Inorganic powder-filled resin composition, molding for welding, and resin molding

Abstract

To provide an inorganic powder-filled resin composition capable of welding a molding.SOLUTION: An inorganic powder-filled resin composition contains thermoplastic resin including propylene α-olefin-based random copolymer, inorganic powder, fatty acid zinc having the carbon number of 15 or more and 20 or less, fatty acid having the carbon number of 15 or more and 20 or less, and paraffin oil. The content mass ratio of the thermoplastic resin and the inorganic powder is 50:50 to 10:90, the content of the fatty acid zinc is 0.1 mass% or more and 0.9 mass% or less, and the content of the fatty acid is 0.2 mass% or more and 1.8 mass% or less. The mass ratio of the content of the fatty acid zinc and the content of the fatty acid is 10:30 to 10:15, and the amount of the paraffin oil is 0.5 mass% or more and 3.5 mass% or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an inorganic powder-filled resin composition, a molded article for welding, and a resin molded article.

Background Art

[0002] Conventionally, various products using an inorganic powder-filled resin composition in which calcium carbonate powder is highly filled in a thermoplastic resin have been known (for example, Patent Document 1). Such an inorganic powder-filled resin composition has advantages of a small amount of thermal shrinkage and excellent impact resistance.

[0003] In recent years, it has been desired to apply the inorganic powder-filled resin composition to a wider range of uses, and it has been studied to replace molded articles obtained from the inorganic powder resin composition with conventional resin molded articles. Therefore, it has been required to integrate a molded article obtained from the inorganic powder-filled resin composition with other parts, or to join the molded article and other parts by welding.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the inorganic powder-filled resin composition as described in Patent Document 1 above, the amount of inorganic powder relative to the amount of thermoplastic resin is very large. Therefore, it is difficult to join a molded article obtained from the inorganic powder-filled resin composition to other parts by welding, and even if it can be joined, it is difficult to sufficiently increase its strength.

[0006] The present invention has been made in view of the above problems of the prior art. Specifically, an object of the present invention is to provide an inorganic powder-filled resin composition capable of welding a molded article to other parts, a welded molded article obtained therefrom, and a resin molded article using the same.

Means for Solving the Problems

[0007] The inventors of the present invention added zinc fatty acid, fatty acid, and paraffin oil in predetermined amounts to an inorganic powder-filled resin composition containing a thermoplastic resin and inorganic powder, and set the content mass ratio of zinc fatty acid and fatty acid within a specific range, thereby finding that a molded article can be welded to other parts and the bonding strength is sufficiently high, and completed the present invention.

[0008] One aspect of the present invention provides the following inorganic powder-filled resin composition. [1] An inorganic powder-filled resin composition containing a thermoplastic resin containing a propylene-α-olefin random copolymer, inorganic powder, zinc fatty acid having 15 to 20 carbon atoms, fatty acid having 15 to 20 carbon atoms, and paraffin oil, wherein the content mass ratio of the thermoplastic resin and the inorganic powder is 50:50 to 10:90, the content of the zinc fatty acid is 0.1% by mass or more and 0.9% by mass or less, the content of the fatty acid is 0.2% by mass or more and 1.8% by mass or less, the content mass ratio of the zinc fatty acid and the fatty acid is 10:30 to 10:15, and the content of the paraffin oil is 0.5% by mass or more and 3.5% by mass or less. [2] The inorganic powder-filled resin composition according to [1], further containing 0.1% by mass or more and 0.9% by mass or less of a polyethylene-based wax. [3] The inorganic powder-filled resin composition according to [1] or [2], wherein the zinc fatty acid is zinc stearate and the fatty acid is stearic acid. [4] The inorganic powder-filled resin composition according to any one of [1] to [3], wherein the inorganic powder is calcium carbonate powder. [5] The inorganic powder-filled resin composition according to [4], wherein the calcium carbonate powder is heavy calcium carbonate powder. [6] The inorganic powder-filled resin composition according to [5], wherein the average particle diameter of the heavy calcium carbonate powder is 0.7 μm or more and 6.0 μm or less.

[0009] One aspect of the present invention provides a molded article for welding and a resin molded article described below. [7] A molded article of the inorganic powder-filled resin composition according to any one of [1] to [6] above, having a welding region for welding to other parts by a welding method, the molded article for welding. [8] The welding region is a region for welding to other parts by any welding method selected from the group consisting of ultrasonic welding method, vibration welding method, spin welding method, injection welding method, microwave welding method, hot plate welding method, and hot air welding method. The molded article for welding according to [7]. [9] A resin molded article including the molded article for welding according to [7] or [8] and other parts joined to the welding region of the molded article for welding. [Effect of the Invention]

[0010] According to the present invention, there are provided an inorganic powder-filled resin composition capable of welding a molded article to other parts, a molded article for welding obtained therefrom, and a resin molded article using the same. [Brief Description of the Drawings]

[0011]

Figure 1

[0012] Hereinafter, an embodiment of the present invention will be described in detail. However, the present invention is not limited to the embodiment. In addition, in this specification, a numerical range represented by "~" means a range including the numerical values described before and after "~" as the lower limit value and the upper limit value.

[0013] 1. Inorganic powder-filled resin composition The inorganic powder-filled resin composition of the present embodiment (hereinafter, also simply referred to as "resin composition") contains a thermoplastic resin containing a propylene-α-olefin random copolymer, an inorganic powder, zinc fatty acid having 15 to 20 carbon atoms, a fatty acid having 15 to 20 carbon atoms, and paraffin oil. Further, in the resin composition, the content mass ratio of the thermoplastic resin and the inorganic powder is 50:50 to 10:90, the content of zinc fatty acid is 0.1% by mass or more and 0.9% by mass or less, and the content of the fatty acid is 0.2% by mass or more and 1.8% by mass or less. Further, the content mass ratio of zinc fatty acid and fatty acid is 10:30 to 10:15, and the content of paraffin oil is 0.5% by mass or more and 3.5% by mass or less.

[0014] As described above, in a resin composition in which the content of the inorganic powder is very large with respect to the content of the thermoplastic resin, the amount of the thermoplastic resin in the resin composition is small, and it is difficult to join the molded product to other parts by welding. In this specification, "welding" is a method of joining two parts, which means melting the welding region of at least one part and joining it to the other part. In the resin composition of the present embodiment, as described above, it contains zinc fatty acid, fatty acid, and paraffin oil in a predetermined amount. When the resin composition contains paraffin oil in this way, it becomes easy to plasticize the thermoplastic resin at a relatively low temperature in the molded product. That is, the fluidity of the thermoplastic resin can be increased even at a relatively low temperature, and the weldability of the molded product is improved. Further, when the resin composition contains zinc fatty acid and fatty acid in a predetermined ratio, the weldability of the molded product of the resin composition is significantly enhanced. Although the mechanism is not clear, it is considered that the weldability of the molded product is enhanced by the interaction between zinc fatty acid and fatty acid between the thermoplastic resin and the inorganic powder.

[0015] Note that the resin composition of the present invention may further contain components other than those described above. Hereinafter, each component contained in the resin composition of the present invention, its content, and further the manufacturing method and the like will be described in detail.

[0016] (Thermoplastic resin) The thermoplastic resin of this embodiment only needs to contain a propylene-α-olefin random copolymer as the main component, and may partially contain resins other than the propylene-α-olefin random copolymer as long as the objectives and effects of this embodiment are not impaired. In this specification, "containing a propylene-α-olefin random copolymer as the'main component'" means that the amount of the propylene-α-olefin random copolymer in the thermoplastic resin is 80% by mass or more based on the total amount of the thermoplastic resin. The amount of the propylene-α-olefin random copolymer in the thermoplastic resin is preferably 90% by mass or more, and more preferably 95% by mass or more.

[0017] In addition, in this specification, the propylene-α-olefin random copolymer refers to a polymer in which the constitutional units of α-olefin are randomly distributed in a polymer chain composed of a large number of constitutional units derived from propylene. The propylene-α-olefin random copolymer may be a binary random copolymer of propylene and one kind of α-olefin, or a random copolymer of propylene and two or more kinds of α-olefins. Further, it may be a random copolymer of propylene, one or more kinds of α-olefins, and monomers other than these. In the propylene-α-olefin random copolymer, the amount of the constitutional units derived from propylene only needs to be more than 50% by mass based on the total amount of all constitutional units. However, the amount of the constitutional units derived from propylene is preferably 80% by mass or more, and more preferably 82% by mass or more based on the total amount of all constitutional units. Also, the constitutional units derived from propylene are preferably 98% by mass or less, and more preferably 96% by mass or less based on the total amount of all constitutional units. When the amount of the propylene constitutional units is sufficiently large, it is easy to obtain a molded product with high strength and excellent shape stability.

[0018] Here, the steric structure of the polypropylene chain (a region continuously containing structural units derived from propylene) is not particularly limited. For example, as the triad tacticity, it may contain any of an isotactic structure, a syndiotactic structure, and an atactic structure. However, it is preferable that at least a part of the polypropylene chain contains an isotactic structure. Thereby, since the propylene-α-olefin random copolymer can form a crystalline region, it becomes easier to exhibit further toughness and shape stability. The triad tacticity is 13 identifiable by, for example, 13C-NMR.

[0019] On the other hand, examples of the α-olefin include ethylene and α-olefins having 4 to 10 carbon atoms. More specifically, ethylene, 1-butene, isobutylene, 1-pentene, 3-methyl-1-butene, 1-hexene, 3,4-dimethyl-1-butene, 1-heptene, 3-methyl-1-hexene, and 1-octene are included. The total amount of the constituent units derived from the α-olefin in the propylene-α-olefin random copolymer may be less than 50% by mass based on the total amount of all the constituent units, preferably 2% by mass or more, and more preferably 4% by mass or more. Also, it is preferably 20% by mass or less, and more preferably 18% by mass or less based on the total amount of all the constituent units. When the total amount of the constituent units derived from the α-olefin is 2% by mass or more, it becomes easier to adjust the melting point and crystallinity of the propylene-α-olefin random copolymer, and the weldability of the molded product is more likely to be enhanced. On the other hand, when the amount of the constituent units derived from the α-olefin is 20% by mass or less, it becomes easier to obtain a molded product having high strength and excellent shape stability.

[0020] Other monomers that may be copolymerized with propylene or α-olefins are not particularly limited as long as they do not impair the object and effects of the present embodiment. Examples of other monomers include diene monomers such as 1,4-hexadiene, 1,6-octadiene, 5-methyl-1,4-hexadiene, 3,7-dimethyl-1,6-octadiene, dicyclopentadiene (DCPD), ethylidene norbornene (ENB), norbornadiene, 5-vinyl-2-norbornene; acid (or acid anhydride) modified olefins such as maleic anhydride modified olefin; (meth)acrylates such as methyl (meth)acrylate; and the like. When the propylene-α-olefin random copolymer contains structural units derived from other monomers, the amount thereof is preferably less than the amount of the structural units derived from the α-olefin. Specifically, it is preferably 0.1% by mass or more and 10% by mass or less, more preferably 0.5% by mass or more and 8% by mass or less, based on the total amount of all the structural units of the propylene-α-olefin random copolymer. When the propylene-α-olefin random copolymer contains structural units derived from other monomers, it becomes easier to adjust the physical properties and processability of the resin composition and molded article.

[0021] Preferred specific examples of the above propylene-α-olefin random copolymer include propylene-ethylene copolymer, propylene-butylene-ethylene copolymer, and the like. However, the propylene-α-olefin random copolymer that can be used in the present embodiment is not limited thereto. Further, the thermoplastic resin may contain only one kind of the propylene-α-olefin random copolymer or may contain two or more kinds.

[0022] Here, the weight average molecular weight of the above propylene-α-olefin random copolymer is not particularly limited, but is usually preferably 20,000 to 5,000,000, more preferably 50,000 to 1,000,000, and even more preferably 70,000 to 1,000,000. The weight average molecular weight is a value measured by gel permeation chromatography (GPC) and is a polyethylene-equivalent value. Further, the density of the propylene-α-olefin random copolymer is 0.84 to 0.92 g / cm 3is preferred, and 0.85 to 0.91 g / cm 3 is more preferred. Further, the crystallinity of the propylene-α-olefin random copolymer is preferably 0.5 to 40%, more preferably 20 to 30%.

[0023] The melt flow rate (2.16 kg load, 230 °C) measured in accordance with ASTM D1238 of the propylene-α-olefin random copolymer is preferably 0.1 to 90 g / 10 min, more preferably 0.5 to 30 g / 10 min. Further, the melting point of the propylene-α-olefin random copolymer is preferably 40 to 180 °C, more preferably 80 to 160 °C, and even more preferably 100 to 140 °C. When the propylene-α-olefin random copolymer has such physical properties, the weldability of the resulting molded product is more likely to be improved.

[0024] The thermoplastic resin may further contain a resin other than the propylene-α-olefin random copolymer as described above. Examples of the resin other than the propylene-α-olefin random copolymer include thermoplastic resins such as poly(meth)acrylic acid (ester), polyvinyl acetate, polyacrylonitrile, polystyrene, ABS resin, polycarbonate, polyamide, polyvinyl alcohol, petroleum hydrocarbon resin, coumarone indene resin; elastomers such as styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-butadiene-ethylene copolymer, styrene-isoprene-ethylene copolymer, acrylonitrile-butadiene copolymer, fluorine-based elastomer; are included.

[0025] The content of the thermoplastic resin in the resin composition may be in the range where the mass ratio of the thermoplastic resin to the inorganic powder is 50:50 to 10:90 as described above. The total amount of the thermoplastic resin is more preferably 15 parts by mass or more and 40 parts by mass or less, and more preferably 18 parts by mass or more and 30 parts by mass or less with respect to 100 parts by mass of the total amount of the thermoplastic resin and the inorganic powder. When the amount of the thermoplastic resin is within this range, the weldability of the resulting molded product is likely to be good.

[0026] In addition, the total amount of the thermoplastic resin and the inorganic powder with respect to the total amount of the resin composition is preferably 80% by mass or more and 99.2% by mass or less, more preferably 90% by mass or more and 99% by mass or less. When the total amount of the thermoplastic resin and the inorganic powder is within this range, it is easy to obtain a molded article with high strength.

[0027] (Inorganic powder) The inorganic powder may be any powder composed of an inorganic substance, and its type is selected according to the use of the resin composition. Examples of the inorganic substance include carbonates, sulfates, silicates, phosphates, borates, oxides, or hydrates thereof such as calcium, magnesium, aluminum, titanium, iron, zinc, etc. Specific examples of the inorganic substance include calcium carbonate, magnesium carbonate, zinc oxide, titanium oxide, silica, alumina, clay (such as talc and kaolin, etc.), 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. The inorganic powder may contain only one of these or two or more of them.

[0028] In addition, the shape of the inorganic powder is not particularly limited, and it may be any of particulate, flaky, granular, fibrous, etc. Also, in the case of particulate, it may be spherical as generally obtained by a synthetic method, or may be irregularly shaped as obtained by pulverizing a collected natural mineral.

[0029] Preferred examples of the inorganic powder include powders of calcium carbonate, magnesium carbonate, dolomite, zinc oxide, titanium oxide, silica, alumina, clay, talc, kaolin, aluminum hydroxide, and magnesium hydroxide, and calcium carbonate powder is particularly preferred. The calcium carbonate may be one prepared by a synthetic method, so-called light calcium carbonate. On the other hand, it may be so-called heavy calcium carbonate obtained by mechanically pulverizing and classifying a natural raw material mainly composed of CaCO3 such as limestone. Furthermore, a combination of light calcium carbonate and heavy calcium carbonate may be used. In the present embodiment, it is particularly preferred that the inorganic powder contains heavy calcium carbonate powder. Note that heavy calcium carbonate is clearly distinguished from synthetic calcium carbonate produced by a chemical precipitation reaction or the like. The pulverization method includes a dry method and a wet method, and the dry method is preferred.

[0030] Unlike light calcium carbonate powder obtained by a synthetic method or the like, the formation of heavy calcium carbonate powder is carried out by a pulverization process. Therefore, the irregularity on the powder surface is large, and the specific surface area is larger than that of light calcium carbonate powder. Therefore, when the resin composition contains the heavy calcium carbonate powder together with the above thermoplastic resin, the contact interface between them becomes large, and the heavy calcium carbonate is likely to be uniformly dispersed in the resin composition. The specific surface area of the heavy calcium carbonate powder depends on its average particle diameter and the like, but is preferably 3,000 cm 2 / g or more and 35,000 cm 2 / g or less. When the specific surface area is within this range, the dispersibility of the heavy calcium carbonate powder is likely to be good. As a result, the weldability of the molded article obtained from the resin composition is likely to be further improved. Note that the above specific surface area is measured by the air permeability method.

[0031] Also, the heavy calcium carbonate powder preferably has a high degree of irregularity. A high degree of irregularity can also be represented, for example, by a low roundness. From the viewpoints of the strength and moldability of the molded product, the roundness of the heavy calcium carbonate powder is preferably 0.50 or more and 0.95 or less, more preferably 0.55 or more and 0.93 or less, and even more preferably 0.60 or more and 0.90 or less. The above-mentioned roundness is obtained from (the projected area of the particle) / (the area of a circle having the same perimeter as the projected perimeter of the particle). The method for measuring the roundness is not particularly limited. For example, the projected area and the projected perimeter of the particle may be measured from a micrograph, or may be calculated using general-purpose image analysis software.

[0032] Here, the inorganic powder may be surface-modified or may not be surface-modified. However, from the viewpoint of its dispersibility, it is preferably surface-modified. Examples of the surface modification method of the inorganic powder include physical modification methods such as plasma treatment, and chemical modification methods using coupling agents, surfactants, etc. Examples of the coupling agents that can be used in the chemical modification method include silane coupling agents and titanium coupling agents. As the surfactant, any of anionic, cationic, nonionic, and amphoteric ones can be used, and examples thereof include higher fatty acids, higher fatty acid esters, higher fatty acid amides, and higher fatty acid salts.

[0033] In addition, the average particle size of the inorganic powder is not particularly limited and is appropriately selected according to the shape and thickness of the molded product, etc. For example, it is preferably 0.5 μm or more and 9.0 μm or less, more preferably 0.7 μm or more and 6.0 μm or less, and even more preferably 1.0 μm or more and 4.0 μm or less. Note that the average particle size of the inorganic powder in this specification refers to the value calculated from the measurement result of the specific surface area by the air permeability method according to JIS M-8511. As an example of the measuring instrument, the specific surface area measuring device SS-100 type manufactured by Shimadzu Corporation can be mentioned. When the average particle size of the inorganic powder is 9.0 μm or less, it becomes difficult for the inorganic powder to fall off from the molded product. Note that the inorganic powder preferably does not contain particles having a particle size of 45 μm or more in its particle size distribution. On the other hand, when the above average particle size is 0.5 μm or more, the viscosity during kneading with the thermoplastic resin is likely to fall within a desired range.

[0034] As described above, the amount of the inorganic powder in the resin composition of the present embodiment may be in the range where the mass ratio of the thermoplastic resin and the inorganic powder is 50:50 to 10:90. The amount of the inorganic powder is more preferably 60 parts by mass or more and 85 parts by mass or less, and even more preferably 70 parts by mass or more and 82 parts by mass or less with respect to 100 parts by mass of the total amount of the thermoplastic resin and the inorganic powder. When the amount of the inorganic powder is within this range, the strength of the obtained molded product is more likely to be further enhanced.

[0035] (Zinc fatty acid) The zinc fatty acid contained in the resin composition is a salt composed of a fatty acid having 15 to 20 carbon atoms and zinc. The fatty acid constituting the zinc fatty acid may be a monovalent fatty acid or a polyvalent fatty acid, but a monovalent fatty acid is preferred. Further, the fatty acid may be a saturated fatty acid or an unsaturated fatty acid, but a saturated fatty acid is preferred from the viewpoint of being likely to interact with the thermoplastic resin and the inorganic powder.

[0036] Specific examples of the zinc fatty acid include zinc palmitate and zinc stearate. The resin composition may contain only one kind of zinc fatty acid or may contain two or more kinds.

[0037] The content of zinc fatty acid relative to the total amount of the resin composition is preferably 0.1% by mass or more and 0.9% by mass or less, and more preferably 0.2% by mass or more and 0.8% by mass or less. When the content of zinc fatty acid is 0.1% by mass or more, the additive effect of zinc fatty acid, that is, the effect of improving weldability, can be obtained. On the other hand, when the content of zinc fatty acid is 0.9% by mass or less, it becomes difficult for zinc fatty acid to bleed out from the resin composition or the molded product.

[0038] (fatty acid) The fatty acid contained in the resin composition is a fatty acid having 15 to 20 carbon atoms. The fatty acid may be a monovalent fatty acid or a polyvalent fatty acid, but a monovalent fatty acid is preferred. Also, the fatty acid may be a saturated fatty acid or an unsaturated fatty acid, but a saturated fatty acid is preferred from the viewpoint of being likely to interact with the thermoplastic resin and the inorganic powder. Further, the difference in the number of carbon atoms between the fatty acid and the fatty acid constituting the above zinc fatty acid is preferably small, and the difference is preferably 2 or less, more preferably 0.

[0039] Specific examples of the fatty acid include palmitic acid, stearic acid, and mixtures thereof. The resin composition may contain only one kind of fatty acid or two or more kinds of fatty acids.

[0040] Here, the amount of the fatty acid in the resin composition may be in the range where the mass ratio of the above zinc fatty acid and the fatty acid is 10:30 to 10:15. The mass ratio is preferably 10:29 to 10:16, and more preferably 10:28 to 10:17. When the mass ratio of zinc fatty acid and fatty acid is within the above range, the weldability of the molded product is significantly improved as described above.

[0041] In addition, the content of the fatty acid relative to the total amount of the resin composition may be 0.2% by mass or more and 1.8% by mass or less, and preferably 0.4% by mass or more and 1.6% by mass or less. When the content of the fatty acid is 0.2% by mass or more, the additive effect of the fatty acid, that is, the effect of improving the weldability of the molded product, can be obtained. On the other hand, when the content of the fatty acid is 1.8% by mass or less, it becomes difficult for the fatty acid to bleed out from the resin composition or the molded product.

[0042] (Paraffin oil) The paraffin oil is not particularly limited as long as it is a paraffin oil in a liquid state at 23°C, and known paraffin oils can be used. The paraffin oil is, for example, a linear or branched hydrocarbon having 14 or more and 30 or less carbon atoms, but may partially contain cyclic hydrocarbons (naphthenes) or aromatic hydrocarbons.

[0043] The amount of paraffin oil relative to the total amount of the resin composition may be 0.5% by mass or more and 3.5% by mass or less, preferably 0.7% by mass or more and 3.3% by mass or less. When the amount of paraffin oil is 0.5% by mass or more, the paraffin oil can easily sufficiently plasticize the thermoplastic resin and improve the weldability of the molded product. On the other hand, when the amount of paraffin oil is 3.5% by mass or less, it becomes difficult for the paraffin oil to bleed out from the resin composition or the molded product.

[0044] (Polyethylene-based wax) The resin composition of this embodiment may further contain a polyethylene-based wax. The polyethylene-based wax may be a wax having polyethylene as a main component, and may be a wax containing more than 50% by mass of polyethylene, preferably containing 80% by mass or more of polyethylene, and more preferably containing 90% by mass or more of polyethylene.

[0045] The melting point of the polyethylene-based wax is not particularly limited, but the melting point is preferably 70°C or higher and 150°C or lower, and more preferably 80°C or higher and 130°C or lower. When the melting point of the polyethylene-based wax is within this range, the moldability of the resin composition is improved, or the weldability of the molded product is improved. The above melting point is a value measured in accordance with JIS K7121.

[0046] In addition, the weight average molecular weight of the polyethylene wax is not particularly limited. For example, it is preferably 1,000 or more and 10,000 or less, more preferably 1,500 or more and 9,000 or less. When the weight average molecular weight of the polyethylene wax is within this range, it becomes difficult for the polyethylene wax to bleed out from the resin composition or the molded product.

[0047] The polyethylene wax may be a commercially available product. Examples thereof include the POLYWAX series manufactured by NuCera Solutions, the Hiwax series manufactured by Mitsui Chemicals, the Excelex series manufactured by Mitsui Chemicals, the Sunwax series manufactured by Sanyo Kagaku, and the like.

[0048] The amount of the polyethylene wax with respect to the total amount of the resin composition may be 0.1% by mass or more and 0.9% by mass or less, preferably 0.2% by mass or more and 0.8% by mass or less. When the amount of the polyethylene wax is 0.1% by mass or more, the moldability of the resin composition is enhanced by the polyethylene wax. On the other hand, when the amount of the polyethylene wax is 0.9% by mass or less, it becomes difficult for the polyethylene wax to bleed out from the resin composition or the molded product.

[0049] (Other components) The resin composition may further contain components other than those described above as long as the object and effects of the present embodiment are not impaired. Examples of the components other than those described above include plasticizers, coloring materials, antioxidants, flame retardants, foaming agents, flow regulators, and the like.

[0050] Examples of the plasticizer include, for example, triethyl citrate, acetyl triethyl citrate, dibutyl phthalate, diaryl phthalate, dimethyl phthalate, diethyl phthalate, dioctyl phthalate, di(2-ethylhexyl) phthalate, di-2-methoxyethyl phthalate, dibutyl tartrate, o-benzoylbenzoic acid ester, diacetin, epoxidized soybean oil, and the like. The resin composition may contain these alone or in combination of two or more.

[0051] The coloring material may be any known organic pigment, inorganic pigment or dye. Specific examples of the coloring material include 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. The resin composition may contain any one of these alone or two or more of them.

[0052] Examples of the antioxidant include phosphorus-based antioxidants, phenolic antioxidants, and pentaerythritol-based antioxidants. The resin composition may contain any one of these alone or two or more of them. Phosphorus-based, more specifically phosphorus-based antioxidant stabilizers such as phosphite esters and phosphate esters are preferably used. Examples of the phosphite ester include triester, diester, monoester, etc. of phosphorous acid such as triphenyl phosphite, trisnonylphenyl phosphite, tris(2,4-di-t-butylphenyl) phosphite, etc.

[0053] Examples of the phosphate ester include trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, triphenyl phosphate, tricresyl phosphate, tris(nonylphenyl) phosphate, 2-ethylphenyldiphenyl phosphate, etc.

[0054] Examples of the phenolic antioxidant include α-tocopherol, butylhydroxytoluene, sinapyl alcohol, vitamin E, n-octadecyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2-t-butyl-6-(3’-t-butyl-5’-methyl-2’-hydroxybenzyl)-4-methylphenyl acrylate, 2,6-di-t-butyl-4-(N,N-dimethylaminomethyl)phenol, 3,5-di-t-butyl-4-hydroxybenzylphosphonate diethyl ester, and tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxymethyl]methane, etc.

[0055] 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. The resin composition may contain one of these alone or two or more of them.

[0056] Examples of halogen-based flame retardants include halogenated bisphenol-based compounds such as halogenated bisphenylalkane, halogenated bisphenyl ether, halogenated bisphenyl thioether, and halogenated bisphenyl sulfone; bisphenol-bis(alkyl ether)-based compounds such as brominated bisphenol A, brominated bisphenol S, chlorinated bisphenol A, and chlorinated bisphenol S. Examples of phosphorus-based flame retardants include aluminum tris(diethylphosphinic acid), 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.

[0057] Also, the above-mentioned flame retardant and flame retardant aid may be combined. Examples of flame retardant aids include antimony oxides such as antimony trioxide and antimony pentoxide, zinc oxide, iron oxide, aluminum oxide, molybdenum oxide, titanium oxide, calcium oxide, magnesium oxide, and the like.

[0058] The foaming agent is not particularly limited as long as it is a compound capable of generating bubbles by mixing or injecting into the resin composition in a molten state in a melt kneader. Examples of foaming agents include those that cause a phase change from solid to gas to generate bubbles, those that cause a phase change from liquid to gas to generate bubbles, or the gas itself.

[0059] Examples of blowing agents include aliphatic hydrocarbons such as propane, butane, pentane, hexane, and heptane; alicyclic hydrocarbons such as cyclobutane, cyclopentane, and cyclohexane; halogenated hydrocarbons such as chlorodifluoromethane, difluoromethane, trifluoromethane, trichlorofluoromethane, dichloromethane, dichlorofluoromethane, dichlorodifluoromethane, chloromethane, chloroethane, dichlorotrifluoroethane, dichloropentafluoroethane, tetrafluoroethane, difluoroethane, pentafluoroethane, trifluoroethane, dichlorotetrafluoroethane, trichlorotrifluoroethane, tetrachlorodifluoroethane, and perfluorocyclobutane; inorganic gases such as carbon dioxide, nitrogen, and air; and water.

[0060] The blowing agent may also contain an active ingredient of the blowing agent together with a carrier resin. Examples of the carrier resin include crystalline olefin resins such as crystalline propylene. Examples of the active ingredient include hydrogen carbonates. Among these, hydrogen carbonates are preferred. It is preferably a blowing agent concentrate containing a crystalline polypropylene resin as the carrier resin and a hydrogen carbonate as a thermally decomposable blowing agent.

[0061] Known fluidity modifiers can also be used. Examples of the fluidity modifiers include peroxides such as dialkyl peroxides, for example, 1,4-bis[(t-butylperoxy)isopropyl]benzene. Depending on the type of thermoplastic resin used, these peroxides can also act as crosslinking agents. Particularly when the above propylene-α-olefin copolymer has a structural unit derived from a diene, the diene may be crosslinked by the peroxide.

[0062] Examples of antistatic agents include fatty acid diethanolamides such as lauryl diethanolamide and stearyl diethanolamide; hydroxyl group-containing compounds including alcohol amine-based compounds, etc. In particular, alcohol amines such as monoethanolamine, diethanolamine, triethanolamine, etc. are preferable. Two or more antistatic agents can also be used in combination. These antistatic agents may be supported on calcium silicate, calcium carbonate, etc. Note that the range of the number of carbon atoms of the acyl group of the fatty acid diethanolamide is preferably 8 or more and 22 or less from the viewpoint of exhibiting a sufficient antistatic effect.

[0063] (Shape of the resin composition) The shape of the resin composition of the present invention is not particularly limited and can be any shape such as particulate, pellet, lump, etc. When the resin composition is in pellet form, the shape of the pellet is not particularly limited and can be any shape such as cylindrical, spherical, ellipsoidal, etc. Also, its size is not particularly limited and is appropriately selected according to the shape. For example, in the case of spherical pellets, the diameter may be 1 to 10 mm. In the case of ellipsoidal pellets, the major axis can be about 1 to 10 mm and the aspect ratio can be about 0.1 to 1.0. In the case of cylindrical pellets, the diameter can be about 1 to 10 mm and the height can be about 1 to 10 mm.

[0064] (Manufacturing method of the resin composition) The manufacturing method of the above resin composition is not particularly limited. It is only necessary that the above-mentioned thermoplastic resin, inorganic powder, zinc fatty acid, fatty acid, paraffin oil, and optionally polyethylene wax and other components can be sufficiently mixed, and for example, it can be prepared by melt-kneading. At this time, all the components may be mixed and then melt-kneaded, or only some of the components may be melt-kneaded first and the remaining components may be kneaded later. The apparatus for performing melt-kneading is not particularly limited, and general extruders, kneaders, Banbury mixers, etc. can be used. Particularly from the viewpoint of obtaining a resin composition with a uniform composition, it is preferable to knead with a twin-screw kneader.

[0065] 2. Molded articles for welding and resin molded articles This embodiment provides a welded molded article which is a molded article of the above resin composition and has a welding region for welding to other components by a welding method.

[0066] The welded molded article is obtained by molding the above resin composition by a known method. The method for molding the resin composition is not particularly limited, and examples thereof include an injection molding method, an extrusion molding method, a blow molding method, etc. Also, the shape of the welding region is not particularly limited and is appropriately selected according to the desired welding method. The shape of the welding region may be planar or curved, and may have arbitrary unevenness.

[0067] Here, examples of the method for welding the welding region of the welded molded article to other components include an ultrasonic welding method, a vibration welding method, an injection welding method, a microwave welding (high-frequency induction heating welding) method, a spin welding method, a hot plate welding method, a hot air welding method, etc. Among these, an ultrasonic welding method, a vibration welding method, an injection welding method (including die slide molding and die rotation molding), and a microwave welding method are preferable, and the ultrasonic welding method is particularly preferable from the viewpoint of obtaining a resin molded article that is simple and has high bonding strength.

[0068] In the ultrasonic welding method, the welding region of the above welded molded article and the welding region of another resin component are pressed together, and ultrasonic vibration in a direction perpendicular to the interface (pressing surface) is applied to these interfaces (pressing surfaces). As a result, frictional heat is generated at the pressing surface. Then, the thermoplastic resin in the welded molded article (welding region) and the resin in the resin component melt, and the welded molded article and the resin component are joined together integrally. The resin component welded by the ultrasonic welding method is not particularly limited, and may be a molded article of the above resin composition or a molded article of a different thermoplastic resin composition. However, from the viewpoint of obtaining a resin molded article with high integrity, it is preferable that the resin component is a molded article of the above resin composition.

[0069] In the vibration welding method, the welding region of the molded article for welding and the welding region of another resin part are pressed against each other, and vibrations in a direction parallel to the interface (pressing surface) are applied to these interfaces (pressing surfaces). As a result, frictional heat is generated at the pressing surface. Then, the thermoplastic resin in the molded article for welding and the resin in the resin part melt, and the molded article for welding and the resin part are integrally joined. The resin part welded by the vibration welding method is not particularly limited, and may be a molded article of the above resin composition, or may be a molded article of a different thermoplastic resin composition. However, from the viewpoint of obtaining a resin molded article with high integrity, it is preferable that the resin part is a molded article of the above resin composition.

[0070] In the injection welding method, the molded article for welding is placed in a mold. Then, a part is formed by injection molding so as to be continuous with the welding region of the molded article for welding. In this method, the thermoplastic resin in the molded article for welding (welding region) melts and integrates with the part formed later. The material used for injection molding in the injection welding method may be the same as the above resin composition or may be different. However, from the viewpoint of obtaining a resin molded article with high integrity, it is preferable to use the above resin composition for injection molding.

[0071] In the microwave welding method, the welding region of the molded article for welding and the welding region of another resin part are pressed against each other, and loss (dielectric loss) due to friction between molecules by a high-frequency electric field is generated at these interfaces (pressing surfaces). As a result, heat generation occurs at the above interface, the thermoplastic resin in the molded article for welding and the resin in the resin part melt, and the molded article for welding and the resin part are integrally joined. The resin part welded by the microwave welding method is not particularly limited, and may be a molded article of the above resin composition, or may be a molded article of a different thermoplastic resin composition. However, from the viewpoint of obtaining a resin molded article with high integrity, it is preferable that the resin part is a molded article of the above resin composition.

[0072] Here, the use of the above-mentioned molded article for welding and the resin molded article in which other components are joined to the welding region of the molded article for welding is not particularly limited. Examples of the use of the resin molded article include automotive parts; various parts of electrical and electronic equipment such as televisions and vacuum cleaners; housing equipment parts; various parts in the industrial field; building materials parts; toys, etc., and are all applicable to uses where conventional polypropylene-based resin compositions have been used.

Examples

[0073] The present invention will be described in detail based on examples, but the present invention is not limited to these examples.

[0074] [Materials] The following components were used in each example and comparative example. · Propylene copolymer (propylene terpolymer, manufactured by Lotte Chemical Corporation, SFC-851, propylene content 85 to 95% by mass, butylene and ethylene content 5 to 15% by mass) · Calcium bicarbonate powder (manufactured by Takehara Chemical Co., Ltd., Sunlight SL-1500, average particle diameter 2.0 μm) · Zinc stearate (manufactured by NOF Corporation, Zinc Stearate G) · Stearic acid (manufactured by Kao Corporation, Lunac S-70V) · Paraffin oil (manufactured by H&R, PIONIER1535) · Polyethylene wax (manufactured by Mitsui Chemicals, Inc., HIWAX210P) · Phenolic antioxidant (manufactured by ADEKA Corporation, Adeka Stab AO-60) · Phosphorus antioxidant (manufactured by ADEKA Corporation, Adeka Stab 2112) · Magnesium stearate

[0075] [Example 1] A propylene-α-olefin random copolymer, calcium bicarbonate powder, zinc stearate, stearic acid, paraffin oil, polyethylene wax, a phenolic antioxidant, and a phosphoric acid antioxidant were each put into a twin-screw kneading extruder (manufactured by Toyo Seiki Seisakusho Co., Ltd., T-die extrusion molding device (φ20 mm, L / D = 25)) at the composition ratios shown in Table 1 below, melt-kneaded at 200 °C, and pellets of the resin composition were obtained. Using the obtained pellets, plate-shaped samples (width 20 mm, length 100 mm, thickness 2 mm) were produced by an extrusion molding method.

[0076] [Examples 2 to 7, Comparative Examples 1 to 4, and Reference Examples] Plate-shaped samples were produced in the same manner as in Example 1, except that the composition was changed to that shown in Table 1.

[0077] [Evaluation] When two samples were ultrasonically welded, the joint strength and the elongation at break of each sample were measured by the following methods.

[0078] ·Measurement of joint strength Two plate-shaped samples prepared in each Example, Comparative Example, or Reference Example were prepared, and these were overlapped and arranged in a cross shape. In a 10 mm × 10 mm region of the overlapping part, ultrasonic waves were irradiated for 1 m second while applying pressure under the following conditions using an ultrasonic welding device (PLUS-20S manufactured by Kaijo Corporation), and the two samples were welded. Similarly, the welding time was changed to 200 m seconds or 600 m seconds, and the two samples were welded. (Welding conditions) Frequency: 20 kHz Pressure: 150 N Welding time: 1 to 600 m seconds Holding time: 500 m seconds

[0079] After welding, the two samples were pulled in a direction to separate from each other using a tensile testing machine. At this time, the load (joint strength) required to separate the two samples was measured. The results are shown in Table 1.

[0080] ·Measurement of elongation at break The elongation at break of each sample was measured in accordance with ISO 527. The results are shown in Table 1.

Table 1

[0081] [Discussion] As shown in Table 1 above, when the content of zinc stearate is 0.1% by mass or more and 0.9% by mass or less, the content of stearic acid is 0.2% by mass or more and 1.8% by mass or less, the content mass ratio of zinc stearate and stearic acid is 10:30 to 10:15, and the amount of paraffin oil is 0.5% by mass or more and 3.5% by mass or less (Examples 1 to 7), the bonding strength after ultrasonic welding was high in all cases. In particular, in these examples, the bonding strength between samples could be increased in a shorter time compared to the case of simply welding polypropylenes (Reference Example). Furthermore, since the samples (molded products) obtained from the resin composition have excellent elongation at break, it can be said that a molded product with high strength can be obtained according to the above resin composition.

[0082] On the other hand, even if zinc stearate and stearic acid were contained, when the content mass ratio of zinc stearate and stearic acid deviated from the above range, the bonding strength decreased significantly (Comparative Examples 1 and 2). Furthermore, when the amount of paraffin oil was excessively small, the result of elongation at break deteriorated, and furthermore, the bonding strength also decreased (Comparative Example 3). Also, when magnesium stearate was used instead of zinc stearate and stearic acid, the bonding strength was low (Comparative Example 4).

[0083] [Examples 8 to 10, and Comparative Example 5] Similar to Examples 1 to 3 and Comparative Example 4, pellets of the resin composition were obtained. Using the obtained pellets, a first sample 11 having the planar shape shown in Fig. 1A (thickness: 10 mm) was produced by an extrusion molding method.

[0084] [Evaluation] The bonding strength was measured when the second sample (resin part) 12 was joined to the first sample by injection welding according to the following method.

[0085] · Measurement of bonding strength The first sample 11 was placed in a mold for producing fatigue test pieces. Then, using the same pellets as those used for producing the first sample 11, a second sample 12 having the same shape as the first sample 11 was formed by injection molding. As a result, as shown in Fig. 1B, a measurement sample in which the first sample 11 and the second sample 12 were joined in the welding region 13 was obtained. The measurement sample was pulled in the direction of separating the first sample 11 and the second sample 12 at a pulling speed of 5 mm / sec and a span interval of 50 mm, and the strength (bonding strength) at which the measurement sample broke in the welding region 13 was determined. The results are shown in Table 2.

Table 2

[0086] [Discussion] As shown in Table 2 above, when the content of zinc stearate is 0.1 mass% or more and 0.9 mass% or less, the content of stearic acid is 0.2 mass% or more and 1.8 mass% or less, the content mass ratio of zinc stearate and stearic acid is 10:30 to 10:15, and the amount of paraffin oil is 0.5 mass% or more and 3.5 mass% or less (Examples 8 to 10), the bonding strength after injection welding was high. On the other hand, when magnesium stearate was used instead of zinc stearate and stearic acid, the bonding strength was low (Comparative Example 5).

Industrial Applicability

[0087] According to the inorganic powder-filled resin composition of the present invention, a welded molded product that can be easily joined to other parts by welding, and a resin molded product in which the welded molded product is joined to other parts can be obtained. Therefore, it is very useful in the manufacture of parts and products in various industrial fields such as automotive parts, and toys.

Explanation of Signs

[0088] 11 First sample 12 Second sample 13 Welding area

Claims

1. A thermoplastic resin containing a propylene-α-olefin random copolymer, an inorganic powder, zinc fatty acid having 15 to 20 carbon atoms, fatty acid having 15 to 20 carbon atoms, paraffin oil, and comprising: wherein the mass ratio of the thermoplastic resin and the inorganic powder is 50:50 to 10:90, the content of the zinc fatty acid is 0.1% by mass or more and 0.9% by mass or less, the content of the fatty acid is 0.2% by mass or more and 1.8% by mass or less, the mass ratio of the zinc fatty acid and the fatty acid is 10:30 to 10:15, and the content of the paraffin oil is 0.5% by mass or more and 3.5% by mass or less, an inorganic powder-filled resin composition.

2. Further comprising 0.1% by mass or more and 0.9% by mass or less of a polyethylene-based wax, the inorganic powder-filled resin composition according to Claim 1.

3. wherein the zinc fatty acid is zinc stearate, the fatty acid is stearic acid, the inorganic powder-filled resin composition according to Claim 1.

4. wherein the inorganic powder is calcium carbonate powder, the inorganic powder-filled resin composition according to Claim 1.

5. wherein the calcium carbonate powder is heavy calcium carbonate powder, the inorganic powder-filled resin composition according to Claim 4.

6. wherein the average particle diameter of the heavy calcium carbonate powder is 0.7 μm or more and 6.0 μm or less, the inorganic powder-filled resin composition according to Claim 5.

7. a molded article of the inorganic powder-filled resin composition according to any one of Claims 1 to 6, having a welding area for welding to other parts by a welding method, a molded article for welding.

8. wherein the welding area is an area for welding to other parts by any welding method selected from the group consisting of ultrasonic welding method, vibration welding method, spin welding method, injection welding method, microwave welding method, hot plate welding method, and hot air welding method, the molded article for welding according to Claim 7.

9. the molded article for welding according to Claim 7, and other parts joined to the welding area of the molded article for welding, and comprising a resin molded article.

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