REACTIVE PRINTABLE COMPOSITION WITH ELASTOMERIC PROPERTIES

Abstract

The present invention relates to moisture curable compositions based on silane-terminated polymers in paste form that can be used as 3D printing materials and provide isotropic and elastomeric properties. The invention further relates to the use thereof as 3D printing materials and printing methods using said compositions.

Claims

1. A moisture-curable printable composition comprising a) at least one polymer having at least one terminal group of the general formula (I)
-A.sub.n-R—SiXYZ  (I), wherein A is a divalent bonding group containing at least one heteroatom, R is selected from divalent hydrocarbon residues having 1 to 12 carbon atoms, X, Y, Z are, independently of one another, selected from the group consisting of a hydroxyl group and C.sub.1 to C.sub.8 alkyl, C.sub.1 to C.sub.8 alkoxy, and C.sub.1 to C.sub.8 acyloxy groups, wherein X, Y, Z are substituents directly bound with the Si atom or the two of the substituents X, Y, Z form a ring together with the Si atom to which they are bound, and at least one of the substituents X, Y, Z is selected from the group consisting of a hydroxyl group, C.sub.1 to C.sub.8 alkoxy and C.sub.1 to C.sub.8 acyloxy groups, and each n is independently 0 or 1; and b) optionally at least one compound of the general formula (II) ##STR00004## wherein R′ is same or different and is, independently from one another, selected from the group consisting of a hydrogen atom and hydrocarbon residues having 1 to 12 carbon atoms, and Ar is selected from aryl groups; c) at least one filler; and d) at least one catalyst, wherein the composition is in form of a paste and has a yield stress of greater than 50, wherein the yield stress is calculated using the formula: ${\tau }^{\frac{1}{2}}=k_{\mathrm{oc}}^{\frac{1}{2}}+k_c^{\frac{1}{2}}{\gamma }^{\frac{1}{2}},$ wherein τ is the shear stress, k.sub.oc is the Casson yield stress, k.sub.c is the Casson plastic viscosity and γ is the shear rate.

2. The moisture-curable printable composition according to claim 1, wherein the at least one polymer a) (1) has at least two terminal groups of the general formula (I); (2) has a polyoxyalkylene backbone; (3) X, Y, and Z are, independently of one another, selected from a hydroxyl, a methyl, an ethyl, a methoxy, or an ethoxy group, wherein at least one of the substituents is a hydroxyl group, or a methoxy or an ethoxy group; (4) R in the general formula (I) is selected from a methylene, ethylene, or n-propylene group; and/or (5) A is an oxygen atom or an —NR″— group, where R″ is selected from the group consisting of a hydrogen atom, and alkyl or aryl residues having 1 to 12 carbon atoms, or is a substituted or unsubstituted amide, carbamate, urethane, urea, imino, siloxane, carboxylate, carbamoyl, amidino, carbonate, sulfonate or sulfinate group or a moiety comprising at least one of these groups.

3. The moisture-curable printable composition according to claim 1, wherein in the general formula (II) (1) Ar is a phenyl group; and/or (2) R′ is selected from a methyl or ethyl group.

4. The moisture-curable printable composition according to claim 1, wherein the composition comprises, relative to the total weight of the composition, (1) 10 to 50 wt.-% of the at least one polymer a); (2) 1 to 30 wt.-% of the at least one compound of the general formula (II); (3) 1 to 50 wt.-%, preferably 10 to 50 wt.-% of the at least one filler c); and/or (4) 0.01 to 1.0 wt.-% of the at least one catalyst (d).

5. The moisture-curable printable composition according to claim 1, wherein the filler comprises silica, relative to the total weight of the composition.

6. The moisture-curable printable composition according to claim 1, wherein the filler comprises calcium carbonate, optionally surface coated with fatty acids relative to the total weight of the composition.

7. The moisture-curable printable composition according to claim 1, wherein the composition further comprises at least one compound selected from the group consisting of plasticizers, reactive diluents, adhesion promoters, moisture scavengers, crosslinking agents, and light/UV stabilizers.

8. The moisture-curable printable composition according to claim 1, wherein the composition further comprises at least one crosslinker.

9. Method for manufacturing a three-dimensional part by extruded filament fabrication, the method comprising: (a) printing a moisture-curable printable composition according to any one of the preceding claims in a layer-by-layer manner to form the three-dimensional part; (b) curing the printed layers of the moisture-curable printable composition to obtain the three-dimensional part.

Description

EXAMPLES

[0149] Synthesis of Diphenyltetramethoxydisiloxane

[0150] Phenyltrimethoxysilane (195.2 g) was placed in a 3 neck round bottom flask (0.5 L) equipped with a magnetic stirring bar a thermometer and a dropping funnel. 1 N Hydrochloric acid (8.8 g with a molar ratio of water:methoxy 6:1) was added dropwise to the silane over a period of 7 h, whereby the temperature of the mixture was not allowed to exceed 40° C. The mixture was left stirring at 600 RPM for 10 h after which the reaction was stopped and the mixture stored at 25° C. for at least one day prior distillation. Conversion of the reaction after removal of the starting materials was 76%. Purification of the reaction mixture occurred via vacuum distillation. At a vacuum of 1 mbar two fractions were isolated. The first fraction came at 130° C. and contained unreacted phenyltrimethoxysilane. The second fraction was isolated at 230° C. and contained the desired product 1,2-diphenyltetramethoxydisiloxane (36% yield).

[0151] General Procedure for Manufacturing the Polymer

[0152] Polymer 1 (gamma-silane-terminated polymer): 282 g (15 mmol) of polypropylene glycol 18000 (hydroxyl value=6.0) was dried in a 500 ml three-neck flask at 80-90° C. under vacuum. Under a nitrogen atmosphere at 80° C., 0.1 g of dibutyltin laurate was added, and 7.2 g (32 mmol) 3-isocyanatopropyltrimethoxysilane (% NCO=18.4) was then added to it. After stirring for one hour at 80° C., the resulting polymer was cooled. After adding 3 g light stabilizer (Tinuvin 770 DF) and 6 g Geniosil XL 10 to the reactor while stirring and homogenizing for 10-30 minutes at 80° C., the resulting polymer was stored in a moisture-proof glass vessel under a nitrogen atmosphere before being processed further into a curable composition.

Example 1

[0153] The polymer, polyol, the additive, the filler, and the light stabilizer were mixed by combining them and stirring (for 10 minutes under nitrogen). In a next step, moisture scavenger was added and stirring was continued first without (3 minutes) and then under vacuum (12 minutes). Then adhesion promoter was added and stirring was continued first without (1 minute) and then under vacuum (10 minutes). Finally, the catalyst was added and stirring was continued first without (1 minute) and then under vacuum (15 minutes). All mixing was done under nitrogen atmosphere. The prepared formulations are shown in Table 1.

TABLE-US-00003 TABLE 1 Formulations (amounts in wt. % relative to total composition weight) 214 215 216 217 218 219 Polymer 1 31.5 46.5  46.5  31.5 31.5  51.5 Bis Ph-TMO (1,2- 15.0 — — — 15.0  15.0 Diphenyltetramethoxydisiloxane) Phenyltrimethoxysilane — — — 15.0 — — PPG 2000 (Acclaim polypropylene 14.8 14.8  14.8  14.8 14.8  14.8 glycol, OH-terminated) DBTL  0.2 0.2 0.2  0.2 0.2  0.2 Tinuvin 328 (light stabilizer)  0.5 0.5 0.5  0.5 0.5  0.5 Geniosil XL10 (Vinyltrimethoxysilane)  2.0 2.0 2.0  2.0 1.0  2.0 Geniosil XL32 — — — — 1.0  1.0 (Methacryloxymethyl)methyldimethoxysilane Geniosil GF91 (adhesion promoter)  1.0 1.0 1.0  1.0 1.0 — Chalk (Viscoexcel 30-SG) 35.0 35.0  30.0  35.0 35.0  15.0 Silica (HDK H18) — — 5.0 — — — Bis Ph-TMO: (Diphenyltetramethoxydisiloxane) DBTL: Dibutyltindilaurate Adhesion promoter: N-(2-aminoethyl)-3-aminopropyltrimethoxysilane Example 219 is a comparative example. Examples 214 to 218 are according to the invention.

Example 2

[0154] The formulations of Table 1 were analysed by determining their viscosity and shear stress at increasing shear rates from 0.3/s to 40/s at 25° C. (100 data points: starting from 0.3/s in increments of 0.3-0.4/s to 40/s) in an Anton-Paar rheometer MCR 302 according to BS EN ISO 3219:1995 From the obtained values, yield stress and plastic viscosity were calculated using the formula:

[00002]${\tau }^{\frac{1}{2}}=k_{\mathrm{oc}}^{\frac{1}{2}}+k_c^{\frac{1}{2}}{\gamma }^{\frac{1}{2}}$

TABLE-US-00004 TABLE 2 Rheological properties of formulations 214-219 214 215 216 217 218 219 Viscosity at 1/s (mPa .Math. s) 269.830 373.900 2.051.000 285.380 273.380 21.587 Viscosity at 5/s (mPa .Math. s) 82.578 132.950 503.900 74.085 81.038 13.391 Viscosity at 10/s (mPa .Math. s) 51.916 93.266 280.190 39.716 51.715 11.597 Viscosity at 40/s (mPa .Math. s) 24.841 53.029 94.234 15.967 23.521 9.293 Ratio 1/5 3.27 2.81 4.07 3.85 3.37 1.61 Ratio 1/10 5.20 4.01 7.32 7.19 5.29 1.86 Ratio 1/40 10.86 7.05 21.76 17.87 11.62 2.32 Yield stress (value) 202.15 223.80 1880.70 242.89 212.02 4.47 Plastic viscosity 7.64 24.13 11.01 2.16 6.51 7.39