Polypropylene resin composition and inorganic substance powder-containing fiber

Abstract

To provide a polypropylene resin composition which is easily produced because of excellent spinnability and has uniform and sufficient quality including mechanical properties while being highly filled with an inorganic substance powder.SOLUTION: Provided is a polypropylene composition contains a thermoplastic resin and an inorganic substance powder in a mass ratio of 70:30-99.9:0.1. Also provided is an inorganic substance powder-containing fiber including the same.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a polypropylene resin composition and a fiber containing an inorganic substance powder.

Background Art

[0002] Conventionally, fibers produced by melt spinning have been widely used as medical materials, sanitary materials, filters, building materials, civil engineering materials, coating materials, separators, absorbent articles, packaging materials, supporting materials, backing materials, and living materials such as clothing.

[0003] However, from the perspective of environmental protection, reducing the consumption of thermoplastic resins used in melt-spun fibers has become an issue in recent years. From this point of view, an inorganic substance powder highly filled thermoplastic resin composition obtained by highly filling an inorganic substance powder in a thermoplastic resin has been proposed, and its practical application to sheets and the like has been proposed (see, for example, Patent Document 1).

[0004] When an inorganic substance powder is highly compounded in a thermoplastic resin, various physical properties corresponding to the properties of the compounded inorganic substance powder, such as the coloring property, high whiteness, hydrophilicity or hydrophobicity, separation function, and catalytic function of the fiber, can be imparted to the fiber. For example, while increasing the rigidity of the fiber, a soft touch can be imparted. Therefore, a spunbond nonwoven fabric obtained by melt spinning a thermoplastic resin highly filled with an inorganic substance powder has been proposed (see, for example, Patent Document 2). However, when trying to make such a thermoplastic resin highly filled with an inorganic substance powder into a melt-spun fiber, there is a concern that yarn breakage may occur at the interface between the inorganic substance and the thermoplastic resin in the spinning process, and there are drawbacks that the spinning speed cannot be increased or stable production cannot be achieved in the manufacturing process.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0006] For example, Patent Document 2 mentions a spunbond nonwoven fabric composed of fibers containing 50% by mass or more of an inorganic substance powder, but does not describe the relationship between the forming speed of the melt-spun fiber and thread breakage or yarn breakage. It is presumed that even if an attempt is made to obtain a melt-spun fiber from the description of Patent Document 2, the spinnability will not be practically acceptable. There is a demand for inorganic substance powder-containing fibers that can reduce the consumption of thermoplastic resin from the inorganic substance powder content, have moldability, and be practically acceptable, and contribute to the solution of environmental problems.

[0007] In view of the above problems, an object of the present invention is to provide a polypropylene resin composition having excellent spinnability while being filled with an inorganic substance powder.

MEANS FOR SOLVING THE PROBLEMS

[0008] As a result of intensive studies to solve the above problems, the present inventor has found that by blending a specific inorganic substance powder with a polypropylene resin, polypropylene fibers that can also contribute to the solution of environmental problems can be stably obtained on an industrial scale, and the present invention has been completed. Specifically, the present invention provides the following.

[0009] (1) A polypropylene resin composition containing a polypropylene resin and an inorganic substance powder in a mass ratio of 70:30 to 99.9:0.1. (2) The polypropylene resin composition according to (1), wherein the inorganic substance powder is silica having an average particle diameter measured by a laser diffraction method of 1 μm or more and 10 μm or less. (3) The silica has a BET specific surface area of 30 m 2 / g or more and 700 m 2The polypropylene resin composition according to (2), having a bulk density of 0.02 g / ml or more and 0.5 g / ml or less, a pore volume of 0.3 ml / g or more and 3 ml / g or less, and an oil absorption amount of 50 ml / 100 g or more and 500 ml / 100 g or less. (4) The polypropylene resin composition according to any one of (1) to (3), wherein the polypropylene resin is at least one resin selected from a propylene homopolymer, a propylene-ethylene copolymer, and a propylene-butene-ethylene copolymer. (5) The polypropylene resin composition according to any one of (1) to (4), wherein the polypropylene resin has a melt flow rate (MFR) of 1 g / 10 min or more and 40 g / 10 min or less. (6) An inorganic substance powder masterbatch containing the polypropylene resin composition according to any one of (1) to (5). (7) A polypropylene resin composition containing a polypropylene-based resin and the inorganic substance powder masterbatch according to (6). (8) An inorganic substance powder-containing fiber containing the polypropylene resin composition according to any one of (1) to (5) or the polypropylene resin composition according to (7). (9) A rope, fabric, carpet, artificial turf, or concrete reinforcing fiber using the inorganic substance powder-containing fiber according to (8).

Advantages of the Invention

[0010] According to the present invention, there is provided a polypropylene resin composition which has excellent spinnability even when filled with an inorganic substance powder, is easy to manufacture, and has uniform and sufficient quality including mechanical properties. The polypropylene resin composition containing a polypropylene resin and an inorganic substance powder in a mass ratio of 70:30 to 99.9:0.1 is excellent in spinnability, so that fibers containing the inorganic substance powder can be easily manufactured. Further, the inorganic substance powder is uniformly dispersed, and fibers do not break starting from an agglomerated portion such as the inorganic substance powder even during high-speed molding. The polypropylene resin composition of the present invention also contains a large amount of the inorganic substance powder, so that the consumption amount of the thermoplastic resin can be reduced, which can also contribute to the solution of environmental problems. Further, the fibers containing the inorganic substance powder including the obtained polypropylene-based resin composition have high strength, and are extremely suitable for uses such as ropes, fabrics, carpets, artificial turf, and fibers for concrete reinforcement.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, specific embodiments of the present invention will be described in detail, but the present invention is not particularly limited thereto.

[0012] The polypropylene resin composition according to the present invention is composed of a polypropylene resin and an inorganic substance powder. And the mass ratio of the polypropylene resin and the inorganic substance powder is contained in a ratio of 70:30 to 99.9:0.1.

[0013] The polypropylene resin composition may contain components other than the above-described components. However, when the entire polypropylene resin composition is 100% by mass, preferably 90% by mass or more, more preferably 95% by mass or more, is composed of the polypropylene resin and the inorganic substance powder.

[0014] ≪Polypropylene Resin Composition≫ [Polypropylene Resin] The polypropylene resin, which is the main component of the polypropylene resin composition of the present invention, is not particularly limited in its type, and any of a propylene homopolymer, a propylene block copolymer, a propylene random copolymer, etc. can be used. Examples of the propylene random copolymer include crystalline polypropylene resins obtained by copolymerizing propylene and an α-olefin. Examples of the α-olefin include one or more α-olefins selected from ethylene, butene-1, hexene-1, octene-1, decene-1, 3-methylbutene-1, 4-methylpentene-1, 2-methylpentene-1, etc. Examples of the propylene block copolymer include, for example, a polypropylene resin composed of a crystalline polypropylene component obtained by polymerizing propylene or copolymerizing propylene and a small amount of α-olefin, and a low-crystalline or amorphous propylene-α-olefin random copolymer component obtained by copolymerizing propylene and an α-olefin. Examples of the α-olefin include one or more α-olefins selected from ethylene, butene-1, hexene-1, octene-1, decene-1, 3-methylbutene-1, 4-methylpentene-1, 2-methylpentene-1, etc. In the low-crystalline or amorphous propylene-α-olefin random copolymer component, ethylene is preferably used as the α-olefin, and one or more α-olefins selected from butene-1, hexene-1, octene-1, decene-1, 3-methylbutene-1, 4-methylpentene-1, 2-methylpentene-1, etc. may be copolymerized. The polypropylene resin is preferably at least one resin selected from a propylene homopolymer, a propylene-ethylene copolymer, and a propylene-butene-ethylene copolymer.

[0015] Among these, in order to obtain higher-strength polypropylene fibers, it is desirable that the polypropylene resin be a propylene homopolymer. Among these, in order to obtain more flexible polypropylene fibers, it is desirable that the polypropylene resin be a propylene random copolymer, for example, a propylene-ethylene copolymer or a propylene-butene-ethylene copolymer.

[0016] The method for producing the polypropylene resin is not particularly limited, and it may be obtained by any method such as a method using a Ziegler-Natta catalyst, a metallocene catalyst, or a method of treating the obtained polypropylene resin with a radical initiator such as oxygen or peroxide.

[0017] The polypropylene resin used herein is not particularly limited, and various ordinary ones can be used. Preferably, the melt flow rate (MFR) is 1 g / 10 min or more and 40 g / 10 min or less, more preferably 3 g / 10 min or more and 35 g / 10 min or less, and even more preferably 5 g / 10 min or more and 25 g / 10 min or less. When the MFR is within this range, the spinnability of the polypropylene resin composition is enhanced, and fibers with better quality stability and uniformity can be obtained. In this specification, the MFR shall be measured at 230°C under a load of 2.16 kg in accordance with JIS K-7210-1995. Also, the polypropylene resin may have any stereoregularity, but preferably, the main component is a polypropylene resin having an isotactic structure. By using a polypropylene resin having such a three-dimensional structure, the spinnability and the physical properties of the obtained nonwoven fabric can be further improved. From the same viewpoint, the density is 0.86 g / cm 3 or more and 0.95 g / cm 3 or less, particularly preferably 0.88 to 0.93 g / cm 3 of the polypropylene resin is preferably used.

[0018] [Inorganic substance powder] The inorganic substance powder is not particularly limited. For example, it includes powdered carbonates, sulfates, silicates, phosphates, borates, oxides, or hydrates thereof, such as calcium, magnesium, aluminum, titanium, iron, zinc, etc. Specifically, for example, calcium carbonate, magnesium carbonate, zinc oxide, titanium oxide, silica (silicon dioxide), alumina, clay, talc, kaolin, aluminum hydroxide, magnesium hydroxide, aluminum silicate, magnesium silicate, calcium silicate, aluminum sulfate, magnesium sulfate, calcium sulfate, magnesium phosphate, barium sulfate, silica sand, carbon black, zeolite, molybdenum, diatomaceous earth, sericite, shirasu, calcium sulfite, sodium sulfate, potassium titanate, bentonite, wollastonite, dolomite, graphite, etc. These may be synthetic or derived from natural minerals, and they may be used alone or in combination of two or more kinds.

[0019] Furthermore, the shape of the inorganic substance powder is not particularly limited, and it may be any of particulate, flaky, granular, fibrous, etc. Also, as for the particulate form, it may be spherical as generally obtained by a synthetic method, or may be irregularly shaped as obtained by pulverizing collected natural minerals.

[0020] As these inorganic substance powders, preferably, calcium carbonate, magnesium carbonate, zinc oxide, titanium oxide, silica, alumina, clay, talc, kaolin, aluminum hydroxide, magnesium hydroxide, barium sulfate, etc. are used, and silica is particularly preferred. Furthermore, as for silica, it may be prepared by a synthetic method and may have an amorphous or spherical shape, and it is also possible to combine these.

[0021] Here, the silica suitably used in the present invention has an average particle diameter measured by the laser diffraction method of 1 to 10 μm and a BET specific surface area of 30 to 700 m 2 / g, amorphous silica with a bulk density of 0.02 g / ml or more and less than 0.5 g / ml, a pore volume of 0.3 to 3 ml / g, and an oil absorption of 50 to 500 ml / 100 g. Such silica has a lower bulk density, so the weight reduction improvement effect is more significant compared to other inorganic substance powders. In this specification, the average particle diameter measured by the laser diffraction method can be measured using a laser diffraction particle size distribution measuring device. The BET specific surface area can be calculated from nitrogen adsorption measurement using an automatic gas adsorption measuring device. The bulk density can be calculated by putting 5 g of silica into a graduated cylinder, shaking it, and then measuring the occupied volume after standing. The pore volume can be calculated from nitrogen adsorption measurement using an automatic gas adsorption measuring device. Also, the oil absorption can be determined in accordance with JIS K5101.

[0022] Also, as long as the silica satisfies the above characteristics, in particular, it may or may not be surface-treated with a surface treatment agent. For example, by being treated with a surface treatment agent, the effect of improving the dispersibility of silica can be obtained. Examples of the surface treatment agent include paraffin, fatty acid, polyhydric alcohol, silane coupling agent, silicone oil, modified silicone oil, citric acid, etc.

[0023] Furthermore, as the silica, a product that satisfies the above characteristics can be selected from commercially available silica and used. The silica that satisfies the above characteristics can be obtained, for example, from Fuji Silysia Chemical Ltd., Grace Japan Co., Ltd., etc.

[0024] As the inorganic substance powder such as silica, the average particle diameter measured by the laser diffraction method is preferably 1 to 10 μm, more preferably 1.5 to 7 μm, and even more preferably 1.8 to 5 μm. When the average particle diameter is in the above range, it is possible to suppress the occurrence of thread breakage starting from the aggregation of the inorganic substance powder and the occurrence of thread breakage starting from the non-uniformity of the fibers due to the thickening of the resin composition, and the spinnability is good.

[0025] In addition, the BET specific surface area of silica (specific surface area measured by the BET method) is preferably 30 to 700 m 2 / g, more preferably 100 to 700 m 2 / g, and even more preferably 250 to 700 m 2 / g. The BET specific surface area is correlated with the oil absorption amount and can be said to indicate the structure of silica. When the BET specific surface area is within the above range, the dispersibility is excellent and secondary aggregation is suppressed. When the BET specific surface area is 700 m 2 / g or less, the silica has a hard and difficult-to-collapse structure, making it difficult to undergo secondary aggregation. As a result, the aggregates in the fiber decrease, yarn breakage is suppressed, and the moldability is improved. Also, when the specific surface area is 30 m 2 / g or more, the particles are soft, damage due to rubbing between fibers is suppressed, the appearance is improved, and the spinning property does not decrease much.

[0026] Furthermore, the bulk density of silica is preferably 0.02 g / ml or more and less than 0.5 g / ml, more preferably 0.05 to 0.4 g / ml. When the bulk density is within the above range, the dispersibility is excellent and secondary aggregation is suppressed. When the bulk density is less than 0.5 g / ml, the particles are soft, damage due to rubbing between fibers is suppressed, and the appearance is improved. Also, when the bulk density is 0.02 g / ml or more, the silica has a hard and difficult-to-collapse structure, making it difficult to undergo secondary aggregation. As a result, the aggregates in the fiber decrease, yarn breakage is suppressed, and the moldability is improved.

[0027] The pore volume of silica measured by the N 2 adsorption method is preferably 0.3 to 3 ml / g, more preferably 0.4 to 2 ml / g. When the pore volume is within the above range, the dispersibility is excellent and secondary aggregation is suppressed. When the pore volume is 3 ml / g or less, the silica becomes hard and difficult to collapse, so when mixing with the polypropylene resin, it is difficult to aggregate, yarn breakage is suppressed, and the moldability is improved.

[0028] In addition, the silica used in the present invention has an oil absorption of 50 to 500 ml / 100 g as measured in accordance with JIS K5101. When the oil absorption is within the above range, the dispersibility is excellent and secondary aggregation is suppressed.

[0029] [Ratio of polypropylene resin to inorganic substance powder] The mass ratio of the polypropylene resin contained in the polypropylene resin composition to the inorganic substance powder is in the range of 70:30 to 99.9:0.1, preferably in the range of 80:20 to 99:1, more preferably in the range of 85:15 to 98:2, and even more preferably in the range of 90:10 to 95:5. When the total of the polypropylene resin and the inorganic substance powder is 100% by mass, if the proportion of the inorganic substance powder is less than 0.1% by mass, the physical properties aimed at by the inorganic substance powder may not be exhibited, and it may not contribute much to the environmental aspect. On the other hand, if the proportion of the inorganic substance powder is higher than 30% by mass, when producing inorganic substance powder-containing fibers using the polypropylene resin composition, yarn breakage may occur and the spinnability may be poor.

[0030] [Other additives] In the polypropylene resin composition, in addition to the silica described above, other additional components can be blended within a range that does not significantly impair the effects of the present invention. Such optional components include antioxidants, crystal nucleating agents, clarifying agents, slip agents, antiblocking agents, antistatic agents, antifogging agents, neutralizing agents, metal deactivators, colorants, dispersants, peroxides, flame retardants, fillers, and fluorescent brighteners used in ordinary polyolefin resin materials. These other additives may be used alone or in combination of two or more. These additives may be blended in the kneading step, or may be previously blended with other components such as resins before the kneading step.

[0031] The addition amount of the additive is not particularly limited. For example, when the entire polypropylene resin composition is 100% by mass, the content of each additive is added in a proportion of about 0 to 5.0% by mass, preferably about 0.1 to 3.0% by mass, particularly about 0.5 to 2.0% by mass, and it is desired to add in a proportion such that the total amount of the additives is 10.0% by mass or less.

[0032] Examples of those considered important among these will be given and explained below, but it is not limited to those exemplified below.

[0033] As the colorant, any of ordinary organic pigments, inorganic pigments, or dyes can be used. Specifically, organic pigments such as azo-based, anthraquinone-based, phthalocyanine-based, quinacridone-based, isoindolinone-based, dioxazine-based, perinone-based, quinophthalone-based, perylene-based pigments, and inorganic pigments such as ultramarine, titanium oxide, titanium yellow, iron oxide (red lead), chromium oxide, zinc white, carbon black, etc. can be mentioned.

[0034] As the antioxidant, phenolic antioxidants, phosphorus-based antioxidants, sulfur-based antioxidants, etc. can be used. Specific examples of phenolic antioxidants include tris-(3,5-di-t-butyl-4-hydroxybenzyl)-isocyanurate, n-octadecyl 3-(4'-hydroxy-3',5-di-tert-butylphenyl)propionate, pentaerythrityl-tetrakis{3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate}, 4,4',4''-[(2,4,6-trimethyl-1,3,5-benzenetriyl)tris(methylene)]tris[2,6-bis(1,1-dimethylethyl)phenol, 3,9-bis[2-{3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy}-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5,5]undecane, 1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)isocyanuric acid, etc. Specific examples of phosphorus-based antioxidants include tris (mixed, mono and dinonylphenyl phosphite), tris (2,4-di-t-butylphenyl) phosphite, 4,4'-butylidenebis (3-methyl-6-t-butylphenyl-di-tridecyl) phosphite, 1,1,3-tris (2-methyl-4-di-tridecyl phosphite-5-t-butylphenyl) butane, bis (2,4-di-t-butylphenyl) pentaerythritol-di-phosphite, tetrakis (2,4-di-t-butylphenyl)-4,4'-biphenylenediphosphonite, tetrakis (2,4-di-t-butyl-5-methylphenyl)-4,4'-biphenylenediphosphonite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol-di-phosphite, and the like. Specific examples of sulfur-based antioxidants include di-stearyl-thio-di-propionate, di-myristyl-thio-di-propionate, pentaerythritol-tetrakis-(3-lauryl-thio-propionate), and the like. These antioxidants can be used singly or in combination of two or more, as long as the effects of the present purpose are not impaired.

[0035] Specific examples of neutralizing agents include calcium stearate, zinc stearate, hydrotalcite, Mizukalac (manufactured by Mizusawa Chemical Industry Co., Ltd.), and the like.

[0036] Examples of the slipping agent include monoamides, substituted amides, bisamides, etc., and they can be used alone or in combination of two or more. Specific examples of monoamides include, as saturated fatty acid monoamides, lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide, etc. Specific examples of unsaturated fatty acid monoamides include oleic acid amide, erucic acid amide, ricinoleic acid amide, etc. Specific examples of substituted amides include N-stearyl stearic acid amide, N-oleyl oleic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide, N-oleyl palmitic acid amide, etc. Specific examples of bisamides include, as saturated fatty acid bisamides, methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bistearic acid amide, ethylene bisisostearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene bishydroxystearic acid amide, N,N'-distearyl adipic acid amide, N,N'-distearyl sebacic acid amide, etc. Specific examples of unsaturated fatty acid bisamides include ethylene bisoleic acid amide, hexamethylene bisoleic acid amide, N,N'-dioleyl adipic acid amide, N,N'-dioleyl sebacic acid amide, etc. Specific examples of aromatic bisamides include m-xylylene bisstearic acid amide, N,N'-distearyl isophthalic acid amide, etc. Among these, in particular, among fatty acid amides, oleic acid amide, erucic acid amide, and behenic acid amide are preferably used.

[0037] The flame retardant is not particularly limited. For example, halogen-based flame retardants, or non-phosphorus halogen-based flame retardants such as phosphorus-based flame retardants and metal hydrates can be used. Specific examples of halogen-based flame retardants include halogenated bisphenol compounds such as halogenated bisphenylalkane, halogenated bisphenyl ether, halogenated bisphenyl thioether, and halogenated bisphenyl sulfone; bisphenol-bis(alkyl ether) compounds such as brominated bisphenol A, brominated bisphenol S, chlorinated bisphenol A, and chlorinated bisphenol S. Specific examples of phosphorus-based flame retardants include aluminum tris(diethylphosphinate), bisphenol A bis(diphenyl phosphate), triaryl isopropyl phosphate, cresyl di-2,6-xylyl phosphate, and aromatic condensed phosphate esters. Examples of metal hydrates include aluminum trihydrate, magnesium dihydroxide, or combinations thereof. These can be used alone or in combination of two or more. Furthermore, for example, antimony oxides such as antimony trioxide and antimony pentoxide, zinc oxide, iron oxide, aluminum oxide, molybdenum oxide, titanium oxide, calcium oxide, magnesium oxide, etc. can also be used in combination as flame retardant aids.

[0038] <<Manufacture of Polypropylene Resin Composition>> The polypropylene resin composition of the present invention can be produced using an ordinary single-screw extruder, twin-screw extruder, etc. For example, a container for charging a main component such as a polypropylene resin to be supplied to the extruder (also referred to as a "main hopper"), and a supply port (also referred to as a "side feed supply port") through which an additional component such as silica can be supplied separately from the polypropylene resin can be used. In this case, the polypropylene resin composition can be produced by supplying the polypropylene resin from the main hopper to the extruder and supplying silica to the extruder from the side feed supply port. In such an extruder, it is preferable to have a main hopper upstream and a side feed supply port downstream. More specifically, a predetermined amount of polypropylene resin and other additives are put into a Henschel mixer (trade name), super mixer, ribbon blender, etc. as necessary and mixed (dry blended), and then charged into the extruder by the main hopper. After melting this blend, a predetermined amount of silica is charged through the side feed supply port and further kneaded in a temperature range of about 100 to 280 °C to obtain a polypropylene resin composition.

[0039] When kneading and melting the above raw materials before spinning and forming, the polypropylene resin composition may be once formed into the form of pellets. In that case, the shape of the pellets is not particularly limited, and for example, the pellets can be cylindrical, spherical, ellipsoidal, etc. The size of the pellets can be appropriately set according to the shape and the type of the spinning and forming machine. For example, in the case of spherical pellets, the diameter can be 1 to 10 mm. In the case of ellipsoidal pellets, they can be ellipsoidal with an aspect ratio of 0.1 to 1.0 and 1 to 10 mm in length and width. In the case of cylindrical pellets, they can be within the range of 1 to 10 mm in diameter and within the range of 1 to 10 mm in length.

[0040] <<Fibers of the polypropylene resin composition>> By spinning the above polypropylene resin composition, fibers containing an inorganic substance powder can be obtained.

[0041] <<Method for producing fibers of the polypropylene resin composition>> The production of fibers of the polypropylene resin composition is preferably carried out by multifilament forming, monofilament forming, flat yarn forming, etc. The above resin composition is melt-spun using a nozzle to obtain fibers for stretching (including filaments, yarns, etc.). The spinning temperature is preferably set at a temperature 30 to 80 °C higher than the melting point of the resin composition. The fibers for stretching are preferably stretched after applying draft. The draw ratio is usually 5 to 10 times, preferably 6 to 8 times. Various methods can be adopted for stretching, such as performing heat stretching after cold stretching, or only performing heat stretching without performing cold stretching. The cold stretching is preferably usually at 40 °C or lower, and the heat stretching is preferably usually carried out at 120 to 160 °C.

[0042] The inorganic substance powder-containing fiber containing the polypropylene resin composition of the present invention has excellent strength, and it is extremely effective to use this as a rope, a fabric (fabric), a carpet, artificial turf, a concrete reinforcing fiber, etc. The carpet can be obtained by weaving, sewing or adhering the inorganic substance powder-containing fiber to the base fabric for the carpet. The artificial turf can be obtained by sewing or adhering the inorganic substance powder-containing fiber to the base fabric for the artificial turf. Further, as the concrete reinforcing fiber, the inorganic substance powder-containing fiber can be used as a single fiber or made into a multifilament.

[0043] <<Other uses of the polypropylene resin composition>> The polypropylene resin composition of the present invention can also be used as an inorganic particulate masterbatch for polypropylene films, and is used for forming polypropylene films excellent in antiblocking property, dispersibility, fish-eye characteristics, scratch resistance, printing characteristics, and transparency, and can be used as a polypropylene resin composition suitable as an antiblocking agent masterbatch. In that case, it is applicable to applications where an antiblocking agent is required, and the polypropylene resin composition of the present invention can be added to any propylene-based resin or propylene-based resin composition at an arbitrary ratio and then formed by an ordinary film forming machine. Specific examples of the preferable molded article thus obtained include polypropylene films such as biaxially stretched polypropylene films and unstretched polypropylene films.

Examples

[0044] Hereinafter, the present invention will be described more specifically based on examples. These examples are described only for the purpose of exemplifying specific aspects and embodiments in order to make it easier to understand the concept and technical idea of the present invention disclosed in this specification and described in the appended claims, and the present invention is not limited to these examples at all.

[0045] [Measurement and Evaluation Methods] (1) MFR (Melt Flow Rate) Measured in accordance with JIS K-7210-1995 at 230 °C under a load of 2.16 kg.

[0046] (2) Melting Peak Temperature (Tm) Using a differential scanning calorimeter (DSC manufactured by Seiko Instruments Inc.), a sample amount of 5.0 mg was taken, held at 200 °C for 5 minutes, then crystallized at a temperature-lowering speed of 10 °C / min to 40 °C, and the melting peak temperature (Tm) when melted at a temperature-rising speed of 10 °C / min was measured.

[0047] (3) Ethylene Content, Butene Content The ethylene content (unit: mass %) and butene content (unit: mass %) in the propylene-ethylene-butene polymer were measured by the IR method on a polymer pressed and formed into a sheet. Specifically, the contained propylene component content and α-olefin component content were measured using the IR method described in the "New Edition Polymer Analysis Handbook" (edited by the Chemical Society of Japan and the Polymer Analysis Research Discussion Group, Kiyokawa Shoten (1995)). For example, it was calculated from the peak height of the methylene chain observed near 730 cm -1 and so on.

[0048] [Silica properties] (1) Average particle size: Measured using a laser diffraction particle size distribution measuring device. (2) BET specific surface area: Calculated from nitrogen adsorption measurement using an automatic gas adsorption amount measuring device. (3) Bulk density: Calculated by putting 5 g of silica into a graduated cylinder, shaking it, and then allowing it to stand still and measuring the occupied volume. (4) Pore volume: Calculated from nitrogen adsorption measurement using an automatic gas adsorption amount measuring device. (5) Oil absorption amount: Measured according to JIS K5101.

[0049] [Fiber properties] (1) Spinnability: The presence or absence of thread breakage during thread formation was visually evaluated according to the following criteria. 〇: No thread breakage occurred for 1 hour or more. △: Thread breakage occurred for more than 0.5 hour and less than 1 hour. ×: Thread breakage occurred for less than 0.5 hour.

[0050] [Materials used] (1) Polypropylene resin (A) As the polypropylene resin, the following was used. A-1: Propylene-ethylene-butene copolymer powder (MFR = 8.0 g / 10 min, Tm = 139 °C, ethylene content = 2.8 mass %, butene content = 2.8 mass %, manufactured by Nippon Polypro Co., Ltd.)

[0051] (2) Inorganic substance powder (B) As the inorganic substance powder (B), the following were used. B-1: Silica, "Silicia 550" manufactured by Fuji Silysia Chemical Ltd. (average particle diameter 3.7 μm, BET specific surface area 500 m 2 / g, bulk density 0.31 g / ml, pore volume 0.8 ml / g, oil absorption 140 ml / 100 g) B-2: Silica, "Silicia 530" manufactured by Fuji Silysia Chemical Ltd. (average particle diameter 2.7 μm, BET specific surface area 500 m 2 / g, bulk density 0.14 g / ml, pore volume 0.8 ml / g, oil absorption 170 ml / 100 g) B-3: Silica, "Siloblock 35" manufactured by Grace Japan Co., Ltd. (average particle diameter 4.0 μm, BET specific surface area 500 m 2 / g, bulk density 0.23 g / ml, pore volume 1.0 ml / g, oil absorption 200 ml / 100 g)

[0052] (3) Antioxidant (C) As the antioxidant (C), the following were used. C-1: IR1010 (trade name, manufactured by BASF Japan Ltd.): Pentaerythrityl-tetrakis{3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate} C-2: IR1330 (trade name, manufactured by BASF Japan Ltd.): 4,4’,4’’-[(2,4,6-trimethyl-1,3,5-benzenetriyl)tris(methylene)]tris[2,6-bis(1,1-dimethylethyl)phenol C-3: IR1076 (trade name, manufactured by BASF Japan Ltd.): n-Octadecyl 3-(4’-hydroxy-3’,5-di-tert-butylphenyl)propionate C-4: IF168 (trade name, manufactured by BASF Japan Ltd.): Tris(2,4-di-t-butylphenyl)phosphite

[0053] (4) Neutralizing agent (D) As the neutralizing agent (D), the following were used. D-1: DHT4A (manufactured by Kyowa Chemical Industry Co., Ltd., trade name): magnesium aluminum hydroxide carbonate hydrate D-2: CAST (manufactured by Sakai Chemical Industry Co., Ltd., trade name): calcium stearate

[0054] [Material composition] [Examples 1 - 14, Comparative Examples 1 - 2] Polypropylene resin (A), silica (B), antioxidant (C), and neutralizing agent (D) were used in the blending ratios shown in Tables 1 and 2. The blending amounts of the antioxidant (C) and the neutralizing agent (D) are shown as "parts by mass (external)" when the total of the polypropylene resin (A) and silica (B) is 100 parts by mass.

[0055] Using a 30 mmφ twin - screw extruder, the above - mentioned raw materials were fed from the main hopper with polypropylene resin (A), antioxidant (C), and neutralizing agent (D), melted at 190°C, and then silica (B) was fed from the side - feed port and kneaded to obtain pellets of the polypropylene resin compositions of Examples 1 - 14 and Comparative Examples 1 - 2.

[0056] The pellets of each of Examples 1 - 14 and Comparative Examples 1 - 2 prepared were melt - spun using a multi - filament spinneret with a gear pump (die: 0.8 mmφ×30 holes) at a spinning temperature of 240°C and a winding speed of 200 m / min to obtain undrawn yarns of about 15 dtex. Subsequently, drawing was carried out under the conditions of a feed roll temperature of 90°C, a heater temperature at the draw point of 130°C, and a draw roll temperature of 110°C to obtain double - drawn yarns. The evaluation results are shown in Tables 1 and 2.

[0057]

Table 1

[0058]

Table 2

[0059] As is clear from Tables 1 and 2, the polypropylene resin composition of the present invention has good spinnability, no yarn breakage or thread breakage occurs during molding, and good fibers are obtained. On the other hand, in the fibers of Comparative Examples 1 and 2, spinning could not be performed smoothly and yarn breakage occurred frequently.

Claims

1. A polypropylene resin composition containing polypropylene resin and inorganic substance powder in a mass ratio of 70:30 to 99.9:0.

1.

2. The polypropylene resin composition according to Claim 1, wherein the inorganic substance powder is silica having an average particle diameter of 1 μm or more and 10 μm or less measured by a laser diffraction method.

3. The silica has a BET specific surface area of 30 m ２ / g or more and 700 m ２ / g or less, a bulk density of 0.02 g / ml or more and 0.5 g / ml or less, a pore volume of 0.3 ml / g or more and 3 ml / g or less, and an oil absorption amount of 50 ml / 100 g or more and 500 ml / 100 g or less. The polypropylene resin composition according to claim 2.

4. The polypropylene resin composition according to any one of Claims 1 to 3, wherein the polypropylene resin is at least one resin selected from a propylene homopolymer, a propylene-ethylene copolymer, and a propylene-butene-ethylene copolymer.

5. The polypropylene resin composition according to any one of Claims 1 to 3, wherein the polypropylene resin has a melt flow rate (MFR) of 1 g / 10 min or more and 40 g / 10 min or less.

6. An inorganic substance powder masterbatch containing the polypropylene resin composition according to any one of Claims 1 to 3.

7. A polypropylene resin composition containing a polypropylene-based resin and the inorganic substance powder masterbatch according to Claim 6.

8. An inorganic substance powder-containing fiber containing the polypropylene resin composition according to any one of Claims 1 to 3 or the polypropylene resin composition according to Claim 7.

9. A rope, fabric, carpet, artificial turf, or fiber for concrete reinforcement using the inorganic substance powder-containing fiber according to Claim 8.

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