CN114585670A

CN114585670A - Resin foam

Info

Publication number: CN114585670A
Application number: CN202080074465.5A
Authority: CN
Inventors: 儿玉清明; 伊关亮; 佐佐木彰吾
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2019-11-25
Filing date: 2020-11-25
Publication date: 2022-06-03
Also published as: WO2021106912A1; CN114641521A; WO2021106913A1; CN114761473A; WO2021106914A1; CN114616278A; WO2021106911A1; JPWO2021106913A1; JPWO2021106912A1; KR20220106752A; CN114761474A; JPWO2021106910A1; WO2021106910A1; JPWO2021106914A1; JPWO2021106911A1

Abstract

The present invention provides a resin foam which is thin, has excellent impact absorbability and excellent flame retardancy. Apparent density of the resin foam of the present inventionThe degree is 0.02g/cm³～0.5g/cm³25% compressive load of 3N/cm²The above residue R at 650 ℃ is 20% by weight or more and has a bubble structure. In one embodiment, the resin foam has an elastic strain energy of 10kPa or more when compressed. In one embodiment, the aspect ratio of the cells of the resin foam is 1.5 or more.

Description

Resin foam

Technical Field

The present invention relates to a resin foam.

Background

Resin foams are used in large quantities as cushioning materials for protecting screens of electronic devices, substrates, and the like. In recent years, in response to the tendency of thinning of electronic devices, a cushioning material is required to exhibit high impact absorbability even when it is disposed at a position where a gap is narrow. Further, the use of the battery around the battery is increasing, and it is also required to cope with the ignition accident of the battery, that is, to have flame retardancy.

Patent document 1 discloses a method for obtaining a resin foam having excellent impact absorbability. However, there is no disclosure or suggestion in this publication about imparting flame retardancy. Patent document 2 discloses a method for obtaining a resin foam having a thin layer and excellent impact absorbability. However, although these publications clearly describe the impact absorbability, they do not disclose or suggest any means for imparting flame retardancy. In addition, patent document 3 discloses a method for obtaining a resin foam having flame retardancy. However, these publications do not disclose or suggest any thin layer and impart high impact absorbency.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2017-186504

Patent document 2: japanese patent laid-open publication No. 2015-034299

Patent document 3: japanese patent laid-open No. 2020 and 033519 publications

Disclosure of Invention

Problems to be solved by the invention

The present invention addresses the problem of providing a resin foam that is thin, has excellent impact absorption, and has excellent flame retardancy.

Means for solving the problems

The apparent density of the resin foam of the present invention is 0.02g/cm³～0.5g/cm³25% compressive load of 3N/cm²The above residue R at 650 ℃ is 20% by weight or more and has a bubble structure.

In one embodiment, the resin foam has an elastic strain energy of 10kPa or more when compressed.

In one embodiment, the non-foaming bending stress of the resin foam is 5MPa or more.

In one embodiment, the resin foam has a thickness recovery rate of 70% or more.

In one embodiment, the aspect ratio of the cells of the resin foam is 1.5 or more.

In one embodiment, the resin foam has an average cell diameter of 10 to 200 μm.

In one embodiment, the resin foam has a cell ratio of 30% or more.

In one embodiment, the coefficient of variation of the cell diameter of the resin foam is 0.5 or less.

In one embodiment, the thickness of the cell wall of the resin foam is 0.1 to 10 μm.

In one embodiment, the resin foam includes a polyolefin resin.

In one embodiment, the above polyolefin-based resin is a mixture of a polyolefin other than the polyolefin-based elastomer and the polyolefin-based elastomer.

In one embodiment, the resin foam has a heat-fusible layer on one or both surfaces thereof.

According to another aspect of the present invention, there is provided a foamed member having a resin foamed layer and an adhesive layer disposed on at least one side of the resin foamed layer, the resin foamed layer being the above-described resin foam.

ADVANTAGEOUS EFFECTS OF INVENTION

A resin foam which is thin, has excellent impact absorption, and has excellent flame retardancy.

Drawings

Fig. 1 is a schematic sectional view of a foaming member according to an embodiment of the present invention.

Description of the symbols

100 foamed member

10 resin foaming layer

20 adhesive layer

Detailed Description

A. Resin foam

The resin foam of the present invention has an apparent density D of 0.02g/cm³～0.5g/cm³25% compressive load of 3N/cm²The residue R at 650 ℃ is not less than 20% by weight. The resin foam of the present invention has a cell structure (pore structure). Examples of the bubble structure (pore structure) include an independent bubble structure, an interconnected bubble structure, and a semi-interconnected and semi-independent bubble structure (a bubble structure in which an independent bubble structure and an interconnected bubble structure are present in a mixed state). The cell structure of the resin foam is preferably an open cell structure or a semi-closed and semi-closed cell structure, and more preferably a semi-closed and semi-closed cell structure. The resin foam of the present invention is obtained by foaming a resin composition. The resin composition is a composition containing at least a resin constituting a resin foam.

As described above, the resin foam of the present invention has an apparent density D of 0.02g/cm³～0.5g/cm³. When the amount is within such a range, a resin foam having excellent flexibility and stress dispersibility can be obtained. The apparent density D of the resin foam of the present invention is preferably 0.04g/cm³～0.4g/cm³More preferably 0.06g/cm³～0.3g/cm³More preferably 0.08g/cm³～0.25g/cm³Particularly preferably 0.1g/cm³～0.2g/cm³Most preferably 0.13g/cm³～0.2g/cm³. If it is in such a range, thenThe above effect becomes remarkable. The method of measuring the apparent density will be described later.

As described above, the 25% compressive load of the resin foam of the present invention is 3N/cm²The above. When the amount is in this range, a resin foam is obtained which is less likely to undergo compression deformation even when subjected to a high impact. Since the resin foam of the present invention is not easily deformed, when the resin foam is applied to a device, a member (substrate, battery, or the like) around an application position is not deformed, and a failure of the member can be prevented. The 25% compression load of the resin foam is preferably 3.2N/cm²Above, more preferably 3.5N/cm²Above, more preferably 4N/cm²The above. If the range is such, the above-mentioned effect becomes remarkable. The upper limit of the 25% compressive load of the resin foam of the present invention is, for example, 10N/cm²(preferably 20N/cm)²). The method of measuring the 25% compression load will be described later.

As described above, the resin foam of the present invention has a residue R at 650 ℃ of 20% by weight or more. The resin foam having a residue at 650 ℃ in such a range has a low resin ratio and excellent flame retardancy. The resin foam preferably has a residue R at 650 ℃ of 25 wt% or more, more preferably 30 wt% or more. When the amount is in such a range, a resin foam having more excellent flame retardancy can be obtained. The upper limit of the residue R at 650 ℃ of the resin foam is, for example, 50 wt% (preferably 60 wt%, more preferably 70 wt%). The residue R is a residue at 650 ℃ when the resin foam is heated in a nitrogen atmosphere at a heating rate of 20 ℃/min in a measurement range of 25 ℃ to 680 ℃. The residue R can be measured, for example, using the trade name "TG/DTA 6200" manufactured by SII Nanotechnology. In one embodiment, the residue R may be an inorganic component (e.g., an inorganic filler) contained in the resin foam.

In the present invention, by setting the apparent density D, 25% compression load and residue R in the above ranges, a resin foam having excellent impact absorbability and excellent flame retardancy can be provided. The resin foam of the present invention exhibits excellent impact absorbability even when it is thin, and therefore can be applied to a position where the gap is narrow.

In one embodiment, the apparent density D (g/cm)³) And the residue R (%) at 650 ℃ satisfy the following formula (1).

1≤{(100-R)/D}/100≤10···(1)

The apparent density D (g/cm) is preferably³) And the residue R (%) at 650 ℃ satisfy the following formula (2), and the apparent density D (g/cm) is more preferable³) And the residue R (%) at 650 ℃ satisfy the following formula (3), and the apparent density D (g/cm) is more preferable³) And the residue R (%) at 650 ℃ satisfy the following formula (4). When the apparent density D and the residue R are in such a relationship, a resin foam having a high balance between stress dispersibility and flame retardancy can be obtained.

2≤{(100-R)/D}/100≤9.5···(2)

3≤{(100-R)/D}/100≤8.5···(3)

3.5≤{(100-R)/D}/100≤8···(4)

The 50% compression load of the resin foam is preferably 5N/cm²As described above. When the amount is in this range, a resin foam having an appropriate hardness and being less likely to undergo compression deformation even when subjected to a high impact force can be obtained. The 50% compression load of the resin foam is more preferably 7N/cm²Above, further preferably above 9N/cm²Particularly preferably 10N/cm²The above. If the range is such, the above-mentioned effect becomes remarkable. The upper limit of the 50% compression load of the resin foam is preferably 50N/cm²More preferably 40N/cm²More preferably 30N/cm²Particularly preferably 25N/cm². If the range is within this range, the repulsive force when applied to the gap (particularly, a gap with a narrow gap) can be appropriately suppressed, and adverse effects on the peripheral members can be prevented.

The compressive modulus of the resin foam is preferably 200kPa or more. When the amount is within this range, a resin foam is obtained which is less likely to undergo compression deformation and is less likely to break even when subjected to a high impact force. The compressive modulus of the resin foam is preferably 220kPa or more, more preferably 250kPa or more, and still more preferably 300kPa or more. If the range is such, the above-mentioned effect becomes remarkable. The upper limit of the compressive modulus of the resin foam is preferably 1000kPa, more preferably 800kPa, and still more preferably 600 kPa. The compression rate (%) and compression rebound force (kPa) of the resin foam were measured based on one compression test of JIS K6767, and the compression modulus of the resin foam was calculated from F (5%) and F (15%) by the formula (F (15%))/(15-5) × 100 by reading the compression rebound force F (5%) at a compression rate of 5% and the rebound force F (15%) at a compression rate of 15%, respectively.

The resin foam preferably has an elastic strain energy of 10kPa or more when compressed. The "elastic strain energy in compression" refers to the total amount of compression rebound force when the resin foam is compressed by 10%. Specifically, when the compression ratio (%) and the compression rebound force (kPa) of the resin foam are measured by a compression test (test temperature: 23 ℃, sample size: 10mm × 10mm, compression speed: 10mm/min) according to JIS K6767, the "elastic strain energy under compression" is obtained from a compression ss curve in which the x-axis is the compression ratio (%) and the y-axis is the compression rebound force (kPa), and the "elastic strain energy under compression" is the area of a region defined by the ss curve and the x-axis in the range of 0% to 10% of the compression ratio. When the elastic strain energy of the resin foam during compression is in the above range, a resin foam having excellent impact absorbability can be obtained. More specifically, the resin foam having an elastic strain energy in the above range consumes a large amount of energy when an impact is applied, and therefore, the resin foam can absorb a strong impact satisfactorily. The elastic strain energy of the resin foam under compression is more preferably 20kPa or more, still more preferably 30kPa or more, still more preferably 50kPa or more, still more preferably 60kPa or more, still more preferably 80kPa or more, particularly preferably 100kPa or more, and most preferably 150kPa or more. If the range is such, the above-mentioned effect becomes remarkable. The upper limit of the elastic strain energy of the resin foam under compression is, for example, 500kPa (preferably 800 kPa).

The non-foaming bending stress of the resin foam is preferably 5MPa or more, more preferably 6MPa or more, further preferably 9MPa or more, and particularly preferably 10MPa or more. If the amount is within this range, a large amount of energy is required to deform the cell walls (cell walls) of the resin foam, and a resin foam having excellent impact absorbability can be obtained. The resin foam described above can improve impact resistance (impact absorbability) by appropriately reducing flexibility, which has been regarded as important in conventional cushioning materials, and by achieving a balance with other properties. As described above, the above resin foam exhibiting impact absorbability by action different from the conventional one is particularly useful in a configuration in which an impact is transmitted in a narrow range (a configuration in which an impact is not easily diffused in a plane direction), and is particularly useful when applied to a member having flexibility (for example, a member made of a resin). The upper limit of the non-foaming bending stress is preferably 20MPa, more preferably 15 MPa. When the amount is within such a range, a resin foam having more excellent flexibility and stress dispersibility can be obtained. The "non-foaming bending stress" refers to the bending stress of the resin molded body a that is restored to a non-foaming state (block shape) without bubbles by hot-pressing the resin foam body. The density of the resin molded article a may be equal to the density of the resin molded article b before foaming, which is formed from the resin composition described later. The bending stress of the resin molded article a (non-foaming bending stress of the resin foam) may be the same as that of the resin molded article b. The method of measuring the bending stress will be described later.

The impact absorption rate of the resin foam is preferably 25% or more, more preferably 30% or more, and further preferably 35% or more. The impact absorption rate was measured as follows.

A resin foam, a double-sided tape (model No.5603W, manufactured by Nindon electric Co., Ltd.), and a PET film (model No. DIAFOIL MRF75, manufactured by Mitsubishi resin) were disposed in this order on the impact force sensor to form a test piece. 66g of iron balls were dropped from a height of 50cm above the PET film to the test piece, and the impact force F1 was measured.

Further, the iron ball was directly dropped to the impact force sensor as described above, and the impact force F0 of the blank was measured.

The impact absorption (%) was calculated from F1 and F0 by the formula (F0-F1)/F0X 100.

The thickness recovery of the resin foam is preferably 70% or more, more preferably 75% or more, and still more preferably 80% or more. The thickness recovery rate of the foamed layer is defined by the following formula. The thickness recovery rate of the foamed layer is a recovery rate measured by applying a load to a foamed sheet over a certain area and compressing the foamed sheet, and is different from a so-called sag recovery rate measured by partially applying a load and sagging only a part of the foamed sheet.

Thickness recovery rate (%) { (thickness after 0.5 seconds from the decompressed state)/(initial thickness) } × 100

Initial thickness: thickness of the resin foam before application of load.

Thickness 0.5 seconds after releasing the compressed state: applying 1000g/cm to the resin foam²The pressure was maintained for 120 seconds, and the compression was released, thereby releasing the thickness of the resin foam after 0.5 seconds of compression.

The resin foam of the present invention preferably has a thickness change rate of 10% or less by repeated compression. When the amount is within this range, a resin foam which is not easily broken, prevents a gap from surrounding members when used as a cushioning material, and has excellent dust resistance can be obtained. The thickness change rate of the resin foam due to repeated compression is more preferably 8% or less, still more preferably 5% or less, particularly preferably 3% or less, and most preferably 1% or less. If the range is such, the above-mentioned effect becomes remarkable. The lower limit of the thickness change rate of the resin foam due to repeated compression is preferably as small as possible, and is, for example, 0.5% (preferably 0.3%, more preferably 0.1%, and still more preferably 0.05%). The thickness change rate of the resin foam due to repeated compression is: a disk jig (contact area: 4.9 cm) having a flat front end was attached²) The rate of change in thickness when the resin foam was pressed and subjected to 5000 cycles of 50% compression/10% compression (thickness basis). The change rate was calculated by the formula (thickness before test) - (thickness after test) }/(thickness before test) × 100.

The tensile modulus at 23 ℃ of the resin foam is preferably 0.6MPa or more, more preferably 0.7MPa to 5MPa, and still more preferably 1MPa to 4 MPa. When the content is in such a range, a resin foam having excellent stress dispersibility and exhibiting excellent impact absorbability even in the form of a thin film can be obtained. The tensile modulus was determined from the slope of a straight line connecting the origin of the tensile strain-tensile strength curve obtained by fixing a sample (size: 10 mm. times.80 mm) at an inter-chuck distance of 40mm and performing a tensile test at a tensile speed of 500 mm/min.

The resin foam preferably has an elongation at break at 25 ℃ of 120% or less, more preferably 110% or less, still more preferably 100% or less, and particularly preferably 90% or less. When the amount is within such a range, a resin foam having excellent flexibility and stress dispersibility can be obtained. When the elongation at break is small and a load is applied to the resin foam, the deformation of the pore walls of the resin foam is small, and for example, when a filler is added, sliding is likely to occur at the interface between the resin constituting the resin foam and the filler, and the load can be further alleviated. On the other hand, if the elongation at break is too large, the deformation of the pore walls of the resin foam becomes large, and it may become difficult to relax the load. The elongation at break can be measured based on JIS K6767.

The stress retention of the resin foam is preferably 60% or more, more preferably 63% to 100%, and still more preferably 63% to 95%. When the content is in such a range, a resin foam having excellent stress dispersibility and exhibiting excellent impact absorbability even in the form of a thin film can be obtained. In the present specification, the above-mentioned stress retention ratio is a ratio of a tensile strength immediately after stretching to a tensile strength after 12 hours after holding at a rate of 300m/min (tensile strength after 12 hours/tensile strength immediately after stretching × 100) in which a resin foam (width 10mm × length 100mm) is stretched by 20% in a longitudinal direction.

The thickness of the resin foam is preferably 30 to 5000. mu.m, more preferably 35 to 4000. mu.m, still more preferably 40 to 3000. mu.m, yet more preferably 45 to 2000. mu.m, particularly preferably 50 to 1000. mu.m, most preferably 55 to 500. mu.m. As described above, the resin foam of the present invention exhibits excellent impact resistance although it is a thin layer. In addition, if the thickness of the resin foam is within the above range, a fine and uniform cell structure can be formed, which is advantageous in that excellent impact absorbability can be exhibited.

The horizontal burning distance of the resin foam is preferably 140mm or less, more preferably 130mm or less, further preferably 110mm or less, and particularly preferably 90mm or less. The lower limit of the horizontal burning distance of the resin foam is preferably as short as possible, and is, for example, 30mm (preferably 20mm, more preferably 10mm, and still more preferably 5 mm). The horizontal burning distance can be measured according to the flame retardant test method for foams described in UL 94.

The average cell diameter (average pore diameter) of the resin foam is preferably 10 to 200. mu.m, more preferably 15 to 180 μm, still more preferably 20 to 150 μm, yet more preferably 23 to 120 μm, particularly preferably 25 to 100 μm, and most preferably 30 to 80 μm. When the amount is within this range, a resin foam which does not deform excessively upon receiving an impact and can exhibit high impact absorbability can be obtained. Further, a resin foam having an appropriate hardness and suitable as a cushioning material for filling the gap can be obtained. The method of measuring the average bubble diameter is described later.

The aspect ratio of the cells of the resin foam is preferably 1.5 or more. When the amount is within such a range, a resin foam having excellent thickness recovery properties can be obtained. The aspect ratio of the cells constituting the resin foam is preferably 2.0 or more, and more preferably 2.5 or more. If the range is such, the above-mentioned effect becomes remarkable. The upper limit of the aspect ratio of the cells constituting the resin foam is preferably 5, more preferably 4, and still more preferably 3.5. When the amount is within such a range, a resin foam having excellent impact absorbability can be obtained.

In the present specification, the term "aspect ratio of cells contained in the resin foam" means that the cells are randomly selectedA predetermined area (3 mm) in the cross section of the resin foam at the portion of (A)²) Average value of aspect ratio of each bubble present in the range. The specific method of obtaining "aspect ratio of cells in the resin foam" is as follows.

The resin foam is cut along the TD (direction orthogonal to the flow direction) and in the direction (thickness direction) perpendicular to the main surface of the resin foam using a razor, and a predetermined area (3 mm) is observed in a cross-section at a magnification of 100 times using a microscope (for example, "VHX-2000" manufactured by Keyence)²) And (3) a range. The thickness direction length and TD length of one bubble were measured.

The same measurement is performed for all the bubbles present in a given area.

The aspect ratio of the cells was calculated by dividing the length of TD by the length in the thickness direction, and the same calculation was performed for all the cells, and the average value was defined as "the aspect ratio of the cells contained in the resin foam".

The coefficient of variation of the cell diameter (cell diameter) of the resin foam is preferably 0.5 or less, more preferably 0.48 or less, still more preferably 0.45 or less, particularly preferably 0.43 or less, and most preferably less than 0.4. When the amount is within such a range, deformation due to impact becomes uniform, local stress load can be prevented, and a resin foam having excellent stress dispersibility and particularly excellent impact resistance can be obtained. The lower limit of the variation coefficient is preferably 0.2 (preferably 0.15, more preferably 0.1, and further preferably 0.01) as the variation coefficient is smaller. The method of measuring the coefficient of variation of the bubble diameter will be described later.

The resin foam preferably has a cell ratio (porosity) of 30% or more, more preferably 50% or more. When the amount is within this range, a resin foam having a small repulsive stress during compression can be obtained. In such a resin foam, when the resin foam is applied while being slightly compressed at a position where the gap is narrow, stress applied to other members can be reduced. For example, when the resin foam is used for a display member, stress applied to the display member can be relaxed and dispersed, and therefore, the resin foam is useful from the viewpoint of reducing color unevenness and protecting the member. The upper limit of the bubble content is preferably 99% or less, more preferably 95% or less, and still more preferably 90% or less. When the amount is within this range, a resin foam having an appropriate hardness, a small amount of deformation upon impact, and a high impact absorbability can be obtained. The method of measuring the bubble percentage will be described later.

The thickness of the cell walls (cell walls) of the resin foam is preferably 0.1 to 10 μm, more preferably 0.3 to 8 μm, still more preferably 0.5 to 5 μm, particularly preferably 0.7 to 4 μm, and most preferably 1 to 2.8 μm. When the amount is within this range, a resin foam which does not deform excessively upon receiving an impact and can exhibit high impact absorbability can be obtained. Further, a resin foam having an appropriate hardness and suitable as a cushioning material for filling the gap can be obtained. The method of measuring the thickness of the bubble wall will be described later.

When the foam structure of the resin foam is a semi-continuous semi-closed cell structure, the proportion of the closed cell structure is preferably 40% or less, more preferably 30% or less. When the amount is within this range, a resin foam having an appropriate hardness and suitable as a cushion material for filling the gap can be obtained. In the present specification, the closed cell ratio of the resin foam is determined, for example, as follows: the measurement object was allowed to sink in water in an environment at a temperature of 23 ℃ and a humidity of 50%, the mass after measurement was measured, and after sufficiently drying in an oven at 80 ℃, the mass was measured again. Further, if the cells are open cells, moisture can be retained, and therefore, the cells can be obtained as open cells by measuring the mass thereof.

The shape of the resin foam may be any suitable shape according to the purpose. Such a shape is typically a sheet shape.

The resin foam may have a heat-fusible layer on one or both surfaces thereof. The resin foam having the heat-melting layer can be obtained, for example, by rolling the resin foam (or the precursor of the resin foam) using a pair of heating rollers heated to a temperature equal to or higher than the melting temperature of the resin composition constituting the resin foam.

The resin foam may be formed by any appropriate method within a range not impairing the effects of the present invention. Such a method typically includes a method of foaming a resin composition containing a resin material (polymer).

A-1. resin composition

The resin foam of the present invention can be typically obtained by foaming a resin composition. The resin composition comprises any suitable resin material (polymer).

Examples of the polymer include: acrylic resins, silicone resins, urethane resins, polyolefin resins, ester resins, rubber resins, and the like. The above-mentioned polymers may be used alone or in combination of two or more.

The content ratio of the polymer is preferably 30 to 95 parts by weight, more preferably 35 to 90 parts by weight, still more preferably 40 to 80 parts by weight, and particularly preferably 40 to 60 parts by weight, based on 100 parts by weight of the resin composition. When the amount is within such a range, a resin foam having more excellent flexibility and stress dispersibility can be obtained.

In one embodiment, a polyolefin-based resin is used as the polymer.

The content ratio of the polyolefin-based resin is preferably 50 to 100 parts by weight, more preferably 70 to 100 parts by weight, still more preferably 90 to 100 parts by weight, particularly preferably 95 to 100 parts by weight, and most preferably 100 parts by weight, based on 100 parts by weight of the polymer.

The polyolefin-based resin is preferably at least one selected from the group consisting of polyolefins and polyolefin-based elastomers, and more preferably a polyolefin and a polyolefin-based elastomer are used in combination. The polyolefin and the polyolefin elastomer may be used alone or in combination of two or more. In the present specification, when a "polyolefin" is referred to, the "polyolefin elastomer" is not included.

When a polyolefin and a polyolefin elastomer are used in combination as a polyolefin resin, the weight ratio of the polyolefin to the polyolefin elastomer (polyolefin/polyolefin elastomer) is preferably 1/99 to 99/1, more preferably 10/90 to 90/10, still more preferably 20/80 to 80/20, and particularly preferably 30/70 to 70/30. In such a range, the effect of the present invention becomes remarkable.

As the polyolefin, any suitable polyolefin may be used within a range not impairing the effects of the present invention. Examples of such polyolefins include: linear polyolefins, branched (branched) polyolefins, and the like. In one embodiment, a branched polyolefin is used as the polyolefin-based resin. In this embodiment, the polyolefin may be a branched polyolefin alone or a combination of a branched polyolefin and a linear polyolefin. By using a branched polyolefin, a resin foam having a small average cell diameter and excellent impact resistance can be obtained. The content ratio of the branched polyolefin is preferably 30 to 100 parts by weight, more preferably 80 to 120 parts by weight, based on 100 parts by weight of the polyolefin.

Examples of the polyolefin include: a polymer comprising structural units derived from an alpha-olefin. The polyolefin may be composed of only a structural unit derived from an α -olefin, or may be composed of a structural unit derived from an α -olefin and a structural unit derived from a monomer other than an α -olefin. When the polyolefin is a copolymer, any suitable copolymerization method can be used as the copolymerization method. Examples thereof include: random copolymers, block copolymers, and the like.

The α -olefin that can constitute the polyolefin is preferably, for example, an α -olefin having 2 to 8 (preferably 2 to 6, more preferably 2 to 4) carbon atoms (for example, ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene, 1-octene, etc.). The α -olefin may be only one kind or two or more kinds.

Examples of the monomer other than the α -olefin constituting the polyolefin include: ethylenically unsaturated monomers such as vinyl acetate, acrylic acid esters, methacrylic acid esters, and vinyl alcohol. The monomer other than the α -olefin may be only one kind or two or more kinds.

Specific examples of the polyolefin include: low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene (propylene homopolymer), a copolymer of ethylene and propylene, a copolymer of ethylene and an α -olefin other than ethylene, a copolymer of propylene and an α -olefin other than propylene, a copolymer of ethylene, propylene and an α -olefin other than ethylene and propylene, a copolymer of propylene and an ethylenically unsaturated monomer, and the like.

In one embodiment, as the polyolefin, a polypropylene-based polymer having a structural unit derived from propylene is used. Examples of the polypropylene-based polymer include: polypropylene (propylene homopolymer), a copolymer of ethylene and propylene, a copolymer of propylene and an α -olefin other than propylene, and the like, and polypropylene (propylene homopolymer) is preferred. The polypropylene-based polymer may be used alone or in combination of two or more.

From the viewpoint of further exhibiting the effect of the present invention, the Melt Flow Rate (MFR) of the polyolefin at 230 ℃ is preferably from 0.2g/10 min to 10g/10 min, more preferably from 0.25g/10 min to 5g/10 min, further preferably from 0.3g/10 min to 3g/10 min, particularly preferably from 0.35g/10 min to 1.5g/10 min. In the present specification, the Melt Flow Rate (MFR) is an MFR measured at a temperature of 230 ℃ under a load of 2.16kgf in accordance with ISO1133 (JIS-K-7210).

In one embodiment, two or more different polyolefins having Melt Flow Rates (MFR) at a temperature of 230 ℃ within the above-described range are used in combination. In this case, a polyolefin having a Melt Flow Rate (MFR) at a temperature of 230 ℃ of preferably 0.2g/10 min or more and less than 0.7g/10 min (more preferably 0.2g/10 min to 0.65g/10 min) and a polyolefin having a Melt Flow Rate (MFR) at a temperature of 230 ℃ of preferably 0.7g/10 min to 10g/10 min (more preferably 0.7g/10 min to 5g/10 min, further preferably 0.7g/10 min to 3g/10 min, particularly preferably 0.7g/10 min to 1.5g/10 min, most preferably 0.7g/10 min to 1.3g/10 min) may be used in combination. Thus, a resin foam having a small average cell diameter and excellent impact resistance can be obtained.

When two or more different polyolefins having a Melt Flow Rate (MFR) at 230 ℃ in the above-mentioned range are used in combination as the polyolefin, for example, the weight ratio of the polyolefin having a Melt Flow Rate (MFR) at 230 ℃ of preferably 0.2g/10 min or more and less than 0.7g/10 min (more preferably 0.2g/10 min to 0.65g/10 min) to the polyolefin having a Melt Flow Rate (MFR) at 230 ℃ of preferably 0.7g/10 min to 10g/10 min (more preferably 0.7g/10 min to 5g/10 min, further preferably 0.7g/10 min to 3g/10 min, particularly preferably 0.7g/10 min to 1.5g/10 min, most preferably 0.7g/10 min to 1.3g/10 min) is preferably 1/99 to 99/1, More preferably 10/90-90/10, still more preferably 20/80-80/20, particularly preferably 30/70-70/30, and most preferably 40/60-60/40.

As the polyolefin, commercially available products can be used, and examples thereof include: "E110G" (manufactured by Priman Polymer K.K.), "EA 9" (manufactured by Nippon Polypropylene K.K.), "EA 9 FT" (manufactured by Nippon Polypropylene K.K.), "E-185G" (manufactured by Priman Polymer K.K.), "WB 140 HMS" (manufactured by Borealis) and "WB 135 HMS" (manufactured by Borealis).

As the polyolefin-based elastomer, any suitable polyolefin-based elastomer may be used within a range not impairing the effects of the present invention. Examples of such polyolefin-based elastomers include: so-called non-crosslinked thermoplastic olefin elastomers (TPO) such as ethylene-propylene copolymers, ethylene-propylene-diene copolymers, ethylene-vinyl acetate copolymers, polybutenes, polyisobutylenes, chlorinated polyethylenes, elastomers obtained by physically dispersing polyolefin components and rubber components, and elastomers having a structure in which polyolefin components and rubber components are microphase-separated; a dynamically crosslinked thermoplastic olefin elastomer (TPV) obtained by dynamically heat-treating a mixture containing a matrix-forming resin component a (olefin-based resin component a) and a domain-forming rubber component B in the presence of a crosslinking agent; and the like, and the dynamic crosslinking thermoplastic olefin-based elastomer is a polymer having a multiphase system of a sea-island structure in which crosslinked rubber particles are finely dispersed as domains (island phases) in a resin component A as a matrix (sea phase).

The polyolefin-based elastomer preferably contains a rubber component. Examples of such rubber components include those described in Japanese patent laid-open Nos. H08-302111, 2010-241934, 2008-024882, 2000-007858, 2006-052277, 2012-072306, 2012-057068, 2010-241897, 2009-067969, and JP-B-03/002654.

Specific examples of the elastomer having a structure in which a polyolefin component and an olefinic rubber component are microphase-separated include: an elastomer formed of a polypropylene resin (PP) and an ethylene-propylene rubber (EPM), an elastomer formed of a polypropylene resin (PP) and an ethylene-propylene-diene rubber (EPDM), and the like. The weight ratio of the polyolefin component to the olefin rubber component (polyolefin component/olefin rubber) is preferably 90/10 to 10/90, more preferably 80/20 to 20/80.

In general, a dynamically crosslinked thermoplastic olefin elastomer (TPV) has a high modulus of elasticity and a small compression set as compared with a non-crosslinked thermoplastic olefin elastomer (TPO). This provides a foam having good recovery properties, and excellent recovery properties can be exhibited when the foam is produced.

The dynamically crosslinked thermoplastic olefin elastomer (TPV) is a polymer of a multiphase system having a sea-island structure in which crosslinked rubber particles are finely dispersed as domains (island phases) in the resin component a as a matrix (sea phase) obtained by dynamically heat treating a mixture containing the resin component a forming the matrix (olefin-based resin component a) and the rubber component B forming the domains in the presence of a crosslinking agent as described above.

Examples of the dynamically crosslinked thermoplastic olefin elastomer (TPV) include: disclosed is a dynamically crosslinked thermoplastic olefin elastomer described in, for example, Japanese patent application laid-open Nos. 2000-007858, 2006-052277, 2012-072306, 2012-057068, 2010-241897, 2009-067969 and 03/002654.

As the dynamic crosslinking thermoplastic olefin elastomer (TPV), commercially available products can be used, and examples thereof include: "Zeotherm" (manufactured by Nippon corporation), "THERMOUN" (manufactured by Mitsubishi chemical corporation), "Sarlink 3245D" (manufactured by Toyo Boseki Co., Ltd.), and the like.

The Melt Flow Rate (MFR) of the polyolefin-based elastomer at 230 ℃ is preferably 2g/10 min to 15g/10 min, more preferably 3g/10 min to 10g/10 min, still more preferably 3.5g/10 min to 9g/10 min, particularly preferably 4g/10 min to 8g/10 min, and most preferably 4.5g/10 min to 7.5g/10 min.

The melt tension (at 190 ℃ C., at break) of the polyolefin-based elastomer is preferably less than 10cN, more preferably 5cN to 9.5 cN.

The JIS a hardness of the polyolefin-based elastomer is preferably 30 ° to 95 °, more preferably 35 ° to 90 °, even more preferably 40 ° to 88 °, particularly preferably 45 ° to 85 °, and most preferably 50 ° to 83 °. The JIS a hardness is measured according to ISO7619(JIS K6253).

In one embodiment, the resin foam (i.e., the resin composition) may further contain a filler. By containing the filler, a resin foam which requires a large energy to deform the cell walls (cell walls) can be formed, and the resin foam exhibits excellent impact absorbability. In addition, the inclusion of the filler enables the formation of a fine and uniform bubble structure, and is also advantageous in that excellent impact absorbability can be exhibited. The filler may be used alone or in combination of two or more.

The content ratio of the filler is preferably 10 to 150 parts by weight, more preferably 30 to 130 parts by weight, and still more preferably 50 to 100 parts by weight, based on 100 parts by weight of the polymer constituting the resin foam. If the range is such, the above-mentioned effect becomes remarkable.

In one embodiment, the filler is an inorganic substance. Examples of the material constituting the filler as an inorganic substance include: aluminum hydroxide, magnesium hydroxide, calcium carbonate, magnesium carbonate, calcium silicate, magnesium silicate, calcium oxide, magnesium oxide, aluminum nitride, aluminum borate whisker, silicon nitride, boron nitride, crystalline silica, amorphous silica, metal (e.g., gold, silver, copper, aluminum, nickel), carbon, graphite, or the like.

In one embodiment, the filler is organic. Examples of the material constituting the filler as an organic material include: polymethyl methacrylate (PMMA), polyimide, polyamideimide, polyether ether ketone, polyetherimide, polyesterimide, and the like.

As the filler, a flame retardant may be used. Examples of the flame retardant include: bromine flame retardants, chlorine flame retardants, phosphorus flame retardants, antimony flame retardants, and the like. From the viewpoint of safety, a halogen-free and antimony-free flame retardant is preferably used.

Examples of the halogen-free and antimony-free flame retardant include: compounds containing aluminum, magnesium, calcium, nickel, cobalt, tin, zinc, copper, iron, titanium, boron, and the like. Examples of such a compound (inorganic compound) include: hydrated metal compounds such as aluminum hydroxide, magnesium oxide/nickel oxide hydrate, and magnesium oxide/zinc oxide hydrate.

Any suitable surface treatment may be applied to the filler material. Examples of such surface treatment include: silane coupling treatment, stearic acid treatment, and the like.

The packing material preferably has a bulk density of 0.8g/cm³Less than, more preferably 0.6g/cm³The concentration is preferably 0.4g/cm or less³Below, particularly preferably 0.3g/cm³The following. If the content is within such a range, the filler can be contained with good dispersibility, and the filler addition effect can be sufficiently exhibited even if the content of the filler is reduced. A resin foam having a small content of a filler is advantageous in terms of high foaming, softness, and excellent stress dispersion and appearance. The lower limit of the bulk density of the filler is, for example, 0.01g/cm³Preferably 0.05g/cm³More preferably 0.1g/cm³。

The number average particle diameter (primary particle diameter) of the filler is preferably 5 μm or less, more preferably 3 μm or less, and still more preferably 1 μm or less. When the amount is in such a range, the filler can be contained with good dispersibility, and a uniform bubble structure can be formed. As a result, a resin foam having excellent stress dispersibility and appearance can be obtained. The lower limit of the number average particle diameter of the filler is, for example, 0.1. mu.m. The number average particle size of the filler can be measured using a particle size distribution meter (mictraci, MICROTRAC BEL) using a sample prepared by mixing 1g of the filler with 100g of water.

The specific surface area of the filler is preferably 2m²A value of at least g, more preferably 4m²A total of at least g, more preferably 6m²More than g. When the amount is in such a range, the filler can be contained with good dispersibility, and a uniform bubble structure can be formed. As a result, a resin foam having excellent stress dispersibility and appearance can be obtained. The upper limit of the specific surface area of the filler is, for example, 20m²(ii) in terms of/g. The specific surface area of the filler can be measured by the BET method, that is, by causing molecules having a known adsorption occupied area to adsorb to the surface of the filler at a low temperature using liquid nitrogen, and measuring according to the adsorption amount thereof.

Any suitable other component may be contained in the resin composition within a range not impairing the effects of the present invention. Such other components may be only one kind, or two or more kinds. Examples of such other components include: rubber, a resin other than a polymer blended as a resin material, a softening agent, an aliphatic compound, an antioxidant, a light stabilizer, a weather resistant agent, an ultraviolet absorber, a dispersant, a plasticizer, carbon, an antistatic agent, a surfactant, a crosslinking agent, a thickener, an antirust agent, a silicone compound, a tension modifier, a shrinkage inhibitor, a fluidity modifier, a gelling agent, a curing agent, a reinforcing agent, a foaming agent, a foam nucleating agent, a colorant (a pigment, a dye, etc.), a pH adjuster, a solvent (an organic solvent), a thermal polymerization initiator, a photopolymerization initiator, a lubricant, a crystal nucleating agent, a crystallization accelerator, a vulcanizing agent, a surface treatment agent, a dispersion aid, and the like.

A-2 formation of resin foam

The resin foam of the present invention is typically obtained by foaming a resin composition. As the foaming method (method of forming bubbles), a method generally used for foam molding such as a physical method or a chemical method can be used. That is, the resin foam may be a foam (physical foam) formed by foaming by a physical method, or a foam (chemical foam) formed by foaming by a chemical method, as a representative example. The physical method is generally a method of dispersing a gas component such as air or nitrogen in a polymer solution and forming bubbles by mechanical mixing (mechanical foam). The chemical method is generally a method of obtaining a foam by forming pores by utilizing a gas generated by thermal decomposition of a foaming agent added to a polymer matrix.

The resin composition to be foam-molded can be prepared, for example, by mixing the constituent components by any suitable means such as an open type mixing roll, a non-open type banbury mixer, a single-screw extruder, a twin-screw extruder, a continuous mixer, and a pressure kneader.

< embodiment 1 to form a resin foam

As one embodiment 1 of forming the resin foam, for example, the following embodiments are given: the resin foam is formed through a step (step a) of mechanically foaming and foaming an emulsion resin composition (emulsion containing a resin material (polymer) or the like). Examples of the foaming device include: a high-speed shearing type device, a vibration type device, a pressurized gas ejection type device, and the like. Among these foaming devices, a high-speed shearing type device is preferable from the viewpoint of the miniaturization of the bubble diameter and the large-volume production. The embodiment 1 of forming the resin foam can be applied to any resin composition.

From the viewpoint of film-forming properties, it is preferable that the emulsion has a high solid content concentration. The solid content concentration of the emulsion is preferably 30% by weight or more, more preferably 40% by weight or more, and further preferably 50% by weight or more.

The bubbles generated when foaming is carried out by mechanical stirring are generated by gas entering into the emulsion. As the gas, any appropriate gas may be used as long as it is inactive with respect to the emulsion, within a range not impairing the effect of the present invention. Examples of such a gas include: air, nitrogen, carbon dioxide, and the like.

The resin foam of the present invention can be obtained by a step (step B) of applying an emulsion resin composition (foam-containing emulsion resin composition) foamed by the above method to a substrate and drying the composition. Examples of the substrate include: a plastic film subjected to a peeling treatment (a polyethylene terephthalate film subjected to a peeling treatment, etc.), a plastic film (a polyethylene terephthalate film, etc.), and the like.

In the step B, any appropriate method may be employed as the coating method and the drying method within a range not impairing the effects of the present invention. The step B preferably includes: a pre-drying step B1 in which the foam-containing emulsion resin composition applied to the base material is dried at a temperature of 50 ℃ or higher and less than 125 ℃; and a main drying step B2 in which the substrate is further dried at a temperature of 125 to 200 ℃.

By providing the preliminary drying step B1 and the main drying step B2, the combination and integration of bubbles and the collapse of bubbles due to a rapid temperature rise can be prevented. In particular, in the case of a foamed sheet having a small thickness, the bubbles are united and broken by a rapid rise in temperature, and therefore, it is significant to provide the preliminary drying step B1. The temperature in the preliminary drying step B1 is preferably 50 to 100 ℃. The time of the preliminary drying step B1 is preferably 0.5 to 30 minutes, and more preferably 1 to 15 minutes. The temperature in the main drying step B2 is preferably 130 to 180 ℃ and more preferably 130 to 160 ℃. The time of the main drying step B2 is preferably 0.5 to 30 minutes, and more preferably 1 to 15 minutes.

< embodiment 2 to form a resin foam

As one embodiment 2 for forming the resin foam, there is a mode in which a resin composition is foamed with a foaming agent to form a foam. As the blowing agent, a blowing agent generally used in foam molding can be used, and from the viewpoint of environmental protection and low contamination of the foamed body, it is preferable to use a high-pressure inert gas.

As the inert gas, any appropriate inert gas can be used as long as it is inactive with respect to the resin composition and can be impregnated with the resin composition. Examples of such inert gas include: carbon dioxide, nitrogen, air, and the like. These gases may also be used in combination. Among these, carbon dioxide is preferable from the viewpoint of a large impregnation amount with respect to the resin material (polymer) and a high impregnation speed.

The inert gas is preferably in a supercritical state. That is, it is particularly preferable to use carbon dioxide in a supercritical state. In the supercritical state, the solubility of the inert gas in the resin composition is further increased, the inert gas can be mixed at a high concentration, and when the pressure is rapidly decreased, the inert gas becomes at a high concentration, so that the generation of cell nuclei becomes large, and even if the porosity is the same, the density of cells that can be formed by growing the cell nuclei becomes higher than that in the other state, so that fine cells can be obtained. The critical temperature of carbon dioxide was 31 ℃ and the critical pressure was 7.4 MPa.

Examples of the method for forming the foam by impregnating the resin composition with the high-pressure inert gas include a method of forming the foam through the following steps: a gas impregnation step of impregnating a resin composition containing a resin material (polymer) with an inert gas under high pressure; a pressure reducing step of reducing the pressure after the step to foam the resin material (polymer); and a heating step of growing bubbles by heating, if necessary. In this case, the non-foamed molded article molded in advance may be immersed in an inert gas, or the molten resin composition may be impregnated with an inert gas under pressure and then molded under reduced pressure. These steps may be carried out in any of a batch method and a continuous method. That is, a batch method may be employed in which a resin composition is molded into an appropriate shape such as a sheet in advance to form an unfoamed resin molded body, and then the unfoamed resin molded body is impregnated with a high-pressure gas and is released from the high-pressure gas to foam; the resin composition may be kneaded and molded under pressure together with a high-pressure gas, and the molding and foaming may be performed simultaneously by releasing the pressure.

An example of producing the foam in a batch manner is shown below. For example, a resin sheet for foam molding is produced by extruding a resin composition using an extruder such as a single-screw extruder or a twin-screw extruder. Alternatively, the resin composition is uniformly kneaded in advance using a kneader provided with blades such as a roll, a cam, a kneader, or a banbury mixer, and then is pressed and processed to a predetermined thickness by pressing with a hot plate to produce an unfoamed resin molded product. The unfoamed resin molded article thus obtained is placed in a high-pressure vessel, and a high-pressure inert gas (e.g., carbon dioxide in a supercritical state) is injected to impregnate the unfoamed resin molded article with the inert gas. When the resin is sufficiently impregnated with the inert gas, the pressure is released (usually to atmospheric pressure), and bubble nuclei are generated in the resin. The cell nuclei can be grown directly at room temperature, but in some cases, they can be grown by heating. As a heating method, a known and conventional method such as a water bath, an oil bath, a hot roll, a hot air oven, a far infrared ray, a near infrared ray, a microwave, or the like can be used. After the cells are grown in this manner, the shape is fixed by rapid cooling with cold water or the like, whereby a foam can be obtained. The unfoamed resin molded article to be foamed is not limited to a sheet-like material, and unfoamed resin molded articles of various shapes may be used depending on the application. The unfoamed resin molded article to be foamed may be produced by other molding methods such as injection molding, in addition to extrusion molding and press molding.

An example of producing the foam in a continuous manner is shown below. For example, the foam molding is performed by a kneading and impregnating step of injecting (introducing) a high-pressure gas (particularly an inert gas, and further carbon dioxide) while kneading the resin composition by using an extruder such as a single-screw extruder or a twin-screw extruder, and a molding and pressure-reducing step of sufficiently impregnating the resin composition with the high-pressure gas; in the molding and pressure-reducing step, the resin composition is extruded through a die or the like provided at the tip of the extruder, and molding and foaming are simultaneously performed while releasing the pressure (usually to atmospheric pressure). In the case of foam molding in a continuous manner, a heating step of growing bubbles by heating may be provided as necessary. After the growth of the bubbles in this manner, the shape can be fixed by rapidly cooling with cold water or the like as necessary. The introduction of the high-pressure gas may be performed continuously or discontinuously. In the kneading and impregnating step and the molding and depressurizing step, for example, an extruder or an injection molding machine can be used. As a heating method for growing the bubble nuclei, any appropriate method such as a water bath, an oil bath, a hot roll, a hot air oven, a far infrared ray, a near infrared ray, and a microwave can be exemplified. The shape of the foam may be any suitable shape. Examples of such a shape include: sheet, prism, cylinder, profile, etc.

The amount of the gas to be mixed in the foaming and molding of the resin composition is, for example, preferably 2 to 10 wt%, more preferably 2.5 to 8 wt%, and still more preferably 3 to 6 wt% based on the total amount of the resin composition, from the viewpoint of obtaining a highly foamed foam.

The pressure at the time of impregnating the resin composition with the inert gas may be appropriately selected in consideration of workability and the like. Such a pressure is preferably 6MPa or more (for example, 6MPa to 100MPa), and more preferably 8MPa or more (for example, 8MPa to 50MPa), for example. In view of maintaining the supercritical state of carbon dioxide, the pressure in the case of using carbon dioxide in the supercritical state is preferably 7.4MPa or more. When the pressure is less than 6MPa, the cell growth during foaming becomes remarkable, the cell diameter becomes too large, and a preferable average cell diameter (average cell diameter) may not be obtained. This is because, when the pressure is low, the amount of gas impregnated is relatively small compared to when the pressure is high, the rate of cell nuclei formation decreases, the number of cell nuclei formed decreases, and therefore the amount of gas per 1 cell on average increases rather, and the cell diameter becomes extremely large. In addition, in the pressure region of less than 6MPa, the bubble diameter and the bubble density are greatly changed by only a slight change in the infiltration pressure, and therefore, it is easy to make control of the bubble diameter and the bubble density difficult.

The temperature in the gas impregnation step varies depending on the inert gas used, the kind of the component in the resin composition, and the like, and can be selected from a wide range. In consideration of handling properties, etc., it is preferably 10 to 350 ℃. The impregnation temperature when impregnating the unfoamed molded article with the inert gas is preferably 10 to 250 ℃ and more preferably 40 to 230 ℃ in the case of a batch system. In addition, the impregnation temperature when the molten polymer impregnated with the gas is extruded and simultaneously foamed and molded is preferably 60 to 350 ℃ in the case of a continuous type. When carbon dioxide is used as the inert gas, the temperature at the time of impregnation is preferably 32 ℃ or higher, more preferably 40 ℃ or higher, in order to maintain the supercritical state.

In the pressure reduction step, the pressure reduction rate is preferably 5 to 300 MPa/sec in order to obtain uniform fine bubbles.

The heating temperature in the heating step is preferably 40 to 250 ℃, and more preferably 60 to 250 ℃.

B. Foaming member

Fig. 1 is a schematic sectional view of a foaming member according to an embodiment of the present invention. The foamed member 100 includes a resin foamed layer 10 and a pressure-sensitive adhesive layer 20 disposed on at least one side of the resin foamed layer 10. The resin foam layer 10 is made of the resin foam described above.

The thickness of the pressure-sensitive adhesive layer is preferably 5 to 300. mu.m, more preferably 6 to 200. mu.m, still more preferably 7 to 100. mu.m, and particularly preferably 8 to 50 μm. When the thickness of the pressure-sensitive adhesive layer is within the above range, the foamed member can exhibit excellent impact absorbability.

As the adhesive layer, a layer formed of any appropriate adhesive can be used. Examples of the adhesive constituting the adhesive layer include: rubber-based adhesives (synthetic rubber-based adhesives, natural rubber-based adhesives, etc.), urethane-based adhesives, acrylic-based adhesives, silicone-based adhesives, polyester-based adhesives, polyamide-based adhesives, epoxy-based adhesives, vinyl alkyl ether-based adhesives, fluorine-based adhesives, rubber-based adhesives, and the like. The pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is preferably at least one selected from the group consisting of acrylic pressure-sensitive adhesives, silicone pressure-sensitive adhesives, and rubber pressure-sensitive adhesives. Such a binder may be one type, or two or more types. The adhesive layer may be one layer or two or more layers.

As the adhesive, if classified by the adhesive method, there are, for example: emulsion type adhesives, solvent type adhesives, ultraviolet ray crosslinking type (UV crosslinking type) adhesives, electron beam crosslinking type (EB crosslinking type) adhesives, hot melt type adhesives (hot melt type adhesives), and the like. Such a binder may be one type, or two or more types.

The water vapor permeability of the adhesive layer is preferably 50 (g/(m))²24 hours)) or less, and more preferably 30 (g/(m)²24 hours)) or less, and more preferably 20 (g/(m))²24 hours)) or less, particularly preferably 10 (g/(m)²24 hours)) below. If the water vapor permeability of the adhesive layer is within the above range, the above foam sheet can stabilize the impact absorbability without being affected by moisture. The water vapor permeability can be measured, for example, by a method according to JIS Z0208 under test conditions of 40 ℃ and a relative humidity of 92%.

Any suitable other component may be contained in the adhesive constituting the adhesive layer within a range not impairing the effects of the present invention. Examples of other components include: other polymer components, softening agents, antioxidants, curing agents, plasticizers, fillers, antioxidants, thermal polymerization initiators, photopolymerization initiators, ultraviolet absorbers, light stabilizers, colorants (pigments, dyes, etc.), solvents (organic solvents), surfactants (e.g., ionic surfactants, silicone surfactants, fluorine surfactants, etc.), crosslinking agents (e.g., polyisocyanate-based crosslinking agents, silicone-based crosslinking agents, epoxy-based crosslinking agents, alkyl ether melamine-based crosslinking agents, etc.), and the like. The thermal polymerization initiator and the photopolymerization initiator may be contained in a material for forming the polymer component.

The foamed member may be produced by any suitable method. Examples of the method for producing the foamed member include: a method of manufacturing a laminate by laminating a resin foam layer and an adhesive layer; and a method of producing the pressure-sensitive adhesive layer by laminating a material for forming the pressure-sensitive adhesive layer and a resin foam layer and then forming the pressure-sensitive adhesive layer by a curing reaction or the like.

Examples

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples at all. The test and evaluation methods in examples and the like are as follows. In the case of "part(s)", unless otherwise specified, "part(s) by weight" means "part(s) by weight", and in the case of "%" means "% by weight", unless otherwise specified.

[ evaluation method ]

< apparent Density >

The density (apparent density) of the resin foam was calculated as follows. The resin foam obtained in example/comparative example was punched out into a size of 20mm × 20mm, and as a test piece, the size of the test piece was measured with a caliper, and then, the weight of the test piece was measured by an electronic balance, and calculated by the following formula.

Apparent density (g/cm)³) Weight of test piece/volume of test piece

< 25% compressive load, 50% compressive load >

The measurement was carried out according to the method for measuring the compression hardness of a foam described in JIS K6767. Specifically, the resin foams obtained in examples/comparative examples were cut into 30mm × 30mm pieces, and the pieces were compressed at a compression rate of 10mm/min until the compression rate became 25% or 50%, and the stress (N) at that time was converted into an average area per unit area (1 cm)²) Value of (d) as 25% compressive load (N/cm)²) 50% compressive load (N/cm)²)。

< method for measuring residue of resin foam at 650 >

5mg of the resin foam structure obtained in example/comparative example was charged into a platinum container, and the temperature was raised in a nitrogen atmosphere at a temperature raising rate of 20 ℃/min within a measurement range of 25 ℃ to 680 ℃, and the residue at 650 ℃ was measured using TG/DTA6200 (manufactured by SII Nanotechnology Co.).

< coefficient of variation of average bubble diameter (average pore diameter) and bubble diameter (pore diameter) >

The resin foam was cut along the TD (direction orthogonal to the flow direction) and in the direction perpendicular to the main surface of the resin foam (thickness direction) using a razor, and as a measuring instrument, a digital microscope (trade name "VHX-500", manufactured by Keyence corporation) was used to introduce an enlarged image of the cell portion of the resin foam, and the number average cell diameter (average pore diameter) (μm) was obtained by performing image analysis using analysis software of the same measuring instrument. The number of bubbles in the introduced enlarged image is about 400. Further, a standard deviation was calculated from all the data of the pore diameters, and a variation coefficient was calculated using the following equation.

Coefficient of variation (standard deviation/average bubble diameter)

< aspect ratio of gas bubble >

The aspect ratio of cells of the resin foam obtained in examples/comparative examples was measured by the following method using a digital microscope (trade name "VHX-2000, manufactured by Keyence corporation).

The resin foam is cut along the TD (direction orthogonal to the flow direction) and in the direction (thickness direction) perpendicular to the main surface of the resin foam using a razor, and a predetermined area (3 mm) is observed in a cross-section at a magnification of 100 times using a microscope (for example, "VHX-2000" manufactured by Keyence)²) The length of one bubble in the thickness direction and the length of TD were measured.

The same measurement is performed for all the bubbles present in a given area.

< porosity (porosity) >

The measurement was carried out in an environment at a temperature of 23 ℃ and a humidity of 50%. The resin foams obtained in examples/comparative examples were punched out with a 100mm × 100mm punching die (2-piece processing cutter (trade name "NCA 07", thickness 0.5mm, cutting edge angle 45 °, manufactured by NAKAYAMA Co., Ltd.)) to measure the dimensions of the punched samples. The thickness was measured with an 1/100 micrometer having a measuring terminal diameter (. phi.) of 20 mm. From these values, the volume of the resin foam obtained in examples/comparative examples was calculated. Next, the weight of the resin foam obtained in examples/comparative examples was measured by a balance pan with a minimum scale of 0.01g or more. From these values, the cell content (porosity) of the resin foam obtained in examples/comparative examples was calculated.

< thickness of air bubble wall (air pore wall) >

The resin foam was cut along the TD (direction orthogonal to the flow direction) and in the direction perpendicular to the main surface of the resin foam (thickness direction) using a razor, and as a measuring instrument, a digital microscope (trade name "VHX-500", manufactured by Keyence corporation) was used to introduce an enlarged image of the cell portion of the resin foam, and the thickness (μm) of the cell wall (pore wall) was obtained by performing image analysis using analysis software of the same measuring instrument. The number of bubbles in the introduced enlarged image is about 400.

< non-foaming bending stress >

A resin molded article a in a non-foamed state was obtained by pressurizing the resin foam for 5 minutes at a temperature of (melting point +70 ℃) and a pressure of 15MPa using a vacuum pressure molding machine (IVM-70: Seawa Kaisha).

A sample obtained by cutting out a resin molded article a having a width of 6mm and a length of 50mm was placed on a 3-point bending jig having a distance of 25mm between fulcrums, and a press-in test (trade name "AG-Xplus" manufactured by Shimadzu corporation) was carried out at a press-in speed of 0.5mm/min in an environment of 23 ℃ C.. times.50% RH, and a load (g) when the sample was pressed in a 5mm pressure was defined as a non-foaming bending stress.

< elastic strain energy >

The compression ratio (%) and compression rebound force (kPa) of the resin foam were measured in accordance with one of compression tests of JIS K6767, and the area of a region having a compression ratio of 0% to 10% out of the area surrounded by the compression SS curve having a compression ratio of x axis and a compression rebound force of y axis and the x axis was calculated as elastic strain energy.

< recovery rate of thickness >

For the resin foam, 1000g/cm was applied to the resin foam²The pressure was released by holding the resin foam in the state of load for 120 seconds, and the thickness of the resin foam 0.5 second after the release of the compression (the thickness 0.5 second after the release of the compression) was measured. The thickness recovery rate was determined from the "thickness 0.5 seconds after the release of the compression" and the thickness of the resin foam before the application of the load (initial thickness) by the following equation.

< impact absorption Rate >

A resin foam, a double-sided tape (model: No.5603W, manufactured by Nindon electric), and a PET film (model: DIAFOIL MRF75, manufactured by Mitsubishi resin) were disposed in this order on the impact force sensor to form a test body. 66g of iron balls were dropped from a height of 50cm above the PET film to the test piece, and the impact force F1 was measured.

The impact absorption (%) was calculated from F1, F0 and by the formula (F0-F1)/F0X 100.

< horizontal combustion distance >

The measurement was performed by the flame retardant test method for the foam described in UL 94.

The flame retardancy was evaluated as remarkably excellent when the horizontal distance was less than 60mm (X. in the table), good when the horizontal distance was 60mm or more and 1 to less than 150mm (O. in the table), and defective when the horizontal distance was 150mm or more (X in the table).

[ example 1]

65 parts by weight of polypropylene (melt flow rate (MFR) (230 ℃ C.): 0.40g/10min), 35 parts by weight of a polyolefin elastomer (melt flow rate (MFR): 6g/10min, JIS A hardness: 79 ℃ C.), 80 parts by weight of magnesium hydroxide (trade name "KISUMA 5P" manufactured by KAPPO CHEMICAL INDUSTRY), 10 parts by weight of carbon (trade name "Asahi # 35" manufactured by Asahi carbon Co., Ltd.), and 1 part by weight of monoglyceride stearate were kneaded at a temperature of 200 ℃ using a twin-screw kneader manufactured by Japan Steel Works (JSW) of Japan, extruded in the form of strands, water-cooled, and molded into pellets. The pellets were charged into a single-screw extruder made by Nippon Steel works, and carbon dioxide gas was injected at a pressure of 13MPa (12 MPa after injection) in an atmosphere of 220 ℃. Carbon dioxide gas was injected in a proportion of 4.5 parts by weight with respect to 100 parts by weight of the resin. After carbon dioxide gas was sufficiently saturated, the mixture was cooled to a temperature suitable for foaming, and then extruded from a die to obtain a sheet-like molded article. The sheet-like molded article was flaked by a slicer to obtain a resin foam a having a thickness of 0.3 mm.

Further, the resin foam a was passed through a gap between a pair of rolls (a gap between the rolls) in which one roll was heated to 200 ℃ to obtain a resin foam a having a thickness of 0.1 mm. The gap (clearance) between the rolls was set so that the resin foam A having a thickness of 0.1mm could be obtained.

The obtained resin foam a was subjected to the above evaluation, and the results are shown in table 1.

[ example 2 ]

65 parts by weight of polypropylene (melt flow rate (MFR) (230 ℃ C.): 0.40g/10min), 35 parts by weight of a polyolefin elastomer (melt flow rate (MFR): 6g/10min, JIS A hardness: 79 ℃ C.), 100 parts by weight of magnesium hydroxide (trade name "KISUMA 5P" manufactured by KAPPO CHEMICAL INDUSTRY), 10 parts by weight of carbon (trade name "Asahi # 35" manufactured by Asahi carbon Co., Ltd.), and 1 part by weight of monoglyceride stearate were kneaded at a temperature of 200 ℃ using a twin-screw kneader manufactured by Japan Steel Works (JSW) of Japan, extruded in the form of strands, water-cooled, and molded into pellets. The pellets were charged into a single-screw extruder made by Nippon Steel works, and carbon dioxide gas was injected at a pressure of 13MPa (12 MPa after injection) in an atmosphere of 220 ℃. Carbon dioxide gas was injected in a proportion of 3.5 parts by weight with respect to 100 parts by weight of the resin. After carbon dioxide gas was sufficiently saturated, the mixture was cooled to a temperature suitable for foaming, and then extruded from a die to obtain a sheet-like molded article. The sheet-like molded article was flaked by a slicer to obtain a resin foam b having a thickness of 0.3 mm.

Further, the resin foam B was passed through a gap between a pair of rolls (gap between rolls) in which one roll was heated to 200 ℃ to obtain a resin foam B having a thickness of 0.1 mm. The gap (clearance) between the rolls was set so that the resin foam B having a thickness of 0.1mm could be obtained.

The obtained resin foam B was subjected to the above evaluation, and the results are shown in table 1.

[ example 3 ]

65 parts by weight of polypropylene (melt flow rate (MFR) (230 ℃ C.): 0.40g/10min), 35 parts by weight of a polyolefin elastomer (melt flow rate (MFR): 6g/10min, JIS A hardness: 79 ℃ C.), 120 parts by weight of magnesium hydroxide (trade name "KISUMA 5P" available from Kyowa chemical industries), 10 parts by weight of carbon (trade name "Asahi # 35" available from Asahi carbon Co., Ltd.), and 1 part by weight of monoglyceride stearate were kneaded at a temperature of 200 ℃ using a twin-screw kneader manufactured by JSW Kagaku Kogyo (JSW), extruded in a strand form, water-cooled and molded into pellets. The pellets were charged into a single-screw extruder made by Nippon Steel works, and carbon dioxide gas was injected at a pressure of 13MPa (12 MPa after injection) in an atmosphere of 220 ℃. Carbon dioxide gas was injected in a proportion of 3.0 parts by weight with respect to 100 parts by weight of the resin. After carbon dioxide gas was sufficiently saturated, the mixture was cooled to a temperature suitable for foaming, and then extruded from a die to obtain a sheet-like molded article. The molded sheet was flaked by a slicer to obtain a resin foam c having a thickness of 0.3 mm.

Further, the resin foam C was passed through a gap between a pair of rolls (a gap between the rolls) in which one roll was heated to 200 ℃, to obtain a resin foam C having a thickness of 0.1 mm. The gap (clearance) between the rolls was set so that the resin foam C having a thickness of 0.1mm could be obtained.

The obtained resin foam C was subjected to the above evaluation, and the results are shown in table 1.

[ example 4 ]

15 parts by weight of polypropylene (melt flow rate (MFR) (230 ℃ C.): 0.40g/10min), 15 parts by weight of polypropylene (melt flow rate (MFR) (230 ℃ C.): 1.1g/10min), 75 parts by weight of polyolefin elastomer (melt flow rate (MFR): 6g/10min, JIS A hardness: 79 ℃ C.), 80 parts by weight of magnesium hydroxide (trade name "KISUMA 5P" manufactured by KAPPHI CHEMICAL INDUSTRIAL Co., Ltd.), 10 parts by weight of carbon (trade name "Asahi # 35" manufactured by Asahi carbon Co., Ltd.) and 1 part by weight of glycerol monostearate were kneaded at a temperature of 200 ℃ using a twin-screw kneader manufactured by Japan Steel Works (JSW) of Japan, extruded in the form of pellets, water-cooled and molded into pellets. The pellets were charged into a single-screw extruder made by Nippon Steel works, and carbon dioxide gas was injected at a pressure of 13MPa (12 MPa after injection) in an atmosphere of 220 ℃. Carbon dioxide gas was injected in a proportion of 2.8 parts by weight with respect to 100 parts by weight of the resin. After carbon dioxide gas was sufficiently saturated, the mixture was cooled to a temperature suitable for foaming, and then extruded from a die to obtain a sheet-like molded article. The sheet-like molded article was flaked by a slicer to obtain a resin foam d having a thickness of 0.4 mm.

Further, the resin foam D was passed through a gap between a pair of rolls (gap between rolls) in which one roll was heated to 200 ℃ to obtain a resin foam D having a thickness of 0.1 mm. The gap (clearance) between the rolls was set so that the resin foam D having a thickness of 0.1mm could be obtained.

The obtained resin foam D was subjected to the above evaluation, and the results are shown in table 1.

[ example 5 ]

15 parts by weight of polypropylene (melt flow rate (MFR) (230 ℃ C.): 0.40g/10min), 15 parts by weight of polypropylene (melt flow rate (MFR) (230 ℃ C.): 1.1g/10min), 75 parts by weight of polyolefin elastomer (melt flow rate (MFR): 6g/10min, JIS A hardness: 79 ℃ C.), 60 parts by weight of magnesium hydroxide (trade name "KISUMA 5P" manufactured by KAPPHI CHEMICAL INDUSTRIAL Co., Ltd.), 10 parts by weight of carbon (trade name "Asahi # 35" manufactured by Asahi carbon Co., Ltd.) and 1 part by weight of glycerol monostearate were kneaded at a temperature of 200 ℃ using a twin-screw kneader manufactured by Japan Steel Works (JSW) of Japan, extruded in the form of pellets, water-cooled and molded into pellets. The pellets were charged into a single screw extruder made by Japan Steel making, and carbon dioxide gas was injected at a pressure of 13MPa (12 MPa after injection) in an atmosphere of 220 ℃. Carbon dioxide gas was injected in a proportion of 2.6 parts by weight with respect to 100 parts by weight of the resin. After carbon dioxide gas was sufficiently saturated, the mixture was cooled to a temperature suitable for foaming, and then extruded from a die to obtain a sheet-like molded article. The sheet-like molded article was flaked by a slicer to obtain a resin foam e having a thickness of 0.4 mm.

Further, the resin foam E was passed through a gap between a pair of rolls (a gap between the rolls) in which one roll was heated to 200 ℃, to obtain a resin foam E having a thickness of 0.1 mm. The gap (clearance) between the rolls was set so that the resin foam E having a thickness of 0.1mm could be obtained.

The obtained resin foam E was subjected to the above evaluation, and the results are shown in table 1.

[ comparative example 1]

16.5 parts by weight of polypropylene (melt flow rate (MFR) (230 ℃ C.): 0.40g/10min), 16.5 parts by weight of polypropylene (melt flow rate (MFR) (230 ℃ C.): 1.1g/10min), 67 parts by weight of a polyolefin elastomer (melt flow rate (MFR): 6g/10min, JIS A hardness: 79 ℃ C.), 40 parts by weight of magnesium hydroxide (trade name "KISUMA 5P", manufactured by KAPPI chemical industries), 10 parts by weight of carbon (trade name "Asahi # 35", manufactured by Asahi carbon Co., Ltd.) and 1 part by weight of monoglyceride stearate were kneaded at a temperature of 200 ℃ using a twin-screw kneader manufactured by Japan Steel Works (JSW) of Japan, extruded in the form of strands, water-cooled and molded into pellets. The pellets were charged into a single-screw extruder made by Nippon Steel works, and carbon dioxide gas was injected at a pressure of 13MPa (12 MPa after injection) in an atmosphere of 220 ℃. Carbon dioxide gas was injected in a proportion of 3 parts by weight with respect to 100 parts by weight of the resin. After carbon dioxide gas was sufficiently saturated, the mixture was cooled to a temperature suitable for foaming, and then extruded from a die to obtain a sheet-like molded article. The sheet-like molded article was flaked by a slicer to obtain a resin foam f having a thickness of 0.4 mm.

Further, the resin foam F was passed through a gap between a pair of rolls (gap between rolls) in which one roll was heated to 200 ℃ to obtain a resin foam F having a thickness of 0.1 mm. The gap (clearance) between the rolls was set so that a resin foam F having a thickness of 0.1mm could be obtained.

The resin foam F obtained was subjected to the above evaluation, and the results are shown in table 1.

[ comparative example 2 ]

45 parts by weight of polypropylene (melt flow rate (MFR) (230 ℃ C.): 0.40g/10min), 55 parts by weight of a polyolefin elastomer (melt flow rate (MFR): 6g/10min, JIS A hardness: 79 ℃ C.), 10 parts by weight of magnesium hydroxide (trade name "KISUMA 5P" manufactured by KAPPON CHEMICAL INDUSTRY), 10 parts by weight of carbon (trade name "Asahi # 35" manufactured by Asahi carbon Co., Ltd.), and 1 part by weight of monoglyceride stearate were kneaded at a temperature of 200 ℃ using a twin-screw kneader manufactured by Japan Steel Works (JSW) of Japan, extruded in the form of strands, water-cooled, and molded into pellets. The pellets were charged into a single screw extruder made by Japan Steel making, and carbon dioxide gas was injected at a pressure of 13MPa (12 MPa after injection) in an atmosphere of 220 ℃. Carbon dioxide gas was injected in a proportion of 5.5 parts by weight with respect to 100 parts by weight of the resin. After carbon dioxide gas was sufficiently saturated, the mixture was cooled to a temperature suitable for foaming, and then extruded from a die to obtain a sheet-like molded article. The molded sheet was flaked by a slicer to obtain a resin foam g having a thickness of 0.3 mm.

Further, the resin foam G was passed through a gap between a pair of rolls (gap between rolls) in which one roll was heated to 200 ℃ to obtain a resin foam G having a thickness of 0.1 mm. The gap (clearance) between the rolls was set so that a resin foam G having a thickness of 0.1mm could be obtained.

The obtained resin foam G was subjected to the above evaluation, and the results are shown in table 1.

[ comparative example 3 ]

19 parts by weight of polypropylene (melt flow rate (MFR) (230 ℃ C.): 0.40g/10min), 19 parts by weight of polypropylene (melt flow rate (MFR) (230 ℃ C.): 1.1g/10min), 67 parts by weight of polyolefin elastomer (melt flow rate (MFR): 6g/10min, JIS A hardness: 79 ℃ C.), 80 parts by weight of magnesium hydroxide (trade name "KISUMA 5P" manufactured by KAPPHI CHEMICAL INDUSTRIAL Co., Ltd.), 10 parts by weight of carbon (trade name "Asahi # 35" manufactured by Asahi carbon Co., Ltd.) and 1 part by weight of monoglyceride stearate were kneaded at a temperature of 200 ℃ and then extruded in the form of pellets, water-cooled and molded into pellets. The pellets were charged into a single-screw extruder made by Nippon Steel works, and carbon dioxide gas was injected at a pressure of 13MPa (12 MPa after injection) in an atmosphere of 220 ℃. Carbon dioxide gas was injected in a proportion of 2.5 parts by weight relative to 100 parts by weight of the resin. After carbon dioxide gas was sufficiently saturated, the mixture was cooled to a temperature suitable for foaming, and then extruded from a die to obtain a sheet-like resin foam h. Further, using a microtome, a resin foam H having a thickness of 0.3mm was obtained.

The obtained resin foam H was subjected to the above evaluation, and the results are shown in table 1.

[ Table 1]

	Example 1	Example 2	Example 3	Example 4	Example 5	Comparative example 1	Comparative example 2	Comparative example 3
									Apparent density [ g/cm ]³]	0.11	0.14	0.14	0.12	0.14	0.12	0.1	0.12
25% compressive load [ N/cm²]	5.5	7.5	4	3.5	3.3	3.5	2	2
									R: the foam residue at 650 ℃ [ wt.%]	34	36	45	34	30	18	14	34
Diameter of air bubble [ mu ] m]	40	70	80	100	95	80	75	90
									Coefficient of variation of bubble diameter-]	0.35	0.32	0.3	0.4	0.42	0.45	0.4	0.4
Aspect ratio of the bubbles	1.6	1.9	2.8	3.2	3.1	2.8	1.8	1.2
									Percentage of bubbles [% ]]	90	88	85	88	86	88	90	88
Thickness of pore wall [ μm ]]	2	2.5	2.2	2.6	2.6	1	1	3.2
									50% compressive load [ N/cm²]	12	20	15	10	10	9	2	8
Non-foaming bending stress [ MPa ]]	13	13.5	10.2	9.4	6.5	9.6	3.5	7.5
									Elastic strain energy [ kPa ]]	180	200	90	80	65	50	8	10
Thickness recovery [% ]]	84	85	88	91	92	87	70	85
									Impact absorption [% ]]	40	45	40	30	30	30	20	24
Horizontal burning distance [ mm ]]	80	55	40	85	130	150＞	150＞	80
									Flame retardancy	○	◎	◎	○	○	×	×	○

Industrial applicability

The resin foam of the present invention can be suitably used as a cushioning material for electronic devices, for example.

Claims

1. A resin foam having an apparent density of 0.02g/cm³～0.5g/cm³25% compressive load of 3N/cm²The above residue R at 650 ℃ is 20% by weight or more and has a bubble structure.

2. The resin foam according to claim 1, wherein,

the resin foam has an elastic strain energy of 10kPa or more when compressed.

3. The resin foam according to claim 1 or 2, wherein the non-foaming bending stress is 5MPa or more.

4. The resin foam according to any one of claims 1 to 3, which has a thickness recovery rate of 70% or more.

5. The resin foam according to any one of claims 1 to 4, wherein,

the resin foam has cells having an aspect ratio of 1.5 or more.

6. The resin foam according to any one of claims 1 to 5, which has an average cell diameter of 10 to 200 μm.

7. The resin foam according to any one of claims 1 to 6, which has a cell ratio of 30% or more.

8. The resin foam according to any one of claims 1 to 7, wherein the coefficient of variation of the cell diameter is 0.5 or less.

9. The resin foam according to any one of claims 1 to 8, wherein the thickness of the cell wall is 0.1 to 10 μm.

10. The resin foam according to any one of claims 1 to 9, which comprises a polyolefin resin.

11. The resin foam according to claim 10, wherein,

the polyolefin-based resin is a mixture of polyolefin other than the polyolefin-based elastomer and the polyolefin-based elastomer.

12. The resin foam according to any one of claims 1 to 11,

the resin foam has a heat-fusible layer on one or both surfaces thereof.

13. A foamed member having a resin foamed layer and an adhesive layer disposed on at least one side of the resin foamed layer,

the resin foam layer is the resin foam according to any one of claims 1 to 12.