3,4,5,6-tetrahydrophthalic acid metal salt, crystal nucleating agent for polyolefin-based resin, polyolefin-based resin composition, and polyolefin-based resin molded body

Abstract

The present invention provides a crystal nucleating agent for a polyolefin-based resin, the crystal nucleating agent being capable of improving the crystallization temperature of a polyolefin-based resin molded body. Moreover, the present invention provides: a 3,4,5,6-tetrahydrophthalic acid metal salt that can be used as said crystal nucleating agent for a polyolefin-based resin; a polyolefin-based resin composition using said crystal nucleating agent for a polyolefin-based resin; and a polyolefin-based resin molded body. 3,4,5,6-Tetrahydrophthalic acid metal salt.

Description

3,4,5,6-tetrahydrophthalic acid metal salt, crystal nucleating agent for polyolefin resin, polyolefin resin composition, and polyolefin resin molded product

[0001] The present invention relates to a metal salt of 3,4,5,6-tetrahydrophthalic acid, a crystal nucleating agent for polyolefin resins, a polyolefin resin composition, and a polyolefin resin molded article.

[0002] Polypropylene-based resins are known to have multiple crystalline polymorphs, such as α-crystals and β-crystals. Polypropylene-based resins are known to form α-crystals and β-crystals, which have different properties such as melting point and density, and are therefore attracting industrial attention.

[0003] Methods of controlling the crystal polymorphism of polypropylene resins by adding a crystal nucleating agent have been investigated. For example, Patent Document 1 discloses a technique in which polypropylene is melted and cooled together with a dicarboxylate of a metal of main group II of the periodic table as a β-nucleating agent or other common additives. Specifically, the technique describes a method for increasing the proportion of β crystals in polypropylene and the inclusion of a dicarboxylate of a metal of main group II of the periodic table as a β-nucleating agent.

[0004] Japanese Patent Application Publication No. 08-48828

[0005] The crystal nucleating agent described in Patent Document 1 has the ability to form β-crystals in polypropylene-based resins, but the crystallization-promoting effect is insufficient (the crystallization temperature is low), and there is room for further improvement.

[0006] Therefore, an object of the present invention is to provide a crystal nucleating agent for polyolefin resins that can improve the crystallization temperature of polyolefin resin molded articles. The present invention also provides a metal salt of 3,4,5,6-tetrahydrophthalic acid that can be used as the polyolefin resin crystal nucleating agent, a polyolefin resin composition using the polyolefin resin crystal nucleating agent, and a polyolefin resin molded article.

[0007] As a result of extensive investigations, the present inventors came up with the idea that the crystallization temperature of a polyolefin resin molded article can be improved by using a crystal nucleating agent containing a metal salt of 3,4,5,6-tetrahydrophthalic acid, and completed the present invention.

[0008] That is, the present invention relates to a metal salt of 3,4,5,6-tetrahydrophthalic acid.

[0009] In the metal 3,4,5,6-tetrahydrophthalic acid salt of the present invention, the metal salt is preferably a monovalent or divalent metal salt, and more preferably a zinc salt.

[0010] The present invention also relates to a crystal nucleating agent for polyolefin resins containing a metal salt of 3,4,5,6-tetrahydrophthalic acid. Furthermore, in the crystal nucleating agent for polyolefin resins of the present invention, the metal salt is preferably a monovalent or divalent metal salt. Furthermore, the metal salt is preferably a zinc salt. The present invention also relates to a polyolefin resin composition containing the crystal nucleating agent for polyolefin resins and a polyolefin resin. Furthermore, in the polyolefin resin composition of the present invention, the content of the metal salt of 3,4,5,6-tetrahydrophthalic acid in the polyolefin resin composition is preferably 100 ppm or more. Furthermore, the polyolefin resin is preferably a polypropylene resin. The present invention also relates to a polyolefin resin molded article made from the polyolefin resin composition and having a β-crystal content of 30% or more.

[0011] In the polyolefin resin crystal nucleating agent of the present invention, the metal salt is preferably a sodium salt or a calcium salt. The present invention also relates to a polyolefin resin composition containing the polyolefin resin crystal nucleating agent and a polyolefin resin. In the polyolefin resin composition of the present invention, the content of the 3,4,5,6-tetrahydrophthalic acid metal salt in the polyolefin resin composition is preferably 100 ppm or more. The polyolefin resin is preferably a polypropylene resin.

[0012] The present invention also relates to a polyolefin resin molded article made from the above polyolefin resin composition, which has a crystallization temperature of 126° C. or higher.

[0013] The present invention provides a crystal nucleating agent for polyolefin resins that can improve the crystallization temperature of polyolefin resin molded articles. The present invention also provides a metal salt of 3,4,5,6-tetrahydrophthalic acid that can be used as the polyolefin resin crystal nucleating agent, a polyolefin resin composition using the polyolefin resin crystal nucleating agent, and a polyolefin resin molded article.

[0014] <Metal 3,4,5,6-tetrahydrophthalic acid> The present invention is a metal 3,4,5,6-tetrahydrophthalic acid.

[0015] In the metal 3,4,5,6-tetrahydrophthalic acid salt of the present invention, the metal salt is preferably a monovalent or divalent metal salt, more preferably a sodium salt, a calcium salt, or a zinc salt from the viewpoint of obtaining a polyolefin-based crystal nucleating agent that can suitably increase the crystallization temperature of a polyolefin-based resin molded article, and even more preferably a zinc salt from the viewpoint of obtaining a polyolefin-based crystal nucleating agent that is excellent in β-crystal formation ability.

[0016] Metal 3,4,5,6-tetrahydrophthalic acid can be produced, for example, by ring-opening and neutralizing 3,4,5,6-tetrahydrophthalic anhydride with an aqueous sodium hydroxide solution to prepare disodium 3,4,5,6-tetrahydrophthalate, which can then be reacted with an aqueous solution of the metal salt. Alternatively, metal 3,4,5,6-tetrahydrophthalic anhydride can be directly reacted with an aqueous solution of the metal hydroxide salt.

[0017] <Crystal Nucleating Agent for Polyolefin Resin> The crystal nucleating agent for polyolefin resin of the present invention contains a metal salt of 3,4,5,6-tetrahydrophthalic acid. The crystal nucleating agent containing a metal salt of 3,4,5,6-tetrahydrophthalic acid can increase the crystallization temperature of a polyolefin resin molded article.

[0018] The metal salt is preferably a monovalent or divalent metal salt, more preferably a sodium salt, a calcium salt, or a zinc salt from the viewpoint of suitably increasing the crystallization temperature of the polyolefin resin molded article, and even more preferably a zinc salt from the viewpoint of excellent β-crystal forming ability.

[0019] The content of the metal salt of 3,4,5,6-tetrahydrophthalic acid is preferably 50% by mass or more and 100% by mass or less, and more preferably 70% by mass or more and 100% by mass or less, based on the total mass of the crystal nucleating agent for polyolefin resins.

[0020] The crystal nucleating agent for polyolefin resins of the present invention may contain additives.

[0021] Examples of the additives include various additives listed in the "Positive List Additives Handbook" (September 2004) compiled by the Hygienic Association of Polyolefins and Styrene Styrene Styrene etc. Specific examples include fluorescent whitening agents (2,5-thiophenediyl (5-t-butyl-1,3-benzoxazole), 4,4'-bis (benzoxazol-2-yl) stilbene, etc.), antioxidants, stabilizers (metal compounds, epoxy compounds, nitrogen compounds, phosphorus compounds, sulfur compounds, etc.), ultraviolet absorbers (benzophenone compounds, benzotriazole compounds, etc.), surfactants, lubricants (aliphatic hydrocarbons such as paraffin and wax, higher fatty acids having 8 to 22 carbon atoms, higher fatty acid metal salts (Al, Ca, etc.) having 8 to 22 carbon atoms, higher aliphatic alcohols having 8 to 22 carbon atoms, polyglycols, higher fatty acids having 4 to 22 carbon atoms and metal salts (Al, Ca, etc.) of higher fatty acids having 4 ... esters of C18 aliphatic monohydric alcohols, higher fatty acid amides having 8 to 22 carbon atoms, silicone oil, rosin derivatives, etc.), fillers (talc, hydrotalcite, mica, zeolite, perlite, diatomaceous earth, calcium carbonate, glass fiber, etc.), foaming agents, foaming aids, polymer additives, plasticizers (dialkyl phthalate, dialkyl hexahydrophthalate, etc.), crosslinking agents, crosslinking accelerators, antistatic agents, flame retardants, dispersants, organic and inorganic pigments (indigo compounds, phthalocyanine compounds, anthraquinone compounds, ultramarine compounds, cobalt aluminate compounds, etc.), processing aids, neutralizing agents, other nucleating agents, etc.

[0022] The content of the additive may be determined appropriately depending on the type of the additive, but is preferably, for example, 0.0001 to 100 parts by mass per 100 parts by mass of the metal salt of 3,4,5,6-tetrahydrophthalic acid.

[0023] <Polyolefin Resin Composition> The polyolefin resin composition of the present invention contains the above-described crystal nucleating agent for polyolefin resins and a polyolefin resin.

[0024] (Crystal nucleating agent for polyolefin-based resin) As the crystal nucleating agent for polyolefin-based resin, the above-mentioned crystal nucleating agent for polyolefin-based resin of the present invention may be used.

[0025] From the viewpoint of suitably imparting β-crystal formability, the content of the metal salt of 3,4,5,6-tetrahydrophthalic acid in the polyolefin resin composition of the present invention is preferably 100 ppm or more, more preferably 200 ppm or more, even more preferably 300 ppm or more, particularly preferably 400 ppm or more, and most preferably 500 ppm or more. The content of the metal salt of 3,4,5,6-tetrahydrophthalic acid in the polyolefin resin composition of the present invention is preferably 10,000 ppm or less, more preferably 5,000 ppm or less, even more preferably 3,000 ppm or less, particularly preferably 2,000 ppm or less, and most preferably 1,000 ppm or less.

[0026] (Polyolefin Resin) The polyolefin resin is not particularly limited as long as it exhibits the effects of the present invention, and conventionally known polyolefin resins can be used. Examples of such polyolefin resins include polyethylene resins, polypropylene resins, polybutene resins, polymethylpentene resins, polybutadiene resins, etc. More specifically, examples include high-density polyethylene, medium-density polyethylene, linear polyethylene, ethylene copolymers with an ethylene content of 50% by weight or more, preferably 70% by weight or more, propylene homopolymers, propylene copolymers with propylene content of 50% by weight or more, preferably 70% by weight or more, butene homopolymers, butene copolymers with a butene content of 50% by weight or more, preferably 70% by weight or more, methylpentene homopolymers, methylpentene copolymers with a methylpentene content of 50% by weight or more, preferably 70% by weight or more, and polybutadiene. If the resin has stereoregularity, it may be isotactic or syndiotactic.

[0027] The copolymer may be a random copolymer or a block copolymer.

[0028] Specific examples of comonomers that can constitute the copolymer include α-olefins having 2 to 12 carbon atoms, such as ethylene, propylene, butene, pentene, hexene, heptene, octene, nonene, decene, undecene, and dodecene; bicyclo-type monomers, such as 1,4-endomethylenecyclohexene; (meth)acrylic acid esters, such as methyl (meth)acrylate and ethyl (meth)acrylate; and vinyl acetate.

[0029] The catalyst used to produce the copolymer may be, of course, a commonly used Ziegler-Natta catalyst, but may also be a catalyst system comprising a combination of a catalyst comprising a transition metal compound (e.g., a titanium halide such as titanium trichloride or titanium tetrachloride) supported on a carrier mainly composed of a magnesium halide such as magnesium chloride and an alkyl aluminum compound (e.g., triethyl aluminum or diethyl aluminum chloride), or a metallocene catalyst.

[0030] The polyolefin resin is preferably a polypropylene resin, more preferably an isotactic homopolypropylene resin. The crystal nucleating agent for polyolefin resins of the present invention can be used in polypropylene resins to preferentially form β crystals.

[0031] The melt flow rate (hereinafter abbreviated as "MFR" according to JIS K 7210-1:2014) of the polyolefin resin is appropriately selected depending on the molding method to be applied, but is preferably about 0.01 to 200 g / 10 min, and more preferably about 0.05 to 100 g / 10 min.

[0032] (Others) The polyolefin resin composition of the present invention may contain additives as needed.

[0033] Examples of the additives include those listed in the "Positive List Additives Handbook" (September 2004) compiled by the Hygienic Association of Polyolefins and Styrene Styrene Styrene etc. Specific examples include fluorescent whitening agents (2,5-thiophenediyl (5-t-butyl-1,3-benzoxazole), 4,4'-bis (benzoxazol-2-yl) stilbene, etc.), antioxidants, stabilizers (metal compounds, epoxy compounds, nitrogen compounds, phosphorus compounds, sulfur compounds, etc.), ultraviolet absorbers (benzophenone compounds, benzotriazole compounds, etc.), surfactants, lubricants (aliphatic hydrocarbons such as paraffin and wax, higher fatty acids having 8 to 22 carbon atoms, higher fatty acid metal salts (Al, Ca, etc.) having 8 to 22 carbon atoms, higher aliphatic alcohols having 8 to 22 carbon atoms, polyglycols, higher fatty acids having 4 to 22 carbon atoms and higher fatty acids having 4 to 18 carbon atoms). Examples of additives include esters with aliphatic monohydric alcohols, higher fatty acid amides having 8 to 22 carbon atoms, silicone oils, rosin derivatives, etc.), fillers (talc, hydrotalcite, mica, zeolite, perlite, diatomaceous earth, calcium carbonate, glass fiber, etc.), foaming agents, foaming aids, polymer additives, plasticizers (dialkyl phthalates, dialkyl hexahydrophthalates, etc.), crosslinking agents, crosslinking accelerators, antistatic agents, flame retardants, dispersants, organic or inorganic pigments (indigo compounds, phthalocyanine compounds, anthraquinone compounds, ultramarine compounds, cobalt aluminate compounds, etc.), processing aids, neutralizing agents, other nucleating agents, and the like.

[0034] The amount of the additive used is preferably, for example, about 0.0001 to 100 parts by mass per 100 parts by mass of the polyolefin resin.

[0035] (Production Method) The production method of the polyolefin resin composition of the present invention is not limited to this, and for example, a polyolefin resin crystal nucleating agent and additives are added to the polyolefin resin, and the mixture is dry-blended in a Henschel mixer. Then, the mixture is melt-kneaded and extruded using an extruder (e.g., 15 mmφ, L / D=45) at a resin temperature of 200°C and a rotation speed of 250 rpm. The resulting strand is water-cooled, cut, and pelletized.

[0036] <Polyolefin Resin Molded Article> The polyolefin resin molded article of the present invention is made from the above-described polyolefin resin composition.

[0037] The polyolefin resin molded article of the present invention can be obtained by molding the polyolefin resin composition of the present invention according to a general molding method. The molding method is not particularly limited as long as it can achieve the effects of the present invention, and any of the conventionally known molding methods such as injection molding, extrusion molding, blow molding, pressure molding, rotational molding, and film molding can be used.

[0038] The polyolefin resin molded article of the present invention has a high crystallization temperature. Specifically, the crystallization temperature of the polyolefin resin molded article of the present invention can be 126° C. or higher. The crystallization temperature is preferably 126.5° C. or higher, and more preferably 127° C. or higher.

[0039] The crystallization temperature can be measured using a differential scanning calorimeter (DSC8500, manufactured by PerkinElmer) in accordance with JIS K7121:2012. Specifically, 6 mg of a polyolefin resin molded product obtained by injection molding is used. The measurement conditions are as follows: the product is held at 200°C for 3 minutes in a helium atmosphere, and then cooled to 50°C at a rate of 10°C / min. The apex of the exothermic peak obtained at this time is taken as the crystallization temperature (°C).

[0040] The polyolefin resin molded article of the present invention is preferably a polypropylene resin molded article. When a polyolefin resin crystal nucleating agent containing zinc 3,4,5,6-tetrahydrophthalate is used, the polypropylene resin molded article can have a high β-crystal content. Specifically, the β-crystal content can be 30% or more. The β-crystal content is preferably 70% or more, more preferably 80% or more, and even more preferably 85% or more.

[0041] The β-crystal content can be measured using a differential scanning calorimeter (DSC8500, manufactured by PerkinElmer) in accordance with JIS K7121:2012. Specifically, 6 mg of a polyolefin-based resin molded body (polypropylene-based resin molded body) obtained by injection molding is used. The measurement conditions are as follows: the temperature is maintained at 200°C for 3 minutes under a helium atmosphere, then the temperature is lowered to 50°C at 10°C / min, and then the temperature is raised to 200°C at 20°C / min. Based on the peak areas of the α-crystal and β-crystal endothermic peaks obtained at this time, the β-crystal content (%) is calculated by the formula: <[(β-crystal peak area) ÷ (α-crystal peak area + β-crystal peak area)] × 100>.

[0042] The present specification discloses the following. Disclosure (1) is a 3,4,5,6-tetrahydrophthalic acid metal salt. Disclosure (2) is a 3,4,5,6-tetrahydrophthalic acid metal salt according to Disclosure (1), in which the metal salt is a monovalent or divalent metal salt. Disclosure (3) is a 3,4,5,6-tetrahydrophthalic acid metal salt according to Disclosure (2), in which the metal salt is a zinc salt. Disclosure (4) is a crystal nucleating agent for polyolefin-based resins containing a 3,4,5,6-tetrahydrophthalic acid metal salt. Disclosure (5) is a crystal nucleating agent for polyolefin-based resins according to Disclosure (4), in which the metal salt is a monovalent or divalent metal salt. Disclosure (6) is a crystal nucleating agent for polyolefin-based resins according to Disclosure (5), in which the metal salt is a zinc salt. The present disclosure (7) is a polyolefin-based resin composition comprising the crystal nucleating agent for polyolefin-based resins according to the present disclosure (6) and a polyolefin-based resin. The present disclosure (8) is the polyolefin-based resin composition according to the present disclosure (7), in which the content of a metal salt of 3,4,5,6-tetrahydrophthalic acid in the polyolefin-based resin composition is 100 ppm or more. The present disclosure (9) is the polyolefin-based resin composition according to the present disclosure (7) or (8), in which the polyolefin-based resin is a polypropylene-based resin. The present disclosure (10) is a polyolefin-based resin molded article made from the polyolefin-based resin composition according to the present disclosure (9), and having a β-crystal content of 30% or more. The present disclosure (11) is the crystal nucleating agent for polyolefin-based resins according to the present disclosure (5), in which the metal salt is a sodium salt or a calcium salt. The present disclosure (12) is a polyolefin-based resin composition comprising the crystal nucleating agent for polyolefin-based resins according to the present disclosure (11) and a polyolefin-based resin. The present disclosure (13) is the polyolefin-based resin composition according to the present disclosure (12), wherein the content of the metal salt of 3,4,5,6-tetrahydrophthalic acid in the polyolefin-based resin composition is 100 ppm or more. The present disclosure (14) is the polyolefin-based resin composition according to the present disclosure (12) or (13), wherein the polyolefin-based resin is a polypropylene-based resin.The present disclosure (15) is a polyolefin resin molded article made of the polyolefin resin composition according to any one of the present disclosures (7) to (9) and (12) to (14), having a crystallization temperature of 126°C or higher.

[0043] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Reagents were used for compounds not specifically mentioned.

[0044] <Crystal Nucleating Agent for Polyolefin Resin> A crystal nucleating agent for polyolefin resin was prepared by the following method.

[0045] (N-1): Zinc 3,4,5,6-tetrahydrophthalate 3,4,5,6-tetrahydrophthalic anhydride (reagent, manufactured by TCI) was ring-opened and neutralized with an aqueous solution of sodium hydroxide to prepare disodium 3,4,5,6-tetrahydrophthalate. Disodium 3,4,5,6-tetrahydrophthalate was then reacted with an aqueous solution of zinc chloride (reagent, manufactured by TCI) to obtain zinc 3,4,5,6-tetrahydrophthalate.

[0046] (N-2): 3,4,5,6-tetrahydrophthalic acid disodium salt 3,4,5,6-Tetrahydrophthalic anhydride (reagent, manufactured by TIC) was ring-opened and neutralized with an aqueous sodium hydroxide solution. Acetone was then added to the resulting aqueous solution, and the precipitated white solid was filtered and dried to obtain 3,4,5,6-tetrahydrophthalic acid disodium salt.

[0047] (N-3): Calcium 3,4,5,6-tetrahydrophthalate 3,4,5,6-tetrahydrophthalic anhydride (reagent, manufactured by TCI) was ring-opened and neutralized with an aqueous solution of sodium hydroxide to prepare disodium 3,4,5,6-tetrahydrophthalate. Disodium 3,4,5,6-tetrahydrophthalate was then reacted with an aqueous solution of calcium chloride (reagent, manufactured by TCI) to obtain calcium 3,4,5,6-tetrahydrophthalate.

[0048] (N-4): 3,4,5,6-tetrahydrophthalic acid dilithium salt 3,4,5,6-Tetrahydrophthalic anhydride (reagent, manufactured by TIC) was ring-opened and neutralized with an aqueous solution of lithium hydroxide. Acetone was then added to the resulting aqueous solution, and the precipitated white solid was filtered and dried to obtain 3,4,5,6-tetrahydrophthalic acid dilithium salt.

[0049] (N-5): 1,2,3,6-tetrahydrophthalic acid calcium salt 1,2,3,6-Tetrahydrophthalic anhydride (reagent, manufactured by TCI) was ring-opened and neutralized with an aqueous solution of sodium hydroxide to prepare disodium 1,2,3,6-tetrahydrophthalate. Next, disodium 1,2,3,6-tetrahydrophthalate was reacted with an aqueous solution of calcium chloride (reagent, manufactured by TCI) to obtain calcium 1,2,3,6-tetrahydrophthalate.

[0050] (N-6): Sodium salt of benzoic acid Commercially available sodium salt of benzoic acid was prepared.

[0051] <Polyolefin-based resin> The following polyolefin-based resins were prepared: (P-1) Isotactic homopolypropylene (MFR = 30 g / 10 min) (P-2) Isotactic homopolypropylene (MFR = 7 g / 10 min) The MFR of the polyolefin-based resins was measured based on JIS K 7210-1:2014.

[0052] Example 1 Preparation of Polyolefin Resin Composition A crystal nucleating agent (N-1) for polyolefin resins was added to an isotactic homopolypropylene resin (P-1) in an amount shown in Table 1, and 0.05 parts by mass of calcium stearate, 0.05 parts by mass of tetrakis[methylene-2-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane (trade name Irganox (registered trademark) 1010, manufactured by BASF), and 0.05 parts by mass of tris(2,4-di-tert-butylphenyl)phosphite (trade name Irgafos (registered trademark) 168, manufactured by BASF) were further compounded relative to 100 parts by mass of (P-1), and the mixture was dry-blended using a Henschel mixer. Next, the mixture was melt-kneaded and extruded using an extruder (15 mmφ, L / D=45) at a resin temperature of 200°C and a rotation speed of 250 rpm. The resulting strand was water-cooled, cut, and pelletized to obtain a polyolefin resin composition.

[0053] <Preparation of polyolefin-based resin molded body (polypropylene-based resin molded body)> The obtained polyolefin-based resin composition was injection molded under conditions of a resin temperature of 200°C and a mold temperature of 40°C to obtain a polyolefin-based resin molded body (test piece) in the form of a corrugated plate having a thickness of 0.5 / 1.0 mm.

[0054] (Examples 2 to 8, Comparative Examples 1 and 2) Polyolefin resin compositions and polyolefin resin molded articles were prepared in the same manner as in Example 1, except that the type and amount of the nucleating agent for polyolefin resins was changed as shown in Table 1. In the table, "nucleating agent for polyolefin resins" is abbreviated to "nucleating agent."

[0055] Example 9 A polyolefin resin composition and a polyolefin resin molded article were prepared in the same manner as in Example 1, except that the isotactic homopolypropylene resin (P-1) was changed to the isotactic homopolypropylene resin (P-2).

[0056] (Examples 10 to 12, Comparative Examples 3 and 4) Polyolefin resin compositions and polyolefin resin molded articles were prepared in the same manner as in Example 9, except that the type and amount of the crystal nucleating agent for polyolefin resins were changed as shown in Table 2.

[0057] <Evaluation of β-crystal formability> Measurement was performed using a differential scanning calorimeter (DSC8500, manufactured by PerkinElmer) according to JIS K7121:2012 using the following method. 6 mg of the obtained polyolefin resin molded product was used, and the measurement conditions were as follows: it was held at 200°C for 3 minutes under a helium atmosphere, then cooled to 50°C at 10°C / min, and then heated to 200°C at 20°C / min. Based on the peak areas of the α-crystal and β-crystal endothermic peaks obtained at this time, the β-crystal content (%) was calculated by [(β-crystal peak area) ÷ (α-crystal peak area + β-crystal peak area)] × 100, and evaluated according to the following criteria. A β-crystal content of 0% indicates that α-crystals were formed. (Evaluation criteria) ⊚: The β-crystal content was 70% or more. ◯: The β-crystal content was 30% or more but less than 70%. ×: The β-crystal content was less than 30%.

[0058] <Evaluation of Crystallization Temperature> Measurement was performed using a differential scanning calorimeter (DSC8500, manufactured by PerkinElmer) according to the following method in accordance with JIS K7121:2012. 6 mg of the obtained polyolefin resin molded product was used, and the measurement conditions were that the product was held at 200°C for 3 minutes in a helium atmosphere, and then cooled to 50°C at a rate of 10°C / min. The apex of the exothermic peak obtained at this time was taken as the crystallization temperature (°C), and the crystallization temperature was evaluated according to the following criteria. (Evaluation criteria) ◯: The crystallization temperature was 126°C or higher. ×: The crystallization temperature was lower than 126°C.

[0059]

[0060]

[0061] The above examples confirmed that the polyolefin resin nucleating agent of the present invention can improve the crystallization temperature of polyolefin resin molded articles. Furthermore, the examples using nucleating agent N-1 confirmed that the polyolefin resin nucleating agent containing zinc 3,4,5,6-tetrahydrophthalate has excellent β-crystal forming ability.

[0062] The present invention provides a crystal nucleating agent for polyolefin resins that can improve the crystallization temperature of polyolefin resin molded articles. The present invention also provides a metal salt of 3,4,5,6-tetrahydrophthalic acid that can be used as the polyolefin crystal nucleating agent, a polyolefin resin composition using the polyolefin resin crystal nucleating agent, and a polyolefin resin molded article.

Claims

1. 3,4,5,6-tetrahydrophthalic acid metal salts.

2. The 3,4,5,6-tetrahydrophthalic acid metal salt according to claim 1, wherein the metal salt is a monovalent or divalent metal salt.

3. The metal salt of 3,4,5,6-tetrahydrophthalic acid according to claim 2, wherein the metal salt is a zinc salt.

4. A crystal nucleating agent for polyolefin resins containing a metal salt of 3,4,5,6-tetrahydrophthalic acid.

5. The crystal nucleating agent for polyolefin resins according to claim 4, wherein the metal salt is a monovalent or divalent metal salt.

6. A crystal nucleating agent for polyolefin resins according to claim 5, wherein the metal salt is a zinc salt.

7. A polyolefin resin composition comprising the crystal nucleating agent for polyolefin resins according to claim 6 and a polyolefin resin.

8. The polyolefin resin composition according to claim 7, wherein the content of the metal salt of 3,4,5,6-tetrahydrophthalic acid in the polyolefin resin composition is 100 ppm or more.

9. The polyolefin resin composition according to claim 7, wherein the polyolefin resin is a polypropylene resin.

10. A polyolefin resin molded article made from the polyolefin resin composition according to claim 9, having a β crystal content of 30% or more.

11. The crystal nucleating agent for polyolefin resins according to claim 5, wherein the metal salt is a sodium salt or a calcium salt.

12. A polyolefin resin composition comprising the crystal nucleating agent for polyolefin resins according to claim 11 and a polyolefin resin.

13. The polyolefin resin composition according to claim 12, wherein the content of the metal salt of 3,4,5,6-tetrahydrophthalic acid in the polyolefin resin composition is 100 ppm or more.

14. The polyolefin resin composition according to claim 12, wherein the polyolefin resin is a polypropylene resin.

15. A polyolefin resin molded article made from the polyolefin resin composition according to claim 9 or 14, having a crystallization temperature of 126°C or higher.

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