Patent Grant
10272642
The present application is a national phase application of PCT Application No. PCT/JP2015/068652, filed Jun. 29, 2015, which claims priority to Japanese Patent Application No. 2014-134795, filed on Jun. 30, 2014, the entire contents of which are herein incorporated by reference.
The present invention relates to cushioning materials for hot press and manufacturing methods thereof. More particularly, the present invention relates to cushioning materials for hot press which are used when an intended product is press formed or thermocompression bonded in a process of manufacturing a precision equipment component (hereinafter referred to as “laminate” in the present invention) such as a printed circuit board like a copper-clad laminate, a flexible printed circuit board, or a multilayer board, an IC card, a liquid crystal display panel, or a ceramic laminate, and manufacturing methods thereof.
When manufacturing a laminate such as a printed circuit board, the following method is used in a press-forming or thermocompression bonding process. As shown in
Conventionally, a paper cushioning material such as kraft paper, a felt cushioning material, etc. is used as such a hot press cushioning material 111. Paper cushioning materials are inexpensive and have cushioning properties. However, the paper cushioning materials cannot be restored after pressing and therefore cannot be repeatedly used for a plurality of presses. Moreover, if the paper cushioning materials are used at high temperatures (e.g., 200° C. or higher), they get burnt and stuck on the heating platens 113, producing paper dust.
Felt cushioning materials are flexible and therefore have cushioning properties. However, the felt cushioning materials, due to their poor temporal stability, cannot uniformly transmit the heat and the pressure from the heating platens 113 to the laminate material 112 across the entire pressing surface after repeated use. Repeated use of the felt cushioning materials therefore produces defective pressed products and also causes fibers to coming off from the surfaces of the felt cushioning materials.
Japanese Patent Nos. 4746523 (Patent Literature 1), 5341733 (Patent Literature 2), 4183558 (Patent Literature 3), etc. propose a hot press cushioning material that can be repeatedly used for high temperature press.
Patent Literature 1 discloses a hot press cushioning material that includes a fiber-rubber composite material layer made of a woven fabric and rubber with which the woven fabric has been impregnated. Bulky yarn made of glass fiber is used as at least one of warp and weft of the woven fabric, and the fiber-rubber composite material layer has voids therein. Patent Literature 2 discloses a hot press cushioning material that includes a surface layer material placed in its surface layer. The surface layer material is formed by a woven fabric layer comprised of bulky yarn, a resin layer covering one surface of the woven fabric layer, and a rubber layer covering the other surface of the woven fabric layer. The woven fabric layer has a woven fabric-resin composite layer and a woven fabric-rubber composite layer and has voids therein. Patent Literature 3 discloses a hot press cushioning material that includes a base material and a releasable coating film formed on the base material and made of a resin composition. The releasable coating film contains a base material comprised of a predetermined resin, and organic powder and inorganic powder which are mixed with the base material.
Patent Literature 1: Japanese Patent No. 4746523
Patent Literature 2: Japanese Patent No. 5341733
Patent Literature 3: Japanese Patent No. 4183558
Recent printed circuit boards are very thin (e.g., 50 μm or less) and are produced by using a resin having high heat resistance. If a pressure is even slightly unevenly applied in hot press when producing such a printed circuit board, the resultant product has defects such as air bubbles, an unsatisfactory thickness, or an unintended thin portion. The hot press cushioning materials described in Patent Literatures 1 to 3 are not flexible at their surfaces and therefore spot deformation is less likely to occur in these hot press cushioning materials. Accordingly, these hot press cushioning materials do not sufficiently conform to fine unevenness. Accordingly, if the hot press cushioning materials described in Patent Literatures 1 to 3 are used in hot press to produce a laminate such as a recent printed circuit board, these cushioning materials may not be able to absorb unevenness of the heating platens 113 etc. such as small warps or flaws.
In view of the above problem, it is an object of the present invention to provide a hot press cushioning material that has improved conformability to fine unevenness and that can be used repeatedly.
A hot press cushioning material according to the present invention includes as a base material: a woven fabric layer using bulky yarn as at least one of warp and weft; and a nonwoven fabric layer placed on one surface side of the woven fabric layer, a part of the nonwoven fabric layer being embedded in the woven fabric layer. A nonwoven fabric-resin composite layer is formed in an opposite surface of the nonwoven fabric layer from the woven fabric layer by impregnation with resin, and a woven fabric-rubber composite layer is formed in the other surface of the woven fabric layer by impregnation with rubber. The nonwoven fabric-resin composite layer and the woven fabric-rubber composite layer have voids therein.
A method for manufacturing a hot press cushioning material according to the present invention includes the steps of preparing a woven fabric layer using bulky yarn as at least one of warp and weft; placing a nonwoven fabric layer on one surface side of the woven fabric layer and embedding a part of the nonwoven fabric layer into the woven fabric layer; impregnating the stack of the woven fabric layer and the nonwoven fabric layer with resin from an opposite surface of the nonwoven fabric layer from the woven fabric layer to form a nonwoven fabric-resin composite layer; and impregnating the stack with rubber from the other surface of the woven fabric layer to form a woven fabric-rubber composite layer.
According to the hot press cushioning material and the method for manufacturing the same of the present invention, the base material of the cushioning material is the stack of the woven fabric layer using the bulky yarn and the nonwoven fabric layer, with a part of the nonwoven fabric layer being embedded in the woven fabric layer. The woven fabric layer and the nonwoven fabric layer are joined together by tangling of fibers, namely without using an adhesive, and the fibers can be prevented from coming off from the nonwoven fabric layer. Since the nonwoven fabric layer is stacked on the woven fabric layer using the bulky yarn, the hot press cushioning material is flexible at its surface and can absorb fine unevenness. Moreover, shape stability can be maintained by the woven fabric using the bulky yarn.
The nonwoven fabric-resin composite layer can prevent fluffing on the surface by the resin with which the nonwoven fabric has been impregnated and can provide release properties as a surface layer of the hot press cushioning material. The resin does not completely fill the voids in the nonwoven fabric and the nonwoven fabric-resin composite layer has a certain level of void properties. The hot press cushioning material is therefore flexible at its surface and can absorb fine unevenness.
When the woven fabric is impregnated with the rubber, the rubber enters the voids of the bulky yarn and the voids in the weave as appropriate. The rubber does not completely fill the voids and the woven fabric-rubber composite layer has a certain level of void properties. This provides satisfactory cushioning properties. Since the rubber protects the fibers and joins the contact points between the fibers, breakage of the fibers and what is called loss of resilience are prevented, and the void properties can be maintained and thus satisfactory cushioning properties can be maintained even after repeated use for a plurality of hot presses. Accordingly, the hot press cushioning material of the present invention has improved conformability to fine unevenness and can be used repeatedly.
In the hot press cushioning material of the present invention, a part of the nonwoven fabric layer may be impregnated with the rubber of the woven fabric-rubber composite layer to form a nonwoven fabric-rubber composite layer. In this case, the nonwoven fabric-rubber composite layer has voids therein.
As described above, the hot press cushioning material in which a part of the nonwoven fabric layer has also been impregnated with the rubber of the woven fabric-rubber composite layer also has conformability to fine unevenness and can be used repeatedly. In addition, in the case where the nonwoven fabric layer is also impregnated with the rubber of the rubber layer, the rubber joins the contact points between the fibers of the nonwoven fabric and therefore can prevent loss of resilience of the nonwoven fabric layer. Since the rubber does not completely fill the voids in the nonwoven fabric layer and the nonwoven fabric-rubber composite layer has the voids, satisfactory cushioning properties can be maintained.
In the hot press cushioning material of the present invention, it is preferable that the bulky yarn include at least one kind of fiber selected from glass fiber, meta-aromatic polyamide fiber, para-aromatic polyamide fiber, and polypara phenylene benzobisoxazole fiber. Two or more of these kinds of fiber may be combined or the fiber selected from these kinds may be combined with other fiber. Among these, glass fiber is particularly preferred. Glass fiber has heat resistance and the dimensions of glass fiber changes only slightly by heat. Accordingly, in the case where the bulky yarn is glass fiber, shape stability of the hot press cushioning material can be more satisfactorily maintained even after repeated use.
In the hot press cushioning material of the present invention, it is preferable that the rubber with which the woven fabric layer is impregnated include at least one kind of rubber selected from fluororubber, EPM, EPDM, hydrogenated nitrile rubber, silicone rubber, acrylic rubber, and butyl rubber. Two or more of these kinds of rubber may be mixed or the rubber selected from these kinds may be mixed with other rubber. Among these, fluororubber is particularly preferred. Fluororubber has excellent physical properties such as heat resistance and strength. Accordingly, in the case where the rubber of the rubber layer is fluororubber, properties of the hot press cushioning material can be improved.
In the hot press cushioning material of the present invention, it is preferable that nonwoven fabric of the nonwoven fabric layer include at least one kind of fiber selected from meta-aromatic polyamide fiber, para-aromatic polyamide fiber, and polypara phenylene benzobisoxazole fiber. Two or more of these kinds of fiber may be combined or the fiber selected from these kinds may be combined with other fiber. Among these, meta- or para-aromatic polyamide fiber is particularly preferred. Aromatic polyamide fiber has excellent physical properties such as flexibility and heat resistance. Accordingly, in the case where the nonwoven fabric of the nonwoven fabric layer is aromatic polyamide fiber, properties and conformability to fine unevenness of the hot press cushioning material can be improved.
In the hot press cushioning material of the present invention, it is preferable that the resin with which the nonwoven fabric layer is impregnated include at least one kind of resin selected from polyimide resin, fluororesin, phenol resin, melamine resin, epoxy resin, unsaturated polyester resin, silicone resin, thermosetting acrylic resin, furan resin, urea resin, diallyl phthalate resin, and polyurethane resin. Among these, polyimide resin or fluororesin is particularly preferred. Polyimide resin and fluororesin have excellent physical properties such as heat resistance and release properties. Accordingly, properties of the hot press cushioning material can be improved.
According to the hot press cushioning material and the method for manufacturing the same of the present invention, a hot press cushioning material can be provided which has improved conformability to fine unevenness and which can be used repeatedly.
Embodiments of the present invention will be described below with reference to the accompanying drawings. In the figures described below, the same or corresponding portions are denoted with the same reference characters, and description thereof will not be repeated.
A hot press cushioning material 10 according to an embodiment of the present invention will be described with reference to
As shown in
Bulky yarn 12 is used as at least one of warp and weft of the woven fabric layer 11. That is, bulky yarn may be used as either one or both of the warp and weft of woven fabric. In the case where bulky yarn is used as one of the warp and weft, normal single yarn or double twisted yarn can be used as the other. In the present embodiment, as shown in
The layer structure of the woven fabric may be either a single weave structure or a multiple weave structure. Weaving methods include plain weave, twill weave, and other weaves. However, the present invention is not limited to a specific weaving method. The basis weight and the void properties of the woven fabric can be adjusted by selecting a yarn count, a weave density, a weaving method, etc. as appropriate. It is preferable that the basis weight of the woven fabric of the woven fabric layer 11 be 500 g/m2 or more and 2,000 g/m2 or less. A hot press cushioning material having high dimensional stability, high durability, and high in-plane uniformity can be produced by using woven fabric of such basis weight.
The bulky yarn 12 is yarn occupying a large area, in which short fibers forming bulky yarn are not parallel to each other but are tangled and are arranged in a disordered state. In other words, the bulky yarn is bulky like wool yarn. Therefore, unlike a normal woven fabric, the woven fabric using the bulky yarn has many voids therein. Although not particularly limited, the bulky yarn may be made of glass fiber, meta-aromatic polyamide fiber, para-aromatic polyamide fiber, polypara phenylene benzobisoxazole (PBO) fiber, etc., and is preferably made of glass fiber.
For example, the types of the bulky yarn 12 include bulked yarn, staple yarn, sliver yarn, etc. The bulked yarn is yarn bulked by air jet processing etc. The staple yarn is yarn produced by spinning cotton-like glass short fibers into a thread. The sliver yarn is yarn produced by twisting untwisted bulky short fibers (slivers). The bulky yarn 12 is preferably bulked yarn. The bulked yarn is processed yarn made bulky like wool yarn by opening fibers of single yarn or bulking double twisted yarn by air jet processing. The woven fabric using the bulked yarn therefore has a high void ratio and can be appropriately impregnated with rubber and resin. For example, A305, A330, A400, A415, A450, A500, T330, T540, T790, T860, and T900 made by Unitika Ltd., KS4010, KS4155, and KS4325 made by Nitto Boseki Co., Ltd., etc. can be used as the woven fabric using bulked yarn of glass fiber.
The nonwoven fabric layer 14 is placed on one surface side of the woven fabric layer 11 (the upper side of the woven fabric layer 11 in
The nonwoven fabric layer 14 is a thin film-like sheet made of only fiber and is also called a web. The nonwoven fabric layer 14 is comprised of organic fiber. Although not particularly limited, the organic fiber may be, e.g., meta-aromatic polyamide fiber, para-aromatic polyamide fiber, polypara phenylene benzobisoxazole fiber, etc., and meta- or para-aromatic polyamide fiber is particularly preferred.
The basis weight of the nonwoven fabric of the nonwoven fabric layer 14 is preferably 10 g/m2 or more and 300 g/m2 or less, and more preferably 30 g/m2 or more and 100 g/m2 or less. Improved conformability to fine unevenness is achieved in the case where the basis weight is 10 g/m2 or more, and further improved conformability to fine unevenness is achieved in the case where the basis weight is 30 g/m2 or more. The risk of loss of resilience of the nonwoven fabric layer 14 after repeated use for hot press can be reduced in the case where the basis weight is 300 g/m2 or less, and this risk can further be reduced in the case where the basis weight is 100 g/m2 or less. In the hot press cushioning material of the present invention, the basis weight of the nonwoven fabric layer 14 is made sufficiently lighter than that of the woven fabric 11. Conformability to fine unevenness can therefore be improved by the nonwoven fabric layer 14 without affecting dimensional stability, durability, and in-plane uniformity.
The hot press cushioning material 10 has the nonwoven fabric-resin composite layer 18 at least in the opposite surface (the upper surface in FIGS. 1 to 7) of the nonwoven fabric layer 14 from the woven fabric layer 11. The fibers of the nonwoven fabric layer 14 are therefore not exposed and fluffing is restrained.
Although not particularly limited, resin 15 with which the nonwoven fabric is impregnated to form the nonwoven fabric-resin composite layer 18 may be, e.g., polyimide resin, fluororesin, phenol resin, melamine resin, epoxy resin, unsaturated polyester resin, silicone resin, thermosetting acrylic resin, furan resin, urea resin, diallyl phthalate resin, polyurethane resin, etc., and polyimide resin or fluororesin is particularly preferred.
The hot press cushioning material 10 has the woven fabric-rubber composite layer 19 on the other surface side (the lower side in
Although not particularly limited, rubber 16 with which the woven fabric is impregnated to form the woven fabric-rubber composite layer 19 may be, e.g., fluororubber, EPM, EPDM, hydrogenated nitrile rubber, silicone rubber, acrylic rubber, butyl rubber, etc., and fluororubber is particularly preferred.
As shown in
The nonwoven fabric-resin composite layer 18 and the woven fabric-rubber composite layer 19 have voids 17 therein. The voids 17 serve as a cushion. The nonwoven fabric-resin composite layer 18 and the woven fabric-rubber composite layer 19 preferably have a void-to-volume ratio of 20% or more and 70% or less.
Specifically, in the structure shown in
In the structure shown in
In the structure shown in
In the structure shown in
In the structure shown in
In the structures shown in
A method for manufacturing the hot press cushioning material 10 of the embodiment will be described below with reference to
First, the woven fabric layer 11 using the bulky yarn 12 as at least one of warp and weft is prepared as shown in
Next, as shown in
Then, as shown in
In this step, the impregnation with the resin 15 is performed from the nonwoven fabric layer 14 side so that the resin 15 does not penetrate to the other surface side of the woven fabric layer 11 (the opposite side of the woven fabric layer 11 from the nonwoven fabric layer 14). That is, the impregnation with the resin 15 is performed so that the bulky yarn 12 of the woven fabric layer 11 is exposed from the opposite surface of the woven fabric layer 11 from the nonwoven fabric layer 14. The nonwoven fabric-resin composite layer 18 shown in
In this step, the nonwoven fabric layer 14 and a part of the woven fabric layer 11 may be impregnated with the resin 15. Namely, the impregnation with the resin 15 may be performed so that the side of the woven fabric layer 11 which faces the nonwoven fabric layer 14 is impregnated with the resin 15 and the bulky yarn 12 of the woven fabric layer 11 is exposed from the opposite surface of the woven fabric layer 11 from the nonwoven fabric layer 14 is exposed. As shown in
In this step, the entire nonwoven fabric layer 14 may be impregnated with the resin 15 as shown in
The depth to which the impregnation with the resin 15 is performed can be adjusted as desired by changing the viscosity of the resin varnish as appropriate.
Subsequently, the stack of the woven fabric layer 11 and the nonwoven fabric layer 14 is impregnated with the rubber 16 from the woven fabric layer 11 side (the other surface side of the woven fabric layer 11). This step includes the steps of causing an unvulcanized rubber solution to penetrate the stack of the woven fabric layer 11 and the nonwoven fabric layer 14 from the other surface side of the woven fabric layer 11, drying the unvulcanized rubber solution having penetrated the woven fabric layer 11, and vulcanizing the dried unvulcanized rubber. The woven fabric-rubber composite layer 19 shown in
In this step, the woven fabric layer 11 and a part of the nonwoven fabric layer 14 may be impregnated with the rubber 16. In this case, as shown in
As in the case of the impregnation with the rubber 15, the depth to which the impregnation with the rubber 16 is performed can also be adjusted as desired by changing the viscosity of the unvulcanized rubber solution as appropriate.
In
The hot press cushioning material 10 shown in
Specifically, a hot press cushioning material 30 shown in
A hot press cushioning material 33 shown in
A hot press cushioning material 34 shown in
Other cushioning materials 32 shown in
In the case of manufacturing the hot press cushioning materials of
The hot press cushioning materials 30, 33 to 35 of
As shown in
As in conventional examples, the hot press cushioning materials 10, 30, 33 to 35 of the embodiments shown in
The present invention will be described in more detail with respect to examples. However, the present invention is not limited to the following examples.
Glass woven fabric “T860” using bulky yarn (made by Unitika Ltd.) was prepared as a woven fabric layer. The weft of the woven fabric was bulky yarn formed by bulking 305-tex double twisted yarn of 3,200 E-glass fibers (fiber diameter: 6 μm), and the warp thereof was 135-tex unbulked double twisted yarn of 1,600 E-glass fibers (fiber diameter: 6 μm). The woven fabric was formed by weaving the warp and weft in double weave. The woven fabric had a basis weight of 850 g/m2.
A web of “Technora” (made by TEIJIN LIMITED) using para-aromatic polyamide fiber was prepared as a nonwoven fabric layer. The basis weight of the web was 70 g/m2. The web was placed on one surface side of the woven fabric layer and a part of fibers forming the web was embedded into the woven fabric layer by needle punching. The woven fabric layer and the nonwoven fabric layer were thus stacked to form a base material with an integrated structure of the woven fabric layer and the nonwoven fabric layer.
Polyimide resin in the form of varnish was then applied to the base material from the surface side of the nonwoven fabric layer (the opposite side of the nonwoven fabric layer from the woven fabric layer), and the resultant base material was dried and baked. The nonwoven fabric layer was thus impregnated with the polyimide resin to form a nonwoven fabric-resin composite layer.
Subsequently, an unvulcanized fluororubber solution was applied to the base material from the surface side of the woven fabric layer (the other surface side of the woven fabric layer (the opposite side of the woven fabric layer from the nonwoven fabric layer), and the resultant base material was dried. The woven fabric layer was thus impregnated with the unvulcanized fluororubber. Thereafter, the base material was baked at 230° C. for five hours to vulcanize the fluororubber. A woven fabric-rubber composite layer was formed in this manner.
By performing the above process, the hot press cushioning material 10 including the woven fabric-rubber composite layer 19 having the voids 17 and having a part of the fibers of the nonwoven fabric embedded therein, the nonwoven fabric layer 14 formed on the woven fabric-rubber composite layer 19, and the nonwoven fabric-resin composite layer 18 formed on the nonwoven fabric layer 14 and having the voids as shown in
Two of the hot press cushioning material bodies were produced. As shown in
A hot press cushioning material of Example 2 was basically manufactured in a manner similar to that of Example 1, but was different from Example 1 in that fluororesin in the form of varnish was used instead of the polyimide resin to impregnate the nonwoven fabric layer. The nonwoven fabric layer was impregnated with the fluororesin and the woven fabric layer was impregnated with the fluororubber. A hot press cushioning material body was thus produced which included the woven fabric-rubber composite layer 19 having the voids 17 and having a part of the fibers of the nonwoven fabric embedded therein and the nonwoven fabric-resin composite layer 18 formed on the woven fabric-rubber composite layer 19 and having the voids 17 as shown in
Two of the hot press cushioning material bodies were produced, and the hot press cushioning material of Example 2 having the structure shown in
A hot press cushioning material of Comparative Example 1 included two cushioning material bodies 41, two surface layer materials 42 placed on the outside of the cushioning material bodies 41, and an adhesive material layer 31 bonding the two cushioning material bodies, as shown in
Each of the cushioning material bodies 41 was produced as follows. First, glass woven fabric “T860” using bulky yarn (made by Unitika Ltd.) was prepared and impregnated with an unvulcanized fluororubber solution. The resultant glass woven fabric was sufficiently dried to remove the solvent. The dried glass woven fabric was baked at 230° C. for five hours. The cushioning material body 41 was thus produced. This cushioning material body 41 was a woven fabric-rubber composite having voids. See Japanese Patent No. 4746523 for the details of the configuration of the cushioning material body of Comparative Example 1 and the manufacturing method thereof.
Each of the surface layer materials 42 was produced as follows. Glass woven fabric “A515” using bulky yarn (made by Unitika Ltd.) was prepared as woven fabric. This woven fabric had a basis weight of 515 g/m2. Fluororesin in the form of varnish was applied to one surface side of the prepared glass woven fabric, and the resultant glass woven fabric was dried and baked. After the baking, unvulcanized fluororubber was applied to the back surface of the glass woven fabric, and the resultant glass woven fabric was dried. This surface layer material 42 included a woven fabric-rubber composite layer and a woven fabric-resin composite layer formed on the woven fabric-rubber composite layer. See Japanese Patent No. 5341733 for the details of the configuration of the surface layer material 42 of Comparative Example 1 and the manufacturing method thereof.
Subsequently, the two cushioning material bodies 41 were placed with the same adhesive layer 31 as that used in Example 1 interposed therebetween, and the two surface layer materials 42 were placed such that their surfaces impregnated with the unvulcanized fluororubber faced the two cushioning material bodies 41. The adhesive layer 31 and the unvulcanized fluororubber of the surface layer materials 42 were vulcanized to bond the surface layer materials 42, the cushioning material bodies 41, and the adhesive layer 31 together.
A hot press cushioning material 40 of Comparative Example 1 shown in
A hot press cushioning material 40 of Comparative Example 2 had the structure shown in
The mixture thus produced was applied to one surface of the base material by knife coating, and the resultant base material was dried and baked. Unvulcanized fluororubber was applied to the other surface side of the base material, and the resultant base material was dried. The surface layer material 42 was thus produced. Two of the surface layer materials 42 were prepared, and the hot press cushioning material 40 having the structure shown in
A hot press cushioning material 40 of Comparative Example 3 had the structure shown in
A hot press cushioning material of Comparative Example 4 had a stacked structure of eight sheets of kraft paper. Each sheet of kraft paper had a basis weight of 190 g/m2.
(Evaluation Method)
A compression test using a compression terminal was conducted for the hot press cushioning materials of Examples 1, 2 and Comparative Examples 1 to 4 to evaluate the amount of spot deformation and repeated usability.
Specifically, a compression terminal 51 having a spherical tip end as shown in
The hot press cushioning materials of Examples 1, 2 and Comparative Examples 1 to 4 were then pressed one hundred times. The press was performed under the following conditions. First, the hot press cushioning material was placed between heating platens. While being pressed with a pressure of 4 MPa, the hot press cushioning material was heated for 20 minutes from normal temperature to 230° C. The temperature of the hot press cushioning material was maintained at 230° C. for 40 minutes. Subsequently, the hot press cushioning material was cooled for 10 minutes to normal temperature. The pressure was released after the cooling. This was a single press cycle. The amount of spot deformation x that occurred in the thickness direction of the hot press cushioning material when the hot press cushioning material was pressed with a pressure of 0.5 MPa as described above was measured after a single press, 10 presses, and 100 presses. The result is shown in Table 1. In Table 1, “Initial” means the state before hot press.
(Evaluation Result)
Comparative Example 4 had excellent spot deformation properties, but was crushed by a single hot press and was not able to be used repeatedly.
Comparative Examples 1 to 3 had a structure that is conventionally used as a hot press cushioning material with excellent repeated usability. However, Comparative Examples 1 to 3 had a smaller amount of spot deformation than Comparative Example 4 and had poor conformability to fine unevenness.
Examples 1 and 2 included the nonwoven fabric-resin composite layer and the woven fabric-rubber composite layer both having voids. Examples 1 and 2 therefore had a larger amount of spot deformation than Comparative Examples 1 to 4. In Examples 1 and 2, the amount of spot deformation did not decrease so much from the initial amount of spot deformation even after 100 press cycles. Examples 1 and 2 thus had a large amount of spot deformation and therefore had excellent conformability to fine unevenness. Moreover, since a decrease in the amount of spot deformation from the initial value is small, Examples 1 and 2 had excellent repeated usability.
According to the examples of the present invention, it was thus confirmed that a hot press cushioning material having improved conformability to fine unevenness and capable of being repeatedly used can be implemented by impregnating a stack of a nonwoven fabric layer and a fabric layer with resin from the nonwoven fabric layer side to form a nonwoven fabric-resin composite layer and impregnating the stack with rubber from the woven fabric layer side to form a woven fabric-rubber layer.
The embodiments and examples disclosed herein are by way of example in all respects and should not be interpreted as restrictive. The scope of the present invention is defined by the claims rather than the above embodiments and examples, and the invention is intended to cover all modifications and equivalents included within the spirit and scope of the invention as defined by the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014-134795 | Jun 2014 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2015/068652 | 6/29/2015 | WO | 00 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2016/002705 | 1/7/2016 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 6514888 | Tanaka | Feb 2003 | B1 |
| 20050014437 | Yoshida | Jan 2005 | A1 |
| 20140120792 | Yoshida et al. | May 2014 | A1 |
| Number | Date | Country |
|---|---|---|
| 0 703 069 | Mar 1996 | EP |
| 1 084 821 | Mar 2001 | EP |
| H07156335 | Jun 1995 | JP |
| H0890577 | Apr 1996 | JP |
| 2007090796 | Apr 2007 | JP |
| 4183558 | Nov 2008 | JP |
| 4746523 | Aug 2011 | JP |
| 5341733 | Nov 2013 | JP |
| 20010070076 | Jul 2001 | KR |
| 2008065969 | Jun 2008 | WO |
| WO2008065969 | Jun 2008 | WO |
| 2009072463 | Jun 2009 | WO |
| Entry |
|---|
| Machine translation of WO2008065969, Yoshida, Jun. 2008. |
| Office Action for corresponding European Patent Application No. 15814064.0-1706, dated Nov. 7, 2017, 9 pages. |
| Number | Date | Country | |
|---|---|---|---|
| 20170129206 A1 | May 2017 | US |
