JP6957377B2 - Modeling materials for 3D printers, how to use them, and modeling methods - Google Patents

Description

The present invention relates to a modeling material for a 3D printer, a method of using the same, and a modeling method.

In recent years, additional manufacturing technology has become widespread as one of the technologies for producing a modeled product having a complicated structure.

Addition manufacturing technology represented by 3D printers is a method that does not use a mold, which was indispensable in conventional injection molding, so there is a merit that it can be prototyped in a short period of time. It is becoming more and more used. In addition, there is an increasing need for application not only to prototypes but also to direct production of small-lot, high-mix products.

There are several modeling methods for additional manufacturing technology, but in the modeling of final products used for industrial applications, a 3D printer that employs a powder sintering method that melts powdered resin with a laser or heat to create a model. However, it is being put to practical use in recent years.
On the other hand, many low-priced 3D printers employ the additive manufacturing technology of the Fused Deposition Modeling method. In the Fused Deposition Modeling method, a filamentous resin material is extruded by a pulley in the modeling head, and the filamentous resin material is melted by a heater at the end, and the extruded resin is pressed against the modeling table. It is a technology.

Polylactic acid is widely known as a resin constituting a filament that can be used in the Fused Deposition Modeling method (Patent Document 1). Polylactic acid has a melting point of about 170 ° C. and can be melted at a relatively low temperature among plastics, and is therefore suitable for home 3D printers.

Japanese Unexamined Patent Publication No. 2016-94679

However, since polylactic acid is a biodegradable resin, it is easily decomposed or deteriorated, and its mechanical strength is not sufficient. Therefore, it is expected that engineering plastic materials such as polyacetal will appear as materials for the Fused Deposition Modeling method.

By the way, in the Fused Deposition Modeling method, in general, heat shrinkage occurs in each laminated layer in the modeling process, so that the modeled product is warped and peeled or cracked between the laminated layers, so that the desired shape can be obtained. There is a problem that it is difficult to model. Further, also in the powder melting method, the warp of the modeled product at the time of modeling or cooling is a big problem.

Under these facts, especially when polyacetal is used as a material for a 3D printer, the above-mentioned problems are remarkably shown, and a material having a level that can withstand practical use has not yet been found. Further, in the conventional techniques including Patent Document 1, the use of polyacetal in the Fused Deposition Modeling method has not been sufficiently studied, and it has been difficult to suppress warpage during modeling and perform precise modeling. ..

Therefore, an object to be solved by the present invention is to provide a modeling material containing polyacetal, which can precisely model a complicated modeled product by a 3D printer. Further, an object to be solved by the present invention is to provide a method of using the above-mentioned modeling material and a modeling method capable of precisely modeling a complicated modeled product.

As a result of intensive research to solve the above problems, the present inventors have found that a complex model can be precisely modeled by a 3D printer by using a material containing polyacetal that satisfies a specific requirement. The heading, the present invention was completed.

That is, the present invention is as follows.
[1]
It is a modeling material for a 3D printer containing polyacetal, and the modeling material is
The content of the polyacetal is 45% by mass or more, and the content is 45% by mass or more.
A modeling material for a 3D printer, characterized in that the shrinkage degree obtained as the ratio of the specific volume at 50 ° C. to the specific volume at 200 ° C. is 0.875 or more.
[2]
Further contains an inorganic filler,
The modeling material according to [1], wherein the content of the inorganic filler is 5 to 120 parts by mass with respect to 100 parts by mass of the polyacetal.
[3]
Further contains polylactic acid resin,
The modeling material according to [1] or [2], wherein the content of the polylactic acid resin is 5 to 120 parts by mass with respect to 100 parts by mass of the polyacetal.
[4]
The modeling material according to any one of [1] to [3], wherein the content of the polyacetal is 50% by volume or more.
[5]
The modeling material according to any one of [1] to [4], wherein the crystallization rate is 35 seconds or more.
[6]
The modeling material according to any one of [1] to [5], wherein the melting point peak measured by differential scanning calorimetry (DSC) shows a single peak.
[7]
The modeling material according to any one of [2] to [6], wherein the inorganic filler is at least one selected from hydroxides, oxides, silicates, carbonates and carbon-based substances.
[8]
The modeling material according to any one of [2] to [7], wherein the inorganic filler is isotropic.
[9]
The modeling material according to any one of [2] to [8], wherein the inorganic filler has an average particle size of 50 nm or more and 500 nm or less.
[10]
The modeling material according to any one of [1] to [9], which is used for a powder melting method 3D printer.
[11]
The modeling material according to any one of [1] to [9], which is used for a 3D printer of the Fused Deposition Modeling method.
[12]
The modeling material according to any one of [1] to [9], which is monofilament-like and has a roundness ratio of 1.05 or less represented by a ratio of a major axis to a minor axis.
[13]
[12] A method of modeling with a 3D printer of the Fused Deposition Modeling method, which comprises using the modeling material described in [12].
[14]
The method for using a modeling material according to [12], which is characterized by being used in a 3D printer of the Fused Deposition Modeling method.

According to the present invention, it is possible to provide a modeling material containing polyacetal, which can precisely model a complicated modeled product by a 3D printer. Further, according to the present invention, it is possible to provide a method of using the above-mentioned modeling material and a modeling method capable of precisely modeling a complicated modeled product.

Hereinafter, a mode for carrying out the present invention (hereinafter referred to as the present embodiment) will be described in detail. The present invention is not limited to the following embodiments, and can be variously modified and implemented within the scope of the gist thereof.

(Modeling material for 3D printers)
The modeling material for a 3D printer in the present embodiment (hereinafter, may be simply referred to as “modeling material”) contains at least polyacetal as a resin, and the modeling material has a polyacetal content of 45% by mass or more. It is characterized in that the degree of shrinkage obtained as the ratio of the specific volume at 50 ° C. to the specific volume at 200 ° C. is 0.875 or more. In addition, the modeling material in the present embodiment may further contain a polylactic acid resin, an inorganic filler, other components, and the like, if necessary.

<Degree of contraction>
As described above, the modeling material in the present embodiment has a shrinkage degree obtained as the ratio of the specific volume at 50 ° C. ([specific volume at 50 ° C.] / [specific volume at 200 ° C.]) to the specific volume at 200 ° C. It is 875 or more.
Since polyacetal is a crystalline resin, it has high shrinkage, and it has been difficult to form it by the Fused Deposition Modeling method. Under such circumstances, the present inventors measured the PVT curve of the material and focused on it, and found that the ratio of the specific volume at 200 ° C. for melting to the specific volume at 50 ° C. for solidification was calculated. If the value is 0.875 or more, even if the model is formed by the fused deposition modeling method using a modeling material containing polyacetal, the warp and delamination of the modeled product are suppressed, and precise modeling is possible. I found it.

Further, the shrinkage degree of the modeling material is preferably 0.877 or more, more preferably 0.879 or more, from the viewpoint of enabling more precise modeling. The upper limit of the shrinkage of the modeling material is not particularly limited, but is 0.950 or less from a practical point of view.
In this embodiment, the degree of shrinkage is determined under a pressure of 0.1 MPa.

<Crystallization rate>
The modeling material in this embodiment preferably has a crystallization rate of 35 seconds or more. When the crystallization rate is 35 seconds or more, warpage and delamination during molding can be suppressed more effectively. From the same viewpoint, the crystallization rate of the modeling material is more preferably 38 seconds or more, and further preferably 40 seconds or more.
Here, the crystallization rate can be measured by differential scanning calorimetry (DSC), for example, using "DSC-2C" manufactured by Parki Elmer, and following the procedure described in the examples.

In general, as a method of suppressing warpage of a molded product in injection molding, an increase in the crystallization rate of the molding material can be mentioned, and by doing so, the molded product can be sufficiently crystallized in the mold. It suppresses warpage after taking it out of the mold.
However, on the other hand, in the modeling by the 3D printer, contrary to the above-mentioned method, the warp at the time of modeling can be suppressed by sufficiently slowing down the crystallization rate.

<Melting point peak>
In the modeling material of the present embodiment, it is preferable that the melting point peak measured by DSC shows a single peak. When the melting point peak shows a single peak, it can be said that the polyacetal and the other resin are sufficiently compatible with each other, and it is possible to make the modeling material uniform and improve the physical properties.
In addition, in this specification, "indicating a single peak" means that the existence of two or more peaks and shoulders is not confirmed.

Next, the components that can be contained in the modeling material in the present embodiment will be described.

<Polyacetal>
The modeling material in this embodiment has a polyacetal content (mass ratio) of 45% by mass or more. Further, from the viewpoint of exhibiting the advantageous properties of polyacetal, the modeling material preferably has a polyacetal content of 50% by mass or more, more preferably 55% by mass or more, and further preferably 60% by mass or more. Further, the modeling material preferably has a polyacetal content of 95% by mass or less, more preferably 90% by mass or less, still more preferably 80% by mass or less, from the viewpoint of improving the formability by a 3D printer. More preferably, it is 70% by mass or less.

Further, the modeling material in the present embodiment preferably has a polyacetal content (volume ratio) of 50% by volume or more. When the content (volume ratio) of polyacetal is 50% by volume or more, excellent properties such as mechanical strength and slidability peculiar to polyacetal are more likely to be exhibited. From the same viewpoint, the polyacetal content (volume ratio) of the modeling material is more preferably 53% by volume or more, further preferably 55% by volume or more. The content (volume ratio) of polyacetal is preferably 90% by volume or less, more preferably 80% by volume or less, and further preferably 60% by volume or less from the viewpoint of formability by a 3D printer.

Examples of the polyacetal in the present invention include polyacetal homopolymers (a-1) and polyacetal copolymers (a-2), but polyacetal copolymers are preferable from the viewpoint of formability and thermal stability. On the other hand, as the polyacetal, a polyacetal homopolymer is preferable from the viewpoint of the mechanical strength of the obtained modeled product.

[Polyacetal homopolymer (a-1)]
The polyacetal homopolymer (a-1) is a polymer having only an oximethylene unit in the main chain. Then, the polyacetal homopolymer (a-1) can be obtained, for example, by a known slurry polymerization method (for example, the methods described in Japanese Patent Publication No. 47-6420 and Japanese Patent Publication No. 47-10059).
Examples of commercially available polyacetal homopolymers include Tenac (trademark) manufactured by Asahi Kasei Corporation.

[Polyacetal copolymer (a-2)]
The polyacetal copolymer (a-2) is a copolymer polymer having an oxymethylene unit derived from the main monomer and a comonomer unit derived from the comonomer in the main chain. The comonomer unit is not particularly limited as long as it can be copolymerized with the oxymethylene unit, but is preferably an oxyalkylene unit having 2 or more carbon atoms. Both ends or one end of the polyacetal copolymer (a-2) may be sealed with an ester group and / or an ether group.
Examples of commercially available polyacetal copolymers include Tenac-C ™ manufactured by Asahi Kasei Corporation.

In the polyacetal copolymer (a-2), the quantification of the oxyalkylene unit having 2 or more carbon atoms can be determined by the following procedure using the ^{1 H-NMR method.}
That is, the polyacetal copolymer (a-2) was dissolved with hexafluoroisopropanol to a concentration of 1.5% by mass over 24 hours, and ¹ H-NMR analysis was performed using this solution to obtain an oxymethylene unit. From the ratio of the integrated value of the assigned peak to the oxyalkylene unit having 2 or more carbon atoms, the content ratio (b / a) of the oxyalkylene unit (bmol) having 2 or more carbon atoms to the oxymethylene unit (a = 100 mol). : Mol / 100 mol) can be obtained.

The polyacetal copolymer (a-2) preferably contains 0.3 mol or more, more preferably 0.4 mol or more, and more preferably 0.5 mol or more of the comonomer unit with respect to 100 mol of the oxymethylene unit. It is more preferably contained in an amount of 0.6 mol or more, and particularly preferably contained in an amount of 1.2 mol or more. Further, the polyacetal copolymer (a-2) preferably contains 3.0 mol or less of the comonomer unit, more preferably 2.0 mol or less, and further preferably 1.5 mol or less. By setting the content ratio of the comonomer unit to 100 mol of the oxymethylene unit within the above-mentioned preferable range, a modeling material having a good balance between formability and thermal stability by a 3D printer tends to be obtained.

1) Main Monomer Examples of the main monomer used in the production of the polyacetal copolymer (a-2) include cyclic oligomers such as formaldehyde, trioxane which is a trimer thereof, and tetraoxane which is a tetramer.
In the present embodiment, the "main monomer" means a monomer unit contained in an amount of 50% by mass or more based on the total amount of monomers.

2) Comonomer The comonomer used in the production of the polyacetal copolymer (a-2) is not particularly limited, and examples thereof include a cyclic ether compound having an oxyalkylene unit having 2 or more carbon atoms in the molecule.

The cyclic ether compound is not particularly limited, but for example, ethylene oxide, propylene oxide, 1,3-dioxolane, 1,3-propanediol formal, 1,4-butanediol formal, 1,5-pentanediol formal, 1,5-pentanediol formal, 1, Examples thereof include 6-hexanediol formal, diethylene glycol formal, 1,3,5-trioxepan, 1,3,6-triochiocane, and mono- or di-glycidyl compounds capable of forming a branched or crosslinked structure in the molecule.
The cyclic ether compound may be used alone or in combination of two or more.

The polyacetal in the present embodiment preferably has a weight loss rate of 5% or less when it is held at a temperature 10 ° C. lower than the melting point of the polyacetal for 1 hour. When the weight reduction rate is 5% or less, high thermal stability can be maintained, and the release of volatile organic substances (VOC) such as formaldehyde due to heating can be sufficiently suppressed. From the same viewpoint, the weight reduction rate is more preferably 3% or less, and further preferably 1% or less.
Here, the weight reduction rate is determined by using a thermal weight measuring device (manufactured by Perkin Elmer, trade name "Pyris1 TGA"), sample weight: 5 mg, air flow rate: 10 mL / min, and heating rate (from room temperature to 155 ° C.). Up to): Measure at 10 ° C./min, 155 ° C. (10 ° C. lower than the melting point of the prepared polyacetal copolymer) for 1 hour.

<Polylactic acid resin>
The modeling material in this embodiment preferably further contains a polylactic acid resin. Normally, polyacetal is difficult to be compatible with other resins, but it can be compatible with a certain proportion of polylactic acid. Therefore, when the modeling material further contains the polylactic acid resin, the modeling material can be made more uniform. Further, since the polylactic acid resin tends to be difficult to crystallize, the crystallization rate can be slowed down and the shrinkage degree value can be increased by further containing the polylactic acid resin in the modeling material.

As the polylactic acid resin, for example, various commercially available polylactic acid resins can be used. Further, as the polylactic acid resin, one obtained by polymerizing a cyclic dimer of lactic acid can also be used, and among lactides, L-lactide having a sufficiently low D-form content or L-lactide having a sufficiently low L-form content has been used. It is preferable to use D-lactide as a raw material, which is produced by a known melt polymerization method or in combination with a solid phase polymerization method.
One type of polylactic acid resin may be used alone, or two or more types may be used in combination.

The polylactic acid resin may contain polyglycolic acid, polycaprolactone, polybutylene succinate, polyethylene succinate, polybutylene adipate terephthalate, polybutylene succinate terephthalate and the like as subcomponents as long as the effects of the present invention are not impaired. It may contain one kind or two or more kinds of resins selected from the above.

The content of the polylactic acid resin in the modeling material is preferably 5 to 120 parts by mass with respect to 100 parts by mass of polyacetal. When the content of the polylactic acid resin is 5 parts by mass or more, warpage and delamination of the modeled product can be further suppressed, and when it is 50 parts by mass or less, the slidability which is an excellent property of polyacetal. Does not adversely affect such things. From the same viewpoint, the content of the polylactic acid resin in the modeling material is more preferably 10 parts by mass or more, further preferably 20 parts by mass or more, and 100 parts by mass with respect to 100 parts by mass of polyacetal. It is more preferably parts or less, and even more preferably 50 parts by mass or less.
In particular, low-priced 3D printers do not have a heater for the modeling stage or the modeling space is open in order to simplify the equipment, so heat retention is not sufficient and warpage and delamination are likely to occur. There is. Further, in the case of a large printer, since the temperature in the modeling area is not uniform, more advanced characteristics are required on the material side. Therefore, particularly in such cases, it is preferable that the modeling material further contains the polylactic acid resin in the above-mentioned ratio.

When the modeling material contains a polylactic acid resin, it is preferable that the modeling material further contains an inorganic filler described later. By using the polylactic acid resin and the inorganic filler in combination, the compatibility is further increased, and a uniform material having no composition distribution can be obtained.

<Inorganic filler>
The modeling material in this embodiment preferably further contains an inorganic filler. When the modeling material further contains an inorganic filler, the degree of shrinkage can be increased, and warpage and delamination of the modeled product can be further suppressed.

Examples of the inorganic filler include metal powders (aluminum, stainless steel, nickel, silver, etc.), hydroxides (aluminum hydroxide, magnesium hydroxide, calcium hydroxide, etc.), oxides (silicon oxide, iron oxide, alumina, etc.). Titanium oxide, zinc oxide, etc.), silicates (wallastnite, talc, mica, kaolin, clay, bentonite, glass beads, glass balloons, etc.), carbonates (calcium carbonate, magnesium carbonate, hydrotalcite, etc.), carbon-based Examples include substances (carbon black, graphite, carbon fiber, etc.), sulfates, boron nitride, silicon nitride, and the like. Among these, in the present embodiment, the inorganic filler preferably contains at least one selected from hydroxides, oxides, silicates, carbonates and carbon-based substances, such as wallastonite, mica, kaolin, and the like. It is more preferable to contain at least one selected from the group consisting of talc, glass beads, glass balloons, calcium carbonate and magnesium carbonate, and particularly from the viewpoint of not damaging the head of the 3D printer and having good compatibility with polyacetal. It is more preferable to contain calcium carbonate.
As the inorganic filler, one type may be used alone, or two or more types may be used in combination.

The inorganic filler may be surface-treated with a known surface-treating agent in order to improve the affinity with the resin. Examples of the surface treatment agent include silane coupling agents such as aminosilane and epoxysilane, titanate-based coupling agents, fatty acids (saturated fatty acids and unsaturated fatty acids), alicyclic carboxylic acids, resin acids, metal soaps, and resins. Can be mentioned. The amount of the surface treatment agent added is preferably 3% by mass or less, more preferably 2% by mass or less, based on the inorganic filler.

The shape of the inorganic filler may be powder, scale, plate, needle, spherical, cubic, fibrous, tetrapod, or the like, and is not particularly limited. However, the shape of the inorganic filler is preferably a cubic shape from the viewpoint of reducing anisotropy of the modeled product and improving mechanical strength, and the aspect ratio (L) which is the ratio of the average major axis (L) to the average minor axis (D) ( The one having L / D) of 5 or less is more preferable, and the one having L / D) of 3 or less is further preferable.

The average particle size of the inorganic filler is preferably 50 nm or more and 500 nm or less, more preferably 80 nm or more and 300 nm or less, and further preferably 80 nm or more and 200 nm or less. When the average particle size of the inorganic filler is 50 nm or more, the rigidity and toughness of the modeled product can be maintained at a high level even after being exposed to a high temperature for a long time. Further, since the average particle size of the inorganic filler is 500 nm or less, the toughness and gear strength of the modeled product can be maintained at a high level even after being exposed to a high temperature for a long time.
The average particle size, average major axis, and average minor axis of the inorganic filler are measured by sampling the inorganic filler particles to be measured with a scanning electron microscope (SEM), and the inorganic filler particles are magnified from a magnification of 1,000 times. The diameter was measured from at least 100 inorganic filler particles randomly selected in the obtained image taken at a magnification of 50,000, and the sum of the particles was calculated as an additive average.

The inorganic filler is preferably isotropic. Since the inorganic filler is isotropic, the anisotropy of the mechanical properties of the obtained modeled product can be suppressed. Examples of the isotropic inorganic filler include glass beads, calcium carbonate and the like.
In the present specification, "isotropic" means that the ratio of the major axis to the minor axis (major axis / minor axis) is 1.5 or less.

The content of the inorganic filler in the modeling material is preferably 5 to 120 parts by mass with respect to 100 parts by mass of polyacetal. If the content of the inorganic filler is 5 parts by mass or more, warpage and delamination of the modeled product can be further suppressed, and rigidity such as strength becomes good. If the content is 150 parts by mass or less, the material Does not impair the mechanical strength of. From the same viewpoint, the content of the inorganic filler in the modeling material is more preferably 20 parts by mass or more with respect to 100 parts by mass of polyacetal.

Hereinafter, calcium carbonate, which is an example of an inorganic filler, will be described.

An example of calcium carbonate that can be used in this embodiment is light calcium carbonate. Examples of the shape of the particles include a spherical shape, a cubic shape, a spun shape, a flaky shape, and an amorphous shape. The crystal form of light calcium carbonate may be any of the generally known calcite type, aragonite type and patelite type, and among these, interfacial adhesion with polyacetal and the composition machine. The calcite type is preferable from the viewpoint of improving the balance of physical properties. The light calcium carbonate is not particularly limited as long as it is artificially synthesized, and those called colloidal calcium carbonate, precipitated calcium carbonate or active calcium carbonate are preferable. Among these, those produced by reacting carbon dioxide with slurry-like calcium hydroxide are preferable.
As the light calcium carbonate, one type may be used alone, or two or more types may be used in combination.

The pH of calcium carbonate by the boiling extraction method based on the JIS K5101 test method is preferably 9.2 or more and 10.0 or less, and more preferably 9.4 or more and 9.7 or less. When this pH is 9.2 or more and 10.0 or less, the surface of the modeled product is less likely to be colored, which is preferable. Further, the maximum probability void radius by the mercury intrusion method using a mercury porosimeter of calcium carbonate is preferably 0.12 μm or more and 0.16 μm or less. When the maximum probability void radius is 0.12 μm or more, calcium carbonate is less likely to aggregate in the composition and a good dispersion can be obtained. It has the effect of maintaining a high level of rigidity and gear strength even after being exposed to calcium for a long time.

Calcium carbonate may be surface-treated or unsurface-treated. The term "surface treatment" as used herein means that at least one of a known surface treatment agent, adhesive or complexing agent, and anti-aggregation agent is added for the purpose of preventing particle aggregation in the calcium carbonate manufacturing process. As a result, it means that the surface of calcium carbonate is coated with the substance. Here, the surfactants, adhesives or complexing agents, and anti-aggregation agents are, for example, 232-237 of "Elucidation of dispersion / aggregation and applied technology, 1992" (supervised by Fumio Kitahara, published by Techno System Co., Ltd.). Examples thereof include anionic surfactants, cationic surfactants, amphoteric surfactants, and nonionic surfactants as described on the page. Further, silane coupling agents such as aminosilane and epoxysilane, titanate-based coupling agents, fatty acids (saturated fatty acids and unsaturated fatty acids), aliphatic carboxylic acids, resin acids and metal soaps are exemplified.

The surface treatment agent added when unsurface-treated calcium carbonate is used is not particularly limited, and specific examples thereof include fatty acids having 12 to 30 carbon atoms. A fatty acid having 12 to 30 carbon atoms is a fatty acid having a structure in which a carboxyl group is bonded to a linear or branched aliphatic hydrocarbon group, and has a total number of carbon atoms in the molecule of 12 to 30. Specifically, undecylic acid, lauric acid, tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, pentadecic acid, stearic acid, nanodecanoic acid, araquinic acid, bechenic acid, lignoseric acid, serotic acid, heptaconic acid, montanic acid, Examples thereof include melicic acid, laxel acid, undecylene acid, oleic acid, elaidic acid, setreic acid, erucic acid, brassic acid, linoleic acid, linolenic acid, arachidonic acid and stearolic acid.
These fatty acids may be used alone or in combination of two or more.

In addition, these fatty acids may be natural ones or synthetic ones. Further, the fatty acid may be substituted with a functional group such as a hydroxy group. Further, the fatty acid may be a synthetic fatty acid in which the terminal of uniphosphoric alcohol, which is a synthetic aliphatic alcohol, is carboxyl-denatured.

When calcium carbonate and a fatty acid having 12 to 30 carbon atoms are used, the mass ratio (fatty acid) / (calcium carbonate) of the above-mentioned fatty acid having 12 to 30 carbon atoms to calcium carbonate shall be 0.020 to 0.060. Is preferable, and 0.025 to 0.050 is more preferable. If it is 0.020 or more, the surface of calcium carbonate is sufficiently neutralized by fatty acids, and if it is 0.05 or less, the surface of the modeled product is less likely to be colored.

<Other ingredients>
The modeling material in the present embodiment includes, for example, addition of antioxidants, stabilizers (heat stabilizers, etc.), ultraviolet absorbers, crystal nucleating agents, conductive agents / antistatic agents, appearance improving agents (pigments, dyes, etc.). It may further contain an agent.

<Shape of modeling material>
The modeling material in the present embodiment is not particularly limited, but is preferably in the form of a monofilament from the viewpoint of being used as a modeling material for a 3D printer of the Fused Deposition Modeling method. In addition, in this specification, "monofilament-like" means a fibrous form consisting of one single yarn.
The monofilament-like modeling material (hereinafter, may be simply referred to as "monofilament") preferably has a diameter of 0.5 mm or more, more preferably 1.0 mm or more, and 1.4 mm or more. Is more preferable. If the diameter of the monofilament is less than 0.5 mm, it may become too thin and unsuitable for a 3D printer by a general-purpose fused deposition modeling method. The upper limit of the diameter of the monofilament suitable for a 3D printer by a general-purpose fused deposition modeling method is about 3 mm, but more preferably 2.0 mm or less, and further preferably 1.6 mm or less.
The diameter of the monofilament-shaped modeling material is a measurement of the major axis in a cross section cut perpendicular to the longitudinal direction.

Further, in the monofilament, the roundness represented by the ratio of the major axis to the minor axis (major axis / minor axis) is preferably 1.05 or less, and more preferably 1.03 or less. When the roundness is 1.05 or less, it is possible to more precisely model the modeled product in the 3D printer of the Fused Deposition Modeling method.
The closer the ratio of the major axis to the minor axis is, the higher the roundness is. By stretching the monofilament at the time of manufacturing, it is possible to obtain a monofilament having a high roundness.

Further, from the viewpoint of the stability of raw material supply, the diameter accuracy of the monofilament is preferably an error of ± 5% or less, and the difference between the maximum and minimum diameters measured at any 10 points is 0. It is preferably 0.05 mm or less.
By stretching during the production of the monofilament, the polymer chains of the resin are oriented and sufficiently crystallized, so that a monofilament having a low dimensional tolerance can be obtained.

<Manufacturing of modeling materials>
The molding material in the present embodiment is highly uniform by melt-kneading a resin such as polyacetal and any other component using a kneader, a roll mill, a single-screw extruder, a twin-screw extruder, a multi-screw extruder, or the like. It can be manufactured with sex.

Here, when performing melt-kneading, it is preferable to replace the atmosphere with an inert gas or degas by a one-stage or multi-stage vent in order to maintain the quality and working environment. The temperature at the time of melt-kneading is preferably 250 ° C. or higher than the melting point of the resin used, and may be 20 to 50 ° C. higher than the melting point of the resin used.

Next, a method of making the modeling material into a monofilament shape will be described with an example.
First, the molding material obtained after melt-kneading is melt-spun at a spinning speed of 5 to 30 m / min by a conventional method to obtain an undrawn monofilament. The spinning temperature at this time is appropriately set to 190 ° C. to 230 ° C., and if the spinning temperature is too low, it becomes difficult to completely melt the spinning temperature, and if it is too high, thermal decomposition of the polymer occurs, which is not preferable.

The spun unstretched monofilament is then cooled and solidified in a liquid bath at 0-100 ° C, preferably 20-80 ° C. If the cooling temperature is too low, temperature control becomes difficult and workability deteriorates, and if it is too high, cooling and solidification becomes incomplete, which is not preferable. Next, the unstretched monofilament that has been cooled and solidified is stretched without being wound once. At this time, a non-contact dry heat heater is installed between the rollers, and stretching is performed at a stretching ratio of 2 to 5 times while performing heat treatment at 170 to 250 ° C. When it is necessary to further stretch, the second and third steps are stretched while performing the same heat treatment between rollers having the same equipment. Then, after stretching, a non-contact dry heat heater is installed between the rollers, and relaxation heat treatment (stretching ratio is 0.9 to 0.99 times) is performed while performing heat treatment at 130 to 200 ° C.

After that, it can be wound up on a bobbin or the like and stored in a cartridge to finally obtain a monofilament-like modeling material. When the modeling material is made into a monofilament shape, it may be stretched at a magnification within a certain range.

<Use of modeling material>
The modeling material in this embodiment is suitably used for an additional manufacturing technique such as a 3D printer. The modeling material in the present embodiment can be specifically used for a 3D printer of the Fused Deposition Modeling method, and can also be used for a 3D printer of the powder melting method. By performing addition manufacturing using the modeling material in the present embodiment, it is possible to obtain a precise modeled product as designed. Further, the obtained modeled product can be widely applied to mechanical parts such as automobile parts, electric / electronic parts, industrial parts, medical parts and the like.

Hereinafter, as an example, a method of modeling with a 3D printer of the Fused Deposition Modeling method using the modeling material of the present embodiment in the form of a monofilament will be described.

In the supply of monofilament-shaped modeling material (monofilament), as described above, the fact that the monofilament is stored in the bobbin-shaped wound ridge is a stable feed and from environmental factors such as humidity. It is preferable from the viewpoint of protection and prevention of kinks and kinks.

When supplying the monofilament, it is common to engage the monofilament with a drive roll such as a nip roll or a gear roll and supply the monofilament to the extrusion head while taking it.

In the Fused Deposition Modeling method, the temperature of the heat extrusion head is preferably 180 to 240 ° C., and the substrate temperature is usually 80 ° C. or lower, so that a modeled product can be stably produced. The temperature of the molten resin (molten monofilament) discharged from the extrusion head is preferably 170 ° C. or higher, more preferably 190 ° C. or higher, and preferably 250 ° C. or lower, preferably 240 ° C. or lower. More preferably. When the temperature of the molten resin is equal to or higher than the above lower limit, it is preferable from the viewpoint of extrudability, and it is possible to prevent the molten resin from being left with thinly stretched fragments, which are generally called stringing, and deteriorating the appearance. It is also preferable from the viewpoint. On the other hand, when the temperature of the molten resin is equal to or lower than the above upper limit, it is easy to prevent problems such as thermal decomposition, burning, smoking, odor, and stickiness of the resin, and it is possible to discharge the resin at high speed, which improves the molding efficiency. It is preferable because it tends to be.

The molten resin discharged from the extrusion head is preferably discharged in the form of a slab having a diameter of 0.01 to 1 mm, more preferably 0.02 to 0.8 mm. It is preferable that the molten resin is discharged in such a shape because the reproducibility of the CAD model tends to be good.

(How to use modeling materials)
The method of using the modeling material of the present invention is characterized in that the modeling material in the above-described embodiment is used in a 3D printer of the Fused Deposition Modeling method. In the method of using the modeling material in the present embodiment, specific usage conditions and the like are not particularly limited, and the modeling material can be appropriately selected and used according to the purpose.

(Modeling method)
The modeling method of the present invention is a 3D printer of the fused deposition modeling method, and is characterized by modeling using the modeling material in the above-described embodiment. According to the modeling method in the present embodiment, since the modeling material in the above-described embodiment is used, it is possible to precisely model a complicated modeled product. In the modeling method of the present embodiment, specific modeling conditions and the like are not particularly limited, and modeling can be performed by appropriately selecting according to the purpose.

Hereinafter, the present invention will be described with reference to examples, but the present embodiment is not limited to the following examples. The methods of measurement and evaluation in Examples and Comparative Examples are as follows.

(1) Measurement of shrinkage degree PVT (pressure, specific volume, temperature) of the manufactured molding material is measured under the following conditions, and the specific volume at 50 ° C. with respect to the specific volume at 200 ° C. under a pressure of 0.1 MPa. The ratio, that is, the degree of contraction, was determined.
Measuring device: PVT TEST SYSTEM (manufactured by Toyo Seiki Seisakusho Co., Ltd.)
Measurement mode: Constant pressure temperature change Measurement temperature: 200 to 35 ° C (temperature lowering process)
Pressure level: 50-200MPa (0.1MPa is extrapolated)
Pre-drying: 80 ° C x 4h (hot air drying)
Sample shape: pellet

(2) Measurement of Crystallization Rate The crystallization rate of the manufactured pellet-shaped molding material was measured according to the following procedure using a differential scanning calorimeter (manufactured by Perkin Elmer: DSC-2C).
1: 3 mg of pellet-shaped modeling material is sealed in an aluminum pan for measurement and placed at a predetermined position in the heating furnace of the differential scanning calorimeter.
The temperature is raised to 220 ° C. at a heating rate of 2: 20 ° C./min.
3: Keep the temperature for 2 minutes after reaching 220 ° C.
The temperature is lowered until it reaches 149 ° C. at a temperature lowering rate of 4: 80 ° C./min, and the temperature is maintained for 10 minutes.
5: The time from the start of holding to the highest point of the exothermic peak is measured as the crystallization rate. The longer this time is, the slower the crystallization rate is.
The temperature is raised to 210 ° C. at a heating rate of 6: 20 ° C./min, and the temperature is maintained for 5 minutes.
Cool from 210 ° C to 100 ° C at a temperature lowering rate of 7:20 ° C / min.
The temperature is raised from 100 ° C. to 210 ° C. at a heating rate of 8:20 ° C./min, and the highest point of the endothermic peak (melting point peak) at that time is determined as the melting point.

(3) Observation of melting point peaks Observe the melting point peaks obtained in (2) above, and if the presence of two or more peaks and shoulders is not confirmed, it is judged as a single peak and two or more peaks or shoulders. Those whose existence was confirmed were judged to be non-single peaks.

(4) Measurement of diameter and roundness of monofilament 5 m of sample is taken out from the obtained monofilament-like modeling material (monofilament), 20 places are randomly selected, and their diameters are measured with a micrometer after the decimal point. Measured up to 4th place. Next, the fourth decimal place of those average values was rounded off to obtain the diameter of the monofilament.
In addition, 5 m of sample was taken out from the obtained monofilament, 20 points were randomly selected, and their major axis and minor axis were measured with a micrometer, and roundness = major axis / minor axis was set to the fourth decimal place. I asked for one place at a time. Next, the 5th decimal place of those average values was rounded off to obtain the roundness ratio of the monofilament.

(5) Evaluation of Warpage of Modeled Product Modeling was performed using the manufactured monofilament-shaped modeling material as a raw material. Specifically, "Da Vinci 1.0 Pro" manufactured by XYZ Printing Co., Ltd. is used as an extrusion lamination deposition system that employs the Fused Deposition Modeling method, and a cup-shaped modeled product (3) having an opening at the top as a three-dimensional object. Dimensional model) was modeled.
In modeling the modeled product, the printing speed was set to 60 mm / sec, the substrate temperature was set to 60 ° C, and the discharge temperature was set to 215 ° C. The molten resin was discharged from the extrusion head in the shape of a slab with a diameter of 0.4 mm.
The obtained modeled product was observed, and the warp of the modeled product was evaluated according to the following criteria.
Warp ◎: Almost no warp.
◯: Although it was slightly warped, a modeled product was obtained.
×: The warp is large and it cannot be modeled neatly.

(6) Evaluation of interlayer adhesion The interlayer adhesion of the molded product was evaluated according to the following criteria by observing the modeled product obtained as described in (5) above.
⊚: The layers were firmly adhered to each other, and a beautiful modeled product was obtained.
◯: A portion where the layers are slightly separated can be observed.
Δ: Delamination between layers is observed at a plurality of places.
X: The layers are largely separated, and a clean model cannot be obtained.

(Manufacturing of modeling materials)
Each component was melt-kneaded (cylinder-temperature: 160 ° C. to 210 ° C.) with a twin-screw kneader according to the formulation shown in Table 1 to obtain a perette-shaped molding material.
Next, the pellets obtained above were supplied to an extruder type melt spinning machine, melted at a spinning temperature of 200 ° C., and discharged from a round cross-section-shaped mouthpiece having one spinning hole having a diameter of 5 mm. The discharge amount at this time was adjusted so that the diameter of the yarn after drawing (diameter of the cross section) was 1.75 mm. Subsequently, the yarn was cooled and solidified in a liquid bath at 50 ° C. and taken up at a speed of 20 m / min to obtain an undrawn yarn. Next, after wiping off the moisture with a special sponge without winding the undrawn yarn once, it is drawn 4.09 times while being heat-treated at 230 ° C. with a non-contact dry heat heater installed between the rollers. bottom. After that, in the same non-contact dry heat heater installed between the rollers, while performing heat treatment at 150 ° C., relaxation heat treatment is performed at a draw ratio of 0.98 times to form a monofilament-like molding material (monofilament). Got

Table 1 shows the results of each measurement and evaluation performed in Examples and Comparative Examples.

* 1 Polyacetal: Asahi Kasei Corporation, "Tenac-C 4520"
* 2 Polylactic acid resin: "Ingeo 2003D" manufactured by Nature Works
* 3 Inorganic filler: calcium carbonate (manufactured by Shiraishi Kogyo Co., Ltd.), average particle size 150 nm, surface untreated, pH = 9.4, most probable void radius 0.13 μm, isotropic * 4 Polyacetal density: 1. Calculated from the mass ratio, assuming that 41 g / cm ³ , the density of polylactic acid resin: 1.24 g / cm ³ , and the density of the inorganic filler: 2.70 g / cm ^3.

As shown in Table 1, in the examples according to the present invention, it can be seen that the warp of the modeled product is suppressed and the interlayer adhesion is good, and a complicated modeled product can be precisely modeled.

According to the present invention, it is possible to provide a modeling material containing polyacetal, which can precisely model a complicated modeled product by a 3D printer. Further, according to the present invention, it is possible to provide a method of using the above-mentioned modeling material and a modeling method capable of precisely modeling a complicated modeled product.

Claims (11)

It is a modeling material for a 3D printer containing polyacetal, and the modeling material is
The content of the polyacetal is 45% by mass or more, and the content is 45% by mass or more.
Further containing an inorganic filler, the inorganic filler has an aspect ratio of 5 or less, and the content of the inorganic filler is 5 to 120 parts by mass with respect to 100 parts by mass of the polyacetal.
It further contains a polylactic acid resin, and the content of the polylactic acid resin is 5 to 120 parts by mass with respect to 100 parts by mass of the polyacetal.
Shrinkage obtained as the ratio of the specific volume at 50 ° C. for a specific volume at 200 ° C. is state, and are 0.875 or more,
The melting point peak measured by differential scanning calorimetry (DSC) indicates a single peak.
A modeling material for 3D printers. The modeling material according to claim 1, wherein the content of the polyacetal is 50% by volume or more. The modeling material according to claim 1 or 2 , wherein the crystallization rate is 35 seconds or more. The modeling material according to any one of claims 1 to 3 , wherein the inorganic filler is at least one selected from hydroxides, oxides, silicates, carbonates and carbon-based substances. The modeling material according to any one of claims 1 to 4 , wherein the inorganic filler is isotropic. The modeling material according to any one of claims 1 to 5 , wherein the inorganic filler has an average particle size of 50 nm or more and 500 nm or less. The modeling material according to any one of claims 1 to 6 , which is used for a powder melting method 3D printer. The modeling material according to any one of claims 1 to 6, which is used for a 3D printer of the Fused Deposition Modeling method. The modeling material according to any one of claims 1 to 6 , which is monofilament-like and has a roundness ratio of 1.05 or less represented by a ratio of a major axis to a minor axis. A method of modeling with a 3D printer of the Fused Deposition Modeling method, which comprises using the modeling material according to claim 9. The method for using a modeling material according to claim 9 , wherein the 3D printer is used in a fused deposition modeling method.