Sealing material

Abstract

A sealing material 1a is provided with a foam body 10. The foam body 10 includes an olefin resin and a thermoplastic elastomer. The sealing material 1a comprises a first portion 11 having a thickness of 50 μm including the surface of the sealing material 1a. The first portion 11 has a tensile elastic modulus E11 of 0.35-230 MPa. A mixture of 5 mass% of the foam body 10 and 95 mass% of polypropylene (virgin PP) is molded to a thickness of 200 µm to obtain a sheet-like sample. The area percentage of a portion in which a heterogeneous part exists in a 1 cm2 area in the plan view of the sample is 10% or less.

Description

sealing material

[0001] The present invention relates to a sealing material.

[0002] BACKGROUND ART Conventionally, sealing materials having a foam containing an olefin resin are known.

[0003] For example, Patent Document 1 describes a polyolefin resin foam sheet, which is produced by foaming a polyolefin resin composition containing a polyolefin resin and a pigment. This polyolefin resin foam sheet has a 25% compressive stress of 80 to 1400 kPa, a pigment content of 0.60 to 10.00 parts by mass per 100 parts by mass of resin, and a density of 0.10 to 0.60 g / cm. 3 and the gel fraction is 25 to 60% by mass. The polyolefin resin composition is irradiated with an electron beam under specified conditions to cause crosslinking. A pressure-sensitive adhesive tape using this foamed sheet as a substrate and having a pressure-sensitive adhesive layer on one or both sides of the foamed sheet can be used as a sealant to prevent moisture and the like from penetrating into the main body of an electronic device.

[0004] Patent Document 2 describes a polyolefin resin foam sheet, which has a flexural modulus of 150 kPa or less and a shrinkage rate in the plane direction of 5% or less when cured at 120°C for 1 hour. According to the examples, a sheet-shaped resin composition obtained by melt-kneading random PP, EPDM, TPO, and LLDPE in predetermined amounts is irradiated with an electron beam on both sides to crosslink the composition. Pressure-sensitive adhesive tapes using this foam sheet as a substrate can be suitably used as sealing materials for electronic devices.

[0005] JP 2019-218563 A JP 2020-139087 A

[0006] According to the techniques described in Patent Documents 1 and 2, the resin composition for the foam is crosslinked by electron beam irradiation, and the crosslinked product is thought to be present in the polyolefin resin foam sheet. This is not advantageous from the viewpoint of recycling the foam. In addition, the water-stopping property of the sealant containing the foam and the ease of installation of the sealant may be important in some cases.

[0007] Therefore, the present invention provides a sealing material that is advantageous from the viewpoints of ease of recycling, watertightness, and ease of installation work.

[0008] The present invention provides a sealing material, comprising a foam containing an olefin resin and a thermoplastic elastomer, the sealing material including a first portion having a thickness of 50 μm including a surface of the sealing material, the first portion having a tensile modulus of 0.35 to 230 MPa, and a sheet-like sample obtained by molding a mixture of 5 mass % of the sealing material and 95 mass % of polypropylene to a thickness of 200 μm, the sheet-like sample having a thickness of 1 cm in a plan view. 2 The ratio of the area occupied by the heterogeneous portion forming the dispersed phase to the total area of ​​the sealing material is 10% or less.

[0009] The above-mentioned sealing material is advantageous in terms of ease of recycling, watertightness, and ease of installation work.

[0010] FIG. 1 is a cross-sectional view schematically showing an example of a sealing material according to the present invention. FIG. 2 is a cross-sectional view schematically showing another example of a sealing material according to the present invention. FIG. 3 is a cross-sectional view schematically showing yet another example of a sealing material according to the present invention. FIG. 4 is a cross-sectional view schematically showing an example of a sealing structure according to the present invention. FIG. 5 is a cross-sectional view schematically showing another example of a sealing structure according to the present invention. FIG. 6 is a cross-sectional view schematically showing yet another example of a sealing structure according to the present invention. FIG. 7 is an optical microscope photograph of a sample according to Example 1. FIG. 8 is an optical microscope photograph of a sample according to Comparative Example 2. FIG. 9 is an optical microscope photograph of a sample according to Comparative Example 4.

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. However, the present invention is not limited to the following embodiments.

[0012] Fig. 1 is a cross-sectional view schematically showing an example of a sealing material according to the present invention. As shown in Fig. 1, the sealing material 1a includes a foam 10. The foam 10 contains an olefin resin and a thermoplastic elastomer. The sealing material 1a includes a first region 11 having a thickness of 50 µm and including the surface of the sealing material 1a. The first region 11 has a tensile modulus E of 0.35 to 230 MPa. 11 The tensile modulus E 11 can be determined, for example, according to the method described in the Examples. A kneaded mixture of 5% by mass of the foam 10 and 95% by mass of polypropylene (virgin PP) is molded into a sheet-like sample having a thickness of 200 μm. 2 The ratio R of the area occupied by the heterogeneous portions to the total area of ​​the sample is 10% or less. In this sample, the heterogeneous portions form a dispersed phase. The polypropylene used to prepare this sample may be a commercially available polypropylene used for extrusion molding, for example, Prime Polypro E701G manufactured by Prime Polymer Co., Ltd. The kneaded material is obtained, for example, by uniformly kneading 5% by mass of foam 10 and 95% by mass of polypropylene while heating. The heterogeneous portions are surrounded by a continuous phase in the sample. The heterogeneous portions can be optically distinguishable, for example. For example, when observing this sample with an optical microscope, the portions where the heterogeneous portions are present and the portions where the heterogeneous portions are not present may have different hues, brightnesses, or saturations. Therefore, the portions where the heterogeneous portions are present can be distinguished from the other portions, for example, by observing the sample with an optical microscope. The heterogeneous portions may also be distinguishable by methods other than optical methods. The portions where the heterogeneous portions are present can be identified, for example, as portions having a maximum diameter of 10 μm or more. For example, in an image of the sample observed under an optical microscope, a heterogeneous portion having a maximum diameter of 10 μm or more is identified, which shows a contour relative to the homogeneous phase of virgin PP due to differences in hue, saturation, or brightness. This contour can be recognized, for example, by the coloring or opacity of the heterogeneous portion relative to the homogeneous phase of virgin PP. For example, by drawing a line around the contour where the heterogeneous portion exists and calculating the area of ​​the portion surrounded by the line, it is possible to determine the area of ​​1 cm in a plan view of the sample. 2The ratio of the area occupied by the heterogeneous portion forming the dispersed phase to the area of ​​the particle can be calculated.

[0013] In the above sample, when the ratio R is 10% or less, the material obtained by recycling the sealing material 1a tends to have the desired mechanical strength, and the sealing material 1a is easy to recycle. In particular, the sealing material 1a is advantageous from the viewpoint of material recycling.

[0014] The ratio R is preferably 8% or less, more preferably 5% or less, even more preferably 3% or less, and particularly preferably 1% or less. The ratio R may be 0%.

[0015] Tensile modulus E of first portion 11 11 When the first portion 11 of the sealing material 1a is brought into contact with another member to seal between the sealing material 1a and the other member, the contact area between the sealing material 1a and the other member is likely to be large due to the fact that the sealing material 1a is likely to exhibit high water stopping properties.

[0016] Tensile modulus E 11 is preferably 220 MPa or less, more preferably 210 MPa or less, even more preferably 200 MPa or less, and particularly preferably 180 MPa or less.

[0017] If the surfaces of the sealing material tend to stick together or to other components, the sealing material becomes difficult to handle during installation. 11 When the pressure is 0.35 MPa or more, the sealing material 1a is less likely to stick to itself during the installation work, making it easy to handle.

[0018] Tensile modulus E 11 is preferably 0.5 MPa or more, more preferably 0.8 MPa or more, even more preferably 1 MPa or more, and particularly preferably 1.5 MPa or more.

[0019] Tensile modulus E 11From the viewpoint of water-stopping properties and ease of installation of the sealing material 1a, the pressure is preferably 0.5 to 220 MPa, more preferably 0.5 to 210 MPa, even more preferably 0.5 to 200 MPa, and particularly preferably 1 to 200 MPa.

[0020] The content of the olefin resin in the foam 10 is not limited to a specific value. The content of the olefin resin in the foam 10 is, for example, 10% to 40% by mass. When this content is 10% by mass or more, it is easy to obtain a foam 10 that has been foamed in a desired state, and for example, it is easy to reduce the apparent density of the foam 10. When this content is 40% by mass or less, it is easy to reduce the flexural modulus of the foam 10, and it is easy to attach the foam 10 along a curved surface.

[0021] The olefin resin contained in the foam 10 is not limited to a specific type of olefin resin. For example, the olefin resin may include at least one selected from the group consisting of polyethylene (PE) and polypropylene (PP). This makes the foam 10 easier to recycle.

[0022] The PE is not limited to a specific PE, and may be, for example, low-density polyethylene (LDPE), high-density polyethylene (HDPE), or linear low-density polyethylene (LLDPE).

[0023] The PP is not limited to a specific type. The PP may be a homopolymer, a random polymer, or a block copolymer. The PP may be, for example, high melt tension polypropylene (HMS-PP). In this case, it is easier to obtain a foam 10 that is foamed in the desired state. An example of a high melt tension polypropylene is Waymax (registered trademark) provided by Japan Polypropylene Corporation.

[0024] The content of the thermoplastic elastomer contained in the foam 10 is not limited to a specific value. The content of the thermoplastic elastomer in the foam 10 is, for example, 50% to 90% by mass. When the content of the thermoplastic elastomer is 50% by mass or more, the flexural modulus of the foam 10 tends to be low, and the foam 10 can be easily attached along a curved surface. When the content of the thermoplastic elastomer is 90% by mass or less, the foam 10 is easily foamed in the desired state, and, for example, the apparent density of the foam 10 tends to be low.

[0025] The thermoplastic elastomer is not limited to a specific thermoplastic elastomer, and examples of the thermoplastic elastomer include styrene block copolymers (SBC), thermoplastic polyolefins (TPO), thermoplastic polyurethanes (TPU), polyester-based thermoplastic elastomers (TPC), polyamide block copolymers (TPA), and dynamically crosslinked thermoplastic elastomers (TPV).

[0026] The thermoplastic elastomer includes, for example, ethylene propylene rubber (EPDM). The inclusion of such a thermoplastic elastomer tends to lower the flexural modulus of the foam 10, making it easier to foam in the desired state. An example of such a thermoplastic elastomer is TPV.

[0027] The foam 10 may contain, for example, ethylene-vinyl acetate copolymer (EVA). This tends to lower the flexural modulus of the foam 10. The EVA is not limited to a specific EVA, and for example, the vinyl acetate (VA) content in the EVA is not limited to a specific value. The VA content in the EVA is, for example, 5% to 50% by mass, and may also be 5% to 40% by mass, 10% to 40% by mass, 15% to 40% by mass, or 20% to 40% by mass. The EVA may be included as a thermoplastic elastomer.

[0028] The foam 10 may contain additive components other than the polyolefin resin and the thermoplastic elastomer, as needed. Examples of the additive components include colorants, flame retardants, and various fillers. An example of a colorant is carbon black. Examples of flame retardants are hydroxides such as calcium hydroxide, magnesium hydroxide, and aluminum hydroxide.

[0029] The apparent density of the foam 10 is not limited to a specific value. The apparent density is, for example, 0.15 g / cm 3 and preferably less than 0.14 g / cm 3 More preferably, it is 0.12 g / cm or less. 3 or less, and more preferably 0.10 g / cm 3 For example, 0.01 g / cm 3 That's all.

[0030] The shape of the sealing material 1a is not limited to a specific shape. As shown in FIG. 1, the sealing material 1a has a thickness t 1a Since the foam 10 contains an olefin resin, it has a thickness t of 0.5 mm or more. 1a Therefore, the foam 10 can be used by being disposed between parts where a relatively large clearance exists.

[0031] The sealing material 1a has a thickness t of 0.5 mm or more. 1a In this case, the first region 11 forms at least one of both ends of the sealing material 1a in the thickness direction. The sealing material 1a may include a pair of first regions 11 arranged at both ends of the sealing material 1a in the thickness direction.

[0032] The thickness t may be 1 mm or more, 2 mm or more, 3 mm or more, 5 mm or more, or 10 mm or more, and is, for example, 50 mm or less.

[0033] The sealing material 1a may be in the form of a sheet or a strip, or may be in the form of a roll.

[0034] The foam 10 can be produced, for example, by foam molding a resin composition containing an olefin resin and a thermoplastic elastomer. The foam molding may be based on physical foaming or chemical foaming. For physical foaming, carbon dioxide gas or nitrogen gas is used, for example. The foaming agent used for chemical foaming may be an organic foaming agent or an inorganic foaming agent.

[0035] Examples of organic blowing agents include azo blowing agents, N-nitroso blowing agents, hydrazide blowing agents, semicarbazide blowing agents, fluorinated alkane blowing agents, triazole blowing agents, and other known organic blowing agents. Examples of azo blowing agents include azodicarboxylic acid amide (ADCA), barium azodicarboxylate, azobisisobutyronitrile (AIBN), azocyclohexylnitrile, and azodiaminobenzene. Examples of N-nitroso blowing agents include N,N'-dinitrosopentamethylenetetramine (DTP), N,N'-dimethyl-N,N'-dinitrosoterephthalamide, and trinitrosotrimethyltriamine. Examples of hydrazide-based blowing agents include 4,4'-oxybis(benzenesulfonylhydrazide) (OBSH), paratoluenesulfonylhydrazide, diphenylsulfone-3,3'-disulfonylhydrazide, 2,4-toluenedisulfonylhydrazide, p,p-bis(benzenesulfonylhydrazide) ether, and benzene-1,3-disulfonylhydrazide, allylbis(sulfonylhydrazide). Examples of semicarbazide-based blowing agents include p-toluenesulfonylsemicarbazide and 4,4'-oxybis(benzenesulfonylsemicarbazide). Examples of fluorinated alkane-based blowing agents include trichloromonofluoromethane and dichloromonofluoromethane. An example of a triazole-based blowing agent is 5-morpholyl-1,2,3,4-thiatriazole. The organic blowing agent may be thermally expandable microparticles in which a thermally expandable substance is encapsulated in microcapsules. Examples of such thermally expandable fine particles include commercially available products such as Microsphere (trade name, manufactured by Matsumoto Yushi Co., Ltd.).

[0036] Examples of inorganic foaming agents include bicarbonates, carbonates, nitrites, borohydrides, inorganic azides, and other known inorganic foaming agents. Examples of bicarbonates include sodium bicarbonate and ammonium bicarbonate. Examples of carbonates include sodium carbonate and ammonium carbonate. Examples of nitrites include sodium nitrite and ammonium nitrite. Examples of borohydrides include sodium borohydride. These foaming agents may be used alone or in combination of two or more.

[0037] In chemical foaming, a predetermined amount of a foaming agent is mixed with the resin composition. The amount of the foaming agent is, for example, 0.1 parts by mass or more, preferably 1 part by mass or more, and more preferably 10 parts by mass or more, per 100 parts by mass of the resin composition. The amount of the foaming agent is, for example, 50 parts by mass or less, preferably 30 parts by mass or less.

[0038] In chemical foaming, a foaming assistant is added as needed. Examples of the foaming assistant include urea-based foaming assistants, salicylic acid-based foaming assistants, benzoic acid-based foaming assistants, and metal oxides such as zinc oxide. The foaming assistants are preferably urea-based foaming assistants and metal oxides. These foaming assistants may be used alone or in combination of two or more.

[0039] The blending ratio of the foaming aid is, for example, 0.5 parts by mass or more, and preferably 1 part by mass or more, relative to 100 parts by mass of the resin composition, and, for example, 20 parts by mass or less, and more preferably 10 parts by mass or less, relative to 100 parts by mass of the resin composition.

[0040] For example, the resin composition is not subjected to a crosslinking treatment such as electron beam irradiation in the production of the foam 10. This makes it easier to obtain a foam 10 with a ratio R of 10% or less, which is advantageous from the viewpoint of recycling.

[0041] As shown in FIG. 1 , the first portion 11 may be formed, for example, only by the foam 10. In this case, the structure of the sealing material 1a is likely to be simple. The sealing material 1a may be formed only by the foam 10. In this case, the tensile modulus E 11 may be, for example, 50 MPa to 230 MPa.

[0042] The sealing material 1a can be modified from various viewpoints, for example. The sealing material 1a can be modified, for example, to a sealing material 1b shown in FIG. 2 and a sealing material 1c shown in FIG. 3. The sealing materials 1b and 1c are configured in the same manner as the sealing material 1a, except for portions that are particularly described. The components of the sealing materials 1b and 1c that are the same as or correspond to the components of the sealing material 1a are given the same reference numerals, and detailed description thereof will be omitted. The description of the sealing material 1a also applies to the sealing materials 1b and 1c, unless technically inconsistent.

[0043] As shown in Figures 2 and 3, the sealing materials 1b and 1c each include a surface layer 20. The surface layer 20 includes at least a part of the first portion 11. The surface layer 20 includes one side of the sealing material 1b. In the sealing material 1c, the pair of surface layers 20 includes both sides of the sealing material 1c. In this way, the surface layer 20 includes at least one side of the sealing member. With this configuration, since the first portion 11 includes the surface layer 20, the tensile modulus E 11 The tensile modulus E can be adjusted to a range that is difficult to adjust using only the foam 10. 11 For example, in the sealing materials 1b and 1c, the tensile modulus E 11 may be, for example, 0.35 MPa to 50 MPa.

[0044] The thickness of the surface layer 20 is not limited to a specific value as long as the surface layer 20 includes at least a part of the first portion 11. The thickness of the surface layer 20 is, for example, 10 to 1000 μm. In this case, the tensile modulus E 11 However, it is easier to adjust the thickness to a desired range that is difficult to adjust using only the foam 10. The surface layer 20 may form only a part of the first region 11, or may form the entire first region 11. A part of the surface layer 20 may form the entire first region 11.

[0045] The surface layer 20 contains, for example, an olefin-based resin. In this case, the above sample is less likely to have heterogeneous portions due to the surface layer 20, and it is easy to avoid an increase in the ratio R due to the surface layer 20. Examples of the olefin-based resin contained in the surface layer 20 are EVA resin, α-olefin resin, and olefin-based thermoplastic elastomer. The olefin-based thermoplastic elastomer may contain EPDM.

[0046] The surface layer 20 is, for example, a layer denser than the foam 10 and has a lower tensile modulus of elasticity than the foam 10. In this case, when the surface layer 20 is brought into contact with another member to seal between the sealing material 1b or 1c and the other member, the contact area between the sealing material 1b or 1c and the other member tends to be larger, and therefore the sealing material 1b or 1c tends to exhibit higher water-stopping properties.

[0047] The surface layer 20 may have adhesiveness at room temperature (20° C.±15° C.), for example. In this case, even if the compressibility of the sealing material 1b or 1c is relatively low, the contact area between the sealing material 1b or 1c and other members tends to be large, and the sealing material 1b or 1c tends to exhibit high water-stopping properties.

[0048] A seal structure can be provided using the above-described seal member. Fig. 4 is a cross-sectional view showing a typical example of the seal structure. As shown in Fig. 4, in a seal structure 2a, a seal material 1a is disposed between a first member 3 and a second member 4, and seals between the first member 3 and the second member 4. As described above, the tensile modulus E 11 Since the compressive strength is 230 MPa or less, the seal structure 2a is likely to have high water-stopping properties.

[0049] In the seal structure 2a, for example, the foam 10 is in contact with the first member 3. The compressive strain of the seal material 1a in the seal structure 2a is not limited to a specific value. The compressive strain is, for example, 90 to 95%. This makes it easier for the seal structure 2a to have high water-stopping properties. In the seal structure 2a, the foam 10 is in contact with the second member 4, for example.

[0050] 5 is a cross-sectional view showing a schematic diagram of another example of a sealing structure. As shown in FIG. 5, in a sealing structure 2b, a sealing material 1b is disposed between a first member 3 and a second member 4, and seals between the first member 3 and the second member 4. As described above, the tensile modulus E 11 Since the compressive strength is 230 MPa or less, the seal structure 2b is likely to have high water-stopping properties.

[0051] In the seal structure 2b, for example, the surface layer 20 is in contact with the first member 3. The compressive strain of the seal material 1b in the seal structure 2b is not limited to a specific value. The compressive strain is, for example, 5 to 10%. This makes it easier for the load applied to the first member 3 in the seal structure 2b to be reduced.

[0052] 6 is a cross-sectional view showing a schematic diagram of another example of a seal structure. As shown in FIG. 6, in a seal structure 2c, a seal material 1c is disposed between a first member 3 and a second member 4, and seals between the first member 3 and the second member 4. As described above, the tensile modulus E 11 Since the compressive strength is 230 MPa or less, the seal structure 2c is likely to have high water-stopping properties.

[0053] In the seal structure 2c, for example, the surface layer 20 is in contact with the first member 3 and the second member 4. The compressive strain of the seal material 1c in the seal structure 2c is not limited to a specific value. The compressive strain is, for example, 5 to 10% or less. This makes it easier for the load applied to the first member 3 in the seal structure 2c to be small.

[0054] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0055] Example 1: A resin composition according to Example 1 was obtained by mixing 20 parts by mass, 50 parts by mass, and 30 parts by mass of polypropylene (PP) Waymax MFX8 manufactured by Japan Polypropylene Corporation, thermoplastic elastomer Santoprene 201-67W171 manufactured by Celanese Corporation, and ethylene vinyl acetate copolymer (EVA) Evaflex EV250 manufactured by Mitsui DuPont Co., Ltd. Waymax MFX8 is a metallocene-based high melt tension polypropylene. Santoprene 201-67W171 is a TPV containing EPDM. The VA content of Evaflex EV250 was 28% by mass. The resin composition according to Example 1 was loaded into an extruder heated to 200°C. 120 g of CO2 gas was then injected into the extruder, and the die temperature was adjusted to 170°C. The resin composition according to Example 1 was extruded to obtain a foam according to Example 1. The foam according to Example 1 was used as the sealing material according to Example 1.

[0056] Example 2 A resin composition according to Example 2 was obtained by mixing 30 parts by mass, 50 parts by mass, and 20 parts by mass of the above-mentioned PP, the above-mentioned thermoplastic elastomer, and ethylene-vinyl acetate copolymer (EVA) Evaflex EV170 manufactured by DuPont-Mitsui Co., Ltd. The VA content in Evaflex EV170 was 33% by mass. A foam according to Example 2 was obtained in the same manner as in Example 1, except that the resin composition according to Example 2 was used instead of the resin composition according to Example 1. The foam according to Example 2 was used as the sealing material according to Example 2.

[0057] Example 3 The above-mentioned PP, the above-mentioned thermoplastic elastomer, and Evaflex EV250 were mixed in amounts of 30 parts by mass, 50 parts by mass, and 20 parts by mass, respectively, to obtain a resin composition according to Example 3. A foam according to Example 3 was obtained in the same manner as Example 1, except that the resin composition according to Example 3 was used instead of the resin composition according to Example 1. The foam according to Example 3 and resin sheet α were sandwiched between rolls heated to 170°C and subjected to thermal lamination, thereby obtaining a sealing material according to Example 3 in which the foam and resin sheet α were bonded together. The resin sheet α contained Evaflex EV40LX manufactured by DuPont-Mitsui Co., Ltd. and had a thickness of 200 μm.

[0058] Example 4 A sealing material according to Example 4 was obtained by laminating a foam and resin sheet β together in the same manner as in Example 3, except that resin sheet β was used instead of resin sheet α. Resin sheet β contained polyolefin elastomer Toughmer PN3560 manufactured by Mitsui Chemicals, Inc., and had a thickness of 200 μm.

[0059] Example 5: A thermal lamination process was performed in the same manner as in Example 3, except that resin sheet γ was used instead of resin sheet α, to obtain a sealing material according to Example 5 in which a foam and resin sheet γ were bonded together. Resin sheet γ contained Santoprene 201-67W171 and had a thickness of 200 μm.

[0060] Example 6 A sealing material according to Example 6 was obtained by laminating a foam and resin sheet 6 together in the same manner as in Example 3, except that resin sheet 6 was used instead of resin sheet α. Resin sheet δ contained polyolefin elastomer Toughmer PN20300 manufactured by Mitsui Chemicals, Inc., and had a thickness of 200 μm.

[0061] Comparative Example 1 A resin composition according to Comparative Example 1 was obtained by mixing 30 parts by mass, 50 parts by mass, and 20 parts by mass of polypropylene Waymax MFX8, Santoprene 201-67W171, and EVA Evaflex P1403 manufactured by DuPont-Mitsui Co., Ltd. The VA content in Evaflex P1403 was 14% by mass. A foam according to Comparative Example 1 was obtained in the same manner as in Example 1, except that the resin composition according to Comparative Example 1 was used instead of the resin composition according to Example 1. The foam according to Comparative Example 1 was used as the sealing material according to Comparative Example 1.

[0062] Comparative Example 2 EPT SEALER EE-1000 manufactured by Nitto Denko Corporation was used as a sealing material according to Comparative Example 2. EE-1000 is a foam containing EPDM.

[0063] <Comparative Example 3> A sealing material according to Comparative Example 3 was obtained by attaching Nitto Denko Corporation's double-sided adhesive tape No. 591 to the foam according to Example 3. This double-sided adhesive tape was a substrate-less double-sided adhesive tape made of an acrylic adhesive and had a thickness of 50 μm.

[0064] Comparative Example 4 Crosslinked polyolefin foam P·E-Lite (registered trademark) B-4 was used as the foam according to Comparative Example 4.

[0065] (Tensile Modulus) A 50 μm thick portion including the surface of the sealing material according to each Example and Comparative Examples 1 to 3 was cut out to prepare a test specimen for a tensile test. The test specimen was rectangular, measuring 5 mm wide and 70 mm long in plan view. A tensile test was performed on each test specimen using a dynamic viscoelasticity measuring device RSA-G2 manufactured by TA Instruments in tension mode. In this tensile test, the gauge length was 20 mm, the temperature was 25°C, and the frequency was 1.0 Hz. The tensile modulus was measured when a strain of 0.1% was applied. The results are shown in Tables 1 and 2.

[0066] (Thickness) The thickness of the foams according to each example and comparative example was measured using a 20φ dial gauge, Peacock Dial Thickness Gauge J-8, manufactured by Ozaki Seisakusho Co., Ltd. The results are shown in Tables 1 and 2.

[0067] (Water Stoppage) The sealing material according to each Example and Comparative Examples 1 to 3 was sandwiched between two aluminum plates, and the sealing material was compressed between the two aluminum plates so as to generate a predetermined compression strain. The thickness of each aluminum plate was 2 mm. The sealing material was sandwiched between the two aluminum plates so as to extend in a U-shape in plan view. 40 minutes after the sealing material was compressed between the two aluminum plates, water was added to a predetermined depth into the space surrounded by the two aluminum plates and the U-shaped sealing material. 24 hours after the addition of water, it was confirmed whether water leakage had occurred. The water stoppage of each sealing material was evaluated according to the following criteria. The results are shown in Tables 1 and 2. A: No water leakage at 10% compression strain and 70 mm water depth B: No water leakage at 90% compression strain and 90 mm water depth C: Water leakage at 90% compression strain and 90 mm water depth

[0068] (Handling Efficiency) The sealing materials according to each Example and Comparative Examples 1 to 3 were cut into squares with sides measuring 10 mm in plan view to prepare test specimens for evaluating handling ease. When a sheet or double-sided adhesive tape was placed on the surface of the sealing material in these test specimens, the same type of sheet or double-sided adhesive tape was attached to both sides of the foam. The test specimen was sandwiched between two stainless steel SUS304 plates, and a 1 kg weight was placed on one of the plates for 1 minute. One of the two plates had a hook. Next, a push-pull gauge manufactured by Imada was attached to the hook, and the force when the plate was pulled at a speed of 10 mm / sec was measured. The results are shown in Tables 1 and 2. The smaller this force, the less likely the sealing material was to stick, indicating better handling ease. Handling ease was evaluated according to the following criteria: Good: Less than 4.5 N; Not enough: 4.5 N or more.

[0069] (Observation by Optical Microscope) Using a Lapolast Mill manufactured by Toyo Seiki Seisakusho, the sealing materials according to each Example and Comparative Examples 1 to 3 and the foam according to Comparative Example 4 were kneaded with Prime Polypro E701G polypropylene (PP) manufactured by Prime Polymer Co., Ltd. at 190°C for 10 minutes at a rotation speed of 10 rotations per minute (rpm). The content of components derived from the sealing material or foam in the kneaded mixture was 5% by mass, and the content of Prime Polypro E701G in the kneaded mixture was 95% by mass. The kneaded mixture was molded into a sheet having a thickness of 200 μm by heat pressing to obtain a sample for observation by optical microscope. One main surface of the obtained sample was observed at 20x magnification using a Keyence VHX-7000 microscope to obtain an observation image. Optical microscope photographs of the samples derived from the sealing materials according to Example 1 and Comparative Example 2 and the foam according to Comparative Example 4 are shown in Figures 7, 8, and 9, respectively.

[0070] In the obtained observation image, the area where the heterogeneous portion existed was surrounded by a line along the outline of the heterogeneous portion having a maximum diameter of 10 μm or more, which was outlined by differences in hue, saturation, or brightness from the uniform phase of virgin PP, and the area of ​​the portion surrounded by the line was calculated. 2 The ratio of the area occupied by the heterogeneous portion forming the dispersed phase to the area of ​​the sample was calculated. The results are shown in Tables 1 and 2.

[0071] (Recycling Evaluation) Using a Lapolast Mill manufactured by Toyo Seiki Seisakusho, the sealing materials according to each Example and Comparative Examples 1 to 3, and the foam according to Comparative Example 4 were kneaded with Prime Polypro E701G at 190°C for 10 minutes at a rotation speed of 10 rotations per minute (rpm). The content of components derived from the sealing material or foam in the kneaded mixture was 5% by mass, and the remainder of the kneaded mixture was virgin polypropylene. A sheet having a thickness of 200 μm was obtained by hot pressing the kneaded mixture. The obtained sheet was cut into a width of 10 mm to obtain a test piece for tensile testing. A tensile test was performed on the obtained test piece using a tensile tester to measure its breaking strength. In this tensile test, the distance between chucks was set to 40 mm, and the pulling speed was set to 500 mm / min. The test temperature was adjusted to 23°C ± 2°C. A tensile test was performed under the same conditions on a test piece according to the Reference Example made only of virgin polypropylene, and its breaking strength was measured. The rate of decrease in breaking strength for each example and comparative example was determined based on the following formula (1): A is the breaking strength of the test piece according to the reference example, BS B is the breaking strength of the test piece obtained from the kneaded material containing the component derived from the foam. Breaking strength reduction rate [%] = {(BS A -BS B ) / BS A}×100 Formula (1)

[0072] Each foam was evaluated for recyclability according to the following criteria based on the percentage decrease in breaking strength. The results are shown in Tables 1 and 2. Good: The percentage decrease in breaking strength was less than 10%. Not enough: The percentage decrease in breaking strength was 10% or more.

[0073] As shown in Tables 1 and 2, in each Example, the rate of decrease in breaking strength was less than 10%, and a positive evaluation was given for recyclability. In other words, the foams according to each Example are understood to be advantageous from the viewpoint of recycling. In each Example, the proportion of the area occupied by the portion where the heterogeneous portion is present is 10% or less, which is thought to contribute to the low rate of decrease in breaking strength. For example, in Comparative Examples 2 and 4, the proportion of the area occupied by the portion where the heterogeneous portion is present is greater than 10%, and a positive evaluation was not given for recyclability.

[0074] As shown in Table 1, the water stopping ability of the sealing material according to each example was evaluated as "A" or "B." On the other hand, as shown in Table 2, the water stopping ability of the sealing material according to Comparative Example 1 was evaluated as "C." Comparing each example with Comparative Example 1, it can be seen that the sealing material is more likely to exhibit the desired water stopping ability when the tensile modulus of elasticity at a 50 μm thickness portion including the surface of the sealing material is 230 MPa or less.

[0075] As shown in Table 1, the handleability of the sealing material according to each example was evaluated as "Good." On the other hand, the handleability of the sealing material according to Comparative Example 3 was evaluated as "Not enough." Comparing each example with Comparative Example 3, it can be seen that the sealing material has the desired handleability and is easy to install, because the tensile modulus of elasticity at a 50 μm thickness including the surface of the sealing material is 0.35 MPa or more.

[0076]

[0077]

[0078] A first aspect of the present invention is a sealing material comprising a foam containing an olefin resin and a thermoplastic elastomer, the sealing material including a first portion having a thickness of 50 μm including a surface of the sealing material, the first portion having a tensile modulus of 0.35 to 230 MPa, and a sheet-like sample obtained by molding a mixture of 5 mass % of the sealing material and 95 mass % of polypropylene to a thickness of 200 μm, the sheet-like sample having a thickness of 1 cm in a plan view. 2The ratio of the area occupied by the heterogeneous portion forming the dispersed phase to the total area of ​​the sealing material is 10% or less.

[0079] A second aspect of the present invention provides the sealing material according to the first aspect, wherein the content of the olefin resin in the foam is 10% by mass to 40% by mass.

[0080] A third aspect of the present invention provides the sealing material according to the first or second aspect, wherein the olefin resin includes at least one selected from the group consisting of polyethylene and polypropylene.

[0081] A fourth aspect of the present invention provides the sealing material according to any one of the first to third aspects, wherein the content of the thermoplastic elastomer in the foam is 50% by mass to 90% by mass.

[0082] A fifth aspect of the present invention provides the sealing material according to any one of the first to fourth aspects, wherein the thermoplastic elastomer includes ethylene propylene rubber (EPDM).

[0083] A sixth aspect of the present invention provides the sealing material according to any one of the first to fifth aspects, wherein the foam contains an ethylene vinyl acetate copolymer.

[0084] A seventh aspect of the present invention provides a sealing material having a thickness of 0.5 mm or more in any one of the first to sixth aspects.

[0085] An eighth aspect of the present invention provides a sealing material according to any one of the first to seventh aspects, comprising a surface layer including at least a portion of the first region and including at least one surface of the sealing material.

[0086] A ninth aspect of the present invention provides the sealing material according to the eighth aspect, wherein the surface layer contains an olefin-based resin.

Claims

1. A sealing material comprising a foam containing an olefin resin and a thermoplastic elastomer, the sealing material including a first portion having a thickness of 50 μm including a surface of the sealing material, the first portion having a tensile modulus of 0.35 to 230 MPa, and a sheet-like sample obtained by molding a mixture of 5 mass % of the sealing material and 95 mass % of polypropylene to a thickness of 200 μm, the sheet-like sample having a thickness of 1 cm in a plan view. 2 A sealing material, wherein the proportion of the area occupied by the heterogeneous portion forming the dispersed phase in the area of the sealing material is 10% or less.

2. The sealing material according to claim 1, wherein the content of the olefin resin in the foam is 10% by mass to 40% by mass.

3. The sealing material according to claim 1, wherein the olefin resin includes at least one selected from the group consisting of polyethylene and polypropylene.

4. The sealing material according to claim 1, wherein the content of the thermoplastic elastomer in the foam is 50% by mass to 90% by mass.

5. The sealing material according to claim 1, wherein the thermoplastic elastomer includes ethylene propylene rubber (EPDM).

6. The sealant according to claim 1, wherein the foam comprises ethylene vinyl acetate copolymer.

7. The sealing material according to claim 1, having a thickness of 0.5 mm or more.

8. The sealing material according to claim 1, further comprising a surface layer including at least a portion of the first portion and including at least one surface of the sealing material.

9. The sealing material according to claim 8, wherein the surface layer contains an olefin-based resin.

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