Resin composition, laminate, and hollow molded body

Abstract

This resin composition contains 1 to 30 mass% of a modified homopolyolefin (A) modified with an unsaturated carboxylic acid or a derivative thereof, 1 to 40 mass% of an ethylene-α-olefin copolymer (B), and 50 to 98 mass% of a homopolypropylene (C) having a melting point of 155°C or more as measured by DSC, provided that the total of the modified homopolyolefin (A), the copolymer (B), and the homopolypropylene (C) is 100 mass%.

Description

Resin compositions, laminates, and hollow molded articles

[0001] The present invention relates to resin compositions, laminates, and hollow molded articles.

[0002] Polypropylene has long been widely used as a thermoplastic molding material with excellent rigidity, heat resistance, and transparency. However, because polypropylene is a non-polar material, it has poor adhesion to polar materials. To improve adhesion, a widely known technique involves modifying polypropylene with unsaturated carboxylic acids or their derivatives.

[0003] Furthermore, when materials containing modified polypropylene are used in hollow molded bodies such as tubes, heat-resistant adhesion is required during processes such as bending the tubes and corrugating (bellows) them.

[0004] For example, Patent Document 1 describes a composite material exhibiting excellent peel strength between a polypropylene adhesive resin layer and a metal layer. In applications where the composite material is exposed to high-temperature environments, further improvement in heat resistance may be required.

[0005] Japanese Patent Publication No. 2020-093428

[0006] Since flexibility is important for the development of adhesive properties, conventional polypropylene resin compositions described in Patent Document 1, etc., are compositions mainly composed of random polypropylene. On the other hand, for applications where heat resistance is required, there is a need to develop compositions mainly composed of homopolypropylene (i.e., containing 50% or more by mass of homopolypropylene in 100% by mass of the composition).

[0007] The present invention aims to provide a resin composition capable of forming a laminate with excellent heat resistance, as well as a laminate and a hollow molded article using the same.

[0008] In other words, the present invention and means for solving the above problems relate, for example, to the following [1] to [9]. [1] A resin composition comprising 1 to 30% by mass of a modified homopolyolefin (A) modified with an unsaturated carboxylic acid or a derivative thereof, 1 to 40% by mass of an ethylene-α-olefin copolymer (B), and 50 to 98% by mass of homopolypropylene (C) having a melting point of 155°C or higher as measured by DSC (provided that the total of the modified homopolyolefin (A), copolymer (B), and homopolypropylene (C) is 100% by mass).

[0009] [2] The resin composition according to [1], wherein the content of constituent units derived from an unsaturated carboxylic acid or its derivative, relative to the total mass of the resin composition, is 0.03 to 0.10% by mass. [3] The resin composition according to [1] or [2], wherein the intrinsic viscosity of the modified homopolyolefin (A), measured in decalin solvent at 135°C, is 0.40 to 1.20 dL / g.

[0010] [4] A laminate comprising an adhesive layer (I) made of the resin composition described in any of [1] to [3], and a resin layer (II) having polar groups provided on at least one side of the adhesive layer (I). [5] The laminate according to [4], wherein the resin layer (II) comprises at least one resin selected from the group consisting of polyamide resins and ethylene vinyl alcohol copolymers. [6] The laminate according to [4] or [5], further comprising a polyolefin resin layer (III) formed on the surface of the adhesive layer (I) that is not in contact with the resin layer (II).

[0011] [7] A hollow molded article comprising a laminate as described in any of [4] to [6]. [8] The hollow molded article described in [7], which is a tube for cooling piping. [9] The hollow molded article described in [7], which is a tube for fuel components.

[0012] According to the present invention, it is possible to provide a resin composition capable of forming a laminate with excellent heat resistance, as well as a laminate and a hollow molded article using the same.

[0013] The present invention will now be described in detail, specifically focusing on an example of a preferred embodiment. These descriptions and examples are illustrative and do not limit the scope of the embodiments. In this specification, numerical ranges indicated by "~" mean a range that includes the numbers before and after "~" as the lower and upper limits, respectively. In this specification, "%" indicating the amount of contained components is based on mass unless otherwise specified.

[0014] [Resin Composition] The resin composition of the present invention (hereinafter also referred to as "this composition") contains 1 to 30% by mass of a modified homopolyolefin (A) modified with an unsaturated carboxylic acid or its derivative, 1 to 40% by mass of an ethylene-α-olefin copolymer (B), and 50 to 98% by mass of homopolypropylene (C) having a melting point of 155°C or higher as measured by DSC (provided that the total of the modified homopolyolefin (A), copolymer (B), and homopolypropylene (C) is 100% by mass).

[0015] <Modified Homopolyolefin (A)> This composition contains modified homopolyolefin (A). Modified homopolyolefin (A) contributes to improving the peel strength of the adhesive layer (I) to the resin layer (II) having polar groups. Modified homopolyolefin (A) may be used alone or in combination of two or more types.

[0016] Modified homopolyolefin (A) is obtained by grafting an unmodified homopolyolefin with an unsaturated carboxylic acid or a derivative thereof.

[0017] Examples of olefins constituting the unmodified homopolyolefin include ethylene and propylene, with propylene being preferred.

[0018] Examples of unsaturated carboxylic acids include unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, and isocrotonic acid; and unsaturated dicarboxylic acids such as maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, and nadic acid (registered trademark) (endosis-bicyclo[2,2,1]hept-5-ene-2,3-dicarboxylic acid).

[0019] Examples of derivatives of unsaturated carboxylic acids include acid halide compounds, amide compounds, imide compounds, acid anhydrides, and ester compounds of the aforementioned unsaturated carboxylic acids. Specific examples of derivatives of unsaturated carboxylic acids include malenyl chloride, maleimide, maleic anhydride, citraconic anhydride, monomethyl maleate, dimethyl maleate, and glycidyl maleate.

[0020] Among these unsaturated carboxylic acids or their derivatives, unsaturated dicarboxylic acids or their acid anhydrides are preferred, maleic acid, nadic acid (registered trademark), or their acid anhydrides are more preferred, and maleic acid or maleic anhydride is even more preferred.

[0021] Graft modification of unmodified homopolyolefins can be carried out by various conventionally known methods, such as the following: (1) A method of graft modification (graft copolymerization) by melting unmodified homopolyolefins and adding unsaturated carboxylic acids, etc. (2) A method of graft modification (graft copolymerization) by dissolving unmodified homopolyolefins in a solvent and adding unsaturated carboxylic acids, etc.

[0022] In graft modification, one preferred embodiment is to perform graft modification (graft copolymerization) of unsaturated carboxylic acids, etc., in the presence of a radical polymerization initiator.

[0023] Examples of the radical polymerization initiators include benzoyl peroxide, dichlorobenzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(peroxidebenzoate)-3-hexine, 1,4-bis(tert-butylperoxyisopropyl)benzene, lauroyl peroxide, tert-butyl peracetate, and 2,5-dimethyl-2,5-di-(tert-butylperoxide)-3-hexine. Examples include organic peroxides such as 2,5-dimethyl-2,5-di(tert-butylperoxide)hexane, tert-butylperbenzoate, tert-butylperphenylacetate, tert-butylperisobutyrate, tert-butylper-sec-octoate, tert-butylperpivalate, cumylperpivalate, and tert-butylperdiethylacetate; and azo compounds such as azobisisobutyronitrile and dimethylazoisobutyrate.

[0024] The radical polymerization initiator is typically used in an amount of 0.001 to 1 part by mass, preferably 0.005 to 0.5 parts by mass, and more preferably 0.01 to 0.3 parts by mass, per 100 parts by mass of the homopolyolefin before modification.

[0025] The reaction temperature during graft modification is typically in the range of 60 to 350°C, preferably 150 to 300°C.

[0026] The intrinsic viscosity of the modified homopolyolefin (A), measured in decalin solvent at 135°C, is preferably 0.40 to 1.20 dL / g, more preferably 0.70 to 1.00 dL / g, and even more preferably 0.80 to 1.00 dL / g. When the intrinsic viscosity is within this range, the peel strength of the adhesive layer (I) to the resin layer (II) having polar groups is excellent. The intrinsic viscosity can be measured by the method described in the examples below.

[0027] The melt flow rate (MFR) of the modified homopolyolefin (A) is preferably 50 to 1,500 g / 10 min, more preferably 80 to 1,300 g / 10 min, and even more preferably 100 to 1,000 g / 10 min. The MFR is measured according to ASTM D1238 under conditions of a temperature of 180°C and a load of 2.16 kg.

[0028] <Ethylene-α-olefin copolymer (B)> This composition contains ethylene-α-olefin copolymer (B) (hereinafter also referred to as "polymer (B)"). One type of copolymer (B) may be used, or two or more types may be used.

[0029] Examples of α-olefins in copolymer (B) include α-olefins having 3 to 20 carbon atoms, specifically linear α-olefins having 3 to 20 carbon atoms, preferably 3 to 10 carbon atoms, such as propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene; and branched α-olefins having 5 to 20 carbon atoms, preferably 5 to 10 carbon atoms, such as 3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4-ethyl-1-hexene, and 3-ethyl-1-hexene. Among these, α-olefins having 3 to 10 carbon atoms are preferred, and α-olefins having 3 to 8 carbon atoms are more preferred. From the viewpoint of having particularly excellent adhesive strength, propylene is the most preferred α-olefin. One type of α-olefin may be used, or two or more types of α-olefins may be used.

[0030] The content of ethylene-derived constituent units in copolymer (B) (hereinafter also referred to as "ethylene content") is preferably 50 to 99 mol%, more preferably 60 to 95 mol%, and even more preferably 70 to 90 mol%. When the ethylene content is within the above range, it is preferable in that the adhesive layer (I) exhibits excellent adhesion to the resin layer (II) having polar groups while maintaining the rigidity of the adhesive layer (I).

[0031] In the copolymer (B), the content ratio of α-olefin-derived structural units (hereinafter also referred to as "α-olefin content") is preferably 1 to 50 mol%, more preferably 5 to 40 mol%, still more preferably 10 to 30 mol%.

[0032] Here, when the total amount of structural units derived from all monomers constituting the copolymer (B) is 100 mol%, the content ratio of each structural unit is 13 can be measured by 13C-NMR.

[0033] The melt flow rate (MFR) of the copolymer (B) is preferably 0.1 to 50 g / 10 min, more preferably 0.3 to 40 g / 10 min, still more preferably 0.5 to 20 g / 10 min. The MFR is measured in accordance with ASTM D1238 under conditions of a temperature of 190°C and a load of 2.16 kg.

[0034] The density of the copolymer (B) is preferably 0.80 to 0.91 g / cm 3 , more preferably 0.85 to 0.90 g / cm 3 , still more preferably 0.87 to 0.90 g / cm 3 , most preferably 0.865 to 0.90 g / cm 3 . The density is measured in accordance with JIS K 7112-2:2023 (density gradient tube method).

[0035] The copolymer (B) may be a random copolymer or a block copolymer, and is preferably a random copolymer.

[0036] The method for producing the copolymer (B) is not particularly limited. The copolymer (B) can be produced, for example, according to a conventionally known method using a well-known catalyst such as a Ziegler-Natta catalyst or a metallocene catalyst.

[0037] <Homopolypropylene (C)> The present composition contains homopolypropylene (C). One type of homopolypropylene (C) may be used, or two or more types thereof may be used.

[0038] The melting point of homopolypropylene (C), as measured by differential scanning calorimetry (DSC), is 155°C or higher, preferably 160°C or higher. A melting point within the aforementioned range is preferable because it allows bending processing and corrugating processing to be performed at higher temperatures.

[0039] The melt flow rate (MFR) of homopolypropylene (C) is preferably 0.1 to 30 g / 10 min, more preferably 0.3 to 20 g / 10 min, and still more preferably 0.5 to 10 g / 10 min. The MFR is measured in accordance with ASTM D1238 under conditions of a temperature of 230°C and a load of 2.16 kg.

[0040] The density of homopolypropylene (C) is preferably 0.88 to 0.92 g / cm 3 , more preferably 0.89 to 0.91 g / cm 3 . The density is measured in accordance with JIS K 7112-2:2023 (density gradient tube method).

[0041] <Other Components> The present composition may contain other components in addition to the modified homopolyolefin (A), copolymer (B), and homopolypropylene (C) described above. Examples of such other components include pigments, dyes, fillers, lubricants, plasticizers, antioxidants, flame retardants, ultraviolet absorbers, antibacterial agents, surfactants, antistatic agents, weathering stabilizers, heat resistance stabilizers, anti-slip agents, anti-blocking agents, crystallization aids, anti-fogging agents, anti-aging agents, impact modifiers, crosslinking agents, co-crosslinking agents, crosslinking aids, adhesives, softeners, and processing aids. One of these other components may be used alone, or two or more thereof may be used in combination.

[0042] <Composition Ratio of the Present Composition> The present composition contains 1 to 30% by mass of modified homopolyolefin (A), 1 to 40% by mass of copolymer (B), and 50 to 98% by mass of homopolypropylene (C), provided that the total of the modified homopolyolefin (A), copolymer (B), and homopolypropylene (C) is 100% by mass. When the composition ratio of the present composition is in this embodiment, it is easy to form a laminate excellent in adhesion to resins having a polar group and in heat resistance.

[0043] When the total of the modified homopolyolefin (A), copolymer (B), and homopolypropylene (C) is 100% by mass, the content of the modified homopolyolefin (A) is preferably 1 to 15% by mass, more preferably 2 to 10% by mass.

[0044] When the total of the modified homopolyolefin (A), copolymer (B), and homopolypropylene (C) is 100% by mass, the content of copolymer (B) is preferably 5 to 40% by mass, more preferably 10 to 40% by mass.

[0045] When the total of the modified homopolyolefin (A), copolymer (B), and homopolypropylene (C) is taken as 100% by mass, the content of homopolypropylene (C) is preferably 60 to 95% by mass, more preferably 65 to 90% by mass.

[0046] <Physical Properties of the Composition> The content of constituent units derived from unsaturated carboxylic acids or their derivatives relative to the total mass of the composition (hereinafter referred to as "graft modification amount of the composition") is preferably 0.03 to 0.10% by mass, more preferably 0.03 to 0.07% by mass. When the graft modification amount of the composition is within the above range, the peel strength of the adhesive layer (I) to the resin layer (II) having polar groups is excellent. If the graft modification amount of the composition is lower than the lower limit, there tends to be a shortage of reaction sites with the resin having polar groups. Also, if the graft modification amount of the composition is higher than the upper limit, there tends to be a decrease in thermal stability due to an increase in low-melting-point components in the composition. The graft modification amount of the composition can be measured by the method described in the examples below.

[0047] Despite the low graft modification level and limited reaction sites with polar groups, which would normally be unfavorable for adhesion to polar groups, this composition exhibits high adhesion. The reason for this is unclear, but it is presumed to be as follows: The intrinsic viscosity of the modified homopolyolefin (A) is within a moderate range, as described above, resulting in sufficiently long polymer chains and enhanced intermolecular entanglement. Due to the length of the polymer chains, not only the chemical reaction with the polar groups but also the physical entanglement of molecules contributes to adhesion. As a result, it is thought that high adhesive strength was achieved even with a small number of reaction sites (modification level).

[0048] The melt flow rate (MFR) of this composition is preferably 0.1 to 50 g / 10 min, more preferably 0.5 to 30 g / 10 min, and even more preferably 1.0 to 10 g / 10 min, from the viewpoint of moldability. The MFR is measured according to ASTM D1238 under conditions of a temperature of 230°C and a load of 2.16 kg.

[0049] <Method for preparing the composition> A known method can be used to prepare the composition. For example, a method can be used in which a modified homopolyolefin (A), copolymer (B), homopolypropylene (C), and other components that may be added as needed are melt-kneaded together or sequentially. As a method of melt-kneading, for example, each component to be added to the composition may be dry-blended as needed, and then melt-kneaded using a single-screw or twin-screw extruder, Banbury mixer, roll, various kneaders, etc., and industrially, a single-screw or twin-screw extruder is preferably used. The temperature during melt-kneading is not particularly limited as long as each component to be added to the composition is melted, but it is usually 160 to 300°C, preferably 180 to 250°C.

[0050] [Laminate] The laminate according to the present invention comprises an adhesive layer (I) made of the composition, and a resin layer (II) having polar groups provided on at least one side of the adhesive layer (I).

[0051] <Adhesive layer (I)> The adhesive layer (I) is formed from this composition. The adhesive layer (I) has excellent peel strength against the resin layer (II) having polar groups.

[0052] The lower limit of the thickness range of the adhesive layer (I) is preferably 50 μm or more, more preferably 100 μm or more, and the upper limit of the thickness range is not particularly limited, but for example, it is 700 μm.

[0053] <Resin layer (II) containing polar groups> The resin layer (II) containing polar groups (hereinafter also referred to as "polar resin layer (II)") contains a resin containing polar groups. A resin containing polar groups is a resin that has monovalent or divalent polar groups in its molecule. Examples of monovalent or divalent polar groups include monovalent functional groups such as hydroxyl groups, carboxyl groups, amino groups, alkyl ester groups, isocyanate groups, and glycidyl groups, and divalent functional groups that form ester bonds, amide bonds, urethane bonds, urea bonds, ether bonds, carbonyl bonds, etc.

[0054] Suitable resins having such polar groups include, for example, olefin polymers, polyamide resins, and ethylene-vinyl alcohol copolymers having polar groups. In one more preferred embodiment, the polar resin layer (II) contains at least one resin selected from the group consisting of polyamide resins and ethylene-vinyl alcohol copolymers, and in another even more preferred embodiment, it contains a polyamide resin.

[0055] Examples of polyamide resins include nylon 6, nylon 66, nylon 610, nylon 9, nylon 11, nylon 12, nylon 6 / 66, nylon 66 / 610, nylon 6 / 11, MXD nylon, amorphous nylon, and terephthalic acid / adipic acid / hexamethylenediamine copolymer. Among these, nylon 6, nylon 11, and nylon 12 are preferred because their melting points are close to those of homopolypropylene (C).

[0056] Preferably, the ethylene-vinyl alcohol copolymer has an ethylene-derived constituent unit content (ethylene content) of 15 to 65 mol%, more preferably 25 to 48 mol%. Such an ethylene-vinyl alcohol copolymer can be produced by saponifying a copolymer of ethylene and vinyl acetate, and the copolymer used is saponified to a degree of saponification of preferably 50% or more, more preferably 90% or more. The upper limit of the degree of saponification is 100%. Generally, if the ethylene content of the ethylene-vinyl alcohol copolymer is too low, it is prone to thermal decomposition, making melt molding difficult, and it also has poor stretchability and tends to absorb water and swell easily, resulting in reduced water resistance. On the other hand, if the ethylene content of the ethylene-vinyl alcohol copolymer is too high, it tends to have reduced gas permeability. Also, if the degree of saponification is too low, it tends to have reduced gas permeability.

[0057] The lower limit of the thickness range of the polar resin layer (II) is preferably 300 μm or more, more preferably 400 μm or more, and the upper limit of the thickness range is not particularly limited, but for example it is 800 μm.

[0058] <Polyolefin resin layer (III)> The laminate may further include a polyolefin resin layer (III). The polyolefin resin layer (III) is formed, for example, on a surface of the adhesive layer (I) that is not in contact with the polar resin layer (II). That is, the laminate may have a configuration of polar resin layer (II) / adhesive layer (I) / polyolefin resin layer (III).

[0059] Examples of polyolefin resins used in the polyolefin resin layer (III) include thermoplastic polyolefin resins such as polyethylene and polypropylene. One type may be used, or two or more types may be used. Using polypropylene resin is preferable from the viewpoint of heat resistance. The polyolefin resin may be crosslinked.

[0060] The lower limit of the thickness range of the polyolefin resin layer (III) is preferably 300 μm or more, more preferably 400 μm or more, and the upper limit of the thickness range is not particularly limited, but for example it is 800 μm.

[0061] <Other layer (IV)> The laminate may further include another layer (IV). The other layer (IV) is formed, for example, on the surface of the polyolefin resin layer (III) that is further away from the polar resin layer (II). That is, the laminate may have the configuration of polar resin layer (II) / adhesive layer (I) / polyolefin resin layer (III) / other layer (IV).

[0062] In one embodiment, the other layer (IV) is a layer formed from the composition described above. Here, the composition forming the other layer (IV) may be the same as or different from the composition forming the adhesive layer (I), as long as it is a composition included in the composition described above.

[0063] Furthermore, in another embodiment, the other layer (IV) includes, for example, at least one resin selected from known acid-modified polyolefin resins and their crosslinked forms. Examples of acid-modified polyolefin resins include acid-modified thermoplastic polyolefin resins such as acid-modified polyethylene and acid-modified polypropylene. One of these may be used, or two or more may be used. Using acid-modified polypropylene is preferable from the viewpoint of heat resistance.

[0064] <Structure of the Laminate> Examples of the structure of the laminate according to the present invention include: polar resin layer (II) / adhesive layer (I), polar resin layer (II) / adhesive layer (I) / polyolefin resin layer (III), polar resin layer (II) / adhesive layer (I) / polyolefin resin layer (III) / other layer (IV), polar resin layer (II) / adhesive layer (I) / polar resin layer (II), polyolefin resin layer (III) / adhesive layer (I) / polar resin layer (II) / adhesive layer (I) / polyolefin resin layer (III), other layer (IV) / polyolefin resin layer (III) / adhesive layer (I) / polar resin layer (II) / adhesive layer (I) / polyolefin resin layer (III) / other layer (IV).

[0065] The lower limit of the total thickness range of the laminate is preferably 650 μm or more, more preferably 900 μm or more, and the upper limit of the total thickness range is not particularly limited, but for example, 2300 μm.

[0066] <Method for Manufacturing Laminates> As a method for manufacturing laminates according to the present invention, conventionally known methods can be employed. For example, co-extrusion is a method in which individual molten resins melted in an extruder are supplied to a multilayer die to form an inflation film, T-die film, sheet, pipe, etc., which are laminated in the die, and co-injection molding is a method in which molten individual resins are injected into the same mold with a time lag, but the invention is not limited to these. It is also possible to obtain a laminate by applying heat to the resin films that make up each layer and laminating them together.

[0067] When a polyolefin resin layer (III) and other layers (IV) are provided as needed, films corresponding to the adhesive layer (I), the polyolefin resin layer (III), and other layers (IV) as needed are pre-formed and a laminated film is produced by heat bonding or the like. Alternatively, the laminated film may be produced by forming the adhesive layer (I), the polyolefin resin layer (III), and other layers (IV) as needed using a known multilayer molding method. Examples of known multilayer molding methods include co-extrusion molding and extrusion lamination.

[0068] <Shape of the Laminate> The shape of the laminate is arbitrary and may be sheet-like or hollow (tubular, bottle-like, etc., with a hollow interior). A tubular shape is preferred for the hollow form. The laminate may also have corrugated regions. A corrugated region is a region formed in a corrugated shape, bellows shape, accordion shape, or corrugated shape, etc. The corrugated region may not only be present along the entire length of the laminate, but may also be present in appropriate regions along the way.

[0069] [Molded Article] The laminate according to the present invention can be used in the manufacture of a molded article. That is, the molded article includes the laminate. Specific examples of molded articles include injection molded articles, foamed molded articles, injection foamed molded articles, extruded articles, hollow molded articles, vacuum / pressure molded articles, calendered articles, stretched films, and inflation films, with hollow molded articles being particularly preferred.

[0070] Hollow molded bodies are suitable for use in multilayer tubes, multilayer hoses, and the like because they have excellent adhesion to resins containing polar groups and excellent heat resistance. Examples of multilayer tubes or hoses include refrigerant hoses such as cooling pipe tubes and air conditioner refrigerant hoses; fuel component tubes such as return hoses, fuel filler hoses, oil hoses, diesel gasoline hoses, and alcohol-containing gasoline hoses. In addition, examples of liquid and gas transport hoses include fuel-related feed hoses, evaporator hoses, ORVR hoses, reserve hoses, and vent hoses; and brake hoses and window hoses for vehicles and equipment. オ Examples include hoses for windshield coolant. Furthermore, hoses used for cooling and heating include engine coolant (LLC) hoses, reservoir tank hoses, heater hoses, heating hoses, and floor heating hoses. In addition, examples include hoses for transporting urea solution used in urea SCR systems; hoses for industrial applications such as oil drilling and paint spraying; hoses for infrastructure supply and gas; hoses for fire extinguishers and fire extinguishing equipment; and hoses for special-purpose medical cooling equipment. Among these, the hollow molded body is preferably used as a tube for cooling piping and a tube for fuel components.

[0071] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples. The materials, amounts used, proportions, and processing procedures shown in the following examples can be modified as appropriate without departing from the spirit of the present invention.

[0072] <Physical Property Measurement> <Melt Flow Rate (MFR)> The MFR of homopolypropylene (C) and the composition was measured according to ASTM D1238 at a temperature of 230°C and a load of 2.16 kg. The MFR of modified homopolypropylene (A) was measured according to ASTM D1238 at a temperature of 180°C and a load of 2.16 kg. The MFR of ethylene-α-olefin copolymer (B) was measured according to ASTM D1238 at a temperature of 190°C and a load of 2.16 kg.

[0073] <Graft Amount (M Value)> In the modified homopolypropylene (A), the amount of structural units derived from an unsaturated carboxylic acid and / or a derivative thereof (graft amount (M value)) is measured by an infrared absorption spectrometer at 1790 cm derived from said structural units -1 The peak intensity was measured and quantified using a pre-prepared calibration curve.

[0074] <<Density>> Density was measured in accordance with JIS K 7112-2:2023 (density gradient tube method).

[0075] <<Content Ratio of Structural Units>> Quantification of the content ratio of structural units derived from α-olefins such as propylene and butene, and structural units derived from ethylene in the copolymer is carried out by 13 C-NMR using the following apparatus and conditions.

[0076] A JECX400P nuclear magnetic resonance apparatus manufactured by JEOL Ltd. was used, a mixed solvent of deuterated ortho-dichlorobenzene / deuterated benzene (80 / 20% by volume) was used as the solvent, the sample concentration was 60 mg / 0.6 mL, the measurement temperature was 120°C, and the observed nucleus was 13 13C (100 MHz), the sequence was single pulse proton decoupling, the pulse width was 4.62 µsec (45° pulse), the repetition time was 5.5 seconds, the number of scans was 8000 times, and 29.73 ppm was adopted as the reference value for chemical shift.

[0077] <<Melting Point>> Melting point was measured as follows using a differential scanning calorimeter (DSC). About 5 mg of a sample was sealed in an aluminum pan, heated from room temperature to 230°C at a rate of 10°C / min, and the sample was held at 230°C for 10 minutes to completely melt it. Then, the sample was cooled to -20°C at 10°C / min, held at -20°C for 10 minutes, and then heated again to 230°C at 10°C / min. The peak temperature in this second heating test was adopted as the melting point (Tm).

[0078] <<Graft Modification Amount>> The content of structural units derived from an unsaturated carboxylic acid or a derivative thereof relative to the total mass of the composition (graft modification amount) was measured by an infrared absorption spectrometer at 1790 cm derived from said structural units -1 The peak intensity was measured and quantified using a pre-prepared calibration curve.

[0079] 《Intrinsic Viscosity [η]》 The sample was dissolved in decalin solvent, and the flow time of the solution was measured using a viscometer at 135°C. The intrinsic viscosity [η] was determined from the ratio of the flow time of the solution to that of a blank (pure solvent) measured in the same manner.

[0080] <Raw Materials> The polyolefins used in the examples and comparative examples are listed below. All of these polyolefins were polymerized according to conventional methods and optionally graft-modified with maleic anhydride.

[0081] Modified homopolypropylene (A1): Intrinsic viscosity [η] = 0.43 dL / g, MFR = 1,050 g / 10 min, M value = 3.0% Modified homopolypropylene (A2): Intrinsic viscosity [η] = 0.80 dL / g, MFR = 120 g / 10 min, M value = 1.0% Modified random polypropylene (a1): Intrinsic viscosity [η] = 0.90 dL / g, MFR = 110 g / 10 min Ethylene-α-olefin copolymer (B1): Ethylene-propylene copolymer (ethylene content 80 mol%, propylene content 20 mol%, MFR = 0.6 g / 10 min, density = 0.87 g / cm³) 3 ) Ethylene-α-olefin copolymer (B2): Ethylene-butene copolymer (ethylene content 89 mol%, butene content 11 mol%, MFR = 3.6 g / 10 min, density = 0.89 g / cm³) 3 Homopolypropylene (C): MFR = 2.0 g / 10 min, density = 0.90 g / cm³ 3 Melting point = 160°C

[0082] [Example 1] <Preparation of Composition 1> Composition 1 was obtained by melt-kneading 74% by mass of homopolypropylene (C), 20% by mass of ethylene-α-olefin copolymer (B1), and 6% by mass of modified homopolypropylene (A2) at 230°C using a single-screw extruder.

[0083] <Manufacturing of Laminate> PP (199X111239 Black) manufactured by RTP was melted at 250°C, composition 1 at 240°C, and PA12 (Vestamid® LX9008 Black) manufactured by Polypla Evonik at 280°C. Each resin was extruded from a multilayer molding machine to form a tube with an outer diameter of 8 mm and an inner diameter of 6 mm, which was then taken up while cooling. The thicknesses of the outer layer (PA12), intermediate layer (adhesive layer made of composition 1), and inner layer (PP) of the resulting laminate were 450 / 100 / 450 μm (total thickness 1000 μm).

[0084] <Aging treatment of the laminated material (150°C)> The obtained laminated tubes were left to stand in a 150°C oven for 15 minutes, and immediately after removal, they were rapidly cooled in ice water.

[0085] <Aging treatment of laminated structures (Immersion in LLC)> The obtained laminated tubes were immersed in LLC (ethylene glycol:distilled water = 1:1 solvent) and left standing at 90°C for 500 hours.

[0086] <Measurement of Adhesion Strength> <Adhesion strength after heat treatment and after immersion in LLC> Samples were cut to a width of 5 mm from laminated tubes that had been aged at 150°C and laminated tubes that had been aged by immersion in LLC, and these samples were used for measurement. For the measurement samples, the adhesion strength (unit: N / 5 mm) between the outer layer (PA12) and the intermediate layer (adhesive layer consisting of composition 1) was measured using a tensile testing machine with the T-peel method at room temperature of 23°C. The measured values ​​were converted to a unit of N / 15 mm. The crosshead speed was set to 50 mm / min. Scores were assigned to the adhesion strength after heat treatment and the adhesion strength after immersion in LLC, and these are listed in Table 1. The evaluation criteria are as follows.

[0087] (Adhesive strength after heat treatment) ×: Less than 10 N / 15 mm △: 10 N / 15 mm or more and less than 30 N / 15 mm ○: 30 N / 15 mm or more

[0088] (Adhesive strength after LLC immersion) ×: Less than 15N / 15mm △: 15N / 15mm or more and less than 30N / 15mm ○: 30N / 15mm or more

[0089] [Examples 2-7 and Comparative Example 1] Compositions were prepared in the same manner as in Example 1, except that the compositions were prepared according to the formulations shown in Table 1. Laminates were then manufactured and evaluated using the obtained compositions. The results are shown in Table 1.

[0090]

Claims

1. A resin composition comprising 1 to 30% by mass of a modified homopolyolefin (A) modified with an unsaturated carboxylic acid or its derivative, 1 to 40% by mass of an ethylene-α-olefin copolymer (B), and 50 to 98% by mass of homopolypropylene (C) having a melting point of 155°C or higher as measured by DSC (provided that the total of the modified homopolyolefin (A), copolymer (B), and homopolypropylene (C) is 100% by mass).

2. The resin composition according to claim 1, wherein the content of constituent units derived from an unsaturated carboxylic acid or its derivative is 0.03 to 0.10% by mass of the total mass of the resin composition.

3. The resin composition according to claim 1, wherein the intrinsic viscosity of the modified homopolyolefin (A), measured in decalin solvent at 135°C, is 0.40 to 1.20 dL / g.

4. A laminate comprising an adhesive layer (I) made of the resin composition described in claim 1, and a resin layer (II) having polar groups provided on at least one side of the adhesive layer (I).

5. The laminate according to claim 4, wherein the resin layer (II) comprises at least one resin selected from the group consisting of polyamide resins and ethylene vinyl alcohol copolymers.

6. The laminate according to claim 4, further comprising a polyolefin resin layer (III) formed on the surface of the adhesive layer (I) that is not in contact with the resin layer (II).

7. A hollow molded article comprising the laminate according to any one of claims 4 to 6.

8. The hollow molded body according to claim 7, which is a tube for cooling piping.

9. The hollow molded body according to claim 7, which is a tube for fuel components.

Images