WO2024141320A1

WO2024141320A1 - Radiation curable liquid composition, process of forming 3d-printed object and 3d-printed object

Info

Publication number: WO2024141320A1
Application number: PCT/EP2023/086502
Authority: WO
Inventors: Wei Zheng FAN; Zhi Zhong CAI; Yan Sheng Li; Jian Hua Fang; Xiao Xia GUO; Zi Qiang LIU
Original assignee: Basf Se; Basf (China) Company Limited
Priority date: 2022-12-29
Filing date: 2023-12-19
Publication date: 2024-07-04

Abstract

The present invention relates to a radiation curable liquid composition comprising a radiation curable hyperbranched polymer containing polyimide moiety, to a process of forming 3D-printed object by using the same, and to a 3D-printed object formed from the same. The radiation curable liquid composition of the present invention has low viscosity and can form a 3D-printed object having excellent mechanical properties and high application temperature.

Description

Radiation curable Liquid composition, process of forming 3D-printed object and 3D-printed object

TECHNICAL FIELD

The present invention relates to a radiation curable liquid composition comprising a radiation curable hyperbranched polymer containing polyimide moiety, to a process of forming 3D-printed object by using the composition, and to a 3D-printed object formed from the composition.

BACKGROUND

3D-printing technologies using curable polymer, e.g., stereolithography (SLA), digital light processing (DLP) or photopolymer jetting (PPJ), have been used in many applications, such as rapid prototyping and rapid manufacturing processes of hearing aids or dental parts. In general, to obtain 3D printed parts, acrylates or epoxies were used for photopolymer resins, which can be UV cured via photo-initiated polymerization during the 3D printing process. Polyimides are a class of high-performance polymers and have found wide applications in industry due to their excellent thermal stability, low-temperature tolerance, outstanding mechanical properties, chemical and radiation resistance, flexible and excellent dielectric properties. It is highly desired to develop high-performance 3D printable photopolymer by introducing polyimide into photopolymer resins. However, most of polyimides cannot be soluble in radiation curable resin, which are main barrier to introduce polyimides into photopolymer resins. Therefore, there’s a strong need to develop a radiation curable liquid composition comprising polyimide for 3D printing.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a radiation curable liquid composition comprising polyimide moiety, which has low viscosity, which can form a 3D-printed object with excellent mechanical properties and high application temperature.

Another object of the present invention is to provide a process of forming 3D-printed object by using the radiation curable liquid composition according to the present invention.

A further object of the present invention is to provide a 3D-printed object formed from the radiation curable liquid composition according to the present invention or obtained by the process according to the present invention. It has been surprisingly found that the above objects can be achieved by following embodiments:

1. A radiation curable liquid composition comprising

(1) At least one radiation curable hyperbranched polymer containing polyimide moiety;

(2) At least one reactive component; and

(3) At least one photo-initiator.

2. The radiation curable liquid composition according to item 1 , wherein the hyperbranched polymer is A_xB_y type, where x is at least 1 and y is at least 2.

3. The radiation curable liquid composition according to item 1 or 2, wherein the radiation curable hyperbranched polymer containing polyimide moiety is a radiation curable hyperbranched polyimide.

4. The radiation curable liquid composition according to item 3, wherein the radiation curable hyperbranched polyimide is derived from dianhydride (a), triamine (b), optional diamine (c) and a compound having one anhydride group and one or more carboxyl group (d), and has a radiation curable group, wherein the dianhydride (a) has the following structure:

wherein Ar is selected from a cycloaliphatic ring having 4 to 8 carbon atoms or a ring system having at least two Ce-Cw aromatic rings; and wherein the triamine (b) has the following structure:

wherein X is a linking group; and each Ri and R2 can be the same or different and independently selected from hydrogen, C1-C6 alkyl, C1-C6 alkoxy, C3-C10 cycloalkyl, C4-C16 cycloalkyl alkyl, C4-C16 alkyl cycloalkyl, C3-C10 cycloalkoxy, C4-C16 cycloalkyl alkoxy, Ce-Cw aryl, C7-C16 arylalkyl, C7-C16 alkylaryl, Ce-Cw aryloxy and 5-10-membered hetaryl. 5. The radiation curable liquid composition according to item 4, wherein Ar is selected from an cycloaliphatic ring with 4 to 8 carbon atoms, or a ring system having at least two Ce-C aromatic rings, preferably Ar is selected from a cycloaliphatic ring with 4 to 8 carbon atoms, or a ring system having 2 to 4 Ce-Cw aromatic rings, preferably the aromatic rings are connected with linking structure Y selected from -O-, -S-, - CO- (carbonyl), -SO2- (sulfonyl), Ci-Ce alkylene, and Ci-Ce alkylene interrupted with one or more heteroatoms or heteroatoms groups selected from -O-, -S-, -CO- (carbonyl) and -SO2- (sulfonyl), wherein one or more hydrogen atoms in the alkylene can be further replaced with F or CF3.

6. The radiation curable liquid composition according to item 4 or 5, wherein Ar is selected from the following group: a cycloaliphatic ring with 4 to 8 carbon atoms;

wherein in the above group means two connecting bonds on the same ring are in the ortho-position of the ring, n is from 0 to 4; and

Y is as defined in item 5.

7. The radiation curable liquid composition according to any of items 4 to 6, wherein each R1 and R2 can be the same or different and independently selected from hydrogen, C1-C4 alkyl, C1-C4 alkoxy, C4-C6 cycloalkyl, C4-C cycloalkyl alkyl, C4-C alkyl cycloalkyl, C5-C10 cycloalkoxy, C5-C10 cycloalkyl alkoxy, Ce-Cw aryl, C7-C14 arylalkyl, C7-C14 alkylaryl and Ce-Cw aryloxy, preferably each R1 and R2 can be the same or different and independently selected from hydrogen, C1-C4 alkyl and phenyl, more preferably one of R1 and R2 on each phenyl is hydrogen.

8. The radiation curable liquid composition according to any of items 4 to 7, wherein X is selected from -O-, -S-, -CO- (carbonyl), -SO2- (sulfonyl), Ci-Ce alkylene, and Ci- Ce alkylene interrupted with one or more heteroatoms or heteroatoms groups selected from -O-, -S-, -CO- (carbonyl) and -SO2- (sulfonyl), preferably selected from -

0-, -S-, -CO- (carbonyl), -SO2- (sulfonyl) and C1-C4 alkylene, most preferably -O-. 9. The radiation curable liquid composition according to any of items 4 to 8, wherein the compound having one anhydride group and one or more carboxyl group (d) has 7 to 16 carbon atoms, preferably selected from 1 ,2,4-benzenetricarboxylic anhydride, 1 ,2,4-naphthalenetricarboxylic anhydride, 1 ,2,4-butanetricarboxylic anhydride, 1 ,2,5- hexanetricarboxylic anhydride, 1 ,2,4-cyclohexanetricarboxylic anhydride, or combination thereof.

10. The radiation curable liquid composition according to any of items 4 to 9, wherein the radiation curable group is selected from an ethylenically unsaturated functional group, an epoxy group, or the mixture thereof.

11. The radiation curable liquid composition according to any of items 4 to 10, wherein the diamine (c) is selected from aliphatic diamine, cycloaliphatic diamine, aromatic diamine, aliphatic-aromatic diamine, cycloaliphatic-aromatic diamine, aliphatic-cycloaliphatic diamine and the combination thereof; preferably the diamine has the formula of NH₂-R^N-NH2, wherein wherein the radical R^N is a hydrocarbyl having 2 to 40 carbon atoms, more preferably having 2 to 30 carbon atoms, for example 2 to 20 or 3 to 20 carbon atoms, preferably R^N is a linear or else cyclic divalent hydrocarbyl, aliphatic or else aromatic divalent hydrocarbyl.

12. The radiation curable liquid composition according to any of items 4 to 11 , wherein the triamine (b) and diamine (c) are primary amines.

13. The radiation curable liquid composition according to any of items 4 to 12, wherein the molar ratio of anhydride groups of dianhydride (a) to total amino groups of triamine (b) and optional diamine (c) is in the range from 0.4:1 to 0.99:1.

14. The radiation curable liquid composition according to any of items 4 to 13, wherein the radiation curable hyperbranched polyimide is formed by reacting dianhydride (a), triamine (b) and optional diamine (c), and capping with compound having one anhydride group and one or more carboxyl group (d) and further grafting with the radiation curable group.

15. The radiation curable liquid composition according to any of items 4 to 14, which has the following building block:

wherein Ri, R₂, X, Ar are as defined in any of items 4 to 14;

Z is a linking group having 1 to 20 carbon atoms, which is optionally interrupted with one or more heteroatoms or heteroatoms groups selected from -O-, -S-, -CO- (carbonyl), -SO2- (sulfonyl) and -(C=O)O-; and

A is a 5-7-membered ring comprising the CO-N-CO moiety or 9-13-membered fused ring comprising the CO-N-CO moiety; each R₃ is the radiation curable group, preferably each R3 is independently selected from an ethylenically unsaturated functional group, an epoxy group, or the mixture thereof.

16. The liquid radiation-curable composition according to any of items 1 to 15, wherein the amount of component (1) is in the range from 0.1 to 50 wt%, preferably from 1 to 40 wt%, based on the total weight of the radiation curable liquid composition.

17. The radiation curable liquid composition according to any of items 1 to 16, wherein the reactive component (2) is a radiation-curable reactive component, preferably comprises at least one oligomer and/or at least one monomer containing at least one radiation curable group selected from an ethylenically unsaturated functional group, an epoxy group, or the mixture thereof. 18. The radiation curable liquid composition according to any of items 1 to 17, wherein the functionality of the reactive component (2) is in the range from 1 to 12, preferably from 1 to 8.

19. The radiation curable liquid composition according to any of items 1 to 18, wherein the amount of the reactive component (2) is in the range from 10 to 99.8 wt.%, preferably from 20 to 99 wt.%, based on the total weight of the radiation curable liquid composition.

20. The radiation curable liquid composition according to any of items 1 to 19, wherein the amount of the photo-initiator (3) is in the range from 0.1 to 10 wt.%, preferably from 0.1 to 5 wt.% or from 0.5 to 5 wt.%, based on the total weight of the radiation curable liquid composition.

21. The radiation curable liquid composition according to any of items 1 to 20, wherein the viscosity of the radiation curable liquid composition is no more than 2000 cps or in the range from 150 to 2000 cps measured according to DIN EN ISO 3219 at 23°C.

22. A process of forming 3D-printed object, comprising using the radiation curable liquid composition according to any of items 1 to 21.

23. The process according to item 22, wherein the process comprises the steps of: (p-i) forming a layer of the radiation curable liquid composition;

(p-ii) applying radiation to cure at least a portion of the layer of the radiation curable liquid composition to form a cured layer;

(p-iii) introducing a new layer of the radiation curable liquid composition onto the cured layer;

(p-iv) applying radiation to the new layer of the radiation curable liquid composition to form a new cured layer; and

(p-v) repeating steps (iii) and (iv) until the 3D object is manufactured.

24. A 3D-printed object formed from the radiation curable liquid composition according to any of items 1 to 21 or obtained by the process according to any of item 22 or 23.

25. Use of the radiation curable liquid composition according to any of items 1 to 21 in 3D-printing. The radiation curable liquid composition of the present invention has low viscosity and can form a 3D-printed object having excellent mechanical properties and high application temperature and high thermal stability.

DESCRIPTION OF THE DRAWINGS

Figure 1 shows photograph of the 3D-printed object obtained from example 1 B.

Figure 2 shows 1 H NMR spectrum of the synthesized PI-1 (in DMSO-d6).

Figure 3 shows 1 H NMR spectrum of the synthesized PI-2 (in DMSO-d6).

Figure 4 shows 1 H NMR spectrum of the synthesized PI-3 (in DMSO-d6).

Figure 5 shows 1 H NMR spectrum of the synthesized PI-4 (in DMSO-d6).

DETAILED DESCRIPTION OF THE INVENTION

Unless defined otherwise, all technical and scientific terms used herein have the meaning commonly understood by a person skilled in the art to which the invention belongs. As used herein, the following terms have the meanings ascribed to them below, unless specified otherwise.

The articles “a”, “an” and “the” mean one or more of the species designated by the term following said article.

In the context of the present disclosure, any specific values mentioned for a feature (comprising the specific values mentioned in a range as the end point) can be recombined to form a new range.

Further embodiments of the present invention are discernible from the claims, the description, the examples, and the drawings. It will be understood that the aforementioned and hereinbelow still to be elucidated features of the subject matter of the present invention are utilizable not only in the particular combination indicated, but also in other combinations without leaving the realm of the present invention.

One aspect of the present invention relates to a radiation curable liquid composition comprising

(2) At least one reactive component; and

(3) At least one photoinitiator. So-called AB_X, preferably AB2 or AB3, monomers can be used for the synthesis of the hyperbranched polymers. These have two different functional groups A and B in a molecule, which can undergo an intermolecular reaction with one another with formation of a link. The functional group A is comprised only once per molecule and the functional group B twice or more. The reaction of said AB_X monomers with one another results in the formation of uncrosslinked polymers having regularly arranged branching points. The polymers have virtually exclusively B groups at the chain ends.

Furthermore, hyperbranched polymers can be prepared via the A_x + B_y synthesis route. Here, A_x and B_y are two different monomers having the functional groups A and B and the indices x and y for the number of functional groups per monomer. In the case of the A_x + B_y synthesis, presented here by way of example for an A2 + B3 synthesis, a difunctional monomer A₂ is reacted with a trifunctional monomer B3. A 1 :1 adduct of A and B having on average one functional group A and two functional groups B first forms and can then likewise react to give a hyperbranched polymer. The hyperbranched polymers thus obtained also have predominantly B groups as terminal groups.

In an embodiment, the hyperbranched polymer is A_xB_y type, where x is at least 1 or at least 2 and y is at least 2 or at least 3.

According to the present invention, the radiation curable hyperbranched polymer containing polyimide moiety as component (1) comprises a radiation curable group, preferably selected from an ethylenically unsaturated functional group, an epoxy group, or the mixture thereof.

In an embodiment, the radiation curable hyperbranched polymer containing polyimide moiety is a radiation curable hyperbranched polyimide, for example a radiation curable hyperbranched polyimide of A_xB_y type, where x is at least 1 or at least 2 and y is at least 2 or at least 3. The radiation curable hyperbranched polyimide comprises a radiation curable group, preferably selected from an ethylenically unsaturated functional group, an epoxy group, or the mixture thereof.

In this context, functional group A can be anhydride group and functional group B can be amino, vice versa. In an embodiment, the radiation curable hyperbranched polyimide is a radiation curable hyperbranched polyimide of A_xB_y type, where x is at least 2 and y is at least 3.

In an embodiment, Ax is a dianhydride and B_y is a triamine. Details of the dianhydride are as described below for dianhydride (a) and details of the triamine are as described below for triamine (c).

In an embodiment, the radiation curable hyperbranched polyimide is derived from dianhydride (a), triamine (b), optional diamine (c) and a compound having one anhydride group and one or more carboxyl group (d), and has a radiation curable group, wherein the dianhydride (a) has the following structure:

wherein X is a linking group; each Ri and R2 can be the same or different and independently selected from hydrogen, C1-C6 alkyl, C1-C6 alkoxy, C3-C10 cycloalkyl, C4-C16 cycloalkyl alkyl, C4-C16 alkyl cycloalkyl, C3-C10 cycloalkoxy, C4-C16 cycloalkyl alkoxy, Ce-Cw aryl, C7-C16 arylalkyl, C7-C16 alkylaryl, Ce-Cw aryloxy and 5-10-membered hetaryl.

The term "C_n-C_m alkyl" as used herein (and also in C_n-C_m alkoxy) refers to a branched or unbranched saturated hydrocarbon group having n to m, e.g. 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, for example methyl, ethyl, propyl, 1-meth- ylethyl, butyl, 1 -methylpropyl, 2-methylpropyl, 1 , 1-dimethylethyl, pentyl, 1-methyl- butyl, 2-methylbutyl, 3-methylbutyl, 2,2-dimethylpropyl, 1 -ethylpropyl, hexyl, 1 ,1-di- methylpropyl, 1 ,2-dimethylpropyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 4- methylpentyl, 1 , 1-dimethylbutyl, 1 ,2-dimethylbutyl, 1 ,3-dimethylbutyl, 2,2-dimethyl- butyl, 2,3-dimethylbutyl, 3,3-dimethylbutyl, 1-ethylbutyl, 2-ethylbutyl, 1 ,1 ,2-trime- thylpropyl, 1 ,2,2-trimethylpropyl, 1-ethyl-1-methylpropyl, 1-ethyl-2-methylpropyl and their isomers. Ci-C4-alkyl means for example methyl, ethyl, propyl, 1 -methylethyl, butyl, 1-methylpropyl, 2-methylpropyl or 1 ,1 -dimethylethyl.

Similarly, "C_n-C_m alkoxy" refer to straight-chain or branched alkyl groups having n to m carbon atoms, e.g., 1 to 6, in particular 1 to 4 carbon atoms (as mentioned above) bonded through oxygen at any bond in the alkyl group. Examples include C1-C4- alkoxy such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, sec-butoxy, isobutoxy and tert- butoxy.

The term "C3-C_m cycloalkyl" as used herein refers to a monocyclic ring of 3- to m- membered, for example 3- to 10-membered, preferably 4- to 10-membered, such as 4- to 7-membered saturated cycloaliphatic radicals, e.g., cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl and cyclodecyl.

The term "aryl" as used herein refers to a mono-, bi- or tricyclic aromatic hydrocarbon radical such as phenyl or naphthyl, in particular phenyl (also referred as to CeHs as substituent).

The term "hetaryl" includes monocyclic 5- or 6-membered heteroaromatic radicals comprising as ring members 1 , 2, 3, or 4 heteroatoms selected from N, O and S. Examples of 5- or 6-membered heteroaromatic radicals include pyridyl, i.e. 2-, 3-, or 4-pyridyl, pyrimidinyl, i.e. 2-, 4-, or 5-pyrimidinyl, pyrazinyl, pyridazinyl, i.e. 3- or 4-pyridazinyl, thienyl, i.e. 2- or 3-thienyl, furyl, i.e. 2-or 3-furyl, pyrrolyl, i.e. 2- or 3-pyr- rolyl, oxazolyl, i.e. 2-, 3-, or 5-oxazolyl, isoxazolyl, i.e. 3-, 4-, or 5-isoxazolyl, thiazolyl, i.e. 2-, 3- or 5-thiazolyl, isothiazolyl, i.e. 3-, 4-, or 5-isothiazolyl, pyrazolyl, i.e. 1-, 3-, 4-, or 5-pyrazolyl, i.e. 1-, 2-, 4-, or 5-imidazolyl, oxadiazolyl, e.g. 2- or 5-[1 ,3,4]oxadia- zolyl, 4- or 5-(1 ,2,3-oxadiazol)yl, 3- or 5-(1 ,2,4-oxadiazol)yl, 2- or 5-(1 ,3,4-thiadia- zol)yl, thiadiazolyl, e.g. 2- or 5-(1 ,3,4-thiadiazol)yl, 4- or 5-(1 ,2,3-thiadiazol)yl, 3- or 5- (1 ,2,4-thiadiazol)yl, triazolyl, e.g. 1 H-, 2H- or 3H-1 ,2,3-triazol-4-yl, 2H-triazol-3-yl, 1 H-, 2H-, or 4H-1 ,2,4-triazolyl and tetrazolyl, i.e. 1 H- or 2H-tetrazolyl. The term "hetaryl" also includes bicyclic 8 to 10-membered heteroaromatic radicals comprising as ring members 1 , 2 or 3 heteroatoms selected from N, O and S, wherein a 5- or 6- membered heteroaromatic ring is fused to a phenyl ring or to a 5- or 6-membered heteroaromatic radical. Examples of a 5- or 6-membered heteroaromatic ring fused to a phenyl ring or to a 5- or 6-membered heteroaromatic radical include benzo- furanyl, benzothienyl, indolyl, indazolyl, benzimidazolyl, benzoxathiazolyl, benzoxadi- azolyl, benzothiadiazolyl, benzoxazinyl, chinolinyl, isochinolinyl, purinyl, 1 ,8-naphthy- ridyl, pteridyl, pyrido[3,2-d]pyrimidyl or pyridoimidazolyl and the like.

Dianhydride (a)

According to the present invention, the dianhydride (a) has the following structure:

wherein Ar is selected from a cycloaliphatic ring having 4 to 8 carbon atoms or a ring system having at least two Ce-Cw aromatic rings.

In an embodiment, Ar is selected from an cycloaliphatic ring with 4 to 8 carbon atoms, or a ring system having at least two Ce-Cw aromatic rings, preferably Ar is selected from a cycloaliphatic ring with 4 to 8 carbon atoms, or a ring system having 2 to 4 Ce-Cw aromatic rings, preferably the aromatic rings are connected with linking structure Y selected from direct bond, -O-, -S-, -CO- (carbonyl), -SO2- (sulfonyl), C1- Ce alkylene, and Ci-Ce alkylene interrupted with one or more heteroatoms or heteroatoms groups selected from -O-, -S-, -CO- (carbonyl) and -SO2- (sulfonyl), wherein one or more hydrogen atoms in the alkylene can be further replaced with F or CF3; preferably Y is selected from direct bond, -O-, -S-, -CO- (carbonyl), -SO2- (sulfonyl), C1-C4 alkylene (for example C1-C2 alkylene), and C1-C4 alkylene interrupted with one or more heteroatoms or heteroatoms groups selected from -O-, -S-, -CO- (carbonyl) and -SO2- (sulfonyl), wherein one or more hydrogen atoms in the alkylene can be further replaced with F or CF₃;

In a preferred embodiment, Ar is selected from the following group: a cycloaliphatic ring with 4 to 8 carbon atoms, for example 4, 5, 6, 7 or 8 carbon atoms;

wherein

in the above group means two connecting bonds on the same ring are in the ortho-position of the ring, n is from 0 to 4, preferably from 0 to 2; and

Y is as defined above. In a preferred embodiment, the group of formula (III) as Ar is selected from following groups:

wherein Y is as defined above.

In a preferred embodiment, Ar is selected from the following group:

According to the present invention, one or two or more dianhydride (a) can be used.

Specific examples of dianhydride (a) can include, for example, 4,4'-hexafluoroiso- propylidene diphthalic anhydride (6FDA), 3,3’,4,4’-biphenyltetracarboxylic dianhydride (BPDA), 4,4-oxydiphthalic dianhydride (ODPA), 4,4’-sulfonyl diphthalic anhydride (S02DPA), 4,4’-(isopropylidenebis(4,1-phenylene)bis(oxy)) bis(phthalic anhydride) (6HDBA), 4-(2,5-dioxotetrahydrofuran-3-yl)-1 ,2,3,4-tetrahydronaphthalene-1 ,2- dicarboxylic dianhydride (TDA), 4,4’-(thiobis(4,1-phenylene)bis(oxy)) bis(phthalic anhydride) (BDSDA), 1 ,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), bicy- clo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BTA), bicyclooctene-2, 3,5,6- tetracarboxylic dianhydride (BODA), 1 ,2,3,4-cyclopentanetetracarboxylic dianhydride (CPDA), 1 , 2, 4, 5-cyclohexanetetracarboxylic dianhydride (CHDA), 1 ,2,4-tricarboxy -3- methylcarboxycyclopentane dianhydride (TMDA), 1 ,2,3,4-tetracarboxycyclopentane dianhydride (TCDA), and mixture thereof.

Triamine (b)

According to the present invention, the triamine (b) has the following structure:

wherein X is a linking group; and each Ri and R2 can be the same or different and independently selected from hydrogen, C1-C6 alkyl, C1-C6 alkoxy, C3-C10 cycloalkyl, C4-C16 cycloalkyl alkyl, C4-C16 alkyl cycloalkyl, C3-C10 cycloalkoxy, C4-C16 cycloalkyl alkoxy, Ce-Cw aryl, C7-C16 arylalkyl, C7-C16 alkylaryl, Ce-Cw aryloxy and 5-10-membered hetaryl.

In a preferred embodiment, each R1 and R2 can be the same or different and independently selected from hydrogen, C1-C4 alkyl, C1-C4 alkoxy, C4-C6 cycloalkyl, C4-C cycloalkyl alkyl, C4-C alkyl cycloalkyl, Cs-C cycloalkoxy, Cs-C cycloalkyl alkoxy, Ce-Cw aryl, C7-C14 arylalkyl, C7-C14 alkylaryl and Ce-Cw aryloxy, preferably each R1 and R2 can be the same or different and independently selected from hydrogen, Ci- 04 alkyl and phenyl.

In a preferred embodiment, one of R1 and R2 on each phenyl is hydrogen. In an embodiment, each R1 is H and each R2 is C1-C4 alkyl.

According to the present invention, X is selected from -O-, -S-, -CO- (carbonyl), -SO2- (sulfonyl), Ci-Ce alkylene, and Ci-Ce alkylene interrupted with one or more heteroatoms or heteroatoms groups selected from -O-, -S-, -CO- (carbonyl) and -SO2- (sulfonyl), preferably selected from -O-, -S-, -CO- (carbonyl), -SO2- (sulfonyl), C1-C4 alkylene and C1-C4 alkylene interrupted with one or more heteroatoms or heteroatoms groups selected from -O-, -S-, -CO- (carbonyl) and -SO₂- (sulfonyl). In a preferred embodiment, X is -O- or -S-, more preferably X is -O-.

In an embodiment, the variables in triamine (b) of formula (II) have the following definitions: wherein X is selected from -O-, -S-, -CO- (carbonyl), -SO2- (sulfonyl), C1-C4 alkylene and C1-C4 alkylene interrupted with one or more heteroatoms or heteroatoms groups selected from -O-, -S-, -CO- (carbonyl) and -SO2- (sulfonyl); and each R1 and R2 can be the same or different and independently selected from hydrogen, C1-C4 alkyl, C1-C4 alkoxy, C4-C6 cycloalkyl, C4-C10 cycloalkyl alkyl, C4-C10 alkyl cycloalkyl, C5-C10 cycloalkoxy, C5-C10 cycloalkyl alkoxy, Ce-Cw aryl, C7-C14 arylalkyl, C7-C14 alkylaryl and Ce-Cw aryloxy.

In an embodiment, the variables in triamine (b) of formula (II) have the following definitions: wherein X is selected from selected from -O-, -S-, -CO- (carbonyl) and -SO2- (sulfonyl); and each R1 and R2 can be the same or different and independently selected from hydrogen, C1-C4 alkyl and phenyl.

In an embodiment, the variables in triamine (b) of formula (II) have the following definitions: wherein X is -O- or -S-, more preferably X is -O-; and one of R1 and R2 on each phenyl is hydrogen and the other is C1-C4 alkyl.

In an embodiment, the triamine (b) has the following structure:

wherein X, Ri and R2 are as defined above.

In an embodiment, the triamine (b) has the following structure:

wherein X, R1 and R2 are as defined above.

Specific example of triamine (b) can include, for example the following compound (TAMPB):

According to the present invention, one or two or more triamine (b) can be used.

Diamine (c)

According to the present invention, diamine (c) can also be used in addition to triamine (b).

Diamine (c) may be selected from any organic compound having two amino groups per molecule.

In an embodiment, the diamine (c) is selected from aliphatic diamine, cycloaliphatic diamine, aromatic diamine, aliphatic-aromatic diamine, cycloaliphatic-aromatic dia- mine, aliphatic-cycloaliphatic diamine and the combination thereof. In a preferred embodiment, diamine (c) has 2 to 40 carbon atoms, more preferably having 2 to 30 carbon atoms, for example 2 to 20, 3 to 20, 4 to 20 or 6 to 12 carbon atoms.

In a preferred embodiment, the diamine has the formula of NH2-R^N-NH2, wherein the radical R^N is a hydrocarbyl having 2 to 40 carbon atoms, more preferably having 2 to 30 carbon atoms, for example 2 to 20, 3 to 20, 4 to 20 or 6 to 12 carbon atoms. R^N can be a linear or else cyclic divalent hydrocarbyl, aliphatic or else aromatic divalent hydrocarbyl. In an embodiment, R^N is a linear divalent hydrocarbyl, a cyclic divalent hydrocarbyl, an aliphatic divalent hydrocarbyl, or an aromatic divalent hydrocarbyl.

Specific example of diamine (c) can include, for example, ethylenediamine, propylenediamines (1 ,2-diaminopropane and 1 ,3-diaminopropane), tetramethylenediamine (1 ,4-diaminobutane), 1 ,5-diaminopentane, 1 ,3-diamino-2,2-diethylpropane, 1 ,3- bis(methylamino)propane, hexamethylenediamine (1 ,6-diaminohexane), heptanediamine, octanediamine, nonanediamine, decanediamine, dodecanediamine, hexadecanediamine, tolylenediamine, xylylenediamine, diaminodiphenylmethane, diaminodicyclohexylmethane, phenylenediamine, cyclohexylenediamine, bis(aminomethyl)cy- clohexane, 1 ,5-diamino-2-methylpentane, 3-(propylamino)propylamine, isophoronediamine (IPDA), 3(or 4),8(or 9)-bis(aminomethyl)-tricyclo[5.2.1.0²’⁶]decane isomer mixtures, 2-butyl-2-ethyl-1 ,5-pentamethylenediamine, 2,2,4- or 2,4,4-trimethyl-1 ,6-hexa- methylenediamine, 2-aminopropylcyclohexylamine, 3(4)-aminomethyl-1-methylcyclo- hexylamine, 1 ,4-diamino-4-methylpentane and 2,4,6-trimethyl-1 ,3-phenylenediamine.

The molar ratio of triamine (b) to diamine (c) can be at least 1 :10, preferably at least 1 :8, more preferably at least 1 :6, for example 1 :4, 1 :2, 1 : 1 , 2: 1 , 4: 1 , 6: 1 , 8: 1 or 10: 1. In an embodiment, the molar ratio of triamine (b) to diamine (c) can be in the range from 1 :10 to 10:1 , from 1 :8 to 8:1 , or from 1 :6 to 8:1.

According to the present invention, the triamine (b) is primary amine. According to the present invention, diamine (c) is primary amine.

According to the present invention, the molar ratio of anhydride groups of dianhydride (a) to total amino groups of triamine (b) and optional diamine (c) is in the range from 0.4:1 to 0.99:1 (for example 0.42:1 , 0.45:1 , 0.48:1 , 0.5:1 , 0.6:1 , 0.7:1 , 0.8:1 , 0.9:1 , or 0.95:1), preferably from 0.45:1 to 0.95:1. Compound having one anhydride group and one or more carboxyl group (d)

In an embodiment, the compound having one anhydride group and one or more carboxyl group (d) has 7 to 16 carbon atoms, for example 7, 8, 9, 10, 11 , 12, 13, 14, 15 or 16 carbon atoms. The compound having one anhydride group and one or more carboxyl group (d) can be aliphatic, cycloaliphatic or aromatic.

Specific example of the compound having one anhydride group and one or more carboxyl group (d) can include, for example, 1 ,2,4-benzenetricarboxylic anhydride (Trimellitic anhydride), 1 ,2,4-naphthalenetricarboxylic anhydride, 1 ,2,4-butanetricar- boxylic anhydride, 1 ,2,5-hexanetricarboxylic anhydride, 1 ,2,4-cyclohexanetricarbox- ylic anhydride, or combination thereof.

Compound having one anhydride group (e)

In addition to compound (d), the compound having one anhydride group (e) can be further used. In a preferred embodiment, compound (e) has 4 to 16 carbon atoms, for example 4, 6, 8, 10, 12, 14 or 16 carbon atoms. Compound (e) can be aliphatic, cycloaliphatic or aromatic.

In an embodiment, compound (e) has a carbon-carbon unsaturated bond.

Specific examples of compound having one anhydride group (e) can include for example maleic anhydride, itaconic anhydride, citraconic anhydride, and methylene malonic anhydride, more preferably maleic anhydride.

A person skilled in the art could understand that compound (e) is different from compound (d). In this regard, compound (e) does not contain the carboxyl group.

If compound (e) is used, the molar ratio of compound (d) to compound (e) can be at least 1 :5, preferably at least 1 :3, more preferably at least 1 :2, for example 1 :1 , 2:1 , 4:1 , 6:1 , 8:1 or 10:1. In an embodiment, the molar ratio of triamine (b) to diamine (c) can be in the range from 1 :5 to 10:1 , from 1 :3 to 8:1 or from 1 :2 to 8:1.

Radiation curable group and compound (f)

According to the present invention, the radiation curable hyperbranched polyimide has a radiation curable group. The radiation curable group can be selected from an ethylenically unsaturated functional group, an epoxy group, or the mixture thereof. In an embodiment, the ethylenically unsaturated functional group contains a carboncarbon unsaturated bond, such as those found in the following functional groups: allyl, vinyl, acrylate, methacrylate, acryloxy, methacryloxy, acrylamido, methacrylamido, acetylenyl, maleimido, and the like; preferably, the ethylenically unsaturated functional group contains a carbon-carbon unsaturated double bond.

The radiation curable group can be connected to the remainder of the hyperbranched polyimide via a linking group Z. In an embodiment, the linking group Z has 1 to 20 carbon atoms, or 2 to 16, or 3 to 12 carbon atoms. The linking group Z optionally has one or more heteroatoms or heteroatoms groups selected from -O-, -S-, -CO- (carbonyl), -SO2- (sulfonyl) and -(C=O)O-.

According to the present invention, the number of the radiation curable groups can be in the range from 0.05 to 1 (for example 0.06, 0.08, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 or 0.9) per unit formed from the triamine (b) in the radiation curable hyperbranched polyimide.

The radiation curable group can be derived from compound (f) containing the radiation curable group and a functional group reactive to the carboxyl. In an embodiment, a compound (f) containing the radiation curable group and a functional group reactive to the carboxyl, such as hydroxy can be used. In an embodiment, compound (f) containing the radiation curable group and a functional group reactive to the carboxyl is a hydroxy-functional ethylenically unsaturated monomer, such as hydroxy-functional (meth)acrylate or hydroxy-functional (meth)acrylamide or mixture thereof, more preferably hydroxy-functional (meth)acrylate.

Specific example of hydroxy-functional (meth)acrylate can include for example Ci to C10 hydroxyalkyl (meth)acrylate, such as such as C2 to Cs hydroxyalkyl (meth)acry- late can include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hy- droxypropyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, or 3-hydroxy-2-ethylhexyl (meth)acry- late etc.

In an embodiment, the radiation curable hyperbranched polyimide is derived from dianhydride (a), triamine (b), and a compound having one anhydride group and one or more carboxyl group (d), and has a radiation curable group, wherein dianhydride (a), triamine (b), compound (d) and the radiation curable group are as defined above. In an embodiment, the radiation curable hyperbranched polyimide is derived from dianhydride (a), triamine (b), diamine (c) and a compound having one anhydride group and one or more carboxyl group (d), and has a radiation curable group, wherein dianhydride (a), triamine (b), diamine (c), compound (d) and the radiation curable group are as defined above.

In an embodiment, the radiation curable hyperbranched polyimide is derived from dianhydride (a), triamine (b), a compound having one anhydride group and one or more carboxyl group (d) and compound (e), and has a radiation curable group, wherein dianhydride (a), triamine (b), compound (d), compound (e) and the radiation curable group are as defined above.

In an embodiment, the radiation curable hyperbranched polyimide is derived from dianhydride (a), triamine (b), diamine (c), a compound having one anhydride group and one or more carboxyl group (d) and compound (e), and has a radiation curable group, wherein dianhydride (a), triamine (b), diamine (c), compound (d), compound (e) and the radiation curable group are as defined above.

In an embodiment, the radiation curable hyperbranched polyimide is derived from dianhydride (a), triamine (b), optional diamine (c), a compound having one anhydride group and one or more carboxyl group (d), optional compound (e), and compound (f), wherein dianhydride (a), triamine (b), diamine (c), compound (d), compound (e) and compound (f) are as defined above.

In an embodiment, the radiation curable hyperbranched polyimide is derived from dianhydride (a), triamine (b), a compound having one anhydride group and one or more carboxyl group (d), and compound (f), wherein dianhydride (a), triamine (b), compound (d), and compound (f) are as defined above.

In a preferred embodiment, the radiation curable hyperbranched polyimide of the present invention has the following building block:

(IV) wherein R1, R2, X, Ar are as defined above;

A is a 5-7-membered ring comprising the CO-N-CO moiety or 9 to 13-membered fused ring comprising the CO-N-CO moiety; each R₃ is the radiation curable group, preferably each R3 is independently selected from an ethylenically unsaturated functional group, an epoxy group, or the mixture thereof.

In formula (IV), * denotes the bond to the remainder of the molecule.

In an embodiment, the linking group Z has 1 to 20 carbon atoms, or 2 to 16, or 3 to 12 carbon atoms, which is optionally interrupted with one or more heteroatoms or heteroatoms groups selected from -O-, -S-, -CO- (carbonyl), -SO2- (sulfonyl) and - (C=O)O-.

In an embodiment, A is a 5-7-membered ring having the CO-N-CO moiety and the remaining ring members are carbon atoms; or A is a 9-13-membered fused ring comprising the CO-N-CO moiety and the remaining ring members are carbon atoms. In an embodiment, the ring A has the following structure:

As mentioned above, the ethylenically unsaturated functional group contains a carbon-carbon unsaturated bond, such as those found in the following functional groups: allyl, vinyl, acrylate, methacrylate, acryloxy, methacryloxy, acrylamido, methacrylamido, acetylenyl, maleimido, and the like, especially acrylate and methacrylate.

In a preferred embodiment, the radiation curable hyperbranched polyimide of the present invention can be formed by reacting dianhydride (a), triamine (b) and optional diamine (c), and capping with compound having one anhydride group and one or more carboxyl group (d) and further grafting with the radiation curable group.

In a preferred embodiment, the radiation curable hyperbranched polyimide of the present invention can be formed by reacting dianhydride (a), triamine (b) and optional diamine (c), and capping with compound having one anhydride group and one or more carboxyl group (d) and optional compound having one anhydride group (e) and further grafting with the radiation curable group.

In a preferred embodiment, the radiation curable hyperbranched polyimide of the present invention can be formed by reacting dianhydride (a), triamine (b) and optional diamine (c), and capping with compound having one anhydride group and one or more carboxyl group (d) and optional compound having one anhydride group (e) and further reacted with compound (f).

In a preferred embodiment, the radiation curable hyperbranched polyimide of the present invention can be formed by reacting dianhydride (a) and triamine (b), and capping with compound having one anhydride group and one or more carboxyl group (d) and further reacted with compound (f).

The radiation curable hyperbranched polyimide can be prepared by a process comprising (i) reacting dianhydride (a) with triamine (b) and optional diamine (c) to obtain an amine-terminated hyperbranched polyamic acid;

(ii) capping the amine-terminated hyperbranched polyamic acid obtained in step (i) with the compound having one anhydride group and one or more carboxyl group (d);

(iii) imidization of the product obtained in step (ii); and

(iv) grafting the imidization product obtained in step (iii) with the radiation curable group, preferably by reacting the imidization product obtained in step (iii) with compound (f).

According to the present invention, the amount of component (1) can be in the range from 0.1 to 50 wt.% (for example 0.1 wt.%, 0.2 wt.%, 0.5 wt.%, 0.8 wt.%, 1 wt.%, 1.5 wt.%, 2 wt.%, 3 wt.%, 5 wt.%, 8 wt.%, 10 wt.%, 12 wt.%, 15 wt.%, 18 wt.%, 20 wt.%, 22 wt.%, 25 wt.%, 28 wt.%, 30 wt.%, 35 wt.%, 40 wt.%, 45 wt.%, or 50 wt.%), preferably from 1 to 40 wt.% or 2 to 35 wt.%, or 3 to 35 wt.%, or 4 to 35 wt.%, or 5 to 35 wt.%, or 1 to 30 wt.%, or 2 to 30 wt.%, or 3 to 30 wt.%, or 4 to 30 wt.%, or 5 to 30 wt.%, or 1 to 22 wt.%, or 2 to 22 wt.%, or 4 to 22 wt.%, or 1 to 20 wt.%, or 2 to 20 wt.%, or 3 to 20 wt.%, or 4 to 20 wt.%, or 5 to 20 wt.%, or 1 to 18 wt.%, or 2 to 18 wt.%, or 3 to 18 wt.%, or 4 to 18 wt.%, or 5 to 18 wt.%, based on the total weight of the radiation curable liquid composition of the present invention.

Component (2): Reactive component

The curable composition of the present invention comprises at least one reactive component as component (2). Generally, reactive components usable for 3D-printing may be used in the present invention as reactive component (2). Reactive component (2) of the present invention contains at least one radiation curable group.

In an embodiment of the present invention, reactive component (2) of the present invention comprises a monomer and /or oligomer containing at least one radiation curable group.

The radiation curable group of reactive component (2) of the present invention may be selected from the group consisting of an ethylenically unsaturated functional group, an epoxy group, or the mixture thereof. For example, the at least one radiation curable group of the monomer and /or oligomer containing at least one radiation curable group suitable as reactive component (2) is selected from the group consisting of an ethylenically unsaturated functional group, an epoxy group, or the mixture thereof. In an embodiment, the radiation curable group of component (1) and component (2) is an ethylenically unsaturated functional group, or the radiation curable group of component (1) and component (2) is an epoxy group.

Preferably, the number of the radiation curable group in reactive component (2) is in the range from 1 to 12, preferably from 1 to 10, such as from 1 to 8, per molecule of reactive component (2).

As reactive component (2) containing at least one epoxy group, non-limiting examples may include epoxidized olefins, aromatic glycidyl ethers, aliphatic glycidyl ethers, or the combination thereof, preferably aromatic or aliphatic glycidyl ethers.

Examples of possible epoxidized olefins include epoxidized C2-C -olefins, such as ethylene oxide, propylene oxide, iso-butylene oxide, 1 -butene oxide, 2-butene oxide, vinyloxirane, styrene oxide or epichlorohydrin, preference being given to ethylene oxide, propylene oxide, isobutylene oxide, vinyloxirane, styrene oxide or epichlorohydrin, particular preference to ethylene oxide, propylene oxide or epichlorohydrin, and very particular preference to ethylene oxide and epichlorohydrin.

Aromatic glycidyl ethers are, for example, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol B diglycidyl ether, bisphenol S diglycidyl ether, hydroquinone diglycidyl ether, alkylation products of phenol/dicyclopentadiene, e.g., 2,5-bis[(2,3-epoxypropoxy)phenyl]octahydro-4,7-methano-5H-indene (CAS No. [13446-85-0]), tris[4-(2,3-epoxypropoxy)phenyl]methane isomers (CAS No. [66072- 39-7]), phenol-based epoxy novolaks (CAS No. [9003-35-4]), and cresol-based epoxy novolaks (CAS No. [37382-79-9]).

Examples of aliphatic glycidyl ethers include 1 ,4-butanediol diglycidyl ether, 1 ,6- hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, 1 ,1 ,2,2-tetrakis[4-(2,3-epoxypropoxy)phenyl]ethane (CAS No. [27043-37-4]), diglycidyl ether of polypropylene glycol (a,w-bis(2,3- epoxypropoxy)poly(oxypropylene), CAS No. [16096-30-3]) and of hydrogenated bisphenol A (2,2-bis[4-(2,3-epoxypropoxy)cyclohexyl]propane, CAS No. [13410-58- 7]).

More preferably, reactive component (2) of the present invention contains at least one ethylenically unsaturated functional group. In an embodiment of the invention, the ethylenically unsaturated functional group contains a carbon-carbon unsaturated bond, such as those found in the following functional groups: allyl, vinyl, acrylate, methacrylate, acryloxy, methacryloxy, acrylamido, methacrylamido, acetylenyl, maleimido, and the like; preferably, the ethylenically unsaturated functional group contains a carbon-carbon unsaturated double bond. More preferably, the ethylenically unsaturated functional group contains a carbon-carbon unsaturated double bond, such as those found in the following functional groups: acrylate and methacrylate.

In a preferred embodiment of the invention, reactive component (2) of the present invention contains, in addition to the ethylenically unsaturated functional group and/or epoxy group, urethane groups, ether groups, ester groups, carbonate groups, and any combination thereof.

As reactive component (2) of the present invention, the oligomer containing at least one radiation curable group includes, for example, oligomers containing a core structure linked to the ethylenically unsaturated functional group, optionally via a linking group. The linking group can be an ether, ester, amide, urethane, carbonate, or carbonate group. In some instances, the linking group is part of the ethylenically unsaturated functional group, for instance an acryloxy or acrylamido group. The core group can be an alkyl (straight and branched chain alkyl groups), aryl (e.g. phenyl), polyether, polyester, siloxane, urethane, or other core structures and oligomers thereof. Suitable ethylenically unsaturated functional group may comprise groups containing carbon-carbon double bond, such as methacrylate groups, acrylate groups, vinyl ether groups, allyl ether groups, acrylamide groups, methacrylamide groups, or a combination thereof. In some embodiments, suitable oligomers comprise mono- and/or polyfunctional acrylate, such as mono (meth)acrylate, di(meth)acrylate, tri(meth)acrylate, or higher, or combination thereof. Optionally, the oligomer may include a siloxane backbone in order to further improve cure, flexibility and/or additional properties of the radiation-curable composition for 3D printing.

In some embodiments, the oligomer containing at least one ethylenically unsaturated functional group can be selected from the following classes: urethane (i.e. an urethane-based oligomer containing ethylenically unsaturated functional group), polyether (i.e. an polyether-based oligomer containing ethylenically unsaturated functional group), polyester (i.e. an polyester-based oligomer containing ethylenically unsaturated functional group), polycarbonate (i.e. an polycarbonate-based oligomer containing ethylenically unsaturated functional group), polyestercarbonate (i.e. an polyestercarbonate-based oligomer containing ethylenically unsaturated functional group), epoxy (i.e. an epoxy-based oligomer containing ethylenically unsaturated functional group), silicone (i.e. a silicone-based oligomer containing ethylenically unsaturated functional group) or any combination thereof. Preferably, the oligomer containing at least one ethylenically unsaturated functional group can be selected from the following classes: a urethane-based oligomer, an epoxy-based oligomer, a polyester-based oligomer, a polyether-based oligomer, polyether urethane-based oligomer, polyester urethane-based oligomer or a silicone-based oligomer, as well as any combination thereof.

In a preferred embodiment of the invention, the oligomer containing at least one ethylenically unsaturated functional group comprises a urethane-based oligomer comprising urethane repeating units and one, two or more ethylenically unsaturated functional groups, for example those containing carbon-carbon unsaturated double bond, such as (meth)acrylate groups, (meth)acrylamide groups, allyl groups and vinyl groups. Preferably, the oligomer contains at least one urethane linkage (for example, one, two or more urethane linkages) within the backbone of the oligomer molecule and at least one acrylate and/or methacrylate functional groups (for example, one, two or more acrylate and/or methacrylate functional groups) pendent to the oligomer molecule. In some embodiments, aliphatic, cycloaliphatic, or mixed aliphatic and cycloaliphatic urethane repeating units are suitable. Urethanes are typically prepared by the condensation of a diisocyanate with a diol. Aliphatic urethanes having at least two urethane moieties per repeating unit are useful. In addition, the diisocyanate and diol used to prepare the urethane comprise divalent aliphatic groups that may be the same or different.

In one embodiment, the oligomer containing at least one ethylenically unsaturated functional group comprises polyester urethane-based oligomer or polyether urethane-based oligomer containing at least one ethylenically unsaturated functional group. The ethylenically unsaturated functional group can be those containing carbon-carbon unsaturated double bond, such as acrylate groups, methacrylate groups, vinyl groups, allyl groups, acrylamide groups, methacrylamide groups etc., preferably acrylate groups and methacrylate groups.

Suitable urethane-based oligomers are known in the art and may be readily synthesized by a number of different procedures. For example, a polyfunctional alcohol may be reacted with a polyisocyanate (preferably, a stoichiometric excess of polyisocyanate) to form an N CO-terminated pre-oligomer, which is thereafter reacted with a hydroxy-functional ethylenically unsaturated monomer, such as hydroxyfunctional (meth)acrylate. The polyfunctional alcohol may be any compound containing two or more OH groups per molecule and may be a monomeric polyol (e.g., a glycol), a polyester polyol, a polyether polyol or the like. The urethane-based oligomer in one embodiment of the invention is an aliphatic urethane-based oligomer containing (meth)acrylate functional group.

Suitable polyether or polyester urethane-based oligomers include the reaction product of an aliphatic or aromatic polyether or polyester polyol with an aliphatic or aromatic polyisocyanate that is functionalized with a monomer containing the ethylenically unsaturated functional group, such as (meth)acrylate group. In a preferred embodiment, the polyether and polyester are aliphatic polyether and polyester, respectively. In a preferred embodiment, the polyether and polyester urethane-based oligomers are aliphatic polyether and polyester urethane-based oligomers and comprise (meth)acrylate group.

In one embodiment, the viscosity of the oligomer containing at least one ethylenically unsaturated functional group can be in the range from 200 to 200000 cps, for example 500 cps, 800 cps, 1000 cps, 2000 cps, 3000 cps, 4000 cps, 5000 cps, 6000 cps, 7000 cps, 8000 cps, 10000 cps, 20000 cps, 30000 cps, 40000 cps, 50000 cps, 60000 cps, 70000 cps, 80000 cps, 90000 cps, 95000 cps, preferably 500 to 60000cps, for example 1000 to 50000 cps, 2000 to 40000 cps, 3000 to 20000 cps, 4000 to 15000 cps, or 20000 cps to 60000 cps, as measured according to DIN EN ISO 3219 at 23 °C.

In one embodiment, the viscosity of the oligomer containing at least one ethylenically unsaturated functional group can be in the range from 10 to 100 cps, for example 12, 15, 18, 20, 30, 50, 60, 80 or 90 cps at 23°C (shear rate D 100s^-1).

The monomer can lower the viscosity of the composition. The monomer can be monofunctional or multifunctional (such as difunctional, trifunctional). In one embodiment, the monomer can be selected from the group consisting of (meth)acrylate monomers, (meth)acrylamide monomers, vinylaromatics having up to 20 carbon atoms, vinyl esters of carboxylic acids having up to 20 carbon atoms, a,p- unsaturated carboxylic acids having 3 to 8 carbon atoms and their anhydrides, and vinyl substituted heterocycles, In the context of the present disclosure, the term “(meth)acrylate monomer” means a monomer comprises a (meth)acrylate moiety. The structure of the (meth)acrylate moiety is as follows:

wherein R is H or methyl.

The (meth)acrylate monomer can be monofunctional or multifunctional (such as difunctional, trifunctional) (meth)acrylate monomer. Exemplary (meth)acrylate monomer can include Ci to C20 alkyl (meth)acrylate, Ci to C10 hydroxyalkyl (meth)acrylate, C3 to C10 cycloalkyl (meth)acrylate, urethane acrylate, 2-(2- ethoxy)ethyl acrylate, tetrahydrofurfuryl (meth)acrylate, 2-phenoxyethylacrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentadienyl (meth)acrylate, caprolactone (meth)acrylate, morpholine (meth)acrylate, ethoxylated nonyl phenol (meth)acrylate, (5-ethyl-1,3-dioxan-5-yl) methyl acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, phenethyl (meth)acrylate, dicyclopentanyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate and dicyclopentenyl (meth)acrylate.

Specific examples of Ci to C20 alkyl (meth)acrylate can include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, sec-butyl (meth)acrylate, pentyl (meth)acrylate, n-hexyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, n-lauryl (meth)acrylate, n-tridecyl (meth)acrylate, n-cetyl (meth)acrylate, n-stearyl (meth)acrylate, isomyristyl (meth)acrylate, stearyl (meth)acrylate, and isostearyl (meth)acrylate (ISTA). C₆ to Cis alkyl (meth)acrylate, especially C₆ to C16 alkyl (meth)acrylate or Cs to C12 alkyl (meth)acrylate is preferred.

Specific examples of Ci to C10 hydroxyalkyl (meth)acrylate, such as C2 to Cs hydroxyalkyl (meth)acrylate can include 2-hydroxyethyl (meth)acrylate, 2- hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4- hydroxy butyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, or 3- hydroxy-2-ethylhexyl (meth)acrylate etc. Specific examples of C3 to C10 cycloalkyl (meth)acrylate can include isobornyl acrylate, isobornyl methacrylate, cyclohexyl acrylate or cyclohexyl methacrylate.

Examples of the multifunctional (meth)acrylate monomer can include (meth)acrylic esters and especially acrylic esters of polyfunctional alcohols, particularly those which other than the hydroxyl groups comprise no further functional groups or, if they comprise any at all, comprise ether groups. Examples of such alcohols are, e.g., difunctional alcohols, such as ethylene glycol, propylene glycol, and their counterparts with higher degrees of condensation, for example such as diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol etc., 1 ,2-, 1 ,3- or 1 ,4-butanediol, 1 ,5-pentanediol, 1 ,6-hexanediol, 3-methyl-1 ,5-pentanediol, neopentyl glycol, alkox- ylated phenolic compounds, such as ethoxylated and/or propoxylated bisphenols, 1 ,2-, 1 ,3- or 1 ,4-cyclohexanedimethanol, alcohols with a functionality of three or higher, such as glycerol, trimethylolpropane, butanetriol, trimethylolethane, pentaerythritol, ditrimethylolpropane, dipentaerythritol, sorbitol, mannitol, and the corresponding alkoxylated, especially ethoxylated and/or propoxylated, alcohols.

Specific example of the multifunctional (meth)acrylate monomer can include 1 ,4-bu- tanediol di(meth)acrylate, 1 ,6-hexanediol di(meth)acrylate, dipropyleneglycol di(meth)acrylate pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and mixtures thereof.

In the context of the present disclosure, specific example of (meth)acrylamide monomer can include acryloylmorpholine, methacryloylmorpholine, N- (hydroxymethyl)acrylamide, N-hydroxyethyl acrylamide, N-isopropylacrylamide, N- isopropylmethacrylamide, N-tert-butylacrylamide, N,N’-methylenebisacrylamide, N- (isobutoxymethyl)acrylamide, N-(butoxymethyl)acrylamide, N-[3- (dimethylamino)propyl]methacrylamide, N,N-dimethylacrylamide, N,N- diethylacrylamide, N-(hydroxymethyl)methacrylamide, N-hydroxyethyl methacrylamide, N- isopropylmethacrylamide, N-isopropylmethacrylamide, N-tert- butylmethacrylamide, N,N’-methylenebismethacrylamide, N- (isobutoxymethyl)methacrylamide, N-(butoxymethyl)methacrylamide, N-[3- (dimethylamino)propyl]methacrylamide, N,N-dimethylmethacrylamide and N,N- diethylmethacrylamide. The (meth)acrylamide monomer can be used alone or in combination. Examples of vinylaromatics having up to 20 carbon atoms can include, such as styrene and Ci-C4-alkyl substituted styrene, such as vinyltoluene, p-tert-butylstyrene and a-methyl styrene.

Examples of vinyl esters of carboxylic acids having up to 20 carbon atoms (for example 2 to 20 or 8 to 18 carbon atoms) can include vinyl laurate, vinyl stearate, vinyl propionate, and vinyl acetate.

Example of a,p-unsaturated carboxylic acids having 3 to 8 carbon atoms can be acrylic acid or methacrylic acid.

Examples of vinyl substituted heterocycles can include monovinyl substituted heterocycles, wherein the heterocycle is a 5- to 8-membered ring containing 2 to 7 carbon atoms, and 1 to 4 (preferably 1 or 2) heteroatoms selected from N, O and S, for example pyridine, pyrrolidone, morpholine, morpholinone, caprolactam, imidazole and oxazolidinone. Specific examples of vinyl substituted heterocycles can include vinylpyridines, N-vinylpyrrolidone, N-vinylmorpholin-2-one, N-vinyl caprolactam and 1-vinylimidazole, vinyl alkyl oxazolidinone such as vinyl methyl oxazolidinone, and 4- acryloylmorpholine.

Preferred monomers are (meth)acrylate monomer, especially multifunctional (meth)acrylate monomer, C3 to C10 cycloalkyl (meth)acrylate, vinylaromatics having up to 20 carbon atoms, and vinyl substituted heterocycles, and mixture thereof, for example a mixture of multifunctional (meth)acrylate monomer and one or more of C3 to C10 cycloalkyl (meth)acrylate, vinylaromatics having up to 20 carbon atoms, and vinyl substituted heterocycles.

In a preferred embodiment, reactive component (2) of the present invention comprises the oligomer containing at least one ethylenically unsaturated functional group.

In a preferred embodiment, reactive component (2) of the present invention comprises both the oligomer and the monomer containing at least one ethylenically unsaturated functional group. The weight ratio of the oligomer to the monomer can be in the range from 10:1 to 1 :10 (for example 9:1 , 8:1 , 7:1 , 6:1 , 5:1 , 4:1 , 3:1 , 2:1 , 1 :1 , 1 :2, 1 :3, 1 :4, 1 :5, 1 :6, 1 :7, 1 :8, 1 :9), preferably from 8: 1 to 1 :8, or from 5: 1 to 1 :5, or from 4:1 to 1 :4. In an embodiment, reactive component (2) of the present invention only comprises the oligomer containing at least one ethylenically unsaturated functional group, i.e. , does not comprise the monomer containing at least one ethylenically unsaturated functional group.

The amount of reactive component (2) can be in the range from 10 to 99.8 wt.%, for example 15wt.%, 20 wt.%, 25 wt.%, 30 wt.%, 35 wt.%, 40 wt.%, 45 wt.%, 50 wt.%, 55 wt.%, 60 wt.%, 70 wt.%, 80 wt.%, 85 wt.%, 90 wt.%, 92 wt.%, 95 wt.%, 96 wt.%, 98 wt.%, 99 wt.%, 99.5 wt.%, preferably in the range from 20 to 99 wt.%, or from 30 to 98 wt.%, or from 40 to 97 wt.%, or from 50 to 96 wt.%, or from 60 to 95 wt.%, or from 70 to 95 wt.%, based on the total weight of the radiation curable liquid composition of the present invention.

Component (3): Photo-initiator

The curable composition of the present invention comprises at least one photoinitiator as component (3). For example, photo-initiator component (3) may include at least one free radical photo-initiator and/or at least one ionic photo-initiator (for example cationic photo-initiator), and preferably at least one (for example one or two) free radical photo-initiator. It is possible to use all photo-initiators known in the art for use in compositions for 3D-printing, e.g., it is possible to use photo-initiators that are known in the art suitable for SLA, DLP or PPJ processes.

As examples of the photo-initiator for the present invention, it is possible to use those referred to in "Advances in Polymer Science", Volume 14, Springer Berlin 1974 or in K. K. Dietliker, Chemistry and Technology of UV and EB Formulation for Coatings, Inks and Paints, Volume 3; Photo-initiators for Free Radical and Cationic Polymerization, P. K. T. Oldring (Ed.), SITA Technology Ltd, London.

Suitable examples include phosphine oxides, benzophenones, a-hydroxyalkyl aryl ketones, thioxanthones, anthraquinones, acetophenones, benzoins and benzoin ethers, ketals, imidazoles or phenylglyoxylic acids, and mixtures thereof.

Phosphine oxides are for example monoacyl- or bisacylphosphine oxides, such as lrgacure®819 (bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide), as described for example in EP-A 7 508, EP-A 57474, DE-A 196 18 720, EP-A 495 751 or EP-A 615 980, such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Lucirin® TPO), ethyl 2,4,6-trimethylbenzoylphenylphosphinate or bis(2,6-dimethoxybenzoyl)-2,4,4- trimethylpentylphosphine oxide. Benzophenones are for example benzophenone, 4-aminobenzophenone, 4,4'- bis(dimethylamino)benzophenone, 4-phenylbenzophenone, 4-chlorobenzophenone, Michler's ketone, o-methoxybenzophenone, 2,4,6-trimethylbenzophenone, 4- methylbenzophenone, 2,4-dimethylbenzophenone, 4-isopropylbenzophenone, 2- chlorobenzophenone, 2,2'-dichlorobenzophenone, 4-methoxybenzophenone, 4- propoxybenzophenone or 4-butoxybenzophenone. a-hydroxyalkyl aryl ketones are for example 1-benzoylcyclohexan-1-ol (1- hydroxycyclohexyl phenyl ketone), 2-hydroxy-2,2-dimethylacetophenone (2-hydroxy- 2-methyl-1-phenylpropan-1-one), 1 -hydroxyacetophenone, 1-[4-(2- hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1 -propan- 1 -one or polymer containing 2- hydroxy-2-methyl-1-(4-isopropen-2-ylphenyl)propan-1-one in copolymerized form (Esacure® KIP 150).

Xanthones and thioxanthones are for example 10-thioxanthenone, thioxanthen-9- one, xanthen-9-one, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4- diisopropylthioxanthone, 2,4-dichlorothioxanthone or chloroxanthenone.

Anthraquinones are for example p-methylanthraquinone, tert-butylanthraquinone, anthraquinonecarboxylic esters, benz[de]anthracen-7-one, benz[a]anthracen-7, 12- dione, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1- chloroanthraquinone or 2-amylanthraquinone.

Acetophenones are for example acetophenone, acetonaphthoquinone, valerophenone, hexanophenone, a-phenylbutyrophenone, p- morpholinopropiophenone, dibenzosuberone, 4-morpholinobenzophenone, p- diacetylbenzene, 4'-methoxyacetophenone, a-tetralone, 9-acetylphenanthrene, 2- acetylphenanthrene, 3-acetylphenanthrene, 3-acetylindole, 9-fluorenone, 1 -indanone, 1 ,3,4-triacetylbenzene, 1 -acetonaphthone, 2-acetonaphthone, 2,2-dimethoxy-2- phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 1 ,1- dichloroacetophenone, 1 -hydroxyacetophenone, 2,2-diethoxyacetophenone, 2- methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2,2-dimethoxy-1 ,2- diphenylethan-2-one or 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butan-1- one.

Benzoins and benzoin ethers are for example 4-morpholinodeoxybenzoin, benzoin, benzoin isobutyl ether, benzoin tetrahydropyranyl ether, benzoin methyl ether, benzoin ethyl ether, benzoin butyl ether, benzoin isopropyl ether or 7H-benzoin methyl ether.

Ketals are for example acetophenone dimethyl ketal, 2,2-diethoxyacetophenone, or benzil ketals, such as benzil dimethyl ketal.

Phenylglyoxylic acids are described for example in DE-A 19826 712, DE-A 199 13 353 or WO 98/33761.

Photo-initiators which can be used as well are for example benzaldehyde, methyl ethyl ketone, 1 -naphthaldehyde, triphenylphosphine, tri-o-tolylphosphine or 2,3- butaned-ione.

Appropriate mixtures of photo-initiators may also be used. Typical mixtures include for example:

2-hydroxy-2-methyl-1-phenylpropan-2-one and 1 -hydroxycyclohexyl phenyl ketone; bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide and 2-hydroxy-2- methyl-1-phenylpropan-1-one; benzophenone and 1 -hydroxycyclohexyl phenyl ketone; bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide and 1- hydroxycyclohexyl phenyl ketone;

2.4.6-trimethylbenzoyldiphenylphosphine oxide and 2-hydroxy-2-methyl-1- phenylpropan-1-one;

2.4.6-trimethylbenzophenone and 4-methylbenzophenone; or

2.4.6-trimethylbenzophenone, and 4-methylbenzophenone and 2,4,6- trimethylbenzoyldiphenylphosphine oxide.

The amount of the photo-initiator (3) can be in the range from 0.1 to 10 wt.%, for example 0.2 wt.%, 0.5 wt.%, 0.8 wt.%, 1 wt.%, 2 wt.%, 3 wt.%, 5 wt.%, 8 wt.%, or 10 wt.%, preferably in the range from 0.1 to 8 wt.% or from 0.1 to 5 wt.% or from 0.5 to 5 wt.%, based on the total weight of the radiation curable liquid composition of the present invention.

The radiation curable liquid composition of the present invention has a low viscosity even without the addition of the solvent. In an embodiment, the viscosity of the radiation curable liquid composition is no more than 2000 cps (for example 1950 cps, or 1900 cps, or 1800 cps, or 1500 cps, or 1200 cps, or 1000 cps, or 800 cps, or 600 cps, or 500 cps, or 400 cps, or 300 cps, or 250 cps, or 200 cps, or 150 cps), or no more than 1950 cps, or no more than 1900 cps, or no more than 1800 cps, or no more than 1500 cps, or in the range from 150 to 2000 cps, or in the range from 200 to 2000 cps, or in the range from 300 to 1950 cps. The viscosity is measured according to DIN EN ISO 3219 at 23°C.

In one embodiment, the radiation curable liquid composition of the present invention, comprising following components:

(1) 0.1 to 50 wt.% of at least one radiation curable hyperbranched polymer containing polyimide moiety;

(2) 10 to 99.8 wt.% of at least one reactive component; and

(3) 0.1 to 10 wt.% of at least one photo-initiator; in each case based on the total weight of the radiation curable liquid composition.

(1) 1 to 40 wt.% of at least one radiation curable hyperbranched polymer containing polyimide moiety;

(2) 20 to 99 wt.% of at least one reactive component; and

(3) 0.1 to 8 wt.% of at least one photo-initiator; in each case based on the total weight of the radiation curable liquid composition.

(1) 2 to 35 wt.% of at least one radiation curable hyperbranched polymer containing polyimide moiety;

(2) 30 to 98 wt.% of at least one reactive component; and

(1) 3 to 35 wt.% of at least one radiation curable hyperbranched polymer containing polyimide moiety;

(2) 40 to 97 wt.% of at least one reactive component; and

(3) 0.1 to 8 wt.% of at least one photo-initiator; in each case based on the total weight of the radiation curable liquid composition. In one embodiment, the radiation curable liquid composition of the present invention, comprising following components:

(1) 4 to 35 wt.% of at least one radiation curable hyperbranched polymer containing polyimide moiety;

(2) 50 to 96 wt.% of at least one reactive component; and

(2) 60 to 95 wt.% of at least one reactive component; and

(1) 5 to 35 wt.% of at least one radiation curable hyperbranched polymer containing polyimide moiety;

(2) 60 to 94 wt.% of at least one reactive component; and

(2) 60 to 95 wt.% of at least one reactive component; and

(3) 0.1 to 5 wt.% of at least one photo-initiator; in each case based on the total weight of the radiation curable liquid composition.

(1) 5 to 30 wt.% of at least one radiation curable hyperbranched polymer containing polyimide moiety;

(2) 65 to 94 wt.% of at least one reactive component; and

(3) 0.5 to 5 wt.% of at least one photo-initiator; in each case based on the total weight of the radiation curable liquid composition.

Component (4)-auxiliary agents

For practical applications, optionally, the curable composition of the present invention may further comprise auxiliary agents as component (4).

As auxiliary agents, mention may be made by way of preferred example of surfactants, diluents, flame retardants, nucleating agents, lubricant, dyes, pigments, catalyst, UV absorbers and stabilizers, e.g., against oxidation, hydrolysis, light, heat or discoloration, inorganic and/or organic fillers, reinforcing materials and plasticizers. As hydrolysis inhibitors, preference is given to oligomeric and/or polymeric aliphatic or aromatic carbodiimides. To stabilize the cured material of the invention against aging and damaging environmental influences, stabilizers are added to system in preferred embodiments.

Surfactants are surface active compounds, such as anionic, cationic, nonionic and amphoteric surfactants, and mixtures thereof. Such surfactants can be used for example as dispersant, solubilizer, and the like. Examples of surfactants are listed in McCutcheon's, Vol. 1 : Emulsifiers & Detergents, McCutcheon's Directories, Glen Rock, USA, 2008 (International Ed. or North American Ed.). Suitable anionic surfactants may be alkali, alkaline earth or ammonium salts of sulfonates, sulfates, phosphates, carboxylates, and mixtures thereof. Suitable nonionic surfactants may be alkoxylates, N-substituted fatty acid amides, amine oxides, esters, sugar-based surfactants, polymeric surfactants, and mixtures thereof. Suitable cationic surfactants may be quaternary surfactants, for example quaternary ammonium compounds with one or two hydrophobic groups, or salts of long chain primary amines. Suitable amphoteric surfactants may be alkylbetains and imidazolines.

If the composition of the invention is exposed to thermo-oxidative damage during use, in preferred embodiments, antioxidants are added. Preference is given to phenolic antioxidants. Phenolic antioxidants such as Irganox® 1010 from BASF SE are given in Plastics Additive Handbook, 5th edition, H. Zweifel, ed., Hanser Publishers, Munich, 2001 , pages 98-107, page 116 and page 121.

If the composition of the invention is exposed to UV light, it is preferably additionally stabilized with a UV absorber. UV absorbers are generally known as molecules which absorb high-energy UV light and dissipate energy. Customary UV absorbers which are employed in industry belong, for example, to the group of cinnamic esters, diphenylcyan acrylates, formamidines, benzylidenemalonates, diarylbutadienes, triazines and benzotriazoles. Examples of commercial UV absorbers may be found in Plastics Additive Handbook, 5th edition, H. Zweifel, ed, Hanser Publishers, Munich, 2001 , pages 116-122.

Further details regarding the abovementioned auxiliary agents may be found in the specialist literature, e.g., in Plastics Additive Handbook, 5th edition, H. Zweifel, ed, Hanser Publishers, Munich, 2001.

Plasticizers can be used to lower the glass transition temperature (Tg) of the polymer. Plasticizers work by being embedded between the chains of polymers, spacing them apart (increasing the “free volume”), and thus lowering the glass transition temperature of the polymer and making it softer. Plasticizers may be selected by a skilled person for the present invention according to practical applications. Exemplary plasticizers include polycarboxylic acids and their esters, epoxidized vegetable oils; sulfonamides, organophosphates, glycols/polyether and their derivatives, polymeric plasticizer, biodegradable plasticizers, and the like. For example, the plasticizers can be selected from the group consisting of cyclohexane dicarboxylic acid and its esters, preferably esters of 1 ,2-cyclohexane dicarboxylic acid, more preferably 1 ,2-cyclohex- ane dicarboxylic acid diisononyl ester (such as Hexamoll® DINCH from BASF SE).

When present, the amount of component (4) in the curable composition of the present invention may be in the range from 0 to 60% by weight, for example 5% by weight, 10% by weight, 15% by weight, 20% by weight, 25% by weight, 30% by weight, 35% by weight, 40% by weight, 50% by weight, 60% by weight, preferably from 0 to 50% by weight, or from 0 to 40% by weight, or from 0 to 30% by weight, based on the total weight of the radiation curable liquid composition of the present invention.

The radiation curable liquid composition of the present invention can be prepared by mixing the components of the composition.

According to an embodiment of the invention, the mixing can be carried out at room temperature with stirring. There is no particular restriction on the time of mixing and rate of stirring, as long as all components are uniformly mixed together. In a specific embodiment, the mixing can be carried out at 1000 to 3000 RPM, preferably 1500 to 2500 RPM for 5 to 60 min, more preferably 6 to 30 min. 3D-printed object and preparation thereof

One aspect of the present invention relates to a process of forming 3D-printed object, comprising using the radiation curable liquid composition of the present invention.

In one embodiment of the present invention, the process comprises the steps of: (p-i) forming a layer of the radiation curable liquid composition;

(p-v) repeating steps (p-iii) and (p-iv) until the 3D object is manufactured.

According to the invention, the curing time in step (p-ii) or (p-iv) is from 0.5 to 15s, such as from 1 to 10 s or 1 to 6s. There is no specific restriction on temperature during curing. Specifically, the temperature during curing depends on material and 3D printer used.

In one embodiment, the process further comprises a step of post-curing the 3D object obtained in step (p-v) as a whole to form a final 3D object. The post-curing can be carried out by UV radiation, thermal treatment or combination thereof.

Usually, the temperature in the thermal treatment is in the range from 90 to 160 °C, preferably 100 to 140 °C. According to the invention, the post-curing time can be in the range from 30 min to 500 min, for example 60 min, 120 min, 180 min, 250 min, 300 min, 400 min, preferably from 60 min to 250 min.

Radiation used in steps (p-ii) or (p-iv) may be adopted by a skilled person according to the practical 3D-printing applications. For example, the radiation may be actinic ray that has sufficient energy to initiate a polymerization or cross-linking reaction. The actinic ray can include but is not limited to a-rays, y-rays, ultraviolet radiation (UV radiation), visible light, and electron beams, wherein UV radiation and electron beams, especially, UV radiation is preferred. In a specific embodiment, the wavelength of the radiation light can be in the range from 350 to 480 nm, for example 365 nm, 385 nm, 395 nm, 405 nm, 420 nm , 440nm, 460nm, 480nm.

Stereolithography (SLA), digital light processing (DLP), photopolymer jetting (PPJ), LCD technology or other techniques known by a person skilled in the art can be employed in of the process of forming 3D-printed objects of the present invention. Preferably, the production of cured 3D objects of complex shape is performed for instance by means of stereolithography.

The present invention further relates to a 3D-printed object formed from the radiation curable liquid composition of the present invention or obtained by the process of the present invention.

Non-limiting examples of the 3D-printed objects comprise sole, outerwear, cloth, footwear, toy, mat, tire, hose, gloves, seals, medical appliances such as hearing aids, dental parts.

A further aspect of this disclosure relates to use of the radiation curable liquid composition of the present invention in 3D-printing. The specific techniques are as mentioned above.

Examples

The present invention will be better understood in view of the following non-limiting examples.

Materials and abbreviation

6FDA: 4,4'-hexafluoroisopropylidene diphthalic anhydride (6FDA)

ODPA: 4,4'-oxydiphthalic anhydride

TrMPD : 2,4,6-Trimethyl-1 ,3-phenylenediamine

TMAN: Trimellitic anhydride

MA: Maleic anhydride

DCC: N,N'-Dicyclohexylcarbodiimide

EDC-HCI: (3-dimethylaminopropyl)-ethylcarbodiimide-hydrochloride

DMAP: 4-(Dimethylamino)pyridine

DMAc: N,N-Dimethylacetamide

NMP: N-Methyl-2-pyrrolidinone DCM: Dichloromethane

THF: Tetra hydrofuran

DMF: N,N-Dimethylformamide

DMSO: Dimethyl sulfoxide

DPGDA: dipropyleneglycol diacrylate

I BOA: Isobornyl acrylate

Vmox: vinyl methyl oxazolidinone

ACMO: 4-acryloylmorpholine

Ultracur3D® ST 45 from BASF: radiation curable composition of reactive urethane photopolymers based on acrylate resin and suitable for 3D printing.

BR-541MB: Polyether urethane methacrylates having a viscosity of 6,800 cps at 60

°C and a Tg (DMA) of 74 °C, Dymax;

LAROMER UA 9089: an aliphatic urethane di-acrylate resin, viscosity at 23°C (shear rate D 100s’¹): 18-24 cps, BASF

TPO: 2,4,6-trimethylbenzoyldiphenylphosphine oxide

Methods

(1) 1 H NMR spectra was obtained in DMSO-d6 using a Bruker HD400 MHz equipment.

(2) Solubility: The radiation curable hyperbranched polyimide sample was added to an organic solvent at a concentration of 5 w/v% and stirred at room temperature. If the sample was completely dissolved and a homogeneous and clear solution was obtained, it was considered that the sample was well soluble in the solvent.

(3) Miscibility: The radiation curable hyperbranched polyimide and a reactive diluent were added to a 3-neck flack. The mixture was mechanically stirred at room temperature till the solid was completely dissolved. Good miscibility, here, means the minimal content of the photo-curable hyperbranched polyimide in the mixture is above 10 w%.

(4) Tensile test (including Tensile strength, Elongation at break and Young’s modulus):

Tensile strength and Elongation at break were determined according to ISO 527- 5:2009 with Zwick, Z050 Tensile equipment, wherein the parameters used include: Start position: 50 mm; Pre-load: 0.02 MPa; Test speed: 50 mm/min.

(5) Viscosity: DIN EN ISO 3219 at 23°C.

(6) Tg: Tg was measured by DSC by ramping at 10 °C/min from room temperature to 200 °C under nitrogen flow in the chamber.

(7): Heat deflection temperature (HDT)

Heat deflection temperature was determined in accordance with ASTM D648-07. Example 1 : Chemical synthesis, solubility investigation

1. Synthesis of a triamine monomer 1 ,3,5-tris(4-amino-3-methylphenoxy)benzene (TAMPB)

The synthesis involves two-step reactions as illustrated below.

1) Preparing TNMPB

A mixture of 7.56 g (60 mmol) of 1 ,3,5-Trihydroxybenzene, 27.1 g (180 mmol) of 4- fluoro-2-methyl-1-nitroenzene, 21.0 g (360 mmol) of potassium fluoride and 180 mL of dimethyl sulfoxide was heated at 200 °C for 0.5 h. The reaction mixture was allowed to cool to room temperature and poured into 700 mL of water. The solid was filtered, washed with 100 mL of water, and dried in air. The crude solid was recrystallized from ethyl acetate to yield 26.5 g (83%, yield) of an off-white solid product.

2) Preparing TAMPB

1 ,3,5-Tris(4-nitro-3-methylphenoxy)benzene (TNMPB) (10.0 mmol, 5.31 g), 340 mg Pd/C and 250 mL of methanol were added to a 500 mL three-necked flask equipped with a condenser, mechanical stirrer and addition funnel. The reaction mixture was heated in a thermocouple-regulated oil bath set at 70 °C and continuously stirred. A mixture of hydrazine hydrate (17.64 g, 300 mmol) and methanol (40 mL) was added dropwise through an addition funnel. After complete addition, a temperature of 70 °C was maintained for additional 20 h. The reaction mixture was cooled to room temperature and then filtered. The filtrate was poured into water. The solid was collected by filtration, washed with water and dried in vacuo at 60 °C overnight to yield 4.23 g (96%, yield) of a white solid product.

2. Synthesis of a radiation curable hyperbranched polyimide (PI-1) i) synthesis of an amine-terminated hyperbranched polyamic acid A 4.5 mmol aliquot of TAMPB was dissolved in 45 mL of DMAc in a 250 mL thoroughly dried three-neck flask under N2 flow. The contents were stirred with a magnetic stirring bar at room temperature, and 4.365 mmol of ODPA in 45 mL of DMAc was added dropwise through a syringe over 10 h. After the addition was finished, the reaction mixture was further stirred at room temperature for 3 h. The resulting hyperbranched polyamic acid homogenous solution was directly used for next step reaction. ii) synthesis of trimellitic anhydride-modified hyperbranched polyamic acid

6.4 mmol of trimellitic anhydride (TMAN) was added to the solution obtained in step (i) in one portion and the reaction mixture was stirred at room temperature for additional 2 h. iii) chemical imidization (carboxyl-terminated hyperbranched polyimide)

A mixture of 5.4 g of trimethylamine (catalyst) and 5.4 g of acetic anhydride was added dropwise to the solution mixture of step (ii), and the reaction mixture was stirred at room temperature and 60 °C for 3 h and 5 h, respectively. After cooling to room temperature, the mixture was poured into water and the precipitate was dried in vacuo. The dry solid was re-dissolved in 25 mL of DMAc and added dropwise into 100 mL (18 mmol HCI) dilute hydrochloric acid solution. The precipitate was collected by filtration and dried in vacuo at 60 °C to yield 4.0 g (91 %, yield) white solid product. iv) synthesis of a radiation curable hyperbranched polyimide

0.3570 g (0.42 mmol carboxyl groups) of the carboxyl-terminated hyperbranched polyimide (product of step (iii)), 0.1951 g (1.68 mmol) of 2-hydroxyethyl acrylate (HEA), 10 mg (0.08 mmol) of DMAP and 0.8 mL of NMP were added to a completely dried 3- neck flask. The reaction mixture was magnetically stirred at room temperature under nitrogen atmosphere till a clear solution was obtained. A DCC (0.2600 g, 1.26 mmol) solution in NMP (0.4 mL) was added dropwise to the reaction flask. The reaction mixture was stirred at room temperature for 24 h to carry out Steglich esterification. Afterwards, the mixture was filtered and the filtrate was precipitated from diethyl ether. The precipitate was re-dissolved in DCM and precipitated again in diethyl ether. The dissolution-precipitation was repeated three times to remove any impurities. The finally formed precipitate was dried in vacuo at 30 °C to yield 0.30 g (77%, yield) white solid product (radiation curable hyperbanched polyimide) named as PI-1.

3. Characterizations 1) 1 H NMR spectrum of the radiation curable hyperbranched polyimide PI-1 synthesized in example 1 in DMSO-d6 was shown in Figure 2. The peak assignments were also shown in Figure 2. The peaks around 4.6 ppm were assigned to the four methylene protons (-OCH2CH2O-) of the HEA unit indicating successful grafting of HEA.

2) Solubility

The radiation curable hyperbranched polyimide PI-1 was well soluble in DCM, THF, DMAc, NMP, DMF and DMSO.

3) Miscibility

The radiation curable hyperbranched polyimide PI-1 showed good miscibility with vinyl methyl oxazolidinone (Vmox) and 4-acryloylmorpholine (ACMO).

Example 2:

1. Synthesis of a radiation curable hyperbranched polyimide (PI-2) i) synthesis of an amine-terminated hyperbranched polyamic acid

A 15 mmol aliquot of TAMPB was dissolved in 150 mL of DMAc in a 500 mL thoroughly dried three-neck flask under N₂ flow. The contents were stirred with a magnetic stirring bar at room temperature, and 10.5 mmol of 6FDA in 95 mL of DMAc was added dropwise through a syringe over 4 h. After the addition was finished, the reaction mixture was further stirred at room temperature for 10 h. The resulting hyperbranched polyamic acid homogenous solution was directly used for next step reaction. ii) synthesis of trimellitic anhydride-modified hyperbranched polyamic acid

28.8 mmol of trimellitic anhydride (TMAN) was added in one portion to the solution obtained in step i) and the reaction mixture was stirred at room temperature for additional 10 h. iii) chemical imidization

A mixture of 18.0 g of trimethylamine (catalyst) and 18.0 g of acetic anhydride was added dropwise to the solution mixture obtained in step (ii), and the reaction mixture was stirred at room temperature and 60 °C for 3 h and 5 h, respectively. After cooling to room temperature, the mixture was poured into 1.2 L (216 mmol HCI) dilute hydrochloric acid solution and the precipitate was dried in vacuo. The dry solid was re-dis- solved in 40mL of DMAc and added dropwise into 400 mL (24 mmol HCI) dilute hydrochloric acid solution. The precipitate was collected by filtration and dried in vacuo at 60 °C to yield 13.6 g (91%, yield) white solid product. iv) synthesis of a radiation curable hyperbranched polyimide

8.50 g (13.52 mmol carboxyl groups) of the carboxyl-terminated hyperbranched polyimide (product of step (iii)), 1.88 g (16.2 mmol) of 2-hydroxyethyl acrylate (HEA), 165 mg (1.35 mmol) of DMAP and 45 g of DCM were added to a completely dried 3-neck flask. The reaction mixture was magnetically stirred at 0 °C under nitrogen atmosphere. EDC-HCI (3.89 g, 27.04 mmol) was added to the reaction flask in three batches. The reaction mixture was stirred at room temperature for 24 h to carry out Steglich esterification. Afterwards, the mixture was distilled at 30 °C under reduced pressure to remove the solvent and dissolved in 65 g THF. The mixture was filtered and the filtrate was precipitated from H₂O. The dissolution-precipitation was repeated three times to remove any impurities. The finally formed precipitate was dried in vacuo at 30 °C to yield 7.7 g (77%, yield) white solid product named as PI-2.

2. Characterizations

1) 1 H NMR spectrum of the radiation curable hyperbranched polyimide PI-2 in DMSO-d6 was shown in Figure 3. The peak assignments were also shown in Figure

3. The peaks around 4.6 ppm were assigned to the four methylene protons (- OCH2CH2O-) of the HEA unit indicating successful grafting of HEA.

2) Solubility

The radiation curable hyperbranched polyimide PI-2 was well soluble in DCM, THF, DMAc, NMP, DMF and DMSO.

3) Miscibility

The radiation curable hyperbranched polyimide PI-2 showed good miscibility with vinyl methyl oxazolidinone (Vmox), 4-acryloylmorpholine (ACMO) and Ultracur3D® ST 45.

Example 3:

1. Synthesis of a radiation curable hyperbranched polyimide (PI-3) i) synthesis of an amine-terminated hyperbranched polyamic acid A 4.5 mmol aliquot of TAMPB was dissolved in 42 mL of DMAc in a 250 mL thoroughly dried three-neck flask under N₂ flow. The contents were stirred with a magnetic stirring bar at room temperature, and 3.83 mmol of 6FDA in 36 mL of DMAc was added dropwise through a syringe over 2 h. After the addition was finished, the reaction mixture was further stirred at room temperature for 10 h. The resulting hyperbranched polyamic acid homogenous solution was directly used for next step reaction. ii) synthesis of trimellitic anhydride-modified hyperbranched polyamic acid

7.02 mmol of trimellitic anhydride (TMAN) was added in one portion to the solution obtained in step (i) and the reaction mixture was stirred at room temperature for additional 10 h. iii) chemical imidization

A mixture of 5.4 g of trimethylamine (catalyst) and 5.4 g of acetic anhydride was added dropwise to the solution mixture obtained in step (ii), and the reaction mixture was stirred at room temperature and 60 °C for 3 h and 5 h, respectively. After cooling to room temperature, the mixture was poured into 700mL (54 mmol HCI) dilute hydrochloric acid solution and the precipitate was dried in vacuo. The dry solid was re-dis- solved in 20 mL of DMAc and added dropwise into 100 mL (7 mmol HCI) dilute hydrochloric acid solution. The precipitate was collected by filtration and dried in vacuo at 60 °C to yield 4.3 g (91 %, yield) white solid product. iv) synthesis of a radiation curable hyperbranched polyimide

4.31 g (5.95 mmol carboxyl groups) of the carboxyl-terminated hyperbranched polyimide (product of step (iii)), 0.35 g (2.98 mmol) of 2-hydroxyethyl acrylate (HEA), 75.3 mg (0.59 mmol) of DMAP and 11mL of NMP were added to a completely dried 3- neck flask. The reaction mixture was magnetically stirred at 0 °C under nitrogen atmosphere. DCC (2.45 g, 11.9 mmol) was added to the reaction flask in three batches. The reaction mixture was stirred at room temperature for 24 h to carry out Steglich esterification. Afterwards, the mixture was filtered and the filtrate was precipitated from Et20. The dissolution-precipitation was repeated three times to remove any impurities. The finally formed precipitate was dried in vacuo at 30 °C to yield 3.5 g (77%, yield) white solid product named as PI-3.

2. Characterizations

1) 1 H NMR spectrum of the radiation curable hyperbranched polyimide PI-3 in DMSO-d6 was shown in Figure 4. The peak assignments were also shown in Figure 4. The peaks around 4.6 ppm were assigned to the four methylene protons (- OCH2CH2O-) of the HEA unit indicating successful grafting of HEA.

2) Solubility The radiation curable hyperbranched polyimide PI-3 was well soluble in DCM, THF, DMAc, NMP, DMF and DMSO.

3) Miscibility

The radiation curable hyperbranched polyimide PI-3 showed good miscibility with vinyl methyl oxazolidinone (Vmox), 4-acryloylmorpholine (ACMO) and Ultracur3D® ST 45.

Example 4:

1. Synthesis of a radiation curable hyperbranched polyimide (PI-4) i) synthesis of an amine-terminated hyperbranched polyamic acid

A 0.5 mmol aliquot of TAMPB and 2 mmol TrMPD were dissolved in 15 mL of DMAc in a 250 mL thoroughly dried three-neck flask under N₂ flow. The contents were stirred with a magnetic stirring bar at room temperature, and 2.5 mmol of ODPA in 15 mL of DMAc was added dropwise through a syringe over 2 h. After the addition was finished, the reaction mixture was further stirred at room temperature for 10 h. The resulting hyperbranched polyamic acid homogenous solution was directly used for next step reaction. ii) synthesis of trimellitic anhydride-modified hyperbranched polyamic acid

0.55 mmol of trimellitic anhydride (TMAN) was added in one portion to the solution obtained in step (i) and the reaction mixture was stirred at room temperature for additional 10 h. iii) chemical imidization

A mixture of 2.4 g of trimethylamine (catalyst) and 2.4 g of acetic anhydride was added dropwise to the solution mixture of step (ii), and the reaction mixture was stirred at room temperature and 60 °C for 3 h and 5 h, respectively. After cooling to room temperature, the mixture was poured into 200 mL (24 mmol HCI) dilute hydrochloric acid solution and the precipitate was dried in vacuo. The dry solid was re-dis- solved in 10 mL of DMAc and added dropwise into 50 mL (0.6 mmol HCI) dilute hydrochloric acid solution. The precipitate was collected by filtration and dried in vacuo at 60 °C to yield 1.1 g (92%, yield) white solid product. iv) synthesis of a radiation curable hyperbranched polyimide

1.1 g (0.45 mmol carboxyl groups) of the carboxyl-terminated hyperbranched polyimide (product of step (iii)), 0.21 g (158 mmol) of 2-hydroxyethyl acrylate (HEA), 8 mg (0.04 mmol) of DMAP and 6 mL of NMP were added to a completely dried 3-neck flask. The reaction mixture was magnetically stirred at 0 °C under nitrogen atmosphere. DCC (0.28 g, 1.9 mmol) was added to the reaction flask in three batches. The reaction mixture was stirred at room temperature for 24 h to carry out Steglich esterification. Afterwards, the mixture was filtered and the filtrate was precipitated from Et20. The dissolution-precipitation was repeated three times to remove any impurities. The finally formed precipitate was dried in vacuo at 30 °C to yield 0.81 g (74%, yield) white solid product named as PI-4.

2. Characterizations

1) 1 H NMR spectrum of the radiation curable hyperbranched polyimide PI-4 in DMSO-d6 was shown in Figure 5. The peak assignments were also shown in Figure 5. The peaks around 4.6 ppm were assigned to the four methylene protons (- OCH2CH2O-) of the HEA unit indicating successful grafting of HEA.

2) Solubility

The radiation curable hyperbranched polyimide PI-4 was well soluble in DCM, THF, DMAc, NMP, DMF and DMSO.

3) Miscibility

The radiation curable hyperbranched polyimide PI-4 showed good miscibility with vinyl methyl oxazolidinone (Vmox), 4-acryloylmorpholine (ACMO) and Ultracur3D® ST 45.

Example 5:

1. Synthesis of a radiation curable hyperbranched polyimide (PI-5) i) synthesis of an amine-terminated hyperbranched polyamic acid A 14.1 mmol aliquot of TAMPB was dissolved in 90 mL of DMAc in a 500 mL thoroughly dried three-neck flask under N2 flow. The contents were stirred with a magnetic stirring bar at room temperature, and 9.88 mmol of 6FDA in 140 mL of DMAc was added dropwise through a syringe over 6 h. After the addition was finished, the reaction mixture was further stirred at room temperature for 10 h. The resulting hyperbranched polyamic acid homogenous solution was directly used for next step reaction. ii) synthesis of trimellitic anhydride (TMAN) and Maleic anhydride (MA)-modified hyperbranched polyamic acid 11.3 mmol of trimellitic anhydride (TMAN) was added in one portion to the solution obtained in step (i) and the reaction mixture was stirred at room temperature for additional 3 h. Then, 13.6 mmol of maleic anhydride (MA) was added in one portion and the reaction mixture was stirred at room temperature for additional 12 h. iii) chemical imidization

A mixture of 17.0 g of trimethylamine (catalyst) and 17.0 g of acetic anhydride was added dropwise to the solution mixture of step (ii), and the reaction mixture was stirred at room temperature and 60 °C for 3 h and 5 h, respectively. After cooling to room temperature, the mixture was poured into 2 L (17 mmol HCI) dilute hydrochloric acid solution and the precipitate was dried in vacuo. The dry solid was re-dissolved in 40 mL of DMAc and added dropwise into 400 mL (12 mmol HCI) dilute hydrochloric acid solution. The precipitate was collected by filtration and dried in vacuo at 60 °C to yield 12.1 g (93%, yield) white solid product. iv) synthesis of a radiation curable hyperbranched polyimide

9.35 g (8 mmol carboxyl groups) of the carboxyl-terminated hyperbranched polyimide (step iii product), 1.11 g (9.6 mmol) of 2-hydroxyethyl acrylate (HEA), 97 mg (0.8 mmol) of DMAP and 50g of DCM were added to a completely dried 3-neck flask. The reaction mixture was magnetically stirred at 0 °C under nitrogen atmosphere. EDC- HCI (2.30 g, 12 mmol) was added to the reaction flask in three batches. The reaction mixture was stirred at room temperature for 24 h to carry out Steglich esterification. Afterwards, the mixture was distilled at 30 °C under reduced pressure to remove the solvent and dissolved in 78 g THF. The mixture was filtered and the filtrate was precipitated from H2O. The dissolution-precipitation was repeated three times to remove any impurities. The finally formed precipitate was dried in vacuo at 30 °C to yield 6.9 g (70%, yield) white solid product named as PI-5.

Examples 1A, 1B, 2A, 2B, 2C, 3A, 3B, 4A and 4B

1. Preparation of the curable liquid compositions

The curable liquid compositions of examples 1A, 1 B, 2A, 2B, 2C, 3A, 3B, 4A and 4B were prepared by adding all components in amounts as shown in tables 1 and 2 into a plastic vial and mixing by speed-mixer at 2000RPM for 10 minutes at 25°C. The amounts in tables 1 and 2 were provided in parts by weight. 2. Preparation of the 3D-printed objects

All of the curable liquid compositions were printed by Miicraft DLP 3D respectively and post-treated by UV irradiation and thermal treatment, to obtain 3D-printed objects. The properties of the 3D-printed objects were shown in tables 1 and 2. The de- tailed process conditions were listed in Table 3. Examples 1A, 2A, 3A and 4A were comparative examples (compositions without polyimide component)

The photograph of the 3D-printed object obtained from example 1B was provided in figure 1.

Table 1

Table 2

The cured materials exhibited good mechanical properties. Comparing with comparative examples (composition without polyimide component), the tensile strength of the cured materials of the examples 1 B, 2B, 2C, 3B and 4B exhibited obviously increase.

The cured material of the examples had higher glass transition temperature and Heat Deflection Temperature (HDT) which indicated better thermal stability of materials.

Table 3. 3D-printing stages and parameters of Miicraft DLP 3D

Claims

1. A radiation curable liquid composition comprising

(2) At least one reactive component; and

(3) At least one photo-initiator.

2. The radiation curable liquid composition according to claim 1 , wherein the hyperbranched polymer is A_xB_y type, where x is at least 1 and y is at least 2.

3. The radiation curable liquid composition according to claim 1 or 2, wherein the radiation curable hyperbranched polymer containing polyimide moiety is a radiation curable hyperbranched polyimide.

4. The radiation curable liquid composition according to claim 3, wherein the radiation curable hyperbranched polyimide is derived from dianhydride (a), triamine (b), optional diamine (c) and a compound having one anhydride group and one or more carboxyl group (d), and has a radiation curable group, wherein the dianhydride (a) has the following structure:

wherein X is a linking group; and each Ri and R2 can be the same or different and independently selected from hydrogen, Ci-Ce alkyl, Ci-Ce alkoxy, C3-C10 cycloalkyl, C4-C16 cycloalkyl alkyl, C4-C16 alkyl cycloalkyl, C3-C10 cycloalkoxy, C4-C16 cycloalkyl alkoxy, Ce-Cw aryl, C7-C16 arylalkyl, C7-C16 alkylaryl, Ce-Cw aryloxy and 5-10-membered hetaryl.

5. The radiation curable liquid composition according to claim 4, wherein Ar is selected from an cycloaliphatic ring with 4 to 8 carbon atoms, or a ring system having at least two Ce-Cw aromatic rings, preferably Ar is selected from a cycloaliphatic ring with 4 to 8 carbon atoms, or a ring system having 2 to 4 Ce-C aromatic rings, preferably the aromatic rings are connected with linking structure Y selected from -O-, -S-, -CO- (carbonyl), -SO₂- (sulfonyl), Ci-Ce alkylene, and Ci-Ce alkylene interrupted with one or more heteroatoms or heteroatoms groups selected from -O-, -S-, -CO- (carbonyl) and -SO₂- (sulfonyl), wherein one or more hydrogen atoms in the alkylene can be further replaced with F or CF3.

6. The radiation curable liquid composition according to claim 4 or 5, wherein Ar is selected from the following group: a cycloaliphatic ring with 4 to 8 carbon atoms;

Y is as defined in claim 5.

7. The radiation curable liquid composition according to any of claims 4 to 6, wherein each Ri and R₂ can be the same or different and independently selected from hydrogen, C1-C4 alkyl, Ci- 04 alkoxy, C4-C6 cycloalkyl, C4-C10 cycloalkyl alkyl, C4-C10 alkyl cycloalkyl, C5-C10 cycloalkoxy, C5-C10 cycloalkyl alkoxy, Ce-Cw aryl, C7-C14 arylalkyl, C7-C14 alkylaryl and Ce-Cw aryloxy, preferably each R1 and R₂ can be the same or different and independently selected from hydrogen, C1-C4 alkyl and phenyl, more preferably one of R1 and R₂ on each phenyl is hydrogen.

8. The radiation curable liquid composition according to any of claims 4 to 7, wherein X is selected from -O-, -S-, -CO- (carbonyl), -SO₂- (sulfonyl), Ci-Ce alkylene, and Ci-Ce alkylene interrupted with one or more heteroatoms or heteroatoms groups selected from -O-, -S-, -CO- (carbonyl) and -SO₂- (sulfonyl), preferably selected from -O-, -S-, -CO- (carbonyl), -SO₂- (sulfonyl) and C1-C4 alkylene, most preferably -O-.

9. The radiation curable liquid composition according to any of claims 4 to 8, wherein the compound having one anhydride group and one or more carboxyl group (d) has 7 to 16 carbon atoms, preferably selected from 1 ,2, 4-benzenetricarboxylic anhydride, 1 ,2,4-naphthalenetricar- boxylic anhydride, 1 ,2,4-butanetricarboxylic anhydride, 1 ,2,5-hexanetricarboxylic anhydride, 1 ,2,4-cyclohexanetricarboxylic anhydride, or combination thereof.

10. The radiation curable liquid composition according to any of claims 4 to 9, wherein the radiation curable group is selected from an ethylenically unsaturated functional group, an epoxy group, or the mixture thereof.

11. The radiation curable liquid composition according to any of claims 4 to 10, wherein the diamine (c) is selected from aliphatic diamine, cycloaliphatic diamine, aromatic diamine, aliphatic- aromatic diamine, cycloaliphatic-aromatic diamine, aliphatic-cycloaliphatic diamine and the combination thereof; preferably the diamine has the formula of NH₂-R^N-NH2, wherein wherein the radical R^N is a hydrocarbyl having 2 to 40 carbon atoms, more preferably having 2 to 30 carbon atoms, for example 2 to 20 or 3 to 20 carbon atoms, preferably R^N is a linear or else cyclic divalent hydrocarbyl, aliphatic or else aromatic divalent hydrocarbyl.

12. The radiation curable liquid composition according to any of claims 4 to 11 , wherein the triamine (b) and diamine (c) are primary amines.

13. The radiation curable liquid composition according to any of claims 4 to 12, wherein the molar ratio of anhydride groups of dianhydride (a) to total amino groups of triamine (b) and optional diamine (c) is in the range from 0.4:1 to 0.99:1.

14. The radiation curable liquid composition according to any of claims 4 to 13, wherein the radiation curable hyperbranched polyimide is formed by reacting dianhydride (a), triamine (b) and optional diamine (c), and capping with compound having one anhydride group and one or more carboxyl group (d) and further grafting with the radiation curable group.

15. The radiation curable liquid composition according to any of claims 4 to 14, which has the following building block:

(IV) wherein Ri, R₂, X, Ar are as defined in any of claims 4 to 14;

A is a 5-7-membered ring comprising the CO-N-CO moiety or 9-13-membered fused ring comprising the CO-N-CO moiety; each R3 is the radiation curable group, preferably each R3 is independently selected from an ethylenically unsaturated functional group, an epoxy group, or the mixture thereof.

16. The liquid radiation-curable composition according to any of claims 1 to 15, wherein the amount of component (1) is in the range from 0.1 to 50 wt%, preferably from 1 to 40 wt%, based on the total weight of the radiation curable liquid composition.

17. The radiation curable liquid composition according to any of claims 1 to 16, wherein the reactive component (2) is a radiation-curable reactive component, preferably comprises at least one oligomer and/or at least one monomer containing at least one radiation curable group selected from an ethylenically unsaturated functional group, an epoxy group, or the mixture thereof.

18. The radiation curable liquid composition according to any of claims 1 to 17, wherein the functionality of the reactive component (2) is in the range from 1 to 12, preferably from 1 to 8.

19. The radiation curable liquid composition according to any of claims 1 to 18, wherein the amount of the reactive component (2) is in the range from 10 to 99.8 wt.%, preferably from 20 to 99 wt.%, based on the total weight of the radiation curable liquid composition.

20. The radiation curable liquid composition according to any of claims 1 to 19, wherein the amount of the photo-initiator (3) is in the range from 0.1 to 10 wt.%, preferably from 0.1 to 5 wt.% or from 0.5 to 5 wt.%, based on the total weight of the radiation curable liquid composition.

21. The radiation curable liquid composition according to any of claims 1 to 20, wherein the viscosity of the radiation curable liquid composition is no more than 2000 cps or in the range from 150 to 2000 cps measured according to DIN EN ISO 3219 at 23°C.

22. A process of forming 3D-printed object, comprising using the radiation curable liquid composition according to any of claims 1 to 21.

23. The process according to claim 22, wherein the process comprises the steps of: (p-i) forming a layer of the radiation curable liquid composition;

(p-iii) introducing a new layer of the radiation curable liquid composition onto the cured layer; (p-iv) applying radiation to the new layer of the radiation curable liquid composition to form a new cured layer; and

(p-v) repeating steps (iii) and (iv) until the 3D object is manufactured.

24. A 3D-printed object formed from the radiation curable liquid composition according to any of claims 1 to 21 or obtained by the process according to any of claim 22 or 23.

25. Use of the radiation curable liquid composition according to any of claims 1 to 21 in 3D- printing.