Cushioning material for heat press

Abstract

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. [Solution] This is a cushioning material for hot pressing, which is configured by laminating one or more fiber layers and one or more elastic layers. In the surface facing the object to be hot pressed, it has 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.

Description

[Technical field]

[0001] The present invention relates to a cushioning material for hot press. [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, and building and aircraft materials such as decorative panels and honeycomb boards are generally processed and formed by heat pressing and thermocompression bonding. For example, in the manufacture of FPCs, heat pressing and thermocompression bonding are performed to attach a protective film to the resin layer surface, etc.

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

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

[0005] For this reason, Patent Document 1 discloses a press device. The press device 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 for independently controlling each of the plurality of hydraulic cylinders or each of the plurality of groups into which the plurality of hydraulic cylinders are divided. With this press device, 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 elevation and lowering of the divided mounting members is controlled by the plurality of hydraulic cylinders according to a command from the control unit. This makes it possible to apply 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 high device costs.

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

[0009] The present invention provides a cushioning material for hot press, which is configured by laminating one or more fiber layers and one or more elastic layers. The cushioning material for hot press has, in a surface facing an 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. Effect 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 description 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. [Diagram 2] FIG. 2 is a diagram showing an example of the cushioning material for hot press according to the first embodiment. [Diagram 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. [Diagram 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 a through hole is formed. [Figure 8] FIG. 8 is a diagram showing an example of a layer in which non-through 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 PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described, but the present invention is not limited to the following description. In addition, various modifications and improvements can be made to the embodiment, 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 a high compressibility region and a low compressibility region corresponding to the surface shape of the object to be hot pressed in a surface facing 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 may be, for example, a fiber sheet made of one or a combination of two or more 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 may be, for example, a plain weave, a twill weave, a satin weave, or a multi-weave of these. The fiber constituting the woven fabric may be, for example, a combination of one or two or more 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 may be selected according to the conditions of the heat press, and may be, for example, a combination of one or two or more 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 may 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] The rubber may be any known rubber, and may be selected according to the conditions of the heat press. For example, the rubber may be one or a mixture of two or more rubbers 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 of the rubbers may be selected as desired according to the purpose.

[0017] The resin may be any known resin, and may be selected according to the conditions of the heat press. Examples of the resin include one or a mixture of two or more resins 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 may be selected as desired according to the purpose.

[0018] The hot press cushioning material may have an adhesive layer interposed between the fiber layer and the elastic layer to bond the fiber layer and the elastic layer, if necessary. The adhesive material constituting the adhesive layer may be a known material having heat resistance capable of withstanding the heat from the hot press platen. The adhesive material may be rubber or resin. The rubber may be, for example, 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. The resin may be, for example, 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 adhesive such as ceramic adhesive. When a mixture is used, the combination and ratio thereof may be selected arbitrarily according to 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 of lamination of the fiber layers and the elastic layers is not particularly limited. The hot press buffer material may have an adhesive layer between the fiber layer and the elastic layer, as necessary, for bonding the fiber layer and the elastic layer. In addition, the hot press buffer material may bond the fiber layer and the elastic layer by impregnating the fiber layer with an adhesive. For example, a heat-curing silicone adhesive may be used as the adhesive.

[0020] The hot press buffer material has a high compressibility region and a low compressibility region corresponding to the surface shape of the hot press object in the surface facing the hot press object. The surface of the hot press buffer material facing the hot press object is the surface where the hot press buffer material abuts against the hot press object, or the surface where the hot press buffer material faces the hot press object via a release sheet or the like. (a) of FIG. 1 is a cross-sectional view showing a configuration in which a hot press buffer material 1 and a hot press object 2 according to the first embodiment are arranged between a pair of hot press plates of a hot press machine. (b) of FIG. 1 is a perspective view of the hot press buffer material 1 and the hot press object 2 of (a) of FIG. 1. As shown in FIG. 1, the lower hot press platen 3a and the upper hot press platen 3b of the hot press machine are arranged opposite each other, and the hot press buffer material 1 and the hot press object 2 are arranged between the lower hot press platen 3a and the upper hot 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, for example, a convex portion, facing the hot press cushioning material 1. In such an arrangement of the hot press cushioning material 1 and the hot press object 2, within the surface of the hot press cushioning material 1 facing the hot press object 2, the region facing the convex portion of the hot press object 2 is designated as a high compressibility region HA, and the other region is designated as a low compressibility region 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 hot press plates of a hot 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 of FIG. 2(a). In FIG. 2, the same members as those in FIG. 1 are given the same reference numerals and the description is omitted. 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 made into a high compression area HA, and the other area can be made into a low compression 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 around it be made into a high compression area HA, and the other area be made into a low compression area LA.

[0022] The shape of the convex portion of the heat press object is not limited to the shapes shown in Fig. 1 and Fig. 2, and can be any shape. For example, the shape of the convex portion of the heat press object can be a polygonal shape such as a cube shape and a rectangular parallelepiped shape, and a hemispherical shape. The heat press object may have two or more convex portions. As such a heat press object, an object having a concave-convex shape such as an FPC can be used. In this case, the heat press cushioning material can have a number of highly compressible regions HA corresponding to the number of convex portions of the heat press 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 end of the hot press cushioning material is preferably a low compressibility region, in order to prevent the end of the hot press cushioning material from expanding laterally when pressure is applied to the hot press cushioning material, causing a drop in pressure.

[0026] The function of the heat press cushioning material shown in FIG. 1 will be described with reference to (a) to (c) of FIG. 3. As shown in (a) of FIG. 3, the lower heat press platen 3a and the upper heat press platen 3b of the heat press machine are arranged facing each other, and the heat press object 2 and the heat press cushioning material 1 are arranged between the lower heat press platen 3a and the upper heat press platen 3b in this order from the lower heat press platen 3a side. The heat press cushioning material 1 is arranged so that its high compressibility region HA faces the convex part of the heat press object 2. In this state, when the heat press object 2 is heated to a desired temperature and pressed by the lower heat press platen 3a and the upper heat press platen 3b, the convex part of the heat press object 2 first comes into contact with the high compressibility region HA of the heat press cushioning material 1. At this time, the high compressibility region HA of the heat press cushioning material 1 has a lower compressive stress than the low compressibility region LA, so that it easily deforms to match the shape of the convex part of the heat press object 2 as shown in (b) of FIG. 3. For this reason, at the beginning of the pressurization, almost no pressure is applied from the heat press platen 3 to the convex portion of the heat press object 2. As the pressurization progresses, as shown in FIG. 3(c), the high compressibility region HA further deforms to match the convex portion of the heat press object 2, and at the same time, the low compressibility region LA abuts against the surface of the heat press object 2 other than the convex portion. That is, since the surface of the heat press cushioning material 1 abuts against the entire surface of the heat press object 2, the pressure from the heat press platen 3 can be uniformly applied to the heat press object 2 through 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 which has a simpler structure than conventional technology and is capable of applying uniform pressure to hot pressing objects of various shapes, for example 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 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 a surface facing the object to be hot pressed, a high compressibility region and a low compressibility region corresponding 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 compression region is preferably 1% or more higher than the porosity of the low compression region. In this specification, the void refers to the space generated between the fibers constituting the fiber layer, or the space formed in the pores when the elastic body constituting the elastic layer is porous. By having such a structure, the hot press buffer material can reduce the compressive stress of the high compression region by 10% or more compared to the compressive stress of the low compression region. Therefore, it has a simpler structure than the conventional technology and can transmit pressure uniformly to hot press objects of various shapes. The porosity of the high compression region and the low compression region can be calculated by the following formula (1).

[0031]

number

[0032] Here, Va is the volume of each region, Vf is the true volume of the fiber layer constituting each region, and Ve is the true volume of the elastic layer constituting 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) The true volume refers to the volume of the material itself that constitutes the layer. The true volume Vf of the fiber layer is calculated by dividing the weight of the fiber layer by the specific gravity of the fiber that constitutes the fiber layer. The specific gravity of the fiber that constitutes the fiber layer is determined by the method specified in JIS L 1013 and JIS L 1015. The true volume Ve of the elastic layer is calculated by dividing the weight of the elastic layer by the specific gravity of the elastic body that constitutes the elastic layer. The specific gravity of the elastic body that constitutes the elastic layer is determined by the method specified in JIS K 6268.

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

[0035] FIG. 4 is a cross-sectional view that illustrates 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 layered 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.

[0037] The second fiber layer 42 includes a first fiber sheet 42H constituting the high compressibility region HA and a second fiber sheet 42L constituting 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 weaving method, thickness, and thickness of the fiber threads 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 the porosity 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, the 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. The first fiber sheet 42H having the same shape as the hole is fitted into the hole to prepare 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, respectively, to form a laminate. The laminate is subjected to a thermocompression treatment and then to external shaping to obtain the hot press cushioning material shown in FIG.

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

[0040] 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, as shown in FIG.

[0041] The two elastic layers 51, 52 each include a first elastic sheet 5H constituting the high compression region HA and a second elastic sheet 5L constituting the low compression region LA. The first elastic sheet 5H is made of a porous elastic body. The second elastic sheet 5L is made of a porous or non-porous elastic body. It is preferable that the porosity of the first elastic sheet 5H is 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 compression region HA can be made 1% or more higher than the porosity of the low compression 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 constituting the high compressibility area HA and a second elastic sheet 5L constituting the low compressibility area LA.

[0042] The hot press cushioning material 1 shown in FIG. 5 can be manufactured, for example, by the following method. First, the first and second elastic sheets 5H and 5L constituting the elastic layers 51 and 52, respectively, are prepared. Here, the porosity of the first elastic sheet 5H is higher than that of the second elastic sheet 5L. A hole is formed by cutting out a portion of the second elastic sheet 5L corresponding to the high compressibility region HA. The first elastic sheet 5H having the same shape as the hole is fitted into the hole to prepare the elastic layers 51 and 52, respectively. Next, the fiber layer 4 is interposed between the elastic layers 51 and 52 to form a laminate. The laminate is subjected to a thermocompression treatment and external processing to obtain the hot press cushioning material 1 shown in FIG. 5.

[0043] FIG. 6 is a cross-sectional view that illustrates 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 and 412 corresponding to the low compressibility region LA are compressed according to the thickness of the second fiber layer 42. Alternatively, the elastic layer (at least one of the elastic layer and the adhesive layer, if the heat press buffer material 1 has an adhesive layer) is inserted into the side of the first fiber layers 411 and 412 corresponding to the low compressibility region LA facing the elastic layer according to the thickness of the second fiber layer 42. Alternatively, the portions of the first fiber layers 411 and 412 corresponding to the low compressibility region LA are compressed according to the thickness of the second fiber layer 42, and the elastic layer (at least one of the elastic layer and the adhesive layer, if the heat press buffer material 1 has an adhesive layer) is inserted into the side of the first fiber layers 411 and 412 facing the elastic layer. Therefore, the porosity of the portions of the first fiber layers 411 and 412 corresponding to the low compressibility region LA is smaller than that of the portions of the first fiber layers 411 and 412 corresponding to the high compressibility region HA. The porosity of the second fiber layer 42 is smaller than that of the portions of the first fiber layers 411, 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 constitute 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 constituting the second fiber layer 42 is prepared. A portion corresponding to the high compressibility region HA of the fiber sheet is cut out to form a through hole, and the second fiber layer 42 is prepared. 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 subjected to a thermocompression treatment to compress the laminate. By adjusting the shape and depth of the through hole, the physical properties of the fiber layer and the elastic layer 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 thickness direction of the through hole are deformed so as to contact 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 corresponding to the low compression region LA of the first fiber layer 411 and 412 is compressed according to the thickness of the second fiber layer 42. Or, the elastic layer (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 facing the elastic layer of the portion. Or, both the compression of the first fiber layer and the penetration of the elastic layer occur. In this way, the thickness of the portion corresponding to the low compression region LA of the first fiber layer 411 and 412 is reduced, the porosity is reduced, and the porosity of the low compression region LA becomes smaller than that of the high compression region HA. In this way, the high compression region HA and the low compression region LA are formed in the laminate. The laminate in which the high compressibility areas HA and the low compressibility areas LA are formed is subjected to external shaping to obtain the hot press cushioning material 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 a high compressibility region and a low compressibility region corresponding to the surface shape of the hot press object in a surface facing 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 a through hole, a blind hole, and a depression in the high compressibility region. The through hole and the blind hole are formed in at least one layer other than the top layer and the bottom layer of the layer structure. The depression is formed in at least one of the top layer and the bottom layer of the layer structure.

[0050] The hot press cushioning material has a three or more 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 such that the holes penetrate from top to bottom in the thickness direction. An example of a layer in which the 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 such that the holes penetrate from top to bottom in the thickness direction.

[0054] The non-through holes are formed in at least one of the upper and lower sides in the thickness direction of the layer in which the non-through holes are formed. An example of a layer in which non-through 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 non-through holes 62 are formed in the upper side in the thickness direction of the layer 72 in which the non-through holes 62 are formed. In FIG. 7(b) and FIG. 8(b), the layer 71 having the through holes and the layer 72 having the non-through holes are shown as elastic layers as an example, but are not limited thereto and may be fiber layers.

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

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

[0057] The volume of the through holes, non-through holes and depressions is preferably 1% or more of the volume of the highly compressible region. 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 cushioning material for hot pressing is t max Then, the volume of the highly compressible region is Va H is calculated by the following formula (3): Fig. 9 shows, as an example, a highly compressible region in which through holes or non-through holes are formed. In Fig. 9, reference numeral 60 denotes a through hole or a non-through hole.

[0058] Va H =s H ×t max (3) When at least one of the fiber layer and the elastic layer constituting the high compression region and the low compression region of the hot press cushioning material has voids, the same effect can be obtained by making the ratio of the total volume of the voids, through holes, non-through holes and depressions in the high compression region to the volume of the high compression region 1% or more higher than the ratio of the volume of the voids in the low compression region to the volume of the low compression region. The volume ratio of the voids, through holes, non-through holes and depressions is 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 porosity formula (1).

[0060] By having such a structure, the cushioning material for hot press 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 the conventional technology and can transmit pressure uniformly to hot press objects of various shapes.

[0061] FIG. 10 is a cross-sectional view that illustrates an example of the hot-press cushioning material 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 layer and the bottom layer of the layered structure. The through holes 61 are formed in the second fiber layer 42 so as to penetrate 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 showing another example of the hot-press cushioning material 1 according to the third embodiment. The description of the same configuration as that of the example of the hot-press cushioning material 1 according to the third embodiment will be omitted by citing the above description.

[0065] The hot press cushioning material 1 has a through hole 61 and a depression 63 in the high compressibility region HA. The through hole 61 is formed in the second fiber layer 42, which is one of the layers other than the top layer and the bottom layer of the layered structure. The depression 63 is formed in the first fiber layer 412, which is the top layer of the layered structure. The depression 63 is formed by bending the first fiber layer 412 and the elastic layer 52, which are located above the through hole 61, toward the through hole 61, which correspond to the high compressibility region. The total volume of the through hole 61 and the depression 63 relative to the volume of the high compressibility region HA is preferably 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 constituting the second fiber layer 42 is prepared. A portion corresponding to the high compressibility region HA of the fiber sheet is cut out to form a through hole 61, and the second fiber layer 42 is prepared. 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, respectively, to form a laminate. As a result, the through hole 61 is formed in the second fiber layer 42. The laminate is subjected to a thermocompression treatment to compress the laminate. The laminate is subjected to an external shape processing to obtain 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 layer and the elastic layer constituting the hot-press cushioning material, and the thermocompression treatment conditions, the first fiber layer 412 and the portion of the elastic layer 52 that exists above the through hole 61 and corresponds to the highly compressible region are deflected toward the through hole 61. As a result, a depression 63 is formed in the first fiber layer 412, and the hot-press cushioning material 1 shown in FIG. 11 is obtained.

[0067] <Fourth embodiment> The cushioning material for hot press according to the fourth 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 a surface facing the object to be hot pressed, a high compressibility region and a low compressibility region corresponding 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. In at least one layer of the elastic layer, the portion corresponding to the high compressibility region has a hardness measured by a type A durometer based on JIS K6253 that is 15 degrees or more lower than the portion corresponding to the low compressibility region.

[0068] In at least one of the elastic layers, a 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 a portion corresponding to the low compressibility region.

[0069] By having such a structure, the cushioning material for hot press 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 the conventional technology and can transmit pressure uniformly to hot press objects of various shapes.

[0070] FIG. 12 is a cross-sectional view that illustrates an example of the hot-press cushioning material 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, 52 are laminated with a fiber layer 4 interposed between them.

[0072] Each of the two elastic layers 51, 52 includes 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 measured with a type A durometer based on JIS K6253 is preferably 15 degrees or more lower than that of the second elastic sheet 5L. Only one of the elastic layers on the side facing the object to be heat 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, the first and second elastic sheets 5H and 5L constituting the elastic layers 51 and 52, respectively, are prepared. Here, the hardness of the first elastic sheet 5H measured with a type A durometer based on JIS K6253 is 15 degrees or more lower than that of the second elastic sheet 5L. The second elastic sheet 5L is cut out at a portion corresponding to the high compressibility region HA to form a hole. The first elastic sheet 5H having the same shape as the hole is fitted into the hole to prepare the elastic layers 51 and 52, respectively. 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 subjected to a thermocompression treatment and external processing 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 a surface facing the object to be hot pressed, a high compressibility region and a low compressibility region corresponding 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.

[0075] The hot-press cushioning materials 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 hot-press objects of various shapes.

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

[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 (weight: 400 g / m2 , thickness: 0.70 mm) was prepared. A first aramid woven fabric (basis weight: 82 g / m) for producing a 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 portion of the second aramid woven fabric was cut out to form a hole having a width of 300 mm and a depth of 300 mm. The first aramid woven fabric having 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 Omi 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 obtained rubber compound was molded into a sheet with a thickness of 0.20 mm to prepare a rubber layer.

[0080] The first fiber layer, the second fiber layer, and the rubber layer were laminated from the bottom in the order of 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 the laminate. The rubber layer was vulcanized by the press to form an elastic layer. In this manner, a hot press cushioning material was produced. 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 agent 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, the foaming agent, and the colored silicone rubber were dispersed in the raw rubber in 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 obtained rubber compound was molded into a sheet with a thickness of 0.53 mm to prepare a first unfoamed 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 the colored silicone rubber were dispersed in the raw rubber in 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 obtained rubber compound was molded into a sheet with a thickness of 0.95 mm to prepare a second unfoamed 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: 61g / m 2A laminate (0.14 mm thick, 0.03 mm thick) was prepared. The aramid woven fabric was impregnated with TSE322 (manufactured by Momentive Performance Materials Japan LLC) by dipping and nipping the aramid woven fabric. The rubber layer and the fiber layer were laminated from the bottom in the order of 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 laminate. The rubber layer was vulcanized and foamed by the press to form an elastic layer. When forming by pressing, a spacer with a thickness of 2.00 mm was placed around the laminate placed in the press machine before pressing. In this manner, a cushioning material for hot pressing was produced. The width of the cushioning material for hot pressing was 500 mm, the depth was 500 mm, and the thickness was 2.0 mm.

[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 on the elastic layer functioned as the high compression region HA, and the portion having the second rubber sheet on the elastic layer functioned as the low compression region LA.

[0087] Example 3 The first fiber layer is aramid woven fabric (weight: 400 g / m 2 , thickness: 0.70 mm) was prepared. Aramid woven fabric (weight: 170 g / m) for producing the second fiber layer 2 A second fiber layer was prepared by cutting out the center of the sheet (thickness: 0.35 mm) 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] The first fiber layer, the second fiber layer, and the rubber layer were laminated from the bottom in the order of the 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 bond the laminate. The rubber layer was vulcanized by the press to form an elastic layer. The first fiber layer and the elastic layer present on the through hole provided in the second fiber layer were also bent toward the through hole by the press to form a recess in the central 300 mm x 300 mm part of the upper surface in the thickness direction of the hot press cushioning material. In this manner, the hot press cushioning material was produced. The width of the hot press cushioning material was 500 mm, the depth was 500 mm, and the thickness was 1.5 mm.

[0090] In the hot-press cushioning material of Example 3, the central portion (width 300 mm×depth 300 mm×thickness 1.5 mm) having the through-hole and the recess functioned as the high compressibility area HA, and the other portion functioned as the low compressibility area 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 Omi Chemical Industry Co., Ltd.). The filler, vulcanization aid, and vulcanization accelerator were dispersed in the raw rubber so that the weight ratio (raw rubber:filler:vulcanization aid:vulcanization accelerator) was 100:5:3:6, and a rubber compound was prepared. The obtained rubber compound was molded into a sheet having a thickness of 0.60 mm to prepare 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: 82g / m 2 A laminate (0.19 mm thick, 0.02 in diameter) was prepared, and a rubber layer and a fiber layer were laminated from the bottom in the order of rubber layer / fiber layer / rubber layer to obtain a laminate. The laminate was pressed and molded for 30 minutes at a temperature of 170°C and a pressure of 0.5 MPa. The rubber layer was vulcanized by the press to form an elastic layer. In this manner, a hot press cushioning material was produced. The hot press cushioning material had a width of 500 mm, a depth of 500 mm, and a thickness of 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 on the elastic layer functioned as the high compression region HA, and the portion having the second rubber sheet on the elastic layer functioned as the low compression 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 into an elastomer was measured using a hardness measurement sheet. The hardness measurement sheet was prepared by pressing the first and second rubber sheets prepared in the same manner as in Example 2 at a temperature of 170°C and a pressure of 0.5MPa for 30 minutes. The type A durometer hardness of the first rubber sheet when vulcanized into an elastomer was 65, and the type A durometer hardness of the second rubber sheet when vulcanized into an elastomer was 80. The type A durometer hardness was measured based on JIS K6253.

[0097] Comparative Example 1 The second fiber layer is made of aramid woven fabric (weight: 170 g / m 2 A cushioning material for hot press was produced in the same manner as in Example 1, except that a 0.35 mm thick sheet (1.0 mm thick, thickness: 0.35 mm) was used.

[0098] Comparative Example 2 The raw rubber X-30-4600-U (Shin-Etsu Chemical Co., Ltd.), the vulcanizing agent C-8 (Shin-Etsu Chemical Co., Ltd.), 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 the colored silicone rubber were dispersed in the raw rubber in 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 obtained rubber compound was molded into a sheet with a thickness of 0.95 mm to prepare a 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 Omi 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 obtained 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-mentioned 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 into 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 into 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 area HA and the low compressibility area 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 area HA and the low compressibility area LA was calculated using the following formula (4). The results are shown in Tables 1 and 2.

[0105] [Porosity difference] = [Porosity of high compressibility region HA] - [Porosity 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. In addition, 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 each of the hot-press cushioning materials 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 at the point where the compressive stress reached 2 MPa (hereinafter, displacement δ LA Next, the terminal of the universal testing machine was pressed into the highly compressible region HA of the hot press cushioning 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 high compressibility region HA was measured at the point when the displacement δ was equal to the value of the high compressibility region HA. For the hot press cushioning material of Example 3, the compressive stress of the high compressibility region HA was measured on the surface where the depression was formed. HA and displacement δ LAwas measured using the maximum thickness of each hot press cushioning material as the reference (i.e., displacement was 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 compressive area HA and the low compressive area LA to the compressive stress of the low compressive area LA was calculated using the following formula (5). The compressive stress of the low compressive area 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 by the heat press machine was evaluated by the following test using the heat press cushioning materials of Examples 1 to 4 and Comparative Examples 1 to 3. As shown in FIG. 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 convex portion (width 300 mm x depth 300 mm) in the center (hereinafter, heat press object 2, material: PI (polyimide)), and pressure-sensitive paper 9 (high-temperature press scale LLW, manufactured by Fujifilm) were laminated 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. At this time, the highly compressible region HA of the heat press cushioning material 12 and the convex portion of the heat press object 2 were placed and laminated so as to face each other. Furthermore, for the test of Example 3, the heat press cushioning materials 11 and 12 were arranged so that the side on which the depression was formed faced the heat press object 2. The height of the convex part of the heat press object 2 was 0.10 mm for the evaluation of Examples 1 and 3 and Comparative Example 1, and 0.025 mm for the evaluation of Example 4 and Comparative Example 3. For the evaluation of Example 2 and Comparative Example 2, a sheet-like film (width 300 mm x depth 300 mm, material: PI (polyimide)) having a thickness of 0.125 mm was laminated on the convex part of the heat press object 2, and the height of the entire convex part was set to 0.75 mm. Pressing was performed at a temperature of 180°C and a pressure of 2 MPa using the heat press machines 3a and 3b. The density of the discoloration on the surface of the pressure-sensitive paper 9 was measured using a spectrodensitometer (spectrodensitometer Spectrodensitometer, manufactured by TECHKON) to evaluate the uniformity of the pressure. If the difference between the maximum and minimum values ​​of the density of the discoloration on the surface of the pressure-sensitive paper 9 was within 0.1, it was judged as good, and otherwise it 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 hot-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 hot-press object, corresponding to the surface shape of the hot-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, are all capable of applying pressure from the hot-press platen uniformly to the hot-press object.

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

[0116] As is clear from Tables 1 and 2, in the hot 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, the compressive stress of the high compressibility region HA is 10% or more lower than the compressive stress of 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, blind holes and depressions in the high compressibility region, the through holes and blind 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 has 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.

[0118] Furthermore, as is clear from Table 4, 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 based on JIS K6253 that is 15 degrees or more lower than the portion corresponding to the low compressibility region in the hot press cushioning material of Example 4, and 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] Reference Signs List: 1...cushioning material for heat press, 2...object to be heat pressed, 3...heat press platen, 4...fiber layer, 5...elastic layer, 61...through hole, 62...non-through hole, 63...depression, 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 area, LA...low compressibility area.

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 a hot-press object is provided with a high compressibility region and a low compressibility region corresponding to the surface shape of the hot-press object, 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. The cushioning material for hot press 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. 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 is provided with 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, 2. 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. The hot press cushioning material according to claim 1, wherein in at least one of the elastic layers, a portion corresponding to the high compressibility region has a hardness measured with a type A durometer based on JIS K6253 that is 15 degrees or more lower than a portion corresponding to the low compressibility region.

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