NEW USE OF ISOSORBIDE

Abstract

The present invention relates to the use of a composition comprising isosorbide diglycidyl ether and a curing agent as a sacrificial support, to a sacrificial support comprising isosorbide repeating units, to methods for producing the sacrificial support of the invention and to uses of the sacrificial support of the invention for producing three-dimensional objects.

Claims

1. A method of producing a sacrificial support, the method comprising: curing a composition comprising isosorbide diglycidyl ether and a curing agent to form a sacrificial support.

2. The method of claim 1, wherein the curing agent has at least one amine-functional group having at least one active hydrogen linked to an amine nitrogen.

3. The method of claim 1, wherein the curing agent has two amine functional groups each having at least one active hydrogen linked to an amine nitrogen.

4. The method of anyone of claim 1, wherein the composition further comprises at least one organic filler.

5. The method of claim 4, wherein the at least one organic filler includes one or more of a phenolic resin, an acrylic resin, poly(vinyl alcohol), poly(vinyl acetate), ethylene-vinyl acetate, and rubber.

6. The method of claim 1, wherein the composition further comprises at least one foaming agent.

7. The method of claim 6, wherein the at least one foaming agent includes one or more of a siloxane, polymethylhydrosiloxane, silicone hybride, and a silicone derivative.

8. A sacrificial support for producing a three-dimensional object, the sacrificial support comprising a polymer including isosorbide ether repeating units.

9. The sacrificial support of claim 8, wherein the polymer further comprises amine groups.

10. The sacrificial support of claim 8, wherein the sacrificial support has a Tg between 50 and 180 C., measured via differential scanning calorimetry according to ASTM D 3418.

11. The sacrificial support of claim 8, wherein the sacrificial support has elongation at break in the range of 3.5 and 10.5% measured at 25 C. according to ASTM D 638.

12. A process for producing a sacrificial support for producing a three-dimensional object, wherein the sacrificial support comprises a polymer including isosorbide ether repeating units, the process comprising: providing a composition comprising isosorbide diglycidyl ether and a curing agent; casting the composition in a mould; at least partially curing the composition; and separating the cured composition from the mould to obtain the sacrificial support.

13. The process of claim 12, wherein the curing is performed for a time in the range of 2 and 30 hours.

14. A process for preparing a three-dimensional object, the process comprising: producing a sacrificial support according to the process of claim 12; depositing a material at least partially covering the sacrificial support, wherein the material comprises a polymer; and removing the sacrificial support from the deposited material to obtain the three dimensional object.

15. The process of claim 14, wherein removing the sacrificial support from the deposited material comprises contacting the sacrificial support with an aqueous acidic solution.

16. The process of claim 14, wherein the deposited material comprises a curable polymer, and the process further comprises curing the curable polymer before removing the sacrificial support from the deposited material.

17. A method of manufacturing a three-dimensional composite object, the method comprising: applying a composite material to the sacrificial support produced by the process of claim 12.

Description

EXAMPLES

Example 1Comparative Example

[0101] Curable Reference Epoxy Composition

[0102] An epoxy formulation containing 34.2% by weight of liquid bisphenol A based epoxy resin with a number average molecolar weight 700 g/mol, 40.9% liquid bisphenol F based epoxy resin with a number average molecolar weight 700 g/mol, 24.2 wg. % of 1,6-bis(2,3-epoxypropoxy)hexane and 0.7 wg. % of Airex 900 as antifoaming agent was formulated, homogeneized and degassed.

[0103] A hardener formulation comprising 50.7 wg. % of poly(propylene glycol) bis(2-aminopropyl ether) with a number average molecular weight of 230 g/mol, 34.1 by weight of 2-(1-piperazinyl)ethylamine, 8.2% by weight of 3-aminomethyl-3,5,5-trimethylcyclohexylamine and 7% by weight of 4,4-isopropylidenediphenol was prepared, homogeneized and degassed.

[0104] 100 parts by weight of the epoxy formulation were mixed with 33 parts by weight of the hardener formulation.

[0105] The system was cured 15 hours at 60 C.

Example 2

[0106] 100 parts by weight of a commercially available liquid isosorbide diglycidyl ether having an epoxide equivalent weight of 165 was mixed with 34 parts by weight of the formulated hardener having the same composition as the hardener formulation of Example 1.

[0107] The system was cured 15 hours at 60 C.

[0108] Table 1 summarizes the viscosity and reactivity behavior of the composition of comparative Example 1 based on bisphenol A epoxy resin and the composition using the same curing agents of Example 1 but using isosorbide diglycidyl ether epoxy instead of bisphenol A. The initial mixture viscosity refers to the viscosity of the two mixed components measured by a Brookfield viscosimeter at 40 C., with a 21 spindle moving at 10 RPM. Gelation time was measured following UNI 8701. Pot life and exothermic peak refer to the following test: 100 mL of the system are cured at 232 C. while measuring the thermal excursion with a temperature probe immersed in the system and connected to a recording system. Pot life is the time that the system needs to reach 40 C., while exothermic peak is the maximum temperature achieved during curing.

[0109] Table 2 shows the mechanical and thermal properties of the cured compositions of comparative Example 1 and of Example 2 according to the invention. Glass transition temperature was measured via differential scanning calorimetry following ASTM D 3418; tensile properties were performed accordingly to ASTM D 638; flexural properties were measured accordingly to ASTM D 790.

TABLE-US-00001 TABLE 1 Comparative Property Conditions Example 1 Example 2 Initial mixture 40 C. 100 100 viscosity (mPa .Math. s) Pot life, doubled 40 C. 205 85 initial viscosity Gelation time (min) 25 C., 100 mL 328 124 Pot life (min) 25 C., 100 mL 25 9 Exothermic peak ( C.) 176 159

TABLE-US-00002 TABLE 2 Comparative Property Conditions Example 1 Example 2 Glass transition ( C.) Ramp 70/64 58/56 1.sup.st/2.sup.nd scan 10 C./min Flexural strength 25 C. 111 1.4 120 1.4 (MPa) Flexural Maximum strain 5.2 0.1 4.2 0.1 (%) Flexural Strain at break 9.3 0.9 8.8 0.7 (%) Flexural elastic modulus 3150 80.sup. 3980 75.sup. (MPa) Tensile strength (MPa) 77 1.8 82 1.8 Tensile Maximum strain 8.0 1.4 6.8 1.1 (%) Tensile Strain at break 9.3 1.3 7.1 1.2 (%)

[0110] As stated above, the composition of Example 2 was obtained using the same ingredients with respect to the composition of Example 1 except that the bisphenol A of the epoxy element was substituted by isosorbide.

[0111] The results on the mechanical and thermal analysis of the two compositions summarized in Tables 1 and 2 revealed that the properties necessary for obtaining a support material, which can be used for the production of three-dimensional objects are maintained.

Example 3

[0112] 100 parts by weight of liquid isosorbide diglycidyl ether having an epoxide equivalent weight of 165 was mixed with 18 parts by weight of 3,6,9,12-tetraazatetradecane-1,14-diamine (hardener) and cured 15 hours at 60 C.

[0113] The Tg of 75 C., measured via differential scanning calorimetry (DSC model 25 T.A. Instruments, ASTM D 3418) indicated full curing.

Example 4

[0114] 100 parts by weight of liquid isosorbide diglycidyl ether having an epoxide equivalent of 165 was mixed with 21 parts by weight of 1,3-bis(aminomethyl)benzene and cured 15 hours at 60 C.

[0115] The Tg of 74 C., measured via differential scanning calorimetry (ASTM D 3418) indicated full curing.

Example 5

[0116] 100 parts by weight of liquid isosorbide diglycidyl ether having an epoxide equivalent weight of 165 was mixed with 28 parts of 3-aminomethyl-3,5,5-trimethylcyclohexylamine (hardener) and cured 3 hours at 100 C. in order to reach the maximum Tg.

[0117] The Tg of 98 C., measured via differential scanning calorimetry (ASTM D 3418) indicated full curing.

[0118] Water Absorption Test

[0119] The water absorption tests were performed following ASTM D 570. Six specimens having a diameter of 50.8 mm0.3 mm and a thickness of 3.2 mm0.3 mm were cast for each Example and cured 15 hours at 60 C. 3 specimens for each system were immersed in water at room temperature (232 C.) for 24 hours, while the 3 remaining were immersed in hot boiling water for 2 hours. The weight of the specimens was recorded before and after the test. The percentages shown in Table 3 represent the weight variation after the test. A positive value means that the specimen increased its weight. Disgregated means that the specimen broke up during the test.

TABLE-US-00003 TABLE 3 Water absorption (%) Comparative Conditions Example 1 Example 2 Example 3 Example 4 Example 5 2 h at 100 C. +2.1-2.3 +24.2-24.7* disgregated +16.0-16.5* +9.2-9.7 24 h at RT +0.3-0.5 disgregated disgregated disgregated +7.2-7.7 *Specimens become soft and flexible after the test

[0120] Table 3 summarizes the water absorption percentages of comparative Example 1 and of Examples 2 to 5 according to the invention.

[0121] As clearly shown in this Table, Examples 2 to 5 either disgregate or increase substantially their weight when immersed in water.

[0122] The data shown in Table 3 clearly demonstrate that the compositions of the invention are extremely affected by the presence of an aqueous environment. All the Examples showed water diffusion inside the matrix that led either to a breaking or a swelling of the specimens. This property can be exploited in the formulation of a specific isosorbide-based organic matrix for the preparation of sacrificial cores that can be dissolved in water or in aqueous-based solutions.

Example 6

[0123] An epoxy formulation containing 59.3% by weight of liquid isosorbide diglycidyl ether having an epoxide equivalent weight of 165, 40% by weight of fillite, 0.7% by weight of Airex 900 as antifoaming agent was formulated, homogeneized and degassed. Diethyl methyl toluene diamine as a mixture of the two major isomers 3,5-diethyl toluene-2,4-diamine and 3,5-diethyl toluene-2,6-diamine was used as curing agent. 100 parts by weight of isosorbide formulation were mixed with 17 parts by weight of the curing agent and carefully degassed.

[0124] The system was cured 2 hours at 120 C. and 2 hours at 175 C.

[0125] The Tg of 108 C., measured via differential scanning calorimetry (ASTM D 3418) indicated full curing.

Example 7

[0126] Sacrificial Support Preparation and Dissolution Test

[0127] The composition of Example 6 was cast in a cylindrical mould in order to obtain a specimen of 50 mm height29 mm diameter for the solubility test. The composition in the mould was cured 2 hours at 120 C. and 2 hours at 175 C. The Tg of 108 C., measured via differential scanning calorimetry (ASTM D 3418) indicated full curing.

[0128] Dissolution Test

[0129] For the dissolution test, the cylindrical specimen was immersed in a 5% by weight acetic acid solution in water stored at room temperature (232 C.). The sacrificial support showed complete disgregation/dissolution of the organic matrix during 72 hours.

Example 8

[0130] Curable Isosorbide Composition for Dissolution Tests

[0131] An epoxy formulation containing 59.3% by weight of liquid isosorbide diglycidyl ether having an epoxide equivalent weight of 165, 40% by weight of fillite, 0.7% by weight of Airex 900 as antifoaming agent was prepared, homogeneized and degassed. 3-aminomethyl-3,5,5-trimethylcyclohexylamine was used as curing agent. 100 parts by weight of isosorbide formulation were mixed with 17 parts by weight of the curing agent and carefully degassed. The system was cured 3 h at 40 C. and 2 h at 100 C. The Tg of 87 C., measured via differential scanning calorimetry (ASTM D 3418) indicated full curing.

Example 9

[0132] Sacrificial Support Preparation

[0133] The composition of Example 8 was casted in a cylindrical mould in order to obtain a specimen of 50 mm height29 mm diameter. The composition in the mould was cured 3 h at 40 C. and 2 h at 100 C. The Tg of 87 C., measured via differential scanning calorimetry (ASTM D 3418) indicated full curing. After separation of the obtained specimen from the mould, the sacrificial support was then subjected to the deposition of the carbon pre-preg layers and submitted to a curing cycle of 130 C. for 120 minutes and with 6 bar pressure after vacuum bagging.

[0134] Dissolution Test

[0135] To remove the inner sacrificial support, the carbon composite with the sacrificial support inside was immersed in a 5% by weight acetic acid solution in water. After 48-72 hours, the sacrificial core was completely disgregated/dissolved.

[0136] The composite material was isolated without any damages as it can be seen in Table 4, where the properties of the composite material before and after acidic treatment are summarized. In fact, the mechanical properties of the carbon composite were unaltered after the immersion in the solution.

[0137] Composite Mechanical Properties Testing

[0138] In order to evaluate the effect of the acidic solution on the carbon composite, specimens for Interlaminar Shear Strength (ILSS, ASTM D 2344) were prepared and immersed in the acidic solution for 72 h.

TABLE-US-00004 TABLE 4 Property Conditions Composite specimen ILSS short beam 25 C. Pristine 32.4 1.2 strength (MPa) After acidic 32.2 0.9 treatment (72 hours immersion)

Example 10

[0139] An epoxy formulation containing 77.9% by weight of liquid isosorbide diglycidyl ether having an epoxide equivalent weight of 165, 18.8% by weight of hollow glass microspheres, 3.2% of calcium carbonate stearate, 0.1% by weight of Airex 900 as antifoaming agent, was prepared, homogeneized and degassed. 3-aminomethyl-3,5,5-trimethylcyclohexylamine was used as curing agent. 100 parts by weight of isosorbide formulation were mixed with 22 parts by weight of the curing agent and carefully degassed.

[0140] Sacrificial Support Preparation

[0141] The composition of Example 10 was cast in a mould in order to obtain a machinable block with a length of 460 mm, a width of 120 mm and a thickness of 5 mm. The composition in the mould was cured 24 hours at r.t. and postcured 2 h at 100 C. The Tg of 75 C., measured via differential scanning calorimetry (ASTM D 3418) indicated full curing. After separation of the obtained specimen from the mould, the machinable block was submitted to a milling process in order to evaluate the machinability of the system. An excellent machinability was achieved.

[0142] Dissolution Test

[0143] To evaluate the dissolution properties of the machinable block, a parallelepiped of 21*37*35 mm was cut from the main block and immersed in 200 mL of a 5% by weight acetic acid solution in water. By changing the solution every 8-12 hours, the sacrificial core was completely disgregated/dissolved after 28-36 hours.

Example 11

[0144] Foamed Sacrificial Support Preparation

[0145] An epoxy formulation containing 77.5% by weight of liquid isosorbide diglycidyl ether having an epoxide equivalent weight of 165, 18.8% by weight of hollow glass microspheres, 3.2% of calcium carbonate stearate, 0.5% by weight of silicone glycol as blowing agent, was prepared, homogeneized and degassed. A hardener formulation comprising 50% of 1,2-cyclohexanediamine and 50% of the two isomers of 5-diethyl toluene-2,4-diamine and 3,5-diethyl toluene-2,6-diamine was used as curing agent. A polymethylhydrosiloxane was used as blowing agent. 100 parts by weight of isosorbide formulation were mixed with 16 parts by weight of the curing agent and 0.7 part by weight of the blowing agent.

[0146] The composition of Example 11 was cast in a mould in order to obtain a machinable block with a length of 200 mm, a width of 200 mm and a thickness of 2.4 mm. The composition in the mould was cured 8 hours at 80 C. and postcured 6 h at 130 C. The Tg of 108 C., measured via differential scanning calorimetry (ASTM D 3418) indicated full curing. After separation of the obtained specimen from the mould, the machinable block was submitted to a milling process in order to evaluate the machinability of the system. An excellent machinability was achieved.

[0147] Dissolution Test

[0148] To evaluate the dissolution properties of the machinable block, a parallelepiped of 175*125*24 mm was cut from the main block and immersed in 5 L of vinegar. By manual removing the superficial eroded parts of the core every 4-8 hours, the sacrificial support was completely disgregated/dissolved after 18-20 hours.