3d printing with enhanced interlayer adhesion

Abstract

Filaments for three-dimensional printing comprising a thermoplastic resin and an acrylic polymer additive in an amount ranging from 0.1 to 20 parts per hundred parts of thermoplastic resin (phr) are disclosed. Also disclosed are 3D printed articles made from the filaments and methods for making filaments for three-dimensional printing.

Description

Technical Field

[0001] The present invention relates generally to 3D printing, and more specifically to 3D filaments with enhanced interlayer adhesion. Background Technology

[0002] 3D printing has become a powerful tool for rapidly creating three-dimensional objects. From rapid prototyping parts in industry to enthusiasts creating 3D designs at home, 3D printing is a useful and flexible tool for creating complex objects. 3D printing is also used to produce parts for functional purposes. These parts may have complex shapes or require the high precision that 3D printing offers.

[0003] A common form of 3D printing is fused deposition modeling, in which polymer filaments are fed through heated nozzles to heat the filaments and extrude polymer, allowing it to be deposited in layers on top of previously formed layers to create 3D objects.

[0004] One of the problems with current 3D printing technology is low interlayer adhesion. Due to the additive nature of 3D printing, good adhesion of the material to the previously deposited material is important. Interlayer adhesion is driven by polymer melting.

[0005] For typical thermoplastics, polymer melting is driven by temperature and shear during melt processing. Higher shear typically provides faster melting.

[0006] Shear is a negligible factor in the 3D printing process. A lack of shear can lead to poor adhesion between deposited material layers. Poor adhesion can then cause structural failure in the 3D printed object. Poor interlayer adhesion can also lead to shrinkage and warping because the material cannot adhere properly within the 3D object.

[0007] Therefore, it is desirable to provide 3D printed filaments with improved interlayer adhesion. Summary of the Invention

[0008] The present invention provides filaments for three-dimensional printing comprising a thermoplastic resin and an acrylic polymer additive in an amount ranging from 0.1 parts to 20 parts per hundred parts of thermoplastic resin (phr).

[0009] They also disclosed 3D printed products made from filaments.

[0010] The present invention also relates to a method for preparing filaments for three-dimensional printing, the method comprising mixing a thermoplastic resin and an acrylic polymer additive to form a blend, wherein the acrylic polymer additive is present in an amount ranging from 0.1 phr to 20 phr, and extruding the blend in the form of a filament. Detailed Implementation

[0011] This invention provides filaments for 3D printing (such as, for example, fused deposition modeling (FDM)). As described below, these filaments exhibit excellent strength and interlayer adhesion. A method for preparing the filaments for 3D printing is also provided and described below.

[0012] The filament contains thermoplastic resin and acrylic polymer additives.

[0013] Examples of thermoplastic resins that can be used according to the present invention include, but are not limited to, polylactic acid (PLA), polyvinyl chloride (PVC), acrylonitrile butadiene styrene (ABS), polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PET), polyethylene terephthalate-propylene terephthalate (PETT), polybutylene terephthalate (PBT), polyamide (nylon), polyvinyl alcohol (PVA), polystyrene (PS), high-impact polystyrene (HIPS), and blends thereof. For example, the thermoplastic resin may comprise blends of thermoplastic resins, such as blends of polycarbonate with ABS, PET, or PBT. Preferably, the thermoplastic resin is selected from PLA or PVC. More preferably, the thermoplastic resin is PVC.

[0014] Acrylic polymer additives may comprise acrylic homopolymers or copolymers. For example, acrylic copolymers may be reaction products of one or more monomers selected from alkyl methacrylate monomers. Examples of alkyl methacrylate monomers include, but are not limited to, alkyl methacrylates comprising straight-chain or branched alkyl groups having 1 to 12 carbon atoms, such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, ethylhexyl acrylate, and isooctyl acrylate. Preferably, the alkyl methacrylate monomers comprise monomers selected from methyl methacrylate, ethyl methacrylate, and butyl methacrylate monomers.

[0015] Preferably, based on the total weight of the acrylic polymer additive, the acrylic polymer additive contains at least 25% by weight of units derived from methyl methacrylate monomers. More preferably, based on the total weight of the acrylic polymer additive, the acrylic polymer additive contains at least 30% by weight, even more preferably at least 35% by weight, and still more preferably at least 40% by weight of units derived from methyl methacrylate monomers. For example, based on the total weight of the acrylic polymer additive, the acrylic polymer additive may contain at least 50% by weight, at least 60% by weight, at least 70% by weight, or at least 80% by weight of units derived from methyl methacrylate monomers.

[0016] Exemplary acrylic polymer additives include, but are not limited to, copolymers of methyl methacrylate and at least one additional monomer selected from ethyl acrylate, butyl acrylate, and butyl methacrylate. For example, acrylic polymer additives may comprise terpolymers, such as terpolymers of methyl methacrylate, ethyl acrylate, and butyl methacrylate, or terpolymers of methyl methacrylate, butyl acrylate, and butyl methacrylate.

[0017] Acrylic polymer additives may also contain units derived from additional monomers, such as, for example, styrene monomers or functional monomers. As used herein, a “functional monomer” is a monomer containing an additional functional group, such as a functional group that will allow the acrylic copolymer to form covalent or hydrogen bonds with the thermoplastic resin or other components in the composition. Examples of functional monomers include monomers having hydroxyl groups.

[0018] Acrylic polymer additives may contain reaction products of monomers selected from methyl methacrylate monomers, butyl acrylate monomers, styrene monomers, and combinations thereof. For example, acrylic polymer additives may be reaction products of a combination of methyl methacrylate monomers and butyl acrylate monomers, or reaction products of a combination of methyl methacrylate monomers, butyl acrylate monomers, and styrene monomers.

[0019] Acrylic polymer additives can be linear or branched polymers. Alternatively, acrylic polymer additives may include crosslinking components, wherein the crosslinking components comprise some or all of the acrylic polymer additives. For example, acrylic polymer additives may include core-shell acrylic additives having a crosslinked core and a shell containing an acrylic homopolymer or copolymer.

[0020] The crosslinking core can be a reaction product of one or more monomers selected from the group consisting of alkyl (meth)acrylates and one or more crosslinking monomers, grafting monomers, or combinations thereof. For example, the amount of units derived from alkyl (meth)acrylate monomers may be in the range of 95% to 99.9% by weight of the core, and the amount of units derived from crosslinking monomers and / or grafting monomers may be in the range of 0.1% to 5% by weight.

[0021] The shell of a core-shell acrylic additive may include one or more layers, which may, for example, contain units derived from one or more monomers selected from the group consisting of alkyl (meth)acrylates, styrene monomers, and combinations thereof. The one or more layers of the shell may also contain units derived from one or more chain transfer agents.

[0022] For example, the shell of a core-shell acrylic additive may include one or more layers, each layer comprising 98.5% to 100% by weight of units derived from one or more monomers selected from the group consisting of alkyl (meth)acrylates, styrene monomers and combinations of two or more thereof, and 0% to 1.5% by weight of units derived from one or more chain transfer agents.

[0023] The alkyl group of the (meth)acrylate used in the crosslinked core or shell can be a straight-chain or branched alkyl group having 1 to 12 carbon atoms. Exemplary monomers include butyl acrylate, ethylhexyl acrylate, ethyl acrylate, methyl methacrylate, butyl methacrylate, and isooctyl acrylate.

[0024] Examples of crosslinking and / or grafting monomers that can be used in the crosslinked core or shell of core-shell acrylic additives may include, for example, butylene diacrylate, butylene dimethacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, divinylbenzene, diethylene glycol diacrylate, diethylene glycol dimethacrylate, diallyl maleate, allyl methacrylate, diallyl phthalate, triallyl phthalate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, blends thereof, and combinations of two or more thereof.

[0025] Core-shell acrylic additives can be produced by any conventional method such as multi-stage emulsion polymerization.

[0026] When the acrylic polymer additive is a linear or branched polymer, the acrylic polymer may have a weight-average molecular weight of at least 1,000,000 g / mol, such as, for example, at least 1,250,000 g / mol or at least 1,500,000 g / mol. Preferably, the acrylic copolymer has a weight-average molecular weight of less than 7,500,000 g / mol, such as, for example, less than 6,000,000 g / mol or less than 5,000,000 g / mol. When the acrylic polymer additive contains a crosslinking component, the weight-average molecular weight may be even lower, such as, for example, less than 1,000,000 g / mol or less than 750,000 g / mol.

[0027] The acrylic polymer additive is present in the filament in an amount ranging from 0.1 to 20 parts per 100 parts by weight of thermoplastic resin, i.e., 0.1 to 20 parts by weight of acrylic polymer additive per 100 parts by weight of thermoplastic resin. Preferably, the acrylic polymer additive is present in an amount of at least 0.25 phr, such as, for example, at least 0.5 phr or 1 phr. Preferably, the acrylic polymer additive is present in an amount of less than 15 phr or less than 10 phr.

[0028] Filaments can have diameters suitable for 3D printing. For example, common filament sizes for 3D printing include 1.75mm and 2.85mm. Other sizes can also be used.

[0029] Generally, acrylic polymer additives allow for a variety of advantages. When filaments are used in 3D printing processes, acrylic polymer additives can improve interlayer adhesion of printed materials. Acrylic polymer additives can also provide additional benefits such as improved shrinkage and warpage.

[0030] The composition may also contain additional components, such as stabilizers, antioxidants, lubricants, impact modifiers, plasticizers, UV stabilizers, flame retardants, colorants (e.g., pigments, dyes), or fillers. For example, the filament may also contain fillers selected from carbon fibers, natural fibers (e.g., wood fibers, bamboo fibers, cellulose), mineral fillers (e.g., calcium carbonate, mica), metal powders, and graphite. These fillers can impart additional properties to the filament and / or printed matter. For example, carbon fibers can impart additional strength, and metal powders and / or graphite can be used to make the material electrically conductive. These components are known in the art and can be used according to conventional practice.

[0031] A method for preparing filaments for 3D printing is also provided. This method includes mixing a thermoplastic resin and an acrylic polymer additive to form a blend, and extruding the blend in filament form.

[0032] The step of mixing thermoplastic resins and acrylic polymer additives may also include mixing additional components with the thermoplastic resins and acrylic polymer additives, such as colorants / dyes, fillers, or other components (e.g., stabilizers, antioxidants, lubricants, impact modifiers, plasticizers, UV stabilizers, flame retardants).

[0033] The components of the composition can be mixed in any order and by any suitable means. For example, thermoplastic polymer additives and acrylic polymer additives can be blended as dry components and then extruded to form filaments. Alternatively, acrylic polymer additives can be added as powder to molten thermoplastic resin.

[0034] The blended composition for preparing filaments can be formed under mixing, heating, or shearing, for example, using suitable mixing equipment. For example, the composition can be formed in a container or laboratory two-roll mill equipped with a stirrer and / or mixing blades. This container can be, for example, a mixer, such as a Banbury mixer, a Sigma (Z) blade mixer, or a cavitation transfer mixer. Alternatively or otherwise, the composition can be formed in or processed by an extruder, which can be any extruder, such as a single-screw extruder with a rotating and / or reciprocating (co-kneading) screw, and a multi-screw device comprising two or more screws that are tangentially or partially / fully meshing with each other, thereby rotating in co-rotational or counter-rotational directions. Alternatively, a conical extruder can be used to form the composition. The blended composition can then be extruded through a die of a suitable shape to form the filaments described herein. The method may also include cooling the filaments after extrusion.

[0035] The invention has been described by way of example, and it should be understood that the terminology used is intended to be descriptive rather than restrictive. Clearly, many modifications and variations of the invention are possible in accordance with the teachings above. The invention may be practiced in ways other than those specifically described.

[0036] Example

[0037] In an embodiment, PVC resin (available from Formosa Plastics) is used... 614) Compositions were prepared by blending with two different acrylic polymer additives in varying amounts. Examples 1 and 2 were prepared by blending 2 phr and 4 phr of a first acrylic polymer additive (APA1), which comprises a terpolymer of methyl methacrylate, ethyl acrylate, and butyl methacrylate having a weight-average molecular weight greater than 1,250,000 g / mol. The first acrylic polymer additive (APA1) comprises about 80 wt% methyl methacrylate. Examples 3 and 4 were prepared by blending 2 phr and 4 phr of a second acrylic polymer additive (APA2), which comprises a terpolymer of methyl methacrylate, butyl acrylate, and butyl methacrylate, wherein methyl methacrylate is about 85 wt% of the major component and has a weight-average molecular weight greater than 1,500,000 g / mol. The compositions of the examples are shown in Table 1 below, wherein all amounts are expressed in parts by weight relative to 100 parts of PVC resin. A similar composition without acrylic polymer additives was prepared as Comparative Example 1.

[0038] Table 1

[0039] PVC 100 100 100 100 100 TM 181 2 2 2 2 2 629A PE wax 0.2 0.2 0.2 0.2 0.2 Calcium stearate 0.8 0.8 0.8 0.8 0.8 XL 165 0.8 0.8 0.8 0.8 0.8 B3310 0.5 0.5 0.5 0.5 0.5 <![CDATA[TiO2]]> 5 5 5 5 5 <![CDATA[CaCO3]]> 4 4 4 4 4 K175 1 1 1 1 1 APA1 2 4 0 0 0 APA2 0 0 2 4 0 total 116.3 116.3 116.3 116.3 116.3

[0040] An exemplary polyvinyl chloride formulation was prepared by sequentially adding the materials shown in Formulation Table 1. A dry blend was prepared by adding PVC powder to a Gunther Papenmeier / Welex blender at room temperature, increasing the power to 15A, adding stabilizer TM 181 at 125℉, adding a lubricant pack at 150℉, adding an acrylic processing aid at 170℉, adding TiO2 at 190℉, and adding CaCO3 at 195℉. The powder dry blend was then cooled to room temperature.

[0041] To test the interlayer adhesion of the compositions, each composition was extruded to form a helical coil using a die with a diameter of 4.763 mm. To form the helical coil, the extrudate (i.e., filament) was rolled on a 1.5-inch diameter bar. Interlayer adhesion was measured using a Tinius Olsen universal testing machine. The two ends of the helical coil were locked in the two clamps of the universal testing machine, and then biaxially stretched until the helical coil layers separated or the sample broke. The sample with the acrylic polymer additive did not separate but broke, while the sample without the acrylic polymer additive failed due to layer separation. The loads required for layer separation and broken samples are shown in Table 2. As shown in Table 2, the embodiments according to the present invention exhibit significantly improved interlayer adhesion compared to Comparative Example 1.

[0042] Table 2

[0043] Example 1 33.6 Example 2 43.6 Example 3 27.0 Example 4 40.9 Comparative Example 1 9.3

[0044] Definition and usage of terms

[0045] Unless otherwise specified in the context of this specification, all quantities, ratios, and percentages are by weight, and all test methods are current methods as of the date of this disclosure. The articles “an,” “a,” and “described” each refer to one or more. It should be understood that the appended claims are not limited to the specific and particular compounds, compositions, or methods described in the detailed embodiments, which may vary among specific embodiments falling within the scope of the appended claims. Regarding any Markush group used herein to describe specific features or aspects of various embodiments, different, specific, and / or unexpected results can be obtained from each member of the respective Markush group, independent of all other Markush members. Each member of a Markush group can be relied upon individually and / or in combination and provides sufficient support for the specific embodiments within the scope of the appended claims.

[0046] Furthermore, any scopes and subscopes relied upon in describing the various embodiments of the invention fall independently and collectively within the scope of the appended claims, and should be understood as describing and contemplating all of the following scopes: all and / or some of the values ​​therein, even if these values ​​are not explicitly stated herein. Those skilled in the art will readily recognize that the enumerated scopes and subscopes adequately describe and enable the various embodiments of the invention, and that such scopes and subscopes can be further described as related halves, thirds, quarters, fifths, etc. By way of example only, the range “0.1 to 0.9” can be further described as the lower third (i.e., 0.1 to 0.3), the middle third (i.e., 0.4 to 0.6), and the upper third (i.e., 0.7 to 0.9), which are individually and collectively within the scope of the appended claims, and can be individually and / or collectively relied upon and provide sufficient support for specific embodiments within the scope of the appended claims. Furthermore, with regard to language that defines or modifies the scope, such as “at least,” “greater than,” “less than,” “not exceeding,” etc., it should be understood that such language includes subscopes and / or upper or lower limits. As another example, the scope of "at least 10" essentially includes sub-scopes of at least 10 to 35, at least 10 to 25, 25 to 35, etc., and each sub-scope can be relied upon individually and / or collectively to provide sufficient support for specific embodiments within the scope of the appended claims. Finally, independent numerical values ​​within the disclosed scope can be relied upon to provide sufficient support for specific embodiments within the scope of the appended claims. For example, the scope of "1 to 9" includes individual integers such as 3, and individual numbers including decimal points (or fractions) such as 4.1, which can be relied upon to provide sufficient support for specific embodiments within the scope of the appended claims.

[0047] As used herein, the term "composition" includes materials comprising the composition as well as reaction products and decomposition products formed from the composition materials.

[0048] The term "comprising" and its derivatives are not intended to exclude the presence of any additional components, steps, or procedures, whether or not such components, steps, or procedures are disclosed herein. For the avoidance of any doubt, unless stated to the contrary, all compositions claimed herein by using the term "comprising" may include any additional additives, adjuvants, or compounds, whether in polymeric or other forms. In contrast, the term "substantially composed of" excludes any other components, steps, or procedures from any subsequently listed scope, except those that are not essential for operability. The term "composed of" excludes any ingredients, steps, or procedures not specifically described or listed.

[0049] As used herein, the term "polymer" refers to a polymeric compound prepared by polymerizing monomers of the same or different types. Therefore, the general term "polymer" encompasses the term "homopolymer" (used to refer to a polymer prepared from only one type of monomer, where it should be understood that trace impurities may be incorporated into the polymer structure) and the term "copolymer" (used to refer to a polymer prepared from more than one type of polymer). Trace impurities may be incorporated into and / or within a polymer.

[0050] The terms "blend" and "polymer blend" mean a composition of two or more polymers. Such blends may or may not be miscible. Such blends may or may not be phase-separated. As determined by transmission electron spectroscopy, light scattering, X-ray scattering, and any other method known in the art, such blends may or may not contain one or more domain configurations. Blends are not laminates, but one or more layers of a laminate may contain blends.

Claims

1. A filament for three-dimensional printing, the filament comprising: Thermoplastic resins; and An acrylic polymer additive, wherein the amount of the acrylic polymer additive is in the range of 0.5 parts by weight to 10 parts by weight per hundred parts by weight of the thermoplastic resin, wherein the acrylic polymer additive comprises an acrylic copolymer, the acrylic copolymer being a reaction product of methyl methacrylate monomer and at least one additional monomer selected from ethyl methacrylate and butyl methacrylate monomer, wherein the acrylic polymer additive has a weight-average molecular weight of at least 1,000,000 g / mol; The thermoplastic resin is selected from the group consisting of: polylactic acid (PLA), polyvinyl chloride (PVC), acrylonitrile butadiene styrene (ABS), polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate-propylene terephthalate (PETT), polyamide (nylon), and blends thereof.

2. The filament according to claim 1, wherein the acrylic polymer additive comprises an acrylic copolymer, the acrylic copolymer being a reaction product of methyl methacrylate monomer, butyl acrylate monomer and at least one additional monomer selected from ethyl acrylate and butyl methacrylate monomer.

3. The filament according to claim 1, wherein the acrylic polymer additive comprises a core-shell acrylic additive.

4. The filament of claim 3, wherein the core comprises a reaction product of a (meth)acrylate alkyl ester monomer and a monomer selected from crosslinking monomers, grafting monomers and mixtures thereof, and wherein the shell comprises at least one layer comprising a reaction product of a (meth)acrylate alkyl ester monomer and one or more chain transfer agents.

5. The filament according to claim 3, wherein the core-shell acrylic additive comprises methacrylate butadiene styrene core-shell polymer.

6. The filament according to claim 5, wherein the shell of the methacrylate butadiene styrene core-shell polymer comprises methyl methacrylate.

7. The filament according to any one of the preceding claims, wherein the filament further comprises a filler selected from carbon fiber, wood fiber, metal powder and graphite.

8. The filament according to any one of claims 1-6, wherein the thermoplastic resin is selected from the group consisting of polyvinyl chloride and polylactic acid.

9. The filament according to any one of claims 1-6, wherein the acrylic polymer additive is present in an amount ranging from 1 to 10 parts by weight per hundred parts by weight of the thermoplastic resin.

10. The filament according to any one of claims 1-6, wherein the filament has an average diameter in the range of 1.0 mm to 5.0 mm.

11. A 3D printed article, said 3D printed article being prepared from a filament according to any one of the preceding claims.

12. A method for preparing filaments for three-dimensional printing, the method comprising: A thermoplastic resin and an acrylic polymer additive are mixed to form a blend, wherein the acrylic polymer additive is present in an amount ranging from 0.5 parts by weight to 10 parts by weight per hundred parts by weight of the thermoplastic resin; as well as The blend is extruded in the form of filaments; The acrylic polymer additives described herein comprise acrylic copolymers, which are reaction products of methyl methacrylate monomers and at least one additional monomer selected from ethyl (meth)acrylate and butyl (meth)acrylate monomers. The acrylic polymer additives thereon have a weight-average molecular weight of at least 1,000,000 g / mol. The thermoplastic resin is selected from the group consisting of: polylactic acid (PLA), polyvinyl chloride (PVC), acrylonitrile butadiene styrene (ABS), polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate-propylene terephthalate (PETT), polyamide (nylon), and blends thereof.