COPOLYCARBONATE AS A SUPPORTING MATERIAL IN 3-D PRINTING

Abstract

The invention relates to the use of copolycarbonates stable at high temperature as a supporting material in the FDM (fused deposition modeling) method, said copolycarbonates having a Vicat temperature determined in accordance with ISO 306:2013 of at least 150 C. Polyester, polyamide, PC/polyester blend, and/or polyaryl ether ketone is used as a printing material. Used as copolycarbonates are copolycarbonates containing one or more monomer units selected from the group consisting of the structural units of general formulas (1a), (1b), (1c), (1d), in which R.sup.1 represents hydrogen or C.sub.1 to C.sub.4 alkyl, R.sup.2 represents C.sub.1 to C.sub.4 alkyl, n represents 0, 1, 2, or 3, and R.sup.3 represents C.sub.1 to C.sub.4 alkyl, aralkyl, or aryl, and/or containing one or more monomer units of formula (1e), in which R.sup.19 represents hydrogen, Cl, Br, or a C.sub.1 to C.sub.4 alkyl residue, R.sup.17 and R.sup.18 are the same or different and represent, independently of each other, an aryl residue, a C.sub.1 to C.sub.10 alkyl residue, or a C.sub.1 to C.sub.10 alkylaryl residue, and wherein X is a single bond, CO, O, a C.sub.1 to C.sub.6 alkylene residue, a C.sub.2 to C.sub.5 alkylidene residue, a C.sub.5 to C.sub.12 cycloalkylidene residue, or a C.sub.6 to C.sub.12 arylene residue, which optionally can be condensed with further aromatic rings that contain heteroatoms, n is a number from 1 to 500, m is a number from 1 to 10, and p is 0 or 1.

Claims

1.-11. (canceled)

12. A process for producing a three-dimensional target object by means of fused deposition modeling using a support material, wherein a solvent is used to remove the support material, characterized in that the support material used is a composition based on a copolycarbonate having a Vicat temperature (VST/B120), determined according to ISO 306:2013, of at least 150 C., and wherein the copolycarbonate contains one or more monomer units of the formula (1a) ##STR00015## in which R.sup.1 is hydrogen or a C.sub.1- to C.sub.4-alkyl radical, R.sup.2 is a C.sub.1- to C.sub.4-alkyl radical, n is 0, 1, 2 or 3, (1b), (1c) and/or (1d) ##STR00016## in which R.sup.3 is a C.sub.1- to C.sub.4-alkyl radical, aralkyl radical or aryl radical, and/or of the formula (1e) ##STR00017## in which R.sup.19 is hydrogen, Cl, Br or a C.sub.1- to C.sub.4-alkyl radical, R.sup.17 and R.sup.18 are the same or different and are each independently an aryl radical, a C.sub.1- to C.sub.10-alkyl radical or a C.sub.1- to C.sub.10-alkylaryl radical, and where X is a single bond, CO, O, a C.sub.1- to C.sub.6-alkylene radical, a C.sub.2- to C.sub.5-alkylidene radical, a C.sub.5- to C.sub.12-cycloalkylidene radical or a C.sub.6- to C.sub.12-arylene radical, which may optionally be fused to further aromatic rings containing heteroatoms, n is a number from 1 to 500, m is a number from 1 to 10, p is 0 or 1, and wherein the print material used is a polyester, a polyamide, a PC/polyester blend and/or a polyaryl ether ketone, and wherein THF is used to remove the support material when the Vicat temperature (VST/B120), determined according to ISO 306:2013, is below 175 C. and/or a copolycarbonate having monomer units of the formulae (1b), (1c), (1d) and/or (1e) is used.

13. The process as claimed in claim 12, characterized in that the copolycarbonate contains one or more monomer units of the formula (1a) ##STR00018## in which R.sup.1 is hydrogen or a C.sub.1- to C.sub.4-alkyl radical, R.sup.2 is a C.sub.1- to C.sub.4-alkyl radical, n is 0, 1, 2 or 3.

14. The process as claimed in claim 12, characterized in that the copolycarbonate has been prepared from the monomers 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane and 2,2-bis(4-hydroxyphenyl)propane.

15. The process as claimed in claim 12, characterized in that the copolycarbonate has a Vicat temperature (VST/B120), determined according to ISO 306:2013, of at least 200 C.

16. The process as claimed in claim 12, characterized in that the copolycarbonate contains one or more monomer units of the formula (1b), (1c) and/or (1d) ##STR00019## in which R.sup.3 is a C.sub.1- to C.sub.4-alkyl radical, aralkyl radical or aryl radical, and THF is used as solvent for removal of the support material.

17. The process as claimed in claim 12, characterized in that the copolycarbonate contains one or more monomer units of the formula (1e) ##STR00020## in which R.sup.19 is hydrogen, Cl, Br or a C.sub.1- to C.sub.4-alkyl radical, R.sup.17 and R.sup.18 are the same or different and are each independently an aryl radical, a C.sub.1- to C.sub.10-alkyl radical or a C.sub.1- to C.sub.10-alkylaryl radical, and where X is a single bond, CO, O, a C.sub.1- to C.sub.6-alkylene radical, a C.sub.2- to C.sub.5-alkylidene radical, a C.sub.5- to C.sub.12-cycloalkylidene radical or a C.sub.6- to C.sub.12-arylene radical, which may optionally be fused to further aromatic rings containing heteroatoms, n is a number from 1 to 500, m is a number from 1 to 10, p is 0 or 1, and THF is used as solvent for removal of the support material.

18. The process as claimed in claim 12, characterized in that the support material is removed at a solvent temperature of 50 to 80 C.

19. The process as claimed in claim 12, characterized in that the support material is removed under the action of ultrasound.

20. The process as claimed in claim 12, characterized in that the print material used is a material having a processing temperature of at least 330 C.

21. A shaped article having a) a multitude of layers comprising copolycarbonate, comprising one or more monomer units of the formulae (1a), (1b), (1c), (1d) ##STR00021## in which R.sup.1 is hydrogen or a C.sub.1- to C.sub.4-alkyl radical, R.sup.2 is a C.sub.1- to C.sub.4-alkyl radical, n is 0, 1, 2 or 3, R.sup.3 is a C.sub.1- to C.sub.4-alkyl radical, aralkyl radical or aryl radical, and/or one or more of the monomer units (1e) ##STR00022## in which R.sup.19 is hydrogen, Cl, Br or a C.sub.1- to C.sub.4-alkyl radical, R.sup.17 and R.sup.18 are the same or different and are each independently an aryl radical, a C.sub.1- to C.sub.10-alkyl radical or a C.sub.1- to C.sub.10-alkylaryl radical, and where X is a single bond, CO, O, a C.sub.1- to C.sub.6-alkylene radical, a C.sub.2- to C.sub.5-alkylidene radical, a C.sub.5- to C.sub.12-cycloalkylidene radical or a C.sub.6- to C.sub.12-arylene radical, which may optionally be fused to further aromatic rings containing heteroatoms, n is a number from 1 to 500, m is a number from 1 to 10, p is 0 or 1, and b) a multitude of layers comprising a polyester, a polyamide, a PC/polyester blend and/or a polyaryl ether ketone.

22. The process as claimed in claim 12 or the shaped article as claimed in claim 21, wherein the polyester of the print material is a PBT and/or a PET.

Description

EXAMPLES

1. Description of Raw Materials

[0118] PC1: is a commercially available copolycarbonate based on bisphenol A and bisphenol TMC, having an MVR of 18 cm.sup.3/10 min (330 C./2.16 kg, ISO 1133-1:2011) and a softening temperature (VST/B 120; ISO 306:2013) of 183 C. (Apec 1895 from Covestro Deutschland AG). Lower bisphenol TMC content than PC2 and PC3. [0119] PC2: is a commercially available copolycarbonate based on bisphenol A and bisphenol TMC, having an MVR of 8 cm.sup.3/10 min (330 C./2.16 kg, ISO 1133-1:2011) and a softening temperature (VST/B 120; ISO 306:2013) of 202 C. (Apec 2097 from Covestro Deutschland AG). [0120] PC3: is a commercially available copolycarbonate based on bisphenol A and bisphenol TMC, having an MVR of 5 cm.sup.3/10 min (330 C./2.16 kg, ISO 1133-1:2011) and a softening temperature (VST/B 120; ISO 306:2013) of 218 C. (Apec DPI-9389 from Covestro Deutschland AG). [0121] PC4: is a copolycarbonate based on bisphenol A and a siloxane having the general structural formula (1e), where R.sup.19=H, X=isopropylidene, R.sup.17=R.sup.18=methyl radical, p=1, m=3-4, n=30, having an MVR of 25 cm.sup.3/10 min (320 C./2.16 kg, ISO 1133-1:2011), having a softening temperature (VST/B 120; ISO 306:2013) of <150 C. [0122] PC5: is a copolycarbonate based on bisphenol A and phthalimide (1c) with R.sup.3=phenyl, having a softening temperature (VST/B 120; ISO 306:2013) of >165 C. and less than 200 C. [0123] PC6: is a copolycarbonate based on bisphenol A and phthalimide (1b) with R.sup.3=methyl, having a softening temperature (VST/B 120; ISO 306:2013) of >165 C. and less than 200 C. [0124] PC7: is a commercially available polycarbonate based on bisphenol A having a partly branched structure, having an MVR of 2 cm.sup.3/10 min (300 C./1.2 kg, ISO 1133-1:2011) and a softening temperature (VST/B 50; ISO 306:2013) of 150 C. (Makrolon WB1239 from Covestro Deutschland AG). [0125] PC8: is a polycarbonate based on bisphenol A having partly branched structure, having an MVR of 12.6 cm.sup.3/10 min (300 C./1.2 kg, ISO 1133-1:2011) and a softening temperature (VST/B 50; ISO 306:2013) of 142 C. [0126] PC9: is a commercially available copolycarbonate based on bisphenol A and bisphenol TMC, having an MVR of 45 cm.sup.3/10 min (330 C./2.16 kg, ISO 1133-1:2011) and a softening temperature (VST/B 120; ISO 306:2013) of 158 C. (Apec 1695 from Covestro Deutschland AG). [0127] PC10: is a commercially available copolycarbonate based on bisphenol A and bisphenol TMC, having an MVR of 24 cm.sup.3/10 min (330 C./2.16 kg, ISO 1133-1:2011) and a softening temperature (VST/B 120; ISO 306:2013) of 173 C. (Apec 1795 from Covestro Deutschland AG). [0128] PLA: polylactic acid is a commercially available thermoplastic polymer for use in 3D printing from Orbi-Tech. [0129] PBT: is a commercially available polybutylene terephthalate from Lanxess (POCAN B 1300). [0130] PA-12: Nylon-12 is a commercially available thermoplastic polymer for use in 3D printing with a recommended processing temperature of 270 C. from Orbi-Tech. [0131] PC/PBT: is a commercially available elastomer-modified polycarbonate/polybutylene terephthalate blend based on a bisphenol A-based polycarbonate and polybutylene terephthalate, having an MVR of 16 cm.sup.3/10 min (260 C./5 kg, ISO 1133-1:2011) and a softening temperature (VST/B 120; ISO 306:2013) of 125 C. [0132] PET: is a commercially available polyethylene terephthalate from Invista (XPURE Polyester 4004/V004). [0133] PC: is a commercially available polycarbonate based on bisphenol, having an MVR of 19 cm.sup.3/10 min (300 C./1.2 kg, ISO 1133-1:2011) and a softening temperature (VST/B 120; ISO 306:2013) of 148 C. (Makrolon 2408 from Covestro Deutschland AG). [0134] PC/ABS: is a commercially available polycarbonate/acrylonitrile-butadiene-styrene blend having an MVR of 18 cm.sup.3/10 min (260 C./5 kg, ISO 1133-1:2011) and a softening temperature (VST/B 120; ISO 306:2013) of 130 C. (Bayblend T85XF from Covestro Deutschland AG). [0135] PC/ABS FR: is a commercially available flame-retardant polycarbonate/acrylonitrile-butadiene-styrene blend having an MVR of 18 cm.sup.3/10 min (260 C./5 kg, ISO 1133-1:2011) and a softening temperature (VST/B 120; ISO 306:2013) of 136 C. (Bayblend FR 331 ITV from Covestro Deutschland AG). [0136] ABS: is a terpolymer consisting of the monomers acrylonitrile, 1,3-butadiene and of the company Ineos Styrolution Europe GmbH (Terluran HI-10). [0137] Durabio: is a biodegradable polycarbonate based on isosorbitol from Mitsubishi Chemical. [0138] PEEK: is a commercially available polyetheretherketone from alt-intech. [0139] Xylene: isomer mixture of o-, m- and para-xylene, 98.5% by weight, available from Sigma-Aldrich. [0140] THF: tetrahydrofuran, 99.9% by weight, available from Sigma-Aldrich. [0141] MIBK: methyl isobutyl ketone, 298.5% by weight, available from Sigma-Aldrich. [0142] E3EP: ethyl 3-ethoxypropionate, 99% by weight, available from Sigma-Aldrich. [0143] Solv. mixture: a solvent mixture of 5% by weight of 1,3,5-trimethylbenzene (mesitylene), 2.5% by weight of cumene, 30% by weight of 2-methoxy-1-methylethyl acetate, 15% by weight of 1,2,4-trimethylbenzene, 30% by weight of ethyl 3-ethoxypropionate and 17.5% by weight of naphtha.

2. Experimental Procedure

[0144] A study of the solubility of various print material/support material combinations in various solvents was conducted at room temperature (table 1). For this purpose, a material specimen plaque (about 1.01.00.2 cm, 0.3 g) of the potential print material (PLA, PBT, PA-12, PC/PBT, PC/ABS, PET, PC, ABS, Durabio, PEEK) was bonded to a specimen plaque (about 1.01.00.2 cm, 0.3 g) of the support material (polycarbonate copolymer, polycarbonate). The materials were bonded by application of one drop of methylene chloride between the specimen plaques. After the bonded part had dried sufficiently, the specimens were placed into 10 mL of solvent for 24 h. Subsequently, the result was evaluated (both qualitatively and quantitatively by weighing before and after). Although adhesion of the individual layers to one another is induced thermally in conventional 3D printing, the bonding of the specimen plaques by solvent was intended to simulate a situation under severe conditions. The influence of the solvent causes print material and support material to enter into a significantly stronger bond to one another since it can be assumed that the two materials are partially dissolved and the two polymers interdigitate to a greater degree at the bonding site. Under these conditions, mutual detachment is possible only through adequate dissolution of the support material. In this case, detachment of the support material in the later printed part is significantly easier to achieve in the case of merely thermal bonding.

[0145] In a further test series, some copolycarbonate/print material combinations chosen by random sampling were subjected to dissolution tests at elevated temperature (table 2). Table 2 states the temperature used for the respective solvent, as well as the time for complete dissolution of the support material.

[0146] In addition, a test series was conducted (table 3) in which ultrasound was used additionally. The dissolution tests were started at room temperature. During the dissolution operation, the temperature increased owing to the energy input by ultrasound to a final temperature of the THF of about 35 C. and of the xylene to about 35 C. to 50 C.

[0147] All the copolycarbonates used can additionally be printed as support materials.

3. Results

[0148]

TABLE-US-00001 TABLE 1 Behavior of print material and support material under the influence of solvent a PC1 PC2 PC3 Solv. Solv. Solv. Xylene THF mixture MiBK E3EP Xylene THF mixture Xylene THF mixture PLA 1b 1c 2b 2b 2b 1b 1c 1b 1b 1c 1b PBT 1a 1a 2a 2a 2a 1a 1a 1a 1a 1a 1a PA-12 1a 1a 1a 1a 1a 1a 1a 1a 1a PC/PBT 1a 1a 1a 1a 1a 1a 2a 1a 1a PET 1a 1a 1a 2a 1a 1a 1a 1a 1a PC 1c 1c 2c 2c 2c 1c 2c 1c 1c 1c 1b ABS 1c 1c 2c 2c 2c 1c 1c 1c 1c 1c 1c PC/ABS 1c 1c 1c 1c 1c 1c 1c 1c 1c PC/ABS 1c 1c 1c 1c 1c 1c 1c 1c 1c FR Durabio 2c 1c 2c 2a 2a 1c 1c 1c 1c 1c 1c D5380AR Durabio 2c 1c 2c 2a 2a 1c 1c 1a 1c 1c 1a D7340AR PEEK 2a 2a 1a 1a 1a 1a 1a 1a 1a b PC4 PC5 PC6 Xylene THF Solv. mixture Xylene THF Xylene THF PLA 3b 1c 3b 3b 1c 3b 1c PBT 3a 1a 3a 3a 1a 3a 1a PA-12 3a 1a 3a 3a 1a 3a 1a PC/PBT 3a 1a 3a 3a 1a 3a 1a PET 3a 1a 3a 3a 1a 3a 1a PC/ABS 3c 1c 3c 3c 3c 3c PC/ABS 3c 1c 3c 3c 3c 3c FR c PC7 PC8 Xylene THF Solv. mixture Xylene THF Solv. mixture PC 3c 3c 3c 3c 2c 3c d PC10 PC9 Solv. Xylene Solv. mixture THF Xylene mixture THF PBT 3a 2a 1a 3a 3a 1a PA-12 3a 2a 1a 3a 3a 1a PC/PBT 3a 2a 1a 3a 3a 1a PET 3a 3a 1a 3a 3a 1a PC 3c 2c 1c 3c 3b 1c ABS 3c 2c 1c 3c 3c 1c PC/ABS 3c 2c 1c 3c 3c 1c PC/ABS 3c 2c 1c 3c 3c 1c FR Durabio 3c 2c 1c 3c 3c 1c D5380AR Durabio 3c 2c 1c 3c 3a 1c D7340AR PEEK 3a 2a 1a 3a 3a 1a Key: support materials in the first line of the table, print materials in the first column of the table. [1] support material fully dissolved; [2] support material incompletely dissolved after 24 h; [3] support material not dissolved; [a] print material undamaged and dimensionally stable; [b] print material hazy, but dimensionally stable; [c] print material destroyed (e.g. cracked, embrittled, broken up, partly dissolved); : not tested PC4 does not dissolve completely in most solvents, but breaks down into small pieces and can thus be separated from the print material (assessment I). Combinations with the assessment 2c (e.g. ABS as print material and PC1 as support material, solvent: MIBK) arc unsuitable both because the print material is destroyed in the chosen solvent and because it was possible to dissolve the support material only incompletely, if at all. By contrast, combinations with a 1a assessment are of excellent suitability since the support material can be dissolved completely in the chosen solvent and the print material remains undamaged. Examples of particularly suitable combinations of print material/support material are, according to table 1, for example, PEEK + PC2, PBT + PC2, PC/PBT + PC2 or PA-12 + PC3 (and others). The choice of solvent has a crucial influence on the suitability of combinations. The solvent mixture is suitable for dissolution of copolymers (PC2, PC3) having a high BPA-TMC content, but fails in the case of PC1 (assessment 2).

[0149] According to the results, a particularly suitable combination is: PEEK or PC/PBT as print material and PC2 as support material when THF or xylene is used for later dissolution of the support material.

[0150] PEEK and PC1 to PC3 in particular, i.e. the copolycarbonates for use in accordance with the invention that have monomer units of the formula (1a), have a very similar processing temperature and all have particularly high stability under prolonged thermal stress. Many other good combinations can be identified in the table. Good combinations were subsequently tested at elevated temperature or with ultrasound and the time for dissolution of the support material was examined (table 2 and table 3).

[0151] The polycarbonate homopolymer is suitable neither as print material nor as support material since it becomes cracked and brittle in the dissolution operation, but does not dissolve or become detached. The copolycarbonates PC8 and PC9 that have a partly branched structure are likewise unsuitable as support materials. They do not dissolve in the solvents tested and have only haziness and embrittlement.

[0152] Only the copolycarbonate PC7 shows good dissolution characteristics in THF and moderate dissolution characteristics in xylene. By comparison with PC2, however, it dissolves much more slowly.

TABLE-US-00002 TABLE 2 Behavior of print material and support material under the influence of solvent at elevated temperature. Time until complete dissolution of the support material. PC2 PC3 Xylene THF Xylene THF (75-80 C.) (50 C.) (75-80 C.) (50 C.) PBT 90 min 75 min 45 min 25 min PA-12 60 min 60 min 35 min 25 min PC/PBT 110 min 70 min 45 min 35 min PET 95 min 75 min 50 min 35 min PEEK 40 min 30 min 50 min 35 min Test parameters: THF = 50 C.; xylene = 75-80 C.; results as the average from double determination.

TABLE-US-00003 TABLE 3 Behavior of print material and support material under the influence of solvent at rising temperature through ultrasound. Time until complete dissolution of the support material. PC2 PC3 Solv. Solv. Xylene THF mixture Xylene THF mixture PBT 30 min 15 min 120 min 15 min 15 min 45 min PA-12 30 min 20 min 120 min 20 min 15 min 80 min PC/PBT 20 min 20 min 85 min 15 min 15 min 90 min PET 30 min 15 min 120 min 15 min 15 min 80 min PEEK 30 min 20 min 15 min 20 min Results as the average from double determination.

[0153] The tests conducted have shown that PEEK, PBT, PA-12, PC/PBT and PET are print materials that are suitable in principle, which can be used with bisphenol TMC-based copolycarbonates or the other copolycarbonates of high thermal stability used as support material in 3D printing, and that xylene, THF or the solvent mixture, especially THF and/or xylene, are suitable as solvents for dissolution of the bisphenol TMC-based copolymers. Using these solvents, the respective copolycarbonate can be dissolved without residue. In general, it took up to 24 h at room temperature for the support material to go completely into solution or for it to dissolve to such an extent that it became detached from the print material.

[0154] As well as bonding of the sample plaques of print material and support material with the aid of methylene chloride, these were also bonded by thermal means. For this purpose, one of the two materials in each case was heated briefly to about 400 C. with a hot air gun and the two sample plaques were subsequently pressed against one another until they had cooled down. The dissolution properties being studied were subsequently examined analogously to the above tests. The same dissolution behavior was found for the combinations specified.

[0155] The study of the solubility of the various print material/support material combinations at elevated temperature (table 2) showed that this not only increases the dissolution rate of the support material but also that, surprisingly, the print material is not attacked. At an elevated temperature of 50 C., both PC2 and PC3 dissolved within a maximum of 75 min. With a higher proportion of bisphenol TMC (PC3 versus PC2) in the copolycarbonate, it was possible to observe a rise in the dissolution rate.

[0156] As apparent from table 3, ultrasound treatment during the process of dissolution of the support material leads to a distinct increase in the dissolution rate. No effect of the ultrasound treatment on the print material was detected.