Resin composition for 3D printing, 3D printed object, and method for producing 3D printed object

Abstract

A resin composition according to the present disclosure is for 3D printing. The resin composition contains polypropylene, a propylene-α-olefin copolymer, and an elastomer that is immiscible with polypropylene. Let WPP be the percentage by weight of the polypropylene contained in the resin composition and let WPOR be the percentage by weight of the propylene-α-olefin copolymer, in which case WPP > WPOR is satisfied.

Description

Resin composition for three-dimensional molding, three-dimensional molded object, and method for manufacturing a three-dimensional molded object.

[0001] This disclosure relates to a resin composition for three-dimensional molding, a three-dimensional molded object, and a method for manufacturing a three-dimensional molded object.

[0002] In recent years, three-dimensional modeling technology, also known as 3D printing technology, has attracted attention, and among them, fused deposition modeling (FDM) is one of the representative modeling methods. FDM is a method of creating three-dimensional objects by melting resin filament or resin pellets at high temperatures, extruding them through a nozzle, and layering the resin while moving the nozzle along the cross-section of the object. Among FDM methods, the method that uses resin pellets is also called the direct pellet method. The direct pellet method does not require processing the resin into a filament, and modeling can be done directly from resin pellets, so it is low cost and offers a high degree of freedom in material selection, and its use is progressing in industrial applications.

[0003] For example, Patent Document 1 describes a resin composition for three-dimensional molding containing 40% to 99% by weight of a resin (A) selected from a specific propylene-based block copolymer (a-1) and a specific propylene-based resin composition (a-2), satisfying the following properties (A-i) to (A-iii), and 1% to 60% by weight of a filler (B) which is at least one of an inorganic filler or an organic filler. Property (A-i) is that the melting peak temperature Tm measured by the DSC method is 110°C to 150°C, property (A-ii) is that in the temperature-loss tangent curve obtained by solid viscoelasticity measurement, the tanδ curve has a single peak below 0°C, and property (A-iii) is that the melt flow rate (MFR) at 230°C and a load of 2.16 kg is 0.5 g / 10 min to 200 g / 10 min.

[0004] Patent Document 2 describes a material for a three-dimensional molding apparatus comprising a thermoplastic resin composition (S), wherein the amount of heat absorbed during melting (ΔH-D), defined by the area of ​​the peak observed on the highest temperature side of the melting endothermic curve measured using a differential scanning calorimeter (DSC) by holding the thermoplastic resin composition (S) at -10°C for 5 minutes in a nitrogen atmosphere and then raising the temperature at 10°C / min, is 0 J / g or more and 80 J / g or less. Patent Document 2 states that the thermoplastic resin composition (S) may include homopolypropylene and propylene-olefin copolymers, etc.

[0005] Patent Document 3 describes a resin molding material for a three-dimensional molding apparatus, which contains a thermoplastic resin (A) in a volume of 30 to 80% by mass, a thermoplastic elastomer (B) in a volume of 1 to 45% by mass, a modifier (C) in a volume of 0.5 to 15% by mass, and a tackifying resin (D) in a volume of 5 to 35% by mass. However, if the thermoplastic elastomer (B) is a functional group-imparting thermoplastic elastomer, the modifier (C) may not be included. Specifically, styrene-based elastomers are used as thermoplastic elastomers.

[0006] Patent Document 4 describes a resin molding material for a three-dimensional molding apparatus containing a thermoplastic resin, a modifier, an elastomer, and a filler. The filler has an average particle size of 0.5 to 100 μm and an aspect ratio of 10 to 200. Homopolypropylene and block polypropylene are used as the thermoplastic resin. Specifically, styrene copolymers and ethylene-octene copolymers are used as the elastomer.

[0007] Patent Document 5 describes an inorganic substance powder-filled resin composition containing a thermoplastic resin and an inorganic substance powder in a mass ratio of 50:50 to 10:90. The thermoplastic resin contains a first resin and a second resin, the first resin being a propylene-α-olefin copolymer and the second resin being a polyolefin resin different from the first resin. The content of the first resin is 80 parts by mass or more and 95 parts by mass or less per 100 parts by mass of the thermoplastic resin. Specifically, ethylene-propylene copolymer is used as the propylene-α-olefin copolymer. Specifically, propylene homopolymer and block polypropylene are used as the polyolefin resin.

[0008] Patent document 6 describes a filament for three-dimensional molding that contains an olefin-based resin composition (α) satisfying a specific formula [1], wherein the olefin-based resin composition (α) contains a resin composition (B), and the resin composition (B) contains a cyclic olefin resin. Specifically, the olefin-based resin composition (α) is a propylene-ethylene random polymer, etc.

[0009] Japanese Patent Publication No. 2024-173825, Japanese Patent Publication No. 2020-175570, Japanese Patent Publication No. 2020-157609, Japanese Patent Publication No. 2018-131497, Japanese Patent Publication No. 2023-77472, International Publication No. 2021 / 066102

[0010] This disclosure aims to provide a resin composition for three-dimensional molding that exhibits excellent impact resistance and bending strength, a three-dimensional object made therefrom, and a three-dimensional molding method.

[0011] Examples of embodiments of the present disclosure are listed in the following items [1] to

[12] . [1] A resin composition for three-dimensional molding, wherein the resin composition contains polypropylene, a propylene-α-olefin copolymer, and an elastomer incompatible with the polypropylene, and the weight % of the polypropylene contained in the resin composition is W ＰＰ , the weight % of the propylene-α-olefin copolymer is W ＰＯＲ When that happens, W ＰＰ >W ＰＯＲA resin composition that satisfies the following conditions. [2] The resin composition according to item 1, wherein the polypropylene comprises block copolymer polypropylene. [3] The resin composition according to item 1 or 2, wherein the propylene-α-olefin copolymer comprises propylene-1-butene copolymer. [4] The resin composition according to any one of items 1 to 3, wherein the immiscible elastomer comprises ethylene-α-olefin copolymer. [5] The resin composition according to item 4, wherein the ethylene-α-olefin copolymer comprises ethylene-1-butene copolymer. [6] The resin composition according to item 3, wherein the immiscible elastomer comprises ethylene-1-butene copolymer. [7] The resin composition according to any one of items 1 to 6, further comprising reinforcing fibers. [8] W ＰＰ ≤ 2.0 × W ＰＯＲ A resin composition according to any one of items 1 to 7 that satisfies the following conditions. [9] A resin composition according to any one of items 1 to 8 that contains 10% by weight or more and 90% by weight or less of the polypropylene based on the total weight of the resin composition.

[10] A resin composition according to any one of items 1 to 9 that contains 5% by weight or more and 50% by weight or less of the propylene-α-olefin copolymer based on the total weight of the resin composition.

[11] A three-dimensional molded object formed using a resin composition according to any one of items 1 to 10.

[12] A three-dimensional molded object according to item 11 that has a hollow structure.

[13] A method for manufacturing a three-dimensional molded object, comprising a lamination step of laminating strands formed by melting a resin composition according to any one of items 1 to 10 and extruding it from a nozzle.

[0012] According to this disclosure, it is possible to provide a resin composition for three-dimensional molding with excellent impact resistance and bending strength, a three-dimensional molded object made therefrom, and a three-dimensional molding method.

[0013] Figure 1 is a schematic diagram of a three-dimensional object having a hollow structure used for evaluating the formability and appearance of the object according to this disclosure. Figure 2 is a schematic diagram of a three-dimensional object having a hollow structure used for evaluating the impact strength and bending strength (3D printed test piece (90°)) according to this disclosure.

[0014] Hereinafter, one embodiment of the present disclosure will be described in detail, but the scope of the present disclosure is not limited to the embodiment described herein, and various modifications can be made without departing from the gist of the present disclosure. In addition, when a plurality of upper limit values and lower limit values are described for a specific parameter, any upper limit value and lower limit value among these upper limit values and lower limit values can be combined to form a suitable numerical range.

[0015] <<Resin Composition>> The resin composition according to the present disclosure is a resin composition for three-dimensional modeling, and the resin composition contains polypropylene, a propylene-α-olefin copolymer, and an elastomer that is immiscible with the polypropylene. Based on the total weight of the resin composition, the weight% of the polypropylene contained in the resin composition is defined as W ＰＰ , and the weight% of the propylene-α-olefin copolymer is defined as W ＰＯＲ , W ＰＰ >W ＰＯＲThe present disclosure satisfies the following conditions. The resin composition having this configuration exhibits excellent impact resistance and flexural strength. The reasons for this are not limited to theory but are presumed to be as follows: (1) By adding an elastomer incompatible with polypropylene (hereinafter also referred to as "PP"), the elastomer incompatible with PP is dispersed in the PP, preferably forming a sea-island structure. This is thought to improve impact resistance as the elastomer incompatible with PP plays a role in dispersing and mitigating energy when an impact is applied. (2) By adding a relatively small weight percent of propylene-α-olefin copolymer (hereinafter also referred to as "P-αOR"), crystallization of PP is suppressed without significantly impairing the mechanical properties of PP, and the amorphous component increases. This is thought to improve impact resistance as the mobility of molecular chains increases and toughness improves. (3) Furthermore, P-αOR has high compatibility with PP due to the presence of a propylene component, and since P-αOR is compatible with PP, the crystallization rate of PP is suppressed by the addition of P-αOR. As a result, the molten state during molding is maintained for a longer period, and the fusion time between adjacent strands is extended. As a result, the adhesion strength between strands is improved, and it is thought that the impact resistance and flexural strength in the 90° direction with respect to the lamination direction (the direction that breaks the interface between laminated strands) are improved. It is thought that the resin composition of this disclosure has excellent impact resistance and flexural strength due to at least the estimated mechanisms described in (1) to (3) above, which occur due to the presence of PP-compatible P-αOR in PP and PP-incompatible elastomer in PP.

[0016] <Composition> (Polypropylene) The resin compositions of this disclosure contain polypropylene. Examples of polypropylene include polypropylene homopolymer, random copolymer polypropylene (also referred to as "rPP" in this disclosure), and block copolymer polypropylene (also referred to as block polypropylene; also referred to as "bPP" in this disclosure). rPP is typically a random copolymer of propylene, which is the main component, and a small amount of comonomer such as ethylene. bPP is typically a block copolymer of propylene, which is the main component, and a small amount of comonomer such as ethylene, and more specifically, may consist of a polypropylene homopolymer phase and an ethylene-propylene copolymer phase or polyethylene phase. Block copolymer polypropylene may have a sea-island structure in which island phases of ethylene-propylene copolymer phase or polyethylene phase are dispersed in a sea phase of polypropylene homopolymer phase, and ethylene-propylene copolymer (EPR) may be present around the ethylene-propylene copolymer phase or polyethylene phase. Here, "main component" of polypropylene means that it constitutes the largest amount in the copolymer in terms of molar ratio. The ethylene content in rPP and bPP is not limited, but may be, for example, 1 to 20 mol%, or 1 to 10 mol%.

[0017] From the viewpoint of impact resistance, flexural strength, and moldability, polypropylene is preferably made to contain bPP. When the resin composition contains bPP as a polyolefin, the addition of P-αOR suppresses the crystallization of bPP and increases the amorphous component. This increases the mobility of the molecular chains and improves toughness, thus further improving impact resistance. Furthermore, the addition of P-αOR suppresses the crystallization rate of bPP. As a result, the molten state is maintained for a longer period during molding, and the fusion time between adjacent strands is extended. Consequently, the adhesion strength between strands is improved, and the impact resistance and flexural strength in the 90° direction relative to the lamination direction are further improved.

[0018] The melt flow rate (MFR) of polypropylene at 230°C under a 2.16 kg load is preferably 0.5 to 100 g / 10 min, and may be, for example, 3 to 50 g / 10 min. When the MFR is 0.5 g / 10 min or more, the fluidity of the resin is high, melt fracture during nozzle discharge is suppressed, and the appearance quality of the shaped article is improved. On the other hand, when the MFR is 100 g / 10 min or less, the melt viscosity is not excessively high, the strands immediately after shaping are more effectively prevented from sagging, and the shaping performance is further improved. By appropriately combining polypropylene resins having different MFRs, for example, a plurality of types of polypropylenes (homopolymers, random copolymers, block copolymers) and the like, the melt viscosity can be adjusted according to the purpose.

[0019] The content of polypropylene is preferably 10 wt% to 90 wt% based on the total weight of the resin composition. The lower limit of the polypropylene content may be, for example, 15 wt% or more, 20 wt% or more, or 30 wt% or more. The upper limit of the polypropylene content, which can be arbitrarily combined with these lower limit values, may be, for example, 80 wt% or less, 70 wt% or less, or 60 wt% or less. When the content of polypropylene is within these ranges, the impact resistance, flexural strength, and shaping performance are more excellent.

[0020] (Other Thermoplastic Resins) The resin composition of the present disclosure may contain other thermoplastic resins in addition to polypropylene. Examples of other thermoplastic resins include, but are not limited to, general-purpose plastics, engineering plastics, and super engineering plastics.

[0021] Examples of general-purpose plastics include polyolefins excluding polypropylene, such as polyethylene and polybutene, as well as polyvinyl chloride (PVC), polyvinylidene chloride, polystyrene (PS), polyvinyl acetate (PVAc), polytetrafluoroethylene (PTFE), acrylonitrile butadiene styrene resin (ABS resin), styrene acrylonitrile copolymer (AS resin), and acrylic resins.

[0022] Examples of engineering plastics include polyamide (PA), polyacetal (POM), polycarbonate (PC), modified polyphenylene ether (m-PPE, modified PPE, PPO), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), syndiotactic polystyrene (SPS), cyclic polyolefin (COP), and the like.

[0023] Examples of super engineering plastics include polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE), polysulfone (PSF), polyethersulfone (PES), amorphous polyarylate (PAR), polyether ether ketone (PEEK), thermoplastic polyimide (PI), polyamideimide (PAI), and the like.

[0024] The content of the other thermoplastic resin may be, for example, 1 wt% to 20 wt%, 1 wt% to 10 wt%, or 1 wt% to 5 wt%, based on the total weight of the resin composition. When the content of the other thermoplastic resin falls within these ranges, the impact resistance, flexural strength and moldability are more excellent.

[0025] (Elastomer) The resin composition of the present disclosure further contains, in addition to polypropylene, a propylene-α-olefin copolymer (P-αOR) and an elastomer that is immiscible with polypropylene. The P-αOR and the elastomer immiscible with polypropylene are elastomers and have rubber elasticity. The rubber elasticity refers to a property that when a load is applied to the resin, the shape of the resin deforms, and when the load applied to the resin is removed, the shape of the resin tends to return to its original shape. Since the resin composition further contains P-αOR and the elastomer immiscible with polypropylene, the impact resistance and flexural strength are excellent.

[0026] The elastomer refers to a thermoplastic resin having rubber elasticity, and is preferably a thermoplastic resin having a tensile modulus at 25°C of 6.0×10 ８ Pa or less. The tensile modulus is measured in accordance with JIS K7161-2:2014, the test speed is 1 mm / min, and the test piece is a Type 1A test piece. The total length of the injection molded article is 170 mm, and the thickness of the injection molded article is 2.5 mm.

[0027] An elastomer incompatible with polypropylene is an elastomer other than a propylene-α-olefin copolymer that, when melt-kneaded with polypropylene, does not substantially form a single phase, but rather forms a multi-phase structure in which the polypropylene phase and the elastomer phase are phase-separated. An elastomer incompatible with polypropylene can be confirmed by observing a cross-section of the mixture obtained by melt-kneading polypropylene with polypropylene using an electron microscope or similar device, and analyzing the dispersed phase derived from the elastomer incompatible with polypropylene.

[0028] From the viewpoint of impact resistance and flexural strength, the number of carbon atoms in the α-olefin in P-αOR is preferably 3 or more, and preferably 10 or less, 8 or less, or 5 or less. Examples of α-olefins in P-αOR include 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 3,3-dimethyl-1-butene, 4-methyl-1-pentene, and 1-octene. The α-olefin may be used alone or in combination of two or more. A propylene-1-butene copolymer (PBR) is preferred as the P-αOR.

[0029] From the viewpoint of impact resistance and flexural strength, it is preferable that the elastomer incompatible with polypropylene contains an α-olefin copolymer. More preferably, the α-olefin copolymer incompatible with polypropylene is a copolymer that contains structural units derived from α-olefin and structural units derived from other olefins different from said α-olefin.

[0030] From the viewpoint of impact resistance and flexural strength, the number of carbon atoms in the α-olefin copolymer that is incompatible with polypropylene is preferably 2 or more, or 3 or more, and preferably 10 or less, 8 or less, or 5 or less. Examples of α-olefins in the α-olefin copolymer that is incompatible with polypropylene include 1-butene, 1-pentene, 1-hexene, 3-methyl-1-butene, 3,3-dimethyl-1-butene, 4-methyl-1-pentene, and 1-octene. The number of carbon atoms in the other olefins in the α-olefin copolymer that is incompatible with polypropylene is preferably 2 or more, or 3 or more, and preferably 10 or less, 8 or less, or 5 or less. Examples include ethylene and butene.

[0031] Preferred examples of α-olefin copolymers incompatible with polypropylene include ethylene-α-olefin copolymers and butene-α-olefin copolymers, with ethylene-α-olefin copolymer (E-αOR) being more preferred. Even more preferably, the α-olefin copolymer incompatible with polypropylene includes ethylene-1-butene copolymer (EBR). Both polypropylene and PBR have propylene as a constituent unit, and both PBR and EBR have butene as a constituent unit, resulting in high affinity for the resin as a whole, and consequently, a tendency towards superior impact resistance.

[0032] The melt flow rate (MFR) of the elastomer is preferably 0.5 to 20 g / 10 min or 0.8 to 10 g / 10 min at 230°C and a 2.16 kg load. Within these ranges, a good viscoelastic balance is achieved when mixed with polyolefin resin, improving moldability and the appearance of the molded object. Specifically, if the MFR of the elastomer is 0.5 g / 10 min or higher, the overall fluidity of the resin when mixed with polyolefin is increased, suppressing melt fracture during nozzle extrusion and improving the appearance quality of the molded object. On the other hand, if the MFR is 20 g / 10 min or lower, the overall melt viscosity of the resin when mixed with polyolefin is not too high, more effectively preventing strand sagging immediately after molding and further improving moldability.

[0033] The elastomer content is preferably 5% to 50% by weight, based on the total weight of the resin composition. The lower limit of the elastomer content is preferably 10% or more by weight, 15% or more by weight, or 20% or more by weight. The upper limit of the elastomer content, which can be optionally combined with these lower limits, is preferably 45% or less by weight, 40% or less by weight, or 35% or less by weight. When the elastomer content is within these ranges, impact resistance and flexural strength are further improved.

[0034] The lower limit of the content of propylene-α-olefin copolymer (P-αOR) and the elastomer incompatible with polypropylene is preferably 1% by weight or more, 5% by weight or more, 10% by weight or more, or 15% by weight or more, based on the total weight of the resin composition. The upper limit of the content of P-αOR and the elastomer incompatible with polypropylene, which can be optionally combined with these lower limits, is preferably 50% by weight or less, 40% by weight or less, 35% by weight or less, 30% by weight or less, or 25% by weight or less, respectively. When the content of P-αOR and the elastomer incompatible with polypropylene are within these ranges, impact resistance and flexural strength are further improved.

[0035] The weight percentage of polypropylene (PP) contained in the resin composition of this disclosure is W ＰＰ , the weight % of olefin copolymer (OR) is W ＯＲ In that case, W is preferable. ＰＰ >W ＯＲ That is, the weight ratio of PP to OR (W ＰＰ / W ＯＲ The lower limit of ) is preferably greater than 1.0, for example, 1.1 or more, or 1.2 or more. The weight ratio (W) that can be arbitrarily combined with these lower limits is ＰＰ / W ＯＲ The upper limit of ) is preferably less than 3.0, for example, 2.5 or less, 2.0 or less, or 1.5 or less. Weight ratio of PP to OR (W ＰＰ / W ＯＲ When these values ​​are within these ranges, impact resistance and bending strength are further improved.

[0036] The weight percentage of polypropylene (PP) contained in the resin composition of this disclosure is W ＰＰ , the weight % of propylene-α-olefin copolymer (P-αOR) is W ＰＯＲ When that happens, W ＰＰ >W ＰＯＲ That is, the weight ratio of PP to P-αOR (W ＰＰ / W ＰＯＲ The lower limit of ) is greater than 1.0, and may be, for example, 1.1 or more, 1.2 or more, or 1.5 or more. The weight ratio (W) that can be arbitrarily combined with these lower limits is ＰＰ / W ＰＯＲ The upper limit of ) is preferably 5.0 or less, for example 5.0 or less, 3.0 or less, or 2.0 or less (i.e., W ＰＰ ≤ 2.0 × W ＰＯＲ ) may be. Weight ratio of PP to P-αOR (W ＰＰ / W ＰＯＲ When these values ​​are within these ranges, impact resistance and bending strength are further improved.

[0037] The weight percentage of block polypropylene (bPP) contained in the resin composition of this disclosure is W ｂＰＰ , the weight % of propylene-α-olefin copolymer (P-αOR) is W ＰＯＲ In that case, W is preferable. ｂＰＰ >W ＰＯＲ Therefore, the weight ratio of bPP to P-αOR (W ｂＰＰ / W ＰＯＲ The lower limit of ) is preferably greater than 1.0, for example, 1.1 or more, or 1.2 or more. The weight ratio (W) that can be arbitrarily combined with these lower limits is ｂＰＰ / W ＰＯＲ The upper limit of ) is preferably 5.0 or less, for example, 4.0 or less, 3.0 or less, or 2.0 or less. The weight ratio of bPP to P-αOR (W ｂＰＰ / W ＰＯＲ When these values ​​are within these ranges, impact resistance and bending strength are further improved.

[0038] (Fillers) The resin compositions of this disclosure may further contain fillers. Examples of fillers include inorganic or organic fillers such as carbon fibers, carbon black, graphite, glass fibers, glass flakes, talc, mica, clay, silica, calcium carbonate, alumina, and magnesia. By adding these fillers, the rigidity, dimensional stability, surface properties, thermal conductivity, design, electrical conductivity, and cost of the molded object can be adjusted as appropriate. In particular, from the viewpoint of improving the mechanical strength of the molded object, it is preferable that the resin composition further contains reinforcing fibers such as carbon fibers and glass fibers.

[0039] For example, the resin composition may further contain carbon fibers. Examples of carbon fibers include polyacrylonitrile (PAN) carbon fibers, pitch carbon fibers, and mixtures thereof. By including carbon fibers in the resin composition, improvements in the mechanical strength, dimensional stability, thermal conductivity, and surface texture of the molded object can be expected. The carbon fibers may be in the form of short fibers, long fibers, or continuous fibers. These carbon fibers may be sized to improve adhesion with the resin, and as a sizing agent, a sizing agent that is compatible with the resin constituting the resin composition, such as polyolefins, is preferred, such as epoxy-based and olefin-based sizing agents.

[0040] The reinforcing fiber content may be, for example, 5% to 50% by weight, 10% to 40% by weight, or 10% to 30% by weight, based on the total weight of the resin composition.

[0041] (Other Components) In addition to the polyolefins, other thermoplastic resins, elastomers, and fillers described above, the resin compositions of this disclosure may also contain other components. Examples of other components include ultraviolet absorbers, stabilizers, antioxidants, plasticizers, colorants, color adjusters, flame retardants, antistatic agents, fluorescent whitening agents, matting agents, and impact strength modifiers.

[0042] The content of other components may be, for example, 0.01% to 10% by weight, 0.1% to 5% by weight, or 0.1% to 3% by weight, based on the total weight of the resin composition.

[0043] <Shape> The shape of the resin composition of this disclosure is not particularly limited and may be pellets or filaments. As pellets, for example, spherical, cylindrical, or irregularly shaped ones can be used. In general, in direct pellet type 3D printers (three-dimensional molding devices), stable molding is possible regardless of shape as long as the pellets have good transportability and heat meltability. Therefore, the resin pellets of this disclosure can adopt any shape depending on the manufacturing method and material properties.

[0044] The filament is not particularly limited, but is generally a string- or thread-like material formed in a cylindrical shape with a predetermined diameter. The diameter of the filament can be appropriately selected depending on the 3D printer model and extrusion mechanism. The cross-sectional shape of the filament is preferably circular, and high roundness is desirable. However, elliptical or irregular shapes can also be used as long as stable material feeding is possible.

[0045] Generally, the nozzle diameter of a direct pellet 3D printer is larger than that of a filament 3D printer, resulting in a larger diameter of extruded strands. Therefore, direct pellet 3D printers require time for the strands to cool immediately after printing, and the high temperature can persist for a relatively long period. In this regard, the resin pellets of this disclosure are preferable because the molten strands maintain their self-supporting properties and exhibit excellent moldability immediately after printing, making them suitable for use in direct pellet 3D printers with large nozzle diameters.

[0046] 《Method for Manufacturing Resin Compositions》 The resin compositions of this disclosure can be manufactured using conventional extrusion methods. When the resin composition is in the form of pellets, it can be obtained by mixing polypropylene, propylene-α-olefin copolymer, elastomers immiscible with polypropylene, and various other materials in predetermined proportions, melt-kneading, and granulating. For melt-kneading and granulation, for example, a single-screw extruder or a twin-screw extruder can be used, making it possible to stably produce compositions with a uniform composition that has excellent kneadability and dispersibility. The kneading conditions (screw configuration, temperature, and rotation speed, etc.) can be appropriately adjusted according to the MFR of the raw resin and the type and content of fillers.

[0047] When the resin composition is a filament, it is manufactured by melt-spinning the above-mentioned predetermined materials and then stretching them. Known melt-spinning methods can be used for melt-spinning. The same applies to stretching. For example, a method can be described that includes an extrusion step in which the above-mentioned predetermined materials are extruded as a molten strand from the die hole of a single-screw or twin-screw extruder and guided to a cooling water tank to obtain the strand, a stretching step in which the strand is stretched, and a winding step in which the stretched filament is wound up.

[0048] <Three-Dimensional Manufactured Objects> The three-dimensional manufactured objects of this disclosure can be manufactured using the three-dimensional manufacturing resin composition of this disclosure. The manufacturing method may be a direct pellet method. By manufacturing the three-dimensional manufactured objects of this disclosure using the three-dimensional manufacturing resin composition of this disclosure, resin sagging and distortion during manufacturing are suppressed, and the objects exhibit excellent impact resistance and bending strength.

[0049] The three-dimensional molded object of this disclosure preferably has a hollow structure. In this disclosure, a hollow structure refers to a structure that has a space inside the three-dimensional molded object that is not filled with material. The hollow structure is not limited to a structure that has a completely sealed space, and includes, for example, tubular or cylindrical structures as shown in Figure 1. Having a hollow structure in a three-dimensional molded object reduces warping due to molding shrinkage and allows for weight reduction. The method for forming the hollow structure is not particularly limited, but for example, a hollow structure can be formed by continuously laminating strands formed by extruding molten resin from a nozzle during three-dimensional molding. Specifically, the strands extruded from the nozzle are laminated in a closed-loop shape (a shape that is continuous and revolves around without breaks) in a plane or three-dimensional space, thereby forming a space inside the laminated strands and obtaining a three-dimensional molded object with a hollow structure (see, for example, Figure 1). Furthermore, it is preferable that the hollow structure is formed by a so-called single-stroke molding path, in which the strands are formed continuously without interruption. As described above, the resin composition of this disclosure maintains a molten state for a long time during molding due to the addition of P-αOR, and the adhesion strength between strands is improved, so that sufficient impact resistance and bending strength in the 90° direction with respect to the lamination direction can be ensured on the wall surface of the hollow structure. Therefore, even with a hollow structure that has little physical support from the inside, it is possible to provide a three-dimensional molded object with high mechanical strength.

[0050] <Method for Manufacturing Three-Dimensional Objects> The method for manufacturing three-dimensional objects according to the present disclosure can be used to manufacture objects by a method that includes a lamination step of laminating strands formed by melting the resin composition for three-dimensional molding according to the present disclosure in a screw-type extruder and extruding them from a nozzle. The method for manufacturing three-dimensional objects according to the present disclosure can provide three-dimensional objects that have excellent impact resistance and bending strength, as resin sagging and distortion during molding are suppressed by 3D printing of the resin composition for three-dimensional molding according to the present disclosure.

[0051] In a preferred embodiment, a direct pellet type 3D printer can be used in the method for manufacturing a three-dimensional object according to the disclosure. The direct pellet type 3D printer has a stage on which the three-dimensional object is formed, a screw extruder, and a moving mechanism for moving the screw extruder relative to the stage. The screw extruder has a cylinder, a heater, a screw disposed inside the cylinder, and a nozzle. The screw extruder is configured to melt and knead the resin pellets for three-dimensional molding supplied into the cylinder by heating with the heater and rotating the screw, and to transport them to the tip of the cylinder and extrude them through the nozzle. An opening is provided at the tip of the nozzle, and the diameter of the opening (nozzle diameter) is not particularly limited, but is preferably 1.0 mm or more, more preferably 2.5 mm or more, even more preferably 5.0 mm, and particularly preferably 7.5 mm or more. By setting the nozzle diameter to 1.0 mm or more, the molding speed of the three-dimensional object can be increased. The resin composition for three-dimensional molding disclosed herein maintains self-supporting properties in the molten strand immediately after molding, resulting in excellent moldability. Therefore, it is possible to achieve both high molding speed and excellent moldability.

[0052] Examples of embodiments of this disclosure will be described below with reference to examples and comparative examples, but this disclosure is not limited to the following examples and comparative examples.

[0053] Materials: Details of the various materials used in the examples and comparative examples are as follows.

[0054] <Random Polypropylene Resin (rPP)> rPP1: Prime Polypropylene (registered trademark) F730NV (manufactured by Prime Polymer Co., Ltd., MFR (230℃, 2.16 kg load): 6.2 g / 10 min)

[0055] <Blocked Polypropylene Resin (bPP)> bPP1: Prime Polypro (registered trademark) J452HP (manufactured by Prime Polymer Co., Ltd., MFR (230℃, 2.16 kg load): 4.2 g / 10 min) bPP2: Propylene polymer A (MFR: 50 g / 10 min) composed of polymers A-1 and A-2 below. Propylene polymer (A-1): 76.5 parts by weight relative to parts by weight of polymer A. MFR: 213 g / 10 min. Content of constituent units derived from propylene: 99.9 mol% (relative to A-1). Propylene-ethylene copolymer (A-2): 23.5 parts by weight relative to parts by weight of polymer A. Intrinsic viscosity [η]: 2.5 dl / g, Content of constituent units derived from ethylene: 39 mol% (relative to A-2).

[0056] <Fillers (reinforcement fibers)> Carbon fiber 1 (CF1): PYROFIL® TR066A (manufactured by Mitsubishi Chemical Corporation, carbon fiber type: PAN 24t, sizing material: epoxy-based) Glass fiber 1 (GF1): E glass fiber: chopped strand T-480 (manufactured by Nippon Electric Glass Co., Ltd., glass fiber type: fiber diameter 13 μm, Nominal LOI: 0.5%)

[0057] <Olefin-based elastomers> EBR1: Tuffmer® DF610 (manufactured by Mitsui Chemicals, ethylene-1-butene copolymer, MFR (230℃, 2.16 kg load): 2.2 g / 10 min) EBR2: Tuffmer® DF605 (manufactured by Mitsui Chemicals, ethylene-1-butene copolymer, MFR (230℃, 2.16 kg load): 0.9 g / 10 min) PBR1: Tuffmer® XM7090 (manufactured by Mitsui Chemicals, propylene-1-butene copolymer, MFR (230℃, 2.16 kg load): 7.0 g / 10 min)

[0058] <Modified Polyolefin Resin> MAH-PP1: Maleic anhydride-modified polypropylene resin (modified PP) obtained by the following synthesis method. 100 parts by weight of polypropylene (manufactured by Prime Polymer Co., Ltd., trade name J106G, MFR (230℃, 2.16 kg): 15 g / 10 min) was pre-mixed with 1 part by weight of dialkyl peroxide (manufactured by NOF Corporation, Perhexa 25B ("Perhexa" is a registered trademark of the company)) and 3 parts by weight of powdered maleic anhydride (manufactured by NOF Corporation, CRYSTAL MAN ("CRYSTAL MAN" is a registered trademark of the company)). This mixture was supplied to a 30 mmφ twin-screw extruder heated to 190℃ and melt-kneaded at 200 rpm. The resulting strand was cooled in a water bath to obtain maleic anhydride-modified polypropylene. To remove unmodified residual maleic anhydride, this maleic anhydride-modified polypropylene was vacuum-dried at 40℃ for 2 hours. The maleic acid content of the obtained maleic anhydride-modified polypropylene was 2.5% by weight, and the MFR (230°C, 2.16 kg) was 800 g / 10 min. MAH-PP2: Maleic anhydride-modified polypropylene (manufactured by Mitsui Chemicals, Inc., product name "Admer AT2606", MFR: 220 g / 10 min (190°C, 2.16 kg load), density 900 kg / m³) ３ )

[0059] <Example of Resin Pellet Production> <Production of Compounds and Pellet> The above materials were melt-kneaded and granulated using the following compound granulation apparatus and under the following conditions, with the compositions shown in Table 1 (units are in weight %), to obtain each type of pellet.

[0060] <Compound Granulation Equipment and Conditions> Equipment: Co-rotating twin-screw extruder HK-25D (manufactured by Parker Corporation) Barrel diameter: 30 mm Screw process length (L / D): 63 Cylinder set temperature: 200°C Screw rotation speed: 150 rpm Pellet length: 3 mm

[0061] <Measurement and Evaluation Method> <Evaluation of Formability and Appearance of the Manufactured Object> The following direct pellet 3D printer was used. Using the screw extruder equipped with the direct pellet 3D printer, pellets were melted and extruded to produce a three-dimensional object with a hollow structure as shown in Figure 1, under the following manufacturing conditions. The angle of the obliquely manufactured parts was 45°. The formability and appearance of the manufactured object were evaluated.

[0062] (Direct pellet 3D printer and printing conditions) Equipment: Direct pellet large 3D printer EXF-12 (manufactured by ExtraBold Co., Ltd.) Nozzle diameter: 8 mm Nozzle temperature: 220°C Printing speed: 394 mm / min Layer thickness: 4 mm

[0063] <Impact Strength (3D Printer Test Specimen (90°))> The following direct pellet 3D printer was used. Using the screw extruder equipped with the direct pellet 3D printer, pellets were melted and extruded to create a three-dimensional object with a hollow structure as shown in Figure 2. A sample for impact strength measurement was prepared by cutting out a shape with a V-shaped notch in accordance with JIS K7111 from the wall surface of the obtained object. The longitudinal direction of the impact strength measurement sample was oriented in the layering direction. That is, the impact was applied in a direction 90° to the layering direction. Using the obtained impact strength measurement sample, the impact resistance value (kJ / m) was measured in accordance with JIS K7111 at a test temperature of 23°C and a hammer capacity of 7.5 J. ２ ) was sought.

[0064] (Direct pellet 3D printer and printing conditions) Equipment: Direct pellet large 3D printer EXF-12 (manufactured by ExtraBold Co., Ltd.) Nozzle diameter: 8 mm Nozzle temperature: 220°C Printing speed: 1200 mm / min Extrusion width: 13.5 mm Layer thickness: 4 mm

[0065] <Bending Strength (3D Printed Test Specimen (90°))> Similar to the impact strength measurement sample, a three-dimensional object with a hollow structure was fabricated using a direct pellet 3D printer. A sample for bending strength measurement was created by cutting out a strip shape in accordance with JIS K7111 from the wall surface of the obtained object. The bending strength measurement sample was oriented so that the longitudinal direction was the layering direction. Using the obtained bending strength measurement sample, the bending strength (MPa) was determined at a test temperature of 23°C in accordance with JIS K7111.

[0066] <Impact Strength (Injection Molded Test Specimen)> Dumbbell-shaped test specimens were created from pellets using the following injection molding machine. The obtained test specimens were processed to have a V-shaped notch in accordance with JIS K7111.1eA, and the impact resistance value (kJ / m) was measured at 23°C with a hammer capacity of 7.5 J in accordance with the JIS K7111.1eA standard. ２ ) was sought.

[0067] (Charpy impact test) Equipment: Impact testing machine with constant temperature chamber DG-UB (Toyo Seiki Seisakusho)

[0068] (Injection Molding Machine) Equipment: Injection molding machine J100 ADS 180U (manufactured by Japan Steel Works) Barrel setting temperature (The temperature at the nozzle tip is set to NH2 and NH1, and the temperature is set in stages from H4 to H1 as it moves towards the hopper. The temperature directly below the hopper is set to HP.): NH2 / NH1 / H4 / H3 / H2 / H1 / HP = 230 / 240 / 250 / 250 / 240 / 230 / 80℃ Mold temperature: 60℃

[0069] <Bending Strength (Injection Molded Test Specimen)> Similar to the injection molded test specimen, a dumbbell-shaped test specimen was prepared using an injection molding machine. The obtained test specimen was processed into a strip shape in accordance with JIS K7111, and the bending strength (MPa) was determined at a test temperature of 23°C in accordance with JIS K7111.

[0070]

[0071] Regarding moldability and the appearance of the molded objects, no deformation was observed in any of Examples 1-5 or Comparative Examples 1-4, and no melt fractures were observed on the surface of the molded objects. Regarding impact resistance and flexural strength, Examples 1-5, which contained polypropylene, propylene-α-olefin copolymer, and an elastomer incompatible with polypropylene, were superior to Comparative Examples 1-4. Specifically, Examples 1-4, which contained block polypropylene, propylene-α-olefin copolymer, and an elastomer incompatible with polypropylene, showed significantly improved impact resistance compared to Comparative Example 1, which did not contain an elastomer incompatible with polypropylene. Furthermore, compared to Comparative Examples 2 and 3, which did not contain propylene-α-olefin copolymer, the impact strength ratio and flexural strength ratio were significantly improved, resulting in excellent impact resistance and flexural strength as three-dimensional molded objects. Furthermore, Example 5, which contains random polypropylene, a propylene-α-olefin copolymer, and an elastomer incompatible with polypropylene, showed a significant improvement in impact strength ratio and flexural strength ratio compared to Comparative Example 4, which does not contain a propylene-α-olefin copolymer, exhibiting excellent impact resistance and flexural strength as a three-dimensionally fabricated object.

Claims

1. A resin composition for three-dimensional molding, wherein the resin composition contains polypropylene, a propylene-α-olefin copolymer, and an elastomer incompatible with the polypropylene, and the weight % of the polypropylene contained in the resin composition is W ＰＰ , the weight % of the propylene-α-olefin copolymer is W ＰＯＲ When that happens, W ＰＰ >W ＰＯＲ A resin composition that satisfies the requirements.

2. The resin composition according to claim 1, wherein the polypropylene includes block copolymerized polypropylene.

3. The resin composition according to claim 1 or 2, wherein the propylene-α-olefin copolymer comprises a propylene-1-butene copolymer.

4. The resin composition according to claim 1 or 2, wherein the immiscible elastomer comprises an ethylene-α-olefin copolymer.

5. The resin composition according to claim 4, wherein the ethylene-α-olefin copolymer comprises an ethylene-1-butene copolymer.

6. The resin composition according to claim 3, wherein the immiscible elastomer comprises an ethylene-1-butene copolymer.

7. The resin composition according to claim 1 or 2, further comprising reinforcing fibers.

8. W ＰＰ ≤ 2.0 × W ＰＯＲ A resin composition according to claim 1 or 2 that satisfies the requirements.

9. The resin composition according to claim 1 or 2, wherein the resin composition contains 10% by weight or more and 90% by weight or less of the polypropylene, based on the total weight of the resin composition.

10. The resin composition according to claim 1 or 2, wherein the resin composition contains 5% by weight or more and 50% by weight or less of the propylene-α-olefin copolymer, based on the total weight of the resin composition.

11. A three-dimensional object formed using the resin composition described in claim 1 or 2.

12. The three-dimensional object according to claim 11, having a hollow structure.

13. A method for manufacturing a three-dimensional object, comprising a lamination step of laminating strands formed by melting the resin composition according to claim 1 or 2 and extruding them from a nozzle.

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