Cushioning material for heat pressing

Abstract

The present invention is capable of improving heat resistance; specifically, the present invention is firstly capable of suppressing corrosion of a hot plate even in cases where the hot plate is used at high temperatures, and is secondly capable of suppressing decrease in cushioning properties even in cases where the hot plate is repeatedly used at high temperatures.　Cushioning materials (1A to 1D) for hot pressing according to the present invention contain a fluorine rubber; and a composition of the fluorine rubber comprises a fluorine rubber component, a vulcanizing agent, an acid acceptor and a dehydration agent. The amount of the acid acceptor relative to a total of 100 parts by mass of the fluorine rubber component and the vulcanizing agent is larger than the amount of the dehydration agent.

Description

[Technical Field]

[0001] This invention relates to a cushioning material for heat pressing. More specifically, this invention relates to a cushioning material for heat pressing used when press molding or heat-compressing target products in the process of manufacturing printed circuit boards such as copper-clad laminates, flexible printed circuit boards, rigid-flex circuit boards, multilayer boards, and multilayer flexible printed circuit boards, as well as precision equipment parts such as insulating boards, credit cards, IC cards, liquid crystal display boards, ceramic laminates, melamine decorative boards, etc. (hereinafter referred to as "laminated boards" in this invention). [Background technology]

[0002] In the manufacturing of laminated boards such as printed circuit boards, the press molding and heat-compression bonding processes involve sandwiching the laminated board material 12, which is the object to be pressed, between two heating plates 13, 13, and applying constant pressure and heat, as shown in Figure 3. To obtain a highly accurate molded product, it is necessary to ensure that the heat and pressure applied to the laminated board material 12 are uniform across its entire surface during heat pressing. For this purpose, heat pressing is performed with a flat cushioning material 11 interposed between the heating plates 13 and the laminated board material 12. In some cases, a stainless steel mirror-finish plate may be interposed between the cushioning material 11 and the laminated board material 12.

[0003] Here, the general characteristics required of the cushioning material 11 include cushioning properties to absorb the irregularities of the heating plate 13 and the laminated material 12, in-plane uniformity to uniformly transfer temperature and pressure from the heating plate 13 to the laminated material 12 across the entire press surface, heat transfer properties to efficiently transfer heat from the heating plate 13 to the laminated material 12, and heat resistance to withstand the press temperature.

[0004] Such cushioning materials are available that utilize synthetic rubber. A typical example consists of a layer of woven or nonwoven fabric made of heat-resistant fibers such as glass fibers or aromatic polyamide fibers, laminated and integrated with a synthetic rubber layer. Furthermore, to provide release properties, it is known that a surface layer such as a fluororesin film is bonded and integrated onto the surface of the cushioning material.

[0005] Examples of such cushioning materials include Japanese Patent Publication No. 6-278153 (Patent Document 1). Patent Document 1 discloses a cushioning material for molding presses comprising a cushioning material body having a fluororubber layer and a surface layer, wherein the fluororubber layer contains a fluororubber raw material, an acid acceptor, and a vulcanizing agent. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 6-278153 [Overview of the project] [Problems that the invention aims to solve]

[0007] Although the cushioning material for molding presses described in Patent Document 1 uses an acid acceptor and a vulcanizing agent to improve heat resistance, there is a need to further improve heat resistance.

[0008] The cushioning material for molding presses described in Patent Document 1, when used at high temperatures, may generate hydrogen fluoride (a corrosive gas) from the fluororubber during use, potentially causing corrosion of the heating plate. Therefore, the cushioning material for molding presses described in Patent Document 1 incorporates a larger amount of acid absorber into the fluororubber to suppress hydrogen fluoride generation. However, even with a larger amount of acid absorber in the fluororubber, corrosion of the heating plate could still occur when used at high temperatures of 230°C to 250°C. Furthermore, the cushioning properties of the cushioning material for molding presses described in Patent Document 1 could significantly deteriorate when repeatedly used at high temperatures.

[0009] The present invention was made to solve the above-mentioned problems, and its purpose is to provide a cushioning material for hot pressing that can improve heat resistance, specifically, firstly, can suppress corrosion of the hot plate even when used at high temperatures, and secondly, can suppress a decrease in cushioning properties even when repeatedly used at high temperatures. [Means for solving the problem]

[0010] A cushioning material for a hot press according to one aspect of the present invention is a cushioning material for a hot press containing fluororubber, wherein the fluororubber composition comprises a fluororubber component, a vulcanizing agent, an acid absorber, and a water absorber. The acid absorber has the effect of neutralizing hydrogen fluoride, which is generated by the deterioration of fluororubber and causes corrosion of the hot plate. The water absorber has the effect of absorbing moisture contained in the fluororubber.

[0011] Preferably, the amount of water-removing agent relative to 100 parts by mass of the total fluororubber component and vulcanizing agent is greater than the amount of acid-receiving agent.

[0012] Preferably, the amount of water-removing agent relative to 100 parts by mass of the total fluororubber component and vulcanizing agent is 1.5 times or more the amount of acid-receiving agent.

[0013] Preferably, the total amount of the acid absorber and water absorber is 3 to 50 parts by mass relative to 100 parts by mass of the total amount of the fluororubber component and vulcanizing agent.

[0014] Preferably, the acid acceptor is magnesium oxide, zinc oxide, lead oxide, or dibasic phosphoric acid. lead It includes at least one selected from the group consisting of and hydrotalcite.

[0015] Preferably, the water-removing agent comprises at least one selected from the group consisting of calcium oxide, aluminum oxide, magnesium sulfate, and magnesium chloride.

[0016] Preferably, the acid acceptor is magnesium oxide and the water scavenger is calcium oxide.

[0017] Preferably, the mass ratio of magnesium oxide to calcium oxide is magnesium oxide:calcium oxide = 1:4 to 2:3.

[0018] Preferably, the magnesium oxide has a BET specific surface area of 80 m , ,

[0022] , , , / g or more and 300 m 2 / g or less. More preferably, the magnesium oxide has a BET specific surface area of 100 m 2 / g or more and 260 m 2 / g or less.

[0019] Preferably, the heat-resistant temperature of the cushion material for hot pressing is 250°C or higher and 300°C or lower.

Advantages of the Invention

[0020] According to the present invention, the heat resistance can be improved. Specifically, first, even when used at a high temperature, corrosion of the hot plate can be suppressed. Second, even when repeatedly used at a high temperature, a decrease in cushioning performance can be suppressed.

Brief Description of the Drawings

[0021] [Figure 1] It is a schematic diagram showing a cushion material for hot pressing according to an embodiment of the present invention. [Figure 2] It shows a plan view of an iron plate in an example. (A) shows a state where no corrosion or discoloration can be confirmed on the iron plate, (B) shows one where corrosion or discoloration can be confirmed on the hot plate, and (C) shows one where rust has progressed to the inside of the iron plate and corrosion or missing materials can be confirmed. [Figure 3] It is a diagram for explaining the hot pressing process.

Modes for Carrying Out the Invention

[0022] Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and their descriptions will not be repeated.

[0023] <Cushioning material for heat pressing> Figures 1(A) to 1(D) show specific configuration examples of the heat press cushioning material according to this embodiment. The configuration examples of the heat press cushioning materials 1A to 1D according to this embodiment will be described with reference to Figures 1(A) to 1(D), respectively. The heat press cushioning materials 1A to 1D of this embodiment contain fluororubber.

[0024] The heat-press cushioning material 1A shown in Figure 1(A) is a fluororubber sheet formed solely from a fluororubber layer 2. Alternatively, a surface layer made of paper, woven fabric, nonwoven fabric, synthetic resin film, etc., may be laminated to the front and back surfaces of the fluororubber layer 2.

[0025] The heat-press cushioning material 1B shown in Figure 1(B) comprises a nonwoven fabric layer 3 made of nonwoven fabric, two fluororubber layers 2 sandwiching the nonwoven fabric layer 3 from above and below, and a surface layer 4 made of synthetic resin film that is attached to the front and back surfaces of the two fluororubber layers 2.

[0026] The heat-press cushioning material 1C shown in Figure 1(C) comprises a base layer 5 of a fiber-rubber composite material, which is a woven fabric impregnated with fluororubber, and a surface layer 4 formed of a synthetic resin film, which is attached to the front and back surfaces of the fiber-rubber composite material base layer 5. Note that the fiber-rubber composite material of the base layer 5 contains fluororubber.

[0027] The heat-press cushioning material 1D shown in Figure 1(D) comprises two base layers 5 made of fiber-rubber composite material, an adhesive layer 6 made of fluororubber that bonds the two base layers 5 together, and a surface layer 4 made of synthetic resin film that is attached to the front and back surfaces of the two base layers 5. Note that the fiber-rubber composite material of the base layers 5 and the adhesive layer 6 contain fluororubber.

[0028] These heat-press cushioning materials 1A to 1D can be used at high temperatures, with a heat resistance temperature of 250°C to 300°C. If the operating temperature exceeds 300°C, the cushioning performance may significantly decrease with repeated use.

[0029] Thus, the fluororubber according to this embodiment includes, for example, a fluororubber sheet, fluororubber impregnated into a substrate, and a fluororubber adhesive. In other words, the fluororubber does not necessarily have to form a layer on its own, but may be impregnated into or attached to fibers or the like. Note that the heat-press cushioning materials 1A to 1D in Figures 1(A) to (D) are just examples, and the material is not limited to the above configuration as long as it has the fluororubber structure described below.

[0030] Next, we will explain in detail about fluororubber used as a cushioning material for heat pressing.

[0031] <Fluororubber> The fluororubber composition comprises a fluororubber component as a base material, a vulcanizing agent, an acid acceptor, and a water-removing agent.

[0032] Fluororubber components include various types such as polymers of fluorinated acrylates, copolymers of vinylidene fluoride, fluorinated silicon rubber, fluorinated polyester rubber, and copolymers of fluorinated dienes. However, the type is not particularly limited, and appropriate selections can be made from among these.

[0033] As the vulcanizing agent, known vulcanizing agents for fluororubber, such as organic peroxide-based vulcanizing agents, amine-based vulcanizing agents, and polyol-based vulcanizing agents, can be used. The vulcanizing agent is a compounding agent for vulcanizing fluororubber.

[0034] Fluororubber is usually compounded with an acid acceptor to neutralize hydrogen fluoride generated during the vulcanization reaction and to promote vulcanization. However, when fluororubber is used as a cushion material for a hot press, hydrogen fluoride is generated during use because it is used at high temperatures, which may lead to a decrease in the physical properties of the rubber and corrosion of the hot plate. Therefore, in this embodiment, an acid acceptor is compounded to neutralize hydrogen fluoride generated not only during vulcanization but also during use.

[0035] The acid acceptor is selected from the group consisting of, for example, magnesium oxide, zinc oxide, lead oxide, dibasic lead phosphate, and hydrotalcite. The acid acceptor may be used alone or two or more acid acceptors may be used in combination. In particular, the acid acceptor is preferably magnesium oxide.

[0036] When magnesium oxide is used as the acid acceptor, it is preferable to use highly active magnesium oxide having a BET specific surface area of 80 m 2 [[ID=?]] / g or more and 300 m 2 / g or less. More preferably, the magnesium oxide has a BET specific surface area of 100 m " 2 / g or more and 260 m 2 / g or less. Magnesium oxide having a BET specific surface area of 80 m 2 / g or more is highly active, so it has a great effect of neutralizing hydrogen fluoride generated during the use of the cushion material for the hot press. If the BET specific surface area exceeds 300 m 2 / g, the dispersibility in fluororubber may decrease. Incidentally, magnesium oxide having a BET specific surface area of less than 80 m 2 / g is low-active magnesium oxide.

[0037] The water scavenger absorbs moisture contained in the fluororubber. The water scavenger is selected from the group consisting of, for example, calcium oxide, aluminum oxide, magnesium sulfate, and magnesium chloride. The water scavenger may be used alone or two or more water scavengers may be used in combination. In particular, the water scavenger is preferably calcium oxide. When calcium oxide is used as the water scavenger, it is preferably in the form of a fine powder. It should be noted that there seems to be an error in line 8 of the original text where "80m " is incomplete. I have tried to translate it as best as possible based on the context.

[0038] The inventors conducted extensive research into the causes of corrosion of heating plates and concluded that simply incorporating an acid absorber is insufficient to prevent corrosion, and that moisture within the fluororubber plays a significant role in the corrosion. Therefore, they discovered the use of a water-removing agent to remove moisture from within the fluororubber.

[0039] The ratio of the total amount of acid acceptor and water absorber to 100 parts by mass of the total amount of fluororubber component and vulcanizing agent is preferably 3 to 50 parts by mass, and more preferably 10 to 30 parts by mass. If the total amount of acid acceptor and water absorber is less than 3 parts by mass, it may lead to a decrease in the physical properties of the rubber or corrosion of the heating plate. If the total amount of acid acceptor and water absorber is more than 50 parts by mass, desirable physical properties of the fluororubber, namely good properties such as cushioning and heat resistance, cannot be obtained, and the processability will be poor.

[0040] The amount of water-absorbing agent relative to 100 parts by mass of the total fluororubber component and vulcanizing agent is preferably greater than the amount of acid acceptor. Specifically, the amount of water-absorbing agent is preferably 1.5 times or more the amount of acid acceptor. If the amount of water-absorbing agent relative to 100 parts by mass of the total fluororubber component and vulcanizing agent is less than 1.5 times the amount of acid acceptor, the water-absorbing agent may not be able to sufficiently absorb the moisture in the fluororubber, and the heating plate may corrode.

[0041] Furthermore, when magnesium oxide is used as the acid acceptor and calcium oxide is used as the water remover, it is more preferable that the mass ratio of magnesium oxide to calcium oxide be magnesium oxide:calcium oxide = 1:4 to 2:3.

[0042] As described above, the fluororubber composition in this embodiment comprises a fluororubber component, a vulcanizing agent, an acid acceptor, and a water-removing agent. Conventional heat-press cushioning materials have a heat resistance temperature of 230°C to 250°C and could only be used at temperatures below that. However, by using the fluororubber composition of this embodiment, it is possible to use it even at high temperatures such as 250°C to 300°C, thereby improving heat resistance.

[0043] Specifically, the first effect is that by using the fluororubber composition of this embodiment, corrosion of the heating plate can be suppressed. This is thought to be because the generation of hydrogen fluoride (a corrosive gas) when the cushioning material for the heat press is used at high temperatures is suppressed by the acid absorber, while the moisture in the fluororubber can be removed by the water-removing agent.

[0044] Furthermore, corrosion of the heating plate is largely caused by moisture within the fluororubber. Therefore, instead of simply mixing the acid absorber and the water absorber, the corrosion of the heating plate can be further suppressed by using a larger amount of water absorber than the acid absorber. Specifically, by using an amount of water absorber equal to 1.5 times or more the amount of acid absorber per 100 parts by mass of the total fluororubber components and vulcanizing agent, corrosion of the heating plate can be effectively suppressed.

[0045] A second effect is that by using the fluororubber composition of this embodiment, the cushioning properties of the heat-press cushioning material can be maintained.

[0046] If the heating plate is coated to prevent corrosion, then corrosion of the heating plate does not need to be considered. However, the cushioning material for hot presses in this embodiment retains its cushioning properties even when repeatedly used at high temperatures, and can be effectively used even in hot presses where corrosion of the heating plate does not need to be considered.

[0047] Fluororubber can be optionally compounded with, for example, vulcanization accelerators, plasticizers, fillers, and other additives. [Examples]

[0048] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0049] <Regarding corrosion testing of heating plates> Table 1 shows the mass percentage of each raw material in Examples 1 to 5, and Table 2 shows the mass percentage of each raw material in Comparative Examples 1 to 5. Table 3 specifically lists each raw material in Tables 1 and 2. Table 4 shows the results of the corrosion test on the hot plate.

[0050] (Example 1) First, the raw materials for the fluororubber sheet were prepared: fluororubber as the base material, an acid acceptor, a water remover, and a vulcanization accelerator. The raw material fluororubber, Daiel G-716, already contains an appropriate amount of polyol-based vulcanizing agent in addition to the fluororubber component. As the acid acceptor, Kyowa Mag MF-150 (BET specific surface area 119 m²), a highly active magnesium oxide, was used. 2 ( / g) was used. Calcium oxide was used as a water-removing agent.

[0051] These raw materials were mixed in the proportions shown in Table 1, and then vulcanized at 185°C for 30 minutes under a pressure of 10 MPa. For secondary vulcanization, heating at 230°C for 5 hours under no pressure was performed to produce a fluororubber sheet with dimensions of 250 mm x 250 mm and a thickness of 2 mm.

[0052] (Example 2) The method for producing the fluororubber sheet in Example 2 is basically the same as in Example 1, but the calcium oxide used as a water-removing agent is different, as shown in Tables 1 and 3 below.

[0053] (Example 3) The method for producing the fluororubber sheet in Example 3 is basically the same as in Example 1, but as shown in Table 1 below, the acid acceptor is low-activity magnesium oxide, Magsalat #30 (BET specific surface area 42 m²). 2 The difference lies in the use of / g).

[0054] (Example 4) The method for producing the fluororubber sheet in Example 4 is basically the same as in Example 1. Furthermore, the same raw materials as in Example 1 were used, but the mass ratio of highly active magnesium oxide as an acid acceptor and calcium oxide as a water absorber differs, as shown in Table 1 below.

[0055] (Example 5) The method for producing the fluororubber sheet in Example 5 is basically the same as in Example 1. Furthermore, the same raw materials as in Example 3 were used, but the mass ratio of low-activity magnesium oxide as an acid absorber and calcium oxide as a water-removing agent differs as shown in Table 1 below.

[0056] The methods for producing the fluororubber sheets in Comparative Examples 1 to 5, shown below, are basically the same as those in Example 1, but differ from Example 1 in the following respects.

[0057] (Comparative Example 1) Comparative Example 1 did not contain a water-removing agent.

[0058] (Comparative Example 2) Comparative Example 2 did not contain an acid acceptor.

[0059] (Comparative Example 3) Comparative Example 3 used the same raw materials as Examples 1 and 4, but the mass ratio of the acid absorber to the water absorber was different. Specifically, the mass ratio of the acid absorber to the water absorber was acid absorber:water absorber = 4:1.

[0060] (Comparative Example 4) Comparative Example 4 used the same raw materials as Examples 1 and 4, but the mass ratio of the acid absorber and the water absorber was different. Specifically, the mass ratio of the acid absorber to the water absorber was 1:1.

[0061] (Comparative Example 5) Comparative Example 5 used zinc oxide in addition to highly active magnesium oxide as an acid acceptor.

[0062] [Table 1]

[0063] [Table 2]

[0064] [Table 3]

[0065] (Evaluation method) Instead of conducting corrosion tests on a hot plate, the following corrosion tests were performed on steel plates for the fluororubber sheets of Examples 1-5 and Comparative Examples 1-5. The test samples were applied to both the top and bottom surfaces of each fluororubber sheet, with a basis weight of 680 g / m². 2 The test used was a laminated version of "Conex KS680" (Teijin Limited), a needle-punched nonwoven fabric made of aromatic polyamide fibers. The test method involved sandwiching the test sample between two iron plates and continuously heating and pressurizing it from above and below. The iron plates were made of SS400 standard carbon steel, 1.5 mm thick and 320 mm square.

[0066] The heating and pressurizing conditions were set to a temperature of 270°C and a pressure of 2.5 MPa. Under these conditions, after 48 hours, samples were taken every 24 hours to check for corrosion of the iron plates. The results are shown in Table 4 below. In Table 4, "A" indicates that no corrosion or discoloration was observed on the iron plate, "B" indicates that discoloration due to rust was observed on the iron plate, and "C" indicates that rust had progressed to the interior of the iron plate and that missing parts due to corrosion were observed. An example of "A" is shown in Figure 2(A), an example of "B" is shown in Figure 2(B), and an example of "C" is shown in Figure 2(C). The presence or absence of discoloration of the iron plate was determined by visual inspection, specifically by the presence or absence of metallic luster on the iron plate.

[0067] [Table 4]

[0068] (Measurement results) As shown in Table 4, in Examples 1-3, where the mass ratio of acid absorber to water absorber was 1:4, and in Examples 4 and 5, where the mass ratio was 2:3, the iron plates were less susceptible to corrosion compared to Comparative Examples 1 and 5, which contained only an acid absorber, and Comparative Example 2, which contained only a water absorber.

[0069] Furthermore, although magnesium oxide was used as the acid absorber and calcium oxide as the water absorber, in Examples 1-3, where the mass ratio of the acid absorber to the water absorber was 1:4, and in Examples 4 and 5, where the mass ratio was 2:3, the iron plates were less susceptible to corrosion compared to Comparative Example 3, where the mass ratio was 4:1, and Comparative Example 4, where the mass ratio was 1:1. This indicates that it is preferable to use a mass ratio of magnesium oxide as the acid absorber and calcium oxide as the water absorber of 1:4 to 2:3.

[0070] As an acid acceptor, the BET specific surface area is 119 m². 2 Examples 1 and 4, which used highly active magnesium oxide at a concentration of / g, had a BET specific surface area of ​​42m². 2 Compared to Examples 3 and 5, which used low-activity magnesium oxide at / g, the iron plate was less susceptible to corrosion. This indicates that when using magnesium oxide as an acid acceptor, high activity is preferable to low activity.

[0071] Based on the above, this embodiment confirms that by blending an acid absorber and a water-removing agent with fluororubber, corrosion of the steel plate can be suppressed under heating and pressurizing conditions. Therefore, the hot press cushioning material of the present invention, which uses fluororubber blended with an acid absorber and a water-removing agent, can suppress corrosion of the hot plate even when used at high temperatures.

[0072] <About press durability testing> Table 5 shows the results of the press durability tests for Example 6 and Comparative Example 6.

[0073] (Example 6) The heat-press cushioning material of Example 6 has the configuration shown in Figure 1(D), comprising two fiber-rubber composite material base layers (cushioning material body), an adhesive layer for bonding the two base layers, and a surface layer (surface material) attached to the front and back surfaces of the two base layers. Therefore, to manufacture the heat-pressing cushioning material of Example 6, two cushioning material bodies, adhesive, and two surface materials are prepared.

[0074] Specifically, a glass woven fabric "T860" (manufactured by Unitika Ltd.) using bulky yarn as the base material for the cushioning material was prepared. This glass woven fabric is made of bulky yarn with a count of 305tex, consisting of 3200 E glass fibers (fiber diameter 6μm) for the weft, and unbulky yarn with a count of 135tex, consisting of 1600 E glass fibers (fiber diameter 6μm) for the warp, and is woven in a double weave with the weft and warp threads. This glass woven fabric has a weight of 850g / m 2 The glass fabric had a thickness of 1.02 mm and a porosity of 67%. On the other hand, an unvulcanized fluororubber solution was prepared by dissolving the unvulcanized fluororubber according to the formulation of Example 1 described above at a predetermined concentration in a solvent mixed with butyl acetate, methyl ethyl ketone, and acetic acid. After immersing the glass fabric in each unvulcanized fluororubber solution, each was squeezed with two rolls. Next, each glass fabric that had been impregnated with the unvulcanized fluororubber solution was thoroughly dried to remove the solvent. In this way, two cushion material bodies that would become the base layer were prepared.

[0075] As the adhesive layer, a substrate made of 0.2 mm thick glass cloth was prepared by coating both the upper and lower surfaces with unvulcanized fluororubber according to the formulation of Example 1.

[0076] As the surface layer material, a 0.2 mm thick glass cloth was used as the base material. An unvulcanized fluororubber adhesive according to the formulation of Example 1 was applied to the bonding side, and a polyimide resin was applied to the surface side. Two surface materials were prepared in this manner.

[0077] The two layers of cushion material described above were laminated with an adhesive in between, and a surface layer was laminated to the surface of the upper cushion material and the back surface of the lower cushion material. Then, a heat press was performed to vulcanize the base layer, adhesive layer, and unvulcanized fluororubber used for the surface layer, thereby integrating the entire structure. The thickness of the heat-press cushion material obtained in this way in Example 6 was 1.9 mm.

[0078] (Comparative Example 6) The method for producing the heat-press cushioning material in Comparative Example 6 was basically the same as in Example 6, but in Comparative Example 6, unvulcanized fluororubber with the formulation of Comparative Example 1 was used instead of unvulcanized fluororubber with the formulation of Example 1. The thickness of the heat-press cushioning material in Comparative Example 1 was 1.9 mm, the same as in Example 6.

[0079] (Evaluation method) Press durability tests were conducted on the hot press cushioning materials of Example 6 and Comparative Example 6 using 280 mm square samples. The pressing conditions were a temperature of 270°C and a pressure of 4.0 MPa. Specifically, the heating plate was heated from 25°C to 270°C over 40 minutes and maintained at that temperature for 30 minutes. After that, it was cooled by water cooling for 15 minutes while maintaining the pressure, and after a total of 85 minutes of pressurization, it was released without pressing for 1 minute. A 150t test press PEWF-15045 (manufactured by Kansai Roll Co., Ltd.) was used as the press machine.

[0080] The above press cycle was defined as one cycle. For the cushioning materials for hot pressing of the examples and comparative examples, pressing was performed before pressing (0 cycles), and then 1, 10, 100, 200, 300, and 400 times, and the cushioning properties were evaluated at each stage.

[0081] The size of the evaluation sample was 25 mm in diameter, and it was taken from a position at least 5 cm away from the edge of the 280 mm square sample pressed under the above conditions. The conditions for the cushioning performance evaluation test were a temperature of 230°C and a pressure of 4.0 MPa. Specifically, 0.05 kgf / cm². 2After preheating at 230°C for 2 minutes under pressure, the change in thickness of the evaluation sample was measured when the pressure was increased at a rate of 1 mm / min until the pressure reached 4.0 MPa. The test apparatus used was an Instron 5565 universal material tester (manufactured by Instron Japan Company Limited).

[0082] Cushioning performance was evaluated by measuring the change in thickness of the cushioning evaluation sample from before pressurization to when it was pressed at 4.0 MPa. A large change in thickness (μm) indicated high cushioning, while a small change indicated low cushioning. The results of the press durability test are shown in Table 5. In the case of the comparative example, the test was terminated because the cushioning performance deteriorated significantly after 200 presses.

[0083] [Table 5]

[0084] (Measurement results) As shown in Table 5, the hot-press cushioning material of Example 6 with the formulation of Example 1 generally exhibited higher cushioning properties compared to the hot-press cushioning material of Comparative Example 6 with the formulation of Comparative Example 1. No rapid decrease in cushioning properties was observed even after 400 presses, maintaining high cushioning performance. On the other hand, in Comparative Example 6, the cushioning properties significantly decreased after 200 presses. This indicates that Example 6, which includes both an acid acceptor and a dehydrating agent, exhibits improved heat resistance compared to Comparative Example 6, which contains only an acid acceptor.

[0085] The embodiments and examples disclosed herein should be considered in all respects as illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the embodiments and examples described above, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]

[0086] 1A, 1B, 1C, 1D: Cushioning material for hot pressing; 2: Fluororubber layer; 3: Nonwoven fabric layer; 4: Surface layer; 5: Base material layer; 6: Adhesive layer; 11: Cushioning material; 12: Laminate material; 13: Heating plate.

Claims

1. In a heat-press cushioning material containing fluororubber, The fluororubber composition is Fluororubber components, A vulcanizing agent for vulcanizing the aforementioned fluororubber, A hot press cushion comprising an acid acceptor for neutralizing hydrogen fluoride during vulcanization or use, the acid acceptor comprising at least one selected from the group consisting of magnesium oxide, zinc oxide, lead oxide, dibasic lead phosphate, and hydrotalcite, The fluororubber composition further comprises a water-absorbing agent, which is calcium oxide, that absorbs moisture contained in the fluororubber. The total amount of the acid absorber and the water absorber relative to 100 parts by mass of the fluororubber component and the vulcanizing agent is 3 to 50 parts by mass. A cushioning material for hot pressing, characterized in that the amount of the water-removing agent relative to 100 parts by mass of the total of the fluororubber component and the vulcanizing agent is greater than the amount of the acid-receiving agent.

2. The heat-press cushioning material according to claim 1, wherein the amount of the water-removing agent relative to 100 parts by mass of the total of the fluororubber component and the vulcanizing agent is 1.5 times or more the amount of the acid-receiving agent.

3. The cushioning material for hot pressing according to claim 1 or 2, wherein the acid-receiving agent is magnesium oxide and the water-removing agent is calcium oxide.

4. The heat-press cushioning material according to claim 3, wherein the mass ratio of magnesium oxide to calcium oxide is magnesium oxide:calcium oxide = 1:4 to 2:

3.

5. The magnesium oxide has a BET specific surface area of ​​80 m². ２ / g or more, 300m ２ A heat-press cushioning material according to claim 3 or 4, wherein the amount is less than or equal to / g.

6. The heat-resistant temperature of the heat-press cushioning material is 250°C or higher and 300°C or lower, according to any one of claims 1 to 5.

Images