Resin molding and container

Abstract

To provide a resin molding which is excellent in oil resistance, mechanical strength and impact resistance.SOLUTION: A resin molding includes a high density polyethylene resin, and calcium carbonate, wherein when the resin molding is cut into a size of 100 mm in length, 100 mm in width and 2 mm in thickness, to manufacture a sample and the sample is immersed in 1 L of oil at a temperature of 60°C for 500 hours, a weight change rate ((B-A) / A) determined from a weight A of the sample before immersion in oil and a weight B of the sample after immersion in oil is 1% or more and 10% or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a resin molded article and a container using the resin molded article. [Background technology]

[0002] Conventionally, resin containers have been widely used for storing, transporting, and the like of goods. For example, when used for transporting goods, resin containers are required to have excellent mechanical strength. Furthermore, resin containers are generally manufactured by molding resin by a method such as injection molding. As a resin material for resin containers, polypropylene resin, which is inexpensive and has excellent mechanical strength, is widely used (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-23266 A Summary of the Invention [Problem to be solved by the invention]

[0004] Resin molded articles made of polypropylene resin are inexpensive and have excellent mechanical strength, but have the problem that they are prone to deterioration when in contact with oil for a long period of time.

[0005] On the other hand, resin molded articles made of polyethylene resin have a problem that their mechanical strength is inferior to that of polypropylene resin. In addition, when an inorganic filler is added to a polyethylene resin for the purpose of improving the mechanical strength, the impact resistance of the resin molded article is reduced. Therefore, there is a demand for a resin molded article that is excellent in all of oil resistance, mechanical strength, and impact resistance.

[0006] An object of the present invention is to provide a resin molded article having excellent oil resistance, mechanical strength, and impact resistance, and a container using the resin molded article. [Means for solving the problem]

[0007] This specification discloses the following resin molded body and container.

[0008] Item 1. A resin molded body comprising a high-density polyethylene resin and calcium carbonate, the resin molded body being cut into a size of 100 mm length × 100 mm width × 2 mm thickness to prepare a sample, the sample being immersed in 1 L of oil at a temperature of 60°C for 500 hours, the weight change rate ((B-A) / A) calculated from the weight A of the sample before immersion in the oil and the weight B of the sample after immersion in the oil being 1% or more and 10% or less.

[0009] Item 2. The resin molded product according to item 1, wherein the calcium carbonate has a volume average particle size of 0.1 μm or more and 5 μm or less.

[0010] Item 3. The resin molded body according to item 1 or 2, wherein the content of the calcium carbonate is 1% by weight or more and less than 50% by weight based on the total weight of the resin molded body.

[0011] Item 4. The BET specific surface area of ​​the calcium carbonate is 5 m 2 / g or more, 20m 2 4. The resin molded article according to any one of items 1 to 3, wherein the viscosity is 0.1 to 0.5 μm.

[0012] Item 5. The resin molded article according to any one of Items 1 to 4, wherein the high-density polyethylene resin has a weight average molecular weight of 50,000 or more and 100,000 or less.

[0013] Item 6. The resin molded product according to any one of Items 1 to 5, wherein the surface of the calcium carbonate is treated with a surface treatment agent containing a fatty acid.

[0014] Item 7. The resin molded article according to Item 6, wherein the fatty acid is at least one selected from the group consisting of palmitic acid, stearic acid, myristic acid, succinic acid, oleic acid, linoleic acid, and maleic acid.

[0015] Item 8. The resin molded article according to any one of Items 1 to 7, further comprising calcium stearate.

[0016] Item 9. The resin molded product according to item 8, wherein the content of the calcium stearate is 0.01% by weight or more and 1% by weight or less based on the total amount of the resin molded product.

[0017] Item 10. A container made of the resin molded article according to any one of items 1 to 9. Effect of the Invention

[0018] According to the present invention, it is possible to provide a resin molded article and a container using the resin molded article, which are excellent in oil resistance, mechanical strength, and impact resistance. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic perspective view showing a container according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The present invention will be described in detail below.

[0021] [Resin molding] The resin molded article of the present invention contains a high-density polyethylene resin and calcium carbonate.

[0022] Furthermore, the resin molded article of the present invention has a weight change rate of 1% or more and 10% or less, measured under the following measurement conditions.

[0023] <Measurement conditions> First, a sample is prepared by cutting the resin molded body into a size of 100 mm length x 100 mm width x 2 mm thickness. Next, the sample is immersed in 1 L of oil at 60°C for 500 hours. Next, the weight change rate ((BA) / A) is calculated from the weight A of the sample before immersion in oil and the weight B of the sample after immersion in oil.

[0024] The weight change rate ((BA) / A) is preferably 1% or more, more preferably 2% or more, and even more preferably 3% or more, and is preferably 10% or less, more preferably 9.5% or less, and even more preferably 9% or less.

[0025] Since the resin molded article of the present invention has the above-mentioned configuration, it has excellent oil resistance, mechanical strength, and impact resistance.

[0026] Conventionally, resin molded articles made of polypropylene resin, for example when used for containers and the like, are inexpensive and have excellent mechanical strength, but have a problem in that they are prone to deterioration when in contact with oil for a long period of time.

[0027] On the other hand, resin molded articles made of polyethylene resin have a problem that they are inferior in mechanical strength compared to polypropylene resin, and when an inorganic filler is added to a polyethylene resin for the purpose of improving the mechanical strength, the impact resistance of the resin molded article is reduced.

[0028] In response to this, the present inventors have focused on a resin molded article containing a high-density polyethylene resin and calcium carbonate.

[0029] In particular, the present inventors have found that a resin molded product which contains a high-density polyethylene resin and calcium carbonate and has a weight change rate ((BA) / A) measured under the above-mentioned measurement conditions of 1% or more and 10% or less has excellent oil resistance, mechanical strength, and impact resistance.

[0030] In the present invention, the average particle size of calcium carbonate is preferably 0.1 μm or more, more preferably 0.15 μm or more, and preferably 5 μm or less, more preferably 3 μm or less, and further preferably 2 μm or less.

[0031] When the average particle size of calcium carbonate is equal to or larger than the lower limit, the oil resistance of the resin molded article can be further improved. When the average particle size of calcium carbonate is equal to or smaller than the upper limit, the impact resistance of the resin molded article can be further improved.

[0032] In this specification, the average particle size refers to a volume average particle size calculated from a volume-based distribution by a laser diffraction method using a laser diffraction / scattering type particle size distribution measuring device in accordance with JIS Z 8825:2013.

[0033] When measuring the volume average particle size, for example, calcium carbonate is put into a soap solution (containing 0.01% neutral detergent) so that the concentration is 2% by weight, and ultrasonic waves are irradiated for 1 minute at an output of 300 W using an ultrasonic homogenizer to obtain a suspension. Next, the volume particle size distribution of calcium carbonate is measured for the suspension using a laser diffraction / scattering type particle size distribution measuring device (manufactured by Nikkiso Co., Ltd., product name "Microtrac MT3300"). The cumulative 50% value of this volume particle size distribution can be calculated as the volume average particle size of calcium carbonate.

[0034] In the present invention, the BET specific surface area of ​​calcium carbonate is preferably 5 m 2 / g or more, more preferably 6m 2 / g or more, more preferably 8m 2 / g or more, preferably 20m 2 / g or less, more preferably 15m 2 / g or less, more preferably 11m 2 / g or less.

[0035] When the BET specific surface area of ​​calcium carbonate is equal to or greater than the lower limit, the oil resistance of the resin molded article can be further improved. When the BET specific surface area of ​​calcium carbonate is equal to or less than the upper limit, the impact resistance of the resin molded article can be further improved.

[0036] In this specification, the BET specific surface area can be measured from the nitrogen adsorption isotherm according to the BET method. For example, a measuring device such as Anton Paar's NOVAtouch LX2 can be used.

[0037] In the present invention, the content of calcium carbonate is preferably 1 wt % or more, more preferably 5 wt % or more, and preferably less than 50 wt %, more preferably 40 wt % or less, and even more preferably 30 wt % or less, based on the total amount of the resin molded product.

[0038] When the content of calcium carbonate is equal to or more than the lower limit, the mechanical strength and oil resistance of the resin molded article can be further improved. When the content of calcium carbonate is less than or equal to the upper limit, the impact resistance of the resin molded article can be further improved.

[0039] Each component of the resin molded article will be described in detail below.

[0040] (High density polyethylene resin) In the present invention, the weight average molecular weight of the high-density polyethylene resin is preferably 50,000 or more, more preferably 60,000 or more, even more preferably 70,000 or more, and is 100,000 or less, more preferably 90,000 or less, even more preferably 80,000 or less.

[0041] When the weight average molecular weight of the high-density polyethylene resin is equal to or greater than the lower limit, the impact resistance of the resin molded article can be further improved. When the weight average molecular weight of the high-density polyethylene resin is equal to or less than the upper limit, the dimensional stability of the resin molded article can be further improved.

[0042] In this specification, the weight average molecular weight refers to the weight average molecular weight (Mw) in terms of polystyrene measured by gel permeation chromatography (GPC).

[0043] The MFR of the high-density polyethylene resin is preferably 3 g / 10 min or more, more preferably 5 g / 10 min or more, preferably 20 g / 10 min or less, more preferably 18 g / 10 min or less, even more preferably 15 g / 10 min or less, and particularly preferably 10 g / 10 min or less.

[0044] When the MFR of the high-density polyethylene resin is equal to or higher than the lower limit, the dimensional stability of the resin molded article can be further improved. When the MFR of the high-density polyethylene resin is equal to or lower than the upper limit, the impact resistance of the resin molded article can be further improved.

[0045] In this specification, the MFR can be measured in accordance with JIS K7210.

[0046] The specific gravity of the high density polyethylene resin is preferably 0.94 g / cm 3 More preferably, 0.95 g / cm 3 More preferably, 0.96 g / cm 3 or more, preferably 1 g / cm 3 Less than 0.99 g / cm 3 More preferably, 0.98 g / cm 3 The following is the result.

[0047] When the specific gravity of the high-density polyethylene resin is equal to or higher than the lower limit, the mechanical strength and oil resistance of the resin molded article can be further improved, whereas when the specific gravity of the high-density polyethylene resin is equal to or lower than the upper limit, the weight of the resin molded article can be further reduced.

[0048] The specific gravity of the high-density polyethylene resin can be measured by an underwater displacement method using a high-precision electronic specific gravity meter (manufactured by Toyo Seiki Seisakusho, product name "DSG-1").

[0049] In the present invention, the content of the high-density polyethylene resin is preferably 50% by weight or more, more preferably 60% by weight or more, and even more preferably 70% by weight or more, relative to the total amount of the resin molded body, and is preferably 99% by weight or less, more preferably 95% by weight or less, and even more preferably 90% by weight or less.

[0050] When the content of the high-density polyethylene resin is equal to or more than the lower limit, the oil resistance of the resin molded article can be further improved. When the content of the high-density polyethylene resin is equal to or less than the upper limit, the mechanical strength of the resin molded article can be further improved.

[0051] (Calcium Carbonate) As the calcium carbonate, for example, ground calcium carbonate or synthetic calcium carbonate can be used.

[0052] The shape of calcium carbonate is not particularly limited, and examples thereof include a spherical shape and a spindle shape. Among these, from the viewpoint of further increasing the impact resistance of the resin molded body, the shape of calcium carbonate is preferably a spherical shape.

[0053] In the present invention, the surface of calcium carbonate is preferably treated with a surface treatment agent. Therefore, the surface of calcium carbonate may be covered with a surface treatment layer. The surface treatment layer may cover a part of the surface of calcium carbonate or may cover the entire surface of calcium carbonate.

[0054] The surface treatment agent is not particularly limited, but for example, a surface treatment agent containing a fatty acid can be used. The fatty acid is not particularly limited, but for example, palmitic acid, stearic acid, myristic acid, succinic acid, etc. are listed as saturated fatty acids, and oleic acid, linoleic acid, maleic acid, etc. are listed as unsaturated fatty acids. These fatty acids may be used alone or in combination of two or more kinds.

[0055] In the present invention, the content of calcium carbonate is preferably 1% by weight or more, more preferably 3% by weight or more, and even more preferably 5% by weight or more, relative to the total amount of the resin molded body, and is preferably 50% by weight or less, more preferably 40% by weight or less, and even more preferably 30% by weight or less.

[0056] When the content of calcium carbonate is equal to or more than the lower limit, the mechanical strength and oil resistance of the resin molded article can be further improved. When the content of calcium carbonate is equal to or less than the upper limit, the impact resistance of the resin molded article can be further improved.

[0057] (Calcium stearate) The resin molded product of the present invention may further contain a stearate such as calcium stearate. When the resin molded product contains calcium stearate, the dispersibility and oil resistance of the filler in the resin molded product can be further improved. Examples of stearates other than calcium stearate include aluminum stearate, barium stearate, magnesium stearate, manganese stearate, zinc stearate, and iron stearate. Such other stearates can also be used instead of calcium stearate.

[0058] In the present invention, the content of calcium stearate is preferably 0.01% by weight or more, more preferably 0.02% by weight or more, even more preferably 0.03% by weight or more, and is preferably 1% by weight or less, more preferably 0.5% by weight or less, even more preferably 0.2% by weight or less, based on the total amount of the resin molded product.

[0059] When the content of calcium stearate is equal to or more than the lower limit, the dispersibility of the filler can be improved. When the content of calcium stearate is equal to or less than the upper limit, the oil resistance can be further improved. The resin molded product of the present invention does not need to contain a stearate salt such as calcium stearate.

[0060] (Other resins) The resin molded article of the present invention may contain other resins in addition to the high-density polyethylene resin.

[0061] As the other resin, for example, a known thermoplastic resin can be used. Specific examples of the thermoplastic resin include polyolefin resin other than high density polyethylene resin, polystyrene resin, polyacrylate resin, polymethacrylate resin, polyacrylonitrile resin, polyester resin, polyamide resin, polyurethane resin, polyethersulfone resin, polyetherketone resin, polyimide resin, polydimethylsiloxane resin, polycarbonate resin, or copolymer resin containing at least two of these. These thermoplastic resins may be used alone or in combination.

[0062] The polyolefin resin is not particularly limited, and known polyolefin resins can be used. Specific examples of the polyolefin resin include polyethylene-based resins other than high-density polyethylene resins, such as low-density polyethylene resins, ethylene-α-olefin copolymer resins, ethylene-(meth)acrylic acid copolymer resins, ethylene-(meth)acrylic acid ester copolymer resins, and ethylene-vinyl acetate copolymer resins. The polyolefin resin may be a polypropylene resin, which is a propylene homopolymer, a polypropylene-based resin, such as a propylene-α-olefin copolymer resin, a polybutene resin, which is a butene homopolymer, or a homopolymer or copolymer resin of a conjugated diene, such as butadiene or isoprene. These polyolefin resins may be used alone or in combination. From the viewpoint of further increasing the heat resistance and elastic modulus of the resin molded body, the polyolefin resin is preferably a polypropylene resin.

[0063] In the present invention, the content of the other resin may be, for example, 5% by weight or more and 50% by weight or less based on the total weight of the resin molded product. Also, the content of the other resin may be, for example, 10 parts by weight or more and 100 parts by weight or less based on 100 parts by weight of the high-density polyethylene resin. Note that the resin molded product of the present invention may not contain any other resin than the high-density polyethylene resin.

[0064] (Other inorganic fillers) The resin molded article of the present invention may further contain an inorganic filler other than the calcium carbonate.

[0065] Other inorganic fillers include talc, clay, mica, boron nitride, aluminum nitride, zinc oxide, graphite and other carbon materials. Other inorganic fillers have a BET specific surface area of ​​5 m 2 / g, and the BET specific surface area is 20 m 2 / g or more. The other inorganic filler may be calcium carbonate having an average particle size of less than 0.1 μm, or may be calcium carbonate having an average particle size of more than 5 μm. The other inorganic filler may be used alone or in combination of two or more kinds.

[0066] In the present invention, the content of the other inorganic filler can be, for example, 1% by weight or more and 10% by weight or less based on the total weight of the resin molded product. The resin molded product of the present invention does not necessarily need to contain other inorganic fillers.

[0067] (Other additives) The resin molded product of the present invention may contain various other additives as optional components within a range that does not impair the effects of the present invention. Examples of other additives include antioxidants such as phenols, phosphorus, amines, and sulfurs; ultraviolet absorbers such as benzotriazoles and hydroxyphenyltriazines; metal damage inhibitors; various fillers; antistatic agents; stabilizers; pigments; and the like. These may be used alone or in combination.

[0068] In the present invention, the content of the other additives can be, for example, 0.01% by weight or more and 5% by weight or less based on the total weight of the resin molded product. The resin molded product of the present invention does not necessarily need to contain other additives.

[0069] (Method of manufacturing resin molded body) The resin molded article of the present invention can be obtained by molding a resin composition. The resin composition may contain the components described in the section on the resin molded article above.

[0070] The resin composition can be obtained by melt-kneading the above-mentioned high-density polyethylene resin, calcium carbonate, and, if necessary, calcium stearate, other resins, other inorganic fillers, and other additives.

[0071] The melt-kneading method is not particularly limited, but examples thereof include a method of kneading under heating using a kneading device such as a twin screw kneader such as a plastomill, a single screw extruder, a twin screw extruder, a Banbury mixer, a roll, or a pressure kneader. Among these, the melt-kneading method using an extruder is preferred. The form of the resin composition is not particularly limited, but can be, for example, pellets.

[0072] When pellets are used, the shape is not particularly limited, but examples include a sphere, a cylinder, and a prism. Among these, a cylinder is preferred from the viewpoint of the stability of the pellet shape. In addition, when the pellet size is, for example, a cylinder, the diameter is preferably 0.5 mm or more, more preferably 1 mm or more, and preferably 5 mm or less, more preferably 3 mm or less. The length is preferably 1 mm or more, more preferably 3 mm or more, and preferably 10 mm or less, more preferably 7 mm or less. The size of the pellets can be measured by randomly collecting 100 pellets from a sample and using a vernier caliper.

[0073] The diameter of the pellets of the resin composition other than the cylindrical shape (pellet diameter) is preferably 1 mm or more, more preferably 5 mm or more, and is preferably 15 mm or less, more preferably 10 mm or less. The pellet diameter can be obtained by randomly collecting 100 pellets from a sample and measuring the diameter at the longest point with a vernier caliper.

[0074] The method for molding the resin composition is not particularly limited, and examples thereof include press processing, extrusion processing, extrusion lamination processing, injection molding, etc. Among these, it is preferable to mold the mixture by injection molding.

[0075] [container] FIG. 1 is a schematic perspective view showing a container according to one embodiment of the present invention.

[0076] 1 is a container for storage or transportation. The container 1 is made of the above-mentioned resin molded article of the present invention.

[0077] The container 1 of this embodiment is made of the above-mentioned resin molded article of the present invention, and therefore has excellent oil resistance, mechanical strength, and impact resistance.

[0078] The resin molded article of the present invention is not limited to use as a container for storage or transportation as described above, but may also be used as an oil-resistant container for storing or transporting metal parts or food, or as an oil-resistant part for machinery, etc.

[0079] Examples of items that oil-resistant containers are used to store and transport include metal parts such as bolts and nuts. These parts are heavy because they are made of metal, and oil (mineral oil) is applied to their surfaces for the purposes of rust prevention, improving workability, lubrication, etc.

[0080] Other examples of goods that oil-resistant containers can be used to store or transport include food such as meat, fish, and fried foods, which have fats and oils (animal fats and oils) from meat and fish, and oils (vegetable fats and oils) such as salad oil attached to their surfaces.

[0081] Yet another example of an item that can be stored or transported in an oil-resistant container is oil. Oil can be in liquid or solid form, such as mineral oil, animal oil, or vegetable oil. In addition, rust-preventive oil may contain asphalt, petrolatum, resin, wax, surfactant, fatty acid, fatty acid ester, or the like as components.

[0082] In particular, the resin molded body of the present invention has excellent oil resistance, mechanical strength, and impact resistance, and can therefore be suitably used for applications such as containers for storing and transporting heavy metal mechanical parts.

[0083] The effects of the present invention will be clarified by giving specific examples and comparative examples of the present invention below, but the present invention is not limited to the following examples.

[0084] Example 1 A resin composition was obtained by melt-kneading 85% by weight of high-density polyethylene resin (HDPE resin), 15% by weight of calcium carbonate, and 0.06% by weight of calcium stearate at 180°C using a Labo Plastomill (manufactured by Toyo Seiki Seisakusho, product number "R100"). The resin composition obtained was in the form of pellets, and the pellet diameter was 7 mm. The pellet diameter was determined by randomly sampling 100 pellets from the sample and measuring the diameter at the longest point using a vernier caliper. In addition, as the high-density polyethylene resin, Japan Polyethylene Corporation's product name "HJ560W" (weight average molecular weight: 75,000, specific gravity: 0.964 g / m 3 Calcium carbonate A (synthetic calcium carbonate, manufactured by Shiraishi Kogyo Co., Ltd., product name "Vigot-15", volume average particle size: 0.15 μm, BET specific surface area: 10 m) was used. 2 The calcium stearate used was "SC-100" manufactured by Sakai Chemical Industry Co., Ltd.

[0085] The weight average molecular weight of the high density polyethylene resin was determined by analysis using gel permeation chromatography (GPC, manufactured by Waters Corporation, product number "GPCV2000") and converted into polystyrene equivalent weight average molecular weight (Mw).

[0086] The average particle size of calcium carbonate was calculated by the volume-based distribution by the laser diffraction method using a laser diffraction / scattering particle size distribution analyzer (manufactured by Nikkiso Co., Ltd., product name "Microtrac MT3300") in accordance with JIS Z 8825:2013. The BET specific surface area of ​​calcium carbonate was measured from the nitrogen adsorption isotherm in accordance with the BET method. The measuring device used was Anton Paar's product number "NOVAtouch LX2."

[0087] Next, the obtained resin composition was injection molded to obtain a resin molded article having a shape for each evaluation, where the injection molding was performed under the conditions of a resin temperature of 230° C., a mold temperature of 50° C., and an injection speed of 30 mm / s.

[0088] Example 2 Instead of calcium carbonate A, calcium carbonate B (heavy calcium carbonate, manufactured by Bihoku Funka Kogyo Co., Ltd., product name "u-powder3S", volume average particle size: 1.4 μm, BET specific surface area: 8.5 m 2 The resin molded articles having the shapes for each evaluation were obtained in the same manner as in Example 1, except that a resin composition for forming the resin molded article was used (coated with 1,000g of cellulose acetate, surface-treated with stearic acid).

[0089] (Examples 3 and 4) Resin molded articles having shapes for each evaluation were obtained in the same manner as in Example 2, except that the blending amounts of high-density polyethylene resin, calcium carbonate B, and calcium stearate were changed as shown in Table 1 below.

[0090] Comparative Example 1 Instead of calcium carbonate A, calcium carbonate C (heavy calcium carbonate, manufactured by Bihoku Funka Kogyo Co., Ltd., product name "Softon 2200", volume average particle size: 5.2 μm, BET specific surface area: 3.0 m 2 / g, no surface treatment) was used, and the same procedure as in Example 1 was repeated to obtain resin molded articles having the shapes indicated for each evaluation.

[0091] Comparative Example 2 Resin molded articles having the shapes for each evaluation were obtained in the same manner as in Example 1, except that calcium carbonate and calcium stearate were not used.

[0092] Comparative Example 3 Instead of high density polyethylene resin, polypropylene resin (PP resin, manufactured by Japan Polypropylene Corporation, product name "BC3LS", specific gravity: 0.90 g / m 3 A resin molded article having the shape for each evaluation was obtained in the same manner as in Comparative Example 2, except that a resin having a viscosity of 1000 psig (MFR: 10 g / 10 min) was used.

[0093] [evaluation] (Tensile test) In Examples 1 to 4 and Comparative Examples 1 to 3, dumbbell-shaped resin molded articles having a length of 170 mm, a width of 80 mm, a central width of 10 mm, and a thickness of 4 mm were obtained as samples.

[0094] The tensile strength (strength) and tensile modulus (elasticity) of the obtained sample were measured in accordance with JIS K 7139. The tensile strength and tensile modulus were measured using a Tensilon universal testing machine (manufactured by Orientec Co., Ltd., model number "RTC-1210A").

[0095] (Bending test) In Examples 1 to 4 and Comparative Examples 1 to 3, a rectangular test piece conforming to ISO294-1, a resin molded article having a length of 80 mm, a width of 10 mm and a thickness of 4 mm, was obtained and used as a sample.

[0096] The flexural strength (strength) and flexural modulus (elasticity) of the obtained sample were measured in accordance with ISO 178. The flexural strength was measured using a Tensilon universal testing machine (manufactured by Orientec Co., Ltd., model number "RTC-1210A").

[0097] (Weight change rate) In Examples 1 to 4 and Comparative Examples 1 to 3, resin molded bodies measuring 100 mm in length × 100 mm in width × 2 mm in thickness were obtained and used as samples.

[0098] The sample was immersed for 500 hours in 1 L of oil (manufactured by Nihon Parkerizing Co., Ltd., product name "NOX-RUST 46-78A") at a temperature of 60° C. At this time, the weight change rate ((BA) / A) was calculated from the weight A of the sample before immersion in the oil and the weight B of the sample after immersion in the oil.

[0099] The results are shown in Table 1 below.

[0100] [Table 1]

[0101] (Low temperature test) In Examples 2 to 4 and Comparative Examples 2 and 3, resin molded bodies (containers) having the shape shown in Fig. 1 were obtained as samples. The following empty drop strength and ball drop strength tests were performed after the resin molded bodies were cooled at -30°C for 6 hours.

[0102] Empty drop strength; The sample was placed at a height of 3 m in a room at 23°C. The sample was then allowed to naturally drop so that the corners of the sample touched the ground, and the sample was visually checked for the occurrence of cracks. If no cracks were found in the sample, the sample was allowed to naturally drop again so that the corners of the sample touched the ground, and the sample was visually checked for the occurrence of cracks. The above was repeated three times, and the sample was evaluated according to the following criteria.

[0103] <Evaluation criteria> ○: The grounded portion of the sample was visually inspected and found to have no cracks or breaks. △: When the sample's contact area was visually inspected, any cracks or breaks were found to be minute and less than 2 mm in length. ×: The grounded portion of the sample was visually inspected and found to have cracks or fissures with a length of 2 mm or more.

[0104] Drop ball strength; First, the sample was placed on a horizontal surface in a temperature-controlled room at 23°C. Then, an iron ball (weight 1 kg) was allowed to drop naturally onto the top surface of the sample from a position 1 m high in the vertical direction from the top surface of the sample. The presence or absence of cracks in the sample due to the drop of the iron ball was visually observed. If no cracks were observed in the sample, the iron ball was allowed to drop naturally onto the top surface of the sample from a position 10 cm higher in the vertical direction, and the presence or absence of cracks in the sample was visually observed. Then, the height of the iron ball was increased by 10 cm at a time, and the free fall of the iron ball was repeated until a crack was observed in the sample, and the minimum height of the iron ball at which a crack occurred in the sample was measured.

[0105] The results are shown in Table 2 below.

[0106] [Table 2]

[0107] (Oil immersion test) Tensile test; In Example 2 and Comparative Examples 2 and 3, a dumbbell-shaped plate-like resin molding having a length of 170 mm, a width of 80 mm, a central width of 10 mm, and a thickness of 4 mm was obtained as a sample.

[0108] The samples were immersed in 1 L of oil (manufactured by Nihon Parkerizing Co., Ltd., product name "NOX-RUST 46-78A") at the temperature and time conditions shown in Table 3. At this time, the tensile strength (strength) and tensile elongation (elongation) of the samples before and after oil immersion were measured in accordance with JIS K7139. The tensile strength and tensile elongation were measured using a Tensilon universal testing machine (manufactured by Orientec Co., Ltd., model number "RTC-1210A").

[0109] The results are shown in Table 3 below.

[0110] [Table 3]

[0111] Bottom deflection test; In Example 2 and Comparative Examples 2 and 3, a resin molded product (container) having the shape shown in FIG. 1 was obtained and used as a measurement sample.

[0112] The measurement samples were stacked in two layers, and the depth of the center of the upper sample was measured in length (measured value before the test). Next, 300 ml of oil (manufactured by Nihon Parkerizing Co., Ltd., product name "NOX-RUST 46-78A") and 20 kg of bolts were placed in the upper sample, and it was placed in a thermostatic chamber at 60°C and left for 24 hours. Then, the oil and bolts were removed, and the depth (mm) of the center of the upper sample was measured with a ruler. Next, after leaving it in a room at 23°C for 24 hours, the depth of the center of the upper sample was measured with a ruler. The above operation was repeated to evaluate the change in the depth of the center of the upper sample (change in the amount of deflection of the bottom of the container).

[0113] The results are shown in Table 4 below.

[0114] [Table 4]

[0115] As shown in Tables 1 to 4, it was confirmed that the resin molded articles obtained in Examples 1 to 4 were excellent in oil resistance, mechanical strength, and impact resistance. Although the results of Example 1 are not shown in Table 2, it was confirmed that the impact resistance was enhanced as in Example 2. On the other hand, the resin molded articles obtained in Comparative Examples 1 to 3 did not have sufficient oil resistance, and this tendency was particularly noticeable in Comparative Example 3, which used polypropylene resin. Moreover, Comparative Example 2, which used only high-density polyethylene resin, did not have sufficient mechanical strength. [Explanation of symbols]

[0116] 1. Container

Claims

1. A resin molded body comprising a high-density polyethylene resin and calcium carbonate, The resin molded body is cut into a size of 100 mm length × 100 mm width × 2 mm thickness to prepare a sample, and the sample is immersed in 1 L of oil at a temperature of 60°C for 500 hours. A weight change rate ((B-A) / A) calculated from a weight A of the sample before immersion in the oil and a weight B of the sample after immersion in the oil is 1% or more and 10% or less.

2. 2. The resin molded article according to claim 1, wherein the calcium carbonate has a volume average particle size of 0.1 μm or more and 5 μm or less.

3. 3. The resin molded article according to claim 1, wherein the content of the calcium carbonate is 1% by weight or more and less than 50% by weight based on the total weight of the resin molded article.

4. The BET specific surface area of ​​the calcium carbonate is 5 m ２ / g or more, 20m ２ The resin molded article according to claim 1 or 2, wherein the viscosity is 100 / g or less.

5. 3. The resin molded article according to claim 1, wherein the high-density polyethylene resin has a weight average molecular weight of 50,000 or more and 100,000 or less.

6. 3. The resin molded article according to claim 1, wherein the surface of the calcium carbonate is treated with a surface treatment agent containing a fatty acid.

7. 7. The resin molded article according to claim 6, wherein the fatty acid is at least one selected from the group consisting of palmitic acid, stearic acid, myristic acid, succinic acid, oleic acid, linoleic acid, and maleic acid.

8. The resin molded article according to claim 1 or 2, further comprising calcium stearate.

9. 9. The resin molded article according to claim 8, wherein the content of the calcium stearate is 0.01% by weight or more and 1% by weight or less based on the total amount of the resin molded article.

10. A container comprising the resin molded article according to claim 1 or 2.

Images