Resin molded body and method for producing the same

Abstract

To provide a resin molding excellent in dielectric characteristics and moldability and a production method of a resin molding.SOLUTION: A resin molding is made of a resin composition for a molding having 10-70 pts.mass of a polypropylene-based resin to 100 pts.mass of a vinyl chloride-based resin. The resin molding has an average size of a granular lump of the propylene-based resin of 1-25 μm per 1 cm2-unit area in the resin molding.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a resin molded product and a method for producing the resin molded product, and more particularly to a resin molded product used as a wire coating material for insulated wires used in automotive wire harnesses, electronic devices, etc., and a method for producing the resin molded product. [Background technology]

[0002] In recent years, the signal bands of information and communication devices and the CPU clock times of computers have become increasingly high-frequency, reaching the gigahertz (GHz) range, and it is known that the higher the frequency of the signals used, the greater the dielectric loss.Since the increase in dielectric loss attenuates the electrical signal and impairs the reliability of the signal, it is necessary to select a material with excellent dielectric properties for the insulator in order to suppress the dielectric loss. For example, in automobiles, the on-board information and communication devices are becoming increasingly electronic, and in order to suppress dielectric loss in the information and communication devices, it is necessary to select materials with excellent dielectric properties for the coating materials used to coat the electric wires used in the information and communication devices.

[0003] In addition, with the progress of electronicization of information and communication devices, the number of electric and electronic wiring circuits in the information and communication devices has increased significantly, forming a complex wiring circuit structure. For the covering material for covering the electric wires used in the complex wiring circuit structure, it is necessary to select a material that is soft and has excellent formability so that it can follow the complex wiring circuit structure. Therefore, flexible polyvinyl chloride is sometimes used as a material with excellent dielectric properties and formability. In order to reduce the dielectric properties of flexible polyvinyl chloride, it has been proposed to use it by foaming (see, for example, Patent Document 1). However, the plasticizer contained in flexible polyvinyl chloride tends to bleed out with long-term use. In addition, the dielectric properties tend to deteriorate due to the influence of the bleed-out plasticizer. In order to prevent the deterioration of the dielectric properties of soft vinyl chloride, a vinyl chloride resin containing a polyolefin resin is sometimes used (see, for example, Patent Document 2). However, such mixed resins are difficult to mold due to the difference in molding temperature between the mixed resins. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-9117 A [Patent Document 2] JP 2020-198240 A Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the above circumstances, an object of the present invention is to provide a resin molded article having excellent dielectric properties and moldability, and a method for producing the resin molded article. [Means for solving the problem]

[0006] As a result of intensive research by the inventors in order to achieve the above object, it was found that it is possible to obtain a resin molded article having excellent dielectric properties and moldability by molding a mixed resin of a vinyl chloride resin and a polypropylene resin while maintaining the granular shape of the polypropylene resin. Based on this finding, the inventors further researched and completed the present invention.

[0007] The present invention has been made to solve the above problems, and the gist of the present invention is as follows. [1] A resin molding comprising a resin composition for molding containing 10 to 70 parts by mass of polypropylene resin per 100 parts by mass of vinyl chloride resin, 2 The resin molded product has an average size of the polypropylene resin granules per unit area of ​​1 to 25 μm. [2] The resin molded product according to [1], wherein the vinyl chloride resin has a softening point (Ta) of 50 to 80°C. [3] The resin molded body according to [1] or [2], wherein the vinyl chloride resin is a vinyl chloride copolymer. [4] The resin molded product according to any one of [1] to [3], wherein the polypropylene resin has a softening point (Tb) of 110 to 150°C. [5] The resin molded body according to any one of [1] to [4], wherein the difference (Tb-Ta) between the softening point (Tb) of the polypropylene resin and the softening point (Ta) of the vinyl chloride resin is 60 to 100°C. [6] The resin molded article according to any one of [1] to [5], which is a wire coating material. [7] A method for producing a resin molded product, comprising: a preparation step of preparing a resin composition for molded products having 10 to 70 parts by mass of a polypropylene resin per 100 parts by mass of a vinyl chloride resin; and a molding step of molding the resin composition for molded products at a molding temperature that is equal to or higher than the softening point (Ta) of the vinyl chloride resin and equal to or lower than the softening point (Tb) of the polypropylene resin. [8] The method for producing a resin molded product according to [7], wherein the molding temperature is 70 to 150°C. Effect of the Invention

[0008] According to the present invention, it is possible to provide a resin molded article having excellent dielectric properties and moldability, and a method for producing the resin molded article. [Brief description of the drawings]

[0009] [Figure 1] 2 is a TEM image of a resin molded body according to Example 1. [Diagram 2] 1 is a TEM image of a resin molded body according to Comparative Example 3. [Diagram 3] 2 is an image of the resin molded body according to Example 1 taken by a laser microscope. [Figure 4] 13 is a laser microscope image of a resin molded body according to Comparative Example 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] [Resin molding] The resin molded body according to the embodiment of the present invention is made of a resin composition for molding having 10 to 70 parts by mass of polypropylene resin relative to 100 parts by mass of vinyl chloride resin. If the blending ratio of polypropylene resin in the resin composition for molding forming the resin molded body is less than 10 parts by mass relative to 100 parts by mass of vinyl chloride resin, the dielectric constant after molding cannot be sufficiently reduced, and a molded body having excellent dielectric properties cannot be obtained. If the blending ratio of polypropylene resin in the resin composition for molding forming the resin molded body is more than 70 parts by mass relative to 100 parts by mass of vinyl chloride resin, molding at or below the softening point of the polypropylene resin becomes difficult. From the above viewpoints, the blending ratio of the polypropylene-based resin in the resin composition for molded bodies is preferably 20 to 60 parts by mass, more preferably 25 to 55 parts by mass, and even more preferably 30 to 50 parts by mass, per 100 parts by mass of the vinyl chloride-based resin.

[0011] The resin molded article according to the embodiment of the present invention has a diameter of 1 cm 2 The average size of the polypropylene resin granules per unit area is 1 to 25 μm. 2 If the average size of the polypropylene resin granules per unit area is less than 1 μm, the polypropylene resin granules will be poorly dispersed, and the granules will aggregate, resulting in poor moldability. 2 If the average size of the polypropylene resin granular agglomerates per unit area exceeds 25 μm, it becomes difficult to obtain good molding when using the resin composition for molding. From the above viewpoint, 1 cm 2 The average size of the polypropylene resin granular agglomerates per unit area is preferably 1 to 25 μm, more preferably 1 to 20 μm, and even more preferably 1 to 15 μm. <Method for measuring the average size of granular mass> 1cm from any point on the cross section of the resin molded product 2Three locations are selected, and the maximum diameter of each granular mass within the range is measured using a transmission electron microscope (TEM). The maximum diameter of each granular mass of polypropylene resin present at each location is measured, and the average of the measured maximum diameters is calculated. 2 The average size of the polypropylene resin granules per unit area is used. In this case, the maximum diameter is not measured for photographs of only a portion of the polypropylene resin granules.

[0012] INDUSTRIAL APPLICABILITY The resin molded article according to the embodiment of the present invention has excellent dielectric properties and moldability, and therefore can be suitably used as a wire coating material for insulated wires used in wire harnesses for automobiles, electronic devices, and the like.

[0013] <Vinyl chloride resin> The vinyl chloride resin is not particularly limited, and examples thereof include homopolymers of vinyl chloride monomers, (1) copolymers of vinyl chloride monomers and polymerizable monomers other than vinyl chloride monomers, and (2) graft copolymers in which vinyl chloride monomers or vinyl chloride resins are grafted onto polymers other than vinyl chloride resins. Further examples include chlorinated vinyl chloride resins in which these vinyl chloride resins are chlorinated. These vinyl chloride resins may be used alone or in combination of two or more.

[0014] (1) The polymerizable monomer in the copolymer of vinyl chloride monomer and a polymerizable monomer other than vinyl chloride monomer is not particularly limited, and examples thereof include α-olefins having 2 to 16 carbon atoms (e.g., ethylene, propylene, and butylene); vinyl esters of aliphatic carboxylic acids having 2 to 16 carbon atoms (e.g., vinyl acetate and vinyl propionate); alkyl vinyl ethers having 2 to 16 carbon atoms (e.g., butyl vinyl ether and cetyl vinyl ether); alkyl (meth)acrylates having 1 to 16 carbon atoms (e.g., methyl (meth)acrylate, ethyl (meth)acrylate, and butyl acrylate); aryl (meth)acrylates (e.g., phenyl methacrylate); aromatic vinyls (e.g., styrene and α-substituted styrenes (e.g., α-methylstyrene)); vinyl halides (e.g., vinylidene chloride and vinylidene fluoride); and N-substituted maleimides (N-phenylmaleimide and N-cyclohexylmaleimide).

[0015] (2) Polymers that give graft copolymers together with vinyl chloride monomers or vinyl chloride resins include any polymers that can be graft-polymerized with vinyl chloride monomers, regardless of whether they are homopolymers or copolymers. Examples include copolymers of α-olefins and vinyl esters (e.g., ethylene-vinyl acetate copolymers); copolymers of α-olefins, vinyl esters, and carbon monoxide (e.g., ethylene-vinyl acetate-carbon monoxide copolymers); copolymers of α-olefins and alkyl (meth)acrylates (e.g., ethylene-methyl methacrylate copolymers and ethylene-ethyl acrylate copolymers); copolymers of α-olefins, alkyl (meth)acrylates, and carbon monoxide (e.g., ethylene-butyl acrylate-carbon monoxide copolymers); copolymers of two or more different α-olefins (e.g., ethylene-propylene copolymers); copolymers of unsaturated nitriles and dienes (e.g., acrylonitrile-butadiene copolymers); polyurethanes; and chlorinated polyolefins (e.g., chlorinated polyethylene and chlorinated polypropylene).

[0016] The average polymerization degree of the vinyl chloride resin is not particularly limited, but a smaller average polymerization degree leads to a decrease in the physical properties of the resin molded product, while a larger average polymerization degree leads to an increase in melt viscosity, making molding difficult. Therefore, the average polymerization degree is preferably 400 to 1,600, more preferably 500 to 1,500, and even more preferably 600 to 1,400. The above-mentioned average degree of polymerization means an average degree of polymerization measured in accordance with JIS K 6720-2:1999 "Plastics-Vinyl chloride homopolymer and copolymer (PVC)-Part 2: Preparation of test pieces and determination of properties" using a resin obtained by dissolving a vinyl chloride resin in tetrahydrofuran (THF), removing insoluble components by filtration, and then drying and removing the THF in the filtrate.

[0017] The polymerization method for the vinyl chloride resin is not particularly limited, and any conventionally known polymerization method can be used, such as bulk polymerization, solution polymerization, emulsion polymerization, and suspension polymerization.

[0018] The method for chlorinating the vinyl chloride resin is not particularly limited, and any conventionally known chlorination method can be used, such as a thermal chlorination method or a photochlorination method.

[0019] The softening point (Ta) of the vinyl chloride resin used in the present invention is preferably 50 to 80° C., more preferably 53 to 75° C., and even more preferably 55 to 70° C. When the softening point of the vinyl chloride resin is within this range, even when the resin is molded at a temperature equal to or lower than the softening point (Tb) of the polypropylene resin shown below, the resin can be sufficiently gelled, resulting in good moldability. In the present invention, the term "softening point" refers to the temperature at which a substance such as a resin softens and begins to deform due to an increase in temperature. Usually, the temperature at which a substance becomes completely liquid when the temperature of the substance is increased is called the melting point. However, substances such as resins do not show a clear melting point, but gradually soften and reach a molten state, and it is difficult to identify a clear change in state, so they are sometimes called softening points to distinguish them from melting points. The softening point referred to here can be expressed by the Vicat softening temperature measured in accordance with Method A of JIS K7206:2016 "Plastics - Thermoplastics - How to determine Vicat softening temperature (VST)".

[0020] <Polypropylene resin> The polypropylene resin is not particularly limited, and examples thereof include homopolypropylene, ethylene-propylene random copolymers mainly composed of propylene, and ethylene-propylene block copolymers mainly composed of propylene. These polypropylene resins may be used alone or in combination of two or more. Among them, it is preferable to contain an ethylene-propylene random copolymer mainly composed of propylene. From the viewpoint of reducing the dielectric constant, an ethylene-propylene block copolymer mainly composed of propylene may be contained. Incidentally, "mainly composed" here means that the propylene content in the copolymer is 50% by mass or more.

[0021] The softening point (Tb) of the polypropylene resin used in the present invention is preferably 110 to 150° C., more preferably 115 to 148° C., and even more preferably 120 to 145° C. When the softening point (Tb) of the polypropylene resin is within this range, when a resin composition for molding obtained by mixing the polypropylene resin with the vinyl chloride resin is used to mold a resin molding, the molding temperature can be set lower than the softening point (Tb) of the polypropylene resin, thereby making it possible to improve moldability. The softening point can be expressed by the Vicat softening temperature measured in accordance with Method A of JIS K7206:2016 "Plastics - Thermoplastics - Determination of Vicat softening temperature (VST)".

[0022] The difference (Tb-Ta) between the softening point (Tb) of the polypropylene resin used in the present invention and the softening point (Ta) of the vinyl chloride resin is preferably 60 to 100° C., more preferably 65 to 95° C., and even more preferably 70 to 90° C. When the difference (Tb-Ta) between the softening point (Tb) of the polypropylene resin and the softening point (Ta) of the vinyl chloride resin is within the above range, the temperature setting during molding becomes easy when a resin molding is formed using the resin composition for molding, and the moldability becomes good.

[0023] (Additives) In addition, additives may be added to the resin molded product of the present invention within the scope of not impairing the object of the present invention. Examples of various additives that may be added to the resin molded product include heat stabilizers, lubricants, processing aids, impact modifiers, heat resistance improvers, antioxidants, ultraviolet absorbers, antistatic agents, light stabilizers, pigments, flame retardants, inorganic fillers, and plasticizers. Only one type of additive may be used, or two or more types may be used in combination.

[0024] The heat stabilizer is not particularly limited, and examples thereof include a heat stabilizer and a heat stabilization assistant, etc. The heat stabilizer is not particularly limited, and examples thereof include an organotin-based stabilizer, a lead-based stabilizer, a calcium-zinc-based stabilizer, a barium-zinc-based stabilizer, and a barium-cadmium-based stabilizer, etc. Examples of the organic tin stabilizer include dibutyltin mercapto, dioctyltin mercapto, dimethyltin mercapto, dibutyltin mercapto, dibutyltin maleate, dibutyltin maleate polymer, dioctyltin maleate, dioctyltin maleate polymer, dibutyltin laurate, and dibutyltin laurate polymer, etc. The above stabilizers may be used alone or in combination of two or more. The heat stabilization assistant is not particularly limited, and examples thereof include epoxidized soybean oil, phosphoric acid ester, polyol, hydrotalcite, zeolite, etc. The heat stabilization assistant may be used alone or in combination of two or more kinds.

[0025] The lubricant may be an internal lubricant or an external lubricant. The internal lubricant is used to reduce the flow viscosity of the molten resin during molding and to prevent heat generation due to friction. The internal lubricant is not particularly limited, and examples thereof include butyl stearate, lauryl alcohol, stearyl alcohol, epoxy soybean oil, glycerin monostearate, stearic acid, bisamide, etc. The above lubricants may be used alone or in combination of two or more kinds. The external lubricant is used for the purpose of increasing the sliding effect between the molten resin and the metal surface during molding. The external lubricant is not particularly limited, and examples thereof include wax-based lubricants such as paraffin wax, polyolefin wax, ester wax, and montanic acid wax. The above lubricants may be used alone or in combination of two or more.

[0026] The processing aid can be a wide variety of known ones and is not particularly limited. Examples of the processing aid include acrylic processing aids such as alkyl acrylate-alkyl methacrylate copolymers having a weight average molecular weight of 100,000 to 2,000,000. The acrylic processing aid is not particularly limited, and examples thereof include n-butyl acrylate-methyl methacrylate copolymers, 2-ethylhexyl acrylate-methyl methacrylate-butyl methacrylate copolymers, etc. These may be used alone or in combination of two or more kinds.

[0027] The impact modifier may be any of a wide variety of known ones, and is not particularly limited. For example, the impact modifier may be one or more selected from the group consisting of methyl methacrylate-butadiene-styrene copolymer (MBS), chlorinated polyethylene, acrylic rubber, and the like.

[0028] The heat resistance improver can be a wide variety of known ones and is not particularly limited. For example, α-methylstyrene-based, N-phenylmaleimide-based resins, etc. can be used as the heat resistance improver.

[0029] The antioxidant is not particularly limited, and a wide variety of known antioxidants can be used. Examples of the antioxidant include phenol-based antioxidants.

[0030] The ultraviolet absorbing agent is not particularly limited, and a wide variety of known ultraviolet absorbing agents can be used. Examples of ultraviolet absorbing agents include salicylic acid ester-based, benzophenone-based, benzotriazole-based, and cyanoacrylate-based ultraviolet absorbing agents. These may be used alone or in combination of two or more.

[0031] The antistatic agent is not particularly limited, and a conventionally known antistatic agent can be used, and an anionic surfactant, a cationic surfactant, a nonionic surfactant, an amphoteric surfactant, etc. can be used. Examples of the anionic surfactant include fatty acid salts, higher alcohol sulfate salts, liquid fatty oil sulfate salts, fatty amines, sulfate salts of amides, sulfonic acid salts of dibasic fatty acid esters, fatty acid amide sulfonates, alkylaryl sulfonates, formalin condensed naphthalene sulfonates, and mixtures thereof. Examples of the cationic surfactant include fatty amine salts, quaternary ammonium salts, alkylpyridinium salts, and mixtures thereof. Examples of the nonionic surfactant include polyoxyethylene alkyl ethers, polyoxyethylene alkylphenol esters, polyoxyethylene alkyl esters, sorbitan alkyl esters, polyoxyethylene sorbitan alkyl esters, and mixtures thereof. A mixture of a nonionic surfactant and an anionic surfactant or a cationic surfactant may also be used. Examples of amphoteric surfactants include imidazoline type, higher alkylamino type (betaine type), sulfate ester, phosphate ester type, sulfonic acid type, etc. The antistatic agent may be used alone or in combination of two or more types.

[0032] The light stabilizer is not particularly limited, and a wide variety of known light stabilizers can be used. Examples of the light stabilizer include hindered amine light stabilizers.

[0033] The pigment is not particularly limited, and a wide variety of known pigments can be used. Examples of pigments include organic pigments such as azo, phthalocyanine, threne, and dye lake pigments; and inorganic pigments such as oxide, molybdenum chromate, sulfide / selenide, and ferrocyanide pigments. These pigments may be used alone or in combination of two or more.

[0034] The flame retardant is not particularly limited, and a wide variety of known flame retardants can be used. Examples of the flame retardant include red phosphorus, phosphoric acid ester, phosphate-containing flame retardant, bromine-containing flame retardant, boric acid-containing flame retardant, antimony-containing flame retardant, and metal hydroxide. These may be used alone or in combination of two or more.

[0035] The inorganic filler is not particularly limited, and examples thereof include inorganic fillers such as carbonates such as talc, heavy calcium carbonate, precipitated calcium carbonate, and colloidal calcium carbonate, aluminum hydroxide, magnesium hydroxide, titanium oxide, clay, mica, wollastonite, zeolite, silica, zinc oxide, magnesium oxide, carbon black, graphite, glass beads, glass fibers, carbon fibers, and metal fibers, as well as polyamides, etc. The above fillers may be used alone or in combination of two or more.

[0036] The plasticizer is not particularly limited, and a wide variety of known plasticizers can be used. For example, one or more plasticizers selected from the group consisting of dibutyl phthalate, di-2-ethylhexyl phthalate, and di-2-ethylhexyl adipate can be used.

[0037] [Method of manufacturing resin molded body] The method for producing a resin molded body in the present invention includes a preparation step of preparing a resin composition for molding having 10 to 70 parts by mass of polypropylene resin per 100 parts by mass of vinyl chloride resin, and a molding step of molding the resin composition for molding at a temperature not lower than the softening point (Ta) of the vinyl chloride resin and not higher than the softening point (Tb) of the polypropylene resin.

[0038] In the preparation step, the vinyl chloride resin, the polypropylene resin, and the optional components can be mixed using known devices such as a bead mill, a Banbury mixer, a kneader mixer, a kneading roll, a Raikai mixer, and a planetary mixer to obtain a resin composition for molding. When the resin composition for molding that forms the resin molding of the present invention is diluted with a solvent, the diluted solution of the resin composition for molding may be obtained by further adding a solvent to these and mixing them using the above-mentioned mixing device.

[0039] In the molding process, the resin composition for molded bodies is heated to a temperature equal to or higher than the softening point (Ta) of the vinyl chloride resin and equal to or lower than the softening point (Tb) of the polypropylene resin by a molding method such as extrusion molding, injection molding, or press molding, and molded to obtain a resin molded body. The molding method is preferably extrusion molding, and molding can be performed using a single screw extruder, a twin screw extruder, an injection molding machine, or the like. The resin molded product obtained by the method for producing a resin molded product of the present invention can be used as a wire covering material having a desired thickness by rolling it with a rolling machine or the like.

[0040] If the molding temperature in the molding step is lower than the softening point (Ta) of the vinyl chloride resin, the vinyl chloride resin will be too gelled or too insufficient during molding, resulting in poor moldability. If the molding temperature in the molding step exceeds the softening point (Tb) of the polypropylene resin, the polypropylene resin will melt entirely and will not remain in the resin molded body as granular lumps, making it difficult to maintain the dielectric constant of the polypropylene resin. From the above viewpoints, the molding temperature in the molding step is preferably 70 to 150°C, more preferably 75 to 145°C, and even more preferably 80 to 140°C.

[0041] According to the method for producing a resin molded body of the present invention, a resin molded body can be produced from a resin composition for moldings having 10 to 70 parts by mass of polypropylene-based resin per 100 parts by mass of vinyl chloride-based resin, thereby making it possible to obtain a resin molded body having excellent dielectric properties and moldability. Furthermore, according to the method for producing a resin molded product of the present invention, by heating and molding the resin composition for molding to a temperature equal to or lower than the softening point (Tb) of the polypropylene resin, the polypropylene resin does not melt entirely and remains in the resin molded product as granular lumps, so that it is possible to maintain the dielectric constant of the polypropylene resin. Also, according to the method for producing a resin molded product of the present invention, by heating and molding the resin composition for molding to a temperature equal to or higher than the softening point (Ta) of the vinyl chloride resin, it is possible to eliminate problems such as excess or deficiency of gel of the vinyl chloride resin during molding.

[0042] Although the embodiment of the present invention has been described above, the present invention is not limited to these examples, and it is needless to say that the present invention can be embodied in various forms without departing from the gist of the present invention. EXAMPLES

[0043] Hereinafter, the embodiments of the present invention will be described more specifically based on examples, but the present invention is not limited to these.

[0044] <Preparation of resin molded body> [Example 1, Comparative Examples 1 and 3] 100 parts by mass of vinyl chloride resin (Tokuyama Sekisui Co., Ltd., product number SL-P40) was mixed with 2 parts by mass of organotin stabilizer (Nitto Kasei Co., Ltd., product number ONZ-7F), 0.5 parts by mass of wax lubricant (Clariant Japan Co., Ltd., product number Wax OP), and further with polypropylene resin (Seishin Co., Ltd., product number PPW-5J) in the ratio shown in Table 1, and then stirred and mixed in a Henschel mixer (Kawata Co., Ltd.) with an internal volume of 200 liters to obtain a resin composition for molding. The obtained resin composition for molding was kneaded with rolls heated to the temperature shown in Table 1, and a molded product was produced with a press machine heated to 100°C to obtain a resin molding.

[0045] [Examples 2 to 3, Comparative Examples 2 and 4] 100 parts by mass of vinyl chloride resin (Tokuyama Sekisui Co., Ltd., product number TG40) was mixed with 2 parts by mass of organotin stabilizer (Nitto Kasei Co., Ltd., product number ONZ-7F), 0.5 parts by mass of wax lubricant (Clariant Japan Co., Ltd., product number Wax OP), and polypropylene resin (Seishin Co., Ltd., product number PPW-5J) in the ratio shown in Table 1, and then stirred and mixed in a Henschel mixer (Kawata Co., Ltd.) with an internal volume of 200 liters to obtain a resin composition for molding. The obtained resin composition for molding was kneaded with a roll heated to the temperature shown in Table 1, and a molded product was produced with a press machine heated to 100°C to obtain a resin molding.

[0046] <Softening point (Vicat softening temperature) measurement> The softening points of the vinyl chloride resin and polypropylene resin used were measured in accordance with Method A of JIS K7206:2016 "Plastics - Thermoplastics - Determination of Vicat Softening Temperature (VST)". Specifically, the resin was dried at 100°C for 3 hours and then hot pressed at melting point (Tm) + 30°C to prepare a test piece of 10mm x 10mm x 5mm thick. The test piece was measured three times under the conditions of a heating rate of 50°C / hour and a test load of 10N, and the average value of these was taken as the Vicat softening temperature. The softening points (Ta) of the vinyl chloride resin, the softening point (Tb) of the polypropylene resin, and the difference (Tb-Ta) are shown in Table 1.

[0047] <Dielectric property evaluation> The dielectric constant of the obtained resin molded body was measured in accordance with IEC62631-2-1 "Automatic Balancing Bridge Method". The measurement equipment used was a Precision LCR Meter E4980A (manufactured by Agilent Technologies, Inc.), which was set between parallel electrodes of conductive silver paint with a diameter of 36 mm, and the dielectric constant was obtained under conditions of room temperature (23°C) and a frequency of 1 MHz. The obtained dielectric constant was judged according to the following criteria. "Judgment criteria" A (pass): Dielectric constant is 3.1 (F / m) or less B (Fail): Dielectric constant is over 3.1 (F / m)

[0048] <Moldability evaluation> When kneaded in a heated open roll mixer, the resin molded sheet was wrapped around the front roll within 5 minutes, and the appearance of the resin molded sheet was observed 3 minutes later and rated according to the following criteria. "Judgment criteria" A (Pass): The appearance is smooth and the sheet has no sagging. B (Failed): The resin is molten and cannot be molded into a sheet, but the kneaded pieces can be collected and pressed to create a molded product. C (fail): Sheet molding is not possible due to melting of resin

[0049] <Check for granular lumps> From the manufactured resin molded body, 1 cm from any three points 2 A piece of the polypropylene resin was cut out as a sample for TEM, and the maximum diameter of the polypropylene resin granules in the sample was measured by TEM. The average of the maximum diameters was calculated, and the maximum diameter of the granules in the resin molded body was calculated. 2 The average size of the polypropylene resin granules per unit area was obtained, and the results are shown in Table 1.

[0050] [Table 1] *Because it was difficult to measure the average size of the granular masses using a TEM, we measured it using a laser microscope (see Figure 4).

[0051] <Experimental Results> As shown in Examples 1 to 3, in order to obtain a resin molded product with excellent dielectric properties and moldability, it is necessary to mix 100 parts by mass of vinyl chloride resin with 10 to 70 parts by mass of polypropylene resin and mold the product at a temperature below the softening point of the polypropylene resin. As shown in Comparative Example 1, when no polypropylene resin is added, molding at or below the softening point of the polypropylene resin passes, but the dielectric constant becomes too high and the product fails. As shown in Comparative Example 2, when the blending amount of polypropylene-based resin is large, even if the molding temperature is below the softening point of the polypropylene-based resin, the sheet cannot be formed because it does not wind around the front roll, and the moldability is unacceptable. As shown in Comparative Examples 3 and 4, even if the amount of polypropylene-based resin was within the range of 10 to 70 parts by mass, the molding temperature exceeded the softening point of the polypropylene-based resin, so the sheet did not wrap around the front roll, making it impossible to mold into a sheet, and the moldability was unacceptable. As examples, a TEM image of the resin molded body in Example 1 is shown in Fig. 1, and a TEM image of the resin molded body in Comparative Example 3 is shown in Fig. 2. Furthermore, as an overall distribution map of the polyolefin-based resin, a laser microscope image of the resin molded body in Example 1 is shown in Fig. 3, and a laser microscope image of the resin molded body 3 in Comparative Example is shown in Fig. 4. As shown in Figs. 1 to 4, the average size of the granular agglomerates can be set to 1 to 25 µm by setting the molding temperature to be equal to or lower than the softening point of the polypropylene-based resin.

Claims

1. A resin molding comprising a resin composition for molding having 100 parts by mass of a vinyl chloride resin and 10 to 70 parts by mass of a polypropylene resin, 1 cm ２ The average size of the granular agglomerates of the polypropylene-based resin per unit area is 1 to 25 μm, The resin molded product has a difference (Tb-Ta) between the softening point (Tb) of the polypropylene resin and the softening point (Ta) of the vinyl chloride resin of 60 to 100°C.

2. 2. The resin molded article according to claim 1, wherein the vinyl chloride resin has a softening point (Ta) of 50 to 80°C.

3. 3. The resin molded article according to claim 1, wherein the vinyl chloride resin is a vinyl chloride copolymer.

4. The resin molded body according to any one of claims 1 to 3, wherein the polypropylene resin has a softening point (Tb) of 110 to 150°C.

5. The resin molded article according to any one of claims 1 to 4, which is an electric wire coating material.

6. a preparation step of preparing a resin composition for molding having 10 to 70 parts by mass of a polypropylene resin relative to 100 parts by mass of a vinyl chloride resin; and a molding step of molding the resin composition for molding at a molding temperature that is equal to or higher than the softening point (Ta) of the vinyl chloride resin and equal to or lower than the softening point (Tb) of the polypropylene resin, a difference (Tb-Ta) between the softening point (Tb) of the polypropylene resin and the softening point (Ta) of the vinyl chloride resin is 60 to 100°C.

7. The method for producing a resin molded article according to claim 6, wherein the molding temperature is 70 to 150°C.

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