Foam and member

Abstract

A foam 1a contains: a first component constituted of an olefin resin; and a second component. The second component contains at least one polymer selected from the group consisting of thermoplastic elastomers and ethylene-vinyl acetate copolymers (EVAs). A sheet-shaped sample is obtained by molding, to a thickness of 200 μm, a kneaded product of 5 mass% of the foam 1a and 95 mass% of polypropylene. The percentage of the area occupied by the portion of the sample where a heterogeneous part thereof forming a dispersed phase is present is 10% or less in a 1 cm2 surface area of the sample in a plan view. The foam 1a has a flexural modulus of 4.5 MPa or less.

Description

Foams and components

[0001] The present invention relates to a foam and a component.

[0002] BACKGROUND ART Foams containing olefin resins have been known in the past.

[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 The polyolefin resin composition has a gel fraction of 25 to 60% by mass. The polyolefin resin composition is irradiated with an electron beam under predetermined conditions to be crosslinked.

[0004] Patent Document 2 describes a polyolefin resin foam sheet, which has a flexural modulus of 150 kPa or less and a shrinkage rate of 5% or less in the in-plane direction when cured for 1 hour at a temperature of 120° C. 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 be crosslinked.

[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 it is believed that the crosslinked material exists in the polyolefin resin foam sheet. This is not advantageous from the viewpoint of recycling the foam. In addition, it may be important that the foam can be easily attached to a curved surface.

[0007] Therefore, the present invention provides a foam that is advantageous from the viewpoints of ease of recycling and ease of attachment along curved surfaces.

[0008] The present invention provides a foam comprising a first component which is an olefin resin and a second component which contains at least one selected from the group consisting of a thermoplastic elastomer and an ethylene-vinyl acetate copolymer, wherein a kneaded mixture of 5% by mass of the foam and 95% by mass of polypropylene is molded into a sheet-like sample having a thickness of 200 μm, and the sheet-like sample has a thickness of 1 cm in a plan view. 2 a ratio of an area occupied by a portion where a heterogeneous portion forming a dispersed phase is present to an area of ​​the foam of 10% or less, and the foam has a flexural modulus of elasticity of 4.5 MPa or less.

[0009] The present invention also provides a member comprising: the foam; and a pressure-sensitive adhesive layer covering at least one surface of the foam.

[0010] The foamed material is advantageous in terms of ease of recycling and ease of attachment to curved surfaces.

[0011] Fig. 1 is a cross-sectional view schematically showing one example of a foam according to the present invention. Fig. 2 is a cross-sectional view schematically showing another example of a foam according to the present invention. Fig. 3 is a cross-sectional view schematically showing yet another example of a foam according to the present invention. Fig. 4 is an optical microscope photograph of a sample according to Example 1. Fig. 5 is an optical microscope photograph of a sample according to Comparative Example 3. Fig. 6 is an optical microscope photograph of a sample according to Comparative Example 4.

[0012] 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.

[0013] FIG. 1 is a cross-sectional view schematically illustrating an example of a foam according to the present invention. The foam 1a contains a first component, which is an olefin resin, and a second component. The second component contains at least one selected from the group consisting of a thermoplastic elastomer and an ethylene vinyl acetate copolymer (EVA). A kneaded mixture of 5% by mass of the foam 1a and 95% by mass of polypropylene (virgin PP) is molded to a thickness of 200 μm to obtain a sheet-like sample. The 1 cm plan view of this sample shows a thickness of 200 μm. 2The ratio R of the area occupied by the heterogeneous portion to the total area of ​​the sample is 10% or less. In this sample, the heterogeneous portion forms 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 1a and 95% by mass of polypropylene while heating. The heterogeneous portion is surrounded by a continuous phase in the sample. The heterogeneous portion can be optically distinguishable, for example. For example, when observing this sample with an optical microscope, the portion where the heterogeneous portion is present and the portion where the heterogeneous portion is not present may have different hues, brightness, or saturations. Therefore, the portion where the heterogeneous portion is present can be distinguished from the other portions by observing the sample with an optical microscope, for example. The heterogeneous portion may also be distinguishable by methods other than optical methods. The foam 1a has a flexural modulus of 4.5 MPa or less. The flexural modulus of the foam 1a can be determined, for example, according to the method described in the Examples with reference to Japanese Industrial Standards (JIS) K7074 or ASTM D790. The portion where the heterogeneous portion exists can be identified, for example, as a portion 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 an outline relative to the homogeneous phase of virgin PP due to differences in hue, saturation, or brightness. This outline 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 portion where the heterogeneous portion exists along the outline and calculating the area of ​​the portion surrounded by the line, the area of ​​1 cm of the sample in plan view can be determined. 2 The ratio of the area occupied by the heterogeneous portion forming the dispersed phase to the area of ​​the particle can be calculated.

[0014] In the above sample, when the ratio R is 10% or less, the material obtained by recycling the foam 1a tends to have the desired mechanical strength, and the foam 1a is easy to recycle. In particular, the foam 1a is advantageous from the viewpoint of material recycling.

[0015] 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%.

[0016] As described above, the foam 1a has a flexural modulus of 4.5 MPa or less. This makes it easy to attach the foam 1a along a curved surface. Olefin resin foams have high bulk strength and tend to be rigid. In particular, crosslinking of olefin resin foams increases foamability but also tends to increase rigidity. On the other hand, since the foam 1a contains the second component, the flexural modulus tends to be low.

[0017] The flexural modulus of the foam 1a is preferably 4.2 MPa or less, more preferably 4 MPa or less, even more preferably 3 MPa or less, and particularly preferably 2.5 MPa or less. The flexural modulus of the foam 1a is, for example, 0.1 MPa or more.

[0018] The content of the olefin resin, which is the first component of the foam 1a, is not limited to a specific value, as long as the proportion R is 10% or less and the foam 1a has a flexural modulus of 4.5 MPa or less. The olefin resin content in the foam 1a is, for example, 10% to 40% by mass. When this content is 10% by mass or more, the foam 1a is easily foamed in the desired state, and, for example, the apparent density of the foam 1a is easily reduced. When this content is 40% by mass or less, the flexural modulus of the foam 1a is easily reduced, and the foam 1a can be easily attached to a curved surface.

[0019] The olefin resin contained in the foam 1a is not limited to a specific type of olefin resin, and may include, for example, at least one selected from the group consisting of polyethylene (PE) and polypropylene (PP), making the foam 1a easier to recycle.

[0020] 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).

[0021] The PP is not limited to a specific PP. 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 1a that is foamed in the desired state. An example of a high melt tension polypropylene is Waymax (registered trademark) provided by Japan Polypropylene Corporation.

[0022] The content of the second component in the foam 1a is not limited to a specific value, as long as the ratio R is 10% or less and the foam 1a has a flexural modulus of 4.5 MPa or less. The content of the second component in the foam 1a is, for example, 50% to 90% by mass. When the content of the second component is 50% by mass or more, the flexural modulus of the foam 1a tends to be low, making it easier to attach the foam 1a along a curved surface. When the content of the second component is 50% by mass or less, it is easier to obtain a foam 1a that has been foamed in a desired state, and for example, the apparent density of the foam 1a tends to be low.

[0023] 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).

[0024] The second component includes a thermoplastic elastomer, such as ethylene propylene rubber (EPDM). The inclusion of such a thermoplastic elastomer tends to lower the flexural modulus of the foam 1a, making it easier to achieve foaming in a desired state. An example of such a thermoplastic elastomer is TPV.

[0025] As described above, the second component may contain EVA. This tends to reduce the flexural modulus of the foam 1a. 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 be 5% to 40% by mass.

[0026] The foam 1a may contain additional components other than the first and second components as needed. Examples of the additional 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.

[0027] The apparent density of the foam 1a 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.

[0028] The shape of the foam 1a is not limited to a specific shape. As shown in Fig. 1, the foam 1a has a thickness t of, for example, 3 mm or more. Because the foam 1a contains an olefin resin, it is easy to foam-mold it to have a thickness t of 3 mm or more. Therefore, the foam 1a can be used by being disposed between parts that have a relatively large clearance.

[0029] The thickness t may be 5 mm or more, 10 mm or more, or may be, for example, 50 mm or less.

[0030] The 50% compressive load of the foam 1a is not limited to a specific value. The 50% compressive load is the compressive load when a 50% strain is generated in the thickness direction of the foam 1a, and can be measured, for example, according to the method described in the Examples. The 50% compressive load of the foam 1a is, for example, 5.0 N / cm 2In this case, when the foam 1a is placed in a compressed state, the load applied to the article in contact with the foam 1a tends to be small. The 50% compression load is, for example, 0.2 N / cm 2 As a result, when the foam 1a is placed in a compressed state, the strength of attachment between the foam 1a and an article that comes into contact with the foam 1a tends to be high.

[0031] The foam 1a may be in the form of a sheet or a strip, or may be in the form of a roll.

[0032] The foam 1a can be produced, for example, by foam molding a resin composition containing the first component and the second component. The foam molding may be based on physical foaming or chemical foaming. For physical foaming, for example, carbon dioxide gas or nitrogen gas is used. The foaming agent used for chemical foaming may be an organic foaming agent or an inorganic foaming agent.

[0033] 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.).

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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.

[0038] For example, in the production of the foam 1a, the resin composition is not subjected to a crosslinking treatment such as electron beam irradiation, which makes it easier to obtain a foam 1a with a ratio R of 10% or less, which is advantageous from the viewpoint of recycling.

[0039] The foam 1a may be used alone. As shown in Figures 2 and 3, a member may be provided that includes the foam 1a and a pressure-sensitive adhesive layer 20 covering at least one side of the foam 1a. This allows the member including the foam 1a to be attached to a predetermined article by pressing the pressure-sensitive adhesive layer 20 against the predetermined article. For example, in the member 2a shown in Figure 2, the pressure-sensitive adhesive layer 20 is arranged to cover only one side of the foam 1a. In the member 2b shown in Figure 3, the pressure-sensitive adhesive layer 20 is arranged to cover both sides of the foam 1a. In other words, in the member 2b, a pair of pressure-sensitive adhesive layers 20 are arranged along a pair of parallel surfaces of the foam 1a.

[0040] The adhesive layer 20 is not limited to a specific adhesive layer. The adhesive forming the adhesive layer may be, for example, an acrylic adhesive, a urethane adhesive, or a rubber adhesive. The thickness of the adhesive layer 20 is, for example, 5 to 400 μm, and may be 10 to 300 μm or 50 to 250 μm.

[0041] 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.

[0042] Example 1: A resin composition according to Example 1 was obtained by mixing 30 parts by mass of polypropylene (PP) Waymax MFX8 manufactured by Japan Polypropylene Corporation, 50 parts by mass of thermoplastic elastomer Santoprene 201-67W171 manufactured by Celanese Corporation, and 20 parts by mass of ethylene vinyl acetate copolymer (EVA) Evaflex EV250 manufactured by DuPont-Mitsui 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.

[0043] Examples 2 to 4 Resin compositions according to Examples 2, 3, and 4 were obtained in the same manner as in Example 1, except that the amounts of the PP, the thermoplastic elastomer, and the EVA were changed as shown in Table 1. Foams according to Examples 2, 3, and 4 were obtained in the same manner as in Example 1, except that the resin compositions according to Examples 2, 3, and 4 were used instead of the resin composition according to Example 1.

[0044] Example 5 Polypropylene Waymax MFX8 and Evaflex EV250 were mixed in amounts of 30 parts by mass and 70 parts by mass, respectively, to obtain a resin composition according to Example 5. A foam according to Example 5 was obtained in the same manner as in Example 1, except that the resin composition according to Example 5 was used instead of the resin composition according to Example 1.

[0045] Examples 6 to 9 and Comparative Example 1 Polypropylene Waymax MFX8 and Santoprene 201-67W171 were mixed in the amounts shown in Table 1 or Table 2 to obtain resin compositions according to Examples 6 to 9 and Comparative Example 1. Foams according to Examples 6 to 9 and Comparative Example 1 were obtained in the same manner as in Example 1, except that the resin compositions according to Examples 6 to 9 and Comparative Example 1 were used instead of the resin composition according to Example 1.

[0046] Example 10 Polypropylene Waymax MFX8, Santoprene 201-67W171, Evaflex EV250, and polyethylene (PE) Excellen VL200 manufactured by Sumitomo Chemical Co., Ltd. were mixed in amounts of 20 parts by mass, 50 parts by mass, 20 parts by mass, and 10 parts by mass, respectively, to obtain a resin composition according to Example 10. A foam according to Example 10 was obtained in the same manner as in Example 1, except that the resin composition according to Example 10 was used instead of the resin composition according to Example 1.

[0047] Comparative Example 2 A foam according to Comparative Example 2 was obtained in the same manner as in Example 1, except that Santoprene 201-67W171 was used alone instead of the resin composition according to Example 1.

[0048] Comparative Example 3 As a foam according to Comparative Example 3, crosslinked polyolefin foam P·E-Lite (registered trademark) B-4 was used.

[0049] Comparative Example 4 As a foam according to Comparative Example 4, an EPDM foam EPTSEALER EE-1000 manufactured by Nitto Denko Corporation was used.

[0050] (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.

[0051] (Apparent Density) The apparent density of the foams of each Example and Comparative Example was measured using an MD-300S electronic hydrometer manufactured by Alpha Mirage. The results are shown in Tables 1 and 2. Based on the apparent density measurement results, the foamability was evaluated according to the following criteria: A: Apparent density of 0.07 g / cm 3B: Apparent density is 0.07 g / cm or less. 3 More than 0.15 g / cm 3 C: Apparent density is less than 0.15 g / cm 3 That's all.

[0052] (Observation by Optical Microscope) Using a Lapolastomill manufactured by Toyo Seiki Seisakusho Co., Ltd., the foams according to each Example and Comparative Example 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 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. The heat pressing was performed at 190°C for 60 seconds. 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 samples derived from the foams according to Example 1, Comparative Example 3, and Comparative Example 4 are shown in Figures 4, 5, and 6, respectively.

[0053] 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.

[0054] (Flexural Modulus) The foams of each Example and Comparative Example were cut into specimens with a thickness of 5 mm and a width of 10 mm to obtain specimens for measuring the flexural modulus. A three-point bending test was performed using an RSA-G2 manufactured by TA Instruments Japan in accordance with JIS K 7074 or ASTM D790 to obtain a load-deflection curve. In the three-point bending test, the support distance was 40 mm and the crosshead movement speed was 0.1 mm / sec. The flexural modulus Eb [MPa] of each foam was determined based on the following formula (A). The results are shown in Tables 1 and 2. In formula (A), L is the support distance, b is the width of the test specimen, h is the thickness of the test specimen, and (P / δ) is the gradient of the linear portion of the load-deflection curve, with the portion corresponding to a deflection of 0 to 0.5 mm being considered as the linear portion. Eb=(1 / 4)·(L 3 / bh 3 )・(P / δ) Formula (A)

[0055] (Recycling Evaluation) Using a Lapolast Mill manufactured by Toyo Seiki Seisakusho, the foams according to each Example and Comparative Example 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 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 heat pressing the kneaded mixture. The heat pressing was performed at 190°C for 60 seconds. 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 a 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 (B): 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 [%] = {(BSA -BS B ) / BS A}×100 Formula (B)

[0056] 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.

[0057] (Ease of Attachment to Curved Surfaces) The foams of each Example and Comparative Example were cut to a size of 10 mm wide and 6 mm thick to obtain evaluation samples. The evaluation samples were 70 mm long. Nitto Denko Corporation's No. 512 adhesive tape was placed between the evaluation sample and an ABS resin adherend to attach the evaluation sample to the adherend. The adherend had a cylindrical surface with a radius of 45 mm or 75 mm, and the evaluation sample was attached to the adherend so that the length direction of the evaluation sample coincided with the circumferential direction of the cylindrical surface. The evaluation samples were then left in an environment of 23°C for 3 days. The state of attachment of the evaluation sample to the adherend was visually confirmed, and the ease of attachment of each foam to a curved surface was evaluated according to the following criteria. The results are shown in Tables 1 and 2. A: No lifting or peeling of the evaluation sample was observed on the adherend including a cylindrical surface with a radius of 45 mm. B: No lifting or peeling of the evaluation sample was observed on the adherend including a cylindrical surface with a radius of 75 mm. C: Lifting or peeling of the evaluation sample is observed on an adherend including a cylindrical surface with a radius of 75 mm.

[0058] (50% Compression Load) The foams according to each Example and each Comparative Example were cut into squares with sides measuring 1 cm in plan view to obtain test specimens for compression tests. Using a Shimadzu Corporation AUTOGRAPH AGS-X 5kN universal testing machine, the test specimens were compressed at a test speed of 10 m / min to produce a 50% compression strain. This compressed state was maintained for 10 seconds, and the compression load immediately thereafter was read as the 50% compression load. The results are shown in Tables 1 and 2.

[0059] 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 3 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.

[0060] As shown in Table 1, the flexural modulus of the foams according to each Example was 4.5 MPa or less. Therefore, the foams according to each Example were highly easy to attach to curved surfaces, and the ease of attachment to curved surfaces was particularly high for the foams according to Examples 1 to 4 and 10. On the other hand, as shown in Table 2, the flexural modulus of the foam according to Comparative Example 1 was greater than 4.5 MPa, and it was difficult to say that this foam was easy to attach to curved surfaces.

[0061] As shown in Table 1, the apparent density of the foams according to each Example was low, and it was understood that these foams were foamed in a desired state. On the other hand, the apparent density of the foam according to Comparative Example 2 was relatively high, and it was difficult to say that the foam state of Comparative Example 2 was in a desirable state compared to the foams according to each Example.

[0062]

[0063]

[0064] A first aspect of the present invention is a foam comprising a first component which is an olefin resin and a second component which contains at least one selected from the group consisting of a thermoplastic elastomer and an ethylene vinyl acetate copolymer, wherein a kneaded product of 5 mass % of the foam and 95 mass % of polypropylene is molded into a sheet-like sample having a thickness of 200 μm, and the sheet-like sample has a thickness of 1 cm in a plan view. 2 a ratio of an area occupied by a portion where a heterogeneous portion forming a dispersed phase is present to an area of ​​the foam of 10% or less, and the foam has a flexural modulus of elasticity of 4.5 MPa or less.

[0065] A second aspect of the present invention provides the foam according to the first aspect, wherein the content of the olefin resin in the foam is 10% by mass to 40% by mass.

[0066] A third aspect of the present invention provides the foam according to the first or second aspect, wherein the olefin resin includes at least one selected from the group consisting of polyethylene and polypropylene.

[0067] A fourth aspect of the present invention provides the foam according to any one of the first to third aspects, wherein the content of the second component in the foam is 50% by mass to 90% by mass.

[0068] A fifth aspect of the present invention provides the foam according to any one of the first to fourth aspects, wherein the second component includes a thermoplastic elastomer including ethylene propylene rubber (EPDM).

[0069] A sixth aspect of the present invention provides a foam according to any one of the first to fifth aspects, wherein the second component includes the ethylene vinyl acetate copolymer.

[0070] A seventh aspect of the present invention provides a foam having a thickness of 3 mm or more in any one of the first to sixth aspects.

[0071] An eighth aspect of the present invention provides a member comprising: a foam according to any one of the first to seventh aspects; and a pressure-sensitive adhesive layer covering at least one surface of the foam.

Claims

1. A foam comprising a first component which is an olefin resin and a second component which contains at least one selected from the group consisting of a thermoplastic elastomer and an ethylene vinyl acetate copolymer, wherein a 1 cm2 surface area in a plan view of a sheet-like sample obtained by molding a mixture of 5% by mass of the foam and 95% by mass of polypropylene to a thickness of 200 μm is 2 a ratio of an area occupied by a portion where a heterogeneous portion forming a dispersed phase is present to an area of the foam of 10% or less, and the foam has a flexural modulus of 4.5 MPa or less.

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

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

4. The foam according to claim 1, wherein the content of the second component in the foam is 50% by mass to 90% by mass.

5. The foam of claim 1, wherein the second component comprises a thermoplastic elastomer comprising ethylene propylene rubber (EPDM).

6. The foam of claim 1, wherein the second component comprises the ethylene vinyl acetate copolymer.

7. The foam according to claim 1, having a thickness of 3 mm or more.

8. A member comprising the foam according to claim 1 and an adhesive layer covering at least one surface of the foam.

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