Pellet for three-dimensional modeling

Abstract

This pellet for three-dimensional modeling contains a crosslinked body of a composition containing 100 parts by mass of an olefin-based copolymer rubber, 55-150 parts by mass of a crystalline propylene resin, and 50-150 parts by mass of a softener.

Description

Pellets for 3D modeling

[0001] The present disclosure relates to pellets for three-dimensional fabrication.

[0002] Fused deposition modeling, which involves extruding and layering resin melted by heat, has traditionally been a well-known modeling method for 3D printers. Fused deposition modeling 3D printers are relatively inexpensive and are therefore used in a variety of fields. Fused deposition modeling generally uses a filament method, in which resin molded into a filament shape is introduced. However, in recent years, the adoption of a pellet method, in which resin molded into pellets is introduced, has also been considered. The pellet method allows for easy prototyping, as it allows for the type and amount of color, filler, additives, etc. to be changed. Furthermore, compared to the filament method, the nozzle diameter can be widened, allowing for the rapid production of even large industrial objects.

[0003] For example, Patent Document 1 describes an unvulcanized rubber composition for a three-dimensional modeling printer, which contains a rubber base material, zinc oxide, calcium oxide, a vulcanization accelerator, stearic acid, and carbon black.

[0004] Patent Document 2 describes a granular material for a hot melt type three-dimensional printer, which is made of a thermoplastic elastomer having a Shore A hardness of 0 to 10 and a melt flow rate of 10 to 200 g / 10 min at at least one measurement temperature of 120 to 230°C.

[0005] Patent Document 3 describes a resin composition for three-dimensional modeling, which contains a continuous phase containing a thermoplastic resin and a dispersed phase containing a thermoplastic elastomer dispersed in the continuous phase, and contains resin particles in which the amount of the thermoplastic elastomer is 1 to 12 parts by mass per 100 parts by mass of the total amount of the thermoplastic resin and the thermoplastic elastomer.

[0006] Patent Document 4 describes a filament for 3D printer modeling, characterized by comprising an olefin-based thermoplastic elastomer composition containing 20 to 90 parts by weight of a polypropylene resin (A) having a melt mass-flow rate (MFR; compliant with JIS K7210-1 (2014), 230°C, 2.16 kg load) of 0.1 to 30 g / 10 min, 10 to 80 parts by weight of an olefin-based copolymer rubber (B) (where the total amount of components (A) and (B) is 100 parts by weight), and 20 to 150 parts by weight of a softener (C).

[0007] Patent Document 1: Japanese Patent No. 7193795 Patent Document 2: Japanese Patent No. 7205826 Patent Document 3: International Publication No. 2019 / 146474 Patent Document 4: Japanese Patent Laid-Open No. 2018-144308

[0008] Conventionally, when producing a model using a 3D printer, excellent shape retention has been required.

[0009] An object of one embodiment of the present disclosure is to provide a pellet for three-dimensional printing that can be used to form a three-dimensional object with excellent shape retention.

[0010] The present disclosure includes the following aspects: <1> Pellets for three-dimensional modeling, containing a crosslinked body of a composition including 100 parts by mass of an olefin copolymer rubber, 55 to 150 parts by mass of a crystalline propylene resin, and 50 to 150 parts by mass of a softener. <2> A pellet having a storage modulus of 3.0 x 10 at 140°C. ４ MPa to 8.0 x 10 ４<1> The pellets for 3D printing according to <1>, wherein the tensile strength of the pellets is 100 MPa or less and the pellets have no crossover temperature. <3> The pellets for 3D printing according to <1> or <2>, wherein the propylene-based block copolymer is a block copolymer of propylene and an α-olefin (excluding propylene). <4> The pellets for 3D printing according to <1> or <2>, wherein the crystalline propylene resin includes a random copolymer of propylene and an α-olefin (excluding propylene). <5> The pellets for 3D printing according to <1> or <2>, wherein the crystalline propylene resin includes a block copolymer of propylene and an α-olefin (excluding propylene) and a random copolymer of propylene and an α-olefin (excluding propylene). <6> The pellets for 3D printing according to any one of <1> to <5>, wherein the crystalline propylene resin has a melt flow rate (MFR) of 0.3 g / 10 min to 60 g / 10 min at 230°C under a load of 2.16 kg. <7> The pellets for 3D printing according to any one of <1> to <6>, wherein the olefin copolymer rubber is an ethylene-α-olefin-non-conjugated diene copolymer rubber. <8> The pellets for 3D printing according to any one of <1> to <7>, wherein the olefin copolymer rubber is an ethylene-propylene-non-conjugated diene copolymer rubber.

[0011] According to one embodiment of the present disclosure, pellets for three-dimensional printing are provided that are capable of forming a three-dimensional object with excellent shape retention.

[0012] FIG. 1 is a diagram for explaining the shape of a three-dimensional object produced in the example.

[0013] The pellets for three-dimensional printing of the present disclosure will be described in detail below, but the present disclosure is not limited to the following embodiments and can be implemented with appropriate modifications within the scope of the object of the present disclosure.

[0014] In the present disclosure, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the upper and lower limits. In the numerical ranges described in stages in the present disclosure, the upper or lower limit described in a certain numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Furthermore, in the numerical ranges described in the present disclosure, the upper or lower limit described in a certain numerical range may be replaced with a value shown in the examples. In the present disclosure, when referring to the amount of each component in a composition, if multiple substances corresponding to each component are present in the composition, the total amount of the multiple substances present in the composition is meant unless otherwise specified. In the present disclosure, the term "step" includes not only independent steps, but also steps that cannot be clearly distinguished from other steps, as long as the intended effect of the step is achieved. Furthermore, in the present disclosure, a combination of two or more preferred aspects is a more preferred aspect.

[0015] [Pellets for 3D modeling] The pellets for 3D modeling of the present disclosure contain a crosslinked product of a composition including 100 parts by mass of an olefin copolymer rubber, 55 to 150 parts by mass of a crystalline propylene resin, and 50 to 150 parts by mass of a softener.

[0016] The pellets for three-dimensional modeling according to the present disclosure contain a crosslinked product of a composition containing the specific components described above, and therefore can be used to form three-dimensional objects with excellent shape retention.

[0017] <Olefin-Based Copolymer Rubber> Examples of the olefin-based copolymer rubber include an α-olefin copolymer rubber made of two or more types of α-olefins, and an α-olefin / non-conjugated diene copolymer rubber made of two or more types of α-olefins and a non-conjugated polyene.

[0018] Examples of α-olefins include ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene, and 1-octene.

[0019] Examples of non-conjugated polyenes include linear non-conjugated dienes such as 1,4-hexadiene, 3-methyl-1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 4,5-dimethyl-1,4-hexadiene, 7-methyl-1,6-octadiene, 8-methyl-4-ethylidene-1,7-nonadiene, and 4-ethylidene-1,7-undecadiene; Cyclic non-conjugated dienes such as methyltetrahydroindene, 5-ethylidene-2-norbornene, 5-methylene-2-norbornene, 5-isopropylidene-2-norbornene, 5-vinylidene-2-norbornene, 6-chloromethyl-5-isopropenyl-2-norbornene, 5-vinyl-2-norbornene, 5-isopropenyl-2-norbornene, 5-isobutenyl-2-norbornene, cyclopentadiene and norbornadiene; trienes such as 2,3-diisopropylidene-5-norbornene, 2-ethylidene-3-isopropylidene-5-norbornene, 2-propenyl-2,2-norbornadiene and 4-ethylidene-8-methyl-1,7-nonadiene.

[0020] Among these, the non-conjugated polyene is preferably 5-ethylidene-2-norbornene, 5-vinyl-2-norbornene, cyclopentadiene, or 4-ethylidene-8-methyl-1,7-nonadiene, and more preferably 5-ethylidene-2-norbornene.

[0021] From the viewpoint of mechanical strength, the olefin copolymer rubber preferably contains structural units derived from ethylene, that is, the olefin copolymer rubber is more preferably an ethylene-α-olefin copolymer rubber.

[0022] The ethylene / α-olefin copolymer rubber is preferably an ethylene / α-olefin copolymer rubber or an ethylene / α-olefin / non-conjugated diene copolymer rubber, and more preferably an ethylene / α-olefin / non-conjugated diene copolymer rubber.

[0023] From the viewpoint of mechanical strength, the content of the structural units derived from ethylene is preferably 35% by mass to 95% by mass, more preferably 40% by mass to 90% by mass, and even more preferably 50% by mass to 80% by mass, based on the total amount of the ethylene-α-olefin copolymer rubber.

[0024] From the viewpoint of mechanical strength, the content of the structural units derived from the α-olefin is preferably 10% by mass to 60% by mass, and more preferably 20% by mass to 50% by mass, based on the total amount of the ethylene / α-olefin copolymer rubber.

[0025] The α-olefin in the ethylene-α-olefin copolymer rubber is preferably propylene from the viewpoint of compatibility with the crystalline propylene resin, and the ethylene-α-olefin copolymer rubber is more preferably an ethylene-propylene-non-conjugated diene copolymer rubber.

[0026] In the case of the ethylene / α-olefin / non-conjugated diene copolymer rubber, the content of the structural units derived from the non-conjugated diene is preferably 1% by mass to 10% by mass, and more preferably 2% by mass to 8% by mass, based on the total amount of the ethylene / α-olefin / non-conjugated diene copolymer rubber, from the viewpoint of rubber elasticity.

[0027] In the case of the ethylene-α-olefin-non-conjugated diene copolymer rubber, the iodine value is preferably 1 g / 100 g to 30 g / 100 g, and more preferably 3 g / 100 g to 25 g / 100 g.

[0028] From the viewpoint of mechanical strength, the ethylene-α-olefin copolymer rubber preferably has an intrinsic viscosity [η] measured in decalin (decahydronaphthalene) at 135°C of 2.0 to 8.0 dl / g, more preferably 3.0 to 7.0 dl / g, and even more preferably 3.3 to 7.0 dl / g. When the ethylene-α-olefin copolymer rubber is oil-extended using an oil extender such as a softener described below, the intrinsic viscosity [η] is determined by degreasing the ethylene-α-olefin copolymer rubber before measuring the intrinsic viscosity [η] and measuring the ethylene-α-olefin copolymer rubber alone. There are no particular limitations on the method for producing the ethylene-α-olefin copolymer rubber, and it can be produced by a known method. For example, the production method described in paragraphs

[0028] to

[0145] of WO 2018 / 181121 can be referenced.

[0029] <Crystalline Propylene Resin> In the present disclosure, "crystalline" refers to a property in which a heat of crystallization (ΔHc) is present when measured at a heating rate of 10 (°C / min) in differential scanning calorimetry (DSC).

[0030] The crystalline propylene resin may be a propylene homopolymer or a copolymer containing propylene as a structural unit, as long as it contains a structural unit derived from propylene. The copolymer containing propylene as a structural unit may be a random copolymer or a block copolymer.

[0031] The crystalline propylene resin preferably has a melt flow rate (MFR: ASTM D1238-65T, 230°C, 2.16 kg load) of 0.3 g / 10 min to 60 g / 10 min, more preferably 0.5 g / 10 min to 50 g / 10 min, and even more preferably 0.5 g / 10 min to 40 g / 10 min. When the melt flow rate of the crystalline propylene resin is within the above range, the interlayer adhesion and three-dimensional shape retention are excellent.

[0032] (Propylene-Based Block Copolymer) The crystalline propylene resin preferably contains a block copolymer containing structural units derived from propylene (hereinafter also referred to as "propylene-based block copolymer").

[0033] Specifically, the propylene-based block copolymer is preferably a block copolymer of propylene and an α-olefin (excluding propylene).

[0034] Examples of the α-olefin include α-olefins having 2 or 4 to 20 carbon atoms, preferably 2 or 4 to 12 carbon atoms, such as ethylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 2-methyl-1-propene, 3-methyl-1-pentene, 4-methyl-1-pentene, and 5-methyl-1-hexene. The α-olefins may be used alone or in combination of two or more. From the viewpoint of mechanical strength, the α-olefin is preferably ethylene.

[0035] In the propylene-based block copolymer, the content of structural units derived from propylene is preferably 50% by mass or more, more preferably 60% to 99% by mass, and even more preferably 70% to 99% by mass. The content of structural units derived from α-olefin is preferably 50% by mass or less, more preferably 1% to 40% by mass.

[0036] Examples of propylene-based block copolymers include those in which each block is formed by changing polymerization conditions (hereinafter referred to as "polymerized product"), and those in which two or more polymers (for example, propylene homopolymers and propylene-based random copolymers) are melt-kneaded before being mixed with other components, and among these, polymerized products are preferred.

[0037] The melt flow rate (MFR: ASTM D1238-65T, 230°C, 2.16 kg load) of the propylene-based block copolymer is in the range of 0.3 g / 10 min or more and 60 g / 10 min or less, preferably 0.5 g / 10 min or more and 50 g / 10 min or less, more preferably 0.5 g / 10 min or more and 40 g / 10 min or less. When the propylene-based block copolymer has a melt flow rate in the above range, the interlayer adhesion and three-dimensional shape retention are excellent.

[0038] (Propylene-Based Random Copolymer) The crystalline propylene resin preferably contains a random copolymer containing structural units derived from propylene (hereinafter also referred to as "propylene-based random copolymer").

[0039] Specifically, the propylene-based block copolymer is preferably a random copolymer of propylene and an α-olefin (excluding propylene).

[0040] Specific examples of the α-olefin are as described above.

[0041] In the propylene random copolymer, the content of structural units derived from propylene is preferably 50% by mass or more, more preferably 60% to 99% by mass, and even more preferably 70% to 99% by mass. The content of structural units derived from α-olefin is preferably 50% by mass or less, more preferably 1% to 40% by mass.

[0042] Examples of propylene-based random copolymers include propylene-ethylene random copolymers, propylene-ethylene-1-butene random copolymers, propylene-1-butene copolymers, propylene-1-octene copolymers, and propylene-1-hexene copolymers. Of these, the propylene-based random copolymer is preferably a propylene-ethylene random copolymer.

[0043] The melt flow rate (MFR: ASTM D1238-65T, 230°C, 2.16 kg load) of the propylene random copolymer is preferably 0.3 g / 10 min to 60 g / 10 min, more preferably 0.5 g / 10 min to 50 g / 10 min, and even more preferably 0.5 g / 10 min to 40 g / 10 min. When the melt flow rate of the propylene block copolymer is within the above range, the interlayer adhesion and three-dimensional shape retention are excellent.

[0044] From the viewpoint of further enhancing the three-dimensional shape retention, the crystalline propylene resin preferably contains a block copolymer of propylene and an α-olefin (excluding propylene), and a random copolymer of propylene and an α-olefin (excluding propylene).

[0045] The method for producing the propylene polymer is not particularly limited. For example, the propylene polymer can be produced by referring to the catalysts, production methods, and the like described in paragraphs 0022 to 0082 of WO 2012 / 102050.

[0046] In producing pellets for three-dimensional modeling, the content of the crystalline propylene resin in the raw material composition is preferably 55 parts by mass to 150 parts by mass, and more preferably 60 parts by mass to 140 parts by mass, relative to 100 parts by mass of the olefin copolymer rubber.

[0047] <Softener> Examples of softeners include: petroleum-based softeners such as process oil, lubricating oil, paraffin, liquid paraffin, petroleum asphalt, and vaseline; coal tar-based softeners such as coal tar and coal tar pitch; fatty oil-based softeners such as castor oil, rapeseed oil, soybean oil, and coconut oil; waxes such as tall oil, beeswax, carnauba wax, and lanolin; fatty acids or metal salts thereof such as ricinoleic acid, palmitic acid, stearic acid, barium stearate, and calcium stearate; naphthenic acid or metal soaps thereof; pine oil, rosin, or derivatives thereof; synthetic polymeric substances such as terpene resins, petroleum resins, and coumarone-indene resins; ester-based plasticizers such as dioctyl phthalate, dioctyl adipate, and dioctyl sebacate; and carbonate ester-based plasticizers such as diisododecyl carbonate. Examples of the softener include microcrystalline wax, sub(factice), liquid polybutadiene, modified liquid polybutadiene, liquid thiokol, and hydrocarbon-based synthetic lubricating oil. Among these, from the viewpoint of oil bleeding, the softener is preferably a petroleum-based softener.

[0048] In producing pellets for three-dimensional modeling, the content of the softener in the raw material composition is preferably 50 parts by mass to 150 parts by mass, and more preferably 60 parts by mass to 130 parts by mass, relative to 100 parts by mass of the olefin copolymer rubber.

[0049] <Crosslinking Agent> In producing pellets for three-dimensional modeling, the raw material composition preferably contains a crosslinking agent. Examples of crosslinking agents include organic peroxides, phenolic resins, sulfur, hydrosilicone compounds, amino resins, quinones or derivatives thereof, amine compounds, azo compounds, epoxy compounds, and isocyanates. Among these, from the viewpoints of rubber elasticity and fluidity, the crosslinking agent is preferably an organic peroxide.

[0050] Examples of organic peroxides include dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di-(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di-(t-butylperoxy)hexyne-3, 1,3-bis(t-butylperoxyisopropyl)benzene, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, n-butyl-4,4-bis(t-butylperoxy)valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, t-butylperoxybenzoate, t-butylperbenzoate, t-butylperoxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, and t-butylcumyl peroxide.

[0051] Among these, from the viewpoint of rubber elasticity, the organic peroxide is preferably 2,5-dimethyl-2,5-di-(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di-(t-butylperoxy)hexyne-3, or 1,3-bis(t-butylperoxyisopropyl)benzene, and more preferably 2,5-dimethyl-2,5-di-(t-butylperoxy)hexane.

[0052] In the production of pellets for three-dimensional modeling, the content of the crosslinking agent in the raw material composition is preferably 0.3 to 2 parts by mass, and more preferably 0.5 to 1.7 parts by mass, per 100 parts by mass of the olefin copolymer rubber. Within the above range, an excellent balance between rubber elasticity and interlayer adhesion is achieved.

[0053] <Crosslinking Aid> In producing pellets for three-dimensional modeling, the raw material composition preferably contains a crosslinking aid.

[0054] Examples of the crosslinking aid include peroxy crosslinking aids such as sulfur, p-quinone dioxime, p,p'-dibenzoylquinone dioxime, N-methyl-N-4-dinitrosoaniline, nitrosobenzene, diphenyl guanidine, and trimethylolpropane-N,N'-m-phenylenedimaleimide; divinylbenzene; triallyl cyanurate; polyfunctional methacrylates such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, and allyl methacrylate; and polyfunctional vinyl monomers such as vinyl butyrate and vinyl stearate.

[0055] In producing pellets for three-dimensional modeling, the content of the cross-linking aid in the raw material composition is preferably 0.1 parts by mass to 1.0 parts by mass, and more preferably 0.2 parts by mass to 1.2 parts by mass, relative to 100 parts by mass of the olefin copolymer rubber.

[0056] <Crossover Temperature> The pellets for three-dimensional printing according to the present disclosure preferably do not have a crossover temperature in the range of 40° C. to 200° C. Since the crossover temperature does not exist in the range of 40° C. to 200° C., the pellets have excellent shape retention during three-dimensional printing.

[0057] <Storage Modulus> The pellets for three-dimensional modeling according to the present disclosure have a storage modulus of 3.0 × 10 at 140°C. ４ MPa to 8.0 x 10 ４ MPa, and preferably 3.0 × 10 ４ MPa to 7.0 x 10 ４ It is more preferable that the storage modulus is 3.0×10 MPa.４ On the other hand, when the storage modulus is 8.0×10 MPa or more, the interlayer adhesion is excellent and warping is unlikely to occur. ４ When the storage modulus at 140° C. is 3.0×10 or less, the pellets for three-dimensional printing according to the present disclosure have excellent correlation adhesion and are less likely to collapse due to heat. ４ MPa to 8.0 x 10 ４ It is preferable that the compressive strength is 100 MPa or less and that the compressive strength does not have a crossover temperature.

[0058] The crossover temperature and storage modulus are measured by the following method.

[0059] The specimens were press-molded at 200°C for 5 minutes using a 100-ton electric automatic press (manufactured by Shoji Co., Ltd.), followed by cooling and pressing at room temperature (25°C) for 3 minutes to obtain test specimens with a thickness of 1.5 mm and a diameter of 25 mm. The obtained test specimens were cooled from 200°C to 40°C using a rheometer (product name "ARES-G2", manufactured by TA Instruments Co., Ltd.) in a nitrogen atmosphere at a frequency of 1 Hz and a temperature decrease rate of 5°C / min to obtain the storage modulus (G') and loss modulus (G"). The temperature at which G' and G" coincide was defined as the crossover temperature.

[0060] <Tensile Strength and Tensile Breaking Elongation> The pellets for 3D manufacturing according to the present disclosure preferably have a tensile strength of 15 MPa to 50 MPa, and more preferably 20 MPa to 45 MPa. The pellets for 3D manufacturing according to the present disclosure preferably have a tensile breaking elongation of 100% to 800%, and more preferably 150% to 700%.

[0061] The tensile strength and tensile elongation at break are measured by the following method.

[0062] Using a 2 mm nozzle, a rectangular prism (170 mm x 170 mm x 100 mm high) with a thickness of 2 mm and a layer pitch of 1 mm was 3D-printed, and a test piece (a 1BA-type dumbbell as specified in JIS K 7161-2:2014) was sampled from its wall. The longitudinal direction of the sample was perpendicular to the layering direction. Using the obtained sample, a tensile test was performed in accordance with JIS K 7161-2:2014 at a test temperature of 23°C and a tensile speed of 500 mm / min to measure the tensile elongation at break and the tensile strength.

[0063] <Permanent Tensile Set> The pellets for three-dimensional fabrication according to the present disclosure preferably have a permanent tensile set of 20% to 80%, and more preferably 20% to 70%.

[0064] The tensile set is measured by the following method.

[0065] Using a 2 mm nozzle, a rectangular prism (170 mm x 170 mm x 100 mm high) with a thickness of 2 mm and a layer pitch of 1 mm is three-dimensionally molded, and a test piece (JIS No. 3 dumbbell specified in JIS K 6273) is sampled from the wall. The longitudinal direction of the sample is perpendicular to the layering direction. Using the obtained sample, the tensile permanent set is measured in accordance with JIS K 6273 at a test temperature of 100°C, a strain of 25%, and for 22 hours.

[0066] The pellets for three-dimensional modeling according to the present disclosure can be produced, for example, by mixing raw materials other than the softener, and then granulating the mixture in an extruder while injecting the softener into the cylinder.

[0067] According to the pellets for three-dimensional modeling of the present disclosure, a three-dimensional model that has excellent shape retention can be formed.

[0068] The three-dimensional object manufacturing apparatus may be a material extrusion type three-dimensional object manufacturing apparatus. There are no particular limitations on the material extrusion type three-dimensional object manufacturing apparatus, and any known apparatus or known apparatus configuration may be used.

[0069] The three-dimensional object manufacturing apparatus may include, for example, a cylinder to which a three-dimensional modeling material is supplied, a nozzle provided on the cylinder downstream in the direction of discharging the three-dimensional modeling material and for discharging the three-dimensional modeling material, and a heating means provided on the cylinder for heating and melting the three-dimensional modeling material. By using the three-dimensional object manufacturing apparatus, a three-dimensional object can be manufactured by extruding the heated and melted three-dimensional modeling material from the nozzle and layering the three-dimensional modeling material extruded from the nozzle.

[0070] The cylinder may have a screw therein that kneads the material. The three-dimensional object manufacturing apparatus may further include a table device that is disposed opposite the nozzle and receives the molten material from the nozzle. The three-dimensional object manufacturing apparatus may further include a control means that controls the spatial coordinates of the substrate and the nozzle, and the amount of three-dimensional object material extruded from the nozzle. The control means is preferably a control means that controls the discharge of the three-dimensional object material from the nozzle, and controls the movement of the nozzle and / or the table device in the X-axis, Y-axis, and Z-axis directions relative to a reference plane.

[0071] The method for forming a three-dimensional object according to the present disclosure may further include, as another step, for example, a processing step of processing the three-dimensional object formed in the forming step.

[0072] Three-dimensional objects that can be molded using the resin composition for three-dimensional printing are not particularly limited, but examples include automobile objects (e.g., console parts, switch parts, door trim parts, instrument panel parts, clips, covers, etc.), electrical appliance objects (electrical appliance parts, housings, etc.), furniture components, building components, construction materials, aircraft parts, toys, shoes, sporting goods, decorative items, cases, etc. In particular, the resin composition for three-dimensional printing according to the present disclosure is suitable for molding building components and automotive objects because thermal collapse is suppressed when the composition is used to mold objects.

[0073] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples as long as it does not depart from the gist of the invention. Unless otherwise specified, "parts" are based on mass. The crossover temperature, storage modulus, tensile elongation at break, tensile strength, and tensile permanent set were measured by the methods described above. When a crossover temperature was present in the range of 40°C to 200°C, "Yes" was entered in the crossover temperature column in Table 1, and when no crossover temperature was present, "No" was entered. Furthermore, in Comparative Examples 1, 2, and 4, a three-dimensional object could not be formed, and the above physical properties could not be measured, so "-" was entered.

[0074] The materials used in the examples and comparative examples are shown below.

[0075] Olefin copolymer rubber: ethylene-propylene-non-conjugated polyene copolymer, ethylene content = 63% by mass, propylene content = 32.5% by mass, non-conjugated diene type: 5-ethylidene-2-norbornene, non-conjugated diene content = 4.5% by mass, non-conjugated diene content (iodine value) = 13, intrinsic viscosity [η] = 3.4 (dl / g) Propylene-ethylene block copolymer MFR (230°C, 2.16 kg load) = 9 g / 10 min, melting point 160°C Propylene-ethylene random polymer MFR (230°C, 2.16 kg load) = 9 g / 10 min, melting point 140°C Softener: paraffin-based process oil (product name "Diana Process Oil (registered trademark) PW-100", Idemitsu Kosan Co., Ltd.) Crosslinking agent: 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane (product name "Perhexa 25B", manufactured by NOF Corporation) Crosslinking coagent: divinylbenzene (product name "DVB-810", manufactured by Nippon Steel & Sumikin Chemical Co., Ltd.) Propylene-1-butene random copolymer MFR (190°C, 2.16 kg load) = 9 g / 10 min, melting point 58°C Ethylene-1-butene random copolymer MFR (190°C, 2.16 kg load) = 9 g / 10 min, melting point 100°C

[0076] Examples 1 to 5 and Comparative Examples 1 to 4 All of the raw materials listed in Table 1 were kneaded using an extruder (product number KTX-30, manufactured by Kobe Steel, Ltd.; cylinder temperatures: C1 = 50°C, C2 = 90°C, C3 = 100°C, C4 = 120°C, C5 = 180°C, C6 = 200°C, C7 to C14 = 200°C; die temperature: 200°C; screw rotation speed: 500 rpm; extrusion rate: 40 kg / h) to obtain pellets.

[0077] The pellets thus obtained were used to produce three-dimensional objects, and the shape retention (interlayer adhesion, thermal collapse, and warpage) was evaluated using the following methods.

[0078] <Interlayer Adhesion> Using a material extrusion-type three-dimensional modeling device ("GEM444D" manufactured by S.Lab Co., Ltd., nozzle diameter: 3 mm) and application software ("Simplify3D" manufactured by Simplify3D), a rectangular prism (170 mm x 170 mm x 100 mm high) with a 2 mm nozzle, a thickness of 2 mm, and a layer pitch of 1 mm was 3D-modeled, and a test piece (1BA-type dumbbell as defined in JIS K 7161-2:2014) was sampled from the wall of the 3D model. The longitudinal direction of the sample was parallel to the layering direction. Using the obtained sample, a tensile test was performed in accordance with JIS K 7161-2:2014 at a test temperature of 23°C and a tensile speed of 500 mm / min to evaluate interlayer adhesion. The evaluation criteria are as follows: A: Tensile elongation at break is 50% or more. B: Tensile elongation at break is less than 50%. C: Delamination occurs during preparation of a tensile test specimen.

[0079] <Warping and thermal collapse> A measurement object as shown in Figure 1 was manufactured using a material extrusion type three-dimensional object manufacturing device (S.Lab Co., Ltd., "GEM444D," nozzle diameter: 3 mm) and application software (Simplify3D, Simplify3D). Specifically, a three-dimensional object was manufactured by sequentially layering molten pellets on a substrate based on three-dimensional coordinate data. <3D data> - Cylinder with a diameter of 70 mm and a height of 120 mm <Setting parameters for measurement object> - 3 mm nozzle - Building speed: 600 mm / min - Nozzle temperature: 200°C - Layer pitch: 1.5 mm - Width: 3.6 mm

[0080] The evaluation criteria are as follows. From the viewpoint of shape retention, the occurrence of thermal collapse and warping was visually confirmed. (Thermal collapse) A: The object shown in Figure 1 could be formed. B: Partial thermal collapse occurred, and a different object from the object shown in Figure 1 was obtained. C: Thermal collapse occurred, and a different object could not be obtained. (Warping) A: The object shown in Figure 1 could be formed. B: Partial warping occurred, and a different object from the object shown in Figure 1 was obtained. C: Warping occurred, and a different object could not be obtained.

[0081]

[0082] As shown in Table 1, Examples 1 to 6 contain a crosslinked composition comprising 100 parts by mass of an olefin copolymer rubber, 55 to 150 parts by mass of a crystalline propylene resin, and 50 to 150 parts by mass of a softener, and thus were able to produce a three-dimensional object with excellent shape retention. On the other hand, in Comparative Example 1, the content of the crystalline propylene resin was less than 55 parts by mass, resulting in poor correlation adhesion and failure to produce a three-dimensional object due to thermal collapse. In Comparative Example 2, the content of the crystalline propylene resin was more than 150 parts by mass, resulting in poor correlation adhesion and failure to produce a three-dimensional object due to warping. Comparative Examples 3 and 4 do not contain an olefin copolymer rubber, resulting in poor correlation adhesion and failure to produce a three-dimensional object due to warping.

[0083] The disclosure of Japanese Patent Application No. 2023-168595, filed on September 28, 2023, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A pellet for three-dimensional modeling, comprising a crosslinked body of a composition including 100 parts by mass of an olefin copolymer rubber, 55 to 150 parts by mass of a crystalline propylene resin, and 50 to 150 parts by mass of a softener.

2. Storage modulus at 140°C is 3.0 x 10 ４ MPa to 8.0 x 10 ４ The pellet for three-dimensional printing according to claim 1 , wherein the compressive strength is equal to or less than 100 MPa and the pellet has no crossover temperature.

3. The pellet for three-dimensional printing according to claim 1 or 2, wherein the crystalline propylene resin contains a block copolymer of propylene and an α-olefin (excluding propylene).

4. The pellet for three-dimensional printing according to claim 1 or 2, wherein the crystalline propylene resin contains a random copolymer of propylene and an α-olefin (excluding propylene).

5. The pellets for three-dimensional printing according to claim 1 or 2, wherein the crystalline propylene resin includes a block copolymer of propylene and an α-olefin (excluding propylene), and a random copolymer of propylene and an α-olefin (excluding propylene).

6. The pellets for three-dimensional printing according to claim 1 or 2, wherein the crystalline propylene resin has a melt flow rate (MFR) of 0.3 g / 10 min to 60 g / 10 min at 230° C. under a load of 2.16 kg.

7. The pellet for three-dimensional printing according to claim 1 or 2, wherein the olefin copolymer rubber is an ethylene-α-olefin-non-conjugated diene copolymer rubber.

8. The pellet for three-dimensional printing according to claim 1 or 2, wherein the olefin copolymer rubber is an ethylene-propylene-non-conjugated diene copolymer rubber.

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