WO2018181982A1 - 架橋樹脂発泡シート、その製造方法、及び粘着テープ - Google Patents

架橋樹脂発泡シート、その製造方法、及び粘着テープ Download PDF

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Publication number
WO2018181982A1
WO2018181982A1 PCT/JP2018/013834 JP2018013834W WO2018181982A1 WO 2018181982 A1 WO2018181982 A1 WO 2018181982A1 JP 2018013834 W JP2018013834 W JP 2018013834W WO 2018181982 A1 WO2018181982 A1 WO 2018181982A1
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Prior art keywords
resin
foam sheet
sheet
sheet according
resin foam
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PCT/JP2018/013834
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English (en)
French (fr)
Japanese (ja)
Inventor
麻美 永井
哲史 濱田
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積水化学工業株式会社
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Application filed by 積水化学工業株式会社 filed Critical 積水化学工業株式会社
Priority to CN202211555302.6A priority Critical patent/CN115819827A/zh
Priority to KR1020197028006A priority patent/KR20190129886A/ko
Priority to CN201880018702.9A priority patent/CN110446747B/zh
Priority to JP2018519892A priority patent/JP6901476B2/ja
Publication of WO2018181982A1 publication Critical patent/WO2018181982A1/ja

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/04—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent
    • C08J9/06—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof using blowing gases generated by a previously added blowing agent by a chemical blowing agent
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L23/04—Homopolymers or copolymers of ethene
    • C08L23/06—Polyethene
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
    • C09J7/22—Plastics; Metallised plastics
    • C09J7/24—Plastics; Metallised plastics based on macromolecular compounds obtained by reactions involving only carbon-to-carbon unsaturated bonds
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J7/00—Adhesives in the form of films or foils
    • C09J7/20—Adhesives in the form of films or foils characterised by their carriers
    • C09J7/22—Plastics; Metallised plastics
    • C09J7/26—Porous or cellular plastics
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2205/00—Foams characterised by their properties
    • C08J2205/04—Foams characterised by their properties characterised by the foam pores
    • C08J2205/052—Closed cells, i.e. more than 50% of the pores are closed
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
    • C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
    • C08J2323/04—Homopolymers or copolymers of ethene
    • C08J2323/06—Polyethene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2207/00—Properties characterising the ingredient of the composition
    • C08L2207/06—Properties of polyethylene
    • C08L2207/066—LDPE (radical process)
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2314/00—Polymer mixtures characterised by way of preparation
    • C08L2314/06—Metallocene or single site catalysts

Definitions

  • the present invention relates to a crosslinked resin foam sheet, a method for producing the same, and an adhesive tape including the crosslinked resin foam sheet.
  • sealing materials or shock absorbing materials made of foamed sheets have been used.
  • These sealing materials or impact absorbing materials may be used as an adhesive tape using a foam sheet as a base material.
  • the display device in the electronic apparatus generally has a structure in which a protective panel is installed on a display panel such as an LCD. However, in order to bond the protective panel to a frame portion outside the display panel, foaming is performed. An adhesive tape having a sheet as a base material is used.
  • a foam sheet used inside an electronic device a crosslinked polyolefin resin foam sheet obtained by foaming and crosslinking a foamable polyolefin resin sheet containing a pyrolytic foaming agent is known (for example, Patent Document 1). reference).
  • the foamed sheet is required to prevent excessive flexibility even when the width is reduced, and to improve durability such as impact resistance.
  • the present invention has been made in view of the above circumstances, for example, to provide a resin foam sheet that can be prevented from becoming too flexible even when the width is narrowed and that is excellent in impact resistance. To do.
  • the present invention provides the following [1] to [12].
  • [1] A cross-linked resin foam sheet having closed cells, and the reduction rate of the compressive strength (C 1 ) measured at a sample width of 1 mm with respect to the compressive strength (C 20 ) measured at a sample width of 20 mm is 60% or less.
  • the cross-linked resin foam sheet according to the present invention (hereinafter also simply referred to as “foam sheet”) is a foam sheet having closed cells, and measured at a sample width of 1 mm with respect to the compressive strength (C 20 ) measured at a sample width of 20 mm.
  • the decrease rate of the compressed strength (C 1 ) is 60% or less.
  • the rate of decrease in compressive strength is calculated from (C 20 -C 1 ) / C 20 .
  • the foamed sheet of the present invention can maintain a high compressive strength even if the sample width is narrowed by reducing the rate of decrease in compressive strength.
  • the foamed sheet is prevented from becoming too flexible, and sticking failure or the like that occurs when sticking an adhesive tape using the foamed sheet as a base material is less likely to occur. Further, even when the foamed sheet has a narrow width, the mechanical strength such as impact resistance is maintained high, and the foamed sheet can be suitably used as an impact absorbing material in a miniaturized electronic device.
  • the rate of decrease in the compression strength is preferably 55% or less, more preferably 40% or less, and even more preferably 30% or less. preferable. Further, the lowering rate of the compressive strength is preferably as low as possible, but is practically 5% or more.
  • either the reduction rate when measuring the 10% compressive strength or the reduction rate when measuring the 25% compressive strength may be within the above range, but both are within the above range. It is preferable that When any reduction rate is within the above range, various performances such as sticking property and impact resistance are improved under various use conditions.
  • the measuring method of 10% and 25% compressive strength is as showing in the Example mentioned later.
  • the foam sheet of the present invention has closed cells. Having closed cells means that the ratio of closed cells to all bubbles (referred to as “closed cell rate”) is 70% or more.
  • the closed cell ratio is preferably 75% or more, more preferably 90% or more.
  • the closed cell ratio can be determined according to ASTM D2856 (1998). Commercially available measuring instruments include a dry automatic densitometer Accupic 1330 and the like.
  • the closed cell ratio is measured in the following manner.
  • a test piece having a flat square shape with a side of 5 cm and a constant thickness is cut out from the foam sheet.
  • the thickness of the test piece is measured, the apparent volume V 1 of the test piece is calculated, and the weight W 1 of the test piece is measured.
  • the apparent volume V 2 occupied by the bubbles is calculated based on the following formula.
  • the density of the resin constituting the test piece is 1 g / cm 3 .
  • Apparent volume occupied by bubbles V 2 V 1 ⁇ W 1
  • the test piece is submerged in distilled water at 23 ° C. to a depth of 100 mm from the water surface, and a pressure of 15 kPa is applied to the test piece over 3 minutes.
  • Open cell ratio F 1 (%) 100 ⁇ (W 2 ⁇ W 1 ) / V 2
  • Closed cell ratio F 2 (%) 100 ⁇ F 1
  • the foamed sheet preferably has an average cell diameter in the MD and TD directions of preferably 100 ⁇ m or less, more preferably 80 ⁇ m or less, and even more preferably 70 ⁇ m or less. Bubbles having such an average bubble diameter are generally called fine bubbles. Since the foam sheet has fine bubbles, even when the sheet width is narrowed, a large number of closed cells exist between the narrow widths. At the end face of the foam sheet, bubbles are cut and behave like open cells, causing a decrease in compressive strength. However, the bubbles to be cut are fine bubbles and there are many closed cells in a narrow width. By doing so, it is possible to minimize a decrease in compressive strength due to air bubbles at the sheet end face.
  • each of the average bubble diameters of MD and TD is preferably 10 ⁇ m or more, more preferably 20 ⁇ m or more, and further preferably 30 ⁇ m or more from the viewpoint of ease of production.
  • an average bubble diameter means what was measured in the following way.
  • a foam sheet cut into a 50 mm square was prepared as a foam sample for measurement. This was immersed in liquid nitrogen for 1 minute and then cut with a razor blade in the thickness direction along the MD and TD directions. This cross-section is taken with a digital microscope (Keyence Co., Ltd. “VHX-900”), and a 200-times magnified photograph is taken, and all the bubbles present on the cut surface for a length of 2 mm in each of the MD direction and the TD direction are observed. The bubble diameter was measured and the operation was repeated 5 times. And the average value of all the bubbles was made into the average bubble diameter of MD direction and each TD direction.
  • the MD direction means Machine direction and coincides with the extrusion direction
  • the TD direction means Transverse direction, which is a direction orthogonal to the MD direction and parallel to the sheet surface of the foam sheet.
  • the ZD direction is the thickness direction of the foam and is a direction perpendicular to both the MD direction and the TD direction.
  • the fine bubbles have a small variation in bubble diameter in the MD and TD directions.
  • the standard deviation of the bubble diameters in the MD and TD directions is preferably 60 ⁇ m or less, and more preferably 40 ⁇ m or less.
  • the standard deviation of the bubble diameter is preferably as low as possible and is preferably 0 ⁇ m, but is preferably 1 ⁇ m or more from a practical viewpoint.
  • the standard deviation of the bubble diameter of MD and TD direction is calculated based on each bubble diameter measured in order to obtain
  • the foam sheet is a cross-linked foam, and the degree of cross-linking is preferably 30% by mass or more.
  • the degree of cross-linking is more preferably 35 to 65% by mass, and further preferably 40 to 49% by mass.
  • the thickness of the foam sheet is preferably 0.03 to 0.5 mm. When the thickness is 0.03 mm or more, it becomes easy to ensure the impact resistance and flexibility of the foam sheet. Further, when the thickness is 0.5 mm or less, it is possible to reduce the thickness, and it can be suitably used for a miniaturized electronic device. From these viewpoints, the thickness of the resin foam sheet is more preferably 0.08 to 0.40 mm, and further preferably 0.10 to 0.25 mm.
  • the foamed sheet preferably has a narrow width, and specifically, is preferably processed into a thin line shape. For example, the foam sheet may be used with a width of 5 mm or less, preferably 3 mm or less, more preferably 1 mm or less.
  • the width of the resin foam sheet is narrowed, it can be suitably used inside a miniaturized electronic device. Moreover, even if the width
  • variety of a foamed sheet is not specifically limited, For example, a 0.1 mm or more thing may be sufficient and a 0.2 mm or more thing may be sufficient.
  • the planar shape of the foam sheet is not particularly limited, but may be an elongated rectangular shape, a frame shape, an L shape, a U shape, or the like. However, in addition to these shapes, any other shapes such as a normal quadrangle and a circle may be used.
  • the foaming ratio of the foamed sheet is preferably 1.2 to 4.0 cm 3 / g.
  • the expansion ratio is more preferably 1.3 ⁇ 3.5cm 3 / g, more preferably 2.0 ⁇ 3.0cm 3 / g.
  • the density of the foamed sheet is obtained according to JIS K7222, and the reciprocal thereof is taken as the foaming ratio.
  • the 10% compressive strength (C 1 ) of the foamed sheet with a sample width of 1 mm is preferably 30 to 600 kPa, more preferably 40 to 350 kPa, and even more preferably 100 to 200 kPa.
  • the 25% compressive strength (C 1 ) of the foamed sheet with a sample width of 1 mm is preferably 150 to 1500 kPa, more preferably 250 to 1400 kPa, and further preferably 270 to 600 kPa.
  • Polyolefin resin Various resins may be used as the resin used for the resin foam sheet, and among them, it is preferable to use a polyolefin resin.
  • the polyolefin resin include a polyethylene resin, a polypropylene resin, an ethylene-vinyl acetate copolymer, or a mixture thereof.
  • a polyethylene resin is preferable.
  • the polyethylene resin include a polyethylene resin polymerized with a polymerization catalyst such as a Ziegler-Natta compound, a metallocene compound, and a chromium oxide compound.
  • a polyethylene resin polymerized with a polymerization catalyst of a metallocene compound is used.
  • the polyethylene resin is preferably linear low density polyethylene.
  • linear low density polyethylene By using linear low density polyethylene, flexibility can be imparted to the foamed sheet and the resin foamed sheet can be made thinner.
  • the linear low-density polyethylene is more preferably obtained using a polymerization catalyst such as a metallocene compound.
  • the linear low density polyethylene is obtained by copolymerizing ethylene (for example, 75% by mass or more, preferably 90% by mass or more with respect to the total amount of monomers) and, if necessary, a small amount of ⁇ -olefin. More preferred is linear low density polyethylene.
  • ⁇ -olefin examples include propylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, and 1-octene. Of these, ⁇ -olefins having 4 to 10 carbon atoms are preferred.
  • Polyethylene resin for example the density of the above-mentioned linear low density polyethylene is preferably 0.870 ⁇ 0.910g / cm 3, more preferably 0.875 ⁇ 0.907g / cm 3, 0.880 ⁇ 0.905g / Cm 3 is more preferable.
  • the polyethylene resin a plurality of polyethylene resins can be used, and a polyethylene resin outside the above-described density range may be added.
  • metallocene compound examples include compounds such as a bis (cyclopentadienyl) metal complex having a structure in which a transition metal is sandwiched between ⁇ -electron unsaturated compounds. More specifically, tetravalent transition metals such as titanium, zirconium, nickel, palladium, hafnium, and platinum have one or more cyclopentadienyl rings or their analogs as ligands (ligands). Can be mentioned. Such metallocene compounds have uniform active site properties and each active site has the same activity.
  • a polymer synthesized using a metallocene compound has high uniformity in molecular weight, molecular weight distribution, composition, composition distribution, etc., so when a sheet containing a polymer synthesized using a metallocene compound is crosslinked, the crosslinking is uniform. Proceed to. Since the uniformly cross-linked sheet is uniformly foamed, it is easy to reduce the variation in the bubble diameter as described above. Moreover, since it can extend
  • Examples of the ligand include a cyclopentadienyl ring and an indenyl ring. These cyclic compounds may be substituted with a hydrocarbon group, a substituted hydrocarbon group or a hydrocarbon-substituted metalloid group.
  • Examples of the hydrocarbon group include a methyl group, an ethyl group, various propyl groups, various butyl groups, various amyl groups, various hexyl groups, 2-ethylhexyl groups, various heptyl groups, various octyl groups, various nonyl groups, and various decyl groups. , Various cetyl groups, phenyl groups and the like.
  • the “various” means various isomers including n-, sec-, tert-, and iso-. Moreover, what polymerized the cyclic compound as an oligomer may be used as a ligand. In addition to ⁇ -electron unsaturated compounds, monovalent anion ligands such as chlorine and bromine or divalent anion chelate ligands, hydrocarbons, alkoxides, arylamides, aryloxides, amides, arylamides, phosphides, aryls Phosphide or the like may be used.
  • monovalent anion ligands such as chlorine and bromine or divalent anion chelate ligands, hydrocarbons, alkoxides, arylamides, aryloxides, amides, arylamides, phosphides, aryls Phosphide or the like may be used.
  • metallocene compounds containing tetravalent transition metals and ligands include, for example, cyclopentadienyl titanium tris (dimethylamide), methylcyclopentadienyl titanium tris (dimethylamide), bis (cyclopentadienyl) titanium dichloride, dimethyl And silyltetramethylcyclopentadienyl-t-butylamidozirconium dichloride.
  • the metallocene compound exhibits an action as a catalyst in the polymerization of various olefins by combining with a specific cocatalyst (co-catalyst).
  • cocatalyst include methylaluminoxane (MAO) and boron compounds.
  • the proportion of the cocatalyst used with respect to the metallocene compound is preferably 100,000 to 1,000,000 mole times, more preferably 50 to 5,000 mole times.
  • the above linear low density polyethylene may be used alone, or may be used in combination with other polyolefin resins.
  • the ratio of the other polyolefin resin to the linear low density polyethylene (100% by mass) is preferably 40% by mass or less, more preferably 30% by mass or less, and further preferably 20% by mass or less. preferable.
  • Examples of the ethylene-vinyl acetate copolymer (EVA) used as the polyolefin resin include an ethylene-vinyl acetate copolymer containing 50% by mass or more of ethylene.
  • EVA ethylene-vinyl acetate copolymer
  • the mass ratio (EVA / PE) is preferably 10/90 to 90/10, 80 to 80/20 is more preferable, and 50/50 to 80/20 is even more preferable.
  • Examples of the polypropylene resin include polypropylene and a propylene- ⁇ -olefin copolymer containing 50% by mass or more of propylene.
  • ⁇ -olefin constituting the propylene- ⁇ -olefin copolymer include ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-heptene, 1- Among these, ⁇ -olefins having 6 to 12 carbon atoms are preferable.
  • the resin contained in the foam sheet may be a polyolefin resin alone or may contain a resin other than the polyolefin resin.
  • the ratio of the polyolefin resin to the total amount of the resin is preferably 60% by mass or more, more preferably 70% by mass or more, and still more preferably 80% by mass or more.
  • the resin other than the polyolefin resin used for the foamed sheet include various elastomers such as a styrene thermoplastic elastomer, an ethylene propylene thermoplastic elastomer such as EPDM, and a rubber component.
  • the foam sheet of the present invention is preferably formed by foaming a foamable composition containing the above resin and a pyrolytic foaming agent.
  • a thermal decomposition type foaming agent it is preferable to use a thing with a particle size of less than 15 micrometers. By using a particle having a particle size of less than 15 ⁇ m, it becomes easy to reduce the bubble diameter of the foamed sheet and the variation in the bubble diameter in combination with the relatively high degree of crosslinking as described above.
  • the particle size of the pyrolytic foaming agent is preferably 2 to 14 ⁇ m, more preferably 5 to 13 ⁇ m.
  • the variation in the particle diameter of the foaming agent is preferably small in order to suppress the variation in the bubble diameter.
  • the particle size of the pyrolytic foaming agent is a value measured by a laser diffraction method and means a particle size (D50) corresponding to a cumulative frequency of 50%.
  • Organic foaming agents include azodicarbonamide, azodicarboxylic acid metal salts (such as barium azodicarboxylate), azo compounds such as azobisisobutyronitrile, nitroso compounds such as N, N′-dinitrosopentamethylenetetramine, And hydrazine derivatives such as hydrazodicarbonamide, 4,4′-oxybis (benzenesulfonylhydrazide) and toluenesulfonylhydrazide, and semicarbazide compounds such as toluenesulfonyl semicarbazide.
  • azodicarbonamide azodicarboxylic acid metal salts (such as barium azodicarboxylate)
  • azo compounds such as azobisisobutyronitrile
  • nitroso compounds such as N, N′-dinitrosopentamethylenetetramine
  • hydrazine derivatives such as hydrazodicarbonamide, 4,4′
  • the inorganic foaming agent examples include ammonium acid, sodium carbonate, ammonium hydrogen carbonate, sodium hydrogen carbonate, ammonium nitrite, sodium borohydride, anhydrous monosodium citrate, and the like.
  • an azo compound is preferable and azodicarbonamide is particularly preferable from the viewpoint of obtaining fine bubbles and from the viewpoints of economy and safety.
  • These pyrolytic foaming agents can be used alone or in combination of two or more.
  • the amount of the thermally decomposable foaming agent in the foamable composition is preferably 1 to 10 parts by weight, more preferably 1.5 to 5 parts by weight, and further preferably 2 to 4 parts by weight with respect to 100 parts by weight of the resin. It is.
  • a foamable composition contains a cell nucleus regulator in addition to the said resin and a thermal decomposition type foaming agent.
  • the cell nucleus adjusting agent include zinc compounds such as zinc oxide and zinc stearate, and organic compounds such as citric acid and urea. Among these, zinc oxide is more preferable.
  • the blending amount of the cell nucleus adjusting agent is preferably 0.4 to 8 parts by mass, more preferably 0.5 to 5 parts by mass, and further preferably 0.8 to 2.5 parts by mass with respect to 100 parts by mass of the resin. It is.
  • the foamable composition contains additives generally used for foams such as antioxidants, heat stabilizers, colorants, flame retardants, antistatic agents, fillers, etc. You may do it.
  • the method for producing the foamed sheet is not particularly limited.
  • the foamed sheet is produced by crosslinking a foamable composition containing a resin and a pyrolyzable foaming agent and heating the foamable composition to foam. More specifically, the manufacturing method includes the following steps (1) to (4).
  • Step (1) Mixing a resin and an additive containing a thermally decomposable foaming agent to form a sheet-like foamable composition (resin sheet)
  • Step (2) Converting the sheet-like foamable composition
  • Step (3) of irradiating ionizing radiation to crosslink the foamable composition Step (4) of heating the crosslinked foamable composition to foam the pyrolytic foaming agent to obtain a foamed sheet : A step of stretching the foam sheet in one or both of the MD direction and the TD direction
  • the method of forming the resin sheet is not particularly limited.
  • the resin and additives are supplied to an extruder and melt-kneaded, and the foamable composition is extruded into a sheet form from the extruder.
  • the resin sheet may be formed by
  • a method for crosslinking the foamable composition in the step (2) a method of irradiating the resin sheet with ionizing radiation such as electron beam, ⁇ ray, ⁇ ray, ⁇ ray and the like is used.
  • the irradiation amount of the ionizing radiation may be adjusted so that the degree of cross-linking of the foamed sheet to be obtained falls within the desired range described above, but is preferably 5 to 15 Mrad, and more preferably 6 to 13 Mrad.
  • the heating temperature when the foamable composition is heated to foam the pyrolyzable foaming agent may be not less than the foaming temperature of the pyrolyzable foaming agent, preferably 200 to 300 ° C.
  • the temperature is preferably 220 to 280 ° C.
  • the stretching of the foam sheet in the step (4) may be performed after foaming the resin sheet to obtain the foam sheet, or may be performed while foaming the resin sheet.
  • the foamed sheet when the foamed sheet is stretched after foaming the resin sheet, the foamed sheet may be stretched continuously while maintaining the molten state at the time of foaming without cooling the foamed sheet. After the foam sheet is cooled, the foam sheet may be stretched again by heating it to a molten or softened state. The foam sheet is easily thinned by stretching.
  • the draw ratio of the foamed sheet in one or both of the MD direction and the TD direction is preferably 1.1 to 5.0 times, more preferably 1.5 to 4.0 times.
  • the foamed sheet may be heated to, for example, 100 to 280 ° C., preferably 150 to 260 ° C. during stretching.
  • the foamed sheet obtained as described above may be cut into a desired shape by cutting by a known method such as punching.
  • a foamed sheet may be obtained by a method other than the above.
  • an organic peroxide may be blended in advance in the foamable composition, and crosslinking may be performed by a method in which the foamable composition is heated to decompose the organic peroxide. Good.
  • the step (4) that is, stretching of the foam sheet may be omitted.
  • a foam sheet is not specifically limited, For example, it is preferable to use it inside an electronic device. Since the foamed sheet of the present invention is thin and has high impact resistance and moderate flexibility even when the width is narrowed, it can be suitably used in various portable electronic devices in which the space for placing the foamed sheet is small. Examples of portable electronic devices include mobile phones, cameras, game machines, electronic notebooks, tablet terminals, and notebook personal computers.
  • the foam sheet can be used as an impact absorbing material and a sealing material inside the electronic device.
  • the pressure-sensitive adhesive tape includes, for example, a foam sheet and a pressure-sensitive adhesive layer provided on at least one surface of the foam sheet, but a double-sided pressure-sensitive adhesive tape provided with a pressure-sensitive adhesive layer on both sides is preferable.
  • the thickness of the pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive tape is preferably 5 to 200 ⁇ m.
  • the thickness of the pressure-sensitive adhesive layer is more preferably 7 to 150 ⁇ m, still more preferably 10 to 100 ⁇ m. When the thickness of the pressure-sensitive adhesive layer is in the range of 5 to 200 ⁇ m, the thickness of the structure fixed using the pressure-sensitive adhesive tape can be reduced.
  • an adhesive used for an adhesive layer For example, an acrylic adhesive, a urethane type adhesive, a rubber-type adhesive etc. can be used. Further, a release sheet such as a release paper may be further bonded on the pressure-sensitive adhesive layer.
  • the method for forming the pressure-sensitive adhesive layer on at least one surface of the foamed sheet is not particularly limited, but the following methods are exemplified.
  • a method of applying an adhesive on at least one surface of a foam sheet using a coater or the like a method of spraying and applying an adhesive using a spray on at least one surface of a resin foam sheet, on at least one surface of a foam sheet
  • a method of applying a pressure-sensitive adhesive using a brush a method of transferring a pressure-sensitive adhesive layer formed on a release sheet to at least one surface of a foamed sheet, and the like.
  • the measurement method and evaluation method of each physical property are as follows.
  • the degree of crosslinking (% by mass) was calculated by the following formula.
  • Crosslinking degree (% by mass) 100 ⁇ (B / A) ⁇ Closed cell ratio> It was measured according to the method described in the specification.
  • the 10% and 25% compressive strengths (C 20 ) are JIS except that a foam sheet is punched into 20 mm ⁇ 20 mm to obtain a sample, and the sample is used to obtain a thickness of one sheet. Measurement was performed according to K6767. 10% and 25% compressive strength (C 1 ) was obtained by punching a foam sheet into 1.0 mm ⁇ 20 mm to obtain samples, and placing the 20 samples on a measuring machine so that the sheets do not overlap each other. % And 25% compression strength (C 20 ) were measured in the same manner. In addition, the foam sheet of a present Example and the comparative example was sampled so that the longitudinal direction of a sample might correspond to MD direction.
  • the weight average molecular weight was measured by a GPC method using “2690 Separations Model” manufactured by Water Co. as a column, which was 600,000. 15 parts by mass of polymerized rosin ester having a softening point of 135 ° C., ethyl acetate (Fuji Kagaku) with respect to 100 parts by mass of the solid content of the acrylic copolymer (z) contained in the solution of the obtained acrylic copolymer (z) 125 parts by mass of Yakuhin Co., Ltd.
  • a pressure-sensitive adhesive (Z) The degree of crosslinking of the acrylic pressure-sensitive adhesive was 33% by mass.
  • a release paper having a thickness of 150 ⁇ m was prepared, an adhesive (Z) was applied to the release surface of the release paper, and dried at 100 ° C. for 5 minutes to form an acrylic adhesive layer having a thickness of 30 ⁇ m. .
  • This acrylic pressure-sensitive adhesive layer was bonded to the surface of a base material made of a foam sheet.
  • the same acrylic pressure-sensitive adhesive layer as above was bonded to the opposite surface of the substrate.
  • a double-sided pressure-sensitive adhesive tape whose both surfaces were covered with a release paper having a thickness of 150 ⁇ m was obtained.
  • FIG. 1 shows a schematic diagram of an impact resistance test apparatus.
  • the impact resistance test apparatus was produced by the following procedure. First, the double-sided adhesive tape obtained above was punched out so that the outer diameter was 15.0 mm in width, 15.0 mm in length, the inner diameter was 13.6 mm in width, and 13.6 mm in length. A test piece 1 having a square frame shape of 7 mm was prepared. Next, as shown in FIG. 1 (a), a polycarbonate or SUS-made adherence plate 3 having a square hole 2 provided in the center is prepared, and the test piece 1 from which the release paper has been peeled off is used as the adherence plate 3 Affixed over the entire outer periphery of the hole 2 on the upper surface.
  • a glass-made adherend plate 4 of a size covering the hole 2 was laminated and pasted on the test piece 1, and the hole 2 was covered to assemble an impact resistance test apparatus. Then, with the impact resistance test apparatus turned upside down and with the adherend plate 3 on the upper surface, a pressure of 5 kgf is applied for 5 seconds from the adherend plate 3 side, and the adherend plate 3 and the test piece positioned vertically. And were allowed to stand at room temperature for 36 hours. In the impact resistance test, the case where the adherend plate 3 was made of polycarbonate (PC) and SUS was evaluated.
  • PC polycarbonate
  • the produced impact resistance test apparatus is fixed to the support base 5, and an iron ball 6 weighing 50 g passing through the hole 2 formed in the adherend plate 3 is attached. , Dropped to pass through hole 2. Gradually increase the height at which the iron ball is dropped, and measure the height at which the iron ball was dropped when the test piece and the adherend peeled off due to the impact applied by dropping the iron ball to evaluate impact resistance did.
  • the adherend plate 3 was polycarbonate, it was 32 cm or more, and when it was SUS, it was evaluated as “A”.
  • the adherend plate 3 When the adherend plate 3 is made of polycarbonate, it is less than 32 cm, and when it is made of SUS, it is 38 cm or more, or when the adherend plate 3 is made of polycarbonate, it is more than 32 cm, and when made of SUS, it is less than 38 cm. This case was evaluated as “B”. The case where the adherend plate 3 was less than 32 cm when it was polycarbonate and less than 38 cm when it was made of SUS was evaluated as “C”.
  • Example 1 100 parts by mass of a linear low-density polyethylene resin (resin A) obtained by a polymerization catalyst of a metallocene compound, 3.4 parts by mass of azodicarbonamide having a particle size of 13 ⁇ m as a thermal decomposable foaming agent, and a cell nucleus regulator 1.0 part by mass of zinc oxide (trade name “OW-212F” manufactured by Sakai Chemical Industry Co., Ltd.) and 0.5 part by mass of an antioxidant were supplied to the extruder. Next, it was melt-kneaded at 130 ° C. and extruded into a long resin sheet having a thickness of 260 ⁇ m.
  • a linear low-density polyethylene resin (resin A) obtained by a polymerization catalyst of a metallocene compound 3.4 parts by mass of azodicarbonamide having a particle size of 13 ⁇ m as a thermal decomposable foaming agent, and a cell nucleus regulator 1.0 part by mass of zinc oxide (
  • the resin A As the resin A, a trade name “Affinity PL1850” (density 0.902 g / cm 3 ) manufactured by Dow Chemical Co., Ltd. was used. Next, 7 Mrad of an electron beam with an acceleration voltage of 500 kV was irradiated on both surfaces of the long resin sheet to crosslink the resin sheet. Thereafter, the cross-linked resin sheet was continuously fed into a foaming furnace maintained at 250 ° C. with hot air and an infrared heater and heated to be foamed to obtain a foamed sheet having a thickness of 300 ⁇ m. Subsequently, the obtained foam sheet was continuously sent out from the foaming furnace.
  • the foam sheet is stretched at a stretch ratio of 2.0 times in the TD direction while maintaining the temperature of the both surfaces at 200 to 250 ° C., and the foam sheet is supplied to the foam furnace.
  • the foamed sheet was stretched also in the MD direction by winding the foamed sheet at a winding speed higher than the feeding speed (supply speed) to obtain a foamed sheet.
  • the winding speed of the foam sheet was adjusted in consideration of the expansion in the MD direction due to foaming of the resin sheet itself.
  • the obtained foamed sheet was evaluated according to the above evaluation method, and the results are shown in Table 1.
  • Examples 2 to 7, Comparative Examples 1 to 3 The composition of the polyolefin resin composition was changed as shown in Tables 1 and 2, and the dose at the time of crosslinking was adjusted to be the degree of crosslinking in Tables 1 and 2, and the TD draw ratio was 2.0 times to It implemented similarly to Example 1 except the point adjusted to 3.5 time.
  • the polyolefin resin used in Example 6 is as follows.
  • Resin B Ethylene / vinyl acetate copolymer resin, manufactured by Mitsubishi Chemical Corporation, trade name “Novatec EVA”
  • Resin C Linear low density polyethylene, manufactured by Prime Polymer Co., Ltd., trade name “Evaflex 460-H”
  • the rate of decrease in compressive strength ((C 20 -C 1 ) / C 20 ) is 60% or less, and it does not become too flexible even when the sheet width is narrowed. And the impact resistance was sufficiently high.
  • the rate of decrease in compressive strength was higher than 60%. Therefore, when the sheet width was narrowed, the sheet became too flexible and the impact resistance could not be sufficiently increased.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
  • Adhesive Tapes (AREA)
PCT/JP2018/013834 2017-03-31 2018-03-30 架橋樹脂発泡シート、その製造方法、及び粘着テープ WO2018181982A1 (ja)

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CN201880018702.9A CN110446747B (zh) 2017-03-31 2018-03-30 交联树脂发泡片、其制造方法、以及胶带
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CN112778565A (zh) * 2020-12-30 2021-05-11 广德祥源新材科技有限公司 一种耐冲击的超薄型聚烯烃发泡片材及其制备方法和应用

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JPWO2018181982A1 (ja) 2019-08-08
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