Material Extrusion 3-D Printing on Compatible Thermoplastic Films

Abstract

To provide a compatible and miscible film having an excellent adhesion property to a printed component.SOLUTION: A polymer composite article comprises: a) a polymer article containing a crystalline or semi-crystalline polymer, which is made by a 3D printing process; and b) a polymer film adhered to the polymer article between the article and a base plate of a 3-D printer, in which the film is miscible, compatible or semi-compatible with the article, and the film has Tg having a temperature less than 50°C-lower than a printing temperature, preferably less than 80°C-lower than the printing temperature, more preferably less than 100°C-lower than the printing temperature.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to the use of compatible thermoplastic materials (films, sheets, or 3D printed materials) as base sheets, films, or layers for 3-D printing articles. The use of base films provides a means to print larger articles and reduce warping by printing directly onto the film. The printed article adheres better to the film than to traditional printer surfaces (glass, metal, glue, or reusable films) because the printed article and film are compatible, miscible, or semi-miscible in the melt, forming chain entanglements that fuse together. [Background technology]

[0002] It is necessary for the adhesion between the 3D printed part (material extrusion additive manufacturing) and the printer's build plate for the part to be printed to be strong. Because the position of the nozzle when extruding the material is determined by software before printing, if the printed part moves or warps during printing, the subsequent layers will not print correctly, resulting in molding defects.

[0003] Typically in 3-D printing, the article is printed directly onto glass or metal. Tape and glue sticks can be used to increase adhesion, but this only improves adhesion slightly. In situations where adhesion to glass or metal is poor, the surface can be further modified by placing an adhesion-promoting film, such as polyetherimide (PEI), on the build plate and printing over them. These films improve the adhesion of the print material to the build plate and allow the article to be released after printing. The film is meant to be reused. No permanent bond is formed between the print material and the adhesion-promoting film. Summary of the Invention [Problem to be solved by the invention]

[0004] One problem with 3D printing is that certain materials with good mechanical, chemical, or temperature stability tend to shrink or warp, and have poor adhesion to glass or metal base materials, or to PEI and other typical films. [Means for solving the problem]

[0005] Surprisingly, the compatible, miscible film of the present invention provides excellent adhesion to the printed part. The film is discarded or becomes a permanent part of the article. Without being bound to a particular theory, it is believed that the polymers of the film and the article are miscible, compatible, or semi-miscible in the melt, forming chain entanglements that lead to welding of the two polymers and preventing the article from pulling away from the base, leading to excellent adhesion and reduced warping. This is particularly important for crystalline and semi-crystalline polymers, which tend to warp more when 3D printed than amorphous polymer products.

[0006] The present invention relates to a 3D printed crystalline or semi-crystalline article welded to a polymer film, said polymer film having a glass transition temperature (Tg) of less than 50° C. below the printing temperature, preferably less than 80° C. below, more preferably less than 100° C. below.

[0007] Alternatively, the polymer film adhered to the article has a Tg or melting temperature (Tm) that is at least 10°C lower than the Tg or melting temperature (Tm) of the thermoplastic material of the article, preferably at least 20°C, preferably at least 30°C, or even more than 50°C lower.

[0008] The invention further relates to a process for forming a 3D printed article, comprising placing a polymer sheet between a glass build plate and an article to be printed, said polymer film being compatible, miscible or semi-miscible with said article in a molten state.

[0009] Within this specification, embodiments are described in a manner that enables a clear and concise specification to be written, but it is intended and understood that the embodiments can be combined or separated in various ways without departing from the invention, for example, it will be understood that all preferred features described herein are applicable to all aspects of the invention described herein.

[0010] Aspects of the invention include: (1) 3D printed items, including: a) a crystalline or semi-crystalline polymeric article; b) A polymer film adhered to the article between the article and a base plate of a 3-D printer, the film having a Tg of less than 50° C. below the printing temperature, preferably less than 80° C. below, and more preferably less than 100° C. below. (2) The article of aspect (1), wherein the crystalline or semi-crystalline polymer is selected from the group consisting of polyvinylidene fluoride homopolymers and copolymers, polyamides, polypropylenes, polyaryletherketones, polyetheretherketones, and polyetherketoneketones. (3) The article of side (1) or (2), wherein the crystalline or semi-crystalline article is a polyvinylidene fluoride homopolymer or copolymer and the film is selected from the group consisting of poly(meth)acrylate homopolymer or copolymer, polycaprolactone, and polylactic acid films. (4) The article of any of aspects (1) to (3), wherein the crystalline or semi-crystalline polymer article is a polyamide and the film is selected from the group consisting of amorphous polyamides or copolyamides, low melting point block polyetheramides, and polyamide-grafted polyolefins. (5) The article of any of aspects (1) to (4), wherein the crystalline or semi-crystalline polymer article is polypropylene and the film is selected from the group consisting of polyethylene and anhydride-grafted polyolefins. (6) The article of any of aspects (1) to (5), wherein the crystalline or semicrystalline polymer article is a semicrystalline polyetherketoneketone (PEKK) or polyetheretherketone (PEEK), and the film is selected from the group consisting of amorphous PEEK, amorphous PEKK, and polyetherimide. (7) 1. A 3D printed article, the article comprising: a) a crystalline or semi-crystalline polymeric article; b) a polymer film adhered to the article between the article and a glass base plate of a 3-D printer, the film having a Tg or Tm at least 10° C. lower than the Tg or Tm of the thermoplastic material of the article, preferably at least 20° C., preferably at least 30° C., or even more than 50° C.; Goods. (8) 1. A process for forming a 3D printed article, comprising: a) placing a polymeric film or sheet between a glass build plate and an article to be printed, said polymeric film being compatible, miscible or semi-miscible with said article in a molten state, said film or sheet having a Tg of less than 50° C. below the printing temperature, preferably less than 80° C. below, more preferably less than 100° C. below; b) applying the film and then increasing or decreasing the temperature of the build plate as needed; c) 3D printing an article onto said polymer film or sheet; A process including. (9) The process of side (8) where the polymer film and the 3D printed polymer article are welded together and have entangled polymer chains at the interface. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] film The films of the present invention are either compatible, miscible, or semi-miscible with the polymer filaments used to form the printed article. Miscible, semi-miscible, and compatible mean that the polymers can be blended in proportions such that a single homogenous mixture is produced without separation into separate bulk phases.

[0012] 3D printed objects adhere better to the film than to traditional printer surfaces or base plates (glass, metal, glue, and other films) because they form chain entanglements with the film's polymers, providing the best adhesion possible. The film is selected for its compatibility / miscibility with the object's polymer, Tg, and modulus, and is easily applied and discarded after each print. The film is not reused because it adheres so well to the object. The film's properties determine adhesion in each case and reduced warping.

[0013] The choice of film depends on the choice of polymer used in the extrusion additive manufacturing process of the 3D material. The film is selected for compatibility, miscibility, or semi-miscibility in the molten state. Preferably, the film is made of an amorphous or low crystalline material and has a Tg of less than 50°C, preferably 80°C, more preferably 100°C, lower than the printing temperature. For example, when the printing temperature is 260°C, the Tg of the film is less than 210°C, preferably less than 180°C, most preferably less than 130°C. Alternatively, if the film is selected from a semi-crystalline material, the film has a Tm of less than 50°C, preferably less than 80°C, lower than the printing temperature.

[0014] In another embodiment, in comparing the polymer of the 3D printed article to the polymer film, the Tg or Tm of the film is at least 10° C. lower than the Tg or Tm of the thermoplastic of said article, preferably at least 20° C., preferably at least 30° C., or even more than 50° C. "Tg" is used for amorphous polymers and "Tm" is used for crystalline or semi-crystalline polymers.

[0015] The term "film" includes sheets, rafts and films having thicknesses ranging from 30 μm to 10 cm, preferably 1 to 5 cm. Thicker films provide increased protection against warping.

[0016] Examples of films useful in the present invention include, but are not limited to, polycaprolactone, polylactic acid, (meth)acrylates, polyamides, polyimides, amorphous polyamides, functional polyolefins grafted with polyamide segments, and polyolefins doped with maleic anhydride grafted polyolefins.

[0017] In one embodiment, acrylic films are used in combination with polyvinylidene fluoride (PVDF) articles. The acrylic film adheres well to a heated glass plate near the Tg of the acrylic film. Acrylic copolymers with Tg higher or lower than that of polymethyl methacrylate can be used. Lower Tg films melt faster, providing faster welding and better adhesion, but lower Tg acrylates lose the benefit of reduced warpage. PVDF homopolymers and copolymers are known to be melt miscible with acrylic. When a PVDF layer is printed onto an acrylic film heated at 260°C, the high temperature interface effectively fuses the PVDF to the acrylic film, allowing entanglement of the PVDF and acrylic polymer chains, resulting in high adhesion between the film and the article. The use of an acrylic film does not prevent internal stresses, shrinkage and warpage, but it does limit separation from the build plate. The acrylic film essentially acts as a large raft underneath the forming 3D part. Raft and brim base materials are 3D printed directly onto the glass base, essentially providing an in situ thick film layer onto which the product can be printed. These are generally made of the same material as the product being printed. Raft and brim processes are envisaged as a means of implementing the invention where the printed base is a different material than the article, or where a raft or brim process of the same material as the article is used on the film of the invention. The advantage of a simple film over a raft or brim process is that the process requires very little additional time.

[0018] In one embodiment, the film of the present invention includes regions or phases that are not miscible, compatible or semi-compatible with the polymer of the 3D printed polymer article. Such mixed films provide the necessary adhesion to the 3D printed article while providing a means for removing the film from the article on which the immiscible, immiscible or semi-compatible regions are printed. Such films with both compatible and incompatible regions can be produced, for example, by coextrusion using multiple dies, alternating miscible, compatible or semi-compatible polymers with miscible, compatible or semi-incompatible polymers, resulting in strips of each polymer within one film. Another example means of producing a film with both compatible and incompatible regions can be a melt process of a blend of incompatible components followed by slow cooling to allow thermodynamic separation of the phases.

[0019] Articles (polymer filaments) Problems of poor adhesion, including warpage due to poor adhesion of glass to the build plate, are a particular problem for products made from crystalline and semi-crystalline polymer filaments, including, but not limited to, polyvinylidene fluoride, polyamide, polyetherketone, polyetheretherketone, and polypropylene. Other high warpage materials include ABS and other styrene block copolymers. The significant warpage and poor base plate adhesion of these materials have limited the size of articles made from these materials by 3D printing.

[0020] Specific combinations of semi-crystalline or crystalline articles with the films of the present invention include, but are not limited to, the following: · Polyvinylidene fluoride articles on poly(meth)acrylate homopolymer or copolymer films. · Polyvinylidene fluoride articles on polycaprolactone films. ·Polyvinylidene fluoride articles made of polylactic acid film. Polyamide articles such as PA11 or PA12 on amorphous polyamides or copolyamides (e.g. RILSAN® clear resins from Arkema Inc.). Polyamide articles on low melt block polyetheramides (such as PEBAX® resins from Arkema Inc.). Polyamide articles on polyamide grafted polyolefins (e.g. APOLHYA® from Arkema Inc.). · Polypropylene over polyethylene. · Polypropylene on anhydride grafted polyolefin. Semi-crystalline polyetherketoneketone (PEKK) or polyetheretherketone (PEEK) articles on amorphous polyetherketoneketone or polyetheretherketone, e.g. PEKK7000 series resins from Arkema Inc. on amorphous PEKK600 series resins from Arkema Inc. The Tg of PEKK6000 resin is about 160°C, the print temperature of PEKK7000 is about 350°C. ·PEKK or PEEK articles with PEI film (polyetherimide with a Tg of approximately 210°C).

[0021] The crystalline or semi-crystalline polymer composition may further optionally comprise less than 50 weight percent, preferably less than 40 weight percent, more preferably less than 30 weight percent, or even less than 20 weight percent or less than 10 weight percent of other miscible, compatible or semi-compatible polymers and / or less than 50 weight percent, preferably less than 40 weight percent, more preferably less than 30 weight percent, or even less than 20 weight percent or less than 10 weight percent of a filler material, the weight percent being based on the total weight of the crystalline or semi-crystalline polymer.

[0022] In one embodiment, the alloy is at least 50 weight percent, more preferably at least 60 weight percent, more preferably at least 70 weight percent PVDF homopolymer or copolymer with a polymethyl methacrylate (PMMA) homopolymer or copolymer. The PMMA copolymer of the alloy contains at least 50 weight percent, more preferably at least 75 weight percent methyl methacrylate monomer units. The melt miscible blend of PVDF and PMMA offers many surprising advantages, including reduced and controlled warpage, improved light transmission when desired, reduced shrinkage, improved base adhesion, improved adhesion between layers, and improved mechanical properties in the z-direction. Additionally, the overall print quality is surprisingly improved. Low and ultra-low viscosity compatible or miscible non-fluoropolymers can also be used to improve printability.

[0023] Useful compatible non-fluoropolymers can be block copolymers that contain at least one miscible block. The immiscible block can provide other properties, such as enhanced impact resistance, ductility, optical properties, adhesive properties, etc. Both blocks can include functional groups. In one embodiment, poly(meth)acrylate homo- and copolymer blocks can be used as the compatible block in the block copolymer.

[0024] Blends of fluoropolymers with other fluoropolymers or non-fluoropolymers can be accomplished by any practical means, including physically blending the different polymers as dry components, or in latex form, or in the melt. In one embodiment, filaments of two or more polymers are coextruded in a core-sheath, islands-in-the-sea, or other physical configuration.

[0025] In one embodiment, the filler is selected from the group consisting of carbon fibers, crushed carbon fibers, carbon powder, carbon nanotubes, glass beads, glass fibers, nanosilica, aramid fibers, polyaryletherketone particles or fibers, BaSO4, talc, CaCO3, graphene, nanofibers, impact modifiers, hollow spheres, and mixtures thereof.

[0026] process The inventive film, containing the desired composition, Tg, modulus, thickness and other factors, is cut to the desired size, placed on a heated build plate (with or without adhesive), pressed evenly against the build plate with light pressure, and the selected filament is printed onto the film. Once cooled, the film can be removed from the article and is typically discarded.

[0027] A typical process for using acrylic film is as follows. · Heat the glass build plate to between 85C-95C (Tg of the film). Wear protective gloves. Place the acrylic film onto the heated glass build plate. Use a cloth or paper towel to press the film evenly across and across the glass. Scrub to remove air bubbles. The temperature of the build plate can be adjusted to a value close to the Tg of the acrylic film, but in any case it should be close or slightly higher. After applying the film, you can increase or decrease the temperature of the heated glass build plate as needed. Range: 60℃~120℃; · 3D print objects onto acrylic film. Once the print is complete, remove it from the build plate. Cut away any excess film from the 3D printed part. Any acrylic film that is in contact with the part cannot be peeled off.

[0028] Alternatively, the acrylic film (typically 50-350 micrometers) can be increased to a sheet thickness of over 350 μm to counter internal stresses during cooling that may cause the printed PVDF article to detach from the build plate. In this case, a double-sided pressure-sensitive adhesive tape can be used between the acrylic sheet and the glass build plate. In this respect, heating the build plate does not change anything, since the build plate does not affect the temperature of the sheet (because the sheet is thick); therefore, the print is essentially made onto a room temperature print bed.

[0029] Alternatively, as mentioned above, a printer with two or more nozzles can be used to print a compatible film, with a compatible, low warp material printed first as a first or raft layer, and then the desired material printed on top. EXAMPLES

[0030] Example 1 Using the above process, 3D printed articles were fabricated on the following materials, as shown in Table 1. The table includes the approximate maximum sizes of 3D printed PVDF homopolymer parts possible with various build plate / base bonding conditions.

[0031] [Table 1]

[0032] Example 2 Using the above process, the following films of material were used: The 3D printed article is polyamide 11. Base Material: Brim: All parts came off except for very small pieces. · Raft: Parts came off. Glue coating: Can be held when using a large amount of glue, only small parts (<5cm) can be held. Acrylic film: No chemical interaction, worse than no film. PEI film: OK for bonding small parts (<5cm). ·Arkema Amorphous Polyamide Film (70μm): Stronger adhesion than PEI and adhesives.

Claims

1. A polymer composite article comprising: a) a polymeric article comprising a crystalline or semi-crystalline polymer produced by a 3D printing process; b) a polymer film adhered to the polymer article between the polymer article and a base plate of a 3-D printer, the polymer film having a thickness of 30 μm to 10 cm, being miscible, compatible, or semi-compatible with the polymer article, the polymer film having a Tg of less than 50° C. below the printing temperature, and having a Tg or Tm at least 30° C. below the Tm of the crystalline or semi-crystalline polymer.

2. 2. The polymer composite article of claim 1, wherein the crystalline or semi-crystalline polymer is selected from the group consisting of polyvinylidene fluoride homopolymers and copolymers, polyamides, polypropylene, polyetheretherketones, polyetherketoneketones.

3. 10. The polymeric article of claim 1, wherein the polymeric article comprising the crystalline or semi-crystalline polymer further comprises up to 50 percent by weight of a miscible, compatible or semi-compatible polymer.

4. 10. The polymeric article of claim 1, wherein the polymeric article comprising the crystalline or semi-crystalline polymer further comprises up to 50 percent by weight of one or more fillers.

5. 3. The polymeric article of claim 2, wherein the crystalline or semi-crystalline polymer is a polyamide and the polymeric film is selected from the group consisting of amorphous polyamides or copolyamides, low melting point block polyetheramides, and polyamide-grafted polyolefins.

6. 3. The polymeric article of claim 2, wherein the crystalline or semi-crystalline polymer is polypropylene and the polymeric film is selected from the group consisting of polyethylene and anhydride-grafted polyolefins.

7. 3. The polymeric article of claim 2, wherein the crystalline or semi-crystalline polymer is semi-crystalline polyetherketoneketone (PEKK) or polyetheretherketone (PEEK) and the polymeric film is selected from the group consisting of amorphous PEEK, amorphous PEKK, and polyetherimide.

8. 10. The polymeric article of claim 1, wherein the polymeric film comprises up to 40 weight percent of a polymeric phase that is not miscible, compatible or semi-compatible with the polymeric article.

9. 1. An article produced by 3D printing, the article comprising: a) a crystalline or semi-crystalline article; b) a polymer film adhered to the article between the article and a glass base plate of a 3D printer, the polymer film having a thickness of 30 μm to 10 cm and a Tg or Tm at least 30° C. lower than the Tg or Tm of the thermoplastic material of the article; Goods.

10. 1. A process for forming a 3D printed article, comprising: a) placing a polymeric film or sheet between a glass build plate and an article to be printed, said polymeric film or sheet having a thickness of 30 μm to 10 cm, said polymeric film or sheet being compatible, miscible or semi-miscible with said article in a molten state, said polymeric film or sheet having a Tg of less than 50° C. below the printing temperature and having a Tg or Tm of at least 30° C. below the Tg or Tm of the thermoplastic of said article; b) increasing or decreasing the temperature of the build plate after applying the polymer film or sheet; c) 3D printing an article onto said polymer film or sheet; A process including.

11. The process of claim 10 , wherein the polymeric film and the article are welded together and have entangled polymer chains at the interface.

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