JP7506818B1 - Inorganic powder-filled resin composition, molded article for welding, and resin molded article - Google Patents

Abstract

[Problem] To provide an inorganic powder-filled resin composition that allows welding of molded articles. [Solution] The inorganic powder-filled resin composition that solves the above problem comprises a thermoplastic resin containing a propylene-α-olefin random copolymer, an inorganic powder, a fatty acid zinc salt having a carbon number of 15 to 20, a fatty acid having a carbon number of 15 to 20, and paraffin oil. The mass ratio of the thermoplastic resin to the inorganic powder is 50:50 to 10:90, the content of the fatty acid zinc salt is 0.1% by mass to 0.9% by mass, and the content of the fatty acid is 0.2% by mass to 1.8% by mass. The mass ratio of the fatty acid zinc salt to the fatty acid salt is 10:30 to 10:15, and the amount of the paraffin oil is 0.5% by mass to 3.5% by mass. [Selected Figure] None

Description

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

Conventionally, various products using inorganic powder-filled resin compositions in which calcium carbonate powder is highly filled into thermoplastic resins are known (for example, Patent Document 1). Such inorganic powder-filled resin compositions have the advantages of low thermal shrinkage and excellent impact resistance.

In recent years, there has been a demand for the inorganic powder-filled resin composition to be used in a wider range of applications, and consideration has been given to replacing conventional resin molded products with molded products obtained from the inorganic powder resin composition. This has led to a demand for the molded product obtained from the inorganic powder-filled resin composition to be combined and integrated with other parts, or for the molded product to be joined to other parts by welding.

JP 2023-77472 A

However, in the inorganic powder-filled resin composition described in Patent Document 1, the amount of inorganic powder relative to the amount of thermoplastic resin is very large. This makes it difficult to join a molded product obtained from the inorganic powder-filled resin composition to other parts by welding, and even if joining is possible, it is difficult to sufficiently increase the strength.

The present invention has been made in consideration of the problems of the conventional technology described above. Specifically, the object is to provide an inorganic powder-filled resin composition that allows a molded article to be welded to another part, a molded article for welding obtained from the composition, and a resin molded article using the composition.

The inventors discovered that by adding predetermined amounts of fatty acid zinc, fatty acid, and paraffin oil to an inorganic powder-filled resin composition containing a thermoplastic resin and inorganic powder in a predetermined ratio, and by setting the mass ratio of the fatty acid zinc and fatty acid within a specific range, it is possible to weld a molded product to other parts, and that the bonding strength is sufficiently high, thus completing the present invention.

One aspect of the present invention provides an inorganic powder-filled resin composition as described below.
[1] An inorganic powder-filled resin composition comprising a thermoplastic resin containing a propylene-α-olefin random copolymer, an inorganic powder, a fatty acid zinc salt having a carbon number of 15 to 20, a fatty acid having a carbon number of 15 to 20, and paraffin oil, wherein the mass ratio of the thermoplastic resin to the inorganic powder is 50:50 to 10:90, the content of the fatty acid zinc salt 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 of the fatty acid zinc salt to 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 comprising 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 fatty acid zinc salt 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 ground calcium carbonate powder.
[6] The inorganic powder-filled resin composition according to [5], wherein the average particle size of the ground calcium carbonate powder is 0.7 μm or more and 6.0 μm or less.

One aspect of the present invention provides the following weldable molded article and resin molded article.
[7] A molded article for welding, which is a molded article of the inorganic powder-filled resin composition according to any one of [1] to [6] above, and has a welding region for welding to another part by a welding method.
[8] The weldable molded product according to [7], wherein the weldable region is a region for welding to another component by any one of a welding methods selected from the group consisting of ultrasonic welding, vibration welding, spin welding, injection welding, microwave welding, hot plate welding, and hot air welding.
[9] A resin molded product comprising the molded product for welding according to [7] or [8] above, and another component joined to the welding region of the molded product for welding.

The present invention provides an inorganic powder-filled resin composition that can be used to weld molded products to other parts, a molded product for welding obtained from the composition, and a resin molded product using the composition.

1A and 1B are diagrams for explaining the shape of a measurement sample prepared in an example.

One embodiment of the present invention is described in detail below. However, the present invention is not limited to this embodiment. In addition, in this specification, a numerical range expressed using "~" means a range that includes the numerical values written before and after "~" as the lower and upper limits.

1. Inorganic Powder-Filled Resin Composition The inorganic powder-filled resin composition of this embodiment (hereinafter also simply referred to as "resin composition") contains a thermoplastic resin containing a propylene-α-olefin random copolymer, an inorganic powder, a fatty acid zinc salt having a carbon number of 15 to 20, a fatty acid having a carbon number of 15 to 20, and paraffin oil. In addition, in this resin composition, 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 salt is 0.1 mass% to 0.9 mass%, and the content of the fatty acid is 0.2 mass% to 1.8 mass%. In addition, the content mass ratio of the fatty acid zinc salt and the fatty acid salt is 10:30 to 10:15, and the content of the paraffin oil is 0.5 mass% to 3.5 mass%.

As described above, in a resin composition in which the content of inorganic powder is very high relative to the content of thermoplastic resin, the amount of 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" refers to a method of joining two parts, in which the welding area of at least one part is melted and joined to the other part. In the resin composition of this embodiment, as described above, a predetermined amount of fatty acid zinc, fatty acid, and paraffin oil is contained. When the resin composition contains paraffin oil in this way, the thermoplastic resin in the molded product is easily plasticized at a relatively low temperature. In other words, the fluidity of the thermoplastic resin can be increased even at a relatively low temperature, and the weldability of the molded product is improved. In addition, when the resin composition contains fatty acid zinc and fatty acid in a predetermined ratio, the weldability of the molded product of the resin composition is significantly improved. Although the mechanism is unclear, it is thought that the fatty acid zinc and fatty acid interact with the thermoplastic resin and the inorganic powder to increase the weldability of the molded product.

The resin composition of the present invention may further contain components other than those described above. Below, the components contained in the resin composition of the present invention, their contents, and the manufacturing method, etc. will be described in detail.

(Thermoplastic resin)
The thermoplastic resin of this embodiment may contain a propylene-α-olefin random copolymer as a main component, and may contain a resin other than the propylene-α-olefin random copolymer as long as the purpose and effect of this embodiment are not impaired. In this specification, containing a propylene-α-olefin random copolymer as a "main component" means that the amount of the propylene-α-olefin random copolymer in the thermoplastic resin is 80% by mass or more with respect to 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, more preferably 95% by mass or more.

In this specification, the propylene-α-olefin random copolymer refers to a polymer in which α-olefin structural units are randomly distributed in a polymer chain composed of a large number of propylene-derived structural units. The propylene-α-olefin random copolymer may be a binary random copolymer of propylene and one type of α-olefin, or a ternary or higher random copolymer of propylene and two or more types of α-olefin. It may also be a ternary or higher random copolymer of propylene, one or more types of α-olefin, and a monomer other than these. In the propylene-α-olefin random copolymer, the amount of propylene-derived structural units may be more than 50% by mass relative to the total amount of all structural units. However, the amount of propylene-derived structural units is preferably 80% by mass or more, more preferably 82% by mass or more, relative to the total amount of all structural units. The amount of propylene-derived structural units is preferably 98% by mass or less, more preferably 96% by mass or less, relative to the total amount of all structural units. If the amount of propylene structural units is sufficiently large, it becomes easier to obtain molded products that are strong and have excellent shape stability.

Here, the three-dimensional structure of the polypropylene chain (the region containing a continuous propylene-derived structural unit) is not particularly limited, and may contain, for example, any of an isotactic structure, a syndiotactic structure, and an atactic structure as triad tacticity. However, it is preferable that at least a part of the polypropylene chain contains an isotactic structure. This allows the propylene-α-olefin random copolymer to form a crystalline region, which makes it easier to exhibit further toughness and shape stability. The triad tacticity can be identified by ¹³ C-NMR or the like.

On the other hand, examples of the α-olefins 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. The total amount of α-olefin-derived structural units in the propylene-α-olefin random copolymer may be less than 50% by mass relative to the total amount of all structural units, but is preferably 2% by mass or more, and more preferably 4% by mass or more. In addition, it is preferably 20% by mass or less, and more preferably 18% by mass or less, relative to the total amount of all structural units. If the total amount of α-olefin-derived structural units 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 further improved. On the other hand, if the amount of structural units derived from α-olefin is 20% by mass or less, it becomes easier to obtain molded products with high strength and excellent shape stability.

In addition, other monomers that may be copolymerized with propylene or α-olefins are not particularly limited as long as they do not impair the purpose and effect of this 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, and 5-vinyl-2-norbornene; acid (or acid anhydride) modified olefins such as maleic anhydride modified olefins; (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 of the structural units is preferably less than the amount of structural units derived from α-olefins. Specifically, the amount of the structural units of the propylene-α-olefin random copolymer is preferably 0.1% by mass or more and 10% by mass or less, and more preferably 0.5% by mass or more and 8% by mass or less. 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 products.

Preferred specific examples of the propylene-α-olefin random copolymer include propylene-ethylene copolymer and propylene-butylene-ethylene copolymer. However, the propylene-α-olefin random copolymer usable in this embodiment is not limited to these. In addition, the thermoplastic resin may contain only one type of propylene-α-olefin random copolymer, or may contain two or more types.

Here, the weight average molecular weight of the 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. Furthermore, the density of the propylene-α-olefin random copolymer is preferably 0.84 to 0.92 g/cm ³ , and more preferably 0.85 to 0.91 g/cm ^3. Furthermore, the crystallinity of the propylene-α-olefin random copolymer is preferably 0.5 to 40%, and more preferably 20 to 30%.

The melt flow rate (2.16 kg load, 230°C) of the propylene-α-olefin random copolymer measured in accordance with ASTM D1238 is preferably 0.1 to 90 g/10 min, more preferably 0.5 to 30 g/10 min. Furthermore, 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 tends to be even better.

The thermoplastic resin may further contain a resin other than the propylene-α-olefin random copolymer, as described above. Examples of resins 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, and coumarone-indene resin; and elastomers such as styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-butadiene-ethylene copolymer, styrene-isoprene-ethylene copolymer, acrylonitrile-butadiene copolymer, and fluorine-based elastomer.

As described above, 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. The total amount of the thermoplastic resin is 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, per 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.

The total amount of the thermoplastic resin and inorganic powder relative to the total amount of the resin composition is preferably 80% by mass or more and 99.2% by mass or less, and more preferably 90% by mass or more and 99% by mass or less. When the total amount of the thermoplastic resin and inorganic powder is within this range, it becomes easier to obtain a molded product with high strength.

(Inorganic powder)
The inorganic powder may be any powder made of an inorganic substance, and the type of the inorganic powder is selected according to the application of the resin composition. Examples of the inorganic substance include carbonates, sulfates, silicates, phosphates, borates, oxides, or hydrates of calcium, magnesium, aluminum, titanium, iron, zinc, etc., or hydrates thereof. Specific examples of the inorganic substance include calcium carbonate, magnesium carbonate, zinc oxide, titanium oxide, silica, alumina, clay (e.g., talc, 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.

The shape of the inorganic powder is not particularly limited, and may be any of particles, flakes, granules, fibers, etc. In the case of particles, the powder may be spherical, as is generally obtained by synthetic methods, or irregularly shaped, as is obtained by crushing collected natural minerals.

Preferred examples of inorganic powders include calcium carbonate, magnesium carbonate, dolomite, zinc oxide, titanium oxide, silica, alumina, clay, talc, kaolin, aluminum hydroxide, and magnesium hydroxide powders, and calcium carbonate powder is particularly preferred. Calcium carbonate may be prepared by a synthetic method, that is, so-called light calcium carbonate. On the other hand, it may be so-called heavy calcium carbonate obtained by mechanically grinding and classifying natural raw materials mainly composed of CaCO ₃ such as limestone. Furthermore, it may be a combination of light calcium carbonate and heavy calcium carbonate. In this 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 chemical precipitation reaction or the like. There are dry and wet grinding methods, and the dry method is preferred.

Unlike light calcium carbonate powder obtained by a synthetic method, the heavy calcium carbonate powder is formed by a pulverization process. Therefore, the powder surface has a large shapelessness, 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 thermoplastic resin, the contact interface between them becomes large, and the heavy calcium carbonate is easily dispersed uniformly in the resin composition. The specific surface area of the heavy calcium carbonate powder is preferably 3,000 cm ² /g or more and 35,000 cm ² /g or less, although it depends on the average particle size, etc. When the specific surface area is within this range, the dispersibility of the heavy calcium carbonate powder is easily improved. As a result, the adhesion of the molded product obtained from the resin composition is easily improved. The specific surface area is measured by an air permeability method.

It is also preferable that the ground calcium carbonate powder has high irregularity. High irregularity can be expressed, for example, by low circularity. From the viewpoint of the strength and moldability of the molded product, the roundness of the ground calcium carbonate powder is preferably 0.50 to 0.95, more preferably 0.55 to 0.93, and even more preferably 0.60 to 0.90. The roundness is calculated by (projected area of a particle)/(area of a circle having the same perimeter as the projected perimeter of a particle). The method for measuring the roundness is not particularly limited, and for example, the projected area and projected perimeter of a particle may be measured from a micrograph, or may be calculated using general-purpose image analysis software.

Here, the inorganic powder may be surface-modified or may not be surface-modified, but from the viewpoint of dispersibility, surface-modified is preferable. Examples of surface modification methods for inorganic powders include physical modification methods using plasma treatment, etc., and chemical modification methods using coupling agents, surfactants, etc. Examples of coupling agents that can be used in chemical modification methods include silane coupling agents and titanium coupling agents. As surfactants, any of anionic, cationic, nonionic, and amphoteric surfactants can be used, and examples include higher fatty acids, higher fatty acid esters, higher fatty acid amides, and higher fatty acid salts.

The average particle size of the inorganic powder is not particularly limited and is appropriately selected depending on the shape and thickness of the molded product, but is preferably 0.5 μm to 9.0 μm, more preferably 0.7 μm to 6.0 μm, and more preferably 1.0 μm to 4.0 μm. The average particle size of the inorganic powder in this specification refers to a value calculated from the measurement results of the specific surface area by the air permeation method according to JIS M-8511. An example of a measuring instrument is the specific surface area measuring device SS-100 type manufactured by Shimadzu Corporation. If the average particle size of the inorganic powder is 9.0 μm or less, the inorganic powder is less likely to fall off from the molded product. It is preferable that the inorganic powder does not contain particles with a particle size of 45 μm or more in its particle size distribution. On the other hand, if the average particle size is 0.5 μm or more, the viscosity when kneaded with the thermoplastic resin is likely to fall within the desired range.

The amount of inorganic powder in the resin composition of this embodiment may be in the range of 50:50 to 10:90 in terms of the mass ratio of the thermoplastic resin and the inorganic powder, as described above. The amount of inorganic powder is preferably 60 parts by mass or more and 85 parts by mass or less, and more preferably 70 parts by mass or more and 82 parts by mass or less, per 100 parts by mass of the total amount of the thermoplastic resin and the inorganic powder. When the amount of inorganic powder is within this range, the strength of the obtained molded product is likely to be further increased.

(Zinc fatty acid)
The fatty acid zinc contained in the resin composition is a salt of zinc and a fatty acid having 15 to 20 carbon atoms. The fatty acid constituting the fatty acid zinc may be a monovalent fatty acid or a polyvalent fatty acid, but is preferably a monovalent fatty acid. The fatty acid may be a saturated fatty acid or an unsaturated fatty acid, but is preferably a saturated fatty acid from the viewpoint of easy interaction with thermoplastic resins and inorganic powders.

Specific examples of the zinc fatty acid include zinc palmitate and zinc stearate. The resin composition may contain only one type of zinc fatty acid, or may contain two or more types.

The content of fatty acid zinc 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. If the content of fatty acid zinc is 0.1% by mass or more, the effect of adding fatty acid zinc, that is, the effect of improving weldability, can be obtained. On the other hand, if the content of fatty acid zinc is 0.9% by mass or less, fatty acid zinc is less likely to bleed out from the resin composition or molded product.

(fatty acid)
The fatty acid contained in the resin composition is a fatty acid having a carbon number of 15 or more and 20 or less. The fatty acid may be a monovalent fatty acid or a polyvalent fatty acid, but is preferably a monovalent fatty acid. The fatty acid may be a saturated fatty acid or an unsaturated fatty acid, but is preferably a saturated fatty acid from the viewpoint of easy interaction with thermoplastic resins and inorganic powders. The carbon number of the fatty acid is preferably small compared to the carbon number of the fatty acid constituting the fatty acid zinc, and the difference is preferably 2 or less, more preferably 0.

Specific examples of the fatty acid include palmitic acid, stearic acid, and mixtures thereof. The resin composition may contain only one type of fatty acid, or may contain two or more types.

The amount of fatty acid in the resin composition may be in the range where the content mass ratio of the fatty acid zinc to 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 content mass ratio of the fatty acid zinc to the fatty acid is in this range, the weldability of the molded product is significantly improved as described above.

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. If the content of the fatty acid is 0.2% by mass or more, the effect of adding the fatty acid, that is, the effect of improving the weldability of the molded product, can be obtained. On the other hand, if the content of the fatty acid is 1.8% by mass or less, the fatty acid is less likely to bleed out from the resin composition or molded product.

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

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, and 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, thereby improving the weldability of the molded product. On the other hand, when the amount of paraffin oil is 3.5% by mass or less, the paraffin oil is less likely to bleed out from the resin composition or molded product.

(Polyethylene wax)
The resin composition of the present embodiment may further contain a polyethylene-based wax. The polyethylene-based wax may be a wax containing polyethylene as a main component, and may be a wax containing more than 50% by mass of polyethylene, but preferably contains 80% by mass or more of polyethylene, and more preferably contains 90% by mass or more of polyethylene.

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

The weight average molecular weight of the polyethylene wax is not particularly limited, and is preferably from 1,000 to 10,000, and more preferably from 1,500 to 9,000. When the weight average molecular weight of the polyethylene wax is within this range, the polyethylene wax is less likely to bleed out from the resin composition or molded product.

The polyethylene wax may be a commercially available product, examples of which include the POLYWAX series manufactured by NuCera Solutions, the Hiwax series manufactured by Mitsui Chemicals, the Excelex series manufactured by Mitsui Chemicals, and the Sunwax series manufactured by Sanyo Scientific.

The amount of polyethylene wax relative to the total amount of the resin composition may be 0.1% by mass or more and 0.9% by mass or less, and preferably 0.2% by mass or more and 0.8% by mass or less. If the amount of polyethylene wax is 0.1% by mass or more, the polyethylene wax is likely to improve the moldability of the resin composition. On the other hand, if the amount of polyethylene wax is 0.9% by mass or less, the polyethylene wax is less likely to bleed out from the resin composition or molded product.

(Other ingredients)
The resin composition may further contain components other than those described above, provided that the objects and effects of the present embodiment are not impaired. Examples of the components other than those described above include plasticizers, colorants, antioxidants, flame retardants, foaming agents, flow control agents, etc.

Examples of plasticizers 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-benzoyl benzoic acid ester, diacetin, epoxidized soybean oil, etc. The resin composition may contain these alone or in combination.

The coloring material may be any of the known organic or inorganic pigments or dyes. Specific examples of coloring materials include organic pigments such as azo, anthraquinone, phthalocyanine, quinacridone, isoindolinone, diosadin, perinone, quinophthalone, and perylene pigments, and inorganic pigments such as ultramarine, titanium oxide, titanium yellow, iron oxide (red oxide), chromium oxide, zinc oxide, and carbon black. The resin composition may contain one of these alone or two or more of them.

Examples of antioxidants include phosphorus-based antioxidants, phenol-based antioxidants, and pentaerythritol-based antioxidants. The resin composition may contain these antioxidants alone or in combination. Phosphorus-based, more specifically phosphorus-based antioxidant stabilizers such as phosphite esters and phosphate esters, are preferably used. Examples of phosphite esters include triesters, diesters, and monoesters of phosphorous acid, such as triphenyl phosphite, trisnonylphenyl phosphite, and tris(2,4-di-t-butylphenyl) phosphite.

Examples of phosphate esters include trimethyl phosphate, triethyl phosphate, tributyl phosphate, trioctyl phosphate, triphenyl phosphate, tricresyl phosphate, tris(nonylphenyl)phosphate, and 2-ethylphenyldiphenyl phosphate.

Examples of phenolic antioxidants include α-tocopherol, butyl hydroxytoluene, 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-methylphenylacrylate, 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.

The flame retardant is not particularly limited, but may be, for example, a halogen-based flame retardant or a non-phosphorus-based halogen-based flame retardant such as a phosphorus-based flame retardant or a metal hydrate. The resin composition may contain one of these alone or two or more of them.

Examples of halogen-based flame retardants include halogenated bisphenol compounds such as halogenated bisphenylalkanes, halogenated bisphenylethers, halogenated bisphenylthioethers, and halogenated bisphenylsulfones, and bisphenol-bis(alkyl ether) 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(diethylphosphinate), bisphenol A bis(diphenyl phosphate), triarylisopropyl phosphate, cresyl di-2,6-xylenyl phosphate, and aromatic condensed phosphate esters. Examples of metal hydrates include aluminum trihydrate, magnesium dihydroxide, or a combination thereof.

The flame retardant may be combined with a flame retardant assistant. Examples of flame retardant assistants include antimony oxides such as antimony trioxide and antimony pentoxide, zinc oxide, iron oxide, aluminum oxide, molybdenum oxide, titanium oxide, calcium oxide, magnesium oxide, etc.

There are no particular limitations on the foaming agent, so long as it is a compound capable of generating bubbles when mixed or pressed into a resin composition in a molten state in a melt kneader. Examples of foaming agents include those that change phase from solid to gas to generate bubbles, those that change phase from liquid to gas to generate bubbles, and gas itself.

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.

The foaming agent may contain the active ingredient of the foaming agent together with the carrier resin. Examples of the carrier resin include crystalline olefin resins such as crystalline propylene. Examples of the active ingredient include bicarbonates. Of these, bicarbonates are preferred. A foaming agent concentrate containing crystalline polypropylene resin as the carrier resin and bicarbonates as the thermal decomposition type foaming agent is preferred.

As the flow control agent, known agents can be used. Examples of flow control agents 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. In particular, when the propylene-α-olefin copolymer has structural units derived from a diene, the diene may be crosslinked by the peroxide.

Examples of antistatic agents include fatty acid diethanolamides such as lauryl diethanolamide and stearyl diethanolamide; and hydroxyl group-containing compounds such as alcohol amine compounds. In particular, alcohol amines, such as monoethanolamine, diethanolamine, and triethanolamine, are preferred. Two or more types of antistatic agents can be used in combination. These antistatic agents may be supported on calcium silicate, calcium carbonate, or the like. The carbon number of the acyl group of the fatty acid diethanolamide is preferably in the range of 8 to 22 in terms of exerting a sufficient antistatic effect.

(Shape of resin composition)
The shape of the resin composition of the present invention is not particularly limited, and may be any shape such as a particulate shape, a pellet shape, or a lump shape. When the resin composition is in the form of a pellet, the shape of the pellet is not particularly limited, and may be any shape such as a cylindrical shape, a spherical shape, or an elliptical sphere. The size is also not particularly limited, and is appropriately selected according to the shape. For example, in the case of a spherical pellet, the diameter may be 1 to 10 mm. In the case of an elliptical sphere pellet, the major axis may be about 1 to 10 mm, and the aspect ratio may be about 0.1 to 1.0. In the case of a cylindrical pellet, the diameter may be about 1 to 10 mm, and the height may be about 1 to 10 mm.

(Method for producing resin composition)
The method for producing the resin composition is not particularly limited. The above-mentioned thermoplastic resin, inorganic powder, fatty acid zinc, fatty acid, paraffin oil, and, if necessary, polyethylene wax and other components may be sufficiently mixed, and may be prepared, for example, by melt kneading. At this time, all components may be mixed and then melt kneaded, or only a portion of the components may be melt kneaded first, and the remaining components may be kneaded later. The device for melt kneading is not particularly limited, and a general extruder, kneader, Banbury mixer, etc. may be used. In particular, from the viewpoint of obtaining a resin composition with a uniform composition, it is preferable to knead with a twin-screw kneader.

2. Molded article for welding and resin molded article This embodiment provides a molded article for welding, which is a molded article of the above-mentioned resin composition and has a weldable region for welding to another part by a welding method.

The molded article for welding is obtained by molding the above-mentioned resin composition by a known method. The method for molding the resin composition is not particularly limited, and examples include injection molding, extrusion molding, blow molding, etc. 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 flat or curved, and may have any irregularities.

Here, examples of methods for welding the welding area of a molded product to another part include ultrasonic welding, vibration welding, injection welding, microwave welding (high-frequency induction heating welding), spin welding, hot plate welding, hot air welding, etc. Among these, ultrasonic welding, vibration welding, injection welding (including die slide molding and die rotation molding), and microwave welding are preferred, and ultrasonic welding is particularly preferred from the viewpoint of obtaining a resin molded product that is simple and has high bonding strength.

In the ultrasonic welding method, the welding area of the above-mentioned molded product for welding and the welding area of another resin part are pressed together, and ultrasonic vibrations are applied to the interface (pressure-welding surface) between them in a direction perpendicular to the interface. This generates frictional heat at the pressure-welding surface. Then, the thermoplastic resin in the molded product for welding (welding area) and the resin in the resin part melt, and the molded product for welding and the resin part are integrally joined. There are no particular restrictions on the resin parts to be welded by the ultrasonic welding method, and they may be molded products of the above-mentioned resin composition or molded products of a different thermoplastic resin composition. However, from the viewpoint of obtaining a resin molded product with high integrity, it is preferable that the resin part is a molded product of the above-mentioned resin composition.

In the vibration welding method, the welding area of the above-mentioned molded product for welding is pressed against the welding area of another resin part, and vibration is applied to the interface (pressure-welding surface) between them in a direction parallel to the interface. This generates frictional heat at the pressure-welding surface. The thermoplastic resin in the molded product for welding and the resin in the resin part melt, and the molded product for welding and the resin part are integrally joined. There are no particular limitations on the resin parts to be welded by the vibration welding method, and they may be molded products of the above-mentioned resin composition, or may be molded products of a different thermoplastic resin composition. However, from the viewpoint of obtaining a resin molded product with high integrity, it is preferable that the resin part is a molded product of the above-mentioned resin composition.

In the injection welding method, a molded product for welding is placed in a mold. Then, a part is formed by injection molding so that it is continuous with the welding area of the molded product for welding. In this method, the thermoplastic resin in the molded product for welding (welding area) melts and becomes integrated with the part that will be formed later. The material used for injection molding in this injection welding method may be the same as the above-mentioned resin composition, or it may be different. However, from the viewpoint of obtaining a resin molded product with high integrity, it is preferable to use the above-mentioned resin composition for injection molding.

In the microwave welding method, the welding area of the above-mentioned molded product for welding is pressed against the welding area of another resin part, and a loss (dielectric loss) due to friction between molecules caused by a high-frequency electric field is generated at the interface (pressure-welded surface) between them. This generates heat at the interface, melting the thermoplastic resin in the molded product for welding and the resin in the resin part, and the molded product for welding and the resin part are integrally joined. There are no particular restrictions on the resin parts to be welded by the microwave welding method, and they may be molded products of the above-mentioned resin composition or molded products of a different thermoplastic resin composition. However, from the viewpoint of obtaining a resin molded product with high integrity, it is preferable that the resin part is a molded product of the above-mentioned resin composition.

Here, there are no particular limitations on the uses of the above-mentioned welding molded product and the resin molded product in which other parts are joined to the welding region of the welding molded product. Examples of uses of the resin molded product include automobile parts; various parts for electric and electronic devices such as televisions and vacuum cleaners; housing equipment parts; various parts in the industrial field; building material parts; toys, and the like, and it can be applied to any use in which polypropylene-based resin compositions have traditionally been used.

The present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

[material]
The following components were used in each of the examples and comparative examples.
Propylene-based copolymer (propylene-based terpolymer, manufactured by Lotte Chemical Co., Ltd., SFC-851, propylene content 85 to 95% by mass, butylene and ethylene content 5 to 15% by mass)
Calcium bicarbonate powder (Takehara Chemical Industry Co., Ltd., Sunlight SL-1500, average particle size 2.0 μm)
Zinc stearate (NOF Corporation, Zinc Stearate G)
- Stearic acid (Kao Corporation, Lunac S-70V)
・Paraffin oil (H&R, PIONIER 1535)
- Polyethylene wax (HIWAX210P, manufactured by Mitsui Chemicals)
- Phenol-based antioxidant (ADEKA Corporation, Adekastab AO-60)
Phosphorus-based antioxidant (ADEKA Corporation, Adeka STAB 2112)
·Magnesium stearate

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

[Examples 2 to 7, Comparative Examples 1 to 4, and Reference Example]
A plate-shaped sample was prepared in the same manner as in Example 1, except that the composition was changed as shown in Table 1.

[evaluation]
The bonding strength when the two samples were ultrasonically welded together and the breaking elongation of each sample were measured by the following methods.

Measurement of bonding strength Two plate-shaped samples were prepared from each of the Examples, Comparative Examples, and Reference Examples, and were arranged crosswise. An ultrasonic welding device (Kaijo Co., Ltd. PLUS-20S) was used to irradiate ultrasonic waves for 1 ms to the 10 mm x 10 mm area of the overlapping portion while applying pressure under the following conditions, to weld the two samples together. Similarly, the welding time was changed to 200 ms or 600 ms, and the two samples were welded together.
(Welding conditions)
Frequency: 20kHz
Pressure: 150N
Welding time: 1 to 600 ms Holding time: 500 ms

After welding, a force was applied to the two samples in a direction to pull them apart using a tensile tester. The load (bonding strength) required to pull the two samples apart was measured. The results are shown in Table 1.

Measurement of Breaking Elongation The breaking elongation of each sample was measured in accordance with ISO 527. The results are shown in Table 1.

[Discussion]
As shown in Table 1, when the content of zinc stearate was 0.1% by mass or more and 0.9% by mass or less, the content of stearic acid was 0.2% by mass or more and 1.8% by mass or less, the content mass ratio of zinc stearate and stearic acid was 10:30 to 10:15, and the amount of paraffin oil was 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 the samples could be increased in a shorter time than in the case of simply welding polypropylene together (Reference Example). Furthermore, since the sample (molded article) obtained from the resin composition had excellent elongation at break, it can be said that the above-mentioned resin composition can produce a molded article with high strength.

On the other hand, even if zinc stearate and stearic acid were included, when the mass ratio of the zinc stearate to stearic acid was outside the above range, the bonding strength was significantly reduced (Comparative Examples 1 and 2). Furthermore, when the amount of paraffin oil was excessively small, the results of the breaking elongation were poor and the bonding strength was also reduced (Comparative Example 3). Furthermore, when magnesium stearate was used instead of zinc stearate and stearic acid, the bonding strength was low (Comparative Example 4).

[Examples 8 to 10 and Comparative Example 5]
Pellets of a resin composition were obtained in the same manner as in Examples 1 to 3 and Comparative Example 4. Using the obtained pellets, a first sample 11 having a planar shape (thickness 10 mm) shown in FIG. 1A was produced by extrusion molding.

[evaluation]
The bonding strength was measured when a second sample (resin part) 12 was bonded to the first sample by injection welding using the following method.

Measurement of bonding strength The first sample 11 was placed in a die for preparing a fatigue test piece. Then, the same pellets as those used for preparing the first sample 11 were used to form a second sample 12 having a similar shape to the first sample 11 by injection molding. As a result, a measurement sample was obtained in which the first sample 11 and the second sample 12 were joined at the welding region 13, as shown in FIG. 1B.
The measurement sample was pulled in a direction separating the first sample 11 and the second sample 12 at a tensile speed of 5 mm/sec and a span interval of 50 mm, and the strength (bonding strength) at which the measurement sample broke at the welding region 13 was determined. The results are shown in Table 2.

[Discussion]
As shown in Table 2 above, when the zinc stearate content was 0.1% by mass or more and 0.9% by mass or less, the stearic acid content was 0.2% by mass or more and 1.8% by mass or less, the content mass ratio of zinc stearate to stearic acid was 10:30 to 10:15, and the amount of paraffin oil was 0.5% by mass or more and 3.5% by 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).

The inorganic powder-filled resin composition of the present invention can produce a welded molded product that can be easily joined to other parts by welding, and a resin molded product in which a welded molded product is joined to other parts. Therefore, it is very useful in the manufacture of automobile parts and other industrial parts and products, toys, etc.

11 First sample 12 Second sample 13 Welding area

Claims (8)

A thermoplastic resin containing a propylene/α-olefin random copolymer;
Inorganic powder;
A zinc fatty acid having 15 to 20 carbon atoms,
A fatty acid having 15 to 20 carbon atoms;
Paraffin oil and
Including,
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% 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 fatty acid zinc and the fatty acid is 10:30 to 10:15, and the content of the paraffin oil is 0.5 mass% or more and 3.5 mass% or less ,
The inorganic powder is a calcium carbonate powder that has not been surface-modified.
Inorganic powder filled resin composition. Further containing 0.1% by mass or more and 0.9% by mass or less of a polyethylene wax;
2. The inorganic powder filled resin composition of claim 1. The fatty acid zinc is zinc stearate,
The fatty acid is stearic acid.
2. The inorganic powder filled resin composition of claim 1. The calcium carbonate powder is ground calcium carbonate powder.
2. The inorganic powder filled resin composition of claim 1 . The average particle size of the ground calcium carbonate powder is 0.7 μm or more and 6.0 μm or less.
The inorganic powder filled resin composition according to claim 4 . A molded article of the inorganic powder-filled resin composition according to any one of claims 1 to 5 ,
A welding area for welding to another component by a welding method;
Molded products for welding. The welding region is a region for welding to another component by any welding method selected from the group consisting of ultrasonic welding, vibration welding, spin welding, injection welding, microwave welding, hot plate welding, and hot air welding.
The molded article for welding according to claim 6 . The molded article for welding according to claim 6 ,
Another part joined to the welding region of the welding molded product;
A resin molded product comprising:

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