JP4276425B2 - Releasable cushion sheet - Google Patents

Description

【００６５】
表１から明らかなように、多孔質ＰＴＦＥとシリコーンエラストマーから成る弾性層（サンプル１）はシリコーンエラストマー単体から成る弾性層（サンプル２）よりも耐破断特性及び耐引裂特性に優れている。また圧密ＰＴＦＥフィルムから成る離型層（サンプル３）も未延伸ＰＴＦＥフィルムから成る離型層（サンプル４）よりも耐破断特性及び耐引裂特性に優れている。
【００６６】
そのため弾性層（サンプル１）と圧密ＰＴＦＥ（サンプル３）又は未延伸ＰＴＦＥ（サンプル４）とを組み合わせれば、シリコーンエラストマー単体（サンプル２）と未延伸フィルム（サンプル４）を組み合わせたときよりも格段に耐破断特性及び耐引裂特性が向上する。特に弾性層（サンプル１）と圧密ＰＴＦＥ（サンプル３）を組み合わせたときが最も耐破断特性及び耐引裂特性に優れる。
【００６７】
実験例５
実験例１と同様にして得られる延伸多孔質ＰＴＦＥフィルムを重ねることなくそのまま、カレンダーロールを用いて加熱しながら加圧することにより（７０℃、２．４ｋＮ／ｃｍ）空孔を圧潰して、厚さ約１０μｍの圧密ＰＴＦＥフィルムを製造した。
【００６８】
この厚さ１０μｍの圧密ＰＴＦＥフィルムを使用する以外は、実験例１〜３と同様にして、離型性クッションシートを製造した。
【００６９】
【発明の効果】
本発明のクッションシートは、多孔質ＰＴＦＥ樹脂を有する弾性層とフッ素樹脂フィルムを使用しているため、接着剤を使用することなく弾性層と非多孔質フッ素樹脂フィルムとを確実に接合（接着）することができる。そのため耐久性（接合性）と柔軟性に優れたクッションシートを得ることができる。
【図面の簡単な説明】
【図１】図１は本発明のクッションシートの一例を示す概略断面図である。
【図２】図２は本発明のクッションシートの他の例を示す概略断面図である。
【図３】図３は本発明のクッションシートのさらに他の例を示す概略断面図である。
【図４】図４は実験例の製造方法を説明するための概略斜視図である。
【図５】図５は実験例の剥離試験方法を説明するための概略断面図である。
【図６】図６は実験例の引裂試験方法を説明するための概略斜視図である。
【符号の説明】
１ 弾性層
２ 離型層（離型性フィルム）
３ クッションシート[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a cushion sheet made of a releasable film (fluororesin film) and an elastic layer and excellent in releasability. The fluororesin film formed on the surface of the cushion sheet is useful for enhancing the releasability of the cushion sheet itself. Such a cushion sheet (releasing cushion sheet) is, for example, between the substrate and the heater. When a plurality of materials are laminated and pressure-bonded to each other, they are inserted between the substrate and the heater and used.
[0002]
[Prior art]
The fluororesin film [polytetrafluoroethylene (PTFE) film, etc.] constituting the surface of the cushion sheet has a low affinity with other materials, and is useful for imparting release properties to the cushion sheet. On the other hand, the adhesion to the elastic layer is poor. Therefore, it is essential to improve the bondability (adhesiveness) between the fluororesin film and the elastic layer.
[0003]
For example, a sheet in which one side of a fluororesin film is chemically etched and then an unvulcanized elastomer is laminated on the etched side has been proposed. However, chemical etching has a problem in productivity due to a decrease in treatment effect over time, and work using an etchant also has a problem in terms of safety, so various cushion sheets that do not use an etchant have been studied. .
[0004]
That is, various techniques for bonding a fluororesin film and an elastic layer with an adhesive layer have been proposed. For example, Patent Document 1 discloses a technique in which silica fine particles are interposed between a fluororesin film and a heat resistant rubber layer, the wettability between the fluororesin film and the heat resistant rubber layer is improved by the silica fine particles, and the peel strength is increased. Is disclosed. Patent Document 2 discloses a technique in which one surface of a fluororesin layer is modified by plasma treatment, and then a silane coupling agent is applied, and an unvulcanized elastomer composition is adhered to the coated surface and heated and pressurized. Has been. However, since the adhesive layer is generally hard, the flexibility and flexibility of the cushion sheet itself are poor.
[0005]
[Patent Document 1]
JP 2001-315248 A (Claim 1, paragraph 0020)
[Patent Document 2]
JP 2001-79948 A (Claim 1)
[0006]
[Problems to be solved by the invention]
The present invention has been made paying attention to the above circumstances, and its purpose is to use a release film (fluororesin film) and an elastic layer without using a special component for adhesion. It is in the point which constitutes a cushion sheet.
[0007]
Another object of the present invention is to provide a cushion sheet excellent in bondability between a release film (fluororesin film) and an elastic layer and excellent in flexibility.
[0008]
[Means for Solving the Problems]
As a result of intensive research in order to solve the above problems, the present inventors made a composite with porous polytetrafluoroethylene (PTFE) resin as an elastic layer laminated on a fluororesin film (release layer). It has been found that when an elastomer is used, the fluororesin film and the porous PTFE resin exhibit high bondability by firing, exhibit high durability against repeated compressive stress, and therefore an adhesive layer that becomes a hard layer can be omitted. The present invention has been completed.
[0009]
That is, the releasable cushion sheet of the present invention that has achieved the above-mentioned object includes a porous polytetrafluoroethylene resin (porous PTFE resin) and an elastic layer formed of an elastomer that fills the pores of the porous PTFE resin. ,
The release layer is composed of a fluororesin film laminated on at least one side of the elastic layer.
[0010]
The fluororesin film is preferably a polytetrafluoroethylene (PTFE) film. PTFE has a small friction coefficient and is advantageous as a release layer. In general, it is difficult to reduce the thickness of PTFE, but it is also possible to reduce the thickness of PTFE in the present invention.
[0011]
A particularly preferable fluororesin film is a consolidated body of expanded porous PTFE. If the PTFE is stretched and made porous and then consolidated, the fluororesin film can be thinned, which is advantageous for enhancing the flexibility of the releasable cushion sheet. Moreover, the intensity | strength of a fluororesin film can also be raised.
[0012]
A preferable thickness of the fluororesin film is, for example, about 1 to 50 μm.
[0013]
As the elastomer, silicone elastomers (for example, methyl silicone, phenyl silicone, etc.), fluorine elastomers (fluoro silicone, fluoroelastomer, perfluoroelastomer, etc.) and the like are desirable. These are advantageous for improving the heat resistance and releasability of the cushion sheet.
[0014]
The elastic layer and the release layer (fluororesin film) are bonded to each other by firing.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the illustrated examples, but may be implemented with appropriate modifications within a range that can meet the purpose described above and below. All of which are within the scope of the present invention.
[0016]
FIG. 1 is a schematic cross-sectional view showing a two-layer type releasable cushion sheet 3. Specifically, the cushion sheet 3 is composed of one elastic layer 1 and one release layer 2. The mold layer 2 is composed of a single fluororesin film. The elastic layer 1 is formed of a porous polytetrafluoroethylene resin (porous PTFE resin) and an elastomer, and the elastomer fills a gap (hole portion) of the porous PTFE resin (hereinafter referred to as this elastic layer). Layer 1 may be referred to as a specific elastic layer).
[0017]
Such a cushion sheet 3 is rich in affinity because both the porous PTFE resin constituting the specific elastic layer 1 and the fluororesin 2 constituting the release layer 2 are fluororesins. Therefore, it can join (adhesion) by baking (heating), making it closely_contact | adhere, and the compression durability of the cushion sheet 3 can be ensured. Moreover, since the elastic layer 1 and the fluororesin film (release layer) 2 can be directly joined (adhered) without an adhesive layer, a cushion sheet 3 having excellent flexibility can be obtained. it can. Further, since the elastic layer 1 is reinforced with a porous PTFE resin, the elastic layer 1 can increase the breaking strength and tear strength.
[0018]
As long as at least one surface (outer surface) is formed of the release layer 2, the cushion sheet 3 of the present invention is not particularly limited in layer structure, and may have a three-layer structure or more in addition to the two-layer structure. Good. For example, FIG. 2 is a schematic cross-sectional view showing an example of a three-layer type. Specifically, release layers 2 are laminated on both sides of one specific elastic layer 1. When the cushioning sheet 3 is used as a cushioning material when a laminated material is inserted and pressure-bonded between the heater and the substrate, the release layer 2 is formed on both sides, so that the releasability of the material and the heater Alternatively, both of the mold releasability with respect to the substrate can be secured.
[0019]
Further, the elastic layer 1 and the release layer 2 do not have to be single layers, and a plurality of elastic layers may overlap to constitute one elastic layer, or a plurality of release layers may overlap to form one release layer. A mold layer may be configured.
[0020]
For example, FIG. 3 is a schematic cross-sectional view showing another example of the three-layer type, which is the same as the example of FIG. 2 in that the release layer 2 is laminated on both surfaces of the specific elastic layer 1. In this example, the specific elastic layer 1 in the center forms one specific elastic layer 1 by joining (adhering) elastic layers 1a and 1b that are physically different from each other. This is different from the second example. As will be described later, such a cushion sheet 3 is advantageous for easily and reliably manufacturing a cushion sheet of a three-layer type (more correctly, a type in which the release layer 2 is formed on both sides).
[0021]
Further, the cushion sheet 3 of the present invention is not necessarily formed only from the specific elastic layer 1 and the release layer 2, for example, the back surface of the cushion sheet in FIG. 1 (the surface on which the release layer 2 is not laminated). ) Or another elastic layer (ordinary elastic layer) different from the specific elastic layer 1 may be formed between the elastic layers 1a and 1b in FIG. Even in such a layer structure, the specific elastic layer and the normal elastic layer can be bonded (adhered) by utilizing the affinity between the elastomer forming the specific elastic layer and the normal elastic layer. The flexibility of the cushion sheet can be secured.
[0022]
In the present invention, the thickness of the fluororesin film forming the release layer 2 is not particularly limited, but the thinner the thickness, the more flexible the cushion sheet 3 is, and the better cushioning properties are preferable. Further, the thinner the fluororesin film, the higher the followability to the elastic layer 1 when the cushion sheet 3 is bent, and the peeling between the fluororesin film 2 and the elastic layer 1 can be prevented. The thickness of the preferable fluororesin film 2 is, for example, 1 mm or less, more preferably 0.1 mm (100 μm) or less, further preferably 50 μm or less, particularly 10 μm or less. In addition, since manufacture of a fluororesin film becomes difficult, so that it is thin, the said thickness is about 1 micrometer or more normally.
[0023]
Further, the thickness of the release layer 2 is, for example, 1 mm or less, more preferably 0.1 mm (100 μm) or less, further preferably 50 μm or less, particularly 10 μm or less, from the same viewpoint as in the case of the fluororesin film. desirable. When the release layer 2 is formed of a plurality of fluororesin films, the thickness of the release layer 2 is controlled within the above range by setting the thickness of the fluororesin film to be thinner than the above range. Can do.
[0024]
The thickness of the cushion sheet 3 is not particularly limited as long as the cushioning property can be ensured, and can be appropriately selected according to the application. The thickness can be selected from a range of, for example, about 0.1 mm or more (particularly 0.3 mm or more) or 20 mm or less (for example, 10 mm or less, particularly 5 mm or less).
[0025]
In the present invention, as the porous PTFE resin constituting the elastic layer 1, an expanded porous PTFE resin obtained by stretching PTFE can be used. The stretching may be uniaxial stretching or biaxial stretching. Microscopically, uniaxially stretched porous PTFE resin has fine island-like nodes (folded crystals) that are substantially perpendicular to the stretching direction, and interdigital fibrils (the folded crystals are stretched). Is characterized in that the linear molecular bundles melted and drawn out by (1) are oriented in the stretching direction. Biaxially-stretched porous PTFE has a cobweb-like fibrous structure in which fibrils spread radially, nodes that connect the fibrils are dotted in islands, and there are many spaces divided between the fibrils and the nodes. There is a microscopic feature.
[0026]
The porosity of the porous PTFE can be appropriately adjusted according to the draw ratio and the like, and is, for example, 30% or more (preferably 50% or more, more preferably 70% or more), 95% or less (preferably 93% or less, further Preferably, it is about 90% or less. The greater the porosity, the easier the elastomer will enter. Moreover, since the amount of elastomer that fills the gap can be increased as the porosity increases, the elasticity of the cushion sheet 3 can be increased. On the other hand, the smaller the porosity is, the larger the amount (area) of porous PTFE exposed on the surface of the elastic layer can be, so that the bondability (adhesiveness) with the elastic layer (fluororesin film) 2 can be improved. .
[0027]
The porosity is determined by measuring the mass W of the porous PTFE and the apparent volume V including the pores, and the bulk density D (D = W / V: unit is g / cm). ^Three ) And density D when no pores are formed at all. _standard (2.2 g / cm for PTFE resin ^Three ) And can be calculated based on the following formula.
[0028]
Porosity (%) = [1- (D / D _standard ] X 100
The average pore diameter of the porous PTFE can be appropriately adjusted according to the draw ratio and the like, and is, for example, about 0.05 to 5 μm, preferably about 0.5 to 1 μm. The larger the average pore diameter, the easier the elastomer can enter, while the strength of the resulting elastic layer 1 tends to decrease. The average pore diameter can be measured using a Coulter Poire meter manufactured by Coulter Electronics.
[0029]
The porous PTFE resin is often in the form of a film. When the porous PTFE resin is in the form of a film, it is common to use a plurality of laminated layers in order to secure a thickness for securing the cushioning property of the elastic layer 1.
[0030]
The elastomer constituting the elastic layer 1 is not particularly limited as long as it can penetrate into the pores of the porous PTFE and impart elasticity, and examples thereof include natural rubber elastomers, synthetic rubber elastomers (isoprene elastomers, chloroprene elastomers, butadienes). Type elastomers, styrene-butadiene copolymer elastomers, nitrile elastomers, acrylic elastomers, fluorine elastomers, silicone elastomers, sulfide elastomers, urethane elastomers, phosphazene elastomers), thermoplastic elastomers, etc. Can be used, preferably chloroprene elastomer, styrene-butadiene copolymer elastomer, nitrile elastomer, fluorine elastomer, silicone elastomer , Urethane elastomer, such as phosphazene-based elastomers may be used.
[0031]
A particularly preferred elastomer is an elastomer having excellent heat resistance. An elastomer having excellent heat resistance is particularly advantageous when the resulting cushion sheet 3 is used as a cushion sheet for pressure bonding with a heater. Examples of the elastomer having excellent heat resistance include silicone elastomers and fluorine elastomers.
[0032]
Examples of silicone elastomers include crosslinked organopolysiloxanes having a methyl-silicon skeleton (such as methylsilicone elastomers), and crosslinked organopolysiloxanes having an aromatic hydrocarbon-silicon skeleton (such as phenylsilicone elastomers). Is mentioned. Examples of the fluorinated elastomer include, for example, a cross-linked polyfluoromethylene in which hydrogen atoms may remain (fluoroelastomer), and a cross-linked polyfluoromethylene in which all hydrogen atoms are substituted with fluorine atoms (perfluoroelastomer). ), A crosslinked product of an organopolysiloxane having a fluoroalkyl group-silicon skeleton [fluorosilicone elastomer; for example, an elastomer having a bond structure of dimethylsiloxane and methyltrifluoropropylsiloxane, a fluorinated polyether skeleton being silicone-crosslinked Elastomers (for example, “SIFEL”, a trade name of Shin-Etsu Chemical Co., Ltd.)] and the like.
[0033]
The fluororesin film that forms the release layer 2 is a film made of a fluororesin and has excellent releasability (non-adhesiveness) and PTFE that forms the elastic layer 1 and firing (heating) Various films can be used as long as they have heat resistance to the extent that they can be bonded together. For example, as a fluorine-based resin, a vinyl-based monomer in which all hydrogen atoms are substituted with halogen atoms (hereinafter referred to as fluorine-containing perhalomonomer), for example, fluorine-containing perfluoroethylene such as tetrafluoroethylene and chlorotrifluoroethylene. Haloalkylenes; fluorine-containing perhaloalkylene propylenes such as hexafluoropropylene; fluorine-containing perhalovinyl ethers such as trifluoromethyl vinyl ether can be selected from homopolymers or copolymers. The copolymer may be copolymerized with other copolymer components as long as the above properties required for a fluororesin film can be satisfied. Examples of such copolymer components include alkylenes ( In particular, ethylene) is frequently used. Since the fluororesin as described above is excellent in releasability (non-adhesiveness), it can be used as the fluororesin of the present invention if one that does not carbonize at the firing temperature (about 327 ° C.) is selected. it can.
[0034]
Preferred fluororesins include homopolymers of fluorine-containing perhaloalkylenes (PTFE, polychlorotrifluoroethylene, etc.), copolymers of fluorine-containing perhalomonomers [preferably PTFE and other fluorine-containing perhalomonomers. Copolymer, such as tetrafluoroethylene-hexafluoropropylene copolymer (PFEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA)], copolymer of fluorine-containing perhaloalkylenes and alkylenes It can be selected from a polymer [tetrafluoroethylene-ethylene copolymer (PETFE) and the like]. More preferable fluororesins are PTFE, such as PTFE, PFEP, and PFA. PFEP and PFA are advantageous because they have excellent bondability (adhesiveness) to the elastic layer. On the other hand, although PTFE is inferior in bondability (adhesiveness), it is advantageous as a release layer in that it has a small friction coefficient. In general, it is difficult to reduce the thickness of PTFE, but in the present invention, it is also possible to reduce the thickness of PTFE by using consolidated PTFE as will be described later.
[0035]
In general, the fluororesin film can be obtained by once melting the resin and then extruding it from a die or the like to form a film, but PTFE cannot be melted or formed into a film. Therefore, when PTFE is selected as the fluororesin, as the PTFE film, a PTFE resin molded body obtained by sintering PTFE molding powder is thinly cut (referred to as an unstretched PTFE resin film), or once PTFE. It is desirable that the molded body in which the fine powder is made into a paste is stretched and then the stretched porous PTFE resin is compressed and consolidated (referred to as a consolidated PTFE resin film). The consolidated PTFE resin film is superior in breaking strength and tear strength as compared to an unstretched PTFE resin film. Therefore, a thin layer of the PTFE film can be easily achieved.
[0036]
The porosity of the consolidated PTFE film is, for example, about 30% or less (including 0%), preferably about 20% or less, and more preferably about 10% or less.
[0037]
In the present invention, the release layer 2 is generally formed of one fluororesin film, but if necessary, one release layer 2 may be formed from a plurality of fluororesin films. In this case, it is not excluded to superimpose a plurality of one (same type) fluororesin films, but it is preferable to superimpose a plurality of two or more different fluororesin films. When stacking two or more types, out of the release layer Elastic layer side surface Is used for the fluororesin film constituting the outer surface of the mold release layer (PFEP film, PFA film, etc.). It is desirable to use a fluororesin film (such as a PTFE film) having excellent releasability.
[0038]
The fluororesin films constituting the release layer 2 can be joined (adhered) by firing (heating).
[0039]
The releasable cushion sheet 3 as described above can be manufactured as follows. For example, the cushion sheet shown in FIG. 1 is manufactured by separately manufacturing a porous PTFE resin layer serving as a base of the elastic layer 1 and a non-porous fluororesin film used for the release layer 2, and then firing them in close contact ( Heating) and then filling the gaps (holes) of the porous PTFE resin layer with an elastomer. The reason why the elastomer is filled (impregnated) after firing (heating) is to prevent the elastomer from being deteriorated by firing (heating).
[0040]
The firing (heating) temperature is preferably equal to or higher than the melting point of PTFE, specifically 327 ° C. or higher, particularly 350 ° C. or higher. If the firing temperature is too high, the porous PTFE resin layer (elastic layer) and / or the fluororesin film (release layer) deteriorates. Therefore, the firing temperature is preferably 400 ° C. or less, particularly preferably 380 ° C. or less.
[0041]
The method for filling the gaps (pores) in the porous PTFE resin layer with an elastomer is not particularly limited. For example, a liquid material (solution, slurry) containing raw rubber before crosslinking, a crosslinking agent (curing agent), and, if necessary, a solvent. And the like, followed by crosslinking (curing), and a method of impregnating the porous PTFE resin with an elastomer made into a low-viscosity liquid material by dissolution and / or melting.
[0042]
The porous PTFE resin layer used for the elastic layer 1 is usually a laminate of a plurality of porous PTFE resin films and bonded (adhered) by sintering (heating). The thickness of the elastic layer 1 can be adjusted by laminating a plurality of porous PTFE resin films.
[0043]
Further, when a plurality of fluororesin films forming the release layer 2 are laminated, they may be bonded to each other by sintering (heating).
[0044]
Other cushion sheets 3 can also be manufactured by appropriately changing the manufacturing method of FIG. 1 according to the seat configuration. For example, the cushion sheet 3 shown in FIG. 2 is bonded (adhered) by laminating a release layer (fluororesin film) 2 on both surfaces of a porous PTFE resin layer serving as a base of the elastic layer 1 and then firing (heating) it. Then, it can be manufactured by filling the gaps in the porous PTFE resin layer with an elastomer.
[0045]
Further, the cushion sheet 3 shown in FIG. 3 includes, for example, two sheets having the same layer configuration as the cushion sheet of FIG. 1 (that is, a sheet composed of the elastic layer 1a / release layer 2 and an elastic layer 1b / release layer 2). Prepared, but the elastomer in the elastic layers 1a and 1b may be uncrosslinked), and then the two sheets are laminated with the elastic layers 1a and 1b facing each other and heated to an appropriate temperature. The elastic layers 1a and 1b can be bonded (adhered) together by welding them together or by cross-linking uncrosslinked elastomer. According to such a manufacturing method, although the release layer 2 is formed on both sides of the cushion sheet 3, the elastic layer 1 can be easily filled (impregnated) with the elastomer, and its efficiency can be increased. .
[0046]
The cushion sheet 3 of the present invention is excellent in releasability and also excellent in durability and flexibility, so that it can be suitably used for a wide range of applications, particularly suitable for a cushion sheet in a material crimping operation with a heater. Can be used for
[0047]
【Example】
EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. Of course, it is possible to implement them, and they are all included in the technical scope of the present invention.
[0048]
Experimental example 1
[Stretched porous PTFE film]
A paste resin is obtained by mixing 22 parts by mass of solvent naphtha with 100 parts by mass of polytetrafluoroethylene powder (fine powder) obtained by emulsion polymerization, and the paste resin is formed into a film. Is heated to a temperature higher than the boiling point of the solvent naphtha (200 ° C in this experimental example) to evaporate and remove the solvent naphtha, and then in the take-off direction at a temperature below the melting point of polytetrafluoroethylene (300 ° C in this experimental example). The film was biaxially stretched 2 times and 10 times in the direction perpendicular to the take-off direction to produce a stretched porous PTFE film having a thickness of 50 μm and a porosity of 80%. The stretching was performed at a speed at which the film extended at a rate of 10% or more per second (about 10% in this experimental example).
[0049]
[Consolidated PTFE film]
After the two porous PTFE films are overlaid, the pores are crushed by applying pressure while heating using a calender roll (70 ° C., 2.4 kN / cm), and a consolidated PTFE film having a thickness of about 20 μm is obtained. Manufactured.
[0050]
[Releasable cushion sheet]
As shown in FIG. 4, the above-mentioned compacted PTFE film 2 is wound once around a stainless steel hollow mandrel 4 having a diameter of 1,000 mm and a length of 1,500 mm. (See Fig. 4a). Next, the stretched porous PTFE film 6 was wound thereon 30 times. After cutting the surplus part, the cut end was fixed to the same position as the above with the double-sided adhesive tape 5b (refer FIG. 4b). Thereafter, this cylindrical laminate 7 was put in an oven and baked (heated) at a temperature of 365 ° C. for 60 minutes. After firing, the cylindrical laminate 7 was taken out of the oven and cooled to room temperature. The laminated body 7 is opened from the place fixed with the double-sided adhesive tape, and then the ends of the four sides are cut and removed, whereby a sheet (300 mm long × 300 mm wide × 1.0 mm thick) having a consolidated PTFE film on one side ( A) was obtained.
[0051]
Separately, the main component of the two-component reaction curing type silicone elastomer (manufactured by Shin-Etsu Chemical Co., Ltd .; trade name “KE1031”) and the curing agent are mixed at a ratio of 1: 1 (mass ratio), and the tray has a depth of 1 mm or more. Put in. The sheet (A) was placed in this tray, and the entire sheet (A) was completely immersed and left at room temperature for about 1 hour. After visually confirming that the mixture is impregnated in the entire pores of the sheet (A) (after the impregnation is referred to as the sheet (B)), the sheet (B) is taken out, and the excess adhered to the surface The appropriate mixture was wiped off. At this stage, a slight mixture that could not be wiped off adhered to the surface of the consolidated PTFE portion of the sheet (B). This sheet (B) was left in an oven at a temperature of 80 ° C. for 180 minutes to cure the mixture. The silicone elastomer adhering to the consolidated PTFE surface before curing could be easily removed after curing. As described above, a releasable cushion sheet (length 300 mm × width 300 mm × thickness 1.0 mm) having a consolidated PTFE film having a thickness of 20 μm on one surface was obtained.
[0052]
The releasability of the obtained sheet was evaluated as follows.
[0053]
[Releasability]
By cutting the cushion sheet, four sample sheets having a length of 100 mm and a width of 25 mm were obtained. As shown in FIG. 5, a stainless plate 10 having a length of 50 mm × width of 25 mm × thickness of 0.3 mm was sandwiched between two sample sheets 11. At this time, the stainless steel plate is sandwiched between the short side and the long side on both sides of the stainless steel plate so as to overlap the short side and the long side on both sides of the sample sheet 11, respectively. The adhesion test laminate 12 was manufactured by applying a load of 0.1 MPa and holding for 24 hours.
[0054]
A laminate 12 for adhesion test is prepared for both the case where the stainless steel plate 10 is sandwiched between the two surfaces of the compacted PTFE (FIG. 5a) and the case where the stainless steel plate 10 is sandwiched between the one surface of the elastomer-impregnated layer (FIG. 5b). As shown to 5c, the sheet | seat 11 was peeled from the non-lamination side edge part of the laminated board 12 (tensile speed: 10 mm / min), and adhesive strength was investigated.
[0055]
The adhesive strength of one surface of the elastomer-impregnated layer was 0.8 N / 25 mm, whereas the adhesive strength of the consolidated PTFE 2 surface was 0 N / 25 mm, which was excellent in releasability.
[0056]
Experimental example 2
In the same manner as in Experimental Example 1, two sheets (B) before curing impregnated with the mixture (elastomer) were prepared. These sheets (B) were superposed with their porous PTFE surfaces facing each other. In this state, the consolidated PTFE surface forms the outer surface of the overlapped sheet (B). Next, by curing the mixture in the same manner as in Experimental Example 1, a releasable cushion sheet (length 300 mm × width 300 mm × thickness 2.0 mm) having a consolidated PTFE film with a thickness of 20 μm on both sides as shown in FIG. )
[0057]
Experimental example 3
A releasable cushion sheet (length 300 mm × width 300 mm × thickness 0) having a compacted PTFE film having a thickness of 20 μm on one side is the same as in Experimental Example 1 except that the number of windings of the stretched porous PTFE film is 15 times. .54 mm). The compression durability (strength) of this cushion sheet was evaluated as follows.
[0058]
That is, a sample sheet obtained by cutting the cushion sheet into a length of 50 mm and a width of 50 mm was sandwiched between a pair of platens heated to a temperature of 180 ° C. A 10 MPa compressive load was applied to the sample sheet through this platen for 1 minute and then unloaded. This loading / unloading operation was repeated 10 times, and the appearance of the sample was visually confirmed.
[0059]
The elastic layer (layer consisting of expanded porous PTFE and impregnated silicone elastomer) and the consolidated PTFE film are free from cracks and cracks, and there is no separation between the elastic layer and the consolidated PTFE film, resulting in excellent bonding (adhesion) strength. It was.
[0060]
Experimental Example 4
The breaking strength and tear strength of the following four samples were measured by the following tensile test and tear test.
[0061]
[sample]
Sample 1 (elastic layer):
Elastic layer (thickness: 0.52 mm) obtained by peeling the consolidated PTFE film from the cushion sheet obtained in Experimental Example 3
Sample 2 (elastic layer):
Commercially available silicone elastomer (thickness: 0.54 mm, manufactured by Togawa Rubber Co., Ltd., trade name “silicone rubber K-125”)
Sample 3 (release layer):
A consolidated PTFE film (thickness: 0.042 mm) obtained in the same manner as in Experimental Example 1 except that four stretched porous PTFE films are stacked.
Sample 4 (release layer):
Commercial unstretched PTFE film (sintered PTFE film) (thickness: 0.55 mm, “Yodoflon PTFE film” manufactured by Yodogawa Hutec Co., Ltd.)
[Tensile test]
Samples 1 to 4 were punched into a dumbbell shape No. 3 defined by JIS K6251. The dumbbell test piece was pulled at a pulling speed of 200 mm / min, and the strength when the test piece broke was examined.
[0062]
[Tear test]
As shown in FIG. 6, samples 1 to 4 were cut into a rectangular shape having a length of 100 mm and a width of 50 mm, and a slit having a length of 50 mm was formed from the center of the short side of the rectangle toward the center of the sample. Both sides of the slit were pinched and pulled at a pulling speed of 200 mm / min so as to be in opposite directions, and the load when the test piece was torn was measured.
[0063]
The results are shown in Table 1 below.
[0064]
[Table 1]

[0065]
As can be seen from Table 1, the elastic layer (sample 1) made of porous PTFE and silicone elastomer is superior to the elastic layer (sample 2) made of silicone elastomer alone in terms of fracture resistance and tear resistance. Further, the release layer (sample 3) made of a consolidated PTFE film is also superior in fracture resistance and tear resistance than the release layer (sample 4) made of an unstretched PTFE film.
[0066]
Therefore, if the elastic layer (sample 1) and the consolidated PTFE (sample 3) or unstretched PTFE (sample 4) are combined, the silicone elastomer alone (sample 2) and the unstretched film (sample 4) are combined. In addition, the fracture resistance and tear resistance are improved. In particular, the combination of the elastic layer (sample 1) and the consolidated PTFE (sample 3) is most excellent in fracture resistance and tear resistance.
[0067]
Experimental Example 5
By stretching the porous porous PTFE film obtained in the same manner as in Experimental Example 1 while heating it using a calender roll as it is (70 ° C., 2.4 kN / cm), the pores are crushed and thickened. A consolidated PTFE film having a thickness of about 10 μm was produced.
[0068]
A releasable cushion sheet was produced in the same manner as in Experimental Examples 1 to 3, except that this 10 μm thick consolidated PTFE film was used.
[0069]
【The invention's effect】
Since the cushion sheet of the present invention uses an elastic layer having a porous PTFE resin and a fluororesin film, the elastic layer and the non-porous fluororesin film are reliably bonded (adhered) without using an adhesive. can do. Therefore, a cushion sheet excellent in durability (bondability) and flexibility can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing an example of a cushion sheet of the present invention.
FIG. 2 is a schematic sectional view showing another example of the cushion sheet of the present invention.
FIG. 3 is a schematic sectional view showing still another example of the cushion sheet of the present invention.
FIG. 4 is a schematic perspective view for explaining a manufacturing method of an experimental example.
FIG. 5 is a schematic cross-sectional view for explaining a peeling test method of an experimental example.
FIG. 6 is a schematic perspective view for explaining a tear test method of an experimental example.
[Explanation of symbols]
1 Elastic layer
2 Release layer (Releasable film)
3 Cushion seat

Claims (10)

An elastic layer formed of a porous polytetrafluoroethylene resin and an elastomer that fills the pores of the porous polytetrafluoroethylene resin;
A releasable cushion sheet comprising a release layer made of a fluororesin film laminated on at least one surface of the elastic layer. The releasable cushion sheet according to claim 1, wherein the fluororesin film is a polytetrafluoroethylene film. The releasable cushion sheet according to claim 1, wherein the fluororesin film is a consolidated body of stretched porous polytetrafluoroethylene. The releasable cushion sheet according to any one of claims 1 to 3, wherein the release layer is a single layer or a laminate of one kind of fluororesin film. The release layer is a laminate of two or more fluororesin films,
The fluororesin film constituting the elastic layer side surface of the release layer is formed of a tetrafluoroethylene-hexafluoropropylene copolymer and / or a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer,
The releasable cushion sheet according to any one of claims 1 to 3, wherein the fluororesin film constituting the outer surface of the release layer is formed of polytetrafluoroethylene. The releasable cushion sheet according to any one of claims 1 to 5, wherein the fluororesin film has a thickness of 1 to 50 µm. The releasable cushion sheet according to claim 1, wherein the elastomer is a silicone elastomer and / or a fluorine elastomer. The releasable cushion sheet according to claim 7, wherein the silicone elastomer is methyl silicone and / or phenyl silicone. The releasable cushion sheet according to claim 7 or 8, wherein the fluoroelastomer is at least one selected from fluorosilicone, fluoroelastomer, and perfluoroelastomer. The releasable cushion sheet according to any one of claims 1 to 9, wherein the elastic layer and the release layer are bonded by baking.

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