compressible region.

[0052] The through holes and blind holes are formed in at least one layer other than the top layer and the bottom layer of the layer structure.

[0053] The through holes are formed in the layer in which the through holes are formed so that the holes penetrate from top to bottom in the thickness direction. An example of a layer in which through holes are formed is shown in Fig. 7. Fig. 7(a) is a plan view, and Fig. 7(b) is a cross-sectional view taken along line AA in Fig. 7(a). In Fig. 7, the through holes 61 are formed in the layer 71 having the through holes 61 so that the holes penetrate from top to bottom in the thickness direction.

[0054] The blind holes are formed on at least one of the upper and lower sides in the thickness direction of the layer in which the blind holes are formed. An example of a layer in which blind holes are formed is shown in FIG. 8. FIG. 8(a) is a plan view, and FIG. 8(b) is a cross-sectional view taken along line BB in FIG. 8(a). In FIG. 8, the blind holes 62 are formed on the upper side in the thickness direction of the layer 72 in which the blind holes 62 are formed. Note that in FIG. 7(b) and FIG. 8(b), the layer 71 having the through holes and the layer 72 having the blind holes are shown as elastic layers as an example, but are not limited to this and may be fiber layers.

[0055] The recess is formed in at least one of the top layer and the bottom layer of the layer structure.

[0056] The shapes and positions of the through holes, blind holes and depressions can be changed depending on the surface shape of the object to be hot-pressed, for example, the shape and position of the protrusions.

[0057] The volume of the through holes, non-through holes, and depressions relative to the volume of the highly compressible region is preferably 1% or more. Here, the volume of the highly compressible region includes the volumes of the through holes, non-through holes, and depressions. The area of ​​the highly compressible region is defined as s H , the maximum thickness of the buffer material for heat pressing is t max Then, the volume of the highly compressible region Va H is calculated by the following formula (3): Figure 9 shows, as an example, a highly compressible region in which through holes or non-through holes are formed. In Figure 9, reference numeral 60 denotes the through holes or non-through holes.

[0058] Va H =s H ×t max ···(3) When at least one of the fiber layers and elastic layers constituting the high-compressibility region and the low-compressibility region of the hot-press cushioning material has voids, the same effect can be achieved by making the ratio of the total volume of voids, through holes, blind holes, and depressions in the high-compressibility region to the volume of the high-compressibility region 1% or more higher than the ratio of the volume of voids in the low-compressibility region to the volume of the low-compressibility region. The volume ratios of voids, through holes, blind holes, and depressions are not particularly limited and can be any ratio.

[0059] The total volume of voids, through holes, blind holes, and depressions in each region relative to the volume of each region can be calculated in the same manner using the above formula (1) for porosity.

[0060] This structure of the hot-press cushioning material allows the compressive stress in the high-compressibility region to be 10% or more lower than the compressive stress in the low-compressibility region, making it simpler in structure than conventional technology and capable of transmitting pressure evenly to hot-press objects of various shapes.

[0061] FIG. 10 is a cross-sectional view schematically showing an example of a cushioning material for hot press 1 according to the third embodiment.

[0062] The hot press cushioning material 1 of the third embodiment has a five-layer structure in which a first fiber layer 411, a second fiber layer 42, and a first fiber layer 412 are arranged in this order, with an elastic layer 51 interposed between the first fiber layer 411 and the second fiber layer 42, and an elastic layer 52 interposed between the second fiber layer 42 and the first fiber layer 412.

[0063] The hot press cushioning material 1 has through holes 61 in the highly compressible region HA, and the through holes 61 are formed in the second fiber layer 42, which is one of the layers other than the top and bottom layers of the layer structure. The through holes 61 are formed so as to penetrate the second fiber layer 42 from top to bottom in the thickness direction. The volume of the through holes 61 relative to the volume of the highly compressible region is preferably 1% or more.

[0064] 11 is a cross-sectional view schematically showing another example of the cushioning material for hot press 1 according to the third embodiment. The description above is used to cite and omit the description of the same configuration as the example of the cushioning material for hot press 1 according to the third embodiment.

[0065] The hot press cushioning material 1 has through holes 61 and depressions 63 in the high compressibility region HA. The through holes 61 are formed in the second fiber layer 42, which is one of the layers other than the top and bottom layers of the layer structure. The depressions 63 are formed in the first fiber layer 412, which is the top layer of the layer structure. The depressions 63 are formed by the first fiber layer 412 and the portions of the elastic layer 52 above the through holes 61 that correspond to the high compressibility region bending toward the through holes 61. It is preferable that the total volume of the through holes 61 and depressions 63 relative to the volume of the high compressibility region HA is 1% or more.

[0066] The hot-press cushioning material 1 shown in FIG. 10 can be manufactured, for example, by the following method. First, a fiber sheet for forming the second fiber layer 42 is prepared. A portion of the fiber sheet corresponding to the highly compressible region HA is cut out to form a through-hole 61, thereby producing the second fiber layer 42. Next, two first fiber layers 411, 412 and two elastic layers 51, 52 are prepared. The first fiber layer 411, the second fiber layer 42, and the first fiber layer 412 are arranged in this order, with the elastic layer 51 interposed between the first fiber layer 411 and the second fiber layer 42, and the elastic layer 52 interposed between the second fiber layer 42 and the first fiber layer 412, respectively, to form a laminate. This forms a through-hole 61 in the second fiber layer 42. The laminate is then subjected to a thermocompression bonding process to compress the laminate. The laminate is then contoured to produce the hot-press cushioning material 1 shown in FIG. 10. In the above method, by adjusting the shape and depth of the through-hole 61, the physical properties of the fiber layers and elastic layers constituting the hot-press cushioning material, and the conditions for the thermocompression bonding process, the portions of the first fiber layer 412 and the elastic layer 52 present above the through-hole 61 that correspond to the highly compressible regions are deflected toward the through-hole 61. This forms a depression 63 in the first fiber layer 412, and the hot-press cushioning material 1 shown in FIG. 11 is obtained.

[0067] <Fourth embodiment> A cushioning material for hot press according to a fourth embodiment has a layered structure in which one or more fiber layers and one or more elastic layers are laminated. The cushioning material for hot press has, in the surface facing the object to be hot pressed, high-compressibility regions and low-compressibility regions that correspond to the surface shape of the object to be hot pressed. The compressive stress of the high-compressibility regions is 10% or more lower than the compressive stress of the low-compressibility regions. In at least one layer of the elastic layer, the hardness of the portion corresponding to the high-compressibility regions is 15 degrees or more lower than the portion corresponding to the low-compressibility regions, as measured with a Type A durometer according to JIS K6253.

[0068] In at least one layer of the elastic layer, the portion corresponding to the high compressibility region preferably has a hardness measured with a Type A durometer according to JIS K6253 that is 15 degrees or more lower than the portion corresponding to the low compressibility region.

[0069] This structure of the hot-press cushioning material allows the compressive stress in the high-compressibility region to be 10% or more lower than the compressive stress in the low-compressibility region, making it simpler in structure than conventional technology and capable of transmitting pressure evenly to hot-press objects of various shapes.

[0070] FIG. 12 is a cross-sectional view schematically showing an example of a cushioning material for hot press use 1 according to the fourth embodiment.

[0071] The hot-press cushioning material 1 according to the fourth embodiment has a structure in which two elastic layers 51 and 52 are laminated with a fiber layer 4 interposed between them.

[0072] Each of the two elastic layers 51, 52 comprises a first elastic sheet 5H constituting a portion corresponding to the high compressibility region HA and a second elastic sheet 5L constituting a portion corresponding to the low compressibility region LA. The hardness of the first elastic sheet 5H, as measured with a Type A durometer according to JIS K6253, is preferably at least 15 degrees lower than that of the second elastic sheet 5L. Note that only one of the elastic layers on the side facing the object to be hot-pressed may have the above configuration.

[0073] The hot-press cushioning material 1 shown in FIG. 12 can be manufactured, for example, as follows. First, first and second elastic sheets 5H and 5L, which respectively constitute the elastic layers 51 and 52, are prepared. Here, the hardness of the first elastic sheet 5H, measured using a Type A durometer according to JIS K6253, is at least 15 degrees lower than that of the second elastic sheet 5L. Holes are formed by cutting out portions of the second elastic sheet 5L corresponding to the highly compressible regions HA. The first elastic sheet 5H, which has the same shape as the holes, is fitted into the holes to form the elastic layers 51 and 52. Next, a fiber layer 4 is prepared, and the fiber layer 4 is interposed between the elastic layers 51 and 52 to form a laminate. The laminate is then subjected to a thermocompression bonding process and external shaping to obtain the hot-press cushioning material 1 shown in FIG. 12.

[0074] The cushioning materials for hot press according to the first to fourth embodiments described above have a layer structure in which one or more fiber layers and one or more elastic layers are laminated. The cushioning materials for hot press have, in the surface facing the object to be hot-pressed, high-compressibility regions and low-compressibility regions that correspond to the surface shape of the object to be hot-pressed. The compressive stress of the high-compressibility regions is 10% or more lower than the compressive stress of the low-compressibility regions.

[0075] The cushioning materials for hot pressing according to the first to fourth embodiments have such a configuration, and therefore have a simpler structure than conventional techniques, and are capable of applying uniform pressure to objects to be hot pressed of various shapes.

[0076] The cushioning materials for hot press according to the first to fourth embodiments can be used in, for example, a process of thermocompression bonding a protective film to a flexible printed circuit board (FPC board) on which a circuit pattern is formed.

[0077] (Example) The present invention will be described in more detail below by way of examples, but is not limited to these examples.

[0078] Example 1 The first fiber layer is aramid woven fabric (basis weight: 400 g / m2 , thickness: 0.70 mm) was prepared. A first aramid woven fabric (basis weight: 82 g / m) for producing the second fiber layer 2 , thickness: 0.19 mm) and a second aramid woven fabric (basis weight: 170 g / m 2 A second aramid woven fabric (thickness: 0.35 mm) was prepared. The center of the second aramid woven fabric was cut out to form a hole with a width of 300 mm and a depth of 300 mm. A first aramid woven fabric with a width of 300 mm and a depth of 300 mm was fitted into the hole to prepare a second fiber layer.

[0079] The raw rubber was Dyneon (registered trademark) FC-2120, the filler was carbon (Thermax N990, manufactured by Cancarb), the vulcanization aid was Kyowamag (registered trademark) 150 (manufactured by Kyowa Chemical Industry Co., Ltd.), and the vulcanization accelerator was Carbit (manufactured by Ohmi Chemical Industry Co., Ltd.). The filler, vulcanization aid, and vulcanization accelerator were dispersed in the raw rubber in a weight ratio (raw rubber:filler:vulcanization aid:vulcanization accelerator) of 100:5:3:6 to prepare a rubber compound. The resulting rubber compound was molded into a 0.20 mm thick sheet to produce a rubber layer.

[0080] A first fiber layer, a second fiber layer, and a rubber layer were laminated from the bottom in the following order: first fiber layer / rubber layer / second fiber layer / rubber layer / first fiber layer to obtain a laminate. The laminate was pressed at a temperature of 170°C and a pressure of 0.5 MPa for 30 minutes to form a molded product. The rubber layer was vulcanized by pressing to form an elastic layer. A hot-press cushioning material was produced using this method. The hot-press cushioning material had a width of 500 mm, a depth of 500 mm, and a thickness of 1.5 mm.

[0081] In the hot press cushioning material of Example 1, the central portion (width 300 mm x depth 300 mm x thickness 1.5 mm) having the first aramid woven fabric in the second fiber layer functioned as the high compressibility region HA, and the portion having the second aramid woven fabric in the second fiber layer functioned as the low compressibility region LA.

[0082] Example 2 The raw rubber X-30-4600-U (Shin-Etsu Chemical Co., Ltd.), the vulcanizing agents C-8 (Shin-Etsu Chemical Co., Ltd.) and C-23N (Shin-Etsu Chemical Co., Ltd.), the foaming agent KE-P-26 (Shin-Etsu Chemical Co., Ltd.), and the colored silicone rubber KE-color-BR (Shin-Etsu Chemical Co., Ltd.) were prepared. The vulcanizing agent, foaming agent, and colored silicone rubber were dispersed in the raw rubber at a weight ratio (X-30-4600-U:C-8:C-23N:KE-P-26:KE-color-BR) of 100:1.5:0.2:5:0.5 to prepare a rubber compound. The resulting rubber compound was molded into a 0.53 mm thick sheet to prepare an unfoamed first rubber sheet.

[0083] The raw rubber X-30-4600-U (Shin-Etsu Chemical Co., Ltd.), the vulcanizing agents C-8 (Shin-Etsu Chemical Co., Ltd.) and C-23N (Shin-Etsu Chemical Co., Ltd.), and the colored silicone rubber KE-color-BR (Shin-Etsu Chemical Co., Ltd.) were prepared. The vulcanizing agent and colored silicone rubber were dispersed in the raw rubber at a weight ratio (X-30-4600-U:C-8:C-23N:KE-color-BR) of 100:1.5:0.2:0.5 to prepare a rubber compound. The resulting rubber compound was molded into a 0.95 mm thick sheet to prepare an unfoamed second rubber sheet.

[0084] The center of the second rubber sheet was cut out to form a hole measuring 300 mm in width and 300 mm in depth. The first rubber sheet also measuring 300 mm in width and 300 mm in depth was fitted into the hole to prepare a rubber layer.

[0085] The fiber layer is aramid woven fabric (weight: 61 g / m 2A 0.14mm thick aramid woven fabric was prepared. The fabric was impregnated with TSE322 (manufactured by Momentive Performance Materials Japan, LLC) by dipping and nipping. A rubber layer and a fiber layer were layered from the bottom up in the order rubber layer / fiber layer / rubber layer to obtain a laminate. The laminate was pressed at 170°C and 0.5MPa for 30 minutes to form a molded product. The rubber layer was vulcanized and foamed by the press, forming an elastic layer. During press molding, 2.00mm thick spacers were placed around the laminate placed in the press before pressing. Using this method, a heat-press cushioning material was produced. The heat-press cushioning material had a width of 500mm, a depth of 500mm, and a thickness of 2.0mm.

[0086] In the hot press cushioning material of Example 2, the central portion (width 300 mm x depth 300 mm x thickness 2.0 mm) having the first rubber sheet in the elastic layer functioned as the high compressibility region HA, and the portion having the second rubber sheet in the elastic layer functioned as the low compressibility region LA.

[0087] Example 3 The first fiber layer is aramid woven fabric (basis weight: 400 g / m 2 , thickness: 0.70 mm) was prepared. Aramid woven fabric (basis weight: 170 g / m) for producing the second fiber layer 2 A second fiber layer was prepared by cutting out the center of the fiber sheet to form a through-hole measuring 300 mm in width and 300 mm in depth.

[0088] The rubber layer was prepared in the same manner as in Example 1.

[0089] A first fiber layer, a second fiber layer, and a rubber layer were laminated from the bottom in the following order: first fiber layer / rubber layer / second fiber layer / rubber layer / first fiber layer to obtain a laminate. The laminate was pressed at 170°C and 0.5 MPa for 30 minutes to bond the laminate. The rubber layer was vulcanized by the press to form an elastic layer. The press also deflected the first fiber layer and the elastic layer located above the through-hole in the second fiber layer toward the through-hole, forming a recess in the central 300 mm x 300 mm portion of the upper surface of the hot-press cushioning material in the thickness direction. This method was used to prepare a hot-press cushioning material. The width, depth, and thickness of the hot-press cushioning material were 500 mm, 500 mm, and 1.5 mm, respectively.

[0090] In the hot-press cushioning material of Example 3, the central portion (width 300 mm x depth 300 mm x thickness 1.5 mm) having the through-holes and recesses functioned as the high compressibility region HA, and the other portion functioned as the low compressibility region LA.

[0091] Example 4 The raw rubber was Dyneon (registered trademark) FC-2120, the filler was carbon (Thermax N990, manufactured by Cancarb), the vulcanization aid was Kyowamag (registered trademark) 150 (manufactured by Kyowa Chemical Industry Co., Ltd.), and the vulcanization accelerator was Carbit (manufactured by Ohmi Chemical Industry Co., Ltd.). The filler, vulcanization aid, and vulcanization accelerator were dispersed in the raw rubber in a weight ratio (raw rubber:filler:vulcanization aid:vulcanization accelerator) of 100:5:3:6 to prepare a rubber compound. The resulting rubber compound was molded into a sheet with a thickness of 0.60 mm to produce a first rubber sheet.

[0092] A second rubber sheet was produced in the same manner as the first rubber sheet, except that the weight ratio of raw rubber:filler:vulcanization aid:vulcanization accelerator was 100:35:3:6.

[0093] The center of the second rubber sheet was cut out to form a hole measuring 300 mm in width and 300 mm in depth. The first rubber sheet also measuring 300 mm in width and 300 mm in depth was fitted into the hole to prepare a rubber layer.

[0094] The fiber layer is aramid woven fabric (weight: 82 g / m 2 A laminate (0.19 mm thick) was prepared, and a rubber layer and a fiber layer were laminated from the bottom in the order rubber layer / fiber layer / rubber layer to obtain a laminate. The laminate was pressed at a temperature of 170°C and a pressure of 0.5 MPa for 30 minutes to form the shape. The rubber layer was vulcanized by the press to form an elastic layer. In this way, a cushioning material for hot press was produced. The width of the cushioning material for hot press was 500 mm, the depth was 500 mm, and the thickness was 1.2 mm.

[0095] In the hot press cushioning material of Example 4, the central portion (width 300 mm x depth 300 mm x thickness 1.2 mm) having the first rubber sheet in the elastic layer functioned as the high compressibility region HA, and the portion having the second rubber sheet in the elastic layer functioned as the low compressibility region LA.

[0096] The Type A durometer hardness of the first and second rubber sheets of the hot press cushioning material according to Example 4 when vulcanized to form elastomers was measured using a hardness measurement sheet. The hardness measurement sheet was prepared by pressing the first and second rubber sheets, which were prepared in the same manner as in Example 2, at a temperature of 170°C and a pressure of 0.5 MPa for 30 minutes. The Type A durometer hardness of the first rubber sheet when vulcanized to form an elastomer was 65, and the Type A durometer hardness of the second rubber sheet when vulcanized to form an elastomer was 80. The Type A durometer hardness was measured based on JIS K6253.

[0097] (Comparative Example 1) Aramid woven fabric (basis weight: 170 g / m) was used as the second fiber layer. 2 A cushioning material for hot press was produced in the same manner as in Example 1, except that a sheet of 1000 kJ / cm2 (1000 kJ / cm2, thickness: 0.35 mm) was used.

[0098] (Comparative Example 2) The raw rubber X-30-4600-U (Shin-Etsu Chemical Co., Ltd.), the vulcanizing agents C-8 (Shin-Etsu Chemical Co., Ltd.) and C-23N (Shin-Etsu Chemical Co., Ltd.), and the colored silicone rubber KE-color-BR (Shin-Etsu Chemical Co., Ltd.) were prepared. The vulcanizing agent and colored silicone rubber were dispersed in the raw rubber at a weight ratio (X-30-4600-U:C-8:C-23N:KE-color-BR) of 100:1.5:0.2:0.5 to prepare a rubber compound. The resulting rubber compound was molded into a 0.95 mm thick sheet to create the rubber layer.

[0099] A cushioning material for hot press was produced in the same manner as in Example 2, except that the above layer was used as the rubber layer.

[0100] (Comparative Example 3) The raw rubber was Dyneon (registered trademark) FC-2120, the filler was carbon (Thermax N990, manufactured by Cancarb), the vulcanization aid was Kyowamag (registered trademark) 150 (manufactured by Kyowa Chemical Industry Co., Ltd.), and the vulcanization accelerator was Carbit (manufactured by Ohmi Chemical Industry Co., Ltd.). The filler, vulcanization aid, and vulcanization accelerator were dispersed in the raw rubber in a weight ratio (raw rubber:filler:vulcanization aid:vulcanization accelerator) of 100:5:3:6 to prepare a rubber compound. The resulting rubber compound was molded into a sheet with a thickness of 0.60 mm to produce a rubber sheet.

[0101] A cushioning material for hot press was produced in the same manner as in Example 4, except that the above rubber sheet was used as the rubber layer.

[0102] The Type A durometer hardness of the rubber sheet of the hot press cushioning material according to Comparative Example 3 when vulcanized to form an elastomer was measured using a hardness measurement sheet. The hardness measurement sheet was produced in the same manner as in Example 4, except that a rubber sheet produced in the same manner as in Comparative Example 3 was used. The Type A durometer hardness of the rubber sheet of Comparative Example 3 when vulcanized to form an elastomer was 65. The Type A durometer hardness was measured based on JIS K6253.

[0103] <Calculation of void ratio> The porosity of the high compressibility region HA and the low compressibility region LA was calculated for the hot-press cushioning materials of Examples 1 and 2. The porosity of the hot-press cushioning materials of Comparative Examples 1 and 2 was also calculated. The porosity was calculated using the above formula (1). The results are shown in Tables 1 and 2.

[0104] For the hot-press cushioning materials of Examples 1 and 2, the difference in void ratio between the high compressibility region HA and the low compressibility region LA was calculated using the following formula (4). The results are shown in Tables 1 and 2.

[0105] [Void ratio difference] = [Void ratio of high compressibility region HA] - [Void ratio of low compressibility region LA] (4) <Measurement of the volume ratio of voids, through holes, and depressions> For the hot press cushioning material of Example 3, the ratio of the total volume of the voids, through-holes, and depressions in the high compressibility region HA to the volume of the high compressibility region HA was calculated. Also, the ratio of the volume of the voids in the low compressibility region LA to the volume of the low compressibility region LA was calculated, and the difference between them was calculated. The results are shown in Table 3.

[0106] <Measurement of compressive stress> The compressive stress of the cushioning materials for hot press of Examples 1 to 4 was measured by the following method. The terminal (diameter 28 mm) of a universal testing machine (Tensilon RTG-1250, manufactured by Orientec Co., Ltd.) was pressed into the low-compressibility region LA of the heat press cushioning material at a speed of 2 mm / min, while measuring the compressive stress of the low-compressibility region LA. The displacement of the low-compressibility region LA when the compressive stress reached 2 MPa (hereinafter referred to as displacement δ LA Next, the terminal of the universal testing machine was pressed into the highly compressible region HA of the hot press buffer material at a speed of 2 mm / min, and the displacement δ of the highly compressible region HA was measured. HA is the displacement δ LA The compressive stress of the highly compressible region HA was measured at the point when the displacement δ became the same as the value of the highly compressible region HA. For the cushioning material for hot press of Example 3, the compressive stress of the highly compressible region HA was measured on the surface where the depressions were formed. HA and displacement δ LAwas measured using the maximum thickness of each hot press buffer material as the reference (i.e., displacement is 0).

[0107] <Calculation of the compressive stress difference ratio> For the hot-press cushioning materials of Examples 1 to 4, the ratio of the compressive stress difference between the high-compressibility region HA and the low-compressibility region LA to the compressive stress of the low-compressibility region LA was calculated using the following formula (5). The compressive stress of the low-compressibility region LA was set to 2 MPa. The results of Examples 1 to 4 are shown in Tables 1 to 4, respectively.

[0108]

number

[0109] <Press Test> The uniformity of the heat press pressure applied by the heat press machine was evaluated using the heat press cushioning materials of Examples 1 to 4 and Comparative Examples 1 to 3. As shown in Figure 13, two heat press cushioning materials 11 and 12, a release sheet 8 (MSF-100, manufactured by Chukoh Chemical Industries, Ltd., thickness: 0.1 mm), a sheet with a central convex portion (300 mm wide x 300 mm deep) (hereinafter referred to as the heat press object 2, material: PI (polyimide)), and pressure-sensitive paper 9 (high-temperature prescale LLW, manufactured by Fujifilm) were stacked from the bottom in the order of heat press cushioning material 11 / release sheet 8 / pressure-sensitive paper 9 / heat press object 2 / release sheet 8 / heat press cushioning material 12, and placed between the lower heat press platen 3a and the upper heat press platen 3b of the heat press machine. The high compressibility region HA of the heat press cushioning material 12 was positioned facing the convex portion of the heat press object 2. Furthermore, for the test of Example 3, the heat-press buffer materials 11 and 12 were each positioned so that the side with the depressions faced the heat-press object 2. The height of the convex portion of the heat-press object 2 was 0.10 mm for the evaluations of Examples 1 and 3 and Comparative Example 1, and 0.025 mm for the evaluations of Example 4 and Comparative Example 3. For the evaluations of Example 2 and Comparative Example 2, a 0.125 mm-thick sheet film (300 mm wide x 300 mm deep, made of PI (polyimide)) was laminated on top of the convex portion of the heat-press object 2, making the overall height of the convex portion 0.75 mm. Pressing was performed using heat presses 3a and 3b at a temperature of 180°C and a pressure of 2 MPa. The discoloration density of the surface of the pressure-sensitive paper 9 was measured using a spectrodensitometer (Spectrodensitometer, manufactured by TECHKON) to evaluate the uniformity of the pressure. A difference between the maximum and minimum discoloration density values ​​within the surface of the pressure-sensitive paper 9 was judged as good if it was within 0.1 mm, and otherwise was judged as bad. The results of Examples 1 to 4 and Comparative Examples 1 to 3 are shown in Tables 1 to 4, respectively.

[0110] [Table 1]

[0111] [Table 2]

[0112] [Table 3]

[0113] [Table 4]

[0114] As is clear from Tables 1 to 4, the heat-press cushioning materials of Examples 1 to 4, which have a structure in which one or more fiber layers and one or more elastic layers are laminated, and which have high-compressibility regions and low-compressibility regions on the surface facing the heat-press object that correspond to the surface shape of the heat-press object, and in which the compressive stress of the high-compressibility regions is 10% or more lower than the compressive stress of the low-compressibility regions, can all apply pressure from the heat-press platen uniformly to the heat-press object.

[0115] In contrast, it is found that the heat-pressing cushioning materials of Comparative Examples 1 to 3, which do not have high-compressibility and low-compressibility regions corresponding to the surface shape of the heat-pressed object, are unable to apply pressure from the heat-pressing platen uniformly to the heat-pressed object.

[0116] As is clear from Tables 1 and 2, the heat press cushioning materials of Examples 1 and 2, in which the porosity of the high compressibility region HA is 1% or more higher than the porosity of the low compressibility region LA, have a compressive stress in the high compressibility region HA that is 10% or more lower than the compressive stress in the low compressibility region LA.

[0117] As is clear from Table 3, the hot press cushioning material of Example 3 has a layer structure of three or more layers, and has at least one of through holes, non-through holes, and depressions in the high compressibility region, the through holes and non-through holes being formed in at least one layer other than the topmost and bottommost layers of the layer structure, and the depressions being formed in at least one of the topmost and bottommost layers of the layer structure, and it can be seen that the compressive stress of the high compressibility region HA is 10% or more lower than the compressive stress of the low compressibility region LA.

[0118] Furthermore, as is clear from Table 4, in the hot press cushioning material of Example 4, in which the portion corresponding to the high compressibility region in at least one layer of the elastic layer has a hardness measured with a Type A durometer based on JIS K6253 that is 15 degrees or more lower than the portion corresponding to the low compressibility region, the compressive stress of the high compressibility region HA is 10% or more lower than that of the low compressibility region LA. [Explanation of symbols]

[0119] 1...heat press cushioning material, 2...heat press object, 3...heat press platen, 4...fiber layer, 5...elastic layer, 61...through hole, 62...non-through hole, 63...recess, 71...layer in which through hole is formed, 72...layer in which non-through hole is formed, 8...release sheet, 9...pressure-sensitive paper, HA...high compressibility region, LA...low compressibility region.

Claims

1. A cushioning material for hot press having a layered structure in which one or more fiber layers and one or more elastic layers are laminated, A surface facing the object to be hot-pressed is provided with a high compressibility region and a low compressibility region corresponding to the surface shape of the object to be hot-pressed, A cushioning material for hot press, wherein the compressive stress of the high compressibility region is 10% or more lower than the compressive stress of the low compressibility region.

2. 2. The cushioning material for hot press use according to claim 1, wherein the porosity of the high compressibility region is 1% or more higher than the porosity of the low compressibility region.

3. The cushioning material for hot press according to claim 2 , wherein at least one of the fiber layers constituting the high compressibility region has a higher porosity than at least one of the fiber layers constituting the low compressibility region.

4. 3. The cushioning material for hot press according to claim 2, wherein at least one of the elastic layers constituting the highly compressible region is porous.

5. Three or more layers are provided, The highly compressible region has at least one of a through hole, a blind hole, and a depression, the through holes and the blind holes are formed in at least one layer other than the top layer and the bottom layer of the layer structure, The cushioning material for hot press according to claim 1 , wherein the depression is formed in at least one of the uppermost layer and the lowermost layer of the layer structure.

6. 2. The hot press cushioning material according to claim 1, wherein in at least one layer of the elastic layer, the portion corresponding to the high compressibility region has a hardness measured with a Type A durometer according to JIS K6253 that is 15 degrees or more lower than the portion corresponding to the low compressibility region.

Images