Linear resin molding

Abstract

To provide a molded resin strand capable of preventing moisture absorption of a three-dimensionally molded shape-memory polymer, for example, capable of maintaining a performance even in a wet environment.SOLUTION: There is provided a molded resin strand comprising an outer layer made of a water barrier material on an outside of an inner layer material containing a shape-memory polymer. The water barrier material is, for example, a thermoplastic resin having low water absorption property or a thermoplastic resin having water vapor barrier property. The molded resin strand is used in a thermal fusion lamination-type 3D printer. A 3D molded article which is molded using the molded resin strand containing the shape-memory polymer fixes a deformed shape by applying deformation thereto at a temperature of equal to or greater than a glass-transition temperature (Tg) of the shape-memory polymer and less than a melting temperature thereof or less than a decomposition temperature thereof, and cooling to the glass-transition temperature thereof or lower in a state where the shape is sustained; and recovers an original molded shape by heating to the temperature of the glass-transition temperature thereof or higher and less than a melting temperature thereof or less than a decomposition temperature thereof.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a filamentary resin molding, and more particularly to a filamentary resin molding used as a raw material in modeling devices for constructing three-dimensional objects such as so-called 3D printers. [Background technology]

[0002] As a method for forming three-dimensional objects, so-called 3D printers have been attracting attention, and it is becoming possible to easily create three-dimensional objects with complex shapes that were previously difficult to realize. By using a 3D printer, it is possible to process shapes that are impossible to realize by normal methods by stacking any material, such as resin or metal.

[0003] There are several known types of 3D printers, among which the type that extrudes resin strands (linear resin moldings) and stacks them (fused deposition modeling) is advantageous in terms of cost and is therefore being developed in various fields (see, for example, Patent Document 1 and Patent Document 2).

[0004] For example, in the additive manufacturing system of Patent Document 1, a filament, which is a modeling material, is supplied to an extrusion head, the filament is melted by a liquefier mounted on the extrusion head, and the molten filament is extruded onto a base through a nozzle. The extrusion head and the base move relative to each other to form a 3D model, and a large number of linear and layered materials are stacked to produce the 3D model.

[0005] US Patent No. 5,399,933 discloses a method of building a 3D object that includes delivering a modified ABS material to an extrusion head of an extrusion layer-by-layer deposition system, melting the delivered modified ABS material in the extrusion head under conditions that improve the response time of the extrusion head, and depositing the molten thermoplastic material layer-by-layer to form the 3D object.

[0006] In this type of method, the basic idea is to melt and deposit a resin material, and a resin strand (a linear resin molding) is used as a raw material. Patent Documents 3 and 4 disclose the resin strand used as the raw material and a method of supplying the resin strand.

[0007] US Patent No. 5,399,633 discloses a composition for creating three-dimensional objects, which is fed as a flexible filament to an extrusion head in an extrusion machine that produces the model. The filament is melted in a liquifier carried by the extrusion head. The liquifier heats the filament to a temperature slightly above its freezing point, causing it to become molten. The molten material is extruded through an orifice in the liquifier onto a base.

[0008] Patent Document 4 discloses a filament cassette and a filament cassette receiver for supplying a filament in a three-dimensional deposition modeling machine. Patent Document 4 provides a method for engaging and disengaging a filament from the modeling machine in a simple manner, and can be realized in a manner that protects the filament from moisture in the environment. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Special Publication No. 2009-500194 [Patent Document 2] Special Publication No. 2010-521339 [Patent Document 3] Patent No. 5039549 [Patent Document 4] Patent No. 4107960 Summary of the Invention [Problem to be solved by the invention]

[0010] In the above-mentioned 3D printer, a shape memory polymer can also be used as the resin material for modeling. A shape memory polymer is a resin that can be used to change between a molded shape and a deformed shape by controlling the temperature with heat. A molded body of a shape memory polymer is deformed at a temperature equal to or higher than the glass transition temperature (Tg) of the shape memory polymer and lower than the melting temperature or decomposition temperature, and the deformed shape is fixed by cooling to the glass transition temperature or lower while maintaining the shape, and the original molded shape is restored by heating to a temperature equal to or higher than the glass transition temperature and lower than the melting temperature or decomposition temperature.

[0011] However, it has been found that when such shape-memory polymers are used as filaments in 3D printers, their performance decreases due to moisture absorption. Due to their shape change and memory properties, shape-memory polymers are expected to be used, for example, as various supports and orthodontic appliances. However, when used in a humid environment (for example, orthodontic supports in the mouth), it has been found that their performance decreases if they absorb moisture above a certain level, and improving this has become a challenge.

[0012] For example, Patent Document 4 attempts to protect the filament from moisture in the environment, but gives no consideration to moisture absorption by the molded object.

[0013] The present invention has been proposed in consideration of the above-mentioned conventional situation, and aims to provide a linear resin molding that can prevent moisture absorption in a 3D molded object made from a shape memory polymer and can maintain its performance, for example, even in a humid environment. [Means for solving the problem]

[0014] In order to achieve the above object, the linear resin molding of the present invention comprises: A filamentary resin molded body used in a fused deposition model 3D printer, On the outside of the inner layer containing shape memory polymer It has an outer layer made of ethylene-vinyl alcohol copolymer. It is characterized by: Alternatively, the present invention is characterized in that an outer layer made of a water vapor barrier composition containing an inorganic layered compound and a resin is provided on the outside of an inner layer material containing a shape memory polymer.

[0015] By covering the periphery of the inner layer material made of a shape memory polymer with an outer layer made of a water barrier material, the inner layer material made of a shape memory polymer is prevented from absorbing moisture, and deterioration of the performance of the shape memory polymer is suppressed. Effect of the Invention

[0016] According to the filamentary resin molding of the present invention, when a shape memory polymer is three-dimensionally molded, the molded product can be prevented from absorbing moisture, and it is possible to maintain performance even in a humid environment, for example. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of a 3D printer. [Diagram 2] FIG. 2 is a schematic perspective view showing an example of a linear resin molding. [Diagram 3] 3 is a cross-sectional view of the linear resin molding shown in FIG. 2. [Figure 4] FIG. 2 is a diagram showing an example of a production line for a filamentary resin molding. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Below, an embodiment of a linear resin molding to which the present invention is applied will be described with reference to the drawings. However, before describing the linear resin molding of this embodiment, a 3D printer in which the linear resin molding is used will first be described.

[0019] The basic mechanism of a 3D printer is to create a solid object, i.e., a 3D (three-dimensional) object, by stacking cross-sectional shapes using 3D data created by a computer as a design drawing. Methods for this include, for example, an inkjet method in which liquid resin is irradiated with ultraviolet light or the like to gradually harden it, a powder adhesion method in which an adhesive is sprayed onto powdered resin, and a fused lamination method in which resin melted by heat is gradually stacked. The linear resin molded body according to this embodiment is used in a fused lamination method 3D printer, and is supplied to the 3D printer in a state wound on a reel, for example.

[0020] 1 is a diagram showing an example of a 3D printer. The main components of the 3D printer of this example are a modeling head 2 driven in three dimensions by a drive mechanism 1, and a cartridge 4 that supplies a filament resin molding (filament) 10 made of a resin material to the modeling head 2. The filament resin molding 10 wound around the cartridge 4 is guided to the modeling head 2, heated and melted, and extruded from a nozzle 2A of the modeling head 2. The filament resin molding 10 is then piled up and cooled to form a three-dimensional model M on a base 5.

[0021] 2 and 3 show a linear resin molding 10 of this embodiment. The linear resin molding 10 of this embodiment has an inner layer material 11 covered with an outer layer 12, and is a two-layer linear resin molding 10.

[0022] Regarding the constituent materials of each layer that makes up the linear resin molding 10, the inner layer material 11 of the linear resin molding 10 in this embodiment uses a shape memory polymer because it enables the formation of a 3D model that can easily change shape by heating it above its glass transition temperature after molding, retain the shape by cooling, and then return to its original shape by reheating it above its glass transition temperature.

[0023] A shape memory polymer is a material having shape memory properties. The shape memory properties are properties that return to the original shape by elasticity when heated to a predetermined recovery temperature or higher. The recovery temperature is a temperature determined for each material, and is, for example, 0 to 100°C, preferably 25 to 80°C, specifically, for example, 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100°C, and may be within a range between any two of the numerical values ​​exemplified here.

[0024] The recovery temperature of a shape memory polymer is the glass transition temperature (Tg). When an external force is applied to the polymer at a temperature equal to or higher than the Tg to give it a secondary shape, and the polymer is cooled to a temperature below the Tg while maintaining the external force, the secondary shape is fixed. At temperatures below the Tg, the polymer does not return to its original shape even when the external force is removed. On the other hand, when a shape memory polymer to which a secondary shape has been given is heated to a temperature equal to or higher than the Tg and is placed in a state where no external force is applied, the polymer returns to its original shape due to its elasticity. The original shape can be set, for example, by melting the shape memory polymer and molding it into a desired shape. Examples of shape memory polymers include polymers having rubber elasticity, such as polynorbornene, trans-polyisoprene, styrene-butadiene copolymer, and polyurethane.

[0025] The blending amount of the shape memory polymer in the inner layer material 11 may be 100% by mass, or other materials may be blended in consideration of moldability, etc. When other materials are blended, the blending amount is preferably 40% to 89% by mass, and more preferably 60% to 79% by mass.

[0026] In the linear resin molding 10, if the shape memory polymer is used alone for the inner layer material 11, the shape is easily distorted due to the influence of heat during deposition, and the molding speed may not be increased. Therefore, an inorganic filler may be blended into the inner layer material 11 for the purpose of improving heat dissipation.

[0027] As the inorganic filler, a fibrous or powdery one can be used, and the material can be any, but one with high thermal conductivity is preferable. Examples include carbon fiber, glass fiber, talc, nanoclay, calcium carbonate, magnesium carbonate, etc., and carbon fiber and glass fiber with good thermal conductivity are preferable. In addition, when a fibrous inorganic filler is used, there is also an advantage that the shape recovery after molding is also high.

[0028] The amount of inorganic filler added may be set according to the required performance (heat dissipation, etc.), but is preferably 3% by mass to 30% by mass, and more preferably 5% by mass to 20% by mass. If the amount of inorganic filler is less than 3% by mass, the effect of adding the inorganic filler may be insufficient. Conversely, if the amount of inorganic filler is too high, exceeding 30% by mass, the proportion of shape memory polymer becomes relatively too low, which may cause delamination of the molded object and make molding difficult.

[0029] As described above, when the inner layer material 11 of the linear resin molding 10 contains a shape memory polymer, the deterioration of performance due to moisture absorption becomes a problem. Therefore, in the linear resin molding 10 of the present embodiment, the outer layer 12 is formed by covering the inner layer material 11.

[0030] The outer layer 12 may be formed from a water barrier material that prevents the intrusion of water molecules. For example, it is possible to form the outer layer 12 having water vapor barrier properties as an inorganic coating by vapor-depositing an inorganic material. However, taking into consideration the formability and fusion properties of the filamentary resin molding 10, it is preferable that the outer layer 12 be a thermoplastic resin with water barrier properties that prevents the intrusion of water molecules.

[0031] Here, the thermoplastic resin with water barrier properties that prevents the intrusion of water molecules is a material with low water absorption or a material with water vapor barrier properties, and for example, a material with low water absorption is a material with a water absorption rate of 0.1% or less, preferably 0.05% or less, measured according to Japanese Industrial Standards (JIS) K 7209 "Determination of Water Absorption Rate of Plastics". Specific examples include polyethylene, polypropylene, liquid crystal polymer, polyphenylene sulfide, fluororesin, etc.

[0032] As the thermoplastic resin having water vapor barrier properties, for example, an ethylene-vinyl alcohol copolymer resin is preferably used. The ethylene-vinyl alcohol copolymer resin is made of a saponified ethylene-vinyl acetate copolymer, and any known resin can be used. In the ethylene-vinyl alcohol copolymer resin, the ethylene content is preferably 20 to 70 mol %, and the saponification degree of vinyl acetate is preferably 95 mol % or more, and more preferably the ethylene content is 25 to 50 mol %, and the saponification degree of vinyl acetate is 98 mol % or more. If the saponification degree is low, the water vapor barrier properties may be reduced.

[0033] Alternatively, it is also possible to use a water vapor barrier composition containing inorganic particles and a resin. When the water vapor barrier composition is cured by heat treatment, for example by contact with a thermosetting resin, the inorganic particles are regularly arranged, making it difficult for gas to pass through, and the water vapor barrier property is exhibited by the so-called labyrinth effect.

[0034] Therefore, the inorganic particles are preferably so-called inorganic layered compounds. Inorganic layered compounds are compounds in which unit crystal layers are stacked on top of each other to form a layered structure, and specific examples thereof include graphite, phosphate derivative compounds (zirconium phosphate compounds, etc.), chalcogenides, hydrotalcite compounds, lithium aluminum composite hydroxides, clay minerals, etc. Examples of clay minerals include kaolinite-serpentine clay minerals such as kaolinite, talc-pyrophyllite clay minerals such as talc, smectite clay minerals such as montmorillonite, vermiculite clay minerals, mica clay minerals such as tetrasilylic mica, brittle mica clay minerals such as xanthophyllite, and chlorite clay minerals such as clinochlore.

[0035] Examples of resins include polyvinyl alcohol (PVA), ethylene-vinyl alcohol copolymer (EVOH), polyvinylidene chloride, polyacrylonitrile, polysaccharides, polyacrylic acid and its esters, polymethacrylic acid and its esters, amide resins, imide resins, ester resins, resins having two or more types of functional groups in one molecule, urethane resins, epoxy resins, phenolic resins, and melamine resins.

[0036] As the water vapor barrier composition, commercially available products can be used, for example, EXCEVIER NOH1200 (trade name) and EXCEVIER NOH2200 (trade name) manufactured by Sumitomo Chemical Co., Ltd.

[0037] The outer layer 12 may be formed by any method that can form a coating by covering the inner layer material 11. For example, the inner layer material 11 and the outer layer 12 may be formed simultaneously by co-extrusion. Alternatively, they may be formed by methods such as dipping or coating.

[0038] The thickness of the outer layer 12 is also arbitrary, but in order to obtain a sufficient moisture absorption prevention effect and not to adversely affect the shape memory property, it is preferable that the thickness is about several μm to several tens of μm.

[0039] Furthermore, when forming the outer layer 12 as described above, if there is a concern that the inner layer material 11 and the outer layer 12 may peel off from each other, it is also possible to form an adhesive layer between the inner layer material 11 and the outer layer 12. In this case, the linear resin molding 10 has a three-layer structure.

[0040] In addition to the above-mentioned materials, various additives such as colorants can be added to each layer (the inner layer material 11 and the outer layer 12) of the filamentary resin molding 10 configured as above, depending on the specifications. The number of layers of the filamentary resin molding 10 is not limited to two or three layers, and the number of layers can be further increased as necessary. The outer diameter of the filamentary resin molding 10 can also be appropriately set depending on the required specifications, and is, for example, a filament with a diameter of about 1.75 mm. Alternatively, in a structure made of the filamentary resin molding 10, the filamentary resin molding 10 has a flattened shape, and is a filament with a wire diameter of 0.4 mm and a short diameter of 0.2 mm.

[0041] Next, an example of a method (production line) for producing a filamentary resin molding will be described. As shown in Fig. 4, the production line 30 for the filamentary resin molding 10 includes an extruder 31, a die 32, a sizing device 33, a water tank 37, a fixed roller 41, an outer diameter measuring device 42, and a winding device 43.

[0042] The extruder 31 melts and kneads the raw material resin composition and continuously supplies it to the die 32, and is configured to include, for example, a cylinder with a built-in screw, a hopper for introducing raw materials, an injection nozzle, etc. The raw material resin composition introduced from the hopper for introducing raw materials is melted and kneaded by the screw in the cylinder, and is injected into the die 32 from the injection nozzle.

[0043] The die 32 is for extruding the molten resin from the extruder 31 in the horizontal direction, and the molten resin extruded from here is cooled to become the filamentary resin molding 10. The raw material resin composition is the above-mentioned shape memory polymer and a thermoplastic resin having a barrier property against water molecules, and these are co-extruded so that the outer side becomes a layer of the water-barrier resin.

[0044] The water tank 37 is formed in a long box shape along the conveying direction of the filamentary resin moldings 10 extruded from the extruder 31. The filamentary resin moldings 10 are introduced into the water tank 37 from the wall at one end thereof and discharged from the wall at the other end thereof. The water tank 37 stores water 37a in which the filamentary resin moldings 10 are immersed and used to cool the filamentary resin moldings 10.

[0045] The sizing device 33 is arranged inside the wall at one end of the water tank 37, and has the function of making the cross-section of the filamentary resin molding 10 sent from the extruder 31 into the water tank 37 a perfect circle and of uniforming the outer diameter dimension of the filamentary resin molding 10 to a predetermined dimension.

[0046] The fixed rollers 41 stabilize the posture of the linear resin molding 10 in the water tank 37 after passing through the sizing device 33, and transport the linear resin molding 10 towards the winding device 43 side.

[0047] The outer diameter measuring device 42 measures the outer diameter of the filamentary resin molding 10 cooled in the water tank 37. The winding device 43 includes a pair of upper and lower winding rollers 43a that sandwich and transport the filamentary resin molding 10 that has passed through the outer diameter measuring device 42 downstream, and a bobbin winding machine 43b that is disposed downstream of the winding rollers 43a and has a winding shaft 43c that winds up the filamentary resin molding 10.

[0048] The manufacturing method of the linear resin molding 10 includes an extrusion step, a sizing step, a cooling step, a dimension measuring step, and a winding step. In the extrusion step, resin pellets fed from a hopper 31a are melted in an extruder 31, and the molten resin is extruded from a die 32. The extruded linear resin molding 10 has an outer diameter D1.

[0049] In the sizing process, the linear resin molding 10 travels along a conveying passage and is formed into a uniform outer diameter D2 that matches the inner diameter of the conveying passage. In the cooling process, the linear resin molding 10 passes through a water tank 37 and is cooled, thereby reducing the outer diameter of the linear resin molding 10.

[0050] In the dimension measurement process, the outer diameter of the filamentary resin molding 10 is measured, and it is determined whether the measured value is an appropriate size. If the outer diameter of the filamentary resin molding 10 is out of specification, each manufacturing condition is reviewed so that the outer diameter is within specification. In the winding process, if the outer diameter of the filamentary resin molding 10 is within specification, it is sent to the bobbin winder 43b by the winding roller 43a of the winding device 43, and the continuous filamentary resin molding 10 is wound around the winding shaft 43c. When a predetermined length of the filamentary resin molding 10 has been wound around the winding shaft 43c, a new filamentary resin molding 10 is wound around the winding shaft 43c.

[0051] As described above, by forming the outer layer 12 having water barrier properties on the outside of the inner layer material 11 made of a shape memory polymer, deterioration of performance due to moisture absorption can be reliably suppressed.

[0052] In addition, by filling the inner layer material 11 with an inorganic filler, it is possible to provide a filamentary resin molding having a shape memory property that can provide a high rigidity to the molded object and further improve the restoring force. For example, when a filament using a conventional shape memory polymer is used to mold a 3D model using a 3D printer, it was difficult to mold the model depending on the shape of the model, but a filament containing glass fiber or carbon fiber has improved moldability and can be molded without any problems.

[0053] Furthermore, conventional shape memory polymers have low rigidity and limited applications, but by using filaments containing glass fiber or carbon fiber, it is possible to provide high strength and high recovery power, thereby greatly improving functionality. Therefore, by blending inorganic fillers with shape memory polymers, it is possible to manufacture linear resin molded bodies with various functions, making it possible to model with more functionality. That is, the structure formed by molding the linear resin molded body of this embodiment with a 3D printer using a fused lamination method is less susceptible to performance degradation due to moisture absorption, and can be used, for example, for orthodontic appliances.

[0054] The above describes an embodiment of the present invention, but it goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention. EXAMPLES

[0055] (Preparation of linear resin molded body) Example 1 A polyurethane shape-memory polymer (MM-5520, manufactured by SMP Technology) was used as the raw material, which was melt-kneaded in an extruder, fed to a die core, and drawn out from a die attached to the die core. At this time, an ethylene-vinyl alcohol copolymer was co-extruded to form a filamentary resin molding with the polyurethane shape-memory polymer as the inner layer material and polyethylene as the outer layer.

[0056] After the wire diameter and linearity were adjusted to a certain extent using a die to form a filamentary resin molding, a sizing unit was provided at the entrance of a water tank for cooling and solidifying, and the final cross-sectional shape (wire diameter and linearity) of the filamentary resin molding was adjusted in this sizing unit. After the shape was formed in the sizing unit, the filamentary resin molding was cooled and solidified in the water tank, and then wound up by a winding machine. Furthermore, the filamentary resin molding sent out from the winding machine was wound up on a bobbin.

[0057] Example 2 A filamentous resin molding was produced in the same manner as in Example 1, except that an ethylene-vinyl alcohol copolymer was used as the outer layer instead of polyethylene.

[0058] Comparative Example 1 A single-layer filamentary resin molding was produced using only a polyurethane-based shape memory polymer (manufactured by SMP Technology, product name MM-5520) as a raw material.

[0059] Example 3 A water vapor barrier composition (manufactured by Sumitomo Chemical Co., Ltd., product name EXCEVIER NOH1200) was applied to the outer peripheral surface of the single-layer filamentary resin molding produced in Comparative Example 1 to form an outer layer, thereby obtaining a two-layer filamentary resin molding.

[0060] (Confirmation of effectiveness) The filamentous resin molded body was used to print a 3D model using a 3D printer (manufactured by Bonsai Lab, product name BS-01), and the restoring force of the model before and after storage in a humid environment was evaluated by measuring the rigidity using a tensile test. The model was printed at 215°C.

[0061] The strength of the restoring force was measured using a universal testing machine with a thermostatic chamber (Universal testing machine: Shimadzu Corporation, product name AGS-X 10kN, thermostatic chamber: Shimadzu Corporation, product name TCRIA-200P) using a 3D printer to create a model with a length of 75 mm, and the following procedure. That is, first, the model was clamped with a chuck distance of 50 mm in an atmosphere of 75 ° C in the thermostatic chamber, and then the crosshead was moved to pull it 5 mm. After that, the temperature in the thermostatic chamber was raised to 35 ° C, the crosshead was lowered until the load was zero, and the force applied to the universal testing machine when the temperature in the thermostatic chamber was raised to 75 ° C again was measured as the restoring force.

[0062] As a result, in Examples 1 to 3, which had a water-barrier outer layer, the restoring force hardly changed before and after storage in a humid environment, but in Comparative Example 1, which had a single layer of shape-memory polymer, a clear decrease in performance (decrease in restoring force) was observed after storage in a humid environment. [Explanation of symbols]

[0063] 1 Drive mechanism 2 Modeling head 4 Cartridge 5 Base 10. Linear resin molding 11 Inner layer material 12 Outer layer 30 Production Lines 31 Extruder 32 Mold 33 Sizing device 37 Aquarium 42 External diameter measuring device 43 Winding device

Claims

1. A filamentary resin molded body used in a fused deposition model 3D printer, The inner layer material includes a shape memory polymer, and an outer layer is formed of a water vapor barrier composition containing an inorganic layered compound and a resin on the outer side of the inner layer material. the outer layer is formed of an inorganic layered compound regularly arranged by contacting and curing a thermosetting resin; The linear resin molding further comprises an adhesive layer between the inner layer material and the outer layer.

2. 2. The linear resin molding according to claim 1, wherein the outer layer is formed by coating.

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