Resin composition

Abstract

To provide a syndiotactic polystyrene-based resin composition that exhibits excellent moldability and produces a molded article having high transparency.SOLUTION: A resin composition comprises polystyrene (A) with a syndiotactic structure as a main component, wherein a melt viscoelasticity (tanδ) is 7.7 or less at an angular frequency of 1 rad / s, and styrenic resin accounts for over 80 mass% of the composition.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a resin composition and an extrusion molded product. [Background technology]

[0002] Polystyrene having a syndiotactic structure can achieve a high degree of crystallinity, and therefore sheets obtained therefrom have excellent heat resistance and chemical resistance and are used as various molded articles such as containers, etc. For example, Patent Document 1 discloses a film obtained using a resin composition containing syndiotactic polystyrene as a main component (hereinafter also referred to as a "syndiotactic polystyrene-based resin composition"). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-268117 Summary of the Invention [Problem to be solved by the invention]

[0004] Although syndiotactic polystyrene resin compositions are excellent in various properties, further improvements have been desired. An object of the present invention is to provide a syndiotactic polystyrene resin composition which can realize a molded article having high transparency and has excellent moldability. [Means for solving the problem]

[0005] According to the present invention, the following resin composition and the like are provided. 1. The main component is polystyrene (A) having a syndiotactic structure, The melt viscoelasticity (tan δ) at an angular frequency of 1 rad / s is 7.7 or less, More than 80% by mass is a styrene-based resin; Resin composition. 2. The resin composition according to 1, comprising polystyrene (B) having a melt viscoelasticity (tan δ) of 7.7 or less at an angular frequency of 1 rad / s. 3. The resin composition according to 2, wherein the polystyrene (B) is a hyperbranched polystyrene. 4. The resin composition according to any one of 1 to 3, which contains a rubber-like elastomer (C). 5. The resin composition according to any one of 1 to 4, wherein the polyethylene content is less than 20 mass %. 6. The resin composition according to any one of 1 to 5, which is for extrusion molding. 7. The resin composition according to any one of 1 to 6, which is for use in inflation molding or extrusion lamination. 8. An extrusion molded product obtained from the resin composition according to any one of 1 to 7. Effect of the Invention

[0006] According to the present invention, it is possible to provide a syndiotactic polystyrene resin composition which can realize a molded article having high transparency and has excellent moldability. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] The resin composition and extrusion molded product of the present invention will be described in detail below. In this specification, "x to y" represents a numerical range of "x or more, y or less". The upper and lower limit values ​​described for the numerical ranges can be combined in any way. In addition, a combination of two or more of the individual embodiments of the present invention described below is also an embodiment of the present invention. In addition, a numerical range of "x or more" implies "greater than x", and a numerical range of "y or less" implies "less than y".

[0008] [Resin composition] The resin composition according to one embodiment of the present invention is mainly composed of polystyrene (A) having a syndiotactic structure, and has a melt viscoelasticity (tan δ) of 7.7 or less at an angular frequency of 1 rad / s. The resin composition contains more than 80 mass% of a styrene-based resin.

[0009] (Melt viscoelasticity (tan δ)) Many resin materials have both elastic and viscous properties (viscoelasticity), and the ratio of these properties varies from material to material. As an index showing which of these properties is more strongly expressed, "melt viscoelasticity" (loss tangent: tan δ) is used, which is the degree of viscosity (dynamic loss modulus) divided by the degree of elasticity (dynamic storage modulus), and the higher the melt viscoelasticity, the higher the viscosity. Melt viscoelasticity depends on the speed at which the resin material is deformed, but the present inventors focused on melt viscoelasticity at a relatively slow deformation speed of an angular frequency of 1 rad / s, and found that when the melt viscoelasticity is within a specific range, a syndiotactic polystyrene-based resin composition exhibits excellent molding processability, thereby completing the present invention.

[0010] The resin composition according to one embodiment of the present invention has a melt viscoelasticity (tan δ) of 7.7 or less at an angular frequency of 1 rad / s, and therefore exhibits excellent moldability. Specifically, when subjected to various extrusion molding methods (particularly, inflation molding and extrusion lamination), the resin composition exhibits an ideal stretching mode, and a uniform sheet (film) can be obtained. The melt viscoelasticity (tan δ) at an angular frequency of 1 rad / s is preferably 7.7 or less, more preferably 7.4 or less, even more preferably 7.1 or less, and even more preferably 6.8 or less. The lower limit of the melt viscoelasticity (tan δ) is not particularly limited, but may be, for example, 0.1 or more or 1.0 or more.

[0011] The melt viscoelasticity of the resin composition is a value at an angular frequency of 1 rad / s measured at [the melting point of the resin composition rounded off to the nearest whole number + 20]° C. Specific methods for measuring the melt viscoelasticity and melting point are as described in the Examples.

[0012] Each component of the resin composition will be described below.

[0013] (Polystyrene having a syndiotactic structure (A)) Polystyrene having a syndiotactic structure (hereinafter also referred to as simply "syndiotactic polystyrene", "SPS (A)" or "component (A)") is a crystalline styrene-based resin having a high degree of syndiotactic structure. "Syndiotactic" means that there is a high proportion of phenyl rings in adjacent styrene units that are arranged alternately with respect to the plane formed by the main chain of the polymer block (hereinafter referred to as syndiotacticity).

[0014] Tacticity is a method to measure the molecular dynamics of the nucleus by using isotope carbon ( 13 Quantitative identification can be performed using the C-NMR method. 13 By C-NMR, the proportion of consecutive multiple structural units, for example, two consecutive monomer units as a diad, three consecutive monomer units as a triad, and five consecutive monomer units as a pentad, can be quantified.

[0015] The term "styrene resin having a highly syndiotactic structure" refers to a styrene polymer such as polystyrene, poly(hydrocarbon-substituted styrene), poly(halogenated styrene), poly(halogenated alkylstyrene), poly(alkoxystyrene), poly(vinyl benzoate), etc., having a syndiotacticity of usually 75 mol % or more, preferably 85 mol % or more in racemic diad (r), or usually 30 mol % or more, preferably 50 mol % or more in racemic pentad (rrrr), a hydrogenated polymer or mixture of these, or a copolymer having these as the main component.

[0016] Examples of poly(hydrocarbon-substituted styrenes) include poly(methylstyrene), poly(ethylstyrene), poly(isopropylstyrene), poly(tert-butylstyrene), poly(phenylstyrene), poly(vinylnaphthalene), and poly(vinylstyrene). Examples of poly(halogenated styrenes) include poly(chlorostyrene), poly(bromostyrene), and poly(fluorostyrene), and examples of poly(halogenated alkylstyrenes) include poly(chloromethylstyrene). Examples of poly(alkoxystyrenes) include poly(methoxystyrene) and poly(ethoxystyrene).

[0017] Comonomer components of copolymers containing the above structural units include, in addition to the monomers of the above styrene-based polymers, olefin monomers such as ethylene, propylene, butene, hexene, and octene; diene monomers such as butadiene and isoprene; and polar vinyl monomers such as cyclic olefin monomers, cyclic diene monomers, methyl methacrylate, maleic anhydride, and acrylonitrile. Examples of the copolymer that can be suitably used include a copolymer of styrene and p-methylstyrene, a copolymer of styrene and p-tert-butylstyrene, a copolymer of styrene and divinylbenzene, and the like, with a copolymer of styrene and p-methylstyrene being preferred.

[0018] Among the syndiotactic polystyrenes, one or more selected from polystyrene, poly(p-methylstyrene), poly(m-methylstyrene), poly(p-tert-butylstyrene), poly(p-chlorostyrene), poly(m-chlorostyrene), poly(p-fluorostyrene), and a copolymer of styrene and p-methylstyrene are preferred, one or more selected from polystyrene, poly(p-methylstyrene), poly(m-methylstyrene), and a copolymer of styrene and p-methylstyrene are more preferred, polystyrene and a copolymer of styrene and p-methylstyrene are even more preferred, and polystyrene is the most preferred.

[0019] The melt flow rate (MFR) of the syndiotactic polystyrene is preferably 1 g / 10 min or more, more preferably 2 g / 10 min or more, even more preferably 3 g / 10 min or more or 4 g / 10 min or more. Also, it is preferably 40 g / 10 min or less, more preferably 25 g / 10 min or less, even more preferably 18 g / 10 min or less. If the MFR is 1 g / 10 min or more, there is no problem with the flowability of the resin during extrusion molding, and if it is 40 g / 10 min or less, preferably 20 g / 10 min or less, a molded product having sufficient strength can be obtained. The MFR measurement of syndiotactic polystyrene is carried out under conditions of a temperature of 300°C and a load of 1.2 kg.

[0020] The weight average molecular weight of the syndiotactic polystyrene is preferably 100,000 or more, more preferably 110,000 or more, even more preferably 130,000 or more, or 150,000 or more. Within such a range, the film formability and strength are excellent. Furthermore, the weight average molecular weight of the syndiotactic polystyrene is preferably 500,000 or less, more preferably 350,000 or less, even more preferably 300,000 or less. Within such a range, the fluidity of the resin during extrusion molding can be ensured. The weight average molecular weight of syndiotactic polystyrene is a value measured by gel permeation chromatography at 145° C. using 1,2,4-trichlorobenzene as a solvent, and converted using a calibration curve of standard polystyrene.

[0021] Syndiotactic polystyrene can be produced by known methods, for example, by polymerizing a styrene monomer in an inert hydrocarbon solvent or in the absence of a solvent using a condensation product of a titanium compound, water, and trialkylaluminum as a catalyst.

[0022] "Containing polystyrene (A) having a syndiotactic structure as the main component" means that more than 50 mass% of the resin composition is syndiotactic polystyrene. By using syndiotactic polystyrene as the main component, it is possible to realize excellent heat resistance and chemical resistance when molded into a molded product. The content of component (A) in the resin composition according to one embodiment of the present invention is, for example, 55% by mass or more, 60% by mass or more, 65% by mass or more, 70% by mass or more, 75% by mass or more, or 80% by mass or more. There is no particular upper limit, but it is, for example, 99% by mass or less, 95% by mass or less, or 90% by mass or less. The content of component (A) in the resin composition according to one embodiment of the present invention is, for example, more than 50 mass % and not more than 99 mass %, more than 50 mass % and not more than 95 mass %, or more than 50 mass % and not more than 90 mass %.

[0023] (Polystyrene (B) exhibiting a specific melt viscoelasticity (tan δ)) The resin composition according to one embodiment of the present invention preferably contains polystyrene (B) having a melt viscoelasticity (tan δ) of 7.7 or less at an angular frequency of 1 rad / s (hereinafter also simply referred to as “polystyrene (B)” or “component (B)”).

[0024] Polystyrene (B) is a material with a lower melt viscoelasticity (tan δ) at an angular frequency of 1 rad / s compared to ordinary polystyrene, and by including such a component, the melt viscoelasticity of the resin composition at an angular frequency of 1 rad / s can be easily controlled within a specific range. This effect is believed to be due to the high degree of molecular entanglement that occurs between components (A) and (B). In addition, since component (B) is a styrene-based resin like component (A), various effects can be obtained. First, the difference in refractive index between the components is small, making it possible to realize a molded product with high transparency. Second, component (A) is not highly compatible with other thermoplastic resins (e.g., polyethylene), and mixing may be difficult unless a compatibilizer is used. However, component (B) is highly compatible with component (A), so a compatibilizer is not necessary or only a very small amount is required. Furthermore, for the same reason, the above effects can be obtained sufficiently even with the addition of a small amount of component (B).

[0025] The polystyrene (B) may be a crystalline resin or an amorphous resin.

[0026] The melt viscoelasticity (tan δ) of component (B) at an angular frequency of 1 rad / s is preferably 2.0 to 7.7. When the melt viscoelasticity is 2.0 or more, compatibility with component (A) is easily obtained, and when the melt viscoelasticity is 7.7 or less, suitability for extrusion processing is easily imparted, specifically, bubble stability and film thickness accuracy during inflation molding can be improved, and neck-in stability during extrusion lamination molding is excellent.

[0027] The melt viscoelasticity (tan δ) of component (B) is a value measured at [the melting point of the resin rounded off to the nearest 1 + 20]°C when component (B) is a crystalline resin, and is a value measured at 270°C when component (B) is an amorphous resin. A crystalline resin refers to a resin that has a clear melting point, specifically, a resin that shows a clear endothermic peak when measured by the method for measuring the "melting point of the resin composition" described in the Examples. Amorphous resin refers to a resin that does not have a clear melting point, specifically, a resin that does not show a clear endothermic peak when measured by the method for measuring the "melting point of the resin composition" described in the Examples. Other measurement conditions for the melt viscoelasticity (tan δ) of component (B) are the same as those for the resin composition described above, and specific measurement conditions (including melting point) other than the measurement temperature are as described in the Examples.

[0028] As the polystyrene (B), for example, hyperbranched polystyrene (B1) can be used.

[0029] Examples of the hyperbranched polystyrene (B1) (hereinafter also simply referred to as "component (B1)") include polymers obtained by copolymerizing a macromonomer having a plurality of polymerizable double bonds with a styrene-based monomer.

[0030] Examples of the macromonomer include a multifunctional polyester (meth)acrylate having polymerizable double bonds at multiple molecular ends, a multifunctional polyether (meth)acrylate having polymerizable double bonds at multiple molecular ends, a multifunctional polyurethane (meth)acrylate having polymerizable double bonds at multiple molecular ends, and divinylbenzene.

[0031] Examples of styrene-based monomers include styrene and derivatives thereof. For example, alkyl styrenes such as styrene, methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, propylstyrene, butylstyrene, hexylstyrene, heptylstyrene, and octylstyrene; halogenated styrenes such as fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, and iodostyrene; and others such as nitrostyrene, acetylstyrene, and methoxystyrene. These may be used alone or in combination of two or more. The hyperbranched polystyrene may have a syndiotactic, isotactic, or atactic structure.

[0032] As the hyperbranched polystyrene (B1), crosslinked polystyrene in which a crosslinked structure is introduced by reactive extrusion using a peroxide or electron beam irradiation can also be used.

[0033] The molecular weight of component (B) is not particularly limited, but the weight average molecular weight is, for example, 100,000 to 40,000, and preferably 12,000 to 300,000. This provides excellent extrusion moldability. The weight average molecular weight of component (B) is measured by gel permeation chromatography at 145°C using 1,2,4-trichlorobenzene as a solvent, and converted using a calibration curve of standard polystyrene.

[0034] The melt flow rate (MFR) of the component (B) is not particularly limited. In one embodiment, the MFR of the hyperbranched polystyrene is 0.5 to 15.0 g / 10 min, and preferably 0.7 to 8.0 g / 10 min, which makes it easier to impart extrusion processability, specifically, improves bubble stability and film thickness accuracy during inflation molding, and provides excellent neck-in stability during extrusion lamination molding. The MFR of component (B) is measured in accordance with JIS K7210 under conditions of a temperature of 200°C and a load of 5 kg.

[0035] By definition, component (B2) may overlap with the above-mentioned component (A), but these are separate components, and anything that falls under component (A) will be treated as component (A).

[0036] When the resin composition according to one embodiment of the present invention contains component (B), the content thereof is, for example, 1% by mass or more, 3% by mass or more, or 5% by mass or more. It may also be, for example, 7% by mass or more, 10% by mass or more, 15% by mass or more, 20% by mass or more, or 25% by mass or more. There is no particular upper limit, but it is, for example, 40% by mass or less, 35% by mass or less, or 30% by mass or less. It may also be, for example, 25% by mass or less, 20% by mass or less, 15% by mass or less, or 10% by mass or less. The component (B) may be one of the above-mentioned compounds or a combination of two or more of them, and the above content is the total amount of the component (B).

[0037] (Rubber-like elastomer (C)) The resin composition according to one embodiment of the present invention may or may not contain a rubber-like elastomer (hereinafter, also simply referred to as "component (C)"). When the resin composition contains the rubber-like elastomer (C), toughness can be improved. Various rubber-like elastomers can be used, but preferably they are elastomers containing structural units derived from styrene, such as at least one selected from the group consisting of styrene-diene block copolymers, hydrogenated styrene-diene block copolymers, styrene-diene random copolymers, hydrogenated styrene-diene random copolymers, and styrene-olefin random copolymers. Examples of dienes copolymerized with styrene include butadiene and isoprene, and examples of olefins copolymerized with styrene include ethylene, propylene, and butylene.

[0038] The rubber-like elastomer (C) is more preferably at least one selected from the group consisting of styrene-butadiene block copolymer (SBR), hydrogenated styrene-butadiene block copolymer (SEB), styrene-butadiene-styrene block copolymer (SBS), hydrogenated styrene-butadiene-styrene block copolymer (SEBS), styrene-isoprene block copolymer (SIR), hydrogenated styrene-isoprene block copolymer (SEP), styrene-isoprene-styrene block copolymer (SIS), hydrogenated styrene-isoprene-styrene block copolymer (SEPS), styrene-butadiene random copolymer, hydrogenated styrene-butadiene random copolymer, styrene-ethylene-propylene random copolymer, and styrene-ethylene-butylene random copolymer, and is further preferably at least one selected from the group consisting of styrene-butadiene block copolymer (SBR), hydrogenated styrene-butadiene block copolymer (SEB), styrene-butadiene-styrene block copolymer (SBS), hydrogenated styrene-butadiene-styrene block copolymer (S The rubber-like elastomer is at least one selected from the group consisting of styrene-butadiene-styrene block copolymer (SBS), hydrogenated styrene-isoprene block copolymer (SEP), styrene-isoprene-styrene block copolymer (SIS), and hydrogenated styrene-isoprene-styrene block copolymer (SEPS), and more preferably at least one selected from the group consisting of styrene-butadiene-styrene block copolymer (SBS), hydrogenated styrene-butadiene-styrene block copolymer (SEBS), styrene-isoprene-styrene block copolymer (SIS), and hydrogenated styrene-isoprene-styrene block copolymer (SEPS), and more preferably at least one selected from the group consisting of hydrogenated styrene-butadiene-styrene block copolymer (SEBS), styrene-isoprene-styrene block copolymer (SIS), and hydrogenated styrene-isoprene-styrene block copolymer (SEPS), and more preferably hydrogenated styrene-butadiene-styrene block copolymer (SEBS). The rubber-like elastomer may be any one of the above or a combination of two or more.The rubber elastic material may be one that has been chemically modified, for example, with maleic acid.

[0039] The mass ratio of the structural units derived from styrene to the total of the structural units derived from diene, hydrogenated diene and olefin constituting the rubber-like elastomer (C) [(styrene) / (diene, hydrogenated diene, olefin)] is preferably 20 / 80 to 70 / 30, and may be 25 / 75 to 60 / 40, or 25 / 75 to 45 / 55. The styrene content of the rubber-like elastomer (C) is preferably in the range of 25 to 60% by mass, and may be 25 to 45%. By setting the mass ratio in this way, the compatibility with SPS (A) can be further improved, and toughness can be improved while maintaining heat resistance and dimensional stability at high temperatures.

[0040] The melt flow rate (MFR) of the rubber-like elastomer (C) is preferably 0.0 g / 10 min or more and 30 g / 10 min or less, in which case the toughness improving effect is excellent. The MFR measurement of the rubber-like elastomer (C) is carried out under conditions of a temperature of 230° C. and a load of 2.16 kg.

[0041] When the resin composition according to one aspect of the present invention contains the component (C), the content thereof is, for example, 1 mass% or more, 3 mass% or more, 5 mass% or more, or 7 mass% or more. There is no particular upper limit, but it is, for example, 30 mass% or less, 20 mass% or less, or 15 mass% or less.

[0042] (Other resins (D), etc.) The resin composition according to one embodiment of the present invention may or may not contain a resin component other than the above-mentioned components (A) to (C) (hereinafter also simply referred to as "component (D)") and various additives. Resins other than components (A) to (C) include polystyrene having an atactic structure (aPS), high impact polystyrene (HIPS), polyphenylene ether, other thermoplastic resins, etc. By definition, any of the above-mentioned components (A) to (C) is treated as any of components (A) to (C). As the aPS, for example, polystyrene having a weight-average molecular weight larger than that of ordinary polystyrene (weight-average molecular weight of, for example, 100,000 to 1 million) may be used.

[0043] When the resin composition according to one aspect of the present invention contains the component (D), the content thereof is, for example, 1 mass % or more, 3 mass % or more, or 5 mass % or more. There is no particular upper limit, but it is, for example, 40 mass % or less, or 20 mass % or less. In one embodiment, the resin composition does not include component (D).

[0044] Examples of the additives include stabilizers (heat stabilizers, antioxidants), ultraviolet absorbers, antiblocking agents, lubricants, colorants, and antistatic agents.

[0045] When the resin composition according to one aspect of the present invention contains the additive, the content thereof is, for example, 0.1% by mass or more, 0.5% by mass or more, or 1% by mass or more. There is no particular upper limit, but it is, for example, 5% by mass or less, or 3% by mass or less.

[0046] (Resin composition) The resin composition according to one embodiment of the present invention contains a styrene-based resin in an amount of more than 80% by mass, which makes it possible to realize a molded article having high transparency. A styrene-based resin refers to a resin that contains a styrene-derived moiety as a monomer unit, and includes polystyrene having an atactic structure, polystyrene having an isotactic structure, syndiotactic polystyrene, hyperbranched polystyrene, elastomers containing structural units derived from styrene, and high impact polystyrene (HIPS). The resin composition according to one embodiment of the present invention is, for example, more than 82 mass%, 85 mass% or more, 87 mass% or more, 90 mass% or more, 95 mass% or more, 98 mass% or more, 99 mass% or more, 99.9 mass% or more, or 100 mass% is a styrene-based resin.

[0047] The resin composition according to one embodiment of the present invention may be, for example, 80% by mass or more, 85% by mass or more, 87% by mass or more, 90% by mass or more, 95% by mass or more, 98% by mass or more, 99% by mass or more, 99.9% by mass or more, or 100% by mass of Component (A) and component (B), Component (A), component (B), and additives; Component (A), component (B), and component (C), Component (A), component (B), component (C), and an additive; Component (A), component (B), component (C), and component (D), or Component (A), component (B), component (C), component (D), and additives may be also possible.

[0048] In a resin composition according to one embodiment of the present invention, the proportion of thermoplastic resins other than polystyrene is, for example, 20% by mass or less, 15% by mass or less, 10% by mass or less, 5% by mass or less, 3% by mass or less, 1% by mass or less, 0.1% by mass or less, or 0% by mass. The term "thermoplastic resin other than polystyrene" refers to a thermoplastic resin other than polystyrene and rubber-like elastomers, and examples thereof include polyethylene.

[0049] [Application] The resin composition according to one embodiment of the present invention can be used in various extrusion molding methods, and can be suitably used for, for example, inflation molding, extrusion lamination, blow molding (direct blow), or foam molding such as extrusion foaming. Known methods can be used for these methods. When subjecting the composition to various extrusion molding methods, the components may be mixed in advance to form a resin composition, which is then fed into an extrusion molding machine, or some or all of the components may be fed, for example, in the form of pellets into an extrusion molding machine and molded.

[0050] [Extrusion moldings, etc.] The extrusion molded product according to one embodiment of the present invention is a molded product obtained by melt-extruding the resin composition according to one embodiment of the present invention described above. The shape of the extrusion molding is not particularly limited, and may be, for example, a sheet shape, a film shape, or a fiber shape. It may also be a laminate of a layer obtained from the resin composition and another layer. Examples of the other layer include a substrate layer that serves as the base of the laminate, an adhesive layer for interlayer adhesion, a printing layer for decoration, a release layer, etc., and an appropriate configuration can be adopted according to the application.

[0051] The sheet (film) obtained from the above resin composition, or the above-mentioned laminate, can be used as packaging materials such as vegetable packaging, twist packaging, pharmaceutical packaging materials, reagent containers (packaging materials, flexible containers), food containers, food container surface base materials, food container lids, heat-resistant cooking films, instant noodle container surface materials, adhesive labels, simple adhesive tapes, and other packaging materials; and industrial materials such as masking films, labels, magazine tapes, release films, insulating films, chemical-resistant films, paper laminates, printed circuit board base materials, films for film capacitors, component trays, nonwoven fabrics, packaging materials for household holdings, agricultural materials, and battery-related materials. Furthermore, by thermoforming a sheet (film) obtained from the above-mentioned resin composition or the above-mentioned laminate, various molded articles such as containers can be produced. The thermoforming method is not particularly limited, and examples thereof include vacuum forming and hot plate compression forming. EXAMPLES

[0052] Examples of the present invention will be described below, but the present invention is not limited to these examples.

[0053] [Ingredients used] The materials used in the following examples and comparative examples are as follows. (Polystyrene having a syndiotactic structure (A)) SPS1: syndiotactic polystyrene, manufactured by Idemitsu Kosan Co., Ltd., MFR: 14.0 g / 10 min (300°C, load 1.2 kg), weight average molecular weight: 170,000 (measured by gel permeation chromatography at 145°C using 1,2,4-trichlorobenzene as a solvent), melting point: 246°C (measured by DSC) SPS2: syndiotactic polystyrene, manufactured by Idemitsu Kosan Co., Ltd., MFR: 9.0 g / 10 min (300°C, load 1.2 kg), weight average molecular weight: 200,000 (measured by gel permeation chromatography at 145°C using 1,2,4-trichlorobenzene as a solvent), melting point: 271°C (measured by DSC) 13 C-NMR measurements confirmed that SPS1 and SPS2 were polystyrene with a syndiotactic structure.

[0054] (Polystyrene (B) exhibiting a specific melt viscoelasticity (tan δ)) B-PS1: Hyperbranched polystyrene, DIC Corporation "HP-780AN", melt viscoelasticity (tan δ) at angular frequency of 1 rad / s: 4.8 (measured at 270°C), MFR: 1.2g / 10min (temperature 200°C, load 5kg)

[0055] (Rubber-like elastomer (C)) SEBS1: Hydrogenated styrene-butadiene-styrene block copolymer, "Tuftec H1041" manufactured by Asahi Kasei Corporation, styrene content 30% by mass, MFR: 5.0g / 10min (temperature 230℃, load 2.16kg) SEBS2: Hydrogenated styrene-butadiene-styrene block copolymer, Kuraray Co., Ltd. "Septon 2104", styrene content 65% by mass, MFR: 0.4g / 10min (temperature 230℃, load 2.16kg)

[0056] (Other resins (D)) HIPS1: High impact polystyrene, PS Japan Co., Ltd. "HT478", MFR: 3.0g / 10min (temperature 200℃, load 5kg) aPS1: polystyrene with atactic structure, "680" manufactured by PS Japan Co., Ltd., MFR: 7.0g / 10min (temperature 200℃, load 5kg) LDPE1: Low-density polyethylene, "LF405H" manufactured by Japan Polyethylene Co., Ltd.

[0057] Example 1 (1) Production and evaluation of resin compositions The components shown in Table 1 were dry-blended in the composition (mass%) shown in Table 1, and then melt-kneaded at 280°C in a single-screw extruder having a diameter of 40 mm to obtain pellets (resin composition). The resulting resin composition was evaluated as follows. The results are shown in Table 1.

[0058] (Melt viscoelasticity (tan δ)) The obtained pellets of the resin composition were placed in the center of a SUS frame of 120 mm square and 1.0 mm thickness, and preheated at 280°C for 5 minutes with a load of 0.1 kN using a vacuum press, then pressed at 280°C for 3 minutes with a load of 20 kN, and cooled to solidify to produce a sheet of 120 mm square and 1.0 mm thickness. The obtained sheet was cut into 30 mm square pieces using a cutter knife to obtain a measurement sample. The melt viscoelasticity (tan δ) was measured using the sample under the following conditions. Measurement equipment: Anton Paar "MCR 302" Fixture: 20mm diameter parallel plate Gap between plates: 0.500mm Shear strain: 8.0% ·Angular frequency: 1rad / s Measurement temperature: (melting point of the resin composition rounded off to the nearest 1st place + 20°C, in Example 1 it is 270°C (melting point of 246°C rounded off to the nearest 1st place 250°C + 20°C) Melting point of resin composition: Using a differential scanning calorimetry (DSC) measuring device (PerkinElmer "DSC 8500"), the temperature was raised from 30°C to 300°C at a rate of 20°C / min, then lowered to 30°C at 20°C / min, and then raised again to 300°C at 20°C / min. The temperature at the maximum point of the endothermic peak was taken as the melting point. When there were two or more endothermic peaks, the melting point was taken as the temperature at the maximum point of the peak on the highest temperature side and with a peak area of ​​0.3 J / g or more.

[0059] (2) Manufacturing of molded products (inflation molding) and evaluation Using the pellets obtained in (1), a 40 mm diameter single-screw (full-flight type screw) extruder was fitted with a circular die with a diameter of 50 mm and a gap of 2 mm, and the resin was melt-extruded vertically (upward) at (the temperature obtained by rounding off the melting point of the resin composition to the nearest 100) ° C. (270 ° C. in Example 1 (250 ° C. + 20 ° C. obtained by rounding off the melting point of 246 ° C.)) at an extrusion rate of 7 kg / hour. Air was fed into the inside of the resin extruded in a circular ring shape so that the blow ratio was 3.3, and the bubble-shaped resin film was taken up at a take-up speed of 10.0 m / min (varied in the range of 10.0 to 35.0 m / min in the bubble stability evaluation), to obtain an inflation film (molded product). An air ring was used during inflation molding, and a heat-insulating material was attached to the stabilizing plate to stabilize the bubbles. Each evaluation was performed on a film taken up at a speed of 10.0 m / min.

[0060] The resulting inflation film (molded product) was evaluated as follows.

[0061] (Maximum take-up speed: bubble stability) In inflation molding, the faster the take-up speed, the faster the deformation speed of the molten resin, which makes the bubble shape more likely to become unstable. If cylindrical bubbles with roughly the same vertical diameter are obtained, the state is stable, but examples of instability include when a constant bubble diameter cannot be maintained and the bubble is partially deflated, when the bubble's expansion starting point fluctuates up and down, or when the bubble becomes twisted or distorted. While maintaining the extrusion rate at 7 kg / h and the blow ratio at 3.3, the film take-up speed was gradually increased from 10.0 m / min (maximum 35.0 m / min), and the maximum take-up speed at which the bubble could be kept stable was recorded and used as bubble stability. In other words, the higher the maximum take-up speed, the higher the bubble stability.

[0062] (Tensile strength (Mpa)) The test was conducted according to a method compliant with JIS K7127. Specifically, the film was cut into a strip shape of 150 mm in length and 10 mm in width so that the long side was in the direction of resin flow to prepare a test piece, and the test was conducted with a chuck distance of 100 mm and a tensile speed of 50 mm / min. The stress at which the film broke from the obtained stress-strain curve was taken as the tensile strength.

[0063] (Tensile elongation at break (%)) The test was conducted according to a method compliant with JIS 7127. Specifically, the film was cut into a strip shape of 150 mm in length and 10 mm in width so that the long side was in the direction of resin flow to prepare a test piece, and the test was conducted with a chuck distance of 100 mm and a tensile speed of 50 mm / min. The strain at which the film broke from the obtained stress-strain curve was taken as the tensile elongation.

[0064] (Haze(%)) Using a measuring device ("HAZE METER NDH5000" manufactured by Nippon Denshoku Industries Co., Ltd.), the haze was measured at a location where the film was 25 μm thick in accordance with JIS K7136.

[0065] Examples 2 to 5, Comparative Examples 1 to 6 Pellets (resin compositions) were produced and evaluated in the same manner as in Example 1, except that the composition was changed as shown in Table 1. The results are shown in Table 1. Furthermore, using the obtained pellets, molded articles were produced and evaluated in the same manner as in Example 1 (inflation molding (referred to as "inf." in the tables)) in Examples 2 to 4 and Comparative Examples 1 to 5. In Example 5 and Comparative Example 6, films (molded articles) were produced not by inflation molding but by the extrusion lamination evaluation method described below (referred to as "E / L" in the tables)) and evaluated in the same manner as in Example 1. The results are shown in Table 1. In the table, "-" indicates that the evaluation was not performed. In Example 5, the haze was measured in the same manner as in Example 1 using a film obtained by the extrusion lamination evaluation method described below. In addition, for the tensile breaking strength of Comparative Example 5 (36), the strength was higher at the yield point, so the strength at the yield point was recorded.

[0066] (Extrusion Lamination Evaluation Method: Neck-in Size and Variation) A T-die with a lip width of 500 mm was attached to a single-screw extruder with a gear pump, and a resin mixture obtained by dry-blending the components shown in Table 1 in the composition (mass%) shown in Table 1 was charged into a hopper, melt-extruded at 280°C at a discharge rate of 5.2 kg / hour, cast onto a casting roll at a temperature of 95°C, and a film was produced at a take-up speed of 6.5 m / min. The film width was measured for a length of 1.5 m of the obtained film, and the difference between the lip width and the film width was taken as the size of the neck-in. The difference between the maximum and minimum values ​​of the film width was taken as the variation in the neck-in.

[0067] [Table 1]

Claims

1. The polymer comprises polystyrene (A) having a syndiotactic structure as a main component, The melt viscoelasticity (tan δ) at an angular frequency of 1 rad / s is 7.7 or less, More than 80% by mass is a styrene-based resin; Resin composition.

2. The resin composition according to claim 1, comprising polystyrene (B) having a melt viscoelasticity (tan δ) of 7.7 or less at an angular frequency of 1 rad / s.

3. The resin composition according to claim 2 , wherein the polystyrene (B) is a hyperbranched polystyrene.

4. The resin composition according to any one of claims 1 to 3, comprising a rubber-like elastomer (C).

5. The resin composition according to any one of claims 1 to 4, wherein the polyethylene content is less than 20 mass%.

6. The resin composition according to any one of claims 1 to 5, which is for extrusion molding.

7. The resin composition according to any one of claims 1 to 6, which is for use in inflation molding or extrusion lamination.

8. An extrusion molded product obtained from the resin composition according to any one of claims 1 to 7.

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