Resin Composition for 3D Printing

Abstract

This application relates to a resin composition for 3D printing, the resin composition comprising a) at least one curable oligomer or prepolymer resin component (compound B), and b) a reactive diluent (compound A) having one or more chemical substances that are alicyclic compounds according to formula (I): (I).

Description

[0001] This invention relates to a resin composition for 3D printing and a method for manufacturing objects by 3D printing.

[0002] Reactive diluents are low-molecular-weight organic molecules that play a vital role in fields such as coatings, adhesives, and additive manufacturing. They contain monomers to be mixed into resin compositions to reduce their viscosity and improve processability, and during induced polymerization (i.e., curing), the resin composition undergoes a covalent reaction with the polymerized and cured resin composition, becoming part of the final polymer network of the cured matrix.

[0003] This invention employs a specific class of polymerizable monomers as reactive diluents, suitable for high-temperature processes (>40°C), such as stereolithography. In addition to low volatility, this specific reactive diluent also exhibits low water absorption, high reactivity, and improved (thermo)mechanical properties (e.g., higher TV). g ).

[0004] Isoborneol methacrylate (IBMA) and 2-hydroxyethyl methacrylate (HEMA) are two commonly used reactive diluents in industry, but they do not meet all the criteria for the ideal reactive diluent used in this invention. HEMA exhibits low reactivity due to delayed gelation and high water absorption due to its hydrophilic hydroxyl groups, thereby impairing the mechanical properties of the polymer network through polymerization of the resin composition. Furthermore, both molecules are highly volatile, resulting not only in a strong, unpleasant odor but also posing health risks to users, especially when used in high-temperature 3D printing processes.

[0005] Several papers in the literature aim to address the aforementioned issues. For example, vanillin, eugenol (ChemSusChem 2012, 5, 1291, ACS Sustainable Chem. Eng. 2017, 5, 8876); carvacrol, thymol, menthol (ACS Sustainable Chem. Eng. 2020, 8, 17234); terpinenol, furoic acid (Polymer 2019, 11, 1815); mandelate (US20160347960A1); benzoate (JP2018076435A) and maleate (JP2017110154A) are methacrylated to produce reactive diluents with low volatility at room temperature, thereby obtaining high T g The polymer. However, its volatility and dilution properties at higher temperatures remain unresolved.

[0006] Methacrylated isopropylglycerin (WO 2018146258A1) and tricyclodecaneethanol mono(meth)acrylate (US2018194885A1) have also been proposed as potential low-volatility reactive diluents. However, in addition to the potential for high volatility at higher temperatures, the polymers involved may have low TV. g (Below 90°C).

[0007] For example, in WO 2022 / 272142A1, (meth)acrylated derivatives of eugenol, vanillin, or guaiacol derivatives are proposed as polymerizable monomers with low vapor pressure at high temperatures (>60°C), however, in some cases these compounds may be solids at around room temperature (melting point (mp) >40°C).

[0008] 2-Hydroxycyclohexyl methacrylate (HCMA) is a low molecular weight alicyclic methacrylate that has been used as a reinforcing agent in the preparation of hydrogels. Results show that HCMA exhibits high reactivity, and when added to hydrogel formulations along with 2-hydroxyethyl methacrylate (HEMA), materials with improved mechanical properties are obtained compared to hydrogels containing only HEMA. Besides its applications in hydrogels, HCMA has also found potential in other fields. For example, HCMA has been used to prepare adhesives, coatings, or films. HCMA has also been used as a precursor for the pre-synthesis of urethane methacrylates, which can then be polymerized to form adhesives. This is disclosed in CN103382382.

[0009] In this disclosure, a reactive diluent refers to a low molecular weight, polymerizable, monofunctional monomer that reduces the viscosity of another component (e.g., a polymer, prepolymer, or oligomer). Reactive diluents, as used herein, can be incorporated into a formulation and become part of the resulting polymer upon curing (thermopolymerization and / or photopolymerization). Therefore, an ideal reactive diluent should be liquid at room temperature and have low viscosity, exhibiting high reactivity with the resin composition, low volatility, and high stability at processing temperatures. Since these molecules become an integral part of the polymer network once the resin composition is cured by polymerization, it is also extremely important that the reactive diluent possesses good (thermo)mechanical properties (e.g., a high glass transition temperature) to meet the requirements of the cured resin composition.

[0010] As used herein, a polymer refers to a molecule composed of a large number of repeating structural units (equal to or more than 10 repeating units, and typically equal to or more than 50 or 100 repeating units) linked by covalent bonds and having a high molecular weight (e.g., equal to or greater than 5000 Da, 10000 Da, or 20000 Da). In this disclosure, the term "polymer" can refer to a homopolymer obtained by the polymerization of a single monomer, or a copolymer obtained by the polymerization of two or more different types of monomers.

[0011] As used herein, an oligomer is a molecule composed of a smaller number of covalently linked repeating structural units (less than a polymer, i.e., less than 10 structural units) and a smaller molecular weight (less than 5000 Da) than a polymer, which is polymerized from one or more monomers.

[0012] As used herein, a prepolymer is a polymer or oligomer that can be further polymerized due to the presence of available reactive groups.

[0013] As used herein, the term "teleclaw oligomer" refers to an oligomer that contains a reactive terminal group at each available chain end, and is therefore difunctional, trifunctional, or tetrafunctional, or even has a higher number of functional reactive groups and their terminals. The reactive groups can be the same or different groups.

[0014] As used herein, an initiator is a compound that can generate free radicals, thereby leading to polymerization. This initiator can be a photoinitiator (i.e., a compound that generates free radicals when exposed to UV or visible light) or a thermal initiator (a molecule that forms free radicals when heated above a certain activation temperature).

[0015] As used herein, the term “molecular weight” refers to the number-average molecular weight (Mn) determined by gel permeation chromatography (GPC) or size exclusion chromatography (SEC), calibrated using polystyrene standards in a suitable solvent (such as tetrahydrofuran).

[0016] The object of this invention is to provide a resin composition for 3D printing having a reactive diluent of an alicyclic compound (referred to as Compound A), which can be used to reduce the viscosity of at least one curable oligomer or prepolymer resin component (referred to as Compound B), thereby improving its processability. More specifically, to overcome the problems associated with the use of reactive diluents in common applications, the new polymerizable monomer has low volatility, making it suitable for high-temperature processes (>40°C), and provides good (thermo)mechanical properties (such as improved T... g Materials with (glass transition temperature) and high toughness.

[0017] To achieve this objective, the resin composition mentioned at the beginning of this invention comprises:

[0018] a) at least one curable oligomer or prepolymer resin component (compound B), and

[0019] b) A reactive diluent (compound A) having one or more chemical substances that are alicyclic compounds according to formula (I):

[0020]

[0021] (Formula I)

[0022] in:

[0023] n is an integer between 1 and 5;

[0024] R 1 It is hydrogen or methyl;

[0025] X is either -O- or -NR2-;

[0026] R 2 It is H or alkyl;

[0027] R 3 R 4 R 5 and R 6 Independently, it is H, a straight-chain or branched C1-C20 aliphatic group or a C5-C8 alicyclic group; or R 3 and R 4 All are carbonyl groups and / or R 5 and R 6 All are carbonyl groups;

[0028] Y is carbon, oxygen, sulfur, sulfone, or it may not exist.

[0029] Z is a carbonyl group, or it can form a carbonate (-CO-O-) or carbamate group (-CO-NR). 8 (or does not exist);

[0030] R 7 R 8 Independently, it is H, a straight-chain or branched C1-C20 aliphatic group, a C5-C8 alicyclic group, a heterocyclic group (such as tetrahydrothiophene), or a substituted or unsubstituted aromatic group, wherein the substituent of the aromatic group can be H, a straight-chain or branched C1-C10 aliphatic group, a methoxy or ethoxy group, or a halogen such as F, Cl, Br or I.

[0031] The resin compositions of the present invention exhibit improved (thermo)mechanical properties (e.g., T). gThe compound A exhibits low crystallinity due to the alicyclic moiety of its adjacent polymerizable (meth)acrylate unit. These outstanding properties suitable for reactive diluents are based on the reduced rotational freedom of reactive diluents as defined by the alicyclic compound A of claim 1. A characteristic aspect of the diluent class disclosed according to Formula I is its alicyclic nature and the resulting substitution pattern—asymmetric—which gives compound A a low crystallinity, making these compounds particularly suitable as reactive diluents. The readily synthesizable availability of such reactive diluents according to Formula I, achieved via an efficient ring-opening step with an epoxide precursor, is another key advantage of this disclosed diluent class, making it particularly interesting for industrial scale-up. Furthermore, these reactive diluents exhibit higher molar masses, especially when R... 7 Unlike H, this produces a diluent with low volatility. Therefore, this type of diluent is particularly suitable for 3D printing at high temperatures (e.g., 40-150 °C).

[0032] In formula (I), n is preferably 1 or 2, resulting in reactive diluents with 5- or 6-membered cyclic structures, respectively. These compounds are preferred because precursor molecules are more readily available and the overall synthesis of such compounds is easier to achieve.

[0033] In formula (I), when Y is absent, n is preferably 2 or 3, resulting in reactive diluents with 5- or 6-membered alicyclic cyclic structures, respectively. These compounds are preferred because precursor molecules are more readily available and the overall synthesis of such compounds is easier to achieve.

[0034] In a preferred embodiment of the invention, the polymerizable oligomer referred to as component B may be (meth)acrylate, (meth)acrylamide, vinyl ester, vinyl ether, vinyl amide, vinyl carbonate, vinyl carbamate, styrene, itaconic acid ester, fumarate, maleimide, and derivatives thereof. These disclosed categories of functional units readily undergo free radical chain-growth polymerization and therefore tend to copolymerize with reactive diluents of Formula I according to the invention, typically forming polymer networks.

[0035] Preferably, the at least one curable oligomer or prepolymer resin component comprises one or more monofunctional or polyfunctional chemical substances. By including polyfunctional chemical substances undergoing free radical chain growth polymerization, a crosslinking reaction occurs, resulting in the formation of a polymer network.

[0036] Preferably, the molecular weight of the at least one curable oligomer or prepolymer resin component is higher than 450 g / mol, more preferably higher than 1000 g / mol, and even more preferably higher than 2000 g / mol. Using such curable, high molecular weight oligomers (preferably T...) g(Below environmental conditions) a robust photopolymer network is generated by introducing long, flexible linkers. Here, when a higher content of monofunctional reactive diluents is used in the resin formulation instead of crosslinking monomers to process such high molecular weight oligomers, toughness is significantly improved, but heat resistance and strength are often compromised. Therefore, using higher molecular weight, exhibiting T... g Photocurable oligomers above environmental conditions will critically improve printability and the material properties of the final photopolymer. While (thermo)mechanical properties such as T... g The modulus and strength will be enhanced, but toughness may be compromised. In a preferred embodiment, such oligomer compositions may comprise two, three, or more different oligomers.

[0037] Preferably, the reactive diluent has been used as a solvent in the synthesis of the at least one curable oligomer or prepolymer resin component.

[0038] Preferably, based on the total weight of the at least one curable oligomer or prepolymer resin component and the reactive diluent, the amount of reactive diluent ranges from 5 wt% to 80 wt%, preferably 5 wt% to 60 wt%, more preferably 5% to 50%, and even more preferably 5 wt% to 40 wt%. Higher amounts of reactive diluent result in better printability and easier resin handling. In most cases, it is beneficial to keep the reactive diluent at the lowest possible level (e.g., from 5 wt% to 40 wt%) because the primary network-forming component is the multifunctional oligomer employed, which produces a robust polymer network.

[0039] Preferably, based on the total weight of the at least one curable oligomer or prepolymer resin component and the reactive diluent, the amount of the at least one curable oligomer or prepolymer resin component ranges from 20 wt% to 95 wt%, preferably 40 wt% to 95 wt%, more preferably 50 wt% to 95 wt%, and even more preferably 60 wt% to 95 wt%. While higher oligomer content tends to produce high-performance materials with enhanced toughness, printability may be affected.

[0040] Preferably, the reactive diluent experiences a weight loss of less than 10%, more preferably less than 5%, and more preferably less than 1% after being placed at temperatures up to 50°C for 24 hours. Compared to prior art diluents (such as HEMA or isobornyl methacrylate), the reactive diluent (compound A) disclosed according to Formula I exhibits lower volatility and better printability at high temperatures. Low-volatility reactive diluents are crucial for ensuring uniform performance throughout the printing process, while also ensuring good operational safety. Furthermore, if the reactive diluent in the resin composition does not react during polymerization and happens to be trapped in the final polymer network, the disclosed low-volatility reactive diluent exhibits a reduced migration tendency due to its molecular size. This reduced migration tendency is beneficial for applications in the biomedical field.

[0041] Preferably, the reactive diluent has a viscosity of 1 to 100 mPa·s at a processing temperature between 30 and 150°C, more preferably 1 to 50 mPa·s, and even more preferably 1 to 20 mPa·s. Generally, it is expected that the lower the viscosity of the reactive diluent, the better the dilution performance of the final resin. In particular, compound A according to formula I is expected to exhibit a relatively high viscosity under ambient conditions, but a low viscosity within the preferred high-temperature range of 30 to 150 °C. This makes the disclosed compound A particularly suitable as a reactive diluent for high-temperature 3D printing in the range of 30 to 150 °C.

[0042] Preferably, in formula (I), R 7 Select from the following structures, where the dashed lines indicate the positions of the bonds connected to Z in equation (I):

[0043] .

[0044] According to a preferred embodiment of the invention, the reactive diluent of general formula (I) is selected from the group consisting of the following compounds:

[0045] 2-Hydroxycyclohexyl methacrylate (Ex 1)

[0046]

[0047] 2-(cyclohexylcarbonyloxy)cyclohexyl methacrylate (Ex 2)

[0048]

[0049] 2,2-Dimethylpropionic acid 2-(isopropenylcarbonyloxy)cyclohexyl ester (Ex 3)

[0050]

[0051] 2-(benzylcarbonyloxy)cyclohexyl methacrylate (Ex 4)

[0052]

[0053] 2-Ethylhexanoic acid 2-(isopropenylcarbonyloxy)cyclohexyl ester (Ex 5)

[0054]

[0055] Preferred compound A as R 7 Exhibiting hydrophilic functional groups (e.g., Ex 1, where Z is absent and R 7 (e.g., H), additional alicyclic groups (e.g., Ex 2, where Z is carbonyl and R is H), 7 (e.g., cyclohexyl), macro- or branched aliphatic (e.g., Ex 3, where Z is carbonyl and R is...) 7 It is tert-butyl; and Ex 5, where Z is carbonyl and R 7 (Ethyl-pentyl) or a "quasi" aromatic moiety (e.g., implying the introduction of a flexible methylene spacer, Ex 4, where Z is a carbonyl group and R is an ethyl-pentyl group) or a "quasi" aromatic moiety (e.g., meaning the introduction of a flexible methylene spacer, Ex 4, where Z is a carbonyl group and R is an ethyl-pentyl group). 7 (Benzyl), all of which result in reduced volatility and low crystallization tendency, making these disclosed compounds ideal candidates for preferred reactive diluents used in the resin compositions of the present invention for 3D printing.

[0056] This invention achieves its purpose for all reactive diluents as defined in claim 1. Therefore, this invention is not necessarily committed to using 2-hydroxycyclohexyl methacrylate (HCMA, Ex 1) as a reactive diluent.

[0057] Preferably, the resin further comprises at least one photoinitiator, preferably suitable for free radical polymerization under photoexcitation, preferably excited in a wavelength spectrum of 150 nm to 1000 nm, more preferably between 200 nm and 550 nm, and preferably in an amount of 0.01 wt% to 10 wt%, preferably 0.1 wt% to 7 wt%, more preferably 0.2 wt% to 5 wt%, based on the total weight of at least one curable oligomer or prepolymer resin component and reactive diluent in the composition. This means that the photoinitiator present in the resin composition can be photoactivated and effectively initiate the polymerization of the photocurable component in the formulation during 3D printing. Photoinitiated polymerization (photopolymerization) is successful when the applied light wavelength is suitable for activating the photoinitiator and has sufficient power. In addition to the light being sufficient for the photoinitiator, the overall formulation (optionally including light-absorbing monomers or additives) may not interfere with the interaction between the emitted light and the photoinitiator. The light used herein includes any wavelength and power capable of initiating polymerization. The preferred light wavelength is between 150 nm and 1000 nm, and even more preferably between 200 nm and 550 nm. Any suitable NIR, UV, or visible light source can be used, including but not limited to lasers, LEDs, or broadband mercury lamps. The light source can emit broadband or narrowband spectra, or combinations thereof. The light source can emit continuous or pulsed light during single or repeated exposures, which can also be varied by the exposure time or intensity. A suitable and increased process temperature will increase the reactivity of the system, thereby enhancing the photoinduced structuring process. Adjusting the above parameters and variables will lead to an optimized scheme for performing the photopolymerization reaction, achieving optimal 3D processing through photolithography-based additive manufacturing technology.

[0058] Preferably, the resin further comprises a thermal initiator and / or a thermal curing catalyst, which are suitable for initiating a thermally triggered post-curing step, or can be used to implement a secondary curing mechanism to produce a dual-cured or hybrid network (e.g., an interpenetrating network).

[0059] Recently, focus has been placed on hybrid resin systems, which consist of one or more additional material concepts that differ from the photopolymer networks used in the photostructuring steps of photolithography-based additive manufacturing (L-AMTs). This promising hybrid material concept shows great potential for forming tough photopolymer resins for additive manufacturing and can produce photopolymer materials with both high toughness and heat resistance. Hybrid resin systems can be defined as resin materials exhibiting various curing steps triggered by different pulses (e.g., a photocuring step followed by a thermocuring step – US2016 / 0160077 A1) and / or materials exhibiting multiple curing mechanisms (e.g., combined radical and cationic curing mechanisms or various radical curing mechanisms). The resulting photopolymer network is considered a mixture of a first component, a second component, or multiple further components, and is generally represented as a fully interpenetrating network (IPN), a semi-IPN, a quasi-IPN, a dual network, or a polymer blend. To maintain photoreactivity and thus ensure processability in L-AMTs, formulations with effective amounts of the photocurable components are required to produce materials with sufficient green strength. Green strength is the mechanical strength of the material obtained after the photopolymer additive manufacturing step (e.g., measured by tensile or bending tests).

[0060] Preferably, the resin further comprises a second polymerizable system suitable as a dual-curing system. This means that, in addition to the previously described photopolymerization system, a second alternative system can be incorporated for a second thermal polymerization process. This second system preferably comprises a mixture of monomers, oligomers, or prepolymers containing a pair of functional groups suitable for thermal polymerization processes, including epoxy resins with amines or alcohols, oxetanes with amines or alcohols, isocyanates with alcohols, amines or carboxylic acids, amines with carboxylic acids, esters, anhydrides, aldehydes, acyl chlorides, alcohols with acyl chlorides or halides, click chemistry reactions such as alkynes-azides, Michael addition, Diels-Alder reactions, maleimide and citrate-imide derivatives with allyl and / or vinyl derivatives, olefins or alkynes with thiols, peroxides, and silicon polymerization reactions.

[0061] Preferably, the resin further comprises one or more components selected from the group consisting of polymerization initiators, polymerization inhibitors, solvents, fillers, antioxidants, pigments, dyes, surface modifiers, and flame retardants. The polymerization inhibitor is preferably a quinone, such as hydroquinone and benzoquinone, phenothiazine, diethylhydroxyamine, 4-tert-butylcatechol, butylated hydroxytoluene, pyrophenol, or TEMPO, and its amount is preferably 0.001 wt% to 1 wt%, more preferably 0.005 wt% to 0.5 wt%, and even more preferably 0.01 wt% to 1 wt%, based on the total weight of at least one curable oligomer or prepolymer resin component and reactive diluent.

[0062] To synthesize the reactive diluent contained in the resin composition of the present invention, a two-step synthetic method is used, which can start from the ring-opening reaction between an alicyclic epoxide and (meth)acrylic acid, using a quaternary ammonium salt as a catalyst. Preferred epoxide starting materials include: cyclopentene oxide, cyclohexene oxide, cycloheptene oxide, cyclooctene oxide, 7-oxabicyclo[4.1.0]heptane-2-one, 9-oxabicyclo[6.1.0]non-4-ene, vitamin K3 2,3-epoxide, 2-methyl-1,2-cyclohexene oxide, 3-methyl-1,2-cyclohexene oxide, 4-methyl-1,2-cyclohexene oxide, 4-vinyl-1-cyclohexene 1,2-epoxide, 7-oxabicyclo[4.1.0]heptane-3-carboxylic acid methyl ester, α-pinene oxide, limonene 1,2-epoxide, 6-oxabicyclo[3.1.0]hexane-3-one, 5-methyl-6-oxabicyclo[3.1.0]hexane-2-one, 3,4-epoxytetrahydrofuran, and 3,4-epoxytetrahydrothiophene-1,1-dioxide. These epoxide starting materials are represented by their structural formulas as follows.

[0063] .

[0064] The obtained hydroxy alicyclic (meth)acrylates can then be reacted with acyl chlorides, carboxylic anhydrides, chloroformates, or halogenated aliphatic compounds. Preferred components for this reaction include: trimethylacetyl chloride, cyclohexane carbonyl chloride, 2-ethylhexanoyl chloride, phenylacetyl chloride, hydrogenated cinnamoyl chloride, cinnamoyl chloride, 4-fluorophenylacetyl chloride, benzoyl chloride, phenoxyacetyl chloride, 4-methyl-1-cyclohexanecarboxylic acid, 1-methyl-1-cyclohexanecarboxylic acid, 4-chlorophenylacetyl chloride, propionyl chloride, p-tolueneacetyl chloride, isobutyryl chloride, isovaleryl chloride, acetyl chloride, cyclobutane carbonyl chloride, (4-tert-butylcyclohexyl)acetic acid, 4-tert-butylcyclohexanecarboxylic acid, cyclopropane carbonyl chloride, 3,3-dimethylbutyryl chloride, 2-furfuryl chloride, 3-furfuryl chloride, 2-thiophene carbonyl chloride, 5-methyl Furan-2-carbonyl chloride, 3-nitrobenzoyl chloride, cycloheptane carboxylic acid, hexanoic acid, octanoic acid, dodecanoic acid, pyrrole-3-carboxylic acid, 5-oxazole carboxylic acid, 1H-pyrazole-3-carboxylic acid, 1-bromoadamantane, 1-adamantane carboxylic acid, 1-adamantane acetic acid, 3,5-dimethyladamantane-1-carboxylic acid, 9-anthracarboxylic acid, 2-naphthyl acid, biphenyl-4-carboxylic acid, 4'-methoxybiphenyl-4-carboxylic acid, isobutyl chloroformate, ethyl chloroformate, isopropyl chloroformate, menthyl chloroformate, phenyl chloroformate, allyl chloroformate, methyl chloroformate, cholesterol chloroformate or cholesterol hemisuccinate, camphoryl chloride.

[0065] In a preferred alternative embodiment, a different two-step synthetic method starting with an amino alcohol is chosen for synthesizing the reactive diluent contained in the resin composition of the present invention, which yields (meth)acrylamide after reaction with (meth)acryloyl chloride. Preferred amino alcohols that may be involved in this reaction include: 2-aminocyclohexanol, 2-bromocyclopentanol, 2-aminocyclopentanol, and 1-amino-2-indanol.

[0066] The obtained hydroxy alicyclic (meth)acrylamide can then be reacted with acyl chlorides, carboxylic acids, acid anhydrides, chloroformates, or halogenated aliphatic compounds. Possible components for this reaction include: trimethylacetyl chloride, cyclohexane carbonyl chloride, 2-ethylhexanoyl chloride, phenylacetyl chloride, hydrogenated cinnamyl chloride, cinnamyl chloride, 4-fluorophenylacetyl chloride, benzoyl chloride, phenoxyacetyl chloride, 4-methyl-1-cyclohexane carboxylic acid, 1-methyl-1-cyclohexane carboxylic acid, 4-chlorophenylacetyl chloride, propionyl chloride, p-tolueneacetyl chloride, isobutyryl chloride, isovaleryl chloride, acetyl chloride, cyclobutane carbonyl chloride, (4-tert-butylcyclohexyl)acetic acid, 4-tert-butylcyclohexane carboxylic acid, cyclopropane carbonyl chloride, 3,3-dimethylbutyryl chloride, 2-furfuryl chloride, 3-furfuryl chloride, 2-thiophene carbonyl chloride, 5-methyl Furan-2-carbonyl chloride, 3-nitrobenzoyl chloride, cycloheptane carboxylic acid, hexanoic acid, octanoic acid, dodecanoic acid, pyrrole-3-carboxylic acid, 5-oxazole carboxylic acid, 1H-pyrazole-3-carboxylic acid, 1-bromoadamantane, 1-adamantane carboxylic acid, 1-adamantane acetic acid, 3,5-dimethyladamantane-1-carboxylic acid, 9-anthracarboxylic acid, 2-naphthyl acid, biphenyl-4-carboxylic acid, 4'-methoxybiphenyl-4-carboxylic acid, isobutyl chloroformate, ethyl chloroformate, isopropyl chloroformate, methyl chloroformate, phenyl chloroformate, allyl chloroformate, menthyl chloroformate, cholesterol chloroformate or cholesterol hemisuccinate, camphoryl chloride.

[0067] The resulting reactive diluent is preferably used in photopolymerization processes such as 3D printing and stereolithography. More specifically, such reactive diluents can be used as an alternative to 2-hydroxyethyl methacrylate (HEMA), exhibiting lower volatility, better (thermo)mechanical properties, and higher reactivity.

[0068] Another aspect of the present invention is a method for polymerizing a reactive diluent compound according to Formula I with at least one oligomer, telechelic oligomer or prepolymer to obtain a crosslinked polymer.

[0069] Preferably, the at least one curable oligomer or prepolymer resin component is a methacrylate resin, such as: aliphatic urethane di(meth)acrylate (e.g., Ebecryl 8811, X-851-1066, Ebecryl8809, Ebecryl 8408, Ebecryl 246, Miramer PU2100, Miramer SC2404, MiramerSC2565, Miramer PU2564, BR-571 MB, BR-541 MB, BR-7423GB, CN9001, CN965, CN981, CN8881 NS), ethoxylated bisphenol A di(meth)acrylate (e.g., Miramer 220, Miramer2301), polyether urethane (meth)acrylate (e.g., Br-541 MB, ... BR582H15), hydrophobic urethane (meth)acrylates (e.g., BRC-443), polyester urethane (meth)acrylates (e.g., BR744 BT), polyester di(meth)acrylates (e.g., CN2608A, CN704, CN790), modified epoxy di(meth)acrylates (e.g., CN2003EU), and oligomeric carbonate di(meth)acrylates.

[0070] The oligomers, telechelic oligomers, or prepolymers used in this invention can be not only difunctional, but also trifunctional, tetrafunctional, pentafunctional, hexafunctional, or even have more functional sites, or even have multiple functional sites at either end of the oligomer. Therefore, it can be not only linear, but also a branched polymer (e.g., star-shaped, dendritic, comb-shaped, or branched).

[0071] In a preferred embodiment, the alicyclic compound according to Formula I can also be mixed with other low molecular weight monofunctional monomers, such as (meth)acrylates, (meth)acrylamide, vinyl esters, and N-vinyl compounds. Some preferred monomers for mixing with the alicyclic compound according to Formula I are: isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, trimethylcyclohexyl (meth)acrylate, glyceryl formaldehyde (meth)acrylate, tricyclodecane methanol mono(meth)acrylate, 4-tert-butylcyclohexyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, cyclic trimethylolpropane formaldehyde (meth)acrylate, salicylic acid (meth)acrylate such as cyclopentyl 2-(methacryloyloxy)benzoate, cyclohexyl 2-(methacryloyloxy)benzoate, 2 2-(methacryloyloxy)benzoic acid-2-isopropyl-5-ethylcyclohexyl ester, 3-(methacryloyloxy)benzoic acid-2-isopropyl-5-methylcyclohexyl ester, 4-(methacryloyloxy)benzoic acid-2-isopropyl-5-methylcyclohexyl ester, 2-(methacryloyloxy)benzoic acid-3,3,5-trimethylcyclohexyl ester, 2-(acryloyloxy)benzoic acid-3,3,5-trimethylcyclohexyl ester, 2-(methacryloyloxy)benzoic acid-decahydronaphthalene-2-yl ester, 2-(methacryloyloxy)benzoic acid-1,3,3-trimethyl-2-bicyclo[2.2.1]heptane 2-(methacryloyloxy)benzoic acid-1,7,7-trimethyl-2-bicyclo[2.2.1]heptyl ester, 2-(methacryloyloxy)benzoic acid-bicyclo[2.2.1]heptane-2-ylmethyl ester, 2-(methacryloyloxy)benzoic acid-2-cyclohexylethyl ester, 2-(methacryloyloxy)benzoic acid benzyl ester, 4-(methacryloyloxy)benzoic acid benzoate, 3-(methacryloyloxy)benzoic acid-4-isopropylbenzyl ester, 2-(acryloyloxy)benzoic acid benzyl ester, 2-(methacryloyloxy)benzoic acid phenethyl ester, 4-(methacryloyloxy)benzoic acid benzyl ester 3-Methoxybenzyl benzoate (3-methoxybenzoic acid), 1-phenylethyl 2-(methacryloyloxy)benzoate, cycloheptanyl 4-((methacryloyloxy)methyl)benzoate and cyclohexylmethyl 2-(methacryloyloxy)benzoate, cholesterol ester (meth)acrylate, biphenyl acrylate (meth)acrylate, phenylacrylamide, diacetone acrylamide, tert-butylacrylamide, N-acryloylmorpholine, N-vinylpyrrolidone, N-vinylcaprolactam, N-vinylformamide, vinyl cinnamate, vinyl methyl oxazolidinone and methyl 2-(allyloxymethyl)acrylate.

[0072] In another preferred embodiment of the invention, the alicyclic compound according to formula (I) can also be mixed with other difunctional and polyfunctional (meth)acrylates and (meth)acrylamides (referred to herein as component C) having low molecular weights (below 500 g / mol) to obtain a crosslinked polymer. If desired, component C is added to obtain better processability and higher green strength. The polyfunctional monomers constituting component C are suitable for fast reaction rates and high crosslinking densities, improving heat resistance (e.g., higher Tg). g However, this usually reduces toughness.

[0073] Some examples of these (meth)acrylates and (meth)acrylamides are: ethylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, triglyceride di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, di(ethylene glycol) di(meth)acrylate, tri(ethylene glycol) diacrylate, 1,10-decanediol di(meth)acrylate, neopentyl glycol diacrylate, tricyclo[5.2.1.0] 2,6 Decanediethanol diacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, piperazine diacrylamide, N,N'-methylenebis(acrylamide), N,N'-bis(acryloyl)cystamine, N,N'-(1,2-dihydroxyethylene)bisacrylamide and bisphenol A di(meth)acrylate.

[0074] Based on the total weight of at least one curable oligomer or prepolymer resin component and reactive diluent in the composition, the amount of component C preferably ranges from 5 wt% to 60 wt%, more preferably from 5 wt% to 50 wt%, more preferably from 5 wt% to 40 wt%, and even more preferably from 5 wt% to 35 wt%.

[0075] The method of the present invention is preferably part of a high-temperature photolithography process, wherein the resin formulation of the present invention contains at least one photopolymerization initiator, preferably in an amount of 0.01 wt% to 10 wt%, more preferably 0.1 wt% to 7 wt%, and even more preferably 2.5 wt% to 5 wt%, based on the total weight of at least one curable oligomer or prepolymer resin component and reactive diluent in the composition. The photoinitiator should be suitable for free radical polymerization under irradiation, with a wavelength spectrum preferably between 150 nm and 1000 nm, more preferably between 200 nm and 550 nm. The photopolymerization method is particularly effective if the exposure wavelength is sufficient to activate the photoinitiator.

[0076] More preferably, this is part of an additive manufacturing process (such as 3D printing), and the mixture is heated before being mixed with a photoinitiator. In some embodiments of this process, the resin composition is heated to a desired process temperature, preferably between 30 and 150°C, more preferably between 35°C and 100°C, and even more preferably between 40°C and 90°C, and then exposed to light of an appropriate wavelength.

[0077] Preferred photoinitiators are Norrish type I photoinitiators, either alone or in combination, and are selected from the group consisting of: α-hydroxy ketones, phenyl glyoxylates, benzyl dimethyl ketal, α-amino ketones, mono- or diacylphosphine, phosphine oxide, mono-, di-, or tetraacylsilanes, germananes, stananes, and metallocenes. Some preferred examples are: 2-hydroxy-2-methylphenylacetone, 1-hydroxycyclohexylphenyl ketone, methyl phenyl glyoxylate, 2-benzyl-2-(dimethylamino)-4'-morpholinylbutanone, [1-(4-phenylthioylbenzoyl)heptylimino]benzoate, [1-[9-ethyl-6-(2-methylbenzoyl)carbazole-3-yl]ethaneylimino]acetate, 2,4,6-trimethylbenzoyl diphenylphosphine oxide (TPO), (2, Ethyl 4,6-trimethylbenzoyl)phenylphosphonate (TPO-L), phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide (BAPO), (3-benzoyl-2,4,6-trimethylbenzoyl)(phenyl)phosphonate, bis(4-methoxybenzoyl)diethylgermanane (BMDG), and bis(cyclopentadienyl)bis[2,6-difluoro-3-(1-pyrrolidinyl)phenyl]titanium and / or polymeric type I photoinitiators such as Ominpol TP.

[0078] Other preferred photoinitiators are Norrish type II photoinitiators. Some preferred examples are benzophenone (e.g., benzophenone, 4-methylbenzophenone, 4,4'-bis(diethylamino)benzophenone), benzoin, diketones (e.g., 9,10-phenanthraquinone, 1-phenyl-propane-1,2-dione, diacetyl or 4,4'-dichlorobenzoyl and / or its derivatives), and thioxanthones (e.g., chloropropoxythioxanthone, isopropylthioxanthone or 2,4-diethyl-9H-thioxanth-9-one). Such type II photoinitiators may preferably be used in combination with a co-initiator, such as a tertiary amine (e.g., aromatic tertiary amines such as N,N-dialkylaniline, p-toluidine or 3,5-dimethylaniline, p-N,N-dialkylamino-phenylethanol, carboxylic acid derivatives, benzaldehyde or triethanolamine).

[0079] In some of the disclosed contents of this implementation scheme, a combination of Norrish Type I and Type II may also be used.

[0080] In other embodiments of the disclosed process, the photopolymer material may undergo a secondary post-curing process. This post-curing process may be photoinduced and, optionally, thermally induced.

[0081] The preferred composition comprising component A, component B, component C and a photoinitiator according to the present invention can be selected such that:

[0082] Based on the total weight of components A and B in the formulation, the amount of photopolymerizing component A ranges from 5 wt% to 70 wt%, preferably from 5 wt% to 60 wt%, more preferably from 5% to 50%, and even more preferably from 5% to 40%.

[0083] Based on the total weight of components A and B in the formulation, the amount of photopolymerizing component B ranges from 30 wt% to 95 wt%, preferably 40 wt% to 95 wt%, more preferably 50 wt% to 95 wt%, and even more preferably 60 wt% to 95 wt%.

[0084] Based on the total weight of components A and B in the formulation, the amount of component C ranges from 5 wt% to 60 wt%, preferably from 5 wt% to 50 wt%, more preferably from 5 wt% to 40 wt%, and even more preferably from 5 wt% to 35 wt%.

[0085] Based on the total weight of components A and B in the formulation, the amount of photoinitiator ranges from 0.01 wt% to 10 wt%, more preferably from 0.1 wt% to 7 wt%, and even more preferably from 2.5 wt% to 5 wt%.

[0086] Another aspect of the present invention relates to a method for manufacturing objects by 3D printing, wherein a resin composition according to the first aspect of the invention undergoes: a) a light-induced structuring step, optionally followed by post-curing via secondary exposure, and

[0087] b) The subsequent heat-induced curing step.

[0088] In a preferred embodiment of the invention, a single compound may be selectively homopolymerized in a thermally induced curing step, resulting in the formation of a hybrid network. Preferred compounds for the thermally induced curing step include maleimide and citrileimide derivatives, epoxy derivatives, and allyl derivatives. Preferably, a thermal initiator, comprising amines, azo compounds, alkali salts, or peroxides, may be added to the thermally induced curing step, ranging from 0.01 wt% to 20 wt%, preferably from 0.1 wt% to 15 wt%, more preferably from 0.2 wt% to 10 wt%, based on the total weight of at least one curable oligomer or prepolymer resin component and a reactive diluent.

[0089] Preferably, the second heat-induced curing step is activated only when the formulation is heated (ideally at a temperature above 50°C), thereby keeping the formulation stable at room temperature.

[0090] The resin composition can also be mixed with polymerization initiators, polymerization inhibitors, solvents, fillers, antioxidants, pigments, dyes, surface modifiers, flame retardants, and mixtures thereof.

[0091] The polymerization inhibitor is preferably a quinone, such as hydroquinone and benzoquinone, phenothiazine, diethylhydroxylamine, 4-tert-butylcatechol, butylated hydroxytoluene, pyrophenol, or TEMPO, and is preferably 0.001 wt% to 1 wt%, more preferably 0.005 wt% to 0.5 wt%, and even more preferably 0.01 wt% to 1 wt%, based on the total weight of at least one curable oligomer or prepolymer resin component and the reactive diluent.

[0092] In photopolymer-based printing, photosensitive resin is locally irradiated at high resolution using a photolithography-based process, and the irradiated area solidifies to form a solid. This process can be performed in stages or continuously, building up a previously prepared three-dimensional structure. Here, the component typically sits on a build platform. After the 3D printing process is complete, the produced 3D component is contaminated with resin.

[0093] Following a successful 3D printing process, the component can undergo final processing or finishing. These processes are called post-processing and include a variety of downstream processes to achieve the final component's performance. One typical post-processing step here is cleaning. This can be done using centrifugal force, solvents as described in AT 525049 A4, turbulence, directed jetting, ultrasound, steam, aerosols, and / or, during pressure changes, using gases and / or directed airflows (e.g., compressed air, heated compressed air).

[0094] Following cleaning, one or more downstream processes are typically performed to obtain the final 3D assembly. Typical downstream processes include drying, post-curing, coating (e.g., metallic, semi-metallic, ceramic, and / or plastic coatings), mechanical post-treatment of the 3D assembly, and removal of any support structures that may be present, assembly processes, application of conductive tracks, insertion of contact pins, assembly coloring, and so on. The drying step can be performed in air or other atmospheres (such as nitrogen or argon) at room temperature, or at elevated temperatures, such as in an oven or belt oven, using various compressed air technologies and / or via directional hot air.

[0095] Post-curing can be a heat- and / or radiation-induced process (e.g., using a UV light source). The heat process can be carried out at temperatures between 40 and 400°C. In the case of degreasing and sintering or carbonization processes, the heat process can also be carried out at temperatures of several hundred degrees or even exceeding 1000°C. Heat exposure can be carried out in batches or continuously, for example in a belt furnace.

[0096] The same applies to radiation post-curing; it can be performed in batches or continuously, for example, in a radiation belt oven. All these post-curing steps can be performed in any order and any number of times to achieve the final properties of the 3D component.

[0097] The resin compositions of this invention can be used to manufacture various types of three-dimensional objects. Examples of applications for 3D printed objects include electronic, electrical and electromechanical components, connectors, housings, automotive and aerospace sectors, electric mobility, communications technology, computer technology, military technology, medical devices, medical technology, consumer products, the sports industry, the energy industry, printed electronics, and dental and orthodontic applications.

[0098] Example

[0099] All chemicals were purchased from chemical suppliers (ABCR, Merck, TCI, Carbosynth) and used without further purification. NMR spectra were recorded on a Bruker advanced Ultrashield 400. 1 H 400 MHz; 13 C 101MHz). Chemical shift (δ) is given in parts per million (ppm) and an internal standard of deuterated solvent is used. 1 H 7.26 ppm; 13 Correction was performed at C77.16 ppm. Proton multiplicity was represented by the following abbreviations: s (singleton), d (doublet), t (triplet), q (quartet), p (pentetet), m (multiplex), dd (doublet), dt (doubletuplet), dq (double quartet). Coupling constants (J) were expressed in Hertz (Hz). TLC (thin-layer chromatography) was performed using silica gel 60 aluminum plates containing a fluorescent indicator from Carl Roth, and detected by UV light (254 nm) or potassium permanganate staining (1.5 g KMnO4, 6.6 g K2CO3, 1.25 mL 10% NaOH, 200 mL H2O). Rapid column chromatography and vacuum drying chromatography were performed using industrial-grade silica gel (particle size 40-63 µm, 230-400 mesh) from Sulpeco.

[0100] Volatility can be assessed by weight loss after 24 hours, preferably less than 10%, more preferably less than 5%, and even more preferably less than 1% at the process temperature (between 30 and 150°C). To determine the volatility of a compound, a 25 mL flask (Ø 30 mm) containing approximately 2 g of the test compound is placed in a Memmert oven and placed at 50 °C and 80 °C for 24 hours. Volatility is determined as a percentage of weight loss (w / w).

[0101] Viscosity is another key parameter in the development of reactive diluents. To obtain an effective reactive diluent, monomers providing low viscosity are required. The viscosity is preferably between 5 and 100 mPa·s, more preferably between 5 and 50 mPa·s, and even more preferably between 5 and 20 mPa·s. The viscosity presented refers to a process temperature between 30 and 150°C. Viscosity is determined by rheology. Rheological measurements are performed using an Anton Paar MCR 102 rheometer equipped with a P-PTD 200 / GL Peltier glass plate and an H-PTD200 heating shroud. To measure rheological properties, a CP25 measurement system (a conical plate with a 2° angle and a 25 mm diameter) is used at a gap distance of 0.1 mm and a 60 s⁻¹ measurement time. -1 At a shear rate of 0.5°C, a temperature scan experiment was performed from 25-100°C. -1 .

[0102] Optical-DSC (differential scanning calorimetry) studies were performed using a Netzsch DSC 204 F1 system equipped with an autosampler coupled to an IC85 intracooler. The system was connected to an Omnicure LX500 controller with a 365 nm LED, and the power intensity on the sample was set to 17 mW cm⁻¹. -2 (Measurements were made using a Thorlabs SMC100 power meter and a corresponding S310C thermal power head). Test samples were mixed with 1% w / w TPO-L (a commercial photoinitiator) in a vortex mixer for 3 minutes, then 10 ± 2 mg was transferred to an open aluminum crucible. All experiments were conducted under a nitrogen atmosphere (flow rate = 20 mL / min) at 50°C, with the samples irradiated for 5 minutes. Each example underwent three repeated DSC measurements. The measured heat of polymerization (ΔH) was calculated by integrating the area under the curve from 0 to 200 s.

[0103] Here, t max It is the time to reach the maximum thermal evolution, t 95%This corresponds to the time point when 95% of the total heat of polymerization has been generated (0s corresponds to the photo-triggered moment). The double bond conversion (DBC) is based on the experimentally obtained heat of polymerization and the theoretical enthalpy of polymerization indicated in the literature (56 kJ / mol for methacrylate). -1 ) was calculated.

[0104] For (thermo)dynamic and water absorption tests, Example 1 or Reference Example 2 was mixed with two commercial oligomers, namely Ebecryl 8811 (Allnex), a difunctional aliphatic urethane acrylate, and BR-952 (Bomar), a difunctional aliphatic urethane methacrylate, in different proportions.

[0105] For sample preparation, a high-speed mixer (DAC 150.1 FVZ-K, Hauschild) was used. 70 g of the total formulation was mixed at 3000 rpm for 10 minutes. Afterward, the resin composition was degassed until no more bubbles were released.

[0106] The test specimens were printed on a Cubicure Caligma 200 DLP at 405 nm. The pulse duration was set to 6000, corresponding to a total exposure time of 1.5 s, and the printing speed was 20 mm / s. Due to the high volatility of Reference Example 2, the processing temperature was 35°C. The settings used resulted in a cure depth of 220 µm.

[0107] Using a DMA8000 dynamic thermodynamic analyzer from PerkinElmer, the dimensions of 50x5x1 mm were analyzed. 3 Dynamic thermodynamic analysis (DMA) was performed on the printed specimens. Measurements were conducted in tensile mode, ranging from 30–160 °C at a heating rate of 2 °C min⁻¹ and a frequency of 1 Hz. In these experiments, the evolution of the storage modulus G' with increasing temperature was observed, and T was determined. g (The maximum value of tanδ).

[0108] Water absorption was determined according to ISO 62. Each printed sample (10x10x1 mm) 3 The sample was pre-weighed and then placed in 25 mL of distilled water for 24 hours. Subsequently, the sample was cleaned and re-weighed, and the percentage of water absorption was calculated based on the increase in weight (4 replicates).

[0109] Example 1: Synthesis of 2-hydroxycyclohexyl methacrylate (HCMA)

[0110]

[0111] Methacrylic acid (308 g, 3.6 mol, 1 equivalent) and triethylbenzylammonium chloride (24.5 g, 0.11 mol, 0.03 equivalent) were mixed and stirred. The mixture was slowly heated to 70°C, and once the target temperature was reached, a mixture of hydroquinone (19.7 g, 0.18 mol, 0.05 equivalent) and cyclohexene oxide (352 g, 3.6 mol, 1 equivalent) was added dropwise over 3 hours. After the addition was complete, the temperature was raised to 90°C, and the reaction was stirred for 6 hours. Once the reaction was at room temperature, HCMA (2 mbar, boiling point (bp) = 115–121°C) was distilled, yielding a colorless, low-viscosity oil (476 g, 2.6 mol) in 72% yield. 1 H NMR (CDCl3): δ = 1.23 – 1.43 (m, 4H), 1.68 – 1.75 (m, 2H), 1.94 – 1.95(m, 3H), 2.01 – 2.08 (m, 2H), 3.58 – 3.65 (m, 1H), 4.60 – 4.68 (m, 1H), 5.56– 5.58 (m, 1H), 6.10 – 6.13 (m, 1H) ppm. 13 C NMR (CDCl3): δ = 18.5, 23.8, 24.0, 30.0, 33.1, 72.9, 78.5, 125.8, 136.6, 167.7 ppm.

[0112] Example 2: Synthesis of 2-(cyclohexylcarbonyloxy)cyclohexyl methacrylate

[0113]

[0114] HCMA (13.4 g, 72.9 mmol, 1 equivalent) was dissolved in 35 mL of DCM, and triethylamine (8.1 g, 80.2 mmol, 1.1 equivalent) and DMAP (0.18 g, 1.5 mmol, 0.02 equivalent) were added. The reaction mixture was placed under stirring and argon atmosphere and cooled to 0°C. Cyclohexane carbonyl chloride (11.4 g, 76.5 mmol, 1.05 equivalent) was added dropwise over 20 minutes. After the addition, the reaction mixture was kept at 0°C for 10 minutes, and then allowed to warm to room temperature. After 6 hours, the reaction mixture was filtered, and the solids were washed with DCM. The filtrate was washed with 2 M HCl, saturated sodium bicarbonate aqueous solution, and brine, and dried over sodium sulfate. After evaporation, the crude product was purified by column chromatography.

[0115] (PE:EtOAc 15:1) was used to obtain the desired product in 86% yield as a beige oil (18.5 g, 62.8 mmol). 1 H NMR (CDCl3): δ = 1.17 – 1.30 (m, 3H), 1.30 – 1.49 (m, 6H), 1.56 –1.63 (m, 1H), 1.65 – 1.75 (m, 4H), 1.75 – 1.85 (m, 2H), 1.88 – 1.92 (m, 3H),1.95 – 2.01 (m, 1H), 2.04 – 2.11 (m, 1H), 2.14 – 2.29 (m, 1H), 4.73 – 5.00(m, 2H), 5.44 – 5.64 (m, 1H), 5.97 – 6.14 (m, 1H) ppm. 13 C NMR (CDCl3): δ =18.4, 23.6, 23.6, 25.4, 25.6, 25.9, 28.9, 29.2, 30.2, 30.3, 43.4, 73.0, 74.2,125.8, 136.4, 166.8, 175.6 ppm.

[0116] Example 3: Synthesis of 2,2-dimethylpropionic acid 2-(isopropenylcarbonyloxy)cyclohexyl ester

[0117]

[0118] HCMA (3.0 g, 19.1 mmol, 1 equivalent) was dissolved in 20 mL of DCM, and triethylamine (3.1 g, 30 mmol, 1.7 equivalent) and DMAP (44 mg, 0.4 mmol, 0.02 equivalent) were added. The reaction mixture was placed under stirring and argon atmosphere and cooled to 0°C. Trimethylacetyl chloride (3.5 g, 28.0 mmol, 1.5 equivalent) was added dropwise over 20 minutes. After the addition, the reaction mixture was kept at 0°C for 10 minutes, and then allowed to warm to room temperature. After 8 hours, the reaction mixture was filtered, and the solids were washed with DCM. The filtrate was washed with 2 M HCl, saturated sodium bicarbonate aqueous solution, and brine, and dried over sodium sulfate. After evaporation, the crude substance was purified by column chromatography.

[0119] (PE:EtOAc 10:1) was used to obtain the desired product in 73% yield as a beige oil (3.6 g, 13.4 mmol). 1H NMR (CDCl3): δ = 1.12 (s, 9H), 1.31 – 1.54 (m, 4H), 1.66 – 1.80 (m,2H), 1.90 (s, 3H), 1.94 – 2.14 (m, 2H), 4.70 – 5.03 (m, 2H), 5.48 – 5.66 (m,1H), 5.97 – 6.17 (m,1H) ppm. 13 C NMR (CDCl3): δ = 18.4, 23.6, 23.6, 27.2, 30.2, 30.2, 38.8, 73.3, 74.1, 125.8, 136.4, 166.8, 178.0 ppm.

[0120] Example 4: Synthesis of 2-(benzylcarbonyloxy)cyclohexyl methacrylate

[0121]

[0122] HCMA (6.2 g, 34.0 mmol, 1 equivalent) was dissolved in 20 mL of DCM, and triethylamine (8.3 g, 81.6 mmol, 2.4 equivalent), DMAP (0.2 g, 1.7 mmol, 0.05 equivalent), and 3000 ppm phenothiazine were added. The reaction mixture was placed under stirring and argon atmosphere and cooled to 0°C, with phenylacetyl chloride (10.7 g, 68.0 mmol, 2 equivalent) added dropwise over 20 minutes. After the addition, the reaction mixture was kept at 0°C for 10 minutes, and then allowed to warm to room temperature. After stirring overnight, the reaction mixture was filtered, and the solid was washed with DCM. The filtrate was washed with 2 M HCl, saturated sodium bicarbonate aqueous solution, brine, and dried over sodium sulfate. After evaporation, the crude material was purified by column chromatography (dichloromethane) to obtain the desired product in 33% yield as a beige oil (3.4 g, 11.4 mmol). 1 H NMR (CDCl3): δ = 1.22 – 1.36 (m, 2H), 1.61 –1.67 (m, 2H), 1.72 – 1.75 (m, 3H), 1.88 – 2.05 (m, 2H), 3.48 (s, 2H), 5.36 –5.39 (m, 1H), 5.87 – 5.91 (m, 1H), 7.12 – 7.22 (m, 5H) ppm. 13C NMR (CDCl3): δ= 18.3, 23.5, 23.6, 30.2, 30.2, 41.8, 73.9, 74.2, 125.8, 127.1, 128.6, 129.2,134.1, 136.2, 166.7, 171.0 ppm.

[0123] Example 5: Synthesis of 2-(isopropenylcarbonyloxy)cyclohexyl 2-ethylhexanoate

[0124]

[0125] HCMA (4.4 g, 23.8 mmol, 1 equivalent) was dissolved in 6 mL of DCM, and triethylamine (4.1 g, 40.5 mmol, 1.7 equivalent) and DMAP (58 mg, 0.5 mmol, 0.02 equivalent) were added. The reaction mixture was placed under stirring and argon atmosphere and cooled to 0°C. 2-Ethylhexanoyl chloride (5.9 g, 35.7 mmol, 1.5 equivalent) was added dropwise over 20 minutes. After the addition, the reaction mixture was kept at 0°C for 10 minutes, and then allowed to warm to room temperature. After 8 hours, the reaction mixture was filtered, and the solids were washed with DCM. The filtrate was washed with 2 M HCl, saturated sodium bicarbonate aqueous solution, and brine, and dried over sodium sulfate. After evaporation, the crude substance was purified by column chromatography.

[0126] (PE:EtOAc gradient, 25:1 to 10:1), the desired product was obtained in 34% yield as a beige oil (2.5 g, 8.2 mmol). 1 H NMR (CDCl3): δ = 0.81 – 0.87 (m, 6H), 1.13 – 1.60 (m, 12H), 1.67 – 1.78 (m, 2H), 1.90 (s, 3H), 1.93 – 2.12 (m, 2H), 2.12 – 2.27 (m, 1H), 4.75 – 4.97 (m, 2H), 5.46 – 5.56 (m, 1H), 6.00 – 6.13 (m, 1H) ppm. 13 C NMR(CDCl3): δ = 12.0, 14.0, 18.4, 22.7, 23.6, 25.6, 25.7, 29.6, 29.7, 30.3,32.0, 47.8, 73.3, 74.0, 125.9, 136.4, 166.8, 175.9ppm.

[0127] Example 6: Determination of volatility, photoreactivity and viscosity

[0128] Volatility, viscosity, and photoreactivity are key parameters for evaluating the suitability of compounds as reactive diluents. Volatility is particularly important in high-temperature processes. Therefore, the above parameters were measured for Examples 1-5, as well as IBMA (Ref 1) and HEMA (Ref 2). The results are listed in Table 1.

[0129] Regarding viscosity, Examples 1-5 were observed to exhibit higher viscosities at room temperature than the two reference examples (Reference Example 1: 8 mPa·s; Reference Example 2: 6 mPa·s). Despite the higher viscosity at room temperature, Examples 1-3 already exhibited viscosities of approximately 50 mPa·s or lower (53, 27, and 13 mPa·s, respectively), making them suitable reactive diluents at that temperature. Examples 4 and 5 stood out due to their higher viscosities at room temperature (174 mPa·s and 110 mPa·s, respectively). However, the viscosity decreased sharply as the temperature increased. At 40°C, Example 5 had a viscosity of 53 mPa·s, making it suitable for use as a reactive diluent.

[0130] Volatility was measured at 50 and 80°C. The results clearly show that the synthesized polymerizable monomer exhibited significantly lower volatility than Reference Examples 1 and 2. At 50°C, Examples 1-5 showed a weight loss of 5% or less, while Reference Examples 1 and 2 showed weight losses of 12% and 34%, respectively. This difference was even more pronounced at 80°C, where Reference Example 1 showed a weight loss three times that of Example 1 (the most volatile monomer in Examples 1-5, with a weight loss of 20%). Reference Example 2 exhibited the highest volatility, with a weight loss more than four times that of Example 1.

[0131] ΔH and t were measured using optical-DSC experiments. max t 95% DBC was used to assess photoreactivity; heat of polymerization was detected in all examples except for example 5. Observing ΔH, Examples 1-4 showed values ​​similar to Reference Example 1 (~40 kJ / mol), but slightly lower than Reference Example 2 (52 kJ / mol). The calculated DBC of Examples 1-4 was between 80% and 85%, similar to Reference Example 1 (79%), but lower than Reference Example 2 (>99%). The reaction rates of Examples 1 and 2 were faster than those of Reference Examples 1 and 2 because they reached t max and t 95% The rate is faster. Regarding Example 3, a slower reaction was observed, while for Example 4, the rate of reaching maximum heat of polymerization was faster (lower t). max However, the reaction takes longer to complete (higher treaction).95% ).

[0132] In conclusion, following these preliminary studies, all the newly synthesized reactive diluents are promising alternatives to Reference Examples 1 and 2. Examples 1 and 2 appear most promising due to their low viscosity, high reactivity, and low volatility.

[0133] Table 1

[0134]

[0135] No heat of polymerization was detected in the photo-DSC experiment.

[0136] Monomers polymerize during volatility testing.

[0137] Example 7: (Thermo)mechanical testing and water absorption of cross-linked photopolymers

[0138] Considering the high reactivity, low viscosity, and low volatility of Example 1, this compound was selected as a reactive diluent for further testing and compared with Reference Example 2. The samples prepared for this purpose are shown in Table 2.

[0139] Table 2

[0140]

[0141] DMA and water absorption were measured for all samples, and the results are listed in Table 3.

[0142] DMA testing showed that the photopolymer containing Example 1 exhibited a higher T than the corresponding control group containing Reference Example 2. g and G' 30°C For example, Example 8 exhibited a T value of 141°C. g and 3327 MPa G' 30°C T is higher than the 136°C observed in Reference Example 3. g and 2662 MPa of G' 30°C It is also noted that increasing the percentage of Reference Example 2 on T g The negative impact was more significant than in Example 1 because when the percentage in Reference Example 2 was increased from 10% to 30% (Reference Example 3 compared to Reference Example 4), the T of the photopolymer... gThe water absorption rate decreased by 13%, while the same change in the content of Example 1 (Example 8 compared to Example 9) resulted in only a 4% decrease. Water absorption tests clearly showed that using Example 1 as the reactive diluent resulted in a significantly lower water absorption rate for the final polymer compared to Reference Example 2. When oligomer X-851-1066 was mixed with 10% reactive diluent (Example 8 and Reference Example 3), only a small difference of 0.1% in water absorption rate was observed. However, when the proportion of reactive diluent was increased to 30%, the water absorption rate of the sample containing Example 1 (Example 9) remained unchanged at 0.8%, while the water absorption rate of the sample containing Reference Example 2 (Reference Example 4) increased almost threefold (from 0.9% to 2.6%). Examples 10 and 5 (photopolymers of Ebecryl 8811 and X-851-1066 with one of the reactive diluents) exhibited higher water absorption rates than the others, likely due to the higher water absorption rate of resin Ebecryl 8811. However, the previously described trend was still observed, as the water absorption rate of the sample containing Reference Example 2 was more than twice that of the sample containing Example 1 (5.6% vs. 2.1%).

[0143] Table 3

[0144]

[0145] In summary, the results clearly demonstrate that the disclosed compound exhibits a viscosity in the range of 1-100 mPa·s at process temperatures ranging from 40 to 90 °C, and possesses significantly lower volatility compared to prior art reactive diluents (less than 5% volatility at 50 °C and less than 20% at 80 °C after 24 hours for the tested diluents), thus making it highly suitable as a reactive diluent. Furthermore, the tested reactive diluents exhibited high reactivity, resulting in faster gelation compared to prior art diluents (i.e., faster tg in photo-DSC experiments). max As can be seen, especially for Examples 1, 2, and 4). Rapid gelation is an important feature of resin compositions used for 3D printing in order to keep processing time to a minimum and produce 3D structures with high green strength.

[0146] A comparative study of Example 1 and Reference Example 2 showed that the photopolymer containing Example 1 exhibited a higher T than the corresponding control group containing Reference Example 2. g and G' 30°CThese improved properties can be attributed to the rigid alicyclic moiety represented by the diluent according to Formula I, and the alicyclic nature and asymmetric substitution mode resulting from the compounds according to Formula I also ensure a low tendency for crystallization, thus making these compounds according to the invention particularly suitable as reactive diluents for high-temperature (e.g., 30-150 °C) 3D printing resin compositions. The improved (thermo)mechanical properties are beneficial to the 3D printing process itself, but are also particularly important for the final application of the 3D printed structure.

[0147] Furthermore, the water absorption test clearly demonstrates that using Example 1 as the reactive diluent results in a significantly lower water absorption rate in the final polymer compared to using the compound of Reference Example 2. This can be explained by the larger alicyclic moiety imparting greater hydrophobicity to the reactive diluent of Example 1, and thus also to the other examples according to Formula I. The benefits described make the reactive diluents of the disclosed class particularly promising as reactive diluents in resin compositions for 3D printing.

Claims

1. A resin composition for 3D printing, the resin composition comprising: a) at least one curable oligomer or prepolymer resin component (compound B), and b) A reactive diluent (compound A) having one or more chemical substances that are alicyclic compounds according to formula (I): (Formula I) in: n is an integer between 1 and 5; R 1 It is hydrogen or methyl; X is either -O- or -NR2-; R 2 It is H or alkyl; R 3 R 4 R 5 and R 6 Independently, it is H, a straight-chain or branched C1-C20 aliphatic group or a C5-C8 alicyclic group; or R 3 and R 4 All are carbonyl groups and / or R 5 and R 6 All are carbonyl groups; Y is carbon, oxygen, sulfur, sulfone, or it may not exist. Z is a carbonyl group, or it can form a carbonate (-CO-O-) or carbamate group (-CO-NR). 8 (or does not exist); R 7 R 8 Independently, it can be H, a straight-chain or branched C1-C20 aliphatic group, a C5-C8 alicyclic group, a heterocyclic group, such as tetrahydrothiophene, or a substituted or unsubstituted aromatic group, wherein the substituent of the aromatic group can be H, a straight-chain or branched C1-C10 aliphatic group, a methoxy or ethoxy group, or a halogen, such as F, Cl, Br or I.

2. The resin composition according to claim 1, characterized in that, In equation (I), n is 1 or 2.

3. The resin composition according to claim 1, characterized in that, In equation (I), when Y does not exist, n is 2 or 3.

4. The resin composition according to claim 1, 2 or 3, characterized in that, The at least one curable oligomer or prepolymer resin component is selected from (meth)acrylates, (meth)acrylamide, vinyl esters, vinyl ethers, vinyl amides, vinyl carbonates, styrene, itaconic acid esters, fumarates, maleimides and their derivatives.

5. The resin composition according to any one of claims 1 to 4, characterized in that, The at least one curable oligomer or prepolymer resin component includes one or more monofunctional or polyfunctional chemical substances.

6. The resin composition according to any one of claims 1 to 5, characterized in that, As determined by GPC or SEC, the molecular weight of the at least one curable oligomer or prepolymer resin component is greater than 450 g / mol, preferably greater than 1000 g / mol.

7. The resin composition according to any one of claims 1 to 6, characterized in that, Based on the total weight of at least one curable oligomer or prepolymer resin component and a reactive diluent, the amount of the reactive diluent is from 5 wt% to 80 wt%, preferably from 5 wt% to 60 wt%, more preferably from 5% to 50%, and even more preferably from 5 wt% to 40 wt%.

8. The resin composition according to any one of claims 1 to 7, characterized in that, Based on the total weight of at least one curable oligomer or prepolymer resin component and reactive diluent, the amount of the at least one curable oligomer or prepolymer resin component is 20 wt% to 95 wt%, preferably 40 wt% to 95 wt%, more preferably 50 wt% to 95 wt%, and even more preferably 60 wt% to 95 wt%.

9. The resin composition according to any one of claims 1 to 8, characterized in that, The weight loss of the reactive diluent after being placed at temperatures up to 50°C for 24 hours is less than 10%, preferably less than 5%, and more preferably less than 1%.

10. The resin composition according to any one of claims 1 to 9, characterized in that, The reactive diluent has a viscosity of 1 to 60 mPa·s, preferably 1 to 40 mPa·s, and more preferably 1 to 20 mPa·s at a processing temperature between 30 and 150°C.

11. The resin composition according to any one of claims 1 to 10, characterized in that, In equation (I), R 7 Select from the following structures, where the dashed lines indicate the positions of the bonds connected to Z in equation (I): 。 12. The resin composition according to any one of claims 1 to 11, characterized in that, The reactive diluent according to general formula (I) is selected from the following compounds: 2-Hydroxycyclohexyl methacrylate (Ex 1) 2-(cyclohexylcarbonyloxy)cyclohexyl methacrylate (Ex 2) 2,2-Dimethylpropionic acid 2-(isopropenylcarbonyloxy)cyclohexyl ester (Ex 3) 2-(benzylcarbonyloxy)cyclohexyl methacrylate (Ex 4) 2-Ethylhexanoic acid 2-(isopropenylcarbonyloxy)cyclohexyl ester (Ex 5) 。 13. The resin composition according to any one of claims 1 to 12, characterized in that, It also contains at least one polymerizable photoinitiator, which is preferably 0.01 wt% to 10 wt%, more preferably 0.1 wt% to 7 wt%, and more preferably 0.2 wt% to 5 wt%, based on the total weight of at least one curable oligomer or prepolymer resin component and reactive diluent in the composition.

14. The resin composition according to any one of claims 1 to 13, characterized in that, It also contains a polymerization thermal initiator and / or a thermosetting catalyst.

15. The resin composition according to any one of claims 1 to 14, characterized in that, It also contains a second polymerizable system, suitable as a dual-curing system.

16. The resin composition according to any one of claims 1 to 15, characterized in that, It also contains one or more components selected from polymerization initiators, polymerization inhibitors, solvents, fillers, antioxidants, pigments, dyes, surface modifiers and flame retardants.

17. A method of manufacturing an object by 3D printing, wherein the resin composition according to any one of claims 1 to 16 undergoes the following steps: a) A light-induced structuring step, optionally pre-cured via a second exposure, and b) The subsequent heat-induced curing step.

18. The method according to claim 17, characterized in that, The photo-induced structuring step is carried out at a processing temperature of 30°C to 150°C, more preferably 35°C to 100°C, and even more preferably 40°C to 90°C for the resin composition.

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